Distance measuring device and distance measuring system

Abstract

To increase accuracy of measuring a distance by a limited size of a device.SOLUTION: The present invention includes: a plurality of light projection units for projecting light on a measurement target range; a plurality of light receiving units for receiving light reflected by an object in the measurement target range; and a distance measuring control unit for calculating a distance to the target object on the basis of timing when the light projection units project light and timing when the light receiving units receive light. The number of the light receiving units is larger than the number of the light projection units.SELECTED DRAWING: Figure 1-1

Description

Technical Field

[0001] The present invention relates to a distance measuring device and a distance measuring system.

Background Art

[0002] One of the methods for measuring the distance from an imaging device to a subject is a method called TOF (Time Of Flight), in which distance measuring light is irradiated toward the subject, and the distance is calculated from the time difference of the reflected light. In this method, after irradiating the subject with distance measuring light using infrared light intensity-modulated by a predetermined irradiation pattern, the distance measuring light reflected by the subject is received by an imaging element for infrared rays, and the time difference from irradiation to reception is detected for each pixel to calculate the distance. The calculated distance values are collected in a bitmap form for each pixel and stored as a "distance image". A distance image generation device (distance measuring device) of such a method is called a TOF camera.

[0003] For example, Patent Document 1 discloses a distance measuring device which is an omnidirectional imaging device that acquires omnidirectional three-dimensional information at once using a plurality of sensors and cameras.

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the technique disclosed in Patent Document 1, there is room for improvement in distance measurement accuracy.

[0005] The present invention has been made in view of the above, and an object thereof is to improve distance measurement accuracy with a limited device size.

Means for Solving the Problems

[0006] In order to solve the above-described problems and achieve the object, the present invention A part of each field of view overlaps, a plurality of light projecting units that irradiate light on a range of a measurement target; A part of each field of view overlaps, a plurality of light receiving units that receive light reflected by an object in the range of the measurement target, and the plurality of light projecting units of light projectiona light emission control unit that controls the plurality of light receiving units of light reception a light reception processing unit that controls comprises a distance measurement control unit, and the number of the plurality of light receiving units is larger than the number of the plurality of light projecting units ku , Each of the plurality of light reception units faces a direction different from any of the plurality of light projection units. The plurality of light reception units include a first light reception unit facing a first direction and a plurality of second light reception units facing a direction different from the first direction. The first light reception unit, the plurality of second light reception units, and the plurality of light projection units are arranged in this order from one end side of the housing. which is characterized in that

Advantages of the Invention

[0007] According to the present invention, by making the number of light receiving units larger than the number of light projecting units, it is possible to increase the intensity of the light projected by the light projecting units, increase the focal length of the light receiving units, and improve the distance measurement accuracy with a limited device size, thereby achieving the effect described above.

Brief Description of the Drawings

[0008]

Figure 1-1

Figure 1-2

Figure 1-3

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7-1

Figure 7-2

Figure 7-3

Figure 8

Figure 9-1

Figure 9-2

Figure 10

Figure 11-1

Figure 11-2

Figure 11-3

Figure 12-1

Figure 12-2

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Embodiments for Carrying Out the Invention

[0009] Embodiments of a distance measuring device and a distance measuring system will be described in detail with reference to the attached drawings below.

[0010] (First Embodiment) Here, FIG. 1-1 is an external perspective view showing the configuration of the imaging device 100 according to the first embodiment, FIG. 1-2 is a perspective view showing the internal configuration of the imaging device 100, and FIG. 1-3 is a perspective view showing an enlarged view of the vicinity of the shutter button 62 of the imaging device 100. The imaging device 100 functions as a distance measuring device using the TOF (Time Of Flight) method.

[0011] As shown in FIGS. 1-1 to 1-3, the imaging device 100 includes a VCSEL (Vertical Cavity Surface Emitting Laser) light projecting unit 21, a TOF light receiving unit 61, a CMOS (Complementary Metal Oxide Semiconductor) light receiving unit 30, substrates (CMOS substrate 35, VCSEL substrates 22F and 22B, main substrate 41), and a fan 38.

[0012] The VCSEL light projecting unit 21 irradiates distance measuring light (such as infrared light) toward an object to be measured for the purpose of measuring the distance to the subject. The VCSEL light projecting unit 21 is composed of two VCSEL light projecting units 21 (VCSEL light projecting units 21F and 21B), details of which will be described later (see FIG. 5).

[0013] The TOF light receiving unit 61 receives reflected light (scattered light) from the object irradiated with the distance measuring light by the VCSEL light projecting unit 21 and acquires three-dimensional point cloud data.

[0014] The CMOS light receiving unit 30 acquires a two-dimensional image by a CMOS sensor 33 (see FIG. 8).

[0015] The substrates (CMOS substrate 35, VCSEL substrates 22F and 22B, main substrate 41) are substrates for driving / controlling the VCSEL light emitting unit 21, the TOF light receiving unit 61, and the CMOS light receiving unit 30. The substrates (CMOS substrate 35, VCSEL substrates 22F and 22B, main substrate 41) are connected to the VCSEL light emitting unit 21, the TOF light receiving unit 61, and the CMOS light receiving unit 30 respectively by cables, FPCs, FFCs, etc.

[0016] The fan 38 is provided inside the imaging device 100 to generate forced convection and cool the inside of the imaging device 100.

[0017] Here, the arrangement of the plurality of substrates (CMOS substrate 35, VCSEL substrates 22F and 22B, main substrate 41) included in the imaging device 100 will be described.

[0018] As shown in FIG. 1-2, the CMOS substrate 35 is arranged (aligned in the Z-axis direction) so as to be sandwiched between two VCSEL substrates 22F and 22B. Further, the main substrate 41 for overall control / driving of the imaging device 100 is also arranged in a state parallel to the above three substrates. The main substrate 41 is arranged outside (-Z side; closer to the rear cover 12) than the VCSEL substrate 22B.

