JP5660794B2 - Photoelectric smoke detector - Google Patents

Description

The present invention relates to a photoelectric smoke sensor.

  As a conventional insect repellent net used for the photoelectric smoke detector, for example, “The insect repellent cover 4 is formed in a bottomed cylindrical shape with an insulating synthetic resin as shown in FIGS. 12 to 15. The bottom plate 4a communicates with an insertion hole 11c provided in the optical base 3, and a through hole 4d is formed through which the thermistor 6 mounted on the circuit board 2 is inserted, and the peripheral wall 4b has a plurality of holes. The insect cover 4 is attached to the optical base 3 with the lower end of the optical base 3 inserted into the cylinder, and the mesh part 4 is surrounded by the labyrinth wall 9. 4c is covered with the peripheral wall 4b, so that it is possible to prevent foreign substances such as insects from entering the smoke sensing chamber S surrounded by the labyrinth wall 9. Further, the bottom plate 4a of the insect-proof cover 4 has the structure shown in FIG. And an optical base as shown in FIG. A lid 21 that protrudes upward (on the optical base 3 side) from a portion facing the projecting portions 19 and 20 provided on the bottom plate 7 and fits into grooves 19a and 20a provided on the projecting portions 19 and 20. , 22 are integrally formed "(see Patent Document 1). That is, the insect screen described in Patent Document 1 is integrally formed with a part of the optical base cover that covers the lower opening of the optical base in order to reduce the number of parts and improve the assembly workability.

JP 2002-352347 A (paragraph 0031, FIGS. 12 to 15)

The conventional insect repellent net is formed in a substantially cylindrical shape, and a plurality of holes (for example, corresponding to the mesh portion 4c of Patent Document 1) are formed in the side surface portion thereof. For this reason, when molding a conventional insect screen, mold parts moving in the axial direction of the cylindrical shape (direction perpendicular to the penetration direction of the hole) and the penetration direction of the hole (perpendicular to the axial direction of the cylindrical shape) Mold parts that move in the right direction). Therefore, the conventional insect screen has a problem that the mold structure becomes complicated.
Further, the conventional insect net has a complicated shape when the insect net and the optical stand cover are integrally formed as disclosed in Patent Document 1, for example. For this reason, there is a problem that the mold structure is further complicated and the cost of the insect screen increases.

The present invention has been made to solve at least one of the problems as described above, is to obtain a photoelectric smoke sensor can be simplified mold structure as the first object. Also to obtain a photoelectric smoke sensor can be an optical table cover integrally formed to suppress an increase in cost and the second object.

A photoelectric smoke detector according to the present invention includes a light-emitting element that irradiates light inside, a smoke detector unit that includes a light-receiving element that receives light scattered from smoke particles and emitted from the light-emitting element, and a smoke detector unit In a photoelectric smoke detector equipped with a fire discriminating section that judges a fire based on an output signal and an insect net that becomes a smoke inflow section of the smoke detecting section, the smoke detecting section has an opening formed on one side And an optical bench provided with a light emitting element and a light receiving element, and an optical bench cover that covers at least the central portion of the opening. In addition, the plurality of hole portions are arranged in a substantially annular shape, are provided on the outer peripheral side of the cylindrical portion, and cover the remaining range of the opening.
Further, in the photoelectric smoke detector according to the present invention, each of the holes of the insect screen has a recess formed on one surface of the flat plate and an opening area smaller than the concave portion, and penetrated from the concave portion to the other of the flat plate. And a through hole, and is provided on the outer peripheral side of the cylindrical portion so that the surface on which the concave portion is formed is a surface opposite to the surface facing the optical bench.

In addition, a photoelectric smoke detector according to the present invention includes a light-emitting element that irradiates light inside, a smoke detector unit that includes a light-receiving element that receives light emitted from the light-emitting element and scattered by smoke particles , and a smoke detector In the photoelectric smoke detector, the smoke detector has an opening formed on one side, and a light emitting element and a light receiving element are provided. An optical bench, and an optical bench cover that covers the opening. The optical bench cover includes a cylindrical portion that covers the central portion of the opening, and a flat plate portion that is provided on the outer peripheral side of the cylindrical portion. , the flat plate portion is for insect screen portion in which a plurality of holes are arranged in a substantially annular peripheral portion of the cylindrical portion is formed.
Further, in the photoelectric smoke detector according to the present invention, each of the hole portions has a concave portion formed on a surface of the flat plate portion opposite to the surface facing the optical bench, and an opening area smaller than the concave portion. And a through hole penetrating the flat plate.

