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

Technical Field

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

Background Art

[0002] Conventionally, in addition to an upper electrode (sensor electrode) and a lower electrode, a shield electrode is disposed around the lower electrode, and a ground electrode is disposed around the shield electrode, so that a proximity / contact sensor (capacitance detection device) capable of measuring the capacitance value of the lower electrode without being affected by the surroundings is available (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a capacitance detection device that applies different voltages to a sensor electrode and a shield electrode, it is not disclosed to suppress the influence of drift due to environmental changes such as temperature and humidity of the detected capacitance value.

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

Means for Solving the Problems

[0006] The capacitance detection device according to an embodiment of the present disclosure includes a sensor electrode, a shield electrode disposed close to the sensor electrode, a first voltage output unit that outputs a first alternating voltage to the sensor electrode, a second voltage output unit that applies a second alternating voltage having the same frequency and phase as the first alternating voltage and an amplitude larger than that of the first alternating voltage to the shield electrode, a detection unit that detects a self-capacitance value of the sensor electrode, an adjustment electrode disposed close to the sensor electrode, and a voltage setting unit that outputs a third alternating voltage having the same frequency as the first alternating voltage, the same phase as the first alternating voltage, and an amplitude smaller than the amplitude of the first alternating voltage, or a third alternating voltage having the same frequency as the first alternating voltage and a phase opposite to that of the first alternating voltage, to the adjustment electrode, or sets the adjustment electrode to a fixed potential.

Advantages of the Invention

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

Brief Description of the Drawings

[0008]

Figure 1

Figure 2A

Figure 2B

Figure 3

Figure 4A

Figure 4B

Figure 4C

Figure 5

Figure 6

Embodiment for Carrying Out the Invention

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

[0010] <Embodiment> FIG. 1 is a diagram showing a capacitance detection device 100 according to an embodiment. Hereinafter, an explanation will be given by defining an XYZ coordinate system. For convenience of explanation, the -Z direction side is referred to as the lower side or bottom, and the +Z direction side is referred to as the upper side or top, but this does not represent a universal up and down relationship. Also, viewing the XY plane is referred to as a plan 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 to the top panel 101. The upper surface of the top panel 101 is an operation surface of an input device 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. Hereinafter, the case where the user brings the fingertip FT close to the top panel 101 will be described. Here, a form in which the top panel 101 is a component of the capacitance detection device 100 will be described, but the top panel 101 may be a component of an input device including the capacitance detection device 100.

[0013] The sensor unit 110 has sensor electrodes (Rx) 111, a shield electrode (AS) 112, adjustment electrodes (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 and the adjustment electrode 113, the insulating layer 115A, and the sensor electrode 111 are laminated from the lower side to the upper side.

[0014] The shield electrode 112 and the adjustment electrode 113 are provided on the second surface of the insulating layer 115A, which is opposite to the first surface on the +Z direction side. The shield electrode 112 and the adjustment electrode 113 are provided on the -Z direction side (the second side), which is opposite to the +Z direction side (the first side) of the sensor electrode 111 where the fingertip FT approaches the sensor electrode 111. Since 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, hereinafter, in addition to FIG. 1, FIGS. 2A, 2B, and 3 will be used for explanation. FIG. 2A is a diagram showing a planar configuration of a portion including the sensor electrode 111 and the insulating layer 115A in the sensor unit 110. FIG. 2B is a diagram showing a planar configuration of a portion including the shield electrode 112, the adjustment electrode 113, and the insulating layer 115B in the sensor unit 110. Six sensor electrodes 111 are shown in FIG. 2A, and one shield electrode 112 and six adjustment electrodes 113 are shown in FIG. 2B. The sensor electrode 111 is included in the first layer of the wiring board that realizes the sensor unit 110. The shield electrode 112 and the adjustment electrode 113 are included in the second layer of the wiring board that realizes the sensor unit 110. Therefore, the shield electrode 112 and the adjustment electrode 113 are provided in the same layer different from the sensor electrode 111. Note that the sizes (the length in the X direction and the length in the Y direction) in the plan view of the insulating layer 115A shown in FIG. 2A and the insulating layer 115B shown in FIG. 2B are equal.

