JPH09162379A - Cooled ccd camera apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid dewing the surface of a CCD element. SOLUTION: A CCD camera apparatus comprises a glass 9, radiation vessel 7, Peltier effect element 26, thermally conductive metal 4 and CCD element 1 disposed in a package 2 contacted with the metal 4 having a window. The CCD element is held at a temp. over 0 deg.C and package 2 held at a temp. lower than 0 deg. specified time enough to dew with air in the vessel 7 and then the element 1 is dewed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present description relates to a cooled CCD camera device for cooling a CCD camera or the like.

[Prior Art] A charge coupled device (hereinafter referred to as a CCD) is widely used as a solid-state image pickup device. However, CCD has a characteristic that if the output current is zero even if there is no light input. However, there is a dark current in which a minute current flows, and the dark current depends on the temperature, and it is generally known that the value becomes about half as the temperature decreases by 8 ° C. When this dark current increases, the dynamic range of the signal decreases, the noise generated by the dark current increases, and the S /
The N ratio is lowered. Conventionally, in order to solve this problem, by using an electronic cooling element such as a Peltier effect element, C
A structure is adopted that cools the CD to reduce the dark current. FIG. 5 is a sectional view showing a schematic configuration of a conventional cooled CCD image pickup camera. The CCD element 21 is housed in a package 22 made of ceramic or metal. Package 2
Reference numeral 2 is in close contact with the heat absorbing joint portion (cold side) 24 of the Peltier effect element 23. The heat radiation joint portion (hot side) 25 of the Peltier effect element 23 is in close contact with a heat radiation container 26 having good heat conduction such as aluminum. The heat dissipation container 26 is provided with a glass window 27 and has a closed structure. The closed radiating container 7 contains the atmosphere such as air. Conventionally, with such a structure, the Peltier effect element 23 allows the CCD element 2
When 1 is cooled to a negative temperature of 0 ° C. or lower, the atmosphere 28 in the heat dissipation container 26 is cooled by the surface temperature of the CCD element 21, and the surface of the CCD element 21 is condensed as water to cause an image pickup problem. It was

[PROBLEMS TO BE SOLVED BY THE INVENTION] It is an object of the present invention to provide a cooling method and structure for preventing condensation of a CCD element in a cooled CCD camera or the like.

[Means for Solving the Problems] As a method for cooling a CCD element chip, the present invention uses a Peltier effect element and utilizes the thermal resistance between the CCD element and the package of the CCD element to keep the package portion at 0 ° C. The following is to keep the CCD element at 0 ° C or higher, allow the moisture in the air in the closed container to condense on the package part and the heat-conducting metal fittings, and allow the inside of the closed container to dry sufficiently before lowering the CCD element to a negative temperature. This is to prevent condensation on the surface of the CCD element.

