United States Patent [19J
`Ouderkirk et al.
`
`111111
`
`1111111111111111111111111111111111111111111111111111111111111
`US005828488A
`[11] Patent Number:
`[45] Date of Patent:
`
`5,828,488
`Oct. 27, 1998
`
`[54] REFLECTIVE POlARIZER DISPlAY
`
`FOREIGN PATENT DOCUMENTS
`
`[75]
`
`Inventors: Andrew J. Ouderkirk; Olester
`Benson, Jr., both of Woodbury;
`Sanford Cobb, Jr., St. Mary's Point,
`all of Minn.; James M. Jonza, Round
`Rock, Tex.; Michael F. Weber,
`Shoreview, Minn.; David L. Wortman;
`Carl A. Stover, both of St. Paul, Minn.
`
`[73] Assignee: Minnesota Mining and
`Manufacturing Co., St. Paul, Minn.
`
`[21] Appl. No.: 402,349
`
`[22] Filed:
`
`Mar. 10, 1995
`
`Related U.S. Application Data
`
`[63] Continuation-in-part of Ser. No. 171,239, Dec. 21, 1993,
`abandoned, Ser. No. 172,593, Dec. 21, 1993, abandoned,
`Ser. No. 359,436, Dec. 20, 1994, abandoned, and a continu(cid:173)
`ation-in-part of Ser. No. 360,204, Dec. 20, 1994, abandoned.
`Int. Cl.6
`.............................. G02B 5/30; G02B 27/28
`[51]
`[52] U.S. Cl. .......................... 359/487; 359/495; 359/497;
`359/498; 349/62; 349/96; 362/19
`[58] Field of Search ..................................... 359/485, 486,
`359/487, 488, 490, 491, 492, 493, 494,
`495, 496, 497, 498, 837; 362/19; 349/62,
`96
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
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`1,610,423
`2,492,809
`2,776,598
`2,887,566
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`3,480,502
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`3,528,723
`3,556,635
`
`5/1994 Schrenk et a!. ......................... 359!359
`12/1926 Cawley ..................................... 353/20
`12/1949 Marks ... ... ... ... .... ... ... ... ... ... .... ... ... 88/65
`1!1957 Dreyer ...................................... 88/105
`5/1959 Marks ...................................... 240/9.5
`10/1965 Rogers ........................................ 88/65
`1!1969 Lefevre . ... ... ... .... ... ... ... ... ... .... .. 264/171
`11/1969 Schrenk .................................. 156/271
`3/1970 Schrenk .................................. 161/109
`9/1970 Rogers .................................... 350/157
`1!1971 Schrenk et a!. ........................... 350/96
`
`1327286
`218041
`056843
`062751
`0 460 241 A1
`0 469 732 A3
`0 488 544 A1
`0 492 636 A1
`0 514 223
`0 552 725 A1
`0 573 905 A1
`0 597 261 A1
`0 606 939
`0 606 940
`41 21 861 A1
`181201
`
`3/1994
`12/1993
`8/1982
`10/1982
`12/1991
`2/1992
`6/1992
`7/1992
`11/1992
`7/1993
`12/1993
`5/1994
`7/1994
`7/1994
`1!1992
`7/1988
`
`Canada .... ... ... ... ... ... .... ... .. G02B 6/00
`China ........................... G02F 1!1335
`. ......... G02F 1/33
`European Pat. Off.
`European Pat. Off.
`. ......... G02B 1/08
`European Pat. Off ......... G02B 27/28
`. ......... G02B 1/04
`European Pat. Off.
`European Pat. Off ........... G02B 5!30
`European Pat. Off .......... H04N 9/31
`European Pat. Off ........... G02B 5!08
`European Pat. Off ......... G02B 27/28
`European Pat. Off ......... G02B 27/28
`. ..... G02F 1!1335
`European Pat. Off.
`European Pat. Off.
`. ..... G02F 1!1335
`European Pat. Off ........... G02B 5!30
`Germany ......................... G02B 5!30
`Japan ................................ F21V 5/02
`
`(List continued on next page.)
`
`OTHER PUBLICATIONS
`
`"Light Duffusing Film", Optical Systems, 3M 1993.
`Im et al, "Coextruded Microlayer Film and Sheet", Journal
`of Plastic Film and Sheeting, vol. 4, pp. 104-115 (Apr.,
`1988).
`MacLeod, H.A. Thin Film Optical Filters, Adam Hilger,
`London, 1969.
`Schrenk et al, "Coextruded Iridescent Film", TAPPI Paper
`Synthetics Conference, Atlanta, Georgia, pp. 141-145 (Sep.
`27-29, 1976).
`Schrenk et al, "Coextruded Multilayer Polymer Films and
`Sheet", Polymer Blends, vol. 2, 129, Ch. 15, pp. 129-165,
`Academic Press, Inc. (1978).
`Schrenk et al, "Interfacial Flow Instability in Multilayer
`Coextrusion", Polymer Engineering and Science, vol. 18(8):
`pp. 620--623 (Jun. 1978).
`
`(List continued on next page.)
