Opposite Phase Enable and Gate Signals in OLED Pixel Circuits
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Solution Overview
Problem
OLED display apparatuses face challenges in compensating threshold voltage, carrier mobility, reducing afterimages, and alleviating device aging, which are not effectively addressed by current pixel circuit technologies.
Innovation Solution
A pixel circuit comprising a data writing sub-circuit, a light-emitting control sub-circuit, and a driving sub-circuit, with specific transistor configurations and reset sub-circuits, that compensates data voltage signals and provides driving current to light-emitting devices, while also incorporating a gate driver circuit with cascade shift registers to manage enable and gate signals for efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pixel circuits are used in OLED displays, then the basic display function is achieved, but threshold voltage compensation, carrier mobility compensation, afterimage reduction, and aging alleviation are not effectively addressed
Solution Approach 1:
The pixel circuit is divided into multiple functional sub-circuits: a data writing sub-circuit for writing and compensating data voltage signals, a light-emitting control sub-circuit for controlling the light-emitting device, and a driving sub-circuit for providing driving current. This segmentation allows each sub-circuit to specialize in specific compensation functions (threshold voltage, carrier mobility) while maintaining overall circuit manageability and reducing the complexity of implementing multiple compensation mechanisms in a single circuit block.
2Manufacturing precision
If multiple compensation functions are added to the pixel circuit, then threshold voltage and carrier mobility compensation are improved, but the circuit complexity and number of components increase
Solution Approach 1:
The data writing sub-circuit is designed to perform multiple functions: writing data voltage signals, compensating threshold voltage through dual gate signals, and compensating carrier mobility through coordinated enable and gate signals. The light-emitting control sub-circuit similarly handles both threshold voltage compensation and light-emitting control. This multi-functionality allows a single sub-circuit to provide multiple compensation mechanisms, improving manufacturing precision without proportionally increasing overall circuit complexity.
Solution Approach 2:
The patent combines threshold voltage compensation and carrier mobility compensation functions within integrated sub-circuits rather than implementing them as separate independent circuits. The data writing sub-circuit merges data writing, threshold voltage compensation, and carrier mobility compensation operations, while the light-emitting control sub-circuit merges threshold voltage compensation and light-emitting device control. This merging reduces the total number of separate components and interconnections required.
3Productivity
If dual-phase enable signals and gate signals are used, then data writing and light-emitting control are improved, but signal synchronization and timing complexity increase
Solution Approach 1:
The patent employs periodic dual-phase enable signals (first enable signal and second enable signal with opposite phases) and dual-phase gate signals (first gate signal and second gate signal with opposite phases) to control the pixel circuit operations. The data writing sub-circuit uses the first gate signal and second gate signal to write and compensate data voltage signals during specific phases, while the light-emitting control sub-circuit uses the first enable signal and second enable signal to control light-emitting during different phases. This periodic dual-phase action improves productivity by enabling simultaneous data writing and light-emitting control operations without interference, while the systematic phase opposition simplifies timing coordination compared to arbitrary multi-signal schemes.
Data Source
AI summary
A pixel circuit includes a data writing sub-circuit, a light-emitting control sub-circuit and a driving sub-circuit. The data writing sub-circuit is connected to the driving sub-circuit, and is configured to write a data voltage signal into the driving sub-circuit and compensate it, in response to a first gate signal and a second gate signal. The light-emitting control sub-circuit is connected to the driving sub-circuit, and is configured to close a line between a first power supply voltage terminal and a second power supply voltage terminal, in response to a first enable signal and a second enable signal. The driving sub-circuit is configured to provide a driving current to a light-emitting device through the closed line according to the written data voltage signal. Phases of the first enable signal and the first gate signal are opposite, and phases of the second enable signal and the second gate signal are opposite.