Position detection device and electronic apparatus

Abstract

The purpose of the present invention is to improve the accuracy of position detection of an electromagnetic induction pen using an EMR sensor disposed so as to overlap a display device. This position detection device is provided with: an EMR sensor (15) disposed so as to overlap a display device; and a sensor controller (20) connected to the EMR sensor (15). The EMR sensor (15) includes a plurality of loop coils (LCx) arranged side by side in the X direction of the panel surface. The sensor controller (20) detects the position of the electromagnetic induction pen (2) on the basis of an alternating current (Rx2) generated using both a first alternating current output from a first loop coil (LCx) located in the vicinity of one end in the X direction among the plurality of loop coils (LCx) and a second alternating current output from a second loop coil (LCx) located in the vicinity of one end in the X direction among the plurality of loop coils (LCx). The second alternating current is output from a second loop coil (LCx) located on the opposite side of the first loop coil (LCx) across the center in the X direction of the panel surface.

Description

Technical Field

[0001] The present invention relates to a position detection device and an electronic device, and more particularly to a position detection device having a sensor arranged to overlap with a display device and an electronic device including such a position detection device. Background Art

[0002] In electronic devices that support pen input, such as smart phones and tablet terminals, there are electronic devices that are configured to detect the position of an electromagnetic induction pen by an EMR method, which is a type of electromagnetic induction method. In such electronic devices, display devices such as liquid crystal displays and organic EL displays and EMR sensors including multiple annular coils are arranged in an overlapping manner. Hereinafter, if the direction parallel to one side of the panel surface (touch surface) of the electronic device (for example, the lateral direction when observed from the user) is referred to as the X direction, and the direction orthogonal to the X direction (for example, the depth direction when observed from the user) is referred to as the Y direction, the multiple annular coils are configured to include multiple X-side annular coils extending in the Y direction and arranged in the X direction, and multiple Y-side annular coils extending in the X direction and arranged in the Y direction. An example of an electronic device with such a structure is disclosed in Patent Document 1.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2022-145907 Summary of the invention

[0006] Problems to be solved by the invention

[0007] The inventor of the present application actually produced an electronic device having a structure in which a display device and an EMR sensor are overlapped, and confirmed the characteristics of the EMR sensor. As a result, it was found that noise originating from the gate line of the display device was observed in the AC current output from the X-side loop coils located near the two ends of the panel surface among the multiple X-side loop coils. Such noise will cause the accuracy of the position detection of the electromagnetic induction pen to decrease, and therefore needs to be reduced.

[0008] Therefore, one of the objects of the present invention is to provide a position detection device and an electronic device capable of improving the accuracy of position detection by an electromagnetic induction pen using an EMR sensor arranged to overlap a display device.

[0009] Means for solving problems

[0010] The position detection device of the present invention includes: a sensor, which is arranged to overlap with a display device; and a sensor controller, which is connected to the sensor, wherein the sensor includes a plurality of annular coils arranged in a first direction on a panel surface, and the sensor controller detects the position of an electromagnetic induction pen based on a third alternating current generated by using both a first alternating current and a second alternating current, wherein the first alternating current is a current output from a first annular coil located near one end of the plurality of annular coils in the first direction, and the second alternating current is a current output from a second annular coil located on the opposite side of the first annular coil across the center of the panel surface in the first direction.

[0011] The electronic device of the present invention includes a display device and a position detection device, wherein the position detection device includes: a sensor, which is arranged to overlap with the display device; and a sensor controller, which is connected to the sensor, the sensor includes a plurality of annular coils arranged in a first direction on a panel surface, and the sensor controller detects the position of the electromagnetic induction pen based on a third alternating current generated by using both a first alternating current and a second alternating current, the first alternating current is a current output from a first annular coil located near one end of the first direction among the plurality of annular coils, and the second alternating current is a current output from a second annular coil located on the opposite side of the first annular coil across the center of the first direction of the panel surface.

[0012] Effects of the Invention

[0013] According to the present invention, it is possible to improve the accuracy of position detection of an electromagnetic induction pen using an EMR sensor arranged to overlap with a display device. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a diagram showing the structure of an electronic device 1 according to an embodiment of the present invention.

[0015] Figure 2 It is shown Figure 1 FIG. 2 is a diagram showing a detailed structure of the EMR sensor 15 and the sensor controller 20.

[0016] Figure 3 1 is a schematic diagram showing a state in which the display device 13 and the loop coil LCx in the EMR sensor 15 are partially arranged to overlap.

