Capacitance detection device

Abstract

Provided is a capacitance detection device that can suppress the effects of drift in capacitance value caused by environmental changes in temperature, humidity, and the like.　A capacitance detection device according to the present invention includes a sensor electrode, a shield electrode that is arranged near the sensor electrode, a first voltage output unit that outputs a first alternating-current voltage to the sensor electrode, a second voltage output unit that applies a second alternating-current voltage that has the same frequency and phase as the first alternating-current voltage but a greater amplitude than the first alternating-current voltage to the shield electrode, a detection unit that detects a self-capacitance value for the sensor electrode, an adjustment electrode that is arranged near the sensor electrode, and a voltage setting unit that outputs a third alternating-current voltage that has the same frequency and phase as the first alternating-current voltage but a smaller amplitude than the first alternating-current voltage or a third alternating-current voltage that has the same frequency as the first alternating-current voltage but the opposite phase of the first alternating-current voltage to the adjustment electrode or sets the adjustment electrode to a fixed potential.

Description

Capacitance detection device

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

[0002] Conventionally, there has been a proximity / contact sensor (capacitance detection device) that has an upper electrode (sensor electrode) and a lower electrode, and in addition, a shield electrode is arranged around the lower electrode and a ground electrode is arranged around the shield electrode, so that the capacitance value of the lower electrode can be measured without being affected by the surroundings (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2019-149207

[0004] However, in a capacitance detection device in which different voltages are applied to the sensor electrode and the shield electrode, there is no disclosure of suppressing the influence of drift in the detected capacitance value due to environmental changes such as temperature and humidity.

[0005] Therefore, an object of the present invention is to provide a capacitance detection device that can suppress the influence of temperature drift of the capacitance value.

[0006] a first voltage output unit that outputs a first AC voltage to the sensor electrode; a second voltage output unit that applies a second AC voltage to the shield electrode, the second AC voltage having the same frequency and phase as the first AC voltage and a larger amplitude than the first AC voltage; a detection unit that detects a self-capacitance value of the sensor electrode; an adjustment electrode that is disposed near the sensor electrode; and a voltage setting unit that outputs to the adjustment electrode a third AC voltage having the same frequency as the first AC voltage, the same phase as the first AC voltage, and a smaller amplitude than the first AC voltage, or a third AC voltage having the same frequency as the first AC voltage and an opposite phase to the first AC voltage, or that sets the adjustment electrode to a fixed potential.

[0007] It is possible to provide a capacitance detection device that can suppress the influence of drift in capacitance value due to environmental changes such as temperature and humidity.

[0008] 1 is a diagram illustrating a capacitance detection device according to an embodiment; FIG. 2 is a diagram illustrating a planar configuration of a portion of a sensor unit including a sensor electrode and an insulating layer; FIG. 3 is a diagram illustrating a planar configuration of a portion of a sensor unit including a shield electrode, an adjustment electrode, and an insulating layer; FIG. 4 is a diagram illustrating a cross-sectional configuration of a sensor unit 110; FIG. 5 is a diagram illustrating self-capacitance detection; FIG. 6 is a diagram illustrating absolute self-capacitance detection; FIG. 7 is a diagram illustrating absolute self-capacitance detection according to an embodiment; FIG. 8 is a diagram illustrating a modified example of an adjustment electrode;

[0009] Hereinafter, an embodiment to which the capacitance detection device of the present disclosure is applied will be described.

[0010] 1 is a diagram showing a capacitance detection device 100 according to an embodiment. The following description will be given by defining an XYZ coordinate system. For ease of explanation, the -Z direction will be referred to as the lower side or bottom, and the +Z direction will be referred to as the upper side or top, but this does not represent a universal vertical relationship. Also, viewing the XY plane will be referred to as a planar view.

[0011] The capacitance detection device 100 includes a top panel 101, a sensor unit 110, AC voltage output units 121 and 122, and a detection circuit 130. The AC voltage output unit 121 is an example of a first voltage output unit, the AC voltage output unit 122 is an example of a second voltage output unit, and the detection circuit 130 is an example of a detection unit.

[0012] The capacitance detection device 100 detects the proximity or contact of a human body, such as a hand, with a top panel 101. The upper surface of the top panel 101 is an operation surface of an input device, etc., including the capacitance detection device 100. A human body, such as a hand, is an example of an object to be detected by the capacitance detection device 100. The following describes a case where a user brings a fingertip FT close to the top panel 101. Note that, although a form in which the top panel 101 is a component of the capacitance detection device 100 will be described, the top panel 101 may also be a component of an input device that includes the capacitance detection device 100.

