Display Technology

Ricoh achieves an environment-friendly, paper-like display by fabricating the transistor circuit using only printing technology.

Display Technology with Printing

"Printable Electronics" is a technology for building up electronic devices by ink-jetting or gravure-printing liquefied metallic and semiconducting materials.
This method is drawing attention as a low-cost processing technology with less environmental impact thanks to its advantages in material efficiency and low temperature process compared with conventional semiconductor processes that need etching on thinned functional materials.

Ricoh applied this technology to fabricating transistor circuits, which control every pixel of a display. Unique technologies such as surface energy control (dividing the surface of a film substrate into hydrophilic and hydrophobic domains, and applying ink on hydrophilic domain), ink formula and ink-jetting control, enabled the microscopic transistor structures to be built up on plastic films. The thin lightweight high-resolution display was achieved using the above technologies.

(a)With surface energy control
(a) With surface energy control

(b)Without surface energy control
(b) Without surface energy control

The trace patterns printed with Ricoh's unique surface energy controlling technology (a) are much more precise than (b), showing no interference fringe (smooth surface).

Fig. 1 Difference in ink-jetted trace patterns

Fig. 2 A display fabricated with the printing technology on film substrate
Fig. 2
A display fabricated with
the printing technology on film
substrate

Fig. 3 A displaying demonstration
Fig. 3
A displaying demonstration

Innovative Technology

We have attained the optimal resolution (200ppi=pixels per inch)as a display driven by transistor circuit whose every components (electrodes, semiconductor, insulator and trace) are fabricated only with printing.

Applications

The low-cost, environment-friendly, high-resolution, lightweight and robust display can be applied to various fields including e-books.

Moreover, the application of printable electronics is not limited in displays. It surely has potential for applications such as sensors and memories. In particular, R&D aiming at applying this technology to RFID tags is active in Europe and other regions.

Ricoh's technology is expected to contribute to the continuing progress of printable electronics.

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