We demonstrate a fast-response liquid crystal display (LCD) with an ultra-low-viscosity nematic LC mixture. The measured average motion picture response time is only 6.88 ms, which is comparable to 6.66 ms for an OLED at a 120 Hz frame rate. If we slightly increase the TFT frame rate and/or reduce the backlight duty ratio, image blurs can be further suppressed to unnoticeable level. Potential applications of such an image-blur-free LCD for virtual reality, gaming monitors, and TVs are foreseeable.
High resolution displays using ferroelectric liquid crystals (FLCs) driven by a single crystal silicon backplane are a powerful option for many current and future applications. The FLC light-modulating layer is placed on top of a reflective CMOS backplane. This geometry effectively takes advantage of the fast switching speed and high resolution possible in a sub-micron thick layer of FLC and fine design rules available in standard CMOS fabs. The microsecond FLC switching speeds allow both gray scale and color to be generated with time sequential addressing. In addition, low temperature performance is remarkable ad showing switching in the sub-50 millisecond regime down to -40 degrees C. Current FLC materials operate well with mainstream 5 volt CMOS as well as with newer 3.3V processes. These lower voltages result in lower power consumption and finer design rules allowing for higher density of on-chip electronics such as MPEG2. This option is difficult to achieve in higher voltage processes typical of nematic on VLSI devices. The reflective quarter wave plate design of the display affords a large angular acceptance resulting in flexibility of optical design as well as excellent contrast and throughput vs. viewing angle. We will describe 24 bit color displays and the FLC mixtures optimized for their particular application.
KEYWORDS: LCDs, Reflectivity, Switching, Birefringence, Temperature metrology, Projection systems, Hand-held displays, Very large scale integration, Fast packet switching, Standards development
We describe hand-held magnified view and single panel color projection displays based on active matrix ferroelectric liquid crystal (FLC) technology. The FLC light-modulating layer is placed on top of a reflective CMOS backplane. This geometry effectively takes advantage of the fast switching speed and high resolution possible in a sub-micron thick layer of FLC and fine design rules available in standard CMOS fabs. The fast FLC switching speed allows both gray scale and color to be generated with time sequential addressing. Current FLC materials are well suited to operation with mainstream 5 volt CMOS processes and offer a clear path to compatibility with newer 3.3 and 2.5 V processes. These lower voltages result in lower power consumption and finer design rules allowing for higher density of on-chip electronics such as MPEG2. This option is difficult to achieve in higher voltage processes typical of nematic on VLSI devices. The reflective quarter wave plate design of the display affords a large angular acceptance resulting in flexibility of optical design as well as excellent contrast and throughput vs. viewing angle.
we demonstrate that with a single manufacturing process and custom FLC materials, individual reflective FLC SLMs can be optimized for a wide range of chosen wavelength regions. One lot of 256 X 256 SLM cells were prepared from a single silicon wafer. These cells were filed wit five different FLC materials having birefringence spanning a range from 0.129 to 0.218. The resulting retardance variation allowed SLM characteristics to be tailored to give optimized performance in any wavelength region from 400nm to 1000nm.
KEYWORDS: Photonic integrated circuits, Reflectivity, LCDs, Projection systems, Switching, Temperature metrology, Fast packet switching, Standards development, Birefringence, RGB color model
We describe a single panel SXGA projection display based on active matrix ferroelectric liquid crystal (FLC) technology. The FLC light-modulating layer is placed on top of a reflective CMOS backplane. This geometry effectively takes advantage of the fast switching sped and high resolution possible in a submicron thick layer of FLC and fine design rules available in standard CMOS fabs. The fast FLC switching speed allows both gray scale and color to be generated with time sequential addressing. Current FLC materials are well suited to operation with mainstream 5 volt CMOS processes and offer a clear path to compatibility with newer 3.3 and 2.5 V processes. These lower voltages result in lower power consumption and finer design rules allowing for higher density of on-chip electronics such as MPEG2. The reflective quarter wave plate design of the display affords a large angular acceptance resulting in flexibility of optical design as well as excellent contrast and throughput vs. viewing angle. We describe this color projection display and the high temperature FLC materials and mixtures optimized for them.
FLCs exhibit the electrooptic speed necessary for construction of full color, high resolution FRAM-based microdisplays. Special FLC materials are required to meet the performance characteristics required of these reflective microdisplays. The specifications for FLC mixtures for several applications, an approach to formulating them, and several key dopants used to attain the mixture specifications are presented herein.
FLCs exhibit the electro-optic speed necessary for construction of full color, high resolution DRAM-based microdisplays. Special FLC materials are required to meet the performance characteristics required of these reflective microdisplays. The specifications for FLC mixtures for several applications, and an approach to formulating them, is presented herein.
Ferroelectric smectic C* liquid crystals have been shown to exhibit high speed, electro-optic switching when incorporated into the surface stabilized ferroelectric liquid crystal (SSFLC) light valve. Certain applications utilizing IR modulation, waveguide, and phase modulation, and certain fiber-optic devices, can benefit from materials with a birefringence higher than that typically seen in FLC materials ((Delta) n approximately equals 0.15). A new class of compounds, the tolane cinnamates, was developed to help meet this need. These compounds combine a cinnamate moiety with the well known high birefringence tolane core, resulting in two improvements: first, the birefringence increases from 0.24 to 0.29; and second, the tolane cinnamate system is significantly more stable to UV light than the parent tolane system. The new materials show smectic C as well as nematic phases and demonstrate good compatibility with both nematic and FLC hosts.
