JP7762088B2 - Measuring equipment - Google Patents

Description

The present invention relates to a measuring device.

Patent Document 1 describes a distance measuring device that measures the distance to a reflecting object based on the time of flight of light from when a pulse of light is emitted until the reflected light is received.

Japanese Patent Application Laid-Open No. 2021-152536

In the device described in Patent Document 1, light is scanned by rotating a mirror. However, moving parts such as those that rotate the mirror are prone to malfunction. On the other hand, if light is irradiated without using a moving part, there is the issue that the measurable range (measurement area) becomes narrower.

The present invention aims to expand the measurement area that can be irradiated with light without using moving parts.

One form of the present invention to achieve the above-mentioned object is a measurement device comprising a light source, a light projection optical system that irradiates light from the light source onto a measurement area, and a light receiving unit that receives reflected light from the measurement area , wherein the light source has a plurality of light-emitting regions arranged in a first direction, and the light projection optical system has a coupled lens that connects a first lens element whose optical axis is shifted in the first direction and a second lens element whose optical axis is shifted in the opposite direction to the first lens element, and the light from the light source is irradiated onto a first measurement area via the first lens element, and the light from the light source is irradiated onto a second measurement area including an overlapping area that overlaps with the first measurement area via the second lens element, and light is emitted from a specific light-emitting region of the plurality of light-emitting regions, and the light is irradiated onto a predetermined region of the first measurement area via the first lens element, and the light is irradiated onto a predetermined region of the second measurement area via the second lens element .

Furthermore, the problems disclosed in this application and the solutions thereto will be made clear in the detailed description and drawings.

This invention makes it possible to expand the measurement area onto which light can be irradiated without using any moving parts.

FIG. 1 is an explanatory diagram of the overall configuration of a measurement device 1. FIG. 2 is an explanatory diagram of the configuration of the irradiation unit 10. Fig. 3A is an explanatory diagram of the light source 12. Fig. 3B is an explanatory diagram of the measurement area 50. Fig. 3C is an explanatory diagram of an example in which the measurement device 1 is mounted on a vehicle. FIG. 4 is a perspective view of the coupling lens 15. As shown in FIG. 5A and 5B are explanatory diagrams of the measurement area 50. FIG. 6A and 6B are explanatory diagrams of optical conditions. FIG. 7 is an explanatory diagram of the light receiving sensor 22. FIG. 8 is a timing chart for explaining an example of a measurement method. Fig. 9A is an explanatory diagram of another example of the light receiving sensor 22. Fig. 9B is an explanatory diagram of the signal processing unit 362. Fig. 9C is an explanatory diagram of a histogram. 10A and 10B are explanatory diagrams showing the relationship between the light emitting region of the light source 12 and the measurement area 50. FIG. FIG. 11 is an explanatory diagram of the state when measuring region H, which is the overlapping area 53. FIG. 12 is an explanatory diagram of another measurement method.

The following describes embodiments of the present invention with reference to the drawings. Note that in the following description, identical or similar components may be designated by common reference numerals, and redundant explanations may be omitted.

<Overall structure>
FIG. 1 is an explanatory diagram of the overall configuration of a measurement device 1.

The measuring device 1 is a device that measures the distance to an object 90. The measuring device 1 is a device that functions as a so-called LiDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging). The measuring device 1 emits measuring light, detects the reflected light reflected from the surface of the object 90, and measures the time from emitting the measuring light to receiving the reflected light, thereby measuring the distance to the object 90 using the TOF (Time of Flight) method. The measuring device 1 has an irradiation unit 10, a light receiving unit 20, and a control unit 30.

The irradiation unit 10 irradiates measurement light toward the object 90. The irradiation unit 10 irradiates the measurement light onto a measurement area 50 (described below) at a predetermined angle of view. The irradiation unit 10 has a light source 12 and a light projection optical system 14. The light source 12 emits light. The light source 12 is configured, for example, by a vertical cavity surface emitting laser (VCSEL). The light projection optical system 14 is an optical system that irradiates the light emitted from the light source 12 onto the measurement area 50. The detailed configuration of the irradiation unit 10 will be described later.

The light receiving unit 20 receives light reflected from the object 90. The light receiving unit 20 receives light reflected from the measurement area 50. The light receiving unit 20 has a light receiving sensor 22 and a light receiving optical system 24.

