Pico Projector VLC Modulation for Color and Power Trade-offs
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Solution Overview
Problem
Pico projectors with RGB LED light sources face challenges in maintaining precise color performance due to temperature sensitivity, power wastage, and limited communication speed in visible light communication (VLC) applications, particularly in micro display systems.
Innovation Solution
A pico projector system integrating an LED light source with a digital micromirror device (DMD) that modulates the RGB light at a higher frequency for VLC communication, enabling multiple operation modes to enhance communication speed and power efficiency, including a high-speed mode that achieves up to 125 Gbps in FHD resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If RGB LED light source is used for pico projector, then color performance is improved, but temperature control difficulty increases
Solution Approach 1:
The patent implements periodic action by modulating the LED light source at a high frequency (second frequency) that is much higher than the display refresh rate (first frequency). This high-frequency modulation enables the LED to serve dual purposes: maintaining color performance for projection while enabling VLC communication. The periodic switching at high frequency allows the system to achieve both good color performance and temperature management through efficient duty cycle control.
2Illumination intensity
If LED light source is constantly on for projection, then lighting performance is maintained, but power consumption increases
Solution Approach 1:
The patent applies periodic action by implementing duty cycle control where the LED light source is modulated at a high frequency with specific on/off ratios. During VLC communication mode, the LED switches on and off rapidly at the second frequency, allowing the system to maintain lighting performance when needed while consuming less power during communication-only periods. This periodic operation enables the LED to be off during portions of the cycle, reducing overall power consumption while maintaining sufficient illumination when required.
Solution Approach 2:
The patent implements multi-functionality by enabling the LED light source to serve dual purposes: projection illumination and VLC communication. The same LED component performs both functions by operating at different frequencies or duty cycles depending on the mode. In projection mode, the LED operates at the display refresh rate for image projection. In VLC mode, the LED operates at the higher communication frequency. This universal usage eliminates the need for separate light sources for each function, thereby reducing overall power consumption.
3Speed
If high frequency modulation is applied for VLC communication, then communication speed is improved, but color stability deteriorates
Solution Approach 1:
The patent resolves this contradiction by implementing a dual-frequency periodic modulation scheme. The LED light source is modulated at a first frequency corresponding to the display refresh rate for maintaining color stability in projection mode, and simultaneously modulated at a second, much higher frequency for enabling VLC communication. The high-frequency modulation for VLC is superimposed on or coordinated with the lower-frequency projection signal, allowing the system to achieve high communication speeds while preserving color accuracy through the underlying projection synchronization.
Solution Approach 2:
The patent applies dynamics by making the LED modulation frequency adaptive based on the operational mode. The system dynamically switches between operating at the first frequency (display refresh rate) for projection-optimized color stability, and at the second frequency (higher frequency) for VLC-optimized communication speed. This dynamic frequency adjustment allows the system to optimize performance for the current operational requirement, achieving both color stability and communication speed as needed.
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 system effectively boosts VLC communication speed, conserves power, and maintains precise color performance by concurrently manipulating micro display arrays and LED light sources, achieving faster wireless communication while reducing power consumption.
Implementation Method 1
an LED light source for providing RGB color light of a first frequency for projection
Implementation Method 2
a digital micromirror device (DMD) modulated to selectively reflect the RGB light emitted by the LED light source
Data Source
AI summary
A pico projector with visible light communication has three different modes for various applications.