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

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

[0018] As shown in FIG. 2A, six sensor electrodes 111 are arranged in a matrix of two rows by three columns as an example. A wiring 114A is connected to each sensor electrode 111. The sensor electrode 111 is an electrode that self-capacitively detects the capacitance between the fingertip FT, and is made of a conductive material such as an ITO (Indium Tin Oxide) film, zinc oxide, tin oxide, titanium oxide, etc. as an example. When the sensor electrode 111 is an ITO film, the insulating layer 115A may be a transparent substrate.

[0019] The sensor electrode 111 is connected to an AC voltage output unit 121 and a detection circuit 130 via a wiring 114A (see FIG. 2A). Although one sensor electrode 111 is shown in FIG. 1, actually there are six sensor electrodes 111 as shown in FIG. 2A. Therefore, for example, a selection unit such as a multiplexer may be provided between the six sensor electrodes 111 and one AC voltage output unit 121 and between the six sensor electrodes 111 and one detection circuit 130 and connected in a time-division manner. Each sensor electrode 111 is connected to the detection circuit 130 when self-capacitively detecting the capacitance between the fingertip FT, and is connected to the AC voltage output unit 121 to which an AC voltage is applied. The AC voltage applied from the AC voltage output unit 121 to each sensor electrode 111 is an example of a first AC voltage.

[0020] As shown in FIG. 1, the shield electrode 112 is connected to an AC voltage output unit 122, and an AC voltage is applied when each sensor electrode 111 self-capacitively detects the capacitance between the fingertip FT. The AC voltage applied from the AC voltage output unit 122 to the shield electrode 112 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, titanium oxide, etc. as an example. When the sensor electrode 111 is 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. 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, instead of the AC voltage output units 121 and 122, one AC voltage output unit can be used, a variable amplifier can be provided between the AC voltage output unit and the sensor electrode 111, and a variable amplifier can be provided between the AC voltage output unit and the shield electrode 112, and the amplification factor can be adjusted 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. The first region 111A where each sensor electrode 111 is provided is located inside (inner side) the second region 112A where the shield electrode 112 is provided. Here, for clarity, 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. Since 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 the wiring 114B. The wiring 114B is an example of a voltage setting unit that sets the adjustment electrode 113 to the ground potential (ground voltage) as a fixed potential. Actually, as shown in FIG. 2B, six adjustment electrodes 113 are provided, and all the adjustment electrodes 113 are grounded via the wiring 114B. The adjustment electrode 113 is made of a conductive material such as an ITO film, zinc oxide, tin oxide, titanium oxide, etc. as an 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] In a plan view, as shown in FIG. 2B, the adjustment electrode 113 is provided inside the rectangular outer edge of the shield electrode 112 and is arranged so as to be within the outer edge of each sensor electrode 111. In a plan view, the adjustment electrode 113 is smaller than the sensor electrode 111. In a plan view, the six third regions 113A where the six adjustment electrodes 113 are provided are respectively located inside the six first regions 111A where the six sensor electrodes 111 are provided. Here, for easy understanding, the third region 113A is shown outside the outer edge of the adjustment electrode 113, but the outer edge of the third region 113A is equal to the outer edge of the adjustment electrode 113. Also, since all the sensor electrodes 111 are arranged inside the rectangular outer edge of the shield electrode 112 in a plan view, all the third regions 113A where all the adjustment electrodes 113 are arranged are located inside (inside) the second region where the shield electrode 112 is arranged. The details of the function of the adjustment electrode 113 will be described 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 with an amplitude Vrx to the sensor electrode 111 selected by a multiplexer (not shown) or the like in a time-division manner. The AC voltage output unit 122 applies an AC voltage with an amplitude Vas to the shield electrode 112. The amplitude Vas is larger than the amplitude Vrx. That is, 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. Also, the detection circuit 130 can detect the XY coordinates and Z coordinates of the fingertip FT when the fingertip FT is in a state of approaching the top panel 101, and can detect the XY coordinates of the fingertip FT when the fingertip FT is in a state of contacting the top panel 101. Note that the approach means that the operation surface of the top panel 101 and the fingertip FT are not in contact, but it is a state where it is possible to determine based on the capacitance between each sensor electrode 111 and the fingertip FT that the fingertip FT is approaching the operation surface.

