A tray unit is slidably attached to a frame. The tray unit comprises a disc tray which slides with respect to the frame, and a pickup unit supported by a damper to the disc tray. The pickup unit includes a shutter for closing an opening through which an optical pickup is exposed when the disc tray is drawn out of the frame. The shutter is opened or closed according to a condition of contact between a tip of a shutter opening/closing lever projecting from a side wall of the disc tray and a cam fixed on the frame.
An optical disk apparatus for detecting synchronization signals of an optical disk. Marks and spaces are alternately arranged as synchronization signals of the optical disk. An encoding/decoding circuit of the optical disk apparatus utilizes a rule for alternately arranging synchronization signals, thereby verifying a detected synchronization signal. When the polarity of a synchronization signal detected from a preceding synchronization frame is a mark, the next synchronization signal is a space. When the polarity of a detected synchronization signal is a space, the signal is determined to be a correct synchronization signal.
An optical disk drive which increases a read rate when a read command from a host system is input. Data read from the optical disk drive are buffered in cache memory, and requested data are subsequently transferred to a host system. The cache memory is divided into cache A and cache B. Directory data are chiefly buffered in the cache A, and file data are chiefly buffered in the cache B. A cache hit rate achieved when the directory data and the file data are alternately read is improved.
In an optical disk of HD-DVD, data is recorded in both grooves and lands. A groove track includes its own data region called a groove (G) track address system formed therein and a land track includes its own data region called a land (L) track address system formed therein. When tracing a groove track, address information X is read from the G track address system, and also address information Y is read from the L track address system. If neither relationship X=Y or X=Y+1 is satisfied, it is determined that the address information X includes an error. Further, a groove track includes its own data region called a groove (G) track address system having a parity bit formed therein and a land track includes its own data region called a land (L) track address system having a parity bit formed therein. When tracing a groove track, address information X is read from the G track address system, and also address information Y is read from the L track address system. Even when the parity is correct, if neither relationship X=Y or X=Y+1 is satisfied, it is determined that the address information X includes an error.
A high-definition optical disk device for recording and reproducing data with respect to lands and grooves of an optical disk. The grooves and the lands of the optical disk are wobbled, and address information is embedded in gray code. In the grooves and the lands, both groove track address systems and land track address systems are embedded and form redundant systems. When detecting the address of a land, in addition to demodulation of the address data from the land track address system, the address data is also extracted from the groove track address system. The address data thus extracted is used for verification to detect an error in the demodulated address data.