JPS6365316A - Optical displacement detecting device - Google Patents

Abstract

PURPOSE:To detect the absolute displacement quantity of relative movement between two scales with high accuracy and to reduce power consumption by intermittent lighting by utilizing the inter-group phase difference between electric signals outputted in relation to two arrays of optical gratings provided to the two scales. CONSTITUTION:A main scale 10 provided with optical gratings 13 and 15 which differ in pitch and an index scale 20 provided with reference optical gratings 23 and 25 which differ in pitch are moved relatively. Then, photoelectric converting elements 33A and 33B which have a 90 deg. phase shift corresponding to the gratings 13 output electric signals which have a phase difference theta1 and photoelectric converting elements 35A and 35B corresponding to the gratings 25 output electric signals which have a phase difference theta2. Here, an absolute displacement detecting circuit 50 samples and holds 51 the electric signals with the phase differences theta1 and theta2 properly to compute 55 inter-group phase difference theta2-theta1, which is utilized to find the absolute value of the relative displacement quantity between the scales 10 and 20 with high resolution and high accuracy. Further, an illumination system 40 is driven intermittently by a driving circuit 70 for a specific time right before the absolute value is detected, so the power consumption is reducible.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is an absolute method that has an optical grating that can be relatively displaced and processes the transmitted light or reflected light from the optical grating in a predetermined manner to detect the amount of relative movement. This optical displacement detection device is particularly designed to reduce power consumption by intermittent driving of the illumination system.

[Background technology and its problems]

2. Description of the Related Art Optical displacement detection devices are widely used as a means of detecting relative displacement between independent objects and determining physical specifications (length, pressure, weight, etc.).

Conventionally, a typical transmission type structure of such an optical displacement detection device has been shown in FIG.

That is, a main scale 10 having optical gratings 13 aligned in the longitudinal direction and an index scale 20 having corresponding reference optical gratings 3A and 3B are attached to each of two opposing objects (for example, a stationary body and a movable body). attachment,
The light source 1 and photoelectric converters 2A and 2B are connected to both scales 10.
A signal detection circuit 7 is disposed integrally with the index scale 20 with 20 in between, and selectively includes a waveform shaping circuit, a dividing circuit, a direction discrimination circuit, etc. for processing the output signals from both photoelectric converters 2A and 2B. , a reversible counting counter 8, and a display means 9 consisting of a digital display or the like. Therefore, if the index scale 20 and main scale 10, which are integrated with the light source 1 and the photoelectric converters 2A and 2B, are moved relative to each other in the direction of the arrow For example, 1 μm/
It was possible to count one pulse of a digital signal with the counter 8, display the amount of displacement on the display means 9, and further output an electric signal corresponding to the amount of displacement to other equipment. The two photoelectric converters 2A and 2B are provided to provide a direction discrimination function, and depending on the division method, they can be used to more than double the resolution. there were.

However, the conventional optical displacement detection device described above has the following problems.

First, since it is an incremental method, it is difficult to operate in an absolute manner.

That is, the photoelectric converter 2A.

The output of 2B is, for example, the slit width of the optical grating 13 by 1
This is because if the pinch is 0 μm and the pinch is 20 μm, a cycle/7 cycle signal having a substantially sinusoidal shape with one period having a length equivalent to 20 μm will be obtained. Therefore, an electromagnetic switch or the like connected to the main scale 10 is installed to set the so-called absolute origin and use a quasi-absolute method, but this changes to an incremental method within the interval between the electromagnetic switches. Not only is it not a fundamental solution because there is no such device, but the provision of electromagnetic switches and other components increases the size, increases the economic burden, and lacks credibility.

On the other hand, an absolute type detection device in which the main scale 10 is equipped with a binary code, a gray code, etc. is also considered, but this type would inevitably increase the size of the equipment and would not be accurate enough to satisfy the current high precision requirements. It has a fundamental drawback in that resolution cannot be obtained, making it difficult to use in industry.

Second, since it is an incremental method, there are inherent problems such as unstable accuracy or accuracy guarantee. Due to noise, etc. during measurement (if there is even one miscount, the value displayed on the display means 9 during the process, that is, the measured value, will be meaningless, and because of the high resolution, the miscount will not be easily noticed) This problem caused a fatal drawback in that product defects could not be avoided.

