OLED Display Sub-Pixel Electrode Structure for Angle-Dependent Brightness
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Solution Overview
Problem
OLED display devices experience significant brightness reduction when viewed from different angles due to variations in sub-pixel electrode thicknesses, leading to inconsistent image quality across viewing angles.
Innovation Solution
Incorporating light-blocking patterns in the first sub-pixel and a double-layered structure in red, green, and blue sub-pixels, along with a single-layered structure in the white sub-pixel, to maintain consistent brightness and improve image quality by controlling light transmission and reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If different thicknesses of first electrodes are used in red, green, and blue sub-pixels to improve color purity and brightness, then color display quality is improved, but brightness becomes inconsistent across different viewing angles
Solution Approach 1:
The patent applies local quality by making the first electrode in the white sub-pixel have a different structure (single-layered with light-blocking pattern) compared to the red, green, and blue sub-pixels (double-layered without light-blocking pattern). This localized structural difference compensates for the brightness inconsistency caused by the micro cavity effect in colored sub-pixels, achieving uniform brightness across all sub-pixels at different viewing angles while maintaining color purity
2Illumination intensity
If a color filter layer is used in red, green, and blue sub-pixels to improve color purity, then color display quality is improved, but the device structure becomes more complex
Solution Approach 1:
The patent merges the color filtering function with the electrode structure by making the first electrode itself serve as the color filtering element through its double-layered structure in red, green, and blue sub-pixels. This integration eliminates the need for separate color filter layers, achieving color purity while reducing overall device structure complexity
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 ensures similar brightness across all sub-pixels regardless of viewing angles, enhancing overall image quality by stabilizing light emission and reducing angle-dependent brightness variations.
Implementation Method 1
an organic light emitting layer 55 emitting white light is formed on the first electrode 47 all over a display area
Implementation Method 2
red, green and blue color filter patterns 45a, 45b and 45c are formed under the first electrodes 47 in the second, third and fourth sub-pixels SP2, SP3 and SP4, respectively. the white light passes through the red, green and blue color filter patterns 45a, 45b and 45c in the second, third and fourth sub-pixels SP2, SP3 and SP4 to produce red, green and blue light
Implementation Method 3
the first electrodes 47 of the second, third and fourth sub-pixels SP2, SP3 and SP4 have different thicknesses to cause a micro cavity effect. by making a difference in thicknesses of the first electrodes 47 at the sub-pixels SP2, SP3 and SP4, the OLED display device 2 may have the improved brightness and color purity because of the micro cavity effect
Data Source
AI summary
An organic light emitting diode display device includes a first substrate including a display area, wherein a plurality of pixels each including sub-pixels is defined in the display area; a switching thin film transistor and a driving thin film transistor in each of the sub-pixels over the first substrate; light-blocking patterns in at least one of the sub-pixels; a color filter layer in at least one sub pixel; a first passivation layer over the switching thin film transistor, the driving thin film transistor and the light-blocking patterns; a first electrode in each of the sub-pixels over the first passivation layer; an organic light emitting layer on the first electrode all over the display area; and a second electrode on the organic light emitting layer all over the display area.