JPH0219899Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement in an accumulation type fire detector that sends an alarm signal to a receiver when the output of the fire detection section continues for a set accumulation time.

Conventionally, in this type of storage type fire detector, the fire detection output for detecting heat or smoke caused by a fire is 20~
The alarm signal is sent to the receiver when it continues for a set accumulation time within a range of 60 seconds, so even if an instantaneous fire detection output is obtained due to a cause other than a fire, , to avoid false alarms.

Incidentally, the above-mentioned storage type fire detector has the advantage of rarely emitting false alarms, but on the other hand, in order to detect fires early, it is desirable that the storage time is short; When a fire alarm is issued by the receiver due to the alarm signal from the detector, in order to check whether it is a false alarm, operate the recovery switch on the receiver to cut off the power supply to the detector, and then try again. If the fire alarm is issued again after power is supplied, it is generally assumed that there is a fire, and confirmation of whether this is a false alarm is done in the same way for storage type sensors. Therefore, it is desirable to minimize the storage time.

However, with conventional storage type fire detectors,
Considering the factors that cause false alarms, we set a predetermined accumulation time that will not cause false alarms.As a result, when we actually installed fire detectors, we found that there was a greater risk of false alarms than we initially expected. Even if it is found that the storage time is low, shortening the set storage time at the site requires replacing the circuit elements on the printed circuit board.
In practice, it is not possible to change the accumulation time, and even though there is no risk of false alarms, fire detection is now performed based on a preset accumulation time, which poses the problem of hindering early detection of fires. Ta.

In addition, for maintenance and inspection of fire detectors, use a tester that has a bowl-shaped heat or smoke generating part that covers the detector at the tip of the operating rod to confirm that the detector reliably detects heat or smoke. During this work, it is necessary to hold the operating rod of the tester and point the generator toward the sensor, and the sensor must be mounted on the ceiling and the sensor must be located within one building. Considering that there are many installed in

In particular, in the case of a storage type sensor, it takes time to send out an alarm signal after detecting heat or smoke, and in addition to the above-mentioned problem, there is also the drawback of poor workability.

The present invention has been made in view of the above, and is configured so that the set accumulation time can be changed simply and easily by providing a switch means for shortening the set accumulation time in an accumulation type fire detector. be.

Hereinafter, the present invention will be explained based on the drawings.

FIG. 1 is a circuit diagram showing one embodiment of the present invention, taking a photoelectric smoke detector as an example.

First, to explain the configuration, power is supplied from terminals 1 and 1' connected to the power signal line drawn out from the receiver, and a noise cutting filter consisting of inductances L ₁ and L ₂ and capacitors C ₁ and C ₂ is used. A diode bridge DB installed next to the diode bridge DB makes it possible to apply a DC power with the specified polarity even if the power supply polarities of terminals 1 and 1' are switched. A current circuit 2 supplies constant voltage and constant current.

The detection light is irradiated to the smoke detection section using pulsed light from a light emitting diode LED that is driven to emit light by transistors Q1 and Q2, which are turned on and off using a pulse signal from terminal i of IC3. The light scattered by the smoke is a photodiode.
The light is received by the PD, amplified and outputted by amplifier 4, and then
It is input to terminal b of No. 3. As will be explained later, the IC 3 is equipped with a comparator that determines whether the light receiving output of the amplifier 4 exceeds a predetermined value, and a counter that opens a gate based on the output of the comparator and counts pulses. When the counter reaches the set count determined based on the set accumulation time, an output is generated at terminal g, turns on the thyristor SCR, and increases the alarm current by making the impedance between terminals 1 and 1' low. , to send out an alarm signal.

In this way, it has a counter as an accumulation means.
The series connection point of resistor R16 and switch 5 is connected to the e terminal of IC3, and when switch 5 is open as shown in the figure, an H level signal is applied to the e terminal of IC3, and the counter is started based on the set accumulation time. The set count of the counter is set to m, and when switch 5 is closed, an L level signal is applied to the e terminal, and at this time, the set count of the counter is
The setting is changed from m to n (where m>n) to shorten the storage time.

