JPH05248941A - Thermoelectric cooling type infrared ray sensor - Google Patents

Abstract

PURPOSE:To provide a thermoelectric type infrared ray sensor to prevent vacuum destruction inside of the case. CONSTITUTION:A thermoelectric type infrared ray sensor is provided, on the base 14 of a package 14, with a thermoelectric element 16 which is formed by pinching a plurality of semiconductor blocks 30a-30c generating Peltier effect between insulative boards 28a-28d, and an infrared ray sensor 22 is mounted on the thermoelectric element 16, and this sensor 22 and a thermoelectric element 16 are installed sealedly in the case 18 of the package having an infrared ray transmission window 20. Ring-shaped grooves 21, 19 are formed at the surface in the neighborhood of the periphery of the window 20 and at the surface in the neighborhood of the window fitting part of this case 18, and a ring- shaped sealing member 34 having a ridge 34a mating with the grooves 19, 21 is installed in an area over the case 18 and window 20 by fitting the ridge 34a in the grooves 19, 21.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to improvements in electronically cooled infrared detectors. Infrared detectors (photoelectric converters for infrared detection) that are generally made of binary or ternary compound semiconductors
Are used in the cooled state to obtain the desired sensitivity characteristics.

As a cooling means, one using a refrigerant such as liquid nitrogen or liquid argon, one using a Joule-Thomson cooler using a high pressure gas such as argon or nitrogen,
There are a refrigerator using a compressor and an electronic cooling element utilizing the Peltier effect.

The cooling by the electronic cooling element of (3) is excellent in outdoor usability without the need for replenishing the cooling source as in (1), and is cheaper in price compared with (2), so that it is mainly used for infrared image pickup devices for consumer use. It is used. However, the electronic cooling element has a lower cooling capacity than other means, and it is required to reduce the heat load.

[0004]

2. Description of the Related Art Conventionally, an electronic cooling type infrared detector is provided in which a thermoelectric cooling element is provided on a base of a package, an infrared sensor is mounted on the thermoelectric cooling element, and the infrared sensor is cooled to a desired temperature to obtain sensitivity. It has been known.

This conventional electronic cooling type infrared detector is shown in FIG.
Will be described. The infrared detector 12 is packaged, and has a package base 14 to which a Peltier element 16 as an electronic cooling element is fixed on the upper surface, and a Kovar package that seals the base 14 by welding or the like so as to cover the Peltier element 16. Case 18 and case 18
And an infrared transmission window 20 made of sapphire or the like fused to the upper part of the.

An infrared sensor 22 facing the infrared transmission window 20 is mounted on the electronic cooling element 16. Reference numeral 24 denotes a lead terminal provided so as to penetrate the case 18 and having a gold pattern formed on a ceramic substrate. The infrared sensor 22 and the lead terminal 24 are connected by a gold bonding wire 26.

The space defined by the base 14, the case 18 and the infrared transmitting window 20 is evacuated to a vacuum in order to prevent icing and reduce the temperature reached by the cooling, whereby the infrared sensor 22 is passed through this space. It is difficult for heat to flow into.

The Peltier element 16 includes a ceramic stage 28a, a plurality of semiconductor blocks 30a having a Peltier effect, a ceramic stage 28b, a plurality of semiconductor blocks 30b having a Peltier effect, a ceramic stage 28c, and a plurality of Peltier effects. The semiconductor block 30c and the ceramic stage 28d are laminated in this order from the lower side to have a three-stage configuration.

Each semiconductor block is made of, for example, BiTe, and these are connected in series so that a current flows in a predetermined direction. As a result, each ceramic stage is cooled stepwise, the temperature of the uppermost ceramic stage 28d to which the infrared sensor 22 is fixed becomes the lowest, and the infrared sensor 22 can be cooled to approximately 200K.

[0010]

As described above, the infrared transmitting window 20 is fused to the case 18 made of Kovar. Therefore, when a vacuum break (leak) occurs in the fusion bonding portion 32, there is a problem that the infrared sensor 22 is frozen, or the temperature reached by cooling rises and the infrared sensor cannot be cooled to a desired temperature.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electronic cooling type infrared detector capable of preventing the occurrence of vacuum break inside the case. That is.

[0012]

In order to solve the above-mentioned problems, the present invention provides an electronic cooling element constituted by sandwiching a plurality of semiconductor blocks which produce a Peltier effect between insulating substrates on the base of a package. In an electronic cooling type infrared detector in which an infrared sensor is mounted on the electronic cooling element, and the infrared sensor and the electronic cooling element are sealed in a case of a package having an infrared transparent window, the outer peripheral part of the infrared transparent window. An annular groove is formed on each of the adjacent surface and the window mounting portion adjacent surface of the case, and an annular sealing member having an annular protrusion corresponding to the annular groove is fitted into the annular groove, and the case and Provided is an electronic cooling type infrared detector characterized by being mounted over an infrared transmitting window.

As an alternative, the inert gas may be sealed in the case at 1 atm or more, and the infrared ray transmitting window may be attached to the case from the inside of the case. Also in the case of this alternative, an annular groove is formed on each of the rear surface near the outer peripheral portion of the infrared transmitting window and the rear surface near the window mounting portion of the case, and the annular sealing member having the annular projections corresponding to the annular groove is formed on the annular projection. Is fitted in the annular groove, and is preferably mounted from the inside of the case to the case and the infrared transmitting window.

[0014]

[Function] Since the joint between the case and the infrared transmitting window is not flat, but the ring-shaped projection is fitted in the ring-shaped groove, the leak path between the inside of the case and the outside air can be lengthened, and the risk of vacuum breakage. Can be reduced.

