JPH07120478B2 - Scattered light smoke detector - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a scattered light smoke detector used in a fire alarm device and detecting smoke from a fire.

[Prior Art] Conventionally, scattered light smoke detectors used in fire alarm devices are
A light emitting element irradiates a light beam into a dark box into which outside air can flow, and the light receiving element detects scattered light due to the smoke irradiated on the light beam to catch the smoke. This scattered light type smoke detector is, for example, as disclosed in Japanese Utility Model Publication No. 58-40477, an element support stand or the like so that the optical axes of the light emitting element and the light receiving element are directed to the smoke detection area in the dark box. It is supported and fixed by. Also, the light beam of the light emitting element does not immediately enter the light receiving element, and the diffuse reflection on the inner surface of the dark box is prevented as much as possible.

[Problems to be Solved by the Invention] A conventional scattered light type smoke sensor has a structure in which an optical system such as a light emitting and receiving element is uneven in a dark box. Due to such a structure, the flow of the outside air inflow becomes complicated, which causes directionality and delays in detection time. Further, there is a limit to downsizing due to such a configuration of the optical system. Also, since the optical axis adjustment of the optical system is delicate, there are large variations in products,
In addition, the stray light caused by external light deteriorates the S / N ratio, so that the emission intensity of the light emitting element is increased and an amplifier with a large amplification factor for amplifying the detection signal of the light receiving element is required.

[Means for Solving the Problem] The scattered light type smoke detector of the present invention is provided with a dark box which allows free circulation of outside air and prevents outside light from entering, and prevents smoke that has entered the smoke detection area in the dark box. In a scattered light smoke detector that detects from scattered light, a light emitting element that emits a light beam of a specific wavelength,
A first reflection hologram element that reflects the light beam of the light emitting element toward the smoke detection area through a waveguide layer, and a scattered light due to smoke in the smoke detection area is received, and a predetermined amount is received through the waveguide layer. A second reflection-type hologram element that collects light in a direction, and the second reflection-type hologram element.
And a light receiving element provided at the condensing position of the reflection type hologram element, the light emitting element, the light receiving element, the waveguide layer, the first reflection type hologram element, and the second reflection type hologram on the substrate. Characterized in that a plate-shaped optical element is formed by arranging each of the elements individually, and the plane of the plate-shaped optical element is parallel to the smoke inflow direction in the dark box. It is what

[Operation] By constructing the optical system of the scattered light smoke detector on a substrate and using a reflection hologram element, the detector can be downsized and is not affected by noise light. S /
A detection signal with a good N ratio can be obtained.

[Embodiment] An embodiment of the scattered light type smoke detector of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment of the scattered light type smoke sensor of the present invention, FIG. 2 is a plan view showing the optical element of FIG. 1, and FIG. 3 is a plan view of FIG. .

The scattered light type smoke detector of the present invention includes a body 1, a dark box 2 in which a plurality of holes are provided in the body 1 so that the outside air can freely flow and the outside light does not enter, and one side of the dark box 2 is provided. It is composed of an optical element 3 arranged and an electric circuit component for processing a signal from the optical element 3, and a printed circuit board 4 fixedly supported by the body 1. As shown in FIGS. 2 and 3, the optical element 3 is a light emitting element 31 arranged on a Si (silicon) substrate 30 for emitting coherent light of a specific wavelength.
A waveguide layer 32 that guides the light beam from the light emitting element 31 in a direction parallel to the thickness direction and a light beam from the waveguide layer 32 in the direction of the smoke detection area 21 in the dark box 2. 1 reflection hologram element 33, a second reflection hologram element 34 that receives scattered light from smoke from the smoke detection area 21 and focuses it in a predetermined direction, and reflection from the second reflection hologram element 34 The waveguide layer 35 that guides the light and the light receiving element 36 that detects the scattered light of smoke through the second reflection hologram element 34 and the waveguide layer 35 are integrated into a plate shape. First and second
The reflective hologram elements 33 and 34 are formed by cutting a glass (optical plastic) or the like at a predetermined angle to form a hologram pattern.

The light beam emitted from the light emitting element 31 passes through the waveguiding layer 32 and is first
Reaching the reflective hologram element 33. The light emitting element 31 emits a coherent light beam having a predetermined wavelength.
By utilizing the diffraction phenomenon of the hologram pattern formed on the hologram element 33, it is possible to reflect a light ray of a specific wavelength in a specific direction, and the reflection direction of each light ray incident on each part of the hologram pattern is defined as a smoke detection area. A hologram pattern is formed by calculating so as to face 21. Further, the light scattered by the smoke in the smoke detection area 21 is received by the second reflective hologram element 34, and a hologram pattern is similarly formed so as to be condensed on the light receiving element 36 via the waveguide layer 35. In this way, when smoke is generated outside, it enters from around the dark box 2 (on the left and right sides of the body 1) and flows toward the smoke detection area 21 at the center of the dark box 2 (smoke inflow direction). The smoke (concentration) that has entered the inside can be detected as a detection signal of the light receiving element 36, and predetermined processing is performed by the processing circuit mounted on the printed board 4 and output to the outside.

[Effects of the Invention] The scattered light type smoke sensor of the present invention has a plate-shaped optical element 3 arranged on one side surface parallel to the smoke inflow direction in the dark box 2 so that a light receiving element 31 is provided in the smoke detection area 21. It emits light rays and can receive scattered light due to smoke, and since the plane of the plate-shaped optical element 3 is arranged parallel to the smoke inflow direction, it is smooth against smoke inflow and the direction It has the effect of improving sex and time delay. Further, since the optical system including the light emitting element 31 and the light receiving element 36 can be formed in a small size in the optical element 3, the size of the entire sensor can be reduced.
Further, since there is no optical adjustment, manufacturing of the product and quality control are easy, and cleaning is easy because the structure in the dark box is relatively simple.

The amount of external light entering from the outside of the sensor and diffuse reflection in the dark box 2 by the light emitting element 31 enters the light receiving element 36, only the light beam incident on the light receiving element 36 at a predetermined angle of a specific wavelength reaches the light receiving element 36. Therefore, it is extremely small, that is, the S / N ratio can be improved, the smoke detection signal can be large, and there is no need to increase the light emission intensity of the light emitting element 31 and the amplification factor of the amplifier for amplifying the detection signal of the light receiving element 36. Have.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of the scattered light type smoke sensor of the present invention, FIG. 2 is a sectional view showing the photoelectric element of FIG. 1, and FIG. 3 is a second plan view. 1 ... Body, 2 ... Dark box, 3 ... Optical element, 4 ... Printed circuit board, 21 ... Smoke detection area, 30 ... Substrate, 31 ... Light emitting element, 32, 35 ... Waveguide layer, 33 ... 1st reflective hologram element, 34 ... 2nd reflective hologram element, 36 ... light receiving element.

Claims (1)

[Claims] 1. A scattered light type smoke sensor for detecting smoke that has entered a smoke detection area in the dark box from scattered light by providing a dark box which allows free circulation of outside air and prevents outside light from entering. A light emitting element that emits a light beam of a wavelength, a first reflection hologram element that reflects the light beam of the light emitting element toward the smoke detection area through a waveguide layer, and a scattered light due to smoke in the smoke detection area. A second reflection-type hologram element that receives light and collects light in a predetermined direction via the waveguide layer; and a light-receiving element provided at the light-collection position of the second reflection-type hologram element,
A light-emitting element, a light-receiving element, a waveguiding layer, a first reflection-type hologram element, and a second reflection-type hologram element are arranged on a substrate to form an integrated plate-shaped optical element, A scattered light type smoke detector characterized in that the plane of the plate-shaped optical element is arranged parallel to the smoke inflow direction in the dark box.