Ferroelectric smectic C* liquid crystals (FLCs) have been shown to exhibit high speed electrooptic response when incorporated into the surface stabilized ferroelectric liquid crystal light valve. An important component of the FLC material used in devices is the smectic C host, which imparts many of the important characteristics to the final mixture, allowing customization to a specific type of device. A new class of FLC materials based on a cyclohexenyl core is reported and their properties evaluated in both the pure material and mixtures.
We report here on analog modulation effects in ferroelectric liquid crystal (FLC) materials and electrical drive schemes that are appropriate to FLC/VLSI spatial light modulations (SLMs). The deformable-helix ferroelectric (DHF) effect paired with fixed-charge drive can give sub- millisecond grey-scale response with VLSI-compatible drive voltages. New DHF materials with long-pitch nematic phases give superior alignment quality and contrast ratio. We present analog FLC driver circuits suitable for VLSI implementation, and show that providing adequate read/write isolation in optically addressed FLC/VLSI SLMs requires special care.
We have recently described initial results of a project directed towards the design and synthesis of low molecular weight ferroelectric liquid crystals (FLCs) for second order nonlinear optics (NLO) applications. FLCs with useful magnitude of the second order susceptibility (chi) (2) and processibility not possible with poled polymers or crystals have been obtained. However, for some applications liquids are not appropriate. For these applications we have been exploring the use of FLC polymers (FLCPs), and more specifically FLCP glasses. IN our view FLCP glasses represent a novel type of solid, a truly noncrystalline solid with thermodynamically stable polar order. High molecular weight FLCPs, however, suffer from very high viscosity in the isotropic state, precluding some attractive processing approaches such as capillary filling. Building upon the pioneering work of the Wacker LC-silicones group, we herein report on the synthesis and some properties of members of a class of cyclic oligosiloxane FLCs combining some of the advantages of both low molecular weight FLCs and FLCPs.
Ferroelectric smectic C* liquid crystals have been shown to exhibit high speed, multistate electro-optic switching, particularly when incorporated into the surface stabilized ferroelectric liquid crystal (SSFLC) light valve. Certain applications utilizing IR modulation, waveguide, phase modulation, and fiber-optic devices can benefit from a birefringence higher than the value of (Delta) n equals 0.15 seen in typical FLC materials. By incorporating the highly conjugated diacetylene moiety into an FLC core, an increase in birefringence greater than (Delta) n equals 0.3 is achieved. Lateral fluorination of the core induces a strong preference for the tilted smectic C phase as compared to the unfluorinated materials which typically show the nematic phase. The effect of other substitutions is explored on the mesogenic properties of the basic core structure.
We prepared ferroelectric liquid crystals (FLCs) possessing a newly designed chiral part, 2- fluoro-2-methylalkanoyloxy group. The new chiral moiety was derived from the corresponding chiral epoxides biologically produced. Physical properties of the FLCs with the new chiral moiety were compared to those having another fluorinated chiral moieties. The 2-fluoro-2- methylalkanoyloxy group greatly contributes to producing a large spontaneous polarization (Ps). Effects of core structures in the FLC molecules were also investigated. A prymidine ring in the core part extremely enhances the Ps value. In order to prepare a practical FLC mixture, the novel chiral compound with the large Ps was doped in a base mixture having a wide temperature range of smectic C phase. The mixture exhibits a fast optoelectrical switching time and an appropriate tilt angle. Its performance in a multiplexing device was also investigated.
Ferroelectric smectic C* liquid crystals have been shown to exhibit high speed, multistate electro-optic and display device applications, particularly when incorporated into the surface stabilized ferroelectric liquid crystal (SSFLC) light valve. The SSFLC geometry results in two distinct stable states. Unfortunately, the lack of intermediate electrically addressed states precludes a natural gray-scale effect. The recently discovered Deformed Helix Ferroelectric liquid crystal (DHFLC) effect opens the door to linear gray scale or linear phase modulation in a ferroelectric liquid crystal device on a microsecond time-scale. One drawback of currently available DHFLC materials is that their alignment quality is limited due to the lack of a nematic phase above their smectic A phase. While alignment can be improved by the use of shear techniques, this represents an undesirable option for a manufacturing process. We show that DHFLC mixtures can possess a nematic phase with a long N* pitch and tight C* pitch in the C* phase. These new easily aligned DHFLC mixtures are discussed as well as their use in beam-steering devices that can benefit from analog optical response.
Ferroelectric (chiral) smectic C* liquid crystals have been shown to exhibit high speed, multistate electro-optic, display device and opto-electronic computing applications, particularly when incorporated into the surface stabilized ferroelectric liquid crystal (SSFLC) light valve. High polarizations and low viscosities are necessary to achieve the speeds desired in opto- electronic computing, waveguide, and fiber-optic applications. Use of the Boulder Model allows one to examine the most probable conformations of an FLC molecule in a hypothetical smectic C 'binding site' and thereby predict the sign and order of magnitude of the spontaneous polarization based on electronic and steric arguments for the particular chemical structure. By combining these high polarization materials with a low viscosity smectic C host, fast FLC mixtures can be formulated.
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