Capacitive sensor, sensor sheet, sensor unit, detection circuit, and capacitance detection device

Abstract

A capacitive sensor according to this invention is provided with: a base material (101); a detection electrode (102) disposed on one surface (101A) of the base material (101); a first side shield electrode (103) provided in parallel with the detection electrode (102) on the one surface (101A) of the base material (101); and a back shield electrode (106) disposed to face the detection electrode (102) via the base material (101) on the other surface (101B) of the base material (101), wherein a first AC drive voltage is applied to the detection electrode (102), a second AC drive voltage having the same frequency and phase as the first AC drive voltage is applied to the first side shield electrode (103) and the back shield electrode (106), and a side ground electrode (104) connected to the ground potential is further provided in parallel with the detection electrode (102) and the first side shield electrode (103) on the one surface (101A) of the base material (101).

Description

Capacitive sensor, sensor sheet, sensor unit, detection circuit, and capacitance detection device

[0001] The present invention relates to a capacitance sensor, a sensor sheet, a sensor unit, a detection circuit, and a capacitance detection device.

[0002] The following Patent Document 1 discloses a technology for applying a potential equivalent to that of the sensor electrode to the auxiliary electrode and the shield electrode in a capacitive proximity sensor having a sensor electrode, an auxiliary electrode arranged near the sensor electrode, and a shield electrode arranged on the back side of the sensor electrode.

[0003] Furthermore, Patent Documents 2 and 3 listed below disclose a technique for adjusting a second AC voltage in a capacitance detection device having a shield electrode arranged on the back side of the detection electrode so that the drive current of the detection electrode becomes zero when there is no object close to the detection electrode.

[0004] Furthermore, Patent Document 3 listed below discloses a technique for adjusting a second AC voltage in a capacitance detection device having a shield electrode arranged on the back side of the detection electrode, so that the amplitude of an operational amplifier is smaller than the amplitude of a first AC voltage supplied to the shield electrode.

[0005] International Publication No. 2009 / 044920 International Publication No. 2018 / 116706 International Publication No. 2021 / 090636

[0006] However, in the techniques of Patent Documents 1 to 3, if the conductivity or dielectric constant of the object to be detected is low, the capacitance of the object to be detected by the detection electrode becomes small, and therefore the object to be detected cannot be detected with high sensitivity.

[0007] A capacitance-type sensor according to one embodiment comprises a substrate, a detection electrode arranged on one surface of the substrate, a first side shield electrode arranged in parallel with the detection electrode on the one surface of the substrate, and a back shield electrode arranged opposite the detection electrode via the substrate on the other surface of the substrate, wherein a first AC drive voltage is applied to the detection electrode, and a second AC drive voltage having the same frequency and phase as the first AC drive voltage is applied to the first side shield electrode and the back shield electrode, and the capacitance-type sensor further comprises a side ground electrode arranged in parallel with the detection electrode and first side shield electrode on the one surface of the substrate and connected to a ground potential.

[0008] According to the capacitance type sensor of one embodiment, it is possible to detect a detection target having a low conductivity or dielectric constant with high sensitivity.

[0009]

[0010] An embodiment will be described below with reference to the drawings. For convenience, in the following description, the X-axis direction will be referred to as the left-right direction, the Y-axis direction as the front-rear direction, and the Z-axis direction as the up-down direction. However, the positive X-axis direction will be referred to as the rightward direction, the positive Y-axis direction as the forward direction, and the positive Z-axis direction as the upward direction. These directions indicate relative positional relationships within the device and do not limit the installation direction or operation direction of the device. Any devices that have the same relative positional relationships within the device, even if they have different installation directions or operation directions, are all within the scope of the present invention.

[0011] First Embodiment (Overview of Capacitance Detection Device 10) Fig. 1 is a plan view of a capacitance detection device 10 according to a first embodiment. As shown in Fig. 1, the capacitance detection device 10 includes a sensor sheet 12. The sensor sheet 12 has a plurality of capacitance sensors 100 (three capacitance sensors 100 in the example shown in Fig. 1) arranged side by side in the left-right direction (X-axis direction).

[0012] Each capacitance sensor 100 provided on the sensor sheet 12 is a sheet-like sensor that extends linearly in the front-to-rear direction (Y-axis direction). Each capacitance sensor 100 provided on the sensor sheet 12 is configured to be able to detect a detection target 20 placed on the capacitance sensor 100 by a self-capacitance method. The sensor sheet 12 is entirely covered by a cover 107.

[0013] The capacitance detection device 10 also includes a circuit board 11 and a detection circuit 120 provided on the circuit board 11. The detection circuit 120 is connected to each of the multiple capacitance sensors 100 provided on the sensor sheet 12 via lead wiring 11A. Each of the multiple capacitance sensors 100 provided on the sensor sheet 12 has a connection portion 100A with the lead wiring 11A provided at an end on the positive side of the Y axis (one end in the first direction). The detection circuit 120 drives each of the multiple capacitance sensors 100 provided on the sensor sheet 12, thereby enabling each of the multiple capacitance sensors 100 provided on the sensor sheet 12 to detect the detection target 20 and enabling the detection result of the detection target 20 to be obtained from each of the multiple capacitance sensors 100 provided on the sensor sheet 12.

[0014] For example, the capacitance detection device 10 can be used to detect the display state of products on a shelf 21 of a product shelf in a store that sells multiple products. For example, in the example shown in Fig. 1 , the sensor sheet 12 included in the capacitance detection device 10 includes a capacitance sensor 100 for each of multiple product rows 21A (three product rows 21A in the example shown in Fig. 1 ) on the shelf 21 of the product shelf. This allows the capacitance detection device 10 to detect the display state of products in each of the multiple product rows 21A (presence or absence of products, number of products, etc.) using the self-capacitance method, using the multiple capacitance sensors 100 included in the sensor sheet 12.

[0015] (Configuration of Capacitive Sensor 100) Fig. 2 is an exploded plan view of the capacitive sensor 100 according to the first embodiment. Fig. 3 is a cross-sectional view of the capacitive sensor 100 according to the first embodiment.

[0016] As shown in Figures 2 and 3, the capacitance sensor 100 according to the first embodiment includes a substrate 101, a detection electrode 102, a first side shield electrode 103, a side ground electrode 104, a back shield electrode 106, and a cover 107.

[0017] The substrate 101 is a plate-shaped member made of an insulating material and supports each electrode (the detection electrode 102, the first side shield electrode 103, the side ground electrode 104, and the back shield electrode 106). When viewed from above (the positive direction of the Z axis), the substrate 101 has a rectangular shape with a constant width in the left-right direction (the X axis) and a constant length in the front-back direction (the Y axis). The substrate 101 is formed using, for example, an insulating resin such as PET (polyethylene terephthalate) or PMMA (polymethyl methacrylate), glass, glass epoxy resin, glass polyimide resin, paper epoxy resin, or paper phenolic resin. The substrate 101 may also be formed integrally with the circuit board 11.

[0018] The detection electrode 102 is a thin-film electrode provided on the upper surface 101A (an example of “one surface”) of the substrate 101 and made of a conductive material such as metal, inorganic conductive oxide, or conductive resin. The detection electrode 102 has two linear portions 102A extending linearly in the front-rear direction (Y-axis direction) and one connecting portion 102B extending linearly in the left-right direction (X-axis direction) and connecting the rear ends (negative side of the Y-axis) of the two linear portions 102A. As a result, the detection electrode 102 has a U-shape when viewed from above (positive direction of the Z-axis). A first side shield electrode 103 and a side ground electrode 104 are disposed between the two linear portions 102A of the detection electrode 102. That is, the two linear portions 102A of the detection electrode 102 are arranged in parallel with the two linear portions 103A of the first side shield electrode 103 and the side ground electrode 104. The detection electrode 102 is connected to the detection circuit 120. The detection electrode 102 is driven by application of a first AC drive voltage V1 from the detection circuit 120.

[0019] The first side shield electrode 103 is a thin-film electrode provided on the upper surface 101A of the substrate 101 and made of a conductive material such as metal, inorganic conductive oxide, or conductive resin. The first side shield electrode 103 has two linear portions 103A extending linearly in the front-rear direction (Y-axis direction) and one connecting portion 103B extending linearly in the left-right direction (X-axis direction) and connecting the rear ends (negative side of the Y-axis) of the two linear portions 103A. As a result, the first side shield electrode 103 has a U-shape when viewed from above (positive direction of the Z-axis). The first side shield electrode 103 is provided between (i.e., inside) the two linear portions 102A of the detection electrode 102 in the width direction (X-axis direction) of the capacitive sensor 100. A side ground electrode 104 is also provided between the two linear portions 103A of the first side shield electrode 103. That is, the two straight line portions 103A of the first side shield electrode 103 are arranged in parallel with the two straight line portions 102A of the detection electrode 102 and the side ground electrode 104. The first side shield electrode 103 is electrically connected to the detection circuit 120. The first side shield electrode 103 is driven by application of a second AC drive voltage V2 from the detection circuit 120. The second AC drive voltage V2 has the same frequency and phase as the first AC drive voltage V1 applied to the detection electrode 102.

[0020] The side ground electrode 104 is a thin-film electrode provided on the upper surface 101A of the substrate 101 and made of a conductive material such as a metal, an inorganic conductive oxide, or a conductive resin. The side ground electrode 104 has a strip shape that extends linearly in the front-to-rear direction (Y-axis direction) on the upper surface 101A of the substrate 101. The side ground electrode 104 is connected to the ground potential of the circuit board 11, similar to the detection circuit 120. In the example shown in FIGS. 2 and 3 , the side ground electrode 104 is provided in the center of the capacitance-type sensor 100 in the width direction (X-axis direction), i.e., between the two linear portions 103A of the first side shield electrode 103. As a result, the side ground electrode 104 is juxtaposed to the two linear portions 103A of the first side shield electrode 103 and the two linear portions 102A of the detection electrode 102.

[0021] The back shield electrode 106 is a thin-film electrode provided on the lower surface 101B (an example of the "other surface") of the substrate 101 and made of a conductive material such as metal, inorganic conductive oxide, or conductive resin. The back shield electrode 106 has the same shape (i.e., rectangular) as the lower surface 101B of the substrate 101 when viewed from above (positive Z-axis direction) so as to cover the entire lower surface 101B. The back shield electrode 106 is disposed opposite the detection electrode 102 across the substrate 101. The back shield electrode 106 is electrically connected to the detection circuit 120. The back shield electrode 106 is driven by application of a second AC drive voltage V2 from the detection circuit 120. The back shield electrode 106 and the first side shield electrode 103 are also electrically connected. As a result, the second AC drive voltage V2 of the same frequency and phase is applied from the detection circuit 120 to both the back shield electrode 106 and the first side shield electrode 103.

[0022] The cover 107 is provided on the top surface and is an insulating member that covers the top surface 101A of the substrate 101 and each electrode (the detection electrode 102, the first side shield electrode 103, and the side ground electrode 104). The cover 107 has the same shape (i.e., rectangular) as the top surface 101A of the substrate 101 when viewed from above (positive direction of the Z axis) so as to cover the entire top surface 101A of the substrate 101. The cover 107 is formed in the shape of a film or a plate that is thicker than a film using a resin material such as PET (polyethylene terephthalate), PMMA (polymethyl methacrylate), or a photosensitive resist such as a novolac resin, or a glass material, for example.

[0023] (Parasitic Capacitance Generated in the Capacitive Sensor 100) FIG. 4 is a diagram showing parasitic capacitance generated in the capacitive sensor 100 according to the first embodiment. FIG. 4 is a schematic conceptual diagram illustrating the electrodes provided on one side in the width direction (the positive or negative side of the X axis) of the side ground electrode 104 provided in the center in the width direction (X axis direction) in FIGS. 2 and 3 . As shown in FIG. 4 , the following parasitic capacitances are generated in the capacitive sensor 100 according to the first embodiment. The first side shield electrode 103 is electrically connected to the back shield electrode 106. The side ground electrode 104 is connected to the ground potential of the circuit board 11, similar to the detection circuit 120.

[0024] Parasitic capacitance between the detection electrode 102 and the ground potential: Crgl(a) Parasitic capacitance between the detection electrode 102 and the side ground electrode 104: Crgl(b) Parasitic capacitance between the detection electrode 102 and the back shield electrode 106: Crs(a) Parasitic capacitance between the detection electrode 102 and the first side shield electrode 103: Crs(b) Parasitic capacitance between the side ground electrode 104 and the back shield electrode 106: Csg(a) Parasitic capacitance between the side ground electrode 104 and the first side shield electrode 103: Csg(b)

[0025] (Circuit Model of Capacitance Detection Device 10) Fig. 5 is a diagram showing a circuit model of the capacitance detection device 10 according to the first embodiment (when the detection target 20 is not present on the capacitance sensor 100). Fig. 6 is a diagram showing a circuit model of the capacitance detection device 10 according to the first embodiment (when the detection target 20 is present on the capacitance sensor 100).

[0026] As shown in FIGS. 5 and 6, the detection circuit 120 includes a capacitance detection unit 121, a processing unit 122, and an I / F (interface) 124.

[0027] The capacitance detection portion 121 is electrically connected to the detection electrode 102, the first side shield electrode 103, and the back shield electrode 106. The first side shield electrode 103 and the back shield electrode 106 are also electrically connected to each other.

[0028] The capacitance detection unit 121 has a first drive / detection circuit 121A and a second drive circuit 121B. The first drive / detection circuit 121A generates a first AC drive voltage V1 and applies the first AC drive voltage V1 to the detection electrode 102. The first drive / detection circuit 121A also detects a change Ie in a current Is flowing through the detection electrode 102 as a change in capacitance in the detection electrode 102 and outputs a detection signal Ds based on the change Ie in the current Is. The second drive circuit 121B generates a second AC drive voltage V2 having the same frequency and phase as the first AC drive voltage V1 and applies the second AC drive voltage V2 to the first side shield electrode 103 and the back shield electrode 106.

[0029] 7 is a diagram showing an example of the circuit configuration of the capacitance detection unit 121 included in the capacitance detection device 10 according to the first embodiment. For example, as shown in FIG. 7, the capacitance detection unit 121 includes a first drive / detection circuit 121A, a second drive circuit 121B, and an A / D converter 25.

[0030] The first drive / detection circuit 121A is electrically connected to the detection electrode 102 via the lead wiring 11A-1. The first drive / detection circuit 121A also has an operational amplifier 30, a feedback resistor 40, a feedback capacitor 50, and a first AC voltage circuit 60 which is a first AC power supply.

[0031] The first AC voltage circuit 60 generates a first AC drive voltage V 1 and applies the first AC drive voltage V 1 to the non-inverting input terminal (+) of the operational amplifier 30 .

