Smoke detector

Abstract

The present invention provides a smoke sensor that can estimate the presence or absence of condensation without the need for a light-emitting means to detect condensation. The smoke sensor includes a control unit (118), which has a temperature signal acquisition means (1183) that estimates whether condensation is occurring on the object based on the following: the temperature of an object that is prone to condensation in the sensing area, which is the area where the smoke sensor detects smoke; the temperature of the air flowing into the sensing area, measured by a thermometer (1171); and the humidity of the air in the sensing area, measured by a hygrometer (116).

Description

[Technical Field]

[0001] This invention relates to a technology for sensing smoke. [Previous Technology]

[0002] A smoke detector (hereinafter referred to as "photoelectric smoke detector") is known to illuminate the sensing area with light from a light-emitting element and receive the scattered light scattered by particles in the air in the sensing area through a light-receiving element. Then, based on the intensity of the light received and measured by the light-receiving element, the particles contained in the air flowing into the sensing area from the external space are sensed, thereby sensing the occurrence of smoke in the external space.

[0003] When condensation occurs inside the photoelectric smoke sensor, light scattering due to condensation will occur in the sensing area. In some cases, this scattering may be mistaken for light scattering caused by smoke. Furthermore, condensation on the light-receiving element or the lens that guides the light to the light-receiving element may also be mistaken for dirt. Therefore, by determining whether condensation has occurred inside the photoelectric smoke sensor, the occurrence of such false positives can be reduced, and the accuracy of smoke detection and dirt detection can be improved.

[0004] Patent document 1, for example, discloses a technique for preventing false smoke detection caused by condensation. Patent document 1 proposes a technique in which a light-emitting element and a light-receiving element for detecting condensation are installed in a fire alarm device such as a photoelectric smoke sensor, and condensation within the fire alarm device is detected based on the light output of the light-receiving element. The light-emitting element for detecting condensation is used to detect the presence of condensation, and the light-receiving element is positioned to directly receive at least a portion of the light emitted from the light-emitting element for detecting condensation. [Prior Art Documents] [Patent Documents]

[0005] Patent Document 1: Japanese Patent Application Publication No. 2-18696 [Summary of the Invention]

[0006] [The problem the invention aims to solve]

[0007] In the case of the invention described in Patent Document 1, in addition to setting up a light-emitting element for smoke detection, it is also necessary to set up a light-emitting element for condensation detection, and the so-called disadvantage of high cost or large size of device will occur.

[0008] In view of the above, the present invention provides a smoke detector that can determine the presence or absence of condensation without requiring a light-emitting means for detecting condensation. [Means for Solving the Problem]

[0009] To solve the above-mentioned problems, the present invention proposes a smoke detector that senses the generation of smoke in the aforementioned external space by sensing particles contained in the air flowing into the sensing area from the external space. The smoke detector comprises: a light-emitting means for emitting light; a light-receiving means for receiving light; a temperature-measuring means for measuring temperature; a humidity-measuring means for measuring humidity; and a condensation estimation means for estimating the presence or absence of condensation in the aforementioned sensing area based on the measured values ​​of the aforementioned temperature-measuring means and the aforementioned humidity-measuring means. [Effects of the Invention]

[0010] According to the present invention, the presence or absence of condensation in the smoke detector can be determined without the need for a light-emitting means for detecting condensation.

Implementation Method

[0012] [Implementation Form]

[0013] The following describes a smoke detection system 1 according to one embodiment of the present invention. FIG1 is a diagram showing the configuration of the smoke detection system 1. The smoke detection system 1 includes a smoke sensor 11 and an upper system 12.

[0014] The smoke sensor 11 is a device that is disposed in the space of the monitored object where smoke occurs (hereinafter referred to as the "monitoring space"), and takes in the air in the monitoring space. If the air taken in contains smoke, it will detect the smoke, and if smoke is detected, it will send a smoke alarm to the higher system 12.

[0015] In Figure 1, although the number of smoke sensors 11 in the smoke detection system 1 is one, the number of smoke sensors 11 in the smoke detection system 1 varies depending on the number or width of the monitored space.

[0016] The high-level system 12 may also be any one of a monitoring terminal device, a smoke alarm panel, a central monitoring system, etc. The high-level system 12 and the smoke sensor 11 can communicate with each other through wired, wireless, or hybrid communication media and exchange data.

