Cooling device

Abstract

The goal is to improve the cooling efficiency of the cooling system. [Solution] The Peltier module comprises at least two Peltier elements stacked on top of each other, including a first Peltier element and a second Peltier element; a body to be cooled disposed on the cooling surface side of the first Peltier element; a base member disposed on the heat dissipation side of the second Peltier element; and a fixing member that fixes the second Peltier element to the base member by pressing the cooling surface of the second Peltier element, wherein the cooling surface of the first Peltier element is exposed from the fixing member on the side of the body to be cooled.

Description

Technical Field

[0001] The present invention relates to a cooling device, and particularly to a Peltier module having a cooling capacity based on the Peltier effect.

Background Art

[0002] It is known that the imaging sensor of a general imaging device generates dark current as the temperature rises, and the noise increases. The noise caused by the dark current deteriorates the quality of the captured image, particularly in night surveillance or photography in a dark place. To prevent such deterioration of the captured image quality, there is an imaging device that cools the imaging sensor using a cooling means such as a Peltier element and then performs imaging (Patent Document 1).

[0003] FIG. 9 shows an example of a structure using a conventional configuration as a cooling mechanism for an imaging sensor using a Peltier element. As shown in FIG. 9, in the conventional cooling mechanism, one side surface of the fixing member 530 is arranged to contact the cooling surface of the Peltier element 510, and is fastened to the base member 540 by a plurality of fastening members 550. As a result, the Peltier element 510 is sandwiched between the fixing member 530 and the base member 540.

[0004] The fixing member 530 is made of a material with high thermal conductivity, and on the side opposite to the surface in contact with the Peltier element 510, the imaging sensor 520 is attached so as to contact. Thus, when the temperature of the cooling surface of the Peltier element 510 drops, the temperature of the imaging sensor 520 can be lowered through the fixing member 530. In FIG. 9, the imaging sensor 520 is mounted on the sensor substrate 521. Also, a heat insulating member 560 is arranged between the fixing member 530 and the base member 540. Further, a heat insulating washer 570 is arranged between the fastening member 550 and the fixing member 530.

[0005] Furthermore, regarding Peltier elements, a Peltier module has been proposed in which multiple Peltier elements are stacked in a unidirectional manner. By using a multi-stage configuration with multiple elements stacked, the amount of heat absorbed by the Peltier module increases, which has the effect of increasing the temperature difference during cooling. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2007-104573 [Patent Document 2] Japanese Patent Application Publication No. 4-106376 [Overview of the project] [Problems that the invention aims to solve]

[0007] In the conventional configuration, a reaction force is applied from the Peltier element 510 to the fixing member 530 and the base member 540 that hold the Peltier element 510. On the other hand, since the image sensor 520 requires precise optical adjustments such as flange back adjustment, it is preferable to reduce the external force applied to the image sensor 520. For this reason, it is not preferable to fix the Peltier element 510 with the image sensor 520, and in the conventional configuration, the Peltier element 510 is fixed with the fixing member 530.

[0008] However, the conventional configuration of cooling the image sensor 520 via a fixed member 530 has the problem of reduced cooling efficiency compared to the case where the cooling surface of the Peltier element and the image sensor are in direct contact without a fixed member. For this reason, there has been room for improvement in cooling devices that cool objects that are sensitive to external forces, such as image sensors.

[0009] Therefore, the objective of the present invention is to improve the cooling efficiency of a cooling device. [Means for solving the problem]

[0010] A cooling device according to one embodiment of the present invention comprises a Peltier module in which at least two Peltier elements, including a first Peltier element and a second Peltier element, are stacked; a body to be cooled disposed on the cooling surface side of the first Peltier element; a base member disposed on the heat dissipation side of the second Peltier element; and a fixing member that fixes the second Peltier element to the base member by pressing the cooling surface of the second Peltier element, wherein the cooling surface of the first Peltier element is exposed from the fixing member on the side of the body to be cooled. [Effects of the Invention]

[0011] According to the present invention, the cooling efficiency of a cooling device can be improved. [Brief explanation of the drawing]

