Shuichi Tai

An artificial retina chip made of a 128 x 128 pn-np variable-sensitivity photodetector array

An artificial retina chip is an image detection device that, like biological retinas, can extract essential features directly from projected images. This paper presents an artificial retina chip consisting of a 128/spl times/128 array of pn-np variable-sensitivity photodetectors (VSPDs). This photodetector (PD) utilizes pn junctions and thus avoids the rather inflexible memory effect encountered in our previously reported device, which used Schottky contacts in a metal-semiconductor-metal (MSM) configuration. We introduce a novel filter division method for arbitrary two-dimensional (2-D) filter operation, and successfully employ it in a 2-D edge extraction task.<<ETX>>

A novel model of two-dimensional image associative memory for optical neurochips

A novel type of optical neurochip, which associates complete stored images in response to the incomplete inputs, is presented The original point of this work is that the optical neurochip allows direct image processing in terms of parallel input/output interface and parallel neural processing. So the processing speed of 100 times higher than the conventional neurochips is obtained. The operation principle is based on the nonlinear transformation of the input two-dimensional images to the corresponding one-dimensional vectors. A Hebbian-like learning rule is utilized in order to make the whole system simple. The simulation results verify that the system has very high error-collection and ultra-fast processing capabilities.