JP2003130954A - Range finder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly accurate range finder properly holding the contrast of reflected light depending on a measuring environment such as the weather, a geographic factor or the like with noise light. SOLUTION: The unsuitableness of the contrasts of measuring reflected lights under various environments with noise light is set off by optimizing various measuring parameters related to measurement to enable the optimum measurement even under any environment. Therefore, the reflected light from an object to be measured and noise light arriving at random can be separated accurately and the highly accurate measurement of a spaced-apart distance (range-finding) becomes possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring device and method for measuring a distance to an object to be measured in a non-contact manner using a laser beam or the like.

[0002]

2. Description of the Related Art As such a distance measuring device, a process of emitting pulsed measuring light (for example, laser light) toward an object to be measured and receiving reflected light reflected from the object to be measured. It is known that the time is measured and the distance to the object to be measured is obtained based on the elapsed time and the propagation speed of the laser light. However, when irradiating the DUT with the laser pulsed light and receiving the reflected light from the DUT in this way, not only the reflected light of the laser light but also the natural light or the like is received and the natural light or the like becomes noise light. Therefore, there is a problem that it is difficult to distinguish the reflected light from the measured object and the noise light, and it is difficult to measure the distance accurately.

By the way, when performing such distance measurement,
As long as the position of the object to be measured does not change, the reflected light from the object to be measured is always received after a certain time from the emission of the measuring light, whereas the light receiving timing of the noise light is random. Therefore, pulsed measuring light is repeatedly emitted toward the object to be measured, and when each reflected light satisfies a predetermined condition, a frequency count is performed corresponding to the distance, and all the repeating measuring light is emitted. The frequency distribution table (histogram) corresponding to the distance is created by integrating the frequencies counted in the emission of the, and the distance at which the total number of count frequencies in this frequency distribution table is the largest is the distance to the DUT. Is proposed.

In the frequency distribution table created as described above, the reception timing of the reflected light from the object to be measured is always constant, and the count frequency at the distance indicating this position is large. However, since the reception timing of the noise light is random, the frequency count is performed corresponding to various different distances for each repeated frequency count, and the integrated count frequency at each distance in the frequency distribution table becomes small. Therefore, if the distance to the object to be measured is the distance corresponding to the point where the frequency in the frequency distribution table created as described above becomes large (for example, the point exceeding a predetermined threshold value), randomly generated noise light is generated. By removing the effect of, it becomes possible to measure the distance more accurately.

[0005]

However, for example, at the seaside during fine weather, strong noise light exists in all directions and time intervals, making it difficult to distinguish the reflected light from the object to be measured and the noise light. Alternatively, when it is raining, reflected light from a distance is attenuated by raindrops, which may also make it difficult to distinguish it from noise light.

Further, since the noise light at night is generally low in intensity and the reflected light from the object to be measured is high in intensity, the difference becomes clear when the frequency distribution table is created.
It is possible to measure distances with higher accuracy than in fine weather or during rainfall. However, there is a problem of poor performance balance with measurement accuracy during fine weather, rain, etc., deterioration of elements such as light emitting elements, and disadvantageous in terms of power consumption.

The present invention has been made in view of the above problems, and provides a distance measuring device having a high measurement accuracy or a good balance of measurement accuracy regardless of the measurement environment such as weather.
Alternatively, it is an object of the present invention to provide a distance measuring device that has a long device life or battery life as a derivative.

[0008]

In order to achieve such an object, a distance measuring apparatus according to the present invention includes a measuring light emitting device for emitting a pulsed measuring light toward an object to be measured and an object to be measured. A reflected light receiver that receives the reflected light that is reflected, a distance calculator that determines the distance to the DUT based on the elapsed time from when the measurement light is emitted until the reflected light is received, and the measurement It is configured to include a controller that changes measurement parameters according to the environment.

The measurement environment may be manually input by the measurer.

