Distance imaging device

Abstract

To provide a distance image acquisition device that ensures internal watertightness while enabling efficient heat dissipation. [Solution] The distance image acquisition device comprises an imaging unit having a VCSEL 42, an optical unit, and an image sensor, a main board for controlling the imaging unit, and a metal housing 10 in which the imaging unit and the main board are housed. The imaging unit has a light source substrate 41 on which the VCSEL 42 is attached, an element substrate 55 on which the image sensor is attached, and a metal support block 60 which is thermally connected to the housing and supports the optical unit from below, with the light source substrate and the element substrate being thermally connected to the support block.

Description

Technical Field

[0001] The present invention relates to a distance image capturing device.

Background Art

[0002] An imaging device provided with a light source is known. A typical use of the light source is a flash used for photographing in a dark place. A distance image capturing device, which is a type of imaging device, acquires a distance image based on reflected light obtained by reflecting reference light irradiated from a light source by an object, by an image sensor, and measures the distance to the object by a predetermined process such as a time-of-flight (TOF) method or the like.

[0003] The light source generates heat during light emission and becomes high temperature. Further, in the imaging device, the image sensor also generates heat during driving. If the inside becomes too high temperature due to this heat generation, it may cause abnormal operation. Regarding this problem, Patent Document 1 describes an imaging device including a duct having a first air intake through which outside air can flow in, and a centrifugal fan that forcibly causes outside air to flow into the duct from the first air intake. By forcibly causing outside air to flow into the duct thermally connected to the heat generating body using the centrifugal fan, efficient heat dissipation is enabled.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Since a distance image capturing device is often installed in a harsh environment such as inside a factory, it is required to ensure internal waterproofness. Therefore, it is difficult to apply the technology of Patent Document 1 that essentially requires an air intake. On the other hand, as will be explained in more detail later, there are other situations in which depth image acquisition devices tend to become hot, so more efficient heat dissipation is required compared to general imaging devices equipped with a flash light source.

[0006] Based on the above circumstances, the present invention aims to provide a distance image acquisition device that can efficiently dissipate heat while ensuring internal watertightness. [Means for solving the problem]

[0007] The present invention relates to a distance image acquisition device comprising an imaging unit having a light source, an optical unit, and an image sensor; a main board for controlling the imaging unit; and a metal housing in which the imaging unit and the main board are housed. The imaging unit comprises a light source substrate to which a light source is attached, an element substrate to which an image sensor is attached, and a metal support block that is thermally connected to the housing and supports the optical unit from below. The light source substrate and the element substrate are thermally connected to the support block. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a distance image acquisition device that can efficiently dissipate heat while ensuring internal watertightness. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view showing a camera related to one embodiment of the present invention. [Figure 2] This is a schematic diagram showing the general configuration of the camera. [Figure 3] This is a diagram showing the camera disassembled. [Figure 4] This diagram shows the imaging unit of the camera disassembled. [Figure 5] This is a view of the light source substrate of the imaging unit from the rear. [Figure 6] This figure shows the imaging unit in one cross-section. [Figure 7] This figure shows the same imaging unit in a different cross-section than that shown in Figure 6. [Figure 8] This figure shows a modified example of the element substrate related to the imaging unit. [Modes for carrying out the invention]

[0010] One embodiment of the present invention will be described with reference to Figures 1 to 7. Figure 1 is a perspective view showing a camera 1, which is a distance image acquisition device according to this embodiment. The camera 1 has a rectangular parallelepiped shape defined by a metal housing 10. The housing 10 has a first aperture 2 for imaging and a second aperture 3 for a light source that emits reference light on its front. Two second apertures 3 are provided so as to sandwich the first aperture 2.

[0011] Figure 2 shows a schematic diagram of the camera 1's configuration. Inside the housing 10 are the power supply board 20, the main board 30, and the imaging unit 40. The power supply board 20 is connected to the power supply Es and generates voltages to drive the various parts of the camera 1. The main board 30 is composed of integrated circuits and is connected to the power supply board 20 and the imaging unit 40. The main board 30 controls the operation of the power supply board 20 and the imaging unit 40, and performs correction processing of the data handled by the imaging unit 40. A hub 31 used for connecting to the power supply Es and an external computer 200 is connected to the main board 30. There are no particular restrictions on the integrated circuits included in the main board 30, and FPGAs (Field-Programmable Gate Arrays), ASICs (Application Specific Integrated Circuits), CPUs, etc., can be selected and used as appropriate.

