Measuring equipment

Abstract

To expand a measurement area that can receive light without using a movable unit.SOLUTION: A measuring apparatus according to the present disclosure comprises: an irradiation unit that irradiates a measurement area with light; a light receiving sensor; and an optical system for light reception that causes the light receiving sensor to receive light reflected from the measurement area. The optical system for light reception has a connected lens obtained by connecting a first lens element whose optical axis is shifted in a first direction, and a second lens element whose optical axis is shifted in a direction opposite to the first lens element to each other, causes a light receiving device of the light receiving sensor to receive the reflected light from a first measurement area through the first lens element, and causes the light receiving device to receive the reflected light from a second measurement area including an overlapping area overlapping the first measurement area through the second lens element.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a measurement device. [Background technology]

[0002] 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 pulsed light is emitted until the reflected light is received. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-152536 Summary of the Invention [Problem to be solved by the invention]

[0004] In the device described in Patent Document 1, light is scanned by rotating a mirror, and the reflected light returning to the mirror is received by a light receiving unit. However, moving parts such as those that rotate the mirror are prone to malfunction. On the other hand, receiving light without using a moving part poses the problem of a narrower measurable range (measurement area).

[0005] An object of the present invention is to widen the measurement area in which light can be received without using any moving parts. [Means for solving the problem]

[0006] One aspect of the present invention for achieving the above object includes an irradiation unit that irradiates a measurement area with light, a light receiving sensor, and a light receiving optical system that causes the light receiving sensor to receive reflected light from the measurement area, wherein the light receiving optical system has a coupled lens that couples a first lens element whose optical axis is shifted in a first direction with a second lens element whose optical axis is shifted in an opposite direction to the first lens element, and causes the reflected light from the first measurement area to be received by a light receiving element of the light receiving sensor via the first lens element, and causes the reflected light from a second measurement area that includes an overlapping area that overlaps with the first measurement area to be received by the light receiving element via the second lens element. the light receiving sensor has a first light receiving element and a second light receiving element, the first light receiving element is capable of receiving light at a predetermined position on the measurement area through the first lens element, and the second light receiving element is capable of receiving light at the predetermined position on the measurement area through the second lens element; and a control unit that acquires a first light receiving result of the first light receiving element and a second light receiving result of the second light receiving element, the control unit generating a first histogram by repeatedly measuring the time when the first light receiving element detects light, generating a second histogram by repeatedly measuring the time when the second light receiving element detects light, generating a third histogram by combining the first histogram and the second histogram, and calculating the distance to the object at the predetermined position by detecting the arrival time from when light is emitted to when the reflected light is received based on a peak of the third histogram. It is a measuring device. Another aspect of the present invention for achieving the above object includes an irradiation unit that irradiates a measurement area with light, a light-receiving sensor, and a light-receiving optical system that causes the light-receiving sensor to receive reflected light from the measurement area, wherein the light-receiving optical system has a coupled lens that couples a first lens element whose optical axis is shifted in a first direction with a second lens element whose optical axis is shifted in an opposite direction to the first lens element, and causes the reflected light from the first measurement area to be received by a light-receiving element of the light-receiving sensor via the first lens element, and causes the reflected light from a second measurement area that includes an overlapping area that overlaps with the first measurement area to be received by the light-receiving element via the second lens element, and the light-receiving sensor has a first light-receiving element and a second lens element that couples the reflected light from the first measurement area with the second lens element. and a second light receiving element, wherein the first light receiving element is capable of receiving light at a predetermined position on the measurement area through the first lens element, and the second light receiving element is capable of receiving light at the predetermined position on the measurement area through the second lens element, and the control unit acquires a first light receiving result from the first light receiving element and a second light receiving result from the second light receiving element, and the control unit generates a histogram by repeatedly measuring the time when the first light receiving element detects light and the time when the second light receiving element detects light, and calculates the distance to an object at the predetermined position by detecting the arrival time from when light is emitted to when the reflected light is received based on the peak of the histogram.

[0007] Other problems and solutions disclosed in the present application will be made clear in the detailed description and drawings. [Effects of the Invention]

[0008] According to the present invention, it is possible to widen the measurement area capable of receiving light without using a moving part. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is an explanatory diagram of the overall configuration of a measurement device 1. As shown in FIG. [Figure 2] FIG. 2 is an explanatory diagram of the light receiving section 20. As shown in FIG. [Figure 3] Fig. 3A is an explanatory diagram of the light receiving sensor 22. Fig. 3B is an explanatory diagram of a measurement area 50. Fig. 3C is an explanatory diagram of an example in which the measurement device 1 is mounted on a vehicle. [Figure 4] FIG. 4 is an explanatory diagram of the arrangement of the pixels 221 of the light receiving sensor 22. As shown in FIG. [Figure 5] FIG. 5 is a perspective view of the coupling lens 25. As shown in FIG. [Figure 6] 6A and 6B are explanatory diagrams of the measurement area 50. FIG. [Figure 7]7A and 7B are explanatory diagrams showing the relationship between the pixels 221 (light receiving regions) of the light receiving sensor 22 and the measurement area 50. FIG. [Figure 8] 8A and 8B are explanatory diagrams of optical conditions. [Figure 9A] FIG. 9A is an explanatory diagram of an example of a measurement method. [Figure 9B] FIG. 9B is an explanatory diagram of an example of a measurement method. [Figure 9C] FIG. 9C is an explanatory diagram of an example of a measurement method. [Figure 10] FIG. 10 is a timing chart for explaining an example of a measurement method. [Figure 11] Fig. 11A is an explanatory diagram of another example of the light receiving sensor 22. Fig. 11B is an explanatory diagram of the signal processing unit 362. Fig. 11C is an explanatory diagram of a histogram. [Figure 12] FIG. 12 is an explanatory diagram of the signal processing unit 362 when measuring the overlapping area 53. [Figure 13] FIG. 13 is an explanatory diagram of another signal processing unit 362 when measuring the overlapping area 53. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, identical or similar components may be designated by common reference numerals, and redundant description may be omitted.

