Efficient two-panel projection system employing complementary illumination

• US 6,280,034 B1
• Filed: 07/30/1999
• Issued: 08/28/2001
• Est. Priority Date: 07/30/1999
• Status: Expired due to Fees

• Current Assignee: Philips Electronics North America Corporation (Koninklijke Philips N.V.)
• Original Assignee: Philips Electronics North America Corporation (Koninklijke Philips N.V.)
• Inventors: Brennesholtz, Matthew S.
• Primary Examiner(s): DOWLING, WILLIAM C
• Application Number:
  US09/365,210
• Time in Patent Office: 760 Days
• Field of Search: 353/20, 353/31, 353/33, 353/34, 353/37, 353/84, 349/9, 349/8, 349/7, 349/5, 349/18, 349/97, 349/106, 349/115, 349/117, 359/490, 359/501, 359/502, 359/634, 348/742, 348/743
• US Class Current: 353/20
• CPC Class Codes: H04N 9/3117 by using a sequential colour filter producing two or more colours simultaneously, e.g. by creating scrolling colour bands

Abstract

An imaging system, comprising a broadband unpolarized white light source (81), a polarization converter system for converting polarization axes of unpolarized white light into a substantially single polarization axis, to produce a beam of polarized light, a selective polarization filter (82), adapted to selectively rotate a polarization axis of a selected spectral band of light of the with respect to remaining polarized light based on a control signal (119), a polarized beam splitter (84), for separating light having a the substantially single polarization axis from light having a rotated polarization axis, a pair of electro-optic spatial light modulators (86, 89), disposed along a path of light within the spectral band and a path of remaining light outside the spectral band, respectively, and being adapted to modulate an image therein, and a polarized beam splitter (88), for recombining modulated light from the pair of light modulators. In a preferred embodiment, the selective polarization filter (82, 72) is divided into a plurality of regions (70, 71), each adapted to independently and selectively rotate a polarization axis of a selected spectral band of light of the with respect to remaining polarized light.

Claims

1. An imaging system, comprising:

a broadband light source;

a selective beamsplitter, adapted to spatially separate light within a controllably selected spectral band from light outside said controllably selected spectral band, the beamsplitter being electronically controllable to select said controllably selected spectral band by varying what range of wavelengths is included within said controllably selected spectral band; and

a pair of light modulators, being respectively disposed along the path of light within said controllably selected spectral band and within said light outside said controllably selected spectral band.

2. The imaging system according to claim 1, wherein said broadband light source (81) comprises an unpolarized white light source having various polarization angles and a polarization converting system for converting said unpolarized white light into polarized white light having substantially a single polarization axis.

3. The imaging system according to claim 1, wherein said selective beamsplitter (82, 84) comprises a selective polarization converter (82), adapted for controllably rotating a polarization angle of a selected spectral band of light with respect to said light outside said controllably selected spectral band, and a polarizing beamsplitter, for spatially separating the selected wavelength band of light outside said controllably selected spectral band.

4. The imaging system according to claim 1, wherein said pair of light modulators (86, 89) each comprise an electro-optic spatial light modulator.

5. The imaging system according to claim 1, wherein said pair of light modulators (86, 89) each comprise an LCD imaging panel.

6. The imaging system according to claim 1, wherein said selective beamsplitter (82, 84) is electrically controllable (119) to rotate a polarization axis of a selected color band.

7. The imaging system according to claim 1, wherein said selective beamsplitter (82, 84) is based on cholesteric materials.

8. The imaging system according to claim 1, wherein said selective beamsplitter (82, 84) provides control over a spatial pattern of spectral band separation (72).

9. The imaging system according to claim 1, wherein said selective beamsplitter (82, 84) generates a scrolling scan of respectively differing spectral bands (101, 102, 103, 104, 105, 106, 107).

10. The imaging system according to claim 1, further comprising a beamsplitter (88) for recombining modulated light within said controllably selected spectral band and modulated light outside said controllably selected spectral band.

11. The imaging system according to claim 1, wherein said light modulator (86) disposed along a path of light within said controllably selected spectral band modulates red, green and blue light and said light modulator (89) disposed along a path of light outside said controllably selected spectral band modulates cyan, magenta and yellow light.

12. The imaging system according to claim 1, further comprising means (119) for varying the selected spectral band over time.

13. An imaging method, comprising:

providing a broadband light source;

electronically controlling a selective beamsplitter to controllably select a spectral band and to split the output of the broadband light source to selectively spatially separate light within the controllably selected spectral band from light outside the controllably selected spectral band; and

separately spatially modulating light disposed along the path of light within the controllably selected spectral band and light outside the controllably selected spectral band.

14. The imaging method according to claim 13, wherein the selective beamsplitter controllably rotates a polarization angle of a selected spectral band of light with respect to said light outside said controllably selected spectral band, and spatially separates the selected wavelength band of light outside said controllably selected spectral band.

15. The imaging method according to claim 13, wherein the splitting step is controlled electrically to rotate a polarization axis of a selected color band.

16. The imaging method according to claim 13, wherein the splitting step is controlled mechanically.

17. The imaging method according to claim 13, wherein light disposed along a path of light within said controllably selected spectral band comprises red, green or blue light at any spatial location and light disposed along a path of light outside said controllably selected spectral band comprises cyan, magenta, or yellow light at any spatial location.