JPH0749266A - Infrared detector - Google Patents

Abstract

PURPOSE:To stabilize cooling temperature regarding the improvement of an infrared detector provided with a vacuum insulated container of Dewar structure and a Joule-Thomson type cooler. CONSTITUTION:An infrared detector is provided with a vacuum insulated container of Dewar structure including an inner cylinder 2 and an outer cylinder 4, an infrared detecting element 8 provided on the vacuum space side of the inner cylinder 2 in opposition to an infrared transmitting aperture 6 provided at the outer cylinder 4, and a Joule-Thomson type cooler 10 inserted into the inner cylinder 2. This infrared detector is further provided with a means for sealing the cooler inserted side of the inner cylinder 2 airtightly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an infrared detector provided with a vacuum insulation container having a dual structure and a Joule-Thomson type cooler.

[0002] An infrared detection element (photoelectric conversion element for infrared detection) made of a binary or ternary compound semiconductor is usually used in a state of being cooled to a liquid nitrogen temperature (77K). For this reason, in an infrared detector using this type of detection element, a vacuum heat insulation container having a dual structure consisting of an inner cylinder and an outer cylinder is used, and an infrared transmission window is provided in a part of the outer cylinder and a transmission window is provided. The sensing element is installed on the wall of the inner cylinder facing the, and a cooling means such as a Joule-Thomson type cooler is provided in the inner cylinder of the heat insulating container having such a configuration to cool the sensing element to a predetermined temperature and operate. The configuration is made to let.

In this type of infrared detector, when the temperature of the detecting element or the like changes, the output signal level also changes and a stable infrared image cannot be obtained, so that the cooling temperature of the detecting element is kept stable. Required.

[0004]

2. Description of the Related Art Conventionally, as shown in FIG. 5, a vacuum heat insulating container having a dual structure including an inner cylinder 2 and an outer cylinder 4 and an infrared transmitting window 6 provided in the outer cylinder 4 are opposed to each other. An infrared detector 12 including an infrared detection element 8 provided on the vacuum space side and a cooler 10 of the Joule-Thomson type inserted in the inner cylinder 2 is known.

In FIG. 5, reference numeral 14 denotes a high pressure gas introduction pipe for supplying a high pressure gas such as argon to the cooler 10.
Reference numeral 16 indicates a nozzle for discharging the high pressure gas supplied to the cooler 10. Reference numeral 18 is an infrared detector 1.
Reference numeral 20 denotes a cooler fixing metal fitting that supports the high-pressure gas introduction pipe 14, respectively.

[0006]

The Joule-Thomson type cooler 10 uses absorption of heat due to expansion when high-pressure gas is discharged from the nozzle 16 for cooling, and cleans the nozzle 16 and its vicinity. The degree directly affects the stable operation of the cooler 10. Therefore, conventionally, a high-purity gas is used as the high-pressure gas supplied to the cooler 10.

However, when the infrared detector 12 is not in operation, a gap between the infrared detector 12 and the substrate 18 or the substrate 18 and the cooler fixing bracket 20 are caused by a pressure difference between a portion of the inner cylinder 2 where the cooler 10 is inserted and the outside. Atmosphere may enter the inside of the inner cylinder 2 through the gap between them, and the stable operation of the cooler 10 may be hindered.

If the stable operation of the cooler 10 is hindered, the cooling temperature of the infrared detection element 8 becomes unstable, and the signal output of the detection element fluctuates, and the luminance of the signal output fluctuates when it is visualized. become.

Therefore, an object of the present invention is to stabilize the cooling temperature of the infrared detecting element and prevent the fluctuation of the luminance of the image due to the fluctuation of the output.

[0010]

According to the present invention, a vacuum heat insulating container having a dual structure including an inner cylinder and an outer cylinder, and a vacuum space side of the inner cylinder facing an infrared transmitting window provided in the outer cylinder. In an infrared detector comprising an infrared detecting element provided in and an Joule-Thomson type cooler inserted in the inner cylinder, the side of the inner cylinder in which the cooler is inserted is hermetically sealed. There is provided an infrared detector further comprising a means for

[0011]

In the infrared detector of the present invention, since means for hermetically sealing the side of the inner cylinder where the cooler is inserted is provided, dust in the atmosphere that has entered the inside of the inner cylinder from the outside and Moisture is prevented from hindering the stable operation of the cooler, and the cooling temperature of the infrared detection element is stabilized.

