Conventional LCD Research Articles

18‐2: A Novel Design for Reconfigurable Intelligent Surfaces (RIS) with Thin Liquid Crystal Layer for Wireless Communications

This paper proposes a proof‐of‐concept design for RIS made with liquid crystals (LC) and Corning glass for wireless communication applications. The proposed RIS concept consists of the specially designed copper‐coated glass substrates and liquid crystal materials that were filled in between two glass substrates. The LC layer exists between the upper and lower Corning glass sheets, and it is 20 μm thick. Although the 20 μm cell‐gap is very thin compared to the operating frequency (it is more than 100 μm in previous research), more than the 180° phase difference was achieved by applying 10 V in the designed frequency band. Our proposed concept can improve wireless communication coverage by reflecting incident electromagnetic waves in the desired direction to secure a propagation path by simply changing the alignment of LC molecules under different driving voltages. Also, conventional LCD manufacturing technology can significantly reduce costs and support larger sized capabilities, compared to incumbent semiconductor‐based electronics and printed circuit board (PCB) processing.

The Effect of Interocular Contrast Differences on the Appearance of Augmented Reality Imagery

Augmented reality (AR) devices seek to create compelling visual experiences that merge virtual imagery with the natural world. These devices often rely on wearable near-eye display systems that can optically overlay digital images to the left and right eyes of the user separately. Ideally, the two eyes should be shown images with minimal radiometric differences (e.g., the same overall luminance, contrast, and color in both eyes), but achieving this binocular equality can be challenging in wearable systems with stringent demands on weight and size. Basic vision research has shown that a spectrum of potentially detrimental perceptual effects can be elicited by imagery with radiometric differences between the eyes, but it is not clear whether and how these findings apply to the experience of modern AR devices. In this work, we first develop a testing paradigm for assessing multiple aspects of visual appearance at once, and characterize five key perceptual factors when participants viewed stimuli with interocular contrast differences. In a second experiment, we simulate optical see-through AR imagery using conventional desktop LCD monitors and use the same paradigm to evaluate the multi-faceted perceptual implications when the AR display luminance differs between the two eyes. We also include simulations of monocular AR systems (i.e., systems in which only one eye sees the displayed image). Our results suggest that interocular contrast differences can drive several potentially detrimental perceptual effects in binocular AR systems, such as binocular luster, rivalry, and spurious depth differences. In addition, monocular AR displays tend to have more artifacts than binocular displays with a large contrast difference in the two eyes. A better understanding of the range and likelihood of these perceptual phenomena can help inform design choices that support high-quality user experiences in AR.

P‐92: A Fast Response Time FFS‐LCD with Novel Electrode Design

In this paper, an FFS LCD is developed which contains ITO3 electrode other than the ITO2 pixel electrode, and the ITO3 electrode has a separate timing signal. This configuration can optimize response time by increasing the electric field strength of LC cell. In addition, the transmittance for the LCD using novel electrode design is also improved compared to conventional LCD. This electrode design will have opportunities for applications in the field of gaming and virtual reality displays.

Real-Time 2D-to-3D Conversion for Television Broadcasting Based on Embedded System

In this article, we present an efficient 3-D display technique that employs current 2-D television (TV) channels. First, a gradient background depth is generated for the still region. To create a stereo effect, multiple objects are detected and segmented using the binary format. Object depth is estimated according to the object size and its location. Depth value is assigned as a proportion of the object size using the linear quantitative method. Each object size is calculated and its depth value is proportional to the size parameter. If an object is the largest one and is located in the central region, the maximum depth value is assigned. For real-time implementation, dual advanced RISC machine (ARM) cores perform the task using the algorithm of the proposed stereo conversion. Our results show that a low-cost embedded system can perform the proposed 3-D algorithm, with a processing time of 43 ms per frame. The signal from a TV channel can be sampled and converted to a 3-D format display on a conventional LCD screen.

54.5: Wide Viewing Angle Vertical Alignment Photoluminescent LCD

Owing to the angular dependent birefringence, liquid crystal displays are subject to viewing angle issues. Various wide viewing angle LCD technologies have been developed to solve the problem. The concept of photoluminescent LCD (PLLCD) as a promising solution for wide viewing LCD has been proposed more than two decades ago. Recently quantum dot photo‐luminescent material has been applied in LCD TV in the form of backlight color enhanced film (QDEF). More recently quantum dot emissive color converter which essentially changes the LCD to becoming an emissive display is also proposed. Here we report our attempt to include a photo‐luminescent film in front of a conventional LCD to enhance the viewing angle and the challenges encountered.

46.1: Invited Paper: High Performance Micro LED Display Based on Complementary Metal‐Oxide‐Semiconductor Backplane by using Digital Driving Technology

It is well known that the properties of micro LED display have the higher contrast ratio, higher brightness, high reliability, and much faster response time than conventional LCD and OLED displays. We demonstrate a prove of concept (POC) pico‐projector prototype with a F/0.9 camera lens, and green micro LED panel, and digital driving board. The lumen output from POC pico‐projector is only about 1 Lumen. We calculate that if the POC pico‐projector prototype is with much higher brightness, larger size micro LED panel, plus micro lens array, and three panels optical system, it should be able to achieve 500~600 Lumen pico‐projector.

