United States Patent [191
`Winston et a1.
`
`llllllllllllllIllllllllllllIlllllllllllllllllllllllllllllllllllllllllllllll
`
`US005303322A
`[11] Patent Number: \
`[45] Date of Patent:
`
`5,303,322
`Apr. 12, 1994
`
`[54] TAPERED MULTILAYER LUMINAIRE
`DEVICES
`
`I
`
`[75] Inventors: Roland Winston; Benjamin A.
`Jacobson, both of Chicago; Robert L.
`Holman, Naperville; Neil A. Gitkind,
`Chicago, all of 111_
`
`_
`[73] Asstgnee: NiOpties Corporation, Evanston, Ill.
`[211 App]. No’: 29,883
`
`4,649,462 3/ 1987 Dobrowolski et al. .............. .. 362/2
`4,706,173 11/1987 l-lamada et a1. ...... ..
`. 362/341
`
`4,729,068 3/ 1988 Ohe . . . . . . . . . . . . .
`
`. . . . . .. 362/31
`
`4,735,495 4/1988 Henkes .................. .. 362/310
`4,737,896 4/1988 Mochizulki et al.
`362/301
`4,747,223 5/1988 Bonds .......................... .. 40/219
`4,765,718 8/1988 Henkes
`..... .. 359/49
`4,799,050 1/ 1989 Princ et a1. .
`340/765
`4,799,137 1/1989 Abo . . . . . . . . . . . .
`. . . .. 362/309
`4,832,458 5/1989 Fergason ........................... .. 350/338
`
`[22] Filed;
`
`Mar, 11, 1993
`
`(List continued on next page.)
`
`’ [63]
`
`[56]
`
`,
`
`,
`
`Related US. Application Data
`Continuation-impart of Ser- No. 855,838, Mar- 23,
`1992’ Pat‘ N°~ 5'237’641-
`[51] Int. c1.5 .............................................. .. 0028 6/26
`[52] US. Cl. .................................... .. 385/146; 385/43;
`385/901; 385/129; 385/131
`[58] Field of Search ............... .. 385/43, 129, 130, 131,
`385/140, 146, 147, 901, 31; 359/599, 833, 834
`References Cited
`U'S_ PATENT DOCUMENTS
`2 347 665 5/1944 Ch _ t
`t 1
`2,712,593 7/1955 Merchant ............... ..
`3,617,109 l1/l97l Tlen ...... ..
`2:22:
`
`115 6115811 6 a . ............... ..
`
`362/31
`. 362/27
`385/43
`
`..
`
`. . . . .. 385/43
`,,,, ,_ 40/130
`. 353/122
`-
`“0/9615
`362/19
`_
`‘
`' ' " 350/9610
`____ ,_ 362/31
`. . . . .. 362/31
`---- -- 362/27
`
`1
`
`,
`
`ey et a .
`
`3,980,392 9/1976 Aunacher . . . . . . . . .
`4,059,916 11/1977 Tachihara c131,
`4,111,538 9/1978 Sheridon ........ ..
`gmsmnlu-
`4,176,908 12/1979 Wagner
`4212048 7/1980 Castleberry _
`4:240:692 12/1980 Winston . . . . . . .
`4,257,084 3/1981 Reynolds _
`4,277,817 7/1981 Hehr . . . . . . . .
`4,323,951 4/1982 Pasco
`an,“ '
`362/31
`4’453’2Oo 6/1984 T3;
`362/32
`4:528:617 7/1935 Blackingtm',
`.. 362/32
`4,547,043 10/1985 Penz ...................... ..
`350/345
`4,573,766 3/1986 Bournsy, Jr. et al. ..
`4,618,216 10/1986 Suzawa ....................... .. 359/49
`4,648,690 3/1987 Obe ................................... .. 350/321
`
`OTHER PUBLICATIONS
`“Flat Panel Backlight Re?ecting Device,” R. L. Gar
`win and R. T. Hodgson, IBM Technical Disclosure Bul
`mi", ‘'01- 3LN°~ 2,1111,- 19881181 1907191
`“Dielectric Totally Internally Re?ecting Concentra
`tors” Xisohui, Ming, Roland Winston and Joseph 0’
`Gallagher. Applied Optics, vol- 26, Jan- 15, 1987, pp
`300-305
`Primary Examiner-John D. Lee
`Assistant Examiner-Phan Thi Heartney
`Attorney, Agent, or Firm-Reinhart, Boerner, Van
`Deum’ N°ms 8‘ meselbach
`[57]
`ABSTRACT
`An optical device for collecting light and selectively
`
`‘
`
`‘
`
`-
`
`Outpumng 0r conccmratmg the llght- A Wedge layer
`has an optical index of refraction m, and top, bottom
`and side surfaces intersecting to de?ne an angle of incli
`nation d. A back surface spans the top, bottom and side
`surface. A ?rst layer 1s‘c0upled to the bottom surface of
`the layer and has an index of refraction n2. The ?rst
`layer index I12 causes light input through the back Sur
`:face of the layer to be preferentially output into the ?rst
`layer. A second layer is coupled to the bottom of the
`?rst layer and selectively causes output of light into
`ambient. Additional layers, such as an air gap, can be
`provided adjacent to the wedge shaped layer. The
`wedge shaped layer can also have a variable index of
`refraction 11 (1am)
`
`69 Claims, 23 Drawing Sheets
`
`VIZIO EX. 1018
`
`K.J. Pretech Ex. 1018
`
`Pretech_000742
`
`

