JP3486223B2 - Distance measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the emission of pulsed light to a target.
And measure the time it takes for the reflected light to return.
And a distance measuring device that measures the distance to the target
Related. [0002] 2. Description of the Related Art Conventionally, technologies in such a field include:
Japanese Patent Laying-Open No. 4-1289 is known. This publication
The configuration of the conventional distance measuring device described in FIG.
Shown in the figure. As shown in FIG.
Emits laser diode 201 in response to a light emission signal from
And emit a laser beam toward the target. laser
The light is reflected by the target, and the photodiode of the receiving unit 220
221 is received. Light emission of laser diode 201
Light emission output from the transmission unit 200 according to the timing
The timing signal and the light receiving time of the photodiode 221
Reflected signal output from the receiving unit 220 according to the timing
Are given to the time measuring unit 230. Time measurement unit 230
Now, 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
It is counted by a counter 211 of 210. In the control unit 210
Is calculated based on the count value of the counter 211
Then, the distance to the target is detected. [0003] SUMMARY OF THE INVENTION However, the conventional
In the distance measuring device, the distance is determined by the clock cycle of the counter 211.
Because accuracy is determined, improvement in distance accuracy cannot be expected
There was a problem. [0004] The present invention solves such a problem and solves the problem.
An object of the present invention is to provide a highly accurate distance measuring device. [0005] [MEANS FOR SOLVING THE PROBLEMS]
The distance measuring device according to the present invention includes: (a) emitting pulse light;
(B) the pulsed light emitted from the light emitting element
An analog that partially receives light and has an amplitude corresponding to the received light intensity
A monitor light-receiving element for outputting a pulse voltage signal; and (c)
The other part of the pulsed light emitted from the light emitting element is
Receives light reflected by objects and has an amplitude corresponding to the received light intensity
Detector for outputting analog pulse voltage signal
And (d) input the signal output from the monitoring light receiving element
Output a digital pulse signal with reduced time jitter.
(E) detecting means for detecting light,
Input signal and reduce the time jitter.
Second discriminating means for outputting a pulse signal;
A first signal output from the first discriminating means and a second discriminating means;
The second signal output from the stage is input, and the signal of the first signal is input.
Pulse is input after the pulse is input.
Analog voltage whose voltage value increases at a fixed rate
Time-voltage conversion means for outputting a pressure signal;
The analog voltage signal output from the conversion means is input and the
The pulse of the second signal after the pulse of the first signal is input
To the target based on the amount of increase in the voltage value until the
Calculating means for calculating the distance at the first position, and the first discriminating means
And a second discriminating means for inputting signals to these discriminating means.
From the signal whose signal has been delayed for a predetermined time,
Subtract the attenuated signal and subtract the value
Digital pulse signal that gives a pulse when
And the first correction signal and the first correction signal.
Correction signal output for providing the correction signal of No. 2 to the time-voltage conversion means
Means, wherein the first correction signal has a pulse in the first signal.
Before or after the second signal is pulsed
And a first pulse and a second pulse at predetermined time intervals.
And a second correction signal.
After the first pulse is given to the first correction signal and
Give a third pulse before one second pulse is given
And after the second pulse is given to the first correction signal
A digital pulse signal for giving a fourth pulse;
The third pulse is given after the first pulse is given
Time interval (t2) until the second pulse is given
Time interval from when the fourth pulse is given (t)
3) is different, and in the time-voltage converting means, the first
Signal, the second signal, the first correction signal, and the second correction signal
And the second signal after the pulse of the first signal is input.
The first pulse until the signal pulse of
From input to the input of the third pulse
The fourth pulse during and between the input of the second pulse
The voltage value increases at a fixed rate during the period until
And outputs the analog voltage signal to the arithmetic means.
