Patent ID: 7336440

Claim:
A magnetic disc unit comprising a rotating disc type magnetic disc having an outer periphery, and a carriage arm linked to a head support mechanism supporting a head for recording and reproducing data to and from the magnetic disc, a base having an outer periphery and mounting thereon the rotating disc type magnetic disc and the carriage arm, and a side wall having, on the magnetic disc side, an inner wall surface, formed therein with an opening for inserting the carriage arm, and integrally incorporated with the outer periphery of the magnetic disc over its entirety, for surrounding the magnetic disc and the carriage arm, wherein the inner wall surface of the side wall defines a shroud surrounding the outer periphery of the magnetic disc, except at the opening in the side wall where the shroud is projected inwardly so as to decrease an opening angle of the opening in the side wall, and a gap between the outer periphery of the magnetic disc and the shroud is set in a range not less than 0.1 mm but not greater than 0.6 mm.