Portable communication terminal and error correction method of terrestrial magnetism sensor thereof

The present invention relates to a mobile communication terminal such as a mobile phone provided with a geomagnetic sensor for measuring a geographical orientation, and an error correction method for the geomagnetic sensor.

Conventionally, there has been a demand for a device that confirms the geographical position of the current location and guides the way to the destination by a map, and a car navigation device is known as satisfying such a request.

In general, a car navigation device determines the geographical position of the current location by receiving and processing signals (hereinafter referred to as GPS signals) transmitted from a plurality of GPS (global positioning system) satellites, and determines the geographical position of the current location, and around the current location. The map data is read from the database stored in the storage unit (DVD, hard disk, etc.) in the device and displayed on the display. In addition, the vehicle speed sensor and the gyro sensor are used to calculate the movement locus of the vehicle, and map matching processing is performed to detect the degree of coincidence between the vehicle and the road on the map to correct the positioning error.

However, there is a desire to know one's position and the way to the destination even when not in a car, and as a way to meet these demands, mobile phones equipped with a simple navigation function have appeared. are doing.

Initially, mobile phones with navigation functions did not have a device for measuring orientation, so the heading-up display (map so that the direction of travel is toward the top of the screen), which is commonly used in car navigation devices, is displayed. It was difficult to display a map that was easy for the user to understand, such as a rotating display.

Therefore, in recent years, a mobile phone with a navigation function has been proposed, which measures the direction using a geomagnetic sensor and enables heading-up display.<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2004-28837</text></patcit><patcit num="2"><text>Japanese Patent Application Laid-Open No. 2002-328042</text></patcit><patcit num="3"><text>Japanese Unexamined Patent Publication No. 10-197258</text></patcit>

<p> By the way, the reinforcing bars of buildings and the drive trains of trains generate a strong magnetic field that causes a detection error of the geomagnetic sensor. Therefore, when pedestrians use the navigation function of mobile phones in the city, they are often affected by such an external magnetic field. The accuracy of the orientation may decrease.</p><p> On the other hand, the detected value of the geomagnetic sensor includes an error (offset error) of a static magnetic field generated by a component in the mobile phone. Since this offset error changes even when the mobile phone is placed on a magnetic object, for example, it is necessary to periodically correct it while using the navigation function.</p><p> However, if this offset error correction processing is performed in an environment that receives a strong external magnetic field, erroneous correction is performed, causing a steady error in the geomagnetic field detection value, and the accuracy of the orientation is lowered. Since such a state of reduced directional accuracy continues until the next offset error is corrected, inaccurate directional information will continue to be displayed for a long period of time.</p><p> The present invention has been made in view of such circumstances, and an object of the present invention is an error correction method for a mobile communication terminal and its geomagnetic sensor that can prevent orientation correction from being performed in an environment in which a geomagnetic detection error due to an external magnetic field is likely to occur. Is to provide.</p>

<p> In the first aspect of the present invention, a geomagnetic direction is calculated based on a geomagnetic sensor for detecting the geomagnetism, a display means, and a value detected by the geomagnetic sensor, and the calculated direction information is displayed on the display means. A mobile communication terminal having a control means, wherein the control means waits after the detection value of the geomagnetic sensor becomes a predetermined abnormal state when the display means displays the information of the direction. When the predetermined abnormal state continues for a predetermined time, the information of the above-mentioned orientation is corrected.</p><p> The geomagnetic sensor may detect the geomagnetism in a plurality of directions orthogonal to each other, and the control means may detect the geomagnetism in the plurality of directions after at least one of the detected values of the geomagnetism in the plurality of directions becomes a predetermined abnormal state. When the abnormal state continues for a predetermined time, the information of the direction may be corrected by performing a process of detecting and correcting the offset error of the geomagnetic sensor.</p><p> The control means takes the predetermined time from when at least one of the detected values of the geomagnetism in the plurality of directions becomes a predetermined abnormal state until all the detected values of the geomagnetism in the plurality of directions are not in the abnormal state. If not, the offset error detection and correction processing may not be performed.</p><p> The predetermined abnormal state may be a state in which the detected value of the geomagnetic sensor deviates from the predetermined normal range.</p><p> The geomagnetic sensor may convert an analog signal of the geomagnetism into a digital signal of a predetermined digit and output it as a detection value of the geomagnetism. In the predetermined abnormal state, the detection value of the geomagnetism sensor is the maximum value of the predetermined digit. Alternatively, it may be in a state equal to the minimum value.</p><p> The control means provides information indicating that the accuracy of the directional information is low and / or that the correction process of the directional information is being executed when the correction process of the directional information is being executed. It may be displayed by the above display means.</p><p> The control means displays information indicating that the accuracy of the directional information has been restored and / or the correction process of the directional information has been completed when the correction process of the directional information is completed. It may be displayed in.</p><p> The first invention may have a position information acquisition means for acquiring information related to the geographical position of the current location, and the control means is specified based on the position information acquired by the position information acquisition means. The map around the current location is displayed on the display means, and the orientation of the map on the display screen of the display means is controlled according to the calculated orientation. During the process, the geomagnetic sensor When the predetermined abnormal state continues for a predetermined time after the detected value becomes a predetermined abnormal state, the control of the orientation of the map is stopped, and the predetermined direction on the map is set to the predetermined direction on the display screen. It may be fixed in the direction.</p><p> After stopping the control of the orientation of the map, the control means may resume the control of the orientation of the map when the correction process of the orientation information is completed.</p><p> A second invention of the present invention is a mobile communication terminal having a geomagnetic sensor for detecting the geomagnetism and a display means for displaying geographic orientation information calculated based on the detection value of the geomagnetic sensor. It is an error correction method of the geomagnetic sensor that corrects the error of the above, and when the information of the orientation is displayed on the display means, the detection value of the geomagnetic sensor becomes a predetermined abnormal state, and then the predetermined state is obtained. When it is detected in the first step of monitoring whether or not the abnormal state has continued for a predetermined time and the abnormal state of the detection value of the geomagnetic sensor has continued for a predetermined time in the first step, the information of the orientation is corrected. It has a second step to be performed.</p>

<p> According to the present invention, it is possible to prevent the orientation from being corrected in an environment where a geomagnetic detection error due to an external magnetic field is likely to occur.</p>

Hereinafter, an embodiment in the case where the present invention is applied to a multifunctional mobile phone having a navigation function and an imaging function will be described with reference to the drawings.

FIG. 1 is a block diagram showing a configuration example of a system for acquiring information on a geographical position and a map in the mobile phone 100 according to the embodiment of the present invention.

The mobile phone 100 receives GPS signals transmitted from three or more GPS satellites 200 orbiting a known orbit. Then, the information regarding the received GPS signal is transmitted from the base station 300 to the GPS server device 401 via the communication network, and the position information of the current location is acquired from the GPS server device 401. Further, the mobile phone 100 transmits the position information of the current location acquired from the GPS server device 401 from the base station 300 to the navigation server device 402 via the communication network, and the map information around the current location is transmitted from the navigation server device 402. get.

The GPS server device 401 calculates the geographical position (for example, latitude and longitude) of the mobile phone 100 based on the information of the GPS signal sent from the mobile phone 100 via the communication network. Then, the calculated position information is transmitted from the communication network to the mobile phone 100 via the base station 300.

The navigation server device 402 searches the database for map information around the mobile phone 100 based on the location information sent from the mobile phone 100 via the communication network. Then, the searched map information is transmitted from the communication network to the mobile phone 100 via the base station 300.

2, FIG. 3, and FIG. 4 are views showing an example of the appearance of the mobile phone 100. FIG. 2 is a perspective view of the mobile phone 100 in the open state, FIG. 3 is a perspective view from one side of the mobile phone 100 in the closed state, and FIG. 4 is a mobile phone in the closed state. It is a perspective view from the other side of the telephone 100.

As shown in the figure, in the mobile phone 100, the first housing (upper housing) 2 and the second housing (lower housing) 3 can be opened and closed (rotatably) via the movable mechanism portion 4. It is connected. The movable mechanism unit 4 is configured so that the two housings, the first housing 2 and the second housing 3, can be relatively rotated around a predetermined rotation axis.

As shown in FIGS. 2 and 3, the first housing 2 has, for example, an LCD (liquid crystal display) panel or an LCD (liquid crystal display) panel on the first surface 2a that is exposed regardless of the operating state (open state, closed state) of the movable mechanism unit 4. A display panel 21 composed of an organic EL (electroluminescent) display panel is arranged. A speaker 22 is built in the upper part of the display panel 21 in FIG. The display panel 21 is included in the display unit 155 described later. The speaker 22 is included in the voice processing unit 156, which will be described later.

The second housing 3 is configured by superimposing a board-mounted housing 31 on which a board is mounted inside and a lid-side housing 32 forming a lid of the board-mounted housing 31.

On the outer flat surface 31a of the board-mounted housing 31 of the second housing 3, that is, the surface 31a facing one side of the first housing 2 in the closed state, a numeric keypad button 311a, a cursor button 311b, and a decision button 311c are provided. The operation key 311 to be held is arranged. The microphone 312 is built in the lower part of FIG. 2 of the operation key 311. The operation key 311 is included in the key input unit 154 described later. The microphone 312 is included in the voice processing unit 156, which will be described later.

As shown in FIG. 4, the outer plane 32b exposed in the lid-side housing 32 of the second housing 3 regardless of whether it is in the open state or the closed state is closer to the connecting portion of the movable mechanism portion 4 than the central portion thereof. , The optical system 34a of the camera module 34 is arranged. Further, in the outer flat surface 32a of the lid side housing 32 of the second housing 3, a flash of light from the built-in flash lamp is radiated to the outside in parallel with the optical system 34a on the side closer to the connecting portion than the optical system 34a. A light emitting window 321 for this purpose and a light emitting window 322 for emitting white light as a shooting aid at the time of close-up photography or the like are arranged. The camera module 34 is included in the imaging unit 157, which will be described later.

As shown in FIGS. 2 and 3, a camera module tact switch 35 is arranged on one side of the second housing 3, and on the other side of the second housing 3, the connecting portion is used. A memory card slot 33 for inserting a memory card is formed on the near side.

