This Small Business Innovation Research (SBIR) Phase I project will address the core hardware and software issues necessary to yield a fully functioning multi-touch pressure-sensing screen by putting an Interpolating Force-Sensitive Resistance (IFSR) based sensor behind an electronic paper display. IFSR has significant advantages over other currently-available multi-touch solutions. These include low cost, low power consumption, native multi-touch capacity, the ability to sense touches from any object or stylus, flexibility and form-factor scalability. Because of its flat form factor and pressure sensing ability, an IFSR sensor can be mounted behind a thin, flat display, providing a commercially viable multi-touch input solution for large and small e-ink based devices. The research for this project includes five components: 1) layering and integration of an e-ink display, IFSR sensor, and circuit board; 2) custom design of a fully-integrated single sensor driver chip to replace the current analog multiplexer, two shift registers, and two buffers; 3) development and implementation of an efficient sensor scanning algorithm to enable micro-Ampere power consumption; 4) research and testing of CPU-efficient techniques for real-time identification of functional touches by fingers or styli, and rejection of palms and other non-functional touches.
This innovation directly addresses the challenges faced by existing multi-touch solutions when applied to electronic paper displays, including cost, power consumption, ability to sense both fingers and styli, and the lack of backlighting, which hinders above-screen sensing technologies. If successful, the resulting design and techniques will fill the technical gap that denies multi-touch input from the large existing market of e-book reader devices. Since the results can easily be generalized to devices with other types of flexible displays (notably OLED screens) they have the potential to open up a whole new market space for thin, affordable, multi-touch input displays benefiting retail, commercial, industrial, and public-sector end users.
