JP6544974B2 - smoke detector - Google Patents

Description

  The present invention relates to a smoke sensor that senses a fire by detecting scattered light from smoke.

  Conventionally, in the scattered light type smoke detector, as shown in FIG. 8 for example, the sensor main body 100 is provided with a substantially cylindrical smoke detection unit 102, and the light emission unit 104 is provided in the smoke detection space inside the smoke detection unit 102. The light receiving portion 106 is disposed such that the optical axes thereof intersect at the center, and a labyrinth structure in which a plurality of labyrinth walls 108 are disposed annularly is provided around the smoke detection portion 102.

  The labyrinth structure prevents the ingress of noise light from the outside to the light receiving unit 106 and the incidence of internally reflected light from the light beam from the light emitting unit 104 by the labyrinth wall 108. For this purpose, the labyrinth wall 108 is erected. It should be arranged to narrow between the walls 108.

JP 2001-126165 A JP, 2006-099788, A Japanese Patent Application Laid-Open No. 6-076182

  However, in the smoke sensor provided with the conventional labyrinth structure, the inflow of smoke to the smoke detection portion is impaired by the labyrinth structure, and the inflow of smoke must be slower than in the case where the labyrinth structure is not provided. In addition, the labyrinth structure complicates the structure of the smoke detection unit, resulting in an increase in cost.

  An object of the present invention is to provide a smoke detector which can realize good smoke inflow by suppressing internal reflection by light from a light emitting part without providing a labyrinth structure.

[Smoke detector using light emitting element and polarization filter]
(smoke detector)
The invention relates to a smoke sensor,
A sensor main body provided with a smoke detector;
An outer cover provided with a smoke inlet for taking smoke into the smoke detector;
A light emitting element disposed in the smoke detection unit and emitting a light beam, and a light emitting unit disposed in front of the light emitting element and including a polarization filter that converts the light beam of the light emitting element into a polarized beam and emits the light beam;
A light receiving unit including a light receiving element disposed at a portion of the smoke detection unit where the polarized beam from the light emitting unit does not directly enter and which receives scattered light from the smoke of the polarized beam;
Have
The smoke detector does not have a labyrinth structure to prevent light from the outside and polarized light from entering the light receiving part by light from outside and limits the light receiving field of the light receiving element to the light receiving element of external light Provide a structure to prevent
Let the irradiation site of the smoke detection part to which the polarized light beam from the light emission part is irradiated be an irradiation plane,
The polarization filter is set so that the polarization direction of the polarized beam irradiated on the irradiation plane is parallel to the incident plane, and the light emitting unit is set so that the incident angle of the polarized beam on the irradiation plane is a predetermined angle with low reflectance. Is placed.

(Scattered light type smoke detection structure in which the light emitting unit and the light receiving unit are arranged around the vertical)
The smoke detection unit is provided with a smoke detection space that closes the upper and lower surfaces and opens to the periphery to allow smoke to flow in,
The light emitting portion is disposed on one of the upper and lower surfaces of the smoke detection space so as to obliquely irradiate a polarized beam toward the other surface of the upper and lower surfaces of the smoke detection space, and the polarized beam irradiated to the smoke detection space Place the light receiver to receive the scattered light from the
The polarization filter is set so that the polarization direction of the polarized beam to be irradiated to the other surface of the upper and lower surfaces is parallel to the incident surface, and the incident angle to the other surface of the upper and lower surfaces of the polarized beam is low The light emitting unit is disposed to have a predetermined angle.

(Scattered light type smoke detection structure in which the light emitting part and the light receiving part are arranged horizontally)
The smoke detection unit is provided with a smoke detection space that closes the upper and lower surfaces and opens to the periphery to allow smoke to flow in,
Place the light emitting unit and the light receiving unit around the horizontal of the smoke detection space,
The irradiation area around the smoke detection part to which the polarized light beam from the light emission part is irradiated is taken as an irradiation plane,
The polarization filter is set so that the polarization direction of the polarized beam irradiated on the irradiation plane is parallel to the incident plane, and the light emitting unit is set so that the incident angle of the polarized beam on the irradiation plane is a predetermined angle with low reflectance. Place.

