TW201941171A - Smoke detector - Google Patents

Abstract

Provided is a smoke detector capable of suppressing an increase in stray light while improving detection accuracy. A detector case (7) encloses a detection space (Sp1). A 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. A light-emitting element holder (8) holds the light-emitting element (4). The light-emitting element holder (8) has a light emission guide (84) through which light from the light-emitting element (4) passes. The light emission guide (84) includes an incidence port (805) which opens toward the light-emitting element (4), an emission port (804) which opens toward the detection space (Sp1), and a light-emission-side circumferential surface (806). The light-emission-side circumferential surface (806) encircles the optical axis (Ax1) of the light-emitting element (4) between the incidence port (805) and the emission port (804). The light-emission-side circumferential surface (806) is angled toward the emission port (804) relative to the optical axis (Ax1) of the light-emitting element (4).

Description

Smoke sensor

The present invention relates generally to a smoke sensor, and more specifically, to a smoke sensor that senses smoke by receiving light output from a light emitting element with a light receiving element, and the light output from the light emitting element flows into the sensor Smoke from space scatters.

Document 1 (JP2010-40009A) describes that a light-emitting element (illumination element) irradiates light into a smoke entering a sensing space (smoke-sensing area), and then uses a light-receiving element to receive scattered light generated by the smoke, thereby sensing the smoke Smoke sensor.

The smoke sensor described in Document 1 is in a sensing space surrounded by a plurality of labyrinth walls, and allows smoke to flow into the sensing area through a smoke inflow path formed by a gap between the labyrinth walls. In addition, the labyrinth wall has an external light blocking function that does not make the smoke sensing function unstable due to external light and does not allow external light to enter through the smoke inflow path. In Document 1, the smoke sensor that houses the light-emitting element and the light-receiving element has a substantially circular shape. In addition, in Document 1, the rear portion of the light-emitting element and the light-receiving element (that is, the end portion on the side opposite to the sensing space) is protruded to form a wide sensing space.

In the structure described in Document 1, for example, because dirt and foreign matter intrude into a sensing case (smoke sensing body) surrounding the sensing space, etc., one of the light output by the light emitting element is inside the sensing case. Some parts may be reflected toward the light receiving element. As a result, sometimes not only the scattered light generated by the smoke in the sensing space, but also the reflected light on the inner surface of the sensing case enters the light receiving element, so stray light may increase.

The present disclosure has been made in view of the above-mentioned reasons, and an object thereof is to provide a smoke sensor capable of suppressing an increase in stray light despite an improvement in sensing accuracy.

A smoke sensor according to one aspect of the present disclosure includes a sensing case, a light emitting element, a light receiving element, and a light emitting element holder. The aforementioned sensing case surrounds the sensing space. The light emitting element outputs light to the sensing space. The light receiving element is disposed at a position where the direct light from the light emitting element does not enter and the scattered light generated by the smoke in the sensing space enters. The light emitting element holder holds the light emitting element. The sensing case includes a wall structure that passes the smoke and suppresses light transmission. The light-emitting element holder includes a light-emitting guide through which light from the light-emitting element passes. The light emitting guide includes: an entrance opening opened to the light emitting element, an exit opening opening into the sensing space, and a light emitting side peripheral surface. The light emitting side peripheral surface surrounds the optical axis of the light emitting element between the radiation entrance and the radiation exit. The light-emitting side peripheral surface is inclined with respect to the light axis of the light-emitting element toward the radiation exit side.

(Embodiment 1)
(1) Overview The smoke sensor of this embodiment is a disaster prevention device that reports when it detects smoke generated by a fire or the like. That is, if smoke is generated when a disaster such as a fire occurs, the smoke sensor detects the smoke, and then, for example, outputs a warning sound or communicates with other equipment through a communication function to report the smoke. The “disaster prevention device” in the present disclosure refers to a device installed in a facility for the purpose of preventing a disaster such as a fire, preventing the expansion of a disaster due to a disaster, or recovering from a disaster.

As shown in FIGS. 2A and 2B, the smoke sensor 1 includes a frame 2 and houses various components in the frame 2. The smoke sensor 1 is installed in a facility and used. In the present embodiment, the smoke sensor 1 is exemplified for use in a non-residential facility such as a hotel, an office building, a school, a welfare facility, a commercial facility, a theme park, a hospital, or a factory, but it is not limited to this example. The smoke sensor 1 can also be used in facilities such as a collective house or a single house. The smoke sensor 1 is installed in a facility, for example, in a living room, a hallway, or a stairway of the facility, while being mounted on a ceiling, a wall, or the like.

As shown in FIGS. 1A and 1B, the smoke sensor 1 according to this embodiment includes a sensing case 7, a light emitting element 4, a light receiving element 5 (see FIG. 6), and a light emitting element holder 8. The sensing case 7 surrounds the sensing space Sp1. The light emitting element 4 outputs light to the sensing space Sp1. The light receiving element 5 is disposed at a position where the direct light from the light emitting element 4 does not enter and the scattered light due to the smoke in the sensing space Sp1 enters. Therefore, the smoke sensor 1 can detect the smoke in the sensing space Sp1 according to the light receiving state of the light receiving element 5. The light-emitting element holder 8 holds the light-emitting element 4. The sensing case 7 includes a wall structure 3 (see FIG. 8A) that allows smoke to pass and suppresses light transmission. That is, the wall structure 3 has a function of suppressing light from entering the sensing space Sp1 from outside the sensing space Sp1 and allowing smoke to enter the sensing space Sp1 from outside the sensing space Sp1.

At this time, the light emitting element holder 8 includes a light emitting guide 84 through which light from the light emitting element 4 passes. The light-emitting guide 84 includes a radiation inlet 805 opening to the light-emitting element 4, a radiation outlet 804 opening to the sensing space Sp1, and a light-emitting side peripheral surface 806. The light emitting side peripheral surface 806 surrounds the optical axis Ax1 of the light emitting element 4 between the radiation entrance 805 and the radiation exit 804. The light emitting side peripheral surface 806 is inclined toward the emission port 804 side with respect to the optical axis Ax1 of the light emitting element 4.

According to this structure, when at least a part of the light output from the light emitting element 4 passes through the light emitting guide 84, it enters the light emitting side peripheral surface 806 of the light emitting guide 84. In this case, the light incident on the light-emitting side peripheral surface 806 is reflected on the light-emitting side peripheral surface 806, thereby changing the direction of the light and making the inclination of the light to the optical axis Ax1 of the light-emitting element 4 smaller. That is, since the light emitting side peripheral surface 806 is inclined toward the emission port 804 side with respect to the optical axis Ax1 of the light emitting element 4, the light incident on the light emitting side peripheral surface 806 by the light emitting element 4 is reflected toward the emission port 804. Moreover, since the light-emitting side peripheral surface 806 is provided in the light-emitting element holder 8 in this manner, the positional relationship between the light-emitting side peripheral surface 806 and the light-emitting element 4 can be set with relatively high accuracy, so it is easy to control the light reflected on the light-emitting side peripheral surface 806. Direction. Therefore, for the light output from the emission port 804 after being reflected on the light emitting side peripheral surface 806, the inclination of the light to the optical axis Ax1 of the light emitting element 4 can be suppressed to be relatively small. Thereby, the light output from the emission port 804 after being reflected on the light-emitting side peripheral surface 806 can reduce the possibility of incident on the light-receiving element 5 after being reflected on, for example, the inner surface 700 of the sensing case 7. As a result, it is difficult for the reflected light on the inner surface 700 of the sensing case 7 to enter the light receiving element 5, so the sensing accuracy of the smoke sensor 1 can be improved.

(2) Structure The structure of the smoke sensor 1 according to this embodiment will be described in detail below.

In this embodiment, the smoke sensor 1 is attached to the ceiling of a facility as an example, and is demonstrated. In the following description, in a state where the smoke sensor 1 is mounted on the ceiling, a direction perpendicular (orthogonal) to the horizontal plane is referred to as an "up and down direction" and a downward direction in the up and down direction is referred to as "downward". The arrow showing the "up and down direction" in the figure is just for illustration and has nothing to do with the entity. However, these directions are not intended to limit the use direction (mounting direction) of the smoke sensor 1. For example, the "below" specified here may be front (horizontal) in the actual setting state of the smoke sensor 1.

In addition, the structure of the smoke sensor 1 is schematically shown in each of the drawings described below, and various dimensional relationships in the drawings may be different from the actual ones.

(2.1) Overall Structure First, the overall structure of the smoke sensor 1 according to this embodiment will be described with reference to FIGS. 2A to 5.

The smoke sensor 1 includes a housing 2, a sensing block 10 (see FIG. 3), and a circuit block 20 (see FIG. 3). In this embodiment, the smoke sensor 1 further includes a sound output unit 61 (see FIG. 3) and a battery 62. The constituent elements of the smoke sensor 1 do not necessarily include the battery 62, and the constituent elements of the smoke sensor 1 may not include the battery 62.

The frame body 2 has a circular disk shape in a plan view. The frame 2 is a molded product made of synthetic resin. The housing 2 includes 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 a mounting base fixed to the construction surface.

Here, both the first cover 21 and the second cover 22 are formed in a disc shape and have the same outer peripheral shape in a plan view. Therefore, a combination of the first cover 21 and the second cover 22 constitutes a disc-shaped frame 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 portion 61 are housed between the first cover 21 and the second cover 22.

The first cover 21 includes a circular first main plate 211 and a first peripheral wall 212 protruding upward from an outer peripheral portion of the upper surface of the first main plate 211. In addition, the first cover 21 further includes a circuit area 213 (refer to FIG. 4) for configuring the circuit block 20 on the first main board 211 and a first acoustic area 214 (refer to FIG. 4) for configuring the sound output section 61. Figure 4). The first cover 21 further includes a button 215 disposed in the circuit area 213. The button 215 is configured to be movable with respect to the first main board 211 by a hinge structure, and can be inserted into the inside of the housing 2, that is, an operation above. By pressing the operation button 215, switches included in the circuit block 20 arranged in the circuit area 213 can be operated.

In addition, a groove 216 extending along the outer periphery is formed under the first main board 211 (see FIG. 2A). The groove 216 is substantially concentric with the outer periphery of the lower surface of the first main board 211 and is formed over the entire circumference. That is, the groove 216 has a circular shape that is smaller than the outer periphery of the lower surface of the first main plate 211 by one turn. In addition, a portion of the bottom surface of the groove 216 corresponding to the first acoustic region 214 forms a sound hole 217 (see FIG. 2A) that penetrates the first main plate 211 in the thickness direction of the first main plate 211.

The second cover 22 includes a circular second main plate 221 and a second peripheral wall 222 protruding upward from an outer peripheral portion of the upper surface of the second main plate 221. In addition, the second cover 22 further includes a receiving area 223 (refer to FIG. 3) for configuring the sensing block 10 under the second main board 221 and a second acoustic area 224 for configuring the sound output section 61. The second cover 22 further has a battery area 225 (see FIG. 4) for receiving the battery 62 on the second main board 221.

In addition, the second cover 22 further includes a plurality of partition members 226 protruding downward from the lower surface of the second main board 221. Many of the spacers 226 can ensure a predetermined gap between the first cover 21 and the second cover 22 by contacting each front end portion (lower end portion) with the upper surface of the first main board 211. Specifically, in a state where the first cover 21 and the second cover 22 are combined with each other, an inner space connecting the frame body 2 and an outside of the frame body 2 are formed between an upper end surface of the first peripheral wall 212 and a lower surface of the second main plate 221.的 孔 部 23。 The opening portion 23. Thereby, the smoke can flow into the internal space of the frame body 2 through the opening portion 23, that is, the space between the first cover 21 and the second cover 22.

