Capacitive Sensor

Abstract

Provided is an electrostatic capacitance sensor capable of accurately detecting a press performed by a detection target object.　The electrostatic capacitance sensor includes one or a plurality of front side electrodes including a detecting electrode, a cover disposed on a front side of the one or plurality of front side electrodes, a resilient dielectric provided on a rear side of the one or plurality of front side electrodes, a shielding electrode provided on the rear side of the resilient dielectric, a first voltage output unit for outputting a first alternating current voltage to a drive unit that is linked to the detecting electrode via a capacitor, a second voltage output unit for outputting a second alternating current voltage having the same phase as the first alternating current voltage to the shielding electrode, a detecting unit which is connected to the detecting electrode to detect an output corresponding to a capacitance of the one or plurality of front side electrodes, and an operation determining unit for determining an operation of the detection target object in accordance with the output of the detecting unit, wherein: the second voltage output unit is capable of changing an amplitude of the second alternating current voltage; and the operation determining unit determines that a pressing operation on the cover has been performed by means of the detection target object, on the basis of a plurality of outputs of the detecting unit obtained respectively when the second voltage output unit changes the amplitude of the second alternating current voltage to each of a plurality of amplitudes.

Description

[Technical field]

[0001] The present invention relates to a capacitive sensor. [Background technology]

[0002] Conventionally, there has been a display device having a light-emitting element layer, a plurality of first electrodes each extending in a first direction and adjacent to each other in a second direction intersecting the first direction, a plurality of second electrodes each extending in the second direction above the plurality of first electrodes and adjacent to each other in the first direction, an insulating elastic layer interposed between the plurality of first electrodes and the plurality of second electrodes to ensure a gap, and a sensing circuit.

[0003] The sensing circuit measures a first physical quantity corresponding to a first capacitance parasitic on each of the electrode groups consisting of the plurality of first electrodes and the plurality of second electrodes, and detects a significant change in the first capacitance due to the approach of a conductor including a finger when the obtained first measured value falls outside a first range. The sensing circuit further measures a second physical quantity corresponding to a second capacitance between each of the plurality of first electrodes and each of the plurality of second electrodes, and detects a significant change in the second capacitance due to compression of the insulating elastic layer by a pressing force when the obtained second measured value falls outside a second range (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 10,429,984B2 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in conventional display devices, both the first capacitance and the second capacitance are affected by both the proximity of a finger and the pressure, and therefore it is not possible to accurately measure the pressure.

[0006] It is therefore an object of the present invention to provide a capacitance sensor that can accurately detect being pressed by an object to be detected. [Means for solving the problem]

[0007] a first voltage output unit configured to output a first AC voltage to a drive unit capacitively coupled to the one or more detection electrodes; a second voltage output unit configured to output a second AC voltage to the shield electrode, the second AC voltage having the same phase as the first AC voltage; a detection unit connected to the one or more detection electrodes and detecting an output corresponding to the capacitance of the one or more front-side electrodes; and an operation determination unit configured to determine an operation of an object to be detected in accordance with an output of the detection unit, wherein the second voltage output unit is capable of changing an amplitude of the second AC voltage, and the operation determination unit determines that the object to be detected has pressed the cover based on a plurality of outputs of the detection unit obtained when the second voltage output unit changes the amplitude of the second AC voltage to a plurality of amplitudes. Effect of the Invention

[0008] It is possible to provide a capacitance sensor that can accurately detect being pressed by a detection object. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram showing a planar configuration of a capacitance sensor 100 according to a first embodiment. [Diagram 2] 1 is a diagram showing a cross-sectional structure of a portion of a capacitance sensor 100. FIG. [Diagram 3] FIG. 2 is a diagram showing an equivalent circuit of the capacitance sensor 100. [Figure 4] 1 is a diagram showing an example of waveforms of an AC voltage VA, an AC voltage VB, and an AC voltage VC. [Diagram 5] 4 is a diagram showing changes over time in capacitances Cf, Cs and an output voltage V0 in the capacitance sensor 100. FIG. [Figure 6] 1 is a diagram showing a capacitance sensor 200 according to a second embodiment. FIG. [Figure 7] FIG. 11 is a diagram showing a capacitance sensor 300 according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment to which a capacitance sensor of the present invention is applied will be described.

[0011] <Embodiment 1> FIG. 1 is a diagram showing a planar configuration of the capacitance sensor 100 of the first embodiment. In the following, an XYZ coordinate system is defined and described. 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 mutually orthogonal. In the following, for convenience of description, the -Z direction side may be referred to as the lower side or bottom, and the +Z direction side as the upper side or top, but this does not represent a universal up-down relationship. In addition, the top surface side of a certain component is the front side, and the bottom surface side is the back side. In addition, a plan view refers to an XY plane view. In the following, the length, width, thickness, etc. of each part may be exaggerated to make the configuration easier to understand.

[0012] The capacitance sensor 100 includes a cover 101 and a plurality of front-side electrodes 110. The cover 101 is disposed on the front side of the plurality of front-side electrodes 110. The capacitance sensor 100 also includes an action determination unit and the like that determines whether a user's fingertip or the like has approached, contacted, or pressed the cover 101; however, this is omitted in Fig. 1, which shows a planar configuration of the cover 101 and the plurality of front-side electrodes 110.

[0013] The cover 101 is, for example, a plate-like member made of transparent glass or resin that can bend when pressed from above, and is rectangular in plan view. The upper surface is an operation surface on which a user touches with a fingertip or the like to perform operation input. The user can also press the upper surface of the cover 101 downward. The cover 101 is provided as a top panel that covers the upper surface of the capacitance sensor 100.

[0014] The multiple front side electrodes 110 are disposed on the lower surface side of the cover 101, and are arranged in a matrix in the X and Y directions. As an example, the multiple front side electrodes 110 are independent of each other, and are connected to a detection unit (to be described later) via wiring (not shown) that is routed between each other in a plan view.

[0015] In FIG. 1, the multiple front electrodes 110 are shown transparently. The multiple front electrodes 110 are formed of transparent electrodes such as ITO (Indium Tin Oxide). Note that, here, a form in which the cover 101 and the multiple front electrodes 110 are transparent will be described assuming that a display panel such as a liquid crystal or organic EL (Electroluminescence) panel is disposed below the capacitance sensor 100. However, in a case in which a display panel is not disposed, for example, the cover 101 and the multiple front electrodes 110 do not need to be transparent and may be made of a conductive material. In this case, the multiple front electrodes 110 may be a metal plate or the like.

[0016] Fig. 2 is a diagram showing a cross-sectional structure of a portion of the capacitance sensor 100. Fig. 2 shows the cross-sectional structure of a portion where three front electrodes 110 arranged in the X direction are present. Here, as an example, a form in which a user performs an operational input to the capacitance sensor 100 with a fingertip FT will be described. The fingertip FT is an example of an object to be detected. The user performs an operational input by touching (contacting) the cover 101 with the fingertip FT.

