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`5，944，405
`[11] Patent Number:
`[45] Date of Patent: *Aug. 31，1999
`
`I l ----------ー----------I l ----------ー----------I l ----------ー----------l i l ----------ー
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`US005944405A
`
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`
`ー
`
`United States Patent [19]
`Takeuchi et al.
`
`[54] FLAT LIGHT SOURCE USING LIGHT-
`DIFFUSING SHEET WITH PROJECTIONS
`THEREON
`
`[75] Inventors: Michiko Takeuchi; Toshikazu Nishio;
`Ta羽iIshii， all of Tokyo-To， Japan
`
`[73] Assignee: Dai Nippon Printing Co.， Ltd.， Japan
`
`[ *] Notice・ Thispatent issued on a continued pros-
`ecution application filed under 37 CFR
`1.53( d)， and is subject to the twenty year
`patent term provisions of 35 U.S.c.
`154(a)(2).
`08/619，623
`[21] Appl. No.:
`[22] PCT Filed: Aug. 11， 1995
`
`[86] PCT No.:
`PCT/JP95/01608
`~ 371 Date: May 30， 1996
`~ 102(ι) Date: May 30， 1996
`
`[87] PCT Pub. No.: W096/05466
`PCT Pub. Date: Feb. 22， 1996
`
`[30]
`
`Foreign Application Priority Data
`
`Aug. 12タ 1994 [JP] Japan ...........・ H ・...・ H ・H ・H ・........6-210694
`
`[51] Int. CI.6
`........................................................ F21 V 7/04
`[52] U.S. CI. .....………・………....362/31; 362/551
`[58] Field of Search .....………… 362/26， 31， 551
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`4タ729タ067 3/1988 Ohe ........................................... 362/26
`4タ729タ068 3/1988 Ohe….....・ H ・.........・ H ・.....・ H ・.........362/26
`4タ775タ222 10/1988 Ohe …・・…...・ H ・......・ H ・........・ H ・......362/26
`4タ998タ804 3/1991 Horiuchi ..………….... 362/26
`5タ262タ928 11/1993 Kashima et al. ・・・・ H ・H ・.........・ H ・...362/26
`5タ289タ351 2/1994 Kashima et al. ...・ H ・H ・H ・...・ H ・......362/26
`5タ408タ388 4/1995 Kobayashi et al.…・……..362/26
`5タ442タ523 8/1995 Kashima et al. ...・ H ・H ・H ・......・ H ・...362/26
`5タ467タ208 11/1995 Kokawa et al. ...・ H ・.....・ H ・...・ H ・...362/26
`5タ467タ417 11/1995 Nakamura et al.……........ 362/26
`
`5タ521タ725 5/1996 Beeson et al.………...・ H ・.....・ H ・...362/26
`5タ521タ797 5/1996 Kashima et al. ...・ H ・...・ H ・.....・ H ・...362/26
`5タ572タ411 11/1996 Watai et al.…・…………..362/31
`5タ598タ280 1/1997 Nishio et al. ...・ H ・.........・ H ・.........362/31
`5タ641タ219 6/1997 Mizobe ・・・・ H ・H ・.....・ H ・.........・ H ・.....362/26
`
`FOREIGN PATENT DOCUMENTS
`
`55-162201 9/1980 Japan.
`61-55684 3/1986 Japan.
`62-3226 1/1987 Japan.
`1-112202 4/1989 Japan.
`1-245220 9/1989 Japan.
`3-9306 1/1991 Japan.
`4-107201 9/1992 Japan.
`5-196940 8/1993 Japan.
`6-15008 2/1994 Japan.
`
`Primary Examiner-Sandra O'Shea
`Assistant Examiner---Marshall Honeyman
`Attorney， Agent， or Firmー-Parkhurst& Wendel LLP
`
`[57]
`
`ABSTRACT
`
`A fiat light source used as back-lighting for a liquid crystal
`display device includes an optically conductive plate (1)
`having a light refiecting layer (2)， and a light source (3). A
`light-di旺usingsheet (8) is provided outside the optically
`conductive plate (1) oppos山 tothe light refiecti昭 layer(2)
`A lens sheet (4) is provided outside the light-diffusing sheet
`(8)， with a transmission type of display element (6) provided
`on the outer side of the lens sheet (4). The light-diffusing
`sheet (8) is formed of a transparent material free from
`light-diffusing agent particles and has minute irregularities
`(41) formed at random on the front surfa∞ thereof. The
`irregularities are of a surface roughness that is at least the
`wavelength of the light from the light source， but is no more
`than 100μm. When the percentage of the cumulative fre-
`quency distribution of the heights of the minute irregularities
`are plotted along the Y-紅 白 andthe heights of these minute
`irregularities are plotted along the X-axis， the cumulative
`frequency distribution curve has a convex portion oriented
`towards the lower side of the coordinates and the average
`value of the heights of the minute irregularities is greater
`than the median value thereof. Thus， a fiat light source is
`provided which emits highly luminant light uniformly
`within a predetermined angular range， and which has no
`local di旺erencesin intensity over the surface thereof.
`
`11 Claims， 20 Drawing Sheets
`
`'CO~f
`
`1ム
`
`Sony Corp. Exhibit 1023
`
`SONY_000941
`
`

