Touchscreen Display Flicker Mitigation in LFD Mode
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
OLED displays in low frequency display (LFD) mode experience noticeable flicker due to additional current draw during self-sensing scans, which occurs when these scans are performed at the same start position within each frame, combining with the reduced refresh rate.
Innovation Solution
The touchscreen controller adjusts the start time of self-sensing scans in LFD mode to stagger them across frames, ensuring the current draw does not coincide with the refresh of the same row of pixels, thereby preventing flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If self-sensing scans are performed at the same start position in each frame during LFD mode, then touch sensing functionality is maintained, but display flicker occurs due to additional current draw coinciding with pixel refresh
Solution Approach 1:
The patent applies dynamics by making the self-sensing scan start position variable rather than fixed. The scan start position is dynamically adjusted based on the frame number, specifically offsetting by different row positions in different frames during LFD mode. This dynamic adjustment prevents the scan current from consistently coinciding with the same pixel refresh timing, thereby eliminating flicker while maintaining touch sensing functionality.
2Loss of energy
If OLED display operates in LFD mode with reduced refresh rate, then power consumption is reduced, but flicker becomes noticeable when self-sensing scans are performed
Solution Approach 1:
The patent maintains LFD mode operation with reduced refresh rate for power savings, but introduces dynamic adjustment of self-sensing scan timing. By offsetting the scan start position based on frame number and calculating appropriate scan timing, the patent eliminates flicker without increasing the display refresh rate, thus preserving the power consumption benefits of LFD mode.
3Object-affected harmful factors
If self-sensing scan timing is adjusted to prevent flicker in LFD mode, then display quality is improved, but scan timing complexity increases
Solution Approach 1:
The patent implements dynamic scan timing adjustment using a systematic approach: determining current frame number, calculating offset based on frame number and row position, and adjusting scan start timing accordingly. This structured dynamic control method achieves flicker elimination with manageable complexity through clear computational rules rather than requiring complex hardware modifications.
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 approach effectively mitigates display flicker in OLED displays operating in LFD mode by distributing the additional current draw across different frames, maintaining brightness and reducing noticeable flicker for the user.
Implementation Method 1
Each pixel may include an OLED configured to generate light based on the current driven through it
Data Source
AI summary
A method for operating an electronic device, including: determining that a touchscreen is in a low frequency display (LFD) mode, determining whether a self-sensing scan was performed in a previous frame of a plurality of frames; after determining, a self-sensing scan was performed in the previous frame, determining a current duration of time corresponding to a current frame based on a previous duration of time corresponding to the previous frame, the previous frame being a frame immediately preceding the current frame; determining, whether the current duration of time is greater than the previous duration of time; and after determining that the current duration is greater than the previous duration, performing a self-sensing scan after the current duration of time, the current duration of time being measured from a beginning of the current frame, the current duration of time having a duration less than a duration of the current frame.