Document scanner runs on daylight
A flexible organic based black and white document scanner running on ambient light has been developed by scientists from the University of Tokyo. The scanner has a resolution of 36dpi and a scanner area of 5 by 5 cm.
There are no optical or mechanical parts. Two matrices of organic transistors and photodiodes are patterned on separate plastic films, then laminated together using conductive silver paste. The device works by letting background light through a transparent matrix which is reflected by the images on the document. The reflected light is picked up by the photodiodes, each of which can distinguish between black and white.
The channel regions of the organic field effect transistors are based on a pentacene material, with a polyimide gate dielectric and gold source and drain contacts. The transistor has an electron mobility of 0.7cmsquare/Vs.
The researchers aim that by shrinking the cathode area to 50 by 50 micrometers they can build a 250dpi sensor.