Color Sequential Display Research Articles

2.2: Invited Paper: Towards Picture‐Level Color Breakup Assessment for Sequential Color Displays

Considering color breakup assessment is important to sequential color displays, we review a series of work by classifying into threshold display configurations, metrics for special patterns, and picture‐level metrics. Next, we propose a general picture‐level metric by modeling the color‐breakup‐related visual attention with a new theorem of dominant visual saliency.

Vertically aligned ferroelectric liquid crystals with high Kerr constant for field sequential color displays

In this article, we disclose a field sequential color display based on the vertically aligned deformed helix ferroelectric liquid crystals (VADHFLCs) with enhanced Kerr constant (KKerr). The KKerr for VADHFLCs strongly depends on the pitch (p0) and spontaneous polarization (Ps) of the ferroelectric liquid crystal (FLC) material. The longer pitch results in higher KKerr, but simultaneously provides a poor dark state and slower optical switching, therefore, a tradeoff exists here. A new FLC material has been developed to serve the device requirements. The KKerr of 104 nm/V2 has been achieved that provides response time ~300 μs at the electric field of 1 V/μm. Thereafter, the developed VADHFLC is deployed to a field sequential color display with a driving frame frequency~300 Hz.

A Review of Color Breakup Assessment for Field Sequential Color Display

AbstractAssessing color breakup is a prevalent and intrinsic issue in field sequential color displays. Here, the authors review selected works on the topic, including studies on threshold display configurations for perceptible color breakup, metrics for special patterns, and metrics for natural images with varying contents.

Simulation of color breakup based on measured display temporal responses

AbstractBased on the measured temporal luminance behavior of each field, the perceived color breakup (CBU) artifact for moving block on a field sequential color display is simulated and predicted. The prediction accuracy is evaluated by a perceptual experiment on a 240 Hz liquid crystal display. The results show a perfect matching between the simulation and the subjects' actual visual experience. The simulation also works well when motion compensation is applied. It is validated by another perceptual experiment that a perfect or a near‐perfect compensation degree can suppress CBU significantly in field sequential color system. CBU of nature image was also simulated and reproduced for both stable and pulse backlight by using this model, which could be rather valuable for the further development of CBU metrics.

4-8 フィールド・シーケンシャル・カラー表示における色割れと観視者視力および色表示周波数の関係

4-8 フィールド・シーケンシャル・カラー表示における色割れと観視者視力および色表示周波数の関係

Submillisecond-response nematic liquid crystals for augmented reality displays

We report a new nematic liquid crystal (LC) mixture with an ultra-low rotational viscosity (γ1 = 53.4 mPas @ 35°C), relatively high birefringence (Δn ≈0.15), and moderate dielectric anisotropy (Δe = −2.80 @ 35°C). When employed in a liquid-crystal-on-silicon (LCoS) projector with RGB light-emitting diodes (LEDs), a sub-millisecond response time is obtained without the need for complicated overdrive circuitry. Such a fast response time enables field sequential color display, which not only triples the optical efficiency and resolution density, but also greatly suppresses the image blur and color breakup. Moreover, the required cell gap is 1.2 µm, which is still manageable for high-yield manufacturing. We believe this mixture would find widespread applications for the emerging augmented reality displays.

P‐97: An Ultra‐low Voltage Blue Phase LCD for Mobile Applications

We report an ultra‐low voltage (<5V) two‐domain blue phase liquid crystal display (BPLCD) for mobile applications. Compared to fringe field switching, our BPLCD shows superior performance in response time, integrated transmittance, viewing angle, and color shift. It also enables color sequential display with tripled optical efficiency and resolution density.

P‐123: Distinguished Poster: Field Sequential Color Displays based on Reflective Electrically Suppressed Helix Ferroelectric Liquid Crystal

In this paper, we demonstrate a field sequential color display based on reflective electrically suppressed helix ferroelectric liquid crystal. The ultrafast response time enables this display cell to be driven at higher frequency with lower electric field. This reflective display cell can be used in projection displays and micro displays.

Enhanced performance configuration for fast-switching deformed helix ferroelectric liquid crystal continuous tunable Lyot filter.

In this paper, we present a novel design configuration of double DHFLC wave plate continuous tunable Lyot filter, which exhibits a rapid response time of 185 μs, while the high-contrast ratio between the passband and stop band is maintained throughout a wide tunable range. A DHFLC tunable filter with a high-contrast ratio is attractive for realizing high-speed optical processing devices, such as multispectral and hyperspectral imaging systems, real-time remote sensing, field sequential color display, and wavelength demultiplexing in the metro network. In this work, an experimental prototype for a single-stage DHFLC Lyot filter of this design has been fabricated using photoalignment technology. We have demonstrated that the filter has a continuous tunable range of 30 nm for a blue wavelength, 45 nm for a green wavelength, and more than 50 nm for a red wavelength when the applied voltage gradually increases from 0 to 8 V. Within this tunable range, the contrast ratio of the proposed double wave plate configuration is maintained above 20 with small deviation in the transmittance level. Simulation and experimental results showed the proposed double DHFLC wave plate configuration enhances the contrast ratio of the tunable filter and, thus, increases the tunable range of the filter when compared with the Lyot filter using a single DHFLC wave plate. Moreover, we have proposed a polarization insensitive configuration for which the efficiency of the existing prototype can theoretically be doubled by the use of polarization beam splitters.

P.83: ESHFLC Field‐Sequential Color Displays

AbstractHere we disclose the novel Electrically Suppressed Helix Ferroelectric (ESHFLC) field sequential color display based on photo‐aligned fast ferroelectric LCD. The ESH mode is characterized by high contrast. The frame frequency of 240 Hz has been demonstrated for the Field Sequential Color (FSC). Thus proposed display is characterized by the high contrast (10000:1), wide viewing angle, large color triangle (130% of NTSC) and low power consumption.

Fast response liquid crystal mode

A novel fast nematic liquid crystal mode is proposed. It relies on the fast relaxation flow from bend state to the twisted state in the optically compensated bend mode. Such new liquid crystal mode is indeed an improved mode from the optically compensated bend mode as it does not require any holding voltage. The new liquid crystal mode has fast response time and high contrast. The proposed fast liquid crystal mode is a good candidate for applications, such as optical shutter, field sequential color display, and 3D display.

A Color LED Driver Implemented by the Active Clamp Forward Converter

Because light emitting diodes (LEDs) have the advantages of dc working voltage, high luminescent efficiency, shortignition time, high reliability and pollution free, they have substituted for incandescent bulbs and fluorescent lampsgradually. In order to simplify circuit complexity, an active clamp forward converter with the sequential color display(SCD) control is proposed to drive red, green and blue (RGB) LED arrays. The proposed converter has zero-voltageswitching (ZVS) operations of both the main switch and the auxiliary switch, resulting in high system efficiency. DrivingRGB LED arrays sequentially by one converter can save components and reduce cost significantly. Additionally, thepulse-width modulation (PWM) control is applied to achieve a large chromaticity variation. The circuit operations areanalyzed in detail and the circuit parameters are designed based on the practical considerations. Finally, an illustrativeexample is implemented to demonstrate the feasibility and validity of the proposed LED driver.

Analysis and Design of the Active Clamp Forward Converter as a Color LED Driver

Light emitting diodes (LEDs) have substituted for incandescent bulbs and fluorescent lamps gradually in the residential, industrial and commercial lighting applications. This paper proposes an active clamp forward converter with the sequential color display (SCD) control to drive red, green and blue (RGB) LED arrays. Both of the main switch and the auxiliary switch can turn on under zero voltage switching (ZVS), resulting in high system efficiency. RGB LED arrays are sequentially driven by the same converter, which can save components and reduce cost significantly. Besides, the pulse-width modulation (PWM) control is applied to achieve a large chromaticity variation. The operation principles of the proposed LED driver are addressed. Experimental results of a 100W laboratory prototype are used to verify the feasibility and validity of the theoretical predictions.

