JPH0435690B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a capacitive position measuring transducer, and more particularly, to a capacitive position measuring transducer that accurately determines the absolute position between a pair of movable members that move relative to each other from changes in capacitance. The present invention relates to an improved capacitive position transducer capable of making measurements.

[Prior art] An electrical length measuring device that moves two scales relative to each other and measures the relative movement position of both scales using changes in capacitance between electrodes arranged on both scales. Length measuring instruments are well known and can be used in a wide range of ways, from large measuring instruments such as three-dimensional measuring instruments or NC processing machines to portable calipers, micrometers, and other small measuring instruments.

A capacitive transducer used in such a length measuring device supplies an alternating current signal, preferably a plurality of alternating current signals with different phases, to its transmitting electrode, and an electrical measuring circuit to the corresponding receiving electrode. The two electrodes are connected to each other, and a predetermined position is measured using changes in capacitance due to relative movement between both electrodes.

Conventional capacitive transducers generally perform relative measurements and are unsuitable for absolute measurements.

In other words, the relative movement between both scales of the transducer is usually electrically detected as a repeated change in capacitance, and conventionally, the amount of relative movement is usually measured by counting the number of repetitions. In such cases, it is extremely difficult to measure the absolute position itself between both scales, and relative measurement is generally performed by moving both scales relatively from the reference position to the measurement position and counting the repeated signals during this time. It was hot.

However, it is not possible to easily obtain measured values with such relative measurements, and absolute measurements have been strongly desired, especially for portable calipers and the like, in view of their operability.

Further, in the above-mentioned relative measurement, restrictions were imposed on the speed of movement between both scales, and there were also problems in that power consumption was large.

That is, according to the above-mentioned relative measurements, the measurements have to be made incrementally and always require a zero-setting of the device at the beginning of each measurement.

Therefore, conventional relative measuring devices have poor operability and
Furthermore, since the power consumption is large, a small measuring device that is powered by a battery has a problem that the battery life is short or the device becomes large.

In addition, as mentioned above, in relative measurement,
If the movement speed between both scales becomes faster, there is a problem that the processing speed cannot keep up and miscounts occur, so the movement speed is restricted or the frequency of the AC signal is made sufficiently high and the processing of the detection circuit is The problem was that the speed had to be increased sufficiently.

On the other hand, according to absolute measurements, if the transducer is zero-set at the time of assembly, there is no need to adjust it during subsequent measurements, and zero-setting at nominal measurements is not required at all. And since absolute measurement requires connecting the power only when obtaining the measured value,
This has the advantage that power consumption is significantly reduced, making it possible to use a battery-powered compact measuring instrument, and that even a battery with a small power supply capacity, such as a solar battery, can sufficiently drive the length measuring instrument.

Furthermore, according to absolute length measurement, since the capacitance between both scales is measured when their relative positions are determined, there is no contribution to the length measurement action during the relative movement of the scales, and as a result, the scale This has the advantage that there are no restrictions on the moving speed of the robot.

Conventionally, an absolute position measurement transducer using capacitance has been disclosed in Japanese Patent Application Laid-Open No. 54-94354 (US Patent No.
4420754), and this prior art was invented by the inventor of the present application, and its general structure is to move two pairs of transmitting/receiving electrodes relative to each other, and both pairs of electrodes are moved at their electrode pitches. The absolute position can be measured by electrically processing signals with different phases obtained from both electrode pairs or both scale pairs.

[Problems to be Solved by the Invention] However, when the conventional device is put into practical use as a length measuring device, there are several problems as described below.

The first problem is that the two pairs of scales are independent of each other and constitute separate capacitance detection circuits, and both of these detection outputs are processed by the measurement circuit, but there is inevitably a slight difference between the two outputs. There was a problem in that a time difference occurred, and this time difference caused a large error in the measured value.

In addition, if there is a slight measurement error between both scale pairs, that is, one scale is performing accurate phase detection, but the other scale has a slight measurement error, in principle, such a The deviation that occurs on one side will be treated as an extremely large absolute value error when the measurement circuit judges the absolute position, and the mechanical position accuracy of both scales and the independent electric circuit described above will be processed. There was a problem in that the characteristics had to be set extremely strictly. The second problem is that the transducer requires two pairs of scales, which increases the space required for the transducer, and this has been a major impediment to the practical application of small, portable length measuring instruments. .

