JP4334678B2 - Distance measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a distance measuring device that measures the distance to a reflector using pulsed light, and particularly enables a highly accurate distance measurement.
[0002]
[Prior art]
In general, a distance measuring device that measures a distance to a target measures a distance by projecting a light beam, receiving reflected light that is reflected and returning, and measuring a signal delay time between transmission and reception. In the distance measurement based on the time-of-flight measurement of such a pulse signal, a large error occurs in the distance measurement due to a distance to the target or a change in received signal level (peak value) due to a change in reflection. Further, since the signal delay time is measured, a propagation delay passing through the transmission / reception circuit also occurs as a large error. Furthermore, an error occurs in the measurement distance value due to a change in environmental conditions, that is, a change in temperature or the influence of sunlight outdoors.
[0003]
Therefore, for example, Japanese Patent Application Laid-Open No. 9-318734 discloses a method of detecting the maximum value (crest value) of a received signal by a peak hold circuit and correcting the measurement distance from the relationship between the crest value and the measurement distance error. ing.
[0004]
[Problems to be solved by the invention]
Since the conventional distance measuring apparatus is configured as described above, in order to correct the measurement distance correctly, it is possible to detect the peak value of the waveform of the received signal that is transmitted and reflected and returned. Is the premise. However, in actuality, when detecting a signal that is reflected back from an object at a very short distance or an object with high reflectivity such as a reflector, the intensity of the incident light becomes very high and the received signal is saturated. Therefore, it is impossible to accurately detect the original signal peak value, and there is a problem that a large error occurs in the measurement distance.
Further, since the signal delay time is measured, there is a problem that an error is caused by the propagation delay of the electric circuit and the change of the environmental condition, for example, the temperature change or the influence of sunlight.
[0005]
The present invention has been made to solve the above-described problems, and obtains a distance measuring device capable of measuring a distance with high accuracy even when there is a change in reflected signal intensity, a temperature change, incident sunlight, and the like. For the purpose.
[0006]
[Means for Solving the Problems]
The distance measuring device according to the present invention includes a logarithmic amplifying unit that amplifies a signal received by the light receiving unit to a signal level that is not saturated so that peak detection of the signal is possible, and a signal amplified by the logarithmic amplifying unit, Linear amplifying means for amplifying with a gain capable of securing an S / N ratio in threshold detection of the signal, peak detecting means for detecting the peak value of the signal amplified by the logarithmic amplifying means, and light transmitting means for pulse light Delay time measuring means for measuring the delay time from when the signal is transmitted to the signal amplified by the linear amplifying means exceeds a predetermined threshold, and delay time measurement according to the peak value detected by the peak detecting means And a distance measuring means for correcting the delay time measured by the means and measuring the distance to the reflector according to the corrected delay time.
[0007]
The distance measuring device according to the present invention receives reference light transmitting means for transmitting pulsed light and pulse light transmitted by the light transmitting means and reflected by the reflector, and transmitted by the reference light transmitting means. A light receiving means for directly receiving the pulsed light, and a light sending means measured by the delay time measuring means according to a delay time relating to the pulse light sent by the reference light sending means measured by the delay time measuring means The error of the delay time related to the pulsed light transmitted by is erased, the delay time is corrected according to the peak value detected by the peak detecting means, and the corrected delay time is corrected. Distance measuring means for measuring the distance to the reflector.
[ 0008 ]
The distance measuring device according to the present invention has a table storing a delay time correction value corresponding to the peak value in the distance measuring means, and the delay time correction value corresponding to the peak value detected by the peak detecting means. It is extracted from the table and the delay time is corrected.
[ 0009 ]
In the distance measuring device according to the present invention, the distance measuring means corrects the distance to the reflector according to the temperature of the light receiving means detected by the temperature detecting means.
[ 0010 ]
In the distance measuring apparatus according to the present invention, the distance measuring means corrects the distance to the reflector according to the temperature of the delay time measuring means detected by the temperature detecting means.
