Display Panel Timing Control for Low Brightness Color Cast Reduction
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Solution Overview
Problem
In low brightness mode, display panels exhibit a color cast phenomenon when switching between black and white images due to hysteresis effects in driving transistors and varying capacitances of light-emitting elements.
Innovation Solution
The display panel incorporates a pixel circuit with a light emission control module that adjusts light emission based on specific timing signals, including a first mode where the interval between valid pulses in consecutive data writing cycles is optimized to enhance light emission continuity and reduce color cast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the display panel operates in low brightness mode with conventional timing signals, then power consumption is reduced, but color cast phenomenon occurs when switching between black and white images
Solution Approach 1:
The patent applies preliminary action by adjusting the timing of reset signals and light emission control signals before the actual light emission occurs. Specifically, the reset signal is applied earlier in the frame period, and the light emission control signal timing is optimized to compensate for hysteresis effects, ensuring that the organic light-emitting elements are properly prepared for the upcoming display frame, thereby preventing color cast while maintaining low brightness operation
Solution Approach 2:
The patent applies parameter changes by modifying the timing parameters of control signals (reset signal timing, light emission control signal duty cycle, and signal interval parameters t1 and t2) to compensate for the hysteresis effects in organic light-emitting elements. These parameter adjustments optimize the electrical characteristics during low brightness operation, eliminating color cast phenomenon while maintaining energy efficiency
2Speed
If the light emission control signal has a short duration, then the response time is reduced, but the brightness of the first frame image is insufficient
Solution Approach 1:
The patent applies preliminary action by extending the light emission control signal into the previous frame period (into the black interval before the current frame). This allows the organic light-emitting elements to begin emitting light earlier, ensuring that the first frame image achieves adequate brightness without requiring a longer signal duration within the active display period, thus maintaining fast response time while improving initial brightness
3Productivity
If the interval between valid pulses in consecutive data writing cycles is shortened, then the refresh rate is increased, but the light emission continuity is reduced causing color cast
Solution Approach 1:
The patent applies parameter changes by optimizing the interval parameters t1 (between start of first valid pulse in (i+1)-th cycle and end of last second valid pulse in i-th cycle) and t2 (duration of light emission control signal being invalid pulse in data writing phase). These parameter adjustments ensure sufficient light emission continuity even at high refresh rates, preventing color cast while maintaining high productivity
Data Source
AI summary
The present disclosure discloses a display panel, a driving circuit and a display device. The display panel includes a pixel circuit and a light-emitting element. A data writing cycle of the pixel circuit includes a data writing phase and m holding phases. In the data writing phase, the first scan signal includes at least one first valid pulse. A light emission control signal includes one second valid pulse in the data writing phase and in each holding phase. The working modes of the display panel includes a first mode. In the first mode, the interval between the start time of the first valid pulse in the (i+1)-th data writing cycle and the end time of the last second valid pulse in the i-th data writing cycle is t1, and in the data writing phase, the duration of the light emission control signal being an invalid pulse is t2,t1t2≥1%,m≥1,i≥1,and m and i are integers.