Indicated position detecting device and indicated position detecting method

Abstract

To provide an indicated position detecting device and an indicated position detecting method, capable of suppressing a decrease in the detection accuracy of an indicated position by an indicator.SOLUTION: An indicated position detection device, which detects an indicated position 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 indicated position by the indicator. The second transmission unit transmits a second transmission signal related to second processing different from the first processing. The waveform of the first transmission signal is orthogonal to the waveform of the second transmission signal in the same period.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to an indication position detection device and an indication position detection method.

Background Art

[0002] In an electronic device such as a tablet-type information terminal equipped with a flat display (for example, a liquid crystal panel), an indication position detection device that detects a position (indication position) indicated by an indicator such as a finger or a pen is mounted and widely used. As position detection methods used in the indication position detection device, various methods such as a resistive film method, an electromagnetic induction method, and a capacitance method are provided.

[0003] Among these, an indication position detection device using the electromagnetic induction method includes, for example, as disclosed in Patent Document 1, a position detection device including a sensor in which a large number of loop coils are arranged in the X-axis direction and the Y-axis direction of the coordinate axes, and an electronic pen as a pen-shaped position indicator having a resonance circuit including a coil as an example of an inductance element wound around a magnetic core and a capacitor.

[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 resonance circuit of the electronic pen is configured to have a resonance frequency corresponding to the frequency of the transmission signal, and stores magnetic energy based on the electromagnetic induction action between the loop coil of the sensor. Then, the electronic pen feeds back a magnetic field based on the magnetic energy stored in the resonance circuit to the loop coil of the sensor of the position detection device.

[0005] An induced voltage is generated in the loop coil of the sensor by the magnetic field from this electronic pen. The position detection device detects the coordinate values in the X-axis direction and the Y-axis direction of the position on the sensor indicated by the electronic pen based on the values of the induced voltages generated in each loop coil.

[0006] An electromagnetic induction type indication position detection device can input an indication position with relatively high precision using an electronic pen as an indicator, and is widely used.

[0007] In addition, for a capacitance type indication position detection device, which is a detection method for the indication position of an indicator (finger, pen-type position indicator (electrostatic pen), etc.) used for a touch panel or the like, there are two types of methods: a surface type (Surface Capacitive Type) and a projected type (Projected Capacitive Type). Both methods detect a change in the electrostatic coupling state between the sensor electrode and the indicator to detect the indication position of the indicator. An indication position detection device of a method called a cross-point electrostatic coupling method, which is a development of the projected capacitance method, is also widespread (for example, see Patent Document 2).

[0008] FIG. 9 shows a configuration example of a sensor of an indication position detection device of the cross-point capacitance method. As shown in FIG. 9, the sensor of the indication position detection device of the cross-point capacitance method 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 an indication input surface at a predetermined interval in the X-axis direction and the Y-axis direction, respectively, so that they are orthogonal to each other and arranged with a slight gap therebetween. In this case, a predetermined capacitance Co (fixed capacitance) is formed at the overlapping portion (cross-point) between the upper electrode Ex and the lower electrode Ey.

[0009] When an indicator 100 such as a position indicator held by a user or the finger of the user approaches or contacts the indication input surface, a capacitance Cf is formed between the electrodes Ex and Ey at that position and the indicator. The indicator 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 indicated by the indicator 100. In the cross-point capacitance type position detection device, the position indicated by the indicator 100 within the indication input surface is specified by detecting this change in capacitance.

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

[0011] The indicator for which the sensor for detecting the indicated position of the electromagnetic induction method described above detects the indicated position is an electromagnetic induction type electronic pen. On the other hand, the indicator for which the sensor for detecting the indicated position of the capacitance method detects the indicated position is a finger or a capacitive pen, and the objects to be detected are completely different. Therefore, it is conceivable to mount a sensor for detecting the indicated position of the electromagnetic induction method and a sensor for detecting the indicated position of the capacitance method on one indicated position detection device. According to this indicated position detection device, for example, while detecting the indication of the indicated position by a finger using the sensor for detecting the indicated position of the capacitance method, at the same time, it is possible to detect the indication of the indicated position by an electronic pen using the sensor for detecting the indicated position of the electromagnetic induction method.

Prior Art Documents

Patent Documents

[0012]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0013] By the way, in an electronic device such as a tablet-type information terminal equipped with a display (e.g., a liquid crystal panel), in order to miniaturize the electronic device while maintaining the size of the display panel, it has become an issue to respond to a narrower frame (border) that surrounds the display panel. And, in order to respond to the narrower frame, in the electronic device, it is required to reduce the arrangement space of the loop coil and the signal line used for the indication position detection device.

