JPH095015A - Sensor of capacitance type - Google Patents

Abstract

PURPOSE: To provide a compact and accurate sensor of capacitance type capable of outputting electric signal. CONSTITUTION: This sensor is composed of fixed electrodes 11, 12, a movable electrode 13 disposed apart from the electrodes 11, 12 at a specified space so that it may not come into contact therewith while being insulation-supported rotatably by a first shaft 14, a means 17 for converting into a signal the capacitance generated between the electrodes 11, 12 and the electrodes 13. At least one of the electrodes 11, 12 is formed on the surface of insulator while the means 17 is disposed on the other surface thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contactless capacitance type sensor for detecting a rotation angle or the like based on a variation amount of capacitance.

[0002]

2. Description of the Related Art A conventional contactless capacitance type sensor of this type will be described in detail with reference to FIG. In FIG. 4, the capacitance type sensor has fixed electrodes 1 and 2 and a movable electrode 3.
And a conversion means 7 for converting the capacitance into a frequency or a voltage.

The variable capacitor section 6 is arranged such that a first fixed electrode 1 and a second fixed electrode 2 having a substantially fan-shaped electrode structure face each other, and are rotated by an insulating shaft 4 between them. A movable electrode 3 having a substantially fan-shaped electrode structure supported as much as possible is inserted and arranged.

The first fixed electrode 1 has a pair of electrode structures composed of first and second divided electrodes 1a and 1b insulated from each other, and is formed on the facing surface of the movable electrode 3. The second fixed electrode 2 also has a pair of electrode structures composed of first and second divided electrodes 2 a and 2 b which are insulated from each other, and is formed on the facing surface of the movable electrode 3. Then, the fixed electrodes 1 and 2
Are insulated and fixed to the main body (not shown) of the capacitance type sensor at a predetermined interval. The fixed electrodes 1 and 2
May be connected to the sensor body so as to be conductive, and the sensor body may be connected to the ground side.

The movable electrode 3 has a pair of electrode structures composed of first and second divided electrodes 3a and 3b which are electrically connected to each other, and is spaced from the fixed electrodes 1 and 2 by a predetermined distance so as not to contact each other. The movable electrode 3 is fixed to the insulating shaft 4, and is rotatably supported by the main body by the insulating shaft 4.

One end of each of the output terminals 5 and 5 has a fixed electrode 1 or 2.
The first divided electrodes 1a, 2a and the second divided electrodes 1b,
2b, and the other ends of the output terminals 5 and 5 are connected to the conversion means 7.

In the variable capacitor section 6 having such a configuration, the capacitance generated between the movable electrode 3 and the first divided electrodes 1a, 2a and the second divided electrodes 1b, 2b is equal to that of the movable electrode 3. It changes with the movement. The conversion means 7 has a circuit configuration capable of converting the capacitance of the variable capacitor section 6 into a frequency change, a voltage change, or the like.

[0008]

However, in the capacitance type sensor having such a structure, the variable capacitor section and the converting means are separate bodies, and it is difficult to downsize the capacitance type sensor. The work of electrically connecting the variable capacitor section and the conversion means is necessary, and a cable is used for conduction, the influence of noise due to the cable,
There are problems that the sensitivity decreases due to the increase of impedance, the response speed is delayed, and an abnormal value occurs.

An object of the present invention is to solve the above-mentioned problems, and it is an object of the present invention to provide a capacitance type sensor which is small in size and capable of outputting an electric signal with high accuracy.

[0010]

In order to achieve the above object, in the capacitance type sensor of the present invention, a fixed electrode is provided with a predetermined distance from the fixed electrode so as not to contact the fixed electrode. The movable electrode is disposed and is rotatably insulated and supported by a shaft, and a conversion unit that converts a capacitance generated between the fixed electrode and the movable electrode into a signal. One of them is formed on one surface of the insulating substrate, and the conversion means is arranged on the other surface of the insulator.

Further, the fixed electrode and the conversion means are electrically connected by a wiring path. Furthermore, the conversion means is configured to convert the capacitance into a voltage or a frequency.

