Claims
- 1. A method of reducing a byte error rate of data reproduced from an optical disc arising from corrosion of a functional layer of the optical disc, comprising the steps of:
- providing a substrate;
- arranging a functional film over the substrate; and
- forming a protective film over the functional film,
- wherein the protective film has a maximum film thickness d at an outer periphery of the protective film and a mean film thickness d.sub.0 at a flat portion of the protective film on a data area of the disc which are related by
- 2d.sub.0 .ltoreq.d-d.sub.0 +40 mm,
- and wherein a radius of curvature of the protective film at the outer periphery of the film is equal to or greater than a radius of curvature of a portion of a sliding contact surface of a magnetic head device radially extending toward said outer periphery of said disc from the reading portion of the magnetic head device, and wherein the radius of curvature of said protective film at said outer periphery is equal to or greater than 12.48 mm.
- 2. The method of claim 1, further comprising the step of recording data on the functional layer when a section of the outer portion of the sliding contact surface overlaps a portion of the protective film between the flat portion and an outer edge of the disk.
- 3. The method of claim 1, further comprising the step of reading data stored at an outer most recordable radius position of the optical disk using a magnetic head device with an elongated sliding contact surface.
- 4. The method of claim 3, further comprising the step of positioning a magnetic head element of the magnetic head device substantially over a sliding contact point when said reading step is being performed.
- 5. The method of claim 1, wherein the maximum film thickness d of the protective film at the outer periphery and the mean film thickness d.sub.0 of the protective film at the flat portion are related by
- 2d.sub.0 .ltoreq.d.ltoreq.d.sub.0 +40.mu.m.
- 6. A method of reducing a byte error rate of data reproduced from an optical disc arising from corrosion of a functional layer of the optical disc, comprising the steps of:
- providing a substrate;
- arranging a functional film over the substrate; and
- forming a protective film over the functional film,
- wherein the protective film has a maximum film thickness d at an outer periphery of the protective film and a mean film thickness d.sub.0 at a flat portion of the protective film on a data area of the disc which are related by
- 2d.sub.0 .ltoreq.d.ltoreq.d.sub.0 +40 mm,
- and wherein a space over a curved portion of the protective film between the flat portion and the outer edge of the disk is occupied by a first section of a sliding contact surface of a magnetic head device when a second section of the sliding contact surface contacts the flat portion.
- 7. The method of claim 6, wherein the maximum film thickness d of the protective film at the outer periphery and the mean film thickness d.sub.0 of the protective film at the flat portion are related by
- 2d.sub.0 .ltoreq.d.ltoreq.d.sub.0 +40.mu.m.
- 8.
- 8. A method of reducing a byte error rate of data reproduced from an optical disc arising from corrosion of a functional layer of the optical disc, comprising the steps of:
- providing a substrate;
- arranging a functional film over the substrate; and
- forming a protective film over the functional film,
- wherein the protective film has a maximum film thickness d at an outer periphery of the protective film and a mean film thickness d.sub.0 at a flat portion of the protective film on a data area of the disc which are related by
- 2d.sub.0 .ltoreq.d<d.sub.0 +40 mm,
- and wherein a space over a curved portion of the protective film between the flat portion and the outer edge of the disk is occupied by a section of a sliding contact surface of a magnetic head device, said section of said sliding contact surface having a radius of curvature less than the radius of curvature of the curved portion of the protective film, when an outer most recordable area of the functional film is magnetically communicating with a magnetic recording section of the magnetic head device.
Priority Claims (2)
Number |
Date |
Country |
Kind |
3-359087 |
Dec 1991 |
JPX |
|
4-314331 |
Oct 1992 |
JPX |
|
Parent Case Info
This is a divisional of application Ser. No. 08/908,739, filed Aug. 7, 1997, which is a continuation of Ser. No. 07/994,662 filed Dec. 22, 1992 now U.S. Pat. No. 5,916,638.
US Referenced Citations (6)
Foreign Referenced Citations (4)
Number |
Date |
Country |
60-101720 |
Jun 1985 |
JPX |
61-133067 |
Jun 1986 |
JPX |
62-289946 |
Dec 1987 |
JPX |
63-191335 |
Aug 1988 |
JPX |
Divisions (1)
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Number |
Date |
Country |
Parent |
908739 |
Aug 1997 |
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Continuations (1)
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Number |
Date |
Country |
Parent |
994662 |
Dec 1992 |
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