Detection device

Abstract

Provided is a detection device capable of improving detection sensitivity. A detection device according to the present invention comprises: a detection region for detecting capacitance; a plurality of sensor electrodes arranged in a matrix in the detection region; and at least one planar conductive layer to which a predetermined reference potential is supplied. Among the plurality of sensor electrodes, sensor electrodes superposed on the conductive layer are high-parasitic capacitance sensor electrodes, and sensor electrodes adjacent to the high-parasitic capacitance sensor electrodes among the sensor electrodes are high-sensitivity sensor electrodes for detecting a main electric field.

Description

Detection Device

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

[0002] A capacitance-based detection device that detects the proximity of an object by detecting a change in capacitance is known (see, for example, Patent Document 1). Such a detection device having a so-called hover detection (proximity detection) function is provided with a plurality of detection electrodes and a shield electrode that is arranged around a detection area where the plurality of detection electrodes are provided, and an electrical signal is applied to the shield electrode.

[0003] U.S. Patent No. 9,151,792

[0004] However, in a capacitance detection device, if an insulator is placed in a position overlapping the detection area, the detection sensitivity may decrease, making it difficult to detect an object to be detected that is on the insulator.

[0005] An object of the present disclosure is to provide a detection device that can improve detection sensitivity.

[0006] A detection device according to one aspect of the present disclosure comprises a detection area for detecting capacitance, a plurality of sensor electrodes arranged in a matrix in the detection area, and at least one planar conductive layer to which a predetermined reference potential is supplied, wherein the sensor electrodes among the plurality of sensor electrodes that overlap with the conductive layer are high-parasitic capacitance sensor electrodes, and the sensor electrodes among the sensor electrodes adjacent to the high-parasitic capacitance sensor electrodes are high-sensitivity sensor electrodes that detect a main electric field.

[0007] FIG. 1 is a perspective view showing a schematic configuration of a detection device according to an embodiment. FIG. 2 is a diagram showing the main configuration of a detection device according to an embodiment. FIG. 3 is a plan view showing a schematic configuration of a detection device according to embodiment 1. FIG. 4 is a schematic cross-sectional view showing an example of a schematic configuration of a detection device according to embodiment 1. FIG. 5 is a schematic diagram showing an example of a connection between a sensor main body and a processing device of a detection device according to an embodiment. FIG. 6 is a diagram showing an example of a block configuration of a detection device according to an embodiment. FIG. 7 is a diagram showing an example of a configuration of a drive signal generation circuit according to embodiment 1. FIG. 8 is a diagram showing an example of a functional circuit block configuration of a detection device according to embodiment 1. FIG. 9 is a schematic diagram showing the flow of electricity in an electric field generated when the potential of a peripheral electrode is higher than the potential of a sensor electrode. FIG. 10 is a schematic diagram showing the flow of electricity in an electric field generated when the potential of a peripheral electrode is lower than the potential of a sensor electrode. FIG. 11 is a main flowchart showing an example of a detection process in the detection device. FIG. 12 is a sub-flowchart showing an example of a baseline setting process. FIG. 13 is a sub-flowchart showing an example of a detection mode determination process. FIG. 14 is a plan view for explaining an example of a conductive layer in a detection region of a detection device according to embodiment 1. FIG. 15 is a plan view illustrating the conductive layer of the detection device according to embodiment 1 in FIG. 14 . FIG. 16 is a plan view illustrating another example of the conductive layer in the detection region of the detection device according to embodiment 1. FIG. 17 is a plan view illustrating the conductive layer of the detection device according to embodiment 1 in FIG. 16 . FIG. 18 is a schematic diagram illustrating the flow of an electric field in the electric field generated in the conductive layer in FIGS. 15 and 17 . FIG. 19 is an explanatory diagram illustrating the relationship between the ratio of the area of ​​a portion of the conductive layer overlapping the sensor electrode to the area of ​​the sensor electrode and the SNR, comparing conductive layers having square shapes and different areas. FIG. 20 is an explanatory diagram illustrating the relationship between the ratio of the area of ​​a portion of the conductive layer overlapping the sensor electrode to the area of ​​the sensor electrode and the SNR, comparing conductive layers having the same length but different widths. FIG. 21 is a plan view illustrating a schematic configuration of a detection device according to embodiment 2. FIG. 22 is a schematic cross-sectional view illustrating an example of the schematic configuration of a detection device according to embodiment 2. FIG. 23 is a plan view illustrating an example of the conductive layer in the detection region of the detection device according to embodiment 2.FIG. 24 is a plan view illustrating a conductive layer of a detection device according to embodiment 2. FIG. 25 is a schematic diagram illustrating the flow of an electric field in an electric field generated in the conductive layer according to embodiment 2. FIG. 26 is an explanatory diagram illustrating the relationship between the ratio of the area of ​​a portion of the conductive layer overlapping the sensor electrode to the area of ​​the sensor electrode and the SNR in a detection device according to embodiment 2. FIG. 27 is a plan view illustrating an example of a conductive layer in a detection region of a detection device according to a modified embodiment of embodiment 2. FIG. 28 is a plan view illustrating a conductive layer of a detection device according to a modified embodiment of embodiment 2. FIG. 29 is an explanatory diagram illustrating the relationship between the ratio of the area of ​​a portion of the conductive layer overlapping the sensor electrode to the area of ​​the sensor electrode and the SNR in a detection device according to a modified embodiment of embodiment 2. FIG. 30 is a plan view illustrating a schematic configuration of a detection device according to embodiment 3. FIG. 31 is a schematic cross-sectional view illustrating an example of the schematic configuration of a detection device according to embodiment 3. FIG. 32 is a plan view illustrating an example of a conductive layer in the detection region of a detection device according to embodiment 3. FIG. 33 is a schematic diagram illustrating the flow of an electric field in an electric field generated in the conductive layer according to embodiment 3. Fig. 34 is an explanatory diagram showing the relationship between the ratio of the area of ​​the conductive layer overlapping the sensor electrode to the area of ​​the sensor electrode and the SNR in the detection device according to embodiment 3. Fig. 35 is a schematic cross-sectional view showing another example of the position of the conductive layer according to embodiment 3.

[0008] Modes (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the contents described in the following embodiments. Furthermore, the components described below include those that can be easily imagined by a person skilled in the art and those that are substantially identical. Furthermore, the components described below can be combined as appropriate. Furthermore, the disclosure is merely an example, and appropriate modifications that a person skilled in the art can easily conceive while maintaining the gist of the invention are naturally included within the scope of the present invention. Furthermore, for clarity of explanation, the drawings may show the width, thickness, shape, etc. of each part schematically compared to the actual embodiment. However, these are merely examples and are not intended to limit the interpretation of the present invention. Furthermore, in this specification and each figure, elements similar to those described above with reference to the previous figures may be designated by the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0009] In this specification and claims, when expressing an aspect of placing another structure on top of a certain structure, the term "on top" is used, unless otherwise specified, to include both a case in which another structure is placed directly on top of a certain structure so as to be in contact with the certain structure, and a case in which another structure is placed above a certain structure via yet another structure.

[0010] 1 is a perspective view showing a schematic configuration of a detection device according to an embodiment. As shown in Fig. 1, the detection device 1 includes a cover member 270 and a sensor main body 40 provided on the back surface of the cover member 270.

[0011] The cover member 270 is a plate-shaped member having dielectric properties and may be made of, for example, wood, acrylic resin, or the like.

[0012] The object to be detected 101 is a member having a higher dielectric constant than air. The object to be detected 101 may be made of, for example, wood, marble, or glass. In this embodiment, the object to be detected 101 is described as being made of wood. Wood has anisotropy, meaning that detection sensitivity varies depending on the direction of the wood grain. The dielectric constant of wood is 2.0 or more and 6.0 or less. The dielectric constant of marble is 3.5 or more and 9.3 or less, and the dielectric constant of glass is 3.7 or more and 10.0 or less.

[0013] 2 is a diagram showing the main configuration of the detection device 1 according to the embodiment. As shown in FIG. 2, the detection device 1 includes a sensor main body 40 and a detection circuit 2.

