JP7767396B2 - smoke detector - Google Patents

Description

The present invention relates to technology for detecting smoke.

There are smoke detectors that detect the occurrence of smoke in an external space by detecting particles contained in the air flowing into the detection area from the external space.

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.

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.

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, determines 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 disclosing technology related to particle counter-type photoelectric smoke detectors.

Japanese Unexamined Patent Publication No. 61-53550 Japanese Patent Application Publication No. 11-23460

With a photoelectric smoke detector using the total scattered light method, smoke is not detected until the concentration of smoke within the detection area increases and the intensity of light received by the light-receiving element reaches a predetermined threshold. Furthermore, with a photoelectric smoke detector using the particle counter method, smoke is not detected until the concentration of smoke within 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 type of photoelectric smoke detector, it takes a certain amount of time from the time smoke is generated until it is detected.

In consideration of the above circumstances, the present invention provides a smoke detector that can detect smoke more quickly than conventional smoke detectors.

In order to solve the above problems, the present invention provides:
We propose a smoke detector comprising: 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 external space into a specified area within the sensing area; 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 specified position within the sensing area; and a determination means for determining 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.

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, allowing smoke to be detected more quickly than when relying on either method alone.

1 is a diagram showing the configuration of a smoke detection system according to an embodiment; 1 is a diagram illustrating a configuration of a smoke detector according to an embodiment; FIG. 2 is a diagram showing the configuration of a computer employed as hardware of a control unit according to an embodiment. FIG. 2 is a diagram showing the functional configuration of a control unit according to an embodiment. 10 is a graph showing changes over time in the amplitude of light intensity signals output from two light receiving units included in a smoke detector according to an embodiment. FIG. 10 is a diagram illustrating a flow of processing performed by a determination unit according to an embodiment. FIG. 10 is a diagram illustrating a flow of processing performed by a determination unit according to a modified example. 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. FIG. 10 is a diagram showing the functional configuration of a control unit according to a modified example. FIG. 10 is a diagram schematically illustrating the configuration of a smoke detector according to a modified example. FIG. 10 is a diagram schematically illustrating the configuration of a smoke detector according to a modified example. FIG. 10 is a diagram schematically illustrating the configuration of a smoke detector according to a modified example. FIG. 10 is a diagram showing the functional configuration of a control unit according to a modified example.

[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.

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 within the monitored space, detects smoke if it is contained in the air that has been taken in, and, if it detects smoke, notifies the host system 12 of the occurrence of smoke.

In Figure 1, the smoke detection system 1 has one smoke detector 11, but the number of smoke detectors 11 that the smoke detection system 1 has varies depending on the number and size of the monitored spaces.

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 wired, wireless, or a combination of these communication media.

The upper system 12 is similar to the upper system related to conventional technology, so its description will be omitted.

Figure 2 is a schematic diagram showing the configuration of the smoke detector 11. The smoke detector 11 comprises a housing 110, a light emitting unit 111, a lens 112, a light receiving unit 113, a light receiving unit 114, a lens 115, a fan 116, a filter 117, and a control unit 118.

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 entrance 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 exit for air to flow from the internal space to the external space.

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

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 to the exhaust port Q.

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

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 portion of the scattered light, which is a collection of light that is reflected from particles contained in the air that flows from the external space into area A within the sensing area S when light is irradiated from the light emitting unit 111, and outputs a light intensity signal indicating the intensity of the received light to the control unit 118. The light receiving unit 113 is positioned so as not to 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.

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 individual particle that flows into the light irradiated from the light emitting unit 111 from external space and passes through position B within 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 positioned so as not to 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 114.

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 essentially a point.

The fan 116 uses rotating blades to create a flow of air that flows from the external space through the intake port P into the sensing area S and out through the exhaust port Q into the external space.

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

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.

Figure 3 shows the configuration of the computer 10 employed as hardware for the control unit 118. The computer 10 comprises a processor 101 that performs various data processing, a memory 102 that stores various 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).