[0019] By configuring it in this way, a total of four substrates (VCSEL substrates 22F and 22B, CMOS substrate 35, main substrate 41) can be housed inside the imaging device 100 without wasting the space inside the imaging device 100. As a result, the size in the arrangement direction (Z-axis direction) of the four substrates (VCSEL substrates 22F and 22B, CMOS substrate 35, main substrate 41) can be reduced. Further, since the four substrates (VCSEL substrates 22F and 22B, CMOS substrate 35, main substrate 41) are arranged to be parallel to each other, an air flow along the substrates will be generated without disturbing natural convection inside the imaging device 100 or forced convection by the fan 38, and the occurrence of temperature deviation inside the device can be reduced. Furthermore, since the exhaust heat efficiency due to the inflow / outflow of air from the ventilation holes provided in the cover member described later and heat dissipation (heat transfer) from the cover member to the external air is improved, the occurrence of temperature rise inside the device can be reduced.

[0020] Also, as shown in FIGS. 1-1 to 1-3, the imaging device 100 includes battery cases 68a and 68b (see FIG. 3) for housing the batteries 18a and 18b, a shutter button 62, and an operation switch unit 17.

[0021] The shutter button 62 is a button that a user operates to determine the shooting timing of the CMOS light receiving unit 30.

[0022] The operation switch unit 17 is a switch that a user operates to switch the power ON / OFF of the imaging device 100 and to switch the operation mode.

[0023] Furthermore, as shown in FIGS. 1-1 to 1-3, the imaging device 100 includes cover members (front cover 11, rear cover 12, left cover 13, right cover 14, battery covers 15a and 15b, bottom plate 16, inner wall 10 (see FIG. 2), etc.) for holding the above components.

[0024] As shown in Fig. 1-1, the imaging device 100 has a screw hole 19 on the bottom plate 16 (-X side) for fixing to a tripod or the like in order to prevent camera shake during shooting. The imaging device 100 fixed to a tripod or the like in the screw hole 19 can obtain a more stable image than when the user holds the imaging device 100 and shoots. Further, when the imaging device 100 is fixed to a tripod or the like, remote operation is more effective.

[0025] Here, the inner wall 10, which is a part of the cover member of the imaging device 100, will be described. Fig. 2 is a diagram showing an example of the inner wall 10.

[0026] As shown in Fig. 2, the inner wall 10 connects the front cover 11 and the rear cover 12. In a conventional cover member (exterior) alone, the rigidity is likely to decrease due to the monocoque structure, but in the imaging device 100 of the present embodiment, by connecting the front cover 11 and the rear cover 12 with the inner wall 10, it is possible to increase the rigidity.

[0027] Next, the battery cases 68a and 68b will be described. Fig. 3 is a diagram showing an example of the battery cases 68a and 68b.

[0028] As shown in Fig. 3, the imaging device 100 incorporates batteries 18a and 18b therein. Therefore, the imaging device 100 can reduce the burden of carrying and shooting work. The imaging device 100 fixes a battery circuit board 67 on which battery cases 68a and 68b are mounted to both surfaces (+Y side and -Y side surfaces) of the inner wall 10. The battery cases 68a and 68b house the batteries 18a and 18b.

[0029] The imaging device 100 can attach and detach the batteries 18a and 18b in the Y-axis direction by removing the battery covers 15a and 15b shown in Fig. 1-1, so that the replacement work of the batteries 18a and 18b can be facilitated.

[0030] Incidentally, the imaging device 100 may be driven using a power cord (not shown). It is desirable that the power cord be detachable. This eliminates the need to incorporate a battery in the main body of the imaging device 100, thereby enabling weight reduction of the imaging device 100 and extension of the shooting time.

[0031] Also, when driving the imaging device 100 using a power cord, it is desirable to dispose the insertion port of the power cord on the bottom (bottom plate 16) side (-X side) rather than the shutter button 62. This allows the user's finger to be irradiated with light before the power cord, reducing the dead angle caused by the power cord compared to the dead angle caused by the user's finger or the like pressing the shutter button 62.

[0032] Here, the shutter button 62 will be described. Here, FIG. 4 is a diagram showing a cross section of the shutter button 62.

[0033] As shown in FIG. 4, the imaging device 100 includes a switch 69 on the -Z side surface of the main board 41. The imaging device 100 also includes a shutter button 62 coaxially with the switch 69 on the rear cover 12. With such a configuration, the shutter button 62 can directly press the switch 69, realizing reduction in the number of parts and simplification of the structure. Also, since the shutter button 62 can directly press the switch 69, the switch 69 can be reliably activated. If the positions of the shutter button 62 and the switch 69 are separated, they may be connected via an intermediate member.

[0034] As shown in FIG. 4, the imaging device 100 includes a spring member 63 between the main board 41 and the shutter button 62. The spring member 63 is a component for pushing the shutter button 62 back to a predetermined position when the user releases the shutter button 62 after pressing it.

[0035] Next, the arrangement of the shutter button 62 will be described. Here, FIG. 5 is a diagram showing the configuration near the shutter button 62.

[0036] As shown in FIG. 5, the imaging device 100 includes a shutter button 62 in an area where a blind spot is generated by various cover members (in this embodiment, the rear cover 12).

[0037] Specifically, in the X-Z cross-section shown in FIG. 5, the outermost angle of view (lower side; -X side) of the emitted light from the VCSEL light projection unit 21F is θa, and it is possible to secure up to about θa = 90°. On the other hand, regarding the emitted light from the VCSEL light projection unit 21B, a part of the rear cover 12 that houses the main board 41 protrudes in the -Z direction. Therefore, the outermost angle of view is θb, so θb < θa. Therefore, as shown in FIG. 5, when the shutter button 62 is arranged near the arrow V in the rear cover 12, the light beam (emitted light beam B) of the outermost angle of view θb will not be blocked by the user's finger. However, when the shutter button 62 is provided on the opposite side (front cover 11 side), the light beam (emitted light beam A) of θa (≈90°) will be blocked by the user's finger, resulting in a narrower angle of view, which is not preferable.

