CA2175371A1 - Backlight assembly for an electro-optical display - Google Patents

Abstract

An improved backlight assembly (2) comprising an array of apertures (8) in close proximity to a light source (6), an array of tapered optical elements (10) that have a light input surface area smaller than the light output surface area. Light rays pass through the apertures and are directed to the optical elements which transmit the light rays via internal reflection to provide a partially collimated light source. The light rays then pass through an array of microlenses (12) that transmit the light rays via refraction and provide a substantially more collimated light source for the display elements of a display (16). The backlight assembly is advantageously used as a backlighting means for electro-optical displays, especially those designed for military and avionics applications.

Description

217~371 BACKLIGEIT ASSEMBLY
FOR AN ELECTRO OPTICAL DISPLAY

Ba~ ~oul1d ofthe L~ tion a. Fidd of the L,.e~ltion This in.~nlion is dLc~,l~ to direct view dectro-optical di,~l~." as for example, a liquid crystal display, and more p&li~ LI~, relates to the field of backlit di~,~,l~s particularly adapted for ll~;lit~ and avionics applic~ onR which are ayec;ally d~ to present a bright, uniform d;allilJ~iGn of light in a low profilea~

2s b. Dc~,~;r;ol- of Related Art There hu been an actensive ongo: ~, effort to pro~ide large, full color display systems which do not rely upon the con.e.lt;onal c~hodc ray tube. See, for example,"Flat-PandDisplays,"Srj ~rcA~. e,.c~.,Marchl993,pages90-97. In systems such u tdevision receivas, comrute~ monitors, avionics displ~j;"
3 o aerospace d; pla~ and military-related d;spl~, the dimination of c~hodc ray tube te ~ gy is tesirable. See for example U.S. Patent Nos. 4,843,381, 5128,783 and 5,161,041 for a ~ of the disadvantages of c~hode ray tube te ~1 ~1O3y.
Display devices, as for example, pr~e~ion display devices, off screen display devices and direct view displays are known. See for exunple, EPO 0 525 3 5 7S5 A1; U.S. Patent Nos. 4,659,185, 5,132,830 ant 5,159,478; and Jap~
Nos. 245106 and 42241. Such d;spl~;. are used in a wide range of Ap~ n~ in~ ing televisions, cGl..~ r ~o~ ols, avionics diStJI~a~ aerospace d;;~ i, aUtCilllO~ UIII nl panels and other devices that provide text, graphics or video info~ alion These types of displays can replace cûll~ ional c~thode raytube displays and offer advantages such as lower profile, reduced weight and lower power collCl~mption One display which can e~ n~le the shollcG~ gs of a c~thode ray tube is s the flat panel liquid crystal display (LCD) LCDs are typically either reflective or l~n~ c;~;~re A reflective display is one which ~epe~ s upon ambient light con~itionc in order to view the display A l~ , LCD rc.~ull~s an ill. ~ .;n 1; ~ means or b;~cL liyl~l to ensure that the display image is as bright as possible LCDs, ho. cie., su~fer from a number of inhcr~l~ disa~ ges For 10 example, at high viewing angles (large angles from the d~c lion norrnal to the surface of the display), LCDs exhibit low COI~tl~t and changes in visual cl~ul..~l;c;l~ as the viewing angle ch~.6cs The chara~,l., ;~I;cs of the bArL ligh1;~g scheme are very ,...~,O-~ to both the quality of the image displ~cd by the matrix array of picture P1~n~ of the LCDandthepro eofthedisplay SeeUS PatentNos 5,128,783and5,161,041 for a Aio-cuo-oi~n ofthe defir,ienrieo, in past ba~ g confi~rations Accordil~ , there exists a need in the flat panel electro-optical display field for an improved ligl 1;~g/optical ~,~ n which provides an ~ffirient bright and lmifs~rm image of high conl,~.~ and is capable of being viewed over a wide viewing 20 angle, while ,..,;..lai ,il~ a narrow profile S~lmm~y ofthe Ll~.ltion The present i..~ tion is &~lcd to direct view flat panel d;s~ , having an i,..pro~cd bacldit cle~ onic display which provides an ~,;- 1 bright, Ull;rUIIll25 image with high co-~t.~st and is capable of being viewed over a wide viewing angle An example of a flat panel display is a liquid crystal display which is r. f~ d hc.c..~[l.,r only to d~ r~n~ale a specific applir~tiùn ofthe present h.~ ion and is not; ~IrnAed to lirnit the invention to the precise form A;~,lc~cd The....~,.u.~dbacklitliquidcrystaldisplayc~ ;~g a.~.o~ 9means 3 0 that is capable of prcjecting an image to a l~;...otcl~ pGsi1;r~ned obs_.~.~, the mod~ tin~ means spacedly disl,osed ~om an hllyiO.~ baçl liJ.I asse..lbly CollllJ.i ing a light source in close proA".uly to an ap~,.lwu~g means, wL~.c.ll the dpc.lulin~ means co.nl,.ises an array of apc.lures ol,c.ali~,~ly ~i~posed in close plOAu.uly b~ ,cn the light source and the modulating means; a first means for 35 coll; ~ the divergent light rays ~ n~;~ from the apc.lu,ii~g means, Wh~,.e.;l .

