ON THE RECORDING CODE WHICH IMPROVES THE GROOVE PARAMETER

Abstract

In order to increase the recording capacity the mark edge recording and (1, 7)RLL code are employed in the second generation ISO/IEC optical disk standard. However this recording method degrades groove parameter at ROM area because (1, 7)RLL code has long Tmax which causes recording pattern of combination of long pits and short spaces. New (2, 5)RLL code whose Tmax is small were developed. Because Tmax/Tmin gets close to unity, the information capacity of the code is small so that detection window width becomes narrow. Because narrow band signal to noise ratio is large and jitter is small in ROM area, the window margin of (2, 5)RLL code written in ROM area is same as that of (1, 7)RLL code written in MO area when both codes are recorded in the same recording density. The window width of (2, 5)RLL code is 0.4Tb and Tmin is 1.2Tb where Tb is one bit length of information bit.