Radiation power and/or field control of domain expansion recording medium

Abstract

The present invention relates to a method, an apparatus and a record carrier for controlling radiation power and/or field strength during a reading operation from a magneto-optical recording medium comprising a storage layer and a read-out layer. An expanded domain leading to a pulse in a reading signal is generated in said read-out layer by copying a mark region from said storage layer to said read-out layer upon heating by said radiation power and by applying an external magnetic field. A pulse pattern in the reading signal is analyzed. The analyzing result is compared with run length characteristics of the data stored in said storage layer. The radiation power and/or the magnetic field strength are controlled on the basis of the comparison result. Thus, much less or no disc capacity has to be reserved for radiation power and/or magnetic field calibration, since the user data can be used for this purpose.

1 . (Cancel)  
   
   
       2 . A method of controlling an external magnetic field applied during a reading operation from a magneto-optical recording medium ( 10 ) comprising a storage layer and a read-out layer, wherein an expanded domain leading to a pulse in a reading signal is generated in said read-out layer by copying a mark region from said storage layer to said read-out layer upon heating by a radiation power when applying said external magnetic field, said method comprising 
 an analyzing step for analyzing a pulse pattern in said reading signal;    a step for comparing the result of said analyzing step with a run length characteristic of the data stored in said storage layer; and    a controlling step for controlling the strength of said external magnetic field on the basis of the comparison result.    
   
   
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       14 . A reading apparatus for controlling an external magnetic field applied during a reading operation from a magneto-optical recording medium ( 10 ) comprising a storage layer and a read-out layer, wherein an expanded domain leading to a pulse in a reading signal is generated in said read-out layer by copying a mark region from said storage layer to said read-out layer upon heating by a radiation power and when applying said external magnetic field, said apparatus comprising: 
 analyzing means ( 21 ) for analyzing a pulse pattern in said reading signal;    comparing means ( 22 ) for comparing the result of said analyzing by said analyzing means ( 21 ) with a run length characteristic of the data stored in said storage layer; and    field control means ( 25 ) for controlling the strength of said external magnetic field on the basis of the comparison result.    
   
   
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       17 . A magneto-optical record carrier comprising a storage layer and a read-out layer, wherein an expanded domain is generated in said read-out layer by copying a mark region from said storage layer to said read-out layer upon heating by a radiation power and when applying an external magnetic field, said record carrier ( 10 ) comprising control information for use in the control of the magnetic field and/or the radiation power during a reading operation.  
   
   
       18 . A record carrier as claimed in  claim 17 , wherein said control information defines a medium-related characteristic between a copy window size and the radiation power.  
   
   
       19 . A magneto-optical record carrier comprising a storage layer and a read-out layer, wherein an expanded domain is generated in said read-out layer by copying a mark region from said storage layer to said read-out layer upon heating by a radiation power and when applying an external magnetic field, said record carrier ( 10 ) comprising a test pattern with a predetermined run-length characteristic for use in the control of the magnetic field and/or the radiation power during a reading operation.  
   
   
       20 . A record carrier as claimed in  claim 17 , wherein said record carrier is a MAMMOS disk ( 10 ).