[0013] The sensor unit 110 has a sensor electrode (Rx) 111, a shield electrode (AS) 112, an adjustment electrode (AJ) 113, and insulating layers 115A and 115B. As an example, the sensor unit 110 is realized by a wiring board having a laminated structure in which the insulating layer 115B, the shield electrode 112, the adjustment electrode 113, the insulating layer 115A, and the sensor electrode 111 are laminated from bottom to top.

[0014] The shield electrode 112 and the adjustment electrode 113 are provided on a second surface opposite to the first surface on the +Z direction side of the insulating layer 115A. The shield electrode 112 and the adjustment electrode 113 are provided on the −Z direction side (second side) of the sensor electrode 111, opposite to the +Z direction side (first side) of the sensor electrode 111 where the fingertip FT is close to the sensor electrode 111. Because the insulating layer 115A is very thin, the shield electrode 112 and the adjustment electrode 113 are arranged close to the sensor electrode 111.

[0015] In addition to FIG. 1 , the following description will be made with reference to FIGS. 2A, 2B, and 3 . FIG. 2A is a diagram showing the planar configuration of a portion of the sensor unit 110 including the sensor electrode 111 and the insulating layer 115A. FIG. 2B is a diagram showing the planar configuration of a portion of the sensor unit 110 including the shield electrode 112, the adjustment electrode 113, and the insulating layer 115B. FIG. 2A shows six sensor electrodes 111, and FIG. 2B shows one shield electrode 112 and six adjustment electrodes 113. The sensor electrode 111 is included in a first layer of a wiring substrate that realizes the sensor unit 110. The shield electrode 112 and the adjustment electrode 113 are included in a second layer of the wiring substrate that realizes the sensor unit 110. Therefore, the shield electrode 112 and the adjustment electrode 113 are provided on the same layer, different from the sensor electrode 111. Note that the insulating layer 115A shown in FIG. 2A and the insulating layer 115B shown in FIG. 2B have the same size (length in the X direction and length in the Y direction) in a plan view.

[0016] Fig. 3 is a diagram showing the cross-sectional configuration of the sensor unit 110. The cross section in Fig. 3 corresponds to the cross section taken along the line A-A in Fig. 2A and the cross section taken along the line B-B in Fig. 2B. The portion shown in Fig. 1 corresponds to a portion of the cross section in Fig. 3 that includes one shield electrode 112 and one adjustment electrode 113.

[0017] The sensor unit 110 includes, for example, six sensor electrodes 111 (see FIG. 2A), one shield electrode 112 (see FIG. 2B), and six adjustment electrodes 113 (see FIG. 2B).

[0018] 2A , six sensor electrodes 111 are arranged in a matrix of two rows and three columns, for example. Wiring 114A is connected to each sensor electrode 111. The sensor electrodes 111 are electrodes that detect the electrostatic capacitance between the fingertip FT using a self-capacitance method, and are made of a conductive material such as an ITO (indium tin oxide) film, zinc oxide, tin oxide, or titanium oxide, for example. When the sensor electrodes 111 are ITO films, the insulating layer 115A may be a transparent substrate.

[0019] The sensor electrode 111 is connected to the AC voltage output unit 121 and the detection circuit 130 via wiring 114A (see FIG. 2A ). Although FIG. 1 shows one sensor electrode 111, in reality, there are six sensor electrodes 111, as shown in FIG. 2A . For this reason, a selection unit such as a multiplexer may be provided between the six sensor electrodes 111 and the AC voltage output unit 121 and between the six sensor electrodes 111 and the detection circuit 130 to connect them in a time-division manner. Each sensor electrode 111 is connected to the detection circuit 130 when detecting the capacitance between itself and the fingertip FT using a self-capacitance method, and is also connected to the AC voltage output unit 121 to apply an AC voltage. The AC voltage applied to each sensor electrode 111 from the AC voltage output unit 121 is an example of a first AC voltage.

[0020] 1 , the shield electrode 112 is connected to the AC voltage output unit 122, and an AC voltage is applied to each sensor electrode 111 when the sensor electrode 111 detects the capacitance between itself and the fingertip FT using a self-capacitance method. The AC voltage applied to the shield electrode 112 from the AC voltage output unit 122 is an example of a second AC voltage. The shield electrode 112 is made of a conductive material such as an ITO film, zinc oxide, tin oxide, or titanium oxide. When the sensor electrode 111 is made of an ITO film, the shield electrode 112 and the adjustment electrode 113 may also be made of an ITO film, and the insulating layers 115A and 115B may be transparent substrates.

