JP2002277280A - Position detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a specified position of a measuring portable unit with a plate shape which moves on a plain face by phase detection using a capacitance element and resistance element with noncontacting. SOLUTION: A capacitance element is formed with two electrodes that are provided so as to parallel the platy and conductive measuring portable unit with a slit at the specified position. A delay circuit is contracted with a resistance element that is connected to two resistance elements, to which two alternating current signals with different phases are respectively applied. A phase and a gain change when the slit of the measuring portable unit passes on the two electrodes are detected with a time constant for a resistance value and a capacitance value as an equal value with a period of the alternating current signals, and the pass of the measuring portable unit is detected by rectifying a variation by a differentiating circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring mobile unit in which a plurality of AC signals having different initial phases have exclusive dielectric constants at specified portions, and a plurality of electrodes parallel to the measuring mobile unit. The present invention relates to a device for non-contact detection of a specified position of a measurement moving body by a change in electric field strength of a capacitive element, and to phase detection from a plurality of AC signals.

[0002]

2. Description of the Related Art A capacitive element is formed having a measuring moving body which is a plate-like conductor, two signal electrodes parallel to the measuring moving body, and one counter electrode, and measurement is performed between the electrodes. A position detection device that inserts a moving body for measurement and detects a leaked electric field from a slit or the like provided at a specific position on the moving body for measurement. This is a configuration for detecting.

FIG. 3 shows a position detecting device. In order to detect passage through the specified position of the measurement movable body 118 which is a plate-shaped conductor, the first signal electrode 304 which is parallel to, is opposed to, and is adjacent to the plate-shaped measurement movable body 118 A second signal electrode 308 is provided, and another counter electrode 324 is provided on the other side so as to face the two signal electrodes to form a capacitive element. In the phase detection device having a structure to be inserted, a first AC signal 138 and a second signal electrode 3
08, a second AC signal 142 having a different initial phase from the first AC signal 138 is applied. A slit 122 is provided in the plate-like measurement moving body 118, and a leakage electric field from the slit 122 when passing over the electrode causes a counter electrode 324 to be formed.
To obtain a composite signal.

FIG. 3 shows that the moving body for measurement 118 is a disk-shaped rotating body, and a slit 122 is opened at a specified position of the moving body for measurement 118. When the specified position of the slit 122 approaches the first signal electrode 304, the first AC signal 138 is capacitively coupled to the signal to the counter electrode 324 due to a change in the intensity of the leakage electric field, and the slit 122 is completely removed. When the first signal electrode 304 reaches the first signal electrode 304, the signal propagation reaches its maximum, and when the moving body 118 for measurement further rotates, the signal propagation decreases.

Similarly, when approaching the other second signal electrode 308, the second AC signal 1
42, the amplitude increases or decreases due to the signal propagation.

A first AC signal 138 for transmitting a signal
Between the signal electrode 304 and the second signal electrode 308 that generates the second AC signal 142 is the same as the opening size in the moving direction of the slit 122 such as a hole provided in the measurement moving body 118. Or less.

In FIG. 3, the first AC signal 138 and the second AC signal 142 are generated along with the rotation of the measuring movable body 118.
The signal is propagated to the opposing counter electrode 324, and the two AC signals are combined.

The signal synthesized by the counter electrode 324 has a phase component of the first AC signal 138 and the second AC signal 142, and the synthesized signal is appropriately amplified by the amplifier 312.
After that, in the processing circuit 316, the composite wave amplified by the amplifier 312 and the first AC signal 138 or the second AC signal 142 are AND-processed, and the phase component of the first AC signal 138 is further processed. By dividing it into the phase component of the second AC signal 142, the amount of change in the phase component in the composite signal is detected.

[0009] The amount of phase change obtained by the processing circuit 316 is weighted to positive and negative potentials, and rectified to obtain a DC potential change. Is detected.

Therefore, the first signal electrode 304 and the second signal electrode 308 reduce the leakage electric field intensity of the first AC signal 138 and the second AC signal 142 with respect to the opening of the slit 122. It is necessary to arrange such that the increase of the leakage electric field strength overlaps.

