Aspherical Lens Geometry for Mask-Free Automotive Headlamp Beam Control
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Solution Overview
Problem
Existing automotive lighting systems, particularly headlamp projectors, suffer from reduced performance due to the use of masks that obscure a significant fraction of the luminous flux, necessitating a more efficient and precise method to define light distribution without relying on masks or other obstructive elements.
Innovation Solution
A lighting module utilizing an aspherical projection lens, where the light beam shape is entirely defined by the lens geometry and the relative position of the light source, without a mask or cover, using an equation that adjusts the entrance surface to achieve the desired light distribution, allowing for the creation of dipped and main beams with improved energy efficiency and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a mask is used to define the shape of the light distribution, then the dipped beam and cut-off line can be created, but a significant fraction of the luminous flux (~50%) is obscured and energy efficiency is reduced
Solution Approach 1:
The patent extracts and removes the mask component from the optical system. Instead of using a mask to define the light distribution shape, the invention uses a freeform lens that directly shapes the light without obscuring any luminous flux, thereby eliminating the 50% energy loss associated with mask-based systems
Solution Approach 2:
The patent replaces the mechanical mask-based light shaping system with an optical freeform lens system. The complex polynomial surface of the freeform lens directly controls light distribution geometry, substituting the mechanical masking approach with an optical shaping approach that preserves all luminous flux
2Ease of operation
If a mask and reflector are used to define light distribution, then the dipped beam shape is achieved, but the mechanics of the module become complex and the size increases
Solution Approach 1:
The patent merges the functions of the reflector, mask, and lens into a single freeform lens component. The freeform lens integrates all light shaping functions that were previously distributed across multiple components, simplifying the mechanical structure and reducing the number of parts required
Solution Approach 2:
The freeform lens serves multiple functions simultaneously: it collects light from the source, shapes the light distribution, defines the dipped beam pattern, and creates the cut-off line. This multi-functional component replaces the specialized reflector and mask components, reducing overall system complexity
3Manufacturing precision
If a mask is used to create the dipped beam, then the cut-off line is defined, but the precision and homogeneity of the light beam are compromised
Solution Approach 1:
The freeform lens implements local quality variations across its surface through the complex polynomial equation, with different zones of the lens having different curvatures and refractive properties. This allows precise control of light rays at different locations to achieve both accurate beam shape definition and homogeneous light distribution
Solution Approach 2:
The patent uses parameter changes in the polynomial coefficients of the freeform lens surface equation to precisely control light distribution. By adjusting the polynomial parameters, the system achieves accurate beam shaping and homogeneous light output without the losses and imprecisions associated with mask-based systems
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 solution enhances the performance of headlamps by increasing energy efficiency, simplifying mechanics, reducing component count, and achieving better control over light distribution and homogeneity, while eliminating the need for a collecting reflector.
Implementation Method 1
a projection lens, said lens being obtained from the method as described above
Data Source
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AI summary
A method for defining an aspherical lens (120) having a predetermined optical axis, comprising an incident surface (121) capable of receiving a luminous flux from a light source (110) disposed at the focal point (F) of the lens (120) on the optical axis (x) and an exit surface (122) from which the rays of the luminous flux emerge having passed through the lens (120). The incident surface (121) is obtained by rotating a straight line about a vertical axis (z) perpendicular to the optical axis (x) of the lens (120) and the exit surface (122) is obtained after rotating the generating curve (124) about the optical axis (x), said generating curve (124) being calculated to direct the rays emerging from the exit surface (122) in a direction parallel to the optical axis (x). The method is characterised in that it consists of constructing the incident surface (121) from a substantially planar area (126) centred around the median plane (PM) of the lens (120), then adjusting this outcome for each radial section of the lens (120), from the median plane of the lens (120), until a cylindrical profile is obtained on the edge (123) of the lens (120).