[0012]

According to the present invention, with the above-mentioned configuration, the insulating substrate on which the fixed electrode is formed and the circuit substrate forming the electronic circuit of the converting means are made common, and the insulating substrate and the circuit substrate are also used. Since they are commonly used, a cable as a wiring path for electrically connecting the variable capacitor section and the conversion means is unnecessary.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described in detail with reference to FIGS. In FIG. 1, the electrostatic capacitance sensor is composed of a variable capacitor section 16 which is roughly composed of fixed electrodes 11 and 12 and a movable electrode 13, and a conversion means 17 which converts electrostatic capacity into a voltage.

The variable capacitor section 16 has a first fixed electrode 11 and a second fixed electrode 1 in which fixed electrodes 11 and 12 having a substantially fan-shaped electrode structure are arranged so as to face each other.
A movable electrode 13 having a substantially fan-shaped electrode structure rotatably supported by a first shaft 14 made of an insulator is inserted and arranged between the two.

The first fixed electrode 11 is, as shown in FIG. 2B, the first and second divided electrodes 11 which are insulated from each other.
It has a pair of electrode structures consisting of a and 11b, and is formed on the lower surface of the first insulating substrate 111. Second fixed electrode 12
Are the first and second divided electrodes 12a, which are insulated from each other.
It has a pair of electrodes 12b and is formed on the upper surface of the second insulating substrate 121. Then, the fixed electrodes 11, 1
2 is a base 21 of the capacitance type sensor made of an insulating material.
It is fixed at a predetermined interval.

The movable electrode 13 has a pair of electrode structures composed of first and second divided electrodes 13a and 13b which are electrically connected to each other, and the first and second electrodes are formed on both upper and lower surfaces of the third insulating substrate 131. Divided electrodes 13a and 13b are formed. The movable electrode 13 is spaced apart from the fixed electrodes 11 and 12 by a predetermined distance so as not to come into contact with each other.
The movable electrode 13 is insulated from the fixed electrodes 11 and 12, and is rotatably supported by the base 21 by the first shaft 14.

The fixed electrodes 11 and 12 and the movable electrode 13 are formed by providing a foil body made of metal or the like on the surfaces of the insulating substrates 111, 121 and 131. The variable capacitor section 16 having such a configuration includes the first divided electrodes 11a and 12a and the second divided electrodes 11b and 12 via the movable electrode 13.
The electrostatic capacitance generated between the movable electrode 13 and b changes by the rotation of the movable electrode 13, and the electrostatic capacitance is input to the conversion means 17.

Next, the conversion means 17 will be described. As shown in FIG. 2A, the conversion means 17 has the following electronic circuit on the upper surface of the first insulating substrate 111 together with the wiring path 171 made of a metal foil.

A more specific structure of the converting means 17 is shown in FIG.
As shown in FIG. 3, the oscillator 172, the modulator 173, and the demodulator 1
And an amplifier circuit section 175. The oscillating unit 172 oscillates a constant frequency serving as a reference, and the modulating unit 173 modulates the frequency, that is, changes the frequency in accordance with the capacitance change of the variable capacitor unit 16. Furthermore, the modulator 1
Demodulation unit 174 including an integrating circuit
Is converted to a voltage by the amplifier circuit 175, and this voltage is amplified to a predetermined magnitude by the amplification circuit section 175 and output as a voltage change.

Therefore, the conversion means 17 is formed on the upper surface of the first insulating substrate 111, and the first fixed electrode 11 is formed on the lower surface thereof. Next, the rotation support portion of the capacitance type sensor will be described. As shown in FIG. 1, the rotation supporting unit includes the base 21, the flange 22, and the second shaft 2.
3, comprising a bearing 24 and a metal case 25.

The base 21 is fixed to the flange 22 by the first bolt 26. The base 21 has a through hole 211 near the center thereof, and the bearing 2 is provided in the through hole 211.
4, 24 are provided. Further, the second shaft 23 is disposed inside the bearing 24, and as a result, the second shaft 23 is rotatably supported by the base 21.
To prevent the second shaft 23 from coming off in the rotation axis direction,
Attach the E-ring 27 to one of the shafts 23 of the
The bearings 24, 24 are sandwiched by screwing a nut 28 on the other side of the shaft 23.

