Touch Display Local Buffer Driving Circuit Noise Reduction
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Solution Overview
Problem
Touch display devices face issues with deteriorated touch sensitivity and noise due to display driving, particularly because of time-divisional driving methods that are insufficient for both image quality and touch sensitivity, leading to compromised performance in high-resolution displays.
Innovation Solution
The implementation of a touch display device with a driving circuit that includes local buffers for each common electrode column, allowing for simultaneous display driving and touch driving by modulating the common signal and ground voltage, thereby reducing noise interference between touch electrode columns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If time-division driving method is used to separate display driving and touch driving, then both functions can be performed, but touch sensitivity deteriorates and image quality is compromised
Solution Approach 1:
The common electrode columns are divided into multiple groups, with each group driven by a separate common electrode driving circuit. This segmentation allows different groups to be driven at different times or with different signals, enabling simultaneous display and touch sensing operations without mutual interference, thus resolving the contradiction between dual-function capability and touch sensitivity
Solution Approach 2:
The patent implements periodic switching between display driving and touch sensing operations across different electrode groups. By cycling through different groups in a periodic manner, the system maintains both display and touch functions while ensuring each group has dedicated time for sensing, preventing sensitivity deterioration
2Adaptability or versatility
If time-division driving is used to separate display and touch operations, then both functions can be implemented, but image quality deteriorates due to insufficient display driving time
Solution Approach 1:
By segmenting the common electrode columns into multiple groups with independent driving circuits, the system can perform display driving on one group while simultaneously performing touch sensing on another group. This parallel operation through segmentation ensures sufficient display driving time is allocated to each group, maintaining high image quality while enabling touch functionality
Solution Approach 2:
The patent ensures continuous display driving by maintaining display operations on electrode groups that are not currently being used for touch sensing. This continuity principle ensures that display driving never stops, preserving image quality while touch sensing occurs on alternative groups
3Device complexity
If common signal is supplied to all common electrode columns simultaneously, then circuit complexity is reduced, but noise from display changes affects all touch electrode columns
Solution Approach 1:
The common electrode columns are segmented into multiple groups, each with its own common electrode driving circuit. This segmentation isolates noise from display changes to only affect the currently active display group, while other groups can perform touch sensing without interference. The increased number of driving circuits is offset by the reduced signal distribution complexity
Solution Approach 2:
Each common electrode group receives a locally optimized common signal from its dedicated driving circuit, allowing the signal characteristics to be tailored to the specific needs of that group. This local quality approach enables noise reduction for sensing groups while maintaining optimal drive signals for display groups, resolving the contradiction between circuit complexity and noise interference
Data Source
AI summary
A touch display device includes a display panel having a plurality of data lines, gate lines, and common electrodes, a data driving circuit supplying a data signal to the data lines, a common electrode driving circuit supplying a common signal to the common electrodes and outputting sensing data by detecting sensing signals from one or more of the common electrodes, and a touch controller sensing touch based on the sensing data, in which the common electrodes are arranged in two or more common electrode columns, the two or more common electrode columns each include two or more common electrodes, and while the data signal is supplied to the data lines, the two or more common electrode columns are supplied with a common signal respectively through local buffers. It is possible to perform touch sensing even while display driving by removing noise due to display driving.