When the opening of the slit 122 is far from the first signal electrode 304 and the second signal electrode 308, the rectified signal causes the counter electrode 324 to move the electrically-grounded measurement moving body 118. Since the capacitive element is a counter electrode, there is no AC component in theory, but it actually has a noise component and has an unnecessary bias component when rectified from AND processing.

[0012]

A capacitive element is formed having a measuring moving body which is a plate-shaped conductor, two signal electrodes parallel to the measuring moving body, and one counter electrode. In a position detection device that inserts a measurement moving body between the electrodes and detects a leakage electric field from a slit or the like provided at a specific position of the measurement moving body, the S / N ratio at the counter electrode may decrease, On the other hand, if the aspect ratio is high and the capacitance value is low, a sufficient amplitude change due to the transmission and reception of the AC signal cannot be obtained, and unnecessary bias components increase when detecting a phase change.

The electric fields of two AC signals having different initial phases, which are capacitively coupled from the two signal electrodes, are combined by the counter electrode, but are applied to the receiving electrode of the capacitive element which is not shielded and sealed. Includes the wiring connected to it,
It is inevitable that noise components appear.

When the effective area of the counter electrode is increased,
The noise component also increases, and the unnecessary bias component when rectifying after the AND processing increases. Also, two signal electrodes,
The thickness of the plate-shaped measurement moving body inserted between the opposed electrodes is
Since it is directly related to the distance between the electrodes of the capacitive element, it is necessary to limit the thickness of the measuring movable body in order to secure the capacitance value.

Further, it is necessary to consider a dimensional tolerance of a margin for avoiding contact between the measurement moving body and the two signal electrodes and the counter electrode.

Since the noise component of the synthesized signal is reduced and the unnecessary bias at the time of rectification is reduced, and the measures for securing the thickness of the movable body for measurement and securing the capacitance value are contrary to each other, the optimum value for the detection is specified. Or difficult to adjust.

An object of the present invention is to solve the above problems without detecting a phase from a composite signal of a counter electrode.
An object of the present invention is to provide a position detection circuit for detecting a phase from only two signal electrodes.

[0018]

In order to achieve the above object, a position detecting circuit device of the present invention employs the following configuration.

A plurality of signal electrodes each having a capacitive element for receiving the first AC signal and a capacitive element for receiving the second AC signal, and a measuring movable body moving in parallel with the plurality of signal electrodes. In the position detection device configured to provide a specific portion having a different dielectric constant to the measurement moving body and to detect a change in electric field intensity accompanying the movement of the measurement moving body, the measurement moving body may be an electric conductor. And the plurality of signal electrodes are composed of a first signal electrode and a second signal electrode facing each other on one surface of the measurement moving body, and are connected to the first signal electrode via a first resistance element. An AC signal is applied, and a second AC signal having an initial phase different from that of the first AC signal is applied via a second resistive element, and the first signal electrode and the second AC signal are applied.
A first capacitance element formed between the first signal electrode and the measurement moving body from a capacitance value change between the measurement moving body when the signal electrode passes through the specific portion; A signal that is phase-modulated by a circuit constituted by the first resistance element is detected, and a second capacitance element formed between the second signal electrode and the measurement moving body is connected to the second capacitance element. It is characterized in that a signal phase-modulated by a circuit composed of a resistance element is detected.

The time constant determined by the first capacitance element and the first resistance element, and the time constant determined by the second capacitance element and the second resistance element
Each of the time constants determined by the resistance elements is substantially the same as the fundamental frequency of the first AC signal and the second AC signal.

A plurality of signal electrodes forming a capacitive element for receiving the first AC signal and a capacitive element for receiving the second AC signal, and a measuring movable body moving in parallel with the plurality of signal electrodes. A position detecting device configured to provide a specific portion having a different dielectric constant to the measurement moving body, and to detect a change in electric field intensity accompanying movement of the measurement moving body, wherein the plurality of signal electrodes are A first electrode group composed of a pair of a first signal electrode facing one surface of the body and a second signal electrode facing the other surface, and one surface of the measurement moving body. A second electrode group includes a pair of an opposing third signal electrode and an opposing fourth signal electrode on the other surface, and the first signal electrode of the first electrode group includes a second electrode group. A first AC signal is applied via the first resistance element, and the second AC signal is applied to the second AC signal. A second AC signal having a different initial phase from the first AC signal is applied to a third signal electrode of the pole group via a second resistance element, and a second signal electrode of the first electrode group is applied. To which the first AC signal is directly applied,
The second AC signal is directly applied to the fourth signal electrode of the second electrode group to form a parallel circuit, and the specific portion passes through the first electrode group and the second electrode group. Detecting a signal phase-modulated by the first capacitance element formed by the first electrode group and the first resistance element from a capacitance value change between the measurement moving body and A signal phase-modulated by a second capacitance element formed by the second electrode group and the second resistance element is detected.

