Integrated Circuit and Sensor Controller

Abstract

An integrated circuit capable of switching the connection method between the receiving coil of an EMR sensor and a sensor controller is provided. The integrated circuit according to the present invention includes a switch circuit 30 connected to a plurality of loop coils LCx that are receiving coils of an EMR sensor, the plurality of loop coils LCx having ends T along a first side of a touch surface. 12 ,T 21 A differential amplifier 401 having a non-inverting input terminal and an inverting input terminal, 12 The connection destination is the inverting input terminal of the differential amplifier 401 and the end T 21 , the ground terminal, and the non-inverting input terminal of the differential amplifier 401.

Description

[Technical field]

[0001] The present invention relates to integrated circuits and sensor controllers, and more particularly to integrated circuits and sensor controllers for use with EMR sensors. [Background technology]

[0002] The electromagnetic induction method (EMR method) is known as one of methods for detecting the position of an electromagnetic induction pen on a panel surface of a tablet terminal or the like. A position detection device using the EMR method has a pen detection sensor (hereinafter referred to as "EMR sensor") arranged on the panel surface, and a sensor controller connected to the EMR sensor. The EMR sensor includes a transmitting coil consisting of multiple Tx coils arranged in a line in the y direction, and a receiving coil consisting of multiple Rx coils arranged in a line in the x direction. The sensor controller sequentially transmits alternating magnetic fields from the multiple Tx coils, and receives a reflected signal (hereinafter referred to as "pen signal") transmitted by the electromagnetic induction pen at each Rx coil, thereby detecting the position of the electromagnetic induction pen (hereinafter referred to as "pen position") and receiving data transmitted by the electromagnetic induction pen (hereinafter referred to as "pen data"). Patent documents 1 to 3 disclose examples of EMR sensors.

[0003] Patent Document 2 discloses an example of an EMR sensor that uses a loop coil as an Rx coil. Both ends of the Rx coil in Patent Document 2 are connected to two input terminals of a differential amplifier that outputs a pen signal. Patent Document 3 discloses an example of an EMR sensor that uses a linear electrode (hereinafter referred to as a "linear electrode") instead of an Rx coil. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6698386 [Patent Document 2] JP 2018-185559 A [Patent Document 3] JP 2022-117491 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, there are several methods for connecting each Rx coil that constitutes the receiving coil of an EMR sensor to a sensor controller. Specifically, there is a differential method in which both ends of the Rx coil are connected to the sensor controller, a single-ended method in which one end of the Rx coil is connected to the sensor controller and the other end is grounded, and a bundled input method in which multiple Rx coils are connected in series to the sensor controller. Each method has its own advantages, but conventional position detection devices are limited to one of them. Therefore, there was a demand for the ability to switch the connection method between each Rx coil and the sensor controller.

[0006] Therefore, one object of the present invention is to provide an integrated circuit capable of switching the connection method between the receiving coil of an EMR sensor and a sensor controller.

[0007] The inventor of the present application has also considered using a coil (hereinafter referred to as a "comb coil") configured by connecting a number of wires (hereinafter referred to as "comb teeth") extending in the y direction to one wire (hereinafter referred to as "base") extending in the x direction as the receiving coil of the EMR sensor, instead of the above-mentioned multiple Rx coils. One end of each comb tooth is connected to the base, and the other end is connected to the sensor controller. According to the research of the inventor of the present application, the sensor controller receives a pen signal by regarding the other ends of two adjacent comb tooth parts as both ends of the Rx coil, and thus can receive the pen signal as if the Rx coil were formed by the two comb tooth parts and the part of the base that connects them, even though each of the two comb tooth parts is actually connected to the other comb tooth part via the base. Therefore, it is possible to detect the pen position by using a comb coil as well as by using multiple Rx coils.

[0008] However, the comb coil has a problem in that the accuracy of detecting the pen position is low because the configuration of the comb coil is equivalent to virtual loop coils made up of two adjacent comb teeth arranged at an interval in the x direction.

[0009] Therefore, another object of the present invention is to provide an integrated circuit capable of improving the detection accuracy of the pen position when a comb coil is used as the receiving coil of an EMR sensor.

[0010] In addition, since an alternating magnetic field appears in the Rx coil while the Tx coil is emitting the alternating magnetic field, the sensor controller receives the pen signal in the Rx coil after stopping the emission of the alternating magnetic field from the Tx coil. However, due to the effect of the time constant of the Rx coil, the effect remains in the Rx coil even after the emission of the alternating magnetic field from the Tx coil has stopped, deteriorating the SNR (Signal to Noise Ratio) of the pen signal.

[0011] Therefore, it is yet another object of the present invention to provide an integrated circuit and a sensor controller capable of improving the SNR of a pen signal.

[0012] The inventor of the present application has also considered using a coil (hereinafter referred to as a "comb coil") configured by connecting a number of wires (hereinafter referred to as "comb teeth") extending in the y direction to one wire (hereinafter referred to as "base") extending in the x direction as the receiving coil of the EMR sensor, instead of the above-mentioned multiple Rx coils. One end of each comb tooth is connected to the base, and the other end is connected to the sensor controller. According to the research of the inventor of the present application, the sensor controller receives a pen signal by regarding the other ends of two adjacent comb tooth parts as both ends of the Rx coil, and thus can receive the pen signal as if the Rx coil were formed by the two comb tooth parts and the part of the base that connects them, even though each of the two comb tooth parts is actually connected to the other comb tooth part via the base. Therefore, it is possible to detect the pen position by using a comb coil as well as by using multiple Rx coils.

[0013] However, the comb coil has a problem in that the accuracy of detecting the pen position is low because the configuration of the comb coil is equivalent to virtual loop coils made up of two adjacent comb teeth arranged at an interval in the x direction.

[0014] Therefore, a further object of the present invention is to provide an integrated circuit and a sensor controller capable of improving the detection accuracy of the pen position when a comb coil is used as the receiving coil of an EMR sensor.

[0015] Furthermore, when using a linear electrode instead of an Rx coil as in Patent Document 2, the sign of the pen signal is opposite between the linear electrode on one side of the pen position in the x-direction and the linear electrode on the other side of the x-direction, and a sign transition occurs near the pen position, resulting in a problem that the received strength of the pen signal becomes weak near the pen position.

[0016] Therefore, a further object of the present invention is to provide an integrated circuit and a sensor controller capable of increasing the reception strength of a pen signal when a linear electrode is used instead of an Rx coil.

[0017] In addition, in conventional position detection devices, when the electromagnetic induction pen is tilted relative to the panel surface, the peak position of the pen signal received by the Rx coil may shift from the actual position of the pen tip depending on the azimuth angle of the electromagnetic induction pen. This causes a deterioration in the detection accuracy of the pen position, so an improvement was needed.

[0018] Therefore, a further object of the present invention is to provide a sensor controller that can detect the position of an electromagnetic induction pen with high accuracy even if the pen is tilted relative to the panel surface.

[0019] In addition, in recent years, displays that can be folded (foldable displays) have appeared, and it is required that the position of an electromagnetic induction pen can be detected in these foldable displays as well. However, in foldable displays, conductive hinge parts are used to realize folding, and since the hinge parts disturb the magnetic field, there is a problem that the reception strength of the pen signal is weakened in the vicinity of the hinge parts, i.e., in the vicinity of the folding line.

[0020] Therefore, yet another object of the present invention is to provide an integrated circuit and a sensor controller that can increase the reception strength of a pen signal in the vicinity of a folding line of a foldable display. [Means for solving the problem]

[0021] An integrated circuit according to a first aspect of the present invention is an integrated circuit connected to a receiving coil of an EMR sensor, the receiving coil having a plurality of ends along a first side of a touch surface, the plurality of ends including a first end and a second end, the integrated circuit including: a differential amplifier having a first input terminal and a second input terminal; and a group of switches that switch the connection destination of the first end between the second input terminal and any one of the second end, a ground terminal, and the first input terminal.

[0022] An integrated circuit according to a second aspect of the present invention is the integrated circuit according to the first aspect, wherein the receiving coil is a comb coil having the multiple ends, and the group of switches switches in a time-division manner between a first state in which the first end is connected to the second input terminal, and a second state in which the first end is connected to the first input terminal.

[0023] An integrated circuit according to a third aspect of the present invention is an integrated circuit connected to an EMR sensor, wherein a receiving coil of the EMR sensor is composed of a plurality of first loop coils, and the integrated circuit includes a plurality of differential amplifiers each having a first input terminal and a second input terminal, a first wiring connecting one end of each of the plurality of first loop coils to the first input terminal of the corresponding differential amplifier, a second wiring connecting the other end of each of the plurality of first loop coils to the second input terminal of the corresponding differential amplifier, and a first switch element provided between a power supply wiring to which a predetermined power supply potential is supplied and the first wiring.

[0024] A sensor controller according to a third aspect of the present invention is a sensor controller connected to the EMR sensor via the integrated circuit according to the first aspect of the present invention, wherein the plurality of first loop coils each extend in a first direction and are arranged side by side in a second direction intersecting the first direction, a transmitting coil of the EMR sensor each extend in the second direction and is constituted by a plurality of second loop coils arranged side by side in the first direction, and the integrated circuit has a first state in which one end and the other end of a 2n-1th (n is a natural number) first loop coil from one end side in the second direction among the plurality of first loop coils are connected to the first input terminal and the second input terminal of the corresponding differential amplifier, while one end and the other end of a 2nth first loop coil are disconnected from the first input terminal and the second input terminal of the corresponding differential amplifier, and a second state in which a second end and the other end of a 2nth first loop coil from one end side in the second direction among the plurality of first loop coils are connected to the first input terminal and the second input terminal of the corresponding differential amplifier, a switch circuit configured to be able to switch between a first state in which one end and the other end of a first loop coil are connected to the first input terminal and the second input terminal of the corresponding differential amplifier, and a second state in which one end and the other end of the (2n-1)th first loop coil are disconnected from the first input terminal and the second input terminal of the corresponding differential amplifier, and an alternating magnetic field is transmitted from the EMR sensor by sequentially passing a current through each of the plurality of second loop coils, and the switch circuit is set to the first state when the current is passed through the second loop coil that is 2m-1th (m is a natural number) from one end side in the first direction among the plurality of second loop coils, and the switch circuit is set to the second state when the current is passed through the loop coil that is 2mth from one end side in the first direction among the plurality of loop coils, thereby receiving a pen signal output from each of the plurality of differential amplifiers.

[0025] An integrated circuit according to a fourth aspect of the present invention is an integrated circuit connected to an EMR sensor, wherein a receiving coil of the EMR sensor is a comb coil having a configuration in which a plurality of comb tooth portions each extending in a first direction are connected at one end to a base portion extending in a second direction intersecting the first direction, and the integrated circuit includes a plurality of differential amplifiers each having a first input terminal and a second input terminal, and a switch circuit configured to be able to switch between a first state in which the other end of a 2n-1th (n is a natural number) comb tooth portion from one end side in the second direction among the plurality of comb tooth portions and the other end of a 2n-th comb tooth portion from one end side in the second direction among the plurality of comb tooth portions are connected to the first input terminal and the second input terminal of the same differential amplifier, and a second state in which the other end of a 2nth comb tooth portion from one end side in the second direction among the plurality of comb tooth portions and the other end of a 2n+1th comb tooth portion from one end side in the second direction among the plurality of comb tooth portions are connected to the first input terminal and the second input terminal of the same differential amplifier, respectively.

[0026] A sensor controller according to a fourth aspect of the present invention is a sensor controller connected to the EMR sensor via the integrated circuit according to the second aspect of the present invention, wherein the transmitting coil of the EMR sensor is composed of a plurality of loop coils each extending in the second direction and arranged in a line in the first direction, and an alternating magnetic field is transmitted from the EMR sensor by sequentially passing a current through each of the plurality of loop coils, and the switch circuit is set to the first state when the current is passed through the 2m-1th (m is a natural number) loop coil from one end side in the first direction among the plurality of loop coils, and the switch circuit is set to the second state when the current is passed through the 2mth loop coil from one end side in the first direction among the plurality of loop coils, thereby receiving a pen signal output from each of the plurality of differential amplifiers.

[0027] An integrated circuit according to a fifth aspect of the present invention is an integrated circuit connected to an EMR sensor, wherein a receiving coil of the EMR sensor is composed of a plurality of linear electrodes each extending in a first direction and arranged in a second direction intersecting the first direction, and includes a plurality of differential amplifiers each having a first input terminal and a second input terminal, and wiring connecting an end of a 2n-kth (k is an odd natural number, n is a natural number greater than k / 2) linear electrode among the plurality of linear electrodes from one end side in the second direction and an end of a 2nth linear electrode to the first input terminal and the second input terminal of the same differential amplifier, respectively.

