JPS62287116A - Capacity type position measuring transducer - Google Patents

Abstract

PURPOSE:To obtain a small-sized, lightweight capacity type position measuring transducer which is driven by a battery by measuring the quantity of relative movement between two scales which move relatively as the absolute value of variation in electrostatic capacity. CONSTITUTION:The 1st scale 10 and the 2nd scale 20 are arranged closely to each other so that they move relatively. The scale 10 is provided with the 1st transmitting electrodes 12 and supplied with an AC signal from an oscillator 30. The scale 10 is further provided with (n) arrays of the 1st receiving electrodes 14, which are connected to a measuring circuit 32 respectively. The scale 20, on the other hand, is provided with the 2nd arrayed receiving electrodes 22 and (n) arrays of the 2nd transmitting electrodes 24; and the electrodes 22 are capacity-coupled with the electrodes 12 and the electrodes 24 are capacity- coupled with the respective arrays of the electrodes 14. Further, the electrodes 22 and the arrays of the electrodes 26 and the electrode 22 and 24 are displaced as shown by a code D(X). Therefore, a detected electrostatic capacity value corresponds to the displacement D(X) and absolute value measuring operation is performed.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a capacitive position measuring transducer, and more particularly, to a capacitive position measuring transducer, and more particularly, to a capacitive position measuring transducer for statically determining the absolute position between a pair of moving members that move relative to each other. This invention relates to an improved capacitive position measuring transducer capable of accurately measuring changes in capacitance: 1-11.

[Prior art] As an electric length measuring device, two scales are moved relative to each other,
An electrical length measuring device that measures the relative movement position of both scales using changes in capacitance between electrodes arranged on both scales is well known, and is suitable for use in large scale devices such as three-dimensional measuring instruments or NC processing machines. It can be used in a wide variety of ways, from length measuring instruments to portable calipers, micrometers, and other small length 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 general capacitive transducers usually perform relative measurements and are unsuitable for absolute measurements.

However, the IQ1 between both scales of the transducer
J-movement 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. Measuring the absolute position itself is extremely rotational, and relative measurement has been common in which both scales are relatively moved from the reference position to the measurement position and the repeated signals during this period are counted.

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

Further, in the above-mentioned relative measurement, there is a problem that restrictions are imposed on the speed of movement between both scales, and power consumption is large.

That is, according to the above-mentioned relative measurement, the measurement must be performed incrementally, and the device always needs to be zeroed at the beginning of each measurement.

Therefore, conventional relative measuring devices have poor operability and consume a large amount of power, so that small battery-powered measuring devices often have problems such as short battery life or large devices.

In addition, as mentioned above, in relative measurement, when the moving speed between both scales becomes faster, there is a problem that the processing speed cannot keep up and miscounts occur, which limits the moving speed or increases the frequency of the AC signal. There is a problem in that it is necessary to make the detection circuit sufficiently high and the processing speed of the detection circuit sufficiently high.

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 each measurement value is not required at all. In addition, since absolute measurement only requires connecting the power supply when obtaining a measured value, power consumption is significantly reduced, making it possible to use compact battery-powered length measuring instruments, and even with small power supply capacity such as solar cells. It has the advantage that the length measuring device can be sufficiently driven by a battery.

Furthermore, according to absolute length measurement, the capacitance between both scales is measured when their relative positions are determined, so there is no difference in length measurement during relative movement of the scales! As a result, there is an advantage that no restrictions are imposed on the moving speed of the scale.

Conventionally, an absolute position measuring transducer using capacitance has been disclosed in Japanese Patent Application Laid-Open No. 54-94354 (US Pat. No. 44).
No. 20754), 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 The pitches are different from each other, and 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, the conventional device has several problems as described below when it is put into practical use as a length measuring device.

The first problem is that the two pairs of scales are independent of each other and constitute separate capacitance detection circuits, and these rain detection outputs are processed by the measurement circuit, but there is inevitably a slight time difference in the dual-purpose capacity. However, there was a problem in that this time difference caused a large error in the measured values.

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 Any 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 independently installed electric A frequent problem was that the processing characteristics of the circuit had to be set very 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 devices. .

The third problem is, as mentioned above, in the conventional device,
Since the two pairs of scales are used separately as capacitance detection circuits, power consumption increases, which is also an unfavorable characteristic for a small portable length measuring device.

