JPH0543037U - Infrared detection thermopile - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a highly sensitive thermopile for infrared detection. [Configuration] Infrared absorber on the front and back surfaces of the insulating substrate 18
20a, 20b and series thermocouple patterns 4a, 4b are formed. The series thermocouple patterns 4a and 4b are connected in series via connecting means to increase the number of thermocouples 4 connected.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a thermopile for infrared detection using a thermocouple.

[0002]

[Prior Art]

 Thermopile is used as an infrared detection device for opening and closing automatic doors.

FIG. 6 shows a cross-sectional structure of a conventional thermopile, and FIG. 7 shows a pattern diagram of a thermocouple 4 used in this type of thermopile.

In these drawings, the thermopile 1 is housed in a package 14, and a base 3 is provided on the lower end side of the package 14. A silicon substrate 16 is provided on the base 3, and an insulating substrate 18 of a silicon nitride thin film is formed on the upper surface of the silicon substrate 16 by vapor deposition or the like. An infrared absorber 20 made of metal such as gold black is provided at the center of the silicon nitride thin film on the insulating substrate 18. A plurality of thermocouples 4 are radially arranged around the infrared absorber 20 as shown in FIG.

The thermocouple 4 includes a first thermoelectric pattern 10 made of bismuth (Bi) and a second thermoelectric pattern 12 made of antimony (Sb), and the first thermoelectric pattern 10 and the second thermoelectric pattern 10 are formed. The thermoelectric patterns 12 are arranged radially as shown in the figure, and the first thermoelectric pattern 10 is joined to the second thermoelectric pattern 12 on the side close to the infrared absorber 20. The portion forms a warm joint portion 13, and similarly, the joint portion on the far side from the infrared absorber 20 forms a cold joint portion 15. The plurality of thermocouples 4 are connected in series. The thermocouple 4 connected in series is connected to the signal extraction electrode 28 via the aluminum wiring 26, further connected to the lead wire terminal 32 via the bonding wire 30, and is drawn out to the outside of the package 14. In addition, a window 24 is provided in the center of the ceiling of the package 14 to allow infrared rays to enter from the outside.

FIG. 5 shows the arrangement of the infrared absorber 20 of the conventional thermopile 1 and the hot junction 13 of the thermocouple 4, and the infrared absorber 20 is placed near the hot junction 13 of the thermocouple 4. It is arranged via a space 6.

In the thermopile having the above structure, when infrared rays of, for example, a human body enter through the window 24 of the package 14, the infrared absorber 20 receives the infrared rays and converts the infrared rays into heat energy (temperature, heat quantity), It is transmitted to the hot junction 13 via the space 6. This causes a temperature difference ΔT between the hot junction portion 13 and the cold junction portion 15 of the thermocouple 4, which causes a potential difference ΔV in the thermocouple 4. The potential difference corresponding to the number of thermocouples 4 connected in series is sent to the signal extraction electrode 28 connected via the aluminum wiring 26 as shown in FIG. Detection is done.

[0008]

[Problems to be solved by the device]

 However, in the conventional thermopile 1, as shown in FIG. 5, the thermocouples 4 are formed only on the surface of the insulating base plate 18, and the number of the thermocouples 4 arranged is one side of the insulating base plate 18 ( Since the number of thermocouples 4 is limited to the number that can be accommodated on the surface, the number of thermocouples 4 is insufficient, and the detection output of infrared rays becomes insufficient, resulting in a drawback that sensitivity is deteriorated.

Further, since the sensitivity of the thermopile 1 increases in proportion to the number of the thermocouples 4, in order to increase the sensitivity, for example, the line width of the thermoelectric patterns 10 and 12 of the thermocouple 4 may be reduced to reduce the thermoelectricity. It is conceivable to increase the number of pairs 4, but in this case, if the line width is narrowed, the resistance of the thermoelectric patterns 10 and 12 becomes large, and the sensitivity is rather deteriorated. It is also possible to increase the area of the infrared absorber 20 to expand the outer circumference and increase the number of thermocouples 4, but this causes a problem that the device becomes large.

The present invention is to solve the above-mentioned conventional problems, and an object thereof is to provide a thermopile for infrared detection with high sensitivity while avoiding an increase in the size of the device.

[0011]

[Means for Solving the Problems]

 The present invention is configured as follows to achieve the above object. That is, the present invention is provided with an infrared absorber on the surface of an insulating substrate, and a plurality of thermocouple patterns are formed, with the side close to the infrared absorber being a hot joint and the far side being a cold joint, and each thermocouple pattern is formed. In the infrared detection thermopile in which are connected in series, a plurality of thermocouple patterns connected in series are formed on the back surface of the insulating substrate in the same manner as on the front surface side.The series thermocouple pattern on the front surface side and the back surface side The series thermocouple pattern is characterized in that it is connected in series via a connecting means.

[0012]

[Action]

 Providing multiple thermocouple patterns connected in series on the front and back surfaces of the insulating substrate. These thermocouple patterns are connected in series via connecting means. As a result, the number of thermocouple patterns is increased and the heat is extracted sufficiently, so that the sensitivity of the thermopile can be increased.

