Optical smoke detector and method thereof

Abstract

A smoke detector and method thereof are provided. The smoke detector comprises a detection chamber (210), at least one light source (220), at least one light receiver (230), and a controller (240) connected to the light source (220) and the light receiver (230). The controller (240) is configured to send a contamination fault (FAULT) message if it is determined that a light signal (S) detected by the light receiver (230) is greater than a predetermined threshold (Th) and the detected light signal (S) exhibits a small fluctuation during a predetermined period (P) after power-up. The smoke detector can timely report a contamination fault message after power-up, and can accurately report a fire alarm if a fire occurs at power-up.

Description

Technical Field

[0001] This invention relates generally to the field of fire alarming, and more particularly to an optical smoke detector in a fire protection system and its alarm method. Background Technology

[0002] Smoke detectors are widely used detection devices in the fire protection field. Smoke detectors are divided into two types: those that are photosensitive and those that combine photosensitive and temperature-sensitive methods. Photosensitive smoke detectors, also known as optical smoke detectors, distinguish between moisture and smoke that may cause a fire based on the different degrees to which smoke particles scatter light. These optical smoke detectors generally have a detection chamber, and a light source and a light receiver placed within the chamber. The light source shines light into the detection chamber. This light is scattered by the smoke particles present in the chamber. The light receiver senses the light scattered by the smoke particles and determines the presence of a fire based on the characteristics of the scattered light, and then reports the fire alarm accordingly.

[0003] Since optical smoke detectors rely on the detection of scattered light, the cleanliness of the detection chamber, as well as the cleanliness of the light source and receiver surfaces, directly affects the fire alarm sensitivity of the smoke detector. In contaminated conditions, if the concentration of dust particles in the detection chamber reaches a certain level, the smoke detector may mistakenly report a fire alarm due to light scattering caused by dust. In other words, for optical smoke detectors, both dust and smoke can produce sufficiently strong light scattering signals, causing the detector to trigger a fire alarm. Therefore, how optical smoke detectors distinguish between smoke and dust (or contamination) is a problem that needs to be solved.

[0004] Existing optical smoke detectors periodically monitor and assess the level of dust (or contamination) during normal operation, and utilize dust compensation algorithms to eliminate the adverse effects caused by dust or contamination, thereby eliminating false fire alarms during normal operation. However, at the initial power-on of the smoke detector, due to the lack of dust monitoring data, the dust compensation algorithm fails to achieve the expected results.

[0005] For example, if a smoke detector is installed on-site, and the fire protection system needs to be shut down for a period of time due to reasons such as renovation work, the smoke detector may experience severe air pollution during this shutdown period. This allows dust to enter the detector's detection chamber. When the fire protection system is powered on again, the optical smoke detector may mistakenly detect the dust as a fire alarm due to the severe contamination.

[0006] Given the above, a new trend is to test smoke detectors' ability to accurately report dust or contamination fault messages upon power-up, during the national mandatory standard testing process. A proposed testing method generally includes the following steps: First, place the optical smoke detector in a dust test chamber for a period of time (approximately two hours) until the dust concentration reaches a sufficient level. Then, power on the optical smoke detector and check its operational status. If the smoke detector issues a contamination fault message, the test is considered successful. If the smoke detector does not report a contamination fault message, its fire alarm sensitivity is checked. If the fire alarm sensitivity is acceptable, place it back in the dust test chamber. If the fire alarm sensitivity is unacceptable, the test fails. This process is repeated approximately four times. This testing method can determine whether the smoke detector can accurately report a contamination fault upon power-up and whether its fire alarm sensitivity meets the standard requirements.

[0007] To avoid false fire alarms at the initial power-on stage, a common solution is to prioritize reporting pollution faults. An example procedure is as follows: Figure 1 As shown in the image. Figure 1 As shown, the method flow begins with step S110. In step S110, the smoke detector is powered on, and initialization is completed in step S120. In step S130, the smoke detector detects the light signal S detected by its optical receiver within a predetermined time period P after power-on. Then, in step S140, the light signal S is judged. If the light signal S is determined to be greater than a predetermined threshold Th in step S140, the process proceeds to step S150 to report a pollution fault FAULT message; otherwise, the process proceeds to step S190, i.e., normal operation begins. Here, the threshold Th is the fire alarm threshold. Figure 1 The method shown can successfully report pollution fault messages at the initial power-on and also successfully pass the dust test recommended above. However, if a fire actually occurs at the initial power-on, then... Figure 1 The method shown can lead to missed fire alarms, which can result in personal injury or property damage. Summary of the Invention

[0008] One objective of this invention is to provide a smoke detector and method for a fire protection system. Using this smoke detector and method, a pollution fault message can be successfully reported when the smoke detector is powered on, and if a fire occurs when the smoke detector is powered on, the smoke detector can also report a fire alarm in a timely manner.