[0021] As an example, the AC voltage applied from the AC voltage output unit 121 to each sensor electrode 111 and the AC voltage applied from the AC voltage output unit 122 to the shield electrode 112 have the same frequency and phase. In this case, the amplitude Vas of the AC voltage applied from the AC voltage output unit 122 to the shield electrode 112 is larger than the amplitude Vrx of the AC voltage applied from the AC voltage output unit 121 to each sensor electrode 111. Note that since the AC voltage applied from the AC voltage output unit 121 to each sensor electrode 111 and the AC voltage applied from the AC voltage output unit 122 to the shield electrode 112 have the same frequency and phase, it is also possible to use a single AC voltage output unit instead of the AC voltage output units 121 and 122, and to provide a variable amplifier between the AC voltage output unit and the sensor electrode 111, and also to provide a variable amplifier between the AC voltage output unit and the shield electrode 112, and to adjust the amplification factor so that the amplitude Vas is larger than the amplitude Vrx.

[0022] In a plan view, the rectangular outer edge of the shield electrode 112 shown in FIG. 2B includes the rectangular outer edges of the six sensor electrodes 111 shown in FIG. 2A . A first region 111A in which each sensor electrode 111 is provided is located inside a second region 112A in which the shield electrode 112 is provided. For ease of understanding, the first region 111A is shown outside the outer edge of the sensor electrode 111, but the outer edge of the first region 111A is equal to the outer edge of the sensor electrode 111. Similarly, the second region 112A is shown outside the outer edge of the shield electrode 112, but the outer edge of the second region 112A is equal to the outer edge of the shield electrode 112. Because six adjustment electrodes 113 are arranged inside the rectangular outer edge of the shield electrode 112, the shield electrode 112 has a non-formed portion 112B patterned to avoid the six adjustment electrodes 113.

[0023] As shown in FIG. 1 , the adjustment electrode 113 is grounded via wiring 114B. Wiring 114B is an example of a voltage setting unit that sets the adjustment electrode 113 to a fixed ground potential (ground potential). In practice, six adjustment electrodes 113 are provided as shown in FIG. 2B , and all of the adjustment electrodes 113 are grounded via wiring 114B. The adjustment electrodes 113 are made of a conductive material such as an ITO film, zinc oxide, tin oxide, or titanium oxide, for example. When the sensor electrode 111 is an ITO film, the adjustment electrode 113 and the shield electrode 112 may also be made of an ITO film, and the insulating layers 115A and 115B may be transparent substrates.

[0024] As shown in FIG. 2B , the adjustment electrodes 113 are arranged inside the rectangular outer edge of the shield electrode 112 and within the outer edges of the sensor electrodes 111 in a plan view. In a plan view, the adjustment electrodes 113 are smaller than the sensor electrodes 111. In a plan view, six third regions 113A, in which six adjustment electrodes 113 are provided, are located inside six first regions 111A, in which six sensor electrodes 111 are provided. Here, for ease of understanding, the third regions 113A are shown outside the outer edges of the adjustment electrodes 113, but the outer edges of the third regions 113A are the same as the outer edges of the adjustment electrodes 113. Furthermore, because all sensor electrodes 111 are arranged inside the rectangular outer edge of the shield electrode 112 in a plan view, all third regions 113A, in which all adjustment electrodes 113 are arranged, are located inside the second region in which the shield electrode 112 is arranged. The function of the adjustment electrodes 113 will be described in detail later.

[0025] The AC voltage output units 121 and 122 are AC voltage sources that output AC voltages to be applied to the sensor electrode 111 and the shield electrode 112, respectively. The AC voltage output unit 121 applies an AC voltage of amplitude Vrx to the sensor electrode 111 selected by a multiplexer or the like (not shown) in a time-division manner. The AC voltage output unit 122 applies an AC voltage of amplitude Vas to the shield electrode 112. The amplitude Vas is larger than the amplitude Vrx. In other words, an AC voltage with a larger amplitude than that of the sensor electrode 111 is applied to the shield electrode 112.

[0026] The detection circuit 130 detects the self-capacitance value of the connected sensor electrode 111. Specifically, the detection circuit 130 detects the capacitance between each sensor electrode 111 and the fingertip FT in a time-division manner. The detection circuit 130 detects the XY and Z coordinates of the fingertip FT when the fingertip FT is in proximity to the top panel 101, and can also detect the XY coordinates of the fingertip FT when the fingertip FT is in contact with the top panel 101. Note that proximity refers to a state in which the fingertip FT is not in contact with the operation surface of the top panel 101, but it is possible to determine that the fingertip FT is approaching the operation surface based on the capacitance between each sensor electrode 111 and the fingertip FT.

[0027] <Capacitance detection method> Here, the capacitance detection method will be described using Figures 4A, 4B, and 4C. The contents shown in Figures 4A, 4B, and 4C are not of the prior art, but are diagrams explaining the principles of each detection method.

