Full In-Cell Touch Common Electrode Voltage Switching
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Solution Overview
Problem
In Full In-Cell Touch devices, the DC voltage difference between the reference and common electrode signals affects the normal deflection of liquid crystals, impacting display quality during the display period.
Innovation Solution
The touch device includes a common electrode, an induction electrode, and a detection circuit, where the common electrode loads a common electrode signal that is the same as the reference signal during the display period, eliminating the voltage difference and ensuring proper liquid crystal deflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the common electrode loads a negative voltage common electrode signal while the detection circuit loads a positive voltage reference signal, then the detection circuit can normally detect touch signals, but a DC voltage difference is generated that causes vertical deflection of liquid crystal and affects normal display
Solution Approach 1:
The patent dynamically adjusts the common electrode signal voltage based on the operating mode: during touch detection period, the common electrode loads a negative voltage signal to enable touch detection; during display period, the common electrode loads a positive voltage signal that matches the reference signal voltage, eliminating DC voltage difference and preventing liquid crystal deflection. This dynamic voltage switching resolves the contradiction between touch detection accuracy and display quality.
Solution Approach 2:
The patent changes the voltage parameter of the common electrode signal according to different time periods. The voltage is switched between negative (for touch detection) and positive (for display), with the positive voltage specifically designed to be equal to the reference signal voltage. This parameter change eliminates the harmful DC voltage difference during display while maintaining detection capability during touch period.
2Adaptability or versatility
If time-sharing driving is implemented to perform display and touch driving separately, then both display and touch functions can operate normally, but the common electrode signal must switch between positive and negative voltages which generates DC voltage difference and affects display
Solution Approach 1:
The patent implements dynamic voltage switching of the common electrode signal synchronized with the time-sharing driving scheme. During touch detection period, the common electrode uses negative voltage; during display period, it switches to positive voltage matching the reference signal. This dynamic adaptation enables dual functionality while eliminating the harmful DC voltage difference that would otherwise cause liquid crystal deflection.
Solution Approach 2:
The patent applies periodic switching of the common electrode signal voltage polarity according to the display/touch period division. The voltage alternates between negative (touch period) and positive (display period), with the positive voltage specifically matched to the reference signal voltage to prevent DC voltage difference. This periodic action enables time-sharing operation of display and touch functions without mutual interference.
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 prevents interference with the normal display of the touch device by maintaining a consistent electric field, ensuring accurate liquid crystal deflection and maintaining display quality during both touch and display periods.
Implementation Method 1
a display electric field is generated between the common electrode and the pixel electrode
Implementation Method 2
During the display period, a horizontal electric field generated by the ADS touch device will deflect the liquid crystal to achieve a normal display
Implementation Method 3
the common electrode is configured to load a drive signal outputted by the driving circuit to couple the common electrode and the induction electrode so as to generate a touch signal
Data Source
AI summary
Disclosed are a touch device and a driving method thereof. The touch device includes a touch screen, a detection circuit and a driving circuit, the touch screen including a common electrode, an induction electrode and a pixel electrode, the detection circuit including a first input terminal, a second input terminal and an output terminal, the first input terminal being connected with the induction electrode; during a display period, the common electrode is configured to load a common electrode signal outputted by the driving circuit, the pixel electrode is configured to load a pixel electrode signal outputted by the driving circuit, a display electric field is generated between the common electrode and the pixel electrode, the reference signal is the same as the common electrode signal. In this disclosure, no voltage difference is generated between the common electrode signal and the reference signal, and thus avoiding affecting the normal display of the touch device.