[0014] However, when an electromagnetic induction type indication position detection device and a capacitance type indication position detection device are mounted on one electronic device, the loop coil used for the electromagnetic induction type indication position detection device and the signal line used for transmitting a transmission signal and receiving a reception signal in the capacitance type indication position detection device may be arranged close to each other. In this case, due to magnetic coupling (interference) between the loop coil and the signal line, electromagnetic noise may be mixed from the signal line used for transmitting the transmission signal into the loop coil, or electromagnetic noise may be mixed from the loop coil into the signal line used for receiving the reception signal. When electromagnetic noise is mixed from the signal line used for transmitting the transmission signal into the loop coil, 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 indication position in the electromagnetic induction type indication position detection device decreases. Also, when electromagnetic noise is mixed from the loop coil into the signal line used for receiving the reception signal, the S / N ratio of the reception signal decreases, and the detection accuracy of the indication position in the capacitance type indication position detection device decreases.

[0015] In addition, when an electromagnetic induction type indication position detection device and a capacitance type indication position detection device are mounted on one electronic device, a loop coil used for the electromagnetic induction type indication position detection device, a signal line used for the capacitance type indication position detection device, and a signal line (for example, a clock line) used for transmitting a drive signal (for example, a clock signal) for driving a display panel may be arranged in proximity to each other. In this case, electromagnetic noise may be mixed from the signal line used for transmitting the drive signal into the loop coil used for the electromagnetic induction type indication position detection device and the signal line used for receiving a reception signal in the capacitance type indication position detection device. As a result, the S / N ratio of the magnetic field transmitted from the electronic pen and received by the loop coil decreases, the position detection accuracy in the electromagnetic induction type indication position detection device decreases, or the S / N ratio of the reception signal decreases, and the position detection accuracy in the capacitance type indication position detection device decreases.

[0016] An object of the present invention is to provide an indication position detection device and an indication position detection method capable of suppressing a decrease in detection accuracy of an indication position by an indicator.

Means for Solving the Problems

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

[0018] According to the present invention, in the same period, the waveform of the first transmission signal and the waveform of the second transmission signal are orthogonal to each other, noise mixed into the reception signal related to the first or second process by the first or second transmission signal is suppressed, and a decrease in the position detection accuracy of the first or second process related to the reception signal is suppressed.

[0019] Hereinafter, various embodiments of the present invention will be exemplified. The embodiments shown below can be combined with each other. The indication position detection device according to [2][1], wherein, 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. The indication position detection device according to [3][1] or [2], wherein the first process is a process of detecting an indication position by an indicator by an electromagnetic induction method, and the second process is a process of detecting an indication position by an indicator by a capacitance method. The indication position detection device according to any one of [4][1] to [3], wherein a transmission period of the first transmission signal overlaps at least a part of a transmission period of the second transmission signal. The indication position detection device according to [5][4], wherein a start time point and an end time point of a transmission period of the first transmission signal are the same as a start time point and an end time point of a transmission period of the second transmission signal. The indication position detection device according to [6][1], further including a display, wherein the first process is a process of detecting an indication position on the display by an indicator by an electromagnetic induction method, and the second process is a process of driving the display. The indication position detection device according to [7][1], further including a display, wherein the first process is a process of detecting an indication position on the display by an indicator by a capacitance method, and the second process is a process of driving the display. [8]An indication position detection device that detects an indication position by an indicator, comprising a first transmission unit, a second transmission unit, a first reception unit, and a second reception unit, wherein the first transmission unit transmits a first transmission signal related to a first process for detecting an indication position by an indicator, the second transmission unit transmits a second transmission signal related to a second process for detecting an indication position by an indicator, the first reception unit receives a first reception signal related to the first process, the second reception unit receives a second reception signal related to the second process, and in the same period, the waveform of the first reception signal and the waveform of the second reception signal are orthogonal. An indication position detection device. [9]The indication position detection device according to [8], wherein in the same period, 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. An indication position detection device.

[10] The indication position detection device according to [8] or [9], wherein the first reception unit receives the first reception signal during the transmission period of the second transmission signal. An indication position detection device.

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

[10] , wherein the second reception unit receives the second reception signal during the transmission period of the first transmission signal. An indication position detection device.

[12] The indication position detection device according to any one of [8] to

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

[13] An indication position detection method for detecting an indication position by an indicator, comprising the steps of transmitting a first transmission signal related to a first process for detecting an indication position by an indicator and transmitting a second transmission signal related to a second process different from the first process, and in the same period, the waveforms of the first transmission signal and the second transmission signal are orthogonal. An indication position detection method.

[14] An indication position detection method for detecting an indication position by an indicator, the method including: transmitting a first transmission signal related to a first process for detecting an indication position by the indicator; transmitting a second transmission signal related to a second process for detecting an indication position by the indicator; receiving a first reception signal related to the first process; and receiving a second reception signal related to the second process, wherein in the same period, the waveform of the first reception signal and the waveform of the second reception signal are orthogonal.

Advantages of the Invention

[0020] According to the present invention, it is possible to suppress a decrease in the detection accuracy of an indication position by an indicator.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0022] Embodiments of the present invention will be described with reference to the accompanying drawings. In each figure, those with the same reference numerals have the same or similar configurations.