[0011] <Overall structure> FIG. 1 is an explanatory diagram of the overall configuration of a measurement device 1. As shown in FIG.

[0012] The measuring device 1 is a device that measures the distance to an object 90. The measuring device 1 is a device that has a function as a so-called LiDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging). The measuring device 1 emits measurement light, detects the reflected light reflected on the surface of the object 90, and measures the time from emitting the measurement light to receiving the reflected light, thereby measuring the distance to the object 90 using a TOF (Time of Flight) method. The measuring device 1 has an irradiation unit 10, a light receiving unit 20, and a control unit 30.

[0013] The irradiation unit 10 irradiates measurement light toward the object 90. The irradiation unit 10 irradiates a measurement area 50 (described later) with the measurement light 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.

[0014] 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 detailed configuration of the light receiving unit 20 will be described later.

[0015] The control unit 30 is responsible for controlling the measurement device 1. The control unit 30 controls the irradiation of light from the irradiation unit 10. The control unit 30 also measures the distance to the object 90 using a TOF (Time of Flight) method based on the output result 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 configured with an analog calculation circuit. The storage device is configured with a main storage device and an auxiliary storage device, and is a device that stores programs and data. The calculation unit executes the programs stored in the storage device, thereby performing various processes for measuring the distance to the object 90. Functional blocks of various processes are shown in the figure.

[0016] 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.

[0017] <Regarding the light receiving unit 20> 2 is an explanatory diagram of the light receiving unit 20. As already described, the light receiving unit 20 has a light receiving sensor 22 and a light receiving optical system 24.

[0018] In the following description, the direction along the optical axis of the light receiving optical system 24 is referred to as the Z direction. Note that the object 90 to be measured by the measurement device 1 is separated from the measurement device 1 in the Z direction. Also, the direction perpendicular to the Z direction, in which the first lens element 251 and the second lens element 252 that make up the coupled lens 25 (described later) are aligned, is referred to as the Y direction. Also, the direction perpendicular to the Z direction and the Y direction is referred to as the X direction.

[0019] 3A is an explanatory diagram of the light receiving sensor 22. FIG. 4 is an explanatory diagram of the arrangement of the pixels 221 of the light receiving sensor 22. The light-receiving sensor 22 has a light-receiving surface parallel to the XY plane (a surface parallel to the X and Y directions). The light-receiving surface is rectangular. Reflected light arriving from the measurement area is irradiated onto the light-receiving surface of the light-receiving sensor 22 via the light-receiving optical system 24 (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).

[0020] The light receiving sensor 22 has a plurality of pixels 221 arranged two-dimensionally. For example, in the case of a VGA light receiving sensor 22, 480 x 640 pixels 221 are arranged two-dimensionally. Each pixel 221 has a light receiving element, and the light receiving element outputs a signal according to the amount of received light. The control unit 30 acquires the output signal for each pixel 221.

[0021] The light receiving optical system has a coupling lens 25. FIG. The coupled lens 25 is an optical component in which a first lens element 251 and a second lens element 252 are coupled together. The first lens element 251 and the second lens element 252 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 251 is the same as the focal length of the second lens element 252. The first lens element 251 and the second lens element 252 each have an optical axis along the Z direction. The optical axis of the first lens element 251 is shifted in the +Y direction with respect to the optical axis of the light-receiving optical system 24 (the condenser lens 26 described later). On the other hand, the optical axis of the second lens element 252 is shifted in the -Y direction with respect to the optical axis of the light-receiving optical system 24. In other words, the optical axis of the second lens element 252 is shifted in the opposite direction to that of the first lens element 251.

[0022] The light-receiving optical system 24 also has a condenser lens 26. The condenser lens 26 is a lens arranged between the light-receiving sensor 22 and the coupling lens 25. The light-receiving optical system 24 has the condenser lens 26, which allows the light-receiving sensor 22 to receive reflected light from a wide range of measurement area 50. The light-receiving optical system 24 also has the condenser lens 26, which allows an image of the rectangular measurement area 50 to be formed on the rectangular light-receiving surface of the light-receiving sensor 22. The distance between the condenser lens 26 and the light-receiving sensor 22 is closer than the focal length of the condenser lens 26.

[0023] Fig. 3B is an explanatory diagram of the measurement area 50. Figs. 6A and 6B are explanatory diagrams of the measurement area 50. Fig. 6A is an explanatory diagram of how the light-receiving sensor 22 receives reflected light from the first measurement area 51 via the first lens element 251. Fig. 6B is an explanatory diagram of how the light-receiving sensor 22 receives reflected light from the second measurement area 52 via the second lens element 252.

