JP2002328169A - Distance measuring device and method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] When a plurality of distances are calculated, these are appropriately displayed to improve usability and functions. A distance measuring apparatus includes a laser light emitting device that emits a pulsed laser light, a reflected light receiving device that receives reflected light, and a distance from an elapsed time until the reflected light is received. And a distance indicator 8 for displaying the distance. The distance calculator 10 includes a counting unit 11 that counts the number of times when the reflected light satisfies a predetermined condition, a table creation unit 12 that integrates the counts to create a frequency distribution table corresponding to the distance, and a frequency distribution. A distance determination unit 13 for determining a point where the frequency in the table exceeds a threshold value as a distance to an object to be measured, and a distance selection unit for selecting a predetermined distance when a plurality of distances are determined and displaying the distance on the distance display 8 A portion 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Such a distance measuring apparatus and method include:
The pulsed measuring light (for example, laser light) is emitted toward the object to be measured, and the elapsed time until the reflected light reflected from the object is received is measured, and the elapsed time and the propagation of the laser light are measured. 2. Description of the Related Art Conventionally, a method for obtaining a distance to an object to be measured based on a speed is known. However, when the object to be measured is irradiated with the laser pulse light and the light reflected from the object is received, not only the reflected light of the laser light but also the natural light is received, and the natural light becomes the noise light. Therefore, there is a problem that it is difficult to distinguish between reflected light from the object to be measured and noise light, and it is difficult to accurately measure distance.

By the way, when performing such distance measurement,
As long as the position of the device under test does not change, the reflected light from the device under test is always received at a fixed time after the emission of the measurement light, whereas the light receiving timing of the noise light is random. Therefore, the pulse-shaped measurement light is repeatedly emitted toward the object to be measured, and when the reflected light satisfies a predetermined condition for each emission, the distance (or elapsed time) is measured.
Is performed, and a frequency distribution table (histogram) corresponding to the distance is created by integrating the frequencies counted in the emission of all the measurement lights that are repeatedly performed.
It has been proposed that the distance at which the total number of count frequencies in the frequency distribution table becomes the largest is the distance to the measured object.

In the frequency distribution table prepared as described above, the light receiving timing of the reflected light from the measured object is always constant, and the count frequency at the distance (or elapsed time) indicating this position becomes large. However, since the light receiving timing of the noise light is random, the frequency count is performed corresponding to various different distances (or elapsed times) for each repeatedly performed frequency count, and each distance (or elapsed time) in the frequency distribution table is used. In ()), the integrated count frequency becomes small. For this reason, if a distance corresponding to a place where the frequency is large (for example, a place exceeding a predetermined threshold) in the frequency distribution table created as described above is set as the distance to the object to be measured, noise light generated at random And the distance can be measured more accurately.

[0005]

Here, when the object to be measured is large and all the laser beams emitted from the distance measuring device are irradiated on the object to be measured, the count frequency in the frequency distribution table becomes large. However, it is thought that it is sufficient to calculate the corresponding distance.However, when the object to be measured is relatively small, the reflected light returns from the object around the object to be irradiated with the laser beam around the object to be measured, or When there are a plurality of DUTs at different distances within the laser beam irradiation range of the distance measuring device and the reflected light returns from each DUT, there are multiple places where the count frequency increases in the frequency distribution table. Come. In this case, a plurality of distances will be calculated. In such a case, how to handle the plurality of distances and how to display the distances will affect the usability and functions of the distance measuring device. Has become a big problem.

The present invention has been made in view of such a problem.
When a plurality of distances are calculated as described above, an object of the present invention is to appropriately display the distances and to obtain a user-friendly or functionally superior distance measuring apparatus and method. .

[0007]

In order to achieve the above object, a distance measuring apparatus according to the present invention comprises a measuring light emitting device for emitting a pulsed measuring light toward an object to be measured; A reflected light receiver that receives the reflected light that is reflected, and a distance calculator that determines a distance to the object to be measured based on an elapsed time from when the measurement light is emitted to when the reflected light is received, A distance indicator for displaying the distance to the device under test. The distance calculator is configured to count the frequency corresponding to the distance when the reflected light satisfies a predetermined condition, and to integrate the frequency with respect to the measurement light repeatedly emitted a predetermined number of times to correspond to the distance. A table creating unit for creating a frequency distribution table, a distance determination unit that determines a location where the total number of count frequencies in the frequency distribution table exceeds a predetermined threshold as a distance to the device under test, When a plurality of distances to the object are determined, a distance selection unit is configured to select a predetermined distance from the plurality of distances and display the selected distance on a distance display.

Another distance measuring device according to the present invention, like the above distance measuring device, has a measuring light emitting device for emitting a pulse-like measuring light toward the object to be measured, and a measuring light emitting device which is reflected from the object to be measured. A reflected light receiver for receiving the reflected light, a distance calculator for calculating a distance to the measured object based on an elapsed time from when the measuring light is emitted to when the reflected light is received, and And a distance indicator for displaying the distance of the vehicle. However, in this distance measuring device, the distance calculator includes a counting unit that counts the frequency corresponding to the elapsed time when the reflected light satisfies a predetermined condition, and a frequency for the measurement light repeatedly emitted a predetermined number of times. A table creation unit that creates a frequency distribution table that accumulates and corresponds to the elapsed time, and converts the elapsed time where the total number of count frequencies in the frequency distribution table created by the table creation unit exceeds a predetermined threshold into a distance A distance judging unit for judging the distance to the object to be measured, and when a plurality of distances to the object to be measured are judged by the distance judging unit, a predetermined distance is selected from the plurality of distances and a distance display unit is selected. And a distance selection unit to be displayed.

As described above, when there are a plurality of objects to be irradiated with the measuring light, a plurality of distances are calculated because the reflected light returns from each of them. In such a case, the distance is calculated by the present invention. A predetermined distance is selected by the selection unit, and by appropriately selecting and displaying a plurality of distances, it is possible to obtain a user-friendly and functionally excellent distance measuring device.

In order to select and display an appropriate distance as described above, the distance selection unit can select the largest distance and display it on the distance display. Conversely, the distance selector may select the smallest distance and display it on the distance display. Further, the distance selection unit may select an n-th (n is a positive integer) largest distance among the plurality of distances.

The distance selection unit may be configured to set selection conditions in response to an external operation by a user. In this case, when the distance determination unit determines a plurality of distances to the object to be measured, Then, a predetermined distance is selected based on the selection conditions set in the distance selection unit and displayed on the distance display.

When a plurality of distances to the object to be measured are determined by the distance determination section, the distance selection section may select a distance in accordance with use conditions and the like and display the selected distance on the distance display. As this use condition, for example, a focus of a finder for observing the object to be measured can be used.When the focus is far, the distance selecting unit selects a large distance, and when the focus is close, the distance selecting unit is not. Choose a small distance. The weather at the time of distance measurement can be used as the use condition. When measuring the distance to the target under rainy or snowy weather, the distance selection unit selects a large distance. Note that the user may be able to switch and set the use conditions and the like.

When a plurality of distances to the object to be measured are determined by the distance determination unit, the distance selection unit may determine that there are a plurality of objects to be measured and display the plurality of distances on the distance display. . In this case, all of the plurality of distances may be displayed at once on the distance display, or the plurality of distances may be sequentially switched and displayed one by one.

On the other hand, in the distance measuring method according to the present invention, the pulse-shaped measuring light is emitted toward the object to be measured, and the distance is measured based on the elapsed time until the reflected light reflected from the object is received. First, a pulse-like measuring light is repeatedly emitted toward the object to be measured, and for each emission, the reflected light satisfies a predetermined condition when the reflected light satisfies a predetermined condition. Perform a frequency count, accumulate the frequency counted in the emission of all the measurement light performed a predetermined number of times to create a frequency distribution table corresponding to the distance, the total number of count frequencies in the frequency distribution table exceeds the threshold Is determined as the distance to the object to be measured, and this distance is displayed. In this case, when a plurality of distances to the measured object are determined, a predetermined distance is selected from these distances and displayed.

Another distance measuring method according to the present invention emits pulsed measuring light toward an object to be measured and receives reflected light reflected from the object to be measured, similarly to the above distance measuring method. The distance to the object to be measured is obtained based on the elapsed time until the measurement is performed.Here, the pulsed measurement light is repeatedly emitted toward the object to be measured, and for each emission, the reflected light has a predetermined value. When the conditions are satisfied, frequency counting is performed in accordance with the elapsed time, and a frequency distribution table is created in which the frequencies counted in the emission of all the measurement lights performed only a predetermined number of times are integrated to correspond to the elapsed time, The distance is obtained from the elapsed time when the total number of counts in the frequency distribution table exceeds the threshold, and this distance is determined and displayed as the distance to the measured object. And also in this method,
When a plurality of distances to the measured object are determined, a predetermined distance is selected from these distances and displayed.

According to the distance measuring method of the present invention having such a configuration, when there are a plurality of objects to be irradiated with the measuring light and a plurality of distances are calculated, for example, a plurality of distances are appropriately selected. In this case, it is possible to obtain a convenient and functionally superior distance measuring method.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a distance measuring apparatus 1 according to the present invention. The distance measuring device 1 includes a laser light emitter 3 and a reflected light receiver 4 in a housing 2, and emits pulsed laser light (measurement light) 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. A first operation button 5 for power on / off and distance measurement start operation and a second operation button 6 for display selection are provided on the upper surface of the housing 2. A finder window 2a (see FIG. 3) is provided on the rear surface of the housing 2. An operator who performs distance measurement using the distance measuring device 1 looks at the object to be measured through the finder window 2a. It is designed to measure the distance up to.

FIG. 2 shows a schematic internal configuration of the distance measuring device 1. In addition to the above-described configuration, a controller 7 having a distance calculator 10 and a display signal received from the controller 7 are displayed. A distance indicator 8 is provided. The distance calculator 10 includes a counting unit 11 and a table creation unit 1
2. It includes a distance determination unit 13, a threshold value selection unit 14, and a distance selection unit 15, the contents of which will be described later. The distance display 8 displays the distance inside the finder window 2a, and when the operator removes the finder window 2a, the distance is displayed in the field of view. Note that a distance indicator for performing a liquid crystal display, for example, 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 emitting device 3 includes a pulse generating circuit 31, a light emitting element (semiconductor laser) 32, and a collimating lens 33, and the reflected light receiving device 4 includes a receiving circuit 41, a light receiving element (photodiode) 42, and a condenser lens 43. Be composed.

The operation and operation when measuring the distance to the object to be measured using the distance measuring apparatus 1 configured as described above will be described below with reference to the flowcharts shown in FIGS. Note that the flows shown in FIG. 4 and FIG.

Here, as an example, as shown in FIG. 3, a case will be described in which the distance measuring device 1 is used to measure the distance to the object OB far from the window glass WG.
When measuring the distance to the object to be measured OB using the distance measuring device 1, first, as shown in FIG. 3, the operator performs the first operation while viewing the object to be measured OB through the window glass WG through the finder 2a. Operate button 5. As a result, the power is turned on, the operation signal is input from the first operation button 5 to the controller 7, and the distance measurement operation is started (step S2). In response to this, the pre-processing shown in step S4 is performed, and initialization processing such as clearing each memory is performed.

Next, a one-time measurement timer starts (step S6), and an intensity threshold TL is set (step S6).
8). Then, the timer counter is started (step S10), and the pulse generation circuit 31 is operated by the controller 7 to emit a pulsed laser beam from the light emitting element 32 (step S12). This laser light is emitted from the laser emission window 3a toward the DUT through the collimator lens 33 (laser light indicated by an arrow A in FIGS. 2 and 3).

The laser beam A emitted from the distance measuring device 1 as described above first strikes a nearby window glass WG and is partially reflected (arrow B2), and the remaining laser beam is reflected on the object OB to be measured. Irradiated. The laser beam applied to the device under test OB is reflected here as shown by an arrow B1. Then, the reflected light reflected by the window glass WG as shown by the arrow B2 and the object OB as shown by the arrow B1
A part of the reflected light reflected by (the light reflected toward the distance measuring device 1) enters the reflected light receiving window 4a (FIG. 2).
(See arrow B in FIG. 3), the light is condensed by the condensing lens 43 and irradiated on the light receiving element 42. When receiving the reflected light in this way, the light receiving element 42 sends a signal corresponding to the intensity of the reflected light to the receiving circuit 41, and the receiving circuit 41 amplifies the signal and sends it to the controller 10.

As described above, the controller 10 receives the reflected light signal as shown in FIG. 6 (A1) (step S14), and from the received signal, the distance calculator 10 uses the distance calculator 10 as follows. Measure the distance to In FIG. 6 (A1), the horizontal axis represents the elapsed time with the point of emission of the pulsed laser light from the laser beam emitter 3 as the origin, and the vertical axis represents the intensity of the reflected light received. That is, FIG. 6 (A1) shows a change in the elapsed time of the intensity of the reflected light received by the reflected light receiver 4 from when the pulsed laser light is emitted from the laser light emitter 3 in step S12.

When such reflected light is detected, a point where the reflected light intensity exceeds the intensity threshold 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 formed by being finely divided at regular time intervals (for example, 12.5 ns) based on the count of the timer counter started in step S10, as shown in FIG. 6B. For this reason, 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 exceeding the intensity threshold TL indicated by the one-dot chain line in FIG. Flags are set as shown in the first column, and the time zones Z5, Z
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 emitting device 3 to when the reflected light is received by the reflected light receiver 4 is determined by the distance using the spatial propagation speed of the laser light. The time zone can be converted as the corresponding distance zone. For convenience of explanation, both the time zone and the distance zone are Z.
1, Z2... Are shown using the same symbols,
Corresponding zones are given the same symbol numbers.
Then, as shown in FIG. 7, the flag is set in the count table formed corresponding to each of the distance zones Z1, Z2,... By the counting unit 11 constituting the distance calculator 10 of the controller 7. One frequency is added and recorded for each distance zone. In the above case, one frequency is recorded in each of the distance zones Z5, Z6, Z8, Z11, Z16, Z17, and Z18.

In this embodiment, the glass window W in FIG.
G is in the distance zone Z5, and the measured object OB is in the vicinity of the distance zone Z16. Therefore, FIG.
It is considered that peaks P11 and P12 in (A1) are reflected light from the glass window WG, peaks P15, P16 and P17 are reflected light from the target OB, and other peaks P13 and P14.
Is considered to be natural light or the like detected as noise light.

In this example, the above steps S6 to S1
The flow of 8 is configured to be repeated 520 times in total, and it is determined in step S20 whether 520 measurements have been completed. At the stage where the first pulse laser irradiation is performed as described above, the process proceeds to step S22,
After waiting for the elapse of the one-time measurement timer (for example, elapse of 1 ms), the process proceeds to step S24, and the one-time measurement timer is stopped.

Then, the process proceeds to step S6, in which the first measurement timer is restarted, and the second measurement by pulsed laser irradiation is started. Thereafter, in the same manner as in the first time, the intensity threshold TL is set (step S8), the timer counter is started (step S10), the pulse laser light is emitted (step S12), and the reflected light is received (step S14). ). FIG. 6A2 shows the intensity change of the received reflected light with respect to the elapsed time after the second irradiation of the pulsed laser light. Also in this case, in the time zone including the positions of the peaks P21 to P25 exceeding the intensity threshold TL set in step S8,
In FIG. 6B, flags are set as shown in the second column, and the time zones Z5 and Z in which the flags are set are set.
6, Z10, Z14, and Z15 are recorded in step S16.

Then, as in the case of the first pulse laser beam irradiation, one frequency is added and recorded in each of the distance zones in which the flag is set in the count table shown in FIG. In this case, the distance zones Z5, Z6, Z
One frequency is added and recorded in each of 10, Z14, and Z15. However, since one frequency is recorded in distance zones Z5 and Z6 for the first time, the recording frequency of these distance zones is two.
Becomes

FIG. 7 shows the frequency of the count table when the pulse laser light is irradiated 520 times at intervals set by the one-time measurement timer (for example, 1 ms).
When the irradiation of the pulse laser beam 520 times is completed in this way, the process proceeds to step S26, and the moving average processing of the count frequency in each distance zone is performed. This moving average processing means, for example, in the count table of FIG. 7, the distance zone Zn−n including the front and rear of the nth distance zone Zn.
The average value of the frequencies at 1, Zn, and Zn + 1 is calculated using the distance zone Zn.
This is the process of resetting as the frequency of.

Then, the table creation unit 12 of the distance calculator 10 creates a frequency distribution table (histogram) shown in FIG. 8 from the count table subjected to the moving average processing as described above. In the frequency distribution table created in this way, the count frequency in the distance zone Z5 corresponding to the position of the glass window WG and the distance zone Z16 corresponding to the position of the device under test OB where the reflected light is always likely to be generated. It is getting bigger.

