Sensor device, integrated circuit, and method of detecting indicator

Abstract

To prevent increase in power consumption even while replacing a Tx coil with a wire electrode.SOLUTION: A sensor device for detecting an indicator comprises: wire electrode groups extended and provided in parallel to each other; a detection coil group crossing the wire electrode group; and an integrated circuit connected to the wire electrode group and the detection coil group. The integrated circuit is configured to select a plurality of wire electrodes adjacent to each other from the wire electrode group and supply first AC current to one ends of a prescribed number of wire electrodes in a longitudinal direction of the plurality of selected wire electrodes while supplying second AC current to one ends of the remaining wire electrodes in a longitudinal direction of the plurality of selected wire electrodes. The first AC current and the second AC current are generated so as to satisfy a relation in which time differential of both currents has reverse phase to each other.SELECTED DRAWING: Figure 26

Description

Technical Field

[0001] The present invention relates to a sensor device, an integrated circuit, and a method for detecting an indicator.

Background Art

[0002] As one method for detecting the position of an electromagnetic induction pen within a panel surface of a tablet terminal or the like, an electromagnetic induction method (EMR method) is known. A tablet terminal using the EMR method includes a pen detection sensor (hereinafter referred to as an "EMR sensor") disposed within the panel surface and a sensor controller connected to the EMR sensor. The EMR sensor includes a plurality of Tx coils arranged side by side in the y direction and a plurality of Rx coils arranged side by side in the x direction. The sensor controller sequentially transmits an alternating magnetic field from the plurality of Tx coils and, each time, receives a reflection signal (hereinafter referred to as a "pen signal") transmitted by the electromagnetic induction pen at each Rx coil, thereby detecting the position of the electromagnetic induction pen and receiving data transmitted by the electromagnetic induction pen.

[0003] Patent Document 1 discloses an example of an EMR sensor. In order to suppress an increase in price, the EMR sensor described in the document is configured to use a drive electrode (a linear electrode to which a drive signal for display is supplied) within a display device as a Tx coil and a signal line (a wiring to which an image signal is supplied) within the display device as an Rx coil. Generation of an alternating magnetic field by the drive electrode is executed by selecting two drive electrodes with a selection signal, flowing a current from one end to the other end of one drive electrode, and flowing the same current from the other end to the one end of the other drive electrode. In the same document, the drive electrodes and signal lines within the display device are further used as touch electrodes for detecting a finger by a capacitance method.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in the Tx coil of the EMR sensor, in order to generate a magnetic field of a required magnitude, it is necessary to pass a current with a larger amplitude compared to a driving signal for display or the like. When such a large current is passed through a linear electrode as a substitute for the Tx coil, since the DC resistance of the linear electrode is larger than that of a general Tx coil, the power consumption increases. Therefore, there has been a need for a technology that can prevent an increase in power consumption while substituting the Tx coil with a linear electrode.

[0006] Therefore, one object of the present invention is to provide a sensor device that can prevent an increase in power consumption while substituting the Tx coil with a linear electrode.

[0007] Also, as in the invention described in Patent Document 1, when two linear electrodes are selected by a selection signal and an alternating magnetic field is generated by passing a current from one end to the other end of one linear electrode while passing the same current from the other end to the one end of the other linear electrode, a phase shift occurs between the two linear electrodes, and as a result, noise is superimposed on the magnetic field detected by the Rx coil, so improvement has been required.

[0008] Therefore, another object of the present invention is to provide a sensor device, an integrated circuit, and a method for detecting an indicator that can reduce noise superimposed on the magnetic field detected by the Rx coil when substituting the Tx coil with a linear electrode.

Means for Solving the Problems

[0009] A sensor device according to an aspect of the present invention is a sensor device that detects an indicator, and includes a linear electrode group extending in parallel with each other, a detection coil group intersecting the linear electrode group, and an integrated circuit connected to the linear electrode group and the detection coil group. The integrated circuit sequentially transmits an alternating magnetic field from the linear electrode group, detects an alternating magnetic field generated by the indicator in response to the alternating magnetic field by the detection coil group, determines a linear electrode set formed of a part of the linear electrode group based on the result of the detection, executes a process of transmitting an alternating magnetic field from at least a part of the linear electrode set a plurality of times, derives a two-dimensional position of the indicator using a plurality of result values detected by at least a part of the detection coil group as a result of each execution, and updates the linear electrode set according to the derived two-dimensional position.

[0010] An integrated circuit according to an aspect of the present invention is an integrated circuit that is connected to a linear electrode group extending in parallel with each other and a detection coil group intersecting the linear electrode group and detects an indicator. The integrated circuit sequentially transmits an alternating magnetic field from the linear electrode group, detects an alternating magnetic field generated by the indicator in response to the alternating magnetic field by the detection coil group, determines a linear electrode set formed of a part of the linear electrode group based on the result of the detection, executes a process of transmitting an alternating magnetic field from at least a part of the linear electrode set a plurality of times, derives a two-dimensional position of the indicator using a plurality of result values detected by at least a part of the detection coil group as a result of each execution, and updates the linear electrode set according to the derived two-dimensional position.

[0011] A method according to one aspect of the present invention is a method for detecting an indicator using a linear electrode group extending in parallel with each other and a detection coil group intersecting the linear electrode group, the method comprising: sequentially transmitting an alternating magnetic field from the linear electrode group; detecting, by the detection coil group, an alternating magnetic field generated by the indicator in response to the alternating magnetic field; determining a linear electrode set composed of a part of the linear electrode group based on the result of the detection; executing a process of transmitting an alternating magnetic field from at least a part of the linear electrode set a plurality of times, and deriving a two-dimensional position of the indicator using a plurality of result values detected by at least a part of the detection coil group as a result of each execution; and updating the linear electrode set according to the derived two-dimensional position.

[0012] A sensor device according to another aspect of the present invention is a sensor device for detecting an indicator, comprising: a linear electrode group extending in parallel with each other; a detection coil group intersecting the linear electrode group; and an integrated circuit connected to the linear electrode group and the detection coil group, wherein the integrated circuit is configured to supply a first alternating current to one end in the longitudinal direction of one or more first linear electrodes among the linear electrode group, and to supply a second alternating current to one end in the longitudinal direction of one or more second linear electrodes different from the first linear electrodes among the linear electrode group, and the first alternating current and the second alternating current are generated so as to satisfy a relationship in which time differentials thereof are opposite in phase to each other.

[0013] An integrated circuit according to another aspect of the present invention is an integrated circuit connected to a linear electrode group extending in parallel with each other and a detection coil group intersecting the linear electrode group for detecting an indicator, the integrated circuit supplying a first alternating current to one end in the longitudinal direction of one or more first linear electrodes among the linear electrode group, and supplying a second alternating current to one end in the longitudinal direction of one or more second linear electrodes different from the one or more first linear electrodes among the linear electrode group, and the first alternating current and the second alternating current are generated so as to satisfy a relationship in which time differentials thereof are opposite in phase to each other.

[0014] A method according to another aspect of the present invention is a method for detecting an indicator using a linear electrode group extending in parallel with each other and a detection coil group intersecting the linear electrode group, the method including: generating a first alternating current and a second alternating current that satisfy a relationship in which their respective time differentials are opposite in phase to each other; supplying the first alternating current to one end in the longitudinal direction of one or more first linear electrodes in the linear electrode group, while supplying the second alternating current to the one end in the longitudinal direction of one or more second linear electrodes different from the one or more first linear electrodes in the linear electrode group.

Advantages of the Invention

[0015] According to the sensor device, integrated circuit, and method for detecting an indicator according to one aspect of the present invention, after identifying a linear electrode set, the two-dimensional position of the indicator can be derived by supplying current only to a predetermined number of linear electrodes constituting the linear electrode set. Therefore, while substituting the Tx coil with a linear electrode, it is possible to prevent an increase in power consumption.

[0016] According to the sensor device, integrated circuit, and method for detecting an indicator according to another aspect of the present invention, it is possible to prevent a phase shift from occurring between two linear electrodes. Therefore, when substituting the Tx coil with a linear electrode, it is possible to reduce noise superimposed on the magnetic field detected by the Rx coil.

Brief Description of the Drawings

[0017]

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Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0019] FIG. 1 is a diagram showing the configuration of a position detection system 1 according to a first embodiment of the present invention. As shown in the figure, the position detection system 1 includes an electromagnetic induction pen P and a position detection device 3. Among these, the electromagnetic induction pen P is a pen (indicator) corresponding to position detection by the EMR method, and is configured to have a resonance circuit including a coil and a capacitor inside.

[0020] The position detection device 3 is a device (sensor device) corresponding to position detection of the electromagnetic induction pen P by the EMR method, and includes a plurality of loop coils LCx (detection coil group), a plurality of linear electrodes EL (linear electrode group), a switch unit 30, a sensor controller 31, and a host processor 32. The position detection device 3 according to a typical example is a tablet terminal or a notebook personal computer whose display surface also serves as a touch surface, but the position detection device 3 may be configured by a digitizer or the like that does not have a display surface.

[0021] Both the illustrated x and y directions are directions within the touch surface and are orthogonal to each other. The plurality of loop coils LCx are each formed to extend in the y direction (first direction) and arranged side by side in the x direction (second direction). On the other hand, the plurality of linear electrodes EL are each formed to extend in the x direction and arranged side by side in the y direction. Each loop coil LCx and each linear electrode EL are both connected to the switch unit 30 at both ends.

[0022] The switch unit 30 is an assembly of switches composed of a plurality of switches for switching the connections between the plurality of loop coils LCx and for switching the connections between the plurality of loop coils LCx, the plurality of linear electrodes EL, and the sensor controller 31. The switch unit 30 may be provided on a dedicated circuit board or in an integrated circuit, or may be provided in the same integrated circuit as the sensor controller 31. The switching state of the switch unit 30 is controlled by the sensor controller 31.