[0012] [Figure 1] This is a perspective view of a cooling device according to Embodiment 1 of the present invention. [Figure 2] Figure 1 is an exploded perspective view of the cooling device shown. [Figure 3] Figure 1 is an exploded perspective view of the top cover unit of the cooling device shown. [Figure 4] Figure 1 is an exploded perspective view of the bottom unit of the cooling device shown. [Figure 5] Figure 1 is a plan view of the bottom unit of the cooling device shown. [Figure 6] Figure 1 is a cross-sectional view of the bottom unit of the cooling device. [Figure 7] Figure 1 is a partial cross-sectional view of the bottom unit of the cooling device shown in Figure 1. [Figure 8] Figure 1 is a partial cross-sectional perspective view of the bottom unit of the cooling device shown. [Figure 9] This is a partial cross-sectional view showing an example of a cooling mechanism for an image sensor using a conventional Peltier element. [Modes for carrying out the invention]

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments. Also, the following embodiments do not limit the present invention according to the claims, and not all combinations of the features described in this embodiment are essential for the solution means of the present invention. In each figure, the same members or elements are given the same reference numerals, and duplicate descriptions are omitted or simplified. Also, in the following embodiments, an example of a cooling device for cooling an imaging sensor will be described, but the object to be cooled is not limited to the imaging sensor.

[0014] <Embodiment 1> FIG. 1 is a perspective view of a cooling device according to Embodiment 1 of the present invention. The cooling device 10 includes a top cover unit 100 and a bottom unit 200. FIG. 2 is an exploded perspective view of the cooling device 10.

[0015] The bottom unit 200 includes an imaging sensor 220 mounted on a sensor substrate 221 and a Peltier module 210 (see FIG. 4). The top cover unit 100 includes a front window 120, transmits light incident along the optical axis shown in FIG. 1, and guides it to the imaging sensor 220 of the bottom unit 200.

[0016] The cooling surface temperature of the Peltier module 210 may be below the dew point temperature of the ambient air, and condensation may occur in the low temperature part. If water vapor enters the inside of the cooling device 10, the sensor substrate 221 may be short-circuited due to condensation, so it is preferable to reduce the amount of water vapor entering from the outside. Therefore, the cooling device 10 compresses the base member packing 260 by fastening the top cover unit 100 to the bottom unit 200, and forms a sealed space inside. The Peltier module 210 and the sensor substrate 221 are housed in the sealed space of the cooling device 10. Here, the base member packing 260 is preferably made of butyl rubber or fluororubber, which is difficult to transmit water vapor and has high airtightness.

[0017] Figure 3 is an exploded perspective view of the top cover unit 100. As shown in Figure 3, the front window 120 and the front window packing 140 are compression-held by the top cover 110 and the front window pressing member 130. The top cover unit 100 maintains the airtightness of the portion where the front window 120 is attached by compression-holding the front window packing 140. The front window packing 140 is preferably made of butyl rubber or fluorine rubber, which is difficult to permeate water vapor and has high airtightness.

[0018] The front window 120 is made of a material such as transparent glass in order to transmit the light incident along the optical axis direction shown in Figure 1. Also, the top cover 110 is preferably made of a metal such as an aluminum alloy, which has high airtightness.

[0019] Next, referring to Figures 4 to 7, the configuration of the bottom unit 200 will be described. Figure 4 is an exploded perspective view of the bottom unit 200. Figure 5 is a plan view of the bottom unit 200. Figure 6 shows a cross-sectional view of the bottom unit 200. Figure 7 is a partial cross-sectional view showing only the members around the Peltier module 210 in the bottom unit 200.

[0020] The Peltier module 210 is a Peltier module in which a plurality of Peltier elements including the first Peltier element 211 and the second Peltier element 212 are stacked and integrated so that the heat flow is in one direction. The Peltier module 210 has an effect of increasing the heat absorption amount of the Peltier module 210 and increasing the temperature difference during cooling by adopting a multi-stage configuration in which a plurality of stages are stacked. The Peltier module 210 is connected to a control board (not shown) via the Peltier module cable 213.

