Appeal No. 1999-2713 Page 11
Application No. 08/801,805
scatter the light L. The examiner and appellants agree that
APA does not disclose a roughened emitter surface.
From the disclosure of Endo of using a 90% to 95%
transmissivity guide element or transparent glass, and
providing a roughened emission surface to scatter light at the
emission surface, we find no reason why a skilled artisan
would have been led to provide the light guide of APA with a
roughened emission surface, because APA uses fine particles in
the light guide to scatter the light. Endo needs the
roughened emission surface to scatter the light because of the
high transmissivity of the light guide. Since the light in
APA is already scattered by the fine particles within the
light guide, there is no need to scatter the light at the
emission surface, where the prism 5 corrects the directivity.
In addition, Endo uses a roughened emission surface to
compensate for non-uniformity of brightness due to the use of
light sources at both ends of the light guide. Because APA
does not have light sources at both ends of the light guide,
we find that an artisan would not have been led to provide a
roughened surface on the emitter surface for the additional
Page: Previous 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Next
Last modified: November 3, 2007