Disc holder for optical recording system - has raised, ring-shaped support surfaces on disc carrier mounted on shaft and pressure disc

摘要

The disc holder is esp. for use with a laser recording or reproducing system in which the disc must be held at a constant distance from the laser source to ensure a small spot size. The recording disc (1) is supported on raised ring-shaped surfaces (21, 22) on a disc carrier (2) which is mounted on a shaft (3). The raised surfaces may be near the periphery and the centre of the carrier. The recording disc is held, undistorted, against the raised surfaces by elastic 'O'-rings (51, 52) under a pressure disc (4). The position of the latter can be adjusted to accommodate recording discs of different thicknesses and a constant pressure is maintained by a coil spring (9) and friction disc (8) arrangement.