[0023] FIG. 2 is a diagram showing the internal configuration of the switch unit 30. For simplicity, in this figure, only five loop coils LCx and five linear electrodes EL (loop coils LCx n-2 ~LCx n+2 , linear electrodes EL m-2 ~EL m+2 ) are shown. This also applies to FIGS. 3 to 6 and FIGS. 18 to 21 described later. As shown in FIG. 2, the switch unit 30 includes five types of switches 30a to 30f, a drive circuit 30g, a wiring section 30h, a differential amplifier 30i, and an operational amplifier 30j.

[0024] The switch 30a is configured to supply an alternating current Tx_EMR for generating an alternating magnetic field on the touch surface to the plurality of linear electrodes EL, and includes four input pins connected to the drive circuit 30g and an output pin provided for each linear electrode EL. Each output pin is connected to one end of the corresponding linear electrode EL in the x direction (longitudinal direction). The switch 30a serves to connect each input pin to one of the output pins in accordance with the control of the sensor controller 31.

[0025] The drive circuit 30g is a circuit that generates alternating currents i A , i B (see FIGS. 4 to 6) in accordance with the alternating current Tx_EMR supplied from the sensor controller 31 and supplies them to the linear electrodes EL via the switch 30a. The drive circuit 30g supplies the alternating current i A (the first alternating current) to two of the four input pins of the switch 30a, and supplies the alternating current iB configured to supply a second alternating current

[0026] alternating current i A is a current generated by amplifying the alternating current Tx_EMR using, for example, a buffer circuit. On the other hand, the alternating current i B is the alternating current i A is generated so as to satisfy the relationship that the time derivatives of each are in opposite phases with each other. Expressing this relationship by a mathematical formula gives the following formula (1). The relationship of formula (1) means that as the increase in the alternating current i A increases, the decrease in the alternating current i B increases, and as the decrease in the alternating current i A increases, the increase in the alternating current i B increases. It can also be said that as the increase in the potential at the other end with respect to one end in the longitudinal direction of each of one or more linear electrodes EL that supply the alternating current i A increases, the increase in the potential at one end with respect to the other end in the longitudinal direction of each of one or more linear electrodes EL that supply the alternating current i B increases.

[0027]

Number

[0028] A typical alternating current i B satisfying the relationship of formula (1) is represented by the following formula (2). However, A is an arbitrary constant. When A = 0, the alternating current i B becomes the inverted signal of the alternating current i A . In this case, the alternating current i A and the alternating current i B will have different signs from each other. On the other hand, when A is greater than the maximum value of the alternating current i A , the alternating current i A and the alternating current i B will have the same sign and different levels from each other. Note that the alternating current i AThe inverted signal can be generated, for example, using an inverter buffer circuit. FIG. 2 shows an example of using this inverter buffer circuit.

[0029]

Number

[0030] Alternating current i A , i B The potential at the other end of each linear electrode EL that receives the supply of, the alternating current i A is the potential generated at one end of the linear electrode EL to which the alternating current i B is supplied, and the potential at the midpoint between the potential generated at one end of the linear electrode EL to which the alternating current i

[0031] Switch 30b is configured to supply a touch detection signal Tx_TP for detecting the position of the finger F to a plurality of linear electrodes EL, and is configured to have a set of input pins and output pins provided for each linear electrode EL. The touch detection signal Tx_TP is supplied from the sensor controller 31 to each input pin. Each output pin is connected to the corresponding linear electrode EL. Switch 30b serves to connect each input pin to the corresponding output pin in accordance with the control of the sensor controller 31.

[0032] Switch 30f is configured to switch between a state in which the other end of the linear electrode EL in the x direction (longitudinal direction) is connected to the above-described midpoint potential and a floating state in which it is not connected to anywhere. FIG. 2 shows the case where the above-described midpoint potential is the ground potential. In this case, switch 30f is configured to have a set of input pins and ground pins provided for each linear electrode EL as shown in FIG. 2. Hereinafter, the description will continue on the premise that the above-described midpoint potential is the ground potential.

[0033] Each input pin of the switch 30f is connected to the other end of the corresponding linear electrode EL in the x direction (longitudinal direction). On the other hand, each ground pin of the switch 30f is connected to a ground terminal to which a ground potential is supplied. The switch 30f is provided because when the sensor controller 31 detects the position of the electromagnetic induction pen P, as described above, it is preferable to set the other end of each linear electrode EL in the x direction to the ground potential. On the other hand, when the sensor controller 31 detects the position of the finger F, it is necessary to set the other end of each linear electrode EL in the x direction to a floating state. The switch 30f serves to switch the connection state between each input pin and the corresponding ground pin according to the control of the sensor controller 31.

[0034] The switches 30c to 30e and the wiring section 30h are configured to supply the pen signal (a signal indicated by the alternating magnetic field generated by the electromagnetic induction pen P in response to the alternating magnetic field generated by the alternating current Tx_EMR received by each loop coil LCx) received by each loop coil LCx to the differential amplifier 30i, and to supply the touch detection signal Tx_TP received by each loop coil LCx to the operational amplifier 30j.

[0035] Specifically, first, the switch 30c is configured to have input pins provided for each end of the loop coil LCx and four output pins provided for each input pin. The switch 30c serves to connect each input pin to any one of the corresponding four output pins according to the control of the sensor controller 31.

[0036] The wiring section 30h is configured to have four wirings L1 to L4. The four output pins for each input pin of the switch 30c are provided corresponding to these four wirings L1 to L4 and are respectively connected to the corresponding wirings.

[0037] Switch 30d is a switch that, according to the control of the sensor controller 31, connects wiring L1 to the non-inverting input terminal of differential amplifier 30i and wiring L2 to the inverting input terminal of differential amplifier 30i, respectively. Switch 30e is a switch that, according to the control of the sensor controller 31, connects wiring L4 to the input terminal of operational amplifier 30j. The initial states of switches 30d and 30e are both off (non-connected state).

[0038] Differential amplifier 30i is a circuit that generates the received signal Rx_EMR by amplifying the voltage difference between the non-inverting input terminal connected to wiring L1 and the inverting input terminal connected to wiring L2, and together with sensor controller 31 constitutes a received circuit for the pen signal. Also, operational amplifier 30j is a circuit that generates the received signal Rx_TP of the capacitance method by amplifying the voltage difference between the input terminal and the ground terminal, and together with sensor controller 31 constitutes a received circuit for the touch detection signal Tx_TP. The input terminal of operational amplifier 30j is connected to wiring L4 of wiring section 30h via switch 30e, whereby the received signal Rx_TP is the amplified signal that appears on wiring L4. A parallel capacitor for removing high-frequency noise is provided in operational amplifier 30j. The received signal Rx_EMR generated by differential amplifier 30i and the received signal Rx_TP generated by operational amplifier 30j are both supplied to sensor controller 31.

[0039] Returning to FIG. 1. Sensor controller 31 is an integrated circuit having a function of detecting the position of electromagnetic induction pen P in the touch surface by the EMR method and a function of detecting the position of finger F on the touch surface by the capacitance method. Regarding the electromagnetic induction pen P, it is further configured to have a function of acquiring the data transmitted by the electromagnetic induction pen P by demodulating the pen signal transmitted by the electromagnetic induction pen P. The detection of the position of the electromagnetic induction pen P and the acquisition of data from the electromagnetic induction pen P and the detection of the position of finger F are executed in a time-division manner. Sensor controller 31 is configured to sequentially supply the detected position and the acquired data to host processor 32.

[0040] Using the position and data supplied from the sensor controller 31, the host processor 32 performs processes such as moving the cursor displayed on the display surface and generating stroke data indicating the trajectory of the electromagnetic induction pen P or finger within the touch surface. Among these, regarding the stroke data, the host processor 32 also performs processes such as rendering and displaying the generated stroke data, generating and recording digital ink including the generated stroke data, and transmitting the generated digital ink to an external device according to a user's instruction.

[0041] Hereinafter, with reference to FIGS. 3 to 6, the process of detecting the positions of the electromagnetic induction pen P and finger F performed by the sensor controller 31 will be specifically described.

[0042] First, FIG. 3 is a diagram showing the state of the switch unit 30 when the sensor controller 31 according to the present embodiment detects the position of the finger F. As shown in the figure, in this case, the sensor controller 31 controls the switch 30b so that each input pin and the corresponding output pin are connected. Thereby, the touch detection signal Tx_TP is supplied from the sensor controller 31 to one end in the x direction of each linear electrode EL. Further, the sensor controller 31 controls the switch 30f so that each input pin is disconnected from the corresponding ground pin, thereby making the other end in the x direction of each linear electrode EL in a floating state.

[0043] The specific content of the touch detection signal Tx_TP generated by the sensor controller 31 can be represented by the matrix A shown in the following equation (3). The matrix A is a square matrix having a plurality of rows corresponding one-to-one to the plurality of linear electrodes EL. The left side of the subscript attached to each element (A 11 etc.) indicates the output order from the sensor controller 31, and the right side indicates the serial number of the linear electrode EL. M is the total number of linear electrodes EL. The specific value of each element is either "1" or "-1". The matrix A is preferably an orthogonal matrix, but it does not have to be an orthogonal matrix.

[0044]

Number

[0045] The sensor controller 31 generates a touch detection signal Tx_TP for each column of the matrix A and supplies it to each linear electrode EL. The touch detection signal Tx_TP according to a typical example is a binary pulse signal that is high when the corresponding element of the matrix A is 1 and low when it is 1. Hereinafter, the touch detection signal Tx_TP corresponding to one column of the matrix A is referred to as a "partial touch detection signal Tx_TP".

[0046] While the sensor controller 31 supplies one partial touch detection signal Tx_TP to each linear electrode EL, it performs a process of connecting each loop coil LCx to the operational amplifier 30j in order while maintaining the switch 30e in the connected state. Specifically, the switch 30c is controlled so that each loop coil LCx is connected to the wiring L4 at both ends in order. Note that FIG. 3 shows an example in which the loop coil LCx n is connected to the wiring L4.

