JP2014126456A - Capacitance type detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a capacitance type detection device capable of easily achieving a structure for precisely detecting a displacement of a moving member irrespective of a gap between the moving member and a detection electrode and an ambient temperature.SOLUTION: The capacitance type detection device includes: a detection electrode 2 disposed facing a moving member 1 which moves along an x-direction together with a target; and a reference electrode 3 disposed facing the moving member 1 near the detection electrode 2. The detection electrode 2 is formed in a shape that the capacitance with respect to the moving member 1 changes accompanying a displacement along the x-direction of the moving member 1. The reference electrode 3 is formed in a shape that the capacitance does not change with respect to the moving member 1 irrespective of a displacement along the x-direction of the moving member 1.

Description

  The present invention relates to a capacitance type detection device.

  2. Description of the Related Art Conventionally, a capacitance type detection device that obtains displacement of an object is known, and is disclosed in, for example, Patent Document 1. The signal processing circuit of the differential capacitance type transducer described in Patent Document 1 includes two divided electrodes arranged on the same plane, a common electrode that can move in the x direction while facing the divided electrodes via a gap. It is used for the differential capacitance type transducer comprised by these. Capacitances Ca and Cb that increase and decrease due to the movement of the common electrode in the x direction are formed between the divided electrodes and the common electrode, respectively.

  This signal processing circuit includes a CV conversion circuit that converts a high-frequency current flowing through two capacitances into a voltage, a subtraction circuit that subtracts an AC voltage output of each CV conversion circuit, and each CV conversion circuit. And an adder circuit for adding the AC voltage outputs. In addition, this signal processing circuit synchronously detects the AC voltage output of the subtracting circuit and the adding circuit to obtain a DC output voltage proportional to (Ca−Cb) and (Ca + Cb), and the adding circuit output is always constant. And a feedback circuit that controls the direct current potential so as to become the direct current potential.

  In this signal processing circuit, an error is compensated when the common electrode moves with an inclination rather than in a parallel state, that is, when each capacitance change has a first order error.

Japanese Patent Laying-Open No. 2005-077280

  In the above conventional example, when the gap or ambient temperature between the common electrode (moving body) and each divided electrode (detection electrode) changes, the displacement amount of the common electrode can be obtained without depending on the gap or ambient temperature. However, in the above conventional example, the sum of the area facing the common electrode (moving body) of one divided electrode and the area facing the common electrode of the other divided electrode is constant regardless of the movement of the common electrode. Thus, it is necessary to form each divided electrode.

  For this reason, when the common electrode moves linearly, it is easy to configure as described above. However, for example, when the common electrode rotates, it is necessary to form each divided electrode precisely. There was a problem that it was difficult.

  The present invention has been made in view of the above points, and is a capacitance that can easily realize a configuration that accurately obtains the displacement of the moving body regardless of the gap between the moving body and the detection electrode and the ambient temperature. An object of the present invention is to provide a type detection device.

  The capacitance type detection device of the present invention is arranged to face a moving body that moves in one direction together with an object, and to face the moving body in the vicinity of the detection electrode. A reference electrode, and the detection electrode is formed in a shape in which an electrostatic capacitance between the movable body and the movable body changes in accordance with the displacement along the one direction of the movable body. The movable body is formed in a shape in which the capacitance between the movable body and the movable body does not change depending on the displacement along the one direction.

  In this capacitance type detection device, it is preferable that the reference electrodes are respectively arranged on both sides of the detection electrode along a direction orthogonal to the one direction on a plane where the reference electrodes are arranged.

  In this capacitance type detection device, the reference electrode is preferably composed of a plurality of electrodes that are electrically independent from each other.

  In this capacitance type detection device, it is preferable that a plurality of the reference electrodes are provided, and that each of the reference electrodes has a different capacitance from the moving body.

  In this capacitance type detection device, it is preferable that the detection electrode and the reference electrode are formed on the inner substrate of a multilayer substrate formed by laminating a plurality of substrates made of a rigid substrate.

  In this capacitance type detection device, the rigid substrate is preferably made of a ceramic substrate.

  In this capacitance type detection device, it is preferable that at least a part of the multilayer substrate is integrally formed in a resin case.

  In this capacitance type detection device, it is preferable that a shield electrode connected to the same potential as the detection electrode is disposed at a position opposite to the moving body with the detection electrode interposed therebetween.

  In this capacitance type detection device, CV conversion for outputting a voltage based on a capacitance between the moving body and the detection electrode and a voltage based on a capacitance between the moving body and the reference electrode. It is preferable to include a processing unit including a circuit and an arithmetic circuit that obtains a displacement in the one direction of the moving body based on an output voltage of the CV conversion circuit.

  In this capacitance type detection device, the processing unit includes a signal processing circuit that converts an output voltage of the CV conversion circuit into a predetermined voltage and outputs the predetermined voltage. In the signal processing circuit, the moving body and the reference It is preferable to correct the capacitance between the moving body and the detection electrode based on the capacitance between the electrode and the electrode.

  In the capacitance type detection device, the processing unit may be configured such that in the CV conversion circuit, the electrostatic capacitance between the moving body and the detection electrode is based on an electrostatic capacity between the moving body and the reference electrode. It is preferable to correct the capacity.

  In this capacitance type detection device, it is preferable to have a terminal made of a metal plate electrically connected to the processing unit, and to connect the terminal by welding to the output electrode of the processing unit.

  The present invention compensates for changes in capacitance due to the gap between the moving body and the detection electrode and the ambient temperature by using a reference electrode whose capacitance does not change due to displacement in one direction of the moving body. The displacement of the moving object is obtained. Therefore, in the present invention, it is not necessary to form each electrode so that the sum of the area of the detection electrode facing the moving body and the area of the reference electrode facing the moving body is constant. That is, the present invention can easily realize a configuration that accurately obtains the displacement of the moving body regardless of the gap between the moving body and the detection electrode.

