Combination touch and transducer input system and method

0001The present invention relates generally to user interfaces for electronic devices, and more specifically to input systems and controllers using touch sensors and digitizer systems.

0002Diverse and different types of input devices include diverse and different electronic systems, including computers (eg laptop computers, tablet computers, personal digital computers) and communication devices (eg mobile phones, wireless handheld communication devices). Is commonly used in. Certain types of input devices are commonly referred to as touch sensors or proximity sensors. Touch sensors use a variety of different techniques to determine the position of nearby objects such as fingers. For example, a capacitive touch sensor determines the position of a proximity object by determining a capacitance change caused by the presence of the proximity object. Another type of input device is commonly referred to as a digitizer tablet, but is also referred to as a graphics tablet, graphics pad, or drawing tablet. The digitizer tablet has a detection surface that can be input by the user using a position indicator, which is typically implemented as a stylus or other pen-like drawing device. In a general digitizer, the position indicator emits an electromagnetic signal detected by the detection surface. The electromagnetic signal detected by the detection surface is then used and processed to determine the position of the position indicator.

0003In general, a digitizer is superior in position detection accuracy and resolution as compared with a general touch sensor. Digitizers usually require a dedicated position indicator for input. It has been desired to combine the attributes of the touch sensor (eg, convenience) with the improved accuracy and resolution of the digitizer. Unfortunately, the combinatorial touch sensor digitizer supports the cost and complexity associated with realization, the additional 3D space required to accept this combination, and touch detection and position indicator detection. Its applicability was limited due to the requirements for the special type of display to be obtained. For this reason, input devices that use improved combination touch sensors and position indicators continue to be needed.

0004Note that Patent Document 1 includes a tablet in which a plurality of X electrodes and Y electrodes arranged at equal pitch intervals are stacked in a matrix, and an input pen that transmits a voltage of a predetermined frequency. A coordinate input device for detecting a voltage applied to each electrode based on a change in capacitance between electrodes is disclosed.

<p num="0005"><patcit num="1"><text>Japanese Unexamined Patent Publication No. 8-147092</text></patcit></p>

<p num="0006"> In the present invention, the object (finger) and the position indicator (active electrostatic pen) can be substantially detected by time-division processing using the same electrode array (normal XY electrode sensor). To do. Then, when the position indicator is detected, a large amount of processing time is allocated for signal processing for the position indicator. In the present invention, the "sensor" refers to the entire receiving device. Further, the signal from the position indicator is repeatedly measured, and the signal processing on the receiving side, that is, the signal processing synchronized with the pen signal is performed with reference to the signal from the position indicator. Therefore, the first object of the present invention is to secure the desired position detection performance for the electrostatic pen even when the finger and the active electrostatic pen can be detected substantially simultaneously using the same electrode array. To be able to do it. A second object of the present invention is to make it possible to efficiently perform signal processing (demodulation processing) on the sensor side by synchronizing with an electric field asynchronously emitted from an electrostatic pen.</p>

<p num="0007"> In order to solve the above problems, the input system of the present invention has a position indicator having a pen shape and radiating an electric field, a plurality of electrodes arranged in the first direction, and a second direction different from the first direction. It has an electrode array having a plurality of electrodes arranged in the direction of the above, and a sensor having a controller coupled to the electrode array and controlling to detect a position indicator and an object on the electrode array. The position indicator used in the input system of the present invention includes a pressure sensor that detects the pressure applied to the tip thereof, and also includes a transmitting means that transmits the pressure detected by the pressure sensor to the sensor. Further, the controller used in the input system of the present invention is an electrode array based on the attributes obtained by measuring the signals induced in the electrodes arranged in at least one of the first direction and the second direction. Electrodes based on touch mode operation that detects the above object by capacitive coupling and the attributes obtained by measuring the signals induced in the electrodes arranged in each of the first and second directions. The position indicator mode operation that detects the position indicator on the array is controlled to be switched alternately. As a result, the object and the position indicator can be separated.<u style="single">Alternately</u>As well as being detectable<u style="single">In the position indicator mode operation switched by the control that switches between the touch mode operation and the position indicator mode operation alternately</u>When the position indicator is detected, the control for continuing the position indicator mode operation for a predetermined time is performed.</p><p num="0008"> Further, in a preferred embodiment of the present invention, when transmitting from the position indicator to the sensor via the transmitting means, a frame start block indicating the start of the frame and a data block including a digital value corresponding to the pressure detected by the pressure sensor are included. It is provided with a data frame format having the above, and is modulated by a predetermined transmission method. Here, the modulation in the predetermined transmission method is preferably ASK modulation.</p><p num="0009"> Further, in the position indicator mode operation, the above controller has a predetermined transmission method based on the attributes obtained by repeatedly measuring the signals induced in the electrodes constituting the electrode array by the electric field radiated from the position indicator. Performs demodulation processing of the signal modulated by. As a result, the demodulation process synchronized with the electric field radiated asynchronously from the position indicator can be performed on the sensor. Further, the controller can also control to start the measurement for a new data frame when the repeated measurement of the signal induced in the electrodes constituting the electrode array elapses for a predetermined time.</p><p num="0010"> Further, in the input system of the present invention, the data frame format is further provided with a data format block indicating the data format, and the data format block indicates that the data transmitted to the sensor via the transmission means is pressure. I try to instruct by.</p><p num="0011"> Further, in the preferred embodiment of the present invention, the controller used in the input system corresponds to the supply of the drive signal to the electrodes arranged in one of the first direction and the second direction in the touch mode operation. Then, the signal induced in the electrode arranged in the other direction of the first direction and the second direction is measured, and the object on the electrode array is detected based on the obtained attribute. .. Then, in a preferred embodiment of the present invention, the position indicated by at least one of the object and the position indicator on the electrode array is determined based on the attribute obtained by measuring the signal induced in the electrodes constituting the electrode array. It is provided with a positioning means for determining the position. It is preferable that the transmitting means is provided at the pen tip portion of the position indicator and transmits a signal to the sensor. In this case, the signal transmitted from the transmitting means is received by the electrode array provided in the sensor.</p><p num="0012"> Further, the controller of the present invention is coupled to an electrode array having a plurality of electrodes arranged in the first direction and a plurality of electrodes arranged in a second direction different from the first direction, and is mounted on the electrode array. It is a position indicator that radiates an electric field and a controller that controls to detect an object. This controller capacitively couples an object on an electrode array based on attributes obtained by measuring signals induced in electrodes arranged in at least one of the first direction and the second direction. Based on the touch mode operation detected by the camera and the attributes obtained by measuring the signals induced in the electrodes arranged in each of the first and second directions, the position indicator on the electrode array is set. Control to switch the position indicator mode operation to be detected alternately. As a result, the object and the position indicator can be separated.<u style="single">Alternately</u>As well as being detectable<u style="single">In the position indicator mode operation switched by the control that switches between the touch mode operation and the position indicator mode operation alternately</u>When the position indicator is detected, the control for continuing the position indicator mode operation for a predetermined time is performed.</p><p num="0013"> In a preferred embodiment of the controller of the present invention, the electric field radiated from the position indicator is modulated by a predetermined transmission method, and the controller sets the electrode array by the electric field radiated from the position indicator in the position indicator mode operation. The demodulation process of the signal modulated by a predetermined transmission method is executed based on the attribute obtained by repeatedly measuring the signal induced in the constituent electrodes. As a result, the sensor is demodulated in synchronization with the electric field radiated asynchronously from the position indicator.</p><p num="0014"> The electric field radiated from the position indicator has a frame start block indicating the start of the frame and a data frame format having a data block, and the controller determines repeated measurement of signals induced in the electrodes constituting the electrode array. When time has passed, it is preferable to control the start of measurement for a new data frame. Further, in the touch mode operation, the controller corresponds to the supply of the drive signal to the electrodes arranged in one of the first direction and the second direction, and the controller has the first direction and the second direction. The object on the electrode array is detected based on the attribute obtained by measuring the signal induced in the electrodes arranged in the other direction of the above. Further, in a preferred embodiment of the controller of the present invention, the position indicated on the electrode array by at least one of the object and the position indicator based on the attribute obtained by measuring the signal induced in the electrodes constituting the electrode array. It is equipped with a position-determining means for determining.</p><p num="0015"> The present invention can be more easily understood by referring to the accompanying drawings.</p>

0016<figref num="1">FIG. 5 is a schematic representation of a tablet computer provided with a combinatorial touch and transducer input system according to an embodiment of the present invention.</figref><figref num="2">FIG. 5 is a schematic representation of a sensor with a control device and an electrode array used in a combinatorial touch and transducer input system according to an embodiment of the present invention.</figref><figref num="3">3 (a) and 3 (b) are schematic views of a converter used in a combinatorial touch and transducer input system according to an embodiment of the present invention.</figref><figref num="4">It is a block diagram of the converter according to the Example of this invention.</figref><figref num="5">FIG. 5 (a) is a block diagram of a sensor provided with a control device and an electrode array according to an embodiment of the present invention. FIG. 5B is a schematic representation of an electrode array according to an embodiment of the present invention, divided into one or more touch mode regions and one or more transducer mode regions.</figref><figref num="6">FIG. 5 is a block diagram of a processing stage according to an embodiment of the present invention, which constitutes the control device of FIG. 5 (a).</figref><figref num="7">It is a circuit diagram of the charge amplifier according to the embodiment of this invention which constitutes the processing stage of FIG.</figref><figref num="8">It is a circuit diagram of the voltage amplifier according to the embodiment of this invention which constitutes the processing stage of FIG.</figref><figref num="9">It is a circuit diagram of the transimpedance amplifier according to the embodiment of this invention which constitutes the processing stage of FIG.</figref><figref num="10">It is a circuit diagram of the continuous type transimpedance amplifier according to one Embodiment of this invention which constitutes the processing stage of FIG.</figref><figref num="11">FIG. 11 (a) is a flowchart illustrating a step of scanning the electrode array in the converter mode according to an embodiment of the present invention. 11 (b) and 11 (c) are schematic views for showing the connection status of the electrodes according to an embodiment of the present invention. FIG. 11D is a schematic diagram showing the detection of a signal induced in an electrode according to an embodiment of the present invention.</figref><figref num="12">It is a schematic diagram of the digital filtering procedure according to one Example of this invention.</figref><figref num="13">FIG. 13 (a) is a flowchart in the case of using the curve fitting technique according to an embodiment of the present invention, and FIG. 13 (b) is a graph of a sample parameterized curve according to an embodiment of the present invention. c) is a schematic diagram of a phase-locked loop (PLL) circuit used in one embodiment of the present invention.</figref><figref num="14">FIG. 5 is a schematic diagram of a sample data frame for digital data transmission in a combinatorial touch and transducer input system according to an embodiment of the present invention.</figref><figref num="15">It is a flowchart which illustrates the process performed by the converter by one Example of this invention.</figref><figref num="16">Is a flowchart illustrating a step of decoding digital data encoded by frequency shift according to an embodiment of the present invention.</figref>

0017Each embodiment of the present invention provides a system and method that facilitates user input into an electronic system. A combinatorial touch and transducer input system is provided that facilitates user input using conventional objects (eg, fingers) and transducers (eg, styluses) that generate an electric field for position detection.

