JP7693416B2 - Imaging device - Google Patents

Description

The present invention relates to an imaging device.

Conventionally, network cameras with a waterproof structure have been proposed to prevent the intrusion of water such as rain. Also, network cameras equipped with infrared emitting diodes (IR LEDs) have been proposed to record good images even in dark environments (see Patent Document 1). Since the irradiation efficiency of IR LEDs decreases as the temperature increases, network cameras equipped with IR LEDs need to have a heat dissipation structure.

Patent No. 4273498

In recent years, network cameras are required to use resin housings made of resin in order to reduce weight and cost. In the imaging device of Patent Document 1, in order to have a waterproof structure while using a resin housing, for example, a gasket or the like may be placed on the outer periphery of the housing. However, in the imaging device of Patent Document 1, the board on which the IR LED is mounted is in direct contact with the housing, and the IR LED is placed in a position close to the outer periphery of the housing. Therefore, when a certain stress acts at a certain temperature on the part to which the reaction force of the gasket is applied, creep deformation occurs in which the deformation of the part where the stress acts increases over time, and the amount of gasket pressure on the housing may decrease. As a result, the sealing performance of the gasket may decrease, and waterproof performance may not be guaranteed. In addition, if the board is placed so as not to directly contact the housing, the heat of the IR LED cannot be sufficiently dissipated, and the irradiation efficiency of the IR LED may decrease.

The present invention aims to provide an imaging device that can achieve appropriate heat dissipation from infrared light-emitting diodes and suppress deterioration of waterproof performance due to creep deformation of the resin casing.

An imaging device as one aspect of the present invention has a housing formed of resin and including a cover portion and a base portion, a camera portion housed within the housing, a circuit board fixed to the base portion and having an infrared emitting diode mounted on the surface facing the cover portion, a heat dissipation member disposed between the circuit board and the base portion for dissipating heat from the infrared emitting diode, and a sealing member disposed on the outer periphery of the housing while being pressed against the cover portion and the base portion, wherein the infrared emitting diode is disposed on the side closer to the sealing member in the space between the camera portion and the sealing member, the heat dissipation member is not in contact with the inner wall of the housing, and a first insulating space is formed between the heat dissipation member and the base portion so as to overlap with the infrared emitting diode when viewed from the cover portion side, and the base portion has a wall that blocks the first insulating space from the camera portion .

The present invention provides an imaging device that can achieve appropriate heat dissipation from infrared light-emitting diodes and suppress deterioration of waterproof performance due to creep deformation of the resin housing.

1 is an overall view of a network camera which is an example of an imaging device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the network camera. FIG. 2 is an exploded cross-sectional view of the network camera.

The following describes in detail an embodiment of the present invention with reference to the drawings. In each drawing, the same reference numbers are used for the same components, and duplicate descriptions will be omitted.

Figure 1 is an overall view of a network camera 100, which is an example of an imaging device according to an embodiment of the present invention. The network camera 100 has a housing 130 and a lens protection member 140, and is capable of capturing and recording video.

The housing 130 includes a cover portion 110 and a base portion 120. The cover portion 110 and the base portion 120 can each be made by molding a resin such as polycarbonate. The base portion 120 is fixed to a wall or a vehicle by means of a screw or the like through an installation hole. The cover portion 110 and the base portion 120 each include a fastening portion 150, and are fastened to each other by a screw or the like. In this embodiment, the housing 130 is composed of two parts, but may be composed of three or more parts. The cover portion 110 and the base portion 120 may also be fixed to each other by using a claw engagement or adhesive.

The cover part 110 has a window (window part) 160 for irradiating light (IR light) from an infrared light emitting diode (IR LED). The window 160 is molded integrally with the cover part 110 and is made of, for example, black transparent polycarbonate. The window 160 may be adhesively fixed to the cover part 110 or may be screwed together with a waterproof member. The inside of the housing of the window 160 has a lens shape and can collect or diffuse IR light. By irradiating IR light, it is possible to take pictures even in dark environments such as at night. The window 160 is located approximately in the middle of the fastening part 150. This allows the irradiation range of the IR LED to be widened. The window 160 is colored to a color that blocks visible light and transmits IR light. This makes it possible to prevent the components inside the housing from being seen from the outside. The wavelength of IR light is approximately 750 nm to 950 nm.

Lens protection member 140 is hemispherical and protects the lens and other parts housed inside the housing from impact and dust. Lens protection member 140 is fixed to cover section 110 by ultrasonic welding or the like. Because network camera 100 captures images through lens protection member 140, lens protection member 140 is treated as an optical component, and transparency and dimensional accuracy are important. Lens protection member 140 is made of, for example, transparent polycarbonate.

2 is a cross-sectional view of the network camera 100. The housing contains a gasket (sealing member) 180, a camera unit 200, a circuit board 300, an IR LED 320, a heat dissipation member 340, and a holding member 360. The gasket 180 is made of, for example, silicone rubber, and is arranged on the outer periphery of the housing while being pressed against the boundary between the cover unit 110 and the base unit 120. The outer periphery here includes not only the strict outer periphery, but also the substantial outer periphery (approximate outer periphery). The gasket 180 is approximately diamond-shaped and is configured to reduce the reaction force when pressed. Pressing the gasket 180 increases the adhesion of the gasket 180 to the housing 130, thereby exerting sealing performance. This is the same as the sealing structure of an O-ring. The housing 130 is sealed by the lens protection member 140, the window 160, and the gasket 180, and can prevent water and dust from entering the inside of the housing 130. The gasket 180 may be of another shape that generates less reaction force, such as an X-shape or an ellipse. A waterproof sealant or foam may also be used as the gasket 180.

The camera unit 200 is disposed at approximately the center of the housing and includes a lens 210, a lens holder 230, an imaging board 240, a lens cover 250, and a camera holder 260. The lens 210 is screwed and held in the lens holder 230, and can move in the optical axis direction to adjust the focus. The imaging board 240 includes an imaging element and is fixed to the lens holder 230 by adhesive or the like. The imaging element is one of the heat-generating components. If the temperature of the imaging element becomes too high, noise will occur in the image. Therefore, it is necessary to dissipate the heat of the imaging element to the lens cover 250 or the like, and to have a structure that is not affected by heat from another heat source such as a board. For example, a method of insulating by forming a wall that blocks the movement of heat is considered. The lens holder 230 is gripped and fixed to the lens cover 250. Lens cover 250 is made by, for example, die-cast metal or resin molding such as polycarbonate, and is held so as to be covered by camera holder 260 and base part 120, and is configured to be capable of tilting and rotating. An opening for image capture is formed in the front of lens cover 250, and a hole for passing wire 270 or the like is formed in the rear of lens cover 250. Camera holder 260 is made by, for example, resin molding such as polycarbonate, and has a continuous opening from an approximately horizontal position to an approximately vertical position, which is the capture range. Camera holder 260 also regulates the range of tilting of lens cover 250.

The holding member 360 is made of resin molding such as polycarbonate, holds the camera unit 200 via the camera holder 260 so that it can pan and rotate, and is fixed to the base unit 120 using screws or the like. The pan rotation axis is approximately perpendicular to the installation surface. The holding member 360 has an opening so as not to block the irradiation of IR light from the IR LED 320. The holding member 360 also has a rib 364 that surrounds the periphery of the IR LED 320. The rib 364 prevents the IR light from the IR LED 320 from passing through the inside of the housing 130 and entering the lens 210. The rib 364 also prevents the air heated by the IR LED 320 from moving toward the camera unit 200, making it difficult for heat to be transmitted to the camera unit 200.

The circuit board 300 is fixed to the base unit 120 using screws or the like, and is responsible for the overall control functions of the network camera 100, such as control of the IR LED 320, power supply, camera control, and connection to the network. An opening is formed in the center of the circuit board 300, and the camera unit 200 is disposed within the opening. The circuit board 300 and the imaging board 240 are electrically connected by wires 270 or the like. The circuit board 300 and the imaging board 240 may be electrically connected by a flexible board, a flat cable, or a thin coaxial cable or the like. The camera unit 200 converts light received through the lens protection member 140 and the lens 210 into an electrical signal using an imaging element, and transmits it to the circuit board 300. The circuit board 300 records the received video data and distributes it over the network. The IR LED 320 is mounted on the upper surface of the circuit board 300, and is disposed on the side closer to the gasket 180 in the space between the camera unit 200 and the gasket 180. This allows the IR LED 320 to be as close as possible to the cover unit 110 and the window 160, and the irradiation angle can be kept wide. Also, by moving the IR LED 320 away from the camera unit 200, the thermal influence between them can be reduced.

The heat dissipation member 340 is made of a metal plate having high thermal conductivity, such as aluminum, and is disposed between the circuit board 300 and the base portion 120. The heat dissipation member 340 may be made of another metal material, such as copper, or may be made by using a heat diffusion member, such as a graphite sheet, in combination. The heat dissipation member 340 has an extension portion 344 adjacent to the lower surface of the circuit board 300, and dissipates heat from the IR LED 320 from the lower surface side of the circuit board 300. The heat transfer member 370 is disposed in a state sandwiched between the extension portion 344 and the circuit board 300, making it easier to transfer heat from the IR LED 320 to the heat dissipation member 340. The heat transfer member 370 may not be provided, and the extension portion 344 may function as an abutment portion that abuts against the circuit board 300. In addition, a heat insulating section (first heat insulating space) 380 is formed between the extension section 344 and the base section 120 so as to overlap with the IR LED 320 when viewed from the cover section 110 side. The heat dissipation member 340 is in contact with the base section 120 at a position farther from the gasket 180 on the central side than the heat insulating section 380. Furthermore, the heat dissipation member 340 is not in contact with the inner peripheral wall 121 of the base section 120.

The housing contains multiple (two in this embodiment) IR LEDs 320. The two IR LEDs 320 are arranged in approximately point symmetry (at equal intervals along the rotation direction around the pan rotation axis) around the pan rotation axis of the camera unit 200. Therefore, the irradiation range of the IR LEDs 320 covers all directions around the network camera 100. As a result, in a dark shooting environment, the camera unit 200 can shoot regardless of the pan rotation position. In addition, the housing contains multiple (two in this embodiment) heat dissipation members 340. The two heat dissipation members 340 are arranged in approximately point symmetry (at equal intervals along the rotation direction around the pan rotation axis) around the pan rotation axis of the camera unit 200, and dissipate heat from the corresponding IR LEDs 320. Note that in this embodiment, the number of IR LEDs 320 and heat dissipation members 340 is two, but it may be three or more.

Figure 3 is an exploded cross-sectional view of the network camera 100. The heat dissipation of the IR LED 320 will be described below. First, heat dissipation by thermal conduction will be described. When the IR LED 320 irradiates IR light, heat is directly transferred to the circuit board 300. Then, the heat is transferred from the lower surface of the circuit board 300 to the extension 344 of the heat dissipation member 340 via the heat transfer member 370. Since the heat dissipation member 340 has a high thermal conductivity, the heat transferred to the extension 344 is diffused in the surface direction of the heat dissipation member 340. Since the heat dissipation member 340 is fixed to the base portion 120 at a location that avoids the heat insulation portion 380, the heat transferred to the heat dissipation member 340 is transferred to the housing 130 from a location other than the heat insulation portion 380, and is dissipated to the outside of the housing 130.

Next, heat dissipation by thermal convection will be described. On the upper side of the circuit board 300, the air heated by the IR LED 320 convects in the LED space (second heat insulating space) 390 surrounded by the rib 364 and the circuit board 300, and is dissipated from the window 160 to the outside of the housing. Since the rib 364 prevents heat from convection on the side of the camera unit 200, the camera unit 200 and the IR LED 320 are less susceptible to heat from each other. Also, on the lower side of the circuit board 300, the air in the heat insulating section 380 is warmed by the heat transmitted from the IR LED 320 to the extension section 344. However, since solids generally have a higher thermal conductivity than gases, most of the heat from the IR LED 320 is diffused toward the surface direction of the heat dissipation member 340 through the above-mentioned heat conduction path. This prevents the air in the heat insulating section 380 from becoming too hot. In addition, in order to prevent air heated directly from the underside of the circuit board 300 from moving toward the camera unit 200, the base unit 120 is formed with a wall 122 that separates the heat insulating unit 380 from the camera unit 200. Furthermore, in the projection plane viewed from above the housing (when viewed from the cover unit 110 side), the heat insulating unit 380 and the LED space 390 are formed to overlap. This allows the heat of the IR LED 320 to be concentrated in the extension unit 344, and the heat can be quickly diffused by the thermal conduction of the solid heat dissipation member 340.

By dissipating heat from the IR LED 320 in the above-described configuration, the heat from the IR LED 320 is less likely to be transmitted to the vicinity of the IR LED 320 on the base unit 120 or to the camera unit 200.

In this embodiment, the gasket 180 is arranged in a pressed state to ensure the waterproof performance of the housing. Therefore, the reaction force of the gasket 180 acts on the cover part 110 and the base part 120 in a direction in which they open from each other. The base part 120 has a shape closer to a plate than the cover part 110, so it has low rigidity and is easily deformed. In addition, position A, which is near the IR LED 320 of the base part 120, is easily deformed because it is away from the fastening part 150. If position A, where the reaction force of the base part 120 acts, is heated, creep deformation may occur. If the base part 120 deforms, the amount of pressure applied by the gasket 180 decreases. As a result, the sealing performance of the gasket 180 may decrease, and the waterproof performance may not be guaranteed.

In this embodiment, the heat dissipation member 340 and the heat insulating section 380 make it difficult for heat to be transmitted to position A of the base section 120. In other words, the high temperature that causes creep deformation can be suppressed, and therefore the occurrence of creep deformation can be suppressed.

As described above, the configuration of this embodiment can provide an imaging device that can achieve appropriate heat dissipation from the infrared light-emitting diode and suppress deterioration of the waterproof performance due to creep deformation of the resin housing.

The above describes preferred embodiments of the present invention, but the present invention is not limited to these embodiments, and various modifications and variations are possible within the scope of the gist of the invention.

100 Network camera (imaging device)
110 Cover portion 120 Base portion 121 Inner peripheral wall 130 Housing 180 Gasket (sealing member)
200 Camera unit 300 Circuit board 320 Infrared light emitting diode 340 Heat dissipation member 380 Heat insulation unit (heat insulation space)

Claims (12)

a housing including a cover portion and a base portion and formed of resin;
A camera unit accommodated in the housing;
a circuit board fixed to the base portion and having an infrared emitting diode mounted on a surface of the cover portion;
a heat dissipation member disposed between the circuit board and the base portion and configured to dissipate heat from the infrared light emitting diode;
a sealing member disposed on an outer periphery of the housing in a state pressed against the cover portion and the base portion,
the infrared emitting diode is disposed on a side closer to the sealing member in the space between the camera unit and the sealing member,
the heat dissipation member does not contact an inner peripheral wall of the housing,
a first heat insulating space is formed between the heat dissipation member and the base portion so as to overlap with the infrared emitting diode when viewed from the cover portion side;
The imaging device , wherein the base portion includes a wall that separates the first heat insulating space from the camera portion . 2. The imaging device according to claim 1 , further comprising a holding member disposed between the cover portion and the circuit board, for rotatably holding the camera portion. 3. The imaging device according to claim 2 , wherein the holding member includes a rib that covers a periphery of the infrared light emitting diode. 4. The imaging device according to claim 3 , wherein the infrared light emitting diode is disposed inside a second heat insulating space surrounded by the rib and the circuit board. 5. The imaging device according to claim 4 , wherein the first heat insulating space and the second heat insulating space are formed to overlap each other when viewed from the cover portion side. 6. The imaging device according to claim 1 , wherein the heat dissipation member has a contact portion that contacts the circuit board. 6. The imaging device according to claim 1 , further comprising a heat transfer member disposed in a state sandwiched between the circuit board and the heat dissipation member. 8. The imaging device according to claim 1 , wherein the camera unit is disposed in an opening formed in the center of the circuit board. 9. The imaging device according to claim 1 , wherein the number of the infrared light emitting diodes and the number of the heat dissipation members are plural. 10. The imaging device according to claim 9 , wherein the infrared light emitting diodes and the heat dissipation members are arranged at equal intervals along a rotation direction about a pan rotation axis of the camera unit. The imaging device according to claim 1 , wherein the heat dissipation member is in contact with the base portion on a central side of the first heat insulating space. The imaging device according to claim 1 , wherein the cover portion includes a window portion through which light from the infrared light emitting diode passes.