The analog voltage signal is analyzed and the pulse of the first signal is
From the input to the input of the second signal pulse
The voltage value increase (V1) and the first pulse are input
Of the voltage value until the third pulse is input from
(V2) and the fourth pulse after the input of the second pulse
The amount of increase (V3) in the voltage value until the power is input is detected
Then, after the pulse of the first signal is input, the second signal
The time interval (t1) until a pulse is input is expressed as t1 =
(T3-t2) × (V1-V2) / (V3-V2) + t
Calculate the distance to the target by obtaining from 2
Things. [0006] [0007] According to the distance measuring device of the present invention, from the light emitting element
A part of the emitted pulse light is received by the monitor light receiving element.
It is. Another part of the pulsed light is emitted toward the target
The light reflected by the target is received by the light receiving element for detection.
You. The monitor light receiving element controls the light intensity of the received pulse light.
An analog pulse voltage signal having a corresponding amplitude is generated.
Is supplied to the first discriminating means. First discrimination
Means to reduce the time jitter of the input signal
A pulse signal is generated and output. Specifically, input
Attenuates the amplitude of the input signal and the signal obtained by delaying the signal for a predetermined time
And a signal delayed by a predetermined time.
Subtract the signal whose width has been attenuated, and subtract
Digital pulse signal that gives a pulse when the value of
Generate and output a signal. Similarly, the detection light-receiving element
The analog pulse voltage signal is provided to the second discriminating means,
Digital pulse signal with reduced jitter
You. The first signal output from the first discriminating means
And the second signal output from the second discriminating means is a time voltage
Provided to the conversion means, and the pulse of the first signal is inputted.
Constant during the period until the pulse of the second signal is input from
The analog voltage signal whose voltage value increases by the ratio of
You. This analog voltage signal is given to the arithmetic means,
After the pulse of the second signal is input, the pulse of the second signal
Up to the target based on the amount of increase in the voltage value until input
Is calculated. According to the distance measuring device of the present invention,
A first correction signal output from the correction signal output means;
The second correction signal is a time signal together with the first and second signals.
Pressure conversion means. By inputting these correction signals
Therefore, the pulse of the first signal is input from the time-voltage conversion means.
Period from the input to the input of the second signal pulse
During the period, the third pulse is input after the first pulse is input
Until the second pulse is input
At a fixed rate during the period until the fourth pulse is input
An analog voltage signal whose voltage value increases is output.

           In the arithmetic means, a pulse of the first signal is inputted.
From the time when the second signal pulse is input
The amount of increase in the third pulse after the input of the first pulse
The amount of increase in the voltage value until the pulse is input and the second pulse
From the input of the pulse to the input of the fourth pulse.
The distance to the target is calculated while compensating for the increase in the pressure value
Is done. [0011] BRIEF DESCRIPTION OF THE DRAWINGS FIG.
It will be described with reference to FIG. FIG. 1 shows a distance measuring device according to the present embodiment.
FIG. 2 is a block diagram illustrating a configuration of a device 1. Based on the figure,
The example distance measuring device 1 is a pulse laser that emits laser light.
Laser 10 and a laser light emitting module
A monitoring sensor 20 for monitoring the imaging, and a laser beam
A detection sensor that receives light reflected from the target object
And 30. In addition, pulse laser 10
Pulse laser oscillation circuit 40 for providing a laser emission signal
And an amplifier 50 for amplifying the output of the monitor sensor 20
And the time jitter of the light emission pulse signal amplified by the amplifier 50.
CFD (Constant Fraction)
Discriminator) circuit 60. Further, the output of the detection sensor 30 is amplified.
Amplifier 70 and the detected pulse signal amplified by amplifier 70.
CFD circuit 80 for detecting time jitter of signal
And the output (start signal) of CFD circuit 60 and CF
Input the output (stop signal) of the D circuit 80
Output an analog voltage signal proportional to the pulse interval
TAC (Time-to-Amplitude Converter) circuit 90
Have. Furthermore, the output from the TAC circuit 90
A that converts an analog voltage signal into a digital voltage signal
The DC circuit 100 and the data output from the ADC circuit 100
Input a digital voltage signal and calculate the distance to the target
Control circuit 110 to generate a reference sequence inside the apparatus.
