JPS6266150A - Dew-drop sensor - Google Patents

Abstract

PURPOSE:To obtain a dew-drop sensor by providing a pair of electrodes having a surface worked to a rough surface, on a film-shaped insulating substrate, and providing a hydrophilic group layer on the surface of the electrode. CONSTITUTION:Opposed electrodes 9, 10 of a Cu-Ni alloy are formed in a shape of the teeth of a comb on the surface of an epoxy resin film whose thickness is 2mu. Next, a minute uneven part is formed by corroding and removing only Cu by a water solution of FeCl, and a hydrophilic polymer or Na salt of a higher fatty acid, etc. 11 are stuck. This dew-drop sensor 7 and an ammeter 15 are connected in series to a power source 14, and the dew-drop quantity is detected as a variation of a resistance value of the sensor. According to this constitution, the water content condensed on the sensor does not become a water droplet but becomes a smooth film shape and spreads uniformly on the surface of the sensor, and collects in a gap 12 between the electrodes. Therefore, a contact area between the electrodes 9, 10 and the condensed water content increases, the measurement can be executed with a high sensitivity, and the structure is extremely simple.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a dew condensation sensor that measures the amount of dew condensation based on a change in electrical resistance between electrodes formed facing each other on a substrate.

<Prior Art> In vehicles, houses, industrial facilities, etc., it is sometimes necessary to detect whether or not moisture in the air has condensed for air conditioning or to protect equipment that dislikes condensation. Conventionally, dew condensation sensors have been known that determine dew condensation by forming a pair of electrodes on a substrate and detecting changes in electrical resistance between the two electrodes due to moisture condensing on the substrate. This tends to condense in the form of water droplets on the electrode, and even though moisture is attached to the electrode, it may not be detected, or a change in resistance value cannot be obtained in proportion to the amount of condensation. First, there was a drawback that the measured values varied widely.

For example, as shown in FIG. 1, according to such a known dew condensation sensor 1, electrodes 3.
Since it has a water-retaining surface, moisture in the condensed air becomes granular on the surface of the electrode 3.4 or in the inter-electrode gap 5. Firstly, the measurement sensitivity is poor; Second, the size and location of the water droplets 6 vary depending on the surface condition of the electrode, resulting in large variations in measurement.

Therefore, as disclosed in, for example, Japanese Patent Laid-Open No. 53-48792, a technique has been proposed in which a large number of electrodes are provided with different gaps between the electrodes to obtain an output that is compatible with dew condensation. However, the detection output changes stepwise according to the amount of dew condensation, and it is not always possible to obtain a satisfactory measurement accuracy.

Therefore, it is conceivable to form a moisture-sensitive film on the electrode surface and detect the change in resistance value between the electrodes due to moisture moistening the moisture-sensitive film, but as pointed out in JP-A-56-70449@. Another problem is that the moisture that wets the moisture-sensitive membrane remains even after the condensation condition is resolved, and the sensor becomes unusable until the moisture inside the moisture-sensitive membrane dries naturally. It has been proposed to actively remove such moisture by attaching a heater to the sensor, but there are disadvantages in that the humidity sensor deteriorates due to heating and the structure becomes complicated.

<Problems to be Solved by the Invention> In view of the drawbacks of the prior art, the main object of the present invention is to provide a dew condensation sensor that has a single Tl structure and can generate an output proportional to the amount of dew condensation. It is about providing.

<Means for Solving the Problems> According to the present invention, the present invention provides a substrate made of a film-like insulating material that can be attached to a measurement surface, and a roughened surface laminated on the substrate. This is achieved by providing a dew condensation sensor characterized by comprising: a pair of electrodes having the following properties; and a hydrophilic base layer deposited on the surface of the electrodes.

<Function> Since the hydrophilic base layer is coated on the electrode, the condensed water does not turn into particles, but forms a water film that uniformly covers the electrode surface and the gap between the electrodes, resulting in an output proportional to the amount of dew condensation. Moreover, when the dew condensation condition is resolved, the moisture on the dew condensation sensor immediately evaporates, eliminating the above-mentioned disadvantage. Further, by making the substrate made of a film-like material that can be attached to the measurement surface, it becomes possible to accurately detect the dew condensation conditions on the measurement surface.

<Embodiments> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 and 2 show a condensation sensor according to the invention.

The substrate 8 is made of an epoxy resin film having a thickness of about 2 microns, and a pair of electrodes 9 and 10 are laminated on the surface thereof so as to face each other in a comb-like shape. This electrode is made of, for example, a copper-nickel alloy, and only the copper is selectively etched with an aqueous solution of ferric chloride to form fine irregularities on its surface. A hydrophilic base layer 11 made of a hydrophilic polymer or a sodium salt of a higher fatty acid is adhered to the surface of the electrode 9.100 which has been roughened in this manner.

In particular, FIG. 3 shows how to use this dew condensation sensor 7. By connecting the ammeter 15 and the dew condensation sensor 7 in series to the power supply 14, the amount of dew condensation on the dew condensation sensor can be measured by the resistance of the sensor. It can be detected as a value change, that is, a change in the current value in the ammeter 15.

According to the dew condensation sensor based on the present invention, since the substrate is made of a thin film, the thermal resistance between the measurement surface and the sensor is very small, making it possible to reduce the temperature difference between the measurement surface and the sensor electrode surface. can. Therefore, the difference between the amount of condensation on the measurement surface and the amount of condensation on the sensor surface can be reduced.
High-fidelity detection of the conditions surrounding the sensor is possible. In particular, it is preferable to provide an adhesive layer on the back side of the substrate so that it can be easily attached to the measurement surface.

Furthermore, since the electrode surface is roughened, the hydrophilic base layer 11 can be uniformly applied, and problems such as peeling of the hydrophilic base layer do not occur even after long-term use.

When moisture in the air condenses on the dew condensation sensor 6 according to the present invention, the condensed moisture does not form into water droplets, but forms a smooth film that spreads uniformly over the sensor surface and within the gap 12 between the electrodes. 24). Therefore, the contact area between the electrodes 9 and 10 and the condensed water becomes large, making it possible to perform highly sensitive measurements and to generate a change in resistance proportional to the amount of dew condensation. Furthermore, since the contact area between the electrode and water is large, measurement can be performed using a relatively low voltage, and measurement errors caused by heat generation due to the measurement current can be avoided.

The dew condensation sensor based on the present invention can be widely applied to the purpose of accurately measuring the amount of dew condensation as described above, but is especially suitable for being attached to window glass such as a windshield to detect dew condensation inside a vehicle. Are suitable.

<Effects of the Invention> As described above, according to the present invention, the amount of dew condensation can be detected with high accuracy using an extremely simple configuration, and, for example, condensation that may narrow the driver's field of vision in the vehicle interior can be detected at an early stage. It is possible to prevent dew condensation through automatic operation of air conditioners and other devices, which can be extremely effective in improving the comfort and safety of vehicle driving.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view showing a dew condensation sensor based on the prior art. FIG. 2 is a sectional view showing a dew condensation sensor according to the present invention. FIG. 3 is a plan view showing a dew condensation sensor according to the present invention. 1... Dew condensation sensor 2... Substrate 3. 4... Electrode 5... Gap 6... Water droplet 7.
... Condensation sensor 8 ... Board 9.10 ...
・Electrode 11...Hydrophilic base layer 12...Void 13・
...Water film 14...Power source 15...Ammeter patent Applicant: Honda Motor Co., Ltd. Agent: Patent attorney: Yo Oshima - 1st - Figure 2 Figure 3

Claims (2)

[Claims] (1) A dew condensation sensor that measures the amount of dew condensation based on a change in electrical resistance between electrodes formed facing each other on a substrate, comprising: a substrate made of a film-like insulating material that can be attached to a measurement surface; and a layer laminated on the substrate. A dew condensation sensor comprising: a pair of electrodes having a roughened and roughened surface; and a hydrophilic base layer deposited on the electrode surfaces. (2) The dew condensation sensor according to claim 1, wherein the electrode is made of at least two kinds of metals, and the surface thereof is roughened by selectively etching these metals.