Cylindrical Light Guide for Non-Planar Exit Faces
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Solution Overview
Problem
Current lighting and signaling devices for motor vehicles require light guides with non-planar exit faces that cannot be achieved using traditional spherical cap designs, necessitating a more versatile optical solution.
Innovation Solution
A cylindrical light guide with a non-planar shape, featuring a reflection face included in a ruled surface and an exit face that can be a complex 3D curve, allowing for customizable output shapes and improved light distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a spherical cap light guide is used, then the light guide can guide light effectively, but the exit face is limited to planar or simple curved shapes
Solution Approach 1:
The patent transitions from traditional 2D planar exit faces to 3D non-planar exit faces by introducing a cylindrical coordinate system. The exit face is defined by a guide curve in the radial direction and a generatrix in the axial direction, creating a surface that extends in three dimensions. This dimensional expansion allows the exit face to assume complex shapes including annular, linear, and curved configurations that cannot be achieved with spherical cap geometry.
Solution Approach 2:
The light guide is divided into distinct functional zones: a light entry zone where light sources are positioned, a light propagation zone where light travels through the transparent material, and a light exit zone defined by the non-planar exit face. The cylindrical sheet structure separates the reflection function (internal surfaces) from the exit function (external face), allowing independent optimization of each zone's geometry.
2Adaptability or versatility
If the exit face is made non-planar, then design flexibility is enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent defines the exit face geometry through mathematical parameters in a cylindrical coordinate system. The guide curve is specified by radial position as a function of angular position, and the generatrix is defined by axial position as a function of radial position. These parametric definitions allow complex 3D shapes to be described using relatively simple mathematical functions, facilitating both design and manufacturing.
Solution Approach 2:
The cylindrical light guide structure serves multiple functions simultaneously: it guides light from the entry zone to the exit zone, provides structural support, defines the optical path through its geometry, and creates the non-planar exit face shape. The same cylindrical structure that enables 3D exit faces also facilitates manufacturing through rotational symmetry and standard cylindrical fabrication processes.
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 the creation of light guides with non-planar exit faces, enhancing design flexibility and achieving homogeneous illumination with adjustable luminous intensity, suitable for various vehicle lighting functions.
Implementation Method 1
The guide sheet is made of a transparent material whose refractive index is greater than the refractive index of the medium in which the lighting device is intended to be immersed, for example air. Thus, a light ray introduced into the thickness of the layer by its entry edge encounters the upper or lower guide faces with an angle of incidence relative to the normal "N" which is greater than a limit angle of refraction. The ray is then likely to be totally reflected by the guide faces.
Data Source
Figure 1~3
Figure 4~7
AI summary
The device has a light guide (3) for guiding a part of light emitted by a light source (2) i.e. radial radiation LED. The light guide has a reflection surface (6) for reflecting the light propagated in the guide towards an output surface (5). The light guide is in cylindrical ply shape and made by molding a plastic material. The light guide is arranged such that the light beam issued from the output surface is parallel to an optical axis of the device. An independent claim is also included for a method for fabricating a light guide.