Ulllted States Patent [19]
`Ouderkirk et al.
`
`US005828488A
`[11] Patent Number:
`[45] Date of Patent:
`
`5,828,488
`Oct. 27, 1998
`
`[54] REFLECTIVE POLARIZER DISPLAY
`
`FOREIGN PATENT DOCUMENTS
`
`.
`
`-
`
`.
`
`(lifi?rggvkoggiief
`[75] Inventors‘ ‘12225;?
`,
`"
`,y’
`’
`sanfordcobbr Jr» St- Mary S P°1nt>
`all of Mlm; Jfimes M- J°I1Za> Round
`Rock, Tex; Mlchael F- Weber,
`ShorevieW, Minn.; David L. Wortman;
`Carl A. Stover, both of St, Paul, Minn,
`
`Assigneez Minnesota Mining and
`Manufacturing Co” St Paul, Minn
`
`[21] APPI- NO-I 402,349
`.
`_
`[22] Flled"
`
`Mar‘ 10’ 1995
`
`1327286 3/1994 Canada .......................... .. G02B 6/00
`
`218041 12/1993 China ...................... .. G02F 1/1335
`056843 8/1982 European Pat. Off. ........ .. G02F 1/33
`062751 10/1982 European Pat. on.
`G02B 1/08
`0 460 241 A1 12/1991 European Pat. on.
`GOZB 27/28
`0 469 732 A3 2/1992 European Pat. on.
`G02B 1/04
`O 488 544 A1 6/1992 European Pat. Off.
`GOZB 5/30
`0 492 636 A1 7/1992 European Pat. Off ....... .. H04N 9/31
`0 514 223 11/1992 European Pat. Off. ........ .. G02B 5/08
`725 A1 7/1993 European Pat.
`...... .. G02B 27/28
`0
`0 573 905 A1 12/1993 European Pat. on. ...... .. GOZB 27/28
`0 597 261 A1 5/1994 European Pat. Off. .... .. G02F 1/1335
`0 606 939
`7/1994 European Pat. Off. .... .. G02F 1/1335
`0 606 940 7/1994 European Pat. on. ........ .. G02B 5/30
`41 21 861 A1 1/1992 Germany ............. ..
`G02B 5/30
`181201
`7/1988 Japan .............................. .. F21V 5/02
`
`Related US. Application Data
`
`(List continued on next page.)
`
`[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-
`ation-in-part of Ser. No. 360,204, Dec. 20, 1994, abandoned.
`Int. Cl? ............................ .. G02B 5/30; G02B 27/28
`
`[51]
`
`OTHER PUBLICATIONS
`“ .
`.
`.
`,,
`.
`Llght Duffusmg Fllm >_Opnca1 SY§temS> 3M 1993'
`1m 61 211, “COfJXmldfJd Mlcrolayer FllIIl and Sheet”, Journal
`ilgslgasnc F‘lm and Sheetmg’ V01‘ 4’ pp‘ 104415 (AW
`
`[52] US. Cl. ........................ .. 359/487; 359/495; 359/497;
`
`MaCLeOd, IiA~ Thin Film Optical Filters, Adam Huger,
`
`[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
`5/1994 Schrenk et al.
`
`Re. 34,605
`
`.. 359/359
`
`schrenk et a1, “Coextrnded Iridescent Film”, TAPPI Paper
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`27_29, 1976)'
`Schrenk et al, “Coextruded Multilayer Polymer Films and
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`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).
`
`1,610,423 12/1926 CaWley . . . . . . . . .
`
`. . . . .. 353/20
`
`2,492,809 12/1949 Marks
`88/65
`2,776,598
`1/1957 Dreyer ..
`.. 88/105
`2,887,566
`5/1959 Marks .................................... .. 240/95
`3,213,753 10/1965 Rogers ...................................... .. 88/65
`3,423,498
`1/1969 Lefevre
`264/171
`3,480,502 11/1969 Schrenk
`156/271
`g/
`lsfhrenk
`/
`/
`Ogers """"""""""""""""""" "
`1/1971 Schrenk et al. ......................... .. 350/96
`
`’
`’
`3,556,635
`
`_
`
`_
`
`(L1St Contlnued 0n neXt Page)
`.
`.
`.
`_
`P ’ lmary Examme’ _R_1Cky D; shafer
`Attorney) Agent) 0’ Flrm_W1111am D- M111“
`
`ABSTRACT
`[57]
`Abrightness enhanced re?ective polariZer includes a re?ec
`tive polariZer and a structured surface material.
`
`(List continued on next page.)
`
`92 Claims, 32 Drawing Sheets
`
`146
`AK
`
`149
`i
`
`/4—147
`
`I
`
`116
`‘V
`
`/\/\/{9\/\/\/\/><113
`116a/’L"—»—"_—"—'"—"—l
`
`192 —-———-—--——--—-——--184 110
`
`i __________________________________________ n 182
`
`116b_
`
`|
`
`r
`
`137
`
`140
`
`VIZIO EX. 1021
`
`K.J. Pretech Ex. 1021
`
`Pretech_000829
`
`