[0012] Figure 3 shows the camera 1 in an exploded view. The housing 10 has a main body 11 with an internal space and a lid 12. The power supply board 20, main board 30, and imaging unit 40 are arranged inside the main body 11, and the lid 12 is screwed to the main body 11, sealing them within the housing 10. A rubber gasket 13 is placed between the main body 11 and the lid 12, ensuring waterproofing inside the housing 10 when the lid 12 and hub 31 are attached. A light-shielding cover 4 is attached to the first opening 2 and the second opening 3, and is configured such that natural light or the like that is not used for obtaining a distance image (described later) hardly enters the housing 10.

[0013] Fig. 4 shows the imaging unit 40 disassembled. The imaging unit 40 includes a light source substrate 41 to which a light source is attached, and an optical unit 50 including a lens and an imaging element. The imaging unit 40 of the present embodiment uses two vertical cavity surface emitting lasers (VCSELs) as light sources, and two VCSELs 42 are attached to the light source substrate 41. The VCSEL 42 is an example, and of course, other light sources can also be used. The optical unit 50 includes a lens barrel 51 to which a lens 52 is attached, a lens holder 53 to which the lens barrel 51 is fixed, and an element substrate 55 on which an imaging element 56 is mounted. As the imaging element 56, for example, a CMOS image sensor can be used, and it is attached to the surface of the element substrate 55 facing the first opening 2. Further, the imaging element 56 is covered by a sensor cover 61 to which a band-pass filter is attached, and the light incident on the imaging element 56 through the lens 52 reaches the imaging element 56 after passing through the band-pass filter. In the camera 1, the lens holder 53 is fixed to the sensor cover 61, so that the lens 52 is aligned with the imaging element 56.

[0014] A metal support block 60 is disposed around the lens 52 and the lens holder 53 between the light source substrate 41 and the element substrate 55. The support block 60 is in contact with the light source substrate 41 and the element substrate 55, and is configured such that heat generated by the VCSEL 42 and the imaging element 56 during driving is released to the outside of the housing 10 via the support block 60.

[0015] The camera 1 acquires a distance image based on the reflected light reflected by the target object from the reference light irradiated from the VCSEL 42 serving as the light source by the imaging element 56, and measures the distance to the object by the time-of-flight (TOF) method.

[0016] In a distance imaging device, a VCSEL 42 or the like used as a light source for reference light becomes much hotter during driving than a light source used for a flash or the like. Furthermore, since the driver IC for controlling the VCSEL 42 also generates heat during driving, if this heat is not appropriately released outside the camera 1, the temperature inside the housing 10 easily exceeds 100°C, increasing the likelihood of adversely affecting the operation of the camera 1. To suppress this, the camera 1 employs a heat dissipation mechanism using a metal support block 60. This will be described in detail below.

[0017] FIG. 5 is a view of the light source substrate 41 seen from the rear side. On the back surface, two first heat dissipation pads 46 for dissipating heat from the VCSEL 42 are formed corresponding to each VCSEL 42 at positions corresponding to directly behind the VCSEL 42. The VCSEL 42 and the corresponding first heat dissipation pad 46 are thermally connected by a plurality of thermal wirings 47 (see FIG. 6) that penetrate the light source substrate 41 back and forth. The thermal wiring 47 of the present embodiment is a through-hole, but a conductor layer may be formed on the inner surface or the conductor may be filled. The size of the first heat dissipation pad 46 can be, for example, a square with a side length of 3 mm. On the upper side of the first heat dissipation pad 46, two second heat dissipation pads 48 for dissipating heat from the driver IC 43 are formed corresponding to each driver IC 43. The driver IC 43 and the corresponding second heat dissipation pad 48 are thermally connected by a thermal wiring (not shown) that penetrates the light source substrate 41. In the present embodiment, the first heat dissipation pad 46, the second heat dissipation pad 48, and each of the above wirings are all made of copper, but may be formed of other materials with excellent thermal conductivity such as aluminum. On the front surface of the light source substrate 41, as shown in FIG. 4, driver ICs 43 corresponding to each of the two VCSEL 42s are attached. The driver IC 43 may be arranged on the back surface of the light source substrate 41.