It is a perspective view which shows Embodiment 1 of the electrostatic capacitance type detection apparatus which concerns on this invention. It is operation | movement explanatory drawing of an electrostatic capacitance type detection apparatus same as the above, (a) is a circuit schematic diagram of a process part, (b) is a time chart figure which shows operation | movement of each CV conversion circuit. It is a circuit schematic diagram which shows the process part using the other compensation means in an electrostatic capacitance type detection apparatus same as the above. It is a figure which shows the other structure of each electrode in an electrostatic capacitance type detection apparatus same as the above, (a) is a perspective view, (b) is the top view seen from the z direction. It is a figure which shows Embodiment 2 of the electrostatic capacitance type detection apparatus which concerns on this invention, (a) is a perspective view, (b) is the top view seen from the z direction. It is a top view which shows each board | substrate which comprises the multilayer substrate in an electrostatic capacitance type detection apparatus same as the above. It is a figure which shows Embodiment 3 of the electrostatic capacitance type detection apparatus which concerns on this invention, (a) is a perspective view, (b) is the top view seen from the x direction when a moving body inclines. It is a flowchart figure which shows operation | movement of an electrostatic capacitance type detection apparatus same as the above. It is a figure which shows Embodiment 4 of the electrostatic capacitance type detection apparatus which concerns on this invention, (a) is a perspective view, (b) is the circuit schematic of a process part. (A), (b) is a figure which shows the other structure in an electrostatic capacitance type detection apparatus same as the above.

(Embodiment 1)
Hereinafter, a capacitive detection device according to a first embodiment of the present invention will be described with reference to the drawings. In the following description, the x direction, the y direction, and the z direction are defined by arrows shown in FIG. As shown in FIGS. 1 and 2A, the present embodiment includes a moving body 1, a detection electrode 2, a reference electrode 3, and a processing unit 4.

  The moving body 1 is formed in a long cylindrical shape along the y direction, and is attached to an object (not shown) whose displacement is to be calculated. In addition, the moving body 1 may be attached to the object via an intermediate member (not shown), or may be directly attached to the object. Furthermore, the moving body 1 may be a part of an object. The moving body 1 moves along the x direction (one direction) together with the object. Therefore, the displacement of the object can be obtained by obtaining the displacement of the moving body 1.

  The detection electrode 2 is a metal pattern formed on one surface in the z direction of the substrate P <b> 1 (surface on the front side in FIG. 1), and is disposed to face the moving body 1. The detection electrode 2 has a triangular shape in plan view, and is formed such that the width dimension in the y direction becomes larger toward the positive direction in the x direction. The shape of the detection electrode 2 is not limited to a triangular shape, and may be any shape as long as the width dimension in the y direction continuously changes along the x direction. That is, the detection electrode 2 only needs to have a shape in which the capacitance between the detection body 2 and the moving body 1 changes with the displacement of the moving body 1 in the x direction.

  The reference electrode 3 is a metal pattern formed on one surface in the z direction of the substrate P <b> 1 like the detection electrode 2, and is arranged to face the moving body 1 in the vicinity of the detection electrode 2. The reference electrode 3 has a rectangular shape elongated in the x direction in plan view, and is formed so that the width dimension in the y direction is constant. That is, the capacitance between the reference electrode 3 and the moving body 1 does not change due to the displacement of the moving body 1 in the x direction.

  Further, although not shown, a shield electrode made of a metal pattern is formed on the other surface in the z direction of the substrate P1 (the surface on the back side in FIG. 1). The shield electrode is not limited to the structure formed on the substrate on which the detection electrode 2 and the reference electrode 3 are formed, and is disposed at a position opposite to the moving body 1 across the electrodes 2 and 3. Any configuration may be used.

  The substrate P1 is a rigid substrate made of an insulating material. Since the rigid substrate has higher rigidity than the flexible substrate, the stability of the shapes of the electrodes 2 and 3 formed on the rigid substrate can be improved. Further, since the rigid substrate can be easily multi-layered as in the second embodiment to be described later, it is also suitable for arranging shield electrodes.

  In the present embodiment, a ceramic substrate is used as the substrate P1. Since the ceramic substrate is a substrate excellent in heat resistance and rigidity, its shape is stable even when used or manufactured under high temperatures. Further, since the ceramic substrate is a substrate excellent in chemical resistance and oil resistance, it can withstand use in a state exposed to the outside air.

  The processing unit 4 is provided, for example, on a substrate (not shown) different from the substrate P1, and as shown in FIG. 2A, the first CV conversion circuit 40, the second CV conversion circuit 41, and the first amplification A circuit 42, a second amplifier circuit 43, and an arithmetic circuit 44 are provided. Although not shown, the processing unit 4 also includes a drive circuit that drives switches SW1 to SW5 described later.

  The first CV conversion circuit 40 outputs a voltage based on the capacitance C0 between the moving body 1 and the detection electrode 2, and includes an operational amplifier OP1, a capacitor C1, and switches SW1 and SW2. The detection electrode 2 is connected to the switch SW1. By switching the switch SW1, the connection between the inverting input terminal of the operational amplifier OP1, the open position of the high impedance, the ground potential and the detection electrode 2 is periodically switched. The non-inverting input terminal of the operational amplifier OP1 is connected to the reference potential V1. The first CV conversion circuit 40 constitutes a negative feedback circuit by connecting a capacitor C1 between the inverting input terminal and the output terminal of the operational amplifier OP1. A switch SW2 is connected in parallel with the capacitor C1, and the capacitor C1 and the switch SW2 constitute a switched capacitor.