[ 0011 ]
In the distance measuring device according to the present invention, the distance measuring unit corrects the distance to the reflector according to the change in the peak value related to the pulsed light transmitted by the reference light transmitting unit detected by the peak detecting unit. It is a thing.
[ 0012 ]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below.
Embodiment 1 FIG.
FIG. 1 is a block diagram showing a distance measuring apparatus according to Embodiment 1 of the present invention. In the figure, 1 is a transmission pulse generator for generating a transmission pulse, and 2 is an LD (laser diode) that is a light emitting element. An LD driving unit 3 is an LD that is a light emitting element, and the transmission pulse generating unit 1, the LD driving unit 2, and the LD 3 constitute light transmitting means.
4 is a reflector, and this reflector 4 is an object detected by the transmitted light. Reference numeral 5 denotes an APD (avalanche photodiode: light receiving means) that receives the reflected light. Reference numeral 6 denotes a signal amplifying unit that amplifies the signal received by the APD 5. In the signal amplifying unit 6, 6a is received by the APD 5. A logarithmic amplifying unit (logarithmic amplifying means) for amplifying the obtained signal to a signal level that is not saturated so that the peak of the signal can be detected; 6b, a signal amplified by the logarithmic amplifying unit 6a; This is a linear amplifying unit (linear amplifying means) that amplifies by a gain that can secure an SN ratio in detection.
7 is a peak detector (peak detection means) for detecting the peak value (peak value) of the signal amplified by the logarithmic amplifier 6a, and 8 is a signal amplified by the linear amplifier 6b and a predetermined threshold value. A comparator (delay time measuring means) 9 for comparison is a delay time from when the transmission pulse generator 1 generates a transmission pulse until the signal amplified by the linear amplifier 6b by the comparator 8 exceeds a predetermined threshold. A delay time measuring unit (delay time measuring means) 10 for measuring corrects the delay time measured by the delay time measuring unit 9 in accordance with the peak value detected by the peak detecting unit 7, and sets the corrected delay time to the corrected delay time. Accordingly, it is a signal processing unit (distance measuring means) that measures the distance to the reflector 4.
[ 0013 ]
Next, the operation will be described.
The distance measuring device according to the first embodiment is mounted on a car, for example, and transmits / receives near-infrared pulsed light to measure the distance to the reflector 4. As a specific example, the lateral distance to the guardrail is measured.
The transmission pulse generator 1 generates a trigger signal in the LD driver 2, the delay time measuring unit 9, and the signal processor 10. The LD driving unit 2 causes the LD 3 that is a light emitting element to emit light by the trigger signal. The driving and light emission of the LD 3 are performed at a constant cycle of, for example, every 100 μs, and transmission pulse light having a pulse width of about a dozen ns to 100 ns is transmitted.
The transmission pulse is, for example, infrared light, and the light reflected and returned from the reflector 4 is received by the APD 5 that is a light receiving element, and the APD 5 outputs a photoelectrically converted signal. The signal amplifying unit 6 amplifies the photoelectrically converted signal. At this time, according to the conventional technique, reflection from a very close distance and a reflector having a high reflectance (thing polished to a slippery) In the case of a reflector or the like, the output of the signal amplifying unit 6 is saturated and the peak value cannot be detected, so that the distance measurement cannot be obtained with high accuracy.
[ 0014 ]
Therefore, in the first embodiment, the signal amplifying unit 6 is divided in stages, and the logarithmic amplifying unit 6a first amplifies the signal photoelectrically converted by the APD 5 logarithmically. The logarithmic amplification unit 6a has a gain characteristic such that the peak value of the logarithmically amplified signal is not saturated and the peak value becomes a detectable output with high resolution. Even if a level photoelectrically converted signal is input to the logarithmic amplifier 6a, the logarithmic amplifier 6a outputs a signal that can detect a peak value with high resolution.
