JP7829087B2 - smoke detector - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Act (1) Panasonic Corporation Life Solutions Company, April 16, 2021 (2) Toshiba Lighting & Technology Corporation, April 26, 2021 (3) Secom Co., Ltd., April 26, 2021 (4) SMB Building Materials Co., Ltd., May 13, 2021 (5) Emiya Area Partners Co., Ltd., April 28, 2021 (6) Kagoshima Electric Co., Ltd., May 14, 2021 (7) Sekisui Heim Supply Co., Ltd., April 22, 2021 (8) Sekisui Heim Industry Co., Ltd., April 23, 2021 (9) Hagihara Disaster Prevention, April 23, 2021 (10) Material Aid Co., Ltd., April 28, 2021 (11) Mitsuwa Electric Co., Ltd., April 26, 2021 (12) Mu House Engineering Co., Ltd., April 26, 2021 (13) Yamato Financial Co., Ltd., April 28, 2021 (14) Asahi Kasei Homes Corporation, April 22, 2021 (15) Asahi Kasei Reform Corporation, April 22, 2021 (16) Inoue Co., Ltd., May 7, 2021 (17) Inaba Electric Industry Co., Ltd., April 26, 2021 (18) Rycom Co., Ltd., April 23, 2021 (19) Okayama Fire Prevention Management Center Co., Ltd., April 23, 2021 (20) Kibi General Electric Construction Co., Ltd., April 23, 2021 (21) Koden Co., Ltd., April 27, 2021 (22) Sarashina Seisakusho Co., Ltd., May 6, 2021 (23) Hanshin Disaster Prevention Equipment Co., Ltd., May 12, 2021 (24) NTT Facilities Corporation, May 14, 2021 (25) Okada Holdings Co., Ltd., April 28, 2021 (26) Kimura Co., Ltd., May 7, 2021 (27) House Depot Kanto Co., Ltd., April 26, 2021 (28) House LogiCom Co., Ltd., April 26, 2021 (29) Live Life Co., Ltd., April 28, 2021 (30) World Co., Ltd., April 22, 2021 (31) Kyushu Electric Power Co., Ltd., May 7, 2021 (32) Nippon Densho Co., Ltd., April 22, 2021 (33) Meirin Co., Ltd., May 7, 2021 (34) Kyushu Sekisui Heim Industry Co., Ltd., April 23, 2021 (35) Mitsui Home Components Co., Ltd., April 26, 2021 (36) Sanko Lumber Co., Ltd., May 6, 2021 (37) Sanshin Electric Materials Co., Ltd., May 11, 2021

Application of Article 30, Paragraph 2 of the Patent Act (continuation of the preceding paragraph) (38) Mitsubishi Corporation Building Materials Co., Ltd., April 22, 2021 (39) Shikoku Nomi Co., Ltd., April 23, 2021 (40) Shiga Tokki Co., Ltd., May 11, 2021 (41) Sumitomo Forestry Co., Ltd., April 22, 2021 (42) Sumitomo Forestry Home Tech Co., Ltd., April 22, 2021 (43) Kojima Electric Industry Co., Ltd., May 6, 2021 (44) Shinmei Electric Materials Co., Ltd., May 6, 2021 (45) Shoji Electric Co., Ltd., May 10, 2021 (46) Sekisui House, Ltd., May 7, 2021 (47) Chiyoda Electric Materials Co., Ltd., April 26, 2021 (48) Obihiro Disaster Prevention System, May 13, 2021 (49) Daiwa Living Co., Ltd., April 23, 2021 (50) Chugoku Shikoku Sekisui Heim Industry Co., Ltd., May 7, 2021 (51) Chubu Home Service Co., Ltd., April 26, 2021 (52) Tsusho Co., Ltd., May 10, 2021 (53) Tanaka Shoji Co., Ltd., May 14, 2021 (54) Tohoku Sekisui Heim Industry Co., Ltd., April 22, 2021 (55) Nikko Electric Communications Co., Ltd., April 26, 2021 (56) Nisshin Disaster Prevention Co., Ltd., May 7, 2021 (57) Nisshin Shinka Seizo Co., Ltd., April 27, 2021 (58) Nippon Densetsu Shizai Co., Ltd., April 23, 2021 (59) Hokkaido Sekisui Heim Industry Co., Ltd., May 7, 2021 (60) Hokkaido Fire Equipment Co., Ltd., April 23, 2021 (61) CS Disaster Prevention Kagoshima Co., Ltd., May 14, 2021 (62) Chikuhō Tōhatsu Shokai Co., Ltd., May 7, 2021 (63) Nakamura Disaster Prevention Co., Ltd., April 26, 2021 (64) Kansai Minami Kyushu Co., Ltd., April 28, 2021 (65) Kagoshima Denko Co., Ltd., May 7, 2021 (66) Crown Disaster Prevention Co., Ltd., May 14, 2021 (67) Japan Disaster Prevention Equipment Co., Ltd., April 16, 2021 (68) Central Disaster Prevention Co., Ltd., April 21, 2021 (69) Toshin Electric Co., Ltd., May 6, 2021 (70) Nishimura Co., Ltd., May 12, 2021 (71) Nittan Co., Ltd., April 22, 2021 (72) Yamato Protec Co., Ltd., April 27, 2021 (73) Asahi Electric Co., Ltd., April 2, 2021 (74) Inaba Electric Industry Co., Ltd., May 7, 2021 (75) Okuyama Disaster Prevention Co., Ltd., May 6, 2021