[0027] <Capacitance detection method> Here, the capacitance detection method will be described with reference to FIGS. 4A, 4B, and 4C. The contents shown in FIGS. 4A, 4B, and 4C are not prior art, but are diagrams for explaining the principle of each detection method.

[0028] FIG. 4A is a diagram for explaining the self-capacitance type capacitance detection method (self-capacitance detection). FIG. 4A is a diagram showing a state in which the capacitance of the fingertip FT is detected in a self-capacitance manner using only the sensor electrode Rx without using a shield electrode. It is equivalent to that there is a capacitor Crf with a coupling capacitance Crf between the fingertip FT and the sensor electrode Rx, and there is a capacitor Crg with a coupling capacitance Crg between the sensor electrode Rx and the 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] An AC voltage with an amplitude Vrx is applied to the sensor electrode Rx. When the potential of the sensor electrode Rx is Vrx, positive charges are generated on the electrode of the capacitor Crg on the sensor electrode Rx side, and negative charges are generated on the electrode on the ground GND side. At this time, negative charges are generated on the electrode of the capacitor Crf on the fingertip FT side, and positive charges are generated on the electrode on the sensor electrode Rx side.

[0030] In the self-capacitance detection shown in FIG. 4A, a numerical value proportional to the charge generated on the sensor electrode Rx side, that is, a numerical value proportional to Crf + Crg, is detected. Further, for the capacitance of the capacitor Crg, the proportion occupied by the base capacitance such as the capacitance between metals in the wiring board and the capacitance between the electrodes of the touch panel is large, and since the base capacitance drifts due to environmental changes, it is not easy to accurately detect the capacitance Crf between the fingertip FT and the sensor electrode Rx.

[0031] FIG. 4B is a diagram for explaining an absolute self-capacitance type capacitance detection method (absolute self-capacitance detection). FIG. 4B is a diagram showing a state in which the capacitance of the fingertip FT is detected in an absolute self-capacitance manner using the sensor electrode Rx and the shield electrode AS. It is equivalent to having a capacitor Crf with a coupling capacitance Crf between the fingertip FT and the sensor electrode Rx, and a capacitor Crs with a coupling capacitance Crs 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, respectively, no charge is generated in the capacitor Crs, so the influence of the ground GND is eliminated, and the capacitance between the fingertip FT and the sensor electrode Rx can be accurately detected.

[0033] FIG. 4C is a diagram for explaining an absolute self-capacitance type capacitance detection method (absolute self-capacitance detection). The absolute self-capacitance detection shown in FIG. 4C is different 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, respectively, but the amplitude Vas of the AC voltage applied to the shield electrode AS is larger than the amplitude Vrx of the AC voltage applied to the sensor electrode Rx.

[0034] Since the amplitude Vas of the alternating voltage applied to the shield electrode AS is different from the amplitude Vrx of the alternating voltage applied to the sensor electrode Rx, positive and negative charges are generated on the two electrodes of the capacitor Crs. When positive and negative charges exist on the two electrodes of the capacitor Crs in this way, it has less influence than the self-capacitance detection shown in Fig. 4A, but it affects the position detection of the fingertip FT, and a slight drift due to environmental changes occurs.

[0035] On the premise that the amplitude Vas of the alternating voltage applied to the shield electrode 112 of the capacitance detection device 100 of the embodiment is different from the amplitude Vrx of the alternating voltage applied to the sensor electrode 111, the drift due to environmental changes is suppressed. Here, the explanation will be made using Fig. 5 in which the signs + and - of the charges are added to Fig. 1. Fig. 5 is a diagram for explaining the absolute self-capacitance detection of the embodiment.