the first coll;~A~ g means is d;;",osed in close pro~,............. ....................................ly b. l-.~" the ape.lul-ng means and the ...o~ means; and a second means for coll; ..-l; .g the light rays n~ from the first CO11;~AI;~8 means, ~Le~... the second col~ t; ~P means is pGs~d in close p,~.,ily b~ h.__n the first coll; ~ g means and the modlllAting 5 means. In an All~ e aspect ofthe il~,e,~lion, the first co!l: ..AI;~g means incoltlola~es the r~ ;o,- ofthe aperture means. In still another aspect ofthe in~ tion, the backlight ass~ "l~ly co...p-ises a light con~ aling means in co..~ ;Qn with a co!l;~ means.
The i,.lpr~e...e.lt in the display ofthe present i,.~,.ltion is that the 10 ap_.lu-i"g means and the first and second co~ l;~ means provide an energy 1 bright and ull;rul~ distributed light source that is provided in a low profile a~f nl.ly.
In one aspect ofthis invention, the ape.lu~ means c,o...~.i~s an array of ap~..lu.es &l~lged in a planar r~ne~;.~g surface. The f~rst co'l ..-l;-~_ means 15 co..~ Ps an array of micr~coll;-..-lo~. The second co!l; nA1;.~g means co..lplises a co..~ ,pon~ g array of microlenses. The microcollimators are tapered optical el~ 1s on a planar substrate having a planar light input surface in close p.o~. ily to the ap_.lu-ing means and a planar light output surface adjacent to the substrate and distal from and parallel to the light input surface, ~. h_re.n the light output 2 0 surface is larger in area than the lignt input surface. Di~ Iight rays from a light source pass lhrou~l the apc. lures to the light input surface of the mia~Coll;~ lols and travel through the array of miaocollimators via total internal l~,n~ ;onc from the sites ofthe miaocollimators. The tapered construction par~ally collimates the light rays so that the output of each miaocollirnqtor be~4---Fs a source of pa lially collimqted light. The output ofthe ll~cloco~ -alGls is ~;r~lcd to a co.l~on~ array of microlenses ~i~rQsed adjacent to the .~I.c-uc~ o~ at the appropl;dle ~ ncc The light is ll~n --.-;l~e~ through each miaolens via refraction and en.e gcs from the array of miaolenses as a s~ .l ;qlly more cd~ Icd Iight source for the ",o~ means.
30 In another aspect ofthe invention, the filnctionc ofthe ape.lu.l.lg means and first co";~ . means are colllb;ned into one set of micl~ CQll;... l;.~g e~1r-.. -~1c The llf.clocQ~ o.~ are tapered optical elc-.. ~ on a planar s~ale having ùr~ sidewalls, a planar light input surface in dûse pruA.----l~ to the light source, ~hae... the input surface fimctions as an ap~ .lu..ng means and a planar lignt output 35 surface ndja.-~nt to the su~ ale and distal from and parallel to the light input W O 95/14255 PC~rnUS94/11894 217~.7 1 surface, ~l.cr~in the light output surface is larger in area than the light input surface.
Uncollims-ted light rays from the light source pass through the array of microcoll; ..a~ol~ via one or more l~n~l;on~ from the .ll.l,o.~d sides ofthe microco!li.~ ol~. The tapered construction partially collima~es the light rays so 5 that the output of each .~;,oCQ~ n~Qr bcco---es a soùrce of partially coll;~ ed light. The output ofthe microcoll;...~ol~ is dirc~,led to a CGI~ pOlld~8 array of microlenses d;~Gsed adjacent to the ,.I.cluco!l;...~ol~ at the appropl;dle ~ ce.The light is h ~ ;1 lcd through each microlens via l~i_hon and l.,.lle.g~S from the array of microlenses as a s~b~t~ lly more CQI~ ed light source for the 10 mod~ i~ means.
In still another aspect of the invention, the a~c, lul~ means co,..l., ;c~,s an array of apcllurcs a.larl~cd in a planar reflecting surface. The first co~ ;ug means Co~ JIi3CS a planar slab oftransparent material and the second co~
means co.~ .l.. ;~P s an array of microlenses. The planar slab of h~spalcnl material of 15 the first cQll~ means caus the light from the apc. ~, means to be directed into a nall~ r angular ~ ;on than would be the case if the volume ~ ncen the ap~ ul~ means and the second cQ!l;...~ g means were filled with air. The output ofthe first coll; ~ g means is dilc~,led to an array of microlenses spacially s~ d to the array of apc~lur~,s and d;s~,Gsed ~ to the first Coll;~t~ g 20 means. The light is h~ ,~,,,i1~fd through each microlens via refraction and C~ ,.gCS
from the array of microlenses as a s~b.,t~-~l;sll), more collimated light source for the mo~uloti~ means.
In still yet another aspect ofthe i..~n~io4 the backlight g~c~ y comprises a light co~-r~ 8 means in combination with a collimating means. The light 25 cQn~ ating means is perferably an array of miclùeonc~ O,~.
~ficlocnnr~ tu.~ are tapered optical el~ rnlc attached to a planar s~ e having a lllu.u.od sidewalls, a planar light input surface adjacent to the ~ aleand a planar output surface distal from and paralld to the light input surface, ~L~dn the area of the light output surface is smaller than the area of the light input 3 0 surface. Uncollimated light rays from the light source pass ~-o~l8h the array of microcon~ ~1.atGl~ via one or more rene~,llons from the ll~l~lùled sides ofthe miclûcQ~ nl~alol~. The tapered construction c~-~c~ tes the light rays so that the output of each micr~col-ce~ alor becGn~s a source of light that is sul.s~ ;AIly smaller in area than the area ofthe light input surface ofthe miC~oconc 1 alor.
3 5 The output of the mic ~Conc~n~ ~ ~lGl ~ is d~ed to a cGll ~s~Q~ 8 array of - 21753~1 microlenses disposed above the microcol~c~ a~ors at the approp-iate .1;~l~ ce.
The light is l.;~ ed through each microlens via refraction and .,.1~ 5CS from the microlenses as a sul~s~ y co!~ ted light source for the mod11lqtin~ means.
In each aspect ofthe invention, the 1lncQllim ~e~ light source may consist of s a single, e~ g~tFA sf~yç~n;~e~ tubular lamo d- fi.~ g a given lighting co.Lgu~lion.
ly, the 1~-coll;~ f d light source may consist of a plurality of discrete tubular lamps, also defi.~ g a given lighting conr~ alion. In n~Aition the ba-1~1ight qcs ..~1~1y may also COlllyliSf a re~ective surface, such as a mirror, ~1;.posed behind the 1mcQllimq~ed light source to redirect stray light rays into the 10 arrayofmicr~col-cf~ alors.
The i...~,.o._d b~ ti~ ~-~n~gf .~enl ofthe present .n~fnlion is able to operate with equal c ~ ...,ss in passiw d;syla~i~ as well as in active matrLx electronic displays. Such displ~s are well known to those skilled in the art tions1 objects, ad~,all~ges and novel features oftne ill~enlion will be set 15 forth in part in the desc ;pt;on which follows, and in part will becGIl,e appare.ll to those skilled in the art upon e ~ l ;OI- of the following or may be learned by pl~liCf ofthe inve.l ic~n. The objects and ad~ ges ofthe invention may be realized and ~ -rd by means ofthe in..tlulll_.l~lities and cc....hil.-l;on~ particularly pointed out in the claims.

