SENSOR DEVICE, INTEGRATED CIRCUIT, AND METHOD FOR DETECTING AN INDICATOR - Patent application

Abstract

[Problem] To enable any increase in electric power consumption to be prevented while substituting Tx coils with linear electrodes. [Solution] This sensor device comprises a group of linear electrodes EL that extend in parallel to each other, a group of loop coils LCx that intersect the group of linear electrodes EL, and a sensor controller 31. The sensor controller 31: sequentially sends out an alternating magnetic field from the group of linear electrodes EL; detects, by using the group of loop coils LCx, an alternating magnetic field that is generated by an indicator in response to the aforementioned alternating magnetic field; determines a linear electrode set that is composed of some linear electrodes EL from the group of linear electrodes EL on the basis of the result of detection; executes, for a plurality of instances, a process for generating an alternating magnetic field in at least some linear electrodes in the set of linear electrodes; derives the two-dimensional position of the indicator using a plurality of result values detected by at least some loop coils LCx in the group of loop coils LCx as the result of each instance of execution; and updates the linear electrode set in accordance with the derived two-dimensional position.

Description

[Technical field]

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

[0002] The electromagnetic induction method (EMR method) is known as one of the methods for detecting the position of an electromagnetic induction pen on the panel surface of a tablet terminal or the like. A tablet terminal using the EMR method has a pen detection sensor (hereinafter referred to as the "EMR sensor") arranged on the panel surface, and a sensor controller connected to the EMR sensor. The EMR sensor is composed of multiple Tx coils arranged in a line in the y direction and multiple Rx coils arranged in a line in the x direction. The sensor controller detects the position of the electromagnetic induction pen by sequentially sending out alternating magnetic fields from the multiple Tx coils and receiving the reflected signals (hereinafter referred to as the "pen signals") sent by the electromagnetic induction pen at each Rx coil, and at the same time, receives the data sent by the electromagnetic induction pen.

[0003] Patent Document 1 discloses an example of an EMR sensor. In order to suppress price increases, the EMR sensor described in the document is configured to use a drive electrode (a linear electrode to which a drive signal for display is supplied) in the display device as a Tx coil and a signal line (a wiring to which an image signal is supplied) in the display device as an Rx coil. The generation of an alternating magnetic field by the drive electrodes is performed by selecting two drive electrodes by a selection signal, passing a current from one end to the other end of one drive electrode, and passing the same current from the other end to one end of the other drive electrode. In the document, the drive electrodes and signal lines in the display device are further used as touch electrodes for detecting fingers by a capacitive method. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6698386 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, in order to generate a magnetic field of the required magnitude, the Tx coil of an EMR sensor needs to pass a current with a larger amplitude than the drive signal for display, etc. If such a large current is passed through a linear electrode used as a substitute for a Tx coil, the power consumption increases because the DC resistance of the linear electrode is larger than that of a general Tx coil. Therefore, there was a need for a technology that can prevent an increase in power consumption while using a linear electrode as a substitute for a Tx coil.

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

[0007] Furthermore, as in the invention described in Patent Document 1, when an alternating magnetic field is generated by selecting two linear electrodes using a selection signal and passing a current from one end of one linear electrode to the other while passing the same current from the other end to one end of the other linear electrode, a phase shift occurs between the two linear electrodes, resulting in noise being superimposed on the magnetic field detected by the Rx coil, and improvement was needed.

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

[0009] A sensor device according to one aspect of the present invention is a sensor device for detecting an indicator, comprising: a group of linear electrodes extending parallel to each other, a group of detection coils intersecting the group of linear electrodes, and an integrated circuit connected to the group of linear electrodes and the group of detection coils, wherein the integrated circuit sequentially transmits alternating magnetic fields from the group of linear electrodes, detects the alternating magnetic field generated by the indicator in response to the alternating magnetic field using the group of detection coils, determines a linear electrode set consisting of a portion of the group of linear electrodes based on the results of the detection, and executes a process of transmitting an alternating magnetic field from at least a portion of the linear electrode set a plurality of times, derives a two-dimensional position of the indicator using a plurality of result values ​​detected by at least a portion of the group of detection coils as a result of each execution, and updates the linear electrode set in accordance with the derived two-dimensional position.

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

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

[0012] A sensor device according to another aspect of the present invention is a sensor device for detecting an indicator, comprising a group of linear electrodes extending parallel to each other, a group of detection coils intersecting the group of linear electrodes, and an integrated circuit connected to the group of linear electrodes and the group of detection coils, wherein the integrated circuit is configured to supply a first AC current to one longitudinal end of one or more first linear electrodes in the group of linear electrodes, while supplying a second AC current to the one longitudinal end of one or more second linear electrodes different from the first linear electrodes in the group of linear electrodes, and wherein the first AC current and the second AC current are generated so as to satisfy a relationship in which their respective time derivatives are in opposite phase to each other.

[0013] An integrated circuit according to another aspect of the present invention is an integrated circuit that is connected to a group of linear electrodes extending parallel to each other and a group of detection coils that intersect with the group of linear electrodes and detects an indicator, wherein a first AC current is supplied to one longitudinal end of one or more first linear electrodes in the group of linear electrodes, while a second AC current is supplied to one longitudinal end of one or more second linear electrodes in the group of linear electrodes that are different from the one or more first linear electrodes, and the first AC current and the second AC current are generated so as to satisfy a relationship in which their respective time derivatives are in opposite phase to each other.

[0014] A method according to another aspect of the present invention is a method for detecting an indicator using a group of linear electrodes extending parallel to each other and a group of detection coils intersecting the group of linear electrodes, the method including the steps of generating a first AC current and a second AC current whose time derivatives are in opposite phase to each other, and supplying the first AC current to one longitudinal end of one or more first linear electrodes in the group of linear electrodes, while supplying the second AC current to the one longitudinal end of one or more second linear electrodes different from the one or more first linear electrodes in the group of linear electrodes. Effect of the Invention

[0015] According to a sensor device, integrated circuit, and method for detecting an indicator according to one aspect of the present invention, once a linear electrode set is identified, the two-dimensional position of the indicator can be derived by supplying current only to a predetermined number of linear electrodes that constitute the linear electrode set, making it possible to prevent an increase in power consumption while using the linear electrodes as a substitute for a Tx coil.