Further, it may be configured such that preliminary light emission is performed by the measurement light emitting device and the measurement environment is obtained by the preliminary light emission.

Further, the controller stores typical measurement patterns corresponding to some typical measurement environments, and estimates the measurement environment by comparing the measurement pattern obtained by preliminary light emission with the typical measurement pattern. It may be configured as follows.

Here, the measurement parameter is 1 when the emission intensity of the measurement light emitted from the measurement light emitting device, the light receiving sensitivity of the reflected light receiving device, and the separation distance is calculated from the frequency distribution of the multiple measurements. It may be at least one of an intensity threshold for the intensity of the reflected light for one measurement and a determination threshold for the frequency distribution when the separation distance is obtained from the frequency distribution.

According to the distance measuring apparatus of the present invention having such a configuration, the intensity of the reflected light is changed by changing the emission intensity of the measurement light emitter according to the measurement environment, and the reflected light receiver receives light. Appropriate judgment is made by changing the sensitivity to change the count of received light, changing the intensity threshold for reflected light to change the frequency of the frequency distribution table, and changing the judgment threshold for the frequency distribution when calculating the distance. The distance can be determined. That is, by optimizing various measurement parameters related to these measurements, it is possible to adjust the contrast between the measurement reflected light and the noise light under various environments, and perform suitable measurement under various environments. Therefore, the reflected light from the object to be measured and the noise light coming randomly can be accurately separated, which enables highly accurate separation distance measurement (distance measurement).

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. A distance measuring device 1 according to the present invention is shown in FIG. The distance measuring device 1 is configured to have a laser light emitter 3 and a reflected light receiver 4 in a housing 2, and pulsed laser light (measurement light) is emitted from the laser light emitter 3. The housing 2 is provided with a laser light emitting window 3a and a reflected light receiving window 4a for receiving reflected light. On the upper surface of the housing 2, a first operation button 5 for powering on / off and a distance measurement start operation, and a second operation button 6 for selecting an operation mode and manual input are provided. A finder window 2a (see FIG. 3) is provided on the back surface of the housing 2, and an operator who performs distance measurement using the distance measuring device 1 looks at the object to be measured through the finder window 2a and the object to be measured. It is designed to measure the distance to.

FIG. 2 shows a schematic internal configuration of the distance measuring device 1. In addition to the above configuration, a controller 7 having a distance calculator 10 and a measurement parameter setting section 20 and a display signal from the controller 7 are provided. In response to this, a display 8 for displaying a distance is provided. The distance calculator 10 includes a counting unit 11, a table creating unit 12, a distance determining unit 13, and a distance selecting unit 14. On the other hand, the measurement parameter setting unit 20 includes an emission intensity setting unit 21 and a light receiving sensitivity setting unit 2
2, the intensity threshold value setting unit 23 and the determination threshold value determination unit 24. The contents of the distance calculator 10 and the measurement parameter setting unit 20 will be described later. The display 8 displays the operation mode and the distance inside the finder window 2a, and when the measurer looks into the finder window 2a, the operation mode (selection) and the distance are displayed within the field of view. It should be noted that a display for performing liquid crystal display may be provided outside the housing 2. Operation signals from the first and second operation buttons 5 and 6 are input to the controller 7. The laser light emitter 3 is composed of a pulse generation circuit 31, a light emitting element (semiconductor laser) 32 and a collimating lens 33. The reflected light light receiver 4 includes a receiving circuit 41, a light receiving element (eg APD: avalanche photodiode) 42 and a collector. It is composed of an optical lens 43.

An operation and an operation when the distance to the object to be measured is measured by using the distance measuring device 1 configured as described above will be described. Here, as an example of the measurement, as shown in FIG. 3, a case will be described in which the distance measuring device 1 is used to measure the distance to a distant object OB. Ranging device 1
When measuring the distance to the object to be measured OB using
First, as shown in FIG. 3, the measurer operates the first operation button 5 while looking at the object to be measured OB through the finder 2a.

