JP2541863B2 - Pyroelectric infrared detector - Google Patents

Description

The present invention relates to the structure of a pyroelectric infrared detector.

[Conventional technology]

The pyroelectric infrared detector uses, as a signal, a change in spontaneous polarization caused by a change in temperature of the pyroelectric material caused by absorption of infrared light radiated from an object to be detected.

In the pyroelectric infrared detector, the pyroelectric element is thinned to about 50 to 100 μm to reduce the heat capacity and to quickly respond to a change in infrared thermal energy to improve the detection sensitivity.

5 to 8 show a support structure of a pyroelectric infrared detection element (hereinafter referred to as a detection element) used to prevent an increase in heat capacity. In each figure, 1 is a detecting element, 1a is a light receiving electrode, 1b
Denotes a ground electrode, and 2 denotes an external lead terminal attached to the case 3. The detection element 1 is housed in a case 3 having a light receiving window 4 together with a substrate on which electronic components constituting a circuit are mounted, but the substrate on which the electronic components are mounted is not shown in the drawings. FIG. 5 shows the electrodes 1a and 1b of the detection element 1.
An example in which the detecting element 1 is supported in the air by connecting the lead wire 5 to the external lead terminal 2 and the detecting element 1 is suspended in the air. In FIG. 6, the detecting element 1 is mounted on a mount base 6 installed in the case 3 via an insulating substrate 7. 7 shows an insulating substrate 7 supported by the external lead terminals 2.
An example in which a heat insulating pattern 8 is partially protruded above and the detecting element 1 is supported on the heat insulating pattern 8, FIG. 8 shows the detecting element 1 on a perforated insulating substrate 9 attached to the external lead terminals 2. It is an example of installing.

[Problems to be Solved by the Invention]

However, the support structure of FIG. 5 is effective in preventing an increase in heat capacity, but lacks stability in supporting the detection element 1, and the detection element 1 is extremely thin, which makes it difficult to handle and assemble. There is a problem. Although the support structure of FIG. 6 is excellent in the stability of support of the detection element 1,
There is a drawback that the insulating function of the insulating substrate 7 is not sufficient, and conversely, the heat capacity is increased and sensitivity and responsiveness are reduced. Further, in the support structure of FIG. 7, it is difficult to make the heights of the heat insulating patterns 8 that partially project on the insulating substrate 7 uniform, and the detection element 1 is mounted at an angle, or each detection is performed. If the gap between the insulating substrate 7 and the detection element 1 is different for each device, the heat insulating action is different for each device, and the sensitivity and responsiveness of each detector vary.

Although the support structure of FIG. 8 eliminates this drawback,
Since the installation of the detection element 1 requires a certain area, there is a limit to the reduction of heat capacity. Further, in the support structure of FIG. 6, the back surface side of the insulating substrate 7 constitutes a circuit such as a resistor and a FET. Although it can be used for the mounting surface of electronic parts, the supporting structure of FIG. 8 reduces the plane area of the insulating substrate and cannot secure a mounting space.

The root causes of the above-mentioned problems are also significant in the manufacturing method of the detection element. The detection element is usually made by the slice method. In this method, the ferroelectric ceramic composition particles are pressed into a columnar shape and fired at 1200 ° C. The obtained fired body is sliced into about 0.2 mm, and then 0.1 mm is subjected to polishing finish to be a sensing element material. Is the way. According to this method, since the finished element material is sintered by firing, it is almost impossible to make a hole in the material again. Therefore, as long as the element material manufactured by the slicing method is used, it is unavoidable to use the support structure shown in FIGS.

An object of the present invention is to solve the above problems, to easily construct a sensor circuit, to stably support a detection element in a fixed position, to have a large strength against external vibration and impact, and to have a large thermal insulation effect on the detection element. It is to provide an infrared detector.

[Means for solving the problem]

To achieve the above object, in a pyroelectric infrared detector according to the present invention, a pyroelectric infrared detector having a circuit board, an infrared detection element, and a plurality of external lead terminals, wherein the circuit board is , The electronic components that make up the circuit are mounted, the infrared detection element has electrodes on both sides of the plate, the external lead terminals are inserted through the circuit board, and the infrared detection element is located at each upper end. Is supported in a horizontal posture, and the upper end portion thereof has a support portion for supporting the plate surface of the detection element, and the infrared detection element is supported on the support portion of the external lead terminal and is supported by at least one external lead terminal. The electrode is electrically connected to the wiring pattern of the circuit board or the ground.

