Organic EL Pixel Mobility Correction Circuit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In organic EL displays, variations in threshold voltage and mobility of drive transistors across pixels lead to non-uniform brightness, affecting screen uniformity.
Innovation Solution
A display device with a mobility correction function that adjusts signal potentials in pixels by negative feedback, using a series-connected drive transistor and light emitting device, and a switching transistor to maintain constant mobility correction times across pixels, even with varying threshold voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If drive transistors are used to control current in organic EL pixels, then current control and brightness gradation are achieved, but variations in threshold voltage and mobility cause non-uniform brightness across pixels
Solution Approach 1:
The patent applies preliminary action by performing mobility correction before the light emission period. A correction voltage is applied to the gate of the drive transistor during a correction period (before light emission) to adjust the transistor's mobility characteristics. This preliminary adjustment ensures that when the pixel subsequently emits light, the brightness is uniform across all pixels despite manufacturing variations in transistor parameters.
Solution Approach 2:
The patent implements feedback by measuring the actual mobility of drive transistors and applying correction voltages based on these measurements. The system determines the mobility correction amount according to measured mobility values and applies appropriate correction voltages to compensate for mobility variations. This closed-loop feedback mechanism ensures uniform brightness by continuously adjusting for transistor parameter deviations.
2Illumination intensity
If mobility correction is applied to correct brightness uniformity, then screen uniformity improves, but additional control signals and timing coordination are required
Solution Approach 1:
The patent merges the mobility correction function with the existing pixel circuit structure by utilizing the same drive transistor and gate electrode. The correction voltage is applied through the existing gate terminal, combining the correction function with the driving function. This merging approach avoids adding separate correction circuits and reduces overall system complexity while achieving mobility correction.
Solution Approach 2:
The gate electrode of the drive transistor serves multiple functions: it controls the drive current during light emission and applies mobility correction voltage during the correction period. This multi-functionality allows a single component to handle both brightness control and mobility compensation, reducing the need for additional dedicated correction components and simplifying the overall device structure.
Data Source
AI summary
A display device is disclosed. The display device includes: a pixel array part; and a drive part that drives the pixel array part. The pixel array part includes row-wise first scan lines and second scan lines, column-wise signal lines, pixels arranged in a matrix form on parts where the lines intersect, and power supply lines and ground lines that supply power to the respective pixels. The drive part includes a first scanner that sequentially supplies first control signals to the respective first scan lines and line-sequentially scans the pixels in units of rows, a second scanner that sequentially supplies second control signals to the respective second scan lines according to the line-sequential scan, and a signal selector that supplies video signals to the column-wise signal lines according to the line-sequential scan.