VLC Transmitter Modulates LED Backlight Data
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Solution Overview
Problem
Existing visible light communication (VLC) systems face challenges in portable electronic devices due to the need for additional power-consuming auxiliary LED lamps and the inability of non-continuous LED light sources, such as those used in display panels, to provide continuous data transmission.
Innovation Solution
A VLC transmitter uses pulse-width modulation (PWM) of LED backlights to modulate a carrier signal with data during the ON pulses, allowing for continuous data transmission without significantly affecting the perceived brightness of the display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If auxiliary LED lamps are used for VLC, then data transmission is enabled, but power consumption increases
Solution Approach 1:
The LED backlight serves dual functions: providing illumination for the display and transmitting data for VLC. By modulating the backlight's brightness or color during operation, the system enables communication without requiring separate dedicated LED transmitters, thus eliminating additional power consumption for auxiliary components.
Solution Approach 2:
The existing LED backlight infrastructure is utilized for VLC purposes. The backlight naturally emits light that can be modulated to carry data signals, allowing the system to serve its own communication needs without external辅助设备, thereby avoiding extra power expenditure.
2Use of energy by moving object
If CCFL backlight is used, then continuous illumination is provided, but data transmission capability is lost
Solution Approach 1:
The patent replaces CCFL (cold-cathode fluorescent lamp) technology with LED (light-emitting diode) technology for the backlight. LEDs can be rapidly switched on and off or have their brightness modulated, enabling them to carry modulated data signals while maintaining continuous illumination perception, thus restoring VLC capability to the display system.
Solution Approach 2:
The LED backlight is modulated periodically to encode data transmission. By varying the backlight's intensity or color in periodic patterns that correspond to data bits, the system enables communication while the human eye perceives continuous illumination due to persistence of vision.
3Loss of information
If LED backlight is modulated for VLC, then data transmission is enabled, but display brightness uniformity deteriorates
Solution Approach 1:
The VLC modulation is applied only during specific time intervals or to specific regions of the display, rather than continuously across the entire backlight. This partial modulation approach allows data transmission while minimizing visible flicker or brightness variations, maintaining overall display quality.
Solution Approach 2:
The system dynamically adjusts the modulation depth and frequency of the LED backlight based on display content and operating conditions. By adapting the modulation parameters in real-time, the system optimizes both data transmission effectiveness and visual quality, preventing noticeable brightness non-uniformity.
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 and power-effective visible light communication by utilizing the existing LED backlights in display panels for data transmission, maintaining constant average brightness and avoiding the need for additional power-consuming components.
Implementation Method 1
A visible light communications transmitter combines a modulated carrier signal with a pulse from a pulse generator. The carrier signal is modulated according to data read from a buffer during the pulse.
Implementation Method 2
LED backlights can provide a wider range of colors and freedom for the user to change or select the type white point of the backlight
Data Source
AI summary
A visible light communications transmitter combines a modulated carrier signal with a pulse from a pulse generator. The carrier signal is modulated according to data read from a buffer during the pulse.