[0017] In addition to the cover 101 and the front electrode 110, the capacitance sensor 100 further includes an elastic dielectric 120, a shield 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 predetermined amplitude, and outputs an AC voltage to the amplifier circuit 140A, the amplifier circuit 140B, and the variable amplifier circuit 140C. The amplifier circuit 140A and the power supply circuit 145 are an example of a first voltage output unit, the amplifier circuit 140B and the power supply circuit 145 are an example of a third voltage output unit, and the variable amplifier circuit 140C and the power supply circuit 145 are an example of a second voltage output unit. The control device 170 has an operation determination unit 171 and a holding unit 172. The capacitance sensor 100 further includes a substrate 102.

[0018] As an example, the selection unit 160A selects two of the multiple front side electrodes 110 as the connection destination of the amplifier circuit 140A. Also, as an example, the selection unit 160B selects one of the multiple front side electrodes 110 as the connection destination of the amplifier circuit 140B and the detection unit 150. Here, it is assumed that the selection unit 160B selects the central front side electrode 110 of the three front side electrodes 110 shown in FIG. 2 and connects it to the amplifier circuit 140B and the detection unit 150. Also, it is assumed that the selection unit 160A selects the two front side electrodes 110 at both ends of the three front side electrodes 110 shown in FIG. 2 and connects it to the amplifier circuit 140A.

[0019] 2, the central surface side electrode 110 is a detection electrode 111, and the two surface side electrodes 110 on either side of the detection electrode 111 are drive electrodes 112. The drive electrode 112 is an example of a drive unit. For this reason, the detection electrode 111 and the drive electrode 112 are denoted by the reference symbol 110 in parentheses.

[0020] The detection electrode 111 is a surface side electrode 110 selected by the selection unit 160B from among the multiple surface side electrodes 110 and connected to the amplifier circuit 140B and the detection unit 150. The drive electrode 112 is a surface side electrode 110 selected by the selection unit 160A from among the multiple surface side electrodes 110 and connected to the amplifier circuit 140A. In the following, the term "surface side electrode 110" refers to a case where the detection electrode 111 and the drive electrode 112 are not particularly distinguished from each other, and a case where the surface side electrode 110 other than the detection electrode 111 and the drive electrode 112 is described.

[0021] The detection electrodes 111 are electrodes used to detect the proximity, contact, and pressure of the user's fingertip FT to the cover 101. The capacitance sensor 100 detects the proximity, contact, and pressure of the fingertip FT by selecting the front electrodes 110 one by one in turn as the detection electrodes 111 by the selection unit 160B and detecting the capacitance. At this time, the detection electrode 111 is supplied with an AC voltage V B is applied via the detection unit 150. B is an example of a third AC voltage. When the operation determination unit 171 determines that a contact or pressure has been applied to the detection electrode 111 selected by the selection unit 160B, this means that an operation input has been applied to the position (coordinates) corresponding to the detection electrode 111.

[0022] Here, a form in which the multiple front side electrodes 110 are selected one by one in sequence as the detection electrodes 111 will be described, but the selection unit 160B may simultaneously select two or more non-adjacent front side electrodes 110 as the detection electrodes 111 to simultaneously detect the proximity, contact, and pressure of the fingertip FT by the two or more detection electrodes 111. Therefore, the multiple front side electrodes 110 include one or more detection electrodes 111.

[0023] The driving electrodes 112 are the front side electrodes 110 located on both sides of the detection electrode 111 in the X direction. When the selection unit 160B selects the front side electrodes 110 one by one in order as the detection electrodes 111, the capacitance sensor 100 selects two front side electrodes 110 located on both sides of the detection electrode 111 in the X direction as two driving electrodes 112 by the selection unit 160A.

[0024] When the detection electrode 111 detects the proximity, contact, and pressure of the fingertip FT, the driving electrode 112 receives an AC voltage V A is applied. AC voltage V A is an example of a first AC voltage having an amplitude of V A (V). Note that, here, a form in which two front side electrodes 110 located on both sides of the detection electrode 111 in the X direction are used as the driving electrodes 112 will be described, but a total of four front side electrodes 110, including two front side electrodes 110 located on both sides of the detection electrode 111 in the X direction and two front side electrodes 110 located on both sides of the detection electrode 111 in the Y direction, may be used as the driving electrodes 112.

[0025] Furthermore, for example, when a surface side electrode 110 located at an end in the X direction is used as the detection electrode 111, two surface side electrodes 110 adjacent to the detection electrode 111 in the Y direction may be used as the two drive electrodes 112, or the surface side electrode 110 adjacent to the detection electrode 111 on the +X direction side and the surface side electrode 110 adjacent to the detection electrode 111 on the -Y direction side or +Y direction side may be used as the two drive electrodes 112. When a surface side electrode 110 located at a corner of a plurality of surface side electrodes 110 arranged in a matrix is ​​used as the detection electrode 111, the surface side electrode 110 adjacent to the detection electrode 111 in the X direction and the surface side electrode 110 adjacent to the detection electrode 111 in the Y direction may be used as the two drive electrodes 112.

[0026] The elastic dielectric 120 is provided on the back side (below) of the multiple front electrodes 110 (see FIGS. 1 and 2). The elastic dielectric 120 is a transparent, elastically deformable dielectric material, for example, made of urethane resin. The elastic dielectric 120 is provided at a position overlapping all of the multiple front electrodes 110 in a plan view, and has a uniform thickness in the Z direction. Since the elastic dielectric 120 is elastically deformable, when a user presses downward with a fingertip FT against a portion of the upper surface of the cover 101 directly above the detection electrode 111, the elastic dielectric 120 flexes and contracts, causing the detection electrode 111 to be slightly displaced downward.

[0027] The shield electrode 130 is provided below the elastic dielectric 120 while being provided on the upper surface of the substrate 102. That is, the shield electrode 130 is provided on the rear side of the plurality of front electrodes 110 with the elastic dielectric 120 sandwiched between the shield electrode 130 and the plurality of front electrodes 110. The shield electrode 130 is provided to shield the plurality of front electrodes 110 from noise and to suppress parasitic capacitance with the ground, and is coupled to the power supply circuit 145 and amplified by the variable amplifier circuit 140C. C1 Or V C2 is applied. AC voltage V C1 and V C2 are both examples of the second AC voltage and examples of second AC voltages with a plurality of amplitudes. The shield electrode 130 is made of a transparent conductive material such as an ITO film, for example. The substrate 102 is a transparent substrate that holds the shield electrode 130. For example, in the case where a display panel is not disposed underneath, the shield electrode 130 and the substrate 102 that holds the shield electrode 130 do not need to be transparent.