`
`5,303,322
`Page 2
`
`US. PATENT DOCUMENTS
`
`4,838,661 6/1989 MCKCC 6161. .................... .. 350/345
`448424378 6/1939 Flack ?al- ----- --
`-- 350/345
`449071044 3/1990 S°h°11b°m °t 81-
`357/"
`449071132 3/1990 Parke‘ ------- --
`1362/32
`49144553 4/1990 Ham“ 6"
`362/321
`
`4,915,479 4/1990 Clarke .............. ..
`
`5,046,829 9/1991 Worp .................................. .. 359/49
`5,050,946 919
`.
`33
`5,051,551 561931
`‘ _
`' _ _ _ "2233441
`5,053,76510/1991 Sonehara 6161
`v340/61531
`5,083,120 1/1992 Nelson ................... .. 340/784
`5,101,325 3/1992 Davenport C13].
`362/31
`5,128,783 7/1992 Abilcah C131.
`359/49
`
`5,128,787 M992 Blonder _ _ ' i _ _
`
`_ _ _ _ _ . " 359/70
`
`5128846 7/1992 1611136161
`’
`’
`' """""""""""" "
`
`362/224
`
`OTHER PUBLICATIONS
`“Optics of Two-Stage Photovaltaic Concentrators
`with Die1ectric Second Stages”, Xisohul, Ning, Roland
`Winston and Joseph O’Gallagher, Applied Optics, v01.
`26, Apr. 1, 1987, pp. 1207-1212.
`“New Backlighting Technologies for LCDs”, Hatha
`way et a1., Society for Information Display Digest, v01. 22,
`May 1991, pp. 751-754. “Parts that Glow”, A. Bhurnen
`feld and S. Jones, Machine Design, Jul. 1985, pp. 1-11.
`“Directional Diffuser Lens Array for Backlit LCDs”,
`R. I. McCartney and D. Syroid, Japan Display, pp.
`259-262 (1992),
`
`358/345
`
`359/49
`362/32
`350/345
`362/247
`362/31
`. 40/4447
`.. 362/31
`350/96.10
`
`. . . .. 362/255
`
`362/147
`340/765
`359/49
`362/31
`
`. . . .. 350/345
`
`4,936,659 6/1990 Andcm" "*1
`4,950,059 8/1990 Roberts ........ ..
`4,958,915 9/1990 0116116 6131.
`4,965,876 10/1990 Foldi 61 81..
`4,974,122 11/1990 Shaw ..... ..
`4,974,353 12/1990
`Norfolk ..... ..
`4,985,809
`1/1991 Matsui et a1.
`4,989,933
`2/ 1991 Duguay ..... ..
`4,992,916
`4,998,188
`5,019,808
`5,039,207
`5,040,098
`5,040,878
`5,044,734
`5,046,805
`
`2/1991 Henkes . . . . . . . .
`
`3/ 1991 Degelmann .
`5/1991 Prince et al.
`8/1991 Green ............ ..
`8/1991 Tanaka et a1. ..
`
`8/1991 Eichenlaub . . . . .
`
`.. 359/49
`9/1991 Sperl et a1. ..
`9/1991 Simon ................................. .. 385/31
`
`Pretech_000743
`
`

`
`US. Patent
`
`Apr. 12, 1994
`
`Sheet 1 of 23
`
`5,303,322
`
`9' 7
`—:§;R ART---"\
`
`20
`
`e
`{)1
`
`‘f’
`
`Pretech_000744
`
`

`
`US. Patent
`
`Apr. 12, 1994
`
`Sheet 2 of 23
`
`5,303,322
`
`Pretech_000745
`
`

`
`US. Patent
`
`Apr. 12, 1994
`
`3 Sheet 3 of 23
`
`5,303,322
`
`/10
`
`gay. 25’
`
`38 42
`
`29
`
`.
`
`12
`
`10
`
`/
`
`Pretech_000746
`
`

`
`US. Patent
`
`_Apr.l2, 1994
`
`Sheet 4 of 23
`
`5,303,322
`
`Pretech_000747
`
`

`
`US. Patent
`
`Apr. 12, 1994
`
`Sheet 5 of 23
`
`5,303,322
`
`_
`
`/12
`
`/
`
`A
`
`—29
`
`.
`
`F
`
`49 ’
`
`29
`
`12
`1
`/
`
`/
`
`Pretech_000748
`
`

