Optical data system and high density optical disk relating thereto

Abstract

An apparatus for recording data includes a source of digital data arranged into data words having a given number of bits and a converter that converts the data words to code words having one more bit than the given number using a group code recording format. The code words include a binary signal having first and second binary values at a given clock interval determined by a bit rate of the code words. The apparatus also includes a storage disk having a recording surface, a drive member for rotatably driving the disk, a laser having a focused beam, and a control assembly for directing the laser at the recording surface so that the beam accesses one of a plurality of concentric tracks on the recording surface. A circuit assembly provides a driving signal utilized for generating energizing pulses having a duration less than the clock interval when the binary signal has the first binary value. A pulse generator applies the energizing pulses to the laser to activate the laser responsive to the energizing pulses so that the laser is turned on and off even when the binary signal does not change value from one bit to the next. A high density optical disk including a plurality of tracks arranged in a predetermined number of zones may be utilized in conjunction the apparatus, which may be further incorporated into an optical data storage and retrieval system.