JP2006053076A - Distance measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a distance measuring device in which the measurement resolution can be changed. <P>SOLUTION: The distance measuring device comprises: a transmission part (110) for transmitting a prescribed measurement signal toward an object to be measured; a receiving part (120) for receiving the signal returning from the direction of the object to be measured; and a control part (100') for executing the measurement process in which the transmission part and the receiving part are driven, for detecting the time from the transmission to the receiving of the measurement signal, on the basis of the signal received by the receiving part, and for making the resolution be variable when the receiving part receives the signal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a distance measuring apparatus that transmits a signal toward a measurement object and measures a distance to the distance measurement object from a time until a signal reflected by the measurement object returns. The present invention particularly relates to a distance measuring device that detects the timing at which the signal returns in a finite period.

FIG. 14 is a schematic configuration diagram of a conventional distance measuring device (Patent Document 1, Patent Document 2, etc.).
The conventional distance measuring device includes a transmission unit 110, a reception unit 120, a memory 130, a control unit 100, and the like. Reference numerals 141 and 142 are lenses, reference numeral 110a is a semiconductor laser, reference numeral 110b is a laser driving circuit, reference numeral 120a is a photodetector, reference numeral 120b is an amplifier, reference numeral 120c is a binarization circuit, reference numeral 120d is a light emission detection circuit, reference numeral 120e is a threshold setting circuit, 120f is a sampling circuit, 120g is a counter, and 120h is a transmitter.

The transmitter 110 transmits pulsed laser light (measurement optical signal) toward the object to be measured.
The receiving unit 120 periodically and periodically receives an optical signal returning from the direction of the distance measuring object. The received optical signals are stored in the memory 130, respectively.
This reception is synchronized with a predetermined clock (clock transmitted from the transmitter 120h).

The frequency of this clock is set in advance to a predetermined value sufficiently higher than the pulse width of the measurement optical signal (for example, 80 MHz with a pulse width of 30 nsec) so that the measurement optical signal can be reliably received.
The control unit 100 identifies the optical signal for measurement from each optical signal stored in the memory 130, recognizes the time from transmission to reception of the optical signal for measurement as a unit of reception, Is converted to distance.

In order to improve the distance measurement resolution in this distance measuring device, the clock frequency may be set high in advance so that the reception cycle is shortened. Since the speed c (light speed) of the optical signal is constant, for example, if the clock frequency is set to 80 MHz, the ranging resolution is about 2 m. If the clock frequency is set to 160 MHz, the ranging resolution is about 1 m. become.
US Pat. No. 5,760,887 JP 7-12935 A

However, the distance measurement resolution required of the distance measuring apparatus often changes depending on the distance measurement status (the type of distance measurement object, the distance to the distance measurement object, the distance measurement purpose, etc.).
Therefore, an object of the present invention is to provide a distance measuring device capable of changing the measurement resolution.

  The distance measuring device according to claim 1, a transmitting unit that transmits a predetermined measurement signal toward a distance measuring object, a receiving unit that receives a signal returning from the direction of the distance measuring object, and the transmitting unit And a measurement process for driving the receiving unit, and detecting a time from transmission of the measurement signal to reception based on the signal received by the receiving unit, and when the receiving unit receives the signal And a control unit that makes the resolution variable.

The distance measuring device according to claim 2 is the distance measuring device according to claim 1, wherein reception of the signal at the receiving unit is synchronized with a sample clock, and the control unit changes the sample clock. Thus, the resolution is made variable.
The distance measuring device according to claim 3 is the distance measuring device according to claim 2, wherein the control unit changes the frequency of the sample clock according to an instruction from the outside or the detected time. A sampling period length of the sample clock is changed in conjunction with a change in frequency so that the number of times of the sample clock is maintained at a predetermined value.