The linear amplification unit 6b linearly amplifies the signal logarithmically amplified by the logarithmic amplification unit 6a. The linear amplifying unit 6b has a gain characteristic that provides an output capable of securing a minimum signal-to-noise ratio when detecting the threshold value of the linearly amplified signal. Even if a gentle signal is input to the linear amplifying unit 6b, the linear amplifying unit 6b outputs a signal having a steep rise that can ensure the SN ratio when detecting the threshold value.
[ 0015 ]
The peak detector 7 detects the peak value (crest value) of the signal logarithmically amplified by the logarithmic amplifier 6a. On the other hand, the comparator 8 compares the signal linearly amplified by the linear amplifier 6b with a predetermined threshold value. Further, the delay time measuring unit 9 is configured to generate a trigger signal from the transmission pulse generating unit 1, that is, from when the LD 3 transmits pulse light until the linearly amplified signal exceeds a predetermined threshold value. Measure the delay time.
Here, as a delay time measuring method in the delay time measuring unit 9, a method of reading the voltage value by A / D conversion using a time voltage converter that converts the delay time into a voltage value by a constant conversion method, There is a method of measuring the delay time with a pulse counter.
Then, the signal processing unit 10 corrects the delay time measured by the delay time measuring unit 9 according to the peak value detected by the peak detecting unit 7, and the signal to the reflector 4 is corrected according to the corrected delay time. Measure distance.
[ 0016 ]
Hereinafter, details of the processing of the signal processing unit 10 will be described.
FIG. 2 is a conceptual diagram showing the processing of the comparator, in which SA is a standard waveform, S1 is a high level input waveform, and S2 is a low level input waveform. VTH is a threshold value, tA is a time when the standard waveform SA exceeds the threshold value VTH, and t1 and t2 are times when the input waveforms S1 and S2 exceed the threshold value VTH.
The input waveforms S1 and S2 are the waveforms of signals that are reflected from the reflector 4 at the same distance as the standard waveform SA and linearly amplified by the linear amplifier 6b. The times t1, tA, t2 when S2 exceeds the threshold value VTH are different depending on the respective peak values. Since this signal processing unit 10 calculates and determines the distance to the reflector 4 according to the time t1 or the time t2, the time t1 and t2 are not corrected so as to correspond to the time tA. Must not.
Therefore, as described above, the difference between the time tA when the standard waveform SA exceeds the threshold value VTH and the times t1 and t2 when the input waveforms S1 and S2 exceed the threshold value VTH is the difference between the respective peak values. Since it is a function, a correction value corresponding to each peak value is obtained.
FIG. 3 is a characteristic diagram showing the relationship between the peak value and the correction value, and the signal processing unit 10 stores a correction value α corresponding to the peak value P in a table based on this characteristic. Then, a correction value α corresponding to the peak value P detected by the peak detection unit 7 is extracted from the table and corrected in addition to the delay time Δt measured by the delay time measurement unit 9.
Further, according to the corrected delay time (Δt + α), the distance R to the reflector 4 is calculated by the following equation (1).
R = ((Δt + α) × c) / 2 (1)
Where c is the speed of light.
[ 0017 ]
As described above, according to the first embodiment, the logarithmic amplifier 6a having a gain characteristic that can secure a signal level that is not saturated at the time of peak detection, and the linear amplification that has a gain characteristic that can ensure an SN ratio when detecting a threshold value. 6b, the intensity of the incident light becomes very high when detecting a signal returned from an object at a very short distance or an object having a high reflectivity such as a reflector. Even if a signal with a very high level is input, the peak value of the signal can be detected accurately and at the time of detecting the threshold value can be detected accurately, depending on the detected peak value. By correcting the delay time from when the transmission pulse generator 1 generates the trigger signal until the linearly amplified signal exceeds a predetermined threshold, it is possible to accurately match the corrected delay time. Effect that is capable of measuring the distance to the painful 4 is obtained.
