Guard Layer Touch Sensor Parasitic Capacitance Reduction
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Solution Overview
Problem
In touch screen display devices, the integration of touch sensors and sensor signal lines with driving signal lines leads to parasitic capacitance, causing image quality deterioration and reduced touch sensitivity due to interference, especially when these components overlap.
Innovation Solution
Positioning the touch sensor and sensor signal line either above or below the driving signal line, and using a guard layer with a driving signal similar to the touch sensor's signal to reduce parasitic capacitance, while also forming multiple sensor signal lines to ensure touch signal detection even if one line disconnects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If touch sensors and sensor signal lines are integrated with driving signal lines in the display device, then the manufacturing cost is reduced and productivity is improved, but parasitic capacitance is generated causing image quality deterioration and reduced touch sensitivity
Solution Approach 1:
The patent applies dimensional separation by positioning touch sensors and sensor signal lines in different spatial layers relative to driving signal lines. Specifically, touch sensors are formed on the lower substrate while sensor signal lines are routed on the upper substrate, creating vertical separation that reduces parasitic capacitance interference while maintaining planar integration benefits
Solution Approach 2:
The patent introduces a guard layer as an intermediary component between touch sensors and driving signal lines. This guard layer, positioned between the sensor signal lines and driving signal lines, acts as a shielding element that reduces electromagnetic interference and parasitic capacitance effects, thereby protecting touch signal integrity
2Device complexity
If touch sensors and sensor signal lines are positioned to overlap with driving signal lines, then device complexity is reduced, but parasitic capacitance increases significantly causing touch signal detection failure
Solution Approach 1:
The patent resolves the overlap problem by transitioning from horizontal proximity to vertical separation. Touch sensors remain on the lower substrate while sensor signal lines are routed on the upper substrate, creating vertical distance that eliminates significant parasitic capacitance while maintaining planar layout simplicity
Solution Approach 2:
A guard layer is introduced as a mediating structure between the sensor signal lines on the upper substrate and driving signal lines on the lower substrate. This intermediate layer provides electromagnetic shielding that prevents parasitic capacitance formation while allowing the simple overlapping layout to be maintained
3Manufacturing precision
If sensor signal lines are formed with single line configuration, then manufacturing precision requirements are reduced, but signal detection reliability decreases due to potential disconnection
Solution Approach 1:
The patent applies segmentation by dividing the sensor signal path into multiple parallel signal lines instead of using a single line. This redundancy ensures that if one signal line becomes disconnected, other lines can still transmit touch signals, thereby improving system reliability without significantly increasing manufacturing complexity
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 prevents the observation of signal lines in the display device, minimizes interference, and enhances touch signal detection stability, improving the yield and reducing resistance in sensor signal lines.
Implementation Method 1
a physical parasitic capacitance is generated, and a magnitude of the parasitic capacitance is significantly large, such that touch sensitivity is deteriorated
Data Source
AI summary
Disclosed herein are a display device having an embedded touch screen capable of preventing deterioration of image quality generated in the display device when a touch sensor and a sensor signal line are disposed in the display device and solving a problem that sensitivity of a detected touch signal is weakened due to a parasitic capacitance generated between the touch sensor and the sensor signal line and a driving signal line and components of the display device, and a method of manufacturing the same.