Alexander Muravsky

Optical rewritable liquid-crystal-alignment technology

— A new optical rewritable (ORW) liquid-crystal-alignment technology has been developed to create a display and to demonstrate its maturity and potential. ORW displays have no electrodes and use polarizers as substrates. The display requires no photolithography on plastic. Its simple construction secures durability and low cost for mass production. The on-screen information is optically changed in a writing unit that consists of an LCD mask and an exposure source that is based on LEDs, low power, and low cost in comparison with Hg lamps or lasers. A high contrast image can be easily written, viewed, and rewritten through a polarizer, while the multi-stable gray-level image requires zero power to maintain the image. Reconfigurable LC alignment using ORW technology best suits plastic-card displays as well as for LC photonics and various one-mask processes of patterned LC-alignment applications.

Light Printing of Grayscale Pixel Images on Optical Rewritable Electronic Paper

The new principle of electronic paper that can display two-dimensional (2D) or even stereoscopic three-dimensional (3D) images was developed by us. We review the structure of the display unit that is the light printable rewritable matter with polarization dependent gray scale. It consists of one or two liquid crystal displays based on optical rewritable (ORW) technology. ORW display uses bare plastic or polarizers as substrates, while no conductor is required. Continuous grey image on ORW e-paper maintains proper performance even when the device is bent. The image is changed by light printer. We discuss and experimentally verify the possible design of the light printer device based on polarization rotation. Alternative designs based on twist nematic (TN) or ferroelectric liquid crystals (FLC) operational element are also suggested. Simple construction provides durability and low cost of the ORW e-paper concept, while amazing possibility of 3D picture on ORW electronic paper is principally proved.

New properties and applications of rewritable azo-dye photoalignment

— The rewritable azo-dye photoalignment (ORW) of liquid crystals (LCs) for application in optical rewritable electronic paper has been investigated. It was observed that a periodic change in the azimuthal aligning direction with polarized UV light (365 nm) brings about homeotropic alignment, while utilization of visible light (450 nm) does not affect the LC tilt angle. The wavelength dependence of the ORW photoalignment result and the behavior of the photoinduced anisotropy was explored. The dark amplification of film anisotropy after exposure was observed, which is believed to be the relaxation process related to hydrogen bonding in azo-dye film. New material, CD1, for azo-dye rotation photoalignement that possesses a high azimuthal anchoring energy (about 2 × 10−4 J/m2) was found.

Novel polymer as liquid crystal alignment material for plastic substrates

Implementation of the roll-to-roll (R2R) process and printable organic electronics realizes the cost reduction potential of liquid crystal displays (LCDs) on plastic substrates. These innovative technologies put a strong limitation on the chemistry and temperature treatment of the LC alignment material applied at the solid–liquid interface inside the LCD. Alignment material is the last uniform layer deposited on each of the substrates before assembling and sealing of the whole display sandwich. Deposition from an aggressive solvent, vacuum deposition or a high baking temperature can not only destroy the complex composite structure of the electronics but can also affect the material properties of the substrate. We developed a new type of polymer alignment material, B-15, which can be deposited from a non-aggressive solvent (ethyl/butyl acetate) on top of the wide range of organic layers (including UV-curable materials and TAC films of plastic polarizer) without barrier layers for chemical protection. B-15 is suitable for the R2R process for only short-time treatment operations: 5 min baking at 90 °C is sufficient to remove the residual solvent and hard baking is not required. First, the rubbing process produces an alignment direction on the surface with the azimuthal anchoring energy over 10−4 J m−2. Next, non-polarized light exposure with a 254 nm Hg line induces photopolymerization, which also shifts the absorption peak far below the 300 nm wavelength. Thus B-15 is a highly photostable alignment material possessing null absorption in both the UV-A and the VIS ranges.

