JP3400114B2 - Cooling system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device for electronic parts such as CCDs used in video cameras and the like, and more particularly to a cooling device using a heat pipe and a Peltier element.

[0002]

2. Description of the Related Art Conventionally, in an electronic circuit or the like, a heat transfer system such as a radiator plate or a heat pipe is used to radiate heat from the circuit in order to suppress a temperature rise due to heat generation from the circuit. Further, Peltier elements and the like are also used, and cooling is performed using these. In a video camera or the like, the temperature characteristic of the image pickup element affects the image quality, so that the cooling is performed particularly efficiently. In general,
Image sensor used in video cameras (CCD: CHARGE
It is known that fixed pattern noise called base unevenness increases exponentially with increasing temperature, and deteriorates image quality.

In addition, the inside of the video camera is mounted in a high-density circuit for miniaturization, and not only the CCD self-heats, but also the temperature rises due to the heat generated by the surrounding electric circuit.
Since the temperature of the CD becomes high, the above fixed pattern noise increases. Therefore, as shown in FIGS. 4 and 5, cooling is performed using a Peltier element or a heat pipe. As shown in FIG. 4, the Peltier device 100 includes an N-type semiconductor 103 and a P-type semiconductor 104, which are metal plates 101 and 10.
It is an element that couples at 2a and 102b and transfers heat from one coupling surface to the other coupling surface. By supplying a direct current I from the constant current source I to the closed circuit as shown in FIG. 4, a temperature difference can be given between the coupling surfaces, and the metal plate 101
It is well known that a Peltier element works as a heat pump that draws heat from a heating element (for example, CCD) located on the side and discharges the heat from the other metal plate 102a, 102b side. In the example of FIG. 4, a pair of P,
This is an example of N semiconductors. Normally, the required number of P
The N-type semiconductors are electrically connected in series and thermally connected in parallel to obtain a desired cooling performance. In the following description, the high temperature side coupling surface to which the temperature difference of the Peltier element is given is denoted by TH, and the low temperature side coupling surface is denoted by TC.

The heat pipe 200 shown in FIG.
It is a pipe for heat transportation, which has much higher thermal conductivity than metal conductors, and utilizes the enthalpy difference during the phase change of the working fluid (for example, water) enclosed in the pipe, that is, latent heat to make heat efficient. It is carried from one end to the other end. As shown in FIG. 5, in this heat transportation, the water vaporized in the evaporation section becomes a vapor flow, and this vapor flow is transferred to the condensation section via the heat insulation section due to the difference in vapor pressure in the pipe and liquefied. Caused by. In this way, heat transfer using vaporized vapor flow and condensation by liquefaction transports a much larger amount of heat than heat transfer in metals. The temperature difference between the two ends of the heat pipe is theoretically almost 0 degrees, as is clear from the solid-liquid three-phase diagram (see Fig. 6), but in reality, the vapor flow and condensation heat transfer Since there is a finite heat transfer coefficient between them, thermal resistance is generated, and this heat resistance reduces the amount of heat transferred. In addition, heat resistance also occurs due to the form of heat transfer (radiation, conduction or convection) from the heating element to the heat pipe or from the heat pipe to the cooling source, and the amount of heat transferred is reduced. It is the point when using.

A description will be given below by taking as an example the case where the Peltier device and the heat pipe described above are used for cooling the image pickup unit in the video camera. First, a cooling device using a Peltier element will be described with reference to FIG. FIG. 7 is a partially enlarged view of an image pickup unit in a commercial video camera and a cabinet to which heat is transferred from the image pickup unit.
Looking at the subject to the left for the part to transfer D and heat,
The figure shows the entire video camera as viewed from the front.

