Magneto-optical recording for improved domain expansion reading
AssigneeKoninklijke Philips Electronics N.V.
InventorsCoen Adrianus Verschuren, Bart Van Rompaey, Paulus Wilhelmus Maria Blom, Jeroen Jan Lambertus Horikx, Hans Willem Van Kesteren
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Abstract
The present invention relates to magneto-optical recording technique whereby improved domain expansion reading is achieved. A mark region is recorded as a sub-mark portion and an adjacent sub-space portion, wherein the length of the sub-mark portion is set to be less than or equal to the length of the sub-space portion. Stray field variations due to different runlengths of the recording data can thus be equalized even for short channel bit lengths, while the resolution and/or power margin is improved.
Claims11
A method of recording information as a pattern of marks and spaces on a recording track of a magneto-optical recording medium, said method comprising the steps of:
- a) writing a mark by having a sub-mark portion of a mark region of said magneto-optical recording medium magnetized in a first direction substantially perpendicular to the recording surface of said recording medium and by having an adjacent sub-space portion of said mark region magnetized in a second direction which opposes said first direction;
- b) setting the length (L1) of said sub-mark portion of said mark region so as to be less than or equal to the length (L2) of said adjacent sub-space portion of said mark region in the direction of said recording track;
- and
- c) setting a ratio of said length (L2) of said sub-space portion to said length (L1) of said sub-mark portion to an integer value less than or equal to 4
- wherein the length of said mark region is determined on the basis of the following equation:
- b≧(w+L1+exp)/2,
- wherein w denotes the spatial length of a copy window for copying said mark to a read-out layer by a domain expansion technique, L1 denotes said length of said sub-mark portion, and exp denotes the time during which a bit from a recording layer can be nucleated and expanded into said read-out layer multiplied by the recording velocity.
A recording apparatus for recording information as a pattern of marks and spaces on a recording track of a magneto-optical recording medium, said apparatus comprising:
- a) writing means for writing a mark by having a sub-mark portion of a mark region of said magneto-optical recording medium magnetized in a first direction substantially perpendicular to the recording surface of said recording medium and by having an adjacent sub-space portion of said mark region magnetized in a second direction which opposes said first direction;
- and
- b) setting means for setting the length (L1) of said sub-mark portion of said mark region so as to be less than or equal to the length (L2) of said sub-space portion of said mark region in the direction of said recording track, said setting means also setting a ratio of said length (L2) of said sub-space portion to said length (L1) of said sub-mark portion to an integer value less than or equal to 4
- wherein a length of said mark region is determined on the basis of the following equation:
- b≧(w+L1+exp)/2,
- wherein w denotes the spatial length of a copy window for copying said mark to a read-out layer by a domain expansion technique, L1 denotes said length of said sub-mark portion, and exp denotes the time during which a bit from a recording layer can be nucleated and expanded into said read-out layer multiplied by the recording velocity.
A magneto-optical recording medium on which information is recorded on a recording track as a pattern of marks and spaces, wherein a mark region comprises a sub-mark portion magnetized in a first direction substantially perpendicular to the recording surface of said recording medium and a sub-space portion magnetized in a second direction which opposes said first direction, and wherein the length (L1) of said sub-mark portion is less than or equal to the length of said sub-space portion in the direction of said recording track, wherein a ratio of said length (L2) of said sub-space portion to said length (L1) of said sub-mark portion to an integer value less than or equal to 4, and wherein a length of said mark region is determined on the basis of the following equation:
- b≧(w+L1+exp)/2,
- where w denotes the spatial length of a copy window for copying said mark to a read-out layer by a domain expansion technique, L1 denotes said length of said sub-mark portion, and exp denotes the time during which a bit from a recording layer can be nucleated and expanded into said read-out layer multiplied by the recording velocity.
Dependencies are inferred from the claim text.