LCD Driver Voltage Offset Circuit for Brightness Uniformity
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Solution Overview
Problem
Existing LCD driver technologies face challenges in achieving brightness uniformity due to waveform distortion caused by resistances and capacitances in the LCD panel, leading to non-uniform gray levels and increased power consumption when attempting to address these issues.
Innovation Solution
An LCD driver with a detection-count circuit that calculates the number of waiting voltage offsets during a scanning period and shifts data electrodes to an intermediate potential for a proportional offset time, reducing effective voltage loss and contrast degradation without requiring additional offset voltages or increasing power supply complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If voltage offset is applied to compensate for waveform distortion, then brightness uniformity is improved, but power consumption increases
Solution Approach 1:
The patent applies voltage offset in advance during non-display periods (when scanning electrodes are at non-selection potential) to compensate for waveform distortion before actual display occurs. The detection-count circuit calculates the required offset timing based on data electrode transitions, and the offset is applied preliminarily without affecting display power consumption.
Solution Approach 2:
The patent segments the voltage offset application into specific time periods - applying offset only when scanning electrodes are at non-selection potential (V3) and data electrodes are transitioning, rather than continuously applying offset during entire display periods. This segmentation reduces overall power consumption while maintaining brightness uniformity.
2Illumination intensity
If additional offset voltage is introduced to correct waveform distortion, then brightness uniformity is improved, but device complexity increases
Solution Approach 1:
The patent makes the existing data electrode voltage transitions serve dual purposes: both displaying image data and providing the offset timing signal for waveform distortion compensation. The detection-count circuit detects data electrode voltage changes that would normally be part of display operation, and uses these same transitions to trigger offset application, eliminating the need for separate offset voltage generation circuits.
Solution Approach 2:
The system uses its own data electrode voltage transitions to generate the offset timing signals needed for compensation. The detection-count circuit monitors data electrode potential changes (V2/V4 transitions) that are inherently part of normal display operation, and automatically converts these into offset control signals, making the system self-regulating without external intervention.
3Illumination intensity
If voltage offset is applied during scanning period, then brightness uniformity is improved, but effective voltage and contrast are reduced
Solution Approach 1:
The patent applies voltage offset periodically during non-display periods when scanning electrodes are at non-selection potential (V3), creating a rhythmic pattern of offset application that synchronizes with the display refresh cycle. This periodic offset application corrects accumulation of waveform distortion without interfering with the effective voltage during actual display periods, thereby maintaining contrast.
Data Source
AI summary
The present invention discloses an LCD driver and LCD driving method for improving brightness uniformity, wherein a detection-count circuit is used to calculate a number of waiting voltage offsets of each one of data electrodes during a scanning period, convert the number of waiting voltage offsets into an offset time, shift a data electrode to an intermediate potential during the offset time, and shift the data electrode to a potential for a next piece of data after the offset time is completed. Thereby, the present invention can reduce LCD brightness non-uniformity and promote LCD quality.