JPH03154301A - Dew-formation sensitive element - Google Patents

Abstract

PURPOSE:To increase response speed by constituting the title element with an insulation substrate, a pair of counter electrodes which are provided on the upper surface of the insulation substrate, and a specific dew-formation sensitive film which is provided on the opposing electrode. CONSTITUTION:A pair of counter electrodes 2a and 2b of silver and a dew- formation sensitive film 3 are placed on one surface of an insulation substrate 1 consisting of alumina, etc., and lead wires 4a and 4b are connected to the counter electrodes 2a and 2b by soldering, where the dew-formation sensitive film 3 scatters carbon powder to acrylic monomer resin and contains 0.1-0.4wt.% diaminodiphenylmethane as a curing agent, thus increasing response speed without reducing strength of the dew-formation sensitive film 3.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a dew condensation sensitive element used in, for example, a video tape recorder (VTR) and the like to detect a condensation state or the like.

BACKGROUND OF THE INVENTION In recent years, trouble μ caused by dew condensation on VTR cylinders, automobile window glasses, building materials, and other precision instruments has become a problem, and there has been a growing demand for dew condensation sensitive elements as a countermeasure.

In particular, recent home VTR cameras have become lightweight and compact, and can be easily used both indoors and outdoors. Against this background, problems with condensation have begun to occur more frequently than in the conventional case where devices were fixed in one place. Therefore, it has become desirable for such household VTR camera cameras to have dew condensation sensitive elements that can detect dew condensation as quickly as possible.

The entire structure of a conventional dew condensation sensitive element will be explained with reference to FIG.

FIG. 3 is a partially exploded perspective view of a conventional dew condensation sensing element.

In FIG. 3, reference numeral 1 denotes an insulating substrate made of alumina or the like, with a pair of silver opposing electrodes 2m on one surface.

2b and a condensation N sensitive membrane 3 are arranged. Opposing′fM
, g 2 a and 2 b have Riet lines 4a and 4b, respectively.
;A: Connected by solder.

The operation of the dew condensation sensitive element configured as described above will be described below. This dew condensation sensitive element is made by applying and baking a paste made of a mixture of conductive carbon powder and acrylic resin that expands when it contains water onto an alumina substrate 1 on which a counter electrode such as abrasive silver is arranged. The principle is that when dew condenses, the resin swells, increasing the distance between carbon particles and increasing electrical resistance. This change in resistance value is reflected through the lead wire 4a through the opposing type W21L and 2b'f-.
.

4b.

The dew condensation sensitive film 3 contains 0.5% by weight or more of a hardening agent as described above in order to increase the peel strength against the alumina substrate 1.

Problems to be Solved by the Invention In the conventional configuration, a large amount of diaminodiphenylmethane is contained as a curing agent.

Although the acrylic resin has the advantage of high peel strength against the alumina substrate, it does not expand quickly even when the acrylic resin absorbs water, resulting in a disadvantage that the response speed of the condensation sensitive element is slow.

Means for Solving the Problems In order to solve the above problems, the present invention provides an insulating substrate, at least a pair of opposing electrodes provided on the upper surface of the insulating substrate,
It consists of a dew condensation sensitive film provided on the counter electrode, and the dew condensation sensitive film is made by dispersing diaphragm powder in an acrylic monomer resin and contains diaminodiphenyl meta 720.1% to 0.4% by weight as a hardening agent. It is more than just what you are doing.

Effect of the present invention In the material composition conventionally used, diaminodiphenylmethane added as a curing agent is added to 0.1
% to 0.4% by weight, thereby making it possible to obtain a dew condensation sensitive element with increased response speed. That is, when the amount of the curing agent diaminodiphenylmethane added is 0.1% to 0.4% by weight, the conventional
The response time, which used to be 6 seconds, has been accelerated to 1 to 2 seconds. Further, when examining the surface condition H such as the peel strength of the moisture-sensitive film for these samples, it was found that they were equivalent to conventional ones.An example of the present invention will be described below.

A polymer resin was obtained by dissolving 2-hydroxyethyl methacrylate and glycidyl methacrylate (cell ratio 1s:1) in 2,ethyl cellosolve and reacting with azobisisobutyronitrile. This obtained moisture sensitive resin 60g K acetylene black carbon 2.5
g, Diaminodife and Lumethane 0.20 g (0,4
% by weight) and benzyl alcohol/I/16 g were kneaded using a three-roll mill to form a paste. Next, this moisture sensitive agent was applied onto an insulating substrate on which comb-shaped carbon electrodes had been formed in advance, and baked at 100'C for 60 minutes to form a moisture sensitive film.

FIG. 1 is a diagram showing the change in element resistance when the dew condensation sensitive element is placed from a normal temperature and normal humidity state to a high temperature and high humidity state (60'C, 100% I'll). The time required for the element resistance to reach 100 to 42 after the dew condensation sensitive element is turned on is called the response speed. FIG. 2 shows the relationship between the amount of the curing agent diaminodiphenylmethane contained in the dew condensation sensitive element and the response speed. From the figure: 0.1% by weight
It can be seen that in the range of 0.4% by weight, the response speed of 5 to 6 seconds when conventionally added at 0.5% by weight or more has been accelerated to 1 to 2 seconds.

Effects of the Invention As described above, according to the present invention, diaminodiphenylmethane to, l1tffi% to 0.4ml1ff is used as a curing agent.
By containing i%, the response speed can be increased without reducing the strength of the condensation sensitive membrane.
A highly functional dew condensation sensitive element can be provided.

[Brief explanation of the drawing]

Figure 9 $1 shows the change in element resistance when a dew condensation sensitive element is placed from a normal temperature and humidity state to a high temperature and high humidity state (60°C, 100% RH). FIG. 3 is a partially fragmented perspective view of a conventional dew condensation sensitive element.

Claims (1)

[Claims] It consists of an insulating substrate, at least a pair of counter electrodes provided on the upper surface of the insulating substrate, and a dew condensation sensitive film provided on the counter electrode, the dew condensation sensitive film having carbon powder dispersed in an acrylic monomer resin, A dew condensation sensitive element containing 0.1% to 0.4% by weight of diaminodiphenylmethane as a curing agent.