[0032] The inverting input terminal (−) of the operational amplifier 30 is connected to the detection electrode 102 via the lead wire 11A-1, and the first AC voltage circuit 60 is connected to the non-inverting input terminal (+) of the operational amplifier 30. The operational amplifier 30 amplifies the voltage difference between the inverting input terminal (−) connected to the detection electrode 102 and the non-inverting input terminal (+) to which the first AC drive voltage V1 is applied, and outputs an output voltage Vo. A feedback resistor 40 and a feedback capacitor 50 are connected in parallel between the output terminal and the inverting input terminal (−) of the operational amplifier 30, providing negative feedback. The resistance value of the feedback resistor 40 is variable. The capacitance value of the feedback capacitor 50 is adjustable. The operational amplifier 30 outputs a change in the capacitance of the detection electrode 102 as an output voltage Vo based on a change Ie in the current Is flowing through the detection electrode 102. The output voltage Vo is converted into a detection signal Ds by an A / D converter 25.

[0033] The second drive circuit 121B has a second AC voltage circuit 70, which is a second AC power supply. The second AC voltage circuit 70 is electrically connected to the first side shield electrode 103 and the back shield electrode 106 via the lead wiring 11A-2. The second drive circuit 121B uses the second AC voltage circuit 70 to generate a second AC drive voltage V2 that has the same frequency and phase as the first AC drive voltage V1.

[0034] In the detection circuit 120 according to the first embodiment, the amplitude of the second AC drive voltage V2 output from the second drive circuit 121B is preferably greater than the amplitude of the first AC drive voltage V1 output from the first drive / detection circuit 121A. This allows the detection circuit 120 according to the first embodiment to effectively cancel the parasitic capacitance Crgl (Crgl(a)+Crgl(b)) between the detection electrode 102 and the ground potential and between the detection electrode 102 and the side ground electrode 104 by using the parasitic capacitance Crs (Crs(a)+Crs(b)) generated between the detection electrode 102 and the first side shield electrode 103 and the back shield electrode 106, thereby enabling the detection electrode 102 to obtain a detection signal with a high S / N ratio. Furthermore, saturation of the output voltage Vo of the operational amplifier 30 can be prevented, thereby increasing the dynamic range of the output voltage Vo.

[0035] The processing unit 122 executes various predetermined processes based on the detection signal Ds output from the capacitance detection unit 121. For example, the processing unit 122 executes predetermined processes such as determining whether or not a detection target 20 exists on the capacitance sensor 100, determining the number of detection targets 20 present on the capacitance sensor 100, etc., based on the detection signal Ds. For example, the processing unit 122 is configured with a processing processor (e.g., a CPU (Central Processing Unit)), memory (e.g., a RAM (Random Access Memory)), etc., and executes various predetermined processes by the processing processor executing a program stored in the memory. For example, an integrated circuit (IC) is used as the processing unit 122.

[0036] The I / F 124 outputs data indicating the results of a predetermined process performed by the processing unit 122 (e.g., the presence or absence of a detection target 20 on the capacitance sensor 100, the number of detection targets 20 present on the capacitance sensor 100, etc.) to another device that uses the data.

[0037] (Detection Operation of Capacitive Sensor 100) In the capacitive sensor 100 according to the first embodiment configured as described above, the detection electrode 102 is driven by a first AC drive voltage V1 supplied from the detection circuit 120. As a result, in the capacitive sensor 100 according to the first embodiment, when the placement state of the detection object 20 on the capacitive sensor 100 changes, the capacitance (Crg+Crg') of the detection object 20 detected by the detection electrode 102 changes. Therefore, the detection circuit 120 according to the first embodiment can determine the placement state of the detection object 20 on the capacitive sensor 100 (presence or absence of the detection object 20, the number of the detection objects 20, etc.) based on the capacitance (Crg+Crg') of the detection object 20 detected by the detection electrode 102.

[0038] Here, the capacitance sensor 100 according to the first embodiment has a first side shield electrode 103 arranged in parallel with the detection electrode 102 on the upper surface 101A of the substrate 101, and the first side shield electrode 103 is driven by a second AC drive voltage V2 having the same frequency and phase as a first AC drive voltage V1 applied to the detection electrode 102. The capacitance sensor 100 according to the first embodiment also has a back shield electrode 106 arranged on the lower surface 101B of the substrate 101 so as to face the detection electrode 102, and the back shield electrode 106 is driven by a second AC drive voltage V2 having the same frequency and phase as the first AC drive voltage V1 applied to the detection electrode 102. As a result, in the capacitance sensor 100 of the first embodiment, as shown in Figures 5 and 6, the sum of the current Irgl(b) flowing through the parasitic capacitance Crgl(b) between the detection electrode 102 and the side ground electrode 104 and the current Irgl(a) flowing through the parasitic capacitance Crgl(a) between the detection electrode 102 and the ground potential is offset by the sum of the current Irs-s flowing through the parasitic capacitance Crs(b) between the first side shield electrode 103 and the detection electrode 102 and the current Irs-b flowing through the parasitic capacitance Crs(a) between the back shield electrode 106 and the detection electrode 102. This is because the capacitance detection unit 121 (first drive / detection circuit 121A) adjusts the amplitude of the first AC drive voltage V1 applied to the detection electrode 102 to be smaller than the amplitude of the second AC voltage so that the sum of the currents Irs-b and Irs-s flowing into the detection electrode 102 from the back shield electrode 106 and the first side shield electrode 103 to which the second AC drive voltage V2 is applied is equal to the sum of the currents Irgl(a) and Irgl(b) flowing out of the detection electrode 102. Therefore, in the capacitance type sensor 100 of the first embodiment, the sum of the parasitic capacitance Crgl(b) between the detection electrode 102 and the side ground electrode 104 and the parasitic capacitance Crgl(a) between the detection electrode 102 and the ground potential can be offset by the sum of the parasitic capacitance Crs(b) between the first side shield electrode 103 and the detection electrode 102 and the parasitic capacitance Crs(a) between the back shield electrode 106 and the detection electrode 102.

[0039] As described above, in the capacitance sensor 100 according to the first embodiment, when no detection object 20 is present on the capacitance sensor 100 as shown in FIG. 5 , the parasitic capacitance Crgl (Crgl(a) + Crgl(b)) generated between the detection electrode 102 and the ground potential and between the detection electrode 102 and the side ground electrode 104 can be offset by the parasitic capacitance (Crs(a) + Crs(b)) of the first side shield electrode 103 and the back shield electrode 106. As shown in FIG. 6 , when a detection object 20 is present on the capacitance sensor 100, the capacitance detected by the detection electrode 102 is the capacitance (Crg + Crg') of the detection object 20, with the parasitic capacitance Crgl eliminated. This improves the detection accuracy of the detection electrode 102 for the detection object 20. The capacitance (Crg+Crg') of the detection object 20 detected by the detection electrode 102 is detected by the first drive and detection circuit 121A as a change Ie in the current Is.

[0040] 6 , when the detection object 20 is present, the capacitance type sensor 100 according to the first embodiment generates a capacitance Crg between the detection electrode 102 and the detection object 20, and generates a capacitance Crg′ between the detection object 20 and the side ground electrode 104. Therefore, when the detection object 20 is present, the capacitance type sensor 100 according to the first embodiment amplifies the capacitance of the detection object 20 detected by the detection electrode 102 to the sum of the capacitance Crg and the capacitance Crg′, thereby improving the detection accuracy of the detection object 20 by the detection electrode 102.

[0041] As described above, the capacitance-type sensor 100 according to the first embodiment includes a substrate 101, a detection electrode 102 arranged on one surface of the substrate 101, a first side shield electrode 103 arranged in parallel with the detection electrode 102 on one surface of the substrate 101, and a back shield electrode 106 arranged on the other surface of the substrate 101 so as to face the detection electrode 102 with the substrate 101 interposed therebetween. A first AC drive voltage V1 is applied to the detection electrode 102, and a second AC drive voltage V2 having the same frequency and phase as the first AC drive voltage V1 is applied to the first side shield electrode 103 and the back shield electrode 106. The capacitance-type sensor 100 further includes a side ground electrode 104 arranged in parallel with the detection electrode 102 and first side shield electrode 103 on one surface of the substrate 101 and connected to a ground potential.

[0042] As a result, even if the detection object 20 present on one surface of the substrate 101 has a low conductivity or dielectric constant, the capacitance-type sensor 100 according to the first embodiment can reduce each parasitic capacitance (parasitic capacitance between the detection electrode 102 and the back shield electrode 106, parasitic capacitance between the detection electrode 102 and the ground potential, parasitic capacitance between the detection electrode 102 and the first side shield electrode 103, and parasitic capacitance between the detection electrode 102 and the side ground electrode 104) by the first side shield electrode 103 and the back shield electrode 106. Furthermore, the capacitance-type sensor 100 according to the first embodiment can amplify the capacitance of the detection object 20 detected by the detection electrode 102 to the sum of the capacitance between the detection electrode 102 and the detection object 20 and the capacitance between the detection object 20 and the side ground electrode 104. Therefore, the capacitance-type sensor 100 according to the first embodiment can detect the detection object 20 having a low conductivity or dielectric constant with high sensitivity.

[0043] In the capacitance sensor 100 according to the first embodiment, the first side shield electrode 103 is disposed between the detection electrode 102 and the side ground electrode 104 .

[0044] As a result, the capacitance type sensor 100 according to the first embodiment can increase the sensitivity of the detection circuit 120 by canceling out the above-mentioned parasitic capacitances, and can detect even minute changes in capacitance between the detection electrode 102 and the side ground electrode 104. As a result, the capacitance type sensor 100 according to the first embodiment can detect even a detection object 20 with a low dielectric constant by detecting a change in capacitance between the detection electrode 102 and the side ground electrode 104.

[0045] Furthermore, in the capacitance-type sensor 100 according to the first embodiment, the detection electrode 102, the side ground electrode 104, and the first side shield electrode 103 have a longitudinal direction in a first direction (the Y-axis direction) and further include a connection portion 100A with the lead wiring 11A provided at one end in the first direction (the end on the positive side of the Y-axis), the first side shield electrode 103 has two straight portions 103A arranged in parallel with the side ground electrode 104 and a connection portion 103B connecting the other ends in the first direction of the two straight portions 103A (the ends on the negative side of the Y-axis), and the detection electrode 102 has two straight portions 102A arranged in parallel with the side ground electrode 104 and a connection portion 102B connecting the other ends in the first direction of the two straight portions 102A (the ends on the negative side of the Y-axis).

[0046] As a result, the capacitance sensor 100 of the first embodiment does not need to form the lead wiring 11A in the detection area by pulling it together, as is the case with a mutual capacitance type capacitance sensor in which the drive electrode and the detection electrode are arranged crosswise in the front-to-back direction (Y-axis direction) and width direction (X-axis direction), and can eliminate the parasitic capacitance and noise generation of the lead wiring 11A in the detection area, thereby enabling the detection area to be expanded while maintaining high detection sensitivity and a high S / N ratio.

[0047] Furthermore, the capacitance sensor 100 according to the first embodiment prevents a phase shift of the first AC drive voltage V1 applied to the straight portion 102A of the detection electrode 102 and a phase shift of the second AC drive voltage V2 applied to the straight portion 103A of the first side shield electrode 103, thereby ensuring that the first AC drive voltage V1 and the second AC drive voltage V2 are in phase, reducing parasitic capacitance and stably ensuring a high S / N ratio of the detection signal.

[0048] Second Embodiment Next, a second embodiment will be described. The capacitance detection device 10-2 according to the second embodiment differs from the capacitance detection device 10 according to the first embodiment in that it includes a capacitance sensor 100-2 instead of the capacitance sensor 100.

[0049] (Configuration of Capacitive Sensor 100-2) Fig. 8 is an exploded plan view of the capacitive sensor 100-2 according to the second embodiment. Fig. 9 is a cross-sectional view of the capacitive sensor 100-2 according to the second embodiment.

[0050] As shown in FIGS. 8 and 9, the capacitance sensor 100-2 according to the second embodiment differs from the capacitance sensor 100 according to the first embodiment in that it further includes a second side shield electrode 105.

[0051] The second side shield electrode 105 is a thin-film electrode provided on the upper surface 101A of the substrate 101 and made of a conductive material such as metal, inorganic conductive oxide, or conductive resin. The second side shield electrode 105 has a strip shape that extends linearly in the front-to-rear direction (Y-axis direction) on the upper surface 101A of the substrate 101. As shown in FIGS. 8 and 9 , the capacitance sensor 100-2 according to the second embodiment includes two second side shield electrodes 105. The two second side shield electrodes 105 are provided outside the two linear portions 102A of the detection electrode 102 in the width direction (X-axis direction) of the capacitance sensor 100. In other words, the two second side shield electrodes 105 are provided on the outermost sides of the capacitance sensor 100 in the width direction (X-axis direction). The detection electrode 102, the first side shield electrode 103, and the side ground electrode 104 are provided between the two second side shield electrodes 105. Furthermore, the two second side shield electrodes 105 are arranged in parallel with the two straight portions 102A of the detection electrode 102, the two straight portions 103A of the first side shield electrode 103, and the side ground electrode 104. The second side shield electrodes 105 are electrically connected to the detection circuit 120. The second side shield electrode 105 is driven by application of a second AC drive voltage V2 from the detection circuit 120. The second side shield electrode 105 and the first side shield electrode 103 are also electrically connected to the back shield electrode 106. As a result, the second side shield electrode 105, the back shield electrode 106, and the first side shield electrode 103 are all applied with the second AC drive voltage V2 of the same frequency and phase from the detection circuit 120.

[0052] Furthermore, in the capacitance sensor 100-2, the two second side shield electrodes 105 are formed in a band shape at the outermost sides in the width direction (X-axis direction), but a single connection portion 105B (not shown) may be provided to connect the rear ends (negative side of the Y-axis) of the two second side shield electrodes 105, so that the second side shield electrode 105 is formed in a U-shape when viewed in a plan view from above (positive direction of the Z-axis).

[0053] As a result, the capacitance sensor 100-2 according to the second embodiment can prevent a phase shift of the second AC drive voltage V2 applied to the two second side shield electrodes 105, ensuring that the voltages are in phase, thereby reducing parasitic capacitance and stably ensuring a high S / N ratio for the detection signal.

[0054] (Parasitic Capacitance Generated in the Capacitive Sensor 100-2) FIG. 10 is a diagram showing parasitic capacitance generated in the capacitive sensor 100-2 according to the second embodiment. FIG. 10 is a schematic conceptual diagram illustrating the electrodes on one side in the width direction (positive or negative side of the X axis) of the side ground electrode 104 provided in the center in the width direction (X axis direction) in FIGS. 8 and 9 . As shown in FIG. 10 , the following parasitic capacitances are generated in the capacitive sensor 100-2 according to the second embodiment. The first side shield electrode 103 and the second side shield electrode 105 are electrically connected to the back shield electrode 106. The side ground electrode 104 is connected to the ground potential of the circuit board 11, similar to the detection circuit 120.

