OLED Regulator Sink Current Breaking Circuit
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Solution Overview
Problem
Existing regulators for OLED displays are weak in handling sink currents, leading to nonuniform threshold voltage compensation and degraded display quality due to variations in reference voltage.
Innovation Solution
A regulator with a sink current breaking circuit, including a p-type MOSFET buffer and a sink controller, that discharges sink currents to ground, maintaining a stable reference voltage and preventing input voltage swings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a regulator is used to generate reference voltage for OLED display, then the source current performance is improved, but the sink current handling capability deteriorates causing voltage instability
Solution Approach 1:
The regulator is divided into two independent current handling paths: one for source current (normal operation) and one for sink current (reverse current discharge). The sink current breaking circuit includes a dedicated discharge transistor and resistor that separate the sink current path from the main voltage regulation path, allowing each path to be optimized independently for its specific function.
Solution Approach 2:
A sink current breaking circuit acts as an intermediary between the regulator output and ground. This circuit includes a discharge transistor (fourth transistor) controlled by a sink controller that detects sink current conditions and activates a discharge path through a resistor to ground, mediating the harmful sink current before it can destabilize the reference voltage.
2Device complexity
If sink current flows in the regulator, then the regulator structure is simple, but the input and output voltages increase and reference voltage varies
Solution Approach 1:
The sink controller continuously monitors the regulator output for signs of sink current flow and activates the discharge transistor in advance to prevent voltage instability. The preliminary detection and activation mechanism ensures that sink current is neutralized before it can significantly affect the reference voltage, maintaining stability proactively rather than reactively.
Solution Approach 2:
The sink controller implements a feedback mechanism by monitoring the regulator output voltage and controlling the discharge transistor based on detected sink current conditions. When sink current is detected causing voltage deviation, the controller activates the discharge path, and when sink current stops, the controller deactivates the discharge path, creating a closed-loop feedback system that maintains voltage stability.
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
The solution ensures a stable reference voltage for OLED displays, improving display quality by uniformly compensating threshold voltages and reducing degradation.
Implementation Method 1
a p-type metal oxide semiconductor field effect transistor (MOSFET) that is connected between the output terminal and the ground level voltage source and discharges the sink current to the ground level voltage source
Data Source
AI summary
A regulator and an organic light emitting diode display including the regulator are disclosed. The regulator includes a reference voltage generating unit generating a reference voltage from an input voltage, a voltage division resistor circuit dividing a voltage of an output terminal of the regulator to generate a feedback voltage, a comparator comparing the reference voltage with the feedback voltage, a transistor that is turned on or off based on an output of the comparator and switches on or off the input voltage supplied to the output terminal, and a sink current breaking circuit for discharging a sink current flowing in the output terminal to a ground level voltage source.