FIG. 5 is a perspective view showing a board mounting state inside 31b of the board mounting housing 31. As shown in FIG. 5, the main board 37 is mounted on the inside 31b of the board mounting housing 31 over the entire bottom surface portion thereof. A memory card unit 159 on which a removable memory card is mounted is mounted on the main board 37 at a position facing the memory card slot 33. Further, the geomagnetic sensor 158 is mounted at a position near the center of the main board 37 adjacent to the memory card unit 159.

FIG. 6 is a block diagram showing a configuration example of the mobile phone 100 according to the embodiment of the present invention. The mobile phone 100 illustrated in FIG. 6 includes a wireless communication unit 150, a GPS signal reception unit 151, a storage unit 152, an open / close determination unit 153, a key input unit 154, a display unit 155, and an audio input / output unit 156. It has an imaging unit 157, a geomagnetic sensor 158, a memory card unit 159, and a control unit 160. The wireless communication unit 150 is an embodiment of the wireless communication means of the present invention. The GPS signal receiving unit 151 is an embodiment of the GPS signal receiving means of the present invention. The GPS signal receiving unit 151 and the wireless communication unit 150 are an embodiment of the position information acquisition means of the present invention. The open / close determination unit 153 is an embodiment of the operating state determination means of the present invention. The display unit 155 is an embodiment of the display means of the present invention. The geomagnetic sensor 158 is an embodiment of the geomagnetic sensor of the present invention. The memory card unit 159 is an embodiment of the storage medium mounting means of the present invention. The control unit 160 is an embodiment of the control means of the present invention.

The wireless communication unit 150 performs processing related to wireless communication with the base station 300. For example, the transmission data output from the control unit 160 is subjected to a predetermined modulation process, converted into a radio signal, and transmitted from the antenna. Further, the radio signal received by the antenna is subjected to a predetermined demodulation process to reproduce the received data and output it to the control unit 160. In addition, the wireless communication unit 150 also performs a process of receiving a reference signal for positioning sent from the base station 300 as a position information acquisition means.

The GPS signal receiving unit 151 receives the GPS signal transmitted from the GPS satellite 20 and performs signal processing such as amplification, noise removal, and modulation to calculate the geographical position of the mobile phone 100 in the GPS server device 401. Get the information you need.

The storage unit 152 stores a program executed by the control unit 160, constant data used in the processing of the control unit 160, variable data that needs to be temporarily stored, captured image data, and the like.

The open / close determination unit 153 determines whether the state of rotation of the first housing 2 and the second housing 3 by the movable mechanism unit 4 is the above-mentioned open state or closed state. For example, the open / close determination unit 153 includes a detector such as a switch that detects a closed state in which the first housing 2 and the second housing 3 overlap each other, and determines the closed state and other states. Determine.

When an input operation such as pressing a key is performed on the operation key 311 or the tact switch 35 for the camera module described above, the key input unit 154 generates a signal corresponding to the input operation and outputs the signal to the control unit 160. ..

The display unit 155 causes the display panel 21 to display an image corresponding to the image data generated by the control unit 160.

The voice processing unit 156 converts the input voice into an electrical voice signal in the microphone 312, performs signal processing such as amplification, analog-to-digital conversion, and coding, and sends the voice data of the processing result to the control unit 160. Output. Further, the audio data input from the control unit 160 is subjected to signal processing such as decoding, digital-analog conversion, and amplification to generate an audio signal, which is converted into audio by the speaker 22.

The imaging unit 157 captures an image incident on the optical system 34a described above, generates image data of a still image or a moving image, and outputs the image data to the control unit 160. Further, according to the control of the control unit 160, the flash lamp is turned on at the time of imaging and emitted from the light emitting window 321.

The geomagnetic sensor 158 detects the geomagnetism used to calculate the orientation. For example, as shown in FIG. 5, the geomagnetic sensor 158 detects geomagnetism in three directions orthogonal to each other at a fixed position on the main substrate 37. That is, the geomagnetism in each axial direction is detected with reference to the coordinate system of predetermined three axes set on the main board 37. For the detection of the geomagnetism, various methods such as a method using the excitation of the coil, a method using the Hall effect, and a method using a magnetoresistive element are used.

In the present embodiment, as an example, the geomagnetic sensor 158 is equipped with an analog-digital converter, and the geomagnetic analog signal obtained by the above method is converted into an 8-bit digital signal and output. .. That is, it is assumed that the detected values of the geomagnetism in the three directions are output as integer values from '0' to '255', respectively.

The control unit 160 has a computer that executes processing based on a program stored in the storage unit 152, and performs various processing related to the overall operation of the mobile phone 100. For example, as processing related to the function of the telephone, processing for controlling the sequence of calling and receiving calls of the wireless communication unit 150 in response to the key input operation in the key input unit 154, and voice data input / output in the voice processing unit 156. Is transmitted and received by the wireless communication unit 150. As a process related to the data communication function, a process of operating the wireless communication unit 150 in response to a key input operation in the key input unit 154 to communicate with a predetermined mail server device and exchanging data such as e-mail is performed. Do. The processing related to the image pickup function includes a process of causing the image pickup unit 157 to perform an image pickup process of a still image or a moving image in response to a key input operation in the key input unit 154, and an image such as compression coding of the image data of the captured image. Processing is performed and stored in the storage unit 152. When shooting a still image, the flash lamp is turned on at an appropriate timing.

The control unit 160, navigate as processing associated with Shon function, processing for calculating a geographical bearing based on the detection values of the geomagnetic sensor 158, GPS server information of the GPS signals received by the GPS signal reception unit 151 Processing to send to 401 to acquire the position information of the current location, processing to send this position information to the navigation server device 402 to acquire map information around the current location, calculation result of positioning signal and orientation from base station 300 A process of determining the current location based on the above, a process of controlling the orientation of the map on the display screen of the display unit 155 according to the calculation result of the orientation (heading-up display process), and the like are performed.

Further, the control unit 160 rotates the display image of the display unit 155 according to the determination result of the open / close determination unit 153 in order to deal with the fact that the orientation of the display panel 21 with respect to the user differs by 180 degrees between the open state and the closed state. Perform the process of applying.

Here, the operation of the mobile phone 100 having the above-described configuration will be described focusing on the navigation function related to the present invention.

First, the GPS signal reception process will be described.

FIG. 7 is a flowchart illustrating an example of GPS signal reception processing in the mobile phone 100.

The control unit 160 controls the GPS signal reception unit 151 at a fixed timing such as an interval of 2 seconds to scan the GPS signal from the satellite (steps ST102 and ST104). If a GPS signal can be received as a result of scanning, that information is stored in the storage unit 152 (ST106). Such scanning of GPS signals and storage of information are repeated for all receivable satellites (steps ST108, ST104, ST106). After scanning all satellites, wait until the next GPS signal reception timing, and perform the processing of steps ST104 to 108 again. The control unit 160 always executes such GPS signal reception processing during a period when the power is on, for example.

Next, the navigation process will be described.

FIG. 8 is a flowchart illustrating an example of navigation processing in the mobile phone 100.

When the start of the navigation process is selected by, for example, a key input operation in the key input unit 154 (step ST122), the control unit 100 first transfers the information obtained by the GPS reception process described above from the wireless communication unit 150 to the base station. 300, the process of transmitting to the GPS server device 401 via the communication network is performed (step ST124). When the GPS server device 401 receives GPS information from the mobile phone 100, the GPS server device 401 calculates the current position (for example, latitude and longitude information) of the mobile phone 100 based on the received GPS information, and calculates the calculation result on the communication network. Is transmitted to the mobile phone 100 via the base station 300. The mobile phone 100 receives the position information transmitted from the GPS server device 401 and stores it in the storage unit 152 (step ST126).

Next, the control unit 100 accesses the navigation server device 402 from the wireless communication unit 150 via the base station 300 and the communication network (step ST128), and transmits the acquired position information to the navigation server device 402 (step ST130). .. When the navigation server device 402 receives the location information from the mobile phone 100, the navigation server device 402 searches the database for map information around the current location of the mobile phone 100 identified by the location information, and searches the searched map information from the communication network for the base station. Send to mobile phone 100 via 300. The mobile phone 100 receives the map information transmitted from the navigation server device 402 and stores it in the storage unit 152 (step ST132).

FIG. 9 is a diagram showing an example of map information transmitted from the navigation server device 402. In the present embodiment, as an example, it is assumed that a unique identification number is assigned to each map information. The navigation server device 402 manages map data for each predetermined size (for example, 1 km square) based on this identification number, and when transmitting map information to the mobile phone 100, this identification number is used for the map. Attach it to the data and send it. In the example of FIG. 9, the map around the current location has the identification number MP0, and the maps on all four sides have the identification numbers MP1 to MP4.

When such map information is acquired, the control unit 160 generates image data of a map around the current location based on the acquired map information, and displays the map on the display panel 21 of the display unit 155 (step ST134).

As shown in FIG. 9, for example, the map area displayed on the display panel 21 is a narrower area (for example, 200 m × 300 m) than the 1 km square map acquired from the navigation server device 402.

As the map display method, for example, one of north-up display (display in which the north on the map faces the top of the screen) and heading-up display (display in which the direction of travel on the map faces the top of the screen) can be selected. Is. When the north-up display is selected by the key operation of the key input unit 154, the control unit 160 fixes the north direction of the map to the upper direction of the display screen and displays it on the display unit 155.

On the other hand, when the heading-up display is selected by the key operation of the key input unit 154, the control unit 160 performs a process of controlling the direction of the map on the display screen according to the direction obtained by the direction calculation process described later. .. For example, when the direction A (see FIG. 2) from one end where the microphone 312 of the second housing 3 is arranged toward the other end having the connecting portion is set as the traveling direction, the direction of this traveling direction is displayed. Control the orientation of the map on the display screen so that it faces the top of the screen.

The "above the display screen" described here is a view from the viewpoint of a user who holds the second housing 3 and uses the mobile phone 100, and indicates the open / closed state of the housing. When it is changed, the "above the display screen" also changes accordingly. That is, when the housing is in the open state, the speaker 22 side in the first housing 2 is above the display screen, and when the housing is in the open state, the connecting portion side in the first housing 2 is above the display screen. .. As will be described later, the control unit 160 performs a process of rotating the image on the display screen according to the open / closed state of the housing, and causes the user to display the image in an appropriate direction.

