LED Lighting System Current Control via NTC Resistor Merging
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Solution Overview
Problem
Existing LED lighting systems are complex due to the requirement of three wires for connecting resistors in LED modules with power supply circuitry, making them difficult to manufacture and install.
Innovation Solution
A simplified LED lighting system with a power supply circuit that includes modulation circuitry, a current sensor, and a driver circuit, allowing communication of desired LED current without wires, and featuring a current source in each LED module to generate a sensor current multiplied by a constant factor, which is then supplied to the power supply circuit, enabling parallel connection of multiple modules with reduced complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If three wires are used to connect resistors in LED modules with power supply circuitry, then current control and temperature compensation are achieved, but device complexity and installation difficulty increase
Solution Approach 1:
The patent combines the current setting function and temperature compensation function into a single NTC resistor that is already present in the LED module. The NTC resistor serves dual purposes: it provides temperature compensation for the LED current and simultaneously carries the information about the desired LED current magnitude. This merging eliminates the need for separate current-setting resistors and reduces wire connections from three to two.
Solution Approach 2:
The NTC resistor is given multiple functions: it acts as both a temperature compensation element and a communication carrier for current magnitude information. By making the NTC resistor universal, the patent eliminates the need for dedicated current-setting resistors and reduces the complexity of wire connections while maintaining both temperature compensation and current control functions.
2Manufacturing precision
If three wires are used for resistor connections in LED modules, then accurate current control is possible, but ease of manufacture and installation deteriorates
Solution Approach 1:
The patent merges the current-setting function into the existing NTC resistor within the LED module. By utilizing the NTC resistor's temperature-dependent characteristics and its connection to the power supply circuit, the system achieves accurate current control without requiring additional current-setting resistors or extra wire connections, thereby simplifying the manufacturing process.
Solution Approach 2:
The patent extracts the current-setting function from a separate component (dedicated current-setting resistor) and integrates it into the existing NTC resistor. This extraction eliminates the need for additional components and wire connections, simplifying both manufacturing and installation while maintaining current control precision through the NTC resistor's inherent characteristics.
3Productivity
If multiple LED modules are connected in parallel, then total current is distributed across modules, but complexity of current management increases
Solution Approach 1:
The patent makes the NTC resistor universal by having it perform both temperature compensation and current magnitude communication functions. When multiple LED modules are connected in parallel, each module's NTC resistor independently communicates its desired current magnitude to the power supply circuit through the existing two-wire connection, eliminating the need for additional current management wiring or control circuitry for each module.
Solution Approach 2:
The patent implements a self-service mechanism where each LED module's NTC resistor automatically communicates its current requirements to the power supply circuit without external intervention. The power supply circuit automatically adjusts the total current based on the combined signal from all parallel-connected modules' NTC resistors, enabling automatic current distribution without complex external control systems.
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 solution simplifies the manufacturing and installation of LED lighting systems by eliminating the need for additional wires and allows for efficient current distribution across multiple modules, while also providing temperature-dependent current adjustment to prevent overheating.
Implementation Method 1
a second resistor NTC with a temperature dependent resistance
Implementation Method 2
modulation circuitry, coupled between the input terminals and the output terminals, for alternately maintaining the voltage between the output terminals at a high level during a first time interval and a low level during a second time interval
Implementation Method 3
a current sensor for sensing the current through the output terminals during the second time interval
Implementation Method 4
a LED load coupled between the LED module input terminals with a forward voltage that is higher than the voltage that is present between the output terminals of the power supply circuit during each second time interval
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a LED lighting system comprising a power supply circuit for supplying a LED current, equipped with input terminals (K1, K2) for connection to a supply voltage source and output terminals (K3, K4), modulation circuitry (MS, DC2), coupled between the output terminals, for alternately maintaining the voltage between the output terminals at a high level during a first time interval and a low level during a second time interval, a current sensor (R1, R2, S1) for sensing the current through the output terminals during the second time interval, and a driver circuit (DC1, DC2), coupled between the input terminals and the output terminals and coupled to the current sensor, for generating the LED current, out of a supply voltage supplied by the supply voltage source, wherein the LED current equals the current sensed by the current sensor multiplied by a predetermined constant multiplication factor and for supplying the LED current to the output terminals during each first time interval. The LED lighting system further comprises a LED module comprising LED module input terminals (K5, K6) for connection to the output terminals of the power supply circuit, a LED load (LS) coupled between the LED module input terminals with a forward voltage that is higher than the voltage that is present between the output terminals of the power supply circuit during each second time interval, and a current source (CS) coupled between the input terminals for, in case the LED module input terminals are connected to the output terminals of a power supply source, during each second time interval generating a sensor current through the current sensor that is equal to a desired LED current divided by the predetermined constant multiplication factor.