Off-axis image projection display system

• US 6,398,364 B1
• Filed: 10/06/1999
• Issued: 06/04/2002
• Est. Priority Date: 10/06/1999
• Status: Expired due to Term

• Current Assignee: Viavi Solutions, Inc. (Lumentum Holdings Inc.)
• Original Assignee: Optical Coating Laboratory, Inc. (Lumentum Holdings Inc.)
• Inventors: Bryars, Brett J.
• Primary Examiner(s): DOWLING, WILLIAM C
• Application Number:
  US09/414,751
• Time in Patent Office: 972 Days
• Field of Search: 353/20, 353/31, 353/33, 353/34, 353/37, 349/7, 349/8, 349/9, 349/96
• US Class Current: 353/31
• CPC Class Codes: G02B 27/1086 operating by diffraction only
• CPC Class Codes: G02B 27/126 The splitting element being a prism or prismatic array, including systems based on total internal reflection
• CPC Class Codes: G02B 27/149 using crossed beamsplitting surfaces, e.g. cross-dichroic cubes or X-cubes
• CPC Class Codes: H04N 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28

Abstract

An image projection display system is provided which utilizes an off-axis illumination configuration. A beam splitter is configured to direct a first light beam along a first optical path toward reflective imaging devices adapted to direct a second light beam along a second optical path to produce an image to be projected. Polarizing devices are interposed between the beam splitter and each imaging device, with the polarizing devices configured to allow passage of a first polarized component of the light beam while blocking passage of a second polarized component of the light beam. The display system provides a high contrast ratio and degree of brightness which significantly improves the final image quality projected to a display screen.

Claims

1. An image projection display system, comprising:

(a) a light source adapted to generate a first non-polarized light beam;

(b) a beam splitter configured to direct the first light beam along a first optical path;

(c) at least one reflective imaging device disposed in the first optical path and adapted to direct a second light beam along a second optical path to produce an image to be projected; and

(d) at least one polarizing device interposed between the beam splitter and the imaging device, the polarizing device configured to receive at least a portion of the first non-polarized light beam and transmit a first polarized component of the first light beam while blocking passage of a second polarized component of the first light beam.

2. The display system of claim 1, wherein the beam splitter comprises a pair of prisms having an air gap therebetween.

3. The display system of claim 1, wherein the reflective imaging device is selected from the group consisting of a spatial light modulator, a liquid crystal light valve, a liquid crystal on silicon imager, and a ferroelectric liquid crystal display.

4. The display system of claim 1, wherein the polarizing device is a linear polarizer or a circular polarizer.

5. The display system of claim 1, wherein the polarizing device is composed of an absorptive material.

6. The display system of claim 1, further comprising a color splitting assembly disposed along the first and second optical paths between the beam splitter and the reflective imaging device.

7. The display system of claim 6, wherein the color splitting assembly is selected from the group consisting of an x-prism, Philips prism, L-prism, one or more dichroic filters, one or more dichroic mirrors, and a holographic filter.

8. The display system of claim 1, wherein the reflective imaging device is adapted for a continuous modulation of polarization states to transmit a substantially continuous gray scale image.

9. The display system of claim 1, wherein the reflective imaging device has a plurality of energizable imager elements adapted to modulate the first light beam such that light reflected from the imager elements that are not energized has a different polarization state than light reflected from the imager elements that are energized.

10. The display system of claim 1, wherein the reflective imaging device has a plurality of energizable imager elements adapted to modulate the first light beam such that light reflected from the imager elements that are not energized undergoes a rotation of polarization state, while light reflected from the imager elements that are energized does not change in polarization state.

11. A color image projection display system, comprising:

(a) a light source adapted to generate a first non-polarized light beam;

(b) a beam splitter configured to direct the first light beam along a first optical path;

(c) a plurality of reflective imaging devices disposed in the first optical path and adapted to direct a sound light beam along a second optical path to produce an image to be projected;

(d) a color splitting assembly disposed along the first and second optical path between the beam splitter and the reflective imaging devices; and

(e) a plurality of polarizing devices interposed between the color splitting assembly and the reflective imaging devices, each of the polarizing devices configured to receive at least a portion of the first non-polarizing light beam and transmit a first polarized component of the first light beam while blocking passage of a second polarizing component of the first light beam.