`
`Primary Examiner---Ricky D. Shafer
`Attorney, Agent, or Firm-William D. Miller
`
`[57]
`
`ABSTRACT
`
`A brightness enhanced reflective polarizer includes a reflec(cid:173)
`tive polarizer and a structured surface material.
`
`(List continued on next page.)
`
`92 Claims, 32 Drawing Sheets
`
`~146
`/I\
`
`' - - - - - - - - - - - - - - - - ' 116
`
`149 }-"'
`
`110
`
`LG Display Ex. 1020
`
`LGD_001652
`
`

`

`5,828,488
`Page 2
`
`U.S. PATENT DOCUMENTS
`
`2/1971 Schrenk et a!. ... ... ... ... .... ... ... ... 264/171
`8/1971 Smith ...................................... 250/199
`10/1971 Rogers .................................... 350/157
`3/1972 Schrenk et a!. ......................... 161!165
`......................... 350/1
`1!1973 Alfrey, Jr. et a!.
`7/1973 Schrenk .................................. 425/131
`9/1973 Schrenk et a!. ......................... 425/131
`11/1973 Schrenk ... ... ... .... ... ... ... ... ... .... .. 264/171
`4/1974 Schrenk et a!. ......................... 161!181
`11/1974 Chisholm ................................ 65!99 A
`5/1977 Nagy et a!. ............................. 428/350
`6/1978 Alfrey, Jr. et a!.
`..................... 264/171
`2/1980 Mohler .................................... 340/705
`7/1980 Castleberry ............................... 362/19
`3/1981 Sperling et a!. .................... 260/23 ST
`5/1981 Oshima eta!. ......................... 350/337
`1!1982 Cooper et a!. .......................... 428/212
`2/1982 McKnight eta!. ..................... 340/784
`1!1984 Aizawa et a!. .......................... 428/332
`5/1984 Rogers et a!.
`.......................... 528/348
`5/1985 Rogers et a!.
`.......................... 528/331
`6/1985 Rogers et a!.
`.......................... 528/363
`6/1985 Rogers et a!.
`.......................... 428/212
`9/1985 Im et a!.
`................................. 428/220
`9/1985 Whitehead .............................. 362/330
`5/1986 Umeda et a!. .......................... 350/337
`5/1986 Kawakami et a!.
`.................... 428/216
`2/1987 Hosonuma et a!.
`.................... 350/337
`4/1987 Rogers et a!.
`........................... 264/1.3
`4/1987 Nosker ................................ 350/339 D
`7/1987 Ohta eta!. .............................. 350/345
`7/1988 Utsumi .................................... 428/220
`12/1988 Dreyer, Jr. et a!. ... ... ... .... ... ... .. 362/331
`1!1989 Tanaka et a!. . ... ... ... ... .... ... ... ... 350/337
`1!1989 van Raalte .............................. 350/345
`1!1989 Utsumi ................................ 350/339 R
`2/1989 Cobb, Jr ............................... 350/96.28
`4/1989 Nakamura et a!. ....................... 524/89
`6/1989 Clark et a!. .......................... 350!350 S
`11/1989 Whitehead .......................... 350/276 R
`1!1990 Onstott et a!. ....................... 350/96.33
`1!1990 Suznki et a!. .. ... ... ... ... .... ... ... ... 350/336
`3/1990 Olson et a!.
`........................... 350/96.3
`4/1990 Conner et a!. . ... ... ... ... .... ... ... ... 350/335
`6/1990 Schrenk et a!. ......................... 428/213
`8/1990 Bradshaw eta!. ...................... 350/102
`12/1990 Solomon ................................. 350/399
`1!1991 Owada et a!.
`............................ 358/61
`4/1991 Morimoto ................................ 350/6.5
`8/1991 Sato et a!. ................................. 359/40
`10/1991 Messerly et a!. ....................... 385/123
`10/1991 Cobb, Jr .................................. 359/831
`10/1991 Nakamura et a!. ..................... 252/585
`10/1991 Ogura ...................................... 359/490
`2/1992 Shetty et a!. ............................ 428/212
`3/1992 Aida et a!. ................................ 359/73
`3/1992 Schrenk et a!. ......................... 264/171
`3/1992 Schrenk et a!. ......................... 264/171
`...................... 250/339
`3/1992 Wheatley et a!.
`4/1992 Schrenk et a!. ......................... 359!359
`6/1992 Wheatley et a!.
`...................... 359/586
`6/1992 Wheatley ................................ 359/586
`6/1992 Oishi ....................................... 359/487
`6/1992 Wheatley et a!.
`...................... 359/587
`7/1992 Lehureau eta!. ....................... 350/301
`8/1992 Arakawa ................................... 350/73
`8/1992 Okumura .................................. 359/63
`9/1992 Wheatley et a!.