As shown in FIG. 7, image information from a subject is formed on the CCD 1 through an optical system composed of a lens and a prism and converted into an electric signal. CCD1 is
It is packaged, has a large number of two-dimensionally arranged light receiving portions and signal reading portions, and is housed in the package 1A. The package 1A has a substantially rectangular parallelepiped shape, and the light receiving portion is provided with a window for transmission so that light rays can pass therethrough. A plurality of input / output lead wires 1B are provided so that the light receiving portion is on the front side and the CCD 1 extends to the back side of the package 1A from one opposing side surface. By supplying power and control signals to these lead wires 1B, the light receiving section and the signal reading section of the CCD 1 are driven, and the image information of the subject is taken out as an electric signal. Also, this drive unit and power supply unit (not shown)
Is also provided and mounted around the CCD package 1A.
The CCD package 1A is made of ceramic having a high thermal conductivity. Further, an optical system such as a prism is arranged on the window side of the CCD package 1A, and the focus position is adjusted and fixed by an adhesive. In addition,
For simplicity, only the adhesive layer 1C between the filter 1D and the CCD package 1A is shown in the drawing.

The cabinet 7 of the video camera is made of metal, which is a good conductor of heat, and the cabinet 7 contains C
An image pickup unit including the CD 1 and the optical system is housed. In order to mount the CCD package 1A, the head substrate 11 is arranged on the lead wire side of the CCD package 1A. The head substrate 11 is fixed to a cabinet or the like with, for example, auxiliary metal fittings (not shown).
The lead wire 1B of the CCD package 1A is the head substrate 11
It is fitted into the through hole formed in the hole and is firmly connected electrically and mechanically with the solder 12. This board 11
The above-mentioned drive circuit, power supply circuit, and the like are mounted on the top.
The lead wire 1B is provided slightly longer, and the Peltier device 100a is arranged between the head substrate 11 and the CCD package 1A so that it can be mounted. The Peltier element 100a has the P-type as described in the description of FIG.
A plurality of unit structures each consisting of a metal type and an N-type semiconductor and a metal plate are electrically connected in series and thermally in parallel. In practice, the low temperature side TC is coupled to a heating element, High temperature side T
Since the H is joined to the heat transfer means, the metal plate 10
In order to electrically insulate 1 and 102a and 102b and allow thermal coupling, for example, an alumina ceramic substrate (not shown) having a large insulation resistance and a good thermal conductivity is fixed to the surface thereof. There is. further,
A copper plate (not shown) is provided on each surface of the alumina ceramic substrate, and the surface indicated by TC or TH in FIG. 4 is formed by the exposed surface of the copper plate. It is possible to connect the exposed surface to the heating element or the heat transfer means with a large contact area. Further, since the metal fitting 2 for transferring the heat from the CCD package 1A to the cabinet 7 is fixed to the cabinet 7, the mounting fitting 5 extends from the cabinet 7 to the CCD side, and one end of this fitting 5 is the cabinet. It is fastened to 7 with a screw 9a. Further, the other end fixes the metal fitting 2 provided for transmitting the heat from the heat generating portion, so that the auxiliary metal fitting 6a faces the protruding arm portion 5a with a gap.
Is provided. The auxiliary metal fitting 6a is fastened to the overhanging arm portion 5a by using a screw 8a, and is placed so that the metal fitting 2 is sandwiched between the auxiliary metal fitting 6a and the overhanging arm portion 5a. The metal fitting 2 is clamped by being mechanically applied with an appropriate pressure, and this pressure is applied to the heat conductive resin piece 3a and the heat conductive resin piece 3a which are respectively inserted between the metal fitting 2 and the arm 5a and the auxiliary metal fitting 6a. It is adjusted by the thickness of the rubber piece 4a. That is, by adjusting the thicknesses of the rubber piece 4a and the heat conductive resin piece 3a, an appropriate pressing force is obtained and a sufficient pressure to be fixed is obtained. Further, with such a configuration, heat is efficiently conducted and mechanical strength is maintained. On the other hand, on the lead wire side of the CCD package 1A, the Peltier device 100a is
Is arranged so that TH is directed to the image pickup unit side and TH is directed to the head substrate side. Silicon grease, for example, is applied to the low temperature side TC of the Peltier element 100, and the CCD package 1A and the Peltier element 100a are connected with a substantially large contact area, that is, with a low thermal resistance. Also, a wire rod (not shown) for wiring is drawn out from the Peltier element, and this wire rod and a power supply terminal of a constant current source (not shown) are connected to each other so as to obtain electrical coupling. Has become. The constant current source I is arranged on the head substrate or near the Peltier element with a short wire.

