Colored LED Lighting Device for High-Frequency Li-Fi Data Transmission
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Solution Overview
Problem
Existing lighting devices using Li-Fi or VLC for data transmission are expensive, suffer from signal slowness due to phosphor inertia, poor electromagnetic compatibility, and high electrical loading, and are not suitable for constant brightness data transmission.
Innovation Solution
A lighting device with individually controllable colored LEDs that modulate light intensity between two wavelength ranges without changing the overall brightness, allowing for high-frequency data transmission with stable color and brightness, and a control device to manage this modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If white LEDs with phosphors are used for data transmission, then the lighting function is provided, but the phosphor inertia causes signal slowness and afterglow leading to reduced data transmission rate
Solution Approach 1:
The invention separates the lighting function and data transmission function by using different LED types. White LEDs provide continuous illumination while colored LEDs (without phosphors) handle high-frequency data transmission, eliminating the conflict between phosphor inertia and data rate requirements.
Solution Approach 2:
The invention combines multiple LED types (white LEDs for lighting, colored LEDs for data transmission) into a single lighting device, allowing both functions to coexist without interfering with each other's performance characteristics.
2Loss of information
If Manchester coding is used for data transmission with white LEDs, then data can be transmitted, but the constant switching on and off loads the electrical components
Solution Approach 1:
The invention uses pulse-width modulation (PWM) to dynamically control the colored LEDs, varying the duty cycle to encode data while maintaining average current levels that reduce electrical component loading compared to constant switching.
3Productivity
If high-frequency modulation is used for data transmission, then data transmission rate increases, but electromagnetic compatibility deteriorates
Solution Approach 1:
The invention uses colored LEDs as an intermediary for data transmission, which have faster response times than white LEDs with phosphors, enabling high-frequency modulation while the overall lighting remains stable, thus maintaining electromagnetic compatibility.
4Device complexity
If only white LEDs are used for both lighting and data transmission, then device complexity is reduced, but the lighting appearance changes during data transmission
Solution Approach 1:
The invention segments the LED population into white LEDs for lighting and colored LEDs for data transmission, allowing the white LEDs to maintain constant operation for stable lighting appearance while colored LEDs handle modulation without affecting overall color perception.
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
Enables efficient, high-frequency data transmission with stable color and brightness, reducing electrical loading and improving electromagnetic compatibility, while maintaining consistent lighting for primary illumination purposes.
Implementation Method 1
The lighting device has at least two individually controllable light sources, preferably LEDs, emitting light of different colors
Implementation Method 2
An information unit comprises or consists of an increase in brightness of a first wavelength range with a simultaneous decrease in brightness of a second wavelength range and a subsequent decrease in brightness of the first wavelength range with a simultaneous increase in brightness of the second wavelength range
Data Source
Figure 1~2
Figure 3~4
AI summary
Lighting device comprising at least two individually controllable light sources (10, 12), preferably LEDs, emitting light of different colors, and a control device (18) configured to transmit information units (26, 28) by means of the light sources (10, 12), wherein an information unit (26) comprises an increase in the brightness of a first wavelength range (14) while simultaneously decreasing the brightness of a second wavelength range (16) and a subsequent decrease in the brightness of the first wavelength range (14) while simultaneously increasing the brightness of the second wavelength range (16).