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 circular disk shape in a 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 has a function as a wall structure 3 (see FIG. 5). The wall structure 3 has a function of suppressing light from entering the sensing space Sp1 from outside the sensing space Sp1 and allowing smoke to enter the sensing space Sp1 from outside the sensing space Sp1. In the internal space of the housing 2, the sensing block 10 is disposed above the circuit block 20. The sensing block 10 senses smoke in a sensing space Sp1 (see FIG. 5) in the sensing case 7.

That is, as shown in FIG. 5, the sensing block 10 is housed in the internal space of the housing 2 together with the circuit block 20 and the like, that is, the space between the first cover 21 and the second cover 22. In addition, the internal space of the frame body 2 is connected to the outside of the frame body 2 through the opening 23 as described above, so that smoke can flow into the internal space of the frame body 2 through the opening portion 23. A portion of the smoke entry path is shown schematically in FIG. 5 by dashed arrows. In addition, the sensing block 10 has a wall structure 3 that allows smoke to enter the sensing space Sp1 from the outside of the sensing space Sp1, so that the smoke flowing into the inner space of the housing 2 can further flow into the sensing space Sp1. Thereby, the smoke in the sensing block 10 can be sensed. The sensing block 10 is described in detail in the column of "(2.2) Structure of the sensing block".

The circuit block 20 includes a printed wiring board 201 and a plurality of electronic components 202 including switches. Many electronic components 202 are mounted on a printed wiring board 201. The light emitting element 4 and the light receiving element 5 of the sensing block 10 are electrically connected to a conductor portion of the printed wiring board 201. In addition, the sound output portion 61 and the battery 62 are also electrically connected to the conductor portion of the printed wiring board 201. In this 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) in the thickness direction of the printed wiring board 201.

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 section 61, and the like, and drives at least the light-emitting element 4 and performs signal processing on the output signal of the light-receiving element 5. During signal processing, the circuit block 20 determines whether there is smoke in the sensing space Sp1 by comparing the light receiving amount (the size of the output signal) with the critical value of the light receiving element 5. The light-receiving amount in the light-receiving element 5 varies depending on, for example, the smoke density and the type of smoke (white smoke, black smoke, etc.) in the sensing space Sp1. Therefore, by comparing the circuit block 20 with the threshold value, when there is smoke in a certain concentration or more in the sensing space Sp1, it is judged as "smoke." When the circuit block 20 detects the presence of smoke, it outputs an electric signal for driving the sound output section 61 to the sound output section 61.

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

The battery 62 is housed in a battery area 225 above the second cover 22. The battery 62 may be a primary battery or a secondary battery.

For example, the constituent elements of the automatic fire notification system include the smoke sensor 1 of this embodiment configured as described above. In addition to the smoke sensor 1, the automatic fire notification system includes, for example, a receiver that receives a notification signal (fire signal) from the smoke sensor 1, and a transmitter that operates a button when a person detects a fire. In the automatic fire notification system, for example, when the occurrence of a fire (the smoke thus generated) is detected by the smoke sensor 1, the smoke sensor 1 sends a notification signal (fire signal) notifying the occurrence of the fire to the receiver.

(2.2) Structure of Sensing Block Next, a more detailed structure of the sensing block 10 will be described with reference to FIGS. 6 to 10. However, each figure described below is a schematic diagram, and the ratio of the length or size of each part in the figure does not necessarily reflect the actual size 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 has a function as a wall structure 3. The sensing space Sp1 is formed inside the sensing case 7. In addition, the sensing case 7 has a light emitting element holder 8 that holds the light emitting element 4. In addition, the sensing case 7 has a light receiving element holder 9 that holds the light receiving element 5. That is, the smoke sensor 1 of this embodiment includes a light-emitting element holder 8 and a light-receiving element holder 9.

In this embodiment, as shown in FIG. 6, the sensing case 7 includes a first case 71 and a second case 72. The second casing 72 is combined with the first casing 71 so as to cover the upper surface of the first casing 71. The first case 71 is fixed to a printed wiring board 201 (see FIG. 3). The first case 71 includes a pair of claws 711 (see FIG. 7) for fixing the first case 71 to the printed wiring board 201. A 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 hooking the peripheral edge of the hole of the printed wiring board 201. In other words, the first case 71 and the printed wiring board 201 are mechanically combined by a snap-fitting method.

Here, both the first casing 71 and the second casing 72 are formed in a circular shape in a plan view, and the outer peripheral shapes are substantially the same in the plan view. Therefore, by combining the first case 71 and the second case 72, a disc-shaped sensing case 7 is formed. The first casing 71 has a pair of claws 712 (refer to FIG. 7) for combining one of the first casing 71 and the second casing 72. A pair of claws 712 protrude upward from the outer peripheral portion of the upper surface of the first casing 71, and hook the outer peripheral surface of the second casing 72 to combine the first casing 71 and the second casing 72. In other words, the first casing 71 and the second casing 72 are mechanically combined by a snap-fitting method. In a state where the first casing 71 and the second casing 72 are coupled to each other, a sensing space Sp1 is formed between the first casing 71 and the second casing 72.

The first case 71 includes a bottom plate 73 and a wall structure 3 that protrudes upward from the outer peripheral portion of the (first) inner bottom surface 731 on 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. In addition, the first housing 71 further includes: a first bracket 81 constituting a part of the light-emitting element bracket 8; and a light-receiving element bracket 9. In addition, the first case 71 further includes a light shielding wall 74 (see FIG. 7) described later, a light shielding rib 75 (see FIG. 7), and an auxiliary light shielding wall 76 (see FIG. 7). The first bracket 81, the light receiving element bracket 9, the light shielding wall 74, the light shielding rib 75, and the auxiliary light shielding wall 76 each protrude upward from the inner bottom surface 731 of the bottom plate 73. Here, the amount of protrusion 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 approximately the same as the amount of protrusion of the wall structure 3 from the inner bottom surface 731 of the bottom plate 73.

The second casing 72 has a circular upper plate 721 and a peripheral wall 722 protruding downward from the outer peripheral portion of the (second) inner bottom surface 725 below the plate 721. The inner diameter of the peripheral wall 722 is larger than the outer diameter of the wall structure 3. In addition, the amount of protrusion of the peripheral wall 722 from the inner bottom surface 725 of the upper plate 721 and the amount of protrusion of the wall structure 3 from the inner bottom surface 731 of the bottom plate 73 are substantially the same. Therefore, in a state where the first casing 71 and the second casing 72 are combined with each other, the front end surface (lower end surface) of the peripheral wall 722 contacts the inner bottom surface 731 of the bottom plate 73 and the front end surface (upper end surface) of the wall structure 3 contacts the upper plate 721 Within the bottom surface 725. In this state, the wall structure 3 is housed in a space surrounded by the peripheral wall 722.

A plurality of window holes 723 penetrating the peripheral wall 722 in the thickness direction of the peripheral wall 722 are formed in 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. Thereby, in a state where the first casing 71 and the second casing 72 are coupled to each other, the wall structure 3 exposes the outside of the sensing casing 7 through the plurality of window holes 723. Here, the insect screen can be installed on the peripheral wall 722 in such a manner as to cover most of the window holes 723. The insect-proof net reduces foreign matter such as insects through most of the window holes 723 into the sensing space Sp1 in the sensing case 7.

In addition, the second casing 72 further includes a second bracket 82 (see FIG. 9), which forms a part of the light-emitting element bracket 8. The second bracket 82 together with the first bracket 81 constitutes the light-emitting element bracket 8. 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. In addition, the second housing 72 has a light shielding rib 724 as a "second light shielding rib" at a position facing the light shielding rib 75 as a "first light shielding rib" in the inner bottom surface 725 of the upper plate 721 (refer to FIG. 9). ).

The light shielding structure 70 protruding from the inner surface 700 (refer to FIG. 11) of the sensing case 7 into the sensing space Sp1 includes a (first) light shielding rib 75 and a (second) light shielding rib 724. That is, the light shielding rib 75 and the light shielding rib 724 constitute at least a part of the light shielding structure 70. The light-shielding structure 70 is described in detail in the column of "(2.3) Structure of the light-shielding structure".
As shown in FIG. 8A, viewed from a direction (upper) perpendicular to the inner bottom surface 731 (a plane) of the bottom plate 73, the wall structure 3 surrounds the sensing space Sp1. FIG. 8A shows a state where the second casing 72 is removed, that is, a plan view of the sensing block 10 of the second casing 72 is omitted. In this embodiment, a circular sensing space Sp1 in a plan view is formed on the inner bottom surface 731 of the bottom plate 73. The wall structure 3 is formed in a circular shape so as to surround the sensing space Sp1 in a plan view. In other words, the annular wall structure 3 is formed on the outer peripheral portion of the inner bottom surface 731 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, a 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 space surrounding the sensing space Sp1 and the sensing space Sp1 is partitioned by the wall structure 3.

At this time, the wall structure 3 has, on both sides in the thickness direction of the wall structure 3, an inner side surface 31 facing the sensing space Sp1 side and an outer side surface 32 facing the side opposite to the sensing space Sp1. The wall structure 3 passes smoke in the thickness direction and suppresses light transmission. That is, the wall structure 3 is a structure having a predetermined thickness in a plan view and has an inner side surface 31 and an outer side surface 32 on both sides in the thickness direction. In this embodiment, the wall structure 3 is the direction of the radius 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, that is, from the periphery of the sensing space Sp1 to the sensing space Sp1. The direction of the center is the thickness direction of the wall structure 3. In addition, the wall structure 3 has a function of allowing smoke to pass between the inner surface 31 and the outer surface 32 and suppressing the transmission of light. Thereby, the wall structure 3 can inhibit light from entering the sensing space Sp1 from outside the sensing space Sp1 and allow smoke to enter the sensing space Sp1 from outside the sensing space Sp1. In this embodiment, the thickness of the wall structure 3 is substantially uniform over the entire circumference, and the outer periphery of the inner bottom surface 731, the inner side surface 31, and the outer side surface 32 are substantially concentric circles in a plan view.

In order to realize the above function, the wall structure 3 has a wall structure 3 penetrating in the thickness direction, that is, a plurality of smoke passage holes 33 penetrating between the inner side surface 31 and the outer side surface 32. Most of the smoke passing holes 33 are arranged in the circumferential direction of the wall structure 3. Thereby, the wall structure 3 can pass smoke through each smoke passage hole 33, and can allow smoke to enter the sensing space Sp1 from outside the sensing space Sp1. Here, each of the smoke passage holes 33 does not pass through the shape between the inner surface 31 and the outer surface 32 in a plan view, but has a shape in which at least a part of the space between the inner surface 31 and the outer surface 32 is curved. That is, at least a part of each of the smoke passage holes 33 has a curved or buckled shape. Therefore, even if the smoke passage holes 33 are passed through the outside 32 side of the wall structure 3, the sensing space Sp1 surrounded by the wall structure 3 cannot be seen. . Thereby, it is possible to suppress the light from passing through the wall structure 3 through the smoke passage holes 33 and to prevent the light from entering the sensing space Sp1 from outside the sensing space Sp1. However, the smoke passage hole 33 does not need to be surrounded by the wall structure 3 over the entire circumference. For example, the wall structure 3 may not have both sides in the vertical direction of the smoke passage hole 33. In addition, the openings on the inner side 31 side and the outer side 32 side of each smoke passage hole 33 may not be arranged on the radius of the sensing space Sp1 in a plan view, that is, radially from the center point P1 of the sensing space Sp1. On a straight line.