[0024] 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 where the light-receiving sensor 22 receives reflected light via the first lens element 251 (in other words, the first lens element 251 is an optical element that causes the light-receiving sensor 22 to receive the light reflected from the first measurement area 51). The second measurement area 52 is an area where the light-receiving sensor 22 receives reflected light via the second lens element 252 (in other words, the second lens element 252 is an optical element that causes the light-receiving sensor 22 to receive the light reflected from the second measurement area 52). Because the first lens element 251 and the second lens element 252 are arranged side by side in the Y direction, the first measurement area 51 and the second measurement area 52 are arranged with a shift in the Y direction. This allows the measurement area 50 to be set long in the Y direction (in other words, it is possible to receive reflected light from a wide range in the Y direction).

[0025] 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 that cannot receive reflected light.

[0026] 7A and 7B are explanatory diagrams showing the relationship between the pixels 221 (light-receiving regions) of the light-receiving sensor 22 and the measurement area 50. FIG. 7A is an explanatory diagram showing the relationship between the pixels 221 of the light-receiving sensor 22 and the measurement area 50 when receiving reflected light from the first measurement area 51 via the first lens element 251. FIG. 7B is an explanatory diagram showing the relationship between the pixels 221 of the light-receiving sensor 22 and the measurement area 50 when receiving reflected light from the second measurement area 52 via the second lens element 252. In the diagrams, the corresponding region of the measurement area 50 is shown to the left of each pixel 221 of the light-receiving sensor 22. Each pixel 221 of the light-receiving sensor 22 receives reflected light from the corresponding region of the measurement area 50.

[0027] The light receiving sensor 22 has a plurality of pixels 221 (light receiving regions) arranged in the Y direction, and here, 12 pixels (pixels #1 to #12) are arranged in the Y direction. The number of pixels 221 arranged in the Y direction is not limited to 12 (for example, in the case of a VGA light receiving sensor 22, 640 pixels are arranged in the Y direction). The measurement area 50 is divided into a plurality of regions (regions A to P) in the Y direction, and here, it is divided into 16 regions. The number of regions in the measurement area 50 divided in the Y direction is not limited to 16.

[0028] 7A, the first measurement area 51 corresponds to areas A to L. Pixels #1 to #12 of the light receiving sensor 22 correspond to areas L to A of the first measurement area 51, respectively. For example, pixel #5 of the light receiving sensor 22 receives reflected light from area H of the measurement area 50 via the first lens element 251.

[0029] 7B, the second measurement area 52 corresponds to areas E to P. Pixels #1 to #12 of the light-receiving sensor 22 correspond to areas P to E of the second measurement area 52, respectively. For example, pixel #5 of the light-receiving sensor 22 receives reflected light from area L of the measurement area 50 via the second lens element 252. In this way, a certain pixel (e.g., pixel #5) of the light-receiving sensor 22 can receive reflected light from two areas (e.g., areas H and L) of the measurement area 50 via the first lens element 251 and the second lens element 252 of the coupled lens 25. In the following description, when a certain pixel (e.g., pixel #5) of the light receiving sensor 22 is capable of receiving reflected light from two positions (e.g., area H and area L) in the measurement area 50, of the two positions (e.g., area H and area L), the position (e.g., area H) that receives reflected light through the first lens element 251 may be referred to as the "first position," and the area (e.g., area L) that receives reflected light through the second lens element 252 may be referred to as the "second position."

[0030] Incidentally, when a pixel of the light-receiving sensor 22 can receive reflected light from two regions (first position and second position) in the measurement area 50, it is necessary to be able to determine whether the reflected light was received from the first position or the second position when the light-receiving element of that pixel receives the reflected light. Therefore, in this embodiment, the control unit 30 is configured to be able to control the position on the measurement area 50 to which light is irradiated by controlling the irradiation unit 10. The control unit 30 also controls the irradiation unit 10 so that light is not irradiated simultaneously onto the first position and the second position. As a result, for example, when light is irradiated onto region H in the measurement area 50 and the light-receiving element of pixel #5 of the light-receiving sensor 22 receives reflected light, the control unit 30 determines that the received light is reflected from region H, not region L, and can calculate the distance to the object 90 in region H based on the signal from the light-receiving element of pixel #5.

[0031] 7A and 7B, the overlapping area 53 corresponds to regions E to L. As shown in FIG. 7A, pixels #8 to #1 of the light-receiving sensor 22 receive reflected light from regions E to L of the overlapping area 53 via the first lens element 251. Also, as shown in FIG. 7B, pixels #12 to #5 of the light-receiving sensor 22 receive reflected light from regions E to L of the overlapping area 53 via the second lens element 252. Reflected light from a certain region of the overlapping area 53 (for example, region H) can be received by two pixels of the light-receiving sensor 22 (for example, pixels #5 and #9) via the first lens element 251 and the second lens element 252 of the coupled lens 25.

[0032] 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 (so-called aspect ratio) of the measurement area 50 is greater than that of the light-receiving sensor 22. 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-receiving sensor 22 (in other words, it can receive reflected light from a wide range in the Y direction).

[0033] 6A, an area of ​​the light receiving surface of the light receiving sensor 22 that receives reflected light from the overlap area 53 via the first lens element 251 is referred to as the "first area 22A." Also, as shown in FIG. 6B, an area of ​​the light receiving surface of the light receiving sensor 22 that receives reflected light from the overlap area 53 via the second lens element 252 is referred to as the "second area 22B." Light reflected from a certain point on the overlap area 53 can be received by a pixel 221 on the first area 22A of the light receiving sensor 22 and a pixel 221 on the second area 22B.

