JPS61271411A - Electro-static capacity type encoder - Google Patents

Abstract

PURPOSE:To attempt the improvement of measuring accuracy and minituarization of an encoder, by separated construction of double-series electric transmitting electrodes on individual fixing plates. CONSTITUTION:A rotating table 10 set free to rotate on the main body, No.1 and No.2 fixed plates 30, 32 fixed on the main body facing one against the other through this are installed. On the fixed plate 30(32), the No.1(No.2) electrode 14A(14B) arranged annulally with equi-distance along the periphery with unit electrode plates applied with AC voltages of different phase (with a difference of phase by 180 deg. from the unit electrode plate of the transmitting electrode 14A) are installed and on the inside periphery, the No.1(No.2) output electrode 22A(22B) is installed. Further,, on the rotating plate 10, the No.1(2) receiving electrode 18A(18B) facing to each other mounted over the electrode 14A(14B) and electrode 22A(22B) is installed. These electrodes are so made that they commonly face the specified unit electrode plate applied with a common-phase AC voltage. And, by the rotation of the rotating plate 10, a rotating displacement is detected by output signals issued from the electrode 22A(22B).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a capacitive encoder, particularly an electrostatic foot encoder that electrically detects the amount of rotational displacement of a rotating plate.

[Prior Art] Various measuring devices using encoders are conventionally known, and these measuring devices include a probe that moves on the main body of the device and contacts an object to be measured, and the amount of movement of the probe is measured using an encoder. The value is digitally displayed on the display.

By the way, capacitive encoders have been well known as encoders used in this type of measuring equipment, and today there are efforts to improve the portability and interchangeability of such capacitive encoders. There are demands from above to make them smaller and lighter.

11 Blood 1 Tan 1" FIG. 4 and FIG. 5 show such a conventional capacitive encoder, and this encoder has a main body that is rotated by a rotating shaft 10a that rotates according to the amount of movement of the probe. A device that detects the amount of rotational displacement of the rotating plate 10 with respect to the fixed plate 12, including a rotating plate 10 rotatably attached to the rotating plate 10 and a fixed plate 12 attached to the main body so as to face the rotating plate 10. It is.

Therefore, on the surface of the fixed plate 12, a plurality of unit electrode plates 14a are arranged in a ring shape at equal intervals along the circumferential direction to form a transmitting type ff114. To each of these unit electrode plates 14a, a voltage application circuit 16 applies a sine wave or rectangular wave alternating current voltage with a predetermined phase, in the embodiment, the phase is shifted by 45 degrees, and 8 sets of unit electrode plates 14a are applied.
A plurality of sets of electrode units 100 are formed, each unit being 1 unit.

Further, the same number of receiving electrodes 18 as the number of electrode units are provided on the surface of the rotary plate 10, and each receiving electrode 18 is formed to face a predetermined number of continuous unit electrode plates 14a included in each electrode unit 100. has been done.

In the encoder shown in FIG.
and 45 degrees with respect to this reference voltage v1.

90', 135'' f phase to ftl = V2.
V3. Four unit electrode plates 14 to which each voltage of V4 is applied
They are arranged facing each other across a.

Furthermore, a ground electrode 20 is provided on the surface of the rotating plate 10 and is located between each of the receiving electrodes 18.
This prevents the negative effects of capacitance interference from other sources.

With the above configuration, when the rotating plate 1o is rotated, the transmitting electrode 14 and the receiving electrode 18 move relative to each other, and the receiving electrode 18 receives the amount of rotational displacement of the rotating plate 10, as is well known. An electrostatic signal V with a corresponding periodic variation.

is detected.

In this way, the voltage ■ obtained at the receiving electrode 18 on the rotary plate 10. In order to take out the output to the main body side, a ring-shaped output 1 is provided on the surface of the fixed plate 12 located inside the transmitting electrode 14.
&22, and the receiving electrode 18 is formed so as to straddle and face both the transmitting electrode 14 and the output electrode 22 provided on the fixed plate 12.

With the above configuration, according to this encoder, the capacitance mother signal o obtained at the receiving electrode 18 can be electrostatically coupled without using mechanical contact between the rotary plate 10 and the fixed plate 12. It is possible to accurately measure the rotational displacement of the rotating plate 10 by outputting it to the main body side through the sensor.

However, this conventional capacitive encoder only has one transmitting electrode 14 and an output electrode 22 formed in a substantially ring shape on one fixed plate 12, and therefore has good measurement accuracy. However, if the detection resolution is to be maintained, the fixed plate 12 cannot be made smaller, and this fruiting device cannot be made smaller in the width direction of the fixed plate 12.

That is, in this way, the transmitting electrode 1 is placed on one fixed plate 12.
4 and output electrode 22 are provided, both of these electrodes 1
4.22, adverse effects due to capacitance interference are likely to occur. In order to eliminate this problem, the fixing plate 12
In the above, it is necessary to set a large distance between the transmitting electrode 14 and the output electrode 22, and to provide a ring-shaped ground electrode 24 between the two electrodes 14,22. As a result,
In such a conventional encoder, it is unavoidable that the fixed plate 12 has a large shape and the surface electrode structure is complicated.As a result, the fixed plate 12 becomes large, making it difficult to downsize the entire device in the direction of the rotation radius. The problem was that it was not possible to do so.

Second Background Art In order to eliminate the influence of such electrostatic capacitance interference and to reduce the size of the encoder in the rotation radius direction,
An application for Japanese Patent Application No. 59-228785 was filed on October 29, 1999.

6 and 7 show an electrostatic capacitive encoder according to this application, and members corresponding to those in the first background art are designated by the same reference numerals and their explanations will be omitted.

This encoder includes a rotating plate 10 that is rotatably provided on the main body by a rotating shaft 10a, and a first fixed plate 3 that is fixed to the main body so as to face each other with the rotating plate 10 interposed therebetween.
0 and a second fixing plate 32.

FIG. 7 shows the first fixing plate 30. The respective surface structures of the rotating plate 10 and the second fixed plate 32 are shown, and in the figure, the surface of the rotating plate 10 is a surface facing the first fixed plate 30 and a surface facing the second fixed plate 32. It is shown broken down into two parts.

A transmitting electrode 14 and a receiving electrode 1 are provided on each surface of the first fixed plate 12 and the rotating plate 10, as in the first background art.
8 and a ground electrode 20 are formed, respectively.

Voltage ■ obtained at the receiving electrode 18 formed on the rotary plate 10. A coupling electrode 34 is provided on the opposite surface of the second fixed plate 32 of the rotary plate 10 in order to take out the signal to the main body side, and the coupling electrode 34 is electrically connected to each receiving electrode 18 .

Here, the coupling electrode 34 is formed in a ring shape on the surface of the rotating plate 10 along the circumferential direction.

The coupling electrode 3 is provided on the surface of the second fixing plate 32.
An output electrode 22 formed in a ring shape is provided so as to face the output electrode 7j, and an electrostatic signal V is induced at the receiving electrode 18 by the electrostatic coupling between the output electrode 7j and the coupling electrode 34. is output from the output electrode 22.

The signal ■o output from this output electrode 22,
By comparing it with the reference voltage (1) set in the detection circuit 36, the amount of rotational displacement of the rotating plate 10 can be detected based on the phase difference φ.

As described above, according to the encoder, the transmitting electrode 14, the receiving electrode 18 . The coupling electrode 34 and the output electrode 22 are respectively connected to the first fixing plate 30. Each electrode is provided on each surface of the rotating plate 10 and the second fixed plate 32. Therefore, each electrode provided on the surface of each of these fixed plates 30, 32 and the rotating plate 10 is different from other types of electrodes. From this aspect, each electrode 14, 18, 34 and 22
can be miniaturized without compromising detection accuracy.

