KR880003147Y1 - An alarm - Google Patents

Abstract

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Description

Malfunction prevention circuit of gas sensor

1 is an overall circuit diagram of a general gas alarm circuit.

2 is a circuit diagram of a malfunction prevention circuit of the present invention.

FIG. 3 is a voltage waveform diagram of respective parts of FIG.

* Explanation of symbols for main parts of the drawings

6 delay unit 7 initial malfunction prevention unit

8: setting part 9: driving part

TM ₂ , TM ₃ : Timer R _23- R ₃₄ : Resistance

C ₈ -C ₁₁ : condenser D ₃ -D ₆ : diode

ZD ₃ : Zener Diodes Q ₆ , Q ₇ , Q ₉ : Transistor

Q ₈ : Darlington Transistor RL ₂ : Relay

SN: Gas Sensor

The present invention relates to a malfunction prevention circuit of a gas sensor for preventing a malfunction of a gas alarm that warns of a gas leak.

Conventional gas alarm detects when gas leaks and sounds an alarm, and at the same time, it operates a fan to ventilate the surrounding air. Since the gas components are not easily discharged, the gas concentration inside and outside the gas sensor is different so that the gas alarm is often operated even when the surrounding gas concentration does not reach a certain limit.

The present invention is to solve the conventional closed end as described above, by supplying an overvoltage or higher than the rated voltage to the gas sensor once at a suitable time interval to heat this gas sensor to vent the gas remaining in the gas sensor inside the sensor B. It is designed to prevent the malfunction of the gas alarm by keeping the external gas concentration in the same state.

2 is a circuit diagram of the present invention, in which a delay unit 6 is composed of a time delay timer TM ₂ , a pulse period setting capacitor C ₇ , a resistor R ₂₃ (R ₂₄ ), and a capacitor C ₈ . The output terminal Q of the timer TM ₂ in the delay unit 6 is connected to a diode D ₃ (D ₅ ), a resistor (R _25- R ₂₈ ), a transistor (Q ₆ ), and a capacitor (C ₉ ). Diode (D ₄ ) (D ₆ ), resistors (R ₂₆ -R ₃₃ ), transistors (Q ₇ ), capacitors (C ₁₀ ) (C ₁₁ ), and a timer (TM ₃₎ and gongjeop the setting unit (8), the timer (TM ₃₎ the output Darlington transistor to (Q) (Q _8), a timer (TM ₃₎ in said a setting unit (8), The driver ( ₉ ) is provided with a relay (RL ₂ ) relay driving transistor (Q ₉ ), a resistor (R ₃₄ ), and a zener diode (ZD ₃ ) for supplying a Vcc voltage higher than the rated voltage to the gas sensor (SN) during the high 'level output period. ), Where V _DD is a DC power supply terminal. Now, P ₁ -P ₄ , RS, S, and TG are programmable terminals, reset terminals, set terminals, and trigger terminals of a timer (TM ₂ ) (TM ₃ ), respectively, and a, b, and c are relays (RL ₂ ). Each contact is.

The operation and effects of the present invention as the configuration is as follows.

First, the circuit operation state of the general gas alarm system will be described with reference to FIG.

The gas sensor SN in the gas detector 1 detects the leaked gas, that is, the resistance value decreases as the detected gas concentration increases, and the resistance value of the sensor SN corresponds to the OP amplifier OP _1. The output of this OP amplifier OP ₁ is generated by increasing the voltage difference of the positive terminal of < RTI ID = 0.0 > The output of the OP amp output comparator (OP ₂₎ back in (OP ₁₎ is compared with a reference voltage that is maintained at a constant voltage by a Zener diode (ZD ₁₎ by re-comparator (OP _2), the comparison value again resisted It is represented by the output of the comparator OP ₂ by the partial pressure value of (R ₃ ) (R ₄ ). At this time, the voltage value adjusted by the resistor R ₃ and R ₄ is set by the following equation.

Where Vout is the output voltage of comparator (OP ₂ ) and V ₂ is the rated voltage of zener diode (ZD ₁ ).

The 'High' level, the output of such comparator (OP ₂₎ is the time at the same time as the NAND gate is naenteu by (ND ₁₎ and its output is lit, the LED (L ₁₎ for a gas leakage represented by this so reversed to 'low' level, As the delay part 2 time delay timer TM ₁ is triggered, the timer TM ₁ performs a count function based on the period set by the resistor R ₇ and the capacitor C ₃ . After the delay time, the 'high' level is output to the output terminal Q.

The 'high' level output again turns on the Darlington transistor Q _{1 in the} fan driver 3 to drive the relay RL ₁ to operate the ventilation fan FM and generate an alarm. The transistor Q ₂ in the section 4 is 'turned on' to create a condition under which the display LED L ₃ and the buzzer BZ operate, using a time delay timer TM ₁ . The reason is to prevent the gas alarm from malfunctioning as if a lot of gas leaks at the moment, as if there is a certain level of gas in the entire outside air.

On the other hand, in order for the LED L ₃ and the buzzer BZ in the aforementioned alarm generating unit 4 to operate, the output of the timer TM ₁ becomes the 'high' level and the OP amplifier by the gas sensor SN ( The output of OP ₃ ) must also be at the 'high' level. In this case, the output of the NAND gate ND ₂ is at the 'low' level, and the inverter (N ₁ ) (N ₂ ) and the resistor (R ₁₀ ) (R ₁₁ ) and the transistors Q ₂ -Q ₄ are controlled by a multivibrator composed of a capacitor C ₄ and the LED L ₃ and the buzzer BZ operate. At the same time, the output of the OP amplifier OP ₄ in the display unit 5 is also at the 'high' level, and each LED is turned on by a multivibrator including an inverter N ₄ , N ₅ , and a capacitor C ₆ . (L ₄ ) and (L ₅ ) are turned on alternately, that is, when a gas leak is detected, each LED (L ₄ ) (L ₅ ) in the display unit 5 blinks, and the leaked gas has a sufficient saturation level. When the alarm buzzer (BZ) in the alarm (4) is to sound.

According to the circuit of the present invention of FIG. 2, as the gas sensor SN in the gas alarm repeats the process of detecting a gas leak, the gas component is not discharged inside the sensor and remains as it is. The circuit operation state will be described in detail as being configured to solve the problem that the gas alarm operates even when a certain threshold is not reached.

When the power is initially input, the Vcc power is input through the resistor R ₂₈ and the diode D _{3 in} the initial malfunction prevention unit 7 to trigger the timer TM ₃ in the setting unit 8. Therefore, this timer TM ₃ has its output stage Q at the 'high' level for a predetermined time set by the resistor R ₃₁ and the capacitor C ₁₁ , where the output period of the timer TM ₃ is below. Same as the equation.

At the same time, the 'high' level output again turns on the Darlington transistor Q ₈ in the driving unit 9 to drive the relay RL ₂ , whereby the relay contact a causes the contact c. By being connected to the gas sensor SN, a Vcc voltage equal to or higher than the rated voltage is supplied to the gas sensor SN for a predetermined time which is the output period of the timer TM ₃ . As shown in FIG. 3, the rated voltage of the gas sensor SN is set to 1 / 2Vcc, and heat is generated inside the gas sensor SN by the Vcc voltage supply as described above. The air including the gas is ventilated to prevent malfunction of the sensor SN due to the gas remaining therein.

On the other hand, the 'high' level output of the timer TM ₃ is outputted to the output stage Q of the timer TM ₃ again by the internal count function and inverted to the 'low' level when the above-described period T ₁ is completed. As a result, the Darlington transistor Q ₈ in the driver 9 is 'turned off' so that the relay RL ₂ is also 'off', so that the relay contact a is opened and the contact b is contacted c. ) Is supplied to the sensor SN at a voltage of 1/2 Vcc which is a rated voltage.

As described above, when the output of the timer TM ₃ becomes the 'low' level, the reset terminal of the time delay timer TM ₂ in the delay unit 6 becomes the 'low' level through the resistor R ₃₃ . The setting function T ₂ is performed during the setting time. The setting time T ₂ is given by a clock frequency and an internal counter multiple of the timer TM ₂ , and can be expressed by the following equation.

Therefore, after this delay time T ₂ , the output stage Q of the timer TM ₂ is at the 'high' level, and this 'high' level output is again converted to the diode D ₄ and the resistor (D ₄ ) in the setting unit 8. By turning on transistor Q ₇ through R ₂₆ ), the emitter current of transistor Q ₇ triggers timer TM ₃ through diode D ₆ . That is, after the delay time T ₂ of the time delay timer TM _{2 in the} delay unit 6 has elapsed, the output of the timer TM _{3 in the} setting unit 8 again becomes a 'high' level so that the sensor ( Since the residual gas inside the SN) is removed, it is effective to set the delay time T ₂ to approximately one hour and the delay time T ₁ to approximately one minute.

On the other hand, the 'high' level output of the time delay timer TM ₂ in the delay unit 6 described above is only charged after the capacitor C ₉ is charged through the diode D ₃ in the initial malfunction prevention unit 7. a transistor (Q ₆₎ 'turn-on' since it diode (D ₅₎ is let affect the trigger input of the timer (TM ₃₎ in the setting portion 8 according to the forward difference between both ends, wherein the diode (D ₄ -D ₇ ) is configured to prevent reverse current and resistors R ₂₆ and R ₂₇ are configured for the base bias of transistor Q ₆ .

As described above, the present invention can effectively eliminate the malfunctions generated in the conventional gas alarm, which is a useful design for achieving high quality products.

Claims (1)

The delay unit 6 is composed of a time delay timer TM ₂ , a pulse period setting capacitor C ₇ , a resistor R ₂₃ (R ₂₄ ), and a capacitor C ₈ . The output terminal Q of the timer TM ₂ is an initial malfunction prevention unit 7 consisting of a diode D ₃ (D ₅ ), a resistor (R _25- R ₂₈ ), a transistor (Q ₆ ) and a capacitor (C ₉ ). At the same time, a setting unit comprising a diode (D ₄ ) (D ₆ ), a resistor (R ₂₆ -R ₃₃ ), a transistor (Q ₇ ), a capacitor (C ₁₀ ) (C ₁₁ ), and a timer (TM ₃ ) 8) and the output stage Q of the timer TM _{3 in} the setting section 8 is connected to the darlington transistor Q ₈ and the gas sensor during the 'high' level output period of the timer TM ₃ . It is characterized by a configuration connected to a drive unit 9 consisting of a relay (RL ₂ ) relay driving transistor (Q ₉ ), a resistor (R ₃₄ ), and a zener diode (ZD ₃ ) for supplying a Vcc voltage equal to or greater than the rated voltage to SN). Malfunction prevention circuit of the gas sensor.