JPH07306266A - Distance measuring equipment - Google Patents

Abstract

PURPOSE:To provide a distance measuring equipment having high distance accuracy. CONSTITUTION:A pulse light emitted from a light emitting element 10 is received by a light receiving element 20 for monitoring and a light receiving element 30 for detection. The light receiving element 20 generates a pulse voltage signal 131 having amplitude variable depending on the intensity of received pulse light. A discriminating means 60 receives the pulse voltage signal 131 and produces a digital pulse signal 135. Similarly, a digital pulse signal 136 is outputted from the light receiving element 30 through a discriminating means 80. The signals 135, 136 are fed to a time voltage converting means 90 which produces an analog voltage signal 139 having magnitude variable at a constant rate during an interval after the input of the pulse signal 135 before the input of the pulse signal 136. An operating means 110 calculates the distance up to a target based on the analog voltage signal 139.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring device which measures a distance to a target by emitting pulsed light to the target and measuring the time until the reflected light returns.

[0002]

2. Description of the Related Art Conventionally, as a technique in such a field,
JP-A-4-12289 is known. The configuration of the conventional distance measuring device described in this publication is shown in the block diagram of FIG. From the figure, in the transmission unit 200, the control unit 210
The laser diode 201 is caused to emit light in accordance with the light emission signal from, and laser light is emitted toward the target object. The laser light is reflected by the target object and is received by the photodiode 221 of the receiver 220. The light emission timing signal output from the transmission unit 200 in synchronization with the emission timing of the laser diode 201 and the reflection signal output from the reception unit 220 in synchronization with the light reception timing of the photodiode 221 are provided to the time measurement unit 230. Time measuring unit 230
Then, a time difference pulse signal corresponding to the time difference between these signals is generated, and the pulse width of this time difference pulse signal is counted by the counter 211 of the control unit 210. The control unit 210 performs calculation based on the count value of the counter 211 and detects the distance to the target object.

[0003]

However, since the distance accuracy is determined by the clock cycle of the counter 211 in the conventional distance measuring device, there is a problem that improvement in the distance accuracy cannot be expected.

An object of the present invention is to solve such a problem and to provide a distance measuring device with high distance accuracy.

[0005]

In order to solve the above-mentioned problems, a first distance measuring device of the present invention comprises (a) a light emitting element for emitting pulsed light, and (b) a pulsed light emitted from the light emitting element. A light receiving element for monitoring, which receives a part of the received light and outputs an analog pulse voltage signal having an amplitude according to the received light intensity,
(C) A light receiving element for detection that receives light in which another part of the pulsed light emitted from the light emitting element is reflected by a predetermined target object, and outputs an analog pulse voltage signal having an amplitude according to the light receiving intensity; d) A first discriminating means for inputting the signal output from the light receiving element for monitoring and outputting a digital pulse signal with reduced time jitter, and (e) inputting the signal output from the light receiving element for detection, Second discrimination means for outputting a digital pulse signal with reduced time jitter;
(F) The first signal and the second signal output from the first discriminating means.
Analog whose voltage value increases at a constant ratio during the period from the input of the pulse of the first signal to the input of the pulse of the second signal after the input of the second signal output from the discriminating means Time-voltage converting means for outputting a voltage signal, and (g)
The analog voltage signal output from the time-voltage conversion means is input, and the target voltage is increased based on the increase amount of the voltage value from the input of the pulse of the first signal to the input of the pulse of the second signal. The first discriminating means and the second discriminating means provide a signal obtained by delaying the input signals to the discriminating means by a predetermined time and a signal obtained by attenuating the amplitude of the input signal. It subtracts and outputs a digital pulse signal which gives a pulse when the subtracted value reaches a predetermined value.

