AMOLED (active-matrix organic light-emitting diode) is an emerging display technology for use in mobile devices such as mobile phones. OLED describes a specific type of ultra thin, ultra bright display technology which doesn't require a backlight and Active-Matrix refers to the technology behind the addressing of pixels. AMOLED technology continues to make progress towards low-power and low-cost large size (e.g. 40-inch) for applications such as TV.
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Technical explanation
An active-matrix OLED (AMOLED) display consists of OLED pixels that have been deposited or integrated onto a thin film transistor (TFT) array to form a matrix of pixels that illuminate light upon electrical activation, which functions as a series of switches to control the current flowing to each of the pixels.[citation needed]
Typically, this continuous current flow is controlled by at least two TFTs at each pixel, one to start and stop the charging of a storage capacitor and the second to provide a voltage source at the level needed to create a constant current to the pixel and eliminating need for the very high currents required for passive OLED matrix operation.[1]
Characteristics
Active-matrix OLED displays provide the same video-rate performance[specify] as their passive-matrix OLED counterparts, but they consume significantly less power. This advantage makes active-matrix OLEDs well suited for portable electronics, where power consumption is critical to battery life. The amount of power the display consumes varies significantly depending on the color and brightness shown. "For example, our measurement shows that a commercial QVGA OLED display consumes 3 and 0.7 Watts showing black text on a white background and white text on a black background, respectively."[2]
When the display gets bent with a radius smaller than the critical radius, it leads to cracking of the overcoat layer on the plastic substrate, and this crack propagates through the address bus lines. The cracked bus structures cause the displays to exhibit intermittent line failures, gross line failures, or large regions of non-functioning areas including complete display failure.[citation needed]
Advantages
AMOLED displays fabricated on flexible plastic substrates have the following advantages:[3]
- Very thin and lighter weight
- Greatly minimized propensity for breakage
- Lower-power, highly rugged with superior image quality, and low cost compared to the current LCD's
- Due to their inherent ruggedness, allow a unique form factor of conformability and rollability during use, transportation and storage.
Display material degradation
AMOLED displays are prone to material degradation. However technology has been invented to circumvent this problem.[4][5][6]
Whether these mechanisms have been implemented in current applications of AM OLED displays and their effect on power consumption are unknown.
Active matrix element: TFT backplane technology
TFT backplane technology is a crucial enabler for the fabrication of flexible AM OLED displays.
Two primary TFT backplane technologies (poly-Silicon (poly-Si) and amorphous-Silicon (a-Si)) are used today in AMOLEDs. These technologies offer the potential for fabricating the required active matrix backplanes at low temperatures (< 150°C) directly on the flexible plastic substrate for producing flexible AM OLED displays.[citation needed]
References
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This article includes a list of references, related reading or external links, but its sources remain unclear because it lacks inline citations. Please improve this article by introducing more precise citations where appropriate. (June 2009) |
- ^ TFT circuit A Novel LTPS-TFT Pixel Circuit Compensating for TFT Threshold-Voltage Shift and OLED Degradation for AMOLED, Department of Electrical Engineering, National Cheng Kung University
- ^ Mian Dong; Choi, Y.-S.K; Lin Zhong (July 2009). "Power modeling of graphical user interfaces on OLED displays". Design Automation Conference, 2009. DAC '09. 46th ACM/IEEE (IEEE): 652-657.
- ^ Fraunhofer IAP - OLED Research: OLED vs LCD
- ^ http://ieeexplore.ieee.org/Xplore/login.jsp?url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F4054018%2F4054019%2F04054244.pdf%3Farnumber%3D4054244&authDecision=-203
- ^ http://ieeexplore.ieee.org/Xplore/login.jsp?url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F9425%2F4114308%2F04114309.pdf%3Farnumber%3D4114309&authDecision=-203
- ^ http://www.patentstorm.us/patents/7352345/description.html
External links
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