BiNem® manufacturing process for mass production

Abstract— As the need for high‐resolution ultra‐low‐power bistable displays grows, it is important to rapidly implement the mass‐production manufacturing of BiNem® LCDs. The cost‐effective approach for BiNem® manufacturing is based on using STN manufacturing process technologies since BiNem® and STN displays have a similar internal structure. The key differences between BiNem® and STN displays from a manufacturing point of view will be discussed. We show that industrial STN manufacturing equipment can be used to produce BiNem® LCDs at competitive costs. Reflective e‐book display modules with VGA resolution are produced in the pilot‐production series.     

Reflective bistable nematic displays (BiNem®) fabricated by standard manufacturing equipment

Abstract— Bistable liquid‐crystal displays have been developed by using BiNem® technology. In this paper, the BiNem® principle, addressing, power consumption, reflective mode, and manufacturing process will be described, and performance of the latest displays will be discussed. We will show that this technology has simultaneously low power consumption due to bistability, very good visual quality, passive‐addressing mode, and a manufacturing process compatible with STN mass‐production equipment.     

Optical design and roll‐to‐roll fabrication process of microstructure film for wide viewing LCDs

We have developed a new microstructure film for wide viewing liquid crystal displays (LCDs). By attaching it to the surface of a conventional LCD, the viewing angle characteristics of LCD has drastically improved without causing a blur of the frontal image and a decrease in the contrast ratio under bright ambient light conditions. This film can be applied to various LC modes including twisted nematic and multidomain vertical alignment by changing its internal micrometer‐size 3D structure. Further, this film can be mass‐produced efficiently by self alignment roll‐to‐roll process.     

Gray scale in zenithal bistable LCDs: The route to ultra‐low‐power color displays

Abstract— Zenithal bistable devices (ZBD?) exhibit rugged image storage, excellent optical performance, fast latching, and infinite multiplexibility. The excellent performance characteristics are achieved using a surface‐relief grating to align the nernatic liquid crystal. Such gratings offer a high degree of design flexibility, at manufacturing costs equivalent to today's STN displays. In the present work, the grating shape is varied within each pixel to produce several separate latching thresholds, thereby introducing error‐free analog gray scales. Passive‐matrix waveforms, suitable for use with commercial STN drivers, are reported and shown to discriminate between at least seven error‐free grays in a test cell. The combination of analog and digital grays was considered. Careful selection of the digital dither weighting factors allows for a large total number of grays to be achieved, while reducing the effect of errors if all of the analog levels are not achieved.     

An overview of product issues in wide‐viewing TFT‐LCDs

Abstract— Several TFT‐LCD devices exhibiting high image quality have been developed and commercialized, overcoming the narrow viewing‐angle characteristics of conventional twisted‐nematic (TN) devices. Nevertheless, no single device dominates large‐sized TFT‐LCDs. In this paper, the product issues of existing LC devices related to manufacturing process and performance are discussed.     

A new pixel design and a novel driving scheme for multi‐domain vertically aligned LCDs

Abstract— By using a new pixel design and a novel driving scheme that adds a bias electrode and a bias TFT to the ordinary pixel structure, a high‐contrast‐ratio and wide‐viewing‐angle LCD mode, refered to as the biased vertical‐alignment (BVA) mode, has been sucessfully developed. Compared to the published data on the PVA and MVA modes, the BVA mode has a distinct advantage of lower manufacturing cost due to the elimination of a lithographic process step that forms either ITO cuts or protrusions on the color‐filter substrates. The BVA mode requires ITO cuts on the TFT substrate similar to that for the PVA and MVA modes. The 15‐in. BVA‐mode XGA prototype exhibits a high contrast ratio of 1200:1 and high cell transmittance of 4.3%.     

High‐speed nonchiral‐smectic‐C liquid‐crystal modes for display applications

Abstract— Three nonchiral‐smectic‐C (NSC) liquid‐crystal (LC) modes having fast‐response and wide‐viewing characteristics applicable for next‐generation LCDs are described. In the NSC LC modes, fast analog optical modulation is achieved by means of a coupling with an external electric field in a dielectrically driving scheme. The fast response results intrinsically from no interlayer interferences during molecular rotation in the layered structure of the NSC LC. Moreover, the self‐formation of two domains and the in‐plane variations of the optic axis produce the wide‐viewing properties. A step‐wise temperature annealing process is employed for a stable and well‐aligned smectic layer structure in a time‐efficient manner.     

