Smoke detector

Abstract

The present invention aims to reduce the adverse situation in which a smoke sensor generates useless log data representing substantially the same value in generating log data representing the measured value of a flow meter. A flow meter (115) measures the flow rate of air flowing into the sensing region of the smoke sensor from the outside space. A flow signal acquisition unit (1183) of a control unit (118) possessed by the smoke sensor acquires a flow signal representing the measured value of the flow meter (115), and a storage unit (1180) temporarily stores the flow signal in a flow temporary storage table. A log generation unit (1184) generates log data representing the measured value of the flow at that time in the case where the rate of change of the measured value of the flow stored in the flow temporary storage table is determined to reach a set air flow change step value, and the storage unit (1180) appends the log data to a flow log table. A threshold value change unit (1187) changes the set air flow change step value in accordance with a prescribed operation of a button (116) by a user.

Description

Technical Field

[0001] This invention relates to smoke sensing technology. Background Technology

[0002] There exists a smoke sensor that senses the generation of smoke in the external space by sensing the particles contained in the air flowing into the sensing area from the external space.

[0003] For example, a smoke sensor called a photoelectric smoke sensor emits light from a light-emitting element into a sensing area. The light is then received by a light-receiving element, which receives the scattered light after it has been scattered by particles in the air within the sensing area. Based on the intensity of the light received and measured by the light-receiving element, the sensor detects the particles contained in the air flowing into the sensing area from the outside space, thereby detecting the generation of smoke in the outside space.

[0004] Patent document 1 discloses a technology related to photoelectric smoke sensors. In the photoelectric smoke sensor described in Patent Document 1, attention is paid to the fact that the output signal of the light-receiving element changes over time differently when non-smoke particles such as hot air flow into the smoke detection space (sensing area) and when smoke flows into the smoke detection space. The invention proposes to avoid the undesirable situation of falsely sensing smoke due to the generation of hot air by delaying the output signal from the light-receiving element by a predetermined delay time.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2019-61423 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] Like photoelectric smoke sensors, most smoke sensors (hereinafter referred to as "smoke sensors") detect the generation of smoke in the external space by sensing particles contained in the air flowing into the sensing area from the external space. To prevent dust particles larger than smoke particles from entering the sensing area and adhering as contaminants to the light-emitting element, light-receiving element, etc., a filter of varying mesh sizes—allowing smoke to pass through but preventing dust—is installed in the airflow path from the external space towards the sensing area. If this filter becomes clogged or damaged for any reason, the photoelectric smoke sensor cannot accurately detect smoke generated in the external space. Furthermore, sometimes dust or other particles adhere to the inner walls of pipes or other structures forming the airflow path from the external space towards the sensing area, obstructing airflow. In this case, the photoelectric smoke sensor also cannot accurately detect smoke generated in the external space.

[0010] To detect the occurrence of such anomalies, consider setting up a flow meter to measure the flow rate of air flowing into the sensing area from the external space, and a structure to monitor whether the air flow rate measured by the flow meter is within an appropriate range. In such a structure, the data representing the flow meter's measurement results is stored as log data, and the temporal changes in air flow rate are analyzed. This allows for the estimation of the cause when the air flow rate is outside the appropriate range, or the estimation of the period during which the air flow rate is outside the appropriate range.

[0011] For example, if the flow meter's measurement results are stored as log data at predetermined intervals, useless log data representing substantially the same values ​​will be generated during periods when the airflow remains almost unchanged. For instance, when storing log data within a smoke sensor, it's undesirable to store useless log data in a storage area with limited capacity. Furthermore, when log data is sent from the smoke sensor to and stored in a higher-level system, it's undesirable to increase data communication volume due to useless log data. Additionally, if there is a large amount of log data representing substantially the same values, it's not preferable to spend excessive time on verification by maintenance personnel.

[0012] Therefore, new log data is generated whenever the rate of change of flow measured by the flow meter (the absolute value of the change in flow since the last log data generation, divided by the flow rate at the last log data generation time) reaches a predetermined threshold, thereby reducing the generation of useless log data. Hereinafter, the threshold for the rate of change of flow used as a condition for generating log data will be referred to as the "airflow change step value".