0018FIG. 1 illustrates a tablet computer 100 suitable for incorporating a combinatorial touch and transducer input system according to an embodiment of the present invention. This tablet computer includes a display 102 such as an LCD device, which is usually provided with a transparent detection surface 104 over the entire surface. The detection surface 104 is used to detect a normal object (eg, finger 106) as well as to detect one or more transducers (eg, stylus 108). And can form part of the converter input system. Specifically, an electrode array configured to detect the position of the converter by capacitively detecting nearby objects in the same way as receiving the electric field generated by the converter (not shown in FIG. 1). ) Is inside the detection surface 104 or below the detection surface 104.

0019According to various exemplary embodiments of the invention, the combinatorial touch and transducer input system is in touch detection mode (or "touch mode" for short) and converter detection mode (or "transducer mode" for short). It operates and is configured to operate substantially simultaneously or alternately by switching between the two modes in a continuous sampling cycle. In touch mode, the system is configured to locate a nearby object by capacitively detecting it using an electrode array. In transducer mode, the system is configured to position the transducer by measuring the attributes (eg, amplitude, phase, etc.) of multiple signals induced in the electrode array by the electric field generated by the transducer. Will be done. The same electrode array is used for both touch detection and transducer detection. Therefore, the user can interface with the tablet computer 100 using a normal object (eg, finger 106, etc.) or a converter (eg, stylus 108, etc.). During operation, the user uses the finger 106 and / or the stylus 108 and the sensing surface 104 to perform various user interface functions such as launching icons, moving cursors, and entering text and other data. can do.

0020Although the illustrated embodiment shows the tablet computer 100, each embodiment of the present invention can be applied to any type of device that utilizes an input device. Each example includes other computing devices, media devices, and communication devices. Further, although the illustrated embodiment shows finger 106, a sensor that operates in touch mode with any other capacitive object (having sufficient dimensions to form a mutual capacitance with at least one electrode). Can be used to interface with. Finally, the illustrated embodiment shows the stylus 108, but any other, including other pen-like devices, pointers, cursors, pucks, mice, pawns, and other tools. Appropriate converters can be used.

0021Combined touch and transducer input systems typically consist of a transducer (eg, stylus 108 in FIG. 1) and a sensor 150 shown in FIG. The sensor 150 includes a sensor control device 152 and an electrode array 154. In the illustrated embodiment, the electrode array 154 is an elongated electrode 154a that constitutes a first set extending in a first direction (eg, horizontally), and a different (eg, orthogonal) first direction. It comprises elongated electrodes 154b that make up a second set that extends in two directions (eg, vertical). A sheet of dielectric material (eg, glass (not shown)) or other geometry is interposed between the elongated electrodes 154a and 154b that make up the first and second pairs. Further, by covering the electrode array 154 with a sheet of another material such as glass (not shown in FIG. 2), the electrode array 154 is electrically insulated and separated and physically protected, as shown in FIG. It functions collectively as a detection surface 104.

0022Generally, the electrode array 154 is formed by adhering a transparent conductive material to one or more sheets. For example, conductors such as indium tin oxide (ITO) can be patterned on one or both sides of the glass sheet to form elongated electrodes 154a and 154b, which make up the first and second pairs, respectively. At this time, another glass sheet may be arranged to form the detection surface 104. Various different electrode shapes (eg, diamond-shaped electrodes and square-shaped electrodes) may be used as in the array pattern, and the electrode array 154 used in the present invention is not limited to the specific shape shown in FIG. Absent. For example, FIG. 2 shows an electrode array 154 formed by using rectangular electrodes in which two layers are overlapped. For example, the electrodes forming the first and second pairs having a diamond pattern shape are simple. An electrode arrangement configuration in which the electrodes are arranged on one layer so as not to substantially overlap each other is also effective. In various other embodiments, the electrodes that make up the first and second pairs are substantially orthogonal to each other and simply extend in two different directions. In each of the other embodiments, the electrodes of each set need not be substantially parallel to each other. Furthermore, the array pattern may include not only the electrodes that make up the first and second pairs, but also the properly arranged third, fourth and additional pairs of electrodes.

0023The control device 152 of the sensor 150 is configured to perform signal processing for position fixing in this combinatorial touch and transducer input system. This will be described in detail with reference to FIG. 5 (a). The sensor control device 152 preferably includes any type of processing device, including an integrated circuit such as a microprocessor. Further, the sensor control device 152 may include a large number of individual devices, including an arbitrary appropriate number of integrated circuit devices and / or circuit boards that operate in cooperation with each other. For example, the sensor control device 152 may include devices such as a microcontroller, processor, multiplexer, filter, amplifier, and interface. Finally, in some applications, the sensor controller 152 is configured to execute each program embedded in memory.

0024When operating in touch mode, the sensor controller 152 is configured to determine the position of each object by capacitively detecting each of one or more nearby objects using the electrode array 154. Various techniques for capacitive touch detection are known, including a multi-touch detection technique (multi-touch technique) capable of detecting a large number of touches at one time. For example, when the sensor control device 152 continuously drives a signal for each of the elongated electrodes 154a constituting the first set of the electrode array 154 as shown in FIG. 2, the elongated electrodes constituting the first set Each intersection of the 154a and the elongated electrodes 154b that make up the second set form a capacitor. More generally, a first that overlaps or does not overlap with at least one electrode of the elongated electrodes 154a that make up the first set and at least one of the elongated electrodes 154a that make up this first set. A capacitor is formed with a pair of electrodes composed of at least one electrode constituting two sets of elongated electrodes 154b. When an object such as a finger is placed on or in close proximity to one of these capacitors, a portion of the lines of electric field generated from the capacitor is drawn towards the finger, causing a reduction in the capacitance of the capacitor. These capacitance changes are reflected in the signal output from one of the elongated electrodes 154b that make up the second set of capacitors. Thereby, the control device 152 can determine the position of the proximity object. Further, based on this determined position, one elongated electrode of the elongated electrodes 154a constituting the first set receives a drive signal (for example, Y coordinate), and the elongated electrode constituting the second pair is formed. One of the 154b elongated electrodes outputs a signal indicating a capacitance change (eg, X coordinate). Further, this is an example of the capacitive touch detection technique, and various other capacitive touch detection techniques can be used in the touch mode operation of the present invention.

0025FIG. 3 (a) is a simplified block diagram of the transducer 175 used in the combinatorial touch and transducer input system according to an embodiment of the present invention. The converter 175 includes a converter control device 177 and an antenna 179. FIG. 3 (b) is a partial cross-sectional view of the converter 175 embodied as a stylus according to an embodiment of the present invention. The stylus transducer 175 includes a generally cylindrical elongated body 330 accommodating a converter controller 177 (see FIG. 4) and an antenna 179 embodied as the pen tip of the stylus converter 175. The transducer shown in FIG. 3 (b) is suitable for use in electrically (ie, capacitively) coupling the antenna 179 and the electrode array 154 using the electric field generated by the transducer 175. The following description relates to an embodiment in which the transducer and sensor are electrically (ie, capacitively) coupled. However, in another embodiment of the invention, the transducer and sensor are magnetically coupled using the magnetic field component of the electromagnetic field generated by the transducer, as will be described later with reference to FIG. 11 (d). You may.

0026The converter control device 177 controls the operation of the converter 175, and is appropriately provided with any type of processing device including an integrated circuit such as a microprocessor, as described below with reference to FIG. good. Also, the transducer control device 177 may include a number of individual devices, including any suitable number of integrated circuit devices and / or circuit boards that operate in concert. For example, the converter controller 177 may include devices such as pressure sensors, switches, capacitors, regulators, microcontrollers, and processors.

0027The transducer controller 177 regulates the radiation of the electric field from the antenna 179. When the transducer 175 is in close proximity to the electrode array 154, the electric field radiated by the antenna 179 will induce a detection signal on one or more electrodes. Specifically, by applying a voltage V to the converter antenna 179, the converter antenna 179 as one end (upper plate) constituting the counter electrode of the capacitor and the other end (bottom plate) constituting the counter electrode of this capacitor. The amount of charge Q is accumulated in one or more of the electrodes of the electrode array 154. Also, an electric field is formed between the antenna 179 and one or more of the electrodes of the electrode array 154. This electric field induces opposite charges on one or more of the electrodes in the electrode array 154. In this case, the amount of charge induced is proportional to the capacitance between the transducer antenna 179 and one or more electrodes. The induced charge is independent of the frequency at which the voltage V is applied and is generally expressed as follows.

0028<maths num="1"><img id="000002" he="9" wi="22" file="JP5908029B2_D0001.tif" img-format="tif" img-content="drawing" /></maths> In the equation, C is the capacitance between the transducer antenna 179 and one or more electrodes from which charge is induced. A current can be induced in the electrode array 154 by varying the voltage applied to the transducer antenna 179. Specifically, the induced charge of the electrode array 154 is changed by changing the stored charge and the electric field by changing the applied voltage. The change in the induced charge causes the electrode array 154 to generate a current amount (I). This amount of current is proportional to the applied drive frequency as well as the voltage V and the capacitance C as expressed by Equation 2.

