Athermal LCD projection lens
AssigneeU.S. Precision Lens Incorporated
InventorMelvyn H. Kreitzer
Life of this patent
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Abstract
A four element, athermalized projection lens for use in forming an enlarged color image of a LCD panel is disclosed. The powers of the elements from the screen to the LCD are negative/positive/negative/positive and the dispersions are low dispersion/low dispersion/high dispersion/low dispersion. The first three elements are composed of plastic and the last element is composed of glass. The projection lens exhibits a high level of aberration correction over magnifications ranging from about 5.times. to about 12.times.. The four element design comprises the minimum number of elements capable of achieving a relatively long back focal length, athermalization, and lateral color correction of less than about half a pixel.
Claims16
A projection lens for forming an image of an object, said lens consisting in order from its image end to its object end of:
- (a) a first low dispersion, plastic lens element having a negative power and a V-value V.sub.1 ;
- (b) a second low dispersion, plastic lens element having a positive power and a V-value V.sub.2 ;
- (c) a third high dispersion, plastic lens element having a negative power and a V-value V.sub.3 ;
- and
- (d) a fourth low dispersion lens element having a V-value V.sub.4 ;
- wherein V.sub.3 is less than each of V.sub.1, V.sub.2, and V.sub.4.
A projection lens for forming an image of an object, said lens comprising in order from its image end to its object end:
- (a) a first low dispersion, plastic lens element having a negative power and a V-value V.sub.1 ;
- (b) a second low dispersion, plastic lens element having a positive power and a V-value V.sub.2 ;
- (c) a third high dispersion, plastic lens element having a negative power and a V-value V.sub.3 ;
- and
- (d) a fourth low dispersion lens element having a V-value V.sub.4 ;
- wherein the magnitude of the power of the second lens element is greater than the magnitude of the power of each of the first, third, and fourth lens elements and wherein V.sub.3 is less than each of V.sub.1, V.sub.2, and V.sub.4.
Dependencies are inferred from the claim text.