The present invention has been made in view of the above-mentioned conventional problems,
The purpose is to provide an improved capacitive position transducer that electrically measures the absolute position between relatively moving scales using a capacitive method, and eliminates all of the aforementioned problems with conventional devices. It's about doing.

According to the present invention, it is possible to perform accurate absolute value measurement while using a small transducer, and there is no need for zero setting each time a measurement is made, and improvements are made that consume less power and have 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, thereby significantly simplifying the electric circuit. Moreover, the device can 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 of a transducer that measures the absolute position between two relatively moving members by measuring capacitance. The deuser has a first scale and a second scale that are disposed close to each other so as to be relatively movable as the relatively movable members.

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) of first transmitting electrodes to which an alternating current signal is supplied, and first receiving electrodes that are arranged in close proximity to the first transmitting electrodes in an insulated state and to which a measuring circuit is connected.
n is an integer of 2 or more).

On the other hand, the second scale is made up of a group of electrodes arranged at a position that can face the first transmitting electrode along the relative movement direction.
A second receiving electrode capacitively coupled with the transmitting electrode, and a group of electrodes similarly arranged at a position facing the first receiving electrode along the direction of relative movement, and capacitively coupled with each row of the first receiving electrode. a second transmitting electrode of the column.

Both electrodes provided on the second scale are arranged continuously over the required measurement area, and usually form an electrode row that is sufficiently longer than the electrodes on the first 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 pair of electrode groups of the second receiving electrode and the second transmitting electrode, and that the deflection is The position is different for each row of the second transmitting electrodes, and absolute value measurements are made with said excursions identified 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 and can be any arbitrary function. can be given the following 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 first
The AC signal supplied to the first transmitting electrode of the scale 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 of each column. , and are returned to the first receiving electrodes of the respective columns facing each other 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 deviation between the electrodes can be detected at once. is uniquely determined for each moving position in each row of electrodes between the required measurement areas, so the capacitance value detected by selecting one row of electrodes is determined by the phase of the supplied alternating current signal. It is determined to be a single value corresponding to , and unlike conventional devices that use two series of electric circuits, it is possible to perform extremely high-precision measurement operations.

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 deflections are given to the second transmitter electrodes in each row, it is possible to obtain various absolute measurement ranges with one device, and also to obtain high It is also possible to perform accurate measurements.

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

FIG. 1 shows a preferred embodiment of the capacitive position detection 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. It includes a first scale 10 and a second scale 20, and 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 scale side.

Both scales 10 and 20 are arranged close to each other so as to be movable relative to each other, and in FIG. 1, the X-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 three-pair first transmitting electrode structure consisting of two equally spaced electrodes, and each row receives alternating current signals of different phases from the oscillator 30. 30a and 30b are supplied, and the phase difference between both signals is set to 180 degrees.

The first scale 10 is further provided with n rows (n is an integer of 2 or more) of first receiving electrodes 14 (in this figure, a second receiving electrode 14 is provided).
In the embodiment, the first receiving electrodes 14 consist of a group of electrodes arranged at predetermined intervals for each column, and are arranged adjacent to and parallel to the first transmitting electrodes. There is.

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,
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, and as is clear from the figure,
The second scale 20 has second receiving electrodes 22 arranged in alignment.
and n rows of second transmitting electrodes 24 (up to the second row are shown in this figure).

The second receiving electrode 22 is connected to the first receiving electrode 22 along the relative movement direction (X-axis).
It consists of a group of electrodes arranged at a position that can face the transmitting electrode, 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 row are composed of a group of electrodes arranged at positions that can face the first receiving electrodes 14 in the n rows along the relative movement direction (X axis), They are capacitively coupled to each row of the first receiving electrodes 14, respectively.

In one row, the second transmitting electrodes 24 are as follows:
The electrode groups are arranged at equal intervals, and the pitch Pt2 is different for each row.

In the present invention, the second receiving electrode 22 and the second
The pitch with the transmitting electrode 24 is set to a different value,
As a result, it is understood that a deviation indicated by the symbol D(X) is given between both electrodes.

In the present invention, the deviation [)k(x)=(Pt2(k)-Pr2)f(X > is characterized in that it takes a fixed specified value depending on the relative movement position, that is, the value of x.

Further, in the present invention, the second receiving electrode 22 and the second transmitting electrode 24 in each row are connected to each other by a coupling electrode 26 for each electrode.
It is characterized by being electrically connected by.

