COF Wire Pitch Variation for Flexible Display Thermal Expansion
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Solution Overview
Problem
In flexible display devices, the uniform pitch of conventional wires connected to a driver IC on a COF film leads to misalignment and potential electric shorts when the film expands due to thermal compression, reducing the reliability of the device.
Innovation Solution
The wires on the COF are arranged into multiple sections with varying pitches and angles, ensuring non-uniform spacing to prevent misalignment and minimize the risk of electric shorts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform pitch wires are used on the COF film, then the manufacturing process is simple, but misalignment and electric shorts occur when the film expands due to thermal compression
Solution Approach 1:
The patent applies local quality by dividing the wire region into multiple sections with different pitch characteristics. The first section (near the center) has a narrower fixed pitch, while the second sections (near the edges) have wider pitches that gradually increase. This non-uniform pitch distribution compensates for thermal expansion effects locally, preventing misalignment and electric shorts while maintaining manufacturing feasibility.
2Volume of moving object
If the COF film is bent to arrange the driver IC compactly, then the device size is reduced, but the wire pitch uniformity is compromised
Solution Approach 1:
The patent changes the pitch parameter from uniform to non-uniform distribution. By setting the first section with a narrower fixed pitch and the second sections with gradually increasing wider pitches, the design accommodates the geometric distortion caused by bending the COF film, thereby maintaining connection precision despite the compact arrangement.
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 arrangement effectively prevents misalignment between the pads on the display panel and the wires on the COF, enhancing the reliability and stability of the flexible display device.
Implementation Method 1
when the film expands due to thermal compression
Data Source
AI summary
A display device includes a panel substrate including a pad region, and a COF (Chip On Film) including a wire region, the wire region including a plurality of wires connected to the pad region of the panel substrate, wherein the plurality of wires in the wire region is arranged into a plurality of sections, intervals between wires within each section being different from intervals between wires within an adjacent section, and at least one of the plurality of sections including a plurality of wires at a fixed interval.