JPH0257643B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to an optical measuring device, particularly an object to be measured by irradiating a parallel scanning measurement light onto the object to be measured and measuring the amount of light received at both end faces of the object. The present invention relates to an improvement of an optical measuring device that detects both end faces and measures the dimensions of a workpiece based on the scanning time between the end faces.

[Prior Art] A desired object to be measured is scanned using parallel light beams, such as a laser beam, and while detecting light transmission and light blocking due to the shape of the object, the scanning time of the parallel light beam between both end faces is adjusted, for example. Optical measuring devices that measure by counting clock pulses are well known and have been put into practical use, for example, as laser micrometers.

This type of optical measurement device allows precise measurements to be made without applying any measurement pressure to the object to be measured and without deformation or other effects, especially when measuring soft or high temperature objects. It is possible to provide an extremely effective measuring device for objects. Additionally, this type of device can measure a desired part of the object regardless of its shape, and is extremely useful for measuring materials with complex shapes.

Conventionally, this type of optical measuring device has been disclosed in Japanese Patent Application Laid-Open No. 58-205803, in which the measuring range can be divided into desired segments and precise measurements can be quickly performed for each segment.

[Problems to be Solved by the Invention] However, in conventional devices, unexpected refraction or scattering occurs in the parallel scanning measurement light due to the end face shape or surface condition of the object to be measured, or However, there is a drawback in that various types of unexpected light transmission or scattering occur during the scanning process, resulting in large measurement errors.

In particular, a typical optical measuring device is configured to count clock pulses that are synchronized with parallel measurement light while it is scanning, and obtain a measurement value based on the number of clock pulses between both end faces. For example, if refracted light is received due to a foreign object attached to the surface, or if partially transmitted light is received from a transparent object to be measured, the counting of clock pulses started after the measurement light detects one end face is correct. The refraction is terminated by the refracted light detected significantly earlier than the end face detection of the
This method had the disadvantage of causing a significantly large measurement error.
Such measurement errors have the drawback of causing almost unpredictable errors due to the surface condition of the object to be measured or irregular light transmission through the transparent object.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to reliably prevent measurement errors caused by refracted light and others that are likely to occur at the end face of a transparent part of an object to be measured, and to remove light from a light-transmitting material. An object of the present invention is to provide an improved optical measuring device that can perform accurate measurements even on objects to be measured or in poor surface conditions due to oil adhesion.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a parallel scanning measurement light that exists between both end positions, that is, between the start end and the end end, when the parallel scanning measurement light passes through the object to be measured. When a false detection signal is generated from a scratch, etc., an inverting circuit is provided that outputs an inverted signal in a predetermined corresponding relationship to both the correct detection signal and the false detection signal. A pair of counters are provided to measure the clock pulses as they pass, and these counters are driven alternately by the inversion signal, and registers are provided corresponding to each of the counters, and the count contents of the counters are determined based on the inversion timing. By this, the clock pulses when the measurement light passes through the object to be measured are always counted by one of the counters.
In addition, after the measurement light passes through the end of the object to be measured, the inverted signal is no longer output, so subsequent counted values are not latched into the register.
This method takes advantage of the fact that at the end of one scan, the total value of both registers corresponds to the length of both ends of the object to be measured, and as a result, the unnecessary count value counted by the counter is latched by the reversal timing. It is characterized in that a desired measured value can be obtained by discarding the signal by not supplying it, leaving only the necessary counted values, and summing them.

In particular, according to the invention, clock pulses are counted in either counter in a complementary manner, so that latching from one counter to the corresponding register occurs during the counting period of the other counter; As a result, there is no problem with the time delay at the time of latching from the counter to the register.According to the present invention, with such a complementary counter and register configuration, it is possible to prevent spurious signals during measurement coating. It becomes possible to carry out extremely accurate measurement operations without generating large errors even when such occurrences occur.

[Embodiment] FIG. 1 shows a preferred embodiment of the optical measuring device according to the present invention.

