JP2008157920A - Capacitance detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a capacitance detecting device capable of obtaining the output proportional to a distance to an object to be measured. <P>SOLUTION: In a condition where a reference capacity 13 and a closing switch 14 in parallel connected between an output terminal of an operational amplifier 11 and an input terminal (-), a closing switch 16 connected between a sensor electrode E1 and a potential V1 of a power supply, and a closing switch 15 connected between a sensor electrode E1 and an input terminal (-) of the operational amplifier 11 are all prepared to the capacitance detecting device, after performing switching operation putting the closing switch 14 at shut state to return to open state, a second switching operation putting the closing switch 15 at shut state to return again to open state and a third switching operation putting the closing switch 16 at shut state from open state to return again to open state are together implemented repeatedly. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a capacitance detection device.

Examples of conventional capacitance detection devices include those described in Patent Documents 1 and 2.
US Pat. No. 6,466,036 JP 2005-106665 A

  The capacitance detection device is incorporated in a system that controls opening and closing of a vehicle door such as an automobile, for example, and a detection signal of the capacitance detection device is used as a trigger when unlocking. Specifically, as a result of the user approaching the vehicle and collating the ID code between the control device mounted on the vehicle and the user, the control system transitions to the unlock permission mode. At this time, when the user touches an unlock sensor (electrode) disposed in the outside handle of the vehicle door, the capacitance detection device detects a change in the capacitance of the electrode, and a trigger signal for the opening is detected. Is output. In other words, the capacitance detection device detects the intention of unlocking from the user by a change in capacitance, and the control system outputs an unlocking trigger signal.

  In addition, the capacitance detection device is incorporated in a safety device that controls the distance between the head of the occupant and the headrest of the seat in order to reduce whipping at the time of rear-end collision of the vehicle. There is also a need to be used as a distance sensor that detects the distance between the head and the headrest using the fact that the capacitance changes according to the distance between the head and the headrest.

  In the capacitance detection device disclosed in Patent Document 1, a DC voltage source is connected to one end of a reference capacitor Cs via an open / close switch S1 as shown in FIG. 44, and a sensor electrode is connected to the other end of the reference capacitor Cs. A measured capacitor Cx having one side grounded or connected to a free space is connected via E1, an open / close switch S2 is connected between the other end of the reference capacitor Cs and the ground, and both ends of the reference capacitor Cs are connected to both ends. The open / close switch S3 is connected, and one end of the reference capacitor Cs is connected to a comparator CMP and a control circuit as a potential measuring unit for measuring the potential of the one end.

  As shown in FIG. 45, this capacitance detection device first closes the switch S2 and the switch S3 to discharge the charges of the reference capacitor Cs and the measured capacitor Cx. Next, the switch S1 is closed to charge the reference capacitor Cs and the measured capacitor Cx with a DC voltage source, and the potential of the reference capacitor is increased to a voltage determined by the capacitance ratio of the reference capacitor Cs and the measured capacitor Cx. Later, the switch S1 is opened, the switch S2 is closed, the other end of the reference capacitor Cs is grounded to discharge the charge of the capacitor Cx to be measured, and the operation of measuring the potential of the reference capacitor Cs by the control unit is repeated. The number of times until the potential of the reference capacitor Cs rises to the set potential is counted. The presence or absence of a change in the capacitance value of the measured capacitance Cx is detected by increasing or decreasing the number of times until the potential of the reference capacitance Cs rises to the set potential.

  Patent Document 1 also describes a capacitance detection device that detects the presence or absence of changes in two measured capacitances. In this capacitance detection device, sensor electrodes are connected to both ends of a reference capacitor Cs, and two measured capacitors Cx1 and Cx2 having one side connected to ground or free space are connected to each sensor electrode. One end of the reference capacitor Cs is connected to a DC voltage source via an open / close switch S1 and grounded via an open / close switch S2. The other end of the reference capacitor Cs is connected to a DC voltage source via an open / close switch S3 and grounded via an open / close switch S4. In the capacitance detection device, the open / close switches S1 to S4 are operated, and the potentials at both ends of the reference capacitor Cs are measured by the two potential measuring units to determine whether there are changes in the two measured capacitances Cx1 and Cx2. Detected.

  Further, in the capacitance detection device disclosed in Patent Document 2, one end of a reference capacitor Cs having an open / close switch S1 connected between both ends thereof is connected to a DC voltage source, and the other end of the reference capacitor Cs is connected to the open / close switch S2. Is connected to one end of the measured capacitance Cx, the other end of the measured capacitance Cx is grounded, and an open / close switch S3 is connected between both ends of the measured capacitance Cx. In this capacitance detection device, after performing the first switch operation for closing and opening the open / close switch S1, the second switch operation for opening and closing the open / close switch S2 and the open / close switch S3 are performed. The third switch operation of closing and returning to the open is alternately repeated, and the static capacitance of the measured capacitor Cx is determined based on the number of times of the second switch operation until the potential of the other end of the reference capacitor Cs changes to a predetermined potential. A change in the capacitance value is detected.

However, in the above conventional example, the process of connecting the measured capacitor to the charged reference capacitor is repeated and the potential of the reference capacitor is measured. Therefore, the potential is divided by the sum of the measured capacitor and the reference capacitor. The value obtained by multiplying the measured value by the number of connections of the measured capacity, that is, a value obtained by dividing the reference capacity by the sum of the measured capacity and the reference capacity, is a linear function of an exponential function with the number of connections as an index. Therefore, if the value of the capacitance formed by the sensor electrode that is the capacitance to be measured is small and the amount of change is small, the accuracy of capacitance detection is low. In addition, when the capacitance detection device is used as a distance sensor for measuring the distance between sensor electrodes, the potential of the reference capacitance is a linear function of the exponential function described above, so that the output is proportional to the distance with a simple circuit. It was difficult.
The present invention has been made in view of the above situation, and an object of the present invention is to provide a capacitance detection device that can obtain an output proportional to the distance of a sensor electrode with a simple circuit.

In order to achieve the above object, a capacitance detection device according to a first aspect of the present invention has an inverting input terminal, a non-inverting input terminal, and an output terminal, and the non-inverting input terminal has a first fixed state. A first differential amplifier to which a potential is input;
A first reference capacitor having one electrode connected to the inverting input terminal of the first differential amplifier and the other electrode connected to the output terminal of the first differential amplifier;
A first open / close switch having one end connected to the inverting input terminal of the first differential amplifier and the other end connected to the output terminal of the first differential amplifier;
A second open / close switch having one end connected to the inverting input terminal of the first differential amplifier;
A third open / close switch having one end connected to the other end of the second open / close switch and the other end connected to a first power supply potential;
A first sensor electrode which is connected to the other end of the second open / close switch and forms a capacitor which faces a substantially constant potential conductor and exhibits a capacitance according to the distance from the conductor; ,
A second switch operation for closing the first open / close switch and then opening the first open / close switch and then returning the open / close switch to the open state after closing the second open / close switch; Switch control means for alternately repeating the third switch operation for returning the open state to the open state after closing the third open / close switch;
A comparator that has one input terminal connected to the output terminal of the first differential amplifier and compares the output voltage of the first differential amplifier with the voltage input to the other input terminal;
Counting means for counting the number of times the second switch operation is repeated;
Based on the number of times of the second switch operation counted by the counting means until the level of the input voltage at both input terminals of the comparator is inverted, the static between the first sensor electrode and the conductor is determined. Determining means for determining a change in electric capacity;
It is characterized by providing.

  The voltage input to the other input terminal of the comparator may be out of phase with the voltage input to the one input terminal of the comparator.

Furthermore, a fourth open / close switch having one end connected to the inverting input terminal of the first differential amplifier;
A first correction capacitor having one electrode connected to the other end of the fourth open / close switch and the other electrode connected to a first correction potential;
A fifth open / close switch having one end connected to the other end of the fourth open / close switch and the other end connected to the first correction potential;
The switch control means opens and closes the fourth open / close switch at the same timing as the second open / close switch, and opens and closes the fifth open / close switch at the same timing as the third open / close switch. Good.

In addition, the surface of the first sensor electrode other than the surface facing the conductor and at least a part of the wiring connecting the first sensor electrode and the second and third open / close switches are surrounded. A first shield member;
A first potential supply circuit that maintains the first shield member at the first fixed potential when at least the second opening / closing switch transitions from a closed state to an open state;
A second potential supply circuit for maintaining the first shield member at the first power supply potential when at least the third opening / closing switch transitions from a closed state to an open state;
May be provided.

In this case, a first current detection circuit connected between the first potential supply circuit and the first shield member;
First potential applying means for applying a potential different from the first power supply potential to the first shield member during a predetermined period when the third open / close switch is closed;
May be provided.

A surface of the first sensor electrode other than the surface facing the conductor, wiring connecting the first sensor electrode and the second and third on / off switches, and the first shield member; A first outer shield member surrounding at least a part of
The first outer shield member may be set to a constant potential.

In order to achieve the above object, a capacitance detection device according to a second aspect of the present invention has an inverting input terminal, a non-inverting input terminal, and an output terminal, and the non-inverting input terminal has a first fixed state. A first differential amplifier to which a potential is input;
A first reference capacitor having one electrode connected to the inverting input terminal of the first differential amplifier and the other electrode connected to the output terminal of the first differential amplifier;
A first open / close switch having one end connected to the inverting input terminal of the first differential amplifier and the other end connected to the output terminal of the first differential amplifier;
A second open / close switch having one end connected to the inverting input terminal of the first differential amplifier;
A third open / close switch having one end connected to the other end of the second open / close switch and the other end connected to a first power supply potential;
A first sensor electrode which is connected to the other end of the second open / close switch and forms a capacitor which faces a substantially constant potential conductor and exhibits a capacitance according to the distance from the conductor; ,
A second differential amplifier having an inverting input terminal, a non-inverting input terminal, and an output terminal, the second fixed potential being input to the non-inverting input terminal;
A second reference capacitor having one electrode connected to the inverting input terminal of the second differential amplifier and the other electrode connected to the output terminal of the second differential amplifier;
A fourth open / close switch having one end connected to the inverting input terminal of the second differential amplifier and the other end connected to the output terminal of the second differential amplifier;
A fifth open / close switch having one end connected to the inverting input terminal of the second differential amplifier;
A sixth open / close switch having one end connected to the other end of the fifth open / close switch and the other end connected to a second power supply potential;
A second sensor electrode which is connected to the other end of the fifth open / close switch and forms a capacitor which faces the conductor and exhibits a capacitance according to the distance from the conductor;
After performing the first switch operation for opening the first open / close switch and the fourth open / close switch after closing the first open / close switch and the fourth open / close switch, the second open / close switch and the fifth open / close switch are closed. Switch control means for alternately repeating a second switch operation for returning to the open state and a third switch operation for returning the open state to the open state after closing the third open / close switch and the sixth open / close switch;
One input terminal is connected to the output terminal of the first differential amplifier and the other input terminal is connected to the output terminal of the second differential amplifier, and the output voltage of the first differential amplifier is A comparator for comparing the output voltage of the second differential amplifier;
Counting means for counting the number of times the second switch operation is repeated;
Based on the number of times of the second switch operation counted by the counting means until the level of the input voltage at both input terminals of the comparator is inverted, at least one of the first sensor electrode and the second sensor electrode. Determining means for determining a change in capacitance between one and the conductor;
It is characterized by providing.

A seventh open / close switch having one end connected to the inverting input terminal of the first differential amplifier;
A first correction capacitor having one electrode connected to the other end of the seventh open / close switch and the other electrode connected to a first correction potential;
An eighth open / close switch having one end connected to the other end of the seventh open / close switch and the other end connected to the first correction potential;
A ninth open / close switch having one end connected to the inverting input terminal of the second differential amplifier;
A second correction capacitor having one electrode connected to the other end of the ninth open / close switch and the other electrode connected to a second correction potential;
A tenth open / close switch having one end connected to the other end of the ninth open / close switch and the other end connected to the second correction potential;
The switch control means opens and closes the seventh open / close switch and the ninth open / close switch at the same timing as the second open / close switch and the fifth open / close switch, and the eighth open / close switch and the tenth open / close switch. May be opened and closed at the same timing as the third open / close switch and the sixth open / close switch.

In addition, the surface of the first sensor electrode other than the surface facing the conductor and at least a part of the wiring connecting the first sensor electrode and the second and third open / close switches are surrounded. A first shield member;
A first potential supply circuit that maintains the first shield member at the first fixed potential when at least the second opening / closing switch transitions from a closed state to an open state;
A second potential supply circuit for maintaining the first shield member at the first power supply potential when at least the third opening / closing switch transitions from a closed state to an open state;
A second surrounding the surface of the second sensor electrode other than the surface facing the conductor and at least a part of the wiring connecting the second sensor electrode and the fifth and sixth open / close switches. A shielding member of
A third potential supply circuit that maintains the second shield member at the second fixed potential when at least the fifth open / close switch transitions from a closed state to an open state;
A fourth potential supply circuit for maintaining the second shield member at the second power supply potential when at least the sixth open / close switch transits from a closed state to an open state;
May be provided.

In this case, a first current detection circuit connected between the first potential supply circuit and the first shield member;
First potential applying means for applying a potential different from the first power supply potential to the first shield member during a predetermined period when the third open / close switch is closed;
A second current detection circuit connected between the third potential supply circuit and the second shield member;
Second potential applying means for applying a potential different from the second power supply potential to the second shield member during a predetermined period when the fourth open / close switch is closed;
May be provided.

A surface of the first sensor electrode other than the surface facing the conductor, wiring connecting the first sensor electrode and the second and third on / off switches, and the first shield member; A first outer shield member surrounding at least a portion of
At least one of a surface of the second sensor electrode other than the surface facing the conductor, a wiring connecting the second sensor electrode and the fifth and sixth open / close switches, and at least the second shield member A second outer shield member surrounding the part,
The first outer shield member and the second outer shield member may be set to an arbitrary constant potential.

  Furthermore, the areas of the first sensor electrode and the second sensor electrode may be equal, and the center of gravity of the first sensor electrode and the center of gravity of the second sensor electrode may substantially coincide.

  In this case, the first sensor electrode and the second sensor electrode may be arranged symmetrically with respect to two or more planes passing through the center of gravity.

  ADVANTAGE OF THE INVENTION According to this invention, even when it uses as a distance sensor, the electrostatic capacitance detection apparatus which can obtain the output proportional to distance with a simple circuit structure is realizable.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[First Embodiment]
FIG. 1 is a circuit diagram showing a capacitance detection device 10 according to the first embodiment of the present invention.
FIG. 2 is a diagram showing a part A of FIG.

  The capacitance detection device 10 includes a first differential amplifier (hereinafter referred to as an operational amplifier) 11, a comparator 12 as a comparator, a first reference capacitor 13, a first opening / closing switch 14, and a second Open / close switch 15, third open / close switch 16, first sensor electrode E 1, and controller 17. The control unit 17 determines whether or not the output level of the comparator 12 has changed, the switch control unit 17a for controlling the switching of the open / close switches 14 to 16, the count unit 17b for counting the number of on / off times of the open / close switch 15. And determining means 17c for outputting an output signal corresponding to the number counted by the counting means 17b until the output level of the comparator 22 changes.

