JP3389538B2 - Capacitive sensor - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a capacitance type sensor. More specifically, the present invention relates to a capacitive sensor that combines a high-resolution, short-wavelength position detection signal and a low-resolution, long-wavelength position detection signal to obtain a high-resolution, long-wavelength position detection signal.

[0002]

2. Description of the Related Art In a conventional capacitance type sensor, in order to achieve high precision and high resolution, it is necessary to narrow the electrode pattern pitch of the scale and grid. As a method for realizing this, at present, an electrode pattern is formed by a thin film on a glass substrate and configured.

[0003]

However, in order to form an electrode pattern with a thin film on a glass substrate, an expensive film forming apparatus is required, so that there is a problem that the cost becomes high. Further, in order to increase the accuracy and resolution of a wide area, it is necessary to increase the number of tracks. However, if this is done, it is indispensable to increase the area, and there is a problem that the price is further increased.

An object of the present invention is to solve the above-mentioned problems of the related art and to provide a capacitance type sensor capable of achieving high precision and high resolution in a wide range without increasing the cost.

The capacitance type sensor of the present invention adopts the following constitution in order to achieve the above object. In the capacitance type sensor according to claim 1, a first capacitance type electrode having a high resolution and a short wavelength and a second capacitance type electrode having a low resolution and a long wavelength are formed in a position detection direction. A first capacitance type electrode that has a scale and electrodes that face the first capacitance type electrode via a constant gap, and that generates a high-resolution short-wavelength position detection signal by these opposing electrodes. A second capacitance having a detection means and an electrode facing the second capacitance type electrode with a constant gap interposed therebetween, and generating a position detection signal of low wavelength with low resolution by these facing electrodes. An electrostatic detector for synthesizing the high-resolution short-wavelength position detection signal and the low-resolution long-wavelength position detection signal to obtain a high-resolution long-wavelength position detection signal. A capacitance type sensor, wherein the first capacitance type detection means is provided. The electrode is formed by thin film molding on a first substrate made of a material having a small thermal expansion coefficient, and the electrode of the second capacitance type detection means is made of a material having a larger thermal expansion coefficient than that of the first substrate. It is characterized in that it is formed on the second substrate by printing.

Here, the material having a small coefficient of thermal expansion forming the first substrate means glass, ceramics, glass ceramics, quartz (crystal), or the like. The material having a larger thermal expansion coefficient than that of the first substrate forming the second substrate means epoxy resin, polyester, aramid, polyimide, or the like.

According to this structure, the second capacitance type detection means is opposed to the second capacitance type electrode via a constant gap and generates a long wavelength position detection signal with low resolution. Since the electrodes are formed by printing on the second substrate made of a material such as epoxy resin, these electrodes can be formed without using an expensive film forming apparatus. At this time, the first capacitance type electrode is opposed to the first capacitance type electrode via a certain gap and generates a high resolution short wavelength position detection signal.
The electrodes of the capacitance type detection means are formed by thin film molding on the first substrate made of a material such as glass, that is, for the electrode having a small alignment tolerance, the first substrate made of a material such as glass. Since the electrodes having large alignment tolerance are formed by printing on the second substrate made of a material such as epoxy resin by the thin film molding, the electrodes of each detecting means can be made of a material according to the required accuracy. In other words, cost can be reduced while maintaining accuracy. In addition, since the high-resolution short-wavelength position detection signal and the low-resolution long-wavelength position detection signal are combined to obtain the high-resolution long-wavelength position detection signal, it is possible to obtain high precision and high resolution over a wide range. Can be converted. Therefore, high precision and high resolution can be achieved over a wide range without increasing the cost.

According to a second aspect of the present invention, there is provided the capacitance type sensor according to the first aspect, wherein the electrodes of the second capacitance type detection means are printed on an epoxy resin substrate. It is characterized by being formed. According to such a configuration, the electrodes forming the second electrostatic capacitance type detection means are formed on the epoxy resin substrate by printing, so that the electrodes can be formed easily and inexpensively.

According to a third aspect of the present invention, in the capacitance type sensor according to the first aspect, the electrode of the first capacitance type detecting means has a thin metal film on a glass substrate. It is characterized by being formed by molding. According to this structure, since the electrodes forming the first capacitance type detecting means are formed by forming a thin metal film on the glass substrate, the high precision required for achieving high resolution is achieved. You can guarantee the perfect processing.

