Mitsubishi Chemical Corporation

Diafoil Hoechst Company, Limited

Mitsubishi Kasei Corporation

Hidemi Yoshida

Kenichi Uchino

Chiga Ueda

Shuichi Maeda

Masaaki Mizuno

Yutaka Kurose

Kenji Kato

Hideharu Takeshima

Michiyo Kimura

Toshio Kaneko

Shizue Inaba

A magneto-optical disk has a recording film on a substrate for defining a data area. The data area is divided into a plurality of zones in the radial direction, and each zone has a plurality of physical tracks divided into a plurality of sectors along the tracks. Number of sectors per physical track in each zone is increased as viewed toward the outer edge of the disk one by one. The shortest mark length in specified zones in the vicinity of the inner and outer edges of the disk is longer than that in other zones to thereby improve reliability in recording/reproducing characteristics in the specified zones, which have otherwise degraded recording/reproducing characteristics due to inferior physical characteristics of the recording film.

Optical disk having a large storage capacity

An optical tape comprising a substrate having a center line average roughness (Ra.sup.A) on one side of 0.005 to 0.5 .mu.m and a tensile strength (F.sub.5) in the longitudinal direction of not less than 8 kg/mm.sup.2, and an optical recording layer formed on the other side of said substrate.

Optical tape

Disclosed herein are an optical recording method of conducting recording/reading out for information by irradiating a laser beam at a wavelength of not more than 500 nm onto a recording layer of an optical disc having a track pitch of not less than 0.4 .mu.m and less than 0.9 .mu.m, the laser beam being incident from a disc substrate side of the optical disc using an objective lens having numerical aperture of 0.55 to 0.70, a recording area for information recording on the disc substrate being a flat area not having a guide groove for each track, and the disc substrate having a in-plane birefringence of not more than 20.times.10.sup.-6 and a vertical birefringence of not more than 300.times.10.sup.-6, and an optical recording medium suitable for use in the optical recording method.

High density optical recording method and recording medium

Disclosed herein is an optical tape comprising: a substrate whose a center-line average roughness (Ra.sup.B) on the surface of one side is not more than 0.005 .mu.m and the number of coarse protuberances having a height of not less than 0.10 .mu.m in the surface of that side is not more than 10 protuberances/cm.sup.2, and an optical recording layer formed on the surface whose the Ra.sup.B is not more than 0.005 .mu.m.

A metal-containing indoaniline compound having the formula: ##STR1## wherein M is a metal atom of Group VIII, Ib, IIb, IIIb, IVa, Va, VIa or VIIa of the Periodic Table or its halide or oxide, rings A, B, C, D, E and F may have substituents, each of K.sup.1 K.sup.2 and K.sup.3 is a residue of a substituted or unsubstituted aromatic amine, each of l, m and n is 0 or 1, provided l+m+n=2 or 3, and p is 2, 3 or 4.

Growing community of inventors

Atsugi, Japan

Hidemi Yoshida