Pixel Circuit Storage Capacitor Layout for Uniform OLED Luminance
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Solution Overview
Problem
Existing electro-optical devices face challenges in miniaturizing pixel circuits while maintaining precise current supply to light-emitting elements, leading to luminance unevenness and display quality deterioration due to manufacturing errors and high driving ability requirements.
Innovation Solution
The device incorporates a configuration with scanning lines, data lines, potential lines, and pixel circuits, utilizing large-capacitance storage capacitors formed by adjacent data and potential lines to stabilize gate voltages, and includes additional storage capacitors and transistors to compensate for threshold variations and parasitic effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the pixel circuit is miniaturized to reduce display size and increase high definition, then the display resolution and size are improved, but the current supply precision to light-emitting elements deteriorates due to manufacturing errors in micro regions
Solution Approach 1:
The pixel circuit is divided into distinct functional regions: a first region containing the light-emitting element and associated capacitors, and a second region containing the transistor. This segmentation allows optimization of each region independently, maintaining current supply precision even when the overall pixel circuit is miniaturized.
Solution Approach 2:
The invention transitions from planar capacitor layouts to a three-dimensional stacked configuration where capacitors are positioned above and below the transistor gate. This vertical arrangement increases capacitance values without occupying additional lateral space, thereby maintaining electrical performance in miniaturized pixels.
2Speed
If the driving ability is increased to charge data lines in short time, then the charging speed is improved, but the precision of data signal output deteriorates
Solution Approach 1:
Storage capacitors are configured with sufficient capacitance values before the actual display operation to cushion against voltage fluctuations during rapid charging. This pre-configured capacitance acts as a buffer that maintains signal precision even when high-speed charging causes transient voltage variations.
3Measurement precision
If the pixel circuit is miniaturized, then the display size is reduced and definition is increased, but luminance unevenness is generated due to manufacturing errors
Solution Approach 1:
The invention changes the capacitance parameter by using stacked capacitor configurations with calculated capacitance values (e.g., first capacitor: 0.5-2.0 pF, second capacitor: 0.3-1.5 pF). These specific parameter ranges compensate for manufacturing variations in miniaturized circuits, maintaining luminance uniformity across the display.
4Manufacturing precision
If the current supply precision to light-emitting element is improved, then the luminance control is enhanced, but the device complexity increases due to additional capacitors and transistors
Solution Approach 1:
The transistor gate serves multiple functions: it controls the light-emitting element current and simultaneously acts as one electrode for both the first and second storage capacitors. This multi-functionality reduces the number of separate components needed, maintaining current precision without proportionally increasing circuit complexity.
Solution Approach 2:
The invention merges the transistor gate with the capacitor electrode structure, where the gate electrode serves as a common electrode for stacked capacitors. This consolidation reduces the total component count and interconnection complexity while maintaining the required electrical functions for precise current control.
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 enables precise current supply to light-emitting elements, reducing luminance unevenness and enhancing display quality by stabilizing gate voltages and compensating for manufacturing errors, thus achieving high-definition displays.
Implementation Method 1
a first storage capacitor of which one end is electrically connected to the gate of the driving transistor and which holds the voltage between the first gate and source of the driving transistor
Implementation Method 2
a light-emitting element emitting light at a luminance according to the current level
Data Source
AI summary
An electro-optical device is provided with a plurality of data lines, a plurality of potential lines supplied with a predetermined potential, a driving transistor controlling a current level according to the voltage between the gate and the source, a first storage capacitor which holds the voltage between the gate and a source of the driving transistor, and a light-emitting element. One data line among the plurality of data lines and one potential line among the plurality of potential lines are arranged to be adjacent to each other, and a second storage capacitor holding the potential of the one data line is formed by the one data line and the one potential line.