Electrostatic capacitance sensor

Abstract

Provided is an electrostatic capacity sensor capable of correctly detecting pressing of an object. The electrostatic capacity sensor includes: one or more surface-side electrodes including a detection electrode; a cover disposed on the surface side of the one or more surface-side electrodes; an elastic dielectric disposed on the back side of the one or more surface-side electrodes; a shield electrode disposed on the back side of the elastic dielectric; a first voltage output portion that outputs a first alternating voltage to a drive portion coupled to the detection electrode via a capacity; a second voltage output portion that outputs a second alternating voltage of the same phase as the first alternating voltage to the shield electrode; a detection portion connected to the detection electrode, which detects an output corresponding to the capacity of the one or more surface-side electrodes; and a motion determination portion that determines a motion of the object based on the output of the detection portion. The second voltage output portion is capable of changing the amplitude of the second alternating voltage, and the motion determination portion determines that a pressing motion of the object toward the cover is performed based on a plurality of outputs of the detection portion obtained when the second voltage output portion changes the amplitude of the second alternating voltage to a plurality of amplitudes, respectively.

Description

Technical Field

[0001] This invention relates to electrostatic capacitive sensors. Background Technology

[0002] A display device now exists having: a light-emitting element layer; a plurality of first electrodes extending in a first direction and adjacent to each other in a second direction intersecting the first direction; a plurality of second electrodes extending in the second direction and adjacent to each other in the first direction above the plurality of first electrodes; an insulating elastic layer between the plurality of first electrodes and the plurality of second electrodes for ensuring spacing; and a sensing circuit.

[0003] The sensing circuit measures a first physical quantity corresponding to a first electrostatic capacitance parasitized in each of the plurality of first electrodes and the plurality of second electrodes. When the obtained first measured value deviates from a first range, it senses an intentional change in the first electrostatic capacitance caused by the approach of a conductive body including a finger. The sensing circuit also measures a second physical quantity corresponding to a second electrostatic capacitance between each of the plurality of first electrodes and each of the plurality of second electrodes. When the obtained second measured value deviates from a second range, it senses an intentional change in the second electrostatic capacitance caused by the compression of the insulating elastic layer due to pressure (for example, see Patent Document 1).

[0004] Prior art literature

[0005] Patent documents

[0006] Patent Document 1: US Patent No. 10,429,984B2 Specification Summary of the Invention

[0007] -The problem the invention aims to solve-

[0008] However, existing display devices cannot accurately measure the pressure applied because both the first and second electrostatic capacitive capacitors are affected by the proximity and pressure of the finger.

[0009] Therefore, the objective is to provide a capacitive sensor that can accurately detect pressure applied by the object being detected.

[0010] -Solution methods-

[0011] An electrostatic capacitive sensor according to an embodiment of the present invention includes: one or more surface electrodes, including one or more detection electrodes; a cover disposed on the surface of the one or more surface electrodes; an elastic dielectric disposed on the back side of the one or more surface electrodes; a shielding electrode disposed on the back side of the elastic dielectric; a first voltage output unit that outputs a first AC voltage to a drive unit coupled to the one or more detection electrodes via a capacitor; a second voltage output unit that outputs a second AC voltage with the same phase as the first AC voltage to the shielding electrode; a detection unit connected to the one or more detection electrodes and detecting the output corresponding to the capacitance of the one or more surface electrodes; and an action determination unit that determines the action of a detected object based on the output of the detection unit, wherein the second voltage output unit is capable of changing the amplitude of the second AC voltage, and the action determination unit determines that the pressed action of the detected object onto the cover has occurred based on the multiple outputs of the detection unit obtained when the second voltage output unit changes the amplitude of the second AC voltage to multiple amplitudes respectively.

[0012] -Invention Effects-

[0013] It can provide a capacitive sensor that can accurately detect pressure applied by the object being detected. Attached Figure Description

[0014] Figure 1 This is a diagram showing the planar structure of the electrostatic capacitive sensor 100 according to Embodiment 1.

[0015] Figure 2 This is a diagram showing a cross-sectional structure of a portion of the electrostatic capacitive sensor 100.

[0016] Figure 3 This is a diagram showing the equivalent circuit of the electrostatic capacitive sensor 100.

[0017] Figure 4 It represents AC voltage V A AC voltage V B AC voltage V C A diagram of an example waveform.

[0018] Figure 5 This is a graph showing the time-varying capacitances Cf and Cs in the electrostatic capacitive sensor 100 and the output voltage V0.

[0019] Figure 6 This is a diagram showing the electrostatic capacitive sensor 200 according to Embodiment 2.

[0020] Figure 7 This is a diagram showing the electrostatic capacitive sensor 300 of Embodiment 3. Detailed Implementation

[0021] Hereinafter, embodiments of the electrostatic capacitive sensor to which the present invention is applied will be described.

[0022] <Implementation Method 1>

[0023] Figure 1 This is a diagram showing the planar structure of the electrostatic capacitive sensor 100 according to Embodiment 1. Hereinafter, an XYZ coordinate system will be defined for explanation. The direction parallel to the X-axis (X direction), the direction parallel to the Y-axis (Y direction), and the direction parallel to the Z-axis (Z direction) are orthogonal to each other. Furthermore, for ease of explanation, the -Z direction side will sometimes be referred to as the lower side or "down," and the +Z direction side as the upper side or "up," but this does not represent a universal vertical relationship. Additionally, the upper surface side of a structural element is called the "front side," and the lower surface side is called the "back side." Also, "top view" refers to observation from the XY plane. Furthermore, the length, thickness, and other dimensions of each part will sometimes be exaggerated below to facilitate understanding of the structure.

[0024] The capacitive sensor 100 includes a cover 101 and a plurality of surface electrodes 110. The cover 101 is disposed on the surface of the plurality of surface electrodes 110. The capacitive sensor 100 also includes an action determination unit that determines whether a user's action involves approaching, touching, or pressing the cover 101, such as with a fingertip. Figure 1 The diagram is omitted, showing the planar structure of the cover 101 and the plurality of surface electrodes 110.

[0025] As an example, cover 101 is a transparent glass or resin plate-like member that can flex when pressed from the top surface, appearing rectangular from above. The top surface is the operating surface where the user makes input by touching it with their fingertips or similar objects. The user can also press the top surface of cover 101 downwards. Cover 101 is configured as a top plate covering the top surface of the electrostatic capacitive sensor 100.

[0026] Multiple surface electrodes 110 are disposed on the lower surface of the cover 101 and arranged in a matrix in the X and Y directions. As an example, the multiple surface electrodes 110 are independent of each other and are connected to the detection unit, etc., described later, via wiring (not shown) that is wound around each other in a top view.

[0027] exist Figure 1The plurality of surface-side electrodes 110 are shown in perspective. These electrodes 110 are, for example, transparent electrodes made of ITO (Indium Tin Oxide). Furthermore, this description assumes a display panel such as a liquid crystal or organic EL (Electroluminescence) sensor is disposed below the capacitive sensor 100, and that the cover 101 and the plurality of surface-side electrodes 110 are transparent. However, in cases where no display panel is disposed, the cover 101 and the plurality of surface-side electrodes 110 may be opaque, as long as they are made of a conductive material. In this case, the plurality of surface-side electrodes 110 may also be metal plates or the like.

[0028] Figure 2 This is a diagram showing a cross-sectional structure of a portion of the electrostatic capacitive sensor 100. Figure 2 The diagram shows the cross-sectional structure of the portion containing three surface electrodes 110 arranged in the X direction. Here, as an example, we will explain how a user operates the capacitive sensor 100 by touching (contacting) the cover 101 with their fingertip FT. The fingertip FT is an example of a detected object. The user operates the sensor by touching (contacting) the cover 101 with their fingertip FT.

[0029] The electrostatic capacitive sensor 100, in addition to the cover 101 and the surface electrode 110, includes an elastic dielectric 120, a shielding electrode 130, an amplifier circuit 140A, an amplifier circuit 140B, a variable amplifier circuit 140C, a power supply circuit 145, a detection unit 150, selection units 160A and 160B, and a control device 170. The power supply circuit 145 is an AC voltage source that outputs a sinusoidal AC voltage of a given amplitude, supplying AC voltage to the amplifier circuits 140A, 140B, and 140C. The amplifier circuit 140A and power supply circuit 145 are an example of a first voltage output unit, the amplifier circuit 140B and power supply circuit 145 are an example of a third voltage output unit, and the variable amplifier circuit 140C and power supply circuit 145 are an example of a second voltage output unit. The control device 170 includes an operation determination unit 171 and a holding unit 172. Furthermore, the electrostatic capacitive sensor 100 also includes a substrate 102.

[0030] As an example, selection unit 160A selects two of the plurality of surface-side electrodes 110 as the connection destination of amplifier circuit 140A. Alternatively, as an example, selection unit 160B selects one of the plurality of surface-side electrodes 110 as the connection destination of amplifier circuit 140B and detection unit 150. Here, selection unit 160B selects as follows: Figure 2 The central surface-side electrode 110 of the three surface-side electrodes 110 shown is connected to the amplifier circuit 140B and the detection unit 150. Additionally, the selection unit 160A selects... Figure 2 Two of the three surface-side electrodes 110 shown are connected to the amplifier circuit 140A at both ends.

[0031] exist Figure 2 Of the three surface-side electrodes 110 shown, the central surface-side electrode 110 is the detection electrode 111, and the two surface-side electrodes 110 located on either side of the detection electrode 111 are driving electrodes 112. The driving electrode 112 is an example of a driving unit. Therefore, the reference numeral 110 is denoteed in parentheses in the reference numerals 110 for the detection electrode 111 and the driving electrode 112.

[0032] The detection electrode 111 is one of the plurality of surface-side electrodes 110, selected by the selection unit 160B and connected to the amplifier circuit 140B and the detection unit 150. The drive electrode 112 is one of the plurality of surface-side electrodes 110, selected by the selection unit 160A and connected to the amplifier circuit 140A. Furthermore, the following description of the surface-side electrode 110 does not specifically distinguish between the detection electrode 111 and the drive electrode 112, and will describe surface-side electrodes 110 other than the detection electrode 111 and the drive electrode 112.

[0033] The detection electrode 111 is used to detect when the user's fingertip FT approaches, touches, or presses the cover 101. The electrostatic capacitance sensor 100 detects the approach, contact, and press of the fingertip FT by sequentially selecting multiple surface-side electrodes 110 as detection electrodes 111 and detecting electrostatic capacitance through the selection unit 160B. At this time, the AC voltage V output from the power supply circuit 145 and amplified by the amplifier circuit 140B... B An AC voltage V is applied to the detection electrode 111 via the detection unit 150. B This is an example of the third AC voltage. When the action determination unit 171 determines that the detection electrode 111 selected by the selection unit 160B has been touched or pressed, an operation input is performed at the position (coordinate) corresponding to the detection electrode 111.

[0034] Here, the method of selecting multiple face-side electrodes 110 one by one as detection electrodes 111 has been described. However, the selection unit 160B may also simultaneously select two or more face-side electrodes 110 that are not adjacent to each other as detection electrodes 111, and simultaneously detect the approach, contact, and pressing of the fingertip FT with two or more detection electrodes 111. Therefore, the multiple face-side electrodes 110 include one or more detection electrodes 111.

[0035] The driving electrode 112 is the surface electrode 110 located on the left and right sides of the detection electrode 111 in the X direction. When the electrostatic capacitance sensor 100 selects the multiple surface electrodes 110 one by one as the detection electrode 111 through the selection unit 160B, the selection unit 160A selects the two surface electrodes 110 located on the left and right sides of the detection electrode 111 in the X direction as the two driving electrodes 112.

[0036] When the proximity, contact, and pressing of the fingertip FT are detected by the detection electrode 111, the AC voltage V output from the power supply circuit 145 and amplified by the amplifier circuit 140A is... A An AC voltage V is applied to the driving electrode 112. A This is an example of the first AC voltage, with amplitude V. A (V) AC voltage. Furthermore, here, the method of setting the two surface-side electrodes 110 located on the left and right sides of the detection electrode 111 in the X direction as driving electrodes 112 has been described, but it is also possible to set a total of four surface-side electrodes 110, namely the two surface-side electrodes 110 located on the left and right sides of the detection electrode 111 in the X direction and the two surface-side electrodes 110 located on the left and right sides of the detection electrode 111 in the Y direction, as driving electrodes 112.

[0037] Furthermore, for example, when the surface electrode 110 located at the end in the X direction is used as the detection electrode 111, the two surface electrodes 110 on the left and right sides of the detection electrode 111 in the Y direction can be used as two driving electrodes 112. Alternatively, the surface electrode 110 adjacent to the detection electrode 111 in the +X direction and the surface electrode 110 adjacent to the detection electrode 111 in the -Y or +Y direction can be used as two driving electrodes 112. Additionally, when the surface electrode 110 located at the corner of a plurality of surface electrodes 110 arranged in a matrix is ​​used as the detection electrode 111, the surface electrode 110 adjacent to the detection electrode 111 in the X direction and the surface electrode 110 adjacent to the detection electrode 111 in the Y direction can be used as two driving electrodes 112.

[0038] The elastic dielectric 120 is disposed on a plurality of surface electrodes 110 (see reference). Figure 1 as well as Figure 2 The back (bottom) of the cover 101. The elastic dielectric 120 is a transparent and elastically deformable dielectric, such as containing polyurethane resin. The elastic dielectric 120 is positioned to overlap all of the plurality of surface electrodes 110 when viewed from above, and its thickness in the Z direction is uniform. Because the elastic dielectric 120 is elastically deformable, if the user presses the portion directly above the detection electrode 111 on the upper surface of the cover 101 with their fingertip ET, the elastic dielectric 120 flexes and contracts, thereby slightly displacing the detection electrode 111 downward.

[0039] The shielding electrode 130, while being disposed on the upper surface of the substrate 102, is positioned below the elastic dielectric 120. That is, the shielding electrode 130, with the elastic dielectric 120 sandwiched between it and the plurality of surface electrodes 110, is disposed on the back side of the plurality of surface electrodes 110. The shielding electrode 130 is configured to shield the plurality of surface electrodes 110 from noise and to suppress parasitic capacitance with ground, and is applied with an AC voltage V output from the power supply circuit 145 and amplified by the variable amplifier circuit 140C. C1 or V C2 AC voltage V C1 and V C2 These are all examples of a second AC voltage, and are examples of a second AC voltage with multiple amplitudes. As an example, the shielding electrode 130 contains a transparent conductive material such as an ITO film. Furthermore, the substrate 102 is a transparent substrate that holds the shielding electrode 130. For example, if a display panel is not disposed below, both the shielding electrode 130 and the substrate 102 holding the shielding electrode 130 may be opaque.

