OLED Voltage Limiting Circuit for Low Temperature Stability
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Solution Overview
Problem
OLED displays using the monitoring feedback method face picture quality defects due to unstable output voltage from the power IC in low temperature environments, leading to increased high potential driving voltages that can exceed the maximum output voltage, causing flickering phenomena.
Innovation Solution
Incorporating a voltage limiting part with zener diodes connected in parallel to the pixel monitoring part, which restricts feedback voltage levels to prevent exceeding the maximum output voltage of the power IC, ensuring stable high potential driving voltages are maintained within safe limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the high potential driving voltage is increased to compensate for brightness deterioration in low temperature environments, then the brightness is improved, but the output voltage exceeds the maximum output voltage of the power IC causing instability and flickering
Solution Approach 1:
The patent implements a feedback control mechanism where the voltage limiting part continuously monitors the feedback voltage from the pixel monitoring part and adjusts the high potential driving voltage accordingly. When the feedback voltage indicates that the driving voltage is approaching the maximum output voltage limit, the system automatically reduces the voltage increase rate or stops increasing it, preventing voltage instability and flickering while maintaining acceptable brightness levels in low temperature environments.
2Illumination intensity
If the feedback voltage is allowed to increase freely in response to temperature changes, then the brightness compensation is improved, but the voltage instability causes picture quality defects
Solution Approach 1:
The patent changes the operational parameters of the feedback control system by introducing voltage limiting thresholds. The voltage limiting part modifies the feedback voltage parameter to prevent it from exceeding predetermined limits corresponding to the maximum output voltage of the power IC. This parameter control ensures that brightness compensation occurs within safe operating ranges, maintaining picture quality while still adapting to temperature variations.
3Stability of the object's composition
If the monitoring feedback method is used to adjust driving voltage, then the brightness uniformity is improved, but the system complexity increases due to additional voltage limiting components
Solution Approach 1:
The patent introduces a voltage limiting part as an intermediary component between the pixel monitoring part and the power IC. This intermediary element simplifies the overall system architecture by providing a dedicated function for voltage constraint, rather than requiring complex control logic within the power IC or monitoring circuitry. The voltage limiting part acts as a buffer that automatically enforces voltage limits, reducing brightness uniformity issues without significantly increasing system complexity.
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 prevents picture quality defects by limiting feedback voltages, maintaining stable output voltages and preventing flickering, even in low temperature conditions, ensuring accurate gray scale display without exceeding the power IC's maximum output voltage.
Implementation Method 1
In order to resolve the above-mentioned problem, there is provided an OLED display which includes a display panel having an effective display area in which pixels displaying a gray scale are formed and a non-display area in which a pixel monitoring part monitoring a degree of deterioration of the pixels is formed, a power IC supplying a driving voltage to the display panel, and a voltage limiting part connected between the pixel monitoring part and the power IC to restrict voltage levels of feedback voltages supplied from the pixel monitoring part.
Data Source
AI summary
Embodiments of the invention provide an organic light emitting diode (OLED) display capable of preventing a defect of picture quality by instability of an output voltage of a power IC in a low temperature environment. The OLED display comprises: a display panel having an effective display area in which pixels displaying a gray scale are formed and a non-display area in which a pixel monitoring part monitoring a degree of deterioration of the pixels is formed, wherein each of the pixels includes an organic light emitting diode and a driving element; a power IC supplying a driving voltage to the display panel; and a voltage limiting part connected between the pixel monitoring part and the power IC to restrict voltage levels of feedback voltages supplied from the pixel monitoring part.