The third problem is that, as mentioned above, in conventional devices, two pairs of scales are used as separate capacitance detection circuits, which increases power consumption. This was an unfavorable characteristic for people.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to electrically measure the absolute position between relatively moving scales using a capacitance method, and to solve the above-mentioned problems in conventional devices. An object of the present invention is to provide an improved capacitive position transducer that eliminates all points.

According to the present invention, it is possible to perform accurate absolute value measurement with a small transducer, and there is no need for zero setting each time a measurement is made, and improvements are made in which power consumption is low and there are no restrictions on the moving speed of the scale. transducers are available.

According to the present invention, even if the frequency of the AC signal connected to the transmitting electrode is set to a relatively low frequency, sufficiently high accuracy can be ensured.
This significantly simplifies the electric circuit and allows the device to be completed at low cost.

Of course, in the present invention, if the power supply is connected only when displaying absolute values, the desired measurement action can be performed, and the power consumption of the device is significantly reduced.

[Means for Solving the Problems] In order to achieve the above object, the present invention relates to an improvement in a transducer that measures the absolute position between two relatively moving members by measuring capacitance. The transducer includes first transducers that are movably disposed close to each other as the relatively movable members.
It has a scale and a second scale.

Generally, both scales are formed in a straight scale and move linearly relative to each other, but of course, in the present invention, the scale is formed by two coaxially arranged disks, and a rotary transformer is used. It is also suitable to obtain a deuser.

The first scale has n rows (n rows) of a first transmitting electrode to which an AC signal is supplied, and a first receiving electrode that is insulated from and close to the first transmitting electrode and is connected to a measuring circuit. is an integer greater than or equal to 2).

On the other hand, the second scale is composed of a group of electrodes arranged at a position that can face the first transmitting electrode along the relative movement direction, and a second receiving electrode capacitively coupled with the first transmitting electrode. The second transmitting electrodes include n rows of second transmitting electrodes, which are composed of a group of electrodes disposed at positions facing the first receiving electrodes along the line, and are capacitively coupled to each row of the first receiving electrodes.

Both electrodes provided on the second scale are arranged continuously over the required measurement area, and usually
An electrode row is formed that is sufficiently longer than the electrodes on the scale side.

In the present invention, each row of the second receiving electrode and the second transmitting electrode is electrically connected to each other by a coupling electrode between the transmitting and receiving electrodes.

Furthermore, a characteristic feature of the present invention is that different deflections are given to each connected electrode group combination of the second receiving electrode and the second transmitting electrode along the direction of relative movement; The position is different for each row of the second transmitting electrodes, and absolute value measurements are performed with said deviations determined in one row of electrodes selected for each movement position.

The different deviations for each movement position described above are expressed as a predetermined function of the movement amount, and this function usually has linearity, but in the present invention, it does not necessarily have to be a linear function.
Can be given any characteristics.

In the present invention, as described above, the second receiving electrode provided on the second scale and the second transmitting electrode in each column are connected to each other by a coupling electrode, and as a result, The AC signal supplied to the first transmitting electrode is first transmitted to the second receiving electrode on the second scale side by capacitive coupling, and then,
This signal is electrically transmitted as it is to the second transmitting electrode in each column, and is returned to the first receiving electrode in each opposing column again by capacitive coupling.

Therefore, according to the present invention, a change in capacitance can be detected at once through the second receiving electrode and the second transmitting electrode by one series of electric circuits for each column, and the change in capacitance can be detected at once through the second receiving electrode and the second transmitting electrode. The capacitance value detected by selecting one row of electrodes is equal to the supplied AC, since the deviation of is uniquely determined for each moving position in each row of electrodes between the required measurement areas. A single value is determined in accordance with the phase of the signal, and unlike conventional devices that use two series of electric circuits, it is possible to perform measurement with extremely high precision.

