Position detection method, integrated circuit, and sensor device

Abstract

To improve an S / N ratio of a pen signal received in a sensor controller, without reducing frequency of position detection, and without increasing the circuit scale of the sensor controller.SOLUTION: A position detection method includes steps of: selecting a first predetermined number of linear electrodes; obtaining a first result by supplying a second AC current from one end side to remaining linear electrodes of the first predetermined number of linear electrodes, while supplying a first AC current from the one end side to a second predetermined number of linear electrodes fewer than the first predetermined number; and obtaining a second result by supplying the second AC current from the one end side to the remaining linear electrodes of the first predetermined number of linear electrodes, while supplying the first AC current from the one end side to a second predetermined number of linear electrodes which does not coincide with the second predetermined number of linear electrodes used in obtaining the first result.SELECTED DRAWING: Figure 24

Description

Technical Field

[0001] The present invention relates to a position detection method, an integrated circuit, and a sensor device.

Background Art

[0002] As one of the methods for detecting the position of an electromagnetic induction pen in a panel surface such as a tablet terminal, an electromagnetic induction method (EMR method) is known. A tablet terminal using the EMR method has a pen detection sensor (hereinafter referred to as an "EMR sensor") arranged in 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. Patent Document 1 discloses an example of an EMR sensor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, it is preferable that the S / N ratio of the pen signal received by the sensor controller is as large as possible. Although several methods for improving the S / N ratio can be considered, one of them is a method of configuring the electromagnetic induction pen so that the transmission period of the pen signal becomes longer. When the detection period of the pen signal in the sensor controller becomes N times, the level of the received pen signal becomes N times, while the level of the received noise is N 1 / 2This is because it remains twice as long. However, on the other hand, if the transmission period of the pen signal is simply lengthened, another problem of a decrease in the frequency of position detection occurs. On the contrary, if the sensor controller receives the pen signal in parallel with a plurality of Rx coils, it is possible to lengthen the transmission period of the pen signal without decreasing the frequency of position detection. However, if this is done, then the number of receiving circuits for the parallel reception is required, and the circuit scale of the sensor controller will increase.

[0005] Therefore, one of the objects of the present invention is to provide a position detection method, an integrated circuit, and a sensor device that can improve the S / N ratio of the pen signal received by the sensor controller without reducing the frequency of position detection and without increasing the circuit scale of the sensor controller.

Means for Solving the Problem

[0006] The position detection method according to the present invention includes a step of obtaining a first result by detecting, using a detection coil, an alternating magnetic field generated by an indicator in response to an alternating magnetic field simultaneously transmitted from a plurality of juxtaposed transmission coil conductors, each of the plurality of transmission coil conductors being connected to a drive circuit in a first connection form in a first period and being supplied with an alternating current from the drive circuit; a step of obtaining a second result by detecting, using a detection coil, an alternating magnetic field generated by the indicator in response to an alternating magnetic field simultaneously transmitted from the plurality of transmission coil conductors, each of the plurality of transmission coil conductors being connected to the drive circuit in a second connection form different from the first connection form in a second period different from the first period; and a step of deriving the position of the indicator based on the first result and the second result.

[0007] The integrated circuit according to the present invention is an integrated circuit that is connected to a plurality of parallel transmission coil conductors, a drive circuit, and a detection coil, and derives the position of an indicator. In a first period, each of the plurality of transmission coil conductors is connected to the drive circuit in a first connection form, and a first result is obtained by detecting, using the detection coil, an alternating magnetic field generated by the indicator in response to an alternating magnetic field simultaneously transmitted from the plurality of transmission coil conductors by an alternating current supplied from the drive circuit. In a second period different from the first period, each of the plurality of transmission coil conductors is connected to the drive circuit in a second connection form different from the first connection form, and a second result is obtained by detecting, using the detection coil, an alternating magnetic field generated by the indicator in response to an alternating magnetic field simultaneously transmitted from the plurality of transmission coil conductors by an alternating current supplied from the drive circuit. Based on the first result and the second result, the position of the indicator is derived.

[0008] The sensor device according to the present invention is a sensor device that derives the position of an indicator, and includes a plurality of parallel transmission coil conductors, a drive circuit, a detection coil, and an integrated circuit connected to the plurality of parallel transmission coil conductors, the drive circuit, and the detection coil. The integrated circuit, in a first period, connects each of the plurality of transmission coil conductors to the drive circuit in a first connection form, and obtains a first result by detecting, using the detection coil, an alternating magnetic field generated by the indicator in response to an alternating magnetic field simultaneously transmitted from the plurality of transmission coil conductors by an alternating current supplied from the drive circuit. In a second period different from the first period, each of the plurality of transmission coil conductors is connected to the drive circuit in a second connection form different from the first connection form, and a second result is obtained by detecting, using the detection coil, an alternating magnetic field generated by the indicator in response to an alternating magnetic field simultaneously transmitted from the plurality of transmission coil conductors by an alternating current supplied from the drive circuit. Based on the first result and the second result, the position of the indicator is derived.

Advantages of the Invention

[0009] According to the present invention, an alternating magnetic field can be simultaneously transmitted from a plurality of transmission coil conductors in each of the first period and the second period, and the signals detected by the detection coil can be separated for each transmission coil conductor. Therefore, without reducing the frequency of position detection and without increasing the circuit scale of the sensor controller, it is possible to improve the S / N ratio of the pen signal received in the sensor controller.

Brief Description of the Drawings

[0010]

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Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0012] 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 corresponding to position detection by the EMR method, and is configured to have a resonance circuit including a coil and a capacitor inside.

[0013] The position detection device 3 is a device corresponding to position detection of the electromagnetic induction pen P by the EMR method, and includes a plurality of loop coils LCx (detection coils), a plurality of loop coils LCy (transmission coil conductors), a switch unit 30, a sensor controller 31, and a host processor 32. A typical example of the position detection device 3 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.

[0014] The illustrated x and y directions are both 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 are arranged side by side in the x direction (second direction). On the other hand, the plurality of loop coils LCy are each formed to extend in the x direction and are arranged side by side in the y direction. Each loop coil LCx and each loop coil LCy are both connected to the switch unit 30 at both ends.

[0015] The switch unit 30 is an aggregate of switches configured by a plurality of switches for switching the connection between the plurality of loop coils LCx and the plurality of loop coils LCy 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.

[0016] FIG. 2 is a diagram showing the internal configuration of the switch unit 30. For simplicity, in the figure, only five loop coils LCx and three loop coils LCy (loop coils LCx n-2 ~LCxn+2 and loop coil LCy m ~LCy m+2 ) are illustrated. This also applies to FIGS. 3 to 5 to be described later. As shown in FIG. 2, the switch section 30 includes two types of switches 30a and 30b, a drive circuit 30c, a wiring section 30d, and an operational amplifier 30e.

[0017] The switch 30a is configured to supply an alternating current Tx for generating an alternating magnetic field on the touch surface and a ground potential to the loop coil LCy. It has an output pin provided for each end of the loop coil LCy and two input pins provided for each output pin. An alternating current is supplied from the drive circuit 30c to one of the two input pins, and a ground potential is supplied from the drive circuit 30c to the other. The switch 30a serves to connect each output pin to either one of the corresponding two input pins according to the control of the sensor controller 31.

[0018] The drive circuit 30c is a circuit that generates an alternating current according to the alternating current Tx supplied from the sensor controller 31 and supplies it to each loop coil LCy via the switch 30a. The process of generating an alternating current by the drive circuit 30c according to the alternating current Tx is typically an amplification process of the alternating current Tx. The drive circuit 30c also serves to supply a ground potential to each loop coil LCy via the switch 30a. The drive circuit 30c commonly supplies the generated alternating current to one of the two input pins corresponding to each loop coil LCy in the switch 30a, and commonly supplies the ground potential to the other of the two input pins corresponding to each loop coil LCy in the switch 30a.

[0019] The switch 30b and the wiring section 30d are configured to supply the pen signal received by each loop coil LCx (the signal indicated by the alternating magnetic field generated by the electromagnetic induction pen P in response to the alternating magnetic field generated in the loop coil LCy) to the operational amplifier 30e. The switch 30b 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 30b serves to connect each input pin to one of the corresponding four output pins according to the control of the sensor controller 31.

[0020] The wiring section 30d is configured to have two wirings L1 and L2. Among these, the wiring L1 is grounded. Two output pins for each input pin of the switch 30b are provided corresponding to these two wirings L1 and L2 and are respectively connected to the corresponding wirings.

