Reflective Display Stacking Layout for Sub-2.5 mm Narrow Borders
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Solution Overview
Problem
Existing display devices face challenges in shrinking the border area due to the bending and bonding requirements of flexible printed circuit boards, which complicates the manufacturing of display devices with arbitrary shapes, especially in wearable applications.
Innovation Solution
A narrow border reflective display device design that stacks a TFT substrate and a driving circuit substrate, using conductive wires to connect first and second conductive pads, eliminating the need for a flexible printed circuit board connection to the TFT substrate, allowing the border width to be determined by the distance between these pads, and enabling a customized shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If flexible printed circuit board and chip on film process are used to electrically connect driving circuit and TFT substrate, then electrical connection is achieved, but border area size cannot be shrunk due to bending area and bonding pads
Solution Approach 1:
The patent divides the electrical connection function into two separate substrates: the driving circuit substrate and the TFT substrate. Each substrate independently carries its own circuit patterns and bonding pads, eliminating the need for a flexible printed circuit board to bridge them. This segmentation allows direct stacking and bonding between substrates, significantly reducing the border area while maintaining electrical connectivity.
Solution Approach 2:
The patent implements a stacked configuration where the TFT substrate is positioned directly on top of the driving circuit substrate, with one substrate nested within the overall structure of the other. This vertical integration eliminates the horizontal space required for flexible circuit boards and their bending areas, thereby shrinking the border area while preserving all necessary electrical connections.
2Adaptability or versatility
If flexible printed circuit board is used for electrical connection, then electrical connectivity is achieved, but display device shape cannot be customized due to rigid connection requirements
Solution Approach 1:
By separating the driving circuit and TFT substrate into distinct, independently designed components, the patent enables flexible layout arrangements. Each substrate can be shaped and positioned according to specific design requirements, allowing arbitrary display device shapes while maintaining reliable electrical connections through direct bonding between corresponding pads on each substrate.
Solution Approach 2:
The patent transitions from a planar, horizontally-connected architecture to a vertical, stacked architecture. This dimensional change allows the display area and connection areas to be arranged in the vertical dimension rather than consuming horizontal border space, enabling arbitrary shape customization in the planar view while maintaining connection reliability through vertical stacking and bonding.
3Area of stationary object
If conventional manufacturing method with flexible printed circuit board is used, then electrical connection is achieved, but border width is large making narrow border design difficult
Solution Approach 1:
The patent extracts and eliminates the flexible printed circuit board from the connection structure, removing the source of border area expansion. By taking out this intermediate connection component and directly bonding the driving circuit substrate to the TFT substrate, the patent achieves narrow border design while simplifying the overall connection structure despite the increased precision requirements of direct substrate bonding.
Data Source
AI summary
A narrow border reflective display device includes an driving circuit substrate, a TFT substrate, a front plane laminate, multiple conductive wires, a cover, and a glue. The TFT substrate is located on the driving circuit substrate. The TFT substrate is located between the driving circuit substrate and the front plane laminate. The conductive wires are electrically connected with the driving circuit substrate and the TFT substrate. The cover is located on the front plane laminate. The glue surrounds the driving circuit substrate, the TFT substrate, the front plane laminate, the front plane laminate, and the conductive wires.