Mallinson: Displays are the unsung heroes in the smartphone revolution

Mobile communications has progressed leaps and bounds over the last decade, with improvements in networks, operating systems, processors and communications platforms, and expanding ecosystems of applications developers. Advances in displays are also most significant with introduction of colour, increased gamut (i.e., more colours), higher resolution with greater pixel densities, faster response required for full motion video and graphics, and multi-touchscreen capabilities.

High performance including all the above is available with the latest TFT-LCD smartphone displays. However, this comes with the penalty of relatively high power consumption unless one is willing to sacrifice colour or motion performance by selecting an alternative technology, as one typically does in ereaders such as Amazon's Kindle. Overcoming these compromises is the next frontier in display technology development.

A picture is worth a thousand words

Enormous improvements in display technologies employed in phones have been no less significant, though rather less prominent, than the introduction of 3G and 4G radio technologies, high-level operating systems, multimedia applications processors and Apps stores stocked by thousands of developers. The exhibit below shows development of mobile phone technologies and usage has resulted from a virtuous circle of various significant and complementary factors. Smartphone capabilities, their adoption and usage only thrive as they do today because of technological and commercial advancements on several fronts.

Virtuous Circle of Innovation, Adoption and Usage in Mobile Phones

Source: WiseHarbor, 2012

Japanese mobile operators pioneered the mobile Web from around the millennium including the 1999 launch of NTT DoCoMo's very popular i-mode service with tens of thousands of sites accessible via a micro-browser. However, the corresponding, monochrome-only WAP browser experience curried little favour from European or U.S. users. Mobile Internet did not take off in Europe or the U.S. until long after the introduction of colour screens from around the end of 2001, with Ericsson's T68 including a 1.7-inch (diagonally) CSTN-LCD screen providing 256 colors and 101 x 80 pixel resolution, and Nokia's 7210 with 1.5-inch CSTN-LCD screen providing 4,096 colors and 128 x 128 pixels. Despite initially lagging behind Japan in mobile Internet adoption, by 2004 European and U.S. consumers were demanding, for example, phones capable of taking, displaying and transmitting photos, displaying graphic images and playing games. However, CSTN screen technology suffered from poor dynamic performance with motion blur and "ghosting" effects on video. Within a few years, CSTN-LCD technology was largely superseded by the TFT-LCD technology, widely used in TVs, to support moving video and graphics. Dynamic performance on TFT-LCDs has continuously improved to support increasing video frame rates.

Display sizes gradually increased to exceed a couple of inches with, for example, the 2.2-inch screen Motorola RAZR V3 and with BlackBerry screens around 2.6-inches being introduced over the following few years. But multimedia activity remained a significantly offline activity in Europe and the U.S., with occasionally downloaded games, pictures and video clips. Non-voice network usage continued to be dominated by SMS on most phones and email on BlackBerries until smartphones really took off with massive data network growth following the introduction of Apple's iPhone in 2007.

Significantly, the first iPhone model owed much of its success to its rather large 3.5-inch TFT-LCD capacitive multi-touchscreen with 16,000,000 colors and 320 x 480 pixels. This iconic smartphone also included Wi-Fi, a slick operating system and unique, screen-based, user interface software. Until the iPhone, screens were almost invariably coupled with mechanical keyboards. Apple made a success of on-screen Qwerty with touch. Multi-touch, with scrolling and zooming, enabled access to regular Web pages and eliminated the previous need to adjust web content for the particular mobile phone screen. The iPhone's application processor was unremarkable; and the baseband modem was only 2G. With 690 x 960 pixels, the latest iPhone 4S model has four times more pixels than the 2007 iPhone, 40 times more than the Nokia 7210 and 80 times more than the Ericsson T68 launched one decade earlier. As screens have grown in size diagonally, the devices in which they are incorporated have become fashionably thinner and thinner; significantly due to reductions in display module thickness.

What's showing next?

With crystal clear definition and excellent dynamic performance, power consumption remains a bugbear on smartphones because battery capacity is always in short supply on small devices. Power is also significantly demanded by on-board communications, applications and graphics processors. Back-lighting and side-lighting works just fine with modest ambient light indoors, but screens for use outdoors in bright sunlight need alternative designs to conventionally-lit TFT-LCD displays. 

TFT-LCD screen technology has predominated in mobile phones for the last decade, but there are significant rivals. Samsung currently favours Super AMOLED technology in its devices including the Galaxy Note--on the fringe between a smartphone and a tablet--including a 5.3 inch screen with 1280 x 800 pixels. E-ink has been popular with ereaders such as the Kindle. Qualcomm's Mirasol technology consumes a small fraction of the power taken by a TFT-LCD display and has a colour gamut and dynamic performance that, while falling short of TFT-LCD performance at this early stage in its development, significantly exceeds that of other low-power rivals.

Competition with innovation among display providers is as fierce as it is in baseband modems, application and graphics processors, operating systems and user interfaces. In a similarly dramatic way to various flat-screen technologies eliminating CR tubes from TVs and monitors within a decade, disruptive technologies and vendors most likely can and will--within years, not decades--significantly substitute new for existing mobile phone screen technologies, while also making obsolete much of the plant used to manufacture the latter.

Keith Mallinson is a leading industry expert, analyst and consultant. Solving business problems in wireless and mobile communications, he founded consulting firm WiseHarbor in 2007. WiseHarbor is publishing an annual update to its Extended Mobile Broadband Forecast in May 2011. The new forecast will include network equipment, devices and carrier services to 2025. Further details are available at: WiseHarbor on Twitter @WiseWarbor.