A metal fitting 2 is provided on the high temperature side TH so that the heat from the Peltier element 100a can be directly transferred to the cabinet 7. In addition,
A rubber 20 is inserted between the head substrate 11 and the metal fitting 2, and the fitting 2 is pressed to apply pressure to ensure contact between the CCD package 1, the Peltier element 100a, and the fitting 2. Moreover, the cabinet 7 is formed of a metal that is a good conductor and has a large contact area with the outside air. Therefore, the transferred heat is released to the outside air and the temperature rise of the CCD can be prevented.

However, in the above apparatus, when the amount of heat absorbed by the Peltier element 100a is transferred by the metal fitting 2, there is a problem that the heat loss in the metal fitting 2 is large and a sufficient cooling effect cannot be obtained. This is because the absorbed heat is radiated, but even if a metal fitting having a high thermal conductivity is used for this generated heat, the cross-sectional shape of the metal fitting 2 is so large due to the internal volume of the video camera. This is because heat cannot be efficiently guided from the CCD 1 to the outside air.

The above is a conventional example using the Peltier element 100. Next, a cooling device using the heat pipe 200 will be described with reference to FIG. What is the above configuration CCD
The part that absorbs heat from 1A and the fixing method to the cabinet 7 are different, and one end of the heat pipe 200 is coated with silicon grease or the like on the back surface of the CCD package 1A.
It is thermally coupled with a substantial contact area increased. Heat is transferred from this one end to the other end through the heat pipe 200 having good thermal conductivity without loss. The other end of the heat pipe 200 is also thermally bonded by applying silicon grease or the like to the cabinet 7 to increase the substantial contact area and guide the heat from the CCD 1 to the outside air without loss. Therefore, the temperature rise of the CCD 1 can be prevented. The cabinet 7 is provided with a fitting 6 for fixing one end of the heat pipe 200. In the metal fitting 6 for attachment, one flat plate is bent to the opposite side at a substantially right angle, and the respective bent surfaces are substantially parallel. On one side of this bent surface,
In order to insert the screw 9, a hole slightly larger than the outer shape of the screw 9 to be inserted is provided. This surface is arranged on the cabinet 7, and the other bent surface is separated by a gap to form the CCD 1.
Distribute to the side. The cabinet 7 is internally threaded, and the central axis of the hole of the mounting bracket 6 and the central axis of the screw are aligned with each other, and the screw 9 is screwed into the cabinet while applying force and turning. By doing so, a mechanical connection between the auxiliary metal fitting 6 and the cabinet 7 is obtained. After that, one end of the heat pipe 200 is arranged in the gap between the cabinet 7 and the mounting metal fitting 6, and the heat conductive resin piece 3 is arranged on the cabinet side and the rubber 4 is arranged on the metal fitting side so as to sandwich the heat pipe 200. After that, the screw 9 is turned until the head of the screw 9 contacts the mounting member 6. After that, a more appropriate torque is applied to the screw 9, and the heat pipe 200 and the heat conductive resin 3 are fastened to the cabinet 7 by pressing the rubber 4 to mechanically and thermally connect the heat pipe 200 and the cabinet 7. Is getting