A second distance measuring device of the present invention is the same as the first distance measuring device of the present invention, and additionally, a correction signal for applying a first correction signal and a second correction signal to the time-voltage converting means. An output means is provided, and the first correction signal outputs the first pulse and the second pulse at a predetermined time interval before the first signal is pulsed or after the second signal is pulsed. The digital pulse signal to be given, the second
Of the first correction signal and the second pulse to the first correction signal after the first pulse is applied to the first correction signal and before the second pulse is applied to the first correction signal. Is a digital pulse signal that gives a fourth pulse after being given, and a time interval (t2) from when the first pulse is given to when the third pulse is given and after the second pulse is given. The time interval (t3) until the pulse No. 4 is given is different, and the time-voltage conversion means uses the first signal, the second signal, the first correction signal, and the second signal.
The correction signal of the first signal is input, the period from the input of the pulse of the first signal to the input of the pulse of the second signal,
The voltage value increases at a constant rate during the period from the input of the pulse of 3 to the input of the third pulse, and from the input of the second pulse to the input of the fourth pulse. An analog voltage signal is output, and the arithmetic means analyzes the input analog voltage signal and increases the voltage value from the input of the pulse of the first signal to the input of the pulse of the second signal. (V1), the amount of increase in voltage value (V2) from the input of the first pulse to the input of the third pulse, and the input of the second pulse to the input of the fourth pulse. The time interval (t1) from the input of the pulse of the first signal to the input of the pulse of the second signal is detected as t1 = (t3 -T2) x (V1-V2) / (V3-V
2) The distance to the target object is calculated by obtaining it from + t2.

[0007]

According to the first distance measuring apparatus of the present invention, a part of the pulsed light emitted from the light emitting element is received by the monitor light receiving element. Further, another part of the pulsed light is emitted toward the target object, and the light reflected by the target object is received by the detection light receiving element. The monitor light-receiving element generates an analog pulse voltage signal having an amplitude according to the light intensity of the received pulsed light, and the voltage signal is given to the first discriminating means. First
In the discriminating means, the digital pulse signal in which the time jitter of the input signal is reduced is generated and output. Specifically, a signal obtained by delaying the input signal for a predetermined time and a signal obtained by attenuating the amplitude of the input signal are generated, and the signal obtained by attenuating the amplitude is subtracted from the signal delayed by the predetermined time. It generates and outputs a digital pulse signal that gives a pulse when it reaches a predetermined value. Similarly, an analog pulse voltage signal is applied from the detection light receiving element to the second discriminating means, and a digital pulse signal with reduced time jitter is output.

The first signal outputted from the first discriminating means and the second signal outputted from the second discriminating means are given to the time-voltage converting means, and after the pulse of the first signal is inputted. An analog voltage signal whose voltage value increases at a constant rate is output during the period until the pulse of the second signal is input. This analog voltage signal is given to the calculating means and
The distance to the target object is calculated based on the increase amount of the voltage value after the pulse of the signal is input until the pulse of the second signal is input.

Further, according to the second distance measuring apparatus of the present invention, the first correction signal and the second correction signal output from the correction signal output means are time-voltage converted together with the first and second signals. Given to the means. By inputting these correction signals, the time-voltage converting means receives the first pulse from the time when the pulse of the first signal is input until the pulse of the second signal is input, and then the third pulse from the time when the first pulse is input. The analog voltage signal whose voltage value increases at a constant ratio is output during the period from the input of the second pulse and the period from the input of the second pulse to the input of the fourth pulse.

In the calculating means, the increase amount of the voltage value from the input of the pulse of the first signal to the input of the pulse of the second signal is calculated by the third pulse after the input of the first pulse. The distance to the target object is calculated while correcting with the increase amount of the voltage value until is input and the increase amount of the voltage value from the input of the second pulse to the input of the fourth pulse. To be done.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram showing the configuration of the distance measuring device 1 according to the present embodiment. As shown in FIG. 1, the distance measuring device 1 according to the present embodiment includes a pulse laser 10 that emits a laser beam, a monitor sensor 20 that receives a part of the laser beam and monitors the emission timing of the laser beam, and The other part is provided with a detection sensor 30 that receives the light reflected by the target object. Further, a pulse laser oscillation circuit 40 for giving a pulse laser emission signal to the pulse laser 10
And an amplifier 50 for amplifying the output of the monitor sensor 20.
And a CFD (Constant Fraction for monitoring) for reducing the time jitter of the light emission pulse signal amplified by the amplifier 50.
Discriminator) circuit 60.