Then, the distance determination unit 13 determines whether or not there is a frequency exceeding the determination threshold P that changes in accordance with the distance (distance zone) in the frequency distribution table, and flags a distance zone that exceeds the determination threshold P. (Steps S28 and S30). Here, in the frequency distribution table, the glass window W
Distance zone Z5 corresponding to the position of G and the object to be measured OB
Since the count frequency is large in the distance zone Z16 corresponding to the position, if the frequency exceeding this is determined using the determination threshold value Q that is a constant value as shown by the broken line in FIG. Flags are set in both the distance zone Z5 corresponding to the position and the distance zone Z16 corresponding to the position of the device under test OB.

For this reason, as shown by the dashed line P in FIG. 8, the determination is made using the determination threshold value P which is set in accordance with the distance (set so as to become smaller as the distance becomes longer). I have. Thereby, a flag is not set in the distance zone Z5 corresponding to the position of the glass window WG, but is set only in the distance zone Z16 corresponding to the position of the measured object OB, and the distance measurement of the measured object OB is more accurate. Becomes However, in the distance measuring device or method of the present invention,
Either of the determination thresholds P and Q may be used.

Then, the process proceeds to a step S32, wherein a flag position, that is, a distance zone where the flag is set is detected. At this time, a flag may not be set at all if the count frequency is small relative to the size of the determination threshold P, and conversely, if the count frequency is large relative to the size of the determination threshold P, the count frequency of a plurality of distance zones Exceeds the determination threshold P, and a plurality of flags may be set. For this purpose, a threshold value selector 14 is provided in the distance calculator 10, and a plurality of types of threshold values are set in advance as the determination threshold value P.
For example, the determination threshold value P ′ which is translated upward from the determination threshold value P shown in FIG. 8 (a determination threshold value of a type having a large value) P ′ or the determination threshold value which is translated downwardly (a determination threshold value having a small value) P ″ Is set.

If there is no flag, the process proceeds from step S34 to step S38, where a threshold value P ″ of a type having a small value is selected as the threshold value P, and steps S26 to S32 are repeated.
On the other hand, if the number of flags is too large, step S36
Then, the process proceeds to step S38 to select a type of determination threshold value P 'having a large value, and repeat steps S26 to S32. Thus, an adjustment is made so that an appropriate number of flags are set.

Then, a weighted average is performed on the distance zone at the position where the flag is set based on the count frequency of the distance zone before and after the distance zone to obtain the position of the center of gravity corresponding to the distance zone where the flag is set (step). S40), the position of the center of gravity is calculated as the distance to the object OB (step S42), and the calculated distance is displayed on the distance display 8 (step S44).

In the above description, an example in which the measured object OB is modeled as one simple model has been described.
When the object to be measured is viewed through the finder 2a using
An object is present around the object to be measured, and the laser light emitted from the laser light emitting device 3 irradiates not only the object to be measured but also surrounding objects, and the reflected light receiver 4
Also receives the reflected light from these. For this reason, in the frequency distribution table shown in FIG. 8, the count frequency increases in a plurality of distance zones, and a plurality of distance zones exceeding the determination threshold appear. When the object to be measured is viewed through the finder 2a, a plurality of adjacent objects to be measured may be simultaneously viewed and the distance between the plurality of objects to be measured may be measured. , A plurality of distance zones exceeding the determination threshold appear.

In such a case, in the present invention, the process proceeds to step S40 with flags set for a plurality of distance zones, and the center of gravity of each flag is calculated to obtain a plurality of distances. Then, a predetermined distance is selected from the plurality of distances by the distance selection unit 14 and displayed by the distance display 8.

The selections made by the distance selecting unit 14 include, for example, selecting the largest distance and displaying it on the distance display 8 or selecting the smallest distance and displaying it on the distance display 8. , N-th (where n is a positive integer) the largest distance is selected and displayed on the distance display 8. Which of these selection methods to use depends on
Although it may be programmed in advance, the second operation button 6
The user may be able to select and set which method is to be used by performing the above operation.

The conditions for selecting the distance in this manner include, for example, the type of the object for which the distance is to be measured, the weather conditions for performing the distance measurement, and other use conditions. The switching setting may be made by operating the button 6. In this case, the distance selection unit 14 selects a predetermined distance based on the selection condition set by the user operating the second operation button 6 and displays the selected distance on the distance display 8.

