JPH07111355B2 - Capacitive displacement measuring device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring device for linear or angular displacement measurement, and more particularly, to an improved electrostatic capacitance capable of performing displacement measurement with high accuracy even if it is downsized. The present invention relates to a shape displacement measuring device.

[0002]

BACKGROUND OF THE INVENTION Many capacitive measuring devices have been developed for making linear or angular displacement measurements.

In this capacitance type measuring device, two supporting members on which electrodes are arranged are moved relatively,
The relative position of these two support members is determined by knowing the change in the capacitance pattern caused by the electrodes of interest formed on the respective support members.

Specifically, the relative position is determined by supplying a plurality of periodic signals to one electrode array and measuring the shift of the signal transmitted to the other electrode array arranged opposite to each other. What is known is.

Such a measuring device has a wide range from a large-scale device such as a three-dimensional coordinate measuring system and a numerically controlled finishing machine to a small-scale device such as a portable caliper and a micrometer. Spans.

In the above-mentioned capacitance type displacement measuring device, the transmitting electrode and the receiving electrode are arranged in parallel on one of the supporting members which are movable relative to each other, and the opposite electrodes are respectively electrostatically coupled to these two electrodes on the other side. Displacement between the support members by disposing electrodes, and causing the counter electrode to receive a signal output from the transmitting electrode and causing the receiving electrode to receive a corresponding electric signal and detecting electrostatic information thereof. It is known to measure.

In this capacitance type displacement measuring device, the capacitance between the electrodes (transmitting electrode and counter electrode) of a desired combination is
The measurement principle is that it changes depending on the relative position (displacement) of both support members.

Therefore, it is important to prevent an unnecessary floating capacitance from occurring between electrodes other than the desired combination, and to prevent a decrease in measurement accuracy due to the floating capacitance.

That is, as described above, a transmitting electrode for inputting an electric signal and a receiving electrode for detecting an electrostatic signal in response to the input via the counter electrode are arranged in parallel on one of the same supporting members. In this case, in order to accurately measure the displacement between the other relatively moving supporting member, the transmitting electrode and the receiving electrode on the same supporting member are sufficiently electrostatically insulated, and the transmitting electrode and the receiving electrode are sufficiently insulated. It is important to prevent unnecessary floating capacitance from being generated between the electrodes.

[0010]

However, when the above capacitance type displacement measuring device is applied to the above-mentioned small-scale device, etc., the distance between the transmitting electrode and the receiving electrode formed on the same supporting member is small. Since it is inevitably small, an unnecessary floating capacitance caused by electrostatic induction between these two electrodes easily causes a measurement error.

The smaller the capacitance type displacement measuring device is, the narrower the electrode interval becomes, and the greater the influence of the floating capacitance becomes. As a result, there is a problem that a small capacitance displacement measuring device may not be able to ensure the measurement accuracy.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a capacitance type displacement measuring device having excellent measurement accuracy even in the case of miniaturization.

[0013]

SUMMARY OF THE INVENTION The present invention relates to a capacitance type displacement measuring device in which a transmitting electrode and a receiving electrode are arranged in parallel on one surface of a supporting member which moves relative to each other. interposed between the insulating region, the order to block or attenuate the electrostatic induction between the both electrodes, the insulating territory
Through hole penetrating the supporting member in the area and the through hole
Backside ground formed on the backside of the support member via
The above-mentioned problem is achieved by providing the shield portion including the ground electrode electrically connected to the electrode .

[0014]

[0015]

First, the measuring principle of the capacitance type displacement measuring device will be described with a specific example.

FIG. 4 shows a capacitance type linear measuring caliper 10 which is an example of the capacitance type displacement measuring device.

Regarding such calipers 10, US patent application 07/200368 (corresponding Japanese patent application is Japanese Patent Application No. 1-171378) and US patent application 07/200580 (corresponding Japanese patent application), which are prior applications of the applicant. (Japanese Patent Application No. 1-171379) (U.S. filing date is May 31, 1988).