Application of Article 30, Paragraph 2 of the Patent Act (continuation of the preceding paragraph) (76) Okada Electric Industry Co., Ltd., May 13, 2021 (77) Okano Co., Ltd., May 12, 2021 (78) General Trading Co., Ltd., May 12, 2021 (79) Minakami Co., Ltd., April 14, 2021 (80) Kyodensha Co., Ltd., May 10, 2021 (81) Kodensha Co., Ltd., May 10, 2021 (82) Yamamoto Trading Co., Ltd., May 14, 2021 (83) Daikyo Disaster Prevention Co., Ltd., April 16, 2021 (84) Nippon Densho Co., Ltd., April 5, 2021 (85) Hokkaido Morita Co., Ltd., April 9, 2021 (86) F.S.K Kiso Disaster Prevention Equipment Co., Ltd., May 13, 2021 (87) Actus Equipment Co., Ltd., May 6, 2021 (88) Takeden Co., Ltd., April 27, 2021 (89) Prosus Co., Ltd., April 22, 2021 (90) World Co., Ltd., April 5, 2021 (91) Ogiko Electric Co., Ltd., April 9, 2021 (92) Hokuriku Denki Shokai Co., Ltd., May 7, 2021 (93) Kyushu Nomi Co., Ltd., April 2, 2021 (94) Shikoku Nomi Co., Ltd., April 2, 2021 (95) Shin-Etsu Shoji Co., Ltd., May 12, 2021 (96) Niigata Nomi Co., Ltd., May 11, 2021 (97) Sema Disaster Prevention Equipment Co., Ltd., May 7, 2021 (98) Chiba Nomi Co., Ltd., April 2, 2021 (99) Comprehensive Disaster Prevention Nakatech, May 6, 2021 (100) Omuro Disaster Prevention Co., Ltd., May 11, 2021 (101) Chuo Disaster Prevention System Co., Ltd., May 7, 2021 (102) Chuo Rika Kogyo Co., Ltd., April 21, 2021 (103) Chukyo Disaster Prevention Industry Co., Ltd., May 14, 2021 (104) Tanaka Shoji Co., Ltd., May 13, 2021 (105) Toho Disaster Prevention Industry Co., Ltd., April 8, 2021 (106) Nissho Setsei Kogyo Co., Ltd., April 28, 2021 (107) Nissin Disaster Prevention Co., Ltd., May 7, 2021 (108) Hitachi Sogo Disaster Prevention Co., Ltd., May 12, 2021 (109) Fukushima Disaster Prevention Co., Ltd., May 7, 2021 (110) Toyota Disaster Prevention, May 7, 2021 (111) Hokkaido Dry Chemical Co., Ltd., April 15, 2021 (112) Ohashi Disaster Prevention Co., Ltd., May 10, 2021 (113) Miyazaki General Communications Systems Co., Ltd., May 7, 2021

This invention relates to a smoke detector.

Conventionally, scattered light type smoke detectors are known (see, for example, Patent Document 1). Scattered light type smoke detectors generally consist of a dark box and a pair of light-emitting and light-receiving elements. Smoke entering the dark box scatters the light from the light-emitting elements, and the scattered light is received by the light-receiving elements, thereby detecting a fire.

Japanese Patent Publication No. 2019-175501

Insects such as spiders can sometimes enter these smoke detectors. When an insect enters the smoke detector and enters its dark box, the light emitted by the light-emitting element may be scattered, and this scattered light may be received by the light-receiving element. If this light is received by the light-receiving element, a fire may be detected even if no fire is actually occurring. Another possibility is that the insect interferes with the emission of light from the light-emitting element or the reception of light by the light-receiving element, resulting in the detection of a fire even though one is actually present.

This invention has been made in view of these circumstances, and aims to reduce the possibility of false fire alarms or missed fire detections caused by insect intrusion.

To solve the above problems, the smoke detector according to the present invention comprises a main base plate and a substrate disposed substantially parallel to the main base plate below the main base plate. The main base plate has a cylindrical wall provided on its lower surface, forming a smoke detection space, and a first rib whose ends are connected to the outer surface of a first wall portion constituting the cylindrical wall, forming a light-receiving unit housing space between the rib and the first wall portion. The first rib extends from the lower surface of the main base plate toward the substrate to prevent insects from entering the light-receiving unit housing space. The substrate has its ends in contact with or close to the outer surface of the first wall portion and covers the light-receiving unit housing space. The upper surface of the substrate is equipped with a light-emitting unit that irradiates light into the smoke detection space, and a light-receiving unit housed in the light-receiving unit housing space, which receives light scattered by smoke particles after being irradiated from the light-emitting unit, through a first light-passing hole formed in the first wall portion.

According to this invention, the possibility of false fire alarms or missed fire detections due to insect intrusion can be reduced.

Bottom view of smoke detector 100 Side view of smoke detector 100 Plan view of smoke detector 100 Exploded perspective view of smoke detector 100 Cross-sectional view along line A-A in Figure 3 Bottom view of the main base plate 1 Lower perspective view of the main base plate 1 Lower perspective view of the main base plate 1 Bottom view of circuit board 2 Plan view of circuit board 2 Bottom perspective view of substrate 2 Bottom view of the circuit board 2 and speaker 3 attached to the main base plate 1. Side view of the circuit board 2 and speaker 3 attached to the main base plate 1. Enlarged view of section B in Figure 12 Bottom view of the middle plate 4 Lower perspective view of the middle plate 4 Plan view of the middle plate 4 Plane perspective view of the middle plate 4 Bottom view of the middle plate 4 attached to the main base plate 1. Side view of the middle plate 4 attached to the main base plate 1. Cross-sectional view along line C-C in Figure 20 Enlarged view of section D in Figure 21 Bottom view of the main body cover 5 Side view of the main body cover 5 Plan view of the main body cover 5 Cross-sectional view along line E-E in Figure 3 Bottom view of the main base plate 1A Top perspective view of intermediate plate 4A Vertical cross-sectional view of smoke detector 100A

1. Embodiment 1-1. Configuration of Smoke Detector 100 A smoke detector 100 according to one embodiment of the present invention will be described with reference to Figures 1 to 5. Figures 1 to 4, which are referenced in this description, are a bottom view, a side view, a top view, and an exploded perspective view of the smoke detector 100. Figure 5 is a cross-sectional view taken along line A-A in Figure 3.

As shown in particular in Figures 4 and 5 of these diagrams, the smoke detector 100 consists of a circular main base plate 1, a roughly L-shaped circuit board 2 and a circular speaker 3 positioned roughly parallel to the main base plate 1, a roughly circular intermediate plate 4 positioned roughly parallel to the circuit board 2, and a bottomed cylindrical main cover 5 fixed to the main base plate 1 while housing the main base plate 1, circuit board 2, speaker 3, and intermediate plate 4. The individual components of this smoke detector 100 will be described in order below.

1-2. Configuration of the Main Base Plate 1 First, the main base plate 1 will be described with reference to Figures 6 to 8. In this description, Figure 6 is a bottom view of the main base plate 1, and Figures 7 and 8 are bottom perspective views from different viewpoints.

As shown in these figures, the main base plate 1 has a battery housing 101 formed from its center to its periphery. This battery housing 101 is convex on the lower side of the main base plate 1 and concave on the upper side, with a cylindrical battery housed in the concave upper side. The battery housed in this battery housing 101 is connected to the circuit board 2 and supplies power to the circuit on the circuit board 2.

