JP3541959B2 - Scattered light smoke detector - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a scattered light smoke detector, and more particularly, to a scattered light smoke detector that prevents generation of useless reflected light caused by a change in an optical path due to dew condensation on the scattered light smoke detector. .
[0002]
[Prior art]
As a smoke detector, a scattered light type smoke detector is conventionally known.
FIG. 4 shows a vertical cross-sectional structure showing details of a smoke detection holder portion of such a scattered light type smoke detector. The light emitting element 100 and the light receiving element 101 are arranged so that light does not enter directly. And a light emitting element 100 is provided in a hole 102a formed on the light emission side of the smoke detection holder 102 and formed on the light receiving side opposite to the light emission side of the smoke detection holder 102. The light receiving element 101 is provided in the hole 102b with the prism lens 103 interposed therebetween.
[0003]
In such a scattered light type smoke detector, a portion where the optical axis of the light emitting element 100 and the light receiving element 101 intersect is configured as a smoke detection section S, and when smoke particles entering the smoke chamber enter this section, The scattered light is incident on the light receiving element 101 through the prism lens 103. At this time, the amount of light detected by the light receiving element 101 increases to a predetermined level, thereby notifying a fire.
[0004]
[Problems to be solved by the invention]
However, in such a scattered light type smoke detector, when the temperature suddenly changes in the room or when the air is blown during construction, water droplets adhere to the light emitting element or a part of the smoke room, and dew condensation occurs. Changes in the optical path of the light emitted from the light-emitting element cause unnecessary reflected light inside the smoke detector, which causes problems such as malfunctioning of the light-receiving element even though there is no intrusion of smoke. Has occurred.
[0005]
In view of the above, the present invention has been proposed in order to solve the problem. The purpose of the present invention is to prevent reflection inside the smoke detector even when an unnecessary optical path change occurs due to dew condensation. It is another object of the present invention to provide a scattered light type smoke detector having a high effect of preventing false alarms caused by dew condensation.
[0006]
[Means for Solving the Problems]
The scattered light type smoke detector according to claim 1, further comprising a smoke detector holder in which a light emitting element and a light receiving element are arranged and incorporated so as to form an angle at which light does not directly enter, and a light emitting side of the smoke detector holder. A light emitting element is provided in the hole formed in the light detecting element, and a light receiving element is provided in the hole formed on the light receiving side opposite to the light emitting side of the smoke detection holder with a prism lens interposed. In the scattered light type smoke sensor, a hole on the light emitting side has a relief hole formed downward, so that the light is emitted from the light emitting element due to dew condensation attached to the surface of the light emitting element, and the hole is formed. The reflected light of light directed downward is prevented from entering the prism lens .
[0007]
The present invention proposed in claim 2 is that, on the inner surface of the smoke detector holder, a partition wall is formed at the center, and an optical trap having a large number of irregularities is gradually bulged from the outer periphery toward the center partition wall. It is formed in a step shape so as to perform.
[0008]
Further, the present invention proposed in claim 3 is characterized in that a light-shielding plate is provided in the hole on the light-receiving side to cover the lower side of the prism lens.
According to a fourth aspect of the present invention, there is provided the scattered light type smoke detector according to the first to third aspects, further comprising a smoke chamber having a trap structure for inflowing smoke below the smoke detection holder, the bottom surface of the smoke chamber, is characterized in that a diffuse reflection surface that forms a large number of irregularities to prevent light reflection.
[0009]
[Action]
According to the scattered light type smoke detector according to claim 1 of the present invention, the light path changes due to the condensation formed on the surface of the light emitting element, and a part of the light is located below the hole where the light emitting element is mounted. Even if the light is emitted to the part, the part does not reflect because the relief hole is formed in that part. For this reason, it is possible to prevent unnecessary reflected light from being generated inside the smoke detector and entering the light receiving element.
