JPH048325Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

The present invention relates to an optical dimension measuring device, and in particular,
A light emitting means suitable for use in a high-speed scanning laser length measuring machine that measures the dimensions of a workpiece using a barely visible or invisible laser beam, and a light beam generated by the light emitting means that is parallel to each other. It is equipped with a parallel scanning beam generating means for converting into a scanning beam, and a light receiving means for detecting the brightness and darkness of the scanning beam that has passed through the object to be measured. The present invention relates to an improvement of an optical dimension measuring device for measuring the dimensions of an object to be measured.

[Conventional technology]

Conventionally, a light beam generated by a light emitting means is converted into a rotating scanning beam using a rotating mirror, etc.
The rotating scanning beam is collimated by a collimator lens.
The beam is converted into a parallel scanning beam that passes between the collimator lens and the condensing lens, an object to be measured is placed between the collimator lens and the condensing lens, and a light receiving means detects the brightness of the scanning beam that has passed through the object. A high-speed scanning laser length measuring machine is known that measures the dimensions of an object to be measured based on the length of a dark or bright area that is generated when a parallel scanning beam is interrupted by the object. For example, as shown in FIG. 6, a laser beam 12 is oscillated from a laser light source 10 toward a fixed mirror 14, and the laser beam 12 reflected by the fixed mirror 14 is transmitted to, for example, a polygonal rotating mirror 16. The rotating scanning beam 17 is converted into a parallel scanning beam 20 by the collimator lens 18, and the object to be measured placed between the collimator lens 18 and the condensing lens 22 is The object 24 is scanned at high speed, and the dimension of the object 24 in the scanning direction is measured from the length of time of a dark or bright area generated by the object 24. That is, the brightness and darkness of the parallel scanning beam 20 is detected as a change in the output voltage of the light receiving element 26 located at the focal position of the condensing lens 22, and the signal from the light receiving element 26 is input to the preamplifier 28, where it is After being amplified, it is sent to the segment selection circuit 30. This segment selection circuit 30
In order to select a specific dark area or bright area (hereinafter referred to as a measurement segment) to be measured from among all the dark areas or bright areas generated when the parallel scanning beam 20 is interrupted, the output of the light receiving element 26 is A voltage V for opening the gate circuit 32 is generated and output to the gate circuit 32 only during the time t during which the measurement segment of the object to be measured 24 is being scanned. Since the clock pulse CP is inputted to this gate circuit 32 from the clock pulse oscillator 34, the gate circuit 32 outputs the clock pulse P corresponding to the time t corresponding to the scanning direction dimension of the measurement segment of the object 24 to the counting circuit 32. Enter. The counting circuit 36 counts the clock pulses P and outputs a counting signal to the digital display 38.
The digital display 38 will digitally display the dimension of the measurement segment of the object 24 in the scanning direction. On the other hand, the rotating mirror 16 is synchronized with the clock pulse CP output from the clock pulse oscillator 34 by a frequency dividing circuit 40 that divides the output from the clock pulse oscillator 34 and a synchronous motor 44 which is synchronously driven by the output of the power amplifier 42. and rotated to maintain measurement accuracy. Such high-speed scanning laser length measuring machines are becoming widely used because they can measure the length, thickness, etc. of moving objects or high-temperature objects with high precision in a non-contact manner.
In addition, as the application expands to hand-held and in-process measurement, further miniaturization is desired, and the laser light source 1
0 as a semiconductor laser is being proposed.

