Light Emitting Device Dimming via Segmented Light Source Control
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Solution Overview
Problem
Current light dimming methods for high-intensity light sources, particularly in digital projection and lighting applications, are inefficient due to light leakage and re-absorption, resulting in inadequate dimming control and reduced energy savings and light source lifespan.
Innovation Solution
A light emitting device with multiple light sources arranged at different distances from a light guide exit surface, where dimming is controlled by starting with the source furthest from the exit, allowing for precise adjustment of intensity levels and varying degrees of dimming by switching off or reducing light sources sequentially or in groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single light source is used with a luminescent material bar, then the device structure is simple, but the dimming control is inadequate and light leakage losses are high
Solution Approach 1:
The invention divides the light source into multiple separate light sources (at least two) positioned at different locations along the luminescent material bar. This segmentation allows independent control of each light source, enabling precise dimming levels that were not achievable with a single light source. The multiple light sources are controlled by a control device that can adjust their intensity individually or in groups, providing fine-grained dimming control while maintaining a relatively simple overall device structure.
2Area of stationary object
If the LED pump source is placed further from the exit surface to cover larger area, then the light distribution is improved, but light leakage and re-absorption losses increase
Solution Approach 1:
Instead of using a single LED positioned far from the exit surface, the invention segments the light source into multiple LEDs positioned at different distances from the exit surface. This allows the system to cover a larger area while maintaining shorter light paths for at least some of the light sources, thereby reducing light leakage and re-absorption losses. The control device can selectively activate only the light sources closest to the exit surface when dimming, further minimizing losses.
Solution Approach 2:
The invention applies different positioning strategies to different light sources based on their local requirements. Light sources positioned closer to the exit surface are used when minimal loss is required, while light sources positioned further away can be activated when broader light distribution is needed and some loss is acceptable. This local optimization of light source positioning and selection resolves the contradiction between area coverage and loss minimization.
3Illumination intensity
If multiple light sources are dimmed simultaneously, then the overall brightness is reduced, but energy savings are minimized due to inefficient dimming
Solution Approach 1:
The invention segments the light sources into controllable groups or individuals, allowing the control device to dim only the necessary number of light sources rather than dimming all simultaneously. This selective dimming approach maintains energy efficiency because the system can turn off or reduce intensity of light sources that are furthest from the exit surface (which contribute most to losses) while maintaining adequate brightness from light sources closer to the exit surface.
Solution Approach 2:
The control device can achieve the required dimming level by activating only a partial set of light sources (those closest to the exit surface) rather than activating all light sources at reduced intensity. This partial action approach is more energy-efficient because it avoids the losses associated with light from distant sources, even when those sources are dimmed. The system performs just enough action (activating necessary light sources) to achieve the desired brightness level.
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
This approach provides a more efficient and precise method for dimming, reducing energy consumption and extending light source lifespan by minimizing the number of sources dimmed simultaneously and optimizing light loss through the light guide.
Implementation Method 1
converting at least a part of the light with the first spectral distribution to light with a second spectral distribution
Implementation Method 2
guiding the light with the second spectral distribution to the first light exit surface
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A light emitting device, comprising at least two light sources (21, 22, 23, 24) adapted for, in operation, emitting light with a first spectral distribution, a first light guide (4) comprising a first light input surface (41), which is arranged parallel to the main waveguiding direction of the first light guide (4),and a first light exit surface (42)extending in an angle different from zero in relation to the first light input surface (41), the first light guide being adapted for receiving the light with the first spectral distribution at the first light input surface, converting at least a part of the light with the first spectral distribution to light (14) with a second spectral distribution, guiding the light (14) with the second spectral distribution to the first light exit surface (42) and coupling the light (14) with the second spectral distribution out of the first light exit surface (42), the at least two light sources (21, 22, 23, 24) being arranged at mutually different distances from the first light exit surface (42) of the first light guide (4), and a control device (90) adapted for dimming the light emitting device starting with the light source of the at least two light sources (21, 22, 23, 24) which is arranged at a largest distance from the first light exit surface (42) of the first light guide (4).