Smoke detector

Abstract

To provide a smoke detector capable of detecting smoke more quickly than a conventional smoke detector.SOLUTION: The smoke detector 11 includes a light emitting unit 111, a light receiving unit 113, a light receiving unit 114, and a control unit 118. The light receiving unit 113 receives scattered light that is emitted from the light emitting unit 111 and scattered by the particles contained in the air in the region A. The light receiving unit 114 receives reflected light that is emitted from the light emitting unit 111 and reflected by a particle passing through the position B. The control unit 118 measures the number of particles that have passed through position B within the most recent period of a predetermined length of time by counting the pulse waves that appear in the change over time of the light intensity signal outputted from the light receiver 114. The control unit 118 determines the presence or absence of smoke in the external space based on the number of particles thus measured and the amplitude of the light intensity signal output from the light receiving part 113.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to smoke sensing technology. [Background technology]

[0002] 2. Description of the Related Art There are smoke detectors that detect the generation of smoke in an external space by detecting particles contained in the air that flows into a detection area from the external space.

[0003] A smoke detector called a photoelectric smoke detector emits light from a light-emitting element into a sensing area, and the light is reflected by particles in the air within the sensing area and received by a light-receiving element.The detector detects the occurrence of smoke in the external space based on the intensity of the light received and measured by the light-receiving element.

[0004] One type of photoelectric smoke detector is known to measure the intensity of scattered light, which is a collection of light reflected by particles contained in the air flowing into the detection area, and determine the presence or absence of smoke from that intensity (hereinafter referred to as the "total scattered light method"). Patent document 1, for example, is an example of a patent document disclosing technology related to a photoelectric smoke detector using the total scattered light method.

[0005] Another known type of photoelectric smoke detector is one that measures the intensity of light reflected by particles passing through a predetermined position within the detection area, measures the particle diameter (particle size) and number (particle count) from that intensity, and determines the presence or absence of smoke from these measurement results (hereinafter referred to as the "particle counter method"). Patent document 2, for example, is an example of a patent document that discloses technology related to a particle counter type photoelectric smoke detector. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 61-53550 [Patent Document 2] Japanese Patent Application Publication No. 11-23460 Summary of the Invention [Problem to be solved by the invention]

[0007] In the case of a photoelectric smoke detector using the total scattered light method, smoke is not detected until the concentration of smoke in the detection area increases and the intensity of light received by the light-receiving element reaches a predetermined threshold. In the case of a photoelectric smoke detector using the particle counter method, smoke is not detected until the concentration of smoke in the detection area increases and the number of smoke particles passing through a predetermined position within the detection area reaches a predetermined threshold. Therefore, with either method of photoelectric smoke detector, it takes a certain amount of time from the occurrence of smoke until the smoke is detected.

[0008] In view of the above circumstances, the present invention provides a smoke detector that can detect smoke more quickly than conventional smoke detectors. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention provides: We propose a smoke detector that includes a first light intensity measuring means that measures the intensity of a collection of light reflected by a group of particles contained in air flowing from external space into a specified area within the sensing area, a second light intensity measuring means that measures the intensity of light reflected by each individual particle that flows in from the external space and passes through a specified position within the sensing area, and a determination means that determines the presence or absence of smoke in the external space based on the measurement values ​​of the first light intensity measuring means and the second light intensity measuring means. [Effects of the Invention]

[0010] According to the present invention, the presence or absence of smoke is determined based on both the intensity of reflected light generated by individual smoke particles and the intensity of scattered light generated by groups of smoke particles, so smoke can be detected more quickly than when either method is used alone. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing the configuration of a smoke detection system according to an embodiment; [Figure 2]1 is a diagram illustrating a configuration of a smoke detector according to an embodiment; [Figure 3] FIG. 2 is a diagram showing the configuration of a computer employed as hardware of a control unit according to an embodiment. [Figure 4] FIG. 2 is a diagram showing the functional configuration of a control unit according to an embodiment. [Figure 5] 6 is a graph showing changes over time in the amplitude of light intensity signals output from two light receiving units included in a smoke sensor according to one embodiment. [Figure 6] FIG. 10 is a diagram illustrating a flow of processing performed by a determination unit according to an embodiment. [Figure 7] FIG. 10 is a diagram illustrating a flow of processing performed by a determination unit according to a modified example. [Figure 8] 10 is a graph showing how the shape of a pulse indicated by a light intensity signal output from a light receiving unit according to one modification changes depending on particle size. [Figure 9] FIG. 10 is a diagram showing the functional configuration of a control unit according to a modified example. [Figure 10] FIG. 10 is a diagram schematically illustrating the configuration of a smoke detector according to a modified example. [Figure 11] FIG. 10 is a diagram schematically illustrating the configuration of a smoke detector according to a modified example. [Figure 12] FIG. 10 is a diagram schematically illustrating the configuration of a smoke detector according to a modified example. [Figure 13] FIG. 10 is a diagram showing the functional configuration of a control unit according to a modified example.

