Symbol reading device, and program

The present invention relates to a symbol reader and a program.

Symbols are widely used to identify a variety of information. Barcodes are symbols that represent numerical information in a one-dimensional graphic representation according to regulations, and recently, symbols called two-dimensional codes that have information in both the vertical and horizontal directions have begun to spread. A symbol reading device such as a handy terminal (mobile terminal for business use) reads a symbol content by capturing a subject including the symbol with an imaging device such as a camera and analyzing the captured image with a decoding engine.

When capturing a bar code or two-dimensional code symbol with a symbol reader equipped with an imaging device such as a digital camera to extract an ID, what composition and distance is suitable for capturing the symbol? Hard to understand. Conventionally, in a digital camera having a seamless focus adjustment function, the following methods exist as means for selecting an optimum focus position for shooting a subject such as a barcode. For example, the distance to an object can be measured directly by using a distance measurement sensor using a PSD (Position Sensitive Detector) or a phase difference difference method using two sets of linear image sensors, or distance measurement using laser irradiation. There is a method of measuring the distance by taking a method and moving the lens directly to the focus position along the value.

The above method has the advantages of being able to provide a good response to the user and having high accuracy because the best focus can be determined almost instantly. On the other hand, since a device (sensor) for distance measurement is required separately from the camera module, there are disadvantages such as an increase in cost and an increase in size. Therefore, it is often used in single-lens reflex cameras, which have a relatively large cost and size.

In addition to the above method, there is a contrast method as a method often used in compact digital cameras and the like. In the contrast method, images are sequentially captured while moving the focus position from the farthest end to the closest end, and the focus position where the contrast of the captured image is determined to be the highest is searched for. However, this method has a drawback that it takes time because it involves an operation of sequentially capturing images while moving the focus position.

Further, Patent Document 1 discloses a technique capable of preferably extracting an ID when an image of a barcode is taken to extract an ID. Specifically, when an image of a barcode is taken as a subject, an aiming frame for fitting the barcode is displayed on-screen on the display processing unit, and the barcode image acquired via the imaging unit is saved in the image buffer processing unit. Then, the ID is extracted from the saved barcode image and stored in the ID storage unit. An imaging condition setting unit is provided to set the imaging conditions corresponding to each of normal shooting and barcode shooting, and when barcode shooting is performed, the barcode image is fitted in the aiming frame, and the suitable imaging conditions are set to the barcode. Set as an imaging condition for shooting.

<p><patcit num="1"><text>Japanese Unexamined Patent Publication No. 2006-25055</text></patcit></p>

<p> However, the technique described in Patent Document 1 captures a barcode image by displaying an aiming frame for fitting a barcode on-screen and taking a picture with a composition in which the barcode is fitted in the aiming frame, and the image is captured. The ID is extracted from the barcode image. Therefore, it is inconvenient for the user to take a picture of the barcode according to the position and size of the aiming frame displayed on the liquid crystal display screen.</p><p> An object of the present invention is to provide a symbol reader and a program capable of extracting a symbol ID at high speed simply by inserting a symbol in the display screen of the symbol reader and taking a picture.</p>

<p> In order to solve the above problems, the symbol reading device of the invention according to claim 1 has an imaging means that captures a symbol to generate an image and a size of the symbol from the captured image generated by the imaging means. The size of the symbol is determined by comparing the size of the symbol detected by the detecting means with a preset value and determining the size of the symbol, and the result of the determination by the determining means. If it is smaller than the preset value, the focal position of the imaging means is moved to a predetermined position on the distant side, and if it is larger than the preset value, the focal position of the imaging means is moved to a predetermined position on the near side. It includes a focus movement control means for moving the symbol to, and an analysis means for analyzing symbol data corresponding to the symbol from the captured image generated by the imaging means.</p><p> The invention according to claim 2 has at least two different values in the preset values in the symbol reading device according to claim 1, and the focus movement control means is determined by the determination means. As a result, when the size of the barcode is smaller than the smaller of the two different values, the focal position of the imaging means is moved to a predetermined position on the distant side, and the two different values are used. If it is larger than the larger value, the focal position of the imaging means is moved to a predetermined position on the near side.</p><p> The invention according to claim 3 is the symbol reading device according to claim 1 or 2, wherein the symbol is a one-dimensional bar code or a two-dimensional code.</p><p> The invention according to claim 4 is the symbol reading device according to any one of claims 1 to 3, wherein the detecting means measures the size of the symbol based on a portion indicating a coordinate position included in the captured image. Detect.</p><p> The program of the invention according to claim 5 is an imaging means for capturing a symbol and generating an image, and a detecting means for detecting the size of the symbol from the captured image generated by the imaging function by using a computer of a symbol reading device. , A determination means for determining the size by comparing the size of the symbol detected by the detection function with a preset value, and as a result of the determination by the determination function, the size of the symbol is higher than the preset value. Focus movement control that moves the focal position of the imaging function to a predetermined position on the distant side when is small, and moves the focal position of the imaging function to a predetermined position on the near side when the value is larger than a preset value. It functions as a means, an analysis means for analyzing symbol data corresponding to the symbol from the captured image generated by the imaging function.</p>

