Magneto-optical disc system and magneto-optical disc
AssigneeSony Corporation
InventorsItaru Suzuki, Hajima Yano, Hiroyuki Wakasugi, Kaoru Nakajima
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Abstract
A magneto-optical disc system and a medium used therewith are disclosed in which a magneto-optical disk having a magneto-optical recording layer on one major surface with a protective film formed on said magneto-optical recording layer, on which a magnetic head is slid, and an optical system having a focus servo mechanism on the other surface. The focus servo mechanism of the optical system satisfies a certain condition to avoid any focal blank.
Claims2
A magneto-optical disc system, comprising a magneto-optical disc having a magneto-optical recording layer on one major surface thereof, with a protection film having a projection formed on said magneto-optical recording layer, and an optical system having a focus servo mechanism arranged on the other surface of the magneto-optical disc, characterized in that
- the focus servo mechanism of the optical system satisfies the following formula 1:
- ##EQU13## h:
- height of the projection on the protection film surface (m) r:
- radius of the projection on the protection film surface (m)
- m.sub.D :
- mass of the magneto-optical disc (kg)
- m:
- mass of the magnetic head (kg)
- Vx:
- linear-velocity (m/second) of the focus servo mechanism relative to the disc
- fc:
- servo frequency (Hz)
- y:
- focal depth of the object lens (.mu.m).
A magneto-optical disc, comprising a magneto-optical layer on one major surface thereof, with said magneto-optical layer covered by a protection film having a projection, along which a magnetic head is slid, and an optical system having a focus servo mechanism on the other surface, characterized in that
- no projection which does not satisfy the following formula 1 exists on the protection film surface:
- ##EQU14## h:
- height of the projection on the protection film surface (m) r:
- radius of the projection on the protection film surface (m)
- m.sub.D :
- mass of the magneto-optical disc (kg)
- m:
- mass of the magnetic head (kg)
- Vx:
- linear-velocity (m/second) of the focus servo mechanism relative to the disc
- fc:
- servo frequency (Hz)
- y:
- focal depth of the object lens (.mu.m).
Dependencies are inferred from the claim text.