[0012] [Embodiment] A smoke detection system 1 according to one 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 a host system 12.

[0013] The smoke detector 11 is a device that is placed in a space to be monitored for smoke generation (hereinafter referred to as the "monitored space"), takes in the air in the monitored space, detects smoke if it is contained in the air that has been taken in, and notifies the host system 12 of the occurrence of smoke if smoke is detected.

[0014] In FIG. 1, the smoke detection system 1 includes one smoke detector 11, but the number of smoke detectors 11 included in the smoke detection system 1 varies depending on the number and size of monitored spaces.

[0015] The host system 12 may be a monitoring terminal device, a smoke alarm panel, a central monitoring system, etc. The host system 12 and the smoke detector 11 can communicate data with each other via a wired, wireless, or mixed communication medium.

[0016] The host system 12 is similar to a host system according to the prior art, and therefore a description thereof will be omitted.

[0017] 2 is a diagram showing a schematic configuration of smoke detector 11. Smoke detector 11 includes housing 110, light emitter 111, lens 112, light receiver 113, light receiver 114, lens 115, fan 116, filter 117, and control unit 118.

[0018] 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 from the internal space to the external space.

[0019] The housing 110 also has a wall 1101 for forming a sensing area S, which is an area for sensing smoke within the internal space, a pipe 1102 for forming an air flow path from the intake port P to the sensing area S, and a pipe 1103 for forming an air flow path from the sensing area S to the exhaust port Q.

[0020] The light emitting unit 111 (an example of a light emitting means) has, for example, an LED (an example of a light emitting element), and emits light toward the air flow path from the intake port P toward the exhaust port Q.

[0021] The lens 112 serves to collect the light emitted by the light emitting unit 111 and guide the collected light to a position B within the sensing area S.

[0022] The light receiving unit 113 (an example of a first light intensity measuring means) has, for example, a photodiode (an example of a light receiving element), and receives a part of scattered light, which is a collection of reflected light that is generated when light irradiated from the light emitting unit 111 is reflected by a group of particles contained in the air that flows from the external space into the region A within the sensing region S, and outputs a light intensity signal indicating the intensity of the received light to the control unit 118. The light receiving unit 113 is arranged at a position that does not face the light emitting unit 111 so that the light emitted by the light emitting unit 111 does not directly enter the light receiving unit 113.

[0023] The light receiving unit 114 (an example of a second light intensity measuring means) has, for example, a photodiode (an example of a light receiving element), and receives a portion of the light reflected by each particle when light irradiated from the light emitting unit 111 flows in from the external space and passes through position B in the sensing area S, and outputs a light intensity signal indicating the intensity of the received light to the control unit 118. The light receiving unit 114 is arranged at a position not facing the light emitting unit 111 so that the light emitted by the light emitting unit 111 does not directly enter the light receiving unit 114.

[0024] Lens 115 is a lens that focuses light traveling from position B toward light receiving unit 114. In other words, the focal point of lens 115 is position B. Lens 115 enables light receiving unit 114 to capture light reflected by smoke particles within an area that is centered at position B and is so narrow that no more than two smoke particles can enter at the same time, and that can be considered to be essentially a point.

[0025] The fan 116 generates a flow of air by rotating blades that flows from the external space through the intake port P into the sensing area S and then flows out through the exhaust port Q into the external space.

[0026] The filter 117 is disposed on the air flow path from the intake port P to the exhaust port Q, and captures dust contained in the air flowing into the sensing area S from the external space, thereby preventing the dust from entering the sensing area S.

[0027] The control unit 118 is a device that controls the operation of the smoke detector 11. The hardware of the control unit 118 is, for example, a computer, and the control unit 118 is realized by the computer performing processing in accordance with a program for the control unit 118.

[0028] 3 is a diagram showing the configuration of a computer 10 employed as hardware for the control unit 118. The computer 10 includes a processor 101 that performs various types of data processing, a memory 102 that stores various types of data, an input / output interface 103 that exchanges signals with components such as the light-emitting unit 111 of the smoke detector 11, and a communication interface 104 that exchanges data with an external device (in this case, the host system 12).

[0029] Fig. 4 is a diagram showing the functional configuration of control unit 118. That is, control unit 118 including the components shown in Fig. 4 is realized by computer 10 performing processing in accordance with a program for control unit 118. The functional components of control unit 118 are described below.