[0055] Parasitic capacitance between the detection electrode 102 and the ground potential: Crgl(a) Parasitic capacitance between the detection electrode 102 and the side ground electrode 104: Crgl(b) Parasitic capacitance between the detection electrode 102 and the back shield electrode 106 Crs(a) Parasitic capacitance between the detection electrode 102 and the first side shield electrode 103 Crs(b) Parasitic capacitance between the detection electrode 102 and the second side shield electrode 105 Crs(c) Parasitic capacitance between the side ground electrode 104 and the back shield electrode 106: Csg(a) Parasitic capacitance between the side ground electrode 104 and the first side shield electrode 103: Csg(b) Parasitic capacitance between the second side shield electrode 105 and the ground potential: Csg(c)

[0056] (Circuit Model of Capacitance Detection Device 10-2) Fig. 11 is a diagram showing a circuit model of the capacitance detection device 10-2 according to the second embodiment (when the detection target 20 is not present on the capacitance sensor 100-2). Fig. 12 is a diagram showing a circuit model of the capacitance detection device 10-2 according to the second embodiment (when the detection target 20 is present on the capacitance sensor 100-2).

[0057] 11 and 12 , the detection circuit 120-2 included in the capacitance detection device 10-2 according to the second embodiment is similar to the detection circuit 120 according to the first embodiment. The capacitance sensor 100-2 differs from the circuit model of the capacitance detection device 10 according to the first embodiment in that the back shield electrode 106 is electrically connected to the second side shield electrode 105, and the second side shield electrode 105 is electrically connected to the capacitance detection unit 121. The capacitance detection unit 121 included in the detection circuit 120-2 generates a second AC drive voltage V2 having the same frequency and phase as the first AC drive voltage V1 and applies the second AC drive voltage V2 to the first side shield electrode 103, the second side shield electrode 105, and the back shield electrode 106. Specifically, the second AC voltage circuit 70, which is the second AC power supply of the second drive circuit 121B shown in FIG. 7, generates a second AC drive voltage V2 having the same frequency and phase as the first AC drive voltage V1, and applies the second AC drive voltage V2 to the first side shield electrode 103, the second side shield electrode 105, and the back shield electrode 106 via the lead-out wiring 11A-2.

[0058] (Detection Operation of Capacitive Sensor 100-2) Similar to the capacitive sensor 100 according to the first embodiment, the capacitive sensor 100-2 according to the second embodiment configured as described above can detect the capacitance (Crg+Crg') of the detection object 20 using the detection electrodes 102. The detection circuit 120-2 according to the second embodiment can determine the placement state of the detection object 20 on the capacitive sensor 100-2 (presence or absence of the detection object 20, the number of the detection objects 20, etc.) based on the capacitance (Crg+Crg') of the detection object 20 detected by the detection electrodes 102.

[0059] Here, the capacitance sensor 100-2 according to the second embodiment has a first side shield electrode 103 and a second side shield electrode 105 arranged in parallel with the detection electrode 102 on the upper surface 101A of the substrate 101, and the first side shield electrode 103 and the second side shield electrode 105 are driven by a second AC drive voltage V2 having the same frequency and phase as the first AC drive voltage V1 applied to the detection electrode 102. The capacitance sensor 100-2 according to the second embodiment also has a back shield electrode 106 arranged on the lower surface 101B of the substrate 101 so as to face the detection electrode 102, and the back shield electrode 106 is driven by a second AC drive voltage V2 having the same frequency and phase as the first AC drive voltage V1 applied to the detection electrode 102.

[0060] As a result, in the capacitance sensor 100-2 according to the second embodiment, as shown in Figures 11 and 12, the sum of the current Irgl(b) flowing through the parasitic capacitance Crgl(b) between the detection electrode 102 and the side ground electrode 104 and the current Irgl(a) flowing through the parasitic capacitance Crgl(a) between the detection electrode 102 and the ground potential is offset by the sum of the current Irs-s(b) flowing through the parasitic capacitance Crs(b) between the first side shield electrode 103 and the detection electrode 102, the current Irs-s(c) flowing through the parasitic capacitance Crs(c) between the second side shield electrode 105 and the detection electrode 102, and the current Irs-b flowing through the parasitic capacitance Crs(a) between the back shield electrode 106 and the detection electrode 102.

[0061] This is because, in Figure 11, the capacitance detection unit 121 (first drive / detection circuit 121A) adjusts the amplitude of the first AC drive voltage V1 applied to the detection electrode 102 to be smaller than the amplitude of the second AC voltage so that the sum of the currents Irs-b, Irs-s(b), and Irs-s(c) flowing into the detection electrode 102 from the back shield electrode 106, the first side shield electrode 103, and the second side shield electrode 105, to which the second AC drive voltage V2 is applied, is equal to the sum of the currents Irgl(a) and Irgl(b) flowing out of the detection electrode 102.

[0062] Therefore, in the capacitance type sensor 100-2 of the second embodiment, the sum of the parasitic capacitance Crgl(b) between the detection electrode 102 and the side ground electrode 104 and the parasitic capacitance Crgl(a) between the detection electrode 102 and the ground potential can be offset by the sum of the parasitic capacitance Crs(b) between the first side shield electrode 103 and the detection electrode 102, the parasitic capacitance Crs(c) between the second side shield electrode 105 and the detection electrode 102, and the parasitic capacitance Crs(a) between the back shield electrode 106 and the detection electrode 102.

[0063] Therefore, the capacitance sensor 100-2 according to the second embodiment can more effectively allocate the ratios of the currents (Irs-b, Irs-s(b), Irs-s(c)) flowing through the parasitic capacitances Crs(a), Crs(b), and Crs(c) between the detection electrode 102 and each shield, due to the parasitic capacitance Crs(c) between the second side shield electrode 105 and the detection electrode 102, and can efficiently reduce the bias in the attenuation ratio of the parasitic capacitances Crgl(a) and Crgl(b) of the detection electrode 102. In particular, the capacitance sensor 100-2 according to the second embodiment can increase the attenuation ratio of the parasitic capacitance Crgl(a) between the detection electrode 102 and the ground potential, thereby efficiently and substantially achieving a high S / N ratio of the detection signal.

[0064] Furthermore, in the capacitance sensor 100-2 according to the second embodiment, the second side shield electrode 105 is provided in parallel with the outer side (X-axis direction) of the detection electrode 102, and thus the second side shield electrode 105 to which the second AC drive voltage V2 is applied can prevent external noise from flowing into the detection electrode 102 from the outside in the width direction of the capacitance sensor 100-2 (X-axis direction). This allows the capacitance sensor 100-2 according to the second embodiment to have improved resistance to external noise. Therefore, the capacitance sensor 100-2 according to the second embodiment can improve the stability of the high S / N ratio of the detection signal compared to the capacitance sensor 100 according to the first embodiment.

[0065] As described above, in the capacitance sensor 100-2 according to the second embodiment, when no detection object 20 is present on the capacitance sensor 100-2 as shown in FIG. 11 , the parasitic capacitance Crgl (Crgl(a) + Crgl(b)) generated between the detection electrode 102 and the ground potential and between the detection electrode 102 and the side ground electrode 104 can be offset by the parasitic capacitances (Crs(a) + Crs(b) + sCrs(c)) of the first side shield electrode 103, the second side shield electrode 105, and the back shield electrode 106. As shown in FIG. 12 , when a detection object 20 is present on the capacitance sensor 100-2, the capacitance detected by the detection electrode 102 is the capacitance (Crg + Crg') of the detection object 20, with the parasitic capacitance Crgl eliminated. Therefore, the capacitance sensor 100-2 according to the second embodiment can improve the detection accuracy of the detection object 20 by the detection electrode 102. The capacitance (Crg+Crg') of the detection object 20 detected by the detection electrode 102 is detected by the first drive and detection circuit 121A as a change Ie in the current Is.

[0066] 12 , when the detection object 20 is present, the capacitance type sensor 100-2 according to the second embodiment generates a capacitance Crg between the detection electrode 102 and the detection object 20, and generates a capacitance Crg' between the detection object 20 and the side ground electrode 104. Therefore, when the detection object 20 is present, the capacitance type sensor 100-2 according to the second embodiment amplifies the capacitance of the detection object 20 detected by the detection electrode 102 to the sum of the capacitance Crg and the capacitance Crg', thereby improving the detection accuracy of the detection object 20 by the detection electrode 102.

[0067] (Detection Example of Detection Target 20 by Capacitive Sensor 100-2) FIG. 13 is a diagram showing an example of detection of the detection target 20 by the capacitive sensor 100-2 according to the second embodiment.

[0068] 13 , on the capacitance sensor 100-2 according to the second embodiment, the detection object 20 is placed across the detection electrode 102 to which the first AC voltage V1 is applied by the first drive / detection circuit 121A and the side ground electrode 104 connected to the ground potential. Therefore, the capacitance of the detection object 20 that is actually detected by the detection electrode 102 connected to the first drive / detection circuit 121A is the sum of the capacitance Crg between the detection electrode 102 and the detection object 20 and the capacitance Crg′ between the detection object 20 and the side ground electrode 104. Therefore, the capacitance sensor 100-2 according to the second embodiment can detect the detection object 20 with high sensitivity using the detection electrode 102.

[0069] In addition, in Figure 13, the capacitance (Crg + Crg') of the object to be detected 20 is shown only as the capacitance value between the side ground electrode 104 located in the center in the width direction (X-axis direction) and the detection electrode 102 located to the right of it (positive side of the X-axis).

[0070] 13, in the capacitance sensor 100-2 according to the second embodiment, when the detection object 20 straddles the side ground electrode 104 at the center in the width direction (X-axis direction) and both the detection electrode 102 on the right side (positive side of the X-axis) and the detection electrode 102 on the left side (negative side of the X-axis), the capacitance value is about twice the value of (Crg+Crg') because the area of ​​the detection electrode 102 facing the detection object 20 is about twice the area of ​​one detection electrode 102. This is also true for the capacitance sensor 100 according to the first embodiment.

[0071] Furthermore, as shown in FIG. 13 , the capacitance sensor 100-2 according to the second embodiment has detection electrodes 102 on both the left and right sides (positive and negative sides in the X-axis direction) of the side ground electrode 104. This allows the detection object 20 to be placed across the side ground electrode 104 and one of the detection electrodes 102 provided in the sliding direction, even when the user slides the detection object 20 to either side (positive or negative side in the X-axis direction) of the capacitance sensor 100-2. This allows the capacitance sensor 100-2 according to the second embodiment to reliably detect the presence or absence of the detection object 20. This is also true for the capacitance sensor 100 according to the first embodiment.

[0072] As described above, the capacitance sensor 100-2 according to the second embodiment further includes a second side shield electrode 105 arranged in parallel with the detection electrode 102 on one surface of the substrate 101, the detection electrode 102 being disposed between the first side shield electrode 103 and the second side shield electrode 105, and a second AC drive voltage V2 is applied to the second side shield electrode 105.

[0073] As a result, the capacitance sensor 100-2 according to the second embodiment can prevent noise from entering the detection electrode 102 from the direction of the second side shield electrode 105, ensuring high detection sensitivity with a high S / N ratio. Furthermore, the capacitance sensor 100-2 according to the second embodiment can effectively distribute the ratios of the currents (Irs-b, Irs-s(b), Irs-s(c)) flowing through the parasitic capacitances Crs(a), Crs(b), and Crs(c) between the detection electrode 102 and each shield, thereby efficiently reducing the bias in the attenuation ratio of the parasitic capacitances Crgl(a) and Crgl(b) of the detection electrode 102. In particular, the capacitance sensor 100-2 according to the second embodiment can increase the attenuation ratio of the parasitic capacitance Crgl(a) between the detection electrode 102 and the ground potential, thereby efficiently and substantially achieving a high S / N ratio of the detection signal.

[0074] Third Embodiment Next, a third embodiment will be described. The capacitance detection device 10-3 according to the third embodiment differs from the capacitance detection device 10-2 according to the second embodiment in that it includes a capacitance sensor 100-3 instead of the capacitance sensor 100-2.

[0075] (Configuration of Capacitive Sensor 100-3) Fig. 14 is an exploded plan view of the capacitive sensor 100-3 according to the third embodiment. Fig. 15 is a cross-sectional view of the capacitive sensor 100-3 according to the third embodiment.

[0076] As shown in FIGS. 14 and 15, the capacitance sensor 100-3 according to the third embodiment differs from the capacitance sensor 100-2 according to the second embodiment in that it further includes a background electrode 108.

[0077] The background electrode 108 is a sheet- or plate-shaped electrode made of a conductive material such as metal, inorganic conductive oxide, or conductive resin, and is provided below (on the negative side of the Z axis) the back shield electrode 106, spaced apart from and facing the back shield electrode 106. The background electrode 108 has the same shape (i.e., rectangular) as the back shield electrode 106 when viewed from above (positive direction of the Z axis) so as to face the entire back shield electrode 106. The background electrode 108 also has a larger area (or volume) than the side ground electrode 104. The background electrode 108 is also connected to the ground potential. Therefore, the background electrode 108 has a larger ground potential capacitance than the side ground electrode 104. The background electrode 108 is also electrically connected to the side ground electrode 104.

[0078] (Circuit Model of Capacitance Detection Device 10-3) Fig. 16 is a diagram showing a circuit model of the capacitance detection device 10-3 according to the third embodiment (when the detection target 20 is not present on the capacitance sensor 100-3). Fig. 17 is a diagram showing a circuit model of the capacitance detection device 10-3 according to the third embodiment (when the detection target 20 is present on the capacitance sensor 100-3).

[0079] As shown in Figures 16 and 17, the capacitance sensor 100-3 provided in the capacitance detection device 10-3 according to the third embodiment differs from the capacitance sensor 100-2 provided in the capacitance detection device 10-2 according to the second embodiment in that the capacitance sensor 100-3 further includes a background electrode 108, thereby generating a parasitic capacitance Csg(d) between the back shield electrode 106 and the background electrode 108, the side ground electrode 104 is electrically connected to the background electrode 108, and the background electrode 108 is connected to the ground potential of the circuit board 11 in the same manner as the detection circuit 120.

[0080] The detection circuit 120-3 provided in the capacitance detection device 10-3 according to the third embodiment is similar to the detection circuit 120-2 provided in the capacitance detection device 10-2 according to the second embodiment and the detection circuit 120 provided in the capacitance detection device 10 according to the first embodiment.

[0081] (Detection Operation of Capacitive Sensor 100-3) Similar to the capacitive sensor 100-2 according to the second embodiment, the capacitive sensor 100-3 according to the third embodiment configured as described above can detect the capacitance (Crg+Crg') of the detection object 20 using the detection electrodes 102. The detection circuit 120-3 according to the third embodiment can determine the placement state of the detection object 20 on the capacitive sensor 100-3 (presence or absence of the detection object 20, the number of the detection objects 20, etc.) based on the capacitance (Crg+Crg') of the detection object 20 detected by the detection electrodes 102.

