AMOLED (active-matrix organic light-emitting diode) is a display technology for use in mobile devices and televisions. OLED describes a specific type of thin-film-display technology in which organic compounds form the electroluminescent material, and active matrix refers to the technology behind the addressing of pixels.
As of 2012[update], AMOLED technology is used in mobile phones, media players and digital cameras, and continues to make progress toward low-power, low-cost and large-size (for example, 40-inch) applications.
An AMOLED display consists of an active matrix of OLED pixels that generate light (luminescence) upon electrical activation that have been deposited or integrated onto a thin-film-transistor (TFT) array, which functions as a series of switches to control the current flowing to each individual pixel.
Typically, this continuous current flow is controlled by at least two TFTs at each pixel (to trigger the luminescence), with one TFT 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, thereby eliminating the need for the very high currents required for passive-matrix OLED operation.
TFT backplane technology is crucial in the fabrication of AMOLED displays. The two primary TFT backplane technologies, namely polycrystalline silicon (poly-Si) and amorphous silicon (a-Si), are used today in AMOLEDs. These technologies offer the potential for fabricating the active-matrix backplanes at low temperatures (below 150°C) directly onto flexible plastic substrates for producing flexible AMOLED displays.
Manufacturers have developed in-cell touch panels, integrating the production of capacitive sensor arrays in the AMOLED module fabrication process. In-cell sensor AMOLED fabricators include AU Optronics and Samsung. Samsung has marketed their version of this technology as Super AMOLED. Researchers at DuPont used computational fluid dynamics (CFD) software to optimize coating processes for a new solution-coated AMOLED display technology that is cost and performance competitive with existing chemical vapor deposition (CVD) technology. Using custom modeling and analytical approaches, they developed short- and long-range film-thickness control and uniformity that is commercially viable at large glass sizes.
Comparison to other technologies
AMOLED displays provide higher refresh rates than their passive-matrix OLED counterparts,[not specific enough to verify] improving response time often to under a millisecond, and 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 colour and brightness shown. As an example, one commercial QVGA OLED display consumes 0.3 watts while showing white text on a black background, but more than 0.7 watts showing black text on a white background, while an LCD may consume only a constant 0.35 watts regardless of what is being shown on screen. Because the black pixels actually turn off, AMOLED also has contrast ratios that are significantly better than LCD.
AMOLED displays may be difficult to view in direct sunlight compared with LCDs because of their reduced maximum brightness. Samsung's Super AMOLED technology addresses this issue by reducing the size of gaps between layers of the screen. Additionally, PenTile technology is often used to allow for a higher resolution display while requiring fewer subpixels than would otherwise be needed, often resulting in a display less sharp and more grainy compared with a non-pentile display with the same resolution.
The organic materials used in AMOLED displays are very prone to degradation over a relatively short period of time, resulting in color shifts as one color fades faster than another, image persistence, or burn-in.
Current demand for AMOLED screens is high, and, due to supply shortages of the Samsung-produced displays, certain models of HTC smartphones have been changed to use next-generation LCD displays from the Samsung and Sony joint-venture SLCD in the future.
Flagship smartphones sold as of 2011-12 use either Super AMOLED or IPS panel premium LCD. Super AMOLED displays, such as the one on the Galaxy Nexus and Samsung Galaxy S III have often been compared to IPS panel premium LCDs, found in the iPhone 4S, HTC One X, and Nexus 4. For example, according to ABI Research the AMOLED display found in the Motorola Moto X draws just 92mA during bright conditions and 68mA while dim.
Super AMOLED is Samsung's term for an AMOLED display with an integrated digitizer, meaning that the layer that detects touch is integrated into the screen, rather than overlaid on top of it. According to Samsung, Super AMOLED reflects 5 times less sunlight compared to the first generation AMOLED. The display technology itself is not changed. Super AMOLED is part of the Pentile Matrix Family. It is sometimes abbreviated SAMOLED.
For the Samsung Galaxy S III, which reverted to Super AMOLED instead of the pixelation-free conventional RGB (non-PenTile) Super AMOLED Plus of its predecessor Samsung Galaxy S II, the S III's larger screen size encourages users to hold the phone further from their face to obscure the PenTile effect.
Super AMOLED Advanced
Super AMOLED Advanced is a term marketed by Motorola to describe a brighter display than Super AMOLED screens, but also a higher resolution – qHD or 960 × 540 for Super AMOLED Advanced compared to WVGA or 800 × 480 for Super AMOLED. This display equips the Motorola Droid RAZR.