[0030] The light emission instruction means 1181 instructs the light emitting unit 111 to emit light. The light intensity signal acquisition means 1182 acquires the light intensity signal output from the light receiving unit 113. The light intensity signal acquisition means 1183 acquires the light intensity signal output from the light receiving unit 114.

[0031] The timekeeping means 1184 continuously measures the current time based on a clock signal generated by a clock included in the processor 101, for example, and generates a time signal indicating the current time.

[0032] The counting means 1185 (which constitutes the particle number measuring means together with the light receiving unit 114 and the light intensity signal acquiring means 1183) counts the number of particles (hereinafter referred to as "particle number") that have passed through position B within the most recent predetermined time period, based on the light intensity signal acquired from the light receiving unit 114 by the light intensity signal acquiring means 1183. Note that the counting means 1185 uses the time signal generated by the timing means 1184 to identify the most recent predetermined time period for which the particle number is to be counted.

[0033] The determination means 1186 determines the presence or absence of smoke in the external space based on the light intensity indicated by the light intensity signal acquired by the light intensity signal acquisition means 1182 and the number of particles counted by the counting means 1185. The procedure by which the determination means 1186 determines the presence or absence of smoke will be described later.

[0034] When the determining means 1186 determines that smoke is present in the external space, the communication means 1187 transmits smoke occurrence notification data notifying the host system 12 of the occurrence of smoke.

[0035] Figure 5 is a graph showing the change over time in the amplitude of the light intensity signal acquired by the light intensity signal acquisition means 1182 from the light receiving unit 113 (Figure 5(a)), and the change over time in the amplitude of the light intensity signal acquired by the light intensity signal acquisition means 1183 from the light receiving unit 114 (Figure 5(b)), when air containing smoke begins to flow into the sensing area S from the external space.

[0036] The light intensity signal acquired by the light intensity signal acquiring means 1182 from the light receiving unit 113 indicates the intensity of the entire reflected light that has reached the light receiving unit 113 out of the light reflected by a plurality of particles (particle group) within an area A having a certain size. Therefore, the amplitude of the light intensity signal acquired by the light intensity signal acquiring means 1182 from the light receiving unit 113 changes continuously in accordance with changes in the concentration of smoke within the sensing area S.

[0037] On the other hand, the light intensity signal acquired by the light intensity signal acquiring means 1183 from the light receiving unit 114 indicates the intensity of the reflected light that reaches the light receiving unit 114 out of the light reflected by particles passing through an extremely narrow area centered on position B, which can be considered to be essentially a point. Therefore, the light intensity signal acquired by the light intensity signal acquiring means 1183 from the light receiving unit 114 is a pulse signal that rises at the moment a particle passes position B. Then, as the concentration of smoke in the sensing area S changes, the frequency of occurrence of these pulse signals, i.e., the number of occurrences per given time, changes.

[0038] The counting means 1185 counts the number of pulse signals indicated by the light intensity signal acquired by the light intensity signal acquiring means 1183 from the light receiving unit 114 .

[0039] Fig. 6 is a diagram illustrating a flow of processing performed by the determination means 1186. The determination means 1186 performs processing according to the flow shown in Fig. 6 every time a sufficiently short predetermined time elapses. The processing performed by the determination means 1186 will be described below.

[0040] The determining means 1186 first determines whether or not the light intensity signal acquired by the light intensity signal acquiring means 1182 from the light receiving unit 113 reaches a predetermined threshold value Z (step S101).

[0041] In step S101, if the light intensity signal acquiring means 1182 determines that the light intensity signal acquired from the light receiving unit 113 does not reach the threshold value Z (step S101; No), the determining means 1186 sets a predetermined value X to the threshold value T used in the determination in step S104 (step S102).

[0042] On the other hand, in step S101, if the light intensity signal acquiring means 1182 determines that the light intensity signal acquired from the light receiving unit 113 reaches the threshold value Z (step S101; Yes), the determining means 1186 sets a predetermined value Y smaller than the value X to the threshold value T used in the determination in step S104 (step S103).

[0043] Following the processing of step S102 or S103, the determining means 1186 determines whether the number of grains counted by the counting means 1185 has reached the threshold value T set in step S102 or S103 (step S104).

[0044] In step S104, when it is determined that the number of particles counted by the counting means 1185 has reached the threshold value T (step S104; Yes), the determining means 1186 determines that smoke is occurring in the external space, and instructs the communication means 1187 to transmit smoke occurrence notification data (step S105). The communication means 1187 transmits the smoke occurrence notification data to the upper system 12 in accordance with the instruction of the determining means 1186. Thereafter, the determining means 1186 ends the series of processes shown in FIG. 6.

[0045] On the other hand, in step S104, if it is determined that the number of particles counted by the counting means 1185 has not reached the threshold value T (step S104; No), the determination means 1186 determines that smoke is not occurring in the external space, and terminates the series of processes shown in Figure 6 without instructing the communication means 1187 to send smoke occurrence notification data.

[0046] As described above, the determination means 1186 determines the presence or absence of smoke in the external space in accordance with the determination condition of whether or not the number of particles that have passed through position B within the most recent predetermined time period, as counted by the counting means 1185, has reached threshold value T. Then, when the light intensity signal received by the light intensity signal acquisition means 1182 from the light receiving unit 113 has reached predetermined threshold value Z, the determination means 1186 changes the threshold value T to value Y, which is smaller than the normally used value X. As a result, smoke is detected more quickly compared to when such a change in threshold value T is not made.

[0047] [Variation] The above-described embodiment is a specific example of the present invention, and various modifications are possible within the scope of the technical concept of the present invention. Examples of such modifications are shown below. Note that two or more of the following modifications may be combined as appropriate.

[0048] (Variation 1) In the above-described embodiment, the determination means 1186 changes the conditions for determining whether or not smoke is present based on the number of particles counted by the counting means 1185 (i.e., the conditions for determining whether or not smoke is present by the particle number measuring means) based on the light intensity signal acquired by the light intensity signal acquisition means 1182 from the light receiving unit 113 (i.e., the measurement value of the light intensity measuring means).

[0049] Alternatively, a configuration may be adopted in which the determination means 1186 determines whether or not smoke is present based on the light intensity signal acquired by the light intensity signal acquisition means 1182 from the light receiving unit 113, and changes the determination conditions (i.e., the conditions for determining whether or not smoke is present by the light intensity measurement means) based on the number of particles counted by the counting means 1185 (i.e., the measurement value of the particle number measurement means).

[0050] Fig. 7 is a diagram illustrating the flow of processing performed by the determination means 1186 in one example of this modification. The determination means 1186 performs processing according to the flow shown in Fig. 7 every time a sufficiently short predetermined time elapses. The processing performed by the determination means 1186 shown in Fig. 7 will be described below.

[0051] The determining means 1186 first determines whether or not the number of grains counted by the counting means 1185 has reached a predetermined threshold value Y (step S201).

[0052] In step S201, if it is determined that the number of grains counted by the counting means 1185 does not reach the threshold value Y (step S201; No), the judgment means 1186 sets a predetermined value W to the threshold value T used in the judgment in step S204 (step S202).

[0053] On the other hand, in step S201, if it is determined that the number of grains counted by the counting means 1185 has reached a predetermined threshold Y (step S201; Yes), the judgment means 1186 sets a predetermined value Z smaller than the value W as the threshold T used in the judgment in step S204 (step S203).

[0054] Following the processing of step S202 or S203, the determination means 1186 determines whether the light intensity signal acquired by the light intensity signal acquisition means 1182 from the light receiving unit 113 reaches the threshold value T whose value was set in step S202 or S203 (step S204).

[0055] In step S204, when the light intensity signal acquiring means 1182 determines that the light intensity signal acquired from the light receiving unit 113 reaches the threshold value T (step S204; Yes), the determining means 1186 determines that smoke is occurring in the external space, and instructs the communication means 1187 to transmit smoke occurrence notification data (step S205). The communication means 1187 transmits the smoke occurrence notification data to the upper system 12 in accordance with the instruction of the determining means 1186. Thereafter, the determining means 1186 ends the series of processes shown in FIG. 7.

[0056] On the other hand, in step S204, if the light intensity signal acquisition means 1182 determines that the light intensity signal acquired from the light receiving unit 113 does not reach the threshold value T (step S204; No), the determination means 1186 determines that no smoke is occurring in the external space, and terminates the series of processes shown in Figure 7 without instructing the communication means 1187 to send smoke occurrence notification data.

[0057] In this modified example, the determination means 1186 determines whether or not smoke is present in the external space in accordance with the determination condition of whether or not the intensity of scattered light generated by the particle group in area A, which is indicated by the light intensity signal acquired by the light intensity signal acquisition means 1182, has reached a threshold value T. Then, when the number of particles counted by the counting means 1185 has reached a predetermined threshold value Y, the determination means 1186 changes the threshold value T to a value Z which is smaller than the normally used value W. As a result, smoke is detected more quickly compared to when the threshold value T is not changed in this way.

[0058] Furthermore, the smoke detector 11 according to this modified example can determine the presence or absence of smoke in the external space that has particle sizes that cannot be measured by particle number measuring means.