[0028] A sensor controller according to a fifth aspect of the present invention is a sensor controller connected to the EMR sensor via the integrated circuit according to the third aspect of the present invention, wherein the transmitting coil of the EMR sensor is composed of a plurality of loop coils each extending in the second direction and arranged in a line in the first direction, and an alternating magnetic field is transmitted from the EMR sensor by sequentially passing a current through each of the plurality of loop coils, and the switch circuit is set to the first state when the current is passed through the 2m-1th loop coil (m is a natural number) from one end side in the first direction among the plurality of loop coils, and the switch circuit is set to the second state when the current is passed through the 2mth loop coil from one end side in the first direction among the plurality of loop coils, thereby receiving a pen signal output from each of the plurality of differential amplifiers.

[0029] A sensor controller according to a sixth aspect of the present invention is a sensor controller connected to an EMR sensor having a plurality of loop coils, which adds up a pen signal received at a first loop coil among the plurality of loop coils and a pen signal received at each of one or more other loop coils among the plurality of loop coils that are located in the vicinity of the first loop coil, with different weightings, and derives the position of the electromagnetic induction pen using an added pen signal obtained by the addition.

[0030] According to a seventh aspect of the present invention, there is provided an integrated circuit connected to an EMR sensor, the receiving coil of the EMR sensor being a comb coil having a configuration in which a plurality of comb-tooth portions each extending in a first direction are connected at one end to a base portion extending in a second direction intersecting the first direction, the receiving coil including a receiving circuit for receiving a pen signal transmitted by an electromagnetic induction pen, and a selection circuit for selecting two of the plurality of comb-tooth portions and connecting the selected two of the comb-tooth portions to the receiving circuit, the plurality of comb-tooth portions being connected to a base portion extending in the second direction intersecting the first direction. the selection circuit performs the selection so that a first state in which first and third comb tooth portions are selected from the plurality of comb tooth portions and a second state in which second and fourth comb tooth portions are selected from the plurality of comb tooth portions appear in sequence, a distance between the first comb tooth portion and the third comb tooth portion and a distance between the second comb tooth portion and the fourth comb tooth portion are both a first distance, and a distance between the first comb tooth portion and the second comb tooth portion is a second distance shorter than the first distance.

[0031] A sensor controller according to a seventh aspect of the present invention is an integrated circuit according to the seventh aspect of the present invention, further comprising: the plurality of comb tooth portions having a fifth comb tooth portion on the other side of the fourth comb tooth portion in the second direction; the selection circuit is a sensor controller connected to the EMR sensor via an integrated circuit that performs the selection so that the first state, the second state, and a third state that selects the third comb tooth portion and the fifth comb tooth portion appear in sequence; and the sensor controller controls the selection circuit so that the first state, the second state, and the third state appear in sequence. Effect of the Invention

[0032] According to the first aspect of the present invention, it is possible to switch the connection method between the receiving coil of the EMR sensor and the sensor controller by controlling the switch group.

[0033] According to the second aspect of the present invention, reception of a pen signal in a first state and reception of a pen signal in a second state can be executed in a time-division manner, and therefore the spacing between the virtual loop coils can be effectively made zero, thereby improving the detection accuracy of the pen position when a comb coil is used as the receiving coil of the EMR sensor.

[0034] According to the third aspect of the present invention, each first loop coil can be precharged by turning on the first switch element, thereby eliminating the influence of the alternating magnetic field emitted from the transmitting coil from the receiving coil, and improving the SNR of the pen signal.

[0035] According to the fourth aspect of the present invention, reception of a pen signal in a first state and reception of a pen signal in a second state can be executed in a time-division manner, and therefore the spacing between the virtual loop coils can be effectively made zero, thereby improving the detection accuracy of the pen position when a comb coil is used as the receiving coil of an EMR sensor.

[0036] According to the fifth aspect of the present invention, pen signals having opposite signs are reinforced by a differential amplifier, making it possible to increase the received strength of the pen signal in the vicinity of the pen position when a linear electrode is used as an Rx coil.

[0037] According to a sixth aspect of the present invention, the position of the electromagnetic induction pen is derived using an added pen signal obtained by adding pen signals received by multiple loop coils with different weighting, so that even if the electromagnetic induction pen is tilted relative to the panel surface, its position can be detected with high accuracy.

[0038] According to the seventh aspect of the present invention, the virtual loop coil is shifted by a distance shorter than the distance between the two comb tooth portions that constitute the virtual loop coil, thereby making it possible to increase the reception strength of the pen signal in the vicinity of the folding line of the foldable display. [Brief description of the drawings]

[0039] [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 circuit 30 shown in FIG. 1 and a state of the switch circuit 30 in a differential system. [Diagram 3] 2 is a diagram showing an internal configuration of a switch circuit 30 shown in FIG. 1 and a state of the switch circuit 30 in a single-ended system. [Figure 4] 2 is a diagram showing an internal configuration of a switch circuit 30 shown in FIG. 1 and a first state of the switch circuit 30 in a bundled input method. [Diagram 5] 2 is a diagram showing an internal configuration of the switch circuit 30 shown in FIG. 1 and a second state of the switch circuit 30 in the bundled input method. [Figure 6] FIG. 1 is a diagram showing a configuration of a position detection system 1 according to a second embodiment of the present invention. [Figure 7] 7 is a diagram illustrating an internal configuration and a first state of the switch circuit 30 illustrated in FIG. 6. [Figure 8] 7 is a diagram illustrating an internal configuration and a second state of the switch circuit 30 illustrated in FIG. 6. [Figure 9] FIG. 11 is a diagram showing a first state of a switch circuit 30 according to a first modified example of the second embodiment of the present invention. [Figure 10] FIG. 13 is a diagram illustrating a second state of the switch circuit 30 according to the first modified example of the second embodiment of the present invention. [Figure 11] FIG. 11 is a diagram showing a first state of a switch circuit 30 according to a second modified example of the second embodiment of the present invention. [Figure 12] FIG. 13 is a diagram illustrating a second state of the switch circuit 30 according to the second modified example of the second embodiment of the present invention. [Figure 13] FIG. 11 is a diagram showing an internal configuration of a switch circuit 30 according to a third embodiment of the present invention. [Figure 14] 14 is a diagram showing waveforms of signals relating to the control of switch elements S1, S2, T1, and T2 shown in FIG. 13. [Figure 15] FIG. 13 is a diagram illustrating a method of driving the EMR sensor according to a modified example of the third embodiment of the present invention. [Figure 16] FIG. 11 is a diagram showing a configuration of a position detection system 1 according to a fourth embodiment of the present invention. [Figure 17] 17 is a diagram illustrating an internal configuration and a first state of the switch circuit 30 illustrated in FIG. 16. [Figure 18] 17 is a diagram illustrating an internal configuration and a second state of the switch circuit 30 illustrated in FIG. 16. FIG. [Figure 19] FIG. 13 is a diagram illustrating a method of driving the EMR sensor according to a modified example of the fourth embodiment of the present invention. [Figure 20] FIG. 13 is a diagram showing a configuration of a position detection system 1 according to a fifth embodiment of the present invention. [Figure 21] 21 is a diagram illustrating an internal configuration and a first state of the switch circuit 30 illustrated in FIG. 20. FIG. [Figure 22] 21 is a diagram illustrating an internal configuration and a second state of the switch circuit 30 illustrated in FIG. 20. FIG. [Figure 23] FIG. 13 is a diagram showing a simulation result of the reception strength of a pen signal. [Figure 24] 13 is a diagram showing an internal configuration and a first state of a switch circuit 30 included in a position detection system 1 according to a first modified example of the fifth embodiment of the present invention. FIG. [Diagram 25] 13 is a diagram showing an internal configuration and a second state of a switch circuit 30 included in a position detection system 1 according to a first modified example of the fifth embodiment of the present invention. FIG. [Figure 26] FIG. 23 is a diagram illustrating a method of driving the EMR sensor according to a second modified example of the fifth embodiment of the present invention. [Figure 27] 13A to 13C are diagrams illustrating problems that arise when a pen signal is received using a position detection system 1 according to a third embodiment of the present invention. [Figure 28] 28 is a diagram for explaining the azimuth angle θ and the tilt angle φ used in FIG. 27. FIG. [Figure 29]FIG. 13A is a diagram for explaining the processing performed by a sensor controller 31 according to a sixth embodiment of the present invention, and FIG. 13B is a diagram showing a virtual loop coil VLCx obtained by the addition shown in FIG. [Diagram 30] 13 is a diagram showing the reception level of the addition pen signal PSSUM when the pen tip of the electromagnetic induction pen 2 is at the position of x coordinate=0 mm. FIG. [Diagram 31] 13A is a plan view of an EMR sensor 33 included in a position detection device 3 according to a seventh embodiment of the present invention, and FIG. 13B is a cross-sectional view of the EMR sensor 33 corresponding to the line AA shown in FIG. [Diagram 32] 13(a) is a diagram illustrating the distribution of reception levels of the pen signal PS received when the tip of the electromagnetic induction pen 2 is at each position in the x direction, assuming that the ODD / EVEN method is adopted in the position detection device 3 according to the seventh embodiment of the present invention, and FIG. 13(b) is a diagram illustrating the distribution of reception levels of the pen signal PS received when the tip of the electromagnetic induction pen 2 is at each position in the x direction, assuming that the ODD / EVEN method is adopted in the position detection device 3 according to the seventh embodiment of the present invention (i.e., a position detection device 3 adopting the A / B / C method). [Diagram 33] FIG. 13 is a diagram showing an internal configuration and a first state of a switch circuit 30 according to a seventh embodiment of the present invention. [Diagram 34] FIG. 13 is a diagram showing an internal configuration and a second state of a switch circuit 30 according to a seventh embodiment of the present invention. [Diagram 35] FIG. 13 is a diagram showing an internal configuration and a third state of a switch circuit 30 according to a seventh embodiment of the present invention. [Diagram 36] This figure plots the maximum reception level of the pen signal PS observed when the ODD / EVEN method is adopted and the maximum reception level of the pen signal PS observed when the A / B / C method is adopted, for each distance (pen height) from the touch surface 3a to the tip of the electromagnetic induction pen 2. [Figure 37] FIG. 23 is a diagram illustrating a process performed by the sensor controller 31 according to a modified example of the seventh embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0041] 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 2 and a position detection device 3. Of these, the electromagnetic induction pen 2 is a pen compatible with position detection by the EMR method, and is configured to have an internal resonance circuit including a coil and a capacitor.

[0042] The position detection device 3 is a device configured to be able to detect the position of an electromagnetic induction pen 2 within a touch surface 3a (panel surface) by the EMR method. Within the touch surface 3a, a plurality of loop coils LCx (Rx coils) which are receiving coils of the EMR sensor, and a plurality of loop coils LCy (Tx coils) which are transmitting coils of the EMR sensor are arranged. In addition to these, the position detection device 3 is configured to include a switch circuit 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 doubles as the touch surface 3a, but the position detection device 3 may also be configured by a digitizer that does not have a display surface.

[0043] The illustrated x and y directions are directions within the touch surface 3a and are mutually perpendicular. The multiple loop coils LCx are formed to extend in the y direction and are arranged side by side in the x direction. On the other hand, the multiple loop coils LCy are formed to extend in the x direction and are arranged side by side in the y direction. Note that both loop coils LCx and LCy may be arranged to overlap with other adjacent loop coils LCx and LCy, in which case they are formed three-dimensionally using via conductors or the like. Both ends of each loop coil LCx and each loop coil LCy are connected to the switch circuit 30. The end of each loop coil LCx is arranged along a side E1, which is one side of the rectangular touch surface 3a.

[0044] The switch circuit 30 is a group of switches (a switch group) 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 sensor controller 31. The switch circuit 30 may be configured as an integrated circuit by itself, or may be provided in the same integrated circuit as the sensor controller 31. The switching state of the switch circuit 30 is controlled by the sensor controller 31.

[0045] The sensor controller 31 is an integrated circuit having a function of detecting the position (pen position) of the electromagnetic induction pen 2 on the touch surface 3a by the EMR method. The sensor controller 31 controls the connection state of the loop coils LCx and LCy by controlling the switch circuit 30, thereby supplying AC current to each of the multiple loop coils LCy in sequence, and performs processing to receive a pen signal generated in each loop coil LCx each time. The sensor controller 31 is configured to derive the pen position based on the pen signal thus received, and to receive pen data transmitted by the electromagnetic induction pen 2.

[0046] More specifically, when the sensor controller 31 starts supplying an AC current to any of the loop coils LCy, that loop coil LCy starts emitting an AC magnetic field. When the coil of the electromagnetic induction pen 2 enters this AC magnetic field, an electromotive force is generated at both ends, charging the capacitor of the electromagnetic induction pen 2. When the sensor controller 31 subsequently stops supplying AC current to the loop coil LCy, the power stored in the capacitor of the electromagnetic induction pen 2 causes the coil of the electromagnetic induction pen 2 to emit an AC magnetic field (pen signal).