The object to be measured 10 is placed on a work table (not shown) and is placed within the irradiation range of the measurement light, but in the present invention, the object to be measured 10 can also be a moving object. In this case, the relationship with the irradiation light is controlled so that the object to be measured 10 is positioned within the irradiation range of the measurement light at a desired movement timing. The object to be measured 10 shown in the example is shown as a transparent cylinder.

A light scanning unit 12 is provided to irradiate the object to be measured 10 with parallel scanning measurement light 100, and the light scanning unit 12 includes a laser oscillator 14, a fixed mirror 1
6 and a rotating mirror 18, the laser oscillator 14
The laser beam 102 output from the collimator lens 2 passes through a fixed mirror 16 and a rotating mirror 18.
0, and is irradiated from the collimator 20 toward the object to be measured 10 as parallel scanning measurement light 100.

The rotation of the rotating mirror 18 is controlled by a synchronous motor 21, and the rotation speed of the rotating mirror 18 is controlled in synchronization with a clock pulse for measurement to be described later, and in the embodiment, it is the output of a clock pulse generator 22. The clock pulses are output to the synchronous motor 21 via the frequency divider circuit 24. Therefore, the scanning timing of the parallel measurement light 100 is synchronized with the clock pulse, making it possible to maintain good measurement accuracy.

The parallel scanning measurement light 100 that is the output of the optical scanning section 12 described above has a single scanning range determined in the embodiment, but in the present invention, the parallel scanning measurement light 100 is divided into a plurality of segments through a predetermined slit. However, it is also possible to perform measurements for each segment.

The parallel scanning measurement light 100 described above is applied to the object to be measured 10.
After irradiating the light, the change in brightness is detected as an electrical signal by the light detection unit 26, and the light detection unit 26 in the embodiment includes a condenser lens 28,
8, the light receiving element 30 outputs a bright signal when the parallel scanning measurement light 100 is not blocked by the object to be measured 10, and the light receiving element 30 outputs a bright signal when the parallel scanning measurement light 100 is not blocked by the object to be measured 10. In this state, the light receiving element 30 outputs a dark signal.

Therefore, if the parallel scanning measurement light 100 described above correctly detects both end surfaces of the object to be measured 10, the light detection unit 26 will output two signals corresponding to the positions of both ends of the object to be measured 10.
A pulse signal of 100 is output, and this is
The distance between the end faces can be accurately measured by measuring the scanning time between signal outputs by clock pulse counting using clock pulses synchronized with parallel scanning.

A counter is provided to measure the clock pulses, and the output of the clock pulse generator 22 is counted in synchronization with the clock pulses for controlling the drive of the rotating mirror 18 described above. Counter 3 that performs the action
In the embodiment, both counters 32 and 34 are formed from preset counters.

In the present invention, since the object to be measured 10 has a poor end surface condition and light is refracted or scattered at the end surface, or the object to be measured 10 is made of a transparent material, the measurement light 100 is transmitted inside the object to be measured 10. Even when a large number of approximate detection signals are generated by the light detection section 26 through the light detection section 26, accurate measurement is possible by selecting these signals. During this process, the first detected light detection signal is used as the detection signal for one end face (starting end) of the object to be measured 10, and all subsequent detection signals, including pseudo signals, are latch-controlled and used to detect the last detected signal. The present invention is characterized in that the detected light detection signal is used as the correct detection signal for the other end face. That is, according to the present invention, the pair of counters 3 described above correspond to the correct detection signal and the pseudo detection signal, respectively.
2 and 34 are complementary to each other and are alternately counted, and the respective counted values are latched into correspondingly provided registers. As a result, only the clock pulses while the measurement light 100 passes through the object to be measured 10 are stored in one of the registers, and by adding the contents of both register signals, the desired signal can be obtained. Measured values are obtained.

In order to detect both ends of the scan area, in the present invention, at least a pair of scan start sensor 36 and scan completion sensor 38 are provided within the scan range of the parallel scan measurement light, and these sensors are made of photoelectric conversion elements. , when the parallel scanning measurement light 100 passes through both sensors 36 and 38, electrical signals are detected to define both ends of the desired scanning area.