As a result, the power is turned on, and then the operation mode is selected by the second operation button 6. The operation mode is a manual mode in which the operator manually selects one of three weather conditions: rain, rain, and night, depending on the measurement environment at the time of measurement, and preliminary light emission to estimate the measurement environment and set the measurement parameters. Optimized preliminary light emission mode 2
There is one.

Hereinafter, the embodiment of the present invention in the manual mode will be referred to as a first embodiment, and the embodiment in the preliminary light emission mode will be referred to as a second embodiment. Before specifically describing the first and second embodiments, a distance measuring method using a conventional laser distance measuring apparatus common to both embodiments will be described below based on flowcharts shown in FIGS. 4 and 5. .
In the flows shown in FIG. 4 and FIG. 5, the circled portions B are connected to each other to constitute one flow.

In the laser distance measuring device, when the operation signal from the first operation button 5 is further input to the controller 7 while the power is on, the distance measuring operation is started.
In response to this, the preprocessing shown in step S4 is performed, and the initialization processing such as clearing each memory is performed.

Next, the measurement timer is started once (step S6), and the intensity threshold TL is set (step S6).
8, FIG. 6 (A)). Then, the timer counter is started (step S10) and the controller 7
Causes the pulse generation circuit 31 to operate to emit a pulsed laser beam from the light emitting element 32 (step S1).
2). This laser light passes through the collimator lens 33 and is emitted from the laser emission window 3a toward the object to be measured (the laser light indicated by the arrow A in FIGS. 2 and 3).

The laser light A emitted from the distance measuring device 1 in this manner is applied to the object to be measured OB. The laser light applied to the object to be measured OB is reflected here as shown by an arrow B. Then, as shown by arrow B, the object to be measured O
Part of the reflected light reflected by B (light reflected toward the distance measuring device 1) enters the reflected light receiving window 4a (see arrow B in FIG. 2) and is collected by the condenser lens 43. The light is received and applied to the light receiving element 42. When the light receiving element 42 is thus irradiated with the reflected light, it sends a signal corresponding to the intensity of the reflected light to the receiving circuit 41, and the receiving circuit 41 amplifies this signal and sends it to the controller 7.

In this way, the controller 7 receives the reflected light signal as shown in FIG. 6A1 (step S14), and the distance calculator 10 uses the received signal to measure the object OB as follows. Measure the distance to. In FIG. 6 (A1), the horizontal axis indicates the elapsed time with the point of emission of the pulsed laser light from the laser light emitter 3 as the origin, and the vertical axis indicates the intensity of the reflected light received. That is, FIG. 6A1 shows step S1.
2 shows the change over time in the intensity of the reflected light received by the reflected light receiver 4 from the time when the pulsed laser light is emitted from the laser light emitter 3.

When such reflected light is detected, a point where the reflected light intensity exceeds the intensity threshold value TL set in step S8 is searched for, and the time zone in which the point is located is recorded (step S16). This time zone is finely divided and formed at constant time intervals (for example, 12.5 ns) as shown in FIG. 6B, based on the count of the timer counter started in step S10. Therefore, for example, in the case of the reflected light intensity shown in FIG. 6 (A1), in the time zone including the positions of the peaks P11 to P17 that exceed the intensity threshold value TL shown by the alternate long and short dash line in FIG. A flag is set as shown in the first column, and the time zones Z5, Z in which this flag is set are set.
6, Z8, Z11, Z16, Z17, Z18 are recorded in step S16.

Here, the elapsed time from when the pulsed laser light is emitted from the laser light emitter 3 to when the reflected light is received by the reflected light receiver 4 is a distance using the spatial propagation velocity of the laser light. Can be converted to and the above time zone is converted to the corresponding distance zone. And
As shown in FIG. 7, the count unit 11 included in the distance calculator 10 of the controller 7 controls the distance zones Z1, Z
In the count table formed corresponding to 2 ..., One frequency is added and recorded in each of the distance zones for which the flag is set (step S18). In the case of the first time mentioned above, the distance zones Z5, Z6, Z8, Z11, Z1.
One frequency is recorded in each of 6, Z17 and Z18.

