Shift Register Signal Separation for Touch Display Interference
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Solution Overview
Problem
In existing touch display panels, driving signals and touch signals interfere with each other, affecting the touch function.
Innovation Solution
A shift register with a pull-up unit, pull-down unit, and output unit, where the second signal terminal acts as a switching terminal to separate touch signals from driving signals during transmission, ensuring the touch signal is transmitted without interference and the driving signal continues to scan afterwards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single shift register is used for both driving signal transmission and touch signal transmission, then the device complexity is reduced, but the driving signal and touch signal interfere with each other affecting touch function
Solution Approach 1:
The patent divides the signal transmission function into two separate shift registers: one dedicated to driving signals and another dedicated to touch signals. This segmentation eliminates mutual interference between the two signal types while maintaining separate transmission paths, thus preserving touch function reliability without excessive complexity increase.
Solution Approach 2:
The patent extracts the touch signal transmission function from the driving signal transmission path by providing a dedicated touch signal shift register. This separation removes the interfering factor (driving signal) from the touch signal path, ensuring reliable touch detection while maintaining overall system functionality.
2Reliability
If separate shift registers are used for driving signals and touch signals, then signal interference is eliminated, but the device complexity increases
Solution Approach 1:
The patent merges the control logic and operational mechanisms of the two shift registers, allowing them to share common control circuits and timing mechanisms. This merging approach enables separate signal transmission paths while avoiding proportional increases in overall device complexity, as the two registers can be controlled in a coordinated manner.
Solution Approach 2:
The patent designs the shift register system with universal control mechanisms that can manage both driving signal transmission and touch signal transmission. The control logic is made multi-functional to handle both signal types, reducing the need for separate dedicated control circuits and thereby limiting the increase in device complexity.
3Reliability
If the second signal terminal is used as a switching terminal to separate touch and driving signals, then signal interference is prevented, but the control complexity increases
Solution Approach 1:
The patent implements periodic switching at the second signal terminal to alternately connect the touch signal shift register and driving signal shift register to the common output node. This periodic action is controlled by timing signals that coordinate with the scanning periods, allowing signal separation without requiring complex continuous control mechanisms.
Solution Approach 2:
The patent uses preliminary timing control to pre-establish the switching state of the second signal terminal before signal transmission begins. The switching terminal is predetermined to be in a specific state based on the current operation mode (touch detection or display driving), simplifying the control logic by avoiding dynamic decision-making during signal transmission.
Data Source
AI summary
The present invention discloses a shift register for a touch display panel and a driving method thereof, a driving circuit and a display apparatus. The shift register includes a pull-up unit, a pull-down unit and an output unit, the pull-up unit controls a potential of the pull-up node according to input signals of the input terminal, the second signal terminal and the reset terminal and a potential of the pull-down node, the pull-down unit controls the potential of the pull-down node according to an input signal of the first signal terminal and the potential of the pull-up node, and the output unit controls an output signal of the output terminal according to the input signals of the first signal terminal and the second signal terminal and the potentials of the pull-down node and the pull-up node.