Electronic Design

LCD TVs Get Ready To Take Over The Market

As recently as 2004, TVs based on cathode ray tubes (CRTs) dominated the market, with over 90% of total TV shipments worldwide. LCD, plasma, and microdisplay (MD) technologies combined added up to less than a 10% share. Worldwide, 2004’s TV shipments totaled 183 million units and increased to 187 million in 2005.

What a difference a year makes. CRT TVs captured the largest portion of shipments, but its share dropped to 83%. Meanwhile, LCD TV shipments soared 141% year to year to 21 million units and captured an 11% share. Other technologies also chipped away at CRT TV’s share, but the big winner was LCD TVs.

According to DisplaySearch’s Quarterly Global TV Shipment and Forecast Report, Q3’06, 2007 will be another banner year for LCD TVs. LCD TV shipments are expected to more than double to over 44 million units, taking a 23.6% share of total worldwide shipments.

CRT TV shipments will be about 131 million, about triple the size of LCD TV shipments. Yet CRT TV’s dominance will finally fall some time in 2008 when LCD TV shipments take the lead for the year with a 46.2% share versus CRT TV’s 44.9%. Next year, LCD TV shipments will hit 70 million units. In terms of units, LCD TVs will dominate the future.

LCD TVs will dominate the market because the amount of investment toward building production capacity for LCD TV panels is an order of magnitude higher than the investments for any other display technology.

DisplaySearch’s Quarterly Supply/Demand and Capital Spending Report, Q3’06, says that total spending on thin-film-transistor (TFT) LCD manufacturing equipment, excluding facilities, totaled over $13 billion in 2004—the height of investment spending for the LCD industry. In 2005, TFT LCD equipment spending totaled more than $10 billion. It will remain at that level through 2007, after which it will begin to slowly decline.

Also, the variety of size is a factor in LCD TV’s success. Among currently shipping models, there are about 30 different sizes ranging from a diagonal size of 10 in. all the way up to 65 in. Of course, much larger sizes are being developed. During this year’s Society of Information Displays (SID) conference in San Francisco, LG Philips LCD (LPL) showcased a 100-in. prototype LCD TV.

The variety of sizes means manufacturers can meet the overall market demand as well as demand from niche applications. Smaller sizes suit kitchen-countertop TVs, while 65-in. LCD TVs fit home-theater applications. At very large sizes, other display technologies such as liquid crystal on silicon (LCoS), Texas Instruments’ Digital Light Processing (DLP), and LCD rear projection have been and currently are very strong. That’s because they can increase the projected image size easily without adding much cost.

High definition (HD) is another factor that plays to the strength of LCD technology. Resolution increases from 480 horizontal lines in standard definition (SD) to either 720 or 1080 lines for HD. LCD technology is well poised to handle HD’s increased resolution. Due to smaller bandwidth requirements that allow broadcasting, cable, and satellite companies to offer more channels, the 1080i HD standard has been largely adopted.

To view 1080i without scaling down the video content, the display will need a pixel format of 1920 by 1080 based on a 16:9 aspect ratio. Plasma technology has difficult technical barriers in achieving a pixel format of 1920 by 1080 in the 40- to 50-in. range. On the other hand, several brands offer 40-in. LCD TVs and smaller sizes capable of displaying 1080 lines.

Scaling the resolution up to 1920 by 1080 at smaller sizes is one of the advantages that LCD technology holds over plasma. By 2010, more than 25% of all LCD TV shipments will have 1920- by 1080-pixel format, compared to 12% for plasma TVs. Projection technologies such as LCoS and DLP will have a significantly higher portion at 92% due to their much larger sizes.

All of this technology doesn’t mean much if HD content doesn’t look good on your LCD TV, though. Many technologies work together to generate a sharp, beautiful image on an LCD TV, and at the core is the light source. LCD’s primary source of light for notebook PCs, LCD monitors, and LCD TVs has been based on a technology called cold cathode fluorescent lamp (CCFL).

CCFLs today power nearly 100% of backlights in LCD panels used for notebook PCs, LCD monitors, and LCD TVs. CCFL technology offers low price, an average lifetime of 50,000 hours, fairly low power consumption, high brightness efficiency, and good color uniformity. Consequently, it’s become the de facto standard for nearly all large-area LCD backlight applications.

With recent changes in the political and competitive climates, a couple of issues regarding CCFLs have surfaced: the use of mercury and relatively restricted color gamut. The European Union’s Restrictions on Hazardous Substances (RoHS) limit the use of mercury and other materials. A small amount of mercury is required to generate light in a CCFL. When a high voltage is applied to electrodes in a CCFL, mercury and internal gases are ionized, producing ultraviolet light with a 254-nm wavelength.

Light-emitting-diode (LED) technology is challenging CCFL by offering better power consumption, an enhanced color gamut, and a mercury-free source of light. Compared to CCFL’s average color gamut of 72% NTSC, LED-based backlights can provide more than 100% NTSC. Even though LED provides many benefits over CCFL, adoption has been slow due to higher costs and heat-related issues.

Aside from the majority of mobile phone displays that incorporate LEDs, very few large-area applications use LED backlights. Sony’s TX-series notebook PC uses a TMDisplay-developed, LED-based, 11.1-in. TFT LCD panel. Also, an LED-based backlight illuminates Samsung’s LE40M91 40-in. LCD TV.

Due to competitive pressures, CCFL manufacturers have improved the color gamut to over 90% NSTC by enhancing the phosphors, reducing an advantage of LED technology. Many LCD manufacturers incorporate LED backlights into a small number of LCD panels. DisplaySearch’s Quarterly Backlight Lamps & Backlight Units Report, Q3’06, says LED backlights will capture just over 5% unit share by 2010.

Many other factors determine picture quality on an LCD TV, like lower-viscosity liquid crystals, faster frequencies, over-driving circuitry, and black frame insertion. Yet with advances in illumination combined with HD resolution, we can expect a bright, thin display that features high color fidelity, long lifetimes, and lower power consumption in future LCD TVs.

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