  The second CV conversion circuit 41 outputs a voltage based on the capacitance C0 'between the moving body 1 and the reference electrode 3, and includes an operational amplifier OP2, a capacitor C2, and switches SW3 and SW4. The reference electrode 3 is connected to the switch SW3. By switching the switch SW3, the connection between the inverting input terminal of the operational amplifier OP2, the open position of the high impedance, the ground potential and the detection electrode 3 is periodically switched. The non-inverting input terminal of the operational amplifier OP2 is connected to the reference potential V1. The second CV conversion circuit 41 forms a negative feedback circuit by connecting a capacitor C2 between the inverting input terminal and the output terminal of the operational amplifier OP2. A switch SW4 is connected in parallel with the capacitor C2, and the capacitor C2 and the switch SW4 constitute a switched capacitor.

  Hereinafter, the operation of each of the CV conversion circuits 40 and 41 will be described with reference to FIGS. First, it is assumed that the electrodes 2 and 3 are connected to the inverting input terminals of the operational amplifiers OP1 and OP2 through the switches SW1 and SW3, respectively, and the switches SW2 and SW4 are off. In this case, the operational amplifier OP1 outputs a voltage corresponding to the impedance ratio between the capacitance C0 and the capacitor C1. The operational amplifier OP2 outputs a voltage corresponding to the impedance ratio between the capacitance C0 'and the capacitor C2.

  Next, when the switches SW2 and SW4 are turned on, the output voltages of the operational amplifiers OP1 and OP2 are temporarily reset by discharging the charges accumulated in the capacitors C1 and C2. At this time, the capacitances C0 and C0 'are also reset by connecting the electrodes 2 and 3 to the ground potential via the switches SW1 and SW3. Thereafter, the switches SW1 and SW3 are switched to connect the electrodes 2 and 3 to the inverting input terminals of the operational amplifiers OP1 and OP2, respectively, and the switches SW2 and SW4 are switched on. Then, each operational amplifier OP1, OP2 outputs a voltage corresponding to the impedance ratio between the capacitances C0, C0 'and the capacitors C1, C2, respectively. By repeating the above operation, voltages VA1 and VB1 based on the capacitances C0 and C0 'are periodically output from the operational amplifiers OP1 and OP2, respectively.

  The shield electrode is connected to the reference potential V1 through the switch SW5. By switching the switch SW5, either the reference potential V1 or the ground potential and the shield electrode are periodically connected. Here, in the present embodiment, the switch SW5 is switched so that the potential of the shield electrode is always equal to that of the electrodes 2 and 3. As a result, charge is not charged or discharged between the electrodes 2 and 3 and the shield electrode.

  Therefore, even if another object exists at a position opposite to the electrodes 2 and 3 across the shield electrode, the capacitances C0 and C0 'do not change due to the presence of the object. In addition, by providing the shield electrode, it is possible to prevent fluctuations in the capacitances C0 and C0 'due to noise.

  The first amplifier circuit 42 amplifies and outputs the output voltage VA1 of the first CV conversion circuit 40, and corresponds to a signal processing circuit that converts the output voltage VA1 of the first CV conversion circuit 40 into a predetermined voltage and outputs it. . The first amplifier circuit 42 includes an operational amplifier OP3, resistors R1 and R2, and a switching element Q1 that is an N-channel MOSFET. The output voltage VA1 of the first CV conversion circuit 40 is input to the inverting input terminal of the operational amplifier OP3 via the resistor R1. The non-inverting input terminal of the operational amplifier OP3 is connected to the ground potential. The first amplifier circuit 42 forms a negative feedback circuit by connecting a series circuit of a resistor R2 and a switching element Q1 between the inverting input terminal and the output terminal of the operational amplifier OP3. A voltage V0 'described later is input to the gate terminal of the switching element Q1.

  The second amplifier circuit 43 amplifies and outputs the output voltage VB1 of the second CV conversion circuit 41, and corresponds to a signal processing circuit that converts the output voltage VB1 of the second CV conversion circuit 41 into a predetermined voltage and outputs it. . In addition to the same configuration as the first amplifier circuit 42, the second amplifier circuit 43 includes an operational amplifier OP4, a switching element Q2 that is an N-channel MOSFET, and resistors R3 and R4. The non-inverting input terminal of the operational amplifier OP4 is connected to the reference potential V2. The output voltage of the operational amplifier OP3 is input to the inverting input terminal of the operational amplifier OP4. The gate terminal of the switching element Q2 is connected to the output terminal of the operational amplifier OP4.

  The drain terminal of the switching element Q2 is connected to the reference potential V20 via the resistor R3. The source terminal of the switching element Q2 is connected to the ground potential via the resistor R4. A connection point between the resistor R3 and the switching element Q2 is connected to the gate terminal of the switching element Q1. Therefore, the voltage V0 'divided by the on-resistances of the resistors R3 and R4 and the switching element Q2 is input to the gate terminal of the switching element Q1.

  Hereinafter, the operation of each of the amplifier circuits 42 and 43 will be described. The operational amplifier OP3 of each of the amplifier circuits 42 and 43 amplifies and outputs the output voltages VA1 and VB1 of the respective CV conversion circuits 40 and 41, and the amplification factor depends on the on-resistances of the resistors R1 and R2 and the switching element Q1. decide. The on-resistance of the switching element Q1 is determined by the voltage V0 'input to the gate terminal.

  In the second amplifier circuit 43, the operational amplifier OP4 outputs a voltage based on the difference between the output voltage of the operational amplifier OP3 and the reference potential V2. The on-resistance of the switching element Q2 is determined by the output voltage of the operational amplifier OP4. The voltage V0 'is determined by the voltage division ratio based on the on-resistances of the resistors R3 and R4 and the switching element Q2, and the voltage V0' is input to the gate terminals of the switching elements Q1 of the amplifier circuits 42 and 43. That is, the amplification factors of the amplification circuits 42 and 43 are the same, and this amplification factor is controlled in the second amplification circuit 43 so that the output voltage of the operational amplifier OP3 matches the reference potential V2.

