Display Device Transistor Configuration for Current Deviation Reduction
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Solution Overview
Problem
In organic light emitting devices, the deviation of output current due to voltage differences between the input and output terminals of thin film transistors is significant in the linear region, affecting display characteristics.
Innovation Solution
The implementation of a display device with a specific configuration of transistors, including a scanning signal line, data line, switching transistor, driving transistor, and light-emitting element, where the first transistor operates in a saturation region and the driving transistor operates in a linear region, with controlled channel width to channel length ratios and connections to minimize current deviation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the driving transistor operates in the linear region to control current flow, then the device can regulate current to the light-emitting element, but the output current deviates significantly due to voltage differences between input and output terminals
Solution Approach 1:
The patent introduces a compensation transistor connected in parallel with the driving transistor as an intermediary element. This compensation transistor has its gate connected to the drain of the driving transistor, creating a feedback mechanism that compensates for voltage differences and threshold voltage variations, thereby stabilizing the output current while maintaining the driving transistor's current control capability in the linear region
Solution Approach 2:
The patent modifies the operating parameters by configuring the compensation transistor with specific width-to-length ratios relative to the driving transistor. By changing these geometric parameters and the resulting electrical characteristics, the system achieves current stabilization without altering the fundamental linear region operation of the driving transistor
2Ease of operation
If the transistor operates in the linear region for current regulation, then current control is achieved, but the output current is highly sensitive to voltage variations
Solution Approach 1:
The compensation transistor creates a feedback loop where the drain voltage of the driving transistor is fed back to the gate of the compensation transistor. This feedback mechanism automatically adjusts the compensation transistor's conductance to counteract voltage variations and threshold voltage deviations, reducing current sensitivity to parameter variations while maintaining regulation capability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration reduces the deviation of the driving current, enhancing display characteristics by stabilizing the output current and making it less sensitive to variations in transistor characteristics and voltage differences.
Implementation Method 1
The first transistor operates in a saturation region, and the driving transistor operates in a linear region
Data Source
AI summary
Embodiments of the present invention relate to a display device. In an embodiment, the display device includes a scanning signal line for transferring a scanning signal, a data line crossing the scanning signal line and transferring a data voltage, a switching transistor connected to the scanning signal line and the data line, a driving transistor connected to the switching transistor, a first transistor connected between the driving transistor and a driving voltage terminal, and a light-emitting element connected between the driving transistor and a common voltage terminal. The first transistor operates in a saturation region, and the driving transistor operates in a linear region. In this way, display characteristics may be improved by reducing deviation of a driving current due to deviation of characteristics of a driving transistor or a driving voltage.