Large-Area Displays Shift Focus from Biggest to Best at Display Week 2007

LCDs remained the most-prominent large-area display showcased at Display Week 2007, with more focus on quality than strictly pure size.

by Carl Cobb

THE nearly constant sunshine that greeted attendees at Display Week 2007 in Long Beach, California, in May, served as an apt analogy for the growth in volume of the liquid-crystal displays (LCDs) that were showcased both on the exhibition floor and in numerous technical papers. Although LCDs continue to be responsible for the lion's share of unit shipments and revenues in the large-area-display sector, turning a profit on these units presents a much cloudier picture, especially as so much new fab capacity comes online and panel makers continue to rapidly ramp up production.

This continues a trend that began in 2006. At Display Week 2006, the introduction of ultra-large displays from newly opened Gen 7.5 and 8 fabs heralded the era of megafabs with high productivity. For competitive purposes, particularly in the larger LCD-TV sizes, the imperative is to grow larger or fall behind. During 2006, major new fabs began operation at Samsung and LG.Philips LCD in Korea, and AU Optronics (AUO) and Chi Mei Optronics (CMO) in Taiwan. As expected, these larger fabs allowed for greater productivity and lower costs, yielding lower prices. However, an unexpected byproduct of this development was lower profits, as many panel manufacturers tried to squeeze through the market window at the same time.

During 2007, some companies have adjusted their capital-expenditure plans, leading to a projected shortage of capacity in 2008 and a firming of prices and profits forecast for the second half of 2007. So, as one "crystal cycle" ends, another begins.

With those market forces as a backdrop, here is a look at the developments in the large-area-display arena at Display Week 2007.

p26a_tif p26b_tif Sharp Corp.

Fig. 1: Examples of Sharp's LCD digital-signage monitors.

 


Carl Cobb is a Senior Partner at the McLaughlin Consulting Group (MCG) located in Menlo Park, California, specializing in the display industry; telephone 650/366-5999, e-mail: carlcobb@mcgweb. com.

 

Large LCDs

As has been the case in recent years, large LCDs were very visible on the exhibit floor. The emphasis this year shifted from the "biggest" screens in 2006 to the "best" displays in 2007. Samsung showed a 70-in. model and said it was the largest LCD "for mass production." Sharp showed a new series of portrait full-high-definition 46-, 52-, and 65-in. displays (Fig. 1) targeted at digital signage, which is currently the fastest-growing segment for jumbo LCDs. These offered selectable power and interface modules rather than the complete complement of entertainment interfaces, cutting costs and allowing more flexibility. LG.Philips LCD showed a wide range of panels, including 37-, 42-, 47-, and 52-in. models.

Motion Blur

One of the remaining performance issues of LCD TVs is motion blur, due to the hold nature of an LCD as opposed to the impulse drive of cathode-ray-tube (CRT) or plasma displays. Samsung LCD showed its motion-compensation frame-interpolation (McFi) technology on a 70-in. LCD capable of operating at frame rates of up to 120 Hz. The motion-compensation system detects the source as video or a converted film at 24 frames/sec. For video, a single interpolated frame is inserted, yielding a 100/120-Hz rate. If a 3:2 cadence from a film source is detected, the original 24-Hz frames are recovered and two interpolated frames are inserted, resulting in a 72-Hz rate. The display motion was smooth with demo content that featured a fast-moving image sliding horizontally across the screen. Few details about the implementation were available on the floor.

LG.Philips LCD also showed a similar set of motion-blur-reduction capabilities, driving the panel at 120 Hz and doing interpolation of intermediate frames. As with the Samsung display, the motion was fluid and natural, without visible motion blur.

Toshiba Matsushita Display Technology Co., Ltd. (TMD) showcased an alternative approach to blur reduction – a very-fast 32-in. display based on optically compensated bend (OCB) mode liquid-crystal operation that has a motion-picture response time (MPRT) of 2.0 msec. This was compared side by side to a CRT with a 4-msec MPRT response. OCB-mode prototypes continue to improve; at Display Week 2006, TMD showed a similar display with a 4.7-msec MPRT.

