Image projection system engine assembly

• US 6,746,122 B2
• Filed: 04/12/2002
• Issued: 06/08/2004
• Est. Priority Date: 10/17/1996
• Status: Expired due to Fees

• Current Assignee: Duke University
• Original Assignee: Duke University
• Inventors: Knox, Richard M.
• Primary Examiner(s): DOWLING, WILLIAM C
• Application Number:
  US10/120,845
• Publication Number:
  US 20020159034A1
• Time in Patent Office: 788 Days
• Field of Search: 353/20, 353/31, 353/33, 353/34, 353/37, 353/84, 353/98, 349/8, 349/9, 349/5, 348/742, 348/743
• US Class Current: 353/20
• CPC Class Codes: F21V 9/14 for producing polarised light
• CPC Class Codes: F21V 9/20 Dichroic filters, i.e. devices operating on the principle of wave interference to pass specific ranges of wavelengths while cancelling others
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: H01J 61/025 Associated optical elements
• CPC Class Codes: H01J 61/12 Selection of substances for gas fillings; Specified operating pressure or temperature
• CPC Class Codes: H01J 61/34 Double-wall vessels or containers
• CPC Class Codes: H01J 61/40 by light filters; by coloured coatings in or on the envelope
• CPC Class Codes: H01J 65/046 the field being produced by using capacitive means around the vessel
• CPC Class Codes: H04N 5/7441 the modulator being an array of liquid crystal cells
• CPC Class Codes: H04N 9/3105 for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators simultaneous projection in colour photography G03B33/10; beam splitting or combining systems per se G02B27/10
• CPC Class Codes: H04N 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28

Abstract

A light projection engine uses a wide angle reflecting polarizer material (preferably 3M DBEF brand double brightness enhancement filter) as a polarizing beamsplitter to direct polarized light to beam splitter/combiner (such as an X-cube dichroic reflector). The beam splitter/combiner then splits the directed polarized light into separate reflective LCD panels acting as light valves. The LCD panels alter the polarity of the incident light from 0 degrees up to 90 degrees to control which light is passes from the wide angle reflecting polarizer back towards the light source and which light has the necessary polarization change to allow it to pass from the wide angle reflecting polarizer to the lens system. After reflecting off of the LCD panels, the light goes back through the X-cube dichroic reflector, where it is recombined. The recombined light which is of a first polarity is transmitted from the reflecting polarizer to the lens system, while the recombined light which is of a second polarity is transmitted to the light source. The LCDs are preferably analog polarizing LCDs.

Claims

1. A projection display apparatus comprising:

a light source adapted to provide a light beam;

a wide angle reflecting polarizer adapted to pass substantially all light of a first polarization component of the light beam, and to reflect substantially all light of a second polarization component of the light beam;

a reflective surface positioned to reflect one of the first or second polarization components back towards the wide angle reflecting polarizer;

an image engine adapted to receive one of the first or second polarization components not reflected by the reflective surface and to return to said wide angle reflecting polarizer a polarized image in which polarization of the received polarization component is shifted corresponding to an image to display to include portions of the second or first polarization components.

2. The apparatus of claim 1, wherein the wide angle reflecting polarizer is configured to pass substantially all of the first polarization component of the light beam to the image engine, and the reflective surface is configured to return substantially all of the second polarization component of the light beam via the wide angle reflecting polarizer to the light source for energy recovery.

3. The apparatus of claim 1, wherein the image engine further comprises:

a prism configured to split polarized light received from the reflecting polarizer into first and second color bands;

a first liquid crystal display (LCD) positioned to receive the first color band, and adapted to operate in a color sequential mode; and

a second LCD positioned to receive the second color band.

4. The apparatus of claim 1, wherein the wide angle reflecting polarizer comprises a double brightness enhancement film.

5. The apparatus of claim 1, wherein the image engine further comprises:

a beam splitter/combiner for splitting polarized light received from the reflecting polarizer into a plurality of color bands, wherein the beam splitter/combiner comprises a plurality of planar surfaces;

a respective reflecting polarizing liquid crystal display (LCD) associated with each of the plurality of color bands;

wherein the beam splitter/combiner and the respective reflecting polarizing LCDs are optically coupled such that each color band is directed through a respective planar surface of the beam splitter/combiner to a respective reflecting polarizing LCD, and reflected back to the beam splitter/combiner by the respective reflective polarizing LCD for recombining.