`
`US. Patent
`
`Apr. 12, 1994
`
`Sheet 6 of 23
`
`5,303,322
`
`94?. 404
`
`BRIGHTNESS
`8
`
`—90
`
`—60
`
`30
`0
`—30
`VIEWING ANGLE (DEGREES)
`
`60
`
`90
`
`Pretech_000749
`
`

`
`US. Patent
`
`Apr. 12,1994
`
`Sheet 7 of 23
`
`5,303,322
`
`BRIGHTNESS
`
`4%
`
`-18 T0 18
`
`--18 T0 30
`
`—90
`
`—60
`
`30
`0
`'
`-30
`VIEWING ANGLE (DEGREES)
`
`60
`
`90
`
`BRIGHTNESS
`81
`
`'
`6-
`
`_
`
`9' .42?
`I?
`
`0-? I"I I
`-90
`
`l
`
`I
`I
`l
`—60
`
`I
`
`I
`
`I
`
`I
`
`I
`
`I
`I
`I
`I III I
`I
`30
`0
`—30
`VIEWING ANGLE (DEGREES)
`
`I
`
`l
`
`I
`
`I
`
`I
`
`I
`
`l
`
`I
`
`l
`
`I
`I
`60
`
`I
`
`I
`
`I II
`90
`
`Pretech_000750
`
`

`
`US. Patent
`
`Apr. 12, 1994
`
`Sheet 8 of 23
`
`5,303,322
`
`BRIGHTNESS (fL.)
`
`5.4 -
`
`4 _
`
`3.5
`
`3__
`
`2.5
`
`2
`
`1.5 -
`
`.92? 42
`
`Pretech_000751
`
`

`
`US. Patent
`
`Apr. 12, 1994
`
`sheet 9 m3
`
`‘ 5,303,322
`
`3RIGHTNESS
`
`939.49
`
`BRIGHTNESS
`3201
`300
`280
`260
`240
`220
`200
`
`130 -
`
`I60 -
`
`140
`120 -
`
`10o -
`so
`so
`40
`20
`0
`
`IIIIII III III III III III Ill Ill II
`I
`I
`I
`I
`I
`I
`I
`—46 -38 -34 -30 —24 -18
`2
`10
`
`2I4
`
`4I2 ANGLE
`
`Pretech_000752
`
`

`
`US. Patent
`
`.Apr. 12, 1994
`
`Sheet 10 of 23
`
`5,303,322
`
`BRIGHTNESS
`500T
`45o
`
`‘°°'
`550-
`300
`
`250-
`
`200
`
`150 -
`
`100
`
`9 4%
`L?’
`
`50
`
`|
`
`l
`
`I
`
`|
`
`-24| - -s | o l a | 16
`-5e|-4al-4o|-
`-so ~52 - -3e -28 ~20 -12 -4 4 12
`ANGLE
`
`l
`
`l
`
`|
`
`l
`
`LUMINANCE (fL.)
`5003
`
`400-:
`
`zoo-I
`
`200-1
`
`100 -j
`
`VERTICAL ANGLE(DEGREES)
`
`Pretech_000753
`
`

`
`US. Patent
`
`Apr. 12, 1994
`
`Sheet 11 of 23
`
`5,303,322
`
`46
`\
`
`9
`
`r
`
`9a? 54
`
`52
`
`54(n2)
`
`66
`
`70
`
`68
`
`Pretech_000754
`
`

`
`U.S. Patent
`
`Apr. 12, 1994
`
`Sheet 12 of 23
`
`5,303,322
`
`-— PRIOR ART —
`
`979,. 7
`
`Pretech_000755
`
`

`
`US. Patent
`
`Apr. 12,1994
`
`Sheet 13 of 23
`
`5,303,322
`
`i H 2 O
`
`<
`
`TOP OF
`SCREEN CUTS OFF
`Y? \ \ _ PROGRESSIVELY
`
`\ \ \ \
`
`r———— 0=5o0 MM ~————-l \~
`
`Pretech_000756
`
`

`
`Pretech_000757
`
`

`
`U.S. Patent
`
`Apr. 12, 1994
`
`Sheet 15 of 23
`
`‘ 5,303,322
`
`Pretech_000758
`
`Pretech_000758
`
`

`
`US. Patent
`
`.Apr. 12, 1994
`
`Sheet 16 of 23
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`5,303,322
`
`Pretech_000759
`
`

`
`US. Patent
`
`Apr. 12,1994
`
`Sheet 17 of 23
`
`5,303,322
`
`Pretech_000760
`
`

`
`US. Patent
`
`' Apr. 12,1994
`
`Sheet 18 of 23
`
`5,303,322
`
`>90 9%,. 12%
`
`Pretech_000761
`
`

