TYPES OF OLEDS:
There
are several types of OLEDs:
Passive-matrix
OLED
Active-matrix
OLED
Transparent
OLED
Top-emitting
OLED
Foldable
OLED
White
OLED
Each
type has different uses. In the following section, we'll discuss
each type of OLED. Let's start with passive-matrix and active-matrix
OLEDs.
Passive-matrix
OLED (PMOLED)
PMOLEDs have strips of cathode, organic layers and strips of anode. The anode strips are arranged perpendicular to the cathode strips. The intersections of the cathode and anode make up the pixels where light is emitted. External circuitry applies current to selected strips of anode and cathode, determining which pixels get turned on and which pixels remain off. Again, the brightness of each pixel is proportional to the amount of applied current.
PMOLEDs have strips of cathode, organic layers and strips of anode. The anode strips are arranged perpendicular to the cathode strips. The intersections of the cathode and anode make up the pixels where light is emitted. External circuitry applies current to selected strips of anode and cathode, determining which pixels get turned on and which pixels remain off. Again, the brightness of each pixel is proportional to the amount of applied current.
PMOLEDs
are easy to make, but they consume more power than other types of
OLED, mainly due to the power needed for the external circuitry.
PMOLEDs are most efficient for text and icons and are best suited for
small screens (2- to 3-inch diagonal) such as those you find in cell
phones, PDAs
and MP3
players. Even with the external circuitry, passive-matrix OLEDs
consume less battery power than the LCDs that currently power these
devices.
Active-matrix
OLED (AMOLED)
AMOLEDs have full layers of cathode, organic molecules and anode, but the anode layer overlays a thin film transistor (TFT) array that forms a matrix. The TFT array itself is the circuitry that determines which pixels get turned on to form an image.
AMOLEDs have full layers of cathode, organic molecules and anode, but the anode layer overlays a thin film transistor (TFT) array that forms a matrix. The TFT array itself is the circuitry that determines which pixels get turned on to form an image.
AMOLEDs
consume less power than PMOLEDs because the TFT array requires less
power than external circuitry, so they are efficient for large
displays. AMOLEDs also have faster refresh rates suitable for video.
The best uses for AMOLEDs are computer monitors, large-screen TVs and
electronic signs or billboards.
Transparent
OLED
Transparent OLEDs have only transparent components (substrate, cathode and anode) and, when turned off, are up to 85 percent as transparent as their substrate. When a transparent OLED display is turned on, it allows light to pass in both directions. A transparent OLED display can be either active- or passive-matrix. This technology can be used for heads-up displays.
Transparent OLEDs have only transparent components (substrate, cathode and anode) and, when turned off, are up to 85 percent as transparent as their substrate. When a transparent OLED display is turned on, it allows light to pass in both directions. A transparent OLED display can be either active- or passive-matrix. This technology can be used for heads-up displays.
Top-emitting
OLED
Top-emitting OLEDs have a substrate that is either opaque or reflective. They are best suited to active-matrix design. Manufacturers may use top-emitting OLED displays in smart cards.
Top-emitting OLEDs have a substrate that is either opaque or reflective. They are best suited to active-matrix design. Manufacturers may use top-emitting OLED displays in smart cards.
Foldable
OLED
Foldable OLEDs have substrates made of very flexible metallic foils or plastics. Foldable OLEDs are very lightweight and durable. Their use in devices such as cell phones and PDAs can reduce breakage, a major cause for return or repair. Potentially, foldable OLED displays can be attached to fabrics to create "smart" clothing, such as outdoor survival clothing with an integrated computer chip, cell phone, GPS receiver and OLED display sewn into it.
Foldable OLEDs have substrates made of very flexible metallic foils or plastics. Foldable OLEDs are very lightweight and durable. Their use in devices such as cell phones and PDAs can reduce breakage, a major cause for return or repair. Potentially, foldable OLED displays can be attached to fabrics to create "smart" clothing, such as outdoor survival clothing with an integrated computer chip, cell phone, GPS receiver and OLED display sewn into it.
White
OLED
White OLEDs emit white light that is brighter, more uniform and more energy efficient than that emitted by HYPERLINK "http://electronics.howstuffworks.com/fluorescent-lamp.htm"fluorescent lights. White OLEDs also have the true-color qualities of HYPERLINK "http://electronics.howstuffworks.com/light-bulb.htm"incandescent lighting. Because OLEDs can be made in large sheets, they can replace fluorescent lights that are currently used in homes and buildings. Their use could potentially reduce energy costs for lighting.
White OLEDs emit white light that is brighter, more uniform and more energy efficient than that emitted by HYPERLINK "http://electronics.howstuffworks.com/fluorescent-lamp.htm"fluorescent lights. White OLEDs also have the true-color qualities of HYPERLINK "http://electronics.howstuffworks.com/light-bulb.htm"incandescent lighting. Because OLEDs can be made in large sheets, they can replace fluorescent lights that are currently used in homes and buildings. Their use could potentially reduce energy costs for lighting.
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