  The output terminal of the operational amplifier 11 is connected to one electrode of the reference capacitor 13, one end of the open / close switch 14, and one input terminal (−) of the comparator 12. The other electrode of the reference capacitor 13, the other end of the open / close switch 14, and one end of the open / close switch 15 are connected to the inverting input terminal (−) of the operational amplifier 11. The other end of the open / close switch 15 is connected to the other end of the open / close switch 16 whose one end is connected to the first power supply potential V1 and the sensor electrode E1. The non-inverting input terminal (+) of the operational amplifier 11 is connected to the first fixed potential V3. The potential Vin + of the other input terminal (+) of the comparator 12 is fixed to the power supply potential V 4, and the output terminal of the comparator 12 is connected to the control unit 17.

  As shown in FIG. 2, the sensor electrode E1 forms a capacitor between the sensor E1 and the conductor E0 facing the conductor E0 having a substantially constant potential. The sensor electrode E1 is one electrode of the capacitor. The capacity of this capacitor is the measured capacity Cx11.

Next, the operation of the capacitance detection device of FIG. 1 will be described with reference to FIG.
3A to 3F are timing charts for explaining the operation of FIG. In FIG. 3, the relationship between the heights of the potentials V1, V3, and V4 is V1>V3> V4, but the relationship between the heights of the potentials V1, V3, and V4 may be V1 <V3 <V4.

FIG. 3 shows an initial state in which the potential VE1 is charged to the power supply potential V1, and the potential Vin− of the inverting input terminal of the comparator 12 is lower than the potential V4.
Under the control of the control unit 17, after performing the first switch operation (FIG. 3A) for returning the open / close switch 14 from the open state to the closed state for a predetermined period, the open / close switch 15 is changed from the open state to the predetermined period. The second switch operation (FIG. 3 (b)) for returning to the open state again after closing, and the third switch operation (FIG. 3 (b) for returning the open / close switch 16 from the open state to the closed state for a predetermined period. c)) is repeated.

  By the first switch operation, both electrodes of the reference capacitor 13 are short-circuited, and the potential Vin− of the output terminal of the operational amplifier 11 and the inverting input terminal of the comparator 12 exceeds the potential V4 and rises to the potential V3 (FIG. 3 (e )), The output signal Vout of the comparator 12 transits from a high level to a low level (FIG. 3 (f)).

  By the second switch operation, the reference capacitor 13 is charged and the potential Vin− is lowered by the charge that has been charged in the sensor electrode E1 so far. Although the potential VE1 of the sensor electrode E1 is lowered by the second switching operation, the potential VE1 of the sensor electrode E1 becomes the power supply potential V1 again by the third switch operation.

  By repeating the second switch operation and the third switch operation, the potential Vin− of the inverting input terminal of the comparator 12 decreases according to the number of repetitions. When the potential Vin− of the inverting input terminal of the comparator 12 becomes equal to or lower than the potential V4, the output signal of the comparator 12 transitions to a high level. The control unit 17 counts the number of times of the second switch operation repeatedly performed until the output signal Vout of the comparator 12 transitions, and outputs a calculation result using this as a function.

Here, the parallel circuit of the reference capacitor 13 and the open / close switch 14 becomes a negative feedback impedance of the operational amplifier 11, and the potential of the output terminal of the operational amplifier 11, that is, the potential Vin− of the inverting input terminal of the comparator 12 is generated by the first switch operation. The same potential as the fixed potential V3. When the second switch operation and the third switch operation are repeated, the potential Vin− of the inverting input terminal of the comparator 12 is equal to the number n of repetitions of the second switch operation and the capacitance of the capacitor having the sensor electrode E1 as one electrode. From the relationship between the measurement capacitor Cx11, the capacitance value Cs1 of the reference capacitor 13, and the potentials V1 and V3,
Vin− = V3−n × (V1−V3) × Cx11 / Cs1 (1)
And changes in proportion to the number of times n of the second switch operation.

From the above equation, if the number n0 of second switch operations until the level of the output signal of the comparator 12 transitions is sufficiently large, the measured capacitance Cx11 is Cx11 × (V1−V3) × n0≈Cs1 × (V3− From V4), it can be expressed by the following equation.
Cx11 = (V3-V4) / (V1-V4) × Cs1 / n0 (2)

  Assuming that the capacitor whose sensor electrode E1 is one electrode is a flat plate capacitor, the distance d to the target conductor E0 and the measured capacitance Cx11 are in an inversely proportional relationship. Since the measurement capacitance Cx11 and the number of times n0 are in an inversely proportional relationship, the distance d and the number of times n0 are in a proportional relationship, and can be used directly as a distance sensor without changing the configuration of the capacitance detection device 10 in FIG. The output of the capacitance detection device 10 can be directly used as distance information.

[Second Embodiment]
In the first embodiment described above, the fixed power supply potential V4 is applied to the other input terminal (+) of the comparator 12. However, the phase is opposite to the potential Vin− of the one input terminal (−) of the comparator 12. Alternatively, a potential Vin + that changes to may be input. One example is shown in the second embodiment.

FIG. 4 is a circuit diagram showing a capacitance detection device 20 according to the second embodiment of the present invention.
FIG. 5 is a diagram showing a part A of the capacitance detection device 20 of FIG.

  The capacitance detection device 20 includes a first operational amplifier 21. The output terminal of the operational amplifier 21 is connected to one input terminal (−) of the comparator 22, and the output terminal of the operational amplifier 21 includes one electrode of the first reference capacitor 23 and one end of the first opening / closing switch 24. Is connected. The other electrode of the reference capacitor 23, the other end of the open / close switch 24, and one end of the second open / close switch 25 are connected to the inverting input terminal of the operational amplifier 21. The other end of the open / close switch 25 is connected to the other end of the third open / close switch 26 whose one end is connected to the first power supply potential V1 and the first sensor electrode E1. The non-inverting input terminal (+) of the operational amplifier 21 is connected to the first fixed potential V3.

  The capacitance detection device 20 is further provided with a second operational amplifier 31. One electrode of the second reference capacitor 33 and one end of the fourth open / close switch 34 are connected to the output terminal of the operational amplifier 31, and the other input terminal (+) of the comparator 22 is connected. The other electrode of the reference capacitor 33, the other end of the open / close switch 34, and one end of the fifth open / close switch 35 are connected to the inverting input terminal (−) of the operational amplifier 31.

  The other end of the opening / closing switch 35 is connected to the other end of the sixth opening / closing switch 36 whose one end is connected to the second power supply potential V2 and the second sensor electrode E2. The non-inverting input terminal (+) of the operational amplifier 31 is connected to the second fixed potential V5. The output terminal of the comparator 22 is connected to the control unit 37. The control unit 37 includes a switch control unit 37a that controls switching of the open / close switches 25 to 26 and 34 to 36, a count unit 37b that counts the number of on / off times of the open / close switches 25 and 35, and the output level of the comparator 22 has changed. Determination means 37c for outputting an output signal corresponding to the number counted by the counting means 37b until the output level of the comparator 22 changes.

As shown in FIG. 5, the sensor electrodes E1 and E2 are opposite to the conductor E0 to be detected and form capacitors having measured capacitances Cx11 and Cx21 between the conductor E0 and the sensor electrodes E1 and E2, respectively. Becomes one electrode of each capacitor. The sensor electrodes E1 and E2 are arranged close to each other. Cx0 in FIG. 5 is a parasitic capacitance formed between the sensor electrodes E1 and E2.
The relationship between the heights of the potentials V1, V2, V3, and V5 may be V1>V3>V5> V2 or V1 <V3 <V5 <V2.

Next, the operation of the capacitance detection device 20 will be described with reference to FIG.
6A to 6G are timing charts for explaining the operation of the capacitance detection device 20 of FIG. As an initial state, the potential VE1 of the sensor electrode E1 is charged to the power supply potential V1, and the potential VE2 of the sensor electrode E2 is shown to be charged to the power supply potential V2.

  The control unit 37 performs the first switch operation to return the open / close switches 24 and 34 from the open state to the closed state for a predetermined period and then return the open / close switches 25 and 35 from the open state to the closed state for a predetermined period. The second switch operation for returning to the open state and the third switch operation for returning the open / close switches 26 and 36 from the open state to the closed state for a predetermined period are repeated.

  By the first switch operation (FIG. 6A), the reference capacitors 23 and 33 are discharged, the potential Vin− of the output terminal of the operational amplifier 21, that is, one input terminal (−) of the comparator 22 rises, and the operational amplifier 31. The potential Vin + of the other input terminal (+) of the comparator 22, which is the output terminal of, drops (FIG. 6 (e)). When the levels of the potential Vin− and the potential Vin + are reversed, the output signal Vout of the comparator 22 transitions from, for example, a high level to a low level (FIG. 6G).

  The reference capacitors 23 and 33 are charged by the charges charged in the sensor electrodes E1 and E2 (FIGS. 6D and 6F) by the second switch operation (FIG. 6B), and the comparators The potential Vin− of one input terminal (−) of 22 decreases, and the potential Vin + of the other input terminal (+) increases. By the third switch operation (FIG. 6C), the potential VE1 of the sensor electrode E1 becomes the power supply potential V1 again, and the potential VE2 of the sensor electrode E2 becomes the power supply potential V2 again.

  By repeating the second switch operation and the third switch operation, the level of the potential Vin− of the input terminal (−) of the comparator 22 and the level of the potential Vin + of the input terminal (+) are inverted, and the output signal of the comparator 22 is inverted. The level of Vout transitions and becomes high again.

  The control unit 37 counts the number of times of the second switch operation repeatedly performed until the output signal Vout of the comparator 22 transitions to a high level, and outputs a calculation result using this as a function.

  As described above, in the present embodiment, the operational amplifier 21, the reference capacitor 23, the open / close switches 24 to 26, and the sensor electrode E1 are the operational amplifier 11, the reference capacitor 13, the open / close switches 14 to 16 and the sensor electrode E1 of the first embodiment. Works as well. The operational amplifier 21, the reference capacitor 23, the open / close switches 24 to 26, and the sensor electrode E1 generate a potential Vin−, whereas the operational amplifier 31, the reference capacitor 33, the open / close switches 34 to 36, and the sensor electrode E2 are reversed. A phase potential Vin + is generated and applied to the comparator 22.

  Here, the change of the potential Vin− is proportional to the number of times of the second switch operation and substantially proportional to the measured capacitance Cx11, and the change of the potential Vin + is also proportional to the number of times of the second switch operation and the measured capacitance Cx21. Is almost proportional to Since the measured capacitances Cx11 and Cx21 are inversely proportional to the distance d between the sensor electrodes E1 and E2 and the conductor E0, the number counted by the counting means before the output signal Vout of the comparator 22 transits to a high level is also the distance d. Is a function of Therefore, when the capacitance detection device 20 is used as a distance sensor, the output of the capacitance detection device 20 can be used as distance information.

  In addition, charges corresponding to the measured capacitors Cx11 and Cx21 are accumulated in the reference capacitors 23 and 33, and a signal based on the potential difference between both ends of the reference capacitors 23 and 33 is compared by the comparator 22 and the static capacitance of the measured capacitors 23 and 33 is measured. In the configuration for detecting the capacitance, the ratio SE1 / Cs2 of the area SE1 of the sensor electrode E1 and the capacitance Cs2 of the first reference capacitor 23, and the area SE2 of the sensor electrode E2 and the capacitance Cs3 of the second reference capacitor 33 are included. By making the ratio SE2 / Cs3 equal, the influence of electromagnetic disturbance can be suppressed, and the area SE1 of the sensor electrode E1, the potential fluctuation width SE1 (V1-V3) of the sensor electrode E1, the area SE2 of the sensor electrode E2, and the sensor electrode E2 The generation of radio noise can also be suppressed by equalizing the potential fluctuation width SE1 (V5-V2).

  For example, the influence of the electromagnetic disturbance input to the comparator 22 can be suppressed by making the areas of the sensor electrodes E1 and E2 equal and the capacitances of the first reference capacitor 23 and the second reference capacitor 33 equal. Furthermore, by setting V1−V3 = V5−V2, the generation of radio noise at the sensor electrodes E1 and E2 can be suppressed.

[Third Embodiment]
FIG. 7 is a circuit diagram showing a capacitance detection device 40 according to the third embodiment of the present invention. Elements common to those in FIG. 1 are denoted by common reference numerals.

  The capacitance detection device 40 includes a first operational amplifier 11, a comparator 12, a first reference capacitor 13, a first open / close switch 14, and a second switch connected in the same manner as in the first embodiment. An open / close switch 15, a third open / close switch 16, a first sensor electrode E 1, and a control unit 17 are provided.

The capacitance detection device 40 is further provided with a seventh open / close switch 41, an eighth open / close switch 42, and a first correction capacitor 43.
One end of the open / close switch 41 is connected to the inverting input terminal (−) of the operational amplifier 11, and the other end of the open / close switch 41 is connected to one electrode of the correction capacitor 43 and one end of the open / close switch 42. The other end of the open / close switch 42 and the other electrode of the correction capacitor 43 are connected to the first correction potential V6. Note that the other electrode of the correction capacitor 43 may be connected to a constant potential other than the correction potential V6.

  The control unit 17 controls switching of the open / close 41 and 42 in addition to the open / close switches 14 to 16. Here, the open / close switch 41 opens and closes at the same timing as the open / close switch 15, and the open / close switch 42 opens and closes at the same timing as the open / close switch 16 under the control of the control unit 17.

The relationship between the power supply potentials V1 and V3 and the correction potential V6 is V1>V3> V6 or V1 <V3 <V6.
At least one of the capacitance value Cc1 or the correction potential V6 of the correction capacitor 43 is adjustable, and the following is applied to the parasitic capacitance Cα1 parasitic on the sensor electrode E1 and the wiring connecting the sensor electrode E1 and the open / close switches 15 and 16. The capacitance value Cc1 and the correction potential V6 are adjusted so as to satisfy the equation (3).
(V1-V3) Cα1 = (V3-V6) Cc1 (3)

  The electrostatic capacitance detection device 40 performs the first switch operation to return the open / close switch 14 from the open state to the closed state for a predetermined period under the control of the control unit 17, and then open the open / close switches 15 and 41. The second switch operation for returning from the state to the closed state for a predetermined period and returning to the open state again, and the third switch operation for returning the open / close switches 16 and 42 from the open state to the closed state for a predetermined period and returning to the open state are repeated.

  When the second switch operation and the third switch operation are repeated, the capacitor having the sensor electrode E1 as one electrode is charged by the third switch operation, and at the same time, the parasitic capacitance Cα1 is charged. Then, the capacitor having the sensor electrode E1 as one electrode and the parasitic capacitance Cα1 are connected to the inverting input terminal (−) of the operational amplifier 11 and discharged by the second switch operation.

