LED Lighting Device Analog Current Control Flicker Elimination
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Solution Overview
Problem
Current LED-based color lamps struggle to produce a wide range of colors due to fixed 'on' and 'off' states of LEDs, leading to limited color combinations and stability issues with flickering at lower brightness levels, and require complex heat dissipation systems, increasing costs.
Innovation Solution
A lighting device using constant current sources controlled by potentiometers to adjust the current through red, green, and blue LEDs, allowing for continuous brightness adjustment from complete darkness to full illumination, eliminating flicker and enabling theoretically unlimited color combinations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If PWM is used to adjust LED brightness, then brightness can be varied, but flicker occurs at low brightness levels
Solution Approach 1:
The patent replaces the PWM pulse control mechanism with a direct analog voltage control mechanism. Instead of using pulse width modulation where duty cycle varies the effective brightness, the invention applies a continuous analog control voltage that directly modulates the LED current through a constant current driver circuit. This substitution eliminates the pulsed nature of PWM and provides continuous steady-state current to the LED, thereby eliminating flicker while maintaining brightness adjustability across the full range from complete darkness to full illumination.
Solution Approach 2:
The patent changes the control parameter from digital pulse duty cycle to continuous analog voltage level. By using an analog control signal that varies continuously in amplitude rather than in time-domain pulse width, the system achieves smooth brightness adjustment without the on-off cycling that causes flicker. The analog voltage directly controls the constant current driver to adjust LED current magnitude continuously, maintaining stable lighting at all brightness levels.
2Ease of operation
If voltage is used to control LED brightness, then control is simplified, but significant current variation occurs with small voltage changes
Solution Approach 1:
The patent introduces a constant current driver circuit as an intermediary between the analog control voltage and the LED. This intermediary component receives the simple analog control voltage and converts it into a precisely controlled constant current output. The constant current driver acts as a buffer that isolates the control circuit from the LED's nonlinear electrical characteristics, allowing simple voltage control while achieving precise current regulation. This intermediary stage linearizes the control relationship and eliminates the exponential current-voltage relationship inherent in direct LED control.
3Illumination intensity
If many LEDs are used for illumination, then illumination coverage is improved, but heat dissipation complexity and cost increase
Solution Approach 1:
The patent makes the LED array serve multiple functions: it provides both the primary illumination function and the color display function simultaneously. By using the same LEDs for both purposes through color mixing (combining red, green, and blue LEDs), the system eliminates the need for separate illumination LEDs and display LEDs. This multi-functionality reduces the total number of LEDs required, thereby reducing the overall heat generation and simplifying the heat dissipation requirements while maintaining both illumination and color display capabilities.
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 provides stable, flicker-free, and comfortable lighting with a wide range of colors, reducing costs by eliminating the need for complex heat dissipation and allowing for versatile lighting applications.
Implementation Method 1
The light source unit contains a number of red, green, and blue LEDs
Implementation Method 2
The constant current sources thereby provide various amount of constant current through the red, green, and blue LEDs of the light source unit respectively
Data Source
AI summary
A LED full-color lighting device contains a control unit, a light source unit, and a light display unit. The control unit relies on at least a potentiometer to apply various voltages to constant current sources, which in turn individually vary the current conducting through the red, green and blue LEDs of the light source unit, so as to deliver light of various colors. The colored light emitted from the light source unit can be easily and conveniently adjusted to fit a user's specific preference and mood. Colored patterns or textures can be formed on the light display unit so that the color of the light of the light source unit would mix with the colors of the patterns or textures to produce a visual effect as if some of the patterns or textures are changed.