JPS6356597B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a smoke detection method that is effective for use in smoke detection type fire detectors such as ionization smoke detectors and optical smoke detectors.

Conventionally, ionization smoke detectors detect smoke from changes in ionization current by installing a pair of voltage-applied electrodes in a detection chamber into which smoke flows, and ionizing the inside of the electrodes with radiation. Many optical smoke detectors have been manufactured that detect smoke by guiding a light flux emitted from a light source into a similar detection chamber and detecting scattered light or attenuated light due to the smoke using a light receiver.

Malfunctions of these smoke detectors are often caused by insects entering the detection chamber.

Therefore, the present inventor previously proposed in Japanese Patent Application No. 56-129350 that the detection chamber into which smoke flows has its own inflow characteristics, and that it is possible to distinguish signals based on insect intrusion from these inflow characteristics. We focused on this and proposed a smoke detection method that eliminates the above malfunction.

In other words, whether it is an ionization smoke detector or an optical smoke detector, the smoke detector is connected to a wall that allows smoke to flow in order to remove noise signals, prevent turbulence from entering, and prevent outside light from entering. surrounded by
Generally, it forms a detection chamber. However, the formation of this detection chamber acts as a kind of resistance to the inflow of smoke, so for example, by placing the detection chamber in an atmosphere filled with smoke at a certain concentration and measuring the change in the detection signal. When plotted as a graph with time on the horizontal axis and detected signal amount (voltage: V) on the vertical axis, a curve A as shown in FIG. 1 is obtained. On the other hand, when an insect invades the detection chamber and a disturbance occurs, a steep change as shown in curve B appears. The above curve A when smoke flows in is the size of the detection chamber,
Although it is unique and determined by the structure etc., when an insect invades, it appears as a steep change regardless of which detection chamber it is in, so it is possible to prevent false alarms due to insect intrusion from this difference in characteristics. By paying attention to this, we obtained a configuration as shown in Fig. 2.

FIG. 2 is a block diagram showing a schematic configuration of a smoke detection method according to the invention related to the earlier application, in which a detection section 1 that detects smoke such as an ionization type or an optical type and generates a detection signal, and the detection section 1 that detects smoke and generates a detection signal a reference signal generating section 2 having a change over time determined from the inflow characteristics of section 1;
a starting section 3 that generates a drive signal for starting the operation of the reference signal generating section 2 in response to the initial detection signal of the detecting section 1; A signal comparator 4 that compares with a reference signal and generates an output when the detected signal exhibits a change below the reference signal; an integrator 5 that integrates the output of the signal comparator 4 for a specified time; The detection signal generating section 6 generates a smoke detection signal only when the integral amount reaches a specified value.

Next, the operation of the smoke detection method according to the invention related to the earlier application configured as described above will be explained in detail based on FIG. 3 showing voltage changes depending on various situations.

FIG. 3 is a graph with voltage on the vertical axis and time on the horizontal axis. In normal times when there is no smoke or insect invasion, the detection signal of the detection unit 1 and the reference signal of the reference signal generation unit 2 are Either the signals are not together, or the detected signal slightly exceeds the reference signal, so that no output is produced from the signal comparator 4.

However, for example, an insect invasion occurs at time t ₀ , and the detection signal of the detection unit 1 changes accordingly.
If there is a sudden change like B ₁ , the detection part 1
its operating voltage in response to the initial detection signal of
The starting unit 3 with V ₀ operates at time t ₁ and starts the reference signal generating unit 2 . Then, the reference signal generating section 2 generates a reference signal that draws a curve that increases with time determined from the inflow characteristics of the detecting section 1 as shown by the curve _A0 . This reference signal
Since A ₀ rises almost in accordance with the inflow characteristics, there is no steep rise unlike the detection signal B ₁ , and therefore the detection signal B ₁ does not exhibit a change below the reference signal A ₀ , so signal comparison is possible. No output is produced from section 4.

Note that when the invading insect escapes halfway, the detection signal B ₁ is output as shown from time t ₂ to t ₃ in FIG.
There are times when the signal A temporarily changes to become lower than the reference signal _A0 , but at this time, the output generated from the signal comparator 4 is once input to the integrator 5 and integrated, so the specified integral value of the integrator 5 If is set appropriately, such a temporary output will not reach the specified integral value, and therefore the sensing signal generating section 6 will not generate a smoke sensing signal. Furthermore, it has been empirically confirmed that the detection signal generated by insect invasion is much larger than the detection signal generated by smoke to be detected.
By appropriately setting the maximum value of the reference signal A ₀ so that it never exceeds the detection signal at the time of insect invasion, it is possible to prevent the output from the signal comparison unit 4 from being generated regardless of the insect intrusion residence time. can.