[0082] Here, the capacitance sensor 100-3 according to the third embodiment has a first side shield electrode 103 and a second side shield electrode 105 arranged in parallel with the detection electrode 102 on the upper surface 101A of the substrate 101, and the first side shield electrode 103 and the second side shield electrode 105 are driven by a second AC drive voltage V2 having the same frequency and phase as the first AC drive voltage V1 applied to the detection electrode 102. The capacitance sensor 100-3 according to the third embodiment also has a back shield electrode 106 arranged on the lower surface 101B of the substrate 101 so as to face the detection electrode 102, and the back shield electrode 106 is driven by a second AC drive voltage V2 having the same frequency and phase as the first AC drive voltage V1 applied to the detection electrode 102.

[0083] As a result, in the capacitance sensor 100-3 of the third embodiment, as shown in Figures 16 and 17, the sum of the current Irgl(b) flowing through the parasitic capacitance Crgl(b) between the detection electrode 102 and the side ground electrode 104 and the current Irgl(a) flowing through the parasitic capacitance Crgl(a) between the detection electrode 102 and the ground potential is offset by the sum of the current Irs-s(b) flowing through the parasitic capacitance Crs(b) between the first side shield electrode 103 and the detection electrode 102, the current Irs-s(c) flowing through the parasitic capacitance Crs(c) between the second side shield electrode 105 and the detection electrode 102, and the current Irs-b flowing through the parasitic capacitance Crs(a) between the back shield electrode 106 and the detection electrode 102.

[0084] This is because, in Figure 16, the capacitance detection unit 121 (first drive / detection circuit 121A) adjusts the amplitude of the first AC drive voltage V1 applied to the detection electrode 102 to be smaller than the amplitude of the second AC voltage so that the sum of the currents Irs-b, Irs-s(b), and Irs-s(c) flowing into the detection electrode 102 from the back shield electrode 106, the first side shield electrode 103, and the second side shield electrode 105 to which the second AC drive voltage V2 is applied is equal to the sum of the currents Irgl(a) and Irgl(b) flowing out of the detection electrode 102.

[0085] Therefore, in the capacitance type sensor 100-3 of the third embodiment, the sum of the parasitic capacitance Crgl(b) between the detection electrode 102 and the side ground electrode 104 and the parasitic capacitance Crgl(a) between the detection electrode 102 and the ground potential can be offset by the sum of the parasitic capacitance Crs(b) between the first side shield electrode 103 and the detection electrode 102, the parasitic capacitance Crs(c) between the second side shield electrode 105 and the detection electrode 102, and the parasitic capacitance Crs(a) between the back shield electrode 106 and the detection electrode 102.

[0086] Therefore, the capacitance sensor 100-3 according to the third embodiment can more effectively allocate the ratios of the currents (Irs-b, Irs-s(b), Irs-s(c)) flowing through the parasitic capacitances Crs(a), Crs(b), and Crs(c) between the detection electrode 102 and each shield, due to the parasitic capacitance Crs(c) between the second side shield electrode 105 and the detection electrode 102, and can efficiently reduce the bias in the attenuation ratio of the parasitic capacitances Crgl(a) and Crgl(b) of the detection electrode 102. In particular, the capacitance sensor 100-3 according to the third embodiment can increase the attenuation ratio of the parasitic capacitance Crgl(a) between the detection electrode 102 and the ground potential, thereby efficiently and substantially achieving a high S / N ratio of the detection signal.

[0087] Furthermore, in the capacitance sensor 100-3 according to the third embodiment, the second side shield electrode 105 is provided in parallel with the outer side (X-axis direction) of the detection electrode 102, and thus the second side shield electrode 105 to which the second AC drive voltage V2 is applied can prevent external noise from the outer side in the width direction (X-axis direction) of the capacitance sensor 100-3 from flowing into the detection electrode 102. This allows the capacitance sensor 100-3 to have improved resistance to external noise. Therefore, the capacitance sensor 100-3 according to the third embodiment can improve the stability of the high S / N ratio of the detection signal compared to the capacitance sensor 100 according to the first embodiment.

[0088] As described above, in the capacitance sensor 100-3 according to the third embodiment, when no detection object 20 is present on the capacitance sensor 100-3 as shown in FIG. 16 , the parasitic capacitance Crgl (Crgl(a) + Crgl(b)) generated between the detection electrode 102 and the ground potential and between the detection electrode 102 and the side ground electrode 104 can be reduced by the parasitic capacitances (Crs(a) + Crs(b) + sCrs(c)) of the first side shield electrode 103, the second side shield electrode 105, and the back shield electrode 106. As shown in FIG. 17 , when a detection object 20 is present on the capacitance sensor 100-3, the capacitance detected by the detection electrode 102 is substantially the capacitance (Crg + Crg') of the detection object 20, with the parasitic capacitance Crgl (Crgl(a) + Crgl(b)) largely eliminated. This further improves the detection accuracy of the detection electrode 102 for the detection object 20. The capacitance (Crg+Crg') of the detection object 20 detected by the detection electrode 102 is detected by the first drive and detection circuit 121A as a change Ie in the current Is.

[0089] 17 , when the detection object 20 is present, the capacitance type sensor 100-3 according to the third embodiment generates a capacitance Crg between the detection electrode 102 and the detection object 20, and generates a capacitance Crg' between the detection object 20 and the side ground electrode 104. Therefore, when the detection object 20 is present, the capacitance type sensor 100-3 according to the third embodiment amplifies the capacitance of the detection object 20 detected by the detection electrode 102 to the sum of the capacitance Crg and the capacitance Crg', thereby improving the detection accuracy of the detection object 20 by the detection electrode 102.

[0090] Additionally, the capacitance sensor 100-3 according to the third embodiment has a larger area (or volume) and a larger ground potential capacity than the side ground electrode 104. By including a background electrode 108 connected to the ground potential, the capacitance sensor 100-3 according to the third embodiment can effectively attenuate external electromagnetic noise from below (the negative Z-axis direction). Furthermore, by including a background electrode 108 electrically connected to the side ground electrode 104, the capacitance sensor 100-3 according to the third embodiment can improve resistance to external noise compared to the capacitance sensor 100-2 according to the second embodiment. Therefore, the capacitance sensor 100-3 according to the third embodiment can improve the stability of the potential of the side ground electrode 104 and can prevent noise from entering the detection electrode 102 compared to the capacitance sensor 100-2 according to the second embodiment, thereby improving the stability of the high S / N ratio of the detection signal.

[0091] (Detection Example of Detection Target 20 by Capacitive Sensor 100-3) FIG. 18 is a diagram showing an example of detection of the detection target 20 by the capacitive sensor 100-3 according to the third embodiment.

[0092] 18 , on the capacitance sensor 100-3 according to the third embodiment, the detection object 20 is placed across the detection electrode 102 to which the first AC voltage V1 is applied by the first drive / detection circuit 121A and the side ground electrode 104, which is electrically connected to the ground potential together with the background electrode 108. Therefore, the capacitance of the detection object 20 that is substantially detected by the detection electrode 102 connected to the first drive / detection circuit 121A is the sum of the capacitance Crg between the detection electrode 102 and the detection object 20 and the capacitance Crg′ between the detection object 20 and the side ground electrode 104. Therefore, the capacitance sensor 100-3 according to the third embodiment can detect the detection object 20 with high sensitivity using the detection electrode 102. 18, the capacitance sensor 100-3 according to the third embodiment includes a background electrode 108 connected to the side ground electrode 104, and therefore can effectively attenuate external electromagnetic noise from below (the negative direction of the Z axis), thereby improving resistance to external noise. Therefore, the capacitance sensor 100-3 according to the third embodiment can improve the stability of the ground potential of the side ground electrode 104 and can prevent noise from entering the detection electrode 102, thereby improving the stability of the high S / N ratio of the detection signal compared to the capacitance sensor 100-2 according to the second embodiment.

[0093] In addition, in Figure 18, the capacitance (Crg + Crg') of the object to be detected 20 is shown only as the capacitance value between the side ground electrode 104 located in the center in the width direction (X-axis direction) and the detection electrode 102 located to the right of it (positive side of the X-axis).

[0094] As shown in Figure 18, in the capacitance sensor 100-3 of the third embodiment, when the object to be detected 20 straddles the side ground electrode 104 in the center in the width direction (X-axis direction) and both the detection electrode 102 on the right side (positive side of the X-axis) and the detection electrode 102 on the left side (negative side of the X-axis), the capacitance value is approximately twice (Crg + Crg') because the area of ​​the detection electrode 102 facing the object to be detected 20 is approximately twice that of one detection electrode 102.

[0095] 18 , the capacitance sensor 100-3 according to the third embodiment is provided with detection electrodes 102 on both the left and right sides (positive and negative sides in the X-axis direction) of the side ground electrode 104. This means that even if a user slides the detection object 20 to either side (positive or negative side in the X-axis direction) of the capacitance sensor 100-3 in the width direction (X-axis direction), the detection object 20 can be placed across the side ground electrode 104 and one of the detection electrodes 102 provided in the sliding direction, and the capacitance (Crg+Crg′) of the detection object 20 can be detected. This ensures that the capacitance sensor 100-3 according to the third embodiment can reliably detect the presence or absence of the detection object 20.

[0096] As described above, the capacitance sensor 100-3 according to the third embodiment further includes a background ground electrode 108 that is provided on the other surface of the substrate 101, spaced apart from and facing the back shield electrode 106, and that is connected to the side ground electrode 104.

[0097] As a result, the capacitance sensor 100 of the third embodiment can stabilize the potential of the side ground electrode 104 and prevent noise from flowing into the detection electrode 102, thereby improving the stability of the high S / N ratio of the output signal from the detection electrode 102.

[0098] Comparative Example A conventional capacitance sensor 910 will now be described as a comparative example.

[0099] (Configuration of Conventional Capacitive Sensor 910) Fig. 19 is an exploded plan view of a conventional capacitive sensor 910. Fig. 20 is a cross-sectional view of the conventional capacitive sensor 910.

[0100] As shown in FIGS. 19 and 20, a conventional capacitance sensor 910 includes a substrate 911 , a detection electrode 912 , a side shield electrode 913 , a back shield electrode 916 , a cover 917 , and a background electrode 918 .

[0101] The substrate 911, back shield electrode 916, cover 917, and background electrode 918 included in the conventional capacitance sensor 910 are similar to the substrate 101, back shield electrode 106, cover 107, and background electrode 108 included in the capacitance sensor 100-3 according to the third embodiment. The background electrode 918 is connected to the ground potential of the circuit board, similar to the detection circuit 920.

[0102] Furthermore, the conventional capacitance sensor 910 differs from the capacitance sensor 100-3 according to the third embodiment in that it does not have a detection electrode 102, a first side shield electrode 103, a side ground electrode 104, and a second side shield electrode 105, but instead has a detection electrode 912 and a side shield electrode 913.

[0103] The detection electrode 912 is a thin-film electrode formed on the upper surface 911A of the substrate 911 and made of a conductive material such as metal, inorganic conductive oxide, or conductive resin. The detection electrode 912 has a strip shape that extends linearly in the front-to-rear direction (Y-axis direction) on the upper surface 911A of the substrate 911. In the example shown in FIGS. 19 and 20 , the detection electrode 912 is provided in the center of the capacitance sensor 910 in the width direction (X-axis direction), i.e., between two linear portions 913A of the side shield electrode 913. As a result, the detection electrode 912 is arranged in parallel with the two linear portions 913A of the side shield electrode 913. The detection electrode 912 is electrically connected to the detection circuit 920. The detection electrode 912 is driven by application of a first AC drive voltage V1 from the detection circuit 920.

[0104] The side shield electrode 913 is a thin-film electrode provided on the upper surface 911A of the substrate 911 and made of a conductive material such as metal, inorganic conductive oxide, or conductive resin. The side shield electrode 913 has two linear portions 913A extending linearly in the front-to-rear direction (Y-axis direction) and two connecting portions 913B extending linearly in the left-to-right direction (X-axis direction) and connecting the front (positive Y-axis direction) and rear (negative Y-axis) ends of the two linear portions 913A. As a result, the side shield electrode 913 has a rectangular frame shape when viewed from above (positive Z-axis direction). The detection electrode 912 is disposed between the two linear portions 913A of the side shield electrode 913. That is, the two linear portions 913A of the side shield electrode 913 are arranged parallel to the detection electrode 912. The side shield electrode 913 is electrically connected to the detection circuit 920. The side shield electrode 913 is driven by applying a second AC drive voltage V2 from the detection circuit 920.

[0105] (Circuit Model of Conventional Electrostatic Detection System 900) Fig. 21 is a diagram showing a circuit model of the conventional electrostatic detection system 900 (when the detection target 20 is not present on the conventional capacitance sensor 910). Fig. 22 is a diagram showing a circuit model of the conventional electrostatic detection system 900 (when the detection target 20 is present on the conventional capacitance sensor 910).

[0106] As shown in FIGS. 21 and 22 , a conventional electrostatic detection system 900 includes a capacitance sensor 910 and a detection circuit 920. The detection circuit 920 is similar to the detection circuit 120 according to the first embodiment, the detection circuit 120-2 according to the second embodiment, and the detection circuit 120-3 according to the third embodiment. Accordingly, the detection circuit 920 includes a capacitance detection unit, a processing unit, and an I / F (all of which are not shown). The detection electrode 912, the side shield electrode 913, and the back shield electrode 916 of the capacitance sensor 910 are electrically connected to the capacitance detection unit of the detection circuit 920. The side shield electrode 913 and the back shield electrode 916 are electrically connected to each other. The capacitance detection unit of the detection circuit 920 includes a first drive / detection circuit and a second drive circuit (all of which are not shown), similar to the capacitance detection unit 121 shown in FIG. 16 . The first drive / detection circuit of the detection circuit 920 generates a first AC drive voltage V1 and applies the first AC drive voltage V1 to the detection electrode 912. The first drive / detection circuit of the detection circuit 920 also acquires the capacitance Crg of the detection object 20 detected by the detection electrode 912. The second drive circuit of the detection circuit 920 also generates a second AC drive voltage V2 having the same frequency and phase as the first AC drive voltage V1 and applies the second AC drive voltage V2 to the side shield electrode 913 and the back shield electrode 916.

[0107] 7, similar to the detection circuit 120 according to the first embodiment, the detection circuit 120-2 according to the second embodiment, and the detection circuit 120-3 according to the third embodiment. The first drive / detection circuit 121A of the detection circuit 920 is connected to the detection electrode 912 via a lead-out wiring similar to the lead-out wiring 11A-1 shown in FIG. 7. The second drive circuit of the detection circuit 920 is electrically connected to the side shield electrode 913 and the back shield electrode 916 via a lead-out wiring similar to the lead-out wiring 11A-2 shown in FIG.

[0108] (Detection Operation of Conventional Capacitive Sensor 910) In the conventional capacitive sensor 910 configured as described above, the detection electrode 912 is driven by a first AC drive voltage V1 supplied from the detection circuit 920. As a result, in the conventional capacitive sensor 910, when the placement state of the detection object 20 on the conventional capacitive sensor 910 changes, the capacitance Crg of the detection object 20 detected by the detection electrode 912 changes. Therefore, the detection circuit 920 can determine the placement state of the detection object 20 on the conventional capacitive sensor 910 (presence or absence of the detection object 20, the number of the detection objects 20, etc.) based on the capacitance Crg of the detection object 20 detected by the detection electrode 912.

