A smoke alarm and a method of smoke detection

Abstract

The present application relates to early warning field, provide a kind of smoke alarm and smoke detection method, the smoke alarm at least includes: top cover, one side of top cover is conical reflecting surface;Bottom plate, one side of bottom plate is provided with first light source and first photoelectric receiver;First light source and first photoelectric receiver are all towards conical reflecting surface setting;Optical deflection grid, setting between top cover and bottom plate, it is suitable for connecting top cover and bottom plate, optical deflection grid is along the circumferential direction of bottom plate setting;Smokeless state, the light emitted by first light source is reflected after conical emission surface and shot from optical deflection grid;Smoke state, the light emitted by first light source is at least partially reflected after smoke particle and received by first photoelectric receiver.The smoke alarm, without setting complex maze structure, structure is more simple, smaller, can be applied to miniaturization application scene, in smaller space, meet the quick response of smoke detection, the applicability of product is higher.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of smoke alarm, in particular to a smoke alarm and a smoke detection method. BACKGROUND

[0002] As a very important part in the field of security, the smoke alarm is more and more valued by people. The smoke alarm mainly includes an external shell and an optical labyrinth structure inside the shell.

[0003] The existing smoke alarm often needs to set a complex labyrinth structure to avoid the light emitted by the light signal transmitter being received by the light absorber in the no-smoke state, resulting in a large volume, which is not suitable for small application scenarios. In a smaller space, it cannot meet the rapid response to smoke detection, and the applicability of the product is not high. SUMMARY

[0004] Therefore, the technical problem to be solved by the present application is that the smoke alarm in the prior art has a large volume, is not suitable for small application scenarios, cannot meet the rapid response to smoke detection in a smaller space, and has low applicability of the product, so as to provide a smoke alarm and a smoke detection method.

[0005] To solve the above technical problems, the technical scheme of the present application is as follows:

[0006] A smoke alarm at least comprises: a top cover, one side of the top cover is a conical reflecting surface; a bottom plate, one side of the bottom plate is provided with a first light source and a first photoelectric receiver; the first light source and the first photoelectric receiver are both arranged towards the conical reflecting surface; an optical deflection grid is arranged between the top cover and the bottom plate and is adapted to connect the top cover and the bottom plate, the optical deflection grid is arranged along the circumference of the bottom plate; in the no-smoke state, the light emitted by the first light source is reflected by the conical reflecting surface and then emitted from the optical deflection grid; in the smoke state, the light emitted by the first light source is at least partially reflected by the smoke particles and then received by the first photoelectric receiver.

[0007] Further, one side of the bottom plate is also provided with a second light source and a second photoelectric receiver; the second light source and the second photoelectric receiver are both arranged towards the conical reflecting surface; in the no-smoke state, the light emitted by the second light source is reflected by the conical reflecting surface and then emitted from the optical deflection grid; in the smoke state, the light emitted by the second light source is at least partially reflected by the smoke particles and then received by the second photoelectric receiver; wherein the wavelength of the light emitted by the first light source is different from the wavelength of the light emitted by the second light source, and correspondingly, the wavelength of the light receivable by the first photoelectric receiver is different from the wavelength of the light receivable by the second photoelectric receiver.

[0008] Further, the first light source and the second light source are arranged side by side, and the first photoelectric receiver and the second photoelectric receiver are arranged side by side; the orthographic projection of the vertex of the conical reflecting surface on the bottom plate does not coincide with the positions of the first light source and the second light source.

[0009] Further, the distance between the orthographic projection of the vertex of the conical reflecting surface on the bottom plate and the positions of the first light source and the second light source is less than 5 mm.

[0010] Further, at least part of the conical reflecting surface is circular arc-shaped; and the conical reflecting surface is black.

[0011] Further, the optical deflection grid comprises a plurality of deflection blades, the plurality of deflection blades are arranged in a circumferential direction along the inner wall of the optical deflection grid, and a unidirectional light channel is formed between two adjacent deflection blades; one side of each deflection blade towards the center line of the optical deflection grid comprises a light-absorbing surface and a light-reflecting surface, and the light-absorbing surface and the light-reflecting surface are arranged at a preset angle; the surface of the light-absorbing surface is coated with a light-absorbing layer, and external light is absorbed after irradiating on the light-absorbing surface; the surface of the light-reflecting surface is coated with a light-reflecting layer, and internal light is reflected to the outside after irradiating on the light-reflecting surface.