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

[0017] [Figure 1] 1 is a diagram showing a configuration of a position detection system 1 according to a first embodiment of the present invention. [Diagram 2] 2 is a diagram showing an internal configuration of a switch unit 30 shown in FIG. 1. [Diagram 3] 4A to 4C are diagrams illustrating the state of the switch section 30 when the sensor controller 31 detects the position of a finger F. [Figure 4] 11 is a diagram showing the state of the switch section 30 when the sensor controller 31 detects the position of the electromagnetic induction pen P. FIG. [Diagram 5]11 is a diagram showing the state of the switch section 30 when the sensor controller 31 detects the position of the electromagnetic induction pen P. FIG. [Figure 6] 11 is a diagram showing the state of the switch section 30 when the sensor controller 31 detects the position of the electromagnetic induction pen P. FIG. [Figure 7] 1A is a diagram showing a method of supplying an AC current to a linear electrode EL in the present embodiment, and FIG. 1B is a diagram showing a method of supplying an AC current in a comparative example. [Figure 8] 7(a) is a diagram showing the results of measuring the current flowing through each linear electrode EL in the probing region PA1 shown in FIG. 7(a), and (b) is a diagram showing the results of measuring the current flowing through each linear electrode EL in the probing region PA2 shown in FIG. 7(b). [Figure 9] 13(a) and 13(b) are plots of measurement results of the phase difference θ, the amplitude A, and the amplitude B in the comparative example for a number of cases where the total parasitic capacitance is different. [Figure 10] FIG. 1A is a diagram showing waveforms of various signals related to the present embodiment, and FIG. 1B is a diagram showing a method of supplying various signals related to a comparative example. [Figure 11] 4 is a diagram illustrating a reception signal Rx supplied from a differential amplifier 30i to a sensor controller 31. FIG. [Figure 12] FIG. 2 is a diagram illustrating a received signal Rx according to a first comparative example. [Figure 13] FIG. 11 is a diagram illustrating a received signal Rx according to a second comparative example. [Figure 14] FIG. 13 is a diagram showing the results of simulating the level of the pen signal received by each of the loop coils LCx in the vicinity when the electromagnetic induction pen P is positioned above the loop coil LCxn. [Figure 15] 10 is a flow chart showing the overall flow of position detection of the electromagnetic induction pen P executed by the sensor controller 31. FIG. [Figure 16] 10 is a flow chart showing the overall flow of position detection of the electromagnetic induction pen P executed by the sensor controller 31. FIG. [Figure 17]10 is a flow chart showing the overall flow of position detection of the electromagnetic induction pen P executed by the sensor controller 31. FIG. [Figure 18] FIG. 11 is a diagram showing an internal configuration of a switch section 30 disposed in a position detection device 3 constituting a position detection system 1 according to a second embodiment of the present invention. [Figure 19] 11 is a diagram showing the state of the switch section 30 when the sensor controller 31 detects the position of the electromagnetic induction pen P. FIG. [Figure 20] 11 is a diagram showing the state of the switch section 30 when the sensor controller 31 detects the position of the electromagnetic induction pen P. FIG. [Figure 21] 11 is a diagram showing the state of the switch section 30 when the sensor controller 31 detects the position of the electromagnetic induction pen P. FIG. [Figure 22] FIG. 11 is a diagram showing an internal configuration of a switch section 30 disposed in a position detection device 3 constituting a position detection system 1 according to a third embodiment of the present invention. [Diagram 23] 11 is a diagram showing the state of the switch section 30 when the sensor controller 31 detects the position of the electromagnetic induction pen P. FIG. [Figure 24] 11 is a diagram showing the state of the switch section 30 when the sensor controller 31 detects the position of the electromagnetic induction pen P. FIG. [Diagram 25] 11 is a diagram showing the state of the switch section 30 when the sensor controller 31 detects the position of the electromagnetic induction pen P. FIG. [Figure 26] 25, and (d) to (f) are diagrams showing equivalent circuits when AC currents iA and iB are supplied to six linear electrodes ELm to ELm+5 by the methods shown in (a) to (c), respectively. [Figure 27] 10 is a flow chart showing the overall flow of position detection of the electromagnetic induction pen P executed by the sensor controller 31. FIG. [Figure 28] 10 is a flow chart showing the overall flow of position detection of the electromagnetic induction pen P executed by the sensor controller 31. FIG. [Figure 29]10 is a flow chart showing the overall flow of position detection of the electromagnetic induction pen P executed by the sensor controller 31. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0019] Fig. 1 is a diagram showing the configuration of a position detection system 1 according to a first embodiment of the present invention. As shown in the figure, the position detection system 1 is configured to have an electromagnetic induction pen P and a position detection device 3. Of these, the electromagnetic induction pen P is a pen (pointing body) compatible with position detection by the EMR method, and is configured to have an internal resonance circuit including a coil and a capacitor.

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

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

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

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

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

[0025] The drive circuit 30g generates an AC current i in response to an AC current Tx_EMR supplied from the sensor controller 31. A ,i B (see Figs. 4 to 6) and supplies it to the linear electrode EL via the switch 30a. The drive circuit 30g supplies AC current i A (first AC current) and the other two are supplied with AC current iB (second alternating current).

[0026] alternating current i A is a current generated by amplifying the AC current Tx_EMR using, for example, a buffer circuit. On the other hand, the AC current i B is the AC current i A The current is generated so that the time derivatives of the AC current i A As the increase in the AC current i B The decrease in AC current i A As the decrease in AC current i B It can be said that the increase in the AC current i A As the increment of the potential at one end of each of the linear electrodes EL that supplies the AC current i B It can be said that the relationship is such that the increment in potential at one end in the longitudinal direction of each of the one or more linear electrodes EL supplying current is greater than the increment at the other end.

[0027]

number

[0028] Typical AC current i that satisfies the relationship in equation (1) B is expressed by the following equation (2). Here, A is an arbitrary constant. When A=0, the AC current i B is the AC current i A In this case, the AC current i A and AC current i B On the other hand, A is AC current i A If it is greater than the maximum value of the AC current i A and AC current i B The AC current i AThe inverted signal of can be generated, for example, using an inverting buffer circuit, as shown in FIG.

[0029]

number

[0030] alternating current i A ,i B The potential at the other end of each linear electrode EL that receives the AC current i A The potential generated at one end of the linear electrode EL to which the AC current i B It is preferable that the potential be a midpoint between the potential generated at one end of the linear electrode EL to which the voltage A is supplied. When A=0, this potential is 0 (i.e., the ground potential).

[0031] The switch 30b is configured to supply a touch detection signal Tx_TP for detecting the position of a finger F to a plurality of linear electrodes EL, and is configured with a set of an input pin and an output pin provided for each linear electrode EL. The touch detection signal Tx_TP is supplied to each input pin from the sensor controller 31. Each output pin is connected to a corresponding linear electrode EL. The switch 30b plays a role of connecting each input pin to a corresponding output pin according to the control of the sensor controller 31.

[0032] The switch 30f is configured to switch the other end of the linear electrode EL in the x-direction (longitudinal direction) between a state in which it is connected to the potential of the midpoint described above and a floating state in which it is not connected anywhere. Fig. 2 shows a case in which the potential of the midpoint described above is the ground potential, and in this case, the switch 30f is configured to have a set of an input pin and a ground pin provided for each linear electrode EL, as shown in Fig. 2. The following description will be continued on the assumption that the potential of the midpoint described above is the ground potential.

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

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

[0035] Specifically, the switch 30c includes an input pin provided at each end of the loop coil LCx and four output pins provided for each input pin. The switch 30c plays a role of connecting each input pin to one of the corresponding four output pins according to the control of the sensor controller 31.

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

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

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

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

[0040] The host processor 32 performs processes such as moving a cursor displayed on the display surface and generating stroke data indicating the trajectory of the electromagnetic induction pen P or a finger on the touch surface, using the position and data supplied from the sensor controller 31. With regard to the stroke data, the host processor 32 also performs processes such as rendering and displaying the generated stroke data, generating and recording digital ink including the generated stroke data, and transmitting the generated digital ink to an external device in response to a user instruction.

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

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

[0043] The specific content of the touch detection signal Tx_TP generated by the sensor controller 31 can be expressed by a matrix A shown in the following formula (3). The matrix A is a square matrix having a plurality of rows that correspond one-to-one to the plurality of linear electrodes EL. Each element of the matrix A (A 11 The left side of the subscript attached to each of the linear electrodes EL (e.g., A, B, C, D, E, F, G, H, I, I, L) indicates the order of output from the sensor controller 31, and the right side indicates the serial number of the linear electrodes EL. M is the total number of linear electrodes EL. The specific value of each element is either "1" or "-1". Matrix A is preferably an orthogonal matrix, but does not have to be an orthogonal matrix.

[0044]

number

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

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

[0047] Here, the m-th linear electrode EL m and the nth loop coil LCx n The capacitance formed between mn In this case, the partial touch detection signal Tx_TP corresponding to the x-th column of the matrix A is supplied to each linear electrode EL, and the n-th loop coil LCx n is connected to the operational amplifier 30j, the reception signal Rx_TP supplied from the operational amplifier 30j to the sensor controller 31 has a value expressed by the following equation (4).

[0048]

number

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

[0050]

number

[0051] The sensor controller 31 performs the calculation shown on the left side of the following equation (6) on this vector b to obtain the capacitance C mn However, the matrix A shown in equation (6) is -1 is the inverse matrix of matrix A. As shown in equation (6), -1 By multiplying the matrix by , the unit matrix I is obtained. Therefore, the sensor controller 31 performs this calculation to obtain the n-th loop coil LCx n For each linear electrode EL m The capacitance C of the intersection with mn This means that the above rights can be acquired separately.

