Dual-Gate Drive Transistor for High-Definition Display Pixel Circuits
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Solution Overview
Problem
The existing display devices with a series connection of transistors for light-emitting elements face challenges in achieving high definition due to increased transistor count and lower aperture ratios, especially in bottom-emitting structures.
Innovation Solution
A display device configuration with a drive transistor having a double gate structure, a write transistor, and a capacitor, where the drive transistor is controlled by a light emission control signal to manage the duty ratio of light emission periods, reducing the number of transistors in the pixel circuit and enabling high definition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a light emission control transistor is connected in series with the drive transistor to control duty ratio, then light emission control is achieved, but the number of transistors in the pixel circuit increases
Solution Approach 1:
The invention merges the drive transistor and light emission control transistor into a single integrated transistor structure. The drive transistor includes a first gate electrode connected to the gate line and a second gate electrode connected to the light emission control line, allowing both driving and light emission control functions to be performed by one transistor, thereby reducing the total number of transistors in the pixel circuit while maintaining full control functionality
Solution Approach 2:
The drive transistor is designed with dual gate electrodes that enable it to perform multiple functions: the first gate electrode controls the overall transistor operation for driving the light-emitting element, while the second gate electrode provides light emission control by adjusting the duty ratio. This multi-functional design eliminates the need for a separate control transistor
2Ease of operation
If multiple transistors are used in the pixel circuit for drive and control, then control functionality is improved, but the aperture ratio decreases
Solution Approach 1:
By combining the drive and light emission control functions into a single transistor with dual gate electrodes, the invention reduces the total transistor area occupied in the pixel circuit. This merging eliminates redundant transistor structures and interconnections, thereby increasing the aperture ratio while preserving complete control functionality
Solution Approach 2:
The invention adds a vertical dimension to the control architecture by stacking gate electrodes above and below the semiconductor layer. This three-dimensional transistor structure allows multiple control functions to be implemented within a compact footprint, reducing the horizontal area required and thus increasing the aperture ratio
3Area of stationary object
If the number of transistors is reduced in the pixel circuit, then aperture ratio improves, but control precision over light emission periods may deteriorate
Solution Approach 1:
The invention segments the control function into two independent gate electrodes that can be controlled separately. The first gate electrode handles overall drive control while the second gate electrode provides precise light emission timing control. This segmentation allows independent optimization of each control aspect, maintaining high control precision despite using fewer transistors
Solution Approach 2:
The invention changes the control parameter from transistor count to gate electrode configuration. By adjusting the voltage applied to the second gate electrode, the threshold voltage of the transistor can be dynamically modified, enabling precise control of the light emission duty ratio. This parameter-based control approach maintains precision without requiring additional transistors
Data Source
AI summary
A display device includes: in a display region, a first scanning control line, a light emission control line, a data signal line, a pixel circuit provided at an intersection of the first scanning control line and the data signal line, and a light-emitting element provided for each of the pixel circuits; and in a non-display region, a first scanning control circuit and a light emission control circuit, wherein each of the pixel circuits includes a drive transistor, a write transistor, and a capacitor, the drive transistor including a first control terminal and a second control terminal positioned above and below a semiconductor layer, the light emission control circuit outputs, to the light emission control line, a light emission control signal that switches between a select state in which the drive transistor is turned on and a non-select state in which the drive transistor is turned off.