A Gray-Level Dependent Pre-Emphasis Column Driver With Fast Settling for Active-Matrix LCD Applications

When current domestic Active Matrix Liquid Crystal Display (AMLCD) sources became unavailable, prime contractors for military aircraft faced a severe problem with the sudden obsolescence of these assemblies. AMLCDs had become central to crew station design, but the only qualified North American source had failed. The problem was further complicated as several programs were beginning production, and supplies of existing, useable AMLCDs were rapidly being depleted. Solutions to the availability of AMLCDs had to be found quickly. The F/A - 18E/F program faced a unique situation in that three different displays, manufactured by two different suppliers, were affected by the loss of the AMLCD source. Both of the suppliers, for various technical and programmatic reasons, chose different approaches to the crisis. The advantages and disadvantages of each approach are examined in this paper. In addition, Boeing has formed a Displays Process Action Team (DPAT) to examine whether or not it is possible to use common displays across the Company's diverse product lines.

Chapter 5 - Performance Characteristics

The performance of advanced flat panel displays is intrinsically linked to critical properties of the substrate material. In the manufacture of active-matrix liquid crystal displays (AMLCDs) and some emissive displays, there are certain process steps that require extreme conditions such as strong chemical washes and temperatures in excess of 600°C. As a result, the glass substrate used in these displays must be able to withstand these environments without degradation of its properties. It has become apparent that the flat panel display (FPD) manufacturers will benefit from substrates with improved acid durability, higher temperature capability, and thermal expansion coefficients consistent with other display materials.This paper focuses on one of the less-understood features of the glass substrate: the expansion characteristics as a function of temperature. Thermal expansion is important as it affects the compatibility of the glass with display materials, which, in the case of AMLCDs and some silicon-microtip field emission displays (FED), require an expansion close to that of silicon. In addition, thermal breakage during processing is directly proportional to the expansion coefficient.This study focused on the thermal expansion characteristics of two different FPD substrate glasses. The first one is code 7059, manufactured by Corning Incorporated and currently the standard in AMLCDs. A new substrate composition, Corning code 1737, with enhanced durability, temperature capability, and expansion tuned to the AMLCD applications will also be discussed.

Time-dependent color simulation of active-matrix liquid crystal display adopting the field sequential driving method

This paper presents a new low-leakage gate driver circuit using hydrogenated amorphous silicon (a-Si:H) thin-film transistors (TFTs) for active-matrix liquid crystal display (AMLCD) applications. The pull-down TFTs are turned OFF to maintain the high driving capability of the proposed circuit. Four phase clock signals with a duty ratio of 33% are utilized to turn ON the pull-down TFTs in advance to improve the stability of the row line at ${V}_{L}$ . The electrical characteristics of a fabricated a-Si:H TFT are measured to establish the model for HSPICE simulation to elucidate the effect of charge loss on the proposed circuit. Measurements confirm that the output waveforms of the proposed gate driver circuit remain identical to the initial waveforms and can be stabilized at ${V}_{L}$ at 85 °C over 720 h, ensuring the feasibility of the use of the proposed gate driver circuit in AMLCDs.

Bit slice addressing (BSA) is useful to display grayscales in fast switchable bi-stable displays and active matrix liquid crystal displays (AMLCD). The display is used as a dynamic mask and intensity of light source that illuminates the display is controlled to be proportional to the bit-weight of the bit that was used to refresh the display. A viewing angle characteristic that is independent of grayscales, color purity of images, reduction of motion blur, wide voltage margin to switch the state of pixels, option to reduce power consumption of backlight and low hardware complexity of data drivers are some of the advantages of BSA. Multi-BSA is also proposed to drive the state-of-the-art active-matrix LCDs.

: This report discusses the results of a Honeywell Technology Center program focused on developing thermal management methodologies and flip-chip-on-glass (FCOG) driver bonding techniques which are key to ruggedizing automotive-grade commercial off-the-shelf (COTS) active matrix liquid crystal displays (AMLCD) for use in military applications like the F-16 high-performance fighter environment. Through extensive thermal modeling, several techniques were identified to facilitate heat flow away from the temperature-sensitive liquid crystal material, keeping the core temperature within acceptable operating limits (below +85 C) in worse case conditions (200 fL with +50C ambient and 883Watts/mA2 solar load in a closed cockpit) without the use of forced air cooling for display sizes up to 5x5-inch. Environmental testing on eight modified Sharp displays verified modeling results. The FCOG bonding has many mherent advantages over traditional tape automated bonding (TAB) techniques, one of which is 75% reduction in off-glass interconnect density, making them much less susceptible to vibration failure. Several FCOG bonding materials (e.g., anisotropic conductive films) have been explored and tested using various test vehicles and subjected to F-16 environmental conditions for temperature shock, temperature cycling, vibration, and humidity.