`...................... 428/213
`10/1992 Kondo eta!. ............................. 359/63
`10/1992 Akiyama eta!. ......................... 359/69
`
`3,565,985
`3,600,587
`3,610,729
`3,647,612
`3,711,176
`3,746,485
`3,759,647
`3,773,882
`3,801,429
`3,847,585
`4,025,688
`4,094,947
`4,190,832
`4,212,048
`4,254,002
`4,268,127
`4,310,584
`4,315,258
`4,427,741
`4,446,305
`4,520,189
`4,521,588
`4,525,413
`4,540,623
`4,542,449
`4,586,790
`4,590,119
`4,643,529
`4,659,523
`4,660,936
`4,678,285
`4,756,953
`4,791,540
`4,796,978
`4,798,448
`4,799,772
`4,805,984
`4,824,882
`4,840,463
`4,883,341
`4,896,942
`4,896,946
`4,906,068
`4,917,465
`4,937,134
`4,952,023
`4,974,946
`4,989,076
`5,009,472
`5,042,921
`5,056,888
`5,056,892
`5,059,356
`5,061,050
`5,089,318
`5,093,739
`5,094,788
`5,094,793
`5,095,210
`5,103,337
`5,122,905
`5,122,906
`5,124,841
`5,126,880
`5,134,516
`5,138,474
`5,139,340
`5,149,578
`5,157,526
`5,159,478
`
`5,166,817
`5,189,538
`5,194,975
`5,200,843
`5,202,074
`5,202,950
`5,217,794
`5,221,982
`5,233,465
`5,234,729
`5,237,446
`5,238,738
`5,245,456
`5,255,029
`5,262,894
`5,269,995
`5,278,680
`5,278,694
`5,286,418
`5,295,018
`5,303,083
`5,309,422
`5,316,703
`5,325,218
`5,333,072
`5,337,174
`5,339,179
`5,339,198
`5,345,146
`5,359,691
`5,360,659
`5,381,309
`5,389,324
`5,422,756
`5,448,404
`5,451,449
`5,486,949
`5,540,978
`5,552,927
`5,559,634
`5,568,316
`B1 4,660,936
`
`11/1992 Ota et a!. ... ... ... ... .... ... ... ... ... .... .. 359/73
`2/1993 Arakawa ................................... 359/73
`3/1993 Akatsnka eta!. ......................... 359/73
`4/1993 Karasawa et a!. ........................ 359/40
`4/1993 Schrenk et a!. .. ... .... ... ... ... ... .... 264/241
`4/1993 Arego eta!. ............................ 385/146
`6/1993 Schrenk .................................. 428/220
`6/1993 Faris .......................................... 359/93
`8/1993 Wheatley et a!.
`...................... 359!359
`8/1993 Wheatley et a!.
`........................ 428/30
`8/1993 Takahashi ............................... 350!359
`8/1993 Miller ...................................... 428/333
`9/1993 Yoshimi eta!. .......................... 359/73
`10/1993 Vogeley et a!. ......................... 353/122
`11/1993 Wheatley et a!.
`...................... 359/586
`12/1993 Ramanathan et a!. .................. 264/171
`1!1994 Karasawa et a!. ........................ 359/40
`1!1994 Wheatley et a!.
`...................... 359!359
`2/1994 Nakamura et a!. ..................... 252/585
`3/1994 Konuma et a!. ........................ 359/487
`4/1994 Blanchard et a!.
`..................... 359/495
`5/1994 Kuroki et a!.
`.......................... 369/110
`5/1994 Schrenk ................................... 264/1.3
`6/1994 Willett et a!. ............................. 359!53
`7/1994 Willett ....................................... 359/41
`8/1994 Wada eta!. ............................... 359/73
`8/1994 Rudisill et a!. ........................... 359/49
`8/1994 Wheatley et a!.
`...................... 359!359
`9/1994 Koenck et a!.
`...................... 315/169.3
`10/1994 Tai eta!. ................................. 385/146
`11/1994 Arends et a!.
`.......................... 428/216
`1!1995 Borchardt . ... ... ... ... ... .... ... ... ... ... .. 362/31
`2/1995 Lewis et a!. ............................ 264/171
`6/1995 Weber ..................................... 359/487
`9/1995 Schrenk et a!. ......................... 359/584
`9/1995 Shetty et a!. ............................ 428/195
`1!1996 Schrenk et a!. ......................... 359/498
`7/1996 Schrenk .................................. 428/212
`9/1996 Wheatley et a!.
`...................... 359!359
`9/1996 Weber ..................................... 359/638
`10/1996 Schrenk et a!. ......................... 359/584
`1!1990 Nosker ................................ 350/339 D
`
`FOREIGN PATENT DOCUMENTS
`
`4-141603
`4-184429
`5-288910
`6-11607
`6-222207
`2 052 779
`wo 91/09719
`wo 94/11776
`wo 94/29765
`wo 95/17303
`wo 95/17691
`wo 95/17692
`wo 95/17699
`
`5/1992
`7/1992
`11/1993
`1!1994
`8/1994
`1!1981
`7/1991
`5/1994
`12/1994
`6/1995
`6/1995
`6/1995
`6/1995
`
`Japan ............................... B02B 5!30
`Japan ............................. G03B 21!14
`Japan ............................... G02B 5/18
`Japan ............................... G02B 5/18
`Japan ............................... G02B 5!02
`United Kingdom ............ G02F 1/133
`WIPO ............................ B29C 43/20
`WIPO . ... .... ... ... ... ... .... ... G02F 1!1335
`WIPO . ... .... ... ... ... ... .... ... G02F 1!1335
`WIPO .............................. B32B 7/02
`WIPO .............................. G02B 5!30
`WIPO .............................. G02B 5!30
`WIPO . ... .... ... ... ... ... .... ... G02F 1!1335
`
`OTHER PUBLICATIONS
`
`Schrenk et al, "Coextruded Elastomeric Optical Interference
`Film", SPE Annual Technical Conference, Atlanta, Georgia,
`1703-7 (1988).
