JP2007274565A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus which has improved imaging accuracy by efficiently cooling an imaging element and can be easily miniaturized. <P>SOLUTION: The imaging apparatus 1 is provided with the imaging element 2 thermally coupled to a Peltier element 4, and a heat radiator 20 thermally coupled to the Peltier element 4. The heat radiator 20 is configured to include two strip-like heat pipes 6, 7 arranged so as to cross. The heat radiator 20 has a heat transfer 9 in which a crossing section 9a is coupled to the Peltier element 4 and four strips 6a, 7a protruding from the crossing section 9a extend in the same direction so as to surround a circuit board 12; and a heat diffuser 19 in which the imaging element 2 and the heat transfer 9 are surrounded, the external surfaces of the strips 6a, 7a are thermally coupled to the internal surface, and a plurality of protrusions 13a for heat diffusion are formed on the external surface. In the imaging apparatus 1, a ventilating gap SL is formed between the adjacently extending strips 6a, 7a, and ventilating ports 16b, 18a communicating to the gap SL are formed on the heat diffuser 19. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an imaging apparatus including a Peltier element that cools an imaging element.

  In an image pickup apparatus using an image pickup element such as a CCD element or a C-MOS sensor, when the temperature of the image pickup element rises, noise increases due to an increase in dark current components, and the performance of the image pickup apparatus deteriorates. Therefore, there is known an image pickup apparatus that cools the image pickup element with a Peltier element, dissipates heat generated in a heat dissipation portion of the Peltier element through a heat transfer member, and discharges hot air with a fan motor. (See Patent Document 1)

JP 2002-329991 A

  Since the Peltier element for cooling the imaging element is locally heated, it is necessary to effectively dissipate heat generated in the Peltier element. For this reason, when the fan motor is brought closer to the Peltier element, the distance between the image sensor and the fan motor becomes closer, and the imaging accuracy of the image sensor decreases due to the vibration of the fan motor. On the other hand, if the Peltier element is cooled with a water-cooled radiator without using a motor fan, the imaging device becomes large, and it is difficult to achieve both improvement in imaging accuracy and downsizing. .

  An object of the present invention is to provide an imaging device that effectively cools an imaging element to improve imaging accuracy and is easy to miniaturize.

  An image pickup apparatus according to the present invention includes an image pickup element, a lens unit disposed on the optical axis of the image pickup element, a circuit board electrically connected to the image pickup element, and a heat absorption part facing the image pickup element. And a heat radiator thermally coupled to the heat radiating portion of the Peltier element, and the heat radiator is configured to include two strip-shaped heat pipes arranged to cross each other. A heat transfer portion in which the crossing portions of the belt-like heat pipes are coupled to the Peltier element, and the four belt portions protruding from the crossing portions extend in the same direction so as to surround the circuit board, and the imaging device and the heat transfer portion. Surrounding, the outer surface of the band portion is thermally coupled to the inner surface, and the outer surface has a heat dissipation portion formed with a plurality of protrusions for heat dissipation and extends adjacently A gap for ventilation is formed between them, and the heat dissipation part communicates with the gap. Wherein the vent is formed.

  According to this imaging apparatus, heat generated in the imaging element is absorbed by the Peltier element, and heat radiation from the Peltier element is dissipated from the heat dissipation unit via the heat transfer unit of the radiator. The heat transfer portion extends in the same direction so that the crossing portion of the two belt-like heat pipes is coupled to the Peltier element, and the four belt portions protruding from the crossing portion surround the circuit board. The outer surface of the belt portion is thermally coupled to the inner surface of the heat dissipating portion, and the outer surface of the heat dissipating portion has a plurality of heat dissipating portions formed on the outer surface of the circuit board. Heat is effectively dissipated toward the outside. Furthermore, a gap for ventilation is formed between adjacent bands, and a vent hole communicating with the gap is formed in the heat dissipation part, so that the inside of the band is also vented. The heat inside the band is also difficult to collect. As a result, the heat radiation from the Peltier element is effectively dissipated to effectively cool the imaging element, thereby suppressing the generation of noise, and it is easy to achieve both improvement in imaging accuracy and downsizing.