[0012] Further, the circumference of the edge of the optical deflection grid close to the side of the bottom plate is greater than the circumference of the edge close to the side of the top cover.

[0013] Further, two connecting ear plates are symmetrically arranged on the side edge of the bottom plate, and a positioning pin is arranged on one side of each connecting ear plate away from the top cover.

[0014] Further, the smoke alarm further comprises a protective shell, at least comprising: a body comprising a first cover and a second cover connected to each other; the first cover is in the form of an open box structure, the second cover is in the form of a plate structure, one end of the first cover with an opening is arranged towards the second cover, and the area between the first cover and the second cover forms a containing cavity suitable for mounting the top cover, the optical deflection grid and the bottom plate; a plurality of smoke passing holes are arranged in the circumferential direction of the first cover, at least part of each smoke passing hole is located on the side wall of the first cover, and at least part of each smoke passing hole is located on the top wall of the first cover.

[0015] The application also provides a smoke detection method, comprising the smoke alarm, and comprising the following steps: obtaining background light noise of the first photoelectric receiver and background light noise of the second photoelectric receiver in a smoke-free state; obtaining light intensity received by the first photoelectric receiver and light intensity received by the second photoelectric receiver in a smoke state; obtaining scattered light intensity received by the first photoelectric receiver and scattered light intensity received by the second photoelectric receiver; obtaining response curves of the scattered light intensity received by the first photoelectric receiver and the second photoelectric receiver with respect to time; and comparing the response curves with a standard response curve to inversely deduce different smoke types.

[0016] The technical scheme of the application has the following advantages:

[0017] The smoke alarm integrates the first light source and the first photoelectric receiver on the bottom plate, changes the light path by using the conical reflecting surface on the top cover, and guides the light emitted by the first light source out through the optical deflection grid in a smoke-free state, while preventing external light from entering and reducing the interference of ambient light. Compared with the smoke alarm in the prior art, the smoke alarm does not need to be provided with a complex labyrinth structure, has a more compact structure and a smaller size, can be applied to miniaturized application scenarios, meets the requirement of rapid response to smoke detection in a smaller space, and has higher applicability. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the specific embodiments of the application or the technical scheme in the prior art, the following will briefly introduce the drawings needed to be used in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the application, and those skilled in the art can also obtain other drawings according to these drawings without any creative effort.

[0019] Figure 1 FIG. 1 is a schematic diagram of the connection of the top cover, the optical deflection grid and the bottom plate of the smoke alarm in the embodiment of the application;

[0020] Figure 2 FIG. 2 is a schematic diagram of the internal structure of the smoke alarm in the embodiment of the application; Figure 1

[0021] Figure 3 FIG. 3 is a schematic diagram of the deflection vane in the smoke alarm in the embodiment of the application;

[0022] Figure 4 FIG. 4 is a schematic diagram of the bottom plate in the smoke alarm in the embodiment of the application;

[0023] Figure 5 FIG. 5 is a schematic diagram of the light irradiation on the conical reflecting surface in the smoke alarm in the embodiment of the application;

[0024] Figure 6 ​A schematic view of a protective shell in a smoke alarm according to an embodiment of the present application;

[0025] Figure 7 A top view of Figure 6

[0026] Figure 8 A schematic view of a second cover in a smoke alarm according to an embodiment of the present application;

[0027] Figure 9 A flow chart of a smoke detection method in a smoke alarm according to an embodiment of the present application.

[0028] 1, top cover; 2, optical deflection grid; 3, bottom plate;

[0029] 4, connecting lug; 5, positioning pin; 6, conical reflecting surface;

[0030] 7, deflection vane; 8, absorbing surface; 9, reflecting surface;

[0031] 10, first light source; 11, second light source; 12, first photoreceiver;

[0032] 13, second photoreceiver; 14, first cover; 15, second cover;

[0033] 16, smoke passage hole; 17, hollow hole; 18, first hole;

[0034] 19, second hole; 20, wing plate; 21, mounting hole;

[0035] 22, folded edge; 23, wiring hole. DETAILED DESCRIPTION

[0036] The technical solutions of the present application will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0037] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance. ​

[0038] In the description of the present application, it should be noted that unless specifically defined and limited otherwise, the terms "mounting", "connected", "connection" should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0039] In addition, the technical features involved in the different embodiments of the application described below can be combined with each other as long as there is no conflict.