<p> According to the present invention, it is possible to provide a symbol reader and a program capable of extracting a symbol ID at high speed simply by inserting a symbol in the display screen of the symbol reader and taking a picture.</p>

<figref num="1">It is a block diagram which shows the schematic structure of the symbol reading apparatus 1 which concerns on this embodiment.</figref><figref num="2">It is a figure which showed the state of the focus adjustment when trying to take a two-dimensional code.</figref><figref num="3">It is a figure which showed the relationship between the distance from the image pickup unit 10 of the symbol reading apparatus 1 to the 2D code which is a subject, and the lens position of a focus lens 11b.</figref><figref num="4">It is a flowchart which showed an example of the two-dimensional code reading process performed in the symbol reading apparatus 1 which concerns on this embodiment.</figref><figref num="5">It is a flowchart which showed an example of the symbol area calculation process.</figref><figref num="6">It is a figure which showed each scene in the symbol area calculation process.</figref><figref num="7">It is a flowchart which showed an example (two-dimensional code reading process 2) of the two-dimensional code reading process performed in the symbol reading apparatus 1 which concerns on this embodiment.</figref><figref num="8">It is a flowchart which showed an example (two-dimensional code reading process 2) of the two-dimensional code reading process performed in the symbol reading apparatus 1 which concerns on this embodiment.</figref>

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of the symbol reading device 1 according to the present embodiment. As shown in FIG. 1, the symbol reading device 1 includes an imaging unit 10, a data processing unit 20, a user interface unit 30, and an acceleration sensor 40.

The image pickup unit 10 includes an image pickup lens unit 11, a lens drive unit 12, and an image sensor 13, and has a function of photographing a subject. The image pickup lens unit 11 is composed of, for example, a plurality of lenses that collect light for photographing a subject, and includes a zoom lens 11a for adjusting the magnification, a focus lens 11b for adjusting the focus, and the like. The lens drive unit 12 includes a zoom lens drive unit 12a that moves the zoom lens 11a in the optical axis direction, a focus lens drive unit 12b that moves the focus lens 11b in the optical axis direction, and the like when imaging a subject. The zoom lens drive unit 12a and the focus lens drive unit 12b each include an encoder and can detect the amount of rotation of each motor. The image sensor 13 is, for example, a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide). It is composed of a solid-state image sensor such as Semiconductor), and the image formed by the image pickup lens unit 11 condensing light is captured as digitized image data. The captured image data is temporarily stored in the memory 21 of the data processing unit 20.

The data processing unit 20 includes a memory 21, an image processing unit 22, an image output unit 23, a control unit 24, and a program memory 25. The memory 21 temporarily stores image data (for example, a bar code image) captured by the image sensor 13 each time a shooting process is performed. The memory 21 also stores image data required for image processing, values of various flags, threshold values, and the like. Further, the memory 21 includes a display memory area for storing and reading display image data for displaying an image. The image processing unit 22 performs predetermined image processing for displaying an image on the image data temporarily stored in the memory 21. The image data subjected to the image processing is stored in the display memory area of the memory 21 as display image data. The image output unit 23 reads the display image data stored in the display memory area of the memory 21, generates an RGB signal based on the read display image data, and uses the generated RGB signal as the user interface unit 30. Output to the liquid crystal display unit 31 of. Further, by outputting the RGB signal to the outside via the external interface 33 of the user interface unit 30, it is possible to display an image on an external device such as a television, a PC, or a projector.

