Recently, 'Liquid crystal display (LCD) vs. organic light-emitting diode (OLED) display: who wins?' has become a topic of heated debate. In this review, we perform a systematic and comparative study of these two flat panel display technologies. First, we review recent advances in LCDs and OLEDs, including material development, device configuration and system integration. Next we analyze and compare their performances by six key display metrics: response time, contrast ratio, color gamut, lifetime, power efficiency, and panel flexibility. In this section, we focus on two key parameters: motion picture response time (MPRT) and ambient contrast ratio (ACR), which dramatically affect image quality in practical application scenarios. MPRT determines the image blur of a moving picture, and ACR governs the perceived image contrast under ambient lighting conditions. It is intriguing that LCD can achieve comparable or even slightly better MPRT and ACR than OLED, although its response time and contrast ratio are generally perceived to be much inferior to those of OLED. Finally, three future trends are highlighted, including high dynamic range, virtual reality/augmented reality and smart displays with versatile functions.

/pdf/liquid-crystal-display-and-organic-light-emitting-diode-5b9d3ky1k3.pdf

Liquid crystal display and organic light-emitting diode display: present status and future perspectives

An embodiment of the present invention provides a method of driving a liquid crystal display device including a liquid crystal panel, and a backlight assembly providing light to the liquid crystal panel by a field sequential driving method, the method includes: displaying an image, at the liquid crystal panel and the backlight assembly, by time-dividing two frames into five sub-frames, wherein when images are displayed in the two frames, images of a first frame and a second frame of the two frames share one blue light.

Liquid crystal display device and driving method thereof

We analyze the performance of high dynamic range liquid crystal displays (LCDs) using a two-dimensional local dimming mini-LED backlight. The halo effect of such a HDR display system is investigated by both numerical simulation and human visual perception experiment. The halo effect is mainly governed by two factors: intrinsic LCD contrast ratio (CR) and dimming zone number. Based on our results, to suppress the halo effect to indistinguishable level, a LCD with CR≈5000:1 requires about 200 local dimming zones, while for a LCD with CR≈2000:1 the required dimming zone number is over 3000. Our model provides useful guidelines to optimize the mini-LED backlit LCDs for achieving dynamic contrast ratio comparable to organic LED displays.

High dynamic range liquid crystal displays with a mini-LED backlight.

J Soc Inf Display. 2019;27:387–401. Abstract We review the emerging mini/micro–light‐emitting diode (LED) displays featuring high dynamic range and good sunlight readability. For mini‐LED backlit liquid crystal displays (LCDs), we quantitatively evaluate how the device contrast ratio, local dimming zone number, and local light profile affect the image quality. For the emissive mini/micro‐LED displays, the challenges of ambient contrast ratio and size‐dependent power efficiency are analyzed. Two figure‐of‐merits are proposed for optimizing the optical and electrical performances of mini/micro‐LED displays.

Prospects and challenges of mini-LED and micro-LED displays

Abstract Liquid crystal displays (LCDs) and photonic devices play a pivotal role to augmented reality (AR) and virtual reality (VR). The recently emerging high-dynamic-range (HDR) mini-LED backlit LCDs significantly boost the image quality and brightness and reduce the power consumption for VR displays. Such a light engine is particularly attractive for compensating the optical loss of pancake structure to achieve compact and lightweight VR headsets. On the other hand, high-resolution-density, and high-brightness liquid-crystal-on-silicon (LCoS) is a promising image source for the see-through AR displays, especially under high ambient lighting conditions. Meanwhile, the high-speed LCoS spatial light modulators open a new door for holographic displays and focal surface displays. Finally, the ultrathin planar diffractive LC optical elements, such as geometric phase LC grating and lens, have found useful applications in AR and VR for enhancing resolution, widening field-of-view, suppressing chromatic aberrations, creating multiplanes to overcome the vergence-accommodation conflict, and dynamic pupil steering to achieve gaze-matched Maxwellian displays, just to name a few. The operation principles, potential applications, and future challenges of these advanced LC devices will be discussed. 

https://www.nature.com/articles/s41377-022-00851-3.pdf

Advanced liquid crystal devices for augmented reality and virtual reality displays: principles and applications

A high dynamic range liquid crystal display (HDR-LCD) can enhance the contrast ratio of images by utilizing locally controlled dynamic backlight. We studied the HDR-LCD as a dual-panel display: a backlight module and a liquid crystal (LC) cell. As the gamma of the LC signal, the backlight module was also endowed with a gamma function to control the contrast ratio of HDR images. The inverse of a mapping function (IMF) method proposed as a dynamic gamma mapping curve for the backlight module, has been demonstrated to further improve in HDR image quality. By implementing the IMF method on a HDR-LCD TV with 88 backlight zones, the image contrast ratio can reach while maintaining high brightness, clear image detail, and an average power reduction of 30%.

https://ir.nctu.edu.tw:443/bitstream/11536/8765/1/000259552500005.pdf

Dynamic Backlight Gamma on High Dynamic Range LCD TVs

A backlight module including a first light guide plate, a first light source, a second light guide plate, and a second light source. The first light guide plate includes a first side, a second side opposite to the first side, and a first surface with a micro-groove structure. The first light source is disposed on the first side of the first light guide plate. The second light guide plate is disposed on the first light guide plate, and includes a third side, a fourth side opposite to the third side, and a second surface with a micro-groove structure. The fourth side and the second side are located at the same side. The second light source is disposed on the fourth side of the second light guide plate.

Backlight module for 3D display device and method for displaying 3D images utilizing the same

A thin film transistor disposed on a substrate is provided. The thin film transistor includes a gate, a semi-conductive layer, a gate insulator, a source and a drain. The gate insulator is located between the gate and the semi-conductive layer. A light shows a specific color after passing through the gate insulator. The source and the drain are disposed on the semi-conductive layer. A pixel structure and a liquid crystal display panel having the pixel structure are also provided. The liquid crystal display panel can display colorful images without disposing a color filter array additionally so that the manufacturing process of the liquid crystal panel is simple and the manufacturing cost of the liquid crystal panel is low.

Thin film transistor, pixel structure and liquid crystal display panel

A cumulative function of image is obtained according to its gray levels of pixels. This function is then mapped to obtain a backlight modulation function according to a reference line. The backlight brightness provided for different regions of the liquid crystal display are decided by the backlight modulation function while displaying the images.

Backlight control method for high dynamic range LCD

A semiconductor structure and a fabricating method thereof are provided. The fabricating method includes forming a gate, a source, and a drain on a substrate and forming an oxide semiconductor material between the gate and the source and drain. The oxide semiconductor material is formed by performing a deposition process, and nitrogen gas is introduced before the deposition process is completely performed, so as to form oxide semiconductor nitride on the oxide semiconductor material.

Han-Ping D. Shieh

Papers

Dynamic Backlight Gamma on High Dynamic Range LCD TVs

Backlight module for 3D display device and method for displaying 3D images utilizing the same

Thin film transistor, pixel structure and liquid crystal display panel

Backlight control method for high dynamic range LCD

Semiconductor structure and fabricating method thereof