OLED Pixel Circuit for 256-Grayscale Display via Segmented Driving
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Solution Overview
Problem
Existing pixel circuits for OLED displays are unable to achieve 256 grayscale display without significantly increasing costs, limiting their ability to provide a sufficient number of grayscales.
Innovation Solution
A pixel circuit design incorporating a light emitting element, multiple driving circuits, control circuits, and energy storage circuits, which allows for the generation of driving currents and control of voltage settings to enable multi-grayscale display by connecting or disconnecting transistors under specific control signals, thereby driving the light emitting element to emit light at various intensities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional pixel circuits are used, then the device complexity is low, but the grayscale display capability is limited and cannot achieve 256 grayscales
Solution Approach 1:
The pixel circuit is divided into multiple independent driving circuits (first driving circuit, second driving circuit) and control circuits. Each driving circuit can be independently controlled to connect or disconnect, enabling different grayscale levels by combining their outputs. This segmentation allows the circuit to achieve 256 grayscales while maintaining manageable complexity through modular design.
Solution Approach 2:
The patent employs dynamic control of transistor connections through control circuits that can connect or disconnect the first and second driving circuits based on grayscale requirements. The dynamic switching capability allows the same circuit structure to adapt to different grayscale levels (from 1 to 256) without physical reconfiguration, resolving the contradiction between versatility and complexity.
2Adaptability or versatility
If more driving circuits are added to increase grayscale levels, then the grayscale display capability improves, but the device complexity increases significantly
Solution Approach 1:
The control circuits serve multiple functions: they control the connection/disconnection of driving circuits, manage voltage writing to nodes, and coordinate the operation of energy storage circuits. This multi-functionality reduces the need for separate dedicated circuits for each function, thereby increasing grayscale capability without proportionally increasing overall circuit complexity.
Solution Approach 2:
The patent implements a hierarchical control structure where control circuits nest within the pixel circuit architecture, managing multiple driving circuits and energy storage elements. The control circuits are further divided into sub-circuits (first control sub-circuit, second control sub-circuit) that work in a nested manner to achieve precise grayscale control, allowing high versatility with organized complexity.
3Manufacturing precision
If the pixel circuit uses multiple driving circuits and control circuits, then the grayscale display precision improves, but the manufacturing complexity increases
Solution Approach 1:
The patent achieves precise grayscale control by changing voltage parameters rather than requiring complex physical structures. The control circuits write specific voltages to nodes (first node, second node) which then control the driving circuits to produce different grayscale levels. This parameter-based control (voltage modulation) simplifies manufacturing compared to precision mechanical or structural variations, while maintaining high grayscale precision.
Data Source
AI summary
A pixel circuit includes a light emitting element, a first driving circuit, a second driving circuit, a first control circuit, a setting circuit, a first energy storage circuit, a second control circuit and a control data voltage writing-in circuit. The first control circuit controls to connect or disconnect the control end of the first driving circuit and the control end of the second driving circuit under the control of the potential of the first node. The second control circuit provides the second setting voltage to the control end of the first driving circuit, and connects or disconnects the control end of the first driving circuit and the connection node under the control of the control signal provided by the charging control end; the control data voltage writing-in circuit writes the control data voltage into the first node under the control of the first writing-in control signal.