`Schenk et al, "Coextruder Infrared Reflecting Films", 7th
`Annual Meeting Polymer Processing Society Hamilton,
`Ontario, Canada (Apr. 1991).
`Schrenk, "New Developments in Coextrusion", Advances In
`Polymer Processing, New Orleans, Louisiana, (Apr., 1991).
`Wu et al, "High Transparent Sheet Polarizer Made with
`Birefringent Materials", Jpn. J. App. Phys., vol. 34, part 2,
`No. SA, pp. L997-999, Aug. 1995.
`
`LGD_001653
`
`

`

`5,828,488
`Page 3
`
`Derwent Abstract, JP 63017023.
`Abstract, Japan 62-295024, 1987.
`Abstract, Japan 63-168626, 1988.
`Abstract, Japan 4-356038, 1992.
`Alfrey, Jr. et al., "Physical Optics of Iridescent Multilayered
`Plastic Films", Polymer Engineering and Science, vol. 9,
`No. 6, Nov. 1969, pp. 400-404.
`Radford et al., "Reflectivity of Iridescent Coextruded Mul(cid:173)
`tilayered Plastic Films", presented at the American Chemi(cid:173)
`cal Society Symposium on Coextruded Plastic Films, Fibers,
`Composites, Apr. 9-14, 1972.
`3M
`IR-Compatible Safelight Kit,
`78-8063-2625-8, Jan. 1989, pp. 1-7.
`3M IR Safelight Brochure, 1991.
`Boese et al., "Chain Orientation and Anisotropies in Optical
`and Dielectric Properties in Thin Films of Stiff Polyimides",
`Journal of Polymer Science, Part B: Polymer Physics, vol.
`30, pp. 1321-1327 (1992).
`
`Instruction Sheet
`
`Baba et al., "Optical anisotropy of stretched gold island
`films: experimental results", Optics Letters, vol. 17, No. 8,
`Apr. 15, 1992.
`
`Weber, "Retrorefiecting Sheet Polarizer", SID conf. pro(cid:173)
`ceedings, Boston, MA, May 1992, SID 92 Digest, pp.
`427-429.
`
`Weber, "Retrorefiective Sheet Polarizer", SID conf. pro(cid:173)
`ceedings, Seattle, WA, May 1993, SID 93 Digest, pp.
`669-672.
`
`Hodgkinson et al., "Effective principal refractive indices and
`column angles for periodic stacks of thin birefringent films",
`Optical Society of Ameria, vol. 10, No. 9, pp. 2065-2071,
`Sep. 1993.
`
`Zang et al., "GiantAnistropies in the Dielectric Properties of
`Quasi-Epitaxial Crystalline Organic Semiconductor Thin
`Films".
`
`LGD_001654
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 1 of 32
`
`5,828,488
`
`A
`II\
`
`60
`
`' ' ' '
`
`' ' ' '
`
`10
`
`12
`
`24
`
`Fig. 1
`
`15
`
`36
`Fig.2
`
`39
`
`11
`
`LGD_001655
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 2 of 32
`
`5,828,488
`
`/17
`18
`¥
`~---------------·----~~20
`
`14
`
`~12
`~I
`
`19
`
`21
`
`~'~) ----------~~
`
`24
`
`Fig.3
`
`Y'12
`
`Fig.4
`
`LGD_001656
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 3 of 32
`
`5,828,488
`
`31
`
`100
`
`80
`
`60
`
`o/oT
`
`500
`
`600
`A(nm)
`Fig.5
`
`700
`
`LGD_001657
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 4 of 32
`
`5,828,488
`
`\
`
`' '
`
`' '
`
`164
`
`K146
`
`/I\
`~133
`
`}42
`
`}110
`
`140
`./
`
`113
`
`116
`
`163
`
`Fig.6
`
`238
`
`240
`
`242
`Fig.7
`
`LGD_001658
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 5 of 32
`
`5,828,488
`
`Fig.8
`
`K""146
`II\
`
`152 (a,c)
`
`148
`(a,b,c,d)
`
`154 (a,b,c,d)
`
`140
`157 (a,b,c,d) Fig. 9
`
`156 (b,c,d)
`
`LGD_001659
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 6 of 32
`
`5,828,488
`
`170
`
`17(_(
`
`1
`
`173
`
`Fig. 10
`
`~146
`/I\
`
`147
`
`(
`
`I
`
`- t-
`- r-
`
`113
`
`~116 110
`
`140
`
`143
`
`139 Fig. 11
`
`LGD_001660
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 7 of 32
`
`5,828,488
`
`160
`
`140
`
`40
`
`20
`
`a~-r~--+--r~--+--r-+--r-~-r~--+-~
`5 1 0 15 20 25 30 35 40 45 50 55 60 65 70
`0
`Degrees off normal
`Fig. 12
`
`~146
`I 1\
`
`149
`
`110
`
`-----------------------,
`--------------------------- _j 137
`
`Fig. 13
`
`l:c:
`
`139
`
`140
`
`LGD_001661
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 8 of 32
`
`5,828,488
`
`114
`
`A
`
`A
`
`A
`
`123
`
`122
`
`A
`118
`y
`Fig. 14
`
`B
`
`B
`
`B
`
`116
`
`141{
`
`138{
`
`124
`
`LGD_001662
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 9 of 32
`
`5,828,488
`
`y100
`
`102
`
`104
`
`n1y ..
