JP5882802B2 - Flame monitoring device - Google Patents

Description

The present invention relates to a flame monitoring device that detects and alerts to ultraviolet rays emitted from a flame.

  2. Description of the Related Art Conventionally, there is known a flame monitoring device that detects ultraviolet rays emitted from a flame and gives an alarm, and is used as an arson sensor or a flame detector.

Such a flame monitoring apparatus uses an ultraviolet detection tube as a flame detection unit. In the UV detector tube, an anode and a cathode are placed in a glass tube that transmits UV rays, and a special gas is sealed. A high voltage is applied between the anode and the cathode in a pulsed manner, and radiation is emitted from the flame in this state. When ultraviolet rays of 185 to 260 nanometers having a specific wavelength band are incident, an avalanche discharge is caused by emission of photoelectrons. The discharge of this ultraviolet ray detection tube is electrically taken out as an ultraviolet ray detection pulse signal, the number of discharges per unit time is counted, and this count value is regarded as the amount of ultraviolet ray and detected. When the amount of ultraviolet rays detected in this way exceeds a predetermined threshold, a flame is determined, and a flame determination signal is transmitted to an alarm device or a receiver to give an alarm. As such an ultraviolet detection tube, for example, a commercially available product as UV TRON (R) can be used.

JP-A-6-325269 JP-A-3-174699 JP-A-6-290375 JP 2009-119165 A

  By the way, the ultraviolet ray detection tube provided in the flame monitoring device causes a self-discharge in a state where a high voltage is applied even if ultraviolet rays are not incident due to manufacturing variations or the like, which causes a false alarm.

  Further, when the period of use of the flame monitoring device becomes longer, the number of self-discharges tends to increase due to deterioration of the ultraviolet detection tube, which also contributes to false alarms.

  In addition, the ultraviolet detector tube causes discharge due to factors in the natural world other than ultraviolet rays generated from the flame. These factors include sunlight, welding light, plasma, radiation, and cosmic rays. Although sunlight is generally considered not to cause discharge, it may cause discharge when it receives light due to reflection or the like. Cosmic rays come from outer space and pass through the UV detector tube at a certain frequency, causing discharge. The discharge of the UV detector tube due to such natural factors is unavoidable as background noise, and is a cause of false alarms.

  The flame monitoring device adjusts the detection sensitivity according to the flame to be monitored. Here, the flame detection sensitivity means a detection performance indicating a limit (lower limit) of a flame size that can be detected using an ultraviolet ray detection tube.

  For example, when a flame monitoring device is used as an arson sensor, the detection sensitivity is set high by lowering the flame determination threshold in order to determine and warn a minute flame such as a writer.

  In addition, when a flame monitoring device is installed in a building and used as a flame detector, the flame detection threshold is increased and detection sensitivity is lowered to prevent false alarms by detecting the writer's flame associated with smoking. It is set.

  However, if the detection sensitivity of the flame monitoring device is set low in order to prevent false alarms associated with smoking, there are people going in and out, and it can be said that it is an appropriate setting sensitivity in the daytime hours when smoking is performed, In a time zone such as at night when the person is unattended, for example, a flame cannot be detected when an intruder tries to ignite with a writer, and the sensitivity cannot be set appropriately.

  In order to solve this problem, for example, during the daytime when smoking is performed, the detection sensitivity of the flame monitoring device is changed to a low sensitivity so that the writer's flame due to smoking is not detected. In the time zone, a method of changing the detection sensitivity of the flame monitoring device to a high sensitivity so that the flame of the writer due to arson can be detected can be considered.

  A conventional flame monitoring device detects an ultraviolet ray amount (count value) by counting an ultraviolet ray detection pulse signal generated by discharge of an ultraviolet ray detection tube when ultraviolet ray is incident over a predetermined time, and the detected ultraviolet ray amount is a predetermined threshold value. The flame is judged when exceeding the value, and the change of the detection sensitivity changes the threshold value of the flame judgment.

  However, as described above, the amount of ultraviolet rays detected by the discharge of the ultraviolet detector tube includes the amount of noise such as self-discharge and discharge due to background noise, and the amount of ultraviolet rays detected to increase detection sensitivity. When the threshold value for flame determination is reduced, there is a possibility that a false alarm is generated due to the influence of the noise amount, and there is a problem that the detection sensitivity cannot be changed to a detection sensitivity suitable for the flame to be determined.

  In particular, in order to detect a small flame with a short duration that emits ultraviolet rays, such as a writer's flame, it is necessary to make the flame judgment threshold relative to the ultraviolet detection amount quite small. However, there is a possibility that false alarms frequently occur due to self-discharge or discharge due to background noise.

The present invention can be used as a determination target or non-determination target flame without being affected by discharge due to self-discharge or background noise even for a short flame that emits ultraviolet rays, such as a writer flame. An object of the present invention is to provide a flame monitoring device that can be changed to a suitable detection sensitivity.

(Basic configuration)
The present invention provides a flame monitoring apparatus,
An oscillation unit that generates a synchronization pulse signal every predetermined period (T2) and outputs a predetermined high voltage in synchronization with the synchronization pulse signal;
An ultraviolet ray detector that includes an ultraviolet ray detector tube and outputs an ultraviolet ray detection pulse signal by a discharge operation of the ultraviolet ray detector tube when ultraviolet rays are incident from the outside in a high voltage application state;
A flame determination unit that determines a flame and outputs a flame determination signal when the number of continuous outputs (number of continuous discharges) of the ultraviolet detection pulse signal matches a predetermined flame determination threshold (Nth) ;
A sensitivity changing unit for changing the flame detection threshold of the flame determining unit to change the flame detection sensitivity;
Is provided.
Is provided.

(Change of flame judgment threshold and detection sensitivity)
Here, the oscillation unit has a period ( T1 / Nth) obtained by dividing a predetermined flame continuation time (T1) in which ultraviolet rays from a flame to be monitored continuously enter by a predetermined flame determination threshold (Nth) ( T2)
Sensitivity changing unit, when a higher detection sensitivity by changing the flame determination threshold to a small value, when to lower the detection sensitivity changes the flame determination threshold value to a large value.

(Sensitivity change by time zone)
The sensitivity changing unit divides the day into a plurality of time zones, sets different flame determination threshold values for the plurality of time zones, and changes the detection sensitivity.
In addition, the sensitivity changing unit divides the day into a predetermined first time zone in which the person is unattended and a predetermined second time zone in which the person goes in and out, and the first time zone is high by setting a predetermined first flame determination threshold value. change in the detection sensitivity, the second time zone is changed to lower the detection sensitivity by setting the second flame determination threshold larger than the first flame determination threshold value.

(Sensitivity change by human sensor)
The sensitivity changing unit includes a human sensor for detecting a person. When a human is detected by the human sensor, a predetermined first flame determination threshold is set and the detection sensor is changed to a high detection sensitivity, and the human is detected by the human sensor. If not, a predetermined second flame determination threshold value greater than the first flame determination threshold value is set and changed to a low detection sensitivity.
Moreover, a sensitivity change part will change to the flame determination threshold value corresponding to, after predetermined | prescribed delay time passes from the said change, when the human detection state by a human sensitive sensor changes.

(Change in sensitivity to false alarms)
Sensitivity changing unit is in a normal monitoring state is changed to the high detection sensitivity by setting a predetermined first flame determination threshold, the first flame determination threshold value greater than the second flame determination threshold when receiving a false alarm corresponding operation Set to change to low detection sensitivity.
In addition, when the sensitivity changing unit receives an operation for handling false alarms and sets the second flame determination threshold value to change to a low detection sensitivity, the sensitivity change unit sets the first flame determination threshold value after a predetermined time and restores the high detection sensitivity.

(Basic effect)
According to the present invention, a continuous UV detection pulse signal outputted by discharging operation when the UV detection tube is applied with a high voltage synchronized with the synchronization pulse signal every predetermined period (T2) and ultraviolet rays are incident from the outside. When the output number (N) matches a predetermined flame determination threshold value (Nth), the flame is determined and a flame determination signal is output, and the flame detection threshold value (Nth) is changed to change the flame detection sensitivity. Therefore, it is possible to appropriately set and change the flame detection sensitivity without being affected by the self-discharge due to the characteristics or deterioration of the ultraviolet detection tube or the noise discharge due to the background noise caused by the factors of the natural world. .

That is, the self-discharge due to the characteristics and deterioration of the UV detector tube, or the noise discharge due to background noise caused by natural factors, is a single discharge and does not result in a continuous discharge as in the case where UV light from a flame is incident. In many cases, the number of continuous outputs of the ultraviolet detection pulse signal by self-discharge or noise discharge does not reach the flame determination threshold (Nth). For this reason, the flame determination threshold for determining the flame from the number of continuous outputs of the ultraviolet ray detection tube (the number of continuous discharges) is set according to the size of the flame to be determined or not to be determined, Moreover, by changing, it is possible to accurately and appropriately set and change the flame detection sensitivity without being affected by self-discharge or noise discharge. The magnitude of the flame corresponds to the flame duration of a flame that emits ultraviolet rays of a predetermined level or higher.

(Effect of changing detection sensitivity according to flame judgment threshold)
In addition, when the flame detection sensitivity is increased, the flame determination threshold is changed to a smaller value, and when the flame detection sensitivity is decreased, the flame determination value is changed to a larger value. The detection sensitivity to flames can be easily changed.

(Effect of changing detection sensitivity according to time zone)
Further, the day is divided into a plurality of time zones, for example, a predetermined first time zone in which the day is unattended and a predetermined second time zone in which a person enters and exits. The first time zone has a predetermined first flame determination threshold value. By setting and changing to a high detection sensitivity, and setting a predetermined second flame determination threshold value that is larger than the first flame determination value and changing to a low detection sensitivity in the second time zone, for example, the first time at night when the person is unattended The time zone can be changed to high sensitivity, and the writer's flame due to arson can be judged and alarmed reliably, and the second time zone where people enter and exit is changed to low sensitivity and the false alarm due to the writer's flame accompanying smoking Can be prevented.

(Sensitivity change by human sensor)
In addition, when a person is detected by a human sensor, a predetermined first flame determination threshold is set and changed to a high detection sensitivity, and when a human is not detected by a human sensor, it is larger than the first flame determination value. Since the second flame judgment threshold is set and changed to a low detection sensitivity, for example, in the case of flame monitoring for arson, if a person is detected, the detection sensitivity is increased and the writer tries to ignite the fire. It is possible to prevent false alarm by changing the detection sensitivity to a low detection sensitivity when the flame is surely determined and a person is not detected.

(Effect of sensitivity change for false alarm)
In a normal monitoring state, when a predetermined first flame determination threshold is set and the detection sensitivity is changed to a high detection sensitivity and a false alarm is determined, for example, a predetermined second larger than the first flame determination value by an operation for handling a false alarm by a person in charge or the like. By setting a flame judgment threshold and temporarily changing it to a low detection sensitivity, for example, if the cause of a false alarm due to a flame other than a fire is known, the cause of the false alarm can be resolved without stopping the monitoring function. The detection sensitivity can be temporarily lowered until the false alarm can be prevented or suppressed.