[0034] 3B, the overlapping area 53 (hatched area) is located in the center in the Y direction of the measurement area 50. In other words, as shown in FIG. 3B, reflected light from the center of the measurement area 50 (overlapping area 53) can be received by the pixels 221 on the first region 22A of the light-receiving sensor 22 via the first lens element 251, and can also be received by the pixels 221 on the second region 22B of the light-receiving sensor 22 via the second lens element 252.

[0035] 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, as shown in Fig. 3C, when the measurement device 1 is mounted on a vehicle, the area where long-distance measurement is required can be a relatively narrow range, but it is expected that the intensity of reflected light arriving from long distances will be weak. In contrast, in this embodiment, as shown in Fig. 3B, reflected light from the overlap area 53 of the measurement area 50 can be received by two pixels (pixels 221 in the first area 22A and the second area 22B) of the light-receiving sensor 22, which is advantageous for measuring long-distances.

[0036] <Optical conditions> 8A and 8B are explanatory diagrams of optical conditions. Fig. 8A is an explanatory diagram of the relationship between the light-receiving sensor 22 and the condenser lens 26. Fig. 8B is an explanatory diagram of the relationship between the virtual image 22' of the light-receiving sensor 22 and the coupling lens 25.

[0037] 8A, the focal length of the condenser lens 26 is defined as f1. Furthermore, the distance from the principal point of the condenser lens 26 to the light-receiving sensor 22 is defined as L1. Furthermore, half the length of the light-receiving sensor 22 in the Y direction is defined as y (the length from the optical axis of the light-receiving optical system 24 to the end of the light-receiving sensor 22 is defined as y).

[0038] In this embodiment, the distance L1 from the principal point of the condenser lens 26 to the light-receiving sensor 22 is smaller than the focal length f1 of the condenser lens 26 (L1 < f1). Since the light-receiving sensor 22 is arranged closer to the condenser lens 26 than the focal point thereof, the virtual image 22' of the light-receiving sensor 22 (the image of the light-receiving sensor 22 formed by the condenser lens 26) is arranged on the opposite side of the light-receiving sensor 22 as viewed from the condenser lens 26 (the left side of the light-receiving sensor 22 in the figure).

[0039] If the distance from the principal point of the condenser lens 26 to the virtual image 22' is L', the relationship among L1, L', and f1 is given by the following equation (1). (1 / L1) - (1 / L') = 1 / f1 ····(1)

[0040] Therefore, the distance L' from the principal point of the condenser lens 26 to the virtual image 22' is given by the following equation (2). L' = (L1 × f1) / (f1 - L1) ····(2)

[0041] Also, if the length from the optical axis of the light-receiving optical system 24 to the end of the virtual image 22' of the light-receiving sensor 22 is y', y' is given by the following equation. y' = y × (L' / L1) = y × f1 / (f1 - L1) ····(3)

[0042] Next, as shown in FIG. 8B, let the focal length of the first lens element 251 and the second lens element 252 be f2. Also, let the distance from the principal point of the coupling lens 25 (the principal point of the first lens element 251 or the second lens element 252) to the virtual image 22' be L2. Here, as shown in FIG. 8B, considering that the coupling lens 25 forms the reflected light from a distant irradiation area at the position of the virtual image 22', the relationship between the focal length f2 and the distance L2 is given by the following equation (4). L2 = f2 ····(4)

[0043] Note that let the distance between the principal point of the condenser lens 26 and the principal point of the coupling lens 25 be d. Here, since the distance L2 corresponds to the value obtained by adding the distance d to the distance L', the relationship between the focal lengths f1, f2 and each distance is given by the following equation (5). (L1×f1) / (f1-L1)+d=f2 ····(5)

[0044] Also, as shown in FIG. 8B, the distance between the optical axis of the light-receiving optical system 24 (condensing lens 26) and the optical axis of the first lens element 251 (or the second lens element 252) is defined as t and is referred to as the "shift amount t". Here, in order for the overlapping area 53 to be formed, the first measurement area 51 and the second measurement area 52 need to overlap. For this reason, the shift amount t needs to be smaller than the length y' from the optical axis of the light-receiving optical system 24 to the end of the virtual image 22' of the light-receiving sensor 22 (t < y'). That is, in order for the overlapping area 53 to be formed, the shift amount t of each of the first lens element 251 and the second lens element 252 of the connecting lens 25 needs to satisfy the condition of the following formula. t<y×f1 / (f1-L1) ····(6)

[0045] <Measurement Example 1> FIGS. 9A to 9C are explanatory diagrams of an example of the measurement method. On the right side of each area of the measurement area 50 in the figure, the light-emitting area of the corresponding light source 12 is shown. Also, on the left side of each pixel 221 of the light-receiving sensor 22 in the figure, the area of the corresponding measurement area 50 is shown.