[0014] The sensor main body 40 has a plurality of sensor electrodes (first electrodes) 42 and a peripheral electrode (second electrode) 41 provided on a sensor substrate 15. The detection device 1 is a hover detection device that detects the position and movement of the detection target 101 (hereinafter also referred to as "hover detection") without contacting the detection surface of the sensor main body 40. In this embodiment, the detection device 1 performs hover detection using a self-capacitance method.

[0015] The sensor body 40 has a detection area SA and a peripheral area BE outside the detection area SA. The detection area SA is an area where the sensor electrodes 42 are provided and is an area for detecting an object to be detected that is close to the detection surface. The peripheral area BE is an area outside the detection area SA where the sensor electrodes 42 are not provided and where the peripheral electrodes 41 are provided along the four sides of the detection area SA.

[0016] In the following description, the first direction Dx is a direction in a plane parallel to the sensor substrate 15. The second direction Dy is a direction in a plane parallel to the sensor substrate 15, and is a direction perpendicular to the first direction Dx. The second direction Dy may intersect the first direction Dx without being perpendicular to it. The third direction Dz is a direction perpendicular to the first direction Dx and the second direction Dy, and is a normal direction to the main surface of the sensor substrate 15. Furthermore, "planar view" refers to the positional relationship when viewed from a direction perpendicular to the sensor substrate 15.

[0017] The plurality of sensor electrodes 42 are arranged in a matrix in the detection area SA of the sensor substrate 15. In other words, the plurality of sensor electrodes 42 are arranged side by side in the first direction Dx and the second direction Dy. The plurality of sensor electrodes 42 are each electrically connected to the AFE circuit 16 via wiring (not shown). In this embodiment, the size of the sensor electrode 42 is a square with each side measuring 32 mm.

[0018] The peripheral electrode 41 is disposed to surround the plurality of sensor electrodes 42 provided in the detection area SA.

[0019] A detection circuit 2 is connected to the sensor main body 40. The detection circuit 2 drives each sensor electrode 42 and detects capacitance. The detection circuit 2 has a first side 210 along a first direction Dx and a second side 220 along a second direction Dy that intersects with the first side 210. The detection circuit 2 includes an AFE circuit 16 that performs hover detection based on the output of the sensor main body 40, and a control circuit 60 that controls the hover detection operation in the AFE circuit 16. The AFE circuit 16 is, for example, an analog front end (AFE). The control circuit 60 includes, for example, an MCU (Micro Control Unit).

[0020] A processing device (external processing device) 110 is connected to the detection circuit 2. The processing device 110 functions as a host computer (HOST) of the detection device 1 according to the embodiment. The processing device 110 is, for example, a point of sale (POS) cash register terminal, but is not limited thereto and may be any terminal capable of accepting a hover operation in the detection device 1.

[0021] Fig. 3 is a plan view showing a schematic configuration of the detection device according to embodiment 1. Fig. 4 is a schematic cross-sectional view showing an example of the schematic configuration of the detection device according to embodiment 1. Fig. 4 is a cross-sectional view taken along line IV-IV' in Fig. 3 .

[0022] As shown in FIGS. 3 and 4, a planar conductive layer 47 is disposed inside the cover member 270 .

[0023] 4, the cover member 270 has a first cover member 271 and a second cover member 272. The thickness of the first cover member 271 is 3 mm, and the thickness of the second cover member 272 is 9 mm.

[0024] The conductive layer 47 is disposed between the first cover member 271 and the second cover member 272. The conductive layer 47 overlaps at least one sensor electrode 42. A portion of the conductive layer 47 overlaps a portion of the sensor electrode 42, but does not overlap other portions of the sensor electrode 42. The conductive layer 47 is a conductive metal layer, such as a copper foil tape or a metal wire. The conductive layer 47 may also be a conductive pigment.

[0025] 1 and 4 , the surface of the first cover member 271 is exposed, and a plurality of marks MA corresponding to each sensor electrode 42 are provided on the surface of the cover member 270. The detection objects 101 can be provided on each of the marks MA. The marks MA are arranged so as to overlap the sensor electrodes 42.

[0026] The mark MA is, for example, a button that reacts to the detection object 101, a recess in which the detection object 101 can be placed, or a recess in which the detection object 101 can be slid.

[0027] The conductive layer 47 includes a conductive layer 471 and a conductive layer 472. The conductive layer 47 is adjacent to the mark MA and overlaps a part of the sensor electrode 42.

[0028] The conductive layer 471 is connected to a lead-out line L1 extending in the second direction Dy, and the conductive layer 472 is connected to a lead-out line L2 extending in the first direction Dx. The lead-out lines L1 and L2 are each connected to a first reference potential GND1 (see FIG. 6 described later). The lead-out lines L1 and L2 supply the first reference potential GND1 to the conductive layers 471 and 472, respectively.

[0029] As shown in FIG. 4, the detection device 1 includes a shield layer 14, a sensor substrate 15, a peripheral electrode 41 (FIG. 3), a sensor electrode 42, and a cover member 270.

[0030] The sensor substrate 15 is a light-transmitting substrate made of glass, resin, or the like. A plurality of sensor electrodes 42 are formed on the sensor substrate 15, and the peripheral electrodes 41 and the sensor electrodes 42 are covered with a protective layer OC, which flattens the surface and protects the peripheral electrodes 41 and the sensor electrodes 42. The protective layer OC is a light-transmitting resin, such as an acrylic resin. The protective layer OC may be an inorganic resin, not just an organic resin, or a laminate of an organic resin and an inorganic resin.

[0031] The shield layer 14 is laminated on the detection device 1. The shield layer 14 is a conductive layer of a metallic film that has a metallic luster and is translucent. The material of the shield layer 14 is a metallic material such as Al, Ag, or Mo. The shield layer 14 can block electromagnetic waves that reach the detection device 1 from the rear surface of the detection device 1. Furthermore, the shield layer 14 overlaps with the detection area AA of the sensor main body 40 in the third direction Dz and has the same area as the detection area AA. Therefore, the shield layer 14 has a larger area than the sensor electrode 42. Note that the shield layer 14 may also have a larger area than the detection area AA.

[0032] The cover member 270 is a protective panel that protects the front surface of the detection device 1. The cover member 270 is stacked on the sensor substrate 15 in a third direction Dz that is perpendicular to the surface of the cover member 270. The sensor substrate 15 is fixed to the cover member 270 via an adhesive layer AT. The adhesive layer AT is a translucent adhesive called OCA (Optical Clear Adhesive). The adhesive layer AT may be a translucent film with double-sided adhesive properties. The upper surface of the cover member 270 is a detection surface for hover detection.

[0033] The peripheral electrodes 41 and the sensor electrodes 42 are provided on the same sensor substrate 15. The sensor substrate 15 is a film-like or plate-like member made of an insulating material, such as a resin film or a glass substrate. The peripheral electrodes 41 and the sensor electrodes 42 are not limited to being provided on the same layer of the sensor substrate 15, but may be provided on different layers of the sensor substrate 15. The sensor electrode 42 is formed of a translucent conductive material such as ITO (indium tin oxide) or IZO (indium zinc oxide). The peripheral electrode 41 may be formed of the same material as the sensor electrode 42, or may be formed of a different metal material from the sensor electrode 42.

[0034] FIG. 5 is a schematic diagram showing an example of connection between the sensor body and the processing device of the detection device according to the embodiment.

[0035] In the so-called on-cell type device configuration shown in Fig. 5, the detection device 1 includes an FPC (Flexible Printed Circuits) 70. The FPC 70 is connected to a PCB (Printed Circuit Board) 46. Various circuits that constitute the detection circuit 2 are mounted on the PCB 46. Fig. 3 illustrates circuits 46a and 46b as examples of the various circuits that constitute the detection circuit 2. The circuits 46a and 46b function as, for example, the AFE circuit 16 and the control circuit 60.

[0036] The PCB 46 is connected to the processing device 110 via a cable 470. The cable 470 has a function of transmitting signals generated between the detection device 1 and the processing device 110. An example of the cable 470 is a USB (Universal Serial Bus) cable.

[0037] FIG. 6 is a diagram illustrating an example of a block configuration of a detection device according to an embodiment.

