SENSOR DEVICE, INTEGRATED CIRCUIT AND METHOD FOR DETECTING AN INDICATOR

Abstract

[Task] Prevent an increase in power consumption, even when linear electrodes replace Tx coils. [Solution] A sensor device comprises: a linear electrode group EL extending parallel; a loop coil group LCx crossing the linear electrode group EL; and a sensor control unit 31.The sensor control unit 31 is configured to sequentially export alternating magnetic fields from the linear electrode group EL, to use the loop coil group LCx to detect an alternating magnetic field generated by an indicator according to the alternating magnetic fields, to determine a linear electrode set containing a part of the linear electrode group EL based on a detection result, to execute a process for generating alternating magnetic fields in at least one part of the linear electrode set several times, to use several result values ​​detected by at least the part of the loop coil group LCx as a result of the execution to derive a two-dimensional position of the indicator, and to update the linear electrode set according to the derived two-dimensional position.

Description

Technical area

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

[0002] An electromagnetic resonance (EMR) system is known as a system for detecting the position of an electromagnetic resonance stylus in a screen surface of a tablet terminal or the like. The tablet terminal of the EMR system includes a sensor (hereinafter referred to as an "EMR sensor") for detecting the stylus disposed in the screen surface, and a sensor control unit connected to the EMR sensor. The EMR sensor includes a plurality of Tx coils arrayed and arranged in a y-direction and a plurality of Rx coils arrayed and arranged in an x-direction. The sensor control unit sequentially outputs alternating magnetic fields from the plurality of Tx coils, and each Rx coil receives a reflection signal (hereinafter referred to as a "stylus signal") transmitted from the electromagnetic resonance stylus.In this way, the sensor control unit detects the position of the electromagnetic resonance pin and receives data transmitted from the electromagnetic resonance pin.

[0003] An example of the EMR sensor is disclosed in Patent Literature 1. In the EMR sensor described in Patent Literature 1, drive electrodes in a display device (linear electrodes to which drive signals are supplied for display) are used as Tx coils, and signal lines in the display device (wires to which image signals are supplied) are used as Rx coils to suppress a price increase. Generation of alternating magnetic fields by the drive electrodes is performed using a selection signal to select two drive electrodes, wherein a current is applied from one end to another end of one of the drive electrodes, and the same current is applied from another end to another end of the other drive electrode. In Patent Literature 1, the drive electrodes and the signal lines in the display device are also used as touch electrodes for detecting a finger through a capacitance system. State-of-the-art documentPatent document

[0004] Patent Literature 1: Japanese Patent No. 6698386 SUMMARY OF THE INVENTIONTechnical Problem

[0005] Incidentally, a current with a larger amplitude than a drive signal for display or the like must be applied to the EMR sensor's Tx coil to generate a magnetic field of the required magnitude. When such a large current is applied to the linear electrode that replaces the Tx coil, power consumption increases because the direct current (DC) resistance of the linear electrode is larger than that of the general Tx coil. Therefore, a technique that can prevent this increase in power consumption is needed even when the linear electrodes replace the Tx coils.

[0006] Therefore, an object of the present invention is to provide a sensor device that can prevent an increase in power consumption even when linear electrodes replace Tx coils.

[0007] In addition, when alternating magnetic fields are generated using the selection signal to select two linear electrodes, where the current is applied from one end to the other end of one of the linear electrodes and the same current is applied from the other end to one end of the other linear electrode, as in the invention described in Patent Literature 1, a phase shift occurs between the two linear electrodes. As a result, noise is superimposed on the magnetic field detected by the Rx coil, and improvement is necessary.

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

[0009] One aspect of the present invention provides a sensor device that detects an indicator, the sensor device including a linear electrode group extending in parallel, a detection coil group crossing the linear electrode group, and an integrated circuit connected to the linear electrode group and the detection coil group, in which the integrated circuit is configured to sequentially export alternating magnetic fields from the linear electrode group, use the detection coil group to detect an alternating magnetic field generated by the indicator according to the alternating magnetic fields, and determine a linear electrode set including part of the linear electrode group based on the detection result, execute a process for exporting alternating magnetic fields from at least part of the linear electrode set a plurality of times, and generate a plurality of result values,which are detected by at least part of the detection coil group, as a result of the execution to derive a two-dimensional position of the indicator, and to update the linear electrode set according to the derived two-dimensional position.,

[0010] The aspect of the present invention provides an integrated circuit connected to a linear electrode group extending in parallel and a detection coil group crossing the linear electrode group, the integrated circuit being configured to detect an indicator, the integrated circuit being further configured to sequentially export alternating magnetic fields from the linear electrode group, use the detection coil group to detect an alternating magnetic field generated by the indicator according to the alternating magnetic fields, and determine a linear electrode set including a part of the linear electrode group based on a detection result, execute a process for exporting alternating magnetic fields from at least a part of the linear electrode set a plurality of times, and generate a plurality of result values,which are detected by at least part of the detection coil group, as a result of the execution to derive a two-dimensional position of the indicator, and to update the linear electrode set according to the derived two-dimensional position.,

[0011] The aspect of the present invention provides a method for detecting an indicator using a linear electrode group extending in parallel and a detection coil group crossing the linear electrode group, the method comprising a step of exporting, in sequence, alternating magnetic fields from the linear electrode group, using the detection coil group to detect an alternating magnetic field generated by the indicator according to the alternating magnetic fields, and determining a linear electrode set including a part of the linear electrode group based on a detection result, a step of executing a process of exporting alternating magnetic fields from at least a part of the linear electrode set a plurality of times and using a plurality of result values ​​detected by at least a part of the detection coil group as a result of the execution,to derive a two-dimensional position of the indicator, and a step for updating the linear electrode set according to the derived two-dimensional position.,

[0012] Another aspect of the present invention provides a sensor device that detects an indicator, the sensor device including a linear electrode group extending in parallel, a detection coil group crossing the linear electrode group, and an integrated circuit connected to the linear electrode group and the detection coil group, in which the integrated circuit is configured to supply a first alternating current to one end in a longitudinal direction of one or more first linear electrodes in the linear electrode group and to supply a second alternating current to one end in the longitudinal direction of one or more second linear electrodes different from the first linear electrodes in the linear electrode group, and the first alternating current and the second alternating current are generated to satisfy a ratio,that phases of time derivatives of the first alternating current and the second alternating current are opposite.,

[0013] The other aspect of the present invention provides an integrated circuit connected to a linear electrode group extending in parallel and a detection coil group crossing the linear electrode group, the integrated circuit being configured to detect an indicator, the integrated circuit being further configured to supply a first alternating current to one end in a longitudinal direction of one or more first linear electrodes in the linear electrode group and supply a second alternating current to one end in the longitudinal direction of one or more second linear electrodes different from the one or more first linear electrodes in the linear electrode group, in which the first alternating current and the second alternating current are generated to satisfy a ratio,that phases of time derivatives of the first alternating current and the second alternating current are opposite.,

[0014] The other aspect of the present invention provides a method for detecting an indicator using a linear electrode group extending in parallel and a detection coil group crossing the linear electrode group, the method including a step of generating a first alternating current and a second alternating current such that a relationship is satisfied that phases of time derivatives of the first alternating current and the second alternating current are opposite, and a step of supplying the first alternating current to one end in a longitudinal direction of one or more first linear electrodes in the linear electrode group and supplying the second alternating current to one end in the longitudinal direction of one or more second linear electrodes different from the one or more first linear electrodes in the linear electrode group. Beneficial effects

[0015] According to the sensor device, integrated circuit, and indicator detection method of the present invention, once the linear electrode set is specified, the two-dimensional position of the indicator can be derived by supplying current to only the predetermined number of linear electrodes included in the linear electrode set. Therefore, the increase in power consumption can be prevented even when the linear electrodes replace the Tx coils.

[0016] According to the sensor device, integrated circuit, and indicator detection method of the other aspect of the present invention, the occurrence of phase shift between two linear electrodes can be prevented. Therefore, the noise superimposed on the magnetic fields detected by the Rx coils can be reduced when the linear electrodes replace the Tx coils. SHORT DESCRIPTION OF DRAWINGS [ Fig. 1] Fig. 1 is a diagram illustrating a configuration of a position detection system 1 according to a first embodiment of the present invention. [ Fig. 2] Fig. Fig. 2 is a diagram illustrating an internal configuration of a switching unit 30 used in Fig. 1 is illustrated. [ Fig. 3] Fig. 3 is a diagram illustrating a state of the switching unit 30 when a sensor control unit 31 detects the position of a finger F. [ Fig. 4] Fig. 4 is a diagram illustrating a state of the switching unit 30 when the sensor control unit 31 detects the position of an electromagnetic resonance pin P. [ Fig. 5] Fig. 5 is a diagram illustrating a state of the switching unit 30 when the sensor control unit 31 detects the position of the electromagnetic resonance pin P. [ Fig. 6] Fig. 6 is a diagram illustrating a state of the switching unit 30 when the sensor control unit 31 detects the position of the electromagnetic resonance pin P. [ Fig. 7] Fig. 7A is a diagram illustrating a method of supplying alternating currents to linear electrodes EL according to the present embodiment, and Fig. 7B is a diagram illustrating a method of supplying the alternating current according to a comparative example. [ Fig. 8] Fig. Fig. 8A is a diagram illustrating a result of measurement of the currents flowing through the linear electrodes EL in an examination region PA1 as shown in Fig. 7A illustrates, and Fig. Fig. 8B is a diagram illustrating a result of measuring the currents flowing through the linear electrodes EL in an examination region PA2 as shown in Fig. 7B illustrates. [ Fig. 9] Fig. 9A and Fig. 9B are diagrams in which results of measurement of a phase difference θ, an amplitude A and an amplitude B in the comparative example for a case of several different total parasitic capacitances are plotted. [ Fig. 10] Fig. 10A is a diagram illustrating waveforms of various signals relating to the present embodiment, and Fig. 10B is a diagram illustrating a method of supplying various signals related to the comparative example. [ Fig. 11] Fig. 11 is a diagram describing a reception signal Rx supplied from a differential amplifier 30i to the sensor control unit 31. [ Fig. 12] Fig. 12 is a diagram describing the reception signal Rx according to a first comparative example. [ Fig. 13] Fig. 13 is a diagram describing the reception signal Rx according to a second comparative example. [ Fig. 14] Fig. 14 is a diagram illustrating results of a simulation of levels of the pen signal generated by loop coils LCx near a loop coil LCx n is received when the electromagnetic resonance pin P on the loop coil LCx n is positioned. [ Fig. 15] Fig. 15 is a flowchart illustrating an entire flow of position detection of the electromagnetic resonance pin P executed by the sensor control unit 31. [ Fig. 16] Fig. Fig. 16 is a flowchart illustrating the entire procedure of position detection of the electromagnetic resonance pin P performed by the sensor control unit 31. [ Fig. 17] Fig. Fig. 17 is a flowchart illustrating the entire procedure of position detection of the electromagnetic resonance pin P performed by the sensor control unit 31. [ Fig. 18] Fig. 18 is a diagram illustrating an internal configuration of the switching unit 30 arranged in a position detection device 3 included in the position detection system 1 according to a second embodiment of the present invention. [ Fig. 19] Fig. 19 is a diagram illustrating a state of the switching unit 30 when the sensor control unit 31 detects the position of the electromagnetic resonance pin P. [ Fig. 20] Fig. 20 is a diagram illustrating a state of the switching unit 30 when the sensor control unit 31 detects the position of the electromagnetic resonance pin P. [ Fig. 21] Fig. 21 is a diagram illustrating a state of the switching unit 30 when the sensor control unit 31 detects the position of the electromagnetic resonance pin P. [ Fig. 22] Fig. 22 is a diagram illustrating an internal configuration of the switching unit 30 arranged in the position detection device 3 included in the position detection system 1 according to a third embodiment of the present invention. [ Fig. 23] Fig. 23 is a diagram illustrating a state of the switching unit 30 when the sensor control unit 31 detects the position of the electromagnetic resonance pin P. [ Fig. 24] Fig. 24 is a diagram illustrating a state of the switching unit 30 when the sensor control unit 31 detects the position of the electromagnetic resonance pin P. [ Fig. 25] Fig. 25 is a diagram illustrating a state of the switching unit 30 when the sensor control unit 31 detects the position of the electromagnetic resonance pin P. [ Fig. 26] Fig. 26(a) to 26(c) are diagrams schematically showing methods for supplying the alternating currents in Fig. 23 to 25 illustrate, and Fig. 26(d) to 26(f) are diagrams illustrating equivalent circuits when the methods described in Fig. 26(a) to 26(c), for supplying alternating currents i A and i B to six linear electrodes EL m to EL m+5 be used. [ Fig. 27] Fig. Fig. 27 is a flowchart illustrating an entire flow of position detection of the electromagnetic resonance pin P executed by the sensor control unit 31. [ Fig. 28] Fig. Fig. 28 is a flowchart illustrating the entire procedure of position detection of the electromagnetic resonance pin P performed by the sensor control unit 31. [ Fig. 29] Fig. Fig. 29 is a flowchart illustrating the entire procedure of position detection of the electromagnetic resonance pin P performed by the sensor control unit 31. MODES FOR CARRYING OUT THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0018] Fig. 1 is a diagram illustrating a configuration of a position detection system 1 according to a first embodiment of the present invention. As shown in Fig. 1, the position detection system 1 includes an electromagnetic resonance pin P and a position detection device 3. Of these, the electromagnetic resonance pin P is a pin (indicator) corresponding to a position detection based on the EMR system, and the electromagnetic resonance pin P includes a resonance circuit including a coil and a capacitor inside