  Here, the output voltage VB1 of the second CV conversion circuit 41 changes based on the capacitance C0 ′, but the capacitance C0 ′ does not vary depending on the displacement of the moving body 1 in the main displacement direction (x direction). . On the other hand, the capacitance C0 'varies depending on the gap between the moving body 1, the detection electrode 2 and the reference electrode 3, and the fluctuation of the ambient temperature. The amount of change in the capacitance C0 'depending on the gap and the ambient temperature is considered to be the same for the capacitance C0. Therefore, by amplifying the output voltage VA1 of the first CV conversion circuit 40 using the amplification factor determined in the second amplifier circuit 43, the first amplifier circuit 42 outputs a voltage V0 that compensates for changes in the gap and ambient temperature. .

  The arithmetic circuit 44 is composed of, for example, a microcontroller, and obtains the displacement of the moving body 1 based on the output voltage V0. For example, when the moving body 1 moves in the positive direction of the x direction, the area of the detection electrode 2 facing the moving body 1 increases, and the capacitance C0 increases. Further, when the moving body 1 moves in the negative direction of the x direction, the area of the detection electrode 2 facing the moving body 1 is reduced, and the capacitance C0 is reduced. That is, since the capacitance C0 changes with the displacement of the moving body 1, the displacement of the moving body 1 can be obtained from the output voltage V0.

  As described above, in this embodiment, the reference electrode 3 is used in which the capacitance C0 'does not change due to the displacement of the moving body 1 in the x direction (one direction). Thereby, in this embodiment, the displacement of the mobile body 1 is calculated | required by compensating the change of the electrostatic capacitance C0 by the gap between the mobile body 1 and the detection electrode 2, or ambient temperature. For this reason, in this embodiment, it is necessary to form each electrode 2 and 3 so that the sum of the area facing the moving body 1 of the detection electrode 2 and the area facing the moving body 1 of the reference electrode 3 may be constant. There is no. That is, this embodiment can easily realize a configuration that accurately obtains the displacement of the moving body 1 regardless of the gap between the moving body 1 and the detection electrode 2.

  In this embodiment, the displacement of the moving body 1 can be accurately performed without being affected by the gap or the ambient temperature at any position in the range where the displacement of the moving body 1 is calculated (hereinafter referred to as “effective range”). Can be sought.

  Here, the means for compensating for the change in the capacitance C0 due to the gap between the moving body 1 and the detection electrode 2 and the ambient temperature (hereinafter referred to as “compensation means”) is a means using the already described amplification factor. It is not necessary to be limited to. Hereinafter, the processing unit 4 ′ using other compensation means will be described. As illustrated in FIG. 3, the processing unit 4 ′ includes peak hold circuits 45 and 46, an operational amplifier OP 5, a sine wave oscillation circuit 47, a current mirror circuit CM 1, a resistor R 5, and an arithmetic circuit 44.

  The peak hold circuit 45 holds a peak voltage of the voltage based on the capacitance C0, and corresponds to a CV conversion circuit. This peak voltage is given to the arithmetic circuit 44. Note that the voltage based on the capacitance C0 is determined by dividing the integral value of the current I1 supplied to the capacitance C0 by the capacitance C0. The peak hold circuit 46 holds the peak voltage of the voltage based on the capacitance C0 'and corresponds to a CV conversion circuit. This peak voltage is applied to the inverting input terminal of the operational amplifier OP5. Note that the voltage based on the capacitance C0 ′ is determined by dividing the integral value of the current I2 supplied to the capacitance C0 ′ by the capacitance C0 ′.

  The non-inverting input terminal of the operational amplifier OP5 is connected to the reference potential V3. A voltage based on the difference between the peak voltage of the peak hold circuit 46 and the reference potential V3 is output from the output terminal of the operational amplifier OP5 and applied to the sine wave oscillation circuit 47. The sine wave oscillation circuit 47 oscillates a sinusoidal AC voltage. The amplitude of the AC voltage increases or decreases depending on the output voltage of the operational amplifier OP5.

  The current mirror circuit CM1 includes switching elements Q2 and Q3 that are NPN transistors and switching elements Q4 to Q6 that are PNP transistors. The emitter of the switching element Q2 is connected to the sine wave oscillation circuit 47, and the base is connected to its own collector and the base of the switching element Q3. The collector of switching element Q2 is connected to each emitter of switching elements Q4 to Q6 via resistor R6. The emitter of switching element Q3 is connected to the ground potential via resistor R5, and the collector is connected to the collector and base of switching element Q4. The switching elements Q4 to Q6 connect their emitters and connect their bases to each other.

  The collector of the switching element Q5 is connected to the detection electrode 2 and supplies a current I1, which is a collector current, to the capacitance C0. The collector of the switching element Q6 is connected to the reference electrode 3, and supplies a current I2 that is a collector current to the capacitance C0 '. Here, the currents I1 and I2 are determined by the current flowing through the resistor R5, and the current flowing through the resistor R5 is determined by the amplitude of the AC voltage oscillated by the sine wave oscillation circuit 47. Therefore, the processing unit 4 ′ performs negative feedback control of the currents I <b> 1 and I <b> 2 so that the peak voltage of the voltage based on the capacitance C <b> 0 ′ matches the reference potential V <b> 3.

  As described above, the capacitance C0 ′ does not vary depending on the displacement in the main displacement direction (x direction) of the moving body 1, but the gap between the moving body 1, the detection electrode 2 and the reference electrode 3, Varies with temperature fluctuations. Therefore, the peak hold circuit 45 outputs a peak voltage that compensates for changes in the gap and the ambient temperature by supplying the same current I1 as the current I2 that fluctuates due to the increase / decrease in the capacitance C0 'to the capacitance C0. The arithmetic circuit 44 obtains the displacement of the moving body 1 based on this peak voltage.

