WIDE-ANGLE PROJECTION OPTICAL SYSTEM

• US 20100315725A1
• Filed: 06/10/2010
• Published: 12/16/2010
• Est. Priority Date: 06/16/2009
• Status: Active Grant

• Current Assignee: Delta Electronics Incorporated
• Original Assignee: Delta Electronics Incorporated
• Inventors: Lin, Lai-Chang
• Granted Patent: US 8,279,527 B2
• Time in Patent Office: Days
• US Class Current: 359/728
• CPC Class Codes: G02B 13/06 Panoramic objectives; So-called "sky lenses" including panoramic objectives having reflecting surfaces
• CPC Class Codes: G02B 13/16 for use in conjunction with image converters or intensifiers , or for use with projectors, e.g. objectives for projection TV
• CPC Class Codes: G02B 17/08 Catadioptric systems used in non-imaging applications G02B19/00

Abstract

A wide-angle projection optical system includes a first lens set with positive power, an aperture stop, a second lens set with positive power, a third lens set with negative power, and a negative power reflecting mirror. The first lens set provides optical characteristics to match with a light beam coming from the object side. The second lens set is arranged behind the aperture stop to converge the light beam. The third lens set is configured to diverge the light to enlarge a full field angle. The negative power reflecting mirror is configured to further enlarge the full field angle and correct image distortion. The first lens set, the second lens set, the third lens set and the reflecting mirror have a common optical axis. The optical axis is shifted with respect to a center of a micro display.

Claims

1. A wide-angle projection optical system, from an object side to an image side, said wide-angle projection optical system comprising:

a first lens set having positive power, and configured to provide optical characteristics to match with a light beam coming from said object side;

an aperture stop;

a second lens set having positive power, arranged behind said aperture stop, and configured to converge said light beam;

a third lens set with negative power, and configured to diverge said light to enlarge a full field angle; and

a negative power reflecting mirror closer to said image side than said first lens set, said second lens set and said third lens set, and configured to further enlarge said full field angle and correct image distortion,

wherein said first lens set, said second lens set, said third lens set and said reflecting mirror have a common optical axis, and said optical axis is shifted with respect to a center of a micro display.

2. The wide-angle projection optical system according to claim 1 wherein said first lens set, said second lens set and said third lens set are arranged sequentially from said object side to said image side.

3. The wide-angle projection optical system according to claim 1 wherein said third lens set comprises at least three convex-concave lenses, wherein said three convex-concave lenses closest to said image side have meniscus-shaped convex surfaces relative to said image side.

4. The wide-angle projection optical system according to claim 3 wherein both surfaces of each of at least two lenses of said third lens set are aspheric.

5. The wide-angle projection optical system according to claim 3 wherein at least two lenses of said third lens set are manufactured by a plastic molding process.

6. The wide-angle projection optical system according to claim 3 wherein from said object side to said image side, said third lens set comprises a first convex-concave lens, a second convex-concave lens and a third convex-concave lens, wherein said first convex-concave lens is either a regular spherical lens or an aspheric lens, both surfaces of said second convex-concave lens are aspheric, and both surfaces of said third convex-concave lens are aspheric.

7. The wide-angle projection optical system according to claim 1 wherein said second lens set includes a convex lens.

8. The wide-angle projection optical system according to claim 1 wherein said reflecting mirror has an aspheric shape.

9. The wide-angle projection optical system according to claim 1 wherein said full field angle is larger than ±

70 degrees.

10. A wide-angle projection optical system, from an object side to an image side, said wide-angle projection optical system comprising:

a first lens set configured to provide optical characteristics to match with a light beam coming from said object side;

an aperture stop;

a second lens set arranged behind said aperture stop, and configured to converge said light beam;

a third lens set having negative power, and configured to diverge said light to enlarge a full field angle, wherein said third lens set comprises at least three convex-concave lenses, and both surfaces of each of at least two lenses of said third lens set are aspheric; and

a negative power reflecting mirror arranged in the vicinity of said image side, and configured to further enlarge said full field angle and correct image distortion.

11. The wide-angle projection optical system according to claim 10 wherein said first lens set and said second lens set have positive power.

12. The wide-angle projection optical system according to claim 10 wherein said first lens set, said second lens set, said third lens set and said reflecting mirror have a common optical axis, and said optical axis is shifted with respect to a center of a micro display.