CAPACITIVE DETECTION DEVICE

Abstract

A capacitive detection device is provided which is capable of suppressing the effect of capacitance drift due to changes in the environment, including temperature and humidity. The capacitive detection device comprises a sensor electrode, a shielding electrode located near the sensor electrode, a first voltage output unit which outputs a first AC voltage to the sensor electrode, a second voltage output unit which applies a second AC voltage to the shielding electrode, having the same frequency and phase as the first AC voltage and a larger amplitude than the amplitude of the first AC voltage, a detection unit which detects the intrinsic capacitance of the sensor electrode, an adjustment electrode located near the sensor electrode, and a voltage adjustment unit.which outputs to the adjusting electrode a third alternating voltage with the same frequency as the first alternating voltage, the same phase as the first alternating voltage and an amplitude that is smaller than the amplitude of the first alternating voltage, or a third alternating voltage with the same frequency as the first alternating voltage and a phase that is opposite to the phase of the first alternating voltage, or which sets the adjusting electrode to a fixed potential.

Description

Technical area

[0001] The present invention relates to a capacitive detection device. background

[0002] Proximity / touch sensors (capacitive detection devices) are known in which, in addition to an upper electrode (sensor electrode) and a lower electrode, a shielding electrode is provided around the lower electrode and a ground electrode is provided around the shielding electrode and which are capable of measuring the capacitance of the lower electrode without being influenced by surrounding elements (see, for example, Patent literature 1).Citation listPatent literature

[0003] PTL 1: Japanese Unexamined Patent Application Publication No. 2019-149207 Summary of the inventionTechnical problem

[0004] However, with respect to capacitive detection devices that apply different voltages to a sensor electrode and a shielding electrode, it has not been disclosed how to suppress an effect of drift in detected capacitance due to changes in an environment including temperature and humidity.

[0005] One aim is therefore to provide a capacitive detection device capable of suppressing an effect of temperature drift in the capacitance. Solution to the problem

[0006] A capacitive detection device according to an embodiment of the present disclosure comprises a sensor electrode, a shielding electrode arranged near 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 to the shielding electrode, which has a frequency and phase identical to the first alternating voltage and a larger amplitude than the amplitude of the first alternating voltage, a detection unit that detects a self-capacitance of the sensor electrode, an adjustment electrode arranged near the sensor electrode, and a voltage adjustment unit that applies a third alternating voltage to the adjustment electrode with a frequency identical to the first alternating voltage, a phase identical to the first alternating voltage, and an amplitude smaller than the amplitude of the first alternating voltage.or outputs a third alternating voltage having the same frequency as the first alternating voltage and a phase opposite to a phase of the first alternating voltage, or which sets the setting electrode to a fixed potential. Advantageous effects of the invention

[0007] A capacitive detection device capable of suppressing the effect of drift in capacitance due to changes in an environment, including temperature and humidity, can be provided. Brief Description of the Drawings [ Fig. 1] Fig. 1 is a diagram illustrating a capacitive detection device according to an embodiment. [ Fig. 2A] Fig. 2A is a diagram showing a planar configuration of a part of a sensor unit including a sensor electrode and an insulation layer. [ Fig. 2B] Fig. 2B is a diagram showing a planar configuration of a part of the sensor unit including a shield electrode, adjustment electrodes, and an insulation layer. [ Fig. 3] Fig. 3 is a diagram showing a configuration of the sensor unit 110 in cross section. [ Fig. 4A] Fig. Figure 4A is a diagram illustrating self-capacitance detection. [ Fig. 4B] Fig. Figure 4B is a diagram illustrating absolute self-capacitance detection. [ Fig. 4C] Fig. Figure 4C is another diagram illustrating absolute self-capacitance detection. [ Fig. 5] Fig. 5 is a diagram detecting an absolute self-capacitance according to the embodiment. [ Fig. 6] Fig. Figure 6 is a diagram illustrating a modification of the adjustment electrodes. Description of the embodiments

[0008] An embodiment in which a capacitive detection device is applied in the present disclosure will be described below. <Ausführungsform>

[0009] Fig. Figure 1 is a diagram showing a capacitive detection device 100 according to the embodiment. An XYZ coordinate system is defined and described below. Although a -Z direction is referred to as downward and a +Z direction as upward for convenience, these terms do not express a universal vertical relationship. Viewing in an XY plane is referred to as a plan view.

[0010] The capacitive 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.

[0011] The capacitive detection device 100 detects the approach or contact of a body part, such as a hand, to or with the top panel 101. An upper surface of the top panel 101 is an operation surface of an input device or the like that includes the capacitive detection device 100. The body part, such as a hand, is an example of a target that can be detected by the capacitive detection device 100. A case in which a user brings one of their fingertips FT close to the top panel 101 will be described below. Although a mode in which the top panel 101 is a component of the capacitive detection device 100 is described here, the top panel 101 may instead be a component of the input device that includes the capacitive detection device 100.

