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US 4,902,584 AGranted
Optical recording medium
AssigneeTDK Corporation
InventorsKenji Uchiyama, Hideki Ishizaki, Hajime Utsunomiya, Suguru Takayama
Life of this patent
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Abstract
An optical recording medium comprising a recording layer on a substrate and a protective layer formed adjacent to the upper or lower surface of the recording layer is more durable and corrosion resistant when the protective layer has a composition comprising silicon, a divalent metal such as Ba, Ca or Sr, oxygen, and nitrogen. An intermediate layer containing silicon, a metal or metalloid such as aluminum or lanthanum, oxygen and nitrogen is formed between the protective layer and the recording layer.
Claims11
A magneto-optical recording medium comprising:
- a substrate,
- a recording layer formed on the substrate, said recording layer having upper and lower surfaces disposed remote from and adjacent to the substrate, respectively, and
- at least one protective layer formed adjacent to the upper or lower surface of said recording layer, said protective layer comprising silicon, at least one divalent metal selected from the group consisting of barium, calcium, magnesium and strontium, oxygen, and nitrogen wherein the silicon is present in the protective layer in an atomic ratio of silicon to the total of silicon and divalent metal of from about 3:10 to about 9:10, wherein the oxygen is present in the protective layer in an atomic ratio of oxygen to the total of oxygen and nitrogen of from about 4:10 to about 8:10.
Dependencies are inferred from the claim text.