0029<maths num="2"><img id="000003" he="14" wi="22" file="JP5908029B2_D0001.tif" img-format="tif" img-content="drawing" /></maths> According to various exemplary embodiments of the present invention, the value (current amount) of the current (detection signal) induced in the electrode array 154, more specifically, the attributes (eg, amplitude, phase, etc.) are measured. , Used to determine the position of converter 175. In other words, when operating in the transducer mode, the sensor controller 152 is configured to determine the position of the transducer 175 based on the attributes of the plurality of detection signals induced in the electrode array 154.

0030FIG. 4 is a block diagram of the converter 175 according to an embodiment of the present invention. The converter 175 includes a converter control device 177 and an antenna 179. The converter control device 177 controls the operation of the converter 175 and may suitably include any type of processing device. In the illustrated embodiment, the converter controller 177 is a pressure sensor 306, a Power Arbitrator 308, a side switch 310, a capacitor 314 (eg, an ultracapacitor, an electric double layer capacitor (EDLC) called a supercapacitor). It is equipped with a Capacitor (ultra capacitor)), a charge input connector 315, a regulator 316, and a Micro Controller Unit (MCU) 318. The power controller 308 and MCU 318 are coupled via a general purpose input / output (312), and the MCU 318 and antenna 179 are coupled via another GPIO.

0031Also referring to FIG. 3 (b), some or all of these components constituting the transducer controller 177 and their required interfaces are mounted on a properly sized circuit board 329 housed in the transducer body 330. Can be done. In the embodiment of the stylus shown in FIG. 3 (b), all the parts except the capacitor 314 are mounted on the board 329 inside the pen-shaped main body 330. In the embodiment shown in FIG. 3B, the pressure sensor 306 is provided near the tip of the stylus, and when the tip is pressed against the detection surface, the pressure sensor 306 detects the pressure on the tip that also functions as the antenna 179. However, in other embodiments, the pressure sensor 306 may be placed further away from the tip via a mechanism or link mechanism that transmits pressure information from the tip to the position of the pressure sensor 306. The side switch 310 is provided so as to be exposed on the side of the pen-shaped main body 330, and functions as a right button and a left button in a mouse device. The charge input connector 315 is exposed at the rear end of the pen-shaped body 330 and is a charging docking station. Station) (not shown) is connected. A capacitor 314 such as a super capacitor is provided at the rear of the pen-shaped main body 330. The antenna 179, which functions as the pen-shaped tip of the stylus-shaped transducer 175 of FIG. 3 (b), can be made of any suitable conductive material and can be formed into any suitable shape. Although the dimensions of the stylus transducer are not limited according to the present invention, in one embodiment illustrated in FIG. 3 (b), the stylus has a length of 120 mm and a diameter of 11 mm.

0032In the illustrated embodiment, the capacitor 314 is provided to function as a power source for the converter 175. Any capacitor, such as a supercapacitor with high energy density, which provides sufficient power to operate the transducer 175 by charging for a predetermined time, may be used. A capacitor with a rated voltage of 3.3V and a capacity of 0.2F will be able to provide sufficient power for most applications. As can be seen from FIG. 3 (b), the diameter of the capacitor 314 defines the diameter of the stylus converter 175. Therefore, by reducing the diameter of the capacitor 314, the diameter of the converter 175 can be made smaller so that it falls within the range of 3-7 mm.

0033The capacitor 314 can be charged from various power sources. For example, as shown, when the transducer 175 is placed in a docking station or other storage area as a device (not shown) associated with this input system, the capacitor 314 is via the charge input connector 315. Can be charged. When the transducer 175 is placed in the docking station, power is delivered via ohmic contact, i.e., from the docking station antenna to the transducer 175, and more specifically to the capacitor 314. In another embodiment, a powering antenna (Powering) provided from the electrode array 154 or separately from the electrode array for this purpose. Capacitor 314 can be charged by receiving an electromagnetic signal from (Antenna). The power supply antenna may be located on or near the electrode array 154. To receive these electromagnetic signals, the transducer 175 may use antenna 179 or a separate antenna specially provided for this purpose. In these embodiments, the transducer 175 can be recharged in use and therefore a smaller capacitor 314 can be used. The capacitor 314 is an example of a power source suitable for use with the converter 175, and other types of power sources such as a storage battery and a cord type power source can be used in the same manner.

0034The pressure sensor 306 is used on the transducer 175, more specifically in the case of a stylus-shaped transducer, to detect the pressure applied to the tip of the transducer. The detected pressure is used to control various operations of the transducer 175 and the combinatorial touch and transducer input systems. In the illustrated embodiment, the pressure sensor 306 is attached to the tip portion so that the pressure at which the tip of the pen-shaped transducer is pressed against the detection surface 104 can be measured. As an example, the detection pressure is used to awaken the transducer 175 from its default sleep mode. By providing the sleep mode and activating the converter 175 only when the tip pressure is detected, the actual operating time of the converter 175 can be reduced and power can be saved. As another example, when the pressure sensor 306 detects a pressure value above a certain threshold in connection with switching to touch mode operation, the combined touch and transducer input system is placed in converter mode. Can be operated with. In yet another example, the pressure sensor 306 is used to indicate the width or strength of the user's stroke, such as a small pressure indicating a thin or light stroke desired by the user, or a large pressure indicating a thick line or strong stroke. be able to. As a means for embodying the pressure sensor 306, various different types of circuits can be used. As an example, a variable resistor whose resistance changes when pressure is applied can be used. Resistance changes are measured and digitized by an appropriate analog-to-digital converter (ADC). It is then sent to the MCU 318 for processing that determines the detected pressure level.

0035The side switch 310 is a switch that allows the user to control the operation of the transducer 175, similar to, for example, right-click and left-click operations of the mouse. The state of the side switch 310 is transmitted to the MCU 318 and is used to control the operation of the converter 175. For example, the side switch can be used to set different operating modes, such as allowing the transducer 175 to be used in different colors or with different types of strokes and the like. Similar to the pressure information obtained by the pressure sensor 306, the switch information of the side switch 310 received along with the converter identification information (ID) is encoded into digital data by the MCU 318 and from the antenna 179 as further described below. It is transmitted to the electrode array 154.

0036The regulator 316 controls the power to the converter 175. It also controls the power supply to the MCU 318. In particular, in the application of a cordless converter powered by a capacitor 314 or a storage battery, it is desirable to minimize power consumption. Therefore, it is preferable that the power regulator 316 is set to the start mode when energized by the normal current drive, and is brought into the sleep mode or the stop mode when the energization is performed by the low current drive. Therefore, the power controller 308 monitors the pressure signal received from the pressure sensor 306 so that the MCU 318 can judge, and when the detection level exceeds a certain threshold value, the regulator 316 is activated from the sleep mode. It is possible to switch to mode and activate the converter 175. Substantial power saving is possible by activating the transducer 175 only when sufficient tip pressure is detected. Various different types of power regulators can be used, including various programmable devices with controllable output levels. The operation of the converter that switches between the sleep mode and the wake-up mode will be described below with reference to FIG.

0037According to some exemplary embodiments of the invention, the microcontroller device (MCU) 318 performs the entire process for the converter 175 and has three functions: the regulator 316 via the power controller 308. Control, supply a signal to the antenna 179 via the MCU 318, and avoid noise by hopping the drive signal frequency and / or encode digital data in the drive signal. According to various exemplary embodiments of the invention, the MCU 318 is a programmable device with a digitally controlled oscillator. This digitally controlled oscillator supplies a signal to the antenna 179. This oscillator performs frequency hopping and frequency shift the signal to produce signals in different frequency ranges corresponding to the coding of digital data (eg, pressure data, switch state data, and pen identification data). Can be controlled to supply to. In another embodiment, the MCU 318 shifts the signal fed to the antenna 179 in amplitude or phase shift in response to the coding of digital data. The MCU 318 controls the timing, duration, frequency, amplitude, and phase of the signal supplied to the antenna 179. Therefore, the electric field generated by the antenna 179 is used by the sensor 150 not only to determine the position of the transducer 175, but also to receive and decode the digital data encoded by the transducer 175. The MCU 318 preferably has a low power mode that reduces the operating current. The low power mode can be applied during the signal transmission time, that is, while no signal transmission is taking place, to reduce the power consumption of the entire converter 175. An example of a low power microcontroller device suitable for use as an MCP318 is the MSP430 microcontroller available from Texas Instruments.

0038FIG. 5 (a) is a block diagram of the sensor 150 with the electrode array 154 and the controller 152 (see FIG. 2). The control device functions to perform signal processing for positioning the object (eg, finger) and the transducer 175, as well as decoding the digital data encoded by the electric field generated by the transducer 175. In the illustrated embodiment, an analog multiplexer (MUX) 410, another analog multiplexer 412, a processing stage 414, an analog-to-digital converter (ADC) 416, and a microprocessor device (MPU: Microprocessor). Unit) 420 is provided. These are the components of the control device 152 for detecting the position indicated by the converter 175 and the digital data. The controller 152 also includes a filter and an analog-to-digital converter (ADC) 418 that together with the multiplexer 410 and the MPU 420 form a capacitive touch detector of the controller 152. An example of a microprocessor device suitable for use as the MPU420 is a Programmable System-on-Chip (PSOC) microprocessor available from Cypress. The configuration of the control device 152 as shown in FIG. 5A is merely an example, and other configurations of the control device 152 are also possible as will be apparent to those skilled in the art. For example, the capacitive touch detection unit and the component for detecting the indicated position of the converter 175 and the digital data can be partially or wholly combined and integrated. In the illustrated embodiment, the MPU 420 is shared by both the capacitive detector and the indicated position of the transducer 175 and the components that detect digital data.

0039The multiplexer 410 selectively couples the electrode array 154 to the capacitive touch detector and / or the indicated position of the converter 175 and the components that detect digital data, depending on the operating mode of the system. The multiplexer 410 can be embodied using a suitable analog multiplexer. These multiplexers are preferably selected to have a relatively low charge injection so as not to significantly disturb the capacitance of the electrode array 154. The multiplexer 410 is coupled to an analog multiplexer 412 included in a component that detects the indicated position of the converter 175 and digital data, a filter of the capacitive detection unit, and an ADC stage 418.

