Hu Dou

A transflective blue-phase liquid crystal display with alternate electrodes

ABSTRACT A transflective polymer-stabilised blue-phase liquid crystal display (BP-LCD) with alternate electrodes is proposed. The alternate electrodes are composed of right triangle electrodes and slanted electrodes. To balance the optical phase retardation between the transmissive (T) and reflective (R) regions, the legs of the right triangle electrodes in the T region generate uniform horizontal electric field, the hypotenuses of the right triangle electrodes and slanted electrodes in the R region generate uniform oblique electric field. As result, the T and R regions obtain the same optical phase retardation. This display exhibits reasonably high transmittance, low operating voltage, wide viewing angle and well-matched voltage-dependent transmittance and reflectance curves. GRAPHICAL ABSTRACT

Blue-phase liquid crystal display with insulating protrusion

ABSTRACT In order to lower the saturation voltage and enhance the transmittance of in-plane switching blue-phase liquid crystal display (IPS-BPLCD), IPS-BPLCD with insulating protrusion is proposed. The single-protrusion (only set on the top of pixel electrode) and double-protrusion (set on the top of pixel and common electrodes) structures are investigated in this work. The potential distribution changes when the protrusion is used. There is a thicker transverse electric field in BPLC range, because the stronger electric field at the edges of the electrodes is decentralised into BPLC range. As a result, the saturation voltage is reduced from 36.3 V to 28.9 V when the double-protrusion structure is used, and transmittance is increased by ~20%. The contrast ratio is larger than 1000:1 in 60° viewing cone using a half-wave biaxial film. Both single-protrusion and double-protrusion structures have the uniform gamma curves at large oblique viewing angles. Moreover, the off-axis image distortion index is 0.1590 at 60º polar angle when zigzag electrodes are used. Graphical Abstract

A transflective polymer-stabilised blue-phase liquid display with partitioned wall-shaped electrodes

ABSTRACT A transflective polymer-stabilised blue-phase liquid crystal display (BP-LCD) with partitioned wall-shaped electrodes is proposed. The etched polymer layer contributes to balance the optical phase retardation between transmissive (T) and reflective (R) regions. The partitioned wall-shaped electrodes generate uniform and horizontal fields throughout the entire LC layer to induce isotropic-to-anisotropic transition in the blue-phase liquid crystal medium through Kerr effect. Consequently, the accumulated phase retardation along beam path is large, resulting in reasonable low operation voltage and high transmittance both in T and R regions. This approach enables the BP-LCD to be addressed by amorphous silicon thin-film transistors. Moreover, it exhibits wide viewing angle and a well-matched gamma curve. Graphical Abstract

Low voltage and high transmittance transflective blue-phase liquid crystal display with opposite polar electrodes

ABSTRACT A single-cell-gap transflective polymer-stabilised blue-phase liquid crystal display with opposite polar pixel electrodes on an etched substrate is proposed. In the proposed structure, the space between common electrodes is adopted as transmissive region, and the space above the common electrode is adopted as reflective region. By optimising the electrode parameters of the transmissive and reflective regions, well-matched voltage-dependent transmittance and reflectance curves can be obtained. In addition, the device has good performances of low operating voltage (~3.2 V), high optical efficiency and a wide viewing angle. GRAPHICAL ABSTRACT

A polarisation-independent blue-phase liquid crystal lens array using gradient electrodes

ABSTRACT A polarisation-independent blue-phase liquid crystal lens array using gradient electrodes is proposed. A high dielectric constant layer helps to smoothen out the horizontal electric field and reduce the operating voltage. With gradient electrodes and a planar top electrode, gradient electric fields are generated and lens-like phase profile is obtained. When the applied voltage is changed, the focal length of the lens can be tuned from ∞ to 5.94 mm. Besides, the simulation results show that the lens is insensitive to polarisation while keeping parabolic-like profile. Graphical Abstract

Low voltage blue-phase liquid crystal display with insulating protrusion sandwiched between dual-layer electrodes

ABSTRACT In order to lower the operating voltage of blue-phase liquid crystal display (BPLCD), a BPLCD with insulating protrusion, which is sandwiched between dual-layer electrodes, is proposed. There are four electrodes in this structure; thus, we investigate different driving methods to find a proper driving method. The effect of protrusion’s dielectric constant on operating voltage of the proposed BPLCD is explored under various electrodes’ parameters. As a result, the operating voltage of the proposed BPLCD with protrusion’s dielectric constant of 1,000 is 9.8 V, which is reduced by ~ 4.67× compared with that of conventional in-plane switching (IPS) BPLCD (45.8 V). Moreover, the zigzag electrode structure is adopted to reduce the large off-axis image distortion index. Besides, the azimuth distortion index is defined to describe the gamma shift between the minimum and maximum gamma shift curves at a certain polar angle. The results show that the off-axis image distortion index can be reduced to 0.0834, the azimuth distortion index is 0.0810 and the viewing cone of contrast ratio larger than 1,000:1 is over 50ºas the zigzag proposed BPLCD is used. Graphical Abstract

Single electro-optic curve for RGB colours in blue-phase liquid crystal display

ABSTRACT The double-layer penetration electrode structure is proposed to obtain the low-operating voltage blue-phase liquid crystal display (BPLCD) with single electro-optic curve for red-green-blue (RGB) colours in every pixel, which is more suitable for the field-sequential-colour display. The different influences of electrode’s parameters and driving methods on the electro-optical properties of the proposed BPLCD are investigated. The results demonstrate that the operating voltage can be reduced from 53.80 V to 23.00 V for red colour. Besides, the coincident voltage-dependent transmittance curves for RGB colours are obtained by adjusting the applied voltage of sub-electrode. Thus, RGB lights can pass through every pixel with single electro-optic curve, which is good for resolution enhancement and single gamma driving. Besides, the maximum gamma shift of the proposed BPLCD is less than 0.1099 at 60° polar angle for the red colour, and the gamma shift difference between red and blue colours is only 0.0542. If the high dielectric constant material is used as the protrusion, the operating voltage can be further decreased, which is close to that of the BPLCD with wall-shaped electrode structure. GRAPHICAL ABSTRACT

Transflective blue-phase liquid crystal display with polar opposite electrodes

ABSTRACT A submillisecond response, wide view and single-cell-gap transflective (TR) display employing a blue-phase liquid crystal is proposed. The device employs polar opposite in-plane switching (IPS) electrodes. To balance the optical phase retardation between transmissive (T) and reflective (R) regions, the IPS electrodes are formed with unequal gaps in the two regions. This display exhibits reasonably high optical efficiency and well-matched voltage-dependent transmittance and reflectance curves. Graphical Abstract

A multifunctional blue phase liquid crystal lens based on multi-electrode structure

ABSTRACT A blue phase liquid crystal (BPLC) lens with multifunction using multi-electrode structure and a dielectric layer with high dielectric constant is proposed. The refractive index of the BPLC can be changed flexibly in different regions. Some functional or technical requirements such as switch between positive and negative lenses can be achieved. The lens reveals a good parabolic refractive index distribution and focus adjustment capacity simultaneously. The applied voltage on the electrodes is regular and computable. To decrease the applied voltage of the proposed lens with a large diameter, a drive-type adopted Fresnel lens is introduced. GRAPHICAL ABSTRACT