[0028] FIG. 4A is a diagram illustrating a self-capacitance capacitance detection method (self-capacitance detection). FIG. 4A is a diagram illustrating a state in which the capacitance of the fingertip FT is detected by the self-capacitance method using only the sensor electrode Rx, without using a shield electrode. This is equivalent to a capacitor Crf with a coupling capacitance Crf between the fingertip FT and the sensor electrode Rx, and a capacitor Crg with a coupling capacitance Crg between the sensor electrode Rx and ground GND. When the position of the fingertip FT relative to the sensor electrode Rx changes, the coupling capacitance Crf changes. The main purpose of the self-capacitance detection sensor is to detect this capacitance Crf as a numerical value and measure the positional relationship between the sensor electrode Rx and the fingertip FT.

[0029] When an AC voltage of amplitude Vrx is applied to the sensor electrode Rx and the potential of the sensor electrode Rx is Vrx, a positive charge is generated in the electrode of the capacitor Crg on the sensor electrode Rx side and a negative charge is generated in the electrode on the ground GND side. At this time, a negative charge is generated in the electrode of the capacitor Crf on the fingertip FT side and a positive charge is generated in the electrode on the sensor electrode Rx side.

[0030] 4A detects a value proportional to the charge generated on the sensor electrode Rx side, i.e., a value proportional to Crf + Crg. Furthermore, the capacitance of the capacitor Crg is largely accounted for by base capacitance, such as the capacitance between metals in the wiring board and the capacitance between electrodes on the touch panel, and because drift occurs in the base capacitance due to environmental changes, it is not easy to accurately detect the capacitance Crf between the fingertip FT and the sensor electrode Rx.

[0031] 4B is a diagram illustrating an absolute self-capacitance capacitance detection method (absolute self-capacitance detection). Fig. 4B is a diagram illustrating a state in which the capacitance of the fingertip FT is detected by the absolute self-capacitance method using the sensor electrode Rx and the shield electrode AS. This is equivalent to a capacitor Crf with a coupling capacitance Crf being present between the fingertip FT and the sensor electrode Rx, and a capacitor Crs with a coupling capacitance Crs being present between the sensor electrode Rx and the shield electrode AS. The frequency, amplitude Vrx, and phase of the AC voltage applied to the sensor electrode Rx are equal to the frequency, amplitude Vas, and phase of the AC voltage applied to the shield electrode AS, respectively.

[0032] When the frequency, amplitude Vrx, and phase of the AC voltage applied to the sensor electrode Rx are equal to the frequency, amplitude Vas, and phase of the AC voltage applied to the shield electrode AS, no charge is generated in the capacitor Crs, thereby eliminating the influence of the ground GND and enabling accurate detection of the capacitance between the fingertip FT and the sensor electrode Rx.

[0033] 4C is a diagram illustrating an absolute self-capacitance type capacitance detection method (absolute self-capacitance detection). The absolute self-capacitance detection shown in Fig. 4C differs from the absolute self-capacitance detection shown in Fig. 4B in that the frequency and phase of the AC voltage applied to the sensor electrode Rx are equal to the frequency and phase of the AC voltage applied to the shield electrode AS, but the amplitude Vas of the AC voltage applied to the shield electrode AS is greater than the amplitude Vrx of the AC voltage applied to the sensor electrode Rx.

[0034] Because the amplitude Vas of the AC voltage applied to the shield electrode AS is different from the amplitude Vrx of the AC voltage applied to the sensor electrode Rx, positive and negative charges are generated on the two electrodes of the capacitor Crs. The presence of positive and negative charges on the two electrodes of the capacitor Crs in this way affects the position detection of the fingertip FT, although the effect is less than that of the self-capacitance detection shown in FIG. 4A, and slight drift occurs due to environmental changes.

[0035] The capacitance detection device 100 of the embodiment suppresses drift due to environmental changes on the premise that the amplitude Vas of the AC voltage applied to the shield electrode 112 is different from the amplitude Vrx of the AC voltage applied to the sensor electrode 111. Here, explanation will be given using FIG. 5, which adds + and - signs to the charge in FIG. 1. FIG. 5 is a diagram for explaining absolute self-capacitance detection of the embodiment.

[0036] 5 , in the capacitance detection device 100 including the adjustment electrode (AJ) 113, the amplitude of the AC voltage applied to the sensor electrode (Rx) 111 is Vrx, the amplitude of the AC voltage applied to the shield electrode (AS) 112 is Va, the fixed potential of the adjustment electrode (AJ) 113 is Va, the coupling capacitance between the sensor electrode 111 and the shield electrode 112 is Crs, and the coupling capacitance between the sensor electrode 111 and the adjustment electrode 113 is Cra. In the following description, the capacitor of the coupling capacitance Crs is referred to as capacitor Crs, and the capacitor of the coupling capacitance Cra is referred to as capacitor Cra. Note that the fixed potential of the adjustment electrode 113 will be described as Va, but here Va = 0 V.

