JPH0511473Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention provides a passive moving object detector having a plurality of curved reflecting mirrors (preferably parabolic mirrors), and the shape of the mirror assembly while maintaining the efficiency of the plurality of reflecting mirrors. This is related to the simplification of .

Conventionally, an optical system used in a passive security alarm device, etc. has a plurality of mirrors arranged in an arc shape as shown in FIG. The mirror 12 is configured to focus radiant energy from a long distance, and the mirror 12 located near the limit of the viewing angle is configured to focus radiant energy from a relatively short distance. Since these mirrors are arranged in an arc shape, the area of each mirror has a certain limit if the focal lengths of all mirrors are kept constant.

In addition, the overall shape has a large depth d, resulting in a mirror with many irregularities, and in the case of mirrors manufactured by resin molding, there is an increase in distortion and defects that occur during processing processes such as aluminum vacuum deposition on the surface. There is a problem when there are too many. On the other hand, the second
A combination of mirrors as shown in the figure can be considered, but in order to focus the energy from the direction of the maximum angle b with respect to the central axis a, the width of the window W needs to be wide when viewed from the entire detector, which poses a problem. It is.

The present invention solves these problems, and an embodiment thereof is shown in FIG. Mirror 1 is defined as mirror 2, which focuses energy from the direction of optical axis b that has the maximum angle with respect to the optical axis of mirror 1 with respect to detection element P.
Place it on both sides of. A mirror 3 is placed next to the mirror 2 to focus energy in the direction of the optical axis c, which has an angle between the direction of the optical axis b and the direction of the optical axis a of the mirror 2.

By arranging it in this way, it is possible to obtain a higher surface area per image than in the conventional optical system when comparing detection elements having the same viewing angle. Also, the optical axis b having the maximum angle with respect to the central optical axis a
By placing the mirror with the mirror at a position close to the center, the surface area of the window portion can be reduced from the viewpoint of the entire detection device. Further, by appropriately adjusting the focal length of each mirror, the depth d of the entire mirror can be reduced. As a result, the entire mirror becomes nearly flat, and the probability of occurrence of defects in processing steps such as surface finishing can be reduced.

As described above, according to the present invention, not only a thin and efficient optical system is obtained and the entire device is miniaturized, but the entire mirror can be made into a shape with few irregularities, and molding and surface treatment are possible. This can lower the rate of defects in the process and contribute to reducing overall costs.

[Brief explanation of the drawing]

Figures 1 and 2 are explanatory diagrams of conventional optical systems;
The figure shows one embodiment of the present invention. P...Energy detection element, Q...Viewing angle.

Claims (1)

[Scope of utility model registration request] In a moving object detector equipped with a plurality of curved mirrors and radiant energy detection elements near the focal points of these curved mirrors, the optical axis that has the largest angle with respect to the optical axis a of the curved mirror 1 facing the radiant energy detection element Curved mirror 2 that focuses energy in the b direction is replaced by curved mirror 1.
An optical system is provided adjacent to the curved mirror 2 in order to converge energy from the optical axis direction whose angle with respect to the optical axis a is smaller than the optical axis b, and the entire optical system is made of resin. An optical system for a detector, characterized in that it is integrally molded and then mirror-finished.