Touch Display Driving Circuit Modulation for Parasitic Capacitance
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Solution Overview
Problem
Existing driving circuits for touch display panels struggle to provide load-free driving functions during touch periods, as they are designed to maintain constant voltage levels, which is inadequate for overcoming parasitic capacitances in in-cell touch sensors.
Innovation Solution
The proposed driving circuit incorporates a controller, diodes, and capacitors to generate modulation signals that toggle the high and low gate output signals, allowing them to swing above and below original DC levels, enabling load-free driving without modifying the internal structure of the power integrated circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the driving circuit maintains constant voltage levels during display periods, then stable display performance is achieved, but the circuit cannot overcome parasitic capacitances during touch periods
Solution Approach 1:
The driving circuit dynamically switches between two operational modes: during display periods, it maintains constant voltage levels for stable display performance; during touch periods, it generates toggling signals that swing above and below original DC levels to overcome parasitic capacitances. This dynamic adaptation resolves the contradiction between display stability and touch sensing capability.
Solution Approach 2:
The circuit changes the voltage level parameters of control signals based on operational mode. During display periods, voltage levels remain constant; during touch periods, voltage levels are modulated to swing above and below original DC levels. This parameter change enables the circuit to achieve both stable display performance and effective touch sensing.
2Adaptability or versatility
If modulation signals are generated to enable load-free driving during touch periods, then parasitic capacitances are overcome, but the power integrated circuit structure remains unchanged
Solution Approach 1:
The driving circuit is segmented into functional modules: a controller for generating modulation signals, diodes for signal direction control, and capacitors for voltage level modulation. This segmentation allows the load-free driving function to be achieved through external components without modifying the internal structure of the power integrated circuit, reducing device complexity while maintaining adaptability.
Solution Approach 2:
External components (controller, diodes, capacitors) act as intermediaries between the power integrated circuit and the touch display panel. These intermediaries generate and condition modulation signals that enable load-free driving during touch periods without requiring any modification to the power integrated circuit's internal structure.
3Adaptability or versatility
If control signals are adjusted into varying voltage levels for touch sensing, then parasitic capacitances are compensated, but fixed voltage levels required for display function are lost
Solution Approach 1:
The driving circuit employs periodic action by switching between display mode and touch mode operations. During display periods, control signals maintain fixed voltage levels for stable display function. During touch periods, the same control signals are periodically modulated with varying voltage levels to compensate for parasitic capacitances. This periodic alternation allows the system to achieve both voltage level adjustment for touch sensing and display function stability.
Data Source
AI summary
A driving circuit, for driving a touch display panel, includes a controller, a first diode, a first capacitor, a second diode and a second capacitor. The controller is configured to provide a first modulation signal and a second modulation signal. The first diode is coupled between a power integrated circuit and a first node for providing a low gate output signal to the touch display panel. The first capacitor is coupled between the controller and the first node. The second diode is coupled between the power integrated circuit and a second node for providing a high gate output signal to the touch display panel. The second capacitor is coupled between the controller and the second node. During a touch period, the controller is configured to provide the first modulation signal with toggling voltage levels, and provide the second modulation signal with toggling voltage levels.