Double-Sided EL Display With Independent Light-Shielding Layers
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Solution Overview
Problem
Conventional double-sided electroluminescent (EL) display devices face issues with image reversal on both sides of the panel, reduced light extraction efficiency due to matrix-type panel arrangement, and inability to adjust luminance balance and information density on both sides.
Innovation Solution
The EL display device features first and second pixel electrodes with a light-emitting functional layer sealed by a counter electrode and a sealing member, with light-shielding layers on the pixel electrodes and counter electrodes to enable independent light emission on both sides, improving light extraction efficiency and allowing for adjustable luminance and information density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a double-sided light-emitting structure is used, then light can be emitted from both front and rear sides, but the displayed image becomes reversed on front and rear sides making it impossible to display different images simultaneously
Solution Approach 1:
The light-emitting functional layer is divided into two independent light-emitting areas: a front-side light-emitting area and a rear-side light-emitting area. Each area has dedicated pixel electrodes and light-shielding layers that control light emission independently, allowing different images to be displayed on front and rear sides simultaneously without image reversal
Solution Approach 2:
Different regions of the light-emitting functional layer are given different functional characteristics. The front-side light-emitting area is optimized for front-side viewing with corresponding light-shielding layers, while the rear-side light-emitting area is optimized for rear-side viewing. This local differentiation enables independent image display on both sides
2Device complexity
If a matrix-type panel arrangement is used, then the panel structure is simplified, but the light extraction efficiency is reduced
Solution Approach 1:
Light-shielding layers are selectively placed in specific regions (non-light-emitting regions) while leaving light-emitting regions open. This local differentiation allows light to be extracted efficiently from the light-emitting areas without requiring complex light extraction structures across the entire panel, thus maintaining simple panel structure while improving light extraction efficiency
3Device complexity
If the same light-emitting area is used on both faces, then the panel structure is symmetric and simple, but the luminance balance between front and rear sides cannot be adjusted
Solution Approach 1:
The front-side light-emitting area and rear-side light-emitting area are designed with different characteristics to optimize luminance for each viewing side. Light-shielding layers are positioned differently for each area, and the pixel electrode arrangements are optimized independently, allowing luminance balance to be adjusted for front and rear sides while maintaining overall structural simplicity
Solution Approach 2:
The luminance characteristics of front and rear sides can be independently controlled through the light-shielding layer configurations and pixel electrode designs. This dynamic control capability allows the display to adapt to different viewing conditions and requirements on each side
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 allows for simultaneous display of different images on both sides of the panel without image reversal, enhances light-emitting efficiency, and facilitates adjustable luminance and information density, improving overall display performance.
Implementation Method 1
a light-emitting functional layer provided between the first and second pixel electrodes and the counter electrode
Data Source
AI summary
An EL display device has first and second pixel electrodes and a counter electrode formed of a transparent conductive film, a sealing-side light-emitting area for extracting light emitted from a light-emitting functional layer from a sealing member formed on the first pixel electrode, a substrate-side light-emitting area for extracting light emitted from the light-emitting functional layer from the substrate is formed on the second pixel electrode, a light-shielding layer which is adjacent to the first pixel electrode in the sealing-side light-emitting area and the counter electrode in the substrate-side light-emitting area is formed, and the light-emitting functional layer emits light independently in the sealing-side light-emitting area and the substrate-side light-emitting area.