Pixel Circuit Transistor Count Reduction for OLED Threshold Compensation
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Solution Overview
Problem
Traditional organic electroluminescence display devices require at least 6 transistors per pixel to compensate for threshold voltage variations, limiting the resolution due to the increased complexity of the pixel circuit.
Innovation Solution
A display device with a reduced number of transistors per pixel is achieved by using a circuit structure that includes 5 transistors and a storage capacitor, connected to various signal lines, allowing for efficient threshold compensation and improved resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If at least 6 transistors are used per pixel to compensate for threshold voltage variations, then the threshold compensation function is achieved, but the device complexity increases and resolution is limited
Solution Approach 1:
The patent merges the threshold compensation function with the pixel circuit by integrating a compensation transistor that shares control terminals with the driving transistor. This allows the compensation operation to be performed within the same pixel circuit using shared components, thereby reducing the total transistor count while maintaining compensation capability.
Solution Approach 2:
The compensation transistor is designed to serve multiple functions: it acts as both the compensation element for threshold voltage variation and as part of the pixel switching circuitry. By making the transistor universal, the patent eliminates the need for separate dedicated compensation transistors, thus reducing overall device complexity.
2Reliability
If at least 6 transistors are used per pixel for threshold compensation, then the display quality is maintained, but the area occupied by the pixel circuit increases
Solution Approach 1:
The patent combines multiple circuit functions into a smaller area by merging the compensation circuitry with the pixel circuit. The compensation transistor shares control terminals and spatial arrangement with other pixel transistors, reducing the total area required while maintaining display quality through effective threshold compensation.
3Reliability
If at least 6 transistors are used per pixel to compensate for threshold voltage, then the luminance uniformity is improved, but the manufacturing cost increases
Solution Approach 1:
The patent merges the compensation function into the pixel circuit, reducing the total transistor count from 6 to 5 per pixel. This reduction simplifies the manufacturing process by requiring fewer fabrication steps and materials, thereby lowering manufacturing costs while maintaining luminance uniformity through the integrated compensation mechanism.
Data Source
AI summary
A display device including pixel circuit groups containing pixel circuits. The pixel circuit groups each contain: a first transistor whose first terminal is connected to a power source potential line; and a sixth transistor whose control terminal is connected to a first scanning signal line and whose first terminal is connected to an image signal line. The pixel circuit each include: a second transistor whose control terminal is connected to a first node and whose first terminal is connected to a second terminal of the first transistor and a second terminal of the sixth transistor; a third transistor whose first terminal is connected to the first node and whose second terminal is connected to a second terminal of the second transistor; a fourth transistor whose first terminal is connected to the second terminal of the second transistor; and a fifth transistor whose first terminal is connected to the first node.