[0040] Figure 1 The schematic diagram of the connection of the top cover, the optical deflection grid and the bottom plate in the smoke alarm of the embodiment of the present application; Figure 2 The schematic diagram of the connection of the top cover, the optical deflection grid and the bottom plate in the smoke alarm of the embodiment of the present application; Figure 1 The schematic diagram of the internal structure of the smoke alarm; Figure 3 The schematic diagram of the deflection vane in the smoke alarm of the embodiment of the present application; Figure 4 The schematic diagram of the bottom plate in the smoke alarm of the embodiment of the present application; Figure 5 The schematic diagram of the light irradiation on the conical reflecting surface in the smoke alarm of the embodiment of the present application; as Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 and Figure 5 The present embodiment provides a smoke alarm, which at least comprises: a top cover 1, the top cover 1 is in a circular structure as a whole, one side of the top cover 1 is a conical reflecting surface 6; a bottom plate 3, which can be a circular plate or a rectangular plate, is located below the top cover 1, and the bottom plate 3 is provided with a first light source 10 and a first photoelectric receiver 12 on the side facing the conical reflecting surface 6 of the top cover 1; the first light source 10 and the first photoelectric receiver 12 are both arranged towards the conical reflecting surface 6; an optical deflection grid 2 is arranged between the top cover 1 and the bottom plate 3, and is adapted to connect the top cover 1 and the bottom plate 3, the optical deflection grid 2 is arranged along the circumference of the bottom plate 3 and is in a ring structure as a whole; under the condition of no smoke, the light emitted by the first light source 10 is reflected by the conical reflecting surface and then emitted from the optical deflection grid 2; under the condition of smoke, the light emitted by the first light source 10 is at least partially reflected by the smoke particles and then received by the first photoelectric receiver 12.

[0041] The smoke alarm provided by the embodiment integrates the first light source 10 and the first photoelectric receiver 12 on the bottom plate 3, and changes the light path by using the conical reflecting surface 6 on the top cover 1. In the smoke-free state, the light emitted by the first light source 10 is guided out through the optical deflection grid 2, and at the same time, the external light can be prevented from entering, thereby reducing the interference of the ambient light. Compared with the smoke alarm in the prior art, the smoke alarm does not need to be provided with a complex maze structure, and the structure is more compact and smaller, so that the smoke alarm can be applied to miniaturized application scenarios, and in a smaller space, the smoke alarm can meet the requirement of rapid response to smoke detection, and the applicability of the product is higher.

[0042] In the smoke-free state, the light emitted by the second light source 11 is reflected by the conical reflecting surface 6 and then emitted from the optical deflection grid 2. In the smoke state, the light emitted by the second light source 11 is at least partially reflected by the smoke particles and then received by the second photoelectric receiver 13. The wavelength of the light emitted by the first light source 10 is different from the wavelength of the light emitted by the second light source 11, and correspondingly, the wavelength of the light that can be received by the first photoelectric receiver 12 is different from the wavelength of the light that can be received by the second photoelectric receiver 13. For example, the wavelength of the light emitted by the first light source 10 and the second light source 11 can be in the range of 400 nm-1000 nm. For example, the first photoelectric receiver 12 is provided with a filtering structure, so that the first photoelectric receiver 12 can only receive the light emitted by the first light source 10, and cannot receive the light emitted by the second light source 11. Similarly, the second photoelectric receiver 13 is provided with a filtering structure, so that the second photoelectric receiver 13 can only receive the light emitted by the second light source 11, and cannot receive the light emitted by the first light source 10. In this way, the mutual interference of the first light source 10 and the second light source 11 is prevented, and the measurement accuracy is affected.

[0043] The top point of the conical reflecting surface 6 is not coincided with the positions of the first light source 10 and the second light source 11 in the orthographic projection on the bottom plate 3. For example, the first light source 10 and the second light source 11 can be located on the left side of the projection of the top point, and the first photoelectric receiver 12 and the second photoelectric receiver 13 can be located on the right side of the projection of the top point.

[0044] Preferably, the distance between the top point of the conical reflecting surface 6 and the positions of the first light source 10 and the second light source 11 in the orthographic projection on the bottom plate 3 is less than 5 mm.