`
`U.S. Patent
`
`Apr. 12, 1994
`
`Sheet 19 of 23
`
`5,303,322
`
`w\
`
`.9599 72.9%
`
`12
`
`200
`
`202
`
`198
`
`Pretech_000762
`
`Pretech_000762
`
`

`
`U.S. Patent
`
`Apr. 12,1994
`
`Sheet 20 of 23
`
`5,303,322
`
`AREA
`
`
`
`Pretech_0007633
`
`Pretech_000763
`
`

`
`U.S. Patent
`
`Apr. 12, 1994
`
`Sheet 21 of 23
`
`5,303,322
`
`95?. 72.2
`
`10
`
`258
`
`256
`
`
`
`278
`
`276
`
`275
`
`Pretech_000764
`
`Pretech_000764
`
`

`
`U.S. Patent
`
`.Apr.12,1994
`
`Sheet 22 of 23
`
`5,303,322
`
`.9729. 761:4
`
`Pretech_000765
`
`Pretech_000765
`
`

`
`U.S. Patent
`
`Apr. 12, 1994
`
`Sheet 23 of 23
`
`5,303,322
`
`1//1: 35°-(0.133 DEG/MIN)-X
`«/12 = 35° +(o.133 DEG/MIN) -x
`
`,0,
`
`
`
`Pretech_000766
`
`Pretech_000766
`
`

`
`1
`
`5,303,322
`
`2
`
`TAPERED MULTILAYER LUMINAIRE DEVICES
`
`This is a continuation-in-part of copending applica-
`tion Ser. No. 07/855,838 filed on Mar. 23, 1992, U.S.
`Pat. No. 5,237,641.
`The present invention is concerned generally with a
`luminaire device for providing selected illumination.
`More particularly, the invention is concerned with ta-
`pered luminaires, such as a wedge or disc shape, for
`backlighting and control of angular range of illumina-
`tion and light concentration generally.
`A variety of applications exist for luminaire devices,
`such as, for liquid crystal displays. For flat panel liquid
`crystal displays, it is important to provide adequate
`backlighting while maintaining a compact
`lighting
`source. It is known to use wedge shaped optical devices
`for general illumination purposes. Light is input to such
`devices at the larger end; and light is then internally
`reflected off the wedge surfaces until the critical angle
`of the reflecting interface is reached, after which light is
`output from the wedge device. Such devices, however,
`have only been used to generally deliver an uncol-
`limated lighting output and often have undesirable spa-
`tial and angular output distributions. For example, some
`of these devices use white painted layers as diffuse re-
`flectors to generate uncollimated output light.
`It is therefore an object of the invention to provide an
`improved optical device and method of manufacture.
`It is another object of the invention to provide a
`novel three dimensional luminaire.
`It is a further object of the invention to provide an
`improved multilayer tapered luminaire for optical pur-
`poses, such as for controlled angular output backlight-
`mg.
`It is still another object of the invention to provide a
`novel tapered luminaire device for controlled transmis-
`sion or concentration of light.
`It is an additional object of the invention to provide a
`novel optical device for providing collimated illumina-
`tion from the device.
`_
`It is yet a further object of the invention to provide an
`improved tapered luminaire having an intervening air
`gap layer.
`It is still another object of the invention to provide a
`novel luminaire allowing controlled and focused output
`illumination, or controlled angular input for concentra-
`tion.
`It is yet a further object of the invention to provide an
`improved illumination system wherein a light source,
`such as a compound parabolic concentrator, a fluroes-
`cent tubular light source, or variable parametric func-
`tional source is coupled to a multilayer optical device
`for generating an output.
`It is still a further object of the invention to provide a
`novel luminaire optical device having a variable index
`of refraction over the spatial parameters of a luminaire.
`It is yet an additional object of the invention to pro-
`vide an improved luminaire wedge device having non-
`linear thickness variation and variable wedge angle 11>
`along selected spatial parameters enabling compensa-
`tion for light output irregularities.
