Electrophoretic Display Substrate Spacing for Thermal Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electrophoretic display devices with microcapsules face reliability issues due to separation between substrates and conductive materials during thermal tests, leading to potential long-term defects from thermal expansion and shrinkage.
Innovation Solution
The display device design includes a conductive material with a thickness that creates a larger distance between substrates at the vertically conducting portion than in the display area, allowing substrates to warp and exert inward pressure, preventing separation, and additional adhesive layers for enhanced bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the thickness of the conductive material is set to make the distance between substrates at the vertically conducting portion the same as in the display area, then color irregularity is prevented, but separation occurs between substrates and conductive material during thermal tests due to thermal expansion and shrinkage
Solution Approach 1:
The invention changes the thickness parameter of the conductive material specifically at the vertically conducting portion to be greater than in the display area. This parameter change creates a distance difference between substrates at the conducting portion versus the display area, allowing thermal expansion and shrinkage during temperature cycling without causing separation or defective continuity.
Solution Approach 2:
The conductive material is given different thicknesses at different locations: thicker at the vertically conducting portion and thinner in the display area. This local quality differentiation allows the conducting portion to accommodate thermal stresses while maintaining overall distance uniformity for display quality.
2Reliability
If the thickness of the conductive material is increased to prevent separation during thermal tests, then reliability is improved, but the distance between substrates becomes non-uniform causing color irregularity
Solution Approach 1:
The conductive material thickness is locally optimized: increased at the vertically conducting portion to prevent separation during thermal tests, while kept thinner in the display area to maintain uniform distance and prevent color irregularity. This localized differentiation resolves the contradiction between reliability and manufacturing precision.
Solution Approach 2:
The thickness parameter of the conductive material is changed specifically at the vertically conducting portion to be greater than in the display area. This selective parameter change allows the system to achieve both reliability (through increased thickness at conducting portions) and manufacturing precision (through controlled thickness in display areas).
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 ensures long-term reliability by maintaining conductive material continuity and preventing microcapsule separation during reliability tests, while also simplifying the production process.
Implementation Method 1
the thickness of the conductive material is set such that the distance between the first substrate and the second substrate at the vertically conducting portion is larger than the distance between the first substrate and the second substrate in the display area
Implementation Method 2
electrophoretic display devices, each of which includes an electrophoretic dispersion liquid containing a liquid-phase dispersion medium and electrophoretic particles and utilizes the phenomenon in that the distribution state of the electrophoretic particles changes in the presence of an applied electric field, thus changing the optical properties of the electrophoretic dispersion liquid
Data Source
AI summary
A display device includes a first substrate, a second substrate, and microcapsules sandwiched between the first substrate and the second substrate, the microcapsules constituting a display area, the microcapsules encapsulating a display material whose optical properties change in response to electrical stimulation. A conductive material for conducting between the substrates is provided between the first substrate and the second substrate to constitute a vertically conducting portion. The thickness of the conductive material is set such that the distance between the first substrate and the second substrate at the vertically conducting portion is larger than the distance between the first substrate and the second substrate in the display area.