JPH0716963Y2 - Optical scanning measuring device - Google Patents

Description

[Detailed description of the device] [Industrial applications]

The present invention relates to an optical scanning type measuring apparatus, and more particularly, to an optical scanning type measuring apparatus suitable for use in measuring a transparent body, which measures a dimension or the like of an object to be measured using a laser beam. It is about improvement.

[Prior art]

Conventionally, a rotating or oscillating scanning beam (laser beam) is converted by a collimator lens into a parallel scanning beam that passes between the collimator lens and the condenser lens, and the above-mentioned object is placed between the collimator lens and the condenser lens. There has been an optical scanning type measuring device that measures the dimension of a measurement target in the scanning direction from the length of time of a dark portion or a bright portion that is generated by blocking a part of a parallel scanning portion. When measuring a transparent body using such an optical scanning type measuring apparatus, the intensity of the parallel scanning beam 20 passing through the transparent body 22 becomes indefinite as shown in FIG. 4, and as shown in FIG. Since an edge also occurs inside the transparent body 22, the outer diameter of the transparent body 22 cannot be obtained by simply counting the time of each edge and, for example, the reset signal which is a reference signal. Therefore, as shown in FIG. 6, a shift register 56A whose output is shifted each time a composite edge signal of a rising edge and a falling edge is input, and a first output A of the shift register 56A, that is, a first scanning signal The counting of the clock is started by the rising edge of the rising edge of and the counting is stopped by the rising of the reset signal, so that the time from the first rising edge to the reset signal CNT1 (fifth
The first counter 58A for counting (see the figure) and the second output B of the shift register 56A, that is, the counting of the clock is started by the rising edge of the first falling edge of the scanning signal, and is counted by the rising edge of the reset signal. Stop the second counter 58B that counts the time CNT2 (see FIG. 5) from the first falling edge to the reset signal, and the next output C of the shift register 56A causes the clock to count. The time from the last rising edge to the reset signal starts by being cleared to 0 each time the rising edge of the scanning signal is detected.
It was equipped with a third counter 58C for counting CNT3 (see FIG. 5). That is, according to the circuit of FIG. 6, as shown in FIG.
Since the time CNT3 of the last rising edge can be counted by the third counter 58C, the outer diameter of the transparent body 22 is, for example, the count value CNT2 of the second counter 58B as shown in FIG.
And the difference between the count value CNT3 of the third counter 58C (CNT2-CNT3).

[Issues to be achieved by the device]

However, conventionally, the first and second counters 58A, 5
8B starts counting with rising edge or falling edge, while the third counter 58C
First, as shown in FIG. 7, first, the count value is cleared to 0 by a clear pulse obtained by the rising edge of the scanning signal,
Counting is started only after the clear pulse disappears. Therefore, the operation of the third counter 58C is stopped for the time corresponding to the width of the clear pulse, and the counting start is delayed,
There is a problem that the time of the rising edge of the last rising edge cannot be accurately measured. In particular, when the clock of the counter is increased to the upper limit of the used element in order to increase the resolution or shorten the measurement time, the width of the clear pulse becomes close to the width of the clock pulse. In addition, due to the delay of the gate circuit and the like, there is a problem in that the count value is reduced by 1 to 2 clocks per scan in total, and the size of the transparent body 22 is increased accordingly.
For example, in the case of an optical scanning measuring device having a measuring unit with a basic resolution of 0.8 μm and a display unit of 0.1 μm, for example, the accuracy is improved by averaging the count values, and the physically determined resolution is 0.1 μm. 0.8-1.6 in the data obtained
A measurement error of μm is included. The present invention has been made to solve the above-mentioned conventional problems, and it is possible to eliminate an error when measuring a transparent body, and there is no need to change the measuring method or the calibration method between the transparent body and the opaque body. An object is to provide a measuring device.

[Means for achieving the object]

The present invention is directed to a collimator lens that uses a rotating or oscillating scanning beam as a parallel scanning beam, a light receiving element for measurement that detects the brightness of the parallel scanning beam that has passed through a measurement target, and a waveform shaping of the light receiving element output to obtain an edge. An edge detection circuit for detecting a change in the scanning direction of the measurement target by detecting switching to a dark part or a bright part caused by a part of the parallel scanning beam being blocked by the measurement target. In the optical scanning measuring device, every time the rising edge of the received light signal is detected, or the flip-flop whose output is inverted every time the rising edge is detected, and when the output of the flip-flop is at one level, counting is performed, The counter value is cleared when it reaches the other level, and counting is performed when the inverted output of the flip-flop is at one level. , A pair of counters which consist of the other counter whose count value is cleared when the level of the other counter is reached, and when the count value of one counter is counting, the count value of the other counter is cleared The above object is achieved by determining the time of the last rising edge or the last falling edge of the received light signal by using the count values of the pair of counters. Also, the time of the last rising edge or the last falling edge is obtained from the sum of the count values of the pair of counters.