[0009] According to one aspect of the present invention, a smoke detector is provided, comprising: a detection cavity adapted to receive particulate gas from outside the smoke detector; at least one light source adapted to direct light into the detection cavity; at least one light receiver for detecting light signals scattered by particles within the detection cavity; and a controller connected to the light source and the light receiver, configured to, within a predetermined period after power-on, issue a pollution fault message if it is determined that the light signal detected by the light receiver is greater than a predetermined threshold and the detected light signal exhibits slight fluctuations during the predetermined period. Preferably, the detected light signal exhibits slight fluctuations within a first predetermined fluctuation range during the predetermined period. Preferably, the controller is further configured to, within the predetermined period after power-on, issue a fire alarm message if it is determined that the light signal detected by the light receiver is greater than the predetermined threshold and the detected light signal exceeds the first predetermined fluctuation range during the predetermined period.

[0010] The aforementioned smoke detector not only determines a fire alarm based on whether the detected light signal exceeds a threshold, but also further distinguishes between pollution faults and fire alarms based on whether the light signal S fluctuates significantly within a predetermined time period P after power-on. In this way, the smoke detector can promptly report pollution fault messages upon power-on, and simultaneously report a fire alarm promptly if a fire occurs during power-on, without being missed due to pollution interference. Therefore, the aforementioned smoke detector can also successfully pass the previously mentioned dust test.

[0011] Preferably, the controller is further configured to: within the predetermined time period after power-on, if the controller determines that the optical signal detected by the optical receiver is greater than the predetermined threshold, and the detected optical signal exceeds a second predetermined fluctuation range during the predetermined time period, then issue a fire alarm message, wherein the second predetermined fluctuation range is greater than the first predetermined fluctuation range.

[0012] This smoke detector uses a dual fluctuation range criterion to distinguish between pollution faults and fire alarms. Using this criterion, a pollution fault is only identified when the fluctuation in the light signal is minimal (within the first fluctuation range), and a fire alarm is only identified when the fluctuation is significant (greater than the second fluctuation range). This dual fluctuation range criterion provides a more accurate distinction between pollution faults and fire alarms, further reducing false alarms and missed fire alarms.

[0013] Preferably, the smoke detector further includes a temperature sensor that detects the temperature inside or near the detection cavity. Furthermore, the controller is configured to: within a predetermined time period after power-on, if the controller determines that the light signal detected by the light receiver is greater than a predetermined threshold, the detected light signal is less than a first predetermined fluctuation range during the predetermined time period, and the temperature increase detected by the temperature sensor exceeds a predetermined temperature difference threshold, then issue a fire alarm message.

[0014] Preferably, the smoke detector further includes a temperature sensor that detects the temperature inside or near the detection cavity. Furthermore, the controller is configured to: within a predetermined time period after power-on, if the controller determines that: the light signal detected by the light receiver is greater than a predetermined threshold, the detected light signal is greater than a first predetermined fluctuation range but less than a second predetermined fluctuation range during the predetermined time period, and the temperature increase detected by the temperature sensor exceeds a predetermined temperature difference threshold, then issue a fire alarm message.

[0015] The aforementioned smoke detection further incorporates a temperature gradient criterion. For fires with minimal initial light signal fluctuations (such as the burning of plastics or other organic materials), the temperature gradient criterion can help identify the fire at an earlier stage, further reducing missed fire alarms. Furthermore, since the temperature sensor can be an existing component of the smoke detector, this approach does not increase the hardware cost or complexity of the smoke detector.

[0016] Preferably, the threshold is a fire alarm threshold, or the predetermined temperature difference is a fire alarm temperature threshold. More preferably, the first predetermined fluctuation range is less than or equal to ±8%, preferably less than or equal to ±5%, and particularly preferably equal to 2%; the second predetermined fluctuation range is greater than or equal to ±8%, preferably greater than or equal to ±10%; and the predetermined temperature difference threshold is greater than or equal to 8°C, preferably greater than or equal to 10°C. More preferably, the predetermined time period is generally between 2s and 180s, preferably between 30s and 180s, more preferably between 50s and 110s, and particularly preferably 60s or 100s.

[0017] According to another aspect of the present invention, a method for reporting pollution faults using an optical smoke detector is provided. The method includes: detecting a light signal within a predetermined time period after the smoke detector is powered on; and, if the detected light signal is greater than a predetermined threshold and exhibits slight fluctuations during the predetermined time period, issuing a pollution fault message. Preferably, the detected light signal exhibits slight fluctuations within a first predetermined fluctuation range during the predetermined time period.

[0018] Preferably, the method further includes: if, during the predetermined time period after power-on, the detected optical signal is greater than the predetermined threshold, and the detected optical signal exceeds a second predetermined fluctuation range during the predetermined time period, then a fire alarm message is issued, wherein the second predetermined fluctuation range is greater than the first predetermined fluctuation range.

[0019] More preferably, the method further includes: detecting the temperature inside or near the detection cavity of the smoke detector, and, within the predetermined time period after power-on, if the detected light signal is greater than the predetermined threshold, the detected light signal is greater than the first predetermined fluctuation range but less than the second predetermined fluctuation range during the predetermined time period, and the detected temperature increase exceeds a predetermined temperature difference threshold, then a fire alarm message is issued.

[0020] Preferably, the threshold is a fire alarm threshold. Preferably, the predetermined temperature difference is a fire alarm temperature threshold. Preferably, the first predetermined fluctuation range is less than or equal to ±8%, preferably less than or equal to ±5%, and more preferably equal to 2%. Preferably, the second predetermined fluctuation range is greater than or equal to ±8%, preferably greater than or equal to ±10%. Preferably, the predetermined temperature difference threshold is greater than or equal to 8°C, preferably greater than or equal to 10°C.