BriefDescl;ytiGn Of The Dla~.u~s The above and other objects and adva..~cs ofthis invention will be app~e.~ on consideration oftne following d~ ~ dcs~ iy ion, taken in co.~ I;on 2 5 with the accompanying dla~ 85~ in which like .~fe ~ue charactas refa to like parts ~ ~o~ and in which:
FIGURE 1 is a cross se~,lional view of a liquid crystal display constructed in 2~C~ lUe with one e ~bod: 1 ofthe present ill~ iO4 PIGURE 2A is an ~p1Oded cross se~ view of one e.ll~G~ll_nl of the 3 o bacldight as~sembly in accordance with the present ill~,,lt;on;
FIGI~RE 2B is an exploded cross-sechr~nA1 view of an alternate embodiment of the bacldight ~Qsernhly in accordance with the present i~vention;
FIGURE 3A is a cross-sectional view of one e .~ho~ of the apc. lu, ;ng means of the present i l~enlion, 3 5 FIGURES 3B-3D are a planar views of possible arrangements of the ape lu~i"~; means ofthe present invention;
FIGURE 4 is a cross-section~l view of a single "..crocollimator;
FIGUl~ES 5A-C are pe.~e~ e views of alternate a l~g. ..e ~1S ofthe first co!~ means coll-pl;s;ng an array of microco!~ o,s~
FIGURE 6 is a section view of a single microlens;
FIGURES 7A-C are p~ ,e~ e views of alternate ~l~g ~ 1s ofthe second CQIl;n~;~ means co""),;~",g an array of microlenses;
FIGURES 8A-C are pef5l,e~ , views of sltprnste arrsng~; .f n ~ of the present i.,~c"llion COIlllJl;Slllg an ape,luling means, an array of microcQ~ tc.ls and an array of microlenses;
FIGllRE 9 is an alternate elllbodi~ n1 ofthe present invention co~p~;cin~ a planar slab of ll~jpd~en~ material;
FIGURES lOA-C are p."~pe~ e views of slternste ~l ~g~ ofthe present il.~ ion Colll~)liSing a planar slab of ~ pa~ mstPris1;
FIGURE 1 l is an alt~,."ale embodimpnt ofthe present invention comprising an array of microcol c~ ato,s~
FIGIJRE 12 is a section view of a single mic~oconc~ ~1.alu., FIGI~RES 13A-C are pe. ~,ecli~e views of 91~ e ~1 ~r~8f, . ~1 ~ of the present invention co...~ g an array of .l".,roco1-r~ ~1~alOls, FIGURES 14A-C are pe.~,e~i~e views of-q-hernqte ~l~ g. ~ ofthe present invention CG~ d, an array of microconri~n1~alols and an array of microlenses; and FIGllRES 15A-B illustrate ..~ ~1.n~ls offa~ g rnicrocollimqtors, miCloconce ~1~Gls and rnicrolenses Detailed De3~ ion ofthe ~l~r~ ,d El"bod; ..e l1~
The p,er~.l, d emho~lirnpntc of the present invention will be better understood by those skilled in the art by ..fe~nce to the above figures The plefe,- ~d emho~limpntc of this invention illui.L~ed in the figures are not intpnr~e~ to 3 0 be e~ e or to limit the invention to the precise form ~i~1osPd They are chosen to describe or to best explain the principles ofthe i"~,e"lion and-its applicable and practical use to thereby enable others skilled in the art to best utilize the invention One p-efe.l.,d e"lbod;~n -t of the invention as it applies to an apl,licalion in35 conjunction with a liquid crystal display is shown in Fig 1 l~pre3enled by the wo 95/14255 2 1 7 ~ 3 7 1 PCr/US94/118g4 number 2. The display is co.l-posed of a light genelaling means 6, an optional reflective means 4, an apcllu.ing means 8, a first co~ means 10, a second co~ means 12, an optional input light pol~.~ means 14, a modlllqting means 16, an optional output light po~ means 18 and an image display means 5 20.
The exact fealul~s of light ge.~.~ling means 6, reflective means 4, input light pol~iZ~ means 14, mo~ qti~ means 16, output light pol~i~g means 18 and display means 20 are not critical and can vary widely, and . ny such ~ n, nls convcnl;o--qlly used in the art offlat-panel d;~ , may be employed in the practice 0 ofthis invention. Illllalla~ of useful light g~ a~ means 6 include se.~nli,.e or d;scl~te tube flluor~3chlt lights. Useful r~e~ e means 4 include m~tsll;c l e~e~lol s~ metal coated glass mirrors, phG3~ kor screens, I~,fie~,lo, s coated with white ~c~s such as titanium dioxide layers and the like. r- .~pl~-~ of useful light pol~ g means 14 and 18 are plastic sheeet polaroid m9t~91 and the like.
5 Illu~ ., modlllsti~ means 16 are liquid crystsl cells, ele~,llùcl~lu.llic ...o~ lQrs and lead zirconium l~ ., titanate (PZLT) modulators. The liquid crystal m-ter~91 in liquid crystal cells can vary widely and can be one of several typesin-hl-ling but not limited to, twisted n. ~ ;C (TN) ~..a~e.;al, super-twisted n~o.m-tic (STN) ...~te ;~l and polymer disp~ ed liquid crystal (PDLC) m9t~i91 Such liquid crystal m~t~isl is ~l~2ed in a matruc array of rows and col-lrnnc as is known in the art. The pl~fe.-~d display means 20 is the display means as disclosed in cop~n~ e United States patent application 08/086,414, filed July 1, 1993 and -~;g,.Pd to the -s- ;~ee of the present appl;r -~1 ;on, the ~ ~ of which is inc~,l,oldted herein by ,~f~,;e.lce.
In Fig. 1, light gen~dtu~ means 6 is in close pl~.it~r to ape.lu ul8 me_ns 8, which is in close proAulul~ to first coll;~sti~s means 10, which is in close pr~lul~ to second coll;-.- t;~ means 12, snd second collimating means 12 is in close pro~lul~ to polari~ng mew 14 which itselfis in pro~,l.ul~ to modlllsti~
mew 16. As used herein, "p~AUlUlr" means in ;.~ ph~c~l contact or closely 3o position~l~ preferablywithinlessthanabout 1 inch, d~pr~ guponthe~lr ~n1 and its r..,,.~;~ n Figure 2A shows an exploded s~ n~l view ofthe light gen~alul~, means 6, reflective means 4, aperturing means 8, the first co~ g means 10 and the second ~ll~ means 12. Apc~lu,ùlg means 8 cGll.pli~es a s~ ~dte 21 with 35 refiective regions 24 and l, ul~Lrcnt apc.lule regions 22. First coll;~ e means 10 co,l,~l;3es an array of microcoll;,ll_~ol~ 30. The microcoLIlalol~ 30 are tapered optical ele~ n1~ attached to a planar subsllate 26 via an r~h~;cn promoting layer 28. Microcollimator 30 co,ll~,l;3es a planar light input surface 32 qd;ac ~l to a ll~sp&.,.~l apc.lurc 22 of aperturing means 8, tapered sides 33 and a planar light 5 output surface 34 larger in surface area than the light input surface 32.
Uncollimsted light from the light source 6 passes through the apertures 22 of the apc.lulil~g means 8 and then lhlou~51l the array of mierocolli~ ol~ 30 via totalinternal r~lle~;ol ~ from the sides 33 ofthe microcoll;.. ~to,~. The tapered con -~ u.,l;on causes the light rays at the output of each miclo~ll ~ or to bccoll,c 10 partially coll n.AtcA ~referably, the backlight ~c~ .~l.ly also cc...~ Fs a rçflecting means 4 that reflects stray light rays through apc~alur~ 22.
Second coll;~ means 12 colllt,l;ses a cGIl~ on~ g array of microlenses 40 ~ osed above the microco!~ tGI:i 30. The array of microlenses 40 is attached to s~ ~aLe 36 via an adhesion pro....~t;.~g layer 38. The height of 15 ~ul ;lalcs 26 and 36 is dimensioned to equal the neces-~ ~ d ~t~ ~re beh.~n microco~ .Ator 30 and microcrolens 40 in order to obtain s~lb ~ ;AIly more coll;...-tcd light. The light output of each microcollimator 30 i5 d~,led to a COIl~S~O~ microlens 40. The light llan .,~ through each microlens via refraction and e~ ScS from the microlenses as a substantially more collim~ted light 20 source for the m~ qti~ means 16.
Planar ~lb_~alCS 21, 26 and 36 are trarl..~,ar~l~ to light within the ~a~ e~ range from about 400 to 700 nm. In the pl~ d method of fia~licdtiol~ a~ d~ ;bc~, below, the SUb_~alCS 26 and 36 are also transparent toulllnvi~let (UV) light in the range from about 250 to about 400 nm. This range 25 allows the microco,l~ ol~, and microlenses to be formed by pholopol~lllc.~lion of reactivc ,..~ P ~ cd by W light. The index of refraction of all three S~:i~alC,S are equal or sub ~ 9lly equal and may range from about 1.45 to about 1.65. The most ylcf~ ,d index of refraction is from about l.S0 to about 1.60.
Sub ~alc,s 21, 26 and 36 may be made from any ll~l pdrc.lt solid Illdte.i&l.
30 P~f~,.led ",~r~ lc include llans~,are.ll polymers, ghss and fused silica. Desired characten~tics ofthese m~tPrislc include ...ech~l~ r~l and optical stability at typical opc alion tc-ll~ -alures ofthe device. Most pl~;r~ ,d mstprisl~ are glass, acrylic, polycalborldtc and polyester. Substrates 26 and 36 also seive as spacers ~el~ ,en the miclocoll~ Q.~ 30 and mie.olcnses 40. The co~ ed thickness of .,~.,lla~c5 26 and 36 is G~,1; .. ; ~ to cause light from microcoll;.. -~ol.,30 to be co!lim~ted by 217~37~

