JPH0886870A - Laser rangefinder - Google Patents

Abstract

PURPOSE: To obtain a laser rangefinder which has a small rangefinding error by obtaining a time difference and correcting a distance. CONSTITUTION: A means 9 for obtaining Δt1 measures the time Δt1 from a start pulse 6 generating time to the time for generating a clock 8 initially by a clock generator 4 after the pulse 6 is started. A means 10 for obtaining t2 measures the time Δt2 from a stop pulse 7 generating time to the time for generating the clock 8 initially by the generator 4 after the pulse 7 is generated. A correcting means 11 corrects the distance to a target obtained by a calculator 5 by using the obtained Δt1 and the Δt2 .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser range finder for obtaining a distance from a target to a time when a laser pulse transmitted to the target returns from the target.

[0002]

2. Description of the Related Art A conventional device of this type is Clifton.
S. Fox edition, “The Infrared & El
electro-Optical Systems Han
dbbook] (1993) Volume6, Activ
e Electro-Optical Systems
Page 81 of FIG. 10 and has the block configuration shown in FIG. In the figure, 1 is a laser transmitter, 2 is a laser receiver, 3 is a counter, 4 is a clock generator, 5
Is a calculator, 6 is a start pulse, 7 is a stop pulse,
Reference numeral 8 is a clock generated by the clock generator 4.

Next, the operation will be described. The laser transmitter 1 is a laser oscillator that generates a laser pulse, a transmission optical system that sends a laser pulse (not shown) to a target (not shown), and at the same time when the laser pulse is generated, a part of the laser pulse is received and photoelectrically converted. It consists of a photodetector that generates a start pulse 6 which is a digital signal. The laser pulse is reflected or diffused by the target, and a part of the laser pulse returns to the laser range finder and is detected by the laser receiver 2. The laser receiver 2 comprises a receiving optical system that collects the laser pulse returned from the target, and a receiving circuit that photoelectrically converts the laser pulse and amplifies it to generate a stop pulse 7 that is a digital signal. The clock generator 4 sends a clock 8 having a period T to the counter 3. When the counter 3 receives the start pulse 6, it starts counting the clock 8.
When the stop pulse 7 is received, counting is stopped. Calculator 5
Receives the count value N of the clock 8 from the counter 3 and calculates the distance R to the target by the equation (1) using the speed of light C.

[0004]

[Equation 1]

[0005]

The conventional laser distance measuring apparatus obtains the distance to the target by the equation (1) constructed as described above. By the way, an error occurs in the distance obtained by the equation (1) due to the following factors. (A) An error caused by a quantization error in the generation time of the start pulse 6. (B) An error caused by a quantization error in the generation time of the stop pulse 7. (C) An error caused by the manufacturing error of the period T of the clock 8 of the clock generator 4, that is, the frequency f.

The above factor (a) will be described in detail.
For example, when the counter 3 rises at the clock 8 and the clock 8
11 is counted, the counting is started from the first rising edge of the clock 8 after the generation of the start pulse 6 as shown in the time chart of FIG. The numbers shown above the waveform of the clock 8 in the figure are the count values of the counter 3. When calculating the distance to the target by the equation (1), the calculator 5 converts the count value 1 of the counter 3 into the time T. Therefore, as shown in FIG. 11, it is considered that T is the time difference Δt ₁ from the time when the start pulse 6 is generated to the time when the clock 8 is first counted. For this reason, T-Δt ₁ hour is increased. Therefore, there is a problem that the distance calculated by the equation (1) becomes longer than the actual distance by the distance given by the equation (2).

[0007]

[Equation 2]

The above factor (b) will be described in detail.
FIG. 12 is a time chart similar to FIG. 11, showing the timing of the clock 8 and the stop pulse 7. When the counter 3 receives the stop pulse 7, it stops counting the clock 8. That is, counting is performed up to the rising edge of the Nth clock 8 before the stop pulse 7 is generated in the figure. In this case, the stop pulse 7 is generated T-Δt ₂ time after the counter 3 counts the Nth clock 8. However, in the formula (1), the distance to the target is obtained by the time when the Nth clock 8 is counted, so the formula (3)
There was a problem that it was shorter than the actual distance given by.