0040In the capacitive detector, the filter and ADC stage 418 measure and appropriately amplify any capacitive changes caused by the object so that the MPU 420 can perform the process of determining the position of the object. , Filter and digitize. To this end, for example, the MPU420 can supply electrical signals to each of the elongated electrodes 154a that make up the first set to form a capacitor with each of the elongated electrodes 154b that make up the second set. is there. The capacitance change in each capacitor formed between the electrodes (154a, 154b) is monitored and measured through the corresponding electrodes of the electrodes 154b that make up the second set. The MPU420 performs the processing necessary to determine the position of the object based on the measured capacitance change. A wide variety of different techniques can be used to facilitate capacitive detection. Each embodiment of the present invention can be realized by using an arbitrary capacitive detection technique. According to one aspect of the invention, the combinatorial touch and transducer input system may be constructed from any suitable capacitive touch sensor to which the function of detecting the indicated position and digital data of the transducer 175 can be added.

0041The analog multiplexer 412, which includes the indicated position of the converter 175 and the component that detects digital data, functions to connect the individual electrodes of the electrode array 154 to the processing stage 414 during converter mode. When each electrode is not connected to processing stage 414, each electrode is selectively terminated (eg, to ground), as will be more fully described below with reference to FIGS. 11 (b) and 11 (c). Direct grounding, termination to grounding through a resistor, or floating (unconnected).

0042The processing stage 414 functions to amplify and filter each detection signal received from the electrode array 154. Therefore, the processing stage 414 can include various amplifiers and filters. An example of the processing device 414 will be described in detail below with reference to FIG. Each amplified and filtered analog signal is then received by the ADC 416 and output digitally from this ADC 416 to the MPU 420.

0043FIG. 6 illustrates one particular embodiment of processing stage 414. In this embodiment, the processing stage 414 includes an amplifier 502, an automatic gain control (AGC) 504, a notch filter 506, a band filter 508 (eg, a wideband band filter), and an alias removal filter 510.

0044Amplifier 502 amplifies the signal received from the selected electrode. Various types of amplifiers may be used, including charge amplifiers, voltage amplifiers, transimpedance amplifiers (current-voltage converters), and longitudinal transimpedance amplifiers.

0045FIG. 7 illustrates an exemplary charge amplifier 600 that can be used as the amplifier 502 of FIG. The charge amplifier 600 includes an operational amplifier (ie, an "op amp") 602 that operates with negative feedback via a capacitor 606. The inverting input of this operational amplifier 602 is connected to the electrode line. The charge amplifier 600 generates a voltage proportional to the charge induced on the electrodes, which voltage is given by Equation 3 below.

0046<maths num="3"><img id="000004" he="12" wi="19" file="JP5908029B2_D0001.tif" img-format="tif" img-content="drawing" /></maths> In the equation, V is the output voltage, Q is the charge induced in the electrode, and C is the capacitance of the feedback capacitor 606. Since all operational amplifiers receive input bias currents and offset bias currents at the inverting and non-inverting terminals, respectively, the charge amplifier of FIG. 7 should have a DC path for these currents to flow. For example, the resistor 607 is provided in parallel with the feedback capacitor 606 and provides a DC path that allows the bias current of the inverting terminal to flow without compromising the characteristics of the charge amplifier, such as that set by the feedback capacitor 606. Generate. This design differs from the longitudinal transimpedance amplifier of FIG. 10 described below. In FIG. 10, the value of the resistor 904 is determined with respect to the feedback capacitor 906 so that the impedance of the feedback resistor 904 is dominant over the impedance of the capacitor 906 in the feedback loop. Appropriate values for feedback resistors and capacitors, such as those used in FIGS. 7 and 10, will be readily determinable by one of ordinary skill in the art.

0047FIG. 8 illustrates an exemplary voltage amplifier 700 that can be used as the amplifier 502 of FIG. The voltage amplifier 700 includes operational amplifiers 702 and resistors 704 and 706. The electrode line is connected to resistor 706.

0048FIG. 9 illustrates an exemplary transimpedance amplifier 800 that can be used as the amplifier 502 of FIG. The transimpedance amplifier 800 includes an operational amplifier 802 and a resistor 804. The inverting input of operational amplifier 802 is connected to the electrode line. The current flowing through the feedback resistor 804 surrounding op amp 802 is converted to voltage.

0049FIG. 10 illustrates an exemplary longitudinal transimpedance amplifier 900 that can be used as the amplifier 502 of FIG. This longitudinal transimpedance amplifier 900 includes an operational amplifier 902, a resistor 904, a capacitor 906, two constant current sources 908 and 909, and a transistor such as an NPN transistor 910. The longitudinal transimpedance amplifier 900 operates in the same manner as the transimpedance amplifier 800 of FIG. 9 in that any current flowing through the feedback resistor 904 surrounding the operational amplifier 902 is converted into a voltage as follows.

0050<maths num="4"><img id="000005" he="6" wi="20" file="JP5908029B2_D0001.tif" img-format="tif" img-content="drawing" /></maths> In the equation, V is the output voltage, I is the current flowing through the feedback resistor 904, and R is the resistance of the feedback resistor 904. The longitudinal transimpedance amplifier 900 uses an NPN transistor 910 to isolate and separate the input capacitance of the electrode line from the feedback resistor 904 of the transimpedance amplifier 900, resulting in a higher without sacrificing bandwidth or signal-to-noise ratio. It is beneficial in that it makes transimpedance gains feasible. The longitudinal transimpedance amplifier 900 has also improved stability by incorporating a feedback capacitor 906 in parallel with the feedback resistor 904 to control the noise gain on the high frequency side.

0051Providing the transistor 910 in front of the transimpedance (current-voltage conversion) is known as a longitudinal transimpedance amplifier. Since the NPN transistor 910 is configured as a common base current buffer, it allows the current flowing into the emitter (E) to flow through this transistor 910 and outflow to the collector (C). The current is then converted into a voltage signal by a transimpedance amplifier. The emitter (E) of the NPN transistor 910 has an equivalently small signal resistance given by the following equation.

0052<maths num="5"><img id="000006" he="15" wi="25" file="JP5908029B2_D0001.tif" img-format="tif" img-content="drawing" /></maths> In the equation, k is the Boltzmann constant, T is the temperature, q is the basic unit of charge, and Ic is the bias current flowing through the NPN transistor. The resistance r is determined from the electrode capacitance, and an RC constant that can limit the bandwidth of the transimpedance amplifier is set. Therefore, the two equal constant current sources 908, 909 are set with an appropriate bias current so that the emitter resistance r is sufficiently small to allow the signal captured by the electrodes to pass through the transimpedance amplifier. In another embodiment, one current source may be used to achieve the same effect. In this case, there is only one current source and the bias current flows through the transimpedance amplifier. This saturates the transimpedance amplifier with sufficient gain and forces the detection of a large DC offset that erases the desired signal. By using two matched constant current sources 908, 909, as shown, the bias current injected into the NPN transistor 900 is also captured by the transimpedance amplifier and guaranteed to flow from the transimpedance amplifier.

0053Returning to FIG. 6, the amplification signal output from the amplifier 502 is supplied to the automatic gain control (AGC) 504. Using the feedback signal from the MPU420, the AGC504 automatically adjusts the output of the amplifier 502. The AGC504 adjusts the level so that the dynamic range of the signal finally sent to the ADC416 is consistent with its full-scale reference. This can reduce the digitization noise that can occur when a relatively weak signal is received by the electrode array 154.

0054The output of the AGC504 is supplied to the notch filter 506. The notch filter 506 is provided to remove noise spikes such as noise spikes caused by power line noise captured by the electrode array 154. Preferably, a 50 / 60Hz notch filter can be used to remove typical power line noise.

0055The output of the notch filter 506 is supplied to a band filter 508 such as a wide band band filter. The band filter 508 blocks or eliminates other frequencies and allows only a predetermined frequency range to pass.

0056The output of the band filter 508 is supplied to the alias removal filter 510. The alias removal filter 510 is a filter that guarantees that the sampling signal by the ADC is not aliased or distorted by reducing noise above a predetermined frequency. The alias removal filter 510 is generally implemented using a filter with a very sharp cutoff frequency. The output signal of the alias removal filter 510 is supplied to the ADC 416.

0057As illustrated in FIG. 6, the processing stage 414 amplifies and filters each signal received by the electrode array 154. Returning to FIG. 5 (b), the output of the processing stage 414 is supplied to the analog-to-digital converter (ADC) 416. The ADC 416 digitizes the analog output of the processing stage 414. In one embodiment, the ADC 416 has a sampling frequency of 1 MHz. This is a sufficient sampling rate to avoid aliasing when the transducer 175 transmits signals at frequencies up to 250 kHz.

0058The digitized output of ADC416 is supplied to MPU420. The MPU420 performs a process of determining the indicated position of the converter 175 from the received signal in the same manner as decoding encoded digital data (for example, pressure data, switch state data, and pen identification data) from the received signal. Execute. It should be noted that each example used for encoding the signal by the converter 175 into digital data, scanning and decoding the instruction signal by the converter 175, determining the instruction position by the converter 175, and decoding the digital data. The process will be described later with reference to FIGS. 11 (a) to 16.

0059In various other embodiments of the invention, the transducer 175 is via other RF devices, such as via a Bluetooth (R) device conforming to the IEEE 802.11 standard, including Bluetooth (Bluetooth®) and ZipBee protocols. By using wireless technology, digital data (eg, pressure data, switch state data, and pen identification data) can be transmitted to the sensor 150.

