Multi-Layer Adhesive for Haptic Display Vibration Control
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Solution Overview
Problem
Current haptic display devices face challenges in simultaneously achieving reliable haptic performance and minimizing vibration damping, while also maintaining visibility by reducing the difference in refractive indices of adhesive layers.
Innovation Solution
The implementation of a display device with multiple adhesive layers having different physical properties, where a first adhesive layer with a lower loss modulus and glass transition temperature is used in conjunction with a second adhesive layer having a higher loss modulus and glass transition temperature, optimized in thickness and composition to enhance vibration transmission and adhesiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single adhesive layer with high loss modulus and high glass transition temperature is used to ensure reliability and adhesiveness, then the bonding strength and thermal stability are improved, but the vibration damping increases and haptic performance deteriorates
Solution Approach 1:
The adhesive layer is divided into two distinct layers: a first adhesive layer with high loss modulus and high glass transition temperature for reliability, and a second adhesive layer with low loss modulus and low glass transition temperature for vibration transmission. This segmentation allows each layer to perform its specialized function without compromising the other.
Solution Approach 2:
Different regions of the adhesive structure are assigned different material properties: the first adhesive layer (closer to cover window) has high damping properties for reliability, while the second adhesive layer (closer to display panel) has low damping properties for vibration transmission. This local differentiation resolves the contradiction by optimizing each region for its specific function.
2Reliability
If adhesive layers with high adhesiveness are used to ensure reliability, then the bonding between layers is improved, but the vibration transmission to the center is damped
Solution Approach 1:
The adhesive system is segmented into two layers with different properties: the first adhesive layer provides high adhesiveness for reliable bonding, while the second adhesive layer provides low damping for efficient vibration transmission. This segmentation enables both functions to coexist without compromise.
3Productivity
If multiple adhesive layers with different physical properties are used to improve vibration transmission, then the haptic performance is improved, but the device complexity increases
Solution Approach 1:
The adhesive system is divided into two functional layers with distinct properties, enabling vibration transmission optimization without excessive complexity. The segmentation is minimal (only two layers) yet sufficient to achieve the desired performance improvement.
Solution Approach 2:
The invention changes key material parameters (loss modulus and glass transition temperature) of the adhesive layers to optimize vibration transmission. By adjusting these parameters in a controlled manner across two layers, the invention achieves performance improvement without unnecessary structural complexity.
4Productivity
If adhesive layers with optimized vibration transmission properties are used, then the haptic performance is improved, but the refractive index difference increases and visibility deteriorates
Solution Approach 1:
The invention optimizes specific material parameters (loss modulus and glass transition temperature) of the adhesive layers for vibration transmission while controlling other parameters (refractive index) to maintain visibility. This selective parameter optimization allows simultaneous improvement of haptic performance and maintenance of optical quality.
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
This configuration effectively transmits vibration to the center of the display device with minimal damping, improving haptic performance and reliability, while minimizing refractive index differences for enhanced visibility.
Implementation Method 1
the vibration generated in an actuator needs to be provided to the user without being damped
Implementation Method 2
a first adhesive layer which is disposed on the second adhesive layer and has a lower loss modulus or a lower glass transition temperature Tg than that of the second adhesive layer
Implementation Method 3
a first adhesive layer which is disposed on the second adhesive layer and has a lower loss modulus or a lower glass transition temperature Tg than that of the second adhesive layer
Data Source
AI summary
A display device includes a display panel, an adhesive layer on the display panel and comprising a plurality of layers having different loss modulus and glass transition temperatures Tg, a cover window on the adhesive layer, and an actuator at the cover window. Then, the adhesive layer includes a first adhesive layer having a lower loss modulus and a glass transition temperature Tg and a second adhesive layer having a higher loss modulus and a glass transition temperature Tg.