[0038] Also, the shutter button 62 is arranged between the TOF light receiving unit 61 and the batteries 18a, 18b. By arranging the shutter button 62 between the TOF light receiving unit 61 and the batteries 18a, 18b in this way, the part where the batteries 18a, 18b are housed (a location close to the center of gravity) will be gripped, so it is possible to reduce fatigue and prevent camera shake.

[0039] Note that instead of determining the shooting timing by pressing / releasing the shutter button 62 provided on the rear cover 12 of the imaging device 100, it may be configured to perform remote operation via wire or wireless. In the case of such a remotely operable configuration, the imaging device 100 can improve the anti-shake effect.

[0040] Here, FIG. 6 is a diagram showing a cross section near the shutter button 62. As shown in FIG. 6, the imaging device 100 includes a plurality of LED elements 65 (five in FIG. 6) on the -Z side surface of the main board 41 to represent the operating state of the imaging device 100. Further, the imaging device 100 includes an opening 64 in the rear cover 12 so as to be coaxial with the emission optical axis of the LED element 65. With such a configuration, the imaging device 100 can efficiently emit the light emitted from the LED element 65 to the outside through the opening 64.

[0041] Note that the imaging device 100 may be connected between the LED element 65 and the opening 64 with a light guide plate, an optical fiber, or the like. Thereby, the imaging device 100 can improve the light utilization efficiency. Further, the imaging device 100 can further improve the visibility of the light emitted from the LED element 65 by providing a lens system or a diffusion plate in the opening 64.

[0042] Next, the VCSEL light projection unit 21 will be described. Here, FIG. 7-1 is a perspective view showing the VCSEL light projection unit 21, FIG. 7-2 is a diagram showing a cross section of the VCSEL optical system 23, and FIG. 7-3 is a diagram showing an arrangement example of the VCSEL light projection unit 21.

[0043] As shown in FIGS. 7-1 to 7-3, the VCSEL light projection unit 21 includes a VCSEL substrate 22, a VCSEL package 24, and a lens cell 26.

[0044] The VCSEL package 24 is a light source having a VCSEL (vertical cavity surface emitting laser) as a light emitting point 25. The lens cell 26 houses a VCSEL optical system 23 composed of a plurality of lenses.

[0045] The VCSEL substrate 22 (VCSEL substrates 22F, 22B) fixes the VCSEL package 24 by soldering. Further, the VCSEL substrate 22 fixes the VCSEL optical system 23 (that is, the lens cell 26) by a method such as screwing or adhesion in a state where it is aligned with the light emitting point 25 with a predetermined accuracy.

[0046] The VCSEL substrate 22 (VCSEL substrates 22F and 22B) mounts a drive circuit for driving the VCSEL package 24. Since a large current flows through the drive circuit of the VCSEL substrate 22 to increase the intensity of the light emitted from the VCSEL package 24 which is a light source, heat is generated. Therefore, the VCSEL substrate 22 mounts a drive circuit with a large allowable current and a heat dissipation member (for example, a heat sink) in order to reduce the heat generation of the drive circuit. For this reason, the VCSEL substrate 22 is made larger than other substrates (such as the CMOS substrate 35). With such a configuration, in the imaging device 100, it is difficult for the VCSEL substrate 22 to overheat, so that light with a high intensity can be projected from the VCSEL light projecting unit 21.

[0047] As shown in FIG. 7-3, the VCSEL light projecting units 21 (VCSEL light projecting units 21F and 21B) are arranged such that the emission optical axis of the VCSEL optical system 23 is parallel to the Z-axis direction, and the two VCSEL light projecting units 21 (VCSEL light projecting units 21F and 21B) are arranged in opposite directions to each other.

[0048] The VCSEL optical system 23 has the function of a fisheye lens. In a situation where light rays are not blocked by surrounding components or the like, the VCSEL optical system 23 irradiates an area of the entire sphere (4π [sr]) as the measurement target range with two VCSEL light projecting units 21F and 21B which are a plurality of light projecting parts.

[0049] Here, the measurement target range is an area within the entire sphere (4π [sr]) region centered on the imaging device 100 that can be irradiated with light by two VCSEL light projecting units 21F and 21B which are a plurality of light projecting parts. As described above, the measurement target range corresponds to the entire sphere (4π [sr]) in the case of a situation where light rays are not blocked by surrounding components or the like around the VCSEL light projecting units 21F and 21B. On the other hand, when light rays are blocked by components around the VCSEL light projecting units 21F and 21B, the measurement target range is the range that can be light-projected without being blocked by the components around the light projecting parts within the area of the entire sphere.

[0050] The imaging device 100 fixes the VCSEL light projecting units 21F and 21B respectively by fastening screws 66a (see FIG. 10) to the front cover 11 and the rear cover 12. When fastening the screws, the positioning parts provided on the lens cells 26 of the VCSEL light projecting units 21F and 21B are positioned corresponding to the positioning parts on the front cover 11 and the rear cover 12 sides. Thereby, the alignment accuracy of the VCSEL light projecting unit 21F with respect to the front cover 11 and the alignment accuracy of the VCSEL light projecting unit 21B with respect to the rear cover 12 can be maintained.

[0051] With such a configuration, it is possible to suppress variations in the amount (light quantity) of the emitted light from the VCSEL light projecting units 21F and 21B being blocked by the front cover 11, the rear cover 12, etc. due to machining errors (dimensional errors and shape errors) of the components of the imaging device 100 and the influence of assembly variations. As a result, the imaging device 100 can avoid deterioration of the illuminance distribution of the emitted light.

[0052] Note that the VCSEL substrates 22F and 22B are arranged parallel to each other as shown in FIG. 10 described later. The VCSEL substrates 22F and 22B need to be enlarged in order to reduce overheating caused by emitting light of high intensity from the VCSEL light projecting units 21F and 21B. By arranging the VCSEL substrates 22F and 22B with larger sizes parallel to each other in this way, the VCSEL substrates 22F and 22B do not interfere with each other and the imaging device 100 can be miniaturized. Also, since the VCSEL substrates 22F and 22B are configured with the minimum quantity that can be projected onto the entire sphere which is the measurement range of the object, the imaging device 100 can be miniaturized.