  Furthermore, it is preferable that the belt-shaped heat pipe is a self-excited vibration heat pipe having a meandering tubule through which the working fluid circulates. A self-excited vibration type heat pipe changes its phase when the working fluid filled in the meandering tubule absorbs heat, and the liquid phase vibrates due to nucleate boiling that transports latent heat using the movement of steam. There is a heat pipe that uses it to transport sensible heat. According to a belt-like heat pipe made of a self-excited vibration heat pipe, it is light and easy to bend, and has a high thermal conductivity and heat transfer effect, compared to a conventional heat pipe loaded with a wick. Furthermore, since there are few restrictions on arrangement | positioning and it has the characteristic that it is hard to influence thermal conductivity in which direction, it becomes difficult to be influenced by the direction of an imaging device, and it becomes possible to use it for a wide range of uses.

 Further, the heat dissipating part extends along the longitudinal direction of the band part and is in contact with the outer surface of the band part, and the cylindrical heat sink part so as to close the opening of the cylindrical heat sink part. A front heatsink part fixed to the front end and having a window formed on the optical axis of the image sensor, and a cover fixed to the rear end of the cylindrical heatsink part so as to close the rear opening of the cylindrical heatsink part It is preferable that the ventilation hole is formed in the front heat sink part and the cover part. The cylindrical heat sink part extends along the longitudinal direction of the band part, vent holes are formed on the front end side and the rear end side of the cylindrical heat sink part, and the gap between adjacent band parts is cylindrical. Since it is formed along the heat sink part, the air easily flows in the cylindrical heat sink part, and it is difficult for heat to stay inside the cylindrical heat sink part.

  According to the present invention, the imaging element can be effectively cooled to improve imaging accuracy, and can be easily downsized.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of an imaging device according to the invention will be described in detail with reference to the drawings.

[First embodiment]
As shown in FIGS. 1 and 2, the imaging device 1 is a device that images a subject with a CCD element (imaging device) 2, and is mainly attached to a precision optical instrument such as a microscope or an astronomical telescope. The CCD element 2 is an electronic coupling element that sequentially outputs charges accumulated according to the amount of light along a time series, and is heated by long-time imaging. When the temperature of the CCD element 2 rises due to this heat, noise due to dark current is generated. Therefore, the Peltier element 4 is thermally coupled to the back surface 2a of the CCD element 2 through the heat absorption side block 3 made of copper. Has been.

  The back surface 2 a of the CCD element 2 is in contact with the front surface 3 a of the heat absorption side block 3, and the back surface 3 b of the heat absorption side block 3 is in contact with the heat absorption part 4 a of the Peltier element 4. By sandwiching the heat absorption side block 3 which is a heat conducting member between the CCD element 2 and the Peltier element 4, the difference in shape between the back surface 2a of the CCD element 2 and the heat absorption part 4a of the Peltier element 4 can be absorbed. And the thermal bond can be stabilized. Further, the heat conducting member may be a metal member such as aluminum or silver having high heat conductivity, or an alloy member made by fusing metals such as aluminum, copper and silver. It may be a member obtained by processing a substance containing carbon or the like into a paste or foil. Further, the back surface 2a of the CCD element 2 and the heat absorption part 4a of the Peltier element 4 may be fixed with an adhesive such as an epoxy resin having high thermal conductivity without sandwiching the heat absorption side block 3. Good.

  The Peltier element 4 is a semiconductor element that emits heat absorbed by the heat absorbing part 4a from the heat radiating part 4b by passing a direct current. The heat radiating portion 4b of the Peltier element 4 is in contact with the front surface 5a of the rectangular heat radiation side block 5 made of copper, which is a heat conducting member. The CCD element 2 is screwed to the heat absorption side block 3, and the heat absorption side block 3 is screwed to the heat radiation side block 5 with the Peltier element 4 interposed therebetween. And the back surface 5b of the heat radiation side block 5 contacts the center of the 1st strip | belt-shaped heat pipe 6, and is adhere | attached with the adhesive agent with high heat conductivity. The 1st strip | belt-shaped heat pipe 6 is a member which bent the one side part and the other side part at right angle in the same direction on both sides of the center part of a long plate-shaped self-excited vibration type heat pipe. Note that, similarly to the heat absorption side block 3, the heat radiation side block 5 also absorbs the difference in shape between the Peltier element 4 and the first belt-like heat pipe 6, and between the Peltier element 3 and the first belt-like heat pipe 6. Stabilize mechanical and thermal bonds.