[0017] Figure 4 The toroidal coil X0 and the toroidal coil X 72 A diagram showing measurement results of noises originating from the gate lines GL respectively observed.

[0018] Figure 51 is a diagram showing simulation results of waveforms of alternating currents appearing at nodes n2 to n6 .

[0019] Figure 6 1 is a diagram showing a processing flow of a position detection process of the electromagnetic induction pen 2 executed by the control unit 21 of the sensor controller 20 according to the embodiment of the present invention.

[0020] Figure 7 1 is a diagram showing a processing flow of a position detection process of the electromagnetic induction pen 2 executed by the control unit 21 of the sensor controller 20 according to the embodiment of the present invention.

[0021] Figure 8 1 is a diagram showing a processing flow of a position detection process of the electromagnetic induction pen 2 executed by the control unit 21 of the sensor controller 20 according to the embodiment of the present invention.

[0022] Fig. 9 The diagram shows the observation result of the waveform of the AC current appearing in the sensor controller 20 according to the embodiment of the present invention and the result of performing FFT (Fast Fourier Transform) on the AC current.

[0023] Fig.10 1 is a diagram showing the observation result of the waveform of the AC current appearing in the sensor controller 20 according to the embodiment of the present invention. DETAILED DESCRIPTION

[0024] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0025] Figure 1 1 is a diagram showing the structure of an electronic device 1 according to an embodiment of the present invention. The figure also illustrates a resonant circuit included in an electromagnetic induction pen 2. The electronic device 1 is a computer that supports pen input to a display surface, and as shown in the figure, is configured to have a structure in which a cover glass 10, a touch sensor 11, an adhesive 12, a display device 13, a cover film 14, an EMR sensor 15, a magnetic sheet 16 are stacked in order from the panel surface 1a side, a sensor controller 20, and a host processor 30. In a typical example, the electronic device 1 is a smartphone or a tablet terminal.

[0026] The cover glass 10 is a member constituting the surface of the panel surface 1a. The touch sensor 11 is a sensor for detecting the position of the user's finger on the panel surface 1a, and in a typical example, is composed of an electrostatic capacitance type sensor including a plurality of transparent linear conductors. The adhesive 12 plays a role in fixing the touch sensor 11 to the surface of the display device 13.

[0027] The display device 13 is a device that displays an image according to an image signal supplied from the host processor 30, and is configured to have a plurality of pixels arranged in a matrix. In a typical example, the display device 13 is a liquid crystal display or an organic EL display. The cover film 14 serves to separate the EMR sensor 15 and the display device 13 and to bond them together.

[0028] The EMR sensor 15 is a sensor for detecting the position of the electromagnetic induction pen 2 on the panel surface 1a by the above-mentioned EMR method. Figure 2 The magnetic sheet 16 is a magnetic body formed on a flat plate, and plays a role of shielding the alternating magnetic field sent from the EMR sensor 15 .

[0029] The sensor controller 20 is an integrated circuit that constitutes a position detection device together with the touch sensor 11 and the EMR sensor 15. The sensor controller 20 performs processing to detect the position of the user's finger on the panel surface 1a using the touch sensor 11, and performs processing to detect the position of the electromagnetic induction pen 2 on the panel surface 1a using the EMR sensor 15. In addition, when the electromagnetic induction pen 2 has a function of sending data (a pen pressure value, on / off information of the side switch, pen ID, etc. described later), the sensor controller 20 also performs processing to receive data sent by the electromagnetic induction pen 2 using the EMR sensor 15. The sensor controller 20 is configured to sequentially supply the detected position and the received data to the host processor 30.

[0030] The host processor 30 is a central processing unit of the electronic device 1 that executes an operating system and various application programs of the electronic device 1 by executing a program read from a memory (not shown). The host processor 30 also has a function of supplying a video signal obtained as a result of executing the program to the display device 13.

[0031] The application program executed by the host processor 30 includes a drawing application program that draws based on the trajectory of the user's finger or the electromagnetic induction pen 2. The drawing application program is configured to be able to perform processing such as generating stroke data (data indicating the trajectory of the position) using the position and data supplied from the sensor controller 20, rendering and displaying the generated stroke data on the display device 13, generating and recording digital ink including the generated stroke data, and transmitting the generated digital ink to an external device.

