Detection device

Abstract

Provided is a detection device capable of suppressing the influence caused by propagation delay of an isolator. A detection device (1) is provided with: a sensor circuit (40) having a detection region; an AFE circuit (15) that acquires a detection signal from the sensor circuit (40); a control circuit (60) that controls the AFE circuit (15); a reference potential generation circuit (20) that operates with a first reference potential (GND1), which is a fixed potential, as a ground potential, and that generates a second reference potential (GND2) synchronized with the rectangular wave signal (Tx) output from the AFE circuit (15); a first isolator (16) provided in a transmission path of the rectangular wave signal (Tx) between the AFE circuit (15) and the reference potential generation circuit (20); and a second isolator (50) provided in a signal transmission path between an external processing device (110) having the first reference potential (GND1) as a ground potential and the control circuit (60). The AFE circuit (15) and the control circuit (60) operate with a second reference potential (GND2) as a ground potential. Signal transmission paths between the AFE circuit (15) and the control circuit (60) are electrically connected to each other.

Description

Technical Field

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

[0002] A detection device for detecting the proximity of an object is known (e.g., Patent Document 1). Such a detection device having a so-called hover detection (proximity detection) function includes a plurality of detection electrodes and a shielding electrode disposed around a detection area where the plurality of detection electrodes are disposed, and an electrical signal is supplied to the shielding electrode.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: U.S. Patent No. 9,151,792 Summary of the Invention

[0006] Technical problem to be solved by the invention

[0007] To improve the accuracy of suspension detection, a structure is being considered in which the ground potential of the detection block containing the detection circuit is set to a potential that periodically fluctuates in synchronization with the detection signal, and this potential is provided as the ground potential to the shielding electrode. In such a structure, isolators are provided in the power supply path and signal transmission path to the detection block, electrically isolating the peripheral circuits operating at a fixed potential as the ground potential from the circuits within the detection block. Examples of isolators include optically isolated photocouplers and magnetically isolated digital isolators. However, depending on the path in which the isolator is provided, the propagation delay of the isolator may limit the communication speed, making it impossible to achieve sufficient performance.

[0008] An object of the present disclosure is to provide a detection device capable of suppressing the influence of the propagation delay of an isolator.

[0009] Technical solutions to technical problems

[0010] One aspect of the present disclosure involves a detection device comprising: a sensor circuit having a detection area; an AFE circuit for acquiring a detection signal from the sensor circuit; a control circuit for controlling the AFE circuit; a reference potential generating circuit for operating with a first reference potential as a ground potential and generating a second reference potential synchronized with a rectangular wave signal output from the AFE circuit, wherein the first reference potential is a fixed potential; a first isolator provided in a transmission path of the rectangular wave signal between the AFE circuit and the reference potential generating circuit; and a second isolator provided in a signal transmission path between an external processing device that uses the first reference potential as a ground potential and the control circuit, wherein the AFE circuit and the control circuit operate with the second reference potential as a ground potential, and the signal transmission path between the AFE circuit and the control circuit is electrically connected to each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a diagram showing the main structure of the detection device according to the embodiment.

[0012] Figure 2A This is a schematic diagram showing an example of a schematic cross-sectional structure in which a sensor circuit and a display panel of a detection device according to an embodiment are stacked.

[0013] Figure 2B Yes Figure 2A Schematic diagram of a modified example of the schematic cross-sectional structure shown.

[0014] Figure 3 This is a schematic diagram showing a first connection example between the sensor circuit and the display panel of the detection device according to the embodiment.

[0015] Figure 4 This is a schematic diagram showing a second connection example between the sensor circuit and the display panel of the detection device according to the embodiment.

[0016] Figure 5 This is a diagram showing an example of a block configuration of a detection device according to an embodiment.

[0017] Figure 6 This is a schematic diagram showing an example of signal waveform changes in a reference potential generating circuit.

[0018] Figure 7 This is a schematic diagram showing an example of the operation of a low-pass filter.

[0019] Figure 8 This is a graph schematically showing the frequency characteristics of the resistance value of a digital potentiometer.

[0020] Figure 9This is a schematic diagram showing the flow of electricity in an electric field generated when the potential of the peripheral electrode is higher than the potential of the sensor electrode.

[0021] Figure 10 This is a schematic diagram showing the flow of electricity in an electric field generated when the potential of the peripheral electrodes is lower than the potential of the sensor electrodes.

[0022] Figure 11 : is a schematic graph showing an example of the detection signal intensity obtained from each sensor electrode.

[0023] Figure 12 This is a diagram showing an example of a functional circuit block configuration of a detection device according to an embodiment.

[0024] Figure 13 This is a schematic diagram showing a connection example in a structure in which a touch panel is stacked in addition to a display panel.

[0025] Figure 14 This is a flowchart showing an example of the hovering detection operation in the detection device.

[0026] Figure 15 This is a timing chart showing an example of the operation flow of a detection device capable of frequency hopping.

[0027] Figure 16 This is a diagram showing an example of a block configuration of a detection device according to the first embodiment.

[0028] Figure 17 This is a diagram showing an example of a functional circuit block configuration of the detection device according to the first embodiment.

[0029] Figure 18 This is a diagram showing an example of a block configuration of a detection device according to a modification of the embodiment.

[0030] Figure 19 This is a diagram showing an example of a functional circuit block configuration of a detection device according to a modification of the embodiment.

[0031] Figure 20 This is a diagram showing an example of a block structure of a detection device according to the second embodiment.

[0032] Figure 21 This is a diagram showing an example of a functional circuit block configuration of a detection device according to the second embodiment. DETAILED DESCRIPTION

[0033] With reference to the accompanying drawings, the modes (embodiments) for implementing the present invention are described in detail. It should be noted that the present invention is not limited to the contents described in the following embodiments. In addition, the constituent elements described below include elements that can be easily thought of by those skilled in the art, and substantially the same elements. Furthermore, the constituent elements described below can be appropriately combined. In addition, what is disclosed is ultimately just an example, and appropriate changes that can be easily thought of by those skilled in the art to maintain the gist of the invention are of course also included in the scope of the present invention. In addition, in order to make the description clearer, the width, thickness, shape, etc. of each part in the drawings are sometimes schematically indicated compared to the actual form, but after all, it is only an example and does not limit the interpretation of the present invention. In addition, in this specification and each figure, the same figure numerals are marked for the elements that are the same as those described in the accompanying drawings that have appeared, and detailed descriptions are sometimes appropriately omitted.

[0034] In this specification and claims, when expressing a form in which another structure is arranged above a certain structure, when simply expressed as "on", unless otherwise specified, it includes both a case in which the other structure is arranged directly above the certain structure in a manner connected to the certain structure, and a case in which the other structure is arranged above the certain structure with another structure interposed therebetween.

[0035] Figure 1 1 is a diagram showing the main structure of the detection device 1 involved in the embodiment. Figure 1 As shown, the detection device 1 includes a sensor circuit 40 and a detection circuit 2 .

[0036] Sensor circuit 40 is provided with multiple sensor electrodes (first electrodes) 42 and peripheral electrodes (second electrodes) 41 on a substrate 43. Detection device 1 is a hover detection device that detects the position and movement of a detected object, such as a finger, without contact with the detection surface of sensor circuit 40 (hereinafter also referred to as "hover detection"). In the present disclosure, detection device 1 performs hover detection using a self-capacitive method.

[0037] Sensor circuit 40 includes a detection area SA and a peripheral area BE outside the detection area SA. The detection area SA is an area where sensor electrodes 42 are provided and is used to detect objects approaching the detection surface. The peripheral area BE is an area outside the detection area SA where sensor electrodes 42 are not provided and is an area where peripheral electrodes 41 are provided along the four sides of the detection area SA.

[0038] It should be noted that in the following description, the first direction Dx is a direction within a plane parallel to the substrate 43. The second direction Dy is a direction within a plane parallel to the substrate 43 and is perpendicular to the first direction Dx. It should be noted that the second direction Dy does not need to be perpendicular to the first direction Dx, but rather intersects with it. The third direction Dz is a direction perpendicular to the first and second directions Dx and is the normal direction to the principal surface of the substrate 43. Furthermore, "viewed from above" refers to the positional relationship when viewed from a direction perpendicular to the substrate 43.

