JPH0548517B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention detects the presence or absence of smoke by arranging a light emitting part and a light receiving part separately and measuring the light attenuation rate in the optical path. This invention relates to a dimming type separate smoke detector.

[Background technology] In general, in large areas where smoke easily spreads, such as in tunnels, large warehouses, or building exhaust ducts, it may be difficult to detect fires early with light scattering type or ion type smoke detectors. In many cases, it is more advantageous to use a dimming-type separate smoke detector that can see over a long distance by arranging the light emitting part and the light receiving part separately. However, in this type of smoke detector, the distance between the light emitting part and the light receiving part is long, so the current consumed by the light emitting element is much larger than in the light scattering type or ion type. .

On the other hand, smoke detectors are connected to a receiver via a signal line, and when the smoke detector detects the presence of smoke, a detection signal is transmitted to the receiver to notify the receiver of the occurrence of a fire, etc. It is becoming more and more common. Further, operating power for the smoke detector is supplied from the receiver via a signal line. However, since dimming type separate smoke detectors consume more current than light scattering and ion type smoke detectors, they are connected to light scattering and ion type smoke detectors. There is a problem in that the conventional receiver cannot be used in a dimming separation type sensor because it cannot supply sufficient power.

[Object of the Invention] The present invention has been made in view of the above-mentioned problems, and its purpose is to reduce current consumption and to be compatible with conventionally provided receivers with small current capacity. The present invention aims to provide a dimming type separate type smoke detector that can be connected.

[Disclosure of the Invention] The dimming type separate smoke detector of the present invention has a light emitting part and a light receiving part installed separately, and detects the presence or absence of smoke by measuring the light attenuation rate in the optical path. In a separate type smoke detector, there is a non-polarization circuit connected between the signal lines to transmit the detection signal to the receiver, and a power supply that is supplied from the receiver side through the signal line and passed through the non-polarization circuit. A first constant voltage circuit that supplies a circuit power supply by constant voltage, a constant current circuit that constant current outputs the output of the first constant voltage circuit, and a capacitor that is charged with a constant current output from the constant current circuit. , a second constant voltage circuit that supplies power to the light receiver, a switching element inserted between the light emitter, the second constant voltage circuit, and the capacitor; The device is equipped with a switch control circuit that makes the switching element conductive for a short period of time with a repetition period of By intermittently supplying power to not only the optical part but also the light receiving part, which includes the light receiving signal amplification circuit and the light attenuation rate determination circuit, using pulsed current, the current burden on the receiver side can be significantly reduced. It has been reduced.

FIG. 1 shows an example of a dimming type separate smoke detector of the present invention. In the figure, _the power supply current ( _several
mA) supplies voltage (approximately 12V) to the switch control circuit E via the non-polarization circuit A and the constant voltage circuit B, and further supplies the voltage (approximately 12 V) to the switch control circuit E via the constant current circuit _C.
A constant charging current is supplied to the capacitor C1, and from the point when the charging voltage of the capacitor _C1 reaches a certain value, it is controlled by the switch control circuit E to conduct for short periods (approximately 20 mS) at a constant repeating cycle. The switching element D supplies a pulsed discharge current from the capacitor _C1 to the light projecting section _L1 including the light emitting element. In addition, the discharge current of the capacitor _C1 is supplied as a pulse current to the light receiving section _L2 , which includes a light receiving element and a light receiving signal amplification circuit, and the judgment section L3, which includes a microprocessor, via a constant voltage circuit F _{(approximately 5} V). . Conventional dimming type separate smoke detectors were not equipped with a non-polarization circuit A because they could not be connected to a receiver due to current capacity, but in this embodiment, a non-polarization circuit A was provided. This makes it possible to connect to signal lines a ₁ and a ₂ without worrying about connection polarity. That is,
By providing the non-polarizing circuit A, incorrect connections can be prevented. Also, since capacitor C ₁ is charged through constant current circuit C, after the charging voltage of capacitor C ₁ reaches a certain value, if there is no change in the load, the capacitor will be
Since the fluctuation range of the terminal voltage of C ₁ is constant,
This makes it possible to stabilize the power supply to the light projecting section L ₁ , the light receiving section L ₂ , and the determining section ₃ by the capacitor C ₁ .

Figure 2 shows the main part of Figure 1 in a concrete circuit.In switch control circuit E, a comparator detects when the charging voltage of capacitor _C1 has reached a certain value.
When IC ₁ detects and turns on transistor Q ₅ , op-amp IC ₂ starts working, and when the voltage of capacitor C ₂ charged through resistor R ₅ exceeds the threshold of op-amp IC ₂ , the output of op-amp IC ₂ turns on. Inverted transistor Q ₃ and Darlington circuit Q ₁ ,
Switching element D consisting of _Q2 is made conductive.
This causes the discharge current of capacitor C ₁ to
When power is supplied to L ₁ , light receiving section L ₂ , and judgment section L ₃ and the light emitting/receiving operation and signal processing are completed, the judgment section L ₃
Transistor Q ₄ is turned on by the completion signal from , lowering the voltage of capacitor C ₂ and switching element D
Turn off. In this way, capacitor _C1 starts charging again. When smoke is detected, the thyristor T is activated by the detection signal outputted from the determining section _L3 , and the receiver is notified by shorting the signal lines _a1 and _a2 .