[0028] The amplifier circuit 140A converts the AC voltage output from the power supply circuit 145 into an AC voltage V A and outputs the amplified voltage V to the driving electrodes 112. The amplifier circuit 140A is configured, for example, to be selectively connectable to all of the plurality of front side electrodes 110 via a selection unit 160A, and the selection unit 160A switches the wiring connections between the amplifier circuit 140A and all of the plurality of front side electrodes 110 to connect the amplifier circuit 140A to two front side electrodes 110 selected as the driving electrodes 112, and outputs an AC voltage VA In addition, since two or more front side electrodes 110 that are not adjacent to each other may be simultaneously selected as detection electrodes 111 to simultaneously detect the proximity, contact, and pressure of the fingertip FT, the amplifier circuit 140A outputs an AC voltage V A will be output.

[0029] The amplifier circuit 140B is connected to the non-inverting input terminal (+) of the operational amplifier 152 of the detection unit 150, and converts the AC voltage output from the power supply circuit 145 into an AC voltage V B The operational amplifier 152 is an example of an operational amplifier. B has an amplitude of V B is the AC voltage, and the AC voltage V A Below (V A ≧V B ) voltage. Also, AC voltage V B The frequency of AC voltage V A The frequency is equal to the AC voltage V A The amplifier circuit 140B applies an AC voltage V B This will be explained in detail later.

[0030] The variable amplifier circuit 140C is connected to the shield electrode 130 and converts the AC voltage output from the power supply circuit 145 into an AC voltage V C1 Or V C2 The AC voltage V C1 and V C2 have amplitudes of V C1 and V C2 The variable amplifier circuit 140C can change the amplitude of the second AC voltage to a plurality of amplitudes by controlling the amplification factor by the control device 170. Here, the AC voltage output from the power supply circuit 145 is set to the AC voltage V C1 Or V C2 (V C1 >V C2 ) and output the AC voltage V C1 and VC2 The amplitude of V C1 and V C2 is the AC voltage V B The amplitude of V B Less than (V B >V C1 >V C2 ) and AC voltage V A and AC voltage V B The variable amplifier circuit 140C changes the amplitude of the AC voltage to V C1 Or V C2 The reason why the capacitance (electrostatic capacitance) Cs between the detection electrode 111 and the shield electrode 130 can be changed is because the capacitance Cs is detected by AC voltages of two different amplitudes. The details will be described later.

[0031] Power supply circuit 145 outputs an AC voltage of a predetermined frequency. Amplification circuit 140A, amplification circuit 140B, and variable amplification circuit 140C are connected to the output side of power supply circuit 145. The AC voltage of the predetermined frequency output by power supply circuit 145 is input to and amplified by amplification circuit 140A, amplification circuit 140B, and variable amplification circuit 140C. Therefore, the AC voltage V A , V B , V C1 and V C2 The frequencies are equal and the phases are equal.

[0032] The detection unit 150 has an input terminal 151, an operational amplifier 152, a capacitor 153, a resistor 154, and an output terminal 155. The detection unit 150 uses the detection electrodes 111 to detect the proximity, contact, and pressure of the user's fingertip FT.

[0033] As an example, the input terminal 151 is configured to be selectively connectable to all of the plurality of front side electrodes 110 by the selection unit 160B, and is connected to the detection electrode 111 selected by the selection unit 160B by switching the wiring in the selection unit 160B. The input terminal 151 applies an AC voltage V B Output.

[0034] The operational amplifier 152 has an inverting input terminal (-) connected to the detection electrode 111 selected by the selection unit 160B via the input terminal 151 of the detection unit 150, and is connected to the amplifier circuit 140B to receive an AC voltage V B and an output terminal connected to output terminal 155. Operational amplifier 152 performs negative feedback operation using feedback elements capacitor 153 and resistor 154, and performs amplification operation so that the voltage difference between the inverting input terminal (-) and the non-inverting input terminal (+) becomes zero. Therefore, the voltage at the inverting input terminal (-) becomes equal to the voltage applied to the non-inverting input terminal (+) due to a virtual short circuit of operational amplifier 152 as a non-inverting amplifier circuit. As a result, an AC voltage V is applied to detection electrode 111. B is applied.

[0035] The capacitor 153 is connected between the inverting input terminal (-) and the output terminal of the operational amplifier 152. The capacitance (electrostatic capacitance) of the capacitor 153 is Cq. The resistor 154 is connected in parallel to the capacitor 153. The resistance value of the resistor 154 is Rq.

[0036] The output terminal 155 is connected to the output terminal of the operational amplifier 152 and is also connected to the control device 170. The output voltage of the output terminal 155 is V0. The operational amplifier 152 performs negative feedback operation using the feedback elements, ie, the capacitor 153 and the resistor 154, so that the voltage of the inverting input terminal (-) becomes equal to the voltage applied to the non-inverting input terminal (+) due to a virtual short circuit. Therefore, the input terminal 151 is supplied with an AC voltage V B is output, and an AC voltage V is applied to the detection electrode 111 via the selection unit 160B. B is applied.

[0037] The selection unit 160A has an input terminal connected to the amplifier circuit 140A and a plurality of output terminals connected to all of the plurality of front side electrodes 110, and switches the connection destination of the input terminal to two output terminals connected to two of the plurality of front side electrodes 110 in accordance with a command input from the control device 170. In this manner, the selection unit 160A selects the two front side electrodes 110 as the driving electrodes 112. The selection unit 160A selects the AC voltage V input from the amplifier circuit 140A. A to the two drive electrodes 112. As such a selection section 160A, for example, a selector can be used.

[0038] The selection unit 160B has an input terminal connected to the input terminal 151 of the detection unit 150 and a plurality of output terminals connected to all of the plurality of front side electrodes 110, and switches the connection destination of the input terminal to one output terminal connected to one of the plurality of front side electrodes 110 in accordance with a command input from the control device 170. In this way, the selection unit 160B selects one front side electrode 110 as the detection electrode 111. The selection unit 160B selects the AC voltage V B to the detection electrode 111. As such a selection unit 160B, for example, a selector can be used.

[0039] The control device 170 is realized by a computer including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), an input / output interface, an internal bus, and the like. The control device 170 has an operation determination unit 171 and a holding unit 172. In addition to the operation determination unit 171 and the holding unit 172, the control device 170 also has a gain (AC voltage V C1 Or V C2 The operation determination unit 171 represents one function of the control device 170 as a block, and the holding unit 172 represents the RAM of the control device 170 functionally.

[0040] The motion determination unit 171 detects the proximity, contact, and pressure of the fingertip FT based on the output voltage V0 of the output terminal 155 of the detection unit 150. A specific detection method will be described later.

[0041] The holding unit 172 temporarily holds data representing the output voltage V0 when the action determination unit 171 detects the proximity, contact, and pressure of the fingertip FT based on the output voltage V0. The details of this will be described later.

