Image projection system engine assembly

• US 6,390,626 B2
• Filed: 10/17/1996
• Issued: 05/21/2002
• 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:
  US08/730,818
• Publication Number:
  US 20010012092A1
• Time in Patent Office: 2,042 Days
• Field of Search: 353/20, 353/31, 353/33, 353/34, 353/37, 353/84, 349/9, 349/8, 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; and

an image engine adapted to receive one of the first or second polarization components and to return to said wide angle reflecting polarizer a polarized image in which polarization of the one of the first or second polarization components is shifted corresponding to an image to display to include portions of the second or first polarization components, wherein the image engine further includes a prism for splitting rays of polarized light received from the reflecting polarizer into the first and second color band, wherein the first color band is passed through a color wheel/shutter to a single LCD for color sequential operation, and wherein the second color band is passed to a second LCD.

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

3. The apparatus of claim 1, further comprising a mirror positioned on an opposite side of the wide angle reflecting polarizer with respect to the light source.

4. The apparatus of claim 1, further comprising a means of modifying the direction of the rays of light.

5. The apparatus of claim 1, further comprising:

a projection apparatus for producing an image display on a display surface, the projection apparatus including;

a display surface;

an optical device; and

means for transmitting 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.

6. The apparatus of claim 1, wherein the image engine receives the first polarized portion passed through said wide angle reflecting polarizer.

7. The apparatus of claim 1, wherein the image engine receives the second polarized portion reflected from said wide angle reflecting polarizer.

8. 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.

9. 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 substantially 45°

from a surface formed by the reflecting polarizer.

29. The projection display apparatus of claim 1, wherein the wide-angle polarizer is adapted to be positioned at approximately 45 degrees relative to the light beam.

30. The projection display apparatus of claim 1, wherein the wide-angle polarizer is adapted to be positioned relative to the light beam at angles substantially away from any Brewster angle of the light beam entering the wide-angle polarizer.

31. The projection display apparatus of claim 1, wherein all the light of the second polarization component of the light beam reflected by the wide-angle polarizer is reflected from a same surface of the wide-angle polarizer.

32. The projection display apparatus of claim 1, wherein all the light of the second polarization component of the light beam reflected by the wide-angle polarizer is reflected into the same optical path.

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

10. A projection display apparatus comprising:

a source of rays of polarized light;

a wide angle reflecting polarizer aligned at an angle to the rays of polarized light for passing substantially all of the rays of polarized light which are polarized in a first direction and for reflecting substantially all of the rays of polarized light which are polarized in a second direction;

a prism for splitting incident rays of polarized light from the reflecting polarizer into a first and second color bands of rays;

a color wheel/shutter for receiving the first color band of rays from the prism and for sequentially passing rays of a first color and of a second color in the first color band;

a first reflecting polarizing LCD for receiving the sequentially passed rays of the first color and of the second color in the first color band, for shifting the polarization of none, some, or all of the sequentially passed rays, and for directing the rays back into the prism;

a second reflecting polarizing LCD for receiving the second color band for rays from the beam splitter/combiner, for shifting the polarization of none, some, or all of the second color band of rays, and for directing the rays back into the prism; and

a lens for receiving and transmitting substantially all of the rays of polarized light whose polarity has been shifted and which have passed from the prism to the wide angle reflecting polarizer.

11. The apparatus of claim 10, wherein the wide angle reflecting polarizer comprises a double brightness enhancement film.

12. The apparatus of claim 10, wherein the first color band is green and blue and wherein the second color band is red.

13. A projection display apparatus comprising:

a source of rays of polarized light;

a wide angle reflecting polarizer aligned at an angle to the rays of polarized light for passing substantially all of the rays of polarized light which are polarized in a first direction and for reflecting substantially all of the rays of polarized light which are polarized in a second direction;

a prism for splitting incident rays of polarized light from the reflecting polarizer into a first and second color bands of rays;

a color wheel/shutter for receiving the first color band of rays from the prism and for sequentially passing rays of a first color and of a second color in the first color band;

a first reflecting polarizing LCD for receiving the sequentially passed rays of the first color and of the second color in the first color band, for shifting the polarization of none, some, or all of the sequentially passed rays, and for directing the rays back into the prism;

a second reflecting polarizing LCD for receiving the second color band for rays from the prism, for shifting the polarization of none, some, or all of the second color band of rays, and for directing the rays back into the prism;

a lens for receiving and transmitting substantially all of the rays of polarized light whose polarity has been shifted and which have passed from the prism to the wide angle reflecting polarizer; and

a display surface for receiving rays from the lens.

14. The apparatus of claim 13, further comprising:

an optical device interposed between the lens and the display surface such that the rays travel an image path which reaches the optics twice before reaching the display surface, wherein the optical device is reflective of some light and transmissive of other light.

15. The apparatus of claim 13, wherein the wide angle reflecting polarizer comprises a double brightness enhancement film.

16. The apparatus of claim 13, wherein the first color band is green and blue and wherein the second color band is red.

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

a wide angle reflecting polarizer for passing substantially all of a first polarized portion of the beam that is polarized in a first direction, and reflecting substantially all of a second polarized portion of the beam that is polarized in a second direction; and

an image engine that receives one of the first or second polarized portions and returns to said wide angle reflecting polarizer a polarized image in which the polarization of the one of the first or second polarized portions is shifted corresponding to an image to display to include components of the second or first polarized portions, wherein the image engine further includes a prism for splitting rays of polarized light received from the reflecting polarizer into a first and second color band, wherein the first color band is passed through a color wheel/shutter to a single LCD for color sequential operation, and wherein the second color band is passed to a second LCD.