[0012] The sensor unit 110 includes sensor electrodes (Rx) 111, a shield electrode (AS) 112, adjustment electrodes (AJ) 113, and insulation layers 115A and 115B. The sensor unit 110 is realized, for example, by a printed circuit board having a multilayer structure in which the insulation layer 115B, the shield electrode 112 and the adjustment electrodes 113, the insulation layer 115A, and the sensor electrodes 111 are stacked in this order from bottom to top.

[0013] The shield electrode 112 and the adjustment electrodes 113 are provided on a second surface of the insulating layer 115A, which is opposite to a first surface in the +Z direction. The shield electrode 112 and the adjustment electrodes 113 are provided in the -Z direction (second side) of the sensor electrodes 111, which is opposite to the +Z direction (first side) in which the fingertip FT approaches the sensor electrodes 111. Since the insulating layer 115A is extremely thin, the shield electrode 112 and the adjustment electrodes 113 are provided close to the sensor electrodes 111.

[0014] The following description refers to the Fig. 2A, Fig. 2B and Fig. 3 in addition to Fig. 1. Fig. 2A is a diagram showing a planar configuration of a part of the sensor unit 110 including the sensor electrodes 111 and the insulation layer 115A. Fig. 2B is a diagram showing a planar configuration of a part of the sensor unit 110, which includes the shield electrode 112, the adjustment electrodes 113, and the insulation layer 115B. Fig. 2A shows six sensor electrodes 111, and Fig. Figure 2B shows a shielding electrode 112 and six adjustment electrodes 113. The sensor electrodes 111 comprise a first layer of the wiring board to reach the sensor unit 110. The shielding electrode 112 and the adjustment electrodes 113 are included in a second layer of the wiring board to realize the sensor unit 110. The shielding electrode 112 and the adjustment electrodes 113 are thus provided in the same layer, which is different from the one in which the sensor electrodes 111 are provided. Fig. 2A and the insulation layer 115A shown in Fig. 2B are of equal size in plan view (length in an X direction and length in a Y direction).

[0015] Fig. 3 is a diagram showing a cross-sectional configuration of the sensor unit 110. A cross section in Fig. 3 corresponds to a cross section along an arrow AA in Fig. 2A and a cross section along an arrow BB in Fig. 2B. A Fig. 1 part shown corresponds to a part of the cross section in Fig. 3 and comprises a shielding electrode 112 and a setting electrode 113.

[0016] In one example, the sensor unit 110 comprises six sensor electrodes 111 (see Fig. 2A), a shielding electrode 112 (see Fig. 2B) and six adjustment electrodes 113 (see Fig. 2B).

[0017] As in Fig. As shown in Figure 2A, the six sensor electrodes 111 are arranged, for example, in a matrix of two rows and three columns. A wire 114A is connected to each sensor electrode 111. The sensor electrode 111 is an electrode that detects capacitance with respect to the fingertip FT using a self-capacitance method and is made of a conductive material such as an ITO (indium tin oxide) layer, a zinc oxide, a tin oxide, or a titanium oxide. When the sensor electrodes 111 are formed using an ITO layer, the insulating layer 115A may be made of a transparent substrate.

[0018] The sensor electrodes 111 are connected to the AC voltage output unit 121 and the detection circuit 130 via the wires 114A (see Fig. 2A). Although in Fig. 1 one sensor electrode 111 is shown, there are actually six sensor electrodes 111, as in Fig. 2A. For this reason, a selection unit such as a multiplexer may be provided between the six sensor electrodes 111 and the one AC voltage output unit 121, and between the six sensor electrodes 111 and the one detection circuit 130, for example, and establish a connection in a time-division multiplexing manner. When detecting the self-capacitance with respect to the fingertip FT using the self-capacitance method, each sensor electrode 111 is connected to the detection circuit 130 and is also connected to the AC voltage output unit 121 and receives an AC voltage. The AC voltage applied from the AC voltage output unit 121 to each sensor electrode 111 is an example of a first AC voltage.

[0019] As in Fig. As shown in Figure 1, the shield electrode 112 is connected to the AC voltage output unit 122 and receives an AC voltage when each sensor electrode 111 detects the capacitance with respect to the fingertip FT using the 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 formed using a conductive material such as an ITO film, a zinc oxide, a tin oxide, or a titanium oxide. When the sensor electrodes 111 are an ITO film, the shield electrode 112 and the adjustment electrodes 113 may be formed using ITO films, and the insulating layers 115A and 115B may be made of transparent substrates.

[0020] In one example, the AC voltage applied by the AC voltage output unit 121 to each sensor electrode 111 and the AC voltage applied by 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 by the AC voltage output unit 122 to the shield electrode 112 is greater than the amplitude Vrx of the AC voltage applied by 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, an AC voltage output unit may be used instead of the AC voltage output unit 121 and the AC voltage output unit 122, and a variable gain amplifier may be provided between the AC voltage output unit and the sensor electrodes 111, and another variable gain amplifier may be provided between the AC voltage output unit and the shield electrode 112 to adjust a gain ratio so that the amplitude Vas becomes larger than the amplitude Vrx.

