Transflective Display Research Articles

Scattered-fields-induced tunable narrow resonance in low-index dielectric meta-lattices for transflective display

The development of a transflective display is important for reducing the energy consumption of an outdoor display-device. Currently, it is desirable to have a transflector which can be switched between its reflective and transparent states. The present work provides a novel yet simple route for the development of such a transflector based on one-dimensional (1D) meta-lattice systems. The system studied is shown capable of exciting tunable narrow resonance in the reflectance spectra through the generation of the scattered-field-induced polarizing-field in the system. Surprisingly, while most work on dielectric metasurface relies on high-index material, here it is found that the phenomenon can be achieved with common low-index material. Hence, it is a promising alternative for the development of future display technology with more economical operational cost.

Low voltage transflective blue-phase liquid crystal display with a non-uniform etching substrate**Project supported by the National Natural Science Foundation of China (Grant Nos. 61535007 and 61320106015) and the National Basic Research Program of China (Grant No. 2013CB328802).

A transflective polymer-stabilized blue-phase liquid crystal display (BP-LCD) with a non-uniform etching substrate is proposed. In-plane switching (IPS) electrodes on the bottom substrate are put on the different gaps, and the bottom substrate between the electrodes is etched into different depths in transmissive (T) and reflective (R) regions. This structure can balance the optical phase retardation in the two regions and is helpful to achieve well-matched voltag-dependent transmittance and reflectance curves. This transflective display has high optical efficiency, a wide viewing angle, and low operating voltage (approximately 6 V).

Single-cell gap polymer-stabilized fringe-field switching transflective liquid crystal display.

Transflective liquid crystal displays are highly desired for mobile devices because they can be operated either in transmissive mode, illuminated by backlight in dark ambient light conditions, or reflective mode, illuminated by ambient light in bright ambient light conditions. We developed a single-cell gap transflective display based on fringe-field switching. The display consists of transmissive and reflective subpixels whose operations are synchronized through polymer stabilization. This display has a high contrast ratio because the transmittance-voltage dependences of the two subpixels are similar (they are both in dark state at 0 V and in bright state at an applied voltage) and do not interfere with each other. It has the advantages of single-cell gap and no in-cell retarder and its manufacturing process is simple.

A Transflective Display Using Blue Phase Liquid Crystal

A combined fringe and in-plane switching (FIS) mode single-cell-gap transflective display using blue-phase liquid crystal (BPLC) is proposed. The structure makes use of the space above the pixel electrodes of this FIS mode as reflective regions and the space between pixel electrodes as transmissive regions. The structure which can be optimized to balance the optical phase retardation between transmissive region and reflective region with simple fabrication process exhibits relatively high optical efficiency and well matched voltage of transmittance and reflectance curves.

Liquid Crystal Polymer Networks: Preparation, Properties, and Applications of Films with Patterned Molecular Alignment

Monolithically ordered liquid crystal polymer networks are formed by the photoinitiated polymerization of multifunctional liquid crystal monomers. This paper describes the relevant principles and methods, the basic structure-property relationships in terms of mesogenic properties of the monomers, and the mechanical and optical properties of the polymers. Strategies are discussed to control the molecular orientation by various means and in all three dimensions. The versatility of the process is demonstrated by two examples of films with a patterned molecular order. It is shown that patterned retarders can be made by a two-step polymerization process which is successfully employed in a transflective display principle. A transflective display is a liquid crystal display that operates in both a reflective mode using ambient light and a transmissive mode with light coming from a backlight system. Furthermore, a method is discussed to create a patterned film in a single polymerization process. This film has alternating planar chiral nematic areas next to perpendicularly oriented (so-called homeotropic) areas. When applied as a coating to a substrate, the film changes its surface texture. During exposure to UV light, it switches from a flat to a corrugated state.

Tandem Organic Light-Emitting Diode and Organic Photovoltaic Device Inside Polymer Dispersed Liquid Crystal Cell

We have demonstrated a vertically stacked device consisting of organic photovoltaic device (OPV) and organic light-emitting diode (OLED) inside a polymer dispersed liquid crystal (PDLC) cell. In such a device, OLED and PDLC acted as transmissive- (T-) and reflective- (R-) mode, respectively, of a transflective display without the tradeoff of aperture ratio between R- and T-modes in a conventional transflective LC display. OPV functioned as the black background for PDLC operation and increased the contrast ratio of OLED. Electrical characteristics of OLED and OPV in the stacked device were nearly identical to their individual device, which showed the fabrication process had little effect on OLED and OPV performances. However, their optical properties showed a little degradation, coming from the multi-layer structure and hence the suitable optical cavity design was needed. Storage lifetime of OLED increased in the stacked device because LC material helped to prevent the water and oxygen attack. Driving voltage of PDLC increased due to the insertion of passivation layer upon the electrode which was used protect the OLED and OPV underneath.