[0045] For the top cover 1, at least part of the conical reflecting surface 6 thereon is a circular arc, which can improve the reflecting effect. For example, the conical reflecting surface 6 can be coated with a black light-absorbing material, and the surface of the conical reflecting surface 6 is as smooth as possible, so as to reduce the scattering of the generated light.

[0046] The optical deflection grid 2 includes multiple deflection blades 7, which are spaced circumferentially along the inner wall of the optical deflection grid 2. For example, each deflection blade 7 is inclined relative to the radial direction of the base plate 3, and a unidirectional light channel is formed between two adjacent deflection blades 7. Each deflection blade 7 has a light-absorbing surface 8 and a reflective surface 9 on the side facing the center line of the optical deflection grid 2. The light-absorbing surface 8 and the reflective surface 9 are set at a preset angle, which is an obtuse angle. The actual angle can be adjusted as needed to improve the performance. The surface of the light-absorbing surface 8 is coated with a light-absorbing layer, so that external light is absorbed after shining on it. The surface of the reflective surface 9 is coated with a light-reflecting layer, so that internal light is reflected back to the outside after shining on it. This arrangement helps to reduce interference from ambient light.

[0047] In this configuration, the perimeter of the edge of the optical deflection grid 2 closest to the base plate 3 is greater than the perimeter of the edge closest to the top cover 1. In other words, the diameter of the entire optical deflection grid 2 gradually decreases towards the cover. The light emitted by the first light source 10 and the second light source 11 is scattered at a certain angle, essentially covering the entire conical reflective surface 6. This arrangement facilitates the reflection of light from the conical reflective surface 6 onto the reflective surface 9 in a smoke-free environment.

[0048] Two connecting lugs 4 are symmetrically arranged on the side edge of the base plate 3. The connecting lugs 4 are provided with through holes for bolts to be inserted for connection and fixing. Each connecting lug 4 has a positioning pin 5 on the side facing away from the top cover 1 for precise installation.

[0049] Figure 6 This is a schematic diagram of the protective shell in the smoke detector according to an embodiment of the present invention; Figure 7 for Figure 6 Top view; Figure 8 This is a schematic diagram of the second cover in the smoke detector according to an embodiment of the present invention, as shown below. Figure 6 , Figure 7 as well as Figure 8 As shown, the protective shell provided in this embodiment includes at least: a body, including a first cover 14 and a second cover 15 that are interlocked with each other; the first cover 14 has an open box-like structure, and the second cover 15 has a plate-like structure. The open end of the first cover 14 faces the second cover 15, and the area between the first cover 14 and the second cover 15 forms a cavity suitable for installing the top cover 1, the optical deflection grid 2, and the bottom plate 3. For example, the first cover 14 can be a cylindrical structure, and correspondingly, the second cover 15 is a circular plate. For example, the first cover 14 can also be a cuboid structure, and correspondingly, the second cover 15 is a rectangular plate.

[0050] A plurality of smoke passing holes 16 are arranged along the circumferential direction of the first cover body 14. For example, when the first cover body 14 is in a cylindrical structure, a plurality of smoke passing holes 16 can be arranged along the circumference of the first cover body 14 at certain intervals. For example, when the first cover body 14 is in a cuboid structure, smoke passing holes 16 can be arranged on the four sides of the first cover body 14. At least part of each smoke passing hole 16 is located on the side wall of the first cover body 14, and at least part of each smoke passing hole 16 is located on the top wall of the first cover body 14. For example, the smoke passing hole 16 can include a first hole 18 and a second hole 19, which are perpendicular to each other and form an L-shaped structure. The first hole 18 is located on the side wall of the first cover body 14, and the second hole 19 is located on the top wall of the first cover body 14.

[0051] The protective shell, at least part of the smoke passing hole 16 is located on the side wall of the first cover body 14, and at least part of the smoke passing hole 16 is located on the top wall of the first cover body 14. When the smoke enters the shell from the part of the smoke passing hole 16 located on the side wall of the first cover body 14, it can not only flow out from the hole body located on the top wall, but also from other smoke passing holes 16. Increase the smoke flow path, make the air circulate faster, make the response time of the components in the containing cavity to the smoke concentration change shorter, the sensitivity higher, and it is beneficial to form rapid monitoring for environmental changes.