Briefly, the caliper 10 includes a capacitance converter (TRANSDUCER) 12 and an electronic measuring device (ELECTRONIC MEASURING APP).
ARATUS) 100 and.

The electronic measuring device 100 includes a signal generator (SIGN) for supplying an electrical excitation signal to the converter 12.
AL GENERATOR) 102 and a signal processor (SIGNAL PRO) for processing the output signal generated by the converter 12 to establish a predetermined measurement position.
CESSOR) 104.

The converter 12 includes a linear first support member 20.
And a second support member 30 slidably attached so as to perform axial displacement in the longitudinal direction with respect to the member 20 along a predetermined measurement axis X. The second support member 30 is generally known as a pickoff member.

Each of the support members 20 and 30 is usually equipped with a caliper arm (not shown) used to enable the dimension measurement of an object.

The support members 20 and 30 are respectively
Has a flat surface, on which is described below,
Various electrode arrangements or structures 210, 220 and 310, 3
20 are arranged respectively.

The supporting members 20 and 30 face each other in parallel with a space (for example, 0.05 mm) therebetween.
The second support member 30 is slidably supported with respect to the first support member 20 so as to be displaceable in the vertical direction (X direction) along the measurement axis.

An electrode structure 3 is formed on the second supporting member 30.
10 and 320 are arranged close to each other, aligned with the measuring axis X. Similarly, on the first support member 20, the electrode structures 210 and 220 are arranged in close proximity to each other while being electrically connected, aligned with the measurement axis.

The excitation signal output of the signal generator 102 is
Connected to each electrode 312 of the electrode structure 310, the signal processor 104 receives the output of the converter 12 to receive the output of the electrode structure 3.
Connected to 20. For convenience of explanation, the electrodes of the electrode structure 310 (hereinafter, also referred to as an array 310) are referred to as first electrodes.
An electrode structure 210 (hereinafter referred to as an array 210
(Hereinafter also referred to as “electrode”) is referred to as a first receiving electrode, and an electrode structure 2
The 20 electrodes (hereinafter also referred to as the array 220) are referred to as second transmitting electrodes, and the electrode structure 320 is referred to as a second receiving electrode.

In the illustrated example, the first transmitter electrode 310
Are a plurality of identical shapes, which are arranged so as to form a rectangular envelope having a width Wt and a length Tl extending in the direction of the measurement axis X and which are arranged at regular intervals of a pitch Pt and are evenly spaced from each other. It is formed as a rectangular electrode.

Also, as shown, successive series of one or more predetermined numbers (8 in the figure) of adjacent electrodes 312 are each connected to a corresponding series of different excitation or input signals. , Each series of electrodes constitutes a group of lengths over a distance which determines one transmission wavelength Lt.

The second receiving electrode 320 has a substantially elongated shape having widths Wr and Rl extending in the direction of the measurement axis X and arranged in parallel with the first transmitting electrode 310.

The first receiving electrode array 210 includes a plurality of rectangular electrode elements 212, which are arranged in the direction of the measurement axis X and are arranged close to each other on the first supporting member 20 at a uniform interval. I have it.

Similarly, the second transmitting electrode array 220 also includes a plurality of rectangular electrode elements 222, which are arranged in the measurement axis X and are arranged close to each other with a space therebetween. The individual electrode elements 222 of the second transmitting electrode array 220 are respectively connected to the first receiving electrode array 2
It is electrically coupled to ten corresponding individual electrode elements 212.

The first transmitting electrode 312 and the first receiving electrode 212 are disposed on the supporting members 20 and 30, respectively, and during relative movement of the first and second supporting members 20 and 30 along the measuring axis, It is designed to maintain face-to-face relationships at intervals. Similarly, the detection electrode 320 and the second transmission electrode 222 are also disposed on the support members 30 and 20, respectively, and are in a face-to-face relationship at intervals during movement of the support members 20 and 30 along the measurement axis. It is supposed to be maintained.