[0032] The electromagnetic induction pen 2 is a pen-shaped device with a pen tip, such as Figure 1As shown, it is configured as a resonant circuit having a coil L and a capacitor C connected in series. When the resonant circuit enters the alternating magnetic field (described later) sent from the EMR sensor 15, an electromotive force is generated at both ends of the coil L, and the capacitor C is charged. Thereafter, if the sending of the alternating magnetic field from the EMR sensor 15 is interrupted, the alternating magnetic field as a reflection signal is sent from the coil L by the charge accumulated in the capacitor C. The sensor controller 20 is configured to detect the position of the electromagnetic induction pen 2 by detecting the alternating magnetic field.

[0033] Here, the capacitor C can be composed of a variable capacitance capacitor whose capacitance changes according to the pen pressure value indicating the pressure applied to the pen tip, the on / off state of the side switch provided on the surface, the pre-stored pen ID, etc. In this case, the capacitance of the capacitor C changes according to the pen pressure value and the on / off state of the switch, and as a result, the frequency of the alternating magnetic field sent from the coil L changes. The sensor controller 20 also performs processing to receive the data sent by the electromagnetic induction pen 2 by detecting the frequency change. The following description is continued on the premise that such data transmission and reception is performed between the electromagnetic induction pen 2 and the sensor controller 20.

[0034] Figure 2 2 is a diagram showing the detailed configuration of the EMR sensor 15 and the sensor controller 20. It should be noted that this diagram shows only the portion related to the EMR sensor 15 among the configurations of the sensor controller 20.

[0035] First, let's focus on the EMR sensor 15. The EMR sensor 15 is configured to include a plurality of loop coils LC. The plurality of loop coils LC include a plurality of loop coils LCx (X-side loop coils) extending in the Y direction and arranged in the X direction, and a plurality of loop coils LCy (Y-side loop coils) extending in the X direction and arranged in the Y direction. One end of each loop coil LC is grounded, and the other end is connected to the sensor controller 20.

[0036] like Figure 2 As shown, in this embodiment, the loop coil LCx is assumed to include loop coils X0 to X 72 The 73 toroidal coils and the toroidal coil LCx include toroidal coils Y0~Y 40 However, the numbers 73 and 41 are examples, and the number of loop coils LCx is not limited to 73, and the number of loop coils LCx is not limited to 41.

[0037] Next, the sensor controller 20 is focused on. The sensor controller 20 includes a control unit 21 , switch units 22 to 24 , an oscillating unit 25 , low-pass filters 26 and 27 , and an adding unit 28 .

[0038] The control unit 21 is a functional unit that controls the connection states of the switch units 22 to 24 to send out the alternating magnetic field from the panel surface 1a, detect the position of the electromagnetic induction pen 2 in the panel surface 1a, and receive the data sent out by the electromagnetic induction pen 2. The control unit 21 first sends out the alternating magnetic field from the panel surface 1a via the EMR sensor 15, and after stopping the sending, detects the alternating magnetic field sent out from the electromagnetic induction pen 2 as a reflection signal with respect to the alternating magnetic field via the EMR sensor 15, thereby detecting the position of the electromagnetic induction pen 2 and receiving the data sent out by the electromagnetic induction pen 2.

[0039] The control unit 21 detects the alternating magnetic field by detecting the alternating current (output current of the toroidal coil LC) that appears in the toroidal coil LC due to the alternating magnetic field. The control unit 21 has two input terminals for the alternating current, which are hereinafter referred to as nodes n1 and n2, respectively. In addition, the alternating current input to the node n1 is referred to as the alternating current Rx1, and the alternating current input to the node n2 is referred to as the alternating current Rx2.

[0040] The switch section 22 is a switch that connects any of the toroidal coils LC to the switch section 23 or the switch section 24 under the control of the control section 21. The switch section 23 is a single-pole three-throw switch having a common terminal connected to the switch section 22 and three selection terminals connected to the oscillating section 25, the node n1, and the low-pass filter 26, respectively, and plays a role of connecting any of the oscillating section 25, the node n1, and the low-pass filter 26 to the switch section 22 under the control of the control section 21. The switch section 24 is a single-pole single-throw switch provided between the switch section 22 and the low-pass filter 27, and plays a role of connecting or disconnecting the switch section 22 and the low-pass filter 27 under the control of the control section 21.