[0021] In the Peltier module 210, where Peltier elements are stacked, the first Peltier element 211 is located at the top, and the second Peltier element 212 is located at any of the other stages. The top position in the Peltier module 210 is the position closest to the image sensor 220. Here, the area of ​​the second Peltier element 212 is larger than the area of ​​the first Peltier element 211. The Peltier module 210 is arranged so that its heat dissipation surface is in contact with the Peltier module mounting portion 241 of the base member 240. The base member 240 is positioned on the side of the heat dissipation surface of the second Peltier element 212.

[0022] The fixing member 230 has a fixing member opening 231 in the center. The fixing member opening 231 opens from the side of the Peltier module 210 to the side of the object to be cooled, i.e., the side of the image sensor 220. The opening area of ​​the fixing member opening 231 is larger than the area of ​​the first Peltier element 211 and smaller than the area of ​​the second Peltier element 212. The fixing member 230 is fastened to the base member 240 by a plurality of fastening members 250 with one side of the fixing member 230 in contact with the second Peltier element 212. As a result, the second Peltier element 212 of the Peltier module 210 is sandwiched between the fixing member 230 and the base member 240, and the Peltier module 210 is fixed. In other words, the fixing member 230 fixes the second Peltier element 212 to the base member 240 by pressing the cooling surface of the second Peltier element 212. At this time, the cooling surface of the first Peltier element 211 is exposed through the fixing member opening 231. The cooling surface of the first Peltier element 211 is exposed from the fixing member 230 through the fixing member opening 231 on the side of the object to be cooled, i.e., the side of the image sensor 220. The cooling surface of the first Peltier element 211 exposed from the fixing member 230 comes into contact with the image sensor 220, which is the object to be cooled, and the image sensor 220 is cooled by the cooling surface of the first Peltier element 211.

[0023] The image sensor 220, which is the object to be cooled, is mounted on a sensor substrate 221, which has a substrate opening 225 (see Figure 6). At least a portion of the back surface of the image sensor 220 is exposed to the Peltier module 210 side through the substrate opening 225 of the sensor substrate 221. Therefore, at least a portion of the exposed image sensor 220 comes into contact with the cooling surface of the first Peltier element 211, and the image sensor 220 is cooled. The back surface of the image sensor 220 is the surface closer to the Peltier module 210. The substrate opening 225 opens the sensor substrate 221 from the mounting surface of the image sensor 220 to the back surface.

[0024] The opening area of ​​the substrate opening 225 is larger than the area of ​​the first Peltier element 211. The first Peltier element 211 is positioned to penetrate the substrate opening 225. The sensor substrate 221 is fastened to the fixing member 230 with the imaging sensor 220 and the cooling surface of the first Peltier element 211 in contact. This allows the temperature of the imaging sensor 220, which is in contact with the first Peltier element 211, to decrease as the temperature of the cooling surface of the first Peltier element 211 decreases. The imaging sensor 220 is connected to the control board via the imaging sensor FPC 222. FPC is an abbreviation for Flexible printed circuit. The imaging sensor 220, which is the object to be cooled, is positioned on the cooling surface side of the first Peltier element 211.

[0025] The base member 240 is equipped with heat dissipation fins 270 on the side opposite to the Peltier module mounting portion 241. As a result, heat from the imaging sensor 220 is transferred from the Peltier module 210 to the base member 240 and then to the heat dissipation fins 270, and is then discharged to the outside by a heat sink such as a fan (not shown).

[0026] As shown in Figure 5, the base member 240 has a first connection through-hole 242 and a second connection through-hole 243. The imaging sensor FPC 222 is routed to the outside of the cooling device 10 through the first connection through-hole 242. The Peltier module cable 213 is routed to the outside of the cooling device 10 through the second connection through-hole 243. The imaging sensor FPC 222 and the Peltier module cable 213, routed to the outside of the cooling device 10, are connected to a control board where image processing and control signal processing are performed.

