OLED Touchscreen Scan Timing to Prevent Display Flicker
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Solution Overview
Problem
Thinner OLED displays experience noticeable display flicker due to additional current draw required for touch sensing scans, which reduces current flow through the OLEDs and dims the screen.
Innovation Solution
Perform self-sensing scans during a blank period when pixels are not being driven, utilizing a tearing effect signal to restrict image display and maintain brightness by limiting current draw during these scans.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If touch sensing scans are performed on the touchscreen, then touch detection capability is improved, but additional current draw reduces current through OLEDs causing display flicker
Solution Approach 1:
The patent implements periodic touch sensing scans at specific intervals during the display refresh cycle. By scheduling scans periodically during blanking intervals or specific time windows, the system maintains touch detection capability while minimizing interference with OLED current drive, thus preventing display flicker.
Solution Approach 2:
The patent dynamically adjusts scanning parameters such as scan amplitude, frequency, and timing based on display state. By changing these parameters, the system optimizes the balance between touch sensing accuracy and OLED current consumption, ensuring stable display brightness while maintaining effective touch detection.
2Volume of moving object
If OLED displays are made thinner to increase flexibility and size, then device portability and display area are improved, but display flicker becomes increasingly noticeable
Solution Approach 1:
The patent performs preliminary compensation actions by pre-charging OLED pixels or adjusting drive currents before scanning operations. This preliminary action ensures that even when additional current is drawn for sensing, the OLEDs maintain sufficient current for stable light emission, reducing flicker in thinner displays.
Solution Approach 2:
The patent implements feedback mechanisms that monitor display brightness and adjust sensing parameters in real-time. When flicker is detected or anticipated, the system automatically adjusts scan timing or amplitude to maintain stable OLED current, making thinner displays less prone to noticeable flicker.
3Adaptability or versatility
If additional current is drawn for touch sensing scans, then touch detection function is enabled, but current flow through OLEDs is reduced dimming the screen
Solution Approach 1:
The patent segments the display refresh cycle into distinct time intervals, allocating specific periods for touch sensing scans and other periods for normal display operation. By dividing the time domain, the system enables touch detection functionality while ensuring that OLEDs receive sufficient current during non-scan intervals, preventing screen dimming.
Data Source
AI summary
An embodiment method for operating an electronic device includes transmitting, from a controller, a tearing effect (TE) signal to a touchscreen over a first period of time, the first period of time occurring during a first frame and having a duration that is shorter than a period of the first frame, the TE signal being configured to restrict image data from being displayed on the touchscreen during the first period of time; displaying the first frame of a plurality of frames of the image data on a display of the touchscreen over a second period of time within the period of the first frame other than during the first period of time; and detecting, at the controller, a first touch by performing a first self-sensing scan during the first period of time.