Pixel Circuit Layout for Uniform OLED Initial Luminance
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Solution Overview
Problem
Display quality deterioration due to characteristic differences among pixels in light emitting display devices, leading to issues such as initial luminance differences and impaired variable refresh rate characteristics at low grayscales.
Innovation Solution
Designing pixel circuits with transistors of different operational modes (double-gate, first-gate, and second-gate) to address capacitance differences among pixels, thereby reducing response time variations and improving image quality by equalizing initial luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the number of light emitting diodes and pixel circuit portions is increased to improve display quality, then display quality is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges the gate electrode and source electrode into a single conductive pattern, eliminating the need for separate gate and source electrodes. This reduces the number of manufacturing steps and pattern alignment requirements, thereby reducing manufacturing complexity while maintaining display quality
Solution Approach 2:
The single conductive pattern serves multiple functions simultaneously as both the gate electrode and source electrode for the transistor, as well as functioning as a signal line. This multi-functionality reduces the overall number of components needed in the pixel circuit, simplifying the device structure
2Ease of manufacture
If the number of manufacturing steps is reduced to simplify production, then ease of manufacture is improved, but manufacturing precision deteriorates
Solution Approach 1:
By combining the gate electrode and source electrode into one conductive pattern, the patent reduces the number of photolithography steps and etching processes required. Fewer manufacturing steps mean fewer opportunities for alignment errors and process variations, thereby maintaining manufacturing precision while improving ease of manufacture
Solution Approach 2:
The conductive pattern is designed with specific geometric configurations that allow it to perform multiple functions. The pattern includes distinct regions that serve as gate electrodes and source electrodes, with insulating films strategically placed to enable proper transistor operation, achieving functional segmentation without requiring separate physical electrodes
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
Prevents image quality defects by minimizing initial luminance differences and enhancing color stability and refresh rate performance across varying grayscales.
Implementation Method 1
Each pixel includes a light emitting diode that emits light in response to application of an drive signal
Data Source
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AI summary
A light emitting display device includes: a first pixel which displays a first color, and includes a first light emitting diode and a first pixel circuit portion connected to the first light emitting diode; and a second pixel which displays a second color, and includes a second light emitting diode and a second pixel circuit portion connected to the second light emitting diode. The first pixel circuit portion includes an initialization transistor which transmits an initialization voltage to the first light emitting diode, and the initialization transistor of the first pixel circuit portion includes a first gate electrode and a second gate electrode which receive a gate-on voltage. The second pixel circuit portion includes an initialization transistor which transmits the initialization voltage to the second light emitting diode, and the initialization transistor of the second pixel circuit portion includes a first gate electrode which receives the gate-on voltage.