[0013] Furthermore, the rate of change of airflow from the external space into the sensing area of ​​the smoke sensor largely varies depending on whether the flow rate is low or high. For example, the lower the flow rate, the larger the rate of change, even for small changes in flow. Therefore, in the case of low flow, the rate of change frequently reaches the airflow change step value, resulting in undesirable situations such as generating useless log data.

[0014] In view of this situation, the present invention provides a means to reduce the undesirable situation where a smoke sensor generates useless log data representing substantially the same value when generating log data representing the measured value of a flow meter.

[0015] Methods for solving problems

[0016] To address the aforementioned problems, the present invention provides a smoke sensor that detects the generation of smoke in the external space by sensing particles contained in the air flowing into the sensing area from the external space. The smoke sensor comprises: a flow rate measuring unit that measures the air flow rate; a log generation unit that generates log data representing the measured values ​​when the rate of change of the flow rate measuring unit reaches a threshold; and a threshold changing unit that changes the threshold value.

[0017] Invention Effects

[0018] According to the present invention, by changing the airflow change step value to an appropriate value based on the airflow rate flowing into the sensing area from the external space, log data representing the measured values ​​of the flow measurement unit can be generated at an appropriate frequency. As a result, undesirable situations such as generating useless log data representing substantially the same values ​​can be reduced. Attached Figure Description

[0019] Figure 1 This is a diagram showing the structure of a smoke sensing system according to one embodiment.

[0020] Figure 2 This is a schematic diagram illustrating the structure of a smoke sensor according to one embodiment.

[0021] Figure 3 This is a diagram illustrating the structure of a computer used as the hardware of a control unit in one implementation.

[0022] Figure 4 This is a diagram illustrating the functional structure of a control unit in one embodiment.

[0023] Figure 5 This is a diagram illustrating the structure of an airflow change step value table in one embodiment.

[0024] Figure 6 This is a diagram illustrating the structure of a traffic temporary storage table in one implementation.

[0025] Figure 7 This is a diagram illustrating the structure of a traffic log table in one implementation.

[0026] Figure 8 This is a diagram illustrating the structure of a modified example of an airflow change step value table. Detailed Implementation

[0027] The following describes a smoke sensing system 1 according to one embodiment of the present invention. Figure 1 This is a diagram showing the structure of the smoke sensing system 1. The smoke sensing system 1 has a smoke sensor 11 and a host system 12.

[0028] The smoke sensor 11 is a device that is configured in the space of the monitored object that generates smoke (hereinafter referred to as the "monitoring space"), takes in the air in the monitoring space, and if the taken-in air contains smoke, it detects the smoke and sends an alarm for smoke generation to the upper system 12 when smoke is detected.

[0029] exist Figure 1 In the smoke sensing system 1, the number of smoke sensors 11 is one, but the number of smoke sensors 11 in the smoke sensing system 1 varies depending on the number and area of ​​the monitored space.

[0030] The host system 12 can be any of a monitoring terminal device, a smoke alarm panel, a central monitoring system, etc. The host system 12 and the smoke sensor 11 are connected via a wired, wireless, or hybrid communication medium and can communicate with each other.

[0031] The host system 12 is the same as the host system in the prior art, so its description is omitted.

[0032] Figure 2 This is a schematic diagram showing the structure of a smoke sensor 11. The smoke sensor 11 includes a housing 110, a light-emitting part 111, a light-receiving part 112, a fan 113, a filter 114, a flow meter 115, a button 116, a light-emitting part 117, and a control unit 118.

[0033] The housing 110 is a container that forms a space inside. The housing 110 has an opening, namely an intake port P, which functions as an inlet for air to flow from the outside space to the inside space, and an opening, namely an exhaust port Q, which functions as an outlet for air to flow from the inside space to the outside space.

[0034] Additionally, the housing 110 includes: a wall 1101 for forming a sensing area S for sensing smoke within the interior space; a pipe 1102 for forming an airflow path from the intake port P to the sensing area S; and a pipe 1103 for forming an airflow path from the sensing area S to the exhaust port Q.

[0035] The light-emitting unit 111, for example, has an LED, from which light is emitted into the sensing area S. The light-receiving unit 112 is positioned not opposite the light-emitting unit 111, such that the light emitted from the light-emitting unit 111 is not directly incident, but is instead incident as scattered light from particles in the air within the sensing area S. The light-receiving unit 112, for example, has a photodiode, which receives a portion of the scattered light within the sensing area S and outputs a light intensity signal representing the intensity of the received light.

