OLED Driving Method for Brightness Uniformity and Lifespan
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Solution Overview
Problem
Organic light emitting displays (OLEDs) suffer from brightness uniformity issues due to deterioration over time and temperature, leading to reduced image quality and faster degradation when driven with constant voltage digital methods.
Innovation Solution
A method of driving OLEDs that involves storing brightness characteristics, generating accumulated data for each pixel, determining maximum brightness, and controlling voltage and bit values to maintain uniform brightness across pixels, compensating for deterioration by adjusting gray scales and voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If digital driving method with constant voltage is applied to OLEDs, then brightness uniformity is improved by displaying image regardless of threshold voltage differences, but OLEDs deteriorate faster and brightness uniformity is compromised
Solution Approach 1:
The patent applies dynamic driving by varying the voltage applied to OLEDs based on their emission time and accumulated usage. Instead of constant voltage, the driving voltage is adjusted dynamically to compensate for deterioration, thereby extending OLED lifespan while maintaining brightness uniformity across pixels with different threshold voltages.
Solution Approach 2:
The patent changes the voltage parameter dynamically based on emission time and accumulated data. By adjusting the driving voltage according to each OLED's usage history and deterioration level, the system maintains brightness uniformity while preventing excessive deterioration, thus resolving the contradiction between brightness uniformity and OLED lifespan.
2Reliability
If OLEDs are driven with constant voltage, then digital driving provides brightness uniformity, but deterioration accelerates and brightness uniformity is reduced
Solution Approach 1:
The patent implements preliminary anti-action by proactively adjusting the driving voltage before significant deterioration occurs. By monitoring emission time and accumulated usage data, the system preemptively reduces voltage to counteract deterioration effects, thereby preventing brightness non-uniformity caused by accelerated degradation.
Solution Approach 2:
The patent uses feedback mechanisms by continuously monitoring emission time, accumulated data, and brightness characteristics. This feedback information is used to adjust the driving voltage dynamically, creating a closed-loop control system that maintains brightness uniformity while minimizing deterioration rate.
3Duration of action of stationary object
If emission time is increased to maintain image display, then brightness uniformity deteriorates due to OLED degradation, but reducing emission time affects display continuity
Solution Approach 1:
The patent applies dynamic voltage adjustment based on emission time to maintain brightness uniformity over extended operation periods. By continuously adapting the driving conditions to the current emission time and accumulated usage, the system enables long-term display operation while preventing the brightness non-uniformity that would otherwise result from OLED degradation.
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 approach ensures uniform brightness and extends the lifespan of OLEDs by maintaining initial brightness levels, reducing pixel degradation and improving image quality by adjusting voltage and bit values based on pixel deterioration.
Implementation Method 1
the organic light emitting displays display images using organic light emitting diodes (OLED) that generate light by the re-combination of electrons and holes
Data Source
AI summary
There is provided a method of driving an organic light emitting display capable of displaying an image with uniform brightness. The method includes storing a brightness characteristic corresponding to emission time of an organic light emitting diode (OLED), adding first data supplied in units of frames by pixels to generate accumulated data, extracting accumulated data of a pixel to which currently supplied first data is to be supplied and calculating maximum brightness corresponding to emission time of the extracted accumulated data, calculating maximum brightness corresponding to emission time of largest accumulated data among the accumulated data, controlling a bit value of the first data using maximum brightness of a pixel to which the first data is to be supplied and maximum brightness of the largest accumulated data to generate second data, and controlling a voltage value of a first power source supplied to the pixels in response to the maximum brightness of the largest accumulated data.