Driving Liquid Crystal Research Articles

A flexible optically driven liquid crystal display based on RM257 doping

With advances in technology, requirements for the performance of liquid crystal displays (LCDs) are gradually increasing, especially for flexible displays, which involve many new challenges. Here, we propose a new method for implementing optically driven LCD flexible displays. Upon doping an E7 nematic liquid crystal (LC) with RM257 liquid crystal monomer and polymerizing it using ultraviolet light, a polymer network forms as the spacer between the two substrates of the LC, maintaining the surrounding E7 LC in a relatively stable state and improving the mechanical properties of the LC. This also endows the LC mixture with a limited capacity for deformation recovery and enables uniform deformation under stress, thereby achieving flexible displays. Applying an electric field to the two ends of the LC cell, the viscosity coefficient of the LC molecules is improved and the rewriting time can be optimized. This type of LC cell can be programmed through light control, achieving low power consumption for a wearable display device.

Improvement of rewriting time of optically driven liquid crystal display by azo-dye doping

ABSTRACT Optically driving liquid crystal display (ODLCD) uses polarized light field to control the orientation of the liquid crystal, and the display content can be maintained without external electric field, with extremely low power consumption. However, it has a long rewriting time, which is difficult to achieve industrialization. In order to improve the rewriting performance, the influence of the rotational viscosity of the mixed system of azo-dyes (SD1, MR) and nematic liquid crystal (5CB) on the rewriting speed is investigated. The experimental results show that the electro-optical properties of SD1-5CB and MR-5CB have great changes after irradiation by polarized light, among which the SD1-5CB is the best to improve the performance. With the increase of SD1 concentration, the rotational viscosity of SD1-5CB decreases significantly due to the change of cis-trans isomerization of azo-dye, and the optimal doping concentration is 0.5 wt%. In this case, the rewriting time is shortened from 45 s to 11 s, which has the potential to broaden the application of ODLCD.

Impact of silver nanowires on the writing time of optically driven liquid crystal displays

Impact of silver nanowires on the writing time of optically driven liquid crystal displays

Effect of nickel oxide doping on the optically driving liquid crystal display

Effect of nickel oxide doping on the optically driving liquid crystal display

P‐12.12: Increasing the Rewriting Speed of Optically Driving Liquid Crystal Display by RM257Doping

The optically driving liquid crystal display (ODLCD) can realize the display function by changing the alignment direction of liquid crystal molecules inside by exposing to the polarized blue light, which has the advantages of low power consumption, non‐contact alignment, easy to fabricate. However, a big issue arises in response time, i.e., rewriting time of the ODLCD. The rewriting time for the ODLCD depending on doping with RM257 was studied. RM257was cured perpendicular to the substrates by applying voltage across the sample that forming a net‐like structure inside liquid crystal 5CB.Among the 9 different RM257 concentrations, 5% RM257 in the mixturewasfound to be the optimal and the minimum rewriting time of 4s had been reached.

P‐12.2: Increasing the Response time of the Optically Driving Liquid Crystal Display by SiO 2 Nano‐particle Doping

In the past few years, people have put forward higher and higher requirements for the performance of liquid crystal displays, such as higher refresh rate and picture continuity which requires liquid crystal displays having lower threshold voltage and shorter response time. In order to study the electro-optical properties of liquid crystal display, the experiments was designed to dope SiO2 nano-particles into the SD1 solution and to observe the impact on the threshold voltage, the electrical response time and the rewriting time of the optically driving liquid crystal display (ODLCD). The experiment results show that doping SiO2 nano-particles in the liquid crystals can reduce the threshold voltage, the electrical response time and the rewriting time of ODLCD.

A Mesoporous Silica Nanoparticle-Doped Photo-Alignment Layer and Liquid Crystal Layer for Optimizing the Rewriting Speed and the Response Time of Optically Driving Liquid Crystal Displays

Optically driving liquid crystal displays (ODLCDs) are widely applied in display and optical devices due to their long axis of liquid crystal (LC) molecules that can be tuned by a photo-alignment layer under exposure polarized light. However, their use remains challenging due to their long rewriting time and response time. In this work, the rewriting time and the response time of an ODLCD depending on mesoporous silica nanoparticles (MSNs) doped in azo-dye (SD1) and LC 5CB were studied. Among the different concentration ratios of SD1-MSNs (1-0 to 1-0.1), a ratio of 1-0.07 was optimal, decreasing the rewriting time by 40 s (from 69.1 to 29.6 s). Meanwhile, the response time was improved 10 times with MSNs doped into 5CB.