Specifically, the wall structure 3 is an assembly of a plurality of small pieces 30 arranged along the inner side surface 31. Smoke can pass between the plurality of small pieces 30 through the wall structure 3. In other words, the small pieces 30 are arranged at intervals on the outer peripheral portion of the inner bottom surface 731 along the outer peripheral edge of the inner bottom surface 731. Most of the small pieces 30 protrude from the inner bottom surface 731 of the bottom plate 73 and constitute a wall structure 3. The amount of protrusion from the bottom surface 731 inside the bottom plate 73 is substantially uniform. The wall structure 3 has smoke passage 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 have both sides of the smoke passage holes 33 in the up-down direction.

The inner side surface 31 is a surface passing through the end edge 301 on the sensing space Sp1 side of the plurality of small pieces 30. The outer side surface 32 is a surface passing through an end edge 302 on the side opposite to the sensing space Sp1 of the plurality of small pieces 30. In short, a smooth curved surface, a flat surface, or a combination of a flat surface and a curved surface connecting the end edges 301 on the sensing space Sp1 side of most of the small pieces 30 corresponds to the inner side surface 31. Similarly, a smooth curved surface, a flat surface, or a combination of a flat surface and a curved surface connecting the end edges 302 opposite to the sensing space Sp1 of the plurality of small pieces 30 corresponds to the outer surface 32.

In other words, the end edge 301 on the sensing space Sp1 side of the plurality of small pieces 30 is located on the inner side surface 31, and the end edge 302 on the opposite side from the sensing space Sp1 of the plurality of small pieces 30 is located on the outer side surface 32. Among the small pieces 30 that are connected to the auxiliary light-shielding wall 76 described later, the small pieces 30 are similar to other small pieces 30 in that the edge 301 on the sensing space Sp1 side is located on the inner side surface 31 and is opposite to the sensing space Sp1 of most small pieces 30. The side end edge 302 is located on the outer side surface 32. As described above, each of the inner side surface 31 and the outer side surface 32 does not have a solid surface in this embodiment, but is an imaginary surface having a predetermined shape by a plurality of small pieces 30. Therefore, in FIG. 8A and FIG. 8B, the inner side surface 31 and the outer side surface 32 are shown by a virtual line (two dotted lines). In FIG. 8A, halftone dots (dotted shadows) are added to a region corresponding to the wall structure 3.

However, the positions of the end edges 301 of most of the small pieces 30 need not be completely consistent with the inner side surface 31, and the positions of the end edges 301 of most of the small pieces 30 may be substantially the same as the inner side surface 31. In the example of FIG. 8A, the position of the end edge 301 of the sensing space Sp1 side of most of the small pieces 30 in most of the small pieces 30 is exactly the same as the inside surface 31, while the positions of the end edges 301 of the remaining small pieces 30 are inside surface 31 Near, but not completely coincident with the inside surface 31. In this way, the inner side surface 31 is defined by the position of the end edge 301 of more than half of the small pieces 30, and the end edge 301 of the remaining small pieces 30 may be near the inner surface 31. The same applies to the outer side surface 32, that is, the positions of the end edges 302 of most of the small pieces 30 need not be completely consistent with the outer side surface 32, and the positions of the end edges 302 of most of the small pieces 30 may be substantially the same as the outer surface 32. That is, the outer side surface 32 is defined by the position of the end edge 302 of more than half of the small pieces 30, and the end edge 302 of the remaining small pieces 30 may be near the outer side surface 32. The term “nearby” here refers to the range of about 20% of the thickness of the wall structure 3 when viewed from the inner side surface 31 or the outer side surface 32.

In this embodiment, the outer side 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 side surface 32 is uniform over the entire circumference. In addition, 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 is closer to the outer side surface 32 than the center point P1. In other words, when a substantially concentric circle with the outer surface 32 is drawn in a plan view, that is, an imaginary circle having a radius (half (1/2)) of the outer surface 32, the inner surface 31 is located between the imaginary circle and the outer surface 32. However, the shape and arrangement of each side surface of the inner side surface 31 and the outer side surface 32 in this way are merely examples, and each side surface of 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 curved portion in a plan view between an edge 301 on the side of the sensing space Sp1 and an edge 302 on the side opposite to the sensing space Sp1. In this embodiment, each of the plurality of small pieces 30 is formed into a substantially L-shape, a substantially V-shape, or a substantially Y-shape in a plan view. With such a shape, each of the smoke passage holes 33 formed by the gap generated between the adjacent pair of small pieces 30 is formed in a curved shape in at least a part between the inner side surface 31 and the outer side surface 32 as described above. . Thereby, the wall structure 3 can realize a function of passing smoke in the thickness direction and suppressing light transmission.

The light emitting element 4 has a light emitting surface 41 (see FIG. 7), and when the power is applied, light is output from the light emitting surface 41. In this embodiment, for example, the light emitting element 4 is a light emitting diode (LED: Light Emitting Diode). As shown in FIG. 6, the light emitting element 4 includes a main body portion 401. A pair of lead terminals 402 protrude from the surface of the body portion 401. Here, a pair of lead terminals 402 are electrically connected to the body portion 401 of the light emitting element 4. The pair of lead terminals 402 are electrically connected to the printed wiring board 201, and the light-emitting element 4 receives power from the circuit block 20 and emits light. Although the components of the light-emitting element 4 do not include a pair of lead terminals 402 in this embodiment, the components of the light-emitting element 4 may include a pair of lead terminals 402.

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 arranged so as to be housed between the inner side surface 31 and the outer side surface 32 of both end surfaces in the thickness direction forming the wall structure 3. In addition, the light emitting element 4 faces the inner surface 31 side, that is, the light emitting surface 41 is disposed on the sensing space Sp1 side. Therefore, the light-emitting element 4 can output light from the light exit surface 41 to the sensing space Sp1 without using an optical element such as a mirror.

In this 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 exit surface 41 and the back surface 42. FIG. 9 is an enlarged sectional view of a region Z1 in FIG. 5. A pair of leads electrically connected to the light emitting element 4 protrudes from the bottom surface 43. In this embodiment, the lead wires protruding from the bottom surface 43 are lead terminals. In other words, the light emitting element 4 has a light emitting surface 41 and a back surface 42 on both sides in the thickness direction of the wall structure 3 of the main body portion 401. In addition, the lead terminal 402 does not protrude from the light emitting surface 41 and the back surface 42, but protrudes from the bottom surface 43 adjacent to both 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 projecting surface (bottom surface 43) of the lead terminal 402 faces downward.

In addition, in this embodiment, the leads (lead terminals 402) protrude from the light emitting element 4 in a direction orthogonal to the optical axis Ax1 (see FIG. 10) of the light emitting element 4 (here, below). That is, as described above, the lead terminal 402 protrudes downward from the bottom surface 43, and a curved structure is not adopted in a part of the lead terminal 402. The lead terminal 402 can be extended downward by the light emitting element 4.

Compared with a light-emitting element having a structure in which a lead terminal protrudes from a surface opposite to the light exit surface, the light-emitting element 4 thus configured can reduce the thickness direction of the wall structure 3, for example, as a so-called cannonball type light-emitting diode. On the space. That is, in the side-view type light emitting diode, the lead terminal 402 protruding from the bottom surface 43 can be projected in a direction orthogonal to the thickness direction of the wall structure 3 by the light emitting element 4 with the light emitting surface 41 toward the inner side 31 side. . Thereby, the thickness direction dimension of the wall structure 3 can be suppressed to be relatively small, and as described above, the light exit surface 41 can be disposed toward the inner side surface 31 side between the inner side surface 31 and the outer side surface 32 of the wall structure 3. Light emitting element 4.

Here, the bottom surface 43 extends along the inner bottom surface 731 (one plane) of the bottom plate 73. In this 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 may extend 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 portion 412 protrudes into a dome shape from the flat portion 411 and has a function of a convex lens. As shown in FIG. 9, the main body portion 401 includes a light emitting portion 403 and a lead portion 404. The light emitting portion 403 is mounted on a surface of the lead portion 404 facing the outer side surface 32 side, and emits light when the current is applied. The lead portion 404 is configured integrally with the lead terminal 402.

The light receiving element 5 is an element that performs photoelectric conversion that converts light into an electrical signal. In this embodiment, for example, the light receiving element 5 is a photodiode (PD: Photodiode). As shown 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 portion 501 is housed in the metal cover 503 such that at least the light receiving surface of the main body portion 501 is exposed through the hole of the metal cover 503. A pair of lead terminals 502 protrude from the lower surface of the main body portion 501. Here, a pair of lead terminals 502 are electrically connected to the body portion 501 of the light receiving element 5. The pair of lead terminals 502 are electrically connected to the printed wiring board 201, and the light receiving element 5 is electrically connected to the circuit block 20.

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

Next, as shown in FIG. 8A, in a plan view, the light emitting element 4 and the light receiving element 5 are arranged in a positional relationship in which the optical axis Ax1 of the light emitting element 4 and the optical axis Ax2 of the light receiving element 5 cross each other. 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 a plan view. If the light-emitting element 4 and the light-receiving element 5 have the positional relationship as described above, the direct light from the light-emitting element 4 does not enter the light-receiving element 5. On the other hand, when the smoke flows into the sensing space Sp1, the light from the light emitting element 4 is scattered by the smoke existing at the center point P1 of the sensing space Sp1, and at least a part of the scattered light is received by the light receiving element 5.

Thus, in a state where the smoke does not exist in the sensing space Sp1, the light receiving element 5 does not receive the light output from the light emitting element 4, and in a state where the smoke is in the sensing space Sp1, the light receiving element 5 receives the output from the light emitting element 4 and because Light scattered by smoke (scattered light). Therefore, the smoke sensor 1 can detect the smoke in the sensing space Sp1 according to the light receiving state of the light receiving element 5.

At this time, in this embodiment, the light-emitting element 4 is housed within the thickness of the wall structure 3 as described above, and therefore, compared with the structure in which the light-emitting element 4 protrudes from the inner side surface 31 of the wall structure 3, a wide sensing can be ensured Space Sp1. If the sensing space Sp1 is wide, the freedom of arrangement of the light shielding wall 74 in the sensing space Sp1 is high. In addition, if the sensing space Sp1 is wide, the light shielding wall 74 may be disposed at a position relatively far from the center point P1 of the sensing space Sp1.

In this embodiment, as shown in FIG. 10, the optical axis Ax1 of the light emitting element 4 and the optical axis Ax2 of the light receiving element 5 extend along the inner bottom surface 731 (one plane) of the bottom plate 73. FIG. 10 is an end view along line A1-A1 in FIG. 7. 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 base plate 73. In addition, 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 located at substantially the same height as the inner bottom surface 731 of the bottom plate 73.

In addition, the light shielding rib 75 is disposed on the front surface of the light emitting element 4 in a plan view, that is, a position facing the light emitting surface 41 of the light emitting element 4. As shown in FIG. 9, a certain gap is created between the light shielding rib 75 and the light shielding rib 724 provided in the second case 72. The optical axis Ax1 of the light-emitting element 4 passes through a gap between the light-shielding rib 75 and the light-shielding rib 724. Therefore, the light-shielding rib 75 and the light-shielding rib 724 can suppress 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 can be suppressed from being reflected on the upper surface (inner bottom surface 731) of the bottom plate 73 or on the lower surface (inner bottom surface 725) of the upper plate 721.