[0018] The support block 60 according to this embodiment is made of die-cast aluminum, taking thermal conductivity into consideration. As shown in Figure 4, the support block 60 has a space in the center in the left-right direction for arranging the optical unit 50, and on both the left and right sides of this space there are heat dissipation sections 71 which are fixed to the housing 10. Each heat dissipation section 71 is located behind the first heat dissipation pad 46 and the second heat dissipation pad 48, and has a vertical hole 72 for fixing the support block 60 to the main body 11 of the housing 10.

[0019] Figure 6 shows a cross-sectional view of the imaging unit 40 passing through the vertical hole 72. The vertical hole 72 has a lower first region 72a and an upper second region 72b, and a partition 73 with a through hole is provided between the first region 72a and the second region 72b. The columnar portion 11a of the main body 11 enters the first region 72a. The support block 60 and the main body 11 are fixed to each other by a screw 76 located in the second region 72b that engages with the columnar portion 11a beyond the partition 73. At the same time, the inner circumferential surface of the first region 72a and the outer circumferential surface of the columnar portion 11a come into contact, so that the two are thermally connected even in parts other than the lower surface of the support block 60.

[0020] The first heat dissipation pad 46 and the second heat dissipation pad 48 are thermally connected to the front surface of the heat dissipation section 71 with a heat dissipation sheet 75 in between. There are no restrictions on the material of the heat dissipation sheet 75, and any known material can be appropriately selected and used, but suitable examples include silicone, acrylic resin, graphite, etc.

[0021] The back surface of the heat dissipation section 71 is in contact with the element substrate 55 located around the image sensor 56. On the element substrate 55, an L-shaped heat sink 81 is thermally connected to the back surface opposite to the heat dissipation section 71. On the element substrate 55, the part to which the heat sink 81 is connected is located directly behind the image sensor 56, and in a front view of the element substrate 55 from the first aperture 2 side, at least a portion of the image sensor 56 and the heat sink 81 overlap. One end of the heat sink 81 is fixed to the main body 11 of the housing 10 by screwing it in. The heat sink 81 is preferably made of a metal with good thermal conductivity, such as aluminum. In this embodiment, the housing 10, including the main body 11, is also made of aluminum.

[0022] Figure 7 shows a cross-sectional view of the imaging unit 40 passing through the image sensor 56. A heat dissipation pad 57 is provided on the back surface of the element substrate 55, in the area directly behind the image sensor 56. The image sensor 56 and the heat dissipation pad 57 are thermally connected by columnar thermal wiring 58 made of conductors arranged to fill the through-holes in the element substrate 55. Since there is more space on the back side of the element substrate 55 compared to the back side of the light source substrate 41, the radial dimension of the thermal wiring 58 is larger than that of the thermal wiring 47 arranged on the light source substrate 41. A heat dissipation sheet 82 is placed between the heat dissipation pad 57 and the heat sink 81, and the heat dissipation pad 57, heat sink 81, and heat dissipation sheet 82 are thermally connected. The heat dissipation pad 57 and heat dissipation sheet 82 may be the same as those provided on the light source substrate 41, or they may be different.

[0023] In the camera 1 configured as described above according to this embodiment, the heat generated in each part during operation is smoothly transferred to the housing 10 and dissipated from the outer surface of the housing 10. Specifically, the heat generated in the VCSEL 42 is transferred to the heat dissipation section 71 of the support block 60 through multiple thermal wirings 47, the first heat dissipation pad 46, and the heat dissipation sheet 75, and then transferred to the main body 11 from the lower surface of the support block and the inner surface of the vertical hole 62. The heat generated in the driver IC is transferred to the heat dissipation section 71 of the support block 60 through wiring on the light source substrate 41, the second heat dissipation pad 48, and the heat dissipation sheet 75. The heat generated by the image sensor 56 is transferred to the main body 11 through the thermal wiring 58, heat dissipation pad 57, heat dissipation sheet 82, and heat sink 81. In addition, some of the heat is also transferred to the support block 60 through the element substrate 55.

