Compact Camera Optical System Using Aspheric Plastic Lenses
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Solution Overview
Problem
The existing optical systems in mobile communication devices face challenges in reducing size and cost while maintaining high optical performance, as they often use plastic lenses that deteriorate in performance compared to glass lenses and require multiple lenses, leading to increased size and aberrations when the aperture stop is positioned at the forefront.
Innovation Solution
An optical system configuration with four aspheric plastic lenses, where the aperture stop is placed between the first and second lenses, and the lens most adjacent to the object has a concave surface, reducing the size of the first lens and improving aberration characteristics, with specific refractive indices and Abbe numbers for each lens to correct color aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass lenses are used to maintain high optical performance, then optical transmittance and refractive index are improved, but size and manufacturing cost increase
Solution Approach 1:
The patent changes the material parameter from glass to plastic lenses, and modifies the lens surface geometry from spherical to aspheric. This allows plastic lenses to achieve optical performance comparable to glass while reducing size and cost. The aspheric surfaces enable better aberration correction with fewer lenses
Solution Approach 2:
The optical system is divided into four distinct lens elements with specific positive and negative refractive powers. This segmentation allows each lens to be optimized for specific optical functions, achieving high performance with a compact arrangement that would not be possible with a single lens or fewer elements
2Volume of moving object
If the number of lenses is reduced to decrease size and cost, then manufacturing cost and size are improved, but optical performance deteriorates
Solution Approach 1:
The patent employs aspheric surface parameters for all four lenses, which enables each lens to correct multiple types of aberrations simultaneously. This parameter optimization allows the system to achieve high optical performance with only four lenses, proving that strategic parameter changes can compensate for reduced lens count
Solution Approach 2:
The patent uses plastic material for all lenses instead of traditional glass, creating a composite optical system that combines multiple plastic lenses with different refractive indices and Abbe numbers. This material selection enables cost-effective manufacturing while maintaining optical performance through proper material composition and arrangement
3Ease of manufacture
If aperture stop is positioned at the forefront to follow general design, then ease of manufacture is improved, but aberrations increase and optical performance deteriorates
Solution Approach 1:
The patent inverts the conventional aperture stop positioning by placing it between the first and second lenses rather than at the very front. This reversal of the standard design approach eliminates the aberrations caused by light passing through the aperture stop at an angle, while the first lens with positive refractive power still effectively controls the overall light path
4Ease of manufacture
If aperture stop is positioned away from the first lens to follow general design, then ease of manufacture is improved, but the size of the first lens and optical system length increase
Solution Approach 1:
The patent reverses the conventional aperture stop placement strategy by positioning it close to the first lens rather than away from it. This inverted approach allows the first lens to maintain a compact size while still performing its optical function, and prevents the optical system length from increasing as would occur with traditional aperture positioning
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 results in a compact optical system with improved design flexibility, reduced size, and enhanced aberration characteristics, including astigmatism and distortion, while maintaining high resolution and correcting color aberrations, suitable for mobile communication terminals.
Implementation Method 1
all lenses constituting the optical system are configured by aspheric plastic lenses
Implementation Method 2
a first lens that has a positive refractive index and has a convex shape toward an object; a second lens that has a negative refractive index and has a concave shape at both surfaces
Data Source
AI summary
The present invention relates to an optical system for a camera.The optical system for a camera in accordance with the present invention includes: a first lens that has a positive refractive index and has a convex shape toward an object; a second lens that has a negative refractive index and has a concave shape at both surfaces; a third lens that has the positive refractive index and has the convex shape upwards; and a fourth lens that has the negative refractive index and has a concave surface on an object-side surface, and has at least one inflection point on an image surface. It is possible to implement a compact optical system for a camera which can be applied to a mobile communication terminal by improving design flexibility.