LCD Gamma Curve Adjustment for Illuminance-Dependent Brightness
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Solution Overview
Problem
Liquid crystal displays experience image quality distortion due to changes in external light environments, as they maintain a fixed gamma curve regardless of illuminance, leading to uneven brightness and linearity across gray levels.
Innovation Solution
A liquid crystal display system equipped with an external light sensing unit and a gamma curve adjusting circuit that modulates digital video data based on illuminance, expanding gray levels and adjusting gamma curves to maintain relative brightness and linearity across all gray levels, regardless of environmental changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed gamma curve is used for displaying images, then the display structure remains simple and stable, but image quality distortion occurs under varying external light conditions
Solution Approach 1:
The patent applies dynamics by making the gamma curve adjustable rather than fixed. The system dynamically changes gamma curve parameters based on detected external light conditions, allowing the display to adapt to varying illuminance levels while maintaining image quality consistency across different environments
Solution Approach 2:
The patent implements feedback through an external light sensor that detects illuminance levels and feeds this information to the gamma curve adjustment mechanism. This closed-loop feedback system automatically adjusts the gamma curve to compensate for changes in external lighting, preventing image quality distortion without requiring manual intervention
2Manufacturing precision
If the gamma curve is adjusted to match external light conditions, then image quality linearity improves across gray levels, but the processing complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying gamma curve parameters (such as gamma value and offset) based on detected external light conditions. The system changes these parameters dynamically to maintain proper brightness linearity across all gray levels, whether in bright, dim, or variable lighting environments
Solution Approach 2:
The patent implements preliminary action by pre-calculating and storing multiple gamma curve configurations corresponding to different illuminance levels. When the external light sensor detects a specific lighting condition, the system quickly switches to the pre-prepared gamma curve configuration, avoiding complex real-time calculations and reducing processing complexity
3Device complexity
If no gamma curve adjustment is made, then the device complexity remains low, but brightness uniformity and linearity deteriorate in varying light environments
Solution Approach 1:
The patent implements feedback through an external light sensor that detects illuminance levels and feeds this information to the gamma curve adjustment mechanism. This closed-loop feedback system automatically adjusts the gamma curve to compensate for changes in external lighting, preventing image quality distortion without requiring manual intervention
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 system ensures uniform relative brightness and improved linearity of perceived image quality across varying illuminance conditions, preventing distortion and glare issues in different lighting environments.
Implementation Method 1
controlling a light transmittance of a liquid crystal layer using an electric field applied to the liquid crystal layer
Implementation Method 2
an electric field between the pixel electrode and the common electrode, and thus incident light is modulated
Data Source
AI summary
A liquid crystal display and a method of driving the same are disclosed. The liquid crystal display includes a liquid crystal display panel for displaying an image, an external light sensing unit for sensing an illuminance of external light around the liquid crystal display panel, a backlight unit whose an output luminance is controlled by an adjustment dimming signal, and a gamma curve adjusting circuit for modulating digital video data or varying resistances of variable resistors constituting a gamma resistor string based on the illuminance of external light or according to a relative maximum white luminance based on the adjustment dimming signal, so as to uniformly keep a relative brightness of the input image a user perceives irrespective of changes in the illuminance of external light.