[0021] According to another aspect of the present invention, a smoke detector is provided, comprising: a detection cavity adapted to receive particulate gas from outside the smoke detector; at least one light source adapted to direct light into the detection cavity; at least one light receiver for detecting a light signal formed by scattering of particles within the detection cavity; and a controller connected to the light source and the light receiver, configured to: enter normal operation if, within a predetermined time period after power-on, the light signal detected by the light receiver is determined to be less than a predetermined threshold; and, within the predetermined time period after power-on, if the light signal detected by the light receiver is determined to be greater than the predetermined threshold, and the detected light signal exhibits slight fluctuations during the predetermined time period, issue a pollution fault message. Preferably, the detected light signal exhibits slight fluctuations within a first predetermined fluctuation range during the predetermined time period.

[0022] According to another aspect of the present invention, a method for reporting pollution faults by an optical smoke detector is provided. The method includes: detecting a light signal within a predetermined time period after the smoke detector is powered on; if, within the predetermined time period after power-on, the light signal detected by the light receiver is determined to be less than a predetermined threshold, then entering normal operation; if, within the predetermined time period after power-on, the detected light signal is greater than the predetermined threshold, and the detected light signal exhibits slight fluctuations during the predetermined time period, then issuing a pollution fault message. Preferably, the detected light signal exhibits slight fluctuations within a first predetermined fluctuation range during the predetermined time period.

[0023] The preferred embodiments will be described below in a clear and easy-to-understand manner, with reference to the accompanying drawings, to further explain the above-mentioned characteristics, technical features, advantages and implementation methods of the switching device. Attached Figure Description

[0024] The following figures are for illustrative purposes only and do not limit the scope of the invention.

[0025] Figure 1 A flowchart of an existing method for reporting pollution fault messages is shown.

[0026] Figure 2 A structural block diagram of an optical smoke detector according to an embodiment of the present invention is shown.

[0027] Figure 3A and Figure 3B The waveforms of the detected light signals under pollution and fire alarm conditions are shown respectively, as well as schematic diagrams of threshold criteria and fluctuation range criteria according to an embodiment of the present invention.

[0028] Figure 4 A flowchart of a method for reporting pollution fault messages according to an embodiment of the present invention is shown.

[0029] Figure 5A and Figure 5B Waveforms of the detection light signal under pollution and fire alarm conditions are shown, as well as schematic diagrams of threshold criteria and fluctuation range criteria according to another embodiment of the present invention.

[0030] Figure 6 A flowchart of a method for reporting pollution fault messages according to another embodiment of the present invention is shown.

[0031] Figure 7A and Figure 7B The diagrams show the waveforms of light signal changes and temperature signal changes under fire alarm conditions, as well as schematic diagrams of threshold criteria and fluctuation range criteria according to another embodiment of the present invention.

[0032] Figure 8 A flowchart of a method for reporting pollution fault messages according to yet another embodiment of the present invention is shown.

[0033] Figure Labels

[0034] 10: Particles; 20: Gas;

[0035] 200: Smoke detector; 210: Detection cavity; 220: Light source; 230: Light receiver;

[0036] 240: Controller; 250: Temperature sensor;

[0037] Th: Threshold; S: Optical signal; T: Temperature; R1, R2, R3: Fluctuation range;

[0038] T4: Temperature Difference Threshold Detailed Implementation

[0039] To provide a clearer understanding of the technical features, objectives, and effects of the invention, specific embodiments of the invention are now described with reference to the accompanying drawings. In the drawings, the same reference numerals indicate components with the same or similar structures but the same function.

[0040] In this document, “illustrative” means “serving as an example, illustration or description”, and any illustration or implementation described herein as “illustrative” should not be construed as a more preferred or advantageous technical solution.

[0041] To keep the drawings concise, only the parts relevant to the invention are shown schematically in each figure, and they do not represent the actual structure of the product. Furthermore, for ease of understanding, in some figures, only one of the components with the same structure or function is shown schematically, or only one is labeled.

[0042] In this article, "one" can mean not only "only one" but also "more than one". Furthermore, in this article, "first", "second", etc., are used only to distinguish them from each other, not to indicate their importance or order.

[0043] Figure 2 An exemplary structure of an optical smoke detector according to an embodiment of the present invention is shown. Figure 2 As shown, the smoke detector 200 includes a detection cavity 210, at least one light source 220, at least one light receiver 230, and a controller 240.

[0044] The detection chamber 210 has an opening communicating with the external space. Gas 20 (e.g., air or smoke) outside the detection chamber 210 can diffuse into the detection chamber 210 through these openings. The gas entering the detection chamber 210 may contain certain particles 10, the properties of which determine whether it is smoke caused by a fire. For example, if the particles 10 are water vapor, the gas is mist; if the particles 10 are solid particles and reach a certain size and density, it may be smoke caused by a fire.