[0021] In plan view, a rectangular outer edge of the Fig. 2B shown shielding electrode 112 rectangular outer edges of the six in Fig. 2A. A first region 111A, in which each sensor electrode 111 is provided, is located within a second region 112A, in which the shield electrode 112 is provided. Although the first regions 111A are illustrated outside the outer edges of the corresponding sensor electrodes 111 for clarity, the outer edges of the first regions 111A correspond to the outer edges of the corresponding sensor electrodes 111. Likewise, although the second region 112A is depicted outside the outer edge of the shield electrode 112, the outer edge of the second region 112A coincides with the outer edge of the shield electrode 112. Since the six adjustment electrodes 113 are arranged within the rectangular outer edge of the shield electrode 112, the shield electrode 112 includes non-forming parts 112B structured to avoid the six adjustment electrodes 113.

[0022] As in Fig. 1, the adjustment electrodes 113 are grounded via wires 114B. The wires 114B are examples of a voltage adjustment unit that sets the adjustment electrode 113 to a ground potential as a fixed potential. Although the six adjustment electrodes 113 are arranged in practice as shown in Fig. 2B, all adjustment electrodes 113 are grounded via wires 114B. In one example, adjustment electrodes 113 are fabricated using a conductive material such as an ITO layer, a zinc oxide, a tin oxide, or a titanium oxide. When sensor electrodes 111 are made of an ITO layer, adjustment electrodes 113 and shield electrode 112 may be fabricated using ITO layers, and insulation layers 115A and 115B may be transparent substrates.

[0023] In plan view, the adjustment electrodes 113 are provided within the rectangular outer edge of the shielding electrode 112 and arranged to be supported within the outer edges of the corresponding sensor electrodes 111, as shown in Fig. 2B. In the plan view, the adjustment electrodes 113 are smaller than the sensor electrodes 111. In the plan view, six third regions 113A in which the six adjustment electrodes 113 are provided are located within the six first regions 111A in which the six sensor electrodes 111 are provided. Although the third regions 113A are shown outside the outer edges of the adjustment electrodes 113 for clarity, the outer edges of the third regions 113A coincide with the outer edges of the adjustment electrodes 113. Since all the sensor electrodes 111 are arranged within the rectangular outer edge of the shield electrode 112 in the plan view, all the third regions 113A in which all the adjustment electrodes 113 are arranged are located inside ("inside") the second region in which the shield electrode 112 is arranged. Details of the functions of the adjustment electrodes 113 will be described later.

[0024] The AC voltage output units 121 and 122 are AC voltage sources that output AC voltages to be applied to the sensor electrodes 111 and the shield electrode 112, respectively. The AC voltage output unit 121 applies an AC voltage of amplitude Vrx to a sensor electrode 111 in a time-divided manner, which is selected by a multiplexer or the like (not shown). The AC voltage output unit 122 applies an AC voltage of amplitude Vas to the shield electrode 112. The amplitude Vas is greater than the amplitude Vrx. That is, an AC voltage with a larger amplitude than that of the sensor electrodes 111 is applied to the shield electrode 112.

[0025] The detection circuit 130 detects the self-capacitances of the connected sensor electrodes 111. More specifically, the detection circuit 130 detects the capacitance between each sensor electrode 111 and the fingertip FT in a time-divided manner. The detection circuit 130 can detect XY coordinates and a Z coordinate of the fingertip FT when the fingertip FT is close to the upper panel 101 and the XY coordinates of the fingertip FT when the fingertip FT is in contact with the upper panel 101. Proximity refers to a state in which the operation surface of the upper panel 101 and the fingertip FT are not in contact with each other, but based on the capacitance between each sensor electrode 111 and the fingertip FT, it can be determined that the fingertip FT is close to the operation surface. < Method for detecting capacity >

[0026] Methods for detecting capacity are described here with reference to the Fig. 4A, Fig. 4B and Fig. 4C. What is described in the Fig. 4A, Fig. 4B and Fig. 4C does not concern the related prior art, but the principles of the methods for detection.

[0027] Fig. 4A is a diagram illustrating a method for detecting self-capacitance (self-capacitance detection). Fig. 4A is a diagram illustrating a state in which the capacitance of the fingertip FT is detected by a self-capacitance method using only the sensor electrode Rx without using a shield electrode. It can be essentially assumed that a capacitor Crf with a coupling capacitance Crf is provided between the fingertip FT and the sensor electrode Rx, and a capacitor Crg with a coupling capacitance Crg is provided between the sensor electrode Rx and the ground GND. When a position of the fingertip FT changes relative to the sensor electrode Rx, the coupling capacitance Crf changes. A main purpose of a self-capacitance detection sensor is to detect the capacitance Crf as a value and measure a positional relationship between the sensor electrode Rx and the fingertip FT.

