OLED Sub-Pixel Reference Voltage Compensation for Luminance Uniformity
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Solution Overview
Problem
Existing organic light emitting display devices face luminance deviations between sub-pixels due to manufacturing variations in driving transistors, leading to non-uniform luminance, especially at low grayscale levels, despite external compensation techniques.
Innovation Solution
An organic light emitting display device with a sensing mode to measure characteristic values of driving transistors and generate reference voltages for each sub-pixel, ensuring differential voltage-based operation to maintain uniform luminance across sub-pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a constant DC reference voltage is generated from an external voltage supply and supplied to all sub-pixels in common, then the device complexity is reduced, but luminance uniformity deteriorates at low grayscale levels due to threshold voltage variations in driving transistors
Solution Approach 1:
The patent divides the common reference voltage supply into individual sub-pixel reference voltage supplies. Each sub-pixel receives its own reference voltage generated based on its specific threshold voltage characteristics, thereby segmenting the voltage supply system to achieve uniform luminance across all sub-pixels while compensating for manufacturing variations in driving transistors
Solution Approach 2:
The patent applies local quality by generating reference voltages tailored to each sub-pixel's local characteristics. The reference voltage for each sub-pixel is adjusted according to its specific threshold voltage, creating localized voltage optimization that compensates for manufacturing deviations and ensures uniform luminance output across different sub-pixels
2Manufacturing precision
If external compensation techniques are used to sense characteristic variation of sub-pixels, then manufacturing precision of driving transistors is compensated, but luminance uniformity still deteriorates due to non-uniform reference voltage supplied to each sub-pixel
Solution Approach 1:
The patent implements feedback by sensing the threshold voltage characteristics of each driving transistor and using this information to adjust the reference voltage supplied to each sub-pixel. The sensing unit measures the characteristic variations, and this feedback is used by the voltage generation unit to create customized reference voltages that compensate for manufacturing deviations, thereby achieving both precision compensation and luminance uniformity
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the reference voltage parameter for each sub-pixel based on its measured threshold voltage characteristics. Instead of using a fixed reference voltage, the system varies the reference voltage parameter individually for each sub-pixel to compensate for manufacturing variations and achieve uniform luminance output
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 uniform luminance between sub-pixels and improves luminance uniformity at low grayscale levels by adjusting reference voltages based on sensed transistor characteristics, reducing luminance deviations.
Implementation Method 1
An organic light emitting display device includes an organic light emitting layer which emits light by recombination of hole and electron
Data Source
AI summary
An organic light emitting display device includes a display panel which is operated in a sensing mode or display mode and is provided with a plurality of sub-pixels, wherein each sub-pixel includes a driving transistor driven in accordance with a differential voltage between data and reference voltages, and an organic light emitting diode which emits light by a current flowing in accordance with driving of the driving transistor; a first memory for storing a characteristic value of the driving transistor sensed from the sub-pixel by the sensing mode; and a panel driver for generating the reference voltage based on the characteristic value of the driving transistor for the display mode.