[0009]

(Equation 3)

The above factor (c) will be described in detail.
The arithmetic unit 5 stores the speed of light C and the period T of the clock 8 in advance in order to obtain the distance to the target by the equation (1). A design value is used for the cycle T, in other words, the frequency f, but a manufacturing error occurs in an actual product. A crystal oscillator is normally used as the clock generator 4, but the frequency f of the crystal oscillator has a slight manufacturing error Δf.
Exists. However, since the frequency error Δf is not taken into consideration when the distance is calculated by the conventional expression (1), the distance measurement error increases by the expression (4) in proportion to the distance R to the target, and the distance longer than the actual distance is calculated. There was a problem that they would ask.

[0011]

[Equation 4]

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a laser distance measuring device having a very small distance measuring error.

[0013]

In order to achieve the above object, the laser distance measuring apparatus according to the first embodiment of the present invention includes a means for obtaining a time difference Δt ₁ , a means for obtaining a time difference Δt ₂ , and an arithmetic unit. And a means for correcting the calculated distance.

Further, the laser range finder of the second embodiment according to the present invention comprises a second clock generator and a second counter as means for obtaining Δt ₁ of the laser range finder of the _first embodiment. Δt ₁ is obtained using the count value of the second counter and the clock cycle of the second clock generator.

Further, the laser distance measuring apparatus according to the third embodiment of the present invention is a means for obtaining Δt ₁ of the laser distance measuring apparatus according to the _first embodiment, and means for branching into a plurality of branch lines and each of the plurality of branch lines. The system is provided with delay lines having different delay times and means for taking a logical product in each of the plurality of branch lines, and the delay time corresponding to Δt ₁ is selected from the result of the logical product.

Further, the laser range finder of the fourth embodiment according to the present invention has a gate circuit, a means for generating a pulse train, and a third counter as means for obtaining Δt ₁ of the laser range finder of the first embodiment. And Δt ₁ is obtained using the count value of the third counter and the cycle of the pulse train.

Further, the laser distance measuring apparatus of the fifth embodiment according to the present invention comprises a third clock generator and a fourth counter as means for obtaining Δt ₂ of the laser distance measuring apparatus of the first embodiment. Δt ₂ is obtained using the count value of the fourth counter and the clock cycle of the third clock generator.

Further, the laser range finder of the sixth embodiment according to the present invention has means for branching into a plurality of branch lines and each of the plurality of branch lines as means for obtaining Δt ₂ of the laser range finder of the first embodiment. The system is provided with delay lines having different delay times and means for obtaining a logical product in each of the plurality of branch lines, and the time delay amount corresponding to Δt ₂ is selected from the result of the logical product.

Further, the laser range finder of the seventh embodiment according to the present invention has a gate circuit, a means for generating a second pulse train, and a means for obtaining Δt ₂ of the laser range finder of the first embodiment. 5 counter, and Δt ₂ is obtained using the count value of the fifth counter and the cycle of the pulse train.

Further, the laser distance measuring apparatus according to the eighth embodiment of the present invention comprises means for correcting the distance calculated by the arithmetic unit using the design value f of the clock frequency of the clock generator and its manufacturing error Δf. It was done like this.

[0021]

Means for determining a Delta] t ₁ of the laser distance measuring apparatus of the first embodiment [action] is constructed as described above, from the time the start pulse occurs the counter is time to count the first clock after the start pulse generator The means for obtaining the difference and obtaining Δt ₂ obtains the difference between the time when the stop pulse is generated and the time when the clock first arrives at the counter after the stop pulse is generated, and the means for correcting is the obtained Δt ₁ And Δt ₂ are used to correct the distance calculated by the arithmetic unit.