[Action and effect]

In the present invention, the counter for counting the last rising time of the scanning signal is not cleared to 0 by the clear pulse at each rising edge as in the conventional case, but is detected every time the rising edge of the light receiving signal is detected or the rising edge is detected. A flip-flop whose output is inverted each time a falling edge is detected is provided, counting is performed when the output of the flip-flop is at one level, and the count value is cleared when the output reaches the other level, and , The other counter which counts when the inverted output of the flip-flop is at one level and which clears the count value when it reaches the other level, and when one counter is counting,
Counting is performed by a pair of counters in which the count value of the other counter is cleared.
Therefore, both of the pair of counters start counting at the rising edge or the falling edge of the light receiving signal like the other counters, and therefore, even when measuring the transparent body,
The timing at which the counters start counting is
The rising edge of the scanning signal is standardized. Therefore, the measurement error of the clear pulse which is higher than the physically determined resolution, which is present when the transparent body is measured, can be eliminated, and the transparent body can be measured with the same high precision as the opaque body.
Further, it is not necessary to separate the measuring method and the calibrating method for the transparent body and the opaque body, and the reference body for calibration, which has been conventionally provided for the transparent body and the calibration body for the opaque body, can be shared, so that the cost can be reduced. . Since either one of the count values of the pair of counters is always cleared to 0, the time of the last rising edge or the last falling edge is obtained from the sum of the count values of the pair of counters. In such a case, the configuration is particularly simple.

【Example】

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. As shown in FIG. 2, the measuring unit of the present embodiment uses a laser light source 10
A polygon mirror 14 for converting the laser beam 12 generated by the laser light source 10 into a rotary scanning beam 16; a collimator lens (fθ lens) 18 for converting the rotary scanning beam 16 into a parallel scanning beam 20; A condenser lens 24 for condensing the parallel scanning beam 20 that has passed through the measurement object 22,
It is mainly composed of a light receiving element 26 for measurement for detecting the light and darkness of the light condensed by the condensing lens 24, and an amplifier 48 for amplifying the output of the light receiving element 26. In the figure, 28 is a mirror that is arranged as necessary for applying the laser beam 12 emitted from the laser light source 10 to the reflecting surface of the polygon mirror 14, and 30 is a motor for rotating the polygon mirror 14, Reference numeral 32 denotes a reset light receiving element which is arranged outside the effective scanning range of the rotary scanning beam 16 or the parallel scanning beam 20 and detects the start or end of one scanning. In addition, the display unit of this embodiment has a central processing unit (CPU) 40 for performing various arithmetic processings, as also shown in detail in FIG.
And a keyboard and display circuit 42 for giving necessary instructions to the CPU 40 or displaying the calculation result by the CPU 40, etc.
I / O device 44, read-only memory (ROM),
A storage device 46 such as a random access memory (RAM), an edge detection circuit 50 for performing waveform detection on the output of the amplifier 48 to perform edge detection, and an edge of the output of the reset photodetector 32 to detect a reset signal. Reset circuit 52 for
A gate circuit according to the present invention for passing a clock 54 for generating a clock signal and a clock signal for a predetermined edge detected by the edge detection circuit 50 and a reset signal.
56, a counter 58 according to the present invention for counting the clock signals passing through the gate circuit 56, and detecting the length of time between predetermined edges and the reset signal,
It is mainly composed of a motor synchronization signal generator 60 which generates a synchronization signal for driving the motor 30 in synchronization with the clock signal of 54 output. In the figure, 62 is a motor drive circuit for driving the motor 30 according to the output of the motor synchronization signal generator 60,
Reference numeral 64 denotes the laser light source 10 in accordance with the output of the reset light receiving element 32 after waveform shaping inputted from the reset circuit 52.
This is a laser output adjustment circuit that automatically adjusts the output of the laser beam 12 generated from the device so as to be constant. As shown in detail in FIG. 1, the gate circuit 56 and the counter 58 shift their outputs each time a composite edge signal is input from the edge detection circuit 50, and the output is shifted by the reset signal input from the reset circuit 52. A shift register 56A to be reset, and a flip-flop 56B whose output is inverted each time a rising edge of a light receiving signal is detected, for example.
According to the first output A of the shift register 56A, a first counter 58 for counting the time CNT1 from the rising of the first rising edge of the scanning signal to the rising of the reset signal.
A, a second counter 58B for counting the time CNT2 from the falling edge of the first falling edge of the scanning signal to the rising edge of the reset signal in accordance with the second output B of the shift register 56A, and the flip-flop 56B. When the output Q of the counter is at the H level, the counter value is cleared when the output Q is at the L level and the counter 58P and the inverted output of the flip-flop are at the H level. The counter 58Q consists of the other counter 58Q whose count value is cleared when it becomes, and when one counter is counting, the pair of counters 58P and 58Q are arranged so that the count value of the other counter is cleared. And are provided. The operation of the embodiment will be described below with reference to FIG. The first counter 58A and the second counter 58B respectively count the time CNT1 from the first rise of the scan signal to the reset signal and the time CNT2 from the first fall of the scan signal to the reset signal as in the conventional case. There is. On the other hand, the counters 58P and 58Q alternately count according to the state of Q of the flip-flop 56B. That is, in the counter 58P, the output Q of the flip-flop 56B is H level.
Counting is performed when the level is set, and the count value is cleared to 0 when the level is set. The counter 58Q counts when the inverted output of the flip-flop 56B is at H level, and clears the count value to 0 when it is at L level. Therefore, the counters 58P and 58Q do not count at the same time. These counters 58P, 58Q
In addition to the output Q of the flip-flop 56B, the output B of the shift register 56A is also input to, and its AND processing causes the rising edge of the scanning signal to rise similarly to the first counter 58A and the second counter 58B. The correct data is obtained from counting. When reading the value CNT3 counted by the counter 58P or 58Q, the counter 58P may be read depending on the state of the measuring object.
It is uncertain whether data exists in P or 58Q. Therefore, either the output Q of the flip-flop 56B or the state of is determined and the count value of the corresponding one counter is read out, or the count value of the other counter is always 0.
The count values of the counters 58P and 58Q may be added. In this case, the configuration is simple. Generally, the optical scanning type measuring device has a function of simultaneously measuring a plurality of measurement objects, and has the number of counters (the number of measurement objects × 2 + 1). Therefore, in the case of such an optical scanning type measuring device, it suffices to change the usage of the counter, and the measurement error can be eliminated by adding one flip-flop. Further, in the present embodiment, the output B of the shift register 56A is input to the pair of counters 58P and 58Q so that the counting of the counters 58P and 58Q is not started until the second counter 58B starts to operate. Therefore, power consumption is saved. Although the present invention is applied to the one in which the rotary scanning beam 16 is generated by using the polygon mirror 14 in the above embodiment, the application target of the present invention is not limited to this, and for example, a tuning fork is used. Obviously, the same applies to those producing an oscillating scanning beam.