  In the present invention, the insect net can be formed only by the mold parts that move in the hole forming direction. For this reason, the metal mold | die structure at the time of forming an insect screen can be simplified. Each of the holes of the insect screen has a recess formed on one surface of the flat plate and a through-hole having a smaller opening area than the recess and penetrating from the recess to the other surface of the flat plate. It has become. For this reason, by providing an insect screen on the photoelectric smoke detector so that the surface with the concave portion is the surface opposite to the surface facing the optical bench, smoke with a small mass passes through the hole and smoke is detected. Non-fire sources such as steam and dust with large mass do not flow into the smoke detector. Therefore, it is possible to obtain a photoelectric smoke detector that can determine a fire without misreporting.

  In addition, by forming the through hole so as to approach the side wall of the recess located on the outer peripheral side in the arrangement shape of the hole portion, it is possible to suppress light from reaching the light receiving element from the outside.

  In addition, even when the insect screen and the optical platform cover are integrally formed (the insect screen portion is formed on the optical platform cover), the optical platform cover (insect screen) is formed only by mold parts that move in the direction of penetration of the holes. be able to. For this reason, the increase in the cost of an optical stand cover can be suppressed. Moreover, the assembly workability | operativity of a photoelectric smoke detector can be improved by integrally forming an insect screen and an optical stand cover (form an insect screen part on an optical stand cover).

  In addition, by assembling the optical platform cover with the insect screen portion integrally with the housing, the assembly workability of the photoelectric smoke detector can be further improved.

It is a bottom view which shows the smoke detection part of the fire alarm which concerns on Embodiment 1 of this invention. It is a side view of the smoke detector shown in FIG. It is a bottom view which shows the smoke detection part of the state which removed the optical stand cover in the fire alarm which concerns on Embodiment 1 of this invention. It is BB sectional drawing (front sectional drawing) of FIG. It is AA sectional drawing of FIG. It is a bottom view of the fire alarm which concerns on Embodiment 1 of this invention. It is CC sectional drawing (front sectional drawing) of FIG. It is a bottom view of the fire alarm which concerns on Embodiment 2 of this invention. It is DD sectional drawing of FIG. It is EE sectional drawing of FIG. It is a disassembled perspective view of the fire alarm which concerns on Embodiment 2 of this invention. It is a disassembled perspective view of the fire alarm which concerns on Embodiment 2 of this invention.

  In the following Embodiment 1 and Embodiment 2, the case where the present invention is applied to a fire alarm device in which an alarm device such as a push button switch or a buzzer is provided in the configuration of the photoelectric smoke detector will be described.

Embodiment 1 FIG.
FIG. 1 is a bottom view showing the smoke detector of the fire alarm according to Embodiment 1 of the present invention. FIG. 2 is a side view of the smoke detector. FIG. 3 is a bottom view showing a state in which the optical bench cover of the smoke detector is removed. 4 is a BB cross-sectional view of FIG. 1, and is a vertical cross-sectional view when the fire alarm device according to Embodiment 1 of the present invention is viewed from the front. 5 is a cross-sectional view taken along the line AA in FIG. Hereinafter, the smoke detector 1 of the fire alarm device 100 according to the first embodiment will be described with reference to FIGS. 1 to 5. In the following description (including the second embodiment described later), the description will be made in accordance with the vertical and horizontal directions of FIG.

  The smoke detector 1 of the fire alarm 100 includes an optical bench 21, a light emitting element 22, a light receiving element 23, a light shielding member 24, and an optical bench cover 10 that covers a lower opening of the optical bench 21. The optical bench 21 has a substantially cylindrical shape with an opening at the bottom, and is provided with a light emitting element holder 26 for accommodating the light emitting element 22 and a light receiving element holder 27 for accommodating the light receiving element 23. The outer end portions of the light emitting element holder 26 and the light receiving element holder 27 are provided so as to protrude from the outer peripheral portion of the optical bench 21. By covering the lower opening of the optical bench 21 with an optical bench cover 10 described later, the inside of the optical bench 21 becomes a dark box.