Further, an amplifier 70 for amplifying the output of the detection sensor 30 and a detection CFD circuit 80 for reducing the time jitter of the detection pulse signal amplified by the amplifier 70.
And the output of the CFD circuit 60 (start signal) and CF
Each of the D circuits 80 is provided with a TAC (Time-to-Amplitude Converter) circuit 90 which inputs an output (stop signal) and outputs an analog voltage signal proportional to a pulse interval. Furthermore, A for converting the analog voltage signal output from the TAC circuit 90 into a digital voltage signal
A DC circuit 100, a control circuit 110 that inputs a digital voltage signal output from the ADC circuit 100 to calculate a distance to a target object, and an internal sequence generation circuit 120 that generates a reference sequence inside the apparatus are provided. There is.

A light projecting lens 11 for irradiating a laser beam toward a target object is provided on the front surface of the pulse laser 10, and a light receiving lens 31 for converging light reflected by the target object is provided on the front surface of the detection sensor 30. Bandpass filters 32 that remove ambient light are arranged.

The distance measuring device 1 of this embodiment has an appearance as shown in the perspective view of FIG. As shown in the figure, this device is housed in a rectangular parallelepiped case 150.
An emission window 151 for emitting laser light and an incident window 152 for entering the laser light reflected by the target object are provided on the front surface of 50. Inside the case 150, the front regions 150a, 15
It is divided into three areas, 0b and a rear area 150c. Then, in the front region 150a behind the emission window 151, the printed board 16 in which the pulse laser 10, the light projecting lens 11, the monitor sensor 20, and the pulse laser oscillation circuit 40 are incorporated.
0 and 0 are arranged at predetermined positions. In addition, the entrance window 15
In the front region 150b at the rear of the second position, the light detection sensor 30, the light receiving lens 31, the band pass filter 32, and the amplifier 70 are provided.
And a printed board 161 in which are mounted at a predetermined position. Further, in the rear area 150c, a printed board 162 in which the CFD circuits 60 and 80, the TAC circuit 90 and the like are incorporated and a printed board 163 in which the control circuit 110 is incorporated are arranged in two stages.

Next, the operation of this embodiment will be described with reference to the block diagram of FIG. 1 and the timing waveform diagram of FIG. The pulsed laser light emission signal 130 (FIG. 3A) output from the internal sequence generation circuit 120 is input to the pulsed laser oscillation circuit 40 to cause the pulsed laser 10 to emit light. Most of the emitted laser light is emitted toward the target through the light projecting lens 11. A part of the emitted laser light is received by the monitor sensor 20, and an analog pulse voltage signal having an amplitude according to the received light intensity is output.
The analog pulse voltage signal is amplified by the amplifier 50, and then the CFD is output as the light emission pulse signal 131 (FIG. 3B).
Provided to the circuit 60.

The laser light reflected by the target object is received by the light receiving lens 3
The light is condensed at 1, and is received by the detection sensor 30 through the bandpass filter 32. Since the bandpass filter 32 functions to pass only light having the same wavelength as the laser light, most of the disturbance light is removed by the bandpass filter 32 and is not given to the detection sensor 30.
The detection sensor 30 outputs an analog pulse voltage signal having an amplitude according to the received light intensity. The analog pulse voltage signal is amplified by the amplifier 70 and then given to the CFD circuit 80 as the detection pulse signal 132 (FIG. 3C).

The CFD circuits 60 and 80 are turned on in accordance with the pulse rising timing of the pulse laser emission signal 130.
The gate signal 133 (FIG. 3 (d)) is provided which is in the N state and holds this state for a period corresponding to the maximum measurement distance of the device. When the gate signal 133 is turned on, the CFD circuits 60 and 80 become operable, and the reflected light is detected only during this period.

When the distance to the target is less than the maximum distance measured by the apparatus, the start signal 135 (FIG. 3 (e)) and the stop signal 136 from the CFD circuits 60 and 80, respectively.
(FIG. 3 (f)) is output and given to the TAC circuit 90. These signals 135 and 136 are the light emission pulse signal 1
31 and the detection pulse signal 132 have reduced time jitter. Further, the TAC circuit 90 receives the correction start signal 137 (see FIG. 3) from the internal sequence circuit 120.
(G)) and the correction stop signal 138 (FIG. 3 (h)) are also given. The correction start signal 137 is a digital pulse signal that gives the first pulse and the second pulse at a predetermined time interval after the pulse is given to the stop signal 136. Further, the correction stop signal 138 gives the third pulse after the first pulse is given to the correction start signal 137 and before the second pulse is given, and the correction stop signal 138 is given a second pulse to the correction start signal 137. Is a digital pulse signal which gives a fourth pulse after the pulse of. The time interval between the first pulse and the third pulse (t _ST1 ) and the time interval between the second pulse and the fourth pulse (t _ST2 ) are known and the time interval (t _ST1 ).
The time interval (t _ST2 ) is adjusted to be wider.