As a result, not only strict noise countermeasures are required and the equipment becomes too large, but also there is a problem in that the manner of use is restricted because it cannot be said to be a complete countermeasure.

Third, there were disadvantages and inconveniences in terms of use and handling.

That is, while the table feed speed and the like of the machine tool are optionally selected by the user, the displacement detection device has a limit on the allowable relative movement speed of both scales 10 and 20 determined by the characteristics of the electrical equipment concerned. Therefore, there is a problem in that the response speed is limited in that if the relative movement speed is used at a high speed exceeding the allowable relative movement speed, erroneous counting will occur. Furthermore, if the power to the device is cut off due to operation on the user's side or by accident or carelessness, the cumulative count value will be lost, and the work efficiency will be lowered as the cumulative count value will be lost. there were. On the other hand, in order to avoid this, a backup power source had to be provided, which was a problem in terms of equipment economy.

Fourthly, in the optical displacement detection device, there is a problem that the power consumption of the light source 1, that is, the illumination system is extremely large.

That is, with recent advances in electronic technology, the power consumption of the signal detection circuit 7 and the like can be made very small, but regardless of the type of LED or the like, the power consumption of the light source 1 is limited by its optical energy. 1- It is at the limit, and it is extremely difficult to make it significantly smaller. This is light source 1
The power consumption for this is 7 times the power consumption of the entire displacement detection device.
This led to a situation in which the ratio ranged from 0% to 80%. Therefore, especially when using a displacement detection device as a sensor in a compact and lightweight length measuring machine, for example, the voltage of the battery that is the power source drops quickly, resulting in a deterioration of the S/N and making it difficult to guarantee measurement accuracy. The drawback was that it was impossible to measure.

On the other hand, in order to avoid these situations, increasing the capacity of the battery increases the size of the entire length measuring machine, which is not only putting the cart before the horse and going against the idea of miniaturization, but also causing the hassle of battery replacement, narrowing the usage patterns, etc. There were economic disadvantages in handling such things as stockpiling replacement batteries.

These problems are due to the fact that conventional optical displacement detection devices are incremental in their structure. There has been a strong desire to develop an optical displacement detection device that can reduce this.

(Object of the Invention) The present invention has been made in view of eliminating the above-mentioned conventional problems, and an object of the present invention is to provide an absolute type optical displacement detection device that consumes little power and can achieve high resolution and high precision detection. purpose.

[Means and effects for solving the problems] The present invention has the following features:
Two rows of optical gratings with different pinches for each row are provided on the main scale, and an optical grating with corresponding rows and corresponding pinches is also provided on the index scale. By skillfully utilizing the phase difference between the sets, it is possible to detect the absolute displacement of the relative movement of both scales over a wide range significantly larger than the pitch of the optical grating with a resolution smaller than the pitch of the optical grating. At the same time, intermittent lighting was used to reduce power consumption.

For this reason, there is a main scale in which two rows of optical gratings are provided and each row has a different optical grating pinch, and two rows of reference optical gratings corresponding to each row of optical gratings on the main scale. an index scale that is displaceable relative to the main scale; an illumination system for irradiating light onto both scales; For each set, the transmitted light transmitted through the main scale or the reflected light reflected from the main scale is received.
A plurality of sets of photoelectric converters that output electrical signals with a phase shift of 0 degrees are obtained, and an inter-set phase difference between the electrical signals output from each set of the photoelectric converters is determined, and this inter-set phase difference is utilized. and an absolute displacement detection circuit formed to be able to detect the absolute value of the relative movement displacement amount between the main scale and the index scale, and an illumination system drive circuit for driving the illumination system, and the illumination system is operated intermittently. The above objective is achieved by configuring the sensor so that it can be driven and detect absolute displacement.

Therefore, by relatively moving the main scale, which has two rows of optical gratings with different pitches, and the index scale, which has two corresponding rows of reference optical gratings with different pitches, the phase can be shifted by 90 degrees. A phase difference θ1 is detected from the photoelectric converter corresponding to the first row of two reference optical gratings.
Similarly, the photoelectric converter corresponding to the reference optical grating in the second column outputs an electrical signal having a phase difference θ2.