[0039] The sensor electrodes 42 are arranged in a matrix in the detection area SA of the substrate 43. In other words, the sensor electrodes 42 are aligned in the first direction Dx and the second direction Dy. The sensor electrodes 42 are electrically connected to the AFE circuit 15 via wiring (not shown).

[0040] The peripheral electrode 41 is arranged to surround the plurality of sensor electrodes 42 provided in the detection area SA.

[0041] The detection circuit 2 is connected to the sensor circuit 40. The detection circuit 2 includes, for example, an AFE circuit 15 that performs hovering detection based on the output of the sensor circuit 40, and a control circuit 60 that controls the hovering detection operation in the AFE circuit 15. The AFE circuit 15 is, for example, an analog front end (AFE). The control circuit 60 includes, for example, an MCU (Micro Control Unit).

[0042] A processing device (external processing device) 110 is connected to the detection circuit 2. The processing device 110 functions as the host computer (HOST) of the detection device 1 according to the embodiment. An example of the processing device 110 is a POS (Point of Sale) cash register terminal, but the present invention is not limited to this. Any terminal capable of accepting hover operations in the detection device 1 may be used.

[0043] Figure 2A 1 is a schematic diagram showing an example of a schematic cross-sectional structure of a stacked structure of the sensor circuit 40 and the display panel 250 of the detection device 1 according to the embodiment. The display panel 250 is a display panel that displays an output image. Figure 3 1 is a schematic diagram showing a first example of connection between the sensor circuit 40 and the display panel 250 of the detection device 1 according to the embodiment. Figure 3 , a so-called on-cell type device is exemplified in which the sensor circuit 40 of the detection device 1 according to the embodiment is mounted on a display panel 250 .

[0044] The display panel 250 includes an array substrate SUB1, an opposing substrate SUB2, a first polarizer PL1, and a second polarizer PL2. The first polarizer PL1, the array substrate SUB1, the opposing substrate SUB2, and the second polarizer PL2 are stacked in this order.

[0045] The array substrate SUB1 is a driving circuit substrate for driving a plurality of pixels. The counter substrate SUB2 is disposed opposite to the array substrate SUB1. A liquid crystal layer serving as a display function layer is disposed between the array substrate SUB1 and the counter substrate SUB2.

[0046] The sensor circuit 40 is bonded to the display panel 250 via an adhesive layer 260. As the adhesive layer 260, for example, OCA (Optical Clear Adhesive) is exemplified.

[0047] Multiple sensor electrodes 42 and peripheral electrodes 41 are provided on the same substrate 43. The substrate 43 is a film- or plate-shaped component formed from an insulating material, such as a resin film or a glass substrate. It should be noted that the sensor electrodes 42 and peripheral electrodes 41 are not limited to being provided on the same layer of the substrate 43; they can also be provided on different layers of the substrate 43. The sensor electrodes 42 are formed from, for example, a light-transmitting conductive material such as ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide). The peripheral electrodes 41 can be formed from the same material as the sensor electrodes 42 or from a different metal material, such as a metal material.

[0048] A cover member 270 is provided on the sensor circuit 40 via an adhesive layer 280. An example of adhesive layer 280 is OCA. Furthermore, a shield electrode 44 is provided on the surface of the substrate 43 opposite to the surface on which the sensor electrodes 42 and peripheral electrodes 41 are provided. In other words, the shield electrode 44 is provided between the surface of the sensor circuit 40 opposite to the surface on which the cover member 270 is provided and the display panel 250. Furthermore, an adhesive layer 260 is in contact with the shield electrode 44 provided on the sensor circuit 40.

[0049] The shielding electrode 44 includes, for example, a light-transmitting oxide or metal such as conductive ITO or IZO. Examples of the metal include molybdenum, tungsten, tantalum, aluminum, copper, and other metals (zero-valent metals). The shielding electrode 44 may have a single-layer structure or a stacked structure. When the shielding electrode 44 has a stacked structure, the shielding electrode 44 may include a layer containing an oxide and a layer containing a metal. As long as both layers of the shielding electrode 44 are transmissive and conductive, they may be referred to as a transparent conductive layer.

[0050] A second reference potential, described later, is supplied to the shield electrode 44. Furthermore, the shield electrode 44 is supplied with the same signal as that supplied to the peripheral electrode 41. In this embodiment, since the shield electrode 44 is provided between the sensor circuit 40 and the display panel 250, noise superimposed on the sensor electrode 42 of the sensor circuit 40 from the display panel 250 can be shielded.

[0051] The cover member 270 is attached to the sensor circuit 40. For example, a glass substrate or a resin substrate is used for the cover member 270. The upper surface of the cover member 270 is a detection surface in the hovering detection.

[0052] It should be pointed out that it can also be replaced by Figure 2A The simplified cross-sectional structure shown in FIG. Figure 2B A brief cross-sectional structure is shown. Figure 2B Yes Figure 2A Schematic diagram of a modified example of the schematic cross-sectional structure shown.

[0053] The display panel 250 is, for example, a liquid crystal display (LCD) panel. In this case, a backlight is provided on the opposite side of the sensor circuit 40 across the display panel 250. The display panel 250 is not limited thereto and may be, for example, an organic EL display panel (OLED) or an inorganic EL display panel (micro LED, mini LED). Alternatively, the display panel 250 may be an electrophoretic display panel (EPD) that uses electrophoretic elements as display elements.

[0054] exist Figure 3 In the so-called on-cell type device structure shown, the detection device 1 includes an FPC (Flexible Printed Circuits: flexible printed circuit board) 70. The FPC 70 is connected to a PCB (Printed Circuit Board: printed circuit board) 46. Various circuits constituting the detection circuit 2 are mounted on the PCB 46. Figure 3 , circuits 46a and 46b are shown as examples of various circuits constituting the detection circuit 2. The circuits 46a and 46b function as the AFE circuit 15 and the control circuit 60, for example.

[0055] Display panel 250 includes an FPC 255. Various circuits related to the operation of display panel 250 are provided on FPC 255. PCB 46 is connected to processing device 110 via cable 47. Cable 47 transmits signals generated between detection device 1 and processing device 110. Cable 47 is exemplified by a USB (Universal Serial Bus) cable.

[0056] Figure 4 : is a schematic diagram showing a second connection example between the sensor circuit 40 and the display panel 250 of the detection device 1 according to the embodiment. Figure 4 , a so-called in-cell type or hybrid type device is illustrated in which the sensor circuit 40 of the detection device 1 according to the embodiment is built into and integrated with the display panel 250. The display panel 250 in which the sensor circuit 40 of the detection device 1 according to the embodiment is built into and integrated with the display panel 250 includes, for example, a device that uses both a substrate, electrodes, and other parts used as the display panel 250 and a substrate, electrodes, and other parts used as the sensor circuit 40 of the detection device 1 according to the embodiment.

[0057] exist Figure 4 In the so-called in-cell type or hybrid type device structure shown, the FPC 255 is connected to the PCB 46. In this case, the cable 47 also has the function of transmitting signals generated between the display panel 250 and the processing device 110.

[0058] (Implementation Method 1)

[0059] Before describing the specific structure of the detection device 1 according to the first embodiment, the structure and operation of the detection device according to the embodiment will be described. Figure 5 It is a diagram showing an example of the block configuration of the detection device 1 according to the embodiment.

[0060] like Figure 5 As shown, in addition to the aforementioned sensor circuit 40, AFE circuit 15, and control circuit 60, detection device 1 further includes a reference potential generating circuit 20, a first isolator 16, a second isolator 50, and a power supply circuit 11. In the present disclosure, the sensor circuit 40 and AFE circuit 15 are included in the detection block 10. The control circuit 60 and the reference potential generating circuit 20 operate using a first reference potential GND1, which is a fixed potential, as the ground potential. Each circuit within the detection block 10, including the sensor circuit 40 and AFE circuit 15, operates using a second reference potential GND2 generated by the reference potential generating circuit 20 as the ground potential.

