Emission-Area TFT Layout for High-Aperture OLED Pixels
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Solution Overview
Problem
Organic light emitting display devices face challenges in achieving a high aperture ratio, which affects their luminance and lifespan, due to the occupation of space by storage capacitors, leading to reduced adaptability for high-resolution displays.
Innovation Solution
The design includes a substrate with a pixel area having an emission area and a non-emission area, where the driving thin film transistor and capacitor are disposed in the emission area, allowing light to pass through, and the pixel driving circuit, including a switching circuit, is placed in the non-emission area, optimizing the aperture ratio and simplifying the structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a storage capacitor is provided per pixel to maintain current during light emission, then the device can maintain stable operation, but the capacitor occupies area in the pixel, reducing the aperture ratio
Solution Approach 1:
The patent moves the storage capacitor from the planar pixel area to the side wall of the pixel electrode, utilizing the vertical dimension and side surface area. This three-dimensional placement allows the capacitor to maintain its function while not occupying additional area in the emission region, thereby resolving the contradiction between reliable operation and high aperture ratio.
2Illumination intensity
If the aperture ratio is increased to improve luminance and lifespan, then display performance is enhanced, but the storage capacitor requires sufficient area to maintain stable operation
Solution Approach 1:
By positioning the storage capacitor on the side wall of the pixel electrode rather than in the planar pixel area, the invention enables maximum aperture ratio for high luminance while maintaining adequate capacitor area for stable operation. The vertical side surface provides sufficient area for capacitor formation without compromising the emission area.
3Area of moving object
If the storage capacitor area is reduced to increase aperture ratio, then high resolution adaptability is improved, but the capacitor uniformity may be affected
Solution Approach 1:
The invention creates a localized capacitor region on the side wall of the pixel electrode with controlled dimensions. This localized placement on the vertical surface provides consistent geometric parameters for all capacitors in the display, ensuring uniformity in capacitance values while maintaining high aperture ratios across the entire display area.
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 enhances the aperture ratio, improves display performance by increasing luminance, and extends the lifespan of the light emitting diode while ensuring uniformity of the capacitor, resulting in better picture quality.
Implementation Method 1
an organic light emitting diode which injects holes from an anode and electrons from a cathode into a light emitting layer and emits light when an exciton generated by combination of the injected holes and electrons changes its state from an excited state to a ground state
Data Source
AI summary
A light emitting display device includes a substrate, a pixel area having an emission area and a non-emission area on the substrate, a light emitting diode disposed in the pixel area, and a pixel driving circuit electrically connected with the light emitting diode and having a driving thin film transistor disposed in the emission area, wherein light emitted from the light emitting diode can be emitted to the outside of the substrate by passing through the substrate.