Variable Brightness LCD Backlight for Power Reduction
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Solution Overview
Problem
Conventional backlit LCD displays consume excessive power due to constant backlight illumination, leading to inefficiencies and reduced battery life, especially when displaying a combination of bright and dark images.
Innovation Solution
The system adjusts the backlight brightness based on the source image's pixel data, using multiple backlight segments with varying brightness levels to match the image's requirements, and calculates the LCD input image to control pixel brightness, ensuring the viewed image's brightness is similar to the source image's while minimizing power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the backlight source illuminates all pixels simultaneously with constant brightness, then the LCD display provides uniform illumination across the screen, but power consumption increases excessively
Solution Approach 1:
The backlight source is divided into multiple independently controllable segments or zones. Each segment can be adjusted to different brightness levels based on the local requirements of the displayed image content, allowing dark regions to use less light and bright regions to maintain sufficient illumination, thereby reducing overall power consumption while maintaining display quality
Solution Approach 2:
The backlight brightness is made dynamically adjustable rather than static. The system continuously monitors the image content and automatically adjusts the backlight intensity in real-time to match the displayed scene requirements, reducing power consumption during low-brightness scenes while maintaining optimal visibility during high-brightness scenes
2Illumination intensity
If voltage waveform is applied to LCD material to dim parts of the display, then local brightness control is achieved, but light from the backlight source is wasted
Solution Approach 1:
Instead of using the LCD material to block light after it has been generated, the system preliminarily adjusts the backlight intensity before light reaches the LCD panel. By pre-dimming the backlight in regions where dark display is needed, the system avoids generating excessive light that would subsequently be blocked and wasted, thereby reducing energy loss
Solution Approach 2:
The patent replaces the mechanical/optical approach of using LCD molecules to block light (which wastes energy) with an electrical control approach that adjusts backlight intensity directly. This substitution occurs at the light source level rather than at the light modulation level, improving energy efficiency
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces power consumption by ensuring only the necessary backlight intensity is used, specifically adjusting brightness for each pixel location, thereby decreasing overall power consumption and extending battery life.
Implementation Method 1
A backlight source 108 produces light to illuminate the LCD material 102
Implementation Method 2
The light from backlight source 108 typically passes through a polarizer 110 that blocks light that is not aligned with an axis of polarization of polarizer 110
Implementation Method 3
The LCD material 102 has electro-optic properties that causes the polarized light that passes through the LCD material 102 to twist
Implementation Method 4
The control circuit will apply a voltage waveform to the LCD material 102 for a pixel based on the digital control value for the pixel... less of the light is blocked by the second polarizer 112, thereby causing the pixel to appear brighter
Data Source
AI summary
A display for a computer system, such as an LCD, is configured to consume less power when compared to conventional designs. The display includes a screen and at least one backlight configured to illuminate the screen. An input to the at least one backlight is adjustable to produce a desired level of brightness. The input may be computed based on a generated source image and a defined constraint. An input to the display is computed based on the input to the at least one backlight and the source image. The input to the display modifies the level of brightness provided by the at least one backlight to produce a viewable image.