`
`n2y,..
`
`no
`
`n1zt
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`Fig. 15
`
`-v
`
`LGD_001663
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 10 of 32
`
`5,828,488
`
`a
`
`d
`
`0.05
`
`0.04
`
`~ 0.03
`>
`I-
`() w
`...J 0.02
`u. w
`a:
`
`0.01
`
`0+-~--~~~~~~--~~~
`10 20 30 40 50 60 70 80 90
`0
`ANGLE OF INCIDENCE IN 1.60 MEDIUM
`Fig.16
`
`0.05
`
`0.04
`
`~ 0.03
`>
`i=
`() w
`...J 0.02
`u. w
`a:
`
`0.01
`
`0+-~--~~~--~~~--~~
`1 0 20 30 40 50 60 70 80 90
`0
`ANGLE OF INCIDENCE IN 1.60 MEDIUM
`Fig.17
`
`LGD_001664
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 11 of 32
`
`5,828,488
`
`0.012
`
`0.01
`
`~ 0.008
`>
`G w
`lL w
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`g
`h
`
`0+---~~~--~~--~~~--~
`0
`1 0 20 30 40 50 60 70 80 90
`ANGLE OF INCIDENCE IN 1.00 MEDIUM
`Fig.l8
`
`INDEX
`
`IN-PLANE
`INDEX 1
`n1z
`
`n2z
`
`IN-PLANE
`INDEX 2
`ISOTROPIC
`CASE
`
`I INCREASING
`I BREWSTER
`ANGLE
`
`Fig. 19
`
`NO BREWSTER ANGLE,
`R CONSTANT
`
`NO BREWSTER ANGLE,
`R INCREASES WITH ANGLE
`
`t
`
`LGD_001665
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 12 of 32
`
`5,828,488
`
`INDEX
`
`n1z
`
`IN-PLANE
`INDEX 1
`
`ISOTROPIC
`CASE
`
`INDEX
`
`IN-PLANE
`INDEX 1
`n1z
`
`IN-PLANE
`INDEX 2
`n2z
`ISOTROPIC
`CASE
`
`DECREASING
`BREWSTER
`ANGLE
`
`Fig.20
`
`I NO BREWSTER
`ANGLE,
`RINCREASES
`WITH ANGLE
`
`INCREASING
`BREWSTER
`ANGLE
`Fig.21
`
`LGD_001666
`
`

`

`U.S. Patent
`1.0
`
`Oct. 27, 1998
`
`Sheet 13 of 32
`
`5,828,488
`
`0.8
`
`~ 0.6
`
`I
`
`(!J
`
`0 -t 0.4
`
`0.2
`
`400
`
`450
`
`600
`550
`500
`WAVELENGTH (nm)
`Fig.22
`
`650
`
`700
`
`0.0001
`
`0.00008
`
`~
`> 0.00006
`1-
`() w
`lL w 0.00004
`a:
`
`_J
`
`0.00002
`
`0
`
`1 0 20 30 40 50 60 70 80 90
`ANGLE OF INCIDENCE IN 1.00 MEDIUM
`Fig.23
`
`LGD_001667
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 14 of 32
`
`5,828,488
`
`0.0001
`
`0.00008
`
`~
`> 0.00006
`.__
`()
`w
`.....J u. 0.00004
`w
`a:
`
`0.00002
`
`Q+---~~~~~~~~~~~-.
`1 0 20 30 40 50 60 70 80 90
`0
`
`ANGLE OF INCIDENCE IN 1.00 MEDIUM
`Fig.24
`
`LGD_001668
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 15 of 32
`
`5,828,488
`
`0.02
`
`0.01
`
`>. c
`<l
`
`0
`
`-0.01
`
`-0.02 ..___._ __ _.__ _
`-0.075
`-0.05
`
`____._ __ ......._ _ __._ __ ......._ _ __.__
`-0.025
`0
`0.025
`0.05 0.075
`6nz
`Fig.25
`
`LGD_001669
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 16 of 32
`
`5,828,488
`
`100
`
`80
`
`c:
`0
`"(i) 60
`.!a
`E
`en
`c: ro
`t= 40
`?fl.