Next, instead of insect invasion as described above, smoke is generated at time t ₀ ′, and accordingly, the detection unit 1
When the detection signal gradually changes as shown by curve B ₂ , the starting section 3 operates at time t ₁ when this detection signal exceeds the operating voltage V ₀ and starts the reference signal generating section 2 . Then, similarly to the above, the reference signal generator 2 generates a reference signal as shown by the curve _A0 . This reference signal A ₀ is determined by the inflow characteristics and rises, so if the detection signal is caused by smoke, it will never change more than this reference signal A ₀ , so it is always There are times when the detection signal _B2 is lower than the reference signal _A0 . Assuming that the time at which the signal falls below is _t4 , an output is generated from the signal comparator ₄ at this time t4, and integration by the integrator 5 is started. Then, at time _t5 , when the predetermined integral value, which is appropriately set as described above, is reached, an output is generated from the integrator 5, and a smoke sensing signal is generated from the sensing signal generating section 6.

However, as mentioned above, according to the invention related to the earlier application _, it is possible to effectively eliminate malfunctions caused by sudden changes such as those caused by the invasion of insects; It also had the disadvantage that it would work. That is, it has the disadvantage that it operates even for smoke that is not as concentrated as fire smoke, such as cigarette smoke as shown by curve _B3 in FIG. 5, for example.

Therefore, as a means to eliminate this drawback, the operating voltage V ₀ of the starter 3 is changed to a voltage V ₁ as shown by the broken line.
By setting it to a high value, it is possible to prevent it from operating in low concentration smoke. but,
If such a method is used, this new operating voltage V ₁ will also act on real smoke from a fire, as shown by curve B ₂ , so the operation of the entire sensor will be controlled by curve B ₂ . It starts at time _t6 , which exceeds _V1 , and is later than time _t4 , when the signal comparator 4 generates an output when the operating voltage is set to _V0 . This is not desirable considering the original mission of the fire detector. In other words, the mission of a fire detector is to detect fire quickly and accurately.

The smoke detection method according to the present invention is capable of accurately detecting fire without causing the above-mentioned drawbacks, and will be described in detail below with reference to the drawings.

FIG. 4 is a block diagram showing a schematic configuration of the smoke detection method according to the present invention, and shows the detection section 1, starting section 3, integrator 5, and sensing signal in the smoke detection method according to the previous invention shown in FIG. The generation unit 6, the upper limit reference signal generation unit 20 corresponding to the reference signal generation unit 2, and the upper limit signal comparison unit 40 corresponding to the signal comparison unit 4,
A lower limit reference signal generating section 7 having a change over time determined from the inflow characteristics of low concentration smoke such as cigarette smoke, a lower limit signal comparing section 8 that generates an output when the curve signal exhibits a change exceeding the lower limit reference signal, and an upper limit signal generating section 7. It is constructed by adding an AND circuit 9 which calculates the logical product of the signal comparison section 40 and the lower limit signal comparison section 8 and outputs the result to the integrator 5.

Next, the operation of the smoke detection system according to the present invention configured as described above will be explained in detail based on FIG. 5, which shows voltage changes depending on various situations.

Similar to FIG. 3, FIG. 5 is a graph in which voltage is plotted on the vertical axis and time is plotted on the horizontal axis, and curves that are the same as those in FIG. 3 are given the same symbols. That is, in normal times when there is no smoke generation or insect invasion, the detection signal of the detection section 1 and the reference signals of both reference signal generation sections 20 and 7 are either not present, or the detection signal is slightly higher than both reference signals. , and therefore no output is generated from at least the upper limit signal comparator 40, so no output is generated from the AND circuit 9.

Further, for example, when an insect invades and the detection signal of the detection unit 1 suddenly changes as shown by curve _B1 , the starting unit 3 operates at time _t1 ,
Both reference signal generators 20 and 7 are started. Then, the upper limit reference signal generating section 20 generates a reference signal that draws a curve that increases with time determined from the inflow characteristics of the detecting section 1 as shown by the curve _A0 , and the lower limit reference signal generating section 7 As shown in curve A ₁ , the rate increases with time as determined by the inflow characteristics of low-concentration non-fire smoke such as cigarette smoke, and eventually the difference between fire-related and other low-concentration smoke increases. A curved reference signal is generated that serves as a distinguishing threshold signal. Since the curve B ₁ does not exhibit a change below the curve A ₀ , no output is generated from the upper limit signal comparison section 40 , but since the curve B 1 exhibits a change exceeding the curve A ₁ , no output is generated from the lower limit signal comparison section 8 . Output occurs. However, since the output is cut off by the AND circuit 9, smoke detection drive does not occur in the end.

