WO2019181275A1

WO2019181275A1 - Smoke detector

Info

Publication number: WO2019181275A1
Application number: PCT/JP2019/004928
Authority: WO
Inventors: 智宏上津; 香菜大井; 橋本　裕介; 阪本　浩司
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2018-03-22
Filing date: 2019-02-13
Publication date: 2019-09-26
Also published as: TW201941170A; JP2019168830A; JP7108917B2; TWI725400B

Abstract

Provided is a smoke detector capable of suppressing an increase in stray light while improving detection accuracy. The smoke detector (1) is equipped with a detector case (7), a light-emitting element (4), a light-receiving element and a light-blocking structure (70). The detector case (7) encloses a detection space (Sp1). The light-emitting element (4) outputs light toward the detection space (Sp1). Light from the light-emitting element (4) is not directly incident on the light-receiving element, which is positioned in a location where scattered light from the smoke inside the detection space is incident. The light-blocking structure (70) projects into the detection space (Sp1) from the inner surface (700) of the detector case (7). The detector case (7) includes a wall structure (3) for passing smoke therethrough and suppressing the transmission of light therethrough. The light-blocking structure (70) is positioned along the path of light which is outputted from the light-emitting element (4), is reflected one or more times by the inner surface (700) of the detector case (7), and is incident on the light-receiving element.

Description

smoke detector

The present disclosure relates generally to smoke detectors, and more specifically, includes a light emitting element and a light receiving element, and detects light by receiving light output from the light emitting element scattered by the smoke flowing into the sensing space by the light receiving element. It relates to smoke detectors.

Conventionally, a smoke detector that detects smoke by irradiating the smoke that has entered the sensing space (smoke sensing area) with light from the light emitting element (light emitting element) and receiving the scattered light from the smoke with the light receiving element. Known (for example, Patent Document 1).

The smoke detector described in Patent Document 1 enables inflow of smoke from a smoke inflow path formed by a gap between labyrinth walls into a sensing area in a sensing space surrounded by a plurality of labyrinth walls. In addition, the labyrinth wall has an external light blocking action so that external light does not enter through the smoke inflow path so that the smoke sensing function is not unstable due to light from the outside. In Patent Document 1, the smoke detector that houses the light emitting element and the light receiving element is substantially circular. Further, in Patent Document 1, the rear part of the light emitting element and the light receiving element (that is, the end part opposite to the sensing space) is protruded to form a wide sensing space.

JP 2010-40009

In the configuration described in Patent Document 1, for example, one of the light output from the light emitting element on the inner surface of the sensing case due to contamination of the sensing case (smoke detector) surrounding the sensing space, intrusion of foreign matter, and the like. Part may be reflected toward the light receiving element. As a result, not only light scattered by smoke in the sensing space but also reflected light from the inner surface of the sensing case may enter the light receiving element, and stray light may increase.

The present disclosure has been made in view of the above reasons, and an object thereof is to provide a smoke detector capable of suppressing an increase in stray light while improving detection accuracy.

The smoke detector according to one aspect of the present disclosure includes a detection case, a light emitting element, a light receiving element, and a light shielding structure. The sensing case surrounds a sensing space. The light emitting element outputs light toward the sensing space. The light receiving element is disposed at a position where direct light from the light emitting element is not incident and light scattered by smoke in the sensing space is incident. The light shielding structure protrudes from the inner surface of the sensing case into the sensing space. The sensing case includes a wall structure that allows the smoke to pass therethrough and suppresses light transmission. The light shielding structure is positioned on a path of light output from the light emitting element and reflected once or more on the inner surface of the sensing case and incident on the light receiving element.

FIG. 1 is a partially broken perspective view of a detection block of a smoke detector according to the first embodiment. FIG. 2A is an external perspective view of the smoke detector as seen from obliquely below. FIG. 2B is an external perspective view of the smoke detector as seen from obliquely above. FIG. 3 is an exploded perspective view of the smoke detector as seen from obliquely below. FIG. 4 is an exploded perspective view of the above smoke detector as viewed obliquely from above. FIG. 5 is a partially broken perspective view of the smoke detector. FIG. 6 is an exploded perspective view of a sensing block in the smoke detector. FIG. 7 is a plan view of the sensing block in a state where the second case of the smoke detector is removed. FIG. 8A is a plan view of the sensing block in a state where the second case of the smoke detector is removed. FIG. 8B shows an essential part of the smoke detector of the same, and is an enlarged view of a region Z1 in FIG. 8A. FIG. 9 shows an essential part of the smoke detector of the same, and is an enlarged cross-sectional view of a region Z1 in FIG. FIG. 10 is a sectional view taken along line A1-A1 of FIG. FIG. 11A is a plan view of the main part of the sensing block in a state where the second case of the smoke detector is removed. FIG. 11B is an end view showing a main part of the smoke detector. FIG. 12 is a plan view of the sensing block in a state in which the second case of the smoke detector according to the second embodiment is removed. FIG. 13 is a plan view of the sensing block in a state where the second case of the smoke detector according to the modification of the second embodiment is removed. FIG. 14A is a plan view of the sensing block in a state in which the second case of the smoke detector according to the third embodiment is removed. FIG. 14B is an enlarged view of the region Z1 in FIG. 14A. FIG. 15A is a plan view of a sensing block in a state where a second case of the smoke detector according to the second embodiment is removed. FIG. 15B is an enlarged view of a region Z1 in FIG. 15A. FIG. 16 is a plan view of the sensing block in a state where the second case of the smoke detector according to the fourth embodiment is removed.

(Embodiment 1)
(1) Outline The smoke detector according to the present embodiment is a disaster prevention device that issues a notification when smoke generated by a fire or the like is detected. That is, when smoke is generated in the event of a disaster such as a fire, the smoke detector detects the smoke and, for example, issues a warning by outputting an alarm sound or interlocking with other devices by a communication function. The “disaster prevention device” as used in the present disclosure is a device that is installed in a facility for the purpose of, for example, preventing disasters such as fire, preventing the spread of damage caused by disasters, or recovering from disasters.

As shown in FIGS. 2A and 2B, the smoke detector 1 includes a housing 2 and accommodates various components in the housing 2. The smoke detector 1 is installed and used in a facility. In the present embodiment, the case where the smoke detector 1 is used in a non-residential facility such as a hotel, office building, school, welfare facility, commercial facility, theme park, hospital or factory is exemplified. Not limited to this, the smoke detector 1 may be used in a facility such as an apartment house or a detached house. The smoke detector 1 is installed in a facility in a state of being attached to a ceiling, a wall, or the like, for example, in a room, hallway or stairs of the facility.

As shown in FIG. 1, the smoke detector 1 according to the present embodiment includes a sensing case 7, a light emitting element 4, a light receiving element 5, and a light shielding structure 70. The sensing case 7 surrounds the sensing space Sp1. The light emitting element 4 outputs light toward the sensing space Sp1. The light receiving element 5 is arranged at a position where the direct light from the light emitting element 4 does not enter and the scattered light from the smoke in the sensing space Sp1 enters. Thus, in a state where no smoke exists in the sensing space Sp1, the light receiving element 5 does not receive light output from the light emitting element 4, and in a state where smoke exists in the sensing space Sp1, the light receiving element 5 The light (scattered light) output from 4 and scattered by smoke is received. Therefore, the smoke detector 1 can detect the smoke present in the sensing space Sp 1 depending on the light receiving state of the light receiving element 5. The sensing case 7 includes a wall structure 3 that allows smoke to pass and suppresses light transmission. That is, the wall structure 3 has a function of taking smoke into the sensing space Sp1 from the outside of the sensing space Sp1, while suppressing light from entering the sensing space Sp1 from the outside of the sensing space Sp1.

Here, the light shielding structure 70 protrudes from the inner surface 700 of the sensing case 7 into the sensing space Sp1. The light shielding structure 70 is positioned on the light paths Op1, Op2, Op3 (see FIGS. 11A and 11B) of the light output from the light emitting element 4 and reflected one or more times by the inner surface 700 of the sensing case 7 and entering the light receiving element 5. To do.

According to this configuration, at least part of the light output from the light emitting element 4 and reflected by the inner surface 700 of the sensing case 7 at least once and incident on the light receiving element 5 is blocked by the light blocking structure 70. Therefore, in the smoke detector 1 according to the present embodiment, light output from the light emitting element 4 may be reflected by the inner surface 700 of the sensing case 7 and enter the light receiving element 5 as compared with a configuration without the light shielding structure 70. Can be reduced. Therefore, for example, even when the sensing case 7 surrounding the sensing space Sp1 is contaminated or a foreign substance enters, a part of the light output from the light emitting element 4 is transmitted to the light receiving element 5 on the inner surface 700 of the sensing case 7. The possibility of being reflected back is reduced. As a result, it is difficult for light reflected from the inner surface 700 of the sensing case 7 to enter the light receiving element 5, and an increase in stray light can be suppressed while improving the sensing accuracy of the smoke detector 1.

(2) Configuration Hereinafter, the configuration of the smoke detector 1 according to the present embodiment will be described in detail.

In the present embodiment, as an example, the smoke detector 1 will be described as being attached to the ceiling of a facility. Hereinafter, in the state in which the smoke detector 1 is attached to the ceiling, a direction perpendicular (orthogonal) to the horizontal plane is referred to as “up and down direction”, and a lower direction in the up and down direction is referred to as “down direction”. The arrow indicating the “vertical direction” in the drawing is merely shown for the sake of explanation, and is not accompanied by an entity. However, these directions are not intended to limit the use direction (mounting direction) of the smoke detector 1. For example, the “downward” defined here may be the front (horizontal direction) in the actual installation state of the smoke detector 1.

In each drawing described below, the configuration of the smoke detector 1 is schematically shown, and various dimensional relationships in the drawing may differ from the actual product.

(2.1) Overall Configuration First, the overall configuration of the smoke detector 1 according to the present embodiment will be described with reference to FIGS. 2A to 5.