When the map display is started as described above, the control unit 160 repeats the following steps ST138 and subsequent steps until the end of the navigation process is selected by the key operation of the key input unit 154 (step ST136). ).

First, the control unit 160 causes the wireless communication unit 150 to receive a reference signal for positioning transmitted from a plurality of (for example, three or more) base stations 300 around the mobile phone 100, and the position of the current location based on the received signal. Is calculated (step ST138). Then, it is determined from the calculation result of the current location whether or not the mobile phone 100 is moving (step ST140), and if it is determined that the mobile phone 100 is not moving, the calculation of the current location based on the reference signal from the base station 300 is continued. Do (ST138).

When it is determined in step ST140 that the mobile phone 100 has moved, the control unit 160 determines whether or not the destination point is in the area at the end of the map currently acquired (step ST142). For example, if a part of the map to be displayed on the display unit 155 is not included in the currently acquired map but is included in the map adjacent to the map, the current location is in the area at the edge of the map. judge. If it is determined that the current location is in the edge region, the control unit 160 requests the navigation server device 146 for a map adjacent to this edge region (step ST146). For example, the identification number of the map currently being acquired and the information indicating which direction of north, south, east, and west are adjacent to this map are transmitted to the navigation server device 146. The navigation server device 146 detects a map corresponding to the information sent from the mobile phone 100 from the database and transmits the map to the mobile phone 100. The mobile phone 100 receives the map information transmitted from the navigation server device 402 and stores it in the storage unit 152 (step ST132), and displays the map corresponding to the map information on the display unit 155 (step ST134). After that, the processes after step ST138 are repeated. If it is determined that the current location is not in the edge region, the control unit 160 performs a process of moving the map display area so that, for example, the current location of the mobile phone 100 is in the center of the map according to the calculation result of the current location. After that, the processing after step ST138 is repeated.

Next, the rotation processing of the display image according to the open / closed state of the housing will be described.

FIG. 10 is a flowchart illustrating an example of rotation processing of the display image in the mobile phone 100.

The control unit 160 constantly monitors the open / closed state determined by the open / close determination unit 153 while the power is on (step ST162). Then, when the open / close determination unit 153 determines that the open state is not closed (that is, the open state), the image is displayed on the display panel 21 with the speaker 22 side of the first housing 2 facing upward from the image (step ST166). ). Assuming that the display in the open state is the normal display, when the open / close determination unit 153 determines the closed state, the control unit 160 rotates the image in the normal display by 180 degrees and displays it on the display panel 21 (step ST164). That is, the image is displayed on the display panel 21 with the connecting portion side of the first housing 2 facing upward from the image. By such rotation processing of the display image, the image can be displayed on the display unit 155 in a direction that is easy for the user to see regardless of whether the housing is open or closed.

Next, the direction calculation process will be described. Here, first, the outline of the direction calculation method will be described with reference to FIG. 11, and then some examples of the direction calculation process in the control unit 160 will be described with reference to FIGS. 12 to 19.

FIG. 11 is a diagram for explaining a method of calculating the azimuth angle. In FIG. 11, the Cartesian coordinate system having the coordinate axes Hx, Hy, and Hz is a reference coordinate system set on the ground plane. That is, the coordinate axes Hx and Hy are coordinate axes parallel to the ground plane, and each faces a predetermined direction. The coordinate axis Hz is a coordinate axis that points in a direction perpendicular to the ground plane. The azimuth angle θ is the angle formed by the image Zxy and the coordinate axis Hx, which is an orthographic projection of the vector of the reference direction (for example, the direction A in FIG. 2) of the geomagnetic detection set on the main substrate 37 of the second housing 3 on the ground plane. Is. The tilt angle φ is the angle formed by this image Zxy and the vector in the reference direction A. The twist angle η is an angle obtained by rotating the mobile phone 100 around the vector of the reference direction A as a rotation axis. When the azimuth angle θ, the inclination angle φ, and the twist angle η are all zero, the coordinate system for geomagnetic detection set on the main board 37 of the second housing 3 has the coordinate axes Hx, Hy, and Hz shown in FIG. Matches the coordinate system.

Here, assuming that the detected value of the geomagnetism corresponding to the coordinate axis Hx is α, the detected value of the geomagnetism corresponding to the coordinate axis Hy is β, and the detected value of the geomagnetism corresponding to the coordinate axis Hz is γ, the tangent of the azimuth angle θ shown in FIG. tan θ is expressed by the following equation.

(Equation 1) tan θ = β / (γ sinφ-α cosφ) ... (1)

However, in Eq. (1), the twist angle η is set to zero. The control unit 160 calculates the azimuth angle according to the detected value of the geomagnetism in the three directions obtained from the geomagnetic sensor 158 by using the relationship shown in the equation (1), for example.

The control unit 160 also takes into account the inclination angle of the display panel 21 with respect to the ground plane in calculating the above-mentioned direction. A general user can view the image of the display panel 21 in a comfortable posture when the display panel 21 is tilted at an angle of, for example, about 45 degrees. Therefore, the control unit 160 calculates the azimuth by the equation (1) using the inclination angle φ when the inclination angle of the display panel 21 with respect to the ground plane is, for example, 45 degrees.

When the tilt angle of the geomagnetic sensor 158 with respect to the ground plane is different between the open state and the closed state, the control unit 160 may calculate the azimuth angle of each state in consideration of the difference in the tilt angle. For example, in the closed state, the first housing 2 and the second housing 3 overlap almost in parallel, while in the open state, the first housing 2 and the second housing 3 are relatively inclined (for example, "" It is assumed that the two housings are connected so as to be tilted in a dogleg shape). In this case, when the user tries to keep the direction of the line of sight with respect to the display panel 21 constant in both operation styles, the inclination of the second housing 3 with respect to the ground plane differs between the open state and the closed state. The difference in the inclination of the second housing 3 means that the inclination of the reference direction A with respect to the ground plane is different in the open and closed states. Therefore, the control unit 160 calculates the direction using the inclination angle φ of a predetermined angle according to the determination result of the open / close determination unit 153. The inclination angle φ is a preset angle so that the inclination angle of the display panel 21 with respect to the ground plane is constant at, for example, 45 degrees in both the open state and the closed state.

The tilt angle information is stored in advance in the storage unit 152 as, for example, a data table. When the orientation is detected, the control unit 160 reads the tilt angle information associated with the determination result of the open / close determination unit 153 from this data table, and calculates the orientation using the tilt angle information.

FIG. 12 is a flowchart illustrating the first example of the orientation calculation process in the mobile phone 100.

When the start of the navigation process is selected by a key input operation or the like in the key input unit 154 (step ST202), the control unit 160 checks whether or not a predetermined event has occurred (step ST204).

Here, the predetermined event is the geomagnetic sensor 158 in the circuit or processing system in the mobile phone 100 when the direction information (such as a map of the heading-up display or a compass showing the direction) is displayed on the display unit 155. This is an event that generates a magnetic field that causes a change in the detected value of. This predetermined event includes, for example, an event for operating the wireless communication unit 150 when acquiring a map from the navigation server device 402 in step ST146 of FIG. 8, or when performing incoming call processing or mail reception processing. In addition, an event that changes the display brightness on the display unit 155 in response to a key input operation, a change in directional information, an update of the map display, etc., an event that operates the voice processing unit 156 to output sound from the speaker, and the like are generated. It may be included. When the display unit 155 has an LCD panel, it may include, for example, an event for turning on / off a light source as an LCD backlight or changing the emission intensity of the light source.

When the occurrence of such a predetermined event is detected, the control unit 160 reads out the correction data of the geomagnetic detection value prepared in advance in response to the detected event from the storage unit 152, and the correction data currently in use. To change.

FIG. 13 is a diagram showing an example of correction data. In the example of FIG. 13, the correction data is composed of three correction values corresponding to the detection values in the three directions (X-axis, Y-axis, and Z-axis) of the geomagnetic sensor 158. For example, when the communication process for operating the wireless communication unit 150 is executed, the control unit 160 has the'-1', '0', and'-1' corresponding to the geomagnetic detection values of the X-axis, Y-axis, and Z-axis. The correction value of is read from the storage unit 152. The storage unit 152 stores, for example, such correction data in association with each of a plurality of events. Each correction value of the correction data is determined, for example, by measuring in advance the amount of fluctuation of the geomagnetic field detection value when each event occurs and when it does not occur.

The control unit 160 corrects the detected value of the geomagnetic sensor 158 based on the correction data read from the storage unit 152 (step ST208). That is, the corresponding correction values of the correction data are added to the detection values in the three directions of the geomagnetic sensor. Then, using the corrected geomagnetic detection value, the orientation is calculated by the above-mentioned calculation method (step ST210). The control unit 160 repeats the above-described processes of steps ST204 to ST210 while the navigation process is being executed (step ST212).

When the occurrence of a plurality of events is detected in step ST204, the control unit 160 adds the correction value of the correction data corresponding to the detected event to the geomagnetic detection value in each of the three directions. For example, in the example of FIG. 13, when both communication processing and voice output processing occur, the correction value of the X axis is'-1' +'-1'='-2', and the correction value of the Y axis is. '0' + '0' = '0', the correction value of the Z axis is'-1' + '0' ='-1'.

When detecting the end of a certain event in step ST204, the control unit 160 subtracts the correction value of the correction data corresponding to the ended event from the current value. For example, if the current X-axis, Y-axis, and Z-axis correction values are'-2','-1', and '1' and the communication processing shown in FIG. 13 is completed, the X-axis correction value will be'. -2'-'-1'='-1', Y-axis correction value is'-1'-'0'='-1', Z-axis correction value is '1'-'-1'=' Changed to 2'.

As described above, according to the first example of the directional calculation process shown in FIG. 12, when the directional information is displayed on the display unit 155, a predetermined event that fluctuates the magnetic field inside the mobile phone 100 occurs. (Including the end of the event) is monitored by the control unit 160, and when the occurrence of the predetermined event is detected, the directional information is corrected. Therefore, even if the detection value of the geomagnetic sensor 158 fluctuates due to the occurrence of an event and the accuracy of the orientation information displayed on the display unit 155 deteriorates, the occurrence of the event is detected and the orientation information is corrected. The accuracy of the directional information can be restored. Further, since the directional information is corrected by using the correction data that is determined in advance for each event and stored in the storage unit 152, the directional information can be corrected accurately for each event that occurs.

