Pen Input Surface Coating Balancing Writing Feel and Sparkle
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Solution Overview
Problem
Existing pen input device surfaces with recesses and protrusions cause sparkle and lens effects on high-resolution displays, compromising image clarity and writing feel.
Innovation Solution
A surface material with concavo-convex structures having recesses and protrusions of 1.0 μm or greater and surface roughness Sa between 0.10 and 0.16 μm, combined with acrylic and silica particles, reduces lens effects and enhances writing feel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If recesses and protrusions are formed on the input surface to achieve writing feel like writing on paper, then writing feel is improved, but sparkle is generated on the display and image becomes difficult to see
Solution Approach 1:
The patent applies local quality by creating two distinct types of surface structures with different functions: large recesses and protrusions (1.0 μm or greater height) that provide writing feel, and micro recesses and protrusions (less than 1.0 μm height with Sa roughness of 0.10-0.16 μm) that reduce sparkle. Each local structure serves its specific purpose, resolving the contradiction between writing feel and sparkle prevention.
Solution Approach 2:
The surface structure is segmented into two functional layers: the primary concavo-convex structure for writing feel and the secondary micro-roughness structure for sparkle reduction. This segmentation allows each layer to independently perform its function without interfering with the other, enabling both good writing feel and reduced sparkle simultaneously.
2Object-affected harmful factors
If recesses and protrusions are minimized to reduce lens effect and prevent sparkle, then sparkle is reduced, but writing feel becomes poor
Solution Approach 1:
Instead of uniformly minimizing all surface features, the patent applies local quality by preserving large recesses and protrusions (≥1.0 μm) for writing feel while only suppressing micro-roughness features (<1.0 μm with Sa = 0.10-0.16 μm) for sparkle reduction. This selective approach maintains writing feel while preventing sparkle.
3Ease of operation
If recesses and protrusions with absolute height of 1.0 μm or greater are formed to improve writing feel, then writing feel is improved, but lens effect enlarges pixels and causes sparkle
Solution Approach 1:
The patent applies local quality by creating two distinct surface structures with different functions: large recesses and protrusions (1.0 μm or greater height) that provide writing feel, and micro recesses and protrusions (less than 1.0 μm height with Sa roughness of 0.10-0.16 μm) that reduce sparkle. Each local structure serves its specific purpose, resolving the contradiction between writing feel and sparkle prevention.
Solution Approach 2:
The patent converts the harmful lens effect into a benefit by using the micro recesses and protrusions to scatter light in a way that reduces sparkle while maintaining the writing feel provided by the larger structures. The micro-roughness layer acts as a light-diffusing element that transforms the problematic lens effect into an anti-glare property.
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
Prevents sparkle on high-resolution displays while maintaining excellent writing feel by minimizing lens effects and providing anti-glare properties.
Implementation Method 1
emitted light from the display is refracted by the recesses and protrusions on the input surface of the film
Data Source
AI summary
A surface material for a pen input device includes a base element having a sheet shape, and a coating layer covering one surface of the base element, wherein the coating layer has a concavo-convex surface disposed on a side opposite to the base element side, recesses and protrusions having an absolute height of 1.0 μm or greater as measured with a scanning white-light interference microscope are formed on the concavo-convex surface, and a value of a surface roughness Sa of the surface material in a range where the absolute height of the concavo-convex surface is less than 1.0 μm as measured with the scanning white-light interference microscope is set to a value in a range of 0.10 or greater and 0.16 or less.