In addition, the auxiliary light-shielding wall 76 has a shape of one of the plurality of small pieces 30 that continue to constitute the wall structure 3 and is located between the light-shielding wall 74 and the light-receiving element holder 9. The auxiliary light shielding wall 76 protrudes from the inner side surface 31 of the wall structure 3 into the sensing space Sp1. The auxiliary shading wall 76 has a function of suppressing stray light from being generated inside the sensing space Sp1 due to reflection of light on the inner bottom surface 731 of the bottom plate 73 or the inner bottom surface 725 of the upper plate 721, and also allows smoke to flow into the sensing space Sp1 Improved performance. That is, the auxiliary light shielding wall 76 is a structure other than the small piece 30 for preventing light from entering the wall structure 3 of the sensing space Sp1 from the outside of the sensing space Sp1. In FIG. 7, a boundary line between the auxiliary light shielding wall 76 and the small piece 30 is indicated by an imaginary line (two dotted lines).

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

In the present embodiment, the light-emitting element holder 8 is arranged to be housed in a region surrounded by the outer surface 32. That is, the light-emitting element holder 8 (including the first holder 81) is not exposed from the outer side surface 32 and is formed in a shape to be housed in a region surrounded by the outer side surface 32.

In addition, the light-emitting element holder 8 has a through-hole 801 for electrically connecting to a lead wire of the light-emitting element 4. In this embodiment, the lead wire passing through the through hole 801 is a lead terminal 402. A through-hole 801 is formed in the first bracket 81. At this time, as shown in FIG. 8B, the through-holes 801 are formed between the inner surface 31 and the outer surface 32 and closer to the outer surface 32 than the inner surface 31. In other words, as shown in FIG. 8A, when a center line C1 that divides the wall structure 3 in the thickness direction by two is drawn in a plan view, the through-line hole 801 is located between the center line C1 and the outer side surface 32.

As shown in FIG. 7, the light-emitting element holder 8 further includes a light shielding sheet 802. The light shielding sheet 802 protrudes into the sensing space Sp1 from a surface of the first bracket 81 facing the sensing space Sp1. Here, the light-shielding sheet 802 protrudes from the end portion on the side of the first bracket 81 away from the light-shielding wall 74 in the circumferential direction of the wall structure 3. The light-shielding sheet 802 has a function of shielding light output from the light-emitting element 4 and reflected on the surface of the light-emitting element holder 8.

The light shielding structure 70 protruding from the inner surface 700 (refer to FIG. 11) of the sensing case 7 into the sensing space Sp1 includes a light shielding sheet 802. That is, in this embodiment, the light shielding sheet 802 together with the light shielding rib 75 and the light shielding rib 724 constitute at least a part of the light shielding structure 70. The light-shielding structure 70 is described in detail in the column of "(2.3) Structure of the light-shielding structure".

As shown in FIG. 9, the light-emitting element holder 8 further includes a positioning surface 803. The positioning surface 803 is a surface that intersects the optical axis Ax1 of the light-emitting element 4, and the light-emitting element 4 is positioned 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 this embodiment, the light-emitting element holder 8 is divided into the two members of the first bracket 81 and the second bracket 82 as described above. Therefore, the positioning surface 803 is also formed by the two members of the first bracket 81 and the second bracket 82. .

In addition, in this embodiment, the positioning surface 803 has elasticity, that is, spring property. The positioning surface 803 causes an elastic force pressing the light emitting element 4 from the outer surface 32 side to act on the light emitting element 4. In this embodiment, since the light-emitting element holder 8 is made of synthetic resin, at least the second holder 82 has a function as a resin spring, and the positioning surface 803 can be provided with the above-mentioned elasticity.

The light receiving element holder 9 holds the light receiving element 5. Here, as shown in FIG. 8A, 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. Specifically, the light-receiving element holder 9 is disposed between a 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 recessed portion into which the light receiving element 5 is fitted.

(2.3) Structure of Light-shielding Structure Next, a more detailed structure of the light-shielding structure 70 will be described with reference to FIGS. 11, 12A, and 12B. In FIG. 12A and FIG. 12B, a part of a path (light path) of the light output from the light emitting element 4 is schematically shown by a dotted arrow. However, each figure described below is a schematic diagram, and the ratio of the length or size of each part in the figure does not necessarily reflect the actual size ratio.

The smoke sensor 1 of this 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. In the present disclosure, the “inner surface 700 of the sensing case 7” is a surface that becomes the inner side of the sensing case 7 and is a surface that faces the sensing space Sp1 side, which is an internal space of the sensing case 7. In this embodiment, the inner surface 700 of the sensing case 7 includes: the inner side surface 31 of the wall structure 3, the inner bottom surface 731 of the first case 71 (the upper surface of the bottom plate 73), and the inner bottom surface 725 of the second case 72. (Below the upper plate 721). In addition, the inner surface 700 of the sensing case 7 also includes a surface facing the sensing space Sp1 in the light emitting element holder 8 and the light receiving element holder 9.

The smoke sensor 1 according to this embodiment includes the light shielding sheet 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 sheets 802, the light shielding ribs 75, and the light shielding ribs 724 all protrude from the inner surface 700 of the sensing case 7 into the sensing space Sp1. In addition, the light-shielding sheet 802, the light-shielding rib 75, and the light-shielding rib 724 are located on the paths Op1, Op2, Op3 of the light output from the light-emitting element 4 and reflected more than once on the inner surface 700 of the sensing case 7 and incident on the light-receiving element 5. (Please refer to Figs. 12A and 12B).

By providing such a light-shielding structure 70, the smoke sensor 1 can shield at least one of the light that is output by the light-emitting element 4 and reflected at least once on the inner surface 700 of the sensing case 7 and enters the light-receiving element 5 Part. That is, it is difficult to control the reflection direction of the light reflected on the inner surface 700 of the sensing case 7 to be the same, and it is greatly changed due to the intrusion of dirt and foreign matter into the sensing case 7 surrounding the sensing space Sp1. Therefore, when the reflected light of the inner surface 700 of such a sensing case 7 enters the light receiving element 5, it affects the amount of light received by the light receiving element 5 (the size of the output signal), and further detects the smoke sensor 1. The results have an impact. In short, the light output from the light emitting element 4 and reflected once or more on the inner surface 700 of the sensing case 7 becomes so-called "stray light" and becomes a factor that reduces the sensing accuracy of the smoke sensor 1. The smoke sensor 1 of the present embodiment shields at least a part of the stray light as described above with the light-shielding structure 70. Although the sensing accuracy is improved, the increase in stray light can be suppressed.

More specifically, in this embodiment, as shown in FIG. 11, the sensing case 7 includes a light-emitting element holder 8 that holds the light-emitting element 4. The light shielding structure 70 includes a light shielding sheet 802 protruding from the light emitting element holder 8. The light-shielding sheet 802 protrudes from the surface of the light-emitting element holder 8 toward the sensing space Sp1 into the sensing space Sp1. Here, an emission port 804 in the light-emitting element holder 8 that emits light from the light-emitting element 4 is formed in a surface of the light-emitting element holder 8 that faces the sensing space Sp1 side. In addition, the light shielding sheet 802 is located around the radiation outlet 804 of the light emitting element holder 8. Here, the light shielding sheet 802 is not disposed on the entire periphery of the emission port 804, but is disposed on only one side of the emission port 804 in a plan view. Specifically, when viewed from the emission port 804, the light shielding sheet 802 is disposed at a position on the opposite side of the wall structure 3 from the light shielding wall 74. In short, the light-shielding sheet 802 is formed asymmetrically with respect to the optical axis Ax1 of the light-emitting element 4 in a plan view (see FIG. 12A). Since the light-shielding sheet 802 is asymmetrical, a structure that can become a stray light component is easily shielded by the light-shielding sheet 802, and the light reaching the light receiving element 5 after being scattered by the smoke in the sensing space Sp1 is difficult to be shielded by the light-shielding sheet 802. Therefore, according to the light shielding sheet 802 having such a structure, it is possible to suppress the increase of stray light even though the improvement of the sensing accuracy is achieved.

In addition, the light shielding sheet 802 is formed integrally with the first bracket 81 provided in the first case 71, and in a plan view, it forms a triangle with a tapered front end side. In addition, the light-shielding sheet 802 is formed with a substantially full width in the up-down direction of the sensing space Sp1. That is, in the sensing space Sp1, the light shielding sheet 802 is formed between a pair of inner bottom surfaces 731 and 725 located on both sides of the sensing space Sp1 in the upper and lower directions.

As shown in FIG. 12A, the light-shielding sheet 802 of the structure described above is located on the light-receiving element outputted from the light-emitting element 4 and reflected on the surface of the light-emitting element holder 8 and reflected more than once on the inner surface 700 of the sensing case 7 and enters the light-receiving element. 5 light path Op1. That is, at least a part of the light output from the light emitting element 4 and reflected once or more on the inner surface 700 of the sensing case 7 and incident on the light receiving element 5 is shielded by the light shielding sheet 802 of the light shielding structure 70.

If there is no light shielding sheet 802, the light passing through the passage Op1 is reflected on the inner side surface 31 of the wall structure 3 included in the inner surface 700 of the sensing case 7, and sometimes enters the light receiving element 5. In the smoke sensor 1 of this embodiment, since the light-shielding sheet 802 is located on such a path Op1, the light passing through the path Op1 can be shielded by the light-shielding sheet 802, and thus the generation of "stray light" can be suppressed. However, because the inner surface 31 of the wall structure 3 included in the inner surface 700 of the sensing case 7 is not a solid surface, but an imaginary surface whose shape is defined by most of the small pieces 30, strictly speaking, the light of the inner surface 31 The reflection is generated on the surface of most of the small pieces 30.

Here, in this embodiment, the half-value angle q1 of the light-emitting element 4 is 25 degrees or more. The so-called "half-value angle" in the present disclosure refers to an angle (q1) when the brightness on the optical axis Ax1 is 100%, and the brightness reduction ratio when the light axis Ax1 is gradually moved away from the optical axis is 50%. As described above, when a relatively wide-angle element having a half-value angle q1 of 25 degrees or more is used as the light-emitting element 4, reflection on the surface of the light-emitting element holder 8 is likely to occur, and the light beam passing through the path Op1 is large. Therefore, the configuration in which the light shielding sheet 802 is provided as the light shielding structure 70 in this embodiment is particularly useful.

In addition, in a plan view, a path of light is also generated at a position symmetrical to the optical axis Ax1 of the light-emitting element 4 and the above-mentioned path Op1. However, since the light on such a path is output from the emission port 804 to the light shielding wall 74 (see FIG. 7), it is blocked by the light shielding wall 74 and it is difficult to form stray light. Therefore, in a plan view, even if the light shielding sheet 802 is provided only on one side of the emission port 804, the light shielding sheet 802 can sufficiently suppress the occurrence of "stray light".

In addition, as shown in FIG. 11, the sensing case 7 has a pair of inner bottom surfaces 731 and 725 facing each other in the up-down direction (one direction) as a part of the inner surface 700 of the light shielding structure. In addition, the sensing case 7 includes light shielding ribs 75 and 724 protruding from at least one inner bottom surface of the pair of inner bottom surfaces 731 and 725 as the light shielding structure 70. In this embodiment, the light shielding ribs 75 and 724 protrude from a pair of inner bottom surfaces 731 and 725, respectively. That is, the light-shielding structure 70 includes a (first) light-shielding rib 75 protruding upward from the inner bottom surface 731 of the first casing 71 and a (second) light-shielding rib protruding downward from the inner bottom surface 725 of the second casing 72. 724.