[0037] Because the amplitude Vas of the AC voltage applied to the shield electrode 112 is larger than the amplitude Vrx of the AC voltage applied to the sensor electrode 111, a positive charge is generated in the electrode of capacitor Crs on the shield electrode 112 side (the lower electrode), and a negative charge is generated in the electrode of capacitor Crs on the sensor electrode 111 side (the upper electrode). Conversely, because the amplitude (0 V because it is GND) of the AC voltage applied to the adjustment electrode 113 is smaller than the AC voltage Vrx applied to the sensor electrode 111, a positive charge is generated in the electrode of capacitor Cra on the sensor electrode 111 side (the upper electrode), and a negative charge is generated in the electrode of capacitor Cra on the adjustment electrode 113 side (the lower electrode). Furthermore, a positive charge is generated in the electrode of capacitor Crf on the sensor electrode Rx 111 side (the lower electrode), and a negative charge is generated in the electrode of capacitor Crf on the fingertip FT side (the upper electrode).

[0038] If the charges of capacitors Crs and Cra are canceled out, it becomes possible to detect a value proportional to only the charge (capacitance) of capacitor Crf. To do this, the negative charge on the electrode (upper electrode) of capacitor Crs on the sensor electrode 111 side and the positive charge on the electrode (upper electrode) of capacitor Cra on the sensor electrode 111 side must be added together to become zero, so the following equation (1) must be satisfied.

[0039]

[0040] If equation (1) is satisfied, the charges of the capacitors Crs and Cra can be canceled out, and therefore, no charge can be generated between the sensor electrode 111 and the shield electrode 112 and between the sensor electrode 111 and the adjustment electrode 113. This is similar to the state in FIG. 4B where no charge is generated in the capacitor Crs.

[0041] Furthermore, even if the condition of equation (1) that prevents charge from being generated between the sensor electrode 111 and the shield electrode 112 and the adjustment electrode 113 is not completely satisfied, the effect of canceling out the charges of capacitors Crs and Cra can be obtained by using a value close to the value of Cra that satisfies equation (1).

[0042] Regarding the coupling capacitance Cra, having the coupling capacitance Cra between the sensor electrode 111 and the adjustment electrode 113 determined based on the relational expression (1) means setting it to a value slightly deviated from the value obtained from expression (1).

[0043] As an example, when Vrx = 0.95 Vas, Crs:Cra = 0.95 × Vas: 0.05 × Vas, resulting in a Crs:Cra = 19:1. The coupling capacitance Cra that satisfies this ratio can be calculated from equation (1) and used to design the sensor electrode 111, shield electrode 112, and adjustment electrode 113. Because the capacitors Crs and Cra are present on a single wiring board and the inter-electrode distance is equal, the relationship Crs:Cra = 19:1 can be easily achieved by the area ratio of the capacitors Crs and Cra.

[0044] Furthermore, as described above, setting the value slightly shifted from the value obtained from equation (1) means, for example, reducing the proportion of Cra in the ratio Crs:Cra = 19:1 obtained from equation (1) to less than 1, which is, as an example, shifting the area ratio.

[0045] <Effects> As described above, the capacitance detection device 100 includes the sensor electrode 111, the shield electrode 112 arranged in proximity to the sensor electrode 111, the AC voltage output unit 121 that outputs a first AC voltage Vrx to the sensor electrode 111, the AC voltage output unit 122 that applies a second AC voltage Vas to the shield electrode 112. The second AC voltage Vas has the same frequency and phase as the first AC voltage Vrx and a larger amplitude than the first AC voltage Vrx, the detection circuit 130 that detects the self-capacitance value of the sensor electrode 111, the adjustment electrode 113 arranged in proximity to the sensor electrode 111, and a voltage setting unit that sets the adjustment electrode 113 to a fixed potential Va.

[0046] Under the assumption that the amplitude Vas of the AC voltage applied to the shield electrode 112 is larger than the amplitude Vrx of the AC voltage applied to the sensor electrode 111, an adjustment electrode 113 is provided that is capacitively coupled to the sensor electrode 111 and is set to a fixed potential (here, ground potential), thereby suppressing the influence of drift in the capacitance value between the sensor electrode 111 and the shield electrode 112 and adjustment electrode 113 due to environmental changes such as temperature and humidity.

[0047] Therefore, it is possible to provide a capacitance detection device 100 that can suppress the influence of drift in capacitance value due to environmental changes such as temperature and humidity.

[0048] Furthermore, if the amplitude of the first AC voltage is Vrx, the amplitude of the second AC voltage is Vas, the fixed potential is Va, the coupling capacitance between the sensor electrode 111 and the shield electrode 112 is Crs, and the coupling capacitance between the sensor electrode 111 and the adjustment electrode 113 is Cra, then the coupling capacitance Cra between the sensor electrode 111 and the adjustment electrode 113 is determined based on the relational expression in equation (1). In order to cancel out the charges of the capacitors Crs and Cra, the coupling capacitance Cra between the sensor electrode 111 and the adjustment electrode 113 is adjusted to satisfy the condition in equation (1), thereby making it possible to provide a capacitance detection device 100 that can more reliably suppress the effects of capacitance drift due to environmental changes such as temperature and humidity.

