JPH0421183Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a dimming type smoke detector for monitoring the presence or absence of smoke over a relatively long distance.

[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. It is often advantageous to use dimming smoke detectors that can see over long distances. However, in this method, the distance between the light emitting and receiving parts is long, and the current consumed by the light emitting element is much larger than in the light scattering type or ion type.In addition, the light receiving part also requires a considerable amount of circuitry to measure and judge the light attenuation rate. Since the sensor consumes a large amount of current, it cannot be connected to conventional receivers connected to light scattering or ion smoke detectors, and a receiver with a large current capacity is required.

[Purpose of the invention] This invention was created in view of the above problems.
By intermittently supplying power to the light emitter and supplying the light receiver with constant voltage from the intermittent power supplied to the light emitter, current consumption can be reduced, making it possible to reduce current consumption and reduce the power consumption of conventional fire alarms. The purpose of this is to provide a dimming type smoke detector that can be connected to a smoke detector, and its second purpose is to solve the problem that it takes time to make adjustments during test runs. be.

[Disclosure of the invention] The attenuation type smoke detector of the present invention detects the presence or absence of smoke in the optical path by installing the light emitting part and the light receiving part separately and measuring the attenuation rate of the received light beam. In dimming type smoke detectors, a capacitor is charged by a power supply current supplied from the receiver side through a signal line, and a pulsed power supply current is transmitted from the capacitor to the light emitter through a switching element controlled by an intermittent oscillation circuit. providing a means for supplying a constant voltage of the pulsed power supply current via a constant voltage circuit to the light receiving unit, and switching the pulse repetition cycle of the intermittent oscillation circuit to a cycle shorter than that during monitoring; When the pulse repetition period is set to a shorter period than during monitoring, a battery is connected in parallel with the above capacitor, and power is intermittently supplied to the emitter, and power is intermittently supplied to the receiver. The current load on the receiver side is reduced by supplying the power supplied to the device at a constant voltage, and the pulse repetition period can be changed to a shorter period than during monitoring. By connecting the battery in parallel with the capacitor, the light emission interval of the light emitting part becomes shorter and the power consumption increases. First, it allows power to be supplied from the battery so as not to place a burden on the receiver.

FIG. 1 shows an embodiment of the dimming type smoke detector of the present invention. In the same figure, the power supply current (several mA) supplied from receiver 1 through signal line 2
supplies charging current to the capacitor _C1 via the constant voltage circuit 3 and the constant current circuit 4. Reference numeral 5 denotes an intermittent oscillation circuit, which supplies a pulsed power supply current from the capacitor _C1 to the light emitter 7 and the light receiver 8 by generating a pulse with a width of several tens of mS every 5 seconds and controlling the switching element 6. be done. The constant voltage circuit 9 is for making the voltage of the power supplied to the light receiving section 8 constant during this short pulse period.

Figure 2 shows the main part of Figure 1 in a concrete circuit.In the intermittent oscillation circuit 5, the charge of capacitor _C2 is discharged through _R1 or _R2 , which has a large resistance value, and the voltage of capacitor _C2 decreases. When the output of the comparator IC becomes H level, charging of the capacitor _C2 is started through the resistor _R5 , and when the switch 11 is turned to the contact b side,
As shown in FIG. 4b, a pulse having a pulse width T ₁ determined by a resistor R ₅ and a capacitor C ₂ and a repetition period T ₂ determined by a resistor R ₁ and a capacitor C ₂ is generated,
By applying this pulse to the base of the switching element 6 made of a Darlington transistor, the discharge current of the capacitor _C1 is supplied to the light projecting section 7 and the light receiving section 8 as a power supply current.

The switch 11 in FIG. 2 is for switching the pulse repetition period T ₂ , and connects the battery 10 in parallel with the capacitor C ₁ in conjunction with the switch 12 in FIG. 1, and simultaneously switches the pulse repetition period T ₂ . Shorten it as shown in Figure 4a,
As a result, during a test run, current is supplied from the battery 10 to shorten the light emitting period of the light emitting element, thereby making it possible to perform adjustment work quickly.