  On the other hand, the correction capacitor 43 is discharged when the third switch is operated, and is connected to the inverting input terminal (−) of the operational amplifier 11 when the second switch is operated. Thus, one cycle of the opening / closing operation of the four switches, that is, the closing operation of the opening / closing switch 16 and the opening / closing switch 42 and the opening operation after a certain period of time when the switches 16 and 42 are closed, followed by the opening / closing switch 15 and opening / closing. After the closing operation of the switch 41 and the opening operation after a certain period of time in the closed state of the switches 15 and 41 are performed, the reference capacitor 13 is charged with the charge expressed by the equation (4).

Here, since the capacitance value Cc1 of the correction capacitor 43 is adjusted by the equation (3), a charge corresponding to the charge that has been charged in the parasitic capacitance Cα is charged. Therefore, from the relational expression between Cα1 and Cc1 in the expression (3), the reference capacitor 13 has the charge of (V1−V3) Cx11, that is, the charge discharged from the capacitor having the sensor electrode E1 as one electrode. It is charged with the corresponding charge. That is, the influence of the parasitic capacitance Cα1 in the reference capacitor 13 can be eliminated, and the influence of the parasitic capacitance Cα1 on the output signal of the operational amplifier 11, that is, the potential Vin− of the inverting input terminal (−) of the comparator 12 can be eliminated.
(V1-V3) (Cx11 + Cα1) + (V6-V3) Cc1 (4)

  By repeating the second switch operation and the third switch operation, the potential Vin− of the inverting input terminal (−) of the comparator 12 decreases according to the number of repetitions. When the potential Vin− of the inverting input terminal of the comparator 12 becomes equal to or lower than the power supply potential V4, the output signal of the comparator 12 transits to a high level. The control unit 17 counts the number of times of the second switch operation repeatedly performed until the output signal Vout of the comparator 12 transits to a high level, and outputs a calculation result using this as a function.

  As described above, the capacitance detection device 40 of the third embodiment includes the operational amplifier 11, the comparator 12, the reference capacitor 13, the open / close switches 14 to 16, and the sensor electrode E1, and includes the first electrode. Since the open / close switches 14 to 16 are opened and closed in the same manner as in the embodiment, conversion to distance information when used as a distance sensor is simple as in the capacitance detection device 10 of the first embodiment. Further, the open / close switches 41 and 42 and the correction capacitor 43 are provided. The open / close switch 41 is opened / closed at the same timing as the open / close switch 15, and the open / close switch 42 is opened / closed at the same timing as the open / close switch 16, thereby eliminating the influence of the parasitic capacitance Cα1. This can improve the accuracy of capacitance detection.

[Fourth Embodiment]
FIG. 8 is a circuit diagram showing a capacitance detection device 50 according to the fourth embodiment of the present invention. Elements common to those in FIG. 4 are denoted by common reference numerals.
The capacitance detection device 50 includes first and second operational amplifiers 21 and 31, a comparator 22, first and second reference capacitors 23 and 33, and first to sixth open / close switches 24, 25 and 26. , 34, 35, 36, first and second sensor electrodes E1, E2, and a control unit 37, which are connected in the same manner as in FIG. 4 of the second embodiment.

  The capacitance detection device 50 further includes a seventh opening / closing switch 51, an eighth opening / closing switch 52, a first correction capacitor 53, a ninth opening / closing switch 54, a tenth opening / closing switch 55, and a second opening / closing switch. A correction capacitor 56 is provided.

  One end of the open / close switch 51 is connected to the inverting input terminal (−) of the operational amplifier 21, and the other end of the open / close switch 51 is connected to one electrode of the correction capacitor 53 and one end of the open / close switch 52. The other end of the open / close switch 52 and the other electrode of the correction capacitor 53 are connected to the first correction potential V6. Note that the other electrode of the correction capacitor 53 may be connected to a constant potential other than the correction potential V6.

One end of the open / close switch 54 is connected to the inverting input terminal (−) of the operational amplifier 31, and the other end of the open / close switch 54 is connected to one electrode of the correction capacitor 56 and one end of the open / close switch 55. The other end of the open / close switch 55 and the other electrode of the correction capacitor 56 are connected to the second correction potential V7. Note that the other electrode of the correction capacitor 56 may be connected to a constant potential other than the correction potential V7.
The relationship between the potentials V1 to V5 and the heights of the potentials V6 and V7 is that V1>V3>V5> V2 and V3> V6 and V7> V5.

  At least one of the capacitance value Cc1 and the correction potential V6 of the correction capacitor 53 can be adjusted, and at least one of the capacitance value Cc2 and the correction potential V7 of the correction capacitor 56 can be adjusted. The capacitance value is such that (V1−V3) Cα1 = (V3−V6) Cc1 with respect to the parasitic capacitance Cα1 parasitic on the sensor electrode E1 and the wiring connecting the sensor electrode E1 and the open / close switches 25 and 26. Cc1 and the correction potential V6 are adjusted in advance.

The capacitance value is such that (V5−V2) Cα2 = (V7−V5) Cc2 with respect to the parasitic capacitance Cα2 parasitic on the sensor electrode E2 and the wiring connecting the sensor electrode E2 and the open / close switches 54 and 55. Cc2 and the correction potential V5 are adjusted in advance.
The control unit 37 controls switching of the open / close switches 51, 52, 54, 55 in addition to the open / close switches 24-26, 34-36. Here, the open / close switches 51, 54 are opened / closed at the same timing as the open / close switches 25, 35, and the open / close switches 52, 55 are opened / closed at the same timing as the open / close switches 26, 36 as controlled by the control unit 37.

  Similar to the capacitance detection device 20 of the second embodiment, this capacitance detection device 50 is opened by opening and closing the open / close switches 24 and 34 from the open state for a predetermined period under the control of the control unit 37. After performing the first switch operation for returning, the second switch operation for returning the open / close switches 25, 35, 51, and 54 from the open state to the closed state for a predetermined period and the open / close switches 26, 36, 52, 55 is repeatedly performed with the third switch operation to return the open state from the open state to the closed state for a predetermined period.

  When the second switch operation and the third switch operation are repeated, the capacitors having the sensor electrodes E1, E2 as one electrode are charged by the third switch operation, and at the same time, the parasitic capacitances Cα1, Cα2 are charged. Then, the capacitor having the sensor electrodes E1 and E2 as one electrode and the parasitic capacitances Cα1 and Cα2 are connected to the inverting input terminals (−) of the operational amplifiers 21 and 31, respectively, and discharged by the second switch operation.

  On the other hand, the correction capacitors 53 and 56 are discharged when the third switch is operated, and are connected to the inverting input terminals (−) of the operational amplifiers 21 and 31 when the second switch is operated. In this way, after one cycle of opening / closing operation of the switches including one second switch operation and one third switch operation is performed, the charge indicated by the following equation (5) is stored in the reference capacitor 23. However, the reference capacitor 33 is charged with the charge represented by the following equation (6). Here, the capacitance value Cc1 of the correction capacitor 53 is adjusted by the formula of (V1-V3) Cα1 = (V3-V6) Cc1 as described above, and the capacitance value Cc2 of the correction capacitor 56 is (V5-V2) Cα2 = Since (V7−V5) Cc2 is adjusted, the charge corresponding to the charge that has been charged in the parasitic capacitances Cα1 and Cα2 is charged.

Therefore, from the relationship between the equations Cα1 and Cc1 and the relationship between Cα2 and Cc2, the reference capacitor 23 has a charge of (V1−V3) Cx11, and the reference capacitor 33 has a charge of (V2−V5) Cx21. That is, it is charged with a charge corresponding to the charge discharged from each capacitor having the sensor electrodes E1 and E2 as one electrode. That is, the influence of the parasitic capacitances Cα1 and Cα2 in the reference capacitors 23 and 33 can be eliminated, respectively, and the influence of the parasitic capacitances Cα1 and Cα2 on the output signals of the operational amplifiers 21 and 31, that is, the potentials of the input terminals of the comparator 37 is removed. it can.
(V1-V3) (Cx11 + Cα1) + (V6-V3) Cc1 (5)
(V2−V5) (Cx21 + Cα2) + (V7−V5) Cc2 (6)

  The control unit 37 counts the number of times of the second switch operation repeatedly performed until the output signal Vout of the comparator 37 transitions to a high level, and outputs a calculation result using this as a function.

  The electrostatic capacitance detection device 50 is provided with opening / closing switches 51, 52, 54, 55 and correction capacitors 53, 56, and (V1-V3) Cα1 with respect to the electrostatic capacitance detection device 20 of the second embodiment of FIG. = (V3−V6) Cc1 and (V5−V2) Cα2 = (V7−V5) Cc2 is adjusted so that Cc1 or V6, Cc2 or V7 is adjusted, so that the influence of the parasitic capacitances Cα1 and Cα2 can be eliminated. The accuracy of capacitance detection is improved.

  Further, like the capacitance detection device 20 of the second embodiment, the number of cycles in which the switches are opened and closed between the time when the output of the comparator 22 changes to a low level and the time when the output changes to a high level. In addition to being approximately proportional to the distance to the constant potential conductor E0, the influence of the parasitic capacitances Cα1 and Cα2 can be eliminated, so that conversion to distance information when used as a distance sensor can be performed with high accuracy.

    Similarly to the capacitance detection device 20 of the second embodiment, the ratio SE1 / Cs2 of the area SE1 of the sensor electrode E1 and the capacity Cs2 of the first reference capacitor 23, the area SE2 of the sensor electrode E2, and the second By making the ratio SE2 / Cs3 of the capacitance Cs3 of the reference capacitance 33 equal, the influence of electromagnetic disturbance can be suppressed, and the area SE1 of the sensor electrode E1, the potential fluctuation width SE1 (V1-V3) of the sensor electrode E1, and the sensor electrode Generation of radio noise can be suppressed by making the area SE2 of E2 equal to the potential fluctuation width SE1 (V4-V2) of the sensor electrode E2.

[Fifth Embodiment]
In the third and fourth embodiments described above, the influence of the parasitic capacitances Cα1 and Cα2 parasitic on the wiring is eliminated using the correction capacitors 43, 53, and 56, and the capacitance detection accuracy is improved. The influence of the parasitic capacitances Cα1 and Cα2 can be eliminated by using the member and the open / close switch. In the tenth embodiment continued from the fifth embodiment, a capacitance detection device using a shield member will be described.

9, 10 and 11 are circuit diagrams showing a capacitance detecting device 60 according to the fifth embodiment of the present invention. Elements common to those in FIG. 1 are denoted by common reference numerals. Yes.
FIG. 12 is an explanatory diagram schematically showing the periphery of the sensor electrode E1 of the A part in FIGS.

  The capacitance detection device 60 includes a first operational amplifier 11, a comparator 12, a first reference capacitor 13, a first opening / closing switch 14, and a second opening / closing that are connected in the same manner as in the first embodiment. A switch 15, a third open / close switch 16, a first sensor electrode E <b> 1 that forms a capacitor facing the conductor E <b> 0 having a substantially constant potential, and a control unit 17 are provided.

  Unlike the first embodiment, the capacitance detection device 60 is provided with a first shield member Es1. The shield member Es1 surrounds a surface other than the electrode surface facing the conductor E0 of the sensor electrode E1 with a predetermined insulating layer, and also surrounds the wiring connecting the sensor electrode E1 and the open / close switches 15 and 16 with a predetermined area. Surrounding through an insulating layer.

  The shield member Es1 is connected to the first power supply potential V1 via the eleventh open / close switch 63 and to the first fixed potential V3 via the twelfth open / close switch 64. As shown in FIG. 10, the output of the operational amplifier 61 is electrically connected to the inverting input terminal of the operational amplifier 61 and the shield member Es1, and the non-inverting input terminal of the operational amplifier 61 is connected to the power supply potential V1 via the switch 63. The non-inverting input terminal of the operational amplifier 61 may be connected to the fixed potential V3 through the switch 64.

Hereinafter, operations common to the capacitance detection devices of FIGS. 9 and 10 will be described.
The control unit 17 controls switching of the open / close switches 14 to 16 and also controls switching of the open / close switches 63 and 64.
The relationship between the heights of the power supply potentials V1, V3, and V4 may be V1>V3> V4 or V1 <V3 <V4.

The basic operation of the capacitance detection device 60 is the same as that of the first embodiment.
FIGS. 13A to 13G are timing charts for explaining the operation of the capacitance detection device 60 of FIGS. 9 and 10, and show the relationship between the heights of the power supply potentials V1, V3, and V4 as V1>. V3> V4.

  In the electrostatic capacitance detection device 60, as in the first embodiment, the control unit 17 controls the first switch operation to return the open / close switch 14 from the open state to the closed state for a predetermined period of time (FIG. 13 ( After performing a)), the second switch operation (FIG. 13B) for returning the open / close switch 15 from the open state to the closed state for a predetermined period and returning the open state to the open state again, and the open / close switch 16 from the open state to the closed state for a predetermined period. The third switch operation (FIG. 13C) is repeated. As shown in FIG. 13C, the open / close switch 16 may be closed from the open state for a predetermined period during the first switch operation.

  By the first switch operation, both electrodes of the reference capacitor 13 are short-circuited, the potential Vin− of the inverting input terminal (−) of the comparator 12 rises to the potential V3 (FIG. 13 (e)), and the output signal of the comparator 12 Vout transitions from a high level to a low level (FIG. 13 (f)).

  By the second switch operation, the reference capacitor 13 is charged by the electric charge charged in the sensor electrode E1, and the potential Vin− is lowered. Although the potential VE1 (FIG. 13D) of the sensor electrode E1 is lowered by the second switching operation, the potential VE1 of the sensor electrode E1 becomes the power supply potential V1 again by the third switch operation.

  By repeating the second switch operation and the third switch operation, the potential Vin− of the inverting input terminal of the comparator 12 decreases according to the number of repetitions. When the potential Vin− of the inverting input terminal of the comparator 12 becomes equal to or lower than the power supply potential V4, the output signal of the comparator 12 transits to a high level. The control unit 17 counts the number of times of the second switch operation repeatedly performed until the output signal Vout of the comparator 12 transitions, and outputs a calculation result using this as a function.

  As described above, the operational amplifier 11, the comparator 12, the reference capacitor 13, the open / close switches 14 to 16, and the sensor electrode E <b> 1 are provided, and the open / close switches 14 to 16 are opened and closed as in the first embodiment. Similar to the capacitance detection device 10 of the first embodiment, conversion to distance information when used as a distance sensor is simple.

  Here, the surface of the sensor electrode E1 other than the electrode surface facing the conductor E0 and the wiring connecting the sensor electrode E1 and the open / close switches 15 and 16 have a parasitic capacitance Cα1 (not shown). Charges are accumulated in the parasitic capacitance Cα1 when the open / close switch 16 is closed, and accumulated in the parasitic capacitance Cα1 when the charge accumulated in the capacitor having the sensor electrode E1 as one electrode is moved to the reference capacitor 13. The generated charge also moves to the reference capacitor 13. For this reason, unnecessary charges are accumulated in the reference capacitor 13, and the detection accuracy of the capacitance detection device 60 is lowered and is easily affected by an electrical disturbance.

