Touch Circuit Common Electrode Voltage Stabilization
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Solution Overview
Problem
Capacitive touch sensing technologies face issues with parasitic capacitance, leading to decreased accuracy and potential failure in touch sensing, especially when display and touch modes are time-divided, causing incorrect sensing results and destabilization.
Innovation Solution
A touch circuit and display driver circuit that categorize common electrodes into groups and apply pre-setting dummy pulse signals before touch driving, stabilizing the voltage state and reducing parasitic capacitance effects by disregarding touch sensing data from these pulses, allowing accurate touch sensing and display driving without mode interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If display driving is performed before touch sensing in time-divided mode, then display function is achieved, but touch sensing accuracy deteriorates due to residual voltage and parasitic capacitance
Solution Approach 1:
The patent applies preliminary action by performing a pre-setting operation before touch sensing to clear residual voltage and stabilize the electrode state. Specifically, the touch electrode is driven with a predetermined voltage (e.g., GND voltage) before actual touch sensing to eliminate the influence of previous display driving, ensuring accurate touch measurement without compromising display function.
Solution Approach 2:
The patent changes the voltage parameter of the touch electrode dynamically based on the operating mode. During display mode, the electrode operates at display voltages; before touch sensing, it is switched to a predetermined voltage (GND) to reduce parasitic capacitance; during touch sensing, it returns to sensing voltages. This parameter switching resolves the contradiction between display and touch performance.
2Measurement precision
If touch sensing is performed with all common electrodes simultaneously, then touch detection capability is improved, but parasitic capacitance increases leading to sensing instability
Solution Approach 1:
The patent segments the touch sensing process into distinct phases: pre-setting phase where electrodes are stabilized individually or in groups, and sensing phase where actual touch detection occurs. By dividing the common electrodes into multiple groups and controlling their voltage states separately during pre-setting, the patent reduces mutual interference and parasitic capacitance while maintaining comprehensive touch detection capability.
3Measurement precision
If pre-setting dummy pulse signals are applied to stabilize voltage state, then touch sensing accuracy is improved, but additional operation time and complexity are introduced
Solution Approach 1:
The patent merges the pre-setting operation with the existing touch sensing workflow by integrating it into the frame timing structure. The pre-setting dummy pulse is applied during the touch sampling period or immediately before it, utilizing existing time slots rather than adding separate operations. This combining approach minimizes additional time loss while achieving voltage stabilization for accurate sensing.
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 improves touch sensing accuracy and image quality by stabilizing the sensing process, reducing parasitic capacitance, and minimizing the influence of display driving on touch mode and vice versa, enabling proper function of both touch and display modes.
Implementation Method 1
undesirable parasitic capacitance may be generated in addition to capacitance required for touch sensing
Data Source
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AI summary
A touch sensitive display device (100), and a method of driving the same. When touch driving is ended and before display driving begins to be performed, post-setting driving may be performed so as to accurately perform display driving without the influence of ended touch driving, thereby improving image quality.