In the TAC circuit 90, the start signal 135
Period from the input of the pulse of the stop signal 136 to the input of the pulse of the stop signal 136, the period from the input of the first pulse to the input of the third pulse, and the input of the second pulse The analog voltage signal 139 (FIG. 3 (i)) whose voltage value increases at a constant rate is generated during the period from to the input of the fourth pulse. The analog voltage signal 139 is input to the ADC circuit 100, and A / D conversion is performed in synchronization with the AD timing signal 140 (FIG. 3 (j)) given from the internal sequence generation circuit 120. By this A / D conversion, a high resolution digital voltage signal 141 (FIG. 3 (k)) is generated, and the control circuit 11
Given to 0.

In the control circuit 110, the input digital voltage signal 141 is analyzed, and an increase amount (V _D ) of the voltage value from the input of the pulse of the start signal 135 to the input of the pulse of the stop signal 136 is determined. , The amount of increase (V _ST1 ) in the voltage value from the input of the first pulse to the input of the third pulse, and from the input of the second pulse to the input of the fourth pulse The increase amount of the voltage value (V _ST2 ) is detected. Then, the calculation by the following calculation formula (Formula 1) is performed, and the time interval (t _D ) from the input of the pulse of the start signal 135 to the input of the pulse of the stop signal 136 is obtained.

T _D = (t _ST2 −t _ST1 ) × (V _D −V _ST1 ) / (V _ST2 −V _ST1 ) + t
_ST1 (Equation 1) The TAC circuit 9 is calculated by calculating the distance to the target object based on the time interval (t _D ) thus obtained.
It is possible to suppress the baseline fluctuation in the low frequency region and the ramp waveform gradient fluctuation due to the external temperature fluctuation that occurs at 0, and to perform stable distance measurement in a short time.

If the distance to the target is longer than the maximum measured distance of the apparatus, the undetected signal 134 is given from the CFD circuit 80 to the control circuit 110, and the measurement of the distance to the target by the apparatus is completed. .

In the control circuit 110, in addition to the above calculation, the error signal 14 output from the pulse laser oscillation circuit 40 is output.
2 and the undetected signal 134 output from the CFD circuit 80 are input to manage the operation state of the apparatus. Further, the control circuit 110 controls the interface with an external device.

The distance measuring device 1 of this embodiment measures the distance to the target object and the time interval until the laser light emitted from the pulse laser 10 is reflected by the target object and returns to the detection sensor 30. The CFD circuits 60 and 80 and the TAC circuit 90 are combined to configure the circuit in order to improve the accuracy of the measurement and shorten the measurement time. In other words, in the same distance measurement, the analog pulse voltage signal (the output signal from the monitor sensor 20 and the detection sensor 30) fluctuates due to the fluctuation of the output of the pulse laser 10 and the fluctuation of the light amount due to the difference in the reflectance of the target object. By passing these analog pulse voltage signals through the CFD circuits 60 and 80, digital (trigger) signals that are not affected by fluctuations (without time jitter) are generated. This digital signal is T
Since it is given to the AC circuit 90, the distance to the target can be measured with high accuracy.

Further, the distance measuring device 1 of the present embodiment uses the actual measurement signals (start signal 135, stop signal 13).
6) and a correction signal having a known pulse interval (correction start signal 137, correction stop signal 138)
The feature is that the distance to the target object is calculated based on the three types of voltage increase amounts output from the TAC circuit 90, which are continuously given to the circuit 90. By performing the calculation based on the plurality of voltage increase amounts in this way, T
It is possible to suppress low frequency fluctuations of the AC circuit 90 and perform stable distance measurement.

