Pointing position detection device and pointing position detection method

Abstract

Provided are an indication position detection device and indication position detection method that can suppress deteriorations in the detection accuracy of an indication position indicated by an indicator. The indication position detection device, which detects an indication position indicated by an indicator, comprises a first transmission unit and a second transmission unit. The first transmission unit transmits a first transmission signal related to first processing for detecting the indication position indicated by the indicator. The second transmission unit transmits a second transmission signal related to second processing different from the first processing. In the same period, the waveform of the first transmission signal and the waveform of the second transmission signal are orthogonal to each other.

Description

[Technical field]

[0001] The present invention relates to a pointed position detection device and a pointed position detection method. [Background technology]

[0002] In electronic devices such as tablet-type information terminals equipped with flat displays (e.g., liquid crystal panels), pointed position detection devices that detect a position (pointed position) pointed to by a pointing object such as a finger or a pen are mounted and widely used. Various position detection methods are provided for use in pointed position detection devices, such as a resistive film method, an electromagnetic induction method, and a capacitance method.

[0003] Of these, an electromagnetic induction type pointing position detection device, as disclosed in Patent Document 1, for example, is composed of a position detection device equipped with a sensor having a number of loop coils arranged in the X-axis and Y-axis directions of the coordinate axes, and an electronic pen as a pen-shaped position indicator having a resonant circuit consisting of a coil and a capacitor as an example of an inductance element wound around a magnetic core.

[0004] The position detection device supplies a transmission signal of a predetermined frequency to the loop coil of the sensor to transmit a magnetic field to the electronic pen. The resonant circuit of the electronic pen is configured to have a resonant frequency corresponding to the frequency of the transmission signal, and stores magnetic energy based on electromagnetic induction between the electronic pen and the loop coil of the sensor. The electronic pen then feeds back the magnetic field based on the magnetic energy stored in the resonant circuit to the loop coil of the sensor of the position detection device.

[0005] The magnetic field from the electronic pen generates an induced voltage in the loop coil of the sensor, and the position detection device detects the coordinate values ​​in the X-axis and Y-axis directions of the position on the sensor indicated by the electronic pen based on the value of the induced voltage generated in each loop coil.

[0006] Electromagnetic induction type pointing position detection devices are widely used because they can input a pointing position with relatively high precision using an electronic pen as a pointing body.

[0007] Furthermore, there are two types of capacitive position detection devices, which are used to detect the position pointed to by a pointer (such as a finger or a pen-shaped position pointer (electrostatic pen)) used on touch panels, etc.: a surface capacitive type and a projected capacitive type, and both types detect the position pointed to by the pointer by detecting a change in the electrostatic coupling state between a sensor electrode and the pointer. Pointing position detection devices using a type called a cross-point electrostatic coupling type, which is an extension of the projected capacitive type, are also in widespread use (see, for example, Patent Document 2).

[0008] Fig. 9 shows an example of the configuration of a sensor of a cross-point capacitance type pointing position detection device. As shown in Fig. 9, the sensor of this cross-point capacitance type pointing position detection device is configured by arranging a plurality of upper electrodes Ex in the Y-axis direction (vertical direction) and lower electrodes Ey in the X-axis direction (horizontal direction) of the pointing input surface at predetermined intervals in the X-axis direction and Y-axis direction, respectively, so that they are perpendicular to each other and arranged with a small gap between them. In this case, a predetermined capacitance Co (fixed capacitance) is formed at the overlapping portion (cross point) between the upper electrodes Ex and the lower electrodes Ey.

[0009] When a pointer 100, such as a position indicator held by a user or a user's finger, approaches or comes into contact with the pointing input surface, a capacitance Cf is formed between the electrodes Ex, Ey at that position and the pointer. The pointer 100 is connected to the ground through the human body via a predetermined capacitance Cg. As a result, due to the capacitances Cf and Cg, the capacitance between the upper electrode Ex and the lower electrode Ey changes at the position pointed to by the pointer 100. In a position detection device using the cross-point capacitance method, the change in capacitance is detected to identify the position pointed to by the pointer 100 within the pointing input surface.

[0010] This change in capacitance is detected by the position detection circuit 101. For example, the position detection circuit 101 detects the change in capacitance between the upper electrode Ex and the lower electrode Ey by supplying a predetermined transmission signal to the lower electrode Ey as a transmission electrode and receiving a reception signal from the upper electrode Ex as a reception electrode and detecting a current change in the reception signal. The position detection circuit 101 detects the position indicated by the indicator by simultaneously supplying a transmission signal to all of the transmission electrodes and simultaneously performing a process of detecting a current change in the reception signal from all of the reception electrodes.

[0011] The pointing object for which the above-mentioned electromagnetic induction type pointing position detection sensor detects the pointing position is an electromagnetic induction type electronic pen, while the pointing object for which the capacitive type pointing position detection sensor detects the pointing position is a finger or an electrostatic pen, and the objects to be detected are completely different. Therefore, it is conceivable to mount a pointing position detection sensor of the electromagnetic induction type and a pointing position detection sensor of the capacitive type in one pointing position detection device. With this pointing position detection device, for example, while detecting a pointing position indicated by a finger using the capacitive type pointing position detection sensor, it is possible to simultaneously detect a pointing position indicated by an electronic pen using the electromagnetic induction type pointing position detection sensor. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] JP 2009-86925 A [Patent Document 2] JP 2011-3035 A Summary of the Invention [Problem to be solved by the invention]

[0013] Incidentally, in electronic devices such as tablet-type information terminals equipped with a display (for example, a liquid crystal panel), in order to realize miniaturization of the electronic device while maintaining the size of the display panel, it is an issue to deal with narrowing the width of the frame (picture frame) surrounding the display panel. In order to deal with narrowing the picture frame, it is required to reduce the arrangement space of the loop coil and signal line used in the indication position detection device in the electronic device.

[0014] However, when an electromagnetic induction type pointing position detection device and a capacitive type pointing position detection device are mounted on one electronic device, the loop coil used in the electromagnetic induction type pointing position detection device and the signal line used in the capacitive type pointing position detection device for transmitting a transmission signal and receiving a reception signal may be disposed close to each other. In this case, the loop coil and the signal line may be magnetically coupled (interfered with each other), causing electromagnetic noise to be mixed into the loop coil from the signal line used for transmitting the transmission signal, or electromagnetic noise to be mixed into the signal line used for receiving the reception signal from the loop coil. When electromagnetic noise is mixed into the loop coil from the signal line used for transmitting the transmission signal, the S / N ratio of the magnetic field transmitted from the electronic pen and received by the loop coil decreases, and the detection accuracy of the pointing position in the electromagnetic induction type pointing position detection device decreases. Also, when electromagnetic noise is mixed into the signal line used for receiving the reception signal from the loop coil, the S / N ratio of the reception signal decreases, and the detection accuracy of the pointing position in the capacitive type pointing position detection device decreases.

[0015] Furthermore, when an electromagnetic induction type pointing position detection device and a capacitive type pointing position detection device are mounted on one electronic device, the loop coil used in the electromagnetic induction type pointing position detection device, the signal line used in the capacitive type pointing position detection device, and the signal line (e.g., clock line) used to transmit a drive signal (e.g., clock signal) that drives a display panel may be arranged close to each other. In this case, electromagnetic noise may be mixed from the signal line used to transmit the drive signal into the loop coil used in the electromagnetic induction type pointing position detection device and the signal line used to receive a reception signal in the capacitive type pointing position detection device, resulting in a decrease in the S / N ratio of the magnetic field transmitted from the electronic pen and received by the loop coil, thereby decreasing the accuracy of position detection in the electromagnetic induction type pointing position detection device, or a decrease in the S / N ratio of the received signal, thereby decreasing the accuracy of position detection in the capacitive type pointing position detection device.

[0016] An object of the present invention is to provide a pointed position detection device and a pointed position detection method that are capable of suppressing a decrease in the detection accuracy of a position pointed to by a pointer. [Means for solving the problem]

[0017] According to the present invention, there is provided an indication position detection device having the following configuration. [1] An indication position detection device for detecting a position indicated by an indicator, comprising a first transmission unit and a second transmission unit, wherein the first transmission unit transmits a first transmission signal associated with a first process for detecting a position indicated by an indicator, and the second transmission unit transmits a second transmission signal associated with a second process different from the first process, and wherein the waveform of the first transmission signal and the waveform of the second transmission signal are orthogonal during the same period.

[0018] According to the present invention, the waveforms of the first transmission signal and the second transmission signal are orthogonal during the same period, and noise mixed into the received signal related to the first or second processing by the first or second transmission signal is suppressed, thereby suppressing deterioration in the position detection accuracy of the first or second processing related to the received signal.

