Imaging Lens Final Surface Tilting to Diverge Ghost Light
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Solution Overview
Problem
The challenge is to prevent image quality deterioration caused by ghost light resulting from reflections between the final surface and the curved imaging surface in imaging lenses, particularly in mobile terminals where increasing lens complexity leads to issues with aberration correction and image quality.
Innovation Solution
An imaging lens with a lens group comprising six or more lenses, including at least one aspherical lens, where the final surface is a spherical or aspherical surface with non-inverted surface power and tilts towards the object side, ensuring a specific ratio of back focus to focal length to effectively diverge ghost light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the number of lenses is increased to improve lens performance and aberration correction, then imaging quality is improved, but the height of the imaging lens increases
Solution Approach 1:
The patent employs aspherical lenses within the lens group to correct aberrations and improve imaging quality without proportionally increasing lens height. The aspherical surfaces enable more efficient optical path control compared to traditional spherical lenses, allowing compact design while maintaining high imaging performance
Solution Approach 2:
The patent optimizes specific parameter relationships within the lens group, including the back focus to focal length ratio (0.1 < BF/f < 0.5) and the shape of the final surface (tilting toward object side), to achieve compact dimensions while correcting optical aberrations and maintaining high imaging quality
2Manufacturing precision
If a gull shape final surface is used to curb off-axis aberration and chief ray angle, then aberration correction is improved, but ghost light is concentrated on the imaging surface causing image quality deterioration
Solution Approach 1:
The patent modifies the final surface shape to tilt toward the object side, which transforms the problematic ghost light reflection pattern into a diverging pattern. This design converts the potential harm of surface reflections into a beneficial effect where ghost light is dispersed away from the imaging surface rather than concentrated, while still maintaining effective aberration correction
Solution Approach 2:
The patent specifies particular parameter ranges for the final surface geometry, including the tilting angle toward the object side and the relationship between back focus and focal length (0.1 < BF/f < 0.5), to optimize the balance between aberration correction capability and ghost light suppression
3Manufacturing precision
If the imaging surface is curved to improve aberration correction and lens performance, then imaging quality is improved, but reflection between the final surface and curved imaging surface creates converging ghost light
Solution Approach 1:
The patent addresses the converging ghost light issue by designing the final surface to tilt toward the object side, which converts the converging reflection pattern into a diverging pattern. This modification maintains the benefits of the curved imaging surface for aberration correction while eliminating the harmful concentration of ghost light on the imaging surface
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 effectively reduces ghost light intensity, improving image quality by ensuring appropriate aberration correction and maintaining a compact lens design.
Implementation Method 1
a lens group including six or more lenses including at least one aspherical lens that forms an optical image of an object on an imaging surface
Implementation Method 2
ghost light caused by reflection between a final surface of the imaging lens and a curved imaging surface
Data Source
AI summary
To curb deterioration in image quality due to ghost light caused by reflection. An imaging lens includes a lens group with at least one aspherical lens that forms an optical image of an object on an imaging surface curved concavely toward an object side. The lens surface closest to an imaging surface side in the lens group, is aspherical, and a sign of surface power is not inverted with increasing distance from an optical axis. The final surface tilts toward an object side with increasing distance from the optical axis. The imaging lens satisfies 0.1<BF/f<0.3 when a distance on the optical axis from a vertex on the optical axis of the final surface to a position of a maximum image height of the imaging surface is denoted by BF, and a focal length of the entire imaging lens is denoted by f.