A Survey of Low-power Techniques for Liquid Crystal Display Systems with Light Emitting Diode Backlight Units

Abstract

As the technology evolves, end-users are stuffed with many kinds of handheld devices along with an enormous number of interactive multimedia applications and communication functionalities. These devices consume much power, especially for displaying their services or functions. In contrast, the battery, which is the main power supplier for such devices, has a much lower capacity growth compared to the power demands. This gap has inspired many researchers to study low-power display techniques. In the mean time, there came the invention of a light emitting diode (LED) as a new backlight source for a display panel. LEDs have been adopted in the most widely used Liquid Crystal Display (LCD) system. This paper focuses on recent noticeable low-power display techniques based on LCD systems, especially associated with an LED backlight unit as its light source. We categorize these techniques into four groups: 1) low-power techniques with backlight dimming, 2) low-power techniques with dynamic voltage scaling, 3) software-based low-power techniques, and 4) hardware-based low-power techniques, and review the core of each technique briefly. Among many techniques, concurrent brightness and contrast scaling technique in a color sequential LEDbacklit display system achieved the largest power saving ratio by up to 90% of the total system power with a small distortion level. As future research, it is one of important methods to combine the pros from each beneficial technique into one synergistically in the aspect of the whole system power.

Review of Display Technologies Focusing on Power Consumption

“…The possibility of combining the advantages of each technique into one collaboration to improve the whole power system is research for the future [87].…”

“…The main ones-LCD displays-are covered in the survey of Anggorosesar [87], which classifies the low-power techniques in four categories: backlight dimming, dynamic voltage scaling, software-based and hardware-based. They can achieve power saving ratios by up to 90% of the total system power with a small distortion level.…”

A Camera-Driven Power Management of Computer Display

“…Adaptive backlight dimming for both power reduction and contrast enhancement are studied in [16] and [17]. A survey of low-power techniques for LCD systems with lightemitting diode backlights can be found in [18].…”

Review : Power Saving Techniques for Display of Electronic Gadgets

“…for large screen. Now we will look into detail classification [2] of low power techniques for LED backlight unit based LCD systems. Obviously, the methods discussed below are using edge type backlight structures for LCDs.…”

“…A high mean value indicates that the backlight will be controlled to select a low current to save the system power based on different backlight current levels. Median=the middle value of X (i, j) after sorting (2) Level=floor (Mean (i, j)/0x20)…”