Apple patents reveal what's behind the touchscreen

Germany's Balda supplied module by way of Taiwanese partner Nicolas Mokhoff EE Times (07/09/2007 9:00 AM EDT) All public teardowns have identified Balda, which produces high-tech assemblies from high-performance plastics and electronic components at its headquarters in Bad Oeynhausen, Germany, as the supplier of the touchscreen display module for the iPhone. But a closer look reveals that Balda's Taiwan-based partner, TPK Holding, with which Balda formed a joint venture to get into touchscreen production, is really behind the module. The touchscreen display itself is being supplied by multiple sources: Epson, Sharp, Toshiba and Matsushita Display Technology Co. Ltd., according to market watcher iSuppli. The research firm estimates that the display module costs $27, which represents 10.8 percent of the 8-Gbyte iPhone model's cost, and that the touchscreen display adds $24.50, representing 9.8 percent of the 8-Gbyte version's cost. "The real breakthrough here, displaywise, is Apple's use of multitouch technology using a projective capacitive design," said Paul Semenza, vice president for displays at iSuppli Corp. "What we suspect they did was to use an algorithm within NXP's ARM-based controller chip to measure the finger touches over the display and adjust the screen content accordingly." Apple was assigned patent application number 20060097991 for the multitouch screen technology--one of some 200 iPhone-related patents for which Apple applied. The abstract reads in part that the touch panel has "a transparent capacitive sensing medium configured to detect multiple touches or near touches that occur at the same time and at distinct locations in the plane of the touch panel and that produces distinct signals representative of the location of the touches on the plane of the touch panel for each of the multiple touches." What sets the technology apart is that other technologies, such as resistive, capacitive, infrared, surface acoustic wave, electromagnetic and near-field imaging, are unable to distinguish touch positions accurately when more than one object, such as a finger or stylus, at a time is placed on the panel. Intuiting user's intentions In a review of Apple's patents for the iPhone, the Web site Unwired View claims Apple solved the accuracy problem by putting a number of transparent electrodes on a grid to determine the positions of multiple objects touching the screen at the same time. A force-sensing mechanism embedded between the electrode layers allows the user's intentions to be deduced based on the way the user places a finger or fingers on the screen, with accidental touches filtered out. That results in easy scrolling, page flipping and image-size changes via natural movement of one or several fingers, according to Unwired View. A complementary patent describes "multifinger gestures," covering all the ways Apple could think of to manipulate various objects that appear on the screen, such as rotating, zooming, panning, scrolling and flipping. A patent for a "multifunctional handheld device" covers every aspect of the iPhone user interface, describing a full-screen touchscreen display covering almost all of the surface area of the handheld device and operated mainly through on-screen buttons. The touchscreen uses software-controlled screen buttons enabling the functions of an iPod, cell phone and Internet browser in one device. When the user simultaneously touches two or more device icons, the device activates the multiple device functionalities and brings the appropriate graphical user interfaces into view on the screen. The elegant iPhone system design marries a microelectromechanical-system accelerometer-based motion sensor to the controller, which in turn translates the touchscreen activity into electrical signals. "Overall, Apple was able to go for ruggedness by eliminating a sheet of plastic inside the touchscreen and, we think, combining the sensors on the top isolation sheet. That way, they can assure that the touchscreen eliminates the scratches usually found with other touchscreen devices," said Semenza of iSuppli. "They have excelled at the system design of the portable device."