David A. Fish

38.1: Optical Feedback for AMOLED Display Compensation using LTPS and a-Si:H Technologies

New optical feedback pixel circuits for a-Si:H and LTPS technologies will be presented. The circuits will enable correction of threshold voltage drift of the drive TFT and degradation of the OLED. In the a-Si:H case this will be achieved with a standard a-Si:H process and for LTPS an a-Si NIP photodiode is integrated. Operation, technology and measurements will be presented.

32.1: Invited Paper: A Comparison of Pixel Circuits for Active Matrix Polymer/Organic LED Displays

In this paper measurements on several types of active matrix polymer LED (AMPLED) displays will be presented. The issues ofimage uniformity and polymer aging will be addressed by pixel circuit designs.

Towards large‐area full‐color active‐matrix printed polymer OLED television

Abstract— We have developed a new multi-head polymer OLED ink-jet-printing technology to make large-screen OLED television displays. This printer is used to make a 13-in.-diagonal 16:9-format polymer-OLED prototype driven by an LTPS active matrix with a pixel circuit which compensates for TFT threshold-voltage variations. A novel scrolling-bar addressing scheme is used to reduce motion artifacts and to make sparkling images with a high local peak brightness. The scalability of the polymer-OLED technology to larger sizes for television applications is discussed.

44.4: Distinguished Paper: Towards Large‐Area Full‐Color Active‐Matrix Printed Polymer OLED Television

We have developed a new multi-head Polymer OLED inkjet print technology to make large screen OLED television. This printer is used to make a 13″ diagonal 16:9 format Polymer OLED prototype driven by an LTPS active matrix with a pixel circuit which compensates for TFT threshold voltage variations. A novel scrolling-bar addressing scheme is used to make sparkling images with a high local peak brightness. Color processing is used to improve the overall perception of the image.

Improved optical feedback for OLED differential ageing correction

— To compete with LCDs and to meet standard display product specifications, OLED displays must have a high degree of tolerance to differential ageing or “burn-in.” A new optical feedback pixel circuit is presented that enables accurate differential ageing correction, can have low power consumption, and enables a high degree of non-uniformity correction. The circuit can be implemented in LTPS, and a-Si:H TFT technologies and circuits for both cases are shown. The a-Si:H approach is low cost and enables correction of both TFT threshold voltage drift and OLED degradation at the same time. The circuit analysis, operation, and technology will be described and results presented.

35.2: Improved Optical Feedback for AMOLED Display Differential Ageing Compensation

A new optical feedback pixel circuit is presented that enables a high degree of differential ageing correction, has low power consumption compared to standard AMOLED pixel circuits and enables a high degree of non-uniformity correction. The circuit operation and the technology used to construct it will be described and results presented.

Advanced poly-LED displays

Philips have been actively developing polymer OLED (poly-LED) displays as a future display technology. Their emissive nature leads to a very attractive visual appearance, with wide viewing angle, high brightness and fast response speed. Whilst the first generation of poly-LED displays are likely to be passive-matrix driven, power reduction and resolution increase will lead to the use of active-matrix poly-LED displays. Philips Research have designed, fabricated and characterized five different designs of active-matrix polymer-LED display. Each of the five displays makes use of a distinct pixel programming- or pixel drive-technique, including current programming, threshold voltage measurement and photodiode feedback. It will be shown that hte simplest voltage-programmed current-source pixel suffers from potentially unacceptable brightness non-uniformity, and that advanced pixel circuits can provide a solution to this. Optical-feedback pixel circuits will be discussed, showing that they can be used to improve uniformity and compensate for image burn-in due to polymer-LED material degradation, improving display lifetime. Philips research has also been active in developing technologies required to implement poly-LED displays on flexible substrates, including materials, processing and testing methods. The fabrication of flexible passive-matrix poly-LED displays will be presented, as well as the ongoing work to assess the suitability of processing flexible next-generation poly-LED displays.

33.4: A Novel LTPS Application: A Multiplexed Thermal Array for DNA Amplification

We describe a multiplexed TFT array for the temperature controlled thermal cycling required for DNA amplification. LTPS is an ideal technology to enable the accurate and uniform temperature profiles required for assays used in a range of medical conditions as it enables high parallelism at low cost for rapid diagnosis. We will present the application background, the design, fabrication and testing of our LTPS thermal cycler.

New applications for LTPS array technology including lab‐on‐chip and MEMS actuators

— The use of low-temperature poly-Si technology for new applications beyond displays is presented. These applications include lab-on-chip, MEMS actuators, and sensors. As a key example, the use of high-voltage poly-Si TFTs for rapid heating and temperature control, as is required for DNA amplification within lab-on-chip, is described in detail. Other examples given include MEMS ink-jet printer heads and the formation of photosensors and impedance sensors for optical and electronic input, which can be used not only in displays and lab-on-chip, but also for new applications such as fingerprint sensing and particle counting.