[0036] As shown in Fig. 5, in the capacitance detection device 100 including the adjustment electrode (AJ) 113, let the amplitude of the alternating voltage applied to the sensor electrode (Rx) 111 be Vrx, the amplitude of the alternating voltage applied to the shield electrode (AS) 112 be Vas, the fixed potential of the adjustment electrode (AJ) 113 be Va, the coupling capacitance between the sensor electrode 111 and the shield electrode 112 be Crs, and the coupling capacitance between the sensor electrode 111 and the adjustment electrode 113 be Cra. The capacitor with the coupling capacitance Crs will be referred to as the capacitor Crs, and the capacitor with the coupling capacitance Cra will be referred to as the capacitor Cra for explanation. Although the fixed potential of the adjustment electrode 113 is described as Va, here Va = 0V.

[0037] Since the amplitude Vas of the alternating voltage applied to the shield electrode 112 is larger than the amplitude Vrx of the alternating voltage applied to the sensor electrode 111, positive charges are generated on the electrode (lower electrode) on the shield electrode 112 side of the capacitor Crs, and negative charges are generated on the electrode (upper electrode) on the sensor electrode 111 side of the capacitor Crs. Conversely, since the amplitude (0 V because it is GND) of the alternating voltage applied to the adjustment electrode 113 is smaller than the alternating voltage Vrx applied to the sensor electrode 111, positive charges are generated on the electrode (upper electrode) on the sensor electrode 111 side of the capacitor Cra, and negative charges are generated on the electrode (lower electrode) on the adjustment electrode 113 side of the capacitor Cra. Also, positive charges are generated on the electrode (lower electrode) on the sensor electrode Rx111 side of the capacitor Crf, and negative charges are generated on the electrode (upper electrode) on the fingertip FT side of the capacitor Crf.

[0038] If the charges of the capacitor Crs and the capacitor Cra are offset, it becomes possible to detect a value proportional only to the charge (capacitance) of the capacitor Crf. For this purpose, since it is sufficient to add the negative charge on the electrode (upper electrode) on the sensor electrode 111 side of the capacitor Crs and the positive charge on the electrode (upper electrode) on the sensor electrode 111 side of the capacitor Cra to become zero, the following equation (1) should hold.

[0039] [Number]

[0040] If equation (1) holds, the charges of the capacitor Crs and the capacitor Cra can be offset, so that no charge is generated between the sensor electrode 111 and the shield electrode 112 and the adjustment electrode 113. This is the same as the state where no charge is generated in the capacitor Crs in FIG. 4B.

[0041] Even if the condition of equation (1) for preventing charge generation between the sensor electrode 111 and the shield electrode 112 and the adjustment electrode 113 is not completely satisfied, or even if a value close to the value of Cra that satisfies equation (1) is used, the effect of offsetting the charges of the capacitor Crs and the capacitor Cra can be obtained.

[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 of Equation (1) means that it includes setting a value slightly shifted from the value obtained from Equation (1) in this way.

[0043] As an example, when Vrx = 0.95Vas, Crs:Cra = 0.95×Vas:0.05×Vas, and Crs:Cra = 19:1. By obtaining the coupling capacitance Cra that satisfies such a ratio from Equation (1) and designing the sensor electrode 111, the shield electrode 112, and the adjustment electrode 113. Since the capacitors Crs and Cra are present in one wiring board and the electrode-to-electrode distances are equal, the relationship of Crs:Cra = 19:1 can be easily realized by the ratio of the areas of the capacitors Crs and Cra.

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

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

[0046] On the premise that the amplitude Vas of the alternating voltage applied to the shield electrode 112 is larger than the amplitude Vrx of the alternating voltage applied to the sensor electrode 111, an adjustment electrode 113 that capacitively couples with the sensor electrode 111 is provided, and the adjustment electrode 113 is set to a fixed potential (here, the ground potential). Therefore, the influence of drift due to environmental changes such as temperature and humidity on the capacitance value between the sensor electrode 111 and the shield electrode 112 and the adjustment electrode 113 can be suppressed.

