JPS61118606A - Optical dimension measuring machine - Google Patents

Abstract

PURPOSE:To perform highly accurate measurement at a high speed, by subtracting the value, which is obtained by multiplying the relative moving speed of an object to be measured and a photoelectric sensor by the detection delay time of the edge signal of the object to be measured, from a detection displacement amount to eliminate the time delay of the output of the sensor. CONSTITUTION:The projection image 4A of an object 4 to be measured on a mount stand 3 is detected by light receiving elements 12A, 12B and convered by photoelectric converters 32A, 32B to calculate S-shaped signals (a), (b) equal in amplitude and shifted in a phase. The signals (a), (b) are processed by the differential operator 24, filter 30, detection means 28 and region comparator 26 in an edge detection circuit 14 to output a signal (g). The displacement of the object 4 to be measured is detected by a detector 46 to be inputted to a counter 48. The counter 48 sends a displacement amount to a correction circuit 22 every when the signal (g) is inputted. The displacement amount from the counter 48 is corrected by the speed signal detected from the output of an encoder 46 by a speed detection means 18 and the output of a time setting device 20 and stored in a memory apparatus 50 to be displayed. By this method, the time delay of the output of a sensor is corrected to perform highly accurate measurement at a high speed.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an optical dimension measuring machine for measuring the dimensions, displacement, etc. of an object, and particularly relates to an optical dimension measuring machine that directly irradiates the object to be measured with a scanning light beam and generates transmitted or reflected light, or This article relates to an improvement of an optical dimension measuring machine for making a photoelectric sensor receive a projected image of an object to be measured by light or reflected light, extracting an electrical signal, and measuring the dimensions of the object based on this signal.

[Conventional technology]

Conventionally, this type of optical dimension measuring equipment, for example, a projector, illuminates the object to be measured on a stage with parallel light beams, and projects a projected image of the object on a screen based on the transmitted light or reflected light. The size and shape of the object to be measured are measured from this image, but the edges of the image of the object to be measured that are projected onto the screen generally have so-called blur, and therefore It is difficult to move the object to be measured on the stage and read the measured value accurately from the coincidence of the image formed on the screen and the hairline. In order to solve this problem, conventionally, by moving the edge of the image and the photoelectric sensor relative to each other, the photoelectric sensor is detected based on the change in the area ratio between the bright and dark areas of the image projected on the light receiving surface of the photoelectric sensor. Some devices detect the edge of a projected image by comparing changes in the magnitude of an S-curve analog signal output from a sensor with a reference voltage. That is, a photoelectric sensor that is movable relative to the image of the object to be measured and that optically captures the image of the object to be measured and generates an S-curve-shaped analog signal at the edge thereof; and an output of the photoelectric sensor. an edge detection circuit that detects the intersection between the analog signal of the object and a preset reference signal and outputs an edge signal of the image of the object to be measured; and a displacement detector that detects the amount of relative displacement between the object to be measured and the photoelectric sensor. There is a device which measures the dimensions of the object to be measured from the amount of relative displacement between the object to be measured and the photoelectric sensor while the edge signal is generated. Here, in the edge detection circuit, in order to avoid the influence of noise generated from peripheral equipment, etc., a cross-point detection circuit for detecting the intersection of the analog signal of the photoelectric sensor output and a preset reference signal is used. A filter is inserted in the reference signal to prevent it from becoming impossible to identify the intersection due to noise generated near the reference signal. However, when a filter is provided in this way, a time delay occurs in the detection signal relative to the position of the photoelectric sensor. For example, when the object to be measured moves at 20u/5 (20μIl/μS), there is a time delay of several μs. occurs, making measurement with an accuracy of 1 μI impossible. Furthermore, in recent years, high-precision measurement and high-speed feeding have been required for this type of optical dimension measuring machine, and in this case, a filter that aims to improve measurement accuracy by eliminating noise is required to There is a problem in that the time lag has become a factor in reducing measurement accuracy. Conventionally, this problem has been conventionally solved by increasing the projection magnification in projectors, but this also has its limitations.

[Problems/points to be solved by the invention]

The present invention was made in view of the above problems, and an object of the present invention is to provide an optical dimension measuring machine that can perform accurate measurements by correcting the time lag caused by the filter for eliminating noise. do.

