JPH0421084Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a composite pyroelectric infrared detection device.

Pyroelectric infrared sensors are easier to handle than other optical sensors because they do not require a light emitting part.
Recently, it has been gaining popularity in applications such as automatic doors and security devices. However, in this type of pyroelectric infrared sensor, since the pyroelectric element is constructed with high impedance, it generates various kinds of unique noises, and these noises can be a hindrance when expanding the monitoring angle or extending the capture distance. There are a wide variety of drawbacks. For this reason, methods have been taken to deal with noise by increasing the signal level by increasing the aperture of the reflector, but increasing the aperture of the reflector does not make it possible to downsize the entire device. , and has disadvantages such as being expensive.

The present invention was devised to eliminate the above-mentioned drawbacks, and consists of a composite pyroelectric infrared ray in which a substrate made of a conductor is used as a common back electrode, and at least two pyroelectric elements are attached back to back to the back electrode. It provides a detection device that improves the output S/N without increasing the aperture of the reflecting mirror.
Therefore, it is possible to downsize the device.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a partially sectioned side view showing the main parts of a composite pyroelectric infrared detection device according to the present invention, and numerals 1 and 2 indicate pyroelectric elements made of a suitable pyroelectric material. Pyroelectric elements include the so-called single type with one detection section, the so-called dual type with two detection sections, and the so-called dual twin type with four detection sections, but any type can be used. It is often shown generally in the drawings. 3 indicates a conductive substrate suitably selected from a series of metal conductors such as Fe, Al, Cu, etc., and this substrate 3 constitutes a common back electrode for the pyroelectric elements 1 and 2; Pyroelectric elements 1 and 2 are arranged back to back to face each other. In this embodiment, auxiliary films 4 are deposited on both surfaces of the substrate 3 by electroplating, electroless plating, vapor deposition, etc., and the pyroelectric elements 1,
2 is fused to this auxiliary film 4 to form a substrate 3.
The pyroelectric elements 1 and 2 are mounted in close contact with the substrate 3 and electrically connected to the substrate 3 via the auxiliary film 4, and the pyroelectric elements 1 and 2 are thermally closely coupled to the substrate 3. That is, as the auxiliary film 4, Ni,
From a series of metals such as Zn, Pu, Cu, Au, and Sn, metals that have good fusion characteristics with the electrodes provided on the back surfaces of the pyroelectric elements 1 and 2 and also have good electrical characteristics are appropriately selected. It is used as an alloy. Lead wires 5 and 6 for extracting electrical signals are connected to each pyroelectric element 1 and 2, respectively, and electrical signals corresponding to the amount of incident infrared rays are transmitted from these lead wires 5 and 6 to the conductor. The signal is sent to an external electric circuit (not shown) using the substrate 3 as a return line. Note that a through hole 7 is formed in the base of the substrate 3 for attaching an external connection terminal. The composite pyroelectric infrared detection device is implemented as shown in FIG. In FIG. 2, reference numeral 11 indicates a concave mirror having a metal or resin surface treated with a metal film. Substrate 3 is inserted through the concave mirror 11 at approximately the center thereof and is electrically and thermally coupled to the metal film of the concave mirror 11 . With this configuration, the heat of the substrate 3 is transferred to the concave mirror 11.
spread to. In this case, the pyroelectric elements 1 and 2 are placed almost at the focal point of the concave mirror 11, and the incident infrared rays H ₁ and H ₂ are directed to the corresponding pyroelectric elements 1 and 2.
It is configured to focus on the pyroelectric surface of. Further, external connection terminals 12 are attached to the through holes 7 of the substrate 3 arranged outside the concave mirror 11 by appropriate means. Lead wires 5 and 6 of each pyroelectric element 1 and 2 are internally connected to through terminals 13 and 14 provided separately on the concave mirror 11. External lead wires 15 and 16 are connected to these through terminals 13 and 14, respectively, and electrical output signals sensitive to incident infrared rays are transmitted through these external lead wires 15 and 16.
The lead wires 17 connected to the external connection terminals 12 are used as a common return wire, and are each independently supplied to an external electric circuit (not shown).

Since the present invention is configured as described above, the amount of infrared rays incident on the pyroelectric element can be increased without increasing the aperture diameter of the reflecting mirror, improving the output sensitivity. Since the pyroelectric element is brought into close contact with the substrate and the reflector is thermally coupled, the heat dissipation effect from the pyroelectric element is improved, and the response to incident infrared rays is significantly improved. Therefore, noise components generated due to thermal disturbance within the pyroelectric element are reliably reduced, and an output signal with a good S/N ratio can be obtained. In addition, the shape of the reflecting mirror can be made smaller to improve the S/N ratio, and therefore a small and inexpensive infrared detection device can be easily obtained, so the demand for this type of infrared detection device will continue to increase in the future. When applied to various types of equipment using the present invention, remarkable effects such as ease of incorporation and installation, improved performance, and miniaturization of the entire equipment can be obtained.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway side view showing the main parts of a composite pyroelectric infrared detection device according to the present invention, and FIG. 2 is a schematic cross-sectional view showing an example of mounting the pyroelectric infrared detection device. In the figure, 1 and 2 are pyroelectric elements, 3 is a conductive substrate, and 11 is a concave mirror.

Claims (1)

[Scope of utility model registration request] A concave mirror having a metal surface, a substrate made of a conductor that is thermally coupled to the concave mirror and attached through the concave mirror at approximately the center thereof, and the substrate is placed back to back on the substrate using the substrate as a common back electrode. 1. A composite pyroelectric infrared detection device comprising at least two attached pyroelectric elements.