0060As described above, the combinatorial touch and transducer input system may be configured to alternate between these two modes by switching the touch detection mode and the transducer detection mode to each other in a continuous sampling cycle. To this end, the controller 152, and more specifically the MPU 420, is configured to control the multiplexer 410 to alternate between touch detection and transducer detection. In another embodiment, the operating mode may be selected by the user of this system. For example, the sensor 150 may include a switch that can be operated by the user to select one of the two modes. As in another embodiment, if the system operating in transducer mode is receiving digital data from transducer 175 indicating that pen pressure above a predetermined threshold has been detected. , Operates in converter mode. As mentioned above, the pressure sensor 306 can be used to detect the tip pressure applied to the stylus-shaped transducer 175 and activate the transducer only when the pen pressure exceeds the threshold. At that time, the converter 175 can send information indicating the pressure value and the activation mode to the sensor 150. For example, digital data can also be encoded by the electric field generated by the converter 175 and transmitted to the sensor 150. Upon receiving digital data indicating pen pressure above the threshold (after decoding if necessary), in converter mode, controller 152 resets its timer for a given period of time. It is possible to automatically continue the operation in the converter mode without switching to the touch mode.

0061Explaining FIG. 5 (b) here, in some embodiments of the present invention, the electrode array 154 is divided into a touch mode region (1) and a converter mode region (2). The control device 152 is configured to operate simultaneously in the touch mode of the touch mode area (1) and the converter mode of the converter mode area (2). For this purpose, the electrode array 154 needs to be properly connected to the multiplexer 410. In the illustrated embodiment, the electrode array 154 is divided into four quadrants, at time 1 two of which 422 form a touch mode region (1) and the other two quadrants 424 form a transducer mode region (2). ) Is formed. A control device for selectively switching between the touch mode region (1) and the converter mode region (2) so that predetermined positions on the electrode array 154 alternately exist in the touch mode region and the converter mode region. 152 can be configured. For example, in FIG. 5 (b), at time 2, the two quadrants 422 that previously formed the touch mode region now form the transducer mode region (2), while previously forming the transducer mode region (2). The touch mode area and the converter mode area are switched so that the other quadrants forming the) form the touch mode area (1) at present. By alternately transitioning between the state of time 1 and the state of time 2, the control device 152 can operate the touch mode and the converter mode at the same time. Any position on the electrode array 154 alternates between the touch mode region and the transducer mode region. In the illustrated embodiment, the touch mode region and the transducer mode region each consist of two quadrants, but each mode region may consist of one region or three or more subregions. Further, the shape of each region and sub-region is not limited to that shown in FIG. 5 (b), as in the pattern in which a large number of regions and sub-regions are combined. For example, each region or sub-region may have an elongated shape to form a stripe and may be arranged parallel to each other.

0062FIG. 11 (a) is a flowchart illustrating an example of a process executed by the sensor control device 152 to scan each signal from the electrode array 154 in the converter mode. In step 1001, multiplexers 410 and 412 are set to receive signals from the first horizontal ITO line, eg, the first Y electrode. In step 1003, the selected horizontal ITO line is scanned. In step 1005, it is determined if there are other horizontal ITO lines to scan. If so, in step 1006, the next horizontal ITO line is selected, and the process returns to step 1003, and the selected next horizontal ITO line is scanned. If it is determined in step 1005 that there are no more horizontal ITO lines, then in step 1007 the multiplexers 410, 412 to receive the signal from the first vertical ITO line, eg, the first X electrode. Is set. In step 1009, the selected vertical ITO line is scanned. At step 1011 it is determined if there are other vertical lines to scan. If so, at step 1013, the next vertical ITO line is selected and back to step 1009, the next selected vertical ITO line is scanned. If it is determined in step 1011 that there are no more vertical ITO lines, i.e. that the entire electrode array 154 has been scanned, then the process proceeds to step 1015 and the processing stage 414 of controller 152. The signal of the scan data is used to adjust the gain of the AGC504 in. According to various exemplary embodiments of the invention, each step of FIG. 11 (a) is performed simultaneously with other software performed by the MPU 420. This ensures that a constant flow is formed in the signal sample arriving from the electrode array 154.

0063Next, FIGS. 11 (b) and 11 (c) will be described. Referring to FIG. 11 (a), when scanning the electrodes described above, the capacitive response of the detection electrode is improved by selectively terminating each electrode adjacent to the electrode on which the signal is detected. It was found that the signal-to-noise ratio was improved and a stable signal was generated. The details are shown in Fig. 11 (b). One of the elongated electrodes constituting the second set, electrode 426, is in the signal detection state, while each adjacent electrode of the elongated electrodes 154b constituting the second pair is all terminated to the ground via the resistor R. doing. Further, all the elongated electrodes 154a constituting the first set are grounded. As used herein, "selectively terminated" means grounded through zero or low impedance, suspended (ie, disconnected, or grounded at high or infinite impedance). , And any of a plurality of selected states, including a state terminated to ground via a resistor or another electronic device having a predetermined impedance.

0064In other embodiments, only two or more of the adjacent electrodes can be terminated either directly or through a resistor (or floating or grounded). In the example of FIG. 11 (b), all adjacent electrodes of the elongated electrodes 154b that make up the second set are terminated via a resistor "R". For example, FIG. 11 (c) shows another exemplary embodiment according to the invention, in which one of the elongated electrodes 426 constituting the second set was detected, while both sides of the electrode 426. Two adjacent electrodes 427 (four adjacent electrodes in total) located at are also suspended. The remaining electrodes are grounded. In this embodiment, these adjacent electrodes 427 are not grounded to ground via another device such as a resistor. In another embodiment, three or four adjacent electrodes on one side of the electrode 426 may also be suspended or terminated via a resistor with the remaining electrodes grounded. Contrary to conventional knowledge that if all adjacent electrodes are not grounded, cross-coupling will occur between adjacent electrodes, in some applications the adjacent electrodes will be suspended or terminated via a resistor. By doing so, the capacitive coupling between the transducer 175 and the electrode (426) in the signal detection state is surprisingly improved.

0065On the other hand, in other applications, grounding all adjacent electrodes reduces the capacitive coupling between the adjacent electrodes and improves the capacitive response of the electrodes in the signal detection state. This can be true, for example, when high frequency signals are used or when the electrodes are very thin and have a width of about 1 mm. Appropriate methods for selective termination described above (eg, how many adjacent electrodes should be suspended, terminated through a resistor, or grounded directly) are specific electrode configuration patterns based on simulation methods. It is possible to derive for. As a specific example, as illustrated in FIG. 13 (b), each electrode is terminated either directly (ie, with zero impedance) or grounded through a resistor, to a floating state (ie, infinite). The curve width of the signal response is controlled by changing to (grounded) through the impedance of. Controlling and optimizing this curve width will be useful in performing the curve fitting procedure, also described below, to determine the position of the transducer.

0066The above description relates to various embodiments of the present invention in which the transducer 175 and the sensor 150 are electrically (capacitively) coupled based on the electric field generated by the transducer 175. In other embodiments, they can be magnetically coupled based on the magnetic field components of the electromagnetic field generated by the transducer 175. FIG. 11 (d) illustrates a sample configuration of a sensor 150 ́ suitable for examples using magnetic coupling. In FIG. 11 (d), in the (vertical) electrodes 154b constituting the second set, one side of each electrode is a wiring T.₁Is short-circuited together. The other side of each electrode is switched so that none of the electrodes 154b constituting the second set can be grounded or connected to a detection line L connected to controller 152 (not shown). S₁~ S₁₄It is connected to the. In another example, two or more of the electrodes 154b that make up the second set or the electrodes 154a that make up the first set can be connected to the detection line L at the same time. In the illustrated example, only one electrode 154b'is connected to the detection line at the same time. In FIG. 11 (d), the switch S for the electrodes 154b constituting the second set₁~ S₁₄However, a similar switch is connected to the electrodes 154a that form the first set.

0067Closed switch S, as shown in Figure 11 (d)₃And S₈The second electrode 154b and the fourth electrode 154b (from the left side in FIG. 11 (d)), and the wiring T connecting these two electrodes.₁, A loop surrounded by a detection line L (connected to controller 152) and a return path P (from controller 152) is formed. That is, this configuration forms a loop through the grounded electrode 154b . Any magnetic flux flowing through the region enclosed by this loop produces an electromotive force that can be considered as a current or voltage source connected in series with this loop. By connecting the loop to a voltage amplifier as shown in FIG. 8 or a transimpedance amplifier as shown in FIGS. 9 and 10, the signal induced in the loop by the magnetic transducer can be detected. The position of the magnetic transducer can be calculated and determined based on the detection of signals across a large number of loops. The magnetic transducer is shown in FIG. 3 (b), except that it has a loop (or coil) antenna capable of generating a stronger magnetic field when compared to the typical pin-shaped antenna 179 shown in FIG. 3 (b). It is configured in the same way as the converter shown in b).

0068In FIGS. 11 (b), 11 (c) and 11 (d), the electrodes 154a constituting the first set are shown as "ITO Bottom", and the electrodes constituting the second set are shown. Although 154b is shown as the "ITO Top", the orientation of the top and bottom of each electrode is not so limited by the present invention.

0069As described above with reference to FIGS. 5 (a) and 6, each signal sequentially selected by the multiplexers 410 and 412 is amplified by the amplifier 502 and amplitude adjusted by the AGC 504, notch filter 506, band filter 508. , And are filtered by the alias removal filter 510 and converted to digital values by the ADC 416. The MPU 420 is then configured to filter each digital value received from the ADC 416 according to various exemplary embodiments of the invention. Digital filtering can be realized by a processor different from MPU420. Specifically, the notch filter 506, the band filter 508, and the alias removal filter 510 substantially remove noise, but noise that cannot be completely removed may remain. Therefore, it is preferred that the sensor controller 152 use digital filtering techniques in the MPU 420 or another processor to remove this residual noise from each digital value output from the ADC 416. Any suitable infinite impulse response (IIR) Response) or Finite Impulse Response (FIR) filters may be used.

0070FIG. 12 illustrates the procedure for digital filtering. Although the digital filtering procedure can be realized by another processor, it is preferable that the digital filtering procedure is realized as a software process by the MPU 420. In the illustrated embodiment, the digital filtering procedure comprises three channels for filtering. Each channel corresponds to one of a number of frequencies in which an electric field can be generated by the transducer 175. In the illustrated embodiment, the transducer 175 is configured to selectively transmit at any of the three frequencies. For this reason, the digital filtering procedure includes three corresponding channels, although other embodiments may include more frequency channels. Each filtering channel has a different pass frequency (F)₁, F₂, F₃), A band filter, a rectification stage, and a low frequency filter. Generally, the filter frequency is selected to filter out noise from known proximity noise sources, such as noise from proximity LCD screens. Each of the outputs of the three band filters is rectified and fed to the corresponding low frequency filter. By filtering the remaining noise by filtering each digital value in the low frequency range, related attribute (for example, amplitude, phase, etc.) information is extracted from each input digital value. Therefore, the output of the digital filtering determines the position of the converter 175 and obtains an accurate reference for decoding the encoded digital data from the signal received from the converter 175.

