Color liquid crystal display device

• US 6,535,256 B1
• Filed: 03/19/1999
• Issued: 03/18/2003
• Est. Priority Date: 03/24/1998
• Status: Expired due to Fees

• Current Assignee: Minolta Corporation Limited (Konica Minolta Inc.)
• Original Assignee: Minolta Corporation Limited (Konica Minolta Inc.)
• Inventors: Konno, Kenji, Ishihara, Jun, Hayashi, Kohtaro
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): NGUYEN, DUNG T
• Application Number:
  US09/272,813
• Time in Patent Office: 1,460 Days
• Field of Search: 349/8, 349/5, 353/31, 353/37
• US Class Current: 349/5
• CPC Class Codes: G02F 1/133621 providing coloured light G02F1/133617, G02F1/133533 take precedence
• CPC Class Codes: G03B 21/006 using LCD's

Abstract

A color liquid crystal display device which separates white light in to component colors. The separated colors are modulated by a reflective liquid crystal display. A lens group between the light separator and the reflective liquid crystal display condenses the entering light to each pixel of the liquid crystal display. High brightness and aperture efficiency are achieved by including in the lens group a birefringent material so that a different optical function is performed relative to the entering light fluxes and the modulated light fluxes.

Claims

1. A color image projection device comprising:

a light source for generating substantially white light;

a separation device for separating white light flux from the white light source into red, green, and blue primary color light fluxes and for deflecting the separated color light fluxes in different directions;

a reflective liquid crystal display element, disposed to receive all of said separated color light fluxes from said separation device, for modulating the separated color light fluxes to form a color image;

a lens unit disposed between the reflective liquid crystal display and the separation device to condense the separated color light fluxes from the separation device onto a plurality of pixels of the reflective liquid crystal display, said lens unit including a birefringent element; and

a projecting device for projecting the separated color light fluxes modulated by the reflective liquid crystal display element.

2. A color image projection device in accordance with claim 1, wherein said lens unit includes at least two birefringent elements.

3. A color image projection device in accordance with claim 1, wherein said lens unit includes a micro lens array.

4. A color image projection device comprising:

a polychromatic light source;

a light separation device for separating a polychromatic light from said light source into a plurality of separated light beams, each separated light beam being substantially monochromatic;

a reflective display device for receiving all of said separated light beams and for selectively reflecting said separated light beams to form a polychromatic image; and

a concentrating device disposed between said light separation device and said reflective display element for concentrating said separated light beams incoming from said light separation device onto said reflective display element.

5. A color image projection device in accordance with claim 4, wherein said concentrating device includes a birefringent element.

6. A color image projection device in accordance with claim 5, wherein said reflective display device includes a plurality of pixels, a portion of said plurality of pixels corresponding to each of said separated light beams from said light separation device.

7. A color image projection device in accordance with claim 6, wherein said concentrating device is adapted to deflect each of said separated light beams from said light separation device to said portion of said plurality of pixels corresponding thereto.

8. A color image projection device in accordance with claim 7, wherein said concentrating device includes a birefringent element, said concentrating device being adapted to deflect each of said separated light beams incoming from said light separation device, and said concentrating device being adapted to not deflect said separated light beams reflected by said reflective display device.

9. A color image projection device in accordance with claim 4, wherein said separated light beams incoming from said light separation device have a linear polarization in a first direction, said first direction being substantially orthogonal to a second direction of linear polarization of said separated light reflected from said reflective display device.

10. A color image projection device in accordance with claim 9, wherein said concentrating device includes a birefringent element so that said separated light beams incoming from said light separation device having a linear polarization in said first direction are refracted to a first extent and said separated light reflected from said reflective display device having a linear polarization in said second direction are refracted to a second extent.

11. A color image projection device in accordance with claim 9, wherein said reflective display device is a reflective-type liquid crystal display assembly, said reflective-type liquid crystal display assembly selectively reflecting said separated light beams incident thereon from said light separation device, said reflective-type liquid crystal display assembly operating to rotate a polarization direction of said separated light beams incident thereon from said first direction to said second direction.

12. A color image projection device in accordance with claim 4, wherein said polychromatic light source includes a polarizing device so that said polychromatic light outputted from said light source is substantially linearly polarized in a first direction.

13. A color image projection device in accordance with claim 12, wherein said light separation device is a dicroic beam splitter.

