OLED Emission Driver Duty Cycle Control via Segmented Timing
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Solution Overview
Problem
Conventional organic light emitting display (OLED) drivers are unable to independently control the emission signal to achieve a desired OFF level duration and struggle with generating duty ratios of 50% or greater, limiting the implementation of effective duty driving methods.
Innovation Solution
The proposed solution involves an organic light emitting display with a data driver, gate driver, and emission driver configuration that includes a timing controller to generate duty timing control signals, allowing the emission driver to switch the emission control signal between ON and OFF levels independently, enabling precise duty driving and PWM modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional EM driver generates output in clock timing synchronized with gate driver, then the system maintains simple timing control, but it cannot control the EM signal to be in OFF level for desired time independent of data and cannot generate duty ratio of 50% or greater
Solution Approach 1:
The patent divides the display operation into two distinct periods: a scan period for data writing and a duty driving period for emission control. This segmentation allows independent control of the EM signal during the duty driving period, enabling duty ratios of 50% or greater while maintaining simple timing control through separate functional phases.
Solution Approach 2:
Data is written to pixels during the scan period before the duty driving period begins. This preliminary action ensures that pixel data is prepared in advance, allowing the EM signal to be controlled independently during the subsequent duty driving period without affecting data integrity, thus achieving high duty ratios with simple timing control.
2Adaptability or versatility
If duty driving method is implemented with independent EM signal control, then desired OFF level duration and high duty ratios are achieved, but the driver structure becomes more complex
Solution Approach 1:
The patent implements dynamic control of the EM signal by switching between different operational modes: during the scan period, the EM signal follows clock timing for simple control, while during the duty driving period, the EM signal can be independently controlled to achieve desired duty ratios. This dynamic adaptation allows high versatility in duty ratio control without permanently increasing driver complexity.
Solution Approach 2:
The display operation alternates between a scan period and a duty driving period in a periodic fashion. This periodic action structure enables the system to achieve high duty ratios during the duty driving period while maintaining simple timing control during the scan period, thus providing adaptability without permanent structural complexity.
3Illumination intensity
If OLED pixels are turned on and off repeatedly with PWM duty ratio, then luminance control is achieved, but response time increases and flicker may occur
Solution Approach 1:
The patent maintains continuous data voltage in pixels throughout both the scan period and duty driving period. This continuity ensures that pixels are always ready to emit light at full intensity when the EM signal is active, eliminating response time delays that would occur from repeatedly switching data voltage. The useful action of light emission is maintained continuously during the duty driving period, preventing flicker while achieving luminance control through duty cycle adjustment.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enables the OLED pixels to be turned on and off repeatedly with controlled luminance, reducing response time and preventing flicker, while maintaining data voltage without additional data addressing, thus enhancing display performance and preventing residual images.
Implementation Method 1
If a driving voltage is applied to the anode and the cathode, a hole passed through the HTL and an electrode passed through the ETL move to the EML to form an exciton. As a result, the EML generates a visible light.
Data Source
AI summary
An organic light emitting display comprises a display panel having data lines, scan lines, emission signal lines, and pixels. The display also comprises a data driver configured to provide a data voltage corresponding to an input image to one of the data lines connected to a pixel and a gate driver configured to provide an N-th scan pulse to an N-th scan line to charge the pixel with the data voltage during a scan period within a frame period. The display further comprises an emission driver configured to receives shift clocks and the N-th scan pulse from the gate driver to provide an N-th emission control signal to the N-th emission signal line and to control a current path through the OLED based on the N-th emission control signal during a duty driving period following the scan period within a frame period.