  The distance measuring device according to claim 4 is the distance measuring device according to claim 2, wherein the control unit first sets the frequency of the sample clock to a predetermined relatively low value and executes the measurement process. And recognizing the reception timing of the measurement signal based on the signal received by the reception unit, and if the recognized reception timing is within a range that can be covered by a reception period at the frequency of the sample clock, the sample clock The frequency is set to be relatively higher than the predetermined value, the measurement process is executed, and the time is detected based on the signal received by the receiving unit.

  The distance measuring device according to claim 5 receives a transmitter for transmitting a predetermined measurement signal toward the distance measuring object and a signal returning from the direction of the distance measuring object in synchronization with the sample clock. A receiving unit; and a control unit that performs measurement processing for driving the transmitting unit and the receiving unit, and detects a time from transmission of the measurement signal to reception based on a signal received by the receiving unit. In the distance measuring apparatus, the frequency of the sample clock is variable, and the control unit first sets the frequency of the sample clock to a relatively low predetermined value to execute the measurement process, and the receiving unit Based on the received signal, the reception timing of the measurement signal is recognized, and if the recognized reception timing is within a range that can be covered by the reception period at the frequency of the sample clock, the reception start timing is Offsetting the sampling time and setting the frequency of the sample clock relatively higher than the predetermined value to execute the measurement process, and detecting the time based on a signal received by the receiving unit. To do.

  The distance measuring device according to claim 6 receives a transmitter for transmitting a predetermined measurement signal toward the distance measurement object and a signal returning from the direction of the distance measurement object in synchronization with the sample clock. A receiving unit; and a control unit that performs measurement processing for driving the transmitting unit and the receiving unit, and detects a time from transmission of the measurement signal to reception based on a signal received by the receiving unit. In the distance measuring apparatus, the frequency of the sample clock is variable, and the control unit changes the frequency of the sample clock according to an instruction from the outside or the detected time, and also performs sampling of the sample clock. The number of sample clocks is changed in conjunction with the change of the frequency while keeping the period length at a predetermined value.

  According to the present invention, a distance measuring device capable of changing the measurement resolution is realized.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1, 2, 3, 4, 5, and 6.
The present embodiment is an embodiment of a distance measuring device to which the present invention is applied.

First, the configuration of the distance measuring apparatus according to the present embodiment will be described with reference to FIG. In FIG. 1, the same elements as those of the conventional distance measuring device shown in FIG.
As shown in FIG. 1, the distance measuring device of the present embodiment includes a transmission unit 110, a reception unit 120 ′, a memory 130, an MPU (corresponding to a control unit) 100 ′, and an operation unit 12. The distance measuring device also includes a display unit (not shown) for displaying information to the operator.

The transmitter 110 includes a lens 141, a semiconductor laser 110a, a laser drive circuit 110b, and the like.
The receiving unit 120 ′ includes a lens 142, a photodetector 120a, an amplifier 120b, a binarization circuit 120c, a light emission detection circuit 120d, a threshold setting circuit 120e, a sampling circuit 120f, a counter 120g, a transmitter 120h, a frequency division / multiplication circuit 11 Etc.

Next, distance measurement (consisting of measurement processing and calculation processing) by the distance measuring apparatus of the present embodiment will be described based on FIG. 1, FIG. 2, and FIG. A distance measurement instruction from the operator is input from the operation unit 12. The MPU 100 ′ performs distance measurement by driving each unit in accordance with the instruction.
(Measurement process)
The transmitter 120h generates a clock at a predetermined frequency. The frequency division / multiplication circuit 11 divides or multiplies the frequency of the clock. The division or multiplication ratio is preset by the MPU 100 ′. Depending on the ratio, the frequency of the clock output from the frequency division / multiplication circuit 11 can be switched between the values f _a , f _b and f _c (hereinafter, f _a = 160 MHz, f _b = 80 MHz, f _c). = 40 MHz). That is, the clock used for reception, which will be described later in this distance measuring device (hereinafter, "sample clock" that.) Frequency f of is switchable between the value f _a, f _b, f _c.