[0109] Furthermore, the conventional capacitance sensor 910 has a side shield electrode 913 provided on an upper surface 911A of the substrate 911 in parallel with the detection electrode 912, and the side shield electrode 913 is driven by a second AC drive voltage V2 having the same frequency and phase as a first AC drive voltage V1 applied to the detection electrode 912. The conventional capacitance sensor 910 also has a back shield electrode 916 provided on a lower surface 911B of the substrate 911 so as to face the detection electrode 912, and the back shield electrode 916 is driven by a second AC drive voltage V2 having the same frequency and phase as the first AC drive voltage V1 applied to the detection electrode 912.

[0110] As a result, in the conventional capacitance sensor 910, as shown in Figures 21 and 22, the current Irgl(a) flowing through the parasitic capacitance Crgl(a) between the detection electrode 912 and the ground potential is offset by the sum of the current Irs-b flowing through the parasitic capacitance Crs(a) between the back shield electrode 916 and the detection electrode 912 and the current Irs-s flowing through the parasitic capacitance Crs(b) between the side shield electrode 913 and the detection electrode 912.

[0111] This is because, in Figure 21, the capacitance detection unit 121 (first drive / detection circuit 121A) of the detection circuit 920 adjusts the amplitude of the first AC drive voltage V1 applied to the detection electrode 912 to be smaller than the amplitude of the second AC voltage so that the sum of the currents Irs-b and Irs-s flowing into the detection electrode 912 from the back shield electrode 916 and side shield electrode 913 to which the second AC drive voltage V2 is applied is equal to the current Irgl(a) flowing out from the detection electrode 102.

[0112] Therefore, in the conventional capacitance sensor 910, the parasitic capacitance Crgl between the detection electrode 912 and the ground potential can be reduced by the sum of the parasitic capacitance Crs(a) between the back shield electrode 916 and the detection electrode 912 and the parasitic capacitance Crs(b) between the side shield electrode 913 and the detection electrode 912.

[0113] 21 , in a state where no detection object 20 is present on the conventional capacitance sensor 910, the parasitic capacitance Crgl(a) generated between the detection electrode 912 and the ground potential can be reduced by the parasitic capacitance (Crs(a)+Crs(b)) of the side shield electrode 913 and the back shield electrode 916. As shown in FIG. 22 , in a state where a detection object 20 is present on the conventional capacitance sensor 910, the capacitance detected by the detection electrode 912 is such that the parasitic capacitance Crgl(a) is largely eliminated, and the capacitance appears to be the capacitance of the detection object 20 (Crg+Crg'), which appears to improve the detection accuracy of the detection electrode 912 for the detection object 20.

[0114] However, the conventional capacitance sensor 910 differs from the capacitance sensor 100-3 according to the third embodiment in that it does not include a side ground electrode 104. Therefore, as shown in FIG. 22 , when a detection target 20 is present in the conventional capacitance sensor 910, a capacitance Crg is generated between the detection electrode 912 and the detection target 20, and a capacitance Crg' is generated between the detection target 20 and ground potential. However, because the distance between the detection target 20 and ground potential is large, the capacitance Crg' is extremely small. Therefore, when a detection target 20 is present in the conventional capacitance sensor 910, the capacitance of the detection target 20 that is substantially detected by the detection electrode 912 is only the capacitance Crg, and therefore the detection accuracy of the detection target 20 by the detection electrode 912 cannot be improved.

[0115] (Detection Example of Detection Target 20 by Conventional Capacitive Sensor 910) FIG. 23 is a diagram showing an example of detection of a detection target 20 by a conventional capacitive sensor 910. In FIG.

[0116] As shown in FIG. 23 , in a conventional capacitance sensor 910, a detection object 20 is placed on a detection electrode 912 to which a first AC voltage V1 is applied by a first drive / detection circuit 121A of a detection circuit 920. Therefore, a capacitance Crg is generated between the detection electrode 912 and the detection object 20. Also, as shown in FIG. 23 , a capacitance Crg' is generated between the detection object 20 and ground potential. However, because the distance between the detection object 20 and ground potential is large, the capacitance Crg' is extremely small. Therefore, the capacitance of the detection object 20 that is actually detected by the detection electrode 912 is the capacitance Crg between the detection electrode 912 and the detection object 20. Therefore, the conventional capacitance sensor 910 cannot detect the detection object 20 with high sensitivity using the detection electrode 912. Therefore, the conventional capacitance sensor 910 cannot detect a detection object 20 with low conductivity or dielectric constant with high sensitivity.

[0117] Experimental Example An experimental example using the capacitance sensor 100-3 according to the third embodiment and a conventional capacitance sensor 910 will be described below. In the capacitance sensor 100-3 according to the third embodiment, copper was used as the material for the side ground electrode 104, the detection electrode 102, the first side shield electrode 103, the second side shield electrode 105, and the back shield electrode 106, an aluminum plate was used as the material for the background electrode 108, and PMMA resin (polymethyl methacrylate resin) was used as the material for the cover 107 and the substrate 101. In the conventional capacitance sensor 910, copper was used as the material for the detection electrode 912 and the side shield electrode 913, an aluminum plate was used as the material for the back shield electrode 916, and PMMA resin (polymethyl methacrylate resin) was used as the material for the cover 917 and the substrate 911. FIG. 24 is a table listing the products used in the first and second experimental examples. FIG. 25 is a table showing a list of the detection results of the first and second experimental examples.

[0118] (First Experimental Example) In the first experimental example, a change in capacitance (amount of change in detection signal strength) accompanying a change in the display state of each of product A and product B on shelf board 21 of a product shelf shown in Fig. 24 was detected using capacitance sensor 100-3 according to the third embodiment and a conventional capacitance sensor 910. Specifically, the change in capacitance (amount of change in detection signal strength) when one product was removed from a row of products displayed was detected.

[0119] Product A: canned drinks (coffee, placed vertically): The number of cans displayed in one row was changed from five to four, with one can removed.

[0120] Product B: PET bottled beverage (water, placed vertically): The number of bottles displayed in one row was changed from four to three, with one bottle removed.

[0121] As shown in Figure 25, in the first experimental example, both the capacitance sensor 100-3 according to the third embodiment and the conventional capacitance sensor 910 were able to obtain a relatively high change in detection signal strength and a relatively high S / N ratio (20 dB or more) for both product A and product B.

[0122] Thus, in the first experimental example, changes in the display state of products (changes in detection signal strength) were detected with high sensitivity for both the capacitance sensor 100-3 according to the third embodiment and the conventional capacitance sensor 910. This is thought to be because products A and B used in the first experimental example were both beverages and therefore mainly water, and had relatively high electrical conductivity or dielectric constant, and therefore a sufficient capacitance value was obtained as the capacitance of the detection object 20, regardless of the presence or absence of the side ground electrode 104.

[0123] (Second Experimental Example) In the second experimental example, a change in capacitance (amount of change in detection signal strength) accompanying a change in the display state of each of products C to G on the shelf board 21 of a product shelf shown in Fig. 24 was detected using the capacitance sensor 100-3 according to the third embodiment and the conventional capacitance sensor 910. Specifically, the change in capacitance (amount of change in detection signal strength) when one product was removed from a row of products displayed was detected.

[0124] Product C: Boxed confectionery (gum, laid flat): The number of items displayed in one row was changed from two to one by removing one.

[0125] Product D: Boxed confectionery (caramel, laid flat): The number of items displayed in one row was changed from two to one by removing one.

[0126] Product E: Boxed sweets (caramel, placed vertically): The number of items displayed in one row was changed from two to one by removing one.

[0127] Product F: Bag snacks (cereal bars, laid flat): The number of items displayed in one row was changed from 1 to 0 by removing 1 item.

[0128] Product G: Bag snacks (cereal bars, placed vertically): The number of items displayed in one row was changed from 5 to 4 by removing one item.

[0129] As shown in Figure 25, in the second experimental example, the capacitance sensor 100-3 according to the third embodiment was able to obtain a sufficient change in detection signal strength and a sufficient S / N ratio (20 dB or more) for all of products C to G.

[0130] On the other hand, as shown in Figure 25, in the second experimental example, the conventional capacitance sensor 910 was unable to obtain a sufficient change in detection signal strength and a sufficient S / N ratio for all of products C to G.

[0131] Thus, in the second experimental example, the capacitance sensor 100-3 of the third embodiment was able to detect changes in the display state of products (changes in the detection signal strength) with high sensitivity, while the conventional capacitance sensor 910 was barely able to detect changes in the display state of products (changes in the detection signal strength).

[0132] Products C to G used in the second experimental example had little moisture and relatively low conductivity or dielectric constant, and therefore, since the capacitance sensor 100-3 according to the third embodiment has the side ground electrode 104, a sufficient capacitance value was obtained as the capacitance of the object to be detected 20, whereas the conventional capacitance sensor 910 did not have the side ground electrode 104 and therefore was unable to obtain a sufficient capacitance value as the capacitance of the object to be detected 20.

[0133] (Third Experimental Example) Fig. 26 is a table showing a list of products used in the third experimental example. Fig. 27 is a diagram showing a first example of the experimental procedure for the third experimental example. Fig. 28 is a diagram showing a second example of the experimental procedure for the third experimental example. Fig. 29 is a table showing a list of the detection results for the third experimental example.

[0134] In the third experimental example, the capacitance sensor 100-3 according to the third embodiment was used to detect a change in capacitance (change in the detection signal strength) associated with a change in the display state on the shelf 21 of the product shelf for each of product H and product I shown in Figure 26.

[0135] Product H: Paper-wrapped snacks in outer boxes (candy, placed flat, stacked two layers) Product I: Boxed snacks (snacks, placed vertically, stacked two layers)

[0136] The experiment for product H was conducted according to the experimental procedure shown in FIG. 27. Specifically, as shown in FIG. 27A, ten products H arranged in two rows and five columns inside an outer box were placed on a capacitance sensor 100-3 installed on a shelf 21. Next, as shown in FIG. 27B, one product H from the second row was removed from the outer box, and the capacitance sensor 100-3 detected a change in capacitance. Next, as shown in FIG. 27C, another product H from the first row was removed from the outer box, and the capacitance sensor 100-3 detected a change in capacitance.

[0137] Furthermore, an experiment was conducted on product I using the experimental procedure shown in Figure 28. Specifically, as shown in Figure 28A, five products I arranged in two tiers and three columns were placed on a capacitance sensor 100-3 installed on a shelf 21. Next, as shown in Figure 28B, one product I was removed from the second tier, and the capacitance sensor 100-3 detected a change in capacitance. Next, as shown in Figure 28C, another product I was removed from the first tier, and the capacitance sensor 100-3 detected a change in capacitance.

[0138] As shown in Figure 29, in the third experimental example, the capacitance sensor 100-3 of the third embodiment was able to obtain a sufficient change in detection signal strength and a sufficient S / N ratio (20 dB or more) for all products H and I, both when the products were taken out from the second tier and when the products were taken out from the first tier.

[0139] In particular, even though the products H and I used in the third experimental example had little moisture and relatively low conductivity or dielectric constant, the capacitance sensor 100-3 according to the third embodiment was able to obtain a sufficient change in detection signal strength and a sufficient S / N ratio (20 dB or higher) even when the products H and I were removed from the second row, which were farther away from the capacitance sensor 100-3. This is thought to be because the capacitance sensor 100-3 according to the third embodiment has the side ground electrode 104, and therefore was able to obtain a sufficient capacitance value as the capacitance of the object 20 to be detected.

[0140] [Modification]

[0141] (First Modification) Fig. 30 is an exploded plan view of a capacitance type sensor 100-4 according to a first modification, and Fig. 31 is a cross-sectional view of the capacitance type sensor 100-4 according to the first modification.

[0142] 30 and 31 , the capacitance sensor 100-4 according to the first modification includes a detection electrode 102 that extends linearly in the center in the left-right direction (X-axis direction). The capacitance sensor 100-4 also includes two linearly extending straight portions 103A of a first side shield electrode 103 on both outer sides of the detection electrode 102 in the left-right direction (X-axis direction). The first side shield electrode 103 has a connecting portion 103B that connects the rear ends (negative side of the Y-axis) of the two straight portions 103A together. As a result, the first side shield electrode 103 is formed in a U-shape surrounding the detection electrode 102 in a plan view from above (positive direction of the Z-axis).

[0143] The capacitance-type sensor 100-4 also includes two linear portions 104A of the side ground electrode 104, which extend linearly on both sides of the two linear portions 103A of the two first side shield electrodes 103 in the left-right direction (X-axis direction). The side ground electrode 104 has one connection portion 104B that connects the rear ends (negative side of the Y-axis) of the two linear portions 104A together. As a result, the side ground electrode 104 is formed in a U-shape surrounding the detection electrode 102 and the first side shield electrode 103 in a plan view from above (positive direction of the Z-axis). The side ground electrode 104 is electrically connected to the ground potential of the circuit board 11, similar to the detection circuit 120.

[0144] That is, the detection electrode 102 is arranged in parallel with the two straight line portions 103A of the first side shield electrode 103 and the two straight line portions 104A of the side ground electrode 104. The capacitance sensor 100-4 according to the first modification has a configuration in which the positions of the detection electrode 102 and the side ground electrode 104 of the capacitance sensor 100 according to the first embodiment are swapped.

[0145] The capacitance sensor 100-4 includes a substrate 101, a back shield electrode 106, and a cover 107, similar to the capacitance sensor 100 according to the first embodiment.

[0146] Furthermore, the detection circuit 120 connected to the capacitance sensor 100-4 according to the first modification is similar to the detection circuit 120 according to the first embodiment, and the capacitance detection unit 121 has the circuit configuration shown in Fig. 7. Therefore, in the capacitance sensor 100-4 according to the first modification, the detection electrode 102 is driven by application of a first AC drive voltage V1 from the detection circuit 120.

[0147] Furthermore, in the capacitance sensor 100-4 according to the first modification, the first side shield electrode 103 is electrically connected to the back shield electrode 106. As a result, in the capacitance sensor 100-4 according to the first modification, a second AC drive voltage V2 of the same frequency and phase is applied from the detection circuit 120 to both the back shield electrode 106 and the first side shield electrode 103.

[0148] The circuit model of the capacitance sensor 100-4 according to the first modification is the same as that described in the first embodiment (see FIGS. 5 and 6 ). Therefore, in the capacitance sensor 100-4 according to the first modification, the sum of the parasitic capacitance Crgl(b) between the detection electrode 102 and the side ground electrode 104 and the parasitic capacitance Crgl(a) between the detection electrode 102 and the ground potential can be offset by the sum of the parasitic capacitance Crs(b) between the first side shield electrode 103 and the detection electrode 102 and the parasitic capacitance Crs(a) between the back shield electrode 106 and the detection electrode 102.

