JPS6148756A - Gas detecting device - Google Patents

Abstract

PURPOSE:To detect sudden spouting of gas speedily and to perform gas detection in which human life is hardly exposed to danger by providing detection timing points in one cycle. CONSTITUTION:A detecting element 4 to which a couple of heater electrodes 3 and 3 are fixed in one body with a oxide semiconductor is provided. Power sources 1 and 2 heat the couple of heater electrodes 3. A power source 5 detects the resistance between the couple of heater electrodes 3. A timing circuit 7 controls a detection sampling circuit 8 through the power sources 1 and 2 and a pulse frequency multiplying circuit 9. The pulse frequency multiplying circuit 9 allows detection plural times in every cycle T, so speedy response is obtained. A sampling circuit 8 outputs a string of V1, V2...Vn corresponding to detection timing points t1, t2...tn and the string varies with gas concentration. This is outputted as an alarm output sequentially to perform high-precision, speedy detection.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a gas detection device that enables high-speed response by providing detection timing multiple times between one cycle of high temperature and low temperature.

[Prior art]

There is a conventional gas detection device called MQhM shown in FIG. 1, which operates at the timing shown in FIG.

In FIG. 1, 3 is a pair of heater electrodes, 4 is a gas detection element in which the heater electrode 3 is integrally solidified with an oxide semiconductor, and 1 and 2 are power supplies, respectively, for the pair of heaters. Heats 3ft of dual-purpose electrode. Reference numeral 5 denotes a power source for detecting the resistance between the pair of heater electrodes 30, 6 a detection resistor, and 7 the power sources 1, 2, and a detection sampling circuit. Timing to roll each 8? Each.

Power source 1 and power source 2 are activated at the timing shown in FIG.

That is, the high temperature is maintained at high temperature T1 and the low temperature is maintained at low temperature T2 by controlling the power applied to the pair of heater electrodes 3. At high temperature T1, degassing of the adsorbed gas is promoted because the temperature is maintained at high temperature, and at low temperature T2, adsorption of the four gases is promoted by keeping the temperature at low temperature. At this low temperature T
2, gas is detected by the detection sampling circuit 8 only at the detection timing t0. Normally, this detection timing t. is set immediately before the start of high temperature T. Further, the high temperature time T and the low temperature time T2 are repeated as one cycle. One cycle usually lasts from several tens of seconds to several minutes.

Because the conventional device is configured in this way, the cycle takes several tens of seconds to several minutes, making quick detection impossible. Also, the detection timing is 1 within 1 cycle.
Since there is only one cycle and the detection is not performed until the next cycle, there is a drawback that a sudden eruption of gas cannot be detected and there is a possibility of endangering human life.

[Summary of the invention]

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and by setting detection timing multiple times during one cycle, sudden gas ejections can be quickly detected and human lives can be saved. This invention provides a gas detection device that does not put the gas in danger.Hereinafter, this invention will be explained with reference to the drawings. [Embodiments of the Invention] FIG.
The figure is a timing waveform diagram for explaining the operation. In the embodiment 13'll of FIG. 3, 1 to 8 are the same as those in FIG. 3, and 9 is a pulse frequency multiplier circuit.

Next, the operation of the embodiment shown in FIG. 3 will be explained using FIG. 4.

In FIG. 4, 1. ．． 1. ．． 1.・・・・・・to
is the detection timing. This detection timing t.

t2. . . . tll is provided a plurality of times, ie, n times, during the cycle T by providing a pulse frequency count doubler circuit 9 as shown in FIG. 3, thereby enabling a quick response. With this configuration, the detection timing J+t2,...
. . . Output string V1, 72 of the detection sampling circuit 8 according to t, + . . . v, (not shown)
is output. The output series VB and V2°Vyu change in accordance with the gas concentration. By sequentially outputting this as an alarm output, highly accurate and quick detection can be achieved.

In addition, output column V1. Vz, . . . vll vary depending on the type of gas. This is because the reaction times for degassing and gas adsorption are different. By utilizing this, one gas detection element 4 can be used as a variety of gas detection elements.

In the above embodiment, the pulse frequency multiplier circuit 9 is installed multiple times during the detection timing ttl cycle, or alternatively, the sampling period of the detection sampling circuit 8 itself may be accelerated.

〔Effect of the invention〕

As explained above, the present invention includes a gas detection element in which a pair of isolated heater electrodes are integrally made of an oxide semiconductor, a detection sampling circuit, and a period T when the pair of heater electrodes are connected at a high temperature. , a timing circuit for repeating the cycle of T2 at low temperature, and one of the cycle of T1 at high temperature and T2 at low temperature.
Since multiple detection timings for gas detection are provided during the cycle, there is an advantage that a highly accurate gas detection device can be obtained.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a conventional gas detection device, FIG. 2 is a timing waveform diagram of the circuit in FIG. 1, FIG. 3 is a graphic diagram showing an embodiment of the present invention, and FIG. FIG. 3 is a timing waveform diagram of the embodiment shown in FIG. In the figure, 1.2 is a power supply, 3 is a heater electrode, 4 is a gas detection element, 5 is a power supply, 6 is a detection resistor, T is a timing circuit, 8 is a detection sampling circuit, and 9 is a pulse frequency multiplication circuit. . Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent: Masuo Oiwa (2 others) Figure 1 °/ Figure 2 Figure 3 Figure 4) --T→

Claims (1)

[Claims] A gas detection element made of a pair of isolated heater electrodes integrated with an oxide semiconductor, a detection sampling circuit,
In the gas detection device having a timing circuit that causes the pair of heater electrodes to repeat a cycle of high temperature T_1 and a cycle of low temperature T_2, during one cycle of the high temperature T_1 cycle and the low temperature T_2 cycle. A gas detection device characterized in that the detection sampling circuit has a plurality of detection timings for gas detection.