6. The apparatus of claim 5, wherein the LCD is an analog LCD.

7. The apparatus of claim 1, wherein the reflective surface comprises a mirror positioned on an opposite side of the wide angle reflecting polarizer with respect to the light source.

8. The apparatus of claim 1, further comprising means for modifying the direction of the rays of light.

9. The apparatus of claim 1, further comprising:

a projection apparatus configured to produce an image display on a display surface, the projection apparatus including;

a display surface;

an optical device; and

a transmitter configured to transmit light from the image engine to the display surface such that the light travels an image path which reaches the optical device twice on its way to the display surface, in order to reflect light from a display screen at one instance, and in order to pass through the display screen at another instance, wherein the optical device is configured to reflect some light and transmit other light, and the display surface is substantially coextensive with the optical device.

10. The apparatus of claim 1, wherein the image engine receives the first polarization component passed through said wide angle reflecting polarizer.

11. The apparatus of claim 1, wherein the image engine receives the second polarization component reflected from said wide angle reflecting polarizer.

12. The apparatus of claim 1, wherein the beam of light is directed by the light source to the wide angle reflecting polarizer at an angle substantially 45°

from a surface formed by the reflecting polarizer.

13. The apparatus of claim 1, wherein the beam of light is directed by the light source to the wide angle reflecting polarizer at an angle other than 45°

from a surface formed by the wide angle reflecting polarizer.

14. The apparatus of claim 1, wherein the image engine further comprises a color wheel/shutter and an LCD, the color wheel/shutter positioned between the light source and the LCD for color sequential operation, wherein the LCD is adapted to generate a polarized image and to control a brightness of the polarized image.

15. The apparatus of claim 1, wherein the image engine further comprises:

a beam splitter/combiner configured to split polarized light received from the reflecting polarizer into first and second color bands;

a first liquid crystal display (LCD) positioned to receive the first color band and adapted to operate in a color sequential mode; and

a second LCD positioned to receive the second color band.

16. The apparatus of claim 15, further comprising a color wheel/shutter positioned between the beam splitter/combiner and the first LCD.

17. The apparatus of claim 1, wherein all the light having the second polarization component reflected by the wide angle reflecting polarizer is reflected from a common surface of the wide angle reflecting polarizer.

18. The apparatus of claim 1, wherein all the light having the second polarization component reflected by the wide angle reflecting polarizer is reflected onto a common optical path.

19. A method of producing a visual image comprising:

providing a light source configured to provide a beam of light;

directing the light onto a wide angle reflecting polarizer for passing substantially all of a first polarization component of the beam, and for reflecting substantially all of a second polarization component of the beam;

reflecting one of the first or second polarization component back to the light source via the wide angle reflecting polarizer;

receiving, in an image engine, one of the first or second polarization components not reflected back to the light source;

shifting the polarity of the polarization component received by the image engine in accordance with an image to be displayed to include portions of the second or first polarization components to yield a polarized image; and

directing the polarized image to the wide angle reflecting polarizer.

20. The method of claim 19, wherein the wide angle reflecting polarizer comprises a double brightness enhancement film.

21. The method of claim 19, wherein the reflective surface comprises a mirror positioned on an opposite side of the wide angle reflecting polarizer with respect to the light source.

22. The method of claim 19, wherein the image engine comprises a spatial light modulator.

23. The method of claim 19, further comprising modifying the direction of rays of light.

24. The method of claim 19, further comprising providing a projection apparatus for producing an image display on a display surface, the projection apparatus comprising:

a display surface;

an optical device; and

a transmitter configured to transmit light from the image engine to the display surface such that the light travels an image path which reaches the optical device twice on its way to the display surface, for reflecting light from a display screen at one instance, and for passing through the display screen at another instance, wherein the optical device is configured to reflect some light and transmit other light, and the display surface is substantially coextensive with the optical device.