[0045] Light source 220 is configured to direct light into detection cavity 210. Light source 220 may be, for example, an LED element. When gas containing particles is present within detection cavity 210, the light emitted by light source 220 is scattered by the particles in the gas. The scattered light is received and sensed by photoreceiver 230 placed within detection cavity 210. Photoreceiver 230 may be a photosensitive element, such as a photodiode. Figure 2 The example shown illustrates only one light source 220 and one light receiver 230. In other applications, the smoke detector 200 may also have, for example, two or more light sources 220, or two or more light receivers 230. The wavelengths of the light emitted by the multiple light sources 220 may be different from each other, and the multiple light receivers 230 may each be sensitive to different wavelengths of scattered light.

[0046] Figure 2 In this configuration, both the light source 220 and the light receiver 230 are connected to the controller 240. The controller 240 controls the timing or sequence of light emission from the light source 220 and collects the light signal S detected by the light receiver 230. Typically, if the controller 240 determines that the collected light signal S is greater than a fire alarm threshold Th, it reports a fire alarm ALARM.

[0047] like Figure 2 As shown, optionally, the smoke detector 200 may also include a temperature sensor 250. This temperature sensor 250 is also connected to the controller 240, which acquires the temperature T sensed by the temperature sensor 250 and determines whether a fire has occurred based on the temperature gradient change of T. For smoke detectors with both temperature and light sensing functions, the temperature sensor 250 is used to sense the temperature T inside or near the detection chamber to trigger a temperature-sensitive fire alarm. For purely light-sensitive smoke detectors, the temperature sensor 250 can be placed inside the smoke detector, for example, to sense the temperature on a printed circuit board, or it can be placed on the surface of the smoke detector to sense the ambient temperature. If the temperature gradient detected by these temperature sensors is greater than a predetermined temperature difference threshold, it also indicates a fire. The temperature gradient change can be used as an auxiliary criterion along with the light signal criterion for fire alarm determination.

[0048] exist Figure 2 In the smoke detector 200 shown, the controller 240 collects the optical signal S detected by the optical receiver 230. The inventors of this invention have carefully analyzed the characteristics of the optical signal S within a period P after the smoke detector is powered on. The time period P mentioned here is generally between 30s and 180s after power-on, preferably between 50s and 110s, and more preferably 60s or 100s. Figure 3A and Figure 3B The waveforms of the optical signal S are shown in the diagrams for pollution and fire alarm conditions, respectively. Figure 3A As shown, in situations such as severe dust pollution, the light signal S quickly exceeds a predetermined threshold Th after power-on, which can be the same as the fire alarm threshold. Simultaneously, the light signal S remains largely stable within the time period P after power-on, exhibiting only minor fluctuations, with the fluctuation range, for example, within... Figure 3A The fluctuation range R1 is shown. Assuming a fire occurs when the smoke detector 200 is powered on, the waveform of the light signal S is as follows: Figure 3B As shown. By Figure 3B As can be seen, after power-on and initialization, the optical signal S quickly exceeds the threshold Th, and exhibits significant fluctuations within the time period P; for example, the fluctuation amount ΔS of the optical signal S is greater than the fluctuation range R1. Here, the fluctuation range R1 can be, for example, approximately ±8%. (Comparison) Figure 3A and Figure 3B The inventors of this invention propose that fluctuations in the optical signal S can distinguish between pollution faults and fire alarms. For simplicity, the time period P shown in the figure is a predetermined time period after initialization. Since the time from power-on to initialization completion of the smoke detector is relatively fixed, the time period P in the figure can also be understood as a predetermined time period after power-on.

[0049] Figure 4 An exemplary flowchart of a method for reporting pollution faults according to an embodiment of the present invention is shown. Figure 4 The method shown can be derived from Figure 2 The controller 240 in the system executes this. For example... Figure 4 As shown, the method flow begins with step S110. In step S110, the smoke detector 200 is powered on. In step S120, the controller 240 completes the initialization process. After initialization, in step S130, the controller 240 acquires the detected light signal S from the light receiver 230 within a time period P. Then, in step S140, it is determined whether the light signal S is greater than a threshold Th. The threshold Th can be a threshold used to report a fire alarm. If the light signal S is less than the threshold Th, it indicates that the dust in the current detection chamber is not severe and there is no fire, and the process proceeds to step S190, entering normal operation. Here, normal operation refers to the routine operation of the smoke detector during operation, such as monitoring the dust status and enabling the dust compensation algorithm.

[0050] Figure 4 If, in step S140, the optical signal S is determined to be greater than the threshold Th, it indicates either a fire alarm or a pollution fault. To distinguish between a pollution fault and a fire alarm, the process proceeds to step S450. In step S450, the controller 240 further determines whether the fluctuation amount ΔS of the optical signal S exceeds a predetermined fluctuation range R1. If the optical signal S exhibits small fluctuations, for example... Figure 3A As shown, if the fluctuation amount ΔS falls within the fluctuation range R1 within the time period P, it indicates that the optical signal S is greater than the threshold Th due to dust or contamination, and the process proceeds to step S460. In step S460, the controller 240 reports a contamination fault message FAULT. Conversely, if the optical signal S exhibits significant fluctuations, such as... Figure 3B As shown, if the fluctuation amount ΔS exceeds the fluctuation range R1, it indicates that the light signal S is greater than the threshold Th due to smoke, and the process proceeds to step S480. In step S480, the controller 240 reports a fire alarm message ALARM. Optionally, step S480 can be omitted; that is, if it is determined in step S450 that ΔS exceeds the fluctuation range R1, the process directly proceeds to step S190 for normal operation. In this case, during normal operation, since the light signal S is greater than the fire alarm threshold Th, the controller 240 reports a fire alarm message ALARM.

