JP2016115061A - Photoelectric smoke detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric smoke detector capable of suppressing erroneous detection due to stray light such as scattering light.SOLUTION: A photoelectric smoke detector includes: a housing 21 having a plurality of labyrinth form wall parts 23 arranged side by side via a gap which allows a smoke to inflow from the outside and blocks light from the outside; a light emission part 25 for emitting light to the interior of the housing 21; a light receiving part 26 for detecting scattering light due to the smoke that inflows to the interior; and a reflection part 27 for reflecting the light emitted from the light emission part 25. The reflection part 27 includes: a first reflection surface 27a inclined to an optical axis A1 of the light emission part 25; and a second reflection surface 27b for receiving reflection light reflected by the first reflection surface 27a. The side of the light emission part 25 in the second reflection surface 27b is inclined to the side of the optical axis A1, and an end part of the side of the light emission part 25 in the second reflection surface 27a is equal to the distance up to the light emission part 25 or placed in a near distance when compared to the end part of the side of the light emission part 25 in the first reflection surface 27a.SELECTED DRAWING: Figure 2

Description

  The present invention includes a housing having a plurality of labyrinth-like wall portions juxtaposed via a gap so as to allow smoke from the outside to flow in and block light from the outside, and to irradiate the inside of the housing with light A light-emitting unit; a light-receiving unit that detects scattered light due to smoke that has flowed into the housing; and a reflective unit that is disposed to face the light-emitting unit and reflects light emitted from the light-emitting unit. The present invention relates to a photoelectric smoke detector.

  The photoelectric smoke detector includes, for example, a light diffusion sensor unit having a light emitting unit and a light receiving unit, and the light receiving unit detects light from the light emitting unit scattered by the smoke flowing into the sensor unit. It senses the presence of smoke.

  For example, in Patent Document 1, as a photoelectric smoke detector, there is a reflector that reflects light emitted from a light emitting unit toward a smoke detection region including an intersection between the light emitting unit and the light receiving unit. A configuration in which the light emitting unit is disposed to face the light emitting unit has been known.

  In the photoelectric smoke detector described in Patent Document 1, each axial center of the light emitting unit and the light receiving unit can be configured to form an angle of less than 100 °, so that the light receiving unit is a light flux of light emitted from the light emitting unit. Therefore, it is possible to reduce erroneous detection due to the light receiving unit directly detecting the light emitted from the light emitting unit. Further, in this photoelectric smoke detector, the reflecting plate arranged opposite to the light emitting unit reflects the light emitted from the light emitting unit toward the smoke detection region, and thus is generated by the smoke entering the smoke detection region. The brightness or amount of scattered light was increased, and the decrease in sensing ability could be suppressed.

JP 2010-20470 A

  In general, a photoelectric smoke detector installed on a wall surface is in an environment in which foreign matters such as dust easily enter from above. If dust or the like enters the inside of the sensor unit, scattered light is generated even when smoke is absent, and there is a risk of erroneous detection.

  Accordingly, an object of the present invention is to provide a photoelectric smoke detector capable of suppressing erroneous detection due to stray light such as scattered light.

  In order to achieve the above object, a photoelectric smoke detector according to the present invention includes a plurality of labyrinth-like wall portions juxtaposed through a gap so as to allow smoke from the outside to flow in and block light from the outside. A housing provided with, a light emitting part for irradiating light inside the housing, a light receiving part for detecting scattered light due to smoke flowing into the housing, and a light emitting part disposed opposite to the light emitting part. A photoelectric smoke detector having a reflecting portion for reflecting the irradiated light, wherein the first characteristic configuration is that the reflecting portion is a first reflecting surface inclined with respect to the optical axis of the light emitting portion. And a second reflecting surface that receives the reflected light reflected by the first reflecting surface, and the light emitting portion side of the second reflecting surface is inclined toward the optical axis, An end of the light emitting portion side on the reflective surface is the first reflective surface. Compared with the end of the side of definitive light emitting unit or the distance to the light emitting portion is equal, in a point located at a short distance.

According to this configuration, in the reflecting portion, the first reflecting surface reflects the light from the light emitting portion, and the reflected light can be received by the second reflecting surface inclined toward the optical axis. The reflected light can be reflected to the side of the light receiving unit located on the optical axis side.
Further, the end on the light emitting unit side of the second reflecting surface is configured so that the distance to the light emitting unit is equal to or close to the end of the first reflecting surface on the light emitting unit side. is there. For this reason, it is possible to make it difficult to reflect the reflected light of the first reflecting surface to the facing side of the light receiving unit.

  Therefore, since the reflecting part can reflect most of the reflected light of the first reflecting surface toward the light receiving part via the second reflecting surface, the reflected light is reflected to the facing side of the light receiving part and In comparison, the level of stray light can be significantly reduced. Therefore, the photoelectric smoke detector of the present invention can suppress erroneous detection due to stray light.

  The second characteristic configuration of the photoelectric smoke detector according to the present invention is that an extension line on the light emitting portion side of the second reflecting surface is directed to the light emitting portion.

  According to this configuration, by arranging the second reflecting surface to be inclined as described above, the reflected light of the second reflecting surface can be favorably reflected toward the light receiving unit.

  According to a third characteristic configuration of the photoelectric smoke detector according to the present invention, the light receiving unit is disposed at a position for receiving the reflected light reflected by the second reflecting surface, and is disposed between the light receiving unit and the second reflecting surface. Is provided with a light shielding wall for shielding a part of the reflected light.

By providing a light shielding wall as in this configuration, a part of the reflected light of the second reflecting surface, for example, the peripheral part of the light flux of the reflected light is shielded, and the reflected light that is not shielded is incident on the light receiving unit. Can do. As a result, the level of stray light caused by the peripheral portion of the reflected light beam can be significantly reduced.
Therefore, with the photoelectric smoke detector of this configuration, it is possible to further suppress erroneous detection due to stray light.

1 is an external view of a fire alarm equipped with a photoelectric smoke detector according to the present invention. It is a top view schematic diagram of the smoke detection part provided in the photoelectric smoke detector. It is sectional drawing of a smoke detection part. It is a sectional exploded view of a smoke sensing part. It is the disassembled perspective view which looked at the smoke detection part from the back surface.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIGS. 1-5, in this embodiment, the fire alarm produced on the assumption that the photoelectric smoke detector of the present invention is attached to the most common indoor vertical wall surface and used in a wall-mounted manner. The case where it applies to the smoke detection part 2 of the container 1 is demonstrated.

  As shown in FIGS. 1 (a) and 1 (b), a fire alarm 1 includes a smoke detection unit 2 that detects smoke, an alarm speaker unit 3 that notifies the detection of smoke by an alarm sound such as a voice or a buzzer, And an alarm lamp 4 for notifying the detection by lighting or blinking of light by an LED or the like.

  When the smoke detector 2 detects smoke, the fire alarm 1 determines, for example, whether the smoke concentration is higher or lower than a preset threshold, and if the smoke concentration exceeds the threshold, it is determined as a fire. Then, the alarm speaker 3 and the alarm lamp 4 are activated. The activated alarm speaker 3 and alarm lamp 4 can be stopped by operating the alarm stop button 5. On the back of the fire alarm 1, there are provided an attachment part (not shown) for fixing the fire alarm 1 to a wall material, a battery storage part (not shown) for storing a battery for driving the fire alarm 1, etc. is there.

  The smoke detection unit 2 includes a cylindrical housing 21. The housing 21 is disposed on the substrate 6 accommodated in the housing 21 together with a power connector (not shown), the alarm speaker unit 3 and the like (FIG. 5).

(housing)
As shown in FIG. 2, the housing 21 includes a plurality of labyrinth-like wall portions 23 that are juxtaposed via a gap so that smoke from the outside flows in and light from the outside is blocked.

  A smoke detection chamber 22 for detecting smoke is provided inside the housing 21. The wall portion 23 has, for example, a bowl-like shape and is disposed so as to surround the smoke detection chamber 22. A large number of juxtaposed wall portions 23 are juxtaposed through a gap portion such as a crank shape to block external light from entering the smoke sensing chamber 22 and to allow inflow of smoke from the outside. A labyrinth structure is formed. Further, an insect screen (not shown) may be provided outside the wall portion 23 to prevent erroneous detection due to insects entering the smoke sensing chamber 22.

  Inside the housing 21, there are provided a light emitting unit 25 that irradiates the smoke sensing chamber 22 with light such as near infrared rays, and a light receiving unit 26 that detects scattered light caused by smoke flowing into the housing 21. The light emitting unit 25 includes a light emitting element 25D such as a light emitting diode as a light source, and a condensing lens 25L disposed in front of the light emitting element 25D inside the light emitting unit accommodating unit 25a. The light receiving unit 26 includes a light receiving element 26D such as a photodiode and a condensing lens 26L disposed in front of the light receiving element 26D inside the light receiving unit accommodating unit 26a.

  Further, a reflection unit 27 that reflects light emitted from the light emitting unit 25 is disposed to face the light emitting unit 25. The reflection part 27 has a reflection surface in which a rectangular resin surface is made into a mirror surface having a high reflectivity by polishing, for example, with a No. 2000 compound.

  The housing 21 is disposed on the substrate 6. As shown in FIG. 5, a pair of claw portions 21 </ b> C are provided in the diameter direction on the back surface of the outer periphery of the housing 21, and can be fixed to the base 6 by the claw portions 21 </ b> C.

  When the housing 21 is disposed on the substrate 6, the protruding peripheral portion 21 </ b> D that protrudes on the outer periphery on the back surface side of the housing 21 comes into contact with the substrate 6. Projecting on the back side of the housing 21. The contact region 29 can be formed so as to protrude at a position corresponding to a portion where at least one of the light emitting unit 25 and the light receiving unit 26 is disposed. In the present embodiment, the case where the contact region 29a and the contact region 29b formed corresponding to the light emitting unit 25 and the light receiving unit 26 are provided will be described, but the present invention is not limited to this.

  The part can be provided with a connection pin 61 that normally connects the substrate 6 and the housing 21 and can be energized. The contact regions 29a and 29b can be formed in a substantially rectangular shape when viewed from above, but are not limited to this shape.

  The contact regions 29 a and 29 b respectively have concave portions 29 A (29 Aa and 29 Ab) that are formed in a concave shape so as to be separated from the substrate 6.

  The recessed portion 29 </ b> A includes an installation portion 29 </ b> B of a connection pin 61 that connects the substrate 6 and the housing 21. In this configuration, the setting area of the recessed portion 29A (29Aa, 29Ab) can be at least around the installation portion 29B (29Ba, 29Bb) of the connection pin 61.

(Light emitting part)
As shown in FIG. 2, the light emitting unit 25 may be arranged so that the optical axis A1 of the light emitting element 25D and the condensing lens 25L is substantially horizontal, for example. A light shielding portion 25A is formed on the outer side of the condenser lens 25L. The light-shielding part 25A is opposite to the light-receiving part 26 from the width of the light-receiving part-side light-shielding part 25A1 located on the light-receiving part 26 side (the width in the direction perpendicular to the optical axis A1 in FIG. 2). The width of 25A2 is formed larger. As described above, the light shielding part 25A is formed asymmetrically in a top view, and the opposite side light shielding part 25A2 is formed to have a larger width, thereby making it difficult to leak light to the opposite side of the light receiving part 26.

  A part of the front surface of the light emitting unit 25 is covered with a light emitting unit cover member 25B (FIGS. 3 and 4). The light emitting unit cover member 25 </ b> B of the present embodiment is disposed integrally with the housing lid member 21 </ b> A that is the upper surface side of the housing 21. When the light emitting unit cover member 25B is mounted, the joint 25b between the light emitting unit cover member 25B and the light emitting unit accommodating unit 25a that accommodates the light emitting unit 25 is formed so as not to interfere with the optical axis A1 of the light emitting unit 25. is there. The lower end portion 25C of the light emitting unit cover member 25B is also formed so as not to interfere with the optical axis A1 of the light emitting unit 25. By forming the lower end portion 25C so as not to interfere with the optical axis A1 of the light emitting portion 25, the light emitted from the light emitting portion cover member 25B from the light emitting portion 25 to the smoke sensing chamber 22 is not blocked.

  The housing lid member 21A is integrally provided with a light emitting part pressing member 25E on the outer side of the light emitting part cover member 25B. The lower end portion 25F of the light emitting portion pressing member 25E is formed so as to be at a substantially intermediate position in the thickness direction of the light emitting portion 25. As described above, the lower end portion 25C of the light emitting portion cover member 25B and the lower end portion 25F of the light emitting portion pressing member 25E are formed to have different heights relative to the housing lid member 21A.

  The corner portion of the joint portion 25b of the light emitting portion cover member 25B of the light emitting portion 25 has a thin portion 25G formed to be thin. The thin portion 25G in the present embodiment is formed as a rectangular thin portion at the corner portion, but is not limited to such an aspect. In addition, the thickness of the thin portion 25G in the present embodiment is preferably set to about half the thickness of the light emitting portion cover member 25B, but is not limited thereto.

(Light receiving section)
As shown in FIG. 2, in the light receiving unit 26, the optical axis A <b> 2 of the light receiving element 26 </ b> D and the condenser lens 26 </ b> L intersects the optical axis A <b> 1 of the light emitting unit 25, for example, approximately 90 ° at the approximate center of the smoke sensing chamber 22. It is good to arrange like this. On the outer side of the condenser lens 26L, an optical trap portion 26A, which is a trapezoidal space in a top view, is formed. The light that has entered the light trap part 26A is reflected on the inner surface of the light trap part 26A, so that it is difficult for the light to enter the condenser lens 26L side, and scattered light that causes erroneous detection enters the light receiving part 26. Can be prevented in advance.

  A part of the front surface of the light receiving unit 26 is covered with a light receiving unit cover member 26B (FIGS. 3 and 4). The light receiving unit cover member 26 </ b> B of the present embodiment is disposed integrally with the housing lid member 21 </ b> A that is the upper surface side of the housing 21. When the light receiving portion cover member 26B is mounted, the joint 26b between the light receiving portion cover member 26B and the light receiving portion accommodating portion 26a for accommodating the light receiving portion 26 is formed so as not to interfere with the optical axis A2 of the light receiving portion 26. is there. The lower end portion 26C of the light receiving portion cover member 26B is also formed so as not to interfere with the optical axis A2 of the light receiving portion 26. By forming the lower end portion 26C so as not to interfere with the optical axis A2 of the light receiving portion 26, the light receiving portion cover member 26B does not block light incident on the light receiving portion 26 from the smoke sensing chamber 22.

  In the housing lid member 21A, a light receiving portion pressing member 26E is integrally disposed on the outer side of the light receiving portion cover member 26B. The lower end portion 26F of the light receiving portion pressing member 26E is formed at a substantially intermediate position in the thickness direction of the light receiving portion 26. As described above, the lower end portion 26C of the light receiving portion cover member 26B and the lower end portion 26F of the light receiving portion pressing member 26E are formed to have different heights with respect to the housing lid member 21A.

(Reflection part)
As shown in FIG. 2, the reflecting portion 27 is disposed on the optical axis A <b> 1 of the light emitting portion 25. The smoke detection unit 2 detects the presence of smoke by detecting scattered light generated when smoke enters the smoke detection area 22A that spreads around the intersection of the optical axis A1 and the optical axis A2.

  The reflection part 27 may be provided separately from the labyrinth-like wall part 23 or may be formed as a part of the wall part 23. In this embodiment, the case where it forms as a part of the said wall part 23 is demonstrated. Therefore, the reflecting portion 27 of the present embodiment has a shape integrally formed with the bowl-shaped wall portion 23.

  The reflection unit 27 includes a first reflection surface 27a that is inclined with respect to the optical axis A1 of the light emitting unit 25, and a second reflection surface 27b that receives the reflected light reflected by the first reflection surface 27a. The light emitting unit 25 side of the second reflecting surface 27b is inclined toward the optical axis A1 with respect to the optical axis A1. Further, the end of the second reflecting surface 27b on the light emitting unit 25 side has the same distance to the light emitting unit 25 as compared with the end of the first reflecting surface 27a on the light emitting unit 25 side, or is located at a short distance. It is comprised so that it may do. In the present embodiment, a case will be described in which the end portion on the light emitting portion 25 side in the second reflecting surface 27b is positioned closer to the end portion on the light emitting portion 25 side in the first reflecting surface 27a.

  In general, stray light is generated by reflection or scattering of light inside the apparatus, reflection or scattering of light due to dirt (such as oil stains), scratches, or deterioration of the optical system. That is, the scattered light may be generated even when smoke is absent due to dirt that has entered the inside of the apparatus or dirt that is attached to oil components contained in kitchen smoke or the like.

  In the reflection part 27 in the present invention, the light from the light emitting part 25 is reflected by the first reflection surface 27a, and the reflected light can be received by the second reflection surface 27b inclined to the optical axis A1 side. The reflected light from the reflecting surface 27b can be reflected toward the light receiving unit 26 located on the optical axis A1 side.

  Further, the end of the second reflecting surface 27b on the light emitting unit 25 side has the same distance to the light emitting unit 25 as compared with the end of the first reflecting surface 27a on the light emitting unit 25 side, or is located at a short distance. It is comprised so that it may do. Therefore, it is possible to make it difficult to reflect the reflected light of the first reflecting surface 27 a to the facing side of the light receiving unit 26.

  Therefore, the reflecting unit 27 can reflect most of the reflected light of the first reflecting surface 27a toward the light receiving unit 26 via the second reflecting surface 27b.

  Therefore, the level of stray light can be greatly reduced as compared with the case where the reflected light is reflected to the facing side of the light receiving unit 26. Therefore, the photoelectric smoke detector of the present invention can suppress erroneous detection due to stray light.

  The end of the second reflecting surface 27b on the light emitting unit 25 side is configured not to interfere with the optical axis A1 of the light emitting unit 25. Further, the second reflecting surface 27 b is inclined so that an extension line on the light emitting portion 25 side of the second reflecting surface 27 b is directed toward the center of the light emitting portion 25.

  By disposing the second reflecting surface 27b so inclined, the reflected light of the second reflecting surface 27b can be favorably reflected toward the light receiving unit 26.

(Wall shape)
Of the above-described bowl-shaped wall portion 23, the shape of the wall portion 23 (mainly the lower wall portion 23 in FIG. 2) where the reflecting portion 27 is not integrally formed is generally as follows. That is, the wall main body 31 extending along the outer periphery of the housing 21, the first extension 32 extending in the inner diameter direction from the clockwise end of the wall main body 31, and the inner diameter from the counterclockwise end of the wall main body 31. It has the 2nd extension part 33 extended. The first extension portion 32 extends in an inclined posture of about 45 ° with respect to the outer peripheral surface of the housing 21. The second extension portion 33 is further inclined to the right side of the figure at an angle of about 30 ° from the base end portion 33a and a short base end portion 33a extending from the counterclockwise end portion of the wall main body 31 at a substantially right angle in the inner diameter direction. The intermediate portion 33b that extends and the inclined flange-shaped portion 33c that extends right and left from the tip of the intermediate portion 33b to the right and left. The installation angles described above are merely examples, and are not limited to these.

  The wall body 31, the first extension portion 32, and the base end portion 33a of the second extension portion 33 constitute a pocket portion 23P having a bottomed cup shape that is open to the inner diameter side in cooperation with each other. ing. The pocket portion 23P has a function of trapping and accumulating dust that has entered the housing 21 mainly through an upper gap at the bottom thereof. Since the bottom surface of the pocket portion 23P is surrounded by the base end portion 33a of the first extension portion 32 and the second extension portion 33, dust accumulated at the bottom portion of the pocket portion 23P is caused by air current in the housing 21 or vibration transmitted from the outside. It is difficult to soar inside the housing 21.

  The base end portion 33a, the intermediate portion 33b, and the outer diameter side portion of the flange-shaped portion 33c cooperate with each other to form a bottomed cup-shaped space, and the first extension portion of the wall portion 23 adjacent in the counterclockwise direction. By extending 32 toward this space, a first U-shaped flow path L1 is formed on the outer periphery of the first extension portion 32.

  Similarly, the inner diameter side portion of the flange-shaped portion 33c, the intermediate portion 33b, the base end portion 33a, the wall main body 31, and the first extension portion 32 also cooperate with each other to form a bottomed cup-shaped space. The outer diameter side portion of the flange-like portion 33c of the wall portion 23 adjacent to the direction extends so as to enter this space, so that the second U-shaped flow is formed on the outer periphery of the outer diameter-side portion of the flange-like portion 33c. A path L2 is formed.

  These two U-shaped flow paths L1 and L2 are continuously connected to each other to form one reverse S-shaped labyrinth portion L.

  The shape of the wall portion 23 integrally formed with the reflecting portion 27 includes a shaft portion 34 formed at the center in plan view, and arm portions 35 and 36 extending on both sides of the shaft portion 34. It has become. The arm portion 35 is formed with a first reflecting surface 27a, and the shaft portion 34 is formed with a second reflecting surface 27b on the optical axis A1 side. Flange-like portions 35a and 36a extending at right angles toward the outer peripheral side of the housing 21 are formed at the tips of the arm portions 35 and 36, respectively. A U-shaped channel is also formed on the outer periphery of each of the flange-like portions 35a and 36a.

(Other configurations)
The light receiving unit 26 is disposed at a position for receiving the reflected light reflected by the second reflecting surface 27b. Further, a light shielding wall 28 that shields a part of the reflected light is provided between the light receiving unit 26 and the second reflecting surface 27b. The extension line on the light emitting part 25 side of the light shielding wall 28 is configured by inclining the light shielding wall 28 toward the center of the light emitting part 25.

By providing the light shielding wall 28 as in this configuration, a part of the reflected light of the second reflecting surface 27b, for example, the peripheral part of the light flux of the reflected light is shielded, and the reflected light that is not shielded is received by the light receiving unit 26. It can be made incident. As a result, the level of stray light caused by the peripheral portion of the reflected light beam can be significantly reduced.
Further, by arranging the light shielding wall 28 so as to be inclined in this manner, most of the reflected light of the light shielding wall 28 that has received the reflected light of the second reflecting surface 27 b is reflected to the facing side of the light receiving unit 26. Can do.

  Therefore, with the photoelectric smoke detector of this configuration, it is possible to further suppress erroneous detection due to stray light.

  On the light-receiving portion 26 side of the light-shielding wall 28, a convex portion 28a that prevents intrusion of external light and dust is formed. The convex portion 28a can catch relatively large dust having a size of about 5 mm, for example.

  Between the condensing lens 25L of the light emitting unit 25 and the condensing lens 26L of the light receiving unit 26, a blocking wall 24 that blocks direct light from the light emitting unit 25 toward the light receiving unit 26 is provided. Therefore, the light emitted from the light emitting unit 25 does not reach the light receiving unit 26 as it is, and the light receiving unit 26 can receive only the scattered light formed by smoke when smoke flows into the smoke sensing chamber 22. .

  The blocking wall 24 is slightly located outside the smoke detection region 22A and is disposed so as to be sufficiently away from the optical axis A2 of the light receiving unit 26. Therefore, even if dust accumulates on the blocking wall 24, scattered light caused by the dust is difficult to be detected by the light receiving unit 26.

  In the smoke detection region 22A, a collective groove portion 37 is formed so as to substantially overlap the smoke detection region 22A. In this embodiment, the collective groove portion 37 is formed with collective groove portions 37A and 37B composed of a plurality of groove portions 37a on both the housing lid member 21A on the upper surface side of the housing 21 and the housing main body 21B on the lower surface side. The case where it was set as the aspect which performed is demonstrated. Each groove portion 37a is formed by a vertical wall 37b formed substantially vertically and an inclined wall 37c formed inclined. The vertical wall 37 b is formed so as to face the light receiving unit 26.

  When the dust that has entered the housing 21 falls in the smoke detection region 22A, it falls into the collecting groove 37. At this time, dust accumulates on the inclined wall 37c. Since the inclined wall 37c is formed so as not to face the light receiving unit 26, scattered light caused by dust accumulated on the inclined wall 37c is difficult to be detected by the light receiving unit 26.

  The present invention includes a housing having a plurality of labyrinth-like wall portions juxtaposed via a gap so as to allow smoke from the outside to flow in and block light from the outside, and to irradiate the inside of the housing with light A light-emitting unit; a light-receiving unit that detects scattered light due to smoke that has flowed into the housing; and a reflective unit that is disposed to face the light-emitting unit and reflects light emitted from the light-emitting unit. It can be used for photoelectric smoke detectors.

A1 Optical axis 21 Housing 23 Labyrinth-like wall portion 24 Blocking wall 25 Light emitting portion 26 Light receiving portion 27 Reflecting portion 27a First reflecting surface 27b Second reflecting surface

Claims (3)

A housing having a plurality of labyrinth-like wall portions juxtaposed via a gap so as to allow smoke from outside and block light from outside;
A light emitting unit for irradiating light inside the housing;
A light receiving unit for detecting scattered light from smoke flowing into the housing;
A reflective portion that is disposed opposite to the light emitting portion and reflects light emitted from the light emitting portion;
A photoelectric smoke detector comprising:
The reflecting portion includes a first reflecting surface inclined with respect to the optical axis of the light emitting portion,
A second reflecting surface that receives the reflected light reflected by the first reflecting surface;
The light emitting unit side of the second reflective surface is inclined toward the optical axis, and the end of the light emitting unit side of the second reflective surface is the end of the light emitting unit of the first reflective surface. A photoelectric smoke detector having a distance to the light emitting portion equal to or close to the end portion on the side.   The photoelectric smoke detector according to claim 1, wherein an extension line on the light emitting unit side of the second reflecting surface is directed to the light emitting unit.   The light receiving unit is disposed at a position to receive the reflected light reflected by the second reflecting surface, and includes a light shielding wall that blocks part of the reflected light between the light receiving unit and the second reflecting surface. The photoelectric smoke detector according to claim 1 or 2.

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