0071According to one aspect of the invention, two or more frequency channels are used for good noise rejection. For example, some LCD screens emit a signal (noise) with a sharp peak at a given frequency. If one of these frequencies is the same as the frequency used by the converter 175, it can be switched to another frequency valid for the converter 175. Therefore, according to one embodiment of the invention, the controller 152 for the sensor 150 is configured to determine the signal-to-noise ratio for each of a number of frequency channels, with the maximum signal-to-noise ratio. The frequency channel to have is selected as the receive channel or as part of the calibration process at design time. As described below, it is also possible for the controller 152 to send digital data indicating the selective receive channel to the converter 175 in the converter mode. As soon as such digital data is received and decrypted, the transducer 175 begins transmitting on the selected receive channel. According to another embodiment of the invention, when two or more combined touch and transducer input systems are used, for example in close proximity to each other, to avoid cross-coupling between the two or more systems. Thus, the transducers of these systems are configured to transmit electric fields at different frequencies, or at frequencies composed of different pairs.

0072As described above, the position of the converter 175 is determined based on the measurement attributes (for example, amplitude, phase, etc.) of the plurality of detection signals induced in the electrode array 154 by the electric field generated by the converter 175. For example, the amplitudes of multiple signals induced in each of the multiple electrodes can be measured and compared to each other to determine the maximum amplitude. The position of the transducer 175 is determined based on the general idea that the signal with maximum amplitude is induced at the electrode closest to the transducer 175. In other embodiments, the phases of the multiple signals induced in each of the multiple electrodes can be measured and compared to each other to determine the position of the transducer 175. For example, for a 300MHz transducer signal, the phase difference between the signals induced by two electrodes 5 cm apart would be 18 °. Their phase can be obtained by digitizing each signal using an ADC operating at 600 MHz. By measuring the phase shift at each electrode, the relative movement of the transducer with respect to each electrode can be determined. For example, in the above example, if the transducer moves 1 cm away from the electrode, the phase of the signal induced at this electrode will shift by 3.6 °. In this method, only the relative movement of the transducer with respect to each electrode is known. By periodically changing each frequency of the converter signal, it is possible to detect and compare the timing at which different electrodes detect the phase shift. The electrode that first detects the phase shift after frequency change is the electrode closest to the transducer. After that, the absolute position of the converter can be continuously determined by detecting the phase shift at the other electrodes as well. The same frequency is then used to monitor the phase shift at different electrodes. The relative movement of the transducer with respect to each electrode is determined before the absolute position of the transducer changes to the next determinable frequency.

0073According to various exemplary embodiments of the invention, the position of the transducer 175 is determined based on the attributes (eg, amplitude, phase, etc.) of each signal induced in the electrode array 154 and then converted to digital values and filtered. Curve fitting techniques are used to determine. For this, the digital value in the MPU420 is used, or the main processor included in the host device (for example, a personal computer incorporating the combined touch and converter input system of the present invention as an input / display system: PC), etc. The MPU420 is configured to perform curve fitting in collaboration with one or more processors. If the curve fitting process is concentrated, such a distributed process can be used for some applications. In this case, after moving each signal obtained by measuring and filtering the signal induced in the electrode array 154 from the MPU 420 to the processor of the host system for processing, for example, a USB or RS232 interface (see FIG. 5 (a)). Can be returned to MPU420 via a series interface such as.

0074Any curve displayed with the appropriate parameters can be used for curve fitting. According to various exemplary embodiments of the present invention, a transducer having a specific tip shape that also functions as an antenna and an electrode having a specific electrode configuration pattern (that is, the shape of each electrode and the arrangement pattern of the electrode array). It is possible to empirically obtain suitable curves for any combination touch and transducer input system with an array. Determining the indicated position by a converter based on curve fitting is capable of obtaining a curve suitable for virtually any combinatorial touch and converter input system, and is specific combinatorial touch and transform. The curves obtained for the instrument input system are beneficial in that they are reliably applicable to the same combinatorial touch and converter input systems that are mass-produced. The reason for this is that curve fitting techniques are powerful enough to explain the usual changes expected in the manufacturing process of a system, such as the ITO manufacturing process. Because these curves can be calibrated to a wide variety of different electrode shapes and array patterns, this technology includes electrodes, including those shapes and configurations originally designed for capacitive touch detection. Facilitates the use of many different shapes and configurations of arrays.

0075FIG. 13 (a) is a flow chart illustrating a sample process used to determine the position of the transducer based on the curve fitting technique according to one embodiment of the present invention. In step 1300, when the transducer 175 is placed in a number of known locations throughout the electrode array, signal data induced in the electrode array 154 is collected. At step 1302, the parameterized curve that best fits the collected signal data is defined. These two steps can be performed at design time and the defined curve is then stored in controller 152 of sensor 150. In step 1304, the signal data induced in the electrode array 154 by the transducer 175 in the transducer mode is collected, the position of the transducer is unknown to the controller 152. In step 1306, the indicated position of the transducer is determined by fitting the data collected in step 1304 to the defined curve. Each of these steps is described in detail below.

0076According to each exemplary embodiment of the invention, two matching curves can be obtained. In this case, in some applications, the same curve can be used for each of the X- and Y-positioning. That is, one curve is for X-positioning and the other curve is for Y-positioning. For curve fitting in each of the X and Y directions (columns and rows of the electrode array, respectively), the attributes of each signal induced in the X and Y electrodes are empirically or theoretically established. One experimental method of setting attributes involves scanning the transducer across the electrode array 154 using a robotic arm or other suitable tool. The robot's arm is commanded to have a known tilt (eg, the angle formed between the transducer axis on the XZ plane and the line perpendicular to the detection plane during the x-position scan), and It can be moved to a known position using a known height above the detection surface. During the X-position scan, the transducer moves between and across the electrodes of the electrode array until good coverage of the entire electrode array is achieved, and the attributes of each signal induced in the X electrode (eg, eg). Amplitude, phase, etc.) are continuously and automatically recorded. As the transducer moves in the X and Y directions, the tilt and / or height of the transducer can also change. For example, for 20 X electrodes, 2,000 transducer positions (with tilt and / or height) can be used to record each attribute of each signal induced in the X electrode. The actual number of measurements required will generally depend on the constitutive symmetry of the electrode array 154. Given the symmetry, the measurement data recorded for the portion of the electrode array 154 can be used to estimate the measurement data for the corresponding portion of symmetry (step 1300 in FIG. 13 (a)). The same process may be repeated for the Y-position scan.

0077Once all measurement data for the X and Y electrodes have been empirically or theoretically set, each position (and slope / height) of the transducer 175 is due to the electric field generated by the transducer at that position. The data can be arranged to be a set of measurement data associated with the attributes of each signal induced in the X and Y electrodes.

0078The data is then applied to the appropriate mathematical equation used as a curve fitting formula. In other words, a curve fitting formula, that is, a parameterized curve that fits the data is set. Possible curves that can be used are polynomials, rational polynomials, and combinations of trigonometric, logarithmic, and exponential functions. For very simple geometries, linear linear interpolation may be sufficient. Rational polynomials can make good compromises between computational accuracy and speed. For an X electrode consisting of the same rectangular conductor, a polynomial can be defined, for example, as follows.

0079<maths num="6"><img id="000007" he="17" wi="54" file="JP5908029B2_D0001.tif" img-format="tif" img-content="drawing" /></maths> The above formula assumes that the i-th electrode in a series of X-electrodes is the center electrode, and the prediction on this i-th electrode when the transducer crosses this i-th electrode from left to right. Examine the amplitude. In the equation, x represents the distance from the center of this i-th electrode. Also, x &lt;0 indicates that the transducer is to the left of the center of the i-th electrode, x&gt; 0 indicates that the transducer is to the right of the center of the i-th electrode, and x = 0 indicates the transform. Indicates that the vessel is in the center of the i-th electrode. This rational polynomial generally has a peak at x = 0 when the transducer is at the center of (ie, directly above) the i-th electrode, and when the transducer moves to the left or right of the i-th electrode, the i-th. The amplitude of the electrodes in is reduced. An exemplary curve based on Equation 6 is shown in Figure 13 (b). In the above formula, the values a, b, c, d, e and f are calibration parameters empirically determined for the tip shape and electrode configuration parameters of the particular transducer in use. In this example, since each electrode of the electrode array 154 is configured the same, the same curve can be generated for each of the X electrodes. Although not required in all cases, in general, these calibration parameters are defined separately for the X and Y electrodes (generating two curves for the X and Y electrodes respectively). It will be. Equation 6 is an example of a rational polynomial that can be used. Other polynomials, or combinations of functions, may also be used. (Step 1032 in Figure 13 (a)).

0080Using a selected curve fitting formula (or parameterized curve) and empirically determined calibration values, the MPU 420 easily locates the converter 175 by adapting the input data to a given curve. can do. This second curve fit can be performed using a variety of different techniques. For example, the position of the transducer can be determined by minimizing the curve fitting formula and the sum of squares between the measured amplitudes. An example of this technique involves solving the following mathematical formulas.

0081<maths num="7"><img id="000008" he="17" wi="64" file="JP5908029B2_D0001.tif" img-format="tif" img-content="drawing" /></maths> In this example, to determine the X position of the transducer, x_1,x_2, x_3,x_4,x₅The amplitude induced in a series (or multiple) X electrodes such as A_1,A_2,A_3,A_4,A₅Is measured and entered in the above formula. Here, p (x) is the curve fitting formula described above. X electrode x₃When is selected as the center electrode, x₃Converter position x with respect to_pen(For example, center x₃Negative value on the left side of and center x₃The positive value to the right of) is the value x that minimizes the sum by solving the above formula._penIt can be determined by determining. This process is then x_6,x_7,x_8,x_9,x₁₀Etc. can be repeated for the X electrodes that make up another set. Similarly, this step has the value y_penIs repeated in the Y direction to find. The exact position of the transducer can be determined by performing curve fitting on the X and Y positions (steps 1304 and 1306 in FIG. 13 (a)).

