Method of making a vehicle windshield surface hydrophilic

Details Method of making a vehicle windshield surface hydrophilic Method of making a vehicle windshield surface hydrophilic

1999-06-22

2001-05-29

Fleming, Fritz (Department: 2836)

Electricity: electrical systems and devices

Electric charging of objects or materials

C307S010100, C361S229000

Reexamination Certificate

active

06239964

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method for making surfaces hydrophilic, in particular surfaces of motor vehicle windows.
2. Prior Art
It is known that moisture striking surfaces leads to the formation of fine water droplets in the form of spherical domes due to limits of tension. Particularly on windows of motor vehicles, this impairs visibility for a vehicle driver. The droplets collecting on the surface of the vehicle window act as short focal length converging lenses, which results in a sharp increase in the percentage of scattered light, with an attendant considerable impairment to visibility. In order to eliminate the disadvantages connected with this, it is known to make the surface of motor vehicle windows hydrophilic. This should achieve the fact that the contact angle of water on this surface becomes very small and approaches zero in the borderline case of film-like wetting so that only a correspondingly very slight change in the refraction angle occurs. Usually, chemical additives are added to the wiper fluid, which should assure that windows are made hydrophilic. In addition to the undesirable side effects due to the chemical additives, this can only achieve a very incomplete, i.e. only temporarily effective result.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method of making a vehicle window, windscreen or windshield hydrophilic, so that visibility is improved during rain and similar weather conditions without using any additional chemical means.
According to the present invention the method of making the windshield, windscreen or window of the vehicle hydrophilic comprises exposing the surface of the window, windscreen or windshield to a corona discharge from at least one moving electrode that passes over the surface, especially to a corona discharge from a moving electrode connected or associated with a wiper blade of a wiper apparatus for the window, windscreen or windshield.
The method according to the invention offers the advantage over the prior art that a relatively long-lasting hydrophilization of surfaces is possible in a simple manner. By virtue of the fact that the surface is subjected to a corona discharge, an influence on the molecular structure can be produced on the surface of windows, which leads to a reduction of limits of tension between the surface and moisture striking the surface so that a much more extensive spreading of moisture droplets on the surface is possible. As a result of the much smaller contact angle connected with this, a thin film forms on the surface that has been hydrophilized by means of the corona discharge, the surface of which film extends essentially parallel to the surface of the window so that particularly when used on motor vehicle windows, there is no change in the refraction angle of transmitted light. This reduces an impairment to the vehicle driver's ability to see things.
In a preferred embodiment of the invention, the provision is made that the treatment of motor vehicle windows with a corona discharge takes place by means of a window wiper apparatus in motor vehicles, particularly by way of a window wiper rubber that functions as an electrode. As a result, it is advantageously possible to either continuously repeat the hydrophilization of the window surface with each starting of the window wiper apparatus or to repeat it at predetermined intervals within which experience has shown the hydrophilization of the surface to diminish.


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Patent Abstracts Of Japan vol. 12, No. 387 (C-536) 3234, Nov. 14, 1988 & JP 63 134053 A, Jun. 6, 1988.

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