This invention relates to apparatus for clamping and centering a flexible magnetic recording disc in a disc drive.
Disc drive units incorporating inexpensive, flexible, removable magnetic recording discs have become very popular in the field of data processing. These drives and their associated discs provide for a relatively inexpensive means for storing data, diagnostic codes, or programs for computers and other types of equipment. Because of the low cost recording media used therein and its replaceability, these devices have provided for an inexpensive means of providing such stored information in a wide variety of equipment. A number of manufacturers are now producing generally similar disc drives of this nature, with one relatively new and increasingly popular such drive being the Memorex Model 550, within which the subject matter of the present invention may be incorporated. The recording media generally used in such disc drives is in the form of a relatively thin and flexible plastic disc coated with a magnetic recording material and enclosed within an envelope providing for limited access to the recording surface of the disc and access to a central, circular aperture which is used for centering and clamping the disc to the disc drive.
Various types of disc centering and clamping structures have been incorporated and disclosed in the prior art. Typical of such clamping apparatus has been that disclosed in U.S. Pat. No. 3,678,481 and that disclosed in U.S. Pat. No. 3,768,815. Among the requirements for such a disc centering and clamping structure have been the ability to effectively and positively center the disc with respect to the axis of rotation of the drive spindle prior to clamping it immovably in place on that spindle, reliability of operation, and simplicity and low cost of manufacture and assembly. The various prior art clamping devices have, in general, been unnecessarily complex and frequently lacking in the ability to center a disc effectively prior to clamping it firmly against the drive spindle. This failure to center properly can result in damage to the material surrounding the central aperture of the disc as well as an eccentric recording and substantial compromises in the ability of the disc and drive combination to reproduce accurately data previously recorded thereupon. The inability of many of the prior are devices to center the disc adequately prior to clamping has become a particularly acute problem with respect to the more recently developed disc drives in which the recording density has been substantially increased and the distance between adjacent recording tracks has been substantially decreased.