Over the past few years, TV sets have incorporated numerous new technologies and features, in some cases providing more than consumers have been able to utilize or afford. At the same time, the need to improve profitability and tap into emerging markets has led to TV sets that make explicit performance tradeoffs in favor of lower cost. In the near term, this has resulted in a proliferation of choices. What does this tell us about the TVs that will be available in 2015 and beyond?
by Paul Semenza
SEVERAL different TV technologies – LCD, plasma, and OLED – are battling to become "the CRT of the 21st century," with the LCD currently in the lead. The TFT-LCDs have continued to expand their share of the TV market, having passed 100 million units shipped in 2008 and 200 million in 2011. DisplaySearch forecasts that LCDs will reach nearly 90% of the TV market by 2012. In addition to growing with the overall TV market, TFT-LCDs have also been taking share from the cathode-ray-tube (CRT) market, shipments of which fell below 100 million in 2008 and are expected to approach 10 million in 2012, as even emerging market households convert to flat panels or choose an LCD as their first set.
After growing rapidly in 2010 in response to a stall in LCD price declines, plasma-TV shipments are falling in 2011 and are expected to decline from 18 million units to 14 million by 2015. At that point, plasma-TV makers are expected to focus exclusively on the 50-in. and larger market segment, where plasma displays will maintain cost competitiveness with LCDs. But just as rear-projection technologies were driven out of the market by the economies of scale that flat-panel displays enjoy, the investment in Gen 7 and larger TFT-LCD fabs, combined with a lack of investment in plasma, make it likely that LCDs will eventually drive it out of the market.
This leaves the question of the potential for organic light-emitting-diode (OLED) based TV. In theory, OLED displays have the superior image quality (color gamut, viewing angle, and response time) of an emissive display, but at lower voltages, simpler structure, and far fewer materials than other emissive displays (CRT and plasma). At the same time, it is an active-matrix technology and can build on the TFT-manufacturing technology developed for LCDs. Instead of combining an active matrix with a complex system of creating and then shuttering light – as TFT-LCDs do – active-matrix OLEDs (AMOLEDs) can emit the color, brightness, and duration of light as needed. In theory, AMOLEDs should be able to compete effectively with TFT-LCDs and eventually take over the TV market.
In practice, bringing AMOLEDs into mass production has not been simple. Manufacturing TFTs that can provide the needed levels of current across a large substrate, and developing processes for depositing the organic materials at high density on such substrates, have proven to be difficult.1 At present, there are more than two-dozen TFT-LCD fabs of Gen 6 or larger (factories that are optimized for 32-in. and larger panels), but there is only a single Gen 5.5 AMOLED fab. It will be many years before there will be anywhere near as many AMOLED fabs, even considering the possibility of conversion of existing TFT-LCD plants. Given the cost advantage from large-scale manufacturing, TFT-LCDs are likely to continue to be lower cost than AMOLED displays in TV panels for some time to come.
DisplaySearch forecasts that OLED-TV shipments will begin again (there were some shipments in 2007) in 2012 and will approach 3 million by 2015, which will account for approximately 1% of TV shipments. It is likely that 2015–2020 will be a key period for OLED TV to gain market share and represent significant competition for LCD TVs. However, in addition to the challenges of moving into high-volume manufacturing, OLED technology will have to compete with the ever-improving TFT-LCD technology.
In recent years, LCD performance has improved in the areas where OLED displays have been assumed to be superior. A key advance has been the development of LED backlights, which have enabled increases in color gamut and contrast ratio, as well as greatly reduced panel thickness. In conjunction with faster liquid-crystal materials and driving circuitry, LED backlights also enable higher frame rates. Another area of significant improvement has been wide-viewing-angle operation, enabled by advanced TFT architectures such as in-plane switching (IPS) and fringe-field switching (FFS).
Will "High Definition" Become "Medium Definition"?
An ongoing area of development in LCD TVs is in resolutions beyond full HD (1920 x 1080), with 4K x 2K and 8K x 4K sets having been demonstrated. Most demonstrations to date have utilized TFTs based on metal-oxide semiconductors, a promising approach that could also be utilized as an active matrix for AMOLEDs. There will be challenges for each of these technologies to realize such high resolutions: for LCDs the challenge is that the backlight brightness must be increased significantly; for OLED displays, there are no proven methods for depositing organic materials at such high densities.
In order for TVs with such high resolutions to become commercially useful, significant expansions in video capture, creation, storage, and transmission systems will be required. It is also important to realize that years into the transition to HD, most content is still in 720p or other formats below full HD, but it is likely that HD will not remain the highest – or even the standard – resolution forever.
3-D Will Need to Lose the Glasses
Another area of rapid development in flat-panel TVs has been 3-D, with intense competition between active- and passive-glasses-based systems. Active systems present left and right images in a time-multiplexed fashion and use switching glasses to select the image, while passive systems use spatial multiplexing in conjunction with polarizing glasses. Both approaches involve compromises – the switching in active systems can lead to flicker, crosstalk, and other effects, while passive systems avoid these issues but at the possible expense of resolution, a topic of some debate.
While the adoption of 3-D has been slower than many TV makers had hoped, it is likely that 3-D will become a standard feature in flat-panel TVs. Over the next few years, increasing availability of 3-D content will create a concomitant demand for 3-D capability, while the existing technologies will continue to improve.
It is clear that a significant barrier to broader adoption of 3-D has been the requirement for glasses. Thus, in the longer term, the most important development will be in autostereoscopic technologies, which do not require the use of glasses. Autostereoscopic displays developed thus far have not had the performance required for TV, but perhaps in conjunction with the emerging high-resolution displays, it is likely that such products will be available over the next 5–10 years.
TVs Need to be Connected – But How Smart Do they Need to Be?
With the proliferation of content beyond conventional broadcast, cable, or satellite access, connectivity of the TV has become an increasingly important feature. Connectivity has many forms, including the physical aspect (wired, wireless) and the scope (point-to-point, local network), as well as the location of the intelligence – in the TV or a connected set-top box, Blu-ray player, game console, or other device. It is clear that TVs must be able to connect to wired and wireless devices in the home, as well as the Internet, either directly or through an auxiliary device.
Through much of the history of the TV, the sets have been monitors – playback devices connected to a signal, set-top box, or video source. Often, new features are integrated into the set when first introduced, but soon move into a dedicated device that can be upgraded separately from the TV set. Connectivity is the latest example of the tension between embedding features in the set as opposed to an external device. The concept of Smart TV has been promoted by set makers as the way to provide the highest level of integration of content sources, from broadcast/ cable/satellite, to media players, to content from the Internet, to content from mobile devices such as smartphones and tablet PCs.
The increasing use and integration of mobile devices to consume video and other "TV" content has led to increasing attention paid to the interactivity of the TV with other devices. Several TV brands, as well as Apple, have promoted interactivity between their mobile devices and TVs or set-top boxes. This can include sharing/streaming of video content, programming, and storage. Of course, these devices can, in some cases, supplant the TV, particularly in rooms where a smaller, secondary TV might have been used before the advent of mobile devices.
"Touch" TV Is Likely Impractical
In addition to the TV becoming more interconnected with networks and other devices, it is likely that more powerful and flexible ways for viewers to interact with and to control TVs will be developed. Due to the distances at which users interact with their TVs, it is not likely that touch screens will become prevalent. However, gesture recognition has already proven to be a powerful and intuitive user interface, as implemented in the Microsoft Kinnect for its Xbox game console. Surely, this technology will improve in the future, possibly using facial recognition to allow for customization of the user interface.
Another form of control that is currently available is to use devices such as smartphones, tablet PCs, or personal media players as remote controls, potentially allowing viewers to use the mobile device to monitor programming other than what is on the TV or to take the current programming with them when they are out of sight of the TV.
Too Many Choices?
Currently, there are two broad themes in TV development. On the one hand, the industry has pushed rapidly to drive adoption of full HD, high frame rate, LED backlit, 3-D, and connected TVs, with the hope that consumers will pay a premium for such features. However, perhaps due to high penetration and difficult economic conditions in developed markets, consumers have not embraced all these features enthusiastically, and price elasticity appears to have declined. In a study of over 14,000 TV owners in 13 countries, DisplaySearch found that the key drivers causing respondents to replace a TV over the last 3 years focused on improving the picture quality, getting a new flat-panel TV, and upgrading to a larger TV. New features such as 3-D, LED backlighting, and Internet connectivity did not drive consumers to upgrade, though they may be valued features if a consumer is already in the market for a TV. The study found a slightly larger, though still minor, impact of these features on purchases planned in the next 12 months.