Furthermore, the main body base plate 1 has a speaker housing 102 formed adjacent to the battery housing 101. This speaker housing 102 is a roughly C-shaped rib that protrudes vertically from the lower surface of the main body base plate 1. The speaker 3 is housed in this speaker housing 102.

The speaker housing 102 has a hook 1021 on its outer circumferential surface. This hook 1021 is locked into a locking hole 422 (see Figure 18) in the intermediate plate 4, which will be described later.

Furthermore, the main base plate 1 has a cylindrical wall 103 formed on the axis of the battery housed in the battery compartment 101. This cylindrical wall 103 is an isosceles trapezoidal rib that protrudes vertically from the lower surface of the main base plate 1. The lower end of this cylindrical wall 103 abuts against the upper surface of the middle plate 4, forming a smoke detection space.

This cylindrical wall 103 is composed of four linear wall sections 1031, 1032, 1033, and 1034. Of these, wall section 1033 has a light-passing hole 1035 for the light-emitting section 205 (described later) to irradiate the smoke detection space with light. Wall section 1034 has a light-passing hole 1036 for the light-receiving section 206 (described later) to receive light from the smoke detection space.

Furthermore, the main body base plate 1 has a roughly U-shaped rib 104 whose ends are connected to the outer surface of the wall portion 1033. This rib 104 forms a space for housing the light-emitting unit between itself and the wall portion 1033.

This rib 104 extends vertically from the lower surface of the main body base plate 1 toward the substrate 2, and contacts the upper surface of the substrate 2, in order to prevent insects from entering the light-emitting section housing space.

Furthermore, the main body base plate 1 has a U-shaped rib 105 whose ends are connected to the outer surface of the wall portion 1034. This rib 105 forms a light-receiving unit housing space between itself and the wall portion 1034.

This rib 105 extends vertically from the underside of the main body base plate 1 toward the substrate 2 to prevent insects from entering the light-receiving compartment. There is a small gap between this rib 105 and the substrate 2, but this gap is approximately the same size as the mesh of the insect-proof screen ring 6 (see Figure 4), which will be described later. In other words, it is a size that prevents insects from passing through.

Furthermore, the main base plate 1 has a substrate mounting portion 106. This substrate mounting portion 106 is a rib that protrudes vertically from the lower surface of the main base plate 1 and is formed to surround a roughly L-shaped area. The peripheral edge of the upper surface of the substrate 2 is attached to this substrate mounting portion 106.

This substrate mounting portion 106 has two hooks 1061 and 1062 on its outer surface. These two hooks 1061 and 1062 are locked into locking holes 423 and 424 (see Figure 18) of the intermediate plate 4, which will be described later.

Furthermore, the main body base plate 1 has two recessed portions 107A and 107B formed on the side opposite the speaker housing 102, flanking the battery housing 101. These two recessed portions 107A and 107B are rod-shaped members formed by creating U-shaped through grooves in the main body base plate 1.

Of these two push-in parts 107A and 107B, push-in part 107A is positioned to contact the registration switch 209 (described later), and when push-in part 107A is pressed by the user, the registration switch 209 is pressed. On the other hand, push-in part 107B is positioned to contact the erase switch 210 (described later), and when push-in part 107B is pressed by the user, the erase switch 210 is pressed.

The main base plate 1 also has two columnar antenna holding portions 108 and 109 that protrude vertically from its periphery. Of these two antenna holding portions 108 and 109, antenna holding portion 108 is positioned adjacent to the outer surface of the substrate mounting portion 106. This antenna holding portion 108 is inserted into the insertion hole 416 (see Figure 15) of the intermediate plate 4, which will be described later. Furthermore, a U-shaped groove is formed at the tip of this antenna holding portion 108, into which the antenna 212 is fitted.

On the other hand, the antenna holder 109 is positioned on the axis of the battery housed in the battery housing 101. This antenna holder 109 is inserted through the locking hole 425 (see Figure 15) of the intermediate plate 4, which will be described later. Furthermore, a U-shaped groove is formed at the tip of the antenna holder 109, into which the antenna 212 is fitted.

Furthermore, the antenna holder 109 has a hook 1091 on its outer surface (in other words, the surface opposite to the surface facing the cylindrical wall 103). This hook 1091 is locked into a locking hole 425 (see Figure 15) in the intermediate plate 4, which will be described later.

Furthermore, the main body base plate 1 has a pair of plate-shaped switch holding portions 110 and 111 that protrude vertically from its peripheral edge. These switch holding portions 110 and 111 hold the illuminated switch 8, which will be described later.

Of the pair of switch holders 110 and 111, the switch holder 110 has a U-shaped groove and a U-shaped groove formed at its tip. The shaft of the illuminated switch 8 is fitted into the U-shaped groove, and the antenna 212 is fitted into the U-shaped groove. On the other hand, the switch holder 111 has a U-shaped groove formed at its tip. The shaft of the illuminated switch 8 is fitted into this U-shaped groove.
The above is a description of the main base plate 1.

1-3. Configuration of Substrate 2 Next, the substrate 2 will be described with reference to Figures 9 to 11. Figures 9 to 11, which will be referenced in this description, are the bottom view, top view, and bottom perspective view of the substrate 2.

As shown in these figures, the substrate 2 has a fan-shaped notch 201 with a central angle approximately right-angle. The battery housing 101 of the main base plate 1 and the speaker 3 are positioned in the area where this notch 201 is formed. The speaker 3 positioned in this area is connected to the substrate 2.

Furthermore, the substrate 2 has an isosceles trapezoidal notch 202. The cylindrical wall 103 of the main base plate 1 is positioned in the region where this notch 202 is formed.

Furthermore, the substrate 2 has a pair of rectangular notches 203 and 204 facing each other, with an isosceles trapezoidal notch 202 in between.

Furthermore, a light-emitting unit 205 is mounted on the upper surface of the substrate 2. This light-emitting unit 205 is, for example, a light-emitting diode. This light-emitting unit 205 is housed in a light-emitting unit housing space formed by the cylindrical wall 103 and ribs 104 of the main base plate 1, and irradiates light into the smoke detection space formed by the cylindrical wall 103. At that time, the light-emitting unit 205 irradiates light into the smoke detection space through the light-passing holes 1035 of the cylindrical wall 103.