The threshold setting circuit 120e generates a threshold (a threshold corresponding to an intermediate intensity between the intensity of background light measured in advance and the intensity of the measurement optical signal transmitted from the transmitter 110), and the threshold is set to the binarization circuit 120c. (FIG. 1 (1)).
The MPU 100 ′ drives the counter 120g (FIG. 1 (2)). That is, the counter 120g is designated with an upper limit value N (here, N = 250) and starts counting. The MPU 100 ′ instructs the laser drive circuit 110b to emit a pulsed measurement optical signal (FIG. 1 (3)).

The counter 120g starts counting in synchronization with the sample clock and gives a signal to start reception (sample enable signal) to the sampling circuit 120f.
The laser drive circuit 110b drives the semiconductor laser 110a. As a result, a measurement optical signal is transmitted to the distance measuring object via the lens 141.
The light emission detection circuit 120d detects the timing of this transmission and gives a start pulse signal to the sampling circuit 120f (FIG. 1 (4)).

Light incident on the lens 142 from the direction of the object to be measured is guided to the photodetector 120a and converted into an electrical signal.
The electric signal is input to the binarization circuit 120c via the amplifier 12b. The binarization circuit 120c discriminates an electric signal with a threshold value and converts it into a binarized signal.
When the sample enable signal is given, the sampling circuit 120f repeatedly receives the binarized signal in synchronization with the sample clock (FIG. 1 (5)), and stores the received signal (detection signal) in the memory 130. (Note that the signal detection method may be either edge sampling or level sampling.)

When the count value reaches the upper limit value N, the counter 120g gives a signal of completion of reception to the sampling circuit 120f.
Therefore, the sampling circuit 120f receives the detection signal N times at the frequency f of the sample clock. The N detection signals received at this time are individually stored in N storage areas mem1, mem2,..., MemN on the memory 130 as shown in FIG.

FIG. 2 is a block diagram in which the operations of the sampling circuit 120f, the counter 120g, and the memory 130 are visualized. FIG. 3 shows a timing chart visualizing the transmission timing, reception timing, and detection signal reception timing of a measurement optical signal in a certain distance measurement.
Here, in order to improve the ranging accuracy, the above transmission and reception are performed a plurality of times (the number m of transmissions, here, m = 250) as shown in FIG. At this time, (N × m) detection signals are acquired.

These (N × m) detection signals are accumulated on the storage areas mem1, mem2,..., MemN of the memory 130 at each reception timing (see FIG. 2).
Therefore, the storage area of the memory 130 mem1, mem2, · · ·, the memn, integrated value S ₀ of the m component of the detection _{signal, ···, S (N-1} ) are stored, respectively.
By the way, since the information amount of the detection signal which is a binarized signal is 1 bit and the number of transmissions is m = 250, the capacity of each storage area mem1, mem2,. It becomes. Therefore, here, the total capacity of the memory 130 is set to 8 bits × 250 = 250 bytes (measurement processing).

(Calculation processing)
Each integrated value S ₀ obtained in the measurement process described _{above, ···, S (N-1} ) Among, as shown in the lower part of FIG. 3, an integrated value S ₀ of the start pulse signal, for measurement In addition to the integrated value S _i of the optical signal, the integrated value of the noise signal is also included.
However, the integrated value of the noise signal is generally a sufficiently small value as compared with the integrated value S ₀ of the start pulse signal and the integrated value S _i of the measurement optical signal. The count value of the reception timing of the start pulse signal is a predetermined value (here, 0).

Therefore, the MPU 100 ′ obtains the maximum value among the integrated values S ₁ ,..., S _(N−1) , regards the detection signal that gives the maximum value S _i as the measurement optical signal, and performs the measurement. The count value i of the reception timing of the optical signal for use is recognized.
The count difference Δ (here, Δ = i) between the count value i of the reception timing of the measurement optical signal and the count value of the reception timing of the start pulse signal (here, 0) is from transmission to reception of the measurement optical signal. Time Δt, that is, the distance to the object to be measured.

