Dynamic Gamma Control for OLED Power and Contrast
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Solution Overview
Problem
The existing peak luminance control (PLC) method in organic light emitting display devices, such as RGBW OLEDs, often exceeds power consumption limits despite efforts to reduce power usage, necessitating an improvement to operate within these limits while maintaining perceptual picture quality.
Innovation Solution
An organic light emitting display device and driving method that include an average picture level (APL) calculation unit, current value calculation unit, peak luminance controller, programmable gamma unit, and data driver, which calculate and adjust gamma values to control luminance based on target current values, using fixed or variable gamma settings to manage power consumption and enhance contrast ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the peak luminance control (PLC) method is used to enhance contrast ratio and perceptual picture quality, then luminance of particular images is increased, but power consumption exceeds the limit level
Solution Approach 1:
The patent implements dynamic gamma voltage adjustment based on real-time APL calculation. The gamma voltage is dynamically modified according to the calculated APL value and target current value, allowing the system to adapt luminance output to match power consumption limits while maintaining perceptual quality. This dynamic adjustment resolves the contradiction by making luminance control flexible rather than fixed.
Solution Approach 2:
The patent changes the gamma voltage parameter based on APL calculations to control peak luminance. By calculating the APL of the current image and comparing the resulting current value against a target, the system adjusts the gamma voltage to either enhance or suppress peak luminance, thereby controlling power consumption while maintaining perceptual picture quality within acceptable limits.
2Reliability
If gamma voltage is increased to enhance perceptual picture quality, then contrast ratio is improved, but current value exceeds target current value
Solution Approach 1:
The patent employs a feedback mechanism where the APL calculation unit continuously monitors image characteristics, calculates the resulting current value, and feeds this information back to the PLC unit. The PLC unit then adjusts the gamma voltage accordingly to maintain perceptual picture quality while keeping current consumption within target limits. This closed-loop feedback system resolves the contradiction by continuously balancing quality and power consumption.
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 effectively manages power consumption within limits while enhancing the contrast ratio and perceptual picture quality by dynamically adjusting gamma values in response to calculated current values, ensuring the display operates efficiently and maintains high image quality.
Implementation Method 1
In the organic EL element, electrons and holes are injected into a light emitting layer from an electron injection electrode (or a cathode) and a hole injection electrode (or an anode), respectively, and excitons formed as injected electrons and holes are combined to emit light when shifted from an excited state to a ground state.
Data Source
AI summary
An organic light emitting display device includes: an APL calculation unit; a current value calculation unit output a first result value or output a second result value; a peak luminance controller configured to output a first luminance control signal based on a first gamma conversion value when receiving the first result value from the current value calculation unit and output a second luminance control signal based on a second gamma conversion value when receiving the second value from the current value calculation unit; a programmable gamma unit configured to output a gamma voltage; and a data driver configured to generate a data signal and supply the generated data signal to a display panel.