Single Current Source LED Driver with Non-Overlapping Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing LED lighting systems require multiple drivers and complex power stages to achieve both warm and cool color temperatures, leading to inefficiency and increased cost due to the need for multiple controller channels and power sources.
Innovation Solution
A lighting control circuit that uses a single current source and temporally non-overlapping drive signals to control multiple LEDs, allowing for a simple and inexpensive circuit that adjusts the duty cycle of drive signals to modify the relative lumen output of each LED or LED string, eliminating the need for individual LED drivers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple LED drivers and power stages are used to control different color temperatures, then the lighting system can achieve both warm and cool color temperatures, but the device complexity and cost increase significantly
Solution Approach 1:
The patent merges multiple LED driver functions into a single LED driver circuit. The driver alternately drives different LED strings (warm white and cool white) during different time periods within a switching cycle, eliminating the need for separate drivers for each color temperature. This combining approach reduces the number of power stages from three to one, directly resolving the contradiction between adaptability and device complexity.
Solution Approach 2:
The patent implements periodic switching control where the single LED driver alternates between driving different LED strings at different time periods. The controller switches the driver between different LED strings in a periodic manner, allowing one driver to perform the work of multiple drivers. This periodic action enables the system to achieve multiple color temperatures while using a single driver, resolving the complexity issue.
2Adaptability or versatility
If multiple LED drivers are used to control different LED strings, then each LED can be independently controlled, but the system efficiency decreases due to multiple power conversion stages
Solution Approach 1:
The patent combines multiple power conversion functions into a single power stage. Instead of having separate power conversion stages for each LED driver, the system uses one power conversion stage that serves all LED strings by alternately driving them. This eliminates redundant power conversion processes and reduces energy loss, directly addressing the contradiction between control capability and energy efficiency.
Solution Approach 2:
The single LED driver is designed to be universal, capable of driving multiple different LED strings with different color temperatures. The driver performs multiple functions by switching between different LED loads, replacing the need for dedicated drivers for each LED string. This multi-functionality reduces the total number of power conversion stages and improves overall system efficiency.
3Ease of operation
If multiple controller channels are used to control the lumen output of different LEDs, then precise control is achieved, but the cost and bulkiness of the control circuit increases
Solution Approach 1:
The patent makes the controller universal by enabling a single controller channel to control multiple LED strings. The controller generates switching signals that direct the single LED driver to different LED strings in a time-multiplexed manner. This allows one controller channel to perform the control function of multiple channels, reducing circuit complexity while maintaining precise lumen control through duty cycle adjustment.
Solution Approach 2:
The controller uses periodic switching to alternate between controlling different LED strings. By implementing time-multiplexed control where each LED string receives control signals during specific time periods within a switching cycle, the system achieves precise control of multiple LEDs using a single controller channel. This periodic control approach eliminates the need for multiple simultaneous control channels, reducing complexity while maintaining control precision.
Data Source
AI summary
A lighting control circuit (10) for controlling a plurality of LEDs (24, 26). The lighting control circuit (10) includes a current source (12) coupleable to a first LED (20) and a second LED (22); a first switch (24) configured to switch from an open position to a closed position when driven by a first drive signal (V3), wherein the first switch (24) is positioned to interrupt current flow (Iout) through the first LED (20) when the first switch (24) is in the open position; a second switch (26) configured to switch from an open position to a closed position when driven by a second drive signal (V4), the second drive signal (V4) being temporally non-overlapping with respect to the first drive signal (V3), wherein the second switch (26) is positioned to interrupt current flow (Iout) through the second LED (22) when the second switch (30) is in the open position.