As explained in more detail in the related application, a periodically changing excitation signal is applied by the signal generator 102 to each group of the first transmitting electrodes 310. The signal from the first transmitting electrode 312 is capacitively coupled to the first receiving electrode 212 and electrically coupled to the second transmitting electrode 222.

The signal is then transmitted by capacitive coupling to the second receiving electrode 320, which receives the electrode 32.
When the 0 produces an output signal, the output signal is detected by the signal processor 104. The signal processor 104 then provides a position indication by sensing the relationship between the signal transmitted to the first transmission electrode 312 and the signal received at the detection electrode 320.

Further, as another example of the caliper 10, as shown in FIG. 5, the first transmitting electrode 310 'has a shape having tapered portions 316A and 316B at both ends in the measurement axis direction. Other than the above, the one having the same basic structure is the US patent application 07/357, which is a prior application of the applicant.
699 (corresponding Japanese application is Japanese Patent Application No. 2-132434).

In the caliper (capacitive displacement measuring device) 10 described in detail above, the electrodes (first transmitting electrode 310, first receiving electrode 210, second transmitting electrode 22) of a desired combination are formed.
If the electrostatic levitation capacitance is generated between the electrodes other than 0 and the second receiving electrode 320, that is, between the first transmitting electrode 310 (310 ') and the second receiving electrode 320, the measurement accuracy is deteriorated.

Therefore, in the present invention, for example, as shown in FIG. 1 described later, a transmitting electrode 310 ″ (corresponding to the first transmitting electrode) and a receiving electrode 320 ″ (corresponding to the second receiving electrode). By providing a shielding portion composed of a ground electrode and a through hole in the insulating region Z between the electrodes 310 and 310,
The electrostatic induction between ″ and 320 ″ is blocked or attenuated. In this case, the counter electrode (not shown)
Corresponds to the electrodes 210 and 220.

As described above, since it is possible to block or attenuate the electrostatic induction between the electrodes 310 "and 320" where it is desired to electrostatically avoid the interaction, it is possible to reduce the measurement accuracy. The distance between these two electrodes can be reduced, and as a result, it has become possible to obtain a small caliper 10 having excellent measurement accuracy.

[0038]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1A is a partial plan view showing an essential part of the capacitance type caliper which is the first embodiment of the present invention, FIG.
[Fig. 4] is a perspective view of a partially broken portion thereof.

The capacitance type displacement measuring device of this embodiment has a basic structure shown in FIG. 4 or 5, except that the second supporting member 30 has the structure shown in FIG. 1 (A). It is practically the same as the one.

The second support member 30 has tapered portions 316A at both ends in the same measuring direction as that shown in FIG.
And 316B, a transmitting electrode 310 ″ composed of an electrode element 312 ″ and a receiving electrode 320 ″ extending in the measurement axis direction in the vicinity of the transmitting electrode 310 ″ are juxtaposed. The receiving electrode 320 ″ is formed of two receiving electrodes (a) and (b) having complementary shapes. The insulating region Z located between the electrodes 310 ″ and 320 ″ is formed by the insulating substrate 40 forming the support member 30.

In this embodiment, as shown in the enlarged view of FIG. 1B, the transmitting electrode 310 ″ and the receiving electrode 32 are
A ground electrode 42 and a through hole 44 formed in the central portion of the ground electrode 42 at a predetermined pitch in the measurement axis X direction as a shield portion for blocking or attenuating electrostatic induction with 0 ″.
And are provided in the insulating region Z.

The ground electrode 42 is electrically connected to the back surface ground electrode 42A attached to the back surface of the substrate 40 through the through hole 44.

In this embodiment, as described above, the shield portion (ground electrode 42, through hole 44) 46 is provided in the insulating region Z.
Since this is provided, it is possible to effectively prevent generation of unnecessary floating capacitance between the transmitting electrode 310 ″ and the receiving electrode 320 ″.

