OLED Pixel Circuit Parallel Transistors Gray Scale Brightness
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Solution Overview
Problem
Current OLED display products suffer from suboptimal display performance, particularly in terms of brightness uniformity across different gray scales.
Innovation Solution
A pixel circuit is designed with a drive module comprising two transistors connected in parallel, where the first transistor has a larger subthreshold swing than the second transistor. This configuration allows for adjusted drive currents based on gray scale values, enhancing brightness uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional single-transistor drive module is used, then the device complexity is low, but the brightness uniformity across different gray scales deteriorates
Solution Approach 1:
The drive module is segmented into two parallel transistors (first transistor and second transistor) with different subthreshold swings, allowing independent optimization for different gray scale ranges. This segmentation enables each transistor to handle specific gray scale intervals, improving overall brightness uniformity while managing device complexity through functional division.
Solution Approach 2:
Different transistors are assigned different local qualities in terms of subthreshold swing characteristics. The first transistor has a first subthreshold swing optimized for certain gray scales, while the second transistor has a second subthreshold swing optimized for other gray scales. This local quality differentiation resolves the contradiction by tailoring transistor properties to specific operational requirements.
2Manufacturing precision
If transistors with identical subthreshold swings are used, then the device complexity is low, but the display performance at different gray scales deteriorates
Solution Approach 1:
The patent introduces asymmetry by using two transistors with deliberately different subthreshold swing values in the drive module. This asymmetric configuration allows the circuit to handle different gray scale ranges more effectively, improving display performance across the full gray scale spectrum while accepting the increased transistor configuration complexity.
Solution Approach 2:
The subthreshold swing parameter is intentionally changed between the two transistors to optimize performance for different gray scale intervals. By varying this critical parameter, the patent achieves better overall display performance while the transistor configuration complexity increases to accommodate the parameter differentiation.
3Manufacturing precision
If a single transistor provides drive current for all gray scales, then the device complexity is low, but the brightness uniformity at low gray scales deteriorates
Solution Approach 1:
The gray scale range is segmented into different intervals handled by different transistors. The first transistor with its specific subthreshold swing is assigned to handle particular gray scale intervals, improving brightness uniformity at low gray scales while the drive module composition becomes more complex to accommodate this segmentation.
4Manufacturing precision
If high subthreshold swing transistors are used, then the brightness uniformity at low gray scales is improved, but the brightness effect at high gray scales deteriorates
Solution Approach 1:
Different transistors are assigned different local qualities in terms of subthreshold swing characteristics. The first transistor has a first subthreshold swing optimized for certain gray scales, while the second transistor has a second subthreshold swing optimized for other gray scales. This local quality differentiation resolves the contradiction by tailoring transistor properties to specific operational requirements.
Solution Approach 2:
The gray scale range is segmented into different intervals handled by different transistors. The first transistor with its specific subthreshold swing is assigned to handle particular gray scale intervals, improving brightness uniformity at low gray scales while the drive module composition becomes more complex to accommodate this segmentation.
Data Source
AI summary
The present application discloses a pixel circuit and a method for driving the same, a display panel, and a display apparatus. The pixel circuit includes a drive module, where the drive module includes a first transistor and a second transistor connected in parallel, a first terminal of the first transistor and a first terminal of the second transistor are connected to form a first end of the drive module, a second terminal of the first transistor and a second terminal of the second transistor are connected to each other as a second end of the drive module, a first gate of the first transistor and a second gate of the second transistor are connected to each other to form a control end of the drive module, and a subthreshold swing of the first transistor is greater than a subthreshold swing of the second transistor.