`Other objects, features and advantages of the present
`invention will be readily apparent from the following
`description of the preferred embodiments thereof, taken
`in conjunction with the accompanying drawings de-
`scribed below.
`
`5
`
`10
`
`I5
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`55
`
`65
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 shows a prior art wedge shaped device;
`FIG. 2A illustrates a multilayer tapered luminaire
`device constructed in accordance with the invention;
`FIG. 2B is a magnified partial view of the junction of
`the wedge layer, the first layer and the second faceted
`layer; FIG. 2C is an exaggerated form of FIG. 2A
`showing a greatly enlarged second faceted layer; FIG.
`2D is a partial view of the junction of the three layers
`illustrating the geometry for brightness determinations;
`FIG. 2E is a multilayer wedge device with a light redi-
`recting,
`internally transmitting layer on the bottom;
`FIG. 2F shows a wedge device with a lower surface
`translucent layer; FIG. 2G shows a wedge layer with a
`lower surface refracting faceted layer; FIG. 2H shows a
`wedge layer with a lower surface refracting layer and
`curved facets thereon;
`FIG. 21 shows a wedge layer with a refracting layer
`of facets having variable facet angles; FIG. 23 shows a
`single refracting prism coupled to a wedge layer; FIG.
`2K shows a single refracting prism coupled to a wedge
`layer and with an integral lens; FIG. 2L shows a reflect-
`ing faceted layer coupled to a wedge device; FIG. 2M
`shows a reflecting faceted layer with curved facet an-
`gles and coupled to a wedge device; FIG. 2N shows a
`flat reflecting facet on a wedge layer and FIG. 20
`shows a curved reflecting facet on a wedge layer;
`FIG. 3 shows the angular output light due to the facet
`geometry.
`FIG. 3A illustrates a multilayer wedge device with
`curved facets on the ambient side of the second layer
`and FIG. 3B- shows a magnified partial view of the
`junction of the various layers of the device;
`FIG. 4A shows calculated brightness performance
`over angle for an asymmetric range of angles of illumi-
`nation; FIG. 4B shows calculated brightness distribu-
`tion performance over angle for a more symmetric
`angle range; FIG. 4C illustrates calculated brightness
`performance over angle for the symmetry of FIG. 4B
`and adding an external diffuser element; FIG. 4D illus-
`trates an output using flat reflecting facets, no parallel
`diffuser;
`full-width
`at
`half-maximum brightness
`(FWI-IM)= 7 degrees; FIG. 4E illustrates an example of
`nearly symmetrical output distribution; measured using
`flat facets with parallel lenticular diffuser; FWHM=34
`degrees; FIG. 4F illustrates an example of asymmetrical
`output distribution, measured using curved facets;
`FWHM=32 degrees; FIG. 4G illustrates an example
`asymmetrical output distribution, measured using
`curved facets; FWHM =26 degrees; FIG. 4H illustrates
`an example of a bimodal output distribution, measured
`using one faceted reflecting layer and one faceted re-
`fractive layer; and FIG. 41 illustrates an example of an
`output distribution with large “tails”, measured using a
`diffuse reflective bottom redirecting layer and a refrac-
`ting/intemally-reflecting top redirecting layer;
`FIG. 5A shows a top view of a disc shaped light
`guide and FIG. 5B illustrates a cross section taken along
`5B——5B in FIG. 5A;
`FIG. 6A shows a cross sectional view of a multilayer
`tapered luminaire device with an air gap layer included;
`FIG. 6B shows another tapered luminaire in cross sec-
`tion with a compound parabolic light source/concen-
`trator; FIG. 6C illustrates another tapered luminaire in
`cross section with a variable parametric profile light
`source and a lenticular diffuser; and FIG. 6D shows
`
`Pretech_000767
`
`Pretech_000767
`
`