[0059] For example, when the particle size of smoke is small, such as black smoke, even if a smoke particle passes through position B, the amount of light reflected by the particle and reaching the light receiving unit 114 may be small, and no clear pulse signal may appear in the light intensity signal output from the light receiving unit 114. In such a case, smoke cannot be detected based solely on the number of particles counted by the counting means 1185.

[0060] However, in this modified example, even if the particle size of the smoke is small, if a large number of particles are present in area A, the amount of reflected light that is reflected by the particle group and reaches the light receiving unit 113 will be sufficiently large. Therefore, the determination in step S204 becomes Yes, and smoke is detected.

[0061] (Variation 2) In the above-described embodiment, the condition for determining whether or not smoke is present using the particle number measurement means is whether or not the particle number has reached a predetermined threshold value, but the condition for determining whether or not smoke is present using the particle number measurement means is not limited to this.

[0062] For example, a determination criterion may be adopted that determines that smoke is being generated when the number of particles reaches a predetermined threshold and continues for a predetermined period of time or longer. In this example, the determination means 1186 may change the threshold related to the duration in addition to or instead of changing the threshold related to the number of particles included in the determination criterion based on the measurement value of the light intensity measurement means.

[0063] For example, when the light intensity signal acquired by the light intensity signal acquisition means 1182 from the light receiving unit 113 does not reach threshold Z, the determination means 1186 determines that smoke is occurring when the time during which the number of particles counted by the counting means 1185 reaches threshold X continues to be equal to or greater than threshold T1. On the other hand, when the light intensity signal acquired by the light intensity signal acquisition means 1182 from the light receiving unit 113 reaches threshold Z, the determination means 1186 determines that smoke is occurring when the time during which the number of particles counted by the counting means 1185 reaches threshold X continues to be equal to or greater than threshold T2, which is smaller than threshold T1.

[0064] Similarly, in the above-mentioned variant example 1, the condition for determining whether or not smoke is present using the light intensity measuring means is whether or not the light intensity reaches a predetermined threshold, but the condition for determining whether or not smoke is present using the light intensity measuring means is not limited to this.

[0065] For example, a determination criterion may be adopted that determines that smoke is being generated when the state in which the light intensity reaches a predetermined threshold continues for a predetermined period of time or longer. In this example, the determination means 1186 may change the threshold related to the duration in addition to or instead of changing the threshold related to the light intensity included in the determination criterion based on the measurement value of the particle number measurement means.

[0066] For example, when the number of particles counted by the counting means 1185 has not reached threshold Y, the determining means 1186 determines that smoke is being generated when the time during which the light intensity signal acquired by the light intensity signal acquiring means 1182 from the light receiving unit 113 has reached threshold W continues to be equal to or greater than threshold T1. On the other hand, when the number of particles counted by the counting means 1185 has reached threshold Y, the determining means 1186 determines that smoke is being generated when the time during which the light intensity signal acquired by the light intensity signal acquiring means 1182 from the light receiving unit 113 has reached threshold W continues to be equal to or greater than threshold T2, which is smaller than threshold T1.

[0067] (Variation 3) The shape of the pulse indicated by the light intensity signal acquired by the light intensity signal acquiring means 1183 from the light receiving unit 114 changes depending on the particle size of the particle passing through position B. Fig. 8 is a graph showing how the shape of the pulse indicated by the light intensity signal acquired by the light intensity signal acquiring means 1183 from the light receiving unit 114 changes depending on the particle size.

[0068] Figure 8(a) is a graph showing the change over time in the light intensity signal when a particle with a larger diameter compared to Figure 8(b) passes through position B, and Figure 8(b) is a graph showing the change over time in the light intensity signal when a particle with a smaller diameter compared to Figure 8(a) passes through position B. Note that Figures 8(a) and 8(b) are graphs for the case where the flow velocity (flow rate per unit time) of the air flowing through the sensing area S is the same.

[0069] As shown in Fig. 8, the larger the particle size of a particle passing through position B, the larger the width in the time axis direction of the pulse appearing in the light intensity signal. In general, the larger the particle size of a particle passing through position B, the larger the amplitude of the pulse appearing in the light intensity signal.

[0070] Therefore, based on the light intensity signal acquired by the light intensity signal acquiring means 1183 from the light receiving unit 114, the particle size of particles contained in the air flowing into the sensing area S from the external space, i.e., the particle size of smoke, can be identified.