`
`5,828,488
`Page 2
`
`US. PATENT DOCUMENTS
`
`2/1971 Schrenk et al. ....................... .. 264/171
`3,565,985
`8/1971 Smith .................................... .. 250/199
`3,600,587
`3,610,729 10/1971 Rogers ..... ..
`.. 350/157
`3,647,612
`3/1972 Schrenk et al.
`.. 161/165
`3,711,176
`1/1973 Alfrey, Jr. et al.
`350/1
`3,746,485
`7/1973 Schrenk ................................ .. 425/131
`3,759,647
`9/1973 Schrenk etal. ....................... .. 425/131
`3,773,882 11/1973 Schrenk ....... ..
`.. 264/171
`3,801,429
`4/1974 Schrenk etal.
`.. 161/181
`3,847,585 11/1974 Chisholm ..... ..
`.. 65/99A
`4,025,688
`5/1977 Nagy etal. ........................... .. 428/350
`4,094,947
`6/1978 Alfrey, Jr. et al. ................... .. 264/171
`471907832
`2/1980 Mohler ~~~~~~~~~ n
`"
`4,212,048
`7/1980 Castleberry ............................. .. 362/19
`4,254,002
`3/1981 Sperling et al. .................. .. 260/23 ST
`4,268,127
`5/1981 Oshima etal.
`.. 350/337
`4,310,584
`1/1982 Cooper et al. ........................ .. 428/212
`4,315,258
`2/1982 McKnight et al. ................... .. 340/784
`474277741
`1/1984 Aizawa et a1'
`N 428632
`4,446,305
`5/1984 Rogers etal. ........................ .. 528/348
`4,520,189
`5/1985 Rogers etal. ........................ .. 528/331
`4,521,588
`6/1985 Rogers et al.
`.. 528/363
`4,525,413
`6/1985 Rogers et al. ........................ .. 428/212
`4,540,623
`9/1985 Im etal. ............................... .. 428/220
`475427449
`9/1985 Whitehead _
`_
`4,586,790
`5/1986 Umeda etal. ........................ .. 350/337
`4,590,119
`5/1986 Kawakamietal. .................. .. 428/216
`476437529
`2/1987 Hosonuma et a1‘
`__
`4,659,523
`4/1987 Rogers etal. ......................... .. 264/1.3
`4,660,936
`4/1987 Nosker .............................. .. 350/339 D
`4,678,285
`7/1987 Ohta et al.
`.. 350/345
`4,756,953
`7/1988 Utsumi .................................. .. 428/220
`4,791,540 12/1988 Dreyer, Jr. et al. ................... .. 362/331
`4,796,978
`1/1989 Tanaka etal.
`.. 350/337
`4,798,448
`1/1989 van Raalte ............................ .. 350/345
`4,799,772
`1/1989 Utsumi .............................. .. 350/339R
`4,805,984
`2/1989 Cobb, Jr. ...... ..
`.. 350/96.28
`4,824,882
`4/1989 Nakamura etal. ..................... .. 524/89
`478407463 @1989 Clark et a1‘ ~~~~~~~~~~~~~~~~~~~~~~~~ __ 350650 S
`478837341 11/1989 Whitehead
`_ 350076 R
`
`
`
`4,896,942 4,896,946
`
`
`
`1/1990 OIlStOtt et al. . 1/1990 Suzuki et al. ..
`
`
`
`. 350/96.33 .. 350/336
`
`3/1990 o1son etal.
`4,906,068
`4/1990 Conner et al. .
`4,917,465
`6/1990 Schrenk etal.
`4,937,134
`8/1990 Bradshaw et al.
`4,952,023
`4,974,946 12/1990 Solomon ...... ..
`4,989,076
`1/1991 OWada et al. .
`5,009,472
`4/1991 Morimoto ..
`5,042,921
`8/1991 Sato et al.
`5,056,888 10/1991 Messerly etal. .
`5,056,892 10/1991 Cobb, Jr. ......... ..
`5,059,356 10/1991 Nakamura et al.
`5,061,050 10/1991 Ogura ........... ..
`5,089,318
`2/1992 Shetty et al.
`5,093,739
`3/1992 Aida et al.
`5,094,788
`3/1992 Schrenk et al.
`5,094,793
`3/1992 Schrenk et al.
`570957210
`3/1992 Wheatley et aL
`571037337
`4/1992 Schrenk et a1_
`5,122,905
`6/1992 Wheatley et al.
`5,122,906
`6/1992 Wheatley ---- --
`
`--------
`
`. 350/96.3
`.. 350/335
`.. 428/213
`.. 350/102
`.. 350/399
`358/61
`350/6.5
`359/40
`.. 385/123
`.. 359/831