[0046] The light source 12 is divided into a plurality of light-emitting areas in the Y direction, and here it is divided into 16 light-emitting areas (light-emitting areas #1 to #16). Note that the number of light-emitting areas of the light source 12 divided in the Y direction is not limited to 16. Each light-emitting area (light-emitting areas #1 to #16) of the light source 12 corresponds to each area (area P to area A) of the measurement area 50. The control unit 30 controls the position on the measurement area 50 to be irradiated with light by causing a specific light-emitting region from among the multiple light-emitting regions of the light source 12 to emit light. Here, the control unit 30 controls the light source 12 to emit light in order, starting with the bottom light-emitting region #16 in the figure. This causes the light to be irradiated in a scanning manner across regions A to P of the measurement area 50. By scanning the light irradiated onto the measurement area 50 in the Y direction, if a pixel of the light-receiving sensor 22 can receive reflected light from two positions (first position and second position) on the measurement area 50, it is possible to prevent light from being irradiated onto the two positions (first position and second position) simultaneously. Note that the control unit 30 does not have to sequentially illuminate the light-emitting regions arranged in the Y direction. For example, the control unit 30 may control the position on the measurement area 50 to be irradiated with light by causing the light-emitting regions to emit light in a random order. Furthermore, light may be irradiated simultaneously onto multiple regions of the measurement area 50, provided that the light is not irradiated simultaneously onto two positions (first position and second position) where a certain pixel of the light receiving sensor 22 can receive light. Furthermore, light may be scanned onto regions A to P of the measurement area 50 by rotating a mirror.

[0047] Fig. 10 is a timing chart for explaining an example of a measurement method. The upper part of Fig. 10 shows the timing (emission timing) at which the light-emitting region of the light source 12 emits pulsed light. The center of Fig. 10 shows the timing (arrival timing) at which the pulsed reflected light arrives. The lower part of Fig. 10 shows the output signal of the pixel 221 (light-receiving element).

[0048] The control unit 30 (timing control unit 34) causes the light source 12 to emit pulsed light at a predetermined cycle. After the pulsed light is emitted, 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 signals of the pixels 221 (light receiving elements). 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. The distance measurement unit 36 ​​(time detection unit 364) of the control unit 30 detects the time Tf from when the 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 the light is emitted until the reflected light arrives is Tf and the speed of light is C, the distance L is given by L = C × Tf / 2.

[0049] 9A, light emitted from light-emitting region #16 of light source 12 is irradiated onto region A of measurement area 50 (first measurement area 51) via light-projecting optical system 14. Pixel #12 of light-receiving sensor 22 receives reflected light from region A via light-receiving optical system 24 (first lens element 251). Controller 30 calculates the distance to object 90 in region A based on the output signal of pixel #12 of light-receiving sensor 22. After emitting light from light-emitting area #16 (in other words, after measuring area A), the control unit 30 sequentially causes light-emitting areas #15 to #13 to emit light, sequentially irradiating light onto areas B to D of the first measurement area 51, and sequentially calculating the distances to the object 90 in areas B to D based on the output signals from pixels #11 to #9 of the light-receiving sensor 22.

[0050] 9B, light emitted from light-emitting region #12 of light source 12 is irradiated onto region E of measurement area 50 via light-projecting optical system 14. Because region E belongs to overlapping area 53, reflected light from region E can be received by pixels #8 and #12 of light-receiving sensor 22 via first lens element 251 and second lens element 252 of coupled lens 25. The control unit 30 calculates the distance to the object 90 in area E based on the output signal of pixel #8 of the light-receiving sensor 22, and also calculates the distance based on the output signal of pixel #12 of the light-receiving sensor 22, and then calculates the average of the two calculated distances. This improves the accuracy and robustness of the distance calculation. Alternatively, the control unit 30 may calculate the distance based on the output signal of pixel #8 of the light-receiving sensor 22, and also calculate the distance based on the output signal of pixel #12 of the light-receiving sensor 22, and detect an abnormality when the difference between the two calculated distances is greater than a predetermined value. Alternatively, the control unit 30 may calculate the distance to the object 90 in area E based on the output signal of one of pixel #8 and pixel #12 of the light-receiving sensor 22. After emitting light from light-emitting area #12 (in other words, after measuring area E), control unit 30 sequentially causes light-emitting areas #11 to #5 to emit light, sequentially irradiates light onto areas F to L of overlapping area 53, and sequentially calculates the distance to object 90 in areas F to L based on the output signals of two pixels that receive reflected light.

[0051] As shown in FIG. 9C , light emitted from light-emitting region #4 of light source 12 is irradiated onto region M of measurement area 50 (second measurement area 52) via light-projecting optical system 14. Pixel #4 of light-receiving sensor 22 receives reflected light from region M via light-receiving optical system 24 (second lens element 252). Controller 30 calculates the distance to object 90 in region M based on the output signal of pixel #4 of light-receiving sensor 22. After light-emitting region #4 emits light (in other words, after measuring region M), controller 30 sequentially controls light-emitting regions #3 to #1 to emit light and sequentially irradiate regions N to P of second measurement area 52 with light. Based on the output signals of pixels #3 to #1 of light-receiving sensor 22, controller 30 sequentially calculates the distance to object 90 in regions N to P.

[0052] According to the above measurement method, the distance to the object 90 in each of the 16 divided regions (regions A to P) of the measurement area 50 can be calculated based on the output results of the light-receiving sensor 22, which has 12 pixels 221 (pixels #1 to #12) arranged in the Y direction. In this way, the light-receiving sensor 22 can receive reflected light over a wide range in the Y direction. For example, using a VGA (640 × 480 pixels) light-receiving sensor 22 with 640 pixels arranged in the Y direction, it is possible to obtain an image (distance image) of the measurement area 50 with a resolution of 840 pixels in the Y direction.