[0040] Amplifier circuit 140A amplifies the AC voltage output from power supply circuit 145 to AC voltage V. A And output to the drive electrode 112. As an example, the amplifier circuit 140A is configured to selectively connect to all of the plurality of surface-side electrodes 110 via the selection unit 160A. The selection unit 160A connects to the two surface-side electrodes 110 selected as drive electrodes 112 by switching the wiring connection between all of the plurality of surface-side electrodes 110, and outputs an AC voltage V. A Furthermore, since two or more non-adjacent surface electrodes 110 can be simultaneously selected as detection electrodes 111 to simultaneously detect the approach, contact, and press of the fingertip FT, the amplifier circuit 140A outputs an AC voltage V to the drive electrode 112, which is capacitively coupled between one or more detection electrodes 111. A .

[0041] Amplifier circuit 140B is connected to the positive input terminal (+) of operational amplifier 152 in detection unit 150, and amplifies the AC voltage output from power supply circuit 145 to AC voltage V. B And output. Operational amplifier 152 is an example of an operational amplifier. AC voltage V B The amplitude is V B The AC voltage is the AC voltage V. A The following (V) A ≥V B The voltage of ). Additionally, the AC voltage V B Frequency and AC voltage V A The frequencies are equal, and the phase is also the same as the AC voltage V. AEqual (in the same phase). The amplifier circuit 140B outputs an AC voltage V to the surface electrode 110, selected as the detection electrode 111 by the selection unit 160B, via the detection unit 150. B This will be discussed in more detail later.

[0042] The variable amplifier circuit 140C is connected to the shielding electrode 130 and amplifies the AC voltage output from the power supply circuit 145 to an AC voltage V. C1 Or V C2 And output. AC voltage V C1 and V C2 The amplitudes are V C1 and V C2 The AC voltage. The variable amplifier circuit 140C, by controlling the amplification rate via the control device 170, can change the amplitude of the second AC voltage into multiple amplitudes, here set to amplify the AC voltage output from the power supply circuit 145 to AC voltage V. C1 Or V c2 (V C1 >V C2 And output. AC voltage V C1 and V C2 Amplitude V C1 and V C2 Less than AC voltage V B Amplitude V B (V B >V C1 >V C2 ), and has AC voltage V A and AC voltage V B Equal frequency. This is configured as a variable amplifier circuit 140C, capable of changing the amplitude of the AC voltage to V. C1 Or V C2 This is to detect the capacitance (static capacitance) Cs between the detection electrode 111 and the shielding electrode 130 using AC voltages of two amplitudes. Details will be discussed later.

[0043] Power supply circuit 145 outputs an AC voltage of a given frequency. Amplifier circuits 140A and 140B, and a variable amplifier circuit 140C are connected to the output side of power supply circuit 145. The AC voltage of the given frequency output by power supply circuit 145 is amplified by amplifier circuits 140A, 140B, and 140C. Therefore, the AC voltage V output by amplifier circuits 140A, 140B, and 140C is... A V B V C1 and V C2 They have the same frequency and the same phase.

[0044] The detection unit 150 includes an input terminal 151, an operational amplifier 152, a capacitor 153, a resistor 154, and an output terminal 155. The detection unit 150 uses detection electrodes 111 to detect the proximity, contact, and pressing of the user's fingertip FT.

[0045] As an example, input terminal 151 is configured to selectively connect to all of the plurality of surface-side electrodes 110 via selection unit 160B, and connect to detection electrode 111 selected by selection unit 160B by switching the wiring via selection unit 160B. Input terminal 151 outputs AC voltage V to detection electrode 111 selected by selection unit 160B. B .

[0046] Operational amplifier 152 has: an inverting input terminal (-), connected to a detection electrode 111 selected by selection unit 160B via input terminal 151 of detection unit 150; and a non-inverting input terminal (+), connected to amplifier circuit 140B, with AC voltage V. B The input and output terminals are connected to the output terminal 155. Since the operational amplifier 152 performs negative feedback operation through the capacitor 153 and resistor 154 as feedback elements, it amplifies the voltage difference between the inverting input terminal (-) and the non-inverting input terminal (+) to zero. Therefore, through the virtual short circuit of the operational amplifier 152, which is a non-inverting amplifier circuit, the voltage at the inverting input terminal (-) becomes equal to the voltage applied to the non-inverting input terminal (+). Thus, the AC voltage V... B Apply to detection electrode 111.

[0047] Capacitor 153 is connected between the inverting input terminal (-) and the output terminal of operational amplifier 152. The capacitance (static capacitance) of capacitor 153 is Cq. Resistor 154 is connected in parallel with capacitor 153. The resistance of resistor 154 is Rq.

[0048] Output terminal 155 is connected to the output terminal of operational amplifier 152 and to control device 170. The output voltage of output terminal 155 is V0. Since operational amplifier 152 performs negative feedback operation through capacitor 153 and resistor 154 as feedback elements, the voltage at the inverting input terminal (-) becomes equal to the voltage applied to the non-inverting input terminal (+) through a virtual short circuit. Therefore, an AC voltage V is output to input terminal 151. B An alternating voltage V is applied to the detection electrode 111 via the selection unit 160B. B .

[0049] The selection unit 160A has: an input terminal connected to the amplifier circuit 140A; and multiple output terminals connected to all of the multiple surface-side electrodes 110. Based on a command input from the control device 170, the selection unit 160A switches the connection destination of the input terminal to two output terminals connected to two of the multiple surface-side electrodes 110. In this way, the selection unit 160A selects two surface-side electrodes 110 as drive electrodes 112. The selection unit 160A receives the AC voltage V input from the amplifier circuit 140A. A Output is provided to the two drive electrodes 112. For example, a selector can be used as such a selection unit 160A.

[0050] The selection unit 160B has: an input terminal connected to the input terminal 151 of the detection unit 150; and multiple output terminals connected to all of the multiple surface-side electrodes 110. Based on a command input from the control device 170, the selection unit 160B switches the connection destination of the input terminal to one output terminal connected to one of the multiple surface-side electrodes 110. In this way, the selection unit 160B selects one surface-side electrode 110 as the detection electrode 111. The selection unit 160B selects the AC voltage V input from the amplifier circuit 140B via the detection unit 150. B Output is sent to the detection electrode 111. As such a selection unit 160B, a selector can be used, for example.

[0051] The control device 170 is implemented using a computer that includes a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), input / output interfaces, and an internal bus. The control device 170 has an action determination unit 171 and a holding unit 172. In addition to the action determination unit 171 and the holding unit 172, the control device 170 also has a variable amplifier circuit 140C that adjusts the amplification rate (to AC voltage V). C1 Or V C2 The processing units, such as switching of magnification, switching of selection units 160A and 160B, etc., are omitted here. The action determination unit 171 displays one function of the control device 170 as a block, and the holding unit 172 displays the RAM functions of the control device 170.

[0052] The motion determination unit 171 detects the proximity, contact, and pressing of the fingertip FT based on the output voltage V0 of the output terminal 155 of the detection unit 150. The specific detection method will be described later.

[0053] When the action determination unit 171 detects the approach, contact, or pressing of the fingertip FT based on the output voltage V0, the holding unit 172 temporarily holds the data representing the output voltage V0. This will be described in detail later.

[0054] Here, multiple surface electrodes 110 are arranged at equal intervals in the X and Y directions, and there is a capacitance (static capacitance) between adjacent surface electrodes 110. That is, the detection electrode 111 and the driving electrode 112 are capacitively coupled. In other words, the driving electrode 112 is capacitively coupled to the detection electrode 111. Here, the capacitance between the detection electrode 111 and the driving electrode 112 on the -X direction side is set as Cp1, and the capacitance between the detection electrode 111 and the driving electrode 112 on the +X direction side is set as Cp2. Capacitances Cp1 and Cp2 are constant values.