[0021] The operational amplifier 30e is a circuit that generates the received signal Rx by amplifying the voltage difference between the input terminal and the ground terminal, and together with the sensor controller 31, constitutes a pen signal receiving circuit. The input terminal of the operational amplifier 30e is connected to the wiring L2 of the wiring section 30d, whereby the received signal Rx is an amplified signal of the signal appearing on the wiring L2. The received signal Rx generated by the operational amplifier 30e is supplied to the sensor controller 31. Instead of the operational amplifier 30e, a differential amplifier that generates the received signal Rx by amplifying the voltage difference between the wiring L2 and the wiring L1 may be used.

[0022] Returning to FIG. 1. The sensor controller 31 is an integrated circuit having a function of detecting the position of the electromagnetic induction pen P within the touch surface by the EMR method. The sensor controller 31 is also 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 sensor controller 31 is configured to sequentially supply the detected position and the acquired data to the host processor 32.

[0023] The host processor 32 uses the position and data supplied from the sensor controller 31 to perform processes such as moving the cursor displayed on the display surface and generating stroke data indicating the trajectory of the electromagnetic induction pen P 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.

[0024] Hereinafter, with reference to FIGS. 3 to 5, the position detection process of the electromagnetic induction pen P performed by the sensor controller 31 will be specifically described.

[0025] FIGS. 3 to 5 are diagrams showing the states of the switch unit 30 when the sensor controller 31 detects the position of the electromagnetic induction pen P. The sensor controller 31 controls the switch 30b to connect one of the loop coils LCx (loop coil LCx in FIGS. 3 to 5 n ) to the operational amplifier 30e, and while doing so, selects each set of three adjacent loop coils LCy in order, and each time, controls the switch 30a so that the three loop coils LCy constituting the selected set are connected to the drive circuit 30c in three connection forms with different connection polarities.

[0026] FIGS. 3 to 5 show the connections in the above three connection forms. Specifically, in the example of FIG. 3, when viewed from the drive circuit 30c, the loop coil LCy m is connected in the counterclockwise direction (denoted as "-1" in the figure), the loop coil LCy m+1 is connected in the clockwise direction (denoted as "1" in the figure), and finally the loop coil LCy m+2 is connected in the counterclockwise direction. Also, in the example of FIG. 4, when viewed from the drive circuit 30c, the loop coil LCy m is connected in the clockwise direction, the loop coil LCy m+1 is connected in the counterclockwise direction, and the loop coil LCy m+2is connected in the counterclockwise direction. In the example of FIG. 5, as seen from the drive circuit 30c, the loop coil LCy m is connected in the counterclockwise direction, and the loop coil LCy m+1 is connected in the counterclockwise direction, and the loop coil LCy m+2 is connected in the clockwise direction.

[0027] FIG. 6 is a diagram for explaining the received signal Rx supplied from the operational amplifier 30e to the sensor controller 31 as a result of making the above-described connections. The illustrated pen signal detection periods T1 to T3 (the first to third periods) respectively correspond to the connection states of FIGS. 3 to 5. Note that, actually, the transmission time of the alternating magnetic field is arranged in the first half of each pen signal detection period, but this is omitted in FIG. 6. Also, although the actual received signal Rx attenuates with time, attenuation is not depicted in FIG. 6 for ease of understanding. The same applies to FIGS. 10 and 11 described later.

[0028] Referring to FIG. 6, it can be understood that the alternating magnetic field transmitted during the pen signal detection period T1 has opposite phases in the loop coil LCy m+1 and the loop coil LCy m , LCy m+2 . This is because, as described above, the loop coil LCy m+1 is in the clockwise direction and the loop coil LCy m , LCy m+2 is in the counterclockwise direction. As a result, the levels of the pen signals received by the loop coil LCx m ~LCy m+2 in response to the alternating magnetic fields respectively transmitted from each of them are denoted as levels E n ~E m,n ~E m+2,n . Then, as shown in FIG. 6, the received signal Rx (result value) supplied from the operational amplifier 30e to the sensor controller 31 during the pen signal detection period T1 is -E m,n +E m+1,n -E m+2,n . The same applies to the pen signal detection periods T2 and T3, which are +E m,n -E m+1,n -E m+2,n , -Em,n -E m+1,n +E m+2,n It will be represented as

[0029] The vector d shown in the following formula (1) LC is the received signal Rx received in each of the pen signal detection periods T1 to T3 described in vector form. The vector d LC As shown in the last line of formula (1), 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 the level E m,n ~E m+2,n Note that the matrix F shown in formula (1) is a 3×3 Walsh code.

[0030]

Equation

[0031] The sensor controller 31 performs the operation shown on the left side of the following formula (2) on the vector d LC to separately obtain the levels E m,n ~E m+2,n Note that the matrix F -1 shown in formula (2) is the inverse matrix of matrix F. Therefore, the operation shown on the left side of formula (2) 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 formula (2), 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 formula (2), the levels E m ~LCy m+2 of the pen signal received by the loop coil LCx corresponding to the alternating magnetic fields respectively sent from each of n It becomes possible to separately obtain m,n ~E m+2,n

[0032]

Equation

[0033] The sensor controller 31 executes an operation similar to that of Equation (2) for each set of loop coils LCy, and when an alternating magnetic field is transmitted from each of the plurality of loop coils LCy m the level of the pen signal received by the loop coil LCx is separately acquired. The sensor controller 31 also performs a similar process while changing the loop coil LCx that receives the pen signal, and when an alternating magnetic field is transmitted from each of the plurality of loop coils LCy n the level of the pen signal received by each of the plurality of loop coils LCx is acquired. Then, the sensor controller 31 derives the position of the electromagnetic induction pen P based on the distribution of the levels of the pen signals thus acquired within the touch surface. Specifically, the position corresponding to the apex of the distribution may be derived as the position of the electromagnetic induction pen P. m Figures 7 to 9 are flowcharts showing the overall flow of the position detection of the electromagnetic induction pen P executed by the sensor controller 31 according to the present embodiment. First, referring to Figure 7, the sensor controller 31 before detecting the electromagnetic induction pen P selects one loop coil LCx at the outermost end and connects it to the operational amplifier 30e (step S1), and selects three loop coils LCy from the end and connects them to the drive circuit 30c in the first connection form (for example, the connection form shown in Figure 3) (step S2).

[0034] Subsequently, the sensor controller 31 starts transmitting an alternating magnetic field from the selected group of loop coils LCy (step S3). Specifically, the supply of the alternating current Tx to the drive circuit 30c is started. As a result, an alternating current is generated in each of the three loop coils LCy either clockwise or counterclockwise, and as a result, an alternating magnetic field corresponding to the direction of the alternating current is transmitted from each of the three loop coils LCy. Thereafter, the sensor controller 31 temporarily stores the level of the received signal Rx output from the operational amplifier 30e in response to the alternating magnetic field transmitted in step S3 (step S4).

[0035]

[0036] ​Next, the sensor controller 31 determines whether it has tried the processes of steps S3 to S4 in all connection forms (step S5). Specifically, it determines whether it has tried the processes of steps S3 to S4 in all of the three connection forms shown in FIGS. 3 to 5. In this determination, if the sensor controller 31 determines that it has not tried, it controls the switch 30a to connect the three selected loop coils LCy to the drive circuit 30c in the next connection form (for example, the connection form shown in FIG. 4 is next to the connection form shown in FIG. 3, and the connection form shown in FIG. 5 is next to the connection form shown in FIG. 4), and returns to step S3.

[0037] On the other hand, if the sensor controller 31 determines in step S5 that it has tried, it derives the level of the pen signal for each loop coil LCy based on the levels of the plurality of received signals Rx temporarily stored by trying step S4 a plurality of times (step S7). Specifically, it performs an operation (restoration operation) of multiplying the above-described vector d LC by the inverse matrix F -1 of the matrix F.

[0038] Next, the sensor controller 31 determines whether the selection of all the loop coils LCy has ended (step S8). If it determines that it has not ended, it selects three loop coils LCy adjacent to the three loop coils LCy selected last time (the ones selected in step S2 or step S9), connects them to the drive circuit 30c in the first connection form (for example, the connection form shown in FIG. 3) by controlling the switch 30a, and then returns to step S3. On the other hand, if it determines in step S8 that it has ended, the sensor controller 31 determines whether the selection of all the loop coils LCx has ended (step S10). If it determines that it has not ended, it selects one loop coil LCx adjacent to the one loop coil LCx selected last time (the one selected in step S1 or step S11), connects it to the operational amplifier 30e, and returns to step S3.