And an internal sequence generation circuit 120 for generating
You. A laser beam is focused on the front surface of the pulse laser 10.
The projection lens 11 for irradiating the target is used for detection.
The light reflected by the target is collected on the front surface of the sensor 30.
Light receiving lens 31 and band pass filter for removing disturbance light
32 are arranged respectively. FIG. 2 is a perspective view of the distance measuring device 1 of the present embodiment.
It has the appearance as shown in the figure. From this figure, this device
The case 1 is housed in a rectangular parallelepiped case 150.
An emission window 151 for emitting laser light is provided on the front surface of
An entrance window 152 through which the laser light reflected by the target is incident is provided.
Have been. Inside the case 150 is the front regions 150a, 15
0b and a rear region 150c. Soshi
In the front region 150a behind the exit window 151,
The laser 10, the projection lens 11, the monitor sensor 20, and the laser
Printed circuit board 16 incorporating a loose laser oscillation circuit 40
0 is disposed at a predetermined position. In addition, the entrance window 15
2 in the front area 150b behind, the light detection sensor 30
Light receiving lens 31, band pass filter 32, and amplifier 70
The printed board 161 with the built-in is arranged in a predetermined position
Have been. Further, the rear region 150c includes CFD times.
Pudding incorporating the roads 60 and 80, the TAC circuit 90, etc.
Printed circuit board incorporating the control board 110 and the control board 162
163 are arranged in two stages. Next, the operation of this embodiment will be described with reference to FIG.
This will be described with reference to the timing chart of FIG.
You. Pal output from internal sequence generation circuit 120
The laser emission signal 130 (FIG. 3A) is a pulsed laser.
The pulse laser 10 is input to the oscillation circuit 40 and emits light.
You. Most of the emitted laser light passes through the projection lens 11
The target is irradiated toward the target. In addition, the emitted laser light
Part of the light is received by the monitor sensor 20 and depends on the received light intensity.
An analog pulse voltage signal having the same amplitude is output.
After the analog pulse voltage signal is amplified by the amplifier 50
The CFD is used as the light emission pulse signal 131 (FIG. 3B).
The circuit 60 is provided. The laser beam reflected by the target is received by the light receiving lens 3
1 for detection through a bandpass filter 32
The light is received by the sensor 30. The bandpass filter 32 is
Function to pass only light of the same wavelength as the laser light
Therefore, most of the disturbance light is
It is not removed and given to the detection sensor 30.
The detection sensor 30 has an amplitude corresponding to the received light intensity.
An analog pulse voltage signal is output. Analog pulse
After the voltage signal is amplified by the amplifier 70, the detection pulse signal
No. 132 (FIG. 3C) to the CFD circuit 80.
It is. The CFD circuits 60 and 80 include pulse lasers.
O in accordance with the pulse rising timing of the light emission signal 130
During the period corresponding to the N state and the maximum distance measured by the device
The gate signal 133 (FIG. 3D) holding this state is
Given. When the gate signal 133 is turned on
Therefore, each of the CFD circuits 60 and 80 becomes operable.
The detection of the reflected light is performed only during the period. The distance to the target is the maximum distance measured by the device.
In the following cases, each CFD circuit 60, 80
Start signal 135 (FIG. 3E) and stop signal 136
(FIG. 3 (f)) is output and given to the TAC circuit 90.
You. These signals 135 and 136 are light emission pulse signals 1
31 and detection pulse signal 132
Signal. The TAC circuit 90 has an internal sequence.
The correction start signal 137 (FIG.
(G)) and the correction stop signal 138 (FIG. 3 (h)).
Given. The correction start signal 137 is a stop signal.
After a pulse is given to the signal 136, at a predetermined time interval,
A digital pulse for providing a first pulse and a second pulse;
Luz signal. The correction stop signal 138 is
After the first pulse is given to the positive start signal 137
And a third pulse is given before the second pulse is given.
And a second pulse as the correction start signal 137.