[0047] Therefore, a capacitance detection device 100 capable of suppressing the influence of drift due to environmental changes such as temperature and humidity on the capacitance value can be provided.

[0048] Also, assuming that the amplitude of the first alternating voltage is Vrx, the amplitude of the second alternating 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, it has the coupling capacitance Cra between the sensor electrode 111 and the adjustment electrode 113 determined based on the relational expression of Equation (1). In order to cancel out the charges of the capacitor Crs and the capacitor Cra, the coupling capacitance Cra between the sensor electrode 111 and the adjustment electrode 113 is adjusted so as to satisfy the conditions of Equation (1). Therefore, a capacitance detection device 100 capable of more reliably suppressing the influence of drift due to environmental changes such as temperature and humidity on the capacitance value can be provided.

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

[0050] Further, the sensor electrode 111 is provided on the 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 the second surface (the surface on the -Z direction side) opposite to the first surface (the surface on the +Z direction side) of the insulating layer 115A. The first surface (the surface on the +Z direction side) of the insulating layer 115A is located on the side where the fingertip FT approaches the sensor electrode 111. Even if there is a ground potential member or the like that is held at the ground potential in the -Z direction from the shield electrode 112, it is possible to effectively suppress the influence of the ground potential member or the like on the detection of the fingertip FT by the sensor electrode 111, and it is possible to more reliably and easily suppress the influence of drift due to environmental changes such as temperature and humidity of the capacitance value. Thus, a capacitance detection device 100 can be provided.

[0051] Further, the sensor electrode 111, the shield electrode 112, and the adjustment electrode 113 are provided on a wiring board having a laminated structure, and the shield electrode 112 and the adjustment electrode 113 are provided in the same layer different from the sensor electrode 111. Therefore, the inter-electrode distance between the shield electrode 112 and the sensor electrode 111 and the inter-electrode distance between the adjustment electrode 113 and the sensor electrode 111 can be made equal, and it becomes easier to set the conditions of formula (1). For this reason, a capacitance detection device 100 can be provided that can more reliably and easily suppress the influence of drift due to environmental changes such as temperature and humidity of the capacitance value. If only capacitors formed by the shield electrode 112 and the adjustment electrode 113 are added, it is possible to provide, for example, a chip capacitor or the like outside the wiring board. However, in such a case, since the characteristics such as the change in dielectric constant due to environmental changes such as temperature and humidity are different between the wiring board and the chip capacitor, adjustment according to formula (1) becomes difficult. On the other hand, if the sensor electrode 111, the shield electrode 112, and the adjustment electrode 113 are provided on the same wiring board, since the influence of drift due to environmental changes such as temperature and humidity of the capacitance value is uniform, a capacitance detection device 100 can be provided that can be more reliably and easily suppressed.

[0052] In addition, since the sensor electrode 111 and the shield electrode 112 are arranged to face each other, and the sensor electrode 111 and the adjustment electrode 113 are arranged to face each other, the condition of formula (1) can be surely set, and a capacitance detection device 100 capable of more surely and easily suppressing the influence of drift due to environmental changes such as temperature and humidity of the capacitance value can be provided.

[0053] In addition, in a plan view, the first region 111A where the sensor electrode 111 is provided is located inside the second region 112A where the shield electrode 112 is provided, and in a plan view, the third region 113A where the adjustment electrode 113 is provided is located inside the first region 111A and the second region 112A. Therefore, the condition of formula (1) can be surely set, and a capacitance detection device 100 capable of more surely and easily suppressing the influence of drift due to environmental changes such as temperature and humidity of the capacitance value can be provided.