The control unit 30 is responsible for controlling the measurement device 1. The control unit 30 controls the emission of light from the emission unit 10. The control unit 30 also measures the distance to the object 90 using the TOF (Time of Flight) method based on the output results of the light receiving unit 20. The control unit 30 has a calculation unit and a storage device (not shown). The calculation unit is, for example, a calculation processing device such as a CPU or GPU. Part of the calculation unit may be composed of an analog calculation circuit. The storage device is composed of a main storage device and an auxiliary storage device, and is a device that stores programs and data. The calculation unit executes programs stored in the storage device to perform various processes for measuring the distance to the object 90. Functional blocks of the various processes are shown in the figure.

The control unit 30 has a setting unit 32, a timing control unit 34, and a distance measurement unit 36. The setting unit 32 performs various settings. The timing control unit 34 controls the processing timing of each unit. For example, the timing control unit 34 controls the timing of emitting light from the light source 12. The distance measurement unit 36 measures the distance to the object 90. The distance measurement unit 36 has a signal processing unit 362, a time detection unit 364, and a distance calculation unit 366. The signal processing unit 362 processes the output signal of the light receiving sensor 22. The time detection unit 364 detects the time of flight of light (the time from when light is emitted until the reflected light arrives). The distance calculation unit 366 calculates the distance to the object 90. The processing of the control unit 30 will be described later.

<Regarding the irradiation unit 10>
2 is an explanatory diagram of the configuration of the irradiation unit 10. As already described, the irradiation unit 10 has a light source 12 and a light projection optical system 14.

In the following description, the direction along the optical axis of the light projection optical system 14 is referred to as the Z direction. Note that the object 90 to be measured by the measuring device 1 is separated from the measuring device 1 in the Z direction. The direction perpendicular to the Z direction, in which the first lens element 151 and second lens element 152 that make up the coupled lens 15 (described below) are aligned, is referred to as the Y direction. The direction perpendicular to the Z and Y directions is referred to as the X direction.

FIG. 3A is an explanatory diagram of the light source 12.
The light source 12 has a light-emitting surface parallel to the XY plane (a plane parallel to the X and Y directions). The light-emitting surface is rectangular. Light emitted from the light source 12 is irradiated onto the measurement area 50 via the light-projecting optical system 14.

The light projection optical system 14 has a coupling lens 15. FIG.
The coupled lens 15 is an optical component in which a first lens element 151 and a second lens element 152 are coupled together. The first lens element 151 and the second lens element 152 are convex lens-shaped portions (optical elements) and are arranged side by side in the Y direction. The focal length of the first lens element 151 is the same as the focal length of the second lens element 152. The first lens element 151 and the second lens element 152 each have an optical axis along the Z direction. The optical axis of the first lens element 151 is shifted in the +Y direction with respect to the optical axis of the light projection optical system 14 (projection lens 16, described later). On the other hand, the optical axis of the second lens element 152 is shifted in the −Y direction with respect to the optical axis of the light projection optical system 14. In other words, the optical axis of the second lens element 152 is shifted in the opposite direction to that of the first lens element 151.

The light projection optical system 14 also has a projection lens 16. The projection lens 16 is a lens positioned between the light source 12 and the connecting lens 15. By having the projection lens 16, the light from the light source 12 can be projected over a wide range of the measurement area 50. By having the projection lens 16, the light from the light source 12 can be projected onto the measurement area 50 in a rectangular light distribution pattern. The distance between the projection lens 16 and the light source 12 is shorter than the focal length of the projection lens 16. Although the light beams from the projection lens 16 toward the connecting lens 15 diverge, the convex first and second optical elements suppress the spread of the light irradiated from the connecting lens 15 toward the measurement area 50 (light close to collimated light is irradiated from the light projection optical system 14 onto the measurement area 50).

Figure 3B is an explanatory diagram of the measurement area 50. Figures 5A and 5B are explanatory diagrams of the measurement area 50. Figure 5A is an explanatory diagram of how light from the light source 12 is irradiated onto the first measurement area 51 via the first lens element 151. Figure 5B is an explanatory diagram of how light from the light source 12 is irradiated onto the second measurement area 52 via the second lens element 152.

