Data Driver Brightness Uniformity Compensation
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Solution Overview
Problem
Conventional organic light emitting display devices face challenges in displaying images with uniform brightness due to non-uniformity in transistor threshold voltages and electron mobility deviations.
Innovation Solution
A data driver is designed with current sink units, voltage generators, digital-to-analog converters, and switching units to control currents and reset gray scale voltages using compensation voltages, ensuring uniform brightness by compensating for electron mobility deviations and threshold voltage non-uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional pixel circuits are used to control brightness, then the device structure is simple, but the brightness uniformity deteriorates due to transistor threshold voltage non-uniformity and electron mobility deviation
Solution Approach 1:
The patent applies preliminary action by measuring and storing compensation values for each pixel's threshold voltage and electron mobility characteristics before normal display operation. The data driver pre-calculates and stores correction data that compensates for device variations, which is then applied during data signal generation to achieve uniform brightness across all pixels despite manufacturing variations
Solution Approach 2:
The patent changes the electrical parameters (threshold voltage and electron mobility) of the transistors through compensation mechanisms. By measuring actual parameter deviations and applying correction voltages or adjusted current levels, the system compensates for parameter variations to achieve uniform brightness output across all pixels
2Measurement precision
If threshold voltage compensation is implemented through pixel circuit control, then threshold voltage non-uniformity is compensated, but electron mobility deviation remains uncorrected
Solution Approach 1:
The patent makes the data driver multi-functional by enabling it to perform both threshold voltage compensation and electron mobility compensation. The system measures and compensates for multiple types of device variations (threshold voltage and electron mobility) through a unified compensation mechanism in the data driver, rather than relying solely on pixel circuit structures
3Ease of manufacture
If no compensation mechanism is used, then the device complexity is low, but the brightness uniformity and display quality deteriorate
Solution Approach 1:
The patent implements self-service by enabling the display device to automatically measure and compensate for its own device variations. The system includes built-in measurement circuits that characterize each pixel's threshold voltage and electron mobility, and the data driver automatically applies compensation based on these measurements, eliminating the need for external calibration or manual adjustment
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 enables the display of images with substantially uniform brightness by compensating for electron mobility and threshold voltage variations, improving the overall display quality of organic light emitting display devices.
Implementation Method 1
The organic light emitting display device displays images using organic light emitting diode devices that generate light by re-combination of electrons and holes
Data Source
AI summary
A data driver capable of displaying images with a substantially uniform brightness, an organic light emitting display device using the same, and a method of driving the organic light emitting display device. The data driver includes a plurality of current sink units for controlling predetermined currents to flow through data lines, a plurality of voltage generators for resetting values of gray scale voltages using compensation voltages generated when the predetermined currents flow, a plurality of digital-to-analog converters for selecting one gray scale voltage among the gray scale voltages as a data signal in response to bit values of the data supplied from the outside, and a plurality of switching units for supplying the data signal to the data lines. The predetermined currents may be set equal to pixel currents that correspond to a maximum brightness.