Color Gamut

The average LCD TVs have a color gamut of about 72% of the NTSC standard. The color gamut is primarily a function of the backlight and the color filters. Standard CCFL phosphors limit the color gamut. In 2006, Sony demonstrated phosphors optimized for a wider gamut. Together with color filters adjusted for these phosphors, Sony achieved 91% of NTSC. In 2007, this approach was demonstrated by Samsung (Sony's partner in S-LCD), LG.Philips LCD, and Sharp, all showing panels with 92% of NTSC. The improvement is visible, but subtle.

p27a_tif Carl Cobb

Fig. 2: This Sony display utilizes Osram's 70-in. LED backlight.

 

p27b_tif Carl Cobb

Fig. 3: Global Lighting Technologies' backlight designs.

This improved gamut comes at the cost of lower luminance since the deeper reds used to extend the gamut have a lower human perception, for the same power, as do the red-orange phosphors used in the standard tri-band lamps. To correct this, 3M promoted its light-control films as a way to regain luminance without adding power (and heat).

LED Backlighting

Light-emitting-diode (LED) backlights are graduating from mobile-display backlighting and are now being implemented in thin, light notebooks. These first implementations are based on white LEDs. Because white LEDs are limited in color gamut, TVs, monitors, and multimedia notebooks employ RGB devices. Sony pioneered the RGB design in 2004, introducing the stunning (in both performance and cost) Qualia 40- and 46-in. models. Since that time, LEDs have rapidly improved in power efficiency and cost efficiency. While not yet mainstream, RGB LED backlighting provides a higher gamut – 105% of NTSC or higher – while enabling greater control of lighting, timing, and color mixing.

Samsung showed its 40-in. production TV featuring LED backlighting; this product was selected by SID as the 2007 Display of the Year Gold Award winner. Osram featured a 15.4-in. notebook display lit by white LEDs as well as a spectacular demo of a 70-in. Sony display backlit by 1152 Osram modules with lens optics optimized for light distribution in a direct backlight (Fig. 2).

Along with the progress of LEDs, backlights are advancing in the development of light management. LEDs are point sources, and achieving uniformity in backlighting is a challenging two-dimensional problem instead of the nearly one-dimensional light dispersal sufficient for cold-cathode fluorescent lamps (CCFLs). To support LED backlighting, Global Lighting Technologies (GLT) showed proprietary software and backlight designs capable of dispersing an LED point source(s) to an evenly lit backlight field (Fig. 3). In private showings, GLT was showing an edge-lit backlight prototype for a 52-in. LCD TV using Luminus Devices' photonic lattice LED modules. Optical Research Associates (Light Tools) and Zemax both demonstrated commercial software for LED-backlight design using non-sequential ray tracing.

Dynamic-Range Expansion

When the LEDs are located behind the LCD panel, they form a cavity backlight, which can be modulated by area of the screen or even down to individual LEDs. Modulation of the backlight output, combined with gamma stretching based on video content, is becoming a common way to increase dynamic range and reveal gray-scale detail. This high-dynamic-range (HDR) technology is implemented at the display-system level and depends on analysis of the video stream as well as modulation of backlight luminance and driver gamma. BrightSide/Dolby Technologies demonstrated an LCD TV with modulation of the individual LEDs, and it looked impressive.

Plasma-Display Panels

The rapid growth of the LCD business is having a significant impact on competing large-area-display technologies, notably plasma-display panels (PDPs) and rear-projection TV. Starting with a falloff in sales at the end of 2006, PDPs have been scrambling. The 42-in. segment – once dominated by plasma – is now being fiercely contested, with LCDs gaining the leading share. While standard PDPs (1024 x 768 resolution) are still less expensive than comparable LCDs, in the full-HD sector, LCDs are more competitive in the 40-in. segment. Only Samsung SDI exhibited a PDP this year: full-HD 50- and 63-in. models with 1000:1 contrast, high brightness (1000 nits), and 10-bit color (Fig. 4).

Conclusion

The global display market is forecast to top $100 billion this year, thanks in large part to the flat-panel display's conquest of 100-year-old CRT display technology for TV. This is a demonstration of Joseph Schumpeter's concept of "creative destruction" that describes a process whereby the new devours the old order, thereby revolutionizing the economic structure from within. The LCD industry is growing larger and showing initial signs of a balance between growth and profitability. There seems to be a greater emphasis on refinement while continuing the pace of cost reduction. PDPs are under pressure, but still are expected to be dominant in the 50-in. and above arena. OLED technology as well as other new technologies continue to develop, trying to be the catalyst of a new round of creativity and a further change in the market order. •

p28_tif Carl Cobb

Fig. 4: Samsung SDI's 50-in. HD plasma-display panel.