Therefore, the control unit 17 controls the open / close switches 63 and 64 so that the open / close switch 63 is moved from the open state after the open / close switch 15 is changed from the closed state to the open state and before the open / close switch 16 is changed from the closed state to the open state. Before the opening / closing switch 15 changes from the open state to the closed state, the opening / closing switch 63 is changed from the closed state to the open state, and the opening / closing switch 64 is changed simultaneously from the open state to the closed state. And the control part 17 is controlling so that the opening-and-closing switches 63 and 64 may not be in a closed state simultaneously. As described above, the open / close switches 63 and 64 are controlled, and the potential Vs1 (FIG. 13G) of the shield member Es1 is changed from at least immediately before the open / close switch 15 changes from the open state to the closed state. The potential is the same as the potential V3 until immediately after the transition to the open state.

  The potential Vs1 (FIG. 13 (g)) of the shield member Es1 is set to the same potential as the potential V3 at least immediately before the opening / closing switch 15 changes from the open state to the closed state until immediately after the opening / closing switch 15 changes from the closed state to the open state. As a result, the sensor electrode E1 and the wiring between the sensor electrode E1 and the open / close switches 15 and 16 from immediately before the open / close switch 15 transitions from the open state to the close state until immediately after the open / close switch 15 transitions from the closed state to the open state, No charge is accumulated in the capacity between the shield member Es1. Therefore, there is no charge transfer from the capacitor to the reference capacitor 13, and a decrease in the detection accuracy of the capacitance due to the influence of the parasitic capacitor Cα1 can be suppressed.

  As described above, the electrostatic capacitance detection device 60 of the present embodiment suppresses the influence of the parasitic capacitance Cα1 parasitic on the sensor electrode E1 and the wiring between the sensor electrode E1 and the open / close switches 15 and 16, and further, It has the following advantages.

  As shown in FIG. 13G, the potential Vs1 of the shield member Es1 and the potential of the sensor electrode E1 from at least immediately before the opening / closing switch 15 transitions from the open state to the closed state until immediately after the opening / closing switch 15 transitions from the closed state to the open state. By setting VE1 to substantially the same potential, leakage current between the sensor electrode E1 and the shield member Es1 can be suppressed even when there is an insulation failure between the sensor electrode E1 and the shield member Es1. Therefore, a capacitance detection result with less error can be obtained.

  As shown in FIG. 11, the output terminal of the operational amplifier 61, the inverting input terminal of the operational amplifier 61, and the shield member Es1 are electrically connected, and the non-inverting input terminal of the operational amplifier 61 is connected to the sensor electrode E1, thereby opening and closing the switch. The same effect as that of the capacitance detection device 60 of FIGS. 9 and 10 can be obtained without using 63 and 64.

[Sixth Embodiment]
14 and 15 are configuration diagrams showing a capacitance detection device 70 according to the sixth embodiment of the present invention. Elements common to those in FIG. 10 are denoted by common reference numerals. .
The capacitance detection device 70 shown in FIG. 14 includes a first current detection circuit (current detection) between the shield member Es1 of the capacitance detection device 60 of the fifth embodiment of FIG. 10 and the output terminal of the operational amplifier 61. ) 71, and the other configuration is the same as that of the capacitance detection device 60 of FIG.

16A to 16G are timing charts for explaining the operation of the capacitance detection device 70, and correspond to FIGS. 13A to 13G.
The basic operation of the capacitance detection device 70 is the same as that of the capacitance detection device 60. As shown in FIGS. 16A to 16C, the first switch operation is performed, and then the second switch Repeat the operation and the third switch operation.

  Here, under the control of the control unit 17, the open / close switch 16 is changed from the open state to the closed state by the third switch operation, and then the open / close switch 63 is changed from the closed state to the open state to close the open / close switch 64. Until this time, a period T1 is provided. In the period T1, the potential VE1 of the sensor electrode E1 and the potential Vs1 of the shield member Es1 are not the same potential.

  Therefore, the capacitance detection device 70 uses the current detection circuit 71 to detect the current flowing from the operational amplifier 61 to the shield member Es1 in the period T1. By detecting the current flowing through the shield member Es1, an insulation failure between the sensor electrode E1 and the shield member Es1 can be detected.

As described above, the capacitance detection device 70 according to the present embodiment can quickly detect an insulation failure between the sensor electrode E1 and the shield member Es1, so that the countermeasure when an insulation failure occurs is quickly implemented. it can.
Note that the timing for detecting an insulation failure between the shield member Es1, the sensor electrode E1, and the wiring connected to the sensor electrode E1 does not have to be the period T1 in FIG. An insulation failure between the shield member Es1 and the sensor electrode E1 and the wiring connected to the sensor electrode E1 may be detected at the timing of a period T2 shown in FIG.

FIGS. 17A to 17G are explanatory diagrams of other timings for detecting an insulation failure.
In the period from when the output Vout of the comparator 22 changes from the low level to the high level and immediately after the open / close switch 14 changes from the closed state to the open state, the open / close switch 15 changes from the open state to the closed state. 15 is open, the open / close switch 16 is closed, and the open / close switch 64 is closed, and the shield member Es1 is provided via the current detection circuit 71 during at least a part of the first period. By measuring the flowing current and detecting the current flowing through the shield member Es1, an insulation failure between the sensor electrode E1 and the shield member Es1 can be detected.

  In the example shown in FIG. 17, before the opening / closing switch 14 is changed from the open state to the closed state by the first switch operation (FIG. 17A), the opening / closing switch 15 is moved as shown in FIG. In the open state, the open / close switch 16 is changed from the open state to the closed state, and the potential VE1 of the sensor electrode E1 and the potential of the wiring connected thereto are fixed to the power supply potential V1.

  Here, the open / close switch 64 is changed from the open state to the closed state during the closed state of the open / close switch 16, and the potential Vs1 of the shield member Es1 is connected to the power supply potential V3 (FIG. 17 (g)). In this state, the current flowing between the operational amplifier 61 and the shield member Es1 is measured by the current detection circuit 71 during the period T2.

  During the period T2, the potential VE1 of the sensor electrode E1 and the potential of the wiring connected thereto are V1, the potential Vs1 of the shield member Es1 is V3, and VE1 ≠ VS, the sensor electrode E1 and the wiring connected thereto If the insulation of the shield member Es1 is good, the current flowing in the current detection circuit 71 is not detected. However, if the insulation between the sensor electrode E1 and the wiring connected thereto and the shield member Es1 is broken, the current detection circuit 71 The flowing current is detected.

  In FIG. 17, the open / close switch 14 is changed from the open state to the closed state while the open / close switch 16 is in the closed state. You may make it change to a closed state. After the elapse of the period T2, before the start of the second switch operation, the open / close switch 64 is changed from the closed state to the open state, the open / close switch 63 is changed from the open state to the closed state, and the open / close switches 14 and 16 are closed. To the open state.

In the example of FIG. 15, the operational amplifier 61 in FIG. 14 is deleted. In FIG. 14, the wiring connected to one end of the open / close switch 63, one end of the open / close switch 64, and the non-inverting input terminal of the operational amplifier 61. By using wiring connected to one end of the switch 63, one end of the open / close switch 64, and the shield member Es1, and making the open / close control of each open / close switch equal to that in FIG. 14, the same effect as in the example of FIG. 14 can be obtained.
The above-described capacitance detection device 70 has a configuration in which the current detection circuit 71 is provided in the fifth capacitance detection device 60, and the same effect as that of the capacitance detection device 60 is obtained, and the sensor electrode E1 shield is provided. There is an advantage that a poor insulation with the member Es1 can be detected quickly.

[Seventh Embodiment]
18 and 19 are views showing the characteristics of the capacitance detection device 80 according to the seventh embodiment of the present invention.
FIG. 20 is a diagram showing a part A of FIGS.

  A capacitance detection capacitor 80 in FIG. 18 is a device in which a first external shield member Eso1 and an open / close switch 81 are provided in the capacitance detection device 70 in FIG. 14 of the sixth embodiment. The external shield member Eso1 surrounds at least a part of the shield electrode Es1 and the sensor electrode E1, the wiring connecting the sensor electrode E1 and the open / close switches 15 and 16, and is connected to the third fixed potential Vso1. The open / close switch 81 has one end connected to the fixed potential Vso1, the other end connected to the non-inverting input terminal of the operational amplifier 61, the other end connected to the first power supply potential V1, and the other end and one end connected to the first fixed potential V1. The other end of the open / close switch 64 connected to the potential V3 is connected.

The control unit 17 controls the opening / closing of the respective open / close switches 14, 15, 16, 63, 64, 81, so that the open / close switches 15, 16 are not simultaneously closed, and the open / close switches 63, 64, 81 Two or more are controlled so as not to be closed simultaneously.
The other configuration of the capacitance detection device 80 is the same as that of the capacitance detection device 70 of the sixth embodiment in FIG.

  In addition, if there is a portion that is not surrounded by the shield member Es1 in the surface that does not oppose the measured capacitance Cx11 of the sensor electrode E1 and the wiring that connects the sensor electrode E1 and the open / close switches 15 and 16 with the shield member Es1, It is predicted that a parasitic capacitance is generated between the shield member Eso1 and a conductor such as a nearby wiring, and the measurement error is increased. Therefore, it is desirable to surround the surface of the sensor electrode E1 that does not face the conductor E0 and the wiring that connects the sensor electrode E1 and the open / close switches 15 and 16 as much as possible with the shield member Es1. Further, since the potential Vs of the shield member Es1 fluctuates in conjunction with the potential VE1 of the sensor electrode E1, there is a high possibility of generating electromagnetic noise. The shield member Es1 is connected to the third fixed potential Vso1. It is desirable to surround the shield member Es1 with the member Eso1.

FIGS. 21A to 21G are timing charts showing an operation example of the capacitance detection device 80.
The basic operation of the capacitance detection device 80 is that the open / close switches 14, 15, 64, 81 are closed, the open / close switches 14, 16, 63 are closed, and then the open / close switches 14, 16, 63 are closed. A first switch operation is performed in which at least the open / close switches 16 and 63 are synchronously shifted to the open state, and then the open / close switches 15 and 64 are synchronized to be closed for a certain period and then returned to the open state. And a third switch operation in which the on / off switch 16 is closed for a certain period after the second switch operation, and at least the on / off switch 16 and the on / off switch 63 are synchronized to make a transition from the closed state to the open state. In the third switch operation, a period is provided in which the open / close switches 63 and 64 are opened and the open / close switch 81 is closed while the open / close switch 16 is closed.

  In the timing chart of FIG. 21, the open / close switch 16 is open and the open / close switch 63 is closed before the first switch operation, and the open / close switch 16 and the open / close switch 14 are synchronized and opened by the first switch operation. After the transition from the closed state to the closed state, the open / close switches 14, 16, and 63 are synchronized to transition from the closed state to the open state, and the open / close switches 15 and 64 are synchronized by the second switch operation and closed for a certain period of time. Returning to the open state, the third switch operation synchronizes the open / close switches 16 and 81 from the open state to the closed state. Thereafter, only the open / close switch 81 changes to the open state, and the open / close switch 63 changes from the open state to the closed state. And a transition synchronized with the open / close switches 16 and 63 from the closed state to the open state.

  Immediately before the second switch operation, the open / close switches 16, 63 are synchronously transitioned from the closed state to the open state, and the open / close switch 15 and the open / close switch 64 are synchronously opened / closed by the second switch operation. The potentials VE1 and Vs1 of the sensor electrode E1 and the shield member Es1 from immediately before the open / close switches 16, 63 are synchronized to transit from the closed state to the open state until the open / close switches 15, 64 are synchronized to transit from the closed state to the open state. Are substantially equal, there is no charge due to the parasitic capacitance Cα11 formed between the shield electrode Es1 and the sensor electrode E1 and the wiring connecting the sensor electrode E1 and the open / close switches 15 and 16, and the sensor electrode E1 and sensor electrode E1. If there is an insulation failure between the wiring connecting the open / close switches 15 and 16 and the shield member Es1, the sheet is connected via the insulation failure portion. The charge moving from the de member Es1 to the sensor electrodes E1 and the sensor electrodes E1 and closing switches 15 and 16 is not the detection accuracy of the sensor is increased. The potential Vs1 of the shield member Es1 is periodically changed by the second and third switch operations, and noise is generated. However, since the shield member Eso1 is fixed to the potential Vso1, noise may be radiated to the outside. Is prevented.

  Here, under the control of the control unit 17, the open / close switch 81 is closed after the open / close switch 16 is changed from the open state to the closed state by the third switch operation until the open / close switch 16 is opened. A period T1 is provided within a period during which the open / close switch 81 is closed.

  In the period T1, since the potential VE1 of the sensor electrode E1 and the potential Vs1 of the shield member Es1 do not become the same potential, the capacitance detection device 80 uses the current detection circuit 71, and the sensor electrode E1 and the shield member Es1 The current flowing therebetween can be detected in the period T1. When the insulation between the sensor electrode E1 and the shield member Es1 is good, there is no current flowing between the sensor electrode E1 and the shield member Es1, but when the insulation between the sensor electrode E1 and the shield member Es1 is poor, A current flows between the sensor electrode E1 and the shield member Es1. Therefore, the insulation failure between the sensor electrode E1 and the shield member Es1 can be detected by detecting the current flowing between the sensor electrode E1 and the shield member Es1.

  Further, since the potential Vs1 of the shield member E1 in the period T1 is the same potential Vso1 as that of the external shield member Eso1, even if the insulation between the shield member Es1 and the external shield member Eso1 is poor, the shield member. There is no current flowing from Es1 to the external shield member Eso1, and the insulation failure between the shield member Es1 and the sensor electrode E1, the wiring connecting the sensor electrode E1 and the open / close switches 15 and 16, and the shield member Es1 can be detected.

  Note that the timing for detecting an insulation failure between the shield member Es1 and the sensor electrode E1 and the wiring connecting the sensor electrode E1 and the open / close switches 15 and 16 need not be in the period T1 of FIG. An insulation failure between the shield member Es1 and the wiring connecting the sensor electrode E1 and the sensor electrode E1 and the open / close switches 15 and 16 may be detected at the timing of the period T2 shown in FIG.

22A to 22G are explanatory diagrams of other timings for detecting an insulation failure.
In the period from when the output Vout of the comparator 22 changes from the low level to the high level and immediately after the open / close switch 14 changes from the closed state to the open state, the open / close switch 15 changes from the open state to the closed state. 15 is open, the open / close switch 16 is closed, and the open / close switch 81 is closed. A period T2 is set during the open / close switch 15 is open, the open / close switch 16 is closed, and the open / close switch 81 is closed. The sensor electrode E1 and the shield member Es1 are provided by measuring the current flowing through the shield member Es1 via the current detection circuit 71 and detecting the current flowing through the shield member Es1 during at least a part of the period T2. It is possible to detect an insulation failure between the two.