Digital pulse giving the fourth pulse after
Signal. Time interval between first pulse and third pulse
(T_ST1), The time interval between the second pulse and the fourth pulse
(T_ST2) Are known and the time interval (t_ST1)
More time interval (t_ST2) Is adjusted to be wider
ing. In the TAC circuit 90, the start signal 135
Pulse of the stop signal 136 after the pulse of
Until the first pulse is input
And the period until the third pulse is input, and the second
From the input of the pulse until the input of the fourth pulse
Voltage signal whose voltage value increases at a fixed rate during
No. 139 (FIG. 3 (i)) is generated. This analog phone
The pressure signal 139 is input to the ADC circuit 100,
AD timing signal supplied from the cans generation circuit 120
A / D conversion is performed in synchronization with signal 140 (FIG. 3 (j)).
You. This A / D conversion allows a high-resolution digital
A pressure signal 141 (FIG. 3 (k)) is generated and the control circuit 11
0 is given. In the control circuit 110, the input digital
The voltage signal 141 is analyzed, and the
Pulse is input after the stop signal 136 is input.
The amount of increase in the voltage value until_D) And the first pal
From the input of the pulse to the input of the third pulse.
Increase in pressure value (V_ST1) And the second pulse is input
Of the voltage value from the time till when the fourth pulse is input
(V_ST2) Is detected. Then, the following formula (formula
The calculation according to 1) is performed, and the pulse of the start signal 135 is output.
Is input, and then a pulse of the stop signal 136 is input.
Time interval (t_D) Is required. [0021]   t_D= (T_ST2-T_ST1) × (V_D-V_ST1) / (V_ST2-V_ST1) + T
_ST1                                                           ... (Equation 1) The time interval thus obtained (t_D)On the basis of the
By calculating the distance to the target, the TAC circuit 9
0 low-frequency range baseline due to external temperature fluctuations
Distance fluctuations and ramp waveform gradient fluctuations for stable distance measurement
Measurement can be performed in a short time. If the distance to the target is the maximum measured by the device
If the distance is longer than the distance, an undetected signal from the CFD circuit 80 is output.
134 is given to the control circuit 110 and the target
The distance measurement to the object ends. In the control circuit 110, in addition to the above calculations,
Error signal 14 output from loose laser oscillation circuit 40
2 and the undetected signal 134 output from the CFD circuit 80.
The input is used to manage the operation state of the apparatus. Further
In addition, the control circuit 110 controls the interface with external devices.
I am going. The distance measuring apparatus 1 according to the present embodiment
The distance of the laser light emitted from the pulse laser 10
Until it is reflected by the target and returns to the detection sensor 30
This is a device that obtains by measuring the time interval.
CFD times for higher accuracy and shorter measurement time
The circuits 60 and 80 and the TAC circuit 90 are combined.
It is characterized by the fact that In other words, the same distance measurement
The output fluctuation of the pulse laser 10 and the reflectivity of the target object.
Analog pulse voltage signal due to light intensity fluctuation due to difference
(Outputs from the monitor sensor 20 and the detection sensor 30)
Force signal), these analog pulses
By changing the voltage signal through the CFD circuits 60 and 80,
Digital that is not affected by motion (no time jitter)
A (trigger) signal is generated. This digital signal is T
Since it is provided to the AC circuit 90, the distance to the target is increased.
It can be measured with high accuracy. Further, the distance measuring device 1 of the present embodiment
Measurement signal (start signal 135, stop signal 13
6) and a correction signal having a known pulse interval (correction star).
TAC signal and the correction stop signal 138)
To the circuit 90 and output from the TAC circuit 90.
The distance to the target based on the three types of voltage increase
There is a characteristic in that it is calculated. Thus multiple voltage increases
By calculating based on the amount, T
Stable distance measurement by suppressing low frequency fluctuation of AC circuit 90
Can be performed. Here, the characteristics of the preceding stage (CFD circuit)
By combining the TAC circuit 90 with the 60, 80
In order to achieve high measurement accuracy), TA
A correction signal (correction start signal 137,
A correction stop signal 138) must be given to perform the correction processing.