`252/585
`359/490
`428/212
`359/73
`264/171
`264/171
`250/339
`359/359
`359/586
`359/586
`
`7/1992 Leniritezri
`
`Zr‘
`571347516
`'
`’
`’
`350/73
`8/1992 Arakawa
`5,138,474
`359/63
`8/1992 Okumura _____ n
`571397340
`428/213
`9/1992 Wheatley et al_
`571497578
`359/63
`5,157,526 10/1992 Kondo et a1_
`5,159,478 10/1992 Akiyama etal. ....................... .. 359/69
`
`350/301
`
`5,166,817 11/1992 Ota et al. ................................ .. 359/73
`5,189,538
`2/1993 Arakawa
`359/73
`5,194,975
`3/1993 Akatsuka et al. ....................... .. 359/73
`5,200,843
`4/1993 Karasawa er a1, ______________________ __ 359/40
`5,202,074
`4/1993 Schrenk etal.
`. 264/241
`5,202,950
`4/1993 Arego et al.
`385/146
`5,217,794
`6/1993 Schrenk ..
`428/220
`5,221,982
`6/1993 Paris --------- --
`359/93
`5,233,465
`8/1993 Wheatley er al-
`359/359
`5,234,729
`8/1993 Wheatley etal-
`428/30
`52377446 8/1993 Tékahashi
`350/359
`5,238,738
`8/1993 M1116?
`428/333
`572457456
`9/1993 YOShlmleta-
`359/73
`5,255,029 10/1993 Vogeley etal
`353/122
`5,262,894 11/1993 Wheatley et al.
`359/586
`572697995 12/1993 Ramanathan etal-
`264/171
`5,278,680
`1/1994 Karasawa etal
`359/40
`572787694
`1/1994 Whea?ey etal-
`359/359
`5,286,418
`2/1994 Nakamum 6‘ ‘1L
`252/585
`5,295,018
`3/1994 KOnuma 6‘ ‘1L ~~
`359/487
`5,303,083
`4/1994 Blanchard et al.
`.. 359/495
`5309422 5/1994 Kumkletal ~
`~~ 369/110
`5316703 5/1994 scllrenk
`264/1-3
`5,325,218
`6/1994 W916“ 6‘ ‘1L
`359/53
`359/41
`573337072
`7/1994 Wllle“ ------ -
`573377174
`8/1994 Wad.a.eta1'
`359/73
`5,339,179
`8/1994 Rudisillet al.
`359/49
`573397198
`8/1994 Whea?ey 6‘ al-
`-- 359/359
`5,345,146
`9/1994 KOFHCI‘ etal
`~ 315/1693
`5,359,691 10/1994 Tar et al.
`.. 385/146
`5,360,659 11/1994 Arends etal
`~~ 428/216
`5,381,309
`1/1995 3018mm‘
`~~ 362/31
`5389324 2/1995 Lew“ etal-
`264/171
`5422756 6/1995 Weber ~~~~~~~~~ ~~
`359/487
`5448404 9/1995 Schrenk etal-
`359/584
`5451449 9/1995 She/“Y etal
`428/195
`5486949 1/1996 Schrenk 6‘ al-
`359/498
`5540978 7/1996 Schrenk ~~~~~~ ~~
`428/212
`5,552,927
`9/1996 Whea?ey 6‘ ‘1L
`359/359
`575597634
`9/1996 Weber --------- --
`-- 359/638
`5,568,316 10/1996 Schrenk et al. ....................... .. 359/584
`B1 4,660,936
`1/1990 Nosker .............................. .. 350/339 D
`
`5/1992 Japan ............................. .. B02B 5/30
`4-141603
`7/1992 Japan .
`. G03B 21/14
`4-184429
`5288910 11/1993 Japan .
`G02B 5/18
`6-11607
`1/1994 Japan .
`G02B 5/18
`6222207 8/1994 Japan
`G02B 5/02
`2 052 779
`1/1981 United Kingdom
`.. G02F 1/133
`WO 91/09719
`7/1991 WIPO ............ ..
`. B29C 43/20
`WO 94/11776
`5/1994 WIPO
`G02F 1/1335
`WO 94/29765 12/1994 WIPO
`.. G02F 1/1335
`WO 95/17303
`6/1995 WIPO
`B32B 7/02
`WO 95/17691
`6/1995 WIPO
`G02B 5/30
`WO 95/17692
`6/1995 WIPO
`G02B 5/30
`WO 95/17699
`6/1995 WIPO ......................... .. G02F 1/1335
`
`OTHER PUBLICATIONS
`“
`_
`_
`Schrenk et al, Coextruded Elastorneric Optical Interference
`Filrn”, SPE Annual Technical Conference,Atlanta, Georgia,
`1703—7 (1988).
`Schenk et al, “Coextruder Infrared Re?ecting Filrns”, 7th
`Annual Meeting Polyrner Processing Society Hamilton,
`Ontano’ Canada (Apr' 1991) -
`-
`Schrenk, “New Developments in Coextrusron”, Advances In
`.
`.
`.
`Polyrner 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. 8A, pp. L997—999, Aug. 1995.
`
`Pretech_000830
`
`