In particular, this encoder has the same detection accuracy as the first prior art because there is no need to consider interference due to capacitance between the transmitting electrode 14 and the output electrode 22 as in the first prior art. Then, the radius of the transmitting electrode 14 can be significantly reduced, and as a result, it becomes possible to downsize the encoder in the direction of the rotation radius.

J3, compared to the first background art, this encoder is thicker in the direction of the rotating shaft 10a due to the provision of the second fixed plate 32; Since the interval between the second fixing plates 30 and 32 is extremely small, specifically about 1/10 mm, the increase in thickness in the axial direction caused by providing the second fixing plates 32 in this way is almost ignored. can do.

[Problems to be solved by the invention] By the way, in such a capacitive encoder,
In order to improve the detection resolution, it is necessary to increase the number of unit electrode plates 14a while maintaining the area and spacing of each unit electrode plate 14a constituting the transmitting electrode 14 at appropriate values.

Therefore, in a conventional encoder having a transmitting electrode 14 formed by annularly arranging unit electrode plates 14a, if the detection resolution is to be increased, the radius of the transmitting electrode 14 will inevitably increase, and The drawback is that it is not possible to simultaneously meet the two demands of miniaturization and improvement of detection resolution.

In addition, in a capacitive encoder, it is difficult to form the rotary plate 10 and the first and second fixed plates 30, 32 without causing eccentricity, runout, inclination, etc., and these act as error factors and cause measurement errors. There was a problem that it caused errors.

Purpose of the Invention The present invention has been made in view of such conventional problems, and its purpose is to provide a capacitive encoder that has high measurement accuracy and can be downsized in the direction of the rotation radius. It is about providing.

[Means for Solving the Problems] In order to achieve the above object, the electrostatic 8-tone encoder of the present invention has a rotary plate rotatably provided on the main body, and a rotary plate that faces each other via the rotary plate. The device includes a first fixing plate and a second fixing plate fixed to the main body.

The first fixed plate includes a first transmitting electrode formed by arranging a plurality of unit electrode plates arranged in a ring at equal intervals along the circumferential direction to which alternating current voltages having different phases are applied, and the first transmitting electrode. A first output electrode is provided on the inner peripheral side of the electrode with a shield ring interposed therebetween.

Further, the second fixed plate has a plurality of unit electrode plates to which AC electrodes having a phase different by 180 degrees from each unit electrode plate of the first transmitting electrode are applied in a ring shape at equal intervals along the circumferential direction. a second transmitting electrode arranged in an array; a second output electrode disposed on the inner peripheral side of the transmitting electrode via a shield ring;
will be provided.

The rotary plate also includes a first receiving electrode facing across and facing the first transmitting electrode and the first output electrode, and a first receiving electrode facing across and facing the second transmitting electrode and the second output electrode. 2 receiving electrodes are provided.

The first receiving electrode and the second receiving electrode are both formed to face a predetermined unit electrode plate to which a common phase AC voltage is applied.

[Function] As described above, according to the present invention, two series of transmitting electrodes, the first transmitting electrode and the second transmitting electrode, are provided as the transmitting electrodes that determine the detection accuracy, and these are connected to the first fixed plate and the second transmitting electrode. Because they are formed separately on the second fixed plate, compared to conventional encoders with only one series of transmitting electrodes, the rotational displacement of the rotary plate can be adjusted with approximately twice the accuracy if the size of the transmitting electrodes is the same in the radial direction. If the amount can be detected and the accuracy is the same as that of a conventional encoder, the number of unit electrode plates constituting each transmitting electrode will be approximately 172, and as a result, the encoder can be significantly miniaturized in the radial direction. becomes possible.

Note that since the encoder of the present invention is provided with a second fixed plate compared to the first prior art, it is unavoidable that the encoder becomes thicker by this amount in the direction of the rotation axis.
The spacing between the fixed plates is generally extremely small, specifically 1
/10mm in many cases, so the second
The increase in thickness in the axial direction caused by the provision of the fixed plate can be almost ignored.

Further, according to the present invention, AC voltages having a phase difference of 180 degrees are applied to the first transmitting electrode and the second transmitting electrode, and the first receiving electrode is applied to the first transmitting electrode and the second transmitting electrode. and the second receiving electrode receive voltage signals of the same phase through capacitive coupling.