Here, the light-shielding rib 75 and the light-shielding rib 724 are formed so that the front end surfaces face each other. In addition, a certain gap is ensured between the two light shielding ribs 75 and 274. As shown in FIG. 12B, the optical axis Ax1 of the light-emitting element 4 passes through a gap between the light-shielding rib 75 and the light-shielding rib 724. Therefore, by the light-shielding rib 75 and the light-shielding rib 724, it is possible to suppress 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 located on the paths Op2 and Op3 of the light output from the light emitting element 4 and incident on at least one of the inner surfaces of the pair of inner bottom surfaces 731 and 725. In this embodiment, the light-shielding rib 75 arranged below the optical axis Ax1 of the light-emitting element 4 is located on the path Op2 of the 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 located on the path Op3 of the light output from the light-emitting element 4 and incident on the inner bottom surface 725.

The light-shielding ribs 75 and 724 are arranged at positions overlapping the optical axis Ax1 of the light-emitting element 4 in a plan view (see FIG. 12A). Specifically, the light shielding rib 75 and the light shielding rib 724 are both arranged on the front surface of the light emitting element 4 in a plan view. In FIG. 12A, although only the light-shielding rib 75 is shown, the position and shape of the light-shielding rib 724 in the plan view are also the same as those of the light-shielding rib 75.

The light shielding ribs 75 and 724 have a shape extending in a direction crossing the optical axis Ax1 of the light emitting element 4. Specifically, each of the light shielding rib 75 and the light shielding rib 724 is formed in a flat plate shape orthogonal to the optical axis Ax1 of the light emitting element 4. Therefore, light entering the light-shielding rib 75 and the light-shielding rib 724 of the light output from the light-emitting element 4 is easily reflected by the light-shielding rib 75 or the light-shielding rib 724 to the light-emitting element 4 side along the optical axis Ax1 of the light-emitting element 4. Therefore, it is difficult for light entering the light shielding rib 75 and the light shielding rib 724 to be diffused in the sensing space Sp1.

Here, as shown in FIG. 12A, in the plan view, the amount of protrusion 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 smaller than that of the light shielding ribs 75 and 724 by the optical axis Ax1 of the light emitting element 4. The amount of protrusion L2 to the side opposite to the light shielding wall 74 is small (L1 <L2). Specifically, when viewed from the optical axis Ax1 of the light emitting element 4, the light shielding ribs 75 and 724 are arranged at positions on the side opposite to the light shielding wall 74 in the circumferential direction of the wall structure 3. 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 a plan view.

As shown in FIG. 12B, the light-shielding ribs 75 and 724 of the structure described above are located at the light path Op2 of the light output from the light-emitting element 4 and reflected once or more on the inner surface 700 of the sensing case 7 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 once or more on the inner surface 700 of the sensing case 7 into the light-receiving element 5 is shielded by the light-shielding ribs 75 and 724 of the light-shielding structure 70.

Without the light-shielding ribs 75 and 724, the light passing through the passages 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 sometimes enters the light-receiving element 5. In the smoke sensor 1 of this embodiment, since the light-shielding rib 75 is located on such a passage Op2, the light passing through the passage Op2 can be shielded by the light-shielding rib 75, and thus the generation of "stray light" can be suppressed. The passage Op3 is similarly located on the passage Op3 because the light-shielding rib 724 is located on the passage Op3. Therefore, the light passing through the passage Op3 can be shielded by the light-shielding rib 724, and thus the generation of "stray light" can be suppressed.

In addition, although the light is also output to the light shielding wall 74 (refer to FIG. 7) from the emission port 804 in a plan view, such light is blocked by the light shielding wall 74, so it is difficult to form stray light. Therefore, as in the present embodiment, even in a plan view, even if the light shielding ribs 75 and 724 are arranged at a position opposite to the light shielding wall 74 viewed from the optical axis Ax1 of the light emitting element 4, the light shielding rib 75 can also be used. , 724 sufficiently suppresses the generation of "stray light".

(2.4) Structure of Light-Emitting Element Holder and Light-Receiving Element Holder Next, more detailed structures of the light-emitting element holder 8 and the light-receiving element holder 9 will be described with reference to FIGS. 1A, 1B, 13A, and 13B. However, each figure described below is a schematic diagram, and the ratio of the length or size of each part in the figure does not necessarily reflect the actual size ratio.

In the smoke sensor 1 of this embodiment, the sensing case 7 includes the light-emitting element holder 8 and the light-receiving element holder 9 as described above. The light-emitting element holder 8 holds the light-emitting element 4. The light receiving element holder 9 holds the light receiving element 5.

As shown in FIGS. 1A and 1B, the light-emitting element holder 8 includes a light-emitting holding portion 83 and a light-emitting guide 84. The light emitting holding portion 83 holds the light emitting element 4 and has a function of positioning the light emitting element 4. That is, the light emitting holding portion 83 includes the positioning surface 803 described above. On the other hand, the light emitting guide 84 is located on the front side of the light emitting element 4 and is a portion through which light from the light emitting element 4 passes. That is, the light emitting guide 84 has a function of orienting (leading) the light from the light emitting element 4 to the sensing space Sp1 by passing the light from the light emitting element 4. Although the light emitting holding portion 83 and the light emitting guide 84 are integrated, a boundary line between the light emitting holding portion 83 and the light emitting guide 84 is shown by an imaginary line (two dotted lines) in FIGS. 1A and 1B and the like. In this embodiment, 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. Therefore, the light-emitting holding section 83 and the light-emitting guide 84 also pass through the first holder 81 and the first holder 81, respectively. Two members of the two brackets 82 are formed.

As shown in FIGS. 1A and 1B, the light emitting guide 84 includes an entrance 805 opening to the light emitting element 4, an exit 804 opening to the sensing space Sp1, and a light emitting side peripheral surface 806. Specifically, the light emitting guide 84 is formed in a cylindrical shape, and light from the light emitting element 4 passes through the internal space of the light emitting guide 84. At this time, the light from the light-emitting element 4 enters the internal space of the light-emitting guide 84 through the entrance port 805, and exits to the sensing space Sp1 through the exit port 804. Here, the light emitting side peripheral surface 806 is a surface arranged so as to surround the optical axis Ax1 of the light emitting element 4 between the radiation entrance 805 and the radiation exit 804. In this embodiment, since the light emitting guide 84 is cylindrical, the light emitting side peripheral surface 806 is an inner peripheral surface of the light emitting guide 84.

At this time, as shown in FIGS. 1A and 1B, the light-emitting side peripheral surface 806 is inclined toward the emission exit 804 side with respect to the optical axis Ax1 of the light-emitting element 4. That is, the light emitting side peripheral surface 806 is not parallel to the optical axis Ax1 of the light emitting element 4 but is inclined with respect to the optical axis Ax1 of the light emitting element 4. In particular, in this embodiment, the light emitting guide 84 has a cylindrical shape. Therefore, the light emitting side peripheral surface 806 is relatively opposed to the light emitting element in such a manner that the inner diameter of the light emitting guide 84 gradually increases from the radiation entrance 805 toward the radiation exit 804. The optical axis Ax1 of 4 is inclined.

In addition, in this embodiment, the light emitting side peripheral surface 806 has a shape formed along a paraboloid of revolution with the optical axis Ax1 of the light emitting element 4 as a central axis. That is, as shown in FIGS. 1A and 1B, the surface generated when the parabola Pr1 is rotated around the optical axis Ax1 of the light emitting element 4, that is, the rotating body of the parabola Pr1 forms a light emitting side peripheral surface 806. The parabola Pr1 is an imaginary line with an intersection (apex) with the optical axis Ax1 as a reference point P11.

According to the structure described above, when the light output from the light emitting element 4 passes through the light emitting guide 84, it is reflected on the light emitting side peripheral surface 806, so the direction of the light is changed so that the inclination of the light with respect to the optical axis Ax1 of the light emitting element 4 becomes small. Moreover, since the light-emitting side peripheral surface 806 is provided in the light-emitting element holder 8 in this manner, the positional relationship between the light-emitting side peripheral surface 806 and the light-emitting element 4 can be set with relatively high accuracy, so it is easy to control the light reflected on the light-emitting side peripheral surface 806. Direction. In short, the light emitting side peripheral surface 806 has a function of converting light output from the light emitting element 4 into light close to parallel light along the optical axis Ax1 of the light emitting element 4. As a result, it is difficult for the light output from the emission port 804 of the light emitting guide 84 to enter the inner surface 700 and the like of the sensing case 7, so that formation of so-called "stray light" can be reduced and the sensing accuracy of the smoke sensor 1 can be reduced. possibility.

In particular, in this embodiment, since the light emitting side peripheral surface 806 has a shape formed along a rotating parabola, for example, light emitted from the reference point P11 is reflected on the light emitting side peripheral surface 806 in a direction close to the optical axis Ax1. Therefore, for example, since the light emitting section 403 (see FIG. 9) is located on the reference point P11, light is easily output along the optical axis Ax1. In other words, the near-parallel light is output from the emission port 804. In FIG. 1A and FIG. 1B, a part of a path (light path) of light output from the light emitting element 4 is schematically indicated by a dotted arrow.

In addition, if the light emitting section 403 is near the focal point of the parabola Pr1, the light output from the light emitting element 4 is reflected on the light emitting side peripheral surface 806 in a direction closer to the optical axis Ax1. That is, light that is closer to parallel light is output from the emission port 804.

As shown in FIGS. 13A and 13B, the light receiving element holder 9 includes a light receiving holding portion 91 and a light receiving guide 92. The light receiving holding section 91 holds the light receiving element 5 and has a function of positioning the light receiving element 5. On the other hand, the light-receiving guide 92 is located on the front side of the light-receiving element 5 and is a portion through which light entering the light-receiving element 5 passes. That is, the light receiving guide 92 has a function of orienting (leading) light from the sensing space Sp1 to the light receiving element 5 by passing light from the light receiving element 5. Although the light receiving holder 91 and the light receiving guide 92 are integrated, a boundary line between the light receiving holder 91 and the light receiving guide 92 is shown by an imaginary line (two dotted lines) in FIGS. 13A and 13B and the like.

As shown in FIG. 13B, the light receiving guide 92 includes an introduction port 901 opened to the sensing space Sp1, an extraction port 902 opened to the light receiving element 5, and a light receiving side peripheral surface 903. Specifically, the light receiving guide 92 is formed in a cylindrical shape, and the light entering the light receiving element 5 from the sensing space Sp1 passes through the internal space of the light receiving guide 92. At this time, the light from the sensing space Sp1 enters the internal space of the light receiving guide 92 through the introduction port 901, and exits to the light receiving element 5 through the extraction port 902. Here, the light-receiving-side peripheral surface 903 is a surface arranged so as to surround the optical axis Ax2 of the light-receiving element 5 between the introduction port 901 and the extraction port 902. In this embodiment, since the light receiving guide 92 has a cylindrical shape, the light receiving side peripheral surface 903 is an inner peripheral surface of the light receiving guide 92. However, the inner peripheral surface of the light-receiving guide 92 does not have the function as the light-receiving-side peripheral surface 903 in its entirety, but only the two side surfaces facing each other across the optical axis Ax2 in the plan view function as the light-receiving-side peripheral surface 903.