[0012]

EXAMPLES Examples of the present invention will be described below. FIG. 1 is a sectional view of an infrared detector showing a first embodiment of the present invention. Reference numeral 4 is an outer cylinder, reference numeral 6 is an infrared transmitting window made of germanium or the like sealed at the end of the outer cylinder 4, and reference numeral 2 is inserted into the outer cylinder 4 from the other end to the other end of the outer cylinder 4. Figure 3 shows a glass inner tube sealed in shape.

These outer cylinder 4, infrared transmitting window 6 and inner cylinder 2
The space defined by is evacuated to a vacuum. For example, the multi-element infrared detection element 8 is attached to the vacuum space side of the inner cylinder 2 so as to face the infrared transmission window 6.

A conductor pattern (not shown) made of gold or the like is formed on the side surface of the inner cylinder 2 on the vacuum space side, and each element output lead wire of the infrared detection element 8 is connected to one end thereof.

At the lower part of the outer cylinder 4, there is provided an annular disk type ceramic terminal plate 24 having a conductive pattern for individually leading the lead wires 22 connected to the other end of each conductor pattern to the outside of the outer cylinder 2. , Is provided so as to traverse the outer cylinder 4.

The getter 2 is placed in the vacuum space inside the outer cylinder 4.
6 is provided, and the getter 26 is provided via the lead wire 28.
Is driven, it is possible to deal with the deterioration of the degree of vacuum in the vacuum space.

The infrared detector 12 is fixed to a substrate 18 having an opening 18A at a position corresponding to the inner cylinder 2. On the surface of the substrate 18 opposite to the fixed surface of the infrared detector 12,
The cooler fixing metal fitting 20 through which the high-pressure gas introduction pipe 14 of the cooler 10 penetrates is fixed. The penetrating part of the high-pressure gas introduction pipe 14 in the cooler fixing bracket 20 is hermetically sealed with a metal brazing material or the like.

In this embodiment, a substantially circular groove 30 concentric with the inner cylinder 2 is provided on the substrate 18 side of the infrared detector 12.
An O-ring 34 made of rubber or the like is seated in the groove 30 to hermetically seal between the infrared detector 12 and the substrate 18. In addition, the cooler fixing bracket 20 of the substrate 18
A substantially circular groove 32 which is also concentric with the inner cylinder 2 is formed on the side of, and an O-ring 36 is seated in the groove 32,
The space between the substrate 12 and the cooler fixture 20 is hermetically sealed.

Further, in this embodiment, the cooler fixing bracket 2
An airtight valve 38 is provided at 0. The airtight valve 38 functions to allow the gas to flow from the inside to the outside of the inner cylinder 2 and to prevent the gas from flowing from the outside to the inside. A configuration example of the airtight valve 38 will be described later.

During operation of the infrared detector, a high pressure gas such as argon or nitrogen is supplied to the cooler 10 through the high pressure gas introduction pipe 14, and the supplied high pressure gas is discharged from the nozzle 16. The surrounding heat is absorbed by the adiabatic expansion when the high-pressure gas is released, and the infrared detection element 8 and the like are cooled.

The gas discharged from the nozzle 16 travels downward in the figure in the inner cylinder 2 through a gas flow passage (not shown) provided between the cooler 10 and the inner cylinder 2, and the airtight valve 38 is opened. Is released to the outside via.

When the infrared detector is not operating, the nozzle 16
No high-pressure gas is released from the. Therefore, the atmospheric pressure inside the inner cylinder 2 may become lower than the atmospheric pressure outside due to changes in the environmental temperature and the like.

In this embodiment, the infrared detector 12 and the substrate 1
8 is airtightly sealed by an O-ring 34, and the substrate 18 and the cooler fixing bracket 20 are airtightly sealed by an O-ring 36. Therefore, even if the inside of the inner cylinder 2 becomes lower than the atmospheric pressure of the outside, the atmosphere is prevented from flowing into the inner cylinder 2, and the nozzle 16 and the like are not contaminated.

Therefore, it is possible to stabilize the cooling temperature of the infrared detecting element during the operation of the infrared detector, and prevent the fluctuation of the image brightness due to the fluctuation of the signal output of the detecting element.

FIGS. 2 and 3 are sectional views of infrared detectors showing the second and third embodiments of the present invention, respectively.
In the second embodiment, in order to hermetically seal the side of the inner cylinder 2 where the cooler 10 is inserted, the O-rings 34 and 36 are seated in the grooves formed in the substrate 18 and the cooler fixing bracket 20, respectively. ing.