  The light emitting element holder 26 is provided with a pair of holding members 26a made of hooks, for example. The light emitting element 22 is accommodated in the light emitting element holder 26 while being held between the holding members 26 a. At this time, the lead portion of the light emitting element 22 is bent at a substantially right angle, is inserted through a through hole 26 b formed in the light emitting element holder 26, and protrudes from the upper surface portion of the optical bench 21.

  The light receiving element 23 is provided in the shield case 28 and is housed in the light receiving element holder 27 together with the shield case 28. The shield case 28 has a substantially rectangular tube shape with an opening in a range facing the light receiving part of the upper part and the light receiving element 23. The shield case 28 is provided with a holding member 28 a made of, for example, a pressing piece. The light receiving element 23 is sandwiched between the side surface portion of the shield case 28 and the holding member 28 a and is provided in the shield case 28. A convex portion 28b is formed on the upper portion of the shield case 28. By inserting the convex portion 28b into an opening formed in the circuit board 2 and soldering, the shield case 28 and the light receiving element 23 are fixed. ing.

  In a state in which the light emitting element 22 and the light receiving element 23 are housed in the optical bench 21, the light emitting element 22 is provided so that its optical axis 22a faces the substantially central portion of the optical bench 21, and the light receiving element 23 has its light. The shaft 23 a is provided so as to face the substantially central portion of the optical bench 21. Further, the optical axis 22a of the light emitting element 22 and the optical axis 23a of the light receiving element 23 are substantially parallel in a side view, and form a predetermined angle at which the light receiving element does not directly receive the irradiation light from the light emitting element 22 in a plan view. Is provided. Then, smoke is detected by a smoke detection unit which is a superposition part of the irradiation range of the light emitting element 22 and the light receiving range of the light receiving element 23. More specifically, the light receiving element 23 receives light scattered by the smoke irradiated from the light emitting element 22 by the smoke entering the smoke detecting unit.

  Further, a light shielding member 24 is erected on the optical bench 21 on the side where the angle formed by the optical axis 22a of the light emitting element 22 and the optical axis 23a of the light receiving element 23 is an obtuse angle. The cross-sectional shape of the light shielding member 24 in plan view is, for example, substantially V-shaped. Thus, the light shielding member 24 is formed with an edge portion 24a and an edge portion 24b. The edge portion 24a prevents the light receiving element 23 from directly receiving the light emitted from the light emitting element 22. The edge portion 24b prevents the light receiving element 23 from receiving the light irregularly reflected by the edge portion 24a.

  An optical trap 29 for attenuating light emitted from the light emitting element 22 is provided in the vicinity of the peripheral wall of the optical bench 21 that faces the light emitting element 22. The optical trap 29 includes a plurality of wall bodies 29a. The light emitted from the light emitting element 22 is attenuated by being repeatedly reflected between the wall bodies 29a. Further, the plurality of wall bodies 29a extend substantially linearly with the plane portion facing the light emitting element 22 so that the irradiation light repeats a predetermined number of reflections for each of the narrow paths formed on the peripheral walls between them. Furthermore, the edge shape of the inner side edge part of the some wall body 29a is made into the acute angle. As a result, the light emitted from the light emitting element 22 can be reliably attenuated by the light trap 29, thereby preventing a large amount of stray light from entering the smoke detector 1. The number and shape of the plurality of wall bodies 29a of the optical trap 29 are appropriately determined according to the irradiation pattern (not shown) of the light emitting element 22.

  The optical table cover 10 is composed of a cylindrical portion 11, a flat plate portion 12, and the like. The cylinder part 11 has a substantially cylindrical shape, for example, and has a shape in which the lower part is closed. A substantially disk-shaped flat plate portion 12 is provided on the outer peripheral side of the cylindrical portion 11. The flat plate portion 12 is provided on the outer peripheral side of the cylindrical portion 11 so that the upper end portion 11 a of the cylindrical portion 11 protrudes from the upper surface of the flat plate portion 12. By projecting the upper end portion of the cylinder portion 11 from the upper surface of the flat plate portion 12, smoke flowing in the horizontal direction hits the projecting peripheral wall, so that it can flow into the smoke detector portion 1 from the insect screen 30 described later. A convex portion 12 b is formed on the outer peripheral portion of the flat plate portion 12 at a position corresponding to the light emitting element holder 26. The optical bench cover 10 is also provided with a plurality of ribs 13 that connect the tube portion 11 and the flat plate portion 12 and guide smoke from the horizontal direction. In addition, the shape of the cylinder part 11 is not restricted to a substantially cylindrical shape. For example, the cylinder portion 11 may be formed in a substantially rectangular tube shape.