[0039] The sensor controller 31 that has determined to end in step S10 determines whether a pen signal has been detected based on the level of the pen signal for each combination of the loop coil LCy and the loop coil LCx obtained by repeating step S7 (step S12 in FIG. 8). In one example, the result of this determination is affirmative if there is a level exceeding a predetermined value, and negative otherwise.

[0040] The sensor controller 31 that has determined that the pen signal has not been detected in step S12 returns to step S1 in FIG. 7 and continues the process. On the other hand, the sensor controller 31 that has determined 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 loop coil LCy and the loop coil LCx derived in step S7 in FIG. 7, and outputs it to the host processor 32 (step S13).

[0041] Next, the sensor controller 31 determines, based on the position derived in step S13 (in the case of a transition from step S27 described later, the position derived in the previous step S27), 3n loop coils LCy (where n is a natural number, typically n = 1. However, 3n is a number smaller than the total number of loop coils LCy) and a predetermined number (a number smaller than the total number of loop coils LCx. Typically 3 or 4) of loop coils LCx as selection targets (step S14).

[0042] Subsequently, the sensor controller 31 selects the outermost loop coil LCx among the selected loop coils LCx and connects it to the operational amplifier 30e (step S15). Then, it selects three loop coils LCy from the ends of the selected loop coils LCy, and by controlling the switch 30a, connects the selected three loop coils LCy to the drive circuit 30c in a first connection form (for example, the connection form shown in FIG. 3) (step S16).

[0043] It moves to FIG. 9, and then the sensor controller 31 performs the same processing as steps S3 to S12 in FIGS. 7 and 8 (steps S17 to S26). However, the processing here is different from the processing of steps S3 to S12 in that in step S4, only the level of the received signal Rx is temporarily stored, while in step S18, a series of digital values (obtained by sampling) that make up the received signal Rx are also stored; in step S8, it is determined whether the selection of all loop coils LCy has ended, while in step S22, it is determined whether the selection of all loop coils LCy determined as the selection target in step S14 has ended; in step S10, it is determined whether the selection of all loop coils LCx has ended, while in step S24, it is determined whether the selection of all loop coils LCx determined as the selection target in step S14 has ended.

[0044] When the sensor controller 31 determines that the pen signal has been detected in step S26, 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 S27). 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 loop coil LCy and the loop coil LCx derived in step S21. Further, the sensor controller 31 acquires the data transmitted by the electromagnetic induction pen P by demodulating a series of digital values stored in step S18 for the combination of the loop coil LCy and the loop coil LCx closest to the derived position. After step S27 ends, the sensor controller 31 returns to step S14 to continue the processing.

[0045] According to the position detection method of 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. Hereinafter, this effect will be described in detail while comparing it with a comparative example that performs the transmission of an alternating magnetic field by a method different from that of the present embodiment.

[0046] FIG. 10 is a diagram for explaining a received signal Rx according to a first comparative example. The sensor controller 31 according to this comparative example transmits an alternating magnetic field only from one loop coil LCy during each pen signal detection period. In this case, since the level of the pen signal received according to the alternating magnetic field transmitted from one loop coil LCy during each pen signal detection period can be obtained, the sensor controller 31 can acquire the level of the pen signal received according to the alternating magnetic field transmitted from each loop coil LCy without performing the above-described operation.

[0047] FIG. 11 is a diagram for explaining a received signal Rx according to a second comparative example. The sensor controller 31 according to this comparative example transmits an alternating magnetic field simultaneously from three adjacent loop coils LCy during 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 LCy to the drive circuit 30c in the same direction (clockwise or counterclockwise). In this case, although the level of the pen signal received according to the alternating magnetic field transmitted from each of the loop coils LCy cannot be separated by the above-described operation, the sensor controller 31 can derive the position of the electromagnetic induction pen P by regarding the received signal Rx obtained through the transmission of the alternating magnetic field from the three loop coils LCy as being obtained according to the transmission of the alternating magnetic field from the loop coil LCy located at the center of the three loop coils LCy.

[0048] FIG. 12 shows that when the electromagnetic induction pen P is m positioned above the loop coil LCy, each loop coil LCy in the vicinity mThis is a diagram showing the result of simulating the level of the pen signal received in response to the alternating magnetic field transmitted from m (when separating and obtaining, the level after separation). In this figure, the results of this embodiment (FIG. 6), the first comparative example (FIG. 10), and the second comparative example (FIG. 11) are shown respectively. As shown in this figure, according to the position detection method of this embodiment, an effect that the reception level of the pen signal becomes significantly higher compared to the first and second comparative examples can be obtained. This is because, according to the position detection method of this embodiment, the pen signal detection period that can be used to obtain the pen signal received in response to the alternating magnetic field transmitted from each loop coil LCy 1 / 2 becomes three times that of the first and second comparative examples. Here, as described above, 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 is N

[0049] times. Therefore, it can be said that according to the position detection method of this embodiment, it is possible to improve the S / N ratio of the pen signal received in the sensor controller 31.

[0050] In addition, according to the position detection method of this embodiment, the pen signals corresponding to the plurality of loop coils LCy can be simultaneously received by one receiving circuit in each of the plurality of pen signal detection periods, and the received signal Rx can be separated into components for each loop coil LCy. Therefore, there is no need to lengthen the transmission period of the pen signal to improve the S / N ratio, and there is no need to add additional receiving circuits to receive the pen signals in parallel with the plurality of loop coils LCx. Therefore, it can be said that according to the position detection method of this embodiment, it is possible to improve the S / N ratio of the pen signal received in the sensor controller 31 without reducing the frequency of position detection and without increasing the circuit scale of the sensor controller 31. 1 / 2 times. The point that the noise level remains N times when the pen signal detection period of the pen signal in the sensor controller 31 becomes N times will be described in detail.

[0051] Let the received signal Rx obtained during the k-th pen signal detection period be X k , and its variance be denoted as V(X k ). Then, by the additivity of variance, for the N received signals X1 to X N obtained during the 1st to N-th pen signal detection periods, the variance V TOTAL of the signal formed by adding them (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 formula (3).

[0052]

Equation

[0053] Focusing only on the noise components 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 formula (4). Here, V and σ are the variance and standard deviation in each pen signal detection period, respectively.

[0054]

Equation

[0055] The amount of noise appearing in the added signal is represented by the standard deviation σ TOTAL of the added signal. From formula (4), since this standard deviation σ TOTAL is represented as in the following formula (5), 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 1 / 2 times.

[0056]

Equation

[0057] As described above, 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.

[0058] In the present embodiment, an example in which the matrix F shown in Equation (1) 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 coil LCy in each pen signal detection period is set so that the matrix F becomes these codes).

[0059] Generally speaking, when a rotating magnetic field is simultaneously transmitted from k loop coils LCy (that is, while the sensor controller 31 connects any one of the loop coils LCx to the operational amplifier 30e under the control of the switch 30b, k adjacent loop coils LCy are set as one set and each set is sequentially selected, and each time, the k loop coils LCy constituting the selected set are connected to the drive circuit 30c in k connection forms with different connection polarities), if the rank of the matrix F (a k×k matrix), which is the coefficient matrix of the simultaneous equations represented by the following Equation (6), is equal to k, the connection form of the loop coil LCy in each pen signal detection period can be determined based on the matrix F. In other words, if the column vectors of the matrix F (a plurality of vectors indicating different connection states of the loop coil LCy) are linearly independent of each other, the connection form of the loop coil LCy in each pen signal detection period can be determined based on the matrix F. This is because in any case, Equation (6) will always have a solution.

[0060]

Equation

[0061] Each element of such a matrix F does not necessarily have to be "-1" or "1". For example, taking the case of k = 2 for explanation, since any of the matrices F shown in the following equations (7) and (8) has a rank equal to 2, it can be used to determine the connection form of the loop coil LCy in each pen signal detection period. When using the matrix F shown in equation (8), the drive circuit 30c supplies an alternating current with the same direction but different levels (specifically, an alternating current with the same direction and twice the level) to the loop coil LCy corresponding to the element "2" compared to the loop coil LCy corresponding to the element "1".

[0062] [Number]

[0063] 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 LC shown in equation (1) has been obtained as an example, an example of a restoration operation using the matrix F itself as a matrix that is not an inverse matrix of the matrix F will be described.

[0064] In this example, first, using the matrix F for restoration and the levels -E m,n +E m+1,n -E m+2,n , +E m,n -E m+1,n -E m+2,n , -E m,n -E m+1,n +E m+2,n of the received signal Rx in the pen signal detection periods T1 to T3, 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 (9) 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 +E m+1,n +E m+2,n and becomes.

