Pixel Driving Transistor Layout for Low-Leakage Black Display
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Solution Overview
Problem
Display devices face challenges in achieving high contrast due to leakage currents from driving transistors when in a non-light-emitting state, which affects black display quality.
Innovation Solution
The implementation of a display device with a pixel array configuration that includes a light emitting element, a driving transistor with diffusion regions of a first conductivity type, and a gate electrode of a second conductivity type opposite to the first, which suppresses leakage current by increasing the threshold voltage and using a light emission control transistor to manage the current path effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional driving transistor is used to supply current to the light emitting element, then the display device can operate, but leakage current occurs when the transistor is turned off, degrading black display quality
Solution Approach 1:
The patent changes the conductivity type parameter of the gate electrode to be opposite to the diffusion regions (e.g., N-type gate for P-type diffusion regions), which fundamentally alters the transistor's electrical characteristics to achieve higher threshold voltage and reduced leakage current
Solution Approach 2:
The patent applies different conductivity types to different parts of the transistor structure - the diffusion regions have one conductivity type while the gate electrode has the opposite conductivity type, creating localized electrical properties that suppress leakage while maintaining switching function
2Object-generated harmful factors
If the threshold voltage of the driving transistor is increased to suppress leakage current, then black display quality improves, but the transistor's on-state current capability may be reduced
Solution Approach 1:
The patent changes the conductivity type parameter of the gate electrode to be opposite to the diffusion regions, which simultaneously achieves higher threshold voltage for leakage suppression while maintaining adequate on-state current through proper doping concentration control
Data Source
AI summary
A display device in which a plurality of pixels are arranged in an array is provided. Each of the plurality of pixels comprises a current path that includes a light emitting element and a first transistor, and a second transistor for transmitting a luminance signal. The first transistor comprises diffusion regions arranged in the current path, and a gate electrode to which the luminance signal is transmitted from the second transistor. The diffusion regions are of a first conductivity type, and the gate electrode is of a second conductivity type opposite to the first conductivity type.