  The flat plate portion 12 is formed with an insect screen portion 30 in which a plurality of hole portions 31 are arranged in a substantially annular shape at the peripheral edge portion of the cylindrical portion 11. That is, the optical bench cover 10 (more specifically, the flat plate portion 12) according to the first embodiment is formed by integrally forming an insect screen. In other words, the insect screen 30 is a smoke inflow portion to the smoke detector 1. In addition, the arrangement | positioning shape of the hole part 31 should just be substantially cyclic | annular form, and what is necessary is just to change the shape suitably according to shapes, such as the optical stand 21 and the cylinder part 11. For example, when the cylinder part 11 is a substantially square cylinder shape, you may form the hole part 31 in the substantially cyclic | annular form (in other words, substantially frame shape) which becomes a planar view square shape. Here, the hole portion 31 is not formed in the insect screen 30 in the range facing the light emitting element holder 26 and the light receiving element holder 27, but in the first embodiment, it is referred to as a substantially annular shape.

  The hole 31 is formed by a recess 31a and a through hole 31b. The recess 31a has, for example, a substantially rectangular shape in plan view, and is formed on the lower surface of the flat plate portion 12. In addition, the planar view shape of the recessed part 31a can be made into arbitrary shapes not only in a substantially rectangular shape. For example, the planar view shape of the recess 31a may be formed in a substantially circular shape. The concave portion 31a communicates with the upper surface side of the flat plate portion 12 through, for example, a substantially rectangular through hole 31b in plan view. In addition, the planar view shape of the through hole 31b is not limited to a substantially rectangular shape, and may be an arbitrary shape. For example, the plan view shape of the through hole 31b may be formed in a substantially circular shape.

  More specifically, the through hole 31b is formed so as to be in contact with the side wall of the recess 31a located on the outer peripheral side (the outer peripheral side of the flat plate portion 12) in the arrangement shape of the hole portion 31. Thus, the light that has passed through the hole 31 flows into the optical bench 21 while moving toward the outer periphery of the optical bench 21. The light is reflected by the peripheral wall of the optical bench 21 and attenuated. For this reason, by forming the through hole 31b so as to be in contact with the side wall of the recess 31a located on the outer peripheral side (the outer peripheral side of the flat plate part 12) in the arrangement shape of the hole part 31, the external light entering from the hole part 31 is directly Reaching the light receiving element can be suppressed. The through hole 31b is not necessarily in contact with the side wall of the recess 31a located on the outer peripheral side (the outer peripheral side of the flat plate part 12) in the arrangement shape of the hole part 31. If the through hole 31b is formed near the side wall of the concave portion 31a located on the outer peripheral side (the outer peripheral side of the flat plate portion 12) in the arrangement shape of the hole portion 31, the external light flowing in from the hole portion 31 directly goes to the light receiving element. It can suppress reaching.

  Further, on the upper surface of the flat plate portion 12, an engaging portion 12 a having a shape corresponding to the lower outer peripheral shape of the optical bench 21 is projected. By engaging the engaging portion 12a with the lower outer periphery of the optical bench 21, the optical bench cover 10 is attached to the optical bench 21 and the inside of the optical bench 21 is made a dark box.

  In the first embodiment, the insect net is integrally formed with the optical bench cover 10 (more specifically, the flat plate portion 12) as the insect net portion 30, but the optical bench cover 10 and the insect net (insect net 30) are separately provided. Of course, it may be formed of a body. That is, a separate insect net may be attached in the vicinity of the smoke inflow portion to the smoke detector 1. In the first embodiment, in order to improve the assembly workability of the fire alarm 100, an insect screen is integrally formed with the optical bench cover 10 (more specifically, the flat plate portion 12) as the insect screen unit 30.