[0047] Here, the electromagnetic induction pen 2 is configured to be able to transmit pen data, such as a pen pressure value indicating the pressure applied to the pen tip and on / off information indicating the on / off state of a switch provided on the surface, using a pen signal. That is, the capacitor constituting the resonant circuit of the electromagnetic induction pen 2 is configured so that its capacitance changes according to the value of the pen data. When the capacitance of the capacitor changes, the resonant frequency of the resonant circuit changes according to the amount of change, and therefore the frequency of the alternating magnetic field emitted from the coil changes according to the value of the pen data. Using the properties of such a resonant circuit, the electromagnetic induction pen 2 is configured to frequency-modulate the alternating magnetic field emitted from the coil using the pen data.

[0048] The pen signal sent from the coil of the electromagnetic induction pen 2 is received by each loop coil LCx. The sensor controller 31 receives the pen signal at each loop coil LCx while changing the loop coil LCy that supplies AC current under the control of the switch circuit 30, and acquires the strength of the pen signal for each combination of the loop coil LCy and the loop coil LCx. Then, based on each acquired strength, the intensity distribution of the pen signal on the touch surface 3a is derived, and the apex of the distribution is detected as the pen position. The sensor controller 31 also acquires pen data by detecting a change in the frequency of the pen signal received with the strongest strength. The sensor controller 31 is configured to supply the position detected as described above and the acquired data to the host processor 32 each time.

[0049] Here, the detection of the pen position by the sensor controller 31 is executed in one of two modes: global scan and local scan. Global scan is a process executed when the pen position has not yet been detected, and the sensor controller 31 executes the above-mentioned series of processes using all the loop coils LCx and LCy. This enables the sensor controller 31 to detect the electromagnetic induction pen 2 over the entire touch surface 3a.

[0050] On the other hand, local scan is a process executed when a pen position has already been detected. In this case, the sensor controller 31 executes the above-mentioned series of processes using only the loop coils LCx and LCy located near the previously detected pen position. This reduces the time required for one position detection, so that the sensor controller 31 can detect the pen position more frequently than in global scan.

[0051] The sensor controller 31 is configured to select any one of the above-mentioned differential, single-end, and bundled input methods for receiving the pen signal in each loop coil LCx. This selection may be performed during the manufacturing stage of the sensor controller 31 or the position detection device 3, or may be performed when the user uses the device. In one example, the sensor controller 31 may select the bundled input method when the pen pressure value included in the latest received pen data indicates that the electromagnetic induction pen 2 is hovering (a state in which the pen tip is not in contact with the touch surface 3a), and may select the differential or single-end method when the pen is touching (a state in which the pen tip is in contact with the touch surface 3a). The sensor controller 31 controls the switch circuit 30 according to the result of the selection, and as a result, reception of the pen signal in the selected method is realized. The specific contents of the control of the switch circuit 30 by the sensor controller 31 will be described in detail later with reference to Figs. 2 to 5.

[0052] The host processor 32 is a central processing unit of the position detection device 3 that executes the operating system and various applications of the position detection device 3 by executing a program read from a memory (not shown). The processes executed by the host processor 32 according to the program include various processes performed using the pen position and pen data supplied from the sensor controller 31. These various processes include, for example, the movement of a cursor displayed on the display surface, and the generation of stroke data indicating the trajectory of the electromagnetic induction pen 2 on the touch surface. Among these, with regard to the stroke data, the host processor 32 also performs a process of rendering and displaying the generated stroke data, a process of generating and recording digital ink including the generated stroke data, and a process of transmitting the generated digital ink to an external device in response to a user's instruction.

[0053] 2 to 5 are diagrams showing the internal configuration of the switch circuit 30. These diagrams show only the parts of the internal configuration of the switch circuit 30 that are related to reception of a pen signal by each loop coil LCx. Below, with reference to these diagrams, the internal configuration of the switch circuit 30 and the specific content of the control of the switch circuit 30 performed by the sensor controller 31 to realize each of the differential method, the single-ended method, and the bundled input method will be described in detail.

[0054] For the sake of simplicity, only two loop coils LCx1 and LCx2 are shown in Figs. 2 to 5, but the actual position detection device 3 naturally has more loop coils LCx. In the following, both ends of the loop coil LCx1 are referred to as ends T 11 ,T 12 The ends of the loop coil LCx2 are called ends T 21 ,T 22 It is called.

[0055] 2, the switch circuit 30 includes a plurality of differential amplifiers 40 and a switch group including a plurality of switches 50 to 55. The differential amplifier 40 is provided for each loop coil LCx. The switches 50, 51, and 52 are single-pole double-throw switches, and the switches 53 and 54 are single-pole triple-throw switches, each of which is provided for each loop coil LCx. The switch 55 is a single-pole double-throw switch, and is provided for each pair of adjacent loop coils LCx. In the following description, as necessary, the configuration corresponding to the loop coil LCx1 may be distinguished from the other configurations by adding a subscript "1" to the right of the reference numeral, the configuration corresponding to the loop coil LCx2 may be distinguished by adding a subscript "2" to the right of the reference numeral, and the configuration corresponding to both the loop coils LCx1 and LCx2 may be distinguished by adding a subscript "12" to the right of the reference numeral.

[0056] Each differential amplifier 40 is an amplifier circuit (differential amplifier) ​​that has a non-inverting input terminal, an inverting input terminal, and an output terminal, amplifies the potential difference between the non-inverting input terminal and the inverting input terminal, and outputs the amplified potential difference from the output terminal as an output voltage with respect to the ground potential. The output terminal of each differential amplifier 40 is supplied to the sensor controller 31 as a pen signal.

[0057] The common terminal of the switch 501 is the end T 11 , one selection terminal is connected to the ground terminal, and the other selection terminal is connected to the node n 11 The common terminal of the switch 511 is the terminal T 12 , one selection terminal is connected to the ground terminal, and the other selection terminal is connected to the node n 12 The common terminal of the switch 521 is a node n 12 One selection terminal is connected to node n 11 , and the other selection terminal is connected to a second selection terminal of a switch 531. The common terminal of the switch 531 is connected to the non-inverting input terminal of the differential amplifier 401, and the first selection terminal is connected to a node n 11 The common terminal of the switch 541 is connected to the inverting input terminal of the differential amplifier 401, and the first selection terminal is connected to the node n12 The second selection terminal is connected to a node n 21 and the third selection terminal is connected to the ground terminal.

[0058] The common terminal of switch 502 is terminal T 21 , one selection terminal is connected to the ground terminal, and the other selection terminal is connected to the node n 21 The common terminal of the switch 512 is the terminal T 22 , one selection terminal is connected to the ground terminal, and the other selection terminal is connected to the node n 22 The common terminal of the switch 522 is connected to the node n 22 One selection terminal is connected to node n 21 , and the other selection terminal is connected to a second selection terminal of a switch 532. The common terminal of the switch 532 is connected to the non-inverting input terminal of the differential amplifier 402, and the first selection terminal is connected to a node n 21 The common terminal of the switch 542 is connected to the inverting input terminal of the differential amplifier 402, and the first selection terminal is connected to the node n 22 and the third selection terminal is connected to the ground terminal. Although not shown, the second selection terminal of the switch 542 is connected to the other selection terminal of the switch 50 corresponding to the other loop coil LCx that is adjacent to the loop coil LCx2 on the opposite side to the loop coil LCx1.

[0059] The common terminal of the switch 55 is the end T 12 , and one selection terminal is connected to the end T 21 The other select terminal of switch 55 is not connected anywhere, so switch 55 may be a single-pole, single-throw switch.

[0060] With the above configuration, the switch circuit 30 is 12 (first end) is connected to the inverting input terminal (second input terminal) of the differential amplifier 401 and the end T 21The sensor controller 31 serves to switch between the input terminal (second end), the ground end, and the non-inverting input terminal (first input terminal) of the differential amplifier 401. By controlling this switching, the sensor controller 31 realizes reception of the pen signal by each of the differential method, the single-ended method, and the bundled input method. This will be described in detail below.

[0061] 2 shows the state of the switch circuit 30 after being controlled by the sensor controller 31 that has selected the differential method. In this case, the sensor controller 31 connects the other selection terminal of each of the switches 50 and 51 to a common terminal, and connects the first selection terminal of each of the switches 53 and 54 to the common terminal. The switches 52 and 55 are in a disconnected state (or in a state in which the other selection terminal of each is selected). As a result, as shown by the dashed lines in FIG. 2, both ends of the corresponding loop coil LCx are connected to each differential amplifier 40. For example, in the case of the differential amplifier 401, the non-inverting input terminal is connected to the end T of the loop coil LCx1. 11 The inverting input terminal is connected to the end T of the loop coil LCx1. 12 The differential method has the advantage that common mode noise can be removed from the pen signal received by each loop coil LCx, and the signal strength of the pen signal received by each loop coil LCx is greater than that of the single-ended method described below.

[0062] FIG. 3 shows the state of the switch circuit 30 after being controlled by the sensor controller 31 that has selected the single-ended method. In this case, the sensor controller 31 connects the other selection terminal of the switch 50 to the common terminal, connects the first selection terminal of the switch 53 to the common terminal, connects one selection terminal of the switch 51 to the common terminal, and connects the third selection terminal of the switch 54 to the common terminal. The switches 52 and 55 are in a disconnected state (or in a state in which the other selection terminal of each is selected) as in the case of FIG. 2. As a result, as shown by the dashed lines in FIG. 3, in each differential amplifier 40, only the non-inverting input terminal is connected to one end of the corresponding loop coil LCx, and the inverting input terminal is connected to the ground terminal. Also, the other end of each loop coil LCx is connected to the ground terminal. For example, in the differential amplifier 401, the non-inverting input terminal is connected to the end T of the loop coil LCx1. 11 The inverting input terminal is connected to the ground terminal, and the end T of the loop coil LCx1 is connected to the 12 is connected to the ground terminal. According to the single-ended method, the effect is that the sensor controller 31 can receive the pen signal even if the differential amplifier 40 is not connected to both ends of the loop coil LCx.

[0063] 4 and 5 show the state of the switch circuit 30 after being controlled by the sensor controller 31 that has selected the bundled input method. In this case, the sensor controller 31 controls the switch circuit 30 so that the first state shown in Fig. 4 and the second state shown in Fig. 5 are realized in a time-division manner for each loop coil LCy.

[0064] 4, the first state is a state in which two adjacent loop coils LCx are connected in series between the non-inverting input terminal and the inverting input terminal of each differential amplifier 40. To be more specific with reference to FIG. 4, in order to realize the first state, the sensor controller 31 connects the other selection terminal of the switches 501 and 512 to the common terminal, and switches 522 and 55 124, one selection terminal of the switch 531 is connected to the common terminal, the first selection terminal of the switch 531 is connected to the common terminal, the second selection terminal of the switch 541 is connected to the common terminal, and the switches 502, 511, 521, 532, and 542 are disconnected. As a result, as shown by the dashed lines in Fig. 4, the two loop coils LCx1 and LCx2 are connected in series between the non-inverting input terminal and the inverting input terminal of the differential amplifier 401. The same applies to the other loop coils LCx not shown.

[0065] 5, in the second state, the combination of two loop coils LCx connected in series to each differential amplifier 40 is shifted by one in the x direction compared to the first state. In addition to this shift, the contents of the control of the switch circuit 30 performed by the sensor controller 31 to realize the second state are the same as those in the first state.

[0066] According to the bundled input method, since two loop coils LCx are connected in series, the inductance is doubled, and the reception strength of the pen signal is increased accordingly. However, since the first state shown in FIG. 4 and the second state shown in FIG. 5 must be performed in a time-division manner, it takes twice as long to receive the pen signal as in the differential or single-end method. As described above, the sensor controller 31 selects the bundled input method when the pen pressure value included in the latest received pen data indicates that the electromagnetic induction pen 2 is in hover, and selects the differential or single-end method when the pen is in touch. In this way, during hovering, when the distance between the coil in the electromagnetic induction pen 2 and the touch surface 3a is large and the reception strength of the pen signal tends to be small, the bundled input method is used to increase the reception strength of the pen signal, and during pen touch, when a sufficiently large reception strength is obtained, the differential or single-end method is used to shorten the time required to receive the pen signal. In this way, adaptive switching of the connection method can be realized.

[0067] As described above, according to the position detection system 1 of this embodiment, it is possible to switch the connection method between the receiving coil of the EMR sensor and the sensor controller 31 among the differential method, the single-ended method, and the bundled input method by controlling the switches in the switch circuit 30 from the sensor controller 31. Therefore, the sensor controller 31 can detect the pen position and acquire pen data while making the most of the advantages of each method.