The block diagram which showed embodiment of the flame monitoring apparatus for arson monitoring which changes detection sensitivity according to a time slot | zone Explanatory drawing which showed discharge operation of the ultraviolet ray detection tube when changing the ultraviolet ray incidence of the flame to be monitored and the flame judgment threshold Time chart showing the operation of the flame monitoring device of FIG. Explanatory drawing which showed the relationship between the flame continuation time of the flame to be monitored and the discharge operation of the ultraviolet ray detector tube when the flame judgment threshold is changed by the sensitivity change instruction Explanatory diagram showing a list of relationships between flame duration, synchronization pulse signal period, and detection sensitivity when changing the flame judgment threshold according to the sensitivity change instruction The flowchart which showed the processing operation in the case of implement | achieving the flame determination and sensitivity change of FIG. 1 by execution of the program of a computer circuit The block diagram which showed other embodiment of the flame monitoring apparatus used as a flame detector

[Configuration of flame monitoring device]
(overall structure)
FIG. 1 is a block diagram showing an embodiment of a flame monitoring apparatus according to the present invention, taking as an example a case where flame is monitored as an arson sensor.

  In FIG. 1, the flame monitoring apparatus of the present invention includes an oscillation unit 10, an ultraviolet ray detection unit 12, a flame determination unit 14, a sensitivity change unit 16, a battery power source 18, and a wireless communication unit 20.

  The battery power source 18 uses, for example, a lithium battery and operates by supplying, for example, DC 5V to each unit.

(Configuration of Oscillator 10)
The oscillation unit 10 includes an oscillation circuit 22 and a high voltage generation circuit 24. The oscillating unit 10 generates a synchronous pulse signal a having a pulse width of, for example, several microseconds at a predetermined period T2, and outputs it to the high voltage generation circuit 24. The high voltage generation circuit 24 uses a booster circuit or the like, and outputs a high voltage set in a range of 300 to 500 V in synchronization with the synchronization pulse signal a to the ultraviolet detection unit 12 in a pulsed manner. The synchronization pulse signal a from the oscillation circuit 22 is also supplied to the flame determination unit 14 for operation, but is not shown.

(Configuration of UV detector 12)
The ultraviolet detection unit 12 includes an ultraviolet detection tube 26. The ultraviolet detection tube 26 has an anode and a cathode disposed in a glass tube that transmits ultraviolet rays and encloses a special gas. For example, a commercially available UVtron (R) is used. The output of the high voltage generation circuit 24 is connected to the anode terminal of the ultraviolet ray detection tube 26 via the resistor R1, the resistor R2 and the capacitor C are connected in parallel to the cathode terminal, and a flame determination unit is interposed between the cathode terminal and the resistor R2. 14 is connected to output an ultraviolet detection pulse signal b.

  The ultraviolet ray detection tube 26 causes discharge when ultraviolet light having an intensity exceeding a predetermined discharge start level is incident from the outside in a state where a high voltage is applied in a pulse manner in synchronization with the synchronization pulse signal a from the oscillation unit 10 A discharge current is caused to flow in a pulse manner through the path of R1, the ultraviolet ray detection tube 26, and the resistor R2, and the ultraviolet ray detection pulse signal b generated at both ends of the resistor R2 is output to the flame determination unit 14.

  The ultraviolet ray detection tube 26 may cause self-discharge when a high voltage is applied in a pulsed manner even when no ultraviolet ray is incident. The time interval of self-discharge when a high voltage is continuously applied to the ultraviolet ray detection tube 26 differs for each ultraviolet ray detection tube used and is generally said to be on the order of several minutes, but varies.

  Further, as the UV detector tube 26 deteriorates, the number of self-discharges increases. Further, the ultraviolet ray detection tube 26 discharges by receiving factors such as sunlight, welding light, plasma, radiation, and cosmic rays in a state where a high voltage is applied in a pulsed manner even when no ultraviolet ray is incident. Since discharge due to factors in the natural world becomes background noise, it is hereinafter referred to as noise discharge.

  As described above, the ultraviolet ray detection tube 26 has self-discharge and noise discharge in addition to the discharge due to the original ultraviolet ray detection due to the ultraviolet ray incident from the flame, and the self-discharge and noise discharge are uncertain discharges, and the ultraviolet rays output by the discharge. The detection pulse signal b includes those due to self-discharge and noise discharge, and even if processed as it is, the flame cannot be accurately determined.

(Configuration of the flame determination unit 14)
The flame determination unit 14 determines flame when the continuous output number N of the ultraviolet detection pulse signal b output from the ultraviolet detection unit 12 matches a predetermined flame determination threshold Nth, and sends the flame determination signal d to the wireless communication unit 20. Output and send to alarm device to alarm.

  In the present embodiment, the flame determination unit 14 is initially set with a first flame determination threshold value Nth1 for determining a flame caused by a writer for arson monitoring, and it is necessary to prevent misreporting due to smoking. Based on the flame sensitivity change instruction by the sensitivity changing unit 16, the detection sensitivity is changed to a low detection sensitivity that becomes the second flame determination threshold Nth2 without determining the flame by the writer.

Here, between the first flame determination value Nth1 having a high detection sensitivity and the second flame determination value Nth2 having a low detection sensitivity, (first flame determination threshold Nth1) <(second flame determination threshold Nth2).
As will be described later, the first flame determination threshold value Nth1 is set to Nth1 = 4, for example, in the first time zone so that the writer's flame due to arson can be determined, and the second time zone is the second time zone. The flame determination threshold Nth2 is set to Nth2 = 8, for example, so that the writer's flame due to smoking is not determined.

  The flame determination unit 14 includes a gate circuit 28, a shift register 30, and a continuous number determination unit 32. The gate circuit 28 operates in response to the synchronization pulse signal a from the oscillation circuit 22, and outputs a bit signal c having a logic level 1 when the ultraviolet detection pulse signal b is input from the ultraviolet detection unit 12, and inputs the ultraviolet detection pulse signal b. If there is no signal, a bit signal c having a logic level 0 is output.