[0019] Various embodiments of the present invention will be described below. The embodiments described below can be combined with each other. [2] An indication position detection device as described in [1], wherein a value obtained by subtracting the wave number of the second transmission signal from the wave number of the first transmission signal during the same period is a positive or negative integer. [3] An indication position detection device as described in [1] or [2], wherein the first process is a process of detecting a position indicated by an indicator using an electromagnetic induction method, and the second process is a process of detecting a position indicated by an indicator using a capacitance method. [4] The pointing position detection device according to any one of [1] to [3], wherein a transmission period of the first transmission signal overlaps with at least a portion of a transmission period of the second transmission signal. [5] An indication position detection device as described in [4], wherein the start and end points of the transmission period of the first transmission signal are the same as the start and end points of the transmission period of the second transmission signal. [6] An indication position detection device as described in [1], further comprising a display, wherein the first process is a process of detecting an indication position on the display by an indicator using an electromagnetic induction method, and the second process is a process of driving the display. [7] [1] An indication position detection device as described above, further comprising a display, wherein the first process is a process of detecting an indication position on the display by an indicator using a capacitive method, and the second process is a process of driving the display. [8] An indication position detection device that detects a position indicated by an indicator, comprising a first transmitting unit, a second transmitting unit, a first receiving unit, and a second receiving unit, wherein the first transmitting unit transmits a first transmission signal related to a first process of detecting a position indicated by the indicator, the second transmitting unit transmits a second transmission signal related to a second process of detecting a position indicated by the indicator, the first receiving unit receives a first reception signal related to the first process, and the second receiving unit receives a second reception signal related to the second process, wherein the waveform of the first reception signal and the waveform of the second reception signal are orthogonal during the same period. [9] [8] An indication position detection device as described in [8], wherein a value obtained by subtracting the wave number of the second transmission signal from the wave number of the first transmission signal during the same period is a positive or negative integer.

[10] An indication position detection device as described in [8] or [9], wherein the first receiving unit receives the first reception signal during a transmission period of the second transmission signal.

[11] The pointing position detection device according to any one of [8] to

[10] , wherein the second receiving unit receives the second reception signal during a transmission period of the first transmission signal.

[12] An indication position detection device as described in any one of [8] to

[11] , wherein a guard interval is provided between a reception period of the first reception signal and a reception period of the second reception signal.

[13] A method for detecting a position indicated by an indicator, comprising the steps of transmitting a first transmission signal associated with a first process for detecting a position indicated by an indicator, and transmitting a second transmission signal associated with a second process different from the first process, wherein the waveform of the first transmission signal and the waveform of the second transmission signal are orthogonal to each other during the same period.

[14] A method for detecting a position indicated by an indicator, comprising the steps of: transmitting a first transmission signal associated with a first process for detecting a position indicated by the indicator; transmitting a second transmission signal associated with a second process for detecting a position indicated by the indicator; receiving a first reception signal associated with the first process; and receiving a second reception signal associated with the second process, wherein the waveform of the first reception signal and the waveform of the second reception signal are orthogonal during the same period. Effect of the Invention

[0020] According to the present invention, it is possible to suppress a decrease in the detection accuracy of a position pointed to by a pointer. [Brief description of the drawings]

[0021] [Figure 1] 1 is an exploded perspective view showing a configuration example of an electronic device according to an embodiment of the present invention. [Diagram 2] 3 is a diagram illustrating an example of the configuration of a first sensor and a position detection circuit according to the present embodiment. FIG. [Diagram 3] 4 is a diagram illustrating an example of the configuration of a second sensor and a position detection circuit in the present embodiment. FIG. [Figure 4] FIG. 4 is a diagram illustrating an example of a control configuration of a display device according to the present embodiment. [Diagram 5] FIG. 1 is a diagram for explaining a problem to be solved in the present embodiment. [Figure 6] FIG. 1 is a diagram for explaining a problem to be solved in the present embodiment. [Figure 7] 11A to 11C are waveform diagrams relating to a process for detecting a position pointed to by a pointer. [Figure 8] 11A to 11C are waveform diagrams relating to a process for detecting a position pointed to by a pointer. [Figure 9] FIG. 1 is a diagram illustrating an example of a configuration of a sensor of a cross-point capacitive pointing position detection device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the accompanying drawings, in which the same reference numerals denote the same or similar configurations.

[0023] (Overall configuration) 1 is an exploded view showing a configuration example of an electronic device 10 (corresponding to the "pointed position detection device" of the present invention) in this embodiment. The electronic device 10 is a pad-type terminal that has a function of detecting a position pointed to by an electromagnetic induction type pointing body (hereinafter referred to as a "first pointing body") consisting of a position indicator such as an electronic pen, using a sensor (hereinafter referred to as a "first sensor") for detecting a pointed position of the electromagnetic induction type, and also has a function of detecting a position pointed to by a pointing body (hereinafter referred to as a "second pointing body") such as a finger or a position indicator (electrostatic pen) on a display screen of a display device, using a sensor (hereinafter referred to as a "second sensor") for detecting a pointed position of the capacitance type, and can simultaneously detect positions pointed to by the first and second pointing bodies using both sensors.

[0024] The electronic device 10, which is an example of a pad-type terminal, is composed of a first sensor 20 for detecting an indicated position using an electromagnetic induction method, a display device 30, a second sensor 40 for detecting a position using a capacitance method, a control circuit board 50, a planar member 60, and a housing 70.

[0025] The display device 30 is made of a flat display such as a liquid crystal display or an organic EL display, and is provided with a display screen 33 on which a large number of display pixels 32 are arranged in the X-axis direction (horizontal direction) on a display substrate 31, and a large number of display pixels 32 are arranged in the Y-axis direction (vertical direction) perpendicular to the X-axis direction.

[0026] The first sensor 20 is disposed on the rear side of the display screen 33 of the display device 30 so as to overlap with the display device 30. The second sensor 40 is disposed on the front side of the display screen 33 of the display device 30 so as to overlap with the display screen 33 of the display device 30. Therefore, the first sensor 20 and the second sensor 40 are also disposed in an overlapping relationship.

[0027] The detection area of ​​the first sensor 20, which is capable of detecting the position indicated by the first indicator, the detection area of ​​the second sensor 40, which is capable of detecting the position indicated by the second indicator, and the display area of ​​the display screen 33 of the display device 30 are approximately equal in size and are arranged in an overlapping relationship.

[0028] Although not shown in FIG. 1, an electromagnetic induction type position detection circuit is connected to the first sensor 20, and a capacitance type position detection circuit is connected to the second sensor 40. The first and second position detection circuits are provided on a control circuit board 50, and are connected to the first sensor 20 and the second sensor 40 by, for example, a flexible cable. The control circuit board 50 is equipped with a microcomputer for controlling the electronic device 10, a control circuit for the display device 30, other electronic components, and a copper foil wiring pattern. Note that the electronic device 10 may have a plurality of control circuit boards 50. The first and second position detection circuits may be provided on a control circuit board separate from the control circuit board 50.

[0029] The planar member 60 is made of a transparent material such as glass or resin, and one surface 60a of the planar member 60 is used as an indication surface (operation surface) for indicating a position with a first indicator such as an electronic pen and a second indicator such as a finger or an indication pen. The second sensor 40 and the display device 30 are disposed on the surface of the planar member 60 opposite to the one surface 60a.

[0030] The planar member 60 has a shape slightly larger than the detection areas of the indicators of the first sensor 20 and the second sensor 40. That is, in the planar member 60 in Fig. 1, an area 61 surrounded by a dotted line is an area corresponding to the detection areas of the indicators of the first sensor 20 and the second sensor 40, and a frame area 62 is formed around the area 61. Although not shown, the planar member 60 may be formed so that the frame area 62 is made opaque and only the area 61 is kept transparent by, for example, applying silk screen printing to the frame area 62.

[0031] The housing 70 is made of, for example, synthetic resin. A recess 71 is formed in the housing 70 for housing the first sensor 20, the display device 30, the second sensor 40, and the control circuit board 50. After the first sensor 20, the display device 30, the second sensor 40, and the control circuit board 50 are housed in the recess 71, the frame region 62 of the planar member 60 is joined to the frame region 72 of the housing 70 by, for example, an adhesive, thereby closing the recess 71 and assembling the electronic device 10.

[0032] It should be noted that the first sensor 20 may be embedded in the chassis of the display device 30 , and the second sensor 40 may be disposed above the first sensor 20 and the display device 30 .

[0033] Next, a configuration example of the electromagnetic induction type first sensor 20 and the position detection circuit 200 will be described with reference to Fig. 2. An electronic pen 23 as an example of a first indicator used together with the first sensor 20 of this example has a built-in resonant circuit composed of a coil 23L and a capacitor 23C connected in parallel to the coil 23L.

[0034] The first sensor 20 is configured by arranging the X-axis direction loop coil group 22X on one surface of the wiring board 21 (see FIG. 1) and arranging the Y-axis direction loop coil group 22Y on the other surface of the wiring board 21. The X-axis direction loop coil group 22X and the Y-axis direction loop coil group 22Y each consist of a plurality of rectangular loop coils. In this embodiment, n loop coils are arranged in the X-axis direction and m loop coils are arranged in the Y-axis direction. The loop coils of the X-axis direction loop coil group 22X and the Y-axis direction loop coil group 22Y are arranged so as to overlap each other.

[0035] The loop coils constituting the X-axis direction loop coil group 22X are arranged so as to overlap one another at equal intervals in the horizontal direction (X-axis direction) of the detection area for detecting the position indicated by the electronic pen 23. The loop coils constituting the Y-axis direction loop coil group 22Y are arranged so as to overlap one another at equal intervals in the vertical direction (Y-axis direction) of the detection area.

[0036] A position detection circuit 200 is connected to the first sensor 20. The position detection circuit 200 includes a selection circuit 201, an oscillator 202, a current driver 203 constituting a transmission amplifier, a transmission / reception switching circuit 204, a reception amplifier 205, a detection circuit 206, a low-pass filter 207, a sample-and-hold circuit 208, an A / D (Analog to Digital) conversion circuit 209, and a control circuit 210.