Therefore, according to the present invention, for each relative movement position (X), the inter-electrode deviation Dk(x) of each column coupled to each other by the coupling electrode 26 is a unique specified value for each column. It is understood that the detected capacitance value is the deviation Dk(x), which is the only identified value for each column, and thereby the detected capacitance value is It is understood that the value corresponds to the deviation D(X), and absolute value measurement becomes possible.

However, the deviation Dk(X) of each column increases as the measurement range of the transducer increases; There is a υ1 rule that the transmission wavelength pitch Wt1 cannot be exceeded.

That is, the deviation Dk(X) is the transmission wavelength pitch Wt1
This is because if the value exceeds 1, it becomes difficult to identify the received signal.

Therefore, in the embodiment of FIG.
The maximum deviation Dk(X) of each row of the second transmitting electrode 1 pole 24 over the entire length of the caliper is the transmitting wavelength pitch Wt1.
is set not to exceed. More specifically, the first
Each deviation [)k(X> in the figure is set to be zero at the center of the second scale 20, and its value increases in the opposite direction as it moves left and right.
It has a shape in which the deviations at both ends of 0 are distributed to the main negative.

The second scale 20 also has an insulating substrate, and the aforementioned second receiving electrodes 22, n rows of second transmitting electrodes 24, and each coupling electrode 26 are formed on the insulating substrate by vapor deposition or other means. The corresponding second receiving electrode 22 and the second
The transmitting electrodes 24 are electrically connected, and such electrode pairs are arranged in a state of being electrically insulated from each other along the relative movement direction (X-axis).

As described above, according to the present invention, the second receiving electrode 22 of the second scale 20 and the second transmitting electrode 24 of each row have a unique deviation Dk(
X), the capacitance value detected when the first scale 10 moves becomes a unique 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 power by capacitive coupling, and this is immediately transmitted to the second transmitting electrode of each column by conduction of the coupling electrode, After being shifted in the relative movement direction (X-axis direction), it is returned to the first receiving electrode 14 of each corresponding column by capacitive coupling.

Therefore, according to the present invention, 111-
It becomes possible to detect signals through the electrodes having different deviations using only the electrical system of the above, and it is possible to perform absolute measurement with extremely high precision without causing positional deviation or time difference of the signals. .

FIG. 2 shows another embodiment of the first scale according to the present invention, and the same or corresponding members in FIG.

In the embodiment, the first transmitting electrode 12 is supplied with alternating current signals at four different positions, and for this reason, the first transmitting electrode 12 is designated by the symbols "11" to "4".
One block is formed for each of the four electrodes shown in , and AC signals with different phases of 90 degrees are sent to the transmitter 30.
is supplied 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 7, in the example, Z=4, and each group electrode That is, the transmission wavelength pitch W
It is understood that t1 is /×10.

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 first receiving electrode 1 in the first row
The pitch of each block in 4-, that is, the reception wavelength pitch Wrl, corresponds to the shift amount by which the transmission signal passes through the second scale and is shifted by a predetermined amount as described above. ) /
It is set to Pr2.

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

Measurement signal 32-1゜32-2 output to the measurement circuit 32
．． . . 32-n, one of them is selected by an analog switch in the circuit 32, and a predetermined wave node is completed.

In addition, in the range 1- that can be absolutely measured by the second transmitted voltage and pole in the second column, the deviation Dk (x) is the transmitted wavelength pitch W
Assuming that the pitch Pt2 (k) of the second transmitting electrode is smaller than the pitch pr2 of the second receiving electrode under the condition that tl is not exceeded, mr't2 (k)= r2 = Lk + Wr1 1 k = WrI xp↑2 (k) / (Pr2-Pt2 (k)) ... (1)
In a range where the amount of relative movement exceeds the absolute measurable range 1k, the phase changes by 360° or more, making it impossible to specify the absolute value.

J3, the pitch of the second transmitting electrode from equation (1) r)12(
k) to the pitch pr2 of the second receiving electrode, that is, the deviation Dk(X) is reduced. be done.

FIG. 3 shows an example of the arrangement of the second wetting electrode 22 of the second scale and the second transmitting electrodes 24-1 to 24-n in n rows according to the present invention. ; The pitch Pt2 between each electrode of the electrodes 24 is gradually decreased from the first row to the nth row.

′? 1, that is, they are arranged so that the deviation Dk (X) of each column gradually increases.