(Formation of irradiated plane by insect screen)
The irradiation plane is formed by an insect screen placed around the smoke detection space.

(Formation of reflective wall)
The irradiation plane is formed by the reflecting wall surface standing up at the peripheral position of the smoke detection space to which the polarized beam is irradiated.

(Brewster corner)
The incident angle of the polarized beam with respect to the irradiation plane is a predetermined Brewster's angle at which the reflectance is zero.

[Smoke detector using laser diode]
(smoke detector)
In another form of the invention, in the smoke detector:
A sensor main body provided with a smoke detector;
An outer cover provided with a smoke inlet for taking smoke into the smoke detector;
A light emitting unit provided with a laser diode disposed in the smoke detection unit and emitting a polarized laser beam;
A light receiving unit including a light receiving element disposed at a portion of the smoke detection unit where the laser beam from the light emitting unit does not directly enter, and which receives scattered light from the smoke of the laser beam;
Have
The smoke detector does not have a labyrinth structure to prevent light from the outside and laser light from entering the light receiving part of the light receiving element, and limits the light receiving field of the light receiving element to the light receiving element of external light. Provide a structure to prevent
Let the irradiation site of the smoke detection unit to which the laser beam from the light emitting unit is irradiated be an irradiation plane,
The laser diode is set so that the polarization direction of the laser beam irradiated to the irradiation plane is parallel to the incident plane, and the light emitting unit is further adjusted so that the incident angle to the irradiation plane of the laser beam is a predetermined angle with low reflectance. Is placed.

(Scattered light type smoke detection structure in which the light emitting unit and the light receiving unit are arranged around the vertical)
The smoke detection unit is provided with a smoke detection space that closes the upper and lower surfaces and opens to the periphery to allow smoke to flow in,
A laser beam is disposed to irradiate the laser beam obliquely toward the other surface of the upper and lower surfaces of the smoke detection space on one side of the upper and lower surfaces of the smoke detection space, and a laser beam irradiated to the smoke detection space Place the light receiver to receive the scattered light from the
The laser diode is set so that the polarization direction of the laser beam irradiated to the other surface of the upper and lower surfaces is parallel to the incident surface, and the incident angle to the other surface of the upper and lower surfaces of the laser beam is low The light emitting unit is disposed to have a predetermined angle.

(Scattered light type smoke detection structure in which the light emitting part and the light receiving part are arranged horizontally)
The smoke detection unit is provided with a smoke detection space that closes the upper and lower surfaces and opens to the periphery to allow smoke to flow in,
Place the light emitting unit and the light receiving unit around the horizontal of the smoke detection space,
The irradiation area around the smoke detection part to which the laser beam from the light emission part is irradiated is taken as an irradiation plane,
The laser diode is set so that the polarization direction of the laser beam irradiated to the irradiation plane is parallel to the incident plane, and the light emitting unit is further adjusted so that the incident angle to the irradiation plane of the laser beam is a predetermined angle with low reflectance. Place.

(Formation of irradiated plane by insect screen)
The irradiation plane is formed by an insect screen placed around the smoke detection space.

(Formation of reflective wall)
An irradiation plane is formed by a reflecting wall surface standing up at a peripheral position of the smoke detection space to which the polarized beam is irradiated.

(Brewster corner)
The incident angle of the laser beam with respect to the irradiation plane is a predetermined Brewster's angle at which the reflectance is zero.

  According to the smoke detector of the present invention, a light beam from a light emitting element such as an LED provided in a light emitting portion is converted into a polarized beam by passing it through a polarizing filter disposed in front, and the polarized beam is irradiated By making the irradiation site inside the plane a plane and making the polarization direction of the polarized beam to be irradiated to this plane parallel to the plane of incidence (horizontal polarization incidence), the incident angle is a predetermined angle with low reflectance Internal light reflection is almost completely eliminated by setting the incident angle to the Brewster's angle at which the reflectance is zero, thereby substantially eliminating the internal reflection, and receiving light without smoke. It is possible to suppress the incident light to the part and improve the S / N ratio of the light reception output.

In addition, it is possible to eliminate the need for the labyrinth structure provided in the smoke detection section by significantly reducing internal reflection due to light from the light emitting section or making it substantially zero, thereby improving the inflow of smoke into the smoke detection section. It allows improving the detection sensitivity of the smoke from a fire with.

  In addition, eliminating the labyrinth structure simplifies the structure of the sensor and enables cost-down.

  Further, the same effect can be obtained by providing a laser diode in place of the light emitting element of the light emitting portion and the polarization filter and irradiating a laser beam with polarization.

Explanatory drawing which showed embodiment of the smoke detector provided with the scattered-light-type smoke-detection structure which intersects the optical axis in the perpendicular direction of smoke detection part An explanatory view showing the reflection of light incident on a medium Explanatory drawing showing vertical polarization incidence and horizontal polarization incidence of polarized beam to medium surface Explanatory drawing which took out and showed the horizontal polarization incidence to the bottom of the polarization beam by the light emission part of FIG. 1 Explanatory drawing which showed embodiment of the smoke sensor provided with the scattered-light-type smoke-detection structure which crosses an optical axis by the horizontal direction of smoke detection part Explanatory drawing which showed the insect net of the flat net structure used by embodiment of FIG. 5 contrasted with the insect net using a wire net. Explanatory drawing which showed other embodiment of the smoke detector provided with the scattered-light-type smoke-examination structure which crosses an optical axis around the level of smoke detection part Explanatory view showing a conventional smoke sensor having a labyrinth structure

[Embodiment of smoke detector crossing the optical axis in the horizontal direction]
(Structure of smoke detector)
FIG. 1 is an explanatory view showing an embodiment of a smoke sensor provided with a scattered light type smoke detection structure which intersects the optical axis in the vertical direction of the smoke detection portion, and a cross section is shown in FIG. The plane which looked at the smoke detection part from lower side is shown to (B). Further, FIG. 1A is a cross-sectional view taken along the line XX in FIG.

  As shown in FIG. 1, the smoke sensor 10 comprises a sensor body 12 and an outer cover 14. A smoke detector 18 is provided in the sensor main body 12, and a circuit board 15 is stored in the circuit storage 17 on the upper side of the smoke detector 18.

  The smoke detector 18 has a substantially cylindrical shape that is open to the periphery and closed up and down, and forms a smoke detection space 20 inside. A light emitting unit 22 and a light receiving unit 24 are disposed obliquely downward on the upper side of the smoke detection space 20 so that the optical axes 34 and 35 intersect at the smoke detection point P in the smoke detection space 20.

  The light emitting unit 22 is provided with a light emitting element 26 such as an LED, and a polarization filter (polarizer) 28 is disposed in front of the light emitting element 26 to make the light beam (non-polarization beam) from the light emitting element 26 have a predetermined polarization direction. The light beam is converted into a polarized light beam (linearly polarized light beam) and emitted toward the bottom surface 32 located below the detection space 20.

  The light receiving unit 24 includes a light receiving element 30 such as a photodiode (PD), and is disposed at a site where the polarized beam from the light emitting unit 22 is not directly incident, and the scattered light of the polarized beam by the smoke flowing into the smoke detection space 20 The amount of scattered light is detected.

  The outer cover 14 accommodates the sensor body 12 inside, and a smoke inflow hole 16 for taking in smoke is provided in the cover portion facing the outer periphery of the smoke detection portion 18 so as to surround the outside of the smoke detection space 20 There is. In addition, an insect screen 46 is annularly disposed inside the smoke inlet 16.

In this scattered light type smoke detection structure, in the present embodiment, the irradiation site of the smoke detection unit 18 to which the polarized light beam from the light emitting unit 22 is irradiated is a bottom surface ( irradiation surface ) 32 serving as an irradiation plane. The polarization direction around the optical axis of the polarizing filter 28 is set so that the polarization plane of the incident polarization beam becomes horizontal polarization (P polarization) horizontal to the incidence plane, and further, becomes the irradiation plane of the polarization beam The light emitting portion 22 is disposed obliquely downward so that the incident angle α with respect to the bottom surface 32 is a predetermined angle with low reflectance, and the light reflected from the bottom surface 32 is suppressed.

Here, the incident angle α at which the polarized beam from the light emitting unit 22 enters as horizontal polarization is preferably a predetermined Brewster angle at which the reflectance is zero. The Brewster's angle (polarization angle) is an incident angle at which the reflectance of p-polarized light becomes zero at the interface between substances having different refractive indexes .

  As described above, by suppressing the reflected light of the bottom surface 32 by the polarized light beam from the light emitting unit 22, the labyrinth structure provided as shown in FIG. 8 around the smoke detector 18 is unnecessary.

(Reflection of polarized beam)
FIG. 2 is an explanatory view showing reflection of light incident on a medium, and FIG. 2 (A) shows the relationship between refracted light and reflected light with respect to incident light, and FIG. 2 (B) shows horizontally polarized light (p polarized light) The characteristic graph of the amplitude reflectance to incidence angle alpha of perpendicular polarization (s polarization) is shown.

As shown in FIG. 2A, consider a light beam which enters the medium of refractive index n2 from the medium 1 (here, air) of refractive index n1. According to Snell's law, the relationship between the incident angle α and the angle β of refracted light is n1 / n2 = sin β / sin α
It becomes.

When a light beam enters a medium with a refractive index n2 at an incident angle α, the reflectance on the incident surface is determined by the polarization plane, and the amplitude reflectance of horizontally polarized light is Rp, and the amplitude reflectance of vertically polarized light is Rs, Given by
Rp = tan (α-β) / tan (α + β)
Rs = -sin (α-β) / sin (α + β)
The graph in FIG. 2B shows the change in the amplitude reflectance Rp of horizontal polarization and the amplitude reflectance Rs of vertical polarization with respect to the incident angle α, and indicates that the reflectance increases as the incident angle α increases. It is done.

  Here, looking at the amplitude reflectance Rp of horizontally polarized light, the amplitude reflectance Rp decreases with the increase of the incident angle α, and when it reaches 55 ° known as Brewster's angle (polarization angle), the amplitude reflectance Rp Becomes zero and then increases rapidly.

  In addition, looking at the amplitude reflectance Rs of the vertical polarization, the amplitude reflectance Rs also increases with the increase of the incident angle α, and the amplitude reflectance Rs rapidly increases when it exceeds 40 °.

  FIG. 3 is an explanatory view showing the incidence of the polarized beam on the irradiation plane, FIG. 3 (A) shows the incidence of horizontally polarized light, and FIG. 3 (B) shows the incidence of vertically polarized light.

  As shown in FIG. 3A, a polarized beam (linearly polarized beam) 38 incident on the irradiation plane 40 along the optical axis 34 has a polarization plane 42 in the amplitude direction, and in the case of horizontal polarization, On the other hand, the polarization plane 42 of the polarized beam 38 is incident so as to be horizontal. The characteristic of the amplitude reflectance Rp shown in FIG. 2B is obtained by changing the incident angle α for this horizontally polarized light, and the reflectance is zero when the incident angle α is set to 55 ° that is the Brewster angle. It becomes.

  On the other hand, in the case of vertical polarization, as shown in FIG. 3B, the polarization plane 42 of the polarized beam 38 is incident on the incident plane 41 so as to be vertical. The characteristic of the amplitude reflectance Rs shown in FIG. 2 (B) can be obtained by changing the incident angle α for this vertical polarization.

  Therefore, in the embodiment of FIG. 1, the incident of horizontally polarized light shown in FIG. 3A is applied to suppress the amount of light reflected by internal reflection.

(Configuration to suppress internal reflection)
FIG. 4 is an explanatory view showing the incidence of horizontally polarized light on the bottom surface of the polarized beam by the light emitting unit of FIG.

  As shown in FIG. 4, in order to realize the suppression of the reflected light due to the incidence of the horizontally polarized light shown in FIG. 3A, the polarization filter 28 is provided in front of the light emitting element 26 provided in the light emitting unit 22 to intermittently emit light. The non-polarized beam (randomly polarized beam) from the light emitting element 26 is converted into a polarized beam (linearly polarized beam) 38 and irradiated to the smoke detection space.

Further, the irradiation site of the polarized beam 38 is the bottom surface 32 of the smoke detection unit 18 corresponding to the irradiation plane 40 in FIG. 3A, and the incident angle α of the polarized beam 38 with respect to the bottom surface 32. The light emitting unit 22 is disposed in the smoke detection unit 18 such that the angle α between the axis 34 and the perpendicular 36 is a predetermined Brewster angle corresponding to the synthetic resin that is the material of the smoke sensor 10, for example 55 °. Ideally, the light quantity of internal reflection approaches zero.

  As a result, the smoke detector 10 of FIG. 1 does not need to have a labyrinth structure in the smoke detection unit 18, and the insect screen 46 may be disposed inside the smoke inflow hole 16 provided in the outer cover 14.

  Further, the influence of disturbance light entering from the outside is limited by limiting the light receiving field of the light receiving element 30 provided in the light receiving unit 24 so that the disturbance light from the smoke inflow hole 16 of the outer cover 14 does not enter. It can be a level without problems. Further, the electric circuit for processing the light reception signal from the light receiving element 30 mounted on the circuit board 15 may be provided with a filter for cutting a DC component due to steady disturbance light, thereby eliminating the influence of disturbance light. it can.

[Embodiment of smoke detector crossing the optical axis in the horizontal direction]
(Structure of smoke detector)
FIG. 5 is an explanatory view showing an embodiment of a smoke detector provided with a scattered light type smoke detection structure which intersects the optical axis in the horizontal direction of the smoke detection portion, and a cross section is shown in FIG. The plane which looked at the smoke detection part from lower side is shown to (B). Moreover, FIG. 5 (A) becomes an XX cross section of FIG. 5 (B).

  As shown in FIG. 5, the smoke detector 10 is composed of a sensor body 12 and an outer cover 14, and the sensor body 12 is provided with a smoke detection unit 18, and a circuit is provided in the circuit storage unit above the smoke detection unit 18. The substrate 15 is housed.

  The smoke detector 18 has a substantially cylindrical shape that is open to the periphery and closed up and down, and forms a smoke detection space 20 inside. The light emitting unit 22 and the light receiving unit 24 are disposed at a predetermined position that is horizontally rotated with respect to the smoke detection space 20, and the light axes 34 and 35 intersect at the smoke detection point P in the smoke detection space 20. doing.

  A light emitting element 26 such as an LED is provided in the light emitting section 22, and a polarizing filter 28 is disposed in front of the light emitting element 26. A light beam from the light emitting section 22 is converted into a polarized beam having a predetermined polarization direction It is irradiating toward the side of 20.

  The light receiving unit 24 includes a light receiving element 30 such as a photodiode (PD), and is disposed at a site where the polarized beam from the light emitting unit 22 is not directly incident, and the scattered light of the polarized beam by the smoke flowing into the smoke detection space 20 The amount of scattered light is detected.

  The outer cover 14 accommodates the sensor body 12 inside, and a smoke inflow hole 16 for taking in smoke is provided in the cover portion facing the outer periphery of the smoke detection portion 18 so as to surround the outside of the smoke detection space 20 There is.

  The site to which the polarized light beam from the light emitting unit 22 is irradiated needs to be the irradiation plane 40 shown in FIG. 3A in order to suppress the reflected light, and in the present embodiment, for example, a rectangular insect repellent The network 48 is disposed in the smoke detection unit 18, and the polarization direction of the polarized beam irradiated toward the flat screen of the insect screen 48 passing the light axis 34 from the light emitting unit 22 at point Q is horizontal to the incident surface Polarization filter 28 is set. The insect screen 48 is not limited to a rectangle, as long as it has a flat screen in the beam irradiation range centered on the point Q through which the optical axis 34 passes.

  Here, the insect screen 48 used in the present embodiment is not the insect screen 46 in which resin or metal wires shown in FIG. 6A are knitted, but as shown in FIG. A flat screen made by punching or etching a flat plate is used.

  In addition, the incident angle α of the polarized beam 38 with respect to the flat mesh plane of the insect screen 48 from the light emitting section 22, that is, the optical axis 34 of the light emitting section 22 and the perpendicular 36 from the point Q through which the optical axis 34 of the flat mesh plane passes. The angle α is arranged to be a predetermined Brewster angle corresponding to the material of the insect screen 48, and ideally the amount of light of internal reflection approaches zero.

As a result, the smoke sensor 10 of FIG. 5 does not have to be provided with a labyrinth structure in the smoke detection unit 18. Further, with respect to the influence of disturbance light entering from the outside, the light reception field of the light receiving element 30 provided in the light receiving unit 24 is limited, and disturbance light from the smoke inflow hole 16 of the outer cover 14 is prevented from entering. Further, the electric circuit for processing the light reception signal from the light receiving element 30 mounted on the circuit board 15 is provided with a filter for cutting the DC component due to the steady disturbance light, thereby eliminating the influence of the disturbance light.

  If it is difficult to provide the insect screen 48 having a flat screen due to the design and space of the smoke sensor 10, the flat screen shown in FIG. You may arrange | position around the circumference | surroundings of the part 18. FIG. In this case, the incident angle of the polarized beam with respect to the annular insect screen is distributed, for example, within a range of plus or minus a few degrees around the incident angle of 0 °, but the reflectance is determined by the characteristics of the amplitude reflectance Rp in FIG. It becomes 0.2 or less, and the effect which suppresses reflected light is fully acquired.

[Embodiment of smoke detector provided with a reflecting wall]
7 is an explanatory view showing another embodiment of a smoke sensor provided with a scattered light type smoke detection structure in which the optical axis is crossed in the horizontal direction of the smoke detection portion, and a cross section is shown in FIG. The plane which looked at the smoke detection part from lower side in FIG. 7 (B) is shown. Moreover, FIG. 7 (A) becomes an XX cross section of FIG. 7 (B).

  As shown in FIG. 7, the smoke sensor 10 according to the present embodiment stands the reflecting wall 50 at the site where the polarized beam from the light emitting unit 22 is irradiated, and reflects the polarized plane of the polarized beam from the light emitting unit 22. The polarization filter 28 is set so that the polarization direction of the polarized beam irradiated toward the flat wall of the wall 50 is horizontal to the incident plane.

  Further, the incident angle α of the polarized beam 38 with respect to the flat reflecting surface of the reflecting wall 50 from the light emitting part 22, that is, the perpendicular 36 from the point Q through which the optical axis 34 of the light emitting part 22 and the optical axis 34 of the reflecting wall 50 pass. The reflecting wall 50 is disposed such that the angle α is a predetermined Brewster angle corresponding to the synthetic resin that is the material of the smoke sensor 10, for example 55 °, and the light quantity of internal reflection approaches zero.

  Also, an insect screen 46 (FIG. 6 (B) in which resin or metal wire shown in FIG. 6 (A) is woven at a position inside the smoke inflow hole 16 of the outer cover 14 surrounding the smoke detection section 18 ) May be arranged in a ring. The other structure is the same as that of the embodiment shown in FIG.

  This embodiment is suitable when it is difficult to provide a rectangular insect screen 48 having a flat screen in the smoke detection unit 18 as in the embodiment of FIG. 5, and it is preferable to By making the light incident on the reflecting wall 50 according to the incident angle as the star angle, it is ideally possible to bring the light quantity of the internal reflection close to zero, and it is not necessary to provide the labyrinth structure in the smoke detection unit 18.

[Embodiment in which a laser diode is used for the light emitting portion]
In the embodiment of the smoke sensor shown in FIGS. 1, 5 and 7, a laser diode is provided in place of the light emitting element 26 and the polarization filter 28 provided in the light emitting unit 22. The laser diode emits a highly polarized laser beam, as is well known.

  The laser beam (polarization beam) from the laser diode provided in the light emitting unit 22 is made incident on the bottom surface 32 serving as the irradiation plane in each of FIGS. 1, 5 and 7, the flat screen of the insect screen 48, and the reflecting wall 50. .

  In this case, with respect to the polarization plane of the laser beam, the polarization direction of the laser beam to be irradiated to the bottom plane 32, the flat screen plane of the insect screen 48, and the irradiation plane of the reflecting wall 50 in each of FIGS. The laser diode is set to be horizontal to the above, and the incident angle α of the laser beam with respect to each irradiation plane is taken as Brewster's angle.

  As a result, the amount of light due to internal reflection of the laser beam can be ideally brought close to zero, and it is not necessary to provide a labyrinth structure in the smoke detection unit 18.

[Modification of the present invention]
Although the above embodiment exemplifies a scattered light type smoke detection structure in which the light emitting unit and the light receiving unit are disposed in the vertical direction and the horizontal direction of the smoke detecting unit, the light emitting unit has an appropriate solid angle other than the vertical direction and the horizontal direction. The same can be applied to a scattered light type smoke detection structure in which the light receiving portion is disposed.

  In the above embodiment, although the reflectance is brought close to zero by setting the incident angle of the polarized beam or the laser beam to the irradiation plane as the Brewster's angle, the Brewster is as close as possible due to the relationship of the smoke sensor design and space. It also includes the case where the incident angle is close to the angle. The range of the incident angle is a range in which the amplitude reflectance Rp does not exceed, for example, 0.2 in FIG. 2 (B).

  Further, the present invention is not limited to the above-described embodiment, includes appropriate modifications that do not impair the objects and advantages thereof, and is not limited by the numerical values shown in the above-described embodiment.

10: smoke detector 12: sensor main body 14: outer cover 15: circuit board 16: smoke inlet 18: smoke detector 20: smoke detection space 22: light emitter 24: light receiver 26: light emitting element 28: polarization filter 30 : Light receiving element 32: Bottom surface 34, 35: Optical axis 38: Polarized beam 40: Irradiation plane 42: Polarization plane 46, 48: Insect screen 50: Reflective wall

Claims (12)

A sensor main body provided with a smoke detector;
An outer cover provided with a smoke inlet for taking smoke into the smoke detection unit;
A light emitting element disposed in the smoke detection unit and emitting a light beam, and a light emitting unit disposed in front of the light emitting element and including a polarization filter that converts the light beam of the light emitting element into a polarized beam and emits the light beam;
A light receiving unit including a light receiving element disposed at a site of the smoke detection unit where the polarized light beam from the light emitting unit does not directly enter and which receives scattered light from smoke of the polarized beam;
Have
The light receiving area of the light receiving element is limited and the light from the outside is provided in the smoke detection section without providing a labyrinth structure for preventing the light from the outside and the internally reflected light by the polarized beam from entering the light receiving section. Provide a structure that prevents the light from entering the
The irradiation site of the smoke detection unit to which the polarized light beam from the light emitting unit is irradiated is taken as an irradiation plane;
The polarization filter is set so that the polarization direction of the polarized beam irradiated to the irradiation plane is parallel to the incident plane, and the incident angle of the polarized beam to the irradiation plane is a predetermined angle with a low reflectance. A smoke detector characterized in that the light emitting unit is arranged to be.
The smoke sensor according to claim 1,
The smoke detector has a smoke detection space that closes the upper and lower surfaces and opens to the periphery to allow smoke to flow therein.
The light emitting unit is disposed on one side of the upper and lower surfaces of the smoke detection space so as to obliquely irradiate a polarized beam toward the other surface of the upper and lower surfaces of the smoke detection space, and Arranging the light receiving unit to receive scattered light from the smoke of the polarized beam irradiated;
The polarization filter is set so that the polarization direction of the polarized beam irradiated to the other upper and lower surfaces is parallel to the incident surface, and the incident angle of the polarized beam to the other upper and lower surfaces is reflected. A smoke detector characterized in that the light emitting unit is disposed to have a predetermined angle with a low rate.
The smoke sensor according to claim 1,
The smoke detector has a smoke detection space that closes the upper and lower surfaces and opens to the periphery to allow smoke to flow therein.
Arranging the light emitting unit and the light receiving unit around the horizontal of the smoke detection space;
An irradiation area around the smoke detection unit to which the polarized light beam from the light emitting unit is irradiated is set as an irradiation plane;
The polarization filter is set so that the polarization direction of the polarized beam irradiated to the irradiation plane is parallel to the incident plane, and the incident angle of the polarized beam to the irradiation plane is a predetermined angle with low reflectance. A smoke detector characterized in that the light emitting unit is disposed in
4. A smoke sensor according to claim 3, wherein the irradiation plane is formed by an insect screen disposed around the smoke detection space.
4. The smoke detector according to claim 3, wherein a reflective wall is formed at a peripheral position of the smoke detection space to which the polarized beam is irradiated.
The smoke sensor according to any one of claims 1 to 5, wherein the incident angle of the polarized beam with respect to the irradiation plane is a predetermined Brewster angle at which the reflectance is zero. vessel.
A sensor main body provided with a smoke detector;
An outer cover provided with a smoke inlet for taking smoke into the smoke detector;
A light emitting unit including a laser diode disposed in the smoke detection unit and emitting a polarized laser beam;
A light receiving unit including a light receiving element disposed at a site of the smoke detection unit where the laser beam from the light emitting unit is not directly incident, and in which scattered light by smoke of the laser beam is incident;
Have
In the smoke detection section, the light receiving field of the light receiving element is limited without providing a labyrinth structure for preventing the light from the outside and the internally reflected light by the laser beam from being incident on the light receiving section, and the light from the outside is limited. Provide a structure that prevents the light from entering the
The irradiation site of the smoke detection unit to which the laser beam from the light emitting unit is irradiated is taken as an irradiation plane;
The laser diode is set so that the polarization direction of the polarized beam irradiated to the irradiation plane is parallel to the incident plane, and the incident angle of the laser beam to the irradiation plane is a predetermined angle with low reflectance. A smoke detector characterized in that the light emitting unit is disposed as follows.
The smoke sensor according to claim 7,
The smoke detector has a smoke detection space that closes the upper and lower surfaces and opens to the periphery to allow smoke to flow therein.
The light emitting unit is disposed on one side of the upper and lower surfaces of the smoke detection space so as to obliquely irradiate the laser beam toward the other surface of the upper and lower surfaces of the smoke detection space, and The light receiving unit is disposed to receive scattered light from the smoke of the irradiated laser beam,
The laser diode is set so that the polarization direction of the laser beam irradiated to the other surface of the upper and lower surfaces is parallel to the incident surface, and the incident angle of the laser beam to the other surface of the upper and lower surfaces is further determined. A smoke detector characterized in that the light emitting portion is disposed so as to have a predetermined angle with low reflectance.
The smoke sensor according to claim 7,
The smoke detector has a smoke detection space that closes the upper and lower surfaces and opens to the periphery to allow smoke to flow therein.
Arranging the light emitting unit and the light receiving unit around the horizontal of the smoke detection space;
An irradiation area around the smoke detection unit to which the laser beam from the light emitting unit is irradiated is set as an irradiation plane;
The laser diode is set so that the polarization direction of the laser beam irradiated to the irradiation plane is parallel to the incident plane, and further, the incident angle of the laser beam to the irradiation plane is a predetermined angle with low reflectance A smoke detector characterized in that the light emitting unit is arranged to be.
The smoke detector according to claim 9, wherein the irradiation plane is formed by an insect screen disposed around the smoke detection space.
The smoke detector according to claim 9, wherein a reflective wall is formed at a peripheral position of the smoke detection space to which the laser beam is irradiated.
  The smoke sensor according to any one of claims 7 to 11, wherein the incident angle of the laser beam with respect to the irradiation plane is a predetermined Brewster angle at which the reflectance is zero. vessel.

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