[0019] The position detection device 3 is a device (sensor device) corresponding to the position detection of the electromagnetic resonance pen P based on the EMR system, and the position detection device 3 includes a plurality of loop coils LCx (detection coil group), a plurality of linear electrodes EL (linear electrode group), a switching unit 30, a sensor control unit 31, and a host processor 32. Although typical examples of the position detection device 3 include a tablet terminal and a laptop in which a display surface serves as the touch surface, the position detection device 3 may be a digitizer or the like that does not include the display surface.

[0020] The x- and y-directions shown are directions in the contact surface, and the x- and y-directions are orthogonal to each other. The plurality of loop coils LCx are formed to extend in the y-direction (first direction) and are lined up and arranged in the x-direction (second direction). On the other hand, the plurality of linear electrodes EL are formed to extend in the x-direction and are lined up and arranged in the y-direction. Each of the loop coils LCx and each of the linear electrodes EL is connected to the switching unit 30 at both ends.

[0021] The switching unit 30 is a set of switches that includes a plurality of switches for switching the mutual connections of the plurality of loop coils LCx and switching the connections between the plurality of loop coils LCx and the plurality of linear electrodes EL and the sensor control unit 31. The switching unit 30 may be provided in a dedicated printed circuit board or integrated circuit, or may be provided in the same integrated circuit as the sensor control unit 31. The switching state of the switching unit 30 is controlled by the sensor control unit 31.

[0022] Fig. Fig. 2 is a diagram illustrating an internal configuration of the switching unit 30. For the sake of simplicity, Fig. 2 only five loop coils LCx and five linear electrodes EL (loop coils LCx n-2 up to LCx n+2 and linear electrodes EL m-2 to EL m+2 ). This is also the case in Fig. 3 to 6 and Fig. 18 to 21, which will be described later. As in Fig. 2, the switching unit 30 includes five kinds of switches 30a to 30f, a driver circuit 30g, a wiring unit 30h, a differential amplifier 30i, and an operational amplifier 30j.

[0023] The switch 30a is configured to supply an alternating current Tx_EMR to a plurality of linear electrodes EL to generate an alternating magnetic field on the touch surface. The switch 30a includes four input pins connected to the driver circuit 30g and output pins corresponding to the linear electrodes EL. Each output pin is connected to one end of the corresponding linear electrode EL in the x-direction (longitudinal direction). The switch 30a plays a role in connecting each input pin to one of the output pins under the control of the sensor control unit 31.

[0024] The driver circuit 30g is a circuit that generates alternating currents i A and i B (see Fig. 4 to 6) according to the alternating current Tx_EMR supplied from the sensor control unit 31 and which contains the alternating currents i A and i B through the switch 30a to the linear electrodes EL. The driver circuit 30g is configured to supply the alternating current i A (first alternating current) to two of the four input pins of switch 30a and the alternating current i B (second alternating current) to the other two.

[0025] The alternating current i A For example, is a current generated using a buffer circuit to amplify the alternating current Tx_EMR. On the other hand, the alternating current i B a current that is generated to satisfy a relationship that the phases of the time derivatives of the alternating currents i A and i Bare opposite. The relationship can be expressed by a formula as in the following equation (1). It can be claimed that the relationship of equation (1) is a relationship that the alternating current i B with an increase in alternating current i A decreases and that the alternating current i B with a decrease in alternating current i A It can also be claimed that the relationship of equation (1) is a relationship that the potential at one end relative to the other end in the longitudinal direction of each of the one or more linear electrodes EL, which alternating current i B is supplied, with an increase in the potential at the other end relative to the one end in the longitudinal direction of each of the one or more linear electrodes EL, which alternating current i A is increasing. [Math. 1] diA(t)dt=−diB(t)dt

[0026] A typical alternating current i B , which satisfies the relationship of equation (1), is represented by the following equation (2). Here, A is an arbitrary constant. When A = 0, the alternating current i B an inverted signal of the alternating current i A In this case, the signs of the alternating current i A and the alternating current i B different. On the other hand, if A is greater than the maximum value of the alternating current i A is, the alternating current i A and the alternating current i B Currents with the same sign and different levels. Note that the reverse signal of the alternating current i A for example, using an inverting buffer circuit. Fig. 2 illustrates an example of using the inverting buffer circuit. [Math. 2] iB(t)=−iA(t)+A

[0027] It is preferred that the potential at the other end of each of the linear electrodes EL to which the alternating currents i A and i B a potential at the midpoint of the potential generated at one end of the linear electrode EL, to which the alternating current i A and the potential generated at one end of the linear electrode EL to which the alternating current i B is supplied. When A = 0, the potential is 0 (that is, ground potential).

[0028] The switch 30b 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. A set of one input pin and one output pin is provided for each linear electrode EL. The touch detection signal Tx_TP is supplied from the sensor control unit 31 to each input pin. Each output pin is connected to the corresponding linear electrode EL. The switch 30b plays a role in connecting each input pin to the corresponding output pin under the control of the sensor control unit 31.

[0029] The switch 30f is configured to switch between a state in which the other end of the linear electrode EL in the x-direction (longitudinal direction) is connected to the potential at the center point and a potential-free state in which the other end is not connected to anything. Fig. Figure 2 illustrates a case where the potential at the midpoint is the ground potential and a set of an input pin and a ground pin is provided for each linear electrode EL in this case in the switch 30f, as shown in Fig. 2. The following description continues based on the assumption that the potential at the center is the ground potential.

[0030] Each input pin of the switch 30f is connected to the other end of the corresponding linear electrode EL in the x-direction (longitudinal direction). On the other hand, each ground pin of the switch 30f is connected to a ground end to which the ground potential is supplied. The switch 30f is provided because, while it is preferable that the ground potential be supplied to the other end of each linear electrode EL in the x-direction as described above when the sensor control unit 31 detects the position of the electromagnetic resonance pin P, the other end of each linear electrode EL in the x-direction must be in a floating state when the sensor control unit 31 detects the position of the finger F. The switch 30f plays a role in switching the connection state between each input pin and the corresponding ground pin under the control of the sensor control unit 31.

[0031] The switches 30c to 30e and the wiring unit 30h are configured to supply a pin signal received from each loop coil LCx (signal indicated by the alternating magnetic field generated by the electromagnetic resonance pin P according to the alternating magnetic field generated by the alternating current Tx_EMR) to the differential amplifier 30i and supply the touch detection signal Tx_TP received from each loop coil LCx to the operational amplifier 30j.

[0032] Specifically, first, the switch 30c includes input pins corresponding to the end portions of the loop coils LCx, and four output pins are provided for each input pin. The switch 30c plays a role in connecting each input pin to one of the four corresponding output pins under the control of the sensor control unit 31.

[0033] The wiring unit 30h contains four wires L1 to L4. The four output pins for each input pin of the switch 30c correspond to the four wires L1 to L4, and the four output pins are each connected to the corresponding wires.

[0034] Switch 30d is a switch that connects wire L1 to a non-inverting input terminal of differential amplifier 30i and connects wire L2 to an inverting input terminal of differential amplifier 30i under the control of sensor control unit 31. Switch 30e is a switch that connects wire L4 to an input terminal of operational amplifier 30j under the control of sensor control unit 31. The initial state of switches 30d and 30e is off (unconnected state).

[0035] The differential amplifier 30i is a circuit that amplifies a voltage difference between the non-inverting input terminal connected to the wire L1 and the inverting input terminal connected to the wire L2 to generate a reception signal Rx_EMR. The differential amplifier 30i, together with the sensor control unit 31, forms a receiving circuit for the pin signal. In addition, the operational amplifier 30j is a circuit that amplifies a voltage difference between the input terminal and the ground terminal to generate a reception signal Rx_TP of the capacitance system. The operational amplifier 30j, together with the sensor control unit 31, forms a reception circuit for the touch detection signal Tx_TP.The input terminal of operational amplifier 30j is connected to wire L4 of wiring unit 30h through switch 30e, and consequently, the received signal Rx_TP is a signal obtained by amplifying the signal appearing in wire L4. Operational amplifier 30j is provided with a parallel capacitor for removing high-frequency noise. Both the received signal Rx_EMR generated by differential amplifier 30i and the received signal Rx_TP generated by operational amplifier 30j are fed to sensor control unit 31.

[0036] Fig. 1 will be described in more detail. The sensor control unit 31 is an integrated circuit having a function of using the EMR system to detect the position of the electromagnetic resonance stylus P in the touch surface and a function of using the capacitance system to detect the position of the finger F on the touch surface. In relation to the electromagnetic resonance stylus P, the sensor control unit 31 also has a function of demodulating the stylus signal transmitted from the electromagnetic resonance stylus P to collect the data transmitted from the electromagnetic resonance stylus P. The detection of the position of the electromagnetic resonance stylus P and the collection of the data from the electromagnetic resonance stylus P and the detection of the position of the finger F are performed in time series.The sensor control unit 31 is configured to transmit the detected position and the collected data sequentially to the host processor 32.

[0037] The host processor 32 uses the position and data supplied from the sensor control unit 31 to execute processes such as moving the cursor displayed on the display surface and generating stroke data indicating the trajectory of the electromagnetic resonance pen P or the finger in the touch surface. Of these, with respect to the stroke data, the host processor 32 also executes a process for reproducing and displaying the generated stroke data, a process for generating and recording digital ink containing the generated stroke data, a process for transferring the generated digital ink to an external device according to the user's instruction, and the like.