Figure 4 is a diagram showing the functional configuration of the control unit 118. That is, the computer 10 performs processing in accordance with the program for the control unit 118, thereby realizing the control unit 118 having the components shown in Figure 4. The functional components of the control unit 118 are described below.

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.

The timing means 1184 continuously measures the current time, for example, based on a clock signal generated by a clock provided in the processor 101, and generates a time signal indicating the current time.

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

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.

When the determination means 1186 determines that smoke is present in the external space, the communication means 1187 transmits smoke occurrence notification data to the upper system 12 notifying the occurrence of smoke.

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.

The light intensity signal acquired by the light intensity signal acquisition means 1182 from the light receiving unit 113 indicates the intensity of the total reflected light that reaches the light receiving unit 113 out of the light reflected by multiple particles (particle groups) within an area A of a certain size. Therefore, the amplitude of the light intensity signal acquired by the light intensity signal acquisition means 1182 from the light receiving unit 113 changes continuously in accordance with changes in the concentration of smoke within the sensing area S.

On the other hand, the light intensity signal acquired by the light intensity signal acquisition 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 essentially be considered a point. Therefore, the light intensity signal acquired by the light intensity signal acquisition means 1183 from the light receiving unit 114 is a pulse signal that rises the instant a particle passes position B. Then, as the concentration of smoke within the sensing area S changes, the frequency of occurrence of these pulse signals, i.e., the number of occurrences per given time, changes.

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

Figure 6 is a diagram illustrating the processing flow performed by the determination means 1186. The determination means 1186 performs processing according to the flow shown in Figure 6 every time a sufficiently short predetermined time has elapsed. The processing performed by the determination means 1186 is explained below.

The determination means 1186 first determines whether the light intensity signal acquired by the light intensity signal acquisition means 1182 from the light receiving unit 113 reaches a predetermined threshold value Z (step S101).

In step S101, 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 Z (step S101; No), the judgment means 1186 sets a predetermined value X to the threshold value T used in the judgment in step S104 (step S102).

On the other hand, in step S101, if the light intensity signal acquisition means 1182 determines that the light intensity signal acquired from the light receiving unit 113 has reached the threshold value Z (step S101; Yes), the judgment means 1186 sets the threshold value T used in the judgment in step S104 to a predetermined value Y smaller than the value X (step S103).

Following processing of step S102 or S103, the judgment 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).

In step S104, if it is determined that the number of particles counted by the counting means 1185 has reached the threshold value T (step S104; Yes), the determination means 1186 determines that smoke is occurring in the external space and instructs the communication means 1187 to send 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 determination means 1186. Thereafter, the determination means 1186 terminates the series of processes shown in Figure 6.

On the other hand, if, in step S104, 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 judgment means 1186 determines that no smoke is 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.

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

[Modification]
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.

(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 obtained by the light intensity signal obtaining means 1182 from the light receiving unit 113 (i.e., the measurement value of the light intensity measuring means).

Alternatively, a configuration may be adopted in which the determination means 1186 determines the presence or absence of smoke 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 smoke determination conditions 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).

Figure 7 is a diagram illustrating the processing flow performed by the determination means 1186 in one example of this modified example. The determination means 1186 performs processing according to the flow shown in Figure 7 every time a sufficiently short predetermined time has elapsed. The processing performed by the determination means 1186 shown in Figure 7 is described below.

The determination means 1186 first determines whether the number of grains counted by the counting means 1185 has reached a predetermined threshold Y (step S201).

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).

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

Following 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 has reached the threshold value T whose value was set in step S202 or S203 (step S204).

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

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 judgment 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.

In this modified example, the determination means 1186 determines the presence or absence of smoke in the external space based on the determination condition of whether the intensity of scattered light generated by the particle group in area A, as indicated by the light intensity signal acquired by the light intensity signal acquisition means 1182, has reached a threshold value T. Then, if 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 than when the threshold value T is not changed in this way.