[0061] The power supply circuit 11 includes an isolated DC-DC converter 12 and linear regulators (LDOs) 13 and 14. The linear regulators 13 and 14 are included in the detection block 10.

[0062] The insulating DC-DC converter 12 isolates the processing device 110 from the detection block 10 and supplies power supplied from, for example, a power line VBUS of a USB cable to the detection block 10 .

[0063] The isolated DC-DC converter 12 is provided in a power supply path from an external device (processing device 110) whose ground potential is the first reference potential. The power supply source for the isolated DC-DC converter 12 is not limited to the processing device 110. The isolated DC-DC converter 12 may also be supplied with power from, for example, an AC adapter or other external power source.

[0064] Insulated DC-DC converter 12 supplies power to the coil on processing device 110, thereby generating a magnetic field in the coil. Detection block 10's coil is located within the range of influence of the magnetic field generated by the coil on processing device 110.

[0065] An induced electromotive force corresponding to the magnetic field generated by the coil on the processing device 110 is generated in the coil on the detection block 10. The power generated by the coil on the detection block 10 is converted into a voltage having the second reference potential GND2 as the ground potential and output to the linear regulators 13 and 14.

[0066] The linear regulators 13 and 14 are interposed between the isolated DC-DC converter 12 and the AFE circuit 15 , and adjust the output voltage to the AFE circuit 15 to a more appropriate voltage.

[0067] The linear regulator 13 uses the second reference potential GND2 as a ground potential and outputs a voltage required as an analog power supply AVDD of the AFE circuit 15 .

[0068] The linear regulator 14 uses the second reference potential GND2 as a ground potential and outputs a voltage required as an input / output power supply IOVDD of the AFE circuit 15 .

[0069] The AFE circuit 15 generates a drive signal for hover detection using a self-capacitive method and outputs the signal to the plurality of sensor electrodes 42 .

[0070] In the present disclosure, the AFE circuit 15 generates a rectangular wave signal Tx and outputs it to the reference potential generation circuit 20 via the first isolator 16. The rectangular wave signal Tx is an amplified signal of the drive signal output to the multiple sensor electrodes 42. The frequency of the drive signal for self-capacitive levitation detection (hereinafter also referred to as the "drive frequency") is substantially the same as the fundamental frequency of the rectangular wave signal Tx. The rectangular wave signal Tx includes the fundamental frequency component of the drive signal output to the multiple sensor electrodes 42 and higher harmonic components.

[0071] The first isolator 16 performs insulation between the reference potential generating circuit 20 and the detection block 10 and transmits the rectangular wave signal Tx output from the AFE circuit 15 .

[0072] Specifically, the rectangular wave signal output from the terminal on the reference potential generating circuit 20 side of the first isolator 16 having the first reference potential GND1 (fixed potential) as the ground potential is synchronized with the rectangular wave signal Tx output from the AFE circuit 15 having the second reference potential GND2 as the ground potential. Figure 5 In FIG. 1 , the waveform of the rectangular wave signal Tx output from the AFE circuit 15 is schematically shown as a waveform SB1 , and the waveform of the rectangular wave signal output to the reference potential generating circuit 20 via the first isolator 16 is schematically shown as a waveform SB2 .

[0073] Signal transmission between the detection block 10 side and the reference potential generating circuit 20 side in the first isolator 16 is performed using, for example, optical insulation using a photocoupler. Signal transmission between the detection block 10 side and the reference potential generating circuit 20 side in the first isolator 16 is not limited to optical insulation. For example, magnetic insulation based on the same principle as the isolated DC-DC converter 12 or capacitive insulation based on the principle of a capacitor may also be used.

[0074] The AFE circuit 15 and the control circuit 60 transmit signals such as sensing data and various control commands via the second isolator 50. Specifically, for example, the AFE circuit 15 outputs sensing data indicating a result of hovering detection to the control circuit 60 via the second isolator 50.

[0075] In this disclosure, signals between the AFE circuit 15 and the control circuit 60 are transmitted via SPI (Serial Peripheral Interface), a clock-synchronized serial interface. Note that the serial interface for transmitting signals between the AFE circuit 15 and the control circuit 60 is not limited to SPI.

[0076] The second isolator 50 performs insulation between the control circuit 60 and the detection block 10 and transmits signals between the AFE circuit 15 and the control circuit 60 .

[0077] Specifically, the electric signal output from the terminal on the control circuit 60 side of the second isolator 50 having the first reference potential GND1 (fixed potential) as the ground potential is synchronized with the electric signal output from the detection block 10 having the second reference potential GND2 as the ground potential.

[0078] Furthermore, the electrical signal output from the terminal on the detection block 10 side of the second isolator 50 having the second reference potential GND2 as the ground potential is synchronized with the electrical signal output from the control circuit 60 having the first reference potential GND1 (fixed potential) as the ground potential.

[0079] The signal transmission between the control circuit 60 side and the detection block 10 side in the second isolator 50 can be the same as or different from the signal transmission between the detection block 10 side and the reference potential generating circuit 20 side in the first isolator 16 described above. In other words, as the second isolator 50, an optically insulating photocoupler or a magnetically insulating digital isolator can be exemplified. The second isolator 50 is capable of bidirectional transmission of transmission output from the control circuit 60 side to the detection block 10 side and transmission output from the detection block 10 side to the control circuit 60 side. In the structure using an optically insulating photocoupler as the second isolator 50, the photocoupler that transmits output from the control circuit 60 side to the detection block 10 side and the photocoupler that transmits output from the detection block 10 side to the control circuit 60 side are connected in parallel.

[0080] The control circuit 60 and the processing device 110 transmit signals such as various information related to the sensing data and control instructions.

[0081] Furthermore, based on reference information (DP control reference data) indicating the correspondence between the fundamental frequency of the rectangular wave signal Tx output from the AFE circuit 15 and the resistance value of the digital potentiometer 22, described later, the control circuit 60 outputs a resistance value setting instruction to the digital potentiometer 22, which sets the resistance value of the digital potentiometer 22 to a resistance value corresponding to the fundamental frequency of the rectangular wave signal Tx output from the AFE circuit 15. Consequently, the resistance value of the digital potentiometer 22 is controlled to a resistance value corresponding to the fundamental frequency of the rectangular wave signal Tx.

[0082] In addition, the control circuit 60 performs noise determination processing on the sensing data and position determination of the detected object based on the sensing data (coordinate calculation processing). The noise determination processing is a process performed to determine the amount of noise components contained in the sensing data. In addition, the coordinate calculation processing is a calculation processing performed to determine the position of the detected object close to the sensor circuit 40. Specifically, in the coordinate calculation processing, for example, the position of the detected object in the first direction Dx, the position in the second direction Dy, and the position in the third direction Dz (see Figure 1 The details of the noise determination process and the coordinate calculation process are the same as those of the known processes, and therefore detailed descriptions thereof are omitted.

[0083] In this disclosure, signals between the control circuit 60 and the processing device 110 are transmitted via USB, a serial interface. Specifically, signals between the control circuit 60 and the processing device 110 are transmitted via signal lines D+ and D- of a USB cable. It should be noted that the serial interface for transmitting signals between the control circuit 60 and the processing device 110 is not limited to USB.

[0084] In the above configuration, the linear regulators 13 and 14 , the AFE circuit 15 , and the sensor circuit 40 included in the detection block 10 are electrically isolated from other components connected via the isolation DC-DC converter 12 , the first isolator 16 , and the second isolator 50 .

[0085] Furthermore, a first reference potential GND1 is provided as a ground potential to the processing device 110 side of the isolated DC-DC converter 12, the reference potential generation circuit 20 side of the first isolator 16, and the control circuit 60 side of the second isolator 50. The first reference potential GND1 is a fixed potential maintained by, for example, a large electrode such as a solid-surface electrode. It should be noted that a configuration including a magnetically isolated isolator and a DC-DC converter may be employed in place of the isolated DC-DC converter 12.