[0037] The X-axis direction loop coil group 22X and the Y-axis direction loop coil group 22Y are connected to a selection circuit 201. The selection circuit 201 sequentially selects one of the two loop coil groups 22X and 22Y under the control of a control circuit 210.

[0038] The oscillator 202 generates an AC signal with a frequency of f0. This AC signal is supplied to a current driver 203 where it is converted into a current and then sent to a transmission / reception switching circuit 204. Under the control of a control circuit 210, the transmission / reception switching circuit 204 switches the connection destination (transmission side terminal T, reception side terminal R) to which the loop coil selected by the selection circuit 201 is connected at predetermined time intervals. The current driver 203 is connected to the transmission side terminal T, and the reception side terminal R is connected to a reception amplifier 205.

[0039] Therefore, during transmission, an AC signal converted into a current by the current driver 203 is supplied to the loop coil selected by the selection circuit 201 via the transmission side terminal T of the transmission / reception switching circuit 204. During reception, an induced voltage generated in the loop coil selected by the selection circuit 201 is supplied to the reception amplifier 205 via the selection circuit 201 and the reception side terminal R of the transmission / reception switching circuit 204, where it is amplified and sent to the detection circuit 206.

[0040] The induced voltage amplified in receiving amplifier 205 is detected by detection circuit 206 and supplied to A / D conversion circuit 209 via low-pass filter 207 and sample-and-hold circuit 208. A / D conversion circuit 209 converts the signal supplied via low-pass filter 207 and sample-and-hold circuit 208 from an analog signal to a digital signal, and supplies the digital signal to control circuit 210.

[0041] The control circuit 210 performs control to detect the indicated position. That is, the control circuit 210 controls the selection of the loop coil in the selection circuit 201, the signal switching in the transmission / reception switching circuit 204, the timing of the sample and hold circuit 208, and the like.

[0042] The control circuit 210 switches the transmission / reception switching circuit 204 to connect it to the transmission side terminal T, thereby controlling the energization of the loop coil selected by the selection circuit 201 from the X-axis direction loop coil group 22X or the Y-axis direction loop coil group 22Y to emit a magnetic field. The resonant circuit of the electronic pen 23 receives the magnetic field emitted from the loop coil, stores magnetic energy, and operates to transmit a magnetic field based on the stored magnetic energy to the first sensor 20.

[0043] Next, the control circuit 210 switches the transmission / reception switching circuit 204 to connect it to the reception side terminal R. Then, an induced voltage is generated in each of the loop coils of the X-axis direction loop coil group 22X and the Y-axis direction loop coil group 22Y by the magnetic field transmitted from the electronic pen 23, which is a position indicator.

[0044] Based on the voltage value of the induced voltage generated in each loop coil, the control circuit 210 calculates the coordinate values ​​of the indicated position in the X-axis direction and the Y-axis direction in the detection area of ​​the first sensor 20. Then, the control circuit 210 detects the position indicated by the electronic pen 23 from the calculated coordinate values, and an external host (PC) that receives the detection result from the control circuit 210 controls the screen displayed on the display device 30.

[0045] The control circuit 210 is connected to the control circuit 410 of the position detection circuit 400 of the second sensor 40, and a synchronization signal is exchanged between the control circuit 410 to synchronize the detection operation of the position indicated by the electronic pen with the detection operation of the position indicated by the finger or the position indicator. For example, the control circuit 210 transmits a start signal to the control circuit 410 indicating the start of the detection operation of the position indicated by the electronic pen. The control circuit 410 may also transmit a start signal to the control circuit 210 indicating the start of the detection operation of the position indicated by the finger or the position indicator. Apart from the control circuit 210 and the control circuit 410, a control unit may be provided between the control circuit 210 and the control circuit 410 to synchronize the detection operation of the position indicated by the electronic pen with the detection operation of the position indicated by the finger or the position indicator.

[0046] Next, a configuration example of the second sensor 40 and the position detection circuit 400 will be described with reference to Fig. 3. The second sensor 40 is configured as a cross-point capacitive sensor to realize multi-touch detection for simultaneously detecting multiple fingers.

[0047] The second sensor 40 is configured by forming an electrode group consisting of a plurality of light-transmitting electrodes on, for example, one surface (the surface opposite to the surface facing the display screen 33 of the display device 30) of a transparent substrate 41. The transparent substrate 41 is made of, for example, a glass substrate or a resin film substrate.

[0048] The electrode group is composed of a plurality of first electrodes 42X each formed in the Y-axis direction (vertical direction) and a plurality of second electrodes 42Y each formed in the X-axis direction (horizontal direction) perpendicular to the Y-axis direction. The first electrodes 42X are arranged at predetermined intervals in the X-axis direction. The second electrodes 42Y are arranged at predetermined intervals in the Y-axis direction. The first electrodes 42X and the second electrodes 42Y are made of a light-transmitting conductive material, for example, a conductor made of an ITO film or a metal mesh.

[0049] The first electrode 42X and the second electrode 42Y are formed on the same surface of the transparent substrate 41. Therefore, in a cross-point region where the first electrode 42X and the second electrode 42Y intersect at right angles, an insulating material is disposed between the first electrode 42X and the second electrode 42Y, so that the first electrode 42X and the second electrode 42Y are electrically insulated from each other.

[0050] A position detection circuit 400 is connected to the second sensor 40. The position detection circuit 400 includes a transmission signal generation circuit 401, a transmission electrode selection circuit 402, a reception electrode selection circuit 404, a reception signal processing circuit 405, a position information output circuit 406, and a control circuit 410.

[0051] The position detection circuit 400, under the control of the control circuit 410, discretely executes position detection processing at a predetermined time interval, for example, every 10 msec, to individually detect multiple position indications by the second indicator on the second sensor 40 and obtain respective position detection results.

[0052] The transmission signal generating circuit 401 and the transmission electrode selecting circuit 402 constitute a transmission signal supplying circuit, and the receiving electrode selecting circuit 404 and the receiving signal processing circuit 405 constitute a signal receiving circuit. The first electrode 42X is a receiving electrode, and the second electrode 42Y is a transmitting electrode.

[0053] The transmission signal generating circuit 401 supplies a predetermined transmission signal to the transmission electrode selection circuit 402 at a predetermined timing according to the control of the control circuit 410. As the predetermined transmission signal, for example, an orthogonal spreading code or the like can be used (for example, see JP 2021-99827 A).

[0054] The transmission electrode selection circuit 402 selects a predetermined second electrode 42Y (transmission electrode) in accordance with the selection control of the control circuit 410. A transmission signal from the transmission signal generation circuit 401 is simultaneously supplied to a plurality of second electrodes 42Y (all, even-numbered, or odd-numbered) selected by the transmission electrode selection circuit 402. Note that the transmission electrode selection circuit 402 may not be provided, and the transmission signal may be transmitted directly from the transmission signal generation circuit 401 to all of the second electrodes 42Y.

[0055] The receiving electrode selection circuit 404 selects multiple (all, even-numbered, or odd-numbered) first electrodes 42X under the control of the control circuit 410, and supplies the receiving signals simultaneously received from the selected first electrodes 42X to the receiving signal processing circuit 405.

[0056] Based on the control of the control circuit 410, the reception signal processing circuit 405 detects a signal change in the reception signal caused when a second indicator such as a finger or a position indicator indicates a position on the second sensor 40 at the first electrode 42X, and supplies the detection output to the position information output circuit 406.

[0057] Based on the control by the control circuit 410, the position information output circuit 406 generates a coordinate output as a position detection result, which is an indicated position detection signal corresponding to the position indicated by a second indicator such as a finger or a position pointer, from the first electrode 42X where a signal change in the received signal has occurred and the second electrode 42Y to which a transmission signal is supplied at that time, from the detection output of the received signal processing circuit 405, and outputs the coordinate output to the control circuit 410.

[0058] The external host (PC) receives the position detection result from the position information output circuit 406 via the control circuit 210 and controls the screen displayed on the display device 30 in accordance with the position detection result.

[0059] As described above, the position detection device of this embodiment includes the first sensor 20 and the position detection circuit 200 of the electromagnetic induction type, and also includes the second sensor 40 and the position detection circuit 400 of the capacitance type, and can simultaneously detect position indications by a first indicator (e.g., an electronic pen) and a second indicator (e.g., a finger or a position indicator). The electronic device 10 can perform processing such as changing and controlling the display image of the display device 30 according to the detection results of the first indicator and the detection results of the second indicator.

[0060] Next, an example of the control configuration of the display device 30 will be described with reference to Fig. 4. The display device 30 includes a display module 301 (corresponding to the "display" of the present invention), a backlight module 302, a gate driver circuit 303, and a source driver circuit 304. The control circuit 34 is mounted on the control circuit board 50 (see Fig. 1). The gate driver circuit 303 and the control circuit 34 are connected via four clock lines (not shown).

[0061] The display module 301 includes row signal lines GL1 to GLn arranged in the vertical direction, column signal lines SL1 to SLm arranged in the horizontal direction, and display pixels 32 (image elements) arranged at each intersection of the row signal lines GL1 to GLn and the column signal lines SL1 to SLm. The display module 301 drives a corresponding one of the row signal lines GL1 to GLn in accordance with gate signals VG1 to VGn transmitted from a gate driver circuit 303, and drives each display pixel 32 corresponding to the source signals VS1 to VSm with the luminance indicated by the source signals VS1 to VSm transmitted from a source driver circuit 304.

