Resin Headlight Lens with Diffraction Grating
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Solution Overview
Problem
Conventional projector type headlights with resin lenses face challenges in maintaining a grating shape and reducing color bleeding near the boundary line between light and shade, especially when the lens diameter is enlarged to 60 mm or more, due to molding inaccuracies and increased weight.
Innovation Solution
The use of two or three resin lenses with a diffraction grating on the lens face opposite to the light source, designed to cancel chromatic aberration, which reduces molding inaccuracies, enhances luminous intensity, and minimizes diffraction loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the projection lens diameter is enlarged to increase luminous intensity, then the luminous intensity is improved, but the weight increases and molding precision deteriorates
Solution Approach 1:
The projection lens is divided into multiple separate resin lenses (first resin lens, second resin lens, etc.) arranged in sequence on the optical axis. This segmentation allows each lens to have optimized, thinner wall thicknesses compared to a single large-diameter lens, reducing overall weight while maintaining the required aperture for high luminous intensity.
Solution Approach 2:
The patent uses resin materials with specific refractive indices and dispersion characteristics for different lenses. By selecting appropriate resin compositions and combining multiple lenses with different optical properties, the system achieves high luminous intensity transmission while controlling weight and maintaining molding precision.
2Illumination intensity
If the projection lens diameter is enlarged to increase luminous intensity, then the luminous intensity is improved, but the manufacturing precision deteriorates
Solution Approach 1:
By segmenting the projection lens into multiple smaller resin lenses, each lens can be molded with controlled wall thickness that avoids the sink and deformation problems associated with large single-piece molding. This enables precise reproduction of the diffraction grating shape in each lens during injection molding.
Solution Approach 2:
The patent optimizes the wall thickness parameters of each resin lens to be within specific ranges that prevent molding defects. By controlling the thickness of each individual lens rather than using a thick single lens, the system maintains high manufacturing precision for the diffraction grating pattern during injection molding.
3Object-affected harmful factors
If a diffraction grating is provided on the resin lens to cancel chromatic aberration, then color bleeding is improved, but the grating shape cannot be maintained when diameter is enlarged
Solution Approach 1:
The diffraction grating function is distributed across multiple resin lenses rather than being implemented in a single large lens. Each lens can be molded with precise diffraction grating patterns while avoiding the deformation and sink issues that plague large single-piece molding, thereby maintaining grating shape accuracy.
Solution Approach 2:
The patent controls the wall thickness of each resin lens containing a diffraction grating to specific ranges that prevent molding defects. This parameter optimization ensures that the diffraction grating shape is accurately reproduced during injection molding, maintaining the ability to cancel chromatic aberration without grating distortion.
4Weight of moving object
If resin material is used instead of glass to reduce weight, then weight is reduced, but molding precision deteriorates due to sink and deformation
Solution Approach 1:
By dividing the resin projection lens into multiple smaller lenses, each with optimized wall thickness, the patent eliminates the sink and deformation problems that occur in large single-piece resin molding. This segmentation enables high manufacturing precision while maintaining the weight advantages of resin material.
Solution Approach 2:
The patent optimizes the wall thickness parameters of each resin lens to fall within specific ranges that prevent molding defects such as sink and deformation. This parameter control allows resin lenses to be molded with high precision, matching or exceeding the quality of glass lenses while maintaining weight advantages.
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 configuration maintains the grating shape, improves color bleeding, and increases luminous intensity while reducing weight and molding time, even at larger diameters, compared to single resin lenses.
Implementation Method 1
the diffractive optical element has such characteristics on the contrary such that light of long wavelength (light of wavelength of reddish color) is well refracted and light of short wavelength (light of wavelength of bluish color) is not refracted
Implementation Method 2
color bleeding (referred to as color breakup as well) which originates in a chromatic aberration of the projection lens occurs in the vicinity of the boundary line between light and shade
Implementation Method 3
the dioptrics element has such characteristics that light of short wavelength (light of wavelength of bluish color) is well refracted and light of long wavelength (light of wavelength of reddish color) is not refracted
Data Source
Figure 1
Figure 2A~2C
Figure 3A~3B
AI summary
A projector type headlight (10) can include a projection lens (20) arranged on an optical axis extending in a longitudinal direction of a vehicle, and a light source unit (30) arranged on a more rear side than a back side focal plane of the projection lens (20), the projection lens (20) including resin lenses (22, 24) which are arranged on the optical axis. A resin lens (24) out of the resin lenses arranged closer to the light source unit (30) includes a diffraction grating (24c) provided on a lens face (S3) in a side opposite to a light source (30), the resin lens (24) out of the resin lenses arranged closer to the light source unit (30) has a lens face (S4) having a positive power, which is arranged in a light source side, and the diffraction grating (24c) is designed so as to cancel chromatic aberration of light emitted from the light source unit (30) and emitted forward through the resin lenses (22, 24).