Field Sequential Color Liquid Crystal Research Articles

Deep learning-based real-time driving for 3-field sequential color displays with low color breakup and high fidelity.

Field sequential color liquid crystal displays (FSC-LCDs) are promising for applications needing high brightness and high resolution because removing color filters brings three times the light efficiency and spatial resolution. In particular, the emerging mini-LED backlight introduces compact volume and high contrast. However, the color breakup severely deteriorates FSC-LCDs. Concerning color breakup, various 4-field driving algorithms have been proposed at the cost of an additional field. In contrast, although 3-field driving is more desired due to fewer fields used, few 3-field methods that can balance image fidelity and color breakup for diverse image content have been proposed. To develop the desired 3-field algorithm, we first derive the backlight signal of one multi-color field using multi-objective optimization (MOO), which achieves a Pareto optimality between color breakup and distortion. Next, considering the slow MOO, the MOO-generated backlight data forms a training set to train a lightweight backlight generation neural network (LBGNN), which can produce a Pareto optimal backlight in real-time (2.3 ms on GeForce RTX 3060). As a result, objective evaluation demonstrates a reduction of 21% in color breakup compared with currently the best algorithm in color breakup suppression. Meantime, the proposed algorithm controls the distortion within the just noticeable difference (JND), successfully addressing the conventional dilemma between color breakup and distortion for 3-field driving. Finally, experiments with subjective evaluation further validate the proposed method by matching the objective evaluation.

Color breakup suppression based on global dimming for field sequential color displays using edge information in images.

Considering the high complexity of local dimming backlight that is necessary to effectively suppress color breakups for field sequential color liquid crystal displays (FSC-LCDs), a global dimming-based solution is proposed. This solution involves considering that the color breakups mainly occur at object edges of an image. By introducing an algorithm to present the edge information in a single field, evaluating color breakup performances, and experimentally verifying based on a 240-Hz LCD, lighter color breakups are revealed compared with mainstream local dimming-based solutions. Therefore, the proposed solution can achieve FSC-LCDs with better performance and practicality for advanced display applications.

Angularly positioned LED-based spatial-temporal color separation system

This study proposes a two-field driving scheme for field sequential color liquid crystal displays (LCDs) without color filters. The proposed scheme is based on angularly positioned color LEDs. In each field, the angular rays of two colors are collimated by a collimation lens, redirected by a light guide, and converged by a cylindrical-lens array to map into corresponding sub-pixel positions to efficiently display color images. The three main advantages of this approach are the elimination of dye color filters, high feasibility using conventional ultra-precision machining processes, and a larger color gamut.

高分子安定化による強誘電性液晶の単安定化−時分割カラー表示方式の次世代液晶ディスプレイ開発に向けて−

強誘電性液晶は高速応答，広視野角，双安定性などの特徴を有し，その高速応答性を利用して時分割カラー表示が可能となるため次世代液晶ディスプレイ材料として期待されている。しかし，双安定性は中間調・フルカラー表示を困難とさせる。そのため，単安定化が強く求められ，その手法に高分子安定化がある。本研究では，重合条件が比較的簡素であるSmA相重合による高分子安定化に着目し，単安定化に向けて材料や高分子濃度，セル厚，重合エネルギーなどの作製条件について検討を行った。その結果，高分子濃度は高く，セル厚は厚いほうが単安定化に適していることが明らかになった。さらに，単安定化度は重合エネルギーに依存し，単安定性を実現するためには適切な値があるとわかった。また，モノマー種は高分子安定化力に強く影響することがわかり，アルキルスペーサーは短く，分子サイズの大きいモノマーほど液晶分子の配向を強く安定化できることがわかった。

Pseudo Zero-Dimension Dimming for Power Reduction in Field Sequential Color Liquid Crystal Display Systems

Expensive hardware is required by the conventional two-dimensional (2-D) light-emitting diode (LED) dimming technique to obtain high-contrast and low-power in the field sequential color (FSC) technique. Thus, based on real-time image data, the pseudo zero-dimension (0-D) LED dimming technique is proposed to further reduce power dissipation in the D-FSC technique, which allows the intelligent selection of an adequate color sequence. The multi-liquid crystal and backlight (LC/BL) algorithm utilizes the D-FSC technique in temporal and spatial domains. It not only utilizes the pseudo 0-D technique to effectively reduce the color breakup (CBU) effect without greatly increasing frame rate, but also to reduce power consumption. On the backlight module, CBU suppression can be substantially improved and power dissipation can be reduced by at least 12.5%. Power consumption can also be further reduced through the re-dimming improvement in the proposed pseudo 0-D dimming technique.

Metal-Induced Continuous Zonal Domain (CZD) Polycrystalline Silicon Thin-Film Transistors and Its Application on Field Sequential Color Liquid Crystal Display

Metal induced polycrystalline silicon (poly-Si) films composing of continuous zonal domain (CZD) have been obtained through pre-defined crystalline nucleation lines (CNL). The crystallization process is precisely controllable and repeatable. P-channel thin-film transistors (TFTs) built on CZD poly-Si present high performance and high uniformity. Based on this CZD poly-Si TFT technology, which provides fast addressing characteristics and a large aperture ratio, together with a fast liquid crystal mode, a field sequential color liquid crystal display (FSC-LCD) prototype is designed and fabricated successfully. Excellent color purity and fast moving image can be obtained.

A Highly Accurate Measurement of Liquid Crystal Material and Device Parameters

A highly accurate measurement method for the refractive indices of liquid crystal materials, the alignment distribution and the surface polar anchoring strength was devised by considering the multiple reflections and the interferences in the LC cell. Based on the accurate evaluation of LC devices, we developed the high-quality field sequential color liquid crystal display with a wide viewing angle and high contrast ratio.

Improvement of Transmittance and Viewing Angle of Optically Compensated Bend Mode Liquid Crystal Display Using Wide-Viewing-Angle Circular Polarizer

A field sequential color liquid crystal display (LCD) has been developed using an optically compensated bend (OCB) mode liquid crystal cell and a light-emitting diode backlight. Application of a wide-viewing-angle- and wide-band-type circular polarizer realized a wide-viewing-angle and high-transmittance OCB-mode LC cell. In this paper, we describe the principle of the optical compensation and the fundamental characteristics of an advanced OCB-mode LCD.

Design Constraints on FSC LCD

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Design constraints on field-sequential color liquid crystal displays (LCDs) are proposed and compared with those of conventional color filter LCDs. Application of these constraints to the design of LCD screens is demonstrated. </para>