[0086] Meanwhile, a second reference potential GND2 is supplied as a ground potential to the detection block 10 side of the isolated DC-DC converter 12, the detection block 10 side of the first isolator 16, and the detection block 10 side of the second isolator 50. The second reference potential GND2 is a periodically varying potential generated by the reference potential generation circuit 20.

[0087] The period of fluctuation of the periodically fluctuating potential (second reference potential GND2) is the same as the period of rectangular wave generation of the drive signal (rectangular wave period of rectangular wave signal Tx) generated by the AFE circuit 15. In other words, the periodically fluctuating potential (second reference potential GND2) is a potential that periodically fluctuates in synchronization with the drive signal (rectangular wave signal Tx) generated by the AFE circuit 15.

[0088] Next, the reference potential generating circuit 20 will be described.

[0089] The reference potential generating circuit 20 includes a digital potentiometer (DP) 22, a low pass filter (LPF) 23, and an amplifier (AMP) 24. The digital potentiometer 22, the low pass filter 23, and the amplifier 24 operate with a first reference potential GND1, which is a fixed potential, as a ground potential.

[0090] The digital potentiometer 22 generates an intermediate frequency signal based on the rectangular wave signal output from the AFE circuit 15 via the first isolator 16. The digital potentiometer 22 is a digital potentiometer circuit (DP circuit) that generates a resistance value corresponding to a command from the processing device 110 on the output transmission path of the rectangular wave signal output from the AFE circuit 15 via the first isolator 16. The rectangular wave signal output from the AFE circuit 15 via the first isolator 16 becomes an intermediate frequency signal described later due to the resistance generated by the digital potentiometer 22. Figure 5 In FIG. 1 , the waveform of the intermediate frequency signal output from the digital potentiometer 22 is schematically represented as waveform SB3 .

[0091] The low-pass filter 23 removes high-frequency components from the intermediate-frequency signal outputted from the digital potentiometer 22. Specifically, the low-pass filter 23 is, for example, a Sallen-Key type fourth-order active filter.

[0092] In order to remove the high-frequency components of the intermediate frequency signal through the low-pass filter 23, the waveform is set to a generally rectangular waveform with a gentle change in the waveform, thereby preventing the unnecessary noise components from being amplified in the subsequent amplifier circuit 24 and increasing the radiation noise. More preferably, the output signal of the low-pass filter 23 is set to a generally sinusoidal waveform. Figure 5 , the waveform of the substantially sinusoidal output signal output from the low-pass filter 23 is schematically shown as waveform SB4. Here, the substantially sinusoidal wave refers to a waveform in which the influence of the sine wave and noise is substantially at the same level as the sine wave.

[0093] The amplifier circuit 24 is an inverting amplifier circuit that performs inverting amplification and impedance conversion on the substantially sinusoidal output signal from the low-pass filter 23. The signal inverted and amplified by the amplifier circuit 24 is provided as the second reference potential (GND2), which serves as the ground potential for each circuit within the detection block 10. Furthermore, the second reference potential (GND2) is provided to the peripheral electrodes 411 and 412 and the shield electrode 44 of the sensor circuit 40. Depending on the polarity of the signal input to the amplifier circuit 24, polarity inversion may or may not be performed in the amplifier circuit 24.

[0094] Figure 6 Schematic diagram showing an example of signal waveform changes in reference potential generating circuit 20. The rectangular wave signal output from AFE circuit 15 becomes an intermediate frequency signal due to the resistance of digital potentiometer 22. This intermediate frequency signal passes through low-pass filter 23 and becomes a substantially sinusoidal output signal.

[0095] In the present disclosure, the AFE circuit 15 has a function of setting the fundamental frequency of the rectangular wave signal Tx within the range of 140 kHz to 200 kHz. Figure 6 The example A shown shows a case where the fundamental frequency of the rectangular wave signal Tx is 200 kHz. Figure 6 Example B shows a case where the fundamental frequency of the rectangular wave signal Tx is 140 kHz. It should be noted that the frequency setting range (140 kHz to 200 kHz) of the rectangular wave signal Tx in the AFE circuit 15 is an example and is not limited thereto.

[0096] Figure 7 This is a diagram showing an example of the operation of a low-pass filter. Generally speaking, when a low-pass filter is used to generate a substantially sinusoidal signal from a rectangular wave signal, it is optimized to a single frequency. Specifically, for example, when a 140kHz rectangular wave signal is input to a low-pass filter optimized for 200kHz, Figure 7 As shown, the output signal of the low-pass filter may have a distorted signal waveform due to a time-series change in the signal intensity near the peak value.

[0097] In contrast, in the present disclosure, the resistance value of the digital potentiometer 22 is controlled to a value corresponding to the fundamental frequency of the rectangular wave signal Tx output from the AFE circuit 15, as shown in FIG. Figure 6 As shown, a substantially sinusoidal output signal can be generated in which distortion of time-series changes in signal intensity near a peak value of the output signal is suppressed.

[0098] Figure 8 : is a graph schematically showing the frequency characteristics of the resistance value of the digital potentiometer 22 . Figure 8 The horizontal axis represents the fundamental frequency of the rectangular wave signal Tx, and the vertical axis represents the resistance value of the digital potentiometer 22. Figure 8 The example shown shows that the resistance value of digital potentiometer 22 is controlled to be higher as the fundamental frequency of rectangular wave signal Tx decreases, and the resistance value of digital potentiometer 22 is controlled to be lower as the fundamental frequency of rectangular wave signal Tx increases. By controlling the resistance value of digital potentiometer 22 in accordance with the fundamental frequency of rectangular wave signal Tx, the subsequent low-pass filter 23 can stably generate a substantially sinusoidal output signal.

[0099] exist Figure 5In the block structure shown, the sensor circuit 40 includes a plurality of sensor electrodes 421, ..., 42n (n is a natural number), peripheral electrodes 411, 412, a substrate 43, and a shield electrode 44. Peripheral electrodes 411, 412 and sensor electrodes 421, ..., 42n are arranged on the substrate 43. Shield electrode 44 is a film- or plate-shaped electrode that faces sensor electrodes 421, ..., 42n across the substrate 43. Peripheral electrodes 411, 412 and shield electrode 44 function as an active shield whose potential periodically fluctuates in response to changes in the second reference potential (GND2) supplied from the reference potential generating circuit 20.

[0100] like Figure 5 As shown, the AFE circuit 15 is connected to the sensor electrodes 421, ..., 42n. The self-electrostatic capacitance of the sensor electrodes 421, ..., 42n generates an electrical signal output from each sensor electrode 421, ..., 42n to the AFE circuit 15. Therefore, the AFE circuit 15 can obtain the electrical signal output generated by the self-electrostatic capacitance of each sensor electrode 421, ..., 42n as a detection signal Rx indicating the state of the sensor circuit 40. The area where the sensor electrodes 421, ..., 42n are provided functions as a detection area SA (see Figure 1 ) In addition, the sensor electrodes 421, ..., 42n in the detection area SA function as detection electrodes in hover detection. In addition, the peripheral electrodes 411, 412 arranged around the detection area SA function as shield electrodes in hover detection.

[0101] Figure 9 This is a schematic diagram showing the flow of electricity in an electric field generated when the potential of the peripheral electrode 41 is higher than the potential of the sensor electrode 42 . Figure 10 This is a schematic diagram showing the flow of electricity in the electric field generated when the potential of the peripheral electrode 41 is lower than the potential of the sensor electrode 42. The detection signal strength obtained from each of the sensor electrodes 421, 422, and 423 changes when the object approaching the proximity sensor circuit 40 is at position P1 and when the object approaching the proximity sensor circuit 40 is at position P2.