Further, the second clock generator of the laser distance measuring apparatus of the second embodiment having the above-mentioned configuration uses the second clock having the cycle T ₂ shorter than the cycle T of the clock generated by the clock generator. The second counter receives the start pulse, starts counting the second clock, and stops counting the second clock by the clock from the clock generator which comes first after the start pulse is generated.

Further, the branching means of the laser distance measuring apparatus of the third embodiment configured as described above branches the start pulse into a plurality of branch lines, and the delay line delays the start pulse with different delay times to obtain a logic signal. The means for taking the product takes the logical product of the start pulse and the clock from the clock generator.

Further, a fourth embodiment constructed as described above.
The gate circuit of the laser distance measuring device opens the gate by receiving the start pulse, allows the input signal to pass through, and closes the gate by the clock from the clock generator that first arrives after the start pulse, and shuts off the input signal. To do. The means for generating a pulse train delays the start pulse one after another to generate a pulse train, and the third counter counts the number of pulses passing through the gate circuit in the pulse train.

The third clock generator of the laser range finder of the fifth embodiment configured as described above uses the third clock having a cycle T ₄ shorter than the cycle T of the clock generated by the clock generator. The fourth counter receives the start pulse, starts counting the third clock, and stops counting the third clock by the clock from the clock generator which comes first after the start pulse is generated.

Further, Example 6 configured as described above
In the laser range finder, the branching means branches the stop pulse into a plurality of branch lines, the delay line delays the stop pulse with different delay times, and the means for logical product is the stop pulse and the clock from the clock generator. AND with.

Further, Example 7 configured as described above
The gate circuit of the laser distance measuring device opens the gate by receiving the stop pulse, allows the input signal to pass, and closes the gate signal by the clock from the clock generator that first arrives after the stop pulse is generated. Cut off. The means for generating the second pulse train delays the stop pulse one after another to generate a pulse train, and the fifth counter counts the number of pulses passing through the gate circuit in the pulse train.

Further, an eighth embodiment constructed as described above.
The correction means of the laser distance measuring device of (1) adds the correction by subtracting (Δf / f) R from the distance R obtained by the arithmetic unit.

[0029]

【Example】

Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of the present invention. In the figure, 1 is a laser transmitter, 2 is a laser receiver, 3 is a counter, 4 is a clock generator, 5 is a calculator,
6 is a start pulse, 7 is a stop pulse, 8 is a clock, 9 is a means for obtaining Δt ₁ , 10 is a means for obtaining Δt ₂ , and 11 is a correcting means.

Next, the operation will be described. The calculation of the distance R to the target by the equation (1) by the calculator 5 is similar to the conventional example. Since the means 9 for obtaining Δt ₁ , the means 10 for obtaining Δt ₂ and the correcting means 11 are different from the conventional example, these will be described. The means 9 for obtaining Δt ₁ obtains the time difference Δt ₁ from the generation time of the start pulse 6 until the counter 3 first counts the clock 8 after the generation of the start pulse 6. The means 10 for obtaining Δt ₂ obtains the time difference Δt ₂ from the generation time of the stop pulse 7 until the clock 8 first reaches the counter 3 after the stop pulse 7 is generated. The correcting means 11 corrects the distance R calculated by the calculator 5 using the calculated Δt ₁ and Δt ₂ and sets the distance calculated by the equation (5) as the distance to the true target. From the expression (5), there is an effect that the error factors (a) and (b), which are problems in the conventional example, can be reduced.

[0031]

(Equation 5)

Example 2. The laser distance measuring apparatus according to the second embodiment of the present invention comprises a means 9 for obtaining Δt ₁ in the first embodiment as shown in FIG. In the figure, 6 is a start pulse,
Reference numeral 8 is a clock from the clock generator 4, 12 is a second counter, 13 is a second clock generator, and 14 is a second arithmetic unit.

