Flexible Circuit Cover Layer for Stable Touch Sensing
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Solution Overview
Problem
Display devices experience issues with sensing reliability due to parasitic capacitance fluctuations and ghost touch phenomena, which affect the accuracy of touch-based inputs.
Innovation Solution
The display device incorporates a flexible circuit film with a conductive pattern and a cover layer, where one conductive layer is stably grounded to maintain constant parasitic capacitance and another is connected to the sensor controller to detect delamination, thereby improving sensing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional input sensor structure is used, then the device structure is simple, but parasitic capacitance fluctuations cause ghost touch phenomena and reduced sensing reliability
Solution Approach 1:
The cover layer is divided into multiple conductive layers (first conductive layer and second conductive layer) with different functions. The first conductive layer is connected to the first conductive pattern for signal transmission, while the second conductive layer is connected to the second conductive pattern receiving reference voltage, separating the signal path from the reference voltage path to stabilize parasitic capacitance.
Solution Approach 2:
The first insulating layer is introduced as an intermediary between the first conductive layer and the second conductive layer, electrically isolating them while maintaining their spatial relationship. This intermediary structure prevents direct electrical interference between the signal-carrying first conductive layer and the reference voltage-carrying second conductive layer, stabilizing the electrical environment for accurate touch sensing.
2Reliability
If conductive layers are added to stabilize parasitic capacitance, then ghost touch is prevented, but manufacturing complexity increases
Solution Approach 1:
The first conductive layer, second conductive layer, and first insulating layer are integrated into a single cover layer structure that is formed and attached as one unit. This merging of multiple functional layers into a single manufacturable component simplifies the assembly process while maintaining the electrical stabilization benefits of having separate conductive layers with insulating separation.
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 ghost touches and allows for the detection of defective products during manufacturing, enhancing the overall reliability of touch sensing in display devices.
Implementation Method 1
a first insulating layer disposed between the first conductive layer and the second conductive layer
Implementation Method 2
a conductive adhesive layer disposed between the cover layer and the flexible circuit film to electrically connect the first conductive pattern to the first conductive layer or to electrically connect the second conductive pattern to the second conductive layer
Implementation Method 3
One conductive layer of the cover layer is electrically connected to the conductive pattern applying the reference voltage to be stably grounded. Thus, a parasitic capacitance between the signal lines and the conductive layer of the cover layer is maintained at a constant level
Data Source
AI summary
A display device includes a display module, a flexible circuit film, a sensor controller, and a cover layer. The display module includes a display panel and an input sensor including a sensing electrode. The flexible circuit film includes a first conductive pattern, a second conductive pattern receiving a reference voltage, and a signal line electrically connected to the sensing electrode. The sensor controller is electrically connected to the signal line and the second conductive pattern and is disposed on the flexible circuit film. The cover layer is disposed on the flexible circuit film and includes a first conductive layer electrically connected to the first conductive pattern and overlapping the signal line, a second conductive layer disposed on the first conductive layer, electrically connected to the second conductive pattern, and overlapping the signal line, and a first insulating layer disposed between the first conductive layer and the second conductive layer.