The measurement moving body is a conductor, and is electrically grounded, and the conductor portion of the measurement moving body is
It is characterized by being inserted between the first electrode group and between the second electrode groups to cut off AC coupling of the capacitor.

The parallel circuit includes a reciprocal of a time constant defined by a capacitance value of the first capacitance element and a resistance value of the first resistance element, and a capacitance value of the second capacitance element and the second capacitance element.
The reciprocal of the time constant determined by the resistance value of the resistor element is substantially the same as the angular frequency of the fundamental frequency of the first AC signal and the angular frequency of the fundamental frequency of the second AC signal. It is characterized by the following.

[0024]

FIG. 1 is an explanatory diagram showing the structure and circuit configuration of a position detecting circuit device according to a first embodiment of the present invention. FIG. 2 is a diagram showing the structure and circuit structure of the position detecting circuit device according to a second embodiment of the present invention. FIG. 3 is an explanatory diagram illustrating a circuit configuration.

FIG. 1 shows a position detecting circuit device according to a first embodiment of the present invention. The first signal electrode 110 and the second signal electrode 114 are structurally arranged adjacent to each other on a plane. The measurement moving body 118 which is a conductor and the two signal electrodes 110 and 114 are parallel to each other, and the measurement moving body 118 is provided with a slit 122 having a feature with a different dielectric constant or a hole at a specified position. FIG. 1 shows that the measurement moving body 118 rotates in a disk shape. The slit 122 has a structure passing over the two signal electrodes 110 and 114.

In terms of circuit, the first AC signal 138 is applied to each of the first signal electrode 110 and the second signal electrode 114.
Then, the second AC signal 142 is supplied from the resistance element 126. The moving body for measurement 118 is a conductor and is electrically grounded, and forms a capacitive element with the two signal electrodes 110 and 114 respectively. The nodes of the two signal electrodes 110 and 114 are appropriately amplified by an amplifier 134, respectively, and the amplified signal is processed by a processing circuit 140 into a first AC signal 318, a second AC signal 142, and an AND signal.
After the processing, the amount of phase displacement is extracted.

The position detecting circuit 148 separates the phase displacement amount extracted by the processing circuit 140 into a phase component of the first AC signal 138 and a phase component of the second AC signal 142,
After weighting and rectifying the positive and negative potentials, a potential change point is detected by a differentiating circuit or the like (not shown).

The resistance element 126 shown in FIG. 1, the measuring movable body 118 which is a conductor, the first signal electrode 110 and the second
It is necessary to set the time constant of the first AC signal 138 and the period of the second AC signal 142 to substantially the same value as the time constant of the capacitor formed from the signal electrode 114.

When the slit 122 provided in the measurement moving body 118 is far from each of the two signal electrodes 110 and 114, the first AC signal 138 and the second AC Signal 142
A signal with a more delayed phase is obtained.

When the slit 122 provided on the measuring moving body 118 passes over the two signal electrodes 110 and 114, the slit 122 of the measuring moving body 118 facing the respective signal electrodes 110 and 114 When the effective electrode area of the capacitor increases or decreases, which causes a change in the capacitance, the time constant of the delay circuit changes and the phase of the signal changes.

After amplifying the signal having the phase change and performing impedance conversion, the two amplified signals are converted into a first AC signal 138 and a second AC signal 142.
After performing AND processing on each of them and extracting a phase change amount, rectification results in a change in bias potential.

The first AC signal 138 supplied to the two signal electrodes 110 and 114 and the second AC signal 142 are
It is desirable that signals having different initial phases and the same frequency be used, the phase change amount of each AC signal can be detected largely, and the point at which the rising transition period and the falling transition period intersect is detected.

