JPS6222413B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas detection device, in which an ultrafine particle resistor having a large dependence on gas is used as a detection element of a gas detection circuit and a resistance element having the same temperature dependence as the detection element. By using
It is an object of the present invention to provide a gas detection device that does not require correction of variations in resistance values of detection elements, can detect with a simple configuration, and is easy to manufacture.

As shown in FIG. 1, the resistance value R of a film resistor composed of ultrafine particles is large with respect to temperature T.
Although it has a complicated dependence, the dependence on temperature T as shown in the figure does not change even if the resistance value R differs.

As in the past, if the ultrafine particle resistor 1 is connected to the power supply 3 in series with the resistor 2 as shown in FIG. In order to obtain the same output voltage, it is necessary to adjust the resistance value of the resistor 2 according to variations in the resistance value of the ultrafine particle resistor 1 and changes in resistance due to temperature. Therefore, when attempting to manufacture a gas detection device using ultrafine particle resistors, this resistance adjustment process becomes a major obstacle.

The present invention realizes a gas detection device that can solve the above problems.

Hereinafter, embodiments of the present invention will be described in detail using FIG.

In FIG. 3, 11 is an ultrafine particle resistor (gas detection element) that is sensitive to gas, and 12 is an ultrafine particle resistor (compensation element) whose surface is coated with a substance that has a gas shielding effect, such as a glass substance. can be,
It is connected in series to the power supply 13. In addition, in FIG. 3A, the output voltage V _p from between the terminals of the compensation element 12 is
Further, FIG. 1B shows a case where the output voltage V _p is obtained from between the terminals of the gas sensing element 11.

Here, the resistance values of elements 11 and 12 are respectively R _x
1 and R _x2 and detecting the gas concentration based on the circuit configuration shown in FIG. 3A will be described. When the resistance value R _x1 of the gas sensitive element 11 changes with the gas concentration, the current in the circuit changes and the voltage V _p across the terminals of the compensating element 12 changes. Therefore, if the correlation between the gas concentration and the voltage V _p is determined in advance, the gas concentration can be detected based on the change in the voltage. The voltage V _p between the terminals of the compensation element 12 is It is expressed as

Therefore, if the value of R _x1 /R _x2 is constant,
The voltage V _p can be kept constant regardless of the absolute values of R _x1 and R _x2 .

Now, as shown in Fig. 1, the ultrafine particle resistor used in the gas detection device of the present invention has an R relative to temperature even if the absolute values are different like that of sample A and sample B.
Since the dependence of R x1 /R x2 is the same, the resistance value ratio R _x1 /R _x2 can be kept constant regardless of the operating temperature.

In addition, an element 1 composed of an ultrafine particle resistor
By manufacturing 1 and 12 at the same time, there is almost no variation in the resistance value ratio R _x1 /R _x2 between samples. It is no longer necessary to adjust the value of .

Furthermore, another feature of the ultrafine particle resistor is the resistance value R in an atmosphere where there is no gas to be measured.
The point is that the ratio between _p and the resistance value R _G in the atmosphere where the gas to be measured exists is constant regardless of the value of R _p as shown in FIG.

That is, it can be expressed as R _G /R _p =K (constant) (3). For example, R _p =
Assuming that the value of R _x1 changes to the value of R _G due to gas, the detected output voltage V _p in _Fig . 3 is calculated from equations (1) and (2). becomes. However, as a matter of course, it is necessary that R _x2 be shielded from the gas atmosphere.

In other words, the feature of the ultrafine particle resistor is that even if the absolute values of R _x1 and R _x2 vary, the ratio R _x1 /R _x2 is constant regardless of the operating temperature, and R _G /R _p By taking advantage of the feature that V remains constant regardless of the value of _Rp , and by simultaneously fabricating it, the detected output voltage V
_p can always be kept constant.

FIGS. 5A and 5B show the circuit configuration of still another embodiment. This is a combination of elements 11 and 12 and a field effect transistor (FET) 14, and is capable of operating an alarm device such as a buzzer or a display device such as a lamp. here
A relay 15 is used as a load for the FET 14 to control on/off of an alarm device and a display device.

The gate bias voltage of the FET 14 changes depending on the gas concentration. As mentioned above, elements 11,1
Since the voltage divided by 2 is substantially constant regardless of temperature changes, the reliability of operation of the device is extremely high. And as FET14, for example
By using MOSFETs and utilizing their threshold characteristics, current can be supplied to the load only when the gas concentration is above a certain level, resulting in a power-saving device. Therefore, this is advantageous for devices that use batteries as a power source. Of course,
If there are no particular restrictions on the power supply, and if the gas concentration is to be quantitatively detected, transistors and circuit configurations with appropriate characteristics may be selected. In this example, the sensing element and the compensation element were used as independent elements each having a pair of electrodes, but it is easy to form both elements on the same substrate, for example, in which case one electrode of each element is Since they can be shared, only three electrodes are required, and the effect is exactly the same in this case.

As is clear from the above description, according to the present invention, by using an ultrafine particle resistor as a gas detection element and a compensation element, it is possible to realize a gas detection device with a simple configuration, accuracy, and easy manufacture. can.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the temperature dependence of the resistance value R of the ultrafine particle resistor used in the gas detection device of the present invention, and FIGS. 2A and 2B are diagrams showing the configuration of a conventional gas detection device, respectively. 3A and 3B are diagrams showing the configuration of an embodiment of the gas detection device of the present invention, respectively, and FIG. 4 shows the resistance value R _p of the ultrafine particle resistor in air and the resistance value R _G in a gas atmosphere. FIGS. 5A and 5B are diagrams showing configurations of other embodiments, respectively. 11...Gas detection element, 12...Compensation element, 1
3...Power supply.

Claims (1)

[Claims] 1 An element formed by forming an ultrafine particle resistor on an insulating support base having a pair of electrodes consisting of first and second electrodes, and an insulating support having a pair of electrodes consisting of third and fourth electrodes. An element formed by forming an ultrafine particle resistor having the same temperature dependence as the ultrafine particle resistor on a substrate is connected in series, and one of the elements is used as a gas detection element and the other as a compensation element. A gas detection device characterized by obtaining an output voltage from between electrodes.