`
`u.s. Patent
`
`Aug. 31，1999
`
`Sheet 1 of 20
`
`5，944，405
`
`6
`
`100
`
`6
`
`100
`
`2
`10
`F I G. I
`
`\ / ，/ L /
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`\ !壬、.へ"，...--:-
`\ I( γ 3 3 tγ /
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`に一一一一一一一一一一一一一 J
`
`F I G. 2
`
`SONY_000942
`
`

`
`u.s. Patent
`
`Aug. 31，1999
`
`Sheet 2 of 20
`
`5，944，405
`
`42υυ
`
`F I G. 3
`
`42
`
`41
`
`F I G. 4
`
`SONY_000943
`
`

`
`u.s. Patent
`
`Aug. 31，1999
`
`Sheet 3 of 20
`
`5，944，405
`
`42
`
`42
`
`42
`
`F I G. 5
`
`F I G. 6
`
`F I G. 7
`
`4 /
`
`42
`
`F I G. 8
`
`4
`
`SONY_000944
`
`

`
`u.s. Patent
`
`Aug. 31，1999
`
`Sheet 4 of 20
`
`5，944，405
`
`両λ工
`
`10
`
`/
`/
`/
`
`\/\ 、、L
`FIG.9
`
`1R
`
`ジ9
`
`10
`
`FIG. 10
`
`FIG. 11
`
`4
`
`8
`
`9--
`
`SONY_000945
`
`

`
`u.s. Patent
`
`Aug. 31，1999
`
`Sheet 5 of 20
`
`5，944，405
`
`23~
`
`ザ 23
`
`I I
`
`F I G. 12
`
`8
`
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`
`.町田'ー
`
`ロ 引 ロ
`
`F I G. 13
`
`SONY_000946
`
`

`
`u.s. Patent
`
`Aug. 31，1999
`
`Sheet 6 of 20
`
`5，944，405
`
`FIG. 14 PRIORART
`
`Y
`
`4
`.100
`
`FIG. 15 PRIOR ART
`
`FIG. 16 PRIOR ART
`
`SONY_000947
`
`

`
`u.s. Patent
`
`Aug. 31，1999
`
`Sheet 7 of 20
`
`5，944，405
`
`(0/0)
`
`zo一
`
`CURVE fA(R}
`
`o nv
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`
`SURFACE
`
`ROUGHNESS
`
`RMAX
`
`F I G.
`
`17
`
`F I G.
`
`18
`
`みみら
`
`F I G.
`
`19
`
`みみみ
`
`F I G.
`
`20
`
`SONY_000948
`
`

`
`u.s. Patent
`
`Aug. 31，1999
`
`Sheet 8 of 20
`
`5，944，405
`
`CUMULATIVE
`FREQUENCY
`DISTR旧UTION (%)
`
`0
`100
`
`HEIGHT OF
`IRREGULARITIES
`( ABSOLUTE VALUE )
`57.7 (μm)
`
`28.8
`
`AVERAGE 50
`VALUE
`
`。
`
`MINIMUM
`VALUE
`
`50
`MEDIAN
`VALUE
`
`100 (0/0)
`HEIGHT OF
`IRREGULARITIES
`(ABSOLUTE VALUE)
`
`F I G. 2 I
`
`SONY_000949
`
`

`
`5，944，405
`
`o-
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`
`ヲL-FE
`
`白リ
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`AOg. 31， 1999
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`
`(cid:631)ムI
`
`サ
`
`SONY_000950
`
`

`
`u.s. Patent
`
`Aug. 31，1999
`
`Sheet 10 of 20
`
`5，944，405
`
`CUMULATIVE
`FREQUENCY
`DISTR旧UTION (%)
`
`0
`100
`
`HEIGHT OF
`IRREGULARITIES
`( ABSOLUTE VALUE)
`6.88 (μm)
`
`3.44
`
`AVERAGE 50
`VALUE
`
`。
`
`MINIMUM
`VALUE
`
`50
`MEDIAN
`VALUE
`
`100 (0/0 )
`HEIGHT OF
`IRREGULARITIES
`( ABSOLUTE VALUE)
`
`F I G. 23
`
`SONY_000951
`
`

`
`u.s. Patent
`
`Aug. 31，1999
`
`Sheet 11 of 20
`
`5，944，405
`
`寸N
`
`
`
`.0-L
`
`oom一N .00一一〉
`
`00一一 X ZO一トdo--比一ア一042
`
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`
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`
`SONY_000952
`
`

`
`u.s. Patent
`
`Aug. 31，1999
`
`Sheet 12 of 20
`
`5，944，405
`
`CUMULATIVE
`FREQUENCY
`DISTRI8UTION (%)
`
`0
`100
`
`HEIGHT OF
`IRREGULARITIES
`( A8S0LUTE VALUE )
`21.3 (μm)
`
`10.6
`
`AVERAGE 50
`VALUE
`
`。
`
`MINIMUM
`VALUE
`
`50
`MEDIAN
`VALUE
`
`100 ( % )
`
`HEIGHT OF
`IRREGULARITIES
`(A8S0LUTE VALUE )
`
`F I G. 25
`
`SONY_000953
`
`

