Image magnifying Fresnel lens for observation of a on display screen
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United States of America Patent
Stats
-
Jun 5, 2001
Grant Date -
N/A
app pub date -
Sep 24, 1999
filing date -
Oct 12, 1998
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
There is disclosed a Fresnel lens, adapted to be placed in front of a display screen of a computer or a television set in order to magnify images for observation, which does not cause a rainbow-like pattern to appear even when annular prism elements as the constituent elements of said Fresnel lens are arranged at a fine pitch. A spherical surface having a radius of curvature corresponding to the focal distance of the lens formed by said annular prism elements of said Fresnel lens is formed within a circular area defined by a predetermined radius around the optical axis, where the rainbow-like pattern would otherwise appear due to diffraction. The predetermined pitch in arranging a plurality of annular prism elements of the Fresnel lens is equal to or less than 0.25 mm and the height of the annular prism elements in the circular area is equal to or less than 5 .mu.m and preferably equal to or less than 7 .mu.m.
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