JPH05298574A - Fire sense system - Google Patents

Abstract

PURPOSE:To improve sensitivity to a fire and to prevent fire sense ability from lowering by perimitting the threshold value setting means of a reception means to lower a threshold value to a smoke information value (or a heat information value) for a prescribed time when a flame detector detects a flame. CONSTITUTION:The threshold value setting means 5 giving a comparison circuit 6 threshold value voltage Vf connects resistors R1 and R2 in series between a fixed voltage Vcc and the ground and connects the intermediate point thereof to the circuit 6. When a signal is not outputted from a flame detector 1, base current does not flow in a transistor TR1 so that the transistor TR1 is turned off and current flows only in the series circuit of the resistors R1 and R2 in the threshold value setting means 5. When the signal is outputted from the flame detector 1, a timer circuit 4 gives base voltage to the transistor TR1 for a prescribed time, the transistor TR1 turns on, current flowing in the resistor R1 is divided by resistors R2 and R3, the terminal voltage of the timer circuit 4 becomes smaller than terminal voltage during non-counting and a smoke sensor is sensitized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fire detection system for detecting or detecting fire or smoke due to a fire in a monitoring section such as a store, and determining the presence or absence of the fire. A disaster prevention sensor such as a sensor or a heat detector is attached to each place in the monitoring section, and based on the information output from the flame detector and the disaster prevention sensor, the monitoring is performed by a receiving means such as a central monitoring device. The present invention relates to a fire detection system that determines the presence or absence of a fire in a compartment.

[0002]

2. Description of the Related Art FIGS. 5 and 6 are views showing a conventional example of a fire detection system. However, in the conventional example, the flame detector 1
Although the fire detection system including the smoke detector 2 and the smoke detector 2 is mentioned, it is not possible to use a heat detector instead of the smoke detector 2 or to use the smoke detector 2 and the heat detector together. Of course it is possible.

For example, in FIG. 5, reference numeral 2 is a smoke detector for detecting smoke. The smoke sensor 2 outputs an analog value of smoke-related information such as smoke density (hereinafter referred to as "smoke information value"). The smoke sensor 2 can set a unique address. 8 is a smoke detector 2
It is a receiving circuit for receiving a signal from. A multiplex transmission signal line 34, to which the plurality of smoke detectors 2 are sent and wired, is connected to the receiving circuit 8.

The receiving circuit 8 sequentially sends the address signal to each smoke detector 2 through the multiplex transmission signal line 34. At that time, only the smoke detector 2 having the address corresponding to the address signal sends the signal indicating the smoke information value to the receiving circuit 8. The reception circuit 8 sequentially outputs the signals sequentially output from the smoke detectors 2 to the comparison circuit 6 at the next stage by applying analog voltages. A threshold voltage Va is given to the comparison circuit 6 by a constant voltage source 35, and the comparison circuit 6 operates only when the signal output from the reception circuit 8 exceeds the threshold voltage Va. The signal is output to one terminal of the OR circuit 31. The sensitivity of the smoke sensor 2 to smoke can be changed by adjusting the threshold voltage Va.

Reference numeral 1 is a flame detector for detecting a flame. The flame detector 1 detects the weak ultraviolet rays contained in the flame,
A signal is output to the OR circuit 31. The OR circuit 31 includes the comparison circuit 6 or the flame detector 1.
The signal is output when any one of the signal outputs is received.

Reference numeral 7 is a fire alarm circuit for issuing a fire alarm. The fire alarm circuit 7 continuously issues a fire alarm when receiving a signal output from the OR circuit 31.

The receiving circuit 30, the comparison circuit 6, the constant voltage source 35, the OR circuit 31, and the fire alarm circuit 7 constitute a receiving means 30.

However, in the fire detection system having the configuration shown in FIG. 5, the flame detector 1 sometimes detects a lighter or a cigarette fire during smoking, which often causes a false alarm. In order to detect a fire early, if the threshold voltage Va is lowered to make the smoke detector 2 sensitive,
In many cases, warnings were also issued for smoke other than fire, such as cigarette smoke.

Therefore, a fire detection system as shown in FIG. 6 has been proposed. That is, the OR circuit 31 in the fire detection system of FIG. 5 is replaced with the AND circuit 33. In this case, the AND circuit 33 outputs a signal when the signal outputs of the comparison circuit 6 and the flame detector 1 are simultaneously received, and the fire alarm circuit 7 issues a fire alarm.