[0071] Incidentally, when smoke is present in the sensing area S, the concentration of the smoke will differ if the particle size of the smoke is different, even if the light intensity indicated by the light intensity signal acquired by the light intensity signal acquiring means 1182 from the light receiving unit 113 is the same. Generally, when the light intensity indicated by the light intensity signal acquired by the light intensity signal acquiring means 1182 from the light receiving unit 113 is the same, the smaller the particle size of the smoke, the higher the concentration of the smoke.

[0072] Therefore, the smoke detector 11 may be configured to determine whether or not smoke is occurring in the external space based on the amplitude of the light intensity signal acquired by the light intensity signal acquisition means 1182 from the light receiving unit 113 and the particle size of the smoke identified based on the shape (width in the time axis direction or amplitude) of the pulse appearing in the light intensity signal acquired by the light intensity signal acquisition means 1183 from the light receiving unit 114.

[0073] Fig. 9 is a diagram showing the functional configuration of a control unit 118 provided in a smoke detector 11 according to this modification. Some of the components shown in Fig. 9 are common to the components of the control unit 118 according to the embodiment shown in Fig. 4. These components are designated by the same reference numerals as those used in Fig. 4. Below, the components shown in Fig. 9 that differ from the components shown in Fig. 4 will be described.

[0074] The particle size calculation means 1188 calculates the particle size of a particle passing through position B. Specifically, the particle size calculation means 1188 calculates the particle size of a particle passing through position B by multiplying the width (or amplitude) in the time axis direction of a pulse wave appearing in the change over time of the light intensity signal acquired by the light intensity signal acquisition means 1183 from the light receiving unit 114 by the flow velocity (flow rate per unit time) of air flowing through the sensing area S. Alternatively, for example, the particle size calculation means 1188 may identify the particle size of a particle passing through position B according to a correspondence table showing particle sizes corresponding to the width (or amplitude) in the time axis direction of the pulse wave, or a calculation formula for calculating particle size using the width (or amplitude) in the time axis direction of the pulse wave as a variable. The particle size calculation means 1188, together with the light receiving unit 114 and the light intensity signal acquisition means 1183, constitutes particle size measurement means for measuring the particle size of particles contained in the air flowing into the sensing area S from external space.

[0075] In addition, if the flow velocity of the air flowing through the sensing area S changes, the smoke sensor 11 can be configured to include a flow meter that measures the flow velocity, and the particle size calculation means 1188 can calculate the particle size by multiplying the width of the pulse wave in the time axis direction by the flow velocity obtained as a measurement result of the flow meter.

[0076] The determination means 1189 determines whether smoke is occurring in the external space based on the particle size calculated by the particle size calculation means 1188 (i.e., the measurement value of the particle size measurement means) and the light intensity indicated by the light intensity signal acquired by the light intensity signal acquisition means 1182 from the light receiving unit 113 (i.e., the measurement value of the light intensity measurement means).

[0077] For example, the determination means 1189 determines the smoke concentration according to the particle size calculated by the particle size calculation means 1188 and the light intensity indicated by the light intensity signal acquired from the light receiving unit 113 by the light intensity signal acquisition means 1182, in accordance with a correspondence table showing the smoke concentration according to the combination of particle size and light intensity. Alternatively, the determination means 1189 may calculate the smoke concentration according to a calculation formula for the smoke concentration that uses particle size and light intensity as variables.

[0078] The determination means 1189 determines that smoke is occurring in the external space when the density of smoke identified as described above reaches a predetermined threshold. Note that the determination condition used by the determination means 1189 to determine the presence or absence of smoke is not limited to this. For example, a determination condition may be adopted that determines that smoke is occurring in the external space when the state in which the density of smoke identified by the determination means 1189 has reached the predetermined threshold continues for a predetermined period of time or longer.

[0079] Furthermore, the determination means 1189 does not necessarily need to specify the concentration of smoke. For example, instead of comparing the concentration of smoke with a threshold, the determination means 1189 may adopt a configuration in which the presence or absence of smoke is determined by comparing the light intensity indicated by the light intensity signal acquired from the light-receiving unit 113 by the light intensity signal acquisition means 1182 with a threshold, and the light intensity indicated by the light intensity signal acquired from the light-receiving unit 113 or the threshold of the light intensity used to determine the presence or absence of smoke may be adjusted according to the particle size calculated by the particle size calculation means 1188.

[0080] For example, the smaller the identified particle size, the larger the multiplier the determination means 1189 applies to the light intensity indicated by the light intensity signal acquired from the light receiving unit 113, thereby correcting the measurement value of the light receiving unit 113. The determination means 1189 compares the measurement value of the light intensity thus corrected with a threshold value to determine whether or not smoke is being generated.