[0042] Here, the multiple front side electrodes 110 are arranged at equal intervals in the X direction and the Y direction, and a capacitance (electrostatic capacitance) exists between adjacent front side electrodes 110. That is, the detection electrode 111 and the drive electrode 112 are coupled via a capacitance. In other words, the drive electrode 112 is coupled to the detection electrode 111 via a capacitance. Here, the capacitance between the detection electrode 111 and the drive electrode 112 on the -X direction side is Cp1, and the capacitance between the detection electrode 111 and the drive electrode 112 on the +X direction side is Cp2. The capacitances Cp1 and Cp2 are constant values.

[0043] Moreover, the capacitance (electrostatic capacitance) generated between the detection electrode 111 and the fingertip FT is denoted as Cf. The closer the fingertip FT is to the detection electrode 111, the larger the capacitance Cf becomes. Since the cover 101 is between the detection electrode 111 and the fingertip FT, when the fingertip FT approaches the detection electrode 111, the capacitance Cf increases until the fingertip FT comes into contact with the upper surface of the cover 101 directly above the detection electrode 111. Furthermore, when a pressing operation is performed in which the cover 101 is pressed downward with the fingertip FT, the fingertip FT deforms and the area in contact with the cover 101 increases, and the capacitance Cf further increases in accordance with the increase in pressing force.

[0044] Moreover, the capacitance (electrostatic capacitance) between the detection electrode 111 and the shield electrode 130 is denoted as Cs. When a user presses a portion of the upper surface of the cover 101 directly above the detection electrode 111 downward with a fingertip FT, the elastic dielectric 120 bends and contracts, shortening the distance d between the detection electrode 111 and the shield electrode 130. Therefore, when a pressing operation is performed, the capacitance Cs increases according to the distance d between the detection electrode 111 and the shield electrode 130.

[0045] In this way, when a pressing operation is performed by pressing the cover 101 downward with the fingertip FT, both the capacitance Cf and the capacitance Cs increase. If both the capacitance Cf and the capacitance Cs increase, it may become difficult to determine that a pressing operation has been performed. Therefore, in the capacitance sensor 100, in order to enable the operation determination unit 171 to determine that a pressing operation has been performed, the amplitude of the AC voltage output by the variable amplifier circuit 140C is increased to V with a time difference. C1 and V C2 Set to.

[0046] The AC voltage V output by the variable amplifier circuit 140C C1 Or V C2 is applied to the shield electrode 130. The capacitance Cf is the electrostatic capacitance between the detection electrode 111 and the fingertip FT, and the capacitance Cs is the electrostatic capacitance between the detection electrode 111 and the shield electrode 130. Therefore, the AC voltage V C1 , V C2 Change in (V C1 -V C2 ) affects the capacitance Cs but does not affect the capacitance Cf.

[0047] Therefore, in order to determine that a pressing operation is being performed using the detection electrode 111 selected by the selection unit 160B, the capacitance sensor 100 supplies an amplitude V C1 After outputting the AC voltage, change the amplitude to V C2 and the amplitude V C2In practice, all of the multiple front electrodes 110 arranged in a matrix are selected one by one in order by the selection unit 160B to become the detection electrodes 111, and this selection operation is repeated so that all of the front electrodes 110 are repeatedly selected as the detection electrodes 111 to determine the position of the fingertip FT and the presence or absence of a pressing operation for each detection electrode 111. In order to determine the position and presence or absence of a pressing operation for each detection electrode 111, each time one front electrode 110 is selected as the detection electrode 111 by the selection unit 160B, the variable amplifier circuit 140C applies an amplitude V C1 Immediately after outputting an AC voltage of amplitude V C2 With the fingertip FT in almost the same position, an AC voltage of amplitude V C1 The capacitance Cs and amplitude V C2 This is to detect the capacitance Cs when an AC voltage of

[0048] The operation determination unit 171 determines whether the fingertip FT is in proximity or in contact with the variable amplifier circuit 140C when the variable amplifier circuit 140C detects the AC voltage V C1 Or V C2 However, as an example, the variable amplifier circuit 140C outputs the AC voltage V C1 The motion determination unit 171 determines whether the fingertip FT is approaching or touching based on the capacitance Cf when the amplitude V C2 AC voltage and amplitude V C1 The order in which the AC voltages of the amplitude V and the amplitude V are output is not limited to the above order. C2 After outputting an AC voltage of amplitude V C1 The inverter may output an AC voltage of

[0049] Here, the amplitude of the AC voltage output by the variable amplifier circuit 140C is V C1 and V C2When the operation determination unit 171 detects a pressing operation by setting the output voltage V0 of the output terminal 155 as the input voltage V1, the output voltage V2 of the output terminal 155 is used. Therefore, before describing the method by which the operation determination unit 171 determines whether or not a pressing operation is performed, a method for determining the output voltage V0 and the AC voltage V1 will be described with reference to FIGS. A , AC voltage V B , AC voltage V C The relationship between the amplitudes of the two will now be described.

[0050] Fig. 3 is a diagram showing an equivalent circuit of the capacitance sensor 100. Fig. 3 shows an equivalent circuit of the capacitance sensor 100 excluding the control device 170. The capacitance Cf is shown as a variable capacitance since it varies depending on the distance between the fingertip FT and the detection electrode 111 and the contact area of ​​the fingertip FT. Similarly, the capacitance Cs is shown as a variable capacitance since it varies depending on the distance d between the detection electrode 111 and the shield electrode 130 due to a pressing operation. In the following, the AC voltage V C1 and V C2 If no distinction is made, the AC voltage V C It is called. V B >V C1 >V C2 Therefore, V B >V C It is.

[0051] In the capacitance sensor 100 configured as above, the following formula (1) holds. Formula (1) holds among the detection electrode 111, the drive electrode 112, and the shield electrode 130 according to the law of conservation of charge, and means that the voltage integrated by the capacitor 153 of capacitance Cq is the output voltage V0. Note that capacitance Cp=Cp1+Cp2. When four drive electrodes 112 are used, capacitance Cp is the sum of the four capacitances generated between the detection electrode 111 and the four drive electrodes 112.

[0052]

number

[0053] By modifying equation (1), the output voltage V0 of the output terminal 155 is expressed by the following equation (2).

[0054]

number

[0055] Moreover, the capacitance Cs between the detection electrode 111 and the shield electrode 130 is expressed by the following formula (3): ε0 is the dielectric constant in a 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 shield electrode 130. When the distance d becomes smaller, the capacitance Cs increases.

[0056]

number

[0057] Here, as an example, the variable amplifier circuit 140C is configured to receive an AC voltage V C1 In order to determine whether the fingertip FT is in proximity or in contact based on the capacitance Cf when the signal is output, the operation determination unit 171 determines whether the fingertip FT is in proximity or in contact based on the capacitance Cf when the signal is output ... C V C1 To find the output voltage V0, simply substitute the above.

[0058] Figure 4 shows the AC voltage V A , AC voltage V B , AC voltage V C 1 is a diagram showing an example of a waveform of an AC voltage V A , AC voltage V B , AC voltage V C Between V A ≧V B >V C That is, the AC voltage V A The amplitude of the AC voltage V B and the amplitude is equal to or greater than the AC voltage V C The amplitude of the AC voltage V B The amplitude is less than .

