JPH0330954Y2 - - Google Patents

Description

[Detailed description of the invention] This invention allows light emitted from a light projector into a smoke monitoring space in a dark box that can communicate with outside air to prevent scattered light caused by smoke entering the smoke monitoring space. The present invention relates to a scattered light type smoke sensor that detects the presence of smoke by receiving light with a light receiving section provided outside the radiation area.

This scattered light, which is scattered in the forward direction with respect to the radiation direction of the light emitted from the light projecting part, has strong radiation intensity and weak radiation intensity depending on the type of smoke. Scatter in the opposite direction, that is, backwards, does not vary as much as in the forward direction, but its radiation intensity is weak regardless of the type of smoke, so it can effectively detect all types of smoke. In order to achieve this, it is desirable to maintain a balance between these and receive scattered light substantially perpendicular to the radiation direction.

Therefore, in order to receive such scattered light directly, the light-receiving section must be placed at a nearly right angle to the radiation direction. In order to cover the radiation area of the smoke monitoring space, the light receiving section must be provided at a certain distance from the radiation area, which has the disadvantage of increasing the size of the dark box.

Therefore, in consideration of the above points, the present invention provides a lens on the front surface of this light projecting part so that the radiation area of the light emitted from the light projecting part is parallel in one cross section along the radiation direction in the smoke monitoring space. is deformed into a shape, and with respect to the above radiation direction in the smoke monitoring space,
A convex lens is provided outside the radiation area in the cutting direction of the cross section to condense the scattered light to the light receiving part so that all the scattered light at almost right angles is parallel, and its optical axis is approximately parallel to the radiation area. , is provided eccentrically from the center of the scattered light transmitting region of the convex lens, and the light receiving section is provided at the focal point of the convex lens, so that the dark box can be made small.

Hereinafter, an embodiment of the present invention will be explained with reference to the drawings. First, as shown in FIGS. 1 and 2, a dark box 1
is composed of upper and lower cover plates 2, 3 and a plurality of side wall plates 4, and a dark box is provided with appropriate intervals between the cover plates 2, 3 and the side wall plates 4, and between each side wall plate 4. It has an optically blocked ventilation hole 5 that communicates between the inside and outside of 1,
Inside this dark box 1, a light projector 6 is arranged on the inner surface of one side wall plate 4, and a lens 9 is disposed on the front surface thereof to transform the radiation area 7 into a parallel shape in a longitudinal front view of the smoke monitoring space 8, and the opposite side wall Provided towards plate 4,
A convex lens 10 is provided above and outside of the radiation area 7 in the smoke monitoring space 8, substantially parallel to the radiation area 7.

Note that this convex lens 10 is a Fresnel lens, and its optical axis is located at the smoke monitoring space 8.
It is set on the light projecting section 6 so that the scattered light caused by the smoke entering the inside is outside the area where the convex lens 10 passes through.

Also, a light receiving section 11 is placed at the focal point of this convex lens 10.
However, the front side thereof is surrounded by a smoke shielding plate 12. Note that FIGS. 3 and 4 show other embodiments, but the difference from the embodiments in FIGS. A convex lens 10', a light receiving section 11' and a smoke shielding plate 12' are symmetrically provided at the bottom across the space 8, and the radiation area 7 is used for smoke monitoring instead of the lens 9 in front of the light projecting section 6. The point is that a lens 9' is provided in the space 8 to be deformed into a flat fan shape that is thin in the vertical direction and wide in the horizontal direction.

Next, the operation will be explained. Light is always emitted from the hole casting part 6 into the smoke monitoring space 8 inside the dark box 1.

Therefore, when smoke enters the smoke monitoring space 8, the light emitted from the light projector 6 is scattered by the smoke, and among the light scattered upwardly at a angle approximately perpendicular to the radiation direction (see Figs. ), or the upward and downward scattered light (Figs. 3 and 4) are all transmitted through the convex lens 10.
(Figures 1 and 2) or convex lenses 10, 10'
(Figs. 3 and 4) and is focused on the focal point of the light receiving part 11 (Figs. 1 and 2) or the light receiving part 11,
11' (Figures 3 and 4).

In this case, as mentioned above, the front surfaces of the light receiving sections 11, 11' are surrounded by the smoke shielding plates 12, 12', so the scattered light transmitted through the convex lenses 10, 10' is not blocked by other smoke. . In this way, in the present invention, the light receiving parts 11, 11' are the convex lenses 10, 11',
Since it is provided at the focal point of the light receiving section 11,
The scattered light condensed at 11' is only scattered light substantially perpendicular to the radiation direction.

The lens 9' includes, for example, a concave part 13 and a convex part 14, which are formed on the back surface and the front surface, respectively, and whose axes of curved surfaces are orthogonal to each other, and the light emitted from the light projecting part 6 is By passing through the concave surface portion 13 and the convex surface portion 14, the radiation region 7 is deformed into a flat fan shape in the smoke monitoring space 8.

In addition, in the present invention, a convex lens 10 that condenses the scattered light to the light receiving section 11 is placed on the outside of the radiation region 7 in the smoke monitoring space 8 of the light emitted from the light projecting section 6 so as to be substantially parallel to the radiation region 7. However, in this embodiment, the convex lens 10 has its optical axis set outside the region through which the scattered light passes through, so that all the scattered light is refracted in the same direction when transmitted through the convex lens 10. Since the light is focused on the focal point, if the light receiving section 11 is provided at the focal point, all the scattered light that is substantially perpendicular to the radiation direction in the smoke monitoring space 8 will be focused on the light receiving section 11.
Moreover, since the direction of the light receiving section 11 is at an acute angle with respect to the radiation area 7, the light receiving angle can be narrow, and the distance between the light receiving part 11 and the radiation area 7 can be shortened, so that the dark box 1 can be made smaller. convenient.

In addition, as shown in FIGS. 3 and 4, the convex lens 1
If the light receiving sections 11 and 11' are provided on both sides of the smoke monitoring space 8, the sensitivity will be improved because scattered light in both directions can be received at the same time. Furthermore, in the case where the radiation region 7 is transformed into a parallel shape by a simple lens 9 as shown in FIGS. 1 and 2, the radiation region 7 is thick in the vertical direction and narrow in the horizontal direction. Even if insects, dust, etc. enter, most of the light emitted from the light projector 6 will be reflected in the same way as light scattered by smoke, which may cause malfunction.
Furthermore, there is a risk that the light scattered by the smoke will be blocked by other smoke and will not be received, resulting in a false alarm. However, as shown in FIGS. 3 and 4, a special lens is used on the front surface of the light projector 6 to transform the radiation area 7 into a flat fan shape that is thin in the vertical direction and wide in the horizontal direction in the smoke monitoring space 8. 9' eliminates the above-mentioned drawbacks.

Note that if the optical axes of the convex lenses 10, 10' are set outside the transmission area of the scattered light in the convex lenses 10, 10' as in the embodiment, the optical axes will be far from the center of the transmission area. Since the light receiving portions 11 and 11' are eccentric, the light receiving angle of the light receiving portions 11 and 11' can be narrower as described above, and the light receiving portions 11 and 1
Although the distance between 1' and the radiation region 7 can be shortened,
If this optical axis is decentered from the center even within the transmission region of the scattered light, the effect will be sufficient, although not as much as when it is outside the transmission region.

Furthermore, if Fresnel lenses are used as the convex lenses 10 and 10' for condensing the scattered light onto the light receiving sections 11 and 11', as in the embodiment, the thickness can be made extremely thin, so that the dark box 1 can be made smaller. However, the above effect can also be utilized by using a normal spherical lens.

Furthermore, in the embodiments shown in FIGS. 3 and 4, in addition to the embodiments shown in FIGS. In addition, lenses g' are provided on both sides of the upper and lower sides, and lenses g' are provided on the front surface of the light emitting unit 6 to transform the radiation area 7 into a flat fan shape in the smoke monitoring space 8. can be configured by appropriately combining them.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention;
Figure 2 is a cross-sectional view of the - line part in Figure 1;
The figure is a longitudinal cross-sectional view showing another embodiment of the present invention, and FIG. 4 is a cross-sectional view taken along the - line in FIG. 3. 1... Dark box, 2, 3... Lid plate, 4... Side wall plate,
5... Ventilation hole, 6... Light projecting section, 7... Radiation area,
8...Smoke monitoring space, 9,9'...Lens, 10,
10'... Convex lens, 11, 11'... Light receiving section, 1
2,12'...Smoke board.

Claims (1)

[Scope of claim for utility model registration] 1. A smoke monitoring space 8 in a dark box 1 that can communicate with outside air.
and a light projector 6 that emits light into this smoke monitoring space 8.
and a light receiving section 11 provided outside the radiation area, and detects the presence of smoke by receiving scattered light generated by smoke entering the smoke monitoring space 8 with the light receiving section 11. In the scattered light type smoke detector, a lens 9 is provided on the front surface of the light projection unit 6 to deform the radiation area 7 into a parallel shape in a cross section along the radiation direction in the smoke monitoring space 8, and A convex lens 10 that condenses the scattered light onto the light receiving section 11 is placed outside the radiation area 7 in the cutting direction, approximately parallel to the radiation area 7, and its optical axis is from the center of the area through which the scattered light passes through the convex lens 10. A scattered light type smoke detector characterized in that the light receiving section 11 is provided eccentrically at the focal point of the convex lens 10. 2 The lens 9 provided on the front surface of the light projecting unit 6 makes the radiation area 7 thin in the cutting direction of the cross section in the smoke monitoring space 8, and wide in the shape of a flat fan in other cross-sectional directions orthogonal to the above-mentioned cross-sectional direction. The scattered light type smoke detector according to claim 1 of the claimed utility model registration, which is capable of being transformed. 3. The scattered light type smoke detector according to claim 2, wherein the lens 9 includes a concave portion and a convex portion whose axes of curved surfaces are orthogonal to each other. 4 Convex lens 1 that focuses the scattered light onto the light receiving section 11
4. The scattered light type smoke sensor according to any one of claims 1 to 3, wherein the optical axis of the convex lens 10 is set outside the transmission area of the scattered light. 5. The scattered light smoke detector according to any one of claims 1 to 4, wherein the convex lens 10 is a Fresnel lens. 6 Convex lenses 10, 10' and light receiving sections 11, 1
1' are provided on both sides of the smoke monitoring space 8. The scattered light type smoke detector according to any one of claims 1 to 5 of the claims 1 to 5, which is a registered utility model. 7. The scattered light type smoke detector according to any one of claims 1 to 6, which has a smoke-shielding structure on the front surface of the light-receiving parts 11, 11'.