LCOS液晶材料介绍

A Planar Defect
The “bistability” of the SSFLC LCOS cells comes from pinning of the director at the planar defect (the chevron layer interface).
Clark, N. A.; Rieker, T. P. "The Smectic C "Chevron", A Planar Liquid Crystal Defect: Implications for the Surface Stabilized Ferroelectric Liquid Crystal (SSFLC) Geometry," Phys. Rev. A 1988, 37, 1053-1056.
The Chevron Layer Structure
Zig-zag walls in an SSFLC cell
SmA
SmC
Rieker, T. P.; Clark, N. A.; Smith, G. S.; Parmar, D. S.; Sirota, E. B.; Safinya, C. R. ""Chevron" local layer structure in surface-stabilized ferroelectric smectic-C cells," Phys. Rev. Lett. 1987, 59, (23), 2658-61.
Transmitted Intensity (%)
100
0 -10 0
E (V/µm)
10
V-shaped Switching in the Fukuda SmX Phase

Analog EO can be extremely valuable Dream come true: a drop-in replacement for analog NLC EO, but with FLC switching speed Several companies bet that Vshaped switching was the realization of this dream Chemists could never get the SmX phase to behave if the FLC has low P?!?
Curved Polarizing Beam Splitter (3M)
FLCOS (Displaytech)
8 Millionth shipped (Feb, 2005)
DisFra Baidu biblioteklaytech/Samsung FLCOS HDTV
One 0.78” Displaytech FLCOS Chip for each color channel
Robert Meyer - 1974 The SmC* has C2 symmetry, and has a macroscopic dipole moment. z n
Polar Axis (C2)
Chiral Molecules Tilt Plane ≡ Normal to C2 Polar Plane ≡ Contains C2 and z
N C8H17 O N C F2
C F2
O
3M
CF3 F C 4F9Cn H2n+1O O F O O O
Displaytech
O O O
O NO2
V-shaped; Giant Electroclinic; TGB
W415
Bookshelf EO is optically bistable!
If you switch the surfaces, bookshelf devices can be optically bistable. This solves the HDTV problem!
C2
Mixture of C1 and C2 Cause Zig-Zag Walls High pretilt in C2 pulls the director off the cone C1 pulls the director off the rubbing direction
Coneheads?
Speed boats should not be confused with boat wakes!
Rare FLC Varieties
O O O C10 H21 O O
Fujitzu
O F2 C C 4F9
Bookshelf (Mochizuki effect) Bookshelf; AFLC, V-shaped AFLC, Clock phases; TGB; V-shaped
Boulder SoundTrack brochure, Fall 2000
Failed due to manufacturing problems
Sony VAN-LCOS HDTV - 2005
ColorLink Filter
SXRD = LCOS
50” Rear-Projection 1080 p (!) HDTV @ ~ $3,500K Vertically-Aligned Nematic LCOS Volume shipping in time for Christmas, 2005
Brief History of FLCs

1975 - Ferroelectric LCs (Meyer, Liebert, Stryzlecki, Keller) 1980 - Discovery of SSFLC Device concept (Clark, Lagerwall)
– Submicrosecond, bistable LC electro optic effects – APL 36, 899 (1980), U.S. 4,367,924 - most cited TLC paper & patent ever
ANA
n
z
2 µm
P
E
P > 0 (right-handed)
E
Enantiomeric EO Response
z n P n z
P > 0 (right-handed)
P
E
POL
E
ANA z n
P = ƒ(ee)
n
z
P
P < 0 (left-handed)
E
P
E
“Single Molecule in a Binding Site” Model for P
Molecules with polar symmetry can exhibit a dipole moment. C∞v or lower ^ z ^ n The SmC phase has a two fold symmetry axis perpendicular to the tilt plane, and a mirror plane parallel to the tilt plane giving C2h symmetry, which is nonpolar.
z n
Coneheads
n heads Chevron layer interface
Chevron Cells are Not “Optically Bistable”
The C2T cells are bistable, but the field on and field off, states are different
z
n C2h
The projection of the director n on the layer interface below it has nematic order. This polar vector is termed the c-director.
c
The SmC Phase is Nonpolar
Abrikosov phases antiferroelectric LCs photonic applications display applications
1997-2006: The chiral banana phases
– Spontaneous reflection symmetry breaking: Pasteur’s experiment in a
Unichiral Electro-optics can be Useful
“Display Product of the Year Gold Award: Minolta’s DiMAGE 7 Digital Still Camera In its 5-Mpixel DiMAGE 7, Minolta Corp. has pioneered the use of a liquid-crystalon-silicon (LCoS) microdisplay…”
C1 and C2 Chevrons
Director “floats” in the rubbing direction
SmA
C1
To avoid zig-zags, you have to either favor C1 (suppress the C1C2 transition), or favor C2. C1 is favored by high pretilt, C2 is favored by low pretilt and strong azimuthal anchoring.
C1 - C2 transition
Kanbe, J.; Inoue, H.; Mizutome, A.; Hanyuu, Y.; Katagiri, K.; Yoshihara, S. "High resolution, large area FLC display with high graphic performance," Ferroelectrics 1991, 114, 3-26.
C-phase “binding site”
Pcalc (nC/cm2)
Pexp (nC/cm2)
P=
ΣP * D
i
O
i
O
O
F
i conformations
Pi = µi 〈cos α〉
P > 0 ⇒ (R) configuration
FLC on Silicon (FLCOS) Microdisplays
fluid - the first chiral LC phases from achiral molecules » Science 278, 1927 (1997) - Most cited TLC paper since 1997
Basic Geometry of the SmC
Layer Plane ≡ Normal to electron density modulation (X-ray) Tilt Plane ≡ Normal to C2
Speed Boats
The free energy barrier to breaking the pinning at the chevron interface causes domain wall-mediated switching between the bistable C2T states
» Clark and Lagerwall APL cited 1,517 times as of Feb 2006
1980 2500 smectic materials 30 FLC materials 1 FLC patent

2002 30,000 smectic materials 12,000 FLC materials 3,000 FLC patents
Trans-2-butene is a simple molecule with C2h symmetry
SmC
Ferroelectric LCs
Bob Meyer
Noel Clark
Sven Torbjörn Lagwerwall
Reflection Symmetry Breaking in the SmC
Between Glass Plates the SmC* is Ferroelectric
# "= P$ E
The SSFLC Light Valve
The half wave thickness is ~ 2 µm!
Unichiral SSFLC Electro-optics
z
n P
POL