The measurement area 50 is composed of a first measurement area 51 and a second measurement area 52. The first measurement area 51 is an area onto which light from the light source 12 is irradiated via the first lens element 151 (in other words, the first lens element 151 is an optical element that irradiates the first measurement area 51 with light from the light source 12). The second measurement area 52 is an area onto which light from the light source 12 is irradiated via the second lens element 152 (in other words, the second lens element 152 is an optical element that irradiates the second measurement area 52 with light from the light source 12). Because the first lens element 151 and the second lens element 152 are arranged side by side in the Y direction, the first measurement area 51 and the second measurement area 52 are arranged offset in the Y direction. This allows the measurement area 50 to be set long in the Y direction (in other words, light can be irradiated over a wide area in the Y direction).

In this embodiment, the first measurement area 51 and the second measurement area 52 overlap. In the following description, the area where the first measurement area 51 and the second measurement area 52 overlap is referred to as the "overlap area 53." By providing the overlap area 53, it is possible to prevent the formation of an area between the first measurement area 51 and the second measurement area 52 where light cannot be irradiated.

As shown in Figure 3B, when the measurement area 50 is viewed from the Z direction, the measurement area 50 has a predetermined angle of view in the X and Y directions. In this embodiment, the ratio of the length in the Y direction to the length in the X direction (the so-called aspect ratio) of the measurement area 50 is greater than that of the light source 12. In other words, in this embodiment, the measurement area 50 can be set longer in the Y direction compared to the shape of the light source 12 (in other words, light can be irradiated over a wider range in the Y direction).

As shown in FIG. 5A, the region of the light-emitting surface of light source 12 that emits light to illuminate overlap area 53 via first lens element 151 is referred to as "first region 121." Also, as shown in FIG. 5B, the region of the light-emitting surface of light source 12 that emits light to illuminate overlap area 53 via second lens element 152 is referred to as "second region 122."

In the overlapping area 53, light passing through the first lens element 151 and light passing through the second lens element 152 can be irradiated separately. When the first region 121 and the second region 122 of the light source 12 are illuminated simultaneously, the light irradiated through the first lens element 151 and the light irradiated through the second lens element 152 can be superimposed in the overlapping area 53. Therefore, the light irradiation intensity can be increased in the overlapping area 53 compared to the measurement area 50 excluding the overlapping area 53.

As shown in Figure 3B, the overlap area 53 (hatched area), where the illumination intensity is relatively high, is located in the center of the measurement area 50 in the Y direction. By collectively illuminating the light-emitting surface of the light source 12 (i.e., by simultaneously illuminating the first area 121 and the second area 122 of the light source 12), the intensity of the light irradiated onto the center of the measurement area 50 (overlap area 53) can be increased, as shown in Figure 3B.

3C is an explanatory diagram of an example in which the measurement device 1 is mounted on a vehicle. As shown in the figure, when the measurement device 1 is mounted on a vehicle, it is desirable to measure distances with a wide field of view in relatively close proximity. In contrast, in this embodiment, as shown in FIG. 3B, the aspect ratio of the measurement area 50 can be widened, which is advantageous for measuring distances with a wide field of view.
On the other hand, when the measurement device 1 is mounted on a vehicle, the area where long-distance measurement is required can be a relatively small range, but it is desirable that light of sufficient intensity can be irradiated to a long distance. In contrast, in this embodiment, as shown in Figure 3B, the light intensity of the overlap area 53 of the measurement area 50 can be increased, which is advantageous for measuring long-distance distances.

<Optical conditions>
6A and 6B are explanatory diagrams of optical conditions. Fig. 6A is an explanatory diagram of the relationship between the light source 12 and the projection lens 16. Fig. 6B is an explanatory diagram of the relationship between the virtual image 12' of the light source 12 and the coupling lens 15.

As shown in Figure 6A, the focal length of the projection lens 16 is defined as f1. The distance from the principal point of the projection lens 16 to the light source 12 is defined as L1. The half length of the light source 12 in the Y direction is defined as y (the length from the optical axis of the projection optical system 14 to the end of the light source 12 is defined as y).

