Touch Sensor Insulating Layer for Flexible Display Parasitic Capacitance
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Solution Overview
Problem
In flexible display devices with on-cell type touch sensors, the presence of dams to prevent organic material drainage can lead to increased parasitic capacitance due to the thin film encapsulation layer thickness reduction, causing pixel defects and higher manufacturing costs.
Innovation Solution
A display device design featuring a substrate with a peripheral dam, a thin film encapsulation layer, and a first insulating layer with varying dielectric constants, where the first region with a lower dielectric constant is positioned between the dam and the touch sensor, reducing parasitic capacitance without increasing the encapsulation layer thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the thin film encapsulation layer is increased to reduce parasitic capacitance, then parasitic capacitance decreases, but manufacturing costs increase
Solution Approach 1:
The first insulating layer is configured with different dielectric constants in different regions: a first region with a lower dielectric constant positioned between the dam and connection wiring to reduce parasitic capacitance, and a second region with a higher dielectric constant in other areas to maintain effective capacitance for touch sensing. This local differentiation resolves the contradiction by reducing parasitic capacitance only where needed without requiring overall thickness increase.
2Reliability
If the thin film encapsulation layer thickness is increased to prevent pixel defects, then pixel defects are prevented, but the device thickness increases
Solution Approach 1:
The insulating layer between the dam and connection wiring uses a lower dielectric constant material to specifically reduce parasitic capacitance in the problematic region, preventing pixel defects without requiring increased overall encapsulation thickness. This maintains the thin form factor while achieving defect prevention.
3Reliability
If the thin film encapsulation layer thickness is increased to reduce parasitic capacitance, then parasitic capacitance decreases, but manufacturing complexity increases
Solution Approach 1:
Rather than increasing the thickness of the entire encapsulation layer structure, the invention introduces a first insulating layer with spatially varying dielectric constants. This localized approach reduces parasitic capacitance without complicating the overall encapsulation structure, as the first insulating layer is integrated into the existing encapsulation architecture.
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 minimizes parasitic capacitance and prevents pixel defects while maintaining a thin form factor suitable for flexible displays, reducing manufacturing costs by avoiding the need for thicker encapsulation layers.
Implementation Method 1
a first insulating layer between the thin film encapsulation layer and the touch sensor and having a first region and a second region, wherein a dielectric constant of the first region is lower than a dielectric constant of the second region
Data Source
AI summary
A display device includes a peripheral area around a display area, a display element in the display area, and a dam in the peripheral area. A thin film encapsulation layer covers the dam and the display element. A touch sensor is on the thin film encapsulation layer. A first insulating layer is between the thin film encapsulation layer and the touch sensor and has a first region and a second region. A dielectric constant of the first region is lower than a dielectric constant of the second region, and the first region is between the dam and the touch sensor.