The capacitance type sensor according to a fourth aspect is the capacitance type sensor according to the first aspect, wherein the electrode of the first capacitance type detecting means is a thin metal film on a ceramic substrate. It is characterized by being formed by molding. According to such a structure, in the case of a ceramic substrate,
Holes are easier to drill than glass substrates, and laser drilling is possible. Therefore, if holes are made in the ceramic substrate and copper or the like is poured into the holes so that electric signals are guided from the electrodes on the front surface to the rear surface, wiring is easy and a circuit such as a preamplifier can be formed on the rear surface. Therefore, the device can be made more compact.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view of the capacitance type sensor of the present embodiment, and FIG. 2 is a view seen from the direction II in FIG.
As shown in these figures, the electrostatic capacitance sensor of the present embodiment includes a scale 1 made of a glass substrate and a slider 21 provided so as to be capable of reciprocating in the longitudinal direction of the scale 1.
With.

The scale 1 has a first resolution of high resolution and a short wavelength.
The first track 11 having the electrostatic capacitance type electrode and the second track 12 having the second capacitance type electrode having low resolution and long wavelength are parallel to each other and in the position detection direction (of the scale 1). It is formed along the longitudinal direction). The first track 11 is provided with a plurality of reception electrodes 11A formed at a predetermined pitch along the longitudinal direction of the scale 1 and a plurality of transmission electrodes 11B and 11C connected to each reception electrode 11A. There is. The second track 12 has a predetermined pitch (the receiving electrode 11) along the longitudinal direction of the scale 1.
A plurality of receiving electrodes 12 formed with a pitch larger than A)
A and a plurality of transmission electrodes 1 connected to each reception electrode 12A
2B and 12C are provided respectively.

The slider 21 is provided with a metallic slider substrate 22 movably provided in the longitudinal direction of the scale 1 via a holder (not shown). The slider substrate 22 is
It has a rectangular peripheral frame 22A and a holding portion 22B that is connected to one inner edge of the peripheral frame 22A and is separated from the remaining three inner edges. In other words, with respect to the peripheral frame 22, the holding portion 22B uses the one inner edge as a fulcrum.
2 is provided so as to be displaceable in the thickness direction. Holding part 22
A glass substrate 23 as a first substrate made of a material having a small thermal expansion coefficient is attached to the upper side of the center of B, and an epoxy resin as a second substrate is provided on substantially the entire surface of the holding portion 22B except the glass substrate 23. A substrate, here a glass epoxy substrate 24, is attached. That is,
A glass epoxy substrate 24 made of a material having a larger thermal expansion coefficient than the first substrate is attached to substantially the entire surface of the holding portion 22B except the glass substrate 23.

The first track 11 is provided on the glass substrate 23.
A group of eight transmitting electrodes 31A capacitively coupled to the receiving electrodes 11A of the first transmitting electrodes 11B and the transmitting electrodes 11B, 1 of the first track 11
The detection electrodes 31B, 31 facing the 1C and capacitively coupled
C and C are formed respectively. These electrodes 31A,
31B and 31C are first electrostatics that generate a high-resolution short-wavelength position detection signal due to the relationship with the first capacitive electrodes (11A, 11B, 11C) facing each other with a constant gap. It constitutes a capacitance type detection means, and is formed by, for example, forming a metal thin film using a film forming apparatus.

On the glass epoxy substrate 24, a group of eight transmitting electrodes 32A capacitively coupled to the receiving electrodes 12A of the second track 12 and the transmitting electrodes 1 of the second track 12 are provided.
A detection electrode 32 facing the 2B and 12C and capacitively coupled
B and B are formed respectively. These electrodes 32A,
32B is a second capacitance type that generates a low-resolution long-wavelength position detection signal due to the relationship with the second capacitance type electrodes (12A, 12B, 12C) facing each other with a certain gap. It constitutes a detection means, and is formed by printing on the glass epoxy substrate 24, for example.

Around the electrodes 31A, 31B, 31C constituting the first capacitance type detection means, specifically, the electrode 31
These electrodes 31A, 31B, 31C and the scale 1 are placed at the respective vertex positions of the triangle containing A, 31B, 31C.
Gap holding means 51A to 51C for holding a constant gap with respect to the electrode surface are provided. A gap between the electrodes 32A and 32B and the electrode surface of the scale 1 is provided around the electrodes 32A and 32B constituting the second capacitance type detection means, specifically, on the upper and lower positions on both sides of the electrodes 32A and 32B. Gap holding means 52A to 52D for holding the above are respectively provided. These gap holding means 5
Each of 1A to 51C and 52A to 52D has a spherical ball at its tip, and the ball slides while being in contact with the surface of the scale 1.