`
`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., “Re?ectivity of Iridescent CoeXtruded Mul
`tilayered Plastic Films”, presented at the American Chemi
`cal Society Symposium on CoeXtruded Plastic Films, Fibers,
`Composites, Apr. 9—14, 1972.
`3M IR—Compatible Safelight Kit, Instruction Sheet
`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).
`
`Baba et al., “Optical anisotropy of stretched gold island
`?lms: experimental results”, Optics Letters, vol. 17, No. 8,
`Apr. 15, 1992.
`Weber, “Retrore?ecting Sheet PolariZer”, SID conf. pro
`ceedings, Boston, MA, May 1992, SID 92 Digest, pp.
`427—429.
`
`Weber, “Retrore?ective Sheet PolariZer”, SID conf. pro
`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 ?lms”,
`Optical Society ofAmeria, vol. 10, No. 9, pp. 2065—2071,
`Sep. 1993.
`Zang et al., “Giant Anistropies in the Dielectric Properties of
`Quasi—EpitaXial Crystalline Organic Semiconductor Thin
`Films”.
`
`Pretech_000831
`
`

`
`U.S. Patent
`
`Oct.27,1998
`Sheet 1 0f 32
`A
`/ w m
`
`5,828,488
`
`18
`
`,12
`
`\
`
`i
`
`62
`
`L64
`
`r37
`
`F24
`
`Fig. 1
`
`Fig. 2
`
`Pretech_000832
`
`

`
`U.S. Patent
`
`0a. 27, 1998
`
`Sheet 2 0f 32
`
`5,828,488
`
`17
`/ 18
`_/
`“R20
`
`(/12
`
`24
`
`119
`
`1
`
`21
`
`Fig. 3
`
`Pretech_000833
`
`

`
`U.S. Patent
`
`Oct.27,1998
`
`Sheet 3 0f 32
`
`5,828,488
`
`100
`
`I
`
`60'
`
`%T
`
`40"
`
`33
`
`400
`
`500
`
`600
`
`>\(nm)
`Fig. 5
`
`700
`
`Pretech_000834
`
`

`
`U.S. Patent
`
`0111.27, 1998
`
`Sheet 4 0f 32
`
`5,828,488
`
`\
`"
`\
`
`i
`
`\
`136
`
`113
`
`‘
`
`i
`
`165 4163
`
`JV
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`<5
`
`11o
`
`140
`/
`
`K
`
`Fig. 6
`
`224
`
`222
`
`Fig. 7
`
`Pretech_000835
`
`