[0062] The row signal lines GL1 to GLn are, for example, gate lines, and n lines are arranged in the vertical direction in the display device 30. The row signal lines GL1 to GLn are driven by corresponding gate signals VG1 to VGn transmitted from a gate driver circuit 303, and relay the exchange of charges between the gate electrodes of the display pixels 32 that are located at the intersections with the column signal lines SL1 to SLm and the gate driver circuit 303.

[0063] The column signal lines SL1 to SLm are, for example, source lines, and m of them are arranged in the horizontal direction in the display device 30. The column signal lines SL1 to SLm are driven by corresponding source signals VS1 to VSm transmitted from a source driver circuit 304, and relay the exchange of charges between the source driver circuit 304 and the source electrodes of the display pixels 32 that correspond to the intersections with the row signal lines GL1 to GLn.

[0064] The display pixels 32 are, for example, liquid crystal image elements, and a total of n×m display pixels 32 are arranged at the intersections of the row signal lines GL1 to GLn and the column signal lines SL1 to SLm in the display device 30. One of the row signal lines GL1 to GLn is connected to a gate electrode of each display pixel 32, and one of the column signal lines SL1 to SLm is connected to a source electrode of each display pixel 32. When a charge is supplied to the gate electrode via the row signal lines GL1 to GLn connected to the gate electrode, each display pixel 32 displays a corresponding image with a luminance according to the electric potential of the column signal lines SL1 to SLm connected to the source electrode.

[0065] The backlight module 302 is a light source disposed on the rear side of the display module 301, and irradiates the display module 301 with light from the rear side.

[0066] The gate driver circuit 303 is a circuit that drives the row signal lines GL1 to GLn, and is disposed within the display module 301 when the display device 30 is viewed from the display screen 33 side. The gate driver circuit 303 drives the row signal lines GL1 to GLn in sequence by outputting gate signals VG1 to VGn to the corresponding row signal lines GL1 to GLn at timings according to clock signals CLK1 to CLK4 output from the control circuit 34. The gate driver circuit 303 also supplies and extracts electric charges to and from the gate electrodes of the corresponding display pixels 32 via the driven row signal lines GL1 to GLn.

[0067] The source driver circuit 304 is a circuit for driving the column signal lines SL1 to SLm, and is disposed below the display module 301 when the display device 30 is viewed from the display screen 33 side. The source driver circuit 304 outputs source signals VS1 to VSm having potentials set for each of the column signal lines SL1 to SLm by the control circuit 34 to the corresponding column signal lines SL1 to SLn at timing according to the control circuit 34. The source driver circuit 304 supplies the potentials of the source signals VS1 to VSm corresponding to the display pixels 32 to the source electrodes of the display pixels 32 corresponding to the intersections of the row signal lines GL1 to GLn driven by the gate driver circuit 303 and the column signal lines SL1 to SLm.

[0068] The control circuit 34 is a circuit for controlling the display device 30. When the gate driver circuit 303 starts driving the row signal lines GL1 to GLm, the control circuit 34 generates a start signal which is a signal indicating the start of driving, and outputs the start signal to the gate driver circuit 303. The control circuit 34 also generates clock signals CLK1 to CLK4 for operating the gate driver circuit 303, and outputs the clock signals CLK1 to CLK4 to the gate driver circuit 303 via four clock lines.

[0069] Furthermore, the control circuit 34 generates a clock signal for operating the source driver circuit 304, and outputs the clock signal to the source driver circuit 304. The control circuit 34 also sets a potential to be supplied to the source electrodes of the corresponding display pixels 32 via the column signal lines SL1 to SLm, and outputs a signal having information about the set potential to the source driver circuit 304.

[0070] (Description of the assignment) In the above-mentioned electronic device 10, in order to realize miniaturization of the electronic device 10 while maintaining the size of the flat display (display module 301), it is an issue to deal with narrowing the frame by narrowing the width of the frame (picture frame) surrounding the flat display (display module 301). In order to deal with narrowing the frame, the electronic device 10 is required to reduce the arrangement space for loop coils and signal lines used in an indication position detection device that detects the position indicated by a pointer.

[0071] However, when both an electromagnetic induction type pointing position detection device and a capacitance type pointing position detection device are mounted on one electronic device 10, the loop coil used in the electromagnetic induction type pointing position detection device and the signal line used in the capacitance type pointing position detection device for transmitting a transmission signal and receiving a reception signal may be disposed close to each other. In this case, the loop coil and the signal line may be magnetically coupled (interfered with each other), causing electromagnetic noise to be mixed into the loop coil from the signal line used for transmitting the transmission signal, or electromagnetic noise to be mixed into the signal line used for receiving the reception signal from the loop coil. When electromagnetic noise is mixed into the loop coil from the signal line used for transmitting the transmission signal, the S / N ratio of the magnetic field transmitted from the electronic pen 23 and received by the loop coil decreases, and the detection accuracy of the pointing position in the electromagnetic induction type pointing position detection device decreases. Also, when electromagnetic noise is mixed into the signal line used for receiving the reception signal from the loop coil, the S / N ratio of the reception signal decreases, and the detection accuracy of the pointing position in the capacitance type pointing position detection device decreases.

[0072] For example, as shown in Fig. 5, the loop coils 22X1 and 22Y1 used in the electromagnetic induction type pointing position detection device may be arranged close to the signal line 42X1 used to transmit a transmission signal and the signal line 42Y1 used to receive a reception signal in the capacitance type pointing position detection device. In this case, the loop coil 22X1 and the signal line 42X1 are magnetically coupled (interfered) with each other, so that electromagnetic noise is mixed into the loop coil 22X1 from the signal line 42X1 used to transmit a transmission signal, and the S / N ratio of the magnetic field transmitted from the electronic pen 23 and received by the loop coil 22X1 is reduced, and the detection accuracy of the pointing position in the electromagnetic induction type pointing position detection device is reduced. In addition, the loop coil 22Y1 and the signal line 42Y1 are magnetically coupled (interfered) with each other, so that electromagnetic noise is mixed into the signal line 42Y1 used to receive a reception signal from the loop coil 22Y1, and the S / N ratio of the reception signal is reduced, and the detection accuracy of the pointing position in the capacitance type pointing position detection device is reduced.

[0073] Furthermore, when an electromagnetic induction type pointing position detection device and a capacitance type pointing position detection device are mounted on one electronic device 10, a loop coil used in the electromagnetic induction type pointing position detection device, a signal line used in the capacitance type pointing position detection device, and a signal line (e.g., a clock line) used to transmit a drive signal (e.g., a clock signal) that drives a flat display (display module 301) may be arranged close to each other. In this case, electromagnetic noise may be mixed from the signal line used to transmit the drive signal into the loop coil used in the electromagnetic induction type pointing position detection device and the signal line used to receive a reception signal in the capacitance type pointing position detection device, resulting in a decrease in the S / N ratio of the magnetic field transmitted from the electronic pen 23 and received by the loop coil, thereby decreasing the accuracy of position detection in the electromagnetic induction type pointing position detection device, or a decrease in the S / N ratio of the received signal, thereby decreasing the accuracy of position detection in the capacitance type pointing position detection device.

[0074] 6, for example, a loop coil (not shown) used in an electromagnetic induction-type pointing position detection device or a signal line (not shown) used in a capacitance-type pointing position detection device may be arranged close to a signal line (clock line) used to transmit a drive signal (clock signals CLK1 to CLK4) for driving a flat display (display module 301). In this case, electromagnetic noise may be mixed from the clock line used to transmit the clock signal into the loop coil used in the electromagnetic induction-type pointing position detection device or the signal line used to receive a reception signal in the capacitance-type pointing position detection device, resulting in a decrease in the S / N ratio of the magnetic field transmitted from the electronic pen 23 and received by the loop coil, thereby decreasing the accuracy of position detection in the electromagnetic induction-type pointing position detection device, or a decrease in the S / N ratio of the received signal, thereby decreasing the accuracy of position detection in the capacitance-type pointing position detection device.

[0075] (Description of the configuration for solving the problem) In order to solve the above-mentioned problems, the electronic device 10 (pointing position detection device) in this embodiment includes a first transmitting unit (X-axis direction loop coil group 22X and Y-axis direction loop coil group 22Y) that transmits a first transmission signal (electromagnetic induction signal) related to a first process of detecting a pointing position by a pointer (electronic pen 23) by electromagnetic induction, a second transmitting unit (transmission signal generating circuit 401) that transmits a second transmission signal (transmission signal) related to a second process of detecting a pointing position by a pointer (finger or position pointer (electrostatic pen)) by electrostatic capacitance, and a first receiving unit (X-axis direction loop coil group 22X and Y-axis direction loop coil group 22Y) that receives a first reception signal (electromagnetic induction signal) related to the first process during the transmission period of the second transmission signal. In the same period, the waveform of the first transmission signal (electromagnetic induction signal) and the waveform of the second transmission signal (transmission signal) are orthogonal to each other. Here, based on the principle of detecting the position pointed by the pointer (electronic pen 23) by the electromagnetic induction method, since the center frequency of the first transmission signal (electromagnetic induction signal) and the center frequency of the reception signal (electromagnetic induction signal) are the same in a frequency spectrum represented by the amplitude of the frequency components of each sine wave as a function of frequency, during the reception period of the first reception signal (electromagnetic induction signal), the waveform of the first reception signal (electromagnetic induction signal) and the waveform of the second transmission signal (transmission signal) are orthogonal, that is, the inner product of the waveform of the first reception signal (electromagnetic induction signal) and the waveform of the second transmission signal (transmission signal) is 0, and as a result, it is possible to detect a first reception signal in which the inclusion of electromagnetic noise due to the transmission of the second transmission signal is suppressed. When the waveform of the first transmission signal (electromagnetic induction signal) and the waveform of the second transmission signal (transmission signal) are orthogonal during the same period, for example, the value obtained by subtracting the wave number of the second transmission signal from the wave number of the first transmission signal is a positive or negative integer. In the frequency spectrum, the signal power of the second transmission signal (transmission signal) is 0 at the center frequency of the first reception signal (electromagnetic induction signal).