[0149] (Detection Example of Detection Target 20 by Capacitive Sensor 100-4) FIG. 32 is a diagram showing an example of detection of the detection target 20 by the capacitive sensor 100-4 according to the first modified example.

[0150] 32 , on the capacitance sensor 100-4 according to the first modification, the detection object 20 is placed across the detection electrode 102 to which the first AC voltage V1 is applied by the first drive / detection circuit 121A and the side ground electrode 104 connected to the ground potential of the circuit board 11. Therefore, the capacitance of the detection object 20 that is substantially detected by the detection electrode 102 connected to the first drive / detection circuit 121A is the sum of the capacitance Crg between the detection electrode 102 and the detection object 20 and the capacitance Crg′ between the detection object 20 and the side ground electrode 104. Therefore, the capacitance sensor 100-4 according to the first modification can detect the detection object 20 with high sensitivity using the detection electrode 102.

[0151] Furthermore, the capacitance sensor 100-4 according to the first modification is provided with side ground electrodes 104 on both the left and right sides (positive and negative sides in the X-axis direction) of the detection electrode 102. This means that even if the user slides the detection object 20 to either side (positive or negative side of the X-axis) in the width direction (X-axis direction) of the capacitance sensor 100-2 and places it thereon, the detection object 20 can be placed across the detection electrode 102 and one of the side ground electrodes 104 provided in the sliding direction, and the detection object 20 can be detected by the capacitance (Crg+Crg') of the detection object 20. As a result, the capacitance sensor 100-4 according to the first modification can detect the presence or absence of the detection object 20 with the same capacitance value (Crg+Crg') regardless of whether the user slides the detection object 20 to either side in the width direction (X-axis direction) and places it thereon.

[0152] Furthermore, the capacitance sensor 100-4 according to the first modification has side ground electrodes 104 (104A) arranged in parallel on both outer sides (positive and negative sides of the X axis) of the detection electrode 102, so that the side ground electrodes 104 (104A) connected to the ground potential can prevent external noise from flowing into the detection electrode 102 from both outer sides in the width direction of the capacitance sensor 100-4 according to the first modification (positive and negative sides of the X axis). This allows the capacitance sensor 100-4 according to the first modification to have improved resistance to external noise. Therefore, the capacitance sensor 100-7 according to the first modification can improve the stability of the S / N ratio of the detection signal.

[0153] (Second Modification) Fig. 33 is a plan view of a capacitance type sensor 100-5 according to a second modification, and Fig. 34 is a cross-sectional view of the capacitance type sensor 100-5 according to the second modification.

[0154] The capacitance sensor 100-5 according to the second modification is a modification of the capacitance sensor 100 according to the first embodiment. In the capacitance sensor 100 according to the first embodiment, as a preferred example, a connection portion 102B is provided between the two straight portions 102A of the detection electrode 102, and a connection portion 103B is provided between the two straight portions 103A of the first side shield electrode, so that the detection electrode 102 and the first side shield electrode 103 are both U-shaped in plan view.

[0155] In contrast, the capacitance sensor 100-5 according to the second modified example has a basic unit structure in which a side ground electrode 104, a first side shield electrode 103, and a detection electrode 102, all of which are linear in plan view, are arranged side by side on the upper surface 101A of the substrate 101, one each as shown in Figures 33 and 34.

[0156] Therefore, the capacitance sensor 100-5 according to the second modification is the same as the capacitance sensor 100 according to the first embodiment, except that the detection electrode 102 and the first side shield electrode 103 are not U-shaped in plan view. Furthermore, the capacitance sensor 100-5 according to the second modification is connected to a detection circuit 120 that is similar to the detection circuit 120 according to the first embodiment. Therefore, the capacitance sensor 100-5 according to the second modification can exhibit the same functions as the capacitance sensor 100 according to the first embodiment, except that the detection electrode 102 and the first side shield electrode 103 are not U-shaped in plan view.

[0157] As described above, the capacitance-type sensor 100-5 according to the second modified example includes a substrate 101, a detection electrode 102 arranged on one surface of the substrate 101, a first side shield electrode 103 arranged in parallel with the detection electrode 102 on one surface of the substrate 101, and a back shield electrode 106 arranged on the other surface of the substrate 101 opposite the detection electrode 102 with the substrate 101 interposed therebetween, wherein a first AC drive voltage V1 is applied to the detection electrode 102, and a second AC drive voltage V2 having the same frequency and phase as the first AC drive voltage V1 is applied to the first side shield electrode 103 and the back shield electrode 106, and the capacitance-type sensor 100-5 according to the second modified example includes a side ground electrode 104 arranged in parallel with the detection electrode 102 and first side shield electrode 103 on one surface of the substrate 101 and connected to a ground potential.

[0158] As a result, the capacitance sensor 100-5 according to the second modification can detect the object 20 to be detected that has a low conductivity or dielectric constant with high sensitivity, similar to the capacitance sensor 100 according to the first embodiment.

[0159] In the capacitance sensor 100 - 5 according to the second modification, the first side shield electrode 103 is disposed between the detection electrode 102 and the side ground electrode 104 .

[0160] As a result, the capacitance type sensor 100-5 according to the second modification can increase the sensitivity of the detection circuit 120 by reducing the parasitic capacitances described above, and can detect even minute changes in capacitance between the detection electrode 102 and the side ground electrode 104. As a result, the capacitance type sensor 100-5 according to the second modification can detect even an object to be detected 20 with a low dielectric constant by changing the capacitance between the detection electrode 102 and the side ground electrode 104.

[0161] (Third Modification) Fig. 35 is a plan view of a capacitance type sensor 100-6 according to a third modification, and Fig. 36 is a cross-sectional view of the capacitance type sensor 100-6 according to the third modification.

[0162] The capacitance sensor 100-6 according to the third modification is a modification of the capacitance sensor 100-2 according to the second embodiment. In the capacitance sensor 100-2 according to the second embodiment, as a preferred example, a connection portion 102B is provided between the two straight portions 102A of the detection electrode 102, and a connection portion 103B is provided between the two straight portions 103A of the first side shield electrode, so that the detection electrode 102 and the first side shield electrode 103 are both U-shaped in plan view.

[0163] In contrast, the capacitance-type sensor 100-6 according to the third modified example has a basic unit structure in which a side ground electrode 104, a first side shield electrode 103, a detection electrode 102, and a second side shield electrode 105, all of which are linear in plan view, are arranged side by side on the upper surface 101A of the substrate 101, one each as shown in Figures 35 and 36.

[0164] Therefore, the capacitance sensor 100-6 according to the third modification is the same as the capacitance sensor 100-2 according to the second embodiment, except that the detection electrode 102 and the first side shield electrode 103 are not U-shaped in plan view. Furthermore, the capacitance sensor 100-6 according to the third modification is connected to the detection circuit 120 according to the first embodiment and a detection circuit 120 similar to the detection circuit 120-2 according to the second embodiment. Therefore, the capacitance sensor 100-6 according to the third modification can exhibit the same functions as the second embodiment, except that the detection electrode 102 and the first side shield electrode 103 are not U-shaped in plan view.

[0165] As described above, the capacitance sensor 100-6 according to the third modified example has a configuration in which, compared to the capacitance sensor 100-5 according to the second modified example, it further includes a second side shield electrode 105 arranged in parallel with the detection electrode 102 on one surface of the substrate 101, the detection electrode 102 being disposed between the first side shield electrode 103 and the second side shield electrode 105, and a second AC drive voltage V2 is applied to the second side shield electrode 105.

[0166] As a result, the capacitance sensor 100-6 according to the third modification can prevent noise from entering the detection electrode 102 from the direction of the second side shield electrode 105, ensuring high detection sensitivity with a high S / N ratio.

[0167] Furthermore, the capacitance sensor 100-6 according to the third modification can effectively distribute the ratios of the currents (Irs-b, Irs-s(b), Irs-s(c)) flowing through the parasitic capacitances Crs(a), Crs(b), and Crs(c) between the detection electrode 102 and each shield, and can efficiently reduce the bias in the attenuation ratio of the parasitic capacitances Crgl(a) and Crgl(b) of the detection electrode 102. In particular, the capacitance sensor 100-6 according to the third modification can increase the attenuation ratio of the parasitic capacitance Crgl(a) between the detection electrode 102 and the ground potential, and can efficiently and substantially achieve a high S / N ratio of the detection signal.

[0168] Furthermore, the capacitance sensor 100-6 according to the third modification has a side ground electrode 104 provided in parallel to the left side of the detection electrode 102 (the negative side of the X axis). This allows the side ground electrode 104, connected to ground potential, to prevent external noise from flowing into the detection electrode 102 from the left side in the width direction of the capacitance sensor 100-6 (the negative side of the X axis). Furthermore, the capacitance sensor 100-6 according to the third modification has a second side shield electrode 105 provided in parallel to the right side of the detection electrode 102 (the positive side of the X axis). This allows the second side shield electrode 105, to which the second AC drive voltage V2 is applied, to prevent external noise from flowing into the detection electrode 102 from the right side in the width direction of the capacitance sensor 100-6 (the positive side of the X axis). This allows the capacitance sensor 100-6 according to the third modification to have improved resistance to external noise. Therefore, the capacitance type sensor 100-6 according to the third modification can improve the stability of the S / N ratio of the detection signal.

[0169] (Fourth Modification) FIG. 37 is a cross-sectional view of a capacitance sensor 100-7 according to a fourth modification.

[0170] As shown in FIG. 37, the capacitance sensor 100-7 according to the fourth modified example has a side ground electrode 104, a detection electrode 102, and a second side shield electrode 105, all of which are linear in plan view, arranged side by side on the upper surface 101A of the substrate 101, and a back shield electrode 106 arranged opposite the detection electrode 102 on the lower surface 101B of the substrate 101.

[0171] Furthermore, the capacitance sensor 100-7 according to the fourth modification is connected to the same detection circuit 120-2 as the detection circuit 120-2 according to the second embodiment. The detection electrode 102 of the capacitance sensor 100-7 according to the fourth modification is driven by application of a first AC drive voltage V1 from the detection circuit 120-2.

[0172] In the capacitance sensor 100-7 according to the fourth modification, the second side shield electrode 105 and the back shield electrode 106 are driven by a second AC drive voltage V2 applied from the detection circuit 120-2. The second AC drive voltage V2 has the same frequency and phase as the first AC drive voltage V1 applied to the detection electrode 102. The second side shield electrode 105 and the back shield electrode 106 are electrically connected to each other. The side ground electrode 104 is connected to the ground potential of the circuit board 11, similar to the detection circuit 120-2.

[0173] The capacitance type sensor 100-7 according to the fourth modified example can offset the sum (Crgl(a) + Crgl(b)) of the parasitic capacitance between the detection electrode 102 and the ground potential and the parasitic capacitance between the detection electrode 102 and the side ground electrode 104 by the sum (Crs(a) + Crs(c)) of the parasitic capacitance between the detection electrode 102 and the back shield electrode 106 and the parasitic capacitance between the detection electrode 102 and the second side shield electrode 105.

[0174] Furthermore, the capacitance type sensor 100-7 according to the fourth modification can detect the capacitance (Crg+Crg') of the detection object 20 placed across the detection electrode 102 and the side ground electrode 104.

[0175] Furthermore, the capacitance sensor 100-7 according to the fourth modification has a side ground electrode 104 provided in parallel to the left side of the detection electrode 102 (negative side of the X axis). This allows the side ground electrode 104, connected to ground potential, to prevent external noise from flowing into the detection electrode 102 from the left side in the width direction (negative side of the X axis) of the capacitance sensor 100-6 according to the fourth modification. Furthermore, the capacitance sensor 100-7 according to the fourth modification has a second side shield electrode 105 provided in parallel to the right side of the detection electrode 102 (positive side of the X axis). This allows the second side shield electrode 105, to which the second AC drive voltage V2 is applied, to prevent external noise from flowing into the detection electrode 102 from the right side in the width direction (positive side of the X axis) of the capacitance sensor 100-7 according to the fourth modification. This allows the capacitance sensor 100-7 according to the fourth modification to have improved resistance to external noise. Therefore, the capacitance type sensor 100-7 according to the fourth modification can improve the stability of the S / N ratio of the detection signal.

[0176] (Fifth Modification) FIG. 38 is a cross-sectional view of a capacitance sensor 100-8 according to a fifth modification.

[0177] As shown in FIG. 38, the capacitance sensor 100-8 according to the fifth modified example has a side ground electrode 104 and a detection electrode 102, both of which are linear in plan view, arranged side by side on the upper surface 101A of the substrate 101, and a back shield electrode 106 arranged opposite the detection electrode 102 on the lower surface 101B of the substrate 101.

[0178] Furthermore, the capacitance sensor 100-8 according to the fifth modification is connected to the same detection circuit 120 as the detection circuit 120 according to the first embodiment. The detection electrode 102 of the capacitance sensor 100-8 according to the fifth modification is driven by application of a first AC drive voltage V1 from the detection circuit 120.

[0179] In the capacitance sensor 100-8 according to the fifth modification, the back shield electrode 106 is driven by applying a second AC drive voltage V2 from the detection circuit 120. The second AC drive voltage V2 has the same frequency and phase as the first AC drive voltage V1 applied to the detection electrode 102. The side ground electrode 104 is connected to the ground potential of the circuit board 11, similar to the detection circuit 120.

[0180] As a result, the capacitance sensor 100-8 according to the fifth modification can cancel out the sum (Crgl(a)+Crgl(b)) of the parasitic capacitance between the detection electrode 102 and the ground potential and the parasitic capacitance between the detection electrode 102 and the side ground electrode 104, with the parasitic capacitance (Crs(a)) between the detection electrode 102 and the back shield electrode 106. Therefore, the capacitance sensor 100-8 according to the fifth modification can detect the capacitance (Crg+Crg') of the detection object 20 placed across the detection electrode 102 and the side ground electrode 104.

[0181] (Sixth Modification) Fig. 39 is a cross-sectional view of a capacitance sensor 100-9 according to a sixth modification. As shown in Fig. 39, in the capacitance sensor 100-9 according to the sixth modification, the substrate 101 can be folded at a midpoint in the width direction (X-axis direction) so that two substrates 101 are stacked one on top of the other.

[0182] In the capacitance sensor 100-9 according to the sixth modification, the second side shield electrode 105 is extended significantly in the width direction (X-axis direction) on the upper surface 101A of the substrate 101. As a result, in the capacitance sensor 100-9 according to the sixth modification, when the substrate 101 is bent, as shown in FIG. 39 , a portion of the second side shield electrode 105 can be arranged to overlap the other electrodes (the detection electrode 102, the first side shield electrode 103, and the side ground electrode 104) below (on the negative side of the Z-axis). Therefore, in the capacitance sensor 100-9 according to the sixth modification, a portion of the second side shield electrode 105 can function similarly to the back shield electrode 106.