  As described above, the compensation unit of the processing unit 4 ′ performs negative feedback control on the current I2 supplied to the capacitance C0 ′ so that the voltage based on the capacitance C0 ′ becomes a constant value, and the current I2 The same current I1 is supplied to the capacitance C0. The compensation means can compensate for changes in the gap between the moving body 1 and the detection electrode 2 and the ambient temperature.

  In the present embodiment, the detection electrode 2 and the reference electrode 3 have a configuration in which the moving body 1 moves linearly. However, when the moving body 1 rotates, for example, FIGS. The detection electrode 2 ′ and the reference electrode 3 ′ may be configured in the shape shown in b). In this configuration, it is assumed that the moving body 1 rotates clockwise or counterclockwise on a plane parallel to the xy plane with the shaft portion 10 as an axis. Note that the configuration of the processing unit 4 (processing unit 4 ') is the same as that already described.

  Each of the electrodes 2 'and 3' is formed on one surface in the z direction of the semicircular substrate P1 '. The detection electrode 2 ′ is formed in a shape in which the width dimension continuously changes along the rotation direction of the moving body 1. That is, the detection electrode 2 ′ is formed in a shape in which the capacitance between the detection body 2 ′ and the moving body 1 changes as the moving body 1 is displaced in the rotational direction. The reference electrode 3 ′ is formed in a shape whose width dimension is constant along the rotation direction of the moving body 1. That is, the capacitance between the reference electrode 3 ′ and the moving body 1 does not change depending on the displacement of the moving body 1 in the rotational direction.

  By configuring the electrodes 2 ′ and 3 ′ as described above and using the processing unit 4 (processing unit 4 ′), the mobile unit 1 can be configured with a simple structure regardless of the gap between the mobile unit 1 and the detection electrode 2 ′. The displacement in the rotation direction can be obtained with high accuracy.

  In the present embodiment, the detection electrodes 2 and 2 ′ are formed so that the width dimension changes continuously along the main displacement direction (x direction and rotation direction) of the moving body 1 in the effective range. . The detection electrodes 2 and 2 ′ do not necessarily have a continuous shape without being interrupted within the effective range, and may be divided into a plurality of electrodes. Even in this configuration, in the effective range, the capacitance between the moving body 1 and the detection electrodes 2 and 2 ′ changes substantially continuously with the displacement of the moving body 1. Can be requested.

(Embodiment 2)
Hereinafter, a capacitive detection device according to a second embodiment of the present invention will be described with reference to the drawings. In the following description, the x direction, the y direction, and the z direction are defined by arrows shown in FIG. Moreover, in the following description, the same number is attached | subjected to the site | part which is common in Embodiment 1, and description is abbreviate | omitted. In this embodiment, as shown in FIGS. 5 and 6, a multilayer substrate P2 is used instead of the substrate P1.

  The multilayer substrate P2 is formed by laminating a plurality (four in this embodiment) of substrates P20 to P23. Each of the substrates P20 to P23 is made of a rigid substrate. In the present embodiment, each of the substrates P20 to P23 is a ceramic substrate. Each of the substrates P20 to P23 is formed by integrally forming a rectangular main portion A1 elongated along the x direction and a rectangular protrusion A2 protruding from the main portion A1 along the y direction. The substrates P20 to P23 are stacked along the z direction in the order of P20, P21, P22, and P23 from the side closer to the moving body 1.

  An electronic component B1 constituting the processing unit 4 (processing unit 4 ') is mounted on one surface of the protrusion A2 of the substrate P20 (the front surface in FIG. 6). The detection electrode 2 and the reference electrode 3 are formed on one surface of the main part A1 of the substrate P21 (the surface on the front side in FIG. 6). The electrodes 2 and 3 have the same shape as the electrodes 2 and 3 of the first embodiment.

  On one surface of the main portion A1 of the substrate P22 (the surface on the front side in FIG. 6), a rectangular shield electrode S1 is formed in plan view. The shield electrode S1 has the same function as the shield electrode of the first embodiment. In addition, four through holes T1 are respectively provided through the boundary portion between the main portion A1 and the protrusion A2 of each of the substrates P20 to P23 at a certain interval along the x direction. The electrodes 2, 3 and the shield electrode S1 are electrically connected to the processing unit 4 (processing unit 4 ') through these through holes T1.

  As shown in FIG. 5A, the multilayer substrate P2 is integrally formed in a long resin case 5 along the x direction. The case 5 covers the boundary portion between the main portion A1 and the protrusion A2 in the multilayer substrate P2. Therefore, since the through hole T1 is covered with the case 5, it is not exposed to the outside. For this reason, the insulation with respect to the exterior of each electrode 2 and 3 is securable. Further, both end portions of the case 5 in the longitudinal direction are provided with attachment holes 50 penetrating along the z direction. By inserting a mounting screw (not shown) into the mounting hole 50 and screwing it, the present embodiment can be mounted at an arbitrary location.

  As described above, in the present embodiment, the detection electrode 2 and the reference electrode 3 are formed on the inner substrate P21 of the multilayer substrate P2. Therefore, in this embodiment, since each electrode 2 and 3 is not exposed outside, the insulation with respect to the exterior of each electrode 2 and 3 is securable. The electrodes 2 and 3 are preferably formed on the substrate closest to the moving body 1 among the substrates inside the multilayer substrate P2 as in this embodiment. In this configuration, the capacitances C0 and C0 'between the moving body 1 and the electrodes 2 and 3 can be easily detected, and even when an amplifier circuit is required, the amplification factor can be suppressed as small as possible.

(Embodiment 3)
Hereinafter, a capacitive detection device according to a third embodiment of the present invention will be described with reference to the drawings. In the following description, the x direction, the y direction, and the z direction are defined by arrows shown in FIG. Moreover, in the following description, the same number is attached | subjected to the site | part which is common in Embodiment 1, and description is abbreviate | omitted. In the present embodiment, as shown in FIG. 7, a pair of detection electrodes 2A and 2B and a pair of reference electrodes 3C and 3D are arranged on one surface in the z direction of the substrate P1 (the front side in FIG. 7A). On the surface).

