Smoke sensor

Abstract

The present invention provides a smoke detector that can estimate the presence or absence of condensation without the need for a light-emitting means for detecting condensation. A temperature signal acquisition means 1183 included in a control unit 118 provided for the smoke detector estimates whether condensation has occurred on an object on the basis of a measured value of a thermometer 1121, a measured value of a thermometer 1171, and a measured value of a hygrometer 116. The thermometer 1121 measures a temperature of the object susceptible to condensation in a detection region where the smoke detector detects smoke, the thermometer 1171 measures a temperature of air flowing into the detection region, and the hygrometer 116 measures a humidity of air in the detection region.

Description

Technical Field

[0001] The present invention relates to a technique for detecting smoke.

Background Art

[0002] There is known a smoke detector (hereinafter referred to as a "photoelectric smoke detector") that irradiates light from a light emitting element to a detection area, receives scattered light scattered by particles in the air in the detection area by a light receiving element, and detects particles contained in the air flowing from the external space into the detection area based on the intensity of the light received and measured by the light receiving element, thereby detecting the occurrence of smoke in the external space.

[0003] When dew condensation occurs inside a photoelectric smoke detector, light scattering by dew may occur in the detection area, and it may be misrecognized as light scattering due to the occurrence of smoke. In addition, there may be cases of misrecognition as dirt due to dew condensation on the light receiving element or a lens that guides light to the light receiving element. Therefore, if it is possible to determine whether dew condensation has occurred inside the photoelectric smoke detector, the occurrence of such misrecognition can be reduced, and the accuracy of smoke detection and dirt detection can be improved.

[0004] As a patent document that discloses a technique for preventing false detection of smoke due to dew condensation, for example, there is Patent Document 1. In Patent Document 1, a fire alarm device such as a photoelectric smoke detector is provided with a dew condensation detection light emitting element for detecting the presence of dew condensation and a light receiving element arranged at a position where at least a part of the light emitted from the dew condensation detection light emitting element can be directly received, and a technique for detecting dew condensation inside the fire alarm device based on the light receiving output of the light receiving element has been proposed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the case of the invention described in Patent Document 1, it is necessary to provide a light-emitting element for detecting condensation in addition to the light-emitting element for detecting smoke, which results in disadvantages such as high cost and a larger device.

[0007] In view of the above circumstances, the present invention provides a smoke detector capable of estimating the presence or absence of condensation without requiring a light-emitting means for condensation detection. [Means for solving the problem]

[0008] To solve the above problems, the present invention proposes a smoke detector that detects the generation of smoke in an external space by sensing particles contained in the air flowing into a sensing area from an external space, and 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-estimating means for estimating the presence or absence of condensation in the sensing area based on the measured values ​​of the temperature-measuring means and the humidity-measuring means. [Effects of the Invention]

[0009] According to the present invention, the presence or absence of condensation inside a smoke detector can be estimated without requiring a light-emitting means for condensation detection. [Brief explanation of the drawing]

[0010] [Figure 1] A diagram showing the configuration of a smoke detection system according to one embodiment. [Figure 2] A schematic diagram showing the configuration of a smoke detector according to one embodiment. [Figure 3] A diagram showing the configuration of a computer used as hardware for a control unit according to one embodiment. [Figure 4] A diagram showing the functional configuration of a control unit according to one embodiment. [Figure 5] A diagram showing the configuration of dew point temperature data according to one embodiment. [Figure 6] A schematic diagram showing the configuration of a smoke detector according to one modified example. [Figure 7]A diagram showing the functional configuration of a control unit according to a modified example. [Figure 8] A diagram showing the functional configuration of a control unit according to a modified example. [Figure 9] A diagram showing the configuration of a computer adopted as hardware of a control unit according to a modified example. [Figure 10] A diagram schematically showing the configuration of a smoke detector according to a modified example. [Figure 11] A diagram showing the functional configuration of a control unit according to a modified example.

[0011] [Embodiment] The smoke detection system 1 according to an embodiment of the present invention will be described below. FIG. 1 is a diagram showing the configuration of the smoke detection system 1. The smoke detection system 1 includes a smoke detector 11 and an upper system 12.

[0012] The smoke detector 11 is arranged in a space to be monitored for smoke generation (hereinafter referred to as "monitoring space"), takes in the air in the monitoring space, senses the smoke if the taken-in air contains smoke, and when the smoke is sensed, transmits an alarm of smoke generation to the upper system 12.

