LED Driver Circuit PWM Dimming Control
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Solution Overview
Problem
Existing lighting devices lack the ability to adjust light intensity, limiting user flexibility and energy efficiency, as they can only be turned on or off with a fixed default intensity.
Innovation Solution
A lighting apparatus comprising a light source, a rectifier circuit, a DC-DC converter, an adjustment circuit, and a controller that converts AC power to a variable direct current, allowing for adjustable light intensity through a PWM signal generated by a manual switch or external command, and optionally includes suppression and filter circuits for signal pattern modification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If LED lighting is used for energy-efficient illumination, then energy consumption is reduced and lifespan is extended, but the ability to adjust light intensity is lost
Solution Approach 1:
The patent implements dynamic light intensity adjustment by controlling the switching frequency of MOSFETs in the LED driver circuit. The controller varies the duty cycle of PWM signals to dynamically adjust the current supplied to LED modules, enabling continuous dimming from 0% to 100% intensity while maintaining energy-efficient LED operation throughout the adjustment range.
Solution Approach 2:
The system changes the electrical parameters (current magnitude, pulse width modulation duty cycle) supplied to the LED modules to achieve different light intensities. By varying these parameters without changing the fundamental LED operation mode, the patent maintains energy efficiency while gaining adaptability for different lighting conditions.
2Illumination intensity
If multiple LED modules are used to provide sufficient illumination, then light output is increased, but device complexity increases
Solution Approach 1:
The patent divides the lighting system into multiple independently controllable LED modules (first LED module, second LED module, etc.), each with its own current control circuit. This segmentation allows the system to achieve high light output by activating multiple modules while maintaining manageable complexity through modular design, where each module can be controlled individually or in combination based on lighting requirements.
Solution Approach 2:
The control circuit is designed to universally manage multiple LED modules using the same PWM control architecture. The same controller and MOSFET switching mechanism that controls a single module can be extended to control multiple modules, reducing overall system complexity through standardized multi-functional design rather than requiring separate control circuits for each module.
3Illumination intensity
If LED modules are activated continuously for maximum illumination, then light output is maximized, but lifespan is reduced
Solution Approach 1:
The patent implements periodic switching control of LED modules through PWM (Pulse Width Modulation) technique. Instead of continuous operation at maximum current, the MOSFETs switch on and off periodically with variable duty cycles. This periodic action reduces average current stress on LEDs while maintaining perceived brightness through persistence of vision, thereby extending LED lifespan while preserving light output capability.
Solution Approach 2:
The system maintains continuous useful lighting action through high-frequency PWM switching, where the LED modules operate continuously at reduced current levels or in alternating sequences. This continuous low-stress operation preserves LED lifespan while the rapid switching maintains continuous perceived illumination, eliminating the need for intermittent on/off cycling that would reduce lifespan further.
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
Enables users to adjust light intensity continuously within a range, extending the lifespan of the lighting apparatus by activating or deactivating LED modules and optimizing energy usage, while also allowing for wireless control of neighboring devices within the same group.
Implementation Method 1
a rectifier circuit, converts an AC power to a raw direct current
Implementation Method 2
The DC-DC converter converts the raw direct current to an output current according to a first duty ratio of the first PWM signal
Implementation Method 3
LED lighting, a solid-state lamp that uses light-emitting diodes as the source of light
Implementation Method 4
The light emitting diodes shows a new type of illumination
Data Source
AI summary
A lighting apparatus includes a light source, a rectifier circuit, a DC-DC converter, an adjustment circuit and a controller. The rectifier circuit converts an AC power to a raw direct current. The adjustment circuit provides an adjustment signal corresponding a light intensity setting of the light source. The controller is coupled to the DC-DC converter and the adjustment circuit. The controller receives the adjustment signal for generating a first PWM signal. The DC-DC converter receives the first PWM signal. The DC-DC converter converts the raw direct current to an output current according to a first duty ratio of the first PWM signal. The output current is supplied to the light source corresponding to the light intensity setting.