[Embodiment] An embodiment is shown in FIG. 1, FIG. 2, FIG. 3, and FIG. FIG. 1 is a sectional view showing a schematic structure of a cooling type CCD camera device according to an embodiment of the present invention. FIG. 2 shows the CCD element 1, the package 2, and the heat conduction metal fitting 4.
It is the figure which looked at from the top. FIG. 3 is a view of a contact surface of the heat conducting metal fitting 4 with the package 2. This invention is a CCD
A heat conducting metal fitting 4 made of a metal such as aluminum having good heat conduction is closely attached to the package 2 of the element 1 and the CCD element 1. The heat conduction metal fitting 4 is in close contact with the heat absorption joint portion (cold side) 6 a of the Peltier effect element 6. The heat dissipation joint (hot side) 6 b of the Peltier effect element 6 is in close contact with the heat dissipation container 7. The heat dissipation container 7 is composed of a heat dissipation fin 8, an O (o) ring 10, a glass 9 and a lens fitting 11, and forms a hermetically sealed container. The CCD element 1 is a solid-state image sensor, and is housed in a package 2 made of ceramic, plastic, metal, or the like. The package 2 is connected to the printed circuit board 3 via the lead wire of the package 2. A circuit for driving the CCD element 1 is mounted on the printed circuit board 3. The heat conduction metal fitting 4 is made of a metal such as aluminum having good heat conduction, and is in close contact with the package 2 at a contact surface 4a having a larger window than the CCD element 1. The Peltier effect element 6 is a semiconductor element having a heat absorption junction (cold side) 6a and a heat dissipation junction (hot side) 6b due to the Peltier effect, and is generally known as an electronic refrigeration element. The heat dissipation container 7 is made of a metal having good heat conduction such as aluminum and has heat dissipation fins 8 for dissipating heat to the atmosphere. It has a structure that radiates heat to the atmosphere. Further, the heat dissipation container 7 has a closed chamber structure by a glass 9 that transmits light, an O (O) ring 10 made of a material such as rubber, and a glass pressing member 11. Light transmitted from the subject through the glass 9 reaches the CCD element 1 and is converted into an electric signal by a circuit mounted on the printed circuit board 3. The Peltier effect element 6 cools the package 2 from the heat absorbing joint 6 a through the heat conducting metal fitting 4. Package 2
Is cooled from the contact surface 4a of the heat-conducting metal fitting 4, and the entire package 2 is cooled after a certain time due to the thermal resistance of the package 2. The package 2 is the CCD element 1.
To cool. At this time, a temperature difference occurs between the package 2 and the CCD element 1 due to the thermal resistance of the material of the package 2. FIG. 4 is a graph of the relationship between temperature and time. C
The temperature 12 of the CD element 1 and the temperature 13 of the package 2 are shown. In a specific example, the outside air temperature is 25 ° C. At time t1, the Peltier effect element 6 is energized, and the endothermic junction 6
a is cooled, and the package 2 is cooled through the joint surface 4a of the heat-conducting metal fitting 4, and becomes about -1 degreeC at the time t2. At this time, the CCD element 2 is gradually cooled toward the CCD element 1 from the joint surface of the package 2 near the joint surface 4a. Due to the heat absorption in the container and the heat generated by the electric power of the CCD element 2 itself, the temperature becomes higher than the vicinity of the package 2 on the joint surface 4a and becomes about 1 ° C. Time t
The temperature of 2 is maintained by the power control of the Peltier effect element 6 from about 1 minute to about 30 minutes until time t3.
The temperature of the package 2 is about −1 ° C. from the time t2 to the time t3. Since the temperature of the heat-conducting metal fitting 4 is lower than -1 ° C and the temperature of the heat-absorption joint 6a of the Peltier effect element 6 is even lower, the moisture-containing atmosphere 5 in the heat dissipation container 7 has a negative temperature. , The heat conduction metal fitting 4 and the package 2 near the joint surface 4a are condensed as water drops. The atmosphere 5 in the heat dissipation container 7 is in a dry state. Atmosphere 5
After a sufficient time (t3−t2) for the Peltier effect element 6 to be dried, the Peltier effect element 6 is power-controlled and further cooled, and the CCD element 1 is cooled to the heat parallel state at t4. The temperature values shown in the graph of FIG. 4 vary according to the thermal resistance of the material of the package, and are only examples. Therefore, the numerical values such as the temperatures described with reference to FIG. 4 are merely examples. In summary, the moisture-containing atmosphere in the closed heat dissipation container 7 is condensed on the Peltier effect element 6, the heat conduction metal fitting 4, and the package 2 in the negative temperature portion, and the atmosphere in the heat dissipation container is sufficiently moisture. Is removed and it becomes dry. Even if the temperature of the Peltier effect element 1 is lowered to a negative temperature after the dry state as described above, the atmosphere 5 in the heat dissipation container 7 is dry air, so that no condensation occurs on the Peltier effect element 1.

[Effects of the Invention] The atmosphere 5 in the heat dissipation container 7 becomes dry air because moisture is condensed on the Peltier effect element 6, the heat conduction metal fitting 4, and the package 2, and the CCD element 1 can be cooled to a negative temperature without condensation and is dark. Since the current can be reduced, S
An image with a good / N ratio can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of the present invention,

[FIG. 2] is a top view of the relationship between the CCD device 1, the package 2, and the heat conduction metal fitting 4,

[Fig. 3] is a contact surface of the heat conducting metal fitting 4 with the package 2.

FIG. 4 is a graph of temperature and time.

[Explanation of symbols]

1: CCD device 2: Package 3: Printed circuit board
4: Heat conduction metal fittings 5: Atmosphere 6: Peltier effect element 7: Heat dissipation container
8: Fin 9: Glass 10: O (O) ring 11: Holding metal fitting 12: Peltier effect element 13: Package 14-20: No number used 21:
CCD element 22: Package 23: Peltier effect element 24: Endothermic junction 25: Heat dissipation junction 26: Heat dissipation container 27: Glass 2
8: Atmosphere

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] March 29, 1996

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Fig. 5

[Correction method] Change

[Correction contents]

FIG. 5 is a sectional view of a conventional cooled CCD imaging camera.

Claims (2)

[Claims] 1. A cooling type CC which comprises a glass 9, a heat dissipation container 7, a Peltier effect element 6, a heat conduction metal fitting 4 and a CCD element 1 of a package 2 and which is provided with a joint surface 4a of the heat conduction metal fitting 4.
D camera device. 2. The atmosphere 5 in the radiant heat container 7 is kept for a period of time (t3-t).
After dew condensation in 2), the CCD element 1 is cooled to a negative temperature.