microlenses 40 Microcollim~tor 30 and microlens 40 can be constructed from any l,~.sl,arenl solid polymer material ~l~f~.lcd mstçriqlC have an index of reLa~;l;on s~Jba~ ly equal to aubs.la~es 21, 26 and 36 of bel~, __ n about 1 45 and about5 1.65 and include pol~",~ yll",ll,a~ylate, polyc&l,ùndte, polyester, polyal,y.~,ne and polymers formed by pho~opoly...c. ;,~, ;nn of acrylate ~. nno.. ~ra More p-~,f,.l~d m~teri~lc have an index of refraction b_h._~ abut 1.50 and about 1.60and include polymers fo~med by photopoly",~.~alion of acrylate ...nno.... r mixtures cQ~.pGsed of u~ e acrylates and methac,yldlcs, ester acrylates and 0 methac,ylales, epoxy acrylates and .. ~ll.7i~ylstes, (poly) ell,;l~.ne glycol acrylates and methaaylates and vinyl c~ e organic n ~on~ Useful ",onG",cls include methly methacrylate, n-butyl acrylate, 2 ell,ylh_A~I acrylate, isode~
~ lale, 2-h~dlu~_lL~1 acrylate, 2-L~dl(JA~IJl'Upyl acrylate, ~cloL~I acrylate, 1,4-b~ e~ l diacrylate, clllO~ylalcd b;~l. hf n-)l A diacrylate, neop~.lt~lglycol 15 diacrylate, d..lh;lene~col diacrylate, diethylene glycol dimethacrylate, 1,6-I;ol diacrylate, ~iu..~lol prop~e triacrylate, penta~ Lilol triacrylate andpenta, ~}uilol tetra-acrylate. F-spe~slly useful are llUAlUI~ ~hcrei~ at least one C~ r is a ml~ll;r ~ l;or~ n(s~ such as diacrylate or triacrylate, as these will produce a n~,lwoll~ of crosslinks within the reacted photopolymer. The most20 p-~f~ d mstçrislQ for use in the method ofthe iu.~e.ltion are crosslinked polymers formed by pho~opol~...~,; ;-.~ ll iAlur~s of ~lhuA~laled b~ k~ol A diacrylate and llL~lhylol propane triacrylate. The index of re~action ofthe most pr~f~ d material ranges from about 1.53 to about 1.56.
The indeA of refraction of int~,.a~ilial region 35 bel-.~n the rnicrocollims~tors 25 30 must be less than the index of refraction of each microc~ Qr 30. ~I.,fc;ll~d rnaterials for iult~.atilial regions include air, with an index of refraction of 1.00 and fiuolopol),...e ~e -'- with an index of refraction r. nging from about 1.30 to about 1.40. The most pref~ d material is air.
The adhesion prol...~ti,.g layers 28 and 38 shown in Fig. 2A are an organic 30 --~ l that is lig~ht llAI~ -- C~ , and that causes microcollimators 30 and microlenses 40, espec~slly those formed from polymers, as for example photocroisLIked acrylate .. ~ , materials, to adhere al.ul~l~ to their ~speeli~/e s~allale. Such ~ e- ;~lc are well known to those sl~lled in the art . The Ih- ~ ..ess of adhesion proll,oting layers 28 and 38 is not critical and can va~y widely. In the 35 p,efe.,~d P~.~bo~ ofthe invcnlion, adhesion layers 28 and 38 are less than 2175~71 about 1 IlliCIo~ .t~ thick.
Figure 2B shows another embodiment of the present invention in which the rl.n~ l;Gn of the aperturing means 8 shown in Fig. 2A is c~i -.l ;n~ with the first co!l;n.~ B means 10. In Fig. 2B the sides 33 of microcoll;...~'G,~ 30 are coated5 with a l c ne~ . layer to form a lll"luled surface. The hput ends 32 remain .pa,~ t to accept the light rays and becGl.~e the input apc.lur~s for the "~.crocolli-nstor array. The coathg used 0.1 the sides 33 ofthe microcollimatorscan be any reflective material such as l~lminl~m chrome or silver.
Figure 3A shows a cross secl;on~l view ofthe ap~.lu,ing means 8 CollllJlis~ s~lb~llaLe 21, reflective regions 24 and transparent aperture regions 22.
In this illu~ ~ion, the dp~.lul~ regions 22 are &.,~ngF;d h a square or recl;...~,.ls-r array, as shown in Fig. 3B, ~lthnugh other &I;--~g.'r ~fnl~ such as a k .~on~l pattern are possible, as shown in Fig. 3C. The aphlu,~ regions 22 may be any shape such as a re~le or circle as shown h Figs. 3B ant 3C having length A;.. ~n~ 42, a width A ."FI, :or~ 44 or a A:~ t~r S0 re~e~ rely. It is p~efel,ed that the sum of the areas for all light apcllu~s 22 range from about 5 percent to about 50 percent ofthe total area of;,ul,sl.a~e 21. It is more pre~ ;d that the sum ofthe areas for all light apcllun s 22 range from about 10 percent to about 40 percent of the total area of S~b~llale 21. It is most p,~f~ d that the sum of the areas for all light ap~ .lures 22 range from about 20 percent to about 30 percent of the total area of s~ale 21. D;.-.~Q:onQ- 42, 44 and 50 are a~ Qted to meet thosep&~"et~
The a~.~ regions 22 have repeat AiQt~n~s 46 and 48 in Fig. 3B and S2 and S4 in Fig. 3C. The repeat A;~l. nccs 46, 48, S2 and S4 may be equal or ~mPq~and may vary widely dcrp~ .A;.~g on the l~s~ tion and AimPn~;on~ ofthe display.
Desired values ofthe repeat d;~l; c~s range from about 10 microns to about 40 millimeters. More prl f~.l. d values of the repeat distances range from about S0microns to about 10 mill;...~ t~ ~. Most pr~f~ d values of the repeat A;~nre~
range from about 100 microns to about 2 ",:11;" t~ ~. Fig. 3D illustrates another ~ ,e shape ofthe ap~.lul~s 22. Each apc~lu.~ 22 may have a length S6 that t~ ially cGl, -.~û~ c to the length of s~lb ~ale 21, width A ..~ 58 and repeat dimension 60. Width 58 and repeat A;..~ 60 cG-l~sl)ond to those stated above for Figs. 3B and 3C.
A single micr~.coll;-..~,~or 30 is shown in Fig. 4. A cross s~lion of the 35 ~ ùco~ tor 30 in a plane parallel to the input surface 32 and the output surface 34 can be any shape such as a square, .ccl~ngle or circle among others. It is pr-,f.,.l~d that the shape of each ofthe input surfaces 32 is s~b~ y the same shape as its co~ . ~3por,dil~ apc. lul e 22. Accord~gl.~, it is also p-ef~ d that the total area of the light input surfaces 32 is sub~ y equal to the total area of 5 apertures 22 ~iccussed above.
Light input surface 32 has a width d;~..Pn~:ol- 68 and a length d;...r~.~;o~ 69 (not shown). Alternatively"~ .cion 68 may ,epn,se.~ .... t~ r 50 if the shape ofinput surface 32 is circular. It is p-~f~ ,d that width ~;.. Q:~n 68 is s~l,st;~ lly equal to the coll~onr~ g width .I;.,,~P~,- on of ap~.lure 22. It is pl~,f~ d that 10 length ~ - :o~- 69 be ,~,b-,t~ ;A1ly equal to the co,le.~o~ g length ~ Q '~n of apc.lul~ 22.
Light output surface 34 has a width ~ ;nr, 72 and a length ~ on 73 (not shown). ~ .,ly, dimension 72 may lcpre3c.l~ the ~ U~t~ r of a circle ifthe shape of output surface 32 is circular. ~Idth 72 may vary widely ~epe~ g on 15 the di ~ r,~:ol s and reso'-ltion ofthe display. That is, smaller disl,la~s, such as laptop colllyul~r ~ and avionics di..~,la~D would have greatly reduced dimensions versus larger d;syl~, such as large-screen, ~at-panel televisions. It is yief~ d that the sum ofthe areas for all light output surfaces 34 range from about 40 percent to about 100 percent ofthe total area of S~:lb3t~te 26. It is more pl~,f~ d that the sum ofthe areas for all light output surfaces 34 range ~om about 55 percent to about lO0 percent ofthe total area of s.~ ale 26. It is most yi~,f~ ,d that the sum ofthe areas for all light output s~ es 34 range from about 70 percent to about 100 percent ofthe total area of ~ dte 26. Dimensions 72 and 73 are adjusted to meet those pa-~n~,t~
The height of ll~clo~~ or 30 has dimension 70. Desired values of the dimension 70 range from about 0.3 times width 72 to about 6.0 times width 72.
More pr~f~ d values of the dimension 70 range from about 0.4 times width 72 to about 4.0 times width 72. Most p.efe..~ values of ~1;.... I -;on 70 range from about 0.5 times width 72 to about 3.0 times width 72.
Sidewalls 33 CQI~ input surface 32 to output surface 34. Sidewalls 33 can be straight, but preferably, sidewalls curve Oulw&~ as shown in Fig. 4.
A pc~.~pe~ ., view of an array of l...~,locQ1l: n~G, ~ 30 cGll.,~,onding to an array of apc~ s 22 is shown in Figs. SA, 5B and SC. The figures illustrate possil~l~ cQnfi~rations of a single microcollimator 30 and possible ;~ g~ ~."-~ of 35 an array of mielocQ11~ o.~ 30.