[0047] Here, when the electrostatic capacitance formed between the m-th linear electrode EL m and the n-th loop coil LCx n is C mn and the partial touch detection signal Tx_TP corresponding to the x-th column of the matrix A is supplied to each linear electrode EL and the n-th loop coil LCx n is connected to the operational amplifier 30j, the received signal Rx_TP supplied from the operational amplifier 30j to the sensor controller 31 has a value shown in the following equation (4).

[0048]

Number

[0049] Therefore, while the supply of the partial touch detection signal Tx_TP corresponding to each column of the matrix A is being executed, the n-th loop coil LCx nThe received signal Rx_TP obtained for this will be represented as a whole by the vector b shown in the following equation (5).

[0050] [Number]

[0051] The sensor controller 31 performs the operation shown on the left side of the following equation (6) on this vector b, thereby separating and obtaining the capacitance C for each linear electrode EL mn . However, the matrix A -1 shown in equation (6) is the inverse matrix of matrix A. As shown in equation (6), when matrix A is multiplied by matrix A -1 , it becomes the identity matrix I. Therefore, by performing this operation, the sensor controller 31 can separate and obtain the capacitance C at the intersection of the n-th loop coil LCx n and each linear electrode EL m as shown on the right side of equation (6). mn

[0052] [Number]

[0053] The sensor controller 31 derives the capacitance C mn for each intersection of the linear electrode EL and the loop coil LCx by executing an operation similar to equation (6) for each loop coil LCx. Then, based on the distribution of the derived capacitances C mn within the touch surface, the sensor controller 31 derives the position of the finger F (two-dimensional position). Specifically, the position corresponding to the apex of the distribution may be derived as the position of the finger F.

[0054] Next, FIGS. 4 to 6 are diagrams showing the states of the switch unit 30 when the sensor controller 31 detects the position of the electromagnetic induction pen P. As shown in these figures, the sensor controller 31 sandwiches one linear electrode EL m and two linear electrodes EL adjacent to one side​m-1 , EL m-2 An alternating current i is supplied to the (first linear electrode), and an alternating current i A is supplied to the two linear electrodes EL adjacent to the other side. m+1 , EL m+2 (second linear electrode). The switch 30a is controlled so that this becomes the case. Also, the sensor controller 31 controls the switch 30f so that each input pin and the corresponding ground pin are connected, thereby grounding the other end in the x direction of each linear electrode EL. B By this control, a pseudo coil centered on the linear electrode EL is formed, and an alternating magnetic field is generated on the touch surface (especially above the linear electrode EL

[0055] ). Hereinafter, generating an alternating magnetic field in this manner is referred to as "sending an alternating magnetic field from the linear electrode EL m ". The sensor controller 31 is configured to sequentially send similar alternating magnetic fields from these linear electrodes EL by executing similar processing on the linear electrodes EL except for the four linear electrodes EL located at both ends of all the linear electrodes EL in order as the linear electrode EL m m . m

[0056] Note that the four linear electrodes EL excluded from the execution of the above processing are preferably arranged at positions outside the touch surface so that the position of the electromagnetic induction pen P can be detected over the entire touch surface. Also, in the present embodiment, alternating currents are passed through two linear electrodes EL on each side of the linear electrode EL m that sends the alternating magnetic field, but alternating currents may be passed through a predetermined number of one or more linear electrodes EL each, for example, one on each side or three or more on each side of the linear electrodes EL.

[0057] Here, as can also be understood from the descriptions of FIGS. 4 to 6, the drive circuit 30g is arranged on one end side in the longitudinal direction of each linear electrode EL, and the alternating currents i A , i BAll of them are supplied to one end (the end on the same side) in the x-direction (longitudinal direction) of the linear electrode EL. Hereinafter, the effects achieved by adopting such a configuration will be described in detail with reference to the comparative example as well.

[0058] FIG. 7(a) is a diagram showing a method of supplying an alternating current to the linear electrode EL in the present embodiment, and FIG. 7(b) is a diagram showing a method of supplying an alternating current in the comparative example. First, referring to FIG. 7(a), in the present embodiment, for the linear electrode EL m-1 ,EL m-2 , an alternating current i A is supplied to one end in the longitudinal direction, while for the linear electrode EL m+1 ,EL m+2 , an alternating current i B is supplied to one end in the longitudinal direction. On the other hand, in the comparative example, as shown in FIG. 7(b), for the linear electrode EL m-1 ,EL m-2 , an alternating current i A is supplied to one end in the longitudinal direction, while for the linear electrode EL m+1 ,EL m+2 , an alternating current i A is supplied to the other end in the longitudinal direction. The method of supplying the alternating current shown in the comparative example is described in, for example, Patent Document 1.

[0059] FIG. 8(a) is a diagram showing the results of measuring the current flowing through each linear electrode EL in the probing region PA1 shown in FIG. 7(a), and FIG. 8(b) is a diagram showing the results of measuring the current flowing through each linear electrode EL in the probing region PA2 shown in FIG. 7(b). The horizontal axis in each figure is time, and the vertical axis is the current value. In FIGS. 8(a) and 8(b), the current measured in the linear electrode EL m+1 ,EL m+2 is drawn after being inverted. In addition, FIGS. 8(a) and 8(b) illustrate the case where the parasitic capacitance (hereinafter referred to as "total parasitic capacitance") of the current path for each linear electrode EL is 1800 pF.

[0060] The linear electrode EL mThe most efficient way to send an alternating magnetic field is through the linear electrode EL m-1 , EL m-2 is equal to the amplitude of the current flowing through (amplitude A shown in Fig. 8(b)) and the linear electrode EL m+1 , EL m+2 is equal to the amplitude of the current flowing through (amplitude B shown in Fig. 8(b)), and the phase difference (phase difference θ shown in Fig. 8(b)) between the current flowing through the linear electrode EL m-1 , EL m-2 and the inversion signal of the current flowing through the linear electrode EL m+1 , EL m+2 is 0°. From this point, as can be understood from Fig. 8(a), in this embodiment, A = B and θ = 0°, and it can be said that an ideal state is realized from the perspective of the transmission efficiency of the alternating magnetic field. On the other hand, as shown in Fig. 8(b), in the comparative example, A ≠ B and θ ≠ 0° (specifically, about 32°). Therefore, according to this embodiment, it can be said that the transmission of the alternating magnetic field from the linear electrode EL m can be efficiently performed compared to the comparative example.

[0061] Figs. 9(a) and (b) are diagrams plotting the measurement results of the phase difference θ, amplitude A, and amplitude B in the comparative example for a plurality of cases with different total parasitic capacitances. The horizontal axis in Figs. 9(a) and (b) is the total parasitic capacitance, the vertical axis in Fig. 9(a) is the phase difference θ, and the vertical axis in Fig. 9(b) is the value of amplitude B / amplitude A expressed as a percentage. As can be understood from Figs. 9(a) and (b), in the comparative example, the greater the total parasitic capacitance, the more it deviates from the ideal state. Therefore, when adopting the comparative example, it can be said that it is necessary to devise the current path so that the total parasitic capacitance becomes smaller. In contrast, in this embodiment, since an ideal state as shown in Fig. 8(a) can be obtained regardless of the total parasitic capacitance, there is no particular need to devise the current path so that the total parasitic capacitance becomes smaller. Therefore, according to this embodiment, the effect that the circuit design becomes easier can also be obtained compared to the comparative example.

[0062] Fig. 10(a) is a diagram showing the waveforms of various signals related to this embodiment, and Fig. 10(b) is a diagram showing the supply methods of various signals related to the comparative example. These figures include the linear electrode EL m-1, EL m-2 The waveform of the current flowing through the linear electrode EL m+1 , EL m+2 The waveform of the current flowing through it, the waveform of the voltage (pen signal) generated inside the electromagnetic induction pen P (Pen resonance waveform), and the waveform of the received signal Rx_EMR detected by the loop coil LCx closest to the electromagnetic induction pen P are shown.

[0063] First, referring to FIG. 10(b), while the sensor controller 31 supplies an alternating current i A to the linear electrode EL (the “alternating magnetic field transmission period” shown in the figure), a pen signal is generated inside the electromagnetic induction pen P, and it can be understood that the same waveform as the alternating current i A generated in the linear electrode EL appears in the received signal Rx_EMR. This waveform of the received signal Rx_EMR is formed by the superposition of the voltage signal induced in the loop coil LCx by the pen signal sent from the electromagnetic induction pen P and the voltage signal induced in the loop coil LCx by the alternating magnetic field sent from the linear electrode EL. When the sensor controller 31 finishes supplying the alternating current i A to the linear electrode EL, the component of the voltage signal induced by the alternating magnetic field sent from the linear electrode EL disappears, so only the component of the voltage signal induced by the pen signal remains in the received signal Rx_EMR. Although it is difficult to see due to the scale relationship, the waveform of the received signal Rx_EMR after the supply of the alternating current i A to the linear electrode EL ends is the same as the waveform of the pen signal. Therefore, the sensor controller 31 according to the comparative example sets the period after the “alternating magnetic field transmission period” as the “position derivation and data reception period” for deriving the position of the electromagnetic induction pen P and receiving the data transmitted by the electromagnetic induction pen P, and based on the received signal Rx_EMR obtained within this period, derives the position of the electromagnetic induction pen P and receives the data transmitted by the electromagnetic induction pen P.