Next, the operation will be described. In FIG. 2, the second clock generator 13 generates a second clock having a cycle T ₂ shorter than the cycle T of the clock generated by the clock generator 4, and the second counter 12 outputs the start pulse 6
To start counting the second clock, and stop counting the second clock by the clock 8 from the clock generator 4 which comes first after the start pulse 6 is generated. The second computing unit 14 uses the second counter 1
Using the count value N _{2 of 2} and the cycle T ₂ , Δt ₁ is calculated by the equation (6).

[0034]

(Equation 6)

The operation of correcting the distance obtained by the calculator 5 by the correcting means 11 using Δt ₁ obtained by the equation (6) is the same as in the first embodiment. In the present invention, in order to stop the counting of the second counter 12, it is necessary to select the clock 8 that comes first after the generation of the start pulse 6 and input it to the second counter 12. The clock 8 may be selected by providing a circuit that opens the gate for T time corresponding to the cycle of the clock 8 when the start pulse 6 is input, and allows the clock 8 to pass therethrough.

Example 3. The laser distance measuring apparatus according to the third embodiment of the present invention comprises a means 9 for obtaining Δt ₁ in the first embodiment, which is shown in FIG. In the figure, 6 is a start pulse,
8 is a clock, 15 is a branch circuit, 16 is a first delay line,
17 is a second delay line, 18 is an Mth delay line, 19 is an AN
The D circuit, 20 is a delay time selecting means.

Next, the operation will be described. In FIG. 3, the branch circuit 15 branches the start pulse 6 into a plurality of M branch lines, and the first delay line 16, the second delay line 17, and the Mth delay line 18 are installed in the respective branch lines and have different delays. Have time However, in the figure, description of the third to M-1th branch lines is omitted. This invention is effective when M is 2 or more. The AND circuit 19 takes the logical product of the start pulse 6 passing through the delay line and the clock 8 from the clock generator 4 in each branch line. Here, the first delay line 1
6, the delay time of the second delay line 17 and the delay time of the Mth delay line 18 are set between 0 and T. For example, the first delay line 1
Assuming that the delay time increases from the 6th to the Mth delay line 18 at a constant time interval T / M, the timings of the start pulse 6 and the clock 8 input to the means 19 for ANDing each branch line are as shown in FIG. It becomes 4. The numbers above the clock 8 are the count values of the counter 3 as in FIG. In FIG. 4, the start pulse 6 existing in the intervals A and C where the clock 8 is at the high level is the AND circuit 1
Pass 9 On the other hand, the start pulse 6 existing in the period B in which the clock 8 is at the low level does not pass through the AND circuit 19. The delay time selection means 20 stores the presence / absence of the start pulse 6 from each branch line, checks the presence / absence of the start pulse 6 of each branch line in ascending order of delay time, and selects the delay time at which the start pulse 6 changes from none to yes. . That is, FIG.
In, the delay time of the delay line of the branch line in which the start pulse 6 first exists in the period C is selected, and this is designated as Δt ₁ . The operation of correcting the distance obtained by the calculator 5 by the correction means 11 using this Δt ₁ is the same as that in the first embodiment.

Example 4. The laser distance measuring apparatus according to the fourth embodiment of the present invention comprises a means 9 for obtaining Δt ₁ in the first embodiment as shown in FIG. In the figure, 6 is a start pulse,
Reference numeral 8 is a clock, 21 is a pulse train generator, 22 is a gate circuit, 23 is a third counter, and 24 is a third arithmetic unit.

Next, the operation will be described. In FIG. 5, the pulse train generator 21 delays the start pulse 6 one after another and the cycle T shorter than the cycle T _{3 of the} clock 8 and the cycle T ₃ shorter than the cycle T _3.
The gate circuit 22 opens the gate by receiving the start pulse 6 to pass the pulse signal from the pulse train generator 21 which is input, and the clock generator 4 which arrives first after the start pulse 6 is generated. The gate 8 is closed by the clock 8 to shut off the input pulse signal. The third counter 23 counts the number of pulses of the pulse signal passing through the gate circuit 22.
The third calculator 24 counts the count value N of the third counter 23.
Δt _{1 is obtained} by the equation (7) using ₃ and the cycle T ₃ .
The operation of correcting the distance obtained by the calculator 5 by the correction means 11 using this Δt ₁ is the same as that in the first embodiment.