wo 95/14255 Pcr/uss4/1lss4 The second coll; .~I;n~ means 12 co,l,~,ises an array of n,iclGlel~ses 40 The rnicrolenses 40 are preferably made from the same ono~f ~ as those previously disclosed for the microcoll;.. -lo,~ 30 and have a index of refraction equal to or s~ ly equal to the index of refraction ofthe microcoll;.. ~lG,~ 30 5 However, any II~UISIJdre~I1. material may be used, as for example, those materials previously di~lcced A single microlens 40 is shown in Fig 6 The microlens 40 can be either a spheric~l lens or an ~ph jc~l lens The dimension 80 lcp.e~.l~s the flat light input surface of microlens 40 and can vary from about 10 microns to 40 mill;----,t~
10 More pr~fe ,~,d values ofthe d; . ~ ;on 80 range from about 50 microns to about 10 mill;-.. Ie. ~. Most pref~ d values of the dimension 80 can range from about 100 microns to about 2 mill;....,t~ ~ The desired values of height 82 range fromabout 0 05 times the dimension 80 to about 4 0 times the dimension 80 More pref~ ,d values for the height 82 range from about 0 08 times the dimension 80 to about 3 0 times the dimension 80 Most p,~,f. .l~d valucs for the height 82 rangefrom about 0 10 times the dimension 80 to about 2 0 times the ~ ;OI- 80 If microlens 40 is a s~,l~.ical lens, the lens will have one curved output light surface having a radius of cu. ~alulc 84 The radius of .,u, ~tu,~, can vary ~,videly depending on the repeat ~ es 46 and 48 or 52 and 54 of the corresl,or,L.~
2 0 microcollimator array. ~.,f~,.,.,d values for the radius of curvature range from about 5 microns to about 20 m;ll:~. et~ ~. More pref~ d values for the radius ofcul~ralul~ 84 range from about 25 microns to about 5 millimeters Most pr~,f~ .;dvalues for the radius of curvature 84 range from about 50 microns to about 1 millimeter In order that microlens 40 collect ;,~ ially all oftne light dh~,~,lcd 25 out of microcollimator 30, the f-number of microlens 40 should be l.,lhti~.,ly small The f-number values for microlens 40 can range from about 0 5 to about 4 0 More f.,..~d valucs for the f-number range from about 0 6 to about 3 0 Most p,.,f,_.,~ values for the f-number range from about 0 7 to about 2 0 A pe.~.e~ , view of an array of microlenses 40 corres~ndi.~ to the array 3 o of a~. lu,~s 22 shown in Figs 3B, 3C and 3D is shown in Figs. 7A, 7B and 7Cre "e~ ly. Accoi..li,.gl~, the array of microlenses would have the same repeat r~s as those of the array of ~c. lu~ .,s 22 An exploded p~ ,e~,ti./e view of co,.~*,onding " icr~co~ or arrays and microlens arrays is shown in Figs 8A, 8B and 8C For evely aperture 22 there 35 exists a co"espol,ding miaccollimqtor 30 and a ~"W~,Ol ting microlens 40 that W095tl4255 PCT/US94/11894 aligns with the output surface 34 of each microco11imqtor 30. In operation, the sub~lalll,ally col1imqtPd light rays ~ n-~; ~e from the ll.icloco~ ol~ 30 are further co!~ q-ted by the mi-,-olu-3f s 40 to provide a more subs~ l; 11y collimq-ted light source for mod11lqting means 16.
An alternate embodiment ofthe invention is shown in Figs. 9, 10A, lOB and lOC. In this c~..bo~ the first cQ!I;...~ p means cc~n~ es a planar slab of ll ~t~a~ e nl material 70. An array of microlenses 40 are qtt~^hPd to the planar slab 70. Divergent light rays l.~n;...,it through s~ le 21 via refraction and travel through planar slab 70 ~r~or l...~, to Snell's Law. The rays then enter microlenses 10 40 and l-~ns..ul through the microlenses 40 via refraction and emerge from the microlenses 40 as a ~ fl~lly col1imq~ted light source for the m~ h~ means 16. Slab wav~ ,uide 70 preferably has the same chara~t.,.i~ ,s of S~bSll alf S 21 and 36 as earlier dc ~ . il,ed The ~h ,~ ~.f~ 5~ of slab v~a~u;de 70 is o~t;~..; f~ to cause the light rays refracted lll~,lll.~ugh to be co11im~ted by microlenses 40.
Figs. lOA, lOB and lOC illustrate possible co~lf~ alions ofthe array of microlenses 40 attached on the surface of slab ~a~,guide 70. As previously ~d, a single microlens 40 cGll~,ldtes with a single aphlure 22.
A further c.-ll,odi,-.~ t of the present i,.~.,.ltion is shown in Fig. 11. the baclclight ~semhly coll~Jlises a light con.,e.ltldth~g means in ~l~ n~l;Qn with an 20 array of microlenses 40. The light concf ~ ting means is p~.f~,.ably an array of microcQI~r~ alO~S 90. Mi.i.~,conc~ to,~ 90 are tapered optical c~
attached to a planar substrate 92 via adhesion pr~,...~t; ~8 layer 94 and havingl.~.~.od s;d~,~.o1l~ 98, a planar light input surface 96 adjacent to the s~-~a~e~ and a planar output ent 100 distal from and parallel to the light input surface 96, 25 ..h.,.~. the area ofthe light output surface 100 is smaller than the area of the light input ~face 96. Unro~ ed light rays from the light source 6 pass through the array of mi~,~uconf~nl~alol~ 90 via one or more r~fle~ionc from the .~I~-orfd sidewalls 98. The tapered construction conr,~lt~dtes the light rays so that the output of each ",.~.r~col-r.. ~ ~ alor 90 beco,l,es a source of light that is ~ nl ;~lly - 3 0 smaller in area than the area of the light input surface 96. The output of the mic~ocol-r,~ alO, ~ 90 is directed to a coll e,~o~ array of microlenses 40 d;~osed above the micloconc~ lalors 90 at the app,oy,idte d;~t~nce The light is through each nicrolens 40 via refraction and c."~ es from the microlenses as a s~,;,t~ lfl~lly collirnqted light source for the mod-~l9ti~ means 16.
Asingle,~ucluconr~ a~or9oisshowninFig. 12. Its~ nn~;ons 102, 104 W O 95/14255 PC~r~US94/11894 and 106 are the same as dimensions 72, 70 and ~68, l-,~e~ ,ly, ~ierlosed above for a microcollimator 30.
Figs 13A-13C and 14A-14C further illu~l~ale the possible ~l~ ~g.r, l~r~ of an array of microcol~çe .1~ alUI ~ with a CG.l~ ,onding array of microlenses 40.Arrays of l~ icr~co~ lo.~ 30, micluconce.ltlalol~ 90 and microlenses 40 can be manufactured by a variety of techniques inrluAi~ injection molAing, cclllp~i.;,;on molding, hot roller pre~,g casting, pho~opol~"~e.~lion within a mold and pho~opol~...e ;~ l ;QI- processes which do not employ a mold. A preÇ~l-ed technique is the pho~opol~ ion process as ~ --losed and ilh~ ted in the 10 ~Ol~-~.- .n;ol ed U.S. patent ~p~liCnl;~ col~Jolaled by n,f.,.cnce. Some simple ,~o~l;f.~ 5l;o.~C to that process are shown in Figs. 15A and 15B.
Figure 15A illu;~llales a yholupol~ nproce5s to produce mic.ocoLllators 30 of the type shown in Figures 1, 2,4 and 5 and microcQnc~ ~t~a101590 of Figs. 11-14. A photc~ 108iS placedin ~ h n;l~l 5 contact with a ;.ul~ te 26 having an adhesion layer 28 .hc~ the pholQ,.~c~ has opaque and transparent regions. A sub~ )r unifo~n thickness of pho~opolymerizable IIlI~lUl~, 114 cûlllplislll~ ...ono.~ ~ and a photo;~ or is placed ,n ~slla~e 26 with adhesion layer 28 and backing plate 110 with release layer 112. In order to form microco!l or~ or miclo.~ dtors, the 20 photc.;~.it;~tor must be present in a s ~ 1 amount to absorb a cigr ifi~snt fraction ofthe ultraviolet light within the pho~opolymerizable l~lule layer. A light diffilser 116isplaced ~h.C ~ the ph~C~"~rl 108 andthesourceof ~ a~ 'etlight 118 which causes thc ~lh~ ~!et light to be spread over a range of angles. In order that the type of microcoll; . -~o. ~ 30 and micloconc~.1 ~ ators 90 be formed, the diffuser 25 should spread the light over a full angle (measured at the 50% ~lt~ points) of appro~ rl~ lS 15 degrees. The photopol~..lc~ble IIU~ , 114 is e,.posed to ullla~,;clet light I 18 IIUOUgh diffuser 116 and through the transparent regions ofthe phOtQ..~q~l 108 for a tirne and under con~ ;nn~ s~ n1 to photopol~ll..,.
regions ofthe ~fin~ ~ mixture to form an array of miaoco~ G,~ or 3 0 miwoconc~ dtûl After c.~l,ûs~ to ultraviolet light, phot~ll ssk 108,baeL;.~f~
plate 110 with rdease layer 112 and the lln -l~os~ photopol~ .~ble mixture 114 are [e.no~cd leaving an array of lluClOCQ~ a~Ol~ or miaoc~ ors attached by a~hPsj~n layer 28 to i,~t,dte 26.
Figure 15B illustrates a process for mahng miaolenses 40 ofthe type 35 illustrated throu~h~ut This process is similar to the process illL~a~ed in Fig. 15A.