[0053] Next, the CMOS light receiving unit 30 will be described. Here, FIG. 8 is a diagram showing a cross section of the CMOS light receiving unit 30.

[0054] As shown in FIG. 8, the CMOS light receiving unit 30 includes a CMOS optical system 31, a CMOS sensor substrate 32, and a lens holder 34.

[0055] The CMOS optical system 31 is composed of a plurality of lenses, prisms, etc. The CMOS sensor substrate 32 mounts the CMOS sensor 33. The lens holder 34 integrally holds the CMOS optical system 31 and the CMOS sensor substrate 32. The CMOS substrate 32 is fixed to the holding portion 34a of the lens holder 34 by a method such as adhesion.

[0056] The imaging device 100 causes scattered light emitted from external illumination or the VCSEL light projecting unit 21 and reflected by an external object to enter the CMOS optical system 31 as shown by the arrow in Fig. 8, and the CMOS sensor 33 receives the light. When a white light source is used for external illumination, the CMOS sensor 33 can capture a luminance image or an RGB image according to the intensity of the scattered light reflected by the external object. When the scattered light reflected by the object from the light emitted by the VCSEL light projecting unit 21 enters the CMOS optical system 31, the CMOS sensor 33 can capture a luminance image at the wavelength of the light emitted by the VCSEL light projecting unit 21.

[0057] Here, Fig. 9-1 is a diagram showing the connection by the CMOS substrates 35 of two CMOS light receiving units 30, and Fig. 9-2 is a diagram showing the arrangement of the CMOS substrates 35.

[0058] As shown in Fig. 9-1, the imaging device 100 arranges the optical axis of the CMOS optical system 31 in a direction parallel to the Y-axis direction. Also, the imaging device 100 arranges two CMOS optical systems 31 (CMOS light receiving units 30R, 30L), which are a plurality of imaging units, in opposite directions to each other. The imaging device 100 connects the CMOS sensor substrates 32 of the CMOS light receiving units 30R, 30L to a common (one) CMOS substrate 35 with a cable such as an FPC.

[0059] As shown in Fig. 9-2, the imaging device 100 screws the CMOS substrate 35 onto the bracket member 36L screwed to the left cover 13, the bracket member 36R screwed to the right cover 14 (not shown), and the bracket member 36C fastened to the inner wall 10 via a spacer member 37.

[0060] The CMOS optical system 31 has the function of a fish-eye lens. In a situation where light rays are blocked by surrounding components or the like, the CMOS optical system 31 can receive scattered light from the area of the entire sphere (4π [sr]) by the two CMOS light-receiving units 30R and 30L.

[0061] Next, the arrangement of the CMOS light-receiving unit 30 will be described. Here, FIG. 10 is a diagram showing an arrangement example of the CMOS light-receiving unit 30 and the VCSEL light-projecting unit 21.

[0062] As shown in FIGS. 1-2 and 10, the imaging device 100 arranges a part (or the whole) of the CMOS light-receiving unit 30 (lens holder 34) between the two VCSEL substrates 22F and 22B. Thereby, the imaging device 100 can reduce the size in the incident optical axis direction (Y-axis direction) of the CMOS optical system 31.

[0063] As shown in FIG. 10, the imaging device 100 fixes the CMOS light-receiving units 30R and 30L respectively by fastening the screws 66b to the right cover 14 and the left cover 13. When fastening with screws, the positioning parts provided on the lens holders 34 of the CMOS light-receiving units 30R and 30L are positioned corresponding to the positioning parts on the right cover 14 and the left cover 13 sides. Thereby, the alignment accuracy of the CMOS light-receiving unit 30R with respect to the right cover 14 and the alignment accuracy of the CMOS light-receiving unit 30L with respect to the left cover 13 can be maintained.

[0064] Next, the TOF light-receiving unit 61 will be described. Here, FIG. 11-1 is an external perspective view showing the TOF light-receiving unit 61, FIG. 11-2 is a perspective view showing the internal configuration of the TOF light-receiving unit 61, and FIG. 11-3 is a diagram showing a partially cut-away internal configuration of the TOF light-receiving unit 61.

[0065] As shown in FIGS. 11-1 to 11-3, the TOF light receiving unit 61 has a four-eye configuration. The TOF light receiving unit 61 includes a TOF optical system 71 (71A, 71B, 71C, 71D), which is a plurality of light receiving units that receive the range to be measured (entire celestial sphere), a TOF sensor substrate 74, a relay substrate 77, and a holder member 78.

[0066] The TOF sensor substrate 74 mounts a TOF sensor 76.

[0067] The relay substrate 77 serves as a relay part between the TOF sensor substrate 74 and the main substrate 41.

[0068] The holder member 78 integrally holds the TOF optical system 71 (71A, 71B, 71C, 71D) and the TOF sensor substrate 74.

[0069] Note that the TOF sensor substrate 74 and the relay substrate 77, and the relay substrate 77 and the main substrate 41 are connected by a cable such as an FPC.

[0070] As shown in FIGS. 11-1 to 11-3, since the imaging device 100 has the TOF light receiving unit 61 in an integrated structure, it is possible to simplify the equipment for assembly / adjustment in the factory, shorten the assembly / adjustment time, and perform quality assurance in the integrated structure. Further, since the imaging device 100 has the TOF light receiving unit 61 in an integrated structure, it can be mounted not only on one model but also on a plurality of models, so that cost reduction is also possible.

[0071] The imaging device 100 receives the light (scattered light) emitted from the VCSEL light projecting unit 21 and reflected by an external object via the TOF optical system 71 with the TOF sensor 76 mounted on the TOF sensor substrate 74.

