Emission Control Stage Circuit for Stable OLED Low-Voltage Driving
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Solution Overview
Problem
Existing emission control drivers in OLED displays face challenges in maintaining stable voltage levels for emission control signals, leading to potential charging or discharging of capacitors when the emission control signal is at a low voltage.
Innovation Solution
A stage circuit design that includes an output circuit, input circuit, first, second, and third signal processors, and stabilizers to control node voltages, using transistors and capacitors to maintain voltage levels and prevent charging or discharging during low emission control signal states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the emission control signal is maintained at a low voltage, then power consumption is reduced, but the voltage stability for controlling the output may deteriorate
Solution Approach 1:
The circuit is divided into multiple functional stages: a first stage that generates the emission control signal at low voltage, and a second stage that separates the voltage control function into distinct nodes (first node for high voltage stability, second node for signal output). This segmentation allows the control signal to remain low voltage while maintaining stable voltage at the first node through dedicated voltage regulation components.
Solution Approach 2:
A buffer amplifier is introduced as an intermediary component between the low voltage emission control signal and the high voltage node. This buffer amplifier isolates the low voltage signal path from the high voltage stability requirement, allowing the first node to maintain stable high voltage while the second node outputs the low voltage control signal without mutual interference.
2Use of energy by moving object
If the emission control signal is maintained at a low voltage, then power consumption is reduced, but flicker phenomena may increase
Solution Approach 1:
The voltage at the first node is preliminarily stabilized to a high voltage level before the emission control signal is generated at the low voltage level. This preliminary voltage establishment ensures that when the low voltage signal is output, the voltage reference remains stable, preventing flicker phenomena during the low voltage operation period.
Solution Approach 2:
The buffer amplifier acts as an intermediary that decouples the low voltage signal path from voltage fluctuations. By isolating the emission control signal from direct connection to the high voltage node, the buffer prevents signal-induced voltage variations that would cause flicker, while still allowing the low voltage signal to control the output effectively.
3Reliability
If a capacitor is used in the stage circuit, then voltage stabilization is improved, but the capacitor may be charged or discharged during low voltage operation
Solution Approach 1:
The capacitor is strategically positioned to be connected only to the first node (high voltage node) rather than being directly connected to the low voltage signal path. This local connection ensures the capacitor stabilizes the high voltage node without being subjected to low voltage charging/discharging cycles, eliminating energy loss while maintaining voltage stabilization functionality.
Solution Approach 2:
The buffer amplifier serves as an intermediary that protects the capacitor from low voltage operation. The capacitor is placed in the high voltage domain separated from the low voltage signal path by the buffer, preventing the capacitor from being charged or discharged during low voltage emission control signal operation, thus eliminating energy loss.
Data Source
AI summary
A stage circuit including: an output circuit for supplying a voltage of a first or second power supply to an output terminal in response to voltages of first and second nodes; an input circuit for controlling voltages of the second node and a third node; a first signal processor for controlling the voltage of the first node; a second signal processor configured to control the voltage of the first node in response to an output voltage of a third signal processor and a signal supplied to a third input terminal; and the third signal processor for controlling the voltage of the second node. The third signal processor includes: a third capacitor coupled between the first power supply and the second node; and a third transistor coupled between the first power supply and the third input terminal, and including a gate electrode coupled to the second node.