[0041] The oscillating unit 25 is a circuit including an oscillator that generates an alternating current Tx. The control unit 21 connects the oscillating unit 25 to any of the toroidal coils LC by controlling the switch units 22 and 23, thereby performing a process of sending out an alternating magnetic field from the panel surface 1a. More specifically, the alternating current Tx is supplied from the oscillating unit 25 to the toroidal coil LC connected to the oscillating unit 25 via the switch units 22 and 23. When the alternating current Tx is supplied in this way, an alternating magnetic field is generated around the toroidal coil LC. This alternating magnetic field becomes an alternating magnetic field sent out from the panel surface 1a.

[0042] The low-pass filter 26 is an RC filter including a resistor and a capacitor, and serves to remove the high-frequency component contained in the output current of the ring coil LC connected via the switch parts 22 and 23. Similarly, the low-pass filter 27 is also an RC filter including a resistor and a capacitor, and serves to remove the high-frequency component contained in the output current of the ring coil LC connected via the switch parts 22 and 24. The cutoff frequency of the low-pass filters 26 and 27 is set to a value (for example, 1 MHz) that is sufficiently higher than the frequency (for example, 660 kHz) of the alternating magnetic field sent by the electromagnetic induction pen 2. Hereinafter, the input end and the output end of the low-pass filter 26 are referred to as nodes n3 and n4, respectively, and the input end and the output end of the low-pass filter 27 are referred to as nodes n5 and n6, respectively.

[0043] The adding section 28 is a circuit for generating an alternating current Rx2 by adding the output current of the low-pass filter 26 and the output current of the low-pass filter 27. In a specific example, the adding section 28 is configured to include resistor elements 34 to 36, an operational amplifier 37, and an inverting buffer 38. The resistor element 34 is connected between the inverting input terminal of the operational amplifier 37 and the node n4. The resistor element 35 is connected between the inverting input terminal of the operational amplifier 37 and the node n6. The resistor element 36 is connected between the inverting input terminal and the output terminal of the operational amplifier 37. The non-inverting input terminal of the operational amplifier 37 is grounded, and the output terminal of the operational amplifier 37 is connected to the node n2 via the inverting buffer 38. The resistance values ​​of the resistor elements 34 to 36 are the same. According to the structure of the adding section 28, the alternating current Rx2 becomes a current obtained by adding the output current of the low-pass filter 26 and the output current of the low-pass filter 27.

[0044] The control unit 21 usually detects the position of the electromagnetic induction pen 2 and receives the data sent by the electromagnetic induction pen 2 based on the alternating current Rx1. On the other hand, once the position of the electromagnetic induction pen 2 is detected, the control unit 21 detects the position of the electromagnetic induction pen 2 and receives the data sent by the electromagnetic induction pen 2 based on the alternating current Rx2 for the predetermined number of loop coils LCx located at both ends of the panel surface 1a in the X direction. By performing such processing by the control unit 21, in the electronic device 1 of this embodiment, it is possible to reduce the noise from the gate line of the display device 13 superimposed on the output current of the loop coil LCx. This point will be described in detail below.

[0045] Figure 31 is a schematic diagram showing a situation where a portion of the annular coil LCx in the display device 13 and the EMR sensor 15 is overlapped. As shown in the figure, the display device 13 has gate lines GL extending in the Y direction at both ends in the X direction, and the annular coils LCx located near the two ends in the X direction among the multiple annular coils LCx extend in an overlapping manner with the gate lines GL. Extending in an overlapping manner with the gate lines GL means that the signal flowing in the gate lines GL overlaps with the annular coils LCx. In fact, a drive signal (a signal for controlling the on and off of the transistors configured in the pixels) is supplied from the host processor 30 to the gate lines GL, and the drive signal overlaps with the output current of the annular coils LCx located near the two ends in the X direction as noise. Such noise will become a cause of the decrease in the accuracy of the position detection of the electromagnetic induction pen 2 and the data reception from the electromagnetic induction pen 2 by the control unit 21, and therefore needs to be reduced. It should be noted that the frequency band of the drive signal overlaps with the frequency band of the alternating magnetic field sent by the electromagnetic induction pen 2, so it is difficult to remove the noise using only a filter.

[0046] Here, Figure 4 The output current of the loop coil X0 and the output current of the loop coil X0 are shown. 72 A graph is shown showing the measurement results of the noise of the output current originating from the gate line GL. The horizontal axis of the graph is time, and the vertical axis is amplitude. As can be understood from the graph, the drive signals applied to the two gate lines GL located at the two ends in the X direction are approximately anti-phase signals to each other. Therefore, if the output current (first alternating current) of the annular coil LCx (hereinafter referred to as the "first annular coil LCx") located near one end in the X direction and the output current (second alternating current) of the annular coil LCx (hereinafter referred to as the "second annular coil LCx") located on the opposite side of the first annular coil LCx across the center of the X direction of the panel surface 1a are added, the noise originating from the gate line GL can be eliminated.