[0102] Figure 11 4 is a schematic graph showing an example of the intensity of detection signals obtained from each of the sensor electrodes 421 , 422 , and 423 . Figure 9 The first example shown is a graph showing the intensity of detection signals obtained from each of the sensor electrodes 421 , 422 , and 423 when the subject is located at the position P1 . Figure 9The second example shown is a graph showing the intensity of detection signals obtained from each of the sensor electrodes 421 , 422 , and 423 when the subject is located at position P2 .

[0103] The AFE circuit 15 detects the proximity of the object to the sensor circuit 40 based on the relationship between the strength of the detection signal obtained from each of the sensor electrodes 421, ..., 42n (for example, sensor electrodes 421, 422, 423) and the amplitude provided to the peripheral electrodes 411, 412 when the detection signal indicating the strength of the detection signal is obtained. In this way, the proximity of the object to the sensor circuit 40 can be detected during hovering detection.

[0104] In the present disclosure, as described above, a second reference potential (GND2) is provided as the ground potential of the AFE circuit 15. Therefore, based on the input of the second reference potential (GND2), the AFE circuit 15 can obtain information indicating the potential of the peripheral electrodes 411 and 412 at the time of acquiring detection signals from the sensor electrodes 421, ..., 42n. This also makes it possible to detect whether a subject has entered the electric field generated between the peripheral electrodes 411 and 412 and the sensor electrodes 421, ..., 42n.

[0105] Figure 12 This is a diagram showing an example of a functional circuit block configuration of a detection device according to an embodiment.

[0106] like Figure 12 As shown, the AFE circuit 15 includes a readout circuit 151, an ADC (Analog Digital Converter) circuit 152, and a DSP (Digital Signal Processor) circuit 153. Each circuit element of the AFE circuit 15 operates with the second reference potential GND2, a periodically varying potential generated by the reference potential generation circuit 20, as the ground potential.

[0107] The readout circuit 151 acquires a detection signal Rx from each of the sensor electrodes 421 , . . . , 42 n.

[0108] The ADC circuit 152 converts the detection signal Rx acquired by the readout circuit 151 from an analog signal to a digital signal.

[0109] The DSP circuit 153 performs digital filtering processing on the digital data converted into a digital signal by the ADC circuit 152 to generate a detection signal Rx.

[0110] The AFE circuit 15 outputs the sensing data generated by the DSP circuit 153 to the control circuit 60 via the second isolator 50 .

[0111] The control circuit 60 includes a readout circuit 61, a noise determination circuit 62, a coordinate calculation circuit 63, and a storage circuit 64. Each circuit element of the control circuit 60 operates with the first reference potential GND1, which is a fixed potential, as a ground potential.

[0112] The readout circuit 61 acquires the sensing data output from the AFE circuit 15 via the second isolator 50 .

[0113] The noise determination circuit 62 performs the above-described noise determination process based on the sensing data acquired by the readout circuit 61 .

[0114] The coordinate calculation circuit 63 performs the above-mentioned coordinate calculation processing based on the sensing data acquired by the readout circuit 61 .

[0115] The storage circuit 64 pre-stores DP control reference data indicating the correspondence between the fundamental frequency of the rectangular wave signal Tx output from the AFE circuit 15 and the resistance value of the digital potentiometer 22. The DP control reference data is, for example, data in the form of a table that shows a one-to-one correspondence between the fundamental frequency of the rectangular wave signal Tx output from the AFE circuit 15 and the resistance value of the digital potentiometer 22.

[0116] The control circuit 60 refers to the DP control reference data held in the storage circuit 64 and outputs a resistance value setting command for setting the resistance value of the digital potentiometer 22 to a resistance value corresponding to the fundamental frequency of the rectangular wave signal Tx output from the AFE circuit 15 .

[0117] The control circuit 60 also has a function of changing the fundamental frequency of the rectangular wave signal Tx output from the AFE circuit 15. When the fundamental frequency of the rectangular wave signal Tx output from the AFE circuit 15 is changed, the control circuit 60 resets the resistance value of the digital potentiometer 22 based on the changed fundamental frequency of the rectangular wave signal Tx.

[0118] Figure 13 This is a schematic diagram showing an example of a connection in a structure in which a touch panel 210 is stacked in addition to a display panel 250. The sensor circuit 40 of the detection device 1 is arranged to overlap with the touch panel 210. The touch panel 210 is a touch detection device that detects an object in contact with a detection surface (hereinafter also referred to as "touch detection"). In the present disclosure, the touch panel 210 performs touch detection using a self-capacitance method or a mutual-capacitance method.

[0119] exist Figure 13 In the device structure shown, the touch panel 210 is provided so as to be sandwiched between the display panel 250 and the sensor circuit 40 .

[0120] Touch panel 210 includes FPC 215. Various circuits related to the operation of touch panel 210 are provided on FPC 215. FPC 215 is connected to FPC 255. FPC 255 is connected to processing device 110. Processing device 110 functions as a host device including sensor circuit 40, touch panel 210, and display panel 250, for example.

[0121] exist Figure 13 In the illustrated configuration, hover detection in the sensor circuit 40 of the detection device 1 utilizes an electric field generated by electrostatic capacitance. Similarly, touch detection in the touch panel 210 utilizes an electric field generated by electrostatic capacitance.

[0122] In such a configuration, there is a possibility that hover detection in the sensor circuit 40 of the detection device 1 and touch detection in the touch panel 210 may interfere with each other. Specifically, for example, if the driving frequency in the self-capacitive hover detection, that is, the fundamental frequency of the rectangular wave signal Tx output from the AFE circuit 15, is the same as the driving frequency in the self-capacitive or mutual-capacitive touch detection, the higher harmonic components (high-frequency noise components) of the rectangular wave signal Tx may be superimposed on the electrodes of the touch panel 210, causing malfunction of the touch detection of the touch panel 210.

[0123] In the present disclosure, the driving frequency for self-capacitive hover detection, that is, the fundamental frequency of the rectangular wave signal Tx output from the AFE circuit 15, can be changed. This prevents malfunctions in touch detection on the touch panel 210. Hereinafter, changing the fundamental frequency of the rectangular wave signal Tx is also referred to as "frequency hopping."

[0124] Figure 14 This is a flowchart illustrating an example of a hovering detection operation in the detection device 1. When power is supplied from the power supply circuit 11 and the sensing operation of the detection device 1 is started (step S1), the detection device 1 performs a baseline scan to obtain a detection signal Rx while the object is not approaching the sensor circuit 40 (step S2).

[0125] After performing the baseline scan, the detection device 1 performs normal hover detection (sensing) (step S3). The control circuit 60 performs the aforementioned noise determination and coordinate calculation based on the difference between the detection signal Rx obtained through the baseline scan (step S2) and the detection signal Rx obtained through sensing (step S3). More specifically, the noise determination circuit 62 performs the noise determination (step S4) based on the difference between the detection signal Rx obtained through the baseline scan (step S2) and the detection signal Rx obtained through sensing (step S3).

[0126] Furthermore, the coordinate operation circuit 63 performs coordinate operation processing (step S5 ) based on the difference between the detection signal Rx acquired by the baseline scanning (step S2 ) and the detection signal Rx acquired by the sensing (step S3 ).

[0127] It should be pointed out that in Figure 14 , an example is shown in which the coordinate calculation processing (step S5) is performed after the noise determination processing (step S4), but it is also possible to perform the noise determination processing (step S4) after the coordinate calculation processing (step S5), or to perform the noise determination processing (step S4) and the coordinate calculation processing (step S5) in parallel.

[0128] Next, the control circuit 60 determines whether the condition for performing the frequency hopping (hereinafter also referred to as "frequency hopping condition") is satisfied (step S6). Specifically, the control circuit 60 determines whether the frequency hopping condition is satisfied. Figure 13 The processing device 110 connected to the FPC 255 shown inputs a signal including a frequency hopping instruction instructing the detection device 1 to perform frequency hopping.