Therefore, even if there are error factors such as eccentricity, runout, or inclination between the first fixed plate, second fixed plate, and rotating plate,
Measurement errors caused by such error factors are canceled out by taking out the outputs of the first and second receiving electrodes from the first and second output electrodes and combining the output signals, and the error is eliminated. Accurate measurements can be performed regardless of the presence or absence of factors.

[Example] Next, a preferred example of the present invention will be described based on the drawings. Incidentally, members corresponding to those of the conventional apparatus shown in FIGS. 4 and 5 are given the same reference numerals, and their explanations will be omitted.

1 and 2 show a preferred embodiment of the capacitive encoder according to the present invention. and a first fixing plate 30 and a second fixing plate 32 fixed to the main body so as to face each other with the rotary plate 10 in between.

The characteristic feature of the present invention is that the rotary plate 10. By improving the electrode structure provided on the surfaces of the first and second fixed plates 30, 32, the capacitive encoder is made smaller and its detection accuracy is improved.

FIG. 2 shows the surface structures of the first fixed plate 309 rotating plate 1o and the second fixed plate 32, and in the figure, the surface of the rotating plate 10 is connected to the first fixed plate 30. The figure is shown disassembled into a facing surface and a facing surface to the second fixing plate 32.

In the present invention, the first transmitting electrode 14A is provided on the surface of the first fixing plate 30, and is formed by arranging a plurality of unit electrode plates 14a in a ring shape at equal intervals along the circumferential direction.

Further, on the surface of the second fixed plate 32, a second transmitting electrode 14B is provided, which is formed by arranging the same number of unit electrode plates 14b as the first transmitting electrode 14A in a ring shape at equal intervals.

In the embodiment, the first transmitting electrode 14A and the second transmitting electrode 14B are both composed of 16 unit electrode plates 14a and 14b, and these unit electrode plates 14a and 14b are connected to each other via the rotary plate 10. The mountings are fixed on each of the fixing plates 30 and 32 so as to face each other one-to-one.

Then, to each unit electrode plate 14a of the first transmitter 1w114, a voltage application circuit 16 applies a sine wave or rectangular wave alternating voltage with a predetermined phase, in the example, the phase is shifted by 45 degrees, Two sets of electrode units each having an 8 m electrode plate extending from 0 to 315 degrees are formed.

Moreover, each unit electrode plate 14 of the second transmitting electrode 14.8
b, each unit electrode plate 14 is connected by the voltage application circuit 16.
An alternating current voltage consisting of a sine wave or a rectangular wave with a phase shift of 180° relative to a is applied, and in the same way, from 0 to 315°
Two sets of electrode units are formed, with each eight-layer electrode plate as one unit.

That is, as shown in FIG. 2, the first transmitting electrode 14A
An alternating current voltage is applied to the unit electrode plate 14A located on the center line A and sequentially phased at 0.45", 90°, etc., and on the other hand, to the second transmitting electrode 14B, the Starting from the unit electrode plate 14b located on the center line B, which is shifted in phase by 180 degrees in electrical angle with respect to the center line A, AC voltages are applied with the phase shifted sequentially by 0.45 degrees, 90 degrees, and so on. will be done.

Further, two navy blue first receiving electrodes 18A, 18A are provided on the first fixed plate side surface of the rotary plate 10, the same number as the number of electrode units of the first transmitting electrode 14A. The receiving electrodes 14!18A, 18A are arranged point-symmetrically across the center of rotation, and respectively face two sets of four continuous unit electrode plates 14a included in the first transmitting electrode 14A.

Further, on the surface of the rotary plate 10 on the second fixed plate side, there are provided second receiving electrodes 188.18B made of two silks, the same number as the number of electrode units of the second transmitting electrodes 14B. The receiving electrodes 18B, 18B are arranged symmetrically with respect to the center of rotation, and respectively face two sets of four continuous unit electrode plates 14b included in the second transmitting electrode '14.8.

