Asynchronous Touch Drive Signal Timing for OLED Noise
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Solution Overview
Problem
In display devices with both display and touch functions, such as OLED touch screens, the touch layer is often interfered by display noise signals during level switching, affecting touch detection accuracy, and existing synchronous and asynchronous touch drive methods either limit touch scan frequency or introduce noise interference.
Innovation Solution
An asynchronous touch drive method where the touch scan frequency differs from the display scan frequency, with touch scan signals having rising and falling edges outside noise durations, and a display mask signal is generated to maintain the touch scan signal at effective levels, avoiding noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If synchronous touch drive method is used, then touch detection can be performed during display operation, but touch scan frequency is limited by display scan frequency
Solution Approach 1:
The patent applies dynamics by making the touch scan frequency independent and adjustable relative to the display scan frequency. The touch controller can dynamically set the touch scan frequency based on touch detection needs without being constrained by the fixed display refresh rate, allowing flexible adaptation to different touch interaction scenarios.
Solution Approach 2:
The patent segments the timing control of touch and display operations by introducing separate scan frequency controls. The touch scan signal and display scan signal are generated independently with different frequencies, allowing each subsystem to operate optimally without mutual constraint, thus resolving the frequency limitation while managing interference through temporal separation.
2Productivity
If asynchronous touch drive method is used to increase touch scan frequency, then touch detection responsiveness improves, but display noise signal interferes with touch detection accuracy
Solution Approach 1:
The patent employs periodic action by using the display mask signal that is generated at regular intervals synchronized with the display refresh cycle. This mask signal periodically blocks touch scan operations during the horizontal synchronization period when display noise occurs, allowing high-frequency touch scanning during safe periods while maintaining accurate touch detection.
Solution Approach 2:
The patent applies preliminary anti-action by proactively blocking touch scan signals during periods when display noise is expected to occur. The display mask signal is generated in advance based on the known display timing, and touch scanning is prevented during these predetermined noisy periods, thereby eliminating noise interference before it can affect touch detection accuracy.
3Ease of operation
If touch scan signal level switching occurs during noise duration, then touch scan flexibility increases, but signal-to-noise ratio deteriorates
Solution Approach 1:
The patent introduces the display mask signal as an intermediary that mediates between the touch scan signal and display noise. The mask signal acts as a gatekeeper, allowing touch scan level switching only during periods when the display is not generating noise, thus maintaining both operational flexibility and signal quality by controlling when transitions can occur.
Data Source
AI summary
A touch drive method, a touch display device, and an electronic equipment are provided. The touch display device includes a display structure and a touch structure stacked with the display structure, a touch scan frequency of the touch structure is different from a display scan frequency of the display structure, and the touch drive method includes: applying a touch scan signal to the touch structure during a process in which the display structure performs progressive scan in respond to a row synchronization signal; a display noise signal is generated during at least one level switching process of the row synchronization signal; and each period of the touch scan signal has a signal rising edge and a signal falling edge, and the signal rising edge and the signal falling edge of each period of the touch scan signal are respectively located outside a noise duration of the display noise signal.