The control unit 24 includes a CPU and RAM (not shown), a zoom lens drive control unit 24a, a focus lens drive control unit 24b, and a blur correction processing unit 24c, and is used for the symbol reader 1 stored in the program memory 25. Various control operations are performed according to the program of. The zoom lens drive control unit 24a calculates and holds in advance the number of pulses (drive amount) required for driving the zoom lens 11a by the DC motor, and controls the drive of the zoom lens 11a based on the drive amount. The focus lens drive control unit 24b controls the position of the focus lens 11b according to the evaluation value of the focus accuracy of the image imaged by the image pickup lens unit 11, for example, the contrast value and the edge amount. Further, the focus lens drive control unit 24b calculates the focus tracking position based on the calculated driving amount, and drives the focus lens 11b to the focus tracking position. The blur correction processing unit 24c drives a blur correction lens (not shown) of the image pickup lens unit 11 in a direction orthogonal to the optical axis according to the amount of blur of the symbol reading device 1 input from the acceleration sensor 40 described later, and is an image sensor. Control is performed to correct the blurring of the image formed on 13.

Further, the control unit 24 detects the size of the two-dimensional code from the captured image generated by the imaging unit 10, compares the size of the detected two-dimensional code with a preset value, and determines the size. .. As a result of the determination, if the size of the two-dimensional code is smaller than the preset value, the focus position of the focus lens 11b is moved to a predetermined position on the distant side, and if it is larger than the preset value, the focus is set. The focal position of the lens 11b is moved to a predetermined position on the near side. Then, the symbol data corresponding to the two-dimensional code is analyzed from the generated captured image.

The program memory 25 is composed of a storage device such as a ROM (Read Only Memory) or a flash memory, and stores various programs and data necessary for the operation of the control unit 24. Specifically, it stores a two-dimensional code reading program or the like for analyzing a two-dimensional code and acquiring information.

The user interface unit 30 includes a liquid crystal display unit 31, an operation unit 32, an external interface 33, and an external memory 34. The liquid crystal display unit 31 displays the subject image based on the RGB signal output from the image output unit 23. Specifically, a live view image based on a plurality of image data generated by the imaging unit 10, a moving image recorded in the external memory 34 during recording, or a moving image recorded in the external memory 34 can be displayed. Is played back and displayed. The liquid crystal display unit 31 may be provided with an image memory (not shown) for temporarily storing display image data appropriately output from the image output unit 23. The operation unit 32 is a function for the user to perform a predetermined operation on the symbol reading device 1, and outputs an operation signal corresponding to the user's operation to the control unit 24. The operation unit 32 includes, for example, a shutter button, a selection determination button, a playback button, a shooting button, a mode switching button, and the like. The mode switching button is a button used when switching between a moving image shooting mode for shooting a moving image and a still image shooting mode for shooting a still image. The external interface 33 is a terminal for connecting to an external device such as a television, a PC, or a projector, and transmits / receives data via a predetermined communication cable. The external memory 34 is composed of, for example, a card-type non-volatile memory (flash memory), a hard disk, or the like, and has a plurality of image data of a subject image captured by the imaging unit 10 and compressed and encoded by the image processing unit 22. Remember.

The acceleration sensor 40 physically and directly detects the movement of the symbol reading device 1, and inputs a measured value indicating the angular velocity to the control unit 24.

The ID management unit 50 includes an ID extraction unit 51 and an ID storage unit 52. The ID extraction unit 51 extracts an ID from the barcode image stored in the memory 21 based on a command from the control unit 24. The extracted ID is stored in the ID storage unit 52. Hereinafter, the operation of the digital camera 1 will be described with reference to FIGS. 2 to 8.

FIG. 2 is a diagram showing a state of focus adjustment when trying to shoot a two-dimensional code. A two-dimensional code is a display-type code that has information in the horizontal and vertical directions, such as a QR code. Hereinafter, the captured image of the two-dimensional code is referred to as a symbol image. It is assumed that the focus lens 11b is in the default position (F0) when the symbol image is taken.