[0040]

(Equation 7)

The pulse train generator 21 is constructed as shown in FIG. 6 or 7. In FIG. 6, a delay loop having a delay time T ₃ is formed to delay the start pulse 6 one after another to form a pulse train. In the figure, 25 is an OR circuit that takes the logical sum of inputs, and 26 is a delay circuit having a delay time T ₃ .
The OR circuit 25 and the delay circuit 26 form a delay loop and
When the start pulse 6 is input to the R circuit 25, the output is re-input to the OR circuit 25 via the delay circuit 26. As a result, a pulse train of period T ₃ is generated with the configuration of FIG.
In FIG. 7, the start pulse 6 is delayed one after another using a delay line to form a pulse train. In the figure 15, 16,
Reference numerals 17 and 18 denote a branch circuit, a first delay line, a second delay line and an Mth delay line corresponding to FIG. 3, and 27 denotes a synthesizing circuit. The start pulse 6 is branched into M branch lines by the branch circuit 15, and the L-th delay line delays the start pulse 6 by (L-1) T ₃ time. However, L = 1
2, ..., M. The synthesizing circuit 27 synthesizes the start pulse 6 from each branch line to generate a pulse train composed of M pulses having a period T ₃ . Here, M and T ₃ are set so that the time M · T ₃ becomes equal to or longer than the cycle T of the clock 8.

Example 5. The laser distance measuring apparatus according to the fifth embodiment of the present invention comprises a means 10 for determining Δt ₁ in the first embodiment, which is shown in FIG. This configuration is one in which the start pulse 6 in the second embodiment is replaced with the stop pulse 7 and is the same as the second embodiment in principle. In the figure, 7 is a stop pulse, 8 is a clock from the clock generator 3, and 28
Is a fourth counter, 29 is a third clock generator, and 30
Is a fourth arithmetic unit.

Next, the operation will be described. In FIG. 8, the third clock generator 29 generates a third clock having a cycle T ₄ shorter than the cycle T of the clock generated by the clock generator 4, and the fourth counter 28 outputs the stop pulse 7
Is received, the counting of the third clock is started, and the counting of the third clock is stopped by the clock 8 that first arrives after the generation of the stop pulse 7. The fourth calculator 30 obtains Δt ₂ by the equation (8) using the count value N ₄ of the fourth counter 28 and the cycle T ₄ .

[0044]

[Equation 8]

The operation of correcting the distance obtained by the calculator 5 by the correcting means 11 using Δt ₂ obtained by the equation (8) is the same as in the first embodiment. In the present invention, since the counting of the fourth counter 28 is stopped, it is necessary to select the clock 8 that comes first after the generation of the stop pulse 7 and input it to the fourth counter 28. As a method of selecting the clock 8, it is sufficient to provide a circuit that opens the gate for the time T corresponding to the cycle of the clock 8 when the stop pulse 7 is input, and allow the clock 8 to pass therethrough.

Example 6. The laser distance measuring apparatus according to the sixth embodiment of the present invention uses the same principle as that of the third embodiment as the means 10 for obtaining Δt ₂ of the first embodiment. In the configuration of FIG. 3, a start pulse 6 and a stop pulse 7 are used. Is replaced with. By replacing the start pulse 6 with the stop pulse 7 in the detailed description of the third embodiment, the same operation as in the third embodiment is performed. However, the delay time selecting means 20 of the present invention calculates Δt ₂ instead of Δt ₁ . The operation of correcting the distance calculated by the calculator 5 by the correcting means 11 using the calculated tΔ ₂ is the same as in the first embodiment.