The MPU 100 ′ converts the count difference Δ into a distance (distance = Δ · (c / f) · (1/2), where c is the speed of light) and displays it on a display unit (not shown).
Note that when the frequency f of the sample clock is a high value f _a (here, 160 MHz), the reception period (= one unit of count) becomes small, and thus the ranging resolution becomes high (here, about 1 m).

Further, when the frequency f of the sample clock is an intermediate value f _b (80 MHz), the ranging resolution is intermediate (here, about 2 m).
Further, when the frequency f of the sample clock is a low value f _c (here, 40 MHz), the ranging resolution is low (here, about 4 m) (the calculation process).
Next, each mode of the distance measuring apparatus according to the present embodiment will be described with reference to FIGS. 3, 4, 5, and 6. FIG.

  The distance measuring apparatus of the present embodiment is switched between two modes, that is, a manual mode and an automatic mode by an operator. When the distance measuring apparatus is in the automatic mode, the distance measuring resolution is automatically switched between three types of distance measuring resolutions (“low”, “medium”, and “high”). The mode switching instruction and the ranging resolution switching instruction from the operator are respectively input from the operation unit 12 shown in FIG.

(Manual mode)
3, 4, and 5 are timing charts (outline) of the distance measuring device in the manual mode. 3 is a timing chart when the ranging resolution is set to “high”, FIG. 4 is set to “medium”, and FIG. 5 is a timing chart when the ranging resolution is set to “low”. In each figure, the upper stage is the transmission timing of the measurement optical signal, the middle stage is the reception timing, and the lower stage is the reception timing of the detection signal. Further, in the lower part of each figure, a graph of each integrated value S ₀ ,..., S _(N−1) is shown. 3, 4, and 5 show only the outline of each timing, and the reception frequency and the like are shown more coarsely than actual for simplicity.

When the operator specifies the distance measurement resolution "high", the MPU 100 ', as shown in FIG. 3, the frequency f of the sample clock is set to f _a high distance measurement resolution (here approximately 1m) to set the .
When the operator designates the ranging resolution “medium”, as shown in FIG. 4, the MPU 100 ′ sets the frequency f of the sample clock to f _b and sets a medium ranging resolution (here, about 2 m). Set.

When the operator specifies the distance measurement resolution "low", the MPU 100 ', as shown in FIG. 5, the frequency f of the sample clock is set to f _c lower distance measurement resolution (here approximately 4m) to set the .
Then, as shown in FIGS. 3, 4, and 5, the MPU 100 ′ has a count value upper limit N (() regardless of whether the ranging resolution is “high”, “medium”, or “low”. Here, 250) is fixed. At this time, the frequency f is f _a of the sample clock, f _b, in conjunction with being changed between f _c, while the reception period length (period length of the sampling) T is T _a, T _b, T _c in is changed, the maximum distance measurement length _{L a, L b, L c} (250m here, 500 meters, 1000 m) is changed between (see FIGS. 3, 4, 5).

Therefore, the number of received detection signals (the number of samplings, that is, the amount of calculation) remains the same as the capacity of the memory 130 (here, 250 bytes).
Therefore, in the manual mode, even if the operator changes the ranging resolution between high, medium, and low (about 1 m, about 2 m, and about 4 m), the calculation amount in the distance measuring apparatus is as much as the capacity of the memory 130. (Here, 250 bytes) is automatically maintained, and the distance measurement time is also automatically maintained.

  In other words, in the manual mode, the memory 130 has a small capacity (250 bytes in this case), and the distance can be measured with a high distance measurement resolution (about 1 m here) for a short distance measurement time (the distance measurement resolution “high”). ”, And the capacity of the memory 130 is small (here, 250 bytes), and the distance measurement time is short, the distance can be measured with a long maximum distance measurement length (here, 1000 m) (ranging resolution“ When “low”.)

In this manual mode, if a high distance measurement resolution (about 1 m in this case) is set, the reception period length T is shortened, so that the maximum distance measurement length is shortened (here, 250 m) (see FIG. 3). However, in general, it is often a short distance measurement that requires a high ranging resolution, so that there is not much inconvenience.
(auto mode)
FIG. 6 is an operation flowchart of the distance measuring apparatus in the automatic mode.