[0047] Therefore, the control unit 21 of this embodiment detects the output current of the first loop coil LCx by appropriately controlling Figure 2 The switch units 22 to 24 shown in the figure are used to connect the first loop coil LCx to the low-pass filter 26 and the second loop coil LCx to the low-pass filter 27. And, as a result, the AC current Rx2 (third AC current) input to the node n2 is obtained as the output current of the first loop coil LCx. By doing so, the noise from the gate line GL superimposed on the output current of the first loop coil LCx is eliminated by the noise from the gate line GL superimposed on the output current of the second loop coil LCx in the adding unit 28, so that the noise from the gate line GL is reduced in the AC current Rx2. The same is true when the output current of the second loop coil LCx is detected.

[0048] Figure 4 The noise waveforms shown in the figure (overlapping the output current of the toroidal coil X0 and the output current of the toroidal coil X1 and the output current of the toroidal coil X2, respectively) are also shown. 72 The measurement result of the AC current Rx2 corresponding to the waveform of the noise of the output current from the gate line GL of the loop coil LCx is shown in FIG. 1 . As can be understood from the result of this figure, the processing performed by the control unit 21 of this embodiment can reduce the noise from the gate line GL superimposed on the output current of the loop coil LCx. In the example of this figure, the amplitude of the noise from the gate line GL is reduced to about half.

[0049] It should be noted that if Figure 4 As illustrated, sometimes, a driving signal applied to one of the two gate lines GL located at both ends in the X direction has a slight delay Δ (for example, a delay of 2 μs) relative to the inverted signal of the driving signal applied to the other of the two gate lines GL located at both ends in the X direction. Figure 2 The low-pass filters 26 and 27 shown are provided to absorb the delay Δ, and the waveform of the noise becomes smooth after passing through the low-pass filters 26 and 27. Therefore, in the sensor controller 20 of this embodiment, even if there is a delay Δ, the noise originating from the gate line GL that overlaps with the output current of the annular coil LCx can be reduced.

[0050] Figure 5 1 is a diagram showing the simulation results of the waveforms of the alternating currents appearing at the nodes n2 to n6. 72 In the state where there is no electromagnetic induction pen 2 near 72 This is an example of a case where the loop coil X0 is connected to the node n3 and the loop coil X0 is connected to the node n5. Figure 5 (a) to (e) show the waveforms of the AC current noise appearing at nodes n3, n5, n4, n6, and n2, respectively. The horizontal axis of each figure is time, and the vertical axis is amplitude. Figure 5 As can be seen from the simulation results shown, the noise originating from the gate line GL and superimposed on the output current of the loop coil LCx is reduced by the processing of the low-pass filters 26 and 27 and the adding section 28 .

[0051] Figure 6~Figure 8 The diagrams show the processing flow of the position detection processing of the electromagnetic induction pen 2 executed by the control unit 21 of the sensor controller 20 of this embodiment. Hereinafter, the processing for reducing the noise from the gate line GL superimposed on the output current of the loop coil LCx will be described in more detail with reference to these diagrams.

[0052] First refer to Figure 6 , the control unit 21 first performs a process for newly detecting the position of the electromagnetic induction pen 2 whose position has not been detected yet, that is, a global scan (step S1).

[0053] Figure 7 Shown in Figure 6 As shown in the figure, the control unit 21 first performs the processing of steps S11 and S12 on each of the plurality of loop coils LCy (step S10). Step S11 is a process of applying an alternating current Tx to the loop coil LCy of interest by appropriately controlling the switch units 22 and 23. Step S12 is a process of switching the switch unit 23 to the node n1 side and detecting the alternating current Rx1 input to the node n1 as the output current of the loop coil LCy of interest.

[0054] Next, the control unit 21 performs the processing of steps S14 and S15 on each of the plurality of loop coils LCx (step S13). The processing of steps S14 and S15 is the same as the processing of steps S11 and S12 except that the focus loop coil LCy is changed to the focus loop coil LCx.