[0064] In contrast, in FIG. 10(a), the waveform of the received signal Rx_EMR has the same waveform as the pen signal over the entire period including the alternating magnetic field transmission period. This is because, as shown in FIG. 8(a), the linear electrode ELm-1 , EL m-2 The current flowing through and the linear electrode EL m+1 , EL m+2 Since there is no phase shift between the current flowing through and these cancel each other out, the voltage signal induced in the loop coil LCx by the alternating magnetic field sent from the linear electrode EL m does not overlap with the received signal Rx_EMR. That is, according to the present embodiment, it can be said that noise overlapping the alternating magnetic field detected by the loop coil LCx is reduced. The sensor controller 31 according to the present embodiment takes advantage of this effect and also uses the "alternating magnetic field transmission period" as the "position derivation period" for deriving the position of the electromagnetic induction pen P. During this period, based on the voltage signal appearing in the loop coil LCx, the position of the electromagnetic induction pen P is derived. Therefore, according to the present embodiment, since the period for receiving the pen signal for deriving the position of the electromagnetic induction pen P can be ensured to be longer than in the comparative example, the position of the electromagnetic induction pen P can be derived with higher accuracy than in the comparative example.

[0065] Note that the reason why the sensor controller 31 according to the present embodiment does not receive the data transmitted by the electromagnetic induction pen P during the "alternating magnetic field transmission period" is that the electromagnetic induction pen P cannot transmit data during the "alternating magnetic field transmission period". To explain in detail, the electromagnetic induction pen P is configured to transmit data by changing the resonance frequency of the resonance circuit in the electromagnetic induction pen P according to the content of the data to be transmitted and thereby modulating the frequency of the pen signal. When the alternating magnetic field from the position detection device 3 is present, the frequency of the pen signal is fixed to the frequency of the alternating magnetic field. Therefore, even if the resonance frequency of the resonance circuit is changed in the electromagnetic induction pen P, the change is not reflected in the frequency of the pen signal. Therefore, the electromagnetic induction pen P cannot transmit data during the "alternating magnetic field transmission period".

[0066] Return to FIGS. 4 to 6. The sensor controller 31 is the linear electrode EL mWhile transmitting an alternating magnetic field, while maintaining the switch 30d in the connected state, three adjacent loop coils LCx are regarded as a set, and each set is sequentially selected. Each time, the switch 30c is controlled so that the three loop coils LCx constituting the selected set are connected in series to the differential amplifier 30i in three connection forms with different connection polarities. By this process, the differential amplifier 30i detects a result value indicating the level of the pen signal based on the potential between both ends of the composite coil composed of the three loop coils LCx connected in series, and outputs it to the sensor controller 31 as the received signal Rx_EMR.

[0067] Figures 4 to 6 show the connections in the above three connection forms. Specifically, in the example of Figure 4, when viewed from the non-inverting input terminal of the differential amplifier 30i, the loop coil LCx n-1 is connected counterclockwise (denoted as "-1" in the figure), then the loop coil LCx n is connected clockwise (denoted as "1" in the figure), and finally the loop coil LCx n+1 is connected counterclockwise. Also, in the example of Figure 5, when viewed from the non-inverting input terminal of the differential amplifier 30i, the loop coil LCx n-1 is connected clockwise, then the loop coil LCx n is connected counterclockwise, and finally the loop coil LCx n+1 is connected counterclockwise. In the example of Figure 6, when viewed from the non-inverting input terminal of the differential amplifier 30i, the loop coil LCx n-1 is connected counterclockwise, then the loop coil LCx n is connected counterclockwise, and finally the loop coil LCx n+1 is connected clockwise.

[0068] FIG. 11 is a diagram for explaining a received signal Rx_EMR supplied from a differential amplifier 30i to a sensor controller 31 as a result of making the above-described connection. The illustrated pen signal detection periods T1 to T3 respectively correspond to the connection states in FIGS. 4 to 6. Note that, actually, an alternating magnetic field transmission period (see FIG. 10) is arranged in the first half of each pen signal detection period, but this is omitted in FIG. 11. Also, although the actual received signal Rx_EMR decays with time as shown in FIG. 10, the decay is not depicted in FIG. 11 for ease of understanding. The same applies to FIGS. 12 and 13 described later.

[0069] Referring to FIG. 11, it is understood that the pen signal received during the pen signal detection period T1 has opposite phases between the loop coil LCx n and the loop coil LCx n-1 , LCx n+1 . As described above, this is due to the loop coil LCx n rotating clockwise and the loop coil LCx n-1 , LCx n+1 rotating counterclockwise. As a result, when the sensor controller 31 generates an alternating magnetic field at the linear electrode EL m , if the levels of the pen signals received by the loop coils LCx n-1 to LCx n+1 are respectively denoted as levels E m,n-1 to E m,n+1 , the received signal Rx_EMR (result value) supplied from the differential amplifier 30i to the sensor controller 31 during the pen signal detection period T1 is represented as -E m,n-1 +E m,n -E m,n+1 as shown in FIG. 11. The same applies to the pen signal detection periods T2 and T3, which are respectively represented as +E m,n-1 -E m,n -E m,n+1 , -E m,n-1 -E m,n +E m,n+1 .

[0070] The vector d shown in the following equation (7) seriesrepresents the received signal Rx_EMR received in each of the pen signal detection periods T1 to T3 in vector form. Vector d series As shown in the last line of Equation (7), it can be transformed into the form of the product of a 3×3 matrix F indicating the connection polarity in each pen signal detection period and a vector representing level E m,n-1 ~E m,n+1 The matrix F shown in Equation (7) is a 3×3 Walsh code.

[0071]

Equation

[0072] The sensor controller 31 performs the operation shown on the left side of the following Equation (8) on vector d series to separately obtain levels E m,n-1 ~E m,n+1 However, the matrix F shown in Equation (8) is the inverse matrix of matrix F. Therefore, the operation shown on the left side of Equation (8) is a restoration operation according to the connection polarity of the loop coil LCx in each of the above-described connection forms. As also shown in Equation (8), since multiplying matrix F by matrix F -1 results in the identity matrix I, the sensor controller 31 performs this restoration operation to obtain, as shown on the right side of Equation (8), the levels E of the pen signals received by each of the loop coils LCx -1 ~LCx m when an alternating magnetic field is sent from the m-th linear electrode EL n-1 ~LCx n+1 separately. m,n-1 ~E m,n+1 can be separately obtained.

[0073]

Equation

[0074] The sensor controller 31 executes an operation similar to Equation (8) for each set of loop coils LCx to obtain the m-th linear electrode EL mWhen an alternating magnetic field is transmitted from [the source], the levels of the pen signals received by each of the plurality of loop coils LCx are separately obtained. The sensor controller 31 also performs the same process while changing the linear electrode EL m that transmits the alternating magnetic field, and obtains the levels of the pen signals received by each of the plurality of loop coils LCx when the alternating magnetic field is transmitted from each of the plurality of linear electrodes EL m . Then, based on the distribution of the levels of the pen signals thus obtained within the touch surface, the sensor controller 31 derives the position (two-dimensional position) of the electromagnetic induction pen P. Specifically, the position corresponding to the apex of the distribution may be derived as the position of the electromagnetic induction pen P. Details of the position detection of the electromagnetic induction pen P executed by the sensor controller 31 will be described more specifically later with reference to FIGS. 15 to 17.

[0075] Here, a comparative example in which the pen signal is received by a method different from that of the present embodiment is taken up, and one of the effects of using the present embodiment is described.

[0076] FIG. 12 is a diagram for explaining the received signal Rx_EMR according to the first comparative example. The sensor controller 31 according to this comparative example connects one loop coil LCx to the differential amplifier 30i in each pen signal detection period. In this case, since the level of the pen signal received by one loop coil LCx can be obtained in each pen signal detection period, the sensor controller 31 can obtain the level of the pen signal received by each loop coil LCx without performing the above-described calculation.

[0077] FIG. 13 is a diagram for explaining a received signal Rx_EMR according to a second comparative example. The sensor controller 31 according to this comparative example connects three adjacent loop coils LCx in series to a differential amplifier 30i in each pen signal detection period, similar to the present embodiment. However, the sensor controller 31 according to this comparative example connects all the loop coils LCx in the same direction (clockwise or counterclockwise). In this case, the level of the pen signal received by each loop coil LCx cannot be separated by the above-described operation. However, the sensor controller 31 can derive the position of the electromagnetic induction pen P by regarding the received signal Rx obtained through the three loop coils LCx as the one obtained by the loop coil LCx located at the center of the three loop coils LCx.

[0078] FIG. 14 is a diagram showing the result of simulating the level of the pen signal (the level after separation in the case of separation and acquisition) received by each loop coil LCx in the vicinity when the electromagnetic induction pen P is located on the loop coil LCx. n The figure shows the results of the present embodiment (FIG. 11), the first comparative example (FIG. 12), and the second comparative example (FIG. 13), respectively. As shown in the figure, according to the pen signal reception method of the present embodiment, an effect that the reception level of the pen signal is significantly increased can be obtained compared with the first and second comparative examples. This is because, according to the pen signal reception method of the present embodiment, the pen signal detection period that can be used to obtain the pen signal received by each individual loop coil LCx is three times that of the first and second comparative examples. Here, as will be described later, when the pen signal detection period of the pen signal in the sensor controller 31 becomes N times, the level of the received pen signal becomes N times, while the level of the received noise remains N 1 / 2 times. Therefore, it can be said that according to the pen signal reception method of the present embodiment, it is possible to improve the S / N ratio of the pen signal received by the sensor controller 31.

[0079] In addition, according to the method for receiving a pen signal according to the present embodiment, the pen signals received by the plurality of loop coils LCx are simultaneously received by one receiving circuit in each of the plurality of pen signal detection periods, and the received signal Rx_EMR can be separated into components for each loop coil LCx. Therefore, it is not necessary to lengthen the transmission period of the pen signal to improve the S / N ratio, nor is it necessary to add additional receiving circuits to receive the pen signals in parallel with the plurality of loop coils LCx. Thus, according to the method for receiving a pen signal according to the present embodiment, it can be said that the S / N ratio of the pen signal received by the sensor controller 31 can be improved without reducing the frequency of position detection and without increasing the circuit scale of the sensor controller 31.

[0080] Hereinafter, the point that the noise level remains N times when the pen signal detection period of the pen signal in the sensor controller 31 is increased by N times will be described in detail. 1 / 2 times will be described in detail.

