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Revision as of 04:08, 31 August 2010
 | It has been suggested that Super AMOLED be merged into this article. (Discuss) Proposed since June 2010. |
Active-matrix OLED (Active-matrix organic light-emitting diode or AMOLED) is a display technology for use in mobile devices and televisions. OLED describes a specific type of thin 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.[1]
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 generate light upon electrical activation, which functions as a series of switches to control the current flowing to each of the pixels.[2]
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.[3]
Characteristics
Active-matrix OLED displays provide higher refresh rate than their passive-matrix OLED counterparts, and they consume significantly less power.[4] 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. As an example, one commercial QVGA OLED display consumes 3 watts while showing black text on a white background, but only 0.7 watts showing white text on a black background.[5]
Advantages
OLED displays fabricated on flexible plastic substrates[clarification needed] have the following advantages:[6]
- Thin, lightweight and rugged
- Lower-power, superior image quality, and low cost compared to current LCDs
- Rollable display to tuck away when not in use
Disadvantages
- AMOLED displays are prone to material degradation.[clarification needed] However, technology has been invented to circumvent this problem.[7][8][9] Whether these mechanisms have been implemented in current applications of AMOLED displays is unknown, as are potential effects on power consumption.
- AMOLED displays may be difficult to view in direct sunlight. Samsung's Super AMOLED technology addresses this issue by reducing the size of gaps between layers of the screen.
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]
Commercial devices
Phones:
- Nokia N8
- Samsung i7500 Galaxy
- Samsung i9000 Galaxy S
- Google Nexus one
- HTC Desire
- HTC Droid Incredible
- Samsung Rogue
- Samsung Omnia 2
Music Players:
References
- ^ "5-inch or larger OLED panels to become mainstream". Oled-display.net. 2008-11-27. Retrieved 2010-01-25.
- ^ Presentation Introduction to OLED Displays
- ^ 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
- ^ Freudenrich, Craig. "How OLEDs work". HowStuffWorks. Retrieved 30 December 2009.
- ^ Mian Dong; Choi, Y.-S.K; Lin Zhong (2009). "Power modeling of graphical user interfaces on OLED displays". Design Automation Conference, 2009. DAC '09. 46th ACM/IEEE. IEEE: 652–657.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ "Fraunhofer IAP - OLED Research: OLED vs LCD". OLED Research. 2008-11-18. Retrieved 2010-01-25.
- ^ 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
- ^ "Driving apparatus and method for light emitting diode display - US Patent 7352345 Description". Patentstorm.us. 2008-04-01. Retrieved 2010-01-25.