[0038] As shown in FIG. 6, the detection device 1 includes, in addition to the sensor body 40, the AFE circuit 16, and the control circuit 60 described above, a first power supply circuit 11 (POW1), an isolated DC-DC converter 12, a second power supply circuit 13 (POW2), a drive signal generation circuit 20, a first isolator 51, and a second isolator 52.

[0039] The plurality of sensor electrodes 42 are each connected to the AFE circuit 16. The peripheral electrode 41 and the shield layer 14 function as an active shield whose potential periodically fluctuates in response to changes in the second reference potential GND2 provided by the drive signal generation circuit 20a. The AFE circuit 16 acquires, as a detection signal Rx, an electrical signal corresponding to the self-capacitance generated in each sensor electrode 42.

[0040] The magnitude of the detection signal Rx obtained from each sensor electrode 42 changes depending on the distance between each sensor electrode 42 and a nearby object. Based on the detection signal Rx obtained from each sensor electrode 42, the AFE circuit 16 generates sensing data according to the distance between each sensor electrode 42 and a nearby object, and outputs the sensing data to the control circuit 60.

[0041] The processing device 110, the control circuit 60, the first power supply circuit 11, and the drive signal generation circuit 20 are included in a first reference potential block 3. In the present disclosure, the second power supply circuit 13, the AFE circuit 16, and the sensor main body 40 are included in a second reference potential block 4. The processing device 110, the control circuit 60, the first power supply circuit 11, and the drive signal generation circuit 20 included in the first reference potential block 3 operate using a first reference potential GND1, which is a fixed potential, as a ground potential. The second power supply circuit 13, the AFE circuit 16, and the sensor main body 40 included in the second reference potential block 4 operate using a second reference potential GND2 generated by the drive signal generation circuit 20 as a ground potential.

[0042] The first power supply circuit 11 converts the voltage of the power supplied via the power line VBUS of the USB cable and supplies the converted voltage to the control circuit 60 and the drive signal generation circuit 20 .

[0043] The insulated DC-DC converter 12 provides insulation and power transmission between the processing device 110 and the second power supply circuit 13. The insulated DC-DC converter 12 performs power transmission using a magnetic insulation method.

[0044] In the isolated DC-DC converter 12, power is supplied to the coil on the first reference potential block 3 side via the power line VBUS of the USB cable, causing the coil to generate a magnetic field. The coil on the second reference potential block 4 side is provided within the range of influence of the magnetic field generated by the coil on the first reference potential block 3 side.

[0045] An induced electromotive force is generated in the coil on the second reference potential block 4 side according to the magnetic field generated by the coil on the first reference potential block 3 side. The power generated in the coil on the second reference potential block 4 side is supplied to the second power supply circuit 13.

[0046] The second power supply circuit 13 converts the voltage of the power supplied from the isolated DC-DC converter 12 and supplies the converted voltage to the AFE circuit 16 .

[0047] The AFE circuit 16 generates a rectangular wave signal Tx as a periodically varying potential having a periodic potential variation pattern. The rectangular wave signal Tx includes the fundamental frequency component and harmonic components of the drive signal supplied to the peripheral electrode 41 and the shield electrode 44 of the sensor body 40.

[0048] In addition, the AFE circuit 16 acquires sensing data from the plurality of sensor electrodes 42 and outputs it to the control circuit 60 via the first isolator 51 .

[0049] In the present disclosure, signals between the AFE circuit 16 and the control circuit 60 are transmitted via a serial peripheral interface (SPI), which is a clock-synchronized serial interface. Note that the serial interface for transmitting signals between the AFE circuit 16 and the control circuit 60 is not limited to the SPI.

[0050] The first isolator 51 provides insulation and transmits signals between the control circuit 60 and the AFE circuit 16. Electrical signals input and output via the first isolator 51 are synchronized between the control circuit 60 and the AFE circuit 16.

[0051] The second isolator 52 provides insulation between the AFE circuit 16 and the drive signal generation circuit 20 and transmits the rectangular wave signal Tx. The rectangular wave signal Tx input / output via the second isolator 52 is synchronized between the AFE circuit 16 and the drive signal generation circuit 20.

[0052] The second isolator 52 performs optically isolated signal transmission using, for example, a photocoupler. The signal transmission method between the control circuit 60 and the AFE circuit 16 in the first isolator 51 may be the same as or a different method from that of the second isolator 52. In other words, the first isolator 51 may be, for example, an optically isolated photocoupler or a magnetically isolated digital isolator similar to the isolated DC-DC converter 12.

[0053] The first isolator 51 is capable of bidirectional signal transmission, i.e., signal transmission from the control circuit 60 to the AFE circuit 16 and signal transmission from the AFE circuit 16 to the control circuit 60. In a configuration in which an optically isolated photocoupler is used as the first isolator 51, a photocoupler that transmits signals from the control circuit 60 to the AFE circuit 16 and a photocoupler that transmits signals from the AFE circuit 16 to the control circuit 60 are connected in parallel.

[0054] The control circuit 60 transmits signals such as various information related to sensing data and control commands to and from the processing device 110 .

[0055] 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 16 and the electrical resistance value of a digital potentiometer 22 (see FIG. 7 ), which will be described later, the control circuit 60 outputs an electrical resistance value setting command to the digital potentiometer 22 to set the electrical resistance value of the digital potentiometer 22 to an electrical resistance value corresponding to the fundamental frequency of the rectangular wave signal Tx output from the AFE circuit 16. As a result, the electrical resistance value of the digital potentiometer 22 is controlled to an electrical resistance value corresponding to the fundamental frequency of the rectangular wave signal Tx.

[0056] The control circuit 60 also performs noise determination processing on the sensing data and position determination (coordinate calculation processing) of the detectable object based on the sensing data. The noise determination processing is processing performed to determine the amount of noise components contained in the sensing data. The coordinate calculation processing is processing performed to determine the position of the detectable object adjacent to the sensor main body 40. Specifically, the coordinate calculation processing can derive, for example, the position of the detectable object adjacent to the sensor main body 40 in the first direction Dx, the second direction Dy, and the third direction Dz (see FIG. 1 ). The details of the noise determination processing and the coordinate calculation processing are similar to those well known, and therefore will not be described in detail here.

[0057] In the present disclosure, signals between the control circuit 60 and the processing device 110 are transmitted via a USB 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. Note that the serial interface for transmitting signals between the control circuit 60 and the processing device 110 is not limited to USB.

[0058] In the above-described configuration, the first reference potential block 3, which includes the processing device 110, the control circuit 60, the first power supply circuit 11, and the drive signal generating circuit 20, and the second reference potential block 4, which includes the second power supply circuit 13, the AFE circuit 16, and the sensor main body 40, are electrically insulated via the insulated DC-DC converter 12, the first isolator 51, and the second isolator 52.

[0059] The first reference potential GND1 provided as a ground potential to the first reference potential block 3 is a fixed potential maintained by a large electrode such as a solid electrode, while the second reference potential GND2 provided as a ground potential to the second reference potential block 4 is a periodically varying potential generated by the drive signal generation circuit 20.

[0060] In the detection device 1 according to the present disclosure, the fluctuation period of the periodically fluctuating potential (second reference potential GND2) is the same as the generation period (the rectangular wave period of the rectangular wave signal Tx) of the rectangular wave generated by the AFE circuit 16. In other words, the second reference potential GND2 is a potential that periodically fluctuates in synchronization with the rectangular wave signal Tx generated by the AFE circuit 16.

[0061] 7 is a diagram showing an example of the configuration of a drive signal generation circuit according to embodiment 1. In the configuration according to embodiment 1, a drive signal generation circuit 20 includes an LPF circuit 21, an active filter circuit 23, and an amplifier circuit 24.

[0062] The LPF circuit 21 has a resistive element R instead of a digital potentiometer (DP) 22. The LPF circuit 21 functions as a low-pass filter by an RC circuit configured with the resistive element R and a capacitive element C in the subsequent stage. An intermediate wave signal that has been impedance-converted by a voltage follower circuit connected in the subsequent stage of the RC circuit is output to the active filter circuit 23.