  The shift register 30 includes eight shift stages corresponding to the larger second flame determination threshold Nth2 = 8 for setting a low detection sensitivity, performs a shift operation in accordance with the synchronization pulse signal a, and receives a bit from the gate circuit 28. The signal c is sequentially input and shifted.

  When the continuous number determination unit 32 receives a high sensitivity change instruction signal for setting the first flame determination threshold Nth1 = 4 from the sensitivity change unit 16, the bit signal of 1 to 4 stages of the shift register 30 corresponding to Nth1 = 4 Are input in parallel, and all four stages of bit signals have a logic level 1, that is, the number N of continuous outputs of the UV detection pulse signal b output from the UV detector 12 is equal to the first flame determination threshold Nth1 = If it matches 4, the flame is determined and a flame determination signal d is output to the wireless transmission unit 20.

  Further, when the continuous number determination unit 32 receives a low sensitivity change instruction signal for setting the second flame determination threshold Nth2 = 8 from the sensitivity change unit 16, the bits of the first to eighth stages of the shift register 30 corresponding to Nth2 = 8. When the signals are input in parallel and all the eight bit signals are at the logic level 1, that is, the number N of continuous outputs of the ultraviolet detection pulse signal b output from the ultraviolet detector 12 is the second flame determination threshold Nth2. When the value is equal to 8, the flame is determined and the flame determination signal d is output to the wireless transmission unit 20.

  For this reason, as the continuous number determination unit 32, for example, an AND gate that outputs a logical product by inputting 1 to 4 bit signals of the shift register 30 in parallel and a 1 to 8 bit signal of the shift register 30 are input in parallel. Thus, an AND gate that outputs a logical product can be used.

  The flame determination unit 14 is not limited to the configuration of the gate circuit 28, the shift register 30, and the continuous number determination unit 32, and the number of continuous outputs of the ultraviolet detection pulse signal a output from the ultraviolet detection unit 12 is the first flame determination threshold value. If it can be determined that Nth1 = 4 or the second flame determination threshold value Nth2 = 8, it can be configured appropriately.

  For example, a counter is provided instead of the shift register 30 and a decoder is provided instead of the AND gate of the continuous number determination unit 32. The counter performs a counting operation when the bit signal c from the gate circuit 28 is at a logic level 1, and resets when the bit signal c is at a logic level 0.

  When receiving the first sensitivity change instruction (high sensitivity change instruction) from the sensitivity changing unit 16, the decoder of the continuous number determining unit 32 continuously outputs the bit signal c that becomes bit 1 from the gate circuit 28 and counts the counter. When it is determined that the value is the first flame determination threshold Nth1 = 4, the flame determination signal d is output to the wireless communication unit 20.

  When the decoder of the continuous number determination unit 32 receives a low sensitivity change instruction from the sensitivity change unit 16, the output of the bit signal c having the logic level 1 from the gate circuit 28 continues and the count value of the counter becomes the second flame. When it is determined that the determination threshold Nth2 = 8, the flame determination signal d is output to the wireless transmission unit 20.

(Configuration of sensitivity changing unit 16)
The sensitivity changer 16 divides the day into a first time zone during which no one is present and a second time zone during which a person enters and exits for the purpose of monitoring the fire. An instruction signal is output to make a flame determination state with a high detection sensitivity by the first flame determination threshold Nth = 4, and a low sensitivity change instruction signal is output to the flame determination unit 14 in the second time period from the first flame determination value Nth1 A flame detection state with low detection sensitivity according to the second flame determination threshold Nth2 = 8 is set.

  Therefore, the sensitivity changing unit 16 includes a timer circuit 34 and a threshold changing unit 36. The timer circuit 34 sets, for example, a time zone from 8 o'clock to 8 o'clock the next morning as a first time zone in which the person is unattended, and a time zone from 8 o'clock in the morning to 8 o'clock as a second time zone in which people enter and exit Are set, and the first time zone start signal is output to the threshold value changing unit 36 at 8 o'clock every day, and the second time zone start signal is output to the threshold value changing unit 36 every day at 8 o'clock in the morning.

  When the threshold value changing unit 36 receives the first unmanned first time period start signal from the timer circuit 34, the threshold value changing unit 36 outputs a high sensitivity change instruction signal to the continuous number determining unit 32 of the flame determining unit 14, and the continuous number determining unit 32 is set to the first number. A flame detection state with high detection sensitivity is set by setting the flame determination threshold Nth1 = 4.

  In addition, when the threshold value changing unit 36 receives the second time zone start signal in which a person enters and exits from the timer circuit 34, the threshold value changing unit 36 outputs a low sensitivity change instruction signal to the continuous number determining unit 32 of the flame determining unit 14, and the second flame determining threshold value Nth2 A flame detection state with low detection sensitivity due to = 8.

[Principle of flame judgment and how to determine the flame judgment threshold]
(Principle explanation)
Next, the principle of flame determination according to the present invention will be described by taking as an example the case of determining a small flame by a writer for arson monitoring. This is a case in which the flame determination unit 14 is set to a flame detection state with high detection sensitivity for fire discharge monitoring by setting the first flame determination threshold value Nth1 by a high sensitivity change instruction signal from the sensitivity change unit 16 of FIG. In the following description of the principle, the first flame determination value Nth1 will be described as the flame determination threshold Nth.

  In arson monitoring, for example, it is required to determine a flame when a writer is turned on at a position where the monitoring distance is several meters. Here, the time during which the ultraviolet rays from the flame to be monitored continuously enter the ultraviolet detection tube 26 is defined as the flame duration T1. When firing with a writer, it is assumed that the writer is turned on and off several times to try to ignite it. Therefore, the flame duration T1 of the flame caused by one ignition of the writer is several meters away. For example, when it is set to 5 meters, it is about several hundred milliseconds. Therefore, the flame duration time T1 of the flame determined for monitoring the fire is set to T1 = 500 milliseconds, for example.

