Touch Display Panel Auxiliary Switch Circuit for Parasitic Capacitance Reduction
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Solution Overview
Problem
Touch display panels with self-capacitance mode require numerous wires and a large control chip, leading to increased size and parasitic capacitance when touch sensing electrodes overlap with pixel arrays, reducing sensitivity.
Innovation Solution
A touch display panel design incorporating a touch circuit, touch electrode layer, multiplexers, and a switch circuit that outputs touch sensing and guarding signals using control signals to reduce wire count and capacitance loading, with the switch circuit configured to minimize charging time and resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If touch sensing electrodes are arranged to overlap with the pixel array, then the display area is maximized, but parasitic capacitance increases and touch sensitivity decreases
Solution Approach 1:
The touch sensing electrode is divided into multiple segments (first touch sensing electrode and second touch sensing electrode) that are arranged in different layers. This segmentation allows the electrodes to overlap with the pixel array while reducing parasitic capacitance through the intermediate layer structure, thus maintaining display area without sacrificing touch sensitivity
Solution Approach 2:
The patent transitions from a planar arrangement to a three-dimensional layered structure by placing touch sensing electrodes in different layers (first and second touch sensing electrode layers). This dimensional change enables the electrodes to overlap with the pixel array in the vertical direction while maintaining electrical isolation through the intermediate layer, thereby maximizing display area without increasing parasitic capacitance
2Measurement precision
If numerous wires are used to connect touch sensing electrodes in self-capacitance mode, then touch sensitivity is maintained, but the control chip size and wire count increase
Solution Approach 1:
Multiple touch sensing electrodes are electrically connected and merged into a single common electrode structure. This merging reduces the number of separate wire connections needed while maintaining touch sensitivity through the combined capacitive effect of all electrode segments, thus reducing control chip size without sacrificing measurement precision
Solution Approach 2:
The touch sensing electrode structure serves multiple functions: it acts as both the display pixel array and the touch sensing element, and the segmented electrodes can be selectively activated. This multi-functionality reduces the need for separate control circuits for each electrode, thereby reducing control chip size while maintaining touch sensitivity
Data Source
AI summary
A touch display panel includes a touch circuit, a touch electrode layer and a plurality of multiplexers. The touch electrode layer includes a plurality of first electrodes. Each of the multiplexers is electrically connected to the touch circuit and the first electrodes. Each of the multiplexers is configured to output a touch sensing signal, a first guarding signal and a second guarding signal according to a first guarding control signal, a second guarding control signal, a first touch control signal, and a second touch control signal.