Next, a second example of the direction calculation process will be described. FIG. 14 is a flowchart illustrating a second example of the orientation calculation process in the mobile phone 100.

The difference between the first example (FIG. 12) and the second example (FIG. 14) is that after detecting the occurrence of a predetermined event, an operation for correcting the directional information is performed to display the display unit 155. The point is that the display unit 155 displays that the accuracy of the directional information displayed on the display unit 155 is low until the directional information of the calculation result is displayed on the display unit 155.

That is, when the control unit 160 detects the occurrence of a predetermined event in step ST204, the control unit 160 causes the display unit 155 to display that the accuracy of the orientation information displayed on the display unit 155 is low (step ST214). For example, when displaying an image of a compass representing the direction, it may be shown that the accuracy of the direction information is low by displaying the movement of the compass swinging left and right. Further, the shape, color, and size of the compass image may be changed, or another image indicating that the orientation accuracy is low may be displayed.

The control unit 160 displays information indicating such a decrease in orientation accuracy while changing the correction value (step ST206), correcting the geomagnetic detection value (step ST208), and calculating the orientation (step ST210). Displayed in part 155. Then, when the corrected directional information is displayed on the display unit 155, the display unit 155 displays that the directional accuracy has been restored (step ST216). For example, when the decrease in directional accuracy is displayed by the movement of swinging the compass image left and right, it may be shown that the accuracy of the azimuth is restored by stopping the left and right swing. When the decrease in orientation accuracy is displayed by changing the shape, color, and size of the compass image, the accuracy may be restored by returning this to the original state. Alternatively, another image indicating that the accuracy of the orientation information has been restored may be displayed.

As described above, according to the second example of the orientation calculation process shown in FIG. 14, when the correction value of the geomagnetic detection value is changed due to the occurrence of a predetermined event (including the end of the event), a new correction is made. It is possible to notify the user that the accuracy of the directional information being displayed is low until the directional recalculation is performed based on the value and the result is displayed on the display unit 155. As a result, the user can correctly grasp whether or not the accuracy of the displayed directional information is low.

Next, a third example of the direction calculation process will be described. FIG. 15 is a flowchart illustrating a third example of the orientation calculation process in the mobile phone 100.

In the orientation calculation processing of the first and second examples described above, the change in the geomagnetic field detection value caused by the occurrence of an event is corrected, but in the third example described below, the geomagnetism according to the open / closed state of the housing is used. Correct the change in the detected value.

The mobile phone 100 includes a component that generates a static magnetic field, such as a magnet used in the speaker 22, unlike the dynamic magnetic field generated for each event as described above. Such a static magnetic field causes a steady error (offset error) of the geomagnetic detection value, and is corrected by an offset error correction process described later. However, when the open / closed state of the housing is changed, the positional relationship of these static magnetic field generation sources with respect to the geomagnetic sensor 158 changes, so that the offset error also changes accordingly. Therefore, in the directional calculation process of the third example, in order to reduce the decrease in accuracy of the directional calculation value due to such a change in the offset error, the offset error correction value obtained by the offset error correction process is set to the open state and the closed state. Keep each separately. Then, when the open / closed state of the housing changes, the correction value used for correcting the offset error is changed accordingly.

When the start of the navigation process is selected by a key input operation or the like in the key input unit 154 (step ST302), the control unit 160 examines the determination result of the open / close determination unit 153 (step ST304). When the open / close determination unit 153 determines that the housing is in the open state, the control unit 160 reads, for example, the offset error correction data in the open state held in a register (not shown) in the control unit 160 (step). ST306), and based on this, the detected value of the geomagnetic sensor 158 is corrected (step ST310). When the open / close determination unit 153 determines that the housing is in the closed state, the control unit 160 reads out the offset error correction data in the closed state held in a register (not shown) in the control unit 160 ( Step ST308), and based on this, correct the detected value of the geomagnetic sensor 158 (step ST310).

The offset error correction data is composed of three correction values corresponding to the geomagnetic detection values in three directions, as shown in FIG. 13, for example. This correction value is frequently acquired at the start of the navigation process or during its execution by the offset error correction process described later, and is written to a predetermined register of the control unit 160 provided for each of the open and closed states. Is done. The offset error correction data stored in the register is rewritten every time the offset error correction process is executed and a new correction value is acquired.

When the detected value of the geomagnetic sensor 158 is corrected, the control unit 160 calculates the direction using the corrected geomagnetic detected value (step ST312).

Next, the control unit 160 acquires the determination result of the open / close determination unit 153 again and examines whether or not there is a change in the open / close state (step ST314). When the change from the closed state to the open state is detected, the control unit 160 returns to step ST306 to read the offset error correction data in the open state, and uses this to repeat the correction of the geomagnetic detection value and the calculation of the direction ( Steps ST310, ST312). When the change from the open state to the closed state is detected, the control unit 160 returns to step ST308 to read the offset error correction data in the closed state, and uses this to repeat the correction of the geomagnetic detection value and the calculation of the direction ( Steps ST310, ST312). If there is no change in the open / closed state, the control unit 160 confirms whether the end of the navigation process is selected (step ST316), and if the navigation process continues, the offset error correction data currently in use is used. The correction of the geomagnetic detection value and the calculation of the direction are repeated (steps ST310 and ST312).

When the end of the navigation process is selected, the control unit 160 saves the offset error correction data in the open state and the closed state held in the register in the storage unit 152 (step ST318). As a result, when the navigation process is performed next time, it becomes possible to quickly calculate the direction using the offset error correction data stored in the storage unit 152.

As described above, according to the third example of the directional calculation process shown in FIG. 15, when the directional information is displayed on the display unit 155, the change in the determination result in the open / close determination unit 153 is monitored, and the change is monitored. When is detected, the orientation information displayed on the display unit 155 is corrected according to the changed state (open state or closed state). That is, when the change is detected, the detection value of the geomagnetic sensor 158 is corrected by a predetermined value corresponding to the state after the change, and the orientation is calculated based on the corrected geomagnetic detection value. Therefore, in the mobile phone 100 having a structure in which the display unit 155 can display the directional information in both the open state and the closed state, the detection value of the geomagnetic sensor 158 fluctuates with the change in the open / closed state and is being displayed. Even when the accuracy of the directional information is lowered, the accuracy of the directional information can be restored by detecting the change in the determination result in the open / close determination unit 153 and correcting the directional information. Further, the offset error correction data in each of the open state and the closed state is separately held in a predetermined register of the control unit 160, and the directional information is corrected by using the appropriate offset error correction data according to the open / closed state. Therefore, the orientation information can be corrected with high accuracy in each state.

In the detection of the change in the open / closed state in step ST314, after the change in the open / closed state is detected based on the determination result of the open / close determination unit 153, the open or closed state after the change continues for a predetermined time, so that the open state is detected. The final determination may be made from the closed state or the change from the closed state to the open state. As a result, it is possible to prevent the offset error correction data from being erroneously changed when the movable mechanism portion 4 unintentionally moves and a change in the open / closed state is detected momentarily.

Next, a fourth example of the direction calculation process will be described. FIG. 16 is a flowchart illustrating a fourth example of the orientation calculation process in the mobile phone 100.

The difference between the third example (FIG. 15) and the fourth example (FIG. 16) is that the open / close determination unit 153 detects a change in the open / closed state, then recalculates the orientation, and the recalculated orientation. The point is that the display unit 155 displays that the accuracy of the directional information displayed on the display unit 155 is low until the information is displayed on the display unit 155.

That is, the control unit 160 detects the change in the open / closed state in step ST314, reads out the offset error correction data according to the changed state in step ST306 or ST308, and then displays the data on the display unit 155. The display unit 155 is displayed to indicate that the accuracy of the directional information is low (step ST320). For example, the control unit 160 swings the image of the compass representing the direction to the left or right, changes the shape, color, size, etc. of the compass, and indicates a decrease in the accuracy of the direction, as in step ST214 of FIG. 14 described above. Information on the decrease in directional accuracy is displayed on the display unit 155 by a method such as displaying another image.

The control unit 160 causes the display unit 155 to display information indicating such a decrease in the accuracy of the orientation while the geomagnetic detection value is corrected (step ST310) and the orientation is calculated (step ST312). Then, when the corrected directional information is displayed on the display unit 155, the display unit 155 displays that the directional accuracy has been restored (step ST322). For example, when the decrease in directional accuracy is displayed by the movement of swinging the compass image left and right, the left and right swing may be stopped. If the decrease in directional accuracy is displayed by changing the shape, color, and size of the compass image, this may be restored to the original state. Alternatively, another image indicating that the accuracy of the orientation information has been restored may be displayed.

As described above, according to the fourth example of the orientation calculation process shown in FIG. 16, when the correction value of the geomagnetic detection value is changed due to the change in the open / closed state of the housing, the orientation is reset by the new correction value. It is possible to notify the user that the accuracy of the directional information being displayed is low until the calculation is performed and the result is displayed on the display unit 155. As a result, the user can correctly grasp whether or not the accuracy of the displayed directional information is low.

Next, a fifth example of the direction calculation process will be described. FIG. 17 is a flowchart illustrating a fifth example of the orientation calculation process in the mobile phone 100.

In the orientation calculation processing of the third and fourth examples described above, the change in the geomagnetic field detection value caused by the change in the open / closed state of the housing is corrected, but in the fifth example described below, the memory card in the memory card unit 159 Corrects changes in the geomagnetic field detection value depending on whether or not the device is installed.

When a component that is easily magnetized, such as a lead frame of a semiconductor integrated device, is used in the memory card, the offset error of the geomagnetic sensor 158 between when the memory card is installed and when it is not installed due to the influence of this magnetism. May change. FIG. 18 is a diagram showing an example of temporal changes in the geomagnetic sensor detection values (X-axis, Y-axis, Z-axis) depending on whether or not a memory card is installed. In the example of FIG. 18, the geomagnetic sensor detection values on the X-axis, Y-axis, and Z-axis change by'-7',' -8', and'-1', respectively. In the directional calculation process of the fifth example, in order to reduce the directional error due to such fluctuation of the geomagnetic sensor detection value, the offset error correction value obtained by the offset error correction process is used when the memory card is installed and when the memory card is not installed. Keep each separately. Then, when the mounting state of the memory card in the housing changes, the correction value used for correcting the offset error is changed accordingly.

