Sensor Unit Edge Wiring Void Prevention
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Solution Overview
Problem
The integrated touch polarizing plate faces issues with voids forming at the edges of the flexible wiring board due to incomplete absorption by the optical adhesive, leading to display quality degradation and potential damage from bending stress, especially when using vulnerable materials like cycloolefin-based films or high-strength materials like PET.
Innovation Solution
A sensor unit design with a translucent sensor base material and a photic base material, where the flexible wiring board is joined in a wiring region closer to the edge, with an opening in the photic base material to sandwich both-side substrate ends, preventing large bending stress and void formation, and stabilizing the joint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the flexible wiring board is sandwiched between the conductive film and polarizing plate through optical adhesive, then the joint structure is formed, but voids are left at the edge of the flexible wiring board due to insufficient thickness absorption
Solution Approach 1:
The patent extracts the flexible wiring board from the sandwich structure between conductive film and polarizing plate. Instead of positioning it between the two base materials, the wiring board is joined directly to the conductive film at the edge portion, removing it from the problematic sandwich configuration that causes void formation.
Solution Approach 2:
The patent introduces a specific joining structure where the flexible wiring board is bonded to the conductive film using adhesive in a designated edge region. This intermediary joining method prevents direct contact issues between the wiring board and polarizing plate, eliminating the void formation problem while maintaining electrical connectivity.
2Manufacturing precision
If the edges of the flexible wiring board are separated from the display region to avoid voids, then void formation is prevented, but the wiring area must be widely allocated reducing display region
Solution Approach 1:
The patent applies local quality by creating a specific edge portion region on the conductive film designated for wiring board joining. This localized joining area is positioned at the extreme edge of the display region, allowing the wiring board to be connected without encroaching on the main display area, thus preventing voids while maximizing display region.
Solution Approach 2:
The patent utilizes the edge dimension of the conductive film to position the wiring board joining area. By moving the joining location to the peripheral edge region rather than the central area, the wiring connections are accommodated in a different spatial dimension that does not compromise the display region area.
3Device complexity
If the flexible wiring board is joined to a portion of the conductive film alone, then the joint is simplified, but large bending stress is generated on the conductive film when the wiring board is bent
Solution Approach 1:
The patent applies local quality by designating a specific edge portion of the conductive film for wiring board joining. This localized joining region is positioned at the edge where bending stress is naturally reduced, allowing the wiring board to be connected with minimal stress transmission to the main conductive film body, thus simplifying the joint structure while reducing bending stress.
4Adaptability or versatility
If a vulnerable material like cycloolefin-based film is used as the conductive film, then flexibility is improved, but the film may be damaged due to bending stress when the wiring board is bent
Solution Approach 1:
The patent applies local quality by positioning the wiring board joining area at the edge portion of the conductive film. This localized edge joining allows the use of flexible vulnerable materials like cycloolefin-based film in the main body while the edge region handles the mechanical stress of wiring board bending, preventing damage to the vulnerable film material.
5Reliability
If a high-strength material like PET is used as the conductive film, then durability is improved, but peeling occurs between the polarizing plate and conductive film when the wiring board is bent
Solution Approach 1:
The patent extracts the wiring board joining operation from the laminated structure between polarizing plate and conductive film. By joining the wiring board directly to the conductive film at the edge portion rather than through the laminated structure, the bending stress does not transmit to the polarizing plate-conductive film interface, preventing peeling while maintaining the integrity of the high-strength PET material.
Data Source
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AI summary
[Object] In a sensor unit in which a flexible wiring board is joined to a sensor base material, to provide a sensor unit that can prevent bubbles at an edge of the flexible wiring board from affecting a display region and can increase a strength with which the sensor base material and flexible wiring board are joined together and to provide an input device that uses the sensor unit. [Solution] A sensor base material and a photic base material 17 such as a polarizing plate are stacked together and an opening 19 is formed in the photic base material 17. Although the joining part 32 of a flexible wiring board 31 is joined to the sensor base material, a large portion of an opposing edge 32a facing a display and input region 11a, the opposing edge 32a being part of the joining part 32, is positioned in the opening 19, so bubbles along the opposing edge 32a are less likely to be generated, making the display quality of the display and input region 11a less likely to be affected. Also, since the both-side substrate ends 36 and 36 of the joining part 32 are sandwiched between the sensor base material and the photic base material 17, the joining part 32 is less likely to be deformed, making it easy to prevent damage to the sensor base material.