25. A projection system comprising:

a source of polarized light;

a wide angle reflecting polarizer aligned at an angle to propagation direction of the polarized light in order to pass substantially all light which is polarized in a first direction and reflect substantially all light which is polarized in a second direction, and configured to return back to the light source polarized light which is reflected back to the wide angle reflecting polarizer from a reflective surface for energy recovery;

a beam splitter/combiner, having a first primary incidence plane aligned at an angle to the wide angle reflecting polarizer, configured to split incident polarized light from the reflecting polarizer into first, second, and third colors;

a first reflecting polarizing LCD configured to receive the first color from the beam splitter/combiner, shift the polarization of none, some or all of the first color, and direct the first color back into the beam splitter/combiner;

a second reflecting polarizing LCD configured to receive the second color from the beam splitter/combiner, shift the polarization of none, some, or all of the second color, and direct the second color back into the beam splitter/combiner;

a third reflecting polarizing LCD configured to receive the third color from beam splitter/combiner, shift the polarization of none, some, or all of the third color, and direct the third color back into the beam splitter/combiner;

a lens configured to receive and transmit substantially all of the polarized light whose polarity has been shifted and which have passed from the beam splitter/combiner to the wide angle reflecting polarizer; and

a display surface configured to receive light from the lens.

26. The apparatus of claim 25, wherein the wide angle reflecting polarizer comprises a double brightness enhancement film.

27. The apparatus of claim 25, wherein the first, second, and third colors are respectively red, green, and blue.

28. A projection display engine apparatus that receives a beam of light from a light source, comprising:

a wide angle reflecting polarizer configured to pass substantially all of a first polarized portion of the beam that is polarized in a first direction, and to reflect substantially all of a second polarized portion of the beam that is polarized in a second direction;

a reflective surface configured to reflect one of the first and second polarized portions back to the light source via the wide angle reflecting polarizer for energy recovery; and

an image engine configured to receive one of the first or second polarized portions not reflected by the reflective surface and return to said wide angle reflecting polarizer a polarized image in which the polarization of the received polarized portion is shifted corresponding to an image to display, to include components of the second or first polarized portions.

29. The apparatus of claim 28, wherein the image engine further comprises:

a prism configured to polarized light received from the reflecting polarizer into first and second color bands;

a first liquid crystal display (LCD) positioned to receive the first color band, and adapted to operate in a color sequential mode; and

a second LCD positioned to receive the second color band.

30. The apparatus of claim 28, wherein the wide angle reflecting polarizer comprises a double brightness enhancement film.

31. The apparatus of claim 28, wherein the reflective surface comprises a mirror positioned on an opposite side of the wide angle reflecting polarizer with respect to the light source.

32. The apparatus of claim 28, wherein the image engine further comprises:

a beam splitter/combiner for splitting polarized light received from the reflecting polarizer into a plurality of color bands, wherein the beam splitter/combiner comprises a plurality of planar surfaces;

a respective reflecting polarizing liquid crystal display (LCD) associated with each of the plurality of color bands;

wherein the beam splitter/combiner and the respective reflecting polarizing LCDs are optically coupled such that each color band is directed through a respective planar surface of the beam splitter/combiner to a respective reflecting polarizing LCD, and reflected back to the beam splitter/combiner by the respective reflective polarizing LCD for recombining.

33. The apparatus of claim 32, wherein the LCD is an analog LCD.

34. The apparatus of claim 28, further comprising means for modifying the direction of the rays of light.

35. The apparatus of claim 28, further comprising:

a projection apparatus configured to produce an image display on a display surface, the projection apparatus comprising;

a display surface;

an optical device; and

a transmitter configured to transmit light from the image engine to the display surface such that the light travels an image path which reaches the optical device twice on its way to the display surface, for reflecting light from a display screen at one instance, and for passing through the display screen at another instance, wherein the optical device is reflective of some light and transmissive of other light, and the display surface is substantially coextensive with the optical device.

36. The apparatus of claim 28, wherein the image engine receives the first polarized portion passed through said wide angle reflecting polarizer.

37. The apparatus of claim 28, wherein the image engine receives the second polarized portion passed through said wide angle reflecting polarizer.

38. The apparatus of claim 28, wherein the beam of light is directed from the light source to the wide angle reflecting polarizer at an angle substantially 45°

from a surface formed by the reflecting polarizer.

39. The apparatus of claim 28, wherein the beam of light is directed from the light source to the wide angle reflecting polarizer at an angle other than 45°

from a surface formed by the reflecting polarizer.

40. The apparatus of claim 28, wherein the image engine further comprises:

a beam splitter/combiner configured to split polarized light received from the reflecting polarizer into first and second color bands;

a first liquid crystal display (LCD) positioned to receive the first color band and adapted to operate in a color sequential mode; and

a second LCD positioned to receive the second color band.