The measuring circuit compares the received signal level with the phase of the transmitted AC signal, performs a predetermined calculation operation, and can display the absolute value of the relative movement position.

Furthermore, since different deviations are given to the second transmitting electrodes in each row, it is possible to obtain various absolute measurement ranges with one device, and by combining the measured values of each row. It is also possible to perform highly accurate measurements.

[Embodiments] Preferred embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a preferred embodiment of the capacitive position measuring transducer according to the present invention, which is suitable for a length measuring device such as a caliper in which a vernier scale moves linearly with respect to a main scale. 1 scale 10 and 2nd scale 2
For example, the first scale 10 is installed on the vernier side of a caliper, and the second scale 20 is installed on the main side.

Both scales 10 and 20 are disposed close to each other and movable relative to each other, and are shown at x in FIG.
The axis position indicates the movement position of the first scale 10 with respect to the second scale 20.

The first scale 10 is provided with a first transmitting electrode 12 , and an alternating current signal is supplied from an oscillator 30 to the first transmitting electrode 12 .

In the illustrated embodiment, the first transmitting electrode 12 has a first transmitting electrode structure of three pairs of two equally spaced electrodes, each pair receiving an alternating current signal of a different phase from the oscillator 30. 30a and 30b
is supplied, and the phase difference between both signals is set to 180 degrees.

The first scale 10 further includes a first receiving electrode 1.
4 are provided in n rows (n is an integer of 2 or more) (in this figure, up to the second row is shown), and in the embodiment, the first receiving electrodes 14 are arranged at a predetermined interval for each row. The first transmitting electrode is arranged adjacent to and parallel to the first transmitting electrode.

Each first receiving electrode 14 is connected to a measuring circuit 32, respectively.

Each of the electrodes 12 and 14 is provided on the insulating substrate of the first scale 10 by vapor deposition or other means, and the two electrodes are electrically insulated.

A characteristic feature of the transducer according to the present invention lies in the electrode arrangement of the second scale 20. As is clear from the figure, the second scale 20 includes the second receiving electrodes 22 arranged in alignment and the second receiving electrodes 22 in the n rows. Transmission electrodes 24 are provided (up to the second row are shown in this figure).

The second receiving electrode 22 is composed of a group of electrodes arranged at a position facing the first transmitting electrode along the relative movement direction (x-axis), and is capacitively coupled to the first transmitting electrode.

The second receiving electrodes 22 in the embodiment are arranged at equal intervals, and the pitch is indicated by Pr2.

On the other hand, the second transmitting electrodes 24-1 to 24-n in each column
is the first of the n columns along the relative movement direction (x-axis)
It consists of a group of electrodes arranged at positions that can face the receiving electrodes 14, and is capacitively coupled to each row of the first receiving electrodes 14, respectively.

In this second transmitting electrode 24, electrode groups are arranged at equal intervals within one row, and the pitch is
Pt2 is different for each column.

In the present invention, the second receiving electrode 2
2 and the second transmitting electrode 24 are set to different values, and as a result, there is a sign D(x) between the two electrodes.
It is understood that the deviation shown by is given.

In the present invention, the deviation Dk(x)=(Pt2(K)-Pr2)f(x) of each row of the second transmitting electrodes 24, for example, the second transmitting electrode 24-k of the k-th row, is It is characteristic that the value becomes a constant specified value depending on the relative movement position, that is, the value of x.

Furthermore, in the present invention, the second receiving electrode 22
and the second transmitting electrodes 24 of each column are electrically connected to each other by a coupling electrode 26 for each electrode.

Therefore, according to the invention, for each relative movement position (x), the interelectrode deviation Dk(x) of each row coupled to each other by the coupling electrode 26 has a unique specified value for each row. It is understood that, by this, the detected capacitance value is the deviation Dk(x) is a unique specified value for each column, and by this,
It is understood that the detected capacitance value corresponds to the deviation D(x), and absolute value measurement becomes possible.

Of course, the deviation Dk(x) of each column increases as the measurement range of the transducer increases, but the amount of deviation Dk(x) increases at the transmitting pitch, in the example, the first transmitting electrode. Transmission wavelength pitch on 12
There is a restriction that it cannot exceed Wt1.