WO 95/14255 2 1 7 53 7 1 Pcr/uS94/11894 -In order to form microlenses, the photoi~liator must be present in a sufflcient amount to absorb a s~ fiCvnt fraction of the ultraviolet light within the photopoly,.,~.-~able ~ urt layer. A light diffuser 116 is placed b~,h.ecn the phntomsQL 108 and the source of ultraviolet light 11 8 which causes the ultraviolet 5 light to be spread over a range of . ngles. In order that the type of microlenses 40 as shown be formed, the diffuser should spread the light over a full angle (measured at the 50% illten~ y points) of applu~ ely 45-120 degrees. The photopolymerizable mixture 114 is e,~l,osed to ultraviolet light 118 through diffuser 116 and through the t.ar.i.~ regions ofthe photo., ask 108 for a time and under 10 co~;l;ons s-~n'c;~ to pholopoly",~ e regions ofthe ...--n~ I-~lul~ to form an array of microlenses 40. The ultraviolet light is turned offbefore the phntopoly...~ region touches the release layer 112. By controlling the angular spread of light passing through diffuser 116 and by controlling the thickness ofthe s~ -~ale layer 36, either sphP,nc~l microlenKs or asphe.i.,al microlenses can beformed.
This invention can be used for those app~ l ;onC for which bac~ htinE is rc~luir~. Illustrative of such app!~ ;on~ are computer terminals, tel~ ~;s;ons, aircrat cockpit displays, alulG".oti~e i~ u~ t panels and other devices that provide text, graphics or video i~lfu~ alion.
The rollu~.illQ specific examples are pre~.lted to pa.li-,ul~ly illustrate the invention and should not be construed to place l~ l;on~ thereon.

An array oftapered optical ele " .~1~ with center-to-center SpS~ of û.OSO" was formed on 0.004" thick pol~e~t~l film using the pholG~.~pGs.lle setupillu~aled in Fig. 15A. The photo!;ll.o~r~phically created glass mask (5N X 5") with 0.025" x 0.025" square dear regions a.,.u~6od in a square pattern and scp&d ed by 0.025N black lines that were opaque to IllL.aviclet and visible radiation was used.
The center-to-center ~ ce bel~.~cn adjacent open squares on the photo".ask was 3 0 0.050~. Onto this mask a few drops of ~ ol wae applied and then a 0.0065"
thick poly(ethylene ta~ Ate) (PET) film spaca film was pressed on. Onto the spaca film a few more drops of met~no~ were applied and then a 0.004" thick PET
~u~ ale film was pressed on. This substrate film was prepared with an ultra-thinfilm surface treatment which rendered it reactive and adherable to pol~t...~.~ g3 5 ~ n-~-~ S c'-~ti~nC Such surface-activated films were known to those skilled in the WO g5/14255 PCT/US94/11894 21~5371 art. The surface tension of the ....,lh~-ol caused the two films to mildly, but firmly adhere to the mask. The mask spacer film and the surface ;lctivated PET substrate film cor.~ ed the array substrate ~lbacs- ~hly.
Onto a se~,&ale 5"x5"x0. 125" blank glass plate a few drops of ... Ih~nol 5 were applied and then a 0.004" thick PET film was pressed on and held in position by surface tension. This cor. ~ led the release film sul~se ..hly. The release film ~.ibq~s~ .~bly was placed film-side up on a black metal phlrullll co.~ ;ng threaded holes. Glass spacers 0.050" thick were placed around the edges ofthe release filrn s.~b~sf .~hly. Appro~ ,ly ten millilitçrs of a liquid photopol~ e. ~clF rnixture0 were pil~elled onto the center ofthe release film. The photopolymerizable mixture con :;,ted of dpplu ; ~,n Iy 63% ethoxylated bic~ k~ol A diacrylate, 31%
h~lolpropane triacrylate; 2% a,a-dill.~,ll,~loxy-a-h~dro~ ?C~ ~npht ~ -e (I)arocur 1173) photQ; ~ IOr, 2% b~ lh~l ketal (Irgacure 651) photo:~ tQr and 2% of a ~ ure of 1 part l-ll~dioA~.,loheAyl phenyl ketone and 1 part 5 be.~oph~ol~e (Irgacure 500) photQ;-.;t;-~or. The total p~ .,enlage of pholo;~ ol~ was 6%. The array ;,ul,~lale as~n~l~ (photo~ r~ /spacer/substrate) was placed, PET ~,~.,llale side down, on top of the photopolymen2 able mixture. A
clear 5" x 5" x 0.25" thick glass plate was placed on top ofthis entire fabrication ass~ and metal clamps and screws were used to fully and evenly col"press the 20 plates t~g~the~ r~s~lting in a 0.050" thick pho~opolymelizable layer h,h._~,n the backing plate and the substrate po~ el' film.
In order to form the array of tapered optical e~ s, the entire fabrication q~se .l~ly was placed under the collimating lens of an ultraviolet (UV) radiation e - l'- ~ e system. A light .1;11~ n sheet of tr-qr~ cf~t plastic film was placed 25 be.- ~. the phs~ and the cQ~ d lens ofthe W radiation e ~O~ lt system which caused the ultraviolet light to be spread over a range of angles. In order to form tapered optical el~ , the diffuser was chosen so that the light spread over a full angle (measured at the 50% illtena;~y points) of applo~ ly 20degrees. The fabricqtio~l as~.l~ r was irradiated with W light for 80 seconds.
3 0 The ~ab. ;c~ n as~..lbly was then rl ~5 ~5- ..hle d and the film with the array of tapered optical e~ now formed, but still covered with unl~cted pho~opolylll.,. _~'e mqtf~risl in the inlc.~lili~l regions b~,t .~ the tapered optical el~ , was placed in a stirred bath of isoplupanol and left for ten m;-nltes After removal of the r~,i;dual ..I-nr~ ,., the tapered optical el~ .f~ were dried in a 3 5 stream of llilloge.~ gas, placed in a lul~ogen gas-purged f n~loJ~e with a qu~tz -~ 2175373 window, and hard cured under the UV radiation for an additional 20 sceonds.
Optical llu.,loscol,y was used to evaluate the tapered optical ~4 ,~r .l~ The cros se~!l;ol~al shape ofthe individual tapered optical c~ .ni was ap~ro~ y square with dimensions of app,~ Ply 0.040" x 0.040" for the ends ofthe S tapered optical cl~ n~s ~ Pnt to the ~sllale (output ends). The ends ofthe tapaed optical P.~ e--t~ distal to the substrate (input ends) had f~ nC of appro,;...~lcly 0.020" x 0.020". The height ofthe tapered optical ele ..- ns wasappro~ ely 0.050".