FIG. 2 (a) shows a live view image when the symbol image is taken from a distance. In the present embodiment, "far" is defined as a distance of 15 cm from the image pickup unit 10 of the symbol reader 1. When shooting is performed from a far position, as shown in FIG. 2A, a small symbol image is displayed on the screen of the liquid crystal display unit 31 in an out-of-focus state. Fig. 2 (b) shows how the focus lens 11b was moved to the far side (F +) in order to eliminate this out-of-focus.

FIG. 2 (c) shows a live view image when an attempt is made to take a symbol image in a focused state. In the present embodiment, when the focus lens 11b is in the default position (F0), the distance (= focus position) that naturally comes into focus is 10 cm from the image pickup unit 10 of the symbol reader 1. When shooting is performed in the in-focus state, the in-focus symbol image is displayed on the screen of the liquid crystal display unit 31 as shown in FIG. 2 (d).

FIG. 2 (e) shows a live view image when an attempt is made to take a symbol image from a close distance. In this embodiment, "proximity" is defined as a distance of 5 cm from the image pickup unit 10 of the symbol reader 1. When shooting is performed from "proximity", as shown in FIG. 2 (e), a large symbol image is displayed on the screen of the liquid crystal display unit 31 in an out-of-focus state. FIG. 2 (f) shows how the focus lens 11b is moved to the near side (F-) in order to eliminate this out-of-focus.

As described above, the symbol reading device 1 according to the present embodiment determines the focus state by determining the approximate size of the symbol image, and moves the position of the focus lens 11b back and forth.

FIG. 3 is a diagram showing the relationship between the distance from the image pickup unit 10 of the symbol reader 1 to the two-dimensional code that is the subject and the lens position of the focus lens 11b. For example, when the distance from the image pickup unit 10 of the symbol reader 1 to the two-dimensional code is short, the focus is on the region where the symbol image is captured in a larger size. That is, reading is successful when the focus lens 11b is on the near side (F-). Further, when the distance from the image pickup unit 10 of the symbol reader 1 to the two-dimensional code is near the focus position, it is possible to focus without moving the focus lens 11b from the default position (F0). In the present embodiment, a little out-of-focus can be tolerated by performing the image analysis process. Therefore, decoding can be successful in a relatively wide range. Further, when the distance from the image pickup unit 10 of the symbol reader 1 to the two-dimensional code is long, the symbol image is focused in a smaller imaged region. That is, reading is successful when the focus lens 11b is on the far side (F +).

(First Embodiment) FIG. 4 is a flowchart showing an example of a two-dimensional code reading process performed in the symbol reading device 1 according to the present embodiment. This two-dimensional code reading process is realized by the control unit 24 executing the two-dimensional code reading program stored in the program memory 25.

As shown in FIG. 4, in step S101, the position of the focus lens 11b is moved to the default position (F0). In step S102, the symbol image captured by the imaging unit 10 is displayed through the liquid crystal display unit 31. In step S103, it is determined whether or not the shooting button of the operation unit 32 is pressed by the user. If the shooting button is pressed, the process proceeds to the next step S104, and if the shooting button is not pressed, the process proceeds to step S102. In step S104, the symbol area calculation process is performed. This symbol area calculation process will be specifically described with reference to FIGS. 5 and 6.

FIG. 5 is a flowchart showing an example of the symbol area calculation process. Further, FIG. 6 is a diagram showing each scene during the symbol area calculation process. As shown in FIG. 5, in step S201, the original image (see FIG. 6 (a)) displayed through in step S102 of FIG. 4 is binarized (see FIG. 6 (b)). In step S202, the original image binarized in step S201 is divided into blocks (see FIG. 6 (c)). For example, a QVGA (320x240) image is divided into 40x30 blocks in 8-pixel units. The appropriate pixel unit shall be set in advance by an evaluation experiment. In step S203, each block divided in step S202 is divided into a black block and a white block. The set value for determining the black block is calculated in advance by an evaluation experiment. However, it can be changed later according to the actual environment. In step S204, a block of black blocks near the center of the original image is searched for. Specifically, the lump block is extracted by subjecting the original image to a labeling process. In step S205, the total number of blocks occupied by the black block block is counted.

