Appeal No. 1999-2713 Page 10
Application No. 08/801,805
guiding material and the diffusion plate. Endo further
discloses (col. 5, line 63-col. 6, line 14, and col. 2, lines
57 and 58) that since the light is concentrated from both ends
of the substrate to the area near the center of the light
guiding element, the brightness becomes comparatively high at
the center and sometimes results in a problem. In order to
overcome the problem of non-uniformity of brightness, "[t]he
surface of the light guiding element is formed as a rough
surface in order to scatter the light at this surface." When
the degree of roughness is small, less light is scattered.
The light guiding element does not have the same roughness
across its entire surface. The area near the center is formed
with a degree of roughness set to a small value. The
remaining surface is formed as a rough surface. As a result,
the light is emitted "toward a region other than the center
area, resulting in the brightness in the center being
suppressed and a more uniform brightness can be obtained."
In APA (specification, page 3), the light guide 2 is a
light scattering guide plate containing uniformly distributed
light-permeable fine particles. The light-permeable fine
particles distributed in the light scattering guide plate 2
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Last modified: November 3, 2007