`
`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 5 of 32
`
`5,828,488
`
`HEFLECTED
`
`age
`
`226
`
`00
`
`TRANSMITTED
`
`TRANSMITTED
`
`//£3
`
`94°
`
`9.4°
`
`33-4\\
`
`Fig. 8
`
`2(146
`
`164
`
`152 (a,c)
`
`148
`(a,b,c,d)
`
`150
`
`161(a)
`
`110
`’/
`
`154 (a,b,c,d)
`
`140
`
`156 (b,c,d)
`
`157 (a,b,c,d)
`
`9
`
`Pretech_000836
`
`Pretech_000836
`
`

`
`U.S. Patent
`
`0111.27, 1998
`
`Sheet 6 0f 32
`
`5,828,488
`
`146
`
`170<
`
`[f m m w W
`172
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`
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`
`[140
`
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`
`Pretech_000837
`
`

`
`U.S. Patent
`
`061. 27, 1998
`
`Sheet 7 0f 32
`
`5,828,488
`
`160-
`
`--L .p O
`
`
`
`Relative Brightness
`
`66 3 O O
`
`60
`
`40
`
`20
`
`00 5 1'0
`
`1'5 2'0 2'5 3'0 3'5 4'0 4'5 5'0 5'5 6'0 6'5 7'0
`Degrees off normal
`Fig. 12
`
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`/|\
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`
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`
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`
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`
`Pretech_000838
`
`

`
`U.S. Patent
`
`Oct.27,1998
`
`Sheet 8 0f 32
`
`5,828,488
`
`110 /
`
`Pretech_000839
`
`

`
`U.S. Patent
`
`Oct.27,1998
`
`Sheet 9 0f 32
`
`5,828,488
`
`no
`
`n2y
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`———>-
`
`no
`
`102
`
`104
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`
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`
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`
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`X
`Fig. 15
`
`Pretech_000840
`
`

`
`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 10 0f 32
`
`5,828,488
`
`f0
`
`rm \Q
`
`f
`
`0.05?
`
`0.04
`
`0.03 -
`
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`
`0.01 -
`
`REFLECTIVITY
`
`0
`0
`
`l
`
`I
`
`I
`
`l
`
`1O 20 30 40 50 60 70 80 90
`
`I
`
`I
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`
`ANGLE OF INCIDENCE IN 1.60 MEDIUM
`Fig. 16
`
`0.05?
`
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`
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`
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`
`0.01
`
`FIEFLECTIVITY
`
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`10 20 30 40 50 60 70 80 90
`
`ANGLE OF INCIDENCE IN 1.60 MEDIUM
`Fig. 17
`
`Pretech_000841
`
`

`
`U.S. Patent
`
`Oct.27,1998
`
`Sheet 11 0f 32
`
`5,828,488
`
`0.012 —
`
`a _ H _ a
`
`0. o 0. 0 0.
`m w m M m o
`O 0 0 O
`
`EZBwiwm
`
`O
`
`10 2O 3O 4O 50 6O 70 80 9O
`
`ANGLE OF INCIDENCE IN 1.00 MEDIUM
`
`INDEX
`A
`
`IN-PLANE
`INDEX 1
`
`lN-PLANE
`INDEX 2
`ISOTROPIC
`CASE
`
`\
`INCREASING
`N0 BREWSTER ANGLE,
`BREWSTER .
`ANGLE
`: R INCREASES WITH ANGLE
`
`Fig. 19
`
`NO BREWSTER ANGLE,
`R CONSTANT
`
`Pretech_000842
`
`

`
`U.S. Patent
`
`0a. 27, 1998
`
`Sheet 12 0f 32
`
`5,828,488
`
`INDEX
`A
`
`lN-PLANE/
`
`INDEX 1
`
`ISOTFIOPIC
`CASE
`
`IN~PLANE
`INDEX 2
`
`n22
`
`INDEX
`‘ IN-PLANE
`INDEX 1
`
`DECREASING
`BREWSTER
`ANGLE
`
`Fig. 20
`
`lN-PLANE
`INDEX2
`
`ISOTFIOPIC
`CASE
`
`=
`I
`.
`'
`
`INCREASING
`BREWSTER
`ANGLE
`Fig. 21
`
`N0
`RlNcREAéEs
`WITH ANGLE
`
`,
`
`Pretech_000843
`
`