Super AMOLED Plus
Super AMOLED Plus, first introduced with the Samsung Galaxy S II and Samsung Droid Charge smartphones, is a branding from Samsung where the PenTile RGBG pixel matrix (2 subpixels) used in Super AMOLED displays has been replaced with a traditional RGB RGB (3 subpixels) arrangement typically used in LCD displays. This variant of AMOLED is brighter and therefore more energy efficient than Super AMOLED displays and produces a sharper, less grainy image because of the increased number of subpixels. In comparison to AMOLED and Super AMOLED displays, the Super AMOLED Plus displays are even more energy efficient and brighter. However, Samsung cited screen life and costs by not using Plus on the Galaxy S II's successor, the Samsung Galaxy S III.
HD Super AMOLED
HD Super AMOLED is a branding from Samsung for an HD-resolution (>1280×720) Super AMOLED display. The first device to use it was the Samsung Galaxy Note. The Galaxy Nexus and the Galaxy S III both implement the HD Super AMOLED with a PenTile RGBG-matrix (2 subpixels/pixel), while the Galaxy Note II uses an RBG matrix (3 subpixels/pixel) but not in the standard 3 stripe arrangement.
HD Super AMOLED Plus
A variant of the Samsung Galaxy S3 using Tizen OS 1 was benchmarked using a non-pentile HD Super AMOLED Plus screen in 2012.
Full HD Super AMOLED
As featured on the Samsung Galaxy S4 and Samsung Galaxy Note 3. It has the broadest color gamut of any mobile display of up to 97% of the Adobe RGB color space, hence making it a wide-gamut display.
Future displays exhibited from 2011 to 2013 by Samsung have shown flexible, 3D, unbreakable, transparent Super AMOLED Plus displays using very high resolutions and in varying sizes for phones. These unreleased prototypes use a polymer as a substrate removing the need for glass cover, a metal backing, and touch matrix, combining them into one integrated layer.
So far, Samsung plans on branding the newer displays as Youm.
Also planned for the future are 3D stereoscopic displays that use eye tracking (via stereoscopic front-facing cameras) to provide full resolution 3D visuals.
Below is a mapping table of marketing terms versus. resolutions and sub-pixel types. Note how the pixel density relates to choices of sub-pixel type.
|Term||Resolution||Size (inches)||PPI||Pixel Layout||Used in|
|AMOLED Capacitive Touchscreen||640×360||3.2||229||RGBG PenTile||Nokia C6-01|
|Super AMOLED||800×480||4.0||233||RGBG PenTile||Samsung Galaxy S|
|Super AMOLED Advanced||960×540||4.3||256||RGBG PenTile||Motorola Droid RAZR|
|qHD Super AMOLED||960×540||4.3||256||RGB S-Stripe||Samsung Galaxy S4 Mini|
|Super AMOLED Plus||800×480||4.3 (4.27)||218||RGB stripe||Samsung Galaxy S II|
|HD Super AMOLED||1280×800||5.3 (5.29)||285||RGBG PenTile||Samsung Galaxy Note|
|HD Super AMOLED||1280×720||5.0||295||RGB S-Stripe||Blackberry Z30|
|HD Super AMOLED||1280×720||4.7 (4.65)||316||RGBG PenTile||Samsung Galaxy Nexus|
|HD Super AMOLED||1280×720||4.7 (4.65)||316||RGB S-Stripe||Motorola Moto X|
|HD Super AMOLED||1280×720||4.8||306||RGBG PenTile||Samsung Galaxy S III|
|HD Super AMOLED||1280×720||5.6 (5.55)||267||RGB S-Stripe||Samsung Galaxy Note II|
|HD Super AMOLED Plus||1280×800||7.7||197||RGB stripe||Samsung Galaxy Tab 7.7|