In this embodiment, the distance L1 from the principal point of the projection lens 16 to the light source 12 is smaller than the focal length f1 of the projection lens 16 (L1 < f1). Because the light source 12 is positioned closer than the focal point of the projection lens 16, the virtual image 12' of the light source 12 (the image of the light source 12 formed by the projection lens 16) is positioned on the opposite side of the light source 12 from the projection lens 16 (to the left of the light source 12 in the figure).

If the distance from the principal point of the projection lens 16 to the virtual image 12' is L', the relationship between L1, L' and f1 is given by the following equation (1).
(1/L1)-(1/L')=1/f1...(1)

Therefore, the distance L' from the principal point of the projection lens 16 to the virtual image 12' is given by the following equation (2).
L'=(L1×f1)/(f1-L1)...(2)

Furthermore, if the length from the optical axis of the light projection optical system 14 to the end of the virtual image 12' of the light source 12 is y', then y' is given by the following equation.
y'=y×(L'/L1)
=y×f1/(f1-L1)...(3)

Next, as shown in Fig. 6B , the focal length of first lens element 151 and second lens element 152 is defined as f2. Furthermore, the distance from the principal point of coupled lens 15 (the principal point of first lens element 151 or second lens element 152) to virtual image 12' is defined as L2. Here, as shown in Fig. 6B , if it is considered that coupled lens 15 irradiates the light of virtual image 12' onto a distant illumination area, the relationship between focal length f2 and distance L2 is as shown in the following equation (4).
L2=f2...(4)

The distance between the principal point of the projection lens 16 and the principal point of the coupling lens 15 is defined as d. Here, the distance L2 corresponds to the value obtained by adding the distance d to the distance L', and therefore the relationship between the focal lengths f1 and f2 and each distance is given by the following equation (5).
(L1×f1)/(f1-L1)+d=f2 (5)

6B , the distance between the optical axis of the light projection optical system 14 (projection lens 16) and the optical axis of the first lens element 151 (or the second lens element 152) is denoted by t and is referred to as the "shift amount t." Here, in order for the overlap area 53 to be formed, the first measurement area 51 and the second measurement area 52 must overlap. Therefore, the shift amount t must be smaller than the length y' from the optical axis of the light projection optical system 14 to the edge of the virtual image 12' of the light source 12 (t<y'). In other words, in order for the overlap area 53 to be formed, the shift amounts t of the first lens element 151 and the second lens element 152 of the coupled lens 15 must satisfy the following condition:
t<y×f1/(f1-L1) (6)

<Measurement Example 1>
FIG. 7 is an explanatory diagram of the light receiving sensor 22.

The light receiving sensor 22 has multiple pixels 221 arranged two-dimensionally. For example, in the case of a VGA light receiving sensor 22, 480 x 640 pixels 211 are arranged two-dimensionally. Each pixel 221 has a light receiving element, which outputs a signal according to the amount of light received. The control unit 30 acquires the output signal for each pixel 221.

Figure 8 is a timing chart illustrating an example of a measurement method.

The control unit 30 (timing control unit 34) causes the light source 12 of the irradiation unit 10 to emit pulsed light at a predetermined cycle. The upper part of Figure 8 shows the timing (emission timing) at which the light source 12 emits pulsed light. Here, light is emitted from the entire light-emitting surface of the light source 12. The light emitted from the light source 12 is irradiated onto the measurement area 50 via the light-projecting optical system 14. Light reflected from the surface of the object 90 within the measurement area 50 is received by the light-receiving sensor 22 via the light-receiving optical system 24. Each pixel 221 of the light-receiving sensor 22 receives the pulsed reflected light. The center of Figure 8 shows the timing (arrival timing) at which the pulsed reflected light arrives. Each pixel 221 outputs a signal corresponding to the amount of light received. The lower part of Figure 8 shows the output signal of each pixel 221.

The distance measurement unit 36 (signal processing unit 362) of the control unit 30 detects the arrival timing of the reflected light based on the output signal of each pixel 221. For example, the signal processing unit 362 detects the arrival timing of the reflected light based on the timing of the peak of the output signal of each pixel 221. Note that the signal processing unit 362 may determine the arrival timing of the reflected light based on the peak of a signal obtained by cutting the DC component of the output signal of the pixel 221 in order to remove the influence of ambient light (for example, sunlight).
Next, the distance measurement unit 36 (time detection unit 364) detects the time Tf from when light is emitted until the reflected light arrives, based on the light emission timing and the light arrival timing. The time Tf corresponds to the time it takes for light to travel back and forth between the measurement device 1 and the object 90. The distance measurement unit 36 (distance calculation unit 366) then calculates the distance L to the object 90 based on the time Tf. Note that when the time from when light is emitted until the reflected light arrives is Tf and the speed of light is C, the distance L is calculated as L = C × Tf/2. The control unit 30 generates a distance image by calculating the distance to the object 90 for each pixel 221 based on the time Tf detected for each pixel 221.