`
`0a. 27, 1998
`
`Sheet 13 0f 32
`
`5,828,488
`
`U.S. Patent
`1.0
`
`0.8-
`
`MM 400
`
`650
`
`700
`
`450
`
`600
`550
`500
`WAVELENGTH (nm)
`Fig. 22
`
`0.0001 H
`
`0.00008 —
`
`0.00006 —
`
`0.00004 —
`
`0.00002 4
`
`REFLECTIVITY
`
`0
`
`0
`
`l
`I
`l
`I
`I
`I
`l
`l
`I
`10 20 30 40 50 60 70 80 9O
`ANGLE OF INCIDENCE IN 1.00 MEDIUM
`Fig. 23
`
`Pretech_000844
`
`

`
`U.S. Patent
`
`0a. 27, 1998
`
`Sheet 14 0f 32
`
`5,828,488
`
`0.0001 -
`
`0.00008 '
`
`0.00006 -
`
`0.00004 —
`
`0.00002—
`
`REFLECTIVITY
`
`°
`
`0
`I
`I
`I
`I
`I
`I
`I
`I
`I
`010 20 3040 50 6070 80 9
`
`ANGLE OF INCIDENCE IN 1.00 MEDIUM
`Fig. 24
`
`Pretech_000845
`
`

`
`U.S. Patent
`
`0a. 27, 1998
`
`Sheet 15 0f 32
`
`5,828,488
`
`002
`
`0.01~
`
`>
`C
`<1
`
`0~
`
`-0.01~
`
`-O'02— 1
`
`l
`
`l
`
`-0.075 -0.05 -0.025
`
`l
`
`0
`
`l
`
`l
`
`1
`
`0.025
`
`0.05 0.075
`
`a
`
`Anz
`
`Fig. 25
`
`Pretech_000846
`
`

`
`U.S. Patent
`
`0a. 27, 1998
`
`Sheet 16 0f 32
`
`5,828,488
`
`100 -
`
`8O -
`
`60 "
`
`% Transmission
`
`40
`
`20 '
`
`O
`400
`
`l
`450
`
`i
`l
`2
`600
`550
`500
`Wave Length (nm)
`Fig. 26
`
`E
`650
`
`i
`700
`
`Pretech_000847
`
`

`
`U.S. Patent
`
`0a. 27, 1998
`
`Sheet 17 0f 32
`
`5,828,488
`
`100 '
`
`20 '
`
`400
`
`450
`
`600
`500
`550
`Wave Length (nm)
`Fig. 27
`
`650
`
`700
`
`Pretech_000848
`
`

`
`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 18 of 32
`
`5,828,488
`
`100
`
`80
`
`60
`
`40
`
`20
`
`°/oTransmission
`
`450
`
`500
`
`550
`
`600
`
`650
`
`700
`
`0 4
`
`00
`
`Wave Length (nm)
`Fig. 28
`
`Pretech_000849
`
`Pretech_000849
`
`

`
`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 19 of 32
`
`5,828,488
`
`100
`
`80
`
`%Transmission
`
`20
`
`1
`
`400
`
`500
`
`600
`
`700
`
`800
`
`900
`
`1000
`
`1100
`
`Wave Length (nm)
`
`Fig. 29
`
`Pretech_000850
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`Pretech_000850
`
`

`
`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 20 of 32
`
`5,828,488
`
`100
`
`O)O%Transmission
`
`43-O
`
`20
`
`400
`
`450
`
`500
`
`550
`
`600
`
`650
`
`700
`
`Wave Length (nm)
`
`Fig. 30
`
`Pretech_000851
`
`Pretech_000851
`
`

`
`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 21 of 32
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`5,828,488
`
`b
`
`a
`
`400
`
`500
`
`600
`
`700
`
`800
`
`Wave Length (nm)
`
`Fig. 31
`
`10
`
`8
`
`C
`
`.9
`.3 5
`
`E 2 E
`
`r— 4
`
`o\°
`
`2
`
`Pretech_000852
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`Pretech_000852
`
`

`
`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 22 of 32
`
`5,828,488
`
`100
`
`80
`
`a
`
`60%Transmission
`
`20
`
`400
`
`500
`
`600
`
`700
`
`800
`
`Wave Length (nm)
`Fig. 32
`
`Pretech_000853
`
`Pretech_000853
`
`

