Zoom projection lens having a lens correction unit
AssigneeU.S. Precision Lens Incorporated
InventorJacob Moskovich
Life of this patent
Estimating the term…
Abstract
A zoom projection lens for use with LCD or DMD panels is provided. The lens has two units U1 and U2, which are moved relative to one another for zooming. It also has a corrector unit (CR) at a fixed distance from the LCD or DMD panel (PP). The corrector unit, which may be a color correcting doublet, is at the object (panel) end of the lens and has a weak power. This unit allows for a high level of distortion and lateral color correction, without unduly increasing the complexity or cost of the lens.
Claims15
A projection lens for forming an image of an object, said lens having a zoom range between a minimum effective focal length fmin and a maximum effective focal length fmax, said lens comprising in order from its image end to its object end:
- (A) a first lens unit;
- (B) a second lens unit separated from the first lens unit by an axial space, said first and second lens units being moved relative to the object during zooming and/or focusing of the lens;
- and
- (C) a corrector lens unit having at least one aspherical surface and a focal length fCR which satisfies the relationship:
- |fCR/fmin|≧5;
- said corrector lens unit (i) constituting the object end of the projection lens and (ii) being separated from the object by a fixed axial distance DCR-OB and from the second lens unit by a variable axial distance DCR-U2 where:
- DCR-OB≧DCR-U2
- for all effective focal lengths of the lens between fmin and fmax.
A projection lens system for forming an image of an object, said system comprising:
- (A) an illumination system comprising a light source and illumination optics which forms an image of the light source;
- (B) a pixelized panel which comprises the object;
- and
- (C) a projection lens for forming an image of the object, said lens having a zoom range between a minimum effective focal length fmin and a maximum effective focal length fmax, said lens comprising in order from its image end to its object end:
- (a) a first lens unit;
- (b) a second lens unit separated from the first lens unit by an axial space, said first and second lens units being moved relative to the object during zooming and/or focusing of the lens;
- and
- (c) a corrector lens unit having at least one aspherical surface and a focal length fCR which satisfies the relationship:
- |fCR/fmin|≧5;
- said corrector lens unit being separated from the object by a fixed axial distance DCR-OB and from the second lens unit by a variable axial distance DCR-U2 where:
- DCR-OB≧DCR-U2
- for all effective focal lengths of the lens between fmin and fmax.
Dependencies are inferred from the claim text.