|Full HD Super AMOLED||1920×1080||5.0||441||RGBG PenTile||Samsung Galaxy S4|
|Full HD Super AMOLED||1920×1080||5.7||388||RGBG PenTile||Samsung Galaxy Note 3|
|This section does not cite any references or sources. (November 2011)|
Commercial devices using AMOLED include:
- BlackBerry Q10
- BlackBerry Z30 (HD Super AMOLED)
- Micromax a90s
- Micromax a90
- BenQ-Siemens S88
- Dell Venue Pro
- HTC Desire (early models)
- HTC Droid Incredible
- HTC Legend
- HTC One S (Super AMOLED Advanced)
- LG Franklin Phone
- LG E-730
- Micromax Superfone Pixel A90
- Motorola Moto X (HD Super AMOLED)
- Motorola Droid RAZR HD and RAZR MAXX HD
- Motorola Droid RAZR (Super AMOLED Advanced)
- Motorola Droid RAZR MAXX (Super AMOLED Advanced)
- Google Nexus One (Early models)
- Google Nexus S (Super AMOLED)
- Google Galaxy Nexus (HD Super AMOLED)
- Nokia 700 (CBD)
- Nokia 808 Pureview (CBD)
- Nokia C7-00
- Nokia C6-01 (CBD)
- Nokia E7-00 (CBD)
- Nokia Lumia 800 (CBD)
- Nokia Lumia 810 (CBD)
- Nokia Lumia 820 (CBD)
- Nokia Lumia 822 (CBD)
- Nokia Lumia 900 (CBD)
- Nokia Lumia 925 (CBD)
- Nokia Lumia 928 (CBD)
- Nokia Lumia 1020 (CBD)
- Nokia N8
- Nokia N9 (CBD)
- Nokia X7
- Pantech Burst
- QMobile Noir Z3
- Samsung ATIV S (HD Super AMOLED)
- Samsung AMOLED Beam SPH-W9600
- Samsung i7500 Galaxy
- Samsung Haptic Beam SPH-W7900
- Samsung SPH-m900 Moment
- Samsung i8910
- Samsung Jet
- Samsung Omnia 2
- Samsung Impression
- Samsung Rogue
- Samsung Transform
- Samsung Galaxy Note (HD Super AMOLED)
- Samsung Galaxy Note II (HD Super AMOLED)
- Samsung Galaxy Note 3 (Full HD Super AMOLED)
- Samsung Galaxy S (Super AMOLED)
- Samsung Galaxy S Advance (Super AMOLED)
- Samsung Galaxy Express (Super AMOLED Plus)
- Samsung Galaxy S II (Super AMOLED Plus)
- Samsung Galaxy S II Plus (Super AMOLED Plus)
- Samsung Galaxy S III (HD Super AMOLED)
- Samsung Galaxy S III Mini (Super AMOLED)
- Samsung Galaxy S4 (Full HD Super AMOLED)
- Samsung Galaxy S4 Mini (qHD Super AMOLED)
- Samsung Galaxy S4 zoom (qHD Super AMOLED)
- Samsung Galaxy S Plus (Super AMOLED)
- Samsung Galaxy S Blaze 4G (Super AMOLED)
- Samsung Galaxy S5 (Full HD Super AMOLED)
- Samsung Galaxy Nexus (HD Super AMOLED)
- Samsung Galaxy Gear (Super AMOLED)
- Samsung Droid Charge (Super AMOLED Plus)
- Samsung Wave S8500 (Super AMOLED)
- Samsung S8600 Wave III (Super AMOLED)
- Samsung Focus (Super AMOLED)
- Samsung Focus S (Super AMOLED Plus)
- Samsung Focus 2 (Super AMOLED)
- Samsung Omnia 7 (Super AMOLED)
- Samsung Omnia W (Super AMOLED)
- Samsung Omnia M (Super AMOLED)
- Samsung Infuse 4G (SGH-i997) (Super AMOLED Plus)
- Vertu Signature S
- ZTE Blade (Initial Models)
- Portable music players
- Games consoles
- Music production hardware
- Digital cameras
- Olympus XZ-1
- Samsung EX1
- Samsung EX2F
- Samsung NX10
- Samsung NX11
- Samsung NX20
- Samsung NX100
- Samsung NX200
- Samsung NX210
- Samsung NX300
- Samsung NX1000
- Samsung NX1100
- Samsung NX2000
- Samsung WB2000
- Samsung WB650
- Lee, Hyunkoo; Park, Insun; Kwak, Jeonghun; Yoon, Do Y.; Kallmann, Changhee Lee (2010). "Improvement of electron injection in inverted bottom-emission blue phosphorescent organic light emitting diodes using zinc oxide nanoparticles". Applied Physics Letters 96: 153306. doi:10.1063/1.3400224.
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