[0065]

Number

[0066] Next, as shown in the following formula (10), a column in which the values of all elements are 1 is added to the beginning of the matrix F, and a row with a value of +E m,n +E m+1,n +E m+2,n is added to the beginning of the vector d LC and then the matrix F is multiplied by the vector d LC to obtain a result obtained by linearly amplifying (specifically, quadrupling) the operation result of formula (9).

[0067]

Number

[0068] Thus, when performing a 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 a restoration operation using the inverse matrix F -1 of the matrix F, the levels E m,n ~E m+2,n+1 can be separated and obtained.

[0069] Note that in formula (10), a result obtained by amplifying the operation result of formula (2) by a factor of 4 is obtained. However, the fact that the operation result becomes large in this way leads to an improvement in the accuracy of the subsequent operations, which is preferable. The same can be said for the case of performing a restoration operation using the inverse matrix F -1 of the matrix F. Specific examples will be given and described below.

[0070] When the matrix F is a 4×4 Walsh code, the vector d LC is represented as in the following formula (11). However, the vector e is a vector indicating the level of the pen signal corresponding to each of the four loop coils LCy.

[0071] [Number]

[0072] The inverse matrix F of the matrix F shown in Equation (11) -1 is expressed as in Equation (12).

[0073] [Number]

[0074] Therefore, when performing the restoration operation of the vector e, as shown in Equation (13) below, if the inverse matrix F -1 is multiplied by 4, it is 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 .

[0075] [Number]

[0076] Next, the position detection system 1 according to the second embodiment of the present invention will be described.

[0077] FIG. 13 is a diagram showing the configuration of the position detection system 1 according to the present embodiment. As can be understood by comparing this figure with FIG. 1, the position detection system 1 according to the present embodiment is different from the first embodiment in that two loop coils LCy adjacent in the y direction are arranged overlapping each other. 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. Therefore, the following description will continue focusing on the differences from the position detection system 1 according to the first embodiment.

[0078] FIG. 14 is a diagram showing the internal configuration of the switch unit 30 arranged in the position detection device 3 constituting the position detection system 1 according to the second embodiment of the present invention. In this figure, only five loop coils LCx and seven loop coils LCy (loop coils LCxn-2 ~LCx n+2 and loop coil LCy m-2 ~LCy m+4 ) is illustrated. This also applies to FIGS. 15 to 17 described later. As can be understood by comparing FIG. 14 with FIG. 1, the internal configuration of the switch unit 30 according to the present embodiment is the same as the internal configuration of the switch unit 30 according to the first embodiment, except that two loop coils LCy adjacent in the y direction are arranged overlapping each other.

[0079] FIGS. 15 to 17 are diagrams showing the states of the switch unit 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, similar to the sensor controller 31 according to the first embodiment, while connecting one of the loop coils LCx (loop coil LCx in FIGS. 15 to 17) to the operational amplifier 30e, selects each set of three adjacent loop coils LCy in order as one set, and each time, controls the switch 30a so that the three loop coils LCy constituting the selected set are connected to the drive circuit 30c in three connection forms with different connection polarities. n ) During the connection, a process of controlling the switch 30a is performed so that the three loop coils LCy constituting the selected set are connected to the drive circuit 30c in three connection forms with different connection polarities.

[0080] The specific content of the three connection forms is also the same as that of the first embodiment. However, in the present embodiment, since two loop coils LCy adjacent in the y direction are arranged overlapping each other, the current paths cross between the two adjacent loop coils LCy. However, even with such a crossing, the levels E m,n ~E m+2,n can be separated and acquired by the same restoration operation as in the first embodiment. Therefore, according to the position detection method according to the present embodiment, similar to the first 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.

[0081] Next, the position detection system 1 according to the third embodiment of the present invention will be described.

[0082] FIG. 18 is a diagram showing the configuration of the position detection system 1 according to the present embodiment. The position detection system 1 according to the present embodiment differs from the position detection system 1 according to the second embodiment in that the position detection device 3 also supports the position detection of the finger F by the capacitance method, the position detection device 3 has a plurality of linear electrodes EL instead of a plurality of loop coils LCy, and the internal configuration of the switch unit 30. 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.

[0083] The plurality of linear electrodes EL are each formed to extend in the x direction and are arranged side by side in a row in the y direction. Each linear electrode EL is connected to the switch unit 30 at both ends.

[0084] The switch unit 30 according to the present embodiment is an assembly of switches constituted by a plurality of switches for switching the connection between the plurality of loop coils LCx, the plurality of linear electrodes EL, and the sensor controller 31. As described in the first embodiment, 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.

[0085] FIG. 19 is a diagram showing the internal configuration of the switch unit 30 according to the present embodiment. For simplicity, in this figure, only five loop coils LCx and six linear electrodes EL (loop coils LCx n-2 ~LCx n+2 and linear electrodes EL m ~EL m+5Only is shown. This also applies to FIGS. 20 to 23 described later. As shown in FIG. 19, the switch unit 30 according to the present embodiment includes switches 30f to 30j, a drive circuit 30k, and an operational amplifier 30m in addition to the switch 30b, the wiring part 30d, and the operational amplifier 30e shown in FIG. 14. The switch 30a and the drive circuit 30c shown in FIG. 2 are not included in the switch unit 30 according to the present embodiment.

[0086] The switch 30f 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 an output pin 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 30f serves to connect each input pin to any one of the output pins for each linear electrode EL in accordance with the control of the sensor controller 31.

[0087] The drive circuit 30k is a circuit that generates the alternating currents i A , i B described below 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 30f. The drive circuit 30k 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.

[0088] The alternating current i A is a current generated, for example, by amplifying the alternating current Tx_EMR using a buffer circuit. On the other hand, the alternating current i B is a current generated so as to satisfy the relationship that the time derivatives of each are in opposite phases with respect to the alternating current i A . Expressing this relationship by a mathematical formula results in the following formula (14).

[0089]

Number

[0090] A typical alternating current i that satisfies the relationship of Equation (14) B is represented by the following Equation (15). However, A is an arbitrary constant. When A = 0, the alternating current i B is the alternating current i A becomes the inversion signal. In this case, the alternating current i A and the alternating current i B will have different signs. 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 will be currents with different levels from each other. Note that the inversion signal of the alternating current i A can be generated using, for example, an inverter buffer circuit. FIG. 19 shows an example of using this inverter buffer circuit.

[0091]

Number

[0092] The potential at the other end of each linear electrode EL that receives the supply of the alternating current i A , i B is preferably set to the potential at the midpoint between the potential generated at one end of the linear electrode EL to which the alternating current i A is supplied and the potential generated at one end of the linear electrode EL to which the alternating current i B is supplied. When A = 0, this potential becomes 0 (i.e., the ground potential).

[0093] The switch 30g is configured to supply the 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 one end of the corresponding linear electrode EL in the x direction (longitudinal direction). The switch 30g serves to connect each input pin to the corresponding output pin in response to the control of the sensor controller 31.

[0094] Switch 30j is configured to switch between a state in which it is connected to the potential of the midpoint described above for the other end of the linear electrode EL in the x-direction (longitudinal direction) and a floating state in which it is not connected to anywhere. FIG. 19 shows the case where the potential of the midpoint described above is the ground potential. In this case, the switch 30j is configured to have a set of input pins and ground pins provided for each linear electrode EL as shown in FIG. 19. Hereinafter, the description will continue on the premise that the potential of the midpoint described above is the ground potential.

[0095] Each input pin of the switch 30j 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 30j is connected to a ground terminal to which the ground potential is supplied. The switch 30j is provided because when the sensor controller 31 detects the position of the electromagnetic induction pen P, it is preferable to set the other end of each linear electrode EL in the x-direction to the ground potential as described above, while 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 30j serves to switch the connection state between each input pin and the corresponding ground pin according to the control of the sensor controller 31.

[0096] The switches 30b, 30h, 30i and the wiring portion 30d are configured to supply the pen signal (transmitted by the electromagnetic induction pen P in response to the alternating magnetic field) received by each loop coil LCx to the operational amplifier 30e and to supply the touch detection signal Tx_TP received by each loop coil LCx to the operational amplifier 30m. Among these, the specific configurations of the switch 30b and the wiring portion 30d are the same as those in the first and second embodiments.

[0097] The switch 30h is a switch that connects the wiring L2 to the input terminal of the operational amplifier 30e and the wiring L1 to the ground terminal according to the control of the sensor controller 31. The switch 30i is a switch that connects the wiring L2 to the input terminal of the operational amplifier 30m according to the control of the sensor controller 31. The initial states of the switches 30h and 30i are both off (non-connected states).

