JOHN RANDOLPH BARBER
Pilots at Tower Hl Ave, San Jose, CA

4052750, Oct 4, 1977

Dec 5, 1975

5/637915

John A. Barber - San Jose CA
C. Norman Dion - San Jose CA
Richard N. James - San Jose CA

Dysan Corporation - Santa Clara CA

G11B 582, B65D 8502, G11B 5016, H05F 300

360135

An improved flexible magnetic recording disc assembly comprising an envelope and a flexible recording disc rotatably received in the envelope, the disc having an annular reinforcement member concentrically arranged adjacent the central mounting aperture of the disc. Two embodiments are disclosed: a first having a single annular reinforcement member secured to the spindle side of the flexible disc; and a second having a pair of annular reinforcement members disposed on opposite surfaces of the disc. The reinforcement member has an axial thickness in the range from about 2 to about 7 mils to provide sufficient structural rigidity to resist crinkling and flaring during use; a static and dynamic coefficient of friction not less than about 0. 3, and a total electrical resistance measured in the longitudinal axial direction in the range of about 1 ohm to about 50 megohms to facilitate dissipation of static electrical charges which may build up on the recording surfaces of the disc. The reinforcement member is adhered to the flexible disc by means of a cement which is preferably electrically conductive, also to promote static charge dissipation.