Here, in order to exert the above-mentioned characteristics of the preceding stage (combination of the CFD circuits 60 and 80 and the TAC circuit 90 can improve the accuracy of measurement, etc.), TA
A correction signal (correction start signal 137,
It is not always necessary to give the correction stop signal 138) to perform the correction process. That is, when the distance measuring device 1 is used in an environment where temperature fluctuation is unlikely to occur, the TAC circuit 90
There is little need to consider the correction of the low frequency fluctuation of the above, and in such a case, the correction signal may not be given to the TAC circuit 90. When the correction signal is not given, the control circuit 110 detects only the increase amount (V _D ) of the voltage value of the analog voltage signal 139, and the distance to the target object is calculated based on this increase amount (V _D ). It

Next, the CFD circuit used in this embodiment will be described. The CFD circuit is a circuit that generates a constant timing pulse (digital) for a waveform having a constant rising edge (leading edge) time of an analog input signal and different amplitude voltages. FIG. 4A shows an equivalent circuit block, and FIGS. 4B to 4F show waveforms at respective parts. The operation of the CFD circuit will be described with reference to these figures. Has a constant rise time ( _tr ) and an amplitude voltage (V)
Of different analog input signals A (see FIG. 4B) are CF
When input to the D circuit, the input signal A is given to the attenuation circuit 170 and the delay circuit 171. The attenuator circuit 170 produces a signal B (see FIG. 4C) in which the amplitude of the input signal A is attenuated to 1 / n. In the delay circuit 171, the input signal A
Is delayed by t _d to generate a signal C (see FIG. 4D). These two signals B and C are the differential amplifier 172.
Signal D obtained by subtracting the signal B from the signal C (see FIG. 4E) is generated. The signal D is the ADC circuit 17
3 and a point a crossing zero (ground potential) is detected. Then, the digital pulse signal E which rises to the ON state at the detection timing of the point a (see FIG. 4 (f)) is output.

Here, the time at which the point a occurs is t _d + t _r
Since it can be expressed as / n, it is understood that the digital pulse signal E is a signal irrelevant to the amplitude voltage (V) of the analog input signal A. This means that the analog input signal A
If the rise time (t _r ) of the signal does not fluctuate, it means that the digital pulse signal E is a signal without time fluctuation even if the amplitude voltage (V) fluctuates.

In the distance measuring apparatus 1 of this embodiment shown in FIG. 1, the influence of the fluctuation of the output of the pulse laser 10 and the fluctuation of the light quantity due to the difference in the reflectance of the target is the light emission pulse signal output from the amplifiers 50 and 70. 131 and detection pulse signal 132
Appears in the waveform. The effect of this variation is that the amplifiers 50, 70
It is possible to obtain digital pulse signals (start signal 135, stop signal 136) which are eliminated by providing the CFD circuits 60 and 80 in the subsequent stage and which are eliminated.

Although the technical field is different from that of this embodiment, CF is used.
A conventional technique of a circuit in which a D circuit and a TAC circuit are combined is disclosed in the document of Japanese Patent Application Laid-Open No. 61-266942.

Next, a distance measuring device 2 according to another embodiment of the present invention will be described with reference to the block diagram of FIG. 5 and the timing waveform diagram of FIG. The distance measuring device 2 according to this embodiment includes AGC circuits 180 and 181 that generate a constant pulse waveform from a signal including a fluctuation in output of pulsed laser light and a fluctuation in light amount due to a difference in reflectance of a target object at the same distance.
LED that detects the rising edge of a pulse waveform signal at a constant voltage level and generates a timing pulse with little time jitter
It is characterized in that highly accurate distance measurement can be performed by combining the circuits 182 and 183.

Here, the distance measuring device 2 shown in FIG.
The difference from the distance measuring device 1 is that AGC circuits 180 and 181 are provided instead of the amplifiers 50 and 70, and the CFD circuit 6 is provided.
The point is that LED circuits 182 and 183 are provided instead of 0 and 80. Therefore, the distance measuring device 2 operates as follows.

First, the pulsed laser emission signal 130 (FIG. 6A) output from the internal sequence generation circuit 120.
Is input to the pulse laser oscillation circuit 40 to cause the pulse laser 10 to emit light. Most of the emitted laser light is emitted toward the target through the light projecting lens 11. A part of the emitted laser light is received by the monitor sensor 20,
An analog pulse voltage signal (FIG. 6B) having an amplitude according to the received light intensity is output. The analog pulse voltage signal is controlled by the AGC circuit 180 so that the voltage amplitude becomes constant, and the light emission pulse signal 131 (FIG. 6C) is LE.
It is given to the D circuit 182. The LED circuit 182 detects the rising edge of the light emission pulse signal 131 at a constant voltage level, and outputs a digital pulse start signal 135 (FIG. 6 (d)) in which time fluctuation is suppressed.