In this example, the object OB to be measured is in the vicinity of the distance zone Z16 (located in the long distance area). Therefore, the peak P1 in FIG.
It is considered that 5, P16 and P17 are reflected light from the target object OB, and other peaks P11, P12, P13 and P14 are those in which natural light or the like is detected as noise light.

Further, in this example, the flow of steps S6 to S18 is configured to be repeated 520 times in total, and it is determined in step S20 whether the measurement of 520 times has been completed. At the stage where the first pulse laser irradiation is performed as described above, step S22
The process proceeds to step S24 and waits for the one-time measurement timer (for example, 1 ms has elapsed) to proceed to step S24 to stop the one-time measurement timer.

Then, the process proceeds to step S6 again to restart the one-time measurement timer to start the second measurement by the pulse laser irradiation. Thereafter, similarly to the first time, the intensity threshold TL is set (step S8), the timer counter is started (step S10), the pulsed laser light is emitted (step S12), and the reflected light is received (step S14). ). FIG. 6 (A2) shows the change in intensity of the reflected light received with respect to the second irradiation of the pulsed laser light as described above. Also in this case, the intensity threshold value T set in step S8
A time zone including the positions of peaks P21 to P25 exceeding L is flagged as shown in the second column in FIG. 6B, and the time zones Z5, Z6, Z10 Z14 and Z15 are step S16
Recorded in.

Then, in step 18, as in the case of the first irradiation of the pulsed laser beam, one frequency is added and recorded in each of the distance zones flagged in the count table shown in FIG. In this case, one frequency is additionally recorded in each of the distance zones Z5, Z6, Z10, Z14, and Z15.
Since 1 and 5 are recorded in 5 and Z6, the recording frequency in these distance zones is 2.

FIG. 7 shows the frequency of the count table when 520 irradiations of pulsed laser light are performed at intervals of a set time (for example, 1 ms) of the one-time measurement timer. When the irradiation of the pulsed laser light 520 times is completed in this way, the process proceeds to step S26, and the moving average process of the count frequency in each distance zone is performed. This moving average processing is, for example, in the count table of FIG. 7, with respect to the nth distance zone Zn, the average value of the frequencies in the distance zones Zn-1, Zn, Zn + 1 including the front and rear thereof is taken as the frequency of the distance zone Zn. This is the process of resetting.

Then, the table creating unit 12 of the distance calculator 10 creates a frequency distribution table (histogram) shown in FIG. 8 from the count table thus moving averaged. In the frequency distribution table thus created, the count frequency is large in the distance zone Z16 corresponding to the position of the object OB to be measured.

Then, the distance judgment unit 13 judges whether or not there is a frequency exceeding the judgment threshold value Q shown by the broken line in FIG. 8 in this frequency distribution table, and a flag is set in the distance zone exceeding the judgment threshold value Q (step S28). And S30).
Here, in the frequency distribution table, the count frequency is large in the distance zone Z16 corresponding to the position of the measured object OB. Therefore, when the distance zone Z16 is judged as a frequency exceeding the judgment threshold value Q by using the judgment threshold value Q, the measured object O
The distance zone Z16 corresponding to the position of B will be flagged.

Then, in step S32, the flag position, that is, the flagged distance zone is detected. At this time, if the count frequency is small with respect to the size of the determination threshold Q, the flag may not be set at all, and conversely, if the count frequency is large with respect to the size of the determination threshold Q, the count frequencies of the plurality of distance zones are May exceed the judgment threshold value Q and a plurality of flags may be set. Therefore, when there is no flag, the process proceeds from step S34 to step S38, the judgment threshold value Q is corrected to a small value, and step S26
~ S32 is repeated. On the other hand, when the number of flags is too large, the process proceeds from step S36 to step S38, the judgment threshold value Q is corrected to a large value, and steps S26 to S32 are repeated. As a result, an adjustment is made so that an appropriate number of flags are set.

