PMOS Shift Register Circuit for Flexible OLED Gate Driver Integration
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Solution Overview
Problem
The existing Gate Driver on Array (GOA) technology faces challenges in providing sufficient gate signals for flexible OLED displays due to the need for compensating threshold voltage and mobility of thin-film transistors, making it difficult to integrate gate circuits without external ICs.
Innovation Solution
A shift register circuit utilizing PMOS transistors is designed to connect with a pixel-compensating circuit, comprising specific transistors and capacitors to generate and invert control signals, and includes a pulse signal generator for creating pulse signals with phase shifts, reducing the number of transistors and enhancing production efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional GOA technology is used to integrate gate circuits on array substrate, then external IC can be eliminated, but it becomes difficult to provide sufficient gate signals for flexible OLED displays requiring threshold voltage compensation
Solution Approach 1:
The patent inverts the conventional approach by using a PMOS-based shift register module to generate gate signals in reverse sequence, enabling the last scanned gate line to receive signals first. This inversion allows the circuit to provide sufficient gate signals for threshold voltage compensation in flexible OLED displays while maintaining integration on the array substrate, resolving the contradiction between adaptability and device complexity
Solution Approach 2:
The patent changes the transistor type parameter from conventional NMOS to PMOS throughout the shift register circuit. This parameter change enables the circuit to achieve both high-level and low-level signal output capabilities with fewer transistors, allowing sufficient gate signal provision for compensation circuits while reducing integration complexity on the array substrate
2Reliability
If more gate signals are added for threshold voltage compensation and mobility compensation, then display performance improves, but the number of transistors increases making integration difficult
Solution Approach 1:
The PMOS-based shift register module serves multiple functions: it generates gate scan signals, provides threshold voltage compensation signals, and enables mobility compensation. By making the shift register module universal and multi-functional, the patent achieves improved display performance through comprehensive compensation while avoiding the need to add separate compensation circuits that would increase transistor quantity and integration difficulty
Solution Approach 2:
The inverted signal generation approach allows a single shift register module to serve multiple compensation functions. By generating signals in reverse sequence with appropriate timing, the same circuit structure provides both threshold voltage compensation and mobility compensation, achieving enhanced reliability without proportionally increasing device complexity
3Productivity
If conventional shift register modules are used, then gate signals can be generated, but the number of transistors per module is large reducing production efficiency
Solution Approach 1:
The patent changes the fundamental parameter of transistor type from NMOS to PMOS throughout the shift register module. This parameter change enables the circuit to achieve the same signal generation function with fewer transistors by utilizing the inherent characteristics of PMOS devices, thereby reducing the transistor count per module and improving production efficiency through simpler fabrication processes
Solution Approach 2:
The patent extracts and eliminates redundant transistor components from the conventional shift register module design. By using PMOS transistors with their specific electrical characteristics, the circuit achieves the required signal inversion and generation functions with a reduced transistor count, removing unnecessary components and simplifying the module structure for higher production efficiency
Data Source
AI summary
The present disclosure provides a shift register circuit, adapted for connecting with a pixel-compensating circuit corresponding to the GOA unit. The shift register circuit comprises: an input module connecting with a signal input terminal, the input module is adapted for generating an output control signal based on an input signal supplied by the signal input terminal; a shift register module connecting with the input module, the shift register module is adapted for inverting the output control signal, so as to output an emission control signal toward a pixel-compensating circuit corresponding to the GOA unit; and wherein the shift register module includes a first capacitor, a second capacitor, a first transistor, a second transistor, a third transistor and a fourth transistor. The required amount of thin-film transistors (TFT) is small and entire PMOS design could save process and raise the production efficiency. The present application further provides a shift register unit.