[0052]

number

[0053] The sensor controller 31 executes a calculation similar to that of the equation (6) for each loop coil LCx to obtain the capacitance C mn Then, the sensor controller 31 calculates each of the derived capacitances C mn Based on the distribution of the above on the touch surface, the position (two-dimensional position) of the finger F is derived. Specifically, the position corresponding to the peak of the distribution may be derived as the position of the finger F.

[0054] 4 to 6 are diagrams showing the state of the switch section 30 when the sensor controller 31 detects the position of the electromagnetic induction pen P. As shown in these figures, the sensor controller 31 detects the position of a single linear electrode EL m Two adjacent linear electrodes ELm-1 ,EL m-2 (First linear electrode) is supplied with an AC current i A is supplied to the two adjacent linear electrodes EL m+1 ,EL m+2 (Second linear electrode) AC current i B The sensor controller 31 controls the switch 30a so that each input pin is connected to a corresponding ground pin, thereby grounding the other end of each linear electrode EL in the x direction.

[0055] This control causes the linear electrode EL m A pseudo coil is formed with the center at the touch surface (especially the linear electrode EL m In the following, the generation of an alternating magnetic field in this way is referred to as a "linear electrode EL m The sensor controller 31 outputs an alternating magnetic field to each of the linear electrodes EL in order, except for the four linear electrodes EL located at both ends of the entire linear electrodes EL. m By executing the same process as above, the linear electrodes EL are configured to sequentially emit the same alternating magnetic field.

[0056] In order to detect the position of the electromagnetic induction pen P over the entire touch surface, it is preferable that the four linear electrodes EL that are excluded from the above process are disposed outside the touch surface. m Although an alternating current is passed through two linear electrodes EL on each side, it is sufficient to pass an alternating current through a predetermined number of linear electrodes EL, which are one or more, and for example, it is also possible to pass an alternating current through one linear electrode EL on each side, or three or more linear electrodes EL on each side.

[0057] As can be seen from the descriptions of FIGS. 4 to 6, the driving circuit 30g is disposed on one end side of each linear electrode EL in the longitudinal direction, and an AC current i A ,i Bare both supplied to one end (end on the same side) in the x direction (longitudinal direction) of the linear electrode EL. The effects achieved by adopting such a configuration will be described in detail below with reference to a comparative example.

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

[0059] FIG. 8(a) is a diagram showing the results of measuring the current flowing through each linear electrode EL in the probing region PA1 shown in FIG. 7(a), and FIG. 8(b) is a diagram showing the results of measuring the current flowing through each linear electrode EL in the probing region PA2 shown in FIG. 7(b). In each diagram, the horizontal axis represents time, and the vertical axis represents current value. In FIGS. 8(a) and (b), the linear electrodes EL m+1 ,EL m+2 8(a) and (b) show the case where the parasitic capacitance of the current path for each linear electrode EL (hereinafter referred to as the “total parasitic capacitance”) is 1800 pF.

[0060] Linear electrode EL mThe linear electrode EL can most efficiently emit an alternating magnetic field. m-1 ,EL m-2 The amplitude of the current flowing through the linear electrode EL m+1 ,EL m+2 The amplitude of the current flowing through the linear electrode EL m-1 ,EL m-2 and the linear electrode EL m+1 ,EL m+2 This is the case where the phase difference between the inverted signal of the current flowing through the linear electrode EL (phase difference θ shown in FIG. 8(b)) is 0°. As can be seen from FIG. 8(a), in this embodiment, A=B and θ=0°, which can be said to be an ideal state in terms of the transmission efficiency of the alternating magnetic field. On the other hand, as shown in FIG. 8(b), in the comparative example, A≠B and θ≠0° (specifically, about 32°). Therefore, according to this embodiment, compared to the comparative example, the linear electrode EL m It can be said that the alternating magnetic field can be efficiently transmitted from the

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

[0062] 10(a) is a diagram showing the waveforms of various signals related to this embodiment, and FIG. 10(b) is a diagram showing a method of supplying various signals related to a comparative example. In these figures, linear electrodes EL m-1,EL m-2 The waveform of the current flowing through the linear electrode EL m+1 ,EL m+2 4 shows the waveform of the current flowing through the electromagnetic induction pen P, the waveform (Pen signal) of the voltage generated inside the electromagnetic induction pen P (Pen resonant waveform), and the waveform of the received signal Rx_EMR detected by the loop coil LCx closest to the electromagnetic induction pen P.

[0063] First, referring to FIG. 10(b), the sensor controller 31 applies an AC current i to the linear electrode EL. A While the alternating magnetic field is being supplied (the "alternating magnetic field sending period" shown in the figure), a pen signal is generated inside the electromagnetic induction pen P, and the received signal Rx_EMR includes an alternating current i generated in the linear electrode EL. A It can be seen that a waveform similar to that shown in FIG. 1 appears. The waveform of the received signal Rx_EMR is formed by superimposing a voltage signal induced in the loop coil LCx by the alternating magnetic field sent from the linear electrode EL on a voltage signal induced in the loop coil LCx by the pen signal sent from the electromagnetic induction pen P. The sensor controller 31 supplies an AC current i A When the supply of the AC current i to the linear electrode EL is terminated, the voltage signal induced by the AC magnetic field sent from the linear electrode EL disappears, so only the voltage signal induced by the pen signal remains in the received signal Rx_EMR. A The waveform of the reception signal Rx_EMR after the supply of the signal Rx_EMR is completed is the same as the waveform of the pen signal. Therefore, the sensor controller 31 according to the comparative example sets the period after the "alternating magnetic field transmission period" as a "position derivation / data reception period" in which the position of the electromagnetic induction pen P is derived and the data transmitted by the electromagnetic induction pen P is received, and based on the reception signal Rx_EMR acquired during this period, the position of the electromagnetic induction pen P is derived and the data transmitted by the electromagnetic induction pen P is received.

[0064] On the other hand, in FIG. 10(a), the waveform of the reception signal Rx_EMR is the same as that of the pen signal over the entire period including the alternating magnetic field transmission period. This is because, as shown in FIG. 8(a), the linear electrode ELm-1 ,EL m-2 and the linear electrode EL m+1 ,EL m+2 Since there is no phase shift between the current flowing through the linear electrode EL m This is because the voltage signal induced in the loop coil LCx by the alternating magnetic field sent from the loop coil LCx is not superimposed on the receiving signal Rx_EMR. In other words, according to this embodiment, it can be said that the noise superimposed on the alternating magnetic field detected by the loop coil LCx is reduced. The sensor controller 31 according to this embodiment makes use of this effect and also uses the "alternating magnetic field sending period" as a "position derivation period" for deriving the position of the electromagnetic induction pen P, and derives the position of the electromagnetic induction pen P based on the voltage signal appearing in the loop coil LCx during this period. Therefore, according to this embodiment, the period for receiving the pen signal for deriving the position of the electromagnetic induction pen P can be secured longer than in the comparative example, so that it is possible to derive the position of the electromagnetic induction pen P with higher accuracy than in the comparative example.

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

[0066] Returning to FIG. 4 to FIG. 6, the sensor controller 31 detects the linear electrode EL mWhile transmitting an alternating magnetic field from the sensor 30, the switch 30d is kept in a connected state, three adjacent loop coils LCx are treated as one set, and each time, a process of controlling the switch 30c is performed to select each set in turn, so that the three loop coils LCx constituting the selected set are connected in series to the differential amplifier 30i in three different connection configurations with different connection polarities. Through this process, the differential amplifier 30i detects a result value indicating the level of the pen signal based on the potential between both ends of the composite coil consisting of the three loop coils LCx connected in series, and outputs the result value to the sensor controller 31 as a received signal Rx_EMR.