Example 7. The laser distance measuring apparatus according to the seventh embodiment of the present invention comprises a means 10 for obtaining Δt ₂ of the first embodiment, which is shown in FIG. In the figure, 7 is a stop pulse,
8 is a clock, 22 is a gate circuit, 31 is a second pulse train generator, 32 is a fifth counter, and 33 is a fifth calculator.

Next, the operation will be described. In FIG. 9, the second pulse train generator 31 delays the stop pulse 7 one after another to generate a pulse train having a period T ₅ shorter than the period T of the clock 8, and the gate circuit 22 opens the gate by receiving the stop pulse 7. The input pulse signal from the second pulse train generator 31 is passed, and the gate is closed by the clock 8 that first arrives after the generation of the stop pulse 7, and the input pulse signal is blocked. The fifth counter 32 counts the number of pulses of the pulse signal passing through the gate circuit 22. The fifth computing unit 33 is the fifth
Δ with the count value N ₅ and the period T ₅ of the counter 32
t ₂ is calculated by the equation (9). The operation of correcting the distance obtained by the calculator 5 by the correction means 11 using this Δt ₂ is the same as that in the first embodiment.

[0049]

[Equation 9]

The second pulse train generator 31 can be realized in the same manner as in the fourth embodiment by replacing the start pulse 6 with the stop pulse 7 in the configuration shown in FIG. 6 or 7.

The laser range finder of Example 8 of the present invention comprises:
In the conventional example, the distance R to the target obtained by the arithmetic unit 5 is corrected using the design value f of the frequency of the clock 8 and its manufacturing error Δf, and the distance obtained by the equation (10) is taken as the true target distance. . From the expression (10), there is an effect that the error factor (c), which is a problem in the conventional example, can be reduced.

[0052]

[Equation 10]

[0053]

According to the invention according to the first embodiment as described above, according to the present invention, correcting the measurement distance by the correction means using the time Delta] t ₁ and Delta] t ₂ determined by means for determining the means and Delta] t ₂ Request Delta] t ₁ Therefore, there is an effect that it is possible to reduce the error in the measurement distance due to the quantization error in the start pulse generation time and the quantization error in the stop pulse generation time.

As described above, according to the present invention according to the second embodiment, as a means for obtaining Δt ₁ , a second clock generator and a second counter are provided, and the count value of the second counter is provided. Since Δt ₁ is calculated using the clock cycle of the second clock generator, there is an effect that the error of the measurement distance due to the quantization error of the start pulse generation time can be reduced.

As described above, according to the present invention according to the third embodiment, as a means for obtaining Δt ₁ , a means for branching a start pulse into a plurality of branch lines and a delay line provided for each of the plurality of branch lines are provided. , And a means for obtaining a logical product in each of the plurality of branch lines, and the time delay amount corresponding to Δt ₁ is selected from the result of the logical product, which is caused by the quantization error of the start pulse generation time. This has the effect of reducing the error in the measurement distance.

Further, as described above, according to the present invention according to the fourth embodiment, as means for obtaining Δt ₁ , a gate circuit, means for generating a pulse train, and a third counter are provided, and the third counter is provided. Since Δt ₁ is obtained using the count value of the counter and the cycle of the pulse train, there is an effect that the error of the measurement distance due to the quantization error of the start pulse generation time can be reduced.

Further, as described above, according to the present invention according to the fifth embodiment, the third clock generator and the fourth counter are provided as means for obtaining Δt ₂ , and the count value of the fourth counter is provided. Since Δt ₂ is calculated using the clock cycle of the third clock generator, there is an effect that the error of the measurement distance due to the quantization error of the stop pulse generation time can be reduced.

Further, as described above, according to the present invention according to the sixth embodiment, as means for obtaining Δt _{2, there} are provided means for branching a stop pulse into a plurality of branch lines and delay lines provided for each of the plurality of branch lines. , And a means for obtaining a logical product in each of the plurality of branch lines, and the time delay amount corresponding to the Δt ₂ is selected from the result of the logical product, which results from the quantization error in the stop pulse generation time. This has the effect of reducing the error in the measurement distance.

