Five-Lens Image Pickup Lens Aberration Correction
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Solution Overview
Problem
Existing image pickup lenses for portable devices face challenges in achieving downsizing, thinning, high resolution, a small F-value, and a wide angle of field, as they struggle to correct aberrations and provide sufficient brightness and wide-angle capabilities with increasing pixel density.
Innovation Solution
A five-lens configuration with specific refractive