[ 0018 ]
Embodiment 2. FIG.
4 is a block diagram showing a distance measuring apparatus according to Embodiment 2 of the present invention. In the figure, 11 is a transmission pulse generator for generating a transmission pulse, 12 is a selector switch for switching between two systems of light transmitters, 13 Is a reference LD driving unit for measuring a reference distance provided separately from a normal distance measuring unit, and 14 is a reference LD for measuring a reference distance. Here, it is assumed that the reference LD drive unit 13 and the reference LD 14 are configured exactly the same as the LD drive unit 2 and LD3. However, the light transmitted from the normal distance measuring LD 3 is emitted in the direction of the front reflector 4, but the light from the reference LD 14 is directly incident on the APD 5. The transmission pulse generating unit 11, the changeover switch 12, the LD driving unit 2, and the LD3 constitute a light transmission means, and the transmission pulse generating unit 11, the changeover switch 12, the reference LD driving unit 13, and the reference LD14 are referred to. The light transmission means is configured.
Reference numeral 15 denotes a signal processing unit (distance measuring means). In addition to the function of the signal processing unit 10 shown in the first embodiment, the signal processing unit 15 has a pulsed light transmitted by the reference LD 14. In accordance with the delay time, the error of the delay time related to the pulse light transmitted by the LD 3 is erased.
Other configurations are the same as those in FIG.
[ 0019 ]
Next, the operation will be described.
In the second embodiment, the reference distance measurement operation is performed in addition to the normal distance measurement in the first embodiment, and the error of the normal distance measurement system is eliminated according to the reference distance measurement.
In normal distance measurement, the distance value is calculated by the operation described in the first embodiment. The distance measurement operation by the reference LD 14 is periodically performed between the normal distance measurement operations. For example, the distance measurement is performed every second by switching the changeover switch 12 instead of driving the LD3 and driving the reference LD14 to emit light.
Since the reference LD 14 is configured to be directly incident on the APD 5, the distance value obtained by the reference distance measurement operation is essentially a distance measurement corresponding to approximately 0 m.
[ 0020 ]
However, actually, the delay time difference between the generation time point of the transmission trigger signal from the transmission pulse generator 11 and the light emission time point of the reference LD 14 or the measurement time point of the delay time measurement unit 9, and further, the light reception time point and the delay time at the APD 5 Since a delay time difference from the measurement time point in the time measurement unit 9 acts as a measurement error, the distance value by the reference LD 14 does not become 0 m due to these errors. Therefore, the distance value by the reference LD 14 is used as an error value for eliminating an error during a normal distance measuring operation.
Specifically, the signal processing unit 15 calculates the difference of the delay time by the reference LD 14 from the delay time by the light emission of the LD 3, and the distance value that is the original delay time that is the amount returned by propagating through the space. Ask for. By doing this, even if the delay error that propagates through the circuit and the delay error changes due to aging, etc., the effect is the delay time during normal distance measurement operation and the delay time during reference distance measurement operation. Therefore, the error can be corrected and an accurate distance value can be obtained.
Note that an average value of a plurality of times may be adopted as the delay time during the reference distance measurement operation. As a result, variations in errors can be reduced and accuracy can be improved.
[ 0021 ]
As described above, according to the second embodiment, the reference distance measurement configuration is provided in addition to the normal distance measurement configuration, and the delay time measured in the reference distance measurement operation is provided as a function of the signal processing unit 15. Accordingly, since the error of the delay time measured in the normal distance measurement operation is deleted, the error during the normal distance measurement operation can be corrected, and an accurate distance value can be measured. An effect is obtained.
[ 0022 ]
Embodiment 3 FIG.
FIG. 5 is a block diagram showing a distance measuring apparatus according to Embodiment 3 of the present invention. In the figure, 16 is a temperature sensor (temperature detecting means) provided in the APD 5, and 17 is provided in the delay time measuring unit 9. It is a temperature sensor (temperature detection means).
