Muneaki Yamaguchi

Two-Dimensional Contact-Type Image Sensor Using Amorphous Silicon Photo-Transistor

We propose a novel two-dimensional contact-type image sensor using amorphous silicon photo-transistors (APTs) in order to form a compact image scanner. Each pixel of the sensor consists of an APT, a storage capacitor, and an amorphous silicon thin-film transistor (a-Si TFT). We have made a prototype 140×240-pixel sensor with a pixel size of 160 µm square. It is confirmed that the prototype APT sensor can detect an image under room light. Exposure for gray scale images is in the range of 10-1 to 7 lxs. This TFT-switched, two-dimensional contact-type image sensor is promising for large-area applications because the process for APTs is fully compatible with that for conventional a-Si TFTs.

H.264/AVC improvement based on adaptive motion vector coding

We propose a new method for improving motion vector coding. The coding efficiency of the H.264/AVC standard is significantly degraded for video sequences that include irregular motions. The degradation is caused by the fact that the correlations among the motion vectors on adjacent blocks get to be small when motions are irregular. Our method solves this problem by two schemes. First, the predictive motion vector (PMV) is adaptively coded with additional bits based on the distribution pattern of reference vectors. Second, an appropriate code table for the motion vector difference (MVD) is adaptively selected out of a couple of tables defined in advance. These schemes enable the appropriate methodologies for the motion vector coding to be adaptively selected according to the motion vector diversity. Experimental results show the effectiveness and potentiality of our approach for high coding efficiency.

Foldable-display systems as a standard platform for multimedia use

A prototype of a foldable-display system (FDS) that uses two active-matrix liquid crystal displays (LCDs) has been developed. The display images can be inverted and an automatic viewing-angle-control function lets users on both sides of the FDS see the image clearly. By using the FDS as a face-to-face communicator, the authors demonstrate its potential as a standard multimedia platform.