Integrated LED String Controller for PWM and Fault Monitoring
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Solution Overview
Problem
Conventional methods for controlling Infra-Red LED strings in driver monitoring systems require multiple controllers, increasing costs and causing electromagnetic interference, with limited flexibility and inadequate monitoring of current and short-circuit conditions.
Innovation Solution
A single controller with integrated boost and buck converters, PWM signal control, and multiple switch management for LED strings, along with monitoring and protection units to regulate current, brightness, and prevent short-circuits, reducing interference and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If multiple controllers are used to control multiple LED strings, then each LED string can be controlled independently, but the cost increases and electromagnetic interference increases
Solution Approach 1:
The patent combines multiple controller functions into a single integrated controller that can manage multiple LED strings. The controller includes multiple PWM output terminals (first PWM terminal, second PWM terminal, etc.) that can independently control multiple LED strings, eliminating the need for separate controllers while maintaining independent control capability.
Solution Approach 2:
The single controller is designed with multi-functionality to perform the roles of multiple separate controllers. It includes multiple PWM output terminals, current monitoring terminals, and protection terminals that can collectively manage multiple LED strings, making one controller capable of performing what previously required multiple dedicated controllers.
2Adaptability or versatility
If conventional resistor-based current control is used, then current can be adjusted, but flexibility is limited and costs increase due to uncommon resistance values or multiple shunt resistors
Solution Approach 1:
The patent replaces the conventional mechanical/resistor-based current control method with an electronic PWM control system. Instead of using resistors with uncommon values or multiple shunt resistors, the system uses PWM duty cycle adjustment to control LED string current, providing flexible and precise current regulation without requiring complex resistor configurations.
Solution Approach 2:
The patent changes the control parameter from fixed resistor values to variable PWM duty cycles. By adjusting the duty cycle parameter of the PWM signals, the system can flexibly control the current magnitude of LED strings without needing to change physical resistor components, enabling adaptive current control for different applications.
3Speed
If fast-changing current is used to regulate LED current, then current control responsiveness improves, but electromagnetic interference increases causing other electronic devices to malfunction
Solution Approach 1:
The patent uses PWM periodic action to control LED current. Instead of abrupt fast-changing current regulation, the system uses periodic switching with controlled duty cycles, which provides smooth current control while minimizing electromagnetic interference. The periodic nature of PWM allows for better EMI management compared to abrupt current changes.
4Reliability
If comprehensive monitoring and protection features are added, then system safety improves, but device complexity increases
Solution Approach 1:
The patent merges multiple monitoring and protection functions into the single integrated controller. It includes current monitoring terminals to detect LED string current, short-circuit monitoring terminals to detect faults, and protection terminals to prevent excessive current and inrush current. These functions that would traditionally require separate monitoring devices are combined into one controller, improving system safety without proportionally increasing complexity.
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 allows efficient, cost-effective control of multiple LED strings with reduced electromagnetic interference, flexible brightness adjustment, and comprehensive monitoring of current and short-circuit conditions, enhancing safety and performance.
Implementation Method 1
a first Light-Emitting Diode (LED) array and a second LED array
Implementation Method 2
a power input terminal operable for receiving electric power from a boost converter
Implementation Method 3
a power output terminal operable for providing electric power to the light source module through a buck converter
Data Source
AI summary
A controller for controlling a light source module including a first LED string and a second LED string includes a power input terminal operable for receiving electric power from a boost converter, a power output terminal operable for providing electric power to the light source module through a buck converter, a first input terminal operable for receiving a first pulse width modulation (PWM) signal, a second input terminal operable for receiving a second PWM signal, and a width monitoring terminal operable for receiving a width monitoring signal indicating a duration of a first state of the first PWM signal and a duration of a first state of the second PWM signal. The controller is operable for turning off the light source module if the width monitoring signal is greater than a width threshold signal.