Copy window setpoint control for domain expansion reading
First Claim
1. A calibration method for calibration of a copy window control setpoint during readout of a magneto-optical recording medium (10) comprising a storage layer and a readout layer, wherein an expanded domain leading to a readout pulse is generated in said readout layer by copying a mark region from said storage layer to said readout layer upon heating by a radiation power with the help of said external magnetic field, said method comprising the steps of:
- a) varying at least one predetermined reading parameter;
b) monitoring a data pattern reproduced during said variation step;
c) determining at least one limit value for said at least one predetermined reading parameter based on said monitored data pattern;
d) setting said at least one reading parameter to a predetermined value determined on the basis of said limit value;
e) applying a predetermined additional pattern of change to said predetermined parameter; and
f) using a characteristic value of a phase change induced to said reproduced data pattern by said additional pattern of change as said control setpoint.
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Abstract
The present invention relates to a recording medium, calibration method and apparatus for reading the recording medium, wherein the size of a spatial copy window of domain copying process is controlled by varying at least one predetermined reading parameter in response to a control information derived from a readout pulse, and by applying a predetermined additional pattern of change to said predetermined additional pattern of change to said predetermined parameter. A characteristic value, e.g. phase amplitude, of a phase change imposed on a reproduced data pattern by said additional pattern of change is used as a reference setpoint for copy window control. The data pattern reproduced by said reading apparatus may be monitored in order to determine a predetermined optimum value of the at least one predetermined parameter and to detect the characteristic value of said imposed phase change when the optimum value of said reading parameter is applied. As an alternative, the characteristic may be stored on the recording medium. A setpoint signal is provided thereby which can be accurately measured. Moreover, if the setpoint value is stored as an intrinsic property on the recording medium, the number of calibration operations can be significantly reduced.
10 Citations
26 Claims
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1. A calibration method for calibration of a copy window control setpoint during readout of a magneto-optical recording medium (10) comprising a storage layer and a readout layer, wherein an expanded domain leading to a readout pulse is generated in said readout layer by copying a mark region from said storage layer to said readout layer upon heating by a radiation power with the help of said external magnetic field, said method comprising the steps of:
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a) varying at least one predetermined reading parameter;
b) monitoring a data pattern reproduced during said variation step;
c) determining at least one limit value for said at least one predetermined reading parameter based on said monitored data pattern;
d) setting said at least one reading parameter to a predetermined value determined on the basis of said limit value;
e) applying a predetermined additional pattern of change to said predetermined parameter; and
f) using a characteristic value of a phase change induced to said reproduced data pattern by said additional pattern of change as said control setpoint. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A reading apparatus for reading from a magneto-optical recording medium (10) comprising a storage layer and a readout layer, wherein an expanded domain leading to a readout pulse is generated in said readout layer by copying a mark region from said storage layer to said readout layer upon heating by a radiation power with the help of an external magnetic field, said apparatus comprising:
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a) control means (30, 32) for controlling the size of a spatial copy window of said copying process by varying at least one predetermined reading parameter in response to a control information derived from said readout pulse;
b) change means (32) for applying a predetermined additional pattern of change to said at least one predetermined parameter; and
c) calibration means (290) for using a characteristic value of a phase change induced to a reproduced data pattern by said additional pattern of change as a reference setpoint for said control means (30, 32). - View Dependent Claims (14, 15, 16, 17, 18, 19)
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- 20. A recording medium comprising a storage layer and a readout layer, wherein an expanded domain leading to a readout pulse is generated in said readout layer by copying a mark region from said storage layer to said readout layer upon heating by a radiation power with the help of an external magnetic field, said recording medium (10) having written thereon a calibration information defining a reference setpoint for controlling the size of a spatial copy window of said copying process.
Specification