Focus corrector for zoom projection lenses used with pixelized panels
AssigneeU.S. Precision Lens Incorporated
InventorMelvyn H. Kreitzer
Life of this patent
Estimating the term…
Abstract
A zoom projection lens for use with pixelized panels is provided. The projection lens has a negative/positive (retrofocus) form, with the positive lens unit (U2) having two positive subunits (U2S1, U2S2). The image (screen) side subunit (U2S1) serves as focus corrector for the lens, i.e., after zooming, this subunit is moved to adjust the focus of the lens. Compared to moving the negative unit (U1), this approach achieves better aberration correction and involves moving less mass through smaller distances.
Claims10
A zoom 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 lens unit having a negative power;
- (B) a second lens unit having a positive power, said second lens unit being separated from the first lens unit by a first axial space which is varied during zooming;
- (C) an aperture stop located between the first lens unit and the second lens unit;
- and
- (D) an optional field lens unit;
- wherein:
- (i) the second lens unit consists in order from its image end to its object end of:
- (a) a first lens subunit having a positive power;
- and
- (b) a second lens subunit having a positive power, said second lens subunit being separated from the first lens subunit by a second axial space;
- and
- (ii) during focusing, the first lens subunit is moved to vary the second axial space.
Dependencies are inferred from the claim text.