[0081] Let the received signal Rx obtained in the k-th pen signal detection period be X k , and its variance be represented as V(X k ). Then, by the additivity of variance, the variance V N of the signal obtained by adding the N received signals X1 to X TOTAL obtained in the 1st to N-th pen signal detection periods (hereinafter simply referred to as the "added signal") is represented by the sum of the variances of the received signal Rx in each pen signal detection period, as shown in the following equation (9).

[0082]

Equation

[0083] Focusing only on the noise component included in the received signal Rx, since it is considered that the noise has the same value in all pen signal detection periods, the variance V TOTAL of the added signal is further represented as in the following equation (10). Here, V and σ are the variance and standard deviation in each pen signal detection period, respectively.

[0084] [Number]

[0085] The amount of noise appearing in the addition signal is represented by the standard deviation σ of the addition signal. TOTAL From Equation (10), since this standard deviation σ is represented as in the following Equation (11), it is understood that when the pen signal detection period of the pen signal in the sensor controller 31 becomes N times, the noise level remains N times. TOTAL times. 1 / 2

[0086] [Number]

[0087] Next, the position detection of the electromagnetic induction pen P executed by the sensor controller 31 will be described more specifically with reference to the flowchart.

[0088] FIGS. 15 to 17 are flowcharts showing the overall flow of the position detection of the electromagnetic induction pen P executed by the sensor controller 31. First, referring to FIG. 15, the sensor controller 31 before detecting the electromagnetic induction pen P determines each linear electrode EL except for the two linear electrodes EL at both ends as a selection target (step S1), and selects the one at the most end among the selected linear electrodes EL (step S2). Further, the sensor controller 31 selects three loop coils LCx from the ends, and by controlling the switches 30c to 30e, connects the selected three loop coils LCx to the differential amplifier 30i in the first connection form (for example, the connection form shown in FIG. 4) (step S3).

[0089] Subsequently, the sensor controller 31 starts sending an alternating magnetic field from the selected linear electrode EL (step S4). Specifically, by controlling the switch 30a, as shown in FIG. 4, two linear electrodes EL adjacent to one side across the selected linear electrode EL are driven by the alternating current i in the drive circuit 30g. Ais connected to the output terminal (the output terminal of the buffer circuit), and two linear electrodes EL adjacent to the other side with the selected linear electrode EL sandwiched therebetween are driven by an alternating current i within the drive circuit 30g B is connected to the output terminal (the output terminal of the inverting buffer circuit), and the supply of the alternating current Tx_EMR to the drive circuit 30g is started. Then, the sensor controller 31 temporarily stores the level of the received signal Rx_EMR output from the differential amplifier 30i in response to the alternating magnetic field transmitted in step S4 (step S5). Here, the level of the received signal Rx_EMR to be stored may be, for example, the maximum value in the entire position derivation period shown in FIG. 10(a) (including the position derivation period which is the alternating magnetic field transmission period and the position derivation period after the alternating magnetic field transmission period), or may be the maximum value in the position derivation period after the alternating magnetic field transmission period.

[0090] Next, the sensor controller 31 determines whether or not the processes of steps S4 to S5 have been tried in all connection forms (step S6). Specifically, it is determined whether or not the processes of steps S4 to S5 have been tried in all of the three connection forms shown in FIGS. 4 to 6. In this determination, the sensor controller 31 that determines that it has not been tried controls the switches 30c to 30e to connect the three loop coils LCx being selected to the differential amplifier 30i in the next connection form (for example, the connection form shown in FIG. 5 is next to the connection form shown in FIG. 4, and the connection form shown in FIG. 6 is next to the connection form shown in FIG. 5) (step S7), and returns to step S4.

[0091] On the other hand, the sensor controller 31 that determines that it has been tried in step S6 derives the level of the pen signal for each loop coil LCx based on the levels of the plurality of received signals Rx_EMR temporarily stored by trying the process of step S5 a plurality of times (step S8). Specifically, the restoration operation shown in the above-described formula (8) is performed.

[0092] Next, the sensor controller 31 determines whether the selection of all the loop coils LCx has been completed (step S9). If it is determined that the selection has not been completed, the sensor controller 31 selects three loop coils LCx adjacent to the three loop coils LCx selected previously (the ones selected in step S3 or step S10), connects them to the differential amplifier 30i in the first connection form (for example, the connection form shown in FIG. 4) by controlling the switches 30c to 30e (step S10), and then returns to step S4. On the other hand, if it is determined in step S9 that the selection has been completed, the sensor controller 31 determines whether the selection of all the linear electrodes EL determined as the selection targets in step S1 has been completed (step S11). If it is determined that the selection has not been completed, the sensor controller 31 selects a linear electrode EL adjacent to the previously selected linear electrode EL (the one selected in step S2 or step S12) (step S12), and returns to step S4.

[0093] The sensor controller 31 that determines in step S11 that the selection has been completed determines whether a pen signal has been detected based on the level of the pen signal for each combination of the linear electrode EL and the loop coil LCx obtained by repeating step S8 (step S13 in FIG. 16). In one example, the result of this determination is affirmative if there is a level exceeding a predetermined value, and negative otherwise.

[0094] The sensor controller 31 that determines in step S13 that the pen signal has not been detected returns to step S1 in FIG. 15 to continue the processing. On the other hand, the sensor controller 31 that determines that the pen signal has been detected derives the position of the electromagnetic induction pen P based on the level of the pen signal for each combination of the linear electrode EL and the loop coil LCx derived in step S8 in FIG. 15, and outputs it to the host processor 32 (step S14).

[0095] Next, based on the position derived in step S14 (or the position derived in the previous step S28 in the case of a transition from step S28 described later), the sensor controller 31 determines (updates) a predetermined number (a number less than the number of linear electrodes EL determined as selection targets in step S1 of FIG. 15. Typically 3 or 4) of linear electrodes EL (linear electrode sets) and 3n loops (where n is a natural number, typically n = 1. However, 3n is a number smaller than the total number of loop coils LCx) of loop coils LCx as selection targets (step S15).

[0096] Subsequently, the sensor controller 31 selects the outermost one among the linear electrodes EL to be selected (step S16). Then, three loop coils LCx from the end are selected among the loop coils LCx to be selected, and by controlling switches 30c to 30e, the three selected loop coils LCx are connected to the differential amplifier 30i in the first connection form (for example, the connection form shown in FIG. 4) (step S17).

[0097] Moving on to FIG. 17, next, the sensor controller 31 performs the same processing as steps S4 to S13 in FIGS. 15 and 16 (steps S18 to S27). However, the processing here is different from the processing in steps S4 to S14 in that in step S5, only the level of the received signal Rx_EMR is temporarily stored, while in step S19, a series of digital values (obtained by sampling) that make up the received signal Rx_EMR are also stored; in step S9, it is determined whether the selection of all loop coils LCx has been completed, while in step S23, it is determined whether the selection of all loop coils LCx determined as selection targets in step S15 has been completed; in step S11, it is determined whether the selection of all linear electrodes EL determined as selection targets in step S1 has been completed, while in step S25, it is determined whether the selection of all linear electrodes EL determined as selection targets in step S15 has been completed. The series of digital values stored in step S19 only need to be those during the position derivation and data reception period shown in FIG. 10(a).

[0098] When the sensor controller 31 determines that a pen signal has been detected in step S27, it derives the position of the electromagnetic induction pen P, acquires the data transmitted by the electromagnetic induction pen P, and outputs it to the host processor 32 (step S28). Specifically, the sensor controller 31 derives the position of the electromagnetic induction pen P based on the level of the pen signal for each combination of the linear electrode EL and the loop coil LCx derived in step S22. Further, the sensor controller 31 demodulates a series of digital values stored in step S19 for the combination of the linear electrode EL and the loop coil LCx closest to the derived position, thereby acquiring the data transmitted by the electromagnetic induction pen P. After step S28 is completed, the sensor controller 31 returns to step S15 to continue the process.

[0099] By adopting the above-described processing, according to the sensor controller 31 according to the present embodiment, after once specifying the linear electrode set in step S15 of FIG. 16, it is possible to update the two-dimensional position of the electromagnetic induction pen P by sending an alternating magnetic field only from a predetermined number of linear electrodes EL constituting the linear electrode set. Therefore, it is possible to prevent an increase in power consumption while substituting the Tx coil with the linear electrode EL.

[0100] As described above, according to the position detection system 1 according to the present embodiment, after once specifying the linear electrode set, it is possible to update the two-dimensional position of the electromagnetic induction pen P by sending an alternating magnetic field only from a predetermined number of linear electrodes EL constituting the linear electrode set. Therefore, it is possible to prevent an increase in power consumption while substituting the Tx coil with the linear electrode EL.

[0101] Also, according to the position detection system 1 according to the present embodiment, the linear electrode EL m-1 , EL m-2 the current flowing through and the linear electrode EL m+1 , EL m+2Since it is possible to prevent a phase shift from occurring between the current flowing through the linear electrode EL, it is also possible to reduce the noise superimposed on the alternating magnetic field detected by the Rx coil (loop coil LCx) when the Tx coil is replaced by the linear electrode EL.

[0102] Also, according to the position detection system 1 according to the present embodiment, it is possible to improve the S / N ratio of the pen signal received by the sensor controller 31 without reducing the frequency of position detection and without increasing the circuit scale of the sensor controller 31.

[0103] Also, according to the position detection system 1 according to the present embodiment, both an EMR sensor and a touch sensor (a sensor for detecting a touch by a finger F by an electrostatic capacitance method) can be realized by a set of linear electrodes EL arranged side by side in the y direction and a set of loop coils LCx arranged side by side in the x direction. Therefore, it is possible to reduce the weight and cost of the position detection device as compared with the case where the EMR sensor and the touch sensor are provided separately in one position detection device.