Therefore, the capacitance type caliper 10 of this embodiment is used.
Can obtain an excellent measurement accuracy even when the distance between the transmission electrode 310 ″ and the reception electrode 320 ″ is small, so that the capacitance type caliper itself can be obtained without lowering the measurement accuracy. It can be miniaturized.

FIG. 2 is a partial cross-sectional view showing an essential part of the second embodiment of the present invention, which corresponds to a view of the fractured part of FIG. 1B as seen from the front.

In this embodiment, an electrode having a V-shaped cross section is provided on the substrate (insulation region) located between the transmitting electrode 310 ″ and the receiving electrode 320 ″, and the ground electrode shown in FIG. The shield portion 46 made of a conductor extending in the same direction as the extending direction of the electrode 42 is provided. The shield 4 shown in FIG.
6 corresponds to the portion of the ground electrode 42, and the illustration is omitted.
However, the through hole 44 is formed as in the first embodiment.
It is electrically connected to the back surface ground electrode 42A via the.

By doing so, both electrodes 3
Since the capacitance between the 10 ″ and the receiving electrode 320 ″ can be reduced, similar to the capacitance type caliper 10 of the first embodiment, it is possible to achieve excellent measurement accuracy even if the size is reduced. You can

FIG. 3 is a partial cross-sectional view corresponding to FIG. 2 showing a main part of a third embodiment of the present invention.

In this embodiment, the shield portion 46 is formed in a convex shape contrary to the case of the second embodiment, and a second shield portion 46A protruding in the same direction as the shield portion 46 is arranged on the back side thereof. It has a set configuration.

In the case of the present embodiment as well, excellent measurement accuracy can be exhibited even if the size is reduced.

Although the present invention has been specifically described above, it is needless to say that the present invention is not limited to the above-mentioned embodiments.

For example, the shielding portion provided in the insulating region between the transmitting electrode and the receiving electrode is a through hole and the through hole.
Backside ground electrode electrically connected to it are the aforementioned ground electrode Te, V-shaped conductor is not limited to those made of a conductor of convex shape, or to prevent the occurrence of floating capacitance between the two electrodes,
It has a shape that can be or attenuate, as possible out be of any shape.

Further, the configurations, shapes, etc. of the transmitting electrodes and the receiving electrodes can be arbitrarily changed as required.

Further, the capacitance type displacement measuring device is not limited to the capacitance type calipers described above, but may be any capacitance type displacement measuring device for measuring displacement such as straight line or rotation. Good.

[0056]

As described above, according to the present invention, excellent measurement accuracy can be exhibited even when the capacitance type displacement measuring device is downsized.

[Brief description of drawings]

FIG. 1 (A) is a partial plan view showing a main part of a first embodiment, and FIG. 1 (B) is an enlarged perspective view of a partially broken part thereof.

FIG. 2 is a partial cross-sectional view showing a main part of the second embodiment.

FIG. 3 is a partial cross-sectional view showing a main part of the third embodiment.

FIG. 4 is a partial perspective view showing an example of a capacitance-type caliper.

FIG. 5 is a partial perspective view showing another example of the capacitance type caliper.

[Explanation of symbols]

 20 ... 1st supporting member, 30 ... 2nd supporting member, 40 ... Substrate, 42 ... Ground electrode, 44 ... Through hole, 46 ... Shielding part, 310 '' ... Transmitting electrode, 320 '' ... Receiving electrode, Z ... Insulation region.

Claims (1)

[Claims] 1. A capacitance type displacement measuring device in which a transmitting electrode and a receiving electrode are arranged in parallel on one surface of a supporting member which moves relatively, and an insulating region interposed between the transmitting electrode and the receiving electrode. in, the order to block or attenuate the electrostatic induction between the both electrodes, the upper
A through hole penetrating the supporting member in the insulating region,
Formed on the back surface of the support member through the through hole
From the back side ground electrode and the ground electrode electrically connected
A capacitance type displacement measuring device, characterized in that a shield portion is provided.