Reference numeral 18 denotes a signal processing unit (distance measuring means). The function of the signal processing unit 18 is detected by the temperature sensors 16 and 17 in addition to the function of the signal processing unit 10 shown in the first embodiment. This has a function of correcting the distance to the reflector 4 in accordance with the temperatures of the APD 5 and the delay time measuring unit 9.
Other configurations are the same as those in FIG.
[ 0023 ]
Next, the operation will be described.
In the third embodiment, a temperature sensor is provided in a part sensitive to temperature, temperature fluctuation is monitored and input to the signal processing unit 18, and the calculated distance is corrected according to the temperature fluctuation. It is.
The part particularly affected by the temperature is, for example, a part of the APD 5 that is highly sensitive as a light receiving element, and a temperature sensor 16 in a thermally coupled state is provided around this part. Further, since the delay time measurement unit 9 that greatly affects the accuracy is also easily influenced by temperature, the delay time measurement unit 9 includes, for example, an analog element of a time voltage conversion unit, a clock oscillation unit of a pulse counter unit, and a delay element. A temperature sensor 17 in a state of being thermally coupled to a time delay adjusting unit such as the above is installed.
The detection results of the temperature sensors 16 and 17 are input to the signal processing unit 18.
6 and 7 are characteristic diagrams showing the relationship between the temperature fluctuation and the distance error. In the signal processing unit 18, as shown in FIGS. 6 and 7, the relationship between the temperature and the distance error is measured in advance. It is stored as a table value, and an accurate distance value is calculated by correcting the distance error from the detected temperature during actual distance measurement.
Note that the configurations of the temperature sensors 16 and 17 and the signal processing unit 18 according to the third embodiment may be applied to the configuration of the second embodiment.
[ 0024 ]
As described above, according to the third embodiment, the temperature sensors 16 and 17 are provided in the APD 5 and the delay time measurement unit 9 that are sensitive to temperature, and the signal processing unit 18 responds to the detected temperature. Thus, the distance error is extracted from the table, and the calculated distance is corrected according to the distance error, so that an accurate distance value can be measured even if the ambient temperature varies.
[ 0025 ]
Embodiment 4 FIG.
In the fourth embodiment, the signal processing unit 15 corrects the distance to the reflector 4 in accordance with the change in the peak value related to the pulsed light transmitted by the reference LD 14 detected by the peak detection unit 7. Is.
Other configurations are the same as those in FIG.
[ 0026 ]
Next, the operation will be described.
One of the factors that cause errors in distance measurement is a change in received signal due to the influence of sunlight. In the component of sunlight, the component of the emission frequency used in the distance measuring device is included, and the more sensitive the distance measuring device, the more influenced by the background light other than the signal light, The reception level at the time of normal distance measurement changes, and it is generated as an error as it is.
In the fourth embodiment, the error is corrected using the fact that the influence of the same sunlight is also generated during the reference distance measurement operation.
FIG. 8 is a characteristic diagram showing the relationship between the peak value and distance error during reference distance measurement. As shown in FIG. 8, the relationship between the change in peak value during reference distance measurement operation and the distance error at that time is shown. It is measured in advance and stored as a table value, and an accurate distance value is calculated by correcting a distance error from a change in peak value at the time of measuring a reference distance during actual distance measurement. When there is no influence of sunlight, the peak value at the time of measuring the reference distance does not change and is at a constant level.
[ 0027 ]
As described above, according to the fourth embodiment, in the signal processing unit 15, depending on the change in the peak value related to the pulsed light transmitted by the reference LD 14 detected by the peak detection unit 7, Since the distance is corrected, an error is not included in the normal distance measurement due to the influence of background light other than the pulsed light, and an effect that an accurate distance value can be measured is obtained.