[0063] Here, the digital potentiometer 22 is a digital potentiometer circuit that can adjust the electrical resistance value in response to a command from the control circuit 60. The digital potentiometer 22 is provided on the output transmission path of the rectangular wave signal Tx output from the AFE circuit 16 via the second isolator 52. Hereinafter, the digital potentiometer 22 will also be referred to as the "DP circuit 22."

[0064] The amplifier circuit 24 includes a DP circuit 22 as an input resistor of an inverting amplifier circuit including a negative feedback resistor Rf. The output Vout of the amplifier circuit 24 is expressed by the following equation (1), where the input of the amplifier circuit 24 is Vin. Note that a configuration may also be adopted in which a capacitance element Cf for phase compensation is connected in parallel with the negative feedback resistor Rf.

[0065] Vout=-(Rf / Rdp)×Vin...(1)

[0066] The sine wave signal inverted and amplified by the amplifier circuit 24 undergoes impedance conversion by a voltage follower circuit connected downstream of the inverting amplifier circuit, and is supplied as a drive signal to the peripheral electrode 41 and the shield electrode 44 of the sensor body 40, and is also given as a second reference potential GND2, which is the ground potential of the second reference potential block 4. Depending on the polarity of the sine wave signal, the amplifier circuit 24 may not invert the polarity.

[0067] In the configuration of the drive signal generation circuit 20 according to the first embodiment described above, when the amplitude value Vpp of the drive signal is changed by changing the electrical resistance value of the DP circuit 22, no change in phase occurs in the LPF circuit 21. Therefore, it is possible to suppress a decrease in detection sensitivity caused by a difference in the timing of acquiring sensing data.

[0068] FIG. 8 is a diagram illustrating an example of a functional circuit block configuration of the detection device according to the first embodiment.

[0069] 8, the AFE circuit 16 includes a readout circuit 161, an ADC (Analog Digital Converter) circuit 162, and a DSP (Digital Signal Processor) circuit 163. Each circuit element of the AFE circuit 16 operates using a second reference potential GND2, which is a periodically varying potential generated by the drive signal generation circuit 20, as the ground potential.

[0070] The readout circuit 161 acquires the detection signal Rx from each of the sensor electrodes 42 .

[0071] The ADC circuit 162 converts the detection signal Rx acquired by the readout circuit 161 from an analog signal to a digital signal.

[0072] The DSP circuit 163 performs digital filtering on the digital data converted by the ADC circuit 162 to generate a detection signal Rx.

[0073] The AFE circuit 16 outputs the sensing data generated by the DSP circuit 163 to the control circuit 60 via the first isolator 51 .

[0074] The control circuit 60 includes a read circuit 61, a noise determination circuit 62, a coordinate calculation circuit 63, and a memory circuit 64. Each circuit element of the control circuit 60 operates with a first reference potential GND1, which is a fixed potential, as the ground potential.

[0075] The readout circuit 61 acquires the sensing data output from the AFE circuit 16 via the first isolator 51 .

[0076] The noise determination circuit 62 performs the above-described noise determination process based on the sensing data acquired by the readout circuit 61 .

[0077] The coordinate calculation circuit 63 performs the above-mentioned coordinate calculation process based on the sensing data acquired by the readout circuit 61 .

[0078] The memory circuit 64 stores in advance DP control reference data that indicates the correspondence between the fundamental frequency of the rectangular wave signal Tx output from the AFE circuit 16 and the electrical resistance value of the DP circuit 22. The DP control reference data is, for example, data in the form of a table in which the fundamental frequency of the rectangular wave signal Tx output from the AFE circuit 16 and the electrical resistance value of the DP circuit 22 are associated one-to-one.

[0079] In addition, in the present disclosure, it is assumed that the memory circuitry 64 stores in advance a threshold value used for determining the detection mode in the detection mode setting process described below.

[0080] The control circuit 60 refers to the DP control reference data stored in the memory circuit 64 and outputs an electrical resistance value setting command to set the electrical resistance value of the DP circuit 22 so that the electrical resistance value corresponds to the fundamental frequency of the rectangular wave signal Tx output from the AFE circuit 16.

[0081] The control circuit 60 also has a function of changing the fundamental frequency of the rectangular wave signal Tx output from the AFE circuit 16. When the fundamental frequency of the rectangular wave signal Tx output from the AFE circuit 16 is changed, the control circuit 60 resets the electrical resistance value of the DP circuit 22 in accordance with the changed fundamental frequency of the rectangular wave signal Tx.

[0082] In the present disclosure, the control circuit 60 has a function of changing the fundamental frequency of the square wave signal Tx output from the AFE circuit 16. In the present disclosure, the drive frequency in the self-capacitance hover detection, i.e., the fundamental frequency of the square wave signal Tx output from the AFE circuit 16, can be changed. This makes it possible to suppress the effects of noise. Hereinafter, changing the fundamental frequency of the square wave signal Tx is also referred to as "frequency hopping."

[0083] 9 and 10 are schematic diagrams showing the flow of electricity in an electric field that occurs when the potential of the peripheral electrode is higher than that of the sensor electrode.

[0084] Fig. 9 is a schematic diagram showing the flow of electricity in an electric field that occurs when the potential of the peripheral electrode 41 is higher than the potential of the sensor electrode 42. Fig. 10 is a schematic diagram showing the flow of electricity in an electric field that occurs when the potential of the peripheral electrode 41 is lower than the potential of the sensor electrode 42. The strength of the detection signals obtained from each of the sensor electrodes 42a, 42b, and 42c changes depending on whether an object in proximity to the sensor main body 40 is at position P1 or at position P2.

[0085] 11 is a main flowchart illustrating an example of a detection process in the detection device 1. The detection device 1 performs sensing operation by dynamically switching between a hover detection mode (first detection mode) and a touch detection mode (second detection mode) depending on the maximum value of sensing data acquired in the detection area SA.

[0086] When the sensing operation by the detection device 1 starts (step S1), the detection device 1 sets baselines in both the hover detection mode and the touch detection mode (step S2). Fig. 12 is a sub-flowchart showing an example of the baseline setting process.

[0087] In the baseline setting process (step S2), first, the control circuit 60 sets an electrical resistance value for hover detection in the DP circuit 22 (step S21). The electrical resistance value for hover detection is set to, for example, a value that makes the amplitude value Vpp of the drive signal 6.8 V.

[0088] The AFE circuit 16 acquires detection signals Rx from each sensor electrode 42 when no object to be detected is in proximity to the sensor main body 40, and generates baseline data for hover detection based on the detection signals Rx (step S22).

[0089] Next, the control circuit 60 sets an electrical resistance value for touch detection in the DP circuit 22 (step S23). The electrical resistance value for touch detection is set to, for example, a value that makes the amplitude value Vpp of the drive signal 2.5V.

[0090] The AFE circuit 16 acquires the detection signals Rx from the sensor electrodes 42 when no object to be detected is in proximity to the sensor main body 40, and generates baseline data for touch detection based on the detection signals Rx (step S24).

[0091] After the baseline setting process (step S2) is executed, the process returns to the main flow of the detection process shown in Fig. 11, where the AFE circuit 16 acquires the detection signals Rx from each sensor electrode 42, generates sensing data, and transmits it to the control circuit 60. The control circuit 60 sets the detection mode based on the sensing data transmitted from the AFE circuit 16 (step S3). Fig. 13 is a sub-flowchart showing an example of the detection mode determination process.

[0092] In the detection mode setting process (step S3), the control circuit 60 first determines whether the current detection mode is the hover detection mode or the touch detection mode. More specifically, the control circuit 60 determines whether the current detection mode is the hover detection mode (step S31).

[0093] If the hover detection mode is selected (Step S31: Yes), the control circuit 60 determines whether the maximum value RDHmax of the sensing data (RDH(n), where n is a natural number from 1 to N and N is the number of sensor electrodes in the detection area SA) in the detection area SA is equal to or greater than a predetermined threshold value RDHth (RDHmax≧RDHth, Step S32). The threshold value RDHth is pre-stored in the memory circuit 64.