`
`u.s. Patent
`
`Aug. 31，1999
`
`Sheet 13 of 20
`
`5，944，405
`
`<D
`N
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`
`SONY_000954
`
`

`
`u.s. Patent
`
`Aug. 31，1999
`
`Sheet 14 of 20
`
`5，944，405
`
`CUMULATIVE
`FREQUENCY
`DISTRIBUTION (%)
`
`0
`100
`
`HEIGHT OF
`IRREGULARITIES
`(ABSOLUTE VALUE )
`20.3 (μm)
`
`10.1
`
`AVERAGE
`VALÜÈ~~ 50
`
`。
`
`MINIMUM
`VALUE
`
`50
`MEDIAN
`VALUE
`
`100 (0/0)
`HEIGHT OF
`IRREGULARITIES
`(ABSOLUTE VALUE)
`
`F I G. 27
`
`40μm
`
`41
`
`12
`
`F I G. 28
`
`SONY_000955
`
`

`
`u.s. Patent
`
`Aug. 31，1999
`
`Sheet 15 of 20
`
`5，944，405
`
`CUMULATIVE
`FREQUENCY
`DISTRIBUTION (%)
`
`0
`100
`
`HEIGHT OF
`IRREGULARITIES
`(ABSOLUTE VALUE )
`4，10 (μm)
`
`2.02
`
`AVERAGE 50
`VALUE
`
`。
`
`MINIMUM
`VALUE
`
`50
`MEDIAN
`VALUE
`
`100 (0/0)
`
`HEIGHT OF
`IRREGULARITIES
`(ABSOLUTE VALUE)
`
`F I G. 29
`
`SONY_000956
`
`

`
`u.s. Patent
`
`Aug. 31，1999
`
`Sheet 16 of 20
`
`5，944，405
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`SONY_000957
`
`

`
`u.s. Patent
`
`Aug. 31，1999
`
`Sheet 17 of 20
`
`5，944，405
`
`CUMULATIVE
`FREQUENCY
`DISTR旧UTION (%)
`
`0
`100
`
`HEIGHT OF
`IRREGULARITIES
`( ABSOLUTE VALUE )
`3.06
`
`1.53
`
`AVERAGE 50
`VALUE
`
`。
`
`MINIMUM
`VALUE
`
`50
`MEDIAN
`VALUE
`
`100 (010 )
`HEIGHT OF
`IRREGULARITIES
`(ABSOLUTE VALUE)
`
`F I G. 3 I
`
`SONY_000958
`
`

`
`u.s. Patent
`
`Aug. 31，1999
`
`Sheet 18 of 20
`
`5，944，405
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`
`u.s. Patent
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`Aug. 31，1999
`
`Sheet 19 of 20
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`5，944，405
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`

