Patent ID: 6388970
Filing Date: 2002-05-14
Classification: G11B

Abstract:
A method for compensating for thermal effects in mark lengths on a compact disk, the method comprising:providing a sequence of alternating mark and space characters formed on a CD-R/RW disk; measuring the lengths of selected consecutive triples of characters of a preceding mark, a preceding space and a present mark, denoted as L(PM), L(PS) and L(MK), respectively; computing a difference &Dgr;m=&Dgr;L(MK)/T between the length L(MK)/T and a reference length L0(MK)T=m0 for each of a selected sequence of combinations of the lengths m0, L(PM)/T=m1 and L(PS)/T=m2, and computing a mean value &mgr;(&Dgr;m;m0;m1;m2) of the difference for each of the sequence of combinations, where T is a selected length value; determining the number p of length measurements L(MK) used to determine the value &mgr;(&Dgr;m;m0;m1;m2) for at least one combination of said lengths m0, m1 and m2; when p is at least equal to a selected positive integer M1, accepting and storing said value &mgr;(&Dgr;m;m0;m1;m2) as an estimate of thermal effects of character writing length for the at least one combination; and when p is less than M1, using a selected algorithm to determine an adjusted value &mgr;â€²(&Dgr;m;m0;m1;m2), and accepting and storing said value &mgr;â€²(&Dgr;m;m0;m1;m2) as an estimate of thermal effects of character writing length for the at least one combination.