The laser light reflected by the target object is received by the light receiving lens 3
The light is condensed at 1, and is received by the detection sensor 30 through the bandpass filter 32. The detection sensor 30 outputs an analog pulse voltage signal (FIG. 6E) having an amplitude according to the received light intensity. Analog pulse voltage signal is A
The voltage amplitude is controlled to be constant by the GC circuit 181, and the LED is used as the detection pulse signal 132 (FIG. 6 (f)).
Provided to circuit 183. The LED circuit 183 detects the rising edge of the detection pulse signal 132 at a constant voltage level,
Digital pulse stop signal 13 with suppressed time fluctuation
6 (FIG. 6 (g)) is output.

Start signal 135 and stop signal 1
36 is input to the TAC circuit 90, and a start signal 135
The analog voltage signal 139 that increases the voltage in proportion to time from the leading edge of the stop signal 136 and stops the increase of the voltage by the leading edge of the stop signal 136.
(FIG. 6 (h)) is generated. The generated analog voltage signal 139 is input to the ADC circuit 100, and A / D conversion is performed in synchronization with the AD timing signal 140 (FIG. 6 (i)) given from the internal sequence generation circuit 120. By this A / D conversion, a high resolution digital voltage signal 141 (FIG. 6 (j)) is generated, and the control circuit 11
Given to 0. The control circuit 110 analyzes the input digital voltage signal 141 and calculates the distance to the target.

As described above, by measuring the time difference (Δt) proportional to the distance (l) as the analog voltage (V), highly accurate distance measurement can be performed. Further, by using the AGC circuit 181 and the LED circuit 183, the detection sensor 30 can detect weak light. For this reason,
Even if the target is a long distance and the reflected light is very weak, the distance can be easily measured.

The present invention is not limited to the above embodiment, but various modifications can be made. For example, in this embodiment, after the stop signal is pulsed, the correction start signal and the correction stop signal are pulsed (first pulse to
Although the fourth pulse) is given, the pulses may be given to the correction start signal and the correction stop signal before the start signal is given a pulse.

In the distance measuring device 2, the TAC circuit 9
Although only the start signal 135 and the stop signal 136 are input to 0, the correction start signal 137 and the correction stop signal 138 are input to the TAC circuit 90 to change the output voltage of the TAC circuit 90 due to the change of the external temperature. May be corrected.

[0039]

As described in detail above, in the distance measuring device of the present invention, the digital pulse signal which is not affected by the output fluctuation of the input signal is generated by the first discriminating means and the second discriminating means, This digital pulse signal is input to the time-voltage conversion means. Therefore, even if the signals output from the monitor light receiving element and the detection light receiving element fluctuate due to the output fluctuations of the light emitting element and the output fluctuations due to the difference in the reflectance of the target object, the voltage signal generated by the time-voltage conversion means. Is not affected by this output fluctuation. Therefore, the calculation means can calculate the distance to the target object with high accuracy based on the voltage signal generated by the time-voltage conversion means.

Further, according to the present invention, an analog voltage signal proportional to the time from the emission of the pulsed light to the reception of the pulsed light is generated by the time-voltage conversion means, and the distance is calculated from this analog voltage signal. Higher distance accuracy can be obtained as compared with the conventional technique that counts time and calculates distance.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a distance measuring device according to an embodiment.

FIG. 2 is a perspective view showing the outer appearance of the distance measuring device according to the present embodiment.

FIG. 3 is a timing waveform chart of the distance measuring device according to the present embodiment.

FIG. 4 is an equivalent circuit block diagram and a timing waveform diagram of a CFD circuit.

FIG. 5 is a block diagram showing a configuration of a distance measuring device according to another embodiment.

FIG. 6 is a timing waveform chart of a distance measuring device according to another embodiment.

FIG. 7 is a block diagram showing a configuration of a conventional distance measuring device.