Here, since the first and second receiving electrodes 18A and 18B are capable of receiving signals of the same phase,
They are provided at positions mechanically 90° out of phase with respect to the center of rotation. By doing this, for example, the first receiving electrode 18A can be connected to the first transmitting electrode 14A from 0 to
Similarly, when facing the four unit electrode pairs 14a to which an AC voltage in the range of 135° is applied, the second receiving electrode 18B is in the range of θ to 135° of the second transmitting electrode 14B. The re-receiving electrode 1 faces the four unit electrode plates 14B of
Signals of the same phase can be output from 8A and 18B.

Furthermore, the first transmitting electrode 18A of this rotating plate 14.

A first earth electrode 20Δ, 20A is provided between the rotating plate 18A, and a second earth electrode 20A is provided between the rotary plate 14 and
A second earth electrode 20B is connected between the receiving electrodes 18B and 18B.
, 20B are provided to prevent adverse effects due to electrostatic capacitance interference between each receiving electrode 18A, 188 and from others.

In this way, these first and second receiving electrodes 18A
and 18B, a voltage V having the same phase with respect to the amount of rotational displacement of the rotary plate 10; will be induced.

A first receiving electrode 1 is installed on the rotary plate 10.
8A and each voltage obtained at the second receiving electrode 18B.

The first fixing plate 30 and the second
A first output electrode 22A and a second output electrode 22B are provided on each surface of the fixed plate 32.

The first output electrode 22A is provided in a ring shape on the surface of the first fixing plate 30 on the inner peripheral side of the first transmitting electrode 14A via the first ground electrode 24A. Further, the second output tube ff122B is provided in a ring shape on the surface of the second fixing plate 32, inside the second transmitting electrode 14B via the ground electrode 24B.

The first receiving electrode 18A is connected to the first fixing plate 3.
Similarly, the second receiving electrode 18B is formed to face both the first transmitting electrode 14A and the first output electrode 22A provided on the second fixing plate 32. The second transmitting electrode 14B provided above and the second
The output electrodes 22B are formed to face each other across both sides of the output electrodes 22B.

In this way, these first and second receiving type Fi18
A and 18B, and the first and second output electrodes 22 described above.
A and 22B are electrostatically coupled, and a voltage V is induced from the first and second output electrodes 22A and 22B at the first and second receiving electrodes 18A and 18B. will be output.

Then, a detection signal V is output from these first and second output electrodes 22B. are synthesized in the detection circuit 36 and then compared with the reference voltage V1, and the amount of rotational displacement of the rotary plate 10 is detected based on the phase difference φ.

Thus, according to the present invention, the first and second fixing plates 30
and 32, two sets of transmitting electrodes, that is, first and second transmitting electrodes 14A and 14B are provided, and rotation of the rotary plate 10 is performed by first and second receiving electrodes 18A and 18B provided on the rotary plate 10. Signal V corresponding to displacement ■. can be obtained respectively.

and the signal V of the first and second receiving electrodes 18A and 18B. is taken out from the fixed plates 30 and 32 side by electrostatic coupling with two sets of output electrodes 22A and 22B provided on the first and second fixed plates 30 and 32, and the amount of rotational displacement of the rotating plate 10 is detected. ing.

As described above, according to the present invention, the signal V corresponding to the amount of rotational displacement of the rotary plate 10 is generated through two series of electrostatic coupling. Two sets of V are generated, and a signal V obtained from both of these series is obtained. is synthesized on the output electrode 22 side to detect the amount of rotational displacement of the rotary plate 10. Therefore, the amount of rotational displacement of the rotary plate 10 is detected by combining the two on the output electrode 22 side. The amount of rotational displacement of the rotating plate 10 can be detected with detection resolution.