[0023] (Description of the overall configuration) FIG. 1 is an exploded configuration diagram showing a configuration example of an electronic device 10 (corresponding to the "instruction position detection device" of the present invention) in the present embodiment. The electronic device 10 has a function of detecting a position indicated by an indicator for electromagnetic induction (hereinafter referred to as the "first indicator"), such as an electronic pen, by a sensor for detecting an instruction position of the electromagnetic induction method (hereinafter referred to as the "first sensor"), and also has a function of detecting a position indicated by an indicator (hereinafter referred to as the "second indicator"), such as a finger or a position indicator (capacitive pen), on the display screen of the display device by a sensor for detecting an instruction position of the capacitive method (hereinafter referred to as the "second sensor"). It is a pad-type terminal capable of simultaneously detecting the instruction positions by the first and second indicators with both sensors.

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

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

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

[0027] The detection area of the first sensor 20 capable of detecting the position indicated by the first indicator, the detection area of the second sensor 40 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 set to be approximately the same size and are arranged in an overlapping relationship.

[0028] In FIG. 1, although not shown, 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 the 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 mounted with a microcomputer for controlling the electronic device 10, a control circuit of the display device 30, other electronic components, and a copper foil wiring pattern. Note that there may be a plurality of control circuit boards 50 in the electronic device 10. Further, the first and second position detection circuits may be provided on a control circuit board different 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 side thereof is an indication surface (operation surface) for indicating the position by the first indicator made of an electronic pen and the second indicator such as a finger or an indication pen. The second sensor 40 and the display device 30 are arranged on the side of the surface opposite to the one surface 60a of the planar member 60.

[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 of FIG. 1, the area 61 indicated by the dotted line is the 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 by performing, for example, silk screen printing on the frame area 62 to make the frame area 62 opaque and keeping only the area 61 transparent.

[0031] The housing 70 is made of, for example, synthetic resin. A recess 71 for housing the first sensor 20, the display device 30, the second sensor 40, and the control circuit board 50 is formed in the housing 70. After the first sensor 20, the display device 30, the second sensor 40, and the control circuit board 50 are housed in this recess 71, the frame region 62 of the planar member 60 is coupled 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] Note that the first sensor 20 may be inserted into 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, with reference to FIG. 2, a configuration example of the first sensor 20 and the position detection circuit 200 of the electromagnetic induction method will be described. An electronic pen 23, which is an example of the first indicator used together with the first sensor 20 in this example, incorporates a resonance circuit composed of a coil 23L and a capacitor 23C connected in parallel to the coil 23L.

[0034] The first sensor 20 is configured such that an X-axis direction loop coil group 22X is disposed on one surface of a wiring board 21 (see FIG. 1), and a Y-axis direction loop coil group 22Y is disposed 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 the present embodiment, n loop coils are disposed in the X-axis direction and m loop coils are disposed in the Y-axis direction. Each loop coil of the X-axis direction loop coil group 22X and the Y-axis direction loop coil group 22Y is disposed so as to overlap with each other.

[0035] Each loop coil constituting the X-axis direction loop coil group 22X is arranged at equal intervals in the horizontal direction (X-axis direction) of the detection area for detecting the instructed position by the electronic pen 23 so as to be sequentially overlapped. Further, each loop coil constituting the Y-axis direction loop coil group 22Y is arranged at equal intervals in the vertical direction (Y-axis direction) of the detection area so as to be sequentially overlapped.

[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 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 the selection circuit 201. The selection circuit 201 sequentially selects one loop coil from the two loop coil groups 22X and 22Y according to the control of the control circuit 210.

[0038] The oscillator 202 generates an AC signal with a frequency f0. This AC signal is supplied to the current driver 203, converted into a current, and then sent to the transmission / reception switching circuit 204. 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 under the control of the control circuit 210. The current driver 203 is connected to the transmission side terminal T, and the reception amplifier 205 is connected to the reception side terminal R, respectively.

[0039] Therefore, at the time of transmission, the alternating current signal converted into current in 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. Also, at the time of reception, the induced voltage generated in the loop coil selected by the selection circuit 201 is supplied to the reception amplifier 205 via the reception-side terminal R of the selection circuit 201 and the transmission / reception switching circuit 204, amplified, and sent to the detection circuit 206.

[0040] The induced voltage amplified by the reception amplifier 205 is detected by the detection circuit 206 and supplied to the A / D conversion circuit 209 via the low-pass filter 207 and the sample-and-hold circuit 208. The A / D conversion circuit 209 converts the signal supplied via the low-pass filter 207 and the sample-and-hold circuit 208 from an analog signal into a digital signal and supplies it to the 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 to the transmission-side terminal T, thereby performing energization control on the loop coil selected by the selection circuit 201 among the X-axis direction loop coil group 22X or the Y-axis direction loop coil group 22Y to send out a magnetic field. The resonance circuit of the electronic pen 23 receives the magnetic field sent out from this loop coil, stores magnetic energy, and acts to send out 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 to the reception-side terminal R. Then, 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 magnetic field transmitted from the electronic pen 23 which is a position indicator.