Viewing‐angle compensation of TN‐ and ECB‐LCD modes by using a rod‐like liquid‐crystalline polymer film

Abstract— A liquid‐crystal line retardation‐film technology by using a rod‐like liquid‐crystalline polymer (LCP) for various LCD modes have been developed. In particular, considerable improvements in viewing‐angle performance have been achieved for the twisted‐nematic (TN) and the transmissive/transflective electrically controlled birefringence (ECB) modes by using hybrid aligned nematic film (NH Film).     

Novel photo‐aligned LC‐polymer compensation film for wide‐view TN displays

Abstract— We demonstrate a novel TN‐display compensation film with excellent contrast and minimal color shift, meeting the requirements for avionics displays. The film configuration was identified via extensive computer modeling. The experimental implementation based on ROLIC's LPP/LCP (linearly photopolymerizable polymer/liquid‐crystal polymer) technology results in excellent agreement with theoretical predictions.     

A 400‐dpi reflective storage ferroelectric liquid‐crystal display for highly readable,low‐power mobile display applications

Mobile products require longer battery lifetimes and increased information content from the display. A ferroelectric liquid‐crystal reflective storage mode was demonstrated. This display only needs updating when the image changes, resulting in ultra‐low power consumption. Passive‐matrix addressing allows for high‐resolution text to be displayed.     

A fast‐switching OCB‐mode LCD for high‐quality display applications

Abstract— Optically compensated bend (OCB) mode is a promising technology, due to its wide range of viewing angles without gray‐scale inversion or color shift, fast response, high contrast ratio, and wide temperature range. This paper summarizes the fundamental characteristics of OCB mode and discusses the development of field‐sequential‐color displays and 3‐D displays for future high‐quality display applications.     

The design of radio frequency energy harvesting and radio frequency‐based wireless power transfer system for battery‐less self‐sustaining applications

In this paper, the RF energy harvesting system and RF‐based wireless power transfer system are proposed and designed for battery‐less self‐sustaining application. For energy harvesting, the designed antenna array improves the received RF power effectively and also can harvest RF energy in multi‐frequency bands. For wireless power transfer, the proposed helical antenna realizes the system design in miniaturization. Subsequently, the T shape LC matching network are designed between the antenna and the rectifying circuit to obtain more power transmission. The measured results show that the proposed Wi‐Fi rectifier and 433 MHz rectifier offer a maximum conversion efficiency of 66.8% and 76% in case of the input power is ?3 dBm and 0 dBm, respectively. Finally, the performance of the RF‐based wireless power transfer system and RF energy harvesting system are attested by experimentally measurement, the measured results indicate that these systems can be used to power electronic.     

Analytical calculation for input impedance of a circularly‐polarized ferrite disk antenna including higher order modes

We propose an accurate analytical model for a circularly polarized antenna comprising a normally magnetized, grounded ferrite disk with a metalized top surface. The antenna is assumed to be excited by a conventional current probe. In the case of a thin ferrite disk, the electromagnetic fields of the dominant mode of the antenna do not vary in the direction normal to the disk. However, with increasing thickness of the ferrite disk, higher order modes start to affect antenna characteristics such as resonance frequency. This work presents an analysis of the structure that takes into account all higher modes of the antenna. To validate the theoretical calculations, HFSS simulations are performed. The antenna can be tuned by changing the magnetic bias field.     

A novel pixel memory using integrated voltage‐loss‐compensation (VLC) circuit for ultra‐low‐power TFT‐LCDs

Abstract— A novel pixel memory using an integrated voltage‐loss‐compensation (VLC) circuit has been proposed for ultra‐low‐power TFT‐LCDs, which can increase the number of gray‐scale levels for a single subpixel using an analog voltage gray‐scale technique. The new pixel with a VLC circuit is integrated under a small reflective electrode in a high‐transmissive aperture‐ratio (39%) 3.17‐in. HVGA transflective panel by using a standard low‐temperature‐polysilicon process based on 1.5‐μm rules. No additional process steps are required. The VLC circuit in each pixel enables simultaneous refresh with a very small change in voltage, resulting in a two‐orders‐of‐magnitude reduction in circuit power for a 64‐color image display. The advanced transflective TFT‐LCD using the newly proposed pixel can display high‐quality multi‐color images anytime and anywhere, due to its low power consumption and good outdoor readability.     

High‐luminance 1.8‐mm‐pixel‐pitch CNT‐FED for ubiquitous color character displays

Abstract— A high‐luminance 1.8‐mm‐pixel‐pitch CNT‐FED for color character displays has been developed. The display panel has 32 × 256 color pixels, and the subpixel size is 0.6 × 1.8 mm. The display panel can provide good visibility when installed even in outdoor locations. The power consumption is low enough for the display to be battery driven. The practical application is the display of important messages regarding the evacuation from disaster areas, even under emergent no‐power conditions similar to the messages on vending machines.     