First, the MPU 100 ′ sets the frequency f of the sample clock to a low value f _c (here, 40 MHz) and the upper limit value N of the count value to N (here, 250), and executes measurement processing in that state.
That is, first, the distance of the object to be measured is measured relatively coarsely with the longest maximum distance measurement length (here 1000 m) and the lowest distance measurement resolution (here about 4 m).

Then, the MPU 100 ′ obtains the count value i of the reception timing of the measurement optical signal based on each integrated value S ₀ ,..., S _(N−1) obtained by the measurement process (step S1). ).
Then, MPU 100 ', based on the count value i, if the reception timing receiving period length T _a of the measurement light signal were within the range below the upper limit value N of the count value sample clock as it The frequency f is changed to _a high value f _a (here, 160 MHz), and ranging is performed in this state.

That is, when it is determined that the distance of the distance measurement object is short (here, within 250 m) (YES in step S2), the maximum distance measurement length is shortened to the shortest (here, 250 m) and the maximum distance measurement resolution (about 1 m). ) To measure the distance closely (step S3).
In addition, when the reception timing of the measurement optical signal is within the range of the reception period lengths T _{a to} T _b , the MPU 100 ′ sets the frequency f of the sample clock to a medium level while keeping the upper limit value N of the count value. The value is changed to the value f _b (80 MHz here), and the distance is measured in that state.

That is, when it is determined that the distance of the object to be measured is medium (250 to 500 m in this case) (YES in step S4), the maximum distance measurement length is shortened to medium (500 m), and medium distance measurement resolution ( The distance is measured at about 2 m) (step S5).
Further, MPU 100 ', when the reception timing of the measuring light signal was later than the reception period length T _b performs arithmetic processing based on the reception timing.

That is, when it is determined that the distance of the distance measurement object is long (here, 500 to 1000 m) (NO in step S4), the maximum distance measurement length cannot be shortened, and therefore the distance measurement object from the measurement result (i) in step S1. The distance to the object is obtained and displayed (step S6).
Therefore, in the automatic mode, the highest ranging resolution (about 1 m, about 2 m, about 4 m) is automatically set in a range where the small capacity of the memory 130 (here, 250 bytes) is not insufficient.

In this automatic mode, the ranging resolution automatically changes depending on the distance of the object to be measured. Therefore, the MPU 100 ′ sets the ranging resolution being set to “about 1 m”, “about 2 m”, “about 4 m”, etc. And may be displayed on a display unit (not shown).
[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described with reference to FIGS. 7, 8, 9, and 10.

The present embodiment is an embodiment of a distance measuring device to which the present invention is applied. Here, only differences from the distance measuring apparatus of the first embodiment will be described.
The configuration of the distance measuring apparatus of the present embodiment is as shown in FIG. In FIG. 7, the same elements as those of the distance measuring apparatus according to the first embodiment shown in FIG.
As is apparent from FIG. 7, the counter 21 of the distance measuring device of the present embodiment has two counters 21a and 21c.

As shown in FIG. 8, two types of clocks having frequencies f _a and f _c synchronized with each other are output from the frequency division / multiplication circuit 11 ′ (hereinafter, f _a = 160 MHz and f _c = 40 MHz). ).
Frequency f of the sample clock applied to the counter 21a is a high value f _a, the frequency f of the sample clock applied to the counter 21c is low f _c.
Next, distance measurement in the distance measuring apparatus according to the present embodiment will be described with reference to FIGS.

9 and 10 are (schematic) timing charts of the distance measuring device of the present embodiment. In each figure, the upper stage is the transmission timing of the measurement optical signal, the middle stage is the reception timing, and the lower stage is the reception timing of the detection signal. Further, in the lower part of each figure, a graph of each integrated value S ₀ ,..., S _(N−1) is shown. In FIGS. 9 and 10, only the outline of each timing is shown, and the reception frequency and the like are shown coarser than the actual ones for simplicity.