The point is not necessarily. In other words, an environment where temperature fluctuations are unlikely
When the distance measuring device 1 is used, the TAC circuit 90
It is not necessary to consider the correction of low-frequency fluctuations in
In such a case, there is no need to supply a correction signal to the TAC circuit 90.
Good. When no correction signal is given, the control circuit 110
Is the amount of increase in the voltage value of the analog voltage signal 139 (V_D)of
Is detected, and this increase (V_D)
Is calculated. Next, the CFD times used in the present embodiment will be described.
The road will be described. A CFD circuit is an analog input signal
Signal rise time (leading edge) time is constant and amplitude
A constant timing pulse (di-
Digital). 4 (a)
Road blocks are shown in FIGS. 4 (b) to 4 (f).
Shown. The operation of the CFD circuit will be described with reference to these figures.
You. Constant rise time (t_r) And the amplitude voltage (V)
Is different from the analog input signal A (see FIG. 4B).
When input to the D circuit, the input signal A
This is provided to delay circuit 171. Input in the attenuation circuit 170
The signal B in which the amplitude of the signal A is attenuated to 1 / n (see FIG. 4C)
Is generated. In the delay circuit 171, the input signal A
To t_dSignal C (see FIG. 4 (d)) delayed by
Is done. These two signals B and C are applied to the differential amplifier 172
And a signal D obtained by subtracting the signal B from the signal C (see FIG.
4 (e)) is generated. The signal D is output from the ADC circuit 17
3 and a point a crossing zero (ground potential) is detected.
Will be issued. Then, it is turned on at the detection timing of the point a.
The rising digital pulse signal E (see FIG. 4 (f))
Is output. Here, the time at which the point a occurs is t_d+ T_r
/ N can be expressed as a digital pulse signal.
E is a signal irrelevant to the amplitude voltage (V) of the analog input signal A.
It turns out that it is a number. This means that the analog input signal A
Rise time (t_rEven if not fluctuating, even if the amplitude
Even if the voltage (V) fluctuates, the digital pulse signal E
This means that there is no fluctuation between signals. The distance measuring device 1 of the present embodiment shown in FIG.
Is caused by fluctuations in the output of the pulse laser 10 and the reflectivity of the target.
The effect of light intensity fluctuation due to
A certain light emission pulse signal 131 and a detection pulse signal 132
Appears in the waveform. The effect of this variation is that amplifiers 50 and 70
By providing CFD circuits 60 and 80 at the subsequent stage.
A digital pulse signal (star
Signal 135 and stop signal 136) can be obtained.
You. Although the technical field is different from that of this embodiment, CF
Conventional circuit technology combining D circuit and TAC circuit
Is disclosed in the document of JP-A-61-266942.
Have been. Next, a distance measurement according to another embodiment of the present invention will be described.
For the device 2, the block diagram of FIG.
This will be described with reference to the waveform diagram. The distance measuring device of this embodiment
The device 2 is used to change the output of the pulsed laser light or
From the signal containing the light intensity fluctuation due to the difference in the reflectance of the target,
AGC circuits 180 and 181 for generating a constant pulse waveform,
The rising edge of the pulse waveform signal is detected at a constant voltage level.
LED that generates timing pulse with little time jitter
By combining the circuits 182 and 183,
It is characterized in that accurate distance measurement can be performed. Here, the distance measuring device 2 shown in FIG.
The difference from the distance measuring device 1 is that the amplifiers 50 and 70
AGC circuits 180 and 181 and a CFD circuit 6
LED circuits 182 and 183 are provided instead of 0 and 80
It is a point. For this reason, the distance measuring device 2 is as follows.