  In FIG. 22, for example, before the opening / closing switch 14 is changed from the open state to the closed state by the first switch operation (FIG. 22 (a)), the opening / closing switch 63 is moved from the closed state as shown in FIG. 22 (c). The open / close switch 15 is opened, the open / close switch 16 and the open / close switch 81 are changed from the open state to the closed state, and the potential VE1 of the sensor electrode E1 and the potential of the wiring connected thereto are changed to the power supply potential V1. The potential Vs1 of the shield member Es1 is fixed to the potential Vso1, and a potential difference is provided between them.

  A period T2 is set during a period in which the open / close switches 15, 63, 64 are kept open and the open / close switches 16, 81 are kept closed, and flows to the shield member Es1 via the current detection circuit 71 at least during this period T2. Detect current. The open / close switch 14 is changed from the open state to the closed state, and after the period T2, the open / close switch 81 is changed from the open state to the closed state, and the open / close switch 63 is changed from the open state to the closed state. 16 and 63 are synchronized to return from the closed state to the open state. In other words, the first switch operation is terminated to prepare for the second switch operation.

  19, the operational amplifier 61 is omitted from the capacitance detection device 80 in FIG. 18. In FIG. 18, one end of the open / close switch 63, one end of the open / close switch 64, and one end of the open / close switch 81. In FIG. 19, the wiring connected to the non-inverting input terminal of the operational amplifier 61 is a wiring connected to one end of the open / close switch 63, one end of the open / close switch 64, one end of the open / close switch 81, and the shield member Es1. By making the opening / closing control equal to that in FIG. 18, the same effect as in the example of FIG. 18 can be obtained.

  As described above, the capacitance detection device 80 uses the current detection circuit 71 to detect the current flowing between the sensor electrode E1 and the shield member Es1 in the period T2. By detecting the current flowing between the sensor electrode E1 and the shield member Es1, an insulation failure between the sensor electrode E1 and the shield member Es1 can be detected.

[Eighth Embodiment]
23, 24, and 25 are circuit diagrams showing a capacitance detection device 90 according to the eighth embodiment of the present invention. Elements common to the elements in FIG. 4 showing the second embodiment are shown in FIG. Are denoted by a common reference numeral.
FIG. 26 is a diagram showing an outline of part A in FIGS.
23 includes a first and second operational amplifiers 21 and 31, a comparator 22, first and second reference capacitors 23 and 33, first to sixth open / close switches 24, 25, 26, 34, 35, 36, first and second sensor electrodes E1, E2, and a control unit 37, which are connected in the same manner as in FIG. 4 of the second embodiment.

  As shown in FIG. 26, the sensor electrodes E1 and E2 are formed with capacitors with measured capacitances Cx11 and Cx21 between the conductor E0 and the conductor E0, respectively. Becomes one electrode of each capacitor. The sensor electrodes E1 and E2 are arranged close to each other, and a capacitance Cx0 is also formed between the sensor electrodes E1 and E2.

Unlike the second embodiment, the capacitance detection device 90 is provided with a first shield member Es1 and a second shield member Es2.
The shield member Es1 surrounds a surface of the sensor electrode E1 other than the electrode surface facing the conductor E0 via a predetermined insulating layer, and also surrounds the wiring connecting the sensor electrode E1 and the open / close switches 25 and 26 with a predetermined area. Surrounding through an insulating layer.

  The shield member Es2 surrounds a surface of the sensor electrode E2 other than the electrode surface facing the conductor E0 with a predetermined insulating layer, and also surrounds the wiring connecting the sensor electrode E2 and the open / close switches 35 and 36 with a predetermined area. Surrounding through an insulating layer.

The output terminal of the operational amplifier 61 is connected to the shield member Es1.
The non-inverting input terminal (+) of the operational amplifier 61 has one end of the open / close switch 63 whose other end is connected to the first power supply potential V1 and one end of the open / close switch 64 whose other end is connected to the first fixed potential V3. The inverting input terminal (−) of the operational amplifier 61 is connected to the output terminal of the operational amplifier 61.

The output terminal of the operational amplifier 91 is connected to the shield member Es2.
The non-inverting input terminal (+) of the operational amplifier 91 has one end of the open / close switch 93 whose other end is connected to the second power supply potential V2 and one end of the open / close switch 94 whose other end is connected to the second fixed potential V5. The inverting input terminal (−) of the operational amplifier 91 is connected to the output terminal of the operational amplifier 91.

The control unit 37 controls the switching operations of the open / close switches 24 to 26 and 34 to 36 and also controls the switching operations of the open / close switches 63, 64, 93 and 94. In the combination of the open / close switches 25 and 26, the open / close switches 35 and 36, the open / close switches 63 and 64, and the open / close switches 93 and 94, the open / close switches in each combination are not simultaneously closed.
The relationship between the heights of the potentials V1, V2, V3, and V5 may be V1>V3>V5> V2, or may be V1 <V3 <V5 <V2.

The basic operation of the capacitance detection device 90 is the same as the basic operation of the capacitance detection device 20 of the second embodiment.
FIGS. 27A to 27I are timing charts for explaining the operation of the capacitance detection device 90 of FIG. 23. The relationship between the heights of the power supply potentials V1, V2, V3, and V5 is represented by V1> V3. >V5> V2.

  In the capacitance detection device 90, as in the second embodiment, the first switch operation (see FIG. 5) is performed by controlling the control unit 37 to return the open / close switches 24 and 34 from the open state to the closed state for a predetermined period. 27 (a)), the second switch operation (FIG. 27 (b)) for returning the open / close switches 25, 35 from the open state to the open state again for a predetermined period, and the open / close switches 26, 36 The third switch operation (FIG. 27 (c)) for closing from the open state for a predetermined period is repeated. As shown in FIG. 27, when the first switch is operated, the open / close switches 26 and 36 may be closed from the open state for a predetermined period.

  In the above switch operation, the open / close switches 63, 93 are changed from the open state to the closed state during the period in which the open / close switches 26, 36 are in the closed state, and after the transition of the open / close switches 26, 36 from the closed state to the open state. Before the switch operation, the open / close switches 63, 93 are changed from the closed state to the open state, and in the second switch operation, the open / close switches 25, 35, 64, 94 are simultaneously changed from the open state to the closed state. 35 is changed from the closed state to the open state, and the open / close switches 64, 94 are changed from the closed state to the open state after the open / close switches 26, 36 are changed from the open state to the closed state.

  By the first switch operation, both electrodes of the reference capacitors 23 and 33 are short-circuited, and the potential Vin− of the inverting input terminal (−) of the comparator 22 rises to the potential V3 (FIG. 27E). The potential Vin + of the non-inverting input terminal (+) drops to the potential V5 (FIG. 27 (e)). As a result, the output signal Vout of the comparator 22 transits from a high level to a low level (FIG. 27 (g)).

  By the second switch operation, the charge (Cx11 (V1-V3)) associated with the fluctuation of the potential VE1 of the sensor electrode E1 is charged in the reference capacitor 23, and the potential Vin- is decreased. At the same time, the reference capacitor 33 is charged with the charge (Cx21 (V2-V5)) associated with the fluctuation of the potential VE2 of the sensor electrode E2, and the potential Vin + rises.

The potential VE1 (FIG. 27 (d)) of the sensor electrode E1 is lowered by the second switching operation and becomes the same potential as the first fixed potential V3. However, the potential VE1 of the sensor electrode E1 is obtained by the third switch operation. Rises again to the power supply potential V1.
The potential VE2 (FIG. 27 (f)) of the sensor electrode E2 rises by the second switching operation and becomes the same potential as the second fixed potential V5, but the potential VE2 of the sensor electrode E2 by the third switch operation. Drops again to the power supply potential V2.

  By repeating the second switch operation and the third switch operation, the potential Vin− of the inverting input terminal (−) of the comparator 22 decreases according to the number of repetitions, and the non-inverting input terminal (+) of the comparator 22. The potential Vin + rises.

  When the potential Vin− of the inverting input terminal (−) of the comparator 22 becomes equal to or lower than the potential Vin + of the non-inverting input terminal (+) of the comparator 22, the output signal of the comparator 22 transitions to a high level. The control unit 37 counts the number of times of the second switch operation repeatedly performed until the output signal Vout of the comparator 22 transitions to a high level, and outputs a calculation result using this as a function.

  The change of the potential Vin− is proportional to the number of times of the second switch operation and substantially proportional to the measured capacitance Cx11, and the change of the potential Vin + is also proportional to the number of times of the second switch operation and substantially proportional to the measured capacitance Cx21. To do. Since the measured capacitances Cx11 and Cx21 are inversely proportional to the distance between the sensor electrodes E1 and E2 and the conductor E0, the output signal Vout of the comparator 22 is also a function of the distance. Therefore, when the capacitance detection device 90 is used as a distance sensor, conversion into distance information is easy.

  Further, the ratio SE1 / Cs2 of the area SE1 of the sensor electrode E1 and the capacity Cs2 of the first reference capacitor 23 and the ratio SE2 / Cs3 of the area SE2 of the sensor electrode E2 and the capacity Cs3 of the second reference capacitor 33 are made equal. Thus, the influence of electromagnetic disturbance can be suppressed, and the area SE1 of the sensor electrode E1, the potential variation width SE1 (V1-V3) of the sensor electrode E1, the area SE2 of the sensor electrode E2, and the potential variation width SE1 (V5-) of the sensor electrode E2. Generation of radio noise can also be suppressed by equalizing V2).

  Here, the surface of the sensor electrode E1 other than the electrode surface facing the conductor E0 and the wiring connecting the sensor electrode E1 and the open / close switches 25 and 26 have a parasitic capacitance Cα1 (not shown), and the potential of the conductor E0. Is constant, the charge of Cα1 (V1−V3) moves to the reference capacitor 23 every time the second switch operation and the third switch operation are repeated by the parasitic capacitance Cα1, and the potential of the conductor E0 is constant. Then, due to the parasitic capacitance Cx0 formed between the sensor electrode E1 and the sensor electrode E2, the charge of Cx0 (V1−V2−V3 + V5) is changed to the reference capacitance 23 every time the second switch operation and the third switch operation are repeated. Move to. Therefore, unnecessary charges are accumulated in the reference capacitor 23.

  Similarly, the surface of the sensor electrode E2 other than the electrode surface facing the conductor E0 and the wiring connecting the sensor electrode E2 and the open / close switches 35 and 36 have a parasitic capacitance Cα2 (not shown). With this parasitic capacitance Cα2, the charge of Cα2 (V2-V5) moves to the reference capacitor 23 each time the second switch operation and the third switch operation are repeated, and is formed between the sensor electrode E1 and the sensor electrode E2. Due to the parasitic capacitance Cx0, the charge of Cx0 (V2−V1−V5 + V3) moves to the reference capacitor 33 every time the second switch operation and the third switch operation are repeated. Thus, the presence of these parasitic capacitances Cα1, Cα2, and Cx0 reduces the detection accuracy of the capacitance detection device 90 and is easily affected by electrical disturbance.

  Therefore, in the capacitance detection device 90, the shield member Es1 surrounds a surface of the sensor electrode E1 other than the electrode surface facing the conductor E0 via a predetermined insulating layer, and the sensor electrode E1 and the open / close switches 25, 26 And the shield member Es2 surrounds the surface of the sensor electrode E2 other than the electrode surface facing the conductor E0 via the predetermined insulating layer, and the sensor. Since the periphery of the wiring connecting the electrode E2 and the open / close switches 35 and 36 is surrounded by a predetermined insulating layer, it is connected to the same sensor electrode and sensor electrode as compared with the capacitance detection device 20 according to the second embodiment. When the wiring configuration to be used is used, the area where the sensor electrodes E1 and E2 and the wiring connected thereto are directly opposed to each other is reduced, so that Cx0 is reduced.

  The shield member Es1 surrounds a surface of the sensor electrode E1 other than the electrode surface facing the conductor E0 via a predetermined insulating layer, and surrounds the wiring connecting the sensor electrode E1 and the open / close switches 25 and 26. Are surrounded by a predetermined insulating layer, and as shown in FIGS. 27D and 27H, the shield member Es2 has a predetermined insulating layer on the surface other than the electrode surface facing the conductor E0 of the sensor electrode E2. In addition, the parasitic capacitances Cα1 and Cα2 are formed in order to surround the wiring connecting the sensor electrode E2 and the open / close switches 35 and 36 with a predetermined insulating layer. As shown in (f), (h), (i), at least before the opening / closing switches 26, 36 are changed from the open state to the closed state until immediately after the opening / closing switches 25, 35 are changed from the closed state to the open state. First sensor electrode E The first potential VE1 and the potential Vs1 of the first shield member Es1 are equal, and the potential VE2 of the second sensor electrode E2 and the potential Vs2 of the first shield member Es2 are equal.

  At least the potential VE1 of the first sensor electrode E1 and the potential of the first shield member Es1 from before the transition of the open / close switch 26 to the open state until immediately after the transition of the open / close switch 25 from the closed state to the open state. By making Vs1 equal, the sensor electrode E1 and the sensor electrode E1 in the state where there is no charge accumulation in the capacitance between the sensor electrode E1 and the wiring between the sensor electrode E1 and the open / close switches 25 and 26 and the shield member Es1. The amount of change before and after the transition from the open state to the closed state of the open / close switch 25 in the capacitance (CX11, Cα1, Cx0) in which the wiring between E1 and the open / close switches 25 and 26 serves as one electrode is accumulated in the reference capacitor 23. .

  Here, as described above, Cx0 is smaller than that of the capacitance detection device 20 according to the second embodiment, and the shield member Es1 has a predetermined surface other than the electrode surface facing the conductor E0 of the sensor electrode E1. The main component of Cα1 is composed of the sensor electrode E1 and the sensor electrode E1 in order to surround the wiring connecting the sensor electrode E1 and the open / close switches 25 and 26 with a predetermined insulating layer. Since the capacitance is between the wiring between the open / close switches 25 and 26 and the shield member Es1, the movement of charges to the reference capacitance 23 due to Cα1 and Cx0 is reduced, and the electrostatic capacitance due to the influence of parasitic capacitance It is possible to suppress a decrease in detection accuracy.

  Similarly, the potential VE2 of the second sensor electrode E2 and the second shield member are at least before the opening / closing switch 36 transitions from the closed state to the open state until immediately after the opening / closing switch 35 transitions from the closed state to the open state. By equalizing the potential Vs2 of Es2, the sensor electrode E2 in the state where there is no charge accumulation in the capacitance between the sensor electrode E2, the wiring between the sensor electrode E2 and the open / close switches 35 and 36, and the capacitance between the shield member Es2. The change amount before and after the transition from the open state of the open / close switch 35 to the closed state in the capacitor (CX21, Cα2, Cx0) in which the wiring between the sensor electrode E2 and the open / close switches 35, 36 serves as one electrode becomes the reference capacitor 33. Accumulated.

