Optical: systems and elements – Optical modulator – Light wave temporal modulation
Patent
1998-07-02
2000-05-30
Epps, Georgia
Optical: systems and elements
Optical modulator
Light wave temporal modulation
359252, 359254, 359619, G02F 103, G02F 107
Patent
active
060697288
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The field of the invention is that of display devices and in particular that of flat television screens of large dimension, consisting of an active liquid crystal matrix with matrix addressing (LCD).
2. Discussion of the Background
Currently, the construction of flat television screens of large dimensions (thickness less than 5 cm and surface area greater than 1 m.sup.2) constitutes a priority objective in the presentation of high-definition TV colour images. The applications of these screens are extremely varied and cover both the professional sector and the general-public sector.
Hitherto, television images of large dimensions have been produced by projecting the image onto a screen, from a small-size liquid crystal matrix (diagonal less than 5 cm). Several companies are now constructing and marketing front-projection or retroprojection systems. However, these systems are of limited performance in view of the following parameters: dimension.
Under these conditions, it would be particularly beneficial to work towards a truly flat screen with active liquid crystal matrix, of large size and viewed directly with no projection device.
Nevertheless, the extension of current technologies in large-size active liquid crystal matrices is essentially limited by the dimension of the elementary pixels of the said active matrices, necessary in the construction of the flat screen.
Thus, when pixel sizes of the order of a mm.sup.2 are envisaged, such an area of the liquid crystal electrooptical element leads to a considerable capacitance of the pixel. This considerable capacitance hampers the operation of the large-size screen at the video rate. Currently, all of the points of a line (around 800 points) can be addressed in 60 .mu.s, this being made possible by virtue of the small size of the pixels (100 .mu.m.times.100 .mu.m). Such addressing becomes difficult when the size of the elementary pixels is increased beyond this dimension.
SUMMARY OF THE INVENTION
In order to solve this problem, the present invention proposes a display device and in particular a flat television screen, comprising a matrix of large dimension with a pixel size which is small compared with the spacing of the white image points.
By using a compact illuminating device compatible with collimated illumination which exploits the maximum light flux, it becomes possible to obtain a direct view (with no bulky projection optics) flat display screen of large dimensions which can be addressed at the video rate on account of small dimensions of the elementary pixels.
More precisely, the subject of the invention is a display device comprising an illuminating source emitting radiation Ip, and a spatial light modulator illuminated by the radiation Ip, the said modulator consisting of a matrix of N.times.M elementary pixels (X.sub.i,j) of dimensions d.sub.N .times.d.sub.M, the pixels X.sub.i,j and X.sub.i+1,j being separated by a spacing p.sub.N, the pixels X.sub.i,j and X.sub.i,j+1 being separated by a spacing p.sub.M, characterized in that the device comprises means for collimating the radiation Ip in each pixel and in that the spacing p.sub.N is greater by at least an order of magnitude than the dimension d.sub.N.
According to a preferred variant of the invention the spacing p.sub.M is greater by at least an order of magnitude than the dimension d.sub.M.
The subject of the invention is also a colour display device comprising a display device comprising a light source simultaneously emitting several radiations in chromatic component ranges (R, G, B) and a spatial light modulator comprising a matrix of N.times.M elementary dots (D.sub.i,j), each dot including at least one elementary sub-pixel per chromatic component range (X.sub.Ri,j ; X.sub.Gi,j ; X.sub.Bi,j) of dimensions d.sub.N .times.d.sub.M, the sub-pixels X.sub.Ri,j (X.sub.Gi,j ; X.sub.Bi,j) being separated from the sub-pixels X.sub.R(i+1),j (X.sub.G(i+1),j ; X.sub.B(i+1),j) by a spacing pN, the pixels X.sub.Ri,j (X.sub.Gi,j ; X.sub.Bi,j) being s
REFERENCES:
patent: 4451412 (1984-05-01), Loiseaux et al.
patent: 4576434 (1986-03-01), Huignard et al.
patent: 4847521 (1989-07-01), Huignard et al.
patent: 5181054 (1993-01-01), Nicolas et al.
patent: 5206674 (1993-04-01), Puech et al.
patent: 5258969 (1993-11-01), Refregier et al.
patent: 5272496 (1993-12-01), Nicolas et al.
patent: 5323372 (1994-06-01), Puech et al.
patent: 5410421 (1995-04-01), Huignard et al.
patent: 5416617 (1995-05-01), Loiseaux et al.
patent: 5467206 (1995-11-01), Loiseaux et al.
patent: 5526063 (1996-06-01), Joubert et al.
patent: 5546200 (1996-08-01), Nicolas et al.
patent: 5621547 (1997-04-01), Loiseaux et al.
patent: 5652672 (1997-07-01), Huignard et al.
patent: 5680386 (1997-10-01), Le Carvennec et al.
patent: 5734447 (1998-03-01), Loiseaux et al.
patent: 5784181 (1991-11-01), Loiseaux et al.
patent: 5801794 (1995-06-01), Lehureau et al.
patent: 5940050 (1997-01-01), Joubert et al.
patent: 5946114 (1994-06-01), Loiseaux et al.
patent: 5994687 (1997-09-01), Chanteloup et al.
patent: 6014192 (1997-07-01), Lehureau et al.
Delboulbe Anne
Huignard Jean-Pierre
Joubert Cecile
Loiseaux Brigitte
"Thomson-CSF"
Epps Georgia
Lester Evelyn A.
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