OLED Display Current Control Circuit for Luminance Stability
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Solution Overview
Problem
Organic light emitting diode displays experience luminance changes and color distortion due to image display patterns and outdoor environmental conditions, primarily caused by IR drops and variations in driving current and voltage across red, green, and blue pixels, leading to inconsistent luminance and color representation.
Innovation Solution
The implementation of a display system with divided high-potential and low-potential driving voltage supply lines for R, G, and B pixels, accompanied by a current estimating circuit, current sensing circuit, and gamma power source control circuit, which generates and adjusts digital current values to maintain constant luminance by comparing estimated and sensed currents, ensuring accurate driving currents for each pixel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a voltage driving type is used for organic light emitting diode display, then the structure is simple, but IR drop causes luminance change and color distortion
Solution Approach 1:
The patent divides the power supply system into separate high-potential and low-potential driving voltage supply lines for different color pixels (R, G, B). This segmentation allows independent control and compensation of voltage drops for each color channel, preventing color distortion while maintaining overall system simplicity.
Solution Approach 2:
The patent implements feedback control by measuring actual driving currents and voltages, comparing them with target values, and adjusting the power supply accordingly. This feedback mechanism compensates for IR drops in real-time, maintaining consistent luminance across different display patterns without increasing structural complexity.
2Illumination intensity
If driving current is increased to compensate for IR drop, then luminance is improved, but power consumption increases
Solution Approach 1:
The patent employs dynamic voltage and current adjustment based on real-time measurements of display patterns and environmental conditions. Rather than using fixed compensation values, the system adaptively modifies driving parameters to maintain optimal luminance while minimizing power consumption under varying operating conditions.
Solution Approach 2:
The patent changes multiple parameters simultaneously including voltage levels, current magnitudes, and timing characteristics based on measured IR drops and ambient conditions. This multi-parameter optimization allows the system to achieve desired luminance levels while managing power consumption efficiently across different display scenarios.
3Reliability
If separate power supply lines are used for R, G, and B pixels, then color distortion is prevented, but device complexity increases
Solution Approach 1:
The patent designs the separate power supply lines to share common control logic and measurement infrastructure. The same control algorithm and sensing mechanisms are applied across all color channels, allowing the system to achieve color accuracy through standardized multi-functional components rather than entirely separate systems for each color.
4Reliability
If real-time current sensing and control is implemented, then luminance consistency is improved, but circuit complexity increases
Solution Approach 1:
The patent implements self-service control where the display system monitors its own performance and automatically adjusts its driving parameters. The built-in sensing circuits and control logic enable the system to compensate for its own deficiencies without requiring external intervention or complex external control systems.
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 effectively maintains consistent luminance across different image display patterns and outdoor conditions, preventing color distortion by ensuring that driving currents for R, G, and B pixels are adjusted to achieve desired luminance levels, thereby stabilizing color representation.
Implementation Method 1
If drive voltages are applied to the anode electrode and the cathode electrode, holes within the hole injection layer HTL and electrons within the electron transport layer ETL respectively move to the emission layer EML to form excitons. And, as a result, the emission layer EML emits a visible ray.
Data Source
AI summary
An OLED display including a display panel having a plurality of R, G, and B pixels formed and at least one of a high-potential and low-potential driving voltage supply line disposed; a data driving circuit; a gamma reference voltage generating circuit for generating gamma reference voltages for R, G, and B by dividing voltages of high-potential gamma power sources; a current estimating circuit for generating digital estimated current values for R, G, and B; a current sensing circuit for generating digital sensing current values for R, G, and B; and a gamma power source control circuit for controlling the high-potential gamma power sources by comparing the digital estimated current values for R, G, and B with the digital sensing current values for R, G, and B so that driving currents corresponding to the respective digital estimated current values flow in the respective R, G, and B pixels.