In other words, the deviation Dk(x) is the transmission wavelength pitch.
This is because if it exceeds Wt1, it becomes difficult to identify the received signal.

Therefore, in the embodiment shown in FIG. 1, the second scale 20 has a maximum deviation Dk(x) of each row of the second transmitting electrodes 24 that exceeds the transmitting wavelength pitch Wt1 over the entire length of the caliper. It is set to not.
More specifically, each deviation Dk(x) in FIG. It has a shape in which the deviations at both ends of the scale 20 are divided into negative sides.

The second scale 20 also has an insulating substrate, and includes the aforementioned second receiving electrode 22 and the second transmitting electrode 2 in the n rows.
4, and each coupling electrode 26 is formed on the insulating substrate by vapor deposition or other means, and each corresponding second receiving electrode 22 and each row of second transmitting electrode 24 are electrically connected, such that The electrode pairs are arranged along the direction of relative movement (x-axis) so as to be electrically insulated from each other.

As described above, according to the present invention, the second receiving electrode 22 of the second scale 20 and the second transmitting electrode 2 of each column
4 has a unique specified deviation Dk(x) for each position along the direction of relative movement, so the capacitance value detected when the first scale 10 moves is This is the only specified value for each position, making absolute measurement possible at any position.

According to the present invention, the AC signal supplied to the first transmitting electrode 12 is transmitted to the second receiving electrode by capacitive coupling, and this is immediately transmitted to the second transmitting electrode of each column by conduction of the coupling electrode. The signal is transmitted and returned to the first receiving electrode 14 of each corresponding column by capacitive coupling in a state shifted in the relative movement direction (x-axis direction).

Therefore, according to the present invention, it is possible to detect signals through the electrodes having different deviations using only a single electrical system for each electrode in each row, and the position of the signal can be detected by using only a single electrical system for each electrode in each row. Absolute measurements with extremely high precision can be made without any deviation or time difference.

FIG. 2 shows another embodiment of the first scale according to the present invention, and the same or corresponding members in FIG. 1 are given the same reference numerals, and the explanation thereof will be omitted.

In the embodiment, the first transmitting electrode 12 is supplied with alternating current signals at four different positions, and for this purpose, one block is formed for each of the four electrodes indicated by symbols "1" to "4". , AC signals having phases different by 90 degrees are supplied from an oscillator 30 to each electrode via a phase converter 34.

As is clear from the figure, the pitch between each electrode of the first transmitting electrode 12 is indicated by Pt1, and if the number of AC signals, that is, the number of transmitting electrode groups is z, in the example, z=4, and each group electrode It is understood that the length of , that is, the transmission wavelength pitch Wt1 is z×Pt1.

N rows of first receiving electrodes 14-1 to 14-n arranged adjacent to the first transmitting electrode 12 each supply a detection signal to a detection circuit.

In the embodiment, the pitch of each block of the first receiving electrode 14-K in the Kth column, that is, the receiving wavelength pitch Wr1 is a shift in which the transmission signal is shifted by a predetermined amount through the second scale, as described above. Corresponding to the amount, Wr1(K)=Wt1×Pt2(K)/Pr2 is set.

Therefore, according to such reception wavelength pitch Wr1, the AC signal transmitted from the first transmission electrode 12 has a predetermined pitch between the second reception electrode 22 of the second scale and the second transmission electrode 24 of each column. After the shift is performed, in the first receiving electrodes of each row facing each other again, the receiving electrodes 14 have a length corresponding to the shift amount.
It is understood that it can be received at

Measurement signal 32-1 output to measurement circuit 32,
32-2, . . . 32-n is selected by an analog switch within the circuit 32, and a predetermined calculation is performed.

Furthermore, the absolute measurable range LK by the second transmitting electrode in the kth column is the pitch Pt2 of the second transmitting electrode under the condition that the deviation DK(x) does not exceed the pitch Wt1 of the transmitting wavelength. (K) is the pitch of the second receiving electrode
Assuming that it is smaller than Pr2, it is expressed as mPt2(K)=LK mPr2=LK+Wr1 LK=Wr1×Pt2(K)/(Pr2−Pt2(K)) …(1) for a certain value m, and the relative movement In a range where the quantity exceeds the absolute measurable range LK, the phase changes by more than 360°, making it impossible to identify the absolute value.

