JP7388064B2 - Distance measuring device and method - Google Patents

Description

The present invention relates to a distance measuring device and a distance measuring method.

A distance measuring method is known in which a laser beam is irradiated toward an imaging region, reflected light from an object present in the imaging region is received, and the distance to the object is calculated from the time difference between the emission and reception of the light. Such a distance measuring method is already known as the TOF (time of flight) method. A distance measuring device that measures distance using the TOF method is sometimes referred to as a TOF camera or a distance measuring camera. Further, although Patent Document 1 describes it as an imaging device, the imaging device described in Patent Document 1 is an example of a TOF camera.

BACKGROUND ART In a distance measuring device (TOF camera) that measures distance using the TOF method, the level (amount of light received) of reflected light from a subject is important. If the light reception level is low, the sensor output signal will be buried in noise, and if the light reception level is too high, the sensor output signal will be saturated, making it impossible to obtain an accurate distance measurement value. The invention described in Patent Document 1 attempts to obtain accurate distance measurement values by setting a photometry area by a photometry section and controlling the amount of illumination light by the illumination section so that the amount of photometry in the photometry area becomes a normal value. It is.

The imaging device (TOF camera) described in Patent Document 1 performs exposure control based on the amount of photometry of a distance measurement target area. That is, the exposure amount is measured by the photometry section, and if the photometry value is above a normal value, the amount of illumination light from the illumination section is decreased, and when the photometry value is below the normal value, the amount of illumination light from the illumination section is increased. However, in the imaging device (TOF camera) described in Patent Document 1, the amount of reflected light that is reflected by the object and reaches the imaging device (TOF camera) is determined by It is not taken into consideration that the distance varies depending on the distance from the imaging device (TOF camera) to the subject. Therefore, there is room for improvement in terms of expanding the measurable range.

The present invention has been made to solve the problems of the prior art as described above, and an object of the present invention is to provide a distance measuring device and a distance measuring method that can expand the measurable range.

The imaging device according to the present invention includes:
A light source formed by two-dimensionally arranging a plurality of light emitting regions;
an optical element that guides the emitted light emitted from the light source to a ranging area;
a light receiving unit that receives reflected light from which the emitted light is reflected by a distance measurement target existing in the distance measurement area;
A distance measuring device comprising:
The light receiving section is divided into a plurality of light receiving areas,
a region-specific light amount control unit that controls the amount of light emitted by each light emitting region of the light source corresponding to the plurality of light receiving regions;
an area light amount measurement unit that measures the amount of light received for each of the light receiving areas;
a distance measurement unit that measures the distance to the distance measurement target for each of the light reception areas by measuring the time from the light emission of the light source to the reception of light by the light reception unit for each of the light reception areas;
has
The region-based light amount control section performs preliminary light emission by simultaneously causing each light emitting point of the light source to emit light with the same amount of light, and performs main light emission based on the amount of light received for each light receiving area measured by the area light amount measurement section by the preliminary light emission. Controls the amount of light emitted by
The most important feature of the distance measuring section is that it measures the distance to the distance measurement target for each of the light receiving areas by the main light emission.

The imaging method according to the present invention includes:
A light source formed by two-dimensionally arranging a plurality of light emitting regions;
an optical element that guides the emitted light emitted from the light source to a ranging area;
a light receiving unit that receives reflected light in which the emitted light is reflected by a distance measurement target existing in the distance measurement area;
A distance measuring method using a distance measuring device equipped with
The light receiving section is divided into a plurality of light receiving areas,
a region-based light amount control step of controlling the amount of light emitted from each light emitting region of the light source corresponding to the plurality of light receiving regions for each light emitting region;
an area light amount measurement step of measuring the amount of light received for each of the light receiving areas;
a distance measuring step of measuring the distance to the measurement target for each of the light receiving areas by measuring the time from the light emission of the light source to the reception of light by the light receiving unit for each of the light receiving areas;
has
In the region-specific light amount control step, each light emitting point of the light source simultaneously emits light with the same amount of light to perform preliminary light emission, and the main light emission is performed based on the amount of light received for each region measured in the region light amount measurement step by the preliminary light emission. control the amount,
The most important feature of the distance measuring step is to measure the distance to the distance measurement target for each of the light receiving areas by the main light emission.

According to the present invention, it is possible to expand the measurable range for both long-distance objects and short-distance objects.

