Pixel Circuit Pulse Compensation for Low-Refresh OLED Flicker
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Flicker phenomena occur in OLED displays operating at low refresh rates due to variations in current caused by leakage current and hysteresis effects of transistors, degrading display image quality.
Innovation Solution
A driving method for pixel circuits that involves measuring the initial brightness waveform, modulating the number and pulse width of pulse signals in each display frame to generate a compensated light-emission control signal, and applying it to the pixel circuit to stabilize the brightness waveform.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the pixel circuit is operated at a low refresh rate to reduce power consumption, then power consumption is reduced and single-use duration is prolonged, but leakage current and hysteresis effects of transistors cause current variation leading to brightness variation and flicker phenomena
Solution Approach 1:
The patent applies preliminary action by measuring the brightness waveform of the light-emitting element before the actual display operation. This preliminary measurement allows the system to obtain characteristics of the light-emitting element's response, including any leakage current or hysteresis effects, so that compensation can be prepared in advance. The measured brightness waveform is then used to generate compensation data that is applied during subsequent display frames, preventing brightness variation before it occurs.
Solution Approach 2:
The patent implements feedback by using the measured brightness waveform to generate a compensation signal that is fed back into the display system. The brightness waveform measurement provides feedback about the actual light output, which is then used to adjust the drive signals. This closed-loop feedback mechanism continuously compensates for leakage current and hysteresis effects, maintaining stable brightness despite the low refresh rate operation.
2Reliability
If the number of pulse signals in each display frame is increased to stabilize brightness waveform, then flicker phenomena are mitigated, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing each display frame into multiple sub-frames, with each sub-frame containing one or more pulse signals. Instead of using a single pulse signal per frame, the frame is segmented into multiple temporal segments, each with its own pulse signal. This segmentation allows the system to apply multiple compensation cycles within a single display frame, stabilizing the brightness waveform more effectively while keeping each individual pulse signal relatively simple.
Solution Approach 2:
The patent implements dynamics by making the pulse signal parameters (number of signals, pulse width, timing) adjustable rather than fixed. The system dynamically adapts these parameters based on the measured brightness waveform and the specific requirements of each display frame. This dynamic adjustment allows the system to optimize brightness stability without permanently increasing device complexity, as the complexity can be adjusted according to actual operating conditions.
Data Source
AI summary
A driving method of a pixel circuit includes: providing a preset light-emission control signal to the pixel circuit, in which the pixel circuit includes a light-emitting element; measuring the light-emitting element while the light-emitting element emits light according to the preset light-emission control signal, thereby obtaining an initial instantaneous brightness waveform of the light-emitting element; and modulating the number of plural pulse signals included in each display frame of the preset light-emission control signal and the pulse width of each of the pulse signals according to the initial instantaneous brightness waveform, thereby generating a compensated light-emission control signal; and providing the compensated light-emission control signal to the pixel circuit. In response to the light-emitting element emitting light according to the compensated light-emission control signal, an instantaneous brightness waveform of the light-emitting element appears to converge in each display frame.