JPH03245022A - Pyroelectric infrared-ray detector - Google Patents

Abstract

PURPOSE:To simplify a structure by using a composite FET group wherein FETs having a plurality of circuits are housed in one package, and constituting detecting circuits of three or four circuits. CONSTITUTION:An electrode pattern for taking out a generated potential is formed on the rear surface of a pyroelectric body 12 by vapor deposition, and four pyroelectric elements 13 are constituted. A conductor pattern is formed on a wiring supporting board 14 so that four circuits are constituted. The parts of bias resistors and FETs are attached to the rear surface of the board 14. When four circuits are constituted, the space can be reduced by using a FET 15 containing two circuits. A supporting stage 23 is used for connecting between the pyroelectric body 12 and the board 14. A conductive bonding agent is applied to the cross section of the stage 23. At this time, lead-out parts for connections are provided on the surface of the pyroelectric body 12 with a vapor deposition pattern. The conductive bonding agent is applied from this surface to the supporting stage 23. These constituent parts are electromagnetically shielded in an airtight mode with a case 25 to which an optical filter 24 is attached and a stem 27 having six leads 26.

Description

[Detailed description of the invention] [Industrial application fields] The present invention relates to the structure of a pyroelectric infrared detector.

7. Prior Art] A pyroelectric infrared detector is an element that receives infrared rays emitted from an object and converts it into an electrical signal, and is widely used as a human body detection sensor. Conventionally, a dual element as shown in FIG. 2 or a dual twin element using two circuits of dual elements has been used as a human body detection sensor. The electrical circuit diagram of the dual element is shown in FIG.

Elements (1-a) and (1-b) are connected in series or in parallel with opposite polarities in order to cancel the output of each element caused by room temperature fluctuations, etc. The output from the element is connected to the impedance conversion FET (4) via the bias resistor (3), and the drain terminal (5),
It is connected to the outside through a source terminal (6) and a ground terminal (7). In the case of a dual twin element, two circuits similar to those shown in FIG. 3 are constructed within the same housing.

In order to further improve the reliability of currently used infrared detectors, an infrared detector having three or more detection circuits in the same housing was proposed as shown in Utility Application No. 80746/1983. has been done. The element arrangement is shown in FIG.

Here element (8al b) C9a, b) (10
-a, b) (11-a, b) both 3rd
The circuits shown in the figure constitute four circuits.

In the case of FIG. 4, a temperature-compensated single element is shown, but the same applies to dual elements as shown in FIGS. 1 and 2. Naturally, in such an infrared detector, the number of beams in the detection area increases according to the number of elements, and the number of signals extracted increases accordingly. Therefore, it has the advantage of being able to more clearly distinguish minute movements of the detected object and between the detected object and other movement factors than conventional detectors.

=Problem to be solved by the invention] A pyroelectric infrared detector having four detection circuits (in some cases, three circuits) as shown in L has characteristics J:, various ζ and gains compared to conventional elements. However, the reason why it has not yet been put into practical use is that its structure is complicated and it is difficult to fit it into a TO5 package or similar packages.

Therefore, a large package can be used, but in this case, there is a drawback that a blind spot occurs depending on the size of the package, especially in a method that uses a mirror to condense infrared energy.

Furthermore, if an attempt is made to fit the parts into the TO-5 package, the spacing between parts and wiring lines become narrower, increasing the possibility of short circuits, resulting in a significant drop in assembly yield.

What is desired is a structure that allows easy construction of the four (or three) detection circuits shown in Figure 4 using a To 5 package with fewer blind spots and an equivalent package. .

Means for Solving Two Problems] The present invention can solve the above problems by using a composite FET in which two circuit FETs are housed in a single bar/cage as shown in FIG. Composite “4F”
ET can be manufactured in the same size as a conventional single-circuit FET, and conventionally it was difficult to use two circuits, but by using the above-mentioned composite FET, three or four circuits can be used. has become easier to configure.

This dual function prevents the package from becoming large and maintains the blind spot caused by the package in the same state as before.
It has become possible to more clearly distinguish between the detected object and other operating factors.

[Example] FIG. 1 shows an example of the present invention. (12) shows a pyroelectric material, in which a PZT ceramic was used on a thin plate. (1
2) A t-pole pattern is formed by vapor deposition on the front and back sides of the pyroelectric body to extract the generated potential, and four pyroelectrics are formed on the front and back sides of the pyroelectric body. element(
13) was constructed.

(14) indicates a wiring support board, on which a conductor pattern is formed to form one circuit file of the circuit shown in FIG.

The wiring support substrate is generally an alumina substrate, but a printed circuit board or other materials may also be used. The conductor pattern was formed using thick film technology by screen printing a conductive paste and sintering it at high temperature. Furthermore, a resist pattern was formed on the conductor pattern to prevent short circuits during soldering.

Next, the bias resistor (3) and FET (4) components shown in the circuit diagram of FIG. 3 were attached to the back side of the wiring support board. If the conventional single-circuit FET shown in FIG. 3 were used to configure four circuits, a large space would inevitably be required.

Furthermore, when using one circuit of FETs, it is necessary to solder 12 terminals (3 terminals per circuit) x (4 FETs per circuit) = 12 terminals. On the other hand, as shown in Fig. 5, using a two-circuit FET (15) makes the space smaller (5 contact M terminals)
Only 10 terminals (2 FETs) are required, and the probability of defects due to disconnection, short circuits, etc. during connection can be reduced. Here, (16) represents a drain terminal, (17) represents two source terminals, and (18) represents two gate terminals.

Naturally, if a 3-circuit or 4-circuit FET is used, the effect in terms of space and yield will be large by combining these. Resistor (22) used in this example
was formed by immediately screen printing on the wiring support substrate (14).

The pyroelectric body (12) and the wiring support substrate (14) were connected using a support stand (23), and the cross section thereof was covered with a conductive adhesive. In the second case, an extraction hole for connection is imposed on the surface of the pyroelectric material by a vapor deposition pattern, and from this surface the support
＼ and connected with conductive adhesive. In 20 cases, each element/
A total of five supports were used, with the ground connection part of the gate being common, the III force gate connection part, and the ground connection part.

These equal force components are optical fnorter (24 mm with ears) (T Lf: T O-, 5-piece I-cage case (
25) and 6 hydraulic reeds 26゛: stem 12
It is electromagnetically shielded and hermetically sealed by 7.

: Rib 3 By taking purchase no k such as L'J, J-, 3
It is also possible to convert the pyroelectric infrared detection effect with a circuit or one detection circuit into a package corresponding to TO-) or to reduce the blind spot caused by the package to the same as US. It is possible to use the same optical system as the optical system.

In history, as ditches became simpler and easier to assemble, they became industrially valuable without significantly increasing costs.

[Brief explanation of drawings]

FIG. 1 shows the structure of the present invention. FIG. 2(a) shows a pattern diagram of a conventional dual element 11 circuit), and FIG. 2(b) shows a pattern diagram of a dual twin element 2 circuit). Figure 3 (a) and (b) are dual elements (1 circuit)
The circuit diagram is shown. In Figure 1, the center and bottom are the light receiving elements, and the outside is the temperature compensation element.
An element pattern diagram in which four circuits of this element are provided as a prize element is shown. Figure 5 shows the composite 2F used in the present invention.
The circuit diagram of ET is shown.

Claims (1)

[Claims] In a pyroelectric infrared detector that receives infrared rays and converts them into electrical signals, a 3- or 4-circuit detection circuit is constructed by using a composite FET (15) in which FETs of multiple circuits are housed in one. A pyroelectric infrared detector featuring: