Telephoto Lens System with Internal Refractor for Compact Height
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Solution Overview
Problem
Conventional telephoto lens systems with long focal lengths face challenges in miniaturization for use in thin devices like smartphones, as they require a long total track length, leading to increased depth and reduced lens aperture, which compromises resolution due to diffraction when attempting to reduce size.
Innovation Solution
A telephoto lens system with a refractor between the second and third lenses to bend the optical axis, comprising five lenses with balanced positive and negative refractive powers, and aspherical plastic lenses, minimizing height while maintaining high resolution and correcting distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a reflector is added in front of the lens to bend the optical axis, then the optical path is folded to reduce overall lens length, but depth is increased due to the length of the prism, causing F-number to increase and lens aperture to be reduced
Solution Approach 1:
The patent places the reflector between the second and third lenses rather than in front of the first lens, utilizing the internal space along the optical path to fold the optical axis. This dimensional repositioning allows the optical path to be folded without increasing the overall lens length or reducing the lens aperture, as the reflector is positioned where it can bend light without obstructing the entrance pupil or increasing the front depth of the lens assembly.
2Length of moving object
If the lens system size is reduced to fit thin devices, then the total track length is shortened, but resolution is reduced due to diffraction from reduced aperture
Solution Approach 1:
By folding the optical axis using a reflector positioned between the second and third lenses, the patent achieves a compact total track length suitable for thin devices while maintaining the full lens aperture. The optical path is bent within the existing lens structure, allowing the light to travel a longer effective path without increasing the physical length of the lens assembly, thereby avoiding diffraction-induced resolution loss.
3Length of moving object
If a reflector is added to bend the optical axis, then the optical path is folded, but the structure becomes more complex and the height of the lens system increases
Solution Approach 1:
The patent integrates the reflector into the existing lens structure by positioning it between the second and third lenses, merging the optical folding function with the existing multi-element lens design. This integration allows the reflector to be part of the compact lens assembly rather than an external add-on, reducing overall structural complexity while achieving the desired optical path folding.
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 reduces the height of the lens system, allowing it to be applied to small camera modules like smartphones, while maintaining a long effective focal length and high resolution with corrected distortion and low F-number.
Implementation Method 1
a refractor bending an optical axis is provided between the second lens and the third lens
Implementation Method 2
a first lens having a positive refractive power; a second lens having a negative refractive power; a third lens having a negative refractive power; a fourth lens having a negative refractive power; and a fifth lens having a positive refractive power
Data Source
AI summary
A telephoto lens system having a plurality of lenses toward a focal object is proposed. The system includes a first lens with a positive refractive power, a second lens with a negative refractive power, a third lens with a negative refractive power, a fourth lens with a negative refractive power, and a fifth lens with a positive refractive power. A refractor bending an optical axis is provided between the second lens and the third lens. The angle (A) between the optical axes of the second lens and the third lens satisfies 80°≤A≤86°. A barrel surrounding the first lens is provided by protruding more toward the focal object than the first lens. The inner diameter of the barrel is smaller than or equal to the effective diameter of the first lens, and a stop is arranged toward the focal object of the first lens.