JPH02266240A - Infrared detector - Google Patents

Abstract

PURPOSE:To reduce vibration which is generated from an expanding machine and to prevent a dewer from breaking by mounting a dynamic vibration absorber on the casing of the expanding machine. CONSTITUTION:When a refrigerator 3 begins operation, a displacer in the expanding machine 6 starts reciprocal motion. The operation frequency of the displacer is made coincident with the natural vibration frequency determined by the mass of a load mass 14 and the spring constant of a supporting spring 15. Further, the mass of the mass 14 is set to such a mass that a reciprocal motion inertial force nearly equivalent to the exciting force of the displacer is obtained. In this case, the inertial force of the mass 14 operates on the motion vibration absorber 12 on the casing 13 as the damping force, so the vibration generated by the expanding machine 6 can be reduced. Consequently, the breakage of the dewer 2 can be eliminated and the reliability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an infrared detection device that is mounted on a guided flying object, an infrared imaging device, or the like and detects infrared rays.

[Conventional technology]

FIG. 3 is a configuration diagram showing a conventional infrared detection device.

This infrared detection device is generally thick (divided into a Dual 2 with a built-in infrared detection element I and an infrared detection element 1).
and a refrigerator 3 for cooling the refrigerator. As the refrigerator 3, a refrigerator using a refrigeration cycle such as a reverse Stirling cycle or a Gifford McMahon cycle is often used, and FIG. 3 shows a refrigerator using a Stirling cycle as an example. The refrigerator 3 is composed of a pressure 12i machine 4, a connecting pipe 5, and an expander 6, and the expansion m6 is provided with an elongated cylindrical projection called a cold finger 7.
The structure is such that freezing occurs at the tip.

The dua 2 has a double-walled structure composed of an outer shell 8 and an inner shell 9. The infrared detecting element 1 is attached to the tip of the inner shell 9, and the outer shell 8 has a double wall structure. is provided with a window 10 that transmits infrared rays.

The space between the outer shell 8 and the inner shell 9 is kept in a vacuum to prevent heat from entering into the tips of the infrared detecting element 1 and the cold finger 7 from the outside. On the surface of the inner shell 9 facing the vacuum space, a vapor-deposited film or a metal film of a material with low emissivity such as aluminum or silver is formed, and the inner shell 9 is made of glass or the like. Made of material with low thermal conductivity. Reference numeral 11 denotes a thermal interface, and the thermal interface 11 is attached to the tip of the cold finger 7, and is configured to measure the difference in thermal expansion between the cold finger 7, which is generally made of metal, and the inner shell 9, which is generally made of glass. For example, a material that is elastic and has high 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. It is supposed to be done.

Next, the operation of the conventional device shown in FIG. 3 will be explained.

When the refrigerator 3 starts operating and begins to generate refrigeration at the tip of the cold finger 7, the infrared sensing element 1 receives heat from the refrigerator 3 via the thermal interface 11.
When the temperature drops to around 77, it begins to detect infrared rays that pass through the window 10.As described above, the dual 2 is provided on the surfaces of the outer shell 8 and the inner shell 9 facing each other. The vapor-deposited film or plating film with low emissivity and the inner shell 9 made of a material with low thermal conductivity reduce heat intrusion from the outside due to convection, radiation, and conduction, and reduce the load on the refrigerator 3. It is decreasing.

[Problem to be solved by the invention]

In the conventional infrared detection device as described above, the outer shell 8 and inner shell 9 of the Dua 2 are made of glass, which is a material with low thermal conductivity, and the expander 6 is connected to the expander 6 by adhesive or bolts. This caused problems such as sticking, making it impossible to maintain a vacuum between the outer shell 8 and the inner shell 9, and the duure 2 itself losing its function.

This invention was made in order to solve the above-mentioned problems, and aims to reduce the vibration generated from the expander, thereby preventing damage to the dua, and providing a highly reliable infrared detection device. purpose.

(Means for Solving the Problems) The infrared detection device according to the present invention is characterized in that a vibration absorbing means (dynamic vibration absorber 12) is attached to the casing 13 of the expander 6.

[Effect]

The vibration absorbing means (dynamic vibration absorber 12) generates a vibration damping force to offset the inertial unbalanced force of the reciprocating motion generated from the expander 6.

[Embodiments of the invention]

FIG. 1 is a block diagram of an infrared detection device according to an embodiment of the present invention, and the constituent elements shown in FIG. 3 are designated by the same reference numerals and their explanations will be omitted. In FIG. 1, reference numeral 12 denotes a dynamic vibration absorber as a vibration absorbing means attached to the casing of the expander 6. FIG. 2 is a sectional view showing details of the dynamic vibration reducer 12. In FIG. 2, 13 is the casing of the expander 6, 14 is a movably mounted load mass, and 15 is a casing of the expander 6.
16 is a bearing for moving the load mass 14 along the rod 17; and 18 is a casing of the dynamic vibration absorber 12.

Next, the operation will be explained. When the refrigerator 3 starts operating, a displacer (not shown here) inside the expander 6 starts reciprocating motion.

The operating frequency fd of this displacer and the load mass 14
The mass of the load mass 14 is made to match the spring constant of the support spring 15 with the natural frequency f determined by the and the mass of the load mass 14 is a mass that can obtain a reciprocating force approximately equivalent to the excitation force of the displacer. If set, this 11. Since the inertial force of the load mass 14 acts as a damping force on the casing 13, vibrations generated in the expander 6 can be extremely reduced. As a result, it is possible to eliminate damage to the dual unit and obtain a highly reliable infrared imaging device.

Although the above embodiment describes an expander for an infrared imaging device using a reversed Stirling cycle, it may also be an expander for an infrared imaging device using a Gifford-McMahon cycle, and in this case, the same procedure as in the above embodiment can be applied. It has a great effect.

(Effects of the Invention) As described above, according to the present invention, the vibration absorbing means is attached to the casing of the expander, so vibration damping is performed to offset the inertial unbalanced force of the reciprocating motion generated from the expander. A force is generated, and the vibration generated in the expander can thereby be extremely reduced. As a result, damage to the dua is prevented and reliability is improved.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a main part of an infrared detection device according to an embodiment of the present invention, FIG. 2 is a sectional view of a main part of a dynamic vibration absorber in FIG. 1,
FIG. 3 is a block diagram of the main parts of a conventional infrared detection device. DESCRIPTION OF SYMBOLS 1... Infrared detection element, 2... Dual, 3... Refrigerator, 4... Compressor, 5... Connecting pipe, 6... Expander, 12... Dynamic vibration absorber (vibration absorption means), 13...casing of the expander. Agent Masu Oiwa A (and 2 others) 1B;

Claims (1)

[Claims] An infrared detection device comprising a dua incorporating an infrared detection element, a refrigerator for cooling the infrared detection element, a compressor built in the refrigerator, and an expander connected to the compressor by a connecting pipe. An infrared detection device characterized in that a vibration absorbing means is attached to the casing of the expander.