Luminance Adjustment Circuitry for Gate Line Loading Compensation
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Solution Overview
Problem
Organic light-emitting diode displays face brightness nonuniformity due to varying threshold voltages of drive transistors and capacitive loading effects, especially in displays with non-rectangular shapes, leading to performance issues.
Innovation Solution
Implementing gate drive circuits that generate row-location-dependent gate line signals and luminance adjustment circuitry to compensate image data based on pixel location, gray level, and temperature, along with range adjustment and dithering to ensure uniform brightness across the display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If gate drive circuits provide different gate line signals to different rows to compensate for capacitive loading variations, then brightness uniformity is improved, but device complexity increases
Solution Approach 1:
The display is divided into multiple row groups, with each group having its own gate drive circuit that generates tailored gate line signals. This segmentation allows different rows to receive customized compensation signals based on their specific capacitive loading conditions, achieving brightness uniformity while managing circuit complexity through modular organization.
Solution Approach 2:
Different rows or row groups receive different gate line signal characteristics (such as different rise times, fall times, or pulse widths) based on their local capacitive loading conditions. This local customization ensures that each row receives the optimal gate signal for its specific pixel count and loading requirements, improving brightness uniformity without requiring complete redesign of the entire gate drive system.
2Illumination intensity
If luminance adjustment circuitry compensates image data based on pixel location and gray level, then brightness uniformity is improved, but processing time increases
Solution Approach 1:
Compensation lookup tables are pre-calculated and stored in memory before the display operates. These tables contain pre-computed compensation values for different pixel locations and gray levels. During operation, the system simply queries these pre-prepared tables rather than performing complex real-time calculations, significantly reducing processing time while maintaining brightness uniformity.
Solution Approach 2:
Instead of performing complex mathematical operations to calculate compensation values in real-time, the system uses pre-computed lookup tables that store the results of such calculations. This approach copies the results of time-consuming computations into a format that can be quickly retrieved during actual display operation, reducing processing time while maintaining compensation accuracy.
3Adaptability or versatility
If range adjustment circuitry modifies compensated image data to fit desired range, then display compatibility is improved, but image quality may deteriorate due to clipping or distortion
Solution Approach 1:
The range adjustment process dynamically adapts to the actual content of the compensated image data. Rather than applying fixed clipping thresholds, the system analyzes the minimum and maximum values in the compensated data and adjusts the mapping range accordingly. This dynamic approach ensures that the full range of compensated values is utilized, preventing unnecessary clipping while maintaining compatibility with the display driver's expected input range.
Solution Approach 2:
The system changes the parameter mapping between the compensated image data and the display driver's expected range. By adjusting the scaling factors and offset values based on the actual data distribution, the system can preserve image quality while ensuring compatibility. This involves transforming the compensated values through adjustable parameters that optimize both the mapping to the desired range and the preservation of image details.
Data Source
AI summary
A display may have an array of pixels. Due to the presence of a notch in the display, the display may have some rows that are shorter than other rows in the display, and accordingly different gate line loading. To account for the gate line loading variations, the display driver circuitry may have gate driver circuits that provide different gate line signals to different rows of pixels within the display. In other arrangement, luminance adjustment circuitry may receive image data and generate corresponding compensated image data to account for gate line loading variations between rows of pixels in the display. The image data may be compensated based on the location of the pixel, the gray level of the image data, the display brightness, and/or temperature.