[0055] The control unit 21 that has completed the processing of steps S10 to S15 detects the position of the electromagnetic induction pen 2 based on the detection results of the output currents of each loop coil LCx and LCy, and receives the data sent by the electromagnetic induction pen 2 (step S16). Specifically, the control unit 21 detects the Y coordinate of the position of the electromagnetic induction pen 2 based on the amplitude of the alternating current Rx1 detected by each loop coil LCy, and detects the X coordinate of the position of the electromagnetic induction pen 2 based on the amplitude of the alternating current Rx1 detected by each loop coil LCx. In addition, the control unit 21 detects the frequency of the alternating current Rx1 detected at the loop coil LCy or the loop coil LCx closest to the detected position among the multiple loop coils LCy or the multiple loop coils LCx, and obtains the data sent by the electromagnetic induction pen 2 based on the result.

[0056] return Figure 6 , the control unit 21 that has completed the processing of step S1 determines whether the position of the electromagnetic induction pen 2 is detected in step S1 (step S2). As a result, if it is determined that it is not detected, the control unit 21 returns to step S1 and performs global scanning again. On the other hand, if it is determined that it is detected, the control unit 21 stores the detected position (step S3), and outputs the detected position and the received data to the host processor 30 (step S4). Then, the control unit 21 performs processing for updating the position of the electromagnetic induction pen 2 whose position has been stored, that is, local scanning (step S5).

[0057] Figure 8 Shown in Figure 6As shown in the figure, the control unit 21 first performs the processing of steps S21 and S22 for a predetermined number (for example, 3 or 4) of loop coils LCy located near the stored position (step S20). The processing of steps S21 and S22 is similar to that of steps S21 and S22. Figure 7 The processes in steps S11 and S12 shown are the same.

[0058] Next, the control unit 21 performs the processing of steps S24 to S29 for a predetermined number (for example, 3 or 4) of loop coils LCx located near the stored positions (step S23). Specifically, the control unit 21 first determines whether the loop coil LCx of interest is the loop coil LCx located near both ends in the X direction (step S24). Specifically, a table is pre-stored to store whether each loop coil LCx is located near both ends in the X direction, and the determination of step S24 can be performed by referring to the table.

[0059] If the result of the determination in step S24 is that the loop coil LCx is not located near the two ends in the X direction, the control unit 21 applies the AC current Tx to the loop coil LCx of interest by appropriately controlling the switch units 22 and 23 (step S28), and then switches the switch unit 23 to the node n1 side and detects the AC current Rx1 input to the node n1 as the output current of the loop coil LCx of interest (step S29). The processing of steps S28 and S29 is similar to that of Figure 7 The processes in steps S14 and S15 shown are the same processes.

[0060] On the other hand, as a result of the determination in step S24, the control unit 21 determines that it is located near both ends in the X direction and applies the AC current Tx to the loop coil LCx of interest by appropriately controlling the switch units 22 and 23 (step S25), and then connects the loop coil LCx of interest to the low-pass filter 26 and connects the loop coil LCx located on the opposite side of the loop coil LCx of interest across the center in the X direction to the low-pass filter 27 by appropriately controlling the switch units 22 to 24 (step S26). Then, the AC current Rx2 input to the node n2 is detected as the output current of the loop coil LCx of interest (step S27).

[0061] After completing the processing of steps S20 to S29, the control unit 21 detects the position of the electromagnetic induction pen 2 based on the detection results of the output currents of the loop coils LCx and LCy, and receives the data sent by the electromagnetic induction pen 2 (step S30). This processing is similar to the above except that the number of loop coils LCx and LCy to be processed is reduced. Figure 7 The processing of step S16 shown is the same as that of step S16.

[0062] return Figure 6 , the control unit 21 that has completed the processing of step S5 determines whether the position of the electromagnetic induction pen 2 is detected in step S5 (step S6). As a result, if it is determined that it is not detected, the control unit 21 resets the stored position (step S9), and then returns to step S1 to perform a global scan. On the other hand, if it is determined that it is detected, the control unit 21 updates the stored position using the detected position (step S7), and outputs the detected position and the received data to the host processor 30 (step S8). Then, the control unit 21 returns to step S5 and performs a local scan again.

[0063] As described above, according to the electronic device 1 of this embodiment, when detecting the output current of the loop coil LCx near both ends in the X direction where the noise originating from the gate line GL overlaps, the output current of the loop coil LCx is added to the output current of the loop coil LCx, which is located on the opposite side of the loop coil LCx across the center in the X direction of the panel surface 1a, thereby reducing the noise originating from the gate line GL of the display device 13 that overlaps the output current of the loop coil LCx. Therefore, according to the electronic device 1 of this embodiment, the accuracy of position detection of the electromagnetic induction pen 2 using the EMR sensor 15 arranged to overlap the display device 13 can be improved. In addition, the accuracy of receiving data sent by the electromagnetic induction pen 2 can also be improved.