`
`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 23 of 32
`
`5,828,488
`
`100
`
`80
`
`60
`
`40%Transmission
`
`20
`
`400
`
`500
`
`600
`
`700
`
`800
`
`Wave Length (nm)
`
`Fig. 33
`
`Pretech_000854
`
`Pretech_000854
`
`

`
`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 24 of 32
`
`5,828,488
`
`100
`
`80
`
`60
`
`40%Transmission
`
`20
`
`400
`
`500
`
`600
`
`700
`
`800
`
`Wave Length (nm)
`
`Fig. 34
`
`Pretech_000855
`
`Pretech_000855
`
`

`
`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 25 of 32
`
`5,828,488
`
`100
`
`80
`
`60
`
`20
`
`°/oTransmission
`
`400
`
`500
`
`600
`
`700
`
`800
`
`Wave Length (nm)
`
`Fig. 35
`
`Pretech_000856
`
`Pretech_000856
`
`

`
`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 26 of 32
`
`5,828,488
`
`100
`
`80
`
`60%TRANSMISSION
`
`20
`
`400
`
`5 8
`
`7 600
`
`700
`
`300
`
`WAVE LENGTH (nm)
`
`Fig. 36
`
`Pretech_000857
`
`Pretech_000857
`
`

`
`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 27 of 32
`
`5,828,488
`
`
`
`
`
`WAVELENGTH(nm) Fig.37
`
`800
`
`700
`
`500600
`
`Pretech_000858
`
`Pretech_000858
`
`

`
`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 28 of 32
`
`5,828,488
`
`100
`
`90
`
`a
`
`%TRANSMISSION
`
`0 ,_,
`
`4oo
`
`500
`
`eoo
`
`7oo
`
`soo
`
`WAVE LENGTH (nm)
`
`Fig. 33
`
`Pretech_000859
`
`Pretech_000859
`
`

`
`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 29 of 32
`
`5,828,488
`
`100
`
`80
`
`O)O%TRANSMISSION 4so
`
`20
`
`400
`
`500
`
`600
`
`700
`
`800
`
`WAVE LENGTH (nm)
`
`Fig. 39
`
`Pretech_000860
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`Pretech_000860
`
`

`
`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 30 of 32
`
`5,828,488
`
`100
`
`80
`
`b
`
`a
`
`C
`
`500
`
`600
`
`700
`
`800
`
`Wave Length (nm)
`
`Fig. 40A
`
`S
`'7: 60
`.2
`E(D
`
`C E
`
`}—
`8 4o
`
`20
`
`O
`400
`
`Pretech_000861
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`Pretech_000861
`
`

`
`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 31 of 32
`
`5,828,488
`
`100
`
`80
`
`%Transmission88
`
`20
`
`0
`400
`
`Pretech_000862
`
`O
`
`500
`
`600
`
`700
`
`800
`
`Wave Length (nm)
`Fig. 40B
`
`Pretech_000862
`
`

`
`U.S. Patent
`
`Oct. 27, 1998
`
`Sheet 32 of 32
`
`5,828,488
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`100
`
`80
`
`“L
`
`b
`
`a
`
`S
`‘:7: 60
`.1’
`EU)
`
`C EI
`
`-
`
`c
`
`500
`
`600
`Wave Length (nm)
`
`700
`
`800
`
`Fig. 40C
`
`o\° 40
`
`20
`
`0
`400
`
`Pretech_000863
`
`Pretech_000863
`
`

`
`1
`REFLECTIVE POLARIZER DISPLAY
`
`2
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`5,828,488
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS
`
`This is a continuation in part of U.S. patent application 5
`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.
`
`10
`
`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
`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-
`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-
`tation more strongly than the orthogonal polarization orien-
`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-
`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
`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
`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-
`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.
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`The drawings depict representative and illustrative imple-
`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
`
`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-
`ness enhancer;
`FIG. 8 is a graph illustrating the operation of a brightness
`enhancer;
`FIG. 9 is a schematic cross section of an illustrative
`
`optical display;
`FIG. 10 is a schematic cross section of an illustrative
`
`optical display;
`FIG. 11 is a schematic cross section of an illustrative
`
`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
`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
`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
`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-
`ence in a biaxial birefringent film with a large z-index
`difference.
`
`FIG. 24 shows the effect of introducing a y-index differ-
`ence in a biaxial birefringent film with a small z-index
`difference.
`
`FIG. 25 shows a contour plot summarizing the informa-
`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
`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
`polarizer given in Example 13;
`FIG. 39 shows optical performance of the polarizer given
`in Example 14; and
`
`Pretech_000864
`
`Pretech_000864
`
`