[Means to solve the problem]

The present invention relates to a photoelectric sensor that is movable relative to the object to be measured and that optically captures an image of the object to be measured and generates an S-curve-shaped analog signal at an edge portion of the image; an edge detection circuit that detects the intersection of the output analog signal and a preset reference signal and outputs an edge signal of the image of the object to be measured; and a displacement that detects the amount of relative displacement between the object to be measured and the photoelectric sensor. an optical dimension measuring machine that measures the dimensions of the object from the amount of relative displacement between the object and the photoelectric sensor while the edge signal is being generated; speed detection means for detecting the relative movement speed of the photoelectric sensor; a time setting device for setting the detection delay time of the edge signal; and a displacement amount detected by the displacement detection device when the edge signal is generated. The above object is achieved by comprising: a correction circuit that corrects the detected displacement amount by subtracting the product of the relative movement speed and the set time. Further, the above object is achieved by using the speed detection means to detect the relative movement speed immediately before the edge signal is generated from the edge detection circuit. Further, the above object is achieved by using the speed detecting means to detect the relative moving speed by time-managing the pulsed signal output from the displacement detecting device. Further, the above object is achieved by using the speed detecting means to detect the relative movement speed by differentiating the analog signal output from the photoelectric sensor. Further, the above object is achieved by making the setting time of the time setting device variable.

[Effect]

In this invention, the detected displacement amount is corrected based on the relative movement speed of the photoelectric sensor with respect to the image of the object to be measured, thereby preventing measurement errors due to time lag and improving measurement accuracy.