Operate. First, the internal sequence generating circuit 120
The output pulse laser emission signal 130 (FIG. 6A)
Is input to the pulse laser oscillation circuit 40, and the pulse laser
10 is caused to emit light. Most of the emitted laser light is
The target 11 is irradiated through the lens 11. Also luminous
A part of the laser light is received by the monitor sensor 20,
Analog pulse voltage signal with amplitude corresponding to received light intensity
(FIG. 6B) is output. Analog pulse voltage signal
Is controlled by the AGC circuit 180 so that the voltage amplitude becomes constant
Then, as the light emission pulse signal 131 (FIG. 6C), LE
D circuit 182 is provided. In the LED circuit 182,
Detect rising edge of optical pulse signal 131 at constant voltage level
Digital pulse start signal with reduced time fluctuation
135 (FIG. 6D) is output. The laser light reflected by the target is received by the light receiving lens 3
1 for detection through a bandpass filter 32
The light is received by the sensor 30. Receives light from detection sensor 30
Analog pulse voltage signal with amplitude corresponding to the intensity (Figure
6 (e)) is output. Analog pulse voltage signal is A
Control is performed by the GC circuit 181 so that the voltage amplitude becomes constant.
The detection pulse signal 132 (FIG. 6 (f))
The circuit 183 is provided. The LED circuit 183 detects
The rising of the pulse signal 132 is detected at a constant voltage level,
Digital pulse stop signal 13 with reduced time fluctuation
6 (FIG. 6 (g)). Start signal 135 and stop signal 1
36 is input to the TAC circuit 90 and the start signal 135
The voltage increases in proportion to time from the leading edge of
And the leading edge of the stop signal 136
Analog voltage signal 139 for stopping voltage increase
(FIG. 6 (h)) is generated. Generated analog voltage
The signal 139 is input to the ADC circuit 100, and the internal sequence
AD timing signal given from the sense generation circuit 120
A / D conversion is performed in synchronization with 140 (FIG. 6 (i)).
You. This A / D conversion allows a high-resolution digital
A pressure signal 141 (FIG. 6 (j)) is generated and the control circuit 11
0 is given. In the control circuit 110, the inputted digital
The digital voltage signal 141 is analyzed, and the distance to the target is
Is calculated. Thus, the time difference proportional to the distance (l)
By measuring (Δt) as an analog voltage (V),
This enables highly accurate distance measurement. AGC circuit
181 and the LED circuit 183 for detection
Weak light detection by the sensor 30 has become possible. For this reason,
Easy even when the target is far away and the reflected light is very weak
Distance measurement. The present invention is not limited to the above embodiment.
Various modifications are possible. For example, in this embodiment,
Is the correction star after the pulse is given to the stop signal.
Pulse (first pulse ~)
4th pulse), but the start signal
Before the pulse is given, the correction start signal and the correction
A pulse may be given to the tap signal. In the distance measuring device 2, the TAC circuit 9
At 0, only the start signal 135 and the stop signal 136
Input, but the correction start signal 137 and the correction
When the stop signal 138 is input to the TAC circuit 90,
Corrects output voltage fluctuation of TAC circuit 90 due to temperature fluctuation
May be. [0039] As described in detail above, the distance according to the present invention is
If it is a distance measurement device, it is not affected by output fluctuation of the input signal.
Digital pulse signal is separated from the first discriminating means and the second discriminating means.
The digital pulse signal generated by
Input to the conversion means. For this reason, the output fluctuation of the light emitting element
Monitor by output fluctuation due to difference in reflectance of target and target
Of the signal output from the photo detector for detection and the photo detector for detection fluctuate
However, the voltage signal generated by the time-voltage conversion means
It is not affected by output fluctuations. Therefore, the calculation means
Now, based on the voltage signal generated by the time-voltage converter
The distance to the target with high accuracy.
You. Further, according to the present invention, reception is performed after the pulse light is emitted.
Analog voltage signal proportional to the time until light is emitted
Generated by the voltage conversion means, the distance from this analog voltage signal
Is calculated, the time is counted by a counter, and the distance is calculated.