Further, as described above, according to the present invention according to the seventh embodiment, as means for obtaining Δt ₂ , a gate circuit, means for generating a pulse train, and a fifth counter are provided, and the fifth counter is provided. Since Δt ₂ is obtained by using the count value of the counter and the period of the pulse train, there is an effect that the error in the measurement distance due to the quantization error in the stop pulse generation time can be reduced.

Further, as described above, according to the present invention according to the eighth embodiment, the distance R to the target is corrected by using the design value of the clock frequency and the manufacturing error. There is an effect that the error of R caused by the above can be reduced.

[Brief description of drawings]

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

FIG. 2 is a Δt of a second embodiment of the laser distance measuring device according to the present invention.
FIG. 3 is a block configuration diagram showing a means for obtaining ₁ .

FIG. 3 shows Δt of a third embodiment of the laser distance measuring device of the present invention.
FIG. 3 is a block configuration diagram showing a means for obtaining ₁ .

[FIG. 4] Δt of Embodiment 3 of the laser distance measuring apparatus of the present invention
It is a figure which shows the time chart of the means to calculate ₁ .

FIG. 5: Δt of Embodiment 4 of the laser distance measuring apparatus of the present invention
FIG. 3 is a block configuration diagram showing a means for obtaining ₁ .

[FIG. 6] Δt of Embodiment 4 of the laser distance measuring apparatus of the present invention
It is an embodiment of a pulse train generator for obtaining ₁ .

[FIG. 7] Δt of Embodiment 4 of the laser distance measuring apparatus of the present invention
It is another embodiment of the pulse train generator of the means for obtaining ₁ .

FIG. 8: Δt of Embodiment 5 of the laser distance measuring device of the present invention
FIG. 3 is a block configuration diagram showing means for obtaining ₂ .

[FIG. 9] Δt of Embodiment 7 of the laser distance measuring apparatus of the present invention
FIG. 3 is a block configuration diagram showing means for obtaining ₂ .

FIG. 10 is a block diagram showing a conventional example of a laser distance measuring device.

FIG. 11 is a diagram illustrating a quantization error of a start pulse generation time.

FIG. 12 is a diagram illustrating a quantization error of a stop pulse generation time.

[Explanation of symbols]

1 laser transmitter, 2 laser receiver, 3 counter,
4 clock generator, 5 arithmetic unit, 6 start pulse, 7 stop pulse, 8 clock, 9 Δt ₁ obtaining means, 10 Δt ₂ obtaining means, 11 correction means, 12 second counter, 13 second clock generation Device, 14 second arithmetic unit, 15 branch circuit, 16 first
Delay line, 17 second delay line, 18 Mth delay line,
19 AND circuit, 20 delay time selecting means, 21 pulse train generator, 22 gate circuit, 23 third counter, 24 third arithmetic unit, 25 OR circuit, 26 delay circuit, 27 combining circuit, 28 fourth counter, 29
3rd clock generator, 30 4th arithmetic unit, 31 2nd
Pulse train generator, 32 fifth counter, 33 fifth calculator.

Claims (8)

