Display Device Gate Signal Modulation to Reduce Threshold Drift
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Solution Overview
Problem
The reliability of display devices is compromised due to changes in the threshold voltage of transistors over time, leading to malfunctions.
Innovation Solution
Implementing a gate signal for transistors that includes a combination of DC and AC signals, with specific voltage levels and duty ratios to minimize the change in threshold voltage, particularly using an AC signal with 0 V or higher voltages to counteract thermal degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a DC signal is continuously applied to the gate of transistors, then the transistor operates stably, but the threshold voltage changes over time causing malfunction
Solution Approach 1:
The patent applies periodic AC signals to the gate of transistors in addition to the DC signal. The AC signal has a frequency of 1 kHz to 100 MHz and an amplitude of 0.1 V to 10 V, creating periodic voltage variations that prevent threshold voltage drift while maintaining stable transistor operation throughout the display device's operational lifetime
Solution Approach 2:
The patent changes the electrical parameters of the gate signal by superimposing an AC component on the DC gate voltage. This parameter modification (adding voltage fluctuations) fundamentally alters the transistor's electrical characteristics, preventing threshold voltage changes without affecting the display quality or operational stability
Data Source
AI summary
A display device is disclosed that includes a pixel circuit, a light emitting element, and a driving circuit. The pixel circuit includes a plurality of pixel transistors. The light emitting element is electrically connected to the pixel circuit. The driving circuit is configured to provide a prescribed signal to the pixel circuit and includes a plurality of driving transistors. A gate signal is applied to a gate of at least one transistor among the plurality of pixel transistors and the plurality of driving transistors. The gate signal includes a first interval in which a DC signal is applied and a second interval in which an AC signal is applied. The second interval includes a first sub-interval in which a first voltage is applied and a second sub-interval in which a second voltage different from the first voltage is applied. The first voltage is a negative voltage and the second voltage is a positive voltage or about 0 V.