Position detection method, integrated circuit, and sensor device

Abstract

The purpose of the present invention is to improve the S / N ratio of a pen signal received by a sensor controller without reducing the frequency of position detection and without increasing the circuit scale of the sensor controller. The position detection method comprises the following steps: during a period T1, each loop coil LCy is connected with a drive circuit in a first connection mode, and an alternating magnetic field generated by an indicator according to an alternating magnetic field sent from each loop coil LCy simultaneously by an alternating current supplied from the drive circuit is detected; during a period T2, each loop coil LCy is connected to the drive circuit in a second connection mode different from the first connection mode, and an alternating magnetic field generated by an indicator according to an alternating magnetic field simultaneously sent from each loop coil LCy by an alternating current supplied from the drive circuit is detected; and deriving the position of the indicator on the basis of the detection results in each step.

Description

Technical Field

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

[0002] The electromagnetic induction method (EMR method) is known as one of the methods for detecting the position of an electromagnetic induction pen within the panel surface of a tablet terminal or the like. Tablet terminals using the EMR method include a pen detection sensor (hereinafter referred to as the "EMR sensor") disposed within the panel surface and a sensor controller connected to the EMR sensor. The EMR sensor is constructed by including multiple Tx coils arranged along the y-direction and multiple Rx coils arranged along the x-direction. The sensor controller sequentially transmits an alternating magnetic field from the multiple Tx coils, and each Rx coil receives a reflected signal (hereinafter referred to as the "pen signal") emitted by the electromagnetic induction pen, 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.

[0003] [Prior art literature]

[0004] [Patent Document]

[0005] [Patent Document 1] Japanese Patent No. 6698386. Summary of the Invention

[0006] [Problems to be Solved by the Invention]

[0007] Furthermore, it is preferable that the S / N ratio of the pen signal received by the sensor controller be as large as possible. Several methods are conceivable for improving the S / N ratio, one of which is to construct the electromagnetic induction pen so that the transmission period of the pen signal is extended. This is because when the detection period of the pen signal in the sensor controller is increased by N times, the level of the received pen signal is increased by N times, while the level of the received noise remains at N times. 1 / 2 times. However, simply extending the pen signal transmission period leads to a reduction in the frequency of position detection. By contrast, if the sensor controller receives pen signals in parallel using multiple Rx coils, the pen signal transmission period can be extended without reducing the frequency of position detection. However, this requires a number of receiving circuits sufficient for parallel reception, increasing the circuit size of the sensor controller.

[0008] 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 a pen signal received in a sensor controller without reducing the frequency of position detection and without increasing the circuit scale of the sensor controller.

[0009] [Means for solving the problem]

[0010] The position detection method of the present invention includes the following steps: in a first period, a plurality of transmitting coil conductors arranged in parallel are respectively connected to a driving circuit in a first connection manner, and a detection coil is used to detect an alternating magnetic field generated by an indicator according to the alternating magnetic field simultaneously transmitted from the plurality of transmitting coil conductors by the alternating current supplied from the driving circuit, thereby obtaining a first result; in a second period different from the first period, the plurality of transmitting coil conductors are respectively connected to the driving circuit in a second connection manner different from the first connection manner, and a detection coil is used to detect an alternating magnetic field generated by the indicator according to the alternating magnetic field simultaneously transmitted from the plurality of transmitting coil conductors by the alternating current supplied from the driving circuit, thereby obtaining a second result; based on the first result and the second result, the position of the indicator is derived.

[0011] The integrated circuit of the present invention is connected to a plurality of transmitting coil conductors, a driving circuit and a detection coil arranged in parallel to derive the position of an indicator, wherein, in a first period, the plurality of transmitting coil conductors are respectively connected to the driving circuit in a first connection manner, and the detection coil is used to detect the alternating magnetic field generated by the indicator according to the alternating magnetic field simultaneously transmitted from the plurality of transmitting coil conductors by the alternating current supplied from the driving circuit, thereby obtaining a first result; in a second period different from the first period, the plurality of transmitting coil conductors are respectively connected to the driving circuit in a second connection manner different from the first connection manner, and the detection coil is used to detect the alternating magnetic field generated by the indicator according to the alternating magnetic field simultaneously transmitted from the plurality of transmitting coil conductors by the alternating current supplied from the driving circuit, thereby obtaining a second result; and the position of the indicator is derived based on the first and second results.

[0012] A sensor device according to the present invention is a sensor device for deriving the position of a pointer, comprising a plurality of transmitting coil conductors arranged in parallel, a drive circuit, a detection coil, and an integrated circuit connected to the plurality of transmitting coil conductors, the drive circuit, and the detection coil. During a first period, the integrated circuit connects the plurality of transmitting coil conductors to the drive circuit in a first connection manner, uses the detection coil to detect an alternating magnetic field generated by the pointer in response to an alternating magnetic field simultaneously transmitted from the plurality of transmitting coil conductors by an alternating current supplied from the drive circuit, thereby obtaining a first result. During a second period different from the first period, the integrated circuit connects the plurality of transmitting coil conductors to the drive circuit in a second connection manner different from the first connection manner, uses the detection coil to detect an alternating magnetic field generated by the pointer in response to an alternating magnetic field simultaneously transmitted from the plurality of transmitting coil conductors by an alternating current supplied from the drive circuit, thereby obtaining a second result. The integrated circuit derives the position of the pointer based on the first and second results.

[0013] [Effects of the Invention]

[0014] According to the present invention, since an alternating magnetic field can be simultaneously transmitted from multiple transmitting coil conductors in each of the first period and the second period, and the signal detected by the detection coil can be separated according to each transmitting coil conductor, the S / N ratio of the pen signal received in the sensor controller can be improved without reducing the frequency of position detection and without increasing the circuit scale of the sensor controller. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a diagram showing the configuration of a position detection system 1 according to the first embodiment of the present invention.

[0016] Figure 2 Yes Figure 1 FIG. 1 is a diagram showing the internal structure of the switch unit 30.

[0017] Figure 3 1 and 2 are diagrams showing the state of the switch unit 30 when the sensor controller 31 detects the position of the electromagnetic induction pen P.

[0018] Figure 4 1 and 2 are diagrams showing the state of the switch unit 30 when the sensor controller 31 detects the position of the electromagnetic induction pen P.

[0019] Figure 5 1 and 2 are diagrams showing the state of the switch unit 30 when the sensor controller 31 detects the position of the electromagnetic induction pen P.

[0020] Figure 630 is a diagram illustrating a reception signal Rx supplied from the operational amplifier 30 e to the sensor controller 31 .

[0021] Figure 7 3 is a flowchart showing the overall flow of position detection of the electromagnetic induction pen P executed by the sensor controller 31 .

[0022] Figure 8 3 is a flowchart showing the overall flow of position detection of the electromagnetic induction pen P executed by the sensor controller 31 .

[0023] Figure 9 3 is a flowchart showing the overall flow of position detection of the electromagnetic induction pen P executed by the sensor controller 31 .

[0024] Figure 10 This is a diagram illustrating a received signal Rx according to a first comparative example of the first embodiment of the present invention.

[0025] Figure 11 This is a diagram illustrating a received signal Rx according to a second comparative example of the first embodiment of the present invention.

[0026] Figure 12 The electromagnetic induction pen P is located in the loop coil LCy m In the above case, the loop coil LCy m This diagram shows the results of a simulation of the level of the pen signal received by the sent alternating magnetic field (the level after separation in the case of separation).

[0027] Figure 13 It is a diagram showing the configuration of a position detection system 1 according to a second embodiment of the present invention.

[0028] Figure 14 Yes Figure 13 FIG. 1 is a diagram showing the internal structure of the switch unit 30.

[0029] Figure 15 1 and 2 are diagrams showing the state of the switch unit 30 when the sensor controller 31 detects the position of the electromagnetic induction pen P.

[0030] Figure 16 1 and 2 are diagrams showing the state of the switch unit 30 when the sensor controller 31 detects the position of the electromagnetic induction pen P.

[0031] Figure 17 1 and 2 are diagrams showing the state of the switch unit 30 when the sensor controller 31 detects the position of the electromagnetic induction pen P.

[0032] Figure 18 It is a diagram showing the configuration of a position detection system 1 according to a third embodiment of the present invention.

[0033] Figure 19 Yes Figure 18 FIG. 1 is a diagram showing the internal structure of the switch unit 30.

[0034] Figure 20 1 and 2 are diagrams showing the state of the switch section 30 when the sensor controller 31 detects the position of the finger F. FIG.

[0035] Figure 21 1 and 2 are diagrams showing the state of the switch unit 30 when the sensor controller 31 detects the position of the electromagnetic induction pen P.

[0036] Figure 22 1 and 2 are diagrams showing the state of the switch unit 30 when the sensor controller 31 detects the position of the electromagnetic induction pen P.

[0037] Figure 23 1 and 2 are diagrams showing the state of the switch unit 30 when the sensor controller 31 detects the position of the electromagnetic induction pen P.

[0038] Figure 24 (a) to (c) are schematic representations of Figure 21 to Figure 23 d) to (f) show the supply method of alternating current to the six linear electrodes EL by the methods shown in (a) to (c). m ~EL m+5 Supply AC current i A 、i B Diagram of the equivalent circuit of the case.

[0039] Figure 25 3 is a flowchart showing the overall flow of position detection of the electromagnetic induction pen P executed by the sensor controller 31 .

[0040] Figure 26 3 is a flowchart showing the overall flow of position detection of the electromagnetic induction pen P executed by the sensor controller 31 .

[0041] Figure 27 3 is a flowchart showing the overall flow of position detection of the electromagnetic induction pen P executed by the sensor controller 31 .