【Example】

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, the present invention is applied to a projector, and as shown in FIGS. 1 to 4, a light source lamp 1 is used.
from below the stage 3 through the condenser lens 2, or from above the stage 3 through another optical path.
The object to be measured 4 on the stage 3 is irradiated, and based on the transmitted light or reflected light, it is projected onto the screen 6 through the projection lens 5.
A projector 10 is configured to form a projected image 4A of the object to be measured 4 on top of the object to be measured, and indirectly measure the dimensions of the object to be measured 4 using the projected image 4A. Projected image 4 of the measurement object 4, which is relatively movable by
A photoelectric sensor 2 that optically captures A and generates an S-curve-shaped analog signal at its error margin, and detects the intersection of the analog signal output from the photoelectric sensor 2 and a preset reference signal. Projection image 4A
an edge detection circuit 14 that outputs an edge signal, and a displacement detection device 16 that detects the amount of relative displacement between the measurement target 4 and the photoelectric sensor 12, and the measurement target while the edge signal is generated. In the projector 10, the dimensions of the object to be measured 4 are measured from the amount of relative movement displacement between the object to be measured 4 and the photoelectric sensor 12; a time setting device 20 for setting the detection delay time of the edge signal; and the displacement detection device 1 during which the edge signal is generated.
A correction circuit 22 that corrects the detected displacement amount by subtracting the product of the relative movement speed and the set time from the detected displacement position according to No. 6 is provided. The photoelectric sensor 12 generates an S-curve phase shift signal a based on the brightness that occurs when moving relative to the projected image 4A.
, b, and includes two light receiving elements 12A and 12B arranged concentrically in a plane substantially parallel to the movement plane, and sensor output signals a, based on the outputs of both light receiving elements 12A and 12B.
The level at the sensor output terminals 13A and 13B of b is
It is formed to have the same value in each of the bright and dark states that occur during the relative movement. The edge detection circuit 14 is connected to the sensor output terminals 13A and 13B of the photoelectric sensor 12, and includes a difference calculator 24 that calculates the difference between the phase shift signals a and b, and an output signal a of the photoelectric sensor 12, A region signal generator 26 receives one signal a of signal b as an input signal and outputs a signal e in a specific region including the intersection of the phase-shifted signal with the reference signal, and a signal is output from the region signal generator 26. Between,
It includes a detection means 28 that outputs a cross signal g, that is, an edge signal at the intersection of the output signal of the difference calculator 24 and a preset reference signal, and a filter 30 between the difference calculator 24 and the detection means 28. I'm here. Further, between the edge detection circuit 14 and the photoelectric sensor 12, there are current-voltage converters 32A and 32B for exchanging the outputs of the light receiving elements 12A and 12B into voltage signals.
is located. As shown in FIG. 1, the photoelectric sensor 12 is provided integrally with a transparent plate 33 that is slidably placed on the upper surface of the screen 6 of the projection 1110 in parallel thereto. It is also possible to move with it. The light receiving element 12A constituting the photoelectric sensor 12 is formed to have a circular cross section, and the light receiving element 12B is similar to the light receiving element 1.
2A, the light receiving elements 12A are spaced apart in the radial direction.
It is formed into a concentric ring shape. The area signal generator 26 compares one signal a of the sensor output signals with a first reference signal V ref+, and generates a signal 0 when the one signal a is smaller than the first reference signal V ref+. A first comparator 34 that outputs, and a second comparison that compares the one signal and the second reference signal Vref- and outputs a signal d when the one signal is smaller than the second reference signal. 36 and the first and second comparators 3
When only one of 4 and 36 outputs a signal, the area signal e
An exclusive OR gate 38 that generates . The detection means 28 also includes a comparator 40 that compares the output signal of the difference calculator 24 with a reference signal and outputs a signal when the two match, that is, at a cross point; is output, a pulse signal generator 42 generates an edge pulse signal based on this.
And this pulse signal generator 42 and the above! ! The AND gate 44 outputs the edge signal g only when signals are output from both of the i-band signal generators 26. The displacement detection device includes an encoder 46 for detecting the amount of movement of the document table 3, and counts the output of the encoder 46, and detects the object to be measured when the edge signal from the edge detection circuit 14 is input. The counter 48 outputs a signal at position No. 4. The speed detecting means 18 detects the moving speed of the stage 3 and the object to be measured 4 based on the output signal of the encoder 46 in the displacement detecting device 16, that is, the photoelectric sensor 1 which is stationary.
2 and detects the relative movement speed with respect to the correction circuit 22.
It is designed to output to . This correction circuit 22 receives the output signals of the speed detecting means 18, the counter 48, and the time setting device 2o, corrects the position signal from the counter 48, and stores it in the storage device 50.
It is designed to output to . Here, the output signal of the time setter 20 is uniquely determined by the delay constant in the edge detection circuit 14, mainly by the characteristics of the filter 30. Next, the operation of the above embodiment will be explained. Projection image 4 of the measurement object 4 formed on the screen 6
The photoelectric sensor 12 is moved in one direction relative to A so that the edge of the projected image 4A crosses the photoelectric sensor 12. When the projected image 4A approaches the photoelectric sensor 12 and passes through it, it is obtained by the light receiving elements 12A and 12B, and is generated from the sensor output terminal 13A and 113B via the current-voltage converters 32A and 32B. The output signal becomes an S-curve-shaped phase-shifted signal with equal amplitude, as shown by symbols a and b in FIG. 3(A). As shown in FIG. 3(B), these output signals are computed into a-b by the difference computing unit 24 and output. The signal output by the difference calculator 24 passes through the filter 30 and is input to the comparator 40 of the detection means 28, and this comparator 40 outputs the output signal a as shown in FIG. 3(B).
When -b crosses the reference signal of O, a digital signal of 1 is output. Based on the output of the comparator 40, the pulse signal generator 42:
A pulse signal f as shown in FIG. 3(C) is output to the AND gate 44. On the other hand, the output signal a from the sensor output terminal 13A is
first and second comparators 34 of said area signal generator 26;
36 respectively. As shown in FIG. 4, the first comparator 34 compares the reference voltage V ref+ with the input signal a, and when the signal a is smaller than ref+, outputs a signal to the task-intensive OR gate 38. do. Further, the second comparator 3