`
`u.s. Patent
`
`Aug. 31，1999
`
`Sheet 20 of 20
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`5，944，405
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`
`5ラ944ラ405
`
`2. An attempt to correct and make uniform the luminance
`
`o
`
`TECHNI CAL FIELD
`
`BACKGROUND OF THE INVENTION
`
`1
`FLAT LIGHT SOURCE USING LIGHT-
`DIFFUSING SHEET WITH PROJECTIONS
`THEREON
`
`2
`imposed on the light-emitting surface of the optically con-
`ductive plate as the lens sheet， the ratio of optical energy
`emitted within angles between 30 and 60 degrees from the
`normal to the light-emitting surface is comparatively high，
`5 but even if the portion within 2 to 4 cm of the side edge
`portion of the optically conductive plate is very bright， the
`The present invention relates to a fiat light source that can
`luminan∞drops gradually further away from this portion so
`be used in applications such as back-lighting for a light
`that the edge at the opposite side from the light source is
`transmissive type of display device such as a liquid crystal
`noticeably darker.
`display device， an illuminated advertisement， or a traffic
`10 If a frosted transparent scattering diffusion plate is used，
`sign. In particular， it relates to a fiat light sourc芯 thatuses a
`a further problem arises in that the particles oflight-diffusing
`light-di旺usingsheet.
`agent within the optically conductive plate absorb some of
`the light， so that the optical energy thereof is lost.
`In addition， interference patterns such as Newton's rings
`Flat light sources that are used for back-lighting in 15 could be generated by the optical seal between the lens sheet
`devices such as 1叩 lidcrystal d岬 lays(LCDs) are known in and the s~rface of the opti~ally conductive plate.
`the art， as described below.
`Techniques that have been tried to solve these problems
`Afirst known type of fiat light source is an edge-lit system include:
`that uscs a Hat optically transmissivcplatcas an opticallY201.An attcmpt to corrcct and makcuniform thcluminancc
`conduct1vcmcmbcr.R16Hat light sourccuscd in thIs systcm distribution within thcSUrfaccof thcoptically conductivc
`causcs light to bcmcidGIlt on oncor both sidccdgcSUrfaccs platcby crcating a pattcrn1n a 11ght-scattcrIIlg rcncctivc
`of thcoptically conductimmcmbcr which is formcd of a laycr on thcrcar SUrfaccof thCoptICally conductivcplatc，
`transparcnt Hat platc.Total rcHCCHon within thGHat optically such as a dot pattcrn，in such a manncr that thcSUrfaccarca
`transmissivcplatciS11t1lizcd to propagatcthclight through-of thcpattcrn is dccrcascd closcr to thclight sourccand
`out thccnt1rcoptically conductivcplatcPart of thcthus25incrcascd hlrthcr away thcrcfrom，as discloscd in Japancsc
`propagatcd lIght bCCOIncs diEuscd rcncctcd lIght of lcss than patGIlt La1d-OPGIINo.1-245，220and JapancSCUtility Modcl
`thccritical anglcfrom a light-scattcring rcncctivcplatcon Laid-OPGIINo.645，O08.
`the rear surface of the optically conductive plate， and thus
`diffused light is emitted from the outer surface of the
`O叩p戸戸tic刷iたc
`Laid Opια叩In1No 55462，2 0 1 ) p o r t I o n s of thcoptically coMMMplatc，as discloscd in
`A s~cond kno::vn t~pe of ~at ~ight so~r~e ha~ a lensshe~t j apa田 sePatent Laid-Open No. 3-9306
`
`wherein one su巾 cehas p叫 ectionsand the other su巾 celS
`3. A畑na山tt旧t民ι悶m叫pt凶tω00伽bta削m a吋di附r
`smooth，which is placcd with thcprojCCHon sidcthcrCOI on35substantially uniform luminanccfrom thcGIltircSUrfaccof
`the ou町 surfaceof批 opticallyconductお~ ~late?f the_~at ~~ th~ o~-ti~~ii~ c~~d~~~i~~-;i~t~， b~- ;;~viding a li醐 rpris-
`matic array (an array of prism;ti~ lens吋 thatpartiall y
`ligl山 ourceofthe above first type. The light-focusi昭氏~~o~
`of this lens is utilized to ensure that the di旺used，refiected refiects and partially passes light on either the front or rear
`light is diffused unifor守ly_and i~otropicallywithin a pr~de-
`su巾 ∞ ofthe optically conductive plate， and varying the
`tcmmcd angularranptrckrtoJapancscut出 tyModel Laid 40 a昭 leof inclination of the su巾 cesof tl同 己 prismsand
`'" l~~;lly~;;~i~~ th~- thicb;ess ~f the ~;tically r;~~d~ctive
`Open No. 4-107，201).
`The above described lens sheet could be used in combi- plate， as disclosed in Japanese Patent Laid-Open No.
`nation with a frosted transparent diffusion plate (a frosted 62-3226
`transparcnt shcct)formcd by dispcrsing partiCIGs of a light-AIl of thGabOVGIncaS11rcs，and othcrs，havcproblcmS in
`ditrusing agcnt such as Ti02within a transparcnt plastic.In 45that it is dimcult to prOvidca complctcly uniform luminancc
`such a case， the optical energy of the light source is th灯 油y.In addition， technique 1 has a further problem in
`dmtrIb11tcdm a morCCOIlCGIltratcd manncr WIth1n a prcdc-that thcdot pattcrn of thclidlt-scattcring rcncct1vclayGr is
`tcrmiI16d limitcd angular rangc，than whcn a frostcd trans-viS1blcfrom thcsidcfrom which 11dltmcm1ttcd TcchI11q116
`parcnt diE11Sion platcaloI16is placcd ovcr thcopticallY2has a f11rthcr problcm in that thcspaccrcq11ircd for thc
`conductivcplatc(rcfcr to U.s.Pat.No.4，729，O67and 506ntirclight sourccand thcpowcr consumption thcrcof arc
`Japanese Patent Laid Open No. 61-55，684). Moreover， a more th;~ doubled.
`uniform and highly isotropic diffused light can be obtained
`Technique 3 has problems in that the form of the optically
`within this angular range.
`conductive plate is complicated， the fabrication of this
`Howcvcr，both of thcapovcprior-art tcchniq出 shave design is extremely diffic山， and it is also difficult to make
`problGIns-Thcarst oncSImply placcs a light-scattcrmg55thcdot pattcrn of thclight-scattcring rcncctivclayGr invis-
`refiective plate on the rear surface of the optically conduc- ible.
`timplatcso that thccmittcd light has a comparatmly sharp
`An objcctMofthcprcmtIIIVGIltiOI11s thcrcforcto solvc
`distribution that pcakS at an ang160f60dcgrccs to thcthGabowproblcms WIth thcpr10r art and prOvidca Hat 11dlt
`normal of the surface of the optically conductive plate・ sourcethat implements a uniform and very bright light that
`Th c r c fo rc a p h c n o m c n o n m M m d i n wh id -c d 伊 6 0 f 6 0 is l im i tc d to a p r民ι吋巾州de耐ιd此 伽t民町ι釘叩悶r口rm1
`lumin凹1a叩nc∞ιiおsms凱叩uf血五C1おι引叩n凶1tin t白hι normaldω1r民ιctl旧on(t出hι forward
`\~'~~ ，v， VV<U~ variations in luminance due to position within the light
`di即 tion)where b再 htnessis most required， while optical surfa∞， without i即 reas1昭 thepower consumption， amount
`e?e，r~y is wasted in the lateral directions where it is com- ~;:ll~~t'ge~~-r~t~d~-~rt-h~-~i~~-;f.th~-e~ti;~-~;;~;~t~~
`pletely unnecessary.
`The second prior-art technique has a problem in that， 65
`DISCLOSURE OF THE INVENTION
`The present invention achieves the above objective by
`when a lenticular sheet that comprises an array of a large
`number of individual triangular prismatic lenses is super- providing a fiat light sour∞that uses a light -di旺usingsheet
`
`SONY_000962
`
`