[0044] The control circuit 210 calculates the coordinate values of the indicated positions in the X-axis direction and the Y-axis direction in the detection area of the first sensor 20 based on the voltage values of the induced voltages generated in each of these loop coils. 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 has received the detection result from the control circuit 210 controls the screen to be displayed on the display device 30.

[0045] Also, the control circuit 210 is connected to the control circuit 410 of the position detection circuit 400 of the second sensor 40, and exchanges synchronization signals with the control circuit 410 to synchronize the detection operation of the indicated position by the electronic pen and the detection operation of the indicated position by a finger or a position indicator. For example, the control circuit 210 transmits a start signal indicating the start of the detection operation of the indicated position by the electronic pen to the control circuit 410. Also, the control circuit 410 may transmit a start signal indicating the start of the detection operation of the indicated position by a finger or a position indicator to the control circuit 210. Separately 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 indicated position by the electronic pen and the detection operation of the indicated position by a finger or a position indicator.

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

[0047] The second sensor 40 is configured such that, for example, an electrode group composed of a plurality of electrodes having light transmissivity is formed on one surface of the transparent substrate 41 (the surface opposite to the surface facing the display screen 33 of the display device 30). The transparent substrate 41 is made of, for example, a glass substrate or a resin film substrate.

[0048] The electrode group consists 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) orthogonal to the Y-axis direction. The first electrodes 42X are arranged at predetermined intervals in the X-axis direction. Also, the second electrodes 42Y are arranged at predetermined intervals in the Y-axis direction. These first electrodes 42X and second electrodes 42Y are made of a light-transmissive conductive material, such as a conductor made of an ITO film or a metal mesh.

[0049] And the first electrode 42X and the second electrode 42Y are formed on the same side of the transparent substrate 41. For this reason, in the region of the cross point which is the intersection of the first electrode 42X and the second electrode 42Y orthogonal to each other, an insulating material is arranged between the first electrode 42X and the second electrode 42Y so that they 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] Based on the control of the control circuit 410, the position detection circuit 400 discretely executes position detection processing at predetermined time intervals, for example, every 10 msec, to individually detect a plurality of position indications by the second indicator on the second sensor 40 and obtain respective position detection results.

[0052] The transmission signal generation circuit 401 and the transmission electrode selection circuit 402 constitute a transmission signal supply circuit, and the reception electrode selection circuit 404 and the reception signal processing circuit 405 constitute a signal reception circuit. And the first electrode 42X is used as a reception electrode, and the second electrode 42Y is used as a transmission electrode.

[0053] The transmission signal generation 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 (see, for example, Japanese Unexamined Patent Application Publication No. 2021-99827).

[0054] The transmission electrode selection circuit 402 selects a predetermined second electrode 42Y (transmission electrode) according to the selection control of the control circuit 410. The transmission signal from the transmission signal generation circuit 401 is simultaneously supplied to a plurality of (all, even-numbered or odd-numbered) second electrodes 42Y selected by the transmission electrode selection circuit 402. Note that, without providing the transmission electrode selection circuit 402, the transmission signal may be directly transmitted from the transmission signal generation circuit 401 to all the second electrodes 42Y.

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

[0056] Based on the control by the control circuit 410, the reception signal processing circuit 405 detects a signal change of the reception signal generated by a second indicator such as a finger or a position indicator indicating a position on the second sensor 40 with 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, as a coordinate output which is an indication position detection signal corresponding to the position indicated by a second indicator such as a finger or a position indicator, from the detection output of the reception signal processing circuit 405, the first electrode 42X where the signal change of the reception signal has occurred and the second electrode 42Y to which the transmission signal is being supplied at that time, and outputs the generated coordinate output to the control circuit 410 as a position detection result.

[0058] An external host (PC) that receives the position detection result from the position information output circuit 406 controls the screen displayed on the display device 30 according to the position detection result.

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

[0060] Next, with reference to FIG. 4, a control configuration example of the display device 30 will be described. 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 a 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 (pixel elements) arranged at intersections of the row signal lines GL1 to GLn and the column signal lines SL1 to SLm. The display module 301 drives any one of the corresponding row signal lines GL1 to GLn according to the gate signals VG1 to VGn transmitted from the 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 the source driver circuit 304.

[0062] The row signal lines GL1 to GLn are, for example, gate lines, and are arranged in n numbers 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 the gate driver circuit 303, and relay the charge transfer between the gate electrode of the display pixel 32 at the intersection 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 are arranged in m numbers 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 the source driver circuit 304, and relay the charge transfer between the source electrode of the display pixel 32 at the intersection with the row signal lines GL1 to GLn and the source driver circuit 304.

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

[0065] The backlight module 302 is a light source arranged on the back side of the display module 301, and irradiates light from the back side to the display module 301.