[0081] Alternatively, the smaller the identified particle size, the smaller the light intensity threshold value used to determine whether or not smoke is present, and the determination means 1189 corrects the threshold value by multiplying the threshold value by a smaller multiplier. The determination means 1189 compares the light intensity threshold value thus corrected with the light intensity indicated by the light intensity signal acquired from the light receiving unit 113, and determines whether or not smoke is present.

[0082] As described above, the particle size calculated by the particle size calculation means 1188 is used to adjust the measurement value of the light receiving unit 113 or the threshold value to be compared with the measurement value of the light receiving unit 113. Therefore, the particle size calculated by the particle size calculation means 1188 only needs to be an index value indicating the size of the particle diameter, and does not necessarily have to be a numerical value that represents the particle diameter in terms of its length (μm). Therefore, for example, the width of the pulse wave in the time axis direction may be used directly as a value indicating the particle size. Also, the amplitude of the pulse wave may be used directly as a value indicating the particle size.

[0083] When the determination means 1189 detects smoke, the communication means 1190 transmits particle size notification data notifying the particle size calculated by the particle size calculation means 1188 together with the smoke detection notification data to the host system 12. The particle size indicated by the particle size notification data is information indicating the type of smoke (black smoke, white smoke, etc.), and for example, a manager or the like who receives a notification of smoke occurrence via the host system 12 can use the particle size notified at the same time to identify the source of the fire, identify an appropriate fire extinguishing method, etc.

[0084] (Variation 4) In the above-described embodiment, the scattered light, which is a collection of light reflected by a group of particles in region A received by light receiving unit 113, and the reflected light reflected by particles passing through position B received by light receiving unit 114, are light emitted from the same light emitter 111. Alternatively, a configuration may be adopted in which the light source of the light received by light receiving unit 113 and the light source of the light received by light receiving unit 114 are different.

[0085] Fig. 10 is a diagram schematically illustrating the configuration of an example of a smoke sensor 11 according to such a modified example. The smoke sensor 11 shown in Fig. 10 includes a light-emitting unit 111(1) and a light-emitting unit 111(2).

[0086] The light-emitting unit 111(1) emits light toward the region A. The light-receiving unit 113 receives a portion of scattered light, which is a collection of light that is emitted from the light-emitting unit 111(1) and reflected by the particle group in the region A.

[0087] The light-emitting unit 111(2) emits light toward a position B in an area other than the area A. The light-receiving unit 114 receives a portion of the light that is emitted from the light-emitting unit 111(2) and reflected by particles passing through the position B.

[0088] Compared to the smoke detector 11 according to this modification, the smoke detector 11 according to the embodiment described above requires fewer light-emitting elements, which is desirable in that it can be made smaller and less expensive.

[0089] (Variation 5) In the above-described embodiment, the sensing area S including the area A that generates the scattered light received by the light receiving unit 113 and the sensing area S including the position B that generates the reflected light that is received by the light receiving unit 114 are the same area. Alternatively, the area A and the position B may be configured to be included in different sensing areas.

[0090] Fig. 11 is a diagram schematically illustrating the configuration of an example of a smoke detector 11 according to such a modification. Housing 110 of smoke detector 11 shown in Fig. 11 has therein two distinct sensing areas, sensing area S11 and sensing area S12. Here, the term "different sensing areas" refers to areas separated so that light emitted in one area does not substantially reach the other area, and does not necessarily mean completely separated areas. Sensing area S11 includes area A, and sensing area S12 includes position B.

[0091] 11 is provided with a light-emitting unit 111 that is disposed on the boundary between sensing area S11 and sensing area S12 and emits light to both sensing area S11 and sensing area S12. Note that light-emitting unit 111 may be configured with two different light-emitting units that are disposed in sensing area S11 and sensing area S12, respectively.

[0092] In addition, compared to the smoke detector 11 according to this modified example, the smoke detector 11 according to the embodiment described above is preferable in that it can be made smaller because the sensing area including area A and the sensing area including position B are the same area.

[0093] (Variation 6) In the above-described embodiment, the light receiving units 113 and 114 each include a different light receiving element (e.g., a photodiode) and receive light individually. Alternatively, the light receiving units 113 and 114 may be configured to measure the light intensity using the same light receiving element.

[0094] Fig. 12 is a diagram showing a schematic configuration of a smoke sensor 11 according to this modification, and Fig. 13 is a diagram showing the functional configuration of a control unit 118 according to this modification.

[0095] In this modification, light receiving unit 114 also serves the role of light receiving unit 113. Also, in this modification, smoke sensor 11 includes, in addition to light emitting unit 111, light emitting unit 119 that is different from light emitting unit 111. Light emitting unit 119 irradiates light widely onto area A that is closer to light receiving unit 114 than position B.

