OLED Pixel Voltage Control for Lateral Leakage
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Solution Overview
Problem
Organic light emitting display devices face challenges in accurately emitting single color or mixed color lights due to lateral leakage of driving current, resulting in inconsistent luminance that does not align with the desired gamma curve, especially when emitting colors other than white.
Innovation Solution
A display device and method that adjust the voltage levels of data and black voltages for peripheral pixels based on their light emission statuses, using a converter to correct grayscale values and set appropriate black voltages, ensuring consistent luminance across different color emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If grayscale voltages are set based on white color light gamma curve, then white color light luminance is accurate, but single color or mixed color light luminance does not accurately correspond to the gamma curve
Solution Approach 1:
The patent applies different black voltage levels to different pixel types (first color pixels vs. second color pixels) based on their specific emission characteristics. The converter adjusts black voltages locally for each pixel type rather than using a uniform voltage, enabling accurate luminance control for both single color and mixed color emissions while maintaining white color accuracy.
2Device complexity
If a single black voltage is used for all pixels, then device complexity is low, but luminance consistency across different colors is poor
Solution Approach 1:
The patent changes the voltage parameter by introducing multiple black voltage levels (first black voltage and second black voltage) to compensate for lateral leakage effects. The converter dynamically selects and applies appropriate voltage levels based on the emission status of neighboring pixels, thereby achieving consistent luminance across different color emissions without requiring complex hardware modifications.
3Object-generated harmful factors
If black voltage is increased to prevent lateral leakage, then current leakage is reduced, but luminance of non-emitting pixels increases when they should remain dark
Solution Approach 1:
The patent implements dynamic black voltage adjustment where the converter continuously monitors the emission status of pixels and adapts the black voltage level in real-time. When neighboring pixels are emitting light, a higher black voltage is applied to prevent lateral leakage; when they are not emitting, a lower black voltage is applied to keep non-emitting pixels dark. This dynamic approach resolves the contradiction between preventing leakage and maintaining proper black levels.
Data Source
AI summary
A display device includes: a pixel unit including a target pixel and peripheral pixels in a unit area set based on the target pixel; a converter configured to adjust a voltage level of a data voltage of the target pixel, based on light emission statuses of the peripheral pixels, and to determine a voltage level of a black voltage of at least one peripheral pixel which does not emit light among the peripheral pixels, based on the light emission statuses of the peripheral pixels; and a data driver configured to apply the data voltage to the target pixel, and to apply the black voltage to the at least one peripheral pixel which does not emit light.