Therefore, it is also essential to ensure the absolute amount of the change in capacitance. The distance between the plate-like measuring moving body 118 and the signal electrodes 110 and 114 arranged adjacent to each other on two planes is determined by the following formula. It is desirable to be close.

FIG. 2 shows a position detecting device according to a second embodiment of the present invention, in which a first signal electrode 204, a second signal electrode 208, a third signal electrode 212 and a fourth signal electrode 216 are paired. Are arranged side by side on a plane to form adjacent capacitive elements,
A pair of signal electrodes and a moving body for measurement 11 which is a plate-like conductor
8 are parallel to each other, and the measurement moving body 118 has a structure inserted between the capacitance elements.

The measurement moving body 118 is provided with slits 122 such as features or holes having different dielectric constants at specified positions, and FIG. 2 shows that the measurement moving body 118 rotates in a disk shape. I have. The slit 122 of the moving body for measurement 118 has a structure that passes between capacitive elements formed of two pairs of signal electrodes by a rotation operation.

In terms of circuit, the first signal electrode 204 and the second signal electrode 208 which are a pair of the first electrode group, and the third signal electrode 212 and the fourth signal electrode which are the second electrode group are paired. The first signal electrode 204 and the third signal electrode 212 on one side of the capacitive element composed of the
Signal 138 and the second AC signal 142 are supplied from the resistance element 231 and the other second signal electrode 208
The first AC signal 1 is applied to each of the
38 and a second AC signal 142 are provided directly. The measurement moving body 118 which is a conductor is electrically grounded.

The first AC signal 138 and the second AC signal 142 shown in FIG. 2 are signals having the same frequency but different initial phases, and include two resistance elements 231 and a pair of signal electrodes 20.
4 and 208 and the time constant of the capacitor formed from the signal electrodes 212 and 216 are set to be substantially the same as the reciprocal of the angular frequency of the first AC signal 138 and the second AC signal 142. It is necessary to.

When the slit 122 provided in the measurement moving body 118 is far from each of the capacitive elements composed of two pairs of signal electrodes, the capacitive elements are connected to the signal electrodes 204 and 212 on one side of each of the capacitive elements and electrically. Since the capacitive element is formed by the measurement moving body 118 that is grounded, a delay circuit is formed.

When the slit 122 provided in the measuring movable body 118 passes over the signal electrodes of the two pairs of capacitive elements,
Due to the slit 122 of the moving body for measurement 118, the effective electrode area of the capacitance between the signal electrode and the moving body for measurement 118 increases and decreases, while, between the signal electrodes forming two pairs of the respective capacitive elements, The capacitance value increases or decreases due to the leakage electric field from the slit. When the slit 122 is far from the two pairs of capacitive elements, a delay circuit is configured. When the slit 122 is on the signal electrode of the capacitive element, a parallel circuit is configured. At the nodes, a phase change of the first AC signal and a phase change of the second AC signal are obtained.

The signal having this phase component is supplied to an amplifier 238.
, And impedance-converted, the two amplified signals are processed by a processing circuit 240 into a first AC signal 138, a second AC signal 142, and
After the processing, the phase component of the first AC signal and the phase component of the second AC signal are separated, and the position
By weighting the two phase components with positive and negative potentials and rectifying them, a change in bias potential can be obtained.

The first AC signal 138 and the second AC signal 142 supplied to the two signal electrodes 110 and 114 are:
It is desirable that signals having different initial phases and the same frequency be used, the phase change amount of each AC signal can be detected largely, and the point at which the rising transition period and the falling transition period intersect is detected.

Therefore, it is also essential to secure the absolute amount of the capacitance change.
It is desirable that the thickness is extremely thin,
A first signal electrode 204 and a second signal electrode 204 are arranged on two planes.
Signal electrode 208, the third signal electrode 212 and the fourth
Is desirably close to the signal electrode 216.

[0043]

According to the position detecting device of the present invention, a capacitance element is formed by a plurality of signal electrodes, and a resistance element and a delay circuit or a parallel circuit are formed. It is possible to obtain a phase modulation signal for detection.

