Four-Lens Imaging Optical System for Miniaturization and High Resolution
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Solution Overview
Problem
Existing imaging optical systems face challenges in achieving high resolution and miniaturization while maintaining optical performance, particularly for camera modules with 5 or more-megapixel image sensors, as they require a balance between lens count and refractive power that is difficult to achieve with conventional lens configurations.
Innovation Solution
A compact imaging optical system using four plastic lenses with specific refractive power distributions and aspherical surfaces, including a first lens with positive refractive power, a second lens with negative refractive power, a third lens with a meniscus shape, and a fourth lens with a concave object-side surface, along with an aperture stop, to optimize field curvature and reduce distortion and spherical aberration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If three or less sheets of lenses are used, then miniaturization is achieved, but high resolution and optical capabilities cannot be satisfied for 5 or more-megapixel image sensors
Solution Approach 1:
The patent applies aspherical surface parameters to the lens design, changing the geometric parameters from traditional spherical surfaces to aspherical surfaces. This allows each lens element to provide more optical power while correcting aberrations, enabling high-resolution imaging with fewer lens elements and reduced overall system size suitable for 5MP+ sensors
Solution Approach 2:
The patent uses plastic lens materials with specific refractive indices and Abbe numbers, combining multiple plastic lens elements with different optical properties. This composite approach allows optimization of each element's contribution to resolution and aberration control while maintaining compact dimensions
2Manufacturing precision
If four or more sheets of lenses are used, then high resolution is achieved, but total length of the optical system increases and miniaturization is not ensured
Solution Approach 1:
The aspherical surface parameters enable each lens element to achieve higher optical power density. The specific aspherical coefficients allow the lenses to provide increased refractive capability within shorter axial distances, maintaining high resolution while reducing the total optical system length for miniaturization
Solution Approach 2:
The patent transitions from traditional spherical lens geometry to aspherical geometry, effectively utilizing additional geometric dimensions in the lens surface definition. This allows light rays to be controlled more efficiently through the lens, achieving high resolution imaging with reduced axial length
3Ease of manufacture
If lenses are formed of spherical lenses, then manufacturing is simpler, but total length of the optical system increases and miniaturization is not ensured
Solution Approach 1:
The patent specifies aspherical surface parameters with defined coefficients for each lens element. These parameterized aspherical surfaces can be manufactured using precision molding techniques for plastic lenses, achieving miniaturization while maintaining manufacturability through standardized aspherical surface definitions and modern manufacturing capabilities
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 system achieves high resolution and miniaturization with improved optical performance, suitable for 5 or more-megapixel camera modules, while being cost-effective for mass production due to the use of plastic lenses and simplified manufacturing processes.
Implementation Method 1
a first lens having positive refractive power and two convex surfaces
Implementation Method 2
a second lens having negative refractive power and two concave surfaces
Implementation Method 3
a third lens having positive refractive power and a meniscus shape
Implementation Method 4
a fourth lens having a concave object-side surface
Data Source
AI summary
There is provided an imaging optical system installed in a mobile communications terminal and a personal digital assistant (PDA) or utilized in a surveillance camera and a digital camera. The imaging optical system including, sequentially from an object side in front of an image plane: a first lens having positive refractive power and two convex surfaces; a second lens having negative refractive power and two concave surfaces; a third lens having positive refractive power and a meniscus shape; and a fourth lens having a concave object-side surface. The fourth lens has a shape satisfying following condition 1:10<|R8/F|<50 condition 1,where R8 is a radius of curvature of the object-side surface of the fourth lens, and F is an overall focal length of the imaging optical system.