Disk recording device

Abstract

For an overwriting operation, recorded data is read from a disk, and a bit clock is reproduced from the read, recorded data in a clock reproduction circuit ( 7 ). Data processing in an encoder ( 14 ) is performed in synchronism with the reproduced bit clock. With the above, recording data is output from the encoder ( 14 ) in synchronism with the recorded data in the disk whereby recording data to write onto the disk for overwriting is synchronized with the recorded data. A defined recording region is thus precisely overwritten.

What is claimed is:  
     
         1 . A disk recording device capable of data writing onto a disk for overwriting, comprising: 
 a clock reproduction circuit for reproducing a bit clock from recorded data read from the disk;    an encoder for data processing to modulate input data into recording data suitable for recording onto the disk; and    an optical head for reading recorded data from the disk, and for writing the recording data supplied from the encoder;    wherein, for an overwriting operation, 
 the optical head reads the recorded data from the disk,  
 the clock reproduction circuits reproduces a bit clock from the recorded data read by the optical head,  
 the encoder performs data processing in synchronism with the bit clock reproduced by the clock reproduction circuit to thereby prepare recording data which is in synchronism with the recorded data, and  
 the optical head writes the recording data onto the disk based on an output from the encoder.  
   
     
     
         2 . A device according to  claim 1 , further comprising an interface for receiving an overwrite request which contains a designation of a recording region to be overwritten with the recording data, and a recording start position detector for detecting a recording start position on the disk based on the designation of a recording region, which is contained in the overwrite request received by the interface, wherein recording of an output from the encoder which is in synchronism with the bit clock reproduced by the clock reproduction circuit is begun at the recording start position detected by the recording start position detector.  
     
     
         3 . A device according to  claim 1 , wherein the optical head generates a main beam for recording onto the disk, and a preceding beam for tracing a signal track on the disk prior to the main beam, and detects a reflection beam of the preceding beam, reflected from the disk, and the clock reproduction circuit reproduces the bit clock based on a result of detection of the reflection beam of the preceding beam.  
     
     
         4 . A device according to  claim 3 , wherein the optical head includes a first light source for generating the main beam and a second light source which is different from the first light source, for generating the preceding beam.  
     
     
         5 . A device according to  claim 4 , wherein an output from the second light source is controlled independently of an output from the first light source.  
     
     
         6 . A device according to  claim 3 , wherein the optical head generates a following beam for tracing the signal track on the disk subsequently to the main beam to detect a reflection beam of the following beam, reflected from the disk, and the disk recording device includes a verifying circuit for verifying data recorded on the disk by comparing a result of detection of the reflection beam of the following beam and the recording data recorded onto the disk by the main beam.  
     
     
         7 . A device according to  claim 6 , wherein the optical head includes a first light source and a second light source which is different from the first light source, wherein the main beam is emitted from the first light source, and the preceding beam and the following beam are formed by splitting a beam emitted by the second light source.  
     
     
         8 . A device according to  claim 1 , wherein the optical head generates a main beam for writing the recording data onto the disk, and receives a reflection of the main beam, reflected from the disk, and the clock reproduction circuit subtracts a varying amount of an output of the main beam from a detection of the reflection of the main beam, reflected from the disk, and reproduces a bit clock based on a difference obtained by this subtraction.