Furthermore, a light-receiving unit 206 is mounted on the upper surface of the substrate 2. This light-receiving unit 206 is, for example, a photodiode housed in a shielding case. This light-receiving unit 206 is housed in a light-receiving unit housing space formed by the cylindrical wall 103 and ribs 105 of the main base plate 1, and receives light from the light-emitting unit 205 scattered upon contact with smoke particles. At that time, the light-receiving unit 206 receives this scattered light through the light-passing holes 1036 in the cylindrical wall 103.

The light-emitting section 205 and the light-receiving section 206 are arranged along the isosceles trapezoidal notch 202 so that their respective optical axes are not on the same straight line.

Furthermore, a test switch 207 and an indicator light 208 are mounted on the underside of circuit board 2. The test switch 207 is used to test the internal circuitry and battery life. This test switch 207 is pressed when the illumination switch 8 (described later) is pressed. The indicator light 208, on the other hand, is an LED used to indicate the results of the test.

Furthermore, a registration switch 209 and an erase switch 210 are mounted on the top surface of circuit board 2. The registration switch 209 is used to set the wireless channel used by the smoke detector 100, and the erase switch 210 is used to erase the wireless channel setting.

Furthermore, a connector 211 is mounted on the top surface of circuit board 2.

Furthermore, an antenna 212 made of metal wire is connected to the substrate 2. This antenna 212 consists of a straight portion 2121 and an arc portion 2122. One end of the straight portion 2121 is connected to a wireless communication circuit 215 (not shown), extends vertically from the bottom surface of the substrate 2, and is inserted into the antenna hole 420 (see Figure 15) of the middle plate 4. On the other hand, one end of the arc portion 2122 is connected to the other end of the straight portion 2121, and extends in an arc shape to surround the isosceles trapezoidal notch 202.

Furthermore, a conductor 213 made of metal wire is connected to the circuit board 2. This conductor 213 is composed of a straight portion 2131 and an arc portion 2132. One end of the straight portion 2131 is connected to the ground (not shown) on the circuit board 2, and it extends along the longitudinal direction of the battery housing 101. On the other hand, one end of the arc portion 2132 is connected to the other end of the straight portion 2131, and it extends in an arc shape to surround the speaker 3.

Furthermore, circuit board 2 is equipped with a control circuit 214 (not shown). This control circuit 214 performs fire detection processing, fire signal transmission processing, and wireless channel setting processing, which will be described later.

The circuit board 2 also has a wireless communication circuit 215 (not shown) mounted on it. This wireless communication circuit 215 uses an antenna 212 to communicate wirelessly with other smoke detectors 100 and relay devices.
The above is a description of circuit board 2.

The circuit board 2 described above has its upper edge attached to the circuit board mounting portion 106 of the main base plate 1. The speaker 3, connected to the circuit board 2, is fitted into the speaker housing portion 102 of the main base plate 1. Figures 12 and 13 are the bottom and side views, respectively, of the circuit board 2 and speaker 3 attached to the main base plate 1 in this manner. Figure 14 is an enlarged view of portion B in Figure 12.

As shown in Figure 12 in particular, the battery housing 101 of the main base plate 1 is located in the region where the fan-shaped notch 201 is formed in the substrate 2. Furthermore, the cylindrical wall 103 of the main base plate 1 is located in the region where the isosceles trapezoidal notch 202 is formed in the substrate 2. The notch 202 of the substrate 2 abuts against the outer surface of this cylindrical wall 103.

More specifically, as shown in Figure 14, the notch 202 abuts against the outer surfaces of wall portions 1031, 1033, and 1034, which are among the four wall portions 1031 to 1034 that constitute the cylindrical wall 103. Therefore, the substrate 2 covers the light-emitting unit housing space and the light-receiving unit housing space formed in the main base plate 1. Furthermore, the rectangular notch 203 of the substrate 2 forms a through-hole 216 between it and wall portion 1033. This through-hole 216 connects the space between the substrate 2 and the intermediate plate 4 to the light-emitting unit housing space. Similarly, the rectangular notch 204 of the substrate 2 forms a through-hole 217 between it and wall portion 1034. This through-hole 217 connects the space between the substrate 2 and the intermediate plate 4 to the light-receiving unit housing space.

Furthermore, as shown in Figure 12, the antenna 212 connected to the circuit board 2 is held in place by the antenna holding portions 108 and 109 of the main body base plate 1 and a U-shaped groove formed at the tip of the switch holding portion 110.

1-4. Structure of the Intermediate Plate 4 Next, the intermediate plate 4 will be described with reference to Figures 15 to 18. Figures 15 to 18, which will be referenced in this description, are a bottom view, a bottom perspective view, a top view, and a top perspective view of the intermediate plate 4.

As shown in these figures, the middle plate 4 has a roughly U-shaped notch 401 formed from its center to its periphery. The battery housing 101 of the main base plate 1 is positioned in the area where this notch 401 is formed.

Furthermore, the intermediate plate 4 has an elliptical ventilation hole 402 formed on the opposite side of the notch 401, with the center of the plate in between. This ventilation hole 402 connects the space between the intermediate plate 4 and the main body cover 5 with the smoke detection space formed in the main body base plate 1.

Furthermore, the intermediate plate 4 has three labyrinth walls 403-405 formed around the ventilation holes 402. These three labyrinth walls 403-405 are plate-like walls that protrude vertically from the lower surface of the intermediate plate 4. These three labyrinth walls 403-405 are formed so as not to obstruct the inflow of smoke into the ventilation holes 402, while simultaneously obstructing the incidence of external light into the ventilation holes 402.

Furthermore, the intermediate plate 4 has a pair of rectangular locking holes 406 and 407 formed around the labyrinth walls 403 to 405. These locking holes 406 and 407 are for the hooks of the optical table cover 7 (see Figure 4), which will be described later.

Furthermore, the intermediate plate 4 has eight antenna holding sections 408-415 that are radially formed around the labyrinth walls 403-405. These eight antenna holding sections 408-415 are substantially straight plates that protrude vertically from the lower surface of the intermediate plate 4. Each of these eight antenna holding sections 408-415 has a notch at its tip, into which the antenna 212 is fitted.

Furthermore, the middle plate 4 has a rectangular through-hole 416 formed on its periphery. The antenna holding portion 108 of the main base plate 1 is inserted through this through-hole 416.