[0055] Furthermore, the capacitance (electrostatic capacitance) generated between the detection electrode 111 and the fingertip FT is defined as Cf. The closer the fingertip FT is to the detection electrode 111, the larger the capacitance Cf becomes. Since there is a cover 101 between the detection electrode 111 and the fingertip FT, if the fingertip FT approaches the detection electrode 111, the capacitance Cf increases until the fingertip FT contacts the detection electrode 111 directly above the upper surface of the cover 101. In addition, if a pressing operation is performed where the fingertip FT presses down on the cover 101, the fingertip FT deforms, and the contact area with the cover 101 increases, thereby increasing the capacitance Cf further according to the increase in pressing force.

[0056] Furthermore, the capacitance (static capacitance) between the detection electrode 111 and the shielding electrode 130 is set as Cs. If the user presses the portion directly above the detection electrode 111 on the upper surface of the cover 101 with their fingertip FT, the elastic dielectric 120 flexes and contracts, thereby shortening the distance d between the detection electrode 111 and the shielding electrode 130. Therefore, when a pressing operation is performed, the capacitance Cs increases corresponding to the distance d between the detection electrode 111 and the shielding electrode 130.

[0057] Thus, if a pressing operation is performed by pressing the cover 101 downwards with the fingertip FT, both capacitance Cf and capacitance Cs will increase. If both capacitance Cf and capacitance Cs increase, it may become difficult to determine that a pressing operation has occurred. Therefore, in the electrostatic capacitance sensor 100, in order for the action determination unit 171 to determine that a pressing operation has occurred, the amplitude of the AC voltage output by the variable amplifier circuit 140C is set to V by a time difference. C1 and V C2 .

[0058] The AC voltage V output by the variable amplifier circuit 140C C1 Or V C2Applied to shielding electrode 130. Capacitance Cf is the electrostatic capacitance between detection electrode 111 and fingertip FT, due to capacitance C s It is the electrostatic capacitance between the detection electrode 111 and the shielding electrode 130, therefore the AC voltage V output by the variable amplifier circuit 140C is... C1 V C2 Change (V) C1 -V C2 It affects capacitor Cs, but has no effect on capacitor Cf.

[0059] Therefore, in order to determine whether a pressing operation has occurred by using the detection electrode 111 selected by the selection unit 160B, the electrostatic capacitance sensor 100 causes the variable amplifier circuit 140C to output an amplitude V. C1 After applying the AC voltage, the amplitude is changed to V. C2 and apply amplitude V C2 The AC voltage. In fact, all of the multiple surface-side electrodes 110 arranged in a matrix are sequentially selected by the selection unit 160B to become detection electrodes 111. This selection operation is repeated, thereby repeatedly selecting all the surface-side electrodes 110 as detection electrodes 111 multiple times. Simultaneously, the position of the fingertip FT and whether a pressing operation has occurred are determined for each detection electrode 111. Therefore, whenever one surface-side electrode 110 is selected as a detection electrode 111 by the selection unit 160B, the variable amplifier circuit 140C outputs an amplitude V... C1 After the AC voltage, the output amplitude V C2 The AC voltage. This is to detect the amplitude V applied to the shielding electrode 130 at almost the same position as the fingertip FT. C1 The capacitance Cs under AC voltage and the applied amplitude V C2 The capacitance Cs when the AC voltage is applied.

[0060] In addition, the motion determination unit 171 determines the approach and contact of the fingertip FT and outputs an AC voltage V in the variable amplifier circuit 140C. C1 Or V C2 Either is acceptable. Here, as an example, the action determination unit 171 outputs an AC voltage V based on the variable amplifier circuit 140C. C1 The capacitance Cf at that time is used to determine the proximity and contact of the fingertip FT. In addition, the variable amplifier circuit 140C outputs an amplitude V to each detection electrode 111. C2 AC voltage and amplitude V C1 The order of the AC voltages is not limited to the order described above. The variable amplifier circuit 140C can also, when each of the meter-side electrodes 110 is selected as the detection electrode 111, output amplitude V... C2 After the AC voltage, the output amplitude V C1 AC voltage.

[0061] Here, the amplitude of the AC voltage output by the variable amplifier circuit 140C is set to V. C1 and V C2 When the action determination unit 171 detects a pressing operation, it uses the output voltage V0 of the output terminal 155. Therefore, before explaining the method by which the action determination unit 171 determines whether a pressing operation has occurred, here, we will use... Figure 3 as well as Figure 4 The method for calculating the output voltage V0 is the same as that for calculating the AC voltage V. A AC voltage V B AC voltage V C The relationship between the amplitude and the amplitude is explained.

[0062] Figure 3 This is a diagram showing the equivalent circuit of the electrostatic capacitive sensor 100. In Figure 3 In the diagram, the equivalent circuit of the portion of the capacitive sensor 100 excluding the control device 170 is represented. Since the capacitance Cf varies with the distance between the fingertip FT and the detection electrode 111, and the contact area of ​​the fingertip FT, it is represented as a variable capacitance. Similarly, since the capacitance Cs varies with the distance d between the detection electrode 111 and the shielding electrode 130 based on the pressing operation, it is also represented as a variable capacitance. Furthermore, hereinafter, without distinguishing between AC voltage V... C1 and V C2 In this case, it is called AC voltage V C Because of V B >V C1 >V C2 Therefore V B >V C .

[0063] In the electrostatic capacitive sensor 100 with such a structure, the following equation (1) holds. Equation (1) is a formula that holds true between the detection electrode 111, the driving electrode 112, and the shielding electrode 130 through the law of conservation of charge. The voltage integrated in the capacitor 153 with capacitance Cq represents the output voltage V0. Furthermore, capacitance Cp = Cp1 + Cp2. When using four driving electrodes 112, capacitance Cp is the sum of the four capacitances generated between the detection electrode 111 and the four driving electrodes 112.

[0064] [Mathematical Expression 1]

[0065] Cf×V B +(V B -V A )×Cp+(V B -V C )×Cs=Cq×V O (1)

[0066] If equation (1) is modified, the output voltage V0 of output terminal 155 is represented by equation (2).

[0067] [Mathematical Expression 2]

[0068]

[0069] Furthermore, the capacitance Cs between the detection electrode 111 and the shielding electrode 130 is represented by the following formula (3). In addition, ε0 is the dielectric constant in vacuum, εr is the relative dielectric constant of the elastic dielectric 120, s is the area of ​​the detection electrode 111, and d is the distance (gap) between the detection electrode 111 and the shielding electrode 130. If the distance d decreases, the capacitance Cs increases.

[0070] [Mathematical Expression 3]

[0071]

[0072] Here, as an example, since the action determination unit 171 outputs an AC voltage V based on the variable amplifier circuit 140C... C1 The capacitance Cf at that time is used to determine the proximity and contact of the fingertip FT, therefore V C1 Substituting V into equation (2) C The output voltage V0 can then be calculated.

[0073] Figure 4 It represents AC voltage V A AC voltage V B AC voltage V C A diagram showing an example of the waveform. In the electrostatic capacitive sensor 100, under AC voltage V... A AC voltage V B AC voltage V C V A ≥V B >V C The relationship. That is, the AC voltage V A The amplitude is the AC voltage V B The amplitude is above, and the AC voltage V C The amplitude is less than the AC voltage V B The amplitude.

[0074] Here, although as an example, the AC voltage V is used... A AC voltage V B AC voltage V C Assuming they are different, such as Figure 4 As shown, it has V A >V B >V C The relationship, but for those with V A ≥V B>V C The reasons for the relationship should be explained.

