Sony Corporation

Motoyasu Yumita

Masayoshi Nagata

Junichi Horigome

A playback apparatus that plays back a recording medium having recording layers includes an optical head irradiating the recording layers with laser light using an objective lens and reading information recorded in the recording layers; an actuator holding the objective lens; focus servo means for driving the actuator to execute focus servo; layer movement driving means for driving the actuator to perform movement of the objective lens in an interlayer direction; tracking servo means for driving the actuator to execute tracking servo; center-point servo means for driving the actuator to execute center-point servo for setting the objective lens to a center point position; and layer jump sequence control means for performing a series of layer jump operations and causing the center-point servo means to execute the center-point servo in a predetermined time within a period during which the series of layer jump operations is performed.

Playback apparatus and layer jump method

In an optical recording medium of a recording format to record data on both lands and grooves in such a manner that a recording area is divided into a plurality of zones, and headers arranged continuously in radial directions in the same zone are not arranged in the same radial directions over a zone boundary, and the headers are so arranged as to be shared by the lands and the grooves, the headers arranged within three or more physical tracks from said zone boundary are cleared and grooved. Thereby, noise is prevented from occurring in a tracking error signal about the time from the occurrence of noise, which occurs in the tracking error signal and causes landing, until a tracking servo is performed, thus making it possible to enhance the stability of landing traversing a zone boundary.

Optical recording medium

A disk recording medium has reliability of address reading which is maintained equivalently to the conventional disk recording medium by recording a first address and a second address that are identical in a header area. By arranging the first and second addresses to be reversely displaced from the center line of a groove track or a land track to the radial direction of the medium, the distance between the first and second addresses when they are adjacent is increased, which eliminates the influence of crosstalk. This avoids redundancy of the header area and enables high-density recording to the disk recording medium.

DISK RECORDING MEDIUM INCLUDING DATA PRE-FORMATTED-DATA-RECORDED HEADER HAVING FIRST AND SECOND IDENTICAL ADDRESS NUMBERS RADIALLY DISPLACED FROM EACH OTHER ON OPPOSITE SIDES OF GROOVE OR LAND TRACK CENTER LINE, AND DISK DRIVE UNIT FOR USE WITH THE RECORDING MEDIUM

A disk apparatus according to the present invention includes a rotating means for rotating a disk, a head for accessing the disk, and a head moving means of moving the head in the radius direction of the disk. The head moving means includes a first voice coil motor as a drive source used when the head is moved, a second voice coil motor as a drive source used when the head is moved, a head guide means for guiding the head in the radius direction of the disk when the head is moved, a drive means for supplying a drive signal to the first voice coil motor during a first period in which the head is moved to a predetermined position on the disk and for supplying the drive signal to the first voice coil motor and the second voice coil motor during a second period in which the head is moved from the predetermined position on the disk to another position thereon, and a counterelectromotive voltage detecting means for detecting a counterelectromotive voltage from the second voice coil motor when the drive signal is not supplied to the second voice coil motor. The drive means drives the first voice coil motor based on an output from the counterelectromotive voltage detecting means so that the head should be moved to the predetermined position on the disk.

Growing community of inventors

Kanagawa, Japan

Motoyasu Yumita