Foldable Display Digitizer Coil Stacking for Pen Sensing Accuracy
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Solution Overview
Problem
Existing flexible display devices face challenges in manufacturing and maintaining folding reliability, particularly when incorporating digitizers that sense electromagnetic changes from pens.
Innovation Solution
A display device design featuring a digitizer with specific configurations of sensing coils, including first, second, third, and fourth sensing coils, and connector arrangements that enhance manufacturing ease and folding reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensing coils are arranged to cover the folding area for accurate pen position sensing, then measurement precision is improved, but device complexity increases due to overlapping coil layers
Solution Approach 1:
The digitizer is divided into multiple independent sensing coil layers (first layer with first and second sensing coils, second layer with third and fourth sensing coils). Each layer can be manufactured and positioned separately, reducing overall complexity while maintaining comprehensive coverage of the folding area for accurate pen position detection.
Solution Approach 2:
The patent transitions from a single-plane sensing coil arrangement to a multi-layer three-dimensional structure. By stacking sensing coils on different layers at different positions, the system achieves comprehensive coverage of the folding area without requiring a single complex planar arrangement, thus improving measurement precision while managing device complexity.
2Ease of manufacture
If connectors are placed on non-active areas for ease of connection, then ease of manufacture is improved, but device area is reduced due to connector placement constraints
Solution Approach 1:
Connectors are extracted from the active display area and relocated to non-active areas of the digitizer. This separation allows connectors to be easily accessed and connected during manufacturing without interfering with the active display region, thereby improving ease of manufacture while preserving the active area for its intended function.
3Reliability
If multiple sensing coil layers are used to cover folding area, then reliability during folding is improved, but manufacturing precision requirements increase
Solution Approach 1:
The multi-layer sensing coil structure is segmented into distinct layers that can be manufactured and positioned independently. Each layer is designed to cover specific areas, with the folding area covered by multiple layers for enhanced reliability. The segmented approach allows for standardized manufacturing processes that reduce the cumulative precision requirements compared to a single complex layer.
Solution Approach 2:
Different regions of the digitizer have different sensing coil configurations tailored to their specific requirements. The folding area receives enhanced coverage with multiple overlapping layers for improved reliability during folding operations, while non-folding areas use simpler single-layer configurations. This local optimization reduces overall manufacturing precision requirements by applying higher complexity only where needed.
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
The proposed design improves manufacturing efficiency and enhances folding reliability of flexible display devices by optimizing the digitizer's coil layout and connector connections.
Implementation Method 1
The digitizer may identify a position of a pen by sensing an electromagnetic change that occurs as the pen approaches the display device
Data Source
AI summary
A display device includes: a display panel including a first non-folding area, a folding area, and a second non-folding area along a first direction; and a digitizer under the display panel, and having an active area and a non-active area around the active area, the digitizer including: a first sensing coil in the active area; a second sensing coil in the active area, and overlapping with the folding area; a third sensing coil under the first sensing coil, and overlapping with the second non-folding area; and a fourth sensing coil under the third sensing coil, and overlapping with the first non-folding area. The third sensing coil and the fourth sensing coil do not overlap with each other in a plan view.