`
`5,303,322
`
`4
`FIG. 17 shows a luminaire operative in ambient and
`active modes with a faceted redirecting layer and a
`lenticular diffuser; and
`FIGS. 18A & 18B illustrate a luminaire with an array
`of micro-prisms for a faceted surface disposed over a
`diffuse backlight.
`
`l0
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`55
`
`65
`
`DETAILED DESCRIPTION OF PREFERRED
`EMBODIMENTS
`
`A multilayer luminaire device constructed in accor-
`dance with one form of the invention is illustrated in
`FIG. 2 and indicated generally at 10. A prior art wedge
`11 is shown generally in FIG. 1. In this wedge 11 the
`light rays within the wedge 11 reflect from the surfaces
`until the angle of incidence is less than the critical angle
`(sin—ll/n) where n is the index of refraction of the
`wedge 11'. The light can exit equally from both top and
`bottom surfaces of the wedge 11, as well as exiting at
`grazing angles.
`The multilayer luminaire device 10 (hereinafter “de-
`vice 10”) shown in FIG. 2A includes a wedge layer 12
`which has a characteristic optical index of refraction of
`n1. The term “wedge layer” shall be used herein to
`include all geometries having converging top and bot-
`tom surfaces with wedge shaped cross sectional areas.
`The x, y and z axes are indicated within FIGS. 2A and
`2C with the “y” axis perpendicular to the paper. Typi-
`cal useful materials for the wedge layer 12 include al-
`most any transparent material, such as glass, polymethyl
`methacrylate, polystyrene, polycarbonate, polyvinyl
`chloride, methyl methacrylate/styrene
`copolymer
`(NAS) and sytrene/acrylonitrile. The wedge layer 12 in
`FIG. 2A further includes a top surface 14, a bottom
`surface 16, side surfaces 18, edge 26 and a back surface
`20 of thickness to spanning the top, bottom and side
`surfaces. A light source, such as a tubular fluorescent
`light 22, injects light 24 through the back surface 20 into
`the wedge layer 12. The light 24 is internally reflected
`from the various wedge layer surfaces and is directed
`along the wedge layer 12 toward the edge 26. Other
`possible light sources can be usedand will be described
`hereinafter. Generally, conventional light sources pro-
`vide substantially incoherent, uncollimated light; but
`coherent, collimated light can also be processed by the
`inventions herein.
`For the case where the surfaces 14 and 16 are flat, a
`single angle of inclination 4: for a linear wedge is de-
`fined by the top surface 14 and the bottom surface 16. In
`the case of nonlinear wedges, a continuum of angles :1)
`are definable; and the nonlinear wedge can be designed
`to provide the desired control of light output or concen-
`tration. Such a nonlinear wedge will be described in
`more detail later.
`In the embodiment of FIG. 2A a first layer 28 is
`coupled to the wedge layer 12 without any intervening
`air gap, and the first layer 28 has an optical index of
`refraction n2 and is optically coupled to the bottom
`surface 16. The first layer 28 can range in thickness
`from a few light wavelengths to much greater thick-
`nesses and accomplish the desired functionality. The
`resulting dielectric interface between the wedge layer
`12 and the first layer 28 has a higher critical angle than
`at the interface between the wedge layer 12 and ambi-
`ent. As will be apparent hereinafter, this feature can
`enable preferential angular output and collimation of
`the light 24 from the device 10.
`Coupled to the first layer 28 is a second layer 30 (best
`seen in FIG. 2B) having an optical index of refraction
`
`3
`another tapered luminaire in cross section with non-
`monotonic wedge layer thickness;
`FIG. 7 illustrates a reflective element disposed con-
`centrically about a light source;
`FIG. 8 illustrates a reflective element disposed about
`a light source with maximum displacement between the
`reflector center of curvature and the center of the light
`source;
`FIG. 9A illustrates use of a redirecting layer to pro-
`vide a substantially similar angular distribution emanat-
`ing from all portions of the device and FI_G. 9B illus-
`trates use of a redirecting layer to a vary angular distri-
`bution emanating from different portions of the device,
`and specifically to focus the various angular distribu-
`tions to enhance their overlap at a selected target dis-
`tance;
`FIG. 10 illustrates one form of pair of lenticular ar-
`rays of a luminaire; and
`FIG. 11 illustrates a lenticular diffuser array and
`curved facet layer of a luminaire;
`FIG. 12A illustrates a wedge shaped luminaire hav-
`ing a pair of diffraction gratings or hologram layers;
`FIG. 12B shows a wedge shaped luminaire with a pair
`of refracting facet layers and diffusers; FIG. 12C illus-
`trates a wedge shaped luminaire with a pair of faceted
`layers; FIG. 12D shows a wedge shaped luminaire with
`two refracting single facet layers; FIG. 12E illustrates a
`wedge shaped luminaire with a refracting single facet
`layer and a bottom surface redirecting layer; FIG. 12F
`shows a luminaire with a top surface redirecting layer
`of a refracting faceted layer and a bottom surface re-
`fracting and internally reflecting layer; FIG. 12G illus-
`trates a luminaire with a top surface refracting/inter-
`nally reflecting faceted layer and a bottom surface re-
`fracting/intemally reflecting faceted layer; FIG. 12H
`shows a luminaire with a top surface refracting faceted
`layer and a bottom surface refracting/intemally reflect-
`ing faceted layer; FIG. 121 illustrates a luminaire with a
`bottom surface specular reflector and a top layer trans-
`mission diffraction grating or transmission hologram;
`FIG. l2J shows a luminaire with a bottom surface spec-