[0129] It should be noted that the frequency hopping conditions are not limited to those described above. For example, the processing device 110 may obtain the driving frequency of the detection device 1 and the driving frequency of the touch panel 210, and determine that the frequency hopping condition has been met if the two frequencies are the same. Alternatively, the control circuit 60 of the detection device 1 may obtain the driving frequency of the touch panel 210, and determine that the frequency hopping condition has been met if the frequency is the same as the frequency of the rectangular wave signal Tx. Alternatively, the control circuit 60 may determine whether the frequency hopping condition has been met.

[0130] When the frequency hopping condition is not satisfied (step S6: No), the process proceeds to step S9.

[0131] If the frequency hopping condition is met (step S6: Yes), the control circuit 60 sets the resistance value of the digital potentiometer 22 to a value corresponding to the frequency of the frequency-hopped rectangular wave signal Tx (step S7). Specifically, the control circuit 60 sets the resistance value of the digital potentiometer 22 corresponding to the frequency of the frequency-hopped rectangular wave signal Tx by referring to, for example, the aforementioned DP control reference data. As a result, the resistance value of the digital potentiometer 22 is controlled to a resistance value corresponding to the frequency-hopped rectangular wave signal Tx.

[0132] Furthermore, the control circuit 60 sets the driving frequency in the hover detection, that is, the basic frequency of the rectangular wave signal Tx output from the AFE circuit 15 , to the frequency after frequency hopping (step S8 ).

[0133] It should be pointed out that in Figure 14, an example is shown of setting the driving frequency (basic frequency of the rectangular wave signal Tx) in the suspension detection (step S8) after setting the resistance value of the digital potentiometer 22 (step S7), but it is also possible to set the resistance value of the digital potentiometer 22 (step S7) after setting the driving frequency (basic frequency of the rectangular wave signal Tx) in the suspension detection (step S8), or to perform the setting of the resistance value of the digital potentiometer 22 (step S7) and the setting of the driving frequency (basic frequency of the rectangular wave signal Tx) in the suspension detection (step S8) in parallel.

[0134] If the sensing operation of detection device 1 is completed (step S9: Yes), detection device 1 ends the hovering detection operation. Examples of cases where the sensing operation ends include when power is no longer supplied from power supply circuit 11 or when a command to end the sensing operation is output from processing device 110 to detection device 1. If the sensing operation of detection device 1 is not completed (step S9: No), the operations from step S3 onwards are repeated.

[0135] Figure 15 This is a timing diagram showing an example of the process of the detection device 1 capable of frequency hopping. The suspension detection action in the detection device 1 determines the process of the processing in units of repetition period Cy. First, a clock signal (V-Sync) indicating the start of the repetition period Cy is output at a predetermined period. Figure 15 The clock signal is output at timings T1 and T2. The following describes the flow of operations within the repetition period Cy starting at timing T1.

[0136] Starting from timing T1, a sensing operation (Sensing) corresponding to step S3 is performed in a period Pe1 from timing T1 to the start of period Pe2 when an interrupt signal (IRQ) indicating the end of the sensing operation is generated.

[0137] During the period from the end point of the period Pe2 to the timing T2, the periods Pe3, Pe4, Pe5, Pe6, and Pe7 occur in sequence.

[0138] The period Pe3 is a period for reading (AFERead) the sensing data output from the AFE circuit 15 via the second isolator 50 .

[0139] The period Pe4 is a period in which the noise determination process corresponding to the above-mentioned step S4 and the coordinate calculation process corresponding to the above-mentioned step S5 are executed in parallel.

[0140] The period Pe5 is a period for reflecting the resistance value corresponding to the fundamental frequency of the rectangular wave signal Tx after frequency hopping on the command output of the digital potentiometer 22 (writing information) when frequency hopping is performed.

[0141] The period Pe6 is a period for outputting a command to the AFE circuit 15 (writing information) for setting the basic frequency of the rectangular wave signal Tx to the frequency after frequency hopping when frequency hopping is performed.

[0142] The period Pe7 is a blank period from the end of the period Pe6 to the timing T2.

[0143] Starting from the timing T2, the above-mentioned periods Pe1, ..., Pe7 are repeated again. Thereafter, every time a clock signal (V-Sync) indicating the start of the repetition period Cy is output at a predetermined cycle, the above-mentioned periods Pe1, ..., Pe7 are repeated again.

[0144] It should be noted that the fundamental frequency of the rectangular wave signal Tx before and after the frequency hopping change is within the frequency setting range of the rectangular wave signal Tx in the AFE circuit 15 (e.g., 140 kHz to 200 kHz). It should be noted that, as described above, the frequency setting range of the rectangular wave signal Tx in the AFE circuit 15 (140 kHz to 200 kHz) is merely an example and is not intended to be limiting.

[0145] As described above, in the present disclosure, signals between the AFE circuit 15 and the control circuit 60 are transmitted, for example, via SPI (Serial Peripheral Interface), a clock-synchronized serial interface. Furthermore, in the present disclosure, signals between the control circuit 60 and the processing device 110 are transmitted, for example, via USB.

[0146] like Figure 5 As shown, the embodiment has a configuration in which the second isolator 50 is provided on the signal transmission path between the AFE circuit 15 and the control circuit 60. Therefore, there is a possibility that the communication speed between the AFE circuit 15 and the control circuit 60 is limited.

[0147] Specifically, the practical communication speed of a general-purpose photocoupler, which is typically used as the second isolator 50, is approximately several kbps. Furthermore, even when using a magnetically isolated digital isolator capable of higher-speed communication, a propagation delay of several nanoseconds may occur, necessitating a clock input delay.

[0148] Below, refer to Figure 16 and Figure 17 The structure according to the first embodiment will be described. Figure 16This is a diagram showing an example of the block configuration of the detection device 1 according to the first embodiment. Figure 17 FIG. 1 is a diagram showing an example of a functional circuit block structure of the detection device 1 according to the first embodiment. Figure 5 and Figure 12 In the illustrated embodiments, the same components are denoted by the same reference numerals, and detailed description thereof may be omitted.

[0149] exist Figure 16 and Figure 17 In the structure of the embodiment 1 shown in FIG. 1 , the control circuit 60 is included in the detection block 10. Figure 16 and Figure 17 In the structure shown, the control circuit 60 operates with the second reference potential GND2 generated by the reference potential generating circuit 20 as the ground potential. More specifically, Figure 17 The readout circuit 61 , noise determination circuit 62 , coordinate calculation circuit 63 and storage circuit 64 of the control circuit 60 shown operate with the second reference potential GND2 as the ground potential. The second reference potential GND2 is a periodically varying potential generated by the reference potential generation circuit 20 .

[0150] In addition, Figure 16 and Figure 17 In the configuration according to the illustrated embodiment 1, the power supply circuit 11a includes a linear regulator (LDO) 18. The linear regulator 18 is included in the detection block 10a.

[0151] The linear regulator 18 is interposed between the isolated DC-DC converter 12 and the control circuit 60 and adjusts the output voltage to the control circuit 60 to a more appropriate voltage. The linear regulator 18 outputs a voltage required as a power supply for the control circuit 60 using the second reference potential GND2 as a ground potential.

[0152] The AFE circuit 15 transmits signals such as sensing data and various control commands to the control circuit 60 . Specifically, for example, the AFE circuit 15 outputs sensing data indicating a result of hovering detection to the control circuit 60 .

[0153] As described above, in the configuration according to Embodiment 1, the control circuit 60 operates with the second reference potential GND2 as the ground potential, similarly to the AFE circuit 15. Signals such as various information related to the sensed data and control commands are transmitted between the control circuit 60 and the processing device 110 via the second isolator 51.

[0154] The second isolator 51 performs insulation between the processing device 110 and the detection block 10 a and transmits signals between the control circuit 60 and the processing device 110 .

[0155] Specifically, the electrical signal output from the terminal on the processing device 110 side of the second isolator 51 having the first reference potential GND1 (fixed potential) as the ground potential is synchronized with the electrical signal output from the detection block 10a having the second reference potential GND2 as the ground potential.

[0156] Furthermore, the electrical signal output from the terminal on the detection block 10a side of the second isolator 51 having the second reference potential GND2 as the ground potential is synchronized with the electrical signal output from the processing device 110 having the first reference potential GND1 (fixed potential) as the ground potential.