[0036] The fan 113 is positioned in the airflow path formed by the pipe 1102, and serves to generate airflow from the external space toward the sensing area S through rotating blades.

[0037] The filter 114 is configured in the airflow path formed by the pipe 1102 to capture dust contained in the air flowing from the outside space toward the sensing area S, and to prevent dust from entering the sensing area S.

[0038] Flow meter 115 (an example of a flow measurement unit) is a sensor that measures the flow rate of air flowing from the external space into the sensing area S through the operation of fan 113. Flow meter 115 may have, for example, a thermistor, and the air flow rate is determined based on the resistance value of the thermistor, which changes with the air flow rate. However, the way flow meter 115 measures air flow rate is not limited to this, and various known types of flow meters may be used as flow meter 115.

[0039] Button 116 (an example of an operation receiving unit) is an operating component that receives operations from users (such as the administrator of the smoke sensing system 1). Button 116 is operated when the user changes a set airflow change step value (an example of a threshold).

[0040] The light-emitting unit 117 is a structural part that serves to notify the user that the user's operation on the button 116 has been accepted. The light-emitting unit 117 has, for example, an LED, which illuminates once when the airflow change step value is set to 10%, twice when it is set to 20%, and three times when it is set to 30%, depending on the user's operation on the button 116. By illuminating the LED in different ways corresponding to the set value of the airflow change step value, the setting value is notified to the user.

[0041] exist Figure 2 In this configuration, button 116 and light-emitting part 117 are disposed on the outer surface of housing 110, but their placement is not limited to this. For example, if housing 110 has an openable and closable cover, button 116 can be disposed in a position within the interior space of housing 110 where the user can press it when the cover is open, and light-emitting part 117 can be disposed in a position within the interior space of housing 110 where the user can visually confirm it when the cover is open. In this case, the undesirable situation of changing the set value of the airflow change step value due to unintentional operation by the user is avoided.

[0042] The control unit 118 is a device that controls the operation of the smoke sensor 11. The hardware of the control unit 118 is, for example, a computer, which processes the program used by the control unit 118, thereby implementing the control unit 118.

[0043] Figure 3This diagram shows the structure of the computer 10 used as the hardware of the control unit 118. The computer 10 has a processor 101 for performing various data processing, a memory 102 for storing various data, an input / output interface 103 for transmitting signals between the smoke sensor 11 and structural parts such as the light-emitting part 111, and a communication interface 104 for sending and receiving data with external devices (in this case, a host system 12).

[0044] Figure 4 This is a diagram illustrating the functional structure of the control unit 118. Specifically, the computer 10 processes the program used by the control unit 118, thereby realizing... Figure 4 The control unit 118 of the structure shown is described below. The functional structure of the control unit 118 is described below.

[0045] Storage unit 1180 stores various types of data. The data stored in storage unit 1180 includes the following data.

[0046] (1) Options for airflow change step values ​​and a table representing the airflow change step values ​​selected and set from these options (hereinafter referred to as the "airflow change step value table").

[0047] (2) A table that temporarily stores the measured value of the flow meter 115 together with the time information indicating the time when the measured value was measured (hereinafter referred to as the "flow temporary storage table").

[0048] (3) A table that stores the measured values ​​stored in the flow temporary storage table when the rate of change reaches the set airflow change step value, together with the time information indicating the time point when the measured value was measured (hereinafter referred to as the "flow log table").

[0049] (4) Thresholds used to determine whether there is an abnormal flow.

[0050] (5) Threshold used to determine whether there is smoke.

[0051] Figure 5 This is a diagram illustrating the structure of the step value table for airflow changes. Figure 5 The data in the illustrated airflow change step value table indicates that 20% is the currently selected and set airflow change step value among the three options of 10%, 20%, and 30%.

[0052] Figure 6 This is a diagram illustrating the structure of a flow rate temporary storage table. The flow rate temporary storage table has a "Time" column that stores time information indicating the moment the flow rate was measured, and a "Flow Rate" column that stores the measured flow rate at that moment. Only two records are stored in the flow rate temporary storage table.