[0013] In FIG. 1, the number of smoke detectors 11 included in the smoke detection system 1 is one, but the number of smoke detectors 11 included in the smoke detection system 1 varies according to the number and size of the monitoring spaces.

[0014] The upper system 12 may be any of a monitoring terminal device, a smoke alarm panel, a central monitoring system, etc. The upper system 12 and the smoke detector 11 are communicatively connected via a wired, wireless, or a mixed communication medium thereof, and can communicate with each other.

[0015] Since the upper system 12 is the same as the upper system according to the prior art, the description thereof is omitted.

[0016] FIG. 2 is a diagram schematically showing the configuration of the smoke detector 11. The smoke detector 11 includes a housing 110, a light emitting unit 111, a light receiving unit 112, a lens 113, a fan 114, a filter 115, a hygrometer 116, a flow meter 117, and a control unit 118.

[0017] The housing 110 is a container that forms a space inside. The housing 110 has an intake port P which is an opening that functions as an inlet for air to flow from the external space into the internal space, and an exhaust port Q which is an opening that functions as an outlet for air to flow out from the internal space to the external space.

[0018] Also, the housing 110 has a wall 1101 that forms a sensing area S which is an area for sensing smoke inside the internal space, a pipe 1102 that forms an air flow path from the intake port P to the sensing area S, and a pipe 1103 that forms an air flow path from the sensing area S to the exhaust port Q.

[0019] 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 arranged at a position not facing the light emitting unit 111 such that the scattered light scattered by the particles in the air in the sensing area S and not the light directly emitted from the light emitting unit 111 is incident thereon. The light receiving unit 112 has, for example, a photodiode, receives the light collected by the lens 113 among the scattered light in the sensing area S, and outputs a light intensity signal indicating the intensity of the received light to the control unit 118.

[0020] The output value of a photodiode changes depending on temperature even when receiving light of the same intensity. Therefore, the light receiving unit 112 has 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.

[0021] The fan 114 is positioned on the airflow path formed by the pipe 1102 and plays a role in generating an airflow from the external space toward the sensing area S through its rotating blades.

[0022] The filter 115 is positioned on the airflow path formed by the pipe 1102 and captures dust contained in the air moving from the outside space toward the sensing area S, thereby preventing dust from entering the sensing area S.

[0023] A hygrometer 116 (an example of a humidity measuring means) is placed within the sensing area S, measures the relative humidity within the sensing area S, and outputs a humidity signal indicating the measured relative humidity to the control unit 118. The hygrometer 116 is, for example, an electric hygrometer.

[0024] The flow meter 117 is a sensor that measures the flow rate of air flowing from the outside space into the sensing area S due to the operation of the fan 114, and outputs a flow signal indicating the measured flow rate to the control unit 118.

[0025] The flow meter 117 is a thermal flow meter that follows, for example, a temperature difference measurement method, and has a thermometer 1171 (temperature measuring means, an example of a second thermometer) that measures the temperature of the air flowing from the outside to the inside of the smoke detector 11. The thermal flow meter has a heater and two temperature sensors positioned upstream and downstream of the heater in the airflow. In this case, the upstream temperature sensor acts as the thermometer 1171. The thermometer 1171 outputs a temperature signal indicating the measured temperature to the control unit 118. The thermometer 1171 is positioned upstream of the thermometer 1121 in the airflow path.

[0026] The control unit 118 is a device that controls the operation of the smoke detector 11, etc. The hardware of the control unit 118 is, for example, a computer, and the control unit 118 is realized when the computer performs processing according to a program for the control unit 118.

[0027] Figure 3 shows the configuration of the computer 10 used as the hardware for the control unit 118. The computer 10 includes a processor 101 for processing various data, a memory 102 for storing various data, an input / output interface 103 for exchanging signals with components such as the light-emitting unit 111 of the smoke detector 11, and a communication interface 104 for sending and receiving data with an external device (in this case, a higher-level system 12).

[0028] Figure 4 shows the functional configuration of the control unit 118. That is, the control unit 118, equipped with the components shown in Figure 4, is realized when the computer 10 performs processing according to the program for the control unit 118. The functional components of the control unit 118 are described below.

