Detection device

Abstract

To provide a detecting device that can expand the range in which an object to be detected on a detection region can be detected with high accuracy.SOLUTION: A detecting device includes a sensor region having a detection region, a plurality of electrodes provided in the detection region, and a detection circuit configured to detect an object to be detected on the detection region frame by frame based on a detected value of each of the electrodes. The detected values for each electrode are subjected to integration by electrode at predetermined intervals, to detect a position of the object to be detected in a space on the detection region, based on the number of times of integration made until an integrated value of one of the electrodes reaches or exceeds a predetermined value.SELECTED DRAWING: Figure 11

Description

Technical Field

[0001] The present invention relates to a detection device.

Background Art

[0002] In recent years, a detection system in which a detection device capable of detecting an external proximity object, so-called a touch panel, is mounted or integrated on a display device such as a liquid crystal display device is known (see, for example, Patent Documents 1 to 3). In such a detection system, in addition to a touch detection function for detecting contact of a detection object such as an operator's finger with a detection surface, a hover detection function for detecting the proximity state or gesture of a finger in the space on the detection area in a state where the finger is not touching the detection surface has attracted attention.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a configuration in which a plurality of electrodes are provided in a detection area, the capacitance generated in each electrode is detected, and the spatial coordinates of the position where the detection object exists on the detection area are detected. Compared with a configuration for detecting the planar coordinates of the touch detection position, it is necessary to increase the sensitivity by increasing the size of each electrode and to expand the detectable range in the detection circuit.

[0005] An object of the present invention is to provide a detection device capable of expanding the range in which a detection object on a detection area can be detected with high accuracy. [Means for solving the problem]

[0006] A detection device according to one aspect of the present invention comprises a sensor area provided with a detection region, a plurality of electrodes provided in the detection region, and a detection circuit that detects an object to be detected on the detection region in frame units based on the detection value of each of the plurality of electrodes, wherein the length of one frame period for detecting the object to be detected on the detection region differs depending on the relative distance between the sensor area and the object to be detected. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a plan view showing the schematic configuration of the detection device according to the embodiment. [Figure 2] Figure 2 is a schematic diagram showing the general cross-sectional configuration of a detection system to which the detection device according to this embodiment is applied. [Figure 3] Figure 3 is a block diagram showing an example of the configuration of the detection circuit of the detection device according to the embodiment. [Figure 4A] Figure 4A is a schematic diagram showing the positional relationship between the detected object's position in the detection area and each electrode. [Figure 4B] Figure 4B is a schematic diagram showing the spatial coordinates of the detected object in the space within the detection area. [Figure 5] Figure 5 shows an example of a specific circuit configuration of an AFE circuit related to a comparative example. [Figure 6] Figure 6 is a timing chart showing an example of operation in the comparative example shown in Figure 5. [Figure 7] Figure 7 is a diagram showing the relationship between the distance between the object being detected and the electrode, and the signal value. [Figure 8] Figure 8 shows an example of a specific circuit configuration of the AFE circuit according to the embodiment. [Figure 9] Figure 9 is a conceptual diagram showing an example of the detection period of the detection device according to the embodiment. [Figure 10] Figure 10 is a timing chart showing an example of the operation of the detection device according to the embodiment during the first period. [Figure 11]Figure 11 is a timing chart showing an example of operation during the second period of the detection device according to the embodiment. [Figure 12] Figure 12 is a conceptual diagram showing an example of a second period of the detection device according to the embodiment. [Figure 13] Figure 13 is a flowchart showing an example of processing in the detection device according to the embodiment. [Figure 14] Figure 14 shows an example of the input / output characteristics of an A / D conversion circuit. [Modes for carrying out the invention]

[0008] Embodiments for carrying out the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the embodiments described below. Furthermore, the components described below include those that are easily conceivable to those skilled in the art, and those that are substantially the same. Moreover, the components described below can be combined as appropriate. Furthermore, the disclosure is merely an example, and any modifications that can be easily conceived by those skilled in the art while maintaining the spirit of the invention are naturally included within the scope of the present invention. In addition, the drawings may schematically represent the width, thickness, shape, etc., of each part compared to the actual embodiment in order to clarify the explanation, but these are merely examples and do not limit the interpretation of the present invention. Furthermore, in this specification and in each drawing, elements similar to those described above in previously shown drawings are denoted by the same reference numerals, and detailed explanations may be omitted as appropriate.

[0009] Figure 1 is a plan view showing the schematic configuration of a detection device according to an embodiment. As shown in Figure 1, the detection device 1 comprises a sensor area 10 and a control circuit 20.

[0010] The sensor region 10 includes a sensor substrate 11, a plurality of electrodes 12 provided in the detection region AA of the sensor substrate 11, and wiring 13 extending from each of the plurality of electrodes 12. The control circuit 20 includes a control board 21, an AFE (Analog Front End) circuit 22, a processing circuit 23, a power supply circuit 24, and an interface circuit 25.

[0011] The detection area AA of the sensor substrate 11 is an area where a plurality of electrodes 12 arranged in a matrix in the Dx direction (first direction) and the Dy direction (second direction) are provided. The sensor substrate 11 is, for example, a glass substrate or a flexible printed circuit board (FPC: Flexible Printed Circuits) having translucency.

[0012] In the present disclosure, the Dx direction (first direction) and the Dy direction (second direction) are orthogonal in the detection area AA of the sensor substrate 11. Also, in the present disclosure, the direction orthogonal to the Dx direction (first direction) and the Dy direction (second direction) is defined as the Dz direction (third direction).

[0013] In the example shown in FIG. 1, an example in which five electrodes 12 are arranged in the Dx direction and four electrodes 12 are arranged in the Dy direction, and 5×4 (=20) electrodes 12 are provided is shown, but the number of electrodes 12 provided in the detection area AA of the sensor substrate 11 is not limited to this.

[0014] A control substrate 21 is electrically connected to the sensor substrate 11 via a wiring substrate 31. The wiring substrate 31 is, for example, a flexible printed circuit board. Each electrode 12 in the sensor area 10 is connected to the AFE circuit 22 of the control circuit 20 via the wiring substrate 31.

[0015] The control substrate 21 is provided with an AFE circuit 22, a processing circuit 23, a power supply circuit 24, and an interface circuit 25. The control substrate 21 is, for example, a rigid substrate.