[Action]

In the present invention, unlike the conventional slicing method, the ferroelectric element composition is preliminarily formed into a sheet shape having a thickness of about 0.2 mm, and then punched by a press to open the attachment hole of the external lead terminal and a predetermined size. After cutting into a shape, it is fired at about 1200 ° C. to sinter this, and after firing, an element material is used by polishing to a thickness of 0.1 mm. FIG. 2 shows the obtained infrared detection element. The detection element 11 is plate-shaped and has mounting holes 12a and 12b for external lead terminals at diagonally opposite corners, a pattern of a light receiving electrode 11a is formed on one surface, and a pattern of a ground electrode 11b is formed on the other surface to form a pair. It is extended to the periphery of the mounting holes 12a and 12b.

In the present invention, the external lead terminal has a support portion that supports the detection element, and the mounting hole 12a or 12b of the detection element 11 and the plate surface of the detection element 11 are supported on the support portion of each external lead terminal at a fixed position. The detection element is supported. In the pyroelectric infrared detector according to the present invention, since the detecting element is directly held by the external lead terminal, the supporting stability and the supporting strength of the detecting element are high. By forming a gap between them, heat insulation can be easily ensured, and at the same time, the electrical connection between the circuit board and the detection element can be performed using the external lead terminal.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows an infrared detecting element manufactured by the sheet method. In the case of the embodiment, the detection element 11 is a rectangular plate-shaped body, and mounting holes 12a and 12b are opened at diagonal corners. A pattern of the light receiving electrode 11a is provided on one surface of the detection element 11 and a ground electrode 11b is provided on the other surface thereof, and each pattern is extended to one corner so as to surround the corresponding mounting holes 12a, 12b.

In FIG. 1, a pyroelectric infrared detector is a circuit board on which an infrared detecting element 11 and electronic parts constituting a circuit are mounted.
13 and 13 are incorporated in a case 14. Case 14
Is a bottom plate 15 covered with a cover 16, and a light receiving window 16a is formed in a part of the upper surface of the cover 16. Circuit board 13
Is a plate-like body using alumina porcelain, and a resistor 17, a semiconductor element 18, etc. are mounted on the wiring pattern formed on the substrate 13.

3A to 3C show the shape of the external lead terminal used in the present invention. FIG. 3 (a) is an example of the lead terminal 19b for electrically connecting the pattern of one of the electrodes of the detection element (the ground electrode 11b in the embodiment) to the outside. This lead terminal 19b
Is to be inserted into the mounting hole 12b of the detection element 11, and
The shaft end portion that is inserted into 2b is reduced in diameter over a certain range from the upper end, and a step as a support portion 21 of the detection element 11 is formed at a certain position of the shaft.

FIG. 3B is a corner portion of the plate surface of the detection element 11 shown in FIG.
It is an example of external lead terminals 19c and 19d for supporting the portions 12c and 12d. In the case of the embodiment, the external lead terminals 19c and 19d serve as input / output terminals of the infrared detector, but
It does not electrically connect to 11, but only serves as a support terminal. Therefore, a seat portion that supports the bottom surface of the detection element 11 as a support portion 21 is formed at the upper ends of the external lead terminals 19c and 19d so as to project to the outer diameter of the shaft. FIG. 3C shows a lead terminal 19 a that electrically connects the detection element 11 and the circuit board 13. Although this lead terminal 19a is not an external terminal, in order to insert the lead terminal 19a into the circuit board 13 and regulate the protruding length upward, if a certain range of the lower end portion of the shaft of the lead terminal 19a is reduced and a step is provided. It is convenient.

FIG. 4 shows the support structure of the detection element by the external lead terminals 19b, 19c, 19d. The lead terminal 19a is not shown.

In FIG. 1 and FIG. 4, three external lead terminals 19b,
19c and 19d project downward from the case 14 and are supported by the bottom plate 15, and the circuit board 13 is inserted and held by the external lead terminals 19b, 19c and 19d projecting on the bottom plate 15 and fixed by a conductive resin. There is. The detection element 11 is installed above the substrate 13 with the light receiving electrode 11a facing the light receiving window 16a of the case 14. The opening positions of the mounting holes 12a and 12b provided in the detecting element 11 correspond to the supporting positions of the substrate by the external lead terminals, and the detecting element 11 is placed in the mounting hole 12b as shown in FIG. The external lead terminals 19b protruding on the substrate 13 are inserted and supported horizontally at the same height position on the stepped portions and the seats at the upper ends of the other external lead terminals 19c and 19d.
The external lead terminals 19b, 19c, 19d and the detection element 11 are fixed at fixed positions above the substrate 13 by the conductive resin adhesive 20 applied between them. Distance H between substrate 13 and detection element 11
Is determined by preset height positions of the step and the seat of the external lead terminal. Usually, this interval H is appropriately set to a height of 50 μm or more.

