JP2004220225A - Scattered light type smoke sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the influence of the adhesion of dust and lint to the vicinity of the openings of a light emitting part and a light receiving part embedded at a mounting face side with respect to a smoke detecting space on the light receiving part to the minimum. <P>SOLUTION: A scattered light type smoke sensor is configured by embedding a light emitting part and a light receiving part at a mounting face side by providing an opening without projecting them in a smoke detecting space, and arranging the light emitting part and the light receiving part so that an optical axis from the light emitting part directed to the smoke detecting space can cross the optical axis of light scattered by smoke particles in the smoke detecting space and directed to the light receiving part at a predetermined angle in a horizontal direction and at a predetermined angle in a vertical direction. In this case, the opening shapes at the facing side of the respective openings 9 and 10 of the light emitting part and the light receiving part are constituted as a portion of roughly ellipsoidal shapes. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a scattered light smoke sensor that detects a fire by receiving light scattered by smoke particles in a smoke detection space that flows in from the outside.
[0002]
[Prior art]
Conventionally, as this type of scattered light type smoke detector, for example, there is one shown in FIG. 12 (Patent Document 1). In FIG. 12A, a cover 102 is attached to a lower part of the sensor main body 100, and a smoke detection space 103 into which smoke flows is formed. A holder 104 is mounted on the sensor body 100 side in the smoke detection space 103, and the light emitting unit 106 and the light receiving unit 108 are housed in the holder 104 via openings 110 and 112.
[0003]
In this structure, as shown in FIG. 12B, the light emitting unit 106 emits light in the direction of the optical axis 114 and receives scattered light caused by the light hitting the flowing smoke from the direction of the optical axis 116. The light is received by the unit 108.
[0004]
Here, the light emitting unit 106 and the light receiving unit 108 are arranged such that the optical axes 110 and 116 obliquely intersect on a virtual horizontal plane in the sensor, and the scattering angle θ of the optical axis intersection 118 is set to a predetermined angle. ing. Here, the intersection angle δ of the optical axis, which is a complementary angle to the scattering angle θ, is called a constituent angle, and has a relationship of θ = 180 ° −δ.
[0005]
Further, two light shielding plates 120 and 122 are disposed therebetween, and the light shielding plate 120 blocks direct light toward the light receiving unit 108, and the next light shielding plate 122 reflects reflected light of light that has hit the front end of the light shielding plate 120 on the near side. An optical trap for blocking is formed.
In this conventional structure, as shown in FIG. 12A, the optical axis of the light emitting section 106 and the light receiving section 108 is directed downward by about 3 ° to 5 °, and the optical axis intersection is formed on the upper surface of the smoke detection space 103. It is adjusted so that it does not get too close to.
[0006]
However, in the structure of such a conventional scattered light smoke detector, the light emitting unit 106, the light receiving unit 108, the light shielding plates 120, 122, and the like protrude into the smoke detection space 103 into which the smoke inside the detector flows. Therefore, there is a problem that there is a high possibility that the inflow of smoke from the outside has a direction.
[0007]
Therefore, a scattered light type smoke detector as shown in FIG. 13, for example, is known in order to prevent the flow of smoke into the smoke detection space 103 from having a direction (Patent Document 2).
[0008]
In FIG. 13, a cover 202 is attached to a lower portion of the sensor main body 200, and a smoke detection space 203 into which smoke flows is formed. A holder 204 is mounted on the sensor main body 200 side in the smoke detection space 203, and a light emitting unit 206 and a light receiving unit 208 are embedded in the holder 204 via openings 210 and 212, so that the holder 204 does not jump out into the smoke detection space 203. It has a structure with no directivity in the smoke inflow characteristics.
[0009]
The light emitting unit 206 emits light in the direction of the optical axis 214, and receives the scattered light caused by the light hitting the inflowing smoke by the light receiving unit 208 provided in the direction of the optical axis 216. For this reason, the optical axes 214 and 216 are arranged obliquely downward so that the light emitting unit 206 and the light receiving unit 208 do not face each other on a virtual vertical plane in the sensor, and the scattering angle θ of the optical axis intersection 218 is set to a predetermined angle. You have set. Note that the constituent angle δ has a relationship of θ = 180 ° −δ.
[0010]
On the other hand, the type of smoke caused by a fire varies depending on the burning material and the like, and the particle size of the smoke varies from relatively large to small. For this reason, one of the problems is to minimize the difference in sensitivity to smoke of various particle sizes.