Electrically driven liquid crystal network actuators.

Soft actuators based on liquid crystal networks (LCNs) have aroused great scientific interest for use as stimuli-controlled shape-changing and moving components for robotic devices due to their fast, large, programmable and solvent-free actuation responses. Recently, various LCN actuators have been implemented in soft robotics using stimulus sources such as heat, light, humidity and chemical reactions. Among them, electrically driven LCN actuators allow easy modulation and programming of the input electrical signals (amplitude, phase, and frequency) as well as stimulation throughout the volume, rendering them promising actuators for practical applications. Herein, the progress of electrically driven LCN actuators regarding their construction, actuation mechanisms, actuation performance, actuation programmability and the design strategies for intelligent systems is elucidated. We also discuss new robotic functions and advanced actuation control. Finally, an outlook is provided, highlighting the research challenges faced with this type of actuator.

P‐12.13: Increasing the Rewriting Speed of Optically Driving Liquid Crystal Display by NiO Doping

The optically driving liquid crystal display (ODLCD) realizes display function by controlling the alignment directions of liquid crystals (LC) under exposure light, which has applications in optical devices. However, it is still limited to the laboratory for its long rewriting time of the ODLCD. The rewriting time for the ODLCD depending on SD1 with Nickel oxide (NiO) doping was studied. The SD1‐NiO distribution was discussed by SEM images. Among the 10 different ratios of SD1‐NiO concentration, the ratio of 1−0.08 is optimal and a minimum rewriting time of 6s has been reached.

A 0.37‐in. 5900PPI liquid crystal on silicon CMOS SoC using low voltage high dynamic voltage range novel pixel circuit for augmented reality micro‐displays

AbstractA new pixel circuit and a driving circuit are proposed for high‐resolution field sequential color driven liquid crystal on silicon (LCoS) micro‐displays. The proposed pixel circuit is based on data storage with global charge transfer, whose reference node is controlled to increase the LC node voltage and to decrease the response time. Pixel LC reference node voltage modulation is adopted to reduce the pixel size and the driving circuit operation voltage by half. This allows the pixel display to be operated with an overdrive scheme, at low‐voltages and a wide dynamic range. As a result, the pixel driving circuits and the pixel circuit achieve low‐color crosstalk, and both power consumption and area are greatly reduced. To verify proper operation of the proposed pixel circuit, a 0.37‐in. 360‐Hz field refresh rate full‐HD video resolution 5900PPI 4.3‐μm pixel pitch backplane is implemented in 0.11‐μm CMOS technology using 1.5‐ and 6‐V supplies for logic and pixel driving, respectively. Measurement results demonstrate that the LC voltage dynamic range and the maximum brightness are increased by as much as 1.4 V and 39.7%, respectively. The response time is also reduced by approximately 30% owing to the proposed unique overdriving scheme.

The Effect of Operating Temperature on the Response Time of Optically Driven Liquid Crystal Displays

Optically driven liquid crystal displays (ODLCDs) realizes their display function by tuning the easy axis of liquid crystal (LC) molecules under polarized blue light, which has been utilized in some optical devices due to its advantages of ultra-low power consumption. However, a big issue arises in response time, i.e., the rewriting time of the ODLCD. The rewriting time of ODLCD samples was studied. Rotational viscosity plays a very important role for decreasing the rewriting time of the ODLCD. The operating temperature was changed from room temperature to nearly clearing point, the rewriting time decreased a lot as the rotational viscosity decreased for the five different kinds of the LCs. The rewriting time can be decreased from 5.2 s to 0.2 s around 25 times for the LC N4.

Colour generation for optically driving liquid crystal display

ABSTRACT The optically driving liquid crystal displays (ODLCDs), by changing the easy axis of liquid crystal molecules under exposure light, are exploited in many display devices requiring ultra-low consumption. In this manuscript, we propose foldable and bendable colour ODLCDs lacking electronics and common back light. Two techniques to realise colour ODLCDs are discussed using colour filter and reflective paint as colour array sector. With these two approaches, we are able to produce three-primary-colour (red, green and blue) display with 21% NTSC colour triangle. In addition, a high-resolution colour display can be achieved through improving resolution of colour array sector.

The effect of chiral dopant on the rewriting speed of optically driving liquid crystal display

ABSTRACTMixing liquid crystal with chiral dopant for increasing the response speed of optical driving liquid crystal display was investigated in this paper. It is demonstrated that by adding chiral dopant, rewriting time could be decreased from 30 s to 20 s with good repeatability. Without adding other steps in the process of making cells, this improvement is due to the stronger elastic energymaking LC molecules twist more easily.

