JPH0537359Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Technical Field> This invention relates to a transmitter circuit for a flame alarm.

<Prior art> Fig. 2 is a circuit diagram of a conventional flame alarm. When the flame detector DT is activated by flame, the district relay N of the receiver CP is activated, and its contact n1 is closed, so that the operation is automatic. Retained. Also another contact n2
is closed and flame alarm relay F is activated.

Meanwhile, the person who discovered the flame was the nearest transmitter.
When pushbutton switch PB of MB is pressed, district relay N and relay F operate in the same way as when flame detector DT operates. Furthermore, the other contacts of the pushbutton switch PB are also closed, and the contact f of the relay F
is closed, relay M operates and its contacts
m1 and m2 are closed and relay M is self-maintained.
By closing this contact m2, and assuming that the line between the transmitter MB and the receiver CP is short and the line resistance Rl is approximately zero ohm, the power supply voltage E will be applied to the response indicator La. If the power supply voltage is 24V and an incandescent lamp with a rated voltage of 24V and a rated current of 30mA is used as the response indicator La, each response indicator
A current of 30mA flows through the lamp, for a total of 60mA, and it lights up brightly.

<Problems with the Prior Art> Providing two lamps in this way increases the current consumption, but even if one incandescent lamp breaks, the remaining one remains on to display the lighting.

However, if the contact with the lamp socket is poor, or if you do not notice that both wires are broken, the relay M will not operate, and the fire hydrant pump etc. that operate through that contact will not be activated in an emergency. It was hot.

For this reason, as shown in Figures 3 and 4, an oscillation circuit that uses a light emitting diode as an indicator light, which is almost free from failures such as disconnection, and is combined with a constant current load or a switching circuit to reduce current consumption. However, it has been proposed in Japanese Patent Application No. 62-23630 and Utility Application No. 14825.

However, in the case shown in Figure 3, the rising voltage of the light emitting diode LED, which also serves as the reference voltage element, varies greatly from 1.7V to 2.4V.
When a constant current circuit designed for 1.7V is used with a reference voltage of 2.4V, the collector loss of transistor Q31 becomes large, so it was necessary to take this into account and select a transistor that can withstand high power consumption.

Furthermore, in the device shown in FIG. 4, the relay M is operated when the transistor Q41 is turned on, and the light emitting diode LED is lit with a constant current when the transistor Q42 is turned on. However, due to external noise etc., the relay M is operated. If transistor Q41 were to operate before transistor Q41, there was a risk that relay M would not operate.

<Means for solving the problem> In consideration of the above points, this invention aims to obtain a transmitter circuit for a flame alarm using a long-life light emitting diode, which consumes even less current than the previously proposed one. The transmitter's push-button switch, current-limiting resistor, light-emitting diode, and reverse connection prevention diode are connected in series with the relay that detects the operation of the transmitter. A first transistor is provided in parallel to the series circuit of the relay and the light emitting diode, the relay and the push button switch are connected in series, and the first transistor is turned on when the switch is closed and causes a predetermined current equal to or higher than a current value to flow through the relay. and a second transistor provided with a delay means so as to become conductive after the voltage drop occurring in another part of the current limiting resistor exceeds a predetermined value and the relay is activated, and the second transistor is brought into conduction. A third transistor is provided which conducts accordingly and controls conduction of the first transistor.

<Function> Since this device is constructed as described above,
The relay operates reliably by being supplied with a predetermined current greater than the current value through the first transistor. Further, when the relay is self-held and the response indicator light is directly connected to the power source, the first transistor is turned off, and a predetermined current is applied to the light emitting diode as the response indicator light via the current limiting resistor. The flow is brightly lit.

<Embodiment> An embodiment of the transmitter circuit of the flame alarm of this invention will be described below with reference to FIG.

In the figure, CP is the receiver, N is the district relay,
F is a flame alarm relay, M is a manual display relay, and relay N is a flame detector DT and transmitter MB.
Push button switch PB and relay F are connected to make contact n2 of relay N, respectively. In addition, the manual display relay M is a push button switch PB of the transmitter MB, a switching circuit S to be described later,
Light emitting diode LED, diode DA, DM,
It is connected to the positive and negative power terminals through the make contact f of the relay F.

The switching circuit S is a push button switch
Resistor as current limiting resistor connected in series with PB
A first transistor Q1 whose collector and emitter are connected in parallel to a series circuit of R1, R2 and a light emitting diode LED, a series circuit of a resistor R2 and a light emitting diode LED, and a resistor connected in parallel to the resistor R1.
A second transistor Q2 with a capacitor C as a delay means whose base is connected to the connection point of the resistors R3 and R4 of the series circuit of R3, R4, and R5 is connected in parallel to the series circuit of the resistor R1 and the transistor Q1. It consists of a resistor R6 and a series circuit of a third transistor Q3.

The base of transistor Q1 is connected to the collector of transistor Q3, the collector of transistor Q2 is connected to the base of transistor Q3 through resistor R7, and the emitter of transistor Q3 is connected through resistors R7 and R8.

Next, the operation of the above circuit will be explained.