[0027] Furthermore, the gaps between the imaging sensor FPC 222, the Peltier module cable 213, and the base member 240 are sealed with an elastic material such as rubber or an adhesive to maintain the airtightness of the cooling device 10. Alternatively, the imaging sensor FPC 222 and the Peltier module cable 213 may be routed together to the outside of the cooling device 10 through a single through-hole.

[0028] The base member 240 is preferably made of a metal such as an aluminum alloy that has high airtightness and high thermal conductivity. The Peltier module mounting portion 241 should have a flat surface with low surface roughness in order to efficiently transfer the heat from the Peltier module 210 to the base member 240. In addition, a sheet or grease with excellent thermal conductivity may be applied to increase the thermal conductivity between the Peltier module 210 and the base member 240.

[0029] Since the image sensor 220 requires precise optical adjustments such as flange back adjustment, it is preferable to minimize the external force applied to the image sensor 220. The Peltier module 210 is fixed by the second Peltier element 212 being sandwiched between the fixing member 230 and the base member 240. As described above, the fixing member 230 fixes the second Peltier element 212 to the base member 240 by pressing the cooling surface of the second Peltier element 212. Therefore, a reaction force is generated from the second Peltier element 212 to the fixing member 230 and the base member 240 with which it is in contact. On the other hand, the sensor substrate 221 on which the image sensor 220 is mounted is fastened to the fixing member 230. In this way, the reaction force generated by the fixing of the Peltier module 210 is not directly applied to the sensor substrate 221, but is distributed to the second Peltier element 212, thus reducing the reaction force applied to the sensor substrate 221. This makes it possible to suppress the pressing force (external force) applied to the image sensor 220 while keeping the first Peltier element 211 in contact with the image sensor 220.

[0030] However, the pressing force generated at the contact surface between the image sensor 220 and the cooling surface of the first Peltier element 211 may increase due to tolerance variations in the components. Therefore, it is preferable to apply a grease with excellent thermal conductivity between the image sensor 220 and the cooling surface of the first Peltier element 211 to absorb the tolerances.

[0031] In the Peltier module 210, the first Peltier element 211 is positioned so as to penetrate the substrate opening 225 of the sensor substrate 221. Therefore, the area of ​​the first Peltier element 211 must be smaller than the opening area of ​​the substrate opening 225. On the other hand, the area of ​​the second Peltier element 212 is larger than the area of ​​the first Peltier element 211. A larger area for the second Peltier element 212 increases the heat dissipation area of ​​the Peltier module 210, which improves the heat dissipation efficiency to the heat dissipation fins 270.

[0032] Figure 8 is a partial cross-sectional perspective view of the bottom unit 200, showing only the components surrounding the Peltier module 210. The sensor substrate 221 has an FPC connector 223 to which the imaging sensor FPC 222 is connected, and a chip resistor 224 mounted on it. The FPC connector 223 and chip resistor 224 are examples of electronic components. The FPC connector 223 and chip resistor 224 are mounted on the back surface of the mounting surface of the imaging sensor 220 on the sensor substrate 221.

[0033] Here, the z-direction height of the FPC connector 223 and the chip resistor 224 is lower than the z-direction height of the first Peltier element 211. The z-direction is perpendicular to the component mounting surface of the sensor substrate 221. The z-direction is the optical axis direction. This makes it possible to position the sensor substrate 221 without the FPC connector 223 and the chip resistor 224 interfering with the Peltier module 210 and the fixing member 230.

[0034] Next, we will compare the conventional configuration with this embodiment and explain the effects of this embodiment. As shown in Figure 9, in the conventional cooling mechanism, the fixing member 530 is fastened to the base member 540 by a plurality of fastening members 550 with one side of the fixing member 530 in contact with the cooling surface of the Peltier element 510. As a result, the Peltier element 510 is sandwiched between the fixing member 530 and the base member 540.