Since the distance in the direction of the electric field that is not shielded and sealed is absolutely smaller than that in the case of detecting a composite signal by capacitively coupling a plurality of AC signals from the leakage electric field due to the slit between the capacitive elements, The inter-electrode noise can be reduced, and the phase signal and the gain are directly changed by utilizing the phase modulation of the AC signal due to the change in the capacitance value. Can be taken high.

Since the capacitance element is formed between the moving object for measurement and the signal electrode, the aspect ratio can be determined by the distance between the moving object for measurement, the distance between the signal electrodes, and the area of the signal electrode, and the thickness of the moving object for measurement becomes the capacitance value. Become irrelevant. For this reason, a large change in the capacitance value can be obtained, and the phase change amount per movement displacement amount of the measurement moving body is large.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a position detection circuit device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a position detection circuit device according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a position detection circuit device in a conventional example.

[Explanation of symbols]

 110 first signal electrode 114 second signal electrode 118 moving body for measurement 122 slit 126 resistive element 138 first AC signal 142 second AC signal

Claims (5)

[Claims] A capacitor for receiving a first AC signal;
A plurality of signal electrodes each having a capacitive element for receiving an AC signal, and a measurement moving body that moves in parallel with the plurality of signal electrodes, and the signal electrodes are moved with the movement of the measurement moving body. In the position detecting device for providing a specific portion that causes a capacitance change between the measurement moving body and the electric field intensity change accompanying the movement of the measurement moving body, the measurement moving body is an electric conductor. The plurality of signal electrodes are composed of a first signal electrode and a second signal electrode which are opposed to each other on one surface of the measurement moving body, and are connected to the first signal electrode via a first resistance element. And applying a second AC signal having an initial phase different from that of the first AC signal via a second resistive element, and applying the first signal electrode and the second
A first portion formed between the first signal electrode and the measurement movable body when the specific portion passes over the signal electrode of
Detecting a signal phase-modulated by a circuit composed of the capacitive element and the first resistive element,
A position detection device which detects a signal phase-modulated by a circuit including a second capacitance element and the second resistance element formed between the signal electrode and the measurement moving body. 2. A time constant determined by the first capacitance element and the first resistance element and a time constant determined by the second capacitance element and the second resistance element are all the first AC signal. 2. The position detecting device according to claim 1, wherein the period is substantially equal to a period of a fundamental frequency of the second AC signal. 3. A capacitor for receiving a first AC signal and a second capacitor for receiving a first AC signal.
A plurality of signal electrodes each having a capacitive element for receiving an AC signal, and a measurement moving body that moves in parallel with the plurality of signal electrodes, and a specific portion having a different dielectric constant from the measurement moving body. Wherein the plurality of signal electrodes are opposed to each other on one surface of the measurement moving body.
A first electrode group composed of a pair of second signal electrodes facing one another on the other surface, and a third signal electrode facing the other surface on one surface of the moving object for measurement. The second signal group comprises a pair of fourth signal electrodes facing each other on the surface, and the first signal electrode of the first electrode group is connected to the first signal electrode via a first resistive element. And applying a second AC signal having a different initial phase from the first AC signal to a third signal electrode of the second electrode group via a second resistance element. The first AC signal is directly applied to the second signal electrode of the first electrode group, and the second AC signal is directly applied to the fourth signal electrode of the second electrode group. A parallel circuit is formed, and when the specific portion passes over the first electrode group and the second electrode group, A first capacitor formed by a first electrode group and a signal phase-modulated by the first resistor are detected, and a second capacitor formed by the second electrode group and the second capacitor are detected. A position detecting device for detecting a signal phase-modulated by the second resistance element. 4. The moving object for measurement is a conductor,
Electrically grounded, the conductor portion of the measurement moving body is inserted between the first electrode group and between the second electrode group, and cuts off AC coupling of the capacitive element. The position detecting device according to claim 3. 5. The parallel circuit includes: a reciprocal of a time constant defined by a capacitance value of the first capacitance element and a resistance value of the first resistance element; and a capacitance value of the second capacitance element and the second capacitance element. The reciprocal of the time constant determined by the resistance value of the resistance element 2 is
5. The position according to claim 3, wherein the angular frequency of the fundamental frequency of the first AC signal is substantially equal to the angular frequency of the fundamental frequency of the second AC signal. 6. Detection device.