Pixel Circuit Capacitor Layout for Low-Frequency Display Flicker
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Solution Overview
Problem
Low-frequency driving methods for display devices result in increased leakage current and luminance differences between frames, causing flicker phenomena due to the power consumption issues in electronic devices like smartphones and laptops.
Innovation Solution
The display device incorporates a design with specific capacitor configurations, including a first and second capacitor, and a common capacitor electrode, which maintains constant voltage nodes, reducing leakage currents and improving low-frequency characteristics by optimizing the overlap areas and distances between active patterns and electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If low-frequency driving method is used to reduce power consumption, then battery consumption is reduced, but leakage current increases causing flicker phenomenon
Solution Approach 1:
The pixel circuit is divided into multiple transistor units (first transistor unit with first and second active patterns, third transistor unit with third and fourth active patterns) instead of using a single transistor. This segmentation allows independent control and compensation of leakage currents in different transistor units, enabling the circuit to maintain stable operation at low frequencies without flicker while still consuming less power.
Solution Approach 2:
Multiple capacitor elements (first capacitor, second capacitor, third capacitor, fourth capacitor) are combined within the pixel circuit to provide comprehensive voltage compensation. The capacitors work together to compensate for leakage currents across different transistor units, ensuring stable voltage levels during low-frequency driving periods, thereby preventing flicker while maintaining low power consumption.
2Use of energy by moving object
If low-frequency driving method is used, then power consumption is reduced, but luminance difference between frames occurs
Solution Approach 1:
The capacitor elements are pre-charged to appropriate voltage levels before the low-frequency driving period begins. During the extended frame period, these pre-charged capacitors actively compensate for leakage currents, maintaining stable voltage levels at critical nodes. This preliminary preparation ensures that luminance remains uniform across frames even when operating at low frequencies with reduced power consumption.
3Reliability
If multiple capacitor elements are added to compensate leakage current, then flicker is reduced, but device complexity increases
Solution Approach 1:
The multiple capacitor elements serve multiple functions simultaneously: they compensate for leakage currents in different transistor units, maintain voltage levels at various critical nodes, and work together to prevent flicker. By designing these capacitors to perform multiple compensation roles, the circuit achieves reliable flicker prevention without requiring separate dedicated compensation circuits for each transistor, thereby limiting the increase in overall device 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
This configuration effectively reduces leakage currents, maintains constant voltage, and prevents luminance decrease, thereby enhancing the low-frequency characteristics of the display device and eliminating flicker phenomena.
Implementation Method 1
the first electrode may constitute a first capacitor together with the first common conductive region and the second electrode may constitute a second capacitor together with the second common conductive region
Data Source
AI summary
A display device includes: a substrate, a first active pattern disposed on the substrate and including a first channel region, a second channel region spaced apart from each other, and a first common conductive region positioned between the first channel region and the second channel region, a second active pattern disposed on the substrate, spaced apart from the first active pattern, and including a third channel region, a fourth channel region spaced apart from each other, and a second common conductive region positioned between the third channel region and the fourth channel region, a first gate layer disposed on the first and second active patterns and including a first electrode overlapping the first active pattern, and a second gate layer disposed on the first gate layer and including a second electrode overlapping the second active pattern.