Here, the absolute displacement detection circuit samples and holds the electrical signal with the phase difference θ1 and the electrical signal with the phase difference θ2 at appropriate times, calculates the inter-group phase difference (θ2−θ,), and calculates the inter-group phase difference ( Using θ2−θ1), the absolute value of the relative movement amount of both scales can be determined with high resolution and accuracy.

In particular, since the illumination system is driven intermittently by the illumination drive circuit, for example, only for a predetermined period of time immediately before absolute value detection, it is not necessary to constantly drive the illumination system during relative movement of both scales, and power consumption can be dramatically reduced.

〔Example〕

An embodiment of the optical displacement detection device of the present invention will be described in detail with reference to the drawings.

This embodiment is shown in FIGS. 1 to 4, and the apparatus includes a main scale 10 provided with two rows of optical gratings, an index scale 20 provided with a corresponding reference optical grating, and both scales 10120. An illumination system 40 for irradiating light, an illumination system drive circuit 70 for intermittently driving this illumination system, and two sets (30A, 30B) of photoelectrons that receive transmitted light from both scales 10 and 20 and output electrical signals. It consists of a converter 30 and an absolute displacement detection circuit 50 that is configured to determine the phase difference between sets and detect the absolute value of the relative displacement amount of both scales 10920.

As shown in FIGS. 1 and 2, the main scale 10 has the shape of an elongated thin plate made of a glass material 11 with a rectangular cross section, and a first optical grating 13 with a pitch P of 400 μm is placed on the lower side in the figure, and a first optical grating 13 on the upper side in the figure is made of a glass material 11 with a rectangular cross section. A second optical grating 15 with a pitch P-ΔP of 398 μm is provided on the side.

Here, the first optical grating 13 has a detection range of 80 m)
is divided into N (=200) equal parts, and the second optical grating 15 is divided into N+1
Since it is formed to be equally divided, L=NP= (
N+1) (P −Δ P ) ・・・ ・
...(1) holds true. The above values were chosen for this relationship.

On the other hand, the index scale 20 is the main scale l.
A first reference optical grating 23A (corresponding to the first optical grating 13 of the main scale 10) is provided on the lower side as shown in FIG. 23B) and a second optical grating 15 on the upper side.
A second reference optical grating 25A (25B) corresponding to the second reference optical grating 25A (25B) is provided.

The pitch of the first reference optical grating 23A (23B) is q, and the pinch of the second reference optical grating 25A (25B) is q-Δq. Two sets of reference optical gratings 23A, 23B, 25A, whose phases are shifted by 90 degrees with respect to the optical gratings 13°15 of 2;
25+3 is provided. Note that in this example, q=
P, Δq−ΔP.

Next, the photoelectric converter 30 is formed from four photoelectric elements 33A, 33B, 35A, 35B forming two sets (3OA, 30B), each reference optical grating 23A, 23B, 25A,
25B and each photoelectric element 33A, 3
3B, 35A, 35B have preamplifiers 37A, 37B,
38A and 38B are connected to each other. Also, on the opposite side of the photoelectric converter 30 with both scales 10 and 20 in between, there is an L
An illumination system 40 is provided for irradiating parallel light onto both scales 10 and 20, which are composed of a light source 41 consisting of an ED and a collimator lens 42, and this illumination system 40 has a predetermined relationship with the index scale 20 and the photoelectric converter 30. It is integrally movable relative to the main scale 10 in the X direction in the figure.

Here, as shown in FIG. 2, the point T where the first optical grating 13 and the second optical grating 15 coincide is set as the origin, and the coordinates, that is, the relative position of the index scale 20 with respect to the main scale 10, are set to the right in the figure. If the moving displacement amount is X,
The photoelectric elements 33A and 33B are the first reference optical grating 23A.
, 23B with a phase difference of 90 degrees, the output of the photoelectric element 33A is
If the output of B is S, then the phase difference θ1 between the electrical signals from both optical elements 33A and 33B can be approximated as follows. Note that □ in the second term on the right side of equation (3) is introduced as a correction term because the amount of transmitted light is maximum at the origin T.

Similarly, if the outputs of the photoelectric elements 35A and 35B are a, b, respectively, the phase difference θ8 of the electric signals from the photoelectric elements 35A and 35B can be approximated as follows.