[0098] The operational amplifier 30e is the same as the operational amplifier 30e described in the first embodiment. However, in the present embodiment, the signal generated by the operational amplifier 30e is referred to as the received signal Rx_EMR. The operational amplifier 30m is a circuit that generates a capacitance-type received signal Rx_TP by amplifying the voltage difference between the input terminal and the ground terminal, and together with the sensor controller 31, constitutes a receiving circuit for the touch detection signal Tx_TP. The input terminal of the operational amplifier 30m is connected to the wiring L2 of the wiring section 30d via the switch 30i, whereby the received signal Rx_TP is an amplified signal that appears on the wiring L2. A parallel capacitor for removing high-frequency noise is provided in the operational amplifier 30m. The received signal Rx_EMR generated by the operational amplifier 30e and the received signal Rx_TP generated by the operational amplifier 30m are both supplied to the sensor controller 31.

[0099] Returning to FIG. 18. The sensor controller 31 according to the present embodiment is configured to have a function (detecting the position of the electromagnetic induction pen P within the touch surface by the EMR method and obtaining the data transmitted by the electromagnetic induction pen P by demodulating the pen signal transmitted by the electromagnetic induction pen P) described in the first embodiment, in addition to a function of detecting the position of the finger F on the touch surface by the capacitance method. 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 the finger F are executed in a time-division manner. The sensor controller 31 is configured to sequentially supply the detected position and the acquired data to the host processor 32. The processing performed by the host processor 32 that receives this supply is the same as in the first embodiment.

[0100] Hereinafter, with reference to FIGS. 20 to 23, the processing of detecting the positions of the electromagnetic induction pen P and the finger F performed by the sensor controller 31 will be specifically described.

[0101] First, FIG. 20 is a diagram showing the state of the switch unit 30 when the sensor controller 31 detects the position of the finger F according to the present embodiment. As shown in this figure, in this case, the sensor controller 31 controls the switch 30g so that each input pin and the corresponding output pin are connected. As a result, 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 30j 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.

[0102] 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 (16). The matrix A is a square matrix having a plurality of rows corresponding one-to-one to the plurality of linear electrodes EL, and 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 the linear electrodes EL. The specific value of each element is either "1" or "-1". The matrix A is preferably an orthogonal matrix, but it may not be an orthogonal matrix.

[0103]

Equation

[0104] The sensor controller 31 generates the 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".

[0105] 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 30m in order while maintaining the switch 30i in the connected state. Specifically, the switch 30b is controlled so that each loop coil LCx is connected to the wiring L2 at both ends in order. Note that FIG. 20 shows an example where the loop coil LCx n is connected to the wiring L2.

[0106] Here, when the capacitance formed between the m-th linear electrode EL m and the n-th loop coil LCx n is C mn assuming that, 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 when the n-th loop coil LCx n is connected to the operational amplifier 30m, the received signal Rx_TP supplied from the operational amplifier 30m to the sensor controller 31 has the value shown in the following equation (17).

[0107]

Equation

[0108] Therefore, while the supply of the partial touch detection signal Tx_TP corresponding to each column of the matrix A is being executed, the received signal Rx_TP obtained for the n-th loop coil LCx n is represented as a whole by the vector b shown in the following equation (18).

[0109]

Equation

[0110] The sensor controller 31 separates and acquires the capacitance C mn for each linear electrode EL by performing the operation shown on the left side of the following equation (19) on this vector b. However, the matrix A shown in equation (19) -1is the inverse matrix of matrix A. As shown in Equation (19), when matrix A is multiplied by matrix A -1 the result is the identity matrix I. Therefore, by performing this operation, the sensor controller 31 can, as shown on the right side of Equation (19), obtain the capacitance C n between each linear electrode EL m and the intersection point with the n-th loop coil LCx mn separately.

[0111]

Equation

[0112] The sensor controller 31 executes an operation similar to Equation (19) for each loop coil LCx, thereby deriving the capacitance C mn at each intersection point between the linear electrode EL and the 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. Specifically, similar to the position detection of the electromagnetic induction pen P in the EMR method, the position corresponding to the apex of the distribution may be derived as the position of the finger F.

[0113] Next, FIGS. 21 to 23 are diagrams showing the states of the switch unit 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, while connecting the loop coil LCx n to the operational amplifier 30e under the control of the switches 30b, 30h, and 30i, sequentially selects six adjacent linear electrodes EL while shifting them in groups of three, and each time, the six selected linear electrodes EL are connected to the drive circuit 30k in three connection forms, whereby an alternating current i A flows through half of the six linear electrodes EL, and an alternating current i BA process is performed to control switch 30f so that they each occur. Further, the sensor controller 31 controls switch 30j so that each input pin and the corresponding ground pin are connected, thereby grounding the other end of each linear electrode EL in the x direction.

[0114] Figs. 21 to 23 show the supply of alternating current i A , i B in the above three connection forms. Specifically described, in the example of Fig. 21, alternating current i m+1 , EL m+3 , EL m+5 is supplied to linear electrodes EL A respectively. Also, in the example of Fig. 22, alternating current i m , EL m+2 , EL m+4 is supplied to linear electrodes EL B respectively. In the example of Fig. 23, alternating current i m+1 ~EL m+3 is supplied to linear electrodes EL A respectively. In the example of Fig. 23, alternating current i m , EL m+4 , EL m+5 is supplied to linear electrodes EL B respectively. In the example of Fig. 23, alternating current i m+2 ~EL m+4 is supplied to linear electrodes EL A respectively. In the example of Fig. 23, alternating current i m , EL m+1 , EL m+5 is supplied to linear electrodes EL B respectively.

[0115] Figs. 24(a) to (c) are diagrams schematically showing the methods of supplying alternating current in each of Figs. 21 to 23. Also, Figs. 24(d) to (f) are diagrams showing the equivalent circuits when alternating currents i m ~EL m+5 are supplied to six linear electrodes EL A , i B by the methods shown in Figs. 24(a) to (c) respectively. As shown in these figures, linear electrode EL m+k and linear electrode EL m+k+3For (where k is any of 0, 1, 2), when an alternating current with time differentials opposite to each other is passed, the linear electrode EL located therebetween m+k+1 , EL m+k+2 , regardless of the current flowing through, the linear electrode EL m+k and the linear electrode EL m+k+3 can be regarded as forming a loop coil. Hereinafter, this loop coil will be referred to as the "pseudo loop coil PLC" (transmission coil conductor), and in particular, the pseudo loop coil PLC composed of the linear electrodes EL m+k , EL m+k+3 will be referred to as the "pseudo loop coil PLC m+k ". The connection polarity of the pseudo loop coil PLC m+k is such that 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 (denoted as "-" in the figure), and when 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), they are opposite to each other.

[0116] The arrangement and connection polarity of each pseudo loop coil PLC shown in Fig. 24(d) are exactly the same as the arrangement and connection polarity of each loop coil LCy shown in Fig. 15. Similarly, the arrangement and connection polarity of each pseudo loop coil PLC shown in Fig. 24(e) are exactly the same as the arrangement and connection polarity of each loop coil LCy shown in Fig. 16, and the arrangement and connection polarity of each pseudo loop coil PLC shown in Fig. 24(f) are exactly the same as the arrangement and connection polarity of each loop coil LCy shown in Fig. 17. Therefore, according to the position detection system 1 of the present embodiment, similar to the position detection system 1 of the second embodiment, the position of the electromagnetic induction pen P can be detected.

[0117] More specifically, 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 BWhen supplying the loop coil LCx n If the level of the pen signal received at m+k,n is represented as E, when supplying the alternating current shown in Fig. 24(a), the received signal Rx_EMR (result value) supplied from the operational amplifier 30e to the sensor controller 31 is -E m,n +E m+1,n -E m+2,n will be represented as. The same applies when supplying the alternating current shown in Figs. 24(b) and (c), which are E m,n -E m+1,n -E m+2,n , -E m,n -E m+1,n +E m+2,n will be represented as. Representing this in vector form, the vector d shown in the following equation (20) is as follows. This is exactly the same form as the vector d shown in the above equation (1). And this vector d EL is the same as the vector d LC 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 EL ~E LC in the same way as the vector d m,n ~E m+2,n .