Next, in step S105 of FIG. 4, it is determined whether or not the size is smaller than the set value 1. The set value 1 is the value b shown in FIG. 3, that is, the boundary point between the range that can be imaged at the default position (F0) and the range that can be imaged at the distant side (F +). If the size is smaller than the set value 1, the process proceeds to the next step S106, and if the size is greater than or equal to the set value 1, the process proceeds to step S107. In step S106, the focus lens 11b is moved to the far side (F +). In step S107, it is determined whether or not the size is larger than the set value 2. The set value 2 is the value of a shown in FIG. 3, that is, the boundary point between the range that can be imaged at the default position (F0) and the range that can be imaged at the near side (F-). If the size is larger than the set value 2, the process proceeds to the next step S108, and if the size is smaller than the set value 2, the process proceeds to step S109. In step S108, the focus lens 11b is moved to the near side (F-).

In step S109, the image pickup unit 10 captures a still image with high-resolution VGA. In step S110, the still image captured in step S109 is analyzed and decoding processing is performed. In step S111, it is determined whether or not the decoding of the still image is successful. If the decoding is successful, the two-dimensional code reading process is terminated, and if the decoding is not successful, the process proceeds to the next step S112. In step S112, it is determined whether or not the number of retries of the decoding process has been exceeded. The number of retries can be arbitrarily set by the user. If the number of retries is exceeded, the process proceeds to the next step S113, and if the number of retries is not exceeded, the process proceeds to step S109. In step S113, a message indicating the decoding failure is displayed on the liquid crystal display unit 31. When the message is displayed, the two-dimensional code reading process is terminated.

As described above, in the first embodiment, the approximate size (area occupied in the captured image) of the two-dimensional code is determined from the captured image, and the size is smaller than the preset value. If it is small, the position of the focus lens 11b is moved to a predetermined position on the distant side, and if it is larger than the larger value among the preset values, the position of the focus lens 11b is moved to a predetermined position on the near side. If this is not the case, the shooting operation is executed again with the position of the focus lens 11b as it is, and the image is analyzed and the decoding process is performed.

That is, instead of moving the focus adjustment mechanism step by step to judge the image one by one (repeating the cycle of "image capture-&gt; image judgment-&gt; focus movement" multiple times) to move to a more desirable focus position. Since it moves to a preset predetermined position at once, no extra capture time or image determination time is required during that time. In addition, the power consumption required for that purpose becomes unnecessary. Therefore, both good response and reduction of power consumption can be realized. In particular, it is highly effective for camera modules such as liquid lenses, where the focus movement is overwhelmingly faster than the capture time of one screen.

(Second Embodiment) 7 and 8 are flowcharts showing an example (two-dimensional code reading process 2) of the two-dimensional code reading process performed in the symbol reading device 1 according to the present embodiment. As shown in FIG. 7, in step S301, the position of the focus lens 11b is moved to the default position (F0). In step S302, the symbol image captured by the imaging unit 10 is displayed through the liquid crystal display unit 31. In step S303, it is determined whether or not the shooting button of the operation unit 32 is pressed by the user. If the shooting button is pressed, the process proceeds to the next step S304, and if the shooting button is not pressed, the process proceeds to step S302.

In step S304, the image pickup unit 10 captures a still image with high-resolution VGA. In step S305, the still image captured in step S304 is analyzed and decoding processing is performed. In step S306, it is determined whether or not the decoding of the still image is successful. If the decoding is successful, the two-dimensional code reading process is terminated, and if the decoding is not successful, the process proceeds to the next step S307. In step S307, it is determined whether or not the number of retries of the decoding process has been exceeded. The number of retries can be arbitrarily set by the user. If the number of retries is exceeded, the process proceeds to the next step S308, and if the number of retries is not exceeded, the process proceeds to step S309. In step S308, a message indicating the decoding failure is displayed on the liquid crystal display unit 31. When the message is displayed, the two-dimensional code reading process is terminated.