[0068] FIG. 6 is a diagram showing a configuration of a position detection system 1 according to a second embodiment of the present invention. The position detection system 1 according to this embodiment differs from the position detection system 1 according to the first embodiment in that a comb coil CCx consisting of a base portion PB and a plurality of comb teeth portions PT is used as a receiving coil of the EMR sensor, instead of a plurality of loop coils LCx. In addition, the internal configuration of the switch circuit 30 and the contents of the control of the switch circuit 30 by the sensor controller 31 are also different from those of the position detection system 1 according to the first embodiment. Since the position detection system 1 according to the first embodiment is otherwise similar to the position detection system 1 according to the first embodiment, the following description will focus on the differences from the position detection system 1 according to the first embodiment.

[0069] 6, the comb coil CCx is configured by connecting a base portion PB, which is a single wire extending in the x direction, to a plurality of comb tooth portions PT, which are wires extending in the y direction. One end of each comb tooth portion PT is connected to the base portion PB, and the other end is connected to the switch circuit 30. The other end of each comb tooth portion PT is disposed along a side E1, which is one side of the rectangular touch surface 3a.

[0070] 7 and 8 are diagrams showing the internal configuration of the switch circuit 30 according to this embodiment. These diagrams show only the part of the internal configuration of the switch circuit 30 that is related to reception of a pen signal by the comb coil CCx. Hereinafter, with reference to these diagrams, a method in which the sensor controller 31 receives a pen signal using the comb coil CCx will be described in detail.

[0071] 7 and 8 show only four comb tooth portions PT1 to PT4 for ease of explanation, but the actual comb coil CCx has many more comb tooth portions PT. In the following, the other ends of the comb tooth portions PT1 to PT4 (the ends opposite to the ends connected to the base portion PB) are referred to as ends T1 to T4.

[0072] 7, the switch circuit 30 according to the present embodiment includes a plurality of differential amplifiers 40 and a switch group including a plurality of switches 60-62. One differential amplifier 40 is provided for every two comb tooth portions PT. The switch 60 is a single-pole double-throw switch, and the switch 62 is a single-pole triple-throw switch, each of which is provided for each comb tooth portion PT. The switch 61 is a single-pole double-throw switch, and each of which is provided for every two comb tooth portions PT. In the following description, where necessary, each configuration may be distinguished from the other configurations by adding the subscript "1" to the right of the symbol for the configuration corresponding to comb tooth portion PT1, the subscript "2" to the right of the symbol for the configuration corresponding to comb tooth portion PT2, the subscript "3" to the right of the symbol for the configuration corresponding to comb tooth portion PT3, the subscript "4" to the right of the symbol for the configuration corresponding to comb tooth portion PT4, the subscript "12" to the right of the symbol for the configuration corresponding to both comb tooth portions PT1 and PT2, and the subscript "34" to the right of the symbol for the configuration corresponding to both comb tooth portions PT3 and PT4.

[0073] The common terminal of the switch 601 is connected to the end T1, one selection terminal is connected to the ground terminal, and the other selection terminal constitutes the illustrated node n1. The same is true for the switches 602 to 604, where the common terminal of the switch 602 is connected to the end T2, one selection terminal is connected to the ground terminal, and the other selection terminal constitutes the illustrated node n2, the common terminal of the switch 603 is connected to the end T3, one selection terminal is connected to the ground terminal, and the other selection terminal constitutes the illustrated node n3, and the common terminal of the switch 604 is connected to the end T4, one selection terminal is connected to the ground terminal, and the other selection terminal constitutes the illustrated node n4.

[0074] Switch 61 12 The common terminal of the differential amplifier 40 is connected to the node n2, one selection terminal of the differential amplifier 40 is connected to the node n1, and the other selection terminal of the differential amplifier 40 is connected to a second selection terminal of the switch 621. 12 The common terminal of the switch 622 is connected to the non-inverting input terminal of the differential amplifier 40, the first selection terminal is connected to the node n1, and the third selection terminal is connected to the ground terminal. 12 The first selection terminal is connected to the inverting input terminal of the first transistor n1, the second selection terminal is connected to the node n2, the third selection terminal is connected to the ground terminal.

[0075] Switch 61 34 The common terminal of the differential amplifier 40 is connected to a node n4, one selection terminal of the differential amplifier 40 is connected to a node n3, and the other selection terminal of the differential amplifier 40 is connected to a second selection terminal of the switch 623. 34 The common terminal of the switch 624 is connected to the non-inverting input terminal of the differential amplifier 40, the first selection terminal is connected to the node n3, and the third selection terminal is connected to the ground terminal. 34 A first selection terminal of the switch 624 is connected to the inverting input terminal of the switch 624, a first selection terminal of the switch 624 is connected to the node n4, and a third selection terminal of the switch 624 is connected to the ground terminal. Although not shown, a second selection terminal of the switch 624 is connected to the other selection terminal of the switch 60 corresponding to the other comb tooth portion PT adjacent to the comb tooth portion PT4 on the opposite side to the comb tooth portion PT3.

[0076] With the above configuration, the switch circuit 30 changes the connection destination of the end T2 (first end) to the differential amplifier 40. 12 The sensor controller 31 controls this switching to switch the end T2 between the inverting input terminal (second input terminal) of the differential amplifier 401 and the non-inverting input terminal (first input terminal) of the differential amplifier 401. 12 A first state in which the end T2 is connected to the inverting input terminal of the differential amplifier 40 12 The first state is connected to the non-inverting input terminal of the first input terminal, and the second state is connected to the non-inverting input terminal of the second input terminal of the first input terminal.

[0077] 7 shows a first state of the switch circuit 30. As shown in the figure, in the first state, the end T1 of the comb tooth portion PT1 is connected to the differential amplifier 40 12 and the end T2 of the comb tooth portion PT2 is connected to the non-inverting input terminal of the differential amplifier 40 12 The end T3 of the comb tooth portion PT3 is connected to the inverting input terminal of the differential amplifier 40. 34 and the end T4 of the comb tooth portion PT4 is connected to the non-inverting input terminal of the differential amplifier 40 34 The inverting input terminal of the comb tooth portion PT is connected to the inverting input terminal of the base portion PB. The same applies to the other comb tooth portions PT not shown. As a result, as shown by the dashed lines in FIG. 7, one virtual loop coil is formed by the portions connecting the two adjacent comb tooth portions PT and the base portion PB. Hereinafter, the virtual loop coil thus formed will be referred to as a "virtual loop coil." Although the virtual loop coils are connected through the base portion PB, research by the inventors of the present application has revealed that this does not substantially affect the reception characteristics of the pen signal.

[0078] 8 shows the second state of the switch circuit 30. As shown in the figure, in the second state, the end T2 of the comb tooth portion PT2 is connected to the differential amplifier 40. 12 and the end T3 of the comb tooth portion PT3 is connected to the non-inverting input terminal of the differential amplifier 40 12 The end T1 of the comb tooth portion PT1 is connected to the inverting input terminal of the differential amplifier 40 together with the end of another comb tooth portion PT adjacent to the comb tooth portion PT1 on the opposite side to the comb tooth portion PT2. 34 On the other side of the differential amplifier 12 Similarly, the end T4 of the comb tooth portion PT4 is connected to the differential amplifier 40 adjacent to the comb tooth portion PT4 on the opposite side to the comb tooth portion PT3. 348. The same applies to the other comb tooth portions PT not shown. As a result, as shown by the dashed lines in Fig. 8, one virtual loop coil is formed by the portion connecting two adjacent comb tooth portions PT and the base portion PB, as in the case of Fig. 7, but the combination of two comb tooth portions PT constituting each virtual loop coil is shifted by one comb tooth portion PT in the x direction compared to the case of Fig. 7. In the second state, each virtual loop coil is also connected through the base portion PB, but as in the first state, there is no substantial effect on the reception characteristics of the pen signal.

[0079] When a pen signal is received only in either the first state shown in Fig. 7 or the second state shown in Fig. 8, the interval between the virtual loop coils in the x direction is wide, and the detection accuracy of the pen position in the x direction becomes low. According to the switch circuit 30 of this embodiment, the sensor controller 31 can execute the reception of the pen signal in the first state and the reception of the pen signal in the second state for each loop coil LCy in a time-division manner, so that the interval between the virtual loop coils can be made zero as a whole. Therefore, it can be said that it is possible to improve the detection accuracy of the pen position when the comb coil CCx is used as the receiving coil of the EMR sensor.

[0080] As described above, according to the position detection system 1 of this embodiment, reception of a pen signal in a first state and reception of a pen signal in a second state can be executed in a time-division manner, and therefore the spacing between the virtual loop coils can be effectively set to zero, thereby making it possible to improve the detection accuracy of the pen position when the comb coil CCx is used as the receiving coil of the EMR sensor.

[0081] In the present embodiment, an example has been described in which one comb-tooth portion PT is connected to one input terminal of the differential amplifier 40, but multiple comb-tooth portions PT may be connected. Two modified examples that employ such connections will be described below.

[0082] 9 and 10 are diagrams showing a first state and a second state of the switch circuit 30 according to a first modified example of the present embodiment, respectively. This modified example is an example in which two comb-tooth portions PT are connected to one input terminal of a differential amplifier 40. Note that in these figures, detailed configurations within the switch circuit 30 are not shown, and only the connection state between each comb-tooth portion PT and the differential amplifier 40 is shown. The switch circuit 30 according to this modified example has one differential amplifier 40 for every four comb-tooth portions PT.

[0083] The sensor controller 31 according to this modification first selects four comb tooth portions PT from each of the multiple comb tooth portions PT constituting the comb coil CCx, starting from one end in the x direction, as one set. In the example of FIG. 9, the comb tooth portions PT1 to PT4 and the comb tooth portions PT5 to PT8 each constitute one set. Then, the sensor controller 31 commonly connects two of the four comb tooth portions PT constituting each set from one end in the x direction to the non-inverting input terminal of the corresponding differential amplifier 40, and commonly connects the other two to the inverting input terminal of the corresponding differential amplifier 40. As a result, a state (first state) in which four adjacent comb tooth portions PT are connected to one differential amplifier 40 is formed, as shown in FIG. 9. In this state, a predetermined number (two in this case) of ends including end T4 (first end) of comb tooth portion PT4 are connected to the inverting input terminal of the first differential amplifier 40, and the predetermined number of ends including end T5 (second end) of comb tooth portion PT5 are connected to the non-inverting input terminal of the second differential amplifier 40.

[0084] Next, the sensor controller 31 shifts the four comb tooth portions PT constituting each set one by one. FIG. 10 shows a state where this shift has been performed from the state of FIG. 9. As shown in the figure, in this case, the comb tooth portions PT2 to PT5 and the comb tooth portions PT6 to PT7 each constitute one set. Then, the sensor controller 31, as in the case of FIG. 9, commonly connects two of the four comb tooth portions PT constituting each set from one end side in the x direction to the non-inverting input terminal of the corresponding differential amplifier 40, and commonly connects the other two to the inverting input terminal of the corresponding differential amplifier 40. As a result, as shown in FIG. 10, a state (second state) in which four adjacent comb tooth portions PT are connected to one differential amplifier 40 is formed. In this state, the predetermined number of ends including end T4 (first end) of comb tooth portion PT4 and end T5 (second end) of comb tooth portion PT5 are connected to the inverting input terminal of the first differential amplifier 40, and the other ends of the predetermined number of comb tooth portions PT are connected to the non-inverting input terminal of the second differential amplifier 40.

[0085] The sensor controller 31 according to this modification performs a similar shift three times to form sets of four comb tooth portions PT in four combinations, and performs a process of commonly connecting two of the four comb tooth portions PT constituting each set from one end side in the x direction to the non-inverting input terminal of the corresponding differential amplifier 40, and commonly connecting the other two to the inverting input terminal of the corresponding differential amplifier 40. As a result, four adjacent comb tooth portions PT are connected to one differential amplifier 40 in four states including the first state and the second state described above. The sensor controller 31 according to this modification receives pen signals output from each differential amplifier 40 in each of the four states thus formed. Then, the received pen signals are used to detect the pen position and acquire pen data.

[0086] 11 and 12 are diagrams showing a first state and a second state of the switch circuit 30 according to a second modified example of the present embodiment, respectively. This modified example is an example in which four comb-tooth portions PT are connected to one input terminal of a differential amplifier 40. In these figures, the detailed configuration within the switch circuit 30 is also omitted, and only the connection state between each comb-tooth portion PT and the differential amplifier 40 is shown. The switch circuit 30 according to this modified example has one differential amplifier 40 for every eight comb-tooth portions PT.

