JPS589375B2 - gas noise - Google Patents

Description

[Detailed Description of the Invention] The present invention generates an alarm when an abnormal concentration of gas is generated, and also prevents the voltmeter pointer from swinging out of the way when an abnormal concentration of gas occurs, preventing a malfunction from occurring. The purpose is to

Recently, household gas alarms based on metal oxide semiconductors such as ZnO and Sn02 have been used, but these are only used to detect air pollution because the concentration cannot be determined unless the gas concentration exceeds a specified value. It was not suitable for.

Therefore, it would be even more convenient to install a voltmeter so that the gas concentration can be visually checked, and use it not only to detect abnormal gas leaks but also to check the timing of ventilation.

However, in general, the air pollution in a house is only a few tens of ppm in terms of reducing gases detected by gas-sensitive semiconductors.

For example, when grilling fish, the concentration of reducing gas near the ceiling is about 30 to 60 ppm, and in urban areas where automobile exhaust gas is present, it is about several ppm to several + ppm.

Therefore, the voltmeter must display an extremely low gas concentration, one hundredth of the several thousand ppm, which is the alarm limit for general alarms.

However, things are not always in such a dilapidated state in private residences.

In addition to gas leaks that cause accidents, gas leaks of several thousand to tens of thousands of ppm occur when igniting or extinguishing gas appliances, and cigarette smoke contains gas components of several thousand ppm. There are things to do.

In this way, when trying to display air pollution in a general home using a voltmeter, we take into account the possibility of gas leakage, so even in the case of an abnormal concentration, the voltmeter pointer will swing out and the voltmeter will malfunction. There was a problem that required special consideration.

The present invention eliminates the drawbacks of the prior art.

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

1 is a power supply, 2 is a heater transformer made of a gas-sensitive semiconductor 3, 4 is an overcurrent prevention resistor, 5 is a voltmeter, 6 is a resistor for applying voltage to the voltmeter 5, and 7 is a voltage applied to the voltmeter 5. bidirectional zener diode, which limits
8 is a stabilizing resistance of the thyristor 9; 10 is the thyristor 9;
It is an alarm device connected to.

With the above structure, when a reducing gas such as carbon monoxide comes into contact with the gas-sensitive semiconductor 2, the resistance value R of the gas-sensitive semiconductor 3 decreases, and the voltage across the resistor 6 increases, causing the voltmeter to rise. The voltage applied to the voltmeter 5 increases, the pointer of the voltmeter 5 swings, and the concentration of the gas is displayed.

Next, when the concentration of the gas component becomes even higher and the value of the voltage across the resistor 6 rises to the Zener voltage of the Zener diode 7, a bypass circuit to the Zener diode 7 is formed, and the voltage applied to the voltmeter 5 is limited, and the voltage The deflection of the pointer of the meter 5 is also limited.

Furthermore, when the value obtained by multiplying the zener current i by the resistance value r of the stabilizing resistor 8 exceeds the trigger voltage of the thyristor 9, the thyristor 9
is triggered and the alarm device 10 starts to issue an alarm.

FIG. 2 is a time chart showing the voltage measured by the voltmeter 5 and the alarm time of the alarm 10, with time plotted on the horizontal axis.

Reference numeral 11 represents the Zener voltage of the Zener diode 1, 12 represents a curve representing the temporal change in air contamination using measured voltage, and 13 represents the time during which the alarm device 10 performs an alarm operation.

Reference numeral 14 indicates a voltage portion where the voltage applied to the voltmeter 5 is cut by the Zener diode 7.

Air pollution increases from time t1 to time t2 and from time t3 to time t
Between 4 and 4, Zener diode 7 is connected to voltmeter 5.
operates, the voltage applied to the voltmeter 5 is limited, and the pointer of the voltmeter 5 shows the highest value.

In the alarm device 10, the thyristor 7 is triggered to generate an alarm.

The gas concentration display device of the present invention is provided with a voltmeter that displays the resistance change of a gas-sensitive semiconductor mainly composed of metal oxide semiconductors such as ZnO and SnO2 as a voltage, and is inserted into an applied voltage limiting circuit of the voltmeter. This device is characterized by the fact that a voltage limiting element (Zener diode) is used as the trigger element for the output circuit of a thyristor installed for alarm purposes, so even if an abnormal concentration of gas is generated, the voltmeter will not be able to swing out and there is a risk of malfunction. It has an excellent effect of activating the alarm and generating an alarm by using the voltage that is limited to a certain voltage and that there is no voltage.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram of a gas concentration display device according to an embodiment of the present invention, and FIG. 2 is a time chart showing the display of a voltmeter and the operation of an alarm. 1...Power supply, 2...Transformer, 3...
...Gas sensitive semiconductor, 5 ... Voltmeter, 6 ... Resistor, 1 ... Zener diode, 8 ... Stable resistor, 9. ...Thyristor, 10...Alarm.

Claims (1)

[Claims] 1. A voltmeter is provided to display the resistance change of a gas-sensitive semiconductor mainly composed of metal oxide semiconductors such as ZnO and Sn02 as a voltage, and a voltage limiting element (Zena diode) inserted into the applied voltage limiting circuit of the voltmeter is installed. A gas concentration display device characterized in that it is commonly used as a trigger element of an output circuit of a thyristor provided for alarm.