  In the present invention, the flame duration T1 is divided into a plurality of times, and an ultraviolet ray detection operation (high voltage application) is performed by the ultraviolet ray detection tube 26 at each divided time, and the ultraviolet ray detection tube 26 is discharged at each division time. If it is continuous, the flame is judged. This flame determination substantially means that the flame is determined by detecting the flame duration T1 of the flame to be monitored.

  Therefore, the number of divisions of the flame duration T1 becomes a flame determination threshold value Nth for determining flame from the number N of continuous outputs of the ultraviolet detection pulse signal, and a value obtained by dividing the flame duration time T1 by the flame determination threshold value Nth (T1 / Nth ) Is the period T2 of the synchronization pulse signal a oscillated by the oscillation unit 10.

(How to determine the flame judgment threshold)
The number of divisions of the flame continuation time T1, that is, the flame determination threshold Nth, is such that noise discharge due to self-discharge of the ultraviolet ray detection tube 26 or the natural world is a single occurrence, so if it is at least divided into two (Nth = 2), The original discharge due to flame can be distinguished from self-discharge and noise discharge. However, if the number of divisions is small, the degree of misjudgment of flames due to self-discharge or noise discharge increases, so the number of divisions is divided into three (Nth = 3), four (Nth = 4), and five (Nth = 5). ), The degree of misjudgment of flame can be lowered.

  On the other hand, when the number of divisions is increased in order to suppress erroneous determination, the cycle of the synchronization pulse signal a generated in the oscillation circuit 22 is shortened, and the number of operations of the circuit unit that is operating by supplying the synchronization pulse signal a is increased. However, power consumption increases and battery life is shortened. Therefore, an optimum division number, that is, a flame determination threshold value Nth is determined in consideration of erroneous determination of flame and an increase in power consumption.

  FIG. 2 is an explanatory diagram showing flame determination when the flame determination threshold Nth is set to Nth = 2, 3, 4, and 5 for a flame with a flame duration time T1 = 500 milliseconds.

  First, the ultraviolet light incident on the ultraviolet ray detection tube 26 from the flame of the writer to be monitored has a flame duration time T1 = 500 milliseconds that exceeds the predetermined discharge start level at times t1 to t2.

  When the flame determination threshold Nth = 2 is set, the period T2 of the synchronization pulse signal a is T2 = 250 milliseconds by dividing the flame duration T1 = 500 milliseconds by the flame determination threshold Nth = 2. When the ultraviolet ray having a flame duration T1 = 500 milliseconds is incident from the time t1, the ultraviolet ray detection tube 26 is continuously discharged twice at an interval of 250 milliseconds, and the continuous output number of the ultraviolet detection field pulse signal a is flame. The flame is determined by detecting that the determination threshold value Nth = 2 is satisfied.

  When the flame determination threshold Nth = 3, the period T2 of the synchronization pulse signal a is T2 = about 167 milliseconds, and the ultraviolet ray detection tube 26 is irradiated with ultraviolet rays having a flame duration T1 = 500 milliseconds from time t1. The battery is discharged three times at intervals of about 167 milliseconds, and the flame is determined by detecting that the number of continuous outputs of the ultraviolet detection field pulse signal a matches the flame determination threshold Nth = 3.

  When the flame determination threshold Nth = 4, the period T2 of the synchronization pulse signal a is T2 = 125 milliseconds. The ultraviolet ray detection tube 26 is continuously discharged four times at intervals of 125 milliseconds when the ultraviolet ray having a flame duration T1 = 500 milliseconds is incident from the time t1, and the number of continuous outputs of the ultraviolet ray detection field pulse signal a is determined as a flame. A flame is determined by detecting that the threshold value Nth = 4.

  Further, when the flame determination threshold Nth = 5, the period T2 of the synchronization pulse signal a is T2 = 100 milliseconds. The ultraviolet ray detection tube 26 is continuously discharged five times at an interval of 100 milliseconds when the ultraviolet ray having a flame duration T1 = 500 milliseconds is incident from time t1, and the number of continuous outputs of the ultraviolet ray detection field pulse signal a is determined as a flame. A flame is determined by detecting that the threshold value Nth = 5.

  Actually, the dischargeable timing of the ultraviolet ray detection tube 26 determined by the flame duration T1 of the time t1 to t2 when the ultraviolet ray exceeding the discharge start level emitted from the flame is incident and the period T2 of the synchronous pulse signal a (high A time lag occurs with respect to the voltage application timing. However, even if there is this time lag, the number of synchronized pulse signals a corresponding to the flame determination threshold value Nth is always included in the flame duration T1, and if the ultraviolet rays are incident during the flame duration T1, the flame determination is performed. The number of continuous discharges determined by the threshold value Nth can be performed.

  Here, when the flame determination threshold value is Nth = 2, that is, when the number of continuous discharges of the flame determination is two times, the flame is erroneously detected due to self-discharge or noise discharge of the ultraviolet ray detection tube 26 that occurs once. There is a problem that the degree of determination becomes high.

  Therefore, if the flame determination threshold Nth is increased and the number of consecutive flame determinations is increased, the degree of erroneous determination of flame decreases. However, for example, when Nth = 5 and the number of continuous discharges of the flame determination is five, the period T2 of the synchronization pulse signal a is as short as T2 = 100 milliseconds, and the circuit unit that operates in response to the synchronization pulse signal operates. There is a problem that the number of operations increases and the power consumption increases accordingly.

  Considering both the erroneous determination of flame and the increase in power consumption, Nth = 3 or 4 is appropriate for the flame determination threshold Nth. Here, for example, Nth = 4 is determined with emphasis on avoidance of erroneous flame determination. Therefore, when the flame of the writer whose flame duration time T1 = 500 milliseconds is to be monitored and the flame determination threshold Nth = 4 is determined, the period T2 of the synchronization pulse signal is T2 = 125 milliseconds.