[0028] When an alternating voltage with an amplitude of Vrx is applied to the sensor electrode Rx and the potential of the sensor electrode Rx is equal to Vrx, a positive charge is generated in one electrode of the capacitor Crg on one side of the sensor electrode Rx, and a negative charge is generated in one electrode on one side of the ground GND. At this time, a negative charge is generated in one electrode of the capacitor Crf on one side of the fingertip FT, and a positive charge is generated in one electrode on the side of the sensor electrode Rx.

[0029] At the Fig. In the self-capacitance detection shown in Figure 4A, a value proportional to the charge generated at the sensor electrode Rx, that is, a value proportional to Crf + Crg, is detected. Since the capacitance of the capacitor Crg is mainly based on a base capacitance, which includes capacitance between the metals in a circuit board and capacitance between electrodes in the touch panel, it is not easy to accurately detect the capacitance Crf between the fingertip FT and the sensor electrode Rx because a drift in the base capacitance is caused due to changes in an environment.

[0030] Fig. Figure 4B is a diagram illustrating an absolute self-capacitance method for detecting capacitance (absolute self-capacitance detection). Fig. 4B is a diagram illustrating a state in which the capacitance of the fingertip FT is detected by an absolute self-capacitance method using the sensor electrode Rx and the shield electrode AS. It can be essentially assumed that a capacitor Crf with a coupling capacitance Crf is present between the fingertip FT and the sensor electrode Rx, and a capacitor Crs with a coupling capacitance Crs is present between the sensor electrode Rx and the shield electrode AS. The frequency, amplitude Vrx, and phase of an alternating voltage applied to the sensor electrode Rx are the same as the frequency, amplitude Vas, and phase of an alternating voltage applied to the shield electrode AS.

[0031] Since no charge is generated in the capacitor Crs when the frequency, amplitude Vrx and phase of the AC voltage applied to the sensor electrode Rx and the frequency, amplitude Vas and phase of the AC voltage applied to the shield electrode AS are the same, an effect of the ground GND is eliminated, and the capacitance between the fingertip FT and the sensor electrode Rx can be accurately detected.

[0032] Fig. Figure 4C is a diagram illustrating another absolute self-capacitance method for detecting capacitance (absolute self-capacitance detection). Fig. The absolute self-capacitance detection shown in Figure 4C differs from that shown in Fig. 4B in that the frequency and a phase of an alternating voltage applied to the sensor electrode Rx and the frequency and a phase of an alternating voltage applied to the shielding electrode AS are the same, but the amplitude Vas of the alternating voltage applied to the shielding electrode AS is greater than the amplitude Vrx of the alternating voltage applied to the sensor electrode Rx.

[0033] Since the amplitude Vas of the alternating voltage applied to the shielding electrode AS differs from the amplitude Vrx of the alternating voltage applied to the sensor electrode Rx, positive and negative charges are generated in the two electrodes of the capacitor Crs, respectively. When positive and negative charges are present in the two electrodes of the capacitor Crs, the detection of the fingertip position FT is impaired, although the effect is less than in the Fig. 4A, and there is a slight drift due to changes in an environment.

[0034] The capacitive detection device 100 according to the embodiment suppresses drift due to changes in an environment, assuming that the amplitude Vas of the alternating voltage applied to the shield electrode 112 and the amplitude Vrx of the alternating voltage applied to the sensor electrodes 111 are different from each other. This will be described here with reference to Fig. 5, which is created by adding plus and minus signs to Fig. 1 is obtained. Fig. 5 is a diagram illustrating detection of absolute self-capacitance according to the embodiment.

[0035] As in Fig. 5, in the capacitive detection device 100 including the adjustment electrodes (AJ) 113, the amplitude of the alternating voltage applied to the sensor electrodes (Rx) 111 is denoted by Vrx, the amplitude of the alternating voltage applied to the shielding electrode (AS) 112 is denoted by Vas, the fixed potential of the adjustment electrodes (AJ) 113 is denoted by Va, the coupling capacitance between the sensor electrodes 111 and the shielding electrode 112 is denoted by Crs, and the coupling capacitance between the sensor electrodes 111 and the adjustment electrodes 113 is denoted by Cra. The capacitor with the coupling capacitance Crs is referred to as a capacitor Crs in the following description, and a capacitor with the coupling capacitance Cra is referred to as a capacitor Cra. The fixed potential of the adjustment electrodes 113, denoted by Va, is 0 V here.