[0013]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. In the description of the present embodiment, the same parts as those in the conventional example are designated by the same reference numerals, and detailed description thereof will be omitted. A feature of this embodiment is that a plurality of thermocouple patterns 4 connected in series with the infrared absorber 20 are provided on the front surface and the back surface of the insulating substrate 18, and the thermocouple patterns 4 are connected in series via a connecting means. Other than that, the configuration is the same as that of the conventional example. FIG. 1 shows the cross-sectional structure of the essential part of the infrared detecting thermopile. 2 is shown from above in FIG. 1, and FIG. 3 is shown from below in FIG. In these drawings, the infrared absorber 20 and the thermocouple pattern 4a are formed on the surface of the insulating substrate 18. The thermocouple pattern 4a is formed by connecting a plurality of thermocouples 4 each including a first thermoelectric pattern 10 and a second thermoelectric pattern 12 in series. An infrared absorber 20b and a thermocouple pattern 4b are also formed on the back surface of the insulating substrate 18, the infrared absorbers 20 on the front and back sides are placed at positions overlapping each other, and the thermocouple pattern 4b is the same as 4a. 4 are connected in series. One end A of the thermocouple pattern 4a on the front side is connected to one end B of the thermocouple pattern 4b on the back side through the first through hole 7a provided in the insulating substrate 18, and the other end C of the thermocouple pattern 4b on the back side is connected. , Is connected to the other end D of the thermocouple pattern 4a on the front surface through the second through hole 7b, and thus, all the thermocouples 4 on the front and back surfaces are connected in series. Then, the detection signal is extracted from the signal extraction electrode 28 on the surface to the outside of the package 14.

In this embodiment, the infrared absorbers 20a, 20b and the thermocouple patterns 4a, 4b are provided on the front and back surfaces of the insulating substrate 18, and the thermocouple patterns 4a, 4b are connected in series via a connecting means. Therefore, the number of thermocouples 4 can be significantly increased (doubled) as compared with the conventional one without changing the size of the infrared absorber 20 or the line width of the thermoelectric patterns 10 and 12 of the thermocouple 4. As a result, the hot junction 13 of the thermocouple 4 is doubled, and the heat transfer from the infrared absorber 20 to the hot junction 13 of the thermocouple 4 is performed efficiently and promptly, and the cold junction with the hot junction 13 is performed. The temperature difference ΔT with the portion 15 can be increased. Therefore, as described above, the sensitivity of the thermopile 1 is improved in proportion to the number of the thermocouples 4, so that the above-described configuration makes it possible to obtain a thermopile with high sensitivity.

The present invention is not limited to the above-mentioned embodiment, and various embodiments can be adopted. For example, in the above-described embodiment, the infrared absorber 20 and the hot junction 13 of the thermocouple 4 are in contact with each other via the gap 6, but as shown in FIG. , 2b may be provided so that the infrared absorber 20 and the hot junction 13 of the thermocouple 4 face each other through the insulating layer 5.

Further, in the above embodiment, the infrared absorbers 20a and 20b are provided on both front and back surfaces of the insulating substrate 18, but one of them (20a or 20b) may be omitted.

[0017]

[Effect of the device]

 In the present invention, since the series thermocouple patterns provided on the front surface and the back surface of the insulating substrate are connected in series through the connecting means, the size of the infrared absorber and the line width of the thermocouple pattern of the thermocouple are changed. The number of thermocouples can be significantly increased as compared with the conventional one. As described above, the sensitivity of the thermopile is improved in proportion to the number of thermocouples, so that the above-mentioned configuration makes it possible to obtain a thermopile with high sensitivity.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main configuration of an infrared detection thermopile according to this embodiment.

FIG. 2 is a plan view of FIG. 1 viewed from above.

FIG. 3 is a bottom view of FIG. 1 seen from below.

FIG. 4 is a cross-sectional view of another structure of the heat transfer portion of the infrared detection thermopile according to the present embodiment.

FIG. 5 is a cross-sectional view of a thermocouple portion of a conventional infrared detecting thermopile.

FIG. 6 is a cross-sectional view of a conventional infrared detecting thermopile.

FIG. 7 is a plan view of a thermoelectric pattern of a conventional infrared detecting thermopile.

[Explanation of symbols]

 4 Thermocouple 7 Through hole 13 Hot junction 15 Cold junction 18 Insulating substrate 20 Infrared absorber

Claims (1)

[Scope of utility model registration request] 1. An infrared absorber is provided on the surface of an insulating substrate,
A plurality of thermocouple patterns are formed with the side closer to the infrared absorber as a warm junction and the far side as a cold junction, and each thermocouple pattern is connected in series in an infrared detecting thermopile, wherein the insulating substrate A plurality of thermocouple patterns connected in series are formed on the back surface as well as the front surface side, and the series thermocouple pattern on the front surface side and the series thermocouple pattern on the back surface side are connected in series via connecting means. A characteristic thermopile for infrared detection.