  As shown in FIG. 3, the second belt-shaped heat pipe 7 having the same shape as that of the first belt-shaped heat pipe 6 intersects with the center rear surface of the first belt-shaped heat pipe 6 so as to be orthogonal to each other, and has a high thermal conductivity. It is glued with. The first belt-like heat pipe 6 and the second belt-like heat pipe 7 arranged to intersect each other constitute a heat transfer section 9. The Peltier element 4 is thermally coupled to the intersection 9a between the first belt-like heat pipe 6 and the second belt-like heat pipe 7 via the heat radiation side block 5 (see FIG. 2). Further, the two belt portions 6a of the first belt-like heat pipe 6 protruding from the intersecting portion 9a are bent rearward and extend along the front-rear direction so as to be parallel to each other. Similarly, the two belt portions 7a of the second belt-shaped heat pipe 7 protruding from the intersecting portion 9a are also bent rearward and extend in the same direction as the belt portion 6a. Further, a ventilation gap SL is formed between the adjacent strips 6a and 7a extending in the same direction.

  The first belt-like heat pipe 6 and the second belt-like heat pipe 7 are self-excited vibration heat pipes (commonly referred to as “heat lanes” or “meandering tubule-type heat pipes”). There is a heat pipe that changes phase when absorbing heat, vibrates the liquid phase by nucleate boiling that transports latent heat using the movement of vapor, and transports sensible heat using this vibration. According to the self-excited vibration heat pipe, it is lighter and easier to bend than the conventional heat pipe loaded with a wick, and the first belt-like heat pipe 6 and the second belt-like heat pipe 7 can be easily machined.

  As shown in FIGS. 2 and 3, a heat insulating plate 11 having a rectangular groove cut out to form a ventilation groove is bonded to the back side of the intersecting portion 9a of the first and second belt-like heat pipes 6 and 7. Yes. Further, the circuit board 12 is fixed on the back side of the heat insulating plate 11 and in a space surrounded by the four belt portions 6a and 7a of the first and second belt-like heat pipes 6 and 7. The circuit board 12 is electrically connected to the CCD element 2, and a circuit for processing an electrical image signal output from the CCD element 2 is mounted on the circuit board 12.

  The inner surfaces of the rectangular heat sink portions 13 are bonded to the outer surfaces of the band portions 6a and 7a of the first and second belt-shaped heat pipes 6 and 7, respectively, and four heat sink portions are bonded to each other with an adhesive having high thermal conductivity. 13 (see FIG. 1) extends along the longitudinal direction of the strips 6a and 7a, and surrounds the first and second strip-shaped heat pipes 6 and 7, the Peltier element 4 and the CCD element 2. A plurality of flat plate-like protrusions 13 a extending in the front-rear direction are formed in parallel on the outer surface of each heat sink portion 13. The heat transmitted from the band portions 6a and 7a to the heat sink portion 13 is dissipated from the protruding portion 13a. A cylindrical heat sink portion 14 is constituted by the first and second belt-like heat pipes 6 and 7 and the four heat sink portions 13 surrounding the CCD element 2. The band portions 6a and 7a of the first and second belt-like heat pipes 6 and 7 and the heat sink portion 13 may be fixed by brazing, or each band portion using an aluminum plate. 6a, 7a and the heat sink part 13 may be inserted and screwed.

  As shown in FIGS. 1 and 2, a rectangular front heat sink portion 16 is screwed to the front end of the cylindrical heat sink portion 14 so as to close the front opening of the cylindrical heat sink portion 14. A window portion 16a is formed at the center of the front heat sink portion 16, and vent holes 16b are formed at four corners. Further, on the front surface of the front heat sink portion 16, a plurality of flat plate-like protruding portions 16c extending in the vertical direction are formed in parallel. The window portion 16a is disposed on the optical axis S of the CCD element 2, and the lens unit 17 is screwed and fixed to the window portion 16a. The optical system of the lens unit 17 takes in the subject light and forms an image on the light receiving surface 2 a of the CCD element 2.