The smoke detector 1 includes a housing 2, a detection block 10 (see FIG. 3), and a circuit block 20 (see FIG. 3). In the present embodiment, the smoke detector 1 further includes a sound output unit 61 (see FIG. 3) and a battery 62. The battery 62 is not necessarily included in the components of the smoke detector 1, and the battery 62 may not be included in the components of the smoke detector 1.

The housing 2 has a disk shape that is circular in plan view. The housing 2 is a molded product made of synthetic resin. The housing 2 has a first cover 21 and a second cover 22. The first cover 21 is combined with the second cover 22 so as to cover the lower surface of the second cover 22. The second cover 22 is fixed to a construction surface (a ceiling surface in the present embodiment). However, strictly speaking, the second cover 22 is not directly fixed to the construction surface, but is indirectly fixed to the construction surface by being fixed to the mounting base fixed to the construction surface. The

Here, both the first cover 21 and the second cover 22 are formed in a disc shape, and the outer peripheral shape in plan view is the same. Therefore, the first cover 21 and the second cover 22 are combined to form one disk-shaped housing 2. The first cover 21 is coupled to the second cover 22 by a plurality of (three) screws 63. In a state where the first cover 21 and the second cover 22 are coupled to each other, the sensing block 10, the circuit block 20, and the sound output unit 61 are accommodated between the first cover 21 and the second cover 22.

The first cover 21 has a circular first main plate 211 and a first peripheral wall 212 protruding upward from the outer peripheral portion of the upper surface of the first main plate 211. The first cover 21 has a circuit region 213 (see FIG. 4) for arranging the circuit block 20 and a first acoustic region 214 (see FIG. 4) for arranging the sound output unit 61 on the upper surface of the first main plate 211. 4). The first cover 21 further has a push button 215 arranged in the circuit area 213. The push button 215 is configured to be movable by a hinge structure with respect to the first main plate 211, and can be pushed into the inside of the housing 2, that is, upward. When the push button 215 is pushed, a switch included in the circuit block 20 arranged in the circuit area 213 is operated.

Further, a groove 216 (see FIG. 2A) extending along the outer peripheral edge is formed on the lower surface of the first main plate 211. The groove 216 is substantially concentric with the outer peripheral edge of the lower surface of the first main plate 211 and is formed over the entire circumference. That is, the groove 216 has an annular shape that is slightly smaller than the outer peripheral edge of the lower surface of the first main plate 211. Furthermore, a sound hole 217 (see FIG. 2A) that penetrates the first main plate 211 in the thickness direction of the first main plate 211 is formed in a portion of the bottom surface of the groove 216 corresponding to the first acoustic region 214. .

The second cover 22 has a circular second main plate 221 and a second peripheral wall 222 protruding upward from the outer peripheral portion of the upper surface of the second main plate 221. The second cover 22 further includes an accommodation area 223 (see FIG. 3) for arranging the sensing block 10 and a second acoustic area 224 for arranging the sound output unit 61 on the lower surface of the second main plate 221. Have. The second cover 22 further has a battery region 225 (see FIG. 4) for housing the battery 62 on the upper surface of the second main plate 221.

The second cover 22 further includes a plurality of spacers 226 that protrude downward from the lower surface of the second main plate 221. The plurality of spacers 226 ensure a predetermined gap between the first cover 21 and the second cover 22 by bringing the respective leading end portions (lower end portions) into contact with the upper surface of the first main plate 211. Specifically, in the state where the first cover 21 and the second cover 22 are coupled to each other, the internal space of the housing 2 is defined between the upper end surface of the first peripheral wall 212 and the lower surface of the second main plate 221. A gap is formed as an opening 23 connected to the outside of the housing 2. Thereby, smoke can flow into the internal space of the housing 2, that is, the space between the first cover 21 and the second cover 22 through the opening 23.

The sensing block 10 includes a sensing case 7, a light emitting element 4 (see FIG. 6), and a light receiving element 5 (see FIG. 6). The sensing case 7 has a disk shape that is circular in plan view. The sensing case 7 is a molded product made of synthetic resin. Here, the sensing case 7 has at least light shielding properties. In this embodiment, a part of the sensing case 7 functions as the wall structure 3 (see FIG. 5). The wall structure 3 has a function of taking smoke into the sensing space Sp1 from the outside of the sensing space Sp1, while suppressing light from entering the sensing space Sp1 from the outside of the sensing space Sp1. The sensing block 10 is disposed above the circuit block 20 in the internal space of the housing 2. The sensing block 10 senses smoke present in the sensing space Sp1 (see FIG. 5) in the sensing case 7.

That is, as shown in FIG. 5, the sensing block 10 is housed together with the circuit block 20 and the like in the internal space of the housing 2, that is, the space between the first cover 21 and the second cover 22. Since the internal space of the housing 2 is connected to the outside of the housing 2 through the opening 23 as described above, smoke can flow into the internal space of the housing 2 through the opening 23. In FIG. 5, a part of the smoke entry path is schematically indicated by a dotted arrow. And since the sensing block 10 has the wall structure 3 which takes in smoke into the sensing space Sp1 from the outside of the sensing space Sp1, the smoke that has flowed into the internal space of the housing 2 can further flow into the sensing space Sp1. Thereby, the sensing block 10 can sense smoke. Details of the sensing block 10 will be described in the section “(2.2) Configuration of sensing block”.

The circuit block 20 includes a printed wiring board 201 and a plurality of electronic components 202 including switches. The plurality of electronic components 202 are mounted on the printed wiring board 201. The light emitting element 4 and the light receiving element 5 of the sensing block 10 are electrically connected to the conductor portion of the printed wiring board 201. Further, the sound output unit 61 and the battery 62 are further electrically connected to the conductor portion of the printed wiring board 201. In the present embodiment, the printed wiring board 201 is disposed below the sensing block 10, that is, between the sensing block 10 and the first main board 211. The sensing block 10 is mounted on one surface (upper surface) of the printed wiring board 201 in the thickness direction.

Here, the circuit block 20 includes a control circuit composed of a plurality of electronic components 202. The control circuit is a circuit that controls the light emitting element 4, the light receiving element 5, the sound output unit 61, and the like, drives at least the light emitting element 4, and executes signal processing on the output signal of the light receiving element 5. In the signal processing, the circuit block 20 determines the presence or absence of smoke in the sensing space Sp1 by comparing the amount of light received by the light receiving element 5 (the magnitude of the output signal) with a threshold value. The amount of light received by the light receiving element 5 varies depending on, for example, the concentration of smoke in the sensing space Sp1 and the type of smoke (white smoke, black smoke, etc.). Therefore, the circuit block 20 determines that “smoke is present” when smoke having a certain concentration or more is present in the sensing space Sp1 by comparison with the threshold value. When detecting the presence of smoke, the circuit block 20 outputs an electrical signal for driving the sound output unit 61 to the sound output unit 61.

The sound output unit 61 receives the electric signal from the circuit block 20 and outputs sound (sound wave). The sound output unit 61 is realized by a speaker or a buzzer that converts an electrical signal into sound. The sound output unit 61 has a disk shape that is circular in plan view.

The battery 62 is accommodated in the battery region 225 above the second cover 22. The battery 62 may be either a primary battery or a secondary battery.

The smoke detector 1 according to the present embodiment configured as described above is included in, for example, a component of an automatic fire alarm system. In addition to the smoke detector 1, the automatic fire alarm system, for example, a receiver that receives an alarm signal (fire signal) from the smoke detector 1, and a button for operating a push button when a person detects a fire. Equipped with a transmitter. In the automatic fire alarm system, for example, when the smoke detector 1 detects the occurrence of a fire (due to smoke), a notification signal (fire signal) is sent from the smoke detector 1 to the receiver to notify the fire occurrence. Is done.

(2.2) Configuration of Sensing Block Next, a more detailed configuration of the sensing block 10 will be described with reference to FIGS. However, each drawing described below is a schematic diagram, and the length or size ratio of each part in the drawing does not necessarily reflect the actual dimensional ratio.

The sensing block 10 includes the sensing case 7, the light emitting element 4, and the light receiving element 5 as described above, and a part of the sensing case 7 functions as the wall structure 3. A sensing space Sp1 is formed inside the sensing case 7. The sensing case 7 includes a light emitting element holder 8 that holds the light emitting element 4. Further, the sensing case 7 has a light receiving element holder 9 that holds the light receiving element 5. That is, the smoke detector 1 according to the present embodiment includes a light emitting element holder 8 and a light receiving element holder 9.

In the present embodiment, as shown in FIG. 6, the sensing case 7 has a first case 71 and a second case 72. The second case 72 is combined with the first case 71 so as to cover the upper surface of the first case 71. The first case 71 is fixed to the printed wiring board 201 (see FIG. 3). The first case 71 has a pair of claws 711 (see FIG. 7) for fixing the first case 71 to the printed wiring board 201. The pair of claws 711 protrude downward from the outer peripheral portion of the lower surface of the first case 71, and the first case 71 is fixed to the printed wiring board 201 by being caught on the periphery of the hole of the printed wiring board 201. In other words, the first case 71 is mechanically coupled to the printed wiring board 201 by a snap-fit method.

Here, both the first case 71 and the second case 72 are formed in a circular shape in plan view, and the outer peripheral shape in plan view is substantially the same. For this reason, the first case 71 and the second case 72 are combined to form one disc-shaped sensing case 7. The first case 71 has a pair of claws 712 (see FIG. 7) for joining the first case 71 and the second case 72 together. The pair of claws 712 protrude upward from the outer peripheral portion of the upper surface of the first case 71, and are hooked on the outer peripheral surface of the second case 72, thereby connecting the first case 71 and the second case 72. In other words, the first case 71 and the second case 72 are mechanically coupled by a snap fit method. A sensing space Sp1 is formed between the first case 71 and the second case 72 in a state where the first case 71 and the second case 72 are coupled to each other.