  Here, as described above, Cx0 is smaller than that of the capacitance detection device 20 according to the second embodiment, and the shield member Es2 has a predetermined surface other than the electrode surface facing the conductor E0 of the sensor electrode E2. In addition to surrounding through the insulating layer and surrounding the wiring connecting the sensor electrode E2 and the open / close switches 35 and 36 with a predetermined insulating layer, the main component of Cα2 is the sensor electrode E2 and the sensor electrode E2. Since the capacitance is between the wiring between the open / close switches 25 and 26 and the shield member Es2, the movement of charges to the reference capacitance 33 due to Cα2 and Cx0 is reduced, and the capacitance due to the influence of parasitic capacitance is reduced. A decrease in detection accuracy can be suppressed.

  As described above, the capacitance detection device 90 of FIG. 23 according to the present embodiment suppresses the influence of parasitic capacitance that is parasitic on the wiring between the sensor electrode E1 and the sensor electrode E2 and the wiring connected thereto. Has the following advantages.

  As shown in FIG. 27H, the potential VE1 of the first sensor electrode E1 and the first potential are at least before the opening / closing switch 26 is changed from the open state to the closed state until immediately after the opening / closing switch 25 is changed from the closed state to the open state. By making the potential Vs1 of one shield member Es1 equal, even if there is an insulation failure between the sensor electrode E1 and the shield member Es1, the charge caused by the current flowing between the sensor electrode E1 and the shield member Es1 Is not stored in the reference capacitor 23.

  In addition, as shown in FIG. 27 (i), the potential VE2 of the second sensor electrode E2 is at least before the opening / closing switch 36 is changed from the open state to the closed state until immediately after the opening / closing switch 35 is changed from the closed state to the open state. And the potential Vs2 of the second shield member Es2 are equalized, even if there is an insulation failure between the sensor electrode E2 and the shield member Es2, this is caused by the current flowing between the sensor electrode E2 and the shield member Es2. The charge to be stored is not accumulated in the reference capacitor 33. Therefore, it is possible to improve the accuracy when measuring the capacitance formed between the sensor electrodes that are measurement targets.

  24, the operational amplifiers 61 and 91 are omitted from the electrostatic capacitance detection apparatus 90 of FIG. 23. In FIG. 23, one end of the open / close switch 63, one end of the open / close switch 64, and the operational amplifier 61 are omitted. In FIG. 24, the wiring connected to the non-inverting input terminal is a wiring connected to one end of the open / close switch 63, one end of the open / close switch 64, and the shield member Es1, and in FIG. 23, one end of the open / close switch 93 and one end of the open / close switch 94. In FIG. 24, the wiring connected to the non-inverting input terminal of the operational amplifier 91 is the wiring connected to one end of the open / close switch 93, one end of the open / close switch 94, and the shield member Es2, and the open / close control of each open / close switch is as shown in FIG. By making them equal, the same effect as the example of FIG. 23 can be obtained.

  25, the open / close switches 63, 64, 93, and 94 are omitted from the capacitance detection device 90 of FIG. 23, and the wiring connected to the sensor electrode E1 is non-inverted by the operational amplifier 61. The wiring connected to the input terminal and the wiring connected to the sensor electrode E2 is connected to the non-inverting input terminal of the operational amplifier 91. For the control of the open / close switch in the example of FIG. By eliminating this control, the capacitance detection device 90 of FIG. 25 can obtain the same effect as the capacitance detection device 90 of FIG.

[Ninth Embodiment]
28 and 29 are configuration diagrams showing the capacitance detection device 100 according to the ninth embodiment of the present invention. Elements common to those in FIGS. 23, 24 and 25 are denoted by common reference numerals. It is attached.

  The capacitance detection device 100 of FIG. 28 includes a first current detection circuit 71 between the shield member Es1 of the capacitance detection device 90 of FIG. 23 of the eighth embodiment and the output terminal of the operational amplifier 61. The second current detection circuit 101 is provided between the shield member Es2 and the output terminal of the operational amplifier 91, and the other configuration is the same as that of the capacitance detection device 90 of FIG.

FIGS. 30A to 30I are timing charts for explaining the operation of the capacitance detection apparatus 100, and correspond to FIGS. 27A to 27I.
The basic operation of the capacitance detection device 100 of FIG. 28 is the same as that of the capacitance detection device 90 of FIG. 23, and the first switch operation is performed as shown in FIGS. Thereafter, the second switch operation and the third switch operation are repeated.
As with the capacitance detecting device 90, in the combination of the open / close switches 25 and 26, the open / close switches 35 and 36, the open / close switches 63 and 64, and the open / close switches 93 and 94, the combination open / close switches are simultaneously closed. There is nothing.

  Here, before the open / close switches 26 and 36 are changed from the closed state to the open state by the control of the control unit 37, the open / close switches 63 and 93 are changed from the open state to the closed state, and the open / close switches 26 and 36 are closed. After the transition from the open state to the open state, the open / close switches 63, 93 are changed from the closed state to the open state, and in the second switch operation, the open / close switches 25, 35, 64, 94 are simultaneously changed from the open state to the closed state. After the transition of the switches 25, 35 from the closed state to the open state, the open / close switches 64, 94 are shifted from the closed state to the open state, the open / close switches 26, 36 are closed, the open / close switches 25, 35 are open, A period T1 is provided in which 64 and 94 are closed and the open / close switch filters 63 and 93 are open.

  Therefore, the electrostatic capacitance detection device 100 uses the current detection circuit 71 to detect the current flowing through the shield member Es1 via the open / close switch 63 during the period T1, and uses the current detection circuit 101 to detect the shield member via the open / close switch 93. The current flowing through Es2 is detected in period T1. By detecting the current flowing through the shield member Es1 via the open / close switch 63, it is possible to detect an insulation failure between the sensor electrode E1 and the shield member Es1. By detecting the current flowing through the shield member Es2 via the open / close switch 93, it is possible to detect an insulation failure between the sensor electrode E2 and the shield member Es2.

In the period T1, the potential VE1 of the sensor electrode E1 and the potential of the wiring connected to the sensor electrode E1 are V1, the potential Vs1 of the shield member Es1 is V3, and VE1 ≠ Vs1, and the sensor electrode E1, the wiring connected thereto, and the shield member Es1. If the insulation is good, the current flowing in the current detection circuit 71 is not detected. However, if the insulation between the sensor electrode E1 and the wiring connected thereto and the shield member Es1 is broken, the current flowing in the current detection circuit 71 is detected. Is done. On the other hand, the potential VE2 of the sensor electrode E2 and the potential of the wiring connected thereto are V2, the potential Vs2 of the shield member Es2 is V5, and VE2 ≠ Vs2, and the sensor electrode E2 and the wiring connected thereto and the shield member Es2 If the insulation is good, the current flowing in the current detection circuit 101 is not detected. However, if the insulation between the sensor electrode E2 and the wiring connected thereto and the shield member Es2 is broken, the current flowing in the current detection circuit 101 is detected. The
Therefore, the current detection circuit 71 can detect an insulation failure between the sensor electrode E1 and the wiring connected thereto and the shield member Es1. The current detection circuit 101 can detect an insulation failure between the sensor electrode E2 and the wiring connected thereto and the shield member Es2.

As described above, the capacitance detection device 100 can quickly detect an insulation failure between the sensor electrodes E1 and E2 and the shield members Es1 and Es2. it can.
Note that the timing of detecting an insulation failure between the shield members Es1 and E2, the sensor electrodes E1 and E2, and the wiring connected thereto does not have to be during the period T1 in FIG. An insulation failure between the shield members Es1, Es2 and the sensor electrode E1 and the wiring connected thereto may be detected at the timing of the period T2 shown in FIG.

  FIGS. 31A to 31I are explanatory diagrams of other timings for detecting an insulation failure, corresponding to FIGS. 30A to 30I, respectively, and the second and third switch operations are as follows. This is the same as the second and third switch operations using the timing of FIG.

  During a period from when the output Vout of the comparator 22 transits from a low level to a high level and immediately after the on / off switches 24 and 34 transit from the closed state to the open state, the on / off switches 25 and 35 transit from the open state to the closed state. A first period is provided in which the open / close switches 25, 35, 63, 93 are open and the open / close switches 26, 36, 64, 94 are closed, and the current detection circuit 71 is provided during at least a part of the first period. By measuring the current flowing through the shield member Es1 through the current and the current flowing through the shield member Es2 through the current detection circuit 101, and detecting the current flowing through the shield member Es1, the gap between the sensor electrode E1 and the shield member Es1 is detected. An insulation failure can be detected, and by detecting the current flowing through the shield member Es2, the sensor electrode E2 and the shield member Es2 It is possible to detect insulation failure between.

  In the example shown in FIG. 31, before the open / close switches 24, 34 are changed from the open state to the closed state by the first switch operation (FIG. 31 (a)), as shown in FIG. 31 (c). The open / close switches 26 and 36 are changed from the open state to the closed state when the pins 25 and 35 are open, the potential VE1 of the sensor electrode E1 and the potential of the wiring connected thereto are fixed to the power supply potential V1, and the potential VE2 of the sensor electrode E2 In addition, the potential of the wiring connected thereto is fixed to the power supply potential V2.

  Here, the open / close switches 63, 93 are opened during the closed state of the open / close switches 26, 36, the open / close switches 64, 94 are changed from the open state to the closed state, and the potential Vs1 of the shield member Es1 is set to the fixed potential V3. And the potential Vs2 of the shield member Es2 is connected to the fixed potential V5 (FIG. 31 (g)). In this state, during the period T2, the current flowing between the operational amplifier 61 and the shield member Es1 is measured by the current detection circuit 71, and the current flowing between the operational amplifier 91 and the shield member Es2 is measured by the current detection circuit 101. During the period T2, the potential VE1 of the sensor electrode E1 and the potential of the wiring connected thereto are V1, the potential Vs1 of the shield member Es1 is V3, and VE1 ≠ Vs1, and the sensor electrode E1 and the wiring connected thereto and the shield are shielded. If the insulation of the member Es1 is good, the current flowing in the current detection circuit 71 is not detected. However, if the insulation between the sensor electrode E1 and the wiring connected thereto and the shield member Es1 is broken, the current flowing in the current detection circuit 71 Is detected.

  In addition, during the period T2, the potential VE2 of the sensor electrode E2 and the potential of the wiring connected to the sensor electrode E2 are V2, the potential Vs2 of the shield member Es2 is V5, and VE2 ≠ Vs2, and the sensor electrode E2 and the wiring connected thereto. If the insulation between the shield member Es2 and the shield member Es2 is good, the current flowing in the current detection circuit 101 is not detected. However, if the insulation between the sensor electrode E2 and the wiring connected thereto and the shield member Es2 is broken, the current detection circuit 101 The flowing current is detected.

  In FIG. 31, the open / close switches 24, 34 are changed from the open state to the closed state while the open / close switches 26, 36 are closed, but the open / close switches 26, 36, 64, 94 are open / closed regardless of whether they are open / closed. The switches 24 and 34 may be transitioned from the open state to the closed state. After the period T2 elapses and before the start of the second switch operation, the open / close switches 64, 94 are changed from the closed state to the open state, the open / close switches 63, 93 are changed from the open state to the closed state, and then the open / close switch 24 is opened. , 34, 26, and 36 are changed from the closed state to the open state to finish the first switch operation, and the open / close switches 63 and 93 are changed from the closed state to the open state to prepare for the second switch operation.

  29, the operational amplifiers 61 and 91 are omitted from the electrostatic capacitance detection apparatus 100 of FIG. 28. In FIG. 28, one end of the open / close switch 63, one end of the open / close switch 64, and the operational amplifier 61 are omitted. In FIG. 29, the wiring connected to the non-inverting input terminal is a wiring connected to one end of the open / close switch 63, one end of the open / close switch 64, and the shield member Es1, and one end of the open / close switch 93 and one end of the open / close switch 94. In FIG. 29, the wiring connected to the non-inverting input terminal of the operational amplifier 91 is the wiring connected to one end of the open / close switch 93, one end of the open / close switch 94, and the shield member Es2, and the open / close control of each open / close switch is equal to FIG. By doing so, the same effect as the example of FIG. 28 is acquired.

  As described above, in the capacitance detection device 100 of FIG. 29, the current flowing through the shield member Es1 is detected via the current detection circuit 71, and the current flowing through the shield member Es2 is detected via the current detection circuit 101. Thereby, the insulation defect between each sensor electrode E1, E2 and shield member Es1, Es2 is detectable.

[Tenth embodiment]
32 and 33 are configuration diagrams showing a capacitance detection device 110 according to the tenth embodiment of the present invention.
FIG. 34 is a diagram showing a part A of FIGS. 32 and 33.

The capacitance detection capacitor 110 of FIG. 32 is similar to the capacitance detection device 100 of FIG. 28 of the ninth embodiment except that the first outer shield member Eso1, the second outer shield member Eso2, the open / close switch 81, , An open / close switch 111.
The external shield member Eso1 surrounds at least a part of the first sensor electrode E1, the wiring connecting the sensor electrode E1 and the open / close switches 25 and 26, and the first shield member Es1, and the third fixed potential Vso1. It is connected to the.

  The open / close switch 81 has one end fixed to the third fixed potential Vso1 and the other end connected to the first power supply potential V1 at the other end and one end of the open / close switch 64 whose one end is connected to the first fixed potential V3. The other end of the open / close switch 63 and the non-inverting input terminal of the operational amplifier 61 are connected, and ON / OFF is controlled by the control unit 37.

  The external shield member Eso2 surrounds at least a part of the second sensor electrode E2, the wiring connecting the sensor electrode E2 and the open / close switches 35 and 36, and the shield member Es2, and is connected to the fourth fixed potential Vso2. ing. The open / close switch 111 has one end connected to the fourth fixed potential Vso2 and the other end connected to the second power supply potential V2 at the other end and one end of the open / close switch 94 connected to the second fixed potential V5. The other end of the open / close switch 93 and the non-inverting input terminal of the operational amplifier 91 are connected to each other, and ON / OFF is controlled by the control unit 37.

  Other configurations of the capacitance detection device 110 other than the external shield members Eso1 and Eso2 and the open / close switches 81 and 111 are the same as those of the capacitance detection device 100 of the ninth embodiment.

In the combination of the open / close switches 25 and 26, the open / close switches 35 and 36, the open / close switches 63 and 64 and 81, and the open / close switches 93, 94 and 111, the open / close switches in each combination are not simultaneously closed.
It should be noted that if there is a portion of the shield member Es1 that does not oppose the conductor E0 of the sensor electrode E1 and the wiring that connects the sensor electrode E1 and the open / close switches 25 and 26, there is a portion that is not surrounded by the shield member Es1. A parasitic capacitance is generated between the member Eso1. Therefore, the shield member Es1 surrounds the surface of the sensor electrode E1 that does not face the conductor E0 and the wiring connecting the sensor electrode E1 and the open / close switches 25 and 26 as much as possible, and the external shield member Eso1 surrounds the shield member Es1. It is desirable to do.

  For the same reason, the shield member Es2 surrounds the surface of the sensor electrode E2 that does not face the conductor E0 and the wiring connecting the sensor electrode E2 and the open / close switches 35 and 36 as much as possible, and the external shield member Eso2 shields the shield member. It is desirable to surround Es2.