At this time, as shown in FIG. 13B, the light-receiving-side peripheral surface 903 is inclined with respect to the optical axis Ax2 of the light-receiving element 5 toward the guide entrance 901 side. That is, the light-receiving-side peripheral surface 903 is not parallel to the optical axis Ax2 of the light-receiving element 5, but is inclined with respect to the optical axis Ax2 of the light-receiving element 5.

In the present embodiment, the light-receiving-side peripheral surface 903 is planar. Therefore, in a plan view, the light-receiving-side peripheral surface 903 is linear. In addition, in the plan view, the width dimensions of the introduction port 901 and the extraction port 902 are substantially the same. Here, in a plan view, the internal space of the light receiving guide 92 surrounded by the light receiving side peripheral surface 903 is formed to have a width larger than the introduction port 901 and the extraction port 902. In other words, the internal space of the light receiving guide 92 is formed into a shape in which the cross section orthogonal to the optical axis Ax2 is the smallest in the introduction port 901 and the extraction port 902.

According to the structure described above, when the light incident on the light receiving element 5 passes through the light receiving guide 92, it is reflected on the light receiving side peripheral surface 903. Therefore, light having a relatively large inclination with respect to the optical axis Ax2 of the light receiving element 5 is difficult to reach the light receiving element 5. That is, as shown in the path Op5 in FIGS. 13A and 13B, when a part of the light output from the light emitting element 4 enters any one of the small pieces 30, the light is reflected on the small piece 30. At this time, for example, a part of the light that is multiple-reflected in the plurality of small pieces 30 enters the internal space of the light receiving guide 92 through the introduction port 901. In this case, as shown by the path Op5 in FIGS. 13A and 13B, at least a part of the light incident into the internal space of the light receiving guide 92 is reflected on the light receiving side peripheral surface 903 to the side opposite to the light receiving element 5, that is, Introduction port 901. In other words, the light incident on the light-receiving element 5 after being reflected on the light-receiving-side peripheral surface 903 is restricted to light close to the optical axis Ax2.

In brief, in the examples of FIGS. 13A and 13B, the light entering the internal space of the light receiving guide 92 from the introduction port 901 through the passage Op5 is reflected twice on the light receiving side peripheral surface 903 and does not reach the light receiving element 5. It is emitted from the introduction port 901 to the sensing space Sp1. In addition, since the light-receiving-side peripheral surface 903 is provided in the light-receiving element holder 9 in this manner, the positional relationship between the light-receiving-side peripheral surface 903 and the light-receiving element 5 can be set with relatively high accuracy, and therefore it is easy to control the light reflected on the light-receiving-side peripheral surface 903. Direction. As a result, light that is reflected on the inner surface 700 of the sensing case 7 and the like and forms "stray light" that reduces the sensing accuracy of the smoke sensor 1 hardly reaches the reference point P12 located at the light receiving portion of the light receiving element 5.

(3) The smoke sensor 1 according to the first modification is only one of the various embodiments of the present disclosure. If the smoke sensor 1 of the first embodiment can achieve the purpose of cost disclosure, various changes can be made according to the design and the like. Hereinafter, modifications of the first embodiment will be listed. Modifications described below can be used in appropriate combination.

As shown in FIG. 14, the front end faces of the light-shielding ribs 75 and 724 may include inclined portions 75 a and 724 a that are inclined with respect to the optical axis Ax1 (see FIG. 1B) of the light-emitting element 4 to the side opposite to the light-emitting element 4. That is, the light-shielding rib 75 and the light-shielding rib 724 are formed so that the front end surfaces face each other and a gap is secured between them. The inclined portion 75 a of the light-shielding rib 75 is inclined so that the gap between the light-shielding rib 724 and the light-shielding rib 724 gradually increases as the distance from the light-emitting element 4 increases. The inclined portion 724 a of the light shielding rib 724 is inclined so that the gap between the light shielding rib 724 and the light shielding rib 75 gradually increases as the distance from the light emitting element 4 increases. In particular, in the example of FIG. 14, the inclined portions 75 a and 724 a have a shape formed along a paraboloid of revolution around the optical axis Ax1 of the light-emitting element 4 as the light-emitting side peripheral surface 806. Therefore, when the light output from the light-emitting element 4 passes between the pair of light-shielding ribs 75 and 724, it is reflected at the inclined portions 75a and 724a. Therefore, the direction of the light is changed to reduce the inclination of the light to the optical axis Ax1 of the light-emitting element 4.

That is, in the modified example shown in FIG. 14, the inclined portions 75 a and 724 a have light similar to the light-emitting side peripheral surface 806 and convert light output from the light-emitting element 4 into light parallel to parallel light along the optical axis Ax1 of the light-emitting element 4. Function. In addition, since a gap is originally secured between the pair of light shielding ribs 75 and 724, the light is not prevented from spreading in the horizontal direction (the direction orthogonal to both the vertical direction and the optical axis Ax1 of the light emitting element 4). Therefore, in the structure shown in FIG. 14, as compared with the case where the light emitting guide 84 is extended along the optical axis Ax1 of the light emitting element 4, the light amount can be suppressed from being reduced to a small level without merely preventing the light from spreading in the horizontal direction. Here, it is not necessary that both of the pair of light shielding ribs 75 and 724 have inclined portions 75a and 724a, and only one of the light shielding ribs 75 (or 724) may have inclined portions 75a (724a).

In the first embodiment, although the wall structure 3 is formed of an assembly of a plurality of small pieces 30, the wall structure 3 is not limited to this structure, and the wall structure 3 may be a continuous body "wall" in the circumferential direction. In this case, by having the wall structure 3 having a plurality of smoke passage holes 33 penetrating the wall structure 3 in the thickness direction, the function of passing smoke in the thickness direction and suppressing light transmission can be achieved.

In addition, in Embodiment 1, although the structure in which the sensing block 10 is housed in the internal space of the frame 2 is shown, it is not limited to this structure, and for example, at least a part of the sensing block 10 may be projected by the frame 2 structure. In addition, the housing 2 is not a necessary structure in the smoke sensor 1 and can be appropriately omitted.

In addition, in the first embodiment, although the case where the sensing case 7 and the sensing space Sp1 are circular in a plan view is described, it is not limited to this structure. The sensing case 7 or the sensing space Sp1 may also be, for example, in The plan view is oval or polygonal. In this case, the wall structure 3 is also oval or polygonal in a plan view.

In addition, in the first embodiment, although a part of the light-emitting element holder 8 is arranged to be exposed into the sensing space Sp1 from the inner side surface 31 of the wall structure 3, it is not limited to this structure, and the entire light-emitting element holder 8 can be stored in Between the inner surface 31 and the outer surface 32. The light receiving element holder 9 can be similarly stored between the inner surface 31 and the outer surface 32.

In the first embodiment, although most of the small pieces 30 are integrally formed with the bottom plate 73 so as to protrude from the inner bottom surface 731 of the bottom plate 73, the structure is not limited to this, and most of the small pieces 30 may be separate members from the bottom plate 73. For example, most of the small pieces 30 can be fixed to the bottom plate 73 by adhesion or fitting. In this case, although the majority of the small pieces 30 are scattered, in this case, the majority of the small pieces 30 also 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, a laser diode (LD: Laser Diode), or the like. The light receiving element 5 is not limited to a photodiode, and may be, for example, a photoelectric crystal.

In addition, the lead protruding from the bottom surface 43 or the lead passing through the through hole 801 of the light emitting element holder 8 may be a lead electrically connected to the light emitting element 4, and is not limited to the lead terminal 402, and may be, for example, an electrically connected lead terminal 402. Wires etc.

The pair of lead terminals 402 is not limited to a structure protruding from the bottom surface 43, and may be protruded from a surface other than the bottom surface 43 of the body portion 401 such as the light exit surface 41 or the back surface 42.

In addition, the light-shielding structure 70 may be located on the path of the light output by the light-emitting element 4 and reflected once or more on the inner surface 700 of the sensing case 7 and incident on the light-receiving element 5. Light enters the path of the light receiving element 5.

In addition, the light shielding structure 70 is not limited to a structure that completely shields light, and may be a structure that reduces the amount of light transmitted through the light shielding structure 70.

In addition, the light shielding structure 70 including both the light shielding sheet 802 and the light shielding ribs 75 and 724 is not a necessary structure in the smoke sensor 1, and the light shielding sheet 802 or the light shielding ribs 75 and 724 may be omitted, for example. In addition, when the light-shielding structure 70 includes a light-shielding rib, the light-shielding structure 70 may have light-shielding ribs 75 and 724 protruding from at least one of the inner bottom surfaces of the pair of inner bottom surfaces 731 and 725, or only one of the light-shielding ribs 75 and 724 may be omitted. .

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. In addition, the positions and shapes of the light shielding ribs 75 and 72 in the plan view may be different.

(Embodiment 2)
As shown in FIG. 15, the shape and the like of the wall structure 3 of the smoke sensor 1A of the present embodiment are different from those of the smoke sensor 1 of the first embodiment. Hereinafter, the same configuration as in the first embodiment will be assigned the same reference numerals, and the description will be appropriately omitted.

As shown in FIG. 15, in the plan view, the smoke sensor 1A has 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 side surface 32 of the wall structure 3. In this embodiment, the auxiliary light shielding wall 76 is omitted (see FIG. 7). The shape of each of the plurality of small pieces 30 constituting the wall structure 3 is also different from that of the smoke sensor 1 of the first embodiment. FIG. 15 shows a state where the second casing 72 is removed, that is, a plan view of the sensing block 10 of the second casing 72 is omitted. In FIG. 15, the inner side surface 31 and the outer side surface 32 are indicated by imaginary lines (two dotted lines), and halftone dots (dotted shadows) are added to the area corresponding to the wall structure 3.

In addition, in the smoke sensor 1A, the appearance shape of the light emitting element 4 is also different from that of the smoke sensor 1 of the first embodiment. However, 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 projecting surface (bottom surface 43) of the lead terminal 402 faces 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 exit surface 41 facing the inner side surface 31 side.

FIG. 16 shows a smoke sensor 1B according to a modification of the second embodiment. The wall structure 3 of the smoke sensor 1B shown in FIG. 16 is provided in the second case 72 instead of the first case 71. FIG. 16 shows a state where the second casing 72 is removed, that is, a plan view of the sensing block 10 of the second casing 72 is omitted. Therefore, the wall structure 3 is shown by an imaginary line (two dotted lines) in FIG. 16. In addition, in FIG. 16, the inner side surface 31 and the outer side surface 32 are indicated by imaginary lines (two dotted lines), and halftone dots (dotted shadows) are added to the area corresponding to the wall structure 3. In the example of FIG. 16, the light shielding wall 74 is also provided in the second case 72 together with the wall structure 3. In the smoke sensor 1B having such a structure, in a state where the first case 71 and the second case 72 are coupled to each other, the smoke sensor 1B is arranged in a plan view so as to surround the sensing space Sp1 in the same manner as the smoke sensor 1A.墙 结构 3。 Wall structure 3.

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

(Embodiment 3)
As shown in FIGS. 17A and 17B, the shape of each of the plurality of small pieces 30 constituting the wall structure 3 of the smoke sensor 1C of this embodiment is different from that of the smoke sensor 1A of the second embodiment. In Figs. 17A and 17B, a part of the light output from the light emitting element 4 is schematically shown by a dotted line. FIG. 17B is an enlarged view of a region Z1 in FIG. 17A. In the following, the same configuration as in the second embodiment is assigned the same reference numerals, and description thereof will be appropriately omitted.