[Problem that the invention attempts to solve]

However, a laser diode LD used in a semiconductor laser light source has a light output-current characteristic as shown in FIG. 7, for example, and the characteristic varies greatly depending on the operating temperature and the like. Therefore, as shown in Fig. 8, an automatic output control circuit (hereinafter referred to as APC) is generally used that incorporates a photodiode PD for monitoring and controls the output of the laser diode LD while feeding back the output of the photodiode PD. (referred to as a circuit),
Generally, the amount of light emitted is maintained by the laser light source itself. By using this APC circuit, even if the temperature changes during measurement, for example, a constant light output can always be obtained and the amount of light emission will not fluctuate. However, because of this, and because the laser beam is invisible to the naked eye, in the past, even if the operating environment temperature was too high and a large current was flowing through the laser diode LD, the measurer did not take any measures to improve the situation. The laser diode LD may be overloaded by the large current and its lifespan may be shortened. In addition, even if the lifetime of the laser beam reaches the end of the measurement and the amount of light emitted decreases drastically or disappears and the laser beam ceases to emit light, the operator will not notice this because the laser beam cannot be seen with the naked eye, and as a result, the measurement will become invalid. This has had problems such as aging and product defects. Furthermore, conventionally, in order to prevent an unexpected accident such as a measurement person looking directly into the scanning beam, it has been necessary to provide a mechanical shutter with many restrictions in terms of placement.

[Purpose of invention]

The present invention has been developed to solve the above-mentioned conventional problems, and prevents erroneous measurements due to scanning abnormalities caused by abnormal operation of the laser beam generating semiconductor element or uneven rotation of the rotating mirror, etc., thereby ensuring reliable measurement. Another object of the present invention is to provide an optical dimension measuring device that can protect a measurer without using a mechanical shutter.

[Means to solve the problem]

The present invention includes a light emitting means, a parallel scanning beam generating means for converting the light beam generated by the light emitting means into a parallel scanning beam, and a light receiving means for detecting the brightness of the scanning beam that has passed through the object to be measured. In an optical dimension measuring device that measures the dimensions of an object to be measured based on the length of a dark or bright area generated when a parallel scanning beam is interrupted by the object, the light emitting means is configured with a laser light generating semiconductor element. At the same time, voltage detection means for detecting the actual load of the semiconductor element, comparison means for comparing the output voltage of the voltage detection means with a variable reference voltage, and generating the laser beam based on the output of the comparison means. a display means for displaying information regarding abnormal operation of the semiconductor element; at least one set of light receiving elements arranged apart in the scanning direction within the scanning area of the light beam; and a display means for displaying information regarding abnormal operation of the semiconductor element; The above object is achieved by providing a scanning abnormality detection means for detecting an abnormality, and a power cutoff means for cutting off the power to the light emitting means based on the outputs of the scanning abnormality detection means and the comparison means.

[Effect]

In the present invention, in the optical dimension measuring apparatus as described above, the light emitting means is constituted by a laser beam generating semiconductor element, and a voltage detecting means for detecting the actual load of the semiconductor element, and a voltage detecting means for detecting the actual load of the semiconductor element are provided. a comparison means for comparing the output voltage with a variable reference voltage; a display means for displaying information regarding abnormal operation of the laser beam generating semiconductor element based on the output of the comparison means; at least one set of light receiving elements arranged separately from each other, a scanning abnormality detection means for detecting a scanning abnormality from an output interval of the light receiving elements, and a scanning abnormality detection means based on the outputs of the scanning abnormality detection means and the comparison means. A power cutoff means for cutting off the power to the light emitting means is provided. Therefore, it is possible to prevent erroneous measurements due to scanning abnormalities caused by abnormal operation of the laser beam generating semiconductor element or uneven rotation of the rotating mirror, thereby ensuring reliable operation, and without using a mechanical shutter.
The measurer can be protected.

