Patent ID: 7643237

Claim:
A media storage device, comprising: a head which reads and writes data from and to a storage medium; a channel circuit which measures signal quality of read data and demodulates the read data from said head and modulates write data for said head; a control circuit which controls read and write operations of said head according to commands from a higher-level device; and a management table which holds management information, having, in write command units, storage area information for write data specified by said write command and signal quality information to detect thermal relaxation of said write data, wherein said control circuit, at the time of reception of said write command from said higher-level device, creates said management information for the write data of said received write command in said table, and judges whether time information indicating the time elapsed from the recording time of said recorded data has exceeded a thermal relaxation reference time in units of said write data, and wherein said control circuit, when said time information exceeds said thermal relaxation reference time, reads, via said channel circuit, data recorded on said storage medium in units of storage areas in said management table, measures said signal quality detected by said channel circuit during said reading in said write command units, and performs updates of said signal quality information in said management table using said measured values, while also judging the degradation of data in said write command units comparing said measured value with a prescribed threshold value, and depending on the result of said comparison, re-recording data in said write command units on said storage medium.