JPS6381231A - Optical device for thermal detector - Google Patents

Abstract

PURPOSE:To obtain a thermal detector which has a caution area in a horizontal 360 deg. direction by guiding a horizontal heat ray incident on the entire 360 deg. periphery of a detector to the photodetection surface of a pyroelectric element by an optical path changing means. CONSTITUTION:Fresnel lenses 1 are arranged over the entire 360 deg. periphery at equal intervals as shown in a figure (a) and a pole 3 for standing a device body 2 on a floor surface is provided at the center bottom part of the device body 2. The respectively lenses 1 have their lens surfaces directed horizontally to have a visual field in the horizontal 360 deg. directions. Then, a reflecting mirror 4 whose reflecting surface slants downward slantingly is arranged circularly corresponding to the respective lenses 1 as shown in a figure (b) and the pyroelectric element 5 is arranged below the arrangement center of the reflecting mirror 4 so that the photodetection surface faces up. A heat ray incident on the lens 1 horizontally in parallel is reflected by the reflecting mirror 4 and converged on the element 5 at the focus position of the lens 1, so horizontally 360 deg. monitoring is possible about the thermal detector as the center.

Description

[Detailed description of the invention] [Technical field] The present invention relates to an optical device for a hot-wire type detector.

[Background Art] Conventionally, this type of hot wire detector is installed on a ceiling surface A as shown in FIG. As shown in Figure 9 (a), there is a cone-shaped warning area
) As shown in Figure 11, it is installed on the wall of the room.
Some had a warning area X that spread out in a fan shape diagonally downward from the installation point B, as shown in Figure (b).

However, in the past, there was no one that had a warning area in a 360° horizontal direction, and when monitoring a vast area, it was necessary to use a combination of multiple heat-ray detectors. .

[Object of the Invention] The present invention has been made in view of the above-mentioned points, and its purpose is to provide an optical system for a heat-ray detector that can set horizontal 360° as the warning area II of a single heat-ray detector. We are here to provide you with the equipment.

[Disclosure 1 of the Invention The present invention is a heat ray detector in which a light entrance surface is formed over the entire 360° circumference of the heat ray detector to receive the heat rays from the horizontal direction, and is arranged in a direction perpendicular to the horizontal direction. A plurality of 7-lens lenses focus the light on the light receiving surface of the pyroelectric element, and an optical path changing means directs the incident horizontal heat rays toward the light receiving surface of the pyroelectric element. It is characterized in that it is placed between the optical paths up to the light-receiving surface of the electronic element.

Figure 1 shows an overall perspective view of a hot wire detector using this embodiment. In this embodiment, Fresnel lenses 1 are arranged at equal intervals over the entire circumference of 360°, A ball 3 is provided at the center bottom of the vessel 2 to allow it to stand on the floor. Each Fresnel lens 1 has its lens surface facing in the horizontal direction, with a total of 7 Fresnel lenses, ? 1, it has a horizontal 360° field of view. Figure 2 shows a top view of this embodiment, and in the center of the vessel body 2, a reflecting mirror 4 whose radiation surface is directed diagonally downward is arranged in an I-knee circumferential shape so as to correspond to each Fresnel lens 1. , a pyroelectric element 5 is located below the center of the arrangement of these reflections @4.
is arranged with the light-receiving surface facing upward.

Fig. 3 shows the relationship between the optical system of the Fresnel lens 1, the reflecting mirror 4, and the pyroelectric element 5. The light is focused on a pyroelectric element 5 whose light-receiving surface is placed exactly at the focal position of the pyroelectric element 5.

Therefore, the heat rays entering from each Fresnel lens 1 are focused on the pyroelectric element 5, and the heat rays are focused on the pyroelectric element 5, and horizontally
This allows for monitoring in the ° direction.

Figure VI4 shows an example of an arrangement in which this embodiment is placed in the center of a room, standing on its own at about the height of a person. Monitoring is possible.

In the example, the hot wire type detector is made to stand on the floor using the ball 3, but it may be built into a lighting fixture that is suspended from the ceiling, or the hot wire type detector itself may be placed above the ceiling at the height of a person. It may also have a hanging structure.

In the first embodiment described above, the heat rays entering from the Fresnel lens 1 are reflected by the reflecting mirror 4, the optical path is bent, and the light is focused on the light-receiving surface of the pyroelectric element 5. However, this embodiment In this case, instead of the reflecting mirror 4, a Fresnel lens is used as the prism 6 to refract the heat rays entering from the horizontal direction, and then the Fresnel lens 1' focuses the light onto the light receiving surface of the pyroelectric element 5. Fig. 5 shows a cross-sectional view of a hot wire type detector using this embodiment. A Fresnel lens 1' is disposed corresponding to each prism 6, and the heat rays refracted by the corresponding prism 4 are condensed onto the upward light-receiving surface of the pyroelectric element 5 disposed below the center. In this embodiment, Fresnel lenses 7 are arranged to make the upper direction of the heat ray detector a warning area, and the heat rays entering each Fresnel lens 7 are directly focused on the light receiving surface of the pyroelectric element 5. It is designed to illuminate. In other words, in this embodiment, not only the horizontal 360° direction but also the upward direction is set as the warning area.

FIGS. 6(a) and 6(b) show a front view and a side view of the prism 6 used in this example.
This is a device in which a plurality of straight grooves 6a are arranged in parallel to form a plurality of convex portions having a triangular cross section, and as shown in Fig. It is designed so that it comes out in parallel.

[Effects of the Invention] The present invention forms a light entrance surface that receives the heat rays from the horizontal direction over the entire #1360° of the hot ray detector, and has a focal point that is oriented perpendicularly to the horizontal direction. A plurality of Fresnel lenses focus the light on the light receiving surface of the pyroelectric element, and an optical path changing means bends the optical path to direct the incident horizontal hot rays toward the light receiving surface of the pyroelectric element. Since it is placed between the optical paths to the surface, it is possible to realize a heat-ray detector with a 360° horizontal warning area, and as a result, it is possible to monitor a vast warning area with a single heat-ray detector. It has the effect of becoming.

[Brief explanation of the drawing]

@ Figure 1 is a perspective view of the hot wire type detector of Example 1 of the present invention, Figure 2 is a top view of the same as the above, Figure 3 is a diagram explaining the principle of the same, and Figure 4 is the same as the above.
The figure shows an example of the arrangement of the same hot wire detector as above. Figure 5 is a cross-sectional view of the main part of Embodiment 2 of the present invention, and Figure 6 (
a) and (b) are a front view and a side view of the prism used as above,
FIG. 7 is an explanatory diagram of the operation of the prism used in the above, and FIGS. 8 to 9 are explanatory diagrams of the conventional example. 1... Fresnel lens, 4... Reflecting mirror, 5... Pyroelectric element. Agent Patent attorney Ishi 1) Ai 7th 1 Figure 1... Fresnel lens 4... Reflector Figure 6 1i7

Claims (3)

[Claims] (1) A light-receiving surface of a pyroelectric element that forms a light entrance surface that receives heat rays from the horizontal direction over the entire 360° circumference of the hot-wire detector, and is arranged in a direction perpendicular to the horizontal direction. A plurality of Fresnel lenses are used to focus the incident horizontal heat rays onto the light receiving surface of the pyroelectric element, and an optical path changing means that bends the optical path toward the light receiving surface of the pyroelectric element An optical device for a heat ray detector, characterized in that the optical device is arranged in a. (2) The optical device for a hot-wire type detector according to claim 1, characterized in that a reflecting mirror is used as the optical path changing means. (3) The optical device for a hot-wire type detector according to claim 1, characterized in that a prism is used as the optical path changing means.