Hardware engine for real-time pen tracking on electrophoretic displays

Although the electrophoretic display (EPD) has become the main solution to the display of an electronic reader (E-Reader), the latency of displaying a new image on the EPD is much lower than that on liquid crystal displays. This problem leads to poor user experience when a user wants to annotate some important points by supplying with more comments on the EPD. The technical issues that should be dealt with include the pixel interpolation between the plotted pixels and the fast driving waveform design for those interpolated pixels. In this paper, we propose a new hardware engine that performs real-time pixel interpolation to compensate the resolution mismatch between the touch panel and the EPD. In addition, a new fast driving scheme for plotting the interpolated pixels to the black state on the EPD is also proposed. The experimental results show that the engine can complete the pixel interpolation in 2 ms and the pixels will not be overdriven. The overall latency of the pen tracking function is much shorter than that of the previous approaches.