[0157] In the second isolator 51, signal transmission between the control circuit 60 and the processing device 110 is performed using magnetic insulation, based on the same principle as the isolated DC-DC converter 12. The second isolator 51 performs magnetically isolated signal transmission between the coil on the processing device 110 side and the coil on the control circuit 60 side. A magnetically isolated digital isolator is exemplified as the second isolator 51.

[0158] The second isolator 51 enables bidirectional transmission of signals from the control circuit 60 to the processing device 110 and vice versa. More specifically, when signals between the control circuit 60 and the processing device 110 are transmitted via USB, the second isolator 51 is a USB isolator that electrically isolates the circuit on the USB host side (the processing device 110) from the circuit on the USB device side (the control circuit 60).

[0159] The second isolator (USB isolator) 51 includes a plurality of magnetic coupling circuits 51a and 51b. Figure 16 In the structure shown, the magnetic coupling circuit 51a is provided between the signal line D1+ on the processing device 110 side and the signal line D2+ on the control circuit 60 side. The magnetic coupling circuit 51a performs magnetically insulated signal transmission between the coil on the processing device 110 side and the coil on the control circuit 60 side. Figure 16 In the illustrated configuration, magnetic coupling circuit 51b is provided between signal line D1- on the processing device 110 side and signal line D2- on the control circuit 60 side. Magnetic coupling circuit 51b enables magnetically isolated signal transmission between the coil on the processing device 110 side and the coil on the control circuit 60 side.

[0160] It should be noted that when signals between the control circuit 60 and the processing device 110 are transmitted via USB, the USB may also include multiple transmission lines and reception lines in addition to signal lines. In this case, the second isolator 51 only needs to include multiple magnetic coupling circuits corresponding to the signal lines, transmission lines, and reception lines.

[0161] In the configuration of the detection device 1 according to the first embodiment described above, the control circuit 60 is included in the detection block 10a along with the sensor circuit 40 and the AFE circuit 15. Therefore, the transmission path for the sensed data, various control commands, and other signals transmitted between the AFE circuit 15 and the control circuit 60 is not electrically connected via a photocoupler or digital isolator. This reduces the speed limit of the communication between the AFE circuit 15 and the control circuit 60.

[0162] More specifically, for example, Figure 15 In the timing diagram shown, the period Pe3 during which the sensing data output from the AFE circuit 15 is read (AFE Read) can be shortened. This, for example, can extend the sensing period Pe1, thereby improving the SNR. Furthermore, for example, the period Cy during which the hover detection operation is repeated in the detection device 1 can be shortened, thereby improving the frame rate.

[0163] (Implementation Method 2)

[0164] Figure 18 This is a diagram showing an example of a block configuration of a detection device according to a modification of the embodiment. Figure 19 1 is a diagram showing an example of a functional circuit block configuration of a detection device according to a modification of the embodiment. Components identical to those in the embodiment and embodiment 1 are denoted by the same reference numerals, and detailed descriptions thereof may be omitted.

[0165] exist Figure 18 and Figure 19 In the structure of the modified example of the embodiment shown, Figure 5 and Figure 12 The structure of the embodiment shown is a mode including a plurality of first AFE circuits 15a and second AFE circuits 15b. Figure 18 and Figure 19 In the structure of the modified example of the embodiment shown, the first AFE circuit 15a is connected to half of the sensor electrodes 42 among the sensor electrodes 421, ..., 42n, and the second AFE circuit 15b is connected to half of the sensor electrodes 42 among the sensor electrodes 421, ..., 42n that are not connected to the first AFE circuit 15a.

[0166] In the configuration of the modification of the embodiment, an embodiment is exemplified in which the first isolators 16 a and 16 b and the second isolators 50 a and 50 b are provided corresponding to the plurality of first AFE circuits 15 a and the second AFE circuits 15 b .

[0167] In addition, in the configuration of the modified example of the embodiment, an analog switch circuit (ASW) 17 is provided for appropriately selecting the rectangular wave signal Tx outputted from each of the plurality of first AFE circuits 15 a and the second AFE circuits 15 b .

[0168] In the configuration of the modified example of the embodiment, the rectangular wave signal Tx output from the first AFE circuit 15 a is transmitted through the first isolator 16 a and is output to the reference potential generating circuit 20 .

[0169] The first isolator 16 a performs insulation between the reference potential generating circuit 20 and the detection block 10 b and transmits the rectangular wave signal Tx output from the first AFE circuit 15 a .

[0170] Specifically, the rectangular wave signal output from the terminal on the reference potential generating circuit 20 side of the first isolator 16 having the first reference potential GND1 (fixed potential) as the ground potential is synchronized with the rectangular wave signal Tx output from the first AFE circuit 15a having the second reference potential GND2 as the ground potential.

[0171] In addition, in the configuration of the modified example of the embodiment, the rectangular wave signal Tx output from the second AFE circuit 15 b is transmitted through the first isolator 16 b and is output to the reference potential generating circuit 20 .

[0172] The first isolator 16 b performs insulation between the reference potential generating circuit 20 and the detection block 10 b and transmits the rectangular wave signal Tx output from the second AFE circuit 15 b .

[0173] Specifically, the rectangular wave signal output from the terminal on the reference potential generating circuit 20 side of the first isolator 16b having the first reference potential GND1 (fixed potential) as the ground potential is synchronized with the rectangular wave signal Tx output from the second AFE circuit 15b having the second reference potential GND2 as the ground potential.

[0174] In the configuration of the modified embodiment, the analog switch circuit 17 operates with the fixed first reference potential GND1 as the ground potential. Note that, in a configuration where the plurality of first and second AFE circuits 15a and 15b operate synchronously, the analog switch circuit 17 may not be provided.

[0175] Signals such as sensing data and various control commands are transmitted between the first AFE circuit 15 a and the control circuit 60 via the second isolator 50 a .

[0176] The second isolator 50 a performs insulation between the control circuit 60 and the detection block 10 b and transmits signals between the first AFE circuit 15 a and the control circuit 60 .

[0177] Specifically, the electric signal output from the terminal on the control circuit 60 side of the second isolator 50a having the first reference potential GND1 (fixed potential) as the ground potential is synchronized with the electric signal output from the detection block 10b having the second reference potential GND2 as the ground potential.

[0178] Furthermore, the electrical signal output from the terminal on the detection block 10b side of the second isolator 50a having the second reference potential GND2 as the ground potential is synchronized with the electrical signal output from the control circuit 60 having the first reference potential GND1 (fixed potential) as the ground potential.

[0179] Examples of the second isolator 50a include an optically isolated photocoupler or a magnetically isolated digital isolator. The second isolator 50a is capable of bidirectional transmission of output from the control circuit 60 to the detection block 10b and vice versa.

[0180] Signals such as sensing data and various control commands are transmitted between the second AFE circuit 15 b and the control circuit 60 via the second isolator 50 b .

[0181] The second isolator 50 b performs insulation between the control circuit 60 and the detection block 10 b and transmits signals between the second AFE circuit 15 b and the control circuit 60 .

[0182] Specifically, the electric signal output from the terminal on the control circuit 60 side of the second isolator 50b having the first reference potential GND1 (fixed potential) as the ground potential is synchronized with the electric signal output from the detection block 10b having the second reference potential GND2 as the ground potential.

[0183] Furthermore, the electric signal output from the terminal on the detection block 10b side of the second isolator 50b having the second reference potential GND2 as the ground potential is synchronized with the electric signal output from the control circuit 60 having the first reference potential GND1 (fixed potential) as the ground potential.

[0184] Examples of the second isolator 50 b include an optically isolated photocoupler or a magnetically isolated digital isolator. The second isolator 50 b is capable of bidirectional transmission of output from the control circuit 60 to the detection block 10 b and vice versa.

[0185] The control circuit 60 and the processing device 110 transmit signals such as various information related to the sensing data and control instructions.