[0087] The sensor controller 31 according to this modification first selects eight comb tooth portions PT constituting the comb coil CCx as one set, eight of which are arranged from one end side in the x direction. In the example of FIG. 11, the comb tooth portions PT1 to PT8 constitute one set. Then, the sensor controller 31 commonly connects four of the eight comb tooth portions PT constituting each set from one end side in the x direction to the non-inverting input terminal of the corresponding differential amplifier 40, and commonly connects the other four to the inverting input terminal of the corresponding differential amplifier 40. As a result, as shown in FIG. 11, a state (first state) in which eight adjacent comb tooth portions PT are connected to one differential amplifier 40 is formed. In this state, a predetermined number of ends (four in this case) including the end T8 (first end) of the comb tooth portion PT8 are connected to the inverting input terminal of the first differential amplifier 40, and the predetermined number of ends including the end T9 (second end) of the comb tooth portion PT9 are connected to the non-inverting input terminal of the second differential amplifier 40.

[0088] Next, the sensor controller 31 shifts the eight comb-tooth portions PT constituting each set one by one. Fig. 12 shows the state after this shift from the state of Fig. 11. As shown in the figure, in this case, the comb-tooth portions PT2 to PT 1011, the sensor controller 31 commonly connects four of the eight comb tooth portions PT constituting each set from one end side in the x direction to the non-inverting input terminal of the corresponding differential amplifier 40, and commonly connects the other four to the inverting input terminal of the corresponding differential amplifier 40. As a result, as shown in FIG. 12, a state (second state) in which eight adjacent comb tooth portions PT are connected to one differential amplifier 40 is formed. In this state, the predetermined number of ends including the end T8 (first end) of the comb tooth portion PT8 and the end T9 (second end) of the comb tooth portion PT9 are connected to the inverting input terminal of the first differential amplifier 40, and the other ends of the predetermined number of comb tooth portions PT are connected to the non-inverting input terminal of the second differential amplifier 40.

[0089] The sensor controller 31 according to this modification performs the same shift seven times to form sets of eight comb tooth portions PT in eight combinations, and performs a process of commonly connecting four of the eight comb tooth portions PT constituting each set from one end side in the x direction to the non-inverting input terminal of the corresponding differential amplifier 40, and commonly connecting the other four to the inverting input terminal of the corresponding differential amplifier 40. As a result, eight adjacent comb tooth portions PT are connected to one differential amplifier 40 in eight states including the first state and the second state described above. The sensor controller 31 according to this modification receives pen signals output from each differential amplifier 40 in each of the eight states thus formed. Then, the received pen signals are used to detect the pen position and acquire pen data.

[0090] As shown in the two modified examples described above, according to the position detection system 1 of this embodiment, even when multiple comb-tooth portions PT are connected to one input terminal of the differential amplifier 40, reception of the pen signal in multiple connection states can be executed in a time-division manner. Therefore, it is possible to improve the detection accuracy of the pen position when the comb coil CCx is used as the receiving coil of the EMR sensor. Furthermore, according to these modified examples, since multiple comb-tooth portions PT are connected to one input terminal of the differential amplifier 40, it is possible to increase the reception strength of the pen signal compared to this embodiment.

[0091] Next, a position detection system 1 according to a third embodiment of the present invention will be described. The position detection system 1 according to this embodiment differs from the first embodiment in the internal configuration of the switch circuit 30. Since the position detection system 1 according to this embodiment is otherwise similar to the position detection system 1 according to the first embodiment, the following description will focus on the differences from the position detection system 1 according to the first embodiment.

[0092] 13 is a diagram showing the internal configuration of the switch circuit 30 according to the present embodiment. Only the configuration related to the illustrated loop coil LCx is shown in the figure. Also shown in the figure are one each of the loop coils LCx and LCy and a sensor controller 31.

[0093] As shown in FIG. 13, the switch circuit 30 according to the present embodiment includes a differential amplifier 40, wirings L1 and L2, and a switch group including switch elements S1, S2, T1, and T2 for each loop coil LCx.

[0094] The differential amplifier 40 is an amplifier circuit (differential amplifier) ​​that has a non-inverting input terminal, an inverting input terminal, and an output terminal, amplifies the potential difference between the non-inverting input terminal and the inverting input terminal, and outputs the amplified potential difference from the output terminal as an output voltage with respect to the ground potential. The output signal of the differential amplifier 40 is supplied to the sensor controller 31 as a pen signal PS.

[0095] The wiring L1 connects one end of the loop coil LCx to the corresponding non-inverting input terminal of the differential amplifier 40. The switch element T1 is a single-pole, single-throw switch provided in the middle of this wiring L1. When the switch element T1 is on, one end of the loop coil LCx is connected to the non-inverting input terminal of the differential amplifier 40, whereas when the switch element T1 is off, one end of the loop coil LCx is disconnected from the non-inverting input terminal of the differential amplifier 40.

[0096] The wiring L2 connects the other end of the loop coil LCx to the inverting input terminal of the corresponding differential amplifier 40. The switch element T2 is a single-pole, single-throw switch provided in the middle of this wiring L2. When the switch element T2 is on, the other end of the loop coil LCx is connected to the inverting input terminal of the differential amplifier 40, whereas when the switch element T2 is off, the other end of the loop coil LCx is disconnected from the inverting input terminal of the differential amplifier 40.

[0097] The switch element S1 is a single-pole, single-throw switch provided between a power supply wiring to which a predetermined power supply potential Vref (e.g., a ground potential or an intermediate potential of a pen signal) is supplied and a portion of the wiring L1 between the switch element T1 and the loop coil LCx, and serves to supply the power supply potential Vref to one end of the loop coil LCx. Similarly, the switch element S2 is a single-pole, single-throw switch provided between a power supply wiring to which a predetermined power supply potential Vref is supplied and a portion of the wiring L2 between the switch element T2 and the loop coil LCx, and serves to supply the power supply potential Vref to the other end of the loop coil LCx.

[0098] The switch elements S1 and S2 are controlled by a precharge signal pre generated by the sensor controller 31. The switch elements T1 and T2 are controlled by a selection signal sel generated by the sensor controller 31. The control of the switch elements S1, S2, T1, and T2 performed by the sensor controller 31 using these signals will be described in detail below.

[0099] FIG. 14 is a diagram showing waveforms of signals related to the control of switch elements S1, S2, T1, and T2. The voltage PE shown in the figure is the voltage across both ends of the coil constituting the resonance circuit of the electromagnetic induction pen 2. When the sensor controller 31 starts sending an alternating magnetic field from the loop coil LCy at time t1, the voltage PE rises in the electromagnetic induction pen 2 located in the vicinity thereof as shown in the figure. The sensor controller 31 continues to send this alternating magnetic field from time t1 to time t3, which is a predetermined time Ta after time t1.

[0100] At time t2 (the time after a predetermined time Tb (<Ta) from time t1) while the sensor controller 31 continues to send the alternating magnetic field, the precharge signal pre is activated. As a result, the switch elements S1 and S2 shown in FIG. 13 turn on, and the supply of the power supply potential Vref to the loop coil LCx is started. The sensor controller 31 maintains the precharge signal pre in the active state until time t3 or immediately before that time, and then returns the precharge signal pre to the inactive state. By performing this series of processes, each loop coil LCx can be precharged, so that the influence of the alternating magnetic field sent from the loop coil LCy can be eliminated from the loop coil LCx, and the SNR of the pen signal PS can be improved.

[0101] Here, as shown in FIG. 13, the switch circuit 30 is configured such that the power supply potential Vref is supplied to each of one end and the other end of the loop coil LCx in order to complete the precharge in a shorter time. That is, since the loop coil LCx has a time constant as described above, when the power supply potential Vref is supplied to the loop coil LCx, the whole does not immediately become the power supply potential Vref, but gradually transitions to the power supply potential Vref over a certain period of time starting from the portion close to the power supply wiring. Therefore, if the power supply potential Vref is supplied to both one end and the other end of the loop coil LCx, this time can be shortened. However, the configuration of supplying the power supply potential Vref to both one end and the other end of the loop coil LCx is not essential, and it may be configured to supply the power supply potential Vref to only one of them.

[0102] Returning to Fig. 14, the sensor controller 31 stops transmitting the alternating magnetic field at time t3, and at the same time activates the selection signal sel to turn on the switch elements T1 and T2. Then, the alternating magnetic field transmitted from the electromagnetic induction pen 2 generates an alternating current in the loop coil LCx, which is supplied to the sensor controller 31 as the pen signal PS as shown in the figure. This enables the sensor controller 31 to obtain the pen position and pen data based on the pen signal PS. The sensor controller 31 maintains the selection signal sel in an active state until time t4 when it starts transmitting the alternating magnetic field again, and then returns the selection signal sel to an inactive state. The subsequent processing is a repetition of the processing described up to this point.

[0103] As described above, according to the switch circuit 30 and the sensor controller 31 of this embodiment, each loop coil LCx can be precharged by turning on the switch elements S1 and S2, so that the influence of the alternating magnetic field sent from the transmitting loop coil LCy can be eliminated from each receiving loop coil LCx, thereby improving the SNR of the pen signal PS.

[0104] Fig. 15 is a diagram showing a method of driving an EMR sensor according to a modification of this embodiment. The sensor controller 31 according to this modification differs from the sensor controller 31 according to this embodiment in that, when performing the above-mentioned global scan, the sensor controller 31 receives pen signals from only half of the multiple loop coils LCx, not all of them, each time an AC current is passed through each loop coil LCy. The following description will focus on the differences. Note that, for the sake of simplicity, Fig. 15 shows only six loop coils LCx and LCy, but the same applies to cases where the EMR sensor includes more loop coils LCx and LCy.

[0105] Fig. 15(a) shows a first reception mode of the pen signal, and Fig. 15(b) shows a second reception mode of the pen signal. The sensor controller 31 according to this modification detects the pen position by alternately performing the first reception mode and the second reception mode.

[0106] As a premise, the switch circuit 30 according to this modified example is configured so that the switch elements T1, T2 are controlled by different selection signals sel for the 2n-1th (n is a natural number; odd-numbered) loop coil LCx from one end in the x direction among the multiple loop coils LCx and the 2nth (even-numbered) loop coil LCx from one end in the x direction among the multiple loop coils LCx. As a result, the switch circuit 30 of this modified example is configured to be able to switch between a first state in which one end and the other end of the 2n-1th (odd-numbered) loop coil LCx from one end side in the x direction among the multiple loop coils LCx are connected to the non-inverting input terminal and inverting input terminal of the corresponding differential amplifier 40, while one end and the other end of the 2n-th (even-numbered) loop coil LCx are disconnected from the non-inverting input terminal and inverting input terminal of the corresponding differential amplifier 40, and a second state in which one end and the other end of the 2n-th (even-numbered) loop coil LCx from one end side in the x direction among the multiple loop coils LCx are connected to the non-inverting input terminal and inverting input terminal of the corresponding differential amplifier 40, while one end and the other end of the 2n-1th (odd-numbered) loop coil LCx are disconnected from the non-inverting input terminal and inverting input terminal of the corresponding differential amplifier 40, in response to control from the sensor controller 31.

[0107] 15(a), the sensor controller 31 sets the switch circuit 30 to the first state when passing an AC current through the 2m-1th (m is a natural number, odd-numbered) loop coil LCy from one end in the y direction among the multiple loop coils LCy, and sets the switch circuit 30 to the second state when passing an AC current through the 2mth (even-numbered) loop coil LCy from one end in the y direction among the multiple loop coils LCy, thereby receiving pen signals output from each of the multiple differential amplifiers 40. According to this process, detection of the pen position is performed centering on the hatched portion in FIG. 15(a).

[0108] On the other hand, in the second reception mode shown in Fig. 15(b), the sensor controller 31 sets the switch circuit 30 to the second state when passing an AC current through the 2m-1th (odd-numbered) loop coil LCy from one end side in the y direction among the multiple loop coils LCy, and sets the switch circuit 30 to the first state when passing an AC current through the 2mth (even-numbered) loop coil LCy from one end side in the y direction among the multiple loop coils LCy, thereby receiving the pen signals output from each of the multiple differential amplifiers 40. According to this process, the detection of the pen position is performed centering on the hatched portion in Fig. 15(b). Compared with Fig. 15(a), it can be seen that hatching has been added to the portion that was not hatched in Fig. 15(a).

[0109] According to this modification, it is possible to detect the pen position with higher accuracy than, for example, in the first reception mode, when the switch circuit 30 is in the first state whenever an AC current is passed through any of the loop coils LCy, and in the second reception mode, when the switch circuit 30 is in the second state whenever an AC current is passed through any of the loop coils LCy. As can be seen from Fig. 15(a) and (b), this is an effect of being able to derive the intensity distribution of the pen signal with higher accuracy in all directions, since hatched parts (i.e., parts where the intensity of the pen signal is acquired) are arranged (i.e., arranged in a grid pattern) above, below, left and right of non-hatched parts (i.e., parts where the intensity of the pen signal is not acquired).

[0110] Furthermore, according to this modification, the number of differential amplifiers 40 used simultaneously is half that of the present embodiment, so it is also possible to halve the number of differential amplifiers 40 provided in the switch circuit 30. For the same reason, it is also possible to halve the number of circuits arranged in the sensor controller 31 for receiving pen signals.

