Organic EL Display Voltage Drop and Brightness Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Active organic EL display modules face issues with uneven brightness due to variations in TFT characteristics and voltage drops caused by resistance components in power supply lines, leading to display unevenness, especially when vertical power supply lines have resistance components.
Innovation Solution
The solution involves a voltage drop correction unit that calculates and cancels voltage drops in power supply lines and a display unevenness correction unit that corrects brightness variations by using display data and pre-obtained correction data, with independent wiring terminals on the substrate and separated power supply lines connected to these terminals to reduce measurement time and prevent vertical resistance-induced unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If power supply lines are shared across multiple horizontal lines of pixels, then device complexity is reduced, but voltage drops cause display unevenness and brightness variation
Solution Approach 1:
The power supply lines are divided into multiple independent groups, with each group connected to a separate wiring terminal. This segmentation allows independent measurement and correction of voltage drops for each horizontal line, eliminating display unevenness caused by shared power supply lines while maintaining manageable device complexity.
2Productivity
If correction data is obtained by measuring all pixels simultaneously, then productivity is improved, but measurement precision decreases due to current interference between pixels
Solution Approach 1:
Pixels are divided into multiple groups based on their connection to different wiring terminals. Correction data is obtained by measuring each group separately while keeping other groups in a non-light-emitting state. This prevents current interference between pixels during measurement, ensuring high precision while maintaining efficient productivity through systematic group measurement.
Solution Approach 2:
The measurement process is performed periodically for each group of pixels in a sequential manner. Each group is measured during its designated time slot while other groups remain inactive, creating a periodic measurement cycle that eliminates mutual interference and ensures accurate correction data acquisition.
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 reduces measurement time for correcting display unevenness and eliminates the influence of vertical power supply line resistance, ensuring consistent brightness across the display panel.
Implementation Method 1
an organic EL element 3 having an anode connected to the drain of the drive TFT 1 and a cathode connected to a low voltage power supply CV
Data Source
AI summary
On a panel, a plurality of PVDD lines, each of which corresponds to a horizontal line of pixels and supplies power to the pixels of the horizontal line, are provided. A voltage drop correction unit that obtains a voltage drop before reaching the pixel, based on resistance in the plurality of power supply lines and currents flowing therein, and corrects display data so as to cancel the obtained voltage drop of the pixel. A display unevenness correction unit that corrects uneven brightness caused by a variation in a TFT characteristic of the pixel by performing a calculation using display data of the pixel and obtained correction data of the pixel.