Platte und Plattenklemmvorrichtung

摘要

A recording disc (d) for information signals includes a disc substrate (1) carrying a signal recording section (1a) on at least one of the surfaces, a positioning reference plane (4a) at a central region of one of the surfaces of the disc substrate (1), and an upright wall portion (4) integrally connecting the reference plane (4a) to the signal recording section (1a). A chucking device for chucking the recording disc to a disc rotating unit includes a disc table (103) having a disc setting portion (103a) and integrally mounted on a rotating shaft (102a) of a spindle motor (102), a centring member (104) reciprocably mounted on the disc table (103) and to abut an inner surface of the reference plane (4a) of the recording disc (d) to centre the recording disc, and a magnet (105) mounted at the foremost part of the disc setting unit inwardly of the centring member (104) and to attract a magnetic plate (2) provided on the recording disc (d) set on the disc table (103).