[0111] FIG. 16 is a diagram showing the configuration of a position detection system 1 according to a fourth embodiment of the present invention. The position detection system 1 according to this embodiment differs from the position detection system 1 according to the third embodiment in that a comb coil CCx consisting of a base portion PB and a plurality of comb teeth portions PT is used as the receiving coil of the EMR sensor, instead of a plurality of loop coils LCx. In addition, the internal configuration of the switch circuit 30 and the content of the control of the switch circuit 30 by the sensor controller 31 are also different from those of the position detection system 1 according to the third embodiment. Since the position detection system 1 according to the third embodiment is otherwise similar to the position detection system 1 according to the third embodiment, the following description will focus on the differences from the position detection system 1 according to the third embodiment.

[0112] 16, the comb coil CCx is configured by connecting a base PB, which is a single wire extending in the x direction, to a plurality of comb tooth portions PT, which are wires extending in the y direction. One end of each comb tooth portion PT is connected to the base PB, and the other end is connected to a switch circuit 30.

[0113] 17 and 18 are diagrams showing the internal configuration of the switch circuit 30 according to this embodiment. These diagrams show only the parts of the internal configuration of the switch circuit 30 that are related to reception of pen signals at some of the comb-tooth portions PT. In the following description, the x-th comb-tooth portion PT from one end side in the x direction among the multiple comb-tooth portions PT is referred to as the comb-tooth portion PT. x to distinguish it from the other comb tooth portions PT.

[0114] As shown in Figs. 17 and 18, the switch circuit 30 according to this embodiment is configured to include a plurality of differential amplifiers 50 and a plurality of switches 51, 52. A differential amplifier 50 is provided for every two comb-tooth portions PT, and the switches 51, 52 are provided for each comb-tooth portion PT. The configuration and operation of each differential amplifier 50 are similar to those of the differential amplifier 40 described in the third embodiment. In the following description, the differential amplifiers 50 that are provided for the comb-tooth portions PT x-1 ,PT x The differential amplifier 50 corresponds to the x to distinguish it from other differential amplifiers 50.

[0115] The switch 51 is a single-pole, triple-throw switch. The common terminal of the switch 51 is connected to the other end of the corresponding comb-tooth portion PT. x-1 The first selection terminal of the switch 51 connected to the differential amplifier 50 x-2 the second selection terminal is connected to the open end, and the third selection terminal is connected to the non-inverting input terminal of the differential amplifier 50 x The common terminal is connected to the inverting input terminal of the comb tooth part PT x The first selection terminal of the switch 51 connected to the differential amplifier 50 xthe second selection terminal is connected to the open end, and the third selection terminal is connected to the inverting input terminal of the differential amplifier 50 x This is connected to the non-inverting input terminal of the

[0116] The switch 52 is a single-pole, single-throw switch that is provided between a power supply wiring to which a predetermined power supply potential Vref (e.g., ground potential) is supplied and a wiring that connects the common terminal of the corresponding switch 51 to the comb tooth portion PT, and serves to supply the power supply potential Vref to the corresponding comb tooth portion PT.

[0117] The switches 51 and 52 are controlled by the sensor controller 31. The control of the switch 52 is performed to precharge the comb tooth portion PT, and is performed at the same timing as the control of the switches S1 and S2 described with reference to Fig. 14. In addition, the control of the switch 51 for connecting the common terminal to the second selection terminal (release end) is also performed at the same timing as the timing for turning off the switches T1 and T2 described with reference to Fig. 14. As a result, each differential amplifier 50 is connected to the comb tooth portion PT only during a period when the transmission of the alternating magnetic field from the loop coil LCy is stopped.

[0118] Regarding the timing of connecting the common terminal to the first selection terminal or the third selection terminal in the control of the switch 51, the sensor controller 31 controls so that the interval between virtual loop coils formed in the comb coil CCx is effectively zero in order to detect the pen position with high accuracy even when the comb coil CCx is used as the receiving coil of the EMR sensor. This point will be specifically described below.

[0119] First, the state of the switch circuit 30 will be described. The switch circuit 30 is configured to be switchable between a first state (state shown in FIG. 17) in which the third selection terminal is selected in each switch 51 and a second state (state shown in FIG. 18) in which the first selection terminal is selected in each switch 51 under the control of the sensor controller 31. In the first state, as shown in FIG. 17, the other end of the 2n-1th (n is a natural number; odd-numbered) comb tooth portion PT from one end side in the x direction among the multiple comb tooth portions PT and the other end of the 2nth (even-numbered) comb tooth portion PT are connected to the inverting input terminal and the non-inverting input terminal of the same differential amplifier 50. As a result, a virtual loop coil is formed by the 2n-1th comb tooth portion PT, the 2nth comb tooth portion PT, and a portion of the base portion PB that connects them (the portion circled in FIG. 17). 18, the other end of the 2n-th (even-numbered) comb tooth portion PT and the other end of the 2n+1-th (odd-numbered) comb tooth portion PT from one end side in the x direction among the multiple comb tooth portions PT are connected to the inverting input terminal and the non-inverting input terminal of the same differential amplifier 50. As a result, a virtual loop coil is formed by the 2n-th comb tooth portion PT, the 2n+1-th comb tooth portion PT, and a portion of the base portion PB connecting them (the portion circled in FIG. 18).

[0120] The sensor controller 31 performs the process of starting the supply of AC current to each loop coil LCy, stopping the supply, and then switching the switch circuit 30 to the first state to receive a pen signal, and then starting the supply of AC current to the same loop coil LCy again, stopping the supply, and then switching the switch circuit 30 to the second state to receive a pen signal. This process is common to the global scan and the local scan. This effectively reduces the gap between the virtual loop coils formed by the comb coils CCx to zero in both the global scan and the local scan, thereby improving the detection accuracy of the pen position when the comb coil CCx is used as the receiving coil of the EMR sensor.

[0121] As described above, according to the switch circuit 30 and the sensor controller 31 of this embodiment, reception of a pen signal in the first state and reception of a pen signal in the second state can be executed in a time-division manner. Therefore, the spacing between the virtual loop coils can be effectively set to zero, thereby improving the detection accuracy of the pen position when the comb coil CCx is used as the receiving coil of the EMR sensor.

[0122] Furthermore, according to the switch circuit 30 and the sensor controller 31 of this embodiment, each comb tooth portion PT can be precharged by turning on the switch 52. As a result, similar to the third embodiment, it is possible to eliminate the influence of the alternating magnetic field sent from the loop coil LCy on the transmitting side from each comb tooth portion PT on the receiving side, thereby improving the SNR of the pen signal PS.

[0123] Fig. 19 is a diagram showing a method of driving an EMR sensor according to a modification of this embodiment. The sensor controller 31 according to this modification differs from the sensor controller 31 according to this embodiment in that, when performing one global scan, the sensor controller 31 performs only one of receiving a pen signal using the switch circuit 30 in the first state and receiving a pen signal using the switch circuit 30 in the second state, instead of both, for each loop coil LCy. The following description will focus on the differences. Note that, for the sake of simplicity, Fig. 19 shows only six loop coils LCy and seven comb-tooth portions PT, but the same applies to the case where the EMR sensor includes more loop coils LCy and comb-tooth portions PT.

[0124] Fig. 19(a) shows a first reception mode of the pen signal, and Fig. 19(b) shows a second reception mode of the pen signal. The sensor controller 31 according to this modification detects the pen position by alternately performing a global scan in the first reception mode and a global scan in the second reception mode.

[0125] In the first reception mode, the sensor controller 31 sets the switch circuit 30 to the first state when passing an AC current through the 2m-1th (m is a natural number, odd-numbered) loop coil LCy from one end in the y direction among the multiple loop coils LCy, and sets the switch circuit 30 to the second state when passing an AC current through the 2mth (even-numbered) loop coil LCy from one end in the y direction among the multiple loop coils LCy, thereby receiving pen signals output from each of the multiple differential amplifiers 50. According to this process, detection of the pen position is performed centering on the hatched portion in Fig. 19(a).

[0126] On the other hand, in the second reception mode, the sensor controller 31 sets the switch circuit 30 to the second state when passing an AC current through the 2m-1th (odd-numbered) loop coil LCy from one end side in the y direction among the multiple loop coils LCy, and sets the switch circuit 30 to the first state when passing an AC current through the 2mth (even-numbered) loop coil LCy from one end side in the y direction among the multiple loop coils LCy, thereby receiving the pen signals output from each of the multiple differential amplifiers 50. According to this process, the detection of the pen position is performed centering on the hatched portion in FIG. 19(b). Compared with FIG. 19(a), it can be seen that hatching has been added to the portion that was not hatched in FIG. 19(a).

[0127] According to this modification, it is possible to complete one global scan in half the time compared to the present embodiment. Although the accuracy of the pen position detected in one global scan is lower than that of the present embodiment, since the hatched parts in each global scan are arranged in a lattice pattern similar to the modification of the third embodiment described with reference to Fig. 15, it is possible to detect the pen position with higher accuracy than, for example, a case in which the switch circuit 30 is in the first state when an AC current is passed through any loop coil LCy in the first reception mode, and the switch circuit 30 is in the second state when an AC current is passed through any loop coil LCy in the second reception mode.

[0128] 20 is a diagram showing a configuration of a position detection system 1 according to a fifth embodiment of the present invention. The position detection system 1 according to this embodiment differs from the position detection system 1 according to the fourth embodiment in that the position detection system 1 according to this embodiment uses, as the receiving coil of the EMR sensor, a plurality of linear electrodes LE each extending in the y direction and arranged side by side in the x direction, instead of a comb coil CCx. Since the position detection system 1 according to the fourth embodiment is otherwise similar to the position detection system 1 according to the fourth embodiment, the following description will focus on the differences from the position detection system 1 according to the fourth embodiment.

[0129] In short, the configuration of the EMR sensor according to this embodiment is a configuration in which the base portion PB is removed from the comb coil CCx of the fourth embodiment. FIGS. 21 and 22 are diagrams showing the internal configuration of the switch circuit 30 according to this embodiment. As can be understood by comparing these diagrams with FIGS. 17 and 18, the configuration inside the switch circuit 30 is similar to that inside the switch circuit 30 according to the fourth embodiment, except that the connection destination is the linear electrode LE instead of the comb tooth portion PT. Therefore, the switch circuit 30 according to this embodiment is also configured to be switchable between the first state and the second state described in the fourth embodiment under the control of the sensor controller 31. FIG. 21 shows the first state, and FIG. 22 shows the second state. The reception process of the pen signal performed by the sensor controller 31 using this control may also be similar to that of the fourth embodiment.

[0130] In this embodiment, since each linear electrode LE is electrically isolated, no virtual loop coil is formed as described in the fourth embodiment when the switch circuit 30 is in either the first state or the second state. The coupling between the linear electrode LE and the coil in the electromagnetic induction pen 2 is weaker than the loop coil LCx described in the third embodiment and the comb coil CCx described in the fourth embodiment, so the reception strength of the pen signal received by each linear electrode LE is weaker than in the third and fourth embodiments. However, according to the configuration of the switch circuit 30 according to this embodiment, the reception strength of the pen signal is increased, especially in the vicinity of the pen position. This is because the sign of the pen signal is opposite between the linear electrode LE on one side of the pen position in the x direction and the linear electrode LE on the other side. This point will be described below with reference to a graph of reception strength.

[0131] FIG. 23 is a diagram showing a simulation result of the reception strength of a pen signal. A graph G1 shown in the figure shows a simulation result of the reception strength of a pen signal received by the sensor controller 31 according to this embodiment. On the other hand, a graph G0 shows a simulation result of the reception strength of a pen signal received by the sensor controller 31 in the case of using a position detection device of a type that supplies the pen signal received by each linear electrode LE to the sensor controller 31 alone without using a differential amplifier 50. The horizontal axis of the figure shows the serial number of the linear electrodes LE. The position of each point on the horizontal axis of the graph G1 corresponds to the middle position in the x direction of two linear electrodes LE connected to the same differential amplifier 50. This point is also the same for a graph G2 described later.

[0132] 23 shows an example in which the pen tip of the electromagnetic induction pen 2 is located between the 10th linear electrode LE and the 11th linear electrode LE. Looking first at the graph G0, it can be seen that the sign of the reception strength of the pen signal received by the 10th or lower linear electrodes LE is opposite to that of the reception strength of the pen signal received by the 11th or lower linear electrodes LE, and that in the vicinity of the pen position, the reception strength of the pen signal becomes weak to almost zero.

[0133] Next, looking at graph G1, it can be seen that a normal distribution-like distribution with a peak at the pen position can be obtained. Such a distribution is obtained because pen signals of opposite signs are reinforced by the differential amplifier 50. From this result, it can be seen that the position detection device 3 according to this embodiment has the effect of increasing the reception strength of the pen signal in the vicinity of the pen position.