[0053] The data in the first row of the flow temporary storage table represents the data last appended to the flow log table. Additionally, the data in the second row of the flow temporary storage table represents the last measured flow value by flowmeter 115 and the time at which that measured value was obtained. Hereinafter, the measured value stored in the "Flow" column of the first row of the flow temporary storage table will be referred to as f(1), and the measured value stored in the "Flow" column of the second row of the flow temporary storage table will be referred to as f(2).

[0054] In this embodiment, the rate of change (%) of the flow rate compared with the set airflow change step value is represented by R in Equation 1 below.

[0055] R = |f(2) - f(1)| / f(1) × 100···(Equation 1)

[0056] Additionally, |X| represents the absolute value of X.

[0057] When the rate of change R reaches the set airflow change step value, the second row of data in the flow temporary storage table is added to the bottom row of the flow log table, and the first row of data in the flow temporary storage table is deleted, with the second row becoming the new first row. Afterwards, the second row is overwritten with the data representing the latest measured value of flowmeter 115 and the time of measurement.

[0058] Figure 7 This is a diagram illustrating the structure of a flow log table. The flow log table has a "Time" column that stores time information indicating the moment when the flow measurement was taken, and a "Flow" column that stores the measured flow value at that moment. The flow log table sequentially stores data indicating the flow measurement value when the rate of change R of the airflow measured by flow meter 115 reaches the set airflow change step value, as well as the time point at which that measurement value was measured.

[0059] Reference Figure 4 The functional structure of the control unit 118 will be further explained below. The light-emitting indicator unit 1181 instructs the light-emitting unit 111 to emit light. The light intensity signal acquisition unit 1182 acquires a light intensity signal representing the intensity of the light received by the light-receiving unit 112. The light intensity signal acquired by the light intensity signal acquisition unit 1182 is used by the smoke detection unit 1186.

[0060] The flow signal acquisition unit 1183 acquires the flow signal representing the measured value of the flow meter 115. The measured value represented by the flow signal acquired by the flow signal acquisition unit 1183 is temporarily stored together with the time of acquisition in the flow temporary storage table of the storage unit 1180.

[0061] Log generation unit 1184 generates log data representing the measured values ​​when the rate of change of the measured values ​​of flow meter 115 reaches a threshold. Specifically, log generation unit 1184 calculates the rate of change R according to Equation 1 above, based on the two measured values ​​(f(1) and f(2)) stored in the flow temporary storage table of storage unit 1180, and determines whether the calculated rate of change R reaches the airflow change step value selected in the airflow change step value table. If the rate of change R reaches the selected airflow change step value, a copy of the data in the second row of the flow temporary storage table is generated as new log data, and this log data is appended to the bottom row of the flow log table. In addition, when the log generation unit 1184 appends new log data to the flow log table as described above, it deletes the data in the first row of the flow temporary storage table and uses the data in the second row as the new first row of data.

[0062] The flow anomaly determination unit 1185 determines whether the measured value in the "Flow" column of the second row of the flow temporary storage table reaches the threshold for determining flow anomalies stored in the storage unit 1180, and when the measured value reaches the threshold for determining flow anomalies, it generates flow anomaly notification data to notify of the flow anomaly. The flow anomaly notification data generated by the flow anomaly determination unit 1185 is sent to the host system 12 through the communication unit 1189.

[0063] The smoke detection unit 1186 determines whether the intensity of the light represented by the light intensity signal obtained by the light-emitting unit 1182 from the light-emitting unit 111 reaches the threshold for determining the presence or absence of smoke stored in the storage unit 1180. If the intensity reaches the threshold for determining the presence or absence of smoke, smoke generation notification data is generated. The smoke generation notification data generated by the smoke detection unit 1186 is sent to the host system 12 via the communication unit 1189.

[0064] The threshold changing unit 1187 changes the set airflow change step value. Specifically, the threshold changing unit 1187 receives an operation signal output from the button 116 based on the user's operation, and changes the record with "○" stored in the "Selection" column of the airflow change step value table in the storage unit 1180 based on the received operation signal. For example, whenever the user presses and holds the button 116, the records with "○" stored in the "Selection" column of the airflow change step value table are changed sequentially, such as record 1, record 2, record 3, record 1, ...

[0065] Whenever a record containing a "○" in the "Selection" column of the airflow change step value table changes, the light indicator unit 1188 instructs the light-emitting unit 117 to emit light in a manner corresponding to the number of the record containing the changed "○" (i.e., the newly set airflow change step value). An example of how the light-emitting unit 117 emits light according to the light indicator unit 1188 is described above.