Furthermore, the middle plate 4 has a plurality of speaker holes 417 formed adjacent to the U-shaped notch 401. These speaker holes 417 are located below the speaker 3.

The middle plate 4 also has a switch hole 418 and an indicator hole 419 formed adjacent to the U-shaped notch 401. Of these holes, the switch hole 418 is a through-hole through which the inspection switch 207 is inserted. On the other hand, the indicator hole 419 is a light-passing hole for allowing light from the indicator light 208 to pass through.

Furthermore, the middle plate 4 has an antenna hole 420 formed on its peripheral edge. This antenna hole 420 is a through-hole through which the antenna 212 is inserted.

Furthermore, the intermediate plate 4 has side walls 421 erected on the peripheral edge of its upper surface.

Furthermore, the middle plate 4 has three rectangular locking holes 422 to 424 formed in the side wall 421. Of these three locking holes 422 to 424, the hook 1021 of the main base plate 1 is locked into locking hole 422, the hook 1061 of the main base plate 1 is locked into locking hole 423, and the hook 1062 of the main base plate 1 is locked into locking hole 424.

The intermediate plate 4 also has a locking hole 425 formed from its peripheral edge to the side wall 421. As shown in Figure 16, this locking hole 425 is positioned to sandwich the labyrinth wall 404 between it and the ventilation hole 402. This locking hole 425 is constructed by connecting a rectangular hole formed on the peripheral edge and a rectangular hole formed on the side wall 421. The antenna holding portion 109 of the main base plate 1 is inserted through the former hole. The hook 1091 of the main base plate 1 is locked into the latter hole.

Furthermore, the intermediate plate 4 has a partition wall 426 that separates the ventilation hole 402 and the locking hole 425, with both ends of the partition wall 426 connected to the side wall 421. This partition wall 426 is a plate that protrudes vertically from the upper surface of the intermediate plate 4.

Furthermore, the intermediate plate 4 has a pair of ribs 427 and 428 formed to surround the ventilation holes 402 together with the partition wall 426. These ribs 427 and 428 are formed to extend approximately perpendicularly from the upper surface of the intermediate plate 4 toward the substrate 2. There is a small gap between these ribs 427 and 428 and the substrate 2, but this gap is approximately the same size as the mesh of the insect-proof screen ring 6 (see Figure 4), which will be described later. In other words, it is a size that inhibits the passage of insects.

Of this pair of ribs 427 and 428, rib 427 is composed of a straight portion 4271 with one end connected to the partition wall 426, a U-shaped portion 4272 with one end connected to the other end of the straight portion 4271, and a straight portion 4273 with one end connected to the other end of the U-shaped portion 4272. On the other hand, rib 428 is composed of a straight portion 4281 with one end connected to the partition wall 426, and a U-shaped portion 4282 with one end connected to the other end of the straight portion 4281. The lower end of the cylindrical wall 103 of the main body base plate 1 is fitted into the space formed by this pair of ribs 427 and 428 and the partition wall 426.
The above is an explanation of the middle plate 4.

The intermediate plate 4 described above is attached to the main base plate 1 so as to cover the circuit board 2 and the speaker 3. At this time, the hooks 1021, 1061, 1062, and 1091 of the main base plate 1 engage with the locking holes 422 to 425 of the intermediate plate 4, thereby fixing the intermediate plate 4 to the main base plate 1. Figures 19 and 20 are the bottom and side views, respectively, of the intermediate plate 4 attached to the main base plate 1 in this manner. Figure 21 is a cross-sectional view taken along line C-C in Figure 20. Figure 22 is an enlarged view of section D in Figure 21.

As shown in Figure 19 in particular, the battery housing 101 of the main base plate 1 is located in the area where the notch 401 of the middle plate 4 is formed. The antenna holding portion 108 of the main base plate 1 is inserted through the insertion hole 416 of the middle plate 4. The antenna holding portion 109 of the main base plate 1 is inserted through the locking hole 425 of the middle plate 4. The antenna 212 is inserted through the antenna hole 420 of the middle plate 4. The antenna 212 inserted through the antenna hole 420 is fitted into the notches of the antenna holding portions 408-415 of the middle plate 4. The inspection switch 207 is inserted through the switch hole 418 of the middle plate 4. The indicator light 208 is visible through the display hole 419 of the middle plate 4.

Furthermore, as shown in Figure 22 in particular, the lower end of the cylindrical wall 103 of the main base plate 1 is fitted into the space formed by the partition wall 426 of the intermediate plate 4 and the pair of ribs 427 and 428. As a result, the partition wall 426 of the intermediate plate 4 abuts against the outer surfaces of the wall portions 1032 to 1034 that constitute the cylindrical wall 103. Also, the ribs 427 of the intermediate plate 4 abut against the outer surfaces of the wall portions 1031 and 1034 that constitute the cylindrical wall 103. In particular, the U-shaped portion 4272 of the rib 427 has both ends abutting against the outer surfaces of the wall portion 1034, surrounding the through hole 217. In addition, the upper end of this U-shaped portion 4272 is close enough to the substrate 2 to obstruct the passage of insects. Therefore, this U-shaped portion 4272 obstructs the entry of insects into the through hole 217 in the space between the intermediate plate 4 and the substrate 2.

Furthermore, the ribs 428 of the intermediate plate 4 abut against the outer surface of the wall portion 1033 that constitutes the cylindrical wall 103. In particular, the U-shaped portion 4282 of the rib 428 abuts against the outer surface of the wall portion 1033 at both ends, surrounding the through-hole 216. In addition, the upper end of this U-shaped portion 4282 is close enough to the substrate 2 to obstruct the passage of insects. Therefore, this U-shaped portion 4282 prevents insects from entering the through-hole 216 in the space between the intermediate plate 4 and the substrate 2.

1-5. Structure of the Main Body Cover 5 Next, the main body cover 5 will be described with reference to Figures 23 to 25. Figures 23 to 25, which will be referenced in this description, are the bottom view, side view, and top view of the main body cover 5.

As shown in Figure 23 in particular, the main body cover 5 has an oval-shaped switch hole 501 formed in its bottom plate. An illuminated switch 8 (see Figure 4) is fitted into this switch hole 501.

Furthermore, as shown in Figure 24, the main body cover 5 has a plurality of ventilation holes 502 formed on the lower side of its cylindrical portion. These ventilation holes 502 are for allowing smoke to flow into the space between the main body cover 5 and the intermediate plate 4.