[0036] Since the amplitude Vas of the AC voltage applied to the shield electrode 112 is greater than the amplitude Vrx of the AC voltage applied to the sensor electrodes 111, a positive charge is generated in one electrode (lower electrode) of the capacitor Crs on one side of the shield electrode 112, and a negative charge is generated in one electrode (upper electrode) of the capacitor Crs on one side of the sensor electrodes 111. Conversely, since the amplitude (0 V due to GND) of the AC voltage applied to the adjustment electrodes 113 is smaller than the AC voltage Vrx applied to the sensor electrodes 111, a positive charge is generated in one electrode (upper electrode) of the capacitor Cra on the side of the sensor electrodes 111, and a negative charge is generated in one electrode (lower electrode) of the capacitor Cra on one side of the adjustment electrodes 113.Positive charge is generated in one electrode (lower electrode) of the capacitor Crf on the side of the sensor electrodes Rx 111, and negative charge is generated in one electrode (upper electrode) of the capacitor Crf on one side of the fingertip FT.

[0037] When the charges of capacitors Crs and Cra cancel each other out, a value proportional only to the charge (capacitance) of capacitor Crf can be detected. For this purpose, the sum of the negative charge in the electrode (upper electrode) of capacitor Crs on the sensor electrode 111 side and the positive charge in the electrode (upper electrode) of capacitor Cra on the sensor electrode 111 side must be zero, that is, the following expression (1) must be satisfied. [Math. 1] Crs×(Vas−Vrx)=Cra×(Vrx−Va)

[0038] When expression (1) is satisfied, the charges of the capacitors Crs and Cra cancel each other out, and no charge is generated between the sensor electrodes 111 and both the shield electrode 112 and the adjustment electrodes 113. This is the same state as when the capacitor Crs in Fig. 4B no charge is generated.

[0039] Even if the condition of expression (1) of not generating charge between the sensor electrodes 111 and both the shield electrode 112 and the adjustment electrodes 113 is not perfectly satisfied, an effect of canceling the charges of the capacitors Crs and Cra can be produced by using a value close to a value of Cra that satisfies expression (1).

[0040] Therefore, regarding the coupling capacitance Cra, if it is said that the coupling capacitance Cra determined based on the relationship expression of Expression (1) is achieved between the sensor electrodes 111 and the adjustment electrodes 113, a value slightly different from the value obtained from Expression (1) can be set.

[0041] For example, if Vrx = 0.95Vas, Crs:Cra = 0.95 × Vas:0.05 × Vas, and Crs:Cra = 19:1. The sensing electrodes 111, the shielding electrode 112, and the adjusting electrodes 113 can be designed so that the coupling capacitance Cra satisfies this relationship in Expression (1). Since the capacitors Crs and Cra are located in a printed circuit board and the distances between the electrodes are equal, the ratio Crs:Cra = 19:1 can be easily achieved based on the area ratio of the capacitors Crs and Cra.

[0042] Setting a value slightly different from the value obtained from the expression (1) described above means, for example, keeping Cra less than 1 in the ratio of Crs:Cra = 19:1 obtained from the expression (1), which is achieved, for example, by changing the area ratio. <effekte>

[0043] As described above, the capacitive detection device 100 includes the sensor electrodes 111, the shield electrode 112 arranged near the sensor electrodes 111, the AC voltage output unit 121 that outputs the first AC voltage Vrx to the sensor electrodes 111, the AC voltage output unit 122 that applies the second AC voltage Vrx to the shield electrode 112, which has the same frequency and phase as the first AC voltage Vrx and an amplitude greater than the first AC voltage Vrx, the detection circuit 130 that detects the self-capacitances of the sensor electrodes 111, the adjustment electrodes 113 arranged near the sensor electrodes 111, and the voltage adjustment units that adjust the adjustment electrodes 113 to the fixed potential Va.

[0044] Since the adjustment electrodes 113 capacitively coupled to the sensor electrodes 111 are provided and the adjustment electrodes 113 are set to a fixed potential (here, ground potential), assuming 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 electrodes 111, an effect of a drift in the capacitance between the sensor electrodes 111 and both the shield electrode 112 and the adjustment electrodes 113 due to changes in an environment including temperature and humidity can be suppressed.

[0045] A capacitive detection device 100 capable of suppressing an effect of capacitance drift due to changes in an environment, including temperature and humidity, may be provided.

[0046] In addition, when the amplitude of the first AC voltage is denoted by Vrx, the amplitude of the second AC voltage is denoted by Vas, the fixed potential is denoted by Va, the coupling capacitance between the sensor electrodes 111 and the shield electrode 112 is denoted by Crs, and the coupling capacitance between the sensor electrodes 111 and the adjustment electrodes 113 is denoted by Cra, the coupling capacitance Cra between the sensor electrodes 111 and the adjustment electrodes 113 determined based on the relational expression of Expression (1) is achieved.Since the coupling capacitance Cra between the sensor electrodes 111 and the adjustment electrodes 113 is adjusted to satisfy the condition of Expression (1) so that the charges of the capacitors Crs and Cra cancel each other, a capacitive detection device 100 capable of more reliably suppressing an effect of capacitance drift due to changes in an environment including temperature and humidity can be provided.