0082Another technique for adapting incoming amplitude measurement data to a defined curve uses the longest distance between any two points. An example of this technique requires solving the following formula.

0083<maths num="8"><img id="000009" he="14" wi="64" file="JP5908029B2_D0001.tif" img-format="tif" img-content="drawing" /></maths> This technique minimizes the longest distance between any two points x_penAnd also seek the best fit considering the worst case. This technique can be useful if the resulting curve has a very flat response.

0084As another example, techniques such as the Levenberg-Levenberg method and the Gauss-Newton method can be used to quickly determine the minimum value as in formulas 7 and 8 above. is there. These techniques are generally x_penIt starts with the initial estimate for, and then uses the derivative of p (x) to improve the estimate. X until the minimum is improved even a little_penThe process is repeated while adjusting the estimated value for. At this point, the minimum value is calculated and x_penIs determined. Another form of fitting algorithm uses a two-minute search method. In this case, a plausible starting value is chosen, the value is searched backwards and forwards, starting only with the electrode strip difference and subdividing this difference until the best answer is obtained. This technique may be useful for those for which the Riebenberg-Marquardt method or the Gauss-Newton method is inappropriate for a particular application. As another example, 2D (two-dimensional) processing that fits in the XY directions at the same time can be used.

0085As mentioned above, the attributes of the signal induced in the electrode array 154 can be measured while varying the tilt and / or height of the transducer. Therefore, it is possible or adjustable to obtain a parameterized curve that further describes other data such as the slope and / or height of the transducer. The height of the transducer above the detection surface (or "hover") can be determined, for example, by solving the following equation.

0086<maths num="9"><img id="000010" he="17" wi="71" file="JP5908029B2_D0001.tif" img-format="tif" img-content="drawing" /></maths> In this example, with the amplitude Ai detected at the i-th electrode (x)₄7 X electrodes are used (with) as the center electrode. Also, h is the height. x₄Converter for x_penThe X position and height h of are the values x that minimize the sum_penAnd h are determined by determining. In the above formula, the signal strength decreases in proportion to 1 / h as the converter moves away from the detection surface.

0087In another example, the slope of the transducer can be parameterized by the following formula, including trigonometric functions, suitable for use in magnetic coupling embodiments.

0088<maths num="10"><img id="000011" he="31" wi="138" file="JP5908029B2_D0001.tif" img-format="tif" img-content="drawing" /></maths> In this equation, P_tiltIs the tilt angle with respect to the axis orthogonal to the detection plane in the X direction, W_itoIs the width of one electrode loop.

0089Another variant of this technique allows weighting of curve fitting to improve accuracy. This is generally done by weighting these higher intensity signals by a larger amount, as higher intensity signals generally have a higher signal-to-noise ratio. X at the center of the electrode with the strongest signal_penIt may be desirable to start with an initial estimate for. This increases the probability that the actual minimum value will be obtained by the search algorithm.

0090As used herein and as confirmed by the description above, the terms "curve fitting" or "fitting" constitute one or more curves that best fit the "test" data. And then it is related to one or more of the wide range of techniques used to use that one or more curves to process "real" data. Various examples of fitting a defined curve to the actual data or fitting the curve through an iterative process are disclosed by minimizing the error between the curve and the actual data (eg, sum of squares). However, in other examples, non-repetitive steps may be used. For example, a least-squares linear regression can be used to obtain good fit without iteration and without the need to minimize errors. Some positioning data can also be sacrificed in exchange for faster algorithms. For example, in an electrode array with elongated electrodes with a good signal-to-noise ratio, it is possible to position the transducer using a simple linear interpolation method between the two electrodes with the highest amplitude. ..

0091As mentioned above, according to various exemplary embodiments of the invention, the transducer controller 177 uses frequency hopping technology to select electric fields at multiple frequencies, more specifically at successively different frequencies. Generate. Specifically, in various embodiments of the present invention, the MCU 318 of the transducer controller 177 comprises an on-board digitally controlled oscillator configured to selectively generate signals supplied to the antenna in different frequency ranges. When hopping from one frequency to another in order to improve the noise rejection capability, the frequency of the electric field generated by the antenna 179 changes accordingly. Also, these different frequencies can be used to encode the digital data and transmit it from the transducer 175 to the electrode array 154 and thus to the sensor controller 152. Frequency shift keying (FSK) suitable for encoding and transmitting digital data related to the converter 175, such as pressure data, switch state data, and converter identification data (ID). Keying) technology is available. The converter identification data can be useful in identifying a particular transducer. For example, when the sensor 150 is used in a POS (Point-of-Sale) system and different distributors carry different converters 175, the sensors are for converter identification received from the agent's transducers 175. Based on the data, the special sales agent who is entering the data can be automatically identified. As another example, when multiple combined touch and transducer input systems according to the invention are used in close proximity to each other, only the signal received from the desired converter 175 can be processed (other transducers). Being able to identify the transducer 175 (apart from) would be desirable for each sensor.

0092According to one aspect of the invention, the frequency used for communication between the transducer 175 and the sensor 150 may be defined by dividing a known (fundamental) frequency. This method has the advantage of avoiding fundamental frequency harmonics and providing better noise rejection. In one example, the transducer 175 operates in two modes. The first mode is a low power mode that can generate four frequencies. The second mode is a high power mode that consumes more power than the low power mode but results in a large number of frequencies that are not harmonics of the fundamental frequency. Table 1 below represents the possible frequencies that can be used by the transducer according to one embodiment of the present invention.

0093<tables num="1"><img id="000012" he="90" wi="148" file="JP5908029B2_D0001.tif" img-format="tif" img-content="drawing" /></tables> In each of the low power mode and the high power mode, the usable frequency is determined by dividing the fundamental frequency (for example, 500 kHz and 2 MHz). Table 1 above merely shows an example of one set of different frequencies available according to one embodiment of the present invention, and other sets of different frequencies are selected for use in other embodiments of the present invention. You may. Various other methods may be used to select a set of different suitable frequencies, such as using a phased locked loop (PLL).

0094The configuration of the PLL is well known. FIG. 13 (c) shows the configuration of a sample PLL suitable for use according to the examples of the present invention. This PLL includes a reference frequency (Rf) 1310, a voltage controlled oscillator (VCO) 1312, a phase detector 1314, and a loop filter consisting of an operational amplifier 1316 and two resistors 1318a and 1318b. To generate different frequencies from the reference frequency (Rf), the PLL is equipped with one or more dividers (M divider 1320 and N divider 1322 in the embodiment shown). The PLL can generate each frequency specified by the M / N based on the reference frequency (Rf). This makes it possible to generate a wide range of frequencies that share the fundamental frequency. For example, if N can be selected in the range 1 to 16, 16, 15, 13 and 11 can be selected as divisors in the N divider 1322. If 11 or 7 is selected as the divisor in the M divider 1320 and the reference frequency (Rf) is 500 kHz, the following output frequencies can be generated.

009511/16 * 500 KHz = 343.75 KHz 11/15 * 500 KHz = 366.67 KHz 11/13 * 500 KHz = 423.08 KHz 7/11 * 500 KHz = 318.18 KHz Since the PLLs can generate frequencies in a range close to each other, a narrowband filter (508) can be used for the analog processing stage 414 in the sensor controller 152. This has the effect of increasing the signal-to-noise ratio before the signal is digitized.

0096In one embodiment, the transducer 175 is configured to generate four different frequencies within the specified range (eg, 100kHz, 125kHz, 166kHz and 250kHz in the "low power" mode of Table 1). The converter controller 177 is configured to switch between these four different frequencies or encode digital data with frequency shift as needed for noise rejection. Various techniques can be used to encode digital data using frequency hopping. For example, any suitable frequency shift keying (FSK) technique may be used. Additional or alternative, any suitable Amplitude-Shift Keying (ASK) technology, Phase-Shift Keying (PSK) technology, or any suitable Amplitude-Shift Keying (ASK) technology to encode digital data. More complex coding systems, such as Quadrature Amplitude Modulation (QAM) systems, may be used to encode digital data.

0097As one particular example, Manchester code can be used to encode digital data. In this Manchester code, a high-to-low frequency change sends a "1", while a low-to-high frequency change sends a "0". Table 2 below illustrates a sample data coding scheme based on Manchester code.

0098<tables num="2"><img id="000013" he="30" wi="136" file="JP5908029B2_D0001.tif" img-format="tif" img-content="drawing" /></tables> As shown above, three consecutive changes from high to low (111) indicate the start of frame (SOF), and three consecutive changes from low to high (000) indicate the end of frame. Indicates (EOF). Between SOF and EOF, any three changes of "001" send "0" and any three changes of "011" send "1". These digital data (SOF, 0, 1, and EOF) are transmitted in a data frame configuration. An example is shown in FIG. A data frame as shown in FIG. 14 has its own start bit sequence (SOF) and end bit sequence (EOF). Therefore, it is possible to have different lengths. The data frame in Figure 14 contains the frame start (SOF) block 950, followed by the data type block 952 (2 bits), the payload data block 954 (3 to 24 bits), and finally the frame end (EOF). ) Includes block 956. Table 3 below shows an example of the data frame format for each data type.

0099<tables num="3"><img id="000014" he="51" wi="141" file="JP5908029B2_D0001.tif" img-format="tif" img-content="drawing" /></tables> In the above example, the 2 bits of "00" indicate the "pen identification" data, followed by the 24 bits of the unique pen identification number. The 2 bits of "01" indicate the "switch state" data, followed by the 3 bits indicating the state of one of the up to three switches. Finally, the 2 bits of "10" indicate the "pressure" data, followed by the 8 bits of the detected pressure value. Only three types of data are shown, but more or different types of data may be defined and digitally encoded. For example, define data obtained from any other sensor provided on the transducer 175, such as a tilt sensor or rotation sensor, or the operating mode of the transducer 175 (eg, "wakeup mode" or "sleep mode"). It may be digitally encoded.

