OLED Display Signal Controller Degradation Compensation
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Solution Overview
Problem
OLED displays face image quality deterioration and reduced lifespan due to degradation of organic light-emitting diodes (OLEDs) and driving transistors, which is not effectively compensated by existing pixel circuits that decrease the aperture ratio and have decreasing compensation over time.
Innovation Solution
A display device and driving method that include a signal controller generating data accumulations and modification coefficients to modify input image data, generating data voltages, and supplying them to pixels, which modulates image data to maintain luminance by accounting for degradation coefficients of OLEDs and transistors, thereby compensating for degradation without additional transistors or elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pixel circuits are added to compensate for OLED and transistor degradation, then image quality is maintained, but aperture ratio decreases due to additional transistors and signal lines
Solution Approach 1:
A gamma correction unit is introduced as an intermediary component between the image signal input and the pixel driving circuit. This unit applies gamma correction to the image signal, which indirectly compensates for the degradation characteristics of OLEDs and transistors without requiring additional transistors or signal lines in the pixel circuit itself, thus maintaining aperture ratio while improving image quality consistency
Solution Approach 2:
The invention changes the parameter of the image signal by applying gamma correction transformation. By modifying the signal characteristics before it reaches the pixel circuit, the system compensates for degradation effects through parameter transformation rather than through additional hardware components, thereby avoiding aperture ratio reduction
2Reliability
If pixel circuits with multiple transistors are used for degradation compensation, then OLED and transistor degradation is compensated, but device complexity increases
Solution Approach 1:
The degradation compensation function is extracted from the pixel circuit itself and moved to a separate gamma correction unit. This extraction removes the need for additional transistors and signal lines within the pixel circuit, reducing device complexity while maintaining the degradation compensation capability through external signal processing
Solution Approach 2:
The gamma correction unit serves as an intermediary that handles degradation compensation externally. By placing this compensation mechanism outside the pixel circuit, the invention avoids increasing the number of transistors and signal lines within the pixel, thus reducing overall device complexity while still achieving reliable degradation compensation
3Ease of manufacture
If conventional pixel circuits are used, then manufacturing is simpler, but compensation effectiveness decreases over time
Solution Approach 1:
Gamma correction is applied in advance to the image signal before it reaches the pixel circuit. This preliminary action pre-compensates for the degradation characteristics of OLEDs and transistors, ensuring that the pixel circuit operates with corrected signal values throughout its lifetime, thereby maintaining compensation effectiveness without modifying the pixel circuit structure
Data Source
AI summary
A display device includes: a plurality of pixels; a signal controller generating data accumulations for current image data for the pixels based on an accumulation of input image data, calculating modification coefficients according to the data accumulations, and modifying the current input image data based on the modification coefficients to generate modified image data; and a data driver generating data voltages corresponding to the modified image data and supplying the data voltages to the pixels.