[0053] <Measurement example 2> FIG. 11A is an explanatory diagram of another example of the light receiving sensor 22. In FIG. 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 a photon.

[0054] 9A to 9C, in this measurement method, the control unit controls light source 12 to emit light in order, starting from light-emitting region #16 at the bottom of the drawing. As a result, light is irradiated onto regions A to P of measurement area 50 in a scanning manner.

[0055] First, as shown in Figure 9A, we will explain the case where light emitted from the light-emitting area #16 of the light source 12 is irradiated onto area A of the measurement area 50 (first measurement area 51) via the light-projecting optical system 14, and reflected light from area A is received by pixel #12 of the light-receiving sensor 22 via the light-receiving optical system 24 (first lens element 251).

[0056] 11B 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.

[0057] The adder 362A adds output signals from multiple light receiving elements 222 (SPAD) that make up the pixel 221 (here, pixel #12). The adder 362A may add output signals from 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 from the adder 362A with a threshold, and outputs a signal when the output signal from the adder 362A is equal to or greater than the threshold. 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.

[0058] 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 time (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, the probability that the output signal of the adder 362A will be equal to or greater than the threshold is low. 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 the probability that the output signal of the adder 362A will be equal to or greater than the threshold is high. 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.

[0059] 11C 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 increment a number corresponding to the output signal (addition value) of the addition unit 362A, instead of incrementing the number by one.

[0060] The setting unit 32 (see FIG. 1) presets the number of accumulations for generating 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.

[0061] After generating the histogram, the distance measuring 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. 11C, the distance measuring unit 36 ​​(time detection unit 364) detects the time corresponding to the frequency peak of the histogram and sets this time as time Tf. Then, the distance measuring unit 36 ​​(distance calculation unit 366) calculates the distance to the object 90 based on time Tf.

[0062] Next, as shown in Figure 9B, we will explain the case where light emitted from the light-emitting region #12 of the light source 12 is irradiated onto region E of the overlapping area 53 via the light-projecting optical system 14, and reflected light from region E is received by pixels #8 and #12 of the light-receiving sensor 22 via the first lens element 251 and the second lens element 252 of the light-receiving optical system 24.

[0063] 12 is an explanatory diagram of signal processing unit 362 when measuring overlap area 53. Signal processing unit 362 has an addition unit 362A, a comparison unit 362B, a histogram generation unit 362C, and a histogram synthesis unit 362D. Addition unit 362A, comparison unit 362B, and histogram generation unit 362C have already been explained, so explanation will be omitted.

[0064] The histogram synthesis unit 362D synthesizes two histograms (single histograms) generated by the two histogram generation units 362C into one histogram (composite histogram). The histogram synthesis unit 362D generates a composite histogram by synthesizing histograms (single histograms) based on two pixels associated with the overlapping area 53. Here, the histogram synthesis unit 362D generates a composite histogram by synthesizing two single histograms based on pixels #8 and #12 of the light receiving sensor 22 corresponding to area E. Because a composite histogram is generated by synthesizing two single histograms, a histogram with a predetermined number of integrations can be generated even if the number of integrations of the single histograms is half the predetermined number. Therefore, in measuring the overlapping area 53, a histogram with a set number of integrations can be generated quickly, allowing distance measurement to be performed quickly. Furthermore, as shown in Figure 3C, it is expected that the intensity of the reflected light from the overlapping area 53 will be weak. However, by combining the histograms (single histograms) based on the two pixels of the light receiving sensor 22 for the reflected light from the overlapping area 53 and measuring the distance to the object 90 based on the combined histogram, it is possible to suppress a decrease in the accuracy of distance measurement even if the intensity of the reflected light is weak.

[0065] FIG. 13 is an explanatory diagram of another signal processing unit 362 when measuring the overlapping area 53. The signal processing unit 362 includes an adder 362A, a comparator 362B, and a histogram generator 362C. The adder 362A adds output signals from multiple light receiving elements 222 (SPADs) constituting two pixels 221 (here, pixels #8 and #12) associated with the overlapping area 53. That is, the adder 362A essentially considers the two pixels 221 (here, pixels #8 and #12) associated with the overlapping area 53 as a single pixel and adds output signals from multiple light receiving elements 222 (SPADs) constituting that pixel. Compared to the adder 362A shown in FIG. 11B, the adder 362A shown in FIG. 13 adds twice as many output signals from the light receiving elements 222 (SPADs). The comparator 362B compares the output signal from the adder 362A with a threshold and outputs a signal if the output signal from the adder 362A is equal to or greater than the threshold.

[0066] The setting unit 32 (see FIG. 1) sets the threshold value of the comparison unit 362B (see FIG. 13) when measuring the overlapping area 53 to a higher value than the threshold value of the comparison unit 362B (see FIG. 11B) when measuring the measurement area 50 other than the overlapping area 53. This increases the probability that the light-receiving element 222 (SPAD) of the light-receiving sensor 22 has detected reflected light when the output signal of the addition unit 362A is equal to or greater than the threshold value. Because the number of output signals of the light-receiving element 222 (SPAD) added by the addition unit 362A is large, even if the threshold value is set to a high value, the frequency with which the comparison unit 362B outputs a signal to the histogram generation unit 362C is not reduced (the generation of a histogram for a predetermined number of integrations is not delayed). For this reason, it is permitted to set the threshold value of the comparison unit 362B shown in FIG. 13 to a high value.