Therefore, for example, as shown in FIGS. 6 and 7, when trying to obtain the same detection resolution as an encoder having only one transmitting electrode 14 formed by arranging 32 unit electrode plates in a ring shape, As in this embodiment, the first transmitting electrode 14A and the second transmitting electrode 14B may be formed using 16 unit electrode plates 14a and 14b, respectively. At this time 1
The radius of the first and second transmitting electrodes 14A and 14B, which are formed by arranging six unit electrode plates in a ring shape, is significantly smaller than that of the transmitting electrode 14 which is formed by arranging 32 unit electrode plates in a ring shape. Therefore, when the encoder of the present invention obtains the same resolution as the conventional encoder, it is possible to sufficiently reduce the size in the direction of the radius of rotation and to downsize the encoder itself.

Further, according to the present invention, two sets of signals (2) corresponding to the amount of rotational displacement of the rotating plate 10 are generated through two series of electrostatic couplings having different physical paths. is generated, so by combining these two sets of signals, their error components cancel each other out,
Even if eccentricity, deflection, inclination, etc. exist in each of the fixed plates 30, 32 and the rotary plate 10, it is possible to accurately detect the amount of rotational displacement of the rotary plate 10 without being affected by these.

Specific Application Example FIG. 3 shows a case where the capacitive encoder according to the present invention is used in a measuring device for measuring the inner diameter of a workpiece.

The measuring device of the embodiment includes an inner diameter measuring element 42 that is provided at the tip of a frame body 40 formed in a cylindrical shape and moves forward and backward in the radial direction indicated by arrow Y, and an inner diameter measuring element 42 that is housed in the frame body 46 and moves in the axial direction indicated by arrow Z. The probe 4 moves forward and backward with its tip 44.
a spindle 46 that abuts the inside of 2.

In the embodiment, the measuring element 42 is attached to the frame body 40.
Three probes 42 are provided at an angular interval of 120 degrees at the tip of the probe 42, and each probe 42 is urged inward by a leaf spring 48 and comes into contact with the tip 44 of the spindle 46.

Here, the tip 44 of the spindle 46 is formed into a conical shape, and the inner surface of each probe 42 is cut out so as to abut along the conical shape of the tip 44.

The measuring device of the embodiment rotates the simple 50 provided integrally with the spindle 46, and
By moving 6 forward and backward in the axial direction indicated by arrow Z,
The tip portion 44 moves the probe 42 forward and backward in the radial direction.

Therefore, by detecting the state in which the three probes 42 provided at the tip of the frame body 40 are in contact with the inner surface of the workpiece at three points, the inner diameter of the workpiece is detected as the amount of displacement of the spindle 46 in seven directions. be able to.

The device of the embodiment detects the amount of displacement of the spindle 46 using the encoder according to the present invention, and inputs an electric signal pulse corresponding to the detected amount of displacement to the counting circuit. The counting circuit counts the electrical pulse signals output from the encoder, and digitally displays the counted value on a digital display provided on the side surface of the frame body 40.

The encoder used in the device of this embodiment includes first and second rigid plates 30 and 32 fixed to the frame body 40.
and a rotary plate 10 that is provided between the first and second fixed plates 30 and 32 and rotates according to the movement of the spindle 46.
and, including.

The first and second fixing plates 30.32 are formed in a donut shape, and have insertion holes 30a, 3 provided in the center thereof.
A spindle 46 is inserted through 2a so as to be movable forward and backward, and is fixed to a base 52 of the frame body 40.

Further, the rotating plate 10 is also formed in a substantially donut shape, and is disposed on a rotating cylinder 54 rotatably provided around the spindle 46 so as to face the first and second fixed plates 30° 32. .

Here, the rotating cylinder 54 is provided with an engaging pin 56 on its inner periphery, and this pin 56 is engaged with a keyway 58 provided on the outer periphery of the spindle 46 along the forward and backward direction thereof.

Further, a thrust angular contact bearing 60 is provided to prevent displacement of the rotating cylinder 54 in the spindle axial direction.

Therefore, when the simple 50 is rotated and moved forward and backward in the axial direction indicated by 7 in the figure while rotating the spindle 46, the rotating cylinder 54 is not displaced in the spindle axial direction due to the engagement between the bottle 56 and the keyway 58. According to the amount of displacement of the spindle 46, the rotating plate 10 is rotated while maintaining a constant clearance between the first and second fixed plates 30 and 32.