When the distance selection unit 14 selects a distance according to the use conditions and displays the distance on the distance display 8, the use conditions include, for example, the focal position of the finder 2a for visually observing the object to be measured (for example, Focus ring position). In this case, when the focus of the viewfinder 2a is far, the distance selecting unit 14 selects a large distance, and when the focus is close, the distance selecting unit 1 is selected.
4 selects a small distance and causes the distance indicator 8 to display it. The weather at the time of distance measurement can also be used as the use condition. For example, when measuring the distance to a target under rainy or snowy weather, reflected light from raindrops or snowflakes is mixed in, but reflected light from nearby raindrops or snowflakes greatly affects the distance selection unit 14. Chooses a large distance. In addition, the user sets the use conditions and the like by the second operation button 6.
May be arbitrarily set.

When the distance judging section 14 judges a plurality of distances to the object to be measured, the distance selecting section 14 judges that there are a plurality of objects to be measured, and causes the distance display 8 to display these plural distances. You may do it. In this case, all of the plurality of distances may be displayed on the distance display 8 at once, or the plurality of distances may be sequentially switched and displayed one by one. In this case, the switching of the display mode and the switching and displaying of a plurality of distances in order may be performed by operating the second operation button 6.

The object to be measured O by the distance measuring device 1 described above
In the distance measurement to B, the count table shown in FIG. 7 is formed by converting a time zone into a distance zone.
The count table may be created using the time zone as it is. In this case, in the frequency distribution table of FIG. 8 as well, the time axis can be calculated from the elapsed time of the flagged position using the time zone on the horizontal axis.
In FIGS. 6A1 and 6A2, the intensity threshold TL
Is a constant value, but this may be used as an intensity threshold value that changes according to the elapsed time. More specifically, an intensity threshold value that decreases as the elapsed time increases may be used.

[0044]

As described above, according to the present invention,
The pulse-shaped measurement light is repeatedly emitted toward the object to be measured, and a frequency distribution table corresponding to the distance or the elapsed time is created by integrating the frequencies counted in the emission of all the measurement lights, and in the frequency distribution table. Where the total number of counts exceeds the threshold is determined as the distance to the measured object, at this time, when a plurality of distances to the measured object is determined, among these plurality of distances It is configured such that a predetermined distance is selected and displayed. For this reason, when there are a plurality of targets to be irradiated with the measurement light and the reflected light returns from each, a plurality of distances are calculated, or when a distance between objects around the measured object is calculated. By appropriately selecting and displaying a predetermined distance by the distance selection unit, it is possible to obtain a user-friendly and functionally superior distance measuring device.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the appearance of a distance measuring apparatus 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 is measured by looking at an object to be measured through a window glass 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 by using the distance measuring device.

FIG. 6 is a graph showing a reflected light intensity with respect to an elapsed time when 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 constituting a distance calculator of the distance measuring device.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Distance measuring device 3 Laser beam emitting device 4 Reflected light receiver 10 Distance calculator 11 Counting unit 12 Table forming unit 13 Distance determining unit 14 Threshold selecting unit 15 Distance selecting unit

Claims (15)