[0016] The AFE circuit 22 generates a detection value of each electrode 12 based on the detection signal of each electrode 12 output from the sensor substrate 11. The AFE circuit 22 is, for example, an analog front-end IC.

[0017] The processing circuit 23 generates spatial coordinates indicating the position of the object to be detected (e.g., the operator's fingers) on the detection area AA, based on the detection values ​​of each electrode 12 output from the AFE circuit 22. The processing circuit 23 may be a PLD (Programmable Logic Device) such as an FPGA (Field Programmable Gate Array), or it may be an MCU (Micro Control Unit).

[0018] The power supply circuit 24 is a circuit that supplies power to the AFE circuit 22 and the processing circuit 23.

[0019] The interface circuit 25 is, for example, a USB controller IC, and is a circuit that controls communication between the processing circuit 23 and the host controller (not shown) of the host device on which the detection system is mounted.

[0020] Figure 2 is a schematic diagram showing the general cross-sectional configuration of a detection system to which the detection device according to this embodiment is applied.

[0021] The detection system 100 includes a detection device 1 and a display panel 200. The display panel 200 is positioned opposite the sensor area 10 of the detection device 1 via an air gap AG. The sensor area 10 of the detection device 1 is positioned such that, in a plan view, the detection area AA of the sensor area 10 and the display area DA of the display panel 200 overlap in the Dz direction (third direction). The display panel 200 is exemplified by, for example, a liquid crystal display (LCD). The display panel 200 may also be, for example, an organic light-emitting diode (OLED) display or an inorganic light-emitting diode (micro-LED, mini-LED).

[0022] The sensor area 10 comprises a sensor substrate 11, electrodes 12, a shield 14, and a cover glass 15. The sensor area 10 is stacked in the following order from the display panel 200 side: shield 14, sensor substrate 11, electrodes 12, and cover glass 15. Hereinafter, the surface of the cover glass 15, which is the uppermost layer, will also be referred to as the "detection surface".

[0023] The shield 14 is provided on the first surface of the sensor substrate 11 on the display panel 200 side. The electrode 12 is provided on the second surface of the sensor substrate 11 on the back side of the first surface. The cover glass 15 is provided on the second surface of the sensor substrate 11 via an adhesive layer OC. It is desirable that the adhesive layer OC be made of a light-transmitting adhesive. The adhesive layer OC may be formed of a light-transmitting film with double-sided adhesive properties, such as OCA (Optical Clear Adhesive).

[0024] Figure 3 is a block diagram showing an example of the configuration of the detection circuit of the detection device according to the embodiment.

[0025] As shown in Figure 3, the detection circuit 40 includes a detection timing control circuit 41, a signal detection circuit 42, an A / D conversion circuit 43, a signal processing circuit 44, and a coordinate extraction circuit 45. In this disclosure, the detection timing control circuit 41, the signal detection circuit 42, and the A / D conversion circuit 43 are included in the AFE circuit 22. The signal processing circuit 44 and the coordinate extraction circuit 45 are included in the processing circuit 23.

[0026] The detection timing control circuit 41 is a component that controls the detection operation timing in the signal detection circuit 42 and the A / D conversion circuit 43. The specific operation of the detection timing control circuit 41 in this disclosure will be described later.

[0027] The signal detection circuit 42 generates an output value GV(n) for each electrode 12 based on the detection signal Det(n) (where n is a natural number from 1 to N, and N is the number of electrodes in the detection region AA) output from the sensor board 11. The A / D conversion circuit 43 samples the output value GV(n) from the signal detection circuit 42 and converts it into a discrete detection value Raw(n).

[0028] The signal processing circuit 44 performs predetermined signal processing on the detected value Raw(n) for each electrode 12 and calculates the signal value S(n) for each electrode 12. Specific examples of the processing in the signal processing circuit 44 will be described later.

[0029] The coordinate extraction circuit 45 extracts the spatial coordinates of the location where the object to be detected is located, based on the signal value S(n) for each electrode 12 output from the signal processing circuit 44.

[0030] Figure 4A is a schematic diagram showing the position of the object to be detected in the space on the detection region and its positional relationship with each electrode. Figure 4B is a schematic diagram showing the spatial coordinates of the object to be detected in the space on the detection region. Figures 4A and 4B show an example in which the object to be detected F is located in the space on the detection region AA.

[0031] As shown in Figure 4A, each electrode 12 in the detection region AA generates a capacitance corresponding to the distance D(n) between the object to be detected F in the space on the detection region AA and each electrode 12, and a signal value S(n) corresponding to that capacitance is obtained.

[0032] The processing circuit 23 uses the generated signal values ​​S(n) from each electrode 12 to extract spatial coordinates R(Rx, Ry, Rz) that indicate the position of the detected object F in the space on the detection region AA shown in Figure 4B.

[0033] In this disclosure, the spatial coordinate R(Rx, Ry, Rz) includes a first data Rx indicating the position in the Dx direction (first direction) on the detection region AA, a second data Ry indicating the position in the Dy direction (second direction) on the detection region AA, and a third data Rz indicating the position in the Dz direction (third direction) which is orthogonal to the Dx direction (first direction) and the Dy direction (second direction).

[0034] Furthermore, in this disclosure, the spatial coordinates R(Rx, Ry, Rz) indicate the position of the object to be detected F in the space on the detection surface of the cover glass 15, with the surface of the detection surface being used as the detection surface.

[0035] As described above, the detection device 1 according to this disclosure is configured to detect the spatial coordinates of the location of the object to be detected F on the detection region AA by detecting the capacitance generated in each electrode 12. Therefore, in order to detect the object to be detected F located at a position away from the detection region AA in the Dz direction, it is necessary to increase the size of each electrode 12 to improve sensitivity compared to a configuration that detects the planar coordinates of the contact position of the object to be detected F with the detection surface. In this disclosure, the size of each electrode 12 is, for example, 20 × 20 [mm]. 2 ]~50×50[mm 2 This is an estimate. In other words, the distance between each electrode 12 in the Dx and Dy directions is expected to be, for example, about 20 mm to 50 mm.

[0036] Figure 5 shows an example of a specific circuit configuration of an AFE circuit related to a comparative example. Figure 5 illustrates a comparative example corresponding to the configuration of the embodiment described later.

[0037] In the comparative example shown in Figure 5, the signal detection circuit 142 of the AFE circuit 122 includes a differential amplifier circuit CA(n) and an amplifier circuit PGA(n) as its main components.