The first case 71 has a circular bottom plate 73 and a wall structure 3 protruding upward from the outer peripheral portion of the (first) inner bottom surface 731 which is the upper surface of the bottom plate 73. The inner bottom surface 731 of the bottom plate 73 constitutes the bottom surface of the sensing space Sp1. The first case 71 further includes a first holder 81 that constitutes a part of the light emitting element holder 8 and a light receiving element holder 9. The first case 71 further includes a light shielding wall 74 (see FIG. 7), a light shielding rib 75 (see FIG. 7), and an auxiliary light shielding wall 76 (see FIG. 7) which will be described later. Each of the first holder 81, the light receiving element holder 9, the light shielding wall 74, the light shielding rib 75, and the auxiliary light shielding wall 76 protrudes upward from the inner bottom surface 731 of the bottom plate 73. Here, the protruding amount of the light emitting element holder 8, the light receiving element holder 9, the light shielding wall 74, and the auxiliary light shielding wall 76 from the inner bottom surface 731 of the bottom plate 73 is substantially the same as the protruding amount of the wall structure 3 from the inner bottom surface 731 of the bottom plate 73. Are the same.

The second case 72 has a circular upper plate 721 and a peripheral wall 722 that protrudes downward from the outer peripheral portion of the (second) inner bottom surface 725 that is the lower surface of the upper plate 721. The inner diameter of the peripheral wall 722 is larger than the outer diameter of the wall structure 3. Further, the protruding amount of the peripheral wall 722 from the inner bottom surface 725 of the upper plate 721 is substantially the same as the protruding amount of the wall structure 3 from the inner bottom surface 731 of the bottom plate 73. Therefore, in a state where the first case 71 and the second case 72 are coupled to each other, the distal end surface (lower end surface) of the peripheral wall 722 contacts the inner bottom surface 731 of the bottom plate 73, and the distal end surface (upper end surface) of the wall structure 3. Contacts the inner bottom surface 725 of the upper plate 721. In this state, the wall structure 3 is accommodated in a space surrounded by the peripheral wall 722.

The peripheral wall 722 is formed with a plurality of window holes 723 that penetrate the peripheral wall 722 in the thickness direction of the peripheral wall 722. The plurality of window holes 723 are arranged along the circumferential direction of the inner bottom surface 725 of the upper plate 721. Accordingly, the wall structure 3 is exposed to the outside of the sensing case 7 through the plurality of window holes 723 in a state where the first case 71 and the second case 72 are coupled to each other. Here, an insect net may be attached to the peripheral wall 722 so as to cover the plurality of window holes 723. The insect net reduces the entry of foreign matters such as insects from the plurality of window holes 723 into the sensing space Sp1 in the sensing case 7.

The second case 72 further has a second holder 82 (see FIG. 9) that constitutes a part of the light emitting element holder 8. The second holder 82 constitutes the light emitting element holder 8 together with the first holder 81. In other words, the light emitting element holder 8 is divided into two members: a first holder 81 provided in the first case 71 and a second holder 82 provided in the second case 72. Further, the second case 72 has a light shielding rib 724 as a “second light shielding rib” at a position facing the light shielding rib 75 as the “first light shielding rib” in the inner bottom surface 725 of the upper plate 721 (see FIG. 9). It has further.

The (first) light shielding rib 75 and the (second) light shielding rib 724 are included in the light shielding structure 70 protruding from the inner surface 700 (see FIG. 1) of the sensing case 7 into the sensing space Sp1. That is, the light shielding rib 75 and the light shielding rib 724 constitute at least a part of the light shielding structure 70. Details of the light shielding structure 70 will be described in the section “(2.3) Configuration of light shielding structure”.

As shown in FIG. 8A, the wall structure 3 surrounds the sensing space Sp1 when viewed from one direction (above) orthogonal to the inner bottom surface 731 (one plane) of the bottom plate 73. FIG. 8A is a plan view of the sensing block 10 with the second case 72 removed, that is, with the second case 72 omitted. In the present embodiment, a circular sensing space Sp 1 is formed on the inner bottom surface 731 of the bottom plate 73 in a plan view. The wall structure 3 is formed in an annular shape so as to surround the sensing space Sp1 in the plan view. In other words, an annular wall structure 3 is formed on the outer peripheral portion of the inner bottom surface 731 of the bottom plate 73 along the outer peripheral edge of the inner bottom surface 731. In a state where the first case 71 and the second case 72 are coupled to each other, the space between the bottom plate 73 and the upper plate 721 and surrounded by the wall structure 3 becomes the sensing space Sp1. That is, the sensing space Sp1 and the space around the sensing space Sp1 are partitioned by the wall structure 3.

Here, the wall structure 3 has an inner surface 31 facing the sensing space Sp1 side and an outer surface 32 facing the opposite side to the sensing space Sp1 on both sides in the thickness direction of the wall structure 3. The wall structure 3 allows smoke to pass and suppresses light transmission in the thickness direction. That is, the wall structure 3 is a structure having a predetermined thickness in plan view, and has an inner surface 31 and an outer surface 32 on both sides in the thickness direction. In the present embodiment, the wall structure 3 has the radial direction of the inner bottom surface 731 of the bottom plate 73, that is, the direction along the inner bottom surface 731 (one plane) of the bottom plate 73 and the center of the sensing space Sp1 from the periphery of the sensing space Sp1. The direction toward is the thickness direction of the wall structure 3. The wall structure 3 has a function of suppressing light transmission while allowing smoke to pass between the inner side surface 31 and the outer side surface 32. Thereby, the wall structure 3 makes it possible to take in smoke into the sensing space Sp1 from the outside of the sensing space Sp1, while suppressing light from entering the sensing space Sp1 from the outside of the sensing space Sp1. In the present embodiment, the thickness of the wall structure 3 is substantially uniform over the entire circumference, and the outer peripheral edge of the inner bottom surface 731, the inner side surface 31, and the outer side surface 32 are substantially concentric in a plan view.

Such a wall structure 3 has a plurality of smoke passage holes 33 penetrating the wall structure 3 in the thickness direction, that is, passing between the inner side surface 31 and the outer side surface 32 in order to realize the above function. ing. The plurality of smoke passage holes 33 are arranged along the circumferential direction of the wall structure 3. Thereby, the wall structure 3 can let smoke pass through each smoke passage hole 33, and enables the smoke to be taken into the sensing space Sp1 from the outside of the sensing space Sp1. Here, each smoke passage hole 33 is not shaped to penetrate straightly between the inner side surface 31 and the outer side surface 32 in a plan view, but at least a part between the inner side surface 31 and the outer side surface 32 is bent. Shape. That is, at least a part of each smoke passage hole 33 is arranged so that the sensing space Sp1 surrounded by the wall structure 3 cannot be seen through the smoke passage holes 33 from the outer surface 32 side of the wall structure 3. It has a curved or bent shape. As a result, the wall structure 3 is inhibited from transmitting light through the wall structure 3 through each smoke passage hole 33, and light can be prevented from entering the sensing space Sp1 from the outside of the sensing space Sp1. However, the smoke passage hole 33 does not have to be surrounded by the wall structure 3 on its entire circumference. For example, the wall structure 3 may not exist on both sides of the smoke passage hole 33 in the vertical direction. Further, the opening on the inner side surface 31 side and the opening on the outer side surface 32 side of each smoke passage hole 33 are on the radius of the sensing space Sp1, that is, on a straight line extending radially from the center point P1 of the sensing space Sp1 in plan view. It does not have to be in line.

Specifically, the wall structure 3 is an aggregate of a plurality of small pieces 30 arranged along the inner surface 31. The wall structure 3 allows smoke to pass between the plurality of small pieces 30. In other words, on the outer peripheral portion of the inner bottom surface 731 of the bottom plate 73, a plurality of small pieces 30 are arranged side by side along the outer peripheral edge of the inner bottom surface 731. Each of the plurality of small pieces 30 protrudes from the inner bottom surface 731 of the bottom plate 73 and constitutes one wall structure 3. The amount of protrusion from the inner bottom surface 731 of the plurality of small pieces 30 is substantially uniform. The wall structure 3 has smoke passing holes 33 between a pair of adjacent small pieces 30 among the plurality of small pieces 30. Therefore, the small pieces 30 constituting the wall structure 3 do not exist on both sides of each smoke passage hole 33 in the vertical direction.

The inner side surface 31 is a surface that passes through the edge 301 on the sensing space Sp1 side of the plurality of small pieces 30. The outer side surface 32 is a surface that passes through the edge 302 opposite to the sensing space Sp1 of the plurality of small pieces 30. In short, the inner surface 31 corresponds to a smooth curved surface, a plane, or a combination of a plane and a curved surface connecting the edges 301 on the sensing space Sp1 side of the plurality of small pieces 30. Similarly, a smooth curved surface, a plane, or a combination of a plane and a curved surface connecting the edges 302 of the plurality of small pieces 30 on the side opposite to the sensing space Sp 1 corresponds to the outer surface 32.

In other words, the edge 301 on the sensing space Sp1 side of the plurality of small pieces 30 is located on the inner surface 31, and the edge 302 opposite to the sensing space Sp1 of the plurality of small pieces 30 is located on the outer surface 32. Among the plurality of small pieces 30, also in the small piece 30 that is continuous with the auxiliary light shielding wall 76 described later, like the other small pieces 30, the edge 301 on the sensing space Sp 1 side is located on the inner side surface 31, and the plurality of small pieces 30. An edge 302 opposite to the sensing space Sp 1 is located on the outer surface 32. Thus, in this embodiment, each of the inner surface 31 and the outer surface 32 is not an imaginary surface but a virtual surface whose shape is defined by the plurality of small pieces 30. Therefore, in FIG. 8A and FIG. 8B, the inner side surface 31 and the outer side surface 32 are described with an imaginary line (two-dot chain line). In FIG. 8A, the area corresponding to the wall structure 3 is shaded (dot hatched).