When the start of the navigation process is selected by a key input operation or the like in the key input unit 154 (step ST402), the control unit 160 checks the mounting state of the memory card in the memory card unit 159 (step ST404). When it is determined by the signal from the memory card unit 159 that the memory card is installed, the control unit 160 uses, for example, offset error correction data at the time of installing the memory card held in a register (not shown) in the control unit 160. Read (step ST406) and correct the detected value of the geomagnetic sensor 158 based on this (step ST410). When it is determined by the signal from the memory card unit 159 that the memory card is installed, the control unit 160 uses the offset error correction data held in a register (not shown) in the control unit 160 when the memory card is not installed. Is read out (step ST408), and the detected value of the geomagnetic sensor 158 is corrected based on this (step ST410).

The offset error correction data when the memory card is installed and when the memory card is not installed is composed of three correction values corresponding to the geomagnetic detection values in three directions, for example, as shown in FIG. This correction value is frequently acquired at the start of or during the execution of the navigation process by the offset error correction process described later, and is predetermined in the control unit 160 provided for each of the memory card when the memory card is installed and when the memory card is not installed. Is written to the register of. The offset error correction data stored in the register is rewritten every time the offset error correction process is executed and a new correction value is acquired.

When the detected value of the geomagnetic sensor 158 is corrected, the control unit 160 calculates the direction using the corrected geomagnetic detected value (step ST412).

Next, the control unit 160 checks the installed state of the memory card in the memory card unit 159 again, and checks whether there is any change in the installed state (step ST414). When a change from a state in which the memory card is not installed in the memory card unit 159 to a state in which the memory card is installed in the memory card unit 159 is detected, the control unit 160 returns to step ST406 and offsets when the memory card is installed. The error correction data is read out, and the correction of the geomagnetic detection value and the calculation of the direction are repeated using this data (steps ST410 and ST412). When the control unit 160 returns to step ST408 and detects a change from the state in which the memory card is installed in the memory card unit 159 to the state in which the memory card is not installed in the memory card unit 159, the control unit 160 returns to step ST408 when the memory card is not installed. The offset error correction data is read out, and the correction of the geomagnetic detection value and the calculation of the orientation are repeated using this data (steps ST410 and ST412). If there is no change in the installed state of the memory card, the control unit 160 confirms whether the end of the navigation process is selected (step ST416), and if the navigation process continues, the offset error correction data currently in use The correction of the geomagnetic field detection value and the calculation of the orientation are repeated using (steps ST410, ST412).

When the end of the navigation process is selected, the control unit 160 saves the offset error correction data held in the registers when the memory card is installed and when the memory card is not installed in the storage unit 152 (step ST418). As a result, when the navigation process is performed next time, it becomes possible to quickly calculate the direction using the offset error correction data stored in the storage unit 152.

As described above, according to the fifth example of the orientation calculation process shown in FIG. 17, when the orientation information is displayed on the display unit 155, the change in the mounting state of the memory card in the memory card unit 159 is monitored. When the change is detected, the orientation information displayed on the display unit 155 is corrected according to the state after the change (attached or not attached). That is, when a change is detected in the mounting state of the memory card, a predetermined correction corresponding to the changed state is performed on the detected value of the geomagnetic sensor 158, and the orientation is changed based on the corrected geomagnetic detection value. It is calculated. Therefore, even if the detection value of the geomagnetic sensor 158 fluctuates due to a change in the memory card mounting state and the accuracy of the orientation information displayed on the display unit 155 deteriorates, the memory card mounting state in the memory card unit 159 changes. By detecting and correcting the directional information, the accuracy of the directional information can be restored. Further, the offset error correction data in each of the mounted state and the non-mounted state is separately held in a predetermined register of the control unit 160, and the orientation is used by using the appropriate offset error correction data according to the mounted state of the memory card. Since the information of the above is corrected, the direction information can be corrected with high accuracy in each state.

Next, a sixth example of the direction calculation process will be described. FIG. 19 is a flowchart illustrating a sixth example of the orientation calculation process in the mobile phone 100.

The difference between the fifth example (FIG. 17) and the sixth example (FIG. 19) is that the orientation is recalculated after detecting the change in the mounting state of the memory card, and the information of the recalculated orientation is used. The point is that the display unit 155 displays that the accuracy of the orientation information displayed on the display unit 155 is low until the display unit 155 displays the information.

That is, the control unit 160 detects a change in the memory card mounting state in step ST414, and in response to this, reads out offset error correction data according to the changed state in step ST406 or ST408, and then displays the display unit 155. The display unit 155 is displayed to indicate that the accuracy of the displayed orientation information is low (step ST420). For example, the control unit 160 swings the image of the compass representing the direction to the left or right, changes the shape, color, size, etc. of the compass, and indicates a decrease in the accuracy of the direction, as in step ST214 of FIG. 14 described above. Information on the decrease in directional accuracy is displayed on the display unit 155 by a method such as displaying another image.

The control unit 160 causes the display unit 155 to display information indicating such a decrease in the accuracy of the orientation while the geomagnetic detection value is corrected (step ST410) and the orientation is calculated (step ST412). Then, when the corrected directional information is displayed on the display unit 155, the display unit 155 displays that the directional accuracy has been restored (step ST422). For example, when the decrease in directional accuracy is displayed by the movement of swinging the compass image left and right, the left and right swing may be stopped. If the decrease in directional accuracy is displayed by changing the shape, color, and size of the compass image, this may be restored to the original state. Alternatively, another image indicating that the accuracy of the orientation information has been restored may be displayed.

As described above, according to the sixth example of the orientation calculation process shown in FIG. 19, when the correction value of the geomagnetic detection value is changed due to the change in the mounting state of the memory card, the orientation is reset by the new correction value. It is possible to notify the user that the accuracy of the directional information being displayed is low until the calculation is performed and the result is displayed on the display unit 155. As a result, the user can correctly grasp whether or not the accuracy of the displayed directional information is low.

Next, the offset error correction processing will be described.

The offset error correction process is a process for correcting an error in a steady geomagnetic detection value caused by a magnetic field generation source inside the mobile phone 100. The static magnetic field generated inside the mobile phone 100 causes a steady error in the detected value of the geomagnetic sensor 158 regardless of the orientation of the mobile phone 100. On the other hand, the detected value of the geomagnetism itself changes according to the direction in which the mobile phone 100 is pointed. Therefore, for example, by detecting the geomagnetism while rotating the mobile phone 100 and obtaining the trajectory of the geomagnetic vector according to the rotation of the mobile phone 100, the offset error included in the detection value of the geomagnetic sensor 158 can be easily calculated. Can be done.

The control unit 160 causes the display unit 155 to display an instruction prompting the user to rotate the mobile phone 100, for example, when starting the navigation process. When the user rotates the mobile phone 100 according to this instruction, the control unit 160 acquires a plurality of detected values of the geomagnetic sensor 158 during the rotation. Then, the offset error is calculated from the vector locus of the acquired geomagnetic detection value and subtracted from the detection value of the geomagnetic sensor 158. As a result, a geomagnetic detection value with the offset error corrected can be obtained. The control unit 160 stores the offset error calculated by the offset error correction process as described above in a predetermined register of the control unit 160 as offset error correction data.

Further, the control unit 160 performs the offset error correction process described above at regular intervals, for example, even while the navigation process is being executed.

Further, as described below, the control unit 160 also performs offset error correction processing to correct the geomagnetic detection value even when the detection value of the geomagnetic sensor 158 becomes a predetermined abnormal state such as overflow.

FIG. 20 is a flowchart illustrating a first example of offset error correction processing when an abnormal state occurs in the geomagnetic field detection value.

When the start of the navigation process is selected by a key input operation or the like in the key input unit 154 (step ST502), the control unit 160 checks whether the detected value of the geomagnetic sensor 158 is in a predetermined abnormal state (step ST504). Here, the predetermined abnormal state is, for example, any one of the 8-bit detection values represented by integer values from '0' to '255' (that is, the geomagnetic detection values of the X-axis, Y-axis, and Z-axis). One of them) has overflowed, and its value is the maximum value '255' or the minimum value '0'. Further, when a normal range having an upper limit value and a lower limit value is specified, an abnormal state may be established when any one of the geomagnetic field detection values is out of this normal range.

When the control unit 160 detects such an abnormal state of the geomagnetic detection value, the control unit 160 measures the duration of the abnormal state from the time of the detection (step ST506). Then, when the abnormal state lasts for a predetermined time (for example, 5 seconds), the control unit 160 determines that an offset error has occurred due to magnetism of the mobile phone 100 or the like, and executes the above-mentioned offset error correction process (step ST510). ).

After the offset error correction process, the control unit 160 checks whether the end of the navigation process is selected, and if it is confirmed that the process continues, repeats the process of steps ST504 to ST510 described above (step ST512). If the abnormal state of the geomagnetic detection value is not detected in step ST504, or if it is determined in step ST508 that the abnormal state of all the detected values has been resolved within a predetermined time, the continuation of the navigation process is confirmed in the same manner. Then, the processing of steps ST504 to ST510 is repeated (step ST512).

As described above, according to the first example of the offset error correction processing shown in FIG. 20, when the orientation information is displayed on the display unit 155, the detected value of the geomagnetic sensor 158 becomes a predetermined abnormal state. If this abnormal state continues for a predetermined time, the directional information is corrected. That is, when any one (or a plurality) of the detected values of the geomagnetism in the three directions becomes a predetermined abnormal state and this abnormal state continues for a predetermined time, the process of detecting and correcting the offset error of the geomagnetic sensor 158. (Offset error correction processing) is performed, and the orientation is recalculated based on the corrected geomagnetic detection value. Therefore, by monitoring the abnormality of the detection value of the geomagnetic sensor 158, the occurrence of an offset error due to magnetization of the mobile phone 100 is detected and appropriate correction is performed, so that the accuracy of the orientation information is reduced due to the offset error. It can be suppressed.

Further, according to the process of FIG. 20, when the geomagnetic detection value continues for a predetermined time or more and becomes a predetermined abnormal state, the offset error correction process is performed. Therefore, for example, a temporary abnormal state of the geomagnetic field detection value caused by the influence of an external magnetic field generated from a building or a train is mistakenly determined as an offset error caused by magnetization of the mobile phone 100, and an inappropriate offset is obtained. It is possible to reduce the case where the error correction process is executed.