Obtain higher distance accuracy than conventional technology that calculates
Can be.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of a distance measuring device according to the present embodiment. FIG. 2 is a perspective view showing an appearance of the distance measuring device according to the embodiment. FIG. 3 is a timing waveform chart of the distance measuring device according to the embodiment. FIG. 4 is an equivalent circuit block diagram and a timing waveform diagram of the CFD circuit. FIG. 5 is a block diagram illustrating a configuration of a distance measurement device according to another embodiment. FIG. 6 is a timing waveform chart of the distance measuring device according to another embodiment. FIG. 7 is a block diagram showing a configuration of a conventional distance measuring device. [Description of Signs] 1, 2 ... Distance measuring device, 10 ... Pulse laser, 11 ... Light emitting lens, 20 ... Monitoring sensor, 30 ... Detecting 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: Start signal for correction,
138: Stop signal for correction, 139: Analog voltage signal, 140: AD timing signal, 141: Digital voltage signal, 142: Error signal, 150: Case, 15
DESCRIPTION OF SYMBOLS 1 ... Outgoing window, 152 ... Ingress 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.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-106587 (JP, A) JP-A-6-118173 (JP, A) JP-A-58-37576 (JP, A) JP-A-3- 81687 (JP, A) JP-A-61-266942 (JP, A) JP-A-59-60271 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01S 7/48-7 / 51 G01S 17/00-17/95

Claims (1)

(57) [Claim 1] A light emitting element for emitting pulsed light, and an analog pulse voltage signal which receives a part of the pulsed light emitted from the light emitting element and has an amplitude corresponding to the received light intensity A light receiving element for monitoring, which outputs a pulsed light emitted from the light emitting element, receives light reflected by a predetermined target, and outputs an analog pulse voltage signal having an amplitude corresponding to the received light intensity. A detection light receiving element, first discriminating means for receiving a signal output from the monitoring light receiving element and outputting a digital pulse signal with reduced time jitter, and a signal output from the detection light receiving element. A second discriminating means for inputting and outputting a digital pulse signal with reduced time jitter; a first signal outputted from the first discriminating means and a second signal outputted from the second discriminating means. A time-to-voltage converter that inputs a signal and outputs an analog voltage signal whose voltage value increases at a fixed rate during a period from when the pulse of the first signal is input to when the pulse of the second signal is input. Means for inputting an analog voltage signal output from the time-to-voltage conversion means, and increasing the voltage value from the input of the pulse of the first signal to the input of the pulse of the second signal. Computing means for calculating a distance to the target based on the input signal, wherein the first discriminating means and the second discriminating means determine whether the input signal to the discriminating means is delayed by a predetermined time from the input signal. Subtract the signal with the signal amplitude attenuated,
And a correction signal output means for outputting a digital pulse signal for giving a pulse when the subtracted value becomes a predetermined value, and for giving a first correction signal and a second correction signal to the time-voltage conversion means. The first correction signal includes a first pulse and a second pulse at predetermined time intervals before a pulse is applied to the first signal or after a pulse is applied to the second signal. A digital pulse signal to be provided, wherein the second correction signal provides a third pulse after the first pulse is supplied to the first correction signal and before the second pulse is supplied. A digital pulse signal that provides a fourth pulse after a second pulse is supplied to the first correction signal, and further receives the third pulse after the first pulse is supplied. And the time interval (t3) from when the second pulse is applied to when the fourth pulse is applied is different. Signal and said second
, The first correction signal, and the second correction signal are input, and during the period from when the pulse of the first signal is input to when the pulse of the second signal is input, 1
At a fixed rate during a period from the input of the first pulse to the input of the third pulse, and a period between the input of the second pulse and the input of the fourth pulse. Is output, and the arithmetic means analyzes the input analog voltage signal and outputs the second signal after the pulse of the first signal is input.
(V) until the signal pulse is input
1) and the amount of increase (V2) in the voltage value from the input of the first pulse to the input of the third pulse;
Detecting the amount of increase (V3) in the voltage value from 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 represented by: t1 = (t3-t2) × (V1-V2) / (V3-V
2) A distance measuring device for calculating the distance to the target by obtaining the distance from + t2.