[0104] Also, according to the position detection system 1 according to the present embodiment, since the differential amplifier 30i is used to receive the received signal Rx_EMR, it is possible to suppress variations in the level of the pen signal even if the resistance values vary between the loop coils LCx. This is particularly effective when the loop coils LCx are formed of a high-impedance material such as a metal mesh.

[0105] In the present embodiment, an example in which the matrix F shown in Equation (7) is a matrix represented by a 3×3 Walsh code has been described. However, a matrix represented by a code other than the Walsh code, such as an OVSF code, an M-sequence code, or a Baker code, can also be suitably used as the matrix F (that is, the connection form of the loop coils LCx in each pen signal detection period is set so that the matrix F becomes these codes).

[0106] Generally speaking, when k loop coils LCx are connected in series to the differential amplifier 30i at the same time (that is, while the sensor controller 31 is sending an alternating magnetic field from any of the linear electrodes EL, k adjacent loop coils LCx are regarded as a set, and each set is selected in turn. Each time, the k loop coils LCx constituting the selected set are connected in series to the differential amplifier 30i in k connection forms with different connection polarities. When controlling the switch 30c), if the rank of the matrix F (a matrix with k rows and k columns), which is the coefficient matrix of the system of linear equations represented by the following equation (12), is equal to k, based on this matrix F, the connection form of the loop coil LCx in each pen signal detection period can be determined. In other words, if the column vectors of the matrix F are linearly independent of each other, based on this matrix F, the connection form of the loop coil LCx in each pen signal detection period can be determined. This is because in any case, the equation (12) will always have a solution.

[0107] [Number]

[0108] Also, in this embodiment, an example of performing a restoration operation using the inverse matrix F -1 of the matrix F has been described, but it is also possible to perform a restoration operation using a matrix that is not an inverse matrix. Hereinafter, taking the case where the vector d series shown in equation (7) has been obtained as an example, an example of a restoration operation using the matrix F itself as a matrix that is not the inverse matrix of the matrix F will be described.

[0109] In this example, first, the matrix F for restoration and the levels -E m,n-1 +E m,n -E m,n+1 、+E m,n-1 -E m,n -E m,n+1 、-E m,n-1 -E m,n +E m,n+1Using the above, the level of the received signal Rx corresponding to the case where all columns of the matrix F are 1 is derived. Specifically, by solving the system of simultaneous equations shown in the following equation (13) to obtain a, b, and c, and then deriving a + b + c, the level of the received signal Rx corresponding to the case where all columns of the matrix F are 1 can be derived. The level thus derived is +E m,n-1 +E m,n +E m,n+1 It becomes as follows.

[0110]

Number

[0111] Next, as shown in the following equation (14), a column with all element values being 1 is added to the beginning of the matrix F, and a row with the value +E m,n-1 +E m,n +E m,n+1 is added to the beginning of the vector d series , and then the matrix F is multiplied by the vector d series , and as a result, a result obtained by linearly (specifically, four times) amplifying the calculation result of equation (8) is obtained.

[0112]

Number

[0113] In this way, when performing the restoration operation using a matrix that is not the inverse matrix F -1 of the matrix F, although it is necessary to derive the level of the received signal Rx corresponding to the case where all columns of the matrix F are 1, similar to the case of performing the restoration operation using the inverse matrix F -1 of the matrix F, the levels E m,n-1 ~E m,n+1 can be separated and obtained.

[0114] Note that in equation (14), a result obtained by amplifying the calculation result of equation (8) four times is obtained. However, the fact that the calculation result becomes large in this way leads to an improvement in the accuracy of the subsequent calculation, which is preferable. The inverse matrix F -1The same can be said for the case of performing the restoration operation using

[0115] When the matrix F is a 4×4 Walsh code, the vector d series is represented by the following equation (15). Here, the vector e is a vector indicating the level of the pen signal received in each of the four loop coils LCx.

[0116]

Equation

[0117] The inverse matrix F of the matrix F shown in equation (15) -1 is represented by equation (16).

[0118]

Equation

[0119] Therefore, when performing the restoration operation of the vector e, as shown in the following equation (17), if we multiply the inverse matrix F -1 by 4, it becomes possible to obtain a vector having a level four times that of the original vector e while performing the restoration operation by the inverse matrix F -1 .

[0120]

Equation

[0121] Next, the position detection system 1 according to the second embodiment of the present invention will be described.

[0122] FIG. 18 is a diagram showing the internal configuration of the switch unit 30 disposed in the position detection device 3 that constitutes the position detection system 1 according to the present embodiment. The switch unit 30 according to the present embodiment is different from the switch unit 30 according to the first embodiment in that the wiring portion 30h does not have the wirings L1 and L2, and the switch 30c also does not have output pins corresponding to the wirings L1 and L2, and that it has an operational amplifier 30n instead of the differential amplifier 30i. The switch 30d according to the present embodiment serves to connect the wiring L4 to the input terminal of the operational amplifier 30n and the wiring L3 to the ground terminal, respectively, in accordance with the control of the sensor controller 31. Further, the sensor controller 31 according to the present embodiment is different from the sensor controller 31 according to the first embodiment in that, in order to detect the position of the electromagnetic induction pen P, it connects three loop coils LCx to the operational amplifier 30n in parallel instead of in series. In other respects, the position detection system 1 according to the present embodiment is the same as the position detection system 1 according to the first embodiment, and thus the following description will continue focusing on the differences from the position detection system 1 according to the first embodiment.

[0123] FIGS. 19 to 21 are diagrams showing the states of the switch unit 30 when the sensor controller 31 according to the present embodiment performs position detection of the electromagnetic induction pen P. The sensor controller 31 according to the present embodiment, while sending out an alternating magnetic field from the linear electrode EL m selects each set of three adjacent loop coils LCx in order as one set, and each time, controls the switch 30c so that the three loop coils LCx constituting the selected set are connected in parallel to the operational amplifier 30n in three connection forms with different connection polarities. By this process, the operational amplifier 30n detects a result value indicating the level of the pen signal based on the potential of one end of the composite coil composed of the three loop coils LCx connected in parallel (the potential with respect to the ground terminal), and outputs it as the received signal Rx_EMR to the sensor controller 31.

[0124] Figures 19 to 21 show the connections in the above three connection forms. Specifically, in the example of Figure 19, when viewed from the input terminal of the operational amplifier 30n, the loop coils LCx n-1 , LCx n+1 are connected in a counterclockwise direction (denoted as "-1" in the figure), and the loop coil LCx n is connected in a clockwise direction (denoted as "1" in the figure). Also, in the example of Figure 20, when viewed from the input terminal of the operational amplifier 30n, the loop coil LCx n-1 is connected in a clockwise direction, and the loop coils LCx n , LCx n+1 are connected in a counterclockwise direction. In the example of Figure 21, when viewed from the input terminal of the operational amplifier 30n, the loop coils LCx n-1 , LCx n are connected in a counterclockwise direction, and the loop coil LCx n+1 is connected in a clockwise direction.

[0125] As a result of making the above connections, the received signal Rx_EMR supplied from the operational amplifier 30n to the sensor controller 31 will be represented by the vector d parallel shown in the following equation (18). The meaning of the levels E m,n-1 ~E m,n+1 is as described in the first embodiment. As shown in the last line of equation (18), the vector d parallel can also be transformed into the form of the product of a 3×3 matrix F indicating the connection polarity during each pen signal detection period and a vector representing the levels E series , similar to the vector d m,n-1 ~E m,n+1 described in the first embodiment.

[0126]

Equation

[0127] Since it can be understood that the vector d parallel has the same form as the vector d series , in this embodiment as well, the sensor controller 31 multiplies the vector d parallel by the inverse matrix F of the matrix F-1 By multiplying, the loop coil LCx n-1 ~LCx n+1 The level E of the pen signal received in each of m,n-1 ~E m,n+1 can be separated and obtained. Therefore, also by the pen signal reception method according to the present embodiment, it is possible to obtain the same effect as in the first embodiment. Specifically, while substituting the Tx coil with the linear electrode EL, it is possible to prevent an increase in power consumption. Also, when substituting the Tx coil with the linear electrode EL, it is possible to reduce the noise superimposed on the alternating magnetic field detected by the Rx coil (loop coil LCx). Furthermore, it is possible to improve the S / N ratio of the pen signal received by the sensor controller 31 without reducing the frequency of position detection and without increasing the circuit scale of the sensor controller 31. However, in this regard, when a plurality of loop coils LCx are connected in parallel, the inductance becomes smaller compared to the case of connecting them in series. Therefore, in the present embodiment, the level of the pen signal is smaller than in the first embodiment. Thus, it can be said that the effect of improving the S / N ratio of the pen signal is higher in the first embodiment than in the present embodiment.

[0128] Next, the position detection system 1 according to the third embodiment of the present invention will be described.

[0129] FIG. 22 is a diagram showing the internal configuration of the switch unit 30 arranged in the position detection device 3 that constitutes the position detection system 1 according to the present embodiment. For simplicity, in the figure, only 5 loop coils LCx (loop coils LCx n-2 ~LCx n+2 ) and 6 linear electrodes EL (linear electrodes EL m ~EL m+5 ) are shown. This also applies to FIGS. 23 to 25 described later.

[0130] The switch unit 30 according to the present embodiment differs from the switch unit 30 according to the second embodiment in that it has a switch 30k instead of the switch 30a and a drive circuit 30m instead of the drive circuit 30g. Further, the sensor controller 31 according to the present embodiment differs from the sensor controller 31 according to the second embodiment in that, in order to detect the position of the electromagnetic induction pen P, it supplies an alternating current to six linear electrodes EL m ~EL m+5 simultaneously, while connecting only one loop coil LCx to the operational amplifier 30n at the same time. In other respects, the position detection system 1 according to the present embodiment is the same as the position detection system 1 according to the second embodiment. Therefore, hereinafter, the description will continue focusing on the differences from the position detection system 1 according to the second embodiment.