[0042] Figure 28 (a) to (c) represent Figure 24 In the connection methods (a) to (c), the electromagnetic induction pen P is located in the analog loop coil PLC m+1 In the case of the above, the reception signal Rx_EMR (-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 ), (d) and (f) are respectively obtained after obtaining the received signal E shown in (a). m,n ,E m+1,n ,E m+2,n The signal obtained in this case.

[0043] Figure 29 3 and 4 are diagrams for explaining angles θ and φ showing the inclination of the electromagnetic induction pen P.

[0044] Figure 30 This is a diagram showing the levels of pen signals obtained when (θ, φ) = (0, 0).

[0045] Figure 31 This is a diagram showing the levels of pen signals obtained when (θ, φ) = (60, 0).

[0046] Figure 32 This is a diagram showing the levels of pen signals obtained when (θ, φ) = (60, 90).

[0047] Figure 33 This is a diagram showing the levels of pen signals obtained when (θ, φ) = (60, 180).

[0048] Figure 34 (a) is a diagram illustrating a method of selecting the linear electrode EL in the position detection system 1 according to the third embodiment of the present invention, and (b) is a diagram illustrating a method of selecting the linear electrode EL in the position detection system 1 according to the fourth embodiment of the present invention.

[0049] Figure 35 (a), (b), and (c) are diagrams showing methods for selecting the linear electrode EL in CDM1, CDM3, and CDM7, respectively; (d), (e), and (f) are diagrams showing the levels of the pen signals obtained by CDM1, CDM3, and CDM7, respectively (the levels after restoration operation when restoration operation is performed).

[0050] Figure 36 (a) and (b) are graphs showing pen signal levels obtained when using CDM1, CDM3, and CDM7, respectively. (c) is a graph in which measured values ​​and theoretical values ​​are plotted for peak values ​​of pen signal levels in CDM1, CDM3, and CDM7, respectively.

[0051] Figure 37 This is a diagram showing the levels of pen signals obtained when (θ, φ) = (0, 0).

[0052] Figure 38 This is a diagram showing the levels of pen signals obtained when (θ, φ) = (60, 0).

[0053] Figure 39 This is a diagram showing the levels of pen signals obtained when (θ, φ) = (60, 90).

[0054] Figure 40 This is a diagram showing the levels of pen signals obtained when (θ, φ) = (60, 180).

[0055] Figure 41 (a), (b), and (c) are diagrams showing situations where an alternating magnetic field is sent from an analog loop coil PLC using different methods, and (d), (e), and (f) are diagrams showing the levels of pen signals obtained when an alternating magnetic field is sent from an analog loop coil PLC using the methods shown in (a), (b), and (c), respectively. DETAILED DESCRIPTION

[0056] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0057] Figure 1 This figure shows the configuration of a position detection system 1 according to a first embodiment of the present invention. As shown in this figure, position detection system 1 includes an electromagnetic induction pen P and a position detection device 3. The electromagnetic induction pen P is a pen compatible with EMR position detection and has an internal resonant circuit including a coil and a capacitor.

[0058] Position detection device 3 is a device that detects the position of an electromagnetic induction pen P using the EMR method. It is composed of multiple loop coils LCx (detection coils), multiple loop coils LCy (transmitting coil conductors), a switch unit 30, a sensor controller 31, and a main processor 32. A typical example of position detection device 3 is a tablet terminal or laptop computer with a display that also serves as a touch screen. However, position detection device 3 can also be configured using a digitizer or other device without a display.

[0059] The x and y directions shown in the figure are both directions within the touch surface and are orthogonal to each other. Multiple loop coils LCx are formed to extend in the y direction (first direction) and are arranged in parallel in the x direction (second direction). Conversely, multiple loop coils LCy are formed to extend in the x direction and are arranged in parallel in the y direction. Each loop coil LCx and each loop coil LCy are connected to the switch unit 30 at both ends.

[0060] The switch unit 30 is a switch assembly consisting of multiple loop coils LCx and multiple switches for switching the connection between the multiple loop coils LCy and the sensor controller 31. The switch unit 30 can be provided within a dedicated circuit board or integrated circuit, or within the same integrated circuit as the sensor controller 31. The switching state of the switch unit 30 is controlled by the sensor controller 31.

[0061] Figure 2 This figure shows the internal structure of the switch unit 30. For simplicity, only five loop coils LCx and three loop coils LCy (loop coils LCx n-2 ~LCx n+2 , loop coil LCy m ~LCy m+2 This is important for the following Figures 3 to 5 The same is true. Figure 2 As shown, the switch section 30 includes two types of switches 30 a and 30 b , a drive circuit 30 c , a wiring section 30 d , and an operational amplifier 30 e .

[0062] Switch 30a is a structure for supplying an alternating current Tx (used to generate an alternating magnetic field on the touch surface) and a ground potential to the loop coil LCy. It has an output pin at each end of the loop coil LCy and two input pins for each output pin. A driver circuit 30c supplies the AC current to one of the two input pins, while the driver circuit 30c supplies the ground potential to the other. Under control of the sensor controller 31, switch 30a connects each output pin to one of the corresponding two input pins.

[0063] The drive circuit 30c generates an AC current based on the AC current Tx supplied from the sensor controller 31 and supplies it to each loop coil LCy via the switch 30a. The process by which the drive circuit 30c generates the AC current based on the AC current Tx typically involves amplifying the AC current Tx. The drive circuit 30c also supplies a ground potential to each loop coil LCy via the switch 30a. The drive circuit 30c supplies the generated AC current to one of the two input pins corresponding to each loop coil LCy within the switch 30a, and supplies the ground potential to the other of the two input pins corresponding to each loop coil LCy within the switch 30a.

[0064] Switch 30b and wiring 30d are used to supply pen signals received by each loop coil LCx (signals represented 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 operational amplifier 30e. Switch 30b has an input pin located at each end of loop coil LCx and four output pins located for each input pin. Under control of sensor controller 31, switch 30b connects each input pin to one of the four corresponding output pins.

[0065] The wiring portion 30d is configured to include two wirings L1 and L2. The wiring L1 is grounded. The two output pins of each input pin of the switch 30b are provided corresponding to the two wirings L1 and L2 and are connected to the corresponding wirings.

[0066] The operational amplifier 30e is a circuit that generates a received signal Rx by amplifying the voltage difference between its input terminal and the ground terminal. Together with the sensor controller 31, it forms a circuit for receiving pen signals. The input terminal of the operational amplifier 30e is connected to the wiring L2 of the wiring section 30d. As a result, the received signal Rx is an amplified 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 can also be used.

[0067] return Figure 1 The sensor controller 31 is an integrated circuit that detects the position of the electromagnetic induction pen P within the touch surface using EMR. The sensor controller 31 also demodulates the pen signal transmitted by the electromagnetic induction pen P to acquire data transmitted by the electromagnetic induction pen P. The sensor controller 31 sequentially supplies the detected position and acquired data to the main processor 32.

[0068] The main processor 32 uses the position and data supplied by the sensor controller 31 to perform processes such as moving the cursor displayed on the display surface and generating stroke data representing the trajectory of the electromagnetic induction pen P within the touch surface. Regarding the stroke data, the main processor 32 also performs processes such as rendering and displaying the generated stroke data, generating and recording digital ink containing the generated stroke data, and transmitting the generated digital ink to an external device in response to user instructions.

[0069] Below, refer to Figures 3 to 5 , the position detection processing of the electromagnetic induction pen P performed by the sensor controller 31 will be described in detail.

[0070] Figures 3 to 5The diagrams are diagrams showing the states of the switch section 30 when the sensor controller 31 detects the position of the electromagnetic induction pen P. The sensor controller 31 switches any one of the loop coils LCx (in Figures 3 to 5 The middle is the loop coil LCx n ) is connected to the operational amplifier 30e, three adjacent loop coils LCy are selected in sequence as a group, and the control switch 30a is processed each time so that the three loop coils LCy constituting the selected group are connected to the drive circuit 30c in three connection methods with different connection polarities.

[0071] Figures 3 to 5 Indicates the connection under the above three connection modes. Figure 3 In the example, from the perspective of the drive circuit 30c, the loop coil LCy m Connect the loop coil LCy in a counterclockwise direction (marked as "-1" in the figure) m+1 Connect clockwise (marked as "1" in the figure) and finally connect the loop coil LCy m+2 Connect counterclockwise. Figure 4 In the example, from the perspective of the drive circuit 30c, the loop coil LCy is connected clockwise. m , connect the loop coil LCy counterclockwise m+1 , connect the loop coil LCy counterclockwise m+2 .exist Figure 5 In the example, when viewed from the driving circuit 30c, the loop coil LCy is connected counterclockwise. m , connect the loop coil LCy counterclockwise m+1 , connect the loop coil LCy clockwise m+2 .

[0072] Figure 6 This is a diagram illustrating the reception signal Rx supplied from the operational amplifier 30e to the sensor controller 31 as a result of the above connection. The pen signal detection periods T1 to T3 (first to third periods) shown in the figure are respectively Figures 3 to 5 In addition, in fact, the sending time of the alternating magnetic field is configured in the first half of each signal detection period, but Figure 6 In addition, the actual received signal Rx decays over time, but for ease of understanding, Figure 6 These aspects are discussed later in Figure 10 and Figure 11 The same is true in Chinese.

[0073] Reference Figure 6 It can be seen that during the pen signal detection period, the alternating magnetic field sent by T1 is in the loop coil LCy m+1 and loop coil LCym , LCy m+2 This is because, as mentioned above, the loop coil LCy m+1 Clockwise rotation, and the loop coil LCy m and LCy m+2 As a result, if the coils LCy from each loop are m ~LCy m+2 The alternating magnetic field sent out is in the loop coil LCx n The level of the received pen signal is recorded as level E m、n ~E m+2、n , then Figure 6 As shown, the reception signal Rx (result value) supplied from the operational amplifier 30e to the sensor controller 31 during the pen signal detection period T1 is expressed as -E m、n +E m+1、n ~E m+2、n The same is true for the pen signal detection periods T2 and T3, which are expressed as +E m、n -E m+1、n -E m+2、n 、-E m、n -E m+1、n +E m+2、n .

