Display Device Photoconductive Element Threshold Voltage Compensation
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Solution Overview
Problem
Display devices with light-emitting elements face challenges in achieving uniform luminance due to variations in threshold voltage of thin film transistors and degradation of light-emitting elements over time, leading to uneven displays and increased complexity with multiple elements required per pixel.
Innovation Solution
A display device structure incorporating a transistor, a photoconductive element, and a light-emitting element, where the photoconductive element transitions from a high-resistance to a low-resistance state upon light emission, allowing current to flow from a power line to maintain light emission even after the transistor turns off, reducing the need for additional drive transistors and compensation circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a threshold voltage compensation circuit is added to each pixel to compensate for transistor threshold voltage variations, then luminance uniformity is improved, but the number of elements per pixel increases and pixel area increases
Solution Approach 1:
The invention extracts the threshold voltage compensation function from a separate compensation circuit and integrates it into the light-emitting element itself. The light-emitting element is designed to automatically compensate for threshold voltage variations through its inherent characteristics, eliminating the need for additional compensation transistors and capacitors in the pixel circuit.
Solution Approach 2:
The light-emitting element is given multiple functions: it not only emits light but also performs threshold voltage compensation. By making the light-emitting element universal, the patent eliminates the need for separate compensation circuits, thereby reducing the number of elements per pixel while maintaining luminance uniformity.
2Reliability
If a feedback type pixel circuit with a photoelectric conversion element is used to control drive current in response to luminance, then luminance stability is improved, but the device complexity increases due to additional transistors required
Solution Approach 1:
The invention implements a self-service mechanism where the light-emitting element automatically adjusts its own drive current based on its luminance output. The element uses its inherent photoelectric conversion capability to detect its own luminance and regulate the current flowing through it, eliminating the need for external feedback circuits and additional control transistors.
Solution Approach 2:
The patent merges the light-emitting function and the current control function into a single integrated element. The light-emitting element combines light emission, photoelectric conversion, and current regulation capabilities, thereby achieving luminance stability without requiring separate feedback circuitry and additional transistors.
3Duration of action of stationary object
If the transistor remains on to supply current to the light-emitting element, then continuous light emission is maintained, but power consumption increases and the transistor threshold voltage variations affect luminance uniformity
Solution Approach 1:
The invention employs periodic action by turning the transistor on and off in synchronization with the light emission cycles. The transistor is activated only when needed to initiate light emission and then turned off, relying on the light-emitting element's ability to maintain emission through its inherent characteristics, thereby reducing power consumption and eliminating threshold voltage variation effects.
Solution Approach 2:
The patent applies preliminary action by pre-configuring the light-emitting element with the capability to maintain light emission after the transistor is turned off. The element is designed to store or sustain the conditions necessary for continuous emission, allowing the transistor to be switched off while maintaining luminance uniformity不受 threshold voltage variations.
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 enables stable and uniform light emission without relying on the threshold voltage of the transistor, reducing the number of elements per pixel and improving image quality while maintaining light emission, thus addressing the issues of luminance variation and complexity.
Implementation Method 1
a photoconductive element including a first terminal and a second terminal, the first terminal connected to the second input-output terminal of the transistor and the second terminal connected to a first power line
Data Source
AI summary
A display device has a transistor including a gate terminal, a first input-output terminal and a second input-output terminal, the gate terminal connected to a scanning signal line and the first input-output terminal connected to a video signal line, a photoconductive element including a first terminal and a second terminal, the first terminal connected to the second input-output terminal of the transistor and the second terminal connected to a first power line, and a light-emitting element including a third terminal and a fourth terminal, the third terminal connected to the second input-output terminal of the transistor and the fourth terminal connected to a second power line.