[0011]
Furthermore, according to the scattered light type smoke detector of the second aspect , a partition wall is formed at the center of the inner surface of the smoke detection holder, and a large number of the walls are formed so as to gradually expand from the outer periphery toward the central partition wall. Since the light trap with the irregularities formed is provided, even if the light path changes due to the condensation formed on the surface of the light emitting element and some light is emitted to the ceiling surface, there are many irregularities in that part. Since the formed optical trap is provided, there is no reflection at that portion. For this reason, it is possible to prevent unnecessary reflected light from being generated inside the smoke detector and entering the light receiving element.
[0012]
Further, according to the scattered light sensor according to the third aspect, since the light shielding plate is provided below the prism lens, the light path changes due to dew condensation on the surface of the light emitting element, and a part of the light path is changed. Even if the light goes to the lower side of the lens, the light receiving element is not perceived as smoke even if the light receiving element is useless because the light shielding plate is provided at that portion.
Furthermore, according to the scattered light sensor according to the fourth aspect, the irregular reflection surface having a large number of irregularities for preventing light reflection is provided on the bottom surface of the smoke chamber. even if the light path is changed occurs, by reflecting light toward the bottom surface of the smoke chamber, since it is incident on the light receiving element is prevented, it is possible to prevent causing malfunction due unnecessary reflection.
[0013]
【Example】
Next, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing a main part of an embodiment of the scattered light type smoke detector according to the present invention.
In the scattered light type smoke detector A of the present invention, as shown in the figure, a smoke detection holder 1 is connected to an upper part of a smoke chamber 2a having a labyrinth structure peripheral wall (not shown).
[0014]
The smoke detector holder 1 is formed with a light emitting side hole 11 and a light receiving side hole 12 facing each other, and a light emitting element 2 composed of an LED or the like is embedded and attached to the light emitting side hole. I have. A prism lens 3 is fitted into the hole 12 on the light receiving side, and a light receiving element 5 in the form of an IC chip mounted on a circuit board 4 provided above the smoke detection holder 1 is provided on the light emitting side of the prism lens 3. The central axis of the light emitting element 2 and the central axis of the light entering side of the prism lens 3 are set in the smoke chamber 2a so that the light of the light emitting element 2 does not directly enter the prism lens 3 on the light receiving side. And crosses diagonally downward to form a smoke detection section B. Black paint is applied to the inner surface of the smoke chamber 2.
[0015]
An escape hole 6 is formed below the hole 11 formed on the light emission side of the smoke detection holder 1, and unnecessary light emitted from the light emitting element 2 is formed below the hole 12 on the light receiving side. A light-shielding piece 14 is provided so as not to be incident, and an upper part of the smoke detection holder 1 in which the prism lens 3 is fitted is opened, and the opening 13 is an IC mounted on a circuit board 4 constituting a control circuit of the sensor. It faces the light receiving element 5 in the form of a chip.
[0016]
On the inner surface of the smoke detector holder 1 serving as the inner surface of the smoke chamber 2a, partition walls 1a, 1a are projected at the center so that the light from the light emitting element 2 does not go to the ceiling surface but to the smoke detector B, and the periphery thereof is formed. An inclined surface 1b whose ceiling surface becomes higher toward the outside is formed.
In the smoke detector having such a structure, dew condensation occurs on the surface of the light emitting element 2, so that even if the optical path of the light emitted from the light emitting element 2 is directed below the light emitting side hole 11, the escape hole 6 is formed. Therefore, light is not reflected there, and therefore, the reflected light can be prevented from being incident on the prism lens 3.
[0017]
FIG. 2 is a longitudinal sectional view of a main part of the scattered light type smoke detector according to the present invention.
A structural feature of this smoke detector is that an optical trap 7 having a large number of irregularities 7a is provided below a light-emitting-side hole 11 to which the light-emitting element 2 is attached. As in the case of the escape hole 6, the light path changes due to dew condensation, so that reflection can be effectively prevented even when a part of the light goes to the lower side of the hole portion 11.
[0018]
FIG. 3 shows a vertical cross-sectional structure of a smoke detector in which the features of claim 1 are added to the features of claim 1.
That is, a relief hole 6 formed on the light emission side of the smoke detection holder 1 and below the hole 11 to which the light emitting element 2 is attached is formed to prevent reflection of light caused by dew condensation on the surface of the light emitting element 2. On the inner surface of the smoke detector holder 1, a partition wall 1a, 1a is protruded at the center, and a large number of irregularities 8a are formed in the periphery thereof so as to gradually expand from the outer periphery toward the center. The optical trap 8 is formed.
A light-blocking piece 14 is provided below the light entrance side of the prism lens 3 so that light emitted from the light-emitting element 2 and light reflected in the smoke chamber 2a do not enter the bottom of the smoke chamber 2a. , A large number of irregularities 9 a to form the irregular reflection surface 9.
[0019]
【The invention's effect】
According to the light scattering type smoke sensor according to claim 1 according to the present invention As apparent from the above description, the condensation occurring on the surface of the light emitting element 2, the scattered light is reflected by it an optical path It does not enter the light receiving element 5.
Further, according to the light scattering type smoke sensor according to claim 2, the light reflected on the partition wall 1a is not to enter the light receiving element 5 so that irregular reflection attenuated by irregularities 8a of the light trap 8.
[0020]
Furthermore, according to the light scattering type smoke sensor according to claim 3, since the prism lens 3 refracts the light receiving element 5 receives only light passing through the optical path, receiving the light scattered by condensation I will not do it.
Further, according to the scattered light type smoke detector of the fourth aspect , even if the light is scattered to the bottom of the smoke chamber 2a, it is irregularly reflected on the irregularities 9a of the irregular reflection surface 9 and attenuated, so that it does not enter the light receiving element 5. .
[Brief description of the drawings]
FIG. 1 is a schematic view showing a structure (claim 1) of a scattered light type smoke detector according to the present invention.
FIG. 2 is a longitudinal sectional structural view showing a main part structure (claim 2) of the scattered light type smoke detector according to the present invention.
FIG. 3 is a schematic view showing another structural example of the present invention (claims 3, 4, and 5).
FIG. 4 is a schematic vertical sectional view showing the structure of a conventional scattered light type smoke detector.
[Explanation of symbols]
A scattered light smoke detector B smoke detector 1 smoke detector holder 1a partition wall 2 light emitting element 4 prism lens 5 light receiving element 6 escape holes 7, 8 light trap 14 light shielding plate

Claims (4)

It has a smoke detector holder in which the light emitting element and the light receiving element are arranged and incorporated so that the light does not directly enter, and a light emitting element is provided in a hole formed on the light emitting side of the smoke detector holder, In the hole formed on the light receiving side opposite to the light emitting side of the smoke detection holder, a prism lens is interposed, and in a scattered light type smoke sensor having a light receiving element provided,
In the hole on the light emitting side , a relief hole is formed facing downward,
A scattered light smoke sensor , wherein reflected light of light emitted from the light emitting element and directed downward due to dew condensation on the surface of the light emitting element does not enter the prism lens . On the inner surface of the smoke detector holder, a partition wall is formed at the center, and an optical trap formed with a large number of irregularities is formed in a step shape so as to gradually expand from the outer periphery toward the center partition wall. The scattered light smoke detector according to claim 1. The scattered light type smoke detector according to claim 1, wherein a light shielding plate that covers a lower side of the prism lens is provided in the hole on the light receiving side. Below the smoke detecting holder, smoke chamber is provided in the trapping structure for flowing smoke on the bottom surface of the smoke chamber, and characterized in that a diffuse reflection surface that forms a large number of irregularities for preventing light reflection The scattered light type smoke detector according to any one of claims 1 to 3 .

Images