[0074] The vector d is represented by the following formula (1): LC The vector of the received signal Rx received during each of the pen signal detection periods T1 to T3 is recorded in vector form. LC As shown in the last row of equation (1), it can be transformed into a 3×3 matrix F representing the connection polarity in each signal detection period and a matrix E representing the level. m、n ~E m+2、n In addition, the matrix F shown in formula (1) is a 3×3 Walsh code.

[0075] [Mathematical formula 1]

[0076]

[0077] The sensor controller 31 controls the vector d LC Perform the calculation shown on the left side of the following equation (2) to separate and obtain the level E m、n ~E m+2、n . Among them, the matrix F shown in formula (2) -1 Since it is the inverse matrix of the matrix F, the operation shown on the left side of the formula (2) becomes the restoration operation corresponding to the connection polarity of the loop coil LCx in each of the above connection methods. As shown in the formula (2), if the matrix F is multiplied by the matrix F -1, then it becomes the unit matrix I, so the sensor controller 31 can perform the restoration operation, as shown on the right side of equation (2), according to the m ~LCy m+2 The alternating magnetic field sent out is separated and obtained in the loop coil LCx n The level of the received pen signal E m， n ~E m+2， n .

[0078] [Mathematical formula 2]

[0079]

[0080] The sensor controller 31 performs the same calculation as equation (2) on each group of loop coils LCy, thereby separating and acquiring the signals from the plurality of loop coils LCy. m When an alternating magnetic field is sent out, the loop coil LCx n The sensor controller 31 performs the same process while changing the loop coil LCx that receives the pen signal, thereby obtaining the level of the pen signal received from multiple loop coils LCy. m The sensor controller 31 then derives the position of the electromagnetic induction pen P based on the distribution of the pen signal levels obtained within the touch surface. Specifically, the position corresponding to the vertex of the distribution is derived as the position of the electromagnetic induction pen P.

[0081] Figures 7 to 9 This is a flowchart showing the overall flow of position detection of the electromagnetic induction pen P executed by the sensor controller 31 of this embodiment. Figure 7 The sensor controller 31 before detecting the electromagnetic induction pen P selects a loop coil LCx at the end and connects it to the operational amplifier 30e (step S1), and selects three loop coils LCy from the end and connects them in the first connection mode (for example, Figure 3 The circuit 30 is connected to the driving circuit 30c (step S2).

[0082] Next, the sensor controller 31 begins transmitting an alternating magnetic field from the selected loop coil LCy group (step S3). Specifically, it begins supplying an alternating current Tx to the drive circuit 30c. This generates an alternating current in either a counterclockwise or clockwise direction in each of the three loop coils LCy. As a result, alternating magnetic fields corresponding to the direction of the alternating current are transmitted from each of the three loop coils LCy. The sensor controller 31 then temporarily stores the level of the received signal Rx output by the operational amplifier 30e based on the alternating magnetic field transmitted in step S3 (step S4).

[0083] Next, the sensor controller 31 determines whether the processing of steps S3 to S4 has been tried in all connection modes (step S5). Specifically, it determines whether Figures 3 to 5 The processing of steps S3 to S4 is tried in all three connection modes shown in FIG. In this judgment, the sensor controller 31, which is judged not to have been tried, controls the switch 30a to connect the three loop coils LCy selected in the following connection mode (for example, Figure 3 The connections shown are followed by Figure 4 The connection method shown in Figure 4 The connections shown are followed by Figure 5 The circuit 30 is connected to the driving circuit 30c (step S6) and returns to step S3.

[0084] On the other hand, the sensor controller 31 that has determined that a trial has been performed in step S5 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 the multiple trials in step S4 (step S7). Specifically, the vector d LC Multiply by the inverse matrix F -1 Operation (restore operation).

[0085] Next, the sensor controller 31 determines whether the selection of all loop coils LCy has been completed (step S8). If it is determined that the selection has not been completed, the sensor controller 31 selects three loop coils LCy adjacent to the three loop coils LCy selected last (the loop coils selected in step S2 or step S9), and controls the switch 30a to connect the three loop coils LCy in the first connection mode (for example, Figure 3 After the loop coil LCx is connected to the drive circuit 30c (see the connection method shown in step S9), the process returns to step S3. If the sensor controller 31 determines that the loop coil LCx selection has been completed in step S8, it determines whether all loop coils LCx have been selected (step S10). If it determines that the loop coil LCx selection has not been completed, it selects a loop coil LCx adjacent to the previously selected loop coil LCx (the loop coil selected in step S1 or step S11) and connects it to the operational amplifier 30e (step S11), and the process returns to step S3.

[0086] The sensor controller 31, which has determined that the operation is finished in step S10, determines whether a pen signal ( Figure 8 In one example, the result of this determination is affirmative if there is a level exceeding a predetermined value, and negative otherwise.

[0087] The sensor controller 31 that determines that no pen signal is detected in step S12 returns to Figure 7 On the other hand, the sensor controller 31 determines that the pen signal is detected based on the Figure 7 The position of the electromagnetic induction pen P is derived from the level of the pen signal for each combination of the loop coil LCy and the loop coil LCx derived in step S7 and is output to the main processor 32 (step S13).

[0088] Next, 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), the sensor controller 31 determines 3n (n is a natural number, typically n=1, where 3n is a number smaller than the total number of loop coils LCy) loop coils LCy and a predetermined number (typically 3 or 4, which is smaller than the total number of loop coils LCx) of loop coils LCx as selection targets (step S14).

[0089] Next, the sensor controller 31 selects the loop coil at the end of the selected loop coils LCx and connects it to the operational amplifier 30e (step S15). Then, the sensor controller 31 selects three loop coils LCy from the end of the selected loop coils LCy and controls the switch 30a to connect the three selected loop coils LCy in the first connection mode (for example, Figure 3 The device is connected to the drive circuit 30c (step S16).

[0090] Transfer to Figure 9 Then, the sensor controller 31 performs Figure 7 and Figure 8 The same processing as steps S3 to S12 is performed (steps S17 to S26). However, the processing here differs from steps S3 to S12 in that, while in step S4 only the level of the received signal Rx is temporarily stored, in step S18 a series of digital values ​​(digital values ​​obtained through sampling) constituting the received signal Rx are also stored. In step S8, it is determined whether all loop coils LCy have been selected, and in step S22, it is determined whether all loop coils LCy selected in step S14 have been selected. In step S10, it is determined whether all loop coils LCx selected in step S14 have been selected, and in step S24, it is determined whether all loop coils LCx selected in step S14 have been selected.

[0091] Having determined in step S26 that a pen signal has been detected, the sensor controller 31 derives the position of the electromagnetic induction pen P, obtains the data transmitted by the electromagnetic induction pen P, and outputs it to the main processor 32 (step S27). Specifically, the sensor controller 31 derives the position of the electromagnetic induction pen P based on the pen signal levels for each combination of loop coils LCy and LCx derived in step S21. Furthermore, the sensor controller 31 demodulates the series of digital values ​​stored in step S18 for the combination of loop coils LCy and LCx closest to the derived position to obtain the data transmitted by the electromagnetic induction pen P. After completing step S27, the sensor controller 31 returns to step S14 to continue processing.

[0092] The position detection method of this embodiment improves the S / N ratio of pen signals received by sensor controller 31 without reducing the frequency of position detection or increasing the circuit scale of sensor controller 31. This effect is described in detail below, comparing this method with a comparative example that uses a different method to transmit an alternating magnetic field.

[0093] Figure 10 This diagram illustrates the received signal Rx of the first comparative example. In this comparative example, the sensor controller 31 transmits an alternating magnetic field from only one loop coil LCy during each pen signal detection period. In this case, since the level of the received pen signal based on the alternating magnetic field transmitted from one loop coil LCy is obtained during each pen signal detection period, the sensor controller 31 can obtain the level of the received pen signal based on the alternating magnetic field transmitted from each loop coil LCy without performing the aforementioned calculations.

[0094] Figure 11 : is a diagram illustrating the received signal Rx of the second comparative example. The sensor controller 31 of this comparative example simultaneously sends out alternating magnetic fields from three adjacent loop coils LCy during each pen signal detection period, similar to the present embodiment. However, the sensor controller 31 of this comparative example connects all the loop coils LCy to the drive circuit 30c in the same orientation (right-handed or left-handed). In this case, in the above-mentioned calculation, it is impossible to separate the levels of the pen signals received based on the alternating magnetic fields sent out from each loop coil LCy. However, the sensor controller 31 can treat the received signal Rx obtained by sending out the alternating magnetic field from the three loop coils LCy as a signal obtained by sending out the alternating magnetic field from the loop coil LCy located at the center of the three loop coils LCy, and derive the position of the electromagnetic induction pen P.

[0095] Figure 12 The electromagnetic induction pen P is located in the loop coil LCy mIn the above case, the loop coil LCy m The figure shows the result of simulating the level of the pen signal received by the alternating magnetic field sent out (the level after separation in the case of separation acquisition). Figure 6 )、First Comparative Example( Figure 10 )、Second Comparative Example( Figure 11 ) As shown in the figure, the position detection method according to this embodiment can significantly improve the reception level of the pen signal compared to the first and second comparative examples. This is because the position detection method according to this embodiment can be used to obtain the position of the pen signal from each loop coil LCy. m The pen signal detection period of the pen signal received by the sensor controller 31 is tripled compared to the first and second comparative examples. As described above, when the pen signal detection period of the pen signal in the sensor controller 31 is increased by N times, the level of the received pen signal is increased by N times, while the level of the received noise remains at N. 1 / 2 Therefore, according to the position detection method of this embodiment, it can be said that the S / N ratio of the pen signal received by the sensor controller 31 can be improved.