14. A color image projection device in accordance with claim 13, wherein said concentrating device includes a refractive element and a birefringent element, an axis of said birefringent element being optically oriented relative to said light source so that a first refractive index of said birefringent element, consistent with said first direction, is different than a refractive index of said refractive element, and a second refractive index of said birefringent element, consistent with a second direction orthogonal to said first direction, is substantially equivalent to said refractive index of said refractive element.

15. A color image projection device in accordance with claim 13, further comprising:

a projection optical system for receiving said separated light beams reflected by said reflective display device and-for forming a projected image therefrom; and

a second polarizing device disposed between said reflective display device and said projection optical system for polarizing said separated light beams reflected by said reflective display device.

16. A color image projection device in accordance with claim 12, wherein said concentrating device includes a refractive element and a birefringent element,

each of said refractive element and said birefringent elements having first and second opposing major surfaces, said first major surface of said refractive element being bonded to said first major surface of said birefringent element,

said second major surface of said refractive element being substantially parallel to said second major surface of said birefringent element, and

an axis of said birefringent element being optically oriented relative to said light source so that an optical power of said combination of said refractive element and said birefringent element is substantially zero for a light beam having a polarization direction orthogonal to said first direction.

17. A color image projection device in accordance with claim 16, wherein said refractive element is a micro lens array.

18. A color image projection device in accordance with claim 16, wherein said refractive element is a lenticular micro lens array.

19. A color image projection device in accordance with claim 12, wherein said concentrating device includes two optical assemblies;

a first optical assembly including a micro lens array element and a first birefringent element which are bonded together, a second sub-assembly including a fresnel lens element and a second birefringent element which are bonded together;

an index of refraction of a material comprising said micro lens array being substantially equal to an index of refraction of said first birefringent element along a first orientation thereof, said first optical assembly being oriented relative to said light source so that an optical power of said first optical assembly is substantially zero for a light beam incident thereon having a polarization direction in said first direction; and

an index of refraction of a material comprising said fresnel lens being substantially equal to an index of refraction of said second birefringent element along a first orientation thereof, said second optical assembly being oriented relative to said light source device so that an optical power of said second optical assembly is substantially zero for a light beam incident thereon having a polarization direction orthogonal to said first direction.

20. A color image projection device which comprises:

a light source for generating substantially white light having a linear polarization in a first direction;

a separator for receiving said white light from said light source and separating said white light into a plurality of primary color light beams;

a concentrator for receiving said primary color light beams from said separator and for concentrating said primary color light beams, said concentrator including at least one birefringent element;

a reflective display device, including a plurality of pixels, for receiving said concentrated primary color light beams and for selectively reflecting said concentrated primary color light beams in accordance with an image to be formed; and

a projecting device for projecting said primary color light beams reflected by said reflective display device to form an image.

21. A color image projection device in accordance with claim 20, wherein said concentrator is optically disposed between said separator and said reflective display device and said concentrator is also optically disposed between said reflective display device and said projecting device;

said reflective display is adapted to rotate a polarization of said concentrated primary color light beams from said first direction to a second direction substantially orthogonal to said first direction; and

wherein said concentrator is adapted to concentrate light beams having a polarization direction in said first direction and said concentrator is adapted to not concentrate light beams having a polarization direction in said second direction.

22. A color image projection device in accordance with claim 21, wherein said concentrator includes at least two birefringent elements.

23. A color image projection device in accordance with claim 21, wherein said concentrator includes a micro lens array.

24. A color image projection device in accordance with claim 21, wherein said concentrator includes a lenticular micro lens array.

25. A color image projection device in accordance with claim 21, further comprising a polarizing element optically disposed between said concentrator and said projecting device.

26. A lens device adapted for use with a projector, and to condense separated color light fluxes from a separation device onto a plurality of pixels on a reflective liquid crystal display, said lens device comprising:

a micro-lens array having a plurality of lenses, arranged in a panel-like shape; and

a first material having birefringence characteristics, said first material attached to said micro-lens array, said first material located between said separation device and said micro-lens array.

27. A lens device as claimed in claim 26, wherein said micro-lens array is a lenticular lens.

28. A lens device as claimed in claim 26, further comprising a transparent protective panel located over said first material having birefringence characteristics.

29. A lens device as claimed in claim 28, further comprising a Fresnel lens and a second material having separate birefringence characteristics;

wherein said Fresnel lens is located between said first material having birefringence characteristics and said transparent protective panel and said second material having separate birefringence characteristics is located between said Fresnel lens and said transparent protective panel.