JPH0528983U - Laser range finder - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain a laser distance measuring device that reduces a quantization error caused by a start signal and a stop signal of the laser distance measuring device not being synchronized with a clock signal. [Structure] A laser beam 2 emitted from a laser oscillator 1 irradiates a target 4. The reflected light 5 from the target is received and then amplified and becomes a reception signal 9, and becomes a stop signal 11 by the comparator 10. The stop signal 11 is input to both the counter 14 and the integrator 17. Integrator 17
The integrated signal of starts to rise from when the stop signal 11 is generated and is sampled and held by the next clock signal when the stop signal 11 is generated.
The / D converter 21 produces a stop signal strength 22 of a digital value, which is input to the calculation unit 23. The calculation unit 23 corrects the count value 15 of the counter using the function of the stop signal strength 22 and the time-voltage of the integrator to reduce the quantization error of the distance measurement value that has occurred in the conventional device. You can

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 This invention relates to an improvement of a laser distance measuring device.

[0002]

[Prior Art]

 FIG. 2 is a diagram showing an example of the configuration of a conventional laser distance measuring apparatus. 1 is a laser oscillator, 2 is a laser beam, 3 is a start signal, 4 is a target, 5 is reflected light from the target, and 6 is a light receiving element. , 7 is an electric signal, 8 is an amplifier, 9 is a received signal, 10 is a comparator, 11 is a stop signal, 12 is a reference time generator, 13 is a clock signal, 14 is a counter, 15 is a count value, and 16 Is an arithmetic unit.

Next, the operation will be described. The laser oscillator 1 emits a laser beam 2 and simultaneously generates a start signal 3. The laser light 2 propagates in space and irradiates the target 4. The reflected light 5 from the target propagates again in space and enters the light receiving element 6. The light receiving element 6 photoelectrically converts this light and outputs an electric signal 7. The electric signal 7 is amplified by the amplifier 8 and becomes the received signal 9. When the intensity of the received signal exceeds the threshold value of the comparator 10, the stop signal 11 is generated. The counter 14 counts the clock signal 13 of the reference time generator 12 during the time from the generation of the start signal 3 to the generation of the stop signal 11. The count value 15 is proportional to the time difference between the start signal and the stop signal. That is, it is proportional to the distance to the target. Based on this principle, the calculation unit 16 can calculate based on the count value 15 to calculate the distance to the target.

[0004]

[Problems to be solved by the device]

 The conventional device is configured as described above.Because the start signal and stop signal are not synchronized with the clock signal of the reference time generation unit, the time when the start signal and stop signal are generated is used as the reference time generation. A quantization error of ± 1 count occurred when the data was taken into the arithmetic unit at the timing of the clock signal of the unit. In order to reduce this quantization error, the frequency of the clock signal of the reference time generator is set as high as possible. For example, if a high speed CM OS logic IC is used as a digital element, the upper limit of the clock frequency that can be counted is about The frequency is 60 MHz, and the quantization error corresponds to 2.5 [m]. When an ECL type IC that can count up to a higher clock frequency is used for the above digital elements in order to reduce the quantization error, the power consumption is significantly increased, the power supply with negative polarity is increased, and However, there are problems that it is difficult to commercialize the product because of the increase in cost and the increase in size associated with it.

The present invention has been made in order to solve the above problems, and reduces a quantization error that occurs because the start signal and the stop signal are not synchronized with the clock signal of the reference time generation unit. The purpose is to obtain a device that can

[0006]

[Means for Solving the Problems]

 The laser range finder according to the present invention integrates the start signal, the stop signal, or both signals, and corrects the result of distance calculation according to the intensity of the integrated signal.

[0007]

[Action]

 Since the laser range finder in this invention corrects the result of distance calculation by the intensity of the start signal or the stop signal or the integrated signal of both, the start signal and the stop signal and the clock signal of the reference time generating section are synchronized. It is possible to reduce the quantization error caused by the lack of

[0008]

【Example】

 Example 1. An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 17 is an integrator, 18 is an integrated signal, 19 is a sample and hold device, 20 is a hold voltage, 21 is an A / D converter, 22 is a stop signal strength, and 23 is an arithmetic unit, which is from 1 to 15 Is the same as the conventional device described above.