[0017] Since the higher-order system 12 is the same as the higher-order system of the prior art, its description is omitted.

[0018] Figure 2 is a schematic diagram showing the configuration of the smoke sensor 11. The smoke sensor 11 includes a housing 110, a light-emitting part 111, a light-receiving part 112, a lens 113, a fan 114, a filter 115, a hygrometer 116, a flow meter 117, and a control unit 118.

[0019] The housing 110 is a container that forms a space inside. The housing 110 has an air intake port P and an air exhaust port Q. The air intake port P is an opening that functions as an inlet for air to flow from the external space into the internal space, and the air exhaust port Q is an opening that functions as an outlet for air to flow from the internal space to the external space.

[0020] Furthermore, the housing 110 has a wall 1101, a pipe 1102 and a pipe 1103. The wall 1101 is used to form a sensing area S in the internal space as a region for sensing smoke. The pipe 1102 forms an air flow path from the air intake P to the sensing area S. The pipe 1103 forms an air flow path from the sensing area S to the exhaust port Q.

[0021] The light-emitting unit 111 (an example of a light-emitting means) has, for example, an LED, and emits light from the LED to the sensing area S. The light-receiving unit 112 (an example of a light-receiving means) is positioned in a position not facing the light-emitting unit 111, so that the light emitted from the light-emitting unit 111 does not directly enter the sensing area S, but is scattered light scattered by particles in the air within the sensing area S. The light-receiving unit 112 has, for example, a photodiode, and receives the light concentrated by the lens 113 from the scattered light within the sensing area S, and then outputs a light intensity signal indicating the intensity of the received light to the control unit 118.

[0022] The photodiode's output value changes with temperature even when receiving light of the same intensity. Therefore, the light-receiving unit 112 includes a thermometer 1121 (an example of a temperature measuring means, a first thermometer) for correcting the output value of the photodiode. The thermometer 1121 measures the temperature of the photodiode and outputs a temperature signal indicating the measured temperature to the control unit 118.

[0023] The fan 114 is disposed on the airflow path formed by the pipe 1102 and performs the task of causing the airflow from the external space toward the sensing area S by means of rotating blades.

[0024] The filter 115 is disposed 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.

[0025] A hygrometer 116 (an example of a humidity measurement method) is disposed within a sensing area S and measures the relative humidity within the sensing area S, and then outputs a humidity signal representing the measured relative humidity to a control unit 118. The hygrometer 116 is, for example, an electronic hygrometer.

[0026] The flow meter 117 is a sensor that measures the flow rate of air flowing into the sensing area S from the outside space by means of the operation of the fan 114, and outputs a flow signal indicating the measured flow rate to the control unit 118.

[0027] The flow meter 117 is, for example, a thermal flow meter based on the temperature difference measurement method, and has a thermometer 1171 (an example of a temperature measuring means, a second thermometer) for measuring the temperature of air flowing into the interior from outside the smoke sensor 11. Furthermore, the thermal flow meter has a heater and two temperature sensors disposed upstream and downstream of the airflow relative to the heater. In this case, the upstream temperature sensor performs the function of the thermometer 1171. The thermometer 1171 outputs a temperature signal indicating the measured temperature to the control unit 118. The thermometer 1171 is disposed upstream of the airflow path, even more so than the thermometer 112.

[0028] The control unit 118 is a device for controlling the operation of the smoke sensor 11. The hardware of the control unit 118 is, for example, a computer, and the control unit 118 is implemented by the computer performing processing according to the program used by the control unit 118.

[0029] Figure 3 is a diagram showing the configuration of the computer 10, which is used as the hardware of the control unit 118. The computer 10 includes: a processor 101 for performing various data processing; a memory 102 for storing various data; an input / output interface 103 for receiving and transmitting signals between the computer and components such as the light-emitting part 111 of the smoke sensor 11; and a communication interface 104 for sending and receiving data with external devices (in this case, the high-level system 12).

[0030] Figure 4 is a diagram showing the functional configuration of the control unit 118. That is, the control unit 118, which has the configuration shown in Figure 4, is implemented by the computer 10 performing processing according to the program used by the control unit 118. The functional configuration of the control unit 118 will be described below.

[0031] The memory means 1180 stores various data. The data stored in the memory means 1180 includes the following: (1) Smoke detection condition data indicating the conditions for determining the presence or absence of smoke based on the light intensity signal output from the light receiving unit 112; (2) Flow abnormality determination condition data indicating the conditions for determining the presence or absence of abnormal flow of air flowing from the outside into the smoke detector 11 based on the flow signal output from the flow meter 117; (3) Dew point temperature data indicating the correspondence between air temperature, relative humidity of the air, and the upper limit of the temperature of the object where condensation occurs in the air (dew point temperature).

[0032] The smoke detection condition data mentioned in (1) above may be, for example, a range of light intensity and a threshold value for the duration. That is, if the light intensity shown by the light intensity signal output by the light receiving unit 112 is within the range of light intensity shown by the smoke detection condition data, and is maintained at or above the threshold value for a period of time, it is determined that smoke exists in the air around the smoke detector 11.

[0033] The abnormal flow determination condition data mentioned in (2) above is, for example, a threshold value representing the range and duration of air flow. That is, if the air flow indicated by the flow signal output by the flow meter 117 is outside the range of the flow indicated by the abnormal flow determination condition data, and only remains above the threshold value for a period of time, it is determined that the air flow from the outside of the smoke sensor 11 into the interior is abnormal.

[0034] The dew point temperature data mentioned in (3) above is, for example, the data in tabular form shown in Figure 5. The rows of the table shown in Figure 5 correspond to the temperature of the air surrounding the object. The columns of the table shown in Figure 5 correspond to the relative humidity of the air surrounding the object where condensation occurs. Then, the value stored in each cell of the table shown in Figure 5 represents the dew point temperature, that is, the temperature of the object at which condensation begins to occur. For example, the value of 0.1 degrees Celsius stored in the cell of the row of 10 degrees Celsius and the column of 50% relative humidity in Figure 5 means that in air at 10 degrees Celsius and 50% relative humidity, condensation will occur on the object if there is an object with a temperature below 0.1 degrees Celsius.

[0035] Referring to FIG4, the functional configuration of the control unit 118 will continue to be explained. The light emission indicator 1181 indicates the light emission of the light emission unit 111. The light intensity signal acquisition means 1182 acquires the light intensity signal output from the light receiving unit 112.

[0036] Temperature signal acquisition means 1183 acquires the temperature signal output from thermometer 1121. Humidity signal acquisition means 1184 acquires the humidity signal output from hygrometer 116.

[0037] The flow signal acquisition means 1185 acquires the flow signal output from the flow meter 117. The temperature signal acquisition means 1186 acquires the temperature signal output from the thermometer 1171.

[0038] The smoke detection means 1187 determines whether the intensity of the light signal obtained by the light intensity signal acquisition means 1182 meets the conditions shown in the smoke detection condition data, thereby determining whether smoke exists in the air surrounding the smoke sensor 11. If smoke is determined to be present, the smoke detection means 1187 generates smoke occurrence notification data. The smoke occurrence notification data generated by the smoke detection means 1187 is sent to the higher-level system 12 via the communication means 1190.

[0039] The condensation estimation method 1188 is based on: the temperature signal obtained by the temperature signal obtained by the temperature signal obtained by the temperature signal obtained by the temperature signal obtained by the temperature signal obtained by the temperature signal obtained by the temperature signal obtained by the temperature signal obtained by the temperature signal obtained by the temperature signal obtained by the temperature signal obtained by the temperature signal obtained by the temperature signal obtained by the temperature signal obtained by the temperature signal obtained by the temperature signal obtained by the temperature signal obtained by the temperature signal obtained by the temperature signal obtained by the temperature signal obtained by the temperature signal obtained by the flow meter 1171, and the relationship between the relative humidity and the two types of temperatures shown in the dew point temperature data (Fig. 5), to estimate whether condensation is occurring in the lens 113.

[0040] The condensation estimation means 1188 takes the current temperature of the lens 113 as the temperature signal obtained by the temperature signal acquisition means 1183 from the thermometer 1121 of the light-receiving part 112. That is, in this embodiment, the lens 113 is in contact with the photodiode of the light-receiving part 112, and it is assumed that the temperature difference between the photodiode and the lens 113 is so small as to be negligible.

[0041] Furthermore, the condensation estimation means 1188 takes the temperature signal obtained by the temperature signal acquisition means 1186 from the temperature meter 1171 of the flow meter 117 as the current temperature of the air surrounding the lens 113. That is, in this embodiment, the time it takes for the air flowing into the smoke sensor 11 from the outside to the inside to move from the position of the flow meter 117 to the position of the lens 113 is assumed to be negligible compared to the time required for condensation to occur and disappear.

[0042] In the table showing dew point temperature data (Fig. 5), the dew point temperature represented by the value stored in the cell corresponding to the temperature signal obtained by the temperature signal acquisition means 1186 from the temperature meter 1171 of the flow meter 117 and the relative humidity signal obtained by the humidity signal acquisition means 1184 from the humidity meter 116 is set as the dew point temperature R. And when the current temperature shown by the temperature signal obtained by the temperature signal acquisition means 1183 from the temperature meter 1121 of the light receiving unit 112 is set as the lens temperature T, the condensation estimation means 1188 estimates as follows.

[0043] When the lens temperature T is below the dew point temperature R, it is presumed that condensation occurs on the lens 113. When the lens temperature T is higher than the dew point temperature R, it is presumed that no condensation occurs on the lens 113.

[0044] The condensation estimation means 1188 generates condensation occurrence notification data to indicate the occurrence of condensation when condensation is estimated to occur on the lens 113. The condensation occurrence notification data generated by the condensation estimation means 1188 is sent to the higher-level system 12 via the communication means 1190.

[0045] The flow rate abnormality determination means 1189 determines whether the air flow rate shown by the flow rate signal obtained by the flow rate signal acquisition means 1185 meets the conditions shown in the flow rate abnormality determination condition data, thereby determining whether the air flow rate flowing into the interior from the outside of the smoke detector 11 is abnormal.

[0046] The flow anomaly determination method 1189 generates flow anomaly notification data when it is determined that the flow rate of air flowing into the interior from the outside of the smoke sensor 11 is abnormal. The flow anomaly notification data generated by the flow anomaly determination method 1189 is sent to the high-level system 12 via the communication method 1190.

[0047] The communication means 1190 is used to send and receive various data with the higher-order system 12. Specifically, the communication means 1190 sends the smoke occurrence notification data generated by the smoke determination means 1187, the condensation occurrence notification data generated by the condensation estimation means 1188, and the flow anomaly notification data generated by the flow anomaly determination means 1189 to the higher-order system 12, as described above.

[0048] Based on the smoke detection system 1 described above, it can be determined whether condensation has occurred on the lens 113 of the smoke sensor 11. Therefore, when the smoke sensor 11 notifies the user of the occurrence of smoke by sending smoke occurrence notification data, if the occurrence of condensation is also notified by sending condensation occurrence notification data, the user can consider the possibility that the smoke occurrence notification is a false alarm and take appropriate action.

[0049] [Variations] The above-described embodiments are specific examples of the present invention, and various variations can be made within the scope of the technical concept of the present invention. Examples of such variations are shown below. Furthermore, two or more variations shown below can also be appropriately combined.

[0050] (1) In the above embodiment, the hygrometer 116 measures relative humidity. Alternatively, the hygrometer 116 can also measure absolute humidity. Relative humidity is calculated from absolute humidity and temperature according to a known formula. Thus, for example, the condensation estimation means 1188 can also calculate the relative humidity based on the absolute humidity measured by the hygrometer 116 and the temperature measured by the thermometer 1171, and estimate whether condensation occurs in the lens 113.

[0051] (2) In the above embodiment, the condensation estimation means 1188 estimates the presence or absence of condensation based on the measured value of thermometer 1121 and the measured value of thermometer 1171, which is located upstream of the air flow path. The two temperatures used by the condensation estimation means 1188 to estimate the presence or absence of condensation may not be temperatures measured by temperature measuring means located in different positions on the upstream and downstream sides of the air flow path.

[0052] Figure 6 is a schematic diagram showing the configuration of the smoke sensor 11 in this variation. The smoke sensor 11 in this variation differs from the smoke sensor 11 in the embodiment described above in that it includes a thermometer 119.

[0053] The thermometer 119 is disposed within the sensing area S and measures the temperature of the air within the sensing area S. The position of the thermometer 119 is compared with the thermometer 1121 on the light receiving part 112, and may not necessarily be upstream of the air flow path.

[0054] Figure 7 is a diagram showing the functional configuration of the control unit 118 in this variation. The control unit 118 in this variation differs from the control unit 118 in the embodiment described above in that the temperature signal acquisition means 1186 acquires the temperature signal from the thermometer 119 instead of the thermometer 1171.

[0055] In this variation, the condensation estimation means 1188 is to use the temperature measured by the thermometer 119 instead of the temperature measured by the thermometer 1171 to estimate the presence or absence of condensation.

[0056] Furthermore, in the smoke sensor 11 with the configuration shown in FIG6, the control unit 118 may pre-memorize temperature data representing the temperature measured by the thermometer 119, and replace the temperature measured by the thermometer 1121, and use the temperature change over time shown by the measured value measured by the thermometer 119 to determine whether condensation exists.

[0057] Figure 8 is a diagram showing the functional configuration of the control unit 118 in this variation example. The control unit 118 in this variation example is equipped with a timing means 1191. The timing means 1191 continuously measures the current time, for example, based on a clock signal generated by a clock provided by the processor 101.

[0058] The memory means 1180 stores the temperature shown in the temperature signal and the data corresponding to the current time measured by the timing means 1191 as temperature log data each time the temperature signal acquisition means 1186 acquires a temperature signal from the thermometer 119. The temperature log data represents the change of air temperature in the sensing area S measured by the thermometer 119 over time.

[0059] The temperature of lens 113 is determined by tracking changes in the ambient air temperature around lens 113 based on the response speed calculated using a known formula according to the heat capacity of lens 113. Therefore, in this variation example, the condensation estimation means 1188 calculates the temperature of lens 113 based on temperature log data and uses the calculated temperature of lens 113 to estimate whether condensation occurs in lens 113.

[0060] Furthermore, in this variation, the temperature measured by the thermometer 1171 of the flow meter 117 can be used instead of the temperature measured by the thermometer 119.

[0061] Furthermore, the thermometer 119 can also be integrated with the hygrometer 116.

[0062] (3) In the above embodiment, the condensation estimation means 1188 estimates the presence or absence of condensation based on the measured values ​​of thermometer 1121 and thermometer 1171. Alternatively, the condensation estimation means 1188 may also estimate the presence or absence of condensation based on the measured values ​​of thermometer 1121 and the measured values ​​of the thermometers possessed by the computer 10 constituting the control unit 118.

[0063] Figure 9 is a diagram showing the configuration of the computer 10 in this variation. In this variation, the computer 10 is equipped with a thermometer 105 for measuring the ambient temperature.

[0064] The temperature measured by thermometer 105 represents the temperature determined by the heat generated by computer 10 and the ambient air temperature after a predetermined time has elapsed since computer 10 started operating. Since the processing load of computer 10 does not change significantly, the heat generated by computer 10 can be considered constant. Furthermore, the ambient air temperature of computer 10 and the air temperature flowing into sensing area S from the external space are the same, or there is a certain relationship between these temperatures.

[0065] Thus, after the computer 10 starts operating, there is a certain relationship between the measured value of the thermometer 105 after a predetermined time period and the air temperature flowing into the sensing area S from the external space. Therefore, in this variation, the memory means 180 stores in advance a calculation formula or a correspondence table for estimating the air temperature flowing into the sensing area S from the measured value of the thermometer 105.

[0066] In this variation, the temperature signal acquisition means 1186 acquires the temperature signal output from the thermometer 105. The condensation estimation means 1188 estimates the air temperature flowing into the sensing area S from the external space based on the temperature signal obtained by the temperature signal acquisition means 1186 from the thermometer 105, according to the calculation formula or correspondence table stored in the memory means 1180. Then, the condensation estimation means 1188 estimates the presence or absence of condensation based on the temperature estimated from the temperature measured by the thermometer 105 and the temperature measured by the thermometer 1121.

[0067] Furthermore, when the thermometer 1171 (or, the thermometer 119 in the above variation (2)) is operating normally, the measurement value of the thermometer is used to estimate condensation. In the event that the thermometer 1171 (or, the thermometer 119 in the above variation (2)) malfunctions, the measurement value of the thermometer 105 can be used instead of the measurement value of the thermometer to estimate condensation.

[0068] (4) The smoke detector 11 has a second light-emitting part that is different from the light-emitting part 111 (first light-emitting part) for sensing dirt in the sensing area S as a light-emitting means. The condensation estimation means 1188 can estimate the presence or absence of condensation based on the measured values ​​of thermometers 1121 and 1171 and the measured values ​​of hygrometer 116, as well as the measured values ​​of the light-receiving part 112 when the second light-emitting part is emitting light.

[0069] FIG10 is a schematic diagram showing the configuration of the smoke sensor 11 of this variation. The smoke sensor 11 of this variation differs from the smoke sensor 11 of the above embodiment in that it has a light-emitting part 120 (an example of a second light-emitting part).

[0070] The light-emitting part 120 is a light-emitting part used to sense the dirtiness of the lens 113. For example, it is disposed at a position closer to the lens 113 than the light-emitting part 111 after the air flow path in the sensing area S has deviated. Therefore, the intensity of the light irradiated from the light-emitting part 120 and received by the light-receiving part 112 is substantially not affected by the particles in the air flowing from the air intake port P toward the exhaust port Q, but mainly varies by the degree of dirtiness of the lens 113.

[0071] Figure 11 is a diagram showing the functional configuration of the control unit 118 in this variation example. Compared with the control unit 118 in the above embodiment, the control unit 118 in this variation example is different in that it includes: a light emission indicator 1192, which indicates the light emission of the light emission unit 120; and a dirt estimation means 1193, which estimates the degree of dirtiness of the lens 113 based on the light intensity signal output by the light receiving unit 112 when the light emission unit 120 is emitting light.

[0072] In this variation, the memory means 1180 stores data showing the correspondence between the light intensity signal output by the light receiving part 112 when the light emitting part 120 is emitting light and the degree of dirtiness of the lens 113. The dirtiness estimation means 1193 uses this data to estimate the degree of dirtiness of the lens 113.

[0073] The smoke detection means 1187 determines the presence or absence of smoke by adjusting the light intensity signal output by the light receiving part 112 when the light-emitting part 111 is emitting light, or the range of light intensity shown by the smoke detection condition data, based on the degree of dirtiness of the lens 113 estimated by the dirtiness estimation means 1193.

[0074] The condensation estimation means 1188, based on dew point temperature data (Fig. 5), estimates that condensation is occurring based on the temperatures measured by thermometers 1121 and 1171, and the temperature measured by thermometer 116, and then instructs the light-emitting means 1192 to illuminate the light-emitting part 120. Then, the condensation estimation means 1188 compares the light intensity signal output from the light-receiving part 112 and acquired by the light intensity signal acquisition means 1182 when the light-emitting part 120 is emitting light with the light intensity at normal times when condensation has not occurred.

[0075] The condensation estimation method 1188 determines that condensation is occurring and generates condensation estimation data when the light intensity signal output from the light receiving unit 112 during the emission of light from the light emitting unit 120 is above a threshold value different from the normal light intensity.

[0076] According to this variation example, although there are errors in the measured values ​​of thermometer 1121, thermometer 1171, or hygrometer 116, and the measured values ​​of them show the occurrence of condensation according to the dew point temperature data, the false reporting of the occurrence of condensation can be prevented when condensation does not actually occur.

[0077] (5) In the above embodiment, the temperature of the lens 113 is measured by the thermometer 1121 provided on the light-receiving part 112. Alternatively, the temperature of the lens 113 can be measured by a different thermometer than the thermometer 1121. According to this variation, even if the temperature of the lens 113 cannot be accurately measured by the thermometer 1121 provided on the light-receiving part 112 due to reasons such as the distance between the light-receiving part 112 and the lens 113, the condensation estimation means 1188 can still estimate whether condensation has occurred.

[0078] (6) When condensation is occurring, it is easier to generate false smoke detection than when condensation is not occurring. Therefore, when condensation is presumed to be occurring by condensation presumption means 1188, smoke determination means 1187 can determine the presence or absence of smoke under stricter conditions than usual (when condensation is presumed not to be occurring).

[0079] In this variation, for example, the memory means 1180 stores smoke detection condition data used normally and when condensation occurs. As described above, the smoke detection condition data, for example, represents the range of light intensity and the threshold value of the duration, which is used as a condition to determine the presence or absence of smoke. The range of light intensity shown in the smoke detection condition data used when condensation occurs is narrower than the range of light intensity shown in the smoke detection condition data used normally. Furthermore, the duration shown in the smoke detection condition data used when condensation occurs is longer than the duration shown in the smoke detection condition data used normally.