[0067] 4 to 6 show the above three connection configurations. Specifically, in the example of FIG. 4, when viewed from the non-inverting input terminal of the differential amplifier 30i, the loop coil LCx n-1 Connect it counterclockwise (marked "-1" in the diagram), then connect the loop coil LCx n Connect clockwise (marked "1" in the diagram), and finally loop coil LCx n+1 5, the loop coil LCx n-1 Connect in a clockwise direction, then loop coil LCx n Connect counterclockwise, and finally loop coil LCx n+1 In the example of FIG. 6, the loop coil LCx n-1 Connect counterclockwise, then loop coil LCx n Connect counterclockwise, and finally loop coil LCx n+1 are connected in a clockwise direction.

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

[0069] Referring to FIG. 11, the pen signal received during the pen signal detection period T1 is input to the loop coil LCx n and loop coil LCx n-1 ,LCx n+1 This is because, as described above, the loop coils LCx n clockwise, loop coil LCx n-1 ,LCx n+1 As a result, the sensor controller 31 detects the linear electrode EL m When an alternating magnetic field is generated at the loop coil LCx n-1 ~LCx n+1 The level of the pen signal received by m,n-1 ~E m,n+1 As shown in FIG. 11, during the pen signal detection period T1, the reception signal Rx_EMR (result value) supplied from the differential amplifier 30i to the sensor controller 31 is −E m,n-1 +E m,n -E m,n+1 The same is true for the pen signal detection periods T2 and T3, which are expressed as +E m,n-1 -E m,n -E m,n+1 , -E m,n-1 -E m,n +E m,n+1 This can be expressed as:

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

[0071]

number

[0072] The sensor controller 31 calculates the vector d series By performing the calculation shown on the left side of the following equation (8), the level E m,n-1 ~E m,n+1 However, the matrix F shown in equation (8) is obtained separately. -1 is the inverse matrix of the matrix F, and therefore the calculation shown on the left side of the formula (8) is a restoration calculation according to the connection polarity of the loop coil LCx in each of the above-mentioned connection configurations. -1 Since multiplying by , results in a unit matrix I, the sensor controller 31 performs this restoration calculation to obtain the m-th linear electrode EL m When an alternating magnetic field is sent from the loop coil LCx n-1 ~LCx n+1 The level of the pen signal received at each m,n-1 ~E m,n+1 This means that the above rights can be acquired separately.

[0073]

number

[0074] The sensor controller 31 executes a calculation similar to that of the formula (8) for each set of the loop coil LCx to obtain the m-th linear electrode EL mThe sensor controller 31 also detects the level of the pen signal received by each of the plurality of loop coils LCx when an alternating magnetic field is transmitted from the linear electrode EL m By performing the same process while changing m The sensor controller 31 obtains the level of the pen signal received by each of the loop coils LCx when an alternating magnetic field is transmitted from each of the loop coils LCx. The sensor controller 31 then derives the position (two-dimensional position) of the electromagnetic induction pen P based on the distribution of the levels of the pen signals thus obtained within the touch surface. Specifically, the position corresponding to the peak of the distribution may be derived as the position of the electromagnetic induction pen P. Details of the detection of the position of the electromagnetic induction pen P executed by the sensor controller 31 will be described in more detail later with reference to Figs. 15 to 17.

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

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

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

[0078] FIG. 14 shows that the electromagnetic induction pen P is a loop coil LCx n 13 is a diagram showing the results of simulating the levels of the pen signals received by the loop coils LCx in the vicinity thereof (levels after separation in the case of separate acquisition) when the pen signal is located on the upper side of the sensor controller 31. The diagram shows the results of the present embodiment (FIG. 11), the first comparative example (FIG. 12), and the second comparative example (FIG. 13). As shown in the diagram, the pen signal receiving method according to the present embodiment has the effect of significantly increasing the pen signal receiving level compared to the first and second comparative examples. This is because the pen signal receiving method according to the present embodiment has a pen signal detection period that can be used to obtain the pen signal received by each loop coil LCx that is three times longer than the first and second comparative examples. Here, as will be described later, when the pen signal detection period of the pen signal in the sensor controller 31 becomes N times longer, the level of the received pen signal becomes N times longer, while the level of the received noise becomes N times longer. 1 / 2 Therefore, it can be said that the pen signal receiving method according to this embodiment makes it possible to improve the S / N ratio of the pen signal received by the sensor controller 31.

[0079] In addition, according to the pen signal receiving method of this embodiment, the pen signals received by the multiple loop coils LCx are simultaneously received by one receiving circuit during each of the multiple pen signal detection periods, and the received signal Rx_EMR can be separated into components for each loop coil LCx, so there is no need to lengthen the pen signal transmission period to improve the S / N ratio, and there is no need to add additional receiving circuits to receive pen signals in parallel from the multiple loop coils LCx. Therefore, according to the pen signal receiving method of this embodiment, it can be said that it is possible to improve the S / N ratio of the pen signal received by the sensor controller 31 without reducing the frequency of position detection and without increasing the circuit scale of the sensor controller 31.

[0080] Hereinafter, when the pen signal detection period of the sensor controller 31 becomes N times, the noise level becomes N 1 / 2 We will now explain in detail why the figure remains at double.

[0081] The received signal Rx acquired during the k-th pen signal detection period is X k Let the variance be V(X k ), then due to the additivity of the variance, N reception signals X1 to X2 acquired in the 1st to Nth pen signal detection periods are expressed as N The variance V of the signal obtained by adding TOTAL is expressed as the sum of the variances of the received signal Rx in each pen signal detection period, as shown in the following equation (9).

[0082]

number

[0083] If we focus only on the noise component contained in the received signal Rx, we can assume that the noise will be the same value during all pen signal detection periods. Therefore, the variance of the sum signal V TOTAL is further expressed as the following equation (10): where V and σ are the variance and standard deviation in each pen signal detection period, respectively.

[0084]

number

[0085] The amount of noise that appears in the sum signal is the standard deviation of the sum signal, σ TOTAL From equation (10), this standard deviation σ TOTAL is expressed by the following equation (11), so when the pen signal detection period of the sensor controller 31 becomes N times, the noise level becomes N 1 / 2 It is understood that the number of

[0086]

number

[0087] Next, the position detection of the electromagnetic induction pen P executed by the sensor controller 31 will be described in more detail with reference to a flow chart.

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

[0089] Next, the sensor controller 31 starts to emit an alternating magnetic field from the selected linear electrode EL (step S4). Specifically, by controlling the switch 30a, the alternating current i A(output terminal of the buffer circuit), and two adjacent linear electrodes EL on the other side of the selected linear electrode EL are connected to the output terminal of the driver circuit 30g via an AC current i B (output terminal of the inverting buffer circuit) of the drive circuit 30g, and starts supplying the AC current Tx_EMR to the drive circuit 30g. Then, the sensor controller 31 temporarily stores the level of the reception signal Rx_EMR output from the differential amplifier 30i in response to the alternating magnetic field sent out in step S4 (step S5). The level of the reception signal Rx_EMR stored here may be, for example, the maximum value in the entire position derivation period shown in Fig. 10(a) (including the position derivation period which is the alternating magnetic field sending period and the position derivation period after the alternating magnetic field sending period), or may be the maximum value in the position derivation period after the alternating magnetic field sending period.

[0090] Next, the sensor controller 31 judges whether or not the processes of steps S4 to S5 have been tried in all the connection topologies (step S6). Specifically, it judges whether or not the processes of steps S4 to S5 have been tried in all the three connection topologies shown in Figs. 4 to 6. If the sensor controller 31 judges that the processes have not been tried, it controls the switches 30c to 30e to connect the three selected loop coils LCx to the differential amplifier 30i in the next connection topologies (for example, the connection topologies shown in Fig. 5 after the connection topologies shown in Fig. 4, and the connection topologies shown in Fig. 6 after the connection topologies shown in Fig. 5) (step S7), and returns to step S4.