<Measurement Example 2>
FIG. 9A is an explanatory diagram of another example of the light receiving sensor 22.
The light receiving sensor 22 has a plurality of pixels 221 arranged two-dimensionally. Each pixel 221 has a plurality of light receiving elements 222. Here, each pixel 221 has nine SPADs (Single Photon Avalanche Diodes) arranged as the light receiving elements 222, three in the X direction and three in the Y direction. The light receiving elements 222 made up of SPADs output a pulse signal when they detect photons.

Figure 9B is an explanatory diagram of the signal processing unit 362. The signal processing unit 362 has an adder 362A, a comparator 362B, and a histogram generator 362C. Here, the signal processing unit generates a histogram used in time-correlated single photon counting (TCSPC) based on the output signals of each pixel 221 of the light-receiving sensor 22.

The adder 362A adds the output signals of the multiple light receiving elements 222 (SPAD) that make up the pixel 221. The adder 362A may add the output signals of the multiple light receiving elements 222 after adjusting (shaping) the pulse width output by the light receiving elements 222. The comparator 362B compares the output signal of the adder 362A with a threshold value, and outputs a signal if the output signal of the adder 362A is equal to or greater than the threshold value. The timing at which the comparator 362B outputs a signal is considered to be the timing at which the light receiving element 222 (SPAD) of the light receiving sensor 22 detects light.

Incidentally, photons of ambient light are incident on each light-receiving element 222 at random in time. In contrast, photons of reflected light are incident on each light-receiving element 222 with a predetermined delay (the flight time corresponding to the distance to the object 90) after the light is emitted. For this reason, when photons of ambient light are incident on the light-receiving element 222 at random in time, there is a low probability that the output signal of the adder 362A will exceed the threshold. On the other hand, when photons of reflected light are incident on the light-receiving element 222, the multiple light-receiving elements 222 that make up the pixel 221 detect the photons simultaneously, so there is a high probability that the output signal of the adder 362A will exceed the threshold. For this reason, the output signals of the multiple light-receiving elements 222 are added by the adder 362A, and the output signal of the adder 362A is compared with the threshold by the comparator 362B, thereby measuring the time at which the light-receiving element 222 (SPAD) is considered to have detected the reflected light.

Figure 9C is an explanatory diagram of a histogram. The horizontal axis in the diagram represents time, and the vertical axis represents frequency (number of times). The histogram generation unit 362C generates a histogram by repeatedly measuring the time at which the light receiving element 222 (SPAD) of the light receiving sensor 22 detects light based on the output of the comparison unit 362B, and incrementing the frequency (number of times) associated with that time. When incrementing the frequency (number of times), the histogram generation unit 362C may increase the number corresponding to the output signal (addition value) of the addition unit 362A instead of increasing the number by one.

The setting unit 32 (see Figure 1) presets the number of accumulations required to generate a histogram. The timing control unit 34 causes the light source 12 of the irradiation unit 10 to emit pulsed light multiple times according to the set number of accumulations. For each emission of pulsed light from the light source 12, the adder 362A outputs a signal once or multiple times. The histogram generation unit 362C generates a histogram by incrementing the frequency (number of times) according to the output signal of the comparator 362B until the set number of accumulations is reached.

After generating the histogram, the distance measurement unit 36 (time detection unit 364) detects the time Tf from when light is emitted until the reflected light arrives, based on the histogram. As shown in FIG. 9C, the distance measurement unit 36 (time detection unit 364) detects the time corresponding to the frequency peak in the histogram and sets this time as time Tf. The distance measurement unit 36 (distance calculation unit 366) then calculates the distance to the object 90 based on time Tf.