However, it is not essential that the position of the edge 301 is completely coincident with the inner side surface 31 for all of the plurality of small pieces 30. If the position of the edge 301 is substantially coincident with the inner side surface 31 for the plurality of small pieces 30. Good. In the example of FIG. 8A as well, the majority of the small pieces 30 among the plurality of small pieces 30 have the position of the edge 301 on the sensing space Sp1 side completely coincided with the inner surface 31, but the remaining small pieces 30 have the edge 301. Is located near the inner side surface 31, but does not completely coincide with the inner side surface 31. As described above, the inner side surface 31 is defined by the position of the edge 301 of the majority of the small pieces 30 among the plurality of small pieces 30, and for the remaining small pieces 30, the edge 301 may be in the vicinity of the inner side 31. The same applies to the outer side surface 32, and it is not essential that the position of the edge 302 is completely coincident with the outer surface 32 for all of the plurality of small pieces 30, and the position of the edge 302 is the outer surface for the plurality of small pieces 30. It is only necessary to substantially match 32. That is, the outer surface 32 is defined by the position of the edge 302 of the majority of the small pieces 30 among the plurality of small pieces 30, and for the remaining small pieces 30, the edge 302 may be in the vicinity of the outer surface 32. The “near” here is a range of about 20% of the thickness of the wall structure 3 when viewed from the inner surface 31 or the outer surface 32.

In the present embodiment, the outer surface 32 is substantially parallel to the outer peripheral edge of the inner bottom surface 731 of the bottom plate 73 in a plan view, that is, the distance from the outer peripheral edge of the inner bottom surface 731 to the outer surface 32 is uniform over the entire periphery. Further, as shown in FIG. 8A, the inner side surface 31 is formed between the center point P1 and the outer side surface 32 of the sensing space Sp1 and closer to the outer side surface 32 than the center point P1. In other words, in a plan view, when a virtual circle that is a substantially concentric circle of the outer surface 32 and has a radius half (1/2) of the outer surface 32 is drawn, the virtual circle and the outer surface 32 are The inner side surface 31 is located. However, the shapes and arrangements of the inner side surface 31 and the outer side surface 32 are merely examples, and the inner side surface 31 and the outer side surface 32 may adopt other shapes and arrangements.

Here, each of the plurality of small pieces 30 has a bent portion between the edge 301 on the sensing space Sp1 side and the edge 302 on the opposite side to the sensing space Sp1 in plan view. In the present embodiment, each of the plurality of small pieces 30 is formed in a substantially L shape, a substantially V shape, or a substantially Y shape in plan view. With such a shape, each smoke passage hole 33 formed of a gap formed between a pair of adjacent small pieces 30 has at least a part between the inner side surface 31 and the outer side surface 32 in plan view as described above. It becomes a bent shape. Thereby, the wall structure 3 implement | achieves the function which lets smoke pass and suppresses permeation | transmission of light in the thickness direction.

The light emitting element 4 has a light emitting surface 41 (see FIG. 7), and outputs light from the light emitting surface 41 when energized. In the present embodiment, as an example, the light emitting element 4 is a light emitting diode (LED: Light Emitting Diode). The light emitting element 4 has a main body 401 as shown in FIG. A pair of lead terminals 402 protrudes from the surface of the main body 401. Here, the pair of lead terminals 402 is electrically connected to the main body 401 of the light emitting element 4. When the pair of lead terminals 402 are electrically connected to the printed wiring board 201, the light emitting element 4 emits light upon receiving power supply from the circuit block 20. In the present embodiment, the pair of lead terminals 402 is described as not included in the constituent elements of the light emitting element 4, but the pair of lead terminals 402 may be included in the constituent elements of the light emitting element 4.

Here, as shown in FIG. 8A, the light emitting element 4 is disposed between the inner side surface 31 and the outer side surface 32 of the wall structure 3. In other words, the main body portion 401 of the light emitting element 4 is disposed so as to fit between the inner side surface 31 and the outer side surface 32 which are both end surfaces in the thickness direction of the wall structure 3. In addition, the light emitting element 4 is arranged with the light emitting surface 41 facing the inner surface 31 side, that is, the sensing space Sp1 side. Thereby, the light emitting element 4 can output light from the light emitting surface 41 toward the sensing space Sp1 without using an optical element such as a mirror.

In the present embodiment, as shown in FIG. 9, the light emitting element 4 further includes a back surface 42 facing the outer surface 32 side, and a bottom surface 43 connecting the light emitting surface 41 and the back surface 42. FIG. 9 is an enlarged cross-sectional view of the region Z1 in FIG. A pair of lead wires electrically connected to the light emitting element 4 protrudes from the bottom surface 43. In the present embodiment, the lead wire protruding from the bottom surface 43 is the lead terminal 402. In other words, the light emitting element 4 has the light emitting surface 41 and the back surface 42 on both sides in the thickness direction of the wall structure 3 in the main body 401. The lead terminal 402 protrudes from the bottom surface 43 adjacent to both the light emitting surface 41 and the back surface 42 instead of the light emitting surface 41 and the back surface 42. That is, the light emitting element 4 is a so-called side view type light emitting diode that outputs light to the side when the surface (bottom surface 43) from which the lead terminal 402 protrudes is directed downward.

In the present embodiment, the lead wire (lead terminal 402) protrudes from the light emitting element 4 in a direction (here, downward) perpendicular to the optical axis Ax1 (see FIG. 10) of the light emitting element 4. That is, the lead terminal 402 protrudes downward from the bottom surface 43 as described above, and the lead terminal 402 can be drawn downward from the light emitting element 4 without adopting a bending structure for a part of the lead terminal 402. Is possible.

In the light emitting element 4 having such a structure, the thickness of the wall structure 3 is larger than that of a light emitting element having a lead terminal protruding from a surface opposite to the light emitting surface, such as a so-called bullet-type light emitting diode. The occupied space in the direction can be reduced. That is, in the side-view type light emitting diode, the lead terminal 402 protruding from the bottom surface 43 is drawn out from the light emitting element 4 with the light emitting surface 41 facing the inner side surface 31 in a direction perpendicular to the thickness direction of the wall structure 3. be able to. As a result, the light emitting surface 41 is placed on the inner surface 31 side between the inner surface 31 and the outer surface 32 of the wall structure 3 as described above, while keeping the thickness direction dimension of the wall structure 3 relatively small. It is possible to arrange the light emitting element 4 so as to face it.

Here, the bottom surface 43 is along the inner bottom surface 731 (one plane) of the bottom plate 73. In the present embodiment, the bottom surface 43 is not parallel to the inner bottom surface 731 of the bottom plate 73 but is inclined with respect to the inner bottom surface 731. However, the bottom surface 43 only needs to be along the inner bottom surface 731 of the bottom plate 73, and may be substantially parallel to the inner bottom surface 731.

More specifically, the light exit surface 41 includes a flat portion 411 and a convex portion 412. The flat portion 411 is a plane substantially parallel to the back surface 42. The convex part 412 projects in a dome shape from the flat part 411 and functions as a convex lens. As shown in FIG. 9, the main body unit 401 includes a light emitting unit 403 and a lead unit 404. The light emitting unit 403 is mounted on the surface of the lead unit 404 facing the outer surface 32 side, and emits light when energized. The lead portion 404 is configured integrally with the lead terminal 402.

The light receiving element 5 is an element that performs photoelectric conversion for converting light into an electrical signal. In the present embodiment, as an example, the light receiving element 5 is a photodiode (PD). As illustrated in FIG. 6, the light receiving element 5 includes a main body portion 501, a pair of lead terminals 502, and a metal cover 503. The main body 501 is accommodated in the metal cover 503 so that at least the light receiving surface of the main body 501 is exposed from the hole of the metal cover 503. The pair of lead terminals 502 protrude from the lower surface of the main body 501. Here, the pair of lead terminals 502 is electrically connected to the main body 501 of the light receiving element 5. The light receiving element 5 is electrically connected to the circuit block 20 by electrically connecting the pair of lead terminals 502 to the printed wiring board 201.

Here, the light receiving element 5 is arranged at a position where the direct light from the light emitting element 4 does not enter and the scattered light from the smoke in the sensing space Sp1 enters. Specifically, the light receiving element 5 is disposed with the light receiving surface of the main body 501 facing the sensing space Sp1. That is, both the light emitting element 4 and the light receiving element 5 are arranged toward the sensing space Sp1. However, as shown in FIG. 7, a light shielding wall 74 is arranged on a straight line connecting the light emitting element 4 and the light receiving element 5 in plan view. The light blocking wall 74 has a function of blocking direct light from the light emitting element 4 to the light receiving element 5. In the present embodiment, the light shielding wall 74 is formed in a shape that is continuous with one of the plurality of small pieces 30 constituting the wall structure 3. FIG. 7 is a plan view of the sensing block 10 with the second case 72 removed, that is, with the second case 72 omitted.

8A, the light emitting element 4 and the light receiving element 5 are arranged in a positional relationship such that the optical axis Ax1 of the light emitting element 4 and the optical axis Ax2 of the light receiving element 5 intersect each other in plan view. Has been. In the example of FIG. 8A, the optical axis Ax1 of the light emitting element 4 and the optical axis Ax2 of the light receiving element 5 intersect at the center point P1 of the circular sensing space Sp1 in plan view. If the light emitting element 4 and the light receiving element 5 are in the positional relationship as described above, direct light from the light emitting element 4 does not enter the light receiving element 5. On the other hand, when smoke flows into the sensing space Sp1, the light from the light emitting element 4 is scattered by the smoke present at the center point P1 of the sensing space Sp1, and at least a part of this scattered light is received by the light receiving element 5. Is done.

As described above, in a state where no smoke exists in the sensing space Sp1, the light receiving element 5 does not receive light output from the light emitting element 4, and in a state where smoke exists in the sensing space Sp1, the light receiving element 5 emits light. Light output from the element 4 and scattered by smoke (scattered light) is received. Therefore, the smoke detector 1 can detect the smoke present in the sensing space Sp 1 depending on the light receiving state of the light receiving element 5.

