Organic EL Sub-Pixel Area Optimization for Current Density
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Solution Overview
Problem
Organic electroluminescence (EL) display devices face issues with unequal life spans of sub-pixels due to differing luminous efficiencies and electric current densities, leading to reduced overall device lifespan and increased power consumption, especially when displaying white, which requires higher current levels.
Innovation Solution
A display device with sub-pixels configured to have a larger light emission area for white than other colors, controlled by a control unit to manage electric current, allowing for optimized electric current distribution and extended lifespan by reducing the current density on the white sub-pixel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If equal area of light emission is provided for all sub-pixels, then manufacturing simplicity is maintained, but sub-pixels with poorer luminous efficiency experience shorter life span due to higher electric current density
Solution Approach 1:
The patent applies local quality by assigning different light emission areas to sub-pixels based on their specific luminous efficiency characteristics. Sub-pixels with poorer luminous efficiency are given larger light emission areas, while those with better efficiency have smaller areas. This localized differentiation allows each sub-pixel to operate at comparable current densities, equalizing their life spans while maintaining manufacturing feasibility through standardized fabrication processes.
2Illumination intensity
If larger electric current is applied to sub-pixels with poorer luminous efficiency to achieve predetermined luminance, then luminance requirement is met, but life span of those sub-pixels and the display device becomes shorter
Solution Approach 1:
The patent changes the physical parameter of light emission area to compensate for differences in luminous efficiency. By increasing the light emission area of sub-pixels with poorer efficiency, the patent reduces their current density while maintaining the same luminance output. This parameter change allows all sub-pixels to operate at optimized current levels, extending their life span while meeting luminance requirements.
3Illumination intensity
If white is displayed by emitting all three colors simultaneously, then white display is achieved, but power consumption increases due to higher current requirement
Solution Approach 1:
The patent implements dynamic control of sub-pixel operation by independently managing the activation and current levels of red, green, and blue sub-pixels. Instead of always emitting all three colors simultaneously, the system dynamically adjusts which sub-pixels are active based on the required luminance and color composition. This dynamic approach reduces power consumption by minimizing the number of simultaneously operating sub-pixels while maintaining white display capability.
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 extends the life span of the display device by smoothing the deterioration of all sub-pixels and reduces power consumption by optimizing the electric current usage, particularly for the white sub-pixel which consumes the most current.
Implementation Method 1
a self-luminous element configured to emit light by receiving supply of electric current
Data Source
AI summary
A display device includes a plurality of sub-pixels configured to display a plurality of colors including white. Each of the sub-pixels includes a self-luminous element configured to emit light by receiving supply of electric current, an input unit configured to input a luminance signal for determining luminance of the self-luminous element into the sub-pixel, and a control unit configured to control the supply of electric current to the self-luminous element. An area of light emission in each of the sub-pixels for the white is larger than an area of light emission in each of the sub-pixels for the other colors.