Normally, when measuring the distance to a distant object 90, the light irradiated onto the object 90 is weaker, so in order to measure the distance to the object 90 with high accuracy, it is necessary to increase the number of accumulations to generate a histogram. However, if the number of accumulations is increased, it takes longer to complete the histogram, which increases the time required to measure the distance (in other words, the frame rate (FPS) of the distance image decreases). In contrast, in this embodiment, the light intensity in the overlap area 53 of the measurement area 50 can be increased, which has the advantage of eliminating the need to increase the number of accumulations when measuring the distance to a distant object 90 in the overlap area 53.

Second Embodiment
In the first embodiment, the light source 12 emits light from the entire light-emitting surface at once. However, the light source 12 may be controlled to emit light from only a partial area of the light-emitting surface.

Figures 10A and 10B are explanatory diagrams showing the relationship between the light-emitting area of the light source 12 and the measurement area 50. Figure 10A is an explanatory diagram showing the relationship between the light-emitting area of the light source 12 and the measurement area 50 when light is irradiated onto the first measurement area 51 via the first lens element 151. Figure 10B is an explanatory diagram showing the relationship between the light-emitting area of the light source 12 and the measurement area 50 when light is irradiated onto the second measurement area 52 via the second lens element 152. To the right of each area of the measurement area 50 in Figures 10A and 10B, the light-emitting area of the corresponding light source 12 is shown.

The light source 12 is divided into multiple light-emitting regions in the Y direction, and here it is divided into 12 light-emitting regions (light-emitting regions #1 to #12). Note that the number of light-emitting regions of the light source 12 divided in the Y direction is not limited to 12. The measurement area 50 is also divided into multiple regions in the Y direction (regions A to P), and here it is divided into 16 regions. Note that the number of regions of the measurement area 50 divided in the Y direction is not limited to 16.

As shown in FIG. 10A, the first measurement area 51 corresponds to areas A to L. Light-emitting areas #1 to #12 of the light source 12 correspond to areas L to A of the first measurement area 51, respectively. For example, light emitted from light-emitting area #5 of the light source 12 is irradiated onto area H of the measurement area 50 via the first lens element 151.

As shown in FIG. 10B, the second measurement area 52 corresponds to areas E to P. Light-emitting areas #1 to #12 of the light source 12 correspond to areas P to E of the second measurement area 52, respectively. For example, light emitted from light-emitting area #5 of the light source 12 is irradiated onto area L of the measurement area 50 via the second lens element 152. In this way, light emitted from a certain light-emitting area of the light source 12 (e.g., light-emitting area #5) is irradiated onto two areas of the measurement area 50 (e.g., areas H and L) via the first lens element 151 and second lens element 152 of the coupled lens 15.

As shown in Figures 10A and 10B, overlapping area 53 corresponds to regions E to L. As shown in Figure 10A, light emitted from light-emitting regions #8 to #1 of light source 12 is irradiated onto regions E to L, which are overlapping area 53, via first lens element 151. Therefore, light-emitting regions #1 to #8 of light source 12 correspond to the aforementioned first region 121. Also, as shown in Figure 10B, light emitted from light-emitting regions #12 to #5 of light source 12 is irradiated onto regions E to L, which are overlapping area 53, via second lens element 152. Therefore, light-emitting regions #5 to #12 of light source 12 correspond to the aforementioned second region 122.

Figure 11 is an explanatory diagram of the state during measurement of area H, which is the overlap area 53. The corresponding light source 12 area is shown to the right of each area in the measurement area 50 in the figure. The corresponding area of the measurement area 50 is shown to the left of each pixel 221 of the light-receiving sensor 22 in the figure. Each pixel 221 of the light-receiving sensor 22 receives reflected light from the corresponding area of the measurement area 50 (an image of the measurement area 50 is formed on the light-receiving surface of the light-receiving sensor 22 by the light-receiving optical system 24).

Emission areas #5 and #9 of light source 12 are associated with area H of overlapping area 53. As shown in the figure, when measuring area H, control unit 30 simultaneously emits light from emission areas #5 and #9 of light source 12. In this way, when measuring a specific area of overlapping area 53, control unit 30 simultaneously emits light from the two emission areas corresponding to that area.