Furthermore, from equation (1), the closer the pitch Pt2(K) of the second transmitting electrode is to the pitch Pr2 of the second receiving electrode, that is, the smaller the deviation DK(x), the smaller the absolute measurable range becomes.
It is understood that although LK is expanded, the resolution becomes coarser.

FIG. 3 shows a second receiving electrode 22 of a second scale and a second transmitting electrode 24-1 of an n column according to the present invention.
24-n is shown, and the pitch Pt2 between each electrode of the second transmitting electrodes 24 is gradually decreased from the first row to the nth row. That is, they are arranged so that the deviation Dk(x) of each column gradually increases.

By setting the second transmitting electrodes 24 in each row at different pitches in this manner, various absolute measurement ranges can be obtained on one scale.

FIG. 4 shows another embodiment of the first scale of the present invention, in which n rows of first receiving electrodes 14 each consist of two types of electrodes for outputting signals with two different phases. The electrodes move in the direction of relative movement (x
It has a triangular wave shape that repeats at the receiving wavelength pitch Wr1 with respect to the axis).

This triangular waveform is made up of two first receiving electrodes 14a and 14b arranged in opposite phases to each other, and their detected values are subtracted from each other, thereby improving the sensitivity of the detected signal. can.

The first scale 10 of FIG. 5 is similar to the embodiment of FIG.
4a and 14b are characterized by exhibiting a sine wave shape, unlike the triangular wave shape in FIG.

Further, in the first scale 10 of FIG. 5, the AC signal supplied to the first transmitting electrode 12 is divided into eight phases, each having a phase difference of 45 degrees.

In the first scale 10 as shown in FIG.
A rectangular wave signal is selected as the AC signal supplied to the first transmitting electrode 12, and the first receiving electrode 1 of each column
Since the electrodes 4a and 14b have a sinusoidal shape, it is understood that the two types of output signals with inverted phases supplied to the measurement circuit 32 have a sinusoidal shape.

As described above, according to the present invention, the AC signal supplied to the first transmitting electrode is transmitted to the second receiving electrode by capacitive coupling, and this signal is immediately transferred to the second transmitting electrode provided in n rows. The displacement amount is shifted, the conduction occurs, and the first column of each column facing each other is again capacitively coupled.
The detected output signal is returned to the receiving electrode and is the deviation information for each row of the second receiving electrode and the second transmitting electrode on the second school, and in the present invention, this deviation is within the required measurement area. As a result, the detected signal of one selected column is sufficient to calculate the relative displacement position, since each column always has a unique specified value for the relative displacement position. This means that the information is held.

According to the present invention, the aforementioned deviation DK(x)
It enables accurate absolute measurement by measuring , and eliminates the zero setting and
It is possible to provide an excellent length measuring device without high power consumption and scale movement speed.

Further, according to the present invention, as described above, the second
Since there is only one electrical circuit passing through the transducer for each row of transmitting electrodes and first receiving electrodes,
Measurement accuracy can be significantly improved without considering mechanical errors in electrode arrangement or differences in electrical delay time differences, and by providing each n rows of first receiving electrodes 14 and second transmitting electrodes 24, various In addition to obtaining an absolute measuring range of It is possible to provide a detour.

FIGS. 6 and 7 show an example of a length measuring circuit connected to the transducer according to the present invention, and FIG. 8 shows waveforms and timing charts of each part thereof.

The length measuring circuit shown in FIG. 6 is a length measuring circuit in which the first receiving electrode of each column is connected to a transducer consisting of one type of electrode, as in the embodiment shown in FIGS. 1 and 2, The above-mentioned transducer according to the present invention is indicated by the reference numeral 100, and a plurality of alternating current signals having different phases are supplied to the first transmitting electrode, and the alternating current signals are obtained from the oscillator 30 and In the present invention, the oscillation output f0 does not need to have a very high frequency, and can be set to a relatively low frequency of, for example, about 100 to 200 KHz.

