LED Luminaire Light Guide Feedback Control
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Solution Overview
Problem
Conventional LED luminaires face difficulties in stably detecting light from multiple LEDs and adjusting chromaticity due to inefficient light transmission and individual control of red, green, and blue LEDs, leading to unstable mixed-color light emission.
Innovation Solution
An LED luminaire with a light emitting module, a lens unit including a light guide for efficient light transmission to a light sensor, a light output controller for feedback control based on detected light levels, and a memory unit for storing reference values to adjust chromaticity, along with a light sensor using color filters or spectroscopic elements for precise light level detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical fibers are used to transmit light from each LED to the photodiode, then individual LED light output can be detected, but stable light detection from all LEDs becomes difficult
Solution Approach 1:
The patent combines the light from multiple LEDs through a light guide to a single photodiode detector, merging the optical paths. This eliminates the need for separate optical fibers for each LED, stabilizing light detection while maintaining the ability to measure overall light output for chromaticity control.
Solution Approach 2:
The light guide serves multiple functions: it transmits light from multiple different colored LEDs simultaneously to a single photodiode, enabling both individual LED detection and overall mixed light detection through the same optical path.
2Ease of operation
If red, green, and blue LEDs are driven individually at short intervals for control, then individual LED light output levels can be determined, but adjustment of mixed-color light chromaticity becomes difficult
Solution Approach 1:
The patent implements feedback control where the photodiode detects the actual light output from the mixed-color LEDs, and this detection signal is fed back to the drive circuit. The drive circuit adjusts the drive signals for each LED based on the feedback to achieve the desired chromaticity, enabling precise mixed-color control.
Solution Approach 2:
The system stores reference values for desired chromaticity in advance, and uses these pre-stored references to guide the feedback control process, enabling the system to know the target state before adjustment begins.
3Device complexity
If a single photodiode is used to detect light from all LEDs, then device complexity is reduced, but accurate detection of specific color light levels becomes difficult
Solution Approach 1:
The patent uses a light guide with different optical path lengths for different colored LEDs. The light guide is designed with specific optical properties at different locations, allowing the single photodiode to receive light signals that encode information about individual LED contributions, enabling specific color detection through spatial differentiation in the optical path.
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
Enables accurate adjustment and stabilization of mixed-color light chromaticity, ensuring consistent and uniform light emission across a wide range, matching ambient light conditions by controlling electric current to LEDs based on detected light levels.
Implementation Method 1
a light guide for guiding the mixed-color light from the lens to the light sensor
Implementation Method 2
a lens unit having a lens for diffusing the mixed-color light from the light emitting module
Implementation Method 3
a light sensor for sensing the mixed-color light from the light emitting module
Implementation Method 4
The light sensor preferably includes a plurality of color filters each selectively passing the light of each specific color
Implementation Method 5
the light sensor may be composed of a spectroscopic element for spectrally diffracting the mixed-color light from at least one light-emitting module into the lights of the specific colors
Data Source
AI summary
An LED luminaire is provided with a light emitting module composed of plural kinds of LEDs emitting lights of different colors, a lens unit having a lens for diffusing the mixed-color light from the light emitting module, a light output controller for controlling electric current fed to each of the LEDs, and a light sensor for sensing the light from the light emitting module. The light output controller performs feedback control on the electric current fed to each of the LEDs based upon light levels of the sensed light, so that the light emitted from the light emitting module has desired chromaticity. The lens unit contains a light guide for guiding the light from the lens to the light sensor and can guide the light from the light emitting module to the light sensor with a high efficiency.