[0066] The communication unit 1189 (an example of a sending and receiving unit) performs various data transmissions and receptions with the host system 12. Specifically, as described above, when the flow anomaly determination unit 1185 generates flow anomaly notification data, the communication unit 1189 sends the flow anomaly notification data to the host system 12. Additionally, as described above, when the smoke determination unit 1186 generates smoke generation notification data, the communication unit 1189 sends the smoke generation notification data to the host system 12.

[0067] Additionally, the communication unit 1189 receives, for example, a request to send a flow log table from the host system 12, and sends a copy of the flow log table to the host system 12 according to the request. The host system 12 or its users can, based on the data stored in the flow log table received from the smoke sensor 11 by the host system 12, for example by analyzing the time-varying changes in airflow, estimate the cause when airflow is outside the appropriate range, or estimate the period during which airflow is outside the appropriate range before it does.

[0068] The timing unit 1190 continuously measures the current time and generates time information representing the measured current time. The time information generated by the timing unit 1190 is used, for example, as time information stored in the "Time" column of a flow temporary storage table.

[0069] According to the smoke sensing system 1 described above, when a user observes the log data stored in the flow log table and determines that log data has been added to the flow log table at a high frequency without being used, the user can increase the set airflow change step value by operating button 116. As a result, the undesirable situation of storing useless log data in the flow log table can be mitigated, and the storage capacity of storage unit 1180 can be utilized efficiently.

[0070] Furthermore, according to the smoke sensing system 1 described above, when a user observes the log data stored in the flow log table and determines that the frequency of log data being appended to the flow log table is too low, the user can reduce the set airflow change step value by operating button 116. As a result, log data is then stored in the flow log table at an appropriate frequency, allowing the user to easily estimate the cause of the aforementioned flow anomalies based on the log data.

[0071] [Variation Example]

[0072] The above-described embodiments are specific examples of the present invention, and various modifications can be made within the scope of the technical concept of the present invention. Examples of their modifications are shown below. Furthermore, two or more of the modifications shown below can be appropriately combined.

[0073] (1) In the above embodiment, the operation receiving unit for accepting the user's operation on the smoke sensor 11 is a button 116, but the operation receiving unit of the smoke sensor 11 is not limited to a button. For example, a slider or switch, which are different types of physical operating components from buttons, can also be used as the operation receiving unit of the smoke sensor 11. Alternatively, a touch screen can also be used as the operation receiving unit of the smoke sensor 11. In this case, the operation receiving unit displays a virtual operating component on the screen and accepts the user's touch operation on the virtual operating component.

[0074] (2) In the above embodiment, the threshold changing unit 1187 changes the set airflow change step value according to the user's operation received by the operation acceptance unit exemplified by button 116. Alternatively, or based on this, the threshold changing unit 1187 may also change the set airflow change step value according to the data received by the communication unit 1189 (an example of a receiving unit) from the host system 12 (an example of an external device).

[0075] For example, when a user performs a specified operation on the host system 12, the host system 12 sends a request to the smoke sensor 11 to send a copy of the airflow change step value table. Based on the request, the smoke sensor 11 sends a copy of the airflow change step value table to the host system 12.

[0076] The host system 12 displays a table of airflow change step values ​​received from the smoke sensor 11. When the user changes the airflow change step value selected in the displayed airflow change step value table, the host system 12 generates an airflow change step value table with "○" stored in the "Selection" column of the record of the changed airflow change step value, and sends the airflow change step value table to the smoke sensor 11.

[0077] The smoke sensor 11 overwrites the airflow change step value table stored in the storage unit 1180 with the airflow change step value table received from the host system 12. As a result, the airflow change step value selected by the user who operated the host system 12 is reset in the smoke sensor 11.

[0078] In this variant, the user can change the airflow change step value used in the smoke sensor 11 without directly operating the smoke sensor 11.

[0079] (3) In the above embodiment, the threshold changing unit 1187 changes the set airflow change step value according to the user's operation. Alternatively, the threshold changing unit 1187 may also change the set airflow change step value based on the measured value of the flow meter 115 (an example of a flow measurement unit).

