JPH07167604A - Position-detecting sensor in fine movement - Google Patents

Abstract

PURPOSE:To provide a position detection sensor which allows detecting position in a movement of 1mum or less. CONSTITUTION:The sensor consists of an electret 1 containing numerous charged electrons, with fine intervals, 4a, 4b,..., and a comb-like electrode 2, corresponding to the electret 1 with a specified spacing, wherein electric charge and discharge repeatedly occurring, due to induction from the charged electrons, on numerous teeth 5e, 5f,... provided at the positions facing the charged electrons at relative movement to the electret 1 is converted into potential change for position detection caused by relative movement, for outputting.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting sensor used in a speedometer, an encoder, etc.
The present invention relates to a fine position detection sensor capable of detecting a minute movement amount.

[0002]

2. Description of the Related Art FIG. 4 is a perspective view of a conventional linear gauge sensor. It is provided with a moving slit which moves integrally with a spindle and a fixed slit which is fixed at a fixed position. Using the position detection sensor with the transistor arranged, the phototransistor converts the light-dark change due to the movement of the moire fringes into an electric signal,
The position movement amount is measured from the output pulse corresponding to the number of slits.

[0003]

However, in such a conventional position detecting sensor, since the displacement amount of the slit plate is detected by the output pulse corresponding to the number of slits, the resolution is determined by the slit pitch. According to the conventional technology, the slit pitch is limited to about 4 to 10 μm, and it is impossible to improve the level to a fine level even when the signal processing technology such as signal interpolation processing is used together.
Further, even a system utilizing high-resolution optical diffraction can be miniaturized up to about 1 μm. Under these circumstances, there has been a problem in that it is not possible to meet the demands for high-resolution speedometers and encoders that enable particularly high-precision positioning and trajectory control that have recently been increasing.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a highly accurate fine position detecting sensor capable of making the resolution corresponding to the slit pitch fine to a molecular level of 1 μm or less. To do.

[0005]

In order to achieve the above object, the fine position detecting sensor of the present invention is a position detecting sensor used for a speedometer, an encoder, etc., and is charged at fine intervals. The electret having a large number of surface charges, and the charging / discharging that repeatedly occurs on a large number of comb teeth provided at a position facing the electret at a predetermined interval and facing the surface charge when horizontally moving relative to the electret. It is provided with a comb-teeth-shaped electrode that converts and outputs a potential change for detection.

Further, in a position detecting sensor used for a speedometer, an encoder, etc., a fine gap is provided at an exposed portion of the SiO ₂ layer separated by a metal film vapor deposition portion on the surface of the SiO ₂ layer deposited on a silicon wafer. A fixed electrode plate having a large number of charging electrodes formed thereon, and a large number of detection electrodes having the same intervals as the charging electrodes at a position facing the charging electrodes on a glass plate facing the fixed electrode plate at a predetermined interval. A moving electrode plate is provided which outputs a periodic voltage signal for position detection generated on the detection electrode when moving in the horizontal direction.

[0007]

According to the above structure, when there is relative movement in the horizontal direction between the comb-teeth-shaped electrode provided with the comb teeth and the electret at the position corresponding to the surface charge on the electret with the minute intervals charged, the movement is caused. Correspondingly, the charging / discharging that is repeatedly generated on the comb tooth due to the surface charge is converted into a potential change and output, so that fine position detection becomes possible.

Alternatively, the surface of the SiO ₂ layer on a silicon wafer is separated by a metal film, and the exposed portion is charged to form a large number of charging electrodes with fine intervals, and a glass plate is charged on the fixed electrode plate. A moving electrode plate, which is opposed to the electrode and has a large number of detection electrodes vapor-deposited at the same interval, is installed so as to face each other at a predetermined interval, and when the moving electrode plate moves in the horizontal direction, a charging electrode is placed on the large number of detection electrodes. Since a periodic voltage signal for position detection generated by is output, fine position detection becomes possible.

[0009]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of a fine position detecting sensor according to a position embodiment of the present invention.

In the embodiment shown in FIG. 1, an electret is formed by a large number of surface charges 4a, b, c, d ... Charged in the Y direction with respect to the X (horizontal) direction at a molecular level pitch P1 of 1 μm or less. 1 and the surface charge 4 of the electret 1
A large number of metal comb teeth 5e, f, which are arranged at a pitch P1 and a pitch P2 in the same row at positions facing a, b, c, d ...
It is composed of a comb-shaped electrode 2 having g, h ..., and a detection resistor R3 for detecting the average potential of the charge generated in the comb-shaped electrode 2 by the charge of the electret 1, and the electret 1 and the comb. The tooth-shaped electrodes 2 are arranged in a capacitor shape facing each other at a predetermined interval in the X direction.

Next, the operation will be described.

The electret 1 is made of a polymer material PVD.
Using F (polyvinylidene fluoride), FEP (tetrafluoroethylene hexafluoropropylene copolymer), PTFE (tetrafluoroethylene), etc. as a material, an electric field is applied to these materials at high temperature, and the material is cooled to room temperature as it is. It is created by charging using a thermo method, a corona method of applying an electric field to the material at room temperature to cause a corona discharge, or an electron beam method of irradiating the material with an electron beam in a vacuum. In the case of the beam method, fine-pitch charge lines can be drawn on the material by scanning. In this way, once charged, the electrostatic force is maintained even if the electric field is removed.

The material of the comb-teeth-shaped electrode 2 facing the electret 1 at a predetermined interval may be a metal body capable of picking up the electrostatic field of the electret 1, and the predetermined interval to be held is the electrostatic force of the electret 1 to be charged. , It is arbitrarily determined by the required detection level from the comb-teeth-shaped electrode 2.