  The detection electrodes 2A and 2B are each formed in a triangular shape in plan view. The detection electrode 2A is formed so that the width dimension in the y direction becomes larger toward the minus direction in the x direction. Further, the detection electrode 2B is formed so that the width dimension in the y direction increases as it goes in the positive direction in the x direction. Note that the shape of each of the detection electrodes 2A and 2B is not limited to a triangular shape, as long as the width dimension in the y direction continuously changes along the x direction. In other words, each of the detection electrodes 2A and 2B may have a shape in which the capacitance between the detection body 2A and 2B and the moving body 1 changes as the moving body 1 is displaced in the x direction.

  The reference electrodes 3C and 3D are each formed in a rectangular shape in plan view, and are arranged on the substrate P1 so as to sandwich the detection electrodes 2A and 2B. That is, the reference electrodes 3C and 3D are respectively arranged on both sides of the detection electrodes 2A and 2B along the y direction orthogonal to the x direction on the plane on which the reference electrodes 3C and 3D are arranged. Each reference electrode 3C, 3D has a width dimension in the y direction that does not change along the x direction. That is, the reference electrodes 3 </ b> C and 3 </ b> D do not change the capacitance with the moving body 1 due to the displacement of the moving body 1 in the x direction, and do not change the area facing the moving body 1.

  The processing unit 4 according to the present embodiment includes four CV conversion circuits (not shown) having the same configuration as the first CV conversion circuit 40 according to the first embodiment, and an arithmetic circuit (not shown). Each CV conversion circuit outputs a voltage proportional to the capacitance between the moving body 1 and each of the detection electrodes 2A and 2B and the capacitance between the moving body 1 and each reference electrode. Convert to digital value by / D conversion. In the following, digital values based on the capacitance between the moving body 1 and each of the detection electrodes 2A and 2B will be referred to as “capacitance CA and CB”, respectively, and between the moving body 1 and the reference electrodes 3C and 3D. The digital values based on the electrostatic capacitance are “capacitance CC and CD”, respectively.

  Here, the capacitances CA and CB basically vary continuously with the displacement of the moving body 1 in the x direction, but the gaps G1 and G2 between the moving body 1 and the respective detection electrodes 2A and 2B and the surroundings. It also fluctuates due to changes in temperature. On the other hand, the capacitances CC and CD do not vary depending on the displacement of the moving body 1 in the x direction, but, like the capacitances CA and CB, the gap G3 between the moving body 1 and the reference electrodes 3C and 3D. , Varies depending on changes in G4 and ambient temperature. Moreover, when each moving body 1 tilts in the y direction, each of the capacitances CA to CD varies with the tilt.

  Therefore, in the present embodiment, by correcting each capacitance CA, CB based on each capacitance CC, CD, a change in the gap between the moving body 1 and each detection electrode 2A, 2B, ambient temperature, and The displacement in the x direction that does not depend on the inclination of the moving body 1 in the y direction is obtained. Hereinafter, a method for correcting each of the capacitances CA and CB will be described with reference to FIG. In addition, each electrode 2A, 2B, 3C, 3D shall be arrange | positioned at equal intervals along the y direction, as shown in FIG.7 (b). In addition, the gap between each electrode 2A, 2B, 3C, 3D and the moving body 1 when the moving body 1 is not inclined in the y direction is referred to as a “reference gap G0”.

  First, the gaps G3 and G4 are calculated from the following equations using the capacitances CC and CD, the dielectric constant ε, and the areas SC and SD of the reference electrodes 3C and 3D facing the moving body 1.

G3 = ε · SC / CC
G4 = ε · SD / CD
Next, the gaps G1 and G2 are calculated from the following equations using the gaps G3 and G4.

G1 = (2.G3 + G4) / 3
G2 = (G3 + 2 · G4) / 3
Then, using the capacitances CA and CB, the gaps G1 and G2, and the reference gap G0, the corrected capacitances CA ′ and CB ′ are calculated from the following equations.

CA ′ = (G1 / G0) · CA
CB '= (G2 / G0) · CB
Finally, the displacement of the moving body 1 in the x direction is obtained based on the difference between the corrected capacitances CA ′ and CB ′. For example, when the moving body 1 moves in the positive direction of the x direction, the area of the detection electrode 2A facing the moving body 1 decreases, and the area of the detection electrode 2B facing the moving body 1 increases. Accordingly, in this case, the capacitance CB ′ is larger than the capacitance CA ′. Further, when the moving body 1 moves in the negative direction of the x direction, the area of the detection electrode 2A facing the moving body 1 increases, and the area of the detection electrode 2B facing the moving body 1 decreases. Therefore, in this case, the capacitance CA ′ is larger than the capacitance CB ′. That is, since the difference between the capacitances CA ′ and CB ′ changes with the displacement of the moving body 1 in the x direction, the displacement of the moving body 1 in the x direction is determined from the difference between the capacitances CA ′ and CB ′. Can be sought.

  As described above, in the present embodiment, in addition to changes in the gap between the moving body 1 and each of the detection electrodes 2A and 2B and the ambient temperature, the inclination of the moving body 1 in the y direction is compensated to compensate for the x of the moving body 1. Directional displacement can be determined.

  In the present embodiment, two detection electrodes 2A and 2B are used, but only one of them may be used. For example, if one detection electrode 2A and two reference electrodes 3C and 3D are used, the capacitance CA may be corrected based on the capacitances CC and CD. Even with this configuration, the same effects as described above can be obtained.

  In the present embodiment, the reference electrodes 3C and 3D are electrically independent from each other, but the reference electrodes 3C and 3D may be electrically connected. In this configuration, even if the moving body 1 is tilted along the y direction, the combined capacitance between the reference electrodes 3C and 3D and the moving body 1 hardly changes. Therefore, if each capacitance CA, CB is corrected based on this combined capacitance, in addition to the gap between the moving body 1 and each detection electrode 2A, 2B and changes in ambient temperature, the y direction of the moving body 1 The displacement in the x direction of the moving body 1 can be obtained by compensating for the inclination of the moving body 1.