  The smoke detector 1 is mounted on the lower surface of the circuit board 2 (see FIG. 7 described later). A plurality of electrical components (not shown) are mounted on the circuit board 2, and these electrical components constitute the fire determination unit 3 and the like. In a state where the smoke detector 1 is mounted on the circuit board 2, the light emitting element 22 and the light receiving element 23 and the fire determination unit 3 are electrically connected. And the fire discrimination | determination part 3 discriminate | determines whether the fire broke out based on the light reception amount which the light receiving element 23 detects. The amount of received light detected by the light receiving element 23 is output to the fire discriminating unit 3 by voltage or the like, for example.

FIG. 6 is a bottom view of the fire alarm device according to the first embodiment of the present invention. Moreover, FIG. 7 is CC sectional drawing (front sectional drawing) of FIG.
As shown in FIGS. 6 and 7, the smoke detector 1 and the circuit board 2 are accommodated in a housing 40 and constitute a fire alarm 100. The housing 40 includes a protective cover 41 and a main body 45.

  The protective cover 41 has a bottomed cylindrical shape that expands toward the upper side, and a substantially circular opening 41a is formed in a substantially central portion of the lower portion. The opening 41a has a shape corresponding to the outer peripheral shape of the smoke detector 1 (more specifically, the outer peripheral shape of the flat plate portion 12 of the optical bench cover 10). A flat plate portion 42 is provided below the opening 41 a via a plurality of ribs 43. Thus, a smoke inlet 41b is formed on the side surface of the lower portion of the protective cover 41. The opening 41c formed in the protective cover 41 is for projecting a fire alarm indicator light from the protective cover 41.

  The main body 45 has an outer peripheral shape corresponding to the upper inner peripheral shape of the protective cover 41. On the lower surface of the main body 45, a circuit board 2 on which the smoke detector 1 and the like are mounted is provided. The housing 40 is assembled by engaging the main body 45 with the upper portion of the protective cover 41. At this time, the optical stage cover 10 of the smoke detector 1 is placed in the opening 41 a of the protective cover 41.

  The fire alarm 100 is installed in a monitoring space such as a room in a house, for example. In a state where the fire alarm 100 is attached to the ceiling surface of the monitoring space, the fire alarm 100 is installed with the smoke inlet 41b on the lower side, as shown in FIG. The fire alarm 100 uses, for example, a lithium battery (not shown) as a drive source. Of course, power may be supplied to the fire alarm 100 from an external power source (not shown).

(Description of operation)
Next, the operation of the fire alarm device 100 according to the first embodiment will be described. In FIGS. 4 and 7, the flow of smoke is indicated by broken-line arrows.

The smoke generated by the fire flows along the ceiling surface or the like of the monitoring space and flows into the vicinity of the smoke detection unit 1 from the smoke inlet 41b.
Smoke tends to change its flow state because of its small particle mass and low inertia. For this reason, the smoke that has reached the vicinity of the smoke detector 1 passes through the hole 31 (the recess 31a and the through hole 31b) of the insect screen 30 and flows into the smoke detector 1. In the first embodiment, the smoke 31 is more likely to flow into the smoke detecting section 1 because the recess 31 having a larger opening area than the through hole 31b opens downward.

  When smoke flows into the smoke detector 1, the light emitted from the light emitting element 22 is scattered by the smoke. This scattered light is received by the light receiving element 23. That is, the amount of light received by the light receiving element 23 changes. The light receiving element 23 outputs a detection value (voltage or the like) corresponding to the amount of received light to the fire determination unit 3. Based on this detection value, the fire determination unit 3 determines whether or not a fire has occurred. When it is determined that a fire has occurred, the fire discriminating unit 3 warns the surroundings that a fire has occurred by an indicator device such as an LED or an alarm device (not shown) such as a buzzer.

  On the other hand, non-fire sources such as steam and dust have a large particle mass and a large inertia, so that it is difficult to change the flow state. For this reason, non-fire reporting sources such as steam and dust that have reached the vicinity of the smoke detector section 1 hardly pass through the hole 31 of the insect screen 30 (almost without flowing into the smoke detector section 1), It flows out of the fire alarm 100 along the cylindrical part 11 of the optical base cover 10 and the peripheral walls of the plurality of ribs 13. For this reason, in the smoke detector section 1, the light emitted from the light emitting element 22 is not scattered (or little) by non-fire reporting sources such as steam and dust. Therefore, even if steam flows into the smoke detector 1, the fire discriminator 3 does not erroneously determine that it is a fire. In the first embodiment, the inside and the outside of the smoke detector section 1 are communicated with each other through the through hole 31b that is a pore. For this reason, non-fire reporting sources such as steam and dust that have reached the vicinity of the smoke detector 1 are less likely to flow into the smoke detector 1.