As shown in FIG. 17A, in this embodiment, at least a part of the plurality of small pieces 30 is on the surface facing the sensing space Sp1 side, that is, the surface on which the direct light from the light emitting element 4 enters includes a concave curved surface 303. Here, among the plurality of small pieces 30, only the small piece 30 where the direct light from the light emitting element 4 is incident, that is, the small piece 30 located on the substantially front side of the light emitting element 4 has a concave curved surface 303. The concave curved surface 303 is curved into, for example, a part of a parabola or a part of an ellipse in a plan view.

18A and 18B are plan views schematically showing a part of light emitted from the light emitting element 4 in the smoke sensor 1A of the second embodiment with a dotted line. As can be seen from FIGS. 18A and 18B, when the small piece 30 does not have a concave curved surface 303, when a part of the light output by the light emitting element 4 enters any one small piece 30, the light is reflected by the small piece 30. As shown in FIG. 18B, the light reflected by any one of the small pieces 30 is reflected toward the small piece 30 adjacent to the small piece 30. At this time, the small piece 30 forms substantially parallel light with respect to the small piece 30 and the incident light is still reflected as substantially parallel light. As a result, as shown by the passage Op4 in FIGS. 18A and 18B, a part of the light is reflected multiple times by the plurality of small pieces 30 and enters the light receiving element 5 to form a so-called "stray light", which becomes the smoke sensor 1A. Factors that reduce sensing accuracy.

In contrast, according to the smoke sensor 1C of this embodiment, when a part of the light output from the light emitting element 4 enters any one of the small pieces 30, the light is reflected by the concave curved surface 303 of the small piece 30. As shown in FIG. 17B, the light reflected by the concave curved surface 303 of any one of the small pieces 30 is reflected toward the small piece 30 adjacent to the small piece 30. At this time, the concave curved surface 303 acts to condense the light incident on the concave curved surface 303 with substantially parallel light. As a result, the light from the light-emitting element 4 that has entered the small piece 30 can be enclosed between the adjacent pair of small pieces 30. Therefore, the "stray light" incident on the light-receiving element 5 can be reduced compared to the example of Figs. 18A and 18B. ". Therefore, the smoke sensor 1C of this embodiment can suppress the increase in stray light even though the detection accuracy is improved.

As a modification of the third embodiment, at least a part of the plurality of small pieces 30 is on the back surface of the concave curved surface 303, that is, the surface facing the opposite side of the concave curved surface 303 has another (second) concave curved surface. In this structure, the reflected light reflected by the concave curved surface 303 is further condensed by the second concave curved surface, so that the light from the light emitting element 4 incident on the small piece 30 is easily blocked between the adjacent pair of small pieces 30. Therefore, it is possible to further reduce the "stray light" incident on the light receiving element 5, thereby suppressing the increase in stray light even though the sensing accuracy is improved.

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

(Embodiment 4)
As shown in FIG. 19, the light-shielding wall 74 of the smoke sensor 1D of this embodiment has many small walls 741 and 742, which is different from the smoke sensor 1 of the first embodiment in this respect. In FIG. 19, halftone dots (dotted shadows) are added to the light irradiation area A1 of the light emitting element 4 and the light receiving area A2 of the light receiving element 5. The area where the irradiated area A1 and the light-receiving area A2 overlap in the sensing space Sp1 becomes a sensing area A3 which is particularly helpful for smoke sensing. Note that a single light-shielding wall 74 in the first embodiment is shown by an imaginary line (two dotted lines) in FIG. 19. Hereinafter, the same configuration as in the first embodiment will be assigned the same reference numerals, and the description will be appropriately omitted.

In the present embodiment, the light shielding wall 74 includes two small walls 741 and 742 of a (first) small wall 741 and a (second) small wall 742. That is, in plan view, many 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. The plurality of small walls 741 and 742 have a function of shielding direct light from the light emitting element 4 to the light receiving element 5.

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

According to the smoke sensor 1D of this embodiment, in the plan view, it is ensured that 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 cross to the light-shielding wall 74 (small wall 741) , 742). That is, compared with the single light-shielding wall 74 in the first embodiment, most of the small walls 741 and 742 can be arranged at positions far from the center point P1. Therefore, the arrangement degree of the light shielding wall 74 in the sensing space Sp1 is high.

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

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

(Embodiment 5)
As shown in FIGS. 20A and 20B, the shapes of the light emitting side peripheral surface 806 and the light receiving side peripheral surface 903 of the smoke sensor 1E of this embodiment are different from those of the smoke sensor 1 of the first embodiment. Hereinafter, the same configuration as in the first embodiment will be assigned the same reference numerals, and the description will be appropriately omitted.

First, the light emitting side peripheral surface 806 will be described with reference to FIG. 20A. In this embodiment, the light-emitting side peripheral surface 806 is not a paraboloid of rotation but has a flat shape. Therefore, the light emitting side peripheral surface 806 is linear in a plan view. Even if the light emitting side peripheral surface 806 has a flat shape, the light emitting side peripheral surface 806 has a function of converting light output from the light emitting element 4 into light close to parallel light along the optical axis Ax1 of the light emitting element 4.

In addition, the light-receiving-side peripheral surface 903 has a shape formed in a plan view along a parabola Pr2 having the optical axis Ax2 of the light-receiving element 5 as a central axis. The parabola Pr2 is an imaginary line with an intersection (apex) with the optical axis Ax2 as a reference point P12. Therefore, for example, light reflected on the light-receiving-side peripheral surface 903 and incident on the light-receiving element 5 is restricted to light closer to the direction of the optical axis Ax2. Therefore, for example, since the light-receiving portion of the light-receiving element 5 is located on the reference point P12, it is difficult for the light having an inclination with respect to the optical axis Ax2 of the light-receiving element 5 to reach the light-receiving element 5. In addition, if the light receiving portion of the light receiving element 5 is near the focal point of the parabola Pr2, the light incident on the light receiving element 5 after being reflected on the light receiving side peripheral surface 903 is restricted to light closer to the direction of the optical axis Ax2. That is, even light rays having a slight inclination with respect to the optical axis Ax2 of the light receiving element 5 are difficult to reach the light receiving element 5.

In addition, the light-receiving-side peripheral surface 903 may have a shape formed along a paraboloid of revolution with the optical axis Ax2 of the light-receiving element 5 as a central axis. In this case, a surface generated when the parabola Pr2 is rotated around the optical axis Ax2 of the light receiving element 5, that is, the rotating body of the parabola Pr2 forms a light receiving side peripheral surface 903. In this configuration, the light incident on the light receiving element 5 after being reflected on the light-receiving-side peripheral surface 903 in not only the plan view but also in the vertical direction is restricted to light in a direction close to the optical axis Ax2.

The shapes of the light-emitting-side peripheral surface 806 and the light-receiving-side peripheral surface 903 are not limited to the shapes shown in FIGS. 20A and 20B, and can be appropriately changed. The light emitting side peripheral surface 806 may be, for example, a concave curved surface or a convex curved surface other than a rotating paraboloid, as in a free curved surface. The light-receiving-side peripheral surface 903 may be a concave curved surface or a convex curved surface other than the rotating paraboloid, as in a free curved surface.

The structure (including modifications) of the fifth embodiment can be used in appropriate combination with the structure (including modifications) described in the first to fourth embodiments.

(to sum up)
As described above, the first aspect of the smoke sensor (1, 1A to 1E) includes a sensing case (7), a light emitting element (4), a light receiving element (5), and a light emitting element holder (8). The sensing case (7) surrounds the sensing space (Sp1). The light emitting element (4) outputs light to 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 due to the smoke in the sensing space (Sp1) enters. The light emitting element holder (8) holds the light emitting element (4). The sensing housing (7) includes a wall structure (3) that allows smoke to pass and suppresses light transmission. The light emitting element holder (8) has a light emitting guide (84) through which light from the light emitting element (4) passes. The light-emitting guide (84) includes an entrance (805) for opening to the light-emitting element (4), an exit (804) for opening to the sensing space (Sp1), and a peripheral side surface (806). The light emitting side peripheral surface (806) surrounds the optical axis (Ax1) of the light emitting element (4) between the radiation entrance (805) and the radiation exit (804). The light emitting side peripheral surface (806) is inclined toward the radiation exit (804) side with respect to the optical axis (Ax1) of the light emitting element (4).

According to this aspect, when at least a part of the light output by the light-emitting element (4) passes through the light-emitting guide (84), it is reflected on the light-emitting side peripheral surface (806) of the light-emitting guide (84), thereby making light to The inclination of the optical axis (Ax1) of the light-emitting element (4) is reduced. In addition, since the light emitting side peripheral surface (806) is provided in the light emitting element holder (8), the positional relationship between the light emitting side peripheral surface (806) and the light emitting element (4) can be set with relatively high precision, so it is easy to control the light emitting side. The direction of the light reflected by the peripheral surface (806). Therefore, for the light output from the emission port (804) after being reflected on the light emitting side peripheral surface (806), the inclination of the light to the optical axis (Ax1) of the light emitting element (4) can be suppressed to be relatively small. Thereby, the light output from the emission port (804) after being reflected on the light emitting side peripheral surface (806) can reduce the incidence of light entering the light receiving element (5) after being reflected on, for example, the inner surface (700) of the sensing case (7). possibility. As a result, it is difficult for the reflected light on the inner surface (700) of the sensing case (7) to enter the light receiving element (5), so it is possible to improve the sensing accuracy of the smoke sensor (1, 1A to 1E). Suppress the increase of stray light.

The smoke sensor (1, 1A to 1E) of the second aspect is in the first aspect, and the light emitting side peripheral surface (806) is along the center axis of the light axis (Ax1) of the light emitting element (4) Shape formed by rotating a parabola.

According to this aspect, the light closer to the parallel light is output from the emission port (804), so that the reduction in the detection accuracy of the smoke sensor (1, 1A to 1E) can be further suppressed.

The third aspect of the smoke sensor (1, 1A to 1E) is in the first or second aspect, viewed from a direction orthogonal to a plane (inner bottom surface 731 of the bottom plate 73), the wall structure (3 ) Surrounds the sensing space (Sp1). The sensing housing (7) has a pair of inner bottom surfaces (731, 725) and light shielding ribs (75, 724). A pair of inner bottom surfaces (731, 725) face each other in one direction. Viewed from one direction, the light-shielding ribs (75, 724) are arranged at positions overlapping the optical axis (Ax1) of the light-emitting element (4) and protrude from at least one of the inner bottom surfaces of the pair of inner bottom surfaces (731, 725).

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

The fourth aspect of the smoke sensor (1, 1A to 1E) is in the third aspect, and the front end face of the light-shielding rib (75, 724) includes the light axis (Ax1) of the light emitting element (4) and the light emitting element (4) Inclined portions (75a, 724a) inclined on the opposite side.

According to this aspect, the inclined portions (75a, 724a) reflect the light output from the light emitting element (4) in the same way as the light emitting side peripheral surface (806), so that the light can be directed to the optical axis (Ax1) of the light emitting element (4) ) Becomes smaller.

The fifth aspect of the smoke sensor (1, 1A to 1E) is any one of the first to fourth aspects, and further includes a light receiving element holder (9) for holding the light receiving element (5). The light-receiving element holder (9) has a light-receiving guide (92) through which light entering the light-receiving element (5) passes. The light receiving guide (92) includes an introduction port (901) opening into the sensing space (Sp1), an extraction port (902) opening into the light receiving element (5), and a light receiving side peripheral surface (903). The light-receiving-side peripheral surface (903) surrounds the optical axis (Ax2) of the light-receiving element (5) between the introduction port (901) and the extraction port (902). The light-receiving-side peripheral surface (903) is inclined with respect to the optical axis (Ax2) of the light-receiving element (5) toward the guide entrance (901) side.