It should be noted that the distance measuring devices shown in the above first to fourth embodiments are not limited to the illustrated examples described above, and various changes can be made without departing from the scope of the embodiments. Needless to say.
[ 0028 ]
【The invention's effect】
As described above, according to the present invention, the logarithmic amplifying means for amplifying the signal received by the light receiving means to a signal level that is not saturated so that the peak of the signal can be detected, and the signal amplified by the logarithmic amplifying means. Linear amplifying means for amplifying the signal with a gain such that an S / N ratio can be secured in threshold detection of the signal, a peak detecting means for detecting a peak value of the signal amplified by the logarithmic amplifying means, and a light transmitting means Delay time measuring means for measuring the delay time from when the pulse light is transmitted until the signal amplified by the linear amplifying means exceeds a predetermined threshold, and delay according to the peak value detected by the peak detecting means Distance measuring means for correcting the delay time measured by the time measuring means and measuring the distance to the reflector according to the corrected delay time is provided. Therefore, when detecting a signal that is reflected back from an object at a very close distance or an object having a high reflectivity such as a reflector, the intensity of incident light is very high and the light receiving means is very high. Even if a level signal is input, the peak value of the signal can be detected accurately and at the time of threshold detection, and the delay time can be corrected according to the detected peak value. By doing so, the effect of being able to accurately measure the distance to the reflector according to the corrected delay time is obtained.
[ 0029 ]
According to this invention, the reference light transmitting means for transmitting the pulsed light, and the pulse light transmitted by the light transmitting means and reflected by the reflector, and the pulse transmitted by the reference light transmitting means are received. Light is transmitted by a light receiving unit that directly receives light and a light transmitting unit that is measured by the delay time measuring unit according to a delay time related to the pulse light transmitted by the reference light transmitting unit that is measured by the delay time measuring unit. The error of the delay time related to the pulsed light is erased, the delay time is corrected according to the peak value detected by the peak detecting means, and the reflector is corrected according to the corrected delay time. Because it is configured to include a distance measurement means that measures the distance of the distance, it is necessary to correct errors during normal distance measurement operations due to propagation delay and aging of the electrical circuit Can effect capable of measuring an accurate distance value is obtained.
[ 0030 ]
According to the present invention, the distance measuring means has a table storing a delay time correction value corresponding to the peak value, and the delay time correction value corresponding to the peak value detected by the peak detecting means is extracted from the table. Thus, since the delay time is corrected, it is possible to extract the delay time correction value corresponding to the peak value using the table.
[ 0031 ]
According to the present invention, since the distance measuring unit is configured to correct the distance to the reflector according to the temperature of the light receiving unit detected by the temperature detecting unit, an accurate distance value can be obtained even if the ambient temperature varies. The effect that can be measured is obtained.
[ 0032 ]
According to the present invention, the distance measuring unit is configured to correct the distance to the reflector according to the temperature of the delay time measuring unit detected by the temperature detecting unit, so that it is accurate even if the ambient temperature varies. The effect that the distance value can be measured is obtained.
[ 0033 ]
According to this invention, the distance measuring means is configured to correct the distance to the reflector according to the change in the peak value related to the pulsed light transmitted by the reference light transmitting means detected by the peak detecting means. Therefore, an error is not included in normal distance measurement due to the influence of background light other than pulse light, and an effect that an accurate distance value can be measured is obtained.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a distance measuring apparatus according to Embodiment 1 of the present invention.
FIG. 2 is a conceptual diagram showing processing of a comparator.
FIG. 3 is a characteristic diagram showing a relationship between a peak value and a correction value.
FIG. 4 is a block diagram showing a distance measuring apparatus according to Embodiment 2 of the present invention.
FIG. 5 is a block diagram showing a distance measuring apparatus according to Embodiment 3 of the present invention.
FIG. 6 is a characteristic diagram showing the relationship between temperature variation and distance error.
