Four-Lens Camera Assembly for Rangefinder Aperture and Size Trade-off
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Solution Overview
Problem
Current camera lens assemblies for rangefinder cameras face challenges in achieving a balance between large aperture, miniaturization, and high image quality, with traditional miniaturized lens assemblies having small apertures and being unsuitable for rangefinder cameras.
Innovation Solution
A camera lens assembly comprising four lenses, with specific refractive powers and surface types, is designed to achieve a large aperture and miniaturization while maintaining high image quality. The assembly includes a first lens with a positive refractive power and a concave image-side surface, a fourth lens with a positive refractive power and a convex object-side surface, and a band-pass filter between the fourth lens and the image side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a traditional miniaturized lens assembly is used, then the size is reduced, but the aperture becomes small and cannot satisfy rangefinder camera requirements
Solution Approach 1:
The lens assembly is divided into four separate lenses (first lens, second lens, third lens, and fourth lens) with specific refractive power distributions. This segmentation allows each lens to contribute to specific optical functions, enabling the system to achieve both compact size and large aperture by optimizing the individual characteristics and arrangements of each lens element.
Solution Approach 2:
The patent specifies precise parameter ranges including refractive powers of the four lenses, the ratio of the second lens thickness to total thickness (0.03≤CT2/ΣCT≤0.15), and the f-number range (f/EPD≤2). By optimizing these parameters, the lens assembly achieves miniaturization while maintaining a large effective aperture, resolving the contradiction between size reduction and aperture maintenance.
2Area of stationary object
If the aperture is enlarged to satisfy rangefinder camera requirements, then light gathering capability improves, but the lens assembly size increases
Solution Approach 1:
By segmenting the optical system into four lenses with specific refractive power distributions, the patent achieves large aperture (f/EPD≤2) while maintaining compact size. The segmented structure allows optimized light path management and aberration correction that enables high performance in a miniaturized format.
Solution Approach 2:
The patent utilizes complex spatial arrangement of the four lenses along the optical axis with specific spacing relationships. This multi-dimensional optimization of lens positioning and orientation enables the system to achieve both large aperture and miniaturization by efficiently utilizing three-dimensional space rather than relying on single-dimensional expansion.
3Manufacturing precision
If a four-lens assembly with specific refractive powers is used, then aberrations are corrected and image quality improves, but the device complexity increases
Solution Approach 1:
Each lens is assigned specific local optical characteristics: the first lens has positive refractive power with a concave image-side surface, the fourth lens has positive refractive power with a convex object-side surface, and the second and third lenses have specific refractive power distributions. This local optimization of quality parameters enables effective aberration correction while maintaining manageable structural complexity through systematic design.
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
The solution effectively enlarges the aperture, shortens the total length of the lens assembly, ensures miniaturization, corrects various aberrations, and improves image quality, making it suitable for laser rangefinder cameras.
Implementation Method 1
The first lens and the fourth lens both have positive refractive powers, an image-side surface of the first lens is a concave surface, and an object-side surface of the fourth lens is a convex surface
Implementation Method 2
a filter is disposed between the fourth lens and the image side, the filter may be a band-pass filter, a band-pass wavelength λ of the band-pass filter fluctuates based on a wavelength of a used light source
Data Source
AI summary
The present disclosure discloses a camera lens assembly, the camera lens assembly having a total effective focal length f and an entrance pupil diameter EPD, and along an optical axis from an object side to an image side sequentially including a first lens, a second lens, a third lens and a fourth lens, wherein the first lens and the fourth lens have positive refractive powers, an image-side surface of the first lens is a concave surface, and an object-side surface of the fourth lens is a convex surface. In addition, the total effective focal length f and the entrance pupil diameter EPD satisfy: f/EPD≤2.