Feedback circuit for organic LED active-matrix display drivers

A feedback circuit for an Organic Light Emitting Diode (OLED) based display is proposed and demonstrated. An OLED-based flat panel display is brighter, much lower power, has no viewing angle limitation and potentially cheaper compared to available Liquid Crystal (LC) based displays. Despite these advantages, an OLED-based display is not widely commercialized mainly due to its short practical lifetime. The I-V characteristics of the individual OLED pixels vary over time, temperature and processing-dependent parameters. Moreover, the variation is not uniform across an array of OLED pixels, causing OLED based displays to lose brightness accuracy after a few thousand hours of operation. The proposed feedback circuit is used to compensate for the non-uniformities in the individual OLED characteristics. The resulting display leverages the beneficial aspects of OLED display technology, while maintaining pixel uniformity and grayscale reproducibility. A demonstration system is built proving the feasibility of a flat panel display using direct optical feedback. The feedback loop monitors the output light level using a sensor and adjusts the current fed to the pixels to set the output light power to a digitally set reference level. The system shares a single feedback loop among a number of pixels, saving power and real estate. The demonstration system consists of a 5x5 array of LEDs, a CMOS camera, analog pixel circuitry, driver and feedback loop, as well as a digital controller. The demonstration system also shows the feasibility of time-sharing a feedback loop among a number of output devices.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2002

Author dc:creator

• Lisuwandi, Eko T., 1977-

Advisor dc:contributor.advisor

• Charles G. Sodini and Vladimir Bulovic.

• Electrical Engineering and Computer Science.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/16849

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/16849