【Example】

Embodiments of the present invention will be described in detail below with reference to the drawings. As shown in FIG. 1, this embodiment includes a laser light source 10, a fixed mirror 14, a rotating mirror 16, a collimator lens 18, a condensing lens 22, a light receiving element 26, a preamplifier 28, and a segment selection circuit similar to the conventional example. 30, gate circuit 32, clock pulse oscillator 34, counting circuit 36, digital display 3
8. An optical dimension measuring device equipped with a frequency dividing circuit 40, a power amplifier 42, and a synchronous motor 44,
The laser light source 10 is configured using a semiconductor laser emitter 50 including a laser diode LD and a photodiode PD, and a resistor 52 for detecting the actual load (current) of the laser diode LD as a voltage; a comparator 56 for comparing the output voltage Va of the laser diode with a reference voltage Vref adjusted by a variable resistor 54, and a light emitting diode 58 for displaying information regarding the operating state of the laser diode LD based on the output of the comparator 56. A laser diode abnormality detection circuit 51 including the laser diode abnormality detection circuit 51 is further provided. In addition to the semiconductor laser emitter 50 and the resistor 52, the laser light source 10 includes a power supply circuit 60,
A slow start circuit 62 and an APC circuit 64 are included to slowly start up the power supply to prevent surges. The slow start circuit 62 is configured as shown in FIG. 2, for example. The APC circuit 64 is configured as shown in FIG. 3, for example, and controls the output transistor 64A so that the amount of light emitted from the laser diode LD detected by the photodiode PD is constant. The laser diode abnormality detection circuit 51 is configured as shown in FIG. reference value (potential difference between TP1 and TP3 Vref
For example, the light emitting diode 58 is turned on when the current reaches 1.5 times the initial value, which is generally considered to be the lifespan of an LD. The output of the laser diode abnormality detection circuit 51 is input not only to the light emitting diode 58 but also to other means, such as an input port 66 of the computer of the optical dimension measuring device. Thereby, the computer can monitor the output of the laser diode abnormality detection circuit 51 at power-on or at all times, and if an abnormality occurs, it can display it as an error message on the display section of the dimension measuring device. Also, a buzzer can be used instead of the light emitting diode 58. Therefore, with these displays, a person measuring the laser diode LD can easily know about abnormal operation, and can, for example, improve the usage environment and extend the life of the laser diode LD. Furthermore, it is possible to indicate the deterioration (time for replacement) of the laser diode LD. Furthermore, it is also possible to cut off the current of the laser diode LD. Rotating scanning beam 17 by the rotating mirror 16
At the upper and lower limits of the scanning range, light receiving elements 70 and 72 are provided for managing the passing time of the scanning range. The outputs of these light receiving elements 70 and 72 are input to a scanning abnormality detection circuit 74.
If the scanning time measured in step 4 is outside the setting range,
When it is determined that rotational unevenness (scanning disturbance) of the rotating mirror 16, which is a typical error factor, has occurred,
The power supply circuit 60 of the laser light source 10 is cut off. This makes it possible to prevent unforeseen accidents such as a measurement person looking directly into the scanning beam without using a conventional mechanical shutter that has many restrictions in terms of arrangement. Note that the arrangement positions of the light receiving elements 70 and 72 are as follows.
It may also be within the scanning range of the parallel scanning beam 20, as indicated by the broken line in the figure. Abnormality detection and countermeasures in the scanning abnormality detection circuit 74 are executed according to the flowchart shown in FIG. That is, first, in step 110, it is confirmed that the power supply circuit 60 of the laser diode LD is on. Next, the process proceeds to step 112, where an abnormality detection counter for detecting an abnormality in the scanning time is set. Next, the process proceeds to step 114, where the output of the input side light receiving element 70 is detected. Then step 1
16, the output of the output light receiving element 72 is detected. Steps 112-116 are repeated at approximately 3 millisecond intervals. The process then proceeds to step 118, where it is determined whether an abnormality in scanning time has been detected. If the determination result is negative and it is determined that normal scanning is being performed, the process proceeds to step 120, cancels the error message, and proceeds to normal processing. On the other hand, if the determination result in step 118 is positive and it is determined that the scanning time is not constant and the scanning is abnormal, the process proceeds to step 122 and the power supply circuit 60 is turned off. Then step 1
Proceed to step 24 to display an error message. The process then proceeds to step 126, where the standby state is maintained for about 1 second. Next, the process proceeds to step 128, where the power supply circuit 60 is turned on. Next, the process advances to step 130, and after a standby state of about 1 second, the process returns to step 112 described above. The reason why the standby state is set for about 1 second is that the power supply for the laser diode LD includes the slow start circuit 62 as a surge countermeasure. The foregoing steps 122-130 take approximately 2 seconds, so if an abnormality occurs, the on/off cycle of the laser diode LD will be approximately 2 seconds. At this time, the light output is about 0.5 seconds. In this embodiment, since the operating information detected by the laser diode abnormality detection circuit 51 indicates that the life of the laser diode LD has come to an end, that is, it is time to replace the semiconductor laser emitter 50, the semiconductor element It is possible to accurately judge when to replace the Note that the operating information to be detected by the laser diode abnormality detection circuit 51 is not limited to this, and by changing the reference voltage Vref using the variable resistor 54, for example, the reference voltage Vref can be set to a low value, and the lifespan can be adjusted. It is also possible to receive a warning requesting improvement of the operating temperature environment before this occurs. In this case, in this embodiment, since the reference voltage Vref can be changed by the variable resistor 54,
Any driving information can be easily obtained. Further, in this embodiment, a scanning abnormality detection circuit 74 is provided in addition to the laser diode abnormality detection circuit 51, and when a scanning abnormality is detected by the scanning abnormality detection circuit 74, the power supply circuit 60 is cut off. Therefore, the operator can be protected without using a mechanical shutter.