[0047] Since the fixed potential Va is the ground potential (Va = 0 V), the adjustment electrodes 113 can be easily adjusted to the fixed potential Va, and a capacitive detection device 100 capable of suppressing an effect of capacitance drift due to changes in an environment including temperature and humidity with a simple configuration can be provided.

[0048] The sensor electrodes 111 are provided on the first surface (the surface in the +Z direction) of the insulating layer 115A, and the shield electrode 112 and the adjustment electrodes 113 are provided on the second surface (the surface in the -Z direction) of the insulating layer 115A opposite to the first surface (the surface in the +Z direction). The first surface (the surface in the +Z direction) of the insulating layer 115A is located on a side on which the fingertip FT approaches the sensor electrodes 111. Even if a ground potential element or the like maintained at the ground potential is present in the -Z direction of the shield electrode 112, a capacitive detection device 100 capable of detecting an effect of the ground potential element or the like can be provided.to effectively suppress the detection of the fingertip FT by means of the sensor electrodes 111 and to more reliably and easily suppress an effect of capacitance drift due to changes in an environment including temperature and humidity.

[0049] Since the sensor electrodes 111, the shield electrode 112, and the adjustment electrodes 113 are provided on the circuit board with the multilayer structure, and the shield electrode 112 and the adjustment electrodes 113 are provided in the same layer different from that of the sensor electrodes 111, the inter-electrode distances between the shield electrode 112 and the sensor electrodes 111 and the inter-electrode distances between the adjustment electrodes 113 and the sensor electrodes 111 can be made equal to each other, and the condition of Expression (1) can be easily set. Therefore, a capacitive detection device 100 capable of more reliably and easily suppressing the effect of capacitance drift due to changes in an environment, including temperature and humidity, can be provided.If only capacitors based on the shield electrode 112 and the adjustment electrodes 113 are added, for example, chip capacitors or the like can be provided outside the circuit board. However, in this case, it becomes difficult to make adjustments using Expression (1) because the characteristics of permittivity changes and the like due to changes in an environment including temperature and humidity are different between the circuit board and the chip capacitors. On the other hand, by providing the sensor electrodes 111, the shield electrode 112, and the adjustment electrodes 113 on the same circuit board, the effect of capacitance drift due to changes in an environment including temperature and humidity becomes consistent, and a capacitive detection device 100 capable of suppressing the effect more reliably and easily can be provided.

[0050] Since the sensor electrodes 111 and the shield electrode 112 are arranged in a manner to face each other, and the sensor electrodes 111 and the setting electrodes 113 are arranged in a manner to face each other, a capacitive detection device 100 can be provided which is capable of reliably setting the state of expression (1) and suppressing an effect of capacitance drift due to changes in an environment including temperature and humidity more reliably and easily.

[0051] Since, in plan view, the first regions 111A in which the sensor electrodes 111 are provided are located within the second region 112A in which the shield electrode 112 is provided, and the third regions 113A in which the adjustment electrodes 113 are provided are located within the first regions 111A and the second region 112A, a capacitive detection device 100 capable of reliably adjusting the condition of expression (1) and suppressing an effect of capacitance drift due to changes in an environment including temperature and humidity more reliably and easily can be provided.

[0052] Since the shield electrode 112 is provided on the second side of the sensor electrodes 111, which is opposite to the first side in which the fingertip FT approaches the sensor electrodes 111, even if a ground potential element or the like held at ground potential is present in the -Z direction of the shield electrode 112, a capacitive detection device 100 can be provided that is capable of effectively suppressing an effect of the ground potential element or the like on the detection of the fingertip FT by the sensor electrodes 111 and more reliably and easily suppressing an effect of capacitance drift due to changes in an environment including temperature and humidity.Furthermore, since the shield electrode 112 and the adjustment electrodes 113 are provided on the second side of the sensor electrodes 111, which is opposite to the first side where the fingertip FT approaches the sensor electrodes 111, the shield electrode 112 and the adjustment electrodes 113 can be arranged in positions invisible to the user. In particular, by disposing the adjustment electrodes 113 behind the sensor electrodes 111, it is possible to suppress an increase in the coupling capacitance between the fingertip FT and the adjustment electrodes 113 caused by the approach of the fingertip FT. In this case, too, a capacitive detection device 100 capable of more reliably and easily suppressing the effect of capacitance drift due to changes in an environment including temperature and humidity can be provided.