Light emitted from light-emitting region #5 of light source 12 is irradiated onto region H (first measurement area 51) and region L (second measurement area 52). Light emitted from region #9 of light source 12 is irradiated onto region D (first measurement area 51) and region H (second measurement area 52). In other words, the light emitted from regions #5 and #9 of light source 12 overlap in region H (overlapping area 53), which forms overlapping area 53, increasing the intensity of the light irradiated thereto.

Pixel #9 of the light-receiving sensor 22 receives reflected light from region H of the measurement area 50. Because light emitted from light-emitting regions #5 and #9 of the light source 12 overlap in region H, the intensity of the reflected light received by pixel #9 of the light-receiving sensor 22 can be increased.

In the explanation so far, the connected lens 15 has been used to increase the light intensity in the overlap area 53. However, the use of the connected lens 15 does not have to be to increase the light intensity in the overlap area 53.

For example, when measuring area H, the control unit 30 may separately calculate the distance by emitting light from light-emitting area #5 of the light source 12 and based on the light reception result of pixel #9 of the light-receiving sensor 22, and by emitting light from light-emitting area #9 of the light source 12 and based on the light reception result of pixel #9 of the light-receiving sensor 22. The control unit 30 may then calculate the distance by averaging the results of each distance calculation. In this way, the coupled lens 15 does not need to be used for the purpose of increasing the light intensity.

Figure 12 is an explanatory diagram of another measurement method.

Light emitted from a specific light-emitting region of the light source 12 is irradiated onto a corresponding region in the first measurement area 51 and a corresponding region in the second measurement area 52. In other words, light emitted from a specific light-emitting region of the light source 12 is irradiated onto two regions in the measurement area 50. For example, as shown in the figure, light emitted from light-emitting region #5 of the light source 12 is irradiated onto region H (first measurement area 51) and region L (second measurement area 52).

As shown in the figure, pixel #9 of the light receiving sensor 22 corresponds to region H of the measurement area 50 and receives reflected light from region H. Pixel #5 of the light receiving sensor 22 corresponds to region L of the measurement area 50 and receives reflected light from region L.

In this measurement method, by emitting light from a certain light-emitting region of the light source 12, it is possible to simultaneously measure the distance to the object 90 in two regions of the measurement area 50. In this way, the coupling lens 15 does not need to be used to increase the light intensity in the overlapping area 53.

===Summary===
The measuring device 1 includes a light source 12, a light projection optical system 14 that projects light from the light source 12 onto a measurement area 50, and a light receiving unit 20 that receives light reflected from the measurement area 50. The light projection optical system 14 includes a coupled lens 15 that connects a first lens element 151 and a second lens element 152. The optical axis of the first lens element 151 is shifted in the +Y direction (corresponding to the first direction), and the optical axis of the second lens element 152 is shifted in the −Y direction (the opposite direction to the direction in which the optical axis of the first lens element 151 is shifted). Light from the light source 12 is projected onto the first measurement area 51 via the first lens element 151, and onto the second measurement area 52, including the overlap area 53, via the second lens element 152. This measuring device 1 can project light over a wide range in the Y direction (corresponding to the first direction). Furthermore, since the overlapping area 53 is provided, it is possible to prevent the formation of an area between the first measurement area 51 and the second measurement area 52 that cannot be irradiated with light.

In the above-described measuring device 1, the ratio of the length in the Y direction (corresponding to the first direction) to the length in the X direction (corresponding to the second direction) is greater for the measurement area 50 than for the light source 12 (see Figures 3A and 3B). This allows the angle of view in the Y direction of the measurement area 50 to be widened.

In addition, in the above-described measuring device 1, by simultaneously emitting light from the first region 121 and the second region 122 of the light source 12, the light from the first region 121 of the light source 12 is irradiated onto the overlapping area 53 via the first lens element 151, and the light from the second region 122 of the light source 12 is irradiated onto the overlapping area 53 via the second lens element 152. This increases the intensity of the light irradiated onto the overlapping area 53 of the measurement area 50 (the hatched area in Figure 3B).

The above-mentioned projection optical system 14 has a projection lens 16 between the light source 12 and the connecting lens 15. By including the projection lens 16 in the projection optical system 14, it is possible to project the light from the light source 12 over a wide area. However, the projection optical system 14 does not have to have a projection lens 16 (in this case, the virtual image 12' in Figure 6B would be replaced with the light source 12, which would increase the size of the light source 12 and the measuring device 1).