[0038] The non-inverting input terminals of the differential amplifier circuit CA(n) are connected to a first switch circuit SW1 and a second switch circuit SW2, to which a first reference potential VDD and a second reference potential GND are selectively applied. The first switch circuit SW1 is controlled on / off by a first switch control signal SW1ctrl output from the detection timing control circuit 141. The second switch circuit SW2 is controlled on / off by a second switch control signal SW2ctrl output from the detection timing control circuit 141.

[0039] Specifically, when the first switch circuit SW1 is controlled to ON and the second switch circuit SW2 is controlled to OFF, the first reference potential VDD is applied to the non-inverting input terminal of the differential amplifier circuit CA(n). Conversely, when the first switch circuit SW1 is controlled to OFF and the second switch circuit SW2 is controlled to ON, the second reference potential GND is applied to the non-inverting input terminal of the differential amplifier circuit CA(n). By controlling the ON / OFF states of the first switch circuit SW1 and the second switch circuit SW2, a rectangular wave-shaped reference signal REF_SIG is input to the non-inverting input terminal of the differential amplifier circuit CA(n), with the high potential (hereinafter also referred to as the "H" potential) being the first reference potential VDD and the low potential (hereinafter also referred to as the "L" potential) being the second reference potential GND. Note that, although the second reference potential is set to GND here, it is not limited to this, and the second reference potential can be any value smaller than the first reference potential.

[0040] The other inverting input terminal of the differential amplifier circuit CA(n) is connected to electrode 12_n, which is provided in the detection region AA. Furthermore, a negative feedback capacitor Cfb and a reset switch circuit RSW for resetting the negative feedback capacitor Cfb are provided between the inverting input terminal and the output terminal of the differential amplifier circuit CA(n). The differential amplifier circuit CA(n) functions as an integrating circuit with the above configuration. The reset switch circuit RSW is controlled on / off by the reset switch control signal RSWctrl output from the detection timing control circuit 141.

[0041] The amplifier circuit PGA(n) amplifies the output value V(n) of the differential amplifier circuit CA(n). When the gain of the amplifier circuit PGA(n) is G, the output value of the signal detection circuit 142 can be expressed as GV(n), which is the output value V(n) of the differential amplifier circuit CA(n) multiplied by the gain G.

[0042] Next, the operation in the comparative example shown in Figure 5 will be explained with reference to Figure 6. Figure 6 is a timing chart showing an example of operation in the comparative example shown in Figure 5. In Figure 6, when detecting the object to be detected F in the comparative example shown in Figure 5, an example is shown in which the detection of the object to be detected F is performed with M sampling period (M is a natural number greater than or equal to 1) as 1 frame (1[F]=M[T]).

[0043] In the comparative example shown in Figure 5, the negative feedback capacitance Cfb of the differential amplifier circuit CA(n) is reset with a sampling period of 1[T]_m (where m is a natural number from 1 to M).

[0044] Specifically, during the high period (hereinafter also referred to as the "H" period) and low period (hereinafter also referred to as the "L" period) of the reference signal REF_SIG after the reset of the negative feedback capacitance Cfb of the differential amplifier circuit CA(n), a charge corresponding to the distance D between the object to be detected F and each electrode 12 is charged to electrode 12_n. At this time, a detection signal Det(n) corresponding to the charge charged to electrode 12_n is input to the "-" terminal of the differential amplifier circuit CA(n). As a result, the negative feedback capacitance Cfb of the differential amplifier circuit CA(n) is charged, and GV(n)_1, GV(n)_2, GV(n)_3, ..., GV(n)_M, obtained by multiplying the output value V(n) of the differential amplifier circuit CA(n) by the gain G of the amplifier circuit PGA(n), are output from the signal detection circuit 142.

[0045] Figure 6 illustrates the output values ​​GV(n1)_1~GV(n1)_M of the signal detection circuit 142 at electrode 12_n1, GV(n2)_1~GV(n2)_M of the signal detection circuit 142 at electrode 12_n2, ​​and GV(n3)_1~GV(n3)_M of the signal detection circuit 142 at electrode 12_n3. Furthermore, in Figure 6, when D(n1) is the distance of electrode 12_n1 from the object F, D(n2) is the distance of electrode 12_n2 from the object F, and D(n3) is the distance of electrode 12_n3 from the object F, then D(n2) <D(n1)<D(n3)としている。

[0046] The A / D conversion circuit 43 samples the output values ​​GV(n)_1, GV(n)_2, GV(n)_3, ..., GV(n)_M from the signal detection circuit 142 with a sampling period of 1[T]_m, and outputs Raw(n)_1, Raw(n)_2, Raw(n)_3, ..., Raw(n)_M.

[0047] In the example shown in Figure 6, the detection device of the comparative example detects the presence or absence of the object to be detected F in the detection area AA for each frame, and outputs the spatial coordinates Rp(Rxp, Ryp, Rzp) (where p is a natural number) of the position of the object to be detected F in the detection area AA.

[0048] Specifically, in the example shown in Figure 6, the signal processing circuit 44 calculates the signal value S(n)_odd and the signal value S(n)_even by applying the following equations (1) and (2) respectively to the detected value Raw(n)_odd(Raw(n)_1,Raw(n)_3,···,Raw(n)_M-1) acquired during the "H" period of the reference signal REF_SIG, and the detected value Raw(n)_even(Raw(n)_2,Raw(n)_4,···,Raw(n)_M) acquired during the "L" period of the reference signal REF_SIG. In equation (2) below, S_max is the maximum gradation of the digital signal from the A / D conversion circuit 43 onward.

[0049] S(n)_odd = Raw(n)_odd …(1)

[0050] S(n)_even=S_max-Raw(n)_even…(2)

[0051] The signal processing circuit 44 then performs an averaging process for the signal values ​​S(n)_1, S(n)_2, ..., S(n)_M in one frame.

[0052] Figure 7 is a diagram showing the relationship between the distance between the object being detected and the electrode, and the signal value. In Figure 7, the horizontal axis represents the distance D between the object being detected F and the electrode 12, and the vertical axis represents the signal value S_odd (or signal value S_even).