【Effect of the invention】

As explained above, according to the present invention, it is possible to prevent erroneous measurements due to scanning abnormalities caused by abnormal operation of the semiconductor laser emitter or uneven rotation of the rotating mirror, to ensure reliable measurement, and to use a mechanical shutter. This has the excellent effect of protecting the person performing the measurement without any trouble.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of an optical dimension measuring device according to the present invention, and FIG. 2 is a circuit diagram showing the configuration of a slow start circuit used in the embodiment. Figure 3 is the same
FIG. 4 is a circuit diagram showing the configuration of the APC circuit, FIG. 4 is a circuit diagram showing the configuration of the laser diode abnormality detection circuit, FIG. 5 is a flowchart showing the procedure for abnormality detection and countermeasures for the scanning abnormality detection circuit, The figure is a block diagram showing the configuration of an example of a conventional optical dimension measuring device, Figure 7 is a diagram showing an example of the relationship between the optical output and current of a laser diode, and Figure 8 is a diagram showing the internal circuit. FIG. 10... Laser light source, 16... Rotating mirror, 1
7... Rotating scanning beam, 18... Collimator lens, 20... Parallel scanning light beam, 24... Measured object, 26, 70, 72... Light receiving element, LD...
Laser diode, 50... Semiconductor laser emitter, 51... Laser diode abnormality detection circuit, 5
2... Resistor, 54... Variable resistor, Vref... Reference voltage, 56... Comparator, 58... Light emitting diode, 60... Power supply circuit, 64... Automatic output control (APC) circuit, 74... Scanning Abnormality detection circuit.

Claims (1)

[Claims for Utility Model Registration] A light emitting means, a parallel scanning beam generating means for converting the light beam generated by the light emitting means into a parallel scanning beam, and a light receiving means for detecting the brightness of the scanning beam that has passed through the object to be measured. In an optical dimension measuring device that measures the dimensions of an object to be measured from the length of a dark or bright area generated when the parallel scanning beam is blocked by the object, the light emitting means being a laser beam generator. a voltage detection means for detecting the actual load of the semiconductor element; a comparison means for comparing the output voltage of the voltage detection means with a variable reference voltage; and a voltage detection means for comparing the output voltage of the voltage detection means with a variable reference voltage; a display means for displaying information regarding abnormal operation of the laser beam generating semiconductor element; at least one set of light receiving elements disposed apart from each other in the scanning direction within the scanning area of the light beam; and an output of the light receiving element. An optical system comprising: a scanning abnormality detection means for detecting a scanning abnormality from an interval; and a power cutoff means for cutting off power to the light emitting means based on the outputs of the scanning abnormality detection means and the comparison means. Type dimension measuring device.