Further, when the inert gas is sealed in the case at 1 atm or more and the infrared transmitting window is attached to the case from the inside of the case, the infrared transmitting window is always pressed against the case from the inside of the case. The risk of vacuum break can be reduced.

[0016]

Embodiments of the present invention will now be described in detail with reference to the drawings. In the description of the embodiments, components that are substantially the same as those of the conventional device shown in FIG. 5 are designated by the same reference numerals, and part of the description thereof is omitted.

First, the configuration of the first embodiment of the present invention will be described with reference to FIGS. This first embodiment is
It differs from the conventional example shown in FIG. 5 in the following points, and other configurations are substantially the same.

That is, as shown in the enlarged sectional view of the portion A of FIG. 2, an annular groove 21 is formed on the surface of the infrared transmitting window 20 in the vicinity of the outer peripheral portion thereof.
And the annular groove 19 is also formed on the surface of the Kovar case 18 in the vicinity of the infrared transmission window mounting portion.

Then, the Kovar annular sealing member 34 having the annular projections 34a corresponding to the annular grooves 19 and 21 is fitted into the annular grooves 19 and 21 to form the case 18 and the infrared transmitting window 20. Attach by fusing or gluing over.

As a result, the case 18 is evacuated to a vacuum.
The leak path between the inside and the outside air can be long, and the risk of vacuum breakage (leakage) can be greatly reduced.

Next, referring to FIGS. 3 and 4, the second embodiment of the present invention will be described.
The configuration of the embodiment will be described. This embodiment is different from the conventional example in the points described below, and the other components are substantially the same as the conventional example shown in FIG.

That is, in this embodiment, a gas having a low thermal conductivity (for example, A
r, Kr, Xe, Cl ₂ ) is sealed at 1 atm or more, and the infrared transmitting window 20 is attached to the case 18 from the inside.

The thermal conductivity of the above-mentioned gas is as follows. Ar: 1.24 W / cm · K, Kr: 0.65 W / cm · K, Xe: 0.39 W / cm · K, Cl ₂ : 0.54 W / cm · K Gas with low thermal conductivity Since the enclosure is sealed inside the case, the achieved cooling temperature slightly rises as compared with the case of vacuum, but since the infrared transmission window 20 is strongly pressed against the case 18 from the inside, the risk of leakage is reduced.

As shown in the enlarged cross-sectional view of the portion A in FIG. 4, it is desirable to construct the joint portion of the infrared transmitting window 20 and the case 18 in this embodiment as in the first embodiment. That is, the annular groove 21a is formed on the rear surface near the outer peripheral portion of the infrared transmitting window 20, and the annular groove 19a is also formed on the rear surface near the infrared transmitting window mounting portion of the Kovar case 18.

The Kovar annular sealing member 36 having the annular protrusion 36a corresponding to the annular grooves 19a and 21a.
The ring-shaped projection 36a is fitted into the ring-shaped grooves 19a and 21a, and is attached by fusion or adhesion from the inside of the case 18 to the case 18 and the infrared transmitting window 20.

[0026]

Since the present invention is configured as described in detail above, the risk of vacuum breakage can be greatly reduced, which prevents the infrared sensor from freezing due to vacuum break and the ultimate cooling temperature. It is possible to achieve the effect of preventing the rise of

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a portion A of FIG.

FIG. 3 is a sectional view of a second embodiment of the present invention.

FIG. 4 is an enlarged sectional view of part A of FIG.

FIG. 5 is a sectional view of a conventional example.

[Explanation of symbols]

 14 Base 16 Peltier Element 20 Infrared Transmission Window 22 Infrared Sensor 34,36 Kovar's Annular Sealing Member

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomofumi Ueda 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa, Fujitsu Limited

Claims (3)

[Claims] 1. An insulating substrate on the base (14) of the package.
An electronic cooling element (16) configured by sandwiching a plurality of semiconductor blocks (30a to 30c) that generate a Peltier effect between (28a to 28d) is provided, and an infrared sensor (22) is mounted on the electronic cooling element (16). In addition, in the electronic cooling type infrared detector in which the infrared sensor (22) and the electronic cooling element (16) are sealed in a package case (18) having an infrared transparent window (20), the infrared transparent window (20 ) Surface near the outer peripheral portion and the case
An annular groove (21, 19) is formed on the surface near the window mounting portion of (18), and an annular sealing member (34) having an annular protrusion (34a) corresponding to the annular groove (19, 21) is provided. Insert the annular protrusion (34a) into the annular groove (19,2
1), and then the case (18) and infrared transparent window (2
An electronically cooled infrared detector characterized by being installed over 0). 2. An insulating substrate on the base (14) of the package.
An electronic cooling element (16) configured by sandwiching a plurality of semiconductor blocks (30a to 30c) that generate a Peltier effect between (28a to 28d) is provided, and an infrared sensor (22) is mounted on the electronic cooling element (16). In addition, in the electronic cooling type infrared detector in which the infrared sensor (22) and the electronic cooling element (16) are sealed in a case (18) of a package having an infrared transmission window (20), the inside of the case (18) A gas having a low thermal conductivity is sealed in the case at 1 atm or more, and the infrared transmission window (20) is provided inside the case (18).
Electronic cooling type infrared detector characterized by being attached to (18). 3. An annular groove (21a, 1a, 1a, 1a, 1a
9a), and an annular sealing member (36) having an annular protrusion (36a) corresponding to the annular groove (19a, 21a) is fitted into the annular groove (19a, 21a). The electronically cooled infrared detector according to claim 2, characterized in that the thermoelectrically cooled infrared detector is attached from the inside of the case (18) to the case (18) and the infrared transmission window (20).