[0051] exist Figure 4 In the illustrated method, the controller 240 not only determines a fire alarm based on whether the detected light signal S is greater than the threshold Th, but also further distinguishes between pollution faults and fire alarms based on whether the light signal S shows significant fluctuations within a predetermined time period P after power-on. Figure 4 The method shown allows the smoke detector 200 to promptly report a pollution fault message upon power-on, and it can also promptly report a fire alarm if a fire occurs during power-on, without interference from pollution. Therefore, the method employed... Figure 4 The method shown can successfully pass the dust test mentioned earlier.

[0052] To increase the accuracy of pollution fault diagnosis, the inventors of this invention further propose to adopt the following... Figure 5A and 5B The judgment method with dual fluctuation range criterion shown is illustrated in the flowchart below. Figure 6 shown. Specifically, Figure 5A and Figure 5B Waveforms of the optical signal S are shown under pollution and fire conditions, respectively. Figure 5AAs shown, in cases of severe dust pollution, after the smoke detector is powered on and initializes, the optical signal S quickly exceeds the fire alarm threshold Th. Simultaneously, the optical signal S exhibits slight fluctuations within the initialization time period P, meaning the fluctuation amount ΔS falls within the fluctuation range R2. Here, the fluctuation range R2 is preferably less than ±8%, more preferably less than or equal to ±5%, and particularly preferably equal to 2%. Figure 5B As shown, if a fire occurs upon power-up, the optical signal S will quickly exceed the threshold Th. Simultaneously, within the initial time period P, the optical signal S exhibits significant fluctuations, for example, its fluctuation amount ΔS is greater than the fluctuation range R3. Here, the fluctuation range R3 is greater than the fluctuation range R2. The fluctuation range R3 can be, for example, greater than ±8%, or even greater than or equal to ±10%.

[0053] Figure 6 An exemplary method for reporting pollution faults according to another embodiment of the present invention is shown, wherein such method is utilized. Figure 5A and 5B The dual fluctuation range criterion is shown. Figure 6 In the process flow, steps S110 to S140, S190, S460, and S480 are consistent with... Figure 4 The steps shown are the same, and will not be repeated here. Figure 4 Unlike step S140, if the optical signal S is greater than the threshold Th, the process proceeds to step S650. In step S650, the controller 240 further determines whether the fluctuation amount ΔS of the optical signal S exceeds a small predetermined fluctuation range R2. If the optical signal S exhibits relatively small fluctuations, for example... Figure 5A If the fluctuation amount ΔS is within the fluctuation range R2, it indicates that the light signal S exceeding the threshold Th is caused by dust or pollution, and the process proceeds to step S460. In step S460, the controller 240 reports a pollution fault message FAULT. Conversely, if the fluctuation amount ΔS of the light signal S exceeds the fluctuation range R2, the process proceeds to step S670. In step S670, the controller 240 further determines whether the fluctuation amount ΔS of the light signal exceeds a larger fluctuation range R3. If it does, it indicates that the light signal S exceeding the threshold Th is caused by smoke, and the process proceeds to step S480. In step S480, the controller 240 reports a fire alarm message ALARM. If the fluctuation amount ΔS of the light signal S falls exactly between the fluctuation ranges R2 and R3, an optional processing method is to repeat steps S140 to S670 after a certain interval. If it is a fire alarm, ΔS will inevitably exceed the fluctuation range R3 after a period of time. If it is pollution, ΔS will inevitably fall back into the fluctuation range R2 after a period of stabilization.

[0054] exist Figure 6In the illustrated method flow, the controller 240 uses dual fluctuation ranges R2 and R3 as criteria to distinguish between pollution faults and fire alarms. Using the dual fluctuation range criterion, a pollution fault is only identified when the fluctuation of the optical signal S is minimal (within fluctuation range R2), and a fire alarm is only identified when the fluctuation of the optical signal S is significant (greater than fluctuation range R3). Thus, compared to a single fluctuation range criterion R1, the dual fluctuation range criterion is more accurate in distinguishing between pollution faults and fire alarms, further reducing false alarms and missed fire alarms.

[0055] To further reduce fire alarm false alarms, the inventors of this invention propose using temperature gradient as an additional criterion to distinguish between pollution faults and fire alarms. Figure 7A and Figure 7B The waveforms of the light signal S detected by the light receiver and the temperature T sensed by the temperature sensor are shown respectively in a fire alarm situation. Figure 7A As shown, for example, in the case of burning organic materials such as plastics or burning wood, the fluctuation of the light signal S in the early stages of a fire may not be obvious, and the fluctuation amount ΔS is likely to fall between, for example, fluctuation ranges R2 and R3. In this case, a temperature gradient can be further introduced as an auxiliary criterion. Figure 7B As shown, within time period P, if it is a fire, the temperature T increases rapidly, and its temperature increment ΔT is greater than the temperature difference threshold T4. Conversely, if it is pollution, the temperature T hardly changes. Here, the temperature difference threshold T4 is preferably the fire alarm threshold of the temperature sensor, preferably greater than or equal to 8℃, and more preferably greater than or equal to 10℃.