[Explanation of symbols]

1, 2 ... Distance measuring device, 10 ... Pulse laser, 11 ... Projection lens, 20 ... Monitor sensor, 30 ... Detection sensor, 31 ... Light receiving lens, 32 ... Bandpass filter, 4
0 ... Pulse laser oscillation circuit, 50, 70 ... Amplifier, 6
0,80 ... CFD circuit, 90 ... TAC circuit, 100 ... A
DC circuit, 110 ... Control circuit, 120 ... Internal sequence generation circuit, 130 ... Pulse laser emission signal, 131 ... Emission pulse signal, 132 ... Detection pulse signal, 133 ... Gate signal, 134 ... Undetected signal, 135 ... Start signal,
136 ... Stop signal, 137 ... Correction start signal,
138 ... Compensation stop signal, 139 ... Analog voltage signal, 140 ... AD timing signal, 141 ... Digital voltage signal, 142 ... Error signal, 150 ... Case, 15
DESCRIPTION OF SYMBOLS 1 ... Emission window, 152 ... Incident window, 160-163 ... Printed board, 170 ... Attenuation circuit, 171 ... Delay circuit, 172 ...
Differential amplifier, 173 ... ADC circuit, 180, 181 ... A
GC circuit, 182, 183 ... LED circuit.

Claims (2)

[Claims] 1. A light emitting element that emits pulsed light, a light receiving element for monitoring that receives a part of the pulsed light emitted from the light emitting element, and outputs an analog pulse voltage signal having an amplitude according to the light receiving intensity. Another part of the pulsed light emitted from the light emitting element receives the light reflected by a predetermined target object, and a detection light receiving element for outputting an analog pulse voltage signal having an amplitude according to the received light intensity; A first discriminator for inputting a signal output from the light receiving element and outputting a digital pulse signal with reduced time jitter, and a signal output from the detection light receiving element are input to reduce the time jitter. Second discrimination means for outputting a digital pulse signal, a first signal outputted from the first discrimination means and a second signal outputted from the second discrimination means are inputted, and the second discrimination means is inputted. Time-voltage converting means for outputting an analog voltage signal whose voltage value increases at a constant rate during the period from the input of the pulse of the signal to the input of the pulse of the second signal, and the time-voltage converting means. To the target based on the amount of increase in the voltage value from the input of the pulse of the first signal to the input of the pulse of the second signal. Calculating means for calculating the first discriminating means and the second discriminating means, wherein the signals obtained by delaying the input signals to the discriminating means by a predetermined time are attenuated in amplitude of the input signals. Subtract
A distance measuring device which outputs a digital pulse signal which gives a pulse when the subtracted value reaches a predetermined value. 2. A correction signal output means for applying a first correction signal and a second correction signal to the time-voltage conversion means, wherein the first correction signal is before the pulse is applied to the first signal. Alternatively, it is a digital pulse signal that gives the first pulse and the second pulse at a predetermined time interval after the pulse is given to the second signal, and the second correction signal is the first correction signal. A third pulse after the first pulse is applied to the first correction signal and before the second pulse is applied to the first correction signal, and a fourth pulse is applied to the first correction signal after the second pulse is applied. A digital pulse signal, further comprising a time interval (t2) from the application of the first pulse to the application of the third pulse and the application of the fourth pulse after the application of the second pulse. Until Are different in time interval (t3), and in the time-voltage conversion means, the first signal and the second signal
Signal, the first correction signal, and the second correction signal are input, and a period from when the pulse of the first signal is input to when the pulse of the second signal is input, 1
Voltage value from the input of the third pulse to the input of the third pulse, and the period from the input of the second pulse to the input of the fourth pulse at a constant ratio. Output an analog voltage signal, and the arithmetic means analyzes the input analog voltage signal, from the input of the pulse of the first signal to the input of the pulse of the second signal. Increase amount (V1) of the voltage value and the increase amount (V2) of the voltage value from the input of the first pulse to the input of the third pulse
And an increase amount (V3) of the voltage value from the input of the second pulse to the input of the fourth pulse, and detecting the increase of the voltage value of the first signal from the input of the pulse of the first signal. Two
Time interval (t1) until the pulse of the signal is input
T1 = (t3-t2) * (V1-V2) / (V3-V
2) The distance measuring device according to claim 1, wherein the distance to the target object is calculated by obtaining it from + t2.