[0035] The fixing member 530 is made of a material such as metal with high thermal conductivity, and is mounted so that the image sensor 520 is in contact with the side opposite to the surface in contact with the Peltier element 510. As a result, when the temperature of the cooling surface of the Peltier element 510 decreases, the temperature of the image sensor 520 can be lowered via the fixing member 530.

[0036] Here, the fixing member 530 is in contact with the cooling surface of the Peltier element 510 and is therefore at a low temperature, while the base member 540 is in contact with the heat dissipation side of the Peltier element 510 and is therefore at a high temperature. In this case, to prevent heat from flowing back from the base member 540 to the fixing member 530, an insulating member 560 is placed between the fixing member 530 and the base member 540. The insulating member 560 is made of a material with low thermal conductivity, such as resin or urethane. In addition, to prevent heat from flowing back from the base member 540 to the fixing member 530 through the fastening member 550, an insulating washer 570 made of a material such as resin or urethane is placed between the fastening member 550 and the fixing member 530.

[0037] On the other hand, as shown in Figure 7, in this embodiment, the cooling surface of the Peltier module 210 and the image sensor 220 are in direct contact. This allows for more efficient cooling of the image sensor 220 compared to the conventional configuration in which the image sensor 520 is cooled via the fixing member 530 shown in Figure 9. Furthermore, the fixing member 230 in this embodiment does not need to be made of a metal material, and is preferably made of an insulating material with a lower thermal conductivity than metal, such as resin or urethane. By making the fixing member 230 out of an insulating material, the insulating member 560 and insulating washer 570 that were required in the conventional configuration can be reduced.

[0038] Furthermore, even if the inside of the cooling device is sealed, it is difficult to eliminate moisture within the sealed area. In the conventional configuration shown in Figure 9, the metal fixing member 530 is at a low temperature, which can cause condensation on the surface of the fixing member 530 and potentially short-circuit the sensor substrate 521. On the other hand, in this embodiment shown in Figure 7, when the fixing member 230 is made of an insulating material, the temperature of the fixing member 230 does not drop easily, which has the effect of suppressing the occurrence of condensation.

[0039] Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of its gist.

[0040] This embodiment includes the following configuration. (Composition 1) A Peltier module in which at least two Peltier elements, including a first Peltier element and a second Peltier element, are stacked, The object to be cooled is placed on the cooling surface side of the first Peltier element, A base member positioned on the heat dissipation side of the second Peltier element, A fixing member that fixes the second Peltier element to the base member by pressing the cooling surface of the second Peltier element, Equipped with, The cooling surface of the first Peltier element is exposed from the fixing member on the side of the object to be cooled. A cooling device characterized by the following features. (Configuration 2) The area of ​​the second Peltier element is larger than the area of ​​the first Peltier element. The cooling device according to configuration 1, characterized by the features described above. (Composition 3) The fixing member has a fixing member opening that opens from the side of the Peltier module to the side of the object to be cooled, The cooling surface of the first Peltier element is exposed from the fixing member on the side of the object to be cooled, through the opening of the fixing member. The area of ​​the fixing member opening is larger than the area of ​​the first Peltier element. The area of ​​the fixing member opening is smaller than the area of ​​the second Peltier element. A cooling device according to configuration 1 or configuration 2, characterized by the above. (Composition 4) The fixing member secures the second Peltier element to the base member by sandwiching the second Peltier element between the fixing member and the base member. A cooling device according to any one of configurations 1 to 3, characterized by the features described above. (Composition 5) The aforementioned fixing member is made of a material with a lower thermal conductivity than metal. A cooling device according to any one of configurations 1 to 4, characterized by the features described above. (Composition 6) The object to be cooled is an imaging sensor. A cooling device according to any one of configurations 1 to 5, characterized by the features described above. (Composition 7) The sensor board has the aforementioned imaging sensor mounted on it. The sensor substrate has a substrate opening that opens from the mounting surface of the image sensor to the back surface, At least a portion of the imaging sensor is exposed through the substrate opening. The cooling device according to configuration 6, characterized by the features described above. (Composition 8) The aperture area of ​​the substrate opening is larger than the area of ​​the first Peltier element. The first Peltier element is positioned to penetrate the substrate opening, The cooling device according to configuration 7, characterized by the features described above. (Composition 9) The cooling device according to configuration 7 or 8, characterized in that the cooling surface of the first Peltier element, which is positioned to penetrate the substrate opening, contacts the image sensor, which is at least partially exposed from the substrate opening, thereby cooling the image sensor. (Composition 10) The sensor substrate has electronic components mounted on the back surface of the mounting surface of the imaging sensor, The height of the electronic component in the optical axis direction is lower than the height of the first Peltier element in the optical axis direction. A cooling device according to any one of configurations 7 to 9, characterized by the features described above. (Composition 11) The cooling surface of the first Peltier element exposed from the fixed member is in contact with the object to be cooled. A cooling device according to any one of configurations 1 to 10, characterized in that the object to be cooled is cooled. [Explanation of symbols]