Furthermore, as shown in Figure 25, the main body cover 5 has a pair of switch support portions 503A and 503B formed adjacent to the switch hole 501. These switch support portions 503A and 503B have U-shaped notches into which the shaft portion of the illuminated switch 8 is fitted.
The above is a description of the main body cover 5.

The main body cover 5, as described above, is fixed to the main body base plate 1 while housing the main body base plate 1, circuit board 2, speaker 3, and intermediate plate 4 (see Figure 4). At this time, an insect screen ring 6 is attached to the intermediate plate 4 housed in the main body cover 5. More specifically, this insect screen ring 6 is attached so as to surround the ventilation holes 402 and labyrinth walls 403-405 of the intermediate plate 4.

Next, the optical bench cover 7 is attached so as to cover the lower opening of the insect screen ring 6. This optical bench cover 7 has a disc portion, a star-shaped projection formed in the center of the upper surface of the disc portion, and a pair of hooks erected on the periphery of the disc portion. When this optical bench cover 7 is attached to the middle plate 4, its disc portion covers the lower opening of the insect screen ring 6, its projection is inserted between the labyrinth walls 403-405 of the middle plate 4, and its pair of hooks are locked into a pair of locking holes 406 and 407 of the middle plate 4.

In addition, an illuminated switch 8 is mounted on the main body base plate 1, which is housed in the main body cover 5. This illuminated switch 8 has an oval-shaped plate portion, a projection extending vertically from one end of the plate portion, a columnar portion erected vertically at the other end of the plate portion, and a shaft portion formed at the base end of the columnar portion. Furthermore, this illuminated switch 8 is made of a translucent resin material containing a light-diffusing agent. When this illuminated switch 8 is mounted on the main body base plate 1, its projection portion contacts the inspection switch 207 on the circuit board 2, its columnar portion is inserted between a pair of switch holders 110 and 111 on the main body base plate 1, and its shaft portion is fitted into the U-shaped grooves of the pair of switch holders 110 and 111.

As described above, after attaching the insect screen ring 6, optical bench cover 7, and illumination switch 8, the main body cover 5 is attached to the main body base plate 1. Once the main body cover 5 is attached to the main body base plate 1, the plate portion of the illumination switch 8 is fitted into its switch hole 501. In addition, the shaft portion of the illumination switch 8 is held between the pair of switch support portions 503A and 503B of the main body cover 5 and the pair of switch holding portions 110 and 111 of the main body base plate 1.

1-6. Function Next, the function of the ribs 105 of the main base plate 1 will be explained.
As shown in Figure 7, the rib 105 of the main body base plate 1 is a U-shaped rib whose both ends are connected to the outer surface of the cylindrical wall 103. In addition, as shown in Figure 13, the lower end of this rib 105 is close enough to the substrate 2 to obstruct the passage of insects. Therefore, this rib 105 prevents insects from entering the light-receiving unit housing space formed between the rib and the cylindrical wall 103.

The main base plate 1 has indentation portions 107A and 107B as described above (see Figure 6). A U-shaped through groove is formed around these indentation portions 107A and 107B, and insects may enter the device through this U-shaped through groove. If an insect enters the device, it may travel between the main base plate 1 and the substrate 2 and reach the vicinity of the light-receiving portion 206. Assuming the absence of the rib 105, the insect may enter the optical axis of the light-receiving portion 206, potentially obstructing its light reception. If the light-receiving portion 206 is obstructed, it will be impossible to detect a fire even if one occurs. Another possibility is that the insect may enter the smoke detection space through the light-passing hole 1036. If it enters the smoke detection space, the light from the light-emitting portion 205 may hit the insect, scatter, and be received by the light-receiving portion 206. If scattered light is received by the light-receiving unit 206, a fire will be detected even though no fire is actually occurring.

In contrast, the presence of the rib 105 prevents insects from entering the light-receiving unit's housing space. Therefore, the possibility of false alarms or missed fire detections due to insect intrusion can be reduced.

Next, the function of the ribs 427 of the intermediate plate 4 will be explained.
As shown in Figure 22, the rib 427 of the intermediate plate 4 has a U-shaped portion 4272. This U-shaped portion 4272 is a U-shaped rib that surrounds the through hole 217, with both ends abutting against the outer surface of the cylindrical wall 103. In addition, the upper end of this U-shaped portion 4272 is close enough to the substrate 2 to obstruct the passage of insects. Therefore, this U-shaped portion 4272 prevents insects from entering the through hole 217 in the space between the intermediate plate 4 and the substrate 2.

The main body cover 5 has ventilation holes 502 as described above (see Figure 24). The middle plate 4 also has display holes 419 as described above (see Figure 15). Insects may enter the space between the middle plate 4 and the substrate 2 through these ventilation holes 502 and display holes 419. If insects enter that space, they may travel through that space and reach the vicinity of the through-hole 217. In that case, assuming that the U-shaped portion 4272 is not present, the insects may enter the light-receiving unit housing space through the through-hole 217. If the insects enter the light-receiving unit housing space, they may obstruct the light reception of the light-receiving unit 206. If the light reception of the light-receiving unit 206 is obstructed, even if a fire occurs, it will not be possible to detect the fire. Another possibility is that the insects may enter the smoke detection space through the light-passing hole 1036. If an insect enters the smoke detection area, the light from the light-emitting unit 205 may hit the insect, scatter, and be received by the light-receiving unit 206. If scattered light is received by the light-receiving unit 206, a fire may be detected even if no fire is actually occurring.

In contrast, the presence of the U-shaped portion 4272 prevents insects from entering the through-hole 217. Therefore, the possibility of false alarms or missed fire detections due to insect intrusion can be reduced.

Next, the function of the ribs 428 of the intermediate plate 4 will be explained.
As shown in Figure 22, the rib 428 of the intermediate plate 4 has a U-shaped portion 4282. This U-shaped portion 4282 is a U-shaped rib that surrounds the through hole 216, with both ends of the rib contacting the outer surface of the cylindrical wall 103. In addition, the upper end of this U-shaped portion 4282 is close enough to the substrate 2 to obstruct the passage of insects. Therefore, this U-shaped portion 4282 prevents insects from entering the through hole 216 in the space between the intermediate plate 4 and the substrate 2.

