JP3338608B2 - Photoelectric smoke detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric smoke detector, and more particularly, to a light receiving element in a smoke sensing room which is free from light other than light scattered by smoke and is resistant to environmental changes such as temperature changes.
The present invention relates to a thin photoelectric smoke detector.

[0002]

2. Description of the Related Art In recent years, photoelectric smoke detectors also tend to be small and thin. The one shown in FIG.
The respective optical axes L1 and L2 of the light emitting unit 101 constituted by the ED and the light receiving unit 102 constituted by the prism lens are located on the same horizontal plane in the smoke sensing chamber 100, and both optical axes are the same. Unlike the structure in which the smoke detector is not arranged on a horizontal plane, the smoke detection chamber can be made thinner, so that the smoke detector can be made thinner as a whole.

However, in such a photoelectric smoke detector, light other than the scattered light due to the smoke that has entered the smoke detection chamber 100 also directly enters the light receiving unit 102, so that the light emitting unit 101 and the light receiving unit 102 Are arranged at a predetermined angle θ on the same horizontal plane, and the light emitting units 10
A disturbance light-shielding column 103 having two W-edges is formed between the light-emitting unit 101 and the light-receiving unit 102, and the disturbance light-shielding column 103 directly enters light from the light-emitting unit 101 to the light-receiving unit 102. This prevents light reflected on the labyrinth wall in the smoke sensing chamber 100 from entering the light receiving unit 102.

However, in such a structure, the light reflected on the labyrinth wall of the smoke sensing chamber 100 is further reflected on the light receiving portion side surface 103a of the W edge portion of the disturbance light shielding column 103 and enters the light receiving portion 102. In some cases, such disturbance light cannot be ignored as the ambient temperature increases and the output from the light emitting unit decreases. FIGS. 11 and 12 show changes in the output of the light receiving element with respect to the smoke density when the disturbance light N is large and when the disturbance light N is small.
Indicates output characteristics when the ambient temperature is normal temperature, and X 'indicates output characteristics when the ambient temperature increases and the amount of received light decreases.
It can be seen that the difference between the smoke density A and A ′ (A <A ′) increases as the disturbance light N increases.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has been made in consideration of the above circumstances, and has a photoelectric smoke detector in which a light emitting unit and a light receiving unit in a smoke sensing chamber are arranged so that their optical axes are located on the same horizontal plane. With the aim of providing a thin photoelectric smoke sensor that is less affected by changes in ambient temperature as a structure in which light other than scattered light in the smoke sensing room does not enter the light receiving unit. I have.

[0006]

The invention proposed to achieve the above object has the structural features proposed in claims 1-6. That is, in claim 1, L
A light-emitting part provided with a light-emitting element such as an ED and a light-receiving part provided with a prism lens that changes the optical path to the light-receiving element side and converges light are arranged to face each other at a predetermined angle on the same horizontal plane. Further, between the light-emitting part and the light-receiving part, a disturbance light-shielding column that blocks light directly entering from the light-emitting part to the light-receiving part is protrudingly provided, and a smoke sensing chamber having a labyrinth wall formed around the column. In the photoelectric smoke detector, a light trapping surface is further formed on the light receiving portion side of the first disturbance light shielding column to eliminate the reflected light at that portion.

According to a second aspect of the present invention, the optical trapping surface has a structure in which an optical trapping groove composed of a plurality of vertical grooves is formed. The light reflected on the side surface of the light-receiving portion of the first disturbance light-shielding column in the smoke sensing chamber is prevented from entering the light-receiving portion. Claim 4
Then, in claim 1 or 2, the smoke sensing chamber is an LED
The light path is changed to the light emitting element housing part for housing the light emitting element and the light receiving element side, and the optical base having the prism housing part for housing the prism lens for collecting light, and the light receiving element are surface-mounted. A light-emitting element, such as an LED, mounted thereon, a circuit board assembled to the optical base, and a labyrinth wall formed around the labyrinth wall and having one opening, and a light receiving element Has a structure that is directly surface-mounted on the circuit board without the intermediary of leads that are easily affected by thermal noise, so there is no electrical noise at the leads, making it less susceptible to thermal changes. .

