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US 8,568,890 B2Granted
Watch cover glass
AssigneeCitizen Holdings Co., Ltd.
InventorsYasushi Murata, Koutarou Takazaki
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AssigneeCitizen Holdings Co., Ltd.
InventorsYasushi Murata, Koutarou Takazaki
Estimating the term…
A watch cover glass having high hardness and excellent abrasion, and also having flaw resistance and antireflection function even after being used for a long period of time. The watch cover glass comprises a transparent substrate and, provided on at least one surface of the substrate, an antireflection film having a lamination structure that a SiON film (SiO2 and Si3N4 mixed film) and a Si3N4 film are laminated and the outermost layer is the SiON film. Accordingly, the proper antireflection effect can be obtained, the hardness of the antireflection film is increased and the abrasion resistance is remarkably increased. As a result, even after being used for a long period of time, the surface of the antireflection film is not finely flawed and is not peeled off, and it hardly occurs that the hands or dial plate are invisible due to surface mist and the antireflection function can be maintained.
A watch cover glass comprising a transparent substrate having a front surface and a back surface and, provided on at least one surface of the substrate, an antireflection film obtainable by laminating a SiO2 and Si3N4 mixed film and a Si3N4 film alternately one after another in the total of 4 or more layers and having the SiO2 and Si3N4 mixed film in the outermost layer,
A process for producing a watch cover glass comprising a transparent substrate having a front surface and a back surface and, provided on at least one surface thereof, an antireflection film, which process comprises:
Dependencies are inferred from the claim text.