Organic EL Display Substrate Thickness Optimization
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Solution Overview
Problem
The existing organic EL devices without color filters suffer from deteriorated display quality due to light reflection between the counter substrate and the reflection layer, leading to unwanted display patterns and reduced brightness.
Innovation Solution
A display device configuration where the transparent substrate's thickness is optimized to ensure that emitted light is reflected towards the non-display area, using a refractive index range of 1.2 to 1.6 and incorporating light-absorbing films or resins to prevent unnecessary light from entering the display area, thereby enhancing display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If color filters are omitted from the organic EL device, then brightness is increased, but display quality deteriorates due to light reflection between counter substrate and reflection layer
Solution Approach 1:
The patent converts the harmful light reflection between the counter substrate and reflection layer into a beneficial effect by optimizing the counter substrate thickness to direct reflected light toward the non-display area. The thickness is specifically designed so that light reflecting off the reflection layer and hitting the counter substrate is directed away from the display area, transforming what was previously a display quality issue into a feature that enhances display performance.
Solution Approach 2:
The patent applies parameter changes by optimizing the counter substrate thickness to a specific range (0.1mm to 0.5mm) and selecting materials with appropriate refractive indices (1.2 to 1.6). These parameter optimizations control the reflection angle and light path, ensuring that reflected light is directed toward the non-display area rather than the display area, thereby resolving the display quality deterioration while maintaining high brightness.
2Object-affected harmful factors
If transparent substrate thickness is increased to control light reflection, then display quality improves, but device size increases
Solution Approach 1:
The patent optimizes the counter substrate thickness to a specific range (0.1mm to 0.5mm) that achieves effective light reflection control while maintaining a thin overall device profile. This parameter optimization allows the substrate to be thick enough to control light paths and direct reflected light away from the display area, yet thin enough to avoid increasing device size significantly.
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 suppresses unwanted displays and maintains high-quality imaging by directing reflected light away from the display area, improving color purity and brightness.
Implementation Method 1
a refraction index of the transparent substrate is n1, a refractive index of a medium which comes into contact with the second surface is n2... Expression (1) described below is realized. n1 sin θ1=n2 sin θ2
Implementation Method 2
incorporating light-absorbing films or resins to prevent unnecessary light from entering the display area
Implementation Method 3
Light (red color light, green color light, and blue color light), the color purity of which is increased by the multi-reflection interference of reflected light
Implementation Method 4
the color purity of which is increased by the multi-reflection interference of reflected light
Data Source
AI summary
There is provided a display device including an element substrate that has a display area; and a counter substrate. When it is assumed that the length of the shortest edge of the display area is X1, the length of a longest diagonal line of the display area is X3, the thickness of the counter substrate is L1, the refraction index of the counter substrate is n1, the refractive index of the air is n2, and the minimum value of an angle, which is generated between a progress direction of light emitted from the organic EL elements and a normal vector direction is totally reflected in the surface, is α, the relationship of X1/(2 tan α)≤L1≤X3/(tan α) is realized.