FIG. 21 is a diagram showing an example of an abnormal state of the geomagnetic field detection value caused by the influence of an external magnetic field. In the example of the figure, the geomagnetic detection value in the Z-axis direction sticks to '0' for a time of 3 to 4 seconds. If the offset error correction process is executed when such an abnormality due to a temporary external magnetic field occurs, the offset error cannot be calculated correctly, so the geomagnetic detection value is corrected with an incorrect correction value. As a result, the calculation result of the orientation becomes inaccurate. The inaccurate azimuth state continues at least until the next offset error correction process.

As shown in FIG. 21, the abnormal state of the geomagnetic field detection value due to the influence of the external magnetic field is usually transient within a few seconds, and often returns to the normal state within, for example, 5 seconds. Therefore, as in the process of FIG. 20, the abnormal state caused by the influence of the external magnetic field and the offset error are discriminated according to whether or not the abnormal state lasts for a predetermined time or longer, and the offset error correction process is performed according to the discriminant result. By controlling the execution of the correction process, it is possible to effectively prevent the improper execution of the correction process.

Next, a second example of offset error correction processing will be described. FIG. 22 is a flowchart illustrating a second example of offset error correction processing in the mobile phone 100.

The difference between the first example (FIG. 20) and the second example (FIG. 22) is that the display unit 155 displays that the accuracy of the azimuth information is low while the azimuth information is being corrected. It is in.

That is, after determining in step ST508 that the abnormality of the geomagnetic field detection value has continued for a predetermined time or longer, the control unit 160 causes the display unit 155 to display that the accuracy of the orientation information displayed on the display unit 155 is low (step). ST514). Similar to the control unit 160, for example, step ST214 of FIG. 14 described above, the image of the compass indicating the orientation is shaken left and right, the shape, color, size, etc. of the compass are changed, and the accuracy of the orientation is reduced. Information on the decrease in directional accuracy is displayed on the display unit 155 by a method such as displaying the image of.

The control unit 160 causes the display unit 155 to display information indicating such a decrease in directional accuracy while performing the offset error correction process (step ST510). Then, when displaying the orientation information recalculated based on the corrected geomagnetic detection value on the display unit 155, the display unit 155 displays that the accuracy of the orientation has been restored (step ST516). For example, when the decrease in directional accuracy is displayed by the movement of swinging the compass image left and right, the left and right swing may be stopped. If the decrease in directional accuracy is displayed by changing the shape, color, and size of the compass image, this may be restored to the original state. Alternatively, another image indicating that the accuracy of the orientation information has been restored may be displayed.

As described above, according to the second example of the offset error correction processing shown in FIG. 22, the orientation displayed on the display unit 155 while the orientation information is corrected due to the abnormality of the geomagnetic detection value. It is possible to notify the user that the accuracy of the information is low. As a result, the user can correctly grasp whether or not the accuracy of the displayed directional information is low.

Next, a third example of offset error correction processing will be described. FIG. 23 is a flowchart illustrating a third example of the offset error correction process in the mobile phone 100.

The difference between the second example (Fig. 22) and the third example (Fig. 23) described above is that the map display is fixed from the heading-up display to the north-up display while the directional information is being corrected, and the directional display is fixed. When the correction of the information in is completed, the heading-up display is restarted.

That is, after determining in step ST508 that the abnormality of the geomagnetic field detection value has continued for a predetermined time or longer, the control unit 160 fixes the map display from the heading-up display to the north-up display (step ST518), and offset error correction processing (step ST518). While performing step ST510), the north-up display is maintained. Then, when the orientation is recalculated based on the corrected geomagnetic detection value, the north-up display is canceled and the heading-up display is restarted (step ST520).

As described above, also in the third example of the offset error correction processing shown in FIG. 23, the display unit is fixed to the north-up display while the directional information is corrected due to the abnormality of the geomagnetic detection value. It is possible to notify the user that the accuracy of the directional information displayed on the 155 is low. As a result, the user can correctly grasp whether or not the accuracy of the displayed directional information is low.

Next, the processing when an error occurs in the detected value of the geomagnetic sensor 158 due to the influence of the external magnetic field and the accuracy of the directional information is lowered will be described.

In general, since buildings and trains contain many magnetic field sources, the detection value of the geomagnetic sensor 158 has a large error due to the influence of the external magnetic fields generated by these magnetic field sources inside and around the building and the train. If the offset error correction process is executed in such an area, an erroneous offset error will be calculated. Therefore, even after leaving the area, it is inaccurate until the offset error correction process is performed again. The orientation information remains displayed on the display unit 155. Therefore, in the processing described below, the offset error correction processing is prohibited when it is detected that the detection value of the geomagnetic sensor 158 has entered an area where an error occurs due to the influence of an external magnetic field or the like. In addition, the display unit 155 is displayed to indicate that the accuracy of the directional information is reduced so that the user can determine whether or not the directional information should be referred to.

FIG. 24 is a flowchart illustrating the first example of processing when an error occurs in the geomagnetic field detection value due to the influence of an external magnetic field.

When the start of navigation processing is selected by a key input operation or the like in the key input unit 154 (step ST602), the control unit 160 determines whether the level of the GPS signal received by the GPS signal reception unit 151 is lower than a predetermined value. Check (step ST604).

Normally, GPS signal levels are very low to unreceivable levels when the mobile phone 100 enters the interior of a building. In this example, this property is used to determine whether or not the mobile phone 100 is inside the building.

When it detects that the GPS signal is lower than the predetermined value, the control unit 160 determines that the mobile phone 100 has entered the inside of the building and prohibits the execution of the offset error correction process described above (step ST606). For example, when the correction process is repeated at regular time intervals, the correction process is not performed even after the lapse of the fixed time. Further, in this case, the control unit 160 causes the display unit 155 to display that the accuracy of the directional information has deteriorated (step ST608). For example, as in step ST214 of FIG. 14 described above, the image of the compass showing the orientation can be shaken left and right, the shape, color, size, etc. of the compass can be changed, and another image showing the decrease in the accuracy of the orientation can be displayed. Information on the decrease in directional accuracy is displayed on the display unit 155 by a method such as displaying.

On the other hand, when it is detected that the GPS signal is higher than the predetermined value, the control unit 160 determines that the mobile phone 100 is not inside the building, and the execution of the offset error correction processing described above is prohibited. If so, remove this prohibition (step ST610). Further, in this case, the control unit 160 causes the display unit 155 to display that the accuracy of the directional information has been restored (step ST612). For example, when the decrease in directional accuracy is displayed by the movement of swinging the compass image left and right, the left and right swing may be stopped. If a decrease in orientation accuracy is displayed by changing the shape, color, or size of the compass image, this may be restored to the original state. Alternatively, another image indicating that the accuracy of the orientation information has been restored may be displayed.

After step ST608 or ST612, the control unit 160 checks whether the end of the navigation process is selected, and if it is confirmed that the process continues, repeats the process after step ST604 described above (step ST614).

As described above, according to the first example of processing when an error occurs in the geomagnetic field detection value due to the influence of the external magnetic field (FIG. 24), GPS signal reception is performed when the orientation information is displayed on the display unit 155. When the level of the GPS signal received by the unit 151 is monitored and it is detected that this level is lower than a predetermined value, it is determined that the mobile phone 100 is inside the building, and the display unit 155 displays. Information indicating that the accuracy of the orientation information is low is displayed on the display unit 155. As a result, the user can correctly grasp whether or not the accuracy of the displayed directional information is low. For example, if the accuracy of the directional information is low, the directional can be grasped by comparing the information displayed on the map with the surrounding landscape without referring to the directional displayed on the screen. Since it becomes clear to the user that a guess should be made, the usability of the navigation function can be improved.

In addition, since the execution of offset error correction processing is prohibited in inappropriate areas where the offset error cannot be calculated accurately due to the influence of the external magnetic field, such as inside a building, the display of inaccurate orientation is displayed for a long time. It is possible to reduce the number of cases that are displayed in part 155.

Next, a second example of processing when an error occurs in the geomagnetic field detection value due to the influence of an external magnetic field will be described with reference to the flowchart shown in FIG.

The difference between the first example (Fig. 24) and the second example (Fig. 25) is that the map display is displayed from the heading-up display to the north-up display when it detects that the GPS signal is lower than the predetermined value. When it is detected that the GPS signal is higher than the predetermined value, the heading-up display is restarted.

That is, when the control unit 160 detects that the GPS signal is lower than the predetermined value in step ST604, the offset error correction process is prohibited (step ST606), and the map display is changed from the heading-up display to the north-up display. Fix (step ST616). When it is detected in step ST604 that the GPS signal is higher than the predetermined value, the prohibition of offset error correction processing is released (step ST610), the north-up display is canceled, and the heading-up display is restarted (step ST610). Step ST618).

As described above, according to the processing of the second example shown in FIG. 25, the map display is fixed to the north-up display in the area where the accuracy of the directional information is lowered due to the influence of the external magnetic field such as the inside of the building. As a result, it is possible to notify the user that the accuracy of the orientation information displayed on the display unit 155 is low. As a result, the user can correctly grasp whether or not the accuracy of the displayed directional information is low.

Next, a third example of processing when an error occurs in the geomagnetic field detection value due to the influence of an external magnetic field will be described with reference to the flowchart shown in FIG.

The difference between the third example (Fig. 26) and the second example (Fig. 25) described above is that when it is detected that the GPS signal is lower than the predetermined value, the orientation calculation process and the operation of the geomagnetic sensor 158 are performed. When it is stopped and it is detected that the GPS signal becomes higher than a predetermined value, these operations are restarted.

That is, when the control unit 160 detects that the GPS signal is lower than the predetermined value in step ST604, the control unit 160 fixes the map display from the heading-up display to the north-up display (step ST616), and also performs the direction calculation process and the direction calculation process. Stop the operation of the geomagnetic sensor 158 (step ST620). When it is detected in step ST604 that the GPS signal is higher than the predetermined value, the north-up display is canceled and the heading-up display is restarted (step ST618), and the direction calculation process and the operation of the geomagnetic sensor 158 are performed. Resume (step ST622).