FIGS. 35A to 35I are timing charts showing an operation example of the capacitance detection device 110. FIG.
The basic operation of the capacitance detection device 110 is the same as that of the capacitance detection device 100, as shown in FIGS. 35 (a) to 35 (c). Repeat step 3 for switch operation.

  That is, in the same manner as in the second embodiment, the first switch operation for returning the open / close switches 24 and 34 from the open state to the closed state for a predetermined period of time by the control of the control unit 37 (FIG. 35 (a)). , The second switch operation (FIG. 35 (b)) for returning the open / close switches 25, 35 from the open state to the open state again for a predetermined period, and the open / close switches 26, 36 from the open state for a predetermined period. The third switch operation (FIG. 35 (c)) for closing is repeated.

  Note that the open / close switches 26 and 36 may be closed from the open state for a predetermined period before the open / close switches 25 and 35 are changed from the open state to the closed state by the second switch operation after the first switch operation.

  In the second switch operation, the open / close switches 25, 35, 64, 94 are simultaneously changed from the open state to the closed state, and the open / close switches 64, 94 are closed after the open / close switches 25, 35 are changed from the closed state to the open state. In the third switch operation, the open / close switches 63, 64, 93, 94 are opened and the open / close switches 81, 111 are closed during the third switch operation. A period T1 is provided, and the open / close switches 64, 94, 81, 111 are opened and the open / close switches 63, 93 are closed before the open / close switches 26, 36 transition from the closed state to the open state. After the transition from the closed state to the open state and before the transition of the open / close switches 25 and 35 from the open state to the closed state, the open / close switches 63 and 93 are changed from the closed state to the open state. That.

  In FIG. 35, when the open / close switches 25, 35 are returned from the closed state to the open state by the second switch operation, the potential Vs1 of the shield member Es1 is set to the fixed potential V3, and the potential Vs2 of the shield member Es2 is set to the fixed potential V5. Set to

  When the open / close switches 26 and 36 are returned from the open state to the closed state by the third switch operation, the potential Vs1 of the shield member Es1 is set to the power supply potential V1, and the potential Vs2 of the shield member Es2 is set to the power supply potential V2. Therefore, when the second switch operation and the third switch operation are repeated, the potentials Vs1 and Vs2 of the shield members Es1 and Es2 periodically change to generate noise, but the external shield members Eso1 and Eso2 are at the potential Vso1. , Vso2 is fixed to prevent external noise from being emitted. The potentials Vso1 and Vso2 may be the same potential.

  Here, under the control of the control unit 37, the third switch operation causes the open / close switches 26, 36 to transition from the closed state to the open state until the open / close switches 63, 93 transition from the open state to the closed state. A period T1 is provided, and the open / close switches 81 and 111 are closed during the period T1. In the period T1, the potential VE1 of the sensor electrode E1 is set to the power supply potential V1, the potential Vs1 of the shield member Es1 is set to the third fixed potential Vso1, the potential VE2 of the sensor electrode E2 is set to the power supply potential V2, and the shield The potential Vs2 of the member Es2 is set to the fourth fixed potential Vso2.

  In the period T1, the potential VE1 of the sensor electrode E1 and the potential of the wiring connected thereto are V1, the potential Vs1 of the shield member Es1 is Vso1, and VE1 ≠ Vs1, and the sensor electrode E1, the wiring connected thereto, and the shield member Es1. If the insulation is good, the current flowing in the current detection circuit 71 is not detected. However, if the insulation between the sensor electrode E1 and the wiring connected thereto and the shield member Es1 is broken, the current flowing in the current detection circuit 71 is detected. Is done.

  On the other hand, the potential VE2 of the sensor electrode E2 and the potential of the wiring connected thereto are V2, the potential Vs2 of the shield member Es2 is Vso2, and VE2 ≠ Vs2, and the sensor electrode E2 and the wiring connected thereto and the shield member Es2 If the insulation is good, the current flowing in the current detection circuit 101 is not detected. However, if the insulation between the sensor electrode E2 and the wiring connected thereto and the shield member Es2 is broken, the current flowing in the current detection circuit 101 is detected. The

  Therefore, an insulation failure between the sensor electrode E1 and the wiring connected thereto and the shield member Es1 can be detected by the current flowing through the current detection circuit 71. The insulation failure between the sensor electrode E2 and the wiring connected thereto and the shield member Es2 can be detected by the current flowing through the current detection circuit 101. In addition, since the potentials of the shield member Es1 and the first external shield member Eso1 are substantially equal in the period T1, even if there is an insulation failure between the shield member Es1 and the external shield member Eso1, the shield member Es1 and the external shield in the period T1. The current flowing between the member Eso1 is almost zero.

  Similarly, since the potentials of the shield member Es2 and the second external shield member Eso2 are substantially equal in the period T1, even if there is a poor insulation between the shield member Es2 and the external shield member Eso2, the shield member Es2 and the external part in the period T1. The current flowing between the shield member Eso2 is almost zero. Therefore, the current flowing in the current detection circuits 71 and 111 in the period T1 is suppressed from being affected by the insulation failure between the shield member Es1 and the first outer shield member Eso1 and between the shield member Es2 and the second outer shield member Eso2. It is possible to detect only an insulation failure that causes a decrease in accuracy of sensor operation.

  Note that the timing for detecting an insulation failure between the shield members Es1 and Es2, the sensor electrodes E1 and E2, and the wiring connected thereto does not have to be during the period T1 in FIG. An insulation failure between the shield members Es1, Es2 and the sensor electrodes E1, E2 and the wiring connected thereto may be detected at the timing of the period T2 shown in FIG.

  36 (a) to (i) are explanatory diagrams of other timings for detecting an insulation failure, and correspond to FIGS. 35 (a) to (i), respectively, and the second and third switch operations are as follows. This is the same as the second and third switch operations using the timing of FIG.

  During a period from when the output Vout of the comparator 22 transits from a low level to a high level and immediately after the on / off switches 24 and 34 transit from the closed state to the open state, the on / off switches 25 and 35 transit from the open state to the closed state. , A first period in which the open / close switches 25, 35, 63, 93, 64, 94 are open and the open / close switches 26, 36, 81, 111 are closed is provided in at least a part of the first period. By measuring the current flowing through the shield member Es1 through the current detection circuit 71 and the current flowing through the shield member Es2 through the current detection circuit 101 and detecting the current flowing through the shield member Es1, the sensor electrode E1 and the shield member Es1 are detected. Insulation failure between the sensor electrode E2 and the sheet can be detected by detecting the current flowing through the shield member Es2. It is possible to detect insulation failure between the de member Es2.

  In the example shown in FIG. 35, before the open / close switches 24, 34 are changed from the open state to the closed state by the first switch operation (FIG. 35 (a)), as shown in FIG. 35 (c). The open / close switches 26 and 36 are changed from the open state to the closed state when the pins 25 and 35 are open, the potential VE1 of the sensor electrode E1 and the potential of the wiring connected thereto are fixed to the power supply potential V1, and the potential VE2 of the sensor electrode E2 In addition, the potential of the wiring connected thereto is fixed to the power supply potential V2.

  Here, the open / close switches 63, 64, 93, 94 are opened during the closed state of the open / close switches 26, 36, the open / close switches 81, 111 are changed from the open state to the closed state, and the potential Vs1 of the shield member Es1. Is connected to the fixed potential Vso1, and the potential Vs2 of the shield member Es2 is connected to the fixed potential Vso2 (FIG. 35 (g)). In this state, during the period T2, the current flowing between the operational amplifier 61 and the shield member Es1 is measured by the current detection circuit 71, and the current flowing between the operational amplifier 91 and the shield member Es2 is measured by the current detection circuit 101.

  During the period T2, the potential VE1 of the sensor electrode E1 and the potential of the wiring connected thereto are V1, the potential Vs1 of the shield member Es1 is V3, and VE1 ≠ Vs1, and the sensor electrode E1 and the wiring connected thereto and the shield are shielded. If the insulation of the member Es1 is good, the current flowing in the current detection circuit 71 is not detected. However, if the insulation between the sensor electrode E1 and the wiring connected thereto and the shield member Es1 is broken, the current flowing in the current detection circuit 71 Is detected.

  In addition, during the period T2, the potential VE2 of the sensor electrode E2 and the potential of the wiring connected to the sensor electrode E2 are V2, the potential Vs2 of the shield member Es2 is V5, and VE2 ≠ Vs2, and the sensor electrode E2 and the wiring connected thereto. If the insulation between the shield member Es2 and the shield member Es2 is good, the current flowing in the current detection circuit 101 is not detected. However, if the insulation between the sensor electrode E2 and the wiring connected thereto and the shield member Es2 is broken, the current detection circuit 101 The flowing current is detected.

  Since the potentials of the shield member Es1 and the first external shield member Eso1 are substantially equal in the period T2, even if there is a poor insulation between the shield member Es1 and the external shield member Eso1, the shield member Es1 and the external shield member Eso1 in the period T2. The current flowing between and is almost zero.

  Similarly, since the potentials of the shield member Es2 and the second external shield member Eso2 are substantially equal in the period T2, even if there is a poor insulation between the shield member Es2 and the external shield member Eso2, the shield member Es2 and the external part in the period T2 The current flowing between the shield member Eso2 is almost zero. Therefore, the current flowing through the current detection circuits 71 and 101 in the period T2 is restrained from being affected by poor insulation between the shield member Es1 and the first outer shield member Eso1 and between the shield member Es2 and the second outer shield member Eso2. It is possible to detect only an insulation failure that causes a decrease in accuracy of sensor operation.

In FIG. 36, the open / close switches 24, 34 are changed from the open state to the closed state while the open / close switches 26, 36 are in the closed state, but the open / close switches 26, 36, 81, 111 are open / closed regardless of whether they are open or closed. The switches 24 and 34 may be transitioned from the open state to the closed state.
After the elapse of the period T2, before the start of the second switch operation, the open / close switches 81, 111 are changed from the closed state to the open state, the open / close switches 63, 93 are changed from the open state to the closed state, and then the open / close switch 24 is opened. , 34, 26, and 36 are changed from the closed state to the open state to finish the first switch operation, and the open / close switches 63 and 93 are changed from the closed state to the open state to prepare for the second switch operation.

  33 omits the switches 61 and 91 from the capacitance detection device 100 of FIG. 32. In FIG. 32, one end of the open / close switch 63, one end of the open / close switch 64, and the open / close switch 81 are omitted. In FIG. 33, the wiring connected to one end of the operational amplifier 61 and the non-inverting input terminal of the operational amplifier 61 is a wiring connected to one end of the open / close switch 63, one end of the open / close switch 64, one end of the open / close switch 81, and the shield member Es1. By making the switch open / close control the same as in FIG. 32, the same effect as in the example of FIG.

[Eleventh embodiment]
Various forms are conceivable for the sensor electrodes E1, E2 of the capacitance detection devices of the second embodiment, the fourth embodiment, and the eighth to tenth embodiments. In this embodiment, an embodiment of a sensor electrode will be described.

FIG. 37 is a diagram illustrating an example of the sensor electrodes E1 and E2.
The sensor electrode E1 and the sensor electrode E2 are opposed to each other and have convex portions that protrude to the other side. It arrange | positions so that the convex part of sensor electrode E1 and the convex part of sensor electrode E2 may not overlap. Further, the area of the sensor electrode E1 is equal to the area of the sensor electrode E2. The center of gravity of the sensor electrode E1 and the center of gravity of the sensor electrode E2 are substantially the same. In addition, the fluctuation ranges of the potentials of the sensor electrode E1 and the sensor electrode E2 are equal and opposite in phase.

  By equalizing the areas, the fluctuation ranges of the charges accumulated in the sensor electrode E1 and the sensor electrode E2 become equal. By matching the center of gravity, it is considered that the electric charges accumulated in the sensor electrode E1 and the sensor electrode E2 are concentrated near the center of gravity, so that the change in the electric moment when viewed from the outside is reduced and the generation of radio noise is suppressed. Is done. Further, the electric charges induced by the disturbance are also equal in the sensor electrode E1 and the sensor electrode E2, and if the circuit connected to the sensor electrodes E1, E2 is equivalent to the input before the comparator 22, the influence of the disturbance is reduced. Can do.

FIG. 38 is a diagram illustrating an example of the sensor electrodes E1 and E2.
The sensor electrode E1 and the sensor electrode E2 are arranged concentrically. The sensor electrode E1 surrounds the outside of the sensor electrode E2. The weight of the sensor electrode E1 and the center of gravity of the sensor electrode E2 are substantially the same. Further, the area of the sensor electrode E1 is equal to the area of the sensor electrode E2. The sensor electrodes E1 and E2 have a symmetrical shape with two or more planes of symmetry passing through the center of gravity.

  As described above, by forming the sensor electrodes E1 and E2 symmetrically on two or more symmetry planes passing through the center of gravity, the change in electric moment when viewed from the outside is reduced, and radio noise can be further suppressed. Further, the charges induced by the disturbance can be made more uniform by the sensor electrode E1 and the sensor electrode E2, and if the circuit connected by the sensor electrodes E1 and E2 is equivalent immediately before the input to the comparator 22, the disturbance Can be further reduced.

FIG. 39 is a diagram illustrating an example of the sensor electrodes E1 and E2.
The sensor electrode E2 is square, and the sensor electrode E1 is formed so as to surround the sensor electrode E2.
The center of gravity of the sensor electrode E1 and the center of gravity of the sensor electrode E2 are substantially the same. Further, the area of the sensor electrode E1 is equal to the area of the sensor electrode E2. The sensor electrodes E1 and E2 have a symmetrical shape with two or more planes of symmetry passing through the center of gravity.

FIG. 40 is a diagram illustrating an example of the sensor electrodes E1 and E2.
The sensor electrode E2 is rectangular, and the sensor electrode E1 is formed so as to surround the sensor electrode E2.
The center of gravity of the sensor electrode E1 and the center of gravity of the sensor electrode E2 are substantially the same. Further, the area of the sensor electrode E1 is equal to the area of the sensor electrode E2. The sensor electrodes E1 and E2 have a symmetrical shape with two or more planes of symmetry passing through the center of gravity.

FIG. 41 is a diagram illustrating an example of the sensor electrodes E1 and E2.
Each of the sensor electrode E1 and the sensor electrode E2 can be composed of an arbitrary number of conductors. In FIG. 11, the sensor electrode E1 is composed of two square conductors, the sensor electrode E2 is composed of two square conductors, and the conductor of the sensor electrode E1 and the conductor of the sensor electrode E2 are arranged diagonally. Yes.

  The center of gravity of the sensor electrode E1 and the center of gravity of the sensor electrode E2 are substantially the same. Further, the area of the sensor electrode E1 is equal to the area of the sensor electrode E2. The sensor electrodes E1 and E2 are symmetric with respect to two or more symmetry planes passing through the center of gravity.