1 is a schematic diagram schematically showing an optical system and a control system of an embodiment of a distance measuring device and a distance measuring method according to the present invention. FIG. 2 is a front view and a vertical and horizontal illuminance distribution diagram showing an example of a laser light source in which a plurality of light emitting regions are arranged in a two-dimensional array. It is a graph showing a range in which distance measurement is possible and a range in which distance measurement is not possible when the amount of light emitted from a laser light source is kept constant. It is a graph showing an example of output control of a laser light source with respect to a TOF sensor output. FIG. 6 is a diagram showing the distribution of TOF sensor output in each imaging region when the laser light source is pre-emit. FIG. 7 is a diagram showing a light emission amount distribution during main light emission of the laser light source corresponding to a distribution of TOF sensor output in each imaging region when the laser light source causes preliminary light emission. 3 is a flowchart showing operations during normal photographing according to the present invention. 3 is a flowchart illustrating an operation when photographing multiple times according to the present invention. 7 is a timing chart illustrating the reason for deterioration of distance measurement accuracy and failure of distance measurement when the object distance is too close and when the object distance is too far.

Embodiments of a distance measuring device and a distance measuring method according to the present invention will be described below with reference to the drawings.

[Example 1]
FIG. 1 shows a TOF camera 10 which is an embodiment of a distance measuring device according to the present invention. In FIG. 1, the TOF camera 10 includes a light projection system 20 that emits a rectangular wave or sine wave laser beam whose frequency is modulated on the order of megahertz [MHz], and a light projection system 20 that receives light that is reflected when the projected light hits an object, that is, a subject. The light receiving system 30 is equipped with a light receiving system 30 for

The light projection system 20 has a vertical cavity surface emitting laser (hereinafter referred to as "VCSEL") 21 as a light source. The VCSEL 21 in this embodiment has a plurality of light emitting regions arranged two-dimensionally. The light emitting operation of each light emitting region of the VCSEL 21 is controlled by the light emitting control section 50. The light projection system 20 also includes a lens 22 that spreads the light emitted from each light emitting point of the VCSEL 21 to a necessary angle of view and projects the light.

The TOF camera 10 has a determination section 40. The determination unit 40 controls the light emission timing, light emission amount, etc. of each light emission region of the VCSEL 21 by controlling the light emission control unit 50.

The light-receiving system 30 includes a light-receiving lens 31 that collects light that has hit a subject and is reflected, and a light-receiving sensor 32 that receives the light collected by the light-receiving lens 31 and converts it photoelectrically. In this embodiment, a TOF sensor is used as the light receiving sensor 32. In the light-receiving sensor 32, the light-receiving area by the sensor element is arranged in the same two-dimensional arrangement as the arrangement of each light-emitting area of the VCSEL 21, and a detection signal is outputted from each sensor element by dividing it into each determined area.

As explained above, the TOF camera 10 uses a laser light source in which a plurality of light emitting regions are arranged two-dimensionally, and meshes the imaging surface of the image sensor into a plurality of regions having the same number and the same arrangement as the plurality of light emitting regions. By dividing the imaging area into a plurality of areas, the distance measurement is performed for each area.

A detection signal from the light receiving sensor 32 is input to a photometry/control section 60 . The photometry/control unit 60 functions as an area light amount measurement unit that statistically processes sensor output values from each detection area of the light receiving sensor 32 made of a TOF sensor and measures the level of received light (amount of received light) for each imaging area. The photometry/control unit 60 also controls the light receiving time, light receiving sensitivity, timing, etc. of the light receiving sensor 32 in synchronization with light projection control from each light emitting area of the VCSEL 21. The function of the area light amount measurement unit is to measure the light reception level (light reception amount) for each imaging area even when the VCSEL 21 is pre-emitting laser light, and based on the reception light amount for each imaging area, the light emission amount during main emission is determined. It is controlled by a region-specific light amount control unit 41, which will be described later.

The determining unit 40 includes a region-by-area light amount control unit 41 that determines the light emission amount for each light-emitting region of the VCSEL 21 and the light-receiving sensitivity of the light-receiving sensor 32 at the time of photographing based on the sensor output statistical value for each light-receiving region of the light-receiving sensor 32. The determining unit 40 also operates a distance measuring unit 42 that measures the distance to the distance measurement target for each imaging area by measuring the time from the emission of laser light by the VCSEL 21 to the reception of the laser beam by the light receiving sensor 32 for each imaging area. have

The distance measurement operation by the TOF camera 10 is equivalent to the operation of a general phase detection type TOF camera, and is a well-known technique. For example, a technology similar to that of the TOF camera described in Japanese Patent Application Publication No. 2018-077143 can be used. Therefore, detailed explanation of the distance measurement operation by the TOF camera 10 will be omitted.