First, the MPU 100 ″ drives the counter 21c, and as shown in FIG. 9, the upper limit value N of the count value is set to N (here, 250), and reception is performed with a sample clock having a low frequency f _c (here, 40 MHz). The MPU 100 ″ recognizes the count value i of the reception timing of the measurement optical signal (count difference Δ _i from transmission to reception of the measurement optical signal) based on the integrated value S ₀ ,. (Refer to the lower part of FIG. 9).

That is, first, the distance to the object to be measured is roughly measured with the longest maximum distance measurement length (here 1000 m) and the lowest distance measurement resolution (here about 4 m).
Next, the MPU 100 ″ drives the counter 21c and, as shown in FIG. 10, does not start reception immediately but continues counting only until the count value becomes (i−1). When (i-1) is reached, the counter 21a is driven (see FIG. 8 (1)), and reception is performed with a sample clock having _a high frequency fa (160 MHz in this case). The MPU 100 ″ is obtained by this reception. Based on the integrated value (S ₀ ,...), The count value j of the reception timing of the measurement optical signal (count difference Δ _j from the start of counting by the counter 21a to the reception of the measurement optical signal) is recognized ( (See the lower part of FIG. 10).

That is, the distance to the object to be measured is remeasured (densely remeasured) with a high distance measurement resolution (about 1 m in this case).
Here, the upper limit (number of receptions) N of the count value of the counter 21a does not need to be large, and is equal to or greater than the value corresponding to the period of the count values (i−1) to (i + 1) of the counter 21c (here, 8). .)

Next, the MPU 100 ″ obtains the distance to the distance measurement object with high distance measurement resolution based on the count difference Δ _i recognized in the first measurement and the count difference Δ _j recognized in the remeasurement.
However, as described above, the distance measurement resolution of the first measurement is low (about 4 m here), and the distance measurement resolution of the remeasurement is high (about 1 m here). In addition, the start timing of remeasurement reception is offset.

Therefore, the MPU 100 ″ considers the difference between the units and the offset amount, and sets the distance, for example, distance = (Δ _i −1) · (c / f _c ) + Δ _j · (c / f _a ) ( However, it calculates | requires by formulas, such as c: light speed) etc. And the calculated | required distance is displayed on a display part not shown.
As described above, in the first measurement, since the distance measurement resolution is set low (about 4 m in this case), the amount of calculation is minimized.

In the re-measurement, the reception start timing is offset, and the reception period is limited to a few counts (here, 8 counts) before and after the reception timing recognized in the first measurement. The amount of computation is minimized.
Therefore, the capacity of the memory 130 can be reduced (250 bytes here).
Therefore, in the distance measuring apparatus according to the present embodiment, the memory 130 has a small capacity (here, 250 bytes), but the distance measurement is performed with a high distance measuring resolution (here, about 1 m) and a long maximum distance measuring length (here, 1000 m). Distance is done.

[Third Embodiment]
Hereinafter, the third embodiment of the present invention will be described with reference to FIGS. 11, 12, and 13.
The present embodiment is an embodiment of a distance measuring device to which the present invention is applied. Here, only differences from the distance measuring apparatus of the first embodiment will be described.
The configuration of the distance measuring apparatus of the present embodiment is the same as that of the first embodiment shown in FIG. However, here, the capacity of the memory 130 is assumed to be 500 bytes.

In addition, the distance measuring apparatus operates in a manual mode of a type different from the manual mode of the first embodiment. In the distance measuring apparatus, the distance measuring resolution is switched between three types of distance measuring resolutions (low, medium, and high) by the operator. The switching instruction from the operator is input from the operation unit 12 shown in FIG.
11, 12, and 13 are timing charts (outline) of the distance measuring apparatus according to the third embodiment. FIG. 11 is a timing chart when the ranging resolution is set to “high”, FIG. 12 is set to “medium”, and FIG. 13 is a timing chart when the ranging resolution is set to “low”. In each figure, the upper stage is the transmission timing of the measurement optical signal, the middle stage is the reception timing, and the lower stage is the reception timing of the detection signal. Further, in the lower part of each figure, a graph of each integrated value S ₀ ,..., S _(N−1) is shown. 11, 12, and 13 show only the outline of each timing, and the reception frequency and the like are described more coarsely than actual for simplicity.

