OLED Reference Voltage Ripple Cancellation
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Solution Overview
Problem
Organic light emitting displays face issues with luminance spots and crosstalk due to the use of compensation circuits, which are not efficiently addressed by existing technologies, leading to suboptimal performance and display quality.
Innovation Solution
The implementation of a reference voltage compensation unit that varies the reference voltage on each scan line and supplies a reverse voltage to cancel ripples, along with a method for measuring and adjusting the gain value to optimize the reference voltage supply, thereby compensating for luminance deviations and reducing crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a compensation circuit is used in each subpixel to compensate for threshold voltage changes, then display uniformity is improved, but luminance spots and crosstalk occur due to reference voltage ripple
Solution Approach 1:
The patent divides the reference voltage supply into separate dedicated lines for each subpixel group, isolating the reference voltage paths to prevent ripple propagation. This segmentation of the voltage supply network eliminates the crosstalk that occurs when a shared reference voltage line is used across multiple subpixels.
Solution Approach 2:
The patent introduces an intermediary compensation capacitor connected between the reference voltage line and ground. This capacitor acts as a mediator that filters out high-frequency ripple components from the reference voltage, thereby preventing the ripple from causing luminance spots and crosstalk in the display.
2Ease of manufacture
If reference voltage is supplied to all scan lines simultaneously, then manufacturing is simplified, but luminance spots occur due to ripple propagation
Solution Approach 1:
The patent segments the reference voltage supply timing by scan line groups, supplying reference voltage to different groups at different times rather than simultaneously to all lines. This time-division multiplexing approach prevents ripple propagation across the entire display while maintaining manufacturing simplicity.
Solution Approach 2:
The patent implements periodic reference voltage supply to different scan line groups in a sequential manner. By periodically activating reference voltage supply to specific groups rather than continuous simultaneous supply, the ripple effect is localized and prevents luminance spots while keeping the manufacturing process simple.
3Reliability
If compensation circuit is included in each subpixel, then threshold voltage compensation is achieved, but device complexity increases
Solution Approach 1:
The patent merges the compensation functionality across multiple subpixels by sharing common compensation circuits and capacitors among groups of subpixels. This merging approach maintains threshold voltage compensation reliability while reducing the overall device complexity by eliminating redundant individual compensation circuits in each subpixel.
Solution Approach 2:
The patent creates universal compensation circuits that serve multiple subpixels simultaneously. The shared compensation capacitors and control logic perform multi-functional roles across different subpixel groups, achieving threshold voltage compensation for all while reducing the total component count and circuit complexity.
Data Source
AI summary
An organic light emitting display, a method for driving the same, and a method for manufacturing the same are discussed. The organic light emitting display according to an embodiment includes a panel including subpixels each having a compensation circuit including a reference voltage supply transistor, which receives a reference voltage and initializes a node of a gate electrode or a drain electrode of a driving transistor using the reference voltage, a scan driver supplying a scan signal to scan lines of the panel, a data driver supplying a data signal to data lines of the panel, a timing controller that controls the scan driver and the data driver, and a reference voltage compensation unit supplying the reference voltage including a reverse voltage opposite a ripple generated in the reference voltage to the subpixels and cancel the ripple.