OLED Display Gate Line Segmentation for Threshold Voltage Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The life of OLED displays is reduced due to changes in the threshold voltage of the driving TFT, leading to unstable operation and varying current flow through the OLED, affecting display quality.
Innovation Solution
The OLED display employs a high potential driving voltage, a low potential driving voltage, and a sustain driving voltage, along with a switch circuit that controls the current flow through the OLED, isolating the current from the threshold voltage changes by using a storage capacitor and specific timing of scan pulses to maintain consistent operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional driving circuit with a single gate line is used, then the device complexity is low, but the threshold voltage changes cause unstable current flow and reduced display life
Solution Approach 1:
The gate line is divided into two separate gate lines (first gate line and second gate line) that are applied to different electrodes of the driving TFT. This segmentation allows independent control of the gate voltages, enabling compensation for threshold voltage changes and stabilization of the current flowing through the OLED, thereby improving display life without excessive complexity
Solution Approach 2:
The invention changes the voltage parameters applied to the two gate lines dynamically. The first gate line receives a first voltage and the second gate line receives a second voltage that are adjusted based on threshold voltage sensing and compensation mechanisms. This parameter change approach stabilizes the current flow through the OLED against threshold voltage drift, improving reliability
2Reliability
If the threshold voltage of the driving TFT is not compensated, then the device complexity remains low, but the current flow through the OLED becomes unstable affecting display quality
Solution Approach 1:
The invention implements a feedback mechanism where the threshold voltage of the driving TFT is sensed and compensated by adjusting the voltages on the two gate lines. The threshold voltage sensing circuit measures the actual threshold voltage, and this information is used to adjust the gate voltages accordingly, creating a closed-loop system that stabilizes the current flow through the OLED
Solution Approach 2:
The two gate lines act as intermediaries between the control circuit and the driving TFT channel. By applying different voltages to these two gate lines, the invention mediates the effect of threshold voltage changes on the current flow, allowing independent adjustment to compensate for threshold voltage drift and stabilize OLED operation
3Reliability
If a simple single-voltage gate control is used, then the ease of operation is high, but the display quality deteriorates due to varying current flow
Solution Approach 1:
The gate control is segmented into two independent voltage controls applied to different gate lines. This segmentation enables precise compensation for threshold voltage changes while maintaining relatively simple operation through standardized driving sequences and voltage levels that can be implemented with conventional display driving circuits
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 solution ensures that the current through the OLED is not affected by changes in the threshold voltage, thereby increasing the display's life and improving its quality by maintaining consistent current flow.
Implementation Method 1
When a driving voltage is applied between the anode electrode and the cathode electrode, holes that pass through the HTL 78d and electrons that pass through the ETL 78b, meet in the emission layer (EML) 78c to form excitons. As a result, the EML 78c generates visible rays.
Data Source
AI summary
An organic light emitting diode (OLED) display including a plurality of data lines to which a data voltage is supplied, a plurality of pairs of gate lines each comprising a first gate lines to which a first scan pulse is supplied and a second gate lines to which a second scan pulse partially overlapping the first scan pulse in an opposed phase is supplied, an OLED that emits light by current that flows between the high potential driving voltage source and the low potential driving voltage source, a driving device for controlling the current that flows through the OLED in accordance with a gate-source voltage applied between a gate electrode connected to a first node and a source electrode connected to the low potential driving voltage source, a storage capacitor connected between the first node and the second node, and a switch circuit.