When the operator specifies the distance measurement resolution "high", the MPU 100 ', as shown in FIG. 11, the frequency f of the sample clock is set to f _a high distance measurement resolution (here approximately 1m) to set the .
When the operator designates the ranging resolution “medium”, as shown in FIG. 12, the MPU 100 ′ sets the frequency f of the sample clock to f _b and sets the medium ranging resolution (here, about 2 m). Set.

When the operator specifies the distance measurement resolution "low", the MPU 100 ', as shown in FIG. 13, the frequency f of the sample clock is set to f _c lower distance measurement resolution (here approximately 4m) to set the .
Then, as shown in FIGS. 11, 12, and 13, the MPU 100 ′ fixes the reception period length T regardless of whether the ranging resolution is “high”, “medium”, or “low”. Thus, in conjunction with the change of the frequency f of the sample clock between f _a , f _b and f _c , the upper limit value N of the count value is set to N _a , N _b , N _c (here, 500, 250, 125). At this time, the amount of computation is (11, 12, see FIG. 13) to change between the (500 bytes, 250 bytes, 125 bytes, _{here) M a, M b, M} c.

Therefore, the maximum distance measurement length remains unchanged at a distance corresponding to the reception period length T (here, 1000 m).
Therefore, in the distance measuring apparatus according to the third embodiment, even if the operator changes the distance measuring resolution between high, medium, and low (about 1 m, about 2 m, and about 4 m), the maximum length measurement is the reception period length T. Is automatically maintained at a distance corresponding to (1000 m in this case).

  In other words, in the distance measuring apparatus according to the third embodiment, the distance can be measured with a high distance measurement resolution (about 1 m) for a long maximum distance measurement length (here, 1000 m) (ranging resolution “high”). In addition, for a long maximum distance measurement length (here, 1000 m), it is possible to perform distance measurement with a small amount of computation (here, 125 bytes), that is, a short distance measurement time (ranging resolution “low”). When.).

In the distance measuring apparatus according to the third embodiment, if a high distance measuring resolution (about 1 m in this case) is set, the amount of calculation increases (here, 500 bytes), resulting in a long distance measuring time. However, an increase in waiting time when a high distance measurement resolution is required is acceptable for many operators, so that inconvenience does not occur much.
[Others]
As the frequency divider / multiplier circuits 11 and 11 ′ of the distance measuring apparatus of each of the above embodiments, either a frequency divider circuit or a frequency multiplier circuit may be applied as long as it can generate sample clocks having a plurality of types of frequencies.

In addition, the types of sample clocks in the distance measuring apparatuses according to the first and third embodiments may be increased to four or more.
The function of the distance measuring device of the second embodiment may be incorporated in the distance measuring device of the first embodiment or the distance measuring device of the third embodiment.

It is a schematic block diagram of the ranging device of 1st Embodiment. It is the block diagram which visualized each operation | movement of the sampling circuit 120f, the counter 120g, and the memory 130 of the distance measuring device of 1st Embodiment. 6 is a timing chart of the distance measuring device according to the first embodiment (in the case of manual mode and distance measurement resolution “high”). 3 is a timing chart of the distance measuring device according to the first embodiment (in the case of manual mode and distance measurement resolution “medium”). 3 is a timing chart of the distance measuring device according to the first embodiment (in the case of manual mode and distance measurement resolution “low”). It is an operation | movement flowchart of the distance measuring device of 1st Embodiment (in the case of automatic mode). It is a schematic block diagram of the ranging device of 2nd Embodiment. It is the block diagram which visualized each operation | movement of the sampling circuit 120f, the counters 21a and 21c, and the memory 130 of the distance measuring device of 2nd Embodiment. It is a timing chart of the distance measuring device of 2nd Embodiment (1st measurement). It is a timing chart of the distance measuring device of 2nd Embodiment (remeasurement). It is a timing chart of the distance measuring device of 3rd Embodiment (in the case of distance measurement resolution "high"). It is a timing chart of the distance measuring device of 3rd Embodiment (in the case of distance measurement resolution "medium"). It is a timing chart of the distance measuring device of 3rd Embodiment (when distance measurement resolution is "low"). It is a schematic block diagram of the conventional ranging device.

