Reflective Pattern in Double-Side Emission OLED Pixels
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Solution Overview
Problem
Existing organic light emitting display devices face challenges in achieving balanced light emission efficiency and reducing light leakage between pixels, particularly in double-side emission configurations.
Innovation Solution
A light emitting display device design incorporating a substrate with alternating top and bottom emission pixels, featuring a reflective pattern that redirects unwanted light emissions towards the desired emission surfaces, and a planarization layer to optimize light emission efficiency and prevent leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a double-side emission type display is implemented to improve luminance, then luminance is improved, but light leakage between pixels occurs
Solution Approach 1:
The patent applies this principle by using the pixel defining layer and reflective pattern to convert light that would otherwise leak between pixels into beneficial reflected light that enhances forward emission. The reflective pattern specifically redirects stray light back toward the emission direction, transforming the harmful light leakage into useful luminance enhancement for both top and bottom emission surfaces.
Solution Approach 2:
The pixel defining layer acts as an intermediary structure between adjacent pixels, physically blocking and redirecting light paths. The reflective pattern serves as an optical intermediary that mediates between stray light and the emission surfaces, redirecting light that would leak between pixels back toward the intended emission directions.
2Illumination intensity
If the second electrode thickness is increased in the second area to improve bottom emission, then bottom emission performance is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by varying the thickness of the second electrode across different regions of the display. Specifically, the second electrode has a greater thickness in the second area (bottom emission region) compared to the first area (top emission region), optimizing light emission characteristics for each specific emission direction without uniformly increasing complexity across the entire device.
Solution Approach 2:
The second electrode is segmented into regions with different thicknesses - thicker in the second area for bottom emission and thinner in the first area for top emission. This segmentation allows independent optimization of each emission surface's performance while managing overall device complexity through localized structural variations.
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
The solution enhances light emission efficiency and reduces light leakage between pixels, enabling improved luminance and image quality in double-side emission displays.
Implementation Method 1
a reflective pattern in the reflective pattern opening and spaced apart from the second electrode in the first area
Data Source
AI summary
A light emitting display device includes a substrate, a first electrode, a pixel defining layer, a light emitting layer, a second electrode, and a reflective pattern. The substrate includes a plurality of pixels, each including a top emission pixel in a first area and a bottom emission pixel in a second area. The first electrode is in the first area and the second area. The pixel defining layer includes pixel openings to expose the first electrode and reflective pattern openings between adjacent pixels. The light emitting layer is on the first electrode, and the second electrode is on the light emitting layer. The reflective pattern is in the reflective pattern opening and spaced from the second electrode in the first area.