  Heat is transmitted from the cylindrical heat sink part 14 to the front heat sink part 16 and is dissipated from the protruding part 16c. The back surface 2a of the CCD element 2 is cooled in the range of −20 ° C. to −10 ° C. by the Peltier element 4. When the light receiving surface 2a of the CCD element 2 is below the outside air temperature, it becomes cloudy due to condensation and cannot be imaged. However, in the present embodiment, the front heat sink portion 16 has heat, and the proximity of the light receiving surface 2b of the CCD element 2 is kept above the ambient temperature by the heat, so that the occurrence of condensation can be effectively prevented.

  A rectangular cover 18 is screwed to the rear end of the cylindrical heat sink 14 so as to close the rear opening of the cylindrical heat sink 14. Vents 18 a are formed at the four corners of the cover portion 18. The vent 18a of the cover 18 and the vent 16b of the front heat sink 16 communicate with the gap SL between the adjacent strips 6a and 7a, and the gap SL is both Are located on a straight line connecting the vent holes 16b and 18a. Therefore, the air flowing through both the vents 16b and 18a easily flows smoothly along the gap SL, and prevents heat from being trapped in the band portions 6a and 7a in which the circuit board 12 is accommodated. The cylindrical heat sink 14, the front heat sink 16 and the cover 18 constitute a heat dissipating part 19, and the heat dissipating part 19 and the heat transfer part 9 constitute a radiator 20.

  According to the imaging apparatus 1 described above, the heat generated by the CCD element 2 is absorbed by the Peltier element 4, and the heat radiated from the Peltier element 4 is transmitted from the heat dissipation unit 19 via the heat transfer unit 9 of the radiator 20. Dissipated. The heat transfer unit 9 includes first and second belt-like heat pipes 6 and 7, and an intersection 9 a between the first and second belt-like heat pipes 6 and 7 is coupled to the Peltier element 4. The projecting four strips 6a and 7a extend in the same direction so as to surround the circuit board 12. And since the heat-dissipating part 19 is thermally coupled to the outer surfaces 6b, 7b of the band parts 6a, 7a, and a plurality of projecting parts 13a for heat dissipation are formed on the outer surface of the heat-dissipating part 19. The heat is effectively released not to the inside of the circuit board 12 but to the outside. Further, a gap SL for ventilation is formed between the adjacent strips 6a and 7a, and vent holes 16b and 18a communicating with the gap SL are formed in the heat dissipation section 19. For this reason, the insides of the belt portions 16b and 18a are also ventilated, and the inside of the belt portions 16b and 18a is also difficult to trap heat. As a result, the heat radiated from the Peltier element 4 is effectively dissipated to suppress the generation of noise, and it is easy to achieve both improvement in imaging accuracy and downsizing.

  Furthermore, since the first and second belt-like heat pipes 6 and 7 constituting the heat transfer unit 9 are self-excited vibration heat pipes, they have extremely high thermal conductivity about 30 times that of copper. Therefore, heat can be quickly transferred to the heat dissipating unit 19 from the Peltier element 4 that has locally become high temperature to be dissipated, thereby preventing heat from being trapped inside the image pickup apparatus 1. Furthermore, the self-excited vibration heat pipe is easy to bend. When the first and second belt-shaped heat pipes 6 and 7 are formed by the self-excited vibration heat pipe, natural convection according to the use direction of the image pickup apparatus 1 is generated. It is easy to process into a shape that tends to occur, and effective heat dissipation becomes possible.

  Furthermore, since effective heat dissipation can be achieved without using a water-cooled radiator, the size and weight can be easily reduced, and handling is easier than in the case of cooling with water. Furthermore, since effective heat dissipation is possible without using a fan motor, the imaging device 1 can be easily miniaturized, and noise caused by vibration of the fan motor can be prevented.