[0131] The switch 30k is configured to supply an alternating current Tx_EMR for generating an alternating magnetic field on the touch surface to a plurality of linear electrodes EL, and includes output pins provided for each linear electrode EL and two input pins provided for each output pin. Each output pin is connected to one end of the corresponding linear electrode EL in the x direction (longitudinal direction). The switch 30k serves to connect each input pin to any one of the output pins for each linear electrode EL according to the control of the sensor controller 31.

[0132] The drive circuit 30m is a circuit that generates the above-described alternating currents i A ,i B in response to the alternating current Tx_EMR supplied from the sensor controller 31 and supplies them to each linear electrode EL via the switch 30k. The drive circuit 30m is configured to supply the alternating current i A to one of the two input pins corresponding to each linear electrode EL and supply the alternating current i B to the other.

[0133] 23 to 25 are diagrams showing the state of the switch section 30 when the sensor controller 31 according to the present embodiment detects the position of the electromagnetic induction pen P. The sensor controller 31 according to the present embodiment controls the loop coils LCx n While the linear electrodes EL are connected to the operational amplifier 30n, the adjacent six linear electrodes EL are selected in sequence, shifting three electrodes at a time. Each time, the selected six linear electrodes EL are connected to the driving circuit 30m in three different connection configurations, and an AC current i is applied to half of the six linear electrodes EL. A The remaining half has AC current i B The switch 30c is controlled so that the following two conditions are satisfied:

[0134] 23 to 25 show the supply of AC current in the above three connection configurations. To be more specific, in the example of FIG. 23, the linear electrode EL m+1 ,EL m+3 ,EL m+5 AC current i A However, the linear electrode EL m ,EL m+2 ,EL m+4 AC current i B In the example of FIG. 24, the linear electrode EL m+1 ~EL m+3 AC current i A However, the linear electrode EL m ,EL m+4 ,EL m+5 AC current i B In the example of FIG. 25, the linear electrode EL m+2 ~EL m+4 AC current i A However, the linear electrode EL m ,EL m+1 ,EL m+5 AC current i B are supplied respectively.

[0135] 26(a) to 26(c) are diagrams each showing a method of supplying an AC current in each of the methods shown in FIG. 23 to FIG. 25. Also, FIG. 26(d) to 26(f) are diagrams each showing a method of supplying an AC current to six linear electrodes ELm ~EL m+5 to which an alternating current i A , i B is supplied. As shown in these figures, when an alternating current whose time derivative is in the opposite phase flows through the linear electrode EL m+k (where k is any of 0, 1, 2) and the linear electrode EL m+k+3 , for the linear electrode EL m+k+1 , EL m+k+2 located therebetween, regardless of the current flowing through it, it can be regarded that a loop coil is formed by the linear electrode EL m+k and the linear electrode EL m+k+3 . Hereinafter, this loop coil is referred to as the "pseudo loop coil PLC", and in particular, the pseudo loop coil PLC m+k , EL m+k+3 constituted by is referred to as the "pseudo loop coil PLC m+k ". The connection polarity of the pseudo loop coil PLC m+k is opposite between the case where an alternating current i m+k is supplied to the linear electrode EL A and an alternating current i m+k+3 is supplied to the linear electrode EL B (denoted as "-" in the figure), and the case where an alternating current i m+k is supplied to the linear electrode EL B and an alternating current i m+k+3 is supplied to the linear electrode EL A (denoted as "+" in the figure).

[0136] When an alternating current i m+k is supplied to the linear electrode EL A and an alternating current i m+k+3 is supplied to the linear electrode EL B , if the level of the pen signal received by the loop coil LCx n is represented by E m+k,n , then when the alternating current is supplied as shown in Fig. 26(a), the received signal Rx_EMR (result value) supplied from the operational amplifier 30n to the sensor controller 31 is -E m,n +E m+1,n -E m+2,nIt will be expressed as follows. The same applies when supplying the alternating current shown in FIGS. 26(b) and (c), and they are respectively E m,n -E m+1,n -E m+2,n , -E m,n -E m+1,n +E m+2,n It will be expressed as follows. When expressed in vector form, it is represented as the vector d shown in the following equation (19). And this vector d tx is represented as follows. And this vector d tx is the same as the above-mentioned vector d series and vector d parallel , and can be transformed into the form of the product of a 3×3 matrix F indicating the connection polarity of the pseudo-loop coil PLC and a vector representing the levels E m,n ~E m+2,n .

[0137]

Equation

[0138] As can be understood from the fact that the vector d tx is in the same form as the vector d series and the vector d parallel , also in this embodiment, the sensor controller 31 multiplies the vector d tx by the inverse matrix F -1 of the matrix F to separate and obtain the levels E m ~PLC m+2 of the pen signals received when alternating magnetic fields are sent from each of the pseudo-loop coils PLC m,n , E m+1,n , E m+2,n . And according to the alternating current supply method according to this embodiment, compared with the case where alternating magnetic fields are sent independently from each of the three pseudo-loop coils PLC, the length of the period during which the alternating magnetic fields are sent from each pseudo-loop coil PLC becomes three times, so the level of the received pen signal becomes three times, while the level of the received noise is 3 1 / 2It remains doubled. Therefore, it can be said that the S / N ratio of the pen signal received by the sensor controller 31 can also be improved by the method for supplying an alternating current according to the present embodiment.

[0139] Figs. 27 to 29 are flowcharts showing the overall flow of position detection of the electromagnetic induction pen P executed by the sensor controller 31 according to the present embodiment. First, referring to Fig. 27, the sensor controller 31 before detecting the electromagnetic induction pen P selects one loop coil LCx at the outermost end and connects the selected loop coil LCx to the operational amplifier 30n by controlling the switch 30b (step S30). This process includes connecting the operational amplifier 30n to the wiring L4 and grounding the wiring L3 by controlling the switch 30d, and also includes disconnecting the operational amplifier 30j from the wiring L4 by controlling the switch 30e.

[0140] Subsequently, the sensor controller 31 selects six linear electrodes EL from the ends and connects them to the drive circuit 30m in the first connection form (for example, the connection form shown in Fig. 23) by controlling the switch 30k (step S31). This process includes grounding the other ends in the x direction of each linear electrode EL by controlling the switch 30f, and also includes preventing the touch detection signal Tx_TP from being supplied to each linear electrode EL by controlling the switch 30b.

[0141] Subsequently, the sensor controller 31 starts sending an alternating magnetic field from the selected group of linear electrodes EL (step S32). Specifically, the supply of the alternating current Tx_EMR to the drive circuit 30m is started. As a result, either i A , i B flows through each of the six linear electrodes EL, and as a result, the above-described pseudo loop coil PLC is formed and an alternating magnetic field is sent out. Thereafter, the sensor controller 31 temporarily stores the level of the received signal Rx_EMR output from the operational amplifier 30n in response to the alternating magnetic field sent out in step S32 (step S33). The specific content of the level stored here may be the same as that stored in step S5 of Fig. 15.

[0142] Next, the sensor controller 31 determines whether or not the processes of steps S32 to S33 have been attempted in all connection forms (step S34). Specifically, it determines whether or not the processes of steps S32 to S33 have been attempted in all of the three connection forms shown in FIGS. 23 to 25. In this determination, the sensor controller 31 that determines that the attempt has not been made controls the switch 30k to connect the six linear electrodes EL being selected to the drive circuit 30m in the next connection form (for example, the connection form shown in FIG. 24 is next to the connection form shown in FIG. 23, and the connection form shown in FIG. 25 is next to the connection form shown in FIG. 24) (step S35), and returns to step S32.

[0143] On the other hand, the sensor controller 31 that determines that the attempt has been made in step S34 derives the level of the pen signal for each pseudo loop coil PLC based on the levels of the plurality of received signals Rx_EMR temporarily stored by attempting step S5 a plurality of times (step S36). Specifically, the above-described vector d tx is multiplied by the inverse matrix F -1 of the matrix F (restoration operation).

[0144] Next, the sensor controller 31 determines whether or not the selection of all the linear electrodes EL has been completed (step S37). If it determines that the selection has not been completed, it selects six linear electrodes EL shifted by three, connects them to the drive circuit 30m in the first connection form (for example, the connection form shown in FIG. 23) by controlling the switch 30k (step S38), and returns to step S32. On the other hand, if it determines that the selection has been completed in step S37, the sensor controller 31 determines whether or not the selection of all the loop coils LCx has been completed (step S39). If it determines that the selection has not been completed, it selects one loop coil LCx adjacent to the one loop coil LCx selected last time (the one selected in step S30 or step S40), connects it to the operational amplifier 30n by controlling the switch 30c (step S40), and returns to step S32.

[0145] The sensor controller 31 that determined that the process ended in step S39 determines whether a pen signal was detected based on the level of the pen signal for each combination of the pseudo loop coil PLC and the loop coil LCx obtained by repeating step S36 (step S41 in FIG. 28). In one example, the result of this determination is affirmative if there is a level exceeding a predetermined value, and negative otherwise.

[0146] The sensor controller 31 that determined that the pen signal was not detected in step S41 returns to step S30 in FIG. 27 and continues the process. On the other hand, the sensor controller 31 that determined that the pen signal was detected derives the position of the electromagnetic induction pen P based on the level of the pen signal for each combination of the pseudo loop coil PLC and the loop coil LCx derived in step S36 in FIG. 27, and outputs it to the host processor 32 (step S42).

[0147] Next, based on the position derived in step S42 (in the case of a transition from step S56 described later, the position derived in the previous step S56), the sensor controller 31 determines 3 + 3n linear electrodes EL (where n is a natural number, typically n = 1. However, 3 + 3n is a number smaller than the total number of linear electrodes EL) and a predetermined number (a number less than the total number of loop coils LCx, typically 3 or 4) of loop coils LCx as selection targets (step S43).