Now, the electret 1 and the comb-shaped electrode 2
If there is relative movement in the X direction between the pitches (P1, P1,
(Equivalent to P2) Charge and discharge due to induction of surface charge of the electret 1 on the comb teeth 5e, f, g, h ...
Since the error is repeated, the fine position detection data at the molecular level can be obtained by detecting the voltage change across the resistor R3. By processing this detection data with a normal configuration such as FV conversion, direction discrimination, and signal interpolation, a high resolution speedometer at the molecular level, an encoder, etc. can be constructed.

In this case, the moving body may be either the electret 1 or the comb-shaped electrode 2.

Further, although the electret 1 is shown in a linear system in FIG. 1, if a disc type electret 10 is used as shown in FIG. -It is obvious that it can be transferred to the tally system.

In this embodiment, as compared with the conventional optical type and magnetic type, the displacement amount can be directly detected as the electric amount, so that the signal processing is remarkably simplified. If the electron beam method is used for the charge of the electret 1, the charge pitch can be finely cut down to the molecular level, so that a high-resolution system at the molecular level can be constructed. Higher resolution can be achieved by directional discrimination, multiplication, etc. by ordinary signal processing similar to the optical type and magnetic type. Since the sensor that consumes almost no power is used, it is possible to configure a low power consumption fine position control device that is effective when there is no space for accommodating the power supply device or when there is a weight limit.

FIG. 3 is a block diagram of a fine position detecting sensor according to the second embodiment of the present invention.

In the second embodiment, as shown in FIG. 3, a SiO ₂ layer 44 is deposited on a silicon wafer 43 by a CVD method, a ladder-shaped mask is placed on the SiO ₂ layer 44, and a metal film 45 such as aluminum is vapor-deposited on the electrode. After the separation band, the SiO ₂ layer 44
The remaining exposed portion of the electrode is charged by a method such as corona discharge to charge electrode 4 with fine pitch P of 1 μm or less.
6 is formed to form the fixed electrode plate 41.

On the other hand, an electrically insulating plate such as a glass plate 4
A moving electrode plate 42 is formed by vapor-depositing the detection electrodes 48 having the same pitch P as the charge electrodes 46 of the fixed electrode 1 on the movable electrode plate 7, and the charge electrode 46 and the detection electrodes 48 are kept at a predetermined distance from the fixed electrode plate 41. The capacitors are placed on top of each other so that they face each other.

Now, when the movable electrode plate 42 moves in the direction of the arrow, the charge of the fixed electrode plate 41 is changed to the same as in the previous embodiment.
A periodic voltage signal is generated by the di-electrode 46 due to the potential change induced in the detection electrode 48 of the moving electrode plate 42.
This voltage data and frequency data are read, and a fine level high resolution speedometer, encoder, etc. can be constructed as in the previous embodiment.

[0023]

As described above, according to the present invention,
The electret, which has been charged with charge at minute intervals, is made to face the comb-shaped electrode provided with the comb teeth for induction corresponding to the charge, and the charge / discharge generated by induction during relative movement is detected as the potential for position detection. A fixed electrode plate that is configured to convert and output the change, or has a charging electrode with a fine interval formed on the surface of the SiO ₂ layer on the silicon wafer, and the charging electrode on the electrical insulator plate has the same interval at a position facing the charging electrode. Since the moving electrode plates on which the detection electrodes are formed are opposed to each other and a periodic voltage signal for position detection that is induced to the detection electrodes is output during movement, a high-resolution speedometer with a fine level of 1 μm or less, an encoder It becomes possible to configure the da etc. Signal processing is significantly simplified. A low power consumption speedometer, encoder, etc. can be configured.

[Brief description of drawings]

FIG. 1 is a fine position detection sensor according to an embodiment of the present invention.
FIG.

FIG. 2 is an explanatory view of a disc type electret of the present invention.

FIG. 3 is a configuration diagram of a fine position detection sensor according to a second embodiment of the present invention.

FIG. 4 is a perspective view of a conventional linear gauge sensor.

[Explanation of symbols]

1 Electret 2 Comb Toothed Electrode 3 Detection Resistor R 4 Surface Charge 5 Comb Tooth 10 Disc Electret 41 Fixed Electrode Plate 42 Moving Electrode Plate 43 Silicon Wafer 44 SiO ₂ 45 Metal Film 46 Charging Electrode 47 Glass Plate 48 Detection Electrode

Claims (2)

[Claims] 1. A position detecting sensor used for a speedometer, an encoder, etc., comprising: an electret having a large number of surface charges charged at minute intervals, and the electret facing the electret at a predetermined interval. A fine feature characterized by comprising a comb-shaped electrode for converting and outputting charging / discharging repeatedly generated on a large number of comb teeth provided at positions opposed to the surface charges during relative movement in the horizontal direction into potential changes for position detection. Position detection sensor. 2. A position detecting sensor used for a speedometer, an encoder, etc., wherein a fine interval is provided between exposed portions of the SiO ₂ layer separated by a metal film deposition portion on the surface of the SiO ₂ layer deposited on a silicon wafer. Fixed electrode plate on which a large number of charging electrodes are formed, and a large number of detection electrodes having the same interval as the charging electrode at a position facing the charging electrode on an electrical insulator plate facing the fixed electrode plate at a predetermined interval. A fine position detecting sensor, comprising: a moving electrode plate for vapor-depositing and outputting a periodic voltage signal for position detection generated on the detecting electrode when moving in the horizontal direction.