[0011]
It is known that the scattering angle θ having a small sensitivity difference with respect to the smoke particle diameter is about 60 to 90 ° (90 to 120 ° for the constituent angle δ) (Patent Document 3).
[0012]
However, in the conventional structure shown in FIG. 13, when the scattering angle θ is increased to, for example, 60 ° in order to reduce the sensitivity difference with respect to the smoke particle diameter, the optical axis intersection point 218 ′ with respect to the installation surface of the holder 204 is obtained. The height of the detector must be increased accordingly, and the detector (smoke detector) cannot be thinned to avoid the effects of the reflected light from the ceiling surface. And the scattering angle θ cannot be set to an appropriate angle range such as 60 to 90 °.
[0013]
In this case, if the distance between the light emitting unit 206 and the light receiving unit 208 is narrowed so that the scattering angle is 60 to 90 °, it is possible to reduce the thickness. However, in this case, electric induction or direct leakage to the light receiving unit is performed. The problem of light effects occurs. That is, since the light emitting unit and the light receiving unit need to be arranged as far apart as possible, if the scattering angle is set to 60 ° to 90 ° without changing the height of the smoke detecting space, the smoke detecting unit cannot be made thin. .
[0014]
Therefore, the applicant of the present application has made the smoke detection section thinner and made it possible to freely set the scattering angle, there is no directionality in the flow of smoke into the smoke detection space, and furthermore, the light emitting section and the light receiving section are minimized. A photoelectric smoke detector that can be arranged at a distance has been proposed (Japanese Patent Application No. 2002-4221).
[0015]
As shown in FIG. 14, this scattered light type smoke detector has a light emitting portion 302 and a light receiving portion 303 in one smoke detecting portion main body 300 of a smoke detecting portion without projecting into a smoke detecting space, and a light emitting side opening 301. And the light receiving side opening 304 is opened and buried, and the optical axis from the light emitting unit 302 toward the smoke detection space and the optical axis of the scattered light scattered by the smoke particles in the smoke detection space toward the light receiving unit 303 are aligned in the horizontal direction. The light emitting unit 302 and the light receiving unit 303 are fixed so as to intersect at a predetermined angle with each other and at a predetermined angle in the vertical direction.
[0016]
As described above, the light emitting unit 302 and the light receiving unit 303 are embedded on the mounting surface side with respect to the smoke detection space, and a predetermined angle is set in both the horizontal direction and the vertical direction with the scattering angle of the optical axis set in the range of 60 to 90 °. With the arrangement, the height of the intersection of the optical axis with respect to the mounting surface is reduced, and the overall smoke detection space can be made even thinner.
[0017]
By setting the scattering angle of the light emitting portion and the light receiving portion due to the intersection of the optical axes in a range of about 60 to 90 °, the selectivity of smoke particles can be reduced. Furthermore, even if the height of the intersection of the optical axis with respect to the mounting surface is reduced, the light emitting unit and the light receiving unit do not come close to each other, so that there is no problem such as the influence of electric induction or leakage light received by the light receiving unit. .
[0018]
[Patent Document 1]
Japanese Utility Model Publication No. 10606 [Patent Document 2]
JP-A-60-10393 [Patent Document 3]
JP-A-7-72073 [Patent Document 4]
JP-A-63-103190 [Patent Document 5]
JP-A-1-259495
[Problems to be solved by the invention]
By the way, in the scattered light type smoke detector shown in FIG. 13, the opening shape of the light emitting part opening 220 and the light receiving part opening 221 is rectangular, and the interval between the light receiving part opening 220 and the light emitting part opening 221 is the center. The distance L5 is maintained uniformly in both the part 222 and the edge part 223.
[0020]
On the other hand, as shown in FIG. 14, the scattered light type smoke detector in which the light emitting unit 302 and the light receiving unit 303 are embedded on the mounting surface side with respect to the smoke detection space and arranged so as to have a predetermined angle in both the horizontal direction and the vertical direction. The distance between the light emitting side rectangular opening 301 and the light receiving side rectangular opening 304 is determined by the distance L4 between the center c of each opening and the distance L3 between the edge d of each opening. Will be different.
[0021]
For this reason, when dust, dust, or the like adheres to the dotted circle of the edge d near the light-receiving side rectangular opening 306 in the light-emitting side rectangular opening 305, the light from the light emitting unit 302 is applied to the dust, dust, or the like. There is a problem that stray light is increased due to the scattering, and stray light due to scattering is more likely to be incident on the light receiving unit than when dust of the same size or its dust adheres to the center part c.
[0022]
The present invention minimizes the effect on the light receiving unit when dust or lint adheres to the vicinity of the opening of the light emitting unit and the light receiving unit embedded on the mounting surface side with respect to the smoke detection space. It is an object to provide a scattered light smoke detector.
[0023]
[Means for Solving the Problems]
To achieve this object, the present invention is configured as follows. First, the present invention provides an opening portion without embedding the light emitting portion and the light receiving portion into the smoke detection space and burying the light emitting portion and the light receiving portion on the mounting surface side, and the optical axis from the light emitting portion toward the smoke detection space and the inside of the smoke detection space. A scattered light type in which the light emitting unit and the light receiving unit are arranged such that the optical axis of the scattered light scattered by the smoke particles and traveling toward the light receiving unit intersects at a predetermined angle in the horizontal direction and at a predetermined angle in the vertical direction. Targets smoke detectors.
[0024]
In the present invention, the scattered light type smoke detector having such a structure is characterized in that the opening shape on the side opposite to each opening of the light emitting unit and / or the light receiving unit is a part of a substantially elliptical shape. . Here, the opening shape that is a part of the substantially elliptical shape may be a shape in which a corner of a rectangular opening is cut out.
[0025]
In this way, by making the opening shape on the side where the light emitting unit and the light receiving unit face each other a part of a substantially elliptical shape, there is no edge portion that shortens the interval between the opening portions in the conventional rectangular opening, and the opening edge has dust. Even if dust or lint adheres, the distance to the light receiving unit side opening can be increased, so that the influence on the light receiving unit can be minimized, and a decrease in the S / N ratio can be prevented.
[0026]
The opening of the light emitting unit and the light receiving unit has a side wall standing upright along the opening, and a near light receiving side wall standing up along the light emitting side opening and a near light emitting side wall standing up along the light receiving side opening. The heights are approximately equal. Further, the side wall closer to the light receiving unit in the light emitting unit side wall is formed higher than the side wall farther from the light receiving unit.
[0027]
By forming the side wall closer to the light receiving portion of the light emitting portion side higher than the opposite side wall, dust and the like adhere to the lower side wall farther from the light receiving portion to generate scattered light. However, the scattered light hits the open upper side wall and is blocked, thereby minimizing the influence on the light receiving section and preventing a decrease in the S / N ratio.
[0028]
Further, in the scattered light smoke sensor of the present invention, as the opening of the light emitting portion, an opening concave portion is formed following the cylindrical hole for accommodating the light emitting portion. An arc-shaped light shielding portion is formed in which the near side is raised and the far side is lowered.
[0029]
By providing a light-shielding portion above the opening of the cylindrical hole from which light from the light emitting portion is emitted, light that directly hits the ceiling surface of the smoke detection space is reduced, and the smoke detection portion is made thinner, and consequently The sensor can be made thinner. Furthermore, by forming a chord-shaped light-shielding portion on the upper side of the opening of the cylindrical hole from which light from the light-emitting portion is emitted, a side closer to the light-receiving portion and a side farther down are formed, so that dust and the like are formed on the lower side of the light-shielding portion. Even if scattered light is generated due to adherence, the scattered light is generated at a low position, so that the scattered light hits the side wall of the opening close to the light receiving unit and is blocked, thereby minimizing the influence on the light receiving unit and reducing the S / N ratio. Can be prevented from decreasing.
[0030]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a sectional view showing an embodiment of a scattered light type smoke detector according to the present invention. In FIG. 1, the scattered light smoke detector includes a detector main body 1 and a cover 2. The detector main body 1 is composed of a smoke detector cover 6 attached to the lower part of the smoke detector main body 5 and a terminal board 13 attached to the upper part of the smoke detector main body 5.
[0031]
A smoke detection space 4 is formed in a smoke detection unit cover 6 arranged below the smoke detection unit main body 5. A labyrinth 14 is formed around the smoke detection space 4 integrally with the smoke detection section cover 6 to create a path through which smoke from the outside can easily flow in, and at the same time, block the incidence of light from the outside. A smoke inlet 3 is opened at a portion of the cover 2 located around the labyrinth 14.
[0032]
The smoke detection section main body 5 has a circuit board 12 disposed on the upper side on the back side, and a light emitting section 7 and a light receiving section 8 are provided on the smoke detection space 4 side, and respective lead wires are connected to the circuit board 12, Light emission driving and light receiving processing are performed. The light emitting section 7 irradiates light to the smoke detection space 4 through the light emission side opening 9 and scatters light generated when the smoke collides with the smoke particles when the smoke flows into the smoke detection space 4, and outputs the scattered light to the light reception side opening. The light enters the light receiving unit 8 through the reference numeral 10.
[0033]
Here, in the present invention, the optical axis from the light emitting unit 7 toward the smoke detection space 4 and the optical axis of the scattered light scattered by the smoke particles in the smoke detection space toward the light receiving unit 8 are predetermined in the horizontal direction. The light emitting unit 7 and the light receiving unit 8 are arranged in the smoke detection unit main body 5 so as to intersect at an angle α of the above and at a predetermined angle β in the vertical direction.
[0034]
FIG. 2 is an exploded view of the scattered light type smoke detector of FIG. In FIG. 2, the detector main body 1 has a smoke detector main body 5 attached to the terminal board 13 from below, and further has a smoke detector cover 6 attached to the smoke detector main body 5 from below. The assembled sensor main body 1 is housed in the cover 2, and an assembled state as shown in FIG. 1 can be obtained.
[0035]
FIG. 3 is a perspective view of the smoke detection section main body 5 according to the present invention as viewed from the smoke detection space 4 side. A light-emitting side opening 9 and a light-receiving side opening 10 are formed on the surface of the smoke detection section main body 5 on the smoke detection space side. The cross section of the light emitting side opening 9 and the light receiving side opening 10 in the smoke detector main body 5 is as shown in FIG.
[0036]
FIG. 4 is a cross-sectional view of a smoke detection section assembly in which the smoke detection section main body 5 and the smoke detection section cover 6 in the present invention are combined, and is shown upside down with respect to FIGS. In FIG. 4, the light emitting unit 7 and the light receiving unit 8 with respect to the smoke detecting unit main body 5 include a light emitting optical axis 25 from the light emitting unit 7 toward the smoke detecting space 4 and a light receiving unit scattered by smoke particles in the smoke detecting space 4. The light receiving optical axis 26 of the scattered light toward 8 intersects at a predetermined angle α in the horizontal direction and intersects at an angle β in the vertical direction, as will be described later.
[0037]
Further, a cylindrical hole 15 is formed following the storage portion of the light emitting section 7, and an opening concave portion 16 is formed following the cylindrical hole 15, and the cylindrical hole 15 opens to the inner wall surface of the opening concave portion 16. Similarly, a light receiving hole 18 and an opening recess 19 are formed on the light receiving section 8 side, and the light receiving hole 18 is opened in the opening recess 19.
[0038]
FIG. 5A schematically shows, in a three-dimensional coordinate space, an optical positional relationship corresponding to the installation positions of the light emitting unit 7 and the light receiving unit 8 provided in the smoke detection unit main body 5 of FIG.
[0039]
In FIG. 5 (A), the light-emitting optical axis 25 from the light-emitting point P by the light-emitting unit 7 is indicated by a vector, and the light-receiving optical axis 26 on which the scattered light from the optical axis intersection O enters is a vector with respect to the light-receiving point Q of the light receiving unit 9 Indicated by.
[0040]
The triangle connecting the light emitting point P, the optical axis intersection O and the light receiving point Q is a virtual optical surface for scattered light type smoke detection in the smoke detector structure of the present invention, and the surface forming the triangle POQ is an xy plane. Are arranged at a certain angle with respect to each of a horizontal plane and a vertical plane which is a zx plane.
[0041]
For the sake of simplicity, the projection of the light emitting point P on the x axis is arranged so as to be the projection point A. Therefore, the vertical inclination angle φ of the light emitting optical axis 14 is equal to the angle with respect to the x axis in this case. Become.
[0042]
Here, when the light emitting optical axis 25 and the light receiving optical axis 26 are viewed from a horizontal plane that is an xy plane, the projection point A corresponds to the light emitting point P and the projection point B corresponds to the light receiving point Q as shown in FIG. . That is, the light emitting optical axis 25 and the light receiving optical axis 26 intersect at a predetermined angle α in the horizontal direction. On the other hand, when the light emitting optical axis 14 and the light receiving optical axis 15 are projected on the surface ABQP, the light emitting optical axis and the light receiving optical axis intersect at a predetermined angle β in the vertical direction.
[0043]
For example, if the vertical inclination angle φ is set to 30 ° and the apparent constituent angle α in the horizontal plane is 120 °, the constituent angle δ is 97 °. If the apparent constituent angle α in the horizontal plane is set to α = 120 ° and the inclination angle φ is set to φ = 9.8 °, the constituent angle δ becomes δ = 117 °.
[0044]
In summary, the actual angle δ is 117 ° and 97 °, while the angle φ = 9.8 ° and 30 ° when the apparent angle α = 120 ° is kept constant. In the case where the position of P and the light receiving point Q in the horizontal direction is not changed, if the inclination angle φ in the vertical direction is increased, a relationship in which the actual constituent angle δ is reduced is obtained. Of course, if the inclination angle φ in the vertical direction is reduced, the height of the optical axis intersection O is reduced, so that the thickness is further reduced.
[0045]
Based on the three-dimensional relationship between the optical axes from light emission to light reception as shown in FIG. 5, in the embodiment of the present invention, the constituent angle δ between the light emission optical axis 25 and the light reception optical axis 26 is approximately 110 °. Of course, the scattering angle θ corresponding to this constituent angle δ = 110 ° is θ = 180 ° −δ = 70 °.
[0046]
As described above, according to the present invention, with the optical axis 25 of the light emitting unit 7 and the optical axis 26 of the light receiving unit 8 set to the constituent angle δ = 110 °, the apparent constituent angle α in the horizontal plane and the inclination in the vertical plane By embedding and arranging in the smoke detection unit main body 5 so as to have an angle φ, the amount of projection of the optical axis intersection point for smoke is suppressed to a low level even if optimum angle arrangement with little effect on sensitivity to the size of smoke particles is performed. Therefore, a thin structure of the sensor can be realized.
[0047]
FIG. 6 is a plan view of the light-emitting side opening 9 and the light-receiving side opening 10 of the smoke detection section main body 5 according to the present invention as viewed from the smoke detection space side. I have.
[0048]
In FIG. 6, the light-emitting side opening 9 and the light-receiving side opening 10 form elliptical openings 20 and 21 on the side facing each other, where the opening shape is a part of the elliptical shape in a region surrounded by oblique lines in FIG. I have. The minimum interval between the elliptical openings 20 and 21 is L1 in the drawing.
[0049]
7 and 8 are explanatory views showing the conventional opening and the opening of the present invention in comparison. FIG. 7A shows a conventional opening, which is the same as that shown in FIG. On the other hand, FIG. 7B shows an opening of the present invention, which corresponds to FIG.
[0050]
FIG. 8C shows another embodiment of the opening of the present invention, in which the light emitting side openings which are not sandwiched by the light emitting direction center line 25a of the light emitting portion and the light receiving direction center 26a of the light receiving portion, that is, are not opposed to each other. FIG. 7B differs from FIG. 7B in that the shape of the portion 9 and the light-receiving-side opening 10 is a part of a rectangle. However, the position of the two openings closest to each other is on the side where the light-emitting side opening and the light-receiving side opening face each other, and is the minimum distance L1.
[0051]
FIG. 8D shows another embodiment of the opening of the present invention, in which the light emitting side opening 9 and the light receiving side opening sandwiched between the light emitting direction center line 25a of the light emitting portion and the light receiving direction center 26a of the light receiving portion. On the side where the parts 10 face each other, the opening has a shape in which a part of a rectangular shape is cut out. That is, the directions of the notched sides 29a and 29b of the light emitting side opening and the light receiving side opening intersect with the light emitting direction center line 25a or the light receiving direction center line 26a at intersection angles φ1 and φ2 of less than 90 °, respectively. The light emitting side opening 9 and the light receiving side opening 10 have a minimum distance of L1.
[0052]
Here, in the conventional opening of FIG. 7A, that is, in the region between the light emitting direction center line 25a of the light emitting unit and the light receiving direction center line 26a of the light receiving unit, the light emitting side opening 301 and the light receiving side When the positions of the light receiving unit and the light emitting unit in the sensor are fixed, the distance between the edge a of the rectangular opening 305 and the edge b of the rectangular opening 306 is the above-mentioned distance. The distance L2 is shorter than L1.
[0053]
When the distance L2 between the edges a and b of the rectangular openings 305 and 306 is short, when dust or the like adheres to the dotted circle portion of the light emitting side edge a, the light hit by the dust is scattered. The stray light is likely to enter the light receiving unit from the rectangular opening 306 on the light receiving side.
[0054]
In order to reduce stray light due to the adhesion of dust near the edge a of the light emitting side opening, the distance L2 needs to be increased, and therefore, the distance between the light emitting part and the light receiving part must be increased. However, if the distance between the light-emitting portion and the light-receiving portion is increased, the effect of stray light due to the adhesion of dust can be reduced, but there is a problem that the absolute light amount decreases.
[0055]
Therefore, according to the present invention, as shown in FIGS. 7B, 8C, and 8D, the light emitting side opening is not changed without changing the arrangement positions of the light emitting portion and the light receiving portion, that is, without decreasing the absolute light amount. In order to reduce only the influence of dust or the like attached to the portion 9, the side opposite to the light-emitting side opening 9 and the light-receiving side opening 10 is formed with an oval opening 20, 21 or a notch opening 22 having a shape in which a part of a rectangle is cut out. , 23.
[0056]
This eliminates the edges a and b of the conventional rectangular openings 305 and 306 in FIG. 7A that shorten the distance between the openings, thereby eliminating the cases of the elliptical openings 20 and 21 and the cutout openings 22 and 23. L1 is maintained as the closest distance. The distance L1 between the openings 20, 21, 22, and 23 is smaller than the distance L2 between the rectangular openings 305 and 306 in FIG. 7A without changing the arrangement positions of the light emitting unit and the light receiving unit. Can be increased, thereby reducing the influence of stray light due to dust or the like adhering to the edge of the light-emitting side elliptical opening 20 and improving the S / N ratio of the sensor.
[0057]
FIG. 9 is a graph showing the relative output of the light receiving unit to the adhesion of dust between the conventional opening and the opening of the present invention. In FIG. 9, the relative output of the conventional rectangular aperture characteristic 40 starts to appear when the size of dust is around 0.5 mm, and the relative output sharply increases when the size exceeds 0.7 mm.
[0058]
On the other hand, in the elliptical opening characteristic or the notch opening characteristic 41 of the present invention, the relative output appears when the dust size is around 1 mm, and when the dust exceeds 1.2 mm, the relative output sharply increases. From the characteristics of the relative output with respect to the size of the dust, the effect of improving the S / N ratio against the adhesion of the dust by the opening of the light emitting unit and the light receiving unit according to the present invention having the elliptical openings is sufficiently obtained. Can be confirmed.
[0059]
In the description of the embodiments, the term “ellipse” is used. However, the present invention must strictly satisfy the definition of a so-called ellipse, that is, “the whole point where the sum of the distances between two points becomes constant”. The opening shape is not limited to this, and may be an opening shape in which a part or the whole of the rectangular opening is curved, and there is no problem as long as the opening has a substantially elliptical shape.
[0060]
FIG. 10 is an explanatory view of the light shielding portion 30 provided above the cylindrical hole opening of the light emitting side opening in the present invention. FIG. 10A is a perspective view of the smoke detection section main body 5, and shows the light axis direction of the light emission side opening 9 as viewed from the front. FIG. 10B is an enlarged view of a vertical cross section of the cylindrical hole opening when viewed from the direction of arrow XX when cut at the dotted line position of the light emitting side opening 9 in FIG.
[0061]
10B, the cross section of the opening has a U-shaped groove shape, and the cylindrical hole 15 for emitting light from the light emitting unit 7 shown in FIG. 4 is opened.
[0062]
Further, in the present invention, the light shielding portion 24 is formed above the opening of the cylindrical hole 15. The light-shielding portion 24 has an arc-shaped light-shielding shape in which an inner end 24a closer to the light-receiving portion rises and an outer end 24b farther away lowers, and the inclination γ of the light-shielding portion 24 is γ = 5 °. Set to about.
[0063]
Further, in accordance with the arc-shaped light shielding portion 24 having an inclination of the angle γ, the near light receiving side wall 9a closer to the light receiving portion of the opening concave portion 16 is higher and the far light receiving side wall 9b farther from the light receiving portion is lower. I have.
[0064]
Here, the side wall structure raised along the openings of the light emitting side opening 9 and the light receiving side opening 10 will be described with reference to FIG. The light emitting side opening 9 has a near light receiving side wall 9a close to the light receiving portion along the opening and a far light receiving portion side wall 9b far from the light receiving portion. The light-receiving-portion-side opening 10 has a near-light-emitting-side sidewall 10a near the light-emitting portion and a far-light-emitting-side sidewall 10b far from the light-emitting portion along the opening.
[0065]
In the present invention, as shown in FIG. 10 (B), the near / far light receiving side wall 9a of the light emitting side opening 9 is formed to be higher than the far light receiving side wall 9b. For this reason, even if dust adheres to the upper edge portion of the far light receiving side wall 9b, the dust can enter the light receiving area shown in FIG. Is reduced. Therefore, compared to the case where the near light receiving side wall 9a and the far light receiving side wall 9b of the light emitting side opening 9 have the same protrusion amount, the effect of dust attached to the upper edge of the far light receiving side wall 9b is reduced. I do.
[0066]
Further, in the present invention, the protruding heights of the near-light-receiving side wall 9a and the near-light-emitting side wall 10a from the smoke detection unit main body are formed to be substantially equal. In this case, as shown in FIG. 11 (A), the light from the light emitting section 7 forms a monitoring area 11a by the light shielding section 24 and the near light receiving side wall 9a and the far light receiving side wall 9b of the light emitting side opening 9. In this case, in particular, the near-light-emitting side wall 10a and the near-light-receiving-side wall 9a have substantially the same height so that the near-light-emitting side wall 10a or the far-light-emitting side wall 10b of the light-receiving-side opening 10 does not enter the monitoring area 11a. It is desirable that
[0067]
Further, as shown in FIG. 11 (B), in order to prevent the near light receiving side wall 9a and the far light receiving side wall 9b of the light emitting side opening 9 from entering the light receiving area 1lb where the light receiving unit 8 receives light. In particular, the protruding heights of the near-light-emitting side wall 10a and the near-light-receiving side wall 9a of the light-receiving opening 10 need to be substantially equal. Since the far side wall 9b is lower than the near side wall 9a, it does not enter the light receiving region 1lb.
[0068]
As described above, in the present invention, the light from the light emitting unit is shielded by forming the arc-shaped light shielding unit 24 above the cylindrical hole 15 through which the light from the light emitting unit is emitted in the light emitting side opening 9. The scattered light, which is blocked by the section 24 and directly hits the ceiling side of the smoke detection space 4, prevents the S / N ratio of the detector from being deteriorated.
[0069]
Also, the far light receiving side wall 9b of the light emitting side opening 9 to which dust easily adheres is located at a lower position lower than the near light receiving side wall 9a, but as shown in FIG. By arranging the outer end 24b with the inclination of the predetermined angle γ that becomes lower at the outer end 24b, it is possible to prevent the light from being irradiated in the labyrinth direction beyond the lower side wall on the far light receiving side.
[0070]
In the above embodiment, for simplicity of description, the case where the light emitting unit and the light receiving unit are embedded such that the light emitting optical axis and the light receiving optical axis are at the same angle in the vertical direction is taken as an example. The light emitting unit and the light receiving unit may be embedded such that the optical axis and the light receiving optical axis are at different angles in the vertical direction.
[0071]
In addition, the present invention is not limited to the above embodiments, and includes appropriate modifications without impairing the objects and advantages thereof. Furthermore, there is no limitation by the numerical values shown in the above embodiment.
[0072]
【The invention's effect】
As described above, according to the present invention, the opening shape on the side facing the light-emitting portion and the light-receiving portion is made a part of a substantially elliptical shape, thereby reducing the interval between the opening portions in the conventional rectangular opening. Even if dust or thread dust adheres to the edge of the opening, the elliptical opening can increase the distance from the light-receiving side opening, so that stray light generated by the attachment of dust or the like enters the light-receiving part. Can be prevented, and the S / N ratio of the sensor can be improved.
[0073]
In addition, the opening of the light emitting unit and the light receiving unit, the side wall is erected along the opening, the height of the light receiving side wall and the height of the light emitting side wall are substantially equal, and the side wall of the light emitting unit side wall closer to the light receiving unit is By forming it higher than the side wall on the far side of the light receiving section, even if dust and the like adhere to the lower side wall on the far side of the light receiving section and generate scattered light, the scattered light hits the open side higher side wall. It is possible to minimize the influence on the light receiving unit due to being blocked, and to prevent a decrease in the S / N ratio.
[0074]
In addition, as an opening from the light emitting portion, an opening concave portion is formed following the cylindrical hole that emits light from the light emitting portion, and an upper portion near the light receiving portion rises above the opening of the cylindrical hole with respect to the opening concave portion, and a far side decreases and has an arc shape. By forming the light-shielding portion, light directly hitting the ceiling surface of the smoke detection space can be reduced, and the smoke detection portion can be made thinner, and as a result, the sensor can be made thinner.
[0075]
In addition, dust is attached to the light-shielding end far from the light-receiving part by raising the near side and lowering the far-side of the cylindrical light-shielding part above the cylindrical hole from which the light from the light-emitting part exits. Even if scattered light is generated, this scattered light is generated at a low position and is blocked by hitting the side wall of the opening concave side on the opposite side near the light receiving unit, minimizing the influence on the light receiving unit due to adhesion of dust etc. And improve the S / N ratio of the sensor.
[Brief description of the drawings]
1 is a sectional view showing an embodiment of a scattered light type smoke detector according to the present invention; FIG. 2 is an exploded view of the scattered light type smoke detector of FIG. 1; FIG. FIG. 4 is a cross-sectional view of a smoke detector assembly in which a smoke detector main body and a smoke detector cover are combined according to the present invention. FIG. 5 is a positional relationship between a light emitting unit and a light receiving unit according to the present invention. FIG. 6 is a plan view of the main part of the smoke detection section of the present invention viewed from the smoke detection space side. FIG. 7 is an explanatory view showing a conventional opening and an opening of the present invention in comparison. FIG. 9 is an explanatory view of another embodiment of the opening of the present invention. FIG. 9 is a graph showing the relative output of the light receiving unit to the adhesion of dust between the conventional opening and the opening of the present invention. FIG. 11 is an explanatory view of a light shielding portion provided above a cylindrical hole opening of a light emitting side opening in the present invention. FIG. 12 is an explanatory view of a monitoring area and a light receiving area in a space. FIG. 12 is an explanatory view of a conventional sensor structure. FIG. 13 is an explanatory view of a conventional structure in which a light emitting unit, a light receiving unit, and the like are not protruded into a smoke detection space. Explanatory drawing of a light-emitting part and a light-receiving part in a scattered light sensor proposed by humans with rectangular openings.
1: Sensor body 2: Cover 3: Smoke inlet 4: Smoke detection space 5: Smoke detection unit main body 6: Smoke detection unit cover 7: Light emitting unit 8: Light receiving unit 9: Light emitting side opening 9a: Near light receiving side side wall 9b: far light receiving side wall 10: light receiving side opening 10a: near light emitting side wall 10b: far light emitting side wall 11a: monitoring area 11b: light receiving area 12: circuit board 13: terminal board 14: labyrinth 15: cylindrical hole 18: light receiving Holes 20, 21: Elliptical apertures 22, 23: Notch aperture 24: Light shield 25, 26: Optical axis 25a: Light emission direction center line 26a: Light reception direction center line 30: Light shield

Claims (4)

The light emitting part and the light receiving part are provided with an opening without being protruded into the smoke detection space and buried on the mounting surface side, and the optical axis from the light emitting part toward the smoke detection space and the smoke particles in the smoke detection space The scattered light in which the light emitting unit and the light receiving unit are arranged so that the optical axis of the scattered light scattered by the light receiving unit crosses at a predetermined angle in the horizontal direction and crosses at a predetermined angle in the vertical direction. In the smoke detector,
The scattered light type, wherein the opening shape on the side opposite to each opening of the light emitting unit and / or the light receiving unit is a part of a substantially elliptical shape, or the opening shape is a shape obtained by cutting out a corner portion of a rectangular opening. Smoke detectors. 2. The scattered light type smoke detector according to claim 1, wherein the opening of the light emitting unit and the light receiving unit has a side wall standing up along the opening, and the near light receiving side wall standing up along the light emitting side opening and receiving light. A scattered light type smoke detector characterized in that the height of the near light emitting side wall rising along the side opening is substantially equal. 3. The scattered light type smoke detector according to claim 1, wherein the opening of the light emitting unit and the light receiving unit has a side wall standing upright along the opening, and the heights of the light receiving side wall and the light emitting side wall are substantially equal. A scattered light type smoke detector, wherein a side wall closer to the light receiving unit in the side wall on the light emitting unit is formed higher than a side wall farther from the light receiving unit. 4. The scattered light smoke sensor according to claim 1, wherein the opening of the light-emitting unit forms an opening recess following the cylindrical hole that houses the light-emitting unit, and the cylinder with respect to the opening recess. 5. A scattered light type smoke detector characterized in that an arc-shaped light shielding portion is formed at the upper part of the opening of the hole, with the side close to the light receiving part rising and the side far from the light receiving part falling.

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