JP2722203B2 - Infrared detector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared detection element used for non-contact measurement of the temperature of an object.

[Conventional technology]

Infrared detection devices that measure the temperature of an object or the like in a non-contact manner include a thermal type and a quantum type, and the thermal type detects infrared radiation emitted by the object. There are a type that converts the amount of heat of the absorber to be absorbed into heat electromotive force (thermopile) and a type that detects a change in resistance according to the amount of heat of the absorber (thermistor bolometer).

Usually, these thermal infrared detection devices are often used in a state where they are attached to a header and covered with a cap, and so that only infrared rays (heat rays) of the light rays emitted from the object reach the device. In many cases, the device has a structure in which an infrared transmission filter is disposed in a light passage, and a device has a black body in which an absorber that absorbs infrared light is formed of metal black or the like.

FIG. 6 shows the structure of an example of such a conventional infrared detecting element.

In the figure, 1 is a header, 2 is a thermal infrared detecting device attached to the header 1, 21 is a black body that absorbs infrared light of the device 2, 3 is a cap, 4 is an opening, and 5 is an infrared transmitting filter.

The black body portion 21 of the thermal type infrared detecting device 2 attached to the header 1 absorbs infrared rays emitted from the object to be detected, which is transmitted through the infrared transmitting filter 5 from the opening 4, and generates a thermoelectromotive force due to the amount of heat generated. The temperature of the detected object is detected by a change in resistance or the like.

[Problems to be solved by the invention]

In the conventional infrared detecting element having the above structure, for example, those having an incident angle as shown in FIG.
Some infrared rays that have passed through the cap opening 4 are not absorbed by the black body part 21, resulting in a problem in terms of sensitivity.

Further, those having an incident angle as shown in (b) in the figure are reflected on the inner wall of the cap 3 and absorbed by the black body part 21, so that the field of view of the black body part 21 is extremely wide, and In some cases, infrared rays may be absorbed. Further, since most of the inner wall of the cap 3 is within the field of view of the black body 21, when the temperature of the inner wall of the cap 3 rises, the black body 21 is not detected. There is a problem that an accurate value cannot be obtained due to an increase in the temperature of the inner wall of the cap 3 in addition to an increase in the amount of heat from the body.

The present invention has been made in order to solve the above-described problems, and has an object of providing an object which has good sensitivity, is less affected by infrared rays other than infrared rays emitted by an object, and can obtain an accurate value. And

[Means for solving the problem]

In order to achieve the above object, the present invention provides a thermal type infrared detecting device attached to a header, wherein a black body portion of the thermal infrared detecting device captures infrared light transmitted through an infrared transmitting filter from an opening at the top of the cap and radiates infrared light emitted from the object. In the infrared detecting element, the infrared transmitting filter is formed of a columnar or prismatic infrared transmitting crystal, the top surface of the column or prism is disposed in the opening at the top of the cap, and the bottom surface is at the top of the black body. In addition to the structure extending to the vicinity, the side surface of the cylindrical or prismatic shape is covered with a film that reflects infrared rays.

〔Example〕

 FIG. 1 shows an embodiment of the present invention.

In the figure, 1, 2, 21, 3 and 4 indicate the same or corresponding parts as those in FIG. 6, and reference numeral 5a denotes a columnar infrared transmitting filter made of an infrared transmitting crystal. It is held so that the bottom portion is very close to the black body portion 21, and the side portion is coated with a film 55 having a high reflectance such as Au.

The infrared ray (c) incident from the top surface of the infrared transmission filter 5a does not go out of the side surface portion, and all the incident light is absorbed by the black body portion 21.

Further, the interval between the filter 5a and the black body
The inner wall of the cap hardly enters the field of view of 21.

Further, as shown in FIG.
In the case where is configured such that the top surface on which light is incident protrudes from the cap opening 4, the field of view can be greatly narrowed by the coating on the peripheral surface of the filter 5b, and more accurate detection can be performed.

Also, as shown in FIGS. 3 and 4, when the infrared transmitting filters 5c and 5d are formed to have a projection around the opening 4 of the cap 3, the mounting of the infrared transmitting filters 5c and 5d becomes easy. Become.

FIG. 5 shows a method of manufacturing the infrared transmitting filters 5c and 5d having the structure shown in FIGS.

SiO ₂ films 51 and 52 are formed on both surfaces of a double-sided mirror-polished silicon wafer 50, a part of the film 51 is opened, and a scribe line 53 is dug shallowly by etching [FIG. Next, a hole having a predetermined width is formed in the film 52, and etching is performed to a desired depth while covering the film 51 side, thereby forming a groove 54 (FIG. (B)). In the completed state, an infrared reflective film 55 is formed by vertical vapor deposition of Cr / Au or the like (FIG. (C)), and the films 51 and 52 are removed by etching (FIG. (D)). By scribing, infrared transmission filters 5c and 5d can be easily obtained.

When deep etching is performed by a reactive ion etching method using CCl ₂ F ₂ or the like, the filter shape can be cylindrical or prismatic. In the case of using an etchant composed of ethylenediamine, pyrocatechol, and water, the plane anisotropy of an etchant with respect to Si is used, and when a (110) plane or the like is used, a prism is easily formed.

〔The invention's effect〕

As described above, according to the present invention, all the infrared rays that have entered the infrared transmitting filter are absorbed by the black body part, so that the sensitivity is improved, and the inner wall of the cap is almost completely in view of the black body part. There is the effect that the light is hardly penetrated, the field of view through the infrared transmission filter of the black body portion is narrow, infrared light from other than the object is hardly absorbed, and accurate detection can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one embodiment of the present invention, FIG.
FIG. 4 is a schematic view showing another embodiment of the present invention, FIG. 5 is a cross-sectional view showing a method of manufacturing an infrared transmitting filter having the structure shown in FIGS. 3 and 4, and FIG. It is a schematic diagram which shows the structure of an example of this kind of infrared detecting element. 1 ... header, 2 ... thermal infrared detection device, 21 ...
Black body, 3 ... Cap, 4 ... Opening, 5, 5a, 5b, 5c, 5
d: infrared transmission filter, 55: reflection film. In the drawings, the same reference numerals indicate the same or corresponding parts.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical indication location G01J 5/02 G01J 5/02 J

Claims (1)

(57) [Claims] 1. A black body portion of a thermal infrared detecting device attached to a header catches infrared light transmitted through an infrared transmitting filter from an opening at an upper portion of a cap and detects infrared light emitted from an object. In the infrared detecting element, the infrared transmitting filter is formed of a cylindrical or prismatic infrared transmitting crystal, a top surface of the column or the prism is disposed in an opening at an upper portion of the cap, and a bottom surface extends near an upper portion of the black body portion. An infrared detecting element having a structure for projecting light and having the side surface of the cylindrical or prismatic shape covered with a film that reflects infrared light.