[0096] Furthermore, the position detection method of this embodiment allows a single receiving circuit to simultaneously receive pen signals corresponding to multiple loop coils LCy during each of multiple pen signal detection periods, and to separate the received signal Rx into components for each loop coil LCy. This eliminates the need to extend the pen signal transmission period to improve the S / N ratio, nor does it require additional receiving circuits to receive pen signals in parallel from multiple loop coils LCx. Therefore, the position detection method of this embodiment can improve the S / N ratio of pen signals received by the sensor controller 31 without reducing the frequency of position detection or increasing the circuit size of the sensor controller 31.

[0097] Here, the noise level remains at N when the pen signal detection period of the pen signal in the sensor controller 31 is increased by N times. 1 / 2 Times this.

[0098] If the received signal Rx obtained during the k-th pen signal detection period is set to X k , and its variance is expressed as V(X k ), then according to the additivity of the variance, the N-times received signals X1 to X2 obtained during the first to N-th pen signal detection period are N The variance V of the added signal (hereinafter referred to as the “added signal”) TOTAL As shown in the following formula (3), it is represented by the sum of the variances of the reception signal Rx in each pen signal detection period.

[0099] [Mathematical formula 3]

[0100]

[0101] If we only focus on the noise component included in the received signal Rx, we assume that the noise has the same value during all signal detection periods. Therefore, the variance V of the sum signal is TOTAL It can be further expressed as the following equation (4): wherein V and σ are the variance and standard deviation in each pen signal detection period, respectively.

[0102] [Formula 4]

[0103]

[0104] The amount of noise present in the summed signal is determined by the standard deviation σ of the summed signal. TOTAL According to formula (4), the standard deviation σ TOTAL As shown in the following equation (5), it can be understood that when the pen signal detection period of the pen signal in the sensor controller 31 is multiplied by N, the noise level remains at N. 1 / 2 times.

[0105] [Formula 5]

[0106]

[0107] As described above, according to the position detection system 1 of this embodiment, the S / N ratio of the pen signal received by the sensor controller 31 can be improved without reducing the frequency of position detection and increasing the circuit scale of the sensor controller 31 .

[0108] In addition, in this embodiment, an example is described in which the matrix F shown in equation (1) is a matrix represented by a 3×3 Walsh code. However, a matrix represented by a code other than a Walsh code, such as an OVSF code, an M-sequence code, or a Baker code, can also be appropriately used as the matrix F (that is, the connection method of the loop coil LCy during each signal detection period is set so that the matrix F corresponds to these codes).

[0109] To explain this in general terms, when alternating magnetic fields are simultaneously transmitted from k loop coils LCy (i.e., while the sensor controller 31 connects any loop coil LCx to the operational amplifier 30e via control of the switch 30b, the k adjacent loop coils LCy are sequentially selected as a group, and the switch 30a is controlled so that the k loop coils LCy constituting the selected group are connected to the drive circuit 30c in k different connection configurations with different polarities), if the rank of the matrix F (a matrix with k rows and k columns), which is the coefficient matrix of the simultaneous equations represented by the following equation (6), is equal to k, then the connection configuration of the loop coils LCy during each signal detection period can be determined based on the matrix F. In other words, if the column vectors of the matrix F (the plurality of vectors representing the connection states of the loop coils LCy) are linearly independent of each other, then the connection configuration of the loop coils LCy during each signal detection period can be determined based on the matrix F. This is because in all cases, equation (6) always has a solution.

[0110] [Formula 6]

[0111]

[0112] Each element of such a matrix F does not necessarily need to be "-1" or "1." For example, if k = 2, the rank of either matrix F shown in Equation (7) or Equation (8) below is equal to 2, and thus can be used to determine the connection method of the loop coil LCy during each signal detection period. When using the matrix F shown in Equation (8), the drive circuit 30c supplies an AC current with the same direction but a different level (specifically, an AC current with the same direction but twice the level) to the loop coil LCy corresponding to element "2" as to the loop coil LCy corresponding to element "1."

[0113] [Formula 7]

[0114]

[0115] In addition, in this embodiment, the inverse matrix F of the matrix F is used. -1 This is an example of performing a restoration operation, but a matrix other than an inverse matrix can also be used for restoration operations. LC Taking the case of as an example, an example of a restoration operation using the matrix F itself as a matrix that is not the inverse matrix of the matrix F will be described.

[0116] In this example, first, the matrix F for restoration and the level of the reception signal Rx in the pen signal detection period T1 to T3 are used. m,n +E m+1,n -E m+2,n 、+Em,n -E m+1,n -E m+2,n 、-E m,n -E m+1,n +E m+2,n The level of the received signal Rx corresponding to the case where all columns of the matrix F are 1 is derived. Specifically, the simultaneous equations shown in the following formula (9) are solved to obtain a, b, and c, and a+b+c is derived. From this, 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 .

[0117] [Formula 8]

[0118]

[0119] Next, as shown in the following equation (10), a column with all elements set to 1 is added to the beginning of the matrix F, and in the vector d LC Add the value +E at the beginning of m， n +E m+1， n +E m+2， n After the row, the matrix F is combined with the vector d LC By multiplying them, we obtain a result obtained by linearly (specifically, 4 times) amplifying the result of the operation of formula (9).

[0120] [Formula 9]

[0121]

[0122] Thus, when using a matrix F that is not the inverse of the matrix F -1 When performing a restoration operation on a matrix of F, it is necessary to derive the level of the received signal Rx equivalent to the case where all columns of the matrix F are 1, but this is different from using the inverse matrix F of the matrix F. -1 The same is true for the case of restoration operation, the level E can be separated and obtained. m、n ~E m+2、n+1 .

[0123] In addition, in formula (10), the result of the calculation result of formula (2) is amplified by 4 times, but it is preferable to enlarge the calculation result in this way because it improves the accuracy of the subsequent calculation. The same applies to the inverse matrix F of the matrix F. -1 The following describes the situation where the recovery calculation is performed with a specific example.

[0124] Vector d when the matrix F is a 4×4 Walsh code LC It is expressed as the following equation (11): wherein the vector e is a vector representing the level of the pen signal corresponding to each of the four loop coils LCy.

[0125] [Formula 10]

[0126]

[0127] The inverse matrix F of the matrix F shown in formula (11) is -1 It is expressed as formula (12).

[0128] [Mathematical formula 11]

[0129]

[0130] Therefore, when performing the recovery calculation of the vector e, if the inverse matrix F -1 Multiply by 4, as shown in the following formula (13), then the inverse matrix F can be performed -1 The recovery calculation simultaneously obtains a vector having four times the level of the original vector e.

[0131] [Mathematical formula 12]

[0132]

[0133] Next, a position detection system 1 according to a second embodiment of the present invention will be described.

[0134] Figure 13 1 is a diagram showing the configuration of the position detection system 1 of this embodiment. Figure 1 As can be seen, the position detection system 1 of this embodiment differs from the first embodiment in that two adjacent loop coils LCy in the y direction are arranged in an overlapping manner. In other respects, the position detection system 1 of this embodiment is identical to the position detection system 1 of the first embodiment, so the following description will focus on the differences from the position detection system 1 of the first embodiment.

[0135] Figure 14 This figure shows the internal structure of the switch unit 30 arranged in the position detection device 3 constituting the position detection system 1 of the second embodiment of the present invention. In this figure, only five loop coils LCx and seven loop coils LCy (loop coils LCx n-2 ~LCx n+2 , loop coil LCy m-2 ~LCy m+4 This is important for the following Figures 15 to 17 The same is true. Figure 14 and Figure 1 It can be seen that the internal structure of the switch section 30 of the present embodiment is the same as that of the switch section 30 of the first embodiment, except that two loop coils LCy adjacent to each other in the y direction are arranged to overlap.

[0136] Figures 15 to 17 The diagrams respectively show the states of the switch section 30 when the sensor controller 31 of the present embodiment detects the position of the electromagnetic induction pen P. The sensor controller 31 of the present embodiment is similar to the sensor controller 31 of the first embodiment. When any loop coil LCx (in Figures 15 to 17 The middle is the loop coil LCx n ) is connected to the operational amplifier 30e, three adjacent loop coils LCy are selected in sequence as a group, and the control switch 30a is processed each time so that the three loop coils LCy constituting the selected group are connected to the drive circuit 30c in three connection methods with different connection polarities.

[0137] The details of the three connection methods are the same as those in the first embodiment. However, in this embodiment, two adjacent loop coils LCy in the y direction are overlapped, so the current paths cross between the two adjacent loop coils LCy. However, even if such a crossover occurs, the level E can be separated and obtained by the same restoration operation as in the first embodiment. m、n ~E m+2、n Therefore, according to the position detection method of this embodiment, as in the first embodiment, it can be said that the S / N ratio of the pen signal received in the sensor controller 31 can be improved without reducing the frequency of position detection and without increasing the circuit scale of the sensor controller 31.

[0138] Next, a position detection system 1 according to a third embodiment of the present invention will be described.

[0139] Figure 18 This figure shows the configuration of a position detection system 1 according to this embodiment. The differences between the position detection system 1 according to this embodiment and the position detection system 1 according to the second embodiment are that the position detection device 3 also supports capacitance-based position detection of a finger F, that the position detection device 3 includes multiple linear electrodes EL instead of the multiple loop coils LCy, and that the switch unit 30 has an internal structure. In other respects, the position detection system 1 according to this embodiment is the same as the position detection system 1 according to the second embodiment, so the following description will focus on the differences from the position detection system 1 according to the second embodiment.

[0140] The plurality of linear electrodes EL are formed so as to extend in the x direction and are arranged in a row in the y direction. Each linear electrode EL is connected to the switch section 30 at both ends.