`ular reflector and a top surface refracting faceted layer
`and diffuser; FIG. 12K illustrates a luminaire with a
`bottom layer specular reflector and a top layer refrac-
`ting/internally reflecting faceted layer; FIG. 12L shows
`a luminaire with a bottom specular reflector and a top
`layer
`refracting/intemally reflecting. faceted layer;
`FIG. 12M illustrates a luminaire with an initial reflector
`section including an integral lenticular diffuser; FIG.
`12N shows a luminaire with a roughened initial reflec-
`tor section of a layer; FIG. 120 illustrates a luminaire
`with an eccentric light coupler and converging to the
`wedge shaped section; FIG. l2P shows a luminaire with
`an eccentric light coupler and a diffuser and roughened
`or lenticular reflector; FIG. l2Q illustrates a luminaire
`with a bottom specular or diffusely reflecting layer and
`a top refracting layer and FIG. 12R shows a luminaire
`for generating a “bat wing" light output;
`FIG. 13 illustrates a combination of two wedge
`shaped sections formed integrally and using two light
`sources;
`FIG. 14 shows a tapered disk luminaire including a
`faceted redirecting layer;
`FIG. 15 illustrates a luminaire operating to provide a
`collimated light output distribution;
`FIG. 16A shows a prior art ambient mode LCD and
`FIG. 16B illustrates a prior art transflective LCD unit;
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`reflected back through the wedge layer 12. For exam-
`ple, in FIG. 2F the device 10 can include a translucent
`layer 37. In another form of this embodiment shown in
`FIG. 2G, a refracting layer 38 is shown. The refracting
`layer 38 can include flat facets 39 for providing a colli-
`mated output. Also shown in phantom in FIG. 2G is a
`transverse lenticular diffuser 83 which will be described
`in more detail hereinafter. The diffuser layer 83 can be
`used with any of the invention geometries, including
`above the wedge layer 12 as in FIG. 6A.
`In yet another example shown in FIG. 21-1, the re-
`fracting layer 38 can include curved facts 41 for provid-
`ing a smoothly broadened output over a desired angular
`distribution. In a further example shown in FIG. 21, the
`refracting layer 38 includes variable angle facets 42.
`These facets 42 have facet angles and/or curvature
`which are varied with position across the facet array to
`focus output light in a desired manner. Curved facets
`would enable producing a softly focused region within
`which the entire viewing screen appears to be illumi-
`nated. Examples of the application to compute screen
`illumination will be described hereinafter. In FIGS. 21
`and 2K are shown, respectively, a single refracting
`prism element 43 and the prism element 43 with an
`integral lens 44 to focus the output light. FIGS. 2L and
`M show the faceted surface 34 with the facets angularly
`disposed to control the output distribution of light. In
`FIGS. 2K and 2L the light is output to a focal point
`“F”, while in FIG. 2M the output is over an approxi-
`mate viewing range 45. FIGS. 2N and 20 illustrate flat
`reflecting facets 48 and curved reflecting facet 49 for
`providing a collimated light output or focused light
`output, respectively.
`As shown in FIGS. 2A and C the faceted surface 34
`optically reflects and redirects light 29 through the
`second layer 30, the first layer 28 and then through the
`wedge layer 12 into ambient. Only a fraction of each
`facet is illuminated, causing the output to appear alter-
`nately light and dark when viewed on a sufficiently
`small scale. Since this pattern is typically undesirable,
`for the preferred embodiment shown in FIG. 2B the
`period of spacing between each of the faceted surfaces
`34 is preferably large enough to avoid diffraction ef-
`fects, but small enough that the individual facets are not
`detected by the intended observing means. The spacing
`is also chosen to avoid forming Moiré interference pat-
`terns with any features of the device to be illuminated,
`such as a liquid crystal display or CCD (charge coupled
`device) arrays. Some irregularity in the spacing can
`rriitigate undesirable diffraction Moiré effects. For typi-
`cal backlighting displays, a spacing period of roughly
`0.001-0.003 inches can accomplish the desired purpose.
`The faceted surface 34 in FIGS. 2B and 2C, for exam-
`ple, can be generally prepared to control the angular
`range over which the redirected light 29 is output from
`the device 10. The minimum distribution of output
`angle in the layer 30 has a width which is approximately
`equal to:
`
`20
`
`25
`
`35
`
`45
`
`5,303,322
`
`5
`n3 which is greater than nz, and in some embodiments
`preferably greater than n1. This configuration then al-
`lows the light 24 to leave the first layer 28 and enter the
`second layer 30. In the embodiment of FIG. 2A there
`are substantially no intervening air gaps between the 5
`first layer 28 and the second layer 30. In the preferred
`form of the invention illustrated in FIG. 2A, n1 is about
`1.5, n2<l.5 and n3§n1. Most preferably, n1=l.5,
`n2<l.5 (such as about one) and n3§n1.
`In such a multilayer configuration for the device 10 10
`shown in FIG. 2, the wedge layer 12 causes the angle of
`incidence for each cyclic time of reflection from the top
`surface 14 to decrease by the angle of inclination 24>
`(relative to the normal to the plane of the bottom sur-
`face 16). When the angle of incidence with the bottom 15
`surface 16 is less than the critical angle characteristic of
`the interface between the wedge layer 12 and the first
`layer 28, the light 24 is coupled into the first layer 28.
`Therefore, the first layer 28 and the associated optical
`interface properties form an angular filter allowing the