[0183] In other words, in the capacitance sensor 100-9 according to the sixth modified example, the back shield electrode 106 is formed integrally with the second side shield electrode 105, and the back shield electrode 106 (part of the second side shield electrode 105) can be formed together with the other electrodes on the upper surface 101A of the substrate 101, thereby simplifying the manufacturing process of the back shield electrode 106.

[0184] Furthermore, the capacitance sensor 100-9 according to the sixth modification can cover the side surface of the region between the detection electrode 102 and the back shield electrode 106 with a part of the second side shield electrode 105. This prevents external noise from flowing into the detection electrode 102 from the side surface of the region between the detection electrode 102 and the back shield electrode 106, thereby improving the sensitivity of the detection signal and the S / N ratio.

[0185] Furthermore, this enables the capacitance sensor 100-9 according to the sixth modified example to prevent a phase shift in the second AC drive voltage V2 applied between the second side shield electrode 105 and the back shield electrode 106, i.e., ensures that the second AC drive voltage V2 is in phase, thereby reducing parasitic capacitance and stabilizing a high S / N ratio of the detection signal.

[0186] In the example shown in Figure 39, the capacitance sensor 100-9 of the sixth modified example has a resin support plate 109 placed between two layers of substrate 101, and the substrate 101 is attached to the support plate 109 with an adhesive layer 110, thereby fixing the support plate 109 in a two-layer state.

[0187] In the example shown in FIG. 39, the entire upper surface 101A of the substrate 101 of the capacitance type sensor 100-9 according to the sixth modification is covered with a cover resist 111.

[0188] (Seventh Modification) Fig. 40 is a plan view of a capacitance detection device 10-4 according to a seventh modification. As shown in Fig. 40, the capacitance detection device 10-4 includes a sensor unit 13 made up of a plurality of sensor sheets 12 (four sensor sheets 12 in the example shown in Fig. 40) arranged side by side in the left-right direction (X-axis direction). Each of the four sensor sheets 12 included in the sensor unit 13 has a configuration similar to the sensor sheet 12 described in the first embodiment. That is, each of the four sensor sheets 12 included in the sensor unit 13 includes a plurality of capacitance sensors 100 (three capacitance sensors 100 in the example shown in Fig. 40) arranged side by side in the left-right direction (X-axis direction).

[0189] The detection circuit 120 included in the capacitance detection device 10-4 is connected to each of the multiple capacitance sensors 100 provided on the multiple sensor sheets 12. For example, in the example shown in Fig. 40, the detection circuit 120 included in the capacitance detection device 10-4 is connected to each of the 12 capacitance sensors 100. As a result, the detection circuit 120 included in the capacitance detection device 10-4 drives each of the 12 capacitance sensors 100, thereby enabling each of the 12 capacitance sensors 100 to detect the detection target 20 and enabling the detection results of the detection target 20 to be obtained from each of the 12 capacitance sensors 100.

[0190] The capacitance detection device 10-4 of the seventh variant is equipped with a sensor unit 13 having multiple sensor sheets 12. For example, by placing the sensor unit 13 on a shelf 21 of a product shelf, a larger number of capacitance sensors 100 can be used to detect the display status of products (presence or absence of products, number of products, etc.) in each of a larger number of product rows 21A using the self-capacitance method.

[0191] (Eighth Modification) Figure 41 is a plan view of a capacitance detection device 10-5 according to an eighth modification. As shown in Figure 41, the capacitance detection device 10-5 according to the eighth modification differs from the capacitance detection device 10 according to the first embodiment in that the base material 101 of the sensor sheet 12 is integrally formed with the circuit board 11. The circuit board 11 is formed of an insulating material such as glass epoxy resin, glass polyimide resin, paper epoxy resin, or paper phenolic resin. This makes it possible for the capacitance detection device 10-5 according to the eighth modification to prevent breakage of the sensor sheet 12 due to an impact when the detection object 20 is placed on the sensor sheet 12.

[0192] (Ninth Modification) Fig. 42 is a plan view of a capacitance detection device 10-6 according to a ninth modification. As shown in Fig. 42, the capacitance detection device 10-6 according to the ninth modification includes a plurality of capacitance detection devices 10-5 (four capacitance detection devices 10-5 in the example shown in Fig. 42) arranged side by side in the left-right direction (X-axis direction). Note that the capacitance detection device 10-6 according to the ninth modification differs from the capacitance detection device 10-4 according to the seventh modification in that each of the plurality of capacitance detection devices 10-5 includes a detection circuit 120.

[0193] (Supplementary Notes on the Fifth Modification) <Configuration of Capacitive Sensor 100-8> Fig. 43 is a plan view of a capacitive sensor 100-8 according to the fifth modification. Fig. 44 is a cross-sectional view of the capacitive sensor 100-8 according to the fifth modification.

[0194] As shown in Figures 43 and 44, the capacitance sensor 100-8 of the fifth modified example has a side ground electrode 104 and a detection electrode 102, both of which are linear in plan view, arranged side by side on the upper surface 101A of the substrate 101, and a back shield electrode 106 arranged opposite the detection electrode 102 on the lower surface 101B of the substrate 101.

[0195] That is, the capacitance sensor 100-8 according to the fifth modified example is a two-element capacitance sensor having a side ground electrode 104 and a detection electrode 102 on the upper surface 101A of the substrate 101, and is equivalent to the configuration of the three-element capacitance sensor 100-5 (see Figures 33 and 34) having a first side shield electrode 103, a side ground electrode 104, and a detection electrode 102 on the upper surface 101A of the substrate 101, with the first side shield electrode 103 removed.

[0196] 43 and 44, in the capacitance sensor 100-8 according to the fifth modification, the length of the detection electrode 102 in the longitudinal direction (axial direction) is defined as length L, and the width of the detection electrode 102 in the lateral direction (X-axis direction) is defined as width W. The distance between the side ground electrode 104 and the detection electrode 102 is defined as distance D. The thickness of the substrate 101 is defined as thickness T1. The thickness of the detection electrode 102 is defined as thickness T2.

[0197] <Circuit Model of Capacitance Detection Device 10-7> Fig. 45 is a diagram showing a circuit model of the capacitance detection device 10-7 according to the fifth modified example (when the detection object 20 is not present on the capacitance sensor 100-8). Fig. 46 is a diagram showing a circuit model of the capacitance detection device 10-7 according to the fifth modified example (when the detection object 20 is present on the capacitance sensor 100-8).

[0198] The circuit model of the capacitance detection device 10-7 shown in Figures 45 and 46 differs from the circuit model of the capacitance detection device 10 shown in Figures 5 and 6 in that it includes a capacitance sensor 100-8 (see Figures 43 and 44) ​​that does not have a first side shield electrode 103 instead of the capacitance sensor 100.

[0199] Therefore, in the capacitance detection device 10-7, the following parasitic capacitance occurs in the capacitance sensor 100-8, as shown in FIGS.

[0200] Parasitic capacitance between the detection electrode 102 and the ground potential: Crgl(a) Parasitic capacitance between the detection electrode 102 and the side ground electrode 104: Crgl(b) Parasitic capacitance between the detection electrode 102 and the back shield electrode 106: Crs(a) Parasitic capacitance between the side ground electrode 104 and the back shield electrode 106: Csg(a)

[0201] The detection circuit 120 provided in the circuit model of the capacitance detection device 10-7 shown in Figures 45 and 46 is the same as the detection circuit 120 provided in the circuit model of the capacitance detection device 10 shown in Figures 5 and 6, and the configuration example of the capacitance detection unit 121 of the detection circuit 120 shown in Figure 7.

[0202] In the capacitance detection device 10-7, the detection electrode 102 is driven by applying a first AC drive voltage V1 from a first drive / detection circuit 121A of the detection circuit 120.

[0203] In addition, in the capacitance detection device 10-7, the back shield electrode 106 is driven by applying a second AC drive voltage V2 having the same frequency and phase as the first AC drive voltage V1 from the second drive circuit 121B of the detection circuit 120.

[0204] In the capacitance detection device 10-7, the first drive / detection circuit 121A of the detection circuit 120 detects the change Ie in the current Is flowing through the detection electrode 102 as a change in capacitance in the detection electrode 102, and outputs a detection signal Ds based on the change Ie in the current Is.

[0205] Here, the capacitance detection device 10-7 can offset the sum (Crgl(a) + Crgl(b)) of the parasitic capacitance between the detection electrode 102 and the ground potential and the parasitic capacitance between the detection electrode 102 and the side ground electrode 104 with the parasitic capacitance (Crs(a)) between the detection electrode 102 and the back shield electrode 106.

[0206] Therefore, in the capacitance detection device 10-7, when the object to be detected 20 is placed across the detection electrode 102 and the side ground electrode 104 (see Figure 46), the capacitance detected by the detection electrode 102 is essentially the capacitance (Crg + Crg') of the object to be detected 20, and therefore the capacitance (Crg + Crg') of the object to be detected 20 can be detected with high sensitivity as a change Ie in the current Is.

[0207] As described above, the capacitance sensor 100-8 according to the fifth modified example has a two-element configuration in which the detection electrode 102 and the side ground electrode 104 are provided on the upper surface 101A of the substrate 101, and the first side shield electrode 103 is not provided.

[0208] As a result, when compared with a conventional capacitance sensor 910 (see Figures 19 and 20) that does not have a side ground electrode 104, the capacitance sensor 100-8 of the fifth modified example has a short distance between the object to be detected 20 and the ground potential, so that the capacitance Crg' between the object to be detected 20 and the ground potential can be made sufficiently large.In other words, the capacitance (Crg + Crg') of the object to be detected 20 detected by the detection electrode 102 can be made sufficiently large, so that the detection accuracy of the object to be detected 20 by the detection electrode 102 can be improved.

[0209] Therefore, the capacitance sensor 100-8 according to the fifth variant can detect changes in the display state of the object to be detected 20 with high sensitivity and high SNR even under unfavorable conditions for electrostatic detection of the object to be detected 20 (for example, when the surface on which the object to be detected 20 is placed is separated from the detection electrode 102, or when the conductivity or dielectric constant of the object to be detected 20 is low, etc.), and further can increase the dynamic range of the output voltage Vo of the operational amplifier 30 in Figure 7.

[0210] Furthermore, compared to the three-element capacitance sensor 100-5 (see Figures 33 and 34) having a detection electrode 102, a side ground electrode 104, and a first side shield electrode 103 on the upper surface 101A of the substrate 101, the capacitance sensor 100-8 of the fifth modified example does not have a current flowing through the detection object 20 (i.e., between the detection electrode 102 and the ground potential) that offsets the capacitance (Crg) between the detection electrode 102 and the detection object 20 due to the capacitance (Csg') between the first side shield electrode 103 and the detection object 20, thereby improving the detection accuracy of the detection object 20 by the detection electrode 102.

[0211] In addition, in the capacitance sensor 100-8 according to the fifth modified example, the amplitude of the second AC drive voltage V2 applied to the back shield electrode 106 from the second drive circuit 121B is made larger than the amplitude of the first AC drive voltage V1 applied to the detection electrode 102 from the first drive / detection circuit 121A.

[0212] As a result, in the capacitance-type sensor 100-8 according to the fifth modification, the parasitic capacitance Crgl (Crgl(a)+Crgl(b)) between the detection electrode 102 and the ground potential and between the detection electrode 102 and the side ground electrode 104 can be efficiently offset by the parasitic capacitance (Crs(a)) between the detection electrode 102 and the back shield electrode 106, and a detection signal with a high S / N ratio can be obtained by the detection electrode 102. Furthermore, saturation of the output voltage Vo of the operational amplifier 30 in FIG. 7 can be prevented, and the dynamic range of the output voltage Vo can be increased.

[0213] Furthermore, in the capacitance sensor 100-8 according to the fifth modified example, the distance D between the detection electrode 102 and the side ground electrode 104 is larger than the distance between the detection electrode 102 and the back shield electrode 106 (i.e., the thickness T1 of the substrate 101), and the opposing area between the detection electrode 102 and the side ground electrode 104 (i.e., the length L of the detection electrode 102 × the thickness T2 of the detection electrode 102) is smaller than the opposing area between the detection electrode 102 and the back shield electrode 106 (i.e., the length L of the detection electrode 102 × the width W of the detection electrode 102).

[0214] As a result, the capacitance type sensor 100-8 according to the fifth modified example can efficiently reduce the parasitic capacitance (Crgl(b)) between the detection electrode 102 and the side ground electrode 104 by using the parasitic capacitance (Crs(a)) between the detection electrode 102 and the back shield electrode 106, and therefore can increase the dynamic range of the output voltage Vo of the operational amplifier 30.

[0215] In addition, in the capacitance-type sensor 100-8 according to the fifth modification, the parasitic capacitance between the detection electrode 102 and the side ground electrode 104 is smaller than the parasitic capacitance between the detection electrode 102 and the back shield electrode 106.

[0216] As a result, the capacitance type sensor 100-8 according to the fifth modified example can efficiently reduce the parasitic capacitance (Crgl(b)) between the detection electrode 102 and the side ground electrode 104 by using the parasitic capacitance (Crs(a)) between the detection electrode 102 and the back shield electrode 106, and therefore can increase the dynamic range of the output voltage Vo of the operational amplifier 30 in FIG. 7.

[0217] <Fourth Experimental Example> Fig. 47 is a table showing the products used in the fourth experimental example. Fig. 48 is a table showing a list of the detection results of the fourth experimental example.

[0218] In the fourth experimental example, a change in capacitance (amount of change in detection signal strength) associated with a change in the display state of product J on the shelf 21 of the product shelf shown in Fig. 47 was detected using the two-element capacitance sensor 100-8 according to the fifth modified example and the three-element capacitance sensor 100-5 according to the second modified example. Specifically, the change in capacitance (amount of change in detection signal strength) was detected for each of the cases where product J on the first shelf was placed and removed, where product J on the second shelf was placed and removed, and where product J on the third shelf was placed and removed.

[0219] Product J: Packaged snacks (biscuits, laid flat, stacked three-tiered)

[0220] In the fourth experimental example, the two-element capacitance sensor 100-8 was configured so that one side ground electrode 104 was disposed between two detection electrodes 102 whose ends were electrically connected to each other. The three-element capacitance sensor 100-5 was configured so that two first side shield electrodes 103 whose ends were electrically connected to each other were disposed between two detection electrodes 102 whose ends were electrically connected to each other, and one side ground electrode 104 was disposed between the two first side shield electrodes 103.

[0221] As shown in Figure 48, in the fourth experimental example, the two-element capacitance sensor 100-8 was able to obtain a sufficient change in detection signal strength and a sufficient S / N ratio (20 dB or more) for each of the cases where product J was placed and removed from the first tier, where product J was placed and removed from the second tier, and where product J was placed and removed from the third tier.

[0222] On the other hand, as shown in Figure 48, in the fourth experimental example, the three-element capacitance sensor 100-5 was able to obtain a sufficient change in detection signal strength and a sufficient S / N ratio (20 dB or more) for each of the cases where product J was placed and removed from the first tier, where product J was placed and removed from the second tier, and where product J was placed and removed from the third tier.

