JP2008083923A - Fire alarm - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fire alarm to early detect fire at midnight. <P>SOLUTION: The fire alarm, having a fire occurrence detection means 1a for detecting a fire occurrence according to the result of comparing a fire sensor signal from a fire sensor 2 with a fire decision threshold for fire decision, and a fire alarm means 6 for issuing an alarm of the fire occurrence detected by the fire occurrence detection means 1a, is further provided with an ambient temperature detection means 3b, a time zone setting means 1b and a fire decision threshold change means 1c. The ambient temperature detection means 3b detects the one day's ambient temperature at predetermined time intervals. The time zone setting means 1b sets sensitivity change time zones of the predetermined time intervals on the basis of the acquisition time of a temperature detection signal corresponding to the lowest temperature out of one day's ambient temperature detection signals detected by the ambient temperature detection means 3b. The fire decision threshold change means 1c changes the fire decision threshold to a fire decision threshold for higher sensitivity in the sensitivity change time zones set by the time zone setting means 1b. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fire alarm device, and more particularly to a fire alarm device for early detection of a fire.

  In recent years, house fires have been increasing. In particular, there are many late night hours by time, and bedrooms and kitchens are often used as fire places by location. Therefore, recently, the Fire Prevention Ordinance has been amended to require the installation of fire alarms for homes in ordinary houses, and installation in all bedrooms (if the bedroom is on the second floor is also on the stairs) and kitchen is required. ing.

  Fire alarms need to respond more quickly in the event of a fire, and for that purpose, an effective method has been proposed in which a smoke-type fire alarm is used for early detection. In addition, as mentioned above, the installation of bedrooms, stairs, etc. is particularly obligatory, and measures are taken to detect and alarm fires especially at bedtime. The problem is how early fire can be detected.

Conventionally, there has been proposed a fire alarm that can switch an alarm level between daytime and nighttime (see, for example, Patent Document 1).
JP-A-6-314384 (paragraph [0003])

  However, although there is disclosure that the alarm level can be switched between daytime and nighttime in the above-described fire alarm device, it is specifically disclosed whether or not it leads to early detection particularly in the late-night time zone. Not.

  Then, in view of the subject mentioned above, this invention aims at providing the fire alarm which aims at the early detection of the fire in the midnight time slot | zone.

  The invention according to claim 1 made to solve the above-mentioned problem is based on a comparison result between a fire sensor signal from the fire sensor 2 and a fire judgment threshold value for judging a fire, as shown in the basic configuration diagram of FIG. A fire alarm device having a fire occurrence detection means 1a for detecting the occurrence of a fire and a fire alarm means 6 for alarming the occurrence of a fire detected by the fire occurrence detection means 1a. The ambient temperature detection means 3b that detects at intervals and the acquisition time of the temperature detection signal corresponding to the lowest temperature of the ambient temperature detection signals detected by the ambient temperature detection means 3b for a predetermined time interval. A fire determination for changing the fire determination threshold to a high sensitivity fire determination threshold during the time zone setting means 1b for setting a sensitivity change time zone and the sensitivity change time zone set by the time zone setting means 1b. Characterized in that it further comprises a value change means 1c, and.

  In the first aspect of the invention, the fire occurrence detection means 1a for detecting the occurrence of fire based on the comparison result between the fire sensor signal from the fire sensor 2 and the fire determination threshold value for judging the fire, and the fire occurrence detection means A fire alarm device having a fire alarm means 6 for alarming the occurrence of a fire detected by 1a, further comprising an ambient temperature detection means 3b, a time zone setting means 1b, and a fire determination threshold value changing means 1c. The ambient temperature detection means 3b detects the ambient temperature for one day at a predetermined time interval. The time zone setting means 1b sets a sensitivity change time zone at a predetermined time interval based on the acquisition time of the temperature detection signal corresponding to the lowest temperature among the ambient temperature detection signals for one day detected by the ambient temperature detection means 3b. Set. The fire determination threshold value changing unit 1c changes the fire determination threshold value to a high sensitivity fire determination threshold value during the sensitivity change time period set by the time period setting unit 1b. As a result, the fire detection threshold is changed to the high sensitivity threshold during the sensitivity change time period of the predetermined time interval, specifically during the midnight time period, and the fire detection sensitivity is increased, so that the fire is accelerated. Can be detected. Moreover, since the sensitivity change time zone is updated every day according to the change in the ambient temperature, it is possible to change the fire determination threshold adapted to the seasonal change.