[0049] Furthermore, since the fixed potential Va is the ground potential (Va = 0 V), the adjustment electrode 113 can be easily set to the fixed potential Va, and a capacitance detection device 100 can be provided with a simple configuration that can suppress the effects of drift in capacitance value due to environmental changes such as temperature and humidity.

[0050] Furthermore, the sensor electrode 111 is provided on a first surface (the surface on the +Z direction side) of the insulating layer 115A, and the shield electrode 112 and the adjustment electrode 113 are provided on a second surface (the surface on the −Z direction side) of the insulating layer 115A opposite the first surface (the surface on the +Z direction side). The first surface (the surface on the +Z direction side) of the insulating layer 115A is located on the side from which the fingertip FT approaches the sensor electrode 111. Even if there is a ground potential component or the like that is maintained at ground potential in the −Z direction relative to the shield electrode 112, the effect of the ground potential component or the like on the detection of the fingertip FT by the sensor electrode 111 can be effectively suppressed, and the capacitance detection device 100 can be provided that can more reliably and easily suppress the effect of drift in capacitance value due to environmental changes such as temperature and humidity.

[0051] Furthermore, the sensor electrode 111, the shield electrode 112, and the adjustment electrode 113 are provided on a wiring substrate having a laminated structure, and the shield electrode 112 and the adjustment electrode 113 are provided on the same layer, different from the sensor electrode 111. This allows the inter-electrode distance between the shield electrode 112 and the sensor electrode 111 to be equal to the inter-electrode distance between the adjustment electrode 113 and the sensor electrode 111, making it easier to set the condition of equation (1). This makes it possible to provide a capacitance detection device 100 that can more reliably and easily suppress the effects of capacitance drift due to environmental changes such as temperature and humidity. Simply adding a capacitor based on the shield electrode 112 and the adjustment electrode 113 could involve providing, for example, a chip capacitor outside the wiring substrate. However, in such a case, the wiring substrate and the chip capacitor have different characteristics, such as changes in dielectric constant due to environmental changes such as temperature and humidity, making it difficult to adjust using equation (1). In contrast, if the sensor electrode 111, the shield electrode 112, and the adjustment electrode 113 are provided on the same wiring board, the effects of drift in the capacitance value due to environmental changes such as temperature and humidity will be uniform, making it possible to provide a capacitance detection device 100 that can be more reliably and easily suppressed.

[0052] Furthermore, since the sensor electrode 111 and the shield electrode 112 are arranged opposite each other, and the sensor electrode 111 and the adjustment electrode 113 are arranged opposite each other, the conditions of equation (1) can be reliably set, and a capacitance detection device 100 can be provided that can more reliably and easily suppress the effects of drift in capacitance value due to environmental changes such as temperature and humidity.

[0053] Furthermore, in a planar view, the first region 111A in which the sensor electrode 111 is provided is located inside the second region 112A in which the shield electrode 112 is provided, and in a planar view, the third region 113A in which the adjustment electrode 113 is provided is located inside the first region 111A and the second region 112A. Therefore, it is possible to reliably set the condition of equation (1), and it is possible to provide a capacitance detection device 100 that can more reliably and easily suppress the effects of drift in capacitance value due to environmental changes such as temperature and humidity.

[0054] Furthermore, since the shield electrode 112 is provided on the second side of the sensor electrode 111, opposite the first side where the fingertip FT is in proximity to the sensor electrode 111, even if a ground potential component or the like that is maintained at ground potential is present in the −Z direction relative to the shield electrode 112, the influence of the ground potential component or the like on the detection of the fingertip FT by the sensor electrode 111 can be effectively suppressed, thereby providing a capacitance detection device 100 that can more reliably and easily suppress the influence of drift in capacitance value due to environmental changes such as temperature and humidity. Furthermore, since the shield electrode 112 and the adjustment electrode 113 are provided on the second side of the sensor electrode 111, opposite the first side where the fingertip FT is in proximity to the sensor electrode 111, the shield electrode 112 and the adjustment electrode 113 can be positioned in a location that is not visible to the user. In particular, by placing the adjustment electrode 113 on the back side of the sensor electrode 111, an increase in coupling capacitance between the fingertip FT and the adjustment electrode 113 as the fingertip FT approaches can be suppressed. This also makes it possible to provide the capacitance detection device 100 that can more reliably and easily suppress the influence of drift in capacitance value due to environmental changes such as temperature and humidity.

