LED String Current Control Using Bias-Voltage Tap Nodes
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Solution Overview
Problem
Existing LED-based lighting systems for plants are costly and lack robustness in power control, particularly in simulating natural sunlight spectra, as they rely on conventional power supply voltage rails for control, leading to inefficiencies and high component costs.
Innovation Solution
An apparatus with a current-control system using bias-voltage tap nodes within the LED string to generate operating voltages, allowing for efficient current control independent of the main power supply voltage, reducing component costs and power losses, and enabling the use of low-cost, high-volume components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional power supply voltage rails are used for current control, then the control system can operate with standard components, but the component costs increase and power losses occur
Solution Approach 1:
The patent extracts the bias voltage generation function from the external power supply and relocates it to the LED string itself by tapping voltage at intermediate nodes. This eliminates the need for separate voltage rails and external power supplies, reducing component costs and power losses while enabling current control using only the LED string's inherent voltage drops.
Solution Approach 2:
The LED string serves multiple functions: it provides both the light output and the bias voltage for the current controller. By using the voltage drop across LED packages as the bias source, the system eliminates dedicated power supply components, achieving multi-functionality that reduces both cost and power consumption.
2Ease of manufacture
If external power supplies are used for current control, then the control system has sufficient power, but the component count and cost increase
Solution Approach 1:
The patent removes external power supply components by extracting the bias voltage directly from the LED string's operational voltage drop. This eliminates additional components that would increase cost and potential failure points, while the LED string itself continues to provide reliable power for control operations.
3Device complexity
If bias voltage is taken from external power supply, then the current controller has stable voltage, but the system requires additional power supply components
Solution Approach 1:
The patent merges the bias voltage generation function with the LED string operation itself. The voltage drop across LED packages, which is already present during normal operation, is combined with the current control function by using it as the bias source, eliminating the need for separate power supply components and improving overall power efficiency.
Solution Approach 2:
The LED string is designed to serve dual purposes: providing light output and generating the bias voltage for the current controller. This multi-functionality reduces system complexity by eliminating dedicated power supply components while maintaining stable voltage for control operations through the inherent voltage drop across the LED packages.
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 solution enables efficient power control of LED strings with reduced component costs, improved reliability, and the ability to simulate varying spectral qualities for plant growth, while eliminating the need for external power supplies and expensive wireless modules.
Implementation Method 1
a first LED string that includes a first plurality of LED packages connected in electrical series with one another
Implementation Method 2
the bias voltage is provided by a voltage drop across the one or more of the LEDs located between the bias-voltage tap nodes
Data Source
AI summary
Apparatuses of various forms and each having at least one LED string controlled by a current controller biased by voltage tap nodes in the LED string, and circuitry for implementing the same. In some implementations, circuitry made in accordance with the present disclosure includes a current controller and current-control circuitry. The current controller is biased by a voltage drop across one or more LEDs in an LED string and controls the current-control circuitry in a manner that controls the electrical current in the LED string. In some implementations, one or more additional LED strings and/or one or more other devices may be controlled directly or indirectly by operation of the current controller.