Here, in the present embodiment, since the light emitting element 4 is within the thickness of the wall structure 3 as described above, the sensing space Sp1 is compared with the configuration in which the light emitting element 4 protrudes from the inner surface 31 of the wall structure 3. Can be secured widely. If the sensing space Sp1 is widened, the degree of freedom of arrangement of the light shielding walls 74 in the sensing space Sp1 is increased. Furthermore, if the sensing space Sp1 becomes wider, the light shielding wall 74 can be disposed at a position relatively distant from the center point P1 of the sensing space Sp1.

In the present embodiment, the optical axis Ax1 of the light emitting element 4 and the optical axis Ax2 of the light receiving element 5 are along the inner bottom surface 731 (one plane) of the bottom plate 73, as shown in FIG. FIG. 10 is an end view taken along line A1-A1 of FIG. In the example of FIG. 10, the optical axis Ax1 of the light emitting element 4 and the optical axis Ax2 of the light receiving element 5 are both substantially parallel to the inner bottom surface 731 of the bottom plate 73. Further, the optical axis Ax1 of the light emitting element 4 and the optical axis Ax2 of the light receiving element 5 are located in the same plane. In other words, the optical axis Ax1 of the light emitting element 4 and the optical axis Ax2 of the light receiving element 5 are at substantially the same height from the inner bottom surface 731 of the bottom plate 73.

Further, the light shielding rib 75 is disposed in front of the light emitting element 4, that is, at a position facing the light emitting surface 41 of the light emitting element 4 in plan view. As shown in FIG. 9, a certain gap is generated between the light shielding rib 75 and the light shielding rib 724 provided on the second case 72. The optical axis Ax1 of the light emitting element 4 passes through the gap between the light shielding rib 75 and the light shielding rib 724. As a result, the light shielding rib 75 and the light shielding rib 724 prevent the light output from the light emitting element 4 from spreading in the vertical direction. As a result, the light output from the light emitting element 4 is suppressed from being reflected on the upper surface (inner bottom surface 731) of the bottom plate 73 or the lower surface (inner bottom surface 725) of the upper plate 721.

The auxiliary light shielding wall 76 is formed in a shape that is continuous with one small piece 30 located between the light shielding wall 74 and the light receiving element holder 9 among the plurality of small pieces 30 constituting the wall structure 3. The auxiliary light shielding wall 76 protrudes from the inner surface 31 of the wall structure 3 into the sensing space Sp1. The auxiliary light shielding wall 76 suppresses the generation of stray light inside the sensing space Sp1 due to the reflection of light at the inner bottom surface 731 of the bottom plate 73 or the inner bottom surface 725 of the upper plate 721, and enters the sensing space Sp1. Has the function of improving the inflow of smoke. That is, the auxiliary light shielding wall 76 is a separate structure from the small piece 30 that is a part of the wall structure 3 for suppressing light from entering the sensing space Sp1 from the outside of the sensing space Sp1. In FIG. 7, the boundary line between the auxiliary light shielding wall 76 and the small piece 30 is indicated by an imaginary line (two-dot chain line).

The light emitting element holder 8 is divided into two members, the first holder 81 provided in the first case 71 and the second holder 82 provided in the second case 72 as described above. Hold. Here, at least a part of the light emitting element holder 8 is disposed between the inner side surface 31 and the outer side surface 32 as shown in FIG. 8A. Specifically, the first holder 81 is disposed between the plurality of small pieces 30 constituting the wall structure 3 so that most of the first holder 81 is accommodated between the inner side surface 31 and the outer side surface 32. The first holder 81 has a recess in which the light emitting element 4 is fitted.

Furthermore, in the present embodiment, the light emitting element holder 8 is disposed so as to fit in the region surrounded by the outer surface 32. That is, the light emitting element holder 8 (including the first holder 81) is formed in a shape that does not protrude from the outer surface 32 and fits in a region surrounded by the outer surface 32.

The light emitting element holder 8 has a through hole 801 for passing a lead wire electrically connected to the light emitting element 4. In the present embodiment, the lead wire passing through the through hole 801 is the lead terminal 402. The through hole 801 is formed in the first holder 81. Here, the through hole 801 is formed between the inner side surface 31 and the outer side surface 32 and closer to the outer side surface 32 than the inner side surface 31, as shown in FIG. 8B. In other words, as shown in FIG. 8A, when a center line C1 that bisects the wall structure 3 in the thickness direction is drawn in a plan view, a through hole is formed between the center line C1 and the outer surface 32. 801 will be located.

The light emitting element holder 8 further includes a light shielding piece 802 as shown in FIG. The light shielding piece 802 protrudes into the sensing space Sp1 from the surface of the first holder 81 facing the sensing space Sp1 side. Here, the light shielding piece 802 protrudes from the end of the first holder 81 on the side farther from the light shielding wall 74 in the circumferential direction of the wall structure 3. The light shielding piece 802 has a function of shielding light output from the light emitting element 4 and reflected by the surface of the light emitting element holder 8.

The light shielding piece 802 is included in the light shielding structure 70 protruding from the inner surface 700 (see FIG. 1) of the sensing case 7 into the sensing space Sp1. That is, in the present embodiment, the light shielding piece 802 constitutes at least a part of the light shielding structure 70 together with the light shielding rib 75 and the light shielding rib 724. Details of the light shielding structure 70 will be described in the section “(2.3) Configuration of light shielding structure”.

The light emitting element holder 8 further has a positioning surface 803 as shown in FIG. The positioning surface 803 is a surface that intersects the optical axis Ax1 of the light emitting element 4, and positions the light emitting element 4 by contacting the light emitting element 4 from the outer surface 32 side. That is, the positioning surface 803 contacts the back surface 42 of the light emitting element 4 and positions the light emitting element 4 in the thickness direction of the wall structure 3. In the present embodiment, since the light emitting element holder 8 is divided into the two members of the first holder 81 and the second holder 82 as described above, the first holder 81 and the first holder 81 are also disposed on the positioning surface 803. The two holders 82 are formed over two members.

Furthermore, in this embodiment, the positioning surface 803 has elasticity, that is, springiness. The positioning surface 803 applies an elastic force to the light emitting element 4 so as to push the light emitting element 4 from the outer surface 32 side. In the present embodiment, since the light emitting element holder 8 is made of synthetic resin, at least the second holder 82 functions as a resin spring, so that the positioning surface 803 is given the elasticity described above.

The light receiving element holder 9 holds the light receiving element 5. Here, at least a part of the light receiving element holder 9 is disposed between the inner side surface 31 and the outer side surface 32 as shown in FIG. 8A. Specifically, the light receiving element holder 9 is disposed between the plurality of small pieces 30 constituting the wall structure 3 so that most of the light receiving element holder 9 is accommodated between the inner side surface 31 and the outer side surface 32. The light receiving element holder 9 has a recess in which the light receiving element 5 is fitted.

(2.3) Configuration of Light Shielding Structure Next, a more detailed configuration of the light shielding structure 70 will be described with reference to FIGS. 1, 11A, and 11B. In FIG. 11A and FIG. 11B, a part of the path | route (optical path) of the light output from the light emitting element 4 is typically shown with the dotted-line arrow. However, each drawing described below is a schematic diagram, and the length or size ratio of each part in the drawing does not necessarily reflect the actual dimensional ratio.

The smoke detector 1 according to the present embodiment has the light shielding structure 70 protruding from the inner surface 700 of the sensing case 7 into the sensing space Sp1 as described above. The “inner surface 700 of the sensing case 7” in the present disclosure is a surface that is the inner side of the sensing case 7 and faces the sensing space Sp1 side as the inner space of the sensing case 7. In the present embodiment, the inner side surface 31 of the wall structure 3, the inner bottom surface 731 of the first case 71 (upper surface of the bottom plate 73), and the inner bottom surface 725 of the second case 72 (lower surface of the upper plate 721) It is included in the inner surface 700. Further, the surface of the light emitting element holder 8 and the light receiving element holder 9 facing the sensing space Sp1 side is also included in the inner surface 700 of the sensing case 7.

The smoke detector 1 according to the present embodiment includes the light shielding piece 802, the light shielding rib 75, and the light shielding rib 724 as the light shielding structure 70 as described above. That is, the light shielding piece 802, the light shielding rib 75, and the light shielding rib 724 all protrude from the inner surface 700 of the sensing case 7 into the sensing space Sp1. The light shielding pieces 802, the light shielding ribs 75, and the light shielding ribs 724 are light paths Op 1, Op 2, Op 3 (light output from the light emitting element 4 and reflected one or more times at the inner surface 700 of the sensing case 7 and incident on the light receiving element 5. 11A and 11B).

By providing such a light shielding structure 70, the smoke detector 1 reflects at least part of the light output from the light emitting element 4 and reflected by the inner surface 700 of the sensing case 7 at least once and incident on the light receiving element 5. It can be blocked by the light blocking structure 70. In other words, it is difficult to uniformly control the light reflection direction on the inner surface 700 of the sensing case 7, and it is greatly changed due to contamination of the sensing case 7 surrounding the sensing space Sp1 and intrusion of foreign matter. . Therefore, when such reflected light from the inner surface 700 of the sensing case 7 enters the light receiving element 5, it affects the amount of light received by the light receiving element 5 (the magnitude of the output signal), and consequently the detection result of the smoke detector 1. Will have an impact. In short, the light output from the light emitting element 4 and reflected at least once by the inner surface 700 of the sensing case 7 becomes so-called “stray light” and becomes a factor that lowers the sensing accuracy of the smoke detector 1. The smoke detector 1 according to the present embodiment can suppress an increase in stray light while improving the detection accuracy by blocking at least a part of the stray light as described above by the light blocking structure 70.

