Passive Current Balance Driving Apparatus for LED Backlight Uniformity
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Solution Overview
Problem
Conventional current balance control circuits for LED backlight modules, such as those using MOSFETs or current regulation chips, have limited accuracy and result in excessive cost due to wasted regulation channels when driving multiple LED strings, leading to non-uniform luminance.
Innovation Solution
A passive current balance driving apparatus utilizing a transformer, capacitor, and diodes to equalize current flow through LED strings during AC power cycles, achieving identical load characteristics and balanced current distribution without active components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a current mirror circuit formed by MOSFET or current feedback compensation circuit is used to regulate current, then current balance can be achieved, but manufacturing precision is limited due to process variation in semiconductor devices
Solution Approach 1:
The patent replaces active semiconductor devices (MOSFET, IC chips) with passive electronic components (transformer, capacitor, diodes). This substitution eliminates the process variation issues inherent in semiconductor manufacturing, achieving superior current balance accuracy without being constrained by fabrication tolerances of active devices.
Solution Approach 2:
The patent uses inexpensive passive components (standard transformer, capacitor, and diodes) instead of expensive active regulation devices. These passive components have stable characteristics and are readily available, providing cost-effective current balance control with high precision.
2Manufacturing precision
If ready-made current regulation chips are used to regulate current through multiple LED strings, then current balance can be achieved, but device complexity and cost increase due to fixed regulation channels
Solution Approach 1:
The patent designs a universal current balance circuit using passive components that can regulate current through any number of LED strings connected in parallel. The transformer-based circuit provides multi-functional capability, eliminating the need for multiple dedicated regulation chips and their associated fixed channels.
Solution Approach 2:
The patent merges multiple current regulation functions into a single integrated passive circuit. Instead of using separate regulation chips for each LED string, the transformer and diode network combines all regulation functions into one unified structure, reducing overall device complexity.
3Manufacturing precision
If multiple current regulation chips are used to drive ten LED strings, then current balance can be achieved, but cost increases due to wasted unused regulation channels
Solution Approach 1:
The passive current balance circuit provides universal regulation capability that can accommodate any number of LED strings without requiring additional components. This eliminates channel waste by providing exactly the right number of regulation channels needed, no more and no less.
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 apparatus ensures equal current flow through multiple LED strings, providing uniform luminance and reducing fabrication costs compared to traditional active circuit solutions.
Implementation Method 1
The transformer includes a primary side and a secondary side. The primary side is adapted to receive an alternative current (AC) power.
Implementation Method 2
A cathode of the first diode is coupled to a second terminal of the capacitor, and an anode of the first diode is coupled to a reference potential
Data Source
AI summary
A passive current balance driving apparatus has a circuit topology composed by several simple passive components and is capable of driving a plurality of LED strings simultaneously. The present passive current balance driving apparatus is mainly configured such that each LED string has the identical load characteristics during the positive and negative half cycles of the AC power. As such, the currents flowing through the respective LED strings are basically/substantially equal, thereby achieving the current balance.