[0091] On the other hand, if it is determined in step S6 that a trial has been performed, the sensor controller 31 derives the level of the pen signal for each loop coil LCx based on the levels of the multiple reception signals Rx_EMR temporarily stored by multiple trials in step S5 (step S8). Specifically, the restoration calculation shown in the above-mentioned formula (8) is performed.

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

[0093] The sensor controller 31, which has determined that the process is completed in step S11, determines whether or not a pen signal has been detected based on the level of the pen signal for each combination of the linear electrode EL and the loop coil LCx obtained by repeating step S8 (step S13 in FIG. 16). In one example, the result of this determination is positive if a level exceeding a predetermined value exists, and negative otherwise.

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

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

[0096] Next, the sensor controller 31 selects the endmost one of the linear electrodes EL to be selected (step S16), and then selects three loop coils LCx from the end of the loop coils LCx to be selected, and controls the switches 30c to 30e to connect the selected three loop coils LCx to the differential amplifier 30i in a first connection form (for example, the connection form shown in FIG. 4) (step S17).

[0097] 17, the sensor controller 31 next performs the same processes as steps S4 to S13 in FIG. 15 and FIG. 16 (steps S18 to S27). However, the process here differs from the process of steps S4 to S14 in that while only the level of the reception signal Rx_EMR is temporarily stored in step S5, a series of digital values ​​(obtained by sampling) constituting the reception signal Rx_EMR is also stored in step S19, while it is determined whether or not the selection of all loop coils LCx has been completed in step S9, it is determined whether or not the selection of all loop coils LCx determined as selection targets in step S15 has been completed in step S23, and while it is determined whether or not the selection of all linear electrodes EL determined as selection targets in step S11 has been completed in step S1, it is determined whether or not the selection of all linear electrodes EL determined as selection targets in step S15 has been completed in step S25. Note that the series of digital values ​​stored in step S19 may only be those for the position derivation and data reception period shown in FIG. 10(a).

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

[0099] By adopting the above-described processing, according to the sensor controller 31 of this embodiment, after the linear electrode set is identified in step S15 of FIG. 16, it becomes possible to update the two-dimensional position of the electromagnetic induction pen P by emitting an alternating magnetic field only from a predetermined number of linear electrodes EL that constitute the linear electrode set, thereby making it possible to prevent an increase in power consumption while using the linear electrodes EL as a substitute for the Tx coil.

[0100] As described above, according to the position detection system 1 of this embodiment, once the linear electrode set has been identified, it is possible to update the two-dimensional position of the electromagnetic induction pen P by emitting an alternating magnetic field only from a predetermined number of linear electrodes EL that constitute the linear electrode set, thereby making it possible to prevent an increase in power consumption while using the linear electrodes EL as a substitute for the Tx coil.

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

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

[0103] Furthermore, according to the position detection system 1 of this embodiment, both an EMR sensor and a touch sensor (a sensor for detecting a touch by a finger F using a capacitive method) can be realized by a pair of linear electrodes EL arranged in the y direction and a pair of loop coils LCx arranged in the x direction. This makes it possible to realize a lighter and more cost-effective position detection device compared to a case in which an EMR sensor and a touch sensor are separately provided in a single position detection device.

[0104] Furthermore, according to the position detection system 1 of this embodiment, since the differential amplifier 30i is used to receive the reception signal Rx_EMR, it is possible to suppress the variation in the level of the pen signal even if the resistance value varies between the loop coils LCx. This is particularly effective when the loop coils LCx are made of a high impedance material such as a metal mesh.

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

[0106] To generalize, when k loop coils LCx are connected in series to the differential amplifier 30i at the same time (i.e., when the sensor controller 31 selects adjacent k loop coils LCx as one set while an alternating magnetic field is being sent from any of the linear electrodes EL, and controls the switch 30c each time so that the k loop coils LCx constituting the selected set are connected in series to the differential amplifier 30i in k different connection configurations with different connection polarities), if the rank of a matrix F (a matrix with k rows and k columns) as a coefficient matrix of the simultaneous equations expressed by the following equation (12) is equal to k, the connection configuration of the loop coils LCx in each pen signal detection period can be determined based on the matrix F. In other words, if each column vector of the matrix F is linearly independent of each other, the connection configuration of the loop coils LCx in each pen signal detection period can be determined based on the matrix F. This is because the equation (12) always has a solution in any case.

[0107]

number

[0108] In this embodiment, the inverse matrix F -1 However, it is also possible to perform the restoration calculation using a matrix other than the inverse matrix. series is obtained, an example of a restoration operation using the matrix F itself as a matrix that is not the inverse matrix of the matrix F will be described.

[0109] In this example, first, the restoration matrix F and the level -E of the received signal Rx during the pen signal detection periods T1 to T3 are calculated. m,n-1 +E m,n -E m,n+1 , +E m,n-1 -E m,n -E m,n+1 , -E m,n-1 -E m,n +E m,n+1Using these, the level of the received signal Rx corresponding to the case where all columns of the matrix F are 1 is derived. Specifically, the simultaneous equations shown in the following equation (13) are solved to find a, b, and c, and a+b+c is 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 +E m,n-1 +E m,n +E m,n+1 It becomes.

[0110]

number

[0111] Next, as shown in the following formula (14), a column whose elements all have the value 1 is added to the beginning of the matrix F, and the value is +E m,n-1 +E m,n +E m,n+1 Let the row of vector d be series Add matrix F to the beginning of vector d series When multiplied by , a result is obtained that is a linear amplification (specifically, four times) of the calculation result of equation (8).

[0112]

number

[0113] In this way, the inverse matrix F of the matrix F -1 When performing the restoration calculation using a matrix other than F, it is necessary to derive the level of the received signal Rx corresponding to the case where all columns of the matrix F are 1. However, the inverse matrix F of the matrix F is -1 As in the case of performing the reconstruction operation using level E m,n-1 ~E m,n+1 can be obtained separately.

[0114] In addition, in equation (14), the result of the calculation in equation (8) is amplified by four times, but this is desirable because it leads to improved accuracy in the subsequent calculations. -1The same can be said for the case where the restoration calculation is performed using the following. A specific example will be described below.

[0115] Vector d when matrix F is a 4×4 Walsh code series is expressed by the following equation (15): where vector e is a vector indicating the level of the pen signal received by each of the four loop coils LCx.

[0116]

number

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

[0118]

number

[0119] Therefore, when performing the restoration operation of the vector e, the inverse matrix F -1 By multiplying by 4, the inverse matrix F -1 It is possible to obtain a vector having four times the levels of the original vector e while still performing the restoration operation by the method described above.

[0120]

number

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

[0122] FIG. 18 is a diagram showing an internal configuration of a switch section 30 disposed in a position detection device 3 constituting a position detection system 1 according to this embodiment. The switch section 30 according to this embodiment differs from the switch section 30 according to the first embodiment in that the wiring section 30h does not have the wirings L1 and L2, the switch 30c does not have output pins corresponding to the wirings L1 and L2, and an operational amplifier 30n is provided instead of the differential amplifier 30i. The switch 30d according to this embodiment serves to connect the wiring L4 to the input terminal of the operational amplifier 30n and the wiring L3 to the ground terminal, respectively, according to the control of the sensor controller 31. The sensor controller 31 according to this embodiment also differs from the sensor controller 31 according to the first embodiment in that three loop coils LCx are connected to the operational amplifier 30n in parallel, not in series, in order to detect the position of the electromagnetic induction pen P. In other respects, the position detection system 1 according to this embodiment is similar to the position detection system 1 according to the first embodiment, so the following description will focus on the differences from the position detection system 1 according to the first embodiment.