[0038] Hereinafter, the processes for detecting the positions of the electromagnetic resonance pen P and the finger F, which are carried out by the sensor control unit 31, will be described in more detail with reference to Fig. 3 to 6.

[0039] First of all, Fig. 3 is a diagram illustrating a state of the switching unit 30 when the sensor control unit 31 according to the present embodiment detects the position of the finger F. As in Fig. As illustrated in Figure 3, in this case, the sensor control unit 31 controls the switch 30b to connect the input pins and the corresponding output pins. As a result, the touch detection signal Tx_TP from the sensor control unit 31 is supplied to one end of each linear electrode EL in the x-direction. Additionally, the sensor control unit 31 controls the switch 30f to disconnect the input pins from the corresponding ground pins to place the other end of each linear electrode EL in the x-direction in the floating state.

[0040] The exact content of the touch detection signal Tx_TP generated by the sensor control unit 31 can be represented by a matrix A, which is illustrated in the following equation (3). The matrix A is a square matrix containing several rows that correspond one-to-one to the plurality of linear electrodes EL. The left side of a subscript character assigned to each element (such as A11 ) added to the matrix A indicates the order of output from the sensor control unit 31, and the right side indicates a serial number of the linear electrode EL. M is a total number of the linear electrodes EL. A specific value of each element is either "1" or "-1." Although it is preferable that the matrix A be an orthogonal matrix, the matrix A may not be an orthogonal matrix. [Math. 3] A=(A11A21A31⋯AM1A12A22A32⋯AM2A13A23A33⋯AM3 ⋮ ⋮⋮⋯ ⋮A1MA2MA3M⋯AMM)

[0041] The sensor control unit 31 generates the touch detection signal Tx_TP for each column of the matrix A and supplies the touch detection signal Tx_TP to each linear electrode EL. The touch detection signal Tx_TP is, in a typical example, a binary pulse signal that is high when the corresponding element of the matrix A is 1 and low when the element 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."

[0042] While the sensor control unit 31 supplies a partial touch detection signal Tx_TP to each linear electrode EL, the sensor control unit 31 maintains the switch 30e in the connected state and performs a process of sequentially connecting the loop coils LCx to the operational amplifier 30j. Specifically, the sensor control unit 31 controls the switch 30c to sequentially connect the loop coils LCx to the wire L4 at both ends. Note that Fig. 3 illustrates an example of a case where the loop coil LCx n connected to wire L4.

[0043] Here, the capacitance between an m-th linear electrode EL m and an n-th loop coil LCx n is formed by C mn shown. When the partial touch detection signal Tx_TP corresponding to the x-th column of the matrix A is applied to each linear electrode EL and the n-th loop coil LCxn connected to the operational amplifier 30j, the reception signal Rx_TP supplied from the operational amplifier 30j to the sensor control unit 31 has a value illustrated in the following equation (4). [Math. 4] (Ax1 Ax2 Ax3 ⋯ AxM)(C1nC2nC3n ⋮CMn)

[0044] Therefore, the received signal Rx_TP, as a whole, for the n-th loop coil LCx n is obtained while supplying the partial touch detection signal Tx_TP corresponding to each column of the matrix A, is represented by a vector b illustrated in the following equation (5). [Math. 5] b=A(C1nC2nC3n ⋮CMn)

[0045] The sensor control unit 31 performs a calculation on the vector b as illustrated on the left side of the following equation (6) to determine the capacitance C mneach linear electrode EL. Here is a matrix A -1 , which is illustrated in equation (6), is an inverse matrix of the matrix A. As also illustrated in equation (6), an identity matrix I is obtained by multiplying the matrix A with the matrix A -1 Therefore, the sensor control unit 31 can perform the calculation to determine the capacitance C mn at the intersection point of the n-th loop coil LCx n and each linear electrode EL m to separate and collect, as illustrated on the right side of equation (6). [Math. 6] A−1b=A−1A(C1nC2nC3n ⋮CMn)=I(C1nC2nC3n ⋮CMn)=(C1nC2nC3n ⋮CMn)

[0046] The sensor control unit 31 performs a calculation similar to equation (6) on each loop coil LCx to determine the capacitance C mnat each intersection point of the linear electrode EL and the loop coil LCx. The sensor control unit 31 then derives the position (two-dimensional position) of the finger F based on the distribution of the derived capacitance C mn in the touch area. In particular, the sensor control unit 31 can derive the position corresponding to the peak of the distribution as the position of the finger F.

[0047] Afterwards Fig. 4 to 6 are diagrams illustrating a state of the switching unit 30 when the sensor control unit 31 detects the position of the electromagnetic resonance pin P. As in Fig. 4 to 6, the sensor control unit 31 controls the switch 30a to switch the alternating current i A to two linear electrodes EL m-1 and EL m-2 (first linear electrodes) that are located next to each other on one side and to conduct the alternating current i Bto two linear electrodes EL m+1 and EL m+2 (second linear electrodes), which are located next to each other on the other side, via a linear electrode EL m In addition, the sensor control unit 31 controls the switch 30f to connect each input pin to the corresponding ground pin to bring the other end of each linear electrode EL in the x-direction into the grounded state.

[0048] As a result of the control, a pseudo coil is formed around the linear electrode EL m formed and an alternating magnetic field is generated on the contact surface (especially above the linear electrode EL m ). In the following, the generation of the alternating magnetic field is referred to as “export of the alternating magnetic field from the linear electrode EL m The sensor control unit 31 is configured as the linear electrode EL mthe linear electrodes EL exclusively four linear electrodes EL positioned at both ends of the entire linear electrodes EL, to set in sequence and perform a similar process to thereby export similar alternating magnetic fields in sequence from the linear electrodes EL.

[0049] It should be noted that it is preferable to arrange the four linear electrodes EL, which are excluded from the execution of the process, at positions outside the touch surface so that the position detection of the electromagnetic resonance pin P can be performed on the entire touch surface. In addition, although the alternating currents are applied to two linear electrodes EL on both sides of the linear electrodes EL mTo apply alternating currents to the alternating currents from which the alternating magnetic fields are exported in the present embodiment, it is only necessary to apply the alternating currents to one or more of a predetermined number of linear electrodes EL on each side. For example, the alternating currents may be applied to one linear electrode EL on both sides, or may be applied to three or more linear electrodes EL on both sides.

[0050] As can be seen from the description of Fig. 4 to 6, the driver circuit is arranged on one end face of the linear electrodes EL in the longitudinal direction and both alternating currents i A and i B are supplied to one end (end portions of the same side) of the linear electrodes EL in the x-direction (longitudinal direction). In the following, an advantageous effect obtained by adopting the configuration will be described in detail, also with reference to a comparative example.

[0051] Fig. Fig. 7A is a diagram illustrating the method of supplying the alternating currents to the linear electrodes EL in the present embodiment, and Fig. Figure 7B is a diagram illustrating a method for supplying alternating currents in a comparative example. First, as shown in Fig. As illustrated in Fig. 7A, in the present embodiment, the alternating current i A one end of the linear electrodes EL m-1 and EL m-2 in the longitudinal direction and the alternating current i B is applied to one end of the linear electrodes EL m+1 and EL m+2 in the longitudinal direction. On the other hand, in the comparison example, the alternating current i A one end of the linear electrodes EL m-1 and EL m-2 in the longitudinal direction and the alternating current i A is applied to the other ends of the linear electrodes EL m+1 and EL m+2in the longitudinal direction, as in Fig. 7B. The method for supplying the alternating currents illustrated in the comparative example is described, for example, in Patent Literature 1.

[0052] Fig. Fig. 8A is a diagram illustrating a result of measurement of the currents flowing through the linear electrodes EL in an examination region PA1 as shown in Fig. 7A illustrates, and Fig. Fig. 8B is a diagram illustrating a result of measuring the currents flowing through the linear electrodes EL in an examination region PA2 as shown in Fig. 7B. In Fig. 8A and Fig. In Figure 8B, the horizontal axis represents time and the vertical axis represents current. Note that Fig. 8A and Fig. 8B, after reversing the current flowing through the linear electrodes EL m+1 and EL m+2is measured. Additionally, Fig. 8A and Fig. 8B shows a case where the parasitic capacitance (hereinafter referred to as “total parasitic capacitance”) of the current paths of the linear electrodes EL is 1800 pF.

[0053] The changing magnetic field can be most efficiently generated by the linear electrode EL m be exported if the amplitude (amplitude A, illustrated in Fig. 8B) of the current flowing through the linear electrodes EL m-1 and EL m-2 flows, equal to the amplitude (amplitude B, illustrated in Fig. 8B) of the current flowing through the linear electrodes EL m+1 and EL m+2 flows, and the phase difference (phase difference θ, illustrated in Fig. 8B) between the current flowing through the linear electrodes EL m-1 and EL m-2 and the reverse signal of the current flowing through the linear electrodes EL m+1 and EL m+2flows, is 0°. In this respect, as can be seen Fig. 8A, it can be claimed that the ideal state in terms of export efficiency of the alternating magnetic fields is achieved, since A = B and θ = 0° hold in the present embodiment. On the other hand, as shown in Fig. 8B, A ≠ B and θ ≠ 0° (specifically, approximately 32°) hold in the comparative example. Therefore, it can be claimed that the alternating magnetic fields from the linear electrodes EL m can be exported more efficiently in the present embodiment than in the comparative example.

[0054] Fig. 9A and Fig. 9B are diagrams in which the results of measuring the phase difference θ, the amplitude A and the amplitude B in the comparison example for a case of several different total parasitic capacitances are plotted. The horizontal axis of Fig. 9A and Fig. 9B indicates the total parasitic capacitance. The vertical axis of Fig. 9A indicates the phase difference θ and the vertical axis of Fig. 9B gives numerical values ​​that express amplitude B / amplitude A in percent. As can be seen from Fig. 9A and Fig. As can be seen from Figure 9B, the larger the total parasitic capacitance, the further the comparative example is shifted from the ideal state. Therefore, it can be claimed that the current paths must be designed to reduce the total parasitic capacitance when adopting the comparative example. On the other hand, the ideal state can be achieved as shown in Fig. 8A can be obtained in the present embodiment regardless of the total parasitic capacitance, and there is no particular need to design the current paths to reduce the total parasitic capacitance. Therefore, according to the present embodiment, an advantageous effect for facilitating circuit design can also be obtained compared to the comparative example.

[0055] Fig. 10A is a diagram illustrating waveforms of various signals relating to the present embodiment, and Fig. 10B is a diagram illustrating a method of supplying various signals related to the comparative example. Fig. 10A and Fig. 10B illustrate a waveform of the current flowing through the linear electrodes EL m-1 and EL m-2 flows, a waveform of the current flowing through the linear electrodes EL m+1 and EL m+2flows, a waveform (resonant pin waveform) of the voltage (pin signal) generated inside the electromagnetic resonance pin P, and a waveform of the reception signal Rx_EMR detected by the loop coil LCx closest to the electromagnetic resonance pin P.