`
`20
`
`o+-----+-----4-----4-----~-----r----~
`650
`600
`550
`700
`500
`450
`400
`Wave Length (nm)
`Fig.26
`
`LGD_001670
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 17 of 32
`
`5,828,488
`
`100
`
`80
`
`c
`0 60
`·u;
`-~
`E
`(/) c
`~ 40
`1-
`~ 0
`
`20
`
`0+-----4-----,_-----r----~-----+-----4
`700
`650
`600
`550
`500
`450
`400
`Wave Length (nm)
`Fig.27
`
`LGD_001671
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 18 of 32
`
`5,828,488
`
`100
`
`80
`
`(/)
`
`c
`0
`"(j) 60
`.E
`(/) c
`~ .__ 40
`#-
`
`20
`
`0+-----~-----+----~r-----+-----~-----1
`650
`600
`550
`400
`500
`700
`450
`Wave Length (nm)
`Fig.28
`
`LGD_001672
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 19 of 32
`
`5,828,488
`
`100
`
`80
`
`(fJ
`
`c:
`0
`"(j) 60
`E
`(fJ c:
`~
`I- 40
`?ft.
`
`20
`
`0+---~-----r----~--~r----T----~--~
`400
`11 00
`1 000
`900
`800
`700
`500
`600
`Wave Length (nm)
`Fig.29
`
`LGD_001673
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 20 of 32
`
`5,828,488
`
`100
`
`80
`
`c::
`0
`·u; 60
`-~
`E
`V) c:
`~
`r 40
`~ 0
`
`20
`
`o+-----4-----~-----+----~------~----;
`650
`600
`700
`550
`500
`450
`400
`Wave Length (nm)
`Fig.30
`
`LGD_001674
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 21 of 32
`
`5,828,488
`
`r::::
`0
`"(j)
`(/)
`
`E
`(/)
`r::::
`~
`1-
`cf-
`
`400
`
`500
`
`700
`600
`Wave Length (nm)
`Fig.31
`
`800
`
`LGD_001675
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 22 of 32
`
`5,828,488
`
`100
`
`80
`
`c: 60
`0
`·c;;
`-~
`E
`en
`c:
`~
`I- 40
`~ 0
`
`20
`
`0+-------;--------r-------+------~----
`400
`600
`800
`500
`700
`Wave Length (nm)
`Fig.32
`
`LGD_001676
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 23 of 32
`
`5,828,488
`
`100
`
`c
`0 ·u;
`.~
`E
`en c
`~
`I- 40
`'if-
`
`20
`
`OL--------L--------L-------~--------~
`800
`700
`600
`500
`400
`Wave Length (nm)
`Fig.33
`
`LGD_001677
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 24 of 32
`
`5,828,488
`
`100
`
`80
`
`c:
`0 ·u; 60
`.~
`E
`(/)
`c:
`.._
`ctS
`.... 40
`"#-
`
`20
`
`0+--------r--------r-------4--------;----
`700
`600
`800
`500
`400
`Wave Length (nm)
`Fig.34
`
`LGD_001678
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 25 of 32
`
`5,828,488
`
`c:
`0 ·u; 60
`.~
`E
`en
`c:
`~
`t- 40
`~
`
`20
`
`OL-------~~--~~--~---L------~---
`400
`500
`600
`700
`800
`Wave Length (nm)
`Fig.35
`
`LGD_001679
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 26 of 32
`
`5,828,488
`
`100
`
`80
`
`z
`0 60
`CJ)
`CJ)
`~
`CJ) z
`~ 40
`t-
`
`20
`
`0~~==~~----~~~-----4------~
`700
`600
`400
`500
`800
`WAVE LENGTH (nm)
`Fig.36
`
`LGD_001680
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 27 of 32
`
`5,828,488
`
`0
`0 co
`
`0
`0
`f'..
`
`0
`0
`<0
`
`0
`0
`LO
`
`~
`
`-E
`c -J:
`(!} z w
`...J
`w
`~
`~
`
`~
`~
`• biJ
`.....
`~
`
`0
`~~~~~--~--+0
`o"'d'"
`o
`o
`o
`o
`o
`co
`<0
`"'d'"
`0
`C\1
`
`o/o TRANSMISSION
`
`LGD_001681
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 28 of 32
`
`5,828,488
`
`100
`
`90
`
`80
`z 70
`0
`(/)
`(J) 60
`:::?!