[0024] Thus, in camera 1, the VCSEL 42, driver IC 43, and image sensor 56 all have heat dissipation paths with good thermal conductivity that reach the main body 11 of the housing 10. As a result, the generated heat can be efficiently dissipated to the outside, and excessive internal temperature rise can be effectively suppressed. Furthermore, the heat dissipation path on the light source substrate 41 side, which includes the heat-generating VCSEL 42 and driver IC 43, passes through the support block 60, which has excellent thermal conductivity and a large volume. As a result, the support block 60 functions as a buffer to temporarily store heat when heat dissipation from the main body 11 is insufficient. Consequently, the external dimensions of the housing 10 are reduced to a volume of 300 cm³. 3 Even at the following compact size, heat dissipation can be performed smoothly, and malfunctions due to high temperatures can be sufficiently suppressed.

[0025] As described above, in the camera 1 according to this embodiment, the light source substrate 41 is in contact with a metal support block 60 that is thermally connected to the housing 10, thereby achieving efficient heat dissipation while ensuring watertightness within the housing 10. As a result, the output of the light source can be increased, which also contributes to extending the distance that can be measured.

[0026] Although one embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment and may include modifications and combinations of the configuration that do not depart from the spirit of the present invention.

[0027] For example, as shown in the modified example of the element substrate 55A in Figure 8, an element heat dissipation pad 59 may be provided on the side where the image sensor 56 is located. By thermally connecting the image sensor to the element heat dissipation pad 59 by wiring (not shown) and bringing the element heat dissipation pad 59 into contact with the support block 60, heat dissipation from the front side of the element substrate 55A can be made even more efficient. Furthermore, a heat dissipation sheet may be placed between the element heat dissipation pad 59 and the support block 60.

[0028] Furthermore, the shape of the vertical hole in the support block and the columnar portion of the housing are not limited to the cylindrical shape shown in the embodiment, but can also be rectangular. By making them rectangular, the contact area between the support block and the housing within the vertical hole can be further increased, making it easier to improve heat dissipation efficiency. However, increasing the contact area requires higher processing precision and tends to complicate assembly work, so a configuration in which the columnar portion is formed slightly smaller and a heat dissipation sheet that is easily deformable is wrapped around it is also effective.

[0029] Furthermore, a portion of the heat dissipation section can be extended upward, so that when the casing lid is closed, the heat dissipation section also contacts the lid. In this case, if the parts of the casing body and lid that the upper and lower surfaces of the heat dissipation section contact are recessed with a bottom, the support block and the casing can also be brought into contact around the upper and lower surfaces, further increasing the contact area between the two. [Explanation of Symbols]

[0030] 1. Camera (distance imaging device) 10 cabinets 30 Main board 40 Imaging Unit 41 Light source substrate 42 VCSEL (Laser Light Source) 43 Driver ICs 46. ​​First Heat Dissipation Pad (Pad) 48. Second heat dissipation pad (second pad) 50 Optical Units 55 Element substrate 56 Image sensor 59-element heat dissipation pad (pad) 60 Support Blocks

Claims

1. An imaging unit having a light source, an optical unit, and an image sensor, A main board for controlling the imaging unit, A metal housing in which the imaging unit and the main board are housed, Equipped with, The imaging unit is A light source substrate on which the aforementioned light source is attached, The image sensor is mounted on an element substrate, It comprises a metal support block that is thermally connected to the housing and supports the optical unit from below, The light source substrate and the element substrate are thermally connected to the support block. Distance imaging device.

2. The light source substrate has a conductive pad on the side opposite to the side on which the light source is located that is thermally connected to the light source, and the light source substrate and the support block are thermally connected at the portion where the pad is located. The distance image acquisition device according to claim 1.

3. The light source substrate has a driver IC for driving the light source and a second conductive pad thermally connected to the driver IC, and the light source substrate and the support block are thermally connected in the area where the pad and the second pad are located. The distance image acquisition device according to claim 2.

4. The light source is a laser light source. The distance image acquisition device according to claim 1.

5. The element substrate has a conductive pad on the side on which the image sensor is placed that is thermally connected to the image sensor, and the element substrate and the support block are thermally connected at the portion where the pad is placed. The distance image acquisition device according to claim 1.

Images