OLED Pixel Brightness Correction via Anode Voltage Feedback
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Solution Overview
Problem
Conventional technologies for preventing burn-in in organic electroluminescence displays lack precise correction methods and require large data tables for voltage and current corrections, leading to inefficient brightness maintenance across pixels.
Innovation Solution
An image display device with detection means to identify deteriorated pixels, calculation circuits to determine differential voltages, and amplification mechanisms to apply non-linear light emission corrections, ensuring precise correction of self-light-emitting elements by adjusting image voltages based on the degree of brightness deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If feedback control on organic EL element driving voltage is performed based on current measurement through A/D conversion, then brightness stability is improved, but correction precision is insufficient due to lack of concrete signal feedback description and correction generation method
Solution Approach 1:
The patent implements a feedback control mechanism where the anode voltage of the organic EL element is detected and fed back to the signal driver circuit. The correction data storage unit stores correction values based on detected anode voltages, and these correction values are applied to adjust the image signal voltage. This closed-loop feedback system continuously monitors and corrects brightness deterioration, improving both stability and precision of correction.
Solution Approach 2:
The patent changes the parameter being controlled from current (in conventional methods) to anode voltage. By detecting anode voltage directly and using it as the basis for correction, the system achieves more precise control over the organic EL element's brightness characteristics. The correction values are specifically designed to compensate for voltage-induced brightness deterioration.
2Reliability
If terminal voltage measurement and comparison against default value is performed, then organic EL element driving current correction is achieved, but enormous size data table is required for voltage-current relation storage
Solution Approach 1:
The patent extracts only the essential parameter (anode voltage) needed for correction, eliminating the need to store comprehensive voltage-current relation data tables. By focusing solely on voltage detection and using pre-calculated correction values stored in compact memory, the system achieves reliable correction with minimal data storage requirements.
Solution Approach 2:
The patent performs preliminary detection of anode voltage characteristics and pre-calculates correction values that are stored in the correction data storage unit. These pre-computed correction values are ready for immediate application when brightness deterioration is detected, eliminating the need for real-time complex calculations or large data tables during operation.
3Illumination intensity
If constant current is applied to organic EL element, then initial brightness is achieved, but brightness deteriorates with time accompanied by anode voltage rise
Solution Approach 1:
The patent uses feedback control to continuously monitor the anode voltage of the organic EL element and apply corrective adjustments. The detected voltage changes are used to generate correction signals that compensate for brightness deterioration over time, allowing the element to maintain its initial brightness characteristics throughout its operational lifetime.
Solution Approach 2:
The patent dynamically adjusts the image signal voltage based on detected anode voltage changes. By changing the voltage parameter in real-time according to the element's aging characteristics, the system compensates for brightness deterioration and extends the effective operational duration while maintaining initial brightness levels.
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 enables accurate correction of brightness deterioration in organic electroluminescence displays, reducing burn-in and maintaining consistent pixel brightness, thereby enhancing display longevity and image quality.
Implementation Method 1
an organic electroluminescence element (hereinafter referred to as organic EL element)
Data Source
AI summary
Provided is an image display device in which deterioration of a self-light-emitting element within a pixel is corrected accurately. A detection unit detects, within a detection period, a difference in characteristics between self-light-emitting elements of adjacent pixels. A first subtraction circuit outputs a differential voltage between a reference voltage and an image voltage to a self-light-emitting element that is determined by the detection unit as a deteriorated element. An amplifier amplifies an output of the first subtraction circuit with a gain [1/{1-(α/100)}]1/2 when a driver transistor is driven in a saturation region. The amplifier amplifies the output of the first subtraction circuit with a gain [1/{1-(α/100)}] when the driver transistor is driven in a linear region. A differential between the reference voltage and an output of the amplifier obtained by a second subtraction circuit is used as a corrected image voltage.