The output f0 of the oscillator 30 is the transducer 1
00 is further divided by the frequency divider 60 and supplied as a signal, which is also used as a synchronizing signal to the modulator and demodulator, and forms one factor for determining the resolution of the device. As mentioned above, in the present invention, since the fundamental frequency and the frequency of the AC signal that is then divided and supplied to the first transmitting electrode are low, sufficient resolution can be achieved by simplifying the circuit configuration and using an inexpensive device. This has the effect that the following can be obtained.

The output of the frequency divider 60 is further processed by a phase converter 34 to convert into eight desired AC signals 200-1 to 200-, each having a phase difference of 45 degrees, as shown in FIG.
Converted to 8. Therefore, such eight AC signals with different phases are, for example, the first signal in FIG. 5 mentioned above.
Preferably, it is supplied to a transmitting electrode.

The aforementioned eight AC signals are modulated by the output f0 of the oscillator 30 in the modulator 62, and these signals 200-1 to 200-8 are transmitted to the transducer 1.
00 are supplied to each of the first transmitting electrodes 12.

As described above, the transducer 100 converts the supplied AC signal 202 into signal levels corresponding to the relative movement positions of the first and second scales, and then converts the supplied AC signal 202 into electric signals from each column of the first receiving electrodes. The output of each column is output by an analog switch 65, and the output of one column selected is further demodulated by a synchronous demodulator 66.

Furthermore, in the case of a transducer in which the first receiving electrodes in each column are composed of two types of electrodes, as shown in FIG. The signal is sent to the dynamic amplifier 64 and output as a signal 204, which becomes a signal whose envelope draws a sinusoidal curve as shown in FIG. This is the only point that differs from the length measuring circuit shown in FIG. 6, and the output signal 204 is demodulated by a synchronous demodulator 66, and the circuit configuration below is the same as that shown in FIG.

By comparing the output 206 from the synchronous demodulator with the reference signal 300 when both scales are at the reference position and obtaining a phase difference of φ, the absolute value determined by the relative positions of both scales can be obtained. can.

Note that the output 206 of the demodulator 66 includes high frequency components as shown in FIG. 8, and in this embodiment, this high frequency component is removed by a filter 68 to obtain a signal 208 from which the high frequency component has been removed. There is.

The waveform zero-crossing position of the signal 208 is further detected by a zero-crossing circuit 70.

In the embodiment, in order to digitally calculate the phase difference φ, the device includes a counter 72 whose reset/start signal is synchronized by the control unit 80 with the trigger signals of the modulator 62 and demodulator 66 in the embodiment. The counting operation of the counter 72 is started from this point using the start of device mounting as a trigger for the reference signal. counter 7
2 counting timing is the output frequency of the oscillator 30
Controlled by f0.

The counting stop of the counter 70 is controlled by the signal from the zero cross circuit 70, and at the phase φ position in FIG. 72, and the counting operation of the counter 72 ends at this point.

Therefore, the counted value of the counter 72 indicates the phase difference by which the reference signal 300 is shifted by the transducer, and as described above, according to the present invention, this phase difference φ is the difference between both scales at the time of measurement. Corresponding to the deviation D(x) of 10 and 20, the output of the counter 72 is converted into an absolute value by an arithmetic unit 74.

The output of the arithmetic unit 74 controlled by the control unit 80 supplies a desired display signal to the display 78 via the display driver 76, so that the measured value is normally displayed digitally.

In this embodiment, the display 78 is, for example, a liquid crystal display embedded and fixed in the vernier surface of the caliper, so that the user can easily read the length measurement value.

[Effects of the Invention] As explained above, according to the present invention, the amount of relative movement between two relatively moving members, usually the first and second scales, can be measured in absolute value as a change in capacitance. This makes it possible to obtain a compact and lightweight capacitive transducer that can be driven by batteries.