EXAMPLE n In order to deposit a reflective ~ .... coating on the sidewalls of the array oftapered optical e~ of Example L the array was placed, ;~ a~e side down, into a vacuum e~a~ lor. Appro~ y 1 micron of ~ . . was e~apolalcd onto the tapered optical ele .. ~ The evaporated ~ .. ; .. ~ coated the 5 sides ofthe tapered optical el~ ..e~ and the ends ofthe tapered optical el~ -,a distal to the s~ ,l,ale. The ~ coated array was lhl-O~ from the w~lalor. The ~ min~m coating on the ends of the tapered optical Pl~
distal to the s~ ~ale was r~,."o~ed by poliching the ends ofthe optical Pl~ ts first with poli~h~ paper coated with lS micron grit followed by polisl,..,g with20 paper coated with 3 micron and then 0.3 micron grit. The ~ ;"~ array oftapered optical ~ol~"- ~1~ with ~ mimlm coated sidewalls can be used as either an array of mi~"ocoll;~ o.~ by using the 0.020N x 0.020" ends ofthe optical flP ~.r~t~ as the light input ends and the 0.040" x 0.040" ends ofthe optical ~I .,,~.,lc as the light output ends or as an array of microcol-cf ~t.alol~ by using the 0.040" x 0.040" ends 2s ofthe optical ol .. P-~t~ as the light input ends and the 0.020" x 0.020" ends ofthe optical Pl "P ~tS as the light output ents.

EXAMPLE m An array of ,...~,lo!en~Ps with center-to-center spacings of 0.050" was - 3 0 formed on 0.004" thick polyester film using the photG~ G~ re setup illustlaled in Fig. 15B. The photc~l:lh()graphically created glass mask (5" x 5") with 0.025" x- 0.025" square clear regions a~ 3ed in a square pattem and Sep~al~i by 0.025"
black lines that were opaque to ultraviolet and visible radiation was used. The center-to-center d~ nce b~ .3en ~dj~.ce~l open squares on the pholo",ask was 0.050". Onto this mask a few drops of "-- Ih~nol were applied and then a 0.0l3"

2175~71 thick poly(ethylene tereph1h~l~te) (PET) filrn spacer film was pressed on. Onto the spacer film a few more drops of ...~ nol were -applied and then a 0.004" thick PET
~bsllale f~n was pressed on. This substrate film was plepared with an ultra-thinfilm surface ~ t~n ~1 which rc~ d it reactive and adlle. b'e to poly.. ;~;ng 5 ~ n~ r SQllltion-c Such surface-activated films were known to those skilled in the art. The surface tension ofthe .~ h-nol caused the two films to mildly, but firmly adhere to the mask. The mask spacer film and the s.l.racc activated PET substrate filrn cor.~;l.,lcd the array substrate s~b~s~ bl~.
Onto a s~,p~ale 5"x5"x0. 125" blank glass plate a few drops of .... Ih~nol 10 were applied and then a 0.004" thick PET film was pressed on and held in position by surface tension. This con ~ le~ the release film ~ b~csf "hly. The release film s~b~s- ..bly was placed filrn-side up on a black metal p~-~ru.... co..1; in;t~g Ihrczded holes. Glass spacers 0.050" thick were placed around the edges ofthe release film s~ cs- ...1-ly. Appro~ ten rn~ itGrs of a liquid photopGl)~."~.~able mixture15 were p;l~c~led onto the center ofthe release film. The photopolymerizable mixture c~n :~ted of app.u~ 63% ell.uA;laled b ~.hf -ol A diacrylate, 31%
Il.,.,e~ lolp.ul,dne triacrylate; 2% a,a-di.ll~,~loAy-a~ LùAy acetGphenone (Darocur l 173) ph~toin~ or~ 2% ben7i~ lh~l ketal (Irgacure 65 l) photoinitiatorand 2% of a llUA~ of 1 part l-l~ oA~,c~eloh~,A~l phenyl ketone and l part 2 o benLoph~ nr, (Irgacure 500) pho~oi~t~tor. The total pc~.lt~ge of pholo;n;1; tGl~ was 6%. The array substrate A~se .~ r (photo~ool /~)acer/substrate) was placed, PET s~e side down, on top of the ph~-~opol),lll_.~ble mixture. A
clear S" x 5" x 0.25" thick glass plate was placed on top ofthis entire fahricatiQn oc~ ly and metal clamps and screws were used to fully and evenly col.ll,iess the25 plates toa. Ih- ~ ie3 ~; .9 in a 0.050" thick photopolymenzable layer hCt-._en the backing plate and the s.~Dl-ale polyester film.
In order to form the microlens array, the entire fa~.ic~l;on A~gc .~hly was placed under the collimating lens of an ultraviolet (UV) radiation eA~cjs~e system.
A light A;fl;~Q;ng sheet of translucent plastic fflm was placed h~l~. ~n the p hol 3 o and the co~ lcJ lens of the W rr~lis~ior ~ G~ e system which caused the ultraviolet light to be spread over a range of angles. In order to fonn microlenses, the diffuser was chosen so that the light spread over a full angle (..leaD.lled at the 50% i,l~ells;l~ points) of applù~ ly 90 degrees. The fabrication ass_lllbly was *adiated with W light for 30 seconds. The area of photopoly,..~ ;nn did not 35 come in contact with the release film. The fal,li~d~ion AC~ was then wo 95/14255 PCrJus94/ll8s4 217~37~

~i~cc~ ."hled and the film with the array of microlenses now formed, but still covered with ~ ed pholopol~ .kable material in the illL~ lial regions - between the microlenses, was placed in a stirred bath of isopropallol and left for ten min-~teS After removal of the residual "~onGI~.~ r, the microlenses were dried in a 5 stream of nil,ogen gas, placed in a nlllogen gas-purged ~n~-los .1 e with a quartz window, and hard cured under the W r~iqtiC.rl for an rdrlitiorql 20 s~conAc Optical lluCIOCOlJ~ was used to evaluate the microlenses. The lenses were &ppro~ otely round with a ~ ,tl ~ of 0.050". The height ofthe lenses was &~p~ ly 0.025".

