Projection lens and system

• US 6,220,713 B1
• Filed: 10/23/1998
• Issued: 04/24/2001
• Est. Priority Date: 10/23/1998
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Compaq Computer Corporation (HP Inc.)
• Inventors: Fischer, Robert E., Kappel, David, Condra, Neil L., Muscato, Ann M., Donnelly, Sean M., Tadic-Galeb, Biljana
• Primary Examiner(s): Dang, Hung Xuan
• Application Number:
  US09/177,931
• Time in Patent Office: 914 Days
• Field of Search: 359/649, 359/642, 353/77, 353/74
• US Class Current: 353/77
• 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 27/0068 having means for controlling the degree of correction, e.g. using phase modulators, movable elements controlling the phase of light using moving or deformable elements G02B26/06
• CPC Class Codes: G03B 21/10 Projectors with built-in or built-on screen
• CPC Class Codes: G03B 21/2073 Polarisers in the lamp house peculiar to electronic spatial light modulators H04N9/3197
• CPC Class Codes: G03B 21/28 Reflectors in projection beam in illumination beam G03B21/2066

Abstract

Projection lenses and projection lens systems are telecentric between an illumination subsystem and a set of imagers. The lenses and systems can exhibit color fringing correction, uniform imager illumination, athermalization, and component articulation for improved imaging. The lenses and systems may be employed in display apparatuses, such as folded display apparatuses that have decreased footprint size, but long effective projection lengths.

Claims

1. A projection lens system, comprising:

an illumination subsystem comprising

a light source, and

a lightguide adapted to direct illumination light from the light source;

a projection lens comprising

a front lens unit,

a back lens unit, and

a reflecting linear polarizer adapted to direct the illumination light from the lightguide to the back lens unit and to direct image light to the front lens unit; and

an imager adapted to impart image information on the image light.

2. The projection lens system of claim 1, wherein the lightguide comprises a tapered light pipe.

3. The projection lens system of claim 1, wherein the lightguide is adapted to provide the illumination light to the imager as substantially telecentric light.

4. The projection lens system of claim 1, wherein the lightguide comprises a compound parabolic concentrator.

5. A method of projecting light, comprising:

directing light from a light source to a lightguide;

directing the light that is substantially telecentric light from the lightguide to a projection lens;

directing a portion of substantially telecentric light having a certain polarization toward an imager associated with a projection lens;

imparting an image on the portion of the light having polarization rotated; and

directing the image from the projection lens.

6. The method of claim 5, further comprising:

directing another portion of the substantially telecentric light having a polarization substantially orthogonal to the certain polarization back toward the light source.