[0056] Figure 8 An exemplary method for reporting pollution faults by incorporating a temperature gradient criterion according to yet another embodiment of the present invention is shown. Figure 8 Steps S110 to S670, S460, 480 and S190 in the text are related to... Figure 6 The content shown is the same, so it will not be repeated here. Figure 6 Unlike step S670, if the fluctuation amount ΔS of the optical signal S falls exactly between the fluctuation range R2 and the fluctuation range R3, the process proceeds to step S875. In step S875, it is determined whether the temperature difference ΔT detected by the temperature sensor 250 within the time period P exceeds a predetermined temperature difference threshold T4. If it does, then... Figure 7B As shown, this indicates a fire has occurred, and the process proceeds to step S480. In step S480, the controller 240 reports a fire alarm message ALARM. In step S875, if the temperature difference ΔT does not exceed the temperature difference value T4, the process proceeds to step S460 to report a pollution fault FAULT.

[0057] Figure 8The example shown combines the dual fluctuation range criterion with the temperature gradient criterion. Alternatively, the temperature gradient criterion can also be combined with... Figure 4 The single fluctuation range criterion shown is combined. That is, when the fluctuation amount ΔS of the optical signal S is less than the fluctuation range R1, it can be further determined that the temperature difference ΔT within the time period P does not exceed the temperature difference value T4. If it does exceed, a fire alarm message ALARM is reported; otherwise, it is determined to be a pollution fault.

[0058] For fires with minimal initial light signal fluctuations, the introduction of a temperature gradient criterion can further reduce missed fire alarms. Preferably, the temperature sensor 250 is an existing component on the smoke detector, thus not increasing the hardware cost or complexity of the smoke detector.

[0059] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0060] The detailed descriptions listed above are merely specific descriptions of feasible embodiments of the present invention and are not intended to limit the scope of protection of the present invention. All equivalent implementation schemes or modifications made without departing from the spirit of the present invention, such as combinations, divisions or repetitions of features, should be included within the scope of protection of the present invention.

Claims

1. A smoke detector, comprising: A detection chamber (210) is adapted to receive gas containing particles (10) from outside the smoke detector; At least one light source (220) is adapted to direct light into the detection cavity (210). At least one optical receiver (230) detects the light signal (S) formed by scattering from the particles (10) within the detection cavity (210); A controller (240) is connected to the light source (220) and the light receiver (230) and is configured to: Within a predetermined time period (P) after power-on, if it is determined that the light signal (S) detected by the optical receiver (230) is less than a predetermined threshold (Th), then normal operation is initiated, which includes monitoring dust conditions and enabling a dust compensation algorithm; and If, during the predetermined time period (P) after power-on, it is determined that the light signal (S) detected by the light receiver (230) is greater than the predetermined threshold (Th), and the detected light signal (S) exhibits slight fluctuations within a first predetermined fluctuation range (R1, R2) during the predetermined time period (P), a contamination fault (FAULT) message is issued.

2. The smoke detector as described in claim 1, wherein, The controller (240) is further configured to: within a predetermined time period (P) after power-on, if it is determined that: The optical signal (S) detected by the optical receiver (230) is greater than the predetermined threshold (Th), and The detected optical signal (S) exceeded the first predetermined fluctuation range (R1) within the predetermined time period (P) after power-on. Then an ALARM message will be sent.

3. The smoke detector as described in claim 1, wherein, The controller (240) is also configured to determine, within a predetermined time period (P) after power-on: The optical signal (S) detected by the optical receiver (230) is greater than the predetermined threshold (Th), and The detected optical signal (S) exceeded a second predetermined fluctuation range (R3) during the predetermined time period (P) after power-on. Then a fire alarm (ALARM) message will be issued. The second predetermined fluctuation range (R3) is greater than the first predetermined fluctuation range (R2).

4. The smoke detector as claimed in claim 2 further includes a temperature sensor (250) that detects the temperature (T) inside or near the detection cavity (210), and, The controller (240) is further configured to, within a predetermined time period (P) after power-on, if it is determined that: The optical signal (S) detected by the optical receiver (230) is greater than the predetermined threshold (Th). The detected optical signal (S) is less than the first predetermined fluctuation range (R1) within the predetermined time period (P) after power-on, and, The temperature sensor (250) experiences a temperature increase exceeding a predetermined temperature difference threshold (T4) within a predetermined time period (P) after power-on. Then an ALARM message will be sent.

5. The smoke detector of claim 3 further includes a temperature sensor (250) that detects the temperature inside or near the detection cavity (210), and, The controller (240) is also configured to determine, within a predetermined time period (P) after power-on: The optical signal (S) detected by the optical receiver (230) is greater than the predetermined threshold (Th). The detected optical signal (S) is greater than the first predetermined fluctuation range (R2) but less than a second predetermined fluctuation range (R3) during the predetermined time period (P), and, The temperature sensor (250) experiences a temperature increase exceeding a predetermined temperature difference threshold (T4) within the predetermined time period (P). Then an ALARM message will be sent.