[0123] 19 to 21 are diagrams showing the state of the switch section 30 when the sensor controller 31 according to the present embodiment detects the position of the electromagnetic induction pen P. The sensor controller 31 according to the present embodiment detects the position of the linear electrode EL m While transmitting an alternating magnetic field from the sensor 30, three adjacent loop coils LCx are treated as one set, and each time, a process of controlling the switch 30c is performed to select each set in turn, so that the three loop coils LCx constituting the selected set are connected in parallel to the operational amplifier 30n in three different connection configurations with different connection polarities. Through this process, the operational amplifier 30n detects a result value indicating the level of the pen signal based on the potential (potential with respect to the ground terminal) of one end of the composite coil made up of the three loop coils LCx connected in parallel, and outputs the result value to the sensor controller 31 as a received signal Rx_EMR.

[0124] 19 to 21 show the above three connection configurations. To be more specific, in the example of FIG. 19, when viewed from the input terminal of the operational amplifier 30n, the loop coil LCx n-1 ,LCx n+1 Connect counterclockwise (indicated as "-1" in the diagram), and loop coil LCx n In the example of FIG. 20, the loop coil LCx n-1 Connect in a clockwise direction and loop coil LCx n ,LCx n+1 In the example of FIG. 21, the loop coil LCx n-1 ,LCx n Connect counterclockwise and loop coil LCx n+1 are connected in a clockwise direction.

[0125] As a result of the above-mentioned connection, the reception signal Rx_EMR supplied from the operational amplifier 30n to the sensor controller 31 is expressed by the vector d parallel The level E shown in equation (18) is expressed as m,n-1 ~E m,n+1 The meaning of is as explained in the first embodiment. As shown in the last line of the formula (18), the vector d parallel Also, the vector d series Similarly, a 3 × 3 matrix F indicating the connection polarity during each pen signal detection period and a level E m,n-1 ~E m,n+1 This can be transformed into a product with a vector representing

[0126]

number

[0127] Vector d parallel is the vector d series As can be seen from the fact that the vector d parallel Inverse matrix F of matrix F-1 By multiplying the loop coil LCx n-1 ~LCx n+1 The level of the pen signal received at each m,n-1 ~E m,n+1 can be separately acquired. Therefore, the pen signal receiving method according to this embodiment can also obtain the same effect as that of the first embodiment. Specifically, it is possible to prevent an increase in power consumption while substituting the Tx coil with the linear electrode EL, and also to reduce noise superimposed on the alternating magnetic field detected by the Rx coil (loop coil LCx) when substituting the Tx coil with the linear electrode EL. Furthermore, it is possible to improve the S / N ratio of the pen signal received by the sensor controller 31 without decreasing the frequency of position detection and without increasing the circuit scale of the sensor controller 31. However, in this regard, when multiple loop coils LCx are connected in parallel, the inductance is smaller than when they are connected in series, so that in this embodiment, the level of the pen signal is smaller than that of the first embodiment. Therefore, it can be said that the effect of improving the S / N ratio of the pen signal is higher in the first embodiment than in this embodiment.

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

[0129] FIG. 22 is a diagram showing an internal configuration of the switch unit 30 disposed in the position detection device 3 constituting the position detection system 1 according to this embodiment. For simplicity, the figure shows only five loop coils LCx (loop coils LCx n-2 ~LCx n+2 ), six linear electrodes EL (linear electrodes EL m ~EL m+5 ) is shown in the figure. This also applies to Figs. 23 to 25 shown later.

[0130] The switch section 30 according to this embodiment differs from the switch section 30 according to the second embodiment in that it has a switch 30k instead of the switch 30a and a drive circuit 30m instead of the drive circuit 30g. In addition, the sensor controller 31 according to this embodiment has six linear electrodes EL m ~EL m+5 30n at the same time, while simultaneously supplying AC current to the operational amplifier 30n, and only one loop coil LCx is connected to the operational amplifier 30n at the same time. In other respects, the position detection system 1 according to this embodiment is similar to the position detection system 1 according to the second embodiment, so the following description will focus on the differences from the position detection system 1 according to the second embodiment.

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

[0132] The drive circuit 30m drives the above-mentioned AC current i in response to the AC current Tx_EMR supplied from the sensor controller 31. A ,i B and supplies it to each linear electrode EL via the switch 30k. The drive circuit 30m supplies an AC current i A and the other supplies AC current i B The device is configured to supply

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

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

[0135] 26(a) to 26(c) are diagrams each showing a method of supplying an AC current in each of the methods shown in FIG. 23 to FIG. 25. Also, FIG. 26(d) to 26(f) are diagrams each showing a method of supplying an AC current to six linear electrodes ELm ~EL m+5 AC current i A ,i B As shown in these figures, the linear electrode EL m+k (k is 0, 1, or 2) and linear electrode EL m+k+3 When AC currents whose time derivatives are in opposite phase to each other are applied to the linear electrode EL m+k+1 ,EL m+k+2 Regardless of the current flowing through the linear electrode EL m+k and the linear electrode EL m+k+3 In the following, this loop coil is referred to as a "pseudo loop coil PLC", and in particular, the linear electrode EL m+k ,EL m+k+3 The pseudo loop coil PLC is composed of the m+k " Pseudo Loop Coil PLC m+k The connection polarity of the linear electrode EL m+k AC current i A and a linear electrode EL m+k+3 AC current i B (indicated as "-" in the figure) and when a linear electrode EL m+k AC current i B and a linear electrode EL m+k+3 AC current i A (indicated as "+" in the diagram) is the opposite.

[0136] Linear electrode EL m+k AC current i A and a linear electrode EL m+k+3 AC current i B When supplying the loop coil LCx n The level of the pen signal received by E m+k,n When the AC current shown in FIG. 26(a) is supplied, the reception signal Rx_EMR (result value) supplied from the operational amplifier 30n to the sensor controller 31 is expressed as -E m,n +E m+1,n -E m+2,nThe same applies to the case where the AC current is supplied as shown in FIG. 26(b) and (c), and E m,n -E m+1,n -E m+2,n , -E m,n -E m+1,n +E m+2,n When this is expressed in vector form, it becomes the vector d tx And this vector d tx is the above-mentioned vector d series or vector d parallel Similarly, the 3 × 3 matrix F indicates the connection polarity of the pseudo loop coil PLC, and the level E m,n ~E m+2,n This can be transformed into a product with a vector representing

[0137]

number

[0138] Vector d tx is the vector d series or vector d parallel As can be seen from the fact that the vector d tx Inverse matrix F of matrix F -1 By multiplying by m ~PLC m+2 The level E of the pen signal received when an alternating magnetic field is sent from each of m,n ,E m+1,n ,E m+2,n According to the method of supplying alternating current in this embodiment, the length of the period during which an alternating magnetic field is output from each of the three pseudo loop coils PLC is three times longer than when an alternating magnetic field is output from each of the three pseudo loop coils PLC individually, so the level of the received pen signal is three times higher, while the level of the received noise is three times lower. 1 / 2Therefore, it can be said that the AC current supplying method according to this embodiment also makes it possible to improve the S / N ratio of the pen signal received by the sensor controller 31.

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

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

[0141] Next, the sensor controller 31 starts to transmit an alternating magnetic field from the selected linear electrodes EL (step S32). Specifically, the sensor controller 31 starts to supply an alternating current Tx_EMR to the driving circuit 30m. As a result, an alternating current i A ,i B As a result, the pseudo loop coil PLC described above is formed and an alternating magnetic field is sent out. After that, the sensor controller 31 temporarily stores the level of the reception signal Rx_EMR output from the operational amplifier 30n in response to the alternating magnetic field sent out in step S32 (step S33). The specific content of the level stored here may be the same as that stored in step S5 of FIG.

[0142] Next, the sensor controller 31 judges whether or not the processes of steps S32 to S33 have been tried in all the connection configurations (step S34). Specifically, the sensor controller 31 judges whether or not the processes of steps S32 to S33 have been tried in all the three connection configurations shown in Figs. 23 to 25. If the sensor controller 31 judges that the processes have not been tried, the sensor controller 31 controls the switch 30k to connect the six selected linear electrodes EL to the drive circuit 30m in the next connection configuration (for example, the connection configuration shown in Fig. 23 is followed by the connection configuration shown in Fig. 24, and the connection configuration shown in Fig. 24 is followed by the connection configuration shown in Fig. 25) (step S35), and returns to step S32.