Explanation of symbols

11, 11 'Frequency dividing / multiplication circuit 12 Operation unit 110 Transmission unit 120, 120' Reception unit 130 Memory 100, 100 ', 100 "MPU
141, 142 Lens 110a Semiconductor laser 110b Laser drive circuit 120a Photo detector 120b Amplifier 120c Binarization circuit 120d Light emission detection circuit 120e Threshold setting circuit 120f Sampling circuit 120g, 21, 21a, 21c Counter 120h Transmitter

Claims (6)

A transmitter for transmitting a predetermined measurement signal toward the object to be measured;
A receiver for receiving a signal returning from the direction of the object to be measured;
Measurement processing for driving the transmitter and the receiver is executed, and a time from transmission to reception of the measurement signal is detected based on a signal received by the receiver, and the receiver receives the signal. And a control unit that makes the resolution variable when performing the measurement. The distance measuring device according to claim 1,
Reception of the signal at the receiver
Synchronized with the sample clock,
The controller is
A ranging apparatus characterized in that the resolution is made variable by changing the sample clock. The distance measuring device according to claim 2,
The controller is
The frequency of the sample clock is changed according to an external instruction or the detected time, and the sampling clock is sampled in conjunction with the change of the frequency so that the number of times of the sample clock is maintained at a predetermined value. A distance measuring device characterized by changing a period length. The distance measuring device according to claim 2,
The controller is
First, the measurement processing is performed by setting the frequency of the sample clock to a relatively low predetermined value, and the reception timing of the measurement signal is recognized based on the signal received by the reception unit,
If the recognized reception timing is within a range that can be covered by the reception period at the sample clock frequency, the measurement processing is performed by setting the frequency of the sample clock relatively higher than the predetermined value, and the reception A distance measuring device that detects the time based on a signal received by a unit. A transmitter for transmitting a predetermined measurement signal toward the object to be measured;
A receiver for receiving a signal returning from the direction of the distance measurement object in synchronization with a sample clock;
A distance measuring apparatus comprising: a control unit that performs measurement processing for driving the transmission unit and the reception unit, and detects a time from transmission of the measurement signal to reception based on a signal received by the reception unit In
The frequency of the sample clock is variable,
The controller is
First, the measurement processing is performed by setting the frequency of the sample clock to a relatively low predetermined value, and the reception timing of the measurement signal is recognized based on the signal received by the reception unit,
If the recognized reception timing is within a range that can be covered by the reception period at the sample clock frequency, the reception start timing is offset and the sample clock frequency is set relatively higher than the predetermined value. The distance measuring device is configured to execute the measurement process and detect the time based on a signal received by the receiving unit. A transmitter for transmitting a predetermined measurement signal toward the object to be measured;
A receiver for receiving a signal returning from the direction of the distance measurement object in synchronization with a sample clock;
A distance measuring apparatus comprising: a control unit that performs measurement processing for driving the transmission unit and the reception unit, and detects a time from transmission of the measurement signal to reception based on a signal received by the reception unit In
The frequency of the sample clock is variable,
The controller is
The frequency of the sample clock is changed according to an instruction from the outside or the detected time, and the number of times of the sample clock is interlocked with the change of the frequency while keeping the sampling period length of the sample clock at a predetermined value. Ranging device characterized by changing.

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