At the same time, with the increasing share of emerging markets in the global TV business, a new set of designs, grouped under a term called EMTV (emerging market TV), are starting to have a noticeable and very different influence. Here, the idea is to make the set more affordable and provide a logical step up from existing CRT sets. Generally, these sets trade off the high-performance features in favor of simplicity of manufacturing and lower cost.
One approach is to eliminate much of the backlight unit in favor of a simple array of LEDs behind the panel. This lowers costs for light-management components; by reducing the brightness specification, fewer and/or lower brightness LEDs can be used, also saving cost. So-called "direct-type LED" sets can be sold for a modest premium over that of CCFL-based sets, with the tradeoffs being increased depth and reduced brightness. A variation in this design uses a single CCFL tube in a very deep case that is close to the depth of a CRT, leading to the name "chubby TV." This design seems to be targeted at current CRT owners who would like to move to flat panels but at a very modest premium. Another design seeks to approximate the performance of 120-Hz LCD TVs by using a cheaper 60-Hz panel in conjunction with a scanning backlight. This opens up the potential for a more-affordable 3-D TV.
These opposing trends are resulting in a proliferation of LCD-TV designs, as can be seen in Fig. 1. When all possible combinations of the performance attributes at the bottom of the table are combined with the wide variety of screen sizes, there are over 50 different set types possible.
Fig. 1: Current LCD-TV designs vary widely; many possible combinations are shown. Source: DisplaySearch.
The Ultimate TV
Today, the "ultimate" TV is a flat-panel set with high frame rate (at least 240 Hz), 3-D capability, and Internet connectivity. What might the ultimate TV look like in the future? By 2015, we can expect much higher resolutions to be available (at least 4K x 2K), enabled by new backplane technologies. Some of the additional resolution will likely be utilized to implement glasses-free (autostereoscopic) 3-D. The TV will likely be "smart," meaning that it can operate on the open Internet, network with devices including fixed sources (pay TV and streaming set-top boxes, game consoles, and PCs), and mobile devices (smartphones and tablet PCs) and run apps, widgets, and other software providing advanced user interfaces and programming discovery and recommendation functions.
This TV set will likely use an LCD panel made with a lower-cost TFT technology such as metal oxide, with advanced LCD modes enabling wide viewing angle and high transmittance, as energy efficiency will continue to be a requirement. The set will benefit from continued developments in LED devices and color-conversion materials. Looking past 2015, we can expect OLED TV to have made noticeable inroads into the TV market, and to start to compete for the "ultimate" TV by exploiting its inherent ability for wide viewing angle, high color gamut, and high-frame-rate operation in a thin form factor. In order to be successful, significant gains will have to be made in large-area deposition of organic materials at high densities. But OLED TVs could also offer features that would be very difficult for LCD TVs to match, such as paper-thin form factors – and even flexibility – if processes such as plastic or metal-foil backplanes and thin-film encapsulation can be brought into mass production.
One aspect of TV sets that seems destined to change less than many expect is screen size. While average screen sizes will certainly increase as the cost of 40+ and then 50+ in. flat panels falls, and as higher resolutions mean that larger screens will not necessarily imply longer viewing distances, the ultimate limit on screen size is not technological. Rather, it will continue to be limited by things such as architecture and living patterns. As shown in Fig. 2, there is a wide range in the average size of TVs in households across different countries and within countries such as China. Additionally, the availability of alternative devices, such as tablet PCs, for viewing TV content could indicate a trend toward "personal" TVs sized for single-user viewing from a short distance.
Fig. 2: The average screen size of TVs as reported by a multi-nation consumer survey shows viewers in urban areas of China enjoying the largest sizes and viewers in India the smallest. Source: DisplaySearch, Global TV Replacement Study.
While display technology will continue to evolve, it will become increasingly important for the TV to allow for customization by the viewer. The definition of the "ultimate TV" will likely differ with the type of consumer (age, income, and lifestyle), the region in which the consumer lives, the location of the TV in the home, and other factors. If TV sets do not evolve with the changing ways in which content is accessed, it is unlikely that consumers will value them highly, raising the possibility that they will continue down the path of commoditization.
References
1For a discussion of developments in AMOLED manufacturing, see, P. Semenza, "Can OLED Displays Make the Move from the Mobile Phone to the TV?" Information Display 7&8 (2010). •