OLED Brightness Compensation via Photo Sensor Feedback
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Solution Overview
Problem
Organic electroluminescent devices suffer from non-uniform brightness over time due to decay in brightness when operated for extended periods, leading to inconsistent performance in displays.
Innovation Solution
Incorporating a photo sensor coupled with a capacitor to adjust the voltage of a driving device based on the brightness of an OLED element, allowing for real-time compensation of illumination levels to maintain uniform brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If an OLED element is operated for a long period of time, then the device can maintain continuous illumination, but the brightness decays and becomes non-uniform
Solution Approach 1:
The patent implements a feedback mechanism where a photo sensor detects the actual brightness output of the OLED element and feeds this information back to a driving device. The driving device adjusts the current through the OLED element based on the detected brightness, compensating for decay and maintaining uniform illumination over extended operating periods.
2Illumination intensity
If the current through the driving device is increased to maintain brightness, then the illumination intensity is improved, but the brightness decay accelerates over time
Solution Approach 1:
The patent employs dynamic current adjustment rather than a fixed current level. The driving device continuously modifies the current through the OLED element based on real-time brightness feedback from the photo sensor, allowing the system to adapt to aging effects and maintain stable brightness without accelerating decay through excessive current.
3Illumination intensity
If a photo sensor and capacitor are added to compensate for brightness decay, then the brightness uniformity is improved, but the device complexity increases
Solution Approach 1:
The patent integrates multiple functions into existing circuit elements. The capacitor serves both as a timing element for the driving device and as a storage element for compensation charges. The photo sensor serves both as a brightness detector and as part of the feedback control loop, eliminating the need for separate compensation circuits and reducing overall 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 ensures improved brightness uniformity across OLED elements, enhancing the longevity and performance of organic electroluminescent devices by dynamically adjusting current flow based on detected brightness levels.
Implementation Method 1
A photo sensor is disposed overlying the sensitive area. An OLED element is disposed in the sensitive area and illuminating to the photo sensor
Data Source
AI summary
Organic electroluminescent devices are disclosed. A representative device incorporates a substrate that comprises a control area and a sensitive area. A switch device and a driving device are disposed overlying the control area. A photo sensor is disposed overlying the sensitive area. An OLED element is disposed in the sensitive area and illuminating to the photo sensor. A capacitor is coupled to the photo sensor and the driving device, wherein a photo current corresponding to the brightness of the OLED element is generated in the photo sensor responsive to the OLED element illuminating the photo sensor such that a voltage of the capacitor is adjusted by the photo current to control the current passing through the driving device, thus changing the illumination of the OLED element.