Double-Sided OLED Display with Selective Reflecting Layers
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Solution Overview
Problem
Existing double-sided organic EL display devices face challenges in manufacturing cost increases and light emitting characteristics due to the need for transmissive electrodes, and they struggle to display correct images without reversal for multiple viewers.
Innovation Solution
A display device configuration with a light emitting functional layer between two substrates, featuring a first and second pixel with respective electrodes and reflecting layers, allowing light emission from both sides while maintaining independent image formation on each side, and incorporating a transmissive region for external light passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If light emitting functional layers are formed on both sides of a cathode to create a double-sided display, then both front and back surfaces can be seen simultaneously, but manufacturing cost increases
Solution Approach 1:
The display device is divided into first pixel regions for front surface display and second pixel regions for back surface display. By segmenting the pixel regions and using a single light emitting functional layer with selective reflecting layer placement, the patent achieves double-sided display capability without duplicating the entire light emitting structure, thereby controlling manufacturing costs.
Solution Approach 2:
Reflecting layers are selectively formed only in the second pixel regions (back surface display areas) rather than uniformly across the entire device. This local application of reflecting layers allows light to be directed toward the back surface where needed, while maintaining cost-effectiveness by avoiding unnecessary materials and processes in the first pixel regions.
2Adaptability or versatility
If both anode and cathode are formed of transmissive members to enable double-sided display, then light can pass through both sides, but the width of selection of electrode materials is narrowed impacting light emitting characteristics
Solution Approach 1:
Instead of making both electrodes transmissive, the patent inverts the approach by using a non-transmissive cathode with selective reflecting layers. The reflecting layers serve as the transmissive solution by reflecting light in specific directions, thereby maintaining full electrode material selection freedom while achieving the required light transmission for double-sided display.
Solution Approach 2:
Reflecting layers act as intermediary elements between the light emitting functional layer and the back surface. These reflecting layers mediate the light path by reflecting light toward the back surface, enabling light transmission without requiring the cathode or electrodes to be transmissive, thus preserving electrode material selection flexibility.
3Adaptability or versatility
If a transmissive region is provided for face-to-face viewing, then multiple people can see each other and the display simultaneously, but light from the light emitting functional layer may interfere with display quality in that region
Solution Approach 1:
The transmissive region is created by locally removing reflecting layers from specific areas where face-to-face viewing is desired. This selective removal allows light to pass through for communication purposes while maintaining reflecting layers in display regions to ensure high display quality. The local modification approach balances both requirements without compromising overall display performance.
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 enables cost-effective, high-quality double-sided display with correct image orientation for multiple viewers, allowing simultaneous visibility of images and faces without reversing text or images, while minimizing manufacturing process additions.
Implementation Method 1
Organic EL (electroluminescent) devices, which use an electroluminescence phenomenon where light is emitted due to applying of an electric current
Implementation Method 2
a first reflecting layer disposed between the first pixel electrode and the first substrate
Data Source
AI summary
A display device includes a light emitting functional layer disposed between a first and second substrates; a first pixel which emits light to the second substrate and has a first pixel electrode disposed between the light emitting functional layer and the first substrate, a second electrode disposed between the light emitting functional layer and the second substrate, and a first reflecting layer disposed between the first pixel electrode and the first substrate; a second pixel which emits light to the first substrate side and has a second pixel electrode disposed between the light emitting functional layer and the first substrate, a second electrode disposed between the light emitting functional layer and the second substrate, and a second reflecting layer disposed between the second electrode and the second substrate; and a driving element which drives the first and second pixel electrodes is disposed above first substrate.