According to this aspect, when at least a part of the light incident on the light receiving element (5) passes through the light receiving guide (92), it is reflected on the light receiving side peripheral surface (903) of the light receiving guide (92), thereby making the light to The inclination of the optical axis (Ax2) of the light receiving element (5) becomes smaller. In addition, since the light-receiving-side peripheral surface (903) is provided in the light-receiving element holder (9), the positional relationship between the light-receiving-side peripheral surface (903) and the light-receiving element (5) can be set with relatively high precision, so it is easy to control the light-receiving side. The direction of the light reflected by the peripheral surface (903). Therefore, the light incident on the light-receiving element (5) after being reflected on the light-receiving-side peripheral surface (903) can be restricted to light close to the optical axis (Ax2). Thereby, the possibility that the light incident on the introduction port (901) after being reflected on, for example, the inner surface (700) of the sensing case (7), enters the light receiving element (5) after being reflected on the light receiving side peripheral surface (903). Can be lowered. As a result, it is difficult for the reflected light such as the inner surface (700) of the sensing case (7) to enter the light receiving element (5). Therefore, the improvement of the sensing accuracy of the smoke sensor (1, 1A to 1E) is still achieved. Can suppress the increase of stray light.

The sixth aspect of the smoke sensor (1, 1A to 1E) is in the fifth aspect, viewed from a direction orthogonal to a plane (inner bottom surface 731 of the bottom plate 73), the wall structure (3) surrounds the sense Survey space (Sp1). Viewed from one direction, the light-receiving-side peripheral surface (903) has a shape formed along a parabola (Pr2) having the optical axis (Ax2) of the light-receiving element (5) as a central axis.

According to this aspect, the light incident on the light receiving element (5) after being reflected on the light receiving side peripheral surface (903) can be restricted to light closer to the direction of the optical axis (Ax2), so the smoke sensor (1, 1A to 1E).

The seventh aspect of the smoke sensor (1, 1A to 1E) is in the fifth aspect, and the light-receiving side peripheral surface (903) is centered on the light axis (Ax2) of the light-receiving element (5) Shape formed by rotating a parabola.

According to this aspect, the light incident on the light receiving element (5) after being reflected on the light receiving side peripheral surface (903) can be restricted to light closer to the direction of the optical axis (Ax2), so the smoke sensor (1, 1A to 1E).

The second to seventh aspects are not necessary structures in the smoke sensor (1, 1A to 1E), and can be appropriately omitted.

In addition, the structure of the smoke sensor (1, 1A to 1E) in the fifth aspect does not need to be based on the structure of the smoke sensor (1, 1A to 1E) in the first aspect, and may be adopted separately. That is, in the fifth aspect of the smoke sensor (1, 1A to 1E), the light emitting side peripheral surface (806) is not an essential structure, and the light emitting side peripheral surface (806) and the light emitting guide (84) may be appropriately omitted. ) And light-emitting element holder (8).

1, 1A, 1B, 1C, 1D, 1E‧‧‧Smoke sensors

2‧‧‧ frame

3‧‧‧wall structure

4‧‧‧light-emitting element

5‧‧‧ light receiving element

7‧‧‧sensing case

8‧‧‧lighting element bracket

9‧‧‧ light receiving element holder

10‧‧‧ Sensing Block

20‧‧‧Circuit Block

21‧‧‧First cover

22‧‧‧ Second cover

23‧‧‧ opening

30‧‧‧Small

31‧‧‧ inside

32‧‧‧ outside

33‧‧‧ Smoke through the hole

41‧‧‧light exit surface

42‧‧‧ back

43‧‧‧ underside

61‧‧‧Sound output section

62‧‧‧ Battery

63‧‧‧screw

70‧‧‧ Shading structure

71‧‧‧First case

72‧‧‧Second shell

73‧‧‧ floor

74‧‧‧shading wall

75‧‧‧ (first) shading rib

75a, 724a

76‧‧‧Auxiliary shading wall

81‧‧‧First bracket

82‧‧‧Second bracket

83‧‧‧ Luminous holding section

84‧‧‧light guide

91‧‧‧ light receiving section

92‧‧‧light receiving guide

201‧‧‧printed wiring board

202‧‧‧Electronic parts

211‧‧‧The first motherboard

212‧‧‧The first week wall

213‧‧‧Circuit Area

214‧‧‧First sound zone

215‧‧‧ button

216‧‧‧ditch

217‧‧‧Sound hole

221‧‧‧Second motherboard

222‧‧‧Second week wall

223‧‧‧Containment area

224‧‧‧Second Sound Zone

225‧‧‧Battery area

226‧‧‧ divider

301, 302‧‧‧ edge

303‧‧‧Concave surface

401, 501‧‧‧ body

402, 502‧‧‧ lead terminal

403‧‧‧Lighting Department

404‧‧‧Leader

411‧‧‧ flat

412‧‧‧ convex

503‧‧‧metal cover

700‧‧‧ inside

711, 712‧‧‧claw

721‧‧‧ on board

722‧‧‧Zhou Bi

723‧‧‧window

724‧‧‧ (second) light-shielding rib

725‧‧‧ (second) inner bottom

731‧‧‧ (first) inner bottom

741, 742 ‧ ‧ ‧ small wall

801‧‧‧through hole

802‧‧‧shield

803‧‧‧positioning surface

804‧‧‧ Exit

805‧‧‧ Entrance

806‧‧‧ Illuminated side peripheral surface

901‧‧‧ entrance

902‧‧‧ Take exit

903‧‧‧Light-receiving side peripheral surface

Ax1, Ax2‧‧‧ Optical axis

A1‧‧‧ Irradiated area

A2‧‧‧light receiving area

A3‧‧‧Sensing area

C1‧‧‧ Centerline

L1, L2‧‧‧‧ protrusion

Op1, Op2, Op3, Op4, Op5‧‧‧ channels

Pr1, Pr2‧‧‧ Parabola

P1‧‧‧center

P11, P12‧‧‧ benchmark

Sp1‧‧‧ sensing space

Z1‧‧‧ area

q1‧‧‧ half-value angle

FIG. 1A is a cross-sectional view of a main part of a sensing block of a smoke sensor according to Embodiment 1 in a plan view. FIG. 1B is a cross-sectional view showing a main part of a sensing block of the smoke sensor as described above.

FIG. 2A is an external perspective view of the same smoke sensor as viewed obliquely from below. FIG. 2B is an external perspective view of the same smoke sensor as viewed from above.

FIG. 3 is an exploded perspective view of the same smoke sensor as viewed obliquely from below.

FIG. 4 is an exploded perspective view of the same smoke sensor as viewed from above.

FIG. 5 is a partially cutaway perspective view of the same smoke sensor.

FIG. 6 is an exploded perspective view of a sensing block of the smoke sensor.

FIG. 7 is a plan view of the sensing block with the second case removed from the smoke sensor; FIG.

FIG. 8A is a plan view of the sensing block with the second case removed from the smoke sensor; FIG. FIG. 8B shows the main part of the smoke sensor, and is an enlarged view of a region Z1 in FIG. 8A.

FIG. 9 shows the main part of the smoke sensor as described above, and is an enlarged cross-sectional view of a region Z1 in FIG. 5.

FIG. 10 shows the main part of the same smoke sensor, and is an end view along line A1-A1 in FIG. 7.

FIG. 11 is a partially cut-away perspective view of a sensing block of the smoke sensor.

FIG. 12A is a plan view of the main part of the sensing block with the second case removed from the smoke sensor; FIG. Fig. 12B is an end view showing the main part of the smoke sensor as described above.

FIG. 13A is a plan view of the sensing block with the second case removed from the smoke sensor; FIG. FIG. 13B is an enlarged view of a region Z1 in FIG. 13A.

14 is a partially cutaway perspective view of a main part of a sensing block of a smoke sensor according to a modification of the first embodiment.

FIG. 15 is a plan view of the sensing block in the state where the second case is removed from the smoke sensor according to Embodiment 2. FIG.

FIG. 16 is a plan view of a sensing block in a state where a second portion of a smoke sensor is removed from a smoke sensor according to a modification of the second embodiment. FIG.

FIG. 17A is a plan view of a sensing block in a state where a second sensor is removed from a smoke sensor according to Embodiment 3. FIG. FIG. 17B is an enlarged view of a region Z1 in FIG. 17A.

FIG. 18A is a plan view of a sensing block in a state where a second sensor is removed from a smoke sensor according to Embodiment 2. FIG. FIG. 18B is an enlarged view of a region Z1 in FIG. 18A.

FIG. 19 is a plan view of a sensing block in a state where a second sensor is removed from a smoke sensor according to Embodiment 4. FIG.

FIG. 20A is a cross-sectional view showing a main part of a sensing block of a smoke sensor according to Embodiment 5 in a plan view. FIG. FIG. 20B is a plan view showing another main part of the sensing block with the second case removed from the smoke sensor; FIG.

Claims (7)

A smoke sensor includes: A sensing case, which surrounds the sensing space; A light emitting element that outputs light to the sensing space; The light-receiving element is disposed at a position where the direct light from the light-emitting element will not be incident, but the scattered light generated by the smoke in the sensing space will be incident; and Light-emitting element holder to hold light-emitting elements; The sensing housing includes a wall structure that allows the smoke to pass through and suppress light transmission, The light-emitting element holder has a light-emitting guide through which light from the light-emitting element passes, The light-emitting guide includes: an entrance opening that opens to the light-emitting element; an exit opening that opens to the sensing space; and a light-emitting side peripheral surface that surrounds the light-emitting element between the entrance and the exit Optical axis, The light emitting side peripheral surface is inclined with respect to the light axis of the light emitting element toward the emission port side. For example, the smoke sensor of the first patent application scope, wherein the light emitting side peripheral surface has a shape of a rotating parabola along the optical axis of the light emitting element as a central axis. For example, the smoke sensor in the scope of patent application No. 1 or 2, in which: Viewed from a direction orthogonal to a plane, the wall structure surrounds the sensing space, The sensing housing has: A pair of inner bottom faces facing each other in that direction, and The light-shielding rib, viewed from one direction, is arranged at a position overlapping with the optical axis of the light-emitting element and protrudes from at least one inner bottom surface of the pair of inner bottom surfaces. For example, the smoke sensor of claim 3, wherein the front end face of the light-shielding rib includes an inclined portion, and the inclined portion is inclined with respect to the optical axis of the light-emitting element toward a side opposite to the light-emitting element. For example, the smoke sensor in the scope of patent application No. 1 or 2 A light receiving element holder for holding the light receiving element, The light-receiving element holder has a light-receiving guide through which light incident on the light-receiving element passes, The light receiving guide includes: an introduction port that opens to the sensing space; an extraction port that opens to the light receiving element; and a light receiving side peripheral surface that surrounds the light receiving element between the introduction port and the extraction port. Optical axis, The light-receiving-side peripheral surface is inclined toward the introduction port side with respect to the optical axis of the light-receiving element. For example, the smoke sensor under the scope of patent application No. 5 includes: Viewed from a direction orthogonal to a plane, the wall structure surrounds the sensing space, Viewed from the one direction, the light-receiving-side peripheral surface has a shape along a parabola with the optical axis of the light-receiving element as a central axis. For example, the smoke sensor according to item 5 of the application, wherein the light-receiving side peripheral surface has a shape of a rotating parabola along the optical axis of the light-receiving element as a central axis.