Display Device Thermal Expansion Balance
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Solution Overview
Problem
Display devices face warping issues due to differences in thermal expansion coefficients between various materials used in their construction, which existing techniques struggle to fully address, particularly in optical sheets, organic EL devices, and semiconductor devices.
Innovation Solution
The implementation of a display device structure featuring a first resin substrate with a specific thermal expansion coefficient and a second resin substrate with a matching coefficient, both covered with insulation layers that have lower thermal expansion coefficients, to balance stresses and prevent warping, while ensuring high heat resistance and transparency where necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple materials with different thermal expansion coefficients are adhered together in optical sheets, then optical functionality is achieved, but warping occurs due to thermal expansion mismatch
Solution Approach 1:
The patent applies the thermal expansion principle by providing a warp prevention layer with a specific thermal expansion coefficient that is equal to or close to that of the optical functional member. This matching of thermal expansion coefficients between the warp prevention layer and the optical sheet prevents differential thermal expansion and contraction, thereby eliminating warping while maintaining optical functionality.
Solution Approach 2:
The patent employs composite materials by creating a multi-layer structure consisting of the optical sheet and a warp prevention layer. This composite structure combines materials with different properties: the optical sheet provides optical functionality while the warp prevention layer provides dimensional stability by having a matched thermal expansion coefficient, thus resolving the warping issue.
2Shape
If warp-reducing substrates are attached to organic EL devices, then warping is reduced, but device complexity increases
Solution Approach 1:
The patent uses the thermal expansion principle by forming the warp prevention layer from a material whose thermal expansion coefficient matches that of the optical functional member. This material selection strategy reduces warping without requiring complex structural modifications, thereby minimizing the increase in device complexity while achieving effective warp reduction.
3Shape
If warp prevention sheets are bonded to semiconductor chips, then warping is prevented, but manufacturing complexity increases
Solution Approach 1:
The patent applies the thermal expansion principle by selecting a warp prevention layer material with a thermal expansion coefficient equal to or close to that of the optical functional member. This approach prevents warping through material property matching rather than complex manufacturing processes, thereby maintaining ease of manufacture while achieving effective warp prevention.
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 reduces warping by balancing thermal expansion stresses between substrates, maintaining the device's shape stability across varying temperatures and preventing moisture ingress, thus enhancing the display device's reliability and performance.
Implementation Method 1
a first barrier layer which covers an inner surface of the first resin substrate and has a second thermal expansion coefficient which is lower than the first thermal expansion coefficient
Data Source
AI summary
According to one embodiment, a display device includes a first substrate including a first resin substrate having a first thermal expansion coefficient, and a first barrier layer having a second thermal expansion coefficient which is lower than the first thermal expansion coefficient, a second substrate including a second resin substrate having a third thermal expansion coefficient which is equal to the first thermal expansion coefficient, and a second barrier layer having a fourth thermal expansion coefficient which is lower than the third thermal expansion coefficient and is equal to the first thermal expansion coefficient, and a display element located between the first resin substrate and the second resin substrate.