12. The display system of claim 11, wherein the beam splitter comprises a pair of prisms having an air gap therebetween.

13. The display system of claim 11, wherein the reflective imaging devices are selected from the group consisting of a spatial light modulator, a liquid crystal light valve, a liquid crystal on silicon imager, and a ferroelectric liquid crystal display.

14. The display system of claim 11, wherein the polarizing devices are linear polarizers or circular polarizers.

15. The display system of claim 11, wherein the polarizing devices are composed of an absorptive material.

16. The display system of claim 11, wherein the color splitting assembly is selected from the group consisting of an x-prism, Philips prism, L-prism, one or more dichroic filters, one or more dichroic mirrors, and a holographic filter.

17. The display system of claim 11, wherein the reflective imaging devices are adapted for continuous modulation of polarization states to transmit a substantially continuous gray scale image.

18. The display system of claim 11, wherein the reflective imaging devices have a plurality of energizable imager elements adapted to modulate the first light beam such that light reflected from the imager elements that are not energized has a different polarization state than light reflected from the imager elements that are energized.

19. The display system of claim 11, wherein the reflective imaging devices have a plurality of energizable imager elements adapted to modulate the first light beam such that light reflected from the imager elements that are not energized undergoes a rotation of polarization state, while light reflected from the imager elements that are energized does not change in polarization state.

20. A color image projection display system, comprising:

(a) a light source adapted to generate a first non-polarized light beam;

(b) a beam splitter configured to direct the first light beam along a first optical path;

(c) a plurality of reflective imaging devices disposed in the first optical path and adapted to direct a second light beam along a second optical path to produce an image to be projected;

(d) a color splitting assembly disposed along the first and second optical paths between the beam splitter and the reflective imaging devices, the color splitting assembly adapted to cause the first light beam to split into a first color component, a second color component, and a third color component which are each directed to one of the reflective imaging devices;

(e) a plurality of polarizing devices each of which are interposed between the color splitting assembly and one of the reflective imaging devices, each of the polarizing devices configured to receive at least one of the color components of the first non-polarized light beam and transmit a first polarized component of one color component of the first light beam while blocking passage of a second polarized component of the transmitted color component of the first light beam;

(f) a projection lens arrangement for receiving the second light beam from the beam splitter; and

(g) a display screen for receiving a projected image from the projection lens arrangement.

21. The display system of claim 20, wherein the beam splitter comprises a pair of prisms having an air gap therebetween.

22. The display system of claim 20, wherein the reflective imaging devices are selected from the group consisting of a spatial light modulator, a liquid crystal light valve, a liquid crystal on silicon imager, and a ferroelectric liquid crystal display.

23. The display system of claim 20, wherein the polarizing devices are linear polarizers or circular polarizers.

24. The display system of claim 20, wherein the polarizing devices are composed of an absorptive material.

25. The display system of claim 20, wherein the color splitting assembly is selected from the group consisting of an x-prism, Philips prism, L-prism, one or more tilted dichroic filters, one or more tilted dichroic mirrors, and a holographic filter.

26. The display system of claim 20, wherein the reflective imaging devices are adapted for continuous modulation of polarization states to transmit a substantially continuous gray scale image.

27. The display system of claim 20, wherein the reflective imaging devices have a plurality of energizable imager elements adapted to modulate the first light beam such that light reflected from the imager elements that are not energized has a different polarization state than light reflected from the imager elements that are energized.

28. The display system of claim 20, wherein the reflective imaging devices have a plurality of energizable imager elements adapted to modulate the first light beam such that light reflected from the imager elements that are not energized undergoes a rotation of polarization state, while light reflected from the imager elements that are energized does not change in polarization state.

29. The display system of claim 20, further comprising a light condenser system disposed between the light source and the beam splitter.

30. The display system of claim 29, wherein the light condenser system comprises components selected from the group consisting of infrared filters, ultraviolet filters, and combinations thereof.

31. The display system of claim 20, wherein the reflective imaging devices are oriented with respect to the beam splitter so as to be located within the height of the beam splitter.