[0056] First of all, Fig. 10B shows that while the sensor control unit 31 supplies the alternating current i A to the linear electrode EL (illustrated as the "export period of the alternating magnetic field"), the pen signal is generated inside the electromagnetic resonance pen P and a waveform similar to the alternating current i A, which is generated in the linear electrode EL, appears in the received signal Rx_EMR. The waveform of the received signal Rx_EMR is generated by superimposing a voltage signal induced in the loop coil LCx by the alternating magnetic field exported from the linear electrode EL on a voltage signal induced in the loop coil LCx by the pin signal exported from the electromagnetic resonance pin P. When the sensor control unit 31 supplies the alternating current i Ato the linear electrode EL, the part corresponding to the voltage signal induced by the alternating magnetic field exported by the linear electrode EL disappears, and only the part corresponding to the voltage signal induced by the pin signal remains in the received signal Rx_EMR. Although difficult to recognize due to scaling, the waveform of the received signal Rx_EMR after the end of the alternating current supply i Ato the linear electrode EL, a waveform similar to the waveform of the stylus signal is output. Therefore, the period after the "alternating magnetic field export period" is set as a "position derivation and data reception period" for deriving the position of the electromagnetic resonance stylus P and receiving the data transmitted from the electromagnetic resonance stylus P. The sensor control unit 31 according to the comparative example derives the position of the electromagnetic resonance stylus P and receives the data transmitted from the electromagnetic resonance stylus P based on the reception signal Rx_EMR acquired in the period.

[0057] On the other hand, the waveform of the received signal Rx_EMR in Fig. 10A shows a waveform similar to the pen signal during the entire period that includes the export period of the alternating magnetic field. The reason is that, as in Fig. 8A illustrates that there is no phase shift between the current flowing through the linear electrodes EL m-1 and EL m-2 and the current flowing through the linear electrodes EL m+1 and EL m+2flows. The currents cancel each other out, and the voltage signal induced in the loop coil LCx by the alternating magnetic field exported from the linear electrode ELm is not superimposed on the received signal Rx_EMR. That is, it can be said that the present embodiment achieves the reduction in noise superimposed on the alternating magnetic field detected by the loop coil LCx. The sensor control unit 31 according to the present embodiment utilizes this advantageous effect to use the "export period of the alternating magnetic field" also as a "position derivation period" for deriving the position of the electromagnetic resonance pin P, and derives the position of the electromagnetic resonance pin P based on the voltage signal appearing at the loop coil LCx in the period.Therefore, according to the present embodiment, a longer period for receiving the pin signal for deriving the position of the electromagnetic resonance pin P can be reserved compared to the comparative example, and the position of the electromagnetic resonance pin P can be derived with higher accuracy than in the comparative example.

[0058] Note that the reason why the sensor control unit 31 according to the present embodiment does not receive the data transmitted from the electromagnetic resonance pen P in the "alternating magnetic field export period" is because the electromagnetic resonance pen P cannot transmit data in the "alternating magnetic field export period." Specifically, the electromagnetic resonance pen P is configured to change the resonance frequency of the resonance circuit in the electromagnetic resonance pen P according to the content of the data to be transmitted, and to modulate the frequency of the pen signal based on the resonance frequency, thereby transmitting the data. When a alternating magnetic field from the position detection device 3 is present, the frequency of the pen signal is fixed to the frequency of the alternating magnetic field.Even if the resonance frequency of the resonance circuit in the electromagnetic resonance pen P is changed, the change is not reflected in the frequency of the pen signal. Therefore, the electromagnetic resonance pen P cannot transmit data during the "export period of the changing magnetic field."

[0059] Fig. 4 to 6 are described in more detail. While the sensor control unit 31 detects the alternating magnetic field from the linear electrode EL mexported, the sensor control unit 31 performs a process of keeping the switch 30d in the connection state, sequentially selecting sets of loop coils LCx, each set including three adjacent loop coils LCx, and controlling, whenever the set is selected, the switch 30c to connect the three loop coils LCx included in the selected set in series with the differential amplifier 30i in three connection modes with different connection polarities. As a result of the process, the differential amplifier 30i detects a result value indicating the level of the pin signal based on the potential between both ends of a composite coil including the three loop coils LCx connected in series, and outputs the result value as a reception signal Rx_EMR to the sensor control unit 31.

[0060] Fig. Figures 4 to 6 illustrate connections in the three connection modes. In particular, the example of Fig. 4 the loop coil LCx n-1 counterclockwise (written as “-1” in Fig. 4) when viewed from the non-inverting input terminal of the differential amplifier 30i. Subsequently, the loop coil LCx n clockwise (written as “1” in Fig. 4). Finally, the loop coil LCx n+1 counterclockwise. Moreover, in the example of Fig. 5 the loop coil LCx n-1 clockwise when viewed from the non-inverting input terminal of the differential amplifier 30i. Subsequently, the loop coil LCx n counterclockwise. Finally, the loop coil LCx n+1 counterclockwise. In the example of Fig. 6 the loop coil LCx n-1counterclockwise when viewed from the non-inverting input terminal of the differential amplifier 30i. Subsequently, the loop coil LCx n counterclockwise. Finally, the loop coil LCx n+1 connected clockwise.

[0061] Fig. Figure 11 is a diagram describing the received signal Rx_EMR passed from the differential amplifier 30i to the sensor control unit 31 as a result of the connections. Illustrated pin signal detection periods T1 to T3 correspond to the connection states of Fig. 4 to 6. Although the export period of the changing magnetic field (see Fig. 10) is actually located in the first half of each pin signal detection period, this is in Fig. 11. In addition, although the actual received signal Rx_EMR is attenuated over time, as shown in Fig. As illustrated in Figure 10, the attenuation in Fig. 11 is not illustrated to facilitate understanding. This is in Fig. 12 and Fig. 13 similar, which will be described later.

[0062] Out of Fig. 11 shows that the phase of the pen signal coming from the loop coil LCx n received, and the phase of the pen signal received by the loop coils LCx n-1 and LCx n+1 received in the pin signal detection period T1 are opposite. The reason is that the loop coil LCx n is clockwise and the loop coils LCx n-1 and LCx n+1 counterclockwise, as described above. Due to the assumption that the levels of the pen signal coming from the loop coils LCx n-1 up to LCx n+1 is received when the sensor control unit 31 detects the changing magnetic field in the linear electrode EL m generated as level E m,n-1to E m,n+1 , the reception signal Rx_EMR (result value) supplied from the differential amplifier 30i to the sensor control unit 31 in the pin signal detection period T1 is replaced by -E m,n-1 +E m,n -E m,n+1 shown as in Fig. 11. This is also similar in the pin signal detection periods T2 and T3 and the received signal Rx_EMR is represented by +E m,n-1 -E m,n -E m,n+1 or -E m,n-1 -E m,n +E m,n+1 shown.

[0063] A vector d series , which is illustrated in the following equation (7), is a description in a vector format of the received signals Rx_EMR received in the pin signal detection periods T1 to T3. As illustrated in the last line of equation (7), the vector d seriesinto a form of the product of a 3 × 3 matrix F, which indicates the connection polarity in each pin signal detection period, and a vector indicating the levels E m,n-1 to E m,n+1 Note that the matrix F illustrated in equation (7) contains a 3 × 3 Walsh code. [Math. 7] dseries=(−Em,n−1+Em,n−Em,n+1+Em,n−1−Em,n−Em,n+1−Em,n−1−Em,n+Em,n+1) =(−11−11−1−1−1−11)(Em,n−1 Em,nEm,n+1)=F(Em,n−1 Em,nEm,n+1)

[0064] The sensor control unit 31 performs a calculation on the vector d series through, as illustrated on the left side of the following equation (8), to determine the levels E m,n-1 to E m,n+1 to separate and raise, Here is a matrix F -1, which is illustrated in equation (8), is an inverse matrix of the matrix F, and therefore, the calculation illustrated on the left side of equation (8) is a recovery calculation according to the connection polarity of the loop coil LCx in each connection mode. As also illustrated in equation (8), an identity matrix I is obtained by multiplying the matrix F by the matrix F -1 Therefore, the sensor control unit 31 can perform the recovery calculation to determine the levels E m,n-1 to E m,n+1 of the pin signal and to collect the signals from the loop coils LCx n-1 up to LCx n+1 , can be obtained when the alternating magnetic field from the m-th linear electrode EL m is exported, as illustrated on the right side of equation (8). [Math. 8] F−1Dseries=F−1F(Em,n−1 Em,nEm,n+1)=I(Em,n−1 Em,nEm,n+1)=(Em,n−1 Em,nEm,n+1)

[0065] The sensor control unit 31 performs a calculation similar to equation (8) on each set of loop coils LCx to separate and collect the levels of the pen signal received by the plurality of loop coils LCx when the alternating magnetic field from the m-th linear electrode EL m The sensor control unit 31 also performs similar processes while the linear electrode EL m which exports the alternating magnetic field, to thereby increase the levels of the pen signal received by the plurality of loop coils LCx when the alternating magnetic field from each of the plurality of linear electrodes EL mis exported. The sensor control unit 31 then derives the position (two-dimensional position) of the electromagnetic resonance stylus P based on the distribution of the detected levels of the stylus signal in the touch area. Specifically, the sensor control unit 31 can derive the position corresponding to the peak of the distribution as the position of the electromagnetic resonance stylus P. The details of the position detection of the electromagnetic resonance stylus P performed by the sensor control unit 31 will be described in more detail later with reference to Fig. 15 to 17 described.

[0066] Here, comparative examples in which methods different from the present embodiment are used to receive the pen signal are illustrated to describe an advantageous effect of using the present embodiment.

[0067] Fig. 12 is a diagram describing the received signal Rx_EMR according to a first embodiment. The sensor control unit 31 according to the present embodiment connects a loop coil LCx to the differential amplifier 30i in each pin signal detection period. In this case, the level of the pin signal received by a loop coil LCx can be obtained in the pin signal detection period, and the sensor control unit 31 can acquire the level of the pin signal received by each loop coil LCx without performing the calculation.

[0068] Fig. 13 is a diagram describing the received signal Rx_EMR according to a second comparative example. The sensor control unit 31 according to the present comparative example connects three adjacent loop coils LCx to the differential amplifier 30i in series in each pin signal detection period as in the present embodiment. However, the sensor control unit 31 according to the present comparative example connects all of the loop coils LCx in the same direction (clockwise or counterclockwise). In this case, although the levels of the pin signal received by the loop coils LCx cannot be separated by calculation, the sensor control unit 31 may assume that the received signal Rx obtained by the three loop coils LCx is obtained by the loop coil LCx positioned at the center of the three loop coils LCx to derive the position of the electromagnetic resonance pin P.

[0069] Fig. 14 is a diagram illustrating results of a simulation of the levels of the pen signal (levels after separation when the levels are separated and raised) generated by the loop coils LCx near the loop coil LCx n be received when the electromagnetic resonance pin P on the loop coil LCx n is positioned. Fig. 14 illustrates results of the present embodiment ( Fig. 11), the first comparative example ( Fig. 12) and the second comparative example ( Fig. 13). As in Fig. 14, the pen signal reception method according to the present embodiment can achieve an advantageous effect that the reception level of the pen signal is significantly higher than in the first and second comparative examples. This is because, according to the pen signal reception method of the present embodiment, the pen signal detection period that can be used to obtain the pen signal received by the individual loop coils LCx is three times the pen signal detection period in the first and second comparative examples. Here, as described later, when the pen signal detection period of the pen signal in the sensor control unit 31 is increased by N times, the level of the received pen signal is increased by N times, but the level of the received noise is only increased by N times. 1 / 2-fold. Therefore, it can be said that the pen signal receiving method according to the present embodiment can improve the S / N ratio of the pen signal received by the sensor control unit 31.

