Writing Feel Improving Sheet Friction Control
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Solution Overview
Problem
Current writing feel improving sheets for touch panels do not adequately replicate the writing experience of using a ballpoint pen, as they fail to achieve the desired frictional force and vibration when used with a touch pen.
Innovation Solution
A writing feel improving sheet with a base material and a writing feel improving layer that, when contacted by a touch pen, exhibits a specific range of frictional force differences and standard deviations, mimicking the writing experience on paper, including a difference between maximum and minimum frictional force of 80 mN to 300 mN and a standard deviation of 15 mN to 60 mN, and an average frictional force of 200 mN to 1200 mN.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a writing feel improving film with curable resin and leveling agent is used, then the surface smoothness is improved, but the writing feel reproduction of ballpoint pen is insufficient
Solution Approach 1:
The invention changes the friction coefficient parameters by introducing a specific roughness structure with controlled peak-to-valley height (0.1-10 μm) and peak spacing (10-100 μm). This parameter change transforms the surface from overly smooth to having controlled micro-irregularities that replicate ballpoint pen writing feel while maintaining touch panel functionality
Solution Approach 2:
The invention applies local quality by creating specific micro-roughness features (peaks and valleys) distributed across the surface. These localized structural variations provide the friction characteristics of ballpoint pen writing while the overall surface remains smooth enough for touch panel operation
2Ease of operation
If the friction coefficient is reduced for smooth writing, then the writing smoothness is improved, but the vibration feeling is lost
Solution Approach 1:
The invention optimizes friction parameters by controlling the roughness structure dimensions (peak-to-valley height 0.1-10 μm, peak spacing 10-100 μm). This creates a friction coefficient that provides both smoothness for ease of writing and sufficient resistance to generate vibration feedback
Solution Approach 2:
The invention utilizes mechanical vibration by designing the surface roughness structure to interact with the ballpoint pen tip during writing. The controlled peaks and valleys create periodic friction variations that generate vibration sensations similar to authentic paper writing
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 sheet effectively reproduces the writing feel and vibration experienced when using a ballpoint pen, enhancing the tactile feedback on touch panels by adjusting the frictional force and standard deviation within specific ranges, thereby improving the overall writing experience.
Implementation Method 1
a difference between a maximum value and a minimum value of frictional force generated between the pen tip and the surface is 80 mN or more and 300 mN or less
Data Source
AI summary
A writing feel improving sheet comprising a base material and a writing feel improving layer with which a touch pen is brought into contact, wherein when a touch pen having a pen tip of 0.5 mm diameter is used to bring the pen tip into contact with a surface of the writing feel improving layer with which the touch pen is brought into contact and the touch pen is then linearly slid at a speed of 1.6 mm/second while applying a load of 200 g to the touch pen and maintaining an angle formed between the touch pen and the surface at 45°, a difference between a maximum value and a minimum value of frictional force generated between the pen tip and the surface is 80 mN or more and 300 mN or less, wherein the frictional force is measured between a point at which a sliding distance is 10 mm and a point at which the sliding distance is 100 mm. The writing feel improving sheet makes it possible to well reproduce the writing feel experienced when writing on paper with a ballpoint pen.