Further, the absolute displacement detection circuit 50 is triggered by a trigger output from the touch sensor 65 via the CPU 55 at the time when the relative displacement amount X of both scales 10 and 20 is to be determined.
Output signals al+bl+' of each photoelectric element 33A, 33B, 35A, 35B! A sample and hold circuit 51 for sampling and holding +b2 and the output signal al held from this sample and hold circuit 51.
. ．． The CPLJ 5 issues timely commands to the multiplexer 52 and the A/D converter 53, and also performs predetermined arithmetic processing, etc., which will be described later, based on the input data.
5, and a touch sensor 65 and a display means 60 are connected to the CPU 55 via a bus 54.

The illumination system drive circuit 70 also includes a pulse generator 71 for generating a pulse signal of a predetermined length of time, and amplifies the pulse signal into a signal sufficient to drive the LED (light source 41) forming the illumination system 40. It is formed from an amplifier 72 for. Then, the pulse generator 71 outputs an output from the absolute displacement detection circuit 50 based on a trigger output from the touch sensor 65 to specify the time point at which the relative displacement amount X of both scales 10 and 20 is to be determined. Depending on the command, the sample and hold circuit 5 changes in time as described above.
It is assumed that the motor is driven before operating the motor.

Now, in the CPU 55, as shown in FIG. 4 (B), the final result is X=X, + Δ X, = np + Δ X+
The absolute displacement IX from the origin T is determined as −(11).The vertical axis of FIG. , ΔX1 is the absolute displacement amount within the n+1st pinch P of the first optical grating 13.

In other words, the main scale 10 has two rows of optical gratings 13.1.
5 and corresponding to each optical grating 13.15, each set of photoelectric elements 35B, 35A and 33B.

The reason why the absolute method was adopted using the inter-set phase difference (θ2−θ,) with respect to 33A is as follows.

That is, the above equation (5) can be converted as follows.

P-ΔP2 ... (7) Then, by substituting equations (3) and (2) into equation (7), it becomes. Therefore, it follows from equation (8).

Therefore, in the CPU 55, from equation (9), the photoelectric element 33A corresponding to the first optical grating 13 of the main scale 10,
Phase difference θ1 of output signal al+ b+ from 33B
and photoelectric elements 35A, 35 corresponding to the second optical grating 15
Output signal a! from B! If the phase difference θ2 of +bZ is determined, the absolute displacement amount X from the origin T can be determined since the length of the detection range has been determined.

Here, θ1 and θ2 are obtained from equations (4) and (6)...
... It is required as a groan.

Furthermore, in this embodiment, in order to further stabilize the accuracy, θ1 and θ2 are not made independent, but are formed to have a correlation function to determine the absolute displacement X.

If θ2 and 01 were obtained independently and simply subtracted based on equation (9), each photoelectric element 33A, 33B, 35
Output signal dl+ bI+a,, b2 from A, 35B
is the pitch P of each optical grating 13.15.

This is because the waveform is cyclic for each P-ΔP, so there is a risk of loss of digits.

Therefore, a and b are newly defined.

By substituting equations (41, (6) into this equation aυ, a=AB
sin (θ2-01) b -A Bcos (θ2- θ l )--
-Lan(02-〇, )...
... (2) Therefore, θ2-θ+ = tan-'
□・・・・・・ As αJ, the photoelectric element 35A is calculated by calculating the arctangent function.

Phase difference between strings 35B, 33A, and 33B (θ2−θI
).

By the way, as is clear from 2Qa, the phase difference between the pairs (θ2
-θ1) changes from 0 to 2π within the detection range length as shown in Figure 4 (A), so the displacement
゛ is the neighbor value of the absolute value X shown in (B). Therefore,
Similar to equation (9) holds true.

Furthermore, as shown in Section 41a (B), the absolute relative movement amount of both scales 10.20 (i 161).

Here, formula f31. Although it is possible to determine the narrow range displacement ΔX within the pitch P of the first optical grating 13 of the main scale 10 from M, it is possible to determine the narrow range displacement ΔX of the first optical grating 13 of the main scale 10, Since the phase difference θ based on 33A and 33B is a periodic function of the pitch P, it is impossible to specify which pinch (counting from the origin 'r) it is within.

