Active Matrix OLED Grayscale Stabilization via Power Feedback
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Solution Overview
Problem
In organic light emitting displays, changes in power supply voltage lead to variations in current supplied to pixel circuits, affecting the gray level of emitted light, resulting in reduced screen uniformity and degraded quality, especially as display size increases.
Innovation Solution
An organic light emitting display system that includes a switching unit, comparator, and adder to adjust the gamma voltage generator's reference power based on the difference between two source powers, ensuring a constant grayscale by stabilizing the voltage level of the reference power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate reference power source is used for the gamma voltage generator, then the gamma voltage can be generated independently, but the grayscale becomes unstable when power supply voltage changes
Solution Approach 1:
The patent combines the reference power source with the power supply system by using the power supply voltage itself as the reference power source for the gamma voltage generator, eliminating the need for a separate reference power source and ensuring that the reference power changes synchronously with the power supply voltage, thereby maintaining grayscale stability
Solution Approach 2:
The patent implements a feedback mechanism where the power supply voltage is fed back to the gamma voltage generator as the reference power source, allowing the gamma voltage to automatically adjust according to power supply voltage changes, thus maintaining stable grayscale output
2Area of stationary object
If the display panel size is increased, then the display area is enlarged, but the power supply stability decreases leading to degraded screen quality
Solution Approach 1:
By using the actual power supply voltage as the reference power source, the system creates a natural feedback loop that compensates for power supply instability, ensuring that grayscale remains consistent across larger display areas where power supply stability is more challenging to maintain
Data Source
AI summary
An organic light emitting display keeps a constant grayscale in an organic light emitting display panel even if power supplied by a power supply is changed. The organic light emitting display includes: a switching unit for selecting and outputting a first source power or a second source power as a first reference power; a comparator for comparing the first reference power with the second source power and outputting a difference value between the first reference power and the second source power; an adder for adding the difference value to an initial second reference power to output as a second reference power, such that a voltage level of the second reference power is changed when a voltage level of the first reference power is changed; and a gamma voltage generator for generating plural gamma voltages to be utilized for displaying the image on an organic light emitting display panel by utilizing the first and second reference powers.