Multi-tone Driving for Visible Light Communication Transmitters
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional visible light communication systems using blue-light-excited-type white LEDs face limitations in transmission speed due to low response speed of fluorescent materials, leading to restricted data transmission rates and potential device damage from overcurrent, while also requiring complex circuit adjustments for optimal driving conditions.
Innovation Solution
A visible light communication transmitter employs a multi-tone driving method that generates driving current signals with specific pulse ratios and widths synchronized with transmission data, eliminating the need for a blue color filter and simplifying system configuration to achieve high-speed data transmission without device damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional driving methods are used with blue-light-excited-type white LEDs, then the system is simpler to implement, but the transmission speed is limited due to low response speed of fluorescent materials
Solution Approach 1:
The patent applies periodic action by using multi-tone driving signals with specific pulse widths and frequencies to excite the fluorescent material. By optimizing the periodicity and frequency components of the driving signal, the system achieves higher transmission speeds (up to 125 Mbps) while accounting for the response characteristics of the fluorescent materials, thus resolving the contradiction between speed improvement and system complexity.
Solution Approach 2:
The patent changes key parameters of the driving signal including pulse width ratios (α and β), frequency tones, and current amplitudes to optimize the excitation of fluorescent materials. By carefully adjusting these parameters, the system maximizes the response speed of the fluorescent material without requiring complex additional circuitry, thereby improving transmission speed while controlling device complexity.
2Productivity
If high current pulses are used to increase transmission speed, then data transmission rate improves, but device damage occurs due to overcurrent
Solution Approach 1:
The patent applies dynamics by implementing adaptive current control where the driving current amplitude and pulse width are dynamically adjusted based on the data being transmitted. The system uses different current levels for different signal states and optimizes pulse durations to ensure complete signal transmission within safe current limits, thereby achieving high data transmission rates without causing device damage from overcurrent.
Solution Approach 2:
The patent incorporates feedback mechanisms to monitor the actual current consumption and signal transmission quality. Based on this feedback, the system adjusts the driving parameters in real-time to maintain optimal transmission performance while preventing overcurrent conditions that could damage the LED or fluorescent materials, thus resolving the contradiction between productivity and device safety.
3Speed
If blue color filter is added to improve transmission speed, then response speed increases, but system complexity and manufacturing cost increase
Solution Approach 1:
The patent achieves improved response speed by optimizing the parameters of the driving signal rather than adding physical filters. By adjusting the pulse width ratios (α and β) and frequency characteristics of the multi-tone driving signal, the system maximizes the response of the fluorescent material to achieve high transmission speeds without requiring additional blue color filter components, thereby maintaining ease of manufacture and lower manufacturing costs.
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 enables efficient visible light data communication at speeds up to 125 Mbps with reduced bit error rates and prevents device damage by controlling current pulses within safe limits, while reducing system complexity and manufacturing costs.
Implementation Method 1
a blue LED with a fluorescent material that mainly emits a yellow light... the surrounding fluorescent material is excited by a blue light outputted from the blue LED disposed at the center and the light (mainly yellow) that is mainly complementary to blue is outputted from the fluorescent material
Implementation Method 2
the receiver converts the intensity of the light into an electric signal through a photoelectric converter such as a photo diode (referred to as a 'PD' hereinafter)
Data Source
AI summary
Using a general-purpose cost-advantageous blue-light-excited-type white light emitting diode (LED), destruction of devices is prevented and visible light data communication is performed at a sufficient transmission rate. The blue-light-excited-type white LED is driven based on a driving current signal generated based on transmission data. While a visible light signal is outputted to a receiver, a multi-tone driving current signal is generated by a rising pulse and a falling pulse to a rising edge and a falling edge of the transmission data, respectively. Each of pulse widths of the rising pulse and the falling pulse is the same as a unit interval of the transmission data.