On the other hand, the other end of the heat pipe 200 arranged on the back surface of the package 1A is arranged so as to be thermally coupled to the back surface of the package 1A. The package 1A is provided with a lead wire 1B for obtaining electrical coupling, and a power supply and a control signal are supplied from the lead wire 1B. After the lead wire 1B is fitted into the through hole of the board 11 between the lead wire 1B and the head substrate 11, liquid solder is poured into a land pattern portion including the lead wire and the through hole protruding from the board surface 11. When this solder cools and solidifies, the CCD package 1A
Are fixed to the head substrate 11. The package 1A has a substantially rectangular parallelepiped shape, and the lead wires 1B are provided on one of opposite side surfaces of the package 1A. Therefore, the other end of the heat pipe 200 is CC
Inserted from the other side of the D package 1A,
It is arranged on the back surface of the package 1A. This heat pipe 2
In order to obtain a thermal bond between the other end of 00 and the package 1A, the rubber 20 is inserted between the heat pipe 200 and the head substrate 11 and pressure is applied to the package 1A side.
This pressure provides reliable thermal contact between the CCD package 1A and the heat pipe 200. The rubber pieces 4 and 20 and the heat conductive resin piece 3 have elasticity,
It acts as a cushioning material for preventing displacement of the CCD 1 while applying pressure, and stress caused when an excessive external force is applied to the CCD package 1A by these heat conductive resin pieces 3 and rubber pieces 4. It is configured to absorb and maintain mechanical strength. With such a configuration, the heat generated from the CCD 1 can be guided to the outside air and the temperature of the CCD 1 can be prevented from rising.

However, when the heat pipe 200 is used, even if the heat is transferred without loss, it is impossible to lower the temperature of the CCD 1 to a temperature below the outside air due to the nature of the heat pipe 200, and the outside air temperature is low. If high, CCD
There was a problem that 1 could not be cooled sufficiently. That is, the heat pipe 200 can transport heat without loss, but is affected by the ambient temperature.
When the outside air temperature is high, there is a problem that the CCD is not sufficiently cooled.

Further, when the Peltier element or the heat pipe is used alone, or when the power consumption of the electronic circuit or the like is extremely large, the temperature inside the camera cabinet rises abnormally and the CCD is not sufficiently cooled. There was a problem.

[0014]

As described above, when the Peltier element is used, heat cannot be sufficiently transferred to the cabinet due to the restriction of the internal volume of the container such as the camera cabinet, and the heating element such as CCD is used. There was a problem that it could not be cooled sufficiently. Also, when using a heat pipe, even if heat can be transported without loss, CC
There is a problem that the temperature of the heating element such as D cannot be lowered to the temperature below the outside air.

Further, when the power consumption of other electronic circuits housed in the container becomes extremely large, the temperature inside the container rises abnormally due to the restriction of the internal volume, and the CCD
However, there is a problem that the heating element is not sufficiently cooled.

Therefore, the present invention has been made in view of such problems.
An object of the present invention is to provide a cooling device capable of sufficiently cooling electronic components such as CCD even when the power consumption of the electronic circuit housed in the container is high or the outside temperature is high.

[0017]

A cooling device according to the present invention as set forth in claim 1, wherein a heating element, a container formed of a material having a high thermal conductivity for accommodating the heating element, and a low temperature side are located in front.
The first Peltier element bonded to the heating element and the high temperature side
A second Peltier element joined to the inner wall of the container;
The end is joined to the high temperature side of the first Peltier element and the other end
Is a heat joined to the low temperature side of the second Peltier element
A heat transfer path having a pipe and connecting the heating element to the inner wall of the container is provided.

A cooling device according to the present invention as defined in claim 2 is
The cooling device according to claim 1, wherein the heating element is CC
The image pickup device is a D image pickup device .

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[Action] In the present invention according to claim 1, transfers heat from the calling thermal body absorbs heat at a first Peltier element, until near the inner wall of the container by no loss heat pipe endothermic thermal from the heating side Can be installed on the inner wall .
At 2 of the Peltier element, Ru can dissipate efficiently to the outside air pumped heat from conductor with ambient air and a wide contact surface.
Electric current is supplied to each of the first and second Peltier elements to give a temperature difference, and a temperature difference obtained by adding the temperature differences of the respective Peltier elements is given between the outside air and the heating element to obtain the temperature of the heating element. To
Can cool down to a temperature below the outside air, and has a great cooling effect
Can be obtained.

According to the second aspect of the present invention, the generated heat is efficiently transferred to the outside air by joining the CCD image pickup element as the heat generating element to the container by the heat transfer path having the Peltier element and the heat pipe. It can be diffused and the fixed pattern noise of the CCD image pickup device can be reduced.