Therefore, the above-mentioned phase difference θ1 is converted into a phase difference θ1゛ whose phase is shifted by more than 1− to less than (2π+□). Then, the formula (3
), then holds true.

On the other hand, the number n of pitches P of the first optical grating 13 that has passed from the origin T to the relevant point is determined by
It is clear that the number does not exceed , and it is an integer.

However, as an exception, in Figure 4, the measurement resolution Δ
In the case where L is the same as (B) and includes a region where the phase changes to 2π-0, ΔX may be 0 from 2π and 1 may be added to the integer.

Here, as shown in 2〇〇, I was asked to do it.

Therefore, it can be determined as a function of n=f (θ2-θ4.ΔXt).

From the above, in cpus s, X of the formula α0 = np + ΔX
By calculating [, the absolute value X of the relative displacement amount of both scales 10°20 can be obtained.

Next, the operation of this embodiment will be explained.

For example, main scale 1 is installed on a stationary object such as a machine tool vent.
0 is fixed, the index scale 20 is integrated with the illumination system 40 and the photoelectric converter 30, and the index scale 20 is fixed to a movable body such as a slider. Therefore, by operating the machine tool,
A touch sensor 65 that allows the main scale IO and the index scale 20 to move relative to each other and outputs an output at a predetermined time.
When the illumination system drive circuit 70 is driven based on a command from the absolute displacement detection circuit 50 by a trigger from the .

33B, 35A, and 35B output electrical signals a, , b, laZ + b, which are approximately sine waves and approximately cosine waves, and signals al+ bl and a! + The cycle differs from bR by an amount equivalent to the pitch difference of the optical grating 13.15,
and signal a1, and a2 and b2 are each 90
This produces a phase difference of degrees.

That is, as shown in Figure 3, both scales are 13.15.
When a trigger is input from the sensor 65 that operates when the absolute value of the relative displacement amount is to be displayed on the display means 60 or output as a feedbank signal to the control device (not shown) (step 10), the above-mentioned Lighting drive circuit 7
After instructing to drive 0, a hold command is issued from the CPU 55 to the sample hold circuit 51 via the control data bus 54.

The sample hold circuit 51 is a preamplifier 37A.

Analog electrical signals a l + bl and 22+ bl are held from the output stages of 37B, 38A, and 38B (step 12).

Then, as in step 14, the multiplexer 52
Electrical signals a1, bl and a based on commands from U55
m+b2 is taken in, converted into a digital signal by the A/D converter 53, and then input to the CPU 55.

Hereinafter, the CPU 55 selects the photoelectric element 33A corresponding to the first optical grating 13 based on the formula 〇〇 and α9.

The phase difference θ1 from 33B and the narrow range displacement amount ΔXt are calculated (step 16). That is, the first optical grating 13
The amount of displacement within the pinch P is determined as an absolute value. Of course, in order to specify whether the phase difference θ1 is within any pitch, θ1 is a value of □ or more to (2π10□) or less.
It is converted into `` within the CFU 55.

Also, in step 18, 8011. +12) and the inter-group phase difference θ2- based on the phase difference between these and the photoelectric elements 35A, 35B and 33A, 33B.
A tangent function with θ1 is determined, and an arctangent function is calculated to calculate the inter-set phase difference θ2−θ1.

Here, the number n of pitches P of the first optical grating 13 that have passed so far, which corresponds to FIG. 4, is determined based on n=f (θ2-01.ΔX,) (step 20).

Therefore, in step 22, the absolute value X of the relative displacement position of both scales 10 and 20 is determined by calculating 2 Oe. This absolute value X is displayed on the display means 60,
Output to the outside as necessary. Here, the absolute displacement amount at a desired time point specified by the touch sensor 65 can be detected and displayed.

In this embodiment, the pitch P of the first optical grating 13 of the main scale 10 is 400 μm1 The relationship between the first optical grating 13 and the second optical grating 15 is the detection range length L = 8
Since it is defined as On+ and N=200, the absolute value can be detected within the detection range length L (=8ON) with a resolution of 2 μm.