[0055] Although the above describes a configuration in which the potential of the adjustment electrode 113 is set to a fixed potential, an AC voltage Va having a smaller amplitude than the amplitude Vrx of the AC voltage applied to the sensor electrode 111 and the same frequency and phase as the AC voltage applied to the sensor electrode 111 may also be applied to the adjustment electrode 113. The AC voltage Va applied to the adjustment electrode 113 in this manner is an example of a third AC voltage. The third AC voltage may be output from an AC voltage output unit (an example of a voltage setting unit) similar to the AC voltage output units 121 and 122. Applying an AC voltage having a smaller amplitude than the amplitude Vrx of the AC voltage applied to the sensor electrode 111 can generate a charge distribution similar to that shown in FIG. 5 in the sensor electrode 111, the shield electrode 112, and the adjustment electrode 113. Therefore, by adjusting the coupling capacitance Cra between the sensor electrode 111 and the adjustment electrode 113 so as to satisfy the following equation (2), which is the same as equation (1), it is possible to provide a capacitance detection device 100 that can more reliably suppress the influence of capacitance drift due to environmental changes such as temperature and humidity.

[0056]

[0057] Furthermore, if the amplitude of the first AC voltage is Vrx, the amplitude of the second AC voltage is Va, the amplitude of the third AC voltage that is in phase with the first AC voltage is Va, the coupling capacitance between the sensor electrode 111 and the shield electrode 112 is Crs, and the coupling capacitance between the sensor electrode 111 and the adjustment electrode 113 is Cra, then the coupling capacitance Cra between the sensor electrode 111 and the adjustment electrode 113 is determined based on the relational expression in equation (2). In order to cancel out the charges of the capacitors Crs and Cra, the coupling capacitance Cra between the sensor electrode 111 and the adjustment electrode 113 is adjusted to satisfy the condition in equation (2), thereby making it possible to provide a capacitance detection device 100 that can more reliably suppress the effects of capacitance drift due to environmental changes such as temperature and humidity.

[0058] Alternatively, an AC voltage having the same frequency as the AC voltage applied to the sensor electrode 111 but of opposite phase to the AC voltage applied to the sensor electrode 111 may be applied to the adjustment electrode 113. Such an opposite-phase AC voltage is also an example of the third AC voltage. When an opposite-phase AC voltage is applied to the adjustment electrode 113 as the third AC voltage, the amplitude of the third AC voltage does not need to be smaller than the amplitude Vrx of the AC voltage, and the amplitude of the third AC voltage may be any magnitude. The third AC voltage may be output from an AC voltage output unit (an example of a voltage setting unit) similar to the AC voltage output units 121 and 122. In the case of the opposite phase, the coupling capacitance Cra between the sensor electrode 111 and the adjustment electrode 113 may be adjusted to satisfy the following equation (3), which is a modification of equation (2).

[0059]

[0060] By applying an AC voltage of opposite phase to the adjustment electrode 113, when the charge distribution is as shown in Figure 5, the charge can be further offset by the capacitor Cra compared to when the adjustment electrode 113 is at ground potential, and it is possible to provide a capacitance detection device 100 that can more effectively and reliably suppress the effects of drift in the capacitance value due to environmental changes such as temperature and humidity.

[0061] Furthermore, if the amplitude of the first AC voltage is Vrx, the amplitude of the second AC voltage is Va, the amplitude of the third AC voltage that is opposite in phase to the first AC voltage is Va, the coupling capacitance between the sensor electrode 111 and the shield electrode 112 is Crs, and the coupling capacitance between the sensor electrode 111 and the adjustment electrode 113 is Cra, then the coupling capacitance Cra between the sensor electrode 111 and the adjustment electrode 113 is determined based on the relational expression shown in the following equation (3). In order to cancel out the charges of the capacitors Crs and Cra, the coupling capacitance Cra between the sensor electrode 111 and the adjustment electrode 113 is adjusted to satisfy the condition of equation (2), thereby making it possible to provide a capacitance detection device 100 that can more reliably suppress the effects of capacitance drift due to environmental changes such as temperature and humidity.

[0062] Although the above description has been given of a configuration in which only the sensor electrode 111 is provided on the upper surface of the insulating layer 115A, a shield electrode 112 may be provided surrounding the sensor electrode 111 on the upper surface of the insulating layer 115A, similar to the shield electrode 112 shown in Fig. 2B . By providing the shield electrode 112 around the sensor electrode 111, the coupling capacitance with surrounding metal members at ground potential is reduced, and it is possible to provide a capacitance detection device 100 that can more reliably suppress the influence of capacitance value drift due to environmental changes such as temperature and humidity.

[0063] <Modification of Adjustment Electrode 113> Fig. 6 is a diagram showing a modification of the adjustment electrode 113. Like Fig. 2B, Fig. 6 shows a planar configuration of a portion of the sensor unit 110 including the shield electrode 112, the adjustment electrode 113, and the insulating layer 115B.