[0143] On the other hand, if it is determined in step S34 that a trial has been performed, the sensor controller 31 derives the level of the pen signal for each pseudo loop coil PLC based on the levels of the multiple reception signals Rx_EMR temporarily stored by multiple trials in step S5 (step S36). tx Inverse matrix F of matrix F -1 A multiplication operation (restoration operation) is performed.

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

[0145] The sensor controller 31, which has determined that the process is completed in step S39, determines whether or not a pen signal has been detected based on the level of the pen signal for each combination of the pseudo loop coil PLC and the loop coil LCx obtained by repeating step S36 (step S41 in FIG. 28). In one example, the result of this determination is positive if a level exceeding a predetermined value exists, and negative otherwise.

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

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

[0148] Next, the sensor controller 31 selects the endmost one of the loop coils LCx to be selected, and connects it to the operational amplifier 30n by controlling the switch 30c (step S44).The sensor controller 31 also selects six end linear electrodes EL from the linear electrodes EL to be selected, and connects the selected six linear electrodes EL to the drive circuit 30m in a first connection form (for example, the connection form shown in FIG. 23) by controlling the switch 30k (step S45).

[0149] 29, the sensor controller 31 next performs the same processes as steps S32 to S41 in Fig. 27 and Fig. 28 (steps S46 to S55). However, the processes here differ from the processes in steps S32 to S41 in that while only the level of the reception signal Rx_EMR is temporarily stored in step S33, a series of digital values ​​(obtained by sampling) constituting the reception signal Rx_EMR is also stored in step S47, while it is determined in step S37 whether or not the selection of all linear electrodes EL has been completed, it is determined in step S51 whether or not the selection of all linear electrodes EL determined in step S43 as the selection target has been completed, and while it is determined in step S39 whether or not the selection of all loop coils LCx has been completed, it is determined in step S53 whether or not the selection of all loop coils LCx determined in step S43 as the selection target has been completed.

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

[0151] By adopting the above-described processing, according to the sensor controller 31 of this embodiment, after the linear electrode set is identified in step S43 of FIG. 28, it becomes possible to update the two-dimensional position of the electromagnetic induction pen P by emitting an alternating magnetic field only from a predetermined number of linear electrodes EL that constitute the linear electrode set, thereby making it possible to prevent an increase in power consumption while using the linear electrodes EL as a substitute for the Tx coil.

[0152] As described above, even with the position detection system 1 of this embodiment, once a linear electrode set has been identified, it is possible to update the two-dimensional position of the electromagnetic induction pen P by emitting an alternating magnetic field only from a predetermined number of linear electrodes EL that constitute the linear electrode set, thereby making it possible to prevent an increase in power consumption while using the linear electrodes EL as a substitute for the Tx coil.

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

[0154] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and it goes without saying that the present invention can be embodied in various forms without departing from the spirit of the present invention.

[0155] For example, in the first embodiment, an example was described in which the reception signal Rx_EMR is generated based on the potential between both ends of a composite coil consisting of three loop coils LCx connected in series, and in the second embodiment, an example was described in which the reception signal Rx_EMR is generated based on the potential at one end (potential with respect to the ground terminal) of a composite coil consisting of three loop coils LCx connected in parallel. However, when three loop coils LCx are connected in series, the reception signal Rx_EMR may be generated based on the potential at one end (potential with respect to the ground terminal) of the composite coil consisting of the three loop coils LCx, and when three loop coils LCx are connected in parallel, the reception signal Rx_EMR may be generated based on the potential between both ends of the composite coil consisting of the three loop coils LCx.

[0156] In the first and second embodiments, an example has been described in which three adjacent loop coils LCx are used as one set to detect the position of the electromagnetic induction pen P, but two adjacent loop coils LCx may be used as one set, or four or more adjacent loop coils LCx may be used as one set. Alternatively, all loop coils LCx may be used as one set. When n (n≧2) loop coils LCx are used as one set, the matrix F is an n×n matrix.

[0157] In the first and second embodiments, the switch 30c is used to change the mutual connection of the multiple loop coils LCx while generating the reception signal Rx_EMR. However, the reception signal Rx_EMR may be generated while changing the connection between each loop coil LCx and the arithmetic circuit. For example, in the pen signal detection period T1 shown in FIG. n-1 ,LCx n+1 to the subtraction circuit, loop coil LCx n are connected to the adder circuit, and during the pen signal detection period T2, the loop coils LCx n ,LCx n+1 to the subtraction circuit, loop coil LCx n-1 are connected to the adder circuit, and during the pen signal detection period T3, the loop coils LCx nto the subtraction circuit, loop coil LCx n-1 ,LCx n+1 may be connected to an adder circuit, respectively.

[0158] In addition, the technique of the present invention may be applied to generate a reception signal Rx_EMR according to an arbitrary connection form of the loop coil LCx. For example, the difference E m,1 -E m,2 or a signal obtained by subtracting the sum signal of loop coils LCx3 and LCx4 from the sum signal of loop coils LCx1 and LCx2 (E m,1 +E m,2 )-(E m,3 +E m,4 In this way, it is possible to obtain the level of the pen signal according to an arbitrary connection form of the loop coils LCx. [Explanation of symbols]

[0159] 1 Position Detection System 3 Position detection device 30 Switch section 30a~30f,30k switch 30g,30m Drive circuit 30h Wiring section 30i Differential Amplifier 30j,30n op amp 31 Sensor Controller 32 Host Processor EL linear electrode F finger L1~L4 wiring LCx Loop Coil P Electromagnetic induction pen PA1, PA2 probing area PLC pseudo loop coil T1~T3 Pen signal detection period Tx,Tx_EMR AC current Tx_TP Touch detection signal Rx, Rx_EMR, Rx_TP Received signal

Claims

1. A sensor device for detecting a pointer, A group of linear electrodes extending parallel to each other; A detection coil group intersecting the linear electrode group; an integrated circuit connected to the linear electrode group and the detection coil group; The integrated circuit comprises: an alternating magnetic field is sequentially emitted from the linear electrode group, an alternating magnetic field generated by the indicator in response to the alternating magnetic field is detected by the detection coil group, and a linear electrode set consisting of a part of the linear electrode group is determined based on the detection result; Executing a process of emitting an alternating magnetic field from at least a part of the linear electrode set a plurality of times, and deriving a two-dimensional position of the indicator using a plurality of result values ​​detected by at least a part of the detection coil group as a result of each execution, updating the linear electrode set according to the derived two-dimensional position; the process of transmitting an alternating magnetic field 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 constituting the linear electrode set, and simultaneously supplying a first alternating current to half of the predetermined number of linear electrodes and a second alternating current different from the first alternating current to the remaining number of the predetermined number of linear electrodes, The first AC current and the second AC current are generated so as to satisfy a relationship in which their time derivatives are in opposite phase to each other. Sensor device.

2. the integrated circuit executes the process of emitting an alternating magnetic field from at least a part of the linear electrode set a plurality of times while changing a combination of the linear electrodes among the predetermined number of linear electrodes that supply the first alternating current and the linear electrodes among the predetermined number of linear electrodes that supply the second alternating current. The sensor device according to claim 1 .