Design and analysis of wideband eight‐way SIW power splitter for mm‐wave applications

High‐performance, wideband three‐stage power splitters based on substrate integrated waveguide (SIW) are presented. Broadband‐tapered microstrip transitions are used for feeding the SIW structures, which provide 7.5 GHz bandwidth from 21.5 to 29 GHz with return loss below ?20 dB. In addition, various T junctions are tuned, not only to provide broadband performance up to mm‐wave frequencies but also offer low‐phase and amplitude imbalance when cascaded in multistage 1 × 8 splitters. 1 × 4 and 1 × 2‐T junctions are adjusted through parametric analysis to provide wide bandwidth of 3.5 GHz at 24.5 GHz and ?15 dB reflection coefficient. The optimal microstrip transitions and T junctions are used to design a broadband, eight‐way power splitter with 15 dB return loss from 23.0 to 26.4 GHz and phase and amplitude imbalance of ±2.5° and ±0.8° dB, respectively. Furthermore, optimum positions of all inductive posts in terms of guided wavelength are also provided for assisting the direct design of mm‐wave, high‐performance power splitters.     

Design of a subarray with special radiation pattern for low profile wide‐angle scanning phased array

A low profile subarray with a special radiation pattern for the wide‐angle H‐plane scanning phased array is presented. Five parallel dipoles located above a metal ground serve as the radiator. The differential evolution (DE) algorithm is used to obtain the weights for a special radiation pattern, which is realized by a corresponding feed network. The overall dimension of the proposed subarray is only 0.55λ₀ × 0.55λ₀ × 0.14λ₀. The prototype is fabricated and measured, and the measurement results are consistent with the simulation results. Because of the special radiation pattern and compact size, this subarray is suitable as an element in the wide‐angle scanning phased array. A uniform linear array consisting of five proposed subarrays is built in high frequency structural simulator, and the simulated results show that the main beam can scan nearly from ?70° to +70° in the H‐plane with a gain fluctuation less than 3 dB.     

Class G approach for low‐voltage,high‐efficiency PA design

Class G power amplifier (PA) design guidelines are presented and experimentally validated, showing the interesting features of the new approach. For the same operating conditions, the Class G amplifier exhibits superior performances if compared to a tuned load one in large signal gain, output power, and third‐order intermodulation (IM3), with a power‐added efficiency (PAE) improvement of 38.5%. © 2000 John Wiley & Sons, Inc. Int J RF and Microwave CAE 10: 366–378, 2000.     

Practical CNT‐FED structure for high‐luminance character displays

Abstract— A high‐luminance CNT‐FED character display using a simple line rib structure was constructed. The display panel had 48 × 480 dots and the subpixel pitch was 1 mm. The greatest benefit of a display using CNT technology is high luminance performance with low‐power consumption. The luminance of the green‐color dot wasca. 10,000 cd/m² under 1/1 6 duty‐cycle driving at a 6‐kV anode voltage. The high luminance of the display panel can provide good visibility when installed even in outdoor locations, and the power consumption was ca. 4 W at the character displaying module. This, a CNT‐FED for character displays also has potential multifunctionality, which could be battery driven. It should be useful for public displays even under emergency no‐power conditions. In this work, a practical structure and process technologies for making ribs with reasonable cost were developed. The newly introduced 2‐mm‐tall line ribs as spacers were formed by using innovative production processes; i.e., the rib paste was pushed out of a multi‐slit nozzle, and the rib shape was formed by UV‐light irradiation. The developed panel structure and manufacturing processes also had the advantages of size flexibility and high production yield.     

A design method for flicker‐free liquid crystal display panels based on indium‐gallium‐zinc‐oxide thin‐film transistors

This paper proposes a design method to reduce the flicker of liquid crystal display panels based on indium‐gallium‐zinc‐oxide (IGZO) thin‐film transistors (TFTs). The proposed design method employs a human factor model to convert the flicker measured at low frame frequency (F _FRAME) to a modification value of the measured flicker (MVMF ) having a frequency sensitivity of flicker, which can distinguish between no blinking and weak blinking. To investigate the causes and characteristics of flicker, the frequency component and increase factor of flicker are analyzed using the checkerboard and solid images. The increase factor in flicker is examined using IGZO TFTs with different antenna ratios (AR s) that cause the variation in threshold voltage of IGZO TFT. To verify the proposed design method, two test panels are implemented with asymmetric and symmetric AR s. The MVMF s of the 15 Hz component at a low F _FRAME of 30 Hz show that the solid image with a symmetric AR has an MVMF of ?62.9 dB, which is improved by 24.3 dB compared to that with an asymmetric AR . Therefore, the proposed method is applicable for a flicker‐free liquid crystal display panels at a low F _FRAME.