P‐11.15: The Influence of chiral dopant on the Rewriting Speed of Optically Driving Liquid Crystal Display

For a liquid crystal display device, like optically driving liquid crystal display (ODLCD), the response time plays a crucial role. In this paper, a new method is proposed to increase the rewriting speed of ODLCD. With chiral dopant mixing with the liquid crystal 5CB, the rewriting time can be increased by 1.5 times.

Tunable nonpolarizing one-dimensional crossed resonant gratings incorporating electrically driving liquid crystal

A tunable nonpolarizing filter composed of one-dimensional crossed resonant gratings and an electrically driving liquid crystal (LC) cell is designed, fabricated and demonstrated. The filter is designed by using different grating periods to obtain nonpolarizing spectra for oblique incidence. The filter sample is fabricated through thin-film deposition, ultraviolet lithographic patterning, deep reactive ion etching and LC injection. Finally, the resonance spectra of the fabricated sample are measured by a spectrometer and the measured results are consistent with the theory. The experimental results show that the nonpolarizing resonance spectra can be tuned by electrically driving the LC cell of the proposed device.

Greyscale generation for optically driving liquid crystal display

ABSTRACTIt is very difficult to display greyscale for an optically driving liquid crystal display (ODLCD) because the driving unit and display unit are separate, and there are no electronics in the display part of ODLCD. In this paper, two greyscale generation methods are proposed to achieve this goal. Six and nine grey levels are separately achieved through the two methods.

A High-Efficiency Low-Power Chip-Based CMOS Liquid Crystal Driver for Tunable Electro-Optic Eyewear

A high-efficiency low-power chip-based liquid crystal (LC) driver has been successfully designed and implemented for adaptive electro-optic eyewear including tunable vision correction devices (eyeglass, contact lens, intraocular lens, occluder, and prism), phoropter, iris, head-mounted display, and 3D imaging. The driver can generate a 1 kHz bipolar square wave with magnitude tunable from 0 V to 15 V to change the lens focus adaptively. The LC driver output magnitude is controlled by a reference DC voltage that is manually tunable between 0 and 3 V. A multi-mode 1×/2×/3×/4×/5× charge pump is developed for DC-DC conversion to expand the output range with a fast-sink function implemented to regulate the charge pump output. In addition, a new four-phase H-bridge driving scheme is employed to improve the DC/AC inverter efficiency. The LC driver has been successfully implemented and tested as an IC chip (8.6 mm × 8.6 mm) using AMS 0.18 μm High-Voltage CMOS technology.

Tunable nonpolarizing guided-mode resonance filter incorporating electrically driving liquid crystal

A tunable nonpolarizing guided-mode resonance filter (GMRF) incorporating an electrically driving polymer-dispersed liquid crystal (PDLC) cell is designed, fabricated and demonstrated. By studying the dependence of the resonance wavelength on the grating period, the two-dimensional (2D) nonpolarizing GMRF is designed using different grating periods along the x and y axes at oblique incidence. The 2D electrically driving GMRF sample is fabricated through thin-film deposition, electron beam lithography and PDLC injection. Moreover, the resonance spectra of the fabricated sample are measured by a spectrometer and themeasuredresults areconsistentwiththetheory. Thus the nonpolarizing resonance spectra can be tuned by electrically driving the refractive index of PDLC cell inrealtime.

30-4: Low-voltage Driving Liquid Crystal Lens with Precise Control of Pretilt Angles using E-beam Lithography

30-4: Low-voltage Driving Liquid Crystal Lens with Precise Control of Pretilt Angles using E-beam Lithography

Coupled electric fields in photorefractive driven liquid crystal hybrid cells – theory and numerical simulation

AbstractIn cyclic articles previously published we described and analysed self-organized light fibres inside a liquid crystalline (LC) cell contained photosensitive polymer (PP) layer. Such asymmetric LC cell we call a hybrid LC cell. Light fibre arises along a laser beam path directed in plane of an LC cell. It means that a laser beam is parallel to photosensitive layer. We observed the asymmetric LC cell response on an external driving field polarization. Observation has been done for an AC field first. It is the reason we decided to carry out a detailed research for a DC driving field to obtain an LC cell response step by step. The properly prepared LC cell has been built with an isolating layer and garbage ions deletion. We proved by means of a physical model, as well as a numerical simulation that LC asymmetric response strongly depends on junction barriers between PP and LC layers. New parametric model for a junction barrier on PP/LC boundary has been proposed. Such model is very useful because of lack of proper conductivity and charge carriers of band structure data on LC material.