[0064] In addition, according to the electronic device 1 of this embodiment, since low-pass filters 26 and 27 are provided in the front section of the adding section 28, even if the timing of the driving signal is slightly deviated between the two gate lines GL located at the two ends of the X direction, the noise originating from the gate lines GL that overlaps with the output current of the annular coil LCx can be reduced.

[0065] Fig. 9 1 is a diagram showing the observation result of the waveform of the alternating current appearing in the sensor controller 20 of the present embodiment and the result of performing FFT (Fast Fourier Transform) on the alternating current. 72 In the state where the electromagnetic induction pen 2 exists near the loop coil X0, the loop coil X0 is connected to the node n5 and the loop coil X 72 This is an example of a case where the node is connected to the node n3.

[0066] Fig. 9 (a) and (c) show the ring coils X0 and X 72 The output current, Fig. 9 (b) and (d) show the ring coils X0 and X 72 The FFT result of the output current. In addition, Fig. 9 (e) shows the AC current Rx2, Fig. 9 (f) shows the FFT result of the AC current Rx2. Fig. 9 The horizontal axis of (a)(c)(e) is time, and the vertical axis is amplitude. Fig. 9 In (b), (d), and (f), the horizontal axis is frequency and the vertical axis is amplitude.

[0067] Fig. 9 P shown in (d) is the frequency of the alternating magnetic field sent from the electromagnetic induction pen 2. In a typical example, P = 660kHz. Fig. 9 As shown in (b) and (d), in the toroidal coil X 72 In the output current of the loop coil X0, a large peak is observed at the frequency P. On the other hand, in the output current of the loop coil X0, no such peak is observed. This reflects that in the loop coil X 72 There is an electromagnetic induction pen 2 near the loop coil X0, while there is no electromagnetic induction pen 2 near the loop coil X0. Fig. 9 (c) but not in Fig. 9 The sinusoidal waveform of (a) corresponds to the waveform of frequency P.

[0068] If you observe Fig. 9 (b)(d), then the ring coils X0, X 72 The output current of has multiple peaks in a wide frequency band including the frequency P. These multiple peaks are generated by the drive signal flowing in the gate line GL and are noises to the sensor controller 20. Fig. 9 In the AC current Rx2 shown in (f), the peak of the frequency P remains, but the peaks other than that are greatly suppressed. Fig. 9 The waveform of (e) can also be understood, Fig. 9 The noise is suppressed in the waveform (c), and the sine wave of the frequency P appears more clearly. Therefore, it can be said that the electronic device 1 of the present embodiment achieves reduction of the noise from the gate line GL superimposed on the output current of the loop coil LCx.

[0069] Fig.10 1 is a diagram showing the observation result of the waveform of the AC current appearing in the sensor controller 20 of the present embodiment. Fig.10 (a)(b)(c) shows the toroidal coil X 71 In the state where the electromagnetic induction pen 2 exists near the loop coil X1, the loop coil X1 is connected to the node n5 and the loop coil X 71 For example, when connecting to node n3, Fig.10 (d) (e) (f) shows the toroidal coil X 70 In the state where the electromagnetic induction pen 2 exists near the loop coil X2, the loop coil X2 is connected to the node n5 and the loop coil X70 For example, when connecting to node n3, Fig.10 (g)(h)(i) shows the toroidal coil X 69 In the state where the electromagnetic induction pen 2 exists near the loop coil X3, the loop coil X3 is connected to the node n5 and the loop coil X 69 This is an example of a case where the node is connected to the node n3. The horizontal axis of each graph is time, and the vertical axis is amplitude.

[0070] observe Fig.10 As can be understood from (a), (d), and (g), the noise decreases in the order of the toroidal coil X1, the toroidal coil X2, and the toroidal coil X3. Fig.10 The toroidal coil X shown in (b)(e)(h) 71 、Toroidal coil X 70 、Toroidal coil X 69 This is also caused by being far away from the gate line GL. Fig.10 In (c), (f), and (i), in the alternating current Rx2, the component of the frequency P remains, and the frequency components other than the frequency P are greatly suppressed. Therefore, it can be said that in the electronic device 1 of this embodiment, not only the toroidal coils X0 and X1 located at the end 72 , in the ring coils adjacent to them, the noise originating from the gate line GL is also reduced.

