SEL EXHIBIT NO. 2038
`
`INNOLUX CORP. v. PATENT OF SEMICONDUCTOR ENERGY
`
`LABORATORY CO., LTD.
`
`lPR2013-00066
`
`

`

`1S.3/R. Komanduri
`
`18:3: Late-News Paper Polarization Independent Liquid Crystal Microdisplays
`
`Ravi K. Komanduri, Chulwoo Oh, and Michael J. Escuti
`Dept of Electrical & Computer Engineering, North Carolina State University, Raleigh, NC 27695
`D. Jason Kekas
`ImagineOptix Corporation, 7202 Doverton Court, Raleigh, NC 27615
`
`Abstract
`fIr driiu,itSiriik' a pu&ti'i:ilioit- iudcpc,uf 'at. dtf/rur'n it',
`liquid
`'nit 'rodisplar on a cc/let 'ii it' 356x256 p/.rc! silicon
`c'rtwu,I
`lU/Ott! distal polai'tanon glaring.'.
`backplam' uSing II('UIUIit'
`Striking runt/is Ott' a/netted lit it stag/c-panel projector it it/u
`tt'IU.'i'(' (Itt' lee/mo/ag)' .curppouts'
`,'e,tto,'ktu/ylt' snap/c o/ntes.
`ti/i TO
`(re/leenanec) of uuiupolui'ced hg/u I.
`c'onri'act
`ilnvngltptti
`7_c?
`00 us total stt 'ut/ia,
`rOt/OS Op/)i'00L /t/ttt! 1000: / and
`rime.
`Introduction
`I.
`(LC)
`to develop a viable I quid crystal
`Our obiecti ye is
`niicrodisp lay inherently capable of modulating unpolarized light
`with strong contrast. Fr the purposeS ol highly efficient projection
`displays. Pri wary appl cation contexts include ultra-portable and
`i tiple went a ii ci d-
`front-project ion sy stems, and we a i ni
`La
`sequel toti-color approach that wall Id he particu I any t'eli suited to
`work with ótend tie-li nti ted light engines (iIIC Itici ing b Lit not h mi ted
`i-Iet'e we specilicaily report on our
`to light-emitting-diodes).
`success in building a 256x256 prototype IL niierodisplay with a
`reflective silicon backplane based on switchable polarization
`gratings [I -4], which arc capable of up to --75% true through pti t
`of ult polarized light, contrast rat is a ppraac Itt no I 000: I
`and
`NOt) jis total switching time.
`
`-1-order
`(-50%fl
`
`1 -order
`(-50%)
`
`(onpolãL' od light .i diffract-0oif-axis)
`
`d---
`
`0
`
`SS -
`
`0-order
`(-100%)
`
`Modulation of tin pot arized light
`tlie unfortunate
`Ii vere nines
`IA' displays on polarizers for high
`dependency of ;tlniost all
`contrast. Most polarizer-free approaches stiffer front poor contrast
`ratio and lithricatiott difficulties [5]. A lhniily of binary LC
`gratings [6-8] and a elnss of holographieaily-formed polntiot
`gratings tPGs) [9-I I] were previously studied for this pttrpose but
`"crc plagued by severe sctttteritig. were I imited to small
`achieve
`hi gil
`di tii'aetio ii
`and did not
`tingles,
`ch l't'raction
`ellicicneies llittiiting contrast and brighniess).
`We first demonstrated expcnnientally transniissive liquid cotstal
`polarization gratings (LUPGs) at 811) 2006 with nearly --100%
`tliflraetion efficiency and lov scattering [1.3]. We have since
`extended this approach to reflective substrates, and achieved good
`holograms ott both aluniinrtnl (Al) minors and pixilated silicon
`(Si) backplanes. The advantages of the reflective mode (over
`transm issive node) are tmtny: half the required IA' layer thickness
`enables laster switehitig speed [4]. smaller grating periods, and
`larger diffiaction angles.
`Becatise of the above-mentioned advantages. we implemented a
`projection system using :t sitigle LUPO microdisplay'atid lick!-
`sequential-color. as illustrated in Fig. Ic. In this conligttration,
`difl'ractittg pixels ('t'/o voltage) send light atround the fold-mirror
`tvhi Ic no n-d i Iliac tin g pixels I w/ hig It
`'o Itage)
`0 [lie SC 'cell -
`Bright Pixel
`Dark Pixel
`
`Screen
`
`(0)
`
`tight engine
`
`ci
`
`projection
`lens
`
`fold-mirror
`
`lens
`
`LCPG
`Microdlsplay
`
`lIt lllllllll:
`cv
`(diffracting)
`
`V>>Vth
`(non-diffractlnq)
`
`.1
`
`I
`
`I
`
`(unpolarized liTht i' ot diffracted)
`.1, 'r IV
`,
`
`PJumlnuni mirror pixel on silicon
`absorber
`Figure t - The potitrization-irtdependent LCPG ttiierottisplay: (a) Sub-pixel contiguration (DV) of the nernatie LC established by
`rite plioto-aliguimettt layers, where only lust-order cl iffraction occurs: (b) High voLtage configuratioti, where out-of-plttne ttligtttnent
`effectively erases the grating and ligltt is reflected specularly: (e) Telecencric reflective projector system; (d) l'ltoto of niierodisplay.
`
`236 - SID 08 DIGEST
`
`/SSN/008-0966X/Q8/3901-0236-S1.00 © 2008 SID
`
`EXHIBIT
`
`r/-G-)s
`
`7_
`
`ITO
`electrode
`
`photo-
`alignment
`\
`layers
`
`I
`1
`
`t
`I LI
`t
`t nematic LC
`
`.1.
`
`I
`
`\c± Y
`
`

`

`\
`
`Table I - A Itigli-level etlinparison of eflielent projector designs for LCl'G microdisplays (assttinptions tleserihetl in text).
`projectton lens
`
`Desiqn
`
`C'
`
`projection lens
`
`-,
`
`projection lens
`')
`C-
`
`18.3/R. Komanduri
`
`projection lens
`
`C'
`
`-
`
`\7f._aerture
`stop
`
`Transmissive
`i---.-.--i LCPG
`Microdisplay
`
`£.
`
`aperture
`.,r(" stop
`
`,,--,
`
`\
`
`1Transmissive
`l-'---''I LCPG
`¶ M'crodisplay
`Sb.
`
`mirror
`
`light
`engine
`
`*fold
`
`aperture
`stop '
`
`-
`
`hght
`engine
`
`ti,,
`
`Reflective
`LCPG Microdisplay
`
`Reflective
`LCPG Microdisplay
`
`CateQO \
`
`N
`
`Mode
`ConFiguration
`Raw Contrast Ratio
`Projection Lens FlU
`Pixci Voltaqe Range
`Pixel Fill-Factor
`Switching Time
`Optimum Application
`
`Telecentric, Dark-Field
`l-liqh ( 1000:1)
`Low (
`1)
`Modest ( ISV)
`
`Reflective
`Non-Telecentric, Bdqht-Field
`Low (- 100:1)
`Standard (-2)
`Low (% 10V)
`
`-
`
`Transmissive
`Telecentric, Bhqht-Field
`Telecentric. Dark-Field
`High ( 1000:1)
`Modest (- 200:1)
`Low ( 1)
`Standard (-2)
`Hiqh (>30V)
`IOV)
`Low (
`
`93%)
`High (-
`Faster -
`600 ps)
`Fronl-Projeclars
`
`Modest
`(- 60%)
`I ntis)
`Fast (C
`Compact and Embedded
`
`Projectors
`
`J
`
`tight directly tack 1110 the light source or ioward ta
`reflect
`aperture stop.
`in icrod splay teell no logy (in
`is in portant to note that L C P( I
`It
`general) presents multiple configuration choices at tile praiccior
`level, includine: reflective Or transtilissive. telecentric or 11011-
`In Table I. we
`elecentric. and bright-field or dark4ield [2].
`illustrate and compare the configuration studied here (see rilsu Fig.
