Image display apparatus of liquid crystal valve projection type

• US 4,389,096 A
• Filed: 02/23/1981
• Issued: 06/21/1983
• Est. Priority Date: 12/27/1977
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Hori, Yoshikazu, Asai, Komei, Fukai, Masakazu
• Primary Examiner(s): Corbin, John K.
• Assistant Examiner(s): Gallivan, Richard F.
• Application Number:
  US06/237,471
• Time in Patent Office: 848 Days
• Field of Search: 350/331 R, 350/336, 350/339 R, 350/342, 350/348, 350/361, 350/162 SF, 350/162.17, 350/162.19, 350/162.2, 358/231, 358/232, 358/236, 358/237, 356/406
• US Class Current: 349/5
• CPC Class Codes: G02F 1/1335 Structural association of cells with optical devices, e.g. polarisers or reflectors
• CPC Class Codes: G02F 1/292 by controlled diffraction or phased-array beam steering controlled diffraction for optical switching G02F1/31
• CPC Class Codes: G02F 2203/22 diffractive
• CPC Class Codes: H04N 9/3114 by using a sequential colour filter producing one colour at a time

Abstract

A liquid crystal light valve projection type image display apparatus comprises an electro-optic element and a Schlieren optical system. The electro-optic element has a liquid crystal layer having a dielectric and optical anisotropy. An electric field having a spatial intensity distribution according to an image signal is applied to said liquid crystal at a spatial period, so that a spatially phase-modulated phase diffraction grating is formed in the liquid crystal layer. Thus, a projected image in enlarged form is obtained. The fact that the electric field with a spatial period is applied to the liquid crystal leads to a constant light diffraction angle, and the modulation of the diffraction light intensity in the applied electric field enables an image corresponding to the input image signal to be projected at high light utilization.

Claims

1. A liquid crystal light valve projection color image display apparatus comprising:

an electro-optic element comprising a pair of substrates;

a nematic liquid crystal layer interposed between said substrates and having optic anisotropy;

electric field applying means for applying to said nematic liquid crystal layer a patterned electric field which has a plurality of different striped electric field patterns each associated with a respective different region of said liquid crystal layer to form a plurality of different diffraction gratings, each having a different diffraction pattern;

in said regions of said liquid crystal layer, each of said different diffraction gratings having a respective fixed spatial diffraction period;

means for forming from at least one applied image signal a plurality of color separated input image signals in said electro-optic element each said color separated image signal being formed in a different region of said electro-optic element containing a respective diffraction grating, said electro-optic element forming a plurality of separate diffracted color images from said applied input image by means of said plurality of different diffraction gratings;

means for applying at least one input image signal to said electro-optic element; and

,

a Schlieren optical system for projecting said separate color images formed in said electro-optic element onto a projection surface.

2. An image display apparatus according to claim 1, wherein said plurality of different diffraction gratings are arranged, respectively, in different directions relative to each other.

3. An image display apparatus according to claim 1, wherein said plurality of different diffraction gratings are arranged, respectively, to have a different and fixed spatial period relative to each other.

4. An image display apparatus according to claim 1, wherein said plurality of different diffraction gratings are arranged in sequence.

5. An image display apparatus according to claim 1, wherein said electric field applying means includes respective electrodes on the inside surfaces of said substrates holding said liquid crystal layer, one of said electrodes having a plurality of different stripe configurations arranged in sequence which are different in direction and pitch from one another.

6. An image display apparatus according to claim 1, wherein said electric field applying means comprises a photoconductive layer disposed electrically in series with said liquid crystal layer, and a two-dimensional optical image having a plurality of spatial period intensity distributions is focussed on said photoconductive layer.

7. An image display apparatus according to claim 1, further comprising a light-blocking mask having a plurality of different stripe configurations disposed on a writing input light side of said photoconductive layer.

8. An image display apparatus according to claim 1, wherein said two-dimensional optical image is focussed on said photoconductive layer by a writing light source including a plurality of two-dimensional optical images having spatially periodic light intensity distributions different in pitch and direction.

9. An image display apparatus according to claim 1, wherein said electro-optic element further comprises a photoconductive layer provided on an image receiving side of said electro-optic element, a light mask having a striped pattern for forming said plurality of different diffraction gratings provided on an image receiving side of said photoconductive layer, and a plurality of color filters provided between said photoconductive layer and light mask, each said color filter covering a respective portion of said striped pattern which forms one of said diffraction gratings.

10. An image display apparatus according to claim 9 wherein said electro-optic element further comprises a light absorbing layer provided on a side of said photoconductive layer opposite to said image receiving side and a light reflecting layer provided between said light absorbing layer and said liquid crystal layer.

11. An image display apparatus according to claim 1, wherein said means for applying applies at least two color separated image signals to said electro-optic element.

12. An image display apparatus according to claim 1, wherein said means for applying applies at least three color separated image signals to said electro-optic element.

13. An image display apparatus according to claim 1, wherein said electro-optic element further comprises a photo conductive layer provided on an image receiving side of said electro-optic element, a light mask having a striped pattern for forming said plurality of different diffraction gratings provided on an image receiving side of said photoconductive layer, said photoconductive layer having a plruality of regions of different spectural sensitivity each covering a respective portion of said striped pattern which forms one of said diffraction gratings.

14. An image display apparatus according to claim 13 wherein said electro-optic element further comprises a light absorbing layer provided on a side of said photoconductive layer opposite to said image receiving side and a light reflecting layer provided between said light absorbing layer and said liquid crystal layer.

15. An image display apparatus according to claim 1, wherein said means for applying applies a plurality of color separated image signals to said electro-optic element through respective diffraction grating masks.

16. A liquid crystal light valve projection image display apparatus comprising:

an electro-optic element including a pair of substrates, a nematic liquid crystal layer and a photoconductive layer arranged in series and interposed between said substrates, said nematic liquid crystal layer having a dielectric and optic anisotropy, a light blocking mask having striped openings at a fixed spatial period disposed on an input light side of said photoconductive layer, a first means including said mask and photoconductive layer for supplying a first electric field in a two-dimensional voltage pattern having a fixed striped spatial period to said liquid crystal layer to produce first areas of said layer where the molecules thereof are reoriented away from a predetermined molecular orientation by a voltage potential of said electric field and second areas of said layer not exposed to a voltage potential of said electric field where said molecules continue to have said predetermined molecular orientation, thus forming a phase diffraction grating in said liquid crystal layer, and second means for supplying said liquid crystal layer with a second electric field having a spatially distributed intensity corresponding to an electrical or optical input image signal representing a two-dimensional image;

image supply means for electrically or optically supplying said input image signal to said electro-optic element; and

,

a Schlieren optical system for projecting image information formed in said liquid crystal layer as said phase diffraction grating on a screen by using light diffracted from said phase diffraction grating.