[0072] Here, FIGS. 12-1 and 12-2 are diagrams showing the respective arrangement relationships of the TOF optical system 71.

[0073] As shown in FIGS. 12-1 and 12-2, the TOF optical system 71A is arranged such that its incident optical axis faces upward (+X). The incident optical axes of the TOF optical systems 71B, 71C, and 71D face the horizontal direction, and the incident optical axis of the TOF light receiving system 71B faces rightward (+Y). The TOF optical systems 71C and 71D are arranged at an angle rotated 120° around the X-axis with respect to the TOF optical system 71B.

[0074] The field of view angle (vertical direction; X-Y cross-section and X-Z cross-section) of the TOF optical system 71A arranged in the vertical direction is 65°. The field of view angle of the TOF optical system 71B arranged in the horizontal direction (rightward) is 85° in the vertical direction (X-Y cross-section) and 65° in the horizontal direction (Y-Z cross-section). The TOF optical systems 71C and 71D are the same as the TOF optical system 71B. With such an arrangement, the imaging device 100 can receive the reflected light (scattered light) from objects in all directions by the TOF light receiving unit 61 with a four-eye configuration, except for the area with a field of view angle of 85° or more on the lower side.

[0075] The field of view angle of the TOF optical system 71 (TOF optical systems 71A, 71B, 71C, 71D) is configured to be narrower than the field of view angle of the VCSEL optical system 23, so the focal length of the TOF optical system 71 becomes longer. Therefore, the TOF optical system 71 can increase the amount of received light per unit field of view angle, which is related to the amount of received light per unit pixel of the TOF sensor 76. Thereby, the TOF optical system 71 can increase the amount of received light of the light reflected by a distant object or an object with low reflectivity.

[0076] Next, the relative positional relationship between the VCSEL light projecting unit 21 and the TOF light receiving unit 61 will be described. Here, FIG. 13 is a plan view showing the VCSEL light projecting unit 21 and the TOF light receiving unit 61, FIG. 14 is a diagram showing the positional relationship between the VCSEL optical system 23 and the TOF optical system 71, and FIG. 15 is a diagram showing a comparative example of the positional relationship between the VCSEL optical system 23 and the TOF optical system 71. FIG. 14 is extracted from the plan view of the configuration of the imaging device 100 of the present embodiment shown in FIG. 13, showing only the outermost lenses in the VCSEL light projecting unit 21 and the TOF light receiving unit 61. Also, the configuration of the comparative example of the present embodiment is shown in FIG. 15.

[0077] The comparative example shown in FIG. 15 shows the arrangement when the TOF optical systems 71B, 71C, and 71D are rotated 30° about the X-axis. In the comparative example shown in FIG. 15, the VCSEL optical system 23F and the TOF optical system 71D are arranged so as to face the same direction (+Z direction). Therefore, in the imaging device with the arrangement of the comparative example shown in FIG. 15, most of the light amount of the scattered light emitted from the VCSEL optical system 23F arranged on the +Z side and reflected by the object is received by the TOF optical system 71D.

[0078] Also, the imaging device with the arrangement of the comparative example shown in FIG. 15 receives half of the light amount of the scattered light emitted from the VCSEL optical system 23B arranged on the -Z side and reflected by the object with the TOF optical system 71B, and the remaining half with the TOF optical system 71C. As a result, in the imaging device with the arrangement of the comparative example shown in FIG. 15, large deviations are likely to occur in the light amounts received by the three TOF light receiving units 71B, 71C, and 71D (the light amount ratio is generally 71B:71C:71D = 0.5:0.5:1), and the detection accuracy is likely to decrease.

[0079] On the other hand, as shown in FIG. 14, the imaging device 100 arranges the VCSEL optical systems 23F and 23B symmetrically with respect to the X-Y plane, and arranges the TOF optical systems 71B, 71C, and 71D symmetrically with respect to the X-Y plane. Therefore, the imaging device 100 can reduce the deviation in the light amounts received by the three TOF optical systems 71B, 71C, and 71D (the deviation between the three TOF optical systems) as compared with the comparative example shown in FIG. 15. As a result, the imaging device 100 can achieve higher detection accuracy.

[0080] Next, the angular field of view of the VCSEL optical system 23 will be described. FIG. 16 is a diagram showing the angular field of view of the VCSEL optical system 23.

[0081] As shown in FIG. 16, the imaging device 100 arranges the TOF optical system 71A in the TOF light receiving unit 61 at the first stage from the upper side (+X side), and arranges the TOF optical systems 71B, 71C, and 71D at the second stage. The imaging device 100 arranges the VCSEL optical systems 23F and 23B, and the CMOS optical systems 31R and 31L at the third stage.

[0082] FIG. 16 schematically shows the outermost marginal light rays of the VCSEL optical system 23F and the TOF optical systems 71A and 71B in the vertical cross-section (Z-X cross-section). In FIG. 16, in order to avoid complicated explanations, the TOF optical systems 71B, 71C, and 71D are rotated around the X axis so that the incident optical axis of the TOF optical system 71B is parallel to the Z axis. In the following description, it is assumed that the TOF optical systems 71A to 71D and 171A to 171D are designed to have a wider angle of view than the optical systems shown in FIG. 12-2 (maximum angle of view: 90°).

[0083] As shown in FIG. 16, since the outermost marginal angle of view of the irradiable range above the VCSEL optical system 23F on the +Z side of the imaging device 100 is θvcsel2>90°, combined with the light projection (irradiation light) by the VCSEL optical system 23B on the back side (-Z side), the irradiable range of the VCSEL light projection unit 21 can cover the area of a hemisphere (2π[sr]).

[0084] The light-receivable range above the TOF light receiving unit 61 can cover the area of a hemisphere from the light-receivable range (angle of view θtof1) of the upward TOF optical system 71A and the light-receivable ranges (angle of view θtof2) of the horizontal TOF optical systems 71B (and 71C and 71D). Therefore, the imaging device 100 can comprehensively photograph the photographable range of the upper hemisphere. Note that the "photographable range" by the CMOS light receiving unit 30 is the area where the "irradiable range by the VCSEL light projection unit 21" and the "light-receivable range by the CMOS light receiving unit 30" overlap.

