OLED Scan Driver Logic Using Same-Conductivity Transistors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing scan drivers for organic light emitting display devices (OLEDs) with transistors of the same conductivity type as the pixels require complex circuits and fabrication processes, necessitating a simpler circuit design for efficient operation.
Innovation Solution
A scan driver circuit incorporating samplers, OR gates, and NAND gates with transistors of the same conductivity type, synchronized with clock and inverted clock signals to generate scan signals for pixel selection, allowing for a simpler and more efficient scan driver design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If transistors of the same conductivity type as the pixels are used in the scan driver, then the scan driver can be formed on the same substrate as the OLED, but the circuit becomes complicated and requires a complicated fabricating process
Solution Approach 1:
The scan driver circuit is divided into multiple functional blocks: a clock signal generation unit, a scan signal generation unit, and a data signal generation unit. Each unit is further segmented into specific functional components (e.g., ring oscillators for clock generation, samplers for signal sampling, OR/NAND gates for logic operations). This segmentation allows each module to be independently designed and optimized while maintaining compatibility with the same substrate technology as the OLED pixels.
Solution Approach 2:
The scan driver circuit is designed to perform multiple functions using the same transistor technology as the OLED pixels. The same conductivity type transistors are used throughout the scan driver, enabling it to generate clock signals, scan signals, and data signals while being compatible with the OLED substrate. This universal approach eliminates the need for separate fabrication processes for the scan driver and OLED.
2Ease of manufacture
If transistors of the same conductivity type are used in the scan driver, then fabrication on the same substrate is enabled, but satisfactory characteristics are not achieved
Solution Approach 1:
Different regions of the scan driver circuit are designed with specific local characteristics to achieve satisfactory performance. The clock signal generation unit uses ring oscillators with specific transistor sizing for stable clock generation. The sampler circuits use cross-coupled latch structures for reliable signal sampling. The logic gates (OR/NAND) are designed with optimized transistor dimensions for proper switching characteristics. Each local region is tailored to its specific functional requirements while using the same overall transistor technology.
Solution Approach 2:
The transistor parameters (width-to-length ratios, threshold voltages) are carefully adjusted in different circuit regions to achieve optimal performance. The ring oscillators use specific transistor dimensions for stable oscillation frequency. The sampler circuits use adjusted parameters for reliable latching. The logic gates have optimized parameters for fast switching and low power consumption. These parameter changes enable the scan driver to achieve satisfactory characteristics while using the same conductivity type transistors as the OLED pixels.
Data Source
AI summary
Provided is a scan driver that supplies a scan signal to an organic light emitting display device (OLED). The scan driver includes transistors of the same conductivity type. To generate individual scan signals, the scan driver includes samplers, each of which samples an input signal in synchronization with a clock signal or an inverted clock signal; and an OR gate and a NAND gate, each of which performs a logical operation on output signals of adjacent samplers and generates a scan signal. The samplers, the OR gate and the NOR gate include transistors of the same conductivity type.