Tokyo University less than 1mm thick film scanner

Film-type image scanners developed by the University of Tokyo’s research team can be bent and the labels on the bottles can be scanned. The magnification of the scanner is 36dpi (the size of each unit is approximately 0.7mm x 0.7mm). Unlike conventional scanners, the thin-film scanner's (bottom) optical sensor is divided into multiple grid-like cells because it can be bent, so it does not harm the books during scanning.

The Department of Engineering, Graduate School of the University of Tokyo published a film-type image scanner using organic TFTs (Thin Film Transistors) and organic optical diodes on December 10, 2004. Made of a thin plastic material and bendable, it can sweep images printed on curved surfaces. The features are ultra-thin and light-weight, and the thickness is less than 1mm, including the packaging film, because it does not require the mechanical device of a conventional scanner.

The scanner was jointly developed by Professor Yoshitani Suguji, an associate professor of the Quantum Electronics Research Center of the Department of Engineering of the University of Tokyo, and a research team led by Sakurai Takahiro, a professor at the University's International Industry and Research Center. The thin-film photosensors and organic TFTs made of organic light-emitting diodes were formed into grids on plastic films, and they were bonded together to make this thin film scanner. The resolution is 36dpi and the size is 5-8cm2.

The scanner is a thin film type and "almost all of the electrodes except the metal electrode are transparent" (dyeing) and can transmit light. When the scanner is placed on a paper or label printed with a black-and-white pattern, reflections through the printing surface through the film-type light are incident on the light sensor. The reading of the pattern can be accomplished by converting incident light into electrical signals. In addition to products with a resolution of 36 dpi, products with a resolution of 250 dpi and no organic TFTs using only light sensors have been developed. After wiring on a product with a resolution of 250 dpi, the letter "T" of size 1 mm x 1 mm was successfully read in the alphabet. For the sensitivity of the light sensor, “the brightness at a distance of a few centimeters from the fluorescent light can be used normally” (dyeing). Regarding related technology patents, Sakurai said: "I hope to obtain circuit patents, manufacturing methods and application software and many other patents."

In organic TFT semiconductors, pentacene (Pentacene) with a high carrier mobility in P-type semiconductors is used. Organic photodiodes, on the other hand, use "blue-pigment-based P-type and N-type organic semiconductors" (stained-grains), and are composed of P-type and N-type semiconductors in the same way as existing photodiodes. The above three kinds of organic materials are all low molecular materials, and a thin film is formed on the plastic film by vacuum evaporation. Plastic materials "like 'PET (polyethylene terephthalate)', is a resin with heat resistance" (stained grain).

Sakura and Sakurai’s research team adopted organic materials in semiconductors because: (1) they can make organic materials bendable (2) they can be made by printing techniques, and (3) they are very costly to produce in large areas. Sugoku said: “We have confirmed that the film types made of organic TFTs can still work normally with a bend radius of 5mm.” In terms of cost, Sakurai said: “The price of a 10cm silicon wafer is about 100,000 yen (approximately Around RMB 7,700), the size of the scanner is 10cm2, and the price should be less than 1,000 yen (approximately RMB 77). However, the current major problem of this product is the short working life. "The product developed this time will degrade in air for about one week. If the packaging technology developed for organic EL is used, its performance should be maintained for several months."

In the International Circuit Technology Conference "ISSCC 2004" held in February 2004, Sugiya and Sakurai announced the "artificial skin" made by pasting grid-like pressure sensors and organic TFTs on plastic films. In addition, the results will also be held at the International Conference on Semiconductor Components held in San Francisco, USA, from December 13th to 15th, 2004. The IEEE International Electron Devices Meeting (IEDM 2004) will be held in San Francisco in February 2005. Presented at the conference "ISSCC 2005".