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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.