`
`5ラ944ラ405
`
`4
`3
`FIG. 11 is a sectional view showing how some of the light
`formed of a transparent material containing no particles of a
`light-diffusing agent. The front surfa∞of this light-diffusing rays proceeding towards the exterior of the optica11y con-
`sheet has minute irregularities formed at random; these ductive plate are totally refiected while others are
`minute irregularities have a surface roughness of at least the transmitted， when the light-diffusing sheet of the present
`wavelength of the light from the light source， but no more 5 invention is used;
`than 100μm; and， when a cumulative freq~ency distri?utio?
`FIG. 12 shows an example of the method of fabricating
`curve of the heights of the mim出 irreg山rities お ~~ott~d，
`the light-diffusi時 計leetof the present invention;
`with thcpcrccntagcof thcc11II111lativcfrcq116ncy distrib11t10n
`FIG.13is a pcrspcctivcvicw of ancxamp160f thc
`of thct161ghts of thCSC1rrcg1laritics along thcY4X1s and thcligtltEditrusing st166t of thcprcscnt iI1VGIltion，fabricatcd by
`t161ghts of thcmmutcirrcgulantics along thcX-aX1s，thG10thcfabrication mcthod shown in FIG.12，
`cumulative frequency distribution curve has a convex por-
`tion oriGIltcd towards a lowcr sidcof coordinatcs and thcFIG.14is a cross-scctioml V16W through ancdgc-11t Hat
`light source of the prior art， showing the lack of a lens sheet;
`average value of the heights of the minute irregulariti
`FIG.15is a pcrspcctivcV16w of thccdgc-lit Hat 11ght
`grcatcr than a II16dIaIIva1116thcrcof
`A light sour∞ is disposed along at least one s比 edge 15 so可ceof the prior art， showing a lens sheet having a fiat rear
`surface of this light-diffusing sheet， and the light-diffusing surrac芯;
`sheet can be pr~vided sup;rimposed on a light-emitting . _FIG. 16 is a sectional view of the configuration of FIG.
`surface of an -optica11y co-nducUve member that is a fiat 15;
`optica11y transmissive plate， or an optica11y conductive
`FIG. 17 is a graph of cumulative frequency distribution
`I田 I由 erthat has a即 tangularcav町 therein，where the 20 f(R)， with su巾 ceroughness (that is， the pe悶 ntageof
`optica11y conductive member has a light-refiecting layer on cumulative frequency distribution of depths R of concavities
`the rear surface thereof.
`in the mold) plotted along the X-axis and with surface
`The light-di旺usingsheet may also be provided in such a roughness (that is， the d~pths R of the concavities in the
`manner as to cover a window in a lamp ho四 時 .This lamp mold) plotted along the Y-axis， in a fab山 ationmold for
`housing is configured to contain a light source， light- 25 imprinting projections of the light-diffusing sheet in ac∞r-
`refiectiiJg wa11 su~faces of the lamp houiing cover the ~ear dance with the present invention;
`and side surfaces of the light source， and the window is
`FIG. 18 is a sectional view of a fabrication mold having
`formed in the front surface of the light source.
`the characteristic of the cumulative frequency distribution
`When the above desc巾 edopt悶 11yconductive r田 mber curve fA(R) in FIG. 17;
`is formed of a fiat， optica11y transmissive plate， the front 30 FIG. 19 is a is a sectional view of a fabrication mold
`surface of the optica11y conductive member may be a fiat having the characteristic of the cumulative frequency dis-
`surface having a surface roughness less than the wavelength tribution curve fB(R) in FIG. 17;
`of the light of the light source.
`FIG. 20 is a sectional view illustrating undercutting
`A sheet that is a one-dimensional or two-dimensional _ _ formed by aggregations of minute spherical particles of the
`array of convcx or concavclGIlscs may bcsupcr1mposcd35II16tal chroIIIC，dlIrIIlg thcmattc-plating of ct1mmconto thc
`over the light-diffusing sheet. Similarly， another， identical indented surface of the ro11 mold used for fabrication;
`light-diffusing sheet may be superimposed over the first
`FIG. 21 shows a graph relating to the heights of projec-
`light-diffusing sheet・
`tionsof the light-diffusing sheet used in this invention (that
`40 i~.' th.~ su.rfac~ roug?neSS of the _lig.ht-diffusing sh~~t) ~nd ~he
`BRIEF DESCRIPTION OF THE DRAWINGS
`distribution thereof as a cumulative frequency distribution
`FIG. 1 is a perspective view of an example of a trans-
`e f(R)， with surface roughness (that民 thepercentage of
`mlおs錨悶即s釘町i討V刊ι卵 Oぱf付d剛 ayd白伽削ι町叩V札lC∞ιu叫 叩 山 吋 叫dge伊ιト-山押ιωOぱfnaMt c叩uml叫1孔1
`light s回O叩urc∞ιmaωcc∞or吋da叩nc∞芯 witht白hiおsmvι叩nt
`plotted along the X-axis and surface roughness (that is， the
`FIG. 2 is a pe町 民tM?icwof ancxamp160f a trans- hights R ofthcpcaks)along ttICY-aX1s，in a casιin wh副u山ichh 1
`mlお錨悶s釘lV刊ιty押pι of display dιeVl羽lCι us釘m児ga bac牛k-μ-1脳i江tt旬yp戸ιOぱffiat 4将5t白hι cα叩u旧u凹1m旺m凹 凹nu山I
`light s回O叩ur∞maωcc∞or吋da叩n∞witht白hi凶smv刊ι叩n凶h旧on町，
`c∞onvιX町 anda r民ιlationship(average val田主medianvalue)
`FIG. 3 is a cross-sectional illustrative view through an is satisfi~d:
`example of an edge-lit fiat light sou悶 ， showinggroup?of
`FIG.22is a f時 間ntaryexpanded three-d・
`22ttions fO鵬 don both Sl山 esof the light-diffu叫 50 visual凶 onof measurements showi削 叫rojectionsof a
`ligh加t-dω1旺u凶smgs油hιιetusια吋正din t白hiおsmvια叩ntionhaving t白hιcumuト-
`FIG. 4 iおsap肝ι坤 ι午?一ti討Vι V司!ιwofan ι xample ι Oぱfa leι叩n回ss油hι∞ι t lhaM叩tiv刊ιf仕rι叫qu民即mι引叩n町1
`us鈴ιdby t白hιpr民ιs民ι叩n凶t 1 m n V c n t 1 0 n ; F I G . 2 3 s h o w sa graph rclating to thchcights of projcc-
`FIG5is a pcrspcctivcvicw of aIlothcrcxamplcof a lGIIS tions of thclight-diEusing shcct11scd in this inVGIltion (that
`shcctuscd by thcprcscnt1nvcnt10n;55is，thcsUrfaccroughI16ss of thclight-diirusing st166t)and thc
`FIG. 6 is ape町 民tiveview of a fu巾 erexample of a lens diおs叫山山t佐tnゐbu凶凶tiぬont白h悶ιrι∞ofas a cum旺m凹n
`shι∞ιet 山 ιdby t白hιprιsι叩ntmvι叩nhon町，
`curvιf(R)， wi江ths乱1ぱ acιro叩ughnιss(that院 t白hιpιrcι叩ntagιof
`FIG. 7 is a perspective view of yet another example of a cumulative frequency distribution of heights R of the peaks)
`plotted along the X-axis and surface roughness (that is， the
`lens sheet used by the present invention;
`FIG. 8 is a perspective view of an example of two 60 heigl山 Rof the peaks) plotted along the Y-axis， in a case in
`superimposed lens sheets used by the present invention;
`which the cumulative frequency distribution curve has a
`FIG. 9 is a s ι∞ωctiona札1viおιw sl油howir時 t白hι p抑凶aths0ぱf日lightr悶ay戸s downward c∞or肝 ι xity and a r ι lat 則
`t佐ravι11ingfrom t白hιint民ιriorof t白hιoptiたca札11砂yconducti討Vιpμla剖tιvaluιE註~mιdωian value) is satisfied;
`to the outside thereof;
`FIG. 24 is a partial expanded three-dimensional visual-
`FIG. 10 is a sectional view showing light rays that have 65 ization of measurements showing the projections of a light-
`been emitted by the tunnel e庄'ectfrom the optica11y conduc- di旺usingsheet used in this invention having the cumulative
`tive plate as they proceed into the lens sheet;
`frequency distribution characteristics of FIG. 23;
`
`SONY_000963
`
`