[0148] Subsequently, the sensor controller 31 selects the outermost loop coil LCx among the selected loop coils LCx and connects it to the operational amplifier 30n by controlling the switch 30c (step S44). Also, the sensor controller 31 selects 6 linear electrodes EL from the ends among the selected linear electrodes EL, and by controlling the switch 30k, connects the selected 6 linear electrodes EL to the drive circuit 30m in a first connection form (for example, the connection form shown in FIG. 23) (step S45).

[0149] Move to FIG. 29, and then the sensor controller 31 performs the same processing as in steps S32 to S41 of FIGS. 27 and 28 (steps S46 to S55). However, the processing here is such that in step S33, only the level of the received signal Rx_EMR is temporarily stored, while in step S47, a series of digital values (obtained by sampling) that make up the received signal Rx_EMR are also stored. In step S37, it is determined whether the selection of all the linear electrodes EL has been completed, while in step S51, it is determined whether the selection of all the linear electrodes EL determined as the selection target in step S43 has been completed. In step S39, it is determined whether the selection of all the loop coils LCx has been completed, while in step S53, it is determined whether the selection of all the loop coils LCx determined as the selection target in step S43 has been completed. These points are different from the processing of steps S32 to S41.

[0150] When the sensor controller 31 determines that a pen signal has been detected in step S55, it derives the position of the electromagnetic induction pen P, acquires the data transmitted by the electromagnetic induction pen P, and outputs it to the host processor 32 (step S56). Specifically, the sensor controller 31 derives the position of the electromagnetic induction pen P based on the level of the pen signal for each combination of the pseudo loop coil PLC and the loop coil LCx derived in step S50. Also, the sensor controller 31 acquires the data transmitted by the electromagnetic induction pen P by demodulating the series of digital values stored in step S47 for the combination of the pseudo loop coil PLC and the loop coil LCx closest to the derived position. After step S56 is completed, the sensor controller 31 returns to step S43 to continue the processing.

[0151] By adopting the above-described processing, according to the sensor controller 31 according to the present embodiment, after once identifying the linear electrode set in step S43 of FIG. 28, it is possible to update the two-dimensional position of the electromagnetic induction pen P by sending an alternating magnetic field only from a predetermined number of linear electrodes EL constituting the linear electrode set. Therefore, it is possible to prevent an increase in power consumption while substituting the Tx coil with the linear electrode EL.

[0152] As described above, also by the position detection system 1 according to the present embodiment, after once identifying the linear electrode set, it is possible to update the two-dimensional position of the electromagnetic induction pen P by sending an alternating magnetic field only from a predetermined number of linear electrodes EL constituting the linear electrode set. Therefore, it is possible to prevent an increase in power consumption while substituting the Tx coil with the linear electrode EL.

[0153] Also, by the position detection system 1 according to the present embodiment, the alternating current i A , i B is supplied to one end (the same-side end) in the x direction (longitudinal direction) of each linear electrode EL, so that it is possible to prevent a phase shift from occurring between the currents flowing through the respective linear electrodes EL. Therefore, when substituting the Tx coil with the linear electrode EL, it is also possible to reduce the noise superimposed on the alternating magnetic field detected by the Rx coil (loop coil LCx).

[0154] As described above, the preferred embodiments of the present invention have been described. However, the present invention is not limited to such embodiments, and it goes without saying that the present invention can be implemented in various modes without departing from the gist thereof.

[0155] For example, in the first embodiment, an example of generating the received signal Rx_EMR based on the potential between both ends of a composite coil composed of three loop coils LCx connected in series was described. In the second embodiment, an example of generating the received signal Rx_EMR based on the potential of one end of a composite coil composed of three loop coils LCx connected in parallel (the potential with respect to the ground terminal) was described. However, when connecting the three loop coils LCx in series, it is also possible to generate the received signal Rx_EMR based on the potential of one end of the composite coil composed of the three loop coils LCx (the potential with respect to the ground terminal). Also, when connecting the three loop coils LCx in parallel, it is also possible to generate the received signal Rx_EMR based on the potential between both ends of the composite coil composed of the three loop coils LCx.

[0156] Also, in the first and second embodiments, an example of using three adjacent loop coils LCx as a set to detect the position of the electromagnetic induction pen P was described. However, it is also possible to use two adjacent loop coils LCx as a set, or it is also possible to use four or more adjacent loop coils LCx as a set. Alternatively, it is also possible to use all the loop coils LCx as a set. The matrix F when using n (n≧2) loop coils LCx as a set is an n×n matrix.

[0157] Also, in the first and second embodiments, an example of generating the received signal Rx_EMR while changing the mutual connection form of a plurality of loop coils LCx using the switch 30c was described. However, it is also possible to generate the received signal Rx_EMR while changing the connection between each loop coil LCx and the arithmetic circuit. For example, during the pen signal detection period T1 shown in FIG. 11, the loop coil LCx n-1 , LCx n+1 is connected to the subtraction circuit, and the loop coil LCx n is connected to the addition circuit respectively. During the pen signal detection period T2, the loop coil LCx n , LCx n+1 is connected to the subtraction circuit, and the loop coil LCx n-1 is connected to the addition circuit respectively. During the pen signal detection period T3, the loop coil LCx nTo a subtraction circuit, loop coil LCx n-1 , LCx n+1 may be connected to an addition circuit respectively.

[0158] Also, by applying the technology of the present invention, it may be possible to generate a received signal Rx_EMR according to an arbitrary connection form of the loop coil LCx. For example, the difference E between loop coil LCx1 and loop coil LCx2 m,1 -E m,2 or a signal obtained by subtracting the addition signal of loop coils LCx3 and LCx4 from the addition signal of loop coils LCx1 and LCx2 (E m,1 +E m,2 )-(E m,3 +E m,4 ) may be generated. By doing so, it becomes possible to obtain the level of the pen signal according to an arbitrary connection form of the loop coil LCx.

Explanation of Reference Numerals

[0159] 1 Position detection system 3 Position detection device 30 Switch unit 30a~30f, 30k Switches 30g, 30m Drive circuits 30h Wiring section 30i Differential amplifier 30j, 30n Operational amplifiers 31 Sensor controller 32 Host processor EL Linear electrode F Finger L1~L4 Wiring LCx Loop coil P Electromagnetic induction pen PA1, PA2 Probing areas PLC Pseudo loop coil T1~T3 Pen signal detection periods Tx, Tx_EMR Alternating current Tx_TP Signal for touch detection Rx, Rx_EMR, Rx_TP Received signals

Claims

1. A sensor device for detecting an indicator, comprising: A linear electrode group extending parallel to each other; A detection coil group intersecting the linear electrode group; An integrated circuit connected to the linear electrode group and the detection coil group, The integrated circuit: Selects a plurality of adjacent linear electrodes from the linear electrode group, While supplying a first alternating current to one end in the longitudinal direction of a predetermined number among the selected plurality of linear electrodes, it is configured to supply a second alternating current to the other end in the longitudinal direction of the remaining ones among the selected plurality of linear electrodes, The first alternating current and the second alternating current are generated so as to satisfy the relationship that their respective time differentials are in opposite phases, Sensor device.

2. The integrated circuit supplies the first and second alternating currents to the linear electrode group in a plurality of supply forms in which the combinations of the linear electrodes constituting the predetermined number of linear electrodes are different from each other. The sensor device according to Claim 1.

3. The plurality of linear electrodes are an even number of linear electrodes, The predetermined number is half of the even number of linear electrodes, The sensor device according to Claim 2.

4. The even number is 6, The plurality of supply forms are: A first supply form in which, in order from the linear electrode located on one end side in the arrangement direction of the 6 linear electrodes, a second alternating current, a first alternating current, a second alternating current, a first alternating current, a second alternating current, and a first alternating current are supplied to each of the 6 linear electrodes; A second supply form in which, in order from the linear electrode located on one end side in the arrangement direction of the 6 linear electrodes, a first alternating current, a second alternating current, a second alternating current, a second alternating current, a first alternating current, and a first alternating current are supplied to each of the 6 linear electrodes; A third supply form in which, in order from the linear electrode located on one end side in the arrangement direction of the 6 linear electrodes, a second alternating current, a second alternating current, a first alternating current, a first alternating current, a first alternating current, and a second alternating current are supplied to each of the 6 linear electrodes, The sensor device according to Claim 3.

5. The integrated circuit separates and obtains the level of the pen signal received when an alternating magnetic field is transmitted from each of the plurality of pseudo-loop coils constituted by the plurality of linear electrodes, based on the level of the pen signal received in each of the plurality of supply forms in one detection coil among the detection coil group. The sensor device according to any one of claims 2 to 4.

6. The integrated circuit executes the selection of the plurality of linear electrodes a plurality of times while changing the plurality of linear electrodes to be selected. Each time the plurality of linear electrodes are selected, the level of the pen signal is separated and obtained. The sensor device according to claim 5.

7. An integrated circuit connected to a group of linear electrodes extending parallel to each other and a group of detection coils intersecting the group of linear electrodes, for detecting an indicator, selecting a plurality of adjacent linear electrodes from the group of linear electrodes; configured to supply a first alternating current to one end in the longitudinal direction of a predetermined number among the selected plurality of linear electrodes, while supplying a second alternating current to the other end in the longitudinal direction of the remaining selected plurality of linear electrodes; the first alternating current and the second alternating current are generated so as to satisfy a relationship in which the time differentials thereof are opposite in phase to each other. Integrated circuit.

8. A method for detecting an indicator using a group of linear electrodes extending parallel to each other and a group of detection coils intersecting the group of linear electrodes, selecting a plurality of adjacent linear electrodes from the group of linear electrodes; supplying a first alternating current to one end in the longitudinal direction of a predetermined number among the selected plurality of linear electrodes, while supplying a second alternating current to the other end in the longitudinal direction of the remaining selected plurality of linear electrodes, the method including: the first alternating current and the second alternating current are generated so as to satisfy a relationship in which the time differentials thereof are opposite in phase to each other. Method.

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