[0141] The switch unit 30 of this embodiment is a switch assembly consisting of a plurality of loop coils LCx and a plurality of switches for switching the connection between the plurality of linear electrodes EL and the sensor controller 31. As described in the first embodiment, the switch unit 30 can be provided in a dedicated circuit board or integrated circuit, or 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.

[0142] Figure 19 This figure shows the internal structure of the switch unit 30 of this embodiment. For simplicity, only five loop coils LCx and six linear electrodes EL (loop coils LCx n-2 ~LCx n+2 , linear electrode EL m ~EL m+5 This is important for the following Figures 20 to 23 The same is true. Figure 19 As shown, the switch unit 30 of this embodiment has Figure 14 In addition to the switch 30b, wiring portion 30d, and operational amplifier 30e shown, the structure further includes switches 30f to 30j, a drive circuit 30k, and an operational amplifier 30m. Figure 2 The switch 30 a and the drive circuit 30 c shown are not included in the switch unit 30 of this embodiment.

[0143] The switch 30f is configured to supply an alternating current Tx_EMR to the multiple linear electrodes EL, generating an alternating magnetic field on the touch surface. It 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). Under control of the sensor controller 31, the switch 30f connects each input pin to one of the output pins for each linear electrode EL.

[0144] The driving circuit 30k generates the following alternating current i according to the alternating current Tx_EMR supplied from the sensor controller 31. A 、i B , and supplies the current to each linear electrode EL via the switch 30f. The driving circuit 30k is configured to supply an AC current i to one of the two input pins corresponding to each linear electrode EL. A , supplying AC current i to the other side B .

[0145] AC current i A For example, the current is generated by amplifying the AC current Tx_EMR using a buffer circuit. B So the AC current iA The currents generated by the two currents are in a manner such that their respective time differentials are in anti-phase with each other. If this relationship is expressed mathematically, it becomes the following equation (14).

[0146] [Mathematical formula 13]

[0147]

[0148] A typical AC current i that satisfies the relationship of formula (14) is B It is expressed by the following formula (15). Where A is an arbitrary constant. When A=0, the AC current i B becomes an alternating current i A In this case, the AC current i A and the AC current i B On the other hand, when A is greater than the AC current i A When the AC current i A and the AC current i B The AC current i A The inversion signal can be generated using an inversion buffer circuit, for example. Figure 19 An example using an inverting buffer circuit is shown.

[0149] [Formula 14]

[0150]

[0151] Accepts AC current i A 、i B The potential of the other end of each linear electrode EL supplied with the AC current i is preferably set to A The potential generated at one end of the linear electrode EL is equal to the potential generated when an alternating current i is supplied. B The potential at the midpoint of the potential generated at one end of the linear electrode EL. When A=0, this potential is 0 (ie, ground potential).

[0152] The switch 30g is configured to supply a touch detection signal Tx_TP for detecting the position of a finger F to the plurality of linear electrodes EL. It comprises a set of input and output pins provided for each linear electrode EL. The touch detection signal Tx_TP is supplied to each input pin from the sensor controller 31. Each output pin is connected to one end of the corresponding linear electrode EL in the x-direction (longitudinal direction). The switch 30g functions to connect each input pin to the corresponding output pin under control of the sensor controller 31.

[0153] The switch 30j is a structure for switching the other end of the linear electrode EL in the x direction (longitudinal direction) between a state connected to the potential of the above-mentioned midpoint and a floating state not connected to any part. Figure 19 The figure shows the case where the potential of the midpoint is the ground potential. Figure 19 As shown in FIG, the switch 30j in this case is configured to include a set of an input pin and a ground pin provided for each linear electrode EL.

[0154] 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). Meanwhile, each ground pin of the switch 30j is connected to a ground terminal supplied with a ground potential. 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. On the other hand, when the sensor controller 31 detects the position of the finger F, it is necessary to set the other end of each linear electrode EL in the x-direction to a floating state. The switch 30j switches the connection between each input pin and the corresponding ground pin under the control of the sensor controller 31.

[0155] Switches 30b, 30h, and 30i, along with wiring 30d, are configured to supply pen signals received by loop coils LCx (signals transmitted by the electromagnetic induction pen P in response to the alternating magnetic field) to an operational amplifier 30e, and to supply touch detection signals Tx_TP received by loop coils LCx to an operational amplifier 30m. The specific configuration of switches 30b and wiring 30d is the same as in the first and second embodiments.

[0156] Switch 30h connects wiring L2 to the input terminal of operational amplifier 30e and connects wiring L1 to ground under the control of sensor controller 31. Switch 30i connects wiring L2 to the input terminal of operational amplifier 30m under the control of sensor controller 31. The initial state of switches 30h and 30i is both open (disconnected).

[0157] The operational amplifier 30e is the same as the operational amplifier 30e described in the first embodiment. However, in this 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 the received signal Rx_TP using an electrostatic capacitance method by amplifying the voltage difference between the input terminal and the ground terminal. Together with the sensor controller 31, it 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 portion 30d via the switch 30i. As a result, the received signal Rx_TP becomes a signal that amplifies the signal appearing on the wiring L2. The operational amplifier 30m is provided with a parallel capacitor for removing high-frequency noise. 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.

[0158] return Figure 18 . The sensor controller 31 of this embodiment is configured to have, in addition to the functions described in the first embodiment (a function of detecting the position of the electromagnetic induction pen P within the touch surface by the EMR method and demodulating the pen signal sent by the electromagnetic induction pen P to obtain the data sent by the electromagnetic induction pen P), a function of detecting the position of the finger F on the touch surface by the electrostatic capacitance method. The detection of the position of the electromagnetic induction pen P, the acquisition of data from the electromagnetic induction pen P, and the detection of the position of the finger F are performed in a time-sharing manner. The sensor controller 31 is configured to sequentially supply the detected position and the obtained data to the main processor 32. The processing performed by the main processor 32 that receives the supply is the same as that of the first embodiment.

[0159] Below, refer to Figures 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 described in detail.

[0160] first, Figure 20 This diagram illustrates the state of the switch unit 30 when the sensor controller 31 of this embodiment detects the position of a finger F. As shown in this diagram, the sensor controller 31 controls switch 30g to connect each input pin to the corresponding output pin. This causes the sensor controller 31 to supply a touch detection signal Tx_TP to one end of each linear electrode EL in the x-direction. Furthermore, the sensor controller 31 controls switch 30j to disconnect each input pin from the corresponding ground pin, thereby placing the other end of each linear electrode EL in the x-direction in a floating state.

[0161] The specific content of the touch detection signal Tx_TP generated by the sensor controller 31 can be expressed by the matrix A shown in the following equation (16). The matrix A is a square matrix having a plurality of rows corresponding to the plurality of linear electrodes EL. 11 The left side of the subscripts (e.g., etc.) indicates the output order from the sensor controller 31, and the right side indicates the serial number of the linear electrodes EL. M is the total number of linear electrodes EL. The specific value of each element is either "1" or "-1." Matrix A is preferably an orthogonal matrix, but it does not have to be an orthogonal matrix.

[0162] [Mathematical formula 15]

[0163]

[0164] The sensor controller 31 generates a touch detection signal Tx_TP for each column of the matrix A and supplies it to each linear electrode EL. A typical example of a touch detection signal Tx_TP is a binary pulse signal that is high when the corresponding element of the matrix A is 1, and low when the corresponding element of the matrix A is 1. Hereinafter, the touch detection signal Tx_TP corresponding to a column of the matrix A is referred to as a "partial touch detection signal Tx_TP."

[0165] While supplying a partial touch detection signal Tx_TP to each linear electrode EL, the sensor controller 31 maintains the switch 30i in the connected state and sequentially connects each loop coil LCx to the operational amplifier 30m. Specifically, the sensor controller 31 controls the switch 30b so that each loop coil LCx is sequentially connected to the wiring L2 at both ends. Figure 20 The loop coil LCx is shown in n This is an example of connection to wiring L2.

[0166] Here, if the mth linear electrode EL m With the nth loop coil LCx n The electrostatic capacitance formed between mn , the touch detection signal Tx_TP is supplied to each linear electrode EL in the portion corresponding to the x-th column of the matrix A, and the n-th loop coil LCx n When connected to the operational amplifier 30 m , the reception signal Rx_TP supplied from the operational amplifier 30 m to the sensor controller 31 becomes a value represented by the following equation (17).

[0167] [Mathematical formula 16]

[0168]

[0169] Therefore, while the partial touch detection signal Tx_TP corresponding to each column of the matrix A is being supplied, the n-th loop coil LCx n The received signal Rx_TP obtained as a whole is represented by a vector b shown in the following equation (18).

[0170] [Mathematical formula 17]

[0171]

[0172] The sensor controller 31 performs the calculation shown in the left side of the following equation (19) on the vector b to separate and obtain the electrostatic capacitance C of each linear electrode EL. mn . Among them, the matrix A shown in formula (19) -1 is the inverse matrix of matrix A. As shown in formula (19), if matrix A is multiplied by matrix A -1 , then it becomes the unit matrix I, so the sensor controller 31 performs this operation, as shown on the right side of equation (19), for the n-th loop coil LCx n , can be separated and obtained from each linear electrode EL m The electrostatic capacitance C at the intersection mn .

[0173] [Mathematical formula 18]

[0174]

[0175] The sensor controller 31 performs the same calculation as equation (19) on each loop coil LCx, thereby deriving the electrostatic capacitance C at each intersection of the linear electrode EL and the loop coil LCx. mn Then, the sensor controller 31 calculates the capacitance C based on the derived capacitance C. mn The position of the finger F is derived from the distribution of the touch surface. Specifically, the position corresponding to the vertex of the distribution may be derived as the position of the finger F, similarly to the position detection of the electromagnetic induction pen P in the EMR method.