FIG. 2 shows a circuit block of IC3 in the embodiment of FIG. 1, in which a clock pulse from a master clock 6 which oscillates a clock pulse with a time constant determined by a resistor R9 and a capacitor C5 is divided by a counter 7. , outputs a driving pulse once every 4 or 5 seconds. Each of these drive pulses is input to one of AND gates A1 and A2, and the other of AND gate A2 is input to switch 5.
An H or L level signal determined by on/off is added. On the other hand, a signal from the switch 5 inverted by the inverter I1 is applied to the AND gate A1. Therefore, when switch 5 is open, AND gate A2 is allowed and a clock pulse with a period of 5 seconds is applied to one shot multi 8 through OR gate OR1, and when switch 5 is closed, AND gate A1 is allowed. A clock with a period of 4 seconds is applied to the one-shot multi 8, and the one-shot multi 8 is connected to the resistor R11 and the capacitor C7.
A light emission driving pulse having a predetermined pulse width based on a time constant is applied to the driving section of the light emitting diode LED from the terminal i via the amplifier 9.

On the other hand, H determined by the on/off of switch 5
Or, the L level output is input to the AND gate A4, and the inverted output of the inverter I1 is input to the AND gate A3.
By turning off, one of the AND gates A3 and A4 is selected to be in the permissible state.

A predetermined output terminal of a counter 10 provided as an accumulation means is connected to the other input of the AND gates A3 and A4, and in this embodiment, the terminal that outputs the set count m=6 is connected to the AND gate A4. , On the other hand, the terminals that output at the set count n = 2 are connected to AND gate A3, and these counter outputs are connected to AND gate A in the allowable state.
3 and A4, is converted into a pulse signal having a predetermined pulse width by the one-shot multiplier 11 via the OR gate OR2, and is applied to the gate of the thyristor SCR from the terminal g via the amplifier 12.

The clock pulses counted by the counter 10 are:
A clock synchronized with the Q output of the one shot multi 8 is generated by a time constant circuit connected to terminals m and n and an inverter I2.
The output (H level) of the flip-flop 13 resets the counter 10 via the OR gate OR3, but when a fire is detected, when the light reception signal input to terminal b goes around the reference value set by the variable resistor VR once. Then, the comparator 14 applies an H level output to the flip-flop 13 to make it =L, thereby releasing the reset of the counter 10 and causing the counter 10 to count clock pulses.

Next, to explain the operation of shortening the accumulation operation time by operating the switch 5, when the switch 5 is turned off, the set count of the counter 10 is
Since m=6 and in this embodiment, the period of the clock pulse of the counter 10 is 5 seconds, the set accumulation time is 30 seconds.

That is, when the switch 5 is turned off, an H level signal is applied to the AND gate A2 and becomes a permissible state.On the other hand, the AND gate A1 becomes a disabled state due to the L level output of the inverter I1, and the period divided by the counter 7 A clock pulse of 5 seconds triggers the one-shot multi 8 through the OR gate OR1, so that the light emitting diode LED is driven to emit light by the pulse with a period of 5 seconds, and the counter 10
A clock pulse with a period of 5 seconds is also applied to the CK terminal of .

On the other hand, AND gate A3 is connected to the L of inverter I1.
Although it is in the prohibited state due to the level output, AND gate A4 is in the allowed state after receiving the H level input.
Therefore, the output end of the counter 10 with count m=6 is selected.

In this state, if smoke flows into the smoke detector and the level of the light reception signal applied to terminal b exceeds the reference value provided by the variable resistor VR, the reset of the counter 10 is canceled by the H level output of the comparator 14. The counter 10 starts counting the clock pulses, reaches 6 counts after 30 seconds, and the terminal m becomes H level, and the AND gate A4
and the one-shot multi 11 via the OR gate OR2, and therefore, a signal pulse with a predetermined pulse width is sent from the Q terminal via the amplifier 12 to the terminal G.
The signal is applied to the gate of thyristor SCR, turning on thyristor SCR and sending out a warning signal to the receiver.

Next, if switch 5 is turned on, terminal e
becomes L level, and therefore, AND gate A
2, A4 becomes inhibited and AND gate A1,
A3 becomes the permissible state.

Therefore, based on the clock pulse with a period of 4 seconds divided by the counter 7, the light emitting diode LED
is driven to emit light, and a clock pulse is applied to the counter 10, and the output terminal of the counter 10 at count n=2 is selected due to the permission state of the AND gate A3.

