Display Device Pixel Electrode Overlap for Color Synchronization
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Solution Overview
Problem
Display devices face challenges in preventing the color spreading phenomenon due to differences in emission times and hysteresis characteristics of thin film transistors, leading to brightness deviations and color blurring, especially when transitioning between black and white frames.
Innovation Solution
The implementation of a display device structure that includes capacitors with varying capacities for each color pixel, allowing for differential on-bias voltage application to synchronize the emission times of red, green, and blue pixels, thereby stabilizing the voltage and reducing light emission delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thin film transistors are used in display devices, then the display device can operate with TFTs, capacitors, and wirings, but color spreading phenomenon occurs due to hysteresis characteristics and emission time differences
Solution Approach 1:
The patent applies different overlapping areas between electrode layers and source regions for different color pixels (red, green, blue). Specifically, the green pixel has a larger overlapping area than the red and blue pixels, which have equal overlapping areas. This local differentiation compensates for the different emission characteristics of each color pixel, synchronizing their emission times and preventing color spreading phenomenon.
Solution Approach 2:
The patent changes the physical parameter of overlapping area to adjust the on-bias voltage applied to different color pixels. By varying the overlapping area between the electrode layer and source region, the capacitance changes, which directly controls the amount of on-bias voltage applied. This parameter adjustment synchronizes the emission times of different color pixels, eliminating color spreading.
2Ease of manufacture
If uniform electrode layer structure is used across all pixels, then manufacturing is simplified, but brightness deviations occur due to hysteresis characteristics
Solution Approach 1:
The patent implements local quality by making the overlapping area between the electrode layer and source region different for different color pixels. The green pixel electrode layer has a larger overlapping area while red and blue pixels have equal, smaller overlapping areas. This localized structural differentiation compensates for hysteresis characteristics and ensures uniform brightness across all pixels.
3Reliability
If different overlapping areas are used for different color pixels, then color spreading is prevented, but device complexity increases
Solution Approach 1:
The patent resolves the complexity issue by implementing local quality only where needed - specifically in the overlapping area between electrode layers and source regions. The overall device structure remains simple, with only the electrode layer dimensions being differentiated by color pixel type. This targeted approach achieves color synchronization without requiring complex restructuring of the entire device.
Solution Approach 2:
The patent simplifies the solution by changing only one key parameter - the overlapping area between electrode layer and source region - while keeping all other device parameters uniform. This single parameter change is sufficient to synchronize emission times and prevent color spreading, avoiding the need for multiple complex modifications.
Data Source
AI summary
A display device includes: a first driving transistor including a first gate electrode and a first semiconductor layer including a first source region and a first drain region, the first driving transistor being in a first pixel area of a substrate; a second driving transistor including a second gate electrode and a second semiconductor layer including a second source region and a second drain region, the second driving transistor being in a second pixel area adjacent the first pixel area of the substrate; a first electrode layer overlapping at least a portion of the first source region of the first driving transistor; a second electrode layer overlapping at least a portion of the second source region of the second driving transistor; a first power line electrically connected to the first electrode layer; and a second power line electrically connected to the second electrode layer.