LCD Local Dimming Circuit with Low Pass Filtering
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Solution Overview
Problem
Conventional local dimming methods for liquid crystal display devices cause luminescence unevenness and flickers between neighboring blocks, requiring complex circuit configurations and complicated algorithms, which restrict the improvement of contrast characteristics and increase power consumption.
Innovation Solution
A liquid crystal display device with a simplified dimming circuit that divides the backlight into blocks, uses a controller to analyze video data, generates block and local dimming values through low pass filtering, and applies a global dimming value to produce a dimming signal for PWM control of light sources, thereby reducing luminescence differences and flickers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional local dimming method is used to improve static contrast, then contrast characteristics are improved, but luminescence unevenness and flickers occur between neighboring blocks
Solution Approach 1:
The patent applies feedback by using low pass filtering on block dimming values to generate local dimming values. The filtering process continuously adjusts the dimming levels based on previous frame data, creating a feedback mechanism that smooths transitions between frames and reduces flicker while maintaining contrast improvement benefits
Solution Approach 2:
The patent performs preliminary action by pre-calculating block dimming values from video data analysis before applying them to the backlight units. This preliminary processing allows the system to prepare appropriate dimming levels in advance, preventing luminescence unevenness and flicker during actual display operation
2Adaptability or versatility
If conventional local dimming circuit is implemented to achieve local dimming, then local dimming function is realized, but circuit configuration becomes complex and algorithm becomes complicated
Solution Approach 1:
The patent merges the local dimming control function into the timing controller, combining multiple functions (video data analysis, block dimming value generation, low pass filtering, and PWM signal generation) into a single integrated controller. This eliminates the need for separate complex local dimming circuits while maintaining the local dimming capability
Solution Approach 2:
The timing controller is designed with universal functionality to perform both standard timing control and local dimming control operations. By making the controller multi-functional, the patent eliminates the need for dedicated local dimming circuitry, thereby simplifying the overall circuit configuration while preserving local dimming adaptability
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 enhances contrast characteristics, reduces electric power consumption, and simplifies the dimming circuit configuration by minimizing luminescence differences and flickers between blocks, improving both dynamic and static contrast.
Implementation Method 1
a backlight driver generating a PWM signal for controlling a luminescence of the light sources by the blocks respectively according to the dimming signal
Implementation Method 2
irradiating lights of which luminescence is controlled by the blocks, respectively
Data Source
AI summary
A liquid crystal display device and a dimming controlling method thereof are disclosed. The liquid crystal display device includes a liquid crystal display panel, a drive circuit supplying a data pulse and a gate pulse to the liquid crystal display panel, a backlight unit divided into a plurality of block including light sources, and irradiating lights of which luminescence is controlled by the blocks, respectively, a controller analyzing an input video data by the block unit, generating a block dimming value based on a result of the analyzing, repeating a low pass filtering to the block dimming value to generate a local dimming value, applying a predeterminded global dimming value to an average of the local dimming value to generate a dimming signal, and a backlight driver generating a PWM signal for controlling a luminescence of the light sources by the blocks respectively according to the dimming signal to drive the light sources by the blocks respectively.