[0059] Here, as an example, AC voltage V A , AC voltage V B , AC voltage VC Make them different from each other, and as shown in FIG. 4, V A >V B >V C has a relationship, but V A ≧V B >V C Explain the reason for having the relationship of.

[0060] In Equation (2), among the capacitances of each part, the capacitance Cf and the capacitance Cs vary depending on the proximity degree and the pressing degree. To detect the proximity, contact, and pressing of the fingertip FT on the cover 101 on the detection electrode 111 only by the output voltage V0, it is sufficient that the output voltage V0 increases in the order of proximity, contact, and pressing.

[0061] Here, regarding the presence or absence of proximity and the presence or absence of contact, they are determined using the determination threshold values V1 and V2 with respect to the output voltage V0, and regarding the presence or absence of pressing, it is determined by the method described later using FIG. 5. Here, the determination methods for the presence or absence of proximity and the presence or absence of contact will be explained.

[0062] When the determination threshold value V1 for proximity and the determination threshold value V2 for contact are set, let them have the relationship of V1 < V2. Then, when the amplitude V0 of the output voltage V0 is equal to or greater than V1 and less than V2, proximity is detected, and when the amplitude V0 of the output voltage V0 is equal to or greater than V2, contact is detected. In this way, based on the amplitude V0 of the output voltage V0, the proximity and contact of the fingertip FT to the cover 101 can be detected.

[0063] Here, the value of the term Cf×V in Equation (2) B increases as the fingertip FT approaches the cover 101. Also, to make the value of the term (V B -V C )×Cs in Equation (2) increase as the cover 101 is pressed by the fingertip FT, it is sufficient that the alternating voltage V B > the alternating voltage V C . From these, the alternating voltage V B > the alternating voltage V C holds.

[0064] In addition, the AC voltage V applied to the driving electrode 112 A AC voltage V B By making it larger than , the effect of the parasitic capacitance between the detection electrode 111 and the ground and the capacitive coupling other than the capacitive coupling between the detection electrode 111 and the shield electrode 130 directly below it are reduced. Also, when the effect of the parasitic capacitance between the detection electrode 111 and the ground is small, the AC voltage V A and AC voltage V B Therefore, the AC voltage V A ≧AC voltage V B That's fine.

[0065] Such an AC voltage V A ≧AC voltage V B By using this relationship, in the process of the fingertip FT approaching, contacting, and pressing the cover 101, Cf × V in formula (2) can be calculated. B The value of the term and (V B -V C ) × Cs term, the increase in the value of the term can be stably reflected in the output voltage V0. A >AC voltage V B We try to satisfy the relationship.

[0066] In addition, the presence or absence of pressure is determined by the method described later with reference to FIG. 5, so (V B -V C The value of the term ) × Cs does not have to increase as the cover 101 is pressed by the fingertip FT. B >AC voltage V C This means that (V B -V C Since the value of the term (Cs) × Cs increases as the cover 101 is pressed by the fingertip FT, it becomes easier to determine the increase in the degree of pressing according to the increase in the output voltage V0. However, B >AC voltage V C The relationship is not required.

[0067] Fig. 5 is a diagram showing the change over time in capacitance Cf, Cs and output voltage V0 in capacitance sensor 100. In Fig. 5(A), the horizontal axis represents time (unitless), and the vertical axis represents capacitance Cf, Cs (pf). In Fig. 5(A), time 0 is a state in which fingertip FT is not present within the detectable range of capacitance sensor 100 (non-operation state), and as time passes, fingertip FT approaches the surface of cover 101, comes into contact with it, and presses against the surface at approximately time 7.

[0068] As shown in Fig. 5(A), as time passes from time 0, capacitances Cf and Cs increase, but the amount of change in capacitance Cs is smaller than that of capacitance Cf. Also, when the surface of cover 101 is pressed after about time 7, capacitance Cs increases slightly, but capacitance Cf also increases until about time 8.5. For this reason, it is difficult to determine whether or not a pressure is being applied from capacitance Cs alone.

[0069] FIG. 5B shows an output voltage V obtained for the detection electrode 111 at the position where the fingertip FT is pressed. 01 is shown by a dashed line, and the output voltage V 02 is shown by a dashed line, and V 02 -V 01 The voltage obtained by V is shown by the dashed double-dashed line. 02 -V 01 The voltage obtained by canceling the offset voltage from the voltage of V (after offset cancellation) is shown by a solid line. 02 -V 01 13 shows a graph with a smaller vertical scale (after offset cancellation).

[0070] Output voltage V 01 The variable amplifier circuit 140C outputs an AC voltage V C1 That is, the output voltage V 01 is V in Eq. (2). C V C1 The output voltage V 02 The variable amplifier circuit 140C outputs an AC voltage V C2That is, the output voltage V 02 is V in Eq. (2). C V C2 This is the output voltage obtained by substituting V C1 >V C2 Because V 01 <V 02 Therefore, the voltage difference is V 02 -V 01 (>0) is used. Voltage V 02 -V 01 is the output voltage V 02 to output voltage V 01 is subtracted from the voltage, V 02 -V 01 (After offset cancellation) is the voltage V 02 -V 01 Therefore, the output voltage V when the fingertip FT is not present within the detectable range of the capacitance sensor 100 (non-operation state) is 01 , V 02 This is the voltage with the value of (offset voltage) removed.

[0071] Here, as an example, when each detection electrode 111 is selected, the variable amplifier circuit 140C outputs an amplitude V C1 After outputting an AC voltage of amplitude V C2 To apply an AC voltage of V 01 is the output voltage V 02 The output voltage V 01 , V 02 is temporarily held by the holding unit 172, and the operation determination unit 171 determines the output voltage V 01 , V 02 The presence or absence of pressure is judged based on the output voltage V 01 , output voltage V 02 , V 02 -V 01 , V 02 -V 01 The graph showing (after offset cancellation) is the output voltage V obtained for the detection electrode 111 at the position pressed by the fingertip FT when the selection of each detection electrode 111 is repeated. 01 , output voltage V02 , V 02 -V 01 , V 02 -V 01 (after offset cancellation) values ​​are arranged in chronological order.

[0072] As shown in Figure 5(B), the output voltage V 01 , V 02 Although the voltage values ​​are different, they change in the same way over time. Also, as shown in Figure 5(B), the voltage V 02 -V 01 And, V 02 -V 01 (After offset cancellation) The only difference is the voltage value, but the change over time is the same.

[0073] The enlarged view of V in Figure 5(C) 02 -V 01 (after offset cancellation) rises from 0V at approximately 7 o'clock, which coincides with the time when the fingertip FT starts to press. Therefore, the output of the variable amplifier circuit 140C is set to the AC voltage V C1 and V C2 The output voltage V 01 and V 02 If the operation determination unit 171 determines whether or not a pressure has been applied by using an appropriate threshold value for the difference between these values, it is possible to accurately detect that a pressure has been applied while eliminating the influence of a change in capacitance Cf due to a pressure.