In addition, the smoke detector 11 of this modified example can determine the presence or absence of smoke in the external space with particle sizes that cannot be measured by a particle number measuring means.

For example, if the particle size of the 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 cases, smoke cannot be detected based solely on the number of particles counted by the counting means 1185.

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

(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.

For example, a judgment 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 judgment 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 judgment criterion based on the measurement value of the light intensity measurement means.

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 value 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 value X continues to exceed threshold value 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 value 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 value X continues to exceed threshold value T2, which is smaller than threshold value T1.

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 has reached 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.

For example, a judgment criterion may be adopted that determines that smoke is being generated when the light intensity reaches a predetermined threshold and continues to reach that threshold for a predetermined period of time or longer. In this example, the judgment 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 judgment criterion based on the measurement value of the particle number measurement means.

For example, when the number of particles counted by the counting means 1185 has not reached threshold Y, the determination means 1186 determines that smoke is occurring when the time during which the light intensity signal acquired by the light intensity signal acquisition means 1182 from the light receiving unit 113 has reached threshold W continues to exceed threshold T1. On the other hand, when the number of particles counted by the counting means 1185 has reached threshold Y, the determination means 1186 determines that smoke is occurring when the time during which the light intensity signal acquired by the light intensity signal acquisition means 1182 from the light receiving unit 113 has reached threshold W continues to exceed threshold T2, which is smaller than threshold T1.

(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.

Figure 8(a) is a graph showing the change in light intensity signal over time 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 in light intensity signal over time 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 air flowing through sensing area S is the same.

As shown in Figure 8, the larger the particle size of the particle passing through position B, the wider the width of the pulse appearing in the light intensity signal along the time axis. In general, the larger the particle size of the particle passing through position B, the greater the amplitude of the pulse appearing in the light intensity signal.

Therefore, based on the light intensity signal acquired by the light intensity signal acquisition 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 determined.

When smoke is present in the sensing area S, even if the light intensity indicated by the light intensity signal acquired by the light intensity signal acquisition means 1182 from the light receiving unit 113 is the same, the concentration of the smoke will differ if the particle size of the smoke is different. Generally, when the light intensity indicated by the light intensity signal acquired by the light intensity signal acquisition 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.

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.

Figure 9 is a diagram showing the functional configuration of the control unit 118 provided in the smoke detector 11 according to this modified example. Some of the components shown in Figure 9 are common to the components of the control unit 118 according to the embodiment shown in Figure 4. These components are designated by the same reference numerals as those used in Figure 4. Below, we will explain the components shown in Figure 9 that differ from the components shown in Figure 4.

The particle size calculation means 1188 calculates the particle size of particles passing through position B. Specifically, the particle size calculation means 1188 calculates the particle size of particles passing through position B by multiplying the width (or amplitude) in the time axis direction of the pulse wave that appears in the time-dependent change in 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 the air flowing through the sensing area S. Alternatively, for example, the particle size calculation means 1188 may determine the particle size of particles 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 that calculates 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 a particle size measurement means that measures the particle size of particles contained in the air flowing into the sensing area S from external space.

In addition, if the flow velocity of the air flowing through the sensing area S changes, the smoke detector 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 from the flow meter.

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).

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 smoke concentration that uses particle size and light intensity as variables.

When the concentration of smoke identified as described above reaches a predetermined threshold, the determination means 1189 determines that smoke is occurring in the external space. Note that the determination conditions used by the determination means 1189 to determine the presence or absence of smoke are not limited to this. For example, a determination condition may be adopted that determines that smoke is occurring in the external space when the concentration of smoke identified by the determination means 1189 reaches a predetermined threshold and continues to reach the predetermined threshold for a predetermined period of time or longer.

Furthermore, the determination means 1189 does not necessarily need to identify the concentration of smoke. For example, instead of comparing the concentration of smoke with a threshold, the determination means 1189 may determine the presence or absence of smoke 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 light intensity threshold 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.