[0075] In equation (2), among the capacitances of each part, capacitances Cf and Cs vary according to the degree of proximity and pressure. In order to detect the proximity, contact, and pressure of the fingertip FT towards the cover 101 on the detection electrode 111 by means of only the output voltage V0, it is sufficient to increase the voltage V0 in the order of proximity, contact, and pressure.

[0076] Here, the output voltage V0 is determined using threshold values ​​V1 and V2 to indicate whether there is proximity or contact. Regarding whether there is pressure, [the following is used]. Figure 5 The determination will be made using the methods described later. Here, the methods for determining whether there is proximity or contact will be explained.

[0077] When setting the proximity threshold V1 and the contact threshold V2, these are set to have a relationship of V1 < V2. Furthermore, proximity is detected when the amplitude V0 of the output voltage V0 is greater than V1 but less than V2, and contact is detected when the amplitude V0 of the output voltage V0 is greater than V2. In this way, proximity and contact of the fingertip FT towards the cover 101 can be detected based on the amplitude V0 of the output voltage V0.

[0078] Here, Cf×V in equation (2) B The value of the term increases as the fingertip FT approaches the cover 101. Additionally, to ensure that (V) in equation (2)... B -V C The value of the )×Cs term increases as the cover 101 is pressed by the fingertip FT, and the AC voltage V B AC voltage V c That's it. Therefore, the AC voltage V B AC voltage V C Established.

[0079] Additionally, by applying an AC voltage V to the drive electrode 112 A AC voltage V B This reduces the impact of parasitic capacitance between the detection electrode 111 and ground, as well as capacitive coupling other than the capacitive coupling between the detection electrode 111 and the shielding electrode 130 directly below it. Furthermore, when the impact of parasitic capacitance between the detection electrode 111 and ground is small, the AC voltage V... A With AC voltage V B They can also be equal. Therefore, the AC voltage V A ≥ AC voltage V B That's all.

[0080] By using such an AC voltage V A ≥ AC voltage V BThe relationship allows for the approach, contact, and pressing of the fingertip FT towards the cover 101, enabling Cf×V in equation (2) to... B The value of the term and (V) in equation (2) B -V C The increase in the value of the )×Cs term is stably reflected in the output voltage V0. Here, as an example, assume that the AC voltage V A AC voltage V B The relationship.

[0081] In addition, regarding whether or not there is pressure, in order to use Figure 5 The determination can be made using the method described later, or by using (V) in equation (2). B -V C The value of the )×Cs term does not increase with pressing the cover 101 by the fingertip FT. This is because the AC voltage V B AC voltage V C Establishing (V) in equation (2) is helpful B -V C )×C s The value of the term increases as the cap 101 is pressed by the fingertip FT, so it is easy to determine the increase in the degree of pressing by corresponding to the increase in the output voltage V0. However, the AC voltage V B AC voltage V C The relationship is not necessary.

[0082] Figure 5 This represents the capacitance Cf and C in the electrostatic capacitive sensor 100. s A graph showing the time variation of the output voltage V0. Figure 5 In (A), the horizontal axis represents time (without units), and the vertical axis represents capacitances Cf and Cs (pF). Figure 5 In (A), the state where there is no fingertip FT (no operation state) within the detectable range of the electrostatic capacitance sensor 100 is time 0. As time passes, the fingertip FT approaches and contacts the surface of the cover 101, and presses the surface at a time of approximately 7.

[0083] like Figure 5 As shown in (A), time passes from time 0, and capacitances Cf and Cs increase, but the change in capacitance Cs is smaller than that of capacitance Cf. Furthermore, if the surface of cover 101 is pressed after time approximately 7, capacitance Cs increases slightly, but capacitance Cf also increases by approximately time 8.5. Therefore, it is difficult to determine whether a press has occurred based solely on capacitance Cs.

[0084] exist Figure 5 In (B), the dashed line represents the output voltage V obtained by the detection electrode 111 located at the position where the fingertip FT is pressed. 01The output voltage V is represented by a dashed line. 02 The double-dotted line indicates that V is the source of the V. 02 -V 01 The obtained voltage is represented by a solid line from V. 02 -V 01 The voltage that eliminates the offset voltage (after offset elimination). Figure 5 In (C), it indicates that it has been reduced. Figure 5 V, represented by a solid line in (B) 02 -V 01 A chart with a scale for the vertical axis (after offset removal).

[0085] Output voltage V 01 The variable amplifier circuit 140C is outputting AC voltage V. C1 The output voltage of the detection unit 150 at that time. That is, the output voltage V. 01 It is V C1 Substituting V into equation (2) C The calculated output voltage. Additionally, the output voltage V... 02 The variable amplifier circuit 140C is outputting AC voltage V. C2 The output voltage of the detection unit 150 at that time. That is, the output voltage V. 02 It is V C2 Substituting V into equation (2) C The calculated output voltage. Since V C1 >V C2 Therefore, V 01 <V 02 Therefore, V is used as the voltage difference. 02 -V 01 (>0). Voltage V 02 -V 01 From the output voltage V 02 Subtract the output voltage V from the middle 01 voltage, V 02 -V 01 (After offset elimination) is from voltage V 02 -V 0l The output voltage V is removed when there is no fingertip FT (no operation state) within the detectable range of the electrostatic capacitance sensor 100. 01 V 02 The value of the voltage (offset voltage).

[0086] Here, as an example, since the output amplitude V of the variable amplifier circuit 140C is adjusted when each detection electrode 111 is selected... C1 After applying the AC voltage, an amplitude V is applied. C2 The AC voltage, therefore the output voltage V 01 Can precede the output voltage V02 And thus, the output voltage V is obtained. 01 V 02 The operation determination unit 171 is temporarily held by the holding unit 172, and the operation determination unit 171 is based on the output voltage V held by the holding unit 172. 01 V 02 To determine whether pressure has been applied. (Shown) Figure 5 The output voltage V shown in (B) 01 Output voltage V 02 V 02 -V 01 V 02 -V 01 The graph (after offset elimination) is as follows: The output voltage V obtained from the detection electrode 111 located at the position where the fingertip FT is pressed, as the selection of each detection electrode 111 is repeatedly performed. 01 Output voltage V 02 V 02 -V 01 V 02 -V 01 The values ​​(after offset removal) are arranged in a time series.

[0087] like Figure 5 As shown in (B), although the output voltage V 01 V 02 The voltage values ​​are different, but they change in the same way over time. Additionally, as... Figure 5 As shown in (B), the voltage V 02 -V 01 and V 02 -V 01 (After offset elimination) only the voltage value is different, and the change with respect to time is equal.

[0088] exist Figure 5 The expanded representation of V in (C) 02 -V 01 (After offset elimination) the voltage rises from 0V at approximately time 7, coinciding with the point at which the fingertip FT begins to press. Therefore, if the action determination unit 171 changes the output of the variable amplifier circuit 140C to AC voltage V... C1 and V C2 The obtained output voltage V 01 and V 02 By using an appropriate threshold to determine whether a press has occurred, the influence of the change in capacitance Cf caused by the press can be eliminated, thus correctly detecting that a press has occurred.

[0089] Therefore, it is possible to provide a capacitive sensor 100 that can easily detect when the cover 101 is pressed by the fingertip FT.

[0090] Since the detection unit 150 has an operational amplifier 152, which has an inverting input terminal connected to one or more detection electrodes 111 and a non-inverting input terminal connected to the amplifier circuit 140B, and performs negative feedback operation, it can make the AC voltage V input to the non-inverting input terminal... B The signal is reflected to the inverting input terminal and applied to the detection electrode 111, thereby accurately detecting that the cover 101 was pressed by the fingertip FT.