  In addition, each electrode 2A, 2B, 3C, 3D of this embodiment may be formed on the multilayer substrate P2 of Embodiment 2 instead of the substrate P1. Even with this configuration, the same effects as in the present embodiment can be achieved.

(Embodiment 4)
Hereinafter, a fourth embodiment of the capacitance detection device according to the present invention will be described with reference to the drawings. In the following description, the x direction, the y direction, and the z direction are defined by arrows shown in FIG. Moreover, in the following description, the same number is attached | subjected to the site | part which is common in Embodiment 1, and description is abbreviate | omitted. In the present embodiment, as shown in FIG. 9, a pair of detection electrodes 2A and 2B and a pair of reference electrodes 3C and 3D are arranged on one surface in the z direction of the substrate P1 (the front side in FIG. 9A). On the surface).

  The detection electrodes 2A and 2B are each formed in a triangular shape in plan view. The detection electrode 2A is formed so that the width dimension in the y direction becomes larger toward the minus direction in the x direction. Further, the detection electrode 2B is formed so that the width dimension in the y direction increases as it goes in the positive direction in the x direction. Note that the shape of each of the detection electrodes 2A and 2B is not limited to a triangular shape, as long as the width dimension in the y direction continuously changes along the x direction. In other words, each of the detection electrodes 2A and 2B may have a shape in which the capacitance between the detection body 2A and 2B and the moving body 1 changes as the moving body 1 is displaced in the x direction.

  The reference electrodes 3C and 3D are each formed in a rectangular shape in plan view. Each reference electrode 3C, 3D has a width dimension in the y direction that does not change along the x direction. That is, the reference electrodes 3 </ b> C and 3 </ b> D do not change the capacitance with the moving body 1 due to the displacement of the moving body 1 in the x direction, and do not change the area facing the moving body 1. The reference electrodes 3C and 3D have different width dimensions in the y direction.

  As shown in FIG. 9B, the processing unit 4 of the present embodiment includes two first CV conversion circuits 40, two second CV conversion circuits 41, a first differential amplifier circuit 48, and a second differential. An amplifying circuit 49 and an arithmetic circuit 44 are provided. Each first CV conversion circuit 40 outputs a voltage proportional to the capacitances CA and CB between the moving body 1 and the detection electrodes 2A and 2B, respectively. Each second CV conversion circuit 41 outputs a voltage proportional to the capacitances CC and CD between the moving body 1 and the reference electrodes 3C and 3D, respectively.

  The first differential amplifier circuit 48 outputs a difference between output voltages of the first CV conversion circuits 40, and includes an operational amplifier OP6 and resistors R7 to R10. The output voltage of the first differential amplifier circuit 48 is proportional to the difference between the capacitances CA and CB and is given to the arithmetic circuit 44.

  In addition to the same configuration as the first differential amplifier circuit 48, the second differential amplifier circuit 49 includes an operational amplifier OP7. The non-inverting input terminal of the operational amplifier OP7 is connected to the reference potential V4. The output voltage of the operational amplifier OP6 is input to the inverting input terminal of the operational amplifier OP7. The output voltage of the operational amplifier OP7 is given to the CV conversion circuits 40 and 41 as the reference potential V1.

  The arithmetic circuit 44 obtains the displacement of the moving body 1 in the x direction based on the output voltage of the first differential amplifier circuit 48, that is, the voltage proportional to the difference between the capacitances CA and CB. For example, when the moving body 1 moves in the positive direction of the x direction, the area of the detection electrode 2A facing the moving body 1 decreases, and the area of the detection electrode 2B facing the moving body 1 increases. Accordingly, in this case, the capacitance CB is larger than the capacitance CA. Further, when the moving body 1 moves in the negative direction of the x direction, the area of the detection electrode 2A facing the moving body 1 increases, and the area of the detection electrode 2B facing the moving body 1 decreases. Therefore, in this case, the capacitance CA is larger than the capacitance CB. That is, since the difference between the capacitances CA and CB changes with the displacement of the moving body 1 in the x direction, the displacement of the moving body 1 in the x direction can be obtained from the difference between the capacitances CA and CB.

  Here, the difference between the capacitances CA and CB basically varies continuously with the displacement of the moving body 1 in the x direction, but the gap between the moving body 1 and each of the detection electrodes 2A and 2B and the ambient temperature. It also fluctuates due to changes. On the other hand, the difference between the capacitances CC and CD does not vary depending on the displacement of the movable body 1 in the x direction, but varies depending on the gap between the movable body 1 and the reference electrodes 3C and 3D and the ambient temperature. When external noise is present, the external noise is superimposed almost equally on the detection electrodes 2A and 2B and the reference electrodes 3C and 3D. In this case, it is considered that the difference between the capacitances CA and CB and the difference between the capacitances CC and CD fluctuate equally due to external noise.

  In the present embodiment, in the second differential amplifier circuit 49, the reference potential V1 is controlled so that the voltage proportional to the difference between the capacitances CC and CD matches the reference potential V4. Then, using this reference potential V1, a voltage proportional to the difference between the capacitances CA and CB is obtained in the first differential amplifier circuit. As a result, the output voltage of the first differential amplifier circuit 48 depends on the displacement of the mobile body 1 in the x direction regardless of the gap between the mobile body 1 and each of the detection electrodes 2A and 2B, changes in ambient temperature, and external noise. Depending on the voltage. In the arithmetic circuit 44, the displacement of the moving body 1 in the x direction is obtained based on the voltage.

