JPH0750679Y2 - Thermopile type infrared sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a structure of a thermopile type infrared sensor.

[Conventional technology]

Typical structure of conventional thermopile type infrared sensor,
This will be described with reference to FIGS. 2 (a) and 2 (b). Fig. 2 (a)
Is a sectional view of this product, and FIG. 2 (b) is a plan view. The insulating film 2 coated on one surface of the substrate 1 constitutes the heat sink 3 in the peripheral portion of the substrate 1 and the diaphragm 5 in the pit 4 portion punched in the central portion of the substrate 1. A black body 6 serving as an infrared absorber is attached to the central portion of the diaphragm 5, and around the black body 6,
The heat sink 3 has a hot junction 71 on the diaphragm 5.
A thermopile 70 consisting of a number of thermocouples 7 connected in series with one another having cold junctions 72 is arranged on top of them. The infrared rays absorbed by the black body 6 heat the hot junction 71 and generate a thermoelectromotive force due to the temperature difference from the cold junction.

[Problems to be Solved by the Invention] In this structure, in the hot junction portion 71 and the cold junction portion of the thermocouple 7,
In order to make the temperature difference with 72 easier, the diaphragm 6 is
The thermal conductivity should be as low as possible. However, if a diaphragm with a low thermal conductivity is used, the amount of heat that the black body 6 absorbs and stores the infrared rays emitted from the temperature measurement object is
There is a drawback that it becomes difficult to reach 71 and sensitivity decreases.

Therefore, an object of the present invention is to provide a highly sensitive thermopile type infrared sensor.

[Means for Solving the Problems]

Therefore, in the present invention, the infrared absorbing black body and the hot junction of the thermocouple are thermally coupled by a hard carbon film which is an insulator having a large thermal conductivity.

〔Example〕

 An embodiment of this invention will be described below.

FIG. 1 is a sectional view showing an embodiment of the present invention. Board 1
A silicon wafer was used as a substrate, and one surface thereof was thermally oxidized to form an insulating film 2 made of silicon dioxide. Next, the central portion of the substrate 1 was perforated by etching to form a pit 4, and the insulating film 2 remaining in the pit portion was used as the diaphragm 5. A hard carbon film 8 was coated on the center of the diaphragm 5, and gold black was deposited on the center of the diaphragm 5 as a black body 6 for absorbing infrared rays. Around the black body 6, a thermopile composed of a large number of thermocouples 7 connected in series was arranged. In this case, the hot junction 71 of the thermocouple 7 was provided on the hard carbon film 8, and the cold junction 72 was provided on the heat sink 3 formed in the peripheral portion of the substrate 1.

The hard carbon film adopted in this proposal is an amorphous carbon film that combines hydrogen and is formed by plasma polymerization in a hydrocarbon gas atmosphere. It is a film showing a high thermal conductivity of about 5 times.

Therefore, the amount of heat of the black body 6 that has absorbed infrared rays and heated up is quickly transmitted to the hot junction 71 of the thermocouple 7 via the hard carbon film 8 and, at the same time, the temperature difference between the many hot junctions 71 is increased. Is eliminated by the soaking effect of the hard carbon film 8.

On the other hand, since the heat sink 3 in which the cold contacts 72 of the thermocouple 7 are installed is isolated from the hard carbon film 8, the heat conduction from the black body 6 is extremely small, and both contacts 7 of the thermocouple 7 are
A large temperature gradient is generated between 1 and 72, and a large thermoelectromotive force is generated.

[Effect of device]

As explained above, in the thermopile type infrared sensor of the present invention, the responsiveness and the sensitivity are simultaneously improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of a thermopile type infrared sensor of the present invention, and FIG. 2 is a sectional view and a plan view showing the structure of a conventional thermopile type infrared sensor. 1 ... Substrate, 2 ... Insulating film, 3 ... Heat sink, 4 ...
… Pit, 5 …… Diaphragm, 6 …… Black body, 7 …… Thermocouple, 71 …… Hot junction, 72 …… Cold junction, 8 …… Hard carbon film.

Claims (1)

[Scope of utility model registration request] 1. An insulating film coated on one surface of a substrate constitutes a heat sink in the peripheral portion of the substrate, and a diaphragm in a pit portion punched in the central portion of the substrate,
A hard carbon film is laminated in the center of the diaphragm,
A black body as an infrared absorber is applied to the center of the hard carbon film, and the hard carbon film has a hot junction on the hard carbon film and a cold junction on the heat sink connected in series around each other. A thermopile type infrared sensor characterized in that a thermopile composed of a large number of thermocouples is arranged.