In the embodiment, only one pair of both sensors 36 and 38 is provided, but by providing a plurality of pairs corresponding to desired segments, the scanning range of the parallel scanning measurement light 100 can be divided into a plurality of segmented scanning regions. It is also possible to divide the

In the present invention, the counters 32 and 34 can perform a desired measurement operation by counting the clock pulses supplied from the clock pulse generation circuit 22 during the detection period of both ends of the object to be measured 10. , the outer diameter of the object to be measured 10 such as a glass pipe can be accurately measured. However, as described above, when the surface of the object to be measured 10 is irregular or includes an opaque area, the light detection section 26 does not detect a detection signal when the measurement light scans not only both ends but also other parts. There is a problem that these false detection signals cannot be distinguished from the correct termination signal.
In the present invention, both the above-mentioned correct detection signal and pseudo detection signal are processed as correct detection signals for one day, that is, the counters 32 and 34 mutually perform their counting operations in response to these detection signals. By this, when one side is performing a counting action and a detection signal is received, the counting action is switched to the other one, and by repeating this, the measurement light 100 passes through the object to be measured 10. The clock pulses are counted by one of the counters during the period during which the measurement light 100 is thought to be passing through the object 10. When this count value is latched in the corresponding register, a judgment is made based on whether or not the measurement light 100 is passing through the object 10. . That is, either one of the counters 32 or 34 may perform a useless counting operation;
Depending on whether or not this is latched into the corresponding register, it is possible to select between a correct count signal and a useless count signal.

In normal cases, latching from the counter to the register takes the necessary circuit time, i.e., in high-precision measurement equipment such as the present invention, the clock pulse frequency reaches 50-100 MHz; It takes a certain amount of time to count up to the most significant bit in the counters 32 and 34, and for this reason, a non-negligible miscount occurs when performing a latch operation in a pair of correspondingly provided registers 40 and 42. may occur. Normally, this miscount occurs because the counters 32, 34 accept the next clock pulse while the registers 40, 42 correct the count values of the counters 32, 34 and latch them. The problem arises from the fact that the count values of the counters are updated sequentially, and therefore, with the configuration in which the registers 40 and 42 appropriately latch the contents of the counters 32 and 34 as described above, the count values cannot be read correctly.

Therefore, in the present invention, the counters 32 and 34 are used as counters 32 and 34 that count complementary to the above-mentioned counters, and while the detection signal from the photodetector 26 is being output, an inverting circuit, a flip-flop (hereinafter referred to as FF) is used in the embodiment. The counting function of each counter 32, 34 is switched in a complementary manner by an inverted signal from 44 (referred to as 1), and the count value of each counter 32, 34 is latched and outputted to registers 40, 42 at this inversion timing. This makes it possible to ensure a sufficient latch time since the latch time corresponds to the period during which the other counter is counting.

The counting action of the counters 32 and 34 is controlled by the output of the photodetector 26, and the
The detection signal from 0 is supplied to an edge pulse generator 48 via an amplifier 46, and the edge of the change in brightness of the light is detected by its differential action. The output of the edge pulse generator 48 is used to set the FF50, which is used to set the parallel scanning measurement beam 1.
It is set every time the starting end of the object to be measured 10 is detected for each scan of 00, and its output supplies a signal to AND gates 52 and 54 provided corresponding to each counter 32 and 34, respectively.

Moreover, FF50 is the scan completion sensor 38 mentioned above.
In the embodiment, the output of the sensor 38 is connected to the reset terminal of the FF 50 via a preamplifier 56 and a waveform shaping circuit 58.

The aforementioned inversion circuit 44 is controlled by both the output of the amplifier 46 and a signal obtained by slightly delaying the edge pulse of the edge pulse generator 48 in the delay circuit 56, and sends a complementary inversion signal to the AND gates 52, 54. supply to. Each and gate 5
2 and 54 are further supplied with clock pulses from the clock pulse generation circuit 22 mentioned above.
Further, each output is provided by the pair of counters 32 and 34 mentioned above.
From this, it can be seen that the pair of counters 32, 34 count clock pulses alternately and complementary to each other by the output of the inverting circuit 44.