EXAMPLE IV
Acsll;.,,c~ plightz~s~ wascor...~u.,lcdinthe &1~ 1 of Fig.2B
using the array of ~ql---..;-.---.. coated microcollimators of Example II and the array of rnicrolenses of Exampk m. A s~ e ~u0~ t larnp with an input power of 15 aplJl`O; ~ Cl~ 30 Watts was used as the light source. The surface l.. :n~nce of the fiuorwc~.lt lamp itselfwas .ll~s.lr~ to be 3000 foot-l&ll~h~. The array of al~ n; ~ microc~ll;...-~o,~ was placed a J;~l_nr~ of ap~"o-;.~ ely 0.25" from the plane ofthe s_.~ ~ille nuOI~SC~ lamp. The small pc~lc~h~ ends ofthe miclocoLIlators were facing the lamp. The array of microlenses was placed 2 o a~jacent to the array of microcoll; tto, ~ and aligned so that flat input surface of each miaolens was aligned with an output surface of the miaocollimator. Spacer films of PET werc placed ~ the output side ofthc micorcollirnator array and the input side of ~e microlens array to adjust the spacing b~,h.C~'~ the miaolenses and micr~cr.~ ators. The best results oc~iul~,d when the total spacing b~l-.~n the 25 miclocolLIlators and the miaolenses was appro. ;-.. ~ 0.0S0". The output light fiom the collima~ng light -ss~ ,~hly had an angular spread of ~pr~ ly +20 L~ fiom a d;~c~.liûn P~ n.l;. .~l~r to the plane ofthe assembly. At the center ofthe output light ~ b~JI;on the 1.. ~ ofthe csI~ light asse.. lbly was ~plu~ trIy 3000 foot-l&llb."Ls.
EXAMPLE V
A co~ light asscmbly was cor.. llu.,led in the a~ î of Fig. 9 using an ~ n.~... coated mask as an array of ~c.lules and the array of microlenses of Example m. The ~ ";.,~ n coated mask had 0.025" x 0.025"
3 5 square clear regions &l~u~g~d in a square pattern and sep~aled by 0.025" black WO95/14255 Pcrluss4/1lss4 Z1~53~ 1 -20-lines that were opaque to visible radiation. The center-to-center ~ nçe be~ ,en a~j~cçnt open squares on the photomask was 0.050'i. A s~ ,c~ltine ~uon,sc~ t lamp with an input power of app,u~ a~ly 30 Watts was used as the light source. The surface l~ nce ofthe fluolesce.lt lamp itselfwas measured to be 3000 foot-5 la.nl~ . The ~ minl~m coated mask was placed a ~ n~e of appro~ ely 0.25"from the plane of the 3_ I,e.,l;ne fluGlwce~ll lamp. The array of microlenses was placed n~j~ cent to the mask and aligned so that flat input surface of each microlens was aligned with an open square ap~,. lur, in the mask. Spacer films of PET wereplaced ~eh.~ the mask and the input side ofthe microlens a~ay to adjust the 10 spacing h"h. ~en the microlenses and the mask. The best results occured when the total spacing b~ ,., the microlenses and the mask was a~Jp,u~ ly 0.050". The output light from the CQ~ ;~ light ~cs~ ..hly had an angular spread of ~p,~, ;. "~1 ly i20 I,.es~.l~d from a du~liun pc.~.nA: ~-lq- to the plane of the bly. At the centa ofthe output light ~ n the 1~ ofthe 15 coll~ light ~c .~hly was approAulldlely 3000 foot-L,Ibc~.~.

EXAMPLE VI
A collimating light ~s~ hl~ was constructed in the ~1~ of Fig. 1 1 using the a~ay of q-l--- .;..---.. coated micr~conr~nl~al~l~ of Example II and the array 20 of microlenses of Example m. A ~.~,c~lti"e JluG~scc~l lamp with an input power of al,~ç~ ly 30 Watts was used as the light source. The surface ll....;n~nr,e ofthe fluo,e3~.lt lamp itselfwa~ ",~uo~ to be 3000 foot-lamberts. The array of n~ d microcollimators was placed a ~ c~ of apprc, ;~ f Iy 0.25" from the plane ofthe ~.~,e.ltu~ fluore~ellt lamp. The array of mi~rocQnc~ atOI~ was 25 o,;~te;l so that the large ends ofthe mic.uc~c~ û,~ were facing the lamp. ThealTay of miaolenses was placed adjacent to the array of miclucQn~ alGI~ and aligned so that flat input surface of each microlens was aligned with an output surface ofthe miaocon~-e ~l~alor~ Spacer films of PET were placed b~,h.~,en the output side ofthe miclocQn~ alor array and the input side ofthe microlens array 3 0 to adjust the spacing ~,h. _~ the miaolenses and microcQn~ alGI~. The best results occured when the total spacing bel~ n the milroconr~ aLûl~ and the microlenses was appr~ nly 0.050". The output light from the coll;...-l;np light a~ bl~ had an angular spread of app,oAunately +~0 ",ca~. red from a direelion p~.~cn~ c ~ to the plane ofthe ~cs~ hl~. At the center ofthe output light 35 d;stlil,.llion, the l~....;.~nce ofthe coll;...~ g light a~ hl~ was app,o ;~. ~t~ly wo 95114255 Pcr/usg4/118s4 217S37~

3000 foot-la,l,be.ls It will be understood that the particular e.,.bo~;~nenl~ desc.il,ed above are only illustrative of the principles of the present invention, and that various 5 .~lo~ c~;Qns could be made by those skilled in the art without delJ&Ii.-g from the scope and spirit of the present invention, which is limited only by the claims that follow.

Claims (10)

What is claimed is:

1. A backlight assembly for use in an electo-optical display, said display having a modulating means capable of providing an image to a remotely positioned observer, and said backlight assembly comprising:
(a) a light generating means;
(b) an aperturing means operatively disposed in close proximity between said light generating means and said modulating means;
(c) a first collimating means disposed between said aperturing means and said modulating means, said first collimating means having a planar light input surface in close proximity to said aperture means and a planar light output surface distal from and parallel to said light input surface and larger in surface area than said light input surface, wherein said light rays transmit through said first collimating means via total internal reflection and exit fromsaid light output surface in a substantially collimated pattern; and (d) a second collimating means disposed between said first collimating means and said modulating means and having a light input surface that accepts said substantially collimated light rays from said first collimating means and transmits the light rays via refraction and directs said light rays towards said modulating means in a substantially more collimated pattern.

2. The backlight assembly of claim 1 wherein said first collimating means comprises an array of tapered optical elements.

3. The backlight assembly of claim 1 wherein said second collimating means comprises an array of microlenses.

4. The backlight assembly of claim 1 wherein said aperturing means and said first collimating means comprise an array of tapered optical elements having reflective sides.

5. A backlight assembly for use in an electro-optical display comprising (a) a light generating means;
(b) a concentrating means having a planar light input surface in close proximity to said light generating means, a planar light output surface distal from and parallel to said light input surface and smaller in surface areathan said light input surface and mirrored sidewalls wherein said light rays enter through said light input surface and travel through said concentrating means via reflection and emerge from said light output surface as a more concentrated light source; and (c) a collimating means disposed in close proximity to said output surface and having a light input surface that accepts said concentrated light source from said concentrating means and transmits the light rays via refraction that emerge as a substantially collimated light source.

6. The backlight assembly of claim 5 wherein said concentrating means is an array of tapered optical elements.

7. the backlight assembly of claim 5 wherein said collimating means comprises an array of microlenses.

8. A backlight assembly for providing a substantially collimating light source comprising:
(a) a light generating means;
(b) an aperturing means operatively disposed in close proximity between said light generating means and said modulating means;
(c) an array of microcollimators disposed between said aperturing means, wherein each microcollimator comprises a planar light input surface in close proximity to said aperture means and a planar light output surface distal from and parallel to said light input surface and larger in surface area than said light input surface wherein said light rays first transmit through said aperturing means and then through said array of microcollimators via total internal reflection and exit from said light output surface in a substantially collimated pattern; and (d) an array of microlenses operatively disposed in close proximity to said array of microconcentrators and comprising a light input surface that accepts said substantially collimated light rays from said array of microcollimators wherein said light rays transmit through said array of microlenses via refraction and emerge as a substantially more collimated light source

9. The backlight assembly of claim 8 wherein said microcollimators and said microlenses are constructed from organic polymeric material and have an index of refraction of between about 1.45 and about 1.65.

10. A direct-view flat panel display comprising:
(a) a modulating means for modulating light from said light generating means to form an image visible to a remote observer;
(b) an image display means for displaying said image from said modulating means positioned adjacent to the light output surface of said modulating means, said display means comprising an array of tapered optical waveguides on a planar substrate, the tapered end of each of said waveguides extending outward from said substrate and having a light input surface adjacent said substrate and a light output surface distal from said light input surface;
(c) a backlight assembly comprising:
(i) a light generating means;
(ii) an aperturing means operatively disposed in close proximity between said light generating means and said modulating means;
(iii) an array of microcollimators disposed between said aperturing means and said modulating means, wherein each microcollimator comprises a planar light input surface in close proximity to said aperture means and a planar light output surface distal from and parallel to said light input surface and larger in surface area than said light input surface, wherein said light rays first transmit through said aperturing means and then through said array of microcollimators via total internal reflection and exit from said light output surface in a substantially collimated pattern; and (iv) an array of microlenses operatively disposed in close proximity between said array of microconcentrators and said modulating means and comprising a light input surface that accepts said substantially collimated light rays from said array of microcollimators, wherein said light rays transmit through said array of microlenses via refraction and emerge as a substantially more collimated light source for said modulating means