[0176] then, Figure 21 to Figure 23 The diagram shows the state of the switch unit 30 when the sensor controller 31 of this embodiment detects the position of the electromagnetic induction pen P. The sensor controller 31 of this embodiment switches the loop coil LCx to the open position by controlling the switches 30b, 30h, and 30i. n While connected to the operational amplifier 30e, the six adjacent linear electrodes EL are sequentially selected while being shifted by three. The six linear electrodes EL selected each time are connected to the driving circuit 30k in three connection configurations. The control switch 30f is thereby processed so that an AC current i is generated in half of the six linear electrodes EL. A , generating an AC current i in the remaining halfB Furthermore, the sensor controller 31 controls the switch 30 j to connect each input pin to the corresponding ground pin, thereby grounding the other end of each linear electrode EL in the x direction.

[0177] Figures 21 to 23 Indicates the AC current i under the above three connection methods A 、i B Specifically, in Figure 21 In the example, the linear electrodes EL m+1 EL m+3 EL m+5 Supply AC current i A , to the linear electrode EL m EL m+2 EL m+4 Supply AC current i B In addition, Figure 22 In the example of the linear electrode EL m+1 ~EL m+3 Supply AC current i A , to the linear electrode EL m EL m+4 EL m+5 Supply AC current i B .exist Figure 23 In the example, the linear electrodes EL m+2 ~EL m+4 Supply AC current i A , to the linear electrode EL m EL m+1 EL m+5 Supply AC current i B .

[0178] Figure 24 (a) to (c) are schematic representations of Figure 21 to Figure 23 The diagram of each AC current supply method. Figure 24 (d) to (f) are respectively used to represent Figure 24 The methods shown in (a) to (c) are to form six linear electrodes EL m ~EL m+5 Supply AC current i A 、i B As shown in these figures, when the linear electrode EL m+k and linear electrodes EL m+k+3 (where k is any one of 0, 1, and 2) When alternating currents with time differentials in opposite phases flow, regardless of the linear electrodes EL located therebetween, m+k+1 EL m+k+2Whatever the current flowing through it, it can be regarded as the current flowing through the linear electrode EL. m+k and linear electrodes EL m+k+3 Hereinafter, the loop coil is referred to as the "pseudo loop coil PLC" (transmitting coil conductor), and in particular, the linear electrode EL m+k EL m+k+3 The analog loop coil PLC is called "analog loop coil PLC m+k "Simulating loop coil PLC m+k The connection polarity is to the linear electrode EL m+k Supply AC current i A , to the linear electrode EL m+k+3 Supply AC current i B (shown as “-” in the figure) and the linear electrode EL m+k Supply AC current i B , to the linear electrode EL m+k+3 Supply AC current i A (expressed as "+" in the figure) are opposite to each other.

[0179] Figure 24 (d) shows the configuration and connection polarity of each analog loop coil PLC Figure 15 The configuration and connection polarity of each loop coil LCy shown are exactly the same. Figure 24 (e) shows the configuration of each analog loop coil PLC and the connection polarity and Figure 16 The configuration and connection polarity of each loop coil LCy shown are exactly the same. Figure 24 (f) shows the configuration of each analog loop coil PLC and the connection polarity and Figure 17 The arrangement and connection polarity of each loop coil LCy shown are exactly the same. Therefore, according to the position detection system 1 of this embodiment, the position of the electromagnetic induction pen P can be detected similarly to the position detection system 1 of the second embodiment.

[0180] More specifically, when the linear electrode EL m+k Supply AC current i A , to the linear electrode EL m+k+3 Supply AC current i B When the loop coil LCx n The level of the received pen signal is expressed as E m+k、n In the case of Figure 24 In the case of supplying the alternating current shown in (a), the reception signal Rx_EMR (result value) supplied from the operational amplifier 30e to the sensor controller 31 is expressed as -E m、n +E m+1、n -E m+2、n . Figure 24 The same applies to the case of supplying alternating current as shown in (b) and (c), which are respectively represented by E m、n -E m+1、n -E m+2、n 、-E m、n -E m+1、n +E m+2、n If expressed in vector form, the vector d is as shown in the following equation (20): EL This is the same as the vector d shown in the above formula (1) LC Exactly the same form. Moreover, the vector d EL With vector d LC Similarly, it can be transformed into a 3×3 matrix F representing the connection polarity of the analog loop coil PLC and a matrix representing the level E m、n ~E m+2、n The form of the product of vectors.

[0181] [Mathematical formula 19]

[0182]

[0183] According to the vector d EL With vector d LC As can be seen from the same form, in this embodiment, the sensor controller 31 controls the vector d EL Multiply by the inverse matrix F -1 , able to separate the PLC from the analog loop coil m ~PLC m+2 The level E of the pen signal received when the alternating magnetic field is sent out m、n sub、E m+1、n 、E m+2、n Furthermore, according to the AC current supply method of this embodiment, compared with the case where the alternating magnetic field is sent out from each of the three analog loop coils PLC individually, the length of the period during which the alternating magnetic field is sent out from each analog loop coil PLC is tripled, so the level of the received pen signal is tripled, while the level of the received noise remains at 3 times. 1 / 2 Therefore, it can be said that the S / N ratio of the pen signal received by the sensor controller 31 can also be improved by the AC current supply method of this embodiment.

[0184] Figures 25 to 27 This is a flowchart showing the overall flow of position detection of the electromagnetic induction pen P executed by the sensor controller 31 of this embodiment. Figure 25Before detecting the electromagnetic induction pen P, the sensor controller 31 first selects the loop coil LCx at the end and connects the selected loop coil LCx to the operational amplifier 30e by controlling the switch 30b (step S30). This process also includes connecting the operational amplifier 30e to the wiring L2 and grounding the wiring L1 by controlling the switch 30h, while disconnecting the operational amplifier 30m from the wiring L2 by controlling the switch 30i.

[0185] Next, the sensor controller 31 selects six linear electrodes EL from the end portion and controls the switch 30f to connect them in the first connection mode (for example, Figure 23 The control circuit 30a is connected to the drive circuit 30k (see the connection method shown in FIG. 3 ) (step S31). This process also includes grounding the other end of each linear electrode EL in the x direction by controlling the switch 30j, and not supplying the touch detection signal Tx_TP to each linear electrode EL by controlling the switch 30g.

[0186] Next, the sensor controller 31 starts to send an alternating magnetic field from the selected linear electrode EL group (step S32). Specifically, it starts to supply an alternating current Tx_EMR to the drive circuit 30k. As a result, an alternating current i is generated in each of the six linear electrodes EL. A 、i B As a result, the aforementioned pseudo loop coil PLC is formed, and an alternating magnetic field is transmitted. The sensor controller 31 then temporarily stores the level of the reception signal Rx_EMR output from the operational amplifier 30e in response to the alternating magnetic field transmitted in step S32 (step S33).

[0187] Next, the sensor controller 31 determines whether the processing of steps S32 to S33 has been tried in all connection modes (step S34). Specifically, it determines whether Figure 21 to Figure 23 The processing of steps S32 to S33 is tried in all three connection modes shown in FIG. In this judgment, the sensor controller 31, which is judged not to have been tried, controls the switch 30f to connect the selected six linear electrodes EL to the next connection mode (for example, Figure 21 The connections shown are followed by Figure 22 The connection method shown in Figure 22 The connections shown are followed by Figure 23 The circuit 30 is connected to the driving circuit 30k (step S35), and the process returns to step S32.

[0188] On the other hand, the sensor controller 31 that has determined that the trial has been performed in step S34 derives the level of the pen signal of each analog loop coil PLC based on the levels of the plurality of received signals Rx_EMR temporarily stored through the multiple trials in step S33 (step S36). Specifically, the vector d EL Multiply by the inverse matrix F -1 Operation (restore operation).

[0189] 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, the sensor controller 31 selects six linear electrodes EL by shifting three of them and connects them in the first connection mode (for example, Figure 21 After connecting the loop coil LCx to the drive circuit 30k (connection method shown in FIG. 1 ) (step S38), the process returns to step S32. If the sensor controller 31 determines in step S37 that selection has been completed for all loop coils LCx, it determines whether selection has been completed for all loop coils LCx (step S39). If it determines that selection has not been completed, it selects a loop coil LCx adjacent to the previously selected loop coil LCx (the loop coil selected in step S30 or step S40), connects it to the operational amplifier 30e through control of the switch 30b (step S40), and then returns to step S32.

[0190] The sensor controller 31, which has determined that the operation is completed in step S39, determines whether a pen signal ( Figure 26 In one example, the result of this determination is affirmative if there is a level exceeding a predetermined value, and negative otherwise.

[0191] The sensor controller 31 that determines that no pen signal is detected in step S41 returns to Figure 25 On the other hand, the sensor controller 31 determines that the pen signal is detected based on the step S30. Figure 25 The position of the electromagnetic induction pen P is derived from the level of the pen signal for each combination of the analog loop coil PLC and the loop coil LCx derived in step S36 and is output to the main processor 32 (step S42).

[0192] Next, based on the position derived in step S42 (in the case of a transition from step S56 described later, the position derived in the previous step S56), the sensor controller 31 determines 3+3n (n is a natural number, typically n=1, where 3+3n is a number smaller than the total number of linear electrodes EL) linear electrodes EL (linear electrode group) and a predetermined number (typically 3 or 4, which is smaller than the total number of loop coils LCx) of loop coils LCx as selection targets (step S43).

[0193] Next, the sensor controller 31 selects the loop coil at the end of the selected loop coil LCx and connects it to the operational amplifier 30e by controlling the switch 30b (step S41). In addition, the sensor controller 31 selects six linear electrodes EL from the end of the selected linear electrodes EL and controls the switch 30f to connect the selected six linear electrodes EL in the first connection mode (for example, Figure 21 The device is connected to the driving circuit 30k (the connection method shown in FIG. 4 ) (step S45 ).

[0194] Transfer to Figure 27 Then, the sensor controller 31 performs Figure 25 and Figure 26 The same processing as steps S32 to S41 is performed (steps S46 to S55). However, the processing here differs from the processing of steps S32 to S41 in that, whereas in step S33, only the level of the reception signal Rx_EMR is temporarily stored, in step S47, a series of digital values ​​(digital values ​​obtained by sampling) constituting the reception signal Rx_EMR are also stored. In step S37, it is determined whether all linear electrodes EL have been selected, whereas in step S51, it is determined whether all linear electrodes EL determined as selection targets in step S43 have been selected. In step S39, it is determined whether all loop coils LCx have been selected, whereas in step S53, it is determined whether all loop coils LCx determined as selection targets in step S43 have been selected.

[0195] Having determined in step S55 that a pen signal has been detected, the sensor controller 31 derives the position of the electromagnetic induction pen P, obtains the data transmitted by the electromagnetic induction pen P, and outputs it to the main processor 32 (step S56). Specifically, the sensor controller 31 derives the position of the electromagnetic induction pen P based on the pen signal levels for each combination of the analog loop coil PLC and loop coil LCx derived in step S50. Furthermore, the sensor controller 31 demodulates the series of digital values ​​stored in step S47 for the combination of the analog loop coil PLC and loop coil LCx closest to the derived position, thereby obtaining the data transmitted by the electromagnetic induction pen P. After completing step S56, the sensor controller 31 returns to step S43 to continue processing.

[0196] The position detection method of this embodiment can also improve the S / N ratio of the pen signal received by the sensor controller 31 without reducing the frequency of position detection or increasing the circuit scale of the sensor controller 31. This effect will be described in detail below with reference to experimental results.

[0197] Figure 28 (a) to (c) represent Figure 24 In the connection methods (a) to (c), the electromagnetic induction pen P is located in the analog loop coil PLC m+1 In the case of the above, the reception signal Rx_EMR (-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 ) diagram. Figure 28 (d) to (f) respectively represent the Figure 28 In the case of the received signal Rx_EMR shown in (a) to (c), the level E of the pen signal obtained by the restoration operation shown in formula (20) is m、n 、E m+1、n 、E m+2、n Picture.

[0198] Compare Figure 28 (a) to (c) and Figure 28As can be seen from (d) to (e), the level of the pen signal after the restoration operation is 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 is tripled. Here, as described above, when the pen signal detection period of the pen signal in the sensor controller 31 is increased by N times, the level of the received pen signal is increased by N times, while the level of the received noise remains at N. 1 / 2 Therefore, it can be said that the position detection system 1 according to this embodiment can also 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.

[0199] This effect is also achieved when the electromagnetic induction pen P is tilted. This point will be described below.

[0200] first, Figure 29 3 and 4 are diagrams for explaining angles θ and φ showing the inclination of the electromagnetic induction pen P. Figure 29 (a) shows angle θ. As shown in the figure, angle θ is the angle between the z direction (a direction perpendicular to the touch surface) and the pen axis. Angle θ is also called the "tilt angle." Figure 29 B shows an angle φ. As shown in the figure, the angle φ is the angle between the x direction, which is the extending direction of the loop coil LCy, and the pen axis.

[0201] Figures 30 to 33 The graphs show the pen signal levels obtained when (θ, φ) = (0, 0), (60, 0), (60, 90), and (60, 180). The horizontal axis of each graph represents the position in the y direction in millimeters. The 5mm-5mm, 0mm, and +5mm on the horizontal axis of each graph correspond to the analog loop coil PLC. m-1 、PLC m 、PLC m+1 In addition, Figure 30 and Figure 31 The vertical axis represents the level of the pen signal in arbitrary units (au) (the level after restoration operation in the case of restoration operation). Figure 32 The vertical axis of represents the value obtained by normalizing the level of the pen signal by setting the maximum value to 1 in arbitrary units.

[0202] Curve A m-1 、A m and A m+1 y-axis and y-axis represent the level of the pen signal at each position acquired by the sensor controller 31 according to the present embodiment when the position of the electromagnetic induction pen P in the y direction is -5, 0, and +5, respectively. mAs a comparative example of this embodiment, a circuit is shown in which only one analog loop coil PLC is used. m When an alternating magnetic field is sent (i.e., only to the linear electrode EL m EL m+3 The level of the pen signal at each position obtained by the sensor controller 31) when AC current is supplied.

[0203] First, refer to Figures 30 to 33 As can be seen from each (a), the maximum value of the pen signal level obtained by the sensor controller 31 of this embodiment is a value equal to or greater than (θ, φ) = (0, 0) even when the angle θ is not 0. The maximum value of the pen signal level when the angle θ = 60° exceeds the value when the angle θ = 0° because the larger the angle θ, the smaller the distance between the coil in the electromagnetic induction pen P and the touch surface. In addition, referring to Figures 30 to 33 As shown in (b), the ratio of the pen signal level obtained by sensor controller 31 in this embodiment to the pen signal level obtained by sensor controller 31 in the comparative example is at least as high as (θ, φ) = (0, 0) even when angles θ and φ are not zero. Therefore, the position detection method of this embodiment can improve the S / N ratio of the pen signal received by sensor controller 31, regardless of the values ​​of angles θ and φ.

[0204] Next, refer to Figures 30 to 33 As shown in (c), the distribution of the pen signal levels obtained by the sensor controller 31 of this embodiment has approximately the same shape as the distribution of the pen signal levels obtained by the sensor controller 31 of the comparative example. Therefore, it can be said that the position detection method of this embodiment does not cause errors in the position detection results.

[0205] As described above, according to the position detection method of this embodiment, it can be said that even when the electromagnetic induction pen P is tilted, the S / N ratio of the pen signal received in the sensor controller 31 can be improved without reducing the frequency of position detection and without increasing the circuit scale of the sensor controller 31.

[0206] Next, a description will be given of a position detection system 1 according to a fourth embodiment of the present invention. This embodiment differs from the position detection system 1 according to the third embodiment in the method for selecting the linear electrodes EL that simultaneously generate alternating current. In other respects, the position detection system 1 according to this embodiment is identical to the position detection system 1 according to the third embodiment, so the following description will focus on the differences from the position detection system 1 according to the third embodiment.

[0207] Figure 34(a) is a diagram illustrating a method of selecting the linear electrodes EL in the position detection system 1 according to the third embodiment. Figure 34 (b) is a diagram illustrating the method for selecting the linear electrode EL in the position detection system 1 of this embodiment. In these diagrams, a single quadrilateral represents a single linear electrode EL, and two linear electrodes EL connected by a thick dashed line with black circles at both ends correspond to a single analog loop coil PLC. If the distance between the two linear electrodes EL constituting a single analog loop coil PLC is referred to as the sensor space SP, then SP = 2 in both the third embodiment and the present embodiment. Furthermore, if the distance between adjacent analog loop coils PLC is referred to as the minimum pitch P, then min , then in the third embodiment P min =1, in this embodiment, P min =2. min =1, if Figure 34 As shown in (a), the linear electrodes EL that do not constitute the pseudo loop coil PLC are not arranged between the linear electrodes EL that constitute the pseudo loop coil PLC. min =2, if Figure 34 As shown in (b), a linear electrode EL that does not constitute the pseudo loop coil PLC is arranged between the plurality of linear electrodes EL that constitute the pseudo loop coil PLC (for example, between Figure 34 In the left diagram of (b), the second linear electrode EL from the top and the third linear electrode EL from the bottom).

[0208] If P is used as in the third embodiment min =1 (minimum value), the maximum number of pseudo loop coils PLC that can be formed simultaneously is 3. This is because if a fourth pseudo loop coil PLC is to be formed, the same linear electrode EL is used in two pseudo loop coils PLC. In contrast, if P is used as in the fourth embodiment, min = 2 (minimum value + 1), there is no limit to the number of pseudo loop coils PLC that can be formed simultaneously. Thus, when there is no limit to the number of pseudo loop coils PLC that can be formed simultaneously, the level of the pen signal obtained through the restoration operation can be improved. This point will be explained below.

[0209] First, in the following description, the method of detecting the received signal Rx_EMR by simultaneously forming n pseudo loop coils PLC will be referred to as "CDMn." "CDM" stands for "Code Division Multiplexing," and n represents the CDM degree. When using CDMn, alternating magnetic fields are transmitted from n pseudo loop coils PLC in n polarity patterns. The resulting n reception results are multiplied by an n×n matrix. This allows the voltage level of each pseudo loop coil PLC to be restored, similar to the third embodiment.

[0210] Figure 34 (a) indicates an example of "CDM3", Figure 34 (b) shows an example of "CDM7". As mentioned above, in P min = 1, the maximum number of simulated loop coils PLC that can be formed at the same time is 3, so Figure 34 (a) shows the case where the number n is the maximum value that can be taken. On the other hand, in P min = 2, there is no limit to the number of pseudo loop coils PLC that can be formed simultaneously, so more than 2 can be used depending on the total number of linear electrodes EL. Figure 34 The case of n=7 shown in (b) is a higher degree n.

[0211] Figure 35 (a), (b), and (c) are diagrams showing methods of selecting the linear electrodes EL in CDM1, CDM3, and CDM7, respectively. Figure 35 (d), (e), and (f) are diagrams showing the levels of pen signals obtained by CDM1, CDM3, and CDM7 (the levels after restoration operation when restoration operation is performed). In these diagrams, the pitch of the linear electrodes EL is set to 5 mm. Figure 35 (e) and (f) show the levels of pen signals at the linear electrodes EL when the electromagnetic induction pen P is located at the center of each pseudo loop coil PLC.

