LED Channel Current Control with Boosted Resistor Voltage
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Solution Overview
Problem
High-brightness LED lamps face power loss and EMI issues due to heat generation from channel resistors and rapid voltage changes during switching operations, making it challenging to maintain target current and reduce electromagnetic interference.
Innovation Solution
A lamp control device that boosts the channel resistor voltage using a booster circuit with pumping capacitors, adjusts the slope of the channel current through a ramp voltage generator, and varies the slope according to PWM dimming duty to minimize power loss and EMI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the number of LED channels is increased, then the illumination intensity is improved, but the power loss increases due to heat generation from channel resistors
Solution Approach 1:
The patent changes the voltage parameter by boosting the channel resistor voltage using a dedicated boosting circuit. This allows the channel resistor value to be reduced (changing resistance parameter) while maintaining sufficient voltage to drive the required channel current, thereby reducing power loss (I²R) while preserving illumination output
2Loss of energy
If the channel resistor value is reduced to reduce power loss, then the power loss is reduced, but the channel current control becomes difficult
Solution Approach 1:
The patent introduces a boosting circuit as an intermediary component between the voltage source and the channel resistor. This mediator boosts the voltage at the channel resistor to compensate for the reduced resistance value, ensuring that the product of current and resistance (voltage) remains sufficient for precise current control while still reducing overall power loss
3Productivity
If repeated switching operations are performed to drive LED channels, then the productivity is improved, but EMI increases due to rapid voltage changes
Solution Approach 1:
The patent applies preliminary action by pre-charging pumping capacitors before switching operations and using them to boost voltage during switching transitions. This preparatory energy storage smooths out rapid voltage changes during switching, reducing EMI while maintaining the ability to drive multiple LED channels efficiently
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 effectively reduces power loss by lowering the channel resistor value, maintains target current, and minimizes EMI by controlling the slope of the channel current, enabling precise current control even at varying dimming duties.
Implementation Method 1
a plurality of pumping capacitors, and configured to boost a channel resistor voltage applied to a channel resistor corresponding to the LED channel
Data Source
AI summary
Disclosed is a lamp control device. The lamp control device may include: a lamp having an LED channel; a channel resistor corresponding to the LED channel; and a controller configured to boost a channel resistor voltage applied to the channel resistor, and retain a channel current of the LED channel as a target current, using the boosted channel resistor voltage.