ABSTRACT
This study proposes an optical panel with full multitouch using the patterned indium tin oxide (ITO) and an algorithm matrix to avoid ghost points. The patterned ITOs include the virtual high and low impedances. The algorithm matrix with two configurations of equivalent circuits for array scanning is derived using the voltage divider rule. The fabrication process of the multitouch panel is carried out using microelectromechanical systems technology. The optical characteristics of the multitouch panel in the UV, visible, and IR regions are measured using photometric analysis. The multitouch panel, containing sensing pixels of 30×30 arrays, has a pixel size of 2×2 mm2 and a pitch distance of 2 mm. The average values of high and low impedances are 53.23 and 9.3 k Ω, respectively. The maximum transmittance is about 74.2% at the wavelength of 692 nm. The multitouch panel based on high and low impedance patterns has been specifically designed to offer good adjacent touch resolution and sensitivity for reality multitouch applications. In addition, the patterned design and the algorithm matrix provide unlimited multitouch points and avoid ghost points.
ABSTRACT
A novel plastic packaging of a piezoresistive pressure sensor using a patterned ultra-thick photoresist is experimentally and theoretically investigated. Two pressure sensor packages of the sacrifice-replacement and dam-ring type were used in this study. The characteristics of the packaged pressure sensors were investigated by using a finite-element (FE) model and experimental measurements. The results show that the thermal signal drift of the packaged pressure sensor with a small sensing-channel opening or with a thin silicon membrane for the dam-ring approach had a high packaging induced thermal stress, leading to a high temperature coefficient of span (TCO) response of -0.19% span/°C. The results also show that the thermal signal drift of the packaged pressure sensors with a large sensing-channel opening for sacrifice-replacement approach significantly reduced packaging induced thermal stress, and hence a low TCO response of -0.065% span/°C. However, the packaged pressure sensors of both the sacrifice-replacement and dam-ring type still met the specification -0.2% span/°C of the unpackaged pressure sensor. In addition, the size of proposed packages was 4 × 4 × 1.5 mm(3) which was about seven times less than the commercialized packages. With the same packaging requirement, the proposed packaging approaches may provide an adequate solution for use in other open-cavity sensors, such as gas sensors, image sensors, and humidity sensors.