In the above-described projection optical system 14, when the focal length of the projection lens 16 is f1, the distance from the principal point of the projection lens 16 to the light source 12 is L1, half the width of the light source 12 in the Y direction (corresponding to the first direction) is y, and the distance (shift amount) between the optical axis of the projection optical system 14 and the optical axis of the first lens element 151 in the Y direction is t, it is desirable that t < y × f1/(f1 - L1). This allows an overlap area 53 to be provided in the measurement area 50.

The control unit 30 of the measuring device 1 calculates the distance to the object 90 that reflects the reflected light based on the time it takes for the light source 12 to emit light and for the reflected light to be received. However, the measuring device 1 is not limited to measuring the distance to the object 90. For example, the measuring device 1 may measure the time it takes for the light source 12 to emit light and for the reflected light to be received, or may measure an image (brightness image) of the measurement area 50, without calculating the distance.

The control unit 30 of the above-described measuring device 1 generates a histogram by repeatedly measuring the time at which the light receiving element 222 of the light receiving unit 20 detects light, and detects the light arrival time Tf based on the peak of the histogram. When detecting the light arrival time Tf using a histogram in this way, it is particularly effective to use the coupled lens 15 of this embodiment to increase the light intensity in the overlap area 53 of the measurement area 50.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments and includes various modifications. Furthermore, the above embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those that include all of the described configurations. Furthermore, some of the configurations of the above embodiments can be added to, deleted from, or replaced with other configurations.

1 measurement device, 10 irradiation section,
12 light source, 12' virtual image,
121 first area, 122 second area,
14 Light projection optical system, 15 Connecting lens,
151 first lens element, 152 second lens element,
16 projection lens,
20 Light receiving unit, 22 Light receiving sensor,
221 pixel, 222 light receiving element,
24 Light receiving optical system,
30 control unit, 32 setting unit,
34 Timing control unit, 36 Distance measurement unit,
362 signal processing unit, 362A addition unit,
362B comparison unit, 362C histogram generation unit,
364 time detection unit, 366 distance calculation unit,
50 measurement area, 51 first measurement area,
52 second measurement area, 53 overlapping area,
90 Object

Claims (7)

A light source and
a light projection optical system that irradiates the light from the light source onto a measurement area;
a light receiving unit that receives reflected light from the measurement area;
Equipped with
the light source has a plurality of light-emitting regions arranged in a first direction,
The light projection optical system includes:
a coupled lens that couples a first lens element whose optical axis is shifted in the first direction and a second lens element whose optical axis is shifted in the opposite direction to the first lens element;
irradiating a first measurement area with light from the light source through the first lens element;
irradiating the light from the light source through the second lens element onto a second measurement area including an overlap area that overlaps with the first measurement area ;
Light is emitted from a specific light-emitting region among the plurality of light-emitting regions, and a predetermined region of the first measurement area is irradiated with the light via the first lens element, and a predetermined region of the second measurement area is irradiated with the light via the second lens element.
Measuring equipment. 2. The measuring device according to claim 1,
a ratio of a length in the first direction to a length in a second direction perpendicular to the optical axis and the first direction of the measurement area is greater than that of the light source;
Measuring equipment. 3. The measuring device according to claim 1 or 2,
By simultaneously emitting light from the first region and the second region of the light source,
irradiating the first region of light onto the overlapping area through the first lens element;
irradiating the second region of light onto the overlapping area through the second lens element;
Measuring equipment. The measuring device according to any one of claims 1 to 3,
The light projection optical system includes a projection lens between the light source and the coupling lens. 5. The measuring device according to claim 4,
The focal length of the projection lens is f1,
The distance from the principal point of the projection lens to the light source is L1,
y is half the width of the light source in the first direction;
a distance between the optical axis of the light projection optical system and the optical axis of the first lens element in the first direction is t;
When
t<y×f1/(f1-L1)
That is, the measuring device. The measuring device according to any one of claims 1 to 5,
a control unit that calculates a distance to an object that has reflected the reflected light based on a time taken for the light source to emit light and for the reflected light to be received;
Measuring equipment. 7. The measuring device according to claim 6,
The control unit
generating a histogram by repeatedly measuring the time at which the light receiving element of the light receiving unit detects light;
A measurement device that detects the arrival time based on a peak in the histogram.