In the embodiment shown in FIG. 3, in the intermittent oscillation circuit 5, the repetition period _T2 is determined by the resistor _R1 or _R2 ,
The pulse width _T1 is determined by turning on the transistor Q with a completion signal issued from the light receiving section 8 when the light emitting/receiving operation and signal processing are completed, and lowering the voltage of the capacitor _C2 . Note that when smoke is detected, the SCR 13 is activated by the detection signal output from the light receiving section 8, and the signal line 2 is activated.
The receiver 1 is notified by short-circuiting.

In the configuration of FIG. 2 or 3, if the emitter 7 and the light receiver 8 consume 100 mA, for example, by supplying a pulse current with a width of 20 to 30 mS every 5 seconds, the receiver 1 The power supply current from the sensor can be suppressed to a few hundred microamperes, so it can be sufficiently supplied by a receiver such as a conventional fire detector. Note that the microprocessor clock used in the light receiving signal amplification circuit and judgment circuit takes several milliseconds to stabilize after the power is turned on.
Since 10 mS is required, it is advantageous to delay the emission of the optical pulse from the light projector by at least 10 mS after power is supplied.

[Effect of the invention] As mentioned above, in the light emitting/receiving sensor of the present invention,
The light emitting part and the light receiving part are installed separately, and the presence or absence of smoke in the optical path is detected by measuring the attenuation rate of the received light beam, and the power is supplied from the receiver side through the signal line. A capacitor is charged by the current, a pulsed power supply current is supplied from the capacitor to the light emitter through a switching element controlled by an intermittent oscillation circuit, and the pulsed power supply current is made into a constant voltage through a constant voltage circuit. Since this voltage is supplied to the light receiving part, the supply current to the receiver side can be reduced, and as a result, there is an advantage that a large number of sensors can be monitored simultaneously on the receiver side. Not only can sufficient current be supplied to the light emitting element even when the light emitter and light receiver are installed 100 meters apart from each other in a tunnel, but it also provides sufficient power for complex circuits using microprocessors, etc. Even though the power supply current is saved by lengthening the interval between light emitting and receiving operations, a means is provided to switch the pulse repetition period of the intermittent oscillation circuit to a shorter period than during monitoring, and the pulse repetition period can be reduced. Since a battery is connected in parallel with the capacitor when the cycle is set to be shorter than that during monitoring, by switching the pulse repetition cycle to a cycle shorter than that during monitoring, the light emission can be prevented during a trial run of the smoke detector. Adjustment work can be done quickly by shortening the light emission interval of the receiver, and at the same time, by connecting a battery in parallel with the capacitor and using the battery as a power source, the load on the receiver is increased. It has the effect of not having any.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram showing one embodiment of the present invention, FIG. 2 is a specific circuit diagram of the main part of the same as above, FIG. 3 is a specific circuit diagram of main part of another embodiment of the same as above, and FIG. This is a time chart showing the same operation as above. 1 is the receiver, 2 is the signal line, 3 is the constant voltage circuit, 4
is a constant current circuit, 5 is an intermittent oscillation circuit, 6 is a switching element, 7 is a light emitter, 8 is a light receiver, 9 is a constant voltage circuit, 10 is a battery, 11 and 12 are switches, 13 is an SCR, C ₁ C ₂ is a capacitor, Q is a transistor, R ₁ to _{R 7} are resistors, D is a diode, IC
is a comparator.

Claims (1)

[Scope of utility model registration request] In a dimming type smoke detector, which detects the presence or absence of smoke in the optical path by arranging the emitter and receiver separately and measuring the attenuation rate of the received light flux, A capacitor is charged by the power supply current supplied from the capacitor, a pulsed power supply current is supplied from the capacitor to the light emitter through a switching element controlled by an intermittent oscillation circuit, and the pulsed power supply current is passed through a constant voltage circuit. A means is provided for supplying a constant voltage to the light receiving section through the intermittent oscillation circuit and switching the pulse repetition period of the intermittent oscillation circuit to a period shorter than that during monitoring, and when the pulse repetition period is set to a period shorter than that during monitoring. A dimming type smoke detector consisting of a battery connected in parallel with the above capacitor.