In such an electrostatic capacitance type sensor, a group of transmitting electrodes 31 constituting the first electrostatic capacitance type detecting means.
When an 8-phase periodic signal whose phase is shifted by 45 degrees is supplied to A as a drive signal, a signal corresponding to the displacement of the slider 21 with respect to the scale 1 (a high-resolution short-wavelength position detection signal) is supplied from the detection electrodes 31B and 31C. ) Is obtained. In addition, a group of transmitting electrodes 32 constituting the second capacitance type detecting means.
When an 8-phase periodic signal whose phase is shifted by 45 degrees is supplied to A as a drive signal, the scale 1 is fed from the detection electrode 32B.
A signal (a low-resolution long-wavelength position detection signal) corresponding to the displacement of the slider 21 with respect to is obtained. Then, the high-resolution, short-wavelength position detection signal obtained by the first capacitance type detection means and the low-resolution, long-wavelength position detection signal obtained by the second capacitance type detection means are combined. By doing so, it is possible to obtain a high-resolution, long-wavelength position detection signal.

Therefore, according to this embodiment, the first capacitance type electrodes 11A to 11C of high resolution and short wavelength and the second capacitance type electrodes 12A to 12C of low resolution and long wavelength.
With a scale 1 formed in the position detection direction, and an electrode 3 facing the first electrostatic capacitance type electrodes 11A to 11C via a constant gap and generating a high-resolution short-wavelength position detection signal.
1A to 31C and second capacitance type electrodes 12A to 12C
And electrodes 32A and 32B facing each other through a certain gap and generating a low-resolution long-wavelength position detection signal, a high-resolution short-wavelength position detection signal and a low-resolution long-wavelength position detection signal. In a capacitance type sensor that obtains a high-resolution long-wavelength position detection signal, it is opposed to the second capacitance-type electrodes 12A to 12C via a constant gap and has a low resolution and a long-wavelength position. Electrode 3 for generating detection signal
Since 2A and 32B are formed by printing on the glass epoxy substrate 24, these electrodes 32A and 32B can be formed without using an expensive film forming apparatus.

Further, the first capacitance type electrodes 11A-11
Electrodes 31A to 31C that face C with a constant gap and generate a position detection signal of high resolution and a short wavelength are formed on the glass substrate 23 by thin film molding, that is, electrodes with a small alignment tolerance. 31A to 31C
Is formed by thin film forming on the glass substrate 23, and the electrodes 32A and 32B having a large alignment tolerance are formed by printing on the glass epoxy substrate 24. Therefore, the electrodes of each detecting means are made of a material according to the required accuracy. it can. In other words, cost can be reduced while maintaining accuracy. In addition, since the high-resolution short-wavelength position detection signal and the low-resolution long-wavelength position detection signal are combined to obtain the high-resolution long-wavelength position detection signal, it is possible to obtain high precision and high resolution over a wide range. Can be converted. Therefore, high precision and high resolution can be achieved over a wide range without increasing the cost.

In particular, since the electrodes 32A and 32B constituting the second capacitance type detecting means are formed on the glass epoxy substrate 24 by printing, they can be formed easily and inexpensively. Further, since the electrodes 31A to 31C forming the first electrostatic capacitance type detection means are formed by thin metal film molding on the glass substrate 23, high-precision processing necessary for achieving high resolution. Can be guaranteed.

Further, the gap holding means 51A is provided around the electrodes 31A, 31B, 31C constituting the first electrostatic capacitance type detection means, specifically, at each vertex position of a triangle including the electrodes 31A, 31B, 31C. 51C are provided, the gap between these electrodes 31A, 31B, 31C and the electrode surface of the scale 1 can be kept constant. Also,
Electrodes 32A, 32 constituting second capacitance type detection means
Since gap holding means 52A to 52D are provided around B and 32C, specifically, on both upper and lower sides of the electrodes 32A and 32B, the gap between these electrodes 32A and 32B and the electrode surface of the scale 1 is made constant. Can be held. Moreover, these gap holding means 51A to 51C, 52
Since each of A to 52D has a spherical ball at its tip, the ball can slide smoothly while being in contact with the surface of the scale 1. That is, the slider 21 can be moved smoothly while ensuring a certain gap.

In the above embodiment, the electrode 32 is opposed to the second capacitance type electrodes 12A to 12C via a constant gap and generates a position detecting signal of long wavelength with low resolution.
Although A and 32B are formed by printing on the glass epoxy substrate 24, the present invention is not limited to this. For example, PCB
It may be formed in the same manner as a (printed circuit board) or an FPC (flexible printed circuit). These materials include polyester, aramid,
There is polyimide or the like, but it may be formed by printing a copper foil electrode on this.