  In order to solve the above-mentioned problem, the invention according to claim 2 is the fire alarm device according to claim 1, wherein the difference between the ambient temperatures detected by the ambient temperature detecting means 3b during the sensitivity change time zone. Is greater than or equal to a preset temperature difference determination threshold, and when it is determined that the difference in ambient temperature is greater than or equal to a preset temperature difference determination threshold, the fire determination threshold change means 1c It further has a prohibiting means 1d for prohibiting the change.

  In the second aspect of the present invention, the apparatus further includes a prohibiting unit 1d, and whether the difference between the ambient temperatures detected by the ambient temperature detecting unit 3b during the sensitivity change time period is equal to or greater than a preset temperature difference determination threshold value. If it is determined that the difference in ambient temperature is greater than or equal to a preset temperature difference determination threshold, the fire determination threshold changing unit 1c is prohibited from changing the fire determination threshold. Thereby, malfunctions in the sensitivity change time zone can be reduced.

  In order to solve the above-mentioned problem, the invention according to claim 3 is the fire alarm device according to claim 1 or 2, wherein the ambient temperature detection detecting means 3 is a gas sensor, and the gas sensor detects a change in ambient temperature. The gas sensor output when driven to react is used as the ambient temperature detection signal.

  In the third aspect of the invention, the ambient temperature detection detecting means 3 is a gas sensor, and the gas sensor output when the gas sensor is driven so as to react to a change in the ambient temperature is the ambient temperature detection signal. As a result, in the combined fire alarm provided with the gas sensor, it is not necessary to provide a temperature sensor dedicated to ambient temperature detection, and it is possible to detect fire early without increasing the cost.

  According to the first aspect of the present invention, the fire determination threshold is changed to the high sensitivity threshold during the sensitivity change time zone of a predetermined time interval, specifically during the midnight time zone, and the fire detection sensitivity is high. Therefore, fire can be detected early. In addition, since the setting of the midnight time zone is updated every day, it is possible to change the fire determination threshold value adapted to seasonal variations.

  According to the second aspect of the present invention, it is possible to reduce malfunctions in the sensitivity change time zone.

  According to the third aspect of the present invention, in the combined fire alarm provided with the gas sensor, it is not necessary to provide a temperature sensor dedicated to ambient temperature detection, and it is possible to detect fire early without increasing the cost.

  Hereinafter, embodiments of a fire alarm according to the present invention will be described with reference to the drawings. In this embodiment, a composite fire alarm device to which the fire alarm device of the present invention is applied will be described as a configuration example.

  FIG. 2 is a block diagram showing the configuration of the composite fire alarm. The combined fire alarm 10 includes a control unit 1, a fire sensor 2, a gas sensor 3, a sensor drive circuit unit 4, a storage unit 5, an alarm output unit 6, and an external output unit 7. . Although not shown, the composite fire alarm 10 is composed of a casing formed in a substantially box shape with a synthetic resin or the like, and is provided on the back side of the casing at an appropriate installation location (for example, a kitchen) in a general home. It is fixed via a fixing member. The composite fire alarm is operated by electric power supplied from a power supply unit (not shown) including a commercial power supply.

  The control unit 1 is composed of, for example, a microcomputer including a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (A Read / Write Memory as needed). The CPU executes various processes including control according to the present embodiment in accordance with a control program stored in the ROM. The RAM appropriately stores data, programs, and the like necessary for the CPU to execute various processes.

  Based on the fire sensor signal output from the fire sensor 2, the control unit 1 detects a fire detection signal whose value increases as the degree of fire increases, for example, a light extinction rate, a temperature rise rate, a temperature or a CO concentration described later. Is generated. These depend on the type of sensor employed as the fire sensor 2.