However, the fire detection system having the configuration shown in FIG. 6 has the following problems. In other words, if there is neither smoke nor flame, it will not give an alarm.
There was a problem that it did not react to the initial fire of only smoke or flames, and that it finally reacted after a large-scale fire. Also, since the fire detection system does not operate unless the signal output of the smoke detector 2 and the signal output of the flame detector 1 are input to the comparison circuit 6 at the same time, the fire detection system is used in a particularly wide monitoring section. When the flame detector 1 and the smoke detector 2 are additionally configured in order to do so, the signals of both are less likely to be simultaneously input to the AND circuit 33 with good timing, and the fire detection cannot be performed stably and accurately. As a result, there is a problem that the fire detection is delayed, that is, the fire detection ability is deteriorated as the system scale is increased.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide a fire detection system capable of changing the sensitivity to fire as needed. To provide.

[0012]

To achieve the above object, the first aspect of the present invention provides a flame detector for detecting a flame and a plurality of smokes for detecting smoke and outputting a smoke information value relating to the smoke. A fire detection system comprising a detector and a receiving means for generating a threshold value for the smoke information value and comparing the smoke information value and the threshold value to perform a fire determination, The receiving means is characterized by including threshold setting means for decreasing the threshold for a predetermined time from when the flame detector detects a flame. The second aspect of the present invention includes a flame detector for detecting a flame, a plurality of heat detectors for detecting heat and outputting a heat information value relating to the heat, and a threshold value for the heat information value. A fire detection system comprising a receiving means for comparing the heat information value and the threshold value to judge a fire, wherein the receiving means detects the flame. It is characterized by comprising threshold setting means for lowering the threshold for a predetermined time from the time.

[0013]

When the flame detector detects a flame, the threshold value setting means of the receiving means lowers the threshold value for the smoke information value (or heat information value) for a predetermined time.

[0014]

The present invention will be described below with reference to the drawings showing its embodiments.

FIG. 1 is a diagram showing an embodiment according to the first present invention. The same parts as those in the conventional example are designated by the same reference numerals.

Reference numeral 5 is a threshold value setting means for applying a threshold voltage Vf to the comparison circuit 6, which is constructed as follows. That is, the resistor R1 and the resistor R2 are connected in series between the fixed voltage Vcc and the ground voltage, and the resistor R1
The midpoint between 1 and the resistor R2 is connected to the threshold voltage input of the comparator circuit 6. The resistor R3 and the transistor TR1 are connected in series between the intermediate point and the ground voltage. At this time, the emitter of the transistor TR1 is grounded, and the resistor R3 is connected to the transistor TR1.
Connected to the collector. Also, the transistor TR
A timer circuit 4 is connected to the base of 1. The flame detector 1 is connected to the timer circuit 4 so as to receive a signal output from the flame detector 1 to clock a predetermined time and always output a signal during the timing operation. In this embodiment, one flame detector 1 is used, but a plurality of flame detectors 1 may be connected by signal lines according to the size of the monitoring section to be installed.

In the threshold value setting means 5 having the above construction, when there is no signal output from the flame detector 1, the base current does not flow in the transistor TR1.
R1 is off, and current flows only in the series circuit of the resistors R1 and R2. The terminal voltage Vf1 of the resistor R2 at this time is given to the comparison circuit 6 as a threshold voltage Vf.

When a signal is output from the flame detector 1, the timer circuit 4 applies a base voltage to the transistor TR1 for a predetermined time, at which time the transistor TR1 is turned on and a current flowing through the resistor R1. Is shunted by the resistors R2 and R3, and the terminal voltage Vf2 of the resistor R2 at this time is used as the threshold voltage Vf.
Given to. Therefore, the terminal voltage Vf2 of the timer circuit 4 during the time measurement is smaller than the terminal voltage Vf1 of the timer circuit 4 during the non-time measurement (Vf2 <Vf2 <
Since Vf1), the desired variable control of the threshold voltage Vf can be performed depending on the presence / absence of signal output from the timer circuit 4. The difference between the terminal voltage Vf1 and the terminal voltage Vf2 is determined by the resistance values of the resistors R1, R2, and R3.

On the other hand, at the signal side input of the comparison circuit 6,
Similar to the conventional example, the output of the receiving circuit 3 to which the multiplex transmission signal line 34 to which the plurality of smoke detectors 2 are sent and connected is connected is connected. Since the smoke sensor 2 generally has a narrower sensing range than the flame detector 1, a larger number than the flame detector 1 is required, but it depends on the size of the monitoring section to be installed. Need a number. The output of the comparison circuit 6 is connected to the fire alarm circuit 7.

The smoke sensor 2 outputs an analog value of smoke-related information such as smoke density, that is, a smoke information value, as in the conventional example. Each smoke sensor 2 can set a unique address. The receiving circuit 8 sequentially sends the address signal to each smoke detector 2 through the multiplex transmission signal line 34. At that time, only the smoke detector 2 having the address corresponding to the address signal sends the signal indicating the smoke information value to the receiving circuit 8. The receiving circuit 8 sequentially converts the signals sequentially output from the smoke detectors 2 into analog voltages of corresponding levels, and sequentially outputs the analog voltages to the comparison circuit 6 at the next stage. The comparison circuit 6 outputs a signal only when the signal output from the reception circuit 8 exceeds the threshold voltage Vf.