FIG. 7 is a characteristic diagram showing the relationship between temperature variation and distance error.
FIG. 8 is a characteristic diagram showing a relationship between a peak value and a distance error when measuring a reference distance.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Transmission pulse generation part (light transmission means), 2 LD drive part (light transmission means), 3 LD (light transmission means), 4 reflector, 5 APD (light reception means), 6a Logarithmic amplification part (logarithmic amplification means), 6b Linear amplification unit (linear amplification unit), 7 Peak detection unit (peak detection unit), 8 Comparator (delay time measurement unit), 9 Delay time measurement unit (delay time measurement unit) 10, 15, 18 Signal processing unit ( Distance measurement means), 11 transmission pulse generator (light transmission means, reference light transmission means), 12 changeover switch (light transmission means, reference light transmission means), 13 reference LD drive section (reference light transmission means), 14 Reference LD (light transmission means for reference), 16, 17 Temperature sensor (temperature detection means).

Claims (6)

  A light transmitting means for transmitting pulse light, a light receiving means for receiving pulse light reflected by the reflector, and a signal level at which the signal received by the light receiving means is not saturated so that the peak of the signal can be detected. A logarithmic amplifying means for amplifying the signal, a linear amplifying means for amplifying the signal amplified by the logarithmic amplifying means with a gain such that an S / N ratio can be ensured in threshold detection of the signal, and A peak detecting means for detecting a peak value of the received signal, and a delay time from when the light transmitting means transmits pulse light to when the signal amplified by the linear amplifying means exceeds a predetermined threshold The delay time measured by the delay time measuring means is corrected in accordance with the peak value detected by the peak detecting means and the delay time measuring means for correcting the delay time. Distance measuring apparatus and a distance measuring means for measuring a distance to the reflector in accordance with the delay time.   Light transmitting means for transmitting pulsed light, reference light transmitting means for transmitting pulsed light, pulse light transmitted by the light transmitting means and reflected by the reflector, and receiving the reference light A light receiving means for directly receiving the pulsed light transmitted by the means, a logarithmic amplifying means for amplifying the signal received by the light receiving means to a signal level that is not saturated so that peak detection of the signal is possible, and the logarithm A linear amplifying means for amplifying the signal amplified by the amplifying means with a gain such that an S / N ratio can be secured in threshold detection of the signal, and a peak for detecting a peak value of the signal amplified by the logarithmic amplifying means. A delay for measuring a delay time between the detection means and the light transmission means transmitting the pulse light until the signal amplified by the linear amplification means exceeds a predetermined threshold Light is transmitted by the light transmitting means measured by the delay time measuring means according to the delay time relating to the pulse light transmitted by the reference light transmitting means measured by the delay time measuring means. The error of the delay time related to the pulsed light is erased, the delay time from which the error is erased is corrected according to the peak value detected by the peak detecting means, and the reflector is corrected according to the corrected delay time. A distance measuring device comprising distance measuring means for measuring the distance to The distance measuring unit has a table storing a delay time correction value corresponding to the peak value, and the delay time correction value corresponding to the peak value detected by the peak detection unit is extracted from the table to delay time. The distance measuring device according to claim 1 or 2, wherein the distance is corrected. Comprising a temperature detecting means for detecting the temperature of the light receiving means, the distance measuring means, according to claim 1, characterized in that to correct the distance to the reflector in accordance with the detected temperature of the said light receiving means by said temperature detecting means The distance measuring device according to claim 3 . A temperature detection means for detecting the temperature of the delay time measurement means is provided, and the distance measurement means corrects the distance to the reflector according to the temperature of the delay time measurement means detected by the temperature detection means. The distance measuring device according to any one of claims 1 to 3 .   The distance measuring means corrects the distance to the reflector in accordance with a change in peak value relating to the pulsed light transmitted by the reference light transmitting means detected by the peak detecting means. Distance measuring device.

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