[0070] In addition, according to the pen signal receiving method in the present embodiment, a receiving circuit can simultaneously receive the pen signals received by a plurality of loop coils LCx in each of the plurality of pen signal detection periods, and the received signal Rx_EMR can be separated into components of individual loop coils LCx. Therefore, the transmission period of the pen signal does not need to be increased to improve the S / N ratio, and there is no need to add a receiving circuit for a plurality of loop coils LCx to receive the pen signal in parallel. Therefore, it can be said that the pen signal receiving method according to the present embodiment can improve the S / N ratio of the pen signal received by the sensor control unit 31 without reducing the position detection frequency and without increasing the circuit scale of the sensor control unit 31.

[0071] As a result, the fact that the noise level is only around the N 1 / 2 -fold when the pin signal detection period of the pin signal in the sensor control unit 31 is increased by N times will be described in detail.

[0072] The received signal Rx collected in a k-th pin signal detection period is given by X k and the variance of X k is given by V(X k ). Due to the additivity of variance, a variance V TOTAL a signal (hereinafter referred to simply as “addition signal”) obtained by adding N received signals X1 to X N collected in first to N-th pen signal detection periods are represented by the total variance of the received signals Rx in the individual pen signal detection periods, as illustrated in the following equation (9). [Math. 9] VTOTAL=V(X1)+V(X2)+V(X3)+⋯+V(XN)

[0073] If only the noise components contained in the received signal Rx are considered, it can be assumed that the values ​​of the noise are the same in all pen signal detection periods, and the variance V TOTAL The addition signal is further represented by the following equation (10). Here, V and σ represent the variance and standard deviation, respectively, in the individual pen signal detection periods. [Math. 10] VTOTAL=V+V+V+⋯+V=N⋅V=N⋅σ2

[0074] The amount of noise that appears in the addition signal is given by a standard deviation σ TOTAL of the addition signal. Based on equation (10), the standard deviation σ TOTAL represented by the following equation (11). Therefore, it is clear that the noise level is only around the N 1 / 2 -fold when the pin signal detection period of the pin signal in the sensor control unit 31 is increased by N times. [Math. 11] σTOTAL=VTOTAL=Nσ

[0075] Next, the position detection of the electromagnetic resonance pin P performed by the sensor control unit 31 will be described in more detail with reference to flowcharts.

[0076] Fig. 15 to 17 are flowcharts illustrating the entire process of position detection of the electromagnetic resonance pin P, which is carried out by the sensor control unit 31. First, in Fig. 15, the sensor control unit 31, before detecting the electromagnetic resonance pin P, selects the linear electrodes EL, excluding the two linear electrodes EL at each end, as selection targets (step S1) and selects the linear electrode EL at the outermost end among the linear electrodes EL as the selection targets (step S2). In addition, the sensor control unit 31 selects three loop coils LCx from the end and controls the switches 30c to 30e to connect the selected three loop coils LCx to the differential amplifier 30i in a first connection mode (for example, the connection mode shown in Fig. 4) (step S3).

[0077] Subsequently, the sensor control unit 31 begins to export the alternating magnetic field from the selected linear electrode EL (step S4). In particular, as shown in Fig. 4, the sensor control unit 31 controls the switch 30a to connect the two adjacent linear electrodes EL on one side via the selected linear electrode EL to the output terminals of the alternating current i A in the driver circuit 30g (output terminals of buffer circuit) and the two adjacent linear electrodes EL on the other side via the selected linear electrode EL with the output terminals of the alternating current i Bin the driver circuit 30g (output terminals of the inverting buffer circuit) to begin supplying the alternating current Tx_EMR to the driver circuit 30g. The sensor control unit 31 then temporarily stores the level of the received signal Rx_EMR output from the differential amplifier 30i according to the changing magnetic field exported in step S4 (step S5). The level of the received signal Rx_EMR stored here may, for example, be the maximum value in the entire position derivation period, as shown in Fig. 10A (including the position derivative period which is the export period of the alternating magnetic field and the position derivative period after the export period of the alternating magnetic field), or may be the maximum value in the position derivative period after the export period of the alternating magnetic field.

[0078] Subsequently, the sensor control unit 31 determines whether or not the process for steps S4 and S5 has been attempted in all of the connection modes (step S6). Specifically, the sensor control unit 31 determines whether or not the process for steps S4 and S5 has been attempted in all of the three connection modes shown in Fig. 4 to 6. The sensor control unit 31, having determined that the process has not been attempted in all of the connection modes, controls the switches 30c to 30e to connect the selected three loop coils LCx to the differential amplifier 30i in the next connection mode (for example, the connection mode shown in Fig. 5, according to the connection mode shown in Fig. 4, or the connection mode shown in Fig. 6, according to the connection mode shown in Fig. 5) (step S7), and returns to step S4.

[0079] On the other hand, the sensor control unit 31, which has determined in step S6 that the process has been attempted in all of the connection modes, derives the level of the pin signal of each loop coil LCx based on the levels of the plurality of reception signals Rx_EMR temporarily stored in the plurality of attempts in step S5 (step S8). Specifically, the sensor control unit 31 performs the recovery calculation illustrated in equation (8).

[0080] Subsequently, the sensor control unit 31 determines whether the selection of all loop coils LCx is completed or not (step S9). If the sensor control unit 31 determines that the selection is not completed, the sensor control unit 31 selects three loop coils LCx adjacent to the three loop coils LCx that were last selected (three loop coils selected in step S3 or step S10) and controls the switches 30c to 30e to connect the three loop coils LCx to the differential amplifier 30i in the first connection mode (for example, the connection mode selected in Fig. 4) (step S10). The sensor control unit 31 then returns to step S4. On the other hand, if the sensor control unit 31 determines in step S9 that the selection is completed, the sensor control unit 31 determines whether or not the selection of all the linear electrodes EL determined as the selection targets in step S1 is completed (step S11). If the sensor control unit 31 determines that the selection is not completed, the sensor control unit 31 selects the linear electrode EL adjacent to the linear electrode EL that was last selected (linear electrode EL selected in step S2 or step S12) (step S12) and returns to step S4.

[0081] The sensor control unit 31, which has determined in step S11 that the selection is completed, determines whether or not the pen signal has been detected based on the level of the pen signal in each combination of the linear electrode EL and the loop coil LCx as obtained by repeating step S8 (step S13 of Fig. 16). In one example, the result of the determination is positive if there is a level that exceeds a predetermined value, and in other cases the result of the determination is negative.

[0082] The sensor control unit 31, which has determined that the pin signal is not detected in step S13, returns to step S1 of Fig. 15 and continues the process. On the other hand, the sensor control unit 31, having determined that the pin signal is detected, derives the position of the electromagnetic resonance pin P based on the level of the pin signal in each combination of the linear electrode EL and the loop coil LCx determined in step S8 of Fig. 15 and outputs the position to the host processor 32 (step S14).

[0083] Subsequently, the sensor control unit 31 determines (updates) a predetermined number of (a number smaller than the number of linear electrodes EL used as the selection targets in step S1 of Fig. 15, which is typically three or four) linear electrodes EL (linear electrode set) and 3n (n is a natural number, which is typically n = 1, where 3n is a number smaller than the total number of loop coils LCx) loop coils LCx based on the position derived in step S14 (position derived in step S28 last in the case of a transition from step S28, which will be described later) (step S15).

[0084] Subsequently, the sensor control unit 31 selects the linear electrode EL at the outermost end from the linear electrodes EL as the selection targets (step S16). The sensor control unit 31 then selects three loop coils LCx from the end from the loop coils LCx as the selection targets and controls the switches 30c to 30e that connect the selected three loop coils LCx to the differential amplifier 30i in the first connection mode (for example, the connection mode shown in Fig. 4) (step S17).

[0085] In Fig. 17, the sensor control unit 31 performs a process similar to steps S4 to S13 of Fig. 15 and Fig. 16 (steps S18 to S27). However, the process here differs from the process for steps S4 to S14 in that, while only the level of the received signal Rx_EMR is temporarily stored in step S5, a series of digital values ​​(obtained by sampling) included in the received signal Rx_EMR is also stored in step S19. The processes are different in that, while it is determined in step S9 whether the selection of all the loop coils LCx is completed or not, it is determined in step S23 whether the selection of all the loop coils LCx determined as the selection targets in S15 is completed or not.The processes are different in that, while in step S11 it is determined whether the selection of all the linear electrodes EL determined as the selection targets in step S1 is completed or not, in step S25 it is determined whether the selection of all the linear electrodes EL determined as the selection targets in step S15 is completed or not. Note that the series of digital values ​​stored in step S19 can only be the values ​​in the position derivation and data reception period specified in . Fig. 10A are illustrated.

[0086] The sensor control unit 31, which has determined in step S27 that the stylus signal is detected, derives the position of the electromagnetic resonance stylus P, collects the data transmitted from the electromagnetic resonance stylus P, and outputs the data to the host processor 32 (step S28). Specifically, the sensor control unit 31 derives the position of the electromagnetic resonance stylus P based on the level of the stylus signal in each combination of the linear electrode EL and the loop coil LCx derived in step S22. In addition, the sensor control unit 31 demodulates the series of digital values ​​stored in step S19 relative to the combination of the linear electrode EL and the loop coil LCx closest to the derived position, thereby collecting the data transmitted from the electromagnetic resonance stylus P.After the end of step S28, the sensor control unit 31 returns to step S15 and continues the process.

[0087] When the process is adopted, the sensor control unit 31 according to the present embodiment may test the linear electrode set once in step S15 of Fig. 16 and then export the alternating magnetic fields from only a predetermined number of linear electrodes EL included in the linear electrode set, thereby updating the two-dimensional position of the electromagnetic resonance pin P. This can prevent the increase in power consumption even if the linear electrodes EL replace the Tx coils.

[0088] As described above, the position detection system 1 according to the present embodiment can specify the linear electrode set once and then export the alternating magnetic fields only from a predetermined number of linear electrodes EL included in the linear electrode set, thereby updating the two-dimensional position of the electromagnetic resonance pen P. This can prevent the increase in power consumption even when the linear electrodes EL replace the Tx coils.

[0089] In addition, the position detection system 1 according to the present embodiment can prevent occurrence of a phase shift between the current flowing through the linear electrodes EL m-1 and EL m-2 and the current flowing through the linear electrodes EL m+1 and EL m+2This can reduce the noise superimposed on the alternating magnetic fields detected by the Rx coils (loop coils LCx) when the linear electrodes EL replace the Tx coils.

[0090] In addition, the position detection system 1 according to the present embodiment can improve the S / N ratio of the pen signal received by the sensor control unit 31 without reducing the frequency of position detection and without increasing the circuit scale of the sensor control unit 31.

[0091] In addition, according to the position detection system 1 of the present embodiment, a set of linear electrodes EL arrayed and arranged in the y-direction and a set of loop coils LCx arrayed and arranged in the x-direction can realize both the EMR sensor and the touch sensor (sensor that uses the capacitance system to detect a touch of the finger F). This can achieve weight reduction and cost reduction of the position detection device compared to the case where the EMR sensor and the touch sensor are provided separately in one position detection device.

[0092] Additionally, according to the position detection system 1 of the present embodiment, the differential amplifier 30i is used to receive the received signal Rx_EMR. Therefore, even if resistance values ​​among the loop coils LCx vary, the variations in the pin signal levels can be suppressed. This is particularly effective when the loop coils LCx include a high-impedance material, such as a metal mesh.

[0093] Incidentally, although in the example described in the present embodiment, the matrix F illustrated in equation (7) is a matrix represented by a 3 × 3 Walsh code, a matrix represented by a code other than the Walsh code, such as an OVSF code, an M-sequence code, and a Baker code, can be suitably used as the matrix F (that is, the connection mode of the loop coils LCx in each pen signal detection period can be set so that the matrix F is one of these codes).