[0027]

EXAMPLES Examples will be described with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a cooling device according to the present invention. Similar to FIGS. 7 and 8, the image pickup unit portion in the video camera is shown in a partially enlarged view. The same components will be described with the same reference numerals. In the present embodiment, as shown in FIG. 1, heat from the heating element, that is, CCD 1, is absorbed on the TC side of the Peltier element, and the heat pipe 200 is connected to the TH side from which the absorbed heat is released. , Efficiently transfers heat to the cabinet. First, the configuration of FIG. 1 will be described. A Peltier element 100a is arranged between one end of the conventional heat pipe 200 shown in FIG. 8 and the package 1A of the CCD 1.

First, the Peltier element 100a is arranged on the back surface of the package 1A and temporarily fixed by a jig or the like. One end of the heat pipe 200 is connected to the high temperature side TH of the Peltier element 100a.
Distribute to Further, the other end of the heat pipe 200 is arranged between the mounting bracket 6 and the cabinet 7 as in the conventional example, and the heat pipe 200 is provided between the heat conductive resin piece 3 and the rubber piece 4.
After arranging so as to sandwich it, lightly tighten with the screw 9. After that, the rubber piece 20 for pressing is inserted between the other end of the heat pipe 200 arranged in advance on the CCD 1 side and the head substrate 11, and the package 1A and the Peltier element 1 are inserted.
00a and Peltier element 100a and heat pipe 2
A thermal and mechanical connection with 00 is obtained. After the rubber is carefully and carefully inserted so that the CCD 1 is not displaced and an excessive external force is not applied, the other end of the heat pipe 200 is further tightened with the screw 9 of the metal fitting to completely fix it. In this way, the Peltier element 100a and the heat pipe 200 form a heat transfer path, and the heat generated from the CCD 1 is transferred to the cabinet 7 of a good conductor. Also,
The wire drawn from the Peltier element 100a is connected to the power supply terminal of the constant current source I on the head substrate 11, for example, and a predetermined current is supplied from the constant current source I.

As the heat pipe, it is preferable to use a heat pipe having a small temperature gradient at both ends of the heat pipe, that is, high heat transfer efficiency. Further, the heat pipe is deformable and the heat transfer path can be freely configured. desirable.

The CCD package 1A, the Peltier element 100a, the heat pipe 200 and the heat pipe 2 are also provided.
00, the resin piece 3, and the cabinet 7 are preferably coated with silicon grease or the like to increase the substantial contact area. Using the resin piece 3 and the rubber piece 4 on the contact surface coated with this silicon grease,
By applying pressure evenly, you get a reliable thermal contact,
Lowering the thermal resistance. Therefore, the resin piece 3 and the rubber piece 4 have a uniform pressure on the contact surface,
It is desirable that the two facing surfaces are substantially parallel to each other, and it is desirable that the contact area be as large as possible. Further, the metal used in the heat transfer path described above, for example, the cabinet 7 or the like, is preferably a metal having a good thermal conductivity, and the material is typically aluminum, stainless steel, copper or the like. Can be mentioned. Further, as the heat conductive resin 3, it is desirable to use a resin having a good thermal conductivity, and for example, a silicone (silicon polymer) resin or the like can be mentioned.

The operation of FIG. 1 will be described. Conventionally, it was impossible to lower the temperature to below the outside air due to the influence of the outside air temperature, but in the present embodiment, the low temperature side TC of the Peltier element 100a is reduced.
Are arranged in the package 1A to absorb heat generated from the package 1A. Since the Peltier element 100a can give a predetermined temperature difference between one coupling surface and the other coupling surface by passing a predetermined current I, the temperature of the joint surface with the CCD 1 is different from the ambient temperature. It is possible to provide a temperature difference between them. For example, assuming that the outside air temperature is T degrees, one end of the heat pipe, that is, the Peltier element side can be set to T-ΔT degrees lower than this temperature by ΔT degrees. Therefore, this can solve the conventional problem that the temperature of the CCD 1 cannot be lowered to T degrees or lower, and the CCD package 1A can be sufficiently cooled. Since sufficient cooling is performed in this way, fixed pattern noise in the image of the video camera can be reduced. With the above configuration, the CCD can be sufficiently cooled even when the outside air temperature rises.