  The control unit 1 compares the value of the fire detection signal with a fire determination threshold value for determining a fire, and when the value of the fire detection signal exceeds the fire determination threshold value, an alarm signal indicating the occurrence of a fire Is generated. In response to this alarm signal, a command is given to warn the fire.

  The control unit 1 generates a gas detection signal that increases as the gas concentration increases, based on the gas sensor signal output from the gas sensor 3. These depend on the type of sensor employed as the gas sensor 3.

  Further, the control unit 1 compares the value of the gas detection signal with a gas leakage determination threshold for determining gas leakage, and when the value of the gas detection signal exceeds the gas leakage determination threshold, gas leakage occurs. An alarm signal indicating is generated. In response to this alarm signal, a command is given to warn of gas leakage.

  The fire sensor 2 is, for example, a known smoke sensor, temperature sensor, or CO sensor that outputs a fire sensor signal in response to an event that occurs with a fire. The smoke sensor includes a photoelectric element that outputs a light amount signal corresponding to a light amount on a predetermined optical path. The temperature sensor includes a thermistor whose resistance value varies depending on the ambient temperature, and outputs a temperature signal corresponding to the ambient temperature based on this resistance value. The CO sensor includes a detection element that reduces the internal resistance value when the CO gas is adsorbed, and outputs a concentration signal corresponding to the CO gas concentration based on the internal resistance value. However, each sensor does not need to stick to the above-described principle as long as smoke, temperature, and CO that are detection targets can be accurately measured.

  The gas sensor 3 is a semiconductor gas sensor having a sensor element 3a and a temperature sensor 3b for temperature compensation, and outputs a gas sensor signal indicating a gas concentration detected by a change in resistance value of the sensor element 3a. In this embodiment, the gas sensor 3 is driven so that the element temperature becomes 400 ° C. when methane is detected.

  The control unit 1 generates a gas detection signal indicating the gas concentration from the gas sensor signal of the gas sensor 3. Moreover, the fluctuation | variation state of the ambient temperature in the installation place of the composite fire alarm device 10 of a general household for 24 hours (1 day) is acquired from the temperature sensor 3b for temperature compensation. The control unit 1 has a clock function for knowing the passage of time of 24 hours (one day). The temperature sensor 3b corresponds to the ambient temperature detection means in the claims.

  That is, the fluctuation state of the ambient temperature in one day as shown in FIG. 3 is obtained. In FIG. 3, the vertical axis indicates the gas sensor output (V), and the horizontal axis indicates time (h).

  As shown in FIG. 3, based on the acquisition time of the ambient temperature, the life pattern of the user of the combined fire alarm 10 is roughly grasped from the temperature rise at the time of boiling water, breakfast, lunch and dinner. Can do. In particular, when cooking at the time of breakfast, dinner, etc., the ambient temperature exhibits a characteristic that fluctuates up and down frequently and irregularly, and after that, it changes so as to decrease in a natural logarithm.

  The sensor drive circuit unit 4 is a circuit that is commanded by the control unit 1 and drives the fire sensor 2 and the gas sensor 3 intermittently at predetermined intervals.

  The storage unit 5 is composed of, for example, an EEPROM (Electrically Erasable and Programmable ROM) and stores a normal fire determination threshold C and a high sensitivity fire determination threshold T set in advance.

  In this embodiment, the temperature detection signal of the temperature sensor 3b is acquired by sampling once every hour, for example, and within a predetermined range set with reference to the acquisition time when the temperature becomes the lowest among them, for example. In the midnight time zone, increase the sensitivity of the fire judgment threshold during fire judgment processing (make it easy to sound an alarm).

  For example, when a temperature sensor is employed as the fire sensor 2, the high sensitivity fire determination threshold H is set to 55 ° C. lower than the normal fire determination threshold 60 ° C., and smoke is used as the fire sensor 2. When the sensor is employed, the high-sensitivity fire determination threshold H is set to 7.5% lower than the normal fire determination threshold dimming rate of 10%. The same setting can be made for an ionization fire sensor and other types of fire sensors.