[0066] The gate driver circuit 303 is a circuit that drives the row signal lines GL1 to GLn, and is arranged in 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 order by outputting the gate signals VG1 to VGn to the corresponding row signal lines GL1 to GLn at a timing according to the clock signals CLK1 to CLK4 output from the control circuit 34. Further, the gate driver circuit 303 supplies and extracts 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 that drives the column signal lines SL1 to SLm, and is arranged below the display module 301 when the display device 30 is viewed from the display screen 33 side. The source driver circuit 304 outputs the 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 a timing according to the control circuit 34. The source driver circuit 304 supplies the potential of the source signals VS1 to VSm corresponding to the display pixel 32 to the source electrode of the display pixel 32 corresponding to the intersection 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 starting to drive the row signal lines GL1 to GLm by the gate driver circuit 303, 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. Further, the control circuit 34 generates the 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] Further, 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. Also, the control circuit 34 sets the 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 on the set potential to the source driver circuit 304.

[0070] (Description of the problem) In the above-described electronic device 10, in order to miniaturize the electronic device 10 while maintaining the size of the flat display (display module 301), it is an issue to cope with the reduction of the width of the frame (outer frame) surrounding the flat display (display module 301). And, in order to cope with the reduction of the outer frame, in the electronic device 10, it is required to reduce the arrangement space of the loop coil and the signal line used in the indication position detection device that detects the indication position by the indicator.

[0071] However, when both an electromagnetic induction type indication position detection device and a capacitance type indication position detection device are mounted on one electronic device 10, the loop coil used in the electromagnetic induction type indication position detection device and the signal line used for transmitting the transmission signal and receiving the reception signal in the capacitance type indication position detection device may be arranged close to each other. In this case, due to magnetic coupling (interference) between the loop coil and the signal line, electromagnetic noise may be mixed from the signal line used for transmitting the transmission signal into the loop coil, or electromagnetic noise may be mixed from the loop coil into the signal line used for receiving the reception signal. When electromagnetic noise is mixed from the signal line used for transmitting the transmission signal into the loop coil, 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 indication position in the electromagnetic induction type indication position detection device decreases. Also, when electromagnetic noise is mixed from the loop coil into the signal line used for receiving the reception signal, the S / N ratio of the reception signal decreases, and the detection accuracy of the indication position in the capacitance type indication position detection device decreases.

[0072] For example, as shown in FIG. 5, there may be a case where the loop coils 22X1 and 22Y1 used in the electromagnetic induction type indication position detection device and the signal lines 42X1 used for transmitting the transmission signal and the signal lines 42Y1 used for receiving the reception signal in the capacitance type indication position detection device are arranged close to each other. In this case, due to the magnetic coupling (interference) between the loop coil 22X1 and the signal line 42X1, electromagnetic noise is mixed from the signal line 42X1 used for transmitting the transmission signal into the loop coil 22X1, transmitted from the electronic pen 23, and received by the loop coil 22X1, resulting in a decrease in the S / N ratio of the magnetic field, and a decrease in the detection accuracy of the indication position in the electromagnetic induction type indication position detection device. Also, due to the magnetic coupling (interference) between the loop coil 22Y1 and the signal line 42Y1, electromagnetic noise is mixed from the loop coil 22Y1 into the signal line 42Y1 used for receiving the reception signal, resulting in a decrease in the S / N ratio of the reception signal, and a decrease in the detection accuracy of the indication position in the capacitance type indication position detection device.

[0073] Also, when an electromagnetic induction type indication position detection device and a capacitance type indication position detection device are mounted on a single electronic device 10, there may be a case where the loop coil used in the electromagnetic induction type indication position detection device, the signal line used in the capacitance type indication position detection device, and the signal line (for example, clock line) used for transmitting the drive signal (for example, clock signal) for driving the flat display (display module 301) are arranged close to each other. In this case, as a result of electromagnetic noise being mixed from the signal line used for transmitting the drive signal into the loop coil used in the electromagnetic induction type indication position detection device and the signal line used for receiving the reception signal in the capacitance type indication position detection device, the S / N ratio of the magnetic field transmitted from the electronic pen 23 and received by the loop coil decreases, the accuracy of position detection in the electromagnetic induction type indication position detection device decreases, or the S / N ratio of the reception signal decreases, and the accuracy of position detection in the capacitance type indication position detection device decreases.

[0074] For example, as shown in FIG. 6, there may be a case where a loop coil (not shown) used in an electromagnetic induction type indication position detection device, a signal line (not shown) used in a capacitance type indication position detection device, and a signal line (clock line) used for transmitting drive signals (clock signals CLK1 to CLK4) for driving a flat display (display module 301) are arranged in proximity to each other. In this case, as a result of electromagnetic noise being mixed from the clock line used for transmitting the clock signal into the loop coil used in the electromagnetic induction type indication position detection device or the signal line used for receiving a received signal in the capacitance type indication position detection device, the S / N ratio of the magnetic field transmitted from the electronic pen 23 and received by the loop coil decreases, the accuracy of position detection in the electromagnetic induction type indication position detection device decreases, or the S / N ratio of the received signal decreases, and the accuracy of position detection in the capacitance type indication position detection device decreases.