`
`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-
`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
`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
`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
`referred to as “(a)” and effectively reflects light having the
`orthogonal polarization orientation
`Consequently, a cer-
`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
`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
`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
`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-
`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-
`tion exhibited by the reflective polarizer disclosed herein
`and the high reflectivity and randomizing properties exhib-
`ited by many diffusely reflective surfaces. In FIG. 2 both the
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`4
`discontinuous layer depicted by spot 36 and the diffusely
`reflective continuous layer 39 may be formed of a titanium
`oxide pigmented material. It should be appreciated that a
`diffuse reflective surface 37 (shown in FIG. 1) can be formed
`of transparent surface textured polycarbonate. This material
`could be placed above the light guide 34 to randomize
`incident light in the configuration shown in FIG. 2. The
`specific and optimal configuration will depend on the par-
`ticular application for the completed optical display.
`In general, the gain of the system is dependent on the
`efficiency of both the reflective polarizer body 12 and the
`optical cavity 24. Performance is maximized with a highly
`reflective optical cavity 24 consistent with the requirement
`of randomization of the polarization of incident light, and a
`very low loss reflective polarizer 12.
`FIG. 3 shows a schematic optical display 14 illustrated
`with a two layer LCD assembly 17 that includes a front
`polarizer 18 and a liquid crystal 20. In this embodiment the
`optical cavity 24 includes an electroluminescent panel 21.
`The traditional electroluminescent panel 21 is coated with a
`phosphor material 19 that generates light when struck by
`electrons and that is also diffusely reflective when struck by
`incident
`light. Usually, electroluminescent displays are
`“grainy” because of the variations in efficiencies associated
`with the phosphor coating. However, light returned by the
`reflective polarizer 12 has a tendency to “homogenize” the
`light emissions and improve overall uniformity of illumina-
`tion exhibited by the optical display 14. In the illustrative
`optical display 14 the LCD assembly 17 lacks a rear polar-
`izer. In this optical display 14 the reflective polarizer 12
`performs the function normally associated with the rear
`polarizer 23 shown in optical display 11 in FIG. 2.
`FIG. 4 is a schematic perspective diagram of a segment of
`the reflective polarizer 12. The figure includes a coordinate
`system 13 that defines X, Y and Z directions that are referred
`to in the description of the reflective polarizer 12.
`The illustrative reflective polarizer 12 is made of alter-
`nating layers (ABABA .
`.
`. ) of two different polymeric
`materials. These are referred to as material “(A)” and
`material “(B)” throughout the drawings and description. The
`two materials are extruded together and the resulting mul-
`tiple layer (ABABA. .
`. ) material is stretched (5:1) along
`one axis (X), and is not stretched appreciably (1:1) along the
`other axis
`The X axis is referred to as the “stretched”
`direction while the Y axis is referred to as the “transverse”
`direction.
`
`index of refraction
`The (B) material has a nominal
`(n=1.64 for example) which is not substantially altered by
`the stretching process.
`The (A) material has the property of having the index of
`refraction altered by the stretching process. For example, a
`uniaxially stretched sheet of the (A) material will have one
`index of refraction (n=1.88 for example) associated with the
`stretched direction and a different
`index of refraction
`
`(n=1.64 for example) associated with the transverse direc-
`tion. By way of definition, the index of refraction associated
`with an in-plane axis (an axis parallel to the surface of the
`film) is the effective index of refraction for plane-polarized
`incident light whose plane of polarization is parallel to that
`axis.
`
`Thus, after stretching the multiple layer stack
`(ABABA .
`.
`. ) of material shows a large refractive index
`difference between layers (delta n=1.88—1.64=0.24) associ-
`ated with the stretched direction. While in the transverse
`
`direction, the associated indices of refraction between layers
`are essentially the same (delta n=1.64—1.64=0.0). These
`
`Pretech_000865
`
`Pretech_000865
`
`

`
`5,828,488
`
`5
`optical characteristics cause the multiple layer laminate to
`act as a reflecting polarizer that will transmit the polarization
`component of the incident l