PWM Control for Display Dynamic False Contour Reduction
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Solution Overview
Problem
Active matrix displays experience dynamic false contour due to significant differences in light emitting times between adjacent sub-pixels, leading to perceived gradations as 0 or 64 instead of intermediate values, causing display distortion.
Innovation Solution
A display apparatus and method that includes a controller to alter the order of image data output from the data driving circuit and the order of pulses from the clock driving circuit, either between frames or between rows, and to divide pulses into sub-pulses, ensuring uniform distribution of driving and non-driving times for sub-pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If PWM signals are sequentially input to sub-pixels from MSB to LSB, then the control method is simple and straightforward, but large differences in light emitting time occur between adjacent gradations causing dynamic false contour
Solution Approach 1:
The patent applies dynamics by making the PWM signal output order changeable rather than fixed. The controller dynamically adjusts the output sequence between MSB-first and LSB-first modes depending on the frame number, enabling adaptive optimization of light emitting time uniformity while maintaining implementation simplicity
Solution Approach 2:
The patent implements periodic action by alternating the PWM signal output order between consecutive frames. Odd frames use MSB-first ordering while even frames use LSB-first ordering, creating a periodic pattern that averages out light emitting time differences and eliminates dynamic false contour
2Device complexity
If PWM signals are input in fixed order, then the control logic is simple, but display distortion occurs due to perceived gradations as 0 or 64 instead of intermediate values
Solution Approach 1:
The control logic becomes dynamic by using the frame number to determine the PWM output order. This conditional logic, while slightly more complex than fixed ordering, ensures accurate intermediate gradation display by preventing the systematic bias that causes distortion
Solution Approach 2:
The patent uses periodic alternation between MSB-first and LSB-first PWM output orders to eliminate systematic display distortion. This periodic switching ensures that intermediate gradations are displayed accurately by averaging out the timing differences across frames
Data Source
AI summary
A display apparatus is capable of improving a dynamic false contour. The display apparatus may control to change an order of a plurality of pulses of which widths are modulated for an emission time set within one frame, or divide pulses corresponding to the most significant bit (MSB) and the second significant bit (MSB-1) of image data among the pulses into two or more sub-pulses, and output the sub-pulses.