[0118]

Equation

[0119] Since the vector d EL is in the same form as the vector d LC , it can be understood that also in this embodiment, the sensor controller 31 multiplies the vector d EL by the inverse matrix F -1 of the matrix F to obtain the levels E of the pen signals received when sending out alternating magnetic fields from each of the pseudo loop coils PLC m ~PLC m+2 respectively m,n , E m+1,n , E m+2,ncan be separated and obtained. And according to the alternating current supply method of the present embodiment, compared with the case of separately sending an alternating magnetic field from each of the three pseudo-loop coil PLCs, since the length of the period during which the alternating magnetic field is sent from each pseudo-loop coil PLC becomes three times, the level of the received pen signal becomes three times, while the level of the received noise remains 1 / 2 three times. Therefore, it can be said that also by the alternating current supply method of the present embodiment, it is possible to improve the S / N ratio of the pen signal received in the sensor controller 31.

[0120] Figs. 25 to 27 are flowcharts showing the overall flow of the position detection of the electromagnetic induction pen P executed by the sensor controller 31 according to the present embodiment. First, referring to Fig. 25, the sensor controller 31 before detecting the electromagnetic induction pen P first selects one loop coil LCx at the outermost end and connects the selected loop coil LCx to the operational amplifier 30e by controlling the switch 30b (step S30). This process includes the process of connecting the operational amplifier 30e to the wiring L2 and grounding the wiring L1 by controlling the switch 30h, and also includes the process of disconnecting the operational amplifier 30m from the wiring L2 by controlling the switch 30i.

[0121] Subsequently, the sensor controller 31 selects six linear electrodes EL from the ends and connects them to the drive circuit 30k in the first connection form (for example, the connection form shown in Fig. 23) by controlling the switch 30f (step S31). This process includes the process of grounding the other ends in the x direction of each linear electrode EL by controlling the switch 30j, and also includes the process of preventing the touch detection signal Tx_TP from being supplied to each linear electrode EL by controlling the switch 30g.

[0122] Next, the sensor controller 31 starts sending an alternating magnetic field from the group of linear electrodes EL being selected (step S32). Specifically, the supply of the alternating current Tx_EMR to the drive circuit 30k is started. As a result, an alternating current i A , i BAny of them occurs, and as a result, the pseudo-loop coil PLC described above is formed, and an alternating magnetic field is transmitted. Then, the sensor controller 31 temporarily stores the level of the received signal Rx_EMR output from the operational amplifier 30e in response to the alternating magnetic field transmitted in step S32 (step S33).

[0123] Next, the sensor controller 31 determines whether or not the processes of steps S32 to S33 have been tried in all connection forms (step S34). Specifically, it determines whether or not the processes of steps S32 to S33 have been tried in all of the three connection forms shown in FIGS. 21 to 23. In this determination, the sensor controller 31 that determines that the trial has not been performed controls the switch 30f to connect the six linear electrodes EL being selected to the drive circuit 30k in the next connection form (for example, the connection form shown in FIG. 22 is the next of the connection form shown in FIG. 21, and the connection form shown in FIG. 23 is the next of the connection form shown in FIG. 22) (step S35), and returns to step S32.

[0124] On the other hand, the sensor controller 31 that determines that the trial has been performed 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 the plurality of trials of step S33 (step S36). Specifically, the above-described vector d EL is multiplied by the inverse matrix F -1 of the matrix F (restoring operation).

[0125] Next, the sensor controller 31 determines whether the selection of all the linear electrodes EL has been completed (step S37). If it is determined that the selection has not been completed, six linear electrodes EL are selected with a shift of three, and after connecting to the drive circuit 30k in the first connection form (for example, the connection form shown in FIG. 21) under the control of the switch 30f (step S38), the process returns to step S32. On the other hand, if it is determined in step S37 that the selection has been completed, the sensor controller 31 determines whether the selection of all the loop coils LCx has been completed (step S39). If it is determined that the selection has not been completed, one loop coil LCx adjacent to the previously selected one loop coil LCx (selected in step S30 or step S40) is selected, and after connecting to the operational amplifier 30e under the control of the switch 30b (step S40), the process returns to step S32.

[0126] The sensor controller 31 that determines in step S39 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 pseudo loop coil PLC and the loop coil LCx obtained by repeating step S36 (step S41 in FIG. 26). In one example, the result of this determination is affirmative when there is a level exceeding a predetermined value, and negative otherwise.

[0127] The sensor controller 31 that determines in step S41 that the pen signal has not been detected returns to step S30 in FIG. 25 to continue the process. 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 pseudo loop coil PLC and the loop coil LCx derived in step S36 in FIG. 25, and outputs it to the host processor 32 (step S42).

[0128] Next, based on the position derived in step S42 (or the position derived in the previous step S56 in the case of the transition from step S56 described later), the sensor controller 31 determines 3 + 3n linear electrodes EL (a set of linear electrodes, where n is a natural number, typically n = 1, provided that 3 + 3n is a number smaller than the total number of linear electrodes EL) and a predetermined number (a number smaller than the total number of loop coils LCx, typically 3 or 4) of loop coils LCx as selection targets (step S43).

[0129] Subsequently, the sensor controller 31 selects the outermost loop coil LCx among the selected loop coils LCx and connects it to the operational amplifier 30e by controlling the switch 30b (step S44). Further, the sensor controller 31 selects 6 linear electrodes EL from the ends among the selected linear electrodes EL and connects the selected 6 linear electrodes EL to the drive circuit 30k in a first connection form (e.g., the connection form shown in FIG. 21) by controlling the switch 30f (step S45).

[0130] Moving on to FIG. 27, next, the sensor controller 31 performs the same processing as steps S32 to S41 in FIGS. 25 and 26 (steps S46 to S55). However, the processing here differs from the processing of steps S32 to S41 in 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 constitute the received signal Rx_EMR are also stored; in step S37, it is determined whether the selection of all the linear electrodes EL has ended, while in step S51, it is determined whether the selection of all the linear electrodes EL determined as selection targets in step S43 has ended; in step S39, it is determined whether the selection of all the loop coils LCx has ended, while in step S53, it is determined whether the selection of all the loop coils LCx determined as selection targets in step S43 has ended.

[0131] 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 the data 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. Further, the sensor controller 31 acquires the data transmitted by the electromagnetic induction pen P by demodulating a 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 ends, the sensor controller 31 returns to step S43 to continue the processing.

[0132] Also, according to the position detection method of 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. Hereinafter, this effect will be described in detail with reference to the results of experiments.

[0133] FIGS. 28(a) to (c) show the received signals Rx_EMR(−E m+1 +E m,n +E m+1,n −E m+2,n +E m,n −E m+1,n −E m+2,n −E m,n −E m+1,n +E m+2,n ) input to the sensor controller 31 when the electromagnetic induction pen P is positioned above the pseudo loop coil PLC in the connection forms of FIGS. 24(a) to (c). FIGS. 28(d) to (f) show the levels E m,n , E m+1,n , E m+2,n of the pen signal obtained by the restoration calculation shown in Equation (20) when the received signals Rx_EMR shown in FIGS. 28(a) to (c) are acquired.

[0134] As can be understood by comparing FIGS. 28(a) to (c) with FIGS. 28(d) to (e), the level of the pen signal after the restoration operation becomes significantly higher than the level of the received signal Rx_EMR. This is because, as also explained in the first embodiment, according to the position detection method of this embodiment, the pen signal detection period becomes three times the normal period. Here, as described above, when the pen signal detection period 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 also by the position detection system 1 according to this embodiment, it is possible to improve the S / N ratio of the pen signal received in the sensor controller 31 without reducing the frequency of position detection and without increasing the circuit scale of the sensor controller 31.

[0135] This effect is similarly achieved even when the electromagnetic induction pen P is tilted. This will be described below.

[0136] First, FIG. 29 is a diagram for explaining the angles θ and φ indicating the tilt of the electromagnetic induction pen P. FIG. 29(a) shows the angle θ. As shown in the figure, the angle θ is the angle formed by the z direction, which is the direction perpendicular to the touch surface, and the pen axis. The angle θ is also called the "tilt angle". FIG. 29(b) shows the angle φ. As shown in the figure, the angle φ is the angle formed by the x direction, which is the extending direction of the loop coil LCy, and the pen axis.

[0137] FIGS. 30 to 33 are diagrams showing the levels of the pen signals obtained in the cases of (θ, φ) = (0, 0), (60, 0), (60, 90), and (60, 180), respectively. The horizontal axis of each figure shows the position in the y direction in millimeters. -5 mm, 0 mm, and +5 mm on the horizontal axis of each figure are the pseudo loop coils PLC m-1 , PLC m , PLC m+1It corresponds to the position. Also, the vertical axes in FIGS. 30 and 31 indicate the level of the pen signal (the level after restoration operation when restoration operation is performed) in arbitrary units (a.u.), and the vertical axis in FIG. 32 indicates the value obtained by normalizing the level of the pen signal with the maximum value being 1 in arbitrary units.