[0091] In addition, since the output voltage V0 is represented by equation (1), it is easy to detect that the cover 101 was pressed by the fingertip FT based on the output voltage V0.

[0092] In addition, due to AC voltage V A AC voltage V C and AC voltage V B The amplitude of the vibration is set such that (V) in equation (1) is not applied when the fingertip FT is not pressed. B -V A )×Cp term and (V B -V C The amplitude V canceled out by the )×Cs term A V B and V C Therefore, in equation (2), the dynamic range of capacitor Cf can be increased.

[0093] Even in the absence of the fingertip FT (no operation state), the electrostatic capacitive sensor 100 outputs an output voltage V0 corresponding to the capacitance generated between the detection electrode 111, the drive electrode 112, and the surrounding object.

[0094] Here, when the fingertip FT begins to approach the detection electrode 111 from the inactive state, the dynamic range of the capacitor Cf is increased to facilitate the detection of the fingertip FT's approach. In the inactive state, if the AC voltage V... A AC voltage V B AC voltage V C Having (V) in equation (2) B -V A )×Cp term and (V B -V C The relationship between the cancellation of the terms ()×Cs) can increase the dynamic range of the capacitor Cf in equation (2).

[0095] Therefore, AC voltage V can also be used. A AC voltage V B and AC voltage V C Configured so that in the inactive state (V) B -V A )×Cp term and (VB -V C The amplitude V canceled by the )×Cs term A V B and V C When not in use, it is easy to detect the approach of the fingertip FT towards the cover 101.

[0096] In addition, since the amplifier circuit 140B outputs an AC voltage V to the detection electrode 111 selected by the selection unit 160B... B Therefore, the selection of the detection electrode 111 can be reliably performed with a simple structure, and the cover 101 can be easily detected by pressing it with the fingertip FT.

[0097] Furthermore, since the action determination unit 171 uses the variable amplifier circuit 140C to convert the AC voltage V C The amplitude is set to a given amplitude (e.g., V). C1 The output of the detection unit 150 (e.g., V) 01 The system detects whether a fingertip (FT) approaches or touches the cover 101, thus enabling the detection of both approach and contact in addition to pressing. Therefore, different functions can be assigned to contact and pressing, such that if contact occurs, content is selected to be displayed at the contact location using a GUI (Graphical User Interface), and if pressing occurs, the selected content is determined.

[0098] Furthermore, since the action determination unit 171 determines the AC voltage V based on the variable amplifier circuit 140C... C The amplitude changes to multiple amplitudes (e.g., V). C1 V C2 When the multiple output voltages (e.g., V) of the detection unit 150 are held by the holding unit 172, they are respectively held by the holding unit 172. 01 V 02 This allows for the determination of whether a press has occurred, thus reliably maintaining multiple output voltages (e.g., V) obtained at different timings in the time series. 01 V 02 It can accurately detect when the cap 101 is pressed by the fingertip FT.

[0099] Furthermore, when the detection unit 150 is connected to each detection electrode 111, the action determination unit 171, based on the variable amplifier circuit 140C, applies an AC voltage V to each of the connected detection electrodes 111. C The amplitude changes to multiple amplitudes (e.g., V). C1 V C2 The multiple output voltages (e.g., V) of the detection unit 150 obtained at each time are as follows. 01 V 02This allows for the determination of whether a press has occurred at the position corresponding to the connected detection electrode 111 within the cover 101. Therefore, it is possible to detect an AC voltage (e.g., V) of multiple amplitudes applied to the shielding electrode 130 while the fingertip FT is in a nearly identical position to the cover 101. C1 V C2 The capacitance Cs at the time of application of the AC voltage (e.g., V) can be used, and it is possible to use the capacitance Cs based on the applied AC voltage (e.g., V). C1 V C2 The difference in output voltage (e.g., V) C1 V C2 The difference is used to correctly detect whether the cover 101 was pressed by the fingertip FT.

[0100] In addition, due to the applied AC voltage V A The driving unit uses the adjacent surface electrode 110 of the surface electrodes 110 (excluding the detection electrode 111 included in the plurality of surface electrodes 110) as the driving electrode 112. Therefore, the proximity, contact, and pressing of the fingertip FT towards the cover 101 can be detected based on the output voltage V0 using the capacitance Cp between the detection electrode 111 and the driving electrode 112. Since the capacitance Cp between the detection electrode 111 and the driving electrode 112 is used, the proximity, contact, and pressing of the fingertip FT towards the cover 101 can be stably detected based on the output voltage V0 by using the capacitance Cp between adjacent surface electrodes 110.

[0101] Additionally, regarding AC voltage V A AC voltage V B AC voltage V C It can also have V A ≥V B >V C The relationship. Furthermore, by using an AC voltage V with such a relationship... A AC voltage V B AC voltage V C Since the output voltage V0 increases as the fingertip FT approaches, touches, and presses, the action of the fingertip FT can be easily determined based on the output voltage V0.

[0102] Furthermore, when the electrostatic capacitive sensor 100 connects the amplifier circuit 140A to the two surface electrodes 110 selected as driving electrodes 112 by the selection unit 160A, and connects the input terminal 151 to the surface electrode 110 selected as detection electrodes 111 by the selection unit 160B, it can detect the approach, contact, and pressing of the fingertip FT towards the cover 101 based on the output voltage V0 of the output terminal 155 of the detection unit 150 without switching the circuits for the detection electrode 111 and the driving electrode 112.

[0103] Furthermore, since the signals used to detect proximity, contact, and pressing are unified into an output voltage V0, the wiring connecting the multiple surface electrodes 110 to the amplifier circuit 140A, amplifier circuit 140B, variable amplifier circuit 140C, power supply circuit 145, and detection unit 150 can be minimized. Since the detection unit 150 can also be miniaturized, a capacitive sensor 100 with a simplified structure can be provided.

[0104] Furthermore, since the signals used to detect proximity, contact, and pressing are unified into an output voltage V0, the increase in the processing time required for detecting proximity, contact, and pressing can be minimized, thereby reducing the processing time for detecting proximity, contact, and pressing.

[0105] In addition, due to AC voltage V A AC voltage V B and AC voltage V C Since it is a sine wave, the output voltage V0 can be easily obtained based on equation (2) using amplifier circuit 140A, amplifier circuit 140B, variable amplifier circuit 140C, and power supply circuit 145. In addition, based on the output voltage V0 obtained in this way, the approach, contact, and pressing of the fingertip FT towards the cover 101 can be stably detected.

[0106] Furthermore, the above-mentioned amplifier circuits 140A, 140B, and 140C amplify the AC voltage of the power supply circuit 145 at a given frequency and output AC voltage V respectively. A V B V C1 and V C2 The method was explained. However, the output AC voltage V A V B V C1 and V C2 The circuit is not limited to the type described above. As long as it can align with the AC voltage V... A V B V C1 and V C2 The phase can be adjusted to an appropriate amplitude. For example, multiple power supply circuits can be set up based on the circuit that makes the phases of multiple power supplies consistent.

[0107] In addition, the above applies to AC voltage V A AC voltage V B and AC voltage V C It was explained using a sine wave approach, but the AC voltage V... A AC voltage V B and AC voltage VC It can also be a rectangular wave. In this case, the power supply circuit 145 outputs a rectangular AC voltage instead of a sinusoidal AC voltage. Even when using a rectangular wave instead of a sinusoidal wave, the proximity, contact, and pressing of the fingertip FT towards the cover 101 can be detected based on the amplitude V0 of the output voltage V0.