Therefore, if fire detection is performed in this state,
When the counter 10 counts two clock pulses with a period of 4 seconds, it generates an H level output at the terminal n and outputs an alarm pulse to the gate of the thyristor SCR, and the set accumulation time at this time is 8 seconds. It will be shortened to .

Figure 3 is a cross-sectional view of the structure of a photoelectric smoke detector equipped with the circuit configuration shown in Figures 1 and 2.
An example of the structure of the switch 5 is shown.

That is, the sensor body 16, which is removably attached to a sensor base 15 that is attached to a ceiling surface or the like using a twist lock mechanism, has a light emitting diode and a photodiode (light receiving element) at the bottom, and smoke flows into the sensor body 16. This smoke detection chamber 1 has a smoke detection chamber 17.
A printed board 18 on which the circuit shown in FIGS. 1 and 2 is formed is provided in a partitioned room at the top of the board 7, and a terminal board 19 is provided above the printed board 18.

The electrical connection between the printed board 18 and the terminal board 19 can be made, for example, by installing a column-shaped power terminal 20 on the surface of the printed board 18 by screwing a nut 21 from the back side. , the conductive plate 22 of the terminal board 19 is electrically connected to the power terminal 20 by screwing the screw 23, and the printed board 18 and the terminal board 19
This eliminates the need to use lead wires for electrical connections between the two.

In addition, the switch for shortening the set accumulation time has columnar switch terminals 24 and 25 fixed with screws from the back side of the printed board 18.
A removable conductive fitting 28 is attached to each of the switch terminals 24 and 25 between screws 26 and 27 via a terminal plate 19.

Figure 4 shows the screws 26 and 27 on the terminal plate 19.
This is a plan view of the switch of the present invention shown in FIG.
The switch is turned on when the screws 26 and 27 are connected, and the switch is turned off when the screws 26 and 27 are disconnected as shown at 28'.

With such a switch structure, when the sensor main body 16 is attached to the sensor base 15, the set accumulation time can be set to, for example, 30 seconds by turning off the switch depending on the situation at the installation location. Alternatively, by positioning the switch on, the set accumulation time can be shortened to, for example, 8 seconds.

FIG. 5 shows another embodiment of the switch used in the present invention, in which a pair of conductive screws 29 and 30, which serve as switch terminals, are planted on a printed board 18, and a slidable contact is provided on the terminal board 19 side. A conductor 31 is provided, and the positions where it contacts the screws 29 and 30 are made to protrude by punching to form spring-like contacts 32 and 33, and an operating piece 34 for performing a sliding operation is protruded from the center of the contact conductor 31. The switch is turned on and off by sliding the contact conductor 31.

In this way, the switch shown in Figs. 4 and 5 has the advantage that it has a simple structure, and there is no need to connect a lead wire between the printed board 18 and the switch part, making the assembly work simple and easy. It has the characteristic of being able to

Of course, the switch used in the present invention is not limited to the mechanical structure described above. For example, the switch contacts may be the contacts of a latching relay, and the coil terminal of the latching relay may be protruded to the outside. You can apply a voltage to the terminal from the outside, and for example, excite the primary coil to turn the switch on, and excite the secondary coil to turn it off. Alternatively, you can install a reed switch and attach it to the tip of the operating rod. The switch may be turned on and off by applying a magnetic field from the outside, such as by bringing a magnet close to it.

Another method of electrically turning on and off a switch is to install a transistor that turns on and off by changing the polarity of the power supply voltage applied to the sensor, and use the contacts of the relay operated by this transistor as the switch contacts. Alternatively, turning on or off the switch may be determined by changing the polarity of the power supply.

FIG. 6 is a circuit diagram showing another embodiment of the present invention, taking an ionization type smoke detector as an example.

First, to explain the configuration, it is a diode bridge.
The DB and constant voltage constant current circuit 2 is the same as the embodiment shown in FIG. 1, and includes an internal electrode equipped with a radiation source as a smoke detection means, an intermediate electrode whose potential changes due to changes in ionic current due to inflow of smoke, and An ionization type smoke detection section 35 consisting of an external electrode into which smoke flows is provided, and a field effect transistor 36 is used to extract potential changes in the intermediate electrode due to smoke. The detection signal from the field effect transistor 35 is compared with a reference value set by a variable resistor VR by a comparator 37, and when it exceeds the reference value, the comparator 37 produces an H level output.