Therefore, according to this embodiment, the main scale 10 has two rows of optical gratings 13 with different pitches P and P-ΔP.
．． 15 is provided, and the main scale 10 and the index scale 20 are separated within the detection range length using the phase difference (θ2-θ1) between the sets obtained from the relationship with these optical gratings 13 and 15.
It is possible to detect the amount of displacement relative to the object as an absolute value. Since an absolute type optical displacement detection device can be established here, industrial applicability can be dramatically expanded in terms of accuracy and operational technology.

This ensures stable predetermined accuracy because there is no influence of noise on the way and there is no accumulation of noise, and since continuous tracking is not required, response speed is high and rapid measurement can be achieved. This means that even if the power is cut off, it is possible to immediately re-measure without having to adjust the origin each time, thereby eliminating the drawbacks, disadvantages, and inconveniences of the conventional incremental method.

In addition, two rows of optical gratings 13 provided on the main scale 1o
．． No. 15 is physically fixed on a glass plate by an edging method or the like, and is made by utilizing the inter-set phase difference between optical gratings with different pitches and the phase difference within the same optical grating. Since it is designed to detect the absolute value of the amount of displacement, for example, unlike the conventional incremental system in which the waveform generated within one pinch is electrically subdivided by resistance division, both scales are 10.20. In other words, it is possible to ensure true high-precision measurement while being compatible with the machine tool used.

Furthermore, in order to obtain the phase difference between the two optical gratings 13.15, the phase difference between the two optical gratings 13. Detection without loss of precision can be achieved by making the correlation between High accuracy is guaranteed from this point as well.

In particular, in this embodiment, the illumination system drive circuit 70 is configured to be driven for a predetermined period of time based on the trigger of the touch sensor 65 for specifying the time point at which absolute displacement is detected. Since the illumination system 40 only needs to be driven for an extremely short period of time sufficient for the response, power consumption can be significantly reduced. This means that when a battery is used as the driving power source for the displacement detection device, the capacity of the battery can be reduced, which is beneficial for reducing the overall size and weight, as well as reducing the S/N within a short time. This has an excellent practical effect in that it can avoid situations in which detection becomes undetectable.

In this embodiment, the pitch P of the first optical grating 13 of the main scale 10 is 400 μm, and the pitch P of the second optical grating 1 is 400 μm.
The pitch P-ΔP of 5 is 398 μm, and the number of divisions N is 200 within a detection range length of 80 fi so that detection can be performed with a resolution of 2 μm, but these numerical matters can be selected arbitrarily. with a resolution of 0.1 μm
The following can also be used. Similarly, the pitch q of the reference optical gratings 35A and 35B of the index scale 20 is the same as the pinch of the first optical grating 13 of the main scale 10, but the pinch is set to 1/n( The present invention is also applied when n is an integer of 1 or more, and in this case, the optical grating 13 of the main scale 10
．． The resolution can be increased without making any modification to 15. Also,
Each reference optical grating 23A.

23B, 25A, and 25B were formed from two pieces each with a phase shift of 90 degrees, but the point is that if a phase difference can be created in the relationship with the optical grating 13.15 of the corresponding main scale 10, the pitch q can be slightly changed. It is also possible to form one each by employing different so-called vernier reference optical gratings. Furthermore, if the two output electrical signals from the photoelectric element, which are phase-shifted by 90 degrees, are subdivided, for example, by a differential method, the dynamic range (detection range/resolution) can be improved.

In addition, although the detection device itself is a transmission type using an illumination system that emits parallel light, it may also be a reflection type as shown in Figure 5, or it may be a rotary type as shown in Figure 6 instead of a linear type. The invention is applicable. The reflective type shown in FIG. 5 includes a main scale 10 provided with two rows of optical gratings 13.15, a second scale placed in front of the main scale 10 (optical gratings 13.15), and a second scale placed after the main scale 10 (optical gratings 13.15) on the optical system. The index scale 20 (reference optical grating 23
(A, B), 25 (A, B)') are disposed facing each other so as to be relatively displaceable, and both scales 10.20 are non-parallel for irradiating diffused light or light containing diffused light, that is, non-parallel light. An illumination system 40 is provided, and a half mirror 45 is installed between the non-parallel illumination system 40 and the index scale 20,
With main scale 10 and index scale 20
The amount of reflected light irradiated through the index scale 2
The electric signal received by the optical element 33.35 through the 0° half mirror 45 and photoelectrically converted is processed in a predetermined manner by the absolute displacement detection circuit 50 as in the above embodiment, and is then output to both scales 10.
．． This is an attempt to find the absolute amount of the relative displacement amount of 20.