On the other hand, in the third embodiment of FIG. 3, the O-ring 34 'for hermetically sealing the space between the infrared detector 12 and the substrate 18 is not provided on the lower surface of the infrared detector 12,
The infrared detector 12 is seated in a groove formed on the side portion of the lower flange 12A. Accordingly, the infrared detector 12
The recess 40 for fitting the flange 12A of the
Is formed.

The second and third embodiments are the same as the first embodiment except for the position where the O-ring is provided. According to the second or third embodiment, the first
As in the embodiment, it is possible to prevent air from flowing into the inner cylinder 2 when the infrared detector is not operating, and to obtain a stable cooling temperature when the infrared detector is operating.

FIG. 4 is a sectional view showing a structural example of the airtight valve 38 in the embodiment described above. The airtight valve 38 includes a movable member 42, a spring 44, and an O ring 46.
The movable member 42 includes a small-diameter portion 42A that penetrates the air circulation hole 20A formed in the cooler fixing bracket 20, and a small-diameter portion 42A.
And large-diameter portions 42B and 42C formed at both ends of the. The diameters of the large diameter portions 42B and 42C are larger than the diameter of the air circulation hole 20A.

The spring 44 has a large diameter portion 42B on the inner cylinder side.
And the cooler fixing metal fitting 20 and urges the movable member 42 in the direction in which it extends. O-ring 46
Is provided on the cooler fixing metal fitting 20 side of the large diameter portion 42C.

According to this structure, when the infrared detector is not operating, the O-ring 46 is interposed between the large diameter portion 42C and the cooler fixing metal fitting 20 by the urging force of the spring 44, and the inside and outside are hermetically sealed. To be achieved. Also, when the infrared detector operates, the internal pressure becomes high, and the spring 44
The gas is released from the inside to the outside against the biasing force of.

As described above, by using the airtight valve as shown in FIG. 4, it is possible to allow the gas to flow from the inside of the inner cylinder to the outside and to prevent the gas from flowing from the outside to the inside. Become.

[0032]

As described above, according to the infrared detector of the present invention, the cooling temperature of the infrared detecting element can be stabilized. As a result, it is possible to prevent the luminance variation of the image due to the signal output variation of the infrared detection element.

[Brief description of drawings]

FIG. 1 is a sectional view of an infrared detector showing a first embodiment of the present invention.

FIG. 2 is a sectional view of an infrared detector showing a second embodiment of the present invention.

FIG. 3 is a sectional view of an infrared detector showing the third embodiment of the present invention.

FIG. 4 is a sectional view of an airtight valve according to each embodiment of the present invention.

FIG. 5 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 2 Inner cylinder 4 Outer cylinder 6 Infrared transmission window 8 Infrared detector 10 Joule-Thomson type cooler 12 Infrared detector 34, 34 ', 36, 46 O-ring 38 Airtight valve

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomofumi Ueda 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor, Koji Hirota 1015, Kamedotachu, Nakahara-ku, Kawasaki, Kanagawa Prefecture, Fujitsu Limited

Claims (3)

[Claims] 1. A vacuum heat insulating container having a dual structure including an inner cylinder (2) and an outer cylinder (4), and the inner cylinder (6) facing the infrared transmitting window (6) provided in the outer cylinder (4). In the infrared detector comprising the infrared detecting element (8) provided on the vacuum space side of 2) and the Joule-Thomson type cooler (10) inserted in the inner cylinder (2), An infrared detector further comprising means for hermetically sealing the side of the tube (2) in which the cooler (10) is inserted. 2. The infrared detector according to claim 1, wherein the infrared detector (12) is fixed to a substrate (18) having an opening (18A) at a position corresponding to the inner cylinder (2), A cooler fixing metal fitting (20) through which the high pressure gas introduction pipe (14) of the cooler (10) penetrates is fixed to the surface of the substrate (18) opposite to the fixing surface of the infrared detector (12), The means for hermetically sealing is an O-ring (3) seated in a substantially circular groove formed in at least one of the infrared detector (12), the substrate (18) and the cooler fixing metal fitting (20).
Infrared detector characterized by including 4,34 ', 36). 3. The infrared detector according to claim 2, wherein the cooler fixing bracket (20) has an airtight valve (38), and the airtight valve (38) is inside the inner cylinder (2). An infrared detector characterized in that it allows gas to flow from the outside to the outside and blocks the flow of gas from the outside to the inside.