Next, the element arrangement of the two-dimensional array of the VCSEL 21 used as a light source shown in FIG. 2 will be explained. FIG. 2 is a diagram schematically showing the light-emitting surface of the VCSEL 21, with black circles indicating light-emitting regions, and 64 light-emitting regions in total, 8 each in the vertical and horizontal directions, are arranged. Further, within each light emitting region, a plurality of VCSEL elements are arranged at equal intervals.

In FIG. 2, horizontal and vertical illuminance distribution curves are shown along the upper and left edges of the VCSEL element, respectively. Among these illuminance distribution curves, the dotted line shows the illuminance distribution curve of each element, and the solid line shows the illuminance distribution curve when all the elements emit light at the same time. As can be seen from these illuminance distribution curves, when all the elements emit light simultaneously, substantially uniform surface light emission occurs. In other words, the arrangement intervals of the elements are determined so as to provide uniform surface emission. Although it varies depending on the specifications of the VCSEL element, the scale is approximately 50 μm on one side.

FIG. 3 shows the detection signal output from the light receiving sensor 32 when the entire area of the VCSEL 21 emits light with the same amount of light, and the light receiving sensor 32 receives the reflected light from the subject. Shows the relationship between the outputs. In FIG. 3, the horizontal axis represents the subject distance, and the vertical axis represents the output of the light receiving sensor 32 in levels from 0 to 255. Naturally, the subject is within the field of view of the light receiving sensor 32.

Here, if the horizontal direction of the light receiving surface of the light receiving sensor 32 is defined as the X direction, the vertical direction as the Y direction, and the direction perpendicular to the light receiving surface and away from the light receiving surface as the Z direction, the light receiving surface becomes the XY plane. When looking at the area to be measured from the light receiving sensor 32 (distance measurement area), unless the object existing in the distance measurement area is a plane parallel to the XY plane, the distance to the object existing in each divided area on the XY plane, i.e. The distance to the subject differs for each divided area.

Then, when the amount of distance measuring light by the TOF method is made uniform and is emitted toward the imaging area, the level of reflected light becomes high in an area where a nearby object exists, and the output level of the light receiving sensor 32 becomes saturated. Further, in a region where a distant object exists, the level of reflected light is low, and the output signal of the light receiving sensor 32 is buried in noise. In other words, if the subject is too close or too far away, distance measurement becomes impossible or the distance measurement accuracy deteriorates, and as a result, the distance range of the subject that can be measured is limited.

I will explain in detail. When the VCSEL 21 emits light with the same amount of light for all pixels arranged in an array, as shown in FIG. 3, the reflected light from a distant object is attenuated and the output of the light receiving sensor 32 becomes small. In the example shown in FIG. 3, when the subject distance exceeds 7 m, the relationship between the sensor output and the subject distance becomes non-linear and the distance measurement accuracy deteriorates, so the output of the light receiving sensor 32 is invalidated. For a close-distance object, the attenuation of reflected light is small, so the output of the light receiving sensor 32 becomes large.

FIG. 8 explains the reason why the accuracy of distance measurement by the light receiving sensor 32 deteriorates or becomes impossible to measure distance for a close or long distance object. FIG. 8(a) shows the amount of light emitted from the VCSEL 21 and the time. The emission waveform is a rectangular waveform.

FIG. 8(b) shows the output waveform of the light receiving sensor 32 when the subject distance is an intermediate distance (1 to 7 m). The received light waveform is not rectangular but a sinusoidal waveform with a slight delay. In order to determine the point at which the phase difference Δt between emitted light and received light is measured, an output judgment threshold is set in the light receiving sensor 32, and the time required to reach this level is determined. Measure and convert the phase difference into distance. Accurate distance measurement is possible for objects at intermediate distances.

FIG. 8(c) shows the output waveform of the light receiving sensor 32 when the subject distance is short (within 1 m). When the subject is close, the output of the light receiving sensor 32 is greatly saturated, and the rise of the waveform becomes steep. For this reason, an error occurs in the time when the output of the light receiving sensor 32 reaches the determination threshold (50% in this example) with respect to the originally assumed sine waveform. This error component is indicated by E in FIG. 2(b). The effect of this error E becomes larger as the phase difference Δt becomes smaller at a shorter distance, so when the output of the light receiving sensor 32 is saturated at a shorter distance, the distance measurement error becomes larger. Therefore, when the output of the light receiving sensor 32 is saturated, distance measurement calculation is not performed.

