JPH0619085Y2 - Humidity sensor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a humidity sensor device having a dew condensation preventing function.

(Prior Art) Currently, two types of humidity sensors are mainly used: a ceramic humidity sensor and a polymer humidity sensor.

Since these humidity sensors cannot maintain their initial characteristics due to the dew condensation phenomenon during use, they must be removed when dew condensation occurs or measures must be taken to prevent dew condensation.

Generally, since the dew condensation removing or preventing means is accompanied by heat generation, it is difficult to remove or prevent dew condensation in a polymer humidity sensor whose moisture sensitive element is made of a polymer film. Measures can be taken to remove or prevent condensation.

Conventionally, it is possible to remove or prevent dew condensation in a ceramic humidity sensor, for example, by the technique disclosed in Japanese Patent Publication No. 61-52944.

That is, a coiled heater is arranged around 2 mm around the ceramic humidity sensor to which the lead wire is attached,
Further, this surrounding is covered with a protective member, and in order to incinerate dust, oil and the like adhering to the sensor, the heater is periodically heated to about 450 ° C. and cleaned.

By incinerating dust, oil, and the like, this humidity sensor eliminates the dew condensation state after cleaning, and has an effect that humidity can be detected accurately as such.

However, the humidity sensor with the above configuration is 450 ° C.
Since it has to be heated up to (a), the power consumption must be increased.

(B) Humidity cannot be measured during heating of the coiled heater.

(C) It is dangerous if flammable gas flows in during heating.

(D) A high heat resistant alumina substrate must be used as the mounting substrate.

(E) Since the element body and the coiled heater are brought as close as possible to each other and the structure is complicated, the flow of the gas to be measured to the moisture sensitive portion is not good.

It was a result of dealing with problems such as.

Therefore, it is conceivable to reduce the distance between the element body and the coil-shaped heater to reduce the power consumption as much as possible, but (a) the flow of the gas to be measured becomes worse.

(B) There is a risk of contact between the two.

However, it could not be made extremely small.

(Problems to be solved by the invention) As described above, since the conventional humidity sensor removes the dew condensation by heating at high temperature, there is a difficulty in always measuring the humidity accurately while preventing the dew condensation. I had a task to do.

The present invention has been made in view of the above circumstances, and it is possible to perform continuous measurement without stopping humidity measurement during heating for the purpose of preventing dew condensation while minimizing the power consumption. An object of the present invention is to provide a humidity sensor device that can contribute to cost reduction and cost reduction.

[Configuration of the Invention] (Means for Solving the Problems) A humidity sensor device according to the present invention is a humidity sensor device in which a ceramic humidity sensor and a heating resistor are arranged to face each other on a substrate. The facing distance between the center of the heat generating resistor and the center of the facing surface of the heat generating resistor is 1 (mm), and the power consumption of the heat generating resistor is P
(W) It is characterized in that it is set in a range in which the relationship is established.

(Operation) According to the humidity sensor device having the above configuration, when the facing distance l (mm) is in a range where the above inequality relationship is satisfied, the ceramic humidity sensor compares the surrounding range by heating the heating resistor. Then, the temperature rises by 2 to 4 ° C.

Therefore, even if the relative humidity of the surroundings reaches 100%, the relative humidity stays at 90 to 95% in the immediate vicinity of the ceramic humidity sensor and does not reach the dew condensation state, and the humidity can be measured even during heating. Becomes

The power consumption P (W) of the above inequality is 0.32 to 0.
The reason why the range is set to 8 W is as follows. That is, in order to reduce the power consumption P to less than 0.32 W and obtain the same effect as described above, the facing distance l (mm) must be shortened, but in that case, the humidity sensor and the heating resistor are too close to each other. Therefore, the flow of the gas to be measured may deteriorate, and there is a risk of contact due to vibration and impact, which is not preferable.

Further, in order to increase the power consumption P to more than 0.8 W and obtain the same effect as described above, the facing distance l (mm) must be increased by that much, which is not preferable from the viewpoint of space saving and energy saving. .

(Embodiment) Hereinafter, the present invention will be described with reference to the drawings.

That is, as shown in FIG. 1, a ceramic humidity sensor 3 provided with a moisture sensitive portion 2 on a substrate 1 and a heating resistor 4 made of, for example, a column for preventing dew condensation are arranged to face each other with a gap therebetween. In this case, the facing distance 6 between the center of the moisture sensitive portion 2 of the ceramic humidity sensor 3 and the center of the facing surface 5 of the heating resistor 4 is set to 1 (mm), and the heating resistor 4 is Power consumption of P (W), It is set in a range where the relationship of is established.

Next, the present invention will be described in detail.

In other words, from the results of various studies, the present invention proposes that the power consumption for preventing dew condensation is minimized, and that the humidity can be continuously measured even during heating to prevent dew condensation. The following examples will be described on the assumption that the temperature rise of the ceramic humidity sensor 3 is 2 to 4 ° C. as compared with.

That is, the ceramic humidity sensor 3 shown in FIG. 1 has a size of 10 × 12 × 5 mm, and the heating resistor 4 has a resistance of 270 Ω. The voltage applied to the heating resistor 4 is 11. As a result of examining the temperature rise ΔT of the ceramic humidity sensor in comparison with the ambient temperature when the facing distance 1 was changed under the condition of 6 V and power consumption of 0.5 W, the results are shown in FIG. It was

As is clear from FIG. 2, the facing distance l at which the temperature rise ΔT is 2 to 4 ° C. when the power consumption is 0.5 W is 4.9 to 1
It was 0.5 mm, and in this case, even in the vicinity of the ceramic humidity sensor, even if the ambient relative humidity became 100%, the ceramic humidity sensor did not reach a dew condensation state.

Based on the above results, the power consumption P (W) and the facing distance l (mm) when the power consumption of the heating element is changed in order to raise the temperature of the ceramic humidity sensor by 2 to 4 ° C compared with the ambient temperature The result shown in the table was obtained as a result of obtaining the relationship of (1) from the above inequality.

It is also possible to raise the temperature of the ceramic humidity sensor to 2 to 4 ° C. by making the power consumption of the heating element smaller than 0.32 W or making the power consumption larger than 0.8 W. When the electric power is made smaller than 0.32 W, the facing distance l is too small and the flow of the gas to be measured is bad, and there is a risk that the ceramic humidity sensor and the heating resistor will come into contact with each other due to vibration and shock. .8W
If it is made larger, the facing distance 1 becomes larger, and a wasteful space is required, and at the same time energy saving is taken into consideration, which is not preferable.

According to the humidity sensor device configured as described above, various drawbacks of the humidity sensor having the dew condensation eliminating means having the conventional structure as described above are eliminated, and the structure is not particularly complicated, and the size is reduced. ， Because it is energy-saving, it can meet various demands of users who can continuously measure humidity even when dew condensation is being prevented.
The embedded substrate is not limited to the alumina substrate, and a relatively inexpensive glass epoxy substrate can be used.

[Advantages of the Invention] According to the present invention, a humidity sensor device with high practical value that consumes as little power as possible, can continuously measure humidity even during heating to prevent condensation, and contributes to downsizing and cost reduction Obtainable.

[Brief description of drawings]

1 and 2 show a humidity sensor device according to the present invention. FIG. 1 is a perspective view, FIG. 2 is a front view, and FIG. 3 is a facing distance l-temperature rise ΔT curve diagram of a ceramic humidity sensor. Is. 1 ... Substrate 2 ... Moisture Sensing Part 3 ... Ceramic Humidity Sensor 4 ... Heating Resistor 5 ... Opposing Surface 6 ... Opposing Distance

Claims (1)

[Scope of utility model registration request] 1. In a humidity sensor device in which a ceramic humidity sensor and a heating resistor are arranged on a substrate so as to face each other, the facing distance between the center of the humidity sensing portion of the ceramic humidity sensor and the center of the facing surface of the heating resistor is The opposing distance is 1 (mm),
When the power consumption of the heating resistor is P (W), A humidity sensor device, wherein the humidity sensor device is set in a range in which