Emerging Displays – touch screen panel
August 19, 2010, San Jose, CA – The Emerging Display Technologies Conference presented a panel focusing on touch panel technologies. Jennifer Colegrove from DisplaySearch moderated the panel which included Mark Mendenhall, president of ELO TouchSystems, Vincent John Vincent, president of GestureTek, Klony Lieberman, chief scientist at Lumio, Jeff Han of Perceptive Pixel, and Larry Mozdzyn, CTO at Ocular.
Mendenhall described the development and integration processes for a wide range of touch technologies. Technology has to be targeted to the application and the industry is increasingly adding new applications. The range of uses calls for a diversity of technologies, since there are no universal technology.
ELO started with resistive touch technology and added SAW (surface acoustic wave) in ’95. SAW is good for public applications but doesn’t allow for a stylus and requires special glass. In ’05, they added projected capacitive technologies which are useable in both wet and dirty environments. Recently, they added acoustic pulse recognition (APR) for interactive digital signage on large size displays. APR is a fairly high resolution technology that can recognize stylus inputs. Their latest areas of interest are in optical and multi-touch systems. Because there is no perfect touch technology, they partner with others to develop and deploy multiple technologies. Custom and hybrid technologies are an option for complex touch applications.
Vincent noted that there are many types of interaction possible in digital signage. For large displays, attention-grabbing interactions need to be immersive, recognize gestures, and allow point-to-control functions. Integrating the user’s image into the display permits greater interaction and by using front-facing cameras to locate the user’s hands, allows for touch functionality to be used on a large display. Some applications include weather forecast animation, gaming, and education.
Using cameras to capture gestures enables the system to respond to both gross and fine movements. For example, a store display could recognize a person has stopped and respond to hand movements towards an option they pointing to on the display, when they are near the screen. With the right software, this recognition can be extended to multi-user and multi-gesture functions.
Lieberman continued the exposition on optical touch screens. One challenge is that the cost of on-screen touch sensing is proportional to the display area whereas optical based recognition is proportional to the perimeter of the display. Optical sensors can handle in- and out-of plane capture as well as multi-touch. They also don’t require any overlay on the screen surface. By placing a camera at the upper corners and illuminating the work surface with IR, you can get high resolution and detect about 1.7 touch responses. True multi-touch requires additional sensors or mirrors as virtual sensors and very strong object recognition algorithms.
Mozdzyn advocated projected capacitive panels as the best overall solution. He described the basic construction of a capacitive panel and noted the many advanced capabilities for capacitive panels. Applications include multi-touch, stylus or glove operation, durability and reliability, and the ability to tailor the advanced controllers for custom solutions.
The first question to the panel was about differentiation. Mozdzyn responded that performance and the understanding of the application was important. Mendenhall added a breath and depth of technologies as well as partnerships are important contributors. Vincent suggested that the IP in optical permits diversity in uses. By using cameras as sensors, the touch functions can be scaled to very large displays. Lieberman noted that technology and performance are the critical parameters. Han opined that excellence and innovation are the keys. If the vendor starts out at the high end of functionality, he can work down and focus on the user experience to solve any problems.
In response to a query on slate or notebook touch applications, Mendenhall stated that laptops don’t have the screen in an optimal position for touch functions. Han agreed that the form factor of a clamshell is not good for touch. On the other hand, slates are already in one hand so they have the opposite problem of not being well suited for two-handed touch typing. Vincent echoed both positions and observed that no technology exists to address the disparity of having your hands on a keyboard or mouse and being able to have fingers close to the screen
With reference to the broad range of technologies, Mendenhall responded the efforts to develop a new technology requires engineering and devices, but any new technology must be at least 10 times better (faster, lower power, more robust, …) than the technology being displaced. The greatest challenge is to develop a new capability that is capable of supporting legacy functions, at better than the legacy price point.
As touch applications become more commonplace, are they capable of even more advanced functions like security and biometrics? Mendenhall suggested it adds to the number of areas where the tradeoffs are limiting factors. They go to a third party for high resolution applications like fingerprint recognition. Han disagreed and noted that identity information can be embedded in some data. Some applications are in progress for interactive architectures, but not for high resolution functions like fingerprints. Combining touch with other technologies like RFID enables high levels of security. Mozdzyn commented that most touch applications are using a resolution of 1-2 mm, far from the resolution needed for fingerprints.