[0076] In this embodiment, in order to correctly demodulate the first reception signal (electromagnetic induction signal) even if electromagnetic noise is mixed into the loop coil used to receive the first reception signal (electromagnetic induction signal) from the signal line used to transmit the second transmission signal (transmission signal) during the reception period of the first reception signal (electromagnetic induction signal), the first transmission signal (electromagnetic induction signal) and the second transmission signal (transmission signal) are transmitted in advance during the same period so as to be orthogonal to each other. The concept of these two orthogonal signal waveforms is based on Orthogonal Frequency Division Multiplexing (OFDM), which is commonly used in the field of wireless communication such as wireless LAN and 3GPP (registered trademark) (Third Generation Partnership Project).

[0077] That is, as a process at the time of receiving the first reception signal (electromagnetic induction signal), the first reception signal is multiplied by an internal signal corresponding to the second transmission signal (transmission signal) and integrated for a predetermined period, thereby extracting (demodulating) the first reception signal in which the inclusion of electromagnetic noise due to the transmission of the second transmission signal is suppressed. In other words, it becomes possible to separate noise unrelated to the characteristics of the first reception signal to be detected, and it is possible to suppress a decrease in the accuracy of detecting the pointing position by the pointer (electronic pen 23) by the electromagnetic induction method. Here, the internal signal corresponding to the second transmission signal (transmission signal) is a spreading code capable of restoring the second transmission signal, a locally generated signal / data that matches the frequency / pattern of the second transmission signal, etc. When the demodulation process is performed digitally, a correlation calculation process or a discrete Fourier transform process (DFT: Discrete Fourier Transform) is performed. When the demodulation process is performed analogically, an orthogonal demodulation process is performed. In addition, the dot product of the waveform of the first received signal (electromagnetic induction signal) and the waveform of the second transmitted signal (transmitted signal) does not necessarily have to be 0, and may be equal to or less than a predetermined value so long as it is possible to extract a first received signal in which the inclusion of electromagnetic noise due to the transmission of the second transmitted signal is suppressed.

[0078] In the present embodiment, the electronic device 10 (pointing position detection device) includes a first transmitting unit (X-axis direction loop coil group 22X and Y-axis direction loop coil group 22Y) that transmits a first transmitting signal (electromagnetic induction signal) related to a first process of detecting a pointing position by a pointer (electronic pen 23) by electromagnetic induction, a second transmitting unit (transmitting signal generating circuit 401) that transmits a second transmitting signal (transmitting signal) related to a second process of detecting a pointing position by a pointer (finger or position pointer (capacitive pen)) by electrostatic capacitance, and a second receiving unit (receiving electrode selecting circuit 404) that receives a second receiving signal related to the second process during a transmission period of the first transmitting signal (electromagnetic induction signal). In the same period, the waveform of the first transmitting signal (electromagnetic induction signal) and the waveform of the second transmitting signal (transmitting signal) are orthogonal to each other. Here, based on the principle of detecting the position pointed by the indicator (finger or position indicator (electrostatic pen)) by the capacitive method, the center frequency of the second transmission signal (transmission signal) and the center frequency of the second reception signal are the same in the frequency spectrum, so that during the reception period of the second reception signal, the waveforms of the first transmission signal (electromagnetic induction signal) and the second reception signal are orthogonal, that is, the inner product of the waveforms of the first transmission signal (electromagnetic induction signal) and the second reception signal is 0, and as a result, it is possible to detect a second reception signal in which the inclusion of electromagnetic noise due to the transmission of the first transmission signal is suppressed. When the waveforms of the first transmission signal (electromagnetic induction signal) and the second transmission signal (transmission signal) are orthogonal during the same period, for example, the value obtained by subtracting the wave number of the second transmission signal from the wave number of the first transmission signal is a positive or negative integer. Note that, in the frequency spectrum, the signal power of the first transmission signal (electromagnetic induction signal) is 0 at the center frequency of the second reception signal.

[0079] In this embodiment, in order to enable the second reception signal to be correctly demodulated even if electromagnetic noise is mixed into the signal line used to receive the second reception signal from the loop coils (X-axis direction loop coil group 22X and Y-axis direction loop coil group 22Y) used to transmit the first transmission signal (electromagnetic induction signal), during the reception period of the second reception signal, the first transmission signal (electromagnetic induction signal) and the second transmission signal (transmission signal) are transmitted in advance during the same period so as to be orthogonal to each other.

[0080] That is, as a process for receiving the second reception signal, the second reception signal is multiplied by an internal signal corresponding to the first transmission signal (electromagnetic induction signal) and integrated for a predetermined period, thereby extracting (demodulating) the second reception signal in which the inclusion of electromagnetic noise due to the transmission of the first transmission signal (electromagnetic induction signal) is suppressed. In other words, it becomes possible to separate noise unrelated to the characteristics of the second reception signal to be detected, and it is possible to suppress a decrease in the accuracy of detecting the position indicated by the pointer (finger or position pointer (electrostatic pen)) by the capacitive method. Here, the internal signal corresponding to the first transmission signal (electromagnetic induction signal) is a spreading code capable of restoring the first transmission signal, a locally generated signal / data that matches the frequency / pattern of the first transmission signal, etc. In addition, when performing demodulation processing digitally, correlation calculation processing or discrete Fourier transform processing (DFT: Discrete Fourier Transform) is performed. In addition, when performing demodulation processing analogically, orthogonal demodulation processing is performed. In addition, the dot product of the waveform of the first transmission signal (electromagnetic induction signal) and the waveform of the second reception signal does not necessarily have to be 0, and may be below a predetermined value so long as it is possible to extract a second reception signal in which the inclusion of electromagnetic noise due to the transmission of the first transmission signal is suppressed.

[0081] FIG. 7 is a waveform diagram related to the process of detecting the position pointed by the indicator. In FIG. 7, the first transmission signal 5A represents the waveform (time change) of the transmission signal (electromagnetic induction signal) related to the process of detecting the position pointed by the indicator (electronic pen 23) by the electromagnetic induction method. The first reception signal 5B represents the waveform (time change) of the reception signal (electromagnetic induction signal) related to the process of detecting the position pointed by the indicator (electronic pen 23) by the electromagnetic induction method. The electromagnetic energy 5C represents the waveform (time change) of the current flowing through the resonance circuit of the electronic pen 23 after receiving the first transmission signal 5A (electromagnetic induction signal). The second transmission signal 5D represents the waveform (time change) of the transmission signal related to the process of detecting the position pointed by the indicator (finger or position indicator (electrostatic pen)) by the electrostatic capacitance method. The second reception signal 5E represents the waveform (time change) of the reception signal related to the process of detecting the position pointed by the indicator (finger or position indicator (electrostatic pen)) by the electrostatic capacitance method. The horizontal axis represents time (t) and the vertical axis represents magnitude for the first transmission signal 5A, the first reception signal 5B, the electromagnetic energy 5C, the second transmission signal 5D, and the second reception signal 5E. Note that the horizontal axis represents time, and all of the first transmission signal 5A, the first reception signal 5B, the electromagnetic energy 5C, the second transmission signal 5D, and the second reception signal 5E are shown on the same time axis.

[0082] As shown in the first transmission signal 5A, during periods D1 and D4, the control circuit 210 switches the transmission / reception switching circuit 204 to connect it to the transmission side terminal T, thereby controlling the energization of the loop coil selected by the selection circuit 201 from the X-axis direction loop coil group 22X or the Y-axis direction loop coil group 22Y, thereby transmitting a magnetic field toward the electronic pen 23.

[0083] As shown in the first reception signal 5B, in period D2, the control circuit 210 switches the transmission / reception switching circuit 204 to connect to the reception side terminal R, thereby causing each loop coil of the X-axis direction loop coil group 22X and the Y-axis direction loop coil group 22Y to receive the magnetic field transmitted from the electronic pen 23. An induced voltage is generated in each loop coil of the X-axis direction loop coil group 22X and the Y-axis direction loop coil group 22Y by the received first reception signal 5B. The first reception signal 5B received from the electronic pen 23 by each loop coil of the X-axis direction loop coil group 22X and the Y-axis direction loop coil group 22Y gradually decreases over time.

[0084] As shown in electromagnetic energy 5C, in period D1, a magnetic field is transmitted from the loop coil, which is energized by transmitting the first transmission signal 5A (electromagnetic induction signal), toward the electronic pen 23, so that the magnetic energy stored in the resonant circuit of the electronic pen 23 gradually increases. Then, in periods D2 and D3 when the transmission of the magnetic field from the loop coil toward the electronic pen 23 is stopped, the electromagnetic energy stored in the resonant circuit of the electronic pen 23 gradually decreases as the electronic pen 23 transmits the first reception signal 5B (electromagnetic induction signal) to each of the loop coils of the X-axis loop coil group 22X and the Y-axis loop coil group 22Y.