The H level output of this comparator 37 is
and R29 to charge the capacitor C14, and the charging voltage of the capacitor C14 is applied to the anode of PUT38 via the resistor R28.
PUT38 becomes conductive when the anode voltage becomes more than a predetermined value than the gate voltage, and the thyristor SCR
The bird supplies a signal to the gate circuit to make it conductive,
An alarm signal is sent to the receiver by conduction of the thyristor SCR.

Therefore, the accumulation time when a fire is detected is determined by the charging time constant of resistors R29 and R30 and capacitor C14, and the charging time constant is set so that the accumulation time is 20 to 60 seconds. are doing.

On the other hand, a switch 5 for shortening the set storage time is provided in parallel with the resistor R29, so that the time constant for charging the capacitor C14 can be reduced.

That is, when the switch 5 is off, the preset accumulation time is reached, but when the switch 5 is turned on, the resistor R29 is short-circuited, the charging time constant becomes smaller, and the charging time of the capacitor C14 until the PUT 38 is turned on is reduced. is shortened, and the setting storage time is shortened.

The switch structure of the switch 5 used in the embodiment of FIG. 6 is the same as the above-described switch structure shown in the embodiment of FIG.

As explained above, according to the present invention, in an accumulation-type fire detector, the set count number of the counter or the charging time constant can be changed in the sensor body to shorten the set accumulation time. Since a switch is provided for conversion, when installing a storage type fire detector, it can be changed according to the situation at the site.
The setting accumulation operation time can be shortened simply and easily, and the operating conditions of the fire detector can be adapted to the installation location.

Furthermore, since the structure of the switch is simple, it has the advantage that the cost of the sensor itself is hardly affected and the reliability of the switch is high.

Furthermore, if maintenance and inspection are performed with the switch turned on and the set storage time shortened, the time required for maintenance and inspection can be reduced and work efficiency can be improved.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the present invention in the example of a photoelectric storage type fire detector; Fig. 2 is a block diagram showing the configuration of an IC in the embodiment of Fig. 1; Figure 3 is a cross-sectional view of a sensor showing one embodiment of the switch structure used in the present invention, and Figure 4 is a cross-sectional view of a sensor showing an example of the switch structure used in the present invention.
FIG. 5 is a partial cross-sectional view showing another embodiment of the switch structure used in the present invention, and FIG. 6 is an example of an ionization type storage smoke detector. FIG. 3 is a circuit diagram showing another embodiment of the present invention. 1, 1'... terminal, 2... constant voltage circuit, 3...
IC, 4, 14, 37... Comparator, 5... Switch, 6... Master clock, 7, 10... Counter, 8, 11... One shot multi, 9, 1
2...Amplifier, 13...Flip-flop, 15
...Sensor base, 16...Sensor body, 17...
... Smoke detection chamber, 18 ... Printed board, 19 ... Terminal board, 20 ... Power terminal, 21 ... Nut, 22 ...
...Continuity piece, 23, 26, 27, 29, 30...Screw, 24, 25...Switch terminal, 28...Continuity fitting, 31...Contact conductor, 32, 33...Contact, 34...Operating piece , 35... Ionization type smoke detector, 36... Field effect transistor, 38...
PUT, R1-R33...Resistance, VR...Variable resistor, SCR...Thyristor, DB...Diode bridge, D1-D3...Diode, ZD1-ZD
4... Zener diode, C1 to C15... Capacitor, LED... Light emitting diode, PD... Photo diode.

Claims (1)

[Scope of claim for utility model registration] A fire detection unit that outputs a fire output when a change in physical phenomena due to a fire exceeds a predetermined value, and when the fire output from the fire detection unit continues for a set accumulation time. A fire detection system comprising: a storage circuit that outputs an output to the storage circuit; an alarm circuit that is activated by the output of the storage circuit to send out a warning signal; and a switch means that shortens the set storage time of the storage circuit. vessel.