Therefore, according to the measuring device of the embodiment, the displacement of the measuring element 42 in the radial direction indicated by the arrow Y is accurately detected as a flat rotational displacement of the rotary plate 10 using the encoder of the present invention, and as a result, It becomes possible to accurately measure various inner diameters of the workpiece.

Furthermore, in the embodiment, the encoder of the present invention is
Although the present invention has been described using an example of application to a measuring device for measuring the inner diameter of a workpiece, it goes without saying that the present invention is not limited to this and can be applied to micrometers, dial gauges, microgauges, and other measuring devices.

[Effects of the Invention] As explained above, according to the present invention, it is possible to obtain a capacitive encoder that is capable of downsizing the entire device and detecting a rotational displacement gate of a rotary plate with high detection accuracy. .

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a preferred embodiment of the capacitive encoder according to the present invention, FIG. 2 is an explanatory diagram showing the electrode structure of the encoder shown in FIG. An explanatory diagram of the structure of a measuring device using an encoder, Figures 4 and 5 are explanatory diagrams showing the first basic technology of the electrostatic customer type encoder, and Figures 6 and 7 are capacitive type encoders. It is an explanatory diagram showing the second basic technology of the encoder. 10... Rotating plate 14A... First transmitting electrode 14B... Second transmitting electrode 14a... Unit electrode plate 14b... Unit Electrode plate 18A... First receiving electrode 18B... Second receiving electrode 22A... First output electrode 22B... Second output electrode 30... First fixing plate 32... - Second fixing plate.

Claims (3)

[Claims] (1) A rotating plate rotatably provided on the main body, and a first fixing plate and a second fixing plate fixed to the main body so as to face each other via the rotating plate, and the first fixing plate includes: The fixed plate includes a first transmitting electrode formed by arranging a plurality of unit electrode plates at equal intervals along the circumference in a ring shape to which alternating current voltages with different phases are applied, and an inner circumference of the first transmitting electrode. a first output electrode disposed on the side with a shield ring interposed therebetween, and the second fixing plate is provided with a first
a second transmitting electrode formed by arranging a plurality of unit electrode plates in a ring shape at equal intervals along the circumferential direction to which an AC electrode having a phase different by 180° from each unit electrode plate of the transmitting electrode is applied; A second plate placed on the inner circumferential side of the
an output electrode, and the rotary plate is provided with a first receiving electrode facing across the first transmitting electrode and the first output electrode, and a second transmitting electrode and a second output electrode. A second electrode facing across the electrode
A receiving electrode is provided, the first receiving electrode and the second receiving electrode are both formed to face a predetermined unit electrode plate to which a common phase AC voltage is applied, and are changed by rotation of the rotary plate. 1. A capacitive encoder that detects the amount of rotational displacement of a rotary plate based on output signals of first and second output electrodes. (2) In the encoder according to claim (1), the first transmitting electrode is composed of 16 unit electrode plates to which alternating current voltages having a phase different by 45° are applied, and the second
transmitting electrodes, one for each unit electrode plate of the first transmitting electrode.
A capacitive encoder comprising 16 unit electrode plates to which alternating current voltages having a phase difference of 80 degrees are applied. (3) In the encoder according to claim (2), the first receiving electrodes are located point-symmetrically on the rotary plate through the center of rotation, and two consecutive sets of the first transmitting electrodes are arranged on the rotating plate. 4
two unit electrode plates and two electrode plates formed to face each other, the second receiving electrode is located on the rotary plate point-symmetrically with respect to the center of rotation, and the second receiving electrode is located on the rotating plate in point symmetry with respect to the rotation center, It is characterized by comprising two electrode plates that are provided to have a phase difference of 90° with respect to the electrodes and are formed to face two sets of four consecutive unit electrode plates of the second transmitting electrode, respectively. Capacitive encoder.