In-Cell Touch Panel Driving Method for Signal Stability
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Solution Overview
Problem
In-cell touch panels experience display and touch performance issues due to signal delays and abnormalities when switching between normal display and touch scanning modes, leading to poor picture quality and other abnormalities.
Innovation Solution
Applying a first over driving voltage to the common electrode of each pixel when switching from normal display to touch scanning, and a second over driving voltage when switching back to normal display, to quickly reach preset voltage levels and mitigate signal delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If time-division multiplexing is used to drive touch circuit and display circuit, then both touch function and display function can be realized, but signal delay occurs during switching between modes causing display abnormalities and touch problems
Solution Approach 1:
The patent applies a first over-driving voltage to the common electrode before the switching moment from display mode to touch scanning mode, and a second over-driving voltage after the switching moment from touch scanning mode to display mode. This preliminary and follow-up action compensates for the inherent signal delay in the liquid crystal panel, ensuring the common electrode voltage reaches the target level timely and avoiding display abnormalities and touch detection failures during mode transitions.
2Ease of operation
If switching between direct-current signal for display and alternating-current signal for touch scanning, then display and touch functions are separated in time, but signal temporary abnormality occurs at switching moments
Solution Approach 1:
The patent changes the voltage parameter of the common electrode by applying over-driving voltages during switching moments. The first over-driving voltage is applied when switching from display to touch scanning, and the second over-driving voltage is applied when switching from touch scanning to display. This parameter change accelerates the voltage transition and ensures signal accuracy during mode switching.
Data Source
AI summary
A driving method for a liquid crystal panel is disclosed. Wherein, the driving method includes: (A) at a moment of switching from a normal display time stage to a touch scanning time stage in a current frame, applying a first over driving voltage to a common electrode of each pixel of a liquid crystal panel; and (B) at a moment of switching from the touch scanning time stage in the current frame to a normal display time stage of a next frame, applying a second over driving voltage to the common electrode of each pixel. According to the method described above a time that the common electrode reaches a present level voltage is shorten in order to effectively improve the poor display and touch problem caused by signal abnormality at moments of switching between a normal display and a touch scanning in an in-cell touch panel.