`
`5ラ944ラ405
`
`5
`6
`FIG. 25 is a graph showing the heights of projections of source will be described below with referen∞to the aωom-
`the light -di旺usingsheet used in this invention (that is， the panying drawings.
`SUrfaccroughI16ss of thclight-diirusing st166t)and thcdis-An cdgc-lit typcof Hat light sourccis shown in FIG.1.In
`trh11t10IIthcrcof as a C11II111lativcfrcq116IICy distribut10IIthis agurc，rcfcrcnccI111mcra11dGI10tcs an optically
`ιf(R)， with surfacιm
`c叩u旧1m凹nu孔lU叫tla剖叩ti討Vι f仕rι叫q甲uι叩nc可ydistribution of heお悶ιel氾gh加ltsR 0ぱft白hι p ι aks)
`configured of a solid optically transmissive fiat plate. A light
`plotted along the X-axis and surface roughness (that is， the
`source such as a linear light source 3 is provided along one
`heights R of the peakρplotted along the Y-axis， in ‘
`which批 averagev山'/~fiù;a~~~~;a~i~~~.~t52o/~ ;~d-th; edge su巾 ccofthisopticallyconductivcplatc1Ardcctivc
`C11II111lativcfrcq116ncy distribution curvchas a downwardly mirror 5is prOvidcd bchind thc11ght sourcc3.Light cmittcd
`convcx portion and anupwardly convcx portion，
`10from thclight sourC636ntcrs thcmtcr10r of thcoptically
`FIG261s a partialcxpandcd thrcc-diII16IISIonal VIsual-conduct1vcplatc161thcr dircctly or aftcr bcing rcncctcd by
`ization of mcasurcmcnts shOWIng thcprojcctions of a light-thcrcncctivcmirror (also a lamp housing with rcncctivc
`diffusing sheet used in this invetrtion having the cumulative surfa∞s) 5. It is refiected internally as shown for example in
`frequen~y distribution characteristics of FIG. 25;
`FIG. 3 or it is emitted directly outside from within the
`FIG.27is a graph showing thchcights of projcctions of 150ptICally conduct1vcplatc1A light rcncctmg laycr2is
`the light -diffusi時 sheet1脱 din this i町 四tion(that民 the provided on the rear su巾 ceofthe opt悶 llyconductive plate
`su巾 ceroughness of the light-diffusi時 sheet)and the dis- 1. The surface of the optically condl則 iveplate 1 opposite to
`tribution thereof as a cumulative frequency distribution the light refiecting layer 2 forms a light-emitting surface. A
`curve f(R)， with surface roughness (that is， the percentage of light-diffusing sheet 8 is provided facing this light-emitting
`c叩umu叫山la剖t附 f仕rι叫q甲uι叩nc可ydis坑t巾 u凶tionof he凶お削ι1培gh山tsR0ぱft白hι p戸ιaks) 2却口 s乱叩山ur町Irf白ac∞芯， and li培gh加ltι引叩悶I旺m凶I
`plott旬凶ι吋dalong t白hι X-axis and su巾 ce roughness (that 民 the passes through the light-diffusi 時 sheet 8. Light that has
`heights R of the peaks) plotted along the Y-axis， in a case in passed through the light-diffusing sheet 8 passes through a
`which the cumulative frequency distribution curve is linear; lens sheet 4 and then reaches a transmission type display
`FIG. 28 is a partial enlarged perspective view of projec- device 6. Agap 9 is formed between the light-di旺usingsheet
`tions of a light-diffusing sheet formed of ridges of a rect- 25 8 and the optically conductive plate 1， and between the
`angul~r equi~ateral trian_gu1a.r sectional shat:e~~n~d ~~ving the light-diffusiu"g she~t 8 and the lei-Js sheet 4. Projections 41
`th-at will be d~scribed in more detaillater are for~ed on the
`cumulative frequency distribution curve of FIG. 27;
`FIG29is a graph shOWIng thchcights of projcctIons of SUrfa∞s of the light-diffusing sheet 8 facing these gaps 9.
`the light -di旺usingsheet used in this invention (that is， the
`、 ， r1'~~v __ Instead of being solid， the optically conductive plate 1
`surface roughness of the light-diffusing sheet) and the dis- 30
`ld have an empty structure. In such a case， the light-
`tribution thereof as a cumulative frequency distribution
`ιf(R)， with surfacιm
`~白hι s叩u巾 c∞ιt白hお即ιr民mι∞Oぱfin c∞on凶taω削ctγ叫iththeおιlight r民ιefi此ι∞ωctin時glayι釘r
`c叩umu山 t附 fr叫 uι引叩nc可ydi出s坑山如t位凶n巾ibu凶tio叩noぱfhe凶お削ι1培gh凶H山tsR0ぱft白hι p戸ιaks)
