Organic EL Display Luminance Stabilization via Current Feedback
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Solution Overview
Problem
Organic electroluminescence display devices face challenges in maintaining constant luminance due to changes in temperature and time, which affect the operation point of organic EL elements, leading to variations in current passage and luminance.
Innovation Solution
A display device with a control unit that measures and corrects data voltage or current based on current variations, using derivation, measurement, and calculation processing to adjust video signals for each pixel, accounting for temperature and time changes, and varying correction coefficients by pixel position and color.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If organic EL elements are used in display devices, then the display can achieve high brightness and color quality, but the luminance varies due to temperature and time changes affecting the operation point
Solution Approach 1:
The patent implements a feedback mechanism where the operation point detecting circuit continuously monitors the actual operation point of the organic EL element, and the operation point correcting circuit adjusts the drive current based on detected deviations. This closed-loop feedback system compensates for temperature and time-induced shifts, maintaining stable luminance despite environmental changes.
Solution Approach 2:
The patent dynamically changes the drive parameters (current magnitude and pulse width) based on detected operation point shifts. By adjusting these parameters in response to temperature and time variations, the system maintains constant luminance output despite changes in the organic EL element's electrical characteristics.
2Reliability
If correction circuits are added to maintain constant luminance, then luminance stability improves, but device complexity increases
Solution Approach 1:
The patent combines the operation point detecting circuit and operation point correcting circuit into an integrated correction system that works seamlessly with the existing drive circuitry. By merging these functions into a unified control architecture, the patent reduces overall system complexity while achieving luminance stabilization.
Solution Approach 2:
The correction circuits are designed to automatically detect and correct operation point shifts without external intervention. The system self-regulates by continuously monitoring its own performance and making real-time adjustments, eliminating the need for complex external control mechanisms.
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 ensures constant luminance across the display area despite temperature and time-induced changes in organic EL elements, by accurately adjusting drive currents to maintain consistent light emission.
Implementation Method 1
each pixel 31 is provided with an organic EL element 30
Data Source
AI summary
The present invention provides a display device comprising a display having an arrangement of a plurality of pixels, a drive IC for supplying to each pixel of the display data voltage or data current corresponding to a video signal fed from the outside, comparing/calculating unit for supplying the video signal to the drive IC, and a current monitor unit for measuring the total quantity of currents to have been passed through a plurality of pixels of the display. The comparing/calculating unit derives the sum of currents to be passed through each pixel of the display based on the values of the video signals for each pixel of the display, to correct the video signals for each pixel of the display based on the derived value and measurement value obtained by the current monitor unit.