Sony Corporation

Hiroaki Mizuma

Kenji Yamamoto

Noriaki Nishi

Motoi Kimura

Masatoshi Nishino

Naoki Inoue

Mitsuyoshi Kawaguchi

Takuji Nakamura

The light intensity of a light beam emitted from a light source is appropriately controlled when the light beam is transmitted through a variable optical coupling efficiency device in an optical head. During a read mode, the light beam from the light source is incident on an optical disk at an intensity relatively weaker than that of the light source. By switching the optical coupling efficiency of the variable optical coupling efficiency device between a write mode and a read mode, the light intensity directed to an optical recording medium is substantially varied from the write mode to the read mode. This arrangement eliminates the need for substantially increasing the optical output power ratio of the light source of write power to read power.

Recording and playback apparatus and optical head

A disc drive unit capable of simply performing an opening and closing driving of shutters by rotation of an inner rotor of a disc cartridge using the inner rotor is provided. A disc drive unit is constituted so as to open and close shutters () by rotationally driving a partial gear () of the inner rotor () by a rack portion () of a rack member () slidably driving it relative to a disc cartridge ().

Disk-drive device

Recording and playback apparatus and optical head including a variable optical coupling efficiency device

Growing community of inventors

Tokyo, Japan

Hiroaki Mizuma