JPH01199481A - Thermopile - Google Patents

Abstract

PURPOSE:To obtain a highly sensitive thermopile provided with a warm contact disposed at a small detecting area without decreasing an S/N ratio by a method wherein two or more of a single thermopile, which is provided with a cold contact and a warm contact disposed at a cylindrical heat sink and its center respectively and has a length nearly equal to the diameter of the cylinder, are connected in a pair and series. CONSTITUTION:A thermopile provided with a warm contact and a cold contact disposed on a cylindrical heat sink 1 of an electrical insulating material and a center of the cylinder respectively is structured in such a manner that two or more unit thermocouples a and b in a pair which have a length nearly equal to the diameter of the cylinder are connected in series so as to increase in an output. For instance, a first substance a and a second substance b are alternately arranged on an electrical insulating substrate 1, whose centers and peripheries are connected in series respectively. And, a first layer pattern is formed as mentioned above, an insulating thin film c is overcoated on its upper face, a second layer pattern is formed thereon and connected with the first layer pattern in series, and furthermore two or more layer patterns are formed the same above. In this process, a soluble film d may be attached to an opening of the substrate 1, which is removed by a solvent after the formation of a multilayer film.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a thermopile in which a large number of hot junctions are arranged in multiple layers in a small radiant energy incident area.

In order to detect abnormal heat generation in electrical circuit parts, etc., it is convenient to measure the surface temperature without contact using a radiation temperature needle, but in recent years, the miniaturization of components has been remarkable, and the detection accuracy in L measurement has improved. was desired.

For this purpose, it is necessary to make the detection area of the thermopile used in the radiation thermometer J-sized and highly sensitive.

A conventional thermopile was constructed as shown in FIG.

That is, a plurality of pairs of thermocouples, the first material a and the second material, were arranged alternately on the surface of the electrically insulating substrate 1, with the central portion serving as a group of hot contacts and the outer periphery serving as a group of cold contacts.

In such a configuration, if the line widths of the first substance a and the second substance A are constant, the detection area occupied by the hot junction group cannot be made smaller than the circumference of the line width times the number of thermocouple elements. .

In addition, if the line width is kept constant, and the detection area is made smaller while keeping the number of thermocouple elements constant, the overall electrical resistance will increase in inverse proportion to the line width, leading to an increase in thermal disturbance H and poor S/N ratio. Since it is a ratio, it has the disadvantage that it cannot be used for the above-mentioned purpose of handling minute signal output.

As a result of studies to eliminate such drawbacks, the present invention has found that the S/N
We have now provided a highly sensitive thermopile in which a hot junction is arranged in a small detection area without reducing the ratio, and a method for manufacturing the same with high reliability.

Embodiments of the present invention will be described below based on the drawings.

FIG. 2 shows an example of an embodiment of the present invention.

FIG. 2 shows the wiring pattern of the -th layer. Similar to FIG. 1, a first material a and a second material A are alternately arranged on the surface of an electrically insulating substrate (for example, an alumina substrate) 1, and each The central part and the outer periphery are connected in series.

Here, in order to reduce the detection area of the hot junction, the number of elements is reduced and extended close to the center.

If this continues, the sensitivity will decrease due to a decrease in the number of elements.

Therefore, after forming the -th layer pattern, the upper surface C,
As shown in FIG. 3, the insulating thin film C of the -th calendar is overfooted.

Subsequently, a second layer pattern can be formed on this first layer insulating thin film E.

Here, the first layer pattern and the second layer pattern can be connected in series to double the number of elements.

Similarly, by forming a plurality of layers and increasing the number of elements, it is possible to obtain sensitivity equal to or greater than that of the conventional technique.

However, as the number of layers increases, the amount of infrared light transmitted to the lower layer decreases, so there is a limit.

In this embodiment, the thermoelectric material must have a large difference in Seebeck coefficient between the first substance a and the second substance A, high thermal conductivity, and low electrical conductivity.

BilSb is used in consideration of these three conditions.