  The temperature detection signal of the temperature sensor 3b is acquired every day, and the minimum (MIN) value of the day is investigated based on the sampling result of 24 times (24 hours). Based on this MIN value, the fire is detected. Set the midnight time zone to increase the sensitivity of the judgment threshold. By doing in this way, even if the shift of the midnight time zone etc. generate | occur | produces by four seasons, the midnight time zone which improves sensitivity can be set reliably. Further, once the power is reset, the composite fire alarm 10 enters an initial state and acquires data for one day. Thereafter, the fire judgment threshold value in the late-night time zone is increased based on the data.

  In addition, in the case of a home that operates at midnight, there may be a case where the temperature does not change gradually as shown in FIG. Similarly, in the case of summer, cooling or the like is used during the midnight hours, and the ambient temperature may be opposite to that in winter, but may not show a gradual temperature change. And if the ambient temperature fluctuates frequently due to heating or cooling during the midnight hours, it may lead to malfunction of the fire alarm. And

  The alarm output unit 6 responds to an alarm signal output from the control unit 1 and outputs a sound alarm, an alarm sound message such as a buzzer or a speech processor for outputting a fire alarm, and a warning display. It is a display output circuit such as LED or LCD to be performed. The alarm output unit 6 corresponds to fire alarm means in the claims. In response to the alarm signal output from the control unit 1, the external output unit 7 is configured to include a communication circuit that sends a message indicating that to an external system, a security center, or the like.

  Note that a power supply circuit, an interface circuit, a display circuit, and the like provided in this type of composite fire alarm 10 are not essential for understanding the present invention and are omitted here.

  Next, an example of the fire determination process of the present invention executed by the control unit 1 of the composite fire alarm 10 having the above configuration will be described with reference to the flowchart of FIG.

  First, the power source of the composite fire alarm device 10 is turned on (step S1), and then measurement of the ambient temperature, that is, the temperature of the room where the composite fire alarm device 10 is installed is started (step S2). Next, the ambient temperature is measured every hour by detecting a temperature detection signal corresponding to a change in ambient temperature from the temperature sensor 3b for temperature compensation of the gas sensor 3 (step S3). This hourly temperature measurement is performed, for example, by measuring six times at one sampling, deleting the maximum and minimum values, and using the average of the remaining four measurement data as the final surroundings for the measurement time. Determined as a temperature measurement.

  Next, measurement data of ambient temperature for 24 hours (one day) is collected (step S4), and then the sensitivity change time for increasing the sensitivity of the fire determination threshold based on the collected measurement data of ambient temperature A zone, specifically, a midnight time zone is calculated (step S5). This midnight time zone is set by calculating a time zone from the acquisition time of the lowest value of the ambient temperature to a time that is a predetermined time later, based on the MIN value of the ambient temperature collected for 24 hours. As an example, the midnight time zone is set as (minimum acquisition time of ambient temperature-2 hours) to (minimum acquisition time of ambient temperature-2 hours + 6 hours).

  For example, after turning on the composite fire alarm 10 at 10:00 am, the ambient temperature for 24 hours is measured every hour. As a result of measurement, when the MIN value of the ambient temperature is, for example, 4 hours before power-on (6 am) as shown in FIG. 3, the midnight time zone Tt is 6 hours before power-on (4 am ) To 12 hours before (10:00 pm). And the midnight time zone calculated in this way is set as 6 hours starting from 13 hours (10 pm) after the time when the midnight time zone was calculated (10 am) based on the measurement result of the ambient temperature for 24 hours. Is done. The remaining 18 hours of the 24 hours other than the midnight time zone is the normal time zone Tc.

  Next, it is determined whether or not the current time is in the midnight time zone based on the clock function (step S9). If it is not the midnight time zone (No in step S9), then the fire sensor signal of the fire sensor 2 is monitored (step S6), and then the presence or absence of a fire is determined (step S7). This determination is performed by monitoring the fire sensor signal of the fire sensor 2 and comparing the fire detection signal generated from the fire sensor signal with the normal fire determination threshold C stored in the storage unit 5 in advance. If the signal exceeds the fire determination threshold C, it is determined that there is a fire, and if the fire detection signal does not exceed the fire determination threshold C, it is determined that there is no fire. If it is determined that there is no fire (No in step S7), then the process returns to step S6. If it is determined that there is a fire (Yes in step S7), then an alarm signal is generated and output to the alarm output unit 6. The output unit 6 issues an alarm by sounding an alarm sound or displaying an alarm (step S8). Moreover, the external output part 7 sends out the message | telegram which shows a fire outbreak to an external system, a security center, etc. as needed.

  On the other hand, if the current time is in the midnight time zone (Yes in step S9), then the fire determination threshold value is set to the high sensitivity fire determination threshold value T stored in advance in the storage unit 5 from the normal fire determination threshold value C. (Step S10). Next, the fire sensor signal of the fire sensor 2 is monitored (step S11), and then the presence or absence of a fire is determined (step S12). This determination is performed by monitoring the fire sensor signal of the fire sensor 2 and comparing the fire detection signal generated from the fire sensor signal with the high-sensitivity fire determination threshold T changed from the normal fire determination threshold C. If the fire detection signal exceeds the high sensitivity fire determination threshold T, it is determined that there is a fire. If the fire detection signal does not exceed the fire determination threshold T, it is determined that there is no fire. If it is determined that there is no fire (No in step S12), then the process returns to step S11, and if it is determined that there is a fire (Yes in step S12), then an alarm signal is generated and output to the alarm output unit 6, The output unit 6 issues an alarm by sounding an alarm sound or displaying an alarm (step S13). Moreover, the external output part 7 sends out the message | telegram which shows a fire outbreak to an external system, a security center, etc. as needed.

  As is clear from the above description, the control unit 1 functions as the fire occurrence detection means 1a, the time zone setting means 1b, and the fire determination threshold value changing means 1c in the claims. Step S5 in the flowchart of FIG. The process corresponds to the setting means 1b, step S10 is a process corresponding to the fire determination threshold value changing means, and steps S7 and S12 are processes corresponding to the fire occurrence detection means 1a.

  Thus, according to the present invention, the fire detection threshold is changed to the high sensitivity threshold during the sensitivity change time zone of a predetermined time interval, specifically, during the midnight time zone, and the fire detection sensitivity is high. Therefore, fire can be detected early. Moreover, since the sensitivity change time zone is updated every day according to the change in the ambient temperature, it is possible to change the fire determination threshold adapted to the seasonal change. Further, since the gas sensor is also used as a temperature sensor for detecting the ambient temperature, it is not necessary to provide a temperature sensor dedicated to detecting the ambient temperature, and it is possible to detect a fire early without increasing the cost.

  As described above, the embodiment of the present invention has been described. However, the present invention is not limited to this, and various modifications and applications are possible.

  For example, in the above-described embodiment, the ambient temperature is measured every hour. However, the measurement is not limited to this, and can be performed at other time intervals such as minutes. In the above-described embodiment, the sensitivity change time zone (midnight time zone) is a time having a 6-hour time interval from 2 hours to 8 hours before, based on the measurement time of the measured MIN value of the ambient temperature. However, the present invention is not limited to this, and it is also possible to appropriately set a time zone having other time intervals, start and end times, etc. with reference to the measurement time of the MIN value of the ambient temperature.

  Further, in the above-described embodiment, the fire determination threshold value in the set midnight time zone is changed from the normal fire determination threshold value C to the high-sensitivity fire determination threshold value T. It is determined whether or not the difference between the measured values of each ambient temperature measured in the midnight time zone is greater than or equal to a preset temperature difference determination threshold stored in the storage unit 5. You may comprise so that the change of a determination threshold value is prohibited. In this case, the control unit 1 corresponds to a prohibition unit in the claims.

  Further, in the above-described embodiment, after changing the fire determination threshold value in the set midnight time zone from the normal fire determination threshold value C to the high sensitivity fire determination threshold value T, the control unit 1 sends an alarm signal to the alarm output unit 6. The alarm output unit 6 issues an alarm such as an alarm sound, an alarm voice message, and an alarm display. Instead, after changing to the fire detection threshold T for high sensitivity, the control unit 1 generates an alarm signal. A different preliminary alarm signal is output to the alarm output unit 6 so that a preliminary alarm such as an alarm sound, an alarm voice message, an alarm display or the like different from that at the time of the alarm signal input can be emitted from the alarm output unit 6. good.