Then, for the distance zone at the flagged position, a weighted average is performed based on the count frequencies of the distance zones before and after the distance zone to obtain the position of the center of gravity corresponding to the flagged distance zone (step S40), the center of gravity is calculated as the distance to the object to be measured OB (step S42), and the calculated distance is displayed on the display 8 (step S44). When a plurality of flags are set in the above flow, the distance selection unit 14 operates in response to the operation of the second operation button 6, selects a predetermined flag from the plurality of flags, and determines the center of gravity position of the flag. The distance can be displayed on the display 8.

The distance to the object to be measured OB is measured by the distance measuring device 1 as described above. When the distance is determined using the determination threshold, the distance to the object to be measured can be clearly separated if the frequency distribution table as shown in FIG. 8 is obtained. In actual measurement, as shown in FIGS. 10 to 11, for example, the contrast (contrast) between the reflected light from the object to be measured OB and the noise light may become unclear. Therefore, an error is likely to occur in the calculation of the separation distance. On the contrary, although the contrast between the reflected light and the noise light is sufficiently high, it may be disadvantageous in terms of the life and power consumption of the light receiving element. Therefore, in the distance measuring device 1 of the present embodiment, the contrast is made appropriate by changing the measurement parameter according to the measurement environment. Hereinafter, a process in which the distance measuring apparatus 1 of the present embodiment optimizes the measurement parameter will be described with reference to the flowchart of FIG. In the flows shown in FIGS. 9 and 4, the circled portions A are connected to each other to form one flow.

First, when the power source of the laser distance measuring device is turned on by operating the first operation button 5 (step S52), 1. AUTO (preliminary light emission mode (second embodiment)), 2. Fine (manual mode),
3. Rain (manual mode), 4. Choices of four operation modes at night (manual mode) are displayed (step S
54). One of the four limbs is highlighted, and by operating the second operation button 6, the highlighted options are sequentially replaced and displayed. When the choices desired by the measurer are highlighted, the measurer operates the first operation button 5 to confirm the selection (step S54). Option 2
When 4 is selected, either fine weather or rainy night is manually selected as the measurement environment, which corresponds to the manual mode of the first embodiment, and option 1
When is selected, the preliminary light emission mode of the second embodiment is set (step S56).

In FIGS. 10 to 12, there is an object to be measured OB in the distance zone Z16 with the measurement parameters set to the default values, and the environment (surroundings) at the time of measurement is fine weather, rain (daytime), and nighttime. The frequency distribution table showing the relationship between the characteristic distance zone (Z) and the frequency in each case is shown. In fine weather, as shown in FIG. 10, noise light having a large intensity constantly enters the light receiving device during the measurement time, and the object to be measured OB is measured.
It is difficult to distinguish the reflected light from. Further, at the time of rainfall, as shown in FIG. 11, light from a distance is difficult to reach because it is dispersed and attenuated by raindrops in the atmosphere. Therefore, the object to be measured OB
Is far away, it is still difficult to distinguish the reflected light from the measured object OB and the noise light. Further, at night, as shown in FIG. 12, since there are few noise light sources such as sunlight, the intensity of the noise light is low as a whole, and the reflected light from the measured object OB is projected. In this case, since the contrast (contrast) between the noise light and the reflected light is large, it is extremely easy to distinguish the reflected light from the object to be measured OB from the noise light. It is disadvantageous in terms of life and power consumption of the distance measuring device.