[0074] Therefore, it is possible to provide the capacitance sensor 100 that can easily detect that the cover 101 is pressed by the fingertip FT.

[0075] The detection unit 150 has an operational amplifier 152 that 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, so that the AC voltage VB input to the non-inverting input terminal can be reflected to the inverting input terminal and applied to the detection electrode 111, and it can accurately detect that the cover 101 has been pressed by the fingertip FT.

[0076] Moreover, since the output voltage V0 is expressed by the formula (1), it is possible to easily detect that the cover 101 is pressed by the fingertip FT based on the output voltage V0.

[0077] Also, AC voltage V A , AC voltage V C , and AC voltage V B The amplitude of the force is calculated by the following equation (1) when no pressure is applied by the fingertip FT: B -V A ) × Cp term and (V B -V C ) × Cs terms cancel each other out. A , V B , and V C Therefore, the dynamic range of the capacitance Cf in the formula (2) can be increased.

[0078] Even when the fingertip FT is not present (no operation state), the capacitance sensor 100 outputs an output voltage V0 according to the capacitance generated between the detection electrode 111 and the drive electrode 112 and the surrounding object.

[0079] Here, when the fingertip FT starts approaching the detection electrode 111 from a non-operation state, in order to make it easier to detect the approach of the fingertip FT, the dynamic range of the capacitance Cf may be increased. B -V A ) × Cp term and (V B -V C ) × Cs term cancels out when the AC voltage V A , AC voltage V B , AC voltage V C , the dynamic range of the capacitance Cf in equation (2) can be increased.

[0080] Therefore, the AC voltage V A , AC voltage V B , and AC voltage V C In the absence of any operation, (V B -V A ) × Cp term and (V B -VC ) × Cs terms cancel each other out. A , V B , and V C This makes it easier to detect the proximity of the fingertip FT to the cover 101 when no operation is being performed.

[0081] Furthermore, the amplifier circuit 140B applies an AC voltage V B Since the detection electrodes 111 can be reliably selected with a simple configuration, it is possible to easily detect that the cover 101 has been pressed by the fingertip FT.

[0082] In addition, the operation determination unit 171 determines whether the variable amplifier circuit 140C is an AC voltage V C The amplitude of is set to a given amplitude (e.g. V C1 ), the output of the detection unit 150 (for example, V 01 ), it is determined that the fingertip FT has come into proximity or contact with the cover 101, so that it is possible to detect proximity and contact in addition to pressing. Therefore, different functions can be assigned to contact and pressing, such as selecting the content to be displayed in a GUI (Graphic User Interface) or the like at the contacted position when contact is made, and finalizing the selected content when pressing.

[0083] In addition, the operation determination unit 171 determines whether the variable amplifier circuit 140C is an AC voltage V C The amplitude of C1 , V C2 ), the output voltages (e.g., V 01 , V 02 ), it is possible to determine whether a pressure has been applied based on multiple output voltages (e.g., V 01 , V 02 ) can be securely held, and it can be accurately detected that the cover 101 has been pressed by the fingertip FT.

[0084] In addition, in a state in which the detection unit 150 is connected to each detection electrode 111, the operation determination unit 171 detects whether the variable amplifier circuit 140C outputs an AC voltage V C The amplitude of C1 , V C2 ) are changed to a plurality of output voltages (e.g., V 01 , V 02 ), it is determined that a pressure has been applied to the position of the cover 101 corresponding to the connected detection electrode 111. For this reason, when the position of the fingertip FT with respect to the cover 101 is almost the same, AC voltages of multiple amplitudes (for example, V C1 , V C2 ) can be applied, and the capacitance Cs can be detected by applying an AC voltage (for example, V C1 , V C2 ) output voltage (for example, V C1 , V C2 ) can be used to accurately detect that the cover 101 is pressed by the fingertip FT.

[0085] Also, AC voltage V A As a driving section that applies the signal, the surface side electrode 110 adjacent to the detection electrode 111 among the surface side electrodes 110 other than the detection electrode 111 included in the plurality of surface side electrodes 110 is used as the driving electrode 112, so that the proximity, contact, and pressure of the fingertip FT to the cover 101 can be detected based on the output voltage V0 by utilizing 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 pressure of the fingertip FT to the cover 101 can be stably detected based on the output voltage V0 by using the capacitance Cp between the adjacent surface side electrodes 110.

[0086] Also, AC voltage V A , AC voltage V B , AC voltage V C About V A ≧V B >V C In addition, the AC voltage V A, AC voltage V B , AC voltage V C By using this, the output voltage V0 increases as the fingertip FT approaches, contacts, and presses, making it easier to determine the movement of the fingertip FT based on the output voltage V0.

[0087] In addition, when the capacitance sensor 100 connects the amplifier circuit 140A to the two front electrodes 110 selected as the driving electrodes 112 by the selection unit 160A, and connects the input terminal 151 to the front electrode 110 selected as the detection electrode 111 by the selection unit 160B, it can detect the proximity, contact, and pressure of the fingertip FT to 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 electrodes 111 and the driving electrodes 112.

[0088] Furthermore, since the signals for detecting proximity, contact, and pressure are centralized into the output voltage V0, the wiring connecting the multiple front electrodes 110 with the amplifier circuit 140A, the amplifier circuit 140B, the variable amplifier circuit 140C, the power supply circuit 145, and the detection unit 150 can be minimized, and the detection unit 150 can also be made smaller, making it possible to provide a capacitance sensor 100 with a simplified configuration.

[0089] In addition, since the signals for detecting proximity, contact, and pressure are centralized into the output voltage V0, the increase in the time required for the processing to detect proximity, contact, and pressure can be minimized, and the processing time for detecting proximity, contact, and pressure can be shortened.

[0090] Also, AC voltage V A , AC voltage V B , and AC voltage V C is a sine wave, the output voltage V0 can be easily calculated based on the formula (2) using the amplifier circuit 140A, the amplifier circuit 140B, the variable amplifier circuit 140C, and the power supply circuit 145. Also, based on the output voltage V0 calculated in this manner, the proximity, contact, and pressure of the fingertip FT to the cover 101 can be stably detected.

[0091] In the above, the AC voltage of a predetermined frequency output from the power supply circuit 145 is amplified by the amplifier circuit 140A, the amplifier circuit 140B, and the variable amplifier circuit 140C to generate the AC voltage V A , V B , V C1 and V C2 However, the AC voltage V A , V B , V C1 and V C2 The circuit for outputting the AC voltage V is not limited to the circuit described above. A , V B , V C1 and V C2 It is sufficient if the phases of the power supplies can be aligned and the amplitudes can be adjusted appropriately. For example, a circuit for aligning the phases of a plurality of power supplies may be provided, and then a plurality of power supply circuits may be provided.