[0138] Graph A m-1 ,A m ,A m+1 respectively represent the levels of the pen signal at each position acquired by the sensor controller 31 according to the present embodiment when the y-direction position of the electromagnetic induction pen P is -5, 0, +5. Also, Graph B m is, as a comparative example of the present embodiment, when an alternating magnetic field is sent out only from one pseudo loop coil PLC m (that is, when an alternating current is supplied only to the linear electrodes EL m , EL m+3 ), it represents the levels of the pen signal at each position acquired by the sensor controller 31.

[0139] First, referring to each of (a) in FIGS. 30 to 33, it is understood that as the maximum value of the level of the pen signal acquired by the sensor controller 31 according to the present embodiment, even when the angles θ and φ are not 0, a value equal to or greater than that of (θ, φ) = (0, 0) can be obtained. The fact that the maximum value of the level of the pen signal when the angle θ = 60° exceeds that when the angle θ = 0° is due to the fact that the larger the angle θ, the smaller the distance between the coil in the electromagnetic induction pen P and the touch surface. Also, referring to each of (b) in FIGS. 30 to 33, it is understood that regarding the ratio between the level of the pen signal acquired by the sensor controller 31 according to the present embodiment and the level of the pen signal acquired by the sensor controller 31 according to the comparative example, even when the angles θ and φ are not 0, a value equal to or greater than that of (θ, φ) = (0, 0) can be obtained. Therefore, according to the position detection method of the present embodiment, it can be said that it is possible to improve the S / N ratio of the pen signal received by the sensor controller 31 regardless of the values of the angles θ and φ.

[0140] Next, referring to (c) in each of FIGS. 30 to 33, it is understood that the distribution of the levels of the pen signals acquired by the sensor controller 31 according to the present embodiment has substantially the same shape as the distribution of the levels of the pen signals acquired by the sensor controller 31 according to the comparative example. Therefore, it can be said that by adopting the position detection method according to the present embodiment, no error will occur in the result of position detection.

[0141] As described above, according to the position detection method according to the present embodiment, even when the electromagnetic induction pen P is tilted, 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.

[0142] Next, the position detection system 1 according to the fourth embodiment of the present invention will be described. The position detection system 1 according to the present embodiment is different from the position detection system 1 according to the third embodiment in terms of the method of selecting the linear electrode EL that generates an alternating current simultaneously. 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 third embodiment. Therefore, hereinafter, the description will continue focusing on the differences from the position detection system 1 according to the third embodiment.

[0143] FIG. 34(a) is a diagram for explaining the method of selecting the linear electrode EL in the position detection system 1 according to the third embodiment, and FIG. 34(b) is a diagram for explaining the method of selecting the linear electrode EL in the position detection system 1 according to the present embodiment. In these figures, one square represents one linear electrode EL, and two linear electrodes EL connected by a thick dashed line with black circles at both ends correspond to one pseudo loop coil PLC. If the distance between the two linear electrodes EL constituting one pseudo loop coil PLC is referred to as the sensor space SP, then in both the third embodiment and the present embodiment, SP = 2. Also, if the distance between adjacent pseudo loop coils PLC is referred to as the minimum pitch P min then in the third embodiment, P min=1. In this embodiment, P min =2. When P min =1, as shown in Fig. 34(a), no linear electrode EL that does not form a pseudo loop coil PLC is arranged between the linear electrodes EL that form the pseudo loop coil PLC, whereas when P min =2, as shown in Fig. 34(b), a linear electrode EL that does not form a pseudo loop coil PLC (for example, in the left diagram of Fig. 34(b), the second linear electrode EL from the top and the third linear electrode EL from the bottom) is arranged between a plurality of linear electrodes EL that form the pseudo loop coil PLC.

[0144] As in the third embodiment, when P min =1 (the minimum value) is adopted, the maximum number of pseudo loop coil PLCs that can be formed simultaneously is three. This is because if an attempt is made to form a fourth one, the same linear electrode EL will be used by two pseudo loop coil PLCs. On the other hand, when P min =2 (the minimum value + 1) is adopted as in the fourth embodiment, there is no limit to the number of pseudo loop coil PLCs that can be formed simultaneously. In this way, when there is no limit to the number of pseudo loop coil PLCs that can be formed simultaneously, it becomes possible to increase the level of the pen signal obtained by the restoration operation. Hereinafter, this point will be described.

[0145] First, in the following description, a method of forming n pseudo loop coil PLCs simultaneously to detect the received signal Rx_EMR will be referred to as "CDM n". "CDM" is an abbreviation for "Code Division Multiplexing", and n is the order of CDM. When using CDM n, an alternating magnetic field is transmitted from n pseudo loop coil PLCs with n types of polarity patterns, and by multiplying the n received results obtained as a result by an n×n matrix, the level for each pseudo loop coil PLC can be restored in the same manner as in the third embodiment.

[0146] Fig. 34(a) shows an example of "CDM3", and Fig. 34(b) shows an example of "CDM7". As described above, when P minIn the case of \(P = 1\), since the maximum number of pseudo-loop coil PLCs that can be formed simultaneously is three, Fig. 34(a) shows the case where the degree \(n\) takes the maximum value. On the other hand, min In the case of \(P = 2\), since there is no limit to the number of pseudo-loop coil PLCs that can be formed simultaneously, depending on the total number of linear electrodes EL, it is possible to use a degree \(n\) higher than the case of \(n = 7\) shown in Fig. 34(b).

[0147] Figs. 35(a), (b), and (c) are diagrams showing the selection method of the linear electrodes EL in CDM1, CDM3, and CDM7, respectively, and Figs. 35(d), (e), and (f) are diagrams showing the levels of the pen signals (the levels after restoration operation when restoration operation is performed) obtained by CDM1, CDM3, and CDM7, respectively. In these diagrams, the pitch of the linear electrodes EL is set to 5 mm, and Figs. 35(e) and (f) show the levels of the pen signals in each linear electrode EL when the electromagnetic induction pen P is located at the center of each pseudo-loop coil PLC.

[0148] Also, Figs. 36(a) and (b) are diagrams showing the levels of the pen signals obtained when using CDM1, CDM3, and CDM7, respectively. The vertical axis in Fig. 36(a) shows the level of the pen signal (the level after restoration operation when restoration operation is performed) in arbitrary units (a.u.), and the vertical axis in Fig. 36(b) shows the value obtained by normalizing the level of the pen signal with the maximum value being 1 in arbitrary units. Further, Fig. 36(c) is a diagram in which the measured values and theoretical values of the peak values of the pen signal levels in CDM1, CDM3, and CDM7 are plotted.

[0149] As understood from the mutual comparison of Figs. 35(d), (e), and (f) and the results of Figs. 36(a) and (c), the higher the degree \(n\) of the CDM, the higher the level of the obtained pen signal. On the other hand, as shown in Fig. 36(b), the shape of the distribution of the pen signal levels is substantially the same in any of CDM1, CDM3, and CDM7. Therefore, as in this embodiment, minBy adopting =2 (minimum value + 1) and performing CDM at an order higher than n = 3, it can be said that while realizing the detection of the position of the electromagnetic induction pen P equivalent to that in the third embodiment, it is possible to increase the level of the pen signal obtained by the restoration calculation.

[0150] Figures 37 to 40 are for P min =2, when receiving the pen signal by CDM3, similar to FIGS. 30 to 33, are diagrams showing the levels of the pen signals in the cases of (θ, φ) = (0, 0), (60, 0), (60, 90), (60, 180). As can be understood by comparing FIGS. 37 to 40 with FIGS. 30 to 33, the distribution and values of the levels of the received pen signals are for P min =2 and for P min =1 are almost the same. Therefore, even when considering the angles θ and φ, it can be said that the position of the electromagnetic induction pen P can be detected in the same manner as the position detection system 1 according to the third embodiment by using the position detection system 1 according to the present embodiment.

[0151] As described above, the preferred embodiments of the present invention have been explained. However, the present invention is not limited to such embodiments at all, and it goes without saying that the present invention can be implemented in various modes without departing from the gist thereof.