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 corrected light intensity measurement value with a threshold value to determine whether smoke is being generated.

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 obtained from the light receiving unit 113 to determine whether or not smoke is present.

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.

When the determination means 1189 detects smoke, the communication means 1190 transmits particle size notification data, which notifies the host system 12 of the particle size calculated by the particle size calculation means 1188, along with the smoke detection notification data. The particle size indicated by the particle size notification data is information indicating the type of smoke (black smoke, white smoke, etc.). For example, a manager or the like who receives notification of smoke generation via the host system 12 can use the particle size notified at the same time to identify the source of the fire and identify appropriate fire extinguishing methods.

(Variation 4)
In the above-described embodiment, the scattered light, which is a collection of light reflected by a particle group 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 emitting unit 111. Alternatively, a configuration may be adopted in which the light receiving unit 113 receives light from a different light emitting source than the light receiving unit 114.

Figure 10 is a diagram showing a schematic configuration of an example of a smoke detector 11 relating to such a modified example. The smoke detector 11 shown in Figure 10 includes a light-emitting unit 111(1) and a light-emitting unit 111(2).

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

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

In addition, compared to the smoke detector 11 of this modified example, the smoke detector 11 of the above-mentioned embodiment requires fewer light-emitting elements, which is desirable in that it can be made smaller and less expensive.

(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.

Figure 11 is a diagram showing a schematic configuration of an example of a smoke detector 11 relating to such a modified example. The housing 110 of the smoke detector 11 shown in Figure 11 has different sensing areas formed therein, sensing area S11 and sensing area S12. Here, different sensing areas refer to areas that are separated so that light emitted in one area does not substantially reach the other area, and do not necessarily have to be completely separated areas. Sensing area S11 includes area A, and sensing area S12 includes position B.

The light-emitting unit 111 provided in the smoke detector 11 shown in Figure 11 is disposed on the boundary between the sensing area S11 and the sensing area S12, and emits light to both the sensing area S11 and the sensing area S12. Note that the light-emitting unit 111 may be configured with two different light-emitting units disposed in each of the sensing areas S11 and S12.

In addition, compared to the smoke detector 11 of this modified example, the smoke detector 11 of the above-described embodiment 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.

(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.

Figure 12 is a diagram showing a schematic configuration of the smoke detector 11 according to this modified example. Figure 13 is a diagram showing the functional configuration of the control unit 118 according to this modified example.

In this modified example, the light receiving unit 114 also serves the role of the light receiving unit 113. Furthermore, in this modified example, the smoke detector 11 includes, in addition to the light emitting unit 111, a light emitting unit 119 that is different from the light emitting unit 111. The light emitting unit 119 irradiates light widely onto an area A that is closer to the light receiving unit 114 than position B.

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

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

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

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 as shown in FIG. 12, smoke detector 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.

(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.

1...Smoke detection system, 10...Computer, 11...Smoke detector, 12...Housing, 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...Time counting 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 (5)

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 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 measurement value of the second light intensity measurement means ;
Equipped with
A smoke detector in which, when the measurement value of the second light intensity measuring means satisfies a predetermined condition, the judgment means changes the conditions for judging whether or not smoke is present based on the measurement value of the first light intensity measuring means so as to detect smoke more quickly . 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 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 measurement value of the second light intensity measurement means ;
Equipped with
A smoke detector in which, when the measurement value of the first light intensity measuring means satisfies a predetermined condition, the judgment means changes the conditions for judging whether or not smoke is present based on the measurement value of the second light intensity measuring means so as to detect smoke more quickly . a light emitting means for emitting light;
3. The smoke detector according to claim 1, wherein 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. 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 smoke detector according to claim 1 , wherein the second light intensity measuring means measures the light intensity using the light receiving element when light is emitted to the predetermined position but not to the predetermined area. The smoke detector according to claim 1 , wherein the sensing area including the predetermined position and the sensing area including the predetermined area are the same area.