6. The smoke detector as described in claim 4 or 5, wherein, The threshold (Th) is the alarm threshold for a fire alarm, or the predetermined temperature difference threshold (T4) is the temperature threshold for a fire alarm.

7. The smoke detector as described in claim 5, wherein, The first predetermined fluctuation range (R1, R2) is less than or equal to ±8%; The second predetermined fluctuation range (R3) is greater than or equal to ±8%; The predetermined temperature difference threshold (T4) is greater than or equal to 8°C.

8. The smoke detector as described in claim 7, wherein, The first predetermined fluctuation range (R1, R2) is less than or equal to ±5%; or The second predetermined fluctuation range (R3) is greater than or equal to ±10%; or The predetermined temperature difference threshold (T4) is greater than or equal to 10°C.

9. The smoke detector as described in claim 7, wherein, The first predetermined fluctuation range (R1, R2) is equal to 2%.

10. The smoke detector according to any one of claims 1-5, wherein, The predetermined time period (P) is between 2s and 180s.

11. The smoke detector as claimed in claim 10, wherein, The predetermined time period (P) is from 50s to 110s.

12. The smoke detector as claimed in claim 10, wherein, The predetermined time period (P) is 60s or 100s.

13. A method for reporting a pollution fault using an optical smoke detector, comprising: The light signal (S) is detected within a predetermined time period (P) after the smoke detector is powered on. If, within a predetermined time period (P) after power-on, the detected light signal (S) is determined to be less than a predetermined threshold (Th), then normal operation is initiated, which includes monitoring dust status and enabling a dust compensation algorithm. If, within a predetermined time period (P) after power-on, it is determined that the detected light signal (S) is greater than the predetermined threshold (Th), and the detected light signal (S) exhibits slight fluctuations within a first predetermined fluctuation range (R1, R2) during the predetermined time period (P), a contamination fault (FAULT) message is issued.

14. The method of claim 13, further comprising: If, during the predetermined time period (P) after power-on, the detected light signal (S) is greater than the predetermined threshold (Th), and the detected light signal (S) exceeds a second predetermined fluctuation range (R3) during the predetermined time period (P), then an ALARM message is issued, wherein the second predetermined fluctuation range (R3) is greater than the first predetermined fluctuation range (R2).

15. The method of claim 14, wherein, Also includes: Detecting the temperature inside or near the detection cavity (210) of the smoke detector, and If, during the predetermined time period (P) after power-on, the detected light signal (S) is greater than the predetermined threshold (Th), the detected light signal (S) is greater than the first predetermined fluctuation range (R2) but less than the second predetermined fluctuation range (R3) during the predetermined time period (P), and the temperature increase during the predetermined time period (P) exceeds a predetermined temperature difference threshold (T4), then an ALARM message is issued.

16. The method of claim 15, wherein, The threshold (Th) is the alarm threshold for a fire alarm; The predetermined temperature difference threshold (T4) is the temperature threshold for fire alarm; The first predetermined fluctuation range (R1, R2) is less than or equal to ±8%; The second predetermined fluctuation range (R3) is greater than or equal to ±8%; or The predetermined temperature difference threshold (T4) is greater than or equal to 8°C.

17. The method of claim 16, wherein, The first predetermined fluctuation range (R1, R2) is less than or equal to ±5%; or The second predetermined fluctuation range (R3) is greater than or equal to ±10%; or The predetermined temperature difference threshold (T4) is greater than or equal to 10°C.

18. The method of claim 16, wherein, The first predetermined fluctuation range (R1, R2) is equal to 2%.

19. A smoke detector, comprising: A detection chamber (210) is adapted to receive gas containing particles (10) from outside the smoke detector; At least one light source (220) is adapted to direct light into the detection cavity (210). At least one optical receiver (230) detects the light signal (S) formed by scattering from the particles (10) within the detection cavity (210); A controller (240) is connected to the light source (220) and the light receiver (230) and is configured to: If, within a predetermined time period (P) after the smoke detector is powered on, it is determined that the light signal (S) detected by the light receiver (230) is greater than a predetermined threshold (Th), and the detected light signal (S) exhibits slight fluctuations within a first predetermined fluctuation range (R1, R2) during the predetermined time period (P), a pollution fault (FAULT) message is issued. and If, within a predetermined time period (P) after the smoke detector is powered on, it is determined that the light signal (S) detected by the light receiver (230) is greater than the predetermined threshold (Th), and the detected light signal (S) exceeds the first predetermined fluctuation range (R1, R2) within the predetermined time period (P), then the pollution fault (FAULT) information will not be issued, but a fire alarm (ALARM) message will be issued. The predetermined time period (P) after power-on occurs before the smoke detector enters normal operation, which includes monitoring dust status and enabling a dust compensation algorithm.