[0094] If the maximum value RDHmax of the sensing data is less than the threshold value RDHth (step S32; No), the control circuit 60 maintains the hover detection mode. If the maximum value RDHmax of the sensing data is equal to or greater than the threshold value RDHth (step S32; Yes), the control circuit 60 changes the detection mode from the hover detection mode to the touch detection mode (step S33).

[0095] If the touch detection mode is selected (Step S31: No), the control circuit 60 determines whether the maximum value RDTmax of each piece of sensing data (RDT(n), n is a natural number ranging from 1 to N, and N is the number of sensor electrodes in the detection area SA) in the detection area SA is less than a predetermined threshold value RDTth (RDTmax<RDTth, Step S34). The threshold value RDTth is stored in advance in the memory circuit 64.

[0096] If the maximum value RDTmax of the sensing data is equal to or greater than the threshold value RDTth (step S34; No), the control circuit 60 enters the touch detection mode. If the maximum value RDTmax of the sensing data is less than the threshold value RDTth (step S34; Yes), the control circuit 60 changes the detection mode from the touch detection mode to the hover detection mode (step S35).

[0097] As described above, when the detectable object is in contact with the detection surface of the sensor main body 40, the sensing data becomes prominent at the position where the detectable object is in contact with the detection surface of the sensor main body 40. Therefore, by performing threshold judgment on the maximum value of the sensing data, it can be determined whether or not the detectable object has come into contact (touched) with the detection surface of the sensor main body 40.

[0098] The control circuit 60 sets the electrical resistance value of the DP circuit 22 so that the amplitude value Vpp of the drive signal is a value corresponding to the detection mode set in the detection mode setting process (step S3). Specifically, when the hover detection mode is set in the detection mode setting process (step S3), the control circuit 60 sets the electrical resistance value of the DP circuit 22 so that the amplitude value Vpp of the drive signal is a first amplitude value (e.g., 6.8 V). When the touch detection mode is set in the detection mode setting process (step S3), the control circuit 60 sets the electrical resistance value of the DP circuit 22 so that the amplitude value Vpp of the drive signal is a second amplitude value (e.g., 2.5 V) smaller than the first amplitude value.

[0099] 11 , the detection device 1 performs a normal sensing operation (step S4). The AFE circuit 16 acquires the detection signal Rx from each sensor electrode 42, generates sensing data, and transmits the sensing data to the control circuit 60. The noise determination circuit 62 of the control circuit 60 performs the noise determination process described above based on the sensing data transmitted from the AFE circuit 16 (step S5).

[0100] Furthermore, the coordinate calculation circuit 63 executes coordinate calculation processing (step S6) based on the difference between the baseline data acquired in the baseline setting processing (step S2) and the sensing data.

[0101] Although FIG. 11 shows an example in which the coordinate calculation process (step S6) is executed after the noise determination process (step S5), the noise determination process (step S5) may be executed after the coordinate calculation process (step S6), or the noise determination process (step S5) and the coordinate calculation process (step S6) may be executed in parallel.

[0102] Next, the control circuit 60 determines whether or not the above-described conditions for performing frequency hopping (hereinafter also simply referred to as "frequency hopping conditions") are met (step S7).

[0103] If the frequency hopping condition is not met (step S7; No), the process proceeds to step S10.

[0104] If the frequency hopping condition is met (step S7; Yes), the control circuit 60 sets the electrical resistance of the DP circuit 22 to a value corresponding to the frequency of the rectangular wave signal Tx after frequency hopping (step S8).The control circuit 60 also sets the fundamental frequency of the rectangular wave signal Tx output from the AFE circuit 16 to the drive frequency after frequency hopping (step S9).

[0105] In addition, in Figure 11, an example is shown in which the drive frequency is set after the electrical resistance value of the DP circuit 22 is set, but it is also possible to have a configuration in which the electrical resistance value of the DP circuit 22 is set after the drive frequency is set, or a configuration in which the setting of the electrical resistance value of the DP circuit 22 and the setting of the drive frequency are performed in parallel.

[0106] When setting the electrical resistance value of the DP circuit 22 in step S8, the control circuit 60 references, for example, the DP control reference data described above to set the electrical resistance value of the DP circuit 22 corresponding to the frequency of the rectangular wave signal Tx after frequency hopping. This controls the electrical resistance value of the DP circuit 22 to an electrical resistance value corresponding to the rectangular wave signal Tx after frequency hopping. More specifically, when the detection mode is the hover detection mode, the control circuit 60 sets the electrical resistance value of the DP circuit 22 so that, for example, the amplitude value Vpp of the drive signal is 6.8 V. When the detection mode is the touch detection mode, the control circuit 60 sets the electrical resistance value of the DP circuit 22 so that, for example, the amplitude value Vpp of the drive signal is 2.5 V.

[0107] When the sensing operation of the detection device 1 is completed (Step S10; Yes), the detection device 1 ends the sensing operation. Examples of cases in which the sensing operation ends include when the power supply to the detection device 1 is stopped, or when a command to end the sensing operation is output from the processing device 110 to the detection device 1. When the sensing operation of the detection device 1 is not completed (Step S10; No), the operations from Step S3 onwards are repeatedly executed.

[0108] In the configuration of the above-described first embodiment, the control circuit 60 controls the amplitude value Vpp of the drive signal supplied from the drive signal generation circuit 20 to the peripheral electrode 41 and the shield electrode 44 in accordance with the sensing data output from the AFE circuit 16.

[0109] More specifically, in the detection mode setting process (step S3), when the current detection mode is the hover detection mode (first detection mode), the control circuit 60 maintains the hover detection mode (first detection mode) if the maximum value RDHmax of the sensing data RDH(n) of the multiple sensor electrodes 42 is less than a predetermined threshold value RDHth, and transitions to the touch detection mode (second detection mode) if the maximum value RDHmax is equal to or greater than the threshold value RDHth.

[0110] Furthermore, when the current detection mode is the touch detection mode (second detection mode), the control circuit 60 maintains the touch detection mode (second detection mode) if the maximum value RDTmax of the sensing data RDT(n) of the multiple sensor electrodes 42 is equal to or greater than a predetermined threshold value RDTth, and transitions to the hover detection mode (first detection mode) if the maximum value RDTmax is less than the threshold value RDTth.

[0111] Then, the control circuit 60 sets the electrical resistance value of the DP circuit 22 so that the amplitude value Vpp of the drive signal becomes a value according to the detection mode set in the detection mode setting process (step S3).

[0112] More specifically, when the detection mode set in the detection mode setting process (step S3) is the hover detection mode (first detection mode), the control circuit 60 controls the electrical resistance value of the DP circuit 22 so that the amplitude value Vpp of the drive signal becomes the first amplitude value (e.g., 6.8 V).

[0113] In addition, when the detection mode set in the detection mode setting process (step S3) is the touch detection mode (second detection mode), the control circuit 60 controls the electrical resistance value of the DP circuit 22 so that the amplitude value Vpp of the drive signal becomes a second amplitude value (e.g., 2.5 V) smaller than the first amplitude value.

[0114] In this way, in the hover detection mode (first detection mode), the amplitude value Vpp of the drive signal is controlled to be relatively large, and in the touch detection mode (second detection mode), the amplitude value Vpp of the drive signal is controlled to be relatively small. This makes it possible to suppress saturation of sensing data at the contact position when the object to be detected comes into contact with the detection surface of the sensor main body 40, and to suppress a decrease in position determination accuracy due to sensing data errors caused by capacitive coupling between adjacent sensor electrodes.

[0115] In addition, in a configuration in which a sine wave signal is generated by filtering the square wave signal Tx output from the AFE circuit 16 and the sine wave signal is amplified to generate a drive signal, a DP circuit 22 is connected in series to the input path of the amplifier circuit 24. In addition, the control circuit 60 is capable of setting the fundamental frequency of the square wave signal Tx, and the higher the fundamental frequency of the square wave signal Tx, the smaller the electrical resistance value of the DP circuit 22 becomes, and the lower the fundamental frequency of the square wave signal Tx, the larger the electrical resistance value of the DP circuit 22 becomes.

