Touch Display Timing Control for Lower Parasitic Capacitance
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Solution Overview
Problem
Existing touch display devices face challenges in achieving improved display quality while maintaining touch sensitivity, as the integration of touch and display periods can lead to parasitic capacitance and reduced sensitivity due to potential differences in voltage levels during these periods.
Innovation Solution
A touch display device is designed with a time-divided approach, where the touch period and display period are separated, utilizing a display controller to generate synchronization signals, a gate driving circuit to manage gate voltages, and a touch power circuit to apply pulse width modulation signals, ensuring that the touch electrodes operate with a voltage level distinct from the display period, thereby minimizing parasitic capacitance and enhancing sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If touch sensing function is integrated with display function in a single device, then the device provides convenient touch input capability, but parasitic capacitance interference occurs during touch periods that degrades display quality
Solution Approach 1:
The patent segments the operating cycle into distinct touch periods and display periods. During touch periods, touch electrodes are activated for sensing while display is suspended. During display periods, touch electrodes are deactivated and display operates normally. This temporal segmentation eliminates parasitic capacitance interference by ensuring touch and display operations do not occur simultaneously.
Solution Approach 2:
The patent implements periodic switching between touch sensing mode and display mode. A control circuit periodically generates touch synchronization signals that activate touch electrodes during designated touch periods, then deactivates them during display periods. This periodic action creates a rhythm that allows both functions to operate effectively without mutual interference.
2Measurement precision
If touch electrodes are activated during touch periods, then touch sensing function is enabled, but voltage differences and parasitic capacitance affect display quality
Solution Approach 1:
The patent extracts the harmful parasitic capacitance effect by removing touch electrode activation during display periods. The control circuit selectively deactivates touch electrodes when display operation is required, eliminating the source of parasitic capacitance interference. This extraction allows display quality to be maintained while preserving touch sensing capability during dedicated touch periods.
Solution Approach 2:
The patent applies preliminary anti-action by preemptively deactivating touch electrodes before display periods begin. The control circuit anticipates the need to eliminate parasitic capacitance and switches touch electrodes to an inactive state in advance, preventing interference before it can occur. This proactive approach ensures clean display operation without residual capacitance effects.
3Measurement precision
If time-divided driving method is used to separate touch period and display period, then parasitic capacitance is reduced and sensitivity is improved, but device complexity increases due to additional control circuits
Solution Approach 1:
The patent implements multi-functionality by designing a control circuit that simultaneously manages both touch sensing operations and display operations through a unified timing mechanism. The same control circuit generates control signals for gate driving circuits during display periods and touch synchronization signals for touch electrode activation during touch periods. This universal control approach reduces overall device complexity despite the sophisticated time-divided operation.
Solution Approach 2:
The patent merges the control functions for touch and display operations into an integrated control system. The control circuit combines touch synchronization signal generation with display timing control, and the gate driving circuit handles both display scanning and touch electrode activation. This merging of functions reduces the number of separate control circuits needed, thereby reducing device complexity while maintaining the benefits of time-divided operation.
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 solution allows for improved display quality and touch sensitivity by eliminating unnecessary parasitic capacitance, ensuring that the touch electrodes function effectively without interfering with the display process, resulting in a more responsive and clear user interface.
Implementation Method 1
a touch power circuit configured to output a voltage that is generated based on the pulse width modulation signal
Implementation Method 2
a gate driving circuit configured to receive a high-level gate voltage and the control signal, and generate and output a gate voltage pulse according to the high-level gate voltage and the control signal
Implementation Method 3
a display controller configured to generate and output a first touch synchronization signal and a control signal, the first touch synchronization signal defining a display period and a touch period
Implementation Method 4
ensuring that the touch electrodes operate with a voltage level distinct from the display period, thereby minimizing parasitic capacitance and enhancing sensitivity
Data Source
AI summary
A touch display device includes a display controller configured to output a control signal and a first touch synchronization signal defining a display period and a touch period, a gate driving circuit configured to receive a high-level gate voltage and the control signal, and output a gate voltage pulse, a display panel comprising gate lines to which the gate voltage pulse is input and sub-pixels, a touch controller configured to receive the first touch synchronization signal, and output a pulse width modulation signal, and a touch power circuit configured to output a voltage generated based on the pulse width modulation signal to the gate driving circuit in at least a first period of the touch period, and output the high-level gate voltage to the gate driving circuit based on a second touch synchronization signal that defines a pseudo display period in a second period of the touch period.