LED Operating Circuit Dimming Signal Harmonization
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Solution Overview
Problem
Conventional operating circuits for LEDs face challenges in maintaining constant current and minimizing ripple, leading to fluctuations in light spectrum and brightness, especially when operating multiple LEDs or during changes in load conditions.
Innovation Solution
The proposed operating circuit uses a control unit to generate a dimming signal by linking a low-frequency signal with a high-frequency signal, allowing for precise control of the switch-on and switch-off times of a first switch, with sensor units monitoring current and voltage to optimize the duty factor and minimize ripple, thereby maintaining constant LED power and brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional operating circuits are used to control LED brightness by regulating current flow, then brightness regulation is achieved, but current ripple fluctuates and light spectrum changes
Solution Approach 1:
The patent applies periodic action by using PWM (pulse width modulation) to control LED brightness. Instead of continuous current regulation that causes ripple, the system uses periodic pulse packets with constant current amplitude. The brightness is controlled by adjusting the frequency and duration of these pulse packets, while the constant current within each packet maintains stable light spectrum. This resolves the contradiction by replacing continuous current variation with periodic pulsing that maintains spectral stability while achieving brightness regulation.
Solution Approach 2:
The patent changes the control parameter from continuous current amplitude modulation to pulse width modulation. By keeping the current amplitude constant within each pulse packet and varying only the pulse width and frequency, the system achieves brightness regulation without current ripple. This parameter change resolves the technical contradiction by decoupling brightness control from current amplitude variation, thereby maintaining light spectrum stability.
2Productivity
If high-frequency switching is used to regulate LED current, then brightness control is achieved, but current ripple increases and affects light quality
Solution Approach 1:
The system uses periodic PWM pulse packets to achieve brightness control. By organizing the high-frequency switching into structured pulse packets with controlled duration and frequency, the system maintains responsive brightness control while the packet structure naturally limits ripple accumulation. The periodic nature of the pulse packets allows for better ripple management compared to continuous high-frequency switching.
Solution Approach 2:
The patent ensures continuity of useful action by maintaining constant current amplitude throughout each pulse packet. This continuous constant-current delivery within each packet minimizes ripple compared to on-off switching at every high-frequency cycle. The useful action (LED conduction) continues smoothly within each packet, reducing the harmful ripple effect while maintaining control responsiveness.
3Device complexity
If fixed switching times are used for LED operation, then circuit simplicity is maintained, but adaptability to load changes and LED failures is reduced
Solution Approach 1:
The patent introduces dynamics by making the PWM pulse packet parameters (frequency, duration, duty cycle) adjustable rather than fixed. This allows the control circuit to adapt to different load conditions, such as varying numbers of LEDs or LED failures, while maintaining relatively simple circuit architecture. The dynamic adjustment capability resolves the contradiction by adding flexibility without proportionally increasing circuit complexity.
Solution Approach 2:
The system incorporates feedback mechanisms that monitor LED operation and adjust PWM parameters accordingly. This feedback capability enables the circuit to adapt to load changes and component failures while maintaining simple overall architecture. The feedback loop allows automatic adjustment of switching parameters based on actual operating conditions, resolving the contradiction between simplicity and adaptability.
4Stability of the object's composition
If rapid switching sequences are used to minimize current ripple, then light spectrum stability is improved, but switching losses increase
Solution Approach 1:
The patent uses periodic PWM pulse packets to achieve light spectrum stability without excessive switching losses. By controlling the pulse packet frequency and duration, the system can maintain stable light spectrum (minimizing ripple) while reducing the number of switching operations compared to continuous high-frequency switching. This periodic approach resolves the contradiction by finding an optimal balance between spectral stability and switching loss.
Solution Approach 2:
The system applies partial action by using PWM pulse packets that activate the LED for only the necessary portion of the control period. Rather than continuous switching, the LED operates only during the pulse packet duration, reducing total switching losses while maintaining spectrum stability during the active periods. This partial action approach resolves the contradiction by reducing overall switching activity while maintaining quality during operation.
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 enables flexible operation of LEDs with reduced ripple and fluctuations, ensuring consistent light spectrum and brightness, even when the number of connected LEDs changes, by using a linked low-frequency and high-frequency signal to control the switch operation based on real-time sensor data.
Implementation Method 1
a supply voltage for at least one LED is provided by means of a coil and a first switch clocked by a control unit, wherein, when the first switch is switched on, energy is buffer-stored in the coil, which is discharged via a diode and via the at least one LED when the first switch is switched off
Data Source
AI summary
The invention relates to a method for activating at least one LED, which is supplied with a direct current voltage or a rectified alternating current voltage and which by means of a coil (L1) and a first switch (S1) clocked by a control/regulating unit (SR) provides a supply voltage for at least one LED, wherein when the first switch (S1) is switched on the coil (L1) temporarily stores energy that discharges via a diode (D1) and at least one LED when the first switch (S1) is switched off and wherein the control unit (SR) activates the first switch (S1) by means of a dimming signal. Said method is characterized in that the dimming signal is generated by externally combining a low-frequency signal and a high-frequency signal, wherein the pulse width (TON*LF) of the low-frequency signal is selected as an integral multiple of the cycle duration of the high-frequency signal.