Pioneer Electronic Corporation

Manabu Sugano

Fumio Matsui

Naoharu Yanagawa

Hiroshi Suzuki

Susumu Nomura

A pickup apparatus of an optical card has an improved data transfer efficiency and miniaturization and thin shape of the apparatus can be realized. The length of a line segment connecting a center of an objective lens provided in a rotational optical unit and a center of a rotary drum is set to a length specified by a length in the major side direction on a recording surface of the optical card and (1+cos.theta./2). An optical pickup apparatus has: a fixed optical unit SOP; a rotary drum in reflecting mirrors for guiding a light beam B emitted from the fixed optical unit SOP to a recording surface of an optical card and an objective lens are mounted; and a rotational optical unit ROP having a rotary motor for rotating the rotary drum, wherein information is recorded and reproduced to and from the recording surface of the optical card. A length of a line segment connecting the center of the objective lens and the center of rotation of the rotary drum is decided on the basis of a length in the major side direction on the recording surface of the optical card and (1+cos.theta./2).

Rotational optical head for optical recording medium

An information recording disc comprising a generally circular substrate having a polished major surface, a light-reflective coating formed on the polished major surface of the substrate, and a light-absorptive coating formed on the surface of the light-reflective coating and formed with information tracks each consisting of a succession of spaced pits in the light-absorptive coating, the light-absorptive coating being composed of a mixture of cellulose nitrate and a dye sensitizer exhibiting a noticeable light absorptivity in response to light with a predetermined wavelength, the cellulose nitrate being prepared from a starting cellulose containing at least about 97% of alpha-cellulose. If desired, the light-reflective coating may be dispensed with so that the light-absorptive information recording coating is formed directly on the polished surface of the substrate.

Growing community of inventors

Tokorozawa, Japan

Manabu Sugano