MED (2002-06)

Title: Next generation OLED-on-silicon microdisplays
Research Engineer: Graeme Kelly
Sponsor: MicroEmissive Displays Ltd
Academic Supervision: Prof Tughrul Arslan, University of Edinburgh

• An overview of Organic Light-Emitting Diode (OLED) technology, and also of microdisplay technology, relevant to the body of work is presented.
• The conclusions of the investigation of the original research project proposed by MicroEmissive Displays, namely to investigate the feasibility of employing SoC technologies on OLED-on-Silicon microdisplays are presented. A SoC platform suitable for OLED-on-Silicon microdisplays is also proposed.
• The redefinition of the research project which arose from this SoC-technology investigation is also presented. In simple terms, the research project was expanded to cover "the exploration of technologies leading towards next generation OLED-on-Silicon Microdisplays'', in addition to the investigation of SoC technologies.
• This exploration covered two additional areas: namely, drive-circuit and image-processing technologies which could make a significant contribution to a display's performance without incurring prohibitive costs.
  • A high-level review of existing electronic drive schemes (i.e. OLED-display pixel drive circuits (CMOS)) was performed. Evaluation of these drive schemes was also performed, ultimately leading to a recommendation of a drive circuit for MicroEmissive Displays to use in their next generation display and also to a proposed redefinition of the industry standard definition of display lifetime.
  • Limitations of this recommended drive circuit are also identified/acknowledged, indicating why the proposed circuit will not be an ideal long term option (despite the fact that it was concluded to be the best option at the time of the recommendation). The work goes on to propose alternative drive circuits that may provide longer term solutions i.e. circuits that warrant further investigation (e.g. circuits that are worthy of consideration for implementation on a piece of test silicon). These longer term solutions were ultimately considered interim solutions as a simple-to-implement long-term solution, which was reliant on expected improvements in the chemistry of OLED materials, was also identified.
  • Algorithmic approaches to overcoming some common drive circuit/OLED material limitations are also reviewed/proposed.
  • Finally, image processing/optimisation techniques were considered as an alternative route to improving display performance. Again, recommendations are made to MicroEmissive Displays regarding which of the current technologies best suits their application: extensions of these techniques are also proposed.
    

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