More specifically, in the present embodiment, the sensing case 7 has a light emitting element holder 8 for holding the light emitting element 4 as shown in FIG. The light shielding structure 70 includes a light shielding piece 802 protruding from the light emitting element holder 8. The light shielding piece 802 projects into the sensing space Sp1 from the surface of the light emitting element holder 8 facing the sensing space Sp1 side. Here, an exit 804 through which light from the light emitting element 4 in the light emitting element holder 8 is emitted is formed on the surface of the light emitting element holder 8 facing the sensing space Sp1 side. The light shielding piece 802 is positioned around the emission port 804 in the light emitting element holder 8. Here, the light shielding piece 802 is not provided on the entire circumference of the emission port 804 but is provided only on one side of the emission port 804 in plan view. Specifically, the light shielding piece 802 is disposed at a position opposite to the light shielding wall 74 in the circumferential direction of the wall structure 3 when viewed from the emission port 804. In short, the light shielding piece 802 is formed asymmetrically with respect to the optical axis Ax1 of the light emitting element 4 in plan view (see FIG. 11A). Since the light shielding piece 802 is asymmetric, light rays that can be a stray light component are easily shielded by the light shielding piece 802, and light rays that are scattered by smoke in the sensing space Sp1 and reach the light receiving element 5 are shielded by the light shielding piece 802. It becomes difficult structure. Therefore, according to the light shielding piece 802 having such a configuration, it is possible to suppress an increase in stray light while improving the sensing accuracy.

Further, the light shielding piece 802 is formed integrally with the first holder 81 provided in the first case 71, and is formed in a triangular shape in which the tip end side becomes thinner in plan view. Further, the light shielding piece 802 is formed over substantially the entire width in the vertical direction of the sensing space Sp1. That is, in the sensing space Sp1, the light shielding pieces 802 are formed between the pair of inner bottom surfaces 731 and 725 located on both sides in the vertical direction of the sensing space Sp1.

As shown in FIG. 11A, the light shielding piece 802 having the configuration described above is output from the light emitting element 4, reflected by the surface of the light emitting element holder 8, and reflected by the inner surface 700 of the sensing case 7 at least once to receive light. It is located on the path Op 1 of light incident on the element 5. That is, at least part of the light output from the light emitting element 4 and reflected by the inner surface 700 of the sensing case 7 at least once and incident on the light receiving element 5 is blocked by the light shielding piece 802 that is the light shielding structure 70. .

If there is no light shielding piece 802, the light passing through the path Op1 is reflected by the inner side surface 31 of the wall structure 3 included in the inner surface 700 of the sensing case 7, and may enter the light receiving element 5 in some cases. In the smoke detector 1 according to the present embodiment, since the light shielding piece 802 is positioned on the path Op1, the light passing through the path Op1 can be blocked by the light shielding piece 802, and the generation of “stray light” is suppressed. Is possible. However, the inner side surface 31 of the wall structure 3 included in the inner surface 700 of the sensing case 7 is not an actual surface but a virtual surface whose shape is defined by a plurality of small pieces 30. Strictly speaking, the reflection of light occurs on the surfaces of the plurality of small pieces 30.

In a plan view, a light path may be generated at a position symmetrical to the path Op1 with respect to the optical axis Ax1 of the light emitting element 4. However, since the light on such a path is output from the emission port 804 toward the light shielding wall 74 (see FIG. 7), the light is blocked by the light shielding wall 74 and is not likely to be stray light. Therefore, even in the configuration in which the light shielding piece 802 is provided only on one side of the emission port 804 in plan view as in the present embodiment, it is sufficient to suppress the occurrence of “stray light” in the light shielding piece 802. Is possible.

Further, as shown in FIG. 1, the sensing case 7 has a pair of inner bottom surfaces 731 and 725 facing each other in the vertical direction (one direction) as a part of the inner surface 700. The light shielding structure 70 includes

light shielding ribs

75 and 724 protruding from at least one of the pair of inner bottom surfaces 731 and 725. In the present embodiment, the

light shielding ribs

75 and 724 protrude from each of the pair of inner bottom surfaces 731 and 725. That is, the light shielding structure 70 protrudes upward from the inner bottom surface 731 of the first case 71 (first) light shielding rib 75, and projects downward from the inner bottom surface 725 of the second case 72 (second) light shielding rib 724. , Including.

Here, the light-shielding rib 75 and the light-shielding rib 724 are formed so as to abut each other on the tip surfaces. A certain gap is secured between the

light shielding ribs

75 and 724. The optical axis Ax1 of the light emitting element 4 passes through the gap between the light shielding rib 75 and the light shielding rib 724, as shown in FIG. 11B. As a result, the light shielding rib 75 and the light shielding rib 724 prevent the light output from the light emitting element 4 from spreading in the vertical direction.

In other words, the

light shielding ribs

75 and 724 are positioned on the light paths Op2 and Op3 of light output from the light emitting element 4 and incident on at least one of the pair of inner bottom surfaces 731 and 725. In the present embodiment, the light shielding rib 75 disposed below the optical axis Ax1 of the light emitting element 4 is located on the path Op2 of light output from the light emitting element 4 and incident on the inner bottom surface 731. The light shielding rib 724 disposed above the optical axis Ax1 of the light emitting element 4 is positioned on the path Op2 of light output from the light emitting element 4 and incident on the inner bottom surface 725.

Further, the

light shielding ribs

75 and 724 are disposed at positions overlapping the optical axis Ax1 of the light emitting element 4 in plan view (see FIG. 11A). Specifically, the light shielding rib 75 and the light shielding rib 724 are both disposed in front of the light emitting element 4 in plan view. Although only the light shielding rib 75 is shown in FIG. 11A, the position and shape of the light shielding rib 724 in plan view are the same as those of the light shielding rib 75.

Furthermore, the

light shielding ribs

75 and 724 have a shape extending in a direction intersecting the optical axis Ax1 of the light emitting element 4. Specifically, both the light shielding rib 75 and the light shielding rib 724 are formed in a flat plate shape orthogonal to the optical axis Ax1 of the light emitting element 4. Thereby, light incident on the light shielding rib 75 or the light shielding rib 724 out of the light output from the light emitting element 4 is transmitted along the optical axis Ax1 of the light emitting element 4 by the light shielding rib 75 or the light shielding rib 724. It becomes easy to be reflected to the 4 side. Therefore, it is difficult for light incident on the light shielding rib 75 or the light shielding rib 724 to diffuse in the sensing space Sp1.

Here, as shown in FIG. 11A, in the plan view, the projection amount L1 of the

light shielding ribs

75 and 724 from the optical axis Ax1 of the light emitting element 4 to the light shielding wall 74 side is from the optical axis Ax1 of the light emitting element 4 to the light shielding wall 74. Is smaller than the protruding amount L2 of the

light shielding ribs

75 and 724 to the opposite side (L1 <L2). Specifically, the

light shielding ribs

75 and 724 are disposed at positions on the opposite side to the light shielding wall 74 in the circumferential direction of the wall structure 3 when viewed from the optical axis Ax1 of the light emitting element 4. In short, the

light shielding ribs

75 and 724 are formed asymmetrically with respect to the optical axis Ax1 of the light emitting element 4 in plan view.

As shown in FIG. 11B, the

light shielding ribs

75 and 724 having the above-described configuration are paths of light Op2 output from the light emitting element 4, reflected by the inner surface 700 of the sensing case 7 at least once, and incident on the light receiving element 5. , Op3. That is, at least a part of the light output from the light emitting element 4 and reflected by the inner surface 700 of the sensing case 7 at least once and incident on the light receiving element 5 is blocked by the

light shielding ribs

75 and 724 that are the light shielding structure 70. become.

If the

light shielding ribs

75 and 724 are not provided, the light passing through the paths Op2 and Op3 is reflected by the pair of inner bottom surfaces 731 and 725 included in the inner surface 700 of the sensing case 7, and depending on the case, the light receiving element 5 may be reflected. Incident. In the smoke detector 1 according to the present embodiment, since the light shielding rib 75 is positioned on the path Op2, the light passing through the path Op2 can be blocked by the light shielding rib 75, and the generation of “stray light” is suppressed. Is possible. Similarly, with respect to the route Op3, the light shielding rib 724 is positioned on the route Op3, so that light passing through the route Op3 can be blocked by the light shielding rib 724, and generation of “stray light” can be suppressed.

In plan view, the light may be output from the light exit 804 toward the light shielding wall 74 (see FIG. 7). However, such light is blocked by the light shielding wall 74 and is unlikely to be stray light. Therefore, as in the present embodiment, even in a configuration in which the

light shielding ribs

75 and 724 are provided at positions close to the light shielding wall 74 when viewed from the optical axis Ax1 of the light emitting element 4 in plan view, It is sufficiently possible to suppress the generation of “stray light” by the

light shielding ribs

75 and 724.

(3) Modification The smoke detector 1 according to the first embodiment is only one of various embodiments of the present disclosure. The smoke detector 1 according to the first embodiment can be variously changed depending on the design or the like as long as the object of the present disclosure can be achieved. Hereinafter, modifications of the first embodiment will be listed. The modifications described below can be applied in appropriate combinations.

In Embodiment 1, the wall structure 3 is composed of an assembly of a plurality of small pieces 30. However, the present invention is not limited to this configuration, and the wall structure 3 may be an integral “wall” that is continuous in the circumferential direction. Even in this case, the wall structure 3 has a plurality of smoke passage holes 33 penetrating the wall structure 3 in the thickness direction, thereby realizing a function of allowing smoke to pass in the thickness direction and suppressing light transmission. is there.

In the first embodiment, the configuration in which the sensing block 10 is accommodated in the internal space of the housing 2 is described. However, the configuration is not limited to this configuration. For example, at least a part of the sensing block 10 protrudes from the housing 2. It may be. Furthermore, the housing | casing 2 is not an essential structure for the smoke detector 1, and can be abbreviate | omitted suitably.

In the first embodiment, the case where both the sensing case 7 and the sensing space Sp1 are circular in plan view has been described. However, the present invention is not limited to this configuration, and the sensing case 7 or the sensing space Sp1 is, for example, in plan view. May be oval or polygonal. In this case, the wall structure 3 also has an elliptical shape or a polygonal shape in plan view.