[0075] (Description of the configuration for solving the problem) In order to solve the above-described problems, the electronic device 10 (indicating position detection device) in the present embodiment includes a first transmission 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 an indicating position by an indicator (electronic pen 23) by an electromagnetic induction method, a second transmission unit (transmission signal generation circuit 401) that transmits a second transmission signal (transmission signal) related to a second process of detecting an indicating position by an indicator (finger or position indicator (capacitive pen)) by a capacitance method, and a first reception 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. And, during 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. Here, based on the principle of detecting the indicating position by the indicator (electronic pen 23) by the electromagnetic induction method, in the frequency spectrum represented by the amplitude of each sine wave frequency component as a function of frequency, 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. Therefore, 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. As a result, a first reception signal in which the mixing of electromagnetic noise due to the transmission of the second transmission signal is suppressed can be detected. 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. Note that in the frequency spectrum, at the center frequency of the first reception signal (electromagnetic induction signal), the signal power of the second transmission signal (transmission signal) is 0.

[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), the first transmission signal (electromagnetic induction signal) and the second transmission signal (transmission signal) are transmitted in advance during the same period so that the second reception signal can 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).

[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 received signal 5B, during period D2, the control circuit 210 switches to connect the transceiver switch circuit 204 to the receiving terminal R, 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 received signal 5B. The first received signal 5B received 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 the electromagnetic energy 5C, during period D1, a magnetic field is sent from the loop coil controlled for energization by the transmission of the first transmission signal 5A (electromagnetic induction signal) toward the electronic pen 23, and thus the magnetic energy stored in the resonance circuit of the electronic pen 23 gradually increases. Then, during periods D2 and D3 when the transmission of the magnetic field from the loop coil toward the electronic pen 23 stops, as the first received signal 5B (electromagnetic induction signal) is transmitted from the electronic pen 23 to each loop coil of the X-axis direction loop coil group 22X and the Y-axis direction loop coil group 22Y, the electromagnetic energy stored in the resonance circuit of the electronic pen 23 gradually decreases.

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

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

[0087] In the present embodiment, in period D11 within period D1, the waveform of the first transmission signal 5A transmitted to control the 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 the indicated position by an indicator (finger or position indicator (electrostatic pen)) by the capacitance method, since the center frequency of the second received signal 5E received from the first electrode 42X in the frequency spectrum is the same as the center frequency of the second transmission signal 5D transmitted to the second electrode 42Y (transmission electrode), in the reception period R1 of the second received signal 5E equal to period D11, the waveform of the first transmission signal 5A transmitted to control the energization of the loop coil is orthogonal to the waveform of the second received signal 5E received from the first electrode 42X. In the example shown in FIG. 7, in the same period D11, 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 is a positive integer (3 waves). In the present embodiment, by adjusting the phase of the second transmission signal 5D transmitted to the second electrode 42Y (transmission electrode) (for example, shifting it by 90 degrees), the steep change of the second transmission signal 5D at the start and end points of period D11 is avoided, and when a deviation in the transmission timing of the second transmission signal 5D occurs, the 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) is suppressed from decreasing.

[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] Note that a period G corresponding to a guard interval is provided between a reception period R1 during which a second reception signal 5E from the first electrode 42X is received and a reception period R2 of a first reception signal 5B (electromagnetic induction signal) received from the electronic pen 23. Thereby, an effect of mitigating an adverse influence (a decrease in detection accuracy of the first reception signal 5B and the second reception signal 5E and thus a decrease in detection accuracy of the indicated position) when a deviation in timing of receiving the second reception signal 5E from the first electrode 42X or a deviation in timing of receiving the first reception signal 5B from the electronic pen 23 occurs, an effect of ensuring a 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 energization of the loop coil can be obtained, and when the second transmission signal 5D transmitted to the second electrode 42Y (transmission electrode) is a spreading code and the spreading code is switched, for example, from minus (-) to plus (+) between the reception period R1 and the reception period R2 (see FIG. 7), it is also 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] Also, in this embodiment, the electronic device 10 (indicating position detection device) includes a first transmission 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 an indicating position by an indicator (electronic pen 23) using an electromagnetic induction method, a second transmission 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 reception 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. And during the same period, the waveform of the first transmission signal and the waveform of the second transmission signal are orthogonal. Here, based on the principle of detecting the indicating position by the indicator (electronic pen 23) using the electromagnetic induction method, since the center frequency of the first reception signal and the center frequency of the first transmission signal are the same in the frequency spectrum, during the reception period of the first reception signal, the waveform of the first reception signal and the waveform of the second transmission 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. As a result, it is possible to detect a first reception signal in which the mixing 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, at the center frequency of the first reception signal, the signal power density of the second transmission signal is 0.

