OLED Display Ambient Light Current Control
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Solution Overview
Problem
Conventional organic light emitting displays face challenges in maintaining consistent image brightness due to variations in ambient light, leading to perceived darkness or brightness issues, and high power consumption during high luminance, which affects image quality and contrast.
Innovation Solution
The implementation of an optical sensor and current controller system that adjusts the emission time and electric current based on peripheral light levels, using a gamma compensation circuit to control luminance across four levels, thereby optimizing current flow and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high luminance is generated to display images in high ambient light conditions, then image visibility is improved, but power consumption increases significantly
Solution Approach 1:
The patent implements dynamic luminance control by adjusting the emission time of pixels based on ambient light conditions and image content. The emission time is varied frame-by-frame and pixel-by-pixel to optimize power consumption while maintaining visibility, replacing static high luminance with adaptive dynamic emission timing
Solution Approach 2:
The system changes the emission time parameter dynamically based on ambient light levels and image characteristics. By modifying this temporal parameter rather than maintaining constant high luminance, the system achieves energy efficiency while preserving image visibility in varying ambient conditions
2Illumination intensity
If emission time is extended to improve image brightness, then luminance is improved, but power consumption increases
Solution Approach 1:
The patent applies partial emission action by activating only necessary pixels for the required duration. Instead of extending emission time for all pixels, the system selectively controls emission based on image content and ambient light, achieving adequate brightness with minimal power consumption
Solution Approach 2:
The emission time is dynamically adjusted rather than extended uniformly. The system optimizes the duration of emission for each pixel based on real-time conditions, preventing excessive power consumption while maintaining required brightness levels
3Illumination intensity
If high current flows through pixel portion to generate high luminance, then brightness is improved, but contrast deteriorates
Solution Approach 1:
The patent applies local quality control by adjusting emission time and current on a pixel-by-pixel basis rather than uniformly across the entire display. This localized control maintains contrast by preventing over-brightness in individual pixels while achieving required luminance where needed
4Adaptability or versatility
If ambient light varies, then adaptability to environment is improved, but image brightness consistency deteriorates
Solution Approach 1:
The system employs feedback control by sensing ambient light conditions and automatically adjusting emission time and gamma characteristics. This closed-loop approach maintains image brightness consistency despite varying ambient light, achieving both adaptability and stability
Solution Approach 2:
The emission parameters are dynamically adjusted in response to ambient light changes. This dynamic adaptation maintains consistent image brightness across varying environmental conditions by real-time parameter optimization
Data Source
AI summary
An organic light emitting display and a method for driving the same is disclosed. A pixel portion includes a plurality of pixels, which receive a plurality of scan signals, a plurality of emission control signals, and a plurality of data signals to display images. A data driver for generating and transferring the plurality of data signals to the pixel portion using video data. A scan driver transfers the plurality of scan signals and the plurality of emission control signals to the pixel portion. An optical sensor controls luminance of the pixel portion according to peripheral (or ambient) light. A current controller limits an electric current flowing through the pixel portion according to a sum of the video data input during a frame when the peripheral light sensed by the optical sensor has luminance equal to or greater than a predetermined value in order to control the luminance.