[0067] The histogram generation unit 362C generates a histogram by repeatedly measuring the time at which the light receiving elements 222 (SPAD) of the light receiving sensor 22 detect light based on the output of the comparison unit 362B and incrementing the frequency (number of times) associated with that time. Compared to the signal processing unit 362 shown in FIG. 12, the signal processing unit 362 shown in FIG. 13 can reduce the memory capacity for storing data for generating a histogram and the amount of calculation required for generating a histogram. As shown in FIG. 3C, the intensity of reflected light from the overlapping area 53 is expected to be weak. However, because the light receiving elements 222 (SPAD) of two pixels of the light receiving sensor 22 receive the reflected light, a decrease in the accuracy of distance measurement can be suppressed even if the intensity of the reflected light is weak.

[0068] ===Summary=== The measuring device 1 includes an irradiation unit 10 that irradiates a measurement area 50 with light, a light-receiving sensor 22, and a light-receiving optical system 24 that causes the light-receiving sensor 22 to receive light reflected from the measurement area 50. The light-receiving optical system 24 has a coupled lens 25 that couples a first lens element 251 and a second lens element 252. The optical axis of the first lens element 251 is shifted in the +Y direction (corresponding to the first direction), and the optical axis of the second lens element 252 is shifted in the -Y direction (the opposite direction to the shift of the optical axis of the first lens element 251). The light reflected from the first measurement area 51 of the measurement area 50 is received by the light-receiving element of the light-receiving sensor 22 via the first lens element 251. The light reflected from the second measurement area 52, including the overlap area 53, is received by the light-receiving element of the light-receiving sensor 22 via the second lens element 252. Such a measuring device 1 can receive reflected light from 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 where reflected light cannot be received.

[0069] The control unit 30 controls the position on the measurement area 50 to which light is irradiated. This makes it possible to irradiate a predetermined position on the measurement area 50 with light, or to prevent a predetermined position on the measurement area 50 from being irradiated with light.

[0070] A certain pixel (e.g., pixel #5 shown in FIGS. 7A and 7B) of the light receiving sensor 22 can receive reflected light from two positions (a first position and a second position; e.g., area H and area L) in the measurement area 50. In such a case, the control unit 30 controls the irradiation unit 10 so as not to simultaneously irradiate light onto both the first position (e.g., area H) in the first measurement area 51 and the second position (e.g., area L) in the second measurement area 52, from which the pixel (e.g., pixel #5) can receive light. This makes it possible to determine from which of the two positions on the measurement area 50 the reflected light was received when the light receiving element of that pixel receives reflected light.

[0071] 9B, reflected light from region E (predetermined position) of overlapping area 53 can be received by the light receiving element (first light receiving element) of pixel #8 of light receiving sensor 22 via first lens element 251, and can also be received by the light receiving element (second light receiving element) of pixel #12 of light receiving sensor 22 via second lens element 252. In this way, by enabling reflected light from the same position to be received by two light receiving elements, robustness can be improved.

[0072] Furthermore, when light is irradiated onto region E (predetermined position) of overlapping area 53, control unit 30 acquires an output signal (first light-receiving result) from the light-receiving element of pixel #8 of light-receiving sensor 22 and an output signal (second light-receiving result) from the light-receiving element of pixel #12. In this way, robustness can be improved by acquiring output signals (light-receiving results) from two light-receiving elements that receive reflected light from the same position.

[0073] Furthermore, the control unit 30 calculates the distance to the object 90 in region E based on the output signal (first light receiving result) of the light receiving element of pixel #8 of the light receiving sensor 22, and calculates the distance to the object 90 in the same region E based on the output signal (second light receiving result) of the light receiving element of pixel #12. In this way, by calculating the distances based on the output signals (light receiving results) of the two light receiving elements that received reflected light from the same position, robustness can be improved.

[0074] The control unit 30 may also detect an abnormality based on the distance calculated based on the output signal (first light-receiving result) of pixel #8 of the light-receiving sensor 22 and the distance calculated based on the output signal (second light-receiving result) of pixel #12. This makes it possible to determine whether there is any malfunction in the measurement device 1.

[0075] As shown in FIG. 12, the control unit 30 may generate a single histogram (first histogram) by repeatedly measuring the time when the light receiving element (first light receiving element) of pixel #8 of the light receiving sensor 22 detects light, generate a single histogram (second histogram) by repeatedly measuring the time when the light receiving element (second light receiving element) of pixel #12 detects light, and generate a composite histogram (third histogram) by combining the two single histograms. In this case, the control unit 30 can detect the arrival time Tf (see FIG. 11C) of light based on the peak of the composite histogram (third histogram) and calculate the distance to the object based on the detected arrival time Tf. This allows a composite histogram (third histogram) with a predetermined number of integrations to be generated even if the number of integrations of the single histograms (first histogram and second histogram) is half the predetermined number, thereby enabling high-speed distance measurement.

[0076] As shown in FIG. 13, the control unit 30 may generate a histogram by repeatedly measuring the time when the light receiving element (first light receiving element) of pixel #8 of the light receiving sensor 22 detects light and the time when pixel #12 (second light receiving element) detects light. Thereby, it is possible to reduce the capacity of the memory for storing data for generating the histogram and to reduce the amount of calculation for generating the histogram. Even in this case, the control unit 30 can detect the light arrival time Tf (see FIG. 11C) based on the peak of the histogram, and calculate the distance to the object based on the detected arrival time Tf.

