Pixel Circuit With Dual Switching Transistors For Display Quality
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Solution Overview
Problem
The display quality of light emitting devices can deteriorate due to variations in the characteristics of elements such as transistors and capacitive elements within the pixels.
Innovation Solution
A light emitting device with a pixel configuration that includes a current path with a light emitting element and a driving transistor, along with a capacitive element between the gate and source of the driving transistor. The pixel also includes two switching transistors connected to different power supply lines, allowing for independent control of current supply during write and light emission periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional pixel configuration with a single switching transistor is used, then the device complexity is low, but the display quality deteriorates due to element characteristic variations
Solution Approach 1:
The single switching transistor function is segmented into two separate switching transistors: a first switching transistor connected to a first power supply line and a second switching transistor connected to a second power supply line. This segmentation allows independent control of current supply paths, enabling compensation for element characteristic variations and improving display quality while maintaining reasonable device complexity
Solution Approach 2:
The invention introduces two power supply lines with different potentials (first power supply line and second power supply line) to provide variable voltage conditions. By changing the power supply parameters dynamically, the system can compensate for variations in transistor and capacitive element characteristics, thereby maintaining consistent display quality across different pixels and operating conditions
2Adaptability or versatility
If element characteristics are allowed to vary, then the device operation is flexible, but the display quality deteriorates
Solution Approach 1:
The dual switching transistor configuration with separate power supply lines creates a feedback mechanism where the system can respond to element characteristic variations. By independently controlling the first and second switching transistors, the system can adjust current distribution to compensate for variations in transistor threshold voltages and capacitive element values, maintaining display quality while allowing operational flexibility
Data Source
AI summary
A light emitting device including a pixel that includes a current path including a light emitting element and a driving transistor is provided. The pixel further includes a first switching transistor arranged between the path and a first power line, a second switching transistor arranged between the path and a second power line, and a write transistor to write a luminance signal in the gate. A potential of the first power line is lower than that of the second power line. One frame period includes a write period in which the write transistor is rendered conductive to write the luminance signal, and a light emission period. In the write period, the second switching transistor is rendered conductive while the write transistor is rendered conductive, and in the light emission period, the first switching transistor is rendered conductive.