Circuit pattern of the circuit board 13 and light receiving electrode of the detection element 11
The terminal pattern of 11a is electrically connected by the lead terminal 19a. When the lead terminal 19a shown in FIG. 3 (c) is used, it is inserted into the hole of the circuit board 13 and the upper portion thereof is inserted into the mounting hole 12a of the detection element 11, and the conductive resin adhesive 20 is applied to each of them. To fix it.

The mounting hole is not limited to a perfect circle, but may be a part of the mounting hole opened at the edge or a shape capable of locking the lead terminal, for example, a part of the corner cut out.

In the above embodiment, the detection element 11 is stably fixed and supported together with the circuit board 13 on the respective support portions 21 of the three external lead terminals 19b, 19c, 19d, and the mounting position of the detection element 11 is on the circuit board 13. It is defined by the height of the protruding external lead terminal support.

The number of external lead terminals supporting the detection element 11 is not limited. In the embodiment, the light receiving electrode of the detection element 11
The lead terminal 19a for connecting between the circuit patterns of the circuit board 13a and 11a is also not drawn out of the case 14, but the bottom plate 15 of the case 14 has four holes for drawing out external lead terminals. Ordinary external lead terminals can be inserted and fixed in the holes when they are present. It is desirable to insert it into the hole and cover the downward protruding end with an insulating resin at that time, and to cover it with a conductive resin as a measure against noise.

In the above embodiment, the shape of the external lead terminal is properly used, but the shape of the external lead terminal 1b shown in FIG. 3 (a) can be commonly used by providing the mounting holes at the corners 12c and 12d of the detection element. .

〔The invention's effect〕

As described above, according to the present invention, since the detection element is supported on the support portion provided on the external lead terminal provided in the infrared detector, and is fixed in a fixed position of the external lead terminal by being fixed with the conductive resin. The detection element can be supported stably, and the conductive resin acts as a cushioning material against external vibrations and shocks so that it does not affect the detection element. Also, the distance between the detection element and the circuit board is set in advance and The space required for heat insulation can be secured. ADVANTAGE OF THE INVENTION According to this invention, construction of a sensor circuit is easy and there exists an effect which can mass-produce the product with uniform quality and performance.

[Brief description of drawings]

FIG. 1 is a sectional view of a pyroelectric infrared detector showing an embodiment of the present invention, FIG. 2 is a plan view of a detecting element, and FIG.
(C) is a view showing the shape of the external lead terminal and the lead terminal, FIG. 4 is a view showing a mounting procedure of the detection element, and FIGS. 5 to 8 are sectional views showing a conventional example of a pyroelectric infrared detector. Is. 11 …… Detection element, 12a-12d …… Mounting hole 13 …… Circuit board, 14 …… Case 19b-19d …… External lead terminal 20 …… Conductive resin adhesive, 21 …… Support

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Tomohiro Yamamura 3158 Shimookubo, Osawano-cho, Kamishinkawa-gun, Toyama Prefecture Inside Hokuriku Electric Industry Co., Ltd. (72) Inventor Mitsuo Keda 1-14-1 Shinzayama, Sayama City, Saitama Prefecture No. 1 Oizumi Manufacturing Co., Ltd. (72) Inventor Yoichi Tanaka 1-11-4 Shin-Sayama, Sayama-shi, Saitama

Claims (1)

(57) [Claims] 1. A pyroelectric infrared detector having a rotating substrate, an infrared detecting element, and a plurality of external lead terminals, wherein the circuit board is mounted with electronic components constituting a circuit. The infrared detection element has electrodes on both sides of the plate, and the external lead terminals are for inserting the circuit board and supporting the infrared detection element in a horizontal posture at each upper end, and the upper end is for detecting the infrared detection element. The infrared detecting element has a supporting portion that supports the plate surface of the element, and the infrared detecting element is supported on the supporting portion of the external lead terminal, and the electrode is electrically connected to the wiring pattern of the circuit board or the ground by at least one external lead terminal. A pyroelectric infrared detector characterized in that