[0054] In addition, since the shield electrode 112 is provided on the second side opposite to the first side of the sensor electrode 111 where the fingertip FT approaches the sensor electrode 111, even if there is a ground potential member or the like held at the ground potential in the -Z direction relative to the shield electrode 112, the influence of the ground potential member or the like on the detection of the fingertip FT by the sensor electrode 111 can be effectively suppressed, and a capacitance detection device 100 capable of more surely and easily suppressing the influence of drift due to environmental changes such as temperature and humidity of the capacitance value can be provided. Further, by providing the shield electrode 112 and the adjustment electrode 113 on the second side opposite to the first side of the sensor electrode 111 where the fingertip FT approaches the sensor electrode 111, the shield electrode 112 and the adjustment electrode 113 can be arranged at a position not visible to the user. In particular, by arranging the adjustment electrode 113 on the back side of the sensor electrode 111, an increase in the coupling capacitance between the fingertip FT and the adjustment electrode 113 as the fingertip FT approaches can be suppressed. Also by this, a capacitance detection device 100 capable of more surely and easily suppressing the influence of drift due to environmental changes such as temperature and humidity of the capacitance value can be provided.

[0055] Note that, in the above description, the form in which the potential of the adjustment electrode 113 is set to a fixed potential has been described. However, an AC voltage Va having an amplitude smaller than the amplitude of the AC voltage Vrx applied to the sensor electrode 111 and having the same frequency and phase as the AC voltage applied to the sensor electrode 111 may be applied to the adjustment electrode 113. The AC voltage Va applied to the adjustment electrode 113 in this way 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. If an AC voltage having an amplitude smaller than the amplitude of the AC voltage Vrx applied to the sensor electrode 111 is applied, a charge distribution similar to that in FIG. 5 can be generated in the sensor electrode 111, the shield electrode 112, and the adjustment electrode 113. Therefore, if the coupling capacitance Cra between the sensor electrode 111 and the adjustment electrode 113 is adjusted so as to satisfy the following equation (2) identical to equation (1), it is possible to provide the capacitance detection device 100 that can more reliably suppress the influence of drift due to environmental changes such as temperature and humidity of the capacitance value.

[0056]

Number

[0057] Also, assuming that 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 111 and the shield electrode 112 is Crs, and the coupling capacitance between the sensor electrode 111 and the adjustment electrode 113 is Cra, it has the coupling capacitance Cra between the sensor electrode 111 and the adjustment electrode 113 determined based on the relational expression of equation (2). In order to cancel out the charges of the capacitor Crs and the capacitor Cra, the coupling capacitance Cra between the sensor electrode 111 and the adjustment electrode 113 is adjusted so as to satisfy the condition of equation (2). Therefore, it is possible to provide the capacitance detection device 100 that can more reliably suppress the influence of drift due to environmental changes such as temperature and humidity of the capacitance value.

[0058] Further, an alternating voltage having the same frequency as the alternating voltage applied to the sensor electrode 111 and having a phase opposite to that of the alternating voltage applied to the sensor electrode 111 may be applied to the adjustment electrode 113. Such an alternating voltage with a reverse phase is also an example of the third alternating voltage. When applying an alternating voltage with a reverse phase to the adjustment electrode 113 as the third alternating voltage, the amplitude of the third alternating voltage does not necessarily have to be smaller than the amplitude Vrx of the alternating voltage, and the amplitude of the third alternating voltage may be any magnitude. The third alternating voltage may be output from an alternating voltage output unit (an example of a voltage setting unit) similar to the alternating voltage output units 121 and 122. In the case of a reverse phase, the coupling capacitance Cra between the sensor electrode 111 and the adjustment electrode 113 may be adjusted so as to satisfy the following equation (3) obtained by transforming equation (2).

[0059] [Number]

[0060] By applying an alternating voltage with a reverse phase to the adjustment electrode 113, when the charge distribution as shown in FIG. 5 is obtained, compared with the case where the adjustment electrode 113 is at the ground potential, the capacitor Cra can further cancel the charges, and it is possible to provide a capacitance detection device 100 that can more effectively and reliably suppress the influence of drift due to environmental changes such as temperature and humidity of the capacitance value.