In these methods, a plurality of thermocouple patterns are formed on an alumina substrate that also serves as a heat sink using a vacuum evaporation method.

At this time, it is also possible to stick the soluble film d shown in FIG. 3 to the opening of the alumina substrate and remove it with a solvent after forming the multilayer thin film.

Hot junctions need to have as little heat loss as possible.

Next, as the insulating thin film of each layer, in order to reduce the heat loss, a polymer film with low thermal conductivity or generally S+O** can be used.

Furthermore, in order to effectively convert infrared energy into heat and heat only the hot junction, an infrared absorbing film e (goldfish, InSb, etc.) is formed above the hot junction.

The thermopile manufactured in this way has a hot junction in a minute area in the center of the cylinder, and it is possible to install a larger number of elements than before, and it is also highly sensitive to infrared energy information from a minute light source. It has a high sensitivity and S/N ratio, which reduces the causes of defects such as disconnections and short circuits, making it possible to dramatically improve reliability.

Next, in order to make the object of the present invention more effective, high sensitivity can be achieved by doing the following in addition to the above embodiments.

In the above examples, it was observed that when infrared rays are irradiated not only to the hot junction area but also to other parts, a part of the infrared rays is converted into heat, and this heat warms the cold junction area. This reduces the difference in thermoelectromotive force between the hot junction and the cold junction, causing a decrease in sensitivity.

Therefore, as shown in FIG. 5, an infrared reflective film r is coated on the area other than the hot junction area to prevent infrared rays from being converted into heat.

In Figure 6, incoming infrared rays are focused on the hot junction area by lens 2 (Fresnel lens, etc.), preventing the temperature rise of the cold junction area and increasing the amount of energy incident on the hot junction area, resulting in higher sensitivity. has been realized.

[Brief explanation of the drawing]

Fig. 1 shows a pattern diagram of a conventionally used thermopile, and Fig. 2 shows a pattern diagram of a conventionally used thermopile.
A pattern diagram of layers is shown. FIG. 3 shows a second layer pattern that can be formed on the first layer pattern of the thermopile shown in FIG. Similar patterns can be formed in the third and subsequent layers. Further, FIG. 4 shows a cross-sectional view of the thermopile in the present invention. FIGS. 5 and 6 each show a method of irradiating infrared rays only to a minute area of hot junctions concentrated at the center of the cylinder. 1-1 Stunned magnetic substrate, a~first substance. b - second substance; C - insulating thin film; d-Soluble film, C-Infrared absorbing film. r-Infrared reflective film, 2-lens straw Figure 1 Summer 22 Figure 3 Figure 4 Man 4 Figure 5 Figure 1989 3
May 14, 1, Display of the case Patent Application No. 185966 of 1985 3, Relationship with the case of the person making the amendment Patent applicant 5, Column 6 for a brief explanation of the drawings of the specification subject to the amendment, Contents of the amendment No. Delete page 7, line 5 to line 8 of the same page. Page 7, line 9, "Figure 4" is corrected to "Figure 3." Page 7, line 11, "Fig. 5, Fig. 6" is corrected to "Fig. 4, Fig. 5."

Claims (4)

[Claims] (1) In a thermopile that has a cold junction on a cylindrical heat sink made of an electrically insulating material and a hot junction at the center of the cylinder, multiple pairs of single thermocouples with a length approximately equal to the diameter of the cylinder are used. , thermopiles characterized in that they are connected in series to increase the output. (2) A multilayer thermopile characterized in that after the thermopile is formed, a thermopile is further formed on top of the thermopile via an electrically insulating thin film, and the thermopile is connected in series with the thermopile to increase the output. (3) The thermopile according to item 2 above, characterized in that the infrared incident area other than the small area of the hot junction concentrated at the center of the cylinder is coated with an infrared reflective thin film. (4) The thermopile according to item 2 above, characterized in that a lens is provided so that infrared rays incident on only a minute region of the hot junction concentrated at the center of the cylinder can be focused.