Abstract: A method and device for controlling a rotation speed of a spindle of an optical disk drive includes a frequency detector, two phase detectors, a frequency divider, a low pass filter, a switch circuit, and a drive circuit. The method uses a wobble signal, an encoder EFM frame synchronization (EEFS) signal, an encoder subcode frame synchronization (ESFS) signal, and other related signals to generate five control signals for controlling the rotation speed of a motor connected to the spindle of the optical disk drive. Using the five control signals, the method limits the phase difference between the Absolute Time in Pre-groove (ATIP) sync and the ESFS to be within a predetermined value, and thus improves an update rate and a writing efficiency.

Abstract: A method and system for optimizing performance of a read buffer and a write buffer in a disc media having a feature requiring apparently simultaneous reading and writing. The method includes alternately writing data to the disc media from the write buffer during a write time tW and reading data from the disc media to the read buffer during a read time tR. The read time and the write time are generally separated by a jump time tJ. The write time is selectively controlled so that it is optimized in accordance with respect to the front end read speed, the decoding bit rate, the front end write speed of the recordable media device and the encoding bit rate.

Abstract: The stable reproduction of wobble signal without generating beats despite of an improvement in recording density by narrowing a track pitch is realized. Data by magnetooptical recording is recorded on wobbling grooves and lands between adjacent wobbling grooves. The wobbling grooves are provided to wobble both sides of the grooves in different amplitudes. Further, both the sides wobbled in different amplitudes are wobbled in phase in the track direction. These different amplitudes of both sides are preferably set to 3.3 to 40%.

Abstract: A calibration for a tracking error signal offset in a tracking servo system of an optical disk drive is presented. In some embodiments, the tracking error signal offset is adjusted for best servo function by, for example, adjusting the center of a tracking error signal when the tracking servo system is open to zero. In some embodiments, the tracking error signal offset is adjusted for best read function by, for example, adjusting the tracking error signal offset until the data jitter is minimized. Data jitter can be determined by reading data from the optical media and measuring the data error rate.

Abstract: A method and related circuit for synchronizing a writing clock with a wobble clock of a compact disk (CD) drive. The CD drive is capable of rotating a CD that has a data track for recording data and a wobble track. The CD drive is capable of generating the wobble clock according to movement of the wobble track while the CD is rotating. Also the CD drive is capable of writing data on the data track according to the writing clock. The method includes adjusting the frequency of the writing clock so as to synchronize the writing clock and the wobble clock.

Abstract: A radio frequency ripple zero crossing signal calibration method for an optical disk reader undergoing a track following to track seeking transition is disclosed. The method utilizes sampling to obtain radio frequency ripple peak level during a track seeking operation and radio frequency ripple DC level during a track following operation and using their differences as a calibrated value. Through the calibrated value, the radio frequency ripple zero crossing slice level is modified so that a correct radio frequency ripple zero crossing signal is obtained during a track following to track seeking transition. In a track following to seeking transition, this arrangement prevents distortion of the radio frequency ripple signal and corresponding drift in the radio frequency zero crossing signal that may lead to errors in computing moving speed and counting tracks of the pickup head. Hence, search capacity of the optical disk reader is improved and the pickup head is better controlled.

Abstract: A method for extracting information in a data signal stored on an optical disc. The information is stored in a plurality of channel bits. The method includes initializing a recovery period of a recovery clock to a predetermined value expressed in cycles of a first clock; sampling the data signal with the first clock; obtaining a leading edge time period expressed in cycles of the first clock of a pattern of bits from the sampled data in which at least a first bit has a first binary value, followed by a plurality of bits having a second binary value, and ending with a last bit having the first binary value, wherein the first and second binary values are not equal; updating the recovery period of the recovery clock to be equal to a new maximum period that is the leading edge time period divided by a division factor; extracting the information in the data signal based on the newest recovery period of the recovery clock; and detecting a predetermined code in the data signal.