FIG. 8(d) shows the output of the light receiving sensor 32 when the subject is far away (more than 7 meters). The farther the subject is, the lower the amount of light received by the light receiving sensor 32 is. Therefore, the output of the light receiving sensor 32 does not exceed the determination threshold necessary for phase difference measurement, making it impossible to measure the phase difference Δt. In this case as well, distance measurement calculations are not performed.

As is clear from FIG. 8, the distance to a subject that can be measured by simultaneously emitting the same amount of light once by all elements of the VCSEL 21 is limited to a certain range.

FIG. 4 shows the control of the amount of light emitted from the VCSEL 21 according to the output of the light receiving sensor 32. The horizontal axis in FIG. 4 is the output of the light receiving sensor 32, with the maximum level represented by 255 and the minimum level represented by 0. The vertical axis represents the amount of light emitted by the VCSEL 21, which is 3W at maximum.

As shown in FIG. 4, when all elements of the VCSEL 21 simultaneously emit light with the same amount of light (first light emission, preliminary light emission), the light emission amount of the VCSEL 21 during the second light emission, that is, the main light emission, is determined according to the output of the light receiving sensor 32. Control. If the distance to the subject is far and the output of the light receiving sensor 32 is so small in the preliminary light emission that distance measurement cannot be performed, the amount of light emitted by the VCSEL 21 in the main light emission is increased. If the distance to the subject is short and the output of the light receiving sensor 32 is saturated during preliminary light emission and distance measurement cannot be performed, the amount of light emitted by the VCSEL 21 during the main light emission is reduced. Such control of the light emission amount in the main light emission is performed by the area-based light amount control section 41 controlling the light emission control section 50.

5(a) and 5(b) explain the control of the amount of light emitted by the VCSEL 21 according to the photometric value of each light receiving area of the light receiving sensor 32. FIG. 5A shows an example of the output distribution of the light receiving sensor 32 in each area during preliminary light emission when the light receiving area of the light receiving sensor 32 is divided into 8×8 areas by changing the filling pattern. Specifically, according to the output of the light-receiving sensor 32, areas with high output are expressed by a filled pattern with a low density, and areas with a low output are expressed with a filled pattern with a high density. In other words, an area expressed with a light fill pattern indicates that the distance to the subject in this area is short, and an area expressed with a dark fill pattern indicates that the distance to the subject in this area is short. It shows that the distance is far. The area where the subject is substantially at infinity is represented by a filled pattern with the highest density, and the area where the subject is closest, in other words, the area where the output of the light receiving sensor 32 is maximum (light receiving The area (area where the output of the sensor 32 is saturated) is shown in white without using a fill pattern. In addition, in FIG. 5(a), in order to simplify the explanation, five types of fill patterns including white are used, but this shows that the actual output of the light receiving sensor 32 is in five levels. It's not a thing.

FIG. 5(b) shows how to change the filling pattern of the light emission amount for each area set for the VCSEL 21 when the output distribution of the light receiving sensor 32 becomes like the example shown in FIG. 5(a) during preliminary light emission. It is expressed as This indicates that the lighter the density of the filled pattern, the greater the amount of light emitted. Corresponding to FIG. 5(a), the amount of light emitted by the VCSEL 21 is small in areas where the subject is considered to be close, and the amount of light emitted by the VCSEL 21 is increased in areas where the subject is considered to be far away. to control. Note that, similar to FIG. 5(a), in FIG. 5(b), in order to simplify the explanation, five types of fill patterns are used, including white, but the actual light emission amount of the VCSEL 21 is in five levels. It does not indicate that it is.

FIG. 6 shows a processing flow for normal photography in which the light receiving sensor 32 is set to standard sensitivity. In STEP 1, preliminary light emission is performed before photographing. At this time, the amount of light emitted from the VCSEL 21 is set to be common to all pixels, and set so that the amount of light emitted from the VCSEL 21 is uniform throughout the area.

In STEP 2, the light receiving sensor 32 receives and detects the reflected light of the preliminary light emission. The light receiving area of the light receiving sensor 32 is divided as described above, and the statistical value of each area is calculated from the sensor output value in each area.