Grayscale Generation and Stabilization in Ferroelectric Liquid Crystal Display

Intrinsic grayscale generation and stabilization in ferroelectric liquid crystal display (FLCD) have been proposed and investigated. Study of the FLC samples shows that the switching process takes place through the formation and evolutions of domains formation. Dynamic current and electrooptical response in FLC testing cell are discussed as a criterion of memorized grayscale generation for FLC display. Grayscale stability for different crosstalk effects under a passive multiplex driving scheme is demonstrated. Passive 160 160 multiplex addressing photo-aligned 5- reflective FLCD with a high contrast and four memorized grayscale levels is developed.

Optical Rewritable Electronic Paper

We developed new principle of electronic paper that is one side (for 2D image) or double side (for stereoscopic 3D image) light printable rewritable matter with polarization dependent gray scale. It consists of one or two liquid crystal displays based on Optical Rewritable (ORW) technology, which is the development of rotation azo-dye photoalignment. Each ORW display uses bare plastic or polarizers as substrates. The conductor is not required, as the image is formed by rewritable states of azimuthal direction, which results in 2D pattern of the liquid crystal twist angle. Continuous grey image maintains proper performance even when the device is bent. Simple construction provides durability and low cost, thin substrates minimize parallax for 3D image. Fluorescent dye dopant of liquid crystal partly absorbs light in blue and re-emit in green specter range improving photopic reflection and enhancing color of the ORW e-paper.

60.1: Optical Rewritable Electronic Paper with Fluorescent Dye Doped Liquid Crystal

optical rewritable (ORW) electronic paper is the joint result of advanced photoalignment of liquid crystals, optical engineering and flexible LCD technologies. We report improvement of both dark and bright states of reflective ORW e-paper by doping LC with fluorescent dye, which absorb blue light & emit in green with high efficiency. 1. Introduction vast term of electronic paper comprises various perspective display techniques, which aims to store and display information generated by computer on a light weight thin flexible and robust, paper-like carrier with good brightness, high contrast and full viewing angle. In the contrast to flexible or rollable display, the frame rate is not the proper merit of e-paper performance, as the environmental, paper saving, aspect suggest competition not with the flat panel displays but the paper itself. Here the ultra low power consumption is highly desired, meaning reflective operation. It can be done by versatile means with the preference to the usability, durability and low paper-like cost. The progress in LC photoalignment and our recent development of optical rewritable (ORW) e-paper (1) have made it possible to separate e-paper display-unit (2) and driving optoelectronics part (3). That results into significant reduction of complexity of our ORW e-paper structure, having made device properties and cost both paper-like.

P-137: Photoaligned Transflective Liquid Crystal Display with Single Cell Gap using OCB and Low Twist Nematic Modes

Transflective liquid crystal display (LCD) with single cell gap consisting optically compensated bend (OCB) and low twist nematic modes has been studied. Since no double cell gap structure is included in the configuration, the fabrication process is easy and only one more step UV exposure is needed during photoalignment process to produce domains. Based on this new configuration, a transflective LCD with high brightness and high contrast could be obtained.

P-232L: Late-News Poster: New Results on Bistable Photoaligned Ferroelectric LCDs: Grey Scale Generation, Stabilization and Passive Driving Scheme

The principles for intrinsic greyscale generation and stabilization of bistable photoaligned FLCD are discussed and investigated. In order to realize these principles, the passive matrix driving scheme for FLCD is proposed and studied. Passive 160×160 matrix addressing photoaligned 5μm reflective FLC display (48mm×46mm) with high contrast and 4 memorized grey scale levels is demonstrated. Images can be saved for very long time without any power supply. 15V driving voltage is only needed to refresh information, which is impressive and desirable for low power consumption display such as PDA, e-paper etc.

P‐153: Flexible Photoaligned Optically Rewritable LC display

Flexible optically rewritable reflective TN LC display based on photoalignment technology has been demonstrated. The rewritable display does not require any electronic scheme, power supply, or conductive layers, when operating. Such a display can erase and write images for many times because of LC alignment reorientation onto one photoalignment layer under exposure of a polarized UV light. The image can be saved with a very high contrast for a long time.