A Survey of Low-power Techniques for Liquid Crystal Display Systems with Light Emitting Diode Backlight Units

As the technology evolves, end-users are stuffed with many kinds of handheld devices along with an enor-mous number of interactive multimedia applications and communication functionalities. These devices con-sume much power, especially for displaying their services or functions. In contrast, the battery, which is the main power supplier for such devices, has a much lower capacity growth compared to the power demands. This gap has inspired many researchers to study low-power display techniques. In the mean time, there came the invention of a light emitting diode (LED) as a new backlight source for a display panel. LEDs have been adopted in the most widely used Liquid Crystal Display (LCD) system. This paper focuses on recent noticeable low-power display techniques based on LCD systems, especially associated with an LED back-light unit as its light source. We categorize these techniques into four groups: 1) low-power techniques with backlight dimming, 2) low-power techniques with dynamic voltage scaling, 3) software-based low-power techniques, and 4) hardware-based low-power techniques, and review the core of each technique briefly. Among many techniques, concurrent brightness and contrast scaling technique in a color sequential LED-backlit display system achieved the largest power saving ratio by up to 90% of the total system power with a small distortion level. As future research, it is one of important methods to combine the pros from each beneficial technique into one synergistically in the aspect of the whole system power.

7.3: A Window LCD Achieved by Color‐Sequential Methods

AbstractIn this paper, a window LCD has been developed by using a color sequential panel. High transparency and well color saturation of a color sequential display were helpful for such applications. Relative information can be clearly displayed on the front panel of a demo‐box with products or exhibits inside.

20.1: A Method for Color BreakUp Suppression in a Color Sequential Display

AbstractThe Color Sequential Display CSD has the obviously shortcoming — color breakup CBU issues. An algorithm based on the CBU‐Suppression Method was proposed in this paper, which use light sensor, operation unit and time‐sharing detection to gain the red, green and blue intensity, respectively. Therefore, an equation to do the color compensation and white balance compensation can be proved.

P‐205L: Late‐News Poster: A Novel Pixel Circuit for Field Sequential Color LCD

AbstractA new pixel circuit with pixel memory is proposed for field sequential color display. The new pixel circuit associated with its unique driving scheme can solve voltage residue problem.

24.4: Subjective and Objective Assessments of Color Break‐Up on Field Sequential Color Display Devices

AbstractWe conducted both subjective and objective experiments for measuring color break‐up perception with the factors of stimuli size and sub‐frame frequency on the simplest field sequential driving. Our results indicate how to design the universal evaluation method for color break‐up issue on field sequential color display devices.

43.3: RGB LED Backlight of Color Sequential Display with Precise Current‐Balance Control Technique

AbstractThis paper proposes a high efficiency and precise current balance circuit in parallel RGB Light Emitting Diodes (LED) channels for color filter‐less panel display. The new technique not only enhances the current matching in each channel but also reduces the requirement of device numbers and external resistors. The error percentage of all channel LED currents can kept within 0.1% when the channel voltage has a voltage variation (Δ VCH) around 1. 1V. Furthermore, the proposed load dependent minimum drain voltage can effectively reduce the voltage drop across the precise current balance circuit. As a result, the efficiency of the LED driver can be improved.

38.2: A Novel Design for Internal Touch Display

AbstractChunghwa Picture Tubes LTD has developed an innovative design of touch panel embedded in LCD which includes a capacitive type touch panel and integrates Color Sequence Display (CSD). Compared with the former design, the new design employs dual side coating structure, the X and Y sensor traces are coated on single layer and it provides higher transparency, lower interference, higher yield and improved touch sensitivity. Furthermore, the new structure is also coated thin films on single side for External Touch Panel. It can be produced flexibly depends on customers' demand. In additional, we have integrated with Color Sequential Display to provide the wider color gamut and higher transparency.