Scan Driver Circuit for OLED Displays with Reduced Power and Area
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Solution Overview
Problem
Current display devices face challenges in achieving improved current drive capability, reduced circuit area, and lower power consumption, particularly in organic light-emitting display devices, where the existing scan driver architectures are inefficient and consume more power.
Innovation Solution
The proposed display device incorporates a scan driver with a novel architecture that includes multiple stages with node controllers, inverters, and buffers, utilizing transistors of different types to efficiently manage clock signals and output signals, reducing power consumption and circuit area while maintaining high current drive capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If existing scan driver architecture is used, then device complexity is maintained, but current drive capability is insufficient and power consumption is high
Solution Approach 1:
The scan driver is divided into multiple stages, with each stage independently driving a specific scan line. Each stage includes dedicated transistors (first transistor for clock signal, second transistor for output signal) that can be selectively activated. This segmentation allows the circuit to only activate the necessary transistors for current driving, reducing overall power consumption while maintaining sufficient current drive capability for each individual scan line.
Solution Approach 2:
The circuit dynamically switches between different transistor configurations based on operating conditions. The first transistor responds to clock signals while the second transistor responds to output signals, allowing the circuit to adapt its current driving path dynamically. This dynamic operation enables efficient current drive capability only when needed, reducing static power consumption and optimizing circuit area utilization.
2Use of energy by stationary object
If existing scan driver architecture is used, then circuit area is reduced, but power consumption increases
Solution Approach 1:
The scan driver operates in periodic cycles where clock signals and output signals are alternately applied to different transistors. During each period, only the required transistors are activated for current driving, while others remain inactive. This periodic activation pattern reduces average power consumption compared to continuously active circuits, while the compact staging arrangement keeps circuit area minimal.
Solution Approach 2:
Different regions of the circuit have specialized functions with optimized transistor configurations. The first transistor region handles clock signal processing while the second transistor region handles output signal processing. This local specialization allows each region to be optimized for its specific function, achieving low power consumption in each local area while maintaining overall compact circuit area through efficient spatial arrangement.
3Power
If more transistors are added to improve current drive, then current drive capability increases, but circuit area and power consumption increase
Solution Approach 1:
The circuit prepares current driving capability in advance by having dedicated first and second transistors ready in each stage. When a clock signal or output signal arrives, the corresponding transistor is already positioned and configured to immediately provide the required current drive. This preliminary preparation eliminates the need for additional transistors to be activated on-demand, achieving high current drive capability with minimal active components and reduced power consumption.
Solution Approach 2:
Each stage's transistors serve multiple functions: the first transistor handles both clock signal reception and current switching, while the second transistor handles output signal reception and current delivery to scan lines. This multi-functionality allows the circuit to achieve enhanced current drive capability using the same transistors for multiple purposes, avoiding the need for additional dedicated transistors that would increase power consumption and circuit area.
Data Source
AI summary
A display device includes: a plurality of pixels, each of which is connected to a corresponding one of a plurality of scan lines, and a scan driver including a plurality of stages, each of which supplies a scan signal to a corresponding one of the scan lines, each of the stages includes: a node controller which supplies a second output signal of a previous stage to a first node based on an input signal of a first clock terminal or a first output signal of the previous stage, a first inverter connected between the first node and a second node, a buffer which supplies a voltage of the second node to a first output terminal based on an input signal of a second clock terminal, and a second inverter connected between the first output terminal and a second output terminal.