[0053] The signal value S_odd (or signal value S_even) corresponds to the output value GV of the signal detection circuit 142, which is determined by the distance D between the object F to be detected and the electrode 12. The minimum gradation S_min of the signal value S_odd (or signal value S_even) corresponds to the data value "0" of the digital signal in the A / D conversion circuit 43 and beyond. The maximum gradation S_max of the digital signal in the A / D conversion circuit 43 and beyond corresponds to the data value "255" when the resolution in the processing of the A / D conversion circuit 43 and beyond is 8 bits. Note that Figure 7 shows an example where the gain of the amplification circuit PGA is G1, G2, and G3 (G1 <G2<G3)。

[0054] As shown in Figure 7, the rate of decrease of the signal value S_odd (or signal value S_even) decreases as the distance D between the detected object F and the electrode 12 increases. In other words, as the distance D between the detected object F and the electrode 12 increases, the rate of change of the signal value S_odd (or signal value S_even) decreases. In the region where the distance D between the detected object F and the electrode 12 is relatively large, the influence of the parasitic capacitance Cpara between the electrode 12 and the shield potential (e.g., GND potential) becomes larger than the capacitance Cdet generated in the electrode 12 according to the distance D between the detected object F and the electrode 12. Also, the influence of the quantization error of the signal value S_odd (or signal value S_even) becomes larger with respect to the change in distance D. For this reason, a margin (Bottom_margin) is set for the minimum gradation S_min of the signal value S_odd (or signal value S_even), and the lower limit of gradation that the signal value S_odd (or signal value S_even) can take is set as S_lower_lim.

[0055] Furthermore, as shown in Figure 7, the rate of increase of the signal value S_odd (or signal value S_even) increases exponentially as the distance D between the object to be detected F and the electrode 12 decreases. In other words, as the distance D between the object to be detected F and the electrode 12 decreases, the rate of change of the signal value S_odd (or signal value S_even) increases. In particular, in the detection device 1 according to this disclosure, the size of each electrode 12 is large (for example, 20 × 20 [mm]). 2 ]~50×50[mm 2Therefore, if the distance D between the detected object F and the electrode 12 is relatively small (for example, if the detected object F is in close proximity to or in contact with the detection surface), the signal value S_odd (or signal value S_even) may overflow. For this reason, a margin (Head_margin) is set for the maximum gradation S_max of the signal value S_odd (or signal value S_even), and the upper limit of the gradation that the signal value S_odd (or signal value S_even) can take is set as S_upper_lim.

[0056] In this way, by setting upper and lower limits for the signal value S_odd (or signal value S_even), the signal value S_odd (or signal value S_even) can be obtained in the linear region of the sampling process of the A / D conversion circuit 43 (the region in which the output value changes linearly with respect to changes in the input value of the A / D conversion circuit 43).

[0057] Here, if the distance D between the object to be detected F and the electrode 12 is relatively large, that is, if the gain G of the amplification circuit PGA is increased to improve the detection accuracy of the object to be detected F located far from the detection surface, the detection accuracy may decrease when the distance D between the object to be detected F and the electrode 12 is relatively small (for example, when the object to be detected F is located close to or in contact with the detection surface). Specifically, when the gain of the amplification circuit PGA is G3, the signal value S_odd (or signal value S_even) may overflow at the electrode 12 that is closer to the object to be detected F than the distance D_min_G3 shown in Figure 7. More specifically, in the example shown in Figure 6, if the distances D(n1) of electrode 12_n1 from the object F, D(n2) of electrode 12_n2 from the object F, and D(n3) of electrode 12_n3 from the object F are relatively small, then, for example, the signal value S_odd (or signal value S_even) corresponding to electrode 12_n2 may overflow, potentially reducing the detection accuracy of the spatial coordinates of the object F.

[0058] Furthermore, if the gain G of the amplification circuit PGA is reduced to improve the detection accuracy of the object to be detected F when the distance D between the object to be detected F and the electrode 12 is relatively small, that is, when the object to be detected F is located close to or in contact with the detection surface, the detection accuracy of the object to be detected F when the distance D between the object to be detected F and the electrode 12 is relatively large, that is, when the object to be detected F is located far from the detection surface, may decrease. Specifically, when the gain of the amplification circuit PGA is G1, the signal value S_odd (or signal value S_even) corresponding to the electrode 12 located at a distance greater than the distance D_max_G1 shown in Figure 7 from the object to be detected F becomes more susceptible to the effects of parasitic capacitance Cpara and quantization errors. More specifically, in the example shown in Figure 6, if the distances D(n1) of electrode 12_n1 from the object F, D(n2) of electrode 12_n2 from the object F, and D(n3) of electrode 12_n3 from the object F are relatively large, then, for example, the signal value S_odd (or signal value S_even) corresponding to electrodes 12_n1 and 12_n3 may be affected by parasitic capacitance Cpara and quantization errors, potentially reducing the detection accuracy of the object F.

[0059] The following describes a configuration and operation according to an embodiment that can expand the range in which the object to be detected F on the detection area AA can be detected with high accuracy. Figure 8 is a diagram showing a specific example of the circuit configuration of the AFE circuit according to the embodiment. Here, the differences from the comparative example described above will be explained in detail, and explanations similar to those in the comparative example may be omitted.

[0060] In the signal detection circuit 42 according to this embodiment, the electrode 12_n provided in the detection region AA is connected to the inverting input terminal of the differential amplifier circuit CA(n) via the third switch circuit SW3. The electrode 12_n is also connected to the second reference potential GND via the fourth switch circuit SW4. The third switch circuit SW3 is controlled on / off by the third switch control signal SW3ctrl output from the detection timing control circuit 41. The fourth switch circuit SW4 is controlled on / off by the fourth switch control signal SW4ctrl output from the detection timing control circuit 41.

[0061] Specifically, when the third switch circuit SW3 is turned ON and the fourth switch circuit SW4 is turned OFF, electrode 12_n is connected to the inverting input terminal of the differential amplifier circuit CA(n). Conversely, when the third switch circuit SW3 is turned OFF and the fourth switch circuit SW4 is turned ON, the inverting input terminal of the differential amplifier circuit CA(n) and electrode 12_n are disconnected, and the charge stored in electrode 12_n is reset. The charge on electrode 12_n is charged and discharged by the ON / OFF control of the third switch circuit SW3 and the fourth switch circuit SW4.

[0062] The amplifier circuit PGA(n) amplifies the output value V(n) of the differential amplifier circuit CA(n). When the gain of the amplifier circuit PGA(n) is G, the output value of the signal detection circuit 42 can be expressed as GV(n), which is the output value V(n) of the differential amplifier circuit CA(n) multiplied by the gain G.