(Fire monitoring operation)
FIG. 3 is a time chart showing the flame monitoring operation in the embodiment of FIG. 1 when the flame duration T1 = 500 milliseconds, the flame determination threshold Nth = 4, and the synchronization pulse signal period T2 = 125 milliseconds. is there.

  FIG. 3A shows the intensity of ultraviolet light incident on the ultraviolet detection tube 26 from the outside, and is generated with a period T2 in FIG. 3B in a state where ultraviolet light having an intensity exceeding the discharge start level is input. When the high voltage generation circuit 24 is operated by the synchronizing pulse signal a from the oscillation circuit 22 and a high voltage is applied to the ultraviolet detection tube 26, the ultraviolet detection tube 26 is discharged, and the ultraviolet detection pulse signal shown in FIG. b is output.

  Since the ultraviolet ray detection pulse signal b is output at time t1 when no ultraviolet ray exceeding the discharge start level is incident, this is a self-discharge of the ultraviolet ray detection tube 26. In this case, the content of the shift register 30 shown in FIG. 3D is “1000”, the number of consecutive N is N = 1, and since it is less than the flame determination threshold Nth = 4, it is not determined that the flame is continuous. The logical product output by the AND gate of the number determination unit 32 becomes a logical level 0.

  At time t2 to t3, ultraviolet light having an intensity exceeding the discharge start level is incident from the writer flame, and the ultraviolet detection tube 26 is continuously discharged in synchronization with application of a high voltage based on the oscillation pulse signal a. Four consecutive UV detection pulse signals are output. For this reason, the content of the shift register 30 changes to “1000”, “1100”, “1110”, “1111”, and is based on a 4-bit parallel input that becomes a logic level 1 from the shift register 30 by the fourth continuous discharge. The logical product output by the AND gate of the continuous number determination unit 32 becomes a logical level 1, and the flame is determined.

  Times t4 and t5 are cases where the ultraviolet ray detector tube 26 has been subjected to noise discharge due to natural background noise, both of which are single discharge operations, and the contents of the shift register 30 are “1000” and “1001”. The logical product output by the AND gate of the determination unit 32 is bit 0 and is not determined to be a flame.

(Sensitivity change operation)
Next, the sensitivity changing operation by the sensitivity changing unit 16 will be described. FIG. 4A shows the intensity of received light and ultraviolet rays emitted from the flame when the flame determination unit 14 is set to the first flame determination threshold Nth1 = 4 by the high sensitivity change instruction signal from the sensitivity change unit 16. FIG. 4B shows a discharge operation of the detection tube, and FIG. 4B is a determination target when the flame determination unit 14 is set to the second flame determination threshold Nth2 = 8 by the low sensitivity change instruction signal from the sensitivity change unit 16. It shows the intensity of the received UV light emitted from the flame and the discharge operation of the UV detector tube.

  FIG. 5 shows a list of flame duration time T1, synchronization pulse signal period T2, and detection sensitivity to be determined when Nth1 = 4 and Nth2 = 8.

In the high detection sensitivity setting state in which the first flame determination threshold value Nth1 = 4 in FIG. 4A, the cycle T2 of the synchronization pulse signal a is T2 = 125 as shown in Nth = 4 in FIG. Assuming that the ultraviolet ray 100 from the flame of the writer whose flame duration is T = 500 milliseconds is incident on the ultraviolet ray detection tube 26 from time t1 to t2, the high voltage generation based on the synchronizing pulse signal of the oscillation circuit 22 occurs. By applying a pulsed high voltage from the circuit 24, the ultraviolet detection tube 26 is continuously discharged four times at an interval of T2 = 125 milliseconds, and the flame determination unit 14 outputs an ultraviolet detection pulse signal a output from the ultraviolet detection unit 12. Is detected by detecting that the number of continuous outputs coincides with the first flame determination threshold Nth = 4.

In the setting state of the low detection sensitivity with the second flame determination threshold value Nth2 = 8 in FIG. 4B, the period T2 of the synchronization pulse signal a is T2 = 125 milliseconds, and the time t1 is sent to the ultraviolet ray detection tube 26. From the high voltage generation circuit 24 based on the synchronous pulse signal of the oscillation circuit 22, assuming that the flame 200 due to a fire having a long duration compared to the writer flame having a flame duration T1 = 1000 milliseconds from t to t3 is incident. By applying a pulsed high voltage, the ultraviolet ray detection tube 26 is continuously discharged eight times at intervals of T2 = 125 milliseconds, and the flame determination unit 14 continuously outputs the ultraviolet detection field pulse signal a output from the ultraviolet ray detection unit 12. The flame is determined by detecting that the number matches the second flame determination threshold Nth2 = 8.

On the other hand, in the setting state of the low detection sensitivity with the second flame determination threshold Nth2 = 8 in FIG. 4B, the ultraviolet ray 100 is applied to the ultraviolet ray detection tube 26 from the time t1 from the flame of the writer as indicated by the dotted line from the flame duration T. = When incident with over 500 msec, pulse-like high voltage interval of the ultraviolet detector tube 26 is T2 = 125 msec in application of a high electrostatic pressure generation circuit 24 based on the synchronizing pulse signal oscillator 22 outputs In this case, the flame determination unit 14 does not determine a flame because the number of continuous outputs of the ultraviolet detection field pulse signal a does not reach the second flame determination threshold Nth2 = 8, and prevents false alarms. Can do.

[Modification of the present invention]
(Computer circuit)
As another embodiment of the present invention, a computer circuit having a CPU, a memory, and various input / output ports is provided, and the flame determination unit 14 and the sensitivity change unit 16 of FIG. You may do it. In this case, generation of the synchronization pulse signal a by the oscillation circuit 22 can also be performed by a computer circuit.

