JPH02280041A - condensation sensor - Google Patents

Abstract

PURPOSE:To prevent the infiltration of water droplet and to appropriately detect dew condensation by arranging a dew condensation sensor main body inside a resin package having a recessed part and providing a cover plate having a hole on the outer surface of the package in no contact with the sensor main body. CONSTITUTION:The dew condensation sensor main body 3 where a pair of electrodes for detecting the dew condensation by the change of electric resistance is coated with a moisture sensitive film 6 is provided in the resin package 2 having the recessed part. The cover plate 7 having the hole is provided on the outer surface of the package 2 and the sensor main body 3 is allowed not to be in contact with the coating plate 7. The hole of the cover plate 7 is formed in such a size that the water droplet can not infiltrate from the relation of the surface tension of water or gravity. Therefore, the dew condensation is detected by the film 6 through the hole of the cover plate 7 and the water droplet caused by gathering dew drops is prevented from infiltrating in the sensor main body 3. Thus, malfunction is prevented and the dew condensation is appropriately detected.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a dew condensation sensor mounted on a VTR, DAT, or the like.

BACKGROUND OF THE INVENTION Conventionally, the structure of a dew condensation sensor used in VTRs, DATs, etc. is such that electrodes are formed on a ceramic substrate and a moisture-sensitive material is coated thereon. VTRs used not only indoors but also outdoors, such as camera-integrated VTRs and 8mm video cameras, are becoming increasingly smaller, so recently, compact dew condensation sensors made using semiconductor technology have been developed.

For example, "Sensor Technology" Vol. 8 No. 6 (April 2, 1986)
There is a thin film dew condensation sensor shown on pages 244 to 246 of the publication published by Information Research Association Co., Ltd. on the 6th.

In this thin film condensation sensor, as shown in FIG. It's touchable. In addition, 4 in the figure is the resin molded part 2.
This is a part in which resin is injected into a part of the recessed part, and is used to fix a gold wire for connecting the electrode 9 and the lead 5.

Problems to be Solved by the Invention However, handheld VTRs and DATs such as camera-integrated VTRs and 8mm video cameras that are equipped with small dew condensation sensors produced using the above-mentioned semiconductor technology are not suitable for VTRs.
If you hold the sensor with condensation and shake it, depending on where the sensor is installed, large water droplets formed by small particles may move from the outside and enter the sensor's package. Sometimes. For this reason,
Even if the dew on the surface of the cylinder where condensation should be detected disappears, the water droplets that have entered the sensing part of the condensation sensor remain attached, and the dew sensor does not issue a dew removal signal until the water droplets evaporate and completely disappear. There were problems such as tripping, malfunctions, etc.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a dew condensation sensor that can appropriately detect dew condensation.

Means for Solving the Problems To achieve this object, the dew condensation sensor of the present invention has a dew condensation sensor body covered with a moisture-sensitive film with a pair of electrodes facing each other, arranged inside a resin pancake having a recessed part,
A cover plate having a through hole is provided on the outer surface of the resin package, and the dew condensation sensor body and the cover plate are configured to be in non-contact.

Function: With this configuration, even if water droplets adhere to the cover plate, the surface tension of the water, the water's own weight, and the size of the through holes in the cover plate prevent the water droplets from entering the inside of the package. This allows for proper humidity detection.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of a main part of a package structure of a dew condensation sensor according to a first embodiment of the present invention, and FIG. 2 is a sectional view thereof. In the figure, 1 is a mounting part for fixing to the equipment, 2 is a resin cover, a cage, 3 is a dew condensation sensor main body, 4 is a resin, 6 is a lead, 6 is a moisture sensitive membrane, and 7 is a cover plate. This covering plate 7 has a large number of through holes,
It is molded from resin.

A dew condensation sensor main body 3 is constructed by covering a pair of electrodes arranged to detect a dew condensation state based on a change in electrical resistance with a moisture sensitive film 6, and includes a resin package 2 having a concave portion.
A covering plate 7 having a through hole is placed on the outer surface of the resin package 2 by a snap method. In this case, the dew condensation sensor body 3 is connected to the resin package 2
The cover plate 7 is fixed in the concave portion and is not in contact with the cover plate 7.

Further, the dimensions of the through holes in the cover plate 7 are such that water droplets cannot pass through them, but air and moisture can flow through them, due to the surface tension and weight of the water.

With the above configuration, the dew condensation sensor of this embodiment can be used on a VTR or D
When preparing for AT, etc., the state of dew condensation can be detected with a moisture-sensitive membrane through the through holes in the cover plate 7. At the same time, the cover plate 7 can prevent water droplets due to condensation from penetrating onto the dew condensation sensor main body 3.

Note that the present invention is not limited to the above-mentioned embodiment, but as shown in the perspective view of FIG. effect can be obtained.

Effects of the Invention By carrying out the present invention, a small dew condensation sensor produced using semiconductor technology can be used in a handy VTR or DAT.
To provide an excellent package structure for a dew condensation sensor that eliminates the problem of malfunction caused by large water droplets generated by movement of dew entering the cage of the dew condensation sensor when installed in a dew sensor, and enables proper dew condensation detection. I can do it.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a dew condensation sensor showing a first embodiment of the present invention, and FIG. 21 is a sectional view thereof. FIG. 3 is a perspective view showing another embodiment, and FIG. 4 is a perspective view of the appearance of a conventional dew condensation sensor. 1... Mounting part, 2... Resin package, 3... Condensation sensor body, 4... New Year's visit, 6
...IJ-to, 6...moisture-sensitive membrane, 7.
... Cover plate, 8 ... Net, 9 ... Electrode. Name of agent: Patent attorney Shigetaka Awano and one other person

Claims (1)

[Claims] A dew condensation sensor main body, which is covered with a moisture-sensitive film with a pair of electrodes facing each other, is disposed inside a resin package having a recess, and a cover plate having a through hole is provided on the outer surface of the resin package, and the dew condensation sensor and the A dew condensation sensor characterized by being made in a non-contact manner with a cover plate.