6 compares the input signal a and Vrer-, and excludes the signal when the signal a is smaller than Vref-.
It outputs to the sibu OR gate 38. When a signal is output from only one of the first comparator 34 and the second comparator 36, the exclusive OR gate 38 is set to 1 as shown in FIGS. 3(D) and 4. outputs a digital signal e. The pulse signal f from the pulse signal generator 42 and the digital signal e from the exclusive OR gate 38 are
When both input signals are 1, the AND gate 44 outputs an edge signal (pulse signal) of, for example, 10 μs as shown in FIG. 3(E).
Q is output, and at this point, edges of the projected image l14A are detected. On the other hand, the encoder 46 in the displacement detection device 16 detects the amount of movement of the stage 3, and the counter 48 counts the output signal of the encoder 46 and outputs an absolute position signal at each time. The edge signal g from the AND gate 44 in the detection means 28 is applied to the counter 48 in the displacement detection device 16.
The counter 48 calculates the amount of displacement counted when the edge signal 0 is input, that is, the amount of displacement of the object to be measured 4.
The position signal is output to the correction circuit 22. This correction circuit 22 corrects the signal from the counter 48 in accordance with the moving speed of the measurement object 4 based on the output signals of the speed detection means 18 and the time setting device 20, and outputs the signal to the storage device [50]. do. That is, from the detected displacement meter of the displacement detecting device [16 fixed by the edge signal g], the edge detecting circuit 14
The delay time t of the analog signal, which is determined by a constant mainly based on the characteristics of the filter 30, and the measurement target 4
The detected displacement is corrected to L-ΔL by subtracting the length ΔL, which is the product of the velocity V of
The output signal from the storage device @50 is displayed on a display or output to a printer. Therefore, in this embodiment, the amount of displacement of the measurement object 4 detected by the displacement detection device 16 is determined by the correction circuit 22.
Therefore, even if the filter 30 is provided in the edge detection circuit 14, the time delay of the detection signal with respect to the actual position with respect to the projected image 4A of the photoelectric sensor 12 can be eliminated, and high-speed, high-precision measurement can be performed. I can do it. Further, in this embodiment, the light receiving elements 12A and 12B constituting the photoelectric sensor 12 are formed in a concentric shape, and the sensor output terminals 13A and 13B generated by these elements
Since the output levels of the signals are made equal, the moving direction of the photoelectric sensor 12 does not coincide with the boundary line of the light receiving elements 14A and 14B, and the relative moving force with respect to the projected image 1) 4A of the photoelectric sensor 12. Regardless of the direction, a uniform output signal can be obtained, and therefore there is no restriction on the relative movement direction of the photoelectric sensor with respect to the object to be measured, and edge detection can be performed with high precision. Further, as described above, since the light receiving elements 12A and 12B constituting the photoelectric sensor 12 are configured in a concentric circle, the area of the light receiving surfaces of the light receiving elements 12A and 12B facing the object to be measured can be reduced. Therefore, it is not only applicable to small measuring instruments, but also simplifies the supporting means, and
In a projector, the effective viewing range of the screen can be increased. Furthermore, since the photoelectric sensor 12 is small, it can also be applied to edge detection of a complex-shaped object to be measured. In the above embodiment, the speed detection means 18 detects the speed of the object to be measured 4 at each point in time of the pulse signal output from the encoder 46, and outputs this to the correction circuit 22, which performs the correction. Although the circuit 22 corrects the output of the counter 48 based on the moving speed immediately before the edge signal from the edge detection circuit 14 is generated, the present invention is not limited to this; The speed signal output from the detection means 18 to the correction circuit 22 is
It may be the average relative movement speed for a certain period of time immediately before the edge signal from the edge detection circuit 14 is generated. In this case, the influence of output errors in the encoder 46 can be prevented. However, when the correction circuit 22 corrects the detected displacement amount based on the relative movement speed immediately before the edge detection signal is generated, there is an advantage that more accurate correction can be performed. Further, in the above embodiment, the speed detection means 18 is replaced by the encoder 46.
The moving speed of the object to be measured 4 is detected based on the output of , a sensor similar to the photoelectric sensor 12,
A detection device similar to the displacement detection device 16 may be separately provided to detect the speed.
The speed may be detected by differentiating the analog signal of No. 4. Further, the time setting device 20 is configured to set the detection delay time t based on the characteristics of the filter 30, but this may correspond to constants of other elements or even actual numerical values in the manner of use. Therefore, it is better to use a variable type. Further, in the above embodiment, the light receiving element 12A is formed in a circular shape, and the light receiving element 12B is formed in a concentric ring shape surrounding the circular light receiving element 12A at a certain interval, so that a pair of S-curve phase shift signals a and b are obtained. However, the present invention is not limited to this, and the light receiving element constituting the sensor may be of any type as long as it can obtain an S-curve shaped analog signal. It may be a single light-receiving element, a combination of an optical fiber and a light-receiving element, or a combination of three or more light-receiving elements. In the above embodiment, the region signal generator 26 also includes two comparators 34 and 36 and an exclusive OR gate 38.
However, this region signal generator is not limited to the configuration of the embodiment as long as it detects the rise or fall of one of the output signals from the photoelectric sensor. In the above embodiment,
The light receiving elements 12A and 12B have equal light receiving areas so that the sensor output terminals 13A and 13B are equal.
It is sufficient that the output signals at 3A and 13B are at the same level. Therefore, an amplifier may be placed between the light receiving elements 12A, 12B and the sensor output terminals 13A, 13B, or both signals may be outputted without providing an amplifier. Sensor output terminal 1
The output levels of 3A and 113B may be made equal. Furthermore, in the embodiment described above, the sensor 7 is moved relative to the projected image 4A, but this also applies if the projection side 1114A is moved relative to the sensor 7 by, for example, moving the stage 3. good. Further, although the above embodiment is for measuring the edge of a projected image on a screen of a projector, the present invention is not limited to this, and the present invention is not limited to this, but can be performed by detecting transmitted light or reflected light, It is generally applied to optical dimension measuring machines for directly or indirectly measuring the dimensions of objects to be measured.

【Effect of the invention】

Since the present invention is configured as described above, it is possible to eliminate the time delay of the detection signal with respect to the actual position of the photoelectric sensor with respect to the object to be measured, and to perform high-speed, high-precision dimension measurement. have an effect.

[Brief explanation of the drawing]

Fig. 1 is an optical system diagram showing an embodiment in which the optical dimension measuring machine according to the present invention is implemented in a projector, Fig. 2 is a block diagram showing the configuration of the embodiment, and Fig. 3 is the embodiment. FIG. 4 is a diagram showing the signal processing process in the area signal generator of the same embodiment. 4...Measurement object, 4A...Projected image, 1
0... Projector, 12... Photoelectric sensor, 1
2A, 12B... Light receiving element, 13A, 13B... Sensor output terminal, 14... Edge detection circuit, 16... Displacement detection device, 18... Speed detection means, 20... Time setting device , 22... Correction circuit, 24... Difference calculator, 28... Detection means, 30... Filter. Agents Keisuke Matsuyama, Takaya
Figure 3 Figure 4

Claims (5)

[Claims] (1) A photoelectric sensor that is movable relative to the object to be measured and that optically captures the image of the object to be measured and generates an S-curve-shaped analog signal at its edge, and the output of the photoelectric sensor. an edge detection circuit that detects the intersection between the analog signal of the object and a preset reference signal and outputs an edge signal of the image of the object to be measured; and a displacement detector that detects the amount of relative displacement between the object to be measured and the photoelectric sensor. an optical dimension measuring machine that measures the dimensions of the object from the amount of relative displacement between the object and the photoelectric sensor while the edge signal is being generated, the object to be measured and a speed detection means for detecting the relative movement speed of the photoelectric sensor; a time setting device for setting the detection delay time of the edge signal; and a displacement amount detected by the displacement detection device when the edge signal is generated. An optical dimension measuring machine comprising: a correction circuit that corrects the detected displacement amount by subtracting the product of the relative movement speed and the set time. (2) The optical dimension measuring machine according to claim 1, wherein the speed detection means detects a relative movement speed immediately before the edge signal is generated from the edge detection circuit. (3) The optical dimension measurement according to claim 1, wherein the speed detection means detects the relative movement speed by time-managing the pulsed signal output from the displacement detection device. Machine. (4) The optical dimension measuring machine according to claim 1, wherein the speed detecting means detects the relative movement speed by differentiating the analog signal output from the photoelectric sensor. (5) The optical dimension measuring machine according to claim 1, wherein the setting time of the time setting device is variable.