In the first embodiment, a part of the light emitting element holder 8 is arranged so as to protrude from the inner side surface 31 of the wall structure 3 into the sensing space Sp1, but not limited to this configuration, the entire light emitting element holder 8 is also provided. May be accommodated between the inner surface 31 and the outer surface 32. Similarly, the light receiving element holder 9 may be located between the inner side surface 31 and the outer side surface 32.

In the first embodiment, the plurality of small pieces 30 are formed integrally with the bottom plate 73 so as to protrude from the inner bottom surface 731 of the bottom plate 73. However, the present invention is not limited to this configuration, and the plurality of small pieces 30 are separated from the bottom plate 73. It may be a body. For example, the plurality of small pieces 30 may be fixed to the bottom plate 73 by adhesion or fitting. In this case, the plurality of small pieces 30 exist separately, but even in this case, the plurality of small pieces 30 constitute one wall structure 3.

The light-emitting element 4 is not limited to a light-emitting diode, and may be, for example, an organic EL (Electro-Luminescence) element or a laser diode (LD). The light receiving element 5 is not limited to a photodiode, and may be a phototransistor, for example.

The lead wire protruding from the bottom surface 43 or the lead wire passing through the through hole 801 of the light emitting element holder 8 may be a lead wire electrically connected to the light emitting element 4, and is not limited to the lead terminal 402. For example, an electric wire or the like electrically connected to the lead terminal 402 may be used.

Further, the pair of lead terminals 402 is not limited to the configuration protruding from the bottom surface 43, and may protrude from a surface other than the bottom surface 43 in the main body 401, such as the light emitting surface 41 or the back surface 42.

The light shielding structure 70 may be positioned on the path of light output from the light emitting element 4 and reflected at the inner surface 700 of the sensing case 7 one or more times and incident on the light receiving element 5. Then, it may be positioned on the path of light incident on the light receiving element 5.

Further, the light shielding structure 70 is not limited to a structure that completely blocks light, but may be any structure that reduces the amount of light transmitted through the light shielding structure 70.

Further, it is not essential for the smoke detector 1 that the light shielding structure 70 includes both the light shielding piece 802 and the

light shielding ribs

75 and 724. For example, the light shielding piece 802 or the

light shielding ribs

75 and 724 may be omitted. . Further, even when the light shielding structure 70 includes a light shielding rib, the light shielding structure 70 only needs to have the

light shielding ribs

75 and 724 protruding from at least one of the pair of inner bottom surfaces 731 and 725. Only one of them may be omitted.

Further, the shape of each of the

light shielding ribs

75 and 724 is not limited to a flat plate shape orthogonal to the optical axis Ax1 of the light emitting element 4, and may be, for example, a curved plate shape or a polygonal column shape. Further, the light shielding rib 75 and the light shielding rib 724 may have different positions and shapes in plan view.

(Embodiment 2)
As shown in FIG. 12, the smoke detector 1A according to the present embodiment is different from the smoke detector 1 according to the first embodiment in the shape of the wall structure 3 and the like. Hereinafter, the same configurations as those of the first embodiment are denoted by common reference numerals, and description thereof is omitted as appropriate.

In the smoke detector 1A, as shown in FIG. 12, there is almost no space between the outer peripheral edge of the inner bottom surface 731 of the bottom plate 73 of the first case 71 and the outer surface 32 of the wall structure 3 in plan view. In the present embodiment, the auxiliary light shielding wall 76 (see FIG. 7) is omitted. Further, the shape of each of the plurality of small pieces 30 constituting the wall structure 3 is also different from the smoke detector 1 according to the first embodiment. FIG. 12 is a plan view of the sensing block 10 with the second case 72 removed, that is, with the second case 72 omitted. In FIG. 12, the inner side surface 31 and the outer side surface 32 are indicated by imaginary lines (two-dot chain lines), and the area corresponding to the wall structure 3 is shaded (dot hatched).

In addition, the smoke detector 1A is different from the smoke detector 1 according to the first embodiment in the external shape of the light emitting element 4. However, also in this embodiment, the light emitting element 4 is a so-called side view type light emitting diode that outputs light to the side when the surface (bottom surface 43) from which the lead terminal 402 protrudes is directed downward. The light emitting element 4 is arranged between the inner side surface 31 and the outer side surface 32 of the wall structure 3 with the light emitting surface 41 facing the inner side surface 31 side.

FIG. 13 shows a smoke detector 1B according to a modification of the second embodiment. In the smoke detector 1 B shown in FIG. 13, the wall structure 3 is provided not in the first case 71 but in the second case 72. FIG. 13 is a plan view of the sensing block 10 with the second case 72 removed, that is, with the second case 72 omitted. Therefore, in FIG. 13, the wall structure 3 is indicated by an imaginary line (two-dot chain line). In FIG. 13, the inner side surface 31 and the outer side surface 32 are represented by imaginary lines (two-dot chain lines), and the area corresponding to the wall structure 3 is shaded (dot hatched). Furthermore, in the example of FIG. 13, the light shielding wall 74 is also provided in the second case 72 together with the wall structure 3. Also in the smoke detector 1B having such a configuration, in a state where the first case 71 and the second case 72 are coupled to each other, like the smoke detector 1A, the wall so as to surround the detection space Sp1 in a plan view. Structure 3 will be placed.

The configuration of the second embodiment (including modifications) can be applied in appropriate combination with the configuration described in the first embodiment (including modifications).

(Embodiment 3)
As shown in FIGS. 14A and 14B, the smoke detector 1C according to the present embodiment is different from the smoke detector 1A according to the second embodiment in the shape of each of the plurality of small pieces 30 constituting the wall structure 3. In FIG. 14A and FIG. 14B, a part of the light beam output from the light emitting element 4 is typically shown with a dotted line. FIG. 14B is an enlarged view of a region Z1 in FIG. 14A. Hereinafter, the same configurations as those of the second embodiment are denoted by common reference numerals, and the description thereof is omitted as appropriate.

In the present embodiment, as shown in FIG. 14A, at least a part of the plurality of small pieces 30 includes a concave curved surface 303 on a surface facing the sensing space Sp1, that is, a surface on which direct light from the light emitting element 4 is incident. It is out. Here, among the plurality of small pieces 30, only the small piece 30 at a position where the direct light from the light emitting element 4 enters, that is, the small piece 30 positioned substantially in front of the light emitting element 4 has the concave curved surface 303. The concave curved surface 303 is curved so as to be, for example, a part of a parabola or a part of an ellipse in plan view.

Incidentally, FIGS. 15A and 15B are plan views schematically showing a part of the light beam output from the light emitting element 4 with respect to the smoke detector 1A according to the second embodiment. As is clear from FIGS. 15A and 15B, when the small piece 30 does not have the concave curved surface 303, when a part of the light output from the light emitting element 4 enters one of the small pieces 30, the light is incident on the small piece 30. May be reflected. The light reflected by one of the small pieces 30 is reflected toward the small piece 30 adjacent to the small piece 30 as shown in FIG. 15B. At this time, the small piece 30 reflects the light incident on the small piece 30 as substantially parallel light as it is substantially parallel light. As a result, as shown in a path Op4 in FIGS. 15A and 15B, a part of the light is reflected by a plurality of small pieces 30 and incident on the light receiving element 5 as so-called “stray light”. This is a factor that lowers the detection accuracy.

On the other hand, according to the smoke detector 1 C according to the present embodiment, when a part of the light output from the light emitting element 4 enters one of the small pieces 30, this light enters the concave curved surface 303 of the small piece 30. And reflected. The light reflected by the concave curved surface 303 of any of the small pieces 30 is reflected toward the small pieces 30 adjacent to the small pieces 30 as shown in FIG. 14B. At this time, the concave curved surface 303 acts to collect light incident on the concave curved surface 303 as substantially parallel light. As a result, the light from the light emitting element 4 incident on the small piece 30 can be confined between a pair of adjacent small pieces 30, and the “stray light” incident on the light receiving element 5 is reduced as compared with the example of FIGS. 15A and 15B. Can be reduced. Therefore, in the smoke detector 1C according to the present embodiment, an increase in stray light can be suppressed while improving the detection accuracy.

As a modified example of the third embodiment, at least a part of the plurality of small pieces 30 is different from the (first) concave curved surface 303 on the back surface of the concave curved surface 303, that is, the surface facing the opposite side of the concave curved surface 303 ( 2) It may have a concave curved surface. In this configuration, the light reflected by the first concave curved surface 303 is further condensed by the second concave curved surface, and the light from the light emitting element 4 incident on the small piece 30 is easily confined between a pair of adjacent small pieces 30. Therefore, “stray light” incident on the light receiving element 5 can be further reduced, and an increase in stray light can be suppressed while improving detection accuracy.

The configuration of the third embodiment (including modifications) can be applied in appropriate combination with the configuration (including modifications) described in the first and second embodiments.

(Embodiment 4)
As shown in FIG. 16, the smoke detector 1D according to the present embodiment is different from the smoke detector 1 according to the first embodiment in that the light shielding wall 74 includes a plurality of

small walls

741 and 742. In FIG. 16, the light irradiation area A 1 by the light emitting element 4 and the light receiving area A 2 by the light receiving element 5 are shaded (dot hatching). A region where the irradiation region A1 and the light receiving region A2 overlap is a sensing region A3 that contributes to smoke detection, particularly in the sensing space Sp1. Moreover, in FIG. 16, the single light shielding wall 74 in Embodiment 1 is shown with an imaginary line (two-dot chain line). Hereinafter, the same configurations as those of the first embodiment are denoted by common reference numerals, and description thereof is omitted as appropriate.

In the present embodiment, the light shielding wall 74 has two

small walls

741 and 742, a (first) small wall 741 and a (second) small wall 742. That is, a plurality of

small walls

741 and 742 constituting the light shielding wall 74 are arranged on a straight line connecting the light emitting element 4 and the light receiving element 5 in plan view. The plurality of

small walls

741 and 742 have a function of blocking direct light from the light emitting element 4 to the light receiving element 5.