[0064] 6, the adjustment electrodes 113 may be a plurality of stripe-shaped electrodes extending along the X-axis. In Fig. 6, the ends of seven adjustment electrodes 113 arranged in the Y direction on the +X-direction side are connected by wiring 114B extending in the Y direction.

[0065] In such an adjustment electrode 113, if the ratio of the width W1 of the shield electrode 112 between the adjustment electrodes 113 to the width W2 of the adjustment electrode 113 in the Y direction is set to 19:1, the ratio Crs:Cra = 19:1 can be easily and accurately achieved.

[0066] The above describes an exemplary embodiment of a capacitance detection device of the present disclosure, but the present disclosure is not limited to the specifically disclosed embodiment, and various modifications and variations are possible without departing from the scope of the claims.

[0067] This international application claims priority based on Japanese Patent Application No. 2022-080013, filed on May 16, 2022, the entire contents of which are incorporated herein by reference.

[0068] REFERENCE SIGNS LIST 100 Capacitance detection device 101 Top panel 110 Sensor section 111 Sensor electrode 111A First region 112 Shield electrode 112A Second region 113 Adjustment electrode 113A Third region 115A, 115B Insulating layer 121, 122 AC voltage output section 130 Detection circuit

Claims

1. A sensor electrode; a shield electrode disposed adjacent to the sensor electrode; a first voltage output unit that outputs a first AC voltage to the sensor electrode; a second voltage output unit that applies a second AC voltage having the same frequency and phase as the first AC voltage and an amplitude larger than that of the first AC voltage to the shield electrode; A detection unit that detects a self-capacitance value of the sensor electrode; an adjustment electrode disposed adjacent to the sensor electrode; a voltage setting unit that outputs to the adjustment electrode a third AC voltage having the same frequency as the first AC voltage, the same phase as the first AC voltage, and an amplitude smaller than that of the first AC voltage, or a third AC voltage having the same frequency as the first AC voltage and an opposite phase to that of the first AC voltage, or that sets the adjustment electrode to a fixed potential; A capacitance detection device comprising:

2. 2. The capacitance detection device according to claim 1, wherein the coupling capacitance Cra between the sensor electrode and the adjustment electrode is determined based on the following relational expression (1), where the amplitude of the first AC voltage is Vrx, the amplitude of the second AC voltage is Vas, the fixed potential is Va, the coupling capacitance between the sensor electrode and the shield electrode is Crs, and the coupling capacitance between the sensor electrode and the adjustment electrode is Cra. [0010]

3. The capacitance detection device according to claim 2 , wherein the fixed potential is a ground potential.

4. 2. The capacitance detection device according to claim 1, wherein the amplitude of the first AC voltage is Vrx, the amplitude of the second AC voltage is Vas, the amplitude of the third AC voltage having the same phase as the first AC voltage is Va, the coupling capacitance between the sensor electrode and the shield electrode is Crs, and the coupling capacitance between the sensor electrode and the adjustment electrode is Cra. The capacitance detection device according to claim 1, wherein the coupling capacitance Cra between the sensor electrode and the adjustment electrode is determined based on the following relational expression (2). [0025]

5. 2. The capacitance detection device according to claim 1, wherein the amplitude of the first AC voltage is Vrx, the amplitude of the second AC voltage is Vas, the amplitude of the third AC voltage having an opposite phase to the first AC voltage is Va, the coupling capacitance between the sensor electrode and the shield electrode is Crs, and the coupling capacitance between the sensor electrode and the adjustment electrode is Cra, wherein the coupling capacitance Cra between the sensor electrode and the adjustment electrode is determined based on the following relational expression (3). [0030]

6. The sensor electrode is provided on a first surface of an insulating layer, The capacitance detection device according to claim 1 , wherein the shield electrode and the adjustment electrode are provided on a second surface of the insulating layer opposite to the first surface.

7. 6. The capacitance detection device according to claim 1, wherein the sensor electrode, the shield electrode, and the adjustment electrode are provided on a wiring substrate having a laminated structure, and the shield electrode and the adjustment electrode are provided in the same layer different from the sensor electrode.

8. 6. The capacitance detection device according to claim 1, wherein the sensor electrode and the shield electrode are disposed opposite to each other, and the sensor electrode and the adjustment electrode are disposed opposite to each other.

9. In a plan view, a first region in which the sensor electrode is provided is located inside a second region in which the shield electrode is provided, The capacitance detection device according to claim 1 , wherein a third region in which the adjustment electrode is provided is located inside the first region and the second region in a plan view.

10. 6. The capacitance detection device according to claim 1, wherein the shield electrode and the adjustment electrode are provided on a second side of the sensor electrode opposite a first side where an object is close to the sensor electrode.

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