Further, according to the present invention, the second scale on the second scale side
The receiving electrode and the second transmitting electrode of n rows are electrically connected to each other by coupling electrodes, and each row has a different deviation between the two electrodes along the relative movement direction, so that the entire length measurement range is This deviation is set to be a unique specified value for each column, and by selecting the output signal of one column of the first transmitting electrode and performing a predetermined calculation, both Using a single capacitive coupling circuit that passes between the scales, it is possible to know the absolute value of the relative movement position of both scales from the shift value between the transmitted and received signals.

In addition, since each row of the second transmitting electrode has a different pitch, it is possible to obtain various absolute measurement ranges with one scale, and to perform highly accurate measurements by combining the measured values of each row. It is also possible to do so.

Furthermore, since each column uses a single capacitive coupling circuit, the interference of mechanical and electrical errors is significantly reduced, and it is possible to obtain a compact transducer with low power consumption.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a main part showing a preferred embodiment of a capacitive position measuring transducer according to the present invention, and FIG.
The figure is a schematic explanatory diagram showing an embodiment of the first scale side of the transducer according to the present invention, and FIG. 3 is a partial schematic diagram showing an embodiment of the second scale side of the transducer according to the present invention. , FIG. 4 is a schematic explanatory diagram showing another embodiment of the first scale of the transducer according to the present invention, and FIG. 5 is a plan view showing another first scale of the transducer according to the present invention.
6 and 7 are block diagrams of a measurement circuit suitable for a transducer according to the present invention, and FIG.
FIG. 8 is an explanatory diagram showing waveforms and timing charts in FIG. 7 and FIG. 7; 10...first scale, 12...first transmitting electrode, 1
4...first receiving electrode, 20...second scale, 22...
First receiving electrode, 24...first transmitting electrode, 26...coupling electrode, 30...oscillator, 32...measuring circuit, D(x)...deflection, x...relative movement direction.

Claims (1)

[Scope of Claims] 1. A first scale and a second scale are arranged close to each other so as to be relatively movable, and the first scale has a first transmitting electrode to which an alternating current signal is supplied, and n rows (n is an integer of 2 or more) of first receiving electrodes arranged insulated from one transmitting electrode and connected to measuring circuits, and the second scale has a relative movement direction. a second transmitting electrode that is capacitively coupled to the first transmitting electrode, and comprises a group of electrodes disposed at a position facing the first transmitting electrode along the
A receiving electrode, and n rows of second transmitting electrodes each comprising a group of electrodes disposed at a position facing the first receiving electrode along the relative movement direction and capacitively coupled to each row of the first receiving electrode. The second receiving electrode and the second transmitting electrode in each row are electrically connected to each other by a coupling electrode, and there is a gap between each connected second receiving electrode and second transmitting electrode along the direction of relative movement. A different deviation is given to each row of the second transmitting electrode, and the absolute measurement is performed using the specified deviation for each relative movement position in the selected one row. Capacitive position transducer. 2. In the transducer according to claim 1, the first transmitting electrodes are sequentially adjacent to each other to form one block, and AC signals having different phases are supplied to the first transmitting electrodes of each group. A capacitive position measuring transducer characterized in that, assuming that the pitch of one block is the transmission wavelength pitch, the deviation does not exceed the transmission wavelength pitch within a measurable scale range. 3. In the device according to claim 2, any K-th column (1≦K≦n) of the first receiving electrodes in the n-column
The pitch of the first receiving electrode group is the receiving wavelength pitch Wr1
(K), the transmitting wavelength pitch is Wt1, the second receiving electrode pitch is Pr2, and the second transmitting electrode pitch is Pt2.
A capacitive position measuring transducer characterized in that, where (K), Wr1(K)=Wt1×Pt2(K)/Pr2. 4. In the transducer according to claim 3, each row of first receiving electrodes is composed of two types of electrodes in order to output signals with two different phases, and the electrodes have mutually inverted shapes. A capacitive position measuring transducer comprising electrodes. 5. The capacitive position measuring transducer according to claim 4, wherein the above-mentioned inverted shape of each row of the first receiving electrodes has a sine wave shape. 6. The capacitive position measuring transducer according to claim 4, wherein the above-mentioned inverted shape of each row of the first receiving electrodes has a triangular wave shape.