[0063] The output value GV(n) of the signal detection circuit 42 according to this embodiment is output to the A / D conversion circuit 43 via the fifth switch circuit SW5. The fifth switch circuit SW5 is controlled on and off by the fifth switch control signal SW5ctrl output from the detection timing control circuit 41. The fifth switch control signal SW5ctrl is controlled to be on in synchronization with the sampling timing of the A / D conversion circuit 43.

[0064] Furthermore, in this embodiment, the output value GV(n) of the amplification circuit PGA(n) is output to the detection timing control circuit 41.

[0065] The detection timing control circuit 41 calculates the integrated value Vint(n) by applying the following equations (3) and (4) to the output values ​​GV(n)_odd and GV(n)_even of the signal detection circuit 42, respectively.

[0066] Vint(n)=GV(n)_odd…(3)

[0067] Vint(n) = GVDD - GV(n)_even …(4)

[0068] In this embodiment, the detection timing control circuit 41 has an integration threshold Vintth set for the integrated value Vint(n). The detection timing control circuit 41 performs a comparison calculation between the integrated value Vint(n) and the integration threshold Vintth and controls the sampling timing of the A / D conversion circuit 43. Specifically, the A / D conversion circuit 43 performs a sampling process of the output value GV(n) of the signal detection circuit 42 when the integrated value Vint(n) becomes equal to or greater than the integration threshold Vintth (Vint(n)≧Vintth). It is preferable that the integration threshold Vintth is set to a value smaller than the value corresponding to the upper limit grayscale S_upper_lim of the signal value S_odd (or signal value S_even) shown in Figure 7.

[0069] Next, the operation of the configuration of the embodiment shown in Figure 8 will be described with reference to Figures 9 to 12. Figure 9 is a conceptual diagram showing an example of the detection period of the detection device according to the embodiment. Figure 10 is a timing chart showing an example of operation during the first period of the detection device according to the embodiment. Figure 11 is a timing chart showing an example of operation during the second period of the detection device according to the embodiment. Figure 12 is a conceptual diagram showing an example of the second period of the detection device according to the embodiment.

[0070] As shown in Figure 9, the detection device 1 according to this embodiment has a first period PW for detecting the presence or absence of an object to be detected F in the space on the detection surface, and a second period PD for detecting the position of the object to be detected F in the space on the detection surface. The detection device 1 according to this embodiment detects an object to be detected F present in the space on the detection surface during the first period PW and then moves to the second period PD. Furthermore, if the position of the object to be detected F in the space on the detection surface cannot be detected during the second period PD, the detection device 1 according to this embodiment moves back to the first period PW.

[0071] Figures 10 and 11 show an example in which, similar to the comparative example shown in Figure 5, the detection of the target object F is performed with a sampling period of M (where M is a natural number greater than or equal to 1) as one frame (1[F]=M[T]).

[0072] In the configuration according to the embodiment shown in Figure 8, as in the comparative example shown in Figure 5, the negative feedback capacitance Cfb of the differential amplifier circuit CA(n) is reset at a sampling period of 1[T]_m (where m is a natural number from 1 to M).

[0073] Specifically, in the operation of the first period PW shown in Figure 10, the detection device 1 according to this embodiment is controlled to turn on the third switch circuit SW3 and turn off the fourth switch circuit SW4.

[0074] Figure 10 illustrates the output values ​​GV(n1)_1 to GV(n1)_M of the signal detection circuit 42 at electrode 12_n1, GV(n2)_1 to GV(n2)_M of the signal detection circuit 42 at electrode 12_n2, ​​and GV(n3)_1 to GV(n3)_M of the signal detection circuit 42 at electrode 12_n3.

[0075] In the example of operation during the first period PW shown in Figure 10, the output values ​​GV(n1)_1~GV(n1)_M of the signal detection circuit 42 at electrode 12_n1, GV(n2)_1~GV(n2)_M of the signal detection circuit 42 at electrode 12_n2, ​​and GV(n3)_1~GV(n3)_M of the signal detection circuit 42 at electrode 12_n3 illustrate a state in which the parasitic capacitance Cpara has a large influence on the capacitance Cdet(n) generated at each electrode 12. In other words, during the first period PW, it indicates that the object to be detected F is not present in the space on the detection region AA, or that the object to be detected F is located at a relatively distant position in the space on the detection region AA. During this first period PW, the detection device 1 acquires the signal value S(n) for each electrode 12 at a predetermined frame rate, as shown in Figure 9.

[0076] In this first period PW operation example, the detection device 1 according to this embodiment charges each electrode 12 with a charge corresponding to the distance D between the object to be detected F and each electrode 12. At this time, a detection signal Det(n) corresponding to the charge charged on each electrode 12 is input to the "-" terminal of the differential amplifier circuit CA(n). As a result, the negative feedback capacitance Cfb of the differential amplifier circuit CA(n) is charged.

[0077] The signal processing circuit 44 calculates the sum of the signal values ​​S(n) for each electrode 12 calculated using equations (1), (2), and (3) above.

[0078] In this embodiment, the signal processing circuit 44 has a total threshold Ssumth set for the total value Ssum. In the first period PW, the signal processing circuit 44 performs a comparison calculation between the total value Ssum and the total threshold Ssumth. The detection device 1 moves to the second period PD if, in the comparison calculation in the signal processing circuit 44, Ssum ≥ Ssumth. It is preferable that the total threshold Ssumth is set to a value greater than the lower limit grayscale S_lower_lim of the signal value S_odd (or signal value S_even) shown in Figure 7.

[0079] In the second period PD operation example shown in Figure 11, the detection device 1 according to this embodiment controls the third switch circuit SW3 to ON and the fourth switch circuit SW4 to OFF during the "H" and "L" periods of the reference signal REF_SIG after the reset of the negative feedback capacitance Cfb of the differential amplifier circuit CA(n). As a result, a charge corresponding to the distance D between the object to be detected F and each electrode 12 is charged to each electrode 12. At this time, a detection signal Det(n) corresponding to the charge charged to each electrode 12 is input to the "-" terminal of the differential amplifier circuit CA(n). This charges the negative feedback capacitance Cfb of the differential amplifier circuit CA(n).