When the manual mode is selected, first, the environment corresponding to the environment of the main measurement is selected (step S5).
8). The controller 7 stores measurement parameters suitable for various environments. These measurement parameters are obtained by experiments and the like. Since the measurement parameters are intricately related to each other, the determination of these measurement parameters requires careful work. In general, it is preferable that the light emission intensity is high during fine weather, medium during rain, and low at night. It is preferable to change the light receiving sensitivity in the same tendency as the light emitting intensity. Further, both may be changed, or either one may be kept constant under various environments and only the other may be changed. It is preferable that the intensity threshold value is high during fine weather and moderate during rainfall, and low during nighttime, and the determination threshold value is preferably higher during fine weather and during rain than during nighttime. Here, depending on the measurer, "2. The case where the "fine" mode is selected will be described. In this case, the controller 7 reads the previously stored measurement parameters suitable for fine weather, and in the measurement parameter setting unit 20, the emission distance setting unit 21 sets the emission intensity of the measurement light and the light reception sensitivity setting unit 22 sets The light receiving sensitivity of the light receiving device, the intensity threshold setting unit 23 sets the intensity threshold TL for the reflected light intensity, and the determination threshold setting unit 24
Sets the determination thresholds for the frequency distribution to those suitable for fine weather (step S60). This set value is shown in Figure 4.
Substituting it as the initial value in step S4 of the flowchart A, the measurement process from step S6 is performed. As a result, for example, as shown in FIG. 8, a frequency distribution table in which the contrast between the noise light and the reflected light is appropriate is obtained, the determination threshold is determined from the steps of steps S32 to S38, and accurate distance measurement is performed. It can be carried out.

It should be noted that the measurement parameter setting unit 20 should similarly set the emission intensity, the light receiving sensitivity, the intensity threshold value, and the determination threshold value suitable for each situation even during rainfall (daytime) and nighttime other than fine weather. As a result, it is possible to perform accurate distance measurement as in the case of fine weather.

When the measurement parameter according to the measurement environment selected in the manual mode is thus determined (step S60), the measurement parameter is substituted into the distance measurement flowchart A (step S4), and then the conventional distance measurement is performed. Similarly, follow the steps for light emission, light reception, and frequency distribution table,
The distance to the object to be measured OB is calculated.

Next, as a second embodiment, a preliminary light emission mode will be described in which preliminary light emission is performed to specify a measurement environment, then measurement parameters are determined, and distance measurement is performed. The operation of the second embodiment is performed by turning on the power to the distance measuring device 1 (step S52, see FIG. 9) and operating the second operation button 6 and the first operation button 5 as in the first embodiment. Out of "1. The preliminary light emission mode "AUTO" is selected (steps S54 and S56), and further preliminary light emission is performed (step S70). At this time, the measurement parameters such as the emission intensity of the measurement light, the light receiving sensitivity of the light receiving element 42, the intensity threshold for the reflected light intensity, and the determination threshold for the frequency distribution are the values used in the conventional laser range finder (default values). ) Is good. Then, after the measurement light is emitted, reflected, and received, a frequency distribution table by preliminary light emission created by the table creation unit 12 in the distance calculator 10 is created.

In the controller 7, typical frequency distribution patterns in some typical measurement environments such as fine weather, rain, and night shown in FIGS. 10 to 12 and a measurement suitable for the measurement environment. The parameters are stored. The typical frequency distribution pattern is compared with the frequency distribution table obtained by preliminary light emission, the typical frequency distribution pattern that is judged to have the highest similarity / correlation is identified, and the specified typical frequency distribution is identified. A measurement parameter suitable for the measurement environment that causes the pattern is read (step S74). And
Similar to the above-described first embodiment, when the measurement parameter is substituted in step S4 (see FIG. 4) and the distance to the object to be measured OB is measured, the contrast between the noise light and the reflected light as shown in FIG. Can obtain an appropriate frequency distribution table, determine the determination threshold value from the processes of steps S32 to S38, and perform accurate distance measurement.

