Display Device Pulse-Width Modulation Brightness Control
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Solution Overview
Problem
Display devices with variable refresh rates experience screen flickering due to framerate variations, caused by differing processing times for image details, leading to blank frames and inconsistent brightness.
Innovation Solution
A display device with multiple pixel circuits, including an emission unit, transistors, and a pulse-width modulation circuit, which adjusts control signals to maintain consistent brightness across frames by correlating duty ratios with frame duration differences, ensuring adaptive brightness based on framerate variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the display device supports variable refresh rate to prevent frame tearing, then the display can dynamically adjust frame rate according to external graphic processor output frequency, but screen flickering occurs due to blank frames between different time intervals
Solution Approach 1:
The patent changes the parameter of light emission duration by controlling the conduction time of the second transistor through pulse-width modulation. By adjusting the duty ratio of control signals, the emission unit's on-time is modified to compensate for varying frame durations, maintaining consistent perceived brightness across frames with different time intervals.
Solution Approach 2:
The patent implements periodic light emission through the emission unit controlled by the second transistor, with the conduction time periodically adjusted according to frame timing. The pulse signal generates periodic control cycles that modulate the emission duration to match variable refresh rates while preventing flicker.
2Adaptability or versatility
If the external graphic processor sends display signals at different time intervals due to varying image detail complexity, then variable refresh rate is achieved, but blank frames appear causing screen flickering
Solution Approach 1:
The patent performs preliminary timing analysis by the control circuit to determine the appropriate conduction time for the second transistor before each frame is displayed. Based on the detected frame time interval, the control circuit pre-calculates and applies the correct pulse-width modulation duty ratio to ensure continuous perceived display without blank frames.
3Productivity
If the emitting signal repeatedly oscillates during each frame duration, then the pixel circuits can display the frame content, but brightness inconsistency occurs when frame durations vary
Solution Approach 1:
The patent implements a feedback mechanism where the control circuit detects the actual frame time interval and uses this information to adjust the duty ratio of the control signal for the second transistor. This closed-loop approach ensures that brightness remains consistent by adapting the emission duration to match the varying frame rates in real-time.
Data Source
AI summary
A driving method applicable to a display device, in which the display device includes multiple pixel circuits, and the method includes: adjusting multiple control signals according to a first display data such that the pixel circuits generate a first frame; receiving a second display data generated after the display data; and adjusting the control signals according to a time duration of the first frame such that the pixel circuits generate a second frame, where brightness for each of the pixel circuits is proportional to a duty ratio of one of the corresponding control signals, and an increment for the duty ratio of one of the corresponding control signals in the second frame is negatively correlated to a difference between a ratio of a preset time period to the time duration of the first frame and a ratio of the preset time period to the time duration of the second frame.