FIG. 42 is a diagram illustrating an example of the sensor electrodes E1 and E2.
In FIG. 34, the sensor electrode E1 is composed of two square conductors, the sensor electrode E2 is composed of one rectangular conductor, and the sensor electrode E1 is sandwiched between the sensor electrode E2 and the conductor. .
The center of gravity of the sensor electrode E1 and the center of gravity of the sensor electrode E2 are substantially the same. Further, the area of the sensor electrode E1 is equal to the area of the sensor electrode E2. The sensor electrodes E1 and E2 are symmetric with respect to two or more symmetry planes passing through the center of gravity.

FIG. 43 is a diagram illustrating an example of the sensor electrodes E1 and E2.
In FIG. 43, the sensor electrode E1 is composed of three triangular conductors, the sensor electrode E2 is composed of three triangular conductors, and these are alternately arranged so as to form a hexagon as a whole.

The center of gravity of the sensor electrode E1 and the center of gravity of the sensor electrode E2 are substantially the same. Further, the area of the sensor electrode E1 is equal to the area of the sensor electrode E2. The sensor electrodes E1 and E2 are symmetric with respect to two or more symmetry planes passing through the center of gravity.
In addition, this invention is not limited to the said embodiment, A various deformation | transformation is possible.

1 is a circuit diagram showing a capacitance detection device according to a first embodiment of the present invention. It is a figure which shows the A section of FIG. 3 is a timing chart for explaining the operation of the capacitance detection device of FIG. 1. It is a circuit diagram which shows the electrostatic capacitance detection apparatus which concerns on the 2nd Embodiment of this invention. It is a figure which shows the A section of FIG. It is a timing chart for demonstrating operation | movement of the electrostatic capacitance detection apparatus of FIG. It is a circuit diagram which shows the electrostatic capacitance detection apparatus which concerns on the 3rd Embodiment of this invention. It is a circuit diagram which shows the electrostatic capacitance detection apparatus which concerns on the 4th Embodiment of this invention. It is a circuit diagram which shows the electrostatic capacitance detection apparatus which concerns on the 5th Embodiment of this invention. It is a circuit diagram which shows the other example of the electrostatic capacitance detection apparatus which concerns on the 5th Embodiment of this invention. It is a circuit diagram which shows the other example of the electrostatic capacitance detection apparatus which concerns on the 5th Embodiment of this invention. It is a figure which shows the A section of FIGS. It is a timing chart for demonstrating operation | movement of the electrostatic capacitance detection apparatus of FIGS. It is a circuit diagram which shows the electrostatic capacitance detection apparatus which concerns on the 6th Embodiment of this invention. It is a circuit diagram which shows the other example of the electrostatic capacitance detection apparatus which concerns on the 6th Embodiment of this invention. 16 is a timing chart for explaining the operation of the capacitance detection device of FIGS. 16 is another timing chart for explaining the operation of the capacitance detection device of FIGS. It is a circuit diagram which shows the electrostatic capacitance detection apparatus which concerns on the 7th Embodiment of this invention. It is a circuit diagram which shows the other example of the electrostatic capacitance detection apparatus which concerns on the 7th Embodiment of this invention. It is a figure which shows the A section of FIG. FIG. 20 is a timing chart for explaining the operation of the capacitance detection device of FIGS. 18 and 19. FIG. FIG. 20 is another timing chart for explaining the operation of the capacitance detection device of FIGS. 18 and 19. FIG. It is a circuit diagram which shows the electrostatic capacitance detection apparatus which concerns on the 8th Embodiment of this invention. It is a circuit diagram which shows the other example of the electrostatic capacitance detection apparatus which concerns on the 8th Embodiment of this invention. It is a circuit diagram which shows the other example of the electrostatic capacitance detection apparatus which concerns on the 8th Embodiment of this invention. It is a figure which shows the A section of FIGS. It is a timing chart for demonstrating operation | movement of the electrostatic capacitance detection apparatus of FIGS. It is a circuit diagram which shows the electrostatic capacitance detection apparatus which concerns on the 9th Embodiment of this invention. It is a circuit diagram which shows the other example of the electrostatic capacitance detection apparatus which concerns on the 9th Embodiment of this invention. 30 is a timing chart for explaining the operation of the capacitance detection device of FIGS. 30 is another timing chart for explaining the operation of the capacitance detection device of FIGS. It is a circuit diagram which shows the electrostatic capacitance detection apparatus which concerns on the 10th Embodiment of this invention. It is a circuit diagram which shows the other example of the electrostatic capacitance detection apparatus which concerns on the 10th Embodiment of this invention. It is a figure which shows the A section of FIG. It is a timing chart for demonstrating operation | movement of the electrostatic capacitance detection apparatus of FIG. It is another timing chart for demonstrating operation | movement of the electrostatic capacitance detection apparatus of FIG. It is a figure which shows an example of sensor electrode E1, E2. It is a figure which shows an example of sensor electrode E1, E2. It is a figure which shows an example of sensor electrode E1, E2. It is a figure which shows an example of sensor electrode E1, E2. It is a figure which shows an example of sensor electrode E1, E2. It is a figure which shows an example of sensor electrode E1, E2. It is a figure which shows an example of sensor electrode E1, E2. It is a figure which shows the conventional electrostatic capacitance detection apparatus. It is a timing chart explaining operation | movement of the electrostatic capacitance detection apparatus of FIG.

Explanation of symbols

10, 20, 40, 50, 60, 70, 80, 90, 100, 110... Capacitance detection device 11, 21... First operational amplifier 31. Comparator 13, 23 ... first reference capacitor 14, 24 ... first open / close switch 15, 25 ... second open / close switch 16, 26 ... third open / close switch 17, 37 ..Control unit (switch control means, count means, determination means)
33 ... Second reference capacity 34 ... Fourth open / close switch 35 ... Fifth open / close switch 36 ... Sixth open / close switch 41 ... Seventh open / close switch 42 ... First 8 open / close switch 43... 1st correction capacitor 51... 7th open / close switch 52... 8th open / close switch 53. ... Eighth open / close switch 56 ... Second correction capacitor 63 ... Open / close switch (first potential supply circuit)
64 .. Open / close switch (second potential supply circuit)
93. Open / close switch (third potential supply circuit)
94. Open / close switch (fourth potential supply circuit)
E1 ... 1st sensor electrode E2 ... 2nd sensor electrode E0 ... Conductor Es1 ... 1st shield member Es2 ... 2nd shield member Eso1 ... 1st exterior Shield member Eso2 ... second outer shield member V1 ... first power supply potential V2 ... second power supply potential V3 ... first fixed potential V5 ... second fixed potential V6. ..First correction potential V7 ... Second correction potential

Claims (13)

A first differential amplifier having an inverting input terminal, a non-inverting input terminal, and an output terminal, the first fixed potential being input to the non-inverting input terminal;
A first reference capacitor having one electrode connected to the inverting input terminal of the first differential amplifier and the other electrode connected to the output terminal of the first differential amplifier;
A first open / close switch having one end connected to the inverting input terminal of the first differential amplifier and the other end connected to the output terminal of the first differential amplifier;
A second open / close switch having one end connected to the inverting input terminal of the first differential amplifier;
A third open / close switch having one end connected to the other end of the second open / close switch and the other end connected to a first power supply potential;
A first sensor electrode which is connected to the other end of the second open / close switch and forms a capacitor which faces a substantially constant potential conductor and exhibits a capacitance according to the distance from the conductor; ,
A second switch operation for closing the first open / close switch and then opening the first open / close switch and then returning the open / close switch to the open state after closing the second open / close switch; Switch control means for alternately repeating the third switch operation for returning the open state to the open state after closing the third open / close switch;
A comparator that has one input terminal connected to the output terminal of the first differential amplifier and compares the output voltage of the first differential amplifier with the voltage input to the other input terminal;
Counting means for counting the number of times the second switch operation is repeated;
Based on the number of times of the second switch operation counted by the counting means until the level of the input voltage at both input terminals of the comparator is inverted, the static between the first sensor electrode and the conductor is determined. Determining means for determining a change in electric capacity;
An electrostatic capacity detection device comprising:   2. The electrostatic capacitance according to claim 1, wherein a voltage input to the other input terminal of the comparator is opposite in phase to a voltage input to the one input terminal of the comparator. Detection device. A fourth open / close switch having one end connected to the inverting input terminal of the first differential amplifier;
A first correction capacitor having one electrode connected to the other end of the fourth open / close switch and the other electrode connected to a first correction potential;
A fifth open / close switch having one end connected to the other end of the fourth open / close switch and the other end connected to the first correction potential;
The switch control means opens and closes the fourth open / close switch at the same timing as the second open / close switch, and opens and closes the fifth open / close switch at the same timing as the third open / close switch.
The electrostatic capacitance detection apparatus according to claim 1. The first sensor electrode surrounds at least a part of the wiring connecting the first sensor electrode other than the surface facing the conductor and the first sensor electrode and the second and third open / close switches. A shielding member of
A first potential supply circuit that maintains the first shield member at the first fixed potential when at least the second opening / closing switch transitions from a closed state to an open state;
A second potential supply circuit for maintaining the first shield member at the first power supply potential when at least the third opening / closing switch transitions from a closed state to an open state;
The capacitance detection device according to claim 1, further comprising: A first current detection circuit connected between the first potential supply circuit and the first shield member;
First potential applying means for applying a potential different from the first power supply potential to the first shield member during a predetermined period when the third open / close switch is closed;
The capacitance detection device according to claim 4, comprising: At least one of the first sensor electrode other than the surface facing the conductor, wiring connecting the first sensor electrode and the second and third open / close switches, and at least the first shield member A first outer shield member surrounding a portion;
The first outer shield member is set to a constant potential;
The electrostatic capacitance detection apparatus according to claim 4. A first differential amplifier having an inverting input terminal, a non-inverting input terminal, and an output terminal, the first fixed potential being input to the non-inverting input terminal;
A first reference capacitor having one electrode connected to the inverting input terminal of the first differential amplifier and the other electrode connected to the output terminal of the first differential amplifier;
A first open / close switch having one end connected to the inverting input terminal of the first differential amplifier and the other end connected to the output terminal of the first differential amplifier;
A second open / close switch having one end connected to the inverting input terminal of the first differential amplifier;
A third open / close switch having one end connected to the other end of the second open / close switch and the other end connected to a first power supply potential;
A first sensor electrode which is connected to the other end of the second open / close switch and forms a capacitor which faces a substantially constant potential conductor and exhibits a capacitance according to the distance from the conductor; ,
A second differential amplifier having an inverting input terminal, a non-inverting input terminal, and an output terminal, the second fixed potential being input to the non-inverting input terminal;
A second reference capacitor having one electrode connected to the inverting input terminal of the second differential amplifier and the other electrode connected to the output terminal of the second differential amplifier;
A fourth open / close switch having one end connected to the inverting input terminal of the second differential amplifier and the other end connected to the output terminal of the second differential amplifier;
A fifth open / close switch having one end connected to the inverting input terminal of the second differential amplifier;
A sixth open / close switch having one end connected to the other end of the fifth open / close switch and the other end connected to a second power supply potential;
A second sensor electrode which is connected to the other end of the fifth open / close switch and forms a capacitor which faces the conductor and exhibits a capacitance according to the distance from the conductor;
After performing the first switch operation for opening the first open / close switch and the fourth open / close switch after closing the first open / close switch and the fourth open / close switch, the second open / close switch and the fifth open / close switch are closed. Switch control means for alternately repeating a second switch operation for returning to the open state and a third switch operation for returning the open state to the open state after closing the third open / close switch and the sixth open / close switch;
One input terminal is connected to the output terminal of the first differential amplifier and the other input terminal is connected to the output terminal of the second differential amplifier, and the output voltage of the first differential amplifier is A comparator for comparing the output voltage of the second differential amplifier;
Counting means for counting the number of times the second switch operation is repeated;
Based on the number of times of the second switch operation counted by the counting means until the level of the input voltage at both input terminals of the comparator is inverted, at least one of the first sensor electrode and the second sensor electrode. Determining means for determining a change in capacitance between one and the conductor;
An electrostatic capacity detection device comprising: A seventh open / close switch having one end connected to the inverting input terminal of the first differential amplifier;
A first correction capacitor having one electrode connected to the other end of the seventh open / close switch and the other electrode connected to a first correction potential;
An eighth open / close switch having one end connected to the other end of the seventh open / close switch and the other end connected to the first correction potential;
A ninth open / close switch having one end connected to the inverting input terminal of the second differential amplifier;
A second correction capacitor having one electrode connected to the other end of the ninth open / close switch and the other electrode connected to a second correction potential;
A tenth open / close switch having one end connected to the other end of the ninth open / close switch and the other end connected to the first correction potential;
The switch control means opens and closes the seventh open / close switch and the ninth open / close switch at the same timing as the second open / close switch and the fifth open / close switch, and the eighth open / close switch and the tenth open / close switch. Open and close at the same timing as the third open / close switch and the sixth open / close switch,
The electrostatic capacitance detection apparatus according to claim 7. The first sensor electrode surrounds at least a part of the wiring connecting the first sensor electrode other than the surface facing the conductor and the first sensor electrode and the second and third open / close switches. A shielding member of
A first potential supply circuit that maintains the first shield member at the first fixed potential when at least the second opening / closing switch transitions from a closed state to an open state;
A second potential supply circuit for maintaining the first shield member at the first power supply potential when at least the third opening / closing switch transitions from a closed state to an open state;
A second surrounding the surface of the second sensor electrode other than the surface facing the conductor and at least a part of the wiring connecting the second sensor electrode and the fifth and sixth open / close switches. A shield member of
A third potential supply circuit that maintains the second shield member at the second fixed potential when at least the fifth open / close switch transitions from a closed state to an open state;
A fourth potential supply circuit for maintaining the second shield member at the second power supply potential when at least the sixth open / close switch transits from a closed state to an open state;
The capacitance detection device according to claim 7, further comprising: A first current detection circuit connected between the first potential supply circuit and the first shield member;
First potential applying means for applying a potential different from the first power supply potential to the first shield member during a predetermined period when the third open / close switch is closed;
A second current detection circuit connected between the third potential supply circuit and the second shield member;
Second potential applying means for applying a potential different from the second power supply potential to the second shield member during a predetermined period when the fourth open / close switch is closed;
The capacitance detection device according to claim 9, further comprising: At least one of the first sensor electrode other than the surface facing the conductor, wiring connecting the first sensor electrode and the second and third open / close switches, and at least the first shield member A first outer shield member surrounding a portion;
At least one of a surface of the second sensor electrode other than the surface facing the conductor, a wiring connecting the second sensor electrode and the fifth and sixth open / close switches, and at least the second shield member A second outer shield member surrounding the part,
The first outer shield member and the second outer shield member are set to an arbitrary constant potential,
The electrostatic capacitance detection apparatus according to claim 9.   The area of the first sensor electrode and that of the second sensor electrode are equal, and the center of gravity of the first sensor electrode and the center of gravity of the second sensor electrode substantially coincide with each other. Capacitance detection device.   The capacitance detection device according to claim 12, wherein the first sensor electrode and the second sensor electrode are arranged symmetrically with respect to two or more planes passing through the center of gravity.

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