In this way, by setting the second transmitting electrodes 24 in each row to different pitches, 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 in order to output signals with two different phases. , the electrode also has a triangular wave shape that repeats at a reception wavelength pitch Wr1 with Q=J in the relative movement direction (XIIil).

This triangular wave shape consists of two waves arranged in opposite phases to each other.
The first receiving electrodes 14a and 14b are used to calculate the difference between the detected values of the first receiving electrodes 14a and 14b, thereby improving the sensitivity of the detected signal.

b) The first scale 10 shown in FIG. 5 is similar to the embodiment shown in FIG.
is characterized by having a sine wave shape, unlike the triangular wave shape shown in FIG.

Further, in the first scale 10 of FIG. 5, the AC signal supplied to the first essential electrode 12 is divided into eight phases 1111, each having a phase difference of 45 degrees.

u15] In the first scale 10 as shown in the figure, the first
Rectangular wave No. 111 is selected as the AC signal supplied to the transmitting electrode 12, and the first receiving electrodes 14a, 14b of each column
Since the electrode shape is a sine wave, the measurement circuit 32
It will be understood that the two types of inverted phase output signals supplied to the output signal 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 immediately shifts the second transmitting electrode provided in n rows by a predetermined displacement amount. The detected output signal is shifted and conductive and returned to the first receiving electrode of each row facing each other by capacitive coupling, and this detected output signal is converted to the polarization of the second receiving electrode and the second transmitting electrode for each row on the second school. In the present invention, this deviation IJ always has a unique specified value for each column for the relative movement position within the necessary measurement area, so
As a result, one detected word in one selected column is sufficient to calculate the relative movement position 'cL 'l'l"J
lj 'g (This means that it is held.

According to the present invention, accurate absolute measurement is possible by measuring the deviation Dk(X) described above, and there is no need for zero setting, large power consumption, and scale movement speed that are required for each measurement in conventional relative measurement. We can provide excellent length measuring instruments.

Further, according to the present invention, as described above, the second feed 11.
Since there is only one electric circuit passing through the transducer voltage and the first receiving electrode for each row, mechanical errors in electrode placement or electrical delay time differences must be taken into account. By providing each n rows of the first receiving electrode 14 and the second transmitting electrode (24), various absolute measurement ranges can be obtained, and the measurement accuracy of each row can be significantly improved. By combining the values, the measurement accuracy can be further increased, and since the measurement is performed using a pair of original scales, it is possible to provide a transducer that consumes less space and power.

FIGS. 6 and 7 show an example of a length measuring circuit connected to the lance ducer according to the present invention described above, and the waveforms and timing charts of each part h/J"i: 8
As shown in the figure.

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 having one type of voltage, as in the embodiment shown in FIGS. 1 and 2. The above-described transducer according to the present invention is designated by the reference numeral 100, and a plurality of alternating current signals having different phases are supplied to the first transmitter +tU. 3
In the present invention, this output power fo does not need to be very high frequency, for example, 100 to 200K.
The frequency can be relatively low, on the order of Hz.

The output fo of the optical imager 30 is supplied to the transducer 1Q○ as a signal whose frequency is further divided by a frequency divider 60, but it is also used as a synchronizing signal for the modem, and is used as a synchronizing signal for the device. This is one of the factors for determining the resolution, and as mentioned above, in the present invention, since this fundamental frequency and the frequency of the AC signal that is then divided and supplied to the first transmitting electrode are low, the circuit configuration The objective is to simplify the process and obtain sufficient resolution with an inexpensive device.

The output of the front F, C frequency divider 60 is further converted by the phase converter 34 into AC signals 200-1 to 200-8 having a phase difference of 45 degrees each for eight desired cycles, as shown in FIG. . Therefore, it is preferable that these eight alternating current signals having different phases be supplied to the first rejection electrode shown in FIG. 5, for example.

The above-mentioned AC signal 8([ii) is modulated by the output fO of the oscillator 30 in the modulator 62, and this signal
0-1 to 200-8 are supplied to each first transmitting electrode 12 of transducer '100.

As described above, the transducer 100 converts the supplied AC signal 202 into the first . After performing signal level conversion corresponding to the relative movement position of the second scale, it is output as an electrical signal from each column of the first receiving electrode. The output from which the column signal is 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; the output horn signal 204 is demodulated by a synchronous demodulator 66, and the circuit configuration is the same as that shown in FIG. 6.

The output 206 from the synchronous demodulator is based on both scales i%I-
Compared to the reference signal 300 when the position is φ (1
By finding this phase difference φ,
The absolute value determined by the relative positions of both scales can be determined.