[0134] As described above, according to the position detection device 3 of this embodiment, pen signals having opposite signs are reinforced by the differential amplifier 50, so that it is possible to increase the received strength of the pen signal in the vicinity of the pen position when the linear electrode LE is used as an Rx coil.

[0135] 24 and 25 are diagrams showing the internal configuration of a switch circuit 30 according to a first modified example of the present embodiment. FIG. 24 shows a first state, and FIG. 25 shows a second state. As can be seen by comparing FIG. 24 and FIG. 25 with FIG. 21 and FIG. 22, the switch circuit 30 according to this modified example has the same differential amplifier 50. x The switch circuit 30 differs from the switch circuit 30 according to the present embodiment in that the two linear electrodes LE connected to the sensor 10 are not directly adjacent to each other, but are adjacent to each other with the two linear electrodes LE sandwiched therebetween. In other respects, the switch circuit 30 is the same as the switch circuit 30 according to the present embodiment, and the content of the control of the switch circuit 30 by the sensor controller 31 is also the same as that according to the present embodiment.

[0136] The switch circuit 30 according to this modification is configured to be switchable between a first state in which an end of the 2n-kth (k=3, n is a natural number greater than k / 2) linear electrode LE from one end side in the x direction and an end of the 2nth linear electrode LE from among the plurality of linear electrodes LE are connected to the inverting input terminal and the non-inverting input terminal of the same differential amplifier 50, respectively, and a second state in which an end of the 2nth linear electrode LE from one end side in the x direction and an end of the 2n+kth linear electrode LE from among the plurality of linear electrodes LE are connected to the inverting input terminal and the non-inverting input terminal of the same differential amplifier 50, respectively. In this modification, k=3, but if k=1, the switch circuit 30 described in the present embodiment is obtained. Generally speaking, k may be any natural number that is an odd number, and the value of k that maximizes the reception strength of the pen signal in the vicinity of the pen position may be selected.

[0137] 23 shows a simulation result of the reception strength of the pen signal received by the sensor controller 31 according to this modification. As can be seen from a comparison with graph G1, the switch circuit 30 according to this modification obtains a normal distribution-like shape having a peak at the pen position, similar to graph G1, and the peak reception strength is greater than that of graph G1. Therefore, it can be said that the position detection device 3 according to this modification can further increase the reception strength of the pen signal in the vicinity of the pen position when the linear electrode LE is used as an Rx coil.

[0138] Fig. 26 is a diagram showing a method of driving an EMR sensor according to a second modified example of this embodiment. The sensor controller 31 according to this modified example differs from the sensor controller 31 according to this embodiment in that, when performing one global scan, the sensor controller 31 performs only one of receiving a pen signal using the switch circuit 30 in the first state and receiving a pen signal using the switch circuit 30 in the second state, instead of both, for each loop coil LCy. The following description will focus on the differences. Note that, for the sake of simplicity, Fig. 26 shows only six loop coils LCy and seven linear electrodes LE, but the same applies to the case where the EMR sensor includes more loop coils LCy and linear electrodes LE.

[0139] Fig. 26(a) shows a first reception mode of the pen signal, and Fig. 26(b) shows a second reception mode of the pen signal. The sensor controller 31 according to this modification detects the pen position by alternately performing a global scan in the first reception mode and a global scan in the second reception mode.

[0140] In the first reception mode, the sensor controller 31 sets the switch circuit 30 to the first state when passing an AC current through the 2m-1th (m is a natural number, odd-numbered) loop coil LCy from one end in the y direction among the multiple loop coils LCy, and sets the switch circuit 30 to the second state when passing an AC current through the 2mth (even-numbered) loop coil LCy from one end in the y direction among the multiple loop coils LCy, thereby receiving pen signals output from each of the multiple differential amplifiers 50. According to this process, detection of the pen position is performed centering on the hatched portion in Fig. 26(a).

[0141] On the other hand, in the second reception mode, the sensor controller 31 sets the switch circuit 30 to the second state when passing an AC current through the 2m-1th (odd-numbered) loop coil LCy from one end side in the y direction among the multiple loop coils LCy, and sets the switch circuit 30 to the first state when passing an AC current through the 2mth (even-numbered) loop coil LCy from one end side in the y direction among the multiple loop coils LCy, thereby receiving the pen signals output from each of the multiple differential amplifiers 50. According to this process, the detection of the pen position is performed centering on the hatched portion in FIG. 26(b). When compared with FIG. 26(a), it can be seen that hatching has been added to the portion that was not hatched in FIG. 26(a).

[0142] According to this modification, it is possible to complete one global scan in half the time compared to the present embodiment. Although the accuracy of the pen position detected in one global scan is lower than that of the present embodiment, since the hatched parts in each global scan are arranged in a lattice pattern similar to the modification of the third embodiment described with reference to Fig. 15, it is possible to detect the pen position with higher accuracy than, for example, a case in which the switch circuit 30 is in the first state when an AC current is passed through any loop coil LCy in the first reception mode, and the switch circuit 30 is in the second state when an AC current is passed through any loop coil LCy in the second reception mode.

[0143] Next, a position detection system 1 according to a sixth embodiment of the present invention will be described. The position detection system 1 according to this embodiment differs from the third embodiment in terms of the internal processing of the sensor controller 31. Since the position detection system 1 according to this embodiment is otherwise similar to the position detection system 1 according to the third embodiment, the following description will focus on the differences from the position detection system 1 according to the third embodiment.

[0144] Fig. 27 is a diagram showing problems that arise when a pen signal is received using the position detection system 1 according to the third embodiment. Fig. 28 is a diagram for explaining the azimuth angle θ and tilt angle φ used in Fig. 27. Before explaining the position detection system 1 according to this embodiment, problems that are solved by the position detection system 1 according to this embodiment will be explained below with reference to these diagrams.

[0145] As shown in FIG. 28, three angles are defined for the electromagnetic induction pen 2: an azimuth angle θ, a tilt angle φ, and a rotation angle ψ. The azimuth angle θ is an angle representing the direction in which the tip of the electromagnetic induction pen 2 in contact with the touch surface 3a points, and is represented by the angle between a predetermined axis set in the touch surface 3a and the projection of the pen axis of the electromagnetic induction pen 2 onto the touch surface 3a. The tilt angle φ is an angle representing the inclination of the electromagnetic induction pen 2 with respect to the touch surface 3a, and is represented by the angle between the pen axis of the electromagnetic induction pen 2 and the touch surface 3a. The rotation angle ψ is an angle representing the amount of rotation of the electromagnetic induction pen 2 itself around the pen axis. The problem to be solved by the position detection system 1 according to this embodiment relates to the azimuth angle θ and the tilt angle φ among these angles.

[0146] 27 shows the reception level of the pen signal PS received by the loop coil LCx corresponding to each x coordinate when the pen tip of the electromagnetic induction pen 2 is at the position of x coordinate = 0 mm, and the azimuth angle θ and tilt angle φ are (θ,φ) = (0°,0°), (0°,60°), (180°,60°), (90°,60°), respectively. As shown in the figure, when (θ,φ) = (0°,0°) (90°,60°), the peak of the reception level of the pen signal PS is at the position of x coordinate = 0 mm, while when (θ,φ) = (0°,60°), the peak position of the reception level of the pen signal PS is shifted to the negative side. Also, when (θ,φ) = (180°,60°), the peak position of the reception level of the pen signal PS is shifted to the positive side. As described above, in the position detection system 1 according to the third embodiment, the peak position of the reception level of the pen signal PS may shift from the original position of the pen tip depending on the combination of the azimuth angle θ and the tilt angle φ of the electromagnetic induction pen 2. The position detection system 1 according to the present embodiment is intended to improve the deterioration of the detection accuracy of the pen position caused by such a shift.

[0147] 29(a) is a diagram for explaining the process performed by the sensor controller 31 according to the present embodiment. As shown in the figure, the sensor controller 31 according to the present embodiment controls the n-th loop coil LCx n The pen signal PS received at n and loop coil LCx n and a pen signal PS received by each of one or more loop coils LCx in the vicinity of the SUM The position of the electromagnetic induction pen 2 is derived using the above.

[0148] Specifically, the sensor controller 31 according to the present embodiment is configured to: n-2 ~n+2nd loop coil LCx n+2 The pen signal PS received at the five loop coils LCx n-2 ~PS n+2The pen signal PS received at the three loop coils LCx located at the center of the five loop coils LCx is n-1 ~PS n+1 The weighting of the pen signal received at the other two loop coils LCx is n-2 ,PS n+2 The above addition is performed so that the weighting of PS SUM =PS n-2 +2 PS n-1 +2 PS n +2 PS n+1 +PS n+2 It becomes.

[0149] Fig. 29(b) is a diagram showing a virtual loop coil VLCx obtained by the addition shown in Fig. 29(a). As shown in the figure, the added pen signal PS SUM is a signal equivalent to the pen signal PS received by a double-wound coil with an inner wiring width of X1 (the width of three loop coils LC) and a distance between the outer wiring and the inner wiring of X2 (the width of one loop coil LC).

[0150] FIG. 30 shows the additive pen signal PS when the tip of the electromagnetic induction pen 2 is at the x coordinate = 0 mm. SUM 27, the figure shows the reception level of the additive pen signal PS obtained at the loop coil LCx corresponding to each x coordinate when the azimuth angle θ and the tilt angle φ are (θ, φ)=(0°, 0°), (0°, 60°), (180°, 60°), and (90°, 60°), respectively. SUM 13 shows the reception level of the signal obtained by weighting and adding the pen signals PS received by the five loop coils LCx centered around that loop coil LCx.

[0151] As shown in FIG. 30, the additive pen signal PS SUM The peak position of the reception level of the added pen signal PS is at the position of x coordinate = 0 mm, regardless of the azimuth angle θ and tilt angle φ of the electromagnetic induction pen 2. When (θ, φ) = (90°, 60°), the added pen signal PS SUMHowever, since the shape is symmetrical, this depression does not deteriorate the detection accuracy of the pen position. Therefore, according to the position detection system 1 of this embodiment, even if the electromagnetic induction pen 2 is tilted with respect to the touch surface 3a, it can be said that the position can be detected with high accuracy.

[0152] As described above, according to the position detection system 1 of this embodiment, the pen signals PS received by the multiple loop coils LCx are added with different weights to generate the sum pen signal PS SUM Since the position of the electromagnetic induction pen 2 is derived using the above, even if the electromagnetic induction pen 2 is tilted with respect to the touch surface 3a, the position can be detected with high accuracy.

[0153] Next, a position detection system 1 according to a seventh embodiment of the present invention will be described. The position detection system 1 according to this embodiment differs from the fourth embodiment in that the position detection device 3 is a smartphone with a built-in foldable display, in the internal configuration of the switch circuit 30, and in the internal processing of the sensor controller 31. Since the position detection system 1 according to this embodiment is otherwise similar to the position detection system 1 according to the fourth embodiment, the following description will focus on the differences from the position detection system 1 according to the fourth embodiment.

[0154] In the following description, the position detection method of the electromagnetic induction pen 2 realized by the switch circuit 30 and the sensor controller 31 according to the fourth embodiment may be referred to as the "ODD / EVEN method." "ODD" and "EVEN" respectively correspond to the first state and the second state of the switch circuit 30 described in the fourth embodiment. Also, the position detection method of the electromagnetic induction pen 2 realized by the switch circuit 30 and the sensor controller 31 according to this embodiment may be referred to as the "A / B / C method." As will be described in detail later, the switch circuit 30 according to this embodiment is configured to be switchable between three states, from a first state to a third state, and "A," "B," and "C" respectively correspond to the first state to the third state.

[0155] Fig. 31(a) is a plan view of an EMR sensor 33 included in the position detection device 3 according to this embodiment, and Fig. 31(b) is a cross-sectional view of the EMR sensor 33 corresponding to the line AA shown in Fig. 31(a). As shown in these figures, the EMR sensor 33 is configured to have a substrate 34 on which a receiving coil and a transmitting coil are formed, and a magnetic material sheet 35 made of a magnetic material. The magnetic material sheet 35 is a member that functions as a magnetic path for the magnetic field generated by the coil in the substrate 34, and is arranged so as to cover the entire one surface of the substrate 34 (the surface opposite to the touch surface 3a).

[0156] If a display (not shown) included in the position detection device 3 is a foldable display, it is necessary to configure the EMR sensor 33 to be foldable as well. The illustrated component 36 is a conductive hinge component required for this purpose, and is disposed between the substrate 34 and the magnetic sheet 35 along the folding line FL.

