Active-Matrix Organic Light-Emitting Diode (Amoled) is a new display technology for mobile phones, televisions, and everything in between. Currently used on several top Android Smartphones like the Nexus S and Galaxy S II, the market for AMOled displays is expected to more than triple in 2011 to $4.26 billion and grow to $14 billion in 2015, according to research firm DisplaySearch.

Oled (Organic Light-Emitting Diode) refers to the thin film of organic material on top of the display. When electrical current is applied to this film, it gives off light, just like a regular LED – except it’s only a few nanometers thick. Learn more about Oleds on Wikipedia.

AM (Active Matrix) refers to the display is addressed. Each pixel has an active element (a thin-film transistor, or TFT) that actively provides current to the Oled, maintaining that pixel’s brightness while the other pixels are being addressed. Without the active matrix, Oled displays are small and low-resolution, used for applications like mobile phone sub-displays.

Why Amoled?

When today’s LCD displays are such high quality (like Apple’s Retina display), and made in such high volumes, why go to the effort to introduce a new display technology?

Amoled displays are a next-generation technology; they have both higher performance, and lower potential cost than AMLCDs.

Amoleds have higher performance than LCD

  • Image Quality: Richer colors, deeper blacks, and sharper images
  • Thickness: No backlight means they’re thinner and lighter
  • Power: 30-50% less power
  • Response Time: 1000 times faster than LCD, so fast images aren’t blurred
  • Viewing Angle: Widest field of view

Amoleds can be 30-50% lower cost than LCD

  • Fewer components and simpler processing (backlight or color filters)
  • Can use much of the existing LCD infrastructure
  • Compatible with upcoming technologies such as ink jet printing, and roll-to-roll processing


How LCD Displays Work

To understand Oleds and their unique advantages, it’s helpful to understand a bit about LCD displays. We’ll discuss only AMLCD (Active-Matrix Liquid Crystal Display) – the bright, full-color ones found on most mobile phones, tablets, notebook computers, and televisions.

LCD vs OLED Drawings 02 Technology

Cross-section of an AMLCD Display

  • Backlight: a bright source of light, typically LEDs or fluorescent tubes.
  • Liquid crystal and polarizers: these layers work together to block the light or let it through
  • TFT backplane: the circuits in the TFT backplane control the liquid crystal, twisting it to block the light or allow it to pass
  • Color filter: filters the (white) light from the backlight to make the red, green and blue subpixels

Because of the nature of AMLCD displays, they have the following problems:

  • Most of the backlight’s light is lost in the LCD layers; only about 5% of the light makes it through the front of the display
  • The backlight must be on even during dim images, wasting a lot of power.
  • The liquid crystal layer can’t block all the light, so some light leaks through, making the blacks “gray”
  • Because the light comes from the backlight, and has to pass through several layers, the viewing angle can be poor
  • The colors filters are inefficient, so to save power they are often thin, leading to washed-out colors.

How Amoled Displays Work

Amoled displays are inherently simpler and have only two main layers:

LCD vs OLED Drawings 01 Technology

Cross-section of an AMOLED display

  1. An OLED (organic light-emitting diode) layer that emits light.
  2. A backplane, made of TFT (thin-film transistor) circuits that provide current to the OLEDs, thereby controlling their brightness.

There’s usually a polarizer on top, which cuts reflected light. And that’s it! The simpler structure will lead to lower cost than LCDs, in addition to being thinner and lighter.

AMOLEDs also have other advantages:

  • Lower Power: Only those pixels that are lit up consume power; dim screens (such as white text on a black background) consume almost no power, and video (where the pixels are only about 30% on) consumes much less power than LCD.
  • Higher Contrast: When a pixel is off, no light comes out all. This high contrast (over 100,000:1) gives stunning image quality
  • Better Viewing Angle: Because the light comes from the OLEDs on top of the display, the viewing angle is a true 180 degrees with no color shift
  • Richer Colors: The colors of the OLEDs are rich and deep, so the display looks much more vibrant than LCD.

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