Originally, the inside of a building where it is difficult to receive GPS signals is an environment that is easily affected by an external magnetic field, but according to the processing of the third example shown in FIG. 26 described above, the mobile phone 100 is in such an environment. Since the operation of the geomagnetic sensor 158 is stopped by detecting whether or not it is present according to the level of the GPS signal, it is possible to suppress the supply of unnecessary power to the unused circuit and reduce the power consumption.

Next, a fourth example of processing when an error occurs in the geomagnetic field detection value due to the influence of an external magnetic field will be described with reference to the flowchart shown in FIG. 27.

The difference between the third example (Fig. 26) and the fourth example (Fig. 27) is that when it detects that the GPS signal is higher than the predetermined value, the calculated directional value stabilizes before heading up. It is to restart the display.

That is, after the control unit 160 detects that the GPS signal has become higher than the predetermined value in step ST604 and restarts the directional calculation process and the operation of the geomagnetic sensor 158 (step ST622), the directional calculated value is stable. Determine if it has been done (step ST624). For example, the control unit 160 determines that the calculated value of the direction is stable when the fluctuation range of the calculation result of the direction in the predetermined time is within the predetermined range. Then, after determining that the calculated directional value is stable, the north-up display is canceled and the heading-up display is restarted (step ST618).

As described above, according to the processing of the fourth example shown in FIG. 27, when the signal level of the GPS signal becomes higher than the predetermined value and it is determined that the mobile phone 100 has come out from the inside of a building or the like, the orientation is calculated. The heading-up display is restarted after the value is confirmed to be stable. Therefore, for example, it is possible to prevent the display unit 155 from displaying the low-precision directional information in a state where the geomagnetic field detection value fluctuates greatly due to the magnetic field from the building immediately after going out of the building.

Next, a fifth example of processing when an error occurs in the geomagnetic field detection value due to the influence of an external magnetic field will be described with reference to the flowchart shown in FIG. 28.

In the processing of the first to fourth examples described above (FIGS. 24 to 27), whether or not the mobile phone 100 is inside the building based on the reception level of the GPS signal, that is, the geomagnetism due to the influence of the external magnetic field. It is judged whether or not it is in an area where an error is likely to occur in the detection of. In the processing of the fifth example (FIG. 28) described below, the current location of the mobile phone 100 is included in the accuracy-reduced area where the accuracy of the detected value of the magnetic sensor 158 is reduced based on the information registered in the storage unit 152 in advance. It is determined whether or not the information is included, and if it is determined that the information is included, the offset error correction processing is prohibited. In addition, the display unit 155 is displayed to indicate that the accuracy of the directional information is reduced so that the user can determine whether or not the directional information should be referred to.

First, when the start of the navigation process is selected by the key input operation in the key input unit 154 (step ST702), is the control unit 160 included in the accuracy-reduced area where the current location of the terminal is registered in the storage unit 152? Determine if not (step ST704).

The information on the reduced accuracy area registered in the storage unit 152 is, for example, the identification number of the map sent from the navigation server device 402 and the information on the coordinates of the reduced accuracy area on this map (for example, a map according to the range of coordinates). It is composed of the above information indicating the area of reduced accuracy, etc.). The control unit 160 first searches for the information of the same identification number as the currently displayed map from the information of the accuracy-reduced area registered in the storage unit 152. If the information of the same identification number exists as a result of the search, it is further determined whether or not the current location of the mobile phone 100 is included in the coordinate range of the accuracy-reduced area on the map indicated by the coordinate information. When the current location is included in this coordinate range, the control unit 160 determines that the current location of the mobile phone 100 is included in the accuracy-reduced area.

When it is determined that the current location is included in the accuracy-reduced area, the control unit 160 prohibits the execution of the offset error correction process described above (step ST706). For example, when the correction process is repeated at regular time intervals, the correction process is not performed even after the lapse of the fixed time. Further, in this case, the control unit 160 causes the display unit 155 to display that the accuracy of the directional information has deteriorated (step ST708). For example, as in step ST214 of FIG. 14 described above, the image of the compass showing the orientation can be shaken left and right, the shape, color, size, etc. of the compass can be changed, and another image showing the decrease in the accuracy of the orientation can be displayed. Information on the decrease in directional accuracy is displayed on the display unit 155 by a method such as displaying.

On the other hand, when it is determined that the current location is outside the accuracy-reduced area, the control unit 160 releases the prohibition if the execution of the offset error correction processing described above is prohibited (step ST710). Further, in this case, the control unit 160 causes the display unit 155 to display that the accuracy of the directional information has been restored (step ST712). For example, when the decrease in directional accuracy is displayed by the movement of swinging the compass image left and right, the left and right swing may be stopped. If a decrease in orientation accuracy is displayed by changing the shape, color, or size of the compass image, this may be restored to the original state. Alternatively, another image indicating that the accuracy of the orientation information has been restored may be displayed.

After step ST708 or ST712, the control unit 160 checks whether the end of the navigation process is selected, and if it is confirmed that the process continues, repeats the process after step ST704 described above (step ST714).

As described above, according to the fifth example (FIG. 28) of the process when the geomagnetic field detection value has an error due to the influence of the external magnetic field, when the orientation information is displayed on the display unit 155, the mobile phone 100 It is determined whether or not the current location of is included in the accuracy-reduced area registered in the storage unit 152. As a result of this determination, when it is determined that the current location is included in the accuracy-reduced area, the display unit 155 displays information indicating that the accuracy of the orientation information on the display unit 155 is low. As a result, the user can correctly grasp whether or not the accuracy of the displayed directional information is low, so that the ease of use of the navigation function can be improved.

In addition, since the execution of the offset error correction processing is prohibited in the area where the accuracy is lowered where the offset error cannot be calculated accurately due to the influence of the external magnetic field, the display unit 155 displays the inaccurate direction for a long time. It is possible to reduce the number of cases that end up.

Next, a sixth example of processing when an error occurs in the geomagnetic field detection value due to the influence of an external magnetic field will be described with reference to the flowchart shown in FIG.

The difference between the sixth example (Fig. 29) and the fifth example (Fig. 28) described above is that the map display is fixed from the heading-up display to the north-up display when it is determined that the current location is included in the area with reduced accuracy. However, when it is determined that the current location is out of the area where the accuracy is reduced, the heading-up display is restarted.

That is, when the control unit 160 determines in step ST704 that the current location of the mobile phone 100 is included in the accuracy-reduced area, the offset error correction process is prohibited (step ST706), and the map display is north-up from the heading-up display. Fix to display (step ST716). If it is determined in step ST704 that the current location is out of the accuracy-reduced area, the prohibition of offset error correction processing is released (step ST710), the north-up display is canceled, and the heading-up display is restarted (step ST718). ..

As described above, according to the processing of the sixth example shown in FIG. 29, the map display is fixed to the north-up display in the area where the accuracy of the directional information is lowered due to the influence of the external magnetic field such as the inside of the building. As a result, it is possible to notify the user that the accuracy of the orientation information displayed on the display unit 155 is low. As a result, the user can correctly grasp whether or not the accuracy of the displayed directional information is low.

Next, a seventh example of processing when an error occurs in the geomagnetic field detection value due to the influence of an external magnetic field will be described with reference to the flowchart shown in FIG.

The difference between the sixth example (FIG. 29) and the seventh example (FIG. 30) is that the orientation calculation process is performed when it is determined that the mobile phone 100 has entered the accuracy-reduced area based on the information in the storage unit 152. Further, the operation of the geomagnetic sensor 158 is stopped, and when it is determined that the mobile phone 100 has come out of the area where the accuracy is deteriorated, these operations are restarted.

That is, when the control unit 160 determines in step ST704 that the current location of the mobile phone 100 is included in the area with reduced accuracy, the control unit 160 fixes the map display from the heading-up display to the north-up display (step ST716) and calculates the direction. The processing and the operation of the geomagnetic sensor 158 are stopped (step ST720). If it is determined in step ST704 that the current location is out of the area where the accuracy is reduced, the north-up display is canceled and the heading-up display is restarted (step ST718), and the direction calculation process and the operation of the geomagnetic sensor 158 are restarted (step ST718). Step ST722).

As described above, according to the processing of the eighth example shown in FIG. 30, the operation of the geomagnetic sensor 158 is stopped in the area where the accuracy of the directional information is lowered due to the influence of the external magnetic field, which is wasteful to the unused circuit. It is possible to reduce the power consumption by suppressing the supply of electric power.

Next, an eighth example of processing when an error occurs in the geomagnetic field detection value due to the influence of an external magnetic field will be described with reference to the flowchart shown in FIG.

The difference between the 8th example (Fig. 31) and the 7th example (Fig. 30) described above is that when it is determined that the mobile phone 100 has come out of the area where the accuracy is reduced, the heading is increased after the calculated directional value stabilizes. It is to restart the display.

That is, the control unit 160 determines in step ST704 that the current location of the mobile phone 100 is outside the area where the accuracy is reduced, and after resuming the directional calculation process and the operation of the geomagnetic sensor 158 (step ST722), the directional calculation is performed. Determine if the value is stable (step ST724). For example, the control unit 160 determines that the calculated value of the direction is stable when the fluctuation range of the calculation result of the direction in the predetermined time is within the predetermined range. Then, after determining that the calculated directional value is stable, the north-up display is canceled and the heading-up display is restarted (step ST718).

As described above, according to the processing of the eighth example shown in FIG. 31, when it is determined that the current location of the mobile phone 100 is outside the area where the accuracy is reduced, the heading is performed after confirming that the calculated directional value is stable. The up display is resumed. Therefore, for example, immediately after moving out of the area where the accuracy is lowered, if the fluctuation of the geomagnetic field detection value due to the magnetic field from the building or the like remains, it is possible to prevent the information of the low accuracy orientation from being displayed on the display unit 155. ..

Next, in the processes of the fifth to eighth examples described above (FIGS. 28 to 31), the process of registering the accuracy-reduced area in the storage unit 152 will be described with reference to the flowchart of FIG. 32.

When the start of the navigation process is selected by a key input operation or the like in the key input unit 154 (step ST732), the control unit 160 checks whether the detected value of the geomagnetic sensor 158 is in a predetermined abnormal state (step ST734). Here, the predetermined abnormal state is the same as that described in the offset error correction process of FIG. 20, for example. That is, there is an overflow in any one of the 8-bit detection values represented by integer values from '0' to '255', or any one of the geomagnetic detection values is out of the predetermined normal range. The current state is detected as an abnormal state.

