Patent ID: 6243352
Filing Date: 2001-06-05
Classification: G11B

Abstract:
An optical disc having a double spiral structure defined by alternating straight and wobbled grooves and data recorded with a density pb of less than or equal to 0.326 .mu.m.sup.2, where p is track pitch and b is bit length, wherein,p is at least 0.90 .mu.m but not more than 1.00 .mu.m,b is at least 0.326 .mu.m but not more than 0.363 .mu.m,a perpendicular double refraction index of the disc is not greater than 300.times.10.sup.-6,a land duty of the disk is 61 to 69%,jitter produced when random pattern signals are recorded on one track only is not more than 8.4% andjitter increase on recording of signals also on both sides of neighboring tracks is not more than 4.9%.