[0029] The storage means 1180 stores various types of data. The data stored by the storage 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 rate abnormality determination condition data indicating the conditions for determining whether or not there is an abnormality in the flow rate of air flowing from the outside to the inside of the smoke detector 11 based on the flow rate signal output from the flow meter 117. (3) Dew point temperature data showing the relationship between air temperature, relative humidity of the air, and the upper limit of the temperature of an object in which condensation occurs (dew point temperature).

[0030] The smoke detection condition data in (1) above indicates, for example, a range of light intensity and a threshold for duration. That is, if the light intensity indicated by the light intensity signal output by the light receiving unit 112 is maintained within the range of light intensity indicated by the smoke detection condition data for a time greater than or equal to the threshold, it is determined that smoke is present in the air around the smoke detector 11.

[0031] The flow rate abnormality determination condition data in (2) above indicates, for example, the range and duration threshold of the air flow rate. That is, if the air flow rate indicated by the flow rate signal output by the flow meter 117 remains outside the flow rate range indicated by the flow rate abnormality determination condition data for a period of time greater than the threshold, it is determined that the air flow rate flowing from outside to inside the smoke detector 11 is abnormal.

[0032] The dew point temperature data in (3) above is, for example, tabular data as shown in Figure 5. The rows in the table shown in Figure 5 correspond to the temperature of the air around the object. The columns in the table shown in Figure 5 correspond to the relative humidity of the air around the object at which condensation occurs. The numerical values ​​stored in each cell of the table shown in Figure 5 represent the dew point temperature, that is, the temperature at which condensation begins to occur on the object. For example, the value of 0.1 degrees Celsius stored in the cell in the row for 10 degrees Celsius and the column for 50% relative humidity in Figure 5 means that if there is an object at a temperature of 0.1 degrees Celsius or lower in air at 10 degrees Celsius and 50% relative humidity, condensation will occur on that object.

[0033] Referring to Figure 4, the explanation of the functional configuration of the control unit 118 continues. The light emission instruction means 1181 instructs the light emission unit 111 to emit light. The light intensity signal acquisition means 1182 acquires the light intensity signal output from the light receiving unit 112.

[0034] The temperature signal acquisition means 1183 acquires the temperature signal output from the thermometer 1121. The humidity signal acquisition means 1184 acquires the humidity signal output from the hygrometer 116.

[0035] The flow rate signal acquisition means 1185 acquires the flow rate signal output from the flow meter 117. The temperature signal acquisition means 1186 acquires the temperature signal output from the thermometer 1171.

[0036] The smoke detection means 1187 determines whether smoke is present in the air around the smoke detector 11 by determining whether the light intensity indicated by the light intensity signal acquired by the light intensity signal acquisition means 1182 satisfies the conditions indicated by the smoke detection condition data. If the smoke detection means 1187 determines that smoke is present, it generates smoke generation notification data to notify of the occurrence of smoke. The smoke generation notification data generated by the smoke detection means 1187 is transmitted to the higher-level system 12 by the communication means 1190.

[0037] The condensation estimation means 1188 estimates whether or not condensation has occurred on the lens 113 based on the temperature indicated by the temperature signal acquired by the temperature signal acquisition means 1183 from the thermometer 1121 of the light receiving unit 112, the relative humidity indicated by the humidity signal acquired by the humidity signal acquisition means 1184 from the hygrometer 116, the temperature indicated by the temperature signal acquired by the temperature signal acquisition means 1186 from the thermometer 1171 of the flow meter 117, and the relationship between the relative humidity and the two types of temperature shown in the dew point temperature data (Figure 5).

[0038] The condensation estimation means 1188 considers the current temperature indicated by the temperature signal acquired by the temperature signal acquisition means 1183 from the thermometer 1121 of the light receiving unit 112 as the current temperature of the lens 113. In other words, in this embodiment, the lens 113 is in contact with the photodiode of the light receiving unit 112, and the temperature difference between the photodiode and the lens 113 is assumed to be negligibly small.

[0039] Furthermore, the condensation estimation means 1188 considers the temperature indicated by the temperature signal acquired by the temperature signal acquisition means 1186 from the thermometer 1171 of the flow meter 117 as the current temperature of the air surrounding the lens 113. In other words, in this embodiment, the time it takes for air flowing from the outside to the inside of the smoke detector 11 to travel from the position of the flow meter 117 to the position of the lens 113 is considered to be negligibly small compared to the time required for condensation to occur and dissipate.

[0040] In the table shown in the dew point temperature data (Figure 5), if the dew point temperature R is the value stored in the cell where the row corresponding to the temperature indicated by the temperature signal acquired by the temperature signal acquisition means 1186 from the thermometer 1171 of the flow meter 117 intersects with the column corresponding to the relative humidity indicated by the humidity signal acquired by the humidity signal acquisition means 1184 from the hygrometer 116, and the lens temperature T is the current temperature indicated by the temperature signal acquired by the temperature signal acquisition means 1183 from the thermometer 1121 of the light receiving unit 112, then the condensation estimation means 1188 estimates as follows.

[0041] If the lens temperature T is below the dew point temperature R, it is presumed that condensation has occurred on the lens 113. If the lens temperature T is higher than the dew point temperature R, it is presumed that no condensation has occurred on the lens 113.

[0042] If the condensation estimation means 1188 estimates that condensation has occurred on the lens 113, it generates condensation occurrence notification data to notify the system of condensation occurrence. The condensation occurrence notification data generated by the condensation estimation means 1188 is transmitted to the higher-level system 12 via the communication means 1190.

[0043] The flow rate abnormality determination means 1189 determines whether the flow rate of air flowing from the outside to the inside of the smoke detector 11 is abnormal by determining whether the flow rate of air indicated by the flow rate signal acquired by the flow rate signal acquisition means 1185 satisfies the conditions indicated by the flow rate abnormality determination condition data.

[0044] The flow rate abnormality determination means 1189 generates flow rate abnormality notification data to notify of the flow rate abnormality if it estimates that the flow rate of air flowing from the outside to the inside of the smoke detector 11 is abnormal. The flow rate abnormality notification data generated by the flow rate abnormality determination means 1189 is transmitted to the higher-level system 12 by the communication means 1190.

[0045] The communication means 1190 transmits and receives various types of data with the higher-level system 12. Specifically, as described above, the communication means 1190 transmits smoke generation notification data generated by the smoke detection means 1187, condensation generation notification data generated by the condensation estimation means 1188, and flow rate abnormality notification data generated by the flow rate abnormality detection means 1189 to the higher-level system 12.

[0046] According to the smoke detection system 1 described above, it is possible to determine whether or not condensation has occurred on the lens 113 of the smoke detector 11. Therefore, when the smoke detector 11 notifies of the occurrence of smoke by sending smoke occurrence notification data, if it also notifies of the occurrence of condensation by sending condensation occurrence notification data, the higher-level system 12, or the user of the higher-level system 12, can consider the possibility that the smoke occurrence notification is a false alarm and take appropriate action.

[0047] [Differentiation] The embodiments described above are specific examples of the present invention and can be modified in various ways within the scope of the technical idea of ​​the present invention. Examples of such modifications are shown below. Two or more of the following modifications may be combined as appropriate.

[0048] (1) In the embodiment described above, the hygrometer 116 measures relative humidity. Alternatively, the hygrometer 116 may measure absolute humidity. Relative humidity is calculated from absolute humidity and temperature according to a known predetermined calculation formula. Therefore, for example, the condensation estimation means 1188 may calculate relative humidity based on the absolute humidity measured by the hygrometer 116 and the temperature measured by the thermometer 1171, and estimate whether or not condensation occurs on the lens 113.

[0049] (2) In the embodiment described above, the condensation estimation means 1188 estimates the presence or absence of condensation based on the measurement value of the thermometer 1121 and the measurement value of the thermometer 1171 which is located upstream of the thermometer 1121 in the airflow path. The two temperatures used by the condensation estimation means 1188 to estimate the presence or absence of condensation do not have to be temperatures measured by different temperature measuring means that are located upstream and downstream of the airflow path.

[0050] Figure 6 is a schematic diagram showing the configuration of the smoke detector 11 according to this modified example. The smoke detector 11 according to this modified example differs from the smoke detector 11 according to the embodiment described above in that it is equipped with a thermometer 119.

[0051] The thermometer 119 is placed within the sensing area S and measures the temperature of the air within the sensing area S. The position of the thermometer 119 does not necessarily have to be upstream of the airflow path, compared to the thermometer 1121 located in the light-receiving unit 112.

[0052] Figure 7 shows the functional configuration of the control unit 118 according to this modified example. The control unit 118 according to this modified example differs from the control unit 118 according to the embodiment described above in that the temperature signal acquisition means 1186 acquires the temperature signal from a thermometer 119 instead of a thermometer 1171.

[0053] In this modified example, the condensation estimation means 1188 uses the temperature measured by thermometer 119 instead of the temperature measured by thermometer 1171 to estimate whether or not condensation is present.

[0054] Furthermore, in a smoke detector 11 having the configuration shown in Figure 6, the control unit 118 may store temperature data indicating the temperature measured by the thermometer 119, and instead of the temperature measured by the thermometer 1121, the presence or absence of condensation may be determined using the change in temperature over time indicated by the measurement value of the thermometer 119.

[0055] Figure 8 shows the functional configuration of a control unit 118 according to such a modified example. This modified control unit 118 includes a timing means 1191. The timing means 1191 continuously measures the current time based on a clock signal generated by a clock provided by the processor 101, for example.

[0056] The storage means 1180 stores, as temperature log data, data that associates the temperature indicated by the temperature signal with the current time measured by the timing means 1191, each time the temperature signal acquisition means 1186 acquires a temperature signal from the thermometer 119. The temperature log data shows the change in air temperature within the sensing area S measured by the thermometer 119 over time.

[0057] The temperature of lens 113 follows changes in the temperature of the air surrounding lens 113 at a response speed calculated according to a known calculation formula based on the heat capacity of lens 113. In this modified 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 or not condensation occurs on lens 113.

[0058] In this modified example, the temperature measured by the thermometer 1171 of the flow meter 117 may be used instead of the temperature measured by the thermometer 119.

[0059] Alternatively, the thermometer 119 may be integrated with the hygrometer 116.

[0060] (3) In the embodiment described above, the condensation estimation means 1188 estimates the presence or absence of condensation based on the measurement value of the thermometer 1121 and the measurement value of the thermometer 1171. Alternatively, the condensation estimation means 1188 may estimate the presence or absence of condensation based on the measurement value of the thermometer 1121 and the measurement value of the thermometer provided in the computer 10 that constitutes the control unit 118.

[0061] Figure 9 shows the configuration of the computer 10 according to this modified example. In this modified example, the computer 10 is equipped with a thermometer 105 for measuring the ambient temperature.

[0062] The temperature measured by the thermometer 105 rises until a predetermined time has elapsed after the computer 10 starts operating, and after the predetermined time has elapsed, it shows a temperature determined by the amount of heat generated by the computer 10 and the temperature of the air surrounding the computer 10. Since the processing load of the computer 10 does not fluctuate significantly, the amount of heat generated by the computer 10 can be considered constant. In addition, the temperature of the air surrounding the computer 10 and the temperature of the air flowing from the external space into the sensing area S are either the same or there is a constant relationship between their temperatures.

[0063] Therefore, there is a certain relationship between the measurement of the thermometer 105 after a predetermined time has elapsed since the computer 10 started operating, and the temperature of the air flowing from the outside space into the sensing area S. In this modified example, the storage means 1180 has in advance a calculation formula or a correspondence table for estimating the temperature of the air flowing from the outside space into the sensing area S from the measurement of the thermometer 105.

[0064] In this modified example, the temperature signal acquisition means 1186 acquires the temperature signal output from the thermometer 105. The condensation estimation means 1188 estimates the temperature of the air flowing from the external space into the sensing area S from the temperature indicated by the temperature signal acquired by the temperature signal acquisition means 1186 from the thermometer 105, according to a calculation formula or correspondence table stored in the storage means 1180. Then, the condensation estimation means 1188 estimates whether or not condensation has occurred based on the temperature estimated from the measurement value of the thermometer 105 and the measurement value of the thermometer 1121.

[0065] Furthermore, if thermometer 1171 (or thermometer 119 in the modified example (2) described above) is functioning normally, the measurement value of that thermometer is used to estimate condensation. If thermometer 1171 (or thermometer 119 in the modified example (2) described above) malfunctions, the measurement value of thermometer 105 may be used instead to estimate condensation.

[0066] (4) The smoke detector 11 may have a second light-emitting unit for detecting dirt in the sensing area S, separate from the light-emitting unit 111 (first light-emitting unit), and the condensation estimation means 1188 may estimate the presence or absence of condensation based on the measured values ​​of the thermometer 1121 and thermometer 1171, the measured value of the hygrometer 116, and the measured value of the light-receiving unit 112 when the second light-emitting unit is emitting light.

[0067] Figure 10 is a schematic diagram showing the configuration of the smoke detector 11 according to this modified example. The smoke detector 11 according to this modified example differs from the smoke detector 11 according to the embodiment described above in that it includes a light-emitting unit 120 (an example of a second light-emitting unit).

[0068] The light-emitting unit 120 is a light-emitting unit for detecting dirt on the lens 113, and is positioned, for example, outside the airflow path within the sensing area S, and closer to the lens 113 than the light-emitting unit 111. Therefore, the intensity of the light emitted from the light-emitting unit 120 and received by the light-receiving unit 112 is not substantially affected by particles in the air flowing from the intake port P to the exhaust port Q, and changes mainly depending on the degree of dirt on the lens 113.

[0069] Figure 11 shows the functional configuration of the control unit 118 according to this modified example. The control unit 118 according to this modified example differs from the control unit 118 according to the embodiment described above in that it includes a light emission instruction means 1192 for instructing the light emission unit 120 to emit light, and a dirt estimation means 1193 for estimating the degree of dirt on 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.

[0070] In this modified example, the storage means 1180 stores data showing the correspondence between the light intensity signal output by the light receiving unit 112 when the light emitting unit 120 is emitting light and the degree of dirt on the lens 113, and the dirt estimation means 1193 uses this data to estimate the degree of dirt on the lens 113.

[0071] The smoke detection means 1187 determines the presence or absence of smoke by correcting the light intensity indicated by the light intensity signal output by the light receiving unit 112 when the light emitting unit 111 is emitting light, or the range of light intensity indicated by the smoke detection condition data, according to the degree of dirt on the lens 113 estimated by the dirt estimation means 1193.

[0072] The condensation estimation means 1188, in reference to the dew point temperature data (Figure 5), estimates that condensation is occurring based on the temperatures measured by thermometers 1121 and 1171 and the humidity measured by hygrometer 116, and instructs the light emission instruction means 1192 to emit light from the light emission unit 120. Then, the condensation estimation means 1188 compares the light intensity indicated by the light intensity signal output from the light receiving unit 112 and acquired by the light intensity signal acquisition means 1182 when the light emission unit 120 is emitting light according to that instruction with the light intensity during normal operation when condensation is not occurring.

[0073] The condensation estimation means 1188 determines that condensation is occurring and generates condensation estimation data only when the light intensity indicated by the light intensity signal output from the light receiving unit 112 while the light emitting unit 120 is emitting light differs from the normal light intensity by a threshold or more.

[0074] According to this modification, for example, if the measurements of thermometer 1121, thermometer 1171, or hygrometer 116 contain errors and those measurements indicate the occurrence of condensation in light of the dew point temperature data, but condensation is not actually occurring, then false alarms of condensation occurrence are prevented.

[0075] (5) In the embodiment described above, the temperature of the lens 113 is measured by the thermometer 1121 provided in the light-receiving unit 112. Alternatively, the temperature of the lens 113 may be measured by a thermometer different from the thermometer 1121. With this modification, even if the temperature of the lens 113 cannot be accurately measured by the thermometer 1121 provided in the light-receiving unit 112 for reasons such as the light-receiving unit 112 and the lens 113 being far apart, the condensation estimation means 1188 can estimate whether or not condensation has occurred.

[0076] (6) When condensation occurs, false detection of smoke is more likely than when condensation does not occur. Therefore, if the condensation estimation means 1188 estimates that condensation is occurring, the smoke determination means 1187 may perform the determination of the presence or absence of smoke under stricter conditions than in normal circumstances (when it is estimated that no condensation is occurring).

[0077] In this modified example, for instance, the storage means 1180 stores smoke detection condition data for normal operation and for condensation occurrence. As previously described, the smoke detection condition data indicates, for example, a range of light intensity and a threshold for duration as conditions for determining the presence or absence of smoke. The range of light intensity indicated by the smoke detection condition data for condensation occurrence is narrower than the range of light intensity indicated by the smoke detection condition data for normal operation. Also, the duration indicated by the smoke detection condition data for condensation occurrence is longer than the duration indicated by the smoke detection condition data for normal operation.