[0071] As mentioned above, although the preferred embodiment of the present invention has been described, the present invention is not limited to such embodiment at all, and the present invention can be implemented in various forms within the scope not departing from the gist of the present invention.

[0072] For example, in the above embodiment, an example is described in which the AC current Rx2 is used only in local scanning to perform position detection, and the AC current Rx1 is used in global scanning to perform position detection, but it is also possible to use the AC current Rx2 in global scanning to perform position detection, etc. However, in global scanning, noise is unlikely to be a problem, so the AC current Rx2 can be used only in local scanning to perform position detection, etc. as in this embodiment.

[0073] In addition, in the above-mentioned embodiment, an example of adding the output current of the first circular coil LCx and the output current of the second circular coil LCx is described, but in the case where the winding directions of the circular coil LCx at both ends in the X direction are opposite, the output current of the second circular coil LCx can also be subtracted from the output current of the first circular coil LCx.

[0074] In addition, according to the processing described in the above embodiment, when the AC current Rx2 is used for position detection, the two loop coils LCx are connected in parallel from the perspective of the control unit 21, but the inductance is 1 / 2 compared to the case where the AC current Rx1 is used for position detection. Therefore, the control unit 21 may also perform processing to double the amplitude of the detected AC current Rx2. This processing is preferably performed in the digital area using the firmware of the sensor controller 20.

[0075] Description of Reference Numerals

[0076] 1 Electronic equipment

[0077] 1a Panel surface

[0078] 2 Electromagnetic induction pen

[0079] 10 Cover glass

[0080] 11 Touch Sensor

[0081] 12 Adhesive

[0082] 13 Display device

[0083] 14 Covering film

[0084] 15 EMR Sensor

[0085] 15 Covering film

[0086] 16 Magnetic sheet

[0087] 20 Sensor Controller

[0088] 21 Control Department

[0089] 22~24 Switch part

[0090] 25 Oscillation unit

[0091] 26, 27 Low-pass filter

[0092] 28 Addition

[0093] 30 Host processor

[0094] 34~36 Resistor element

[0095] 37 Operational Amplifier

[0096] 38 Inverting Buffer

[0097] C Capacitor

[0098] GL Gate Line

[0099] L Coil

[0100] LC, LCx, LCy Toroidal coils.

Claims

1. A position detection device, comprising: The sensor is configured to overlap with the display device; as well as a sensor controller connected to the sensor, The sensor includes a plurality of annular coils arranged in a first direction on the panel surface. The sensor controller detects the position of the electromagnetic induction pen based on a third alternating current generated by using both a first alternating current and a second alternating current, wherein the first alternating current is a current output from a first annular coil located near one end of the plurality of annular coils in the first direction, and the second alternating current is a current output from a second annular coil located on the opposite side of the first annular coil at the center of the first direction across the panel surface.

2. The position detection device according to claim 1, wherein: The sensor controller generates the third alternating current by adding the first alternating current and the second alternating current.

3. The position detection device according to claim 1, wherein: The sensor controller includes a first low-pass filter and a second low-pass filter, The sensor controller generates the third alternating current by adding the first alternating current that has passed through the first low-pass filter and the second alternating current that has passed through the second low-pass filter.

4. The position detection device according to claim 3, wherein: The cutoff frequency of each of the first low-pass filter and the second low-pass filter is set to a frequency higher than a frequency of the alternating magnetic field sent from the electromagnetic induction pen.

5. The position detection device according to claim 1, wherein: The sensor controller detects the position of the electromagnetic induction pen based on the third alternating current when the position of the electromagnetic induction pen has been detected, and detects the position of the electromagnetic induction pen based on the first alternating current when the position of the electromagnetic induction pen has not been detected.

6. An electronic device comprising a display device and a position detection device, wherein: The position detection device comprises: a sensor, arranged to overlap with the display device; and a sensor controller connected to the sensor, The sensor includes a plurality of annular coils arranged in a first direction on a panel surface. The sensor controller detects the position of the electromagnetic induction pen based on a third alternating current generated by using both a first alternating current and a second alternating current, wherein the first alternating current is a current output from a first annular coil located near one end of the plurality of annular coils in the first direction, and the second alternating current is a current output from a second annular coil located on the opposite side of the first annular coil at the center of the first direction across the panel surface.

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