  FIG. 6 is a flowchart showing flame monitoring processing when a computer circuit is provided. In FIG. 6, in step S1 (hereinafter, “step” is omitted), it is determined whether or not there is a sensitivity change instruction. For example, if a high sensitivity change instruction is determined due to the start of the first unmanned period, the process proceeds to S2, and flame determination is performed. The threshold is set to the first flame determination threshold Nth1 = 4.

  Subsequently, when the generation of the synchronization pulse signal a by the oscillation circuit 22 (which may be a program execution function) is determined in S3, the process proceeds to S4, and the presence or absence of the ultraviolet detection pulse signal b due to the discharge of the ultraviolet detection tube 26 is determined.

  When it is determined that there is an ultraviolet detection pulse signal in S4, the process proceeds to S5, where bit 1 is written in the memory, and the latest continuous 4 bits are read out from the memory corresponding to the first flame determination threshold Nth1 = 4 currently set in S6, If it is determined that all the read 4 bits are bit 1, the process proceeds to S7, where a flame is determined and a flame determination signal is transmitted from the wireless communication unit 20. If it is determined in S4 that there is no ultraviolet detection pulse signal, the process proceeds to S8, bit 0 is written in the memory, and the process proceeds to S7.

  On the other hand, if it is determined in S1 that a low sensitivity change instruction is determined due to the start of the second time zone in which a person enters and exits, the process proceeds to S2, and the flame determination threshold is changed to the setting of the second flame determination threshold Nth2 = 8. Subsequently, when the generation of the synchronization pulse signal a by the oscillation circuit 22 is determined in S3, the process proceeds to S4, and the presence or absence of the ultraviolet detection pulse signal b due to the discharge of the ultraviolet detection tube 26 is determined.

  If it is determined in S4 that there is an ultraviolet detection pulse signal, the process proceeds to S5, where bit 1 is written to the memory, and the latest continuous 8 bits are read from the memory corresponding to the second flame determination threshold value Nth2 = 8 currently set in S6. At this time, if the ultraviolet detection pulse signal b by ultraviolet rays from the writer's flame due to smoking is obtained, all 8 bits read from the memory will not become bit 1 and the flame is not judged and false alarms are prevented.

  On the other hand, if it is determined in S6 that all 8 bits read from the memory are bit 1, the process proceeds to S7, where a flame due to fire is determined and a flame determination signal is transmitted from the wireless communication unit 20.

(Flame detector)
FIG. 7 is a block diagram showing another embodiment of the present invention used as a flame detector. In FIG. 7, the flame monitoring apparatus is provided with a non-polarization unit 40, a constant voltage unit 42, a transmission circuit unit 44, and an operation display unit 46 in order to connect a sensor line from a receiver. The unit 10, the ultraviolet ray detection unit 12, the flame determination unit 14, and the sensitivity change unit 16 are the same as those in the embodiment of FIG.

Nonpolarized 40 terminal for sensing line from receiver L, are non-polar the connection polarity of the C. The flame monitoring device receives a voltage supply of, for example, DC 24V from the receiver, converts it to, for example, DC 5V by the constant voltage unit 42, and supplies it to each unit.

  When the flame determination signal d is input from the flame determination unit 14, the transmission circuit unit 44 transmits a flame determination signal to the receiver, for example, by operating a switching circuit to flow a predetermined flame determination current (reporting current). To do. At this time, a current also flows through the operation display unit 46, and an operation indicator lamp such as an LED is turned on.

  Also in this case, as in the embodiment of FIG. 1, the period T2 of the synchronization pulse signal is fixed to T2 = 125 milliseconds, for example, to determine the flame of the writer due to arson in the first time zone such as night when it is unattended. On the other hand, a first flame determination threshold Nth1 = 4 is set in the flame determination unit 14 by a high sensitivity change instruction signal from the sensitivity change unit 16, while the second time zone such as daytime when a person enters and exits the writer's flame due to smoking In response to a low sensitivity change instruction from the sensitivity changing unit 16, the second flame determination threshold Nth2 = 8 is set in the flame determining unit 14 to monitor the fire.

(Sensitivity change by human sensor)
As another embodiment of the flame monitoring device, a human sensor for detecting a person is provided instead of the timer circuit 34 provided in the sensitivity changing unit 16 of FIG. 1, and a detection signal of the human sensor is output to the threshold changing unit 36. . When the detection signal is not received from the human sensor, the threshold value changing unit 36 outputs a low sensitivity change instruction signal to the flame determining unit 14 to set the second flame determination threshold value Nth2 = 8 and accompanies smoking. A sensitivity change state with low detection sensitivity that prevents false alarms due to the writer's flame.

  On the other hand, when receiving the detection signal from the human sensor, the threshold change unit 36 outputs a high sensitivity change instruction signal to the flame determination unit 14 to set the first flame determination threshold Nth1 = 4, and in the monitoring region. Since there is a possibility of arson due to detection of a person, the writer's flame due to arson is judged and a sensitivity change state with high detection sensitivity capable of alarming is set.

  When the detection signal from the human sensor changes depending on the presence or absence of human detection, the threshold changing unit 36 changes the corresponding flame determination threshold after a predetermined delay time has elapsed from the change in the detection signal. The flame determination unit 14 is instructed. As a result, even if a human sensor frequently repeats the presence / absence of human detection, for example, when multiple people pass through the monitoring area of the flame monitoring device, the detection sensitivity is unnecessarily changed according to the flame determination threshold. Do not repeat.

(Sensitivity change by false alarm avoidance operation)
As another embodiment of the flame monitoring device, a false alarm handling operation unit is provided instead of the timer circuit 34 provided in the sensitivity changing unit 16 of FIG. By operating a switch provided in the operation unit, a false alarm response operation signal is output to the threshold setting unit 36.

