Amorphous Silicon Backplane with Polymer MEMS Structures for Electrophoretic Displays
- PDF / 643,671 Bytes
- 5 Pages / 612 x 792 pts (letter) Page_size
- 105 Downloads / 206 Views
A10.8.1
Amorphous Silicon Backplane with Polymer MEMS Structures for Electrophoretic Displays J.H. Daniel1, a, B.S. Krusor1, N. Chopra2, R.A. Street1, P.M. Kazmaier2, S.E. Ready1, J.H. Ho1 1 Palo Alto Research Center, 3333 Coyote Hill Rd, Palo Alto, CA 94304 2 Xerox Research Centre Canada, 2660 Speakman Dr, Mississauga, Ontario, L5K 2L1 a
[email protected]
ABSTRACT The development of electronic paper has been a long-term goal and electrophoretic displays are a promising candidate for this application. Apart from developing the electrophoretic display medium there are important issues to solve regarding the overall system. The importance of the electronic addressing method increases with the demand for arbitrary images or text. We have developed and tested active-matrix backplanes based on amorphous silicon technology, as well as the driver electronics. The electrophoretic ink is combined with the backplane employing polymer MEMS cell structures. This system allows us to display highresolution images and it is a good test bed for investigating various parameters of the electrophoretic display medium and of the electronics.
INTRODUCTION Electrophoretic displays are promising for electronic paper because of their good visual appearance under various lighting conditions, their low power consumption due to the intrinsic bistability and their suitability for flexible displays [1-6]. The concept of electrophoretic displays is based on electrophoretic ink, which consists of charged white pigments in a dark dyed suspending liquid, for example. Upon application of an electric field the particles move either to the display surface or away from it, depending on the polarity of the charge and on the direction of the electric field. Consequently, a white reflecting or a dark state is achieved. In order to prevent particle agglomeration and particle settling the electrophoretic ink has to be enclosed in cell structures. These structures also serve as a spacer between the two electrode planes of the display. We have employed a MEMS technology that is based on a photopolymer and also micromolding to fabricate the cell walls. In contrast to previously reported microencapsulated electrophoretic displays [2], our approach allows us to vary the cell geometry in order to study the effect on the visual appearance of the display. Furthermore, we are able to test the interaction of the electrophoretic ink with various surface coatings. Apart from the electrophoretic medium, the addressing and the integration into a complete system are important tasks when developing a display. Regarding the backplane of the display, direct addressing is sufficient for relatively simple message boards. However, displaying arbitrary images or text, as required in electronic books or newspapers, demands matrix-addressing. We are developing and testing active-matrix backplanes based on amorphous silicon, together with the driver electronics and driver software. The backplanes are then combined with the electrophoretic display medium. We will show that this co
Data Loading...