Next, if smoke from a fire occurs at time t ₀ ' and changes as shown by curve B ₂ , then
The starting section 3 operates at time _t1 and starts both the reference signal generating sections 20 and 7. Then, as described above, both reference signal generating sections 20 and 7 generate both reference signals shown by curves A ₀ and A ₁ . detection signal curve
B ₂ falls below the upper limit reference signal curve A ₀ from time t ₄ ,
Furthermore, since it exceeds the lower limit reference signal curve _A1 , both signal comparison sections 40 and 8 produce outputs.
This output passes through the AND circuit 9 and is input to the integrator 5, where integration is started. When the specified integral value T ₀ , which is set appropriately, is reached at time t ₅ ,
An output is generated from the integrator 5, and a smoke sensing signal is generated from the sensing signal generating section 6.

The characteristic parts of the smoke detection method of this invention are as follows.

In other words, low concentration smoke such as cigarette smoke
If the signal occurs at _t0 '' and changes as shown by curve _B3 , the starting section 3 operates at time _t1 and starts both reference signal generating sections 20 and 7,
Both reference signals designated drive A ₀ and A ₁ are generated.
Then, the detection signal curve B ₃ becomes lower than the upper limit reference signal curve A ₀ from time t ₇ and is lower than the lower limit reference signal curve
Since the value exceeds A ₁ , both signal comparison units 40 and 8
An output is generated from the integrator 5 via an AND circuit 9.
is input to start the integration. However, since the lower limit reference signal curve A ₁ is preset to change more than the detection signal curve B 3 due to such low concentration smoke, the detection signal curve _{B 3 changes} to the lower limit reference signal at time t ₈ . It is also below curve _A1 . Then,
Since the output from the lower limit signal comparison section 8 is stopped, the output from the upper limit signal comparison section 40 is cut off by the AND circuit 9. Therefore, the specified value T ₀ of the integrator 5
By setting , which is sufficiently longer than the time T ₁ from time t ₇ to time t ₈ , a smoke detection signal will not be generated in the end.

An embodiment of the specific circuit configuration of the smoke detection method of the present invention is shown in FIG. 6. FIG. 6 shows an embodiment in which an ionization type smoke detection section is used as the detection section 1. Reference chambers Ch ₁ and Ch ₂ , which have been ionized by a radiation source RI, are connected in series, and the gate electrode of a field effect transistor FET for detecting potential changes is connected to the series connection point to form a detection section 1. There is. The upper limit reference signal generating section 20 includes a parallel circuit consisting of a capacitor C ₀ and a resistor R ₀ , and two circuits connected in series that regulate the current flowing into the parallel circuit and divide the signal voltage.
It is formed from two resistors R ₁ and R ₂ . The lower limit reference signal generator 7 includes two resistors connected in series that divide the output signal of the upper limit reference signal generator 20.
It is formed from R ₅ and R ₆ . The starting section 3 is controlled by a resistor R ₃ and a first transistor Q ₁ that detect a current generated by an increase in the detection voltage of the detecting section ₁ , and the upper limit reference signal generating section 20. and a second transistor _Q2 that controls the flow of current into the transistor Q2. The upper limit signal comparison section 40 is formed of a comparator CP ₁ whose input side is connected to the upper limit reference signal generation section 20 and the detection section 1 . Lower limit signal comparison section 8
is formed of a comparator CP ₂ whose input side is connected to the lower limit reference signal generator 7 and the detector 1. The integrator 5 has a capacitor C1 that accumulates the output of the AND circuit 9, which calculates the logical product of the comparator _CP1 and the comparator _CP2 , via a resistor _R4 , and when the charge amount of the capacitor _C1 reaches a specified value _. It is formed from a Zener diode _Z1 that detects. The sensing signal generating section 6 is formed of an SCR triggered by the output of the integrator 5.

In the embodiment of the smoke detection method of the present invention configured as described above, a low voltage signal is output to the output side of the field effect transistor FET of the detection unit 1 during normal times when no smoke is generated or insects are invaded. However, since this voltage level does not exceed the Zener voltage of the Zener diode Z ₂ that defines the operating voltage of the starter 3, no potential difference occurs between the ends of the resistor R ₃ of the starter 3, and therefore the starter 3 does not operate, both reference signal generators 20 and 7 are not driven. However, since the normal level signal of the detection unit ₁ is applied to the detection signal input side of the comparator CP 2 and exceeds the lower limit reference signal input side, an output is generated in the comparator CP ₂ . Its output is cut off by AND circuit 9.