[0152] For example, in the above-described third and fourth embodiments, when detecting the position of the electromagnetic induction pen P, the other ends in the x direction of each linear electrode EL are grounded, and a current i A is supplied to one end of one of the two linear electrodes EL constituting the pseudo loop coil PLC, and a current i B is supplied to the other end of the other, respectively, to explain an example of sending an alternating magnetic field from the pseudo loop coil PLC. However, it is also possible to send an alternating magnetic field from the pseudo loop coil PLC by other methods.

[0153] Figures 41(a), (b), and (c) are diagrams showing cases where an alternating magnetic field is sent from a pseudo loop coil PLC in different ways. Also, Figures 41(d), (e), and (f) are diagrams showing the levels of pen signals obtained when an alternating magnetic field is sent from a pseudo loop coil PLC by the methods shown in Figures 41(a), (b), and (c), respectively.

[0154] In Fig. 41(a), similar to the third and fourth embodiments described above, when detecting the position of the electromagnetic induction pen P, the other ends of the respective linear electrodes EL in the x direction are grounded, and a current i A is supplied to one end of one of the two linear electrodes EL constituting the pseudo loop coil PLC, B and a current i A is supplied to the other end of the other. The case of using this method is shown. On the other hand, in Fig. 41(b), when detecting the position of the electromagnetic induction pen P, the other ends of the respective linear electrodes EL in the x direction are connected to each other, and a current i B is supplied to one end of one of the two linear electrodes EL constituting the pseudo loop coil PLC, A and a current i B is supplied to the other end of the other. The case of using this method is shown. Also, in Fig. 41(c), the other ends of the two linear electrodes EL constituting the pseudo loop coil PLC are connected to each other, and a current i

[0155] As can be understood by comparing Figs. 41(d), (e), and (f) with each other, in both CDM1 and CDM3k, the level and distribution of the pen signal are almost the same. Therefore, no matter which method shown in Figs. 41(a), (b), and (c) is used to send an alternating magnetic field from the pseudo loop coil PLC, the position of the electromagnetic induction pen P can be detected in the same way. However, regarding the method shown in Fig. 41(c), a phase shift occurs when the impedance of the linear electrode EL is high, so it may be unsuitable depending on the impedance of the linear electrode EL. In the methods shown in Figs. 41(a) and (b), such a phase shift problem does not occur.

[0156] In addition, in the above-described fourth embodiment, the cases where the degree n of the CDM is 1, 3, and 7 have been described. However, the degree n of the CDM may be 1 or more.

Explanation of Signs

[0157] 1 Position detection system 3 Position detection device 30 Switch unit 30a, 30b, 30f to 30j Switches 30c, 30k Drive circuit 30d Wiring section 30e, 30m Operational amplifier 31 Sensor controller 32 Host processor EL Linear electrode F Finger L1, L2 Wiring LCx, LCy Loop coil P Electromagnetic induction pen PLC Pseudo loop coil Rx, Rx_EMR, Rx_TP Received signal T1 to T3 Pen signal detection period Tx, Tx_EMR Alternating current Tx_TP Signal for touch detection Tx_TP Signal for partial touch detection i A , i B Alternating current

Claims

1. Selecting a first predetermined number of linear electrodes adjacent to each other from among a plurality of linear electrodes extending parallel to each other; In a first period after executing the selecting step, a first alternating current is supplied from one end to a second predetermined number of linear electrodes, which is less than the first predetermined number, among the first predetermined number of linear electrodes, and a second alternating current is supplied from one end to the remaining linear electrodes among the first predetermined number of linear electrodes. As a result of the supply of the first alternating current and the second alternating current, obtaining a first result by detecting, using a detection coil, an alternating magnetic field generated by an indicator in response to the alternating magnetic field generated in the first predetermined number of linear electrodes; In a second period different from the first period after executing the selecting step, a first alternating current is supplied from one end to a second predetermined number of linear electrodes, which is the same as the second predetermined number among the first predetermined number of linear electrodes but does not match the second predetermined number of linear electrodes in the first period, among the first predetermined number of linear electrodes, and a second alternating current is supplied from one end to the remaining linear electrodes among the first predetermined number of linear electrodes. As a result of the supply of the first alternating current and the second alternating current, obtaining a second result by detecting, using a detection coil, an alternating magnetic field generated by an indicator in response to the alternating magnetic field generated in the first predetermined number of linear electrodes; Deriving the position of the indicator based on the first result and the second result; A position detection method comprising the above steps.

2. 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. The position detection method according to Claim 1.

3. In a third period different from both the first period and the second period after performing the step of selection, a first alternating current is supplied from one end side to a second predetermined number of the linear electrodes among the first predetermined number of linear electrodes, the second predetermined number of linear electrodes not matching either the second predetermined number of linear electrodes in the first or the second predetermined number of linear electrodes in the second period, and a second alternating current is supplied from one end side to the remaining linear electrodes among the first predetermined number of linear electrodes, and a third result is obtained by detecting, using a detection coil, an alternating magnetic field generated by an indicator in response to the alternating magnetic field generated in the first predetermined number of linear electrodes as a result of the supply of the first alternating current and the second alternating current. The step of deriving the position of the indicator derives the position of the indicator based on the first result, the second result, and the third result. The position detection method according to claim 1 or 2.

4. The step of deriving the position of the indicator includes a step of multiplying a vector indicating the first result, the second result, and the third result by a matrix indicating the supply method of the first and the alternating current to the first predetermined number of linear electrodes in the first to third periods. The position detection method according to claim 3.

5. The first predetermined number is six. The second predetermined number is three. The position detection method according to claim 4.

6. For each of the plurality of detection coils, the step of obtaining the first result, the step of obtaining the second result, and the step of obtaining the third result are executed. The step of deriving the position of the indicator derives the position of the indicator based on the first result, the second result, and the third result obtained for each of the plurality of detection coils. The position detection method according to claim 3.

7. An integrated circuit connected to a plurality of linear electrodes extending in parallel to each other and detection coils, for deriving the position of an indicator, selecting a first predetermined number of linear electrodes adjacent to each other from among the plurality of linear electrodes. In a first period after selecting the first predetermined number of linear electrodes, a first alternating current is supplied from one end to a second predetermined number of linear electrodes that is less than the first predetermined number among the first predetermined number of linear electrodes, and a second alternating current is supplied from one end to the remaining linear electrodes among the first predetermined number of linear electrodes. As a result of the supply of the first alternating current and the second alternating current, a first result is obtained by detecting, using a detection coil, an alternating magnetic field generated by an indicator in response to the alternating magnetic field generated in the first predetermined number of linear electrodes, In a second period different from the first period after selecting the first predetermined number of linear electrodes, a first alternating current is supplied from one end to a second predetermined number of linear electrodes that is less than the first predetermined number among the first predetermined number of linear electrodes and that does not match the second predetermined number of linear electrodes in the first period among the first predetermined number of linear electrodes, and a second alternating current is supplied from one end to the remaining linear electrodes among the first predetermined number of linear electrodes. As a result of the supply of the first alternating current and the second alternating current, a second result is obtained by detecting, using a detection coil, an alternating magnetic field generated by an indicator in response to the alternating magnetic field generated in the first predetermined number of linear electrodes, Based on the first result and the second result, deriving the position of the indicator, Integrated circuit.

8. A sensor device for deriving the position of an indicator, A plurality of linear electrodes extending parallel to each other, A detection coil, An integrated circuit connected to the plurality of linear electrodes and the detection coil, and comprising: The integrated circuit: Selects a first predetermined number of linear electrodes adjacent to each other from among the plurality of linear electrodes, In a first period after selecting the first predetermined number of linear electrodes, a first alternating current is supplied from one end to a second predetermined number of linear electrodes that is less than the first predetermined number among the first predetermined number of linear electrodes, and a second alternating current is supplied from one end to the remaining linear electrodes among the first predetermined number of linear electrodes. As a result of the supply of the first alternating current and the second alternating current, a first result is obtained by detecting, using a detection coil, an alternating magnetic field generated by an indicator in response to the alternating magnetic field generated in the first predetermined number of linear electrodes, In a second period different from the first period after selecting the first predetermined number of linear electrodes, a first alternating current is supplied from one end side to the second predetermined number of linear electrodes among the first predetermined number of linear electrodes, which do not coincide with the second predetermined number of linear electrodes in the first period, and a second alternating current is supplied from one end side to the remaining linear electrodes among the first predetermined number of linear electrodes. As a result of the supply of the first alternating current and the second alternating current, a second result is obtained by detecting, using a detection coil, an alternating magnetic field generated by an indicator in response to the alternating magnetic field generated in the first predetermined number of linear electrodes. Based on the first result and the second result, the position of the indicator is derived. Sensor device.

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