[0085] As shown in the second transmission signal 5D, in periods D1 to D4, the control circuit 410 controls the transmission signal generating circuit 401 to transmit a transmission signal to the second electrode 42Y (transmission electrode) through the transmission electrode selection circuit 402. The periods D1 and D4 during which the loop coil is energized and controlled by the transmission of the first transmission signal 5A (electromagnetic induction signal) overlap at least a part of the transmission periods D1 to D4 of the second transmission signal 5D transmitted to the second electrode 42Y (transmission electrode). Note that the start and end points of the period during which the loop coil is energized and controlled by the transmission of the first transmission signal 5A (electromagnetic induction signal) may be the same as the start and end points of the transmission period of the second transmission signal 5D transmitted to the second electrode 42Y (transmission electrode).

[0086] As shown in the second reception signal 5E, in periods D1 to D4, the control circuit 410 controls the reception electrode selection circuit 404 to receive a reception signal from the first electrode 42X.

[0087] In this embodiment, during a period D11 of the period D1, the waveform of the first transmission signal 5A transmitted to control energization of the loop coil is orthogonal to the waveform of the second transmission signal 5D transmitted to the second electrode 42Y (transmission electrode). Here, based on the principle of detecting a position pointed to by a pointer (finger or position pointer (electrostatic pen)) by the capacitive method, the center frequency of the second reception signal 5E received from the first electrode 42X is the same as the center frequency of the second transmission signal 5D transmitted to the second electrode 42Y (transmission electrode) in the frequency spectrum, so during a reception period R1 of the second reception signal 5E, which is equal to the period D11, the waveform of the first transmission signal 5A transmitted to control energization of the loop coil is orthogonal to the waveform of the second reception signal 5E received from the first electrode 42X. 7, the value obtained by subtracting the number of waves (3 waves) of the second transmission signal 5D transmitted to the second electrode 42Y (transmission electrode) from the number of waves (6 waves) of the first transmission signal 5A transmitted to control the energization of the loop coil during the same period D11 is a positive integer (3 waves). Note that in this embodiment, the phase of the second transmission signal 5D transmitted to the second electrode 42Y (transmission electrode) is adjusted (e.g., shifted by 90 degrees) to avoid abrupt changes in the second transmission signal 5D at the start and end of the period D11, and suppresses a decrease in orthogonality between the waveform of the first transmission signal 5A transmitted to control the energization of the loop coil and the waveform of the second transmission signal 5D transmitted to the second electrode 42Y (transmission electrode) when a shift in the transmission timing of the second transmission signal 5D occurs.

[0088] In this embodiment, in order to correctly demodulate the second reception signal 5E during the reception period R1 of the second reception signal 5E even if electromagnetic noise is mixed into the signal line used to receive the second reception signal 5E from the first electrode 42X from the loop coils (X-axis direction loop coil group 22X and Y-axis direction loop coil group 22Y) used to control the current flow of the first transmission signal 5A, the first transmission signal 5A and the second transmission signal 5D are transmitted in advance in the same period D11 so as to be orthogonal to each other.

[0089] That is, as a process for receiving the second reception signal 5E, the second reception signal 5E received in the reception period R1 is multiplied by an internal signal corresponding to the first transmission signal 5A transmitted to control the energization of the loop coil, and integrated for a predetermined period of time. This makes it possible to extract (demodulate) the second reception signal 5E in which the inclusion of electromagnetic noise due to the transmission of the first transmission signal 5A is suppressed. In other words, it becomes possible to separate noise unrelated to the characteristics of the second reception signal 5E to be detected, and it is possible to suppress a decrease in the accuracy of detecting the position indicated by the indicator (finger or electrostatic pen) using the capacitive method.

[0090] Furthermore, based on the principle of detecting the position indicated by the pointer (electronic pen 23) using the electromagnetic induction method, the center frequency of the first transmission signal 5A transmitted to control the flow of electricity to the loop coil is the same as the center frequency of the first reception signal 5B (electromagnetic induction signal) received from the electronic pen 23 in the frequency spectrum. Therefore, during the reception period R2 in which the first reception signal 5B transmitted from the electronic pen 23 is received during the period D2, the waveform of the first reception signal 5B, for example, the waveform of the resonant frequency in the resonant circuit of the electronic pen 23 (the resonant frequency changes depending on the writing pressure of the electronic pen 23), is orthogonal to the waveform of the second transmission signal 5D transmitted to the second electrode 42Y (transmission electrode), that is, the dot product of the waveform of the first reception signal 5B and the waveform of the second transmission signal 5D is zero.

[0091] In addition, in the reception period R2 in which the first reception signal 5B is received, the waveform of the first reception signal 5B (electromagnetic induction signal) received from the electronic pen 23 and the waveform of the second reception signal 5E received from the first electrode 42X are orthogonal, that is, the inner product of the waveforms of the first reception signal 5B and the second reception signal 5E is 0. In the same period R2, the value obtained by subtracting the number of waves of the second reception signal 5E (3 waves) from the number of waves of the first reception signal 5B (6 waves) is a positive integer (3 waves).

[0092] In this embodiment, in order to enable the first reception signal 5B to be correctly demodulated even if electromagnetic noise is mixed into the loop coils (X-axis direction loop coil group 22X and Y-axis direction loop coil group 22Y) used to receive the first reception signal 5B from the electronic pen 23 from the signal line used to transmit the second transmission signal 5D to the second electrode 42Y (transmission electrode) during the reception period R2 of the first reception signal 5B, the first transmission signal 5A and the second transmission signal 5D are transmitted in advance in the same period D11, which are orthogonal to each other.

[0093] That is, as a process for receiving the first reception signal 5B, the first reception signal 5B received in the reception period R2 is multiplied by an internal signal corresponding to the second transmission signal 5D transmitted to the second electrode 42Y (transmission electrode) and integrated for a predetermined period of time. This makes it possible to extract (demodulate) the first reception signal 5B in which the inclusion of electromagnetic noise due to the transmission of the second transmission signal 5D is suppressed. In other words, it becomes possible to separate noise unrelated to the characteristics of the first reception signal 5B to be detected, and it is possible to suppress a decrease in the accuracy of detecting the position indicated by the pointer (electronic pen 23) by the electromagnetic induction method.

[0094] In addition, a period G corresponding to a guard interval is provided between the reception period R1 in which the second reception signal 5E is received from the first electrode 42X and the reception period R2 in which the first reception signal 5B (electromagnetic induction signal) is received from the electronic pen 23. This has the effect of mitigating the adverse effects (reduction in the detection accuracy of the first reception signal 5B and the second reception signal 5E, and ultimately the detection accuracy of the pointing position) that may occur when there is a delay in the timing of receiving the second reception signal 5E from the first electrode 42X or a delay in the timing of receiving the first reception signal 5B from the electronic pen 23, and has the effect of ensuring time until the waveform of the first reception signal 5B received from the electronic pen 23 stabilizes after the first transmission signal 5A is transmitted to control the flow of current to the loop coil.In addition, when the second transmission signal 5D transmitted to the second electrode 42Y (transmission electrode) is a spread code and the spread code is switched, for example, from negative (-) to positive (+) between the reception period R1 and the reception period R2 (see Figure 7), it is possible to prevent the detection accuracy of the first reception signal 5B received from the electronic pen 23 from decreasing due to the influence of the switching.

[0095] In the present embodiment, the electronic device 10 (pointing position detection device) includes a first transmitting unit (X-axis direction loop coil group 22X and Y-axis direction loop coil group 22Y) that transmits a first transmission signal (electromagnetic induction signal) related to a first process of detecting a pointing position by a pointer (electronic pen 23) by electromagnetic induction, a second transmitting unit (control circuit 34) that transmits a second transmission signal (clock signal) related to a second process of driving a display (display module 301), and a first receiving unit (X-axis direction loop coil group 22X and Y-axis direction loop coil group 22Y) that receives a first reception signal (electromagnetic induction signal) related to the first process during a transmission period of the second transmission signal. In the same period, the waveform of the first transmission signal and the waveform of the second transmission signal are orthogonal to each other. Here, based on the principle of detecting the position pointed by the pointer (electronic pen 23) by the electromagnetic induction method, the center frequency of the first reception signal and the center frequency of the first transmission signal are the same in the frequency spectrum, so that the waveform of the first reception signal and the waveform of the second transmission signal are orthogonal during the reception period of the first reception signal, that is, the inner product of the waveform of the first reception signal and the waveform of the second transmission signal is 0, and as a result, it is possible to detect a first reception signal in which the inclusion of electromagnetic noise due to the transmission of the second transmission signal is suppressed. When the waveform of the first transmission signal and the waveform of the second transmission signal are orthogonal during the same period, for example, the value obtained by subtracting the wave number of the second transmission signal from the wave number of the first transmission signal is a positive or negative integer. Note that, in the frequency spectrum, the signal power density of the second transmission signal is 0 at the center frequency of the first reception signal.

[0096] In this embodiment, in order to enable the first reception signal to be correctly demodulated even if electromagnetic noise is mixed from the signal line (clock line) used to transmit the second transmission signal to the loop coil used to receive the first reception signal during the reception period of the first reception signal, a first transmission signal and a second transmission signal (clock signal) that are orthogonal to each other are transmitted in advance during the same period.