[0061] Also, assuming that the amplitude of the first alternating voltage is Vrx, the amplitude of the second alternating voltage is Vas, the amplitude of the third alternating voltage having a phase opposite to that of the first alternating 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, the coupling capacitance Cra between the sensor electrode 111 and the adjustment electrode 113 is determined based on the relational expression of the following equation (3). In order to cancel the charges of the capacitor Crs and the capacitor Cra, the coupling capacitance Cra between the sensor electrode 111 and the adjustment electrode 113 is adjusted so as to satisfy the condition of equation (2), so that it is possible to provide a capacitance detection device 100 that can more reliably suppress the influence of drift due to environmental changes such as temperature and humidity of the capacitance value.

[0062] In the above description, the form in which only the sensor electrode 111 is provided on the upper surface of the insulating layer 115A has been described. However, similar to the shield electrode 112 shown in FIG. 2B, a shield electrode 112 surrounding the sensor electrode 111 on the upper surface of the insulating layer 115A may be provided. By providing the shield electrode 112 around the sensor electrode 111, the coupling capacitance with a metal member or the like of the surrounding ground potential can be reduced, and a capacitance detection device 100 capable of more reliably suppressing the influence of drift due to environmental changes such as temperature and humidity of the capacitance value can be provided.

[0063] <Modification Example of Adjustment Electrode 113> FIG. 6 is a diagram showing a modification example of the adjustment electrode 113. In FIG. 6, similar to FIG. 2B, a planar configuration of a portion including the shield electrode 112, the adjustment electrode 113, and the insulating layer 115B in the sensor unit 110 is shown.

[0064] As shown in FIG. 6, the adjustment electrode 113 may be a plurality of strip-shaped electrodes extending along the X-axis. In FIG. 6, the +X-direction ends of seven adjustment electrodes 113 arranged in the Y direction are connected by a 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 of Crs:Cra = 19:1 can be easily and accurately realized.

[0066] As described above, the capacitance detection device according to the exemplary embodiment of the present disclosure has been described. However, the present disclosure is not limited to the specifically disclosed embodiments, and various modifications and changes 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, and the entire contents thereof are incorporated herein by reference.

Description of Reference Numerals

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

Claims

1. A sensor electrode, a shield electrode disposed close 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 the self-capacitance value of the sensor electrode, an adjustment electrode disposed close to the sensor electrode, a voltage setting unit that outputs 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 the amplitude of the first AC voltage, or a third AC voltage having the same frequency as the first AC voltage and a phase opposite to that of the first AC voltage to the adjustment electrode, or sets the adjustment electrode to a fixed potential A capacitance detection device comprising the above components.

2. When 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, the capacitance detection device according to Claim 1, having the coupling capacitance Cra between the sensor electrode and the adjustment electrode determined based on the relational expression of the following formula (1). 【Number 1】

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

4. When 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 in phase with 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, having the coupling capacitance Cra between the sensor electrode and the adjustment electrode determined based on the relational expression of the following formula (2). 【Number 2】

5. When 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 out of phase with 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, having the coupling capacitance Cra between the sensor electrode and the adjustment electrode determined based on the relational expression of the following formula (3). 【Mathematics 3】

6. The sensor electrode is provided on the first surface of the insulating layer. The electrostatic capacitance detection device according to any one of claims 1 to 5, wherein the shield electrode and the adjustment electrode are provided on a second surface of the insulating layer, which is opposite to the first surface.

7. The electrostatic capacitance detection device according to any one of claims 1 to 5, 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. The electrostatic capacitance detection device according to any one of claims 1 to 5, wherein the sensor electrode and the shield electrode are arranged to face each other, and the sensor electrode and the adjustment electrode are arranged to face each other.

9. In a plan view, a first region where the sensor electrode is provided is located inside a second region where the shield electrode is provided. The electrostatic capacitance detection device according to any one of claims 1 to 5, wherein in a plan view, a third region where the adjustment electrode is provided is located inside the first region and the second region.

10. The electrostatic capacitance detection device according to any one of claims 1 to 5, wherein the shield electrode and the adjustment electrode are provided on a second side of the sensor electrode, which is opposite to a first side of the sensor electrode where an object approaches.

Images