Apple’s U.S. Patent No. 8,603,574 for a “Curved touch sensor” details a manufacturing technique that produces accurate, curved touch surfaces without deficiencies caused by substrate warping or deformation. The patent’s claims specifically cover use of the technology in displays, touch pads and touch mice, among other devices. Apple notes that current touch panel technologies, specifically stackups containing thin-film conductors, are difficult to work with due to a “desired thinness of the substrate and thin film.” For example, when depositing thin films over a flexible substrates like plastic, the annealing, or heating, temperature must be kept relatively low to avoid structural damage. Manufacturers, however, may prefer to employ high annealing temperatures for added thin film resistiveness and enhanced optical properties.
