Pioneer Electronic Corporation

Pioneer Video Corporation

Other

Satoru Fukuoka

Kenji Suzuki

Toshihiko Takishita

Minemasa Ohta

Nobuki Yamaoka

Hiroyuki Kosaka

Tsuyoshi Hayashi

Tuyoshi Hayashi

Hirokazu Hashikawa

Yukihiro Sugawara

An optical disc comprises; a substrate; grooves concentrically or helically formed on the substrate in each of which data is recorded; lands defined between the adjacent grooves; and prepits formed on the lands, wherein each of the prepits is disposed to be shifted from a center line of the land toward a groove to be paired without overlapping with adjacent tracks, whereby reducing cross-talk from adjacent tracks and improving the density of recorded data.

Optical disc

An optical disc includes two transparent substrate layers each having a recording surface with a plurality of pits arranged concentrically or spirally. The plurality of pits represents information stored on the recording surface. Each transparent substrate layer has a thickness of 0.6.+-.0.03 mm. A reflecting layer is formed on each of the recording surfaces of the two transparent substrate layers. An inclining angle formed between a pit inner wall and a normal line of each transparent substrate layer is 20.degree.-55.degree., and pit depth is set to be .lambda./3.5N-.lambda./2.7N. .lambda. is defined as the wavelength of a laser beam incident the optical disc for reading the information recorded on the optical disc, and N is the index of refraction of each transparent substrate layer.

High density optical disc configuration

A photo-resist layer of positive type, which is formed by a predetermined thickness on a disc substrate and which is exposed by a light beam modulated in accordance with record information to produce an optical record medium comprising the photo-resist layer and the disc substrate, is developed by the developing method. The developing method includes the steps of: firstly developing the exposed photo-resist layer by alkaline developing solution which has a normality of 0.17 to 0.19N for a first time period such that the photo-resist layer be incompletely developed to a predetermined depth from a surface of the exposed photo-resist layer; firstly washing the firstly developed photo-resist layer to stop the firstly developing step, and firstly drying the firstly washed photo-resist layer; secondly developing the firstly dried photo-resist layer by the alkaline developing solution for a second time period which is longer than the first time period such that the photo-resist layer be completely developed to a pit depth; and secondly washing the secondly developed photo-resist layer to stop the secondly developing step, and drying the secondly washed photo-resist layer to produce the optical record medium recorded with the record information as a developed pit pattern.

Developing method and developing apparatus for optical record medium

An optical disk of the type including guide grooves is improved by regulating the width of the grooves, and thus the width of the adjacent land portion, in accordance with the type of information recorded at that part of the land.

Optical disk having narrow and wide guide grooves

In an optical disk manufacturing method in which a first photo resist layer, an intermediate resin layer, and a second photo resist layer are formed on a substrate in the stated order, a resin solution which is unsoluble in organic solvent is applied to the first photo resist layer, heated, and hardened to form the intermediate resin layer. Thereby the use of a large, expensive device such as a vacuum deposition device or sputting device is eliminated.

Growing community of inventors

Yamanashi, Japan

Satoru Fukuoka