Specifically, the small wall 741 is disposed closer to the light emitting element 4 than the single light shielding wall 74 in the first embodiment in plan view. Thereby, the small wall 741 mainly functions to shield a part of the light output from the light emitting element 4 and narrow the irradiation area A1. On the other hand, the small wall 742 is disposed closer to the light receiving element 5 than the single light shielding wall 74 in the first embodiment in plan view. Thereby, the small wall 742 functions to shield part of light incident on the light receiving element 5 and narrow the light receiving region A2.

According to the smoke detector 1D according to the present embodiment, the light shielding wall 74 (small) from the center point P1 of the sensing space Sp1 where the optical axis Ax1 of the light emitting element 4 and the optical axis Ax2 of the light receiving element 5 intersect in plan view. A relatively large distance to the walls 741, 742) can be secured. That is, as compared with the single light shielding wall 74 in the first embodiment, each of the plurality of

small walls

741 and 742 can be arranged at a position away from the center point P1. Thereby, the freedom degree of arrangement | positioning of the light-shielding wall 74 in sensing space Sp1 becomes high.

As a modification of the fourth embodiment, the light shielding wall 74 may have three or more small walls.

The configuration of the fourth embodiment (including modifications) can be applied in appropriate combination with the configuration (including modifications) described in the first to third embodiments.

(Summary)
As described above, the smoke detectors (1, 1A to 1D) according to the first aspect include the sensing case (7), the light emitting element (4), the light receiving element (5), and the light shielding structure (70). And comprising. The sensing case (7) surrounds the sensing space (Sp1). The light emitting element (4) outputs light toward the sensing space (Sp1). The light receiving element (5) is arranged at a position where the direct light from the light emitting element (4) does not enter and the scattered light from the smoke in the sensing space (Sp1) enters. The light shielding structure (70) protrudes from the inner surface (700) of the sensing case (7) into the sensing space (Sp1). The sensing case (7) includes a wall structure (3) that allows smoke to pass and suppresses light transmission. The light shielding structure (70) is a light path (Op1, Op2, Op3) that is output from the light emitting element (4) and reflected one or more times at the inner surface (700) of the sensing case (7) to enter the light receiving element (5). ) Located on top.

According to this aspect, at least part of the light output from the light emitting element (4) and reflected by the inner surface (700) of the sensing case (7) at least once and incident on the light receiving element (5) has a light shielding structure ( 70). Therefore, compared with the configuration without the light shielding structure (70), the light output from the light emitting element (4) is reflected by the inner surface (700) of the sensing case (7) and may enter the light receiving element (5). Can be reduced. Therefore, for example, even when the sensing case (7) is contaminated or a foreign substance enters, a part of the light output from the light emitting element (4) is received by the inner surface (700) of the sensing case (7). The possibility of reflection towards the element (5) is reduced. As a result, it becomes difficult for light reflected from the inner surface (700) of the sensing case (7) to enter the light receiving element (5), and while improving the detection accuracy of the smoke detectors (1, 1A to 1D). It is possible to suppress an increase in stray light.

In the smoke detectors (1, 1A to 1D) according to the second aspect, in the first aspect, the detection case (7) has a light emitting element holder (8) for holding the light emitting element (4). The light shielding structure (70) includes a light shielding piece (802) protruding from the light emitting element holder (8).

According to this aspect, the light shielding piece (802) which is at least a part of the light shielding structure (70) can be disposed in the vicinity of the light emitting element (4), and the light shielding structure (70) can be downsized. .

In the smoke detector (1, 1A to 1D) according to the third aspect, in the second aspect, the light shielding piece (802) emits light from the light emitting element (4) in the light emitting element holder (8). It is located around the exit (804).

According to this aspect, the light shielding piece (802), which is at least a part of the light shielding structure (70), can be disposed closer to the light emitting element (4), thereby further reducing the size of the light shielding structure (70). Can be planned.

In the smoke detector (1, 1A to 1D) according to the fourth aspect, in any one of the first to third aspects, the half-value angle (θ1) of the light emitting element (4) is 25 degrees or more.

According to this aspect, since the light emitting element (4) is a relatively wide-angle element, a relatively wide area of the sensing space (Sp1) can be covered with the light emitting element (4), and the smoke detectors (1, 1A to 1D). It is possible to improve the accuracy of sensing.

In the smoke detectors (1, 1A to 1D) according to the fifth aspect, in any one of the first to fourth aspects, the wall structure (3) is perpendicular to one plane (the inner bottom surface 731 of the bottom plate 73). The sensing space (Sp1) is enclosed as seen from the direction. The sensing case (7) has a pair of inner bottom surfaces (731, 725) facing each other in one direction. The light shielding structure (70) includes light shielding ribs (75, 724) protruding from at least one of the pair of inner bottom surfaces (731, 725).

According to this aspect, it is possible to suppress the spread of light output from the light emitting element (4) in one direction orthogonal to one plane (the inner bottom surface 731 of the bottom plate 73).

In the smoke detectors (1, 1A to 1D) according to the sixth aspect, in the fifth aspect, the light shielding ribs (75, 724) are output from the light emitting element (4) and are paired with the inner bottom surfaces (731, 725). Are located on a path (Op2, Op3) of light incident on at least one of the two.

According to this aspect, the detection accuracy of the smoke detectors (1, 1A to 1D) is reduced due to light output from the light emitting element (4) and reflected by at least one of the pair of inner bottom surfaces (731, 725). Can be suppressed.

In the smoke detectors (1, 1A to 1D) according to the seventh aspect, in the fifth or sixth aspect, the light shielding ribs (75, 724) are in one direction orthogonal to one plane (the inner bottom surface 731 of the bottom plate 73). When viewed from the side, it is arranged at a position overlapping the optical axis (Ax1) of the light emitting element (4).

According to this aspect, the light from the light emitting element (4) is easily blocked by the light blocking rib (75, 724).

In the smoke detector (1, 1A to 1D) according to the eighth aspect, in the seventh aspect, the light shielding rib (75, 724) extends in a direction intersecting the optical axis (Ax1) of the light emitting element (4). Shape.

According to this aspect, of the light output from the light emitting element (4), the light incident on the light shielding rib (75, 724) is transmitted through the light shielding rib (75, 724) to the optical axis of the light emitting element (4). Along (Ax1), the light is easily reflected toward the light emitting element (4). Therefore, diffusion of light incident on the light shielding ribs (75, 724) in the sensing space (Sp1) is less likely to occur.

In the eighth aspect, the smoke detectors (1, 1A to 1D) according to the ninth aspect are configured to receive the light emitting element (4) and the light receiving element as viewed from one direction orthogonal to one plane (the inner bottom surface 731 of the bottom plate 73). A light shielding wall (74) is further provided on a straight line connecting the element (5). When viewed from one direction orthogonal to one plane, the amount of protrusion (L1) of the light shielding rib (75, 724) from the optical axis (Ax1) of the light emitting element (4) to the light shielding wall (74) side is the light emitting element (4 ) Of the light shielding rib (75, 724) from the optical axis (Ax1) to the opposite side of the light shielding wall (74).

According to this aspect, the gap between the light shielding rib (75, 724) and the light shielding wall (74) can be secured relatively wide, and the degree of freedom of the arrangement of the light shielding wall (74) is increased.

The second to ninth aspects are not essential components for the smoke detectors (1, 1A to 1D) and can be omitted as appropriate.

DESCRIPTION OF

SYMBOLS

1,1A-1D Smoke detector 3 Wall structure 4 Light emitting element 5 Light receiving element 7 Sensing case 8 Light emitting element holder 70 Light shielding structure 75,724 Light shielding rib 700 Inner surface 731,725 Inner bottom surface (one plane)
802 Light-shielding piece 804 Outlet Ax1 Optical axis of light emitting element L1, L2 Projection amount Op1, Op2, Op3 Light path Sp1 Sensing space θ1 Half-value angle

Claims

A sensing case surrounding the sensing space;
A light emitting element that outputs light toward the sensing space;
A light receiving element disposed at a position where direct light from the light emitting element is not incident and scattered light from smoke in the sensing space is incident;
A light shielding structure protruding from the inner surface of the sensing case into the sensing space,
The sensing case includes a wall structure that allows the smoke to pass and suppresses light transmission;
The light shielding structure is located on a path of light output from the light emitting element and reflected one or more times on the inner surface of the sensing case and incident on the light receiving element.
The sensing case has a light emitting element holder for holding the light emitting element,
The smoke detector according to claim 1, wherein the light shielding structure includes a light shielding piece protruding from the light emitting element holder.
The smoke detector according to claim 2, wherein the light-shielding piece is positioned around an exit of the light-emitting element holder where light from the light-emitting element is emitted.
The smoke detector according to any one of claims 1 to 3, wherein a half-value angle of the light emitting element is 25 degrees or more.
The wall structure surrounds the sensing space when viewed from one direction orthogonal to a plane,
The sensing case has a pair of inner bottom surfaces facing each other in the one direction,
The smoke detector according to any one of claims 1 to 4, wherein the light shielding structure includes a light shielding rib protruding from at least one of the pair of inner bottom surfaces.
The smoke detector according to claim 5, wherein the light shielding rib is positioned on a path of light output from the light emitting element and incident on at least one of the pair of inner bottom surfaces.
The smoke detector according to claim 5, wherein the light shielding rib is disposed at a position overlapping the optical axis of the light emitting element when viewed from the one direction orthogonal to the one plane.
The smoke detector according to claim 7, wherein the light shielding rib has a shape extending in a direction intersecting an optical axis of the light emitting element.
A light shielding wall disposed on a straight line connecting the light emitting element and the light receiving element as seen from the one direction orthogonal to the one plane;
The amount of protrusion of the light-shielding rib from the optical axis of the light-emitting element to the light-shielding wall side when viewed from the one direction orthogonal to the one plane is opposite to the light-shielding wall from the optical axis of the light-emitting element. The smoke detector according to claim 8, wherein the smoke detector is smaller than a protruding amount of the light shielding rib.