[Brief description of drawings]

FIG. 1 is a block diagram showing essential parts of a gate circuit and a counter used in an embodiment of an optical scanning type measuring apparatus according to the present invention, and FIG. 2 shows an overall configuration of the embodiment. FIG. 3 is an optical path diagram including a partial block diagram, FIG. 3 is a diagram showing signal waveforms of respective parts of the above-mentioned embodiment, and FIG. 4 is a situation in which a transparent body is being measured in an optical scanning type measuring device and a situation at that time. FIG. 5 is a diagram showing an example of a scanning waveform, FIG. 5 is a diagram for explaining the measuring principle of a transparent body in an optical scanning type measuring apparatus, and FIG. 6 is a conventional gate used for transparent body measurement. FIG. 7 is a block diagram showing an example of the configuration of a circuit and a counter, and FIG. 7 is a diagram showing an example of signal waveforms at various parts of the conventional example shown in FIG. 10 ... Laser light source, 12 ... Laser beam, 14 ... Polygon mirror, 16 ... Rotating scanning beam, 18 ... Collimator lens, 20 ... Parallel scanning beam, 22 ... Transparent object (measurement object), 26 , 32 …… light receiving element, 50 …… edge detection circuit, 52
...... Reset circuit, 56 …… Gate circuit, 56A …… Shift register, 56B …… Flip-flop (FF), 58, 58A,
58B, 58P, 58Q ... Counter.

Claims (2)

[Scope of utility model registration request] 1. A collimator lens that uses a rotating or oscillating scanning beam as a parallel scanning beam, a light receiving element for measurement that detects the brightness of the parallel scanning beam that has passed through a measurement target, and the output of the light receiving element is waveform-shaped. An edge detection circuit for detecting an edge is provided, and a switching to a dark part or a bright part caused by a part of the parallel scanning beam being blocked by the measurement object is detected, and the dimension in the scanning direction of the measurement object is obtained. In the optical scanning measuring device described above, a flip-flop whose output is inverted each time the rising edge of the received light signal is detected or each falling edge is detected, and when the output of the flip-flop is at one level, counting is performed. One counter that clears the count value when it reaches the other level and counts when the inverted output of the flip-flop is at one level The counter consists of the other counter that clears the count value when it goes to the other level. When one counter is counting, the counter value of the other counter is cleared. An optical scanning type measuring apparatus comprising: a counter, and the time of the last rising edge or the last falling edge of the received light signal is obtained from the count values of the pair of counters. 2. The optical scanning measuring device according to claim 1, wherein the time of the last rising edge or the last falling edge is obtained from the sum of the count values of the pair of counters.