Bent Substrate Touch Sensor Pad Alignment
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Solution Overview
Problem
In display devices with touch screens, variations in the size of conductive balls used for connecting the touch screen and signal input terminals can lead to contact failures due to increased size, causing reliability issues.
Innovation Solution
A display device design featuring a second substrate with a touch sensor and touch pad that is bent to align with connection pads, using conductive balls or adhesive layers for electrical connection, and optionally including elastic members or polarizing layers to maintain the bent shape and improve contact reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the distance between the touch screen and the substrate is increased, then the connection reliability is improved, but the size of the conductive ball must increase causing variation and contact failure
Solution Approach 1:
The patent divides the connection structure into multiple segments: the conductive ball is separated from the touch screen and substrate by introducing a recess structure. The conductive ball is disposed in the recess, which is formed between the touch screen and the substrate, thereby segmenting the connection path and allowing the conductive ball to maintain a small size while still achieving reliable electrical connection across the gap.
Solution Approach 2:
The patent introduces a vertical dimension by forming a recess structure that extends downward from the touch screen surface. This creates a multi-level connection architecture where the conductive ball is positioned in the recess, effectively utilizing the vertical space to reduce the horizontal footprint and size variation of the conductive ball while maintaining adequate connection distance.
2Length of stationary object
If the conductive ball size is increased to match the distance, then the connection distance is covered, but the variation in size increases causing contact failure
Solution Approach 1:
The patent applies local quality by creating a recess structure with specific dimensional characteristics tailored to the connection requirements. The recess provides a localized environment that constrains the conductive ball, ensuring consistent positioning and electrical contact without requiring the conductive ball itself to be large. This local structural modification improves manufacturing precision while maintaining adequate connection distance coverage.
3Reliability
If the touch screen is spaced apart from the substrate, then the touch sensor performance is improved, but the conductive ball size variation increases
Solution Approach 1:
The patent implements preliminary action by pre-forming the recess structure in the substrate or support layer before disposing the conductive ball. This pre-prepared recess structure provides a defined space that guides and constrains the conductive ball, ensuring uniform positioning and reducing size variation. The recess acts as a pre-configured solution that stabilizes the conductive ball placement while allowing adequate spacing for touch sensor performance.
Data Source
AI summary
A display device includes: a first substrate including a display area including a pixel area and a non-display area adjacent to the display area, the first substrate including a connection pad disposed in the non-display area; and a second substrate opposite to the first substrate, the second substrate including a base substrate including a sensing area corresponding to the display area and a non-sensing area corresponding to the non-display area, and a touch sensor disposed on the base substrate, wherein the touch sensor includes a touch sensing electrode disposed in the sensing area, a touch pad disposed in the non-sensing area, and a sensing line electrically connecting the touch sensing electrode and the touch pad, wherein the non-sensing area of the second substrate is bent such that the connection pad and the touch pad are opposite to each other.