[0108] In addition, the above applies to the use of, for example Figure 1 The arrangement of the plurality of surface-side electrodes 110 in a matrix configuration has been described. However, the plurality of surface-side electrodes 110 included in the capacitive sensor 100 is not limited to this structure. For example, it could also be a structure in which the plurality of surface-side electrodes 110 detect the approach, contact, and pressing of the fingertip FT toward the cover 101 based on the change in the capacitive capacitance of a plurality of electrodes extending in the row direction (X direction) and arranged in the Y direction, and a plurality of electrodes extending in the column direction (Y direction) and arranged in the X direction. The plurality of electrodes extending in the row direction (X direction) and arranged in the Y direction, and the plurality of electrodes extending in the column direction (Y direction) and arranged in the X direction, could also be patterned as diamond-shaped electrodes in top view.

[0109] <Implementation Method 2>

[0110] Figure 6 This diagram illustrates the capacitive capacitance sensor 200 according to Embodiment 2. The capacitive capacitance sensor 200 includes a detection electrode 111, a drive electrode 112, an elastic dielectric 120, a shielding electrode 130, an amplifier circuit 140A, an amplifier circuit 140B, a variable amplifier circuit 140C, a power supply circuit 145, a detection unit 150, and switching switches 261 and 262. Switches 261 and 262 are an example of a selection unit that selects one or more detection electrodes 111 from the surface electrode 110. Figure 6 In the diagram, the detection electrode 111, driving electrode 112, elastic dielectric 120, and shielding electrode 130 are shown as planar structures within the XY plane. Furthermore, in... Figure 6 The middle section omits cover 101.

[0111] In Embodiment 2, the capacitive sensor 200 includes two surface electrodes 110, one of which is used as a detection electrode 111 and the other as a drive electrode 112. Furthermore, the same reference numerals are used for the same structural elements as in the capacitive sensor 100 of Embodiment 1, and their descriptions are omitted.

[0112] Both switch 261 and 262 are 3-terminal switches, capable of switching the connection destination between amplifier circuit 140A and input terminal 151 via detection electrode 111 and drive electrode 112. Figure 6The following states are indicated: By switching switches 261 and 262, the surface-side electrode 110 on the -X direction side is used as the detection electrode 111 and connected to the input terminal 151, and the surface-side electrode 110 on the +X direction side is used as the drive electrode 112 and connected to the amplifier circuit 140A. However, if the switching switches 261 and 262 are switched so that the surface-side electrode 110 on the +X direction side is connected to the input terminal 151 and the surface-side electrode 110 on the -X direction side is connected to the amplifier circuit 140A, then the surface-side electrode 110 on the -X direction side can be used as the detection electrode 111 and the surface-side electrode 110 on the +X direction side can be used as the drive electrode 112.

[0113] If the capacitance (static capacitance) between the detection electrode 111 and the drive electrode 112 is set to Cp, then, similarly to the static capacitance sensor 100 in Embodiment 1, equation (2) holds. Therefore, if the operation determination unit 171 changes the output of the variable amplifier circuit 140C to an AC voltage V, C 1 and V C 2. The difference between the obtained output voltages V01 and V02, when used with an appropriate threshold to determine whether a press has occurred, can eliminate the influence of the change in capacitance Cf caused by the press and correctly detect that a press has occurred.

[0114] Therefore, similar to the electrostatic capacitive sensor 100 of Embodiment 1, an electrostatic capacitive sensor 200 can be provided that can easily detect when the cover 101 is pressed by the fingertip FT.

[0115] Furthermore, the action determination unit 171, based on the variable amplifier circuit 140C, converts the AC voltage V... C The amplitude is set to a given amplitude (e.g., V). C1 The output of the detection unit 150 determines whether a fingertip (FT) has approached or touched the cover 101. Therefore, it can detect both approach and contact in addition to pressing. Thus, different functions can be assigned to contact and pressing, so that if contact occurs, content is displayed at the contact location in a GUI or similar format, and if pressing occurs, the selected content is confirmed.

[0116] Furthermore, when the surface electrode 110 on the -X direction side is used as the detection electrode 111 and the surface electrode 110 on the +X direction side is used as the drive electrode 112, the fingertip FT can also be sensed to approach, contact with, or press the detection electrode 111 based on the output voltage V0 of the output terminal 155 of the detection unit 150.

[0117] Therefore, by using one of the two surface electrodes 110 as a detection electrode 111 and the other as a drive electrode 112, it is possible to sense the approach, contact, and pressure of the fingertip FT toward the detection electrode 111.

[0118] Additionally, the electrostatic capacitance sensor 200 includes switching switches 261 and 262, which serve as selection units for choosing the detection electrode 111 from the surface electrode 110. The amplifier circuit 140B outputs an AC voltage V to the detection electrode 111 selected by the switching switches 261 and 262. B Therefore, by adding switch 261, 262 as a minimum circuit, one of the two surface electrodes 110 can be switched to either the detection electrode 111 or the drive electrode 112, and the approach, contact, and pressing of the fingertip FT (the object to be detected) towards the cover 101 can be detected based on the output voltage V0.

[0119] Furthermore, in Embodiment 2, the method of using one of the two surface electrodes 110 as a detection electrode 111 and the other as a drive electrode 112 was described. However, for example, when the capacitive sensor 200 includes three surface electrodes 110 arranged in the X direction, the following can be used. When three switches, identical to switches 261 and 262, are connected to the three surface electrodes 110, and the surface electrode 110 on the -X direction side is used as the detection electrode 111, the central surface electrode 110 in the X direction and the surface electrode 110 on the +X direction side are used as drive electrodes 112 to sense the approach, contact, and pressure of the fingertip FT towards the detection electrode 111. When the surface electrode 110 on the +X direction side is used as the detection electrode 111, the process is reversed.

[0120] When the central surface electrode 110 in the X direction is used as the detection electrode 111, the surface electrodes 110 on the -X and +X directions are used as drive electrodes 112 to sense the fingertip FT approaching, contacting, or pressing the detection electrode 111. Alternatively, one of the surface electrodes 110 other than the detection electrode 111 can be used as the drive electrode 112, with the remaining surface electrodes 110 floating in contact.

[0121] Furthermore, when the number of surface electrodes 110 is four or more, for example, by setting multiple such... Figure 6 The electrostatic capacitive sensor 200 shown can sense approach, contact, and pressure toward the surface electrode 110 selected as the detection electrode 111.

[0122] <Implementation Method 3>

[0123] Figure 7This is a diagram showing the electrostatic capacitive sensor 300 according to Embodiment 3. The electrostatic capacitive sensor 300 includes a cover 101, a substrate 102, a detection electrode 111, an elastic dielectric 120, a shielding electrode 130, an amplifier circuit 140A, an amplifier circuit 140B, a variable amplifier circuit 140C, a power supply circuit 145, a detection unit 150, a capacitor 370, and a terminal 380.

[0124] In Embodiment 3, the capacitive sensor 300 will be described in a manner that includes a surface electrode 110 and is used as a detection electrode 111. Furthermore, the same reference numerals are used for structural elements identical to those in the capacitive sensor 100 of Embodiment 1, and their descriptions are omitted.

[0125] A capacitor 370 is provided instead of the capacitor Cp between the detection electrode 111 and the two drive electrodes 112 in Embodiment 1, and has a capacitance Cp3. As an example, the capacitance Cp3 is equal to the capacitance Cp in Embodiment 1.