Moreover, the inverted signal that is the output of the inverting circuit 44 is
Furthermore, it is also used as a latch signal for the registers 40 and 42 described above, and for this purpose, the output of the inverting circuit 44 is sent to each register 40 through a delay circuit 58, a falling edge pulse detector 60, and a falling edge pulse detector 62, respectively. , 42, and the count values of the corresponding counters 32, 34 are stored in the registers 40, 42 at this latch timing. Therefore,
This latching effect occurs only while the measuring light 100 is passing through the object 10 to be measured.
42 and after the measurement light 100 leaves the object to be measured 10, this problem will not occur, even if each counter 32, 34 performs a counting operation in vain. The registers 40 and 42 do not receive unnecessary count outputs.

In the illustrated embodiment, the measurement of the object to be measured 10 is performed by scanning the measurement light multiple times, and a programmable counter 64 is provided to count the number of scans. The output of the sensor 36 is supplied via a preamplifier 66 and a waveform shaping circuit 68, and the number of scans of the measurement light 100 is counted. Further, this scan start signal is simultaneously supplied to the load inputs of the counters 32 and 34, and at the start of each scan, the contents of the registers 40 and 42 are read into the corresponding counters 32 and 34, respectively.

Further, in the present invention, the clock pulse corresponding to the length of the object to be measured 10 is transmitted to the registers 40 and 42.
Since it is necessary to add these measured values after completing each optical scan, an adder 70 is provided for this purpose, and the contents of both registers 40 and 42 are added after each scan is completed. Ru.

The counters 32, 34 and registers 40, 4
A CPU 72 is provided to control other operations of the adder 70, and when the scanning of the measurement light 100 is completed for a predetermined number of scans set by the CPU 72, the CPU 72 takes in the contents of the adder 70,
Although not shown in detail, a well-known arithmetic circuit performs averaging calculations and other measurement calculations on the final latch value, and supplies the results to a display device. After this operation is completed, the clear pulse generator 74 outputs a clear signal to clear the contents of the counters 32 and 34.

The present embodiment has the above-mentioned configuration, and its operation will be explained in detail below with reference to the overall timing chart of FIG. 2.

As shown in FIG. 2, the object to be measured 10 itself has a transparent cylindrical shape made of glass or the like, but it is assumed that a foreign object 10a such as oil or dust is attached to a part of its surface. Therefore, while the measurement light 100 scans the object to be measured 10, it generates some pseudo detection signals from areas other than both end faces thereof.

The illustrated timing chart shows a state in the middle of multiple scans, and the start signal 300 of the scan start sensor 36 is detected by the counters 32 and 3.
4, the latch values of the corresponding registers 40 and 42, that is, the latch values accumulated up to the previous time, are supplied to the counters 32 and 34.
loaded. Further, this start signal 300 is counted by the programmable counter 64 as the number of scans.

When the measurement light 100 is scanned and reaches the starting end of the object to be measured 10, the output signal 200 of the amplifier 46 is changed due to the light shielding effect of the object to be measured 10 due to the detection signal from the photodetector 26. Then, the signal changes to the "H" level for detecting a dark signal, and is thereafter output as a photodetection signal containing some pseudo signals due to light blocking and light transmission by the object to be measured 10. The detection signal 200 in the embodiment includes correct detection signals corresponding to both ends of the object to be measured 10 and the above-mentioned foreign object 1.
It is shown as a pseudo signal 200a corresponding to 0a.

The detection signal 200 is generated by the edge pulse generator 48.
differentiated by . An edge pulse 202 is output every time there is a change in brightness, as is clear from the timing chart in FIG. The FF 50 is set by an initial rising edge pulse, that is, a pulse corresponding to the starting edge of the object to be measured 10, and a signal 204 is supplied to both AND gates 52 and 54, thereby creating a waiting state for each AND gate 52 and 54 to open.

The characteristic feature of the present invention is that the amplifier 4
The inverting circuit 44 is controlled to be inverted by the detection signal 200 which is the output of the counter 6 and the signal obtained by slightly delaying the edge pulse 202, and the complementary inverting signals 206a and 206b which are the outputs thereof are sent to each counter 32. , 34, and also controls the latch action of each register 40, 42.