[0052] When the first cover body 14 is in a cuboid box structure, the four sides of the first cover body 14 are provided with smoke passing holes 16, and the two smoke passing holes 16 located on the first cover body 14 and facing each other are arranged in alignment. Such an arrangement is conducive to forming convection and accelerating the flow of smoke.

[0053] The end of the second hole 19 away from the first hole 18 is arc-shaped. For example, the first hole 18 and the second hole 19 are both long strip-shaped holes, and the end of the first hole 18 away from the second hole 19 can be linear. For example, the end of the second hole 19 away from the first hole 18 can be semicircular.

[0054] The area on the top wall of the first cover body 14 not occupied by the second hole 19 can be arranged with a plurality of hollow holes 17. For example, the hollow hole 17 can be a circular hole. The hollow hole 17 can not only be used for smoke exhaust, but also can reduce the weight of the entire first cover body 14. The second cover body 15 can also be provided with hollow holes 17, for example, the hollow holes 17 on the second cover body 15 can be arranged in a ring shape for one full circle.

[0055] One of the side walls of the first cover body 14 is provided with a wire hole 23, and the wires of the electronic devices installed in the containing cavity can be led out from the wire hole 23.

[0056] The second cover body 15 is a rectangular plate, and the left and right edges of the second cover body 15 can be provided with wing plates 20, the wing plates 20 include two, and the two wing plates 20 are symmetrically arranged on the left and right sides of the second cover body 15, and two mounting holes 21 can be arranged on the plate surface of each wing plate 20, and the second cover body 15 is fixed at a target position through screws.

[0057] The front side and the rear side of the second cover body 15 can be provided with folding edges 22, the folding edges 22 are located on two different side edges adjacent to the wing plates 20 on the second cover body 15, the folding edges 22 include two, and the two folding edges 22 are arranged opposite to each other, and a convex part is arranged on a side surface of each folding edge 22 away from the center of the second cover body 15, for example, the convex part can be a hemisphere, and a concave part matched with the convex part is arranged at a corresponding position on the first cover body 14, for example, the concave part can be a hemispherical groove, and the convex part can be clamped into the concave part, so as to fix the first cover body 14 on the second cover body 15.

[0058] The second cover body 15 is provided with a through hole, and the bottom plate 3 can be mounted on the second cover body 15 by using a bolt, for example, a circuit board is mounted on the second cover body 15.

[0059] Preferably, the body is made of stainless steel.

[0060] As shown in the figure, when in use, after the airflow enters from the A direction, it can be freely diffused in the B, C and D directions, and actually, the airflow entering from any direction can be freely diffused in the other three directions.

[0061] The protective shell is designed with the smoke passing hole 16 and the hollow hole 17 on the first cover body 14, which is helpful for air convection circulation, accelerates the response time of the internal smoke, gas and temperature sensors, enables the early warning device to quickly monitor the environmental changes, and balances the airflow from all directions, so that the early warning device ensures the consistency of responses in all directions, and the design of the hollow hole 17 on the first cover body 14 and the second cover body 15 reduces the overall weight of the product under the premise of ensuring the strength.

[0062] Figure 9 The flow chart of the smoke detection method in the smoke alarm in the embodiment of the present application is as follows, Figure 9As shown, another embodiment provides a smoke detection method, including the smoke alarm described above, including the following steps: in the smoke-free state, the background light noise α1 of the first photoelectric receiver 12 and the background light noise α2 of the second photoelectric receiver 13 are obtained; in the smoke state, the light intensity received by the first photoelectric receiver 12 is β1, and the light intensity received by the second photoelectric receiver 13 is β2; the scattered light intensity received by the first photoelectric receiver 12 is obtained as γ1=β1-α1, and the scattered light intensity received by the second photoelectric receiver 13 is obtained as γ2=β2-α2; the response curves of γ1 and γ2 with time are obtained respectively; and different smoke types are obtained by comparing with the standard response curve. Wherein, the smoke detector detects the smoke by detecting the scattered light formed by the diffused smoke particles, and the stronger the scattered light intensity γ1 and γ2, the greater the smoke concentration.

[0063] Since the diameter distribution of the smoke particles is not the same as that of the dust, the smoke particles generated by different materials and different combustion types (smoldering, open fire) are also different, and the response curves of the scattered light intensity γ1 and γ2 with time generated by different wavelengths λ1 and λ2 of light on different diameter particles are also different, that is, whether the detected particles are smoke particles or dust particles can be determined by the response curves of different wavelengths of light.