[0116] This allows the amplitude value Vpp of the drive signal to be kept constant (for example, 6.8 V in hover detection mode and 2.5 V in touch detection mode) even if, for example, the frequency hopping condition is met by the noise determination process and the fundamental frequency of the rectangular wave signal Tx (the frequency of the drive signal) is changed.

[0117] FIG. 14 is a plan view illustrating an example of a conductive layer in a detection region of the detection device according to embodiment 1. FIG. 15 is a plan view illustrating the position of the conductive layer in the detection device according to embodiment 1 in FIG. 14. FIG. 16 is a plan view illustrating another example of a conductive layer in a detection region of the detection device according to embodiment 1. FIG. 17 is a plan view illustrating the conductive layer of the detection device according to embodiment 1 in FIG. 16. FIG. 18 is a schematic diagram illustrating the flow of an electric field in an electric field generated in the conductive layer in FIGS. 15 and 17. FIG. 19 is an explanatory diagram illustrating the relationship between the ratio of the area of ​​a portion of the conductive layer overlapping the sensor electrode to the area of ​​the sensor electrode and the SNR, comparing conductive layers having square conductive layers with different areas. FIG. 20 is an explanatory diagram illustrating the relationship between the ratio of the area of ​​a portion of the conductive layer overlapping the sensor electrode to the area of ​​the sensor electrode and the SNR, comparing conductive layers having the same conductive layer length but different conductive layer widths.

[0118] 14, the diameter of the lead-out wiring L1 is narrower than the width of the conductive layer 471. The diameter of the lead-out wiring L1 is 0.00125 to 0.075 times the width of the conductive layer 471. For example, the diameter of the lead-out wiring L1 is 0.025 mmφ to 1.5 mmφ.

[0119] The detection circuit has a first side and a second side that intersects with the first side. The lead-out wiring L1 is led out from the first side so as to overlap between the sensor electrodes 42.

[0120] 15 , of the plurality of sensor electrodes 42, the sensor electrodes 42 that overlap with the conductive layer 471 are high-parasitic capacitance sensor electrodes 423 and 424, and the sensor electrodes 42 adjacent to the high-parasitic capacitance sensor electrodes 423 and 424 are high-sensitivity sensor electrodes 421 and 422 that detect the main electric field E (see FIG. 18 ). In this embodiment, the detected object 101 is disposed at a position that overlaps with the high-sensitivity sensor electrode 421.

[0121] The high-sensitivity sensor electrodes 421 and 422 are sensor electrodes with high detection sensitivity among the plurality of sensor electrodes 42 .

[0122] The high parasitic capacitance sensor electrodes 423 and 424 are sensor electrodes with large parasitic capacitance among the plurality of sensor electrodes 42 .

[0123] In this embodiment, the object to be detected 101 is, for example, a cubic member with each side measuring 30 mm.

[0124] Table 1 shows the measurement results of the detection sensitivity of the high-sensitivity sensor electrode 421 superimposed on the conductive layer 47 according to the first embodiment, and compares conductive layers 47 having square shapes and different areas. The area of ​​the conductive layer 47 is 100 mm ２ , 225 mm ２ , 400 mm ２ , 625 mm ２ The area of ​​the conductive layer 47 is 9.77% or more and 61.04% or less of the area of ​​the sensor electrode 42, and more preferably 39.06±1%. The area of ​​the portion of the conductive layer 47 overlapping with the high parasitic capacitance sensor electrode 423 or the high parasitic capacitance sensor electrode 424 is 4.1% or more and 28.7% or less of the area of ​​the sensor electrode 42, and more preferably 18.07±1%.

[0125]

[0126] 15, the conductive layer 471 is disposed between the high parasitic capacitance sensor electrodes 423 and 424 adjacent to each other in the first direction Dx. The length of each side of the conductive layer 471 is 20 mm, and the area of ​​the conductive layer 471 is 400 mm. ２ is.

[0127] The object to be detected 101 is disposed close to the high parasitic capacitance sensor electrode 423 and at a position overlapping with the high sensitivity sensor electrode 421 on the side from which the lead-out wiring L1 is not drawn out. The object to be detected 101 may also be disposed at a position overlapping with the high sensitivity sensor electrode 422.

[0128] The area of ​​the conductive layer 471 is 39.06±1% of the area of ​​the sensor electrode 42. The area of ​​the portion of the conductive layer 471 that overlaps with the high parasitic capacitance sensor electrode 423 or the high parasitic capacitance sensor electrode 424 is 18.07±1% of the area of ​​the sensor electrode.

[0129] As shown in Figures 3 and 18, when the object to be detected 101 is positioned so as to overlap with the high-sensitivity sensor electrode 421, an electric field E is generated by the high-sensitivity sensor electrode 421 in a direction diagonal to the third direction Dz toward the conductive layer 47, and the electric field E passing through the object to be detected 101 is concentrated, thereby increasing the parasitic capacitance of the high-sensitivity sensor electrode 421.

[0130] Furthermore, although wood, which is the material of the detection object 101, is difficult to detect, the detection sensitivity of the detection object 101 can be improved by arranging the wood in a position overlapping with the high-sensitivity sensor electrode 421. Note that even if the material of the detection object 101 is stone or glass, the detection sensitivity of the detection object 101 can be improved.

[0131] Here, in a detection device without the conductive layer 471, when the detectable object 101 is placed on the mark MA with the grain of the detectable object 101 oriented in the first direction Dx, the SNR (Signal to Noise Ratio) is 140. When the detectable object 101 is placed on the mark MA with the grain of the detectable object 101 oriented in the second direction Dy, the SNR is 140. When the detectable object 101 is placed on the mark MA with the grain of the detectable object 101 oriented in the third direction Dz, the SNR is 218. Hereinafter, the SNR of a detection device without the conductive layer 471 is taken as the reference value.

[0132] 19 , when the conductive layer 47 is square and the ratio of the area of ​​the portion of the conductive layer 47 overlapping with the high parasitic capacitance sensor electrode 423 or the high parasitic capacitance sensor electrode 424 to the area of ​​the sensor electrode 42 is 9.77% or more and 61.04% or less for the conductive layers 47 with different areas, the signal value becomes larger than the noise detected by the high-sensitivity sensor electrode 421, and the SNR becomes 140 or more, thereby improving the detection sensitivity of the object to be detected 101. In particular, when the ratio is 18.07±1%, the SNR is further improved.

[0133] 16, the diameter of the lead-out wiring L2 is narrower than the width of the conductive layer 472. The diameter of the lead-out wiring L2 is 0.00188 to 0.018 times the width of the conductive layer 472. For example, the diameter of the lead-out wiring L2 is 0.025 mmφ to 0.24 mmφ.

[0134] 16 , the lead-out wiring L2 is led out in a first direction Dx from the peripheral region BE toward the conductive layer 472, overlapping between the sensor electrodes 42, and the conductive layer 472 overlaps both of the adjacent sensor electrodes 42 in a second direction Dy that is orthogonal to the first direction Dx. The conductive layer 472 is connected to the lead-out wiring L2 that extends in the first direction Dx across the multiple sensor electrodes 42.

[0135] Table 2 shows the measurement results of the detection sensitivity of the high-sensitivity sensor electrode 422 superimposed on the conductive layer 47 according to the first embodiment. ２ The table compares conductive layers 47 with different widths, each fixed at 150 mm. ２ , 400 mm ２ , 600 mm ２ The area of ​​the conductive layer 47 is 14.65% to 58.59% of the area of ​​the sensor electrode 42, and more preferably 39.06±1%. The area of ​​the portion of the conductive layer 47 overlapping with the high parasitic capacitance sensor electrode 423 or the high parasitic capacitance sensor electrode 424 is 5.13% to 27.1% of the area of ​​the sensor electrode 42, and more preferably 17.33±1%.

[0136]

[0137] 17, the conductive layer 472 is disposed between the high parasitic capacitance sensor electrodes 423 and 424 adjacent to each other in the second direction. The high sensitivity sensor electrodes 421, 422, 425, and 426 are disposed in the vicinity of the high parasitic capacitance sensor electrodes 423 and 424. The length of one side of the conductive layer 472 is 30 mm, and the size of the other side of the conductive layer 472 is 13.33 mm. The area of ​​the conductive layer 472 is 400 mm ２ is.