  In the fire alarm 100 configured as described above, smoke with a small mass flows into the smoke detector section 1 through the holes 31 (the concave portions 31a and the through holes 31b) of the insect screen 30 and steam with a large mass. Non-fire sources such as dust and dust do not flow into the smoke detector section 1. Therefore, it is possible to obtain the fire alarm 100 that can determine a fire without misreporting. Further, since the through hole 31b is formed so as to be in contact with the side wall of the concave portion 31a located on the substantially annular outer peripheral side (the outer peripheral side of the flat plate portion 12), the light flowing from the hole portion 31 reaches the light receiving element. This can be suppressed, and the false alarm of the fire alarm device 100 can be further prevented.

  Further, when the optical platform cover 10 and the insect net (insect net 30) are formed separately, the insect net has a plate in which a plurality of holes 31 (recesses 31a and through holes 31b) are arranged in a substantially annular shape. It becomes. At this time, the formation direction of the hole 31 (the depression direction of the recess 31a and the penetration direction of the through hole 31b) is formed in the thickness direction of the flat plate. For this reason, it is possible to form an insect repellent net only with mold parts that move in the direction in which the hole 31 is formed, and it is possible to simplify the mold structure when forming the insect repellent net.

  Further, even when the optical bench cover 10 and the insect net (insect net portion 30) are integrally formed, the optical bench cover 10 can be formed only by mold parts that move in the direction in which the hole 31 is formed. For this reason, even when the optical bench cover 10 and the insect net (insect net portion 30) are integrally formed, the mold structure for forming the optical bench cover 10 can be simplified. Therefore, an increase in the cost of the optical bench cover 10 can be suppressed. Moreover, the assembly workability | operativity of the fire alarm 100 can also be improved by integrally forming the optical stand cover 10 and an insect net (insect net part 30).

  Even if the fire alarm 100 is installed on the side wall surface substantially orthogonal to the ceiling surface, the smoke flows as shown in FIGS. 4 and 7, so that the same effect as when the ceiling surface is mounted can be obtained.

Embodiment 2. FIG.
In the first embodiment, the optical bench cover 10 and the insect net (insect net 30) are integrally formed. However, the optical bench cover 10 may be further integrally formed with the protective cover 41. In the second embodiment, items that are not particularly described are the same as those in the first embodiment, and the same functions and configurations are described using the same reference numerals.

  FIG. 8 is a bottom view of the fire alarm device according to the second embodiment of the present invention. 9 is a cross-sectional view taken along the line DD of FIG. 10 is a cross-sectional view taken along line EE in FIG. 11 and 12 are exploded perspective views of the fire alarm. FIG. 11 shows an exploded perspective view of the fire alarm device 100 as viewed from below, and FIG. 12 shows an exploded perspective view of the fire alarm device 100 as viewed from above. Hereinafter, the smoke detector unit 1 of the fire alarm device 100 according to the second embodiment will be described with reference to FIGS.

In the fire alarm device 100 according to the second embodiment, the protective cover 41 and the optical bench cover 10 are integrally formed. More specifically, the optical base cover 10 of the fire alarm device 100 according to the second embodiment is configured so that the opening 41a of the protective cover 41 shown in the first embodiment is the optical base cover 10 shown in the first embodiment. It has a closed shape. Further, the optical base cover 10 of the fire alarm 100 according to the second embodiment is configured such that the flat plate portion 42 and the rib 43 of the protective cover 41 shown in the first embodiment are not provided. For this reason, the protective cover 41 of the fire alarm 100 according to the second embodiment is a mold part that moves in the forming direction of the hole 31 (the recess direction of the recess 31a and the penetration direction of the through hole 31b) of the insect screen 30. The protective cover 41 can be formed only by this.
In addition, the other structure of the fire alarm device 100 which concerns on this Embodiment 2 is the same as that of the fire alarm device 100 which concerns on Embodiment 1. FIG.