`plottcd along thcX-axis and SUrfaccroughncss (that is，thc2would cach bcin thcform ot a Hat platc，with thcspa∞
`heighは ofthe p叫 s)plotted伽 gthe Y-axis， in aωιin 35 伽 ebe附 enforming a rectangu加 cavity
`which the cumulative frequency distribution curve has a -- With a back-lit light source as shown in FIG. 2， the light
`partial upwardly convex portion and a partial downwardly source 3 is a linear or point light source and accommodated
`convex portion， and the average value is less than the within a lamp housing 5. The lamp housing 5 extends over
`median value.
`the rear and sides of the light source 3 and acts as refiective
`FIG301s a partialcxpandcd thrcc-diII16IISIonal VIsual-40SUrfa∞s for refiecting the light from the light sour∞3 in the
`ization of measurements showing the projections of a light- ~V direction of the light-di旺usingsheet 8
`In FIGS. 1 and 2. referen∞ number 100 denotes a fiat
`diffusing sheet used in this invention having the cumulative
`ligl山 O叩u悶 m引山i江ts“ 叩ι引n出lt白i止h同r民削ιt旬yand民 ばfe釦ι釘r民ια叩 叩n即lCι引 叩m凹1U凹m帥I
`frequency distribution cha 印 t民町附ι釘印n出lS坑tic凶s0ぱfFIG. 29玖;
`FIG. 31 iおsa graph showing t白hιhιi氾gh加ltsof pro吋jιctions，of a display dιVlたcιinits ιntirety.
`the light -diffusi時 sheet1脱 din this i町 四tion(that民 the
`surface roughness of the light-di宜USl時 shcct)andthcdIS-45In accordanccwith thおpresenti町 ention，projections 41
`trib11tion thcrcof as a C11m11lativcfrcq116ncy distribution arcobtaincd by formmg miI111tcirrcSIllarIt16s at rand m
`curve f(R)， with surface ro昭 h田 SS(that is，thcpcrccntagcof (such as in a sharkskin pMIG-or a pcar SKIn pattc)
`cumulative frequency distribution of heigl山 R'ofthe p~aks) the e凶 resurface of the light -di宜usingsheet 8. These minute
`plotted along the X-axis and su巾 c∞ι ro叩ughnι ss (that 院 t白h己 i悶 gu叫山la紅叩n出i副tiι伺shavι a surfac ι m
`hお悶ιeight臼sRoぱft白hι p ι aks吟)pμ10ωtt民ιd along t白hι Y-axis， in a case in 50 wavelength of the light emitted from the light source but is
`which the cumulative frequency distribution curve has a no more than 100μm. When the percentages of the cumu-
`downward convexity over the entire region thereof;
`lative frequency distribution of the heights of the minute
`FIG. 32 is a partial expanded three-dimensional visual- irregularities are plotted along the Y-axis and the heights of
`ization of measurements s-howing the projections of a light- these minute irregularities along the X-axis， the cumulative
`diffusing sheet used in this inveu"tion having the cumulaIive 55 frequency distribution curve should typically have a convex
`frequency distribution characteristics of FI(}. 32;
`portion oriented towards the lower side of the coordinates
`FIG33shows thcangular dIStrIb11t10n of luminanccof a and thcavcragcva1116of thct161ght of thcmiI111tGIrrcgu-
`light-emitting surface of a fiat light source (Example 1 and larities should be greater than the median thereof.
`Comparative Example 1); and
`The light-diffusing sheet 8 used by the present invention
`FIG. 34 shows the angular distribution of luminance of a 60 is formed from a transparent material. In this case， the
`tra?Spar~nt. mater~~l ma~ be a (me~h)acrylic ester such as
`light引 出ti時 surfaceof another fiat light source (Example
`8) of this i町 叩t悶 1 .
`polymethyl (meth)acrylate or polyethyl (meth)acrylate
`~
`[where "(meth)acrylate" means either methacrylate or acry-
`BEST MODES FOR CARRYING OUT 1HE
`late throughout the specification] or a copolymer thereof; a
`INVENTION
`65 polyester such as polyethylene terephthalate or polybutylene
`Embodiments of a fiat light source in accordance with the terephthalate; a thermoplastic resin such as a polycarbonate，
`present invention and a display devi∞using this fiat light polystyrene or polymethylpentene resin; an ultraviolet light-
`
`SONY_000964
`
`

