LED VLC Flicker Prevention via Data-Energy Interval Segmentation
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Solution Overview
Problem
Visible light communication systems using LEDs face challenges in preventing flickering, which can be perceived by the human eye due to fluctuations in light intensity during data transmission, and existing solutions may not reliably address this issue.
Innovation Solution
The implementation of a VLC system that interleaves data and energy intervals, where LEDs transmit data during designated data intervals and compensate with light emission during energy intervals, ensuring that the combined intensity appears constant to the observer, thereby preventing flickering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If LEDs transmit data by varying light intensity during data intervals, then data transmission is enabled, but light intensity fluctuations cause visible flickering
Solution Approach 1:
The patent segments the operation into distinct data intervals and energy intervals. During data intervals, LEDs transmit data with varied intensity; during energy intervals, LEDs emit light to compensate for energy consumption. This temporal segmentation allows the system to achieve both data transmission and flicker prevention by ensuring continuous light emission perceived by the human eye.
Solution Approach 2:
The patent implements periodic alternation between data intervals and energy intervals. This periodic structure ensures that within each complete cycle (data interval + energy interval), the LED provides both data transmission and sufficient light emission. The periodic nature with appropriate frequency ensures the flickering remains below human visual detection threshold while maintaining effective data communication.
2Object-affected harmful factors
If data transmission frequency is increased to prevent flickering, then flickering is reduced, but data transmission reliability may be compromised
Solution Approach 1:
The patent changes the parameter of interval duration to optimize both flicker prevention and data reliability. By carefully controlling the length of data intervals and energy intervals, the system ensures the combined cycle frequency exceeds human flicker fusion threshold while maintaining sufficient time within each interval for reliable data symbol transmission and energy compensation, thus achieving both goals simultaneously.
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 approach effectively prevents flickering by ensuring that the time periods for data and energy intervals are too short for the human eye to detect, maintaining a constant perceived light intensity and enhancing the reliability of data transmission in VLC systems.
Implementation Method 1
light sources (e.g., light-emitting diodes (LEDs)) to both transmit and receive data messages
Implementation Method 2
If the signal alternates between low and high intensity at frequencies higher than CFF, the observer does not perceive flicker
Data Source
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AI summary
LEDs that transmit or receive data in a VLC may create a flickering effect which is observed when the human eye is able to perceive the fluctuations of the light intensity in a LED. To prevent flickering, the LEDs may emit light based on a pattern of data and energy intervals. During the data intervals, a LED transmitting a message sends one or more data symbols to receiving LEDs. The receiving LEDs, however, are reversed bias and do not emit light. During the energy intervals, any LED in the VLC system may emit light. Each LED uses the energy interval to compensate for the light transmitted (or not transmitted) during the data interval. The combination of data and energy levels results in an observer seeing light with a constant intensity rather than changing intensity.