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

[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 processing at the time of receiving the first received signal, by performing processing of multiplying the first received signal and an internal signal corresponding to the second transmission signal (clock signal) and integrating for a predetermined period, a first received signal with electromagnetic noise mixing suppressed by transmission of the second transmission signal is extracted (demodulated). In other words, it becomes possible to separate noise irrelevant to the characteristics of the first received signal to be detected, and it is possible to suppress a decrease in the accuracy of detecting an indication position by an indicator (finger or electrostatic pen) by the capacitance 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, etc. that match the frequency and pattern of the second transmission signal. When performing digital demodulation processing, correlation operation processing or discrete Fourier transform processing (DFT: Discrete Fourier Transform) is performed. When performing analog demodulation processing, quadrature demodulation processing is performed. Note that the inner product of the waveform of the first received signal and the waveform of the second transmission signal does not necessarily have to be 0, and it may be below a predetermined value to such an extent that it is possible to extract a first received signal with electromagnetic noise mixing suppressed by transmission of the second transmission signal.

[0101] FIG. 8 is a waveform diagram related to the process of detecting an indication position by an indicator. In FIG. 8, the first transmission signal 6A represents the waveform (temporal change) of a transmission signal (electromagnetic induction signal) related to the process of detecting an indication position by an indicator (electronic pen 23) using the electromagnetic induction method. The first reception signal 6B represents the waveform (temporal change) of a reception signal (electromagnetic induction signal) related to the process of detecting an indication position by an indicator (electronic pen 23) using the electromagnetic induction method. The second transmission signal 6C represents the waveform (temporal change) of a clock signal CLK1 related to the process of driving a display (display module 301). The second transmission signal 6D represents the waveform (temporal change) of a clock signal CLK2 related to the process of driving a display (display module 301). The first transmission signal 6E represents the waveform (temporal change) of a transmission signal related to the process of detecting an indication position by an indicator (finger or capacitive pen) using the capacitance method. The first reception signal 6F represents the waveform (temporal change) of a first reception signal related to the process of detecting an indication position by an indicator (finger or capacitive pen) using the capacitance method. For the first transmission signal 6A, the first reception signal 6B, the second transmission signals 6C and 6D, and the first transmission signal 6E and the first reception signal 6F, the horizontal axis represents time (t), and the vertical axis represents magnitude. Note that for the time on the horizontal axis, all of the first transmission signal 6A, the first reception signal 6B, the second transmission signals 6C and 6D, and 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, in periods D1 and D4, the control circuit 210 switches the transmission / reception switching circuit 204 to be connected to the transmission-side terminal T, thereby controlling the energization of the loop coil selected by the selection circuit 201 among the X-axis direction loop coil group 22X or the Y-axis direction loop coil group 22Y to send out a magnetic field toward the electronic pen 23.

[0103] As shown in the first received signal 6B, in period D2, the control circuit 210 switches the transceiver switching circuit 204 to be connected to the receiving 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 received signal 6B. The first received 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 with the passage of 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 having a phase different from that of the clock signal CLK1 for operating 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 generation circuit 401 to transmit a transmission signal to the second electrode 42Y (transmission electrode) through the transmission electrode selection circuit 402.

[0107] As shown in the first received signal 6F, in periods D1 to D4, the control circuit 410 controls the reception electrode selection circuit 404 to receive the reception 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-described embodiment, when the waveforms of the first transmission signal and the second transmission signal are orthogonal, an example in which the value obtained by subtracting the frequency of the second transmission signal from the frequency of the first transmission signal is a positive or negative integer has been described. However, the present invention is not limited to this. For example, when the waveforms of the first transmission signal and the second transmission signal are orthogonal, it is sufficient that the inner product of the waveforms of the first transmission signal and the second transmission signal is 0, and the value obtained by subtracting the frequency of the second transmission signal from the frequency of the first transmission signal may be 0. In this case, as the first transmission signal, a sine wave, such as sin(2πmx), can be given, and as the second transmission signal, a cosine wave, such as cos(2πnx) where m = n, can be given. Note that on the side of the first receiving unit that receives the electromagnetic induction signal, since the phase of the signal transmitted by the electromagnetic induction pen is unknown, when the first transmission signal and the second transmission signal have the same frequency and only differ in phase (e.g., a sine wave and a cosine wave), it may be difficult to distinguish them. Therefore, when the first process is an electromagnetic induction method, it is preferable that, within the same period, the value obtained by subtracting the frequency of the second transmission signal from the frequency of the first transmission signal is a positive or negative integer.

[0115] Also, in the above-described embodiment, the electronic device 10 may adopt an in-cell method. The in-cell method is a method in which the display device 30 and the first electrode 42X or the second electrode 42Y in the second sensor 40 for detecting the position by the capacitance method are also used as the electrodes (e.g., the common electrode of a liquid crystal display, the negative electrode of an organic EL display) to which the potential necessary for driving the display pixels 32 of the display device 30 is supplied.

[0116] Also, in the above-described embodiments, all of them are merely examples of specific embodiments for implementing the present invention, and the technical scope of the present invention should not be construed in a limited manner by these. That is, the present invention can be implemented in various forms without departing from the gist or the main features thereof.