[0080] Then, the third switch circuit SW3 is turned off and the fourth switch circuit SW4 is turned on, so that the charge in the negative feedback capacitor Cfb is maintained, and the charge charged on each electrode 12 is reset. After that, the third switch circuit SW3 is turned on again and the fourth switch circuit SW4 is turned off, so that a charge corresponding to the distance D between the object to be detected F and each electrode 12 is charged on each electrode 12, and a detection signal Det(n) corresponding to the charge charged on each electrode 12 is input to the "-" terminal of the differential amplifier circuit CA(n). As a result, the negative feedback capacitor Cfb of the differential amplifier circuit CA(n) is charged.

[0081] In the second-period PD operation example shown in Figure 11, the charge charged to the negative feedback capacitance Cfb of the differential amplifier circuit CA(n) is accumulated by repeating the charge-discharge operation described above within one sampling period.

[0082] Figure 11 illustrates the output values ​​GV(n1)_1~GV(n1)_M of the signal detection circuit 42 at electrode 12_n1, GV(n2)_1~GV(n2)_M of the signal detection circuit 42 at electrode 12_n2, ​​and GV(n3)_1~GV(n3)_M of the signal detection circuit 42 at electrode 12_n3. Also, in Figure 11, similar to the comparative example shown in Figure 5, when the distance of electrode 12_n1 from the object F to be detected is D(n1), the distance of electrode 12_n2 from the object F to be detected is D(n2), and the distance of electrode 12_n3 from the object F to be detected is D(n3), then D(n2) <D(n1)<D(n3)としている。

[0083] In the second period PD operation example shown in Figure 11, the detection timing control circuit 41 performs a comparison calculation between all the integrated values ​​Vint(n) of the signal detection circuit 42 and the integrated threshold Vintth. When one of the integrated values ​​Vint(n) corresponding to each electrode 12 becomes Vint(n) ≥ Vintth, the on / off control of the third switch circuit SW3 and the fourth switch circuit SW4 is stopped, the sampling timing of the A / D conversion circuit 43 is controlled, and the fifth switch circuit SW5 is turned on in synchronization with the sampling timing. As a result, the output value GV(n) of the signal detection circuit 42 is output to the A / D conversion circuit 43. Figure 11 shows an example where Vint(n) ≥ Vintth for the output values ​​GV(n2)_1 to GV(n2)_M of the signal detection circuit 42 at electrode 12_n2.

[0084] Furthermore, in this embodiment, the detection timing control circuit 41 has the function of counting and resetting the number of on / off controls of the third switch circuit SW3 and the fourth switch circuit SW4 during the "H" and "L" periods of the reference signal REF_SIG, in other words, the number of charge / discharge cycles (count value) CV of the electrode 12. The detection timing control circuit 41 starts counting the number of charge / discharge cycles (count value) CV of the electrode 12 in synchronization with the on / off control of the first switch circuit SW1 and the second switch circuit SW2, and resets the number of charge / discharge cycles (count value) CV of the electrode 12 when the negative feedback capacitance Cfb is reset. That is, the detection timing control circuit 41 resets the number of charge / discharge cycles (count value) CV of the electrode 12 and starts counting at each sampling period.

[0085] Furthermore, in this embodiment, the detection timing control circuit 41 has a count threshold Cvth set for the number of charge / discharge cycles (count value) Cv of the electrode 12. Specifically, it is preferable that the count threshold Cvth is set to a value that allows it to be considered that the object to be detected F does not exist in the space on the detection region AA.

[0086] In the example of operation of the second period PD shown in Figure 11, the detection timing control circuit 41 performs a comparison calculation process between the number of charge / discharge cycles (count value) Cv of the electrode 12 and the count threshold Cvth. When the number of charge / discharge cycles (count value) Cv of the electrode 12 becomes equal to or greater than the count threshold Cvth (Cv≧Cvth), the circuit proceeds to the first period PW.

[0087] The length of one sampling period 1[T]_m in the second period PD of the detection device 1 according to this embodiment is determined according to the result of a comparison calculation between all the integrated values ​​Vint(n) of the signal detection circuit 42 and the integrated threshold Vintth. Specifically, sampling is performed when one of the integrated values ​​Vint(n) corresponding to each electrode 12 becomes Vint(n) ≥ Vintth. That is, in this second period PD, the sampling timing for acquiring the signal value S(n) for each electrode 12 is determined according to the result of a comparison calculation between the integrated value Vint(n) and the integrated threshold Vintth.

[0088] More specifically, the larger the relative distance D between the object to be detected F and the electrode 12, the larger the charge / discharge cycle (count value) Cv of the electrode 12, and the longer the sampling period 1[T]_m in the second period PD. Conversely, the smaller the relative distance D between the object to be detected F and the electrode 12, the smaller the charge / discharge cycle (count value) Cv of the electrode 12, and the shorter the sampling period 1[T]_m in the second period PD. As a result, as shown in Figure 12, the length of one frame period is longer when the position of the object to be detected F on the detection area AA is farther from the detection surface, and shorter when the position of the object to be detected F on the detection area AA is closer to the detection surface.

[0089] Thus, in the second period PD of the detection device 1 according to this embodiment, the detection device 1 acquires the signal value S(n) for each electrode 12 at a sampling timing determined according to the result of a comparison calculation between the total integrated value Vint(n) of the signal detection circuit 42 and the integrated threshold Vintth. As a result, in the second period PD, unlike the first period PW in which the signal value S(n) for each electrode 12 is acquired at a predetermined frame rate, the length of one frame period differs depending on the relative distance D between the sensor area 10 and the object to be detected F, as shown in Figure 12.

[0090] Furthermore, in this embodiment, the integrated value Vint(n) satisfying Vint(n)≧Vintth is greater than or equal to the integrated threshold Vintth, regardless of the magnitude of the distance D(n) of the electrode 12 from the object F to be detected. In this embodiment, the subsequent coordinate extraction circuit 45 performs weighting processing on the signal value S(n) of each electrode 12 output from the signal processing circuit 44, according to the number of charge / discharge cycles (count value) Cv of the electrode 12, and performs spatial coordinate extraction processing of the position where the object F to be detected exists. As a result, position information in the Dz direction on the detection surface of the object F to be detected is completed.

[0091] In the example of operation of the second period PD shown in Figure 11, the number of charge / discharge cycles (count value) Cv of electrode 12 may be output every frame, or it may be output every sampling period of 1[T]_m. Furthermore, when the number of charge / discharge cycles (count value) Cv of electrode 12 is output every frame, it may be output after averaging the number of charge / discharge cycles (count value) Cv acquired every sampling period of 1[T]_m, or the coordinate extraction circuit 45 may average the number of charge / discharge cycles (count value) Cv output from the detection timing control circuit 41 every sampling period of 1[T]_m.