[0078] While the condensation estimation means 1188 estimates that no condensation is occurring, the smoke determination means 1187 determines the presence or absence of smoke using smoke detection condition data for normal conditions. On the other hand, while the condensation estimation means 1188 estimates that condensation is occurring, the smoke determination means 1187 determines the presence or absence of smoke using smoke detection condition data for when condensation occurs.

[0079] According to this modification, the presence or absence of smoke is determined under stricter conditions while condensation is presumed to be occurring, thus reducing the occurrence of false alarms for smoke caused by condensation.

[0080] (7) In the above-described embodiment, the presence or absence of condensation on the lens 113 is estimated. The lens 113 is just one example of an object for which the smoke detector 11 estimates the presence or absence of condensation; any structure within the sensing region S may be used as the object for which the presence or absence of condensation is estimated. For example, if the smoke detector 11 is equipped with a lens for directing the light emitted by the light-emitting part 111 to a predetermined range, the presence or absence of condensation on that lens may be estimated. Alternatively, the presence or absence of condensation on the wall 1101 forming the sensing region S may also be estimated.

[0081] (8) In the embodiment described above, the condensation estimation means 1188 estimates whether or not condensation occurs using dew point temperature data (Figure 5). Alternatively, the condensation estimation means 1188 may calculate the dew point temperature according to a formula for calculating dew point temperature that uses the temperature of the air surrounding the object and the relative humidity of that air as variables, and then estimate whether or not condensation occurs by comparing the calculated dew point temperature with the measurement value of the thermometer 1121.

[0082] (9) In the embodiments described above, the hardware of the control unit 118 was assumed to be a computer, but the control unit 118 may be configured as a dedicated device having an integrated circuit such as an ASIC or FPGA. [Explanation of Symbols]

[0083] 1...Smoke detection system, 10...Computer, 11...Smoke detector, 12...Higher-level system, 101...Processor, 102...Memory, 103...Input / Output interface, 104...Communication interface, 105...Thermometer, 110...Housing, 111...Light-emitting unit, 112...Light-receiving unit, 113...Lens, 114...Fan, 115...Filter, 116...Hygrometer, 117...Flow meter, 118...Control unit, 119...Thermometer, 120...Light-emitting unit, 1101...Wall, 1102... Tube, 1103...Tube, 1121...Thermometer, 1171...Thermometer, 1180...Memory means, 1181...Light emission indicator means, 1182...Light intensity signal acquisition means, 1183...Temperature signal acquisition means, 1184...Humidity signal acquisition means, 1185...Flow rate signal acquisition means, 1186...Temperature signal acquisition means, 1187...Smoke detection means, 1188...Condensation estimation means, 1189...Flow rate abnormality detection means, 1190...Communication means, 1191...Timekeeping means, 1192...Light emission indicator means, 1193...Dirt estimation means.

Claims

1. A smoke detector 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, A means of emitting light, A light-receiving means for receiving light, A first temperature measuring means for measuring temperature, A second temperature measuring means is positioned upstream of the first temperature measuring means in the airflow path, A humidity measuring means for measuring humidity, A condensation estimation means that determines the dew point temperature based on the measurement value of the second temperature measuring means and the measurement value of the humidity measuring means, and estimates the presence or absence of condensation within the sensing area based on the comparison result between the determined dew point temperature and the measurement value of the first temperature measuring means. A smoke detector equipped with the following features.

2. A smoke detector that detects the generation of smoke in an external space by sensing particles contained in the air flowing into the sensing area from the external space, A means of emitting light, A lens that focuses light, A light receiving means for receiving light focused by the aforementioned lens, A temperature measuring means for measuring temperature, A humidity measuring means for measuring humidity, A condensation estimation means calculates the temperature of the lens based on the change in temperature over time indicated by the temperature measurement means, and estimates whether or not condensation is present in the sensing area based on the calculated temperature of the lens, the temperature of the air in the sensing area indicated by the temperature measurement means, and the humidity measurement means. A smoke detector equipped with the following features.

3. The light-emitting means includes a first light-emitting unit for detecting smoke and a second light-emitting unit for detecting dirt within the detection area. The condensation estimation means uses the measurement value of the light receiving means when the second light-emitting unit is emitting light to estimate whether or not condensation is present. A smoke detector according to claim 1 or 2.

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