`(J) z 50
`~ ..... 40
`'#
`30
`
`20
`
`10
`
`0
`400
`
`600
`500
`WAVE LENGTH (nm)
`Fig.38
`
`700
`
`800
`
`LGD_001682
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 29 of 32
`
`5,828,488
`
`100
`
`80
`
`z
`0
`en 60
`en
`~ en z
`< g: 40
`
`;::g
`0
`
`20
`
`0+--------+--------r-------~------~
`700
`600
`500
`800
`400
`WAVE LENGTH (nm}
`Fig.39
`
`LGD_001683
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 30 of 32
`
`5,828,488
`
`100
`
`80
`
`c:
`0
`·c;; 60
`.!:a
`
`E en c: e
`
`1-
`~40
`
`20
`
`500
`
`600
`Wave Length (nm)
`Fig. 40A
`
`700
`
`800
`
`LGD_001684
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 31 of 32
`
`5,828,488
`
`b
`
`100
`
`80
`
`c:
`0
`.(/) 60
`.~
`E
`(/) c:
`~ .._
`~40
`
`20
`
`500
`
`600
`Wave Length (nm)
`Fig. 40B
`
`700
`
`800
`
`LGD_001685
`
`

`

`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 32 of 32
`
`5,828,488
`
`b
`
`a
`
`100
`
`80
`
`c
`0
`·u.; 60
`en
`.E
`en c
`~
`1-
`~40
`
`20
`
`500
`
`600
`Wave Length (nm)
`Fig. 40C
`
`700
`
`800
`
`LGD_001686
`
`

`

`1
`REFLECTIVE POLARIZER DISPLAY
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS
`
`This is a continuation in part of U.S. patent application
`Ser. Nos. 08/171,239 and 08/172,593, which were filed Dec.
`21, 1993, now abandoned and is a continuation in part of
`U.S. patent application Ser. Nos. 08/359,436 and 08/360,
`204, which were filed Dec. 20, 1994, now abandoned all of
`which are incorporated herein by reference.
`
`TECHNICAL FIELD
`
`The invention is an improved optical display.
`
`BACKGROUND
`
`Optical displays are widely used for lap-top computers,
`hand-held calculators, digital watches and the like. The
`familiar liquid crystal (LC) display is a common example of
`such an optical display. The conventional LC display locates 20
`a liquid crystal and an electrode matrix between a pair of
`absorptive polarizers. In the LC display, portions of the
`liquid crystal have their optical state altered by the applica(cid:173)
`tion of an electric field. This process generates the contrast
`necessary to display "pixels" of information in polarized
`light.
`For this reason the traditional LC display includes a front
`polarizer and a rear polarizer. Typically, these polarizers use
`dichroic dyes which absorb light of one polarization orien(cid:173)
`tation more strongly than the orthogonal polarization orien(cid:173)
`tation. In general, the transmission axis of the front polarizer
`is "crossed" with the transmission axis of the rear polarizer.
`The crossing angle can vary from zero degrees to ninety
`degrees. The liquid crystal, the front polarizer and rear
`polarizer together make up an LCD assembly.
`LC displays can be classified based upon the source of
`illumination. "Reflective" displays are illuminated by ambi(cid:173)
`ent light that enters the display from the "front." Typically
`a brushed aluminum reflector is placed "behind" the LCD
`assembly. This reflective surface returns light to the LCD
`assembly while preserving the polarization orientation of the
`light incident on the reflective surface.
`It is common to substitute a "backlight" assembly for the
`reflective brushed aluminum surface in applications where
`the intensity of the ambient light is insufficient for viewing.
`The typical backlight assembly includes an optical cavity
`and a lamp or other structure that generates light. Displays
`intended to be viewed under both ambient light and backlit
`conditions are called "transflective." One problem with 50
`transflective displays is that the typical backlight is not as
`efficient a reflector as the traditional brushed aluminum
`surface. Also the backlight randomizes the polarization of
`the light and further reduces the amount of light available to
`illuminate the LC display. Consequently, the addition of the 55
`backlight to the LC display makes the display less bright
`when viewed under ambient light.
`Therefore, there is a need for a display which can develop
`adequate brightness and contrast under both ambient and
`backlight illumination.
`
`SUMMARY
`The optical display of the present invention comprises
`three basic elements. The first element is a reflective polar(cid:173)
`izer. This reflective polarizer is located between a liquid
`crystal display (LCD) assembly and an optical cavity, which
`comprise the second and third elements respectively.
`
`5,828,488
`
`2
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`5
`
`15
`
`The drawings depict representative and illustrative imple(cid:173)
`mentations of the invention. Identical reference numerals
`refer to identical structure throughout the several figures,
`wherein:
`FIG. 1 is a schematic cross section of an optical display
`according to the invention;
`FIG. 2 is a schematic cross section of an illustrative
`10 optical display according to the invention;
`FIG. 3 is a schematic cross section of an illustrative
`optical display according to the invention;
`FIG. 4 is an exaggerated cross sectional view of the
`reflective polarizer of the invention;
`FIG. 5 shows the optical performance of the multilayer
`reflective polarizer of Example 2;
`FIG. 6 is a schematic diagram of an optical display
`according to the invention with brightness enhancement;
`FIG. 7 is a diagram illustrating the operation of a bright(cid:173)
`ness enhancer;
`FIG. 8 is a graph illustrating the operation of a brightness
`enhancer;
`FIG. 9 is a schematic cross section of an illustrative
`25 optical display;
`FIG. 10 is a schematic cross section of an illustrative
`optical display;
`FIG. 11 is a schematic cross section of an illustrative
`30 optical display;
`FIG. 12 is a graph of test results;
`FIG. 13 is a schematic cross section of an illustrative
`optical display;
`FIG. 14 is a schematic cross section of a brightness
`35 enhanced reflective polarizer;
`FIG. 15 shows a two layer stack of films forming a single
`interface.