[0097] That is, as a process for receiving the first reception signal (electromagnetic induction signal), the first reception signal is multiplied by an internal signal corresponding to the second transmission signal (clock signal) and integrated for a predetermined period, thereby extracting (demodulating) the first reception signal in which the inclusion of electromagnetic noise due to the transmission of the second transmission signal is suppressed. In other words, it becomes possible to separate noise unrelated to the characteristics of the first reception signal to be detected, and it is possible to suppress a decrease in the accuracy of detecting the pointing position by the pointer (electronic pen 23) by the electromagnetic induction method. Here, the internal signal corresponding to the second transmission signal (clock signal) is a spreading code capable of restoring the second transmission signal, a locally generated signal / data that matches the frequency / pattern of the second transmission signal, etc. When the demodulation process is performed digitally, correlation calculation process or discrete Fourier transform process (DFT: Discrete Fourier Transform) is performed. When the demodulation process is performed analogically, orthogonal demodulation process is performed. In addition, the dot product of the waveform of the first received signal (electromagnetic induction signal) and the waveform of the second transmitted signal (clock signal) does not necessarily have to be 0, and may be equal to or less than a predetermined value so long as it is possible to extract a first received signal with reduced electromagnetic noise caused by the transmission of the second transmitted signal.

[0098] In this embodiment, the electronic device 10 (pointing position detection device) includes a first transmitting unit (transmission signal generating circuit 401) that transmits a first transmission signal (transmission signal) related to a first process of detecting a position pointed to by a pointer (finger or electrostatic pen) using a capacitive method, a second transmitting unit (control circuit 34) that transmits a second transmission signal (clock signal) related to a second process of driving a display (display module 301), and a first receiving unit (receiving electrode selection circuit 404) that receives a first reception signal related to the first process during a transmission period of the second transmission signal. In the same period, the waveform of the first transmission signal (transmission signal) and the waveform of the second transmission signal (clock signal) are orthogonal to each other. Here, based on the principle of detecting the position pointed by a pointer (finger or electrostatic pen) by the capacitive method, the center frequency of the first reception signal and the center frequency of the first transmission signal are the same in the frequency spectrum, so that during the reception period of the first reception signal, the waveform of the first reception signal and the waveform of the second transmission signal (clock signal) are orthogonal, that is, the inner product of the waveform of the first reception signal and the waveform of the second transmission signal is 0, and as a result, it is possible to detect a first reception signal in which the inclusion of electromagnetic noise due to the transmission of the second transmission signal is suppressed. When the waveform of the first transmission signal and the waveform of the second transmission signal are orthogonal, for example, the value obtained by subtracting the wave number of the second transmission signal from the wave number of the first transmission signal is a positive or negative integer. Note that, in the frequency spectrum, the signal power of the second transmission signal (clock signal) is 0 at the center frequency of the first reception signal.

[0099] In this embodiment, in order to enable the first reception signal to be correctly demodulated even if electromagnetic noise is mixed from the signal line (clock line) used to transmit the second transmission signal (clock signal) to the signal line used to receive the first reception signal during the reception period of the first reception signal, a first transmission signal and a second transmission signal that are orthogonal to each other are transmitted in advance during the same period.

[0100] That is, as a process for receiving the first reception signal, the first reception signal is multiplied by an internal signal corresponding to the second transmission signal (clock signal) and integrated for a predetermined period, thereby extracting (demodulating) the first reception signal in which the inclusion of electromagnetic noise due to the transmission of the second transmission signal is suppressed. In other words, it is possible to separate noise unrelated to the characteristics of the first reception signal to be detected, and it is possible to suppress a decrease in the accuracy of detecting the pointing position by the pointer (finger or electrostatic pen) by the capacitive method. Here, the internal signal corresponding to the second transmission signal is a spreading code capable of restoring the second transmission signal, a locally generated signal / data that matches the frequency / pattern of the second transmission signal, etc. When the demodulation process is performed digitally, correlation calculation process or discrete Fourier transform process (DFT: Discrete Fourier Transform) is performed. When the demodulation process is performed analogically, orthogonal demodulation process is performed. In addition, the dot product of the waveform of the first received signal and the waveform of the second transmitted signal does not necessarily have to be zero, but may be below a predetermined value so long as it is possible to extract a first received signal with reduced electromagnetic noise caused by the transmission of the second transmitted signal.

[0101] FIG. 8 is a waveform diagram related to the process of detecting the position pointed by the indicator. In FIG. 8, the first transmission signal 6A represents the waveform (time change) of the transmission signal (electromagnetic induction signal) related to the process of detecting the position pointed by the indicator (electronic pen 23) by the electromagnetic induction method. The first reception signal 6B represents the waveform (time change) of the reception signal (electromagnetic induction signal) related to the process of detecting the position pointed by the indicator (electronic pen 23) by the electromagnetic induction method. The second transmission signal 6C represents the waveform (time change) of the clock signal CLK1 related to the process of driving the display (display module 301). The second transmission signal 6D represents the waveform (time change) of the clock signal CLK2 related to the process of driving the display (display module 301). The first transmission signal 6E represents the waveform (time change) of the transmission signal related to the process of detecting the position pointed by the indicator (finger or electrostatic pen) by the capacitive method. The first reception signal 6F represents the waveform (time change) of the first reception signal related to the process of detecting the position pointed by the indicator (finger or electrostatic pen) by the capacitive method. The horizontal axis represents time (t) and the vertical axis represents magnitude for the first transmission signal 6A, the first reception signal 6B, the second transmission signals 6C and 6D, the first transmission signal 6E, and the first reception signal 6F. Note that the horizontal axis represents time, and all of the first transmission signal 6A, the first reception signal 6B, the second transmission signals 6C and 6D, the first transmission signal 6E, and the first reception signal 6F are shown on the same time axis.

[0102] As shown in the first transmission signal 6A, during periods D1 and D4, the control circuit 210 switches the transmission / reception switching circuit 204 to connect it to the transmission side terminal T, thereby controlling the energization of the loop coil selected by the selection circuit 201 from the X-axis direction loop coil group 22X or the Y-axis direction loop coil group 22Y, thereby transmitting a magnetic field toward the electronic pen 23.

[0103] As shown in the first reception signal 6B, in period D2, the control circuit 210 switches the transmission / reception switching circuit 204 to connect to the reception side terminal R, thereby causing each loop coil of the X-axis direction loop coil group 22X and the Y-axis direction loop coil group 22Y to receive the magnetic field transmitted from the electronic pen 23. An induced voltage is generated in each loop coil of the X-axis direction loop coil group 22X and the Y-axis direction loop coil group 22Y by the received first reception signal 6B. The first reception signal 6B received from the electronic pen 23 by each loop coil of the X-axis direction loop coil group 22X and the Y-axis direction loop coil group 22Y gradually decreases over time.

[0104] As shown in the second transmission signal 6C, in periods D1 to D4, the control circuit 34 generates a clock signal CLK1 for operating the gate driver circuit 303, and outputs the clock signal CLK1 to the gate driver circuit 303 via the clock line.

[0105] As shown in the second transmission signal 6D, in periods D1 to D4, the control circuit 34 generates a clock signal CLK2 that is out of phase with the clock signal CLK1 in order to operate the gate driver circuit 303, and outputs the clock signal CLK2 to the gate driver circuit 303 via the clock line.

[0106] As shown in the first transmission signal 6E, in periods D1 to D4, the control circuit 410 controls the transmission signal generating circuit 401 to cause the transmission signal generating circuit 401 to transmit a transmission signal via the transmission electrode selection circuit 402 to the second electrode 42Y (transmission electrode).

[0107] As shown in the first received signal 6F, in periods D1 to D4, the control circuit 410 controls the receiving electrode selection circuit 404 to receive a received signal from the first electrode 42X.

[0108] In this embodiment, during a period D11 of the period D1, the waveform of the second transmission signal 6D output from the control circuit 34 is orthogonal to the waveform of the first transmission signal 6E transmitted to the second electrode 42Y (transmission electrode). Based on the principle of detecting a position pointed to by a pointer (finger or electrostatic pen) by the capacitive method, the center frequency of the first reception signal 6F received from the first electrode 42X is the same as the center frequency of the first transmission signal 6E transmitted to the second electrode 42Y (transmission electrode), so during a reception period R1 of the first reception signal 6F, which is equal to the period D11, the waveform of the second transmission signal 6D output from the control circuit 34 is orthogonal to the waveform of the first reception signal 6F received from the first electrode 42X. In the example shown in FIG. 8, the value obtained by subtracting the wave number (1 wave) of the second transmission signal 6D output from the control circuit 34 from the wave number (3 waves) of the first transmission signal 6E transmitted to the second electrode 42Y (transmission electrode) is a positive integer (2 waves).

[0109] In this embodiment, in order to enable the first reception signal 6F to be correctly demodulated even if electromagnetic noise is mixed from the signal line (clock line) used to transmit the second transmission signal 6D to the signal line used to receive the first reception signal 6F received from the first electrode 42X during the reception period R1 of the first reception signal 6F, the second transmission signal 6D and the first transmission signal 6E are transmitted in advance in the same period D11 so as to be orthogonal to each other.