[0064] Obviously, the above embodiments are only examples for clear illustration, and are not limitations on the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. All the embodiments do not need to be exhausted, and the obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A smoke detector, characterized in that, At least including: The top cover has one side that is a conical reflective surface; A base plate, one side of which is provided with a first light source and a first photoelectric receiver; Both the first light source and the first photodetector are positioned facing the conical reflective surface; An optical deflection grid is disposed between the top cover and the bottom plate, and is adapted to connect the top cover and the bottom plate. The optical deflection grid is disposed along the circumference of the bottom plate. In a smoke-free state, the light emitted by the first light source is reflected by the conical emission surface and then emitted from the optical deflection grid; In the presence of smoke, at least part of the light emitted by the first light source is reflected by the smoke particles and then received by the first photoelectric receiver. The optical deflection grid includes multiple deflection blades, which are circumferentially spaced along the inner wall of the optical deflection grid, and a unidirectional optical channel is formed between two adjacent deflection blades. Each of the deflecting blades has a light-absorbing surface and a light-reflecting surface on the side facing the center line of the optical deflection grid, and the light-absorbing surface and the light-reflecting surface are set at a preset angle. The surface of the light-absorbing surface is coated with a light-absorbing layer, and external light is absorbed after shining on the light-absorbing surface. The surface of the reflective surface is coated with a light-reflecting layer, and light from inside is reflected to the outside after shining on the reflective surface. The perimeter of the edge of the optical deflection grid near the base plate is greater than the perimeter of the edge near the top cover.

2. The smoke detector according to claim 1, characterized in that, A second light source and a second photoelectric receiver are also provided on one side of the base plate; both the second light source and the second photoelectric receiver are positioned facing the conical reflective surface. In a smoke-free state, the light emitted by the second light source is reflected by the conical emission surface and then emitted from the optical deflection grid; In the presence of smoke, the light emitted by the second light source is at least partially reflected by the smoke particles and then received by the second photoelectric receiver. The wavelength of the light emitted by the first light source is different from the wavelength of the light emitted by the second light source. Correspondingly, the wavelengths of the light that the first photodetector and the second photodetector can receive are different.

3. The smoke detector according to claim 2, characterized in that, The first light source and the second light source are arranged side by side, and the first photodetector and the second photodetector are arranged side by side; The orthographic projection of the vertex of the conical reflective surface onto the base plate does not coincide with the positions of the first light source and the second light source.

4. The smoke detector according to claim 3, characterized in that, The distance between the orthographic projection of the vertex of the conical reflective surface onto the base plate and the positions of the first and second light sources is less than 5 mm.

5. The smoke detector according to claim 1, characterized in that, At least a portion of the conical reflective surface is arc-shaped; The conical reflective surface is black.

6. The smoke detector according to any one of claims 1-5, characterized in that, Two connecting lugs are symmetrically arranged on the side edge of the base plate, and each connecting lug has a positioning pin on the side facing away from the top cover.

7. The smoke detector according to any one of claims 1-5, characterized in that, It also includes a protective shell, which includes at least: a body, including a first cover and a second cover that are interlocked and connected; The first cover has an open box structure, and the second cover has a plate structure. The open end of the first cover faces the second cover, and the area between the first cover and the second cover forms a receiving cavity suitable for installing the top cover, the optical deflection grid, and the bottom plate. A plurality of smoke passage holes are provided along the circumferential direction of the first cover body, and at least a portion of each smoke passage hole is located on the side wall of the first cover body, and at least a portion of each smoke passage hole is located on the top wall of the first cover body.

8. A smoke detection method, characterized in that, The smoke detector comprising any one of claims 2-7 includes the following steps: In a smoke-free environment, the background light noise α1 of the first photodetector and the background light noise α2 of the second photodetector are obtained. In the presence of smoke, the light intensity received by the first photodetector is β1, and the light intensity received by the second photodetector is β2. Obtain the scattered light intensity γ1=β1 -α1 received by the first photodetector, and obtain the scattered light intensity γ2=β2-α2 received by the second photodetector; Obtain the response curves of γ1 and γ2 as a function of time, respectively; By comparing with the standard response curve, different smoke types can be deduced.

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