`
`5ラ944ラ405
`
`8
`7
`or electron beam-curable， transparent resin which has been angle of diffusion and a uniform luminance distribution
`crosslinked and cured by ultraviolet rays or electron beams; within the surface of the light sour∞， is such that minute
`a transparent glass; or a transparent ceramic material.
`irregularities are formed randomly (such as in a sharkskin
`As ultraviolet light curalヲleresins or electron beam cur- pattern or a pear出 npattern) over the叩 tiresu巾 ceof the
`able resins， comp~itions comprising a prepolymer， oligo- 5 light-~i旺using sheet 8， and these minute irregularities have
`mcr and/or monomcr having，1n1ts II1016C1116，a polymcru-a SUrfaccroughI16ss that is at lcast thcwavclcngth of thc
`ab1611nsat11ratcd bond such as a(mcth)acryloyl group or a light cmittcd from thclight sourccbut is no morcthan 100
`(meth)acryloyloxy group or an epoxy group. In thisμm. When a curve of the cumulative frequency distribution
`of the heights of these minute irregularities is plotted
`conncction，thctcrmqmcth)acryloyl"iS11scd to mcan shown in FIG31with thcpcrccntapof thcc11II111lativc
`九cryloyl"or "methacryloyl" throughout the specification. 10 ;::~~:::~::. .r1~::::;~，::
`frequency distribution of the heights of the minute irregu-
`Such prcpolymcr and o11gOII16r inch1dCan acrylatcsuch as laritics along thcY-axis and thchights of thcscmiI111tc
`urethane (meth)acrylate， polyester (metl中crylate epoxy 町 egularitiesalong the X-axis， the cuml山 tivefreque即 y
`(II16th)acrylatc，and anunsat11ratcd polycstcr.F11rthcr，a distrIb11tion curvcshould tyPIcally havca convcx port10n
`dipentaerythritol penta (meth)acrylate can be exemplified as oriented towards the lower-;ide of the coordinates ;nd the
`15 ~~-;;~~; ~-ai~-~-;f"~h~-h~i~h~-;f-th'~'-~i~-;;t~'i;;~~~î~;iti~~
`the monomer used in this case.
`It is important that these materials contain absolutely no should be greater than the -median thereof.
`With the∞nfiguration as described above， the projections
`light-di旺using particles， unlike in the ordinary light-
`diffusing plate (such as that cited in U.S. Pat. No. 4，729，067) 41 act as a light-diffUsing layer so that light rays .su~h as L1
`For a light-diEusing shcct8for ancdgc-lit Hat light 20and L2incidGIlt on thcrcar SUrfaccof thclight-diEusing
`source， a sheet of the above described transparent material ~V sheet 8， as shown in FIG. 3， are diffused isotropica11y
`that has a thickness on the order of 5 to 200μm is used.
`thereby. Thus the incident light has a uniform angular
`A