Distance image capturing apparatus

Abstract

This distance image capturing apparatus comprises: an image capturing unit that includes a VCSEL, an optical unit, and an image capturing element; a main substrate that controls the image capturing unit; and a metal housing that accommodates therein the image capturing unit and the main substrate. The image capturing unit includes a light source substrate to which the VCSEL is attached, an element substrate to which the image capturing element 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.

Description

Distance image capturing device

[0001] The present invention relates to a distance image capturing device. This application claims priority to Japanese Patent Application No. 2024-232821 filed in Japan on December 27, 2024, the content of which is incorporated herein by reference.

[0002] An imaging device equipped with a light source is known. As a use of the light source, a flash used for photographing in a dark place is typical. A distance image capturing device, which is a type of imaging device, acquires a distance image based on reflected light reflected by an object from a reference light irradiated from a light source using an imaging element, 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. Furthermore, in the imaging device, the imaging element also generates heat during driving. If the inside becomes too high temperature due to this heat generation, it may cause abnormal operation. In relation to this problem, Patent Document 1 describes an imaging device including a duct having a first intake port through which outside air can flow in, and a centrifugal fan that forcibly causes outside air to flow into the duct from the first intake port. 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.

[0004] Japanese Patent Application Laid-Open No. 2024-136476

[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 intake port. On the other hand, although details will be described later, in a distance image capturing device, there are other situations where it easily becomes high temperature, so more efficient heat dissipation is required compared to a general imaging device equipped with a light source for a flash.

[0006] In view of the above circumstances, an object of the present invention is to provide a distance image capturing device capable of efficient heat dissipation while ensuring internal waterproofness.

[0007] The distance image acquisition device according to the present invention comprises 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 has a light source substrate to which the light source is attached, an element substrate to which the image sensor is attached, and a metal support block that 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.

[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.

[0009] This is a perspective view showing a camera according to one embodiment of the present invention. This is a schematic diagram showing the general configuration of the camera in Figure 1. This is a diagram showing the camera in Figure 1 in disassembled form. This is a diagram showing the imaging unit of the camera in Figure 1 in disassembled form. This is a rear view of the light source substrate of the imaging unit in Figure 4. This is a diagram showing the imaging unit of Figure 4 in one cross-section. This is a diagram showing the imaging unit in a different cross-section than that of Figure 6. This is a diagram showing a modified example of the element substrate related to the imaging unit in Figure 4.

[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 a power supply board 20, a main board 30, and an imaging unit 40. The power supply board 20 is connected to the power supply Es and generates voltages to drive each part 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 appropriately selected and used.

[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 inside 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. Light-shielding covers 4 are attached to the first opening 2 and the second opening 3, so that natural light not used for acquiring distance images (described later) hardly enters the housing 10.

[0013] Figure 4 shows an exploded view of the imaging unit 40. The imaging unit 40 comprises a light source substrate 41 to which a light source is attached, and an optical unit 50 including a lens and an image sensor. In this embodiment, the imaging unit 40 uses two vertical cavity surface-emitting lasers (VCSELs) as light sources, and two VCSELs 42 are attached to the light source substrate 41. VCSELs 42 are just an example, and it is of course possible to use other light sources. The optical unit 50 comprises 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 image sensor 56 is mounted. For example, a CMOS image sensor can be used as the image sensor 56, and it is mounted on the surface of the element substrate 55 facing the first aperture 2. Furthermore, the image sensor 56 is covered by a sensor cover 61 to which a bandpass filter is attached. The image sensor 56 is configured such that light entering the image sensor 56 after passing through the lens 52 passes through a bandpass filter before reaching the image sensor 56. In camera 1, the lens holder 53 is fixed to the sensor cover 61, thereby aligning the lens 52 with respect to the image sensor 56.

[0014] A metal support block 60 is positioned around the lens 52 and 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. The support block 60 is configured so that the heat generated when the VCSEL 42 and image sensor 56 are driven is released to the outside of the housing 10 via the support block 60.

[0015] Camera 1 acquires a distance image based on the reflected light from the reference light emitted from the light source VCSEL 42 and reflected by the target object using an image sensor 56, and measures the distance to the object using the time-of-flight (TOF) method.

[0016] In distance imaging devices, the VCSEL 42 and other light sources used as reference light sources become much hotter than light sources used for flashes, etc., during operation. Furthermore, the driver IC for controlling the VCSEL 42 also generates heat during operation. If this heat is not properly dissipated to the outside of the camera 1, the temperature inside the housing 10 can easily exceed 100°C, which is likely to adversely affect 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 explained in detail below.

[0017] Figure 5 is a view of the light source substrate 41 from the rear. On the rear side, two first heat dissipation pads 46 are formed, one for each VCSEL 42, at a position directly behind the VCSEL 42 to dissipate heat from 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 Figure 6) that penetrate the light source substrate 41 from front to back. In this embodiment, the thermal wirings 47 are through holes, but a conductive layer may be formed on the inner surface or a conductor may be filled in. The dimensions of the first heat dissipation pad 46 can be, for example, a square with sides of 3 mm. Above the first heat dissipation pad 46, two second heat dissipation pads 48 are formed, one for each driver IC 43, to dissipate heat from the driver IC 43. The driver IC 43 and the corresponding second heat dissipation pad 48 are thermally connected by thermal wirings (not shown) that penetrate the light source substrate 41. In this embodiment, the first heat dissipation pad 46, the second heat dissipation pad 48, and the above-mentioned wiring are all made of copper, but they may be made of other materials with excellent thermal conductivity, such as aluminum. As shown in Figure 4, a driver IC 43 corresponding to each of the two VCSELs 42 is mounted on the front surface of the light source substrate 41. The driver IC 43 may be located 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. Heat dissipation sections 71, which are fixed to the housing 10, are provided on both the left and right sides of this space. Each heat dissipation section 71 is located behind the first heat dissipation pad 46 and the second heat dissipation pad 48. Each heat dissipation section 71 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. 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. The inner circumferential surface of the first region 72a and the outer circumferential surface of the columnar portion 11a are in contact via the screw 76, so that the support block 60 and the main body 11 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 portion 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 opening 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 material of the heat sink 81 is preferably 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. Between the heat dissipation pad 57 covering the exposed surface of the thermal wiring 58 and the heat sink 81 arranged in contact with the housing 10, a heat dissipation sheet 82 is arranged to thermally connect the heat dissipation pad 57 and the heat sink 81. The image sensor 56 is thermally connected to the housing 10 via the thermal wiring 58, the heat dissipation pad 57, the heat dissipation sheet 82, and the heat sink 81. The heat dissipation pad 57 and heat dissipation sheet 82 may be the same as or different from those provided on the light source substrate 41. Furthermore, the image sensor 56 and the housing 10 may be thermally connected via columnar thermal wiring 58 exposed on the side opposite to the side where the image sensor 56 is located.

[0023] In the camera 1 according to this embodiment, configured as described above, 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, 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. 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. Heat generated in the image sensor 56 is transferred to the main body 11 through thermal wirings 58, the heat dissipation pad 57, the heat dissipation sheet 82, and the 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. Therefore, 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, including the VCSEL 42 and driver IC 43 which generate a large amount of heat, 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. 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) or the like, 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.

[0030] According to the present invention, it is possible to provide a distance image acquisition device that can efficiently dissipate heat while ensuring internal watertightness.

[0031] 1 Camera (distance image acquisition device) 10 Housing 30 Main board 40 Imaging unit 41 Light source board 42 VCSEL (laser light source) 43 Driver IC 46 First heat dissipation pad (pad) 48 Second heat dissipation pad (second pad) 50 Optical unit 55 Element board 56 Image sensor 59 Element heat dissipation pad (pad) 60 Support block

Claims

1. A distance image imaging 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, wherein the imaging unit comprises: a light source substrate on which the light source is mounted; an element substrate on which the image sensor is mounted; and a metal support block thermally connected to the housing and supporting the optical unit from below, wherein the light source substrate and the element substrate are thermally connected to the support block.

2. The distance image capturing apparatus according to claim 1, wherein the element substrate has columnar thermal wiring exposed on the side opposite to the side on which the image sensor is arranged, and the image sensor and the housing are thermally connected via the thermal wiring.

3. The distance image capturing apparatus according to claim 2, further comprising: a heat sink plate positioned in contact with the housing; a heat dissipation pad covering the exposed surface of the thermal wiring; and a heat dissipation sheet thermally connecting the heat dissipation pad and the heat sink plate.

4. The distance image capturing apparatus according to claim 1, wherein the light source substrate has a conductive pad on the side opposite to the side on which the light source is arranged 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 arranged.

5. The distance image capturing apparatus according to claim 4, wherein 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 portion where the pad and the second pad are located.

6. The distance image capturing apparatus according to claim 1, wherein the light source is a laser light source.

7. The distance image capturing apparatus according to claim 1, wherein the element substrate has a conductive pad on the side on which the image sensor is arranged 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 arranged.

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