`1(e)). along with lhree addi i ona I opt tons in a best-case see no rio
`(with first-order diffraction angle of ±24' and our cttnentiv-
`order-of-m agn I title
`known
`Reaching
`an
`in ateri a I) -
`11 r
`comparison, we estimate the trends of' several key parameters, and
`assume that the ill u ni in at ion is onpo I arized I from L El )s), operated
`with Cci d-sequent in I-co I or. and has a ± I 2 - divergence angIe at the
`niicrodisplay (rotigltly (kS' diagonal).
`the pri on ty is Ii igh contrast and a a rge r project ion lens
`reflective
`front-projectors.
`then
`the
`in
`acceptable,
`as
`telecentric/dark-tield option is hkeIy best. I fthe priority isa small
`package size and contrast requirements are relaxed, as in ultra'
`transmissive!
`the
`projectors.
`then
`embedded
`poilahie
`teleeentric/bright-fteld option is likely best. \Vhile we employ
`reflective LCI'Gs in this vork. many of tile basic results would
`ztrise similarly in the transniissive-mode.
`Reflective LCPG Properties
`2.
`LU PG s comprise an in-plane. ttn i axial hire fringenc e I'.
`I I I t hrtt
`varies with position (i.e. nfv) - [sin( zrA I. eos(zv/A). 0]. as
`shown in Fig. I). The most compelling features ineltide - 100%
`diffrrtction into the ftrst'orders regardless of polarization, and the
`presence of only the zero- and first-orders (tile conventional
`grating cqttation applies). Usiilg tile Extended Jones Matrix
`method [12]. we derive tile ideal first-order diffraction etTicieney
`in the reflective-mode i Ilunlinated by unpolarized light as
`,f'2rnX,nl
`C'
`
`1/
`
`=
`
`StIt
`
`cosU3
`
`II)
`
`(= (I/I6)cos14 i- 3sinUXS_coslY@ 3sin(/)
`50%. akin
`For small alleles of iticidence (C 201, C - I and t/tI
`is tue vacuunl wavelength.
`to transmissive operation II] Note,
`At, is lIe hirefringence. d is the gratitig tilickness (Fig. I). atid 11
`
`2)
`
`is the incident angle of light within the LU. Nettrly all incident
`I ight is di ITracted into the first-orders it the q uarteflvttve condi ti0,1
`retcardiess of i tie i tie it polarization. Note that an
`= ) /(4 \n ) .
`applied voltage above the thi-eshold Fth t typ. -2 V) reduces An,
`redirecting incident I gut in to I he zero-order. 13 oth I he ft rst- and
`zero-orders can therel'ore be modulated between -0% to -IOU
`lie tktit atIg les and 2.
`fr uopuhir,:crJ light 0 verara OSC of
`Reflective LCPG Fabrication
`3.
`Prior work oIl LC'PCis has been solely Iècused (to our knowledge)
`on Iransnitssi ye stthstrtttes Ii - 9. ID]. 1-lere ve report attr sttccess
`in prodticing excellent quality LCPGs on Al tllirrors and good
`quit h tv gritt i ngs 0(1 reP ecti ye Si backplanes. Reflective iabri cation
`is fitr mote di Ui ett it than on Ira istii issi ye stthstra tes because the
`re lice t i on of the holographic record itt g bert Ins corrupts the
`interkrence througllottt the recording vol unle (e.g. tile intensity
`within the polarization hologram no loiiger remains constant).
`therefoni. our approach involves removing the re Ilection of the
`C lJV) itcording beatils from the suhstrate using a UV
`ultraviolet
`absorhitle layer, while otltcrwise following standard lhhrieation
`procedure 11.9].