20. The smoke detector as claimed in claim 19, wherein, The controller (240) is also configured to determine, within a predetermined time period (P) after power-on: The optical signal (S) detected by the optical receiver (230) is greater than the predetermined threshold (Th), and If the detected optical signal (S) exceeds a second predetermined fluctuation range (R3) during the predetermined time period (P) after power-on, an ALARM message is issued. The second predetermined fluctuation range (R3) is greater than the first predetermined fluctuation range (R2).

21. The smoke detector of claim 19, further comprising a temperature sensor (250) that detects the temperature (T) within or near the detection cavity (210), and, The controller (240) is further configured to, within a predetermined time period (P) after power-on, if it is determined that: The optical signal (S) detected by the optical receiver (230) is greater than the predetermined threshold (Th). The detected optical signal (S) is less than the first predetermined fluctuation range (R1) within the predetermined time period (P) after power-on, and, The temperature sensor (250) experiences a temperature increase exceeding a predetermined temperature difference threshold (T4) within a predetermined time period (P) after power-on. Then an ALARM message will be sent.

22. The smoke detector of claim 20, further comprising a temperature sensor (250) that detects the temperature inside or near the detection cavity (210), and, The controller (240) is also configured to determine, within a predetermined time period (P) after power-on: The optical signal (S) detected by the optical receiver (230) is greater than the predetermined threshold (Th). The detected optical signal (S) is greater than the first predetermined fluctuation range (R2) but less than a second predetermined fluctuation range (R3) during the predetermined time period (P), and, The temperature sensor (250) experiences a temperature increase exceeding a predetermined temperature difference threshold (T4) within the predetermined time period (P). Then an ALARM message will be sent.

23. The smoke detector as claimed in claim 21 or 22, wherein, The threshold (Th) is the alarm threshold for a fire alarm, or the predetermined temperature difference threshold (T4) is the temperature threshold for a fire alarm.

24. The smoke detector as claimed in claim 22, wherein, The first predetermined fluctuation range (R1, R2) is less than or equal to ±8%; The second predetermined fluctuation range (R3) is greater than or equal to ±8%; The predetermined temperature difference threshold (T4) is greater than or equal to 8°C.

25. The smoke detector as claimed in claim 24, wherein, The first predetermined fluctuation range (R1, R2) is less than or equal to ±5%; or The second predetermined fluctuation range (R3) is greater than or equal to ±10%; or The predetermined temperature difference threshold (T4) is greater than or equal to 10°C.

26. The smoke detector as claimed in claim 24, wherein, The first predetermined fluctuation range (R1, R2) is equal to 2%.

27. The smoke detector as described in any one of claims 19-22, wherein, The predetermined time period (P) is between 2s and 180s.

28. The smoke detector as claimed in claim 27, wherein, The predetermined time period (P) is from 50s to 110s.

29. The smoke detector as claimed in claim 27, wherein, The predetermined time period (P) is 60s or 100s.

30. A method for reporting a pollution fault using an optical smoke detector, comprising: The light signal (S) is detected within a predetermined time period (P) after the smoke detector is powered on. If, within a predetermined time period (P) after power-on, the detected light signal (S) is greater than a predetermined threshold (Th), and the detected light signal (S) exhibits slight fluctuations during the predetermined time period (P), a contamination fault (FAULT) message is issued. If, within the predetermined time period (P) after power-on, the detected light signal (S) is greater than the predetermined threshold (Th) and exceeds the first predetermined fluctuation range (R1, R2) within the predetermined time period (P) after power-on, the pollution fault (FAULT) message will not be issued but the fire alarm (ALARM) message will be issued. The predetermined time period (P) after power-on is before the smoke detector enters normal operation, which includes monitoring dust status and enabling a dust compensation algorithm.

31. The method of claim 30, further comprising: If, during the predetermined time period (P) after power-on, the detected light signal (S) is greater than the predetermined threshold (Th), and the detected light signal (S) exceeds a second predetermined fluctuation range (R3) during the predetermined time period (P), then an ALARM message is issued, wherein the second predetermined fluctuation range (R3) is greater than the first predetermined fluctuation range (R2).

32. The method of claim 31, wherein, Also includes: Detecting the temperature inside or near the detection cavity (210) of the smoke detector, and If, during the predetermined time period (P) after power-on, the detected light signal (S) is greater than the predetermined threshold (Th), the detected light signal (S) is greater than the first predetermined fluctuation range (R2) but less than the second predetermined fluctuation range (R3) during the predetermined time period (P), and the temperature increase during the predetermined time period (P) exceeds a predetermined temperature difference threshold (T4), then an ALARM message is issued.

33. The method of claim 32, wherein, The threshold (Th) is the alarm threshold for a fire alarm; The predetermined temperature difference threshold (T4) is the temperature threshold for fire alarm; The first predetermined fluctuation range (R1, R2) is less than or equal to ±8%; The second predetermined fluctuation range (R3) is greater than or equal to ±8%; or The predetermined temperature difference threshold (T4) is greater than or equal to 8°C.

34. The method of claim 33, wherein, The first predetermined fluctuation range (R1, R2) is less than or equal to ±5%; or The second predetermined fluctuation range (R3) is greater than or equal to ±10%; or The predetermined temperature difference threshold (T4) is greater than or equal to 10°C.

35. The method of claim 33, wherein, The first predetermined fluctuation range (R1, R2) is equal to 2%.

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