According to the above first and second embodiments,
Depending on the measurement environment, the intensity of the reflected light can be changed by changing the emission intensity of the measurement light emitter, the received light count of the reflected light receiver can be changed, and the intensity of the reflected light can be changed. Since the threshold can be changed to change the frequency of the frequency distribution table, or the determination threshold can be changed by changing the determination threshold for the frequency distribution when determining the distance,
Distance measuring device 1 capable of highly accurate distance measurement under various environments, low power consumption of the device, and long life of the light receiving element 1
Is obtained.

[0043]

As described above, according to the present invention,
By optimizing various measurement parameters related to distance measurement and optimizing the contrast between the measurement reflected light and the noise light under various environments, suitable measurement can be performed under various environments. Therefore, the reflected light from the object to be measured and the noise light coming randomly can be accurately separated, which enables highly accurate separation distance measurement (distance measurement).

[Brief description of drawings]

FIG. 1 is a perspective view showing an appearance of a distance measuring device according to the present invention.

FIG. 2 is a block diagram showing a configuration of the distance measuring device.

FIG. 3 is an explanatory diagram showing a case where a distance measurement is performed by looking at an object to be measured by the distance measuring device.

FIG. 4 is a flowchart showing a distance measuring method performed using the distance measuring device.

FIG. 5 is a flowchart showing a distance measuring method performed using the distance measuring device.

FIG. 6 is a graph showing a reflected light intensity with respect to an elapsed time when the reflected light is received by the distance measuring device and a table showing a state in which a flag is set for a time zone in which the reflected light intensity exceeds an intensity threshold. .

FIG. 7 is a diagram showing a count table formed by a count unit which constitutes a distance calculator of the distance measuring device.

FIG. 8 is a diagram showing a frequency distribution table formed by a table forming unit which constitutes the distance calculator.

FIG. 9 is a flowchart showing a distance measuring method performed using the distance measuring device.

FIG. 10 is a diagram showing a frequency distribution table according to a measurement example in fine weather when the measurement parameters are not adjusted in the distance measuring apparatus.

FIG. 11 is a diagram showing a frequency distribution table according to a measurement example during rain (daytime) when the measurement parameters are not adjusted in the distance measuring apparatus.

FIG. 12 is a diagram showing a frequency distribution table according to a measurement example at night when the measurement parameters are not adjusted in the distance measuring apparatus.

[Explanation of symbols] 1 distance measuring device 3 Laser emission device (measurement light emission device) 4 Reflected light receiver 7 controller 10 distance calculator 20 Measurement parameter setting section 21 Output intensity setting section 22 Light sensitivity setting section 23 Strength threshold setting unit 24 Judgment threshold setting unit

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Claims (5)

[Claims] 1. A measurement light emitter that emits pulsed measurement light toward an object to be measured, a reflected light receiver that receives reflected light reflected from the object to be measured, and the measurement light is emitted. A distance calculator that obtains a distance to the object to be measured based on an elapsed time from when the reflected light is received until the reflected light is received, and a controller that changes a measurement parameter according to a measurement environment. Ranging device. 2. The distance measuring apparatus according to claim 1, wherein a measuring person manually inputs the measurement environment. 3. The distance measuring apparatus according to claim 1, wherein preliminary light emission is performed by the measurement light emitting device, and the measurement environment is obtained by the preliminary light emission. 4. The controller stores representative measurement patterns corresponding to some representative measurement environments, and compares the measurement pattern obtained by the preliminary light emission with the representative measurement pattern to perform the measurement. The distance measuring device according to claim 3, which estimates the environment. 5. The measurement parameter is the emission intensity of the measurement light emitted from the measurement light emitter, the light receiving sensitivity of the reflected light receiver, and the measurement is performed a number of times to calculate the separation distance from the frequency distribution. At least one of an intensity threshold value for the intensity of the reflected light for one measurement and a determination threshold value for the frequency distribution when obtaining the separation distance from the frequency distribution for one measurement. The distance measuring device according to any one of 1.