  In the above-described embodiment, the temperature compensation temperature sensor 3b built in the gas sensor 3 is used as the ambient temperature detection temperature sensor. However, the temperature sensor 3b is not limited to this, and the temperature variation of the heat detection fire thermistor and gas sensor. Other temperature sensors can also be used.

  Furthermore, the heater resistance of the gas sensor or the gas sensor itself can be used as the temperature sensor for detecting the ambient temperature.

For example, as shown in FIG. 5, the semiconductor gas sensor 30 includes a gas sensitive body (SnO ₂ sintered body) 1a, a heater coil 30b, heater electrodes 30b1, 30b2, and a sensor electrode 30c. The material of the heater coil 30b uses a Pt (platinum) wire, and this Pt wire has a temperature coefficient of 3927 ppm / K in the temperature range of 0 to 100 ° C. with respect to the ambient temperature. Therefore, a voltage that does not reach a very high temperature is applied to the heater coil 30b in a pulsed manner separately from the gas detection area (if the temperature is higher than 100 ° C., it becomes difficult to detect the ambient temperature. ), And the resistance change of the Pt line at that time can be electrically measured to obtain temperature information.

  Also, in the case of the contact combustion type gas sensor, the Pt line is used as the heater material, and the temperature rise is detected as a change in resistance of the Pt line by contact combustion with the combustible gas, so that the combustible gas causes contact combustion. If the temperature is lowered to a level that is not present (for example, 80 ° C. or lower), the ambient temperature can be measured as in the case of the semiconductor gas sensor. In this case, since the resistance change of the Pt line of the catalytic combustion type gas sensor is originally taken out as a sensor output, the sensor output of the gas sensor itself is used as a temperature detection signal of the ambient temperature. When driven to react to changes in ambient temperature other than when detecting gas, it also serves as ambient temperature detection means.

It is a basic composition figure showing the basic composition of the fire alarm of the present invention. It is a block diagram which shows the structure of the composite-type fire alarm to which the alarm device which concerns on this invention is applied. It is a graph which shows the gas sensor output characteristic with respect to time reflecting the fluctuation | variation of ambient temperature in the composite-type fire alarm of FIG. It is a flowchart which shows the fire determination process which the control part in the composite fire alarm of FIG. 2 performs. It is a figure which shows the structural example of a semiconductor type gas sensor.

Explanation of symbols

1 Control unit 1a Fire occurrence detection means (control unit)
1b Time zone setting means (control unit)
1c Fire determination threshold value changing means (control unit)
1d Prohibition means (control unit)
2 Fire sensor 3b Ambient temperature detection means (temperature sensor)
6 Fire alarm means (alarm output part)
10 Combined fire alarm

Claims (3)

A fire occurrence detection means for detecting the occurrence of a fire based on a comparison result between a fire sensor signal from the fire sensor and a fire judgment threshold value for judging a fire; and a fire alarm means for alarming a fire occurrence detected by the fire occurrence detection means; A fire alarm having
Ambient temperature detection means for detecting the ambient temperature for one day at predetermined time intervals;
A time zone setting means for setting a sensitivity change time zone at a predetermined time interval based on an acquisition time of a temperature detection signal corresponding to the lowest temperature among the ambient temperature detection signals for one day detected by the ambient temperature detection means; ,
During the sensitivity change time zone set by the time zone setting means, a fire judgment threshold value changing means for changing the fire judgment threshold value to a fire judgment threshold value for high sensitivity,
A fire alarm further comprising: The fire alarm according to claim 1,
It is determined whether or not the difference between the ambient temperatures detected by the ambient temperature detection means during the sensitivity change time period is equal to or greater than a preset temperature difference determination threshold, and the difference between the ambient temperatures is a preset temperature. A fire alarm device further comprising prohibition means for prohibiting the change of the fire determination threshold value by the fire determination threshold value changing means when it is determined that the difference determination threshold value is exceeded. The fire alarm according to claim 1 or 2,
The ambient temperature detection means is a gas sensor, and a gas alarm output when the gas sensor is driven to react to a change in ambient temperature is used as the ambient temperature detection signal.

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