[0085] Next, the hardware configuration of the imaging device 100 will be described. Here, the hardware configuration related to distance measurement from the imaging device 100 to the subject will be described.

[0086] FIG. 17 is a block diagram showing an example of the hardware configuration of the imaging device 100. In FIG. 17, the imaging device 100 includes a VCSEL light projecting unit 21, a TOF light receiving unit 61, a CMOS light receiving unit 30, and a distance measurement control unit 230.

[0087] The distance measurement control unit 230 is connected to the VCSEL light projecting unit 21, the TOF light receiving unit 61, and the CMOS light receiving unit 30 and is built into the cover member. The distance measurement control unit 230 includes a CPU (Central Processing Unit) 231, a ROM (Read Only Memory) 232, a RAM (Random Access Memory) 233, an SSD (Solid State Drive) 234, a light source drive circuit 235, a sensor I / F (Interface) 236, an input / output I / F 237, and an RGB sensor I / F 240. These are electrically connected to each other by a system bus 242.

[0088] The CPU 231 reads programs and data from storage devices such as the ROM 232 and the SSD 234 onto the RAM 233 and executes processing to realize the overall control of the distance measurement control unit 230 and the functions described later. Note that some or all of the functions of the CPU 231 may be realized by an electronic circuit such as an ASIC (application specific integrated circuit) or an FPGA (Field-Programmable Gate Array).

[0089] The ROM 232 is a non-volatile semiconductor memory (storage device) that can hold programs and data even when the power is turned off. Programs and data such as the BIOS (Basic Input / Output System) and OS settings that are executed when the imaging device 100 is started are stored in the ROM 232.

[0090] The RAM 233 is a volatile semiconductor memory (storage device) that temporarily holds programs and data.

[0091] The SSD 234 is a non-volatile memory in which programs and various data for executing processing by the distance measurement control unit 230 are stored. Note that the SSD may be an HDD (Hard Disk Drive) or the like.

[0092] The light source drive circuit 235 is an electric circuit that is electrically connected to the VCSEL light projecting unit 21 and outputs a drive signal such as a drive voltage to the VCSEL light projecting unit 21 according to a control signal input from the CPU 231 or the like. The light source drive circuit 235 causes a plurality of light emitting units included in the VCSEL light projecting unit 21 to emit light according to the control signal. As the drive signal, a rectangular wave, a sine wave, or a voltage waveform having a predetermined waveform shape can be used. Note that the light source drive circuit 235 can modulate the frequency of the drive signal by changing the frequency of the voltage waveform.

[0093] The sensor I / F 236 is an interface that is electrically connected to the TOF light receiving unit 61 and inputs the phase signal output by the TOF light receiving unit 61. The input / output I / F 237 is an interface for connecting to an external device such as a PC (Personal Computer).

[0094] The RGB sensor I / F 240 is an interface that is electrically connected to the CMOS light receiving unit 30 and inputs the RGB signal output by the CMOS light receiving unit 30.

[0095] FIG. 18 is a functional block diagram for explaining the functions of the imaging device 100. In FIG. 18, as a function of the imaging device 100, a distance measurement control unit 230 is provided.

[0096] The distance measurement control unit 230 includes a light emission control unit 238, a light reception processing unit 239, and an RGB image processing unit 241. The distance measurement control unit 230 controls the synchronization of the light emission by the VCSEL light projection unit 21 via the light emission control unit 238, the light reception by the TOF light reception unit 61 via the light reception processing unit 239, and the light reception by the CMOS light reception unit 30 via the RGB image processing unit 241, so as to acquire a distance image and an RGB image at the same timing.

[0097] The light emission control unit 238 includes at least a drive signal output unit 238a as a function of the imaging device 100.

[0098] The drive signal output unit 238a outputs a drive signal to the VCSEL light projection unit 21 to cause simultaneous light emission. Further, the drive signal output unit 238a can time-modulate (temporally control) the light emission by the VCSEL light projection unit 21 by outputting a drive signal with a predetermined voltage waveform and a predetermined light emission frequency. In the present embodiment, as an example, a drive signal in the form of a rectangular wave or a sine wave at a frequency of about MHz is output to the VCSEL light projection unit 21 at a predetermined timing.

[0099] The light reception processing unit 239 includes at least a phase signal input unit 239a, a distance image acquisition unit 239b, a storage unit 239c, and a distance image combining unit 239d as functions of the imaging device 100.

[0100] The phase signal input unit 239a is realized by the sensor I / F 236 or the like and inputs the phase signal output by the TOF light reception unit 61. The phase signal input unit 239a can input the phase signal for each pixel arranged two-dimensionally in the TOF light reception unit 61. Further, the phase signal input unit 239a outputs the input phase signal to the distance image acquisition unit 239b. In the present embodiment, the TOF light reception unit 61 is connected to the phase signal input unit 239a. For this reason, phase signals corresponding to four sets corresponding to the TOF optical system 71 (71A, 71B, 71C, 71D) are output.

[0101] The distance image acquisition unit 239b acquires distance image data from the imaging device 100 to the object based on the phase signals for each pixel of the TOF light receiving unit 61 input from the phase signal input unit 239a. Here, the distance image is an image generated by two-dimensionally arranging the distance data acquired for each pixel according to the position of the pixel. For example, it is an image generated by converting the distance into the luminance of the pixel. The distance image acquisition unit 239b outputs the four acquired distance image data to the storage unit 239c.

[0102] The storage unit 239c is realized by the RAM 233 or the like and temporarily stores the distance image data input from the distance image acquisition unit 239b.

[0103] The distance image combining unit 239d reads out the four distance image data temporarily stored in the storage unit 239c, combines them, and generates one omnidirectional distance image data.