[0186] As described above, in the configuration of the modified example of the embodiment, as the signal transmitted inside and outside the detection block 10b increases, as shown in FIG. Figure 18 and Figure 19 As shown, the number of first isolators 16a, 16b and second isolators 50a, 50b is increased.

[0187] Below, refer to Figure 20 and Figure 21 The structure involved in the second embodiment is described. Figure 20 This is a diagram showing an example of a block structure of a detection device according to the second embodiment. Figure 21 This diagram shows an example of a functional circuit block configuration of a detection device according to Embodiment 2. Components identical to those in the embodiment, Embodiment 1, and the modified embodiment are denoted by the same reference numerals, and detailed descriptions thereof may be omitted.

[0188] exist Figure 20 and Figure 21 In the structure of the second embodiment shown in FIG. 1 , the analog switch circuit 17 is included in the detection block 10 c together with the control circuit 60. Figure 20 and Figure 21 In the illustrated configuration, the analog switch circuit 17 and the control circuit 60 operate using the second reference potential GND2 generated by the reference potential generating circuit 20 as the ground potential.

[0189] More specifically, the analog switch circuit 17 and Figure 21 The readout circuit 61 , noise determination circuit 62 , coordinate calculation circuit 63 , and storage circuit 64 of the control circuit 60 shown operate with the second reference potential GND2 as the ground potential. The second reference potential GND2 is a periodically varying potential generated by the reference potential generation circuit 20 .

[0190] In the configuration according to Embodiment 2, the first and second AFE circuits 15a, 15b transmit signals such as sensing data and various control commands to the control circuit 60. Specifically, for example, the first and second AFE circuits 15a, 15b output sensing data indicating the results of hover detection to the control circuit 60.

[0191] In the configuration according to the second embodiment, signals such as various information related to the sensing data and control commands are transmitted between the control circuit 60 and the processing device 110 via the second isolator 51 .

[0192] As the second isolator 51, a magnetically insulated digital isolator is exemplified, similar to the configuration of Embodiment 1. More specifically, in a configuration in which signals between the control circuit 60 and the processing device 110 are transmitted via USB, the second isolator 51 is a USB isolator that electrically isolates the circuit on the USB host side (the processing device 110) from the circuit on the USB device side (the control circuit 60).

[0193] In the configuration of the detection device 1 according to the second embodiment described above, the control circuit 60 is included in the detection block 10c along with the sensor circuit 40, the first AFE circuit 15a, and the second AFE circuit 15b. Therefore, the transmission paths for sensing data, various control commands, and other signals transmitted between the first and second AFE circuits 15a, 15b and the control circuit 60 are not electrically connected via photocouplers or digital isolators. This, similar to the configuration according to the first embodiment, can suppress speed limitations on the communication between the first and second AFE circuits 15a, 15b and the control circuit 60.

[0194] More specifically, for example, Figure 15 In the timing diagram shown, the period Pe3 during which sensing data output from the first AFE circuit 15a and the second AFE circuit 15b is read (AFE Read) can be shortened. This, similar to the configuration of Embodiment 1, can extend the sensing period Pe1, improving the SNR. Furthermore, for example, the repetition period Cy of the hover detection operation in the detection device 1 can be shortened, increasing the frame rate.

[0195] Furthermore, in the configuration of the modified example of the aforementioned embodiment, the number of isolators (first isolators 16a, 16b and second isolators 50a, 50b) increases as the number of signals transmitted inside and outside the detection block 10b increases. In contrast, the configuration of the detection device 1 according to the second embodiment suppresses the increase in signals transmitted inside and outside the detection block 10c, and consequently, suppresses the increase in isolators. This prevents the cost and size increase caused by the addition of isolators.

[0196] It should be noted that, in the above embodiment, a configuration is shown in which the reference potential generating circuit 20 includes the digital potentiometer 22. However, if radiation noise can be suppressed using only the low-pass filter 23, a configuration can be adopted in which the digital potentiometer 22 is removed. This can eliminate the need for an isolator (not shown) provided in the transmission path for the resistance value setting command between the control circuit 60 and the digital potentiometer 22.

[0197] While preferred embodiments of the present invention have been described above, the present invention is not limited to such embodiments. The contents disclosed in the embodiments are ultimately merely examples, and various modifications can be made without departing from the gist of the present invention. Appropriate modifications made without departing from the gist of the present invention naturally also fall within the technical scope of the present invention. Various omissions, replacements, and modifications of at least one of the constituent elements can be made without departing from the gist of the above-mentioned embodiments and modifications.

[0198] Description of Reference Numerals

[0199] 1 Detection device; 10, 10a, 10b, 10c detection block; 11, 11a power supply circuit; 12 isolated DC-DC converter; 13 linear regulator (LDO); 14 linear regulator (LDO); 15 AFE circuit; 15a first AFE circuit; 15b second AFE circuit; 16, 16a, 16b first isolator; 17 analog switch circuit; 18 linear regulator (LDO); 20 reference potential generation circuit; 22 digital potentiometer (DP); 23 low-pass filter (LPF); 24 amplifier circuit (AMP); 40 sensor circuit; 41 peripheral electrode (second electrode); 42 sensor electrode (first electrode); 43 substrate; 44 shield electrode; 50, 50a, 50b Second isolator; 51 second isolator (USB isolator); 51a, 51b magnetic coupling circuit; 60 control circuit (MCU); 61 readout circuit; 62 noise judgment circuit; 63 coordinate calculation circuit; 64 storage circuit; 110 processing device (external processing device, HOST); 151 readout circuit; 152 ADC circuit; 153 DSP circuit; 210 touch panel; 250 display panel; 260 adhesive layer; 270 covering component; 280 adhesive layer; BE peripheral area; D+, D1+, D2+, D-, D1-, D2- signal lines; GND1 first reference potential; GND2 second reference potential; Rx detection signal; SA detection area; Tx rectangular wave signal; VBUS power line.

Claims

1. A detection device comprising: a sensor circuit having a detection area; An AFE circuit, which obtains a detection signal from the sensor circuit; A control circuit for controlling the AFE circuit; a reference potential generating circuit that operates with a first reference potential as a ground potential and generates a second reference potential synchronized with the rectangular wave signal output from the AFE circuit, wherein the first reference potential is a fixed potential; a first isolator provided in a transmission path of the rectangular wave signal between the AFE circuit and the reference potential generating circuit; as well as A second isolator is provided in a signal transmission path between an external processing device using the first reference potential as a ground potential and the control circuit, The AFE circuit and the control circuit operate with the second reference potential as a ground potential, and a signal transmission path between the AFE circuit and the control circuit is electrically connected to each other.

2. The detection device according to claim 1, wherein The first isolator is a photocoupler.

3. The detection device according to claim 1, wherein: The second isolator is a digital isolator using magnetic insulation.

4. The detection device according to claim 1, wherein: The detection device includes a power supply circuit that supplies power to the AFE circuit and the control circuit. The power supply circuit includes an isolated DC-DC converter provided in a power supply path from outside having the first reference potential as a ground potential.

5. The detection device according to claim 1, wherein: The detection device includes a plurality of the AFE circuits.

6. The detection device according to any one of claims 1 to 5, wherein: The sensor circuit has: a plurality of first electrodes, disposed in the detection area; as well as The second electrode is provided around the detection area and is supplied with the second reference potential. The AFE circuit supplies a driving signal to the first electrode, and acquires an electric signal generated at the first electrode and outputs it as the detection signal.

7. The detection device according to claim 6, wherein: The sensor circuit further includes a shield electrode provided across a substrate from the plurality of first electrodes and the second electrode.

8. The detection device according to claim 7, wherein: The AFE circuit amplifies the drive signal to generate the rectangular wave signal, and outputs the rectangular wave signal to the reference potential generating circuit via the first isolator.

9. The detection device according to claim 8, wherein: The reference potential generating circuit generates a second reference potential in a substantially rectangular wave shape from which high-frequency components are removed.

10. The detection device according to claim 8, wherein: The reference potential generating circuit generates a substantially sinusoidal second reference potential.

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