`FIGS. 16 and 17 show reflectivity versus angle curves for
`40 a uniaxial birefringent system in a medium of index 1.60.
`FIG. 18 shows reflectivity versus angle curves for a
`uniaxial birefringent system in a medium of index 1.0.
`FIGS. 19, 20 and 21 show various relationships between
`in-plane indices and z-index for a uniaxial birefringent
`45 system.
`FIG. 22 shows off axis reflectivity versus wavelength for
`two different biaxial birefringent systems.
`FIG. 23 shows the effect of introducing a y-index differ(cid:173)
`ence in a biaxial birefringent film with a large z-index
`difference.
`FIG. 24 shows the effect of introducing a y-index differ(cid:173)
`ence in a biaxial birefringent film with a small z-index
`difference.
`FIG. 25 shows a contour plot summarizing the informa(cid:173)
`tion from FIGS. 18 and 19;
`FIGS. 26-31 show optical performance of multilayer
`mirrors given in Examples 3-6;
`FIGS. 32-36 show optical performance of multilayer
`60 polarizers given in Examples 7-11;
`FIG. 37 shows optical performance of the multilayer
`mirror given in Example 12;
`FIG. 38 shows optical performance of the AR coated
`65 polarizer given in Example 13;
`FIG. 39 shows optical performance of the polarizer given
`in Example 14; and
`
`LGD_001687
`
`

`

`5,828,488
`
`3
`FIGS. 40A-40C show optical performance of multilayer
`polarizers given in Example 15.
`
`DETAILED DESCRIPTION
`
`FIG. 1 is a schematic diagram of an illustrative optical
`display 10 that includes three principle components. These
`include the polarizing display module shown as LCD assem(cid:173)
`bly 16, a reflective polarizer 12, and an optical cavity 24.
`The LCD assembly 16 shown in this figure is illuminated
`by polarized light provided by the reflective polarizer 12 and 10
`the optical cavity 24.
`Ambient light incident on the display 10, depicted by ray
`60 traverses the LCD module 16, the reflective polarizer 12
`and strikes the diffuse reflective surface 37 of the optical
`cavity 24. Ray 62 depicts this light as it is reflected by the
`diffusely reflective surface 37 toward the reflective polarizer
`12.
`Light originating from within the optical cavity 24 is
`depicted by ray 64. This light is also directed toward the
`reflective polarizer 12 and passes through the diffusely
`reflective surface 37. Both ray 62 and ray 64 have light
`exhibiting both polarization states ( a,b ).
`FIG. 2 shows a schematic optical display 11 illustrated
`with a three layer LCD assembly 15 that includes a front
`polarizer 18, a liquid crystal 20 and a rear polarizer 23. In
`this embodiment the optical cavity 24 is an edge lit backlight
`which includes a lamp 30 in a reflective lamp housing 32.
`Light from the lamp 30 is coupled to the light guide 34
`where it propagates until it encounters a diffuse reflective
`structure such as spot 36. This discontinuous array of spots
`is arranged to extract lamp light and direct it toward the LCD
`module 15. Ambient light entering the optical cavity 24 may
`strike a spot or it may escape from the light guide through
`the interstitial areas between spots. The diffusely reflective 35
`layer 39 is positioned below the light guide 34 to intercept
`and reflect such rays. In general, all the rays that emerge
`from the optical cavity 24 are illustrated by ray bundle 38.
`This ray bundle is incident on the reflective polarizer 12
`which transmits light having a first polarization orientation 40
`referred to as "(a)" and effectively reflects light having the
`orthogonal polarization orientation (b). Consequently, a cer(cid:173)
`tain amount of light, depicted by ray bundle 42, will be
`transmitted by the reflective polarizer 12 while a substantial
`amount of the remaining light will be reflected as indicated 45
`by ray bundle 40. The preferred reflective polarizer material
`is highly efficient and the total losses due to absorption
`within the reflective polarizer 12 are very low (on the order
`of 1 percent). This lost light is depicted by ray bundle 44.
`The light having polarization state (b) reflected by the 50
`reflective polarizer 12 reenters the optical cavity 24 where it
`strikes the diffusely reflective structures such as spot 36 or
`the diffusely reflective layer 39. The diffusely reflective
`surfaces serve to randomize the polarization state of the light
`reflected by the optical cavity 24. This recirculation and 55
`randomization process is depicted as path 48. The optical
`cavity 24 is not a perfect reflector and the light losses in the
`cavity due to scattering and absorption are depicted by ray
`bundle 46. These losses are also low (on the order of 20
`percent). The multiple recirculations effected by the combi- 60
`nation of the optical cavity 24 and the reflective polarizer 12
`form an efficient mechanism for converting light from state
`(b) to state (a) for ultimate transmission to the viewer.
`The effectiveness of this process relies on the low absorp(cid:173)
`tion exhibited by the reflective polarizer disclosed herein 65
`and the high reflectivity and randomizing properties exhib(cid:173)
`ited by many diffusely reflective surfaces. In FIG. 2 both the
`
`15
`
`4
`discontinuous layer depicted by spot 36 and the diffusely
`reflective continuous layer 39 may be form