18. The apparatus of claim 17, wherein the wide angle reflecting polarizer comprises a double brightness enhancement film.

19. The apparatus of claim 17 further comprising a mirror positioned on an opposite side of the wide angle reflecting polarizer with respect to the light source.

20. The apparatus of claim 17, further comprising a means of modifying the direction of the rays of light.

21. The apparatus of claim 17, further comprising:

a projection apparatus for producing an image display on a display surface, the projection apparatus including;

a display surface;

an optical device; and

means for transmitting light from the image engine to the display surface such that the light travels an image path wich 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.

22. The apparatus of claim 17, wherein the image engine receives the first polarized portion passed through said wide angle reflecting polarizer.

23. The apparatus of claim 17, wherein the image engine receives the second polarized portion reflected from said wide angle reflecting polarizer.

24. The apparatus of claim 17, 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.

25. The apparatus of claim 17, wherein the beam of light is directed from the light source to the wide angle reflecting polarizer at an angle other than substantially 45°

from a surface formed by the reflecting polarizer.

26. A projection display apparatus comprising:

light source providing a beam of light;

a wide angle reflecting polarizer for passing substantially all of a first polarized portion of the beam that is polarized in a first direction, and reflecting substantially all of a second polarized portion of the beam that is polarized in a second direction;

an image engine that receives one of the first or second polarized portions and returns to said wide angle reflecting polarizer a polarized image in which the polarization of the one of the first or second polarized portions is shifted corresponding to an image to display to include components of the second or first polarized portion; and

a projection apparatus for producing an image display on a display surface, the projection apparatus comprising;

a display surface,

an optical device, wherein the optical device is reflective of some light and transmissive other light, and

means for transmitting light from the optical device to the display surface, wherein the means for transmitting light comprises an achromatic retarder, such that the light travels an image path that reaches the optical device twice and is retarded by the achromatic retarder on its way to the display surface.

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

34. The projection display apparatus of claim 26, wherein the optical device comprises a double brightness enhancement film.

39. The apparatus of claim 26, further comprising a reflecting device positioned on an opposite side of the wide angle reflecting polarizer with respect to the light source, wherein the reflecting device is configured for reflecting light of the first polarized portion through the wide angle reflecting polarizer to the light source.

27. A method of producing a visual image comprising:

providing a light source providing a beam of light;

directing the light onto a wide angle reflecting polarizer for passing substantially all of a first portion of the beam which is polarized in a first direction and for reflecting substantially all of a second portion of the beam which is polarized in a second direction;

receiving one of the first or second portions in an image engine;

shifting the polarity of the one of the first or second portions corresponding to an image to be displayed to include components of the second or first portion to yield a polarized image; and

returning the polarized image to the wide angle reflecting polarizer wherein the method is performed in a projection apparatus for producing an image display on a display surface, the projection apparatus comprising;

a display surface,

the wide angle reflecting polarizer, and

means for transmitting light from the wide angle reflecting polarizer to the display surface, wherein the means for transmitting light comprises an achromatic retarder, such that the light travels an image path that reaches the wide angle reflecting polarizer twice and is retarded by the achromatic retarder on its way to the display surface.

35. The method of claim 27, wherein the wide angle reflecting polarizer comprises a double brightness enhancement film.

36. The method of claim 27, wherein the optical device comprises a double brightness enhancement film.

40. The method of claim 27, further comprising providing a reflecting device on an opposite side of the wide angle reflecting polarizer with respect to the light source, wherein the reflecting device is configured for reflecting the first portion of the beam through the wide angle reflecting polarizer to the light source.

28. A projection system comprising:

a source of rays of polarized light;

a wide angle reflecting polarizer aligned at an angle to the rays of polarized light for passing substantially all of the rays of polarized light which are polarized in a first direction and for reflecting substantially all of the rays of polarized light which are polarized in a second direction;

a beam splitter/combiner, having a first, primary incidence plane aligned at an angle to the wide angle reflecting polarizer, for splitting incident rays of polarized light from the reflecting polarizer into a first second, and third color of light rays;

a first reflecting polarizing LCD for receiving the first color of light rays from the beam splitter/combiner, shifting the polarization of none, some, or all of the first color of light rays, and directing the first color of light rays back into the beam splitter/combiner;

a second reflecting polarizing LCD for receiving the second color of light rays from the beam splitter/combiner, shifting the polarization of none, some, or all of the second color of light rays, and directing the second color of light rays back into the beam splitter/combiner;

a third reflecting polarizing LCD for receiving the third color of light rays from the beam splitter/combiner, shifting the polarization of none, some, or all of the third color of light rays, and directing the third color of light rays back into the beam splitter/combiner;

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

a display surface for receiving rays from the lens; and

an optical device interposed between the lens and the display surface such that the rays travel an image path that reaches the optics twice, passing through an achromatic retarder, before reaching the display surface, wherein the optical device is reflective of some light and transmissive of other light.

37. The projection system of claim 28, wherein the wide angle reflecting polarizer comprises a double brightness enhancement film.

38. The projection system of claim 28, wherein the optical device comprises a double brightness enhancement film.

41. The apparatus of claim 28, further comprising a reflecting device positioned on an opposite side of the wide angle reflecting polarizer with respect to the source of rays of polarized light, wherein the reflecting device is configured for reflecting light polarized in the first direction through the wide angle reflecting polarizer to the light source.