Electroactive Film for Flexible Display Haptic Feedback
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Solution Overview
Problem
Existing haptic devices for flexible display devices face challenges in modulating vibration frequency and response speed, with materials like shape memory alloy and electroactive ceramics having limitations such as slow response speed, short lifespan, and breakability, and dielectric elastomers requiring high driving voltage, making them unsuitable for low-voltage applications like mobile displays.
Innovation Solution
A touch sensitive element comprising an electroactive film formed from a fluorine-based terpolymer and a polymer with a sulfonyl group, represented by Chemical Formula 1, which enhances modulus and vibration strength by improving permittivity and glass transition temperature, allowing for improved tactile feedback without compromising light transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If shape memory alloy or electroactive ceramics are used for haptic devices, then vibration strength is improved, but response speed becomes slow and lifespan becomes short
Solution Approach 1:
The patent changes the material parameters by selecting electroactive polymer materials with specific glass transition temperatures and permittivity values. The first electroactive polymer has a glass transition temperature of -50°C to 0°C and permittivity of 10-20, while the second has a glass transition temperature of 0°C to 50°C and permittivity of 5-10. This parameter optimization enables both high response speed and vibration strength.
Solution Approach 2:
The patent uses a composite structure with two different electroactive polymers having distinct glass transition temperatures and permittivity ranges. This composite material approach combines the advantages of both materials to achieve improved response speed and vibration strength simultaneously, while avoiding the limitations of single-material solutions.
2Illumination intensity
If dielectric elastomer is used for haptic devices, then light transmittance is improved, but driving voltage becomes high
Solution Approach 1:
The patent optimizes material parameters by selecting electroactive polymers with specific permittivity ranges (first polymer: 10-20, second polymer: 5-10) and glass transition temperatures. These parameter changes enable the material to achieve high light transmittance while reducing the driving voltage to 3.3V or lower, making it suitable for mobile display applications.
3Strength
If PVDF is used for haptic devices, then modulus is improved, but process safety becomes poor due to high voltage polling requirement
Solution Approach 1:
The patent changes the material parameters by selecting electroactive polymers with specific glass transition temperatures (-50°C to 50°C ranges) and permittivity values (5-20 ranges). These parameter optimizations enable the material to achieve high modulus while eliminating the need for high voltage polling processes, thereby improving process safety.
4Strength
If electroactive polymer with high permittivity is used, then vibration strength is improved, but glass transition temperature becomes high
Solution Approach 1:
The patent employs a composite material approach using two electroactive polymers with complementary properties. The first polymer has high permittivity (10-20) with a lower glass transition temperature (-50°C to 0°C), while the second polymer has moderate permittivity (5-10) with a higher glass transition temperature (0°C to 50°C). This composite structure balances vibration strength and glass transition temperature requirements.
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 solution provides a touch sensitive element with enhanced modulus and vibration strength, improving tactile perception in display devices while maintaining high light transmittance and reducing the driving voltage required, thus addressing the limitations of existing haptic technologies.
Implementation Method 1
an electroactive film which is formed of a fluorine based terpolymer and a polymer having a sulfonyl group
Data Source
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AI summary
The present disclosure relates to a touch sensitive element and a display device including the same. According to an exemplary embodiment of the present disclosure, the touch sensitive element includes an electroactive film which is formed of a fluorine based terpolymer and a polymer represented by Chemical Formula 1, wherein R is an ethyl group or a methyl group, and n is an integer of 1 or larger.