When the current value of the relay M is set to 15.4 mA, a margin of 10% is taken to allow a current of 16 mA or more to flow to ensure reliable operation. In addition, the power supply voltage shall be at least 20.4VDC and the external wire resistance shall be 50Ω.

When the transmitter MB is pressed and the button switch PB is pressed, the district relay N is operated and the contact n1 is closed and self-maintained. Further, the contact n2 is closed, and the relay F is operated, and the contact f is closed.

As a result, transistor Q1 includes push button switch PB, resistor R6, diodes DA, DM,
Base current I _QIBE flows through relay M and contact f, turning on transistor Q1. When the transistor Q1 is turned on, a current I _M higher than the current value flows through the relay M through the push button switch PB, the resistor R1, the transistor Q1, the diodes DA and DM, and the contact f.

That is, the relay M is 920Ω, the resistor R1 is 68Ω, and the resistance
Assuming that R6 is 5.1KΩ, 0.7V between the base and emitter of diodes DA and DM and transistor Q1, and 0.1V between the emitter and collector of transistor Q1, I _Mnio = 20.4 [V] - 0.7 [V] - 0.7 [V] 〕−0.1〔V
] / 920 [Ω] + 50 [Ω] + 68 [Ω] = 18.2 [mA] I _QIBE = 18.2 [mA] × 68 [Ω] + 0.1 [V] - 0.7 [V]
] / 5.1 [KΩ] = 125 [μA] Therefore, if hfe of transistor Q1 is 200, I _QICE / I _QIBE = 18.2 [mA] / 125 [μA] = 146 < 200, and transistor Q1 is fully turned on.

As a result, a predetermined voltage is generated across the resistor R1, and the voltage drop across the resistor R3 becomes a predetermined voltage, e.g., 0.6 V or more, which turns on the transistor Q2 after the relay M operates due to the delay effect of the capacitor C.
Since transistor Q3 is turned on, transistor Q3 does not operate before transistor Q1, and henceforth, the base current of transistor Q1 is limited by the joint operation of transistors Q1, Q2, and Q3.
held at a constant current.

That is, if resistors R3 and R4 are 47KΩ, resistor R5 is 10KΩ, and the current flowing through resistor R1 is I _R1 , I _R1nio = 0.6 [V] + 0.6 [V] / 47 [KΩ]
× (47 [KΩ] + 10 [KΩ] / 68 [Ω] = 19.5mA Even for safety reasons I _R1nio ×0.9 = 17.6 [mA] > I _Mnio ×0.9 = 16.4 [mA]
>15.4 [mA] (the impressive current of relay M), and relay M operates reliably.

When relay M operates, resistance R9, contacts m1, f
Through this, the relay M is self-maintained. Also the contact
By closing m2, the power supply voltage is directly applied to the transmitter MB, but from then on, transistors Q1,
The current is maintained at a constant level by the joint operation of Q2 and Q3.

As a result, the light emitting diode LED flows through the pushbutton switch PB, resistors R1 and R2, diode DA and contact m2, and is illuminated brightly. That is, if the maximum current flowing through the light emitting diode LED at this time is I _LED(nax) , then I _LED(nax) = 26.4 [V] - 0.7 [V] - 1.9 [V] 68 [
Ω〕＋
1.2 [KΩ] = 18.8 [mA]. Also, the current flowing through resistor _R6 and the current flowing through the base and emitter of transistor Q3 are 5.04 [mA] and 2.50 [mA], respectively.
Therefore, the current flowing through the diode DA is I _DA(nax)
=I _LED(nax) +I _R6(nax) +I _Q3BE(nax) = 26.3 [mA], which is sufficiently smaller than that of the conventional method.

<Effects> Since the transmitter circuit of this invention is configured and operates as described above, it has almost no disconnection, consumes less current than the conventional one, and operates more reliably than the previously proposed one. This has the effect of providing a transmitter circuit for an alarm.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the transmitter circuit of the flame alarm of this invention, FIG. 2 shows a conventional transmitter circuit, and FIGS. 3 and 4 show the previously proposed transmitter circuit. CP...Receiver, N...District relay, F...Flame alarm relay, M...Manual display relay, DT
...Flame detector, MB...Transmitter, PB...Push button switch, S...Switching circuit,
LED...Light emitting diode, DA, DM...Diode, R1, R2...Current limiting resistor, R3 to R9...
Resistor, Q1, Q2, Q3...transistor.

Claims (1)

[Scope of utility model registration request] A push button switch of the transmitter, a current limiting resistor, a light emitting diode and a diode for preventing reverse connection are connected in series with a relay that detects the operation of the transmitter. A first transistor is provided in parallel to the series circuit, the relay and the push button switch are connected in series, and the first transistor is turned on when the switch is closed and causes a predetermined current higher than the current value to flow through the relay, and further the current limiter is configured to limit the current. a second transistor provided with a delay means so as to become conductive after the voltage drop occurring in the other part of the resistor exceeds a predetermined value and the relay is activated; a third transistor that controls conduction of the first transistor;
A transmitting circuit for a flame alarm, characterized in that a transistor is provided.