Note that the output 206 of the demodulator 66 includes high frequency components as shown in the same vehicle in FIG. ing.

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

In an embodiment, in order to digitally calculate the phase difference φ, the apparatus includes a counter 72, the start/receipt signal of which, in the embodiment, is applied to a modulator 62. Demodulator 66
The measurement start of the apparatus is used as a trigger for the reference signal, and the counting operation of the counter 72 is started from this point. The counting timing of the counter 72 is controlled by the output frequency fO of the oscillator 30.

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.
A stop signal is output from the output 208 to the counter 72, and the operation of the counter 72 ends at this point.

Therefore, the counted value of the counter 72 indicates the ()7 phase difference obtained by shifting the reference signal 300 by the transducer, and as described above, according to the present invention, this phase difference φ is Corresponding to the deviation D(X) of .20, the output of the force r Kuntaf 2 is converted into a direct force by the 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 made of, for example, a liquid crystal display embedded and fixed in the surface of the caliper.
This allows the user to easily read the measured length value.

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

Further, according to the present invention, the second receiving electrode on the second scale side and the second transmitting electrode in the n rows are electrically connected to each other by the coupling electrode, and the distance between the two electrodes is adjusted along the relative movement direction. Each column has a different deviation, and this deviation is set to be a unique specified value for each column in the entire length measurement range, and the output signal of one column of the first transmitting electrode By selecting and performing predetermined calculations, the transmitting and receiving signals 8 can be transmitted and received using a single capacitive coupling circuit that passes between both scales.
t('i
It becomes possible to know the versus value.

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.

Historically, each column uses a single capacitive coupling circuit, significantly reducing interference from mechanical and electrical errors.
Furthermore, it is possible to obtain a small transducer with low power consumption.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of essential parts showing a preferred embodiment of a capacitive position measuring transducer according to the present invention, and FIG. 2 is a schematic diagram showing an embodiment of the first scale side of the transducer according to the present invention. An explanatory drawing, FIG. 3 is a partial schematic diagram showing an embodiment of the second scale side of the transducer according to the present invention, and FIG. A schematic explanatory diagram showing an example, FIG. 5 is a plan view showing another first scale of the transducer according to the present invention, and FIGS. 6N and 7 are diagrams of a measuring circuit suitable for the transducer according to the present invention. Block diagram FIG. 8 is an explanatory diagram showing the waveforms and timing charts of FIGS. 6 and 7. 10... First scale 12... First transmitting electrode 14... First receiving electrode 20... Second scale 22... First receiving electrode 24... First transmitting electrode 26... Coupling electrode 30... Oscillator 32... Measurement circuit D(x)... Deflection X... Relative movement direction. Applicant Sanfi1 Co., Ltd. Representative Patent Attorney Kenji Yoshida [8-8] (2 others)

Claims (6)

[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; n columns (n is an integer greater than or equal to 2) arranged insulated from each other and connected to measurement circuits.
a first receiving electrode, and the second scale is provided with a first receiving electrode along the relative movement direction.
a second receiving electrode that is capacitively coupled to the first transmitting electrode, which is comprised of an electrode group arranged at a position that can face the transmitting electrode; and an electrode group that is arranged at a position that can face the first receiving electrode along the relative movement direction. n rows of second transmitting electrodes capacitively coupled to each row of first receiving electrodes, and the second receiving electrodes and the second transmitting electrodes of each row are electrically connected to each other by coupling electrodes. A different deviation is given to each row of the second transmitting electrodes along the direction of relative movement between the connected second receiving electrodes and second transmitting electrodes. A capacitive position-measuring transducer, characterized in that an absolute measurement is made with said deflection determined for each relative displacement position in the column. (2) In the transducer according to claim (1), the first transmitting electrode is configured such that a group of successively adjacent electrodes forms one block, and alternating current signals with different phases are supplied to the first transmitting electrode of each group. , a capacitive position measuring transducer characterized in that, when the pitch of one block is defined as a 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), the first receiving electrode of an arbitrary k-th column (1≦k≦n) of the first receiving electrodes of n columns
If the pitch of the 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(k), then Wr1(k) = Wt1× A capacitive position measuring transducer characterized in that Pt2(k)/Pr2 is set. (4) In the transducer according to claim (3), each row of the 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. 1. A capacitive position measuring transducer comprising an electrode having: (5) A 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) A 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.