[0053] Although a mode has been described in which the potential of the adjustment electrodes 113 is a fixed potential, an alternating voltage Va may instead be applied to the adjustment electrodes 113 whose amplitude is smaller than the amplitude Vrx of the alternating voltage applied to the sensor electrodes 111 and whose frequency and phase are the same as those of the alternating voltage applied to the sensor electrodes 111. The alternating voltage Va applied to the adjustment electrodes 113 in this way is an example of a third alternating voltage. The third alternating voltage may be output from an alternating voltage output unit (an example of a voltage adjustment unit) similar to the alternating voltage output units 121 and 122. When an alternating voltage is applied whose amplitude is smaller than the amplitude Vrx of the alternating voltage applied to the sensor electrodes 111, a charge distribution similar to Fig. 5 in the sensor electrodes 111, the shield electrode 112, and the adjustment electrodes 113. Therefore, by adjusting the coupling capacitance Cra between the sensor electrodes 111 and the adjustment electrodes 113 in such a manner as to satisfy Expression (2), which is identical to Expression (1), a capacitive detection device 100 capable of more reliably and easily suppressing an effect of capacitance drift due to changes in an environment including temperature and humidity can be provided. [Math. 2] Crs×(Vas−Vrx)=Cra×(Vrx−Va)

[0054] When the amplitude of the first AC voltage is denoted by Vrx, the amplitude of the second AC voltage is denoted by Vas, the amplitude of the third AC current whose phase is the same as that of the first AC voltage is denoted by Va, the coupling capacitance Crs between the sensor electrodes 111 and the shield electrode 112 is denoted by Crs, and the coupling capacitance between the sensor electrodes 111 and the adjustment electrodes 113 is denoted by Cra, the coupling capacitance Cra between the sensor electrodes 111 and the adjustment electrodes 113 determined based on a relational expression of Expression (2) is achieved.Since the coupling capacitance Cra between the sensor electrodes 111 and the adjustment electrodes 113 is adjusted to satisfy the condition of Expression (2) so that the charges of the capacitors Crs and Cra cancel each other, a capacitive detection device 100 capable of more reliably suppressing an effect of capacitance drift due to changes in an environment including temperature and humidity can be provided.

[0055] Alternatively, an alternating voltage may be applied to the adjustment electrodes 113 whose frequency is the same as that of the alternating voltage applied to the sensor electrodes 111 and whose phase is opposite to that of the alternating voltage applied to the sensor electrodes 111. This alternating voltage, which has an opposite phase, is also an example of the third alternating voltage. When the alternating voltage, which has the opposite phase, is applied to the adjustment electrodes 113 as the third alternating voltage, the amplitude of the third alternating voltage does not have to be smaller than the amplitude Vrx of the alternating voltage, but can have any amplitude. The third alternating voltage may be output from an alternating voltage output unit (an example of a voltage adjustment unit) similar to the alternating voltage output units 121 and 122.In the case of the opposite phase, the coupling capacitance Cra between the sensor electrodes 111 and the adjustment electrodes 113 can be adjusted so as to satisfy the following expression (3), which is obtained by transforming the expression (2). [Math. 3] Crs×(Vas−Vrx)=Cra×(Vrx+Va)

[0056] By applying the alternating voltage, which has the opposite phase, to the adjusting electrodes 113, the capacitor Cra can hold more charge than if the Fig. 5 is established and the adjustment electrodes 113 are at the ground potential, and a capacitive detection device 100 capable of more effectively and reliably suppressing an effect of capacitance drift due to changes in an environment including temperature and humidity can be provided.

[0057] When the amplitude of the first AC voltage is denoted by Vrx, the amplitude of the second AC voltage is denoted by Vas, the amplitude of the third AC voltage whose phase is opposite to that of the first AC voltage is denoted by Va, the coupling capacitance between the sensor electrodes 111 and the shield electrode 112 is denoted by Crs, and the coupling capacitance between the sensor electrodes 111 and the adjustment electrodes 113 is denoted by Cra, the coupling capacitance Cra between the sensor electrodes 111 and the adjustment electrodes 113 determined based on the relational expression of the following expression (3) is achieved.Since the coupling capacitance Cra between the sensor electrodes 111 and the adjustment electrodes 113 is adjusted to satisfy the condition of expression (2) so that the charges of the capacitors Crs and Cra cancel each other, a capacitive detection device 100 capable of more reliably suppressing an effect of capacitance drift due to changes in an environment including temperature and humidity can be provided.

[0058] Although a mode in which only the sensor electrodes 111 are provided on the upper surface of the insulating layer 115A has been described above, the shield electrode 112 surrounding the sensor electrodes 111 on the upper surface of the insulating layer 115A may be provided as shown in Fig. 2B can be provided. By providing the shield electrode 112 around the sensor electrodes 111, the coupling capacitance with respect to nearby metal elements and the like having the ground potential can be reduced, and a capacitive detection device 100 capable of more reliably suppressing an effect of drift in capacitance due to changes in an environment including temperature and humidity can be provided. < Modification of adjustment electrodes 113>

[0059] Fig. 6 is a diagram illustrating a modification of the adjustment electrodes 113. As in Fig. 2B shows Fig. 6 shows a planar configuration of a part of the sensor unit 110, which includes the shielding electrode 112, the adjustment electrodes 113 and the insulation layer 115B.

[0060] As in Fig. 6, the adjustment electrodes 113 may be a plurality of strip electrodes extending along an X-axis. In Fig. 6, the ends extending in a +X direction of the seven adjustment electrodes 113 arranged in a Y direction are connected to each other by means of a wire 114B extending in the Y direction.