Vertically Integrated Transflective Liquid Crystal Display Using Multi-Stable Cholesteric Liquid Crystal Film

The work demonstrates a switchable transflective liquid crystal display using a cholesteric liquid crystal (CLC) film as a switchable reflector. The planar and uniformly-lying helical (ULH) states of CLCs support the reflective and transmissive modes of the display, respectively. Both planar and ULH textures are stable states, and each can be switched to the other via the electro-hydrodynamic effect by applying a low-frequency (30 Hz) electrical field. A transflective display with a CLC as switchable reflector can be utilized in any currently used display mode, such as TN, MVA, and IPS. Such a display exhibits high display performance in both indoor and outdoor environments and low power consumption. It therefore has great potential to be used in portable information systems.

A transflective liquid crystal display using polymer stabilised vertical alignment mode

A transflective liquid crystal display using polymer-stabilised vertical alignment mode with fishbone-shaped electrode structure is proposed. Using the polymer stabilisation technique and patterned direction of pixel electrode structure, initial surface tilt angle and azimuthal angle can be well defined such that the liquid crystal is almost vertically aligned in the transmissive part while it has a certain pretilt angle that satisfies effective retardation of λ/4 with azimuthal direction of 45o with respect to the analyser in the reflective part. With optimisation of cell structures and surface tilt angles in the transmissive and reflective parts, a high performance transflective display showing excellent readability in any environment light conditions and single-gamma characteristic without using any retardation film or in-cell retarder can be achieved.

P‐85: A Novel Transflective Display Using Blue Phase Liquid Crystal

AbstractA In Plane Switching (IPS) mode single‐cell‐gap transflective display using blue‐phase liquid crystal (BPLC) is proposed. The novel structure makes use of the space above the electrodes of the IPS structure which contributes little to the total transmittance due to weak horizontal electric field as reflective region and the space between the electrodes as transmissive region. The shape of the electrodes is optimized to balance the phase retardation between the transmissive region and reflective region. This transflective structure exhibits relatively high optical efficiency and well matched driving voltage of both transmittance and reflectance curves.

Low Voltage and High Optical Efficiency Single-Cell-Gap Transflective Display Using a Blue-Phase Liquid Crystal

A single-cell-gap transflective display using a polymer-stabilized blue-phase liquid crystal is proposed. The periodic right triangle electrodes whose hypotenuses parallel to each other are formed. In the transmissive (T) region, the legs of the right triangle electrodes are opposite, which leads to a strong horizontal electric field. In the reflective (R) region, the hypotenuses parallel to each other, which results in a strong horizontal field component, which is uniformly distributed across the entire R-region. By optimizing the device parameters, well matched voltage-dependent transmittance and reflectance curves are achieved. This device exhibits low operating voltage (<;10 V), wide viewing angle, and high optical efficiency in both T- and R-regions. The potential application of the proposed device is emphasized.

P‐147: A Fast Response Time and Wide‐Viewing‐Angle Transflective Display Using Polymer‐Stabilized Blue‐Phase Liquid Crystal

AbstractA fast response time, wide viewing angle and single‐cell‐gap transflective display using a polymer‐stabilized blue‐phase liquid crystal is proposed. The transmissive region has an in‐plane wall‐shaped electrode while the reflective region has an in‐plane trapezoid electrode. The transmissive and reflective regions have similar gamma curves.

A single‐cell‐gap transflective liquid‐crystal display using different pretilt angles in transmissive and reflective regions

Abstract— A single‐cel l‐gap transflective liquid‐crystal display with two types of liquid‐crystal alignment based on an in‐plane‐switching structure is proposed. The transmissive region is almost homeotropically aligned with the rubbed surfaces at parallel directions while the reflective region has a homeotropic liquid‐crystal alignment. For every driving voltage for a positive‐dielectric‐anisotropy nematic liquid crystal, the effective cell‐retardation value in the transmissive region becomes larger than that in the reflective region because of optical compensation film which is generated by low‐pretilt‐angle liquid crystal in the transmissive region. Under the optimization of the liquid‐crystal cell and alignment used in the transmissive and reflective areas, the transmissive and reflective parts have similar gamma curves. An identical response time in both the transmissive and reflective regions and a desirable viewing angle for personal portable displays can also be obtained.