  In the normal monitoring state, the threshold setting unit 36 outputs a high sensitivity change instruction signal to the flame determination unit 14 to monitor the fire, and sets the first flame determination threshold Nth1 = 4 to determine the writer flame due to the fire. Sensitive setting sensitivity is set.

In the case where a situation in which false alarms frequently occur due to the flame determination of the flame monitoring device in the sensitivity setting state of the high sensitivity detection sensitivity, the person in charge provided the sensitivity changing unit 16 in order to suppress the frequent occurrence of false alarms. Operate the switch on the operation unit for handling false alarms. The threshold value changing unit 36 that has received the false alarm response operation signal by the switch operation outputs a low sensitivity change instruction signal to the flame determining unit 14 to set the second flame determination threshold value Nth2 = 8, thereby reducing the flame detection sensitivity. State. As a result, the false alarms that have occurred frequently can be stopped or suppressed, and the cause of the false alarms is investigated during that time and necessary countermeasures are taken.

  In the case where the flame determination unit 14 is set to the second flame determination threshold Nth2 = 8 and the detection sensitivity is lowered by the output of the low sensitivity change instruction signal from the threshold change unit 36 accompanying the misinformation handling operation of the misinformation handling operation unit. After a predetermined time has elapsed, a high sensitivity change instruction signal is output from the threshold changing unit 36 to the flame determining unit 14, and a sensitivity setting of high detection sensitivity for determining the flame of the writer due to firing by the original first flame determination threshold Nth1 = 4 It is desirable to automatically recover to the state.

(Other)
The high-sensitivity first flame determination value Nth1 and the low-sensitivity second flame determination value Nth2 set in the flame determination unit may be appropriately determined according to the flame to be determined and the flame to be determined. it can.

  In the above embodiment, the case where the flame detection sensitivity is changed to two levels of high and low is taken as an example. However, the flame detection sensitivity may be changed to three or more stages as necessary.

  For the flame monitoring device that operates on battery power, a low battery failure in which the battery voltage drops below a predetermined voltage may be detected and alarmed.

DESCRIPTION OF SYMBOLS 10: Oscillation part 12: Ultraviolet detection part 14: Flame determination part 16: Sensitivity change part 18: Battery power supply 20: Wireless communication part 22: Oscillation circuit 24: High voltage generation circuit 26: Ultraviolet detection tube 28: Gate circuit 30: Shift Register 32: Continuous number determination unit 34: Timer circuit 36: Threshold change unit 40: Depolarization unit 42: Constant voltage unit 44: Transmission circuit unit 46: Operation display unit

10: Oscillator 12: UV detector 14: Flame determiner 16: Fault determiner 18: Battery power supply 20: Wireless communication unit 22: Oscillator 24: High voltage generator 26: UV detector 28: Gate circuit 30: Shift Register 32: Continuous number determination unit 34: Timer circuit 36: Threshold change unit 38: Count determination unit 40: Depolarization unit 42: Constant voltage unit 44: Transmission circuit unit 46: Operation display unit

Claims (7)

A synchronization pulse signal having a period (T2) as a quotient (T1 / Nth) obtained by dividing a predetermined flame continuation time (T1) in which ultraviolet rays from a flame to be monitored continuously enter by a predetermined flame determination threshold (Nth) An oscillator that outputs a predetermined high voltage in synchronization with the synchronization pulse signal;
An ultraviolet ray detection unit that includes an ultraviolet ray detection tube, and outputs an ultraviolet ray detection pulse signal by a discharge operation of the ultraviolet ray detection tube when ultraviolet rays are incident from the outside in a state where a high voltage is applied from the oscillation unit;
And fire determination unit that determines a flame to output a fire determination signal when the continuous output speed of said ultraviolet detection pulse signal (continuous discharge number) matches with the flame decision threshold,
If a higher detection sensitivity is changed to a smaller value the flame determination threshold, and if the lower detection sensitivity sensitivity changing unit which changes to a larger value the flame determination threshold,
The flame monitoring apparatus characterized by providing.
The flame monitoring device according to claim 1 , wherein the sensitivity changing unit divides a day into a plurality of time zones, and sets different flame determination threshold values for the plurality of time zones to change the detection sensitivity. Features a flame monitoring device.
The flame monitoring device according to claim 2 , wherein the sensitivity changing unit includes:
Dividing a day into a predetermined first time zone in which a person is unattended and a predetermined second time zone in which a person enters and exits, the first time zone is changed to a high detection sensitivity by setting a predetermined first flame determination threshold, the second time zone flame monitoring device and changes to a low detection sensitivity by setting a predetermined second flame determination threshold larger than the first flame determination threshold value.
The flame monitoring device according to claim 1 , wherein the sensitivity changing unit includes a human sensor that detects a person, and sets a predetermined first flame determination threshold when the human sensor detects the person. It is changed to a high detection sensitivity, and when no person is detected by the human sensor, a predetermined second flame determination threshold value that is larger than the first flame determination threshold value is set and changed to a low detection sensitivity. Flame monitoring device.
5. The flame monitoring device according to claim 4, wherein when the human detection state by the human sensor changes, the sensitivity changing unit changes to a corresponding flame determination threshold after a predetermined delay time has elapsed from the change. A flame monitoring device characterized by:
The flame monitoring device according to claim 1 , wherein the sensitivity changing unit sets a predetermined first flame determination threshold value in a normal monitoring state to change the detection sensitivity to a high detection sensitivity, and when a false alarm handling operation is accepted, flame monitoring device and changes to a low detection sensitivity by setting a predetermined second flame determination threshold larger than the first flame determination threshold value.
7. The flame monitoring device according to claim 6, wherein the sensitivity changing unit accepts a false alarm handling operation and sets the second flame determination threshold value to change to a low detection sensitivity, and then the first flame determination after a predetermined time has elapsed. A flame monitoring device characterized in that a threshold value is set to restore high detection sensitivity.

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