  As described above, in the present embodiment, a pair of reference electrodes 3C and 3D having different width dimensions in the y direction are used, and the difference between the capacitances CA and CB is corrected based on the difference between the capacitances CC and CD. doing. As a result, the gap between the moving body 1 and each of the detection electrodes 2A and 2B, changes in ambient temperature, and displacement in the x direction of the moving body 1 that does not depend on external noise can be obtained. Even when only one reference electrode is used, the difference between the capacitances CA and CB can be corrected to some extent. However, as in this embodiment, using the two reference electrodes 3C and 3D and correcting using the difference between the capacitances CC and CD corrects the difference between the capacitances CA and CB more accurately. Is preferable.

  Here, in the present embodiment, the capacitances CC and CD between the movable body 1 and the movable body 1 are made different from each other by making the width dimensions in the y direction of the reference electrodes 3C and 3D different from each other. However, other configurations may be used. For example, as shown in FIG. 10A, the reference electrodes 3C and 3D have the same width dimension in the y direction, and the width dimensions in the x direction of the portions facing the reference electrodes 3C and 3D are different from each other. 1 'may be used. The moving body 1 ′ is formed in a shape in which the width dimension in the x direction at the portion facing the reference electrode 3 </ b> C is larger than the width dimension in the x direction at the portion facing the reference electrode 3 </ b> D. In this configuration, since the facing area of the reference electrode 3C with respect to the moving body 1 ′ is different from the facing area of the reference electrode 3D with respect to the moving body 1 ′, the static electrode between the reference electrodes 3C and 3D and the moving body 1 ′ is different. The electric capacities CC and CD are different from each other.

  Further, as shown in FIG. 10 (b), the movable body 1 ′ is used in which the reference electrodes 3C and 3D have the same width in the y direction and the gaps at the portions facing the reference electrodes 3C and 3D are different from each other. May be. The moving body 1 ′ is formed in a shape in which the gap at the portion facing the reference electrode 3 </ b> C is larger than the gap at the portion facing the reference electrode 3 </ b> D. Even in this configuration, the capacitances CC and CD between the reference electrodes 3C and 3D and the moving body 1 'are different from each other.

  In the first to fourth embodiments, a terminal made of a metal plate electrically connected to the processing unit 4 (processing unit 4 ′) is provided, and a signal is transmitted to an external device different from the detection device through this terminal. It is good also as a structure to output. And this terminal may be the structure welded and connected to the output electrode of the process part 4 (process part 4 '). In this configuration, the mechanical strength can be increased as compared with the configuration in which the terminal is connected to the output electrode by soldering or pressure welding. In addition, this configuration is suitable for the case where integral molding is used when configuring the detection device because the welded part is resistant to high temperatures and external stresses.

  In addition to the compensation means described in the first to fourth embodiments, for example, a capacitance C0 between the moving body 1 and the detection electrode 2 and a capacitance C0 between the moving body 1 and the reference electrode 3 are used. The displacement of the moving body 1 in the x direction may be obtained based on the ratio to '.

  In the first to fourth embodiments, the processing unit 4 (processing unit 4 ′) is part of the detection device, but the processing unit 4 (processing unit 4 ′) is incorporated in an external device different from the detection device. It may be a thing.

DESCRIPTION OF SYMBOLS 1 Mobile body 2 Detection electrode 3 Reference electrode

Claims (12)

A detection electrode disposed opposite to the moving body that moves along the one direction together with the object, and a reference electrode disposed opposite to the moving body in the vicinity of the detection electrode,
The detection electrode is formed in a shape in which the capacitance between the moving body and the moving body changes in accordance with the displacement along the one direction of the moving body,
The capacitance type detection device, wherein the reference electrode is formed in a shape in which the capacitance between the moving body and the moving body does not change depending on the displacement along the one direction.   2. The electrostatic capacitance type according to claim 1, wherein the reference electrodes are arranged on both sides of the detection electrode along a direction orthogonal to the one direction on a plane on which the reference electrodes are arranged. Detection device.   The capacitance type detection device according to claim 1, wherein the reference electrode includes a plurality of electrodes electrically independent from each other.   The capacitance type detection device according to claim 1, wherein a plurality of the reference electrodes are provided, and each of the reference electrodes has a different capacitance from the moving body.   The said detection electrode and the said reference electrode are formed in the said board | substrate inside among the multilayer substrates formed by laminating | stacking the some board | substrate which consists of a rigid board | substrate, The any one of Claim 1 thru | or 4 characterized by the above-mentioned. Capacitance type detection device.   6. The capacitance type detection device according to claim 5, wherein the rigid substrate is made of a ceramic substrate.   The capacitance type detection device according to claim 5 or 6, wherein at least a part of the multilayer substrate is integrally formed in a resin case.   8. The shield electrode connected to the same potential as that of the detection electrode is disposed at a position opposite to the movable body with the detection electrode interposed therebetween. Capacitance type detection device.   A CV conversion circuit that outputs a voltage based on a capacitance between the moving body and the detection electrode and a voltage based on a capacitance between the moving body and the reference electrode, and an output of the CV conversion circuit 9. The capacitance type detection device according to claim 1, further comprising a processing unit including an arithmetic circuit that obtains a displacement of the moving body in the one direction based on a voltage. 10.   The processing unit includes a signal processing circuit that converts an output voltage of the CV conversion circuit into a predetermined voltage and outputs the voltage, and in the signal processing circuit, an electrostatic capacitance between the moving body and the reference electrode is obtained. 10. The capacitance type detection device according to claim 9, wherein a capacitance between the movable body and the detection electrode is corrected based on the capacitance.   In the CV conversion circuit, the processing unit corrects a capacitance between the moving body and the detection electrode based on a capacitance between the moving body and the reference electrode. The capacitance type detection device according to claim 9.   It has a terminal which consists of a metal plate electrically connected with the processing part, and the terminal is welded and connected to the output electrode of the processing part. The electrostatic capacitance type detection apparatus as described.

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