Projection lens unit and rear projection type image display...

Details Projection lens unit and rear projection type image display... Projection lens unit and rear projection type image display...

2007-02-06

2007-02-06

Perkey, W. B. (Department: 2851)

Optics: image projectors

Cabinet encloses projector and one side of screen

Focus or variable magnification

C353S100000, C348S745000, C359S365000

Reexamination Certificate

active

10865549

ABSTRACT:
An inexpensive projection lens unit in a rear projection type image display system, having a short focal distance (wide angle of viewing field), high focus and high contrast, and as well, including a power lens made of a glass material having a high refractive index in a range from 1.63 to 1.70 and an Abbe's number of not less than 50 with an optimized incident and emergent configuration in order to satisfactorily correct aberration with a enhanced focusing performance even with a shortened focal distance. Further, the power lens having a high refractive index can exhibit a high power, and accordingly, can carry out satisfactory aberration correction by optimizing the aspheric degree of a plastic lens even though the length of back focus is increased for enhancing the contrast.

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