JPH0210449Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a gas detection and alarm device powered by a commercial AC 100V that issues an alarm when the power is cut off.

Conventionally, this type of gas detection alarm device used for general homes or stores uses commercial AC 100V as a power source, so the device is used by being connected to an outlet.

Figure 1 is a block diagram showing an example of a conventional gas detection/alarm device.
AC100V AC power is converted to a specified DC power supply voltage by power supply circuit 1 and applied to other circuits to enable gas detection.When gas detection circuit 2 detects gas, oscillation circuit 3 is activated. A piezoelectric buzzer 4 provided as an alarm is driven to issue an alarm.

However, with this kind of gas detection alarm device,
For example, if the outlet is unplugged due to a child's mischief, or if the power supply is cut off due to disconnection of wiring or a power outage, the function will stop and gas detection will become impossible.

Even in such a case, if it is determined that the power has been cut off, it is possible to take appropriate measures such as plugging in an outlet.

The present invention was developed by focusing on these conventional problems. When the AC power is cut off, the capacitor that is constantly charged by the AC power source is switched to the alarm side, and the capacitor is charged. To solve the above-mentioned problems by issuing an alarm by energizing an alarm device with a voltage, thereby making it possible to notify a power outage without requiring a built-in emergency power source such as a dry battery.

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

FIG. 2 is a block diagram showing the basic configuration of the present invention. First, to explain the configuration, 1 is a power supply circuit;
2 is a gas detection circuit; 3 is an oscillation circuit that is activated by the detection output of the gas detection circuit 2 to generate an oscillation output of frequency 1; and 4 is a piezoelectric buzzer driven by the output of the oscillation circuit 3.

In addition to this circuit configuration, according to the present invention, the power switching circuit 5
The oscillation frequency 2 is energized by applying a charging voltage by switching the capacitor 6 that is constantly charged via the
An oscillation circuit 7 is provided.

Its operation is such that when the AC power source AC100V is cut off, the power supply switching circuit 5 is activated and connects the constantly charged capacitor 6 to the oscillation circuit 7 side.
oscillates when supplied with the charging voltage of the capacitor 6, and drives the piezoelectric buzzer 4 with an oscillation output of frequency 2 to warn that the AC power supply has stopped for a certain period of time until the capacitor 6 finishes discharging.

FIG. 3 is a circuit diagram showing a specific embodiment of the present invention.

First, to explain the configuration, a commercial AC 100V AC power source is stepped down by a power transformer 8, then rectified by a diode bridge 9, and then a constant DC power source voltage is obtained by a constant voltage circuit 10. A relay 11 energized by DC voltage supply is provided on the output side of the constant voltage circuit 10, and a capacitor C1 is further connected via a resistor R1 and a diode D1. The positive side of the capacitor C1 is connected via the normally closed contact 12 of the relay 11 to the drive circuit section of the piezoelectric buzzer 14, which is made up of an oscillation circuit 13 and a transistor 15.

Note that the gas detection circuit and its oscillation circuit are omitted.

Next, the operation will be explained.

In a normal state where commercial AC 100V AC power is supplied, the power supply to the drive circuit of the piezoelectric buzzer 14 is cut off when the normally closed contact 12 is opened by energizing the relay 11, and the resistor R1 and Capacitor C1 is always charged to the DC power supply voltage via diode D1.

If the AC power supply AC100V is stopped in this state, the output voltage of the constant voltage circuit 10 becomes zero volts, the relay 11 is restored, and its normally closed contact 12 is closed. Then, the charging voltage of the capacitor C1 is applied to the oscillation circuit 13 and the piezoelectric buzzer 14 via the normally closed contact 12, and the transistor 15 is intermittently turned on and off by the oscillation output of the oscillation circuit 13, causing the piezoelectric buzzer 14 to ring. do. In this case, piezoelectric buzzer 1
Since 4 is an intermittent sound caused by the oscillation circuit 13, the discharge current from the capacitor C1 is suppressed to a sufficiently low level, and the piezoelectric buzzer 14 continues sounding for a sufficient period of time for the user to notice that the power has been cut off.

FIG. 4 is a circuit diagram showing another embodiment of the present invention, and this embodiment is characterized in that switching when the power supply is stopped is performed by operating a transistor instead of a relay.

That is, a PNP type transistor 16 is connected in series with the oscillation circuit 13, and a resistor R is connected to the base of the transistor 16 on the output side of the constant voltage circuit 10.
A divided voltage of 2 and R3 is applied to keep it cut off during normal times.

Therefore, when the AC power supply AC100V stops, the base potential of the transistor 16 becomes zero volts,
The transistor 16 is turned on by the application of the charging voltage of the capacitor C1, and the oscillation circuit 13 is operated to cause the piezoelectric buzzer 14 to intermittently sound by turning on and off the transistor 15.

FIG. 5 is a circuit diagram showing another embodiment of the present invention. This embodiment is characterized in that in addition to the alarm output when the power supply is stopped, the operation of the gas detection circuit can also be confirmed.

First, to explain the configuration, on the output side of the constant voltage circuit 10, a capacitor C2 is charged with a power supply voltage to check the operation of the gas detection circuit when the power is stopped.
is connected via a resistor R6, and a diode D3 is connected in parallel to the resistor R6 to set the discharge direction of the capacitor C2. The gas sensor 18 uses, for example, an element whose electrical resistance decreases when a specific gas flows in, and the divided voltage of resistors R7 and R8 connected in series with the gas sensor 18 is input to the comparator 19 as a detection voltage, and the Zener diode is connected to the comparator 19. ZD
When the voltage exceeds a reference voltage determined by , the output of the comparator 19 is set to H level.

A diode D4 is connected in parallel with this gas sensor 18.
Through transistor 17 (PNP transistor)
A voltage divided by a diode D2 and a resistor R5 is applied to the base of the transistor 17, and the transistor 17 is biased to a cut-off state when the power supply is normal.

The output of the comparator 19 has an AND gate 20
is provided, and the piezoelectric buzzer 13 is driven by turning on and off the transistor 15 based on the output of the AND gate 20.

On the other hand, as a circuit section for issuing an alarm when the AC power source is stopped, substantially the same circuit as shown in the embodiment of FIG. 4 is provided.

Further, the output of the oscillation circuit 14 is applied to one side of the AND gate 20 via the inverter 21, and therefore, under the normal operation of the gas detection circuit section where the output of the comparator 19 becomes H level, an alarm for power outage is issued. is output.

Next, the operation will be explained.

During normal operation when an AC power supply of 100 VAC is applied, each of the transistors 16 and 17 is off, and the capacitors C1 and C2 are charged with the DC power supply voltage by the constant voltage circuit 10.

In this state, if the AC power supply AC100V is stopped, the base voltage of the transistor 17 becomes zero volts and turns on, and the charging voltage of the capacitor C2 is applied to the resistors R7 and R8 via the diodes D3 and D4 and the transistor 17. Since this divided voltage exceeds the reference voltage of Zener diode ZD,
The output of the comparator 19 becomes H level.

At the same time, the base voltage of the transistor 16 also becomes zero volts and turns on, and the charging voltage of the capacitor C1 is applied to the oscillation circuit 14 via the transistor 16, producing an oscillation output. The oscillation output of the oscillation circuit 14 is inverted by the inverter 21 and input to the AND gate 20. At this time, the AND gate 20 is in the permissible state with the H level output of the comparator 19, so the transistor 15 is turned on and off, and the capacitor C2 is turned on and off. Piezoelectric buzzer 1 receives charging voltage supply
3 rings.

By the way, if the gas detection circuit section including resistors R7, R8, R9, Zener diode ZD, and comparator 19 is out of order, the output of comparator 19 will not go to H level even if the AC power supply is stopped, so the AND gate 20 is placed in a prohibited state, and the piezoelectric buzzer 13 does not sound.

Therefore, the operation of the gas detection device can be simply and easily checked by unplugging it from the outlet and checking whether an alarm is issued or not.

As explained above, according to the present invention, a capacitor that is constantly charged by the supply of AC power is switched to the alarm device side when the power supply is stopped, and the charging voltage of this capacitor energizes the alarm device to generate an alarm. As a result, it is now possible to warn that the equipment has stopped functioning in the event of an unplugged outlet, disconnection of the power supply wiring, or power outage, thereby minimizing the occurrence of unmonitorable conditions due to interruptions in AC power. This makes it possible to significantly improve reliability.

In addition, by combining the power outage alarm with the gas detection circuit's operation check function, it is possible to automatically check the operation when the power goes out. Since it can be immediately determined whether the operation of the circuit section is normal or not, an effect that inspection work can be performed simply and easily can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional device, Fig. 2 is a block diagram showing the basic configuration of the present invention, Fig. 3 is a circuit diagram showing an embodiment of the present invention, and Fig. 4 is a block diagram of another device of the present invention. A circuit diagram showing an embodiment. FIG. 5 is a circuit diagram showing another embodiment of the present invention in which means for confirming the operation of the gas detection circuit section is provided. 1...Power supply circuit, 2...Gas detection circuit, 3,
7, 14... Oscillation circuit, 4, 13... Piezoelectric buzzer, 5... Power switching circuit, 6... Capacitor, 8
...Power transformer, 9...Diode bridge,
10... Constant voltage circuit, 11... Relay, 12...
Normally closed contact, 15, 16, 17...transistor,
18... Gas sensor, 19... Comparator, 2
0...AND gate, 21...Inverter, R1
~R10...Resistor, C1, C2...Capacitor,
D1 to D7...Diode, ZD...Zena diode.

Claims (1)

[Scope of Claim for Utility Model Registration] In a gas detection alarm device that is placed in a gas detectable state by supplying an AC power supply and that activates an alarm and issues an alarm when a specific gas is detected, A gas detection alarm device comprising: a capacitor that is constantly charged by supply; and a power supply switching circuit that connects the capacitor to an alarm and energizes the alarm when the AC power source is stopped.