`I ) [he reflective
`u'abt'ieat i on in vol yes the following basic steps:
`suhstrttte and iTO-glass (Delta l'ectltlologies) atre cleaned with
`met Ilati ol: I 2) The reflect i "e substrate is spiti -coated with it t IV
`(i.e. 9:1 wt/vt mix of Wide-i SB (Brewer
`absorbing nlalerial
`Sc i dIce) and 2-2'-d i hv droxbenzoplie tulle (S igmrt-A Idri ch)) at
`6000 rpm for 60 s. followed by a post-bake on a Itoipiate at
`II 0°c:: 13) Both sitbsirates arc coated with a photo-alignnlenl
`I 3j ROl'- I 03-2CP ( Rolic). at 3000 rpnl
`ft,r 45 s.
`material
`followed by the standard post-hake: (4) Stthslrates are tailed
`togdt her, where the cell gitp is ii a inrai ned with I . I
`tn xiii c:t
`(Dana Enterprises) dispersed withitl
`tile glue seal
`spacers
`(Norland): (5) The assembly is then exposed to a UV ptllariztltioll
`hologram Ironi a I icC 'd laser (325 tt m).
`it h ortll ogotia I ci ct' I an y
`0.5 i/cia') at grating period A - 2.6 pm
`poirtrized beams ((lose
`(i.e. 140 diflinction angle at X-- 632 iitti): (6) Finrtliv. the nematie
`0.14$. Tvr I0O°Cl was
`liquid crystal MDA-06-177 (Merck. A;'
`I 20°C for 5 nh II. The
`filled at rootn temperature. and an nettled at
`re liective substrate consisted of either an Al mirror (Edmund
`
`(
`
`SID 08 DIGEST - 237
`
`

`

`100
`
`80
`
`>.
`
`a,
`C)
`
`t60
`
`C)
`
`40
`
`I-
`a,
`
`-20
`
`920
`
`0 U
`
`.
`
`0 1
`
`0.8
`
`to
`
`E0a
`
`)EPa
`
`)C
`
`-C.
`
`C)
`
`2
`
`4
`6
`Voltage (Vrms)
`
`8
`
`10
`
`0)
`
`0.2
`
`1000
`
`800
`
`: 600
`
`Cu
`
`400
`C0o 200
`
`05
`
`-
`
`20
`
`15
`10
`Voltage (Vrms)
`Figure 2 - Electi'o-optic beltavior of Reflective LCI'Gs
`forntecl on Al mirrors: Voltage response (a) of grating
`efficiency and reflectance (inset); (b) Sub-ms witching times:
`and (e) Contrast ratio of the first-order diffraction of a HoNe
`laser (633 nm). (For parts (a) & (b), A 2.5 ;un and d
`1.4
`grn, and in part (c). A = 4.0 jtm and d= 1.6 ;tnt)
`
`18.3/R. Komanduri
`
`Lnt pixel
`a 256x256 pixel Si backplane (24
`Optics), or
`wtdthlheight. Boulder Nonlinear Systems). In all eases, excellent
`quality gratings were farmed with low scattering (.L 1%)-
`
`,,
`
`Results
`4.
`We will first consider results front LC'l'Gs lbrtned on Al mirrors,
`wherein we expect our best results since the reflective substrate is
`tin' foim (i.e. no topography or structure to influence the hologram
`fonnation or degrade diffractive behavior). Several definitions
`will be helpftil as we characterize the inherent properties of
`/ +/,4-/, +...),isa
`LCPGs:(i)gralingtjJfrieflcy ,,_'.-
`normalized term that describes the inherent di fiction behavior of
`the LCPG layer alone, and is directly comparable to Eq. (I ); (ii)
`(I + L) " 1ts is a true (un-
`list-order re/kttonce R
`intal
`normalized) measure including all substrate. interface, and grating
`effects: and (iii) full-on-lull-off -mtIrust ,-at,o. defined as
`/
`is the metLsured intensity of the 111ih
`In each of these,
`4 .'..
`is the incident intensity, and /05.01:1:
`reflected diffraction order, 1
`firs i-order incident
`ititensi ty.
`the max i niunVnii n i at a to total
`is
`Eleetro-optie nicasurernents on mirror-stibstrates involved a 4 kl4z
`square wave (with zero DC bias), while those far the niierodisplay
`employed a 120 Il-, sub-flame (field) rate.