[0157] FIG. 32(a) is a diagram illustrating the distribution of the reception level of the pen signal PS received when the tip of the electromagnetic induction pen 2 is at each position in the x direction, assuming that the ODD / EVEN method is adopted in the position detection device 3 according to this embodiment. As shown in the figure, according to the ODD / EVEN method, the reception level of the pen signal PS drops significantly near the folding line FL. This is because the magnetic field is disturbed by the hinge part 36 shown in FIG. 31(a)(b). With the reception level as shown in FIG. 32(a), it is difficult to derive the pen position near the folding line FL, and it has been necessary to improve the reception level of the pen signal PS near the folding line FL. The position detection system 1 according to this embodiment aims to realize such an improvement in the reception level of the pen signal PS by using the A / B / C method instead of the ODD / EVEN method.

[0158] 33 to 35 are diagrams showing the internal configuration of the switch circuit 30 according to this embodiment. As in FIGS. 17 and 18, these diagrams show only the parts of the internal configuration of the switch circuit 30 that are related to reception of pen signals at some of the comb-tooth portions PT. In the following description, the x-th comb-tooth portion PT from one end side in the x direction among the multiple comb-tooth portions PT is referred to as the comb-tooth portion PT. x to distinguish it from the other comb tooth portions PT.

[0159] As shown in FIGS. 33 to 35, the switch circuit 30 according to the present embodiment has a differential amplifier 50 at a ratio of one to every three comb-tooth portions PT. In the following description, the differential amplifiers 50 are x-1 ,PT x ,PT x+1 The differential amplifier 50 corresponds to the x to distinguish it from other differential amplifiers 50.

[0160] The common terminal of the switch 51 according to the present embodiment is connected to the other end of the corresponding comb tooth portion PT. x The first selection terminal of the switch 51 connected to the differential amplifier 50 x the second selection terminal is connected to the open end, and the third selection terminal is connected to the inverting input terminal of the differential amplifier 50 x The common terminal is connected to the non-inverting input terminal of the comb tooth part PT x-1 The first selection terminal of the switch 51 connected to the differential amplifier 50 x the second selection terminal is connected to the open end, and the third selection terminal is connected to the inverting input terminal of the differential amplifier 50 x-2 The common terminal is connected to the non-inverting input terminal of the comb tooth part PT x+1 The first selection terminal of the switch 51 connected to the differential amplifier 50 x+2 the second selection terminal is connected to the open end, and the third selection terminal is connected to the inverting input terminal of the differential amplifier 50 x The above configuration is connected to the non-inverting input terminal of the differential amplifier 50. x To summarize from the side, the differential amplifier 50 x The inverting input terminal of the comb tooth part PT x-2 ,PTx-1 ,PT x The first selection terminals of the three switches 51 corresponding to x The non-inverting input terminal of the comb tooth part PT x ,PT x+1 ,PT x+2 The third selection terminals of the three switches 51 corresponding to these three switches are connected in common.

[0161] The switch circuit 30 according to the present embodiment has five comb tooth portions PT (differential amplifier 50) corresponding to each differential amplifier 50. x If so, comb tooth part PT x-2 ,PT x-1 ,PT x ,PT x+1 ,PT x+2 The comb tooth portion PT functions as a selection circuit that selects two of the five) according to the control of the sensor controller 31 and connects the selected two comb tooth portions PT to a differential amplifier 50 serving as a receiving circuit.

[0162] The sensor controller 31 according to the present embodiment includes, for example, a differential amplifier 50 x Regarding this, the comb tooth part PT x-2 ,PT x A first state in which the comb tooth portion PT x-1 ,PT x+1 A second state in which the comb tooth portion PT x ,PT x+2 The sensor controller 31 controls the switch circuit 30 so that the first state, the second state, and the third state, which selects the first state, appear in sequence. That is, the sensor controller 31 according to this embodiment fulfills the role of realizing the above-mentioned A / B / C method. After controlling the multiple switches 51 so that the third state appears, the sensor controller 31 repeats the same control from the first state. The same is true for the other differential amplifiers 50, and the sensor controller 31 controls the differential amplifiers 50 x The switch circuit 30 is controlled so that the state of each switch 51 corresponding to the differential amplifier 50 and the state of each switch 51 corresponding to the other differential amplifier 50 are synchronized and become the same state.

[0163] 33 to 35 respectively show the cases where the switch circuit 30 is in a first state, a second state, and a third state. In the first state shown in FIG. 33, the differential amplifier 50 x Each input terminal is connected to the comb tooth part PT x-2 ,PT x are connected, and these comb teeth PT x-2 ,PT x and the portion of the base portion PB that connects them together form one virtual loop coil. The same is true for the other differential amplifiers 50. Similarly, in the second state shown in FIG. x Each input terminal is connected to the comb tooth part PT x-1 ,PT x+1 are connected, and these comb teeth PT x-1 ,PT x+1 In the third state shown in FIG. 35, the differential amplifier 50 x Each input terminal is connected to the comb tooth part PT x ,PT x+2 are connected, and these comb teeth PT x ,PT x+2 and a portion of the base portion PB that connects them together form one virtual loop coil.

[0164] As can be seen from these, according to the A / B / C method, the virtual loop coil shifts in the x direction by a distance (second distance) shorter than the distance (first distance) between the two comb tooth portions PT that make up the virtual loop coil. The first distance is the distance between two adjacent comb tooth portions PT sandwiching one comb tooth portion PT, and the second distance is the distance between two adjacent comb tooth portions PT without sandwiching another comb tooth portion PT.

[0165] 36 is a plot of the maximum reception level of the pen signal PS obtained when the ODD / EVEN method is adopted and the maximum reception level of the pen signal PS obtained when the A / B / C method is adopted for each distance (pen height) from the touch surface 3a to the pen tip of the electromagnetic induction pen 2. From the results in this figure, it can be seen that with the A / B / C method, the reception level of the pen signal PS is greater than with the ODD / EVEN method at any pen height.

[0166] Fig. 32(b) is a diagram illustrating the distribution of the reception levels of the pen signal PS received when the tip of the electromagnetic induction pen 2 is at each position in the x direction for the position detection device 3 according to this embodiment (i.e., the position detection device 3 employing the A / B / C system). As is clear from a comparison with Fig. 32(a), when the A / B / C system is employed, the reception level of the pen signal PS is higher both near the folding line FL and at positions away from the folding line FL than when the ODD / EVEN system is employed. Therefore, it can be said that the position detection system 1 according to this embodiment realizes an improvement in the reception level of the pen signal PS near the folding line FL.

[0167] As described above, according to the position detection system 1 of this embodiment, the A / B / C method is adopted as a position detection method for the electromagnetic induction pen 2, in which the virtual loop coil is shifted by a distance shorter than the distance between the two comb tooth portions PT that constitute the virtual loop coil, so that it is possible to increase the reception strength of the pen signal PS in the vicinity of the folding line FL of the foldable display.

[0168] In the present embodiment, an example has been described in which the distance (first distance) between two comb-tooth portions PT constituting the virtual loop coil is the distance between two adjacent comb-tooth portions PT sandwiching one comb-tooth portion PT, and the shift distance (second distance) of the virtual loop coil is the distance between two adjacent comb-tooth portions PT without sandwiching another comb-tooth portion PT. However, as long as the condition that the second distance is shorter than the first distance is satisfied, the specific values ​​of the first distance and the second distance are not limited to the values ​​described in the present embodiment. For example, the first distance may be the distance between two adjacent comb-tooth portions PT sandwiching two comb-tooth portions PT, or the distance between two adjacent comb-tooth portions PT sandwiching three comb-tooth portions PT. In addition, the second distance may be the distance between two adjacent comb-tooth portions PT sandwiching one comb-tooth portion PT, or the distance between two adjacent comb-tooth portions PT sandwiching two comb-tooth portions PT.

[0169] 37 is a diagram for explaining a process performed by the sensor controller 31 according to a modification of the present embodiment. The sensor controller 31 according to this modification performs the process of switching the differential amplifier 50 when the switch circuit 30 is in the first state. x When the switch circuit 30 is in the second state, the differential amplifier 50 x When the switch circuit 30 is in the third state, the differential amplifier 50 x The added pen signal PS is obtained by adding the pen signal PS (hereinafter referred to as "pen signal PS3") output from SUM The other differential amplifiers 50 are configured to derive the position of the electromagnetic induction pen 2 using the above.

[0170] As described above, when the switch circuit 30 is in the first state, the comb tooth portion PT x-2 ,PT x A virtual loop coil is formed by the comb tooth portion PT and the portion of the base portion PB that connects them. The pen signal PS1 detected by this virtual loop coil is x-2 ,PT x-1The pen signal PS (hereinafter referred to as "pen signal PS") is detected by a virtual loop coil formed by the base PB and the portion of the base PB that connects them. x-2 , x-1 ") and the comb tooth part PT x-1 ,PT x The pen signal PS (hereinafter referred to as "pen signal PS") is detected by a virtual loop coil formed by the base PB and the portion of the base PB that connects them. x-1 , x The same is true when the switch circuit 30 is in the second or third state, and the pen signal PS2 is equal to or greater than the pen signal PS x-1 , x and comb tooth part PT x ,PT x+1 The pen signal PS (hereinafter referred to as "pen signal PS") is detected by a virtual loop coil formed by the base PB and the portion of the base PB that connects them. x , x+1 The pen signal PS3 is the sum of the pen signal PS x , x+1 and comb tooth part PT x+1 ,PT x+2 The pen signal PS (hereinafter referred to as "pen signal PS") is detected by a virtual loop coil formed by the base PB and the portion of the base PB that connects them. x+1 , x+2 Therefore, the sum pen signal PS1 to PS3 is obtained by adding the pen signals PS1 to PS3. SUM As shown in Figure 37, PS x-2 , x-1 +2 PS x-1 , x +2 PS x , x+1 +PS x+1 , x+2 This form is expressed as the additive pen signal PS SUM Therefore, according to the position detection system 1 of this modified example, like the position detection system 1 of the sixth embodiment, even if the electromagnetic induction pen 2 is tilted with respect to the touch surface 3a, the position can be detected with high accuracy.

[0171] 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. [Explanation of symbols]

[0172] 1 Position Detection System 2. Electromagnetic induction pen 3 Position detection device 3a Touch Surface 30 Switch Circuit 31 Sensor Controller 32 Host Processor 40,50 Differential Amplifier 50~55,60~62,S1,S2,T1,T2 Switch CCx Comb coil LCx,LCy loop coil LE linear electrode PB base PS Pen Signal PT comb tooth part T terminal pre Precharge signal sel Selection signal

Claims

1. an integrated circuit coupled to a receiving coil of an EMR sensor, the receiving coil has a plurality of ends along a first edge of the touch surface; the plurality of ends includes a first end and a second end; a differential amplifier having a first input terminal and a second input terminal; a group of switches that switch a connection destination of the first end between the second input terminal and any one of the second end, a ground terminal, and the first input terminal; [0023] An integrated circuit including

2. the receiving coil is composed of a plurality of loop coils including a first loop coil, the first end is the other end of the first loop coil, the switch group connects one end of the first loop coil to the first input terminal when the first end is connected to the second input terminal; 10. The integrated circuit of claim 1.

3. the receiving coil is composed of a plurality of loop coils including a first loop coil, the first end is the other end of the first loop coil, When the first end is to be connected to the ground end, the switch group connects one end of the first loop coil to the first input terminal and connects the second input terminal to the ground end.

10. The integrated circuit of claim 1.

4. the receiving coil is configured by a plurality of loop coils including a first loop coil and a second loop coil arranged adjacent to each other, the first end is the other end of the first loop coil, the second end is one end of the second loop coil, When the first end is connected to the second end, the switch group connects one end of the first loop coil to the first input terminal and connects the other end of the second loop coil to the second input terminal.

10. The integrated circuit of claim 1.

5. the receiving coil is a comb coil having a configuration in which a plurality of comb teeth are connected at one end to a base portion, the plurality of ends are other ends of the plurality of comb tooth portions, the group of switches switches between a first state in which the first end is connected to the second input terminal and a second state in which the first end is connected to the first input terminal in a time division manner; 10. The integrated circuit of claim 1.

6. a plurality of the differential amplifiers including a first differential amplifier and a second differential amplifier; the first state is a state in which the first end is connected to the second input terminal of the first differential amplifier and the second end is connected to the first input terminal of the second differential amplifier, the second state is a state in which the first end is connected to the first input terminal of the first differential amplifier and the second end is connected to the second input terminal of the first differential amplifier, 6. The integrated circuit of claim 5.

7. In the first state, a predetermined number of the ends including the first end are connected to the second input terminal of the first differential amplifier, and the predetermined number of the ends including the second end are connected to the first input terminal of the second differential amplifier, In the second state, the predetermined number of ends including the first end and the second end are connected to the second input terminal of the first differential amplifier, and the predetermined number of ends excluding the first end and the second end are connected to the first input terminal of the second differential amplifier.

7. The integrated circuit of claim 6.

8. an output terminal of the differential amplifier is connected to a sensor controller which detects the position of an electromagnetic induction pen based on a pen signal output from the differential amplifier; 6. An integrated circuit according to any one of claims 1 to 5.

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