Further, in the above embodiment, the electrode 31A facing the first capacitance type electrodes 11A to 11C via a constant gap and generating a high-resolution short-wavelength position detection signal.
31C are formed on the glass substrate 23, but ceramics, glass ceramics, quartz (crystal) or the like may be used. In particular, ceramic-based materials have the advantage of being easier to perforate than glass. In the case of glass, cracks may occur during the punching process, but with ceramic-based materials, such problems are relatively small. Therefore, for example, if a hole is made by a laser and a conductive material such as copper is poured into the hole to guide an electric signal from the electrode on the front surface to the back surface, wiring becomes easier, and a circuit such as a preamplifier is formed on the back surface. Therefore, the device can be made more compact.

In the above embodiment, the scale 1 is made of a glass substrate. However, for example, the first track 11 having the first capacitive electrodes 11A to 11C of high resolution and short wavelength is made of a glass substrate. The second track 12 having the second capacitive electrodes 12A to 12C of low resolution and long wavelength is made of a glass epoxy substrate, that is,
Alternatively, the scale 1 may be created separately and the scale 1 may be created by pasting these two scales together.

[0025]

According to the capacitance type sensor of the present invention, the second capacitance type electrode is opposed to the second capacitance type electrode through a constant gap and generates a position detecting signal of long wavelength with low resolution. Since the electrodes of the capacitance type detection means are formed by printing on the second substrate such as epoxy resin, these electrodes can be formed without using an expensive film forming apparatus. In addition, it faces the first capacitance type electrode through a certain gap,
Since the electrode of the first capacitance type detection means for generating a high-resolution and short-wavelength position detection signal is formed by thin film molding on the first substrate such as glass, that is, an electrode with a small alignment tolerance. Is formed by thin film molding on a first substrate such as glass, and electrodes with a large alignment tolerance are formed by printing on a second substrate such as epoxy resin. It can be composed of materials. In other words, cost can be reduced while maintaining accuracy. In addition, since the high-resolution short-wavelength position detection signal and the low-resolution long-wavelength position detection signal are combined to obtain the high-resolution long-wavelength position detection signal, it is possible to obtain high precision and high resolution over a wide range. Can be converted.
Therefore, high precision and high resolution can be achieved over a wide range without increasing the cost.

[Brief description of drawings]

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

FIG. 2 is a view seen from a direction II in FIG.

[Explanation of symbols]

1 scale 11A receiving electrode 11B, 11C transmission electrodes 12A receiving electrode 12B, 12C transmission electrodes 21 Slider 23 glass substrate (first substrate) 24 Glass epoxy substrate (second substrate) 31A transmitter electrode 31B detection electrode 32A transmitter electrode 32B detection electrode

Continuation of front page (56) Reference JP-A-6-307802 (JP, A) JP-A-49-66155 (JP, A) JP-A-6-207805 (JP, A) JP-A-56-107120 (JP , A) JP-A-5-264291 (JP, A) JP-B-4-35689 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01B 7/00 G01D 5/245 G01D 5/245 102 G01B 21/00

Claims (4)

(57) [Claims] 1. A scale in which a high-resolution, short-wavelength first capacitive electrode and a low-resolution, long-wavelength second capacitive electrode are formed in a position detection direction, and the first static electrode. A first capacitance type detection means having electrodes facing the capacitance type electrodes via a certain gap, and generating high-resolution short-wavelength position detection signals by these facing electrodes; An electrostatic capacitance type electrode having electrodes facing each other through a certain gap, and a second capacitance type detecting means for generating a low-resolution long-wavelength position detection signal by these opposing electrodes, A capacitive sensor that combines a high-resolution short-wavelength position detection signal and a low-resolution long-wavelength position detection signal to obtain a high-resolution long-wavelength position detection signal, The electrode of the first capacitance type detection means has a coefficient of thermal expansion. It is formed by thin film molding on a first substrate made of a small material, and the electrodes of the second capacitance type detection means are printed on a second substrate made of a material having a thermal expansion coefficient larger than that of the first substrate. An electrostatic capacitance type sensor characterized by being formed. 2. The capacitance type sensor according to claim 1, wherein the electrodes of the second capacitance type detection means are formed by printing on an epoxy resin substrate. Sensor. 3. The capacitance type sensor according to claim 1, wherein the electrode of the first capacitance type detection means is formed by forming a thin metal film on a glass substrate. Capacitive sensor. 4. The capacitance type sensor according to claim 1, wherein the electrode of the first capacitance type detection means is formed by forming a thin metal film on a ceramic substrate. Capacitive sensor.