[0092] Here, in the second period PD of the detection device 1 according to this embodiment, even if there is no object to be detected F in the space on the detection region AA, charge may accumulate in the negative feedback capacitance Cfb of the differential amplifier circuit CA(n) due to the parasitic capacitance Cpara generated between each electrode 12 and the shield potential (for example, the GND potential), and the integrated value Vint(n) may become greater than or equal to the integration threshold Vintth (Vint(n)≧Vintth).

[0093] In the detection device 1 according to this embodiment, as described above, in the first period PW, a comparison calculation is performed between the sum of the signal values ​​S(n) for each electrode 12, Ssum, and the total threshold Ssumth. When the sum of the signal values ​​S(n) for each electrode 12, Ssum, becomes greater than or equal to the total threshold Ssumth (Ssum ≥ Ssumth), the device proceeds to the second period PD.

[0094] Furthermore, in the detection device 1 according to this embodiment, as described above, in the second period PD, a comparison calculation process is performed between the number of charge / discharge cycles (count value) Cv of the electrode 12 and the count threshold Cvth, and when the number of charge / discharge cycles (count value) Cv of the electrode 12 becomes Cv ≥ Cvth, the device proceeds to the first period PW.

[0095] As a result, in the second period PD, charges are accumulated in the negative feedback capacitance Cfb of the differential amplifier circuit CA(n) by the parasitic capacitance Cpara generated between each electrode 12 and the shield potential (for example, the GND potential), and it is possible to prevent the false detection of the detected object F when the detected object F does not actually exist in the space above the detection region AA.

[0096] Next, the processing in the detection device according to the embodiment will be described with reference to FIG. 13. FIG. 13 is a flowchart showing an example of the processing in the detection device according to the embodiment.

[0097] When the detection device 1 starts the detection operation in the first period PW (step S101), the signal processing circuit 44 acquires the signal value S(n) for each electrode 12 (step S102) and calculates the total value Ssum of the signal values S(n) for each electrode 12 (step S103).

[0098] Then, the signal processing circuit 44 performs a comparison operation process between the total value Ssum calculated in step S103 and the total threshold value Ssumth (step S104).

[0099] If the total value Ssum of the signal values S(n) for each electrode 12 is less than the total threshold value Ssumth (Ssum < Ssumth, step S104; No), the processes from step S102 to step S104 are repeatedly executed.

[0100] When the signal value S(n) for each electrode 12 becomes equal to or greater than the total threshold value Ssumth (Ssum ≧ Ssumth, step S104; Yes), the detection device 1 shifts from the first period PW to the second period PD (step S105).

[0101] When shifting to the second period PD (step S105), the detection timing control circuit 41 resets the charge and discharge count (count value) Cv of the electrode 12 (Cv = 0) (step S106).

[0102] The detection timing control circuit 41 acquires the output value GV(n) of the signal detection circuit 42 (step S108), and calculates the integrated value Vint(n) for each electrode 12 (step S109).

[0103] Then, the detection timing control circuit 41 performs a comparison operation process between the integrated value Vint(n) for each electrode 12 calculated in step S109 and the integration threshold value Vintth (step S110).

[0104] If the integrated value Vint(n) of all the electrodes 12 is less than the integration threshold value Vintth (Vint(n) < Vintth) (step S110; No), the detection timing control circuit 41 performs a comparison operation process between the charge / discharge count (count value) Cv of the electrode 12 and the count threshold value Cvth (step S111).

[0105] When the charge / discharge count (count value) Cv of the electrode 12 is less than the count threshold value Cvth (Cv < Cvth, step S111; No), the process returns to step S108, and until one of the integrated values Vint(n) for each electrode 12 becomes greater than or equal to the integration threshold value Vintth (Vint(n) ≥ Vintth) (step S110; Yes), or until the charge / discharge count (count value) Cv of the electrode 12 becomes greater than or equal to the count threshold value Cvth (Cv ≥ Cvth, step S111; Yes), the above-described process is repeatedly executed.

[0106] When one of the integrated values ​​Vint(n) for each electrode 12 becomes greater than or equal to the integration threshold Vintth (Vint(n)≧Vintth) (Step S110; Yes), the detection timing control circuit 41 of the AFE circuit 22 controls the sampling timing of the A / D conversion circuit 43, and the A / D conversion circuit 43 performs sampling processing of the output value GV(n) of the signal detection circuit 42 to obtain the detected value Raw(n). The AFE circuit 22 outputs the charge / discharge count (count value) Cv of the electrode 12 at that time and the detected value Raw(n) obtained by the A / D conversion circuit 43 to the subsequent processing circuit 23 (Step S112). Then, the process returns to step S106, and the above process is repeatedly executed until one of the cumulative values ​​Vint(n) for each electrode 12 becomes equal to or greater than the cumulative threshold Vintth (Vint(n)≧Vintth) (step S110; Yes), or until the number of charge / discharge cycles (count value) Cv of the electrode 12 becomes equal to or greater than the count threshold Cvth (Cv≧Cvth, step S111; Yes).

[0107] When the number of charge / discharge cycles (count value) Cv of electrode 12 becomes greater than or equal to the count threshold Cvth (Cv ≥ Cvth, step S111; Yes), the process returns to step S101. As a result, the detection device 1 transitions from the second period PW to the second period PD (step S101).

[0108] Figure 14 shows an example of the input / output characteristics of an A / D conversion circuit. In Figure 14, the horizontal axis represents the output value GV of the signal detection circuit 42 input to the A / D conversion circuit 43, and the vertical axis represents the detected value Raw corresponding to the output value GV of the signal detection circuit 42.

[0109] The number of grayscale levels of the detected Raw value that can be output from the A / D conversion circuit 43 is 2 n In this case, the minimum gradation Raw_min is "0", and the maximum gradation Raw_max is "2 nThis becomes "-1". Specifically, for example, if the resolution of the A / D conversion circuit 43 is 12 bits (n=12), the minimum gradation Raw_min will be "0" and the maximum gradation Raw_max will be "4095". Figure 14 shows an example where the resolution of the A / D conversion circuit 43 is 5 bits (n=5). In this case, the minimum gradation Raw_min will be "0" and the maximum gradation Raw_max will be "31".