[0080] In this modified example, in storage cell 1180, instead of Figure 5 The structure shown stores the airflow change step value table. Figure 8 The illustrated structure has an airflow variation step value table. In this modified example, a "flow range" column has been added to each record in the airflow variation step value table.

[0081] For example, the threshold change unit 1187 determines which range the measured value in the "flow rate" column of the second row of the flow rate temporary storage table, i.e. the air flow rate last measured by the flow meter 115, falls into, as shown in the "flow rate range" column of the airflow change step value table, and updates the airflow change step value table so that "○" is stored in the "selection" column of the record corresponding to the determined range.

[0082] According to this variation, for example, when the airflow rate is lower, even a small change in flow rate results in a larger rate of change R, by storing high flow rate ranges in the "Flow Rate Range" column (where records with smaller values ​​are stored in the "Airflow Change Step Value" column) and low flow rate ranges in the "Flow Rate Range" column (where records with larger values ​​are stored in the "Airflow Change Step Value" column), an appropriate airflow change step value can be automatically selected and used based on the current flow rate without manual intervention. Therefore, this eliminates the need for the user to select the appropriate airflow change step value.

[0083] In this variation, instead of the airflow change step value table, the relationship between the flow range and the airflow change step value can be stored in the storage unit 1180. The threshold change unit 1187 calculates the airflow change step value corresponding to the current flow according to the relationship and sets the calculated airflow change step value.

[0084] (4) In the above embodiments, the selectable airflow change step value is a discrete value such as 10%, 20%, 30%, but the number of selectable airflow change step values ​​can be increased, and it is actually possible to set the airflow change step value selected from continuous values.

[0085] (5) In the above embodiment, the log data of airflow generated in the smoke sensor 11 is stored in the flow log table within the smoke sensor 11. Alternatively, or on this basis, the log data can be sent from the smoke sensor 11 to an external device (e.g., a host system 12) and stored in the external device.

[0086] (6) In the above embodiments, the hardware of the control unit 118 is a computer, but the control unit 118 may also be configured as a dedicated device with integrated circuits such as ASIC and FPGA.

[0087] Label Explanation

[0088] 1: Smoke sensing system; 10: Computer; 11: Smoke sensor; 12: Host system; 101: Processor; 102: Memory; 103: Input / output interface; 104: Communication interface; 110: Housing; 111: Light-emitting part; 112: Light-receiving part; 113: Fan; 114: Filter; 115: Flow meter; 116: Button; 117: Light-emitting part; 118: Control unit; 1101: Wall; 1102: Tube; 1103: Tube; 1180: Storage unit; 1181: Light-emitting indicator unit; 1182: Light intensity signal acquisition unit; 1183: Flow signal acquisition unit; 1184: Log generation unit; 1185: Flow anomaly judgment unit; 1186: Smoke judgment unit; 1187: Threshold change unit; 1188: Light-emitting indicator unit; 1189: Communication unit; 1190: Timing unit.

Claims

1. A smoke sensor that detects the generation of smoke in the external space by sensing particles contained in air flowing into a sensing area from the external space, wherein, The smoke sensor has the following features: Flow measurement unit, which measures the flow rate of air; A log generation unit generates log data representing the measured values ​​when the rate of change of the measured values ​​from the flow measurement unit reaches a threshold. as well as A threshold changing unit that changes the threshold based on input from an external source.

2. The smoke sensor according to claim 1, wherein, The smoke sensor has an operation acceptance unit that accepts user operations. The threshold changing unit changes the threshold based on the operation accepted by the operation acceptance unit as input from the external source.

3. The smoke sensor according to claim 1, wherein, The smoke sensor has a receiving unit that receives data from external devices. The threshold changing unit changes the threshold based on data received by the receiving unit as input from the external source.

4. A smoke sensor that detects the generation of smoke in the external space by sensing particles contained in air flowing into a sensing area from the external space, wherein, The smoke sensor has the following features: Flow measurement unit, which measures the flow rate of air; A log generation unit generates log data representing the measured values ​​when the rate of change of the measured values ​​from the flow measurement unit reaches a threshold. as well as The threshold changing unit changes the threshold. The threshold changing unit changes the threshold based on the measured value from the flow measurement unit.

5. The smoke sensor according to claim 4, wherein, The smaller the measured value of the flow measurement unit, the larger the threshold value is adjusted by the threshold adjustment unit.

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