[0094] This will be generalized and described. When k loop coils LCx are simultaneously connected in series to the differential amplifier 30i (that is, when the sensor control unit 31 controls the switch 30c so that sets of k adjacent loop coils LCx are selected in sequence while the alternating magnetic field is exported from one of the linear electrodes EL, and each time the set is selected, the k loop coils LCx included in the selected set are connected in series to the differential amplifier 30i in k connection modes with different connection polarities), the connection mode of the loop coils LCx in each pin signal detection period can be determined based on the matrix F if the rank of the matrix F (matrix of k rows and k columns) is k as a coefficient matrix of simultaneous equations represented by the following equation (12).In other words, if column vectors of the matrix F are linearly independent of each other, the connection mode of the loop coils LCx in each pin signal detection period can be determined based on the matrix F. The reason is that equation (12) always has a solution in every case. [Math. 12] F( Em,nEm,n+1Em,n+2 ⋮Em,n+k)=dseries

[0095] In addition, although the inverse matrix F -1 of the matrix F is used to perform the recovery calculation in the example described in the present embodiment, a matrix other than the inverse matrix may also be used to perform the recovery calculation. The following illustrates an example of the case where the vector d series, which is illustrated in equation (7), is obtained to describe an example of the recovery calculation in which the matrix F is used as the matrix which is not the inverse matrix of the matrix F.

[0096] In the example, the matrix F for recovery and the levels -E m,n-1 +E m,n -E m,n+1 , +E m,n-1 -E m,n -E m,n+1 , and -E m,n-1 -E m,n +E m,n+1 of the received signal Rx in the pin signal detection periods T1 to T3 is first used to derive the level of the received signal Rx corresponding to the case where all columns of the matrix F are 1. Specifically, simultaneous equations illustrated in the following equation (13) can be solved to obtain a, b, and c, and a + b + c can be derived to derive the level of the received signal Rx corresponding to the case where all columns of the matrix F are 1. The level derived in this way is +Em,n-1 +E m,n +E m,n+1 . [Math. 13] (−11−11−1−1−1−11)(abc)=(−Em,n−1+Em,n−Em,n+1+Em,n−1−Em,n−Em,n+1−Em,n−1−Em,n+Em,n+1)

[0097] Then, as illustrated in the following equation (14), a column in which the values ​​of all elements are 1 is added to the top of the matrix F and a row with a value of +E m,n-1 +E m,n +E m,n+1 is at the top of the vector d series added. The matrix F is multiplied by the vector d series multiplied. In this way, a result obtained by linearly amplifying (specifically, a fourfold increase) the calculation result of equation (8) can be obtained. [Math. 14] (1−11−111−1−11−1−11)(+Em,n+1+Em,n+Em,n+1−Em,n+1+Em,n−Em,n+1+Em,n−1−Em,n−Em,n+1−Em,n−1−Em,n+Em,n+1) =4(Em,n−1 Em,nEm,n+1)

[0098] In this way, if a matrix that is not the inverse matrix F -1 of the matrix F is used to perform the recovery calculation, the level of the received signal Rx must be derived, corresponding to the case where the column of the matrix F consists entirely of 1. The levels E m,n-1 to E m,n+1 can, however, be separated and collected, as in the case of using the inverse matrix F -1 the matrix F to perform the recovery calculation.

[0099] Although the result obtained by amplifying the calculation result of equation (8) fourfold is shown in equation (14), the increase in the calculation result leads to an improvement in the accuracy of calculation in the later stage, and this is preferable. This also applies to the case of using the inverse matrix F. -1of the matrix F to perform the recovery calculation. A specific example is illustrated to describe this.

[0100] The vector d series For a case where the matrix F is a 4 × 4 Walsh code, it is represented by the following equation (15). Here, a vector e is a vector indicating the levels of the pen signal received by four loop coils LCx. [Math. 15] dseries=Fe=(11111−11−111−1−11−1−11)e

[0101] The inverse matrix F -1 the matrix F illustrated in equation (15) is represented by equation (16). [Math. 16] F−1=14(1 1 1 11−1 1−11 1−1−11−1−1 1)

[0102] Therefore, in the recovery calculation of the vector e, the inverse matrix F -1be multiplied by 4, as illustrated in the following equation (17), to obtain a vector with four times the level of the original vector e, even if the inverse matrix F -1 used to perform the recovery calculation. [Math. 17] 4F−1dseries=(1 1 1 11−1 1−11 1−1−11−1−1−1 1)dseries=(1 1 1 11−1 1−11 1−1−11−1−1 1)(1 1 1 11−1 1−11 1−1−11−1−1 1)e=4e

[0103] Next, the position detection system 1 according to a second embodiment of the present invention will be described.

[0104] Fig. 18 is a diagram illustrating an internal configuration of the switching unit 30 arranged in the position detection device 3 included in the position detection system 1 according to the present embodiment. The switching unit 30 according to the present embodiment differs from the switching unit 30 according to the first embodiment in that the wiring unit 30h does not include the wires L1 and L2, the switch 30c does not include the output pins corresponding to the wires L1 and L2, and includes an operational amplifier 30n instead of the differential amplifier 30i. The switch 30d according to the present embodiment plays a role in connecting the wire L4 to the input terminal of the operational amplifier 30n and connecting the wire L3 to the ground terminal under the control of the sensor control unit 31.In addition, the sensor control unit 31 according to the present embodiment differs from the sensor control unit 31 according to the first embodiment in that three loop coils LCx are connected to the operational amplifier 30n in parallel rather than in series to detect the position of the electromagnetic resonance pin P. The position detection system 1 according to the present embodiment is similar to the position detection system 1 according to the first embodiment in other respects, and the description will continue with a focus on the differences from the position detection system 1 according to the first embodiment.

[0105] Fig. 19 to 21 are diagrams illustrating states of the switching unit 30 when the sensor control unit 31 according to the present embodiment detects the position of the electromagnetic resonance pin P. While the sensor control unit 31 according to the present embodiment detects the alternating magnetic field from the linear electrode EL mexported, the sensor control unit 31 executes a process to sequentially detect sets of loop coils LCx, each set including three adjacent loop coils LCx, and each time the set is selected, controls the switch 30c to connect the three loop coils LCx included in the selected set in parallel to the operational amplifier 30n in three connection modes with different connection polarities. As a result of the process, the operational amplifier 30n detects a result value indicating the level of the pin signal based on the potential (potential with respect to the ground end) at one end of a composite coil including the three loop coils LCx connected in parallel, and outputs the result value as the reception signal Rx_EMR to the sensor control unit 31.

[0106] Fig. Figures 19 to 21 illustrate connections in the three connection modes. In particular, in the example of Fig. 19 the loop coils LCx n-1 and LCx n+1 counterclockwise (written as “-1” in Fig. 19) and the loop coil LCx n is connected clockwise (written as “1” in Fig. 19) when viewed from the input terminal of the operational amplifier 30n. Moreover, in the example of Fig. 20 the loop coil LCx n-1 connected clockwise and the loop coils LCx n and LCx n+1 are connected counterclockwise when viewed from the input terminal of the operational amplifier 30n. In the example of Fig. 21 are the loop coils LCx n-1 and LCx n counterclockwise and the loop coil LCx n+1 is connected clockwise when viewed from the input terminal of the operational amplifier 30n.

[0107] As a result of the connections, the received signal Rx_EMR, which is passed from the operational amplifier 30n to the sensor control unit 31, is represented by a vector d parallel which is illustrated in the following equation (18). The meaning of the levels E m,n-1 to E m,n+1 , as illustrated in equation (18), is as described in the first embodiment. As illustrated in the last line of equation (18), the vector d parallel also in a form of the product of the 3 × 3 matrix F, which indicates the connection polarity in each pin signal detection period, and the vector indicating the levels E m,n-1 to E m,n+1 with the vector d series which is described in the first embodiment. [Math. 18] dparallel=(−Em,n−1+Em,n−Em,n+1+Em,n−1−Em,n−Em,n+1−Em,n−1−Em,n+Em,n+1) =(−11−11−1−1−1−11)(Em,n−1 Em,nEm,n+1)=F(Em,n−1 Em,nEm,n+1)

[0108] As can be seen from the fact that the shape of the vector d parallel is the same as the shape of the vector d series , the sensor control unit 31 in the present embodiment can also calculate the vector d parallel with the inverse matrix F -1 of the matrix F to obtain the levels E m,n-1 to E m,n+1 of the pin signal coming from the loop coils LCx n-1 up to LCx n+1is received. Therefore, the pen signal receiving method according to the present embodiment can also achieve advantageous effects similar to the advantageous effects of the first embodiment. In particular, the increase in power consumption can be prevented even when the linear electrodes EL replace the Tx coils. In addition, when the linear electrodes EL replace the Tx coils, the reduction in noise superimposed on the alternating magnetic fields detected by the Rx coils (loop coils LCx) can also be reduced. Moreover, the S / N ratio of the pen signal received by the sensor control unit 31 can be improved without reducing the position detection frequency and without increasing the circuit scale of the sensor control unit 31.However, in comparison, the inductance in the case of connecting the plurality of loop coils LCx in parallel is lower than in the case of connecting the plurality of loop coils LCx in series, and the level of the pen signal in the present embodiment is lower than that of the first embodiment. Therefore, it can be said that the advantageous effect of improving the S / N ratio of the pen signal is higher in the first embodiment than in the present embodiment.

[0109] Next, the position detection system 1 according to a third embodiment of the present invention will be described.

[0110] Fig. Fig. 22 is a diagram illustrating an internal configuration of the switching unit 30 arranged in the position detection device 3 included in the position detection system 1 according to the present embodiment. For the sake of simplicity, Fig. 22 only five loop coils LCx (loop coils LCx n-2 up to LCx n+2 ) and six linear electrodes EL (linear electrodes EL m to EL m+5 ). This is also the case in Fig. 23 to 25, which will be described later.

[0111] The switching unit 30 according to the present embodiment differs from the switching unit 30 according to the second embodiment in that the switching unit 30 according to the present embodiment includes a switch 30k instead of the switch 30a and includes a driver circuit 30m instead of the driver circuit 30g. In addition, the sensor control unit 31 according to the present embodiment differs from the sensor control unit 31 according to the second embodiment in that the sensor control unit 31 according to the present embodiment provides the six linear electrodes EL m to EL m+5AC current at a time and connects only one loop coil LCx to the operational amplifier 30n at a time to detect the position of the electromagnetic resonance pin P. The position detection system 1 according to the present embodiment is similar to the position detection system 1 according to the second embodiment in other respects, and the description will continue with an emphasis on the differences from the position detection system 1 according to the second embodiment.

[0112] The switch 30k is configured to supply the alternating current Tx_EMR to the plurality of linear electrodes EL for generating the alternating magnetic field on the touch surface. The switch 30k includes output pins corresponding to the linear electrodes EL, and two input pins are provided for each output pin. Each output pin is connected to one end of the corresponding linear electrode EL in the x-direction (longitudinal direction). The switch 30k plays a role in connecting each input pin to one of the output pins in each linear electrode EL under the control of the sensor control unit 31.

[0113] The driver circuit 30m is a circuit that converts the alternating currents i A and i B according to the alternating current Tx_EMR supplied from the sensor control unit 31, and the alternating currents i A and i Bthrough the switch 30k to the linear electrodes EL. The driver circuit 30m is configured to supply the alternating current i A to one of the two input pins corresponding to each linear electrode EL and the alternating current i B to the other input pin.

