Touch Display Panel Multiplexer Bypass Trace Design
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Solution Overview
Problem
In touch display panels, the integration of a multiplexer with a shift register and touch module leads to instability in the common electrode due to external signal interference, particularly when the multiplexer is turned off, and requires more control signals as the input/output ratio increases, affecting accurate touch point detection.
Innovation Solution
The implementation of a multiplexer circuit with a bypass trace reduces the number of control signals needed, minimizing the influence of these signals on the touch module by coupling switches between source lines and a source driver, thereby enhancing the stability and accuracy of touch point detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a multiplexer is integrated into the display panel to reduce component count, then device complexity is reduced, but the number of control signals increases affecting touch module accuracy
Solution Approach 1:
The multiplexer circuit is divided into multiple independent multiplexers, each handling a subset of source lines. This segmentation reduces the control signal requirement for each individual multiplexer, thereby minimizing interference with the touch module while maintaining the overall integration benefit
Solution Approach 2:
A bypass trace is introduced as an intermediary pathway that allows certain source lines to connect directly to the source driver without passing through the multiplexer switches. This mediator approach reduces the number of control signals needed while maintaining signal integrity
2Productivity
If the input/output ratio of the multiplexer increases to handle more source lines, then productivity is improved, but the number of control signals increases affecting touch module stability
Solution Approach 1:
Instead of using a single multiplexer with high input/output ratio, the system segments the source lines into multiple groups, each handled by a separate multiplexer. This reduces the control signal burden on each multiplexer and minimizes interference with the touch module, maintaining reliability while achieving high productivity through parallel processing
Solution Approach 2:
The bypass trace introduces an additional dimensional pathway (direct connection) alongside the conventional multiplexer switching path. This dimensional change allows certain signals to bypass the control signal overhead, reducing interference with the touch module while maintaining high source line handling capacity
3Use of energy by moving object
If the multiplexer is turned off to reduce power consumption, then use of energy is improved, but the data line enters floating state causing common electrode instability
Solution Approach 1:
The bypass trace ensures continuous electrical connection between the source driver and certain source lines, maintaining the data line in a stable state even when the multiplexer is turned off. This continuous pathway prevents the floating state while allowing the multiplexer to be powered down, achieving both energy savings and voltage stability
Data Source
AI summary
A touch display panel includes a pixel array, a touch module, and a multiplexer circuit. The pixel array includes a plurality of pixels, a plurality of gate lines, and a plurality of source lines. The pixels are electrically coupled to the source lines and the gate lines. The touch module and the pixel array are overlapped. The multiplexer circuit is coupled between all of the source lines and a source driver and has a plurality of multiplexers. The multiplexers are respectively coupled to n source lines and respectively include a plurality of switches and a bypass trace. The switches are respectively coupled between the first source line to the (n−1)th source line of the n source lines and the source drivers. The bypass trace is coupled between the nth source line of the n source lines and the source driver.