Therefore, according to the displacement detection device shown in FIG.
Since the clearance C between 20 can be increased, processing, assembly, and adjustment can be facilitated, and stable operation can be ensured.

In addition, in the rotary type shown in FIG. 6, the main scale 10 is provided with two rows of optical gratings 13 and 15 along the circumference of a rotating disk 11 fixed to a rotating shaft 6, and an arcuate index plate 21. Two corresponding rows of reference optical gratings 23A, 23B,
25A and 25B are provided to determine the absolute amount of relative rotational displacement of both scales 10 and 20. In other respects, there is no difference from the case of the first embodiment. Therefore ζ
According to the rotary type shown in FIG. 6, the amount of absolute displacement can be determined as rotational displacement. In this way, the present invention provides two rows of optical gratings to form an absolute type, and since it is sufficient to drive the illumination system 40 intermittently, it is possible to use transmission type/reflection type, parallel light illumination system/non-parallel light illumination system, linear type, rotary type, etc. This means that it can be implemented without any restrictions.

Further, although the touch sensor 65 is used to identify the time of displacement detection, the present invention is not limited to this. Further, it is also possible to enable the absolute displacement detection circuit 50 to detect displacement at every fixed sampling time.

Furthermore, in the case of the above embodiment, the detection range length is the length in the direction of relative movement between the main scale 10 and the index scale 20, but this detection device detects displacement and the measurement target is lengthened. It is not limited to height, width, etc., but may also be angle, speed, pressure, weight, etc.

Of course, compared to the case where the absolute method is implemented using a binary code or Gray code for the scale, in the case of the present invention, the number of grid columns is significantly smaller.
It is understood that the pitch can be made narrower and the detection range (detection range/resolution) is higher, making a significant difference in practical value. Furthermore, it is easy to count the passing points of a detection range length and perform extended detection over a plurality of detection range lengths.

[Effects of the Invention] The present invention has the advantage that it is possible to provide an optical displacement detection device of the Abflu 1 type, which has low power consumption and can achieve high resolution and high precision displacement detection.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram showing an embodiment of the optical displacement detection device according to the present invention, FIG. 2 is an enlarged view of the main parts, and FIG. 3 is a flowchart for calculating the absolute displacement amount. 4 is a waveform explanatory diagram, FIG. 5 is a schematic diagram of a reflective type similarly showing another embodiment, FIG. 6 is a schematic diagram of a rotary type similarly showing another embodiment, and FIG. 7 is a schematic diagram of a conventional optical system. 1 is a schematic configuration diagram of a displacement detection device according to the present invention. DESCRIPTION OF SYMBOLS 10... Main scale, 13... First optical grating, 15... Second optical grating, 20... Index scale, 23... First reference optical grating, 25...
Second reference optical grating, 30...Photoelectric converter, 40...
- Illumination system, 50... Absolute displacement detection circuit, 70... Illumination system drive circuit.

Claims (2)

[Claims] (1) A main scale provided with two rows of optical gratings and each row having a different optical grating pitch, and two rows of reference optical gratings corresponding to each row of optical gratings of the main scale. an index scale disposed and movable relative to the main scale; an illumination system for irradiating light to both scales; Each time, the transmitted light transmitted through the main scale or the reflected light reflected from the main scale is received.
Two sets of photoelectric converters that output electrical signals with a phase shift of 0 degrees, and the inter-set phase difference between the electrical signals output from each set of the photoelectric converters are determined, and this inter-set phase difference is utilized. and an absolute displacement detection circuit formed to be able to detect the absolute value of the relative movement displacement amount between the main scale and the index scale, and an illumination system drive circuit for driving the illumination system, and the illumination system is operated intermittently. 1. An optical displacement detection device characterized in that it is configured to be able to detect absolute displacement by driving the device. (2) In claim 1, the illumination system drive circuit includes a pulse generator for driving the illumination system for a predetermined time based on a command from the absolute displacement detection circuit. An optical displacement detection device characterized by: