Invention name: Smoke detector
Technical field
[0001]
　The present invention relates to a photoelectric smoke detector that detects smoke by scattered light.
Background technology
[0002]
　The photoelectric spot type smoke detector utilizes light scattering to detect smoke. In this smoke detector, the light receiving element is arranged at a position deviated from the optical axis of the light emitting element. Then, if there is smoke in the smoke detection section around the optical axis, scattered light is generated and enters the light receiving element to detect the smoke. Patent Document 1 describes a smoke detector that detects smoke by forward scattered light or backscattered light.
Prior art literature
Patent literature
[0003]
Patent Document 1: Japanese Patent Application Laid-Open No. 2015-191462
Outline of the invention
Problems to be solved by the invention
[0004]
　The optical table surrounding the smoke detection unit that detects scattered light is made of black resin or the like. This is to prevent outside light from passing through the optical table and to prevent stray light from being reflected on the inner surface of the optical table and entering the light receiving element. This is to prevent detection.
　On the other hand, in order to detect whether the light emitting element and the light receiving element are functioning normally, there is a technique of using the reflected light that the irradiation light from the light emitting element is reflected without being absorbed inside the optical table. In this case, if the reflected light inside the optical table is too small or too large, it will not function normally.
　An object of the present invention is to set an appropriate amount of reflected light inside the optical table.
Means to solve problems
[0005]
(1) The present invention comprises a smoke introduction unit, a smoke detection unit provided above the smoke introduction unit and surrounded from the side by a peripheral wall, a first light emitting element, and a light receiving element. The light receiving element and the first light emitting element are arranged at a position where the light receiving element receives the forward scattered light when the first irradiation light transmitted from the light emitting element irradiates the smoke in the smoke detection unit. A secondary reflecting plate that forms a secondary reflected light when the first irradiation light is irradiated to the smoke-free portion inside the peripheral wall is provided on the side of the first light emitting element. The secondary reflecting plate is a smoke detector characterized in that the first irradiation light receives and is reflected by the primary reflected light reflected by the peripheral wall, and the generated secondary reflected light is input to the light receiving element. ..
[0006]
　INDUSTRIAL APPLICABILITY According to the present invention, it is possible to increase the reflected light that enters the light receiving element when there is no smoke in the smoke detecting unit, and to inspect the failure between the first light emitting element and the light receiving element.
[0007]
(2) Further, in the present invention, the second irradiation light transmitted from the second light emitting element is located at a position where the light receiving element receives the backward scattered light when the smoke in the smoke detection unit is irradiated with the second irradiation light. The primary reflection region in which the second irradiation light transmitted by the second light emitting element is reflected when the second irradiation light is irradiated to the smoke detection portion having no smoke on the peripheral wall where the two light emitting elements are arranged. A deflecting reflection wall that reflects the second irradiation light in a direction different from the incoming direction, the light receiving element is housed in the light receiving element accommodating wall protruding inward in the peripheral wall, and the second irradiation light is the deflection. The smoke detector according to (1) is characterized in that it is reflected by a reflecting wall and guided to the side of the light receiving element accommodating wall on the side opposite to the second light emitting element. Here, "the light receiving element is housed in the light receiving element accommodating wall protruding inward in the peripheral wall" includes those in which the light receiving element accommodating wall does not surround the light receiving element in a portion other than the peripheral wall.
[0008]
　INDUSTRIAL APPLICABILITY According to the present invention, it is possible to reduce the reflected light that enters the light receiving element when there is no smoke in the smoke detection unit, and to improve the accuracy and quality of smoke detection by improving the SN ratio.
[0009]
(3) Further, the present invention is the smoke detector according to (2), wherein the deflection reflection wall is provided with a portion close to the light receiving element protruding outward.
[0010]
　INDUSTRIAL APPLICABILITY According to the present invention, the reflected light can be guided to a position where light does not enter the light receiving element without narrowing the smoke detection unit.
[0011]
(4) Further, the present invention has a light-shielding plate between the first light-emitting element and the second light-emitting element, and the light-shielding plate is provided with a flat surface along the direction in which the second light-emitting element faces. It is a smoke detector of (2) or (3), which is characterized by being.
[0012]
　According to the present invention, the irradiation light from the first light emitting element directly enters the light receiving unit without hindering the irradiation of the irradiation light to the smoke detection unit and the light input of the scattered light to the light receiving unit. Can be prevented.
Effect of the invention
[0013]
　By setting the amount of reflected light that enters the light receiving element to an appropriate level, it is possible to detect whether the light emitting element and the light receiving element are functioning normally. Further, it is possible to improve the accuracy and quality of smoke detection by improving the SN ratio by preventing excessive reflected light from entering the light receiving element.
A brief description of the drawing
[0014]
FIG. 1 is an exploded perspective view of a smoke detector 1 according to an embodiment of the present invention.
FIG. 2 is a diagram for explaining a cross section of the smoke detector 1 according to the embodiment of the present invention.
FIG. 3 is a diagram for explaining forward scattering in one embodiment of the present invention.
FIG. 4 is a diagram showing a light emitting amount and a light receiving amount in one embodiment of the present invention.
FIG. 5 is a diagram showing an optical table 71 according to an embodiment of the present invention.
FIG. 6 is a view of the sensor base 2 according to the embodiment of the present invention as viewed from diagonally below.
FIG. 7 is a diagram for explaining backscatter in one embodiment of the present invention.
FIG. 8 is a diagram showing the amount of light emitted, the amount of light received by forward scattered light, and the amount of light received by backscattered light in one embodiment of the present invention.
Embodiment for carrying out the invention
[0015]
　Hereinafter, embodiments for carrying out the invention of the present application will be described. The vertical direction is shown up and down when the smoke detector 1 is installed on the horizontal ceiling. The same applies to the horizontal direction and the vertical direction.
[0016]
　FIG. 1 is an exploded perspective view of the smoke detector 1 according to the embodiment of the present invention. The state where the smoke detector 1 is disassembled and viewed from diagonally below is shown. The smoke detector 1 is a photoelectric spot type, and captures the scattered light of the irradiation light applied to the smoke to detect the smoke. The smoke detector 1 includes a detector base 2, a first optical base cover 3, a second optical base cover 4, and a cover main body 5. In the sensor base 2, the optical base plate 7 is fixed under the back plate 6, and the circuit board 8 (see FIG. 2B) is sandwiched between the back plate 6 and the optical base plate 7. In the optical table plate 7, the optical table 71 and the plate portion 72 around the optical table 71 are integrally molded with black resin. The optical table 71 is provided with a top plate 710 on the upper side, and is provided with a peripheral wall composed of a side wall 711, a first light emitting element accommodating wall 712, a second light emitting element accommodating wall 713, a light receiving element accommodating wall 714, and the like in the horizontal direction. There is. A snap convex portion 715 is provided on the outer side of the peripheral wall, the first light emitting element accommodating wall 712, and the light receiving element accommodating wall 714. The first light emitting element 91 is housed in the first light emitting element accommodating wall 712, the second light emitting element 92 is housed in the second light emitting element accommodating wall 713, and the light receiving element 93 is housed in the light receiving element accommodating wall 714. There is. The plate portion 72 is provided with a screw hole 721 (covered by a screw 731 in FIG. 2), a translucent hole 722, and a positioning cylindrical portion 723. The light from the confirmation lamp 81 provided on the circuit board 8 is transmitted through the light transmitting hole 722.
[0017]
　The first optical table cover 3 is provided with a cover disk 31 provided horizontally, a smoke introduction fin 32 provided downward, a positioning leg 33 protruding laterally, and a snap piece 34. The center of the cover disk 31 is opened to provide a cover opening 35, and the cover disk 31 on the outside of the cover opening 35 is lowered toward the inside to form a thick thick portion 36. In the first optical base cover 3, the snap convex portion 715 is fitted to the snap piece 34 at three points in a state where the positioning leg 33 is inserted into the positioning cylindrical portion 723, and is locked to the sensor base 2.
[0018]
　The second optical base cover 4 includes a bottom portion 41 having an annular unevenness, a side vent 42 and a connecting column 43, an annular portion 44 above the bottom portion 44, and a locking piece 45 connected to the annular portion 44. The bottom portion 41 is connected to the annular portion 44 by six connecting columns 43, and the annular portion 44 is locked to the cover main body 5 via two locking pieces 45. An annular insect net (not shown) is fitted inside the vent 42 and the connecting column 43.
[0019]
　In the cover main body 5, six columns 52 are erected under the annular cover outer ring portion 51, and a protective plate 53 is connected under the six columns 52. The cover outer ring portion 51, the support column 52, and the opening 54 surrounded by the protective plate 53 are provided at six locations. Further, a confirmation light window 55 in which a transparent resin is fitted is provided in the cover outer ring portion 51. The smoke introduction fin 32 of the first optical table cover-3, the connecting column 43 of the second optical table cover 4, and the column 52 of the cover main body 5 are arranged at the same position.
[0020]
　The smoke sensing mechanism includes a lower layer of a smoke introduction unit that introduces smoke while blocking external light between the first optical table cover 3 and the second optical table cover 4, and an optical table 71 and a first smoke detection unit 10. It has a two-layer structure with an upper layer that senses smoke between the optical table covers 3. The upper layer and the lower layer are separated by the first optical table cover 3, and the upper layer and the lower layer are connected by a cover opening 35.
[0021]
　FIG. 2 is a diagram for explaining a cross section of the smoke detector 1 according to the embodiment of the present invention. 2 (a) is a view of the smoke detector 1 as viewed from below, and FIG. 2 (b) shows a cross section of FIG. 2 (a) taken along the line AA. A circuit board 8 is provided on the optical table plate 7. The circuit board 8 is provided with a circuit for detecting smoke, a circuit for communicating with the receiver (not shown), and a confirmation light 81, and the cover main body is provided through the translucent hole 722 of the plate portion 72. Lighting is confirmed from the confirmation light window 55 of No. 5 (see FIG. 1). The first optical table cover 3 is provided between the optical table plate 7 and the second optical table cover 4, and has a cover opening 35 in the center. The second optical table cover 4 has a bottom portion 41 having an annular convex portion, and a cross-protruding plate 46 projecting in a cross shape when viewed from above at the center of the bottom portion 41.
[0022]
　FIG. 2B shows a situation in which smoke enters the smoke detection unit 10 from the right side of the drawing. The arrow indicates the progress of smoke. The smoke passes through the opening 54 of the cover body 5, the vent 42 of the second optical base cover 4, and the smoke introduction portion between the first optical base cover 3 and the second optical base cover 4. Then, it is blocked by the cross protrusion plate 46, passes through the cover opening 35 of the first optical table cover 3, and reaches the smoke detection unit 10. In the smoke detection unit 10, the smoke is irradiated with the irradiation light from the first light emitting element 91 and the second light emitting element 92, and the scattered light is received by the light receiving element 93. The smoke introduction portion is provided with an annular convex portion on the upper and lower sides in order to block external light, and the smoke rises and then falls, then rises again and enters the upper layer from the cover opening 35 to reach the smoke detection portion 10.
[0023]
　The optical table plate 7, the first optical table cover 3, and the second optical table cover 4 are made of black resin. The external light is mainly blocked by the bottom 41 of the second optical table cover 4, the cover disk 31 of the first optical table cover 3, and the optical table 71 of the optical table plate 7, and does not reach the smoke detection unit 10. ..
[0024]
　FIG. 3 is a diagram for explaining forward scattering in one embodiment of the present invention. FIGS. 3 and 5 to 7 show an enlarged view from FIG. FIG. 3 is a bottom view of the optical table plate 7 to which the first light emitting element 91, the second light emitting element 92, and the light receiving element 93 are attached. In the optical table 71 of the optical table plate 7, the side wall 711 hangs down from below the top plate 710. The first light emitting element 91, the second light emitting element 92, and the light receiving element 93 are housed in the first light emitting element accommodating wall 712, the second light emitting element accommodating wall 713, and the light receiving element accommodating wall 714, respectively, and are provided on the optical table plate 7. It is connected to the circuit board 8 via a small hole. The first light emitting element accommodating wall 712, the second light emitting element accommodating wall 713, and the light receiving element accommodating wall 714 are arranged from the position of the arc-shaped side wall 711 to the inside and the outside. The part arranged inside this constitutes a part of the peripheral wall. Further, a deflection reflection wall 717 is provided from above the circumference of the substantially circumferential side wall 711 toward the outside. In the deflection reflection wall 717, a portion close to the light receiving element 93 protrudes outward, and the protruding end portion is connected to the side wall 711 by a connection wall 718. The peripheral wall of the optical table 71 is formed by the side wall 711, the first light emitting element accommodating wall 712, the second light emitting element accommodating wall 713, the light receiving element accommodating wall 714, the deflection reflection wall 717, and the connection wall 718. The side wall 711 has an arc shape, and a part thereof has a plurality of small protrusions inward. The first irradiation light, which is the irradiation light, is transmitted from the first light emitting element 91, and the second irradiation light, which is the irradiation light, is transmitted from the second light emitting element 92 toward the smoke detection unit 10. The first light emitting element accommodating wall 712 is composed of front, both sides, and rear side walls in the horizontal direction of the first light emitting element 91, and the front side wall has an opening for light transmission. Then, a part of the side wall on both sides and the front side wall form a part of the peripheral wall. The same applies to the second light emitting element accommodating wall 713 and the light receiving element accommodating wall 714. The positions of the upper surface plate 710 of the optical table 71 and the plate portion 72 in the vertical direction are the same. In the first light emitting element accommodating wall 712, the second light emitting element accommodating wall 713, and the light receiving element accommodating wall 714, the portion other than the peripheral wall has a small amount of protrusion from the plate portion 72. stomach. The length from the top plate 710 and the plate portion 72 to the lower end of the peripheral wall is constant.
[0025]
　On the light emitting side of the first light emitting element accommodating wall 712, the upper surface shading plate 719 projects downward from the upper surface plate 710. The upper light-shielding plate 719 does not reach the first optical axis 911, which is the optical axis of the first light emitting element 91. Further, the light-shielding plate 7131 protrudes from the second light emitting element accommodating wall 713. The light-shielding plate 7131 is provided with a flat surface along the direction in which the second light-emitting element 92 faces, and shields the light-shielding plate 7131 so that the first irradiation light does not directly reach the light-receiving element 93 from the first light-emitting element 91. There is.
[0026]
　The first optical axis 911, which is the optical axis of the first light emitting element 91, and the light receiving shaft 931 which is the optical axis of the light receiving element 93 intersect at an obtuse angle in the region of the smoke detection unit 10 as shown in φ1 in FIG. Therefore, when there is smoke in the smoke detection unit 10, the light receiving element 93 captures the forward scattered light of the first light emitting element 91. As for the positional relationship, the light receiving element 93 and the light receiving element 93 are located at a position where the light receiving element 93 receives the forward scattered light when the first irradiation light transmitted from the first light emitting element 91 irradiates the smoke in the smoke detecting unit 10. 1 Light emitting element 91 is arranged.
[0027]
　When there is no smoke in the smoke detection unit 10, forward scattering does not occur, but the first irradiation light is reflected a plurality of times on the inner surface of the peripheral wall of the optical table 71, and finally is received by the light receiving element 93. Therefore, a small amount of non-obstructive light reception (so-called noise) is detected. Although the optical table 71 is made of black resin, it does not completely absorb the first irradiation light and reflects a part of it. In the present application, this reflected light is used to inspect whether the first light emitting element 91 and the light receiving element 93 are functioning normally. When a failure occurs in light emission or light reception, the non-failure received light amount is not detected, so that the failure can be detected. Light emission and light reception are always performed in a normal state where there is no smoke in the smoke detection unit 10, and when such a failure occurs, it can be detected without delay.
[0028]
　FIG. 4 is a diagram showing a light emitting amount and a light receiving amount in one embodiment of the present invention. The vertical axis shows the amount of light emitted and the amount of received light, and the horizontal axis shows the time. FIG. 4A shows the amount of light emitted by the first light emitting element 91, and FIG. 4B shows the amount of light received by the light receiving element 93. As shown in FIG. 4A, the first light emitting element 91 emits light at regular time intervals. Along with this, the light receiving element 93 receives light at regular time intervals as shown in FIG. 4 (b). In FIG. 4, in the two pulses during the period shown on the left, there is no smoke in the smoke detection unit 10, no forward scattered light is generated, and the amount of light received is small as shown in FIG. 4 (b). On the other hand, in the two pulses in the period shown on the right side, there is sufficient smoke in the smoke detection unit 10, forward scattered light is generated, and the amount of received light is large. In FIG. 4B, when the amount of received light exceeds the threshold value b1, smoke is detected by the forward scattered light. Then, at the timing of light emission, when the light receiving amount is a non-obstructive light receiving amount between the threshold value b1 and the threshold value b2, it is detected that there is no smoke and that the light emitting and light receiving are not impaired. Smoke. Further, when the light receiving amount is an obstacle light receiving amount that does not reach the threshold value b2, it is detected that an obstacle has occurred.
[0029]
　By the way, the optical table 71 is black with a high light absorption rate, and as shown in FIG. 3, the first optical axis 911 of the first light emitting element 91 is deviated from the light receiving axis 931 of the light receiving element 93. Since the first irradiation light reaches the light receiving element 93 after being reflected a plurality of times on the inner surface of the optical table 71, the amount of non-obstructive light received from the first irradiation light is small. Therefore, the value of the threshold value b2 must be reduced, but in order to reduce the threshold value b2, a light receiving element 93 capable of detecting a small amount of light must be used. Therefore, in the present invention, the structure of the optical table 71 makes the amount of non-obstructive light received large within a range in which there is a difference comparable to the amount of light received when smoke is generated.
[0030]
　A structure for increasing the amount of non-obstructive light received will be described with reference to FIG. When the smoke-free smoke detection unit 10 is irradiated with the first irradiation light from the first light emitting element 91, the first irradiation light hits the side wall 711 and reflection occurs. Although the side wall 711 is black, the first irradiation light cannot be completely absorbed and is reflected. The first irradiation light spreads around the first optical axis 911, and when it reaches the side wall 711, a primary reflection region 912, which is a reflection region having a certain size, is generated as shown in FIG. The primary reflection region 912 is a region on the surface of the side wall 711, but is represented by an ellipse when viewed from the lower surface in FIG. 3 for convenience. Then, in the primary reflection region 912, reflection is performed in the direction of the primary reflection axis 913. A secondary reflector 716 is provided in the direction of the primary reflection shaft 913. The position of the secondary reflector 716 is inside the peripheral wall and is on the side of the first light emitting element 91 far from the light receiving element 93. Further, the side wall 711 behind the secondary reflector 716 is provided with a small convex portion when viewed from the light receiving element 93. The secondary reflector 716 is provided on the side far from the light receiving element accommodating wall 714 in the peripheral wall portion of the first light emitting element accommodating wall 712 protruding inward of the optical table 71. The secondary reflector 716 is provided with a surface that reflects the primary reflected light in the direction of the light receiving element 93. Therefore, the primary reflected light is reflected by the secondary reflecting plate 716 in the direction of the secondary reflecting axis 914, becomes secondary reflected light, and enters the light receiving element 93. The secondary reflector 716 increases the secondary reflected light of the first light emitting element 91, and increases the amount of non-obstructive light.
[0031]
　FIG. 5 is a diagram showing an optical table 71 according to an embodiment of the present invention. FIG. 5A shows an optical table 71 seen from below. The cross section taken along the line BB is shown in FIG. 5 (b). The BB line passes between the first light emitting element accommodating wall 712 and the second light emitting element accommodating wall 713, the upper surface shading plate 719, and the deflection reflection wall 717. In FIG. 5B, the lower part corresponds to the upper part on the ceiling side. In FIG. 5B, a short upper surface light-shielding plate 719 protrudes from the upper surface plate 710, and a secondary reflector 716 protrudes behind the upper surface light-shielding plate 719 with an amount of protrusion that is about 60% of the height of the peripheral wall such as the side wall 711. There is. The intensity of the secondary reflected light can be adjusted by appropriately setting the amount of protrusion from the upper surface side of the secondary reflector 716, but the height is preferably 30 to 90% of the peripheral wall. The upper surface shading plate 719 is located below the first optical axis 911 of the first light emitting element 91 housed in the first light emitting element accommodating wall 712, and shields the irradiation light from the first light emitting element 91 toward the upper surface plate 710. ing.
[0032]
　FIG. 6 is a view of the sensor base 2 according to the embodiment of the present invention as viewed from diagonally below. The direction is different from that of the sensor base 2 in FIG. The first light emitting element accommodating wall 712 and the second light emitting element accommodating wall 713 are provided with openings through which the irradiation light passes in the direction of the smoke detection unit 10. Although not shown in FIG. 6, the light receiving element accommodating wall 714 is also provided with an opening. A secondary reflector 716 and a top light-shielding plate 719 are provided inside the optical table 71. The upper light-shielding plate 719 is provided one by one on the smoke detection unit 10 side of the opening of the first light emitting element accommodating wall 712 and the second light emitting element accommodating wall 713.
[0033]
　A part of the primary reflected light reaches the secondary reflector 716, but the other part passes through the lower side and the side portion (right side in FIGS. 3 and 5) of the secondary reflector 716 and has a small convex portion. Is almost absorbed by. As a result, while a sufficient amount of light enters the light receiving element 93 to determine whether the first light emitting element 91 emits light, the amount of light differs from the amount of light scattered forward at the time of fire certification as a sufficiently smaller amount of light. Can be secured. Then, the SN ratio becomes large and a highly accurate smoke detector can be obtained.
[0034]
　FIG. 7 is a diagram for explaining backscatter in one embodiment of the present invention. FIG. 7 is a bottom view of the optical table plate 7 to which the first light emitting element 91, the second light emitting element 92, and the light receiving element 93 are attached as in FIG. The second optical axis 921, which is the optical axis of the second light emitting element 92, and the light receiving shaft 931 which is the optical axis of the light receiving element 93 intersect at an acute angle in the region of the smoke detection unit 10 as shown in φ2 in FIG. Therefore, the light receiving element 93 captures the backscattered light of the second irradiation light by the second light emitting element 92. As for the positional relationship, the second light emitting element 92 is located at a position where the light receiving element 93 receives the backward scattered light when the second irradiation light transmitted from the second light emitting element 92 is applied to the smoke in the smoke detecting unit 10. Is placed. As for backscattering, the light receiving element 93 receives the non-obstructive light receiving amount as in the case of forward scattering, and detects that there is no obstacle in the second light emitting element 92 and the light receiving element 93. The amount of light emitted and the amount of light received are as described for the forward scattered light in FIG. 4, and FIG. 4A shows the amount of light emitted by the second light emitting element 92. In backscattering, the second light emitting element 92 and the light receiving element 93 are oriented in substantially the same direction. Therefore, the primary reflected light of the second light emitting element 92 easily enters the light receiving element 93, and the amount of non-obstructive light received by the light receiving element 93 increases. Therefore, in FIG. 4B, the threshold value b1 at which the light receiving element 93 senses smoke and the value of the non-obstructive light amount are close to each other. Therefore, the difference in the amount of received light (SN ratio) depending on the presence or absence of smoke becomes small, and the accuracy of the smoke detector is lowered.
[0035]
　In the present invention, as shown in FIG. 7, a part of the peripheral wall of the optical table 71 is a deflection reflection wall 717. The deflection reflection wall 717 is formed so that the vertical axis of the inner surface deviates from the second optical axis 921. The deviation angle θ from the second optical axis 921 to the vertical axis is preferably 15 to 30 °, more preferably 20 to 25 °. In the present embodiment, the inner surface of the deflection reflection wall 717 is flat.
[0036]
　In FIG. 7, the second irradiation light from the second light emitting element 92 reaches the primary reflection region 922 of the deflection reflection wall 717 and is reflected. The primary reflected light generated by the reflection goes in the direction of the primary reflection axis 923 different from the direction in which the second irradiation light enters, reaches the secondary reflection region 924, and is reflected. The primary reflection region 922 and the secondary reflection region 924 are regions on the surface of the peripheral wall, and are represented by ellipses viewed from the lower surface in FIG. 7 for convenience, as in FIG. The secondary reflected light generated by the reflection is directed toward the secondary reflection axis 925 and is guided to the side of the light receiving element accommodating wall 714 opposite to the second light emitting element 92. Therefore, at least the second reflected light is not received by the light receiving element 93. Since the reflected light is absorbed by the black optical table 71 each time it is reflected, the reflected light after the third reflection becomes extremely weak, and the difference in the amount of received light (SN ratio) depending on the presence or absence of smoke can be sufficiently obtained.
[0037]
　As described above, in the present invention, fire detection and the like can be performed by the single light emission of the first light emitting element 91 and the single light emission of the second light emitting element 92 with respect to the light receiving element 93. In that case, the second light emitting element 92 and the first light emitting element 91 are unnecessary, respectively. On the other hand, smoke detection can be performed using both the first light emitting element 91 and the second light emitting element 92. The light emitted from the first light emitting element 91 and the second light emitting element 92 has different angles of scattered light entering the light receiving element 93. Then, white smoke or black smoke is determined by the ratio of the forward scattered light by the light of the first light emitting element 91 and the back scattered light by the second light emitting element 92. In the case of black smoke, since the amount of scattered light is small, the value of the forward scattered light can be amplified to determine whether or not there is a fire.
[0038]
　FIG. 8 is a diagram showing the amount of light emitted, the amount of light received by the forward scattered light, and the amount of light received by the backscattered light in one embodiment of the present invention. 8 (a) shows the light emitted by the first light emitting element 91, FIG. 8 (b) shows the light emitted by the second light emitting element 92, and FIG. 8 (c) shows the light received by the light receiving element 93. As shown in FIGS. 8A and 8B, the first light emitting element 91 and the second light emitting element 92 are out of phase with each other. The light receiving output of the light receiving element 93 distinguishes which light of the first light emitting element 91 or the second light emitting element 92 has entered, depending on the light emitting timing of each light emitting element.
[0039]
　The angle φ1 between the first optical axis 911 and the light receiving axis 931 for detecting forward scattering is an obtuse angle, but is preferably 110 to 130 °. Further, the angle φ2 between the second optical axis 921 and the light receiving shaft 931 for detecting backscatter is an acute angle, but it is preferably 50 to 70 °. In the present embodiment, the first light emitting element accommodating wall 712, the second light emitting element accommodating wall 713, and the light receiving element accommodating wall 714 are configured to surround the first light emitting element 91 and the like. It may be configured without a wall in the part. The deflection reflection wall 717 is effective depending on the angle of the inner surface in the horizontal direction, and the shape of the outer surface may be any shape. Further, the side wall 711 does not have to be arcuate.
[0040]
　If the secondary reflected light is guided toward the side surface of the light receiving element wall, the deflecting reflection wall 717 may have a loose concave inner surface. In the above, the embodiment using both the forward scattering and the backscatter is described, but it is also possible to carry out only one of them.
[0041]
　All publications, patents and patent applications cited herein are incorporated herein by reference in their entirety.
　In addition, the disclosure of Japanese patent application 2019-051478 filed on March 19, 2019, including the specification, claims and drawings, shall be incorporated herein as it is for reference.
Code description
[0042]
1 Smoke detector, 2 Sensor base, 3 1st optical base cover, 4 2nd optical base cover, 5 cover body, 6 back plate, 7 optical base plate, 8 circuit board, 10 smoke detector, 31 cover disk, 32 Smoke introduction fins, 33 legs, 34 snap pieces, 35 cover openings, 36 thick walls, 41 bottoms, 42 vents, 43 connecting columns, 44 annular parts, 45 locking pieces, 46 cross protrusions, 51 cover outer rings. Part, 52 stanchion, 53 protective plate, 54 opening, 55 confirmation light window, 71 optical stand, 72 plate part, 81 confirmation light, 91 1st light emitting element, 92 2nd light emitting element, 93 light receiving element, 710 top plate, 711 side wall, 712 first light emitting element housing wall, 713 second light emitting element housing wall, 7131 light shielding plate, 714 light receiving element housing wall, 715 snap convex part, 716 secondary reflecting plate, 717 deflection reflecting wall, 718 connection wall, 719 Top light-shielding plate, 721 screw hole, 722 translucent hole, 723 cylindrical part, 731 screw, 911 first optical axis, 912 primary reflection area, 913 primary reflection axis, 914 secondary reflection axis, 921 second optical axis, 922 primary Reflection area, 923 primary reflection axis, 924 secondary reflection area, 925 secondary reflection axis, 931 light receiving axis
The scope of the claims
[Claim 1]
　A smoke introduction unit,
　a smoke detection unit provided above the smoke introduction unit and surrounded from the side by a peripheral wall, a
　first light emitting element, and a
　light receiving element are provided, and a
　first light emitting element is transmitted from the first light emitting element. 1 The light receiving element and the first light emitting element are arranged at a position where the light receiving element receives the forward scattered light when the irradiation light is applied to the smoke in the smoke detection unit, and
　inside the peripheral wall. A secondary reflecting plate that forms a secondary reflected light when the first irradiation light is irradiated to the smoke-free unit is provided on the side of the first light emitting element, and the
　secondary reflecting plate is the first. (1) A smoke detector characterized in that the irradiation light receives and reflects the primary reflected light reflected by the peripheral wall, and the generated secondary reflected light enters the light receiving element.
[Claim 2]
　The second light emitting element is arranged at a position where the light receiving element receives the backward scattered light when the second irradiation light transmitted from the second light emitting element irradiates the smoke in the smoke detection unit, and the
　peripheral wall thereof. In the primary reflection region where the second irradiation light transmitted by the second light emitting element is reflected when the second irradiation light is irradiated to the smoke detection unit without smoke, the second irradiation light enters. The
　light receiving element is accommodated in the light receiving element accommodating wall protruding inward in the peripheral wall, and
　the second irradiation light is reflected by the deflecting reflecting wall to form the light receiving element . The smoke detector according to claim 1, wherein the smoke detector is guided to the side opposite to the second light emitting element of the element accommodating wall.
[Claim 3]
　The smoke detector according to claim 2, wherein the deflecting reflection wall is provided with a portion close to the light receiving element protruding outward.
[Claim 4]
　A claim characterized in that a light-shielding plate is provided between the first light-emitting element and the second light-emitting element, and the light-
　shielding plate is provided with a flat surface along the direction in which the second light-emitting element faces. Item 2 or 3 smoke detector.