`light 24 to pass when the condition is satisfied: 9<0¢.
`=sin-l (n2/n1). That is, the described critical angle is
`higher than for the interface between air and the wedge
`layer 12. Therefore, if the two critical angles differ by
`more than 6:12, nearly all of the light 24 will cross into
`the interface between the wedge layer 12 and the first
`layer 28 before it can exit the wedge layer 12 through
`the top surface 14. Consequently, if the two critical
`angles differ by less than :1), a substantial fraction, but
`less than half, of the light can exit the top surface 14. If 30
`the two angles differ by more than cl) and less than 64>,
`then substantially more than half but less than all the
`light will cross into the wedge layer 12 and the first
`layer 28 before it can exit the wedge layer 12 through
`the top surface 14. The device 10 can thus be con-
`structed such that the condition 9<0, is satisfied first
`for the bottom surface 16. The escaping light 24 (light
`which has entered the layer. 28) will then enter the
`second layer 30 as long as n3 > n2, for example. The light
`24 then becomes a collimated light 25 in the second
`layer 30 provided by virtue of the first layer 28 being
`coupled to the wedge layer 12 and having the proper
`relationship between the indices of refraction.
`In order to generate an output of the light 24 from the
`device 10, the second layer 30 includes means for scat-
`tering light, such as a paint layer 33 shown in FIG. 2B
`or a faceted surface 34 shown in both FIGS. 2B and 2C.
`The paint layer 33 can be used to preferentially project
`an image or other visual information. The paint layer 33
`can comprise, for example, a controllable distribution of 50
`particles having characteristic indices of refraction.
`By appropriate choice, light can also be redirected
`back through the wedge layer 12 and into ambient (see
`light 29 in FIGS. 2A and 2C) or output directly into
`ambient from the second layer 30 (see light 29’ in FIG. 55
`2F).
`In other forms of the invention a further plurality of
`layers with associated “n” values can exist. In one pre-
`ferred form of the invention the index of the lowest
`index layer can replace nz in equations for numerical
`aperture and output angle (to be provided hereinafter).
`Such further layers can, for example, by intervening
`between the wedge layer 12 and the first layer 28, inter-
`vening between the first layer 28 and the second layer
`30 or be overlayers of the wedge layer 12 or the second
`layer 30.
`In certain embodiments _the preferred geometries
`result in output of light into ambient without being
`
`Ao=2<i>i<m2—»-22)/<ns1—nz*)i4
`
`Thus, since 4) can be quite small, the device 10 can be
`quite an effective collimator. Therefore, for the linear
`faceted surface 34, the exiting redirected light 29 has a
`minimum angular width i air of approximately:
`
`A9811‘:Il3A9=2¢(Il]2-I122)/[I—(fl2/fl3)2]!-
`
`65
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`7
`As described hereinbefore, and as shown in FIGS. 2H,
`21, 2K, 2L, 2M, and FIG. 3 the facet geometry can be
`used to control angular output in excess of the minimum
`angle and also focus and control the direction of the
`output light.
`~
`Fresnel reflections from the various interfaces can
`also broaden the output angle beyond the values given
`above, but this effect can be reduced by applying an
`antireflection coating 31 on one or more of the internal
`interfaces, as shown in FIG. 2B.
`The brightness ratio (“BR”) for the illustrated em-
`bodiment can be determined by reference to FIG. 2D as
`well as by etendue match, and BR can be expressed as:
`
`B R _ output brightness
`‘
`' ' source brightness
`
`OI’,
`
`B.R.=illuminated area/total area
`
`ER. = [l — (nz/n3)2]9 =0.4—O.65 (for most transparent
`dielectric materials)
`
`the wedge layer 12 can be acrylic
`For example,
`(n1=1.49), the first layer 28 can be a fluoropolymer
`(n;:,= 1.28-1.43) or Sol-gel (n2= 1.05-1.35, fluoride salts
`(n2= 1.38-1.43) or silicone based polymer or adhesive
`(nz= 1.4-1.45); and the second layer 30 can be a faceted
`reflector such as polycarbonate (n3= 1.59), polystyrene
`(n3=l.59) epoxy (n3=1.5—l.55) or acrylic (n3=l.49)
`which have been metallized at the air interface.
`The flat, or linear, faceted surfaces 34 shown, for
`example, in FIGS. 2B and 2C can redirect the incident
`light 24 to control direction of light output and also
`substantially preserve the angular distribution of light
`A0 which is coupled into the second layer 30 by the
`angle-filtering effect (see, for example, FIG. 4D). For
`example, in one preferred embodiment shown in FIG.
`2L, the faceted surfaces 34 reflect light with the flat
`facet angles varied with position to focus the output
`light. In FIG. 2M the faceted surfaces 34 include curved
`facet angles which vary with position to produce a
`softly focused viewing zone 45 within which the entire
`screen appears to be illuminated (see also, for example
`FIGS. 4F and 4G). Also show in phantom in FIG. 2M
`is an exemplary liquid crystal display 47 usable in con-
`junction with the invention. As further shown in FIGS.
`3A and B, curved facets 36 also redirect the incident
`light 24, but the facet curvature increases the resulting
`range of angular output for the redirected light 29 (see
`for comparison for flat facets FIGS. 2D). For example,
`it is known that a concave trough can produce a real
`image, and that a convex trough can produce a virtual
`image (see, for example, FIG. 3B). In each case the
`image is equivalent to a line source emitting light uni-
`formly over the desired angular output range. Conse-
`quently, an array of such trough shaped facets 36 can
`redi