[0223] In this way, in the fourth experimental example, both the two-element capacitance sensor 100-8 and the three-element capacitance sensor 100-5 have side ground electrodes 104, so changes in the display state of product J (changes in the detection signal strength) could be detected with high sensitivity.

[0224] However, as shown in Figure 48, in the fourth experimental example, when product J was placed and removed from the first tier and when product J was placed and removed from the second tier, the two-element capacitance sensor 100-8 was able to obtain a larger change in detection signal strength and a larger S / N ratio than the three-element capacitance sensor 100-5.

[0225] On the other hand, in the fourth experimental example, when product J on the third shelf was placed and removed, the three-element capacitance sensor 100-5 achieved a higher S / N ratio than the two-element capacitance sensor 100-8.

[0226] This is thought to be because the three-element capacitance sensor 100-5 has a first side shield electrode 103 between the detection electrode 102 and the side ground electrode 104, which increases the vertical density of electric field lines and results in higher vertical detection sensitivity, while the two-element capacitance sensor 100-8 does not have a first side shield electrode 103 between the detection electrode 102 and the side ground electrode 104, which increases the horizontal density of electric field lines and results in higher horizontal detection sensitivity.

[0227] Therefore, when emphasis is placed on detecting changes in the display status of products at relatively low positions, it is preferable to use the two-element capacitance sensor 100-8, and when emphasis is placed on detecting changes in the display status of products at relatively high positions, it is preferable to use the three-element capacitance sensor 100-5.

[0228] In addition, in the capacitance sensor 100-8 according to the fifth modified example, a background ground electrode 108 may be further provided on the lower surface 101B side of the substrate 101, spaced apart from and facing the back shield electrode 106, and connected to the side ground electrode 104.

[0229] As a result, the capacitance sensor 100-8 according to the fifth modification can effectively attenuate external electromagnetic noise from below (the negative direction of the Z axis). Furthermore, the capacitance sensor 100-8 according to the fifth modification can improve resistance to external noise, improve the stability of the potential of the side ground electrode 104, and prevent noise from entering the detection electrode 102, thereby improving the stability of the high S / N ratio of the detection signal.

[0230] Furthermore, in the capacitance sensor 100-8 according to the fifth modification, a second side shield electrode 105 may be further provided on the upper surface 101A of the substrate 101 in parallel with the detection electrode 102, the detection electrode 102 may be disposed between the side ground electrode 104 and the second side shield electrode 105, and a second AC drive voltage V2 may be applied to the second side shield electrode 105. This corresponds to the capacitance sensor 100-7 according to the fourth modification shown in FIG.

[0231] As a result, the capacitance sensor 100-8 according to the fifth modification can prevent external electromagnetic noise from flowing from the second side shield electrode 105 into the detection electrode 102, stabilize a high signal-to-noise ratio, and ensure high output.

[0232] In this case, the second drive circuit 121B of the detection circuit 120 may make the amplitude of the second AC drive voltage V2 applied to the back shield electrode 106 and the second side shield electrode 105 larger than the amplitude of the first AC drive voltage V1 applied to the detection electrode 102.

[0233] As a result, the capacitance sensor 100-8 according to the fifth variant can detect changes in the display state of the object to be detected 20 with high sensitivity and high SNR even under unfavorable conditions for electrostatic detection of the object to be detected 20 (for example, when the surface on which the object to be detected 20 is placed is separated from the detection electrode 102, when the conductivity or dielectric constant of the object to be detected 20 is low, etc.), and further, the dynamic range of the output voltage Vo of the operational amplifier 30 can be increased.

[0234] Furthermore, the sensor sheet 12 may be configured to include a plurality of capacitance type sensors 100-8 according to the fifth modified example, with the plurality of capacitance type sensors 100-8 arranged side by side and the plurality of capacitance type sensors 100-8 being integrally formed.

[0235] As a result, the sensor sheet 12 drives the multiple capacitance sensors 100-8 included in the sensor sheet 12, allowing each of the multiple capacitance sensors 100-8 included in the sensor sheet 12 to detect the detection object 20, and the detection results of the detection object 20 can be acquired collectively and efficiently from each of the multiple capacitance sensors 100-8 included in the sensor sheet 12. Furthermore, by forming the sensor sheet 12 in which the multiple capacitance sensors 100-8 are arranged side by side, the capacitance sensors 100-8 can be managed and formed collectively without having to be lined up individually.

[0236] In this case, the capacitance detection device 10 may be configured to include a sensor sheet 12 and a detection circuit 120 connected to each of the plurality of capacitance sensors 100-8 provided on the sensor sheet 12.

[0237] As a result, the capacitance detection device 10 can efficiently acquire the detection results of the detection object 20 from each of the multiple capacitance sensors 100-8 provided on the sensor sheet 12 in a batch by connecting each of the multiple capacitance sensors 100-8 provided on the sensor sheet 12 to a common detection circuit 120. Therefore, for example, by placing the sensor sheet 12 on a shelf board of a product shelf, the multiple capacitance sensors 100-8 provided on the sensor sheet 12 can efficiently detect the display status of products in each of multiple product rows (presence or absence of products, number of products, etc.) using a self-capacitance method.

[0238] Alternatively, in this case, the sensor unit 13 may have a plurality of sensor sheets 12 arranged side by side.

[0239] As a result, the sensor unit 13 drives the multiple capacitance sensors 100-8 in each of the multiple sensor sheets 12 included in the sensor unit 13, allowing each of the multiple capacitance sensors 100-8 to detect the detection target 20, and the detection results of the detection target 20 can be efficiently acquired collectively from each of the multiple capacitance sensors 100-8. Furthermore, the sensor unit 13 can easily adjust the number of capacitance sensors 100-8 by increasing or decreasing the number of sensor sheets 12.

[0240] Furthermore, in this case, the capacitance detection device 10 may be configured to include a sensor unit 13 and a detection circuit 120 connected to each of the plurality of capacitance sensors 100-8 included in the sensor unit 13.

[0241] As a result, the capacitance detection device 10 can efficiently acquire detection results of the detection target 20 collectively from each of the plurality of capacitance sensors 100-8 provided on each of the plurality of sensor sheets 12 by connecting each of the plurality of capacitance sensors 100-8 provided on each of the plurality of sensor sheets 12 to a common detection circuit 120. For this reason, for example, by placing the sensor unit 13 on a shelf board of a product shelf, each of the plurality of capacitance sensors 100-8 provided on each of the plurality of sensor sheets 12 can efficiently detect the display status of products in each of the plurality of product rows (presence or absence of products, number of products, etc.) using a self-capacitance method.

[0242] Although one embodiment of the present invention has been described in detail above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims.

[0243] This international application claims priority based on Japanese Patent Application No. 2023-138435, filed on August 28, 2023, the entire contents of which are incorporated herein by reference.

[0244] 10, 10-2, 10-3, 10-4, 10-5, 10-6, 10-7 Capacitance detection device 11 Circuit board 11A Lead wiring 12 Sensor sheet 13 Sensor unit 20 Object to be detected 21 Shelf board 21A Product row 100, 100-2, 100-3, 100-4, 100-5, 100-6, 100-7, 100-8, 100-9 Capacitance sensor 100A Connection portion 101 Base material 101A Upper surface 101B Lower surface 102 Detection electrode 102A Straight portion 102B Connection portion 103 First side shield electrode 103A Straight portion 103B Connection portion 104 Side ground electrode 105 Second side shield electrode 106 Back shield electrode 107 Cover 108 Background electrode 120, 120-2, 120-3 Detection circuit 121 Capacitance detection unit 121A First drive / detection circuit 121B Second drive circuit 122 Processing unit 124 I / F Ds Detection signal V1 First AC drive voltage V2 Second AC drive voltage 910 Conventional capacitance sensor 911 Substrate 911A Upper surface 911B Lower surface 912 Detection electrode 913 Side shield electrode 913A Straight portion 913B Connection portion 916 Back shield electrode 917 Cover 918 Background electrode 920 Detection circuit

Claims

1. A capacitance type sensor comprising: a substrate; a detection electrode arranged on one surface of the substrate; a first side shield electrode arranged in parallel with the detection electrode on the one surface of the substrate; and a back shield electrode arranged facing the detection electrode via the substrate on the other surface of the substrate, wherein a first AC drive voltage is applied to the detection electrode, and a second AC drive voltage having the same frequency and phase as the first AC drive voltage is applied to the first side shield electrode and the back shield electrode, and further comprising a side ground electrode arranged in parallel with the detection electrode and the first side shield electrode on the one surface of the substrate and connected to a ground potential.

2. The capacitance type sensor according to claim 1, characterized in that the first side shield electrode is disposed between the detection electrode and the side ground electrode.

3. The capacitance type sensor according to claim 1 or 2, further comprising a second side shield electrode arranged in parallel with the detection electrode on said one surface of the base material, the detection electrode being disposed between the first side shield electrode and the second side shield electrode, and the second AC drive voltage being applied to the second side shield electrode.

4. The capacitance type sensor according to claim 3, characterized in that the second side shield electrode is formed integrally with the back shield electrode and covers a side surface of the area between the detection electrode and the back shield electrode.

5. The capacitance type sensor as described in claim 1 or 2, characterized in that the detection electrode, the side ground electrode, and the first side shield electrode have a longitudinal direction in a first direction, and further include a connection portion with an extraction wiring provided at one end in the first direction, the first side shield electrode has two straight portions arranged in parallel with the side ground electrode and a connection portion connecting the other ends of the two straight portions in the first direction, and the detection electrode has two straight portions arranged in parallel with the side ground electrode and a connection portion connecting the other ends of the two straight portions in the first direction.

6. The capacitance type sensor described in claim 3, characterized in that the detection electrode, the side ground electrode, the first side shield electrode, and the second side shield electrode have a longitudinal direction in a first direction, and further include a connection portion with an extraction wiring provided at one end in the first direction, and the second side shield electrode has two straight portions arranged in parallel with the side ground electrode and a connection portion connecting the other ends in the first direction of the two straight portions.

7. The capacitance type sensor according to claim 1 or 2, further comprising a background electrode provided on the other surface side of the substrate, spaced apart from and facing the back shield electrode, and connected to the side ground electrode.

8. A sensor sheet comprising a plurality of the capacitance type sensors according to claim 1, the plurality of capacitance type sensors being arranged in parallel and integrally formed.

9. A sensor unit comprising a plurality of the sensor sheets according to claim 8, the plurality of sensor sheets being arranged in parallel.

10. A detection circuit for a capacitance type sensor as described in claim 1, comprising: a first drive / detection circuit that applies the first AC drive voltage to the detection electrode and detects a change in current flowing through the detection electrode; and a second drive circuit that applies the second AC drive voltage to the first side shield electrode and the back shield electrode, wherein the amplitude of the second AC drive voltage is greater than the amplitude of the first AC drive voltage.

11. A detection circuit for a capacitance type sensor as described in claim 3, comprising: a first drive / detection circuit that applies the first AC drive voltage to the detection electrode and detects a change in current flowing through the detection electrode; and a second drive circuit that applies the second AC drive voltage to the first side shield electrode, the second side shield electrode, and the back shield electrode, wherein the amplitude of the second AC drive voltage is greater than the amplitude of the first AC drive voltage.

12. A capacitance detection device comprising: the sensor sheet according to claim 8; and a detection circuit connected to each of a plurality of capacitance sensors provided on the sensor sheet.

13. A capacitance detection device comprising: a sensor unit according to claim 9; and a detection circuit connected to each of a plurality of capacitance sensors included in the sensor unit.

14. A capacitance type sensor comprising: a substrate; a detection electrode arranged on one surface of the substrate; and a back shield electrode arranged on the other surface of the substrate facing the detection electrode via the substrate, wherein a first AC drive voltage is applied to the detection electrode, and a second AC drive voltage having the same frequency and phase as the first AC drive voltage and a larger amplitude than the first AC drive voltage is applied to the back shield electrode, and further comprising a side ground electrode disposed in parallel with the detection electrode on the one surface of the substrate and connected to a ground potential.

15. The capacitance type sensor according to claim 14, characterized in that the distance between the detection electrode and the side ground electrode is larger than the distance between the detection electrode and the back shield electrode, and the opposing area between the detection electrode and the side ground electrode is smaller than the opposing area between the detection electrode and the back shield electrode.

16. The capacitive sensor according to claim 14, wherein the parasitic capacitance between the detection electrode and the side ground electrode is smaller than the parasitic capacitance between the detection electrode and the back shield electrode.

17. The capacitance type sensor as described in claim 14, further comprising a second side shield electrode arranged in parallel with the detection electrode on the one surface of the substrate, the detection electrode being disposed between the side ground electrode and the second side shield electrode, and the second AC drive voltage being applied to the second side shield electrode.

18. The capacitance type sensor according to claim 14, further comprising a background electrode provided on the other surface side of the substrate, spaced apart from and facing the back shield electrode, and connected to the side ground electrode.

19. A sensor sheet comprising a plurality of the capacitance type sensors according to claim 14, the plurality of capacitance type sensors being arranged in parallel and integrally formed.

20. A sensor unit comprising a plurality of sensor sheets according to claim 19, the plurality of sensor sheets being arranged in parallel.

21. A detection circuit for a capacitance type sensor as described in claim 14, comprising: a first drive / detection circuit that applies the first AC drive voltage to the detection electrode and detects a change in current flowing through the detection electrode; and a second drive circuit that applies the second AC drive voltage to the back shield electrode, wherein the amplitude of the second AC drive voltage is greater than the amplitude of the first AC drive voltage.

22. A detection circuit for a capacitance type sensor as described in claim 17, comprising: a first drive / detection circuit that applies the first AC drive voltage to the detection electrode and detects a change in current flowing through the detection electrode; and a second drive circuit that applies the second AC drive voltage to the back shield electrode and the second side shield electrode, wherein the amplitude of the second AC drive voltage is greater than the amplitude of the first AC drive voltage.

23. The detection circuit according to claim 21 or 22, characterized in that: the first drive / detection circuit is electrically connected to the detection electrode via an outgoing wiring; the first drive / detection circuit has a first AC voltage circuit which is an operational amplifier, a feedback resistor, a feedback capacitor, and a first AC power source; the first AC voltage circuit generates the first AC drive voltage and applies the first AC drive voltage to a non-inverting input terminal of the operational amplifier; the detection electrode is connected to the inverting input terminal of the operational amplifier via the outgoing wiring; the operational amplifier amplifies the voltage difference between the inverting input terminal connected to the detection electrode and the non-inverting input terminal to which the first AC drive voltage is applied, and outputs an output voltage; and the feedback resistor and the feedback capacitor are connected in parallel between the output terminal and the inverting input terminal of the operational amplifier, thereby applying negative feedback.

24. A capacitance detection device comprising: a sensor sheet according to claim 19; and a detection circuit connected to each of a plurality of capacitance sensors provided on the sensor sheet.

25. A capacitance detection device comprising: a sensor unit according to claim 20; and a detection circuit connected to each of a plurality of capacitance sensors included in the sensor unit.

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