[0138] The object to be detected 101 is placed at a position overlapping with the high-sensitivity sensor electrode 421. Note that the object to be detected 101 may also be placed at a position overlapping with any one of the high-sensitivity sensor electrodes 422, 425, and 426 that are close to the high-parasitic capacitance sensor electrodes 423 and 424.

[0139] In addition, the area of ​​the conductive layer 472 is 39.06±1% of the area of ​​the sensor electrode 42, and the area of ​​the portion of the conductive layer 472 that overlaps with the high parasitic capacitance sensor electrode 423 or the high parasitic capacitance sensor electrode 424 is 17.33±1% of the area of ​​the sensor electrode 42.

[0140] 20 , when conductive layers 47 have the same length but different widths, and the ratio of the area of ​​the portion of conductive layer 47 overlapping with high parasitic capacitance sensor electrode 423 or high parasitic capacitance sensor electrode 424 to the area of ​​sensor electrode 42 is 14.65% or more and 58.59% or less, the signal value becomes larger than the noise detected by high-sensitivity sensor electrode 421, and the SNR becomes 140 or more, thereby improving the detection sensitivity of the object to be detected 101. In particular, when the ratio is 17.33±1%, the SNR is further improved.

[0141] Furthermore, although wood, which is the material of the detection object 101, is difficult to detect, the detection sensitivity of the detection object 101 can be improved by arranging the wood in a position overlapping with the high-sensitivity sensor electrode 421. Note that even if the material of the detection object 101 is stone or glass, the detection sensitivity of the detection object 101 can be improved.

[0142] (Embodiment 2) Fig. 21 is a plan view showing a schematic configuration of a detection device according to embodiment 2. Fig. 22 is a schematic cross-sectional view showing an example of a schematic configuration of a detection device according to embodiment 2. Fig. 23 is a plan view illustrating a detection region of the detection device according to embodiment 2. Fig. 24 is a plan view illustrating a conductive layer of the detection device according to embodiment 2. Fig. 25 is a schematic diagram showing the flow of electricity in an electric field generated in the conductive layer according to embodiment 2. Fig. 26 is an explanatory diagram showing the relationship between the ratio of the area of ​​a portion of the conductive layer overlapping the sensor electrode to the area of ​​the sensor electrode and the SNR in the detection device according to embodiment 2. Note that in the following description, the same components as those in embodiment 1 are denoted by the same reference numerals, and redundant description will be omitted.

[0143] 21 , in the detection device 1A according to the second embodiment, the conductive layer 473 is connected to the lead-out wiring L1 extending from the first side 210 side of the detection circuit 2. The conductive layer 473 is disposed in a position close to the mark MA.

[0144] As shown in FIG. 22, the conductive layer 473 is disposed between the first cover member 271 and the second cover member 272 in a cross-sectional view.

[0145] As shown in FIG. 23, a conductive layer 473 is provided in the detection area SA at a position close to the detection target 101 .

[0146] 24, the detectable object 101 is disposed at a position overlapping the high-sensitivity sensor electrode 427. The conductive layer 473 overlaps the high-parasitic capacitance sensor electrode 428 adjacent to the high-sensitivity sensor electrode 427 in the second direction Dy.

[0147] Table 3 shows the measurement results of the detection sensitivity of the high-sensitivity sensor electrode 427 superimposed on the conductive layer 473 according to embodiment 2. Table 3 shows the measurement results when the object to be detected 101 is placed on the mark MA with the grain direction of the object to be detected 101 oriented in the first direction Dx.

[0148]

[0149] 24 , the conductive layer 473 is disposed so that the center of gravity of the conductive layer 473 overlaps the center of gravity of the high parasitic capacitance sensor electrode 428. The length of the conductive layer 473 is, for example, 7.5 mm. The width of the conductive layer 473 is 1.0 mm or more and 5.0 mm or less.

[0150] 23 and 24, the conductive layer 473 is arranged across multiple sensor electrodes 42 along the first direction Dx, and the area of ​​the portion of the conductive layer 473 that overlaps with the high parasitic capacitance sensor electrode 428 is 3.13% or more and 15.63% or less of the area of ​​the high parasitic capacitance sensor electrode 428.

[0151] As shown in Figure 25, an electric field E caused by the sensor electrode 42 that is close to the conductive layer 473 and overlaps with the object to be detected 101 is generated diagonally toward the conductive layer 473 with respect to the third direction Dz, and the parasitic capacitance of the high-sensitivity sensor electrode 421 where the electric field E passing through the object to be detected 101 is concentrated increases.

[0152] As shown in Table 3 and Figure 26, when the ratio of the area of ​​the portion of the conductive layer 473 overlapping with the high parasitic capacitance sensor electrode 428 to the area of ​​the sensor electrode 42 is 3.13% or more and 15.63% or less, that is, when the width of the conductive layer 473 is 1 mm or more and 5 mm or less, the signal value becomes larger than the noise detected by the high-sensitivity sensor electrode 421, so the SNR becomes 140 or more, and the detection sensitivity of the object to be detected 101 can be improved.

[0153] (Modification of Embodiment 2) Fig. 27 is a plan view illustrating a detection region of a detection device according to a modification of Embodiment 2. Fig. 28 is a plan view illustrating a conductive layer of a detection device according to a modification of Embodiment 2. Fig. 29 is an explanatory diagram showing the relationship between the ratio of the area of ​​a portion of the conductive layer overlapping the sensor electrode to the area of ​​the sensor electrode and the SNR in a detection device according to a modification of Embodiment 2. Note that in the following description, the same components as in Embodiment 1 are denoted by the same reference numerals, and redundant description will be omitted.

[0154] 27 , a conductive layer 473a is provided in the detection area SA of the detection device 1Aa according to the modified example of the second embodiment, at a position close to the detection target 101. The conductive layer 473a is arranged across the plurality of sensor electrodes 42 along the first direction Dx. The conductive layer 473a is connected to the lead-out wiring L1 extending from the first side 210 of the detection circuit 2.

[0155] 28 , the detectable object 101 is disposed at a position overlapping the high-sensitivity sensor electrode 427. The conductive layer 473a overlaps the high-parasitic capacitance sensor electrode 428 adjacent to the high-sensitivity sensor electrode 427 in the second direction Dy.

[0156] As shown in Figure 28, the conductive layer 473a is positioned at a position shifted from the position of the center of gravity of the conductive layer 473 (see Figure 22) along the second direction Dy toward the object to be detected 101 by 1 / 4 of the length of one side of the sensor electrode 428.

[0157] Table 4 shows the measurement results of the detection sensitivity of the high-sensitivity sensor electrode 427 superimposed on the conductive layer 473a according to the modified example of Embodiment 2. Table 4 shows the measurement results when the object to be detected 101 is placed on the mark MA with the grain direction of the object to be detected 101 oriented in the first direction Dx.

[0158]

[0159] 29 , when the ratio of the area of ​​the portion of the conductive layer 473a overlapping with the high parasitic capacitance sensor electrode 428 to the area of ​​the sensor electrode 42 is 3.13% or more and 7.81% or less, i.e., when the width of the conductive layer 473 is 1 mm or more and 2.5 mm or less, the signal value detected by the high-sensitivity sensor electrode 421 is larger than the noise, and the SNR is 140 or more, thereby improving the detection sensitivity of the object to be detected 101. Note that when the ratio of the area of ​​the portion of the conductive layer 473a overlapping with the high parasitic capacitance sensor electrode 428 to the area of ​​the sensor electrode 42 is 15.63%, i.e., when the width of the conductive layer 473 is 5 mm or more, the SNR is 140 or less, and the detection device 1Aa according to the modification of Embodiment 2 has a narrower optimal range for the ratio of the area of ​​the portion of the conductive layer 473a overlapping with the high parasitic capacitance sensor electrode 428 to the area of ​​the sensor electrode 42, compared to the detection device 1A according to Embodiment 2.