The first shaft 14 holds the movable electrode 13 via an insulating spacer 29, and fixes one end of the first shaft 14 to the end of the second shaft 23 by press fitting or the like. Therefore, the movable electrode 13 is rotatably supported by the base 21 via the shaft composed of the first shaft 14 and the second shaft 23.

The insulating substrates 111 and 121 on which the fixed electrodes 11 and 12 are formed are fixed to the base 21 by the second bolts 31 via the metal spacers 30 (in FIG. 1, the metal spacers 30 and the second bolts). 31 is shown for each one, the others are not shown). By the metal spacer 30, the first
A predetermined space is provided between the fixed electrode 11 and the second fixed electrode 12, and the first divided electrodes 11a, 12a and the second divided electrodes 11b, 12b are electrically connected, respectively. Furthermore, the second bolt 31 electrically connects the first divided electrode 11a, the second divided electrode 12a, and the changing means 17.

The metal case 25 has a substantially cylindrical shape having an opening, and accommodates the fixed electrodes 11 and 12, the movable electrode 13, the converting means 17 and the base 21 and is fixed to the flange 22. An output terminal (not shown) is extended from the amplification section 175 of the conversion means 17 to the outside of the case 25 via the cable holding material 32.

The insulating substrates 111, 121, 131 are made of a glass epoxy resin substrate or a heat resistant synthetic resin, and the fixed electrodes 11, 12, the movable electrode 13 and the wiring path 17 are used.
1 may be formed by etching a printed circuit board.

The fixed electrodes 11 and 12 and the movable electrode 1
3 can also be formed by printing a conductive paste or by sputter deposition. In this case, the wiring path 171 of the first insulating substrate 111 and the first fixed electrode 11 can be electrically connected by forming a conduction electrode in the through hole 176.

Further, although the converting means 17 has been described by using the example of changing the electrostatic capacity into the voltage, the demodulating section 174 and the amplifying section 175 may be deleted and the modulating section 173 may output a signal as a frequency change. Good.

Furthermore, the variable capacitor section 16 has been described using an example in which there are two stages of fixed electrodes and movable electrodes are arranged between them, but the invention is not limited to this, and a predetermined amount of variable capacitance is provided. It goes without saying that the number of stages of fixed electrodes and the number of movable electrodes can be increased or decreased according to the above.

[0029]

As described above, in the capacitance type sensor according to the present invention, the variable capacitor section and the converting means are integrated, and the insulating substrate of the fixed electrode and the circuit board of the converting means are shared. In addition, the number of constituent members can be reduced, and the capacitance type sensor can be made smaller and thinner. Further, when using the capacitance type sensor, the assembly is easy.

Further, since it is possible to conduct electricity through the bolts or through holes without using a cable for conducting the fixed electrode and the converting means, there is no problem such as connection processing error or contact failure, and a highly reliable circuit. In addition, since the electrical connection between the fixed electrode and the conversion means is short, the capacitance type sensor that is not easily affected by noise and stray capacitance and has excellent sensitivity and accuracy can be obtained.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an embodiment of a capacitance type sensor according to the present invention.

FIG. 2 is a front view showing (a) converting means and a bottom view showing (b) fixed electrodes of a first insulating substrate 111.

FIG. 3 is a block diagram of conversion means.

FIG. 4 is a perspective view of a conventional main part.

[Explanation of symbols]

 11 1st fixed electrode 12 2nd fixed electrode 13 Movable electrode 14 1st shaft 17 Converting means 23 2nd shaft 111 1st insulating substrate

Claims (3)

[Claims] 1. A fixed electrode, a movable electrode disposed at a predetermined distance from the fixed electrode so as not to come into contact with the fixed electrode, and rotatably insulated and supported by a shaft, and the fixed electrode. And a conversion unit that converts a capacitance generated between the movable electrode and the movable electrode, wherein at least one of the fixed electrodes is formed on one surface of the insulating substrate, and the conversion unit is formed on the other surface of the insulator. An electrostatic capacitance type sensor characterized in that it is provided. 2. The capacitance type sensor according to claim 1, wherein the fixed electrode and the conversion means are electrically connected by a wiring path. 3. The conversion means converts the capacitance into a voltage or a frequency.
Alternatively, the capacitive sensor according to the item 2.