OLED Pixel Circuit Compensation for Luminance Uniformity
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Solution Overview
Problem
Organic light emitting display devices face issues with luminance uniformity due to differences in threshold voltages and mobility of driving transistors, leading to inconsistent driving currents and potential power consumption inefficiencies.
Innovation Solution
The implementation of a pixel circuit and organic light emitting display device that includes a capacitor to store voltages corresponding to threshold voltages and mobility compensation, allowing for consistent driving currents and reduced power consumption by compensating for transistor variations through a method involving multiple transistors and capacitors to manage data and reference voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple pixel circuit with basic transistor is used, then device complexity is reduced, but luminance uniformity deteriorates due to transistor characteristic variations
Solution Approach 1:
The pixel circuit performs preliminary compensation actions by storing threshold voltage and mobility information in capacitors before the actual display operation. The compensation transistor and multiple capacitors (first capacitor for threshold voltage, second capacitor for mobility) prepare correction values in advance, which are then applied to ensure uniform luminance output despite transistor variations.
2Manufacturing precision
If transistor characteristic compensation is implemented, then luminance uniformity is improved, but power consumption increases due to additional transistors and capacitors
Solution Approach 1:
The compensation function is segmented into distinct components: a compensation transistor for threshold voltage compensation, a first capacitor for storing threshold voltage information, and a second capacitor for storing mobility information. This segmentation allows each component to perform its specific compensation function efficiently, reducing overall power consumption compared to a monolithic compensation circuit.
3Use of energy by moving object
If transistor characteristic differences are not compensated, then power consumption is reduced, but driving current consistency deteriorates
Solution Approach 1:
The pixel circuit performs self-compensation for transistor characteristic variations using internally integrated components. The compensation transistor and capacitors work autonomously within the pixel to generate corrected driving currents, eliminating the need for external compensation circuits or additional power consumption at the system level.
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 solution improves luminance uniformity and reduces power consumption by ensuring consistent driving currents across pixels, enhancing the quality of displayed images and optimizing energy use in organic light emitting display devices.
Implementation Method 1
a capacitor holding the data signal supplied to the first transistor. In the capacitor, after a first voltage corresponding to a threshold voltage of the first transistor is stored, a second voltage resulted from compensating the first voltage for mobility of the first transistor is stored
Data Source
AI summary
The present disclosure relates to a pixel circuit and an organic light emitting display device that include an organic light emitting diode, a first transistor receiving a pixel power source in response to a data signal and supplying a driving current to the organic light emitting diode, and a capacitor holding the data signal supplied to the first transistor, and to a method of driving the pixel circuit and the organic light emitting display device. In the capacitor, after a first voltage corresponding to a threshold voltage of the first transistor is stored, a second voltage resulting from compensating the first voltage relative to mobility of the first transistor is stored, and a value obtained by adding a third voltage corresponding to the data signal to the second voltage in response to the data signal is stored.