LED Driver Regulates Current via Input Power Feedback
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Solution Overview
Problem
Existing light emitting diode (LED) driving technologies using direct current (DC) power face challenges in maintaining consistent current regulation, particularly when dealing with varying input power and load conditions, which affects the efficiency and reliability of LED operation in applications such as backlight units for flat panel displays.
Innovation Solution
A light emitting diode driving apparatus that generates a reference voltage based on input power and a switching signal, using an auto gain controller, signal information extractor, and divider to maintain a constant average current supply to the LED, incorporating a rectifying unit, transformer, and comparator to stabilize the driving power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct current (DC) power is used to drive LED, then stable current regulation can be achieved, but the circuit becomes complicated
Solution Approach 1:
The patent replaces the mechanical DC power supply system with an AC power supply system combined with a rectifier and transformer. The AC-to-DC conversion is integrated into the power supply unit, eliminating the need for separate DC power supply circuits while maintaining stable current regulation through the controller's switching control and feedback mechanisms.
Solution Approach 2:
The controller performs multiple functions: it generates switching signals for the power switch, controls the transformer operation, regulates current to the LED, and provides feedback control. This multi-functionality consolidates what would otherwise require separate circuits into a single integrated control unit, reducing overall circuit complexity.
2Device complexity
If rectified power is used to drive LED, then circuit complexity is reduced, but current regulation characteristics deteriorate
Solution Approach 1:
The patent implements a feedback control mechanism where the controller monitors the current supplied to the LED and adjusts the switching signal accordingly. The controller receives feedback from the power supply unit and modifies the duty cycle of the switching signal to maintain constant average current, thereby improving current regulation characteristics while using rectified AC power.
Solution Approach 2:
The controller dynamically adjusts the switching frequency and duty cycle of the power switch based on real-time conditions. This dynamic control allows the system to maintain stable current regulation despite variations in input voltage or load conditions, overcoming the limitations of simple rectified power supply.
3Adaptability or versatility
If input power voltage varies, then adaptability is improved, but maintaining constant average current becomes difficult
Solution Approach 1:
The controller changes operating parameters (switching frequency, duty cycle) in response to variations in input voltage. When input voltage increases, the controller reduces the duty cycle to maintain constant average current; when input voltage decreases, it increases the duty cycle. This parameter adjustment enables the system to adapt to different voltage conditions while maintaining stable LED current.
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 ensures a constant average current is maintained to the LED, regardless of input power variations or load changes, enhancing efficiency and reliability, as demonstrated by the apparatus's ability to operate effectively across different voltage levels and duty cycles.
Implementation Method 1
a transformer (T) having a primary winding (P) receiving the input power, a secondary winding (S) electromagnetically coupled to the primary winding according to a preset turns ratio, receiving induced power, and providing the driving power to the light emitting diode
Data Source
AI summary
There is provided a light emitting diode driving apparatus capable of supplying a constant average current to a light emitting diode by generating a reference voltage used for driving the light emitting diode according to input power and a switching signal switching a path of a current supplied to the light emitting diode. The light emitting diode driving apparatus includes: a reference voltage generating unit generating a reference voltage set based on input power and a switching signal for supplying driving power to a light emitting diode; and a driving unit supplying the driving power to the light emitting diode according to the reference voltage.