The reception circuit 8, the comparison circuit 6, the threshold value setting means 5, and the fire alarm circuit 7 constitute a reception means 3 such as a central monitoring device.

FIG. 2 is a time waveform diagram showing an operating state of the fire detection system in the first embodiment of the present invention having the above-mentioned configuration.

First, the threshold voltage Vf in the state where the flame is not detected is given to the comparison circuit 6 by the terminal voltage Vf1 as shown in FIG. 2 (c).
Here, when the flame detector 1 detects a flame as shown in FIG. 2A, the timer circuit 4 starts timing as shown in FIG. 2B. At the same time, as shown in FIG. 2C, the threshold voltage Vf changes to the terminal voltage Vf2.
And the smoke detectors 2 become more sensitive. The threshold voltage Vf maintains the low level voltage Vf2 during the time counting operation of the timer circuit 4, but when the timer circuit 4 is timed, that is, when a predetermined time T has elapsed from the start of measurement, The threshold voltage Vf is a high level voltage Vf
Return to 1.

FIG. 3 is a view showing an embodiment according to the second invention, but the difference from the embodiment according to the first invention is that the smoke sensor 2 is a heat sensor 11. Only points. Therefore, in the fire detection system of the second embodiment of the present invention, the operating state of the fire detection system of the first embodiment of the present invention is the same as that of FIG. 2 described above.

FIG. 4 shows an embodiment according to both the first invention and the second invention (hereinafter referred to as "third embodiment"). The fire detection system of the third embodiment is the fire detection system of the first embodiment of the present invention using the smoke detector 2 and the fire detection system of the second embodiment of the present invention using the heat detector 11. It has a structure that is combined with the system. The fire detection system uses a timer circuit 4 connected to the flame detector 1 to provide a threshold voltage V for the smoke detector 2.
f and the threshold voltage Vg for the heat sensor 11 are controlled simultaneously. In addition, the output of the comparison circuit 6 for the smoke sensor 2 and the comparison circuit 15 for the heat sensor 11
The output of is connected to one fire alarm circuit 13, and when the signal outputs from the comparison circuits 6 and 15 are simultaneously input, the fire alarm is continuously emitted, but of course, The fire alarm may be continuously issued when either of the signal outputs of both is input.

With the structure according to the third embodiment, fire detection can be made more accurate.

[0027]

As described above, in the fire detection system of the present invention, the smoke information value output from the smoke detector and the heat information value output from the heat sensor for a predetermined time after the flame is detected, respectively. Since the threshold value for is set to a lower value, it does not generate a false alarm by distinguishing cigarette smoke or lighter fire during smoking as a fire, and it also responds to an initial fire of only smoke or flame. Therefore, the fire can be detected accurately and early. Even if flame detectors and smoke detectors (heat detectors) are added in order to use the fire detection system in a particularly wide monitoring area, all flame detectors and smoke detectors (heat detectors) are always available. Since the flame detection and smoke (heat) detection are possible, even if the scale of the system is increased, the fire detection ability is not deteriorated, and the fire detection system that can detect a fire accurately and early can be configured.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment according to the first invention.

FIG. 2 is a time waveform chart showing an operating state of the embodiment of the present invention.

FIG. 3 is a diagram showing an embodiment according to the second invention.

FIG. 4 is a diagram showing an embodiment according to the first invention and the second invention.

FIG. 5 is a diagram showing a first conventional example.

FIG. 6 is a diagram showing a second conventional example.

[Explanation of symbols]

 1 Flame detector 2 Smoke detector 3 Receiving means 5 Threshold setting means

Claims (2)

[Claims] 1. A flame detector for detecting a flame, a plurality of smoke detectors for detecting smoke and outputting a smoke information value relating to the smoke, and a smoke information generating threshold for the smoke information value. A fire detection system configured to include a reception unit that compares a value with the threshold value to determine a fire, wherein the reception unit has a predetermined time from when the flame detector detects a flame. A fire detection system comprising threshold setting means for lowering the threshold during the period. 2. A flame detector for detecting a flame, a plurality of heat detectors for sensing heat and outputting a heat information value relating to the heat, and a heat information generating threshold for the heat information value. A fire detection system configured to include a reception unit that compares a value with the threshold value to determine a fire, wherein the reception unit has a predetermined time from when the flame detector detects a flame. A fire detection system comprising threshold setting means for lowering the threshold during the period.