The most conspicuously visible aspect that excites most customers about today’s electronics products is the display. Be it a new cell phone, tablet, television or laptop, the first thing that people look at is how bright and clear the display is. Understandably, the displays are fast evolving. Even as older screens are giving way to high-definition (HD) ones, quad HD and ultra HD are already on their way. Whether you are a fan of liquid-crystal displays (LCDs), light-emitting diode (LED) displays or Plasma screens, there is some improvement happening every day in their performance or clarity.
That said, the current generation of mobile users has triggered a fresh set of parameters for evaluating displays, and a brand new set of challenges for display makers and researchers. Interactivity has emerged as a key requirement, giving rise to improved touch screens and immersive technologies. The need to conserve battery life has made engineers focus their energy on reducing the power consumed by displays.
As devices are getting packed into smaller footprints, there is also a need to make cooler displays that do not affect the performance of surrounding components. People spending a lot of time outdoors love to watch movies or play games on their mobile gadgets in their free time. This is enforcing the need for higher display performance even in smaller screens.
Likewise, the need to use mobile phones in rugged outdoor environments is pushing manufacturers to come up with displays that show clear images even in bright daylight, robust and flexible displays that are not damaged by a fall, and so on. On top of this, there is the much-hyped 3D trend!
It takes a multi-disciplinary approach to solve these problems and create a perfect experience for the users. Materials sciences, nanotechnology, chemical engineering, physics, electronics, integrated circuit (IC) design and software development are all waltzing together to create the super displays we see today. Much of the magic is, in fact, done by the powerful little chips and code that work in the background. Here is a quick round-up of some interesting display-related developments in the year gone by.
Lighter and brighter touch screens—Apple style
Since people spend a lot of time using technology, they like their devices to be more interactive, with more natural forms of engagement. Some like to give voice inputs, while others like gestures. This demand for interactivity is greatly influencing the touch features of displays.
It is not surprising then that Apple adopted in-cell touch sensing in iPhone 5 despite knowing that it would raise the cost of the phone significantly. A normal capacitive touch screen uses a layer of glass on top and a layer of indium tin-oxide (ITO) underneath it. ITO is transparent and electrically-conductive. When a finger is brought near it, it acts like a capacitor—the capacitive change is detected by the circuitry in the phone, and the finger’s position tracked. Below the ITO layer is another layer of glass, which has a second layer of ITO on it to isolate the LCD screen from electrical noise. So, actually the image has to go through two layers of glass and ITO. Even if you assume the best-quality glass and minimal refraction, some amount of clarity is lost. Plus, having multiple layers also increases the weight.
In-cell multi-touch technology tries to overcome these problems by combining the LCD and touch sensing layers. It integrates touch into the thin-film transistor (TFT) LCD manufacturing process, obviating the need for additional sensors and glass.
Apple appears to have been thinking about this since as early as 2006, when it filed a provisional patent for methods of including touch capabilities in displays. In August this year, they were granted a patent for an extensive application that covered several ideas as well as manufacturing processes that could be used to build the displays. The abstract mentions that there are several forms in which the touch sensing elements may be integrated with the display circuitry: “Touch sensing elements can be completely implemented within the LCD stackup but outside and not between the colour filter plate and the array plate. Alternatively, some touch sensing elements can be between the colour filter and array plates with other touch sensing elements not between the plates.”
Japan Display recently showcased three prototype displays in collaboration with Sony, Toshiba and Hitachi. Hyped as ‘Innovation Vehicles,’ these displays represent the technologies that will be incorporated into products in the recent future. One of the innovative features of these prototypes is the Pixel Eyes technology, which is comparable to in-cell sensing.
According to the company’s announcement at FPD International 2012, “In Pixel Eyes technology, the touch-panel is built in, rather than being attached from outside. The structure becomes simple, so it’s easy to make the display thin. Such a thin display is very sensitive, so we’ve utilised that to enable writing with a pen. Currently, finger operation is the norm, but we would like to provide a pen-drawing solution next.”
A screen that can bulge into buttons
We like to swipe and pinch our screens, but there are still times when we wish for a traditional keyboard experience—say, when typing a long document.
Californian company Tactus Technology together with Touch Revolution seems to have an answer. Their new touch panel looks like the normal touch screen displays on existing handheld gadgets but it uses a tactile layer that sits atop the touch screen. This tactile layer is composed of fluid-filled micro-channels, which can alter fluid pressure and redirect the liquid to create blister-like buttons. Similarly, it can also make the buttons disappear in a jiffy.
This morphing technology can be used to give users a keyboard on-demand experience, by transforming a touch screen’s flat surface into real physical buttons. While in the initial stages the company has preprogrammed the size and shape of the buttons, in the future it will be possible for the user to configure these too. The tactile layer consumes very little power while forming the buttons, but there is no power consumption once the buttons are active.
This technology is expected to be used in products starting 2013.
Touch magic in large, retail displays
It is not just mobile phones and such personal devices that are into the touch fad. Retail displays are also getting a huge touch makeover. Industry experts claim that users are so used to touch-enabled displays in their personal devices that they expect the same interactivity to be extended to larger-format screens as well. What sets this segment apart is the need for robustness—as the displays will be frequently used by several untrained users.
Spice king McCormick recently opened its World of Flavors—a 353sq.m complex at the Baltimore Inner Harbour, in USA, where it has deployed 107cm (42-inch), touch-enabled HP digital signage displays and HP TouchSmart All-in-One PCs. Apart from several digital engagements, including a guess-the-spice game, it has setup an 8.5m (28-foot) wall dedicated to broadcasting McCormick’s past and history of spices and flavours in an immersive experience.
J2 Retail Systems, makers of special digital displays for the retail world, also has some interesting products such as the TFR and Pro-Cap. Their True Flat Resistive (TFR) screen has a bezel-free design that makes it a totally flat, sealed screen that is both practical and stylish. The TFR screen’s IP rating denotes that it can be used outdoors.
For exceptional durability, J2 is also equipping some of its models with Projective Capacitive Touch (Pro-Cap) screens, which apparently come with an almost unlimited touch life. These scratch-resistant glass screens are said to be durable, while also delivering stable performance with exceptional screen clarity and brightness. Pro-Cap screens also allow finger touch inputs such as gesturing, and are unaffected by moisture, temperature or harsh cleaning products. J2 offers touch screens in 5-wire resistive, surface acoustic wave (SAW) and infrared types.
Samsung has created much more excitement with three new technologies unveiled at the GITEX Technology Week held in October this year at the Dubai World Trade Centre: a transparent display (NL22B), a 190cm (75-inch) LED LFD (ME75B) and a 3D video wall.
The NL22B transparent display can be used to create an immersive shopping experience. It may also be used in other fields such as healthcare and education. The 56cm (22-inch) transparent display is a cube-shaped device that contains a transparent front panel with a computer built into the chassis. It allows images and animations to interact with the products showcased inside the cube. So it can be used in a store to allow users to interactively find out more about products, try out various combinations, etc, before making a purchase.
The ME75B is a cutting-edge, huge light-emitting diode (LED) display that is energy-efficient, smart and network-enabled. It can adjust brightness by itself, and has a built-in media player too, which makes it a standalone device. It can be used with a touch overlay and can be implemented at stores or restaurants to provide customers with an interactive guide.
The 3D video wall is a slim, edgelit, high-definition LED panel—another product that will be loved by retailers!
While touch has been throwing its weight all over the display scene, other factors such as resolution and display performance also continue being points of innovation. The issue of performance, for instance, is being dealt with from varied angles—right from the material to the chip and the software.
One interesting example is the Corning Lotus Glass technology unveiled last year. The ecofriendly, high-performance display glass has been developed to support the demanding manufacturing processes of both organic LED displays and LCDs for high-performance, portable devices such as smart phones, tablets and notebook computers. It performs exceptionally well in low-temperature poly-silicon (LTPS) and oxide TFT backplane manufacturing environments.
“Corning Lotus Glass has a high annealing point that delivers the thermal and dimensional stability our customers require to produce high-performance displays,” said Andrew Filson, worldwide commercial director, Display Technologies, and vice president, Corning Holding Japan GK, in a press report. “Because of its intrinsic stability, it can withstand the thermal cycles of customer processing better than conventional LCD glass substrates. This enables tighter design rules in advanced backplanes for higher resolution and faster response time.”
To keep pace with the demand for performance, this year 3M also announced a few high-performance multi-touch displays that extend tablet-like responsiveness to larger, interactive displays. The 61cm (24-inch) M2467PW and the 69cm (27-inch) M2767PW feature brilliant high-definition graphics powered by LED backlights, wide viewing angles and elegant smart phone-like product design. The M2467PW can recognise up to 20 simultaneous touch events. The M2767PW with ultra-fast 40-touch capability is ideal for multi-user applications such as digital signage and product selectors.
Based on 3M’s Projected Capacitive Technology (3M PCT), these multi-touch displays offer the unique ability to recognise and reject the user’s palms or arms resting on the touch screen to help prevent inadvertent touches while also maximising multi-touch functionality. A 3M-proprietary anti-stiction surface treatment allows the user’s fingers to effortlessly glide across the screen for smoother gesturing and accurate draw capabilities.
Microsoft never stands out of any race! This March, researchers at Microsoft claimed to have developed a touch screen display that improves touch screen latency by a factor of 100. Current touch screen displays have an input latency of about 100 ms, which is responsible for the delay we notice between giving the input and seeing it on screen. In a video demonstration, a Microsoft researcher showed a 10ms latency screen that changed the delay of a movable virtual object on the screen to a rubber band impression. This was followed by a 1ms delay version, in which the delay was barely perceivable. However, the company also made it clear that this is still a ‘technology’ and will take many years before it becomes a product.
Readability in sunlight is an important parameter for comparison of mobile device models these days and justly so. This requirement holds even for outdoor displays used for events or promotions.
To improve visibility in sunlight, some general guidelines are that a sun-readable display should be bright enough to be clearly visible under direct sunlight. Its display contrast ratio should also be high. Generally, the screen brightness is of the order of 1000 nits and the contrast ratio is at least 5:1. Plus, some technology should be used to avoid the glare.
Some companies use the combination of a standard display, an enhancement film applied on the internal screen to optimise brightness and contrast, and a polarising film applied on both sides of the touch screen to minimise reflection. The anti-reflective coated protection glass minimises the mirror image and maximises transmittance, while the anti-glare coated protection glass scatters light directed on the surface and softens the image of direct light sources.
Pixel Qi’s transflective technology is one such technology worth watching. It uses a special layer that acts like a partial mirror—part of it transmits the light while the rest of it reflects the light.
One industry expert writes: “It’s like a typical mirror layer found in most displays but with holes punched out in it. This allows for a composite mode where users can adjust the backlight and still see the LCD screen with reasonable brightness.”
This transflective LCD is viewable under all lighting conditions including direct sunlight regardless of the LCD’s original brightness. Also, because the LCD pixels are reflective, the user can turn down the brightness level and save on battery power consumption.
Tru-Vu uses optical bonding to improve daylight viewing on their LCDs. Optical bonding injects a transparent optical-grade epoxy resin to bond a protective glass panel directly to the face of the LCD. This eliminates the air gap between the LCD and the cover glass, drastically reducing the reflections which cause the visual wash-out typically seen in bright conditions. Optical bonding also increases the durability of the LCD monitor by bonding the LCD panel to the cover glass and the monitor’s enclosure. It also avoids fogging due to moisture trapped between the layers.
Eco angles—power, heat, greenness
Users want to use their mobile devices for longer hours on a single charge. So it is critical that these devices consume less power. For larger displays, it is a matter of reducing electricity bills. Hence companies are coming up with several innovative technologies to reduce the power consumed.
For example, this November, Japan Display showcased a reflective LCD panel with power consumption as low as 3 mW at the time of displaying a still image. The panel has a 17.8cm screen and is targeted at mobile devices that require low power consumption.
Japan Display has used a low-temperature polycrystalline silicon TFT as the driver element. It has also included a static RAM circuit on each pixel to retain image data to be written, with the aim of lowering power consumption. Another distinctive aspect of this display is that the company has achieved a natural display like paper by optimising the optical design of the scattering layer.
Materials engineering is also contributing a lot to making cooler and power-efficient displays. An organic LED display, for example, if designed properly uses only 40 per cent of the power of a comparable LCD. Nano-technology has also given rise to better structures, materials and technologies. Cambridge University’s polymer organic light-emitting diode (P-OLED) display is an example, which is extremely eco-friendly and power-efficient. POLEDs are basically OLEDs made with conjugated polymers.
The heat dissipated by the display is also a critical factor. If a display heats up, its basic components wear out faster and the life of the display goes down. If a lot of heat emanates from the display, it will also affect the surrounding parts of the device—this is very critical for mobile devices where the components are packed closely together. A hot device is also difficult to hold in your hand. So this is another point of innovation for display-makers.
Greenness is a universal parameter that almost all industries are focusing on. The eco-friendliness of products is a very important factor as it influences product ratings, customer decisions and the manufacturer’s social responsibility in general. At GITEX 2012, Panasonic was apparently the largest exhibitor and its focus was on eco-friendly products. The company claims that its displays are free of lead, mercury and other toxic substances that can harm the environment.
Little chips, big wonders
It is possible for display makers to quickly design and manufacture products with a range of readily-available intellectual property and programmable components.
The field-programmable gate arrays (FPGAs) available from companies like Xilinx and Altera enable faster adoption and migration to the latest technology and standards, interfaces and codecs due to their programmability and flexibility. This allows manufacturers to evolve from 3D TV to Digital Cinema (4K2K) and ultimately to 8K4K Ultra HDTV (such as what was used in theatres in London to broadcast the Olympics footage this year).
“Emerging display technology is an area where FPGAs are always needed, given the newness of the technology. There has been a tremendous amount of innovation and breakthrough in semiconductor and IC technology relative to bringing immersive display technologies such as 3D TV, LED local dimming and 4K2K (Quad HD) to life,” says Aaron Behman, senior product marketing manager-Broadcast & Consumer Segment Marketing, Xilinx Inc.
He adds, “The precipitation of mobile devices putting constraints on video production and the reach of video networks (to fuel mobile-based insatiable video demands and the like) put the spotlight on FPGAs, which are increasingly the only option to meet the demands of an ever-changing broadcast industry. A growing number of OEMs are adopting these flexible devices because hard-cast silicon solutions like application-specific integrated circuits (ASICs) and application-specific standard products (ASSPs) geared for implementing system integration and video processing, are too expensive and take too long to develop in an era of rapid standards evolution. The combination of programmable devices, market-specific intellectual property, reference designs and hardware boards fosters broad-cast design innovation and algorithm enhancements that deliver real-time capabilities of HD and higher resolutions of Digital Cinema and 4K2K.”
The latest 28nm-based FPGA platforms from Xilinx Inc., for example, are aimed specifically at speeding time-to-market, helping both consumer electronics manufacturers and broadcast equipment designers drive up the quality of video, overcome the challenges of processing and moving uncompressed high-definition, 3D and 4K video streams, and lower costs with minimised bill of materials.
As the next innovation wave—4K2K—breaks into the mainstream, delays to market will result in missed revenue opportunities. Xilinx’s proven reference designs are geared to shorten time to market for highly differentiated and high-performance visual systems. For instance, Xilinx’ Display Targeted Design Platform (TDP) consists of a Kintex-7 FPGA hardware platform with an Acquisition, Contribution, Distribution and Consumption (ACDC) 1.0 baseboard developed by Tokyo Electron Device. The Display TDP enables the stitching together of four 1080i video streams into a seamless 4K2K image by simultaneously increasing performance while reducing power consumption as compared with previous solutions.
Xilinx’ Zynq-7000 family further delivers to customers not just an FPGA or an FPGA with a processor but a truly programmable system-on-chip (SoC) wherein the hardware, software and I/O are each fully programmable. It enables the development of monitors and multiviewers (for example) that require incoming video to be de-interlaced and scaled in real time to support monitor formats up to 4K resolution or in 3D with no loss of video quality. Now multiple windows, 3D graphics for games and immersive ultra-realistic viewing beyond HD, to name a few, are possible—all ultimately changing the way consumers watch and interact with TVs.
Something to look forward to
The display industry is indeed shaping up quite excitingly. Brighter, high-performance, high-definition, low-power, 3D, sun-readable, interactive, immersive—there is just too much happening. And, the trend appears to be on a high!
“There have been a lot of innovations in display over the last several years from electrophoretic displays that are used in eReaders like the Kindle, to new MEMS-based displays like the Qualcomm Mirasol display to OLED displays. All of these technologies will compete against the tried and true LCDs, which will be very hard to displace given the existing investment in manufacturing infrastructure. However, OLED displays are a very competing technology to watch out for, given their power performance and the fact that they can be bent to shape,” says Behman. “4K2K displays, or displays that are 4x the resolution of full HD, are also interesting technologies. These displays will offer more detail than full HD. Many models will be hitting shelves this holiday season in the US.”