Next, the operation will be described. In this example, reduction of the stop signal quantization error is described in order to avoid complication. To reduce the quantization error of the start signal, the exact same configuration may be applied to the start signal system. Now, until the laser light 2 is generated and the target 4 is irradiated, the reflected light 5 is incident on the light receiving element 6, and the electric signal 7 is amplified by the amplifier 8 to generate the stop signal 11, the above-mentioned conventional method is used. It is exactly the same as the device. The stop signal 11 is input to both the counter 14 and the integrator 17. The signals of the respective parts in this state are shown in FIG. The start signal 3 is described in synchronization with the clock signal 13 as described above, and the case where the quantization error does not occur is shown. Here, since the stop signal 11 is generated at a timing independent of the clock signal 13 as shown in FIG. 3, a quantization error of one clock is generated in the conventional device, but according to the present invention, the stop signal is generated. By integrating 11 with the integrator 17, an integrated signal 18 proportional to time is obtained as shown in FIG. Here, if the sample and hold device 19 is operated at the timing when the counter 14 stops counting, the hold voltage 20 becomes the value of "V" in FIG. The hold voltage 20 becomes a stop signal strength 22 of a digital value in the A / D converter 21 and is input to the calculation unit 23. Since the slope of the integrated signal 18 shown in FIG. 3 which is proportional to time is predetermined by the integrator 17, the arithmetic unit 23 calculates the distance based on the count value 15 of the counter to obtain the stop signal strength 22. It is possible to reduce the quantization error by using the correction.

In the above embodiment, the integrated value of the stop signal is sampled and held by the timing when the counter stops counting, but it may be performed at another timing. Further, in this example, the sample hold is performed once at the timing when the counting stops, but the accuracy may be further improved by performing the sample hold twice or more at the appropriate timing thereafter. Furthermore, the integrator may of course be one in which the integral value with respect to time is not directly proportional as long as the relation between the integral value with respect to time is clear in advance. Also, in this example, the method of counting the reference clock signal input between the start signal and the stop signal by the counter was explained, but for example, the timing of the start pulse and the timing of the received signal are A method may be used in which the contents are written in the RAM which operates based on the signal based on the signal and the contents are converted into the distance measurement value later. In addition, in this embodiment, the counter and the arithmetic unit are described separately for the sake of easy understanding of the operation, but the arithmetic unit may be provided with the function of the counter. Further, the distance calculation may be corrected by hardware or software. Further, in this example, the correction of the distance calculation is performed by subtraction, but it goes without saying that the correction by addition may be performed by delaying the start pulse in advance with a delay line or the like.

[0011]

[Effect of the device]

 As described above, according to the present invention, the start pulse, the stop pulse, or both of these signals are integrated, and the result of the distance calculation is corrected by the strength of the integrated signal, so that these signals are synchronized with the clock signal. It is possible to reduce the quantization error that is caused by the absence.

[Brief description of drawings]

FIG. 1 is a block diagram showing a laser distance measuring device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a conventional laser distance measuring device.

FIG. 3 is a diagram showing waveforms and timings of signals of respective parts.

[Explanation of symbols]

 2 Laser light 3 Start signal 4 Target 5 Reflected light from target 7 Electric signal 9 Received signal 11 Stop signal 13 Clock signal 15 Count value 18 Integrated signal 20 Hold voltage 22 Stop signal strength

Claims (1)

[Scope of utility model registration request] 1. A laser oscillator that emits a laser beam toward a target and simultaneously generates a start signal, a light receiving element that receives reflected light from the target and generates an electric signal, and an electric signal from this light receiving element is amplified. Then, an amplification unit for generating a reception signal, a comparator for generating a stop signal when the intensity of the reception signal exceeds a threshold value, a reference time generation unit for generating a clock signal, and a time difference between the start signal and the stop signal. In a laser distance measuring device comprising a calculation unit for calculating a distance to a target based on the above, a means for integrating the start signal or the stop signal or both signals, and the integrated start signal or stop signal or the both signals. Means for detecting the intensity of the signal and the result of the distance calculation according to the intensity of the integrated start signal or stop signal. A laser distance measuring device comprising: