Abstract: In a data slicer and data slicing method for an optical disc system, the data slicer for converting an analog input signal into a digital signal includes a comparator, a duty detector, and a low pass filter. The comparator compares the analog input signal with a feedback signal to generate the digital signal. The duty detector detects the duty of the digital signal. If the detected duty is longer than a preset duration, the duty detector converts the detected signal into a signal having the preset duration, and outputs the converted signal. The low pass filter integrates the output signal of the duty detector to generate the feedback signal.

Abstract: An optical disc reproducing apparatus including a viterbi detector for an optical disc in which digital data is stored includes an optical pick-up for reading digital data stored in the optical disc and for generating a high frequency signal, an analog-to-digital converter for sampling and quantizing the high frequency signal, and a viterbi detector for decoding a quantized signal output from the analog-to digital converter and reproducing an eight to fourteen modulation (EFM)/EFM+signal. The viterbi detector includes a branch metric calculator for receiving a signal constituted of n bits, for comparing the signal with previously set three variables, and for calculating a branch metric with respect to the input signal. A path metric update and storage unit receives the branch metric, adds the branch metric to values stored therein, compares the error content of all the possible paths with each other, and stores a metric with respect to the path having the smallest amount of errors.

Abstract: In a data slicer and data slicing method for an optical disc system, the data slicer for converting an analog input signal into a digital signal includes a comparator, a duty detector, and a low pass filter. The comparator compares the analog input signal with a feedback signal to generate the digital signal. The duty detector detects the duty of the digital signal. If the detected duty is longer than a preset duration, the duty detector converts the detected signal into a signal having the preset duration, and outputs the converted signal. The low pass filter integrates the output signal of the duty detector to generate the feedback signal.

Abstract: A control apparatus and method for controlling a velocity of a spindle motor included in an optical disk reproducing system to prevent a forward or backward overrun of a spindle motor are disclosed. A widest signal detector of the apparatus detects the widest pulse width of an eight-to-fourteen modulation (EFM) signal according to a main clock signal and generates a first status signal representing a status of the pulse width of the detected signal according to a frame clock signal, which is divided by a first predetermined number j. A narrowest signal detector of the apparatus generates a second status signal representing a status of the narrowest pulse width of the first status signals according to the frame clock signal divided by a second predetermined number k, where k is greater than j. An overrun controller increases or decreases or holds a previously counted result according to the frame clock signal divided by the second predetermined number and the second status signal.

Abstract: A method and apparatus are provided to buffer commands sent from a computer to a peripheral device such as an optical disk data reproduction system, e.g., a CD-ROM drive, so that, even when execution of a command by a microcontroller of the peripheral device is not completed, additional commands from the computer can be queued.

Abstract: Reed-Solomon encoded data read from a CD-ROM, DVD-ROM, or other recording or transmission source is error corrected at high speed in an apparatus that employs a pair of byte-wide error correcting sub-circuits operating substantially in parallel. An MSB plane of a sector of received Reed-Solomon data is processed in one error correcting circuit while an LSB plane of the same sector is processed in the other circuit. Errors are corrected in each sub-circuit as may be necessary, and selection circuitry selects the corrected data, or non-corrected data, as appropriate, for each plane, and then combines the selected data to form the word-wide output data for transmission, e.g. to a host processor. The operation is pipelined and, although only one error is corrected at a time, the invention provides word-wide, error-corrected data at a data rate only a few clock cycles slower than prior art byte serial EC technology, so the effective transmission rate to the host is substantially improved.

Abstract: A spindle servo circuit in an optical disc reproducing apparatus operates with enhanced stability at disc rotation speeds substantially higher than normal. The spindle servo circuit includes a first phase comparator which compares the phases of a reference clock signal and a reproduced frame clock signal and outputs a phase difference signal. The spindle servo circuit also includes a first low pass filter for generating a revolution speed control signal for a spindle motor by low-pass filtering the phase difference signal. The revolution speed control signal is input to a motor driving means for driving revolution of a spindle motor, which in turn spins the optical disc. Optical signals are picked up off the disc and run through a high frequency amplifier for amplifying and wave-shaping to produce a reproduction data signal.