Lighting Apparatus Current Feedback Balancing
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Solution Overview
Problem
Existing multi-lamp driving systems for LCD backlight modules face issues with current deviation and insufficient brightness uniformity due to characteristic errors in passive component-based current-balancing controllers, which also increase design costs and occupy more space on printed circuit boards.
Innovation Solution
A light source driving circuit with a balancing transformer that includes a power conversion circuit, load-driving coils with a common core, and a feedback generation coil, which synchronizes the driving of multiple light sources and generates a feedback signal based on electric and magnetic flux inductions to equalize load currents, reducing design costs and improving brightness uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If passive component-based current-balancing controllers are used, then current balance can be achieved, but characteristic errors cause current deviation and increase design cost
Solution Approach 1:
The patent employs a feedback mechanism where the feedback signal is taken from the high-side of the lamp through a feedback resistor, and this signal is used to control the switching element. This feedback loop automatically compensates for current deviations without requiring complex passive component matching, thereby reducing design cost while maintaining current balance precision.
2Device complexity
If feedback signal is taken from low-side of single lamp, then feedback control is simple, but current allocation becomes unequal across multiple lamps
Solution Approach 1:
The patent makes the feedback mechanism universal by taking the feedback signal from the high-side of the lamp, which allows the same feedback control scheme to be applied to multiple lamps simultaneously. This high-side feedback approach ensures that current allocation remains equal across all lamps while maintaining the simplicity of feedback control, as the feedback signal reflects the actual current flowing through each lamp.
3Manufacturing precision
If multi-lamp driving system with current-balancing controller is implemented, then current balance is attempted, but more space is occupied on printed circuit board
Solution Approach 1:
The patent merges the feedback resistor with the existing circuit structure by placing it in series with the lamp on the high-side. This integration eliminates the need for separate feedback components and reduces the overall PCB space occupation while maintaining the current balance function. The feedback path is combined with the power delivery path, reducing component count and board space.
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 balanced load currents across multiple light sources, enhancing brightness uniformity and reducing hardware costs by using a common core structure and feedback generation coil to adjust and stabilize the luminance of the light sources.
Implementation Method 1
the feedback generation coil generates a feedback signal to the power conversion circuit based on the inductions of the electric and magnetic flux generated by the currents flowing though the plurality of load-driving coils
Implementation Method 2
the plurality of load-driving coils shares a common core
Data Source
AI summary
A lighting apparatus comprises a plurality of light sources, a power conversion circuit, a plurality of load-driving coils and a feedback generation coil. The power conversion circuit generates a driving signal for the load-driving coils to generate substantially identical driving currents for driving every light source. Furthermore, the feedback generation coil generates a feedback signal based on the inductions of the currents flowing though the plurality of load driving coils.