[0077] The above light receiving optical system 24 has a condenser lens 26 between the light receiving sensor 22 and the coupling lens 25. By having the condenser lens 26 in the light receiving optical system 24, it becomes possible to make the light receiving sensor 22 receive reflected light from a wide range. However, the light receiving optical system 24 may not have the condenser lens 26 (in this case, since the light receiving sensor 22 having a light receiving surface with the size of the virtual image 22' in FIG. 8B will be replaced, the light receiving sensor 22 and the measuring device 1 will be enlarged).

[0078] In the above light receiving optical system 24, when the focal length of the condenser lens 26 is f1, the distance from the principal point of the condenser lens 26 to the light receiving sensor 22 is L1, the length of half of the width of the light receiving sensor 22 in the Y direction (corresponding to the first direction) is y, and the distance (shift amount) between the optical axis of the light receiving optical system 24 and the optical axis of the first lens element 251 in the Y direction is t, it is desirable that t < y × f1 / (f1 - L1). Thereby, an overlapping area 53 can be provided in the measurement area 50.

[0079] As described above, the embodiments of the present invention have been described in detail, but the present invention is not limited to the above embodiments and includes various modifications. Also, the above embodiments are those in which the configuration has been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Also, for a part of the configuration of the above embodiments, it is possible to add, delete, or replace with other configurations.

Explanation of Reference Numerals

[0080] 1 measurement device, 10 irradiation section, 12 light source, 14 light projection optical system, 20 light receiving unit, 22 light receiving sensor, 221 pixel, 222 light receiving element, 22A 1st area, 22B 2nd area, 24 Light receiving optical system, 25 connected lenses, 251 first lens element, 252 second lens element, 26 condenser lens, 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, 362D histogram synthesis unit, 364 time detection unit, 366 distance calculation unit, 50 measurement area, 51 first measurement area, 52 second measurement area, 53 overlapping area, 90 Objects

Claims

1. an irradiation unit that irradiates a measurement area with light; A light receiving sensor; a light receiving optical system for receiving reflected light from the measurement area by the light receiving sensor; Equipped with The light receiving optical system includes: a coupled lens that couples a first lens element whose optical axis is shifted in a first direction and a second lens element whose optical axis is shifted in a direction opposite to that of the first lens element; The reflected light from the first measurement area is received by a light receiving element of the light receiving sensor via the first lens element; The reflected light from a second measurement area including an overlap area overlapping with the first measurement area is received by the light receiving element via the second lens element; the light receiving sensor includes a first light receiving element and a second light receiving element; the first light receiving element is capable of receiving light at a predetermined position on the measurement area through the first lens element; the second light receiving element is capable of receiving light at the predetermined position on the measurement area via the second lens element; a control unit that acquires a first light receiving result of the first light receiving element and a second light receiving result of the second light receiving element, The control unit generating a first histogram by repeatedly measuring the time at which the first light receiving element detects light; generating a second histogram by repeatedly measuring the time at which the second light receiving element detects light; generating a third histogram by combining the first histogram and the second histogram; calculating a distance to the object at the predetermined position by detecting a time taken for the light to reach the object from when the light is emitted until when the reflected light is received based on a peak of the third histogram; Measuring equipment.

2. an irradiation unit that irradiates a measurement area with light; A light receiving sensor; a light receiving optical system for receiving reflected light from the measurement area by the light receiving sensor; Equipped with The light receiving optical system includes: a coupled lens that couples a first lens element whose optical axis is shifted in a first direction and a second lens element whose optical axis is shifted in a direction opposite to that of the first lens element; The reflected light from the first measurement area is received by a light receiving element of the light receiving sensor via the first lens element; The reflected light from a second measurement area including an overlap area overlapping with the first measurement area is received by the light receiving element via the second lens element; the light receiving sensor includes a first light receiving element and a second light receiving element; the first light receiving element is capable of receiving light at a predetermined position on the measurement area through the first lens element; the second light receiving element is capable of receiving light at the predetermined position on the measurement area via the second lens element; a control unit that acquires a first light receiving result of the first light receiving element and a second light receiving result of the second light receiving element, The control unit generating a histogram by repeatedly measuring the time when the first light receiving element detects light and the time when the second light receiving element detects light; calculating a distance to the object at the predetermined position by detecting a time taken for the light to reach the object from when the light is emitted until when the reflected light is received based on a peak of the histogram; Measuring equipment.

3. A measuring device according to claim 1 or 2, the control unit controls a position on the measurement area to which the irradiation unit irradiates the light. Measuring equipment.

4. A measuring device according to claim 3, the control unit controls the irradiation unit so that, when a light-receiving element of the light-receiving sensor can receive light at a first position in the first measurement area and at a second position in the second measurement area, the light is not irradiated to the first position and the second position simultaneously. Measuring equipment.

5. A measuring device according to any one of claims 1 to 4, The light receiving optical system includes a condenser lens between the light receiving sensor and the coupling lens.

6. A measuring device according to claim 5, The focal length of the condenser lens is f1, The distance from the principal point of the condenser lens to the light receiving sensor is L1, y is half the width of the light receiving sensor in the first direction, a distance between the optical axis of the light receiving 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.

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