Pixel Driving Circuit With Auxiliary Transistor for Color Uniformity
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Solution Overview
Problem
OLED and LED display panels experience a color shift phenomenon due to brightness differences among sub-pixels with different colors under the same gray scale, leading to distorted display pictures.
Innovation Solution
A pixel driving circuit with an auxiliary transistor generating an auxiliary current to jointly drive the light emitting element with a driving current, adjusting the current magnitude to compensate for brightness differences among sub-pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional driving circuit with only a driving transistor is used, then the circuit structure is simple, but brightness differences occur among sub-pixels with different colors under the same gray scale
Solution Approach 1:
The patent segments the driving function into two independent transistors: a driving transistor for primary current control and an auxiliary transistor for brightness compensation. This segmentation allows each transistor to specialize in a specific function, with the auxiliary transistor specifically addressing brightness uniformity across different colored sub-pixels without complicating the overall circuit architecture.
Solution Approach 2:
The auxiliary transistor acts as an intermediary component that introduces a compensation current to counteract the inherent brightness differences among sub-pixels. This intermediary element mediates between the driving transistor's output and the light emitting element, adjusting the total current to achieve uniform brightness across red, green, and blue sub-pixels under the same gray scale.
2Ease of operation
If the same current is applied to light emitting elements with different colors, then the driving current is simple to control, but color shift phenomenon occurs due to different light emitting characteristics
Solution Approach 1:
The patent applies local quality by providing different current compensation to different colored sub-pixels through the auxiliary transistor. Each sub-pixel (red, green, blue) receives a tailored compensation current based on its specific light emitting characteristics, allowing precise color control while maintaining simple overall current management through the driving transistor.
Solution Approach 2:
The patent changes the current parameter dynamically by introducing an auxiliary current that compensates for the different light emitting efficiencies of various colored sub-pixels. This parameter adjustment occurs through the auxiliary transistor, which modifies the total current based on the specific color and gray scale requirements, thereby improving color accuracy without complicating the control mechanism.
3Illumination intensity
If an auxiliary transistor is added to generate auxiliary current, then brightness differences among sub-pixels are reduced, but the device complexity increases
Solution Approach 1:
The patent merges the driving function and compensation function into a unified pixel circuit architecture where the auxiliary transistor is integrated alongside the driving transistor. This merging allows both functions to operate cooperatively within a compact structure, achieving brightness uniformity without proportionally increasing overall circuit complexity.
Solution Approach 2:
The auxiliary transistor serves multiple functions: it compensates for brightness differences among sub-pixels, adjusts current based on gray scale requirements, and maintains color accuracy across different operating conditions. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity while achieving improved brightness uniformity.
Data Source
AI summary
The present disclosure provides a pixel driving circuit, a pixel driving method, and a display panel. The pixel driving circuit includes a light emitting element electrically connected between a first node and a second node; a driving transistor connected in series between the second node and the light emitting element; and an auxiliary transistor connected in series between a third node and the light emitting element, where the auxiliary transistor is configured to generate an auxiliary current to jointly drive the light emitting element with a driving current generated by the driving transistor.