Time-Division LED String Control for Uniform Conduction Time
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Solution Overview
Problem
Existing lighting systems struggle with non-uniform conduction time of light emitting elements due to fluctuations in drive voltage rise, leading to potential flickering.
Innovation Solution
A lighting control apparatus that drives multiple light source units in a time-division manner using a power supply circuit, switch elements, current detection, and a controller to ensure uniform conduction time by adjusting switch states based on current thresholds and timing corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a DC-DC converter supplies power to multiple LED strings connected in parallel, then power distribution is simplified, but conduction time becomes non-uniform causing flickering
Solution Approach 1:
The patent segments the parallel LED strings into individually controllable groups by introducing separate switch elements for each string. This allows independent control of conduction time for each string, enabling uniform lighting performance while maintaining the simplified parallel power distribution structure from the DC-DC converter.
Solution Approach 2:
The control circuit pre-calculates and sets the conduction time for each LED string based on its forward voltage characteristics before actual operation. By determining the appropriate conduction time in advance and implementing it through individual switch control, the system achieves uniform lighting without flickering while keeping the power distribution structure simple.
2Stability of the object's composition
If individual switches control each LED string, then conduction time can be controlled, but device complexity increases
Solution Approach 1:
The control circuit is designed to perform multiple functions: it detects the forward voltage of each LED string, calculates the appropriate conduction time, controls the individual switch elements, and ensures uniform lighting output. By consolidating these functions into a single control unit, the patent manages device complexity while achieving conduction time uniformity.
3Illumination intensity
If multiple light source units are driven simultaneously, then total light output increases, but current management becomes difficult leading to non-uniform conduction
Solution Approach 1:
The patent implements dynamic control of conduction time for each LED string based on real-time detection of forward voltage characteristics. The control circuit continuously monitors and adjusts the conduction time of each string individually, allowing multiple light source units to be driven simultaneously with precise current management, achieving both high total light output and uniform conduction.
Data Source
AI summary
To make conduction time (lighting time) of a light emitting element more uniform.A lighting control method in which a controller is used to drive a plurality of light source units connected in parallel to each other in a time-division manner, (a) where the controller includes: (b) to perform control of one switch element among a plurality of switch elements connected in series to each of the plurality of light source units to switch to a close state; (c) to start measuring a specified time when a current flowing through a current path between a power supply circuit and the plurality of light source units is equal to or greater than a threshold value; and (d) to perform control of the one switch element to switch to an open state when the specified time has elapsed.