BYTE.com > Features > 2006
Powering Passive OLED Displays in Handhelds
By Joon Park
December 25, 2006
(Powering Passive OLED Displays in Handhelds
: Page 1 of 1 )
Organic light-emitting diodes are an emerging technology that is set to revolutionize displays, offering a number of advantages over LCDs. These include ease of manufacture, faster response time, wider viewing angles, lower power consumption and brighter/ higher-contrast images. Moreover, OLEDs are self-emissive, requiring no backlight. This not only saves power but creates 1mm-thick displays.
Similar to LCDs, OLED displays come in both passive-matrix and active-matrix configurations. With passive matrix, the display is connected as a grid of diodes, each diode comprising an individual OLED pixel. The rows of the grid are lit one at a time using external drive circuitry.
In contrast, active-matrix displays include transistors within the display that enable pixels to be continuously illuminated. However, unlike LCDs, OLEDs are current-driven. This adds to the complexity of active-matrix design, thus boosting the popularity of passive matrix designs. These PMOLEDs are used in various applications including cellphones, car stereos, MP3 players and other consumer products.
Power Up
Because many OLED displays today are used in portable applications, power consumption is extremely important. Any power IC must be designed to operate with the highest efficiencies and to conserve as much power as possible to maximize battery life, especially when the display is not operating.
The power requirement for OLED displays depends on several factors. As the display is current-driven, the peak-current requirement is dependent on the total number of pixels that need to be illuminated at one time and the maximum current with which they can be driven.
Additional current is also consumed by the display drive electronics. The voltage required depends on the forward drop of the diodes, the drop across interconnects within the display (which tends to be quite resistive) and any drop needed in the display drivers (Figure 1).
|
|
|
BYTE CD-ROM |
| NOW, on one CD-ROM, you can instantly access more than
8 years of BYTE. |
| |
The Best of BYTE: Volume 2 - Heuristic Algorithms |
| In this volume of Best of BYTE, we explore the emergence of some heuristic algorithms. Although we have only scratched the surface of this intriguing subject, we hope we've suggested the potential of the synthesis of heuristics and algorithms. |
|
|
|
|