P‐38: A New Pixel Architecture for Low‐Power LCDs with Oxide TFTs

A new memory‐in‐pixel (MIP) circuit using oxide thin‐film transistors (TFTs) to achieve low power consumption is proposed. The display employing the proposed pixel circuit can greatly reduce the power consumption due to extremely low leakage current of oxide semiconductor TFTs. By fabricating the circuit with oxide TFT process, the circuit performance under continuous operation is successfully verified without additional programming. The power consumption in the panel (except backlight) can be reduced to 0.03% of that of conventional LCD.

51‐1: Novel Pixel Structure for 8K QUHD LCD Panel with the Enhanced Optical Performances

We report on novel pixel architecture for improving the transmittance and reducing the gamma distortion to minimize the color shift in an 8K QUHD LCD panel with the hG‐2D technology. In our LCD panel, each pixel has a unique electrode structure which is mixed with conventional micro‐slits and reversed those. It is named “multi‐domain reversed‐slit VA mode (MRS‐VA)”. This MRSVA‐LCD has the excellent transmittance by matching the LC distortions on the vertical electrode and two data lines which is asymmetrically positioned. Besides, by shielding the LC distortion line at the oblique viewing angle, the gamma distortion can be effectively suppressed. Through our pixel structure, superior performances to conventional LCD could be clearly proved (GDI value: 0.345 and panel transmittance (T): 3.7%). Additionally, by demonstrations of overcoming the crosstalk and bruising defects, we demonstrated that MRSVA‐LCD could be applied to the commercial 8K panels manufactured by the mass production.

44‐2: Distinguished Paper: A Full Integration of Electromagnetic Resonance Sensor and Capacitive Touch Sensor into LCD

We have developed a transmissive and reflective LCD which integrates electromagnetic resonance and capacitive touch sensors using existing in‐cell process. This technology has a good SNR of 42.5dB for electromagnetic resonance pen sensing and contributes the added benefits for thin design, lightweight panel, compared to conventional LCD techniques.

Computational imaging enables a “see-through” lens-less camera

Conventional cameras obscure the scene that is being recorded. Here, we place an image sensor (with no lens) on the edge of a transparent window and form images of the object seen through that window. This is enabled first, by the collection of scattered light by the image sensor, and second, by the solution of an inverse problem that represents the light scattering process. Thereby, we were able to form simple images, and demonstrate a spatial resolution of about 0.1 line-pairs/mm at an object distance of 150mm with depth-of-focus of at least 10mm. We further show imaging of two types of objects: an LED array and a conventional LCD screen. Finally, we also demonstrate color and video imaging.

P‐51: A New Display System for 8K OLED TV Using 4K Timing Controllers

To drive 8K display system, it requires 4 times of information data processing than UHD (4K) Timing Controller (TCON). 8K display system is easy to use 4K TCONs because it is difficult to implement on one‐chip due to size issue. To drive conventional 8K LCD Display system, 4K TCON application was adopted. One master TCON was controlling the rest of 3 slave TCONs, and each 4K image data was able to express at the same time. However, multiple issues arise from when four of 4K TCONs are combined together. Thus, to solve the issues, display system to drive the 8K OLED TV panel using five control ICs is proposed.

31.2: High PPI Micro‐LED Display Based on PWM Technology

Micro‐LED is well known for the backlights to liquid crystal displays with proven high luminous efficiency, low cost, and long lifetime. As technology progresses, LED became small enough as a self‐emissive display pixel. Compared to conventional LCD and OLED, Micro‐LED renders higher contrast ratio, brighter, and much faster response time. The technology consists of LED epitaxy, LED chip process, LED transfer process, silicon backplane electronics, and driver systems.

Quantum Dot Based Enhancement or Elimination of Color Filters for Liquid Crystal Display

The feasibility of quantum dot (QD)-based silicone composites as suitable candidates, in terms of down conversion efficiency, for the replacement or the enhancement of color filters in high-brightness liquid crystal displays is investigated for the first time. It is demonstrated that the replacement of color filters (CFs) with a full color conversion QD composites can lead to an 86.16% enhancement in energy efficiency over the conventional LCD with phosphor-converted white light-emitting diodes and RGB CFs as backlighting. A potential second-type technology utilizing QD-on-CF for color generation is also investigated, and it is found that the energy efficiency enhancement can reach 86.86%. In addition to QDs, the state-of-art red and green phosphors are also investigated for the purpose of enhancement of color filters in LCD displays in terms of down conversion efficiency, and the result shows a 105.78% enhancement in overall down conversion efficiency. The energy efficiency of QD-based color conversion composites can be further improved by optimization of QD dispersion in the resin, which makes them more suitable replacement for color filters in LCDs due to some intrinsic limitations in phosphor materials.

