Pixel Circuit Oxide Transistors for Low-Frequency Flicker Reduction
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Solution Overview
Problem
Existing pixel circuits in organic light emitting display apparatuses are vulnerable to screen flicker defects due to increased leakage currents at low driving frequencies, particularly in structures like the 6T1C configuration.
Innovation Solution
Incorporation of oxide transistors into the pixel circuit, along with a specific refresh and reset frame structure that includes initial, sampling, and emission durations, to stabilize the gate-to-source voltage of the driving transistor, thereby reducing flicker phenomena.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional pixel circuit (e.g., 6T1C structure) is used, then the circuit can be manufactured with existing processes, but leakage current increases at low driving frequencies causing visible flicker
Solution Approach 1:
The patent changes the material parameter of the transistor from conventional semiconductor to oxide semiconductor, which fundamentally alters the electrical characteristics to achieve ultra-low leakage current operation while maintaining stability at low driving frequencies
Solution Approach 2:
The patent employs oxide semiconductor material (such as IGZO - indium gallium zinc oxide) which combines the advantages of wide bandgap for low leakage with good field-effect transistor characteristics, creating a composite material solution that resolves the flicker issue
2Use of energy by moving object
If the driving frequency is lowered to reduce power consumption, then energy efficiency improves, but leakage current increases causing flicker defects
Solution Approach 1:
By changing the transistor material to oxide semiconductor, the patent enables the display to operate stably at low driving frequencies without suffering from increased leakage current, thus allowing reduced power consumption without sacrificing display stability
3Object-generated harmful factors
If oxide transistors are used to reduce leakage current, then flicker is minimized, but device complexity increases
Solution Approach 1:
The patent changes the material composition parameter of the transistor to oxide semiconductor, which intrinsically provides ultra-low leakage current properties without requiring additional circuit structures or components, thus minimizing flicker without significantly increasing device complexity
Data Source
AI summary
A pixel circuit can include a first oxide transistor, a second oxide transistor, and a driving transistor. The driving transistor can include a gate electrode, a source electrode and a drain electrode. A capacitor, the first oxide transistor, and the second oxide transistor are connected to the gate electrode of the driving transistor. The pixel circuit can further include an emission element and a first transistor connected to the source electrode or drain electrode of the driving transistor.