`Reflective LCPGs On Mirrors
`4.1
`The voltage response of a reflective LCPG (M2,5tm. d I .4pml
`farmed on att Al mirror is shown in Fig. 2a. The grating efficiency
`and reflectance (of the first-orders) was measured with a IleNe laser
`(633 am) and with tinpolarized LEDs (collimated for
`this
`nicasurement to about a4°). Ve obsee that the LCPG diffracted
`appreciably near the 100% theoretical
`the laser with Eli,
`value. Perhaps tnore prominently, the red LED produced a high
`peak eflieiency Eq,185% and reflectance R=75% at 2AV (with
`slightly lower values for green and blue LliDs). These losses are
`predominantly due to air-glass interface and electrode-absorption
`losses. Crucially, this reflectance is sigailicantly higher than any
`(e.g. VAN-mode) thai
`employs
`rellective LC tnierodisplay
`polarizers. As expected, the applied voltage redtteed the diffraction.
`
`The dynamic response was also measured, where a sub-ms total
`switching times are typical 141. clearly enabling field-sequential-
`color operation. Fig. 2b shows the rise and fall times ( 10%-c0%
`transitions) of the LCPC switching from OV to the indteated
`applied voltage. While the overall speed (< 800 jsF) of this
`ncnmtic i_c: configuration is comparably fast, the general trend is
`similar to other LC modes: rise-time is strongly dependent on
`voltage, while hI I-time is roughly constant.
`As can be deduced from Fig 2a, the dark state results from a high
`voltage (i.e. a drive-to-hlack configuration), and is crucially
`dependent on the interactioti between the applied voltage and the
`surface anchoring strength- The contrast measured on two of our
`best samples (M4.Optn. &I.6gni. IvILC-12100-tJOO) is shown in
`Fig. 2c. along 'vith the typical range values. We observed that for
`at least sonic of our samples, contrasts approaching 1000:1 are
`possible at modest operating voltages of 22 V. Note that we are
`currently focusing our materials optimization effot-t on lugher
`contrast at lower voltages with small grating periods (S2.SFm).
`
`Reflective LCPG Microdisplay
`4.2
`The voltage response ol' a relleetive LCPG (A=2.61tm, d= I .4fun)
`Farmed on a 256s256 pixel Si backplane is shown in Fig. 3. The
`grating eficieney behavior is substantially similar to Fig. 2
`(<80%), with maxima that at-c only slightly lower, implying that a
`
`238
`
`SID 08 DIGEST
`
`

`

`18.3/R. Komanduri
`
`aperture stqp!turn-rntrror
`
`(a)
`
`LCPG
`mlcrodl
`
`Ia
`
`eclion lens
`
`(b)
`
`In
`
`LED tIght englpe
`(Goldeneye)
`
`Figore 4 - l'nlarizer-free projector prototype based on
`LCI'Cs: (a) Photo of tire simple projector system, with three
`lenses, a fold-mirror. LEDs. and projection lens: and (b) A
`projected image (from 9cc Age 2" movie. 20th Century Fox).
`
`Acknowledgements
`6.
`The authors gratefully acknowledge the stipport of the National
`Science Fotindatioti (ECC:S-062 1906) and the Kenan lnstittttc for
`Engineering. Technology, and Science. We ttlso thank Bottlder
`Non! inear Systems Inc- a id Go Idcneyc lire. lbr deep technical
`support in integrating LC:PG technology with the LCoS backplane
`and fr providing the I gut-recycling LEl) source, respectively.
`References
`6.
`[I] M. J. Esetuti, V. NI. Jones, S/I) .t-nq L)ige.vt. vol.37. pp.
`1443-1446 (2006).
`
`[2] W. M. ,loncs, 13. C.. Conover. NI. J. Escuti .5/fl S:tvop. Digest.
`vol. 37. pp. 1015-1018 (2006).
`
`13] R. Koinanduri a al., J. Soc. jul DLcpL. vol. IS. PP 589-594
`(2007).
`
`[41 It. Kotnariduri, NI. J, Esetiti. Phi's. Ret. 5. vol. 76. p'
`021701 17007).
