Touch Panel With Inverted Dome Shape For Capacitance Uniformity
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Solution Overview
Problem
Conventional touch panels with convex upper surfaces and flat lower surfaces on electronic devices lead to uneven thicknesses, causing errors in capacitance changes when operated, making them cumbersome and prone to operational errors due to different electric capacitances at the center and peripheral portions.
Innovation Solution
A touch panel design featuring a transparent plate with a concave lower surface and stacked substrates with conductive layers, where the lower surface has a dome shape in one direction and is straight in another, ensuring constant thickness and easy bonding of substrates, reducing capacitance errors and enhancing operational reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the transparent plate has a convex upper surface and flat lower surface, then the touch panel has a dome-shaped appearance, but the thickness becomes uneven causing capacitance errors
Solution Approach 1:
Instead of making the upper surface convex with a flat lower surface (conventional design), the patent inverts the approach by making the lower surface convex and the upper surface flat. This inversion resolves the capacitance uniformity issue while maintaining the dome-shaped appearance from the front view.
Solution Approach 2:
The patent applies different surface characteristics to different locations: the upper surface is kept flat for uniform capacitance distribution, while the lower surface is made convex to provide the desired dome-shaped appearance and structural support.
2Shape
If the transparent plate has uneven thickness, then the dome shape is achieved, but operational errors increase due to varying capacitance
Solution Approach 1:
The patent inverts the conventional design by placing the convex shape at the lower surface rather than the upper surface. This allows the touch panel to maintain its dome-shaped appearance while ensuring uniform thickness and capacitance distribution across the upper surface, thereby improving operational reliability.
3Shape
If the lower surface is curved, then bonding becomes difficult, but a straight lower surface causes thickness variation
Solution Approach 1:
The patent applies the convex curvature to the lower surface while keeping the upper surface flat, which is the inverse of the conventional approach. This inversion allows the straight upper surface to maintain uniform thickness for accurate capacitance measurement, while the curved lower surface provides the desired aesthetic appearance.
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
The design allows for reliable and error-free operation by maintaining constant capacitance across the touch panel surface, reducing manufacturing complexity and operational errors, and enabling easy assembly without gaps or wrinkles.
Implementation Method 1
an electric capacitance between upper conductive layer 2 and lower conductive layer 5 changes at a touched position
Data Source
AI summary
A touch panel includes a transparent plate, an upper substrate having an upper surface situated on a lower surface of the transparent plate and stacked on the transparent plate in a downward direction, an upper conductive layer provided between the lower surface of the transparent plate and the lower surface of the upper substrate, a lower substrate having an upper surface situated on the lower surface of the upper substrate and stacked on the upper substrate in the downward direction, and a lower conductive layer provided between the lower surface of the upper substrate and the upper surface of the lower substrate and facing the upper conductive layer across the upper substrate. The upper surface of the transparent plate has a dome shape projecting upward on a cross section in a first direction perpendicular to the downward direction and on a cross section in a second direction perpendicular to the downward direction and the first direction. The lower surface of the transparent plate is concave upward on the cross section in the first direction is straight on the cross section in the second direction. The touch panel can be easily manufactured and reliably operated.