However, if some kind of smoke is generated or an insect enters, a high voltage detection signal is generated at the output side of the detection part 1, exceeding the Zener voltage of the Zener diode _Z2 , and a current flows, thus causing the starting part to 3
A potential difference is generated between both ends of the resistor _R3 , and the first transistor _Q1 is turned on. Then, the second transistor Q ₂ connected to this is also _turned on, so that the capacitor C ₀ of the upper limit reference signal generating section ₂₀ is Charging is performed at , and the potential rise at the series connection point of resistors R ₁ and R ₂ due to the rise in the potential of capacitor C ₀ becomes the upper limit reference signal. Further, the lower limit reference signal generating section 7 divides the upper limit reference signal using resistors R ₅ and R ₆ and uses the potential rise at the voltage dividing point as the lower limit reference signal. The rising reference signals and the detection signal are connected to the comparators CP 1 and CP ₁ , respectively.
Compare by CP ₂ . At this time, in the case of smoke generation due to fire, the detection signal changes below the upper limit reference signal and exceeds the lower limit reference signal, so outputs are generated from both comparators CP ₁ and CP ₂ .
An output is sent from the AND circuit 9, and the capacitor _C1 is charged via the resistor _R4 . When the charging voltage exceeds the Zener voltage of the Zener diode _Z1 , a current flows to the gate of the SOR, and the SOR turns on. and a smoke detection signal is sent out.

Furthermore, in the case of low concentration smoke such as cigarette smoke, the detection signal exhibits a change lower than both reference signals, so the comparator CP ₁ of the upper limit signal comparison section 40
An output is generated in , but no output is generated in the comparator CP ₂ of the lower limit signal comparison section 8.
The AND circuit 9 maintains the cut-off state and no smoke detection signal is generated.

Further, when the detection signal is due to insect invasion, the detection signal exhibits a change exceeding both reference signals, so an output is generated from the comparator CP ₂ of the lower limit signal comparison section 8, but the comparator CP ₁ of the upper limit signal comparison section 40 is output. Because it does not produce any output from
AND circuit 9 maintains the cut-off state, so SCR
It is never turned on.

As described above, the smoke detection method according to the present invention is
With an extremely simple configuration, it is possible to detect a detection signal due to the inflow of smoke associated with a true fire, a relatively gentle false detection signal such as that caused by smoke other than a fire, or a steep false detection signal such as that caused by insect intrusion. Since each detection chamber can be accurately and quickly identified according to its unique inflow characteristics, it is possible to provide a low-cost and high-performance smoke detector.

[Brief explanation of drawings]

FIG. 1 is a characteristic curve diagram for explaining the smoke inflow characteristics of the smoke detection chamber, FIG. 2 is a block diagram showing the schematic configuration of the smoke detection method according to the invention related to the earlier application, and FIG. 4 is a graph diagram showing the relationship between time, detection signal, and reference signal for use in explaining the operation of the smoke detection method according to the invention related to the application; FIG. 4 is a block diagram showing a schematic configuration of the smoke detection method according to the invention; FIG. 5 is a graph showing the relationship between time, detection signal, and both reference signals for use in explaining the operation of the smoke detection method according to the present invention, and FIG. 6 is a circuit configuration using the smoke detection method according to the present invention. FIG. 2 is a circuit diagram showing one embodiment of the present invention. 1... Detection section, 20... First reference signal generation section, 7... Second reference signal generation section, 40, 8, 9
...Signal comparison generator.

Claims (1)

[Claims] 1 a detection unit that detects smoke and generates a detection signal;
a first reference signal generating section that is started by the initial detection signal of the detection section and generates an upper limit reference signal while changing over time in accordance with the smoke inflow characteristics of the detection section; and a first reference signal generation section that is started by the initial detection signal of the detection section. and a second reference signal that generates a lower limit reference signal lower than the upper limit reference signal while changing over time in accordance with the smoke inflow characteristics of the detection section.
compares the upper and lower limit reference signals with the detection signal, and outputs a smoke detection signal when the detection signal exceeds the lower limit reference signal and falls below the upper limit reference signal. 1. A smoke detection method, comprising: a signal comparison and generation section that generates a signal, and detects smoke based on the presence or absence of a smoke detection signal from the signal comparison and generation section.