When the control unit 160 detects such an abnormal state of the geomagnetic detection value, the control unit 160 measures the duration of the abnormal state from the time of the detection (step ST736). Then, when the abnormal state ends within a predetermined time (for example, 5 seconds), the control unit 160 determines that an error has occurred in the geomagnetic detection location due to the external magnetic field (step ST738), and stores the current location as the accuracy-reduced region 152. Register with (step ST740).

The registration of the area with reduced accuracy in the storage unit 152 includes the identification number of the map displayed when the abnormality of the geomagnetic detection value is detected and the information of the coordinates on the map where the abnormality occurs (for example, the abnormality occurrence point). It is performed by associating it with the coordinate range of an area of several meters square, etc.) and storing it in a predetermined data table for registering an area with reduced accuracy assigned to the storage unit 152.

An upper limit may be set for the number of areas with reduced accuracy registered in the storage unit 152. In this case, when the number of accuracy-reduced areas registered in the storage unit 152 reaches this upper limit, the control unit 160 uses the registered accuracy-reduced area information when registering a new accuracy-reduced area. You may delete the oldest information. As a result, it is possible to prevent the storage area of the storage unit 152 from being consumed endlessly by the registered information of the accuracy-reduced area, and it is possible to improve the reliability of the information of the accuracy-reduced area by leaving the latest information.

After registering the accuracy-reduced area in the storage unit 152, the control unit 160 checks whether the end of the navigation process is selected (step ST742), and if it is confirmed that the process continues, the above-mentioned steps ST734 to ST740 Repeat the process of. If the abnormal state of the geomagnetic field detection value is not detected in step ST734, or if it is determined in step ST738 that the abnormal state of the geomagnetic field detection value continues for a predetermined time or longer, the continuation of the navigation process is confirmed in the same manner. The processing of steps ST734 to ST740 is repeated.

Although preferred embodiments of the present invention have been described so far, the present invention is not limited to the above-described embodiments, and includes various variations.

In the above-described embodiment, the first to sixth examples are used as the orientation calculation process, the first to third examples are used as the offset error correction process, and the first to third examples are used when an error occurs in the geomagnetic field detection value due to the influence of the external magnetic field. Although the eighth example is shown, the embodiment of the present invention includes a form in which at least a part of these processing examples is arbitrarily combined.

In the above-described embodiment, an example in which the geomagnetic sensor 158 detects geomagnetism in three directions is shown, but the present invention is not limited to this, and for example, two directions may be used.

In the above-described embodiment, for example, in step ST208 of FIG. 14, an example is shown in which the display unit 155 displays that the accuracy of the directional information is lowered, but the present invention is not limited to this, and for example, this display. If the directional information is being corrected while the above is being performed, the display unit 155 may display that the correction is in progress. Alternatively, the display unit 155 may display information indicating both the accuracy is being reduced and the correction is being performed.

Further, instead of displaying the information such as the accuracy is being lowered or the correction is being performed, the display of the orientation information may be simply stopped. In this case, when the directional correction is completed (or when the area is out of the area where the accuracy is reduced), the user may be shown that the accuracy of the directional information has been restored by restarting the display of the directional information. ..

In steps ST616 and ST618 of FIGS. 26 and 27, the north-up display is fixed and released, but the present invention is not limited to this. May be displayed.

In steps ST716 and ST718 in FIGS. 30 and 31, the north-up display is fixed and released, but the present invention is not limited to this, and for example, as in steps ST708 and ST712 in FIG. May be displayed.

In the fifth to eighth examples (FIGS. 28 to 31), which are the processes when the geomagnetic field detection value has an error due to the influence of the external magnetic field, the information of the area where the accuracy is deteriorated is acquired from the data table of the storage unit 152. However, the present invention is not limited to this, and may be obtained from a server device connected via, for example, the wireless communication unit 150. That is, the control unit 160 acquires information indicating whether or not the current location of the mobile phone 100 is included in the accuracy-reduced area from a predetermined server device via the wireless communication unit 150, and the current location is accurate in the acquired information. If it is shown to be included in the reduced area, the offset error correction process may be prohibited.

In the above-described embodiment, the mobile phone 100 performs map rotation processing (for example, heading-up display), but the present invention is not limited to this, and for example, the mobile phone 100 determines the direction of map display with respect to the navigation server device 402. The map information may be specified and requested, and the navigation server device 402 may generate map information in a direction corresponding to the request from the mobile phone 100 and provide the map information to the mobile phone 100. That is, the control unit 160 may perform a process of acquiring the image information of the map according to the orientation calculated based on the geomagnetic detection value from the navigation server device 402 and displaying it on the display unit 155. Then, during this process, if a decrease in the detection accuracy of the geomagnetic detection value is detected, for example, because the GPS signal level becomes lower than a predetermined value, the control unit 160 is preset regardless of the calculated orientation. The image information of the map of the direction may be requested from the navigation server device 402, acquired, and displayed on the display unit 155.

In the above-described embodiment, the GPS server device 401 performs the position calculation process according to the GPS signal, but the present invention is not limited to this, and the mobile phone 100 may perform the calculation to obtain the position from the GPS signal.

In the above-described embodiment, the map information is acquired from the navigation server device 402, but the present invention is not limited to this, and the map information may be stored in the internal storage device of the mobile phone 100.

In the above-described embodiment, the processing of the control unit 160 is executed by the computer based on the program, but at least a part of these processing can be executed by the hardware without the computer. .. On the contrary, at least a part of the processing in the units other than the control unit 160 may be executed in the computer of the control unit 160.

Further, the mobile communication terminal of the present invention is not limited to a mobile phone. For example, the present invention can be widely applied to a portable terminal device having a communication function such as a PDA (personal digital assistants).

<figref num="1">It is a block diagram which shows the configuration example of the system for acquiring the information of the geographical position and the map in the mobile phone which concerns on embodiment of this invention.</figref><figref num="2">It is a perspective view of the mobile phone in an open state.</figref><figref num="3">It is a perspective view from one side of the mobile phone in a closed state.</figref><figref num="4">It is a perspective view from the other side of the mobile phone in the closed state.</figref><figref num="5">It is a perspective view which shows the board mounting state in the board mounting housing.</figref><figref num="6">It is a block diagram which shows the structural example of the mobile phone which concerns on embodiment of this invention.</figref><figref num="7">It is a flowchart which illustrates an example of GPS signal reception processing in a mobile phone.</figref><figref num="8">It is a flowchart which illustrates an example of the navigation process in a mobile phone.</figref><figref num="9">It is a figure which shows an example of the map information transmitted from the navigation server device.</figref><figref num="10">It is a flowchart which illustrates an example of the rotation processing of the display image in a mobile phone.</figref><figref num="11">It is a figure for demonstrating the calculation method of the azimuth angle.</figref><figref num="12">It is a flowchart which illustrates the 1st example of the direction calculation process in a mobile phone.</figref><figref num="13">It is a figure which shows an example of the correction data.</figref><figref num="14">It is the flowchart which illustrated the second example of the direction calculation processing in a mobile phone.</figref><figref num="15">It is a flowchart which illustrates the 3rd example of the direction calculation process in a mobile phone.</figref><figref num="16">It is a flowchart which illustrates the 4th example of the direction calculation process in a mobile phone.</figref><figref num="17">It is a flowchart which illustrates the 5th example of the direction calculation process in a mobile phone.</figref><figref num="18">It is a figure which shows an example of the temporal change of the geomagnetic sensor detection value depending on whether or not a memory card is attached.</figref><figref num="19">It is the flowchart which illustrated the sixth example of the direction calculation processing in a mobile phone.</figref><figref num="20">It is the flowchart which illustrated the first example of the offset error correction processing when the abnormal state occurred in the geomagnetic detection value.</figref><figref num="21">It is a figure which shows an example of the abnormal state of the geomagnetic field detection value caused by the influence of an external magnetic field.</figref><figref num="22">It is the flowchart which illustrated the second example of the offset error correction processing in a mobile phone.</figref><figref num="23">It is a flowchart which illustrates the 3rd example of the offset error correction processing in a mobile phone.</figref><figref num="24">It is the flowchart which illustrated the first example of the process in the case where an error occurs in the geomagnetic field detection value due to the influence of an external magnetic field.</figref><figref num="25">It is the flowchart which illustrated the second example of the process in the case where an error occurs in the geomagnetic field detection value due to the influence of an external magnetic field.</figref><figref num="26">It is the flowchart which illustrated the third example of the process in the case where an error occurs in the geomagnetic field detection value due to the influence of an external magnetic field.</figref><figref num="27">It is a flowchart which illustrated the 4th example of the process in the case where an error occurs in the geomagnetic field detection value due to the influence of an external magnetic field.</figref><figref num="28">It is the flowchart which illustrated the 5th example of the process in the case where an error occurs in the geomagnetic field detection value by the influence of an external magnetic field.</figref><figref num="29">It is the flowchart which illustrated the sixth example of the process in the case where an error occurs in the geomagnetic field detection value due to the influence of an external magnetic field.</figref><figref num="30">It is the flowchart which illustrated the 7th example of the process in the case where an error occurs in the geomagnetic field detection value by the influence of an external magnetic field.</figref><figref num="31">It is the flowchart which illustrated the 8th example of the process in the case where an error occurs in the geomagnetic field detection value by the influence of an external magnetic field.</figref><figref num="32">FIG. 5 is a flowchart illustrating an example of a process of registering an accuracy-reduced area in the storage unit in the processes shown in FIGS. 28 to 31.</figref>

Code description

2 ... 1st housing, 3 ... 2nd housing, 4 ... Movable mechanism, 21 ... Display panel, 100 ... Mobile phone, 200 ... GPS satellite, 300. .. Base station, 401 ... GPS server device, 402 ... Navigation server device, 150 ... Wireless communication unit, 151 ... GPS signal receiver, 152 ... Storage unit, 153 ... Open / close Judgment unit, 154 ... key input unit, 155 ... display unit, 156 ... sound processing unit, 157 ... imaging unit, 158 ... geomagnetic sensor, 159 ... memory card unit, 160. .. Control unit.