[0110] Furthermore, in Figure 14, the lower grayscale limit considering the effect of quantization error is defined as Raw_lower_lim, and the upper grayscale limit considering the overflow margin is defined as Raw_upper_lim.

[0111] In the configuration and operation of the comparative example described above (Figures 5 and 6), the range indicated by the solid arrow in Figure 14 represents the acquisition range of the output value GV and the detected value Raw when the object to be detected F is relatively close to the sensor area 10, and the range indicated by the dashed arrow in Figure 14 represents the detection range of the output value GV and the detected value Raw when the object to be detected F is relatively far from the sensor area 10.

[0112] In the configuration and operation of the comparative example described above (Figures 5 and 6), the range of the detection value Raw used for detecting the position of the object to be detected F is from the lower grayscale Raw_lower_lim to the output value GV and detection value Raw of the electrode 12 closest to the object to be detected F. In other words, the range of the detection value Raw (dashed line) when the object to be detected F is relatively far from the sensor area 10 is relatively narrower than the range of the detection value Raw (solid line) when the object to be detected F is relatively close to the sensor area 10.

[0113] In contrast, the configuration and operation described herein perform a comparison calculation between all the integrated values ​​Vint(n) of the signal detection circuit 42 and the integrated threshold Vintth. When one of the integrated values ​​Vint(n) corresponding to each electrode 12 becomes greater than or equal to the integrated threshold Vintth (Vint(n)≧Vintth), the output value GV of each electrode 12 is acquired and converted into a detected value Raw. As a result, as shown by the dashed line in Figure 14, the range of the output value GV and the detected value Raw of each electrode 12 can be expanded when the object to be detected F is located relatively far from the sensor area 10.

[0114] In this embodiment, the detection device 1, through the process described above, ensures that the integrated value Vint(n) of the electrode 12 closest to the object to be detected F among the multiple electrodes 12 in the detection region AA is equal to or greater than the integrated threshold Vintth. As a result, the integrated value Vint(n) of the electrode 12 that is relatively farther from the object to be detected F also becomes a large value, and the grayscale range of the signal value S(n) acquired for each electrode 12 becomes relatively larger, thereby expanding the range in which the object to be detected F on the detection region AA can be detected with high accuracy.

[0115] Furthermore, the detection device 1 according to this embodiment performs weighting on the signal value S(n) for each electrode 12 according to the number of charge / discharge cycles (count value) Cv of the electrode 12, and performs spatial coordinate extraction processing for the location where the object to be detected F exists. As a result, positional information in the Dz direction on the detection surface of the object to be detected F is completed.

[0116] Furthermore, the detection device 1 according to this embodiment sets a first period PW for determining whether or not an object to be detected F exists in the space on the detection area AA, and a second period PD for detecting the position of the object to be detected F. In the second period PD, if the cumulative value Vint(n) of any electrode 12 in the detection area AA does not exceed the cumulative threshold Vintth, and the number of charge / discharge cycles (count value) Cv of the electrode 12 exceeds the count threshold Cvth, the device transitions from the second period PD to the first period PW. This prevents false detection of the object to be detected F when the object to be detected F does not exist in the space on the detection area AA.

[0117] While preferred embodiments of this disclosure have been described above, this disclosure is not limited to such embodiments. The content disclosed in the embodiments is merely an example, and various modifications are possible without departing from the spirit of this disclosure. Any modifications made without departing from the spirit of this disclosure will naturally fall within the technical scope of this disclosure. [Explanation of Symbols]

[0118] 1. Detection device 10 Sensor area 11 Sensor board 12 electrodes 13 Wiring 14 Shields 15 Cover glass 20 Control circuits 21 Control board 22 AFE Circuit 23 Processing Circuit 24 Power circuit 25 Interface Circuit 31 Wiring board 40 Detection Circuit 42 Signal detection circuit 43 A / D conversion circuit 44 Signal Processing Circuits 45 Coordinate extraction circuit 200 Display Panels AA detection area AG Air Gap DA display area F Detected object OC adhesive layer Rx Data 1 Ry 2nd Data Rz 3rd data

Claims

1. A sensor area in which a detection area is provided, Multiple electrodes provided in the detection region, A detection circuit that detects an object to be detected in the detection area on a frame-by-frame basis based on the detection values ​​for each of the multiple electrodes, Equipped with, Depending on the relative distance between the sensor area and the object to be detected, the length of one frame period for detecting the object on the detection area differs. The detection circuit is The detected values ​​for each electrode are accumulated at predetermined intervals for each electrode, and the position of the object to be detected in the space on the detection area is detected based on the number of accumulations until the accumulated value of one of the multiple electrodes exceeds a predetermined value. Detection device.

2. The detection circuit comprises a plurality of differential amplifier circuits, each of which is electrically connected to a plurality of electrodes. The charge corresponding to the number of charge-discharge cycles of the electrode is integrated into the negative feedback capacitance of the differential amplifier circuit. The detection device according to claim 1.

3. A sensor area in which a detection area is provided, Multiple electrodes provided in the detection region, A detection circuit that detects an object to be detected in the detection area on a frame-by-frame basis based on the detection values ​​for each of the multiple electrodes, Equipped with, Depending on the relative distance between the sensor area and the object to be detected, the length of one frame period for detecting the object on the detection area differs. The detection circuit is A first period in which the presence or absence of an object to be detected in the detection area is detected based on the sum of the detected values ​​for each of the multiple electrodes, A second period in which the detected value for each electrode is accumulated at predetermined intervals for each electrode, and the position of the object to be detected in the space on the detection area is detected based on the number of accumulations until the accumulated value of one of the plurality of electrodes exceeds a predetermined value, Having, Detection device.

4. The detection circuit comprises a plurality of differential amplifier circuits, each of which is electrically connected to a plurality of electrodes. During the second period, the charge corresponding to the number of charge-discharge cycles of the electrode is integrated into the negative feedback capacitance of the differential amplifier circuit. The detection device according to claim 3.

5. The detection circuit is During the first period, if the sum of the detected values ​​for each of the multiple electrodes exceeds a predetermined value, the process moves to the second period. During the second period, if the number of charge-discharge cycles exceeds a predetermined value, the system proceeds to the first period. The detection device according to claim 4.

6. Multiple electrodes are arranged in the detection region in a first direction and a second direction different from the first direction. The length of the side extending in the first direction is 20 mm or more and 50 mm or less. The length of the side extending in the second direction is 20 mm or more and 50 mm or less. A detection device according to any one of claims 1 to 5.

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