This paper presents the recent developments in our Active Matrix Liquid Crystal Displays for military, avionic and automotive applications. Data is presented for PIN diode driven active matrix liquid crystal display, with full color and high resolution (164 lines per inch). Optimization of color coordinates versus transmission has led us to better overall display performance. The contrast ratios were measured for various viewing angles (+/-60H and +45,-15 V) at different temperatures (-54 C to +85 C). The display shows good high ambient contrast ratio both by theoretical model and experimentally. The discrimination index model is used together with measurements to get the index for different high ambient light levels.

Abstract— An active matrix LCD with integrated drivers was developed using a standard amorphous silicon TFT technology. Despite the low mobility, the high threshold voltage and high parasitic capacitance of this technology compared to polysilicon technologies, we have built an high performance light valve for projection application. We shall discuss the topology and the main features of the integrated row and column drivers and the matrix.

Over the past several years, Active Matrix Liquid Crystal Displays (AMLCDs) have been touted as the ultimate flat panel display for use in the tactical cockpit environment because of their optical and environmental performance. The main drawback for AMLCDs has been the stable source of supply needed to continue aircraft production at a reasonable cost for upwards of 20 years. Rear projection displays have been discussed as a potential replacement for CRT and AMLCD based displays, providing comparable technical performance, scalable display surface sizes and Commercial Off The Shelf (COTS) parts usage. The F/A-18E/F program has been developing the projection based on Digital Enhanced Color Display (DECD) for integration into the cockpit as a multi-purpose color display, capable of providing both video and complex graphics formats. This paper will examine projection technologies and discuss some of the major technical challenges and accomplishments encountered during development and integration for aircraft cockpits. In addition, future integration of projection technology into large area displays, panoramic displays and Head-Up Displays (HUDs) will be discussed.

Active Matrix Liquid Crystal Displays (AMLCDs) have been developed for a number of portable electronic applications. New applications of AMLCDs such as workstations and desktop displays require larger diagonals and higher resolutions. The design limitations of the technology are reviewed.

Cathode ray tube (CRT) technology dominates the direct view display market. Mature CRT technology for many designs is still the preferred choice. CRT manufacturers have greatly improved the size and weight of the CRT displays. High performance CRTs continue to be in great demand, however, supply have to contend with the vanishing CRT vendor syndrome. Therefore, the vanishing CRT vendor syndrome fuels the search for an alternate display technology source. Within the past 10 years, field emission display (FED) technology had gained momentum and, at one time, was considered the most viable electronic display technology candidate [to replace the CRT]. The FED community had advocated and promised many advantages over active matrix liquid crystal displays (AMLCD), electro luminescent (EL) or Plasma displays. Some observers, including potential FED manufacturers and the Department of Defense, (especially the Defense Advanced Research Project Agency (DARPA)), consider the FED entry as having leapfrog potential. Despite major investments by US manufacturers as well as Asian manufacturers, reliability and manufacturing difficulties greatly slowed down the advancement of the technology. The FED manufacturing difficulties have caused many would-be FED manufacturing participants to abandon FED research. This paper will examine the trends, which are leading this nascent technology to its downfall. FED technology was once considered to have the potential to leapfrog over AMLCD's dominance in the display industry. At present the FED has suffered severe setbacks and there are very few [FED] manufacturers still pursuing research in the area. These companies have yet to deliver a display beyond the prototype stage.

ABSTRACTIn this paper, feasibility of crystalline silicon (c-Si) substrate for transmissive active matrix liquid crystal displays (AM-LCDs) has been investigated. The transparent pixel areas of AM-LCD were formed by vertical etching of (110) silicon substrate using anisotropie etching property of aqueous KOH. Combining this vertical etching process with the conventional MOSFET fabrication process, the pixel switching devices, peripheral circuits and transparent apertures were successfully integrated on the same c-Si substrate. The pixel NMOS devices exhibit an electron mobility of about 600cm2/V-s, a subthreshold slope of 65mV/decade and ON/OFF current ratio of 9 decades at 5V drain voltage. And the gate delay time is 3.3ns at 10V power voltage, measured from a ring oscillator which has enhancement-load type NMOS inverters having the (W/L) iload- (W/L) driverer of 25μm/15μm - 50μm/10μm.

Chapter 6 - Improvement of Image Quality in AMLCDs

Flight instrument design has begun to include a new, digital electronic technology for the display head: active matrix liquid crystal display (AMLCD). This is a significant design transition and applies across the board to new systems, complete cockpit modernization programs, and individual instrument replacement projects. AMLCD-based instruments are digital and are expected to have a substantially higher mean time between failure compared to both electromechanical and CRT-based instruments, which are typically analog. Thus, the new technology will pay for itself. Furthermore, AMLCDs are truly sunlight-readable and can provide large display areas enabling formats which increase situational awareness. We have the opportunity with this new technology to establish a common critical item products for sunlight-readable, color and greyscale capable, flat panel displays for military applications. >