JPS6210871Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a gas leak alarm device. Conventional gas leak alarm devices issue an alarm when the gas concentration is a fraction of the explosive limit in order to prevent explosion accidents, but because they can only detect one concentration level, they are not practical. was low. In other words, in the kitchen of a typical home, ventilation often becomes necessary before the explosion limit is reached, and the concentration of miscellaneous gases such as alcohol vapor is often the same as that of the gas to be captured. It was difficult to set it up by just doing so.

Therefore, the purpose of this invention is to provide a gas leak alarm device that can improve its practicality.

An embodiment of this invention is shown in FIG. That is, this gas leak alarm device includes an operational amplifier (comparator) OP 1 that generates an output when the gas detection signal voltage V _IN exceeds the level V ₁ , and an operational amplifier (comparator) OP ₁ that generates an output when the gas detection signal voltage V _IN exceeds the level V ₁ . an operational amplifier (comparator) OP ₂ that generates an output when the level V ₂ is exceeded;
Operational amplifier _OP3 starts oscillation operation in response to the output of operational amplifier _OP1 , and light emission lights up continuously (when not oscillating) and blinks in response to the oscillation cycle when operational amplifier (oscillator) _OP3 oscillates. It is equipped with a diode (indicator) LED and a buzzer (alarm) Bz that responds to the output of the operational amplifier OP ₂ and sounds intermittently in accordance with the oscillation cycle of the operational amplifier OP ₃ .

Next, the configuration and operation of this gas leak alarm device will be explained in more detail. That is, in this gas leak alarm device, a gas detection signal voltage V _IN from a gas sensor or the like is applied between input terminals T ₁ and T ₂ . This input terminal T ₁ is connected to operational amplifiers OP 1 and OP ₂ whose inverting input ends are connected to each connection point of a series circuit of resistors R ₁ to _{R 3 connected} to a power supply terminal T ₃ .
The terminal _T2 is connected to the resistor _R1 side of the series circuit of resistors _R1 to _R3 . On the other hand, the output terminal of the operational amplifier OP ₁ is connected to the inverting input terminal of the operational amplifier OP ₃ via the backflow blocking diode D ₁ , and the output terminal of the operational amplifier OP 2 is connected to the inverting input terminal of the operational amplifier OP ₃ .
It is connected to the output terminal of operational amplifier OP ₃ via Bz and backflow blocking diode D ₂ . This operational amplifier OP ₃ has its non-inverting input terminal connected to the connection point of a series circuit of resistors R ₄ and R ₅ (connected to power supply terminal T ₃ ), and also has a capacitor C for determining the oscillation period and a resistor R. ₆ and a positive feedback resistor to stabilize oscillation.
R ₇ are connected relationally. A series circuit of a light emitting diode LED and a current limiting resistor _R5 is connected to the output terminal of the operational amplifier _OP3 . In this case, operational amplifiers OP ₁ to _{OP 3} compare the voltages applied to their inverting and non-inverting inputs, respectively, and when the voltage applied to their inverting input is greater, the output is at a low level (0 volts). The output becomes high level (Vcc) when the voltage applied to the non-inverting input is greater.

Next, the operation of this gas leak alarm system will be explained assuming that the gas detection signal voltage V _IN shown in FIG. 2 is added.

Gas detection signal voltage V _IN is level V ₁ (=R ₁ ×
Vcc/(R ₁ + R ₂ + R ₃ )) (at all times), the output terminals of operational amplifiers OP ₁ and OP ₂ are both at low level, and the charge in capacitor C is discharged through backflow blocking diode D ₁ . , the output of operational amplifier OP ₃ is at a high level and the light emitting diode LED is lit. The gas detection signal voltage V _IN is at level V ₁ during time T ₁ after time t ₁ and during time T ₂ after time t ₂ .
, the output of operational amplifier OP ₁ is inverted and becomes a high level, and the charging and discharging through resistor R ₆ of capacitor C ₁ is repeated, causing operational amplifier OP ₃ to oscillate, which causes the light emitting diode LED to blink. do. In this case, the gas detection signal voltage V _IN is at the level
V ₂ or less, the output of operational amplifier OP ₂ maintains a low level state, and the backflow blocking diode
Since no current flows from operational amplifier OP ₃ to operational amplifier OP ₂ due to D ₂ , buzzer Bz does not sound. Also, after time _t3 , the gas detection signal voltage V _IN
When exceeds the level V ₂ , the output of the operational amplifier OP ₂ is also inverted and becomes a high level, and power is supplied to the buzzer Bz, which sounds intermittently depending on the output state of the operational amplifier OP ₃ .

In this way, the gas leak alarm device of this embodiment blinks the light emitting diode LED when the gas detection signal voltage V _IN exceeds the level _V1 , and the level
Since the buzzer Bz is set to sound when the level _V2 , which is higher than _V1 ,
_IN can be notified in two stages (for example, a caution signal and a warning signal), which can prompt ventilation at the initial stage of a gas leak or ventilation of miscellaneous gases. It can be easily changed independently by changing the resistance value, and the detection level setting can be changed extremely easily depending on the installation location. Also, light emitting diode LED
Since it is made to light up all the time, it can also have a power supply display function, and there is no need to provide a separate power supply display circuit. Furthermore, since the circuit is configured with a minimum number of logic elements, the cost is low and failures are low.

As mentioned above, the gas leak alarm of this invention is
a first comparator that produces an output when the gas detection signal voltage exceeds a first level; and a first comparator that produces an output when the gas detection signal voltage exceeds a second level that is higher than the first level. a second comparator for
an oscillator that starts oscillating in response to the output of the first comparator; an indicator connected to the output terminal of the oscillator that lights up continuously when the oscillator is not oscillating and flashes in response to the oscillation operation; A backflow blocking diode is connected in series between the output terminal of the second comparator and the output terminal of the oscillator, and when the output of the second comparator is generated, intermittent ringing occurs in response to the oscillation operation of the oscillator. Since it is equipped with an alarm,
The gas detection signal voltage can be notified in two stages, allowing ventilation at the initial stage of a gas leak or ventilation of miscellaneous gases. Moreover, the detection level of gas concentration can be easily set independently by changing the resistance value. Moreover, it is extremely easy to change the detection level setting depending on the installation location. In addition, a single oscillator can cause indicators and alarms that operate at different signal levels to blink and sound intermittently, and by lighting the indicator continuously when the oscillator is not oscillating, the indicator can have a power indication function. It can be made to stand,
The circuit configuration is simple and costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a gas leak alarm device according to an embodiment of this invention, and FIG. 2 is a waveform diagram for explaining its operation. OP ₁ , OP ₂ , OP ₃ ... operational amplifier, LED ... light emitting diode, Bz ... buzzer, D ₂ ... backflow blocking diode.

Claims (1)

[Scope of utility model registration request] a first comparator that produces an output when the gas detection signal voltage exceeds a first level; and a first comparator that produces an output when the gas detection signal voltage exceeds a second level that is higher than the first level. a second comparator that starts oscillation in response to the output of the first comparator; A backflow blocking diode is connected in series between an indicator that blinks, an output terminal of the second comparator, and an output terminal of the oscillator.
and an alarm that sounds intermittently in response to the oscillation operation of the oscillator when the output of the comparator is generated.