[0104] Note that the distance image combining unit 239d is realized by the CPU 231 executing a control program. However, it is not limited to this example, and part or all of the distance image combining unit 239d may be realized by dedicated hardware designed to execute similar functions, such as semiconductor integrated circuits such as ASIC (Application Specific Integrated Circuit), DSP (digital signal processor), FPGA (field programmable gate array), or conventional circuit modules.

[0105] The RGB image processing unit 241 includes an RGB image input unit 241a, an RGB image storage unit 241b, and an RGB image combining unit 241c.

[0106] The RGB image input unit 241a inputs the RGB image output by the CMOS light receiving unit 30. For example, the RGB image input unit 241a can input the RGB signals for each pixel arranged two-dimensionally in the CMOS light receiving unit 30. The RGB image input unit 241a outputs the input RGB image to the RGB image storage unit 241b. (In this embodiment, since two CMOS light receiving units 30R and 30L are connected to the RGB image processing unit 241, two RGB images are output.) Note that the RGB image input unit 241a is realized by the RGB sensor I / F 240 or the like.

[0107] The RGB image storage unit 241b is realized by the RAM 233 or the like and temporarily stores the RGB image data input from the RGB image input unit 241a.

[0108] The RGB image combining unit 241c reads out the two RGB image data temporarily stored in the RGB image storage unit 241b, combines them, and generates one omnidirectional RGB image data. Note that the RGB image combining unit 241c is realized by the CPU 231 executing a control program. However, it is not limited to this example, and part or all of the RGB image combining unit 241c may be realized by dedicated hardware designed to execute similar functions, such as semiconductor integrated circuits such as ASIC (Application Specific Integrated Circuit), DSP (Digital Signal Processor), FPGA (Field Programmable Gate Array), or conventional circuit modules.

[0109] In the above description, the configuration shown in FIG. 18 has been described as being built into the imaging device 100, but this is not limited to this example. For example, the configuration shown in FIG. 18 may be provided in an external information processing device that can be connected to the imaging device 100.

[0110] According to this embodiment, since the number of light projecting units (VCSEL light projecting units 21F and 21B) is made smaller than the number of light receiving units (TOF optical systems 71A, 71B, 71C, and 71D) to cover the measurement target range, the light source of the light projecting unit can be made larger to increase the intensity of the irradiated light. Therefore, even for distant objects or low-reflectivity objects, a sufficient amount of received light can be obtained, and the measurement accuracy can be improved. Also, according to this embodiment, since the number of light receiving units is made larger than the number of light projecting units to cover the measurement target range, the angular field of view of one light receiving unit can be set narrow. As a result, the focal length of the light receiving unit can be increased, the F value of the lens of the light receiving unit can be made larger, and the ranging accuracy for distant objects can be improved. That is, according to this embodiment, by making the number of light receiving units larger than the number of light projecting units, with a limited device size, the intensity of the light projected by the light projecting unit can be increased, the focal length of the light receiving unit can be increased, and the ranging accuracy can be improved.

[0111] (Second Embodiment) Next, the second embodiment will be described.

[0112] The second embodiment is different from the first embodiment in that the TOF light receiving unit is divided into upper and lower two stages, and a VCSEL light projecting unit and a CMOS light receiving unit are arranged between them. Hereinafter, in the description of the second embodiment, the description of the same parts as those of the first embodiment will be omitted, and the parts different from those of the first embodiment will be described.

[0113] By the way, as shown in FIG. 16, in order for the imaging device 100 to secure an irradiable range of the upper half sphere (2π [sr]) by the emitted light of the VCSEL light projecting unit 21, it is necessary to arrange the position of the outermost lens of the VCSEL optical system 23F to be on the right side (+Z side) rather than the position of the outermost lens of the TOF optical system 71B. As a result, inevitably E1 > D1, and the dimension of the imaging device 100 in the Z-axis direction tends to be large.

[0114] Further, as shown in FIG. 16, the imaging device 100 needs to prevent the incident light rays within the viewing angle θtof3 below the TOF optical system 71B from being blocked by the VCSEL optical system 23F. Therefore, θtof3 is about 60° or less, and the dead angle A is likely to become large. As a result, even when the viewing angle (irradiable range) below the VCSEL optical system 23F is set to θvcsel2 > 90°, the imaging range is defined by the dead angle A below the TOF optical system 71B. Therefore, the imaging device 100 may not be able to capture the entire lower hemisphere.

[0115] Here, FIG. 19 is a diagram showing an enlarged view of a part of the optical system of the imaging device 200 according to the second embodiment.

[0116] As shown in FIG. 19, in the imaging device 200 of the present embodiment, the TOF light receiving unit is divided into upper and lower two stages, and the VCSEL light projecting unit (VCSEL optical systems 23F and 23B) and the CMOS light receiving unit (CMOS optical systems 31R and 31L) are arranged between them. More specifically, the imaging device 200 arranges the TOF optical system 71A in the first stage, arranges the TOF optical systems 71B, 71C, and 71D in the third stage, and arranges the VCSEL optical systems 23F and 23B and the CMOS optical systems 31R and 31L between them (the second stage).

[0117] The imaging device 200 receives the light (scattered light) emitted from the VCSEL optical systems 23F and 23B and reflected by an external object through the TOF optical systems 71A to 71D with TOF sensors mounted on the TOF sensor substrates 74A to 74D, respectively.

[0118] FIG. 20 is a diagram showing the viewing angle of the VCSEL optical system 123. FIG. 20 schematically shows the outermost peripheral viewing angle light rays in the vertical cross-section (Z-X cross-section) of the VCSEL optical system 23F and the TOF optical systems 71A and 71B. In FIG. 20, the TOF optical systems 71B, 71C, and 71D are rotated around the X-axis so that the incident optical axis of the TOF optical system 71B is parallel to the Z-axis.