Low Voltage and High Transmittance Transflective Display Using Polymer-Stabilized Blue-Phase Liquid Crystal

A fast response time, wide viewing angle, and single-cell-gap transflective display using polymer-stabilized blue-phase liquid crystal is proposed. The transmissive region has an in-plane wall-shaped electrode while the reflective region has an in-plane trapezoid electrode. Both of the electrodes generate a strong horizontal field, resulting in a low operating voltage and high transmittance and reflectance. In every driving voltage, the effective cell retardation value in the transmissive region is larger than that in the reflective region, so that the transmissive and reflective regions have similar gamma curves.

A Single-Cell-Gap Transflective Display Using a Blue-Phase Liquid Crystal

A single-cell-gap transflective display using a blue-phase liquid crystal (BP-LC) is proposed. In order to balance the optical phase retardation between transmissive (T ) and reflective (R) regions, in-plane protrusion electrodes are formed in both T and R regions on the bottom substrate, and only in the T region on the top substrate. The device exhibits well-matched voltage dependent transmittance and reflectance curves, a low operating voltage, and a wide viewing angle.

Transflective display using a polymer-stabilized blue-phase liquid crystal

A wide view, submillisecond response, and single-cell-gap transflective display using a blue-phase liquid crystal (BPLC) is proposed. To balance the optical phase retardation between transmissive (T) and reflective (R) regions, in-plane protrusion electrodes are formed with different gaps in the two regions. This display exhibits reasonably high optical efficiency and well matched voltage dependent transmittance and reflectance curves. Using biaxial films and broadband wide-view circular polarizers, the viewing angle with 100:1 contrast ratio is obtained over the entire viewing cone in the T region, and 10:1 over 50 degrees in the R region. The potential application is emphasized.

Single cell-gap transflective liquid crystal device utilizing continuous director rotation with different twist angle in the fringe-field switching mode

In this paper, a single cell-gap and single gamma transflective liquid crystal displays (LCDs) associated with fringe-field switching (FFS) device is proposed. The device utilizes unique characteristic of the FFS device in which the twist angle of LC director is dependent on electrode position in on state. With optimization of pixel electrode width and distance between them, the LC director can be rotated about 22.5° and 45° of twist angles depending on electrode positions. Consequently, the parts with low and high twist angle could be played for the reflective ( R) and transmissive ( T) regions respectively, realizing a high image quality transflective display.

Sunlight Readable Fast-Response Transflective LCDs by Horizontal Electric Fields

Two single-cell-gap transflective display devices with vertically aligned positive dielectric anisotropy liquid crystal driven by horizontal electric fields are proposed. In these displays, patterned reflectors are located at transmittance-inefficient regions to serve as reflective mode. These displays exhibit fast response time, high transmittance, and wide view with optical compensation. Potential applications of these displays for sunlight readable mobile devices are emphasized.

A Fast Transflective Ferroelectric Liquid Crystal Display with Gray Scales in a Single Gap Geometry with Dual Transverse Electric Fields

A transflective display with high speed and gray scale capability is demonstrated using a vertically aligned deformed helix ferroelectric liquid crystal (VA-DHFLC) mode in a single gap geometry. In order to compensate the optical path difference between transmissive (T) and reflective (R) regions, dual types of transverse electric fields are produced from in-plane electrodes prepared on two substrates in T regions and on only one substrate in R regions. The VA-DHFLC mode employed in such electrode configuration provides several unique features such as defect-free alignment over large area, fast response, and gray scale capability without hysteresis.

A single-gap transflective liquid crystal driven by fringe and vertical electric fields

A single-gap transflective liquid-crystal display driven by a fringe electric field in the transmissive (T) region and a vertical electric field in the reflective (R) region was designed. In the device, a homogeneously aligned liquid crystal (LC) rotates almost in plane by a fringe field in the T-region whereas the LC tilts upwards by a vertical field in the R-region. A high surface pre-tilt angle of the LC in the R-region is achieved through polymerization of an UV curable reactive mesogen monomer at the surfaces and thus the effective cell retardation in the R-region becomes half of that in the T-region. Consequently, a transflective display driven by a vertical and a fringe electric field with a single cell gap and single gamma curves is realized.

37.3: Smart Transflective Display Integrated with PDLC and OPV‐Embedded‐OLED

AbstractWe demonstrated a hybrid transflective device by vertically integrating a PDLC and an OLED with OPVas the reflective and transmissive mode, respectively. Such an OPV in an OLED absorbs light and converts into electrical power, which reduces the power consumption and also acts as the integrated sensor.