`[5] D.-K. Yang. .1. Soc. fat DispL. vol. 16, pp. 117-124(2008).
`[6J J. Chico " al.. .-lppI. I'/n:c. Len., vol. 67, pp. 2588-2590
`(1995).
`[7] C. M. l'itus, P. J. f3os. .4p1;L P/mt tat. vol. 7!. pp. 2239-
`2241 (109Th
`
`[81 NI. Honni:t. T. Nose ..,tgt!. Ojn..vol. 43. pp. 5193-5 197
`(2004).
`[9] J. l.akin ('fat. .lppL P/its. Let!., vol. 85. pp. 1671-1673
`(2004).
`ID] II. Sarkissian si at. Opt /.s'(t, vol. 31. pp. 224K-2250 (20061.
`[ll]1.. Nikolova. 1. Todorov. Opt/cu Ada, vol. 3). pp. 579-588
`(1984).
`
`P. \'eh. C, Cia, Optics of Liquid CstaI Displays (John
`Wiley & Sons. Inc., New York. 1999).
`
`NI. Sehadt, II. Seiherle, A. Schuster, Nature. vol. 381, pp.
`212-215 (1996).
`
`5/0 08 DIGEST
`
`239
`
`IOU
`
`j80
`
`60
`
`40
`
`0(
`
`V
`
`b
`
`0
`
`11
`
`13
`
`9
`7
`5
`Voltage (Vrms)
`Figure 3 - Electro-optic Ijetravior of LCPG rnicrodisplav
`(25t5x256): Voltage response of the efflcienc- and reflectance.
`(A2f (tnt and d 1.4gm)
`good quality gTating "as also created on the pixilated backplane.
`We note, however, that the peak reflectance in this case overall is
`lower (-50%). which 'ye attribute to several elTects: a lower
`overall reflectance of the pixel niirror, the loss associated wtth the
`pixel fill-factor, and any di ifiactive eottpl i ng between the pixel'
`array and the LC PC itself. WIt lIe we do not lii I lv
`ride rsta rid it is
`currently, we con tin tie to i west gate this.
`is i in porta it to note
`Ii
`that the switching times are essentially identical to Fig. 2b.
`Prototype Projector
`4.3
`Since the LCN) nierodisplay reflects the zero- :utd first-ut-dot
`with -14° separation. we can i niplernent a polartzer-lrce projector
`Ic and Table I) as a proolofprineiplc. We etnplov (Fig. 4a)
`an LED light source (--90 ni at -8.3 W. Goldeneve Inc.) with
`simple optics and usc field-seqtretrtial-eolor. Note the extrctnc
`sittiplicity of the optical 'guts' of the projector. with only a l'cw
`lenses and a fold-mirror (serving also as the aperture stop). An
`actual image is also shown in Fig. 4h. This admittedly sub-optimal
`projector platfonn nevertheless supports video (120 Hz held-rate).
`rn to the
`presents good color saturation (by eye), sends '-
`5
`screen, manifests 50:1 contrast lbr lhc red LED (within the l3'
`capability), and has an overall efficacy of -1.8 ltn/W. It is clear
`that most of the losses' -n(l the poor contrast arc due to utisttitahlc
`lens choices and alignment, arid we actively continue to i liprove
`ott this toward a goal of> $ lrn/W and much higher contrast.
`
`Conclusiott
`5.
`We have developed a polarization-independent, difl'ractivc. LC
`nsicrodisplay on a reflective silicon backplanc, and implemented a
`prototype projection system with an LED light source using field-
`sequential-color. The approach combines the low cost of a single
`LCoS panel and the high efficiency of DLPrI. and the technology
`enables tiltra-portable. low-power. cotnpact project ion displays.
`While several conipcttng Pocket Projector" approaches are
`emerging. our nsicrodisplay technology represents a dramatic
`potential advantage with respect tL) cost. simplicity, arid power
`savings. Fortherniore, because the technology is scalable in
`resolution, front-projectors are also an attractive application.
`
`