Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
1997-02-07
2001-04-24
Sikes, William L. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C065S030140
Reexamination Certificate
active
06222604
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a display device and a method of manufacturing the same, and more particularly, to a display device which has been improved in the strength of impact-resistant properties or the like and a method of manufacturing the same.
A schematic structure of a conventional display device will be described below. A sodium passivation film made of SiO
2
is formed on the surface of a glass substrate made of soda-lime glass, borosilicate glass, or the like, and further a transparent electrode made of film-like ITO grown by a method such as evaporation or sputtering is formed thereon while being patterned. Two glass substrates, on the surface of each of which the sodium passivation film and the transparent electrode are sequentially formed as described above, are bonded to each other with a sealing agent so that they are opposite to each other, and a display material such as a liquid crystal or an electrochromic material is enclosed in the gap between the glass substrates to form the display device.
Since such a display device is excellent in portability and consumes little electric power, contrary to a CRT or the like, it is widely used at present for a digital watch, a display for a computer, and so on.
However, since a highly transparent substrate is desired for such a flat panel display, a glass substrate is used in the existing circumstances. However, the glass substrate has a defect that it is liable to break because it is made of glass.
Especially, since the flat panel display is often used for a portable electric equipment, it is required to be strong against impact of drop. On the other hand, since the portable electric equipment is desired to be light, thin, short, and small, the thickness of the glass substrate is required to be thin, which results in deterioration in the strength. That is, the display device has such a contradictory problem.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to realize a display device which has sufficient strength even if the thickness of a glass substrate is made thin.
In order to solve the problem, according to the present invention, in a display device in which a pair of glass substrates, on the surface of each of which an electrode is formed, are opposite to each other, and a display material is enclosed in the gap between the substrates, a chemically reinforced layer having a thickness of not larger than 20 &mgr;m is formed on the surface of at least one of the glass substrates. Further, a method of manufacturing the display device comprises a chemical reinforcing treatment step of immersing a glass substrate in a solution or a molten solution of salt containing positive ions having an ion radius larger than that of sodium to form a chemically reinforced layer having a thickness of not larger than 20 &mgr;m on the glass substrate.
Still further, a method of manufacturing the display device comprises the steps of immersing a glass substrate in a solution or a molten solution of salt containing positive ions having an ion radius larger than that of sodium, forming a chemically reinforced layer having a thickness of not larger than 20 &mgr;m on the glass substrate, forming a plurality of cells composed of a pair of glass substrates using the glass substrate on which the chemically reinforced layer is formed, scratching the surface of the glass substrate on which the chemically reinforced layer is formed, and cutting the glass substrate to divide the cells into individual ones.
In the display device according to the present invention, sodium atoms on the surface of the glass substrate are replaced with atoms having an ion radius larger than that of sodium, so that the substrate is chemically reinforced and has an improved mechanical strength.
Further, the strength of the glass of the display device can be improved by merely adding a step of immersing the glass substrate in the solution or molten solution containing the positive ions having an ion radius larger than that of sodium, which is very simple. Further, according to this method, the thickness of the chemically reinforced layer can be easily controlled by adjusting an immersion time or the like, and the device can be formed under such a condition that working of glass cutting or the like can be carried out even after reinforcement of the substrate.
Still further, in the case where glass having a thickness of not larger than 2 mm, if the thickness of the chemically reinforced layer is not larger than 20 &mgr;m, the display device having sufficient mechanical strength can be easily obtained without extremely complicating a conventional step of glass cutting or the like.
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Kumai Sachiko
Shimada Kazuo
Suginoya Mitsuru
Adams & Wilks
Nguyen Dung
Seiko Instruments Inc.
Sikes William L.
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