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.
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