3. A sensor device for detecting a pointer, A group of linear electrodes extending parallel to each other; A detection coil group intersecting the linear electrode group; an integrated circuit connected to the linear electrode group and the detection coil group; The integrated circuit comprises: an alternating magnetic field is sequentially emitted from the linear electrode group, an alternating magnetic field generated by the indicator in response to the alternating magnetic field is detected by the detection coil group, and a linear electrode set consisting of a part of the linear electrode group is determined based on the detection result; Executing a process of emitting an alternating magnetic field from at least a part of the linear electrode set a plurality of times, and deriving a two-dimensional position of the indicator using a plurality of result values ​​detected by at least a part of the detection coil group as a result of each execution, updating the linear electrode set according to the derived two-dimensional position; the process of generating an alternating magnetic field in at least a part of the linear electrode set is a process of selecting one of the plurality of linear electrodes constituting the linear electrode set, and simultaneously supplying a first alternating current to one or more linear electrodes adjacent to the selected linear electrode on one side thereof and a second alternating current different from the first alternating current to one or more linear electrodes adjacent to the selected linear electrode on the other side thereof, The first AC current and the second AC current are generated so as to satisfy a relationship in which their time derivatives are in opposite phase to each other. Sensor device.

4. A sensor device for detecting a pointer, A group of linear electrodes extending parallel to each other; A detection coil group intersecting the linear electrode group; an integrated circuit connected to the linear electrode group and the detection coil group; the integrated circuit is configured to supply a first AC current to one end in a longitudinal direction of one or more first linear electrodes in the group of linear electrodes, while supplying a second AC current to the one end in a longitudinal direction of one or more second linear electrodes different from the one or more first linear electrodes in the group of linear electrodes; The first AC current and the second AC current are generated so as to satisfy a relationship in which their time derivatives are in opposite phase to each other. Sensor device.

5. The relationship is: As the increase in the first AC current increases, the decrease in the second AC current increases, As the decrease in the first AC current increases, the increase in the second AC current increases. Relationship The sensor device according to claim 4.

6. the relationship being such that, as an increase in an electric potential of each of the one or more first linear electrodes with respect to one end in a longitudinal direction thereof increases, an increase in an electric potential of each of the one or more second linear electrodes with respect to the other end in a longitudinal direction thereof increases. The sensor device according to claim 4.

7. the one or more first linear electrodes are a predetermined number of linear electrodes adjacent to one side of one linear electrode selected from the linear electrode group, the one or more second linear electrodes are the predetermined number of linear electrodes adjacent to the other side of the one linear electrode, The sensor device according to claim 4.

8. a potential at the other end in the longitudinal direction of each of the one or more first linear electrodes and a potential at the other end in the longitudinal direction of each of the one or more second linear electrodes are a midpoint potential between a potential generated at the one end of the one or more first linear electrodes by the first current and a potential generated at the one end of the one or more second linear electrodes by the second current. The sensor device according to claim 4.

9. when the potential of the one or more first linear electrodes is greater than the midpoint, the potential of the one or more second linear electrodes is less than the midpoint; The sensor device according to claim 8.

10. An integrated circuit is connected to a group of linear electrodes extending parallel to each other and a group of detection coils intersecting the group of linear electrodes, and detects a pointer, an alternating magnetic field is sequentially emitted from the linear electrode group, an alternating magnetic field generated by the indicator in response to the alternating magnetic field is detected by the detection coil group, and a linear electrode set consisting of a part of the linear electrode group is determined based on the detection result; Executing a process of emitting an alternating magnetic field from at least a part of the linear electrode set a plurality of times, and deriving a two-dimensional position of the indicator using a plurality of result values ​​detected by at least a part of the detection coil group as a result of each execution, updating the linear electrode set according to the derived two-dimensional position; the process of transmitting an alternating magnetic field 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 constituting the linear electrode set, and simultaneously supplying a first alternating current to half of the predetermined number of linear electrodes and a second alternating current different from the first alternating current to the remaining number of the predetermined number of linear electrodes, The first AC current and the second AC current are generated so as to satisfy a relationship in which their time derivatives are in opposite phase to each other. Integrated circuits.

11. An integrated circuit for detecting a pointer, connected to a group of linear electrodes extending parallel to each other and a group of detection coils intersecting the group of linear electrodes, comprising: an alternating magnetic field is sequentially emitted from the linear electrode group, an alternating magnetic field generated by the indicator in response to the alternating magnetic field is detected by the detection coil group, and a linear electrode set consisting of a part of the linear electrode group is determined based on the detection result; Executing a process of emitting an alternating magnetic field from at least a part of the linear electrode set a plurality of times, and deriving a two-dimensional position of the indicator using a plurality of result values ​​detected by at least a part of the detection coil group as a result of each execution, updating the linear electrode set according to the derived two-dimensional position; the process of generating an alternating magnetic field in at least a part of the linear electrode set is a process of selecting one of the plurality of linear electrodes constituting the linear electrode set, and simultaneously supplying a first alternating current to one or more linear electrodes adjacent to the selected linear electrode on one side thereof and a second alternating current different from the first alternating current to one or more linear electrodes adjacent to the selected linear electrode on the other side thereof, The first AC current and the second AC current are generated so as to satisfy a relationship in which their time derivatives are in opposite phase to each other. Integrated circuits.

12. An integrated circuit is connected to a group of linear electrodes extending parallel to each other and a group of detection coils intersecting the group of linear electrodes, and detects a pointer, supplying a first AC current to one longitudinal end of one or more first linear electrodes in the linear electrode group, while supplying a second AC current to the one longitudinal end of one or more second linear electrodes different from the one or more first linear electrodes in the linear electrode group; The first AC current and the second AC current are generated so as to satisfy a relationship in which their time derivatives are in opposite phase to each other. Integrated circuits.

13. A method for detecting a pointer using a group of linear electrodes extending parallel to each other and a group of detection coils intersecting the group of linear electrodes, comprising: a step of sequentially transmitting an alternating magnetic field from the linear electrode group, detecting the alternating magnetic field generated by the indicator in response to the alternating magnetic field using the detection coil group, and determining a linear electrode set consisting of a portion of the linear electrode group based on the detection result; a step of executing a process of emitting an alternating magnetic field from at least a part of the linear electrode set a plurality of times, and deriving a two-dimensional position of the indicator using a plurality of result values ​​detected by at least a part of the detection coil group as a result of each execution; updating the linear electrode set in response to the derived two-dimensional position; the process of transmitting an alternating magnetic field 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 constituting the linear electrode set, and simultaneously supplying a first alternating current to half of the predetermined number of linear electrodes and a second alternating current different from the first alternating current to the remaining number of the predetermined number of linear electrodes, The first AC current and the second AC current are generated so as to satisfy a relationship in which their time derivatives are in opposite phase to each other. method.

14. A method for detecting a pointer using a group of linear electrodes extending parallel to each other and a group of detection coils intersecting the group of linear electrodes, comprising: a step of sequentially transmitting an alternating magnetic field from the linear electrode group, detecting the alternating magnetic field generated by the indicator in response to the alternating magnetic field using the detection coil group, and determining a linear electrode set consisting of a portion of the linear electrode group based on the detection result; a step of executing a process of emitting an alternating magnetic field from at least a part of the linear electrode set a plurality of times, and deriving a two-dimensional position of the indicator using a plurality of result values ​​detected by at least a part of the detection coil group as a result of each execution; updating the linear electrode set in response to the derived two-dimensional position; the process of generating an alternating magnetic field in at least a part of the linear electrode set is a process of selecting one of the plurality of linear electrodes constituting the linear electrode set, and simultaneously supplying a first alternating current to one or more linear electrodes adjacent to the selected linear electrode on one side thereof and a second alternating current different from the first alternating current to one or more linear electrodes adjacent to the selected linear electrode on the other side thereof, The first AC current and the second AC current are generated so as to satisfy a relationship in which their time derivatives are in opposite phase to each other. method.

15. A method for detecting a pointer using a group of linear electrodes extending parallel to each other and a group of detection coils intersecting the group of linear electrodes, comprising: generating a first AC current and a second AC current that satisfy a relationship in which their respective time derivatives are in opposite phase to each other; supplying a first AC current to one longitudinal end of one or more first linear electrodes in the linear electrode group, while supplying a second AC current to the one longitudinal end of one or more second linear electrodes different from the one or more first linear electrodes in the linear electrode group; The method includes:

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