Viewing angle technologies and LED backlit notebooks

According to the latest DisplaySearch Quarterly Wide Viewing Angle Technology Report, vertical alignment viewing angle technology continues to lead in wide viewing angle technologies.

In Q1’10, VA technology accounted for 42.2% of the area of large-area TFT LCD shipments, up from 36% in Q1’08.

Most LCD TV panel makers have adopted VA technology for panel production of 32″ and larger sizes, including Samsung (with technology called PVA), Sharp (Advanced Super View or ASV), AUO (advanced multi-domain vertical alignment or AMVA) and Chimei Innolux (multi-domain vertical alignment or MVA).

Other panel makers like LG Display, IPS Alpha and BOE use in-plane switching or fringe-field switching technologies to achieve wide viewing angles.

The technology commonly found in LCDs is twisted nematic, in which typical viewing angles are 120° horizontal and 90° vertical. This technology is mainly used for notebook and mini-note PC panels since the viewing angle is not critical.

To improve the horizontal viewing angle of TN panels, some makers add wide view film to the panel, an approach used for LCD monitors and smaller LCD TV panels.

High-performance IPS and VA panels accounted for a very small portion of monitor and notebook panels, while the VA type accounted for more than 60% of LCD TV panels.

In terms of panel maker shipments by wide view angle technology, LG Display led in IPS/FFS with 88% area share, and Samsung led in the VA category with 39%. LG Display is the champion of TN with 29% area share in Q1’10. Samsung and Chimei Innolux are leading in TN+WVF, both with a 22% share.

According to Yoshio Tamura, vice-president of DisplaySearch and author of the report, “Each viewing angle technology uses a liquid crystal recipe, cell design layout, TFT structure, manufacturing process and components (like driver ICs).

"Because panel makers own patents on these wide view angle technologies, it can be difficult for new manufacturers to use the available technologies.”

Wide view angle technologies also influence the panel transmittance rate, which is currently a critical factor for LED backlights. VA and IPS/FFS are more challenging technologies and have higher costs than TN, but panel makers’ learning curves are also changing.

For example, some panel makers have changed from TN to VA in 26″ panels, given that VA technology is maturing and the cost gap is reducing rapidly.

“In the future, we believe the key points to watch for are which wide viewing angle technologies new China TFT LCD manufacturers adopt and how fast they can shorten the learning curve,” Tamura added.

Another report from DisplaySearch says the market for slimmer notebook PCs with LED backlights (including 9.1″ and larger mini-note PCs) is forecast to double its share, from 16% in Q1’10 to 31% in Q4’10.

According to the latest Quarterly LED Backlight Panel Shipment & Forecast Report, LED backlight penetration in notebook PCs grew rapidly from 36% in Q1’09 to 81.5% in Q1’10.

Looking ahead, notebook PC panel makers are expecting to nearly eliminate CCFL-backlit notebooks from the notebook PC market by 2011.

Two types of notebook LED backlights exist: slim and wedge type. Both use different light guide plate technology from traditional designs. The slim format reduces the panel thickness to 3.0-3.6 mm, while the wedge type is in the 5.2-5.8 mm range. Despite this, slim LED backlights for notebook PCs require higher quality and thinner components, such as LED array and LGP, compared to the wedge type.

“There has been limited availability of slim LED backlights as a result of limited yield rates of the light guide plates,” noted Anita Huang, DisplaySearch analyst for notebook PCs and panels in Taiwan.

“The $5 cost premium of slim-type panels and the difficult assembly as a result of the fragility and thin form factor have presented challenges.”

Huang added, “Despite the higher cost and assembly issues, the slim type will continue to grow as a result of notebook manufacturer priorities for slimmer form factors over cost premiums. As the yield rate improves, and the economies of scale for the slim type grow, we expect that the slim-type premium will be reduced.”

To create a differentiated market segment, some panel makers are promoting a full product line-up of slim-type notebook panels this year and are trying to shrink the panel price gap between slim and wedge as the slim volume increases.

Hidetoshi Himuro, DisplaySearch director of IT market research in Japan, said: “The slim-type backlight has advantages such as a shorter interface connection cable and easier electromagnetic interference management. Meanwhile, the slim-type panel design also benefits from the assembly locations for the wireless LAN antenna and other cables.”

In Q1’10, only 6.6% of the LCD monitor panels shipped had LED backlights. In LCD TV, the penetration of LED backlights soared from 3.8% to 9.3% in Q1’10. LCD TV panel makers are aggressively targeting a 36% LED penetration in Q4’10, while currently there are still some challenges happening in the LED backlight supply chain.