[0126] Terminal 380 is an example of a driving unit, coupled to the detection electrode 111 via capacitor Cp3. In this embodiment, terminal 380 replaces the two driving electrodes 112 in embodiment 1 to output AC voltage V from amplifier circuit 140A. A Structural elements.

[0127] Since the capacitance Cf between the detection electrode 111 and the fingertip FT, and the capacitance Cs between the detection electrode 111 and the shielding electrode 130 are the same as the capacitance Cf and capacitance Cs in Embodiment 1, the output voltage V0 of the output terminal 155 of the detection unit 150 can be shown in the same way as in Embodiment 1, using Equation (2).

[0128] Therefore, if the action determination unit 171 determines that the output of the variable amplifier circuit 140C is changed to an AC voltage V... C1 and V C2 The obtained output voltage V 01 and V 02 By using an appropriate threshold to determine whether a press has occurred, the influence of the change in capacitance Cf caused by the press can be eliminated, thus correctly detecting that a press has occurred.

[0129] Therefore, it is possible to provide a capacitive sensor 300 that can easily detect when the cover 101 is pressed by the fingertip FT, just like the capacitive sensor 100 of Embodiment 1.

[0130] Furthermore, the action determination unit 171, based on the variable amplifier circuit 140C, converts the AC voltage V... C The amplitude is set to a given amplitude (e.g., V). C1The output of the detection unit 150 determines whether a fingertip (FT) has approached or touched the cover 101. Therefore, it can detect both approach and contact in addition to pressing. Thus, different functions can be assigned to contact and pressing, so that if contact occurs, content is displayed at the contact location in a GUI or similar format, and if pressing occurs, the selected content is confirmed.

[0131] Furthermore, in Embodiment 3, a capacitive sensor 300 using a single surface electrode 110 as a detection electrode 111 was described. However, in the case where multiple surface electrodes 110 exist, for example, by providing multiple... Figure 7 The electrostatic capacitive sensor 300 shown uses each of the surface electrodes 110 as detection electrodes 111 to sense proximity, contact, and pressure towards each detection electrode 111.

[0132] The above describes an exemplary embodiment of the electrostatic capacitive sensor of the present invention. However, the present invention is not limited to the specific disclosed embodiments. Various modifications and alterations can be made without departing from the claims.

[0133] Furthermore, this international application claims priority based on Japanese Patent Application No. 2021-161423, filed on September 30, 2021, the entire contents of which are incorporated herein by reference.

[0134] -Explanation of Figure Markers-

[0135] 100, 200, 300 electrostatic capacitive sensors

[0136] 101 Cover

[0137] 102 substrate

[0138] 110 Surface Electrode

[0139] 111 Detection Electrode

[0140] 112 Driving electrode

[0141] 120 elastic dielectric

[0142] 130 Shielding Electrode

[0143] The 140A amplifier circuit (and the power supply circuit 145 are both examples of the first voltage output section)

[0144] The 140B amplifier circuit (and the 145 power supply circuit are both examples of the third voltage output section)

[0145] The 140C variable amplifier circuit (and the 145 power supply circuit are both examples of the second voltage output section)

[0146] 145 Power Supply Circuit

[0147] 150 Testing Department

[0148] 151 Input Terminals

[0149] 152 Operational Amplifier

[0150] 153 Capacitor

[0151] 154 resistor

[0152] 155 Output Terminal

[0153] 160A, 160B Selection Section

[0154] 170 Control device

[0155] 171 Motion Judgment Department

[0156] 172 Maintenance Department

[0157] 261, 262 Toggle Switches (An example of a selection unit)

[0158] 370 capacitor

[0159] 380 terminal.

Claims

1. A capacitive sensor, characterized in that, Include: One or more surface electrodes, including one or more detection electrodes; A cover is disposed on the surface of the one or more surface electrodes; An elastic dielectric is disposed on the back side of the one or more surface electrodes; A shielding electrode is disposed on the back side of the elastic dielectric; The first voltage output section outputs a first AC voltage to the drive section that is coupled to the one or more detection electrodes via a capacitor; The second voltage output section outputs a second AC voltage that is in phase with the first AC voltage to the shielding electrode; The detection unit is connected to one or more detection electrodes and detects the output corresponding to the capacitance of one or more surface electrodes; and The motion determination unit determines the motion of the detected object based on the output of the detection unit. The second voltage output section can change the amplitude of the second AC voltage. The action determination unit determines whether the object being detected has been pressed against the cover based on the difference between the two outputs of the detection unit obtained when the amplitude of the second AC voltage is changed to multiple amplitudes by the second voltage output unit. The amplitude of the first AC voltage is constant.

2. The electrostatic capacitive sensor according to claim 1, wherein, The electrostatic capacitance sensor further includes: a third voltage output section, which outputs a third AC voltage that is in phase with the first AC voltage. The detection unit includes an operational amplifier with an inverting input terminal connected to one or more detection electrodes and a non-inverting input terminal connected to the third voltage output unit, and performs negative feedback operation.

3. The electrostatic capacitive sensor according to claim 2, wherein, If the capacitance between the detection electrode and the object being detected is set to Cf, the capacitance between the detection electrode and the driving unit is set to Cp, the capacitance between the detection electrode and the shielding electrode is set to Cs, the first AC voltage is set to VA, the second AC voltage is set to VC, and the third AC voltage is set to V... B Let the capacitance of the capacitor connected between the output terminal and the non-inverting input terminal of the operational amplifier be Cq, and let the output voltage of the output terminal be V0. Then the output voltage V0 is represented by the following formula (1). [Mathematical Expression 1] 。 4. The electrostatic capacitive sensor according to claim 3, wherein, The amplitudes of the first AC voltage, the second AC voltage, and the third AC voltage are set such that (V) in equation (1) are such that (V) are not pressed on the object being tested. B -VA)×Cp terms and (V B The amplitudes VA and V canceled out by the -VC)×Cs term are... B And VC.

5. The electrostatic capacitive sensor according to any one of claims 2 to 4, wherein, The electrostatic capacitance sensor further includes a selection unit for selecting one or more detection electrodes from the one or more surface-side electrodes. The third voltage output unit outputs the third AC voltage to one or more detection electrodes selected by the selection unit.

6. The electrostatic capacitive sensor according to any one of claims 1 to 4, wherein, The action determination unit determines whether the detected object has approached or contacted the cover based on the output of the detection unit when the amplitude of the second AC voltage is set to a given amplitude by the second voltage output unit.

7. The electrostatic capacitive sensor according to any one of claims 1 to 4, wherein, The electrostatic capacitance sensor further includes a holding unit to hold the output of the detection unit. The action determination unit determines that the pressing has been performed based on the multiple outputs of the detection unit held by the holding unit when the amplitude of the second AC voltage is changed to multiple amplitudes by the second voltage output unit.

8. The electrostatic capacitive sensor according to any one of claims 1 to 4, wherein, The one or more detection electrodes are multiple detection electrodes, and the one or more surface-side electrodes are multiple surface-side electrodes that include the multiple detection electrodes. The detection unit is sequentially connected to each of the plurality of detection electrodes, and, while connected to each detection electrode, detects the output corresponding to the capacitance of the plurality of surface electrodes. The action determination unit determines, based on the multiple outputs of the detection unit obtained by the second voltage output unit when the amplitude of the second AC voltage is changed to multiple amplitudes for each connected detection electrode, that the pressing has occurred at the position corresponding to the connected detection electrode in the cover.

9. The electrostatic capacitive sensor according to any one of claims 1 to 4, wherein, The one or more surface-side electrodes are multiple surface-side electrodes. The driving unit is at least one of the surface electrodes included in the plurality of surface electrodes, other than the one or more detection electrodes.

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