LED Backlight Driving Module Using Series-Connected Isolation Transformers
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Solution Overview
Problem
Conventional edge-type LED backlight driving modules face issues with increased cost and complexity due to the number of LED light bars, interference from unsynchronized DC-DC converters, and additional electromagnetic radiation interference, as well as inefficiencies and overheating from linear current regulators and PWM dimming circuits.
Innovation Solution
The proposed LED backlight driving module uses a series connection of primary windings from multiple second power isolation transformers, coupled with a base voltage generation circuit to provide a negative voltage level, reducing the positive voltage level and ensuring uniform current across LED light bars, thereby eliminating the need for extra cooling and minimizing electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If DC-DC converters are used to drive each LED light bar, then the LED light bars can be driven with converted voltage signals, but the circuit board cost and area increase, and electromagnetic radiation interference occurs
Solution Approach 1:
The patent merges multiple DC-DC converter functions into a single power isolation transformer with multiple secondary windings. Instead of using separate DC-DC converters for each LED light bar, the invention uses one transformer to provide multiple isolated output voltages simultaneously, thereby reducing the number of components, circuit board area, and cost while maintaining voltage conversion capability for multiple LED strings.
Solution Approach 2:
The power isolation transformer is designed with multi-functionality to serve multiple LED light bars simultaneously. A single transformer unit provides isolated voltage conversion for multiple secondary windings, each connected to different LED light bars, eliminating the need for dedicated converters for each string and reducing overall system complexity.
2Adaptability or versatility
If DC-DC converters are used for voltage conversion, then the driving power signals can be adapted, but interference occurs if operation frequency is not synchronized with main power stage
Solution Approach 1:
By combining multiple voltage conversion functions into a single power isolation transformer synchronized with the main power stage, the invention eliminates frequency synchronization issues between separate DC-DC converters and the main stage. The transformer operates in unison with the main power stage, preventing electromagnetic interference while maintaining signal adaptation capability.
3Reliability
If linear current regulator and PWM dimming circuits are used, then the LED current can be stabilized, but power consumption increases and waste heat requires additional cooling fins
Solution Approach 1:
The patent replaces linear current regulator circuits with a resonant power supply system using power isolation transformers. This substitution eliminates the need for linear regulation that dissipates power as heat, achieving LED current stabilization through resonant power delivery instead, thereby reducing energy loss and eliminating the need for cooling fins.
4Illumination intensity
If the number of LED dies in series increases in each LED light bar, then the backlight brightness increases, but power consumption and waste heat of driving circuits increase
Solution Approach 1:
The invention replaces linear current regulators with resonant power supply circuitry that can efficiently handle higher voltage and power requirements. This allows increasing the number of LED dies in series for higher brightness without proportionally increasing power consumption and heat generation, as the resonant system maintains higher efficiency under increased load conditions.
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 achieves higher power conversion efficiency, reduces design costs, eliminates the need for additional cooling, and ensures uniform current distribution among LED light bars, while minimizing electromagnetic radiation and maintaining efficiency regardless of the number of LED dies.
Implementation Method 1
A second stage isolation transformer unit having a plurality of second power isolation transformers. The primary winding of each second power isolation transformer is interconnected one by one in series. The second stage isolation transformer unit is connected to the first secondary winding of the first stage isolation transformer unit in parallel. According to the first driving signal, a second driving signal with corresponding secondary winding of each second stage power isolation transformer is generated.
Implementation Method 2
The LED backlight driving module uses a base voltage generation circuit to provide a base voltage with a negative voltage level to reduce the positive voltage level of the second driving signal provided by the second stage power isolation transformer.
Data Source
AI summary
The instant disclosure relates to a LED backlight driving module. The driving module utilizes a plurality of second power isolation transformers interconnected to each other in series and connected to a secondary winding of a first power isolation transformer in parallel to produce a plurality of second driving signals with uniform current, and driving corresponding LED light bars with uniform brightness. Optionally, a base voltage circuit can be used to provide a base voltage with negative voltage level on the other end of LED light bars, so as to lower the positive voltage level of the second driving signals. Thus, it is beneficial that the LED backlight driving module provides higher power conversion efficiency and has lower design cost.