  Also in the fire alarm 100 configured as in the present embodiment, smoke having a small mass passes through the hole portion 31 (the recessed portion 31a and the through hole 31b) of the insect screen 30 as in the first embodiment. No fire source such as steam or dust having a large mass flows into the smoke detector 1. Therefore, it is possible to obtain the fire alarm 100 that can determine a fire without misreporting. Further, since the through hole 31b is formed so as to be in contact with the side wall of the concave portion 31a located on the substantially annular outer peripheral side (the outer peripheral side of the flat plate portion 12), the light flowing from the hole portion 31 reaches the light receiving element. This can be suppressed, and the false alarm of the fire alarm device 100 can be further prevented.

  In addition, since the protective cover 41 according to the second embodiment can be formed only by mold parts that move in the direction in which the holes 31 of the insect screen 30 are formed, the protective cover 41 and the optical platform cover 10 are integrated. Even when formed, the increase in the cost of the protective cover 41 can be suppressed. Moreover, the assembly workability | operativity of the fire alarm device 100 can also be improved further by forming the protective cover 41 and the optical stand cover 10 integrally.

  As described above, in the first and second embodiments, the present invention is applied to the scattered light type fire alarm device 100, but it is of course possible to implement the present invention in a fire detector.

  DESCRIPTION OF SYMBOLS 1 Smoke detection part, 2 Circuit board, 3 Fire discrimination part, 10 Optical stand cover, 11 Tube part, 11a Upper end part, 12 Flat plate part, 12a Engagement part, 12b Convex part, 13 Rib, 21 Optical stand, 22 Light emitting element , 22a optical axis, 23 light receiving element, 23a optical axis, 24 light shielding member, 24a edge part, 24b edge part, 26 light emitting element holder, 26a holding member, 26b through hole, 27 light receiving element holder, 28 shield case, 28a holding member 28b Convex part 29 Light trap 29a Wall body 30 Insect screen part 31 Hole part 31a Concave part 31b Through hole 40 Case 41 Protection cover 41a Opening part 41b Smoke inlet 41c Opening part 42 Flat plate part, 43 Rib, 45 Main body, 100 Fire alarm.

Claims (4)

A light-emitting element that irradiates light inside, and a smoke detector unit that includes a light-receiving element that receives light emitted from the light-emitting element and scattered by smoke particles;
A fire discriminating unit for judging a fire based on an output signal of the smoke detecting unit;
An insect net that serves as a smoke inlet of the smoke detector;
In the photoelectric smoke detector with
The smoke detector
An optical base having an opening formed on one side and provided with the light emitting element and the light receiving element;
A cylindrical portion that covers the central portion of the opening is formed, and an optical table cover that covers at least the central portion of the opening,
Have
The insect screen is
A plurality of holes are arranged in a substantially annular shape on the flat plate,
A photoelectric smoke detector provided on the outer peripheral side of the cylindrical portion and covering the remaining range of the opening. Each of the holes of the insect net is
A recess formed on one surface of the flat plate;
An opening area smaller than the recess, and a through-hole penetrating from the recess to the other of the flat plate,
2. The photoelectric smoke detector according to claim 1 , wherein the concave portion is provided on an outer peripheral side of the cylindrical portion so that a surface opposite to a surface facing the optical bench is provided. . A light-emitting element that irradiates light inside, and a smoke detector unit that includes a light-receiving element that receives light emitted from the light-emitting element and scattered by smoke particles;
A fire discriminating unit for judging a fire based on an output signal of the smoke detecting unit;
In the photoelectric smoke detector with
The smoke detector
An optical base having an opening formed on one side and provided with the light emitting element and the light receiving element;
An optical table cover covering the opening;
Have
The optical bench cover is
A cylindrical portion covering the central portion of the opening, and a flat plate portion provided on the outer peripheral side of the cylindrical portion,
The photoelectric smoke detector according to claim 1, wherein the flat plate portion is formed with an insect net portion having a plurality of holes arranged in an annular shape at a peripheral portion of the cylindrical portion. Each of the holes is
A recess formed on the surface of the flat plate portion opposite to the surface facing the optical bench;
4. The photoelectric smoke detector according to claim 3 , further comprising a through-hole having an opening area smaller than that of the concave portion and penetrating the flat plate from the concave portion.

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