[Claims] 1. A measuring light emitting device for emitting a pulsed measuring light toward an object to be measured, a reflected light receiving device for receiving reflected light reflected from the object to be measured, and an emitting device for emitting the measuring light. A distance calculator that obtains a distance to the object based on an elapsed time from when the reflected light is received until the reflected light is received, and a distance indicator that displays a distance to the object to be measured, A distance calculator configured to count a frequency corresponding to the distance when the reflected light satisfies a predetermined condition; and a distance unit that accumulates the frequency with respect to the measurement light repeatedly emitted a predetermined number of times and corresponds to the distance. A table creation unit for creating a frequency distribution table, a distance determination unit that determines a location where the total number of count frequencies in the frequency distribution table exceeds a predetermined threshold as a distance to the device under test, and the distance determination unit In the above When the distance to the measurement object has a plurality of determination, the distance measuring apparatus characterized by having a distance selection unit that selects a predetermined distance to be displayed on the distance display among the plurality of distances. 2. A measuring light emitting device for emitting a pulsed measuring light toward an object to be measured, a reflected light receiving device for receiving reflected light reflected from the object to be measured, and an emitting device for emitting the measuring light. A distance calculator that obtains a distance to the object based on an elapsed time from when the reflected light is received until the reflected light is received, and a distance indicator that displays a distance to the object to be measured, The distance calculator includes a counting unit that counts a frequency corresponding to an elapsed time when the reflected light satisfies a predetermined condition, and an elapsed time obtained by integrating the frequency with respect to the measurement light repeatedly emitted a predetermined number of times. A table creation unit that creates a frequency distribution table corresponding to the above, and the elapsed time at which the total number of count frequencies in the frequency distribution table exceeds a predetermined threshold is converted into a distance and determined as the distance to the object to be measured. Judgment distance And a distance selection unit that, when a plurality of distances to the measured object are determined in the distance determination unit, selects a predetermined distance from among the plurality of distances and displays the selected distance on the distance display. Characteristic ranging device. 3. The method according to claim 2, wherein when the plurality of distances to the object to be measured are determined by the distance determination unit, the distance selection unit selects the largest distance and displays the largest distance on the distance display. Item 3. The distance measuring device according to Item 1 or 2. 4. When a plurality of distances to the object to be measured are determined by the distance determination unit, the distance selection unit selects the smallest distance and displays the smallest distance on the distance display. Item 3. The distance measuring device according to Item 1 or 2. 5. When the plurality of distances to the object to be measured are determined by the distance determination unit, the distance selection unit is the n-th (n is a positive integer) largest of the plurality of distances. The distance measuring apparatus according to claim 1, wherein a distance is selected and displayed on the distance display. 6. The distance selection unit is configured to set selection conditions in response to an external operation by a user, and when the distance determination unit determines a plurality of distances to the device under test, The distance measuring apparatus according to claim 1, wherein a predetermined distance is selected based on the selection condition set by a distance selection unit and is displayed on the distance display. 7. When the plurality of distances to the object to be measured are determined by the distance determination unit, the distance selection unit selects a distance according to a use condition or the like and causes the distance display unit to display the selected distance. The distance measuring device according to claim 1 or 2, wherein 8. A focus of a finder for visually observing the object to be measured is used as the use condition. When the focus is far, the distance selecting unit selects a large distance, and when the focus is close, the distance is selected. The distance measuring apparatus according to claim 7, wherein the selection unit selects a small distance. 9. The weather condition at the time of distance measurement is used as the use condition, and when measuring the distance to the target under rainy or snowy weather, the distance selection unit selects a large distance. The distance measuring apparatus according to claim 7. 10. The distance measuring apparatus according to claim 7, wherein a user can switch and set the use condition and the like. 11. When a plurality of distances to the object to be measured are determined by the distance determination unit, the distance selection unit determines that there are a plurality of the objects to be measured and displays the plurality of distances on the distance display. The distance measuring apparatus according to claim 1, wherein the distance is displayed. 12. The distance measuring apparatus according to claim 11, wherein the distance display displays all of the plurality of distances at once. 13. The distance measuring apparatus according to claim 11, wherein the plurality of distances are sequentially switched and displayed one by one on the distance display. 14. A distance to the object to be measured is determined based on an elapsed time until a pulsed measuring light is emitted toward the object to be measured and reflected light reflected from the object to be received is received. In the distance measuring method, the pulse-shaped measurement light is repeatedly emitted toward the object to be measured, and for each emission, when the reflected light satisfies a predetermined condition, a frequency count is performed in accordance with the distance, A frequency distribution table corresponding to the distance is created by integrating the frequencies counted in the emission of all the measurement lights performed by the number of times, and a case where the total number of count frequencies in the frequency distribution table exceeds a predetermined threshold value Is determined as the distance to the object to be measured, and the distance to the object to be measured thus determined is displayed. When a plurality of distances to the object to be measured are determined, the plurality of distances are determined. A distance measuring method, wherein a predetermined distance is selected and displayed. 15. A distance to the object to be measured is determined based on an elapsed time until a pulsed measurement light is emitted toward the object to be measured and reflected light reflected from the object to be received is received. In the distance measurement method, the pulse-shaped measurement light is repeatedly emitted toward the object to be measured, and for each emission, when the reflected light satisfies a predetermined condition, a frequency count is performed in accordance with an elapsed time, A frequency distribution table corresponding to the elapsed time is created by integrating the frequencies counted in all of the measurement light emission performed a predetermined number of times, and the total number of count frequencies in the frequency distribution table exceeds a predetermined threshold. A distance is obtained from the elapsed time, and the distance is determined as the distance to the object to be measured. The distance to the object to be measured thus determined is displayed. When a plurality of distances are determined, a predetermined distance is selected from the plurality of distances and displayed.