Off-axis Collimation Optics for Adjustable LED Headlamp Beam Patterns
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Solution Overview
Problem
Current LED headlamp designs using photon funnels struggle to adjust the ratio of light between the narrow on-axis hotspot and off-axis background illumination, as the center lens typically directs one-third of the light to the hotspot and two-thirds to the background, limiting flexibility in achieving desired beam patterns.
Innovation Solution
The optical design modifies the TIR reflective back surface of the photon funnel to provide off-axis illumination, allowing for larger tilt angles and adjustable beam ratios by deviating from rotational symmetry, while maintaining unmodified cavity and exit surfaces, enabling control over both beam spreads and intensity patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the center lens is tilted to provide off-axis background illumination, then the beam tilt angle is achieved, but the beam width becomes relatively wide and cannot be made narrow
Solution Approach 1:
The patent segments the optical system into two distinct components: a center lens for on-axis hotspot collimation and a tilted TIR back surface for off-axis background illumination. This segmentation allows each component to independently control its respective beam characteristics without compromising the other, resolving the contradiction between achieving beam tilt and maintaining narrow beam width.
Solution Approach 2:
The patent introduces asymmetry by tilting the TIR back surface relative to the LED chip axis, while keeping the center lens symmetric and coaxial with the LED. This asymmetric configuration enables the off-axis background beam to achieve larger tilt angles while the symmetric center lens maintains a narrow on-axis hotspot, simultaneously satisfying both requirements.
2Illumination intensity
If the center lens collects light for off-axis beam, then the off-axis illumination is provided, but the light distribution ratio is fixed and cannot be adjusted
Solution Approach 1:
The patent makes the system dynamic by allowing independent adjustment of the TIR back surface tilt angle while keeping the center lens fixed. This dynamic adjustment capability enables flexible control over the light distribution ratio between on-axis and off-axis beams, adapting to different application requirements without fixed constraints.
Solution Approach 2:
The patent utilizes parameter changes by varying the tilt angle of the TIR back surface to control the amount of light directed into the off-axis beam. By changing this geometric parameter, the system can adjust the light distribution ratio between hotspot and background illumination, providing versatility for different lighting scenarios.
3Ease of manufacture
If the cavity side surface and light source are configured with rotational symmetry, then the manufacturing is simplified, but the beam configuration flexibility is limited
Solution Approach 1:
The patent applies local quality by maintaining rotational symmetry in the cavity side surface and center lens for ease of manufacture, while introducing asymmetry only in the TIR back surface tilt to achieve diverse beam configurations. This localized asymmetry approach preserves manufacturing simplicity while enabling flexible beam patterns for different applications.
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 allows for more flexible control over the angle and intensity of both on-axis and off-axis beams, enabling the redirection of all light into single or multiple beams with varying tilt angles, addressing the limitations of traditional designs.
Implementation Method 1
The majority of the light passes through the cavity side surface by refraction, is reflected by total internal reflection (TIR) at a back surface 102, and exits through the front surface 104 by refraction
Implementation Method 2
light passes by refraction through the center lens 103 and an exit surface
Implementation Method 3
the majority of the light passes through the cavity side surface by refraction
Data Source
AI summary
A light funnel collimator has a central lens surface and a back reflecting surface, shaped to provide a wider background beam and a narrower hotspot beam within but off-center of the wider beam. One of the beams is on-axis of the collimator, and the other beam is off-axis. The reflector is at least partly asymmetrical relative to the axis, and provides or contributes to the off-axis beam.