Explanation of Reference Numerals

[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 substrate, 42X: First electrode, 42X1: Signal line, 42Y: Second electrode, 42Y1: Signal line, 50: Control circuit board, 60: Planar member, 60a: Surface, 61: Region, 62: Frame region, 70: Housing, 71: Recess, 72: Frame region, 100: Indicator, 101: Position detection circuit, 200: Position detection circuit, 201: Selection circuit, 202: Oscillator, 203: Current driver, 204: Transmission / reception switching circuit, 205: Receiving amplifier, 206: Detection circuit, 207: Low-pass filter, 208: Sample 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: Receiving electrode selection circuit, 405: Received signal processing circuit, 406 Position information output circuit, 410: Control circuit, 411: Position indication status discrimination circuit

Claims

1. An indication position detection device for detecting an indication position by an indicator, comprising: a first transmission unit, a second transmission unit, and a display unit including display pixels; the first transmission unit transmits a first transmission signal related to a first process for detecting an indication position by an indicator; the second transmission unit transmits a second transmission signal related to a second process different from the first process to an electrode to which a potential for driving the display pixels is supplied; in the same period, the waveform of the first transmission signal and the waveform of the second transmission signal are orthogonal; an indication position detection device.

2. The indication position detection device according to claim 1, wherein: the first transmission signal is a sine wave; the second signal is a cosine wave; a value obtained by subtracting the frequency of the second transmission signal from the frequency of the first transmission signal is 0; an indication position detection device.

3. The indication position detection device according to claim 1, wherein: an inner product of the waveform of the first transmission signal and the waveform of the second transmission signal is 0; an indication position detection device.

4. The indication position detection device according to claim 1, wherein: in the same period, a value obtained by subtracting the frequency of the second transmission signal from the frequency of the first transmission signal is a positive or negative integer; an indication position detection device.

5. The indication position detection device according to claim 1, wherein: the first process is a process for detecting an indication position by an indicator by an electromagnetic induction method; the second process is a process for detecting an indication position by an indicator by a capacitance method; an indication position detection device.

6. The indication position detection device according to claim 1, wherein: a transmission period of the first transmission signal overlaps at least a part of a transmission period of the second transmission signal; an indication position detection device.

7. The indication position detection device according to claim 4, wherein: a start point and an end point of a transmission period of the first transmission signal are the same as a start point and an end point of a transmission period of the second transmission signal; an indication position detection device.

8. The indication position detection device according to claim 1, further comprising: a display; the first process is a process for detecting an indication position on the display by an indicator by an electromagnetic induction method; the second process is a process for driving the display; an indication position detection device.

9. The indication position detection device according to claim 1, further comprising: a display; the first process is a process for detecting an indication position on the display by an indicator by a capacitance method; The second process is a process of driving the display. Indicator position detection device.

10. An indicator position detection device for detecting an indicator position by an indicator, comprising a first transmission unit, a second transmission unit, a first reception unit, a second reception unit, and a display unit including display pixels, the first transmission unit transmits a first transmission signal related to a first process of detecting an indicator position by an indicator, the second transmission unit transmits a second transmission signal related to a second process of detecting an indicator position by an indicator to an electrode to which a potential for driving a display pixel is supplied, the first reception unit receives a first reception signal related to the first process, the second reception unit receives a second reception signal related to the second process via the electrode, in the same period, the waveform of the first reception signal and the waveform of the second reception signal are orthogonal to each other, Indicator position detection device.

11. The indicator position detection device according to claim 10, wherein the first transmission signal is a sine wave, the second signal is a cosine wave, and a value obtained by subtracting the frequency of the second transmission signal from the frequency of the first transmission signal is 0, Indicator position detection device.

12. The indicator position detection device according to claim 10, wherein an inner product of the waveform of the first transmission signal and the waveform of the second transmission signal is 0, Indicator position detection device.

13. The indicator position detection device according to claim 10, wherein in the same period, a value obtained by subtracting the frequency of the second reception signal from the frequency of the first reception signal is a positive or negative integer, Indicator position detection device.

14. The indicator position detection device according to claim 10, wherein the first reception unit receives the first reception signal during a transmission period of the second transmission signal, Indicator position detection device.

15. The indicator position detection device according to claim 10, wherein the second reception unit receives the second reception signal during a transmission period of the first transmission signal, Indicator position detection device.

16. The indicator position detection device according to claim 10, wherein a guard interval is provided between a reception period of the first reception signal and a reception period of the second reception signal, Indicator position detection device.

17. An indicator position detection device for detecting an indicator position by an indicator, comprising a first transmission unit, a second transmission unit, and an in-cell type display device, wherein the first transmission unit transmits a first transmission signal related to a first process of detecting an indicator position by an indicator, The second transmission unit transmits a second transmission signal related to a second process different from the first process to an electrode that drives a pixel of the display device, In 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 an indication position by an indicator by an electromagnetic induction method, The second process is a process of detecting an indication position by an indicator by a capacitance method. Indication position detection device.

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