The main body cover 5 has ventilation holes 502 as described above (see Figure 24). The middle plate 4 also has display holes 419 as described above (see Figure 15). Insects may enter the space between the middle plate 4 and the substrate 2 through these ventilation holes 502 and display holes 419. If an insect enters that space, it may travel through that space and reach the vicinity of the through hole 216. In that case, assuming that the U-shaped portion 4282 is not present, the insect may enter the light-emitting unit housing space through the through hole 216. If the insect enters the light-emitting unit housing space, it may obstruct the emission of light from the light-emitting unit 205. If the emission of light from the light-emitting unit 205 is obstructed, even if a fire occurs, it will not be detected. Another possibility is that the insect enters the smoke detection space through the light-passing hole 1035. If the insect enters the smoke detection space, the light from the light-emitting unit 205 may hit the insect, scatter, and be received by the light-receiving unit 206. If scattered light is received by the light-receiving unit 206, a fire will be detected even though no fire is actually occurring.

In contrast, the presence of the U-shaped portion 4282 prevents insects from entering the through-hole 216. Therefore, the possibility of false alarms or missed fire detections due to insect intrusion can be reduced.

Next, the function of forming the hook 1091 on the antenna holding portion 109 of the main base plate 1 will be explained with reference to Figure 26. Figure 26, which will be referenced in this explanation, is a cross-sectional view taken along line E-E in Figure 3. Note that hatching has been omitted in Figure 26 to prevent the drawing from becoming difficult to read.

As shown in the figure, a cutting hole 112 is formed directly above the hook 1091. This cutting hole 112 is formed when the main body base plate 1 is molded. If an insect enters this cutting hole 112, it may pass between the inner surface of the main body cover 5 and the outer surface of the middle plate 4, as shown by arrow A1 in the figure, and reach the space between the upper surface of the main body cover 5 and the lower surface of the middle plate 4. However, even if it reaches that space, it will be blocked by the insect screen ring 6 and will not be able to enter the smoke detection space.

In contrast, let's consider a case where a hook is formed on the cylindrical wall 103 instead of the antenna holding portion 109. More specifically, let's consider a main base plate 1A with a hook 1037 formed on the cylindrical wall 103. Figure 27 is a bottom view of this main base plate 1A. In the main base plate 1A shown in this figure, the hook 1037 is formed on the outer surface of the wall portion 1032 that constitutes the cylindrical wall 103.

Let's assume that, due to this change in the hook's position, the locking hole is formed in the partition wall 426 instead of the side wall 421 of the intermediate plate 4. More specifically, let's assume an intermediate plate 4A with a locking hole 4261 formed in the partition wall 426. Figure 28 is a top perspective view of this intermediate plate 4A. In the intermediate plate 4A shown in this figure, the locking hole 4261 is formed in the center of the partition wall 426. The hook 1037 is locked into this locking hole 4261.

Let's assume that the main base plate 1A and intermediate plate 4A described above are replaced with the main base plate 1 and intermediate plate 4. More specifically, let's assume a smoke detector 100A equipped with the main base plate 1A and intermediate plate 4A. Figure 29 is a longitudinal cross-sectional view of this smoke detector 100A. Note that hatching has been omitted in Figure 29 to prevent the drawing from becoming difficult to read.

In the smoke detector 100A shown in the figure, a cut-off hole 113 is formed directly above the hook 1037. This cut-off hole 113 is formed when the main body base plate 1A is molded. If an insect enters this cut-off hole 113, as shown by arrow A2 in the figure, the insect may pass between the partition wall 426 and the side wall 421 of the middle plate 4A, and enter the insect screen ring 6 through the cut-off hole 429 formed below the locking hole 4261. If the insect enters the insect screen ring 6, it may pass between the labyrinth walls 403 to 405, through the ventilation hole 402, and enter the smoke detection space. If the insect enters the smoke detection space, the light from the light-emitting part 205 may hit the insect and scatter, and be received by the light-receiving part 206. If the scattered light is received by the light-receiving part 206, a fire will be detected even though there is no actual fire. Another possibility is that the insect could enter the light-emitting unit housing space from the smoke detection space through the light-passing hole 1035. If the insect enters the light-emitting unit housing space, it could obstruct the light emission of the light-emitting unit 205, potentially preventing the detection of a fire even if one occurs. Yet another possibility is that the insect could enter the light-receiving unit housing space from the smoke detection space through the light-passing hole 1036. If the insect enters the light-receiving unit housing space, it could obstruct the light reception of the light-receiving unit 206, potentially preventing the detection of a fire even if one occurs.

In contrast, if a hook 1091 is formed on the antenna holder 109, the cutting hole 112 directly above it will be located outside the insect screen ring 6 when viewed from the side (see Figure 26). Therefore, even if an insect enters the cutting hole 112, it will be difficult for it to enter the insect screen ring 6. Consequently, the possibility of false alarms or missed fire detections due to insect intrusion is reduced.

1-7. Operation Next, the operation of the smoke detector 100 will be described. Specifically, the fire detection process, fire signal transmission process, and wireless channel setting process will be described.

First, let me explain the fire detection process.
When a fire occurs in the monitoring area of the smoke detector 100, the smoke rises towards the ceiling. Once it reaches the ceiling, it flows horizontally along the ceiling surface. When this smoke enters the smoke detector 100 through the ventilation holes 502, it passes through the insect screen ring 6 and the ventilation holes 402 of the intermediate plate 4, and enters the smoke detection space. Upon entering the smoke detection space, the light emitted from the light-emitting unit 205 strikes the smoke particles and is scattered, and the light is received by the light-receiving unit 206. When the light-receiving unit 206 receives the scattered light, it outputs a detection signal to the control circuit 214. When the control circuit 214 receives this detection signal, it emits an alarm sound from the speaker 3 and transmits a fire signal to other smoke detectors 100 and relay devices via the wireless communication circuit 215.
The above is an explanation of the fire detection process.

Next, we will explain the fire signal transmission process.
When the control circuit 214 of the smoke detector 100 receives a fire signal from another smoke detector 100, it emits an alarm sound from the speaker 3. In addition, the control circuit 214 transmits fire signals to yet another smoke detector 100 or relay device via the wireless communication circuit 215. This enables the smoke detectors 100 to be linked together.

Next, we will explain the wireless channel setting process.
When the user presses and holds the registration switch 209 of the smoke detector 100, the control circuit 214 starts the wireless channel setting mode. In this wireless channel setting mode, the control circuit 214 changes the wireless channel each time the registration switch 209 is briefly pressed. In addition, each time the wireless channel is changed, the control circuit 214 emits a guide voice from the speaker 3 notifying the wireless channel number. When the registration switch 209 is pressed and held again, the control circuit 214 remembers the number of the currently selected wireless channel and exits the wireless channel setting mode.