[0160] (Embodiment 3) Fig. 30 is a plan view showing a schematic configuration of a detection device according to embodiment 3. Fig. 31 is a schematic cross-sectional view showing an example of a schematic configuration of a detection device according to embodiment 3. Fig. 32 is a plan view for explaining a conductive layer of a detection device according to embodiment 3. Fig. 33 is a schematic view showing the flow of an electric field in an electric field generated in a conductive layer according to embodiment 3. Fig. 34 is an explanatory diagram showing the relationship between the ratio of the area of ​​the conductive layer overlapping the sensor electrode to the area of ​​the sensor electrode and the SNR in a detection device according to embodiment 3. Fig. 35 is a schematic cross-sectional view showing another example of the position of the conductive layer. In the following description, the same components as those in embodiment 1 are denoted by the same reference numerals, and redundant description will be omitted.

[0161] 30 , in the detection device 1B according to the third embodiment, the conductive layer 474 is connected to the lead-out wiring L1 extending from the first side 210 side of the detection circuit 2. The conductive layer 474 is disposed in a position close to the mark MA.

[0162] As shown in FIG. 31, the conductive layer 474 is disposed between the first cover member 271 and the second cover member 272 in a cross-sectional view.

[0163] Table 5 shows the measurement results of the detection sensitivity of the high-sensitivity sensor electrode 427 superimposed on the conductive layer 474 according to embodiment 3. Table 5 shows the measurement results when the grain direction of the detection object 101 placed on the mark MA is the first direction Dx.

[0164]

[0165] 32 , the conductive layer 474 overlaps at least one sensor electrode 42, and is disposed in a position where the entire conductive layer 474 overlaps the sensor electrode 42. The length of the conductive layer 474 is equal to the length of one side of the sensor electrode 42, e.g., 32 mm. The width of the conductive layer 474 is 2.5 mm or more and 10 mm or less.

[0166] As shown in FIG. 32, the size of the conductive layer overlapping the sensor electrode is 7.81% or more and 31.25% or less of the size of the sensor electrode.

[0167] As shown in Figure 33, an electric field E caused by the sensor electrode 42 that is close to the conductive layer 474 and overlaps with the object to be detected 101 is generated diagonally toward the conductive layer 474 with respect to the third direction Dz, and the electric field E passing through the object to be detected 101 is concentrated, increasing the parasitic capacitance of the high-sensitivity sensor electrode 421 where the electric field E passing through the object to be detected 101 is concentrated.

[0168] As shown in Table 5 and Figure 34, when the ratio of the area of ​​the conductive layer 474 overlapping with the high parasitic capacitance sensor electrode 428 to the area of ​​the sensor electrode 42 is 7.81% or more and 31.25% or less, that is, when the width of the conductive layer 473 is 2.5 mm or more and 10 mm or less, the signal value becomes larger than the noise detected by the high-sensitivity sensor electrode 421, so the SNR becomes 140 or more, and the detection sensitivity of the object to be detected 101 can be improved.

[0169] Table 6 shows the measurement results of the detection sensitivity of the high-sensitivity sensor electrode 427 superimposed on the conductive layer 474. Table 6 shows the measurement results when the grain directions of the detection object 101 placed on the mark MA are different and the ratio of the area of ​​the conductive layer 474 superimposed on the high parasitic capacitance sensor electrode 428 to the area of ​​the sensor electrode 42 is 23.44%. The grain directions of the detection object 101 placed on the mark MA are the first direction Dx, the second direction Dy, and the third direction Dz.

[0170]

[0171] In Table 6, when the grain of the object 101 placed on the mark MA is oriented in the first direction Dx or the second direction Dy, the electric field E is generated in a concentrated manner in the third direction Dz, resulting in an SNR of 140 or more and improved detection sensitivity. However, when the grain of the object 101 placed on the mark MA is oriented in the third direction Dz, the SNR is 218 or less and detection sensitivity does not improve.

[0172] 35 , the conductive layer 474a is disposed on the surface of the cover member 270. In a plan view, the conductive layer 474a is disposed at the same position as the conductive layer 474. The length of the conductive layer 474a is the same as the length of the conductive layer 474.

[0173] Table 7 shows the measurement results of the detection sensitivity of the high-sensitivity sensor electrode 427 overlapping the conductive layers 474, 474a. Table 7 shows the measurement results when the grain direction of the detection object 101 placed on the mark MA is the first direction Dx, and the ratio of the area of ​​the conductive layer 474 or the conductive layer 474a overlapping with the high parasitic capacitance sensor electrode 428 to the area of ​​the sensor electrode 42 is 23.44%.

[0174]

[0175] In Table 7, the conductive layer 474a has a shorter distance to the object 101 than the conductive layer 474, and therefore has a smaller parasitic capacitance. The high-sensitivity sensor electrode 421 on the conductive layer 474a detects a higher signal value and lower noise. As a result, the SNR can be increased, and the detection sensitivity can be improved.

[0176] Although preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to such embodiments. The contents disclosed in the embodiments are merely examples, and various modifications are possible within the scope of the present disclosure. Appropriate modifications made within the scope of the present disclosure also naturally fall within the technical scope of the present disclosure.

[0177] 1, 1A, 1Aa, 1B Detector 2 Detector circuit 40 Sensor body 41 Peripheral electrode 42 Sensor electrode 421, 422, 425, 426, 427 High-sensitivity sensor electrodes 423, 424, 428 High-parasitic capacitance sensor electrodes 47, 471, 472, 473, 474, 474a Conductive layer 101 Object to be detected 210 First side 220 Second side 270 Cover member 271 First cover member 272 Second cover member BE Peripheral area L1 Lead-out wiring MA Mark SA Detection area

Claims

1. A detection device comprising: a detection area for detecting electrostatic capacitance; a plurality of sensor electrodes arranged in a matrix in the detection area; and at least one planar conductive layer to which a predetermined reference potential is supplied; wherein, of the plurality of sensor electrodes, a sensor electrode that overlaps with the conductive layer is a high-parasitic capacitance sensor electrode; and a sensor electrode of the sensor electrodes adjacent to the high-parasitic capacitance sensor electrode is a high-sensitivity sensor electrode that detects a main electric field.

2. The detection device according to claim 1, wherein the conductive layer overlaps at least one sensor electrode, and a portion of the conductive layer overlaps a portion of the sensor electrode but does not overlap another portion of the sensor electrode.

3. The detection device according to claim 2, wherein the conductive layer is disposed between the sensor electrodes, and the area of ​​the portion of the conductive layer overlapping the sensor electrodes is 9.8% or more and 61% or less of the area of ​​the sensor electrodes.

4. The detection device according to claim 2, wherein the conductive layer is disposed across a plurality of the sensor electrodes, and the area of ​​the portion of the conductive layer overlapping the sensor electrodes is 3.13% or more and 15.63% or less of the area of ​​the sensor electrodes.

5. The detection device according to claim 1, wherein the conductive layer overlaps at least one sensor electrode, the entire conductive layer overlaps the sensor electrode, the length of the conductive layer is equal to the length of one side of the sensor electrode, and the area of ​​the conductive layer overlapping the sensor electrode is 7.81% or more and 31.25% or less of the area of ​​the sensor electrode.

6. A detection device according to claim 2 or 5, wherein a dielectric cover member is disposed on the sensor electrode, the cover member having a first cover member and a second cover member, and the conductive layer is disposed between the first cover member and the second cover member.

7. The detection device according to claim 6, wherein the surface of the first cover member is exposed, and marks corresponding to each of the sensor electrodes are provided on the surface of the first cover member.

8. A detection device as described in claim 7, comprising: a lead-out wiring that supplies a predetermined reference potential to the conductive layer; and a detection circuit that drives each of the sensor electrodes and detects capacitance, wherein the detection circuit has a first side and a second side that intersects with the first side, the diameter of the lead-out wiring is narrower than the width of the conductive layer, and the lead-out wiring is led out from the first side to overlap between each of the sensor electrodes.

9. A detection device as described in claim 8, further comprising: lead-out wiring for supplying a reference potential to the conductive layer; the lead-out wiring is led out in a first direction from a peripheral region surrounding the detection region toward the conductive layer, overlapping between each of the sensor electrodes; and the conductive layer overlaps both of the adjacent sensor electrodes in a second direction perpendicular to the first direction.

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