[0096] In this modified example, light emission instruction means 1191 issues light emission instructions to light-emitting unit 111 and light-emitting unit 119 so that they each emit light at different periods. That is, light-emitting unit 111 and light-emitting unit 119 emit light at different times and do not emit light simultaneously. When light-emitting unit 119 is emitting light, light-receiving unit 114 plays the role of light-receiving unit 113 (an example of first light-receiving means) in the above-described embodiment, and when light-emitting unit 111 is emitting light, light-receiving unit 114 plays the role of light-receiving unit 114 (an example of second light-receiving means) in the above-described embodiment.

[0097] The counting means 1185 and the determining means 1186 determine whether the light intensity signal received from the light receiving unit 114 via the light intensity signal acquiring means 1183 indicates the light intensity when either the light emitting unit 111 or the light emitting unit 119 is emitting light.

[0098] The counting means 1185 counts the number of particles that have passed through position B using the light intensity signal output by the light receiving unit 114 when the light emitting unit 111 is emitting light. The determining means 1186 determines the presence or absence of smoke based on the light intensity indicated by the light intensity signal output by the light receiving unit 114 when the light emitting unit 119 is emitting light and the number of particles counted by the counting means 1185.

[0099] In this modified example, light-emitting unit 111 and light-emitting unit 119 may be configured to emit light using the same light-emitting element (such as an LED). For example, instead of including light-emitting unit 119 shown in Fig. 12, smoke sensor 11 may be configured to include a mirror that moves in and out between light-emitting unit 111 and lens 112, and to guide light emitted from light-emitting unit 111 to area A when the mirror is between light-emitting unit 111 and lens 112. In this case, light-emitting unit 111 with the mirror between it and lens 112 plays the role of light-emitting unit 119 in Fig. 12.

[0100] (others) In the above-described embodiment, the hardware of the control unit 118 is 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]

[0101] 1...smoke detection system, 10...computer, 11...smoke detector, 12...host system, 101...processor, 102...memory, 103...input / output interface, 104...communication interface, 110...housing, 111...light emitting unit, 112...lens, 113...light receiving unit, 114...light receiving unit, 115...lens, 116...fan, 117...filter, 118...control unit, 119...light emitting unit, 1101...wall, 1102...tube, 1103...tube, 1181...light emission instruction means, 1182...light intensity signal acquisition means, 1183...light intensity signal acquisition means, 1184...timing means, 1185...counting means, 1186...determination means, 1187...communication means, 1188...particle size calculation means, 1189...determination means, 1190...communication means, 1191...light emission instruction means.

Claims

1. a first light intensity measuring means for measuring the intensity of a collection of light reflected by a group of particles contained in air flowing from an external space into a predetermined region within the sensing region; a second light intensity measuring means for measuring the intensity of light reflected by each individual particle that flows in from the external space and passes through a predetermined position within the sensing region; a particle size measuring means for measuring the particle size of a particle passing through the predetermined position based on the measurement value of the first light intensity measuring means and the measurement value of the second light intensity measuring means; A smoke detector equipped with:

2. a determination means for determining whether or not smoke is present in the external space based on the measurement value of the first light intensity measurement means and the particle diameters measured by the particle diameter measurement means; The smoke detector of claim 1 .

3. The determination means determines the concentration of smoke in the external space based on the measurement value of the first light intensity measurement means and the particle size measured by the particle size measurement means, and determines the presence or absence of smoke in the external space based on the determined concentration.

3. The smoke detector of claim 2.

4. The determination means adjusts the measurement value of the first light intensity measurement means or the threshold value of the light intensity used to determine the presence or absence of smoke, depending on the particle size calculated by the particle size measurement means.

4. A smoke detector according to claim 2 or 3.

5. and a communication means for outputting the particle size calculated by the particle size measuring means to an external device when smoke is detected by the determination means.

3. The smoke detector of claim 2.

6. a light emitting means for emitting light; The first light intensity measuring means and the second light intensity measuring means measure the intensity of reflected light of light emitted from the same light emitting means. A smoke detector according to any one of claims 1 to 5.

7. the first light intensity measuring means and the second light intensity measuring means measure the light intensity using the same light receiving element; the first light intensity measuring means measures the light intensity by the light receiving element when light is emitted to the predetermined region and when light is not emitted to the predetermined position; The second light intensity measuring means measures the intensity of light by the light receiving element when light is emitted to the predetermined position and when light is not emitted to the predetermined region. A smoke detector according to any one of claims 1 to 6.

8. The sensing area including the predetermined position and the sensing area including the predetermined area are the same area. A smoke detector according to any one of claims 1 to 7.

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