[0080] During the period when condensation is presumed not to have occurred by the condensation estimation means 1188, the smoke determination means 1187 uses smoke detection condition data normally used to determine the presence or absence of smoke. On the other hand, during the period when condensation is presumed to be occurring by the condensation estimation means 1188, the smoke determination means 1187 uses smoke detection condition data used when condensation occurs to determine the presence or absence of smoke.

[0081] According to this variation, since the presence or absence of smoke is determined under more stringent conditions during the period when condensation is presumed to be occurring, the occurrence of false alarms of smoke generation caused by condensation can be reduced.

[0082] (7) In the above embodiment, the presence or absence of condensation in the lens 113 is estimated. The lens 113 is one example of the object on which the smoke sensor 11 estimates the presence or absence of condensation. Any structure within the sensing area S, regardless of its type, can be used as the object on which the presence or absence of condensation is estimated. For example, if the smoke sensor 11 is equipped with a lens that directs the light emitted by the light-emitting part 111 to a predetermined range, the presence or absence of condensation in that lens can also be estimated. Furthermore, the presence or absence of condensation in the wall 1101 forming the sensing area S can also be estimated.

[0083] (8) In the above embodiment, the condensation estimation means 1188 uses dew point temperature data (Fig. 5) to estimate whether condensation occurs. Alternatively, the condensation estimation means 1188 can also calculate the dew point temperature according to the formula for calculating the dew point temperature with the temperature of the air around the object and the relative humidity of the air as variables, and compare the calculated dew point temperature with the measured value of the thermometer 1121 to estimate whether condensation occurs.

[0084] (9) In the above embodiment, although it is assumed that the hardware of the control unit 118 is a computer, the control unit 118 may also be configured as a dedicated device with integrated circuits such as ASIC (Application Specific Integrated Circuit) and FPGA (Field Programmable Gate Array). [Simplified Explanation of the Diagram]

[0011] [Figure 1] is a diagram showing the configuration of a smoke detection system according to an embodiment. [Figure 2] is a diagram schematically showing the configuration of a smoke sensor according to an embodiment. [Figure 3] is a diagram showing the configuration of a computer, which is used as the hardware of a control unit according to an embodiment. [Figure 4] is a diagram showing the functional configuration of a control unit according to an embodiment. [Figure 5] is a diagram showing the configuration of dew point temperature data according to an embodiment. [Figure 6] is a diagram schematically showing the configuration of a smoke sensor according to a variation. [Figure 7] is a diagram showing the functional configuration of a control unit according to a variation. [Figure 8] is a diagram showing the functional configuration of a control unit according to a variation. [Figure 9] is a diagram showing the configuration of a computer, which is used as the hardware of a control unit according to a variation. [Figure 10] is a diagram schematically showing the configuration of a smoke sensor according to a variation. [Figure 11] is a diagram showing the functional configuration of a control unit according to a variation.

Claims

1. A smoke detector that senses the generation of smoke in the external space by sensing particles contained in air flowing into a sensing area from the external space, characterized by comprising: a light-emitting means for emitting light; a light-receiving means for receiving light; a first temperature measuring means for measuring temperature; a second temperature measuring means disposed upstream of the airflow path closer to the first temperature measuring means; a humidity measuring means for measuring humidity; and a condensation estimation means that specifies a dew point temperature based on the measured value of the second temperature measuring means and the measured value of the humidity measuring means, and estimates the presence or absence of condensation in the sensing area based on a comparison result between the specified dew point temperature and the measured value of the first temperature measuring means.

2. The smoke detector as described in claim 1, wherein, The aforementioned method for estimating condensation is based on the measured values ​​obtained by the aforementioned temperature measurement method and the temperature changes over time shown therein, as well as the measured values ​​obtained by the aforementioned humidity measurement method, to estimate the presence or absence of condensation.

3. The smoke sensor as described in claim 1 or 2, wherein, The aforementioned light-emitting means comprises: a first light-emitting part for sensing smoke; and a second light-emitting part for sensing dirt in the aforementioned sensing area; the aforementioned condensation estimation means is based on: the measurement value of the aforementioned light-receiving means when the aforementioned second light-emitting part is emitting light, the measurement value of the aforementioned temperature measurement means, and the measurement value of the aforementioned humidity measurement means, to estimate the presence or absence of the aforementioned condensation.

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