Appeal No. 1998-3355 Application No. 08/665,167 Eaton states that: [f]riction is also reduced by proper lateral contouring of guide 10. It has been shown that enough air leaks from beneath the sides of a tape flying over a simple cylindrical post to produce a lateral tape contour such that the edges of the tape sag or curl. See, for example, Deckert et al, Dynamic Response of Self-acting Foil Bearings, IBM Journal of Research and Development, November, 1974, pp. 513-520, hereby incorporated by reference. Such sagging of the tape edges tends to increase the area of contact between the tape and the guide, thereby increasing friction. By designing the lateral contour of the tape engaging surface to match the lateral profile of the tape, such friction is minimized. Referring to FIGS. 2a and 2b, a front or rear view of guide 10 (from the left side or right side respectively of FIG. 1) reveals the lateral profile of tape engaging surface 11. Tape 1 is shown only as it flies above guide 10, the portion of tape 1 which contacts the tape engaging surface or wraps about the portion of tape engaging surface having radius of curvature 12 is eliminated for convenience. Tape engaging surface 11 has a convex lateral contour which matches the lateral profile of tape 1. In FIG. 2a, the convex lateral contour is crowned, in FIG. 2b the width of guide 10 is reduced and the convex lateral contour is created by edge rounding. Suitable crowned guides have been manufactured with lateral radii of curvature of 300 mm to infinity for a tape approximately 8.0 mm wide and 12 microns thick. The optimum lateral contour for an application will vary depending upon the stiffness of the tape, longitudinal contour of the guide, and operating parameters of the application. (See Eaton at column 4, line 51- column 5, line 14.) While Eaton does disclose that friction may be reduced by the lateral contour and that the optimum lateral contour will vary between applications and operating conditions, Eaton provides no motivation or line of reasoning for selecting the specific range of dimensions as recited in claim 13. 5Page: Previous 1 2 3 4 5 6 7 8 NextLast modified: November 3, 2007