FIG. 2 is a diagram showing another embodiment of the cooling device according to the present invention. The same components as those in FIGS. 7 and 8 are designated by the same reference numerals for description. In the present embodiment, the above object is achieved by arranging the Peltier device 100a arranged on the back surface of the CCD package 1A in the embodiment of FIG. 1 on the cabinet side 7. The retainer has the same structure as the conventional example, and by adjusting the thickness of the rubber pieces 4 and 20 of the retainer, an appropriate pressure is applied to the contact portion, and the thermal and mechanical properties are the same as in the embodiment of FIG. Have a positive bond. The TC of the Peltier element 100a is arranged on the heat pipe 200 side,
Place TH on the cabinet side. The TC side of the Peltier element 100a is connected to the heat conductive resin piece 3, and TH
Is connected to the inner wall of the cabinet. Since silicone grease or the like is applied to these contact surfaces and an appropriate pressure is applied using a rubber piece, a reliable thermal contact can be obtained. Further, the other end of the heat pipe 200 is arranged on the surface of the CCD package 1A on the side of the lead wire 1B, and the contact surface between this end and the CCD package 1A is pressed by the rubber piece 4 so as to be thermally heated. And mechanically connected securely. Therefore, as in the embodiment of FIG. 1, the CCD 1 can be lowered to T-ΔT degree.

FIG. 3 is a diagram showing another embodiment of the cooling device of the present invention, which is an example in which FIG. 1 and FIG. 2 are combined, and the temperature of the CCD 1 can be further lowered. That is,
Heat pipe 200 using two Peltier elements 100a
Place on both ends of.

These thermal and mechanical connections are shown in FIG.
Similar to the embodiment of FIG. 2, silicon grease or the like is applied to each contact surface of the heat transfer path, and an appropriate pressure is applied by the rubber piece and the resin piece. In this embodiment, by using two Peltier elements, a temperature difference of 2ΔT can be provided, and the CCD 1 can be further cooled as compared with the embodiments of FIGS.

With the above configuration, CC
D can be cooled sufficiently, and the occurrence of fixed pattern noise in the camera image can be reduced.

In the present embodiment, the example in which the CCD is used as the heating element is described, but the present invention is not limited to this, and can be widely applied to a cooling device using an electronic circuit as the heating element.

[0037]

As described above, according to the present invention, it is possible to easily construct a heat transfer system for sufficiently cooling the CCD by variously combining the Peltier device and the heat pipe. Further, even if the number of parts is increased, high-density mounting can be performed by easily combining a deformable heat pipe and a Peltier element to form a heat transfer system. Further, a sufficient cooling effect can be obtained, and as a ripple effect thereof, generation of fixed pattern noise that causes deterioration of the camera image can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a cooling device according to the present invention.

FIG. 2 is a view showing another embodiment of the cooling device according to the present invention.

FIG. 3 is a view showing another embodiment of the cooling device according to the present invention.

FIG. 4 is a diagram illustrating an operation of a Peltier device.

FIG. 5 is a diagram illustrating an operation of a heat pipe.

FIG. 6 is a state diagram showing a gas-liquid solid three-phase state of a working fluid in a heat pipe.

FIG. 7 is a diagram showing a conventional cooling device using a Peltier element.

FIG. 8 is a diagram showing another example of a conventional cooling device using a heat pipe.

[Explanation of symbols]

1 ... CCD (heating element) 100, 100a ... Peltier element 200 ... Heat pipe

Claims (2)

(57) [Claims] 1. A heating element, a container formed of a material having a high thermal conductivity for containing the heating element therein, and a first Peltier element having a low temperature side joined to the heating element.
And a second Peltier whose high temperature side is joined to the inner wall of the container.
Element and one end is in contact with the high temperature side of the first Peltier element.
And the other end is bonded to the low temperature side of the second Peltier element.
By having a heat pipe, a cooling device, characterized by comprising a heat transfer path for connecting the container inner wall and the heating element. 2. The heating element is a CCD image pickup device.
The cooling device according to claim 1, wherein: