Touch Screen Lead Line Capacitance Offset Compensation
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Solution Overview
Problem
Projected capacitive touch panels experience detection errors due to offset electrostatic capacitance and uneven detection sensitivity caused by parasitic capacitance between lead lines and display modules, such as LCDs, which complicates accurate touch position determination.
Innovation Solution
Incorporating additional capacitors in the mounting region of the touch screen to adjust electrostatic capacitance, specifically by providing potential fixed terminals and mounting terminal electrodes that create additional capacitors to equalize electrostatic capacitance values among lead lines, thereby reducing offset and uneven sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a touch panel is mounted on an LCD with a front frame, then the touch panel can be integrated with a display module, but capacitive coupling between outermost lead lines and the front frame increases, causing electrostatic capacitance offset
Solution Approach 1:
The patent applies preliminary anti-action by introducing additional capacitors connected to outermost lead lines before the capacitive coupling with the front frame occurs. These capacitors pre-compensate for the excessive parasitic capacitance by providing an opposing capacitive effect, thereby canceling out the harmful capacitive coupling and maintaining uniform electrostatic capacitance across all lead lines
Solution Approach 2:
The patent changes the capacitance parameter by adding external capacitors with specific capacitance values to the outermost lead lines. This parameter modification compensates for the increased parasitic capacitance caused by the front frame, adjusting the total capacitance to match the uniform capacitance level of inner lead lines
2Stability of the object's composition
If outermost lead lines have larger capacitive coupling with the front frame, then the structural integration is maintained, but the dynamic range of the controller is reduced and detection sensitivity is degraded
Solution Approach 1:
The patent modifies the capacitance parameter of outermost lead lines by adding external capacitors, changing the total capacitance value to compensate for excessive parasitic capacitance. This parameter change restores the dynamic range of the controller and improves detection sensitivity while maintaining structural integration
Solution Approach 2:
The patent applies preliminary action by pre-adjusting the capacitance of outermost lead lines through external capacitors before touch detection operations begin. This preliminary capacitance adjustment ensures that the controller operates within its optimal dynamic range and maintains high detection sensitivity throughout operation
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 solution effectively reduces electrostatic capacitance offset and enhances detection sensitivity by ensuring uniform capacitance values across all lead lines, improving the accuracy of touch position detection.
Implementation Method 1
additional capacitors that are provided in a mounting region in which mounting terminals of a plurality of lead lines, each of which is connected to one of the column-direction wirings or one of the row-direction wirings, are mounted, and are configured to apply electrostatic capacitance to the plurality of lead lines
Data Source
AI summary
A touch screen includes column-direction wirings extending in a column direction, row-direction wirings extending in a row direction orthogonal to the column direction, and detection cells provided in areas in which the column-direction wirings and the row-direction wirings are three-dimensionally intersect with each other. The touch screen further includes additional capacitors that are provided in a mounting region in which mounting terminals of a plurality of lead lines, each of which is connected to one of the column-direction wirings or one of the row-direction wirings, are mounted, and are configured to apply electrostatic capacitance to the plurality of lead lines, and at least one potential fixed terminal configured to fix a potential of one electrode of each of the additional capacitors.