OLED Display Architecture Using Multiplexers for Flexible Interconnects
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Solution Overview
Problem
Current display technologies for flexible and wearable applications face challenges with high-cost and unreliable interconnects, particularly due to the use of tape automated bonding (TAB) processes, which are expensive and difficult to implement on deformable substrates, leading to unreliable connections when devices are flexed.
Innovation Solution
A design architecture for OLED displays with a reduced number of external electronic connections, utilizing an analog multiplexer with transistors to connect external source lines to data lines, allowing for heat seal bonding and increasing the pitch of connections, thereby reducing costs and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If TAB processes are used to bond interconnects to the display, then high resolution data driving is achieved, but the device becomes expensive and unreliable when flexed
Solution Approach 1:
The patent segments the interconnect structure into rigid display element and flexible circuit board components, allowing each to be optimized independently. The rigid display maintains high resolution with precise interconnect spacing, while the flexible circuit board uses larger, more reliable connections that can accommodate bending stresses.
Solution Approach 2:
The patent extracts the flexible interconnect function from the rigid display element and places it on a separate flexible circuit board. This separation allows the display to maintain its rigid, high-resolution structure while the flexible circuit board handles the bending and connection functions with larger, more reliable interconnects.
2Productivity
If TAB processes are used for bonding interconnects, then data driving capability is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive TAB-bonded interconnects with a more economical flexible circuit board assembly. The flexible circuit board uses standard, lower-cost manufacturing processes and materials, sacrificing some theoretical performance for significant cost reduction while maintaining adequate functionality.
Solution Approach 2:
The patent substitutes the complex mechanical TAB bonding process with a simpler flexible circuit board attachment method. This replacement eliminates the need for precise high-resolution bonding while maintaining data driving capability through the flexible circuit's inherent flexibility and connection ability.
3Productivity
If TAB processes are used to bond interconnects, then data driving is achieved, but implementation on deformable substrates becomes difficult
Solution Approach 1:
The patent uses a flexible circuit board with flexible interconnect structures that can accommodate substrate deformation. The flexible circuit board's inherent flexibility allows it to bend and deform with the substrate without compromising electrical connections, unlike rigid TAB-bonded interconnects.
Solution Approach 2:
The patent segments the system into a rigid display element and a flexible circuit board, allowing the flexible portion to deform with the substrate while the rigid display maintains its structural integrity and high-resolution data driving capability.
4Measurement precision
If high resolution interconnects with 25 μm spacing are used, then display resolution is improved, but connection reliability when flexed deteriorates
Solution Approach 1:
The patent resolves the spacing conflict by moving from a two-dimensional planar constraint to a three-dimensional solution. The flexible circuit board can be routed at different angles and heights, allowing adequate spacing between connections while maintaining the high-resolution display's tight interconnect spacing through vertical routing and layered connections.
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 approach results in a more reliable, flexible, and cost-effective display solution with improved structural stability and longer interconnect integrity, suitable for small-sized, wearable, or rollable displays, by reducing the number of external connections and using heat seal bonding instead of TAB processes.
Implementation Method 1
an analog multiplexer comprising a plurality of transistors; wherein the number of external source connections to the display is less than half the number of data lines on the display element
Implementation Method 2
the external source connections to the device are heat seal bonded
Data Source
AI summary
Described herein are display devices having architectures with a reduced number of external connections from the display to the external electronics, which allows for an increase in the pitch of the external connections, thereby improving reliability and flexibility, and reducing costs. The architecture of these devices is based on using multiplexers to connect external source lines to the individual display column lines. Accordingly, data signals can come into the display on a reduced number of external source lines as compared to the number of display column lines. The architecture allows for high-reliability, rugged contacts to a small-sized display by avoiding the need for high resolution interconnects.