[0092] In addition, the AC voltage V A , AC voltage V B , and AC voltage V C The AC voltage V A , AC voltage V B , and AC voltage V C may be a square wave. In this case, the power supply circuit 145 may output a square wave AC voltage instead of a sine wave AC voltage. Even if a square wave is used instead of a sine wave, the proximity, contact, and pressing of the fingertip FT to the cover 101 can be detected in the same manner based on the amplitude V0 of the output voltage V0.

[0093] In the above, a configuration using a plurality of front electrodes 110 arranged in a matrix as shown in FIG. 1 has been described. However, the plurality of front electrodes 110 included in the capacitance sensor 100 is not limited to such a configuration. The plurality of front electrodes 110 may be configured to detect the proximity, contact, and pressure of the fingertip FT to the cover 101 based on a change in capacitance between 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 may be electrodes patterned in a diamond shape in a plan view.

[0094] <Embodiment 2> 6 is a diagram showing a capacitance sensor 200 of the second embodiment. The capacitance sensor 200 includes a detection electrode 111, a driving electrode 112, an elastic dielectric 120, a shield electrode 130, an amplifier circuit 140A, an amplifier circuit 140B, a variable amplifier circuit 140C, a power circuit 145, a detection unit 150, and changeover switches 261 and 262. The changeover switches 261 and 262 are an example of a selection unit that selects one or more detection electrodes 111 from the front side electrodes 110. In FIG. 6, the detection electrode 111, the driving electrode 112, the elastic dielectric 120, and the shield electrode 130 are shown in planar configuration in the XY plane. Also, the cover 101 is omitted in FIG. 6.

[0095] In the second embodiment, a configuration will be described in which the capacitance sensor 200 includes two front side electrodes 110, one of which is used as a detection electrode 111 and the other is used as a drive electrode 112. Note that the same components as those in the capacitance sensor 100 of the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0096] The changeover switches 261 and 262 are both three-terminal type switches, and can switch the connection destination between the amplifier circuit 140A and the input terminal 151 between the detection electrode 111 and the drive electrode 112. FIG. 6 shows a state in which the changeover switches 261 and 262 connect the surface side electrode 110 on the -X direction side to the input terminal 151 as the detection electrode 111, and connect the surface side electrode 110 on the +X direction side to the amplifier circuit 140A as the drive electrode 112. However, by switching the changeover switches 261 and 262, 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, so that 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 can be used as the drive electrode 112.

[0097] If the capacitance (electrostatic capacitance) between the detection electrode 111 and the drive electrode 112 is Cp, then the following formula (2) holds, as in the capacitance sensor 100 of the first embodiment. C1 and V C2 The output voltage V 01 and V 02 If the operation determination unit 171 determines whether or not a pressure has been applied by using an appropriate threshold value for the difference between these values, it is possible to accurately detect that a pressure has been applied while eliminating the influence of a change in capacitance Cf due to a pressure.

[0098] Therefore, similarly to the capacitance sensor 100 of the first embodiment, it is possible to provide the capacitance sensor 200 that can easily detect that the cover 101 is pressed by the fingertip FT.

[0099] In addition, the operation determination unit 171 determines whether the variable amplifier circuit 140C is an AC voltage V C The amplitude of is set to a given amplitude (e.g. V C1), it is determined that the fingertip FT has approached or contacted the cover 101 based on the output of the detection unit 150, so that it is possible to detect approach and contact in addition to pressing. Therefore, different functions can be assigned to contact and pressing, such that when contact is made, the content displayed in the GUI or the like at the contacted position is selected, and when pressing is made, the selected content is confirmed.

[0100] Similarly, even 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 proximity, contact, and pressure of the fingertip FT to the detection electrode 111 can be detected based on the output voltage V0 of the output terminal 155 of the detection unit 150.

[0101] Therefore, by using one of the two front side electrodes 110 as a detection electrode 111 and the other as a drive electrode 112, the proximity, contact, and pressure of the fingertip FT to the detection electrode 111 can be detected.

[0102] The capacitance sensor 200 also includes switches 261 and 262 as a selection unit for selecting the detection electrode 111 from the front electrodes 110, and the amplifier circuit 140B applies an AC voltage V B Therefore, by adding the changeover switches 261 and 262 as a minimum circuit, one or the other of the two front electrodes 110 can be selectively set to either the detection electrode 111 or the drive electrode 112, and the proximity, contact, and pressure of the fingertip FT (detection object) to the cover 101 can be detected based on the output voltage V0.

[0103] In the second embodiment, one of the two front side electrodes 110 is used as the detection electrode 111 and the other is used as the drive electrode 112. However, when the capacitance sensor 200 includes three front side electrodes 110 arranged in the X direction, the following can be done. When three changeover switches similar to the changeover switches 261 and 262 are connected to the three front side electrodes 110 and the front side electrode 110 on the -X direction side is used as the detection electrode 111, the center front side electrode 110 in the X direction and the front side electrode 110 on the +X direction side are used as the drive electrode 112 to detect the proximity, contact, and pressure of the fingertip FT to the detection electrode 111. When the front side electrode 110 on the +X direction side is used as the detection electrode 111, the opposite can be done.

[0104] When the front side electrode 110 in the center in the X direction is used as the detection electrode 111, the front side electrodes 110 on the -X direction side and the +X direction side are used as the drive electrodes 112 to detect the proximity, contact, and pressure of the fingertip FT to the detection electrode 111. Also, it is possible to use one of the front side electrodes 110 other than the detection electrode 111 as the drive electrode 112, and use the remaining front side electrodes 110 as floating electrodes.

[0105] In addition, when the number of front side electrodes 110 is four or more, for example, a plurality of capacitance sensors 200 as shown in FIG. 6 may be provided to detect the proximity, contact, and pressure on the front side electrodes 110 selected as the detection electrodes 111.

[0106] <Embodiment 3> 7 is a diagram showing a capacitance sensor 300 of embodiment 3. The capacitance sensor 300 includes a cover 101, a substrate 102, a detection electrode 111, an elastic dielectric 120, a shield 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.

[0107] In the third embodiment, a configuration will be described in which the capacitance sensor 300 includes one front electrode 110 and is used as the detection electrode 111. Note that the same components as those in the capacitance sensor 100 of the first embodiment are given the same reference numerals and their description will be omitted.

[0108] The capacitor 370 is provided in place of the capacitance Cp between the detection electrode 111 and the two drive electrodes 112 in the first embodiment, and has a capacitance Cp3. The capacitance Cp3 is equal to the capacitance Cp in the first embodiment, as an example.

[0109] The terminal 380 is an example of a driving unit, and is coupled to the detection electrode 111 via a capacitance Cp3. The terminal 380 in this embodiment receives an AC voltage V from the amplifier circuit 140A instead of the two driving electrodes 112 in the first embodiment. A is the component to be output.