[0041] 10 Cooling device 100 Top Cover Unit 200 Bottom Unit 110 Top Cover 120 Front window 130 Front window retaining member 140 Front window gasket 210 Peltier Module 211 First Peltier element 212 Second Peltier element 213 Peltier module cable 220, 520 imaging sensors 221, 521 Sensor board 222 Imaging sensor FPC 223 FPC connector 224 chip resistors 225 substrate opening 230, 530 Fixing members 231 Fixing member opening 240, 540 base members 241 Peltier module mounting section 242 First connection through hole 243 Second connection through hole 250, 550 fastening members 260 Base component packing 270 heat dissipation fins 510 Peltier element 560 Insulation material 570 Insulating Washer

Claims

1. A Peltier module comprising at least two Peltier elements, including a first Peltier element and a second Peltier element, stacked on top of each other, The object to be cooled is placed on the cooling surface side of the first Peltier element, A base member disposed on the heat dissipation side of the second Peltier element, A fixing member that fixes the second Peltier element to the base member by pressing the cooling surface of the second Peltier element, Equipped with, The cooling surface of the first Peltier element is exposed from the fixing member on the side of the object to be cooled. A cooling device characterized by the following features.

2. The area of ​​the second Peltier element is larger than the area of ​​the first Peltier element. The cooling device according to feature 1.

3. The fixing member has a fixing member opening that opens from the side of the Peltier module to the side of the object to be cooled, The cooling surface of the first Peltier element is exposed from the fixing member on the side of the object to be cooled, through the opening of the fixing member. The area of ​​the fixing member opening is larger than the area of ​​the first Peltier element. The area of ​​the fixing member opening is smaller than the area of ​​the second Peltier element. The cooling device according to feature 1.

4. The fixing member secures the second Peltier element to the base member by sandwiching the second Peltier element between the fixing member and the base member. The cooling device according to feature 1.

5. The aforementioned fixing member is made of a material with a lower thermal conductivity than metal. The cooling device according to feature 1.

6. The object to be cooled is an imaging sensor. The cooling device according to feature 1.

7. The sensor board has the aforementioned imaging sensor mounted on it. The sensor substrate has a substrate opening that opens from the mounting surface of the image sensor to the back surface, At least a portion of the imaging sensor is exposed through the substrate opening. The cooling device according to feature 6.

8. The aperture area of ​​the substrate opening is larger than the area of ​​the first Peltier element. The first Peltier element is arranged so as to penetrate the substrate opening. The cooling device according to feature 7.

9. The cooling device according to claim 7 or 8, characterized in that the cooling surface of the first Peltier element, which is positioned to penetrate the substrate opening, is in contact with the image sensor, which is exposed to at least a portion of the substrate opening, thereby cooling the image sensor.

10. The sensor substrate has electronic components mounted on the back surface of the mounting surface of the imaging sensor, The height of the electronic component in the optical axis direction is lower than the height of the first Peltier element in the optical axis direction. The cooling device according to feature 7.

11. The cooling surface of the first Peltier element exposed from the fixed member is in contact with the object to be cooled. The cooling device according to claim 1, characterized in that the object to be cooled is cooled.

Images