LED Driver Control Module for Below-Minimum Current Dimming
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Solution Overview
Problem
Discrete-spectrum light sources like LEDs and CFLs do not change color temperature when dimmed, causing an unnatural effect on the human eye, and existing LED drivers lack the capability to control current magnitude to a desired level, leading to inadequate load regulation.
Innovation Solution
A lighting control system comprising an LED driver and a control module that regulates output current magnitude and diverts a portion of the current away from LED light sources to achieve a desired color temperature and intensity, mimicking the behavior of black body radiators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If discrete-spectrum light sources (LEDs/CFLs) are used to replace incandescent bulbs, then energy efficiency is improved, but color temperature stability deteriorates when dimmed
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the drive current magnitude to the LED based on the requested intensity level. At different current levels, the LED emits light with different color temperatures, allowing the system to simulate the natural color shift of black body radiators. The control module modifies the electrical parameter (current) to achieve the desired optical parameter (color temperature) change.
2Reliability
If LED drivers regulate output current to a minimum level, then load regulation is improved, but the ability to achieve lower intensities deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the current control function into two stages: the LED driver handles current regulation down to its minimum level, while the control module handles further dimming by diverting portions of the driver's output current. This segmentation allows each component to operate within its optimal range while achieving a combined intensity range that extends below the driver's minimum.
Solution Approach 2:
The control module acts as an intermediary between the LED driver and the LED light source. It receives the regulated current from the driver, then selectively diverts portions of this current away from the LED using controllable switches. This intermediary function enables fine-grained intensity control below the driver's minimum regulation level.
3Adaptability or versatility
If a control module diverts current away from LED light sources, then intensity control below driver minimum is improved, but device complexity increases
Solution Approach 1:
The control module performs multiple functions: it controls the intensity of individual LED light sources, diverts current to achieve lower overall intensities, and regulates the cumulative light output of the lighting fixture. By making the control module multi-functional, the patent avoids adding separate dedicated circuits for each function, thereby limiting the increase in overall device complexity.
Data Source
AI summary
A lighting control system for controlling a cumulative light emitted by a lighting fixture may comprise a light-emitting diode (LED) driver comprising an output for conducting an output current, and a control module electrically coupled to the output of the LED driver for receiving the output current. The LED driver may regulate the magnitude of the output current towards a target current, and may be characterized by a low-end intensity. The control module may be coupled to a first LED light source of the LED light sources. The control module may receive a command including a requested intensity and control the magnitude of a first LED current through the first LED light source. The control module may control the cumulative light output of the lighting fixture below the low-end intensity of the LED driver by diverting a portion of the output current away from the first LED light source.