JPS5812125Y2 - Alarm display circuit for gas detector - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an alarm display circuit for a gas detector.

In general, gas detectors are those that generate an alarm signal when the gas concentration exceeds a certain level, as well as an alarm signal indicating a break in the sensor, a break in the cable connecting the sensor and the receiving circuit, etc. Vehicle is heavy 0 An object of the present invention is to provide a suitable alarm display circuit with a simple configuration for use in this type of gas detector.

The present invention will be explained below with reference to the drawings.

The figure is an electrical connection diagram showing one embodiment of the device of the present invention.

In the figure, 1 is a power supply, 2 and 3 are switches that are closed in the event of an abnormality such as a disconnection of a sensor (not shown) or a cable (not shown), and 4 is a switch that is connected to these switches 2 and 3 at one end and the other end. This is a relay connected to power supply 1.

5 is an input terminal to which a signal corresponding to the gas concentration is given; 6
, 7 is the normally closed connection ACP of relay 4, and the power supply 1 is connected via a.
The relays 8.9 connected to the relays 8.9 are circuits (hereinafter simply referred to as excitation means) as excitation means for the relays 6.7, respectively.

The excitation means 8 is composed of a transistor Tr1 connected between one end of the relay 6 and a common point, and a differential amplifier A that makes the transistor Tr1 conductive when the input signal is constant and exceeds a level E. There is.

The excitation means 9 connected between the relay 7 and the common point includes a series circuit of the resistor R1 and the normally closed contact CP61 of the relay 6, a capacitor C connected in parallel to this series circuit, and a capacitor C connected in parallel to the series circuit. Normally open contacts op of relay 6 connected in series in a parallel circuit 6. It is made up of.

10 is a release switch connected in series with the self-holding normally open contact 0P71 of the relay 7 and connected in parallel to the excitation means 9;
11 is connected to the power supply 1 through the normally open contact 0P62fc of the relay 6 or through a series circuit of the normally closed contact CP 62 of the relay 6 and the normally open contact OP 72 of the relay 7 so that its driving current is shut off. light emitting diode, 12
is a light emitting diode connected so that its driving current flows from the power source 1 through a series circuit of the normally closed contact CP62 of the relay 6 and the normally closed contact CP72 of the relay 7.

In addition, 13 is a light emitting diode 11 and 12 when the relay 4 is energized or when the relay 7 is energized.
This is a brushing control circuit that intermittently cuts off the drive current flowing through the brush.

In this brushing control circuit 13, Tr2 is a transistor whose collector terminal is connected to the diode 11 and 12 through the resistor R2, whose emitter terminal is connected to the common point, and whose base terminal is connected through the resistors Ra and 'r. Power supply 1
It is connected to the.

For example, U is a pulse oscillator that outputs a square wave with a repetition period of about 1 second, OP4 is a normally open contact of relay 4, 0P73
is the normally open contact of relay 7.

These contacts OP 4 e OP 73 are transistors T
In parallel to the pressure between the base terminal of rz and the output terminal of oscillator U,
connected so that

The low level voltage of the output of the p1 oscillator U is lower than the common point voltage.

The operation of the device of the present invention configured as described above will be explained.

First, a case will be described in which there is no abnormality in the sensor or cable and the signal indicating the gas concentration is constant and does not exceed the bell E'r.

At this time, relay 4.6.7 is not energized.

Therefore, the contacts CP62tCP71 become conductive.

On the other hand, a base current is always supplied to the transistor 'I'r2 through the resistor R3't.

Therefore, in this case, the light emitting diode 12 lights up continuously.

Next, a case will be described in which there is no abnormality in the sensor or cable, but the signal indicating the gas concentration remains constant and exceeds Bell E.

At this time as well, relay 4 is not energized.

However, relay 6 is energized, which causes current to temporarily flow through capacitor C, energizing relay 7, and relay I is self-held at its contact CP71.

Therefore, the contact 0P62 becomes conductive. On the other hand, the contact 0P73 also becomes conductive, and the base current is intermittently supplied to the transistor Tr2.

Therefore, in this case, the light emitting diode 11 lights up intermittently (hereinafter this state will be referred to as blinking).

In this case, if the release switch 10 is opened, the light emitting diode 11 will light up continuously.

If the gas leakage point is repaired after this gas leakage check operation, the gas concentration will drop and the relay 6 will be de-energized.
lights up.

After confirming this, if you close the release switch, you can return to the normal state.

Finally, we will discuss the case where an abnormality occurs in the sensor or cable.

At this time, since the relay 4 is energized, the relays 6 and 7 are de-energized regardless of the magnitude of the gas concentration.

Therefore, the contact CP 62 s CF3I becomes conductive.

On the other hand, the contact ωP4 becomes conductive, and the transistor Tr2
Base current is intermittently supplied to.

Therefore, in this case, the light emitting diode 12 blinks.

In the above embodiment, light emitting diodes 11 and 12 are used as light emitting elements, but incandescent lamps or the like may be used.

Further, it is advantageous in terms of space if a two-color light emitting element is used as the light emitting element.

As explained above, according to the present invention, an alarm display circuit can be realized with a simple configuration that can display not only alarms indicating that the gas concentration has exceeded a certain value, but also alarms indicating abnormalities in sensors, cables, etc. can.

[Brief explanation of the drawing]

The figure is an electrical connection diagram showing one embodiment of the device of the present invention. 1...Power supply, 2,3...Switch, 4,6.7...
・Relay, 5...input terminal, 8, 9...excitation means,
10... Release switch, 11.12... Light emitting diode, 13... Flat sink circuit.

Claims (1)

[Claims for Utility Model Registration] A gas detector consisting of a detection section including a sensor and a reception circuit, comprising means for detecting a disconnection of the sensor or a disconnection of a cable between the detection section and the reception circuit, and excitation by the detection signal. a second relay connected so that its excitation current flows through a normally closed contact of the first relay, a second relay excitation means for exciting the second relay, and the first relay. A third relay connected so that its excitation current flows through a normally closed contact, a third relay excitation means for exciting the third relay, and a series circuit with a self-holding normally open contact of the third relay. and a release switch connected in parallel to the third relay excitation means. a first light emitting element connected such that its drive current flows through a normally open contact of the second relay or through a series circuit of a normally closed contact of the second relay and a normally open contact of the third relay; , the normally closed contact of the second relay and the third relay.
a second light emitting element connected in such a way that its drive current flows through a series circuit with a normally closed contact of the relay; The brushing control circuit includes a brushing control circuit that intermittently cuts off the driving current flowing to the first and second light emitting elements, and when the gas concentration exceeds a certain level, the second light emitting element
An alarm display circuit for a gas detector configured to operate a relay excitation means and operate the third relay excitation means for a certain period of time after the start of the operation of the second relay excitation means.