Emission Driver Layout for Dead-Space and Power-On Flash Control
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Solution Overview
Problem
Display devices face issues with increased dead space due to the complexity of emission drivers and a flashing phenomenon during power-on, which affects image display efficiency.
Innovation Solution
The design includes a simplified configuration for the emission driver with stages of transistors connected to emission lines, a common resistor, and a flexible circuit board to reduce dead space and prevent flashing by managing power source voltages and signal levels during different frame periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a scan driver and an emission driver are mounted on a display substrate, then the display device can control pixel emission, but the dead space in which an image cannot be displayed increases
Solution Approach 1:
The emission driver is divided into multiple stages, with each stage controlling a specific emission line. This segmentation allows for more compact arrangement and reduces the overall area occupied by the emission driver, thereby reducing dead space while maintaining pixel emission control functionality
Solution Approach 2:
The emission driver stages are arranged in a distributed manner across the display substrate, utilizing two-dimensional space more efficiently. By spreading out the driver components rather than concentrating them in one location, the design reduces the dead space impact while maintaining full emission control capability
2Reliability
If a conventional emission driver configuration is used, then complete emission control is achieved, but the device complexity increases
Solution Approach 1:
The emission driver is segmented into multiple independent stages, where each stage contains a minimal set of transistors required to control a specific emission line. This modular segmentation reduces the complexity of each individual stage while maintaining complete emission control through coordinated operation of all stages
Solution Approach 2:
Instead of using a centralized emission driver with high complexity, the patent inverts the approach by distributing emission control functions across multiple simple stages. Each stage is minimally complex, but the collective system achieves complete emission control through the coordinated action of all stages
3Reliability
If power is applied during the first frame period, then the display device can operate, but a flashing phenomenon occurs
Solution Approach 1:
During the first frame period, the emission driver stages are configured to maintain emission signals at a turn-off level before actual display operation begins. This preliminary action ensures that pixels remain non-emissive during power-on, preventing the flashing phenomenon while preparing the system for normal operation in subsequent frame periods
Solution Approach 2:
The patent implements different operational modes for different frame periods: the first frame period uses a special power-on mode with emission signals held at turn-off level to prevent flashing, while subsequent frame periods use normal emission control. This periodic differentiation between frame periods eliminates the harmful flashing effect during initial power application
Data Source
AI summary
A display device of the invention includes pixels each connected to at least one of scan lines and at least one of emission lines, a scan driver providing scan signals to the scan lines, and an emission driver including stages connected to the emission lines, each of the stages providing an emission signal to a corresponding emission line. A first stage among the stages includes a first transistor including a first electrode connected to a first power source line, a second electrode connected to a first emission line, and a gate electrode connected to a first scan line, and a second transistor including a first electrode connected to a first node and a second electrode connected to the first emission line.