Touch Sensor-Integrated Display Bezel Capacitance Compensation
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Solution Overview
Problem
Touch sensor-integrated type display devices face challenges in maintaining touch accuracy and linearity, especially at the edge and corner areas, due to reduced capacitance changes and increased parasitic capacitance, which affects performance and bezel area thickness.
Innovation Solution
The design includes a bezel area with extended touch electrodes that operate as a single touch electrode, connected through switching elements to compensate for capacitance and prevent parasitic capacitance generation, improving touch performance and reducing bezel area thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If touch electrodes are extended into the bezel area to improve touch accuracy at edge and corner areas, then touch precision is improved, but parasitic capacitance increases causing display failures
Solution Approach 1:
The touch electrode array is divided into two distinct groups: first touch electrodes disposed only in the active area, and second touch electrodes disposed in the bezel area. This segmentation allows independent control and connection of the two groups, enabling the system to connect them during touch operations to improve edge/corner touch accuracy while disconnecting them during display operations to eliminate parasitic capacitance interference.
Solution Approach 2:
The connection state between the first and second touch electrodes is dynamically changed based on operation mode. Switching elements (TFTs) are used to connect the two electrode groups during touch sensing operations to extend the effective sensing area for improved accuracy, and to disconnect them during display operations to prevent parasitic capacitance from causing display failures.
2Measurement precision
If touch electrodes are extended into the bezel area to compensate for capacitance changes, then touch linearity is improved, but the bezel area thickness increases
Solution Approach 1:
The touch electrodes are extended from the active area into the bezel area along the surface plane (horizontal dimension), rather than increasing the bezel thickness (vertical dimension). This allows the effective touch sensing area to be expanded for improved linearity and accuracy at edge and corner areas without increasing the physical thickness of the bezel structure.
3Reliability
If switching elements are added to connect and separate touch electrodes, then parasitic capacitance is controlled, but device complexity increases
Solution Approach 1:
The switching elements (TFTs) serve multiple functions: they act as pixel switching elements for display operations and simultaneously serve as connection elements for controlling the touch electrode groups during touch sensing operations. This multi-functionality allows the same hardware structure to manage both display stability and touch performance without requiring separate dedicated switching components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances touch accuracy and linearity at edge and corner areas, prevents display failures, and reduces the bezel area while maintaining initial capacitance levels, thereby improving overall touch performance.
Implementation Method 1
a plurality of first touch/common electrodes disposed in the active area to form a horizontal electric field along with the plurality of pixel electrodes
Implementation Method 2
determine an initial capacitance of the first touch/common electrodes and the second touch/common electrodes; connect the first outermost touch/common electrodes and the second touch/common electrodes, which are adjacent to each other, to compensate for the capacitance
Data Source
AI summary
Provided is a touch sensor-integrated type display device that includes a plurality of gate lines and data lines disposed to intersect each other; a plurality of pixel electrodes; a plurality of first touch/common electrodes disposed in an active area; a plurality of second touch/common electrodes disposed in a bezel area; a gate driver; a driver IC; and switching elements. The switching elements electrically connect the first touch/common electrodes to the the second touch/common electrodes which are adjacent to each other in response to a control signal.