[0114] Fig. 23 to 25 are diagrams illustrating states of the switching unit 30 when the sensor control unit 31 according to the present embodiment detects the position of the electromagnetic resonance pin P. While the loop coil LCx nconnected to the operational amplifier 30n under the control of the switches 30c to 30e, the sensor control unit 31 according to the present embodiment sequentially selects six adjacent linear electrodes EL while shifting the target by three linear electrodes EL each time. Each time, the sensor control unit 31 performs a process of controlling the switch 30c to connect the selected six linear electrodes EL to the driver circuit 30m in three connection modes, so that the alternating current i A is generated in half of the six linear electrodes EL and the alternating current i B is generated in the remaining half.

[0115] Fig. Figures 23 to 25 illustrate the supply of alternating currents in the three connection modes. In particular, the example of Fig. 23the alternating current i A to the linear electrodes EL m+1 , EL m+3 and EL m+5and the alternating current i B becomes the linear electrodes EL m , EL m+2 and EL m+4 Additionally, in the example of Fig. 24 the alternating current i A to the linear electrodes EL m+1 to EL m+3 and the alternating current i B becomes the linear electrodes EL m , EL m+4 and EL m+5 The alternating current i A is shown in the example of Fig. 25to the linear electrodes EL m+2 to EL m+4 and the alternating current i B becomes the linear electrodes EL m , EL m+1 and EL m+5 led.

[0116] Fig. 26(a) to 26(c) are diagrams schematically showing methods for supplying the alternating currents in Fig. 23 to 25 illustrate. Fig. 26(d) to 26(f) are diagrams illustrating equivalent circuits when the methods described in Fig. 26(a) to 26(c) are illustrated, for supplying the alternating currents i A and i B to the six linear electrodes EL m to EL m+5 be used. As in Fig. 26(a) to 26(f) illustrates when the alternating currents in which the phases of time derivatives are opposite are applied to a linear electrode EL m+k (k is one of 0, 1 and 2) and a linear electrode EL m+k+3 applied, it can be assumed that the linear electrode EL m+k and the linear electrode EL m+k+3 form a loop coil, independent of the current flowing through the linear electrodes EL m+k+1 and EL m+k+2 flows between the linear electrode EL m+k and the linear electrode EL m+k+3 In the following, the loop coil is referred to as a “pseudo-loop coil PLC” and in particular, the pseudo-loop coil PLC formed by the linear electrodes ELm+k and EL m+k+3 is formed as a “pseudo loop coil PLC m+k The connection polarity of the pseudo loop coil PLC m+k in case of supplying the alternating current i A to the linear electrode EL m+k and supplying the alternating current i B to the linear electrode EL m+k+3 (written as “-“ in Fig. 26(a) to 26(f)) and the connection polarity of the pseudo loop coil PLC m+k in case of supplying the alternating current i B to the linear electrode EL m+k and supplying the alternating current i A to the linear electrode EL m+k+3 (written as “+” in Fig. 26(a) to 26(f)) are opposite.

[0117] The level of the pen signal coming from the loop coil LCx n is received when the alternating current i A the linear electrode EL m+k and the alternating current i Bthe linear electrode EL m+k+3 is supplied by E m+k,n The received signal Rx_EMR (result value) supplied from the operational amplifier 30n to the sensor control unit 31 when the alternating currents are supplied as shown in Fig. 26(a) is illustrated by - E m,n +E m+1,n -Em +2,n This is similar if the alternating currents are as in Fig. 26(b) and Fig. 26(c) and the received signals Rx_EMR are represented by E m,n -E m+1,n -Em +2,n or -E m,n -E m+1,n +Em +2,n When expressed in a vector format, this is represented by a vector d tx which is illustrated in the following equation (19). Moreover, the vector d tx to a form of the product of the 3 × 3 matrix F, which indicates the connection polarity of the pseudo-loop coil PLC, and the vector indicating the levels Em,n to E m+2,n represents, be transformed, as with the vector d series and the vector d parallel . [Math. 19] dtx=(−Em,n+Em+1,n−Em+2,n+Em,n−Em+1,n−Em+2,n−Em,n−Em+1,n+Em+2,n)=(−11−11−1−1−1−11)( Em,nEm+1,nEm+2,n)=F( Em,nEm+1,nEm+2,n)

[0118] As can be seen from the fact that the vector d tx has the same form as the vector d series and the vector d parallel , the sensor control unit 31 in the present embodiment can also calculate the vector d tx with the inverse matrix F -1 the matrix F to get the levels E m,n , E m+1,n and E m+2,n of the pen signal received when the alternating magnetic fields from the pseudo loop coils PLC m to PLC m+2exported, separate, and collect them. Moreover, according to the method for supplying the alternating currents of the present embodiment, the length of the period in which the alternating magnetic field is exported from each pseudo-loop coil PLC is three times longer than in the case of independently exporting the alternating magnetic fields from three pseudo-loop coils PLC. While the level of the received pin signal is increased threefold, the level of the received noise is just 3 1 / 2 -fold. Therefore, it can be said that the method of supplying the alternating currents according to the present embodiment can improve the S / N ratio of the pin signal received by the sensor control unit 31.

[0119] Fig. 27 to 29 are flowcharts illustrating the entire process of position detection of the electromagnetic resonance pin P performed by the sensor control unit 31 according to the present embodiment. First, in Fig. 27, the sensor control unit 31 selects a loop coil LCx at the outermost end before detecting the electromagnetic resonance pin P and controls the switch 30b to connect the selected loop coil LCx to the operational amplifier 30n (step S30). The process also includes a process for controlling the switch 30d to connect the wire L4 to the operational amplifier 30n and ground the wire L3, and controlling the switch 30e to disconnect the operational amplifier 30j from the wire L4.

[0120] Then, the sensor control unit 31 selects six linear electrodes EL from the end and controls the switch 30k to connect the six linear electrodes EL to the driving circuit 30m in a connection mode (for example, connection mode shown in Fig. 23) (step S31). The process also includes a process for controlling the switch 30f to ground the other end of each linear electrode EL in the x-direction, and a process for controlling the switch 30b to prevent supply of the touch detection signal Tx_TP to each linear electrode EL.

[0121] Subsequently, the sensor control unit 31 begins to export the alternating magnetic fields from the selected linear electrode group EL (step S32). Specifically, the sensor control unit 31 begins to conduct the alternating current Tx_EMR to the driver circuit 30m. In this way, one of the alternating currents i A and i Bthrough each of the six linear electrodes EL. As a result, the pseudo loop coil PLC is formed, and the alternating magnetic fields are exported. Subsequently, the sensor control unit 31 temporarily stores the level of the reception signal Rx_EMR output from the operational amplifier 30n according to the alternating magnetic fields exported in step S32 (step S33). The exact details of the levels stored here can be similar to that in step S5 of Fig. 15 stored levels.

[0122] Subsequently, the sensor control unit 31 determines whether the process for steps S32 and S33 has been attempted in all of the connection modes or not (step S34). Specifically, the sensor control unit 31 determines whether the process for steps S32 and S33 has been attempted in all of the three connection modes shown in Fig. 23 to 25, has been attempted or not. The sensor control unit 31, which has determined in the determination that the process has not been attempted in all of the connection modes, controls the switch 30k to connect the selected six linear electrodes EL to the driver circuit 30m in the next connection mode (for example, the connection mode shown in Fig. 24, according to the connection mode shown in Fig. 23, or the connection mode shown in Fig. 25, according to the connection mode shown in Fig. 24) (step S35) and returns to step S32.

[0123] On the other hand, the sensor control unit 31, which has determined in step S34 that the process has been attempted in all of the connection modes, derives the level of the pin signal of each pseudo-loop coil PLC based on the levels of the multiple reception signals Rx_RMP temporarily stored in the multiple attempts of step S5 (step S36). Specifically, the sensor control unit 31 performs a calculation (recovery calculation) by multiplying the vector d tx with the inverse matrix F -1 the matrix F.

[0124] Subsequently, the sensor control unit 31 determines whether the selection of all linear electrodes EL is completed or not (step S37). If the sensor control unit 31 determines that the selection is not completed, the sensor control unit 31 shifts the target by three linear electrodes and selects six linear electrodes EL. The sensor control unit 31 controls the switch 30k to connect the six linear electrodes EL to the driver circuit 30m in the first connection mode (for example, the connection mode shown in Fig. 23) (step S38) and then returns to step S32. On the other hand, if the sensor control unit 31 determines in step S37 that the selection is completed, the sensor control unit 31 determines whether the selection of all the loop coils LCx is completed or not (step S39). If the sensor control unit 31 determines that the selection is not completed, the sensor control unit 31 selects a loop coil LCx adjacent to a loop coil LCx that was last selected (loop coil LCx selected in step S30 or step S40) and controls the switch 30c to connect the loop coil LCx to the operational amplifier 30n (step S40). The sensor control unit 31 returns to step S32.

[0125] The sensor control unit 31, which has determined in step S39 that the selection is completed, determines whether the pen signal is detected or not based on the level of the pen signal in each combination of the pseudo loop coil PLC and the loop coil LCx obtained by repeating step S36 (step S41 of Fig. 28). In one example, the result of the determination is positive when there is a level that exceeds a predetermined value, and in other cases the result of the determination is negative.

[0126] The sensor control unit 31, which has determined in step S41 that the pin signal has not been detected, returns to step S30 of Fig. 27 and continues the process. On the other hand, the sensor control unit 31, which has determined that the pin signal has been detected, derives the position of the electromagnetic resonance pin P based on the level of the pin signal in each combination of the pseudo loop coil PLC and the loop coil LCx determined in step S36 of Fig. 27 and outputs the position to the host processor 32 (step S42).

[0127] Subsequently, the sensor control unit 31 determines, as selection targets, 3 + 3n (n is a natural number, which is typically n = 1, where 3 + 3n is a number smaller than the total number of linear electrodes EL) linear electrodes EL (linear electrode set) and a predetermined number of (a number smaller than the total number of loop coils LCx, which is typically three or four) loop coils LCx based on the position derived in step S42 (position derived in step S56 last time, in the case of a transition from step S56, as described later) (step S43).

[0128] Subsequently, the sensor control unit 31 selects the loop coil LCx at the outermost end from the loop coils LCx as the selection targets and controls the switch 30c to connect the loop coil LCx to the operational amplifier 30n (step S44). In addition, the sensor control unit 31 selects six linear electrodes EL from the end of the linear electrodes EL as the selection targets and controls the switch 30k to connect the selected six linear electrodes EL to the driver circuit 30m in the first connection mode (for example, the connection mode shown in Fig. 23) (step S45).

[0129] In Fig. 29, the sensor control unit 31 performs a process similar to steps S32 to S41 of Fig. 27 and Fig. 28 (steps S46 to S55). However, the process here differs from the process for steps S32 to S41 in that, while only the level of the received signal Rx_EMR is temporarily stored in step S33, a series of digital values ​​(obtained by sampling) included in the received signal Rx_EMR is also stored in step S47. The processes are different in that, while it is determined in step S37 whether the selection of all the linear electrodes EL is completed or not, it is determined in step S51 whether the selection of all the linear electrodes EL determined as the selection targets in S43 is completed. The processes are different in that, while it is determined in step S39 whether the selection of all the loop coils LCx is completed or not, it is determined in step S53 whether the selection of all the loop coils LCx determined as the selection targets in step S43 is completed or not.