In step S309, it is determined whether or not the symbol size can be estimated. The symbol size is the size of the symbol image, and the estimation of the symbol size is performed based on the portion indicating the coordinate position included in the captured image (the centerpiece portion of the two-dimensional code). If the symbol size can be estimated, the process proceeds to step S315 in FIG. 8, and if the symbol size cannot be estimated, the process proceeds to the next step S310. In step S310, the symbol area calculation process is performed. Since this symbol area calculation process has been specifically described with reference to FIGS. 5 and 6, the description thereof will be omitted here. In step S311 it is determined whether the size is smaller than the set value 1. The set value 1 is the value b shown in FIG. 3, that is, the boundary point between the range that can be imaged at the default position (F0) and the range that can be imaged at the distant side (F +). If the size is smaller than the set value 1, the process proceeds to the next step S312, and if the size is greater than or equal to the set value 1, the process proceeds to step S313. In step S312, the focus lens 11b is moved to the far side (F +). In step S313, it is determined whether or not the size is larger than the set value 2. The set value 2 is the value of a shown in FIG. 3, that is, the boundary point between the range that can be imaged at the default position (F0) and the range that can be imaged at the near side (F-). If the size is larger than the set value 2, the process proceeds to the next step S314, and if the size is smaller than the set value 2, the process proceeds to step S304. In step S314, the focus lens 11b is moved to the near side (F-).

Next, in step S315 of FIG. 6, it is determined whether or not the estimated size (calculated from the distance between the portions indicating the coordinate positions) is smaller than the set value 3. The set value 3 is the value b shown in FIG. 3, that is, the boundary point between the range that can be imaged at the default position (F0) and the range that can be imaged at the distant side (F +). If the estimated size is smaller than the set value 3, the process proceeds to the next step S316, and if the estimated size is 3 or more, the process proceeds to step S317. In step S316, the focus lens 11b is moved to the far side (F +). In step S317, it is determined whether or not the estimated size is larger than the set value 4. The set value 4 is the value of a shown in FIG. 3, that is, the boundary point between the range that can be imaged at the default position (F0) and the range that can be imaged at the near side (F-). If the estimated size is larger than the set value 4, the process proceeds to the next step S318, and if the estimated size is less than the set value 4, the process proceeds to step S304.

In this way, in the second embodiment, it is determined whether or not the symbol size can be estimated based on the eyeball portion (the portion indicating the coordinate position) of the two-dimensional code, and when the symbol size can be estimated. , The position of the focus lens 11b is adjusted based on the symbol size, the image is analyzed, and the decoding process is performed. As a result, even if the decoding of the two-dimensional code fails, the image can be analyzed and the decoding process can be performed as long as the symbol size can be estimated without taking a picture of the two-dimensional code again. , It is possible to omit unnecessary shooting operations.

Although the specific description has been given above based on the embodiment of the present invention, the present invention is not limited to the above embodiment and can be changed without departing from the gist thereof.

For example, in the above embodiment, the process when the two-dimensional code is imaged as a symbol is described, but the same process can be used when the one-dimensional bar code is imaged.

Further, in the above embodiment, "far" is defined as a distance of 15 cm from the imaging unit 10, "focus position" is defined as a distance of 10 to 10 cm from the imaging unit, and "proximity" is defined as a distance of 10 to 5 cm from the imaging unit. Not limited to this, it can be set in any way according to the specifications of the imaging unit 10.

Further, in the above embodiment, two different values are used for the set value used when determining the approximate size of the symbol, but the set value may be one. When there is one set value, if the symbol size is smaller than the set value, the focus position of the focus lens 11b is moved to a predetermined position on the distant side, and if it is larger than the set value, the focus position of the focus lens 11b is moved. Will be moved to a predetermined position on the proximity side.

In addition, the detailed configuration and detailed operation of each device constituting the symbol reading device 1 can be appropriately changed without departing from the spirit of the present invention.

1 Symbol reader 10 Imaging unit 11 Imaging lens section 11a zoom lens 11b focus lens 12 Lens drive unit 12a Zoom lens drive 12b Focus lens drive unit 13 Image sensor 20 Data processing unit 21 memory 22 Image processing unit 23 Image output section 24 Control unit 24a Zoom lens drive control unit 24b Focus lens drive control unit 24c Blur correction processing unit 25 program memory 30 User interface section 31 Liquid crystal display 32 Operation unit 33 External interface 34 External memory 40 accelerometer 50 ID discriminator 51 ID extraction unit 52 ID storage