[0110] Since the capacitance Cf between the detection electrode 111 and the fingertip FT and the capacitance Cs between the detection electrode 111 and the shield electrode 130 are similar to the capacitance Cf and capacitance Cs in the first embodiment, respectively, the output voltage V0 of the output terminal 155 of the detection unit 150 can be expressed by the equation (2) as in the first embodiment.

[0111] Therefore, the output of the variable amplifier circuit 140C is set to an AC voltage V C1 and V C2 The output voltage V 01 and V 02 If the operation determination unit 171 determines whether or not a pressure has been applied by using an appropriate threshold value for the difference between these values, it is possible to accurately detect that a pressure has been applied while eliminating the influence of a change in capacitance Cf due to a pressure.

[0112] Therefore, similarly to the capacitance sensor 100 of the first embodiment, it is possible to provide the capacitance sensor 300 that can easily detect that the cover 101 is pressed by the fingertip FT.

[0113] In addition, the operation determination unit 171 determines whether the variable amplifier circuit 140C is an AC voltage V CThe amplitude of is set to a given amplitude (e.g. V C1 ), it is determined that the fingertip FT has approached or contacted the cover 101 based on the output of the detection unit 150, so that it is possible to detect approach and contact in addition to pressing. Therefore, different functions can be assigned to contact and pressing, such that when contact is made, the content displayed in the GUI or the like at the contacted position is selected, and when pressing is made, the selected content is confirmed.

[0114] In the third embodiment, the capacitance sensor 300 using one front electrode 110 as the detection electrode 111 has been described. However, if there are multiple front electrodes 110, for example, multiple capacitance sensors 300 as shown in FIG. 7 can be provided to use each front electrode 110 as a detection electrode 111 to detect proximity to, contact with, and pressure on each detection electrode 111.

[0115] The above describes an exemplary embodiment of a capacitance sensor of the present invention. However, the present invention is not limited to the specifically disclosed embodiment, and various modifications and changes are possible without departing from the scope of the claims.

[0116] This international application claims priority to Japanese patent application No. 2021-161423, filed on September 30, 2021, the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0117] 100, 200, 300 Capacitive Sensor 101 Cover 102 Substrate 110 Front electrode 111 Detection electrode 112 Drive electrode 120 Elastic Dielectrics 130 Shield electrode 140A Amplification circuit (together with the power supply circuit 145, an example of a first voltage output unit) 140B Amplification circuit (together with the power supply circuit 145, an example of a third voltage output unit) 140C variable amplifier circuit (together with the power supply circuit 145, an example of a second voltage output section) 145 Power supply circuit 150 Detector 151 Input terminal 152 Operational Amplifiers 153 Capacitor 154 Resistor 155 Output terminal 160A, 160B selection section 170 Control device 171 Operation judgment section 172 Holding part 261, 262 Changeover switch (an example of a selection section) 370 Capacitor 380 Terminals

Claims

1. one or more front electrodes including one or more detection electrodes; a cover disposed on a front side of the one or more front side electrodes; an elastic dielectric provided on the rear side of the one or more front electrodes; a shield electrode provided on a rear side of the elastic dielectric; a first voltage output unit that outputs a first AC voltage to a drive unit that is capacitively coupled to the one or more detection electrodes; a second voltage output unit that outputs a second AC voltage having the same phase as the first AC voltage to the shield electrode; a detection unit connected to the one or more detection electrodes and detecting an output corresponding to a capacitance of the one or more front electrodes; a motion determination unit that determines a motion of the detection target object in response to an output from the detection unit; Including, the second voltage output unit is capable of changing an amplitude of the second AC voltage, the operation determination unit determines that the object to be detected has pressed the cover based on a plurality of outputs of the detection unit obtained when the second voltage output unit changes the amplitude of the second AC voltage to a plurality of amplitudes, A capacitive sensor, wherein the amplitude of the first AC voltage is constant.

2. a third voltage output unit that outputs a third AC voltage having the same phase as the first AC voltage, 2. The capacitance sensor according to claim 1, wherein the detection unit includes an operational amplifier having an inverting input terminal connected to the one or more detection electrodes and a non-inverting input terminal connected to the third voltage output unit and performing a negative feedback operation.

3. The capacitance between the detection electrode and the detection object is Cf, the capacitance between the detection electrode and the drive unit is Cp, the capacitance between the detection electrode and the shield electrode is Cs, and the first AC voltage is V Ａ , the second AC voltage is V Ｃ , the third AC voltage is V Ｂ The capacitance of the capacitor connected between the output terminal and the inverting input terminal of the operational amplifier is Cq, and the output voltage of the output terminal is V ０ Then, the output voltage V ０ is expressed by the following formula (1): The capacitance sensor according to claim 2 , wherein the third AC voltage V B is greater than the second AC voltage V C . [0010]

4. The amplitudes of the first AC voltage, the second AC voltage, and the third AC voltage are expressed by the following formula (1) in a state where the object to be detected is not being pressed: (V Ｂ -V Ａ ) × Cp term, and (V Ｂ -V Ｃ ) × Cs terms cancel each other out. Ａ , V Ｂ , and V Ｃ The capacitance sensor according to claim 3 , wherein the capacitance is set to

5. A selection unit that selects the one or more detection electrodes from the one or more front side electrodes, The capacitance sensor according to claim 2 , wherein the third voltage output section outputs the third AC voltage to the one or more detection electrodes selected by the selection section.

6. 6. The capacitance sensor according to claim 1, wherein the operation determination unit determines that the object to be detected has approached or contacted the cover based on the output of the detection unit when the second voltage output unit sets the amplitude of the second AC voltage to a predetermined amplitude.

7. Further comprising a holding unit that holds an output of the detection unit; 7. The capacitance sensor according to claim 1, wherein the operation determination unit determines that the pressing has been performed based on multiple outputs of the detection unit that are respectively held by the holding unit when the second voltage output unit changes the amplitude of the second AC voltage to multiple amplitudes.

8. the one or more detection electrodes are a plurality of detection electrodes, and the one or more front side electrodes are a plurality of front side electrodes including the plurality of detection electrodes, the detection unit is connected to each of the plurality of detection electrodes in sequence, and detects an output corresponding to a capacitance of the plurality of front electrodes in a state where the detection unit is connected to each detection electrode; 8. The capacitance sensor according to claim 1, wherein the operation determination unit determines that the pressing has occurred at a position on the cover corresponding to the connected detection electrode based on multiple outputs of the detection unit obtained when the second voltage output unit changes the amplitude of the second AC voltage to multiple amplitudes for each connected detection electrode when the detection unit is connected to each detection electrode.

9. the one or more front-side electrodes are a plurality of front-side electrodes, The capacitance sensor according to claim 1 , wherein the driving section is at least one of the surface-side electrodes other than the one or more detection electrodes included in the plurality of surface-side electrodes.

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