In STEP 3, the amount of light emitted in each area of the VCSEL 21 at the time of actual photographing is set from the statistical value of each light receiving area calculated in STEP 2. The amount of light emitted by the VCSEL 21 is as described in FIGS. 5(a) and 5(b).

In STEP 4, the main light emission is performed by causing the VCSEL 21 to emit light with the light emission amount set in STEP 3. In STEP 5, data of the light receiving sensor 32 is acquired in accordance with the light emission timing.

In STEP 6, distance measurement processing is executed from the data of the light receiving sensor 32 acquired in STEP 5, and distance information of the subject within the angle of view is calculated. As described above, by setting an appropriate amount of light emission for each light emitting area of the VCSEL 21, it is possible to expand the range of subject distances that can be measured.

[Example 2]
FIG. 7 shows a case where the sensitivity of the light-receiving sensor 32 is reset, and shows an example of a processing flow for photographing with high sensitivity. STEPs 1 to 5 in FIG. 7 are the same as STEPs 1 to 5 in the processing flow of FIG. 6, and are executed up to the acquisition of photographic data. In STEP 6, the light receiving sensor 32 detects the reflected light during the main emission, calculates the statistical value of the sensor output for each light receiving area, and detects an area where the sensor output is too small to measure the distance, that is, an area where sensitivity needs to be increased.

In STEP7, the light-receiving sensitivity of the light-receiving sensor 32 is increased only for the sensitivity-up required area detected in STEP6. In STEP 8, the amount of light emission is set for each light emitting region of the VCSEL 21, and in accordance with this setting, each light emitting region of the VCSEL 21 is caused to emit light.

In STEP 10, the light receiving sensor 32 measures light for each light receiving area. In STEP 11, as a result of the photometry in STEP 10, it is confirmed whether or not there is a region requiring increased sensitivity. If a region requiring increased sensitivity remains, the process returns to STEP 7 to increase the sensitivity of that region and perform photometry again. If there is no area requiring increased sensitivity, the process proceeds to STEP 12, where photographing processing is performed and data detected by the light receiving sensor 32 is stored. In STEP 11, if a region requiring increased sensitivity remains, the flow from STEP 7 is repeated, and the number of shots is set to N times as the upper limit, and the shooting process in STEP 12 is performed.

In STEP 13, distance measurement processing is executed from the data of the light receiving sensor 32 acquired in STEP 12, and distance information of the subject within the viewing angle is calculated.

By processing as described above, the appropriate amount of light emission for each light emitting area of the VCSEL 21 and the appropriate sensitivity for each light receiving area of the light receiving sensor 32 are achieved, making the range of subject distance that can be measured even further than the range shown in Figure 6. It becomes possible to expand.

In the embodiments described above, a VCSEL in which a plurality of light emitting regions are arranged two-dimensionally is used as a laser light source in which a plurality of light-emitting regions are arranged two-dimensionally. However, the light source is not limited to a VCSEL as long as it is a light source formed by two-dimensionally arranging a plurality of light emitting regions.

20 Light projecting system 22 Optical element 30 Light receiving system 32 Light receiving sensor 41 Area-specific light amount control section 42 Distance measuring section 50 Light emission control section

Patent Application No. 2012-198337

Claims (14)

a light projection system including a light source having a plurality of light emitting regions and projecting light onto a distance measurement region ;
a light receiving system that includes a light receiving section having a plurality of light receiving areas, receives reflected light emitted from the light source and reflected by a distance measurement target existing in the distance measurement area , and outputs a detection signal;
a region- specific light amount control unit that controls the amount of light emitted from each light emitting region of the light source corresponding to the plurality of light receiving regions for each light emitting region;
an area light amount measurement unit that measures the amount of light received for each of the light receiving areas;
Equipped with
The area - specific light amount control unit causes the light projection system to perform first light projection,
The light receiving system outputs a first detection signal by the first light projection,
The area-specific light amount control unit controls the amount of light emitted from each of the light emitting areas in the second light projection based on the amount of light received for each light receiving area measured by the area light amount measurement unit based on the first detection signal. causing the light projection system to perform a second light projection ,
The distance measuring device is characterized in that the light receiving system outputs a second detection signal based on the second light projection . Based on the amount of light received in each of the light receiving areas measured by the first light emitting, the light emission of each light emitting area of the light source is such that the area where the amount of light received is larger, the smaller the amount of light emitted by the second light emitting is. The distance measuring device according to claim 1, wherein the distance measuring device controls the amount . A statistical value for each light-receiving area is calculated from an output value for each light-receiving area in the first light emission, and based on the statistical value, a light emission amount of each light-emitting area of the light source in the second light emission is controlled. The distance measuring device according to claim 1. The distance measuring device according to claim 1 , wherein the illuminance distribution of the light emitted from the light source in the first light projection in the distance measuring area is uniform . 2. The distance measuring device according to claim 1 , wherein the plurality of light-receiving areas are divided into a light-receiving surface of an image sensor so as to have the same number and the same arrangement as the plurality of light-emitting areas. A light source formed by two-dimensionally arranging a plurality of light emitting regions;
an optical element that guides the emitted light emitted from the light source to a ranging area;
a light receiving unit that receives reflected light from which the emitted light is reflected by a distance measurement target existing in the distance measurement area;
A distance measuring device comprising:
The light receiving section is divided into a plurality of light receiving areas,
a region-specific light amount control unit that controls the amount of light emitted from each light emitting region of the light source corresponding to the plurality of light receiving regions for each light emitting region;
an area light amount measurement unit that measures the amount of light received for each of the light receiving areas;
a distance measurement unit that measures the distance to the distance measurement target for each of the light reception areas by measuring the time from the light emission of the light source to the reception of light by the light reception unit for each of the light reception areas;
has
The region-based light amount control section performs preliminary light emission by simultaneously causing each light emitting point of the light source to emit light with the same amount of light, and performs main light emission based on the amount of light received for each light receiving area measured by the area light amount measurement section by the preliminary light emission. Controls the amount of light emitted by
The distance measuring device is characterized in that the distance measuring unit measures the distance to the distance measuring object for each of the light receiving areas by the main light emission . The area-specific light amount control unit controls each light emitting area of the light source so that the area where the amount of received light is larger is smaller in the amount of light emitted in the main emission based on the amount of light received in each of the light receiving areas measured in the preliminary light emission. 7. The distance measuring device according to claim 6, wherein the distance measuring device controls the amount of light emitted by the distance measuring device. a control unit that controls the light-receiving sensitivity of each light-receiving area of the light-receiving unit;
7. The distance measuring device according to claim 6, wherein the distance measuring section measures the distance by increasing the light receiving sensitivity of a light receiving area where the amount of light received by the area light amount measuring section is insufficient , by using the control section. a control unit that controls the light-receiving sensitivity of each light-receiving area of the light-receiving unit;
7. The distance measuring device according to claim 6, wherein the distance measuring section measures the distance by lowering the light receiving sensitivity of the light receiving area where the amount of light received measured by the area light amount measuring section is saturated. The distance measuring device according to any one of claims 6 to 9, wherein the light source is a vertical cavity surface emitting laser. The distance measuring device according to any one of claims 6 to 10, wherein the optical element is a wide-angle lens. A light source formed by two-dimensionally arranging a plurality of light emitting regions;
an optical element that guides the emitted light emitted from the light source to a ranging area;
a light receiving unit that receives reflected light from which the emitted light is reflected by a distance measurement target existing in the distance measurement area;
A distance measuring method using a distance measuring device equipped with
The light receiving section is divided into a plurality of light receiving areas,
a region-based light amount control step of controlling the amount of light emitted from each light emitting region of the light source corresponding to the plurality of light receiving regions for each light emitting region;
an area light amount measurement step of measuring the amount of light received for each of the light receiving areas;
A distance measuring step of measuring the distance to the distance measurement target for each of the light receiving areas by measuring the time from the light emission of the light source to the reception of light by the light receiving unit for each of the light receiving areas;
has
In the region-specific light amount control step, each light emitting point of the light source simultaneously emits light with the same amount of light to perform preliminary light emission, and the main light emission is performed based on the amount of light received for each region measured in the region light amount measurement step by the preliminary light emission. control the amount,
The distance measuring method is characterized in that in the distance measuring step, the distance to the distance measuring object is measured for each of the light receiving areas by the main light emission. a control unit that controls the light-receiving sensitivity of each light-receiving area of the light-receiving unit;
13. The distance measuring method according to claim 12, wherein in the distance measuring step, the control unit increases the light receiving sensitivity of the light receiving area where the amount of light received in the area light amount measuring step is insufficient. a control unit that controls the light-receiving sensitivity of each light-receiving area of the light-receiving unit;
13. The distance measuring method according to claim 12, wherein in the distance measuring step, the distance is measured by lowering the light receiving sensitivity of the light receiving area where the amount of light received measured in the area light amount measuring step is saturated.

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