LED Control Module Protecting Against PWM Signal Variations
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Solution Overview
Problem
Existing lighting systems for motor vehicles using semiconductor light sources like LEDs face damage due to untimely variations in the control signal, leading to potential semiconductor junction damage and reduced safety from dazzling effects.
Innovation Solution
A control module that receives a first control signal, checks its ability to maintain a setpoint for the luminous flux or current, and generates a second control signal if necessary to adjust the duty cycle and peak current, ensuring the LEDs are protected from high-intensity currents while maintaining synchronization with the original signal frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the peak current is increased to ensure high intensity luminous flux, then the luminous flux intensity is improved, but the risk of LED damage increases when PWM control signal variations occur
Solution Approach 1:
The control module continuously monitors the PWM control signal and compares it against expected parameters. When variations or errors are detected (such as unexpected duty cycle changes or peak current deviations), the system activates protective measures by limiting the peak current to a safe value, thereby preventing LED damage while maintaining normal high-intensity operation under correct control conditions.
Solution Approach 2:
The control module performs preliminary validation of the PWM control signal before it reaches the LED driver circuit. By checking the control signal in advance and preparing protective current limiting measures, the system prevents potential damage before it can occur, rather than reacting after damage has happened.
2Illumination intensity
If the PWM frequency is increased to reduce perceptible pulsing, then the visual smoothness is improved, but the synchronization requirement with shutter glasses becomes more critical
Solution Approach 1:
The control module monitors the PWM signal frequency and duty cycle to ensure they remain synchronized with the shutter glasses operation. By providing feedback control, the system maintains the precise timing relationship needed for the high-frequency PWM signal to work effectively with the shutter glasses, preventing desynchronization even at elevated frequencies.
3Illumination intensity
If the duty cycle is increased to maintain average current, then the current intensity is improved, but the peak current exposure time increases leading to potential damage
Solution Approach 1:
The control module calculates the expected average current based on the PWM duty cycle and peak current settings. When it detects that the actual duty cycle deviates from the intended value (which would increase peak current exposure time), it activates protective measures to limit the peak current, thereby maintaining the intended average current while reducing the harmful exposure duration.
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 the risk of LED damage and enhances safety by ensuring consistent luminous flux and current intensity, while maintaining synchronization with shutter glasses to reduce dazzling risks.
Implementation Method 1
an electrical power supply control device is necessary to power a group of LEDs performing a given light function
Implementation Method 2
An LED emits light when a voltage of at least a threshold value, called forward voltage, is applied across its terminals
Implementation Method 3
by applying a PWM pulse width modulation signal ('pulse width modulation') having a given duty cycle and peak current, to the converter at cutting
Implementation Method 4
The human visual system is distinguished by a perception of the integral type and perceives, compared to a constant and non-pulsating luminous flux, a flux of constant but reduced luminous intensity
Data Source
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AI summary
The invention provides a method and control module suitable for controlling the electrical current supply to light sources with electroluminescent semiconductor elements. According to the invention, the supply current is pulsed at a predetermined frequency and complies with predetermined luminous flux or electrical current settings.