Subsequently, when the user presses and holds the erase switch 210, the control circuit 214 erases the stored wireless channel number.

2. Modifications The above embodiments may be modified as follows. The following modifications may be combined with each other.

2-1. Variation 1
The shape of the main base plate 1 shown in Figure 6, etc., is merely an example. The shape of the main base plate 1 may be appropriately changed depending on the shape of the battery, circuit board 2, and speaker 3 mounted on the smoke detector 100, and the type of electronic components mounted on the circuit board 2.

2-2. Modification Example 2
The cylindrical wall 103 of the main body base plate 1 has an isosceles trapezoidal shape, as shown in Figure 6. However, this shape is merely an example, and instead of an isosceles trapezoidal shape, it may have, for example, a triangular shape.

2-3. Variation 3
The ribs 104 of the main body base plate 1 have a roughly U-shape, as shown in Figure 6. However, this shape is merely an example, and instead of a roughly U-shape, it may have, for example, a semicircular shape.

As described above, the rib 104 contacts the substrate 2. However, contact between the rib 104 and the substrate 2 is not essential. A small gap may be left between the rib 104 and the substrate 2. However, this gap should be large enough to prevent insects from passing through. Specifically, for example, it may be approximately the same size as the mesh of the insect screen ring 6.

2-4. Variation 4
The ribs 105 of the main body base plate 1 have a U-shape, as shown in Figure 6. However, this shape is merely an example, and instead of a U-shape, they may have, for example, a semicircular shape.

As described above, there is a small gap between the rib 105 and the substrate 2. However, this gap is not essential. The rib 105 may be placed in contact with the substrate 2 without any gap between them.

2-5. Variation 5
The shape of the circuit board 2 shown in Figure 9, etc., is merely an example. The shape of the circuit board 2 may be changed as appropriate depending on the shape of the battery and speaker 3 mounted on the smoke detector 100, the shape of the cylindrical wall 103 of the main base plate 1, etc.

2-6. Variation 6
As described above, the notch 202 of the substrate 2 abuts against the outer surface of the cylindrical wall 103 of the main base plate 1. However, it is not essential to have the notch 202 abut against the outer surface of the cylindrical wall 103. The notch 202 may be placed close to the cylindrical wall 103 with a small gap between them, without abutting against the outer surface of the cylindrical wall 103. However, the gap in this case should be sized to prevent insects from passing through. Specifically, for example, it may be approximately the same size as the mesh of the insect screen ring 6.

The pair of notches 203 and 204 on the substrate 2 have a rectangular shape, as shown in Figure 14. However, this shape is merely an example, and instead of a rectangular shape, they may have, for example, a semicircular shape.

2-7. Variation 7
The shape of the intermediate plate 4 shown in Figure 15, etc., is merely an example. The shape of the intermediate plate 4 may be changed as appropriate depending on the shape of the battery, circuit board 2, and speaker 3 mounted on the smoke detector 100, and the type of electronic components mounted on the circuit board 2.

2-8. Variation 8
The U-shaped portion 4272 of the rib 427 of the middle plate 4 has a U-shape, as shown in Figure 22. However, this shape is merely an example, and instead of a U-shape, it may have, for example, a semicircular shape.

As described above, there is a small gap between the rib 427 and the substrate 2. However, this gap is not essential. The rib 427 may be placed in contact with the substrate 2 without any gap between them.

2-9. Modification 9
The U-shaped portion 4282 of the rib 428 of the middle plate 4 has a U-shape, as shown in Figure 22. However, this shape is merely an example, and instead of a U-shape, it may have, for example, a semicircular shape.

As described above, there is a small gap between the rib 428 and the substrate 2. However, this gap is not essential. The rib 428 may be placed in contact with the substrate 2 without any gap between them.

2-10. Variation 10
The insect screen ring 6 has a cylindrical shape, as shown in Figure 4. However, this shape is merely an example, and it may have other shapes, such as an elliptical or rectangular shape.

2-11. Variation 11
The smoke detector 100 is equipped with a rib 105 on the main base plate 1 (see Figure 6) and a pair of ribs 427 and 428 on the middle plate 4 (see Figure 17) to reduce the possibility of false alarms or missed fire detections due to insect intrusion. However, it is not essential for the smoke detector 100 to be equipped with all of these ribs. Only one or two of these ribs may be provided to the smoke detector 100.

1...Main base plate, 2...Circuit board, 3...Speaker, 4...Middle plate, 5...Main cover, 6...Insect screen ring, 7...Optical stand cover, 8...Illumination switch, 100...Smoke detector, 101...Battery housing, 102...Speaker housing, 103...Cylindrical wall, 104...Rib, 105...Rib, 106...Circuit board mounting part, 107A, 107B...Push-in part, 108, 109...Antenna holder, 110, 111...Switch holder, 201...Notch, 202...Notch, 203...Notch, 204...Notch, 205...Light-emitting part, 206...Light-receiving part, 207...Inspection switch, 208...Confirmation light, 209...Registration switch, 210...Delete switch, 211...Connector, 212...Antenna, 213...Conductor 214...control circuit, 215...wireless communication circuit, 216...through hole, 217...through hole, 401...notch, 402...ventilation hole, 403-405...labyrinth wall, 406, 407...locking hole, 408-415...antenna holding part, 416...insertion hole, 417...speaker hole, 418...switch hole, 419...indicator hole, 420...antenna hole 421...Side wall, 422-425...Locking hole, 426...Partition wall, 427, 428...Rib, 501...Switch hole, 502...Ventilation hole, 503A, 503B...Switch support part, 1031-1034...Wall section, 1035, 1036...Light passage hole, 2121...Straight section, 2122...Arc section, 2131...Straight section, 2132...Arc section

Claims (1)

The main base plate and
Equipped with a substrate,
The aforementioned main base plate is
The wall section that forms the smoke detection space,
It has ribs that protrude toward the substrate, are connected to the outer surface of the wall, and form a light-receiving unit housing space or a light-emitting unit housing space between itself and the wall,
The substrate is in contact with or close to the wall and covers the light-receiving unit housing space or the light-emitting unit housing space.
A smoke detector characterized in that the gap between the rib and the substrate is of a size that prevents insects from passing through.