Compact, telecentric projection lenses for use with pixelized panels

• US 6,563,650 B2
• Filed: 01/17/2001
• Issued: 05/13/2003
• Est. Priority Date: 01/17/2001
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Moskovich, Jacob
• Primary Examiner(s): Ben, Loha
• Assistant Examiner(s): HASAN, MOHAMMED A
• Application Number:
  US09/764,820
• Publication Number:
  US 20020141072A1
• Time in Patent Office: 846 Days
• Field of Search: 359/663, 359/649, 359/648, 359/745, 359/750, 359/751-753
• US Class Current: 359/663
• CPC Class Codes: G02B 13/04 Reversed telephoto objectives
• 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 13/22 Telecentric objectives or lens systems

Abstract

Telecentric projection lenses for use with pixelized panels (PP) are provided. The projection lenses have a negative first unit (U1) which has at least one negative meniscus element (N1) having at least one aspheric surface and a positive second unit (U2) which has at least one positive element (P1) having at least one aspheric surface. The lens'"'"' aperture stop (AS) is located between the two units, and a third lens unit (U3) may be used in the vicinity of the aperture stop to improve the correction of axial color. The lenses have small forward vertex distances, small clear apertures, and long back focal lengths which make them particularly well-suited for use in the manufacture of compact projection systems.

Claims

1. A projection lens for forming an image of a pixelized panel said projection lens having a long conjugate side and a short conjugate side and comprising in order from said long conjugate side to said short conjugate side of:

(A) a first lens unit having a negative power and comprising at least one negative lens element of overall meniscus shape, said negative lens element being convex towards the long conjugate side and comprising at least one aspheric surface; and

(B) a second lens unit having a positive power, said second lens unit being separated from the first lens unit by an axial space and comprising at least one positive lens element which comprises at least one aspheric surface;

wherein;

(i) the projection lens is telecentric on the short conjugate side;

(ii) the projection lens has an effective focal length f₀, an effective back focal length BFL, and a forward vertex distance FVD which satisfy the following relationships;

2. The projection lens of claim 1 wherein:

3. The projection lens of claim 1 wherein:

(i) the projection lens comprises a plurality of lens elements each of which has a clear aperture;

(ii) the maximum clear aperture diameter is D; and

(iii) D satisfies the relationship;

4. The projection lens of claim 3 wherein:

5. The projection lens of claim 1 wherein:

6. The projection lens of claim 1 wherein each of the first and second lens units comprises a color correcting doublet.

7. The projection lens of claim 1 wherein the projection lens comprises an aperture stop located in the axial space between the first lens unit and the second lens unit.

8. The projection lens of claim 7 wherein the projection lens comprises a third lens unit located in the vicinity of the aperture stop.

9. The projection lens of claim 8 wherein the third lens unit comprises at least one color correcting doublet.

10. A projection lens system comprising:

(a) a pixelized panel; and

(b) the projection lens of claim 1.

11. The projection lens systems of claim 10 further comprising an illumination system which comprises a light source and illumination optics which forms an image of the light source.