[0130] The sensor control unit 31, which has determined in step S55 that the pin signal is detected, derives the position of the electromagnetic resonance pin P, collects the data transmitted from the electromagnetic resonance pin P, and outputs the data to the host processor 32 (step S56). Specifically, the sensor control unit 31 derives the position of the electromagnetic resonance pin P based on the level of the pin signal in each combination of the pseudo-loop coil PLC and the loop coil LCx derived in step S50. In addition, the sensor control unit 31 demodulates the series of digital values ​​stored in step S47 relative to the combination of the pseudo-loop coil PLC and the loop coil LCx closest to the derived position, thereby collecting the data transmitted from the electromagnetic resonance pin P.After the end of step S56, the sensor control unit 31 returns to step S43 and continues the process.

[0131] When the process is adopted, the sensor control unit 31 according to the present embodiment may test the linear electrode set once in step S43 of Fig. 28, and then export the alternating magnetic fields from only a predetermined number of linear electrodes EL included in the linear electrode set, thereby updating the two-dimensional position of the electromagnetic resonance pin P. This can prevent the increase in power consumption even if the linear electrodes EL replace the Tx coils.

[0132] As described above, the position detection system 1 according to the present embodiment can specify the linear electrode set once and then export the alternating magnetic fields only from a predetermined number of linear electrodes EL included in the linear electrode set, thereby updating the two-dimensional position of the electromagnetic resonance pen P. This can prevent the increase in power consumption even when the linear electrodes EL replace the Tx coils.

[0133] In addition, the position detection system 1 according to the present embodiment also conducts the alternating currents i A and i BTo one end (end portions on the same side) of the linear electrodes EL in the x-direction, the position detection system 1 can prevent the occurrence of a phase shift between the currents flowing through the linear electrodes EL. This can also reduce the noise superimposed on the alternating magnetic fields detected by the Rx coils (loop coils LCx) when the linear electrodes EL replace the Tx coils.

[0134] Although the preferred embodiments of the present invention have been described, the present invention is by no means limited to the embodiments and it is obvious that the present invention can be embodied in various ways without departing from the scope of the present invention.

[0135] For example, the example of generating the reception signal Rx_EMR based on the potential between both ends of the composite coil including three loop coils LCx connected in series is described in the first embodiment, and the example of generating the reception signal Rx_EMR based on the potential (potential with respect to the ground end) at one end of the composite coil including the three loop coils LCx connected in parallel is described in the second embodiment. However, when three loop coils LCx are connected in series, the reception signal Rx_EMR can be generated based on the potential (potential with respect to the ground end) at one end of the composite coil including the three loop coils LCx. When three loop coils LCx are connected in parallel, the reception signal Rx_EMR can be generated based on the potential between both ends of the composite coil including the three loop coils LCx.

[0136] In addition, although the examples of using three adjacent loop coils LCx as a set to detect the position of the electromagnetic resonance pin P were described in the first and second embodiments, two adjacent loop coils LCx may be used as a set, or four or more adjacent loop coils LCx may be used as a set. Alternatively, all of the loop coils LCx may be used as a set. The matrix F is an n × n matrix in a case of using n (n ≥ 2) loop coils LCx as a set.

[0137] In addition, although the examples of generating the reception signal Rx_EMR while using the switch 30c to change the connection modes of the plurality of loop coils LCx are described in the first and second embodiments, the reception signal Rx_EMR may be generated while changing the connection of the loop coils LCx and the calculation circuits. For example, in the pin signal detection period T1 shown in Fig. 11, the loop coils LCx n-1 and LCx n+1 be connected to a subtraction circuit and the loop coil LCx n can be connected to an addition circuit. In the pin signal detection period T2, the loop coils LCx n and LCx n+1 be connected to the subtraction circuit and the loop coil LCx n-1 can be connected to the addition circuit. In the pin signal detection period T3, the loop coil LCx nbe connected to the subtraction circuit and the loop coils LCx n-1 and LCx n+1 can be connected to the addition circuit.

[0138] Additionally, the technique of the present invention can be applied to generate the received signal Rx_EMR according to a connection mode of the loop coils LCx. For example, a difference E M,1 -E m,2 between the loop coil LCx1 and the loop coil LCx2 or a signal (E m,1 +E m,2 )-(E m,3 +E m,4 ), which is obtained by subtracting an addition signal of the loop coil LCx3 and the loop coil LCx4 from an addition signal of the loop coil LCx1 and the loop coil LCx2, can be generated. In this way, the level of the pin signal can be measured according to a connection mode of the loop coils LCx. DESCRIPTION OF REFERENCE SYMBOLS 1 position detection system 3 Position detection device 30 switch unit 30a to 30f, 30k switch 30g, 30m driver circuit 30h wiring unit 30i differential amplifier 30j, 30n operational amplifiers 31 Sensor control unit 32 host processor EL Linear Electrode F fingers L1 to L4 wire LCx loop coil P Electromagnetic resonance pin PA1, PA2 examination area PLC pseudo loop coil T1 to T3 pin signal detection period Tx, Tx_EMR alternating current Tx_TP touch detection signal Rx, Rx_EMR, Rx_TP receive signal QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 6698386

[0004]

Claims

[1] A sensor device that detects an indicator, the sensor device comprising: a linear electrode group extending in parallel; a detection coil group crossing the linear electrode group; and an integrated circuit connected to the linear electrode group and the detection coil group, wherein the integrated circuit is configured, to export alternating magnetic fields from the linear electrode group in sequence, to use the detection coil group to detect an alternating magnetic field generated by the indicator according to the alternating magnetic fields and to determine a linear electrode set containing a part of the linear electrode group based on the detection result, to execute a process for exporting the alternating magnetic fields from at least a portion of the linear electrode set a plurality of times and to use a plurality of result values ​​detected by at least a portion of the detection coil group as a result of the execution to derive a two-dimensional position of the indicator; and to update the linear electrode set according to the derived two-dimensional position. [2] The sensor device according to claim 1, wherein the two-dimensional position is a position including a position in a first direction in which linear electrodes included in the linear electrode group are lined up and a position in a second direction in which coils included in the detection coil group are lined up. [3] The sensor device of claim 1, wherein while the process of exporting the alternating magnetic fields from at least a portion of the linear electrode set is performed a plurality of times, the linear electrode set is not used to detect the alternating magnetic field generated by the indicator. [4] The sensor device according to claim 1, wherein the process of exporting the alternating magnetic fields from at least a part of the linear electrode set is a process of selecting a predetermined number of linear electrodes from a plurality of linear electrodes included in the linear electrode set, and supplying a first alternating current to a half of the predetermined number of linear electrodes and simultaneously supplying a second alternating current different from the first alternating current to the rest of the predetermined number of linear electrodes. [5] The sensor device according to claim 4, wherein the integrated circuit performs the process of exporting the alternating magnetic fields from at least a part of the linear electrode set a plurality of times while changing a combination of linear electrodes to which the first alternating current is supplied from the predetermined number of linear electrodes and linear electrodes to which the second alternating current is supplied from the predetermined number of linear electrodes. [6] The sensor device according to claim 1, wherein the process for generating the alternating magnetic fields in at least a part of the linear electrode set is a process of: selecting one of a plurality of linear electrodes included in the linear electrode set and supplying a first alternating current to one or more linear electrodes adjacent to each other on one side, and simultaneously supplying, via the selected linear electrode, a second alternating current different from the first alternating current to one or more linear electrodes adjacent to each other on another side. [7] The sensor device according to any one of claims 4 to 6, wherein the first alternating current and the second alternating current are generated to satisfy a relationship that phases of time derivatives of the first alternating current and the second alternating current are opposite. [8] A sensor device that detects an indicator, the sensor device comprising: a linear electrode group extending in parallel; a detection coil group crossing the linear electrode group; and an integrated circuit connected to the linear electrode group and the detection coil group, wherein the integrated circuit is configured to supply a first alternating current to one end in a longitudinal direction of one or more first linear electrodes in the linear electrode group and to supply a second alternating current to one end in the longitudinal direction of one or more second linear electrodes different from the one or more first linear electrodes in the linear electrode group, and the first alternating current and the second alternating current are generated to satisfy a relationship that phases of time derivatives of the first alternating current and the second alternating current are opposite. [9] Sensor device according to claim 8, wherein the relationship is that the second alternating current decreases with an increase in the first alternating current and the second alternating current increases with a decrease in the first alternating current. [10] The sensor device according to claim 8, wherein the relationship is that a potential at one end with respect to another end in the longitudinal direction of each of the one or more second linear electrodes increases with an increase in a potential of another end with respect to the one end in the longitudinal direction of each of the one or more first linear electrodes. [11] Sensor device according to claim 8, wherein the one or more first linear electrodes are a predetermined number of linear electrodes adjacent to each other on one side of a linear electrode selected from the linear electrode group, and the one or more second linear electrodes are the same number of linear electrodes adjacent to each other on another side of the one linear electrode. [12] The sensor device according to claim 8, wherein a potential of another end in the longitudinal direction of each of the one or more first linear electrodes and a potential of another end in the longitudinal direction of each of the one or more second linear electrodes are a potential at a midpoint of a potential generated by the first alternating current at one end of the one or more first linear electrodes and a potential generated by the second alternating current at one end of the one or more second linear electrodes. [13] The sensor device of claim 12, wherein when the potential of the one or more first linear electrodes is greater than the center point, the potential of the one or more second linear electrodes is smaller than the center point. [14] An integrated circuit connected to a linear electrode group extending in parallel and a detection coil group crossing the linear electrode group, the integrated circuit being configured to detect an indicator, the integrated circuit being further configured: sequentially export alternating magnetic fields from the linear electrode group, use the detection coil group to detect an alternating magnetic field generated by the indicator according to the alternating magnetic fields, and determine a linear electrode set containing part of the linear electrode group based on the detection result; to execute a process for exporting alternating magnetic fields from at least a portion of the linear electrode set a plurality of times and to use a plurality of result values ​​detected by at least a portion of the detection coil group as a result of the execution to derive a two-dimensional position of the indicator; and to update the linear electrode set according to the derived two-dimensional position. [15] An integrated circuit connected to a linear electrode group extending in parallel and a detection coil group crossing the linear electrode group, the integrated circuit being configured to to detect an indicator, the integrated circuit being further configured: supplying a first alternating current to one end in a longitudinal direction of one or more first linear electrodes in the linear electrode group and supplying a second alternating current to one end in the longitudinal direction of one or more second linear electrodes different from the one or more first linear electrodes in the linear electrode group, wherein the first alternating current and the second alternating current are generated to satisfy a relationship that phases of time derivatives of the first alternating current and the second alternating current are opposite. [16] A method for detecting an indicator using a linear electrode group extending in parallel and a detection coil group crossing the linear electrode group, the method comprising: a step of exporting, in sequence, alternating magnetic fields from the linear electrode group, using the detection coil group to detect an alternating magnetic field generated by the indicator according to the alternating magnetic fields, and determining a linear electrode set including part of the linear electrode group based on a detection result; a step of executing a process for exporting changing magnetic fields from at least a portion of the linear electrode set a plurality of times and using a plurality of result values ​​detected by at least a portion of the detection coil group as a result of the execution to derive a two-dimensional position of the indicator; and a step to update the linear electrode set according to the derived two-dimensional position. [17] A method for detecting an indicator using a linear electrode group extending in parallel and a detection coil group crossing the linear electrode group, the method comprising: a step of generating a first alternating current and a second alternating current that satisfy a relationship that phases of time derivatives of the first alternating current and the second alternating current are opposite; and a step of supplying the first alternating current to one end in a longitudinal direction of one or more first linear electrodes in the linear electrode group and supplying the second alternating current to the one end in the longitudinal direction of one or more second linear electrodes different from the one or more first linear electrodes in the linear electrode group.

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