According to a fifth aspect of the present invention, in the first or second aspect, in the vicinity of the light emitting portion, the light source is hidden behind the first disturbance light shielding column when viewed from the light receiving portion, and faces the light receiving portion from the light emitting portion. In order to prevent a light projection path from being formed on the labyrinth wall, another disturbance light-shielding column is protruded as a second disturbance light-shielding column, whereby reflected light from the labyrinth wall facing the light receiving portion is provided. Is prevented from directly entering the light receiving section.

According to a sixth aspect of the present invention, in any one of the first to fourth aspects, the predetermined angle at which the light-emitting portion and the light-receiving portion are opposed to each other can be set without lowering the sensitivity and without the influence of disturbance light. It is defined in the range of 120 degrees to 140 degrees confirmed by the experiments of the present inventors, and by defining the angle between the optical axis of the light emitting unit and the light receiving unit as described above, the light emitting unit and the light receiving unit are defined. Even when the optical axis is arranged on the same horizontal plane to reduce the thickness, it is possible to sufficiently detect scattered light due to smoke and hardly detect light scattered by other lights.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the photoelectric smoke detector according to the present invention will be described below with reference to the drawings. FIG. 1 shows a plane arrangement of a light emitting unit and a light receiving unit in a smoke sensing room. In the light emitting unit, 1 is provided with a light emitting element L such as an LED, and in the light receiving unit 2, a prism lens 21 is provided. , The light emitting unit 1 and the light receiving unit 2 are such that their respective optical axes L1 and L2 are 1 on the same horizontal plane.
They cross at an angle θ of 30 degrees.

Reference numeral 3 denotes a first disturbance light shielding support,
The length and the position of the support pillar 3 are defined so as not to hinder the light emission from the light emitting unit 1 and not to directly enter the light receiving unit 2 from the light emitting unit 1. In addition, smoke detection room S
A labyrinth wall 41 in which a plurality of wall pieces for allowing the invasion of smoke and preventing the invasion of external light are kept at appropriate intervals is formed around the wall.

FIG. 2 shows a detailed structure of the first disturbance light shielding column 3, in which a plurality of narrow vertical grooves 31a are formed on the side surface facing the light receiving section 2 to form an optical trapping surface 31. The light striking the surface 31 has a structure in which reflection is suppressed and absorbed. Such an optical trapping surface 31
May be a rough surface formed with fine irregularities instead of the vertical grooves.

FIGS. 3 and 4 are exploded perspective views of the sensor head of the photoelectric smoke sensor according to the present invention, and FIG. 5 is a longitudinal sectional structural view of the sensor head. As shown in FIG. 3, the optical chamber 10 is provided with a light emitting element serving as a light emitting element housing part on a circuit board 8 on which an LEDL serving as a light emitting element is mounted via a lead 81 and a PD serving as a light receiving element is surface mounted. Cover 51
And the prism housing 52 such that the respective optical axes are located on the same horizontal plane as described above, and furthermore, the optical base 5 on which the above-mentioned disturbance light shielding column 3 is projected.
Is covered from above. In such an optical chamber 10, a labyrinth wall 41 is formed around the optical chamber 10, and a labyrinth cylindrical body 4 having one end opened is covered to form a smoke sensing chamber S,
A connection hole (not shown) of the circuit board 8 configured as shown in FIG. 4 and attached to the back surface of the smoke detection chamber S configured as described above protrudes into the inner recess 72 of the sensor head 7. The smoke detecting chamber S is attached to the sensor head 7 and then the smoke detecting chamber S is covered with the protective gauge 6 to which the insect net 61 is attached.
Are fitted and connected to the sensor head 7 as shown in FIG. 5 to form a sensor head. In this figure, the sensing base is not shown, but is used by being attached to the ceiling surface by a method such as twist-fitting the sensor head 7 to the sensing base attached to the ceiling surface or the like.

FIG. 6 shows a second embodiment proposed in claim 5.
And the disturbance light-shielding column 9 is located closer to the light emitting unit 1 than the first disturbance light-shielding column 3 and is in the first position when viewed from the light-receiving unit 2. The light-shielding column 3 protrudes from the labyrinth wall 41 facing the light-receiving unit 2 and does not directly enter the light-emitting unit 2.

In the figure, the light projected from the light emitting hole 11 formed in the light emitting portion cover 51 constituting the light emitting element housing portion of the optical base 5 to the labyrinth wall 41 facing the light receiving portion 2 is shielded, and It is formed in a position behind the disturbance light shielding column 3 so that the reflected light from the labyrinth wall facing the light receiving unit 2 from the other labyrinth wall 41 of the sensing chamber 4 does not enter the light receiving unit 2. Its shape and dimensions are arbitrary,
In order to function as a light-shielding screen, it is preferable that the dimension be as long as possible.

FIG. 7 illustrates the light-shielding effect of the second disturbance light-shielding column 2. In the case where the second disturbance light-shielding column 3 is provided, a portion A of the labyrinth wall 41 that faces the light receiving section 2 is shown in FIG. Reflected light from the light receiving unit 2 can be prevented from directly entering the light receiving unit 2. That is, considering a light route that directly enters the light receiving unit 2 from the portion A of the labyrinth wall 41, the light flux P1 that has traveled straight from the light emitting unit 2 is reflected by the opposing labyrinth wall,
Further, there is a route P2 that goes straight to the portion A and a route P3 that goes straight from the edge of the light emission hole 11 of the light emitting portion 1 to the portion A of the labyrinth wall.
Is provided, the light path reflected from the portion A through these light routes is blocked, so that the light receiving section 2 does not receive the reflected light from the opposing portion A.

In the conventional smoke detector, in order to avoid light entering from the labyrinth wall facing the light receiving section, the light emitting section is formed as shown in FIG. May be accommodated in a dark box 200 provided with first and second apertures 201 and 202, or as shown in FIG.
Although the light emitting unit is housed in the light receiving unit 04 and the light emitted from the lens 205 is narrowed down into a beam shape by the lens 205, the second disturbance light shielding column is provided in the present invention without a complicated structure of the light emitting unit. And the structure can be simplified.

[0018]

As will be understood from the above description, the photoelectric smoke detector of the present invention has the following effects. According to the first, second, and third aspects, light incident on the light receiving element other than the scattered light due to smoke can be further reduced, so that a thin smoke detector that is resistant to environmental changes such as temperature changes can be obtained.

According to the fourth aspect, since the light receiving element is structured to be surface-mounted on the circuit board, a thin smoke detector which is resistant to electric noise in addition to environmental changes such as temperature changes can be obtained. Can be According to the fifth and sixth aspects, it is possible to provide a simple and inexpensive structure that does not allow the reflected light from the labyrinth wall to directly enter the light receiving unit while keeping the structure of the light emitting unit simple.

According to the seventh aspect, the light emitting section and the light receiving section are
When the respective optical axes are arranged so as to be located on the same horizontal plane, it is possible to provide a thin smoke detector which does not lower the sensitivity and is less affected by disturbance.

[Brief description of the drawings]

FIG. 1 is a diagram showing an arrangement relationship between a light emitting unit and a light receiving unit in a smoke sensing room of a photoelectric smoke detector according to the present invention.

FIG. 2 is an enlarged view of a first disturbance light shielding column.

FIG. 3 is an exploded perspective view of an optical chamber and a labyrinth cylinder in the sensor head of the photoelectric smoke detector according to the present invention.

FIG. 4 is an exploded perspective view showing a sensor head and a smoke detection chamber of the photoelectric smoke detector according to the present invention.

FIG. 5 is a vertical sectional structural view of a sensor head of the photoelectric smoke detector of the present invention.

FIG. 6 is an explanatory view showing an example of a second disturbance light shielding column.

FIG. 7 is an explanatory diagram of a light shielding effect of a second disturbance light shielding column.

FIG. 8 is a structural explanatory view of a light emitting unit in a conventional sensor in a case where a second disturbance light shielding column is not provided.

FIG. 9 is another structural explanatory view of a light emitting unit in a conventional sensor in a case where a second disturbance light shielding column is not provided.

FIG. 10 is a diagram showing an arrangement relationship between a light-emitting unit and a light-receiving unit of a conventional smoke sensor that has been made thinner.

FIG. 11 is an output characteristic diagram of a light receiving element showing a change in disturbance noise and smoke density at normal temperature.

FIG. 12 is an output characteristic diagram of the light receiving element showing disturbance noise and changes in smoke density when the ambient temperature increases.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light-emitting part 2 Light-receiving part 3 1st disturbance light shielding support | pillar 31 Optical trap surface 31a Optical trap groove L Light-emitting element (LED) PD light-receiving element S Smoke sensing room 4 Labyrinth cylinder 41 Labyrinth wall 5 Optical base 51 Light-emitting part cover (Light emitting element housing part) 52 Prism housing part 6 Protective cage 7 Sensor head 8 Circuit board 9 Second disturbance light shielding column 10 Optical chamber L1 Optical axis of light emitting part L2 Optical axis of light receiving part θ Predetermined angle

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeki Shimomura 1048 Odakadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works, Ltd. (56) References JP-A-7-121785 (JP, A) JP-A-7-72075 (JP, a) JP flat 7-182584 (JP, a) JP flat 5-303697 (JP, a) JitsuHiraku Akira 55-81749 (JP, U) (58 ) investigated the field (Int.Cl. ⁷ , DB name) G08B 17/107 G01N 21/53

Claims (7)

(57) [Claims] A light emitting unit provided with a light emitting element such as an LED;
The light path is changed on the light receiving element side, and a light receiving section provided with a prism lens for condensing light is opposed to the light axis at a predetermined angle on the same horizontal plane, and light is emitted between the light emitting section and the light receiving section. A first disturbance light shielding column for shielding light directly entering the light receiving unit from the light receiving unit, and a photoelectric smoke sensor having a smoke sensing chamber having a labyrinth wall formed around the first disturbance light shielding column. The photoelectric smoke detector has a structure in which a light trapping surface is formed on the light receiving portion side of the disturbance light shielding column. 2. The photoelectric smoke sensor according to claim 1, wherein the light trapping surface has a structure in which a light trapping groove formed by a plurality of vertical grooves is formed. 3. The photoelectric smoke detector according to claim 1, wherein the light trapping surface has a structure formed by roughening. 4. The smoke sensing chamber according to claim 1, wherein the smoke sensing chamber includes a light emitting element housing for housing a light emitting element such as an LED, and a prism for housing a prism lens for changing the optical path to the light receiving element and condensing light. An optical base having a housing and a light-receiving element mounted on the surface, a circuit board on which a light-emitting element such as an LED is mounted, and a labyrinth cylinder having a labyrinth wall formed on one side and an opening on one side. A photoelectric smoke detector configured in combination. 5. A labyrinth in the vicinity of the light emitting portion, which is hidden behind the first disturbance light shielding column when viewed from the light receiving portion, and which faces the light receiving portion from the light emitting portion. A photoelectric smoke detector having a structure in which a second disturbance light shielding column is further protruded so that a light path projected on a wall is not formed. 6. The photoelectric smoke sensor according to claim 5, wherein the second disturbance light shielding column is protruded from the vicinity of the light emitting section toward the labyrinth wall. 7. The method according to claim 1, wherein the predetermined angle at which the light emitting section and the light receiving section are opposed to each other is 12 °.
A photoelectric smoke detector that ranges from 0 degrees to 140 degrees.