As is clear from FIG. 2, when one of the complementary inverted signals 206a and 206b is at an H level, the other becomes an L level, thereby causing the counter 32, which receives signals from the AND gates 52,
When one side is counting clock pulses, the other side stops counting, thereby achieving complementary counting operations of counters 32 and 34.

However, such counters 32, 34
If only complementary counting is performed, one of the counters will continue counting even after the measurement light 100 passes the end of the object to be measured 10, making correct measurement impossible. In the invention, in order to avoid such a situation, the output of each counter 32, 34 is stored in the corresponding register 4.
The timing to latch to 0, 42 is extracted from the inverted signals 206a, 206b, and the counters 32, 34 are determined by the latch pulses 208a, 208b.
The measurement light 100 is characterized in that it sends the counted value to the registers 40 and 42 and discards it without any latching after the measurement light 100 passes the end end of the object to be measured 10.

Of course, in the present invention, since one of the counters performs the counting operation in a complementary manner, each of the above-mentioned latching operations is given sufficient time, so that even when the clock pulse is at a significantly high frequency, e.g. 50-100 MHz, The stable count value of the counter can be latched into a register.

Therefore, in FIG.
The counting pulses are shown as 210a and 210b, and these clock pulses are counted even after the measurement light 100 passes through the object to be measured 10, but the count value after passing through the object to be measured 10 is not stored in the registers 40, 210b. 42, the contents stored in the register indicate that the measurement light 100 is not latched to the object 10.
It is understood that only the clock pulse counts while passing through.

The scan completion sensor 38 described above immediately before the completion of each scan
The FF 50 is reset by the end signal 302 from the FF 50 and prepares for the next scan.

Then, upon completion of each scan, the measured values stored in the respective registers 40, 42 are added by an adder 70, and the complementary measured values are summed and
measurements are obtained.

When multiple scans are completed as described above,
The CPU 72 takes in the cumulative measurement value latched in the adder 70, performs averaging and other predetermined operations on it, and displays it as an accurate measurement value.

[Effects of the Invention] As explained above, according to the present invention, a pair of counters complementarily counts the clock pulses while the measurement light scans the object to be measured, and the counted contents are sequentially latched in the register. This method has the advantage of making error-free measurements possible.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing a preferred embodiment of the optical measuring device according to the present invention, and FIG. 2 is an overall timing chart for explaining the measurement operation in the embodiment of FIG. 1. 10...Object to be measured, 12...Light scanning unit, 22...
...clock pulse generation circuit, 26...photodetection section,
32, 34... Counter, 36... Scanning start sensor, 38... Scanning completion sensor, 40, 42... Register, 44... Switching circuit, 100... Parallel scanning measurement light, 200... Detection signal, 206a, 206
b...Clock pulse, 208a, 208b...
Latch pulse.

Claims (1)

[Scope of Claims] 1. A light scanning section that irradiates parallel scanning measurement light onto the object to be measured, and a light detection section that detects changes in brightness of the measurement light that has passed through the object to be measured and outputs a light detection signal. ,
An optical measuring device that includes a counter that counts predetermined clock pulses during an optical scanning period and determines the length of an object to be measured based on the counter count value while the parallel scanning measurement light passes through the object. an inverting circuit that outputs inverted signals respectively based on the starting edge and ending edge detection signals and pseudo detection signals detected while the object to be measured passes from the starting edge to the ending edge; A pair of counters for counting, a pair of registers for latching the contents of each counter at each reversal timing while the measurement light passes through both ends of the object to be measured, and a pair of registers for adding the contents of each register each time the measurement light finishes scanning. The clock pulse is counted alternately by one of the counters according to the correct detection signal and the pseudo detection signal, and the length of the object to be measured is measured by adding the two. Optical measuring device. 2. An optical measuring device according to claim 1, wherein the parallel scanning of the measurement light is repeated a plurality of times, and the average value is output after a predetermined number of scans are completed.