[0061] With the adjustment electrodes 113, the ratio Crs:Cra = 19:1 can be easily and accurately achieved by setting a ratio of a width W1 of the shielding electrode 112 between the adjustment electrodes 113 to a width W2 of the adjustment electrodes 113 in the Y direction to 19:1.

[0062] Although a capacitive detection device according to an exemplary embodiment of the present disclosure has been described above, the present disclosure is not limited to the specifically disclosed embodiment and may be modified or changed in various ways without departing from the claims.

[0063] This international application claims priority from Japanese Patent Application No. 2022-080013, filed on May 16, 2022, the entire contents of which are incorporated herein by reference. List of reference symbols 100 capacitive detection device 101 upper panel 110 Sensor unit 111 Sensor electrode 111A first area 112 Shielding electrode 112A second area 113 Adjustment electrode 113A third area 115A, 115B insulation layer 121, 122 AC voltage output unit 130 Detection circuit QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 2019-149207

[0003] JP 2022-080013

[0063] < / effekte>

Claims

[1] A capacitive detection device comprising: a sensor electrode; a shielding electrode arranged near 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 to the shielding electrode a second alternating voltage having the same frequency and phase as the first alternating voltage and having an amplitude greater than an amplitude of the first alternating voltage; a detection unit which detects a self-capacitance of the sensor electrode; a setting electrode arranged near the sensor electrode; and a voltage setting unit which outputs to the setting electrode a third alternating voltage which has a same frequency as the first alternating voltage, a same phase as the first alternating voltage and an amplitude which is smaller than the amplitude of the first alternating voltage, or a third alternating voltage which has a same frequency as the first alternating voltage and a phase which is opposite to a phase of the first alternating voltage, or which sets the setting electrode to a fixed potential. [2] The capacitive detection device according to claim 1, where, when the amplitude of the first AC voltage is denoted by Vrx, the amplitude of the second AC voltage is denoted by Vas, the fixed potential is denoted by Va, the coupling capacitance between the sensor electrode and the shield electrode is denoted by Crs, and the coupling capacitance between the sensor electrode and the adjustment electrode is denoted by Cra, the coupling capacitance Cra, determined on a basis of a relationship expression of the following expression (1), is achieved between the sensor electrode and the adjustment electrode. [Math. 1] Crs×(Vas−Vrx)=Cra×(Vrx−Va) [3] The capacitive detection device according to claim 2, wherein the fixed potential is a ground potential. [4] The capacitive detection device according to claim 1, where, when the amplitude of the first AC voltage is denoted by Vrx, the amplitude of the second AC voltage is denoted by Vas, the amplitude of the third AC voltage which has the same phase as the first AC voltage is denoted by Va, coupling capacitance between the sensor electrode and the shield electrode is denoted by Crs, and coupling capacitance between the sensor electrode and the adjustment electrode is denoted by Cra, the coupling capacitance Cra determined on a basis of a relationship expression of the following expression (2) is achieved between the sensor electrode and the adjustment electrode. [Math. 2] Crs×(Vas−Vrx)=Cra×(Vrx−Va) [5] The capacitive detection device according to claim 1, where, when the amplitude of the first AC voltage is denoted by Vrx, the amplitude of the second AC voltage is denoted by Vas, the amplitude of the third AC voltage having the opposite phase to the phase of the first AC voltage is denoted by Va, the coupling capacitance between the sensor electrode and the shield electrode is denoted by Crs, and the coupling capacitance between the sensor electrode and the adjustment electrode is denoted by Cra, wherein the coupling capacitance Cra, which is determined on the basis of a relationship expression of the following expression (3), is achieved between the sensor electrode and the adjustment electrode. [Math. 3] Crs×(Vas−Vrx)=Cra×(Vrx+Va) [6] The capacitive detection device according to any one of claims 1 to 5, wherein the sensor electrode is provided on a first surface of an insulating layer, and wherein the shielding electrode and the adjusting electrode are provided on a second surface of the insulating layer opposite to the first surface. [7] The capacitive 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 circuit board having a multi-layer structure, and the shield electrode and the adjustment electrode are provided in a same layer which is different from a layer in which the sensor electrode is provided. [8] The capacitive detection device according to any one of claims 1 to 7, wherein the sensor electrode and the shield electrode are arranged in a manner to face each other, and the sensor electrode and the adjustment electrode are arranged in a manner to face each other. [9] The capacitive detection device according to any one of claims 1 to 8, wherein, in plan view, a first region in which the sensor electrode is provided is located within a second region in which the shielding electrode is provided, and wherein, in plan view, a third region in which the adjustment electrode is provided is located within the first region and the second region. [10] The capacitive detection device according to any one of claims 1 to 9, wherein the shielding electrode and the adjusting electrode are provided on a second side of the sensor electrode which is opposite to a first side on which a target object approaches the sensor electrode.

Images