OLED Driving Circuit Voltage Drop Compensation
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Solution Overview
Problem
Existing display devices face challenges in maintaining uniform driving current to organic light emitting diodes (OLEDs) due to voltage drops in power source wires, leading to luminance deviations and image quality deterioration.
Innovation Solution
A light emitting driving apparatus with multiple transistors and capacitors is used to manage power source voltages and ensure uniform current flow to OLEDs, employing oxide thin film transistors and a specific driving method that includes initialization, threshold voltage compensation, and light emitting periods to stabilize the driving current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power source wires are used to supply voltage to OLEDs, then the display device can operate, but voltage drops occur in the wires causing non-uniform driving current and luminance deviations
Solution Approach 1:
The power supply system is segmented into multiple independent power source wires (first power source wire and second power source wire) that separately supply voltages to different nodes (first node and second node). This segmentation allows each wire to serve a specific function, reducing the voltage drop impact on the overall system and enabling independent optimization of each power supply path.
Solution Approach 2:
A voltage compensation circuit is introduced as an intermediary component between the power source wires and the OLED driving circuit. This circuit detects the voltage drops in the power source wires and actively compensates for them, ensuring uniform driving current flows to all OLEDs despite the presence of voltage drops in the wires.
2Reliability
If multiple power source voltages are applied to different nodes, then voltage drops can be compensated, but the device complexity increases
Solution Approach 1:
The first and second power source wires are configured to serve multiple functions: they not only supply voltages to different nodes for compensation but also work together with the voltage compensation circuit to maintain uniform luminance across all OLEDs. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity while achieving the desired luminance uniformity.
Data Source
AI summary
A light emitting driving apparatus includes light emitting driving blocks respectively having a first node applied with a second light emitting power source voltage, a second node applied with the first light emitting power source voltage, the second node being coupled to a relay signal output terminal outputting a relay signal, a third node applied with the first light emitting power source voltage, and applied with a third light emitting power source voltage, the third node being coupled to a reverse light emitting signal output terminal outputting a reverse light emitting signal, a first transistor turned on by a voltage of the first node to transmit the second light emitting power source voltage to a light emitting signal output terminal, and a second transistor turned on by a voltage of the second node to transmit the first light emitting power source voltage to the light emitting signal output terminal.