Backlight Control for LCD Flicker Reduction
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Solution Overview
Problem
Conventional LCD devices experience flicker in image display due to improper setting of backlight emission brightness and pixel aperture ratio, leading to inconsistent display brightness across different areas of an image, especially when bright and dark regions are present.
Innovation Solution
A display device with individually controllable light sources for each area, using a nonlinear conversion table to set emission brightness and adjust pixel transmittance based on image signals, ensuring optimal backlight control values are supplied to maintain consistent display brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the emission brightness of the backlight is increased to display bright areas, then the display brightness in bright areas is improved, but the power consumption increases
Solution Approach 1:
The backlight is divided into multiple independently controllable light sources corresponding to different areas of the display screen. This allows each light source to be controlled separately according to the brightness requirements of its corresponding area, enabling bright areas to receive higher emission brightness while dark areas receive lower emission brightness, thus reducing overall power consumption while maintaining display quality where needed
Solution Approach 2:
Different emission brightness levels are applied to different areas of the backlight based on the local brightness requirements of the displayed image. Bright areas of the image correspond to light sources with higher emission brightness, while dark areas correspond to light sources with lower emission brightness, achieving energy efficiency through localized quality adjustment
2Illumination intensity
If the emission brightness of the backlight and aperture ratio of pixels are controlled in units of images, then the display brightness can be optimized, but image flicker occurs when there are errors in the relationship between emission brightness and aperture ratio
Solution Approach 1:
The system calculates the display brightness based on the relationship between emission brightness of light sources and aperture ratio of pixels, and uses this calculated value as feedback to adjust and optimize the emission brightness settings. This feedback mechanism ensures accurate control of display brightness while maintaining consistency across different images, preventing flicker by compensating for any errors in the emission brightness-aperture ratio relationship
3Illumination intensity
If the emission brightness of the backlight is set to maximum intensity, then sufficient display brightness can be obtained in all areas, but power consumption becomes excessively high
Solution Approach 1:
The backlight is segmented into multiple independently controllable light sources, allowing each light source to operate at the minimum necessary emission brightness for its corresponding display area. This eliminates the need to run the entire backlight at maximum intensity, significantly reducing power consumption while maintaining sufficient display brightness where required by the image content
Solution Approach 2:
Instead of applying maximum emission brightness uniformly across all light sources, the system applies emission brightness partially and selectively only to the extent needed for each specific area based on the displayed image content. This partial action approach achieves the minimum necessary display brightness while avoiding excessive energy consumption
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
The solution effectively reduces image flicker by maintaining consistent display brightness across varying image regions, improving visual stability and reducing power consumption.
Implementation Method 1
In the LCD device, twist of liquid crystal molecules in the liquid crystal layer is controlled by changing a voltage. Light beams from the backlight passed through the liquid crystal layer in accordance with the twist of the liquid crystal molecules pass through the color filter substrate
Data Source
AI summary
A display device to display an image corresponding to image signals in a display area is provided. The display device includes a backlight including individually placed light sources corresponding to areas in the display area; a panel that includes pixels corresponding to the display area and that changes transmittance of light from the light sources in units of pixels; a panel control unit to individually set emission brightness of each of the light sources in accordance with the image signals and set the transmittance of light in each of the pixels in accordance with the emission brightness; a storage unit to store a nonlinear conversion table to convert the emission brightness to a light source control value for the backlight; and a backlight control unit to convert the emission brightness to the light source control value in accordance with the nonlinear conversion table and supply the light source control value to the backlight.