JPH0341345A - Weight and dew condensation sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a sensor that can detect weight and dew condensation with a single element, and is used in cooking appliances and the like.

BACKGROUND ART Conventionally, as shown in Japanese Patent Publication No. 1-1352, a weight sensor has been used, as shown in Japanese Patent Publication No. 1-1352.
A capacitive weight sensor is known that is fixed by an adhesive layer and further has electrode films formed on mutually opposing surfaces of a pair of insulating substrates. Weight is detected by using one of a pair of insulating substrates as a diaphragm, and detecting deformation of the diaphragm as a change in capacitance when weight is applied to the diaphragm.

In addition, there are various types of dew condensation sensors, but a typical temperature sensor is the "dew condensation sensor" (National Technical Report, Vo124. No. 3197843).
A dew condensation sensor is known in which a dew condensation detection film made of a water-absorbing resin and carbon is formed on an insulating substrate, as shown on page 6-443, 10,000 yen, et al. Condensation is detected by utilizing the fact that the impedance of the dew condensation detection film changes due to condensation.

As described above, sensors that can detect weight and dew condensation separately are known, but there are no sensors that can detect both with a single element.

Problems to be Solved by the Invention For example, when detecting the weight of food using a cooking device such as a microwave oven, it is necessary to prevent malfunctions due to condensation in order to detect the weight with sufficient accuracy. However, since no sensor is known that can detect weight and dew condensation with a single element, two separate sensors had to be used to prevent this malfunction.

For this reason, there was a problem that humidity compensation became complicated and the cost became high.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a weight condensation sensor that can detect weight and dew condensation with a single element.

Means for Solving the Problems The weight condensation sensor of the present invention includes a first insulating substrate, a first electrode film formed on the surface of the first insulating substrate, and a fixed electrode film opposite to the first electrode film. a second insulating substrate separated by an interval of and fixed by an adhesive layer; a second electrode film formed on the surface of the second insulating substrate to face the electrode film;
a pair of third insulating substrates formed on the other surface of the second insulating substrate;
This configuration includes an electrode film and a dew condensation detection film electrically connected to the pair of third electrode films.

The weight is detected by using the first insulating substrate as a diaphragm and detecting the deformation of the diaphragm as a change in capacitance between the first electrode film and the second electrode film when weight is applied to the diaphragm. can. Further, since the resistance value of the dew condensation detection film formed on the other surface of the second insulating substrate changes due to dew condensation, dew condensation can be detected by detecting the change in the resistance value between the pair of third electrode films.

Embodiment Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings. FIG. 1 is a sectional view of the weight condensation sensor of the present invention.

A first electrode film 2 was formed on the surface of the first insulating substrate 1, and a second electrode film 4 was formed on one surface of the second insulating substrate 3. Thereafter, the first insulating substrate 1 and the second insulating substrate 3 were fixed at a constant interval using the adhesive layer 5, with the first electrode film 2 and the second electrode film 4 facing each other. . Next, a pair of electrode films 6 and a dew condensation detection film 7 were formed on the other surface of the second insulating substrate 3. An alumina plate, a glass plate, etc. are used as the first and second insulating substrates 1.3.

A first electrode film 2, a second electrode film 4, and a pair of third electrode films 6
As the material, a fired conductive thick film or thin film, a vapor-deposited or sputtered conductive thin film, etc. are used. As the adhesive layer 5,
A fired glass film, a resin film, etc. are used. Furthermore, a conductive moisture absorption film is used as the dew condensation detection film 7.

The thickness of the alumina insulating substrate 1 is approximately 0.6 mm, the opposing area of the first electrode film 2 and the second electrode film 4 is approximately 2.5 mm, and the thickness of the contact layer 6 (the thickness of the alumina insulating substrate 1 and the temperature-sensitive (distance between boards 3)
is approximately 50 μm, and as shown in FIG. 2, a load is applied to the center of the aluminum insulating substrate 1, and the capacitance value between the first electrode film 2 and the second electrode film 4 is measured. did. Load is Okg
, 2kg, 4kg, the capacitance value is approximately 51
pF, about 54.5PF, and about 60pF, and the capacitance value increased as the load increased. However, for example, if the load is kept constant at Okg and the surrounding relative humidity exceeds 100%, and dew condensation water begins to adhere to the surfaces of the first electrode film 2 and second electrode film 4, the capacitance value will decrease. It increased by more than 1%. This increase in capacitance value corresponds to a weight measurement error of 200 g or more, so when used in cooking appliances such as microwave ovens,
Easy to cause malfunction. In such cases, it is necessary to detect dew condensation to prevent malfunctions.

The conductive moisture absorption film is useful as the dew condensation detection film 7 because its resistance value changes rapidly under dew condensation conditions.

For example, when a pair of comb-shaped third electrode films 6 and a conductive hygroscopic film 7 in which carbon particles are dispersed in a hygroscopic resin such as nylon are formed on the other surface of the second insulating substrate 3, the resistance value is It was less than 20 Ω at relative humidity of 94% or less, but rapidly increased to more than 200 kΩ at 100% relative humidity. Condensation can be detected from this change in resistance value.

As described above, the weight condensation sensor of the present invention can detect weight from the capacitance value with a single element, and can also detect dew condensation from the resistance value of the dew condensation detection film 7.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained.

(1) Weight and dew condensation can be measured simultaneously with a single element.

(2) Therefore, malfunctions due to errors in weight measurement due to dew condensation can be prevented.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a weight temperature sensor showing an embodiment of the present invention, and FIG. 2 is a sectional view showing deformation of a diaphragm during weight measurement. 1... First insulating substrate, 2... First electrode film, 3... Second insulating substrate, 4...
2nd electrode film, 5... adhesive layer, 6... a pair of third electrode films, 7... dew condensation detection film.

Claims (3)

[Claims] (1) a first insulating substrate; a first electrode film formed on the surface of the first insulating substrate; and a first electrode film facing the first electrode film, separated from the first electrode film at a constant interval, and fixed by an adhesive layer. a second insulating substrate; a second electrode film formed on a surface of the second insulating substrate to face the electrode film; and a pair of third electrode films formed on the other surface of the second insulating substrate.
A weight condensation sensor comprising an electrode film and a dew condensation detection film electrically connected to the pair of third electrode films. (2) The weight condensation sensor according to claim 1, wherein the dew condensation detection film is composed of a film whose impedance changes depending on relative humidity. (3) The weight condensation sensor according to claim 2, wherein the dew condensation detection film is composed of a water-supplying resin and carbon particles.