JPH0632588Y2 - Infrared detector - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention uses an infrared detection element mounted on, for example, an infrared imaging device and used by cooling to a very low temperature of, for example, about 80 K such as HgTdTe or InSb. Regarding infrared detectors.

[Conventional technology]

FIG. 2 is a view showing a conventional infrared detector. The infrared detector is generally divided into a dual (2) having a built-in infrared detecting element (1) and an infrared detecting element (1) at an extremely low temperature, for example, 80K.
It is composed of a refrigerator (3) for cooling back and forth. As the refrigerator (3), a refrigerator utilizing a Stirling cycle or a Gifode McMahon cycle is often used, and FIG. 2 shows a refrigerator utilizing a Stirling cycle as an example. The refrigerator (3) is composed of a compressor of (4), an expander of (5) and a connecting pipe of (6), and the expander (5) has an elongated cylindrical shape called a cold finger (7). Protrusions are provided, and the structure is such that freezing is generated at the tip of the cold finger (7).

The dual (2) has a double wall structure composed of an outer shell (8) and an inner shell (9), and the infrared detecting element (1) is provided at the tip of the inner shell (9). A window (10) attached to the outer shell (8) for transmitting infrared rays
Is provided. The space between the outer shell (8) and the inner shell (9) is kept in a vacuum so that heat does not enter from the outside to the tips of the infrared detection element (1) and the cold finger (7). (8) and the surface of the inner shell (9) facing the vacuum space is formed with a vapor deposition film or a plating film of a substance having a low emissivity such as aluminum or silver, and the inner shell (9)
Is made of a material with low thermal conductivity. (1) is a thermal interface, the thermal interface (11)
Is attached to the tip of the cold finger (7) and is generally made of metal, for absorbing the dimensional change due to the difference in the coefficient of thermal expansion between the cold finger (7) and the inner shell (9), For example, an object having elasticity and large thermal conductivity such as laminated copper foil is used, and its tip is always in close contact with the bottom surface of the inner shell (9). (12) is an O-ring and is the cold finger
The space between the inner shell (9) of (7) is airtight to the outside and is fastened by several screws (13).

Next, the operation of the conventional device shown in FIG. 2 will be described. When the refrigerator (3) starts to operate and freezing occurs at the tip of the cold finger (7), the infrared detection element (1) draws heat to the refrigerator (3) via the thermal interface (11). When the temperature drops to about 80K, infrared rays transmitted through the window (10) are converted into electric signals. As described above, the dual (2) is provided on the vacuum layer provided between the outer shell (8) and the inner shell (9) and on the surfaces of the outer shell (8) and the inner shell (9) facing each other. A vapor deposition film or plating film with a low emissivity and an inner shell (9) made of a material with a low thermal conductivity reduce the heat intrusion from the outside due to convection, radiation and conduction, and the load on the refrigerator (3) Has been reduced.

Further, the O-ring (12) makes the space between the cold finger (7) and the inner shell (9) airtight to the outside to prevent the inflow of air from the outside. As a result, the cooling effect is prevented from being lost to the liquefied latent heat of air from the outside, and the load on the refrigerator (3) is reduced.

[Problems to be solved by the device]

The conventional infrared detector as described above has the following problems.

That is, the inner shell (9) has often been made of glass as a material having a low thermal conductivity. However, glass is a material that is vulnerable to external forces such as impact and is easily broken.

Therefore, it is possible to use metal as an alternative to glass in order to mount it on equipment such as aircraft that generates high impact. However, even if the thermal conductivity of metal is small, it is 10 to 20 times larger than that of glass, and therefore it is necessary to reduce the thickness of the inner shell (9).

In an infrared detector using such a metal inner shell (9), the resonance frequency is low during vibration because the inner shell (9) is thin, and the resonance magnification that indicates the magnitude of the resonance displacement at that time is low. , The damping rate is small because it is only the damping inside the metal material of the inner shell (9), and the damping rate and the resonance magnification are inversely proportional. As a result, the resonance magnification becomes large and the displacement of the inner shell (9) is growing. Therefore, there was a problem that the displacement of the infrared detecting element (1) at the tip was large and the performance was deteriorated.

The present invention has been made to solve the above problems, and an object thereof is to obtain an infrared detector having high vibration resistance and shock resistance.

[Means for Solving the Problems]

The infrared detector according to the present invention has a friction coefficient material having a large friction coefficient inserted between the cold finger and the inner shell.

[Action]

In this invention, a friction coefficient material with a large friction coefficient is inserted between the outer diameter of the cold finger and the inner diameter of the inner shell and at the root position of the inner shell, and the energy generated at resonance is transferred between the inner shell and the friction coefficient material. The resonance energy is attenuated by changing the friction energy between them, and the resonance magnification is reduced to reduce the displacement of the infrared detection element (1) and eliminate the deterioration of performance.

〔Example〕

FIG. 1 is a diagram showing an embodiment of the present invention. In the figure, (1) to (13) have exactly the same configuration as the conventional device shown in Fig. 2, but the outer diameter of the cold finger (7) and the inner shell
A friction coefficient material (14) having a large friction coefficient is inserted between the inner diameters of (9) and at the root position of the inner shell, and the support pipe (16) is bonded with an adhesive (15) to the support pipe (16). Inner shell
It is fixed by being sandwiched between (9) and cold finger (7).

As the friction coefficient material (14), asbestos or rubber, which has a high friction coefficient and a low thermal conductivity, is used. Inserting the friction coefficient material (14) at the root position of the inner shell (9) causes the largest bending stress due to vibration at the root part, and by inserting the friction coefficient material (14) there, the energy is attenuated. This is to make it larger. The reason why the material with a large friction coefficient is used is to increase the friction energy with the inner shell (9). Inner shell friction coefficient material (14)
By using only the root part of (9), it is possible to reduce the amount of heat penetration from the friction coefficient material (14) to the infrared detection element (1). The support pipe (16) is made of a material having a high rigidity in order to securely support the friction coefficient material (14) and a small thermal conductivity in order to reduce the amount of heat intrusion.

In the infrared detector configured as described above, when vibration is applied, the energy at resonance is consumed by the friction energy between the inner shell (9) and the friction coefficient material (14) to attenuate the resonance energy. The resonance magnification becomes smaller and the displacement of the inner shell (9) becomes smaller. Therefore, the displacement of the infrared detection element (1) at the tip is also small, and it is possible to prevent the deterioration of performance.

[Effect of device]

As described above, this device has a simple structure in which a friction coefficient material having a large friction coefficient is inserted between the cold finger and the inner shell to detect an infrared ray detecting element during vibration (1).
It has the effect of suppressing the displacement of and preventing the deterioration of performance.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing a conventional infrared detector. In the figure, (1) is an infrared detector, (3) is a refrigerator, (7)
Is a cold finger, (8) is an outer shell, (9) is an inner shell, (14) is a friction coefficient material, (15) is an adhesive, and (16) is a support pipe. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Scope of utility model registration request] 1. A refrigerator having a tubular cold finger whose tip has a low temperature, an inner shell made of metal and having a hole-shaped space into which the cold finger is inserted, and an inner shell of the inner shell. An outer shell that covers the outside and forms a vacuum layer between the inner shell and the outer shell, an infrared detection element attached to the inner shell, and asbestos or rubber provided between the cold finger and the inner shell. An infrared detector comprising a friction coefficient material. 2. The infrared detector according to claim 1, wherein the friction coefficient material is provided at a base position of the inner shell.