  In addition, conventional heat pipes loaded with wicks have vertical and vertical restrictions on heat conduction, and when using conventional heat pipes in imaging devices where the installation and use directions are not fixed, there is room for heat pipe installation space. In order to maintain the heat conduction performance even if the installation and use direction changes, it is necessary to increase the number of heat pipes. Therefore, when a conventional heat pipe is used, it is difficult to reduce the size and the manufacturing cost is likely to increase. However, by forming the heat transfer portion 9 using a self-excited vibration heat pipe, the decrease in thermal conductivity due to the direction of use becomes very small, and it is easy to arrange to promote natural convection.

  Furthermore, in conventional heat pipes, the thermal conductivity differs depending on the installation direction, so it is difficult to design an imaging device that changes the installation usage direction in consideration of the amount of heat dissipated, but using self-excited vibration heat pipes By forming the heat transfer part 9, the thermal conductivity does not change depending on the installation direction, and it is easy to design in consideration of the amount of heat dissipated.

(Modification)
In the imaging apparatus 1 described above, the cylindrical heat sink portion 14 of the heat dissipating portion 19 and the protruding portions 13a and 16c of the front heat sink portion 16 are flat. In this modification, a plurality of rod-like protrusions 20 a are formed on the cylindrical heat sink portion 20. By using such a plurality of rod-like protrusions 20a, it becomes difficult to be influenced by the direction of natural convection that dissipates heat, and effective heat dissipation becomes possible.

  The present invention is not limited to the above-described embodiment. For example, the image sensor may be a C-MOS sensor.

1 is a perspective view showing a first embodiment of an imaging apparatus according to the present invention. It is sectional drawing along the II-II line of FIG. It is a perspective view of a heat transfer part. It is a perspective view which shows the modification of the protrusion part formed in the cylindrical heat sink part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Imaging device, 2 ... CCD element (imaging element), 4 ... Peltier element, 4a ... Heat absorption part, 4b ... Heat dissipation part, 6 ... 1st strip | belt-shaped heat pipe, 6a ... Strip | belt part, 7 ... 2nd strip | belt-shaped heat pipe, 7a ... belt part, 9 ... heat transfer part, 9a ... crossing part, 12 ... circuit board, 13a, 20a ... projecting part, 14 ... cylindrical heat sink part, 16 ... front heat sink part, 16a ... window part, 16b ... vent , 17 ... lens unit, 18 ... cover part, 18b ... vent, 19 ... heat dissipation part, 20 ... radiator, S ... optical axis, SL ... gap.

Claims (3)

An image sensor;
A lens unit disposed on the optical axis of the image sensor;
A circuit board electrically connected to the imaging device;
A Peltier element that is directed to the heat-absorbing portion toward the image-pickup element and is thermally coupled to the image-pickup element;
A heat radiator thermally coupled to the heat radiating portion of the Peltier element,
The radiator is
The circuit board includes four belt-shaped heat pipes arranged to intersect each other, the intersecting portions of the belt-shaped heat pipes are coupled to the Peltier element, and the four belt portions protruding from the intersecting portions A heat transfer section extending in the same direction so as to surround
Surrounding the image pickup device and the heat transfer unit, the inner surface is thermally coupled to the outer surface of the band portion, and the outer surface includes a heat dissipation unit formed with a plurality of protrusions for heat dissipation. Have
An image pickup apparatus, wherein a gap for ventilation is formed between the adjacent belt portions extending, and a vent hole communicating with the gap is formed in the heat dissipation portion.   2. The imaging apparatus according to claim 1, wherein the belt-shaped heat pipe is a self-excited vibration heat pipe having a meandering tubule through which a working fluid circulates. The heat-dissipating part extends along the longitudinal direction of the band part and is in contact with the outer surface of the band part, and the cylinder is configured to close the front opening of the cylindrical heat sink part. A front heat sink portion fixed to the front end of the cylindrical heat sink portion and having a window portion formed on the optical axis of the imaging device, and a rear opening of the cylindrical heat sink portion so as to close the cylindrical heat sink portion. A cover portion fixed to the rear end,
The imaging device according to claim 1, wherein the vent is formed in the front heat sink portion and the cover portion.

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