[0119] As shown in FIG. 20, the imaging device 200 can secure a hemispherical (2π [sr]) region by making the outermost field angle Ωvcsel2 of the irradiable range above the VCSEL light projecting units (VCSEL optical systems 23F and 23B) larger than 90°. Further, the imaging device 200 can cover a hemispherical region (2π [sr]) as the light-receivable range above the entire TOF light-receiving unit by the light-receivable range (field angle Ωtof2) above the TOF optical system 71B (and 71C and 71D) and the light-receivable range (field angle Ωtof1) of the TOF optical system 171A. Therefore, the imaging device 200 can comprehensively photograph the photographable range of the upper hemispherical region.

[0120] In the imaging device 200 of the present embodiment, only the TOF optical system 71A is arranged above the VCSEL optical system 23F (second stage) (first stage). Therefore, unlike the imaging device 100 of the first embodiment, D2 = E2 can be set, there is no need to expand the dimension in the Z-axis direction, and miniaturization is possible.

[0121] Also, as shown in FIG. 20, the imaging device 200 can expand the outermost field angle Ωvcsel2 below the VCSEL optical system 23F to such an extent that it cannot be detected by the TOF light-receiving system 71B (Ωvcsel2 ≤ about 85°).

[0122] On the other hand, the imaging device 200 can secure up to 90° in the Z-X cross section for the light-receivable range of the TOF light-receiving unit by the light-receivable range (field angle Ωtof3) below the TOF optical system 71B. Therefore, the imaging device 200 can almost comprehensively photograph the photographable range of the lower hemispherical region by including the light-receivable ranges of the TOF optical systems 71C and 71D.

[0123] Thus, according to the present embodiment, the photographable range can be almost comprehensively photographed.

[0124] In each of the embodiments, a distance measurement device (imaging devices 100 and 200) that integrally includes VCSEL light projection units 21F and 21B which are a plurality of light projection units, TOF optical systems 71 (71A, 71B, 71C, 71D) which are a plurality of light reception units, CMOS light reception units 30R and 30L which are a plurality of imaging units, and a distance measurement control unit 230 that performs distance measurement calculation has been described. However, the present invention is not limited to this. For example, a light projection unit having VCSEL light projection units 21F and 21B which are a plurality of light projection units, a TOF light reception unit having TOF optical systems 71 (71A, 71B, 71C, 71D) which are a plurality of light reception units, a CMOS imaging unit having CMOS light reception units 30R and 30L which are a plurality of imaging units, and a distance measurement control unit 230 that performs distance measurement calculation may be configured as separate devices, and a distance measurement system in which these devices are interconnected by a network or the like may be applied.

[0125] Note that each of the above-described embodiments is a preferred example of the present invention, but the present invention is not limited thereto, and various modifications can be made without departing from the gist of the present invention.

Explanation of Reference Numerals

[0126] 21F, 21B Light projection units 30R, 30L Imaging units 71A, 71B, 71C, 71D Light reception units 100, 200 Distance measurement devices 230 Distance measurement control unit

Prior Art Documents

Patent Documents

[0127]

Patent Document 1

Claims

**Claim 1**: A plurality of light projecting units, each having a partial overlapping field angle and irradiating light onto a measurement target range; A plurality of light receiving units, each having a partial overlapping field angle and receiving light reflected by an object within the measurement target range; A distance measurement control unit including a light emission control unit for controlling the light emission of the plurality of light projecting units and a light reception processing unit for controlling the light reception of the plurality of light receiving units; Comprising: The number of the plurality of light receiving units is greater than the number of the plurality of light projecting units; Each of the plurality of light receiving units faces a direction different from any of the plurality of light projecting units; The plurality of light receiving units include a first light receiving unit facing a first direction and a plurality of second light receiving units facing directions different from the first direction; The first light receiving unit, the plurality of second light receiving units, and the plurality of light projecting units are sequentially arranged from one end side of the housing; A distance measurement device, characterized in that. **Claim 2** The field angle of each of the plurality of light receiving units is narrower than the irradiation range of each of the plurality of light projecting units; The distance measurement device according to claim 1, characterized in that. **Claim 3** Among the plurality of light receiving units, the optical axis of at least one light receiving unit is perpendicular to the optical axes of at least two other light receiving units; The optical axes of the plurality of light projecting units are perpendicular to the optical axis of the at least one light receiving unit; The distance measurement device according to claim 1 or 2, characterized in that. **Claim 4** Comprising a plurality of imaging units for imaging the measurement target range; The distance measurement device according to any one of claims 1 to 3, characterized in that. **Claim 5** Comprising a plurality of imaging units for imaging the measurement target range; The number of the plurality of imaging units is less than the number of the plurality of light receiving units; The optical axes of the plurality of imaging units are perpendicular to the optical axis of the at least one light receiving unit; The distance measurement device according to claim 3, characterized in that. **Claim 6** Each of the plurality of light receiving units receives the light from at least two of the light projecting units; The distance measurement device according to any one of claims 1 to 5, characterized in that. **Claim 7** The measurement target range is a range of the entire celestial sphere that can be irradiated with light by the plurality of light projecting units; The distance measurement device according to any one of claims 1 to 6, characterized in that. **Claim 8**: A light projecting unit having a plurality of light projecting units, each having a partial overlapping field angle and irradiating light onto a measurement target range; A light receiving unit having a plurality of light receiving units, each having a partial overlapping field angle and receiving light reflected by an object within the measurement target range; A ranging control unit including a light emission control unit that controls light emission of the plurality of light projection units and a light reception processing unit that controls light reception of the plurality of light reception units, comprising, the number of the plurality of light reception units is larger than the number of the plurality of light projection units, each of the plurality of light reception units faces a direction different from any of the plurality of light projection units, the plurality of light reception units include a first light reception unit facing a first direction and a plurality of second light reception units facing directions different from the first direction, the first light reception unit, the plurality of second light reception units, and the plurality of light projection units are sequentially arranged from one end side of the housing, a ranging system characterized by this.

9. comprising an imaging unit having a plurality of imaging units that image a range of the measurement target, the ranging system according to claim 8, characterized by this.

Images