0100Table 4 below shows an example of a data frame containing switch state data.

0101<tables num="4"><img id="000015" he="25" wi="148" file="JP5908029B2_D0001.tif" img-format="tif" img-content="drawing" /></tables> In the above example, first, three consecutive frequency changes from high to low (111) indicate the start of the frame (SOF). The next two bits of "01" are generated by the frequency changes of "001" and "011", indicating that this data frame is "switch state" data and the payload data is 3 bits long. The following 3 bits of "100" are generated by the frequency changes of "011", "001" and "001", respectively, indicating that the first switch is pressed. Finally, three consecutive low to high frequency changes (000) indicate end of frame (EOF).

0102The speed of data transmission provided by the method described above depends on the speed of frequency hopping. For example, if four frequencies can be used to generate frequency hopping every 250 μs, the system can transmit data at a throughput of 1 kbit / s.

0103The present invention is not limited to the special examples described above, and various other digital coding or modulation techniques may be used as with other data frame types. For example, other coding techniques with advanced features such as error correction (eg, Reed-Solomon coding techniques) may be used.

0104FIG. 15 is a flowchart of an embodiment of the present invention. Beginning with the process of encoding digital data and transmitting it to the sensor 150, the converter controller 177, more specifically, the microcontroller device (MCU: Micro Controller). unit) 318 shows an exemplary process that should generally be performed. After the transducer wakes up, in step 1060 the timer is set to sleep. Once the timer is set to sleep and a predetermined time has elapsed, that is, when the time set in the timer is reached, the transducer goes to sleep. In step 1062, the pressure applied to the tip of the pen is detected by the pressure sensor 306. In step 1064, it is determined whether or not the pressure applied to the pen tip detected in step 1062 exceeds a predetermined threshold value. If so, go to step 1066 and the timer will be reset to sleep. Then, in step 1068, the pressure applied to the pen tip is encoded as digital data and transmitted to the sensor 150. Similarly, in step 1070, the state of the side switch is encoded as digital data and transmitted to the sensor 150. In step 1072, it is determined whether the side switch state has changed. If so, step 1074 resets the timer to sleep. Then, in step 1076, the pen identification information (ID information) is encoded as digital data and transmitted to the sensor 150. At step 1078, whether or not the timer has reached a predetermined time is determined, for example, by the timers reset at steps 1066 and 1074. If not, the process returns to step 1062, the pressure applied to the pen tip is detected again and the process itself is repeated. On the other hand, if it is determined in step 1078 that the timer has reached a predetermined time, the process proceeds to step 1080 and the converter goes to sleep. Therefore, every time an interrupt signal is generated, the converter 175 is activated and the timer is reset to sleep. If the detected pressure on the pen tip exceeds a predetermined threshold (step 1064) or the side switch state changes (step 1072), interrupt

0105FIG. 16 is a flowchart for exemplifying the steps to be performed when the digital data encoded by the frequency shift in the converter 175 is decoded by the sensor control device 152. At step 1020, the pen frequency state is set to "unknown". At step 1022, it is determined whether the pen frequency has been detected. If so, step 1024 determines whether the pen frequency is "unknown". Specifically, in this example, there may be 10 predefined frequency states. If the frequency detected in step 1022 is not in any of the "known" frequency states, it is instructed to proceed to step 1026 and to find out the frequency movement direction (because it is unknown). After that, the process returns to step 1022 to determine whether or not the pen frequency has been detected. If, in step 1024, it is determined that the pen frequency detected in step 1022 is one of the "known" frequency states, the process proceeds to step 1028 to determine whether or not the frequency has changed since the previous detection. Will be done. If not, the process returns to step 1022 to determine if the pen frequency has been detected.

0106If it is determined in step 1028 that the frequency has changed since the previous detection, the process proceeds to step 1030 to determine whether or not it is necessary to check the frequency movement direction. Initially, the direction of frequency transfer is unknown, so this needs to be investigated. Therefore, the process proceeds to step 1032, and it is determined whether or not the currently detected frequency is lower than the previously detected frequency. If so, it proceeds to step 1034 and is instructed that the frequency has changed from "high" to low. On the other hand, if not, the process proceeds to step 1036, which indicates that the frequency has changed from "low to high". From either step 1034 or 1036, return to step 1022 and determine again whether the pen frequency was detected (in this case "yes" from either step 1034 or step 1036). To. If it is determined that the frequency has changed since the last detection (in this case, "yes" from either step 1034 or step 1036), proceed to step 1028, and in step 1030, change the frequency movement direction. It is decided whether or not it needs to be investigated. At this time, the frequency transfer direction is already indicated as either "high to low" (in step 1034) or "low to high" (in step 1036). Therefore, it is not necessary to check the frequency moving direction, and the process proceeds to step 1038, and the currently detected frequency moves from the previously detected frequency in the same direction as the frequency moving direction as already shown in step 1034 or step 1036. It is decided whether or not it was done. If so, the process proceeds to step 1040, where "1" is recorded if the frequency movement direction is "high to low" and "0" is recorded if the frequency movement direction is "low to high".

0107After that, the process proceeds to step 1042, and it is determined whether or not the currently detected frequency is higher than a predetermined threshold value such as 143 KHz in the illustrated embodiment. This threshold is generally predefined near an intermediate value in the defined frequency range (eg, 143 KHz in the range 100 KHz to 250 KHz in the illustrated embodiment). If the currently detected frequency is higher than this defined threshold, step 1044 indicates that the frequency transfer direction is "high to low". On the other hand, if the currently detected frequency is equal to or less than a predetermined threshold value, step 1046 indicates that the frequency moving direction is low to high. Returning to step 1022 from either step 1044 or 1046, it is determined again whether or not the pen frequency has been detected. If not, the process proceeds to step 1048 to determine if a predetermined time has elapsed since the last detection of the frequency. If so, the process proceeds to step 1050 and is instructed to start new data (or new data frame).

0108In some embodiments of the invention, communication using digital coding and frequency hopping is achieved bidirectionally between the transducer 175 and the sensor 150. The digital data is similarly encoded by the sensor 150 and can be transmitted to the converter 175. The type of data digitally encoded by the sensor 150 may include, for example, sensor identification data, receiving channel data (ie, which frequency channel to use), and operating mode of the sensor 150. Yet or additionally, pressure, switch state, pen identification information (ID information) and other digital data are Bluetooth devices conforming to the IEEE 802.11 standard, including Bluetooth (Bluetooth) and ZigBee protocols. Other RF radio technology may be used to transmit between the converter 175 and the sensor 150, such as via Bluetooth.

0109According to one aspect of the invention, there is provided a cordless transducer 175 configured for use with the electrode array 154. The cordless transducer 175 and the electrode array 154 are capacitively coupled. The cordless converter 175 has a pen-shaped housing (330 in FIG. 3 (b)) having a pen tip (179 in FIG. 3 (b)) at its end, and a converter control device 177 arranged in the pen-shaped housing 330. And. The converter control device 177 controls the operation of the cordless converter 175 and includes a pressure sensor 306 that detects the pressure applied to the tip of the pen. The cordless transducer 175 also comprises an antenna 179 coupled to the transducer controller 177 to transmit the pressure sensor data detected by the pressure sensor 306 as digital data to the electrode array. The converter control device 177 realizes a cordless converter by including a power storage device such as a storage battery or a capacitor (314) that supplies power for driving the converter control device 177 and the antenna 179.

0110The cordless transducer 175 described above, together with the appropriate sensor 150, forms a combinatorial touch and transducer input system. In some embodiments, this combinatorial touch and converter input system is properly formed for the cordless converter 175 to charge a capacitor (314 shown in FIG. 4) via the charging input connector 315. It may further be equipped with a docking station (charging device).

0111A further aspect of the invention provides a method of selectively determining the position of a proximity object and the position of a transducer. This method consists of eight steps. First, proximity objects are capacitively detected using the electrode array 154. Second, the position of the proximity object is determined based on the capacitive detection. Third, an electric field is generated using the converter 175. Fourth, digital data is transmitted from the converter 175 in a predetermined format. Fifth, multiple detection signals are induced based on the electric fields at the corresponding electrodes of the electrode array 154. Sixth, the attributes of these multiple detection signals are measured. Seventh, the position of the converter 175 is determined based on the measurement attributes of the plurality of detection signals. Eighth, digital data is received using the electrode array 154.

0112According to one aspect of the invention, the transducer 175 and sensor 150 can communicate asynchronously for each of converter positioning and digital data communication. Specifically, the systems and methods of the invention according to some embodiments rely on determining the amplitude and frequency of the signal induced in the electrodes, and thus are specified between the transducer 175 and the sensor 150. Does not require phase correlation of. This has many potential advantages. For example, it does not require the use of wired or dedicated wireless links for synchronization. A dedicated wireless link for synchronization may require a bulky transmitter over a portion of the sensor 150. In addition, the dedicated wireless link for synchronization can interfere with other devices and, moreover, be interfered with by other devices. Also, the asynchronous design achievable using the present invention facilitates the use of different frequencies between the transducer 175 and the sensor 150. In addition, the adoption of asynchronous communication is resistant to deterioration over time and is easily compatible with various devices.

0113The examples described herein have been presented to allow one of ordinary skill in the art to practice the invention by describing the invention and its special applications. However, one of ordinary skill in the art will recognize that the above description and examples have been presented for illustration and illustration purposes only. The above description is intended to be comprehensive or not intended to limit the invention to anything that does not differ exactly from the disclosure. Many modifications and changes can be made in view of the above teachings without the spirit of the appended claims.

0114100 ... tablet computer, 102 ... display, 104 ... detection surface, 106 ... finger, 108 ... stylus, 150, 150'... sensor, 152 ... control device, 154 Electrode array, 154b , 154b Electrode, 175 Converter, 177 Converter controller, 179 Antenna, 306 Pressure sensor, 308 Power controller, 310 Side switch, 314,906 Capacitor, 315 Charging input connector, 410,412 multiplexer, 427 Adjacent electrode, 600