[0212] also, Figure 36 (a) and (b) are graphs showing the levels of pen signals obtained when CDM1, CDM3, and CDM7 are used, respectively. Figure 36 The vertical axis of (a) represents the level of the pen signal in arbitrary units (au) (the level after the restoration operation when the restoration operation is performed). Figure 36 The vertical axis of (b) shows the value obtained by normalizing the level of the pen signal by setting the maximum value to 1 in arbitrary units. Figure 36 (c) is a graph in which measured values ​​and theoretical values ​​are plotted for the peak values ​​of the pen signal levels in each of CDM1 , CDM3 , and CDM7 .

[0213] from Figure 35 Comparison of (d) (e) (f) and Figure 36 From the results of (a) and (c), it can be seen that the higher the number n of CDM is, the higher the level of the pen signal is. Figure 36 As shown in (b), the distribution of the pen signal level is substantially the same in CDM1, CDM3, and CDM7. Therefore, it can be said that by adopting P as in this embodiment, min =2 (minimum value+1), and performing CDM at a higher number than n=3, it is possible to achieve equivalent detection of the position of the electromagnetic induction pen P compared to the third embodiment, and to improve the level of the pen signal obtained by the restoration operation.

[0214] Figures 37 to 40 It is about P min =2 is the case of receiving the pen signal based on CDM3, and Figures 30 to 33 Similarly, the graph shows the pen signal levels for the cases where (θ, φ) = (0, 0), (60, 0), (60, 90), and (60, 180). Figures 37 to 40 and Figures 30 to 33 It can be seen that the distribution and value of the level of the received pen signal are in P min =2 and P min = 1. Therefore, it can be said that even when the angles θ and θ are taken into consideration, the position detection system 1 of this embodiment can be used to detect the position of the electromagnetic induction pen P in the same manner as the position detection system 1 of the third embodiment.

[0215] While preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments and can, of course, be implemented in various forms without departing from the spirit and scope of the present invention.

[0216] For example, in the third and fourth embodiments, when detecting the position of the electromagnetic induction pen P, the other end of each linear electrode EL in the x direction is grounded, and a current i is supplied to one end of two linear electrodes EL constituting the analog loop coil PLC. A , supply current i to the other end B , this is an example of sending an alternating magnetic field from the analog loop coil PLC, but an alternating magnetic field can also be sent from the analog loop coil PLC by other methods.

[0217] Figure 41 (a), (b), and (c) are diagrams showing how an alternating magnetic field is sent from a pseudo loop coil PLC using different methods. Figure 41 (d) (e) (f) respectively represent the Figure 41(a), (b), and (c) are diagrams showing the level of the pen signal obtained when an alternating magnetic field is sent from a PLC analog loop coil.

[0218] exist Figure 41 In (a), similar to the third and fourth embodiments, when detecting the position of the electromagnetic induction pen P, the other end of each linear electrode EL in the x direction is grounded, and a current i is supplied to one end of two linear electrodes EL constituting the analog loop coil PLC. A , supply current i to the other end B On the other hand, in Figure 41 (b) shows a method in which the other ends of the linear electrodes EL in the x direction are connected to each other when detecting the position of the electromagnetic induction pen P, and a current i is supplied to one end of two linear electrodes EL constituting the analog loop coil PLC. A , supply current i to the other end B In addition, Figure 41 (c) shows a method in which the other ends of the two linear electrodes EL constituting the analog loop coil PLC are connected to each other, and a current i is supplied to one end of the two linear electrodes EL. A , supply current i to the other end B .

[0219] If compared with each other Figure 41 As can be understood from (d), (e), and (f), the level and distribution of the pen signal are roughly the same in either CDM1 or CDM3k. Therefore, even if Figure 41 The position of the electromagnetic induction pen P can also be detected by sending an alternating magnetic field from the analog loop coil PLC using any of the methods (a), (b), and (c). Figure 41 The method shown in (c) is not suitable for the impedance of the linear electrode EL because a phase shift occurs if the impedance of the linear electrode EL is high. Figure 41 In the methods shown in (a) and (b), such a phase shift problem does not occur.

[0220] Furthermore, in the fourth embodiment described above, the cases where the number n of CDM is 1, 3, and 7 are described, but the number n of CDM may be 1 or greater.

[0221] [Explanation of Reference Numerals]

[0222] 1. Position detection system

[0223] 3 Position detection device

[0224] 30 switch part

[0225] 30a, 30b, 30f to 30j switches

[0226] 30c, 30k drive circuit

[0227] 30d wiring department

[0228] 30e, 30m operational amplifiers

[0229] 31 sensor controller

[0230] 32 main processors

[0231] EL linear electrode

[0232] F finger

[0233] L1 and L2 wiring

[0234] LCx, LCy loop coils

[0235] P electromagnetic induction pen

[0236] Analog loop coil

[0237] Rx, Rx_EMR, Rx_TP receive signals

[0238] T1~T3 pen signal detection period

[0239] Tx, Tx_EMR AC current

[0240] Tx_TP touch detection signal

[0241] Tx_TP part touch detection signal

[0242] i A , i B Alternating current.

Claims

1. A position detection method comprising the following steps: During a first period, a plurality of transmitting coil conductors arranged in parallel are connected to a drive circuit in a first connection manner, and a detection coil is used to detect an alternating magnetic field generated by a pointer in response to an alternating magnetic field simultaneously transmitted from the plurality of transmitting coil conductors by an alternating current supplied from the drive circuit, thereby obtaining a first result. During a second period different from the first period, the plurality of transmitting coil conductors are connected to the drive circuit in a second connection manner different from the first connection manner, and a detection coil is used to detect an alternating magnetic field generated by the pointer in response to an alternating magnetic field simultaneously transmitted from the plurality of transmitting coil conductors by an alternating current supplied from the drive circuit, thereby obtaining a second result; and The position of the indicator is derived based on the first result and the second result.

2. The position detection method according to claim 1, The first connection mode and the second connection mode have a relationship in which a plurality of vectors representing the connection states of the respective transmission coil conductors are linearly independent of each other.

3. The position detection method according to claim 1, The first connection method and the second connection method are determined based on a matrix having a rank equal to the number of the transmission coil conductors that simultaneously transmit an alternating magnetic field.

4. The position detection method according to claim 1, In the step of deriving the position of the indicator, the position of the indicator in the direction in which the transmitting coil conductors are arranged is derived based on the first result and the second result.

5. The position detection method according to claim 1, Each of the plurality of transmitting coil conductors is formed of two linear electrodes through which currents having time differentials opposite to each other flow.

6. The position detection method according to claim 5, The current flowing through one of the two linear electrodes and the current flowing through the other have different signs from each other.

7. The position detection method according to claim 5, The current flowing through one of the two linear electrodes and the current flowing through the other linear electrode have the same sign and are different in level from each other.

8. The position detection method according to claim 1, The plurality of linear electrodes constituting the plurality of transmitting coil conductors are part of a plurality of linear electrodes arranged in a row, and the linear electrodes not constituting the plurality of transmitting coil conductors are not arranged between the plurality of linear electrodes constituting the plurality of transmitting coil conductors.

9. The position detection method according to claim 1, The plurality of linear electrodes constituting the plurality of transmitting coil conductors are part of a plurality of linear electrodes arranged in a row, and the linear electrodes not constituting the plurality of transmitting coil conductors are arranged between the plurality of linear electrodes constituting the plurality of transmitting coil conductors.

10. The position detection method according to claim 1, The plurality of transmitting coil conductors are each formed of a toroidal coil.

11. The position detection method according to claim 9, The two loop coils respectively constituting two adjacent transmitting coil conductors are arranged to overlap each other.

12. The position detection method according to claim 1, The method further includes the steps of connecting the plurality of transmitting coil conductors to the drive circuit in a third connection mode that is different from both the first connection mode and the second connection mode, and detecting, using a detection coil, an alternating magnetic field generated by the indicator based on the alternating magnetic field simultaneously transmitted from the plurality of transmitting coil conductors by the alternating current supplied from the drive circuit, thereby obtaining a third result. In the step of deriving the position of the indicator, the position of the indicator is derived based on the first result, the second result, and the third result.

13. An integrated circuit connected to a plurality of transmitting coil conductors, a driving circuit, and a detecting coil arranged in parallel, for deriving the position of a pointer, wherein: During a first period, the plurality of transmitting coil conductors are connected to the drive circuit in a first connection manner, and the detection coil is used to detect an alternating magnetic field generated by a pointer in response to an alternating magnetic field simultaneously transmitted from the plurality of transmitting coil conductors by an alternating current supplied from the drive circuit, thereby obtaining a first result. During a second period different from the first period, the plurality of transmitting coil conductors are connected to the drive circuit in a second connection manner different from the first connection manner, and the detection coil is used to detect an alternating magnetic field generated by the indicator in response to an alternating magnetic field simultaneously transmitted from the plurality of transmitting coil conductors by an alternating current supplied from the drive circuit, thereby obtaining a second result. The position of the indicator is derived based on the first result and the second result.

14. A sensor device for deriving a position of an indicator, wherein: have: a plurality of transmitting coil conductors arranged in parallel; Drive circuit; a detection coil; and The integrated circuit is connected to a plurality of transmitting coil conductors, a driving circuit and a detecting coil arranged in parallel. During a first period, the integrated circuit connects the plurality of transmitting coil conductors to the drive circuit in a first connection manner, and uses the detection coil to detect an alternating magnetic field generated by a pointer based on an alternating magnetic field simultaneously transmitted from the plurality of transmitting coil conductors by an alternating current supplied from the drive circuit, thereby obtaining a first result. The integrated circuit connects the plurality of transmitting coil conductors to the drive circuit in a second connection method different from the first connection method during a second period different from the first period, and uses the detection coil to detect an alternating magnetic field generated by the indicator based on the alternating magnetic field simultaneously transmitted from the plurality of transmitting coil conductors by the alternating current supplied from the drive circuit, thereby obtaining a second result. The integrated circuit derives the position of the indicator based on the first result and the second result.

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