[Claims] 1. A laser transmitter for transmitting a laser pulse to a target and converting a part of the laser pulse into an electric signal to generate a start pulse, and an electric laser for receiving the laser pulse reflected by the target. A laser receiver that generates a stop pulse by converting the signal into a signal, a clock generator that generates a clock with a period T, receives the start pulse, starts counting the clock, receives the stop pulse, and stops counting the clock. And a calculator for receiving the count value N of the clock from the counter and receiving the distance R to the target by using the speed of light C as R = C · N · T / 2. Means for obtaining time Δt ₁ from the start pulse generation time until the counter counts the clock first after the start pulse is generated And means for obtaining a difference Δt ₂ between the stop pulse generation time and the time when the clock first arrives at the counter after the stop pulse is generated, and the computing unit using the obtained Δt ₁ and Δt _2. A laser distance measuring device characterized in that a distance to a target is obtained by R + C (Δt ₁ −Δt ₂ ) / 2 by means of correcting the obtained distance R. 2. As a means for obtaining the Δt ₁ , the T
Second generating a second clock having a shorter period T ₂
Second clock generator, receiving the start pulse, starting counting of the second clock, and stopping counting of the second clock by the clock from the clock generator that comes first after the start pulse is generated. Of the second counter and the count value N ₂ of the second counter and the T
_2. The laser distance measuring apparatus according to claim ₁ , wherein Δt ₁ is calculated by Δt ₁ = T ₂ · N ₂ using ₂ . 3. A means for branching the start pulse into a plurality of branch lines, a delay line installed on each of the plurality of branch lines and having a different delay time, as means for obtaining the Δt ₁ .
A means for obtaining a logical product of the start pulse delayed by the delay line and the clock from the clock generator is provided in each of the plurality of branch lines, and Δt _{1 is obtained} from the result of the logical product in each of the plurality of branch lines. 2. The laser distance measuring apparatus according to claim 1, wherein a delay time corresponding to is selected. 4. As a means for obtaining the Δt ₁ , the gate is opened by receiving the start pulse, the input signal is allowed to pass through, and the gate is closed by the clock from the clock generator which first arrives after the start pulse is generated. A gate circuit for interrupting an input signal, a means for delaying the start pulse one after another to generate a pulse train of a cycle T ₃ , and a third counter for counting the number of pulses passing through the gate circuit in the pulse train. And using the count value N ₃ of the third counter and T ₃ described above, Δt ₁
2. The laser range finder according to claim ₁ , wherein Δt ₁ = T ₃ · N ₃ is obtained. 5. The T as a means for obtaining the Δt ₂
A third clock generating a third clock with a shorter period T ₄ .
And a clock generator which receives the stop pulse, starts counting the third clock, and stops counting the third clock by the clock from the clock generator which comes first after the stop pulse is generated. Counter of the fourth counter and the count value N ₄ of the fourth counter and T
_4. The laser distance measuring apparatus according to claim 1, wherein Δt ₂ is calculated by Δt ₂ = T ₄ · N ₄ using ₄ . 6. A means for branching the stop pulse into a plurality of branch lines, a delay line provided on each of the plurality of branch lines and having different delay times, as means for obtaining the Δt ₂ .
A means for obtaining a logical product of the stop pulse delayed by the delay line and the clock from the clock generator is provided in each of the plurality of branch lines, and Δt _{2 is obtained} from the result of the logical product in each of the plurality of branch lines. 2. The laser distance measuring apparatus according to claim 1, wherein a delay time corresponding to is selected. 7. A means for obtaining the Δt ₂ is to open the gate by receiving the stop pulse to allow an input signal to pass therethrough, and to close the gate by a clock from the clock generator which comes first after the stop pulse is generated. A gate circuit for interrupting an input signal, a means for delaying the stop pulse one after another to generate a pulse train having a period T ₅ , and a fifth counter for counting the number of pulses of the pulse train passing through the gate circuit. Using the count value N ₅ of the fifth counter and T ₅ described above, Δt _2
2. The laser distance measuring apparatus according to claim 1, wherein Δt ₂ = T ₅ · N ₅ is obtained. 8. A laser transmitter for transmitting a laser pulse toward a target and converting a part of the laser pulse into an electric signal to generate a start pulse, and an electric laser for receiving the laser pulse reflected by the target. A laser receiver that generates a stop pulse by converting the signal into a signal, a clock generator that generates a clock with a period T, receives the start pulse, starts counting the clock, receives the stop pulse, and stops counting the clock. And a calculator for receiving the count value N of the clock from the counter and receiving the distance R to the target by using the speed of light C as R = C · N · T / 2. Design value f of clock frequency of clock generator
And a distance to the target is calculated by (1 + Δf / f) R by correcting the distance R calculated by the arithmetic unit using Δf as the manufacturing error.