Figure 3 shows the above operation as a time chart. When the voltage on capacitor C ₁ reaches the threshold value Vt ₁ , the output of comparator IC ₁ is inverted, turning on transistor Q ₅ , and turning on transistor Q ₅ . Charging will start. When the voltage of the capacitor C ₂ reaches the threshold value Vt ₂ after about 5 seconds, the output of the operational amplifier IC ₂ is inverted to H level, turning on the switching element D, and the light emitting part L ₁ , from the capacitor C ₁ . Light receiving part L ₂ ,
Power is supplied to the judgment unit _L3 . After about 20mS, a pulse signal indicating the end of processing is sent from judgment unit _L3 to the transistor.
When the signal is sent to _Q4 , transistor _Q4 turns on, inverts the output of operational amplifier _IC2 to L level, and turns off switching element D. The charging time of capacitor C ₁ is set to be slightly shorter than the charging time of capacitor C ₂ so that the voltage of capacitor C 1 does not fall below the threshold value Vt ₁ at all times. For example, if the emitter L ₁ , light receiver L ₂ , and judge L ₃ consume 100 mA, a pulse current of 20 mS width will be supplied every 5 seconds, reducing the power supply current from the receiver. The current can be kept to a few hundred microamperes, which is sufficient for conventional receivers. Note that it takes several milliseconds for the light receiving signal amplification circuit and microprocessor clock to stabilize after the power is turned on.
Light pulses are emitted from the light emitter _L1 after power is supplied.
Delay by at least 10mS. In other words, the light emitting section L ₁ is caused to emit light after a period of time has elapsed since the start of the pulse current supply until the operations of the light receiving section L ₂ and the determining section L ₃ become stable. With the above configuration, sufficient power can be supplied even to a complex circuit using a microprocessor, etc., and since power supply current is supplied periodically, memory backup can be easily performed using a capacitor.

[Effects of the Invention] As described above, in the attenuation type separation type smoke detector of the present invention, a depolarization circuit connected between the signal lines for transmitting the detection signal to the receiver, and a signal line A first circuit that supplies circuit power by converting the power supplied from the receiver side through the non-polarized circuit into a constant voltage.
a constant voltage circuit, a constant current circuit that converts the output of the first constant voltage circuit into a constant current, a capacitor that is charged with a constant current output from the constant current circuit, and a second constant voltage that supplies power to the light receiving section. The circuit, the light emitter and the second
A switching element inserted between the constant voltage circuit and the capacitor, and a switch control circuit that conducts the switching element for short periods at a fixed repetition period from the time when the charging voltage of the capacitor reaches a fixed value, Power is supplied from the capacitor to the light emitter and the second constant voltage circuit during the conduction period of the switching element, and power is intermittently supplied to the second constant voltage circuit that supplies power to the light receiver and the light emitter. This has the advantage that the power supply current supplied from the receiver side can be minimized, and the receiver side can monitor many smoke detectors simultaneously. This has the advantage that a dimming type separate smoke detector can be used by using a receiver with a small current capacity for connecting the detector. Furthermore, even when the light emitting part and the light receiving part are installed at a distance of 100 m from each other in a tunnel, for example, sufficient current can be supplied to the light emitting part.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing one embodiment of the present invention, FIG. 2 is a specific circuit diagram of the main parts of the same, and FIG. 3 is a time chart showing the operation of the same. a ₁ and a ₂ are signal lines, A is a non-polarization circuit, B is a constant voltage circuit, C is a constant current circuit, D is a switching element, E is a switch control circuit, F is a constant voltage circuit,
C ₁ , C ₂ are capacitors, T is thyristor, Q ₁ to _{Q 7}
are transistors, R ₁ to R ₁₁ are resistors, ZD is a Zener diode, IC ₁ is a comparator, IC ₂ is an operational amplifier, L ₁ is a light emitter, L ₂ is a light receiver, and L ₃ is a judgment unit.

Claims (1)

[Claims] 1 To transmit a detection signal to the receiver in a dimming type separate smoke detector that detects the presence of smoke by installing the light emitting part and the light receiving part separately and measuring the light attenuation rate in the optical path. a non-polarization circuit connected between the signal lines, and a first constant voltage circuit that supplies circuit power by constant voltage of the power supplied from the receiver side through the signal line and passed through the non-polarization circuit; A constant current circuit that makes the output of the first constant voltage circuit a constant current, a capacitor that is charged with a constant current output from the constant current circuit, a second constant voltage circuit that supplies power to the light receiving section, and a light emitter. and a switching element inserted between the second constant voltage circuit and the capacitor, and a switch control circuit that makes the switching element conductive for short periods at a constant repetition period from the time when the charging voltage of the capacitor reaches a certain value. What is claimed is: 1. A dimming type separable smoke detector, characterized in that power is supplied from a capacitor to a light emitting part and a second constant voltage circuit during a conduction period of a switching element.