67‐4: Wide‐color‐gamut LCDs with Vivid Color LED Technology

A Vivid Color LED with an ultra‐narrow emission bandwidth (FWHM ~ 10 nm) has been developed. Using this LED backlight for a conventional TFT LCD, we can achieve 97.8% Rec. 2020 in CIE 1976 color space. The new LED has tuneable emission characteristics, recycles light for improved power efficiency, and leverages existing LED and phosphor manufacturing processes for lower cost, and long lifetime. Widespread application in other displays, and lighting are foreseeable.

Optical fine-tuning for improving the dark level of a reflective liquid crystal display.

Optical fine-tuning was performed to reduce blue light leakage in a conventional reflective LCD and to obtain a reflective LCD with a better contrast ratio. Total light leakage in the dark state was examined by simulation, according to the optical axes of the half-wave plate and LC layer and the central wavelength used in the optical design of the LCD. The contrast ratio of the reflective LCD could be improved by more than fivefold, compared to that of a conventional LCD with a wide-band optical design, when the optical axis angles of the half-wave plate and the LC layer were 75° and 15.68°, respectively, and the central wavelength was 520 nm. Therefore, such optical fine-tuning can be applied to reflective LCDs to increase their contrast ratio.

A novel stimulation method for multi-class SSVEP-BCI using intermodulation frequencies

Objective. Steady-state visual evoked potential (SSVEP)-based brain–computer interface (BCI) has been widely investigated because of its easy system configuration, high information transfer rate (ITR) and little user training. However, due to the limitations of brain responses and the refresh rate of a monitor, the available stimulation frequencies for practical BCI application are generally restricted. Approach. This study introduced a novel stimulation method using intermodulation frequencies for SSVEP-BCIs that had targets flickering at the same frequency but with different additional modulation frequencies. The additional modulation frequencies were generated on the basis of choosing desired flickering frequencies. The conventional frame-based ‘on/off’ stimulation method was used to realize the desired flickering frequencies. All visual stimulation was present on a conventional LCD screen. A 9-target SSVEP-BCI based on intermodulation frequencies was implemented for performance evaluation. To optimize the stimulation design, three approaches (C: chromatic; L: luminance; CL: chromatic and luminance) were evaluated by online testing and offline analysis. Main results. SSVEP-BCIs with different paradigms (C, L, and CL) enabled us not only to encode more targets, but also to reliably evoke intermodulation frequencies. The online accuracies for the three paradigms were 91.67% (C), 93.98% (L), and 96.41% (CL). The CL condition achieved the highest classification performance. Significance. These results demonstrated the efficacy of three approaches (C, L, and CL) for eliciting intermodulation frequencies for multi-class SSVEP-BCIs. The combination of chromatic and luminance characteristics of the visual stimuli is the most efficient way for the intermodulation frequency coding method.

59-1:Invited Paper: Modeling and Suppressing of Color Breakup

Field-sequential color displays are used as an alternative to the standard displays where energy consumption can be reduced or peak luminance can be increased. Its spatial resolution is potentially three times higher compared to a conventional color filter LCD. The concept of field sequential color displays shows the problem of color breakup artifact. This paper reviews the cause and the factors for the perception of color breakup, discusses the approaches for the reduction of color breakup. It is suggested that, with field-sequential color algorithm, 180Hz or 240Hz LC panel could have potential market in the high luminance and high resolution display applications.

P-144: A Transparent LCD with Improved Transmittance and Visibility

The pixel design of a transparent LCD is an important factor in obtaining high transmittance and visibility. In order to improve the performance of a transparent LCD, we adopted the WRGB sub-pixel structure and the optimized pixel-vcom electrode configuration. We successfully realized a 47 inches Full HD transparent LCD with 72% color gamut, achieving 17% in transmittance which was increased by 209% compared to the conventional LCD.

73-3: Super Multi-View 3D Display with Reduced Accommodation-Vergence Conflict using the Holographic Method

Novel 3D display architecture and algorithm are proposed and demonstrated Full HD 3D image with reduced accommodation-vergence conflict using limited computing power and a conventional LCD panel. The proposed 3D display architecture is integrated with a commercial 5.5” Full HD LCD panel and the used algorithm needs remarkably lower computing power than a conventional CGH algorithm based on Fresnel transformation. The experimental results show the accommodation depth cue which provides a clear 3D image only on focus position.

A high-ITR SSVEP-based BCI speller

Spelling is an important application of brain-computer interfaces (BCIs). Previous BCI spellers were not suited for widespread use due to their low information transfer rate (ITR). In this study, we constructed a high-ITR BCI speller based on the steady-state visual evoked potential (SSVEP). A 45-target BCI speller was implemented with a frequency resolution of 0.2 Hz. A sampled sinusoidal stimulation method was used to present visual stimuli on a conventional LCD screen. The online results revealed that the proposed BCI speller had a good performance, reaching a high average accuracy (84.1% for 2 s stimulation time; 90.2% for 3 s stimulation time) and the corresponding high ITR (105 bits/min for 2 s stimulation time, 82 bits/min for 3 s stimulation time) during the low-frequency stimuli, while 88.7% and 61 bits/min were achieved for a 4 s time window during the high-frequency stimuli.