[0110] That is, as a process for receiving the first reception signal 6F, the first reception signal 6F received in the reception period R1 is multiplied by an internal signal corresponding to the second transmission signal 6D output from the control circuit 34 and integrated for a predetermined period of time. This makes it possible to extract (demodulate) the first reception signal 6F in which the inclusion of electromagnetic noise due to the transmission of the second transmission signal 6D is suppressed. In other words, it becomes possible to separate noise unrelated to the characteristics of the first reception signal 6F to be detected, and it is possible to suppress a decrease in the accuracy of detecting the position indicated by the indicator (finger or electrostatic pen) using the capacitive method.

[0111] In addition, in a period D11 of the period D1, the waveform of the second transmission signal 6C output from the control circuit 34 is orthogonal to the waveform of the first transmission signal 6A transmitted to energize and control the loop coil. Here, based on the principle of detecting the pointing position by the pointer (electronic pen 23) by the electromagnetic induction method, the center frequency of the first transmission signal 6A transmitted to energize and control the loop coil is the same as the center frequency of the first reception signal 6B received from the electronic pen 23 in the frequency spectrum, so that in a reception period R2 of the first reception signal 6B received from the electronic pen 23, the waveform of the second transmission signal 6C output from the control circuit 34 is orthogonal to the waveform of the first reception signal 6B received from the electronic pen 23. In the example shown in FIG. 8, in the same period D11, the value obtained by subtracting the wave number (1 wave) of the second transmission signal 6C output from the control circuit 34 from the wave number (6 waves) of the first transmission signal 6A transmitted to energize and control the loop coil is a positive integer (5 waves).

[0112] In this embodiment, in order to enable the first reception signal 6B to be correctly demodulated even if electromagnetic noise is mixed into the loop coils (X-axis loop coil group 22X and Y-axis loop coil group 22Y) used to receive the first reception signal 6B from the electronic pen 23 during the reception period R2 of the first reception signal 6B, the second transmission signal 6C and the first transmission signal 6A are transmitted in advance in the same period D11, the signals being orthogonal to each other.

[0113] That is, as a process for receiving the first reception signal 6B, the first reception signal 6B received in the reception period R2 is multiplied by an internal signal corresponding to the second transmission signal 6C output from the control circuit 34 and integrated for a predetermined period of time. This makes it possible to extract (demodulate) the first reception signal 6B in which the inclusion of electromagnetic noise due to the transmission of the second transmission signal 6C is suppressed. In other words, it becomes possible to separate noise unrelated to the characteristics of the first reception signal 6B to be detected, and it is possible to suppress a decrease in the accuracy of detecting the position indicated by the pointer (electronic pen 23) by the electromagnetic induction method.

[0114] (Modification) In the above embodiment, an example has been described in which, when the waveform of the first transmission signal and the waveform of the second transmission signal are orthogonal to each other, the value obtained by subtracting the wave number of the second transmission signal from the wave number of the first transmission signal is a positive or negative integer, but the present invention is not limited to this. For example, when the waveform of the first transmission signal and the waveform of the second transmission signal are orthogonal to each other, the inner product of the waveform of the first transmission signal and the waveform of the second transmission signal may be 0, and the value obtained by subtracting the wave number of the second transmission signal from the wave number of the first transmission signal may be 0. In this case, the first transmission signal may be a sine wave (e.g., sin(2πmx)), which is a sine wave, and the second transmission signal may be a cosine wave (e.g., cos(2πnx), m=n), which is a sine wave. Since the phase of the signal transmitted by the electromagnetic induction pen is unknown on the side of the first receiving unit that receives the electromagnetic induction signal, it may be difficult to distinguish between the first transmission signal and the second transmission signal when they are waveforms with the same frequency but with different phases (e.g., sine wave and cosine wave). Therefore, when the first processing is of the electromagnetic induction type, it is preferable that the value obtained by subtracting the wave number of the second transmission signal from the wave number of the first transmission signal during the same period is a positive or negative integer.

[0115] In the above embodiment, the electronic device 10 may employ an in-cell system. The in-cell system is a system in which the display device 30 and the first electrode 42X or the second electrode 42Y of the second sensor 40 for capacitive position detection are also used as electrodes (for example, a common electrode of a liquid crystal display, a negative electrode of an organic EL display) to which a potential required for driving the display pixels 32 of the display device 30 is supplied.

[0116] In addition, the above-mentioned embodiments are merely examples of the embodiment of the present invention, and the technical scope of the present invention should not be interpreted as being limited by these. In other words, the present invention can be embodied in various forms without departing from the gist or main characteristics of the present invention. [Explanation of symbols]

[0117] 10: electronic device, 20: first sensor, 21: wiring board, 23: electronic pen, 23L: coil, 23C: capacitor, 22X: X-axis direction loop coil group, 22X1: loop coil, 22Y: Y-axis direction loop coil group, 22Y1: loop coil, 30: display device, 31: display board, 32: display pixel, 33: display screen, 34: control circuit, 40: second sensor, 41: transparent board, 42X: first electrode, 42X1: signal line, 42Y: second electrode, 42Y1: signal line, 50: control circuit board, 60: planar member, 60a: surface, 61: area, 62: frame area, 70: housing, 71: recess, 72: frame area, 100: indicator, 101: position detection circuit, 200: position detection circuit, 201: selection circuit, 202: oscillator, 203: current driver, 204: transmission / reception switching circuit, 205: reception amplifier, 206: detection circuit, 207: low-pass filter, 208: sample-and-hold circuit, 209: A / D conversion circuit, 210: control circuit, 301: display module, 302: backlight module, 303: gate driver circuit, 304: source driver circuit, 400: position detection circuit, 401: transmission signal generation circuit, 402: transmission electrode selection circuit, 404: reception electrode selection circuit, 405: reception signal processing circuit, 406 position information output circuit, 410: control circuit, 411: position indication status determination circuit

Claims

1. An indication position detection device for detecting an indication position by an indicator, A first transmitting unit and a second transmitting unit, The first transmission unit transmits a first transmission signal related to a first process of detecting a position pointed to by a pointer, the second transmission unit transmits a second transmission signal associated with a second process different from the first process; During the same period, the waveform of the first transmission signal and the waveform of the second transmission signal are orthogonal to each other, the first process is a process of detecting a position pointed to by a pointer by an electromagnetic induction method, The second process is a process of detecting a position pointed to by a pointer using a capacitive method. Pointing position detection device.

2. 2. The pointing position detection device according to claim 1, In the same period, a value obtained by subtracting the wave number of the second transmission signal from the wave number of the first transmission signal is a positive or negative integer. Pointing position detection device.

3. 2. The pointing position detection device according to claim 1, A transmission period of the first transmission signal overlaps with at least a portion of a transmission period of the second transmission signal. Pointing position detection device.

4. The indication position detection device according to claim 3, The start and end points of the transmission period of the first transmission signal are the same as the start and end points of the transmission period of the second transmission signal. Pointing position detection device.

5. An indication position detection device for detecting an indication position by an indicator, A first transmitting unit, a second transmitting unit, and a display, The first transmission unit transmits a first transmission signal related to a first process of detecting a position pointed to by a pointer, the second transmission unit transmits a second transmission signal associated with a second process different from the first process; During the same period, the waveform of the first transmission signal and the waveform of the second transmission signal are orthogonal to each other, the first process is a process of detecting a position pointed to on the display by a pointer using an electromagnetic induction method; the second process is a process of driving the display; Pointing position detection device.

6. An indication position detection device for detecting an indication position by an indicator, A first transmitting unit, a second transmitting unit, and a display, The first transmission unit transmits a first transmission signal related to a first process of detecting a position pointed to by a pointer, the second transmission unit transmits a second transmission signal associated with a second process different from the first process; During the same period, the waveform of the first transmission signal and the waveform of the second transmission signal are orthogonal to each other, the first process is a process of detecting a position pointed to on the display by a pointer using a capacitive touch; the second process is a process of driving the display; Pointing position detection device.

7. An indication position detection device for detecting an indication position by an indicator, A first transmitting unit, a second transmitting unit, a first receiving unit, and a second receiving unit, The first transmission unit transmits a first transmission signal related to a first process of detecting a position pointed to by a pointer, The second transmission unit transmits a second transmission signal related to a second process of detecting a position pointed to by a pointer, The first receiving unit receives a first received signal related to the first processing; The second receiving unit receives a second received signal related to the second processing; In the same period, the waveform of the first received signal and the waveform of the second received signal are orthogonal to each other. Pointing position detection device.

8. The indication position detection device according to claim 7, During the same period, a value obtained by subtracting the wave number of the second received signal from the wave number of the first received signal is a positive or negative integer. Pointing position detection device.

9. The indication position detection device according to claim 7, The first receiving unit receives the first reception signal during a transmission period of the second transmission signal. Pointing position detection device.

10. The indication position detection device according to claim 7, The second receiving unit receives the second reception signal during a transmission period of the first transmission signal. Pointing position detection device.

11. The indication position detection device according to claim 7, A guard interval is provided between a reception period of the first reception signal and a reception period of the second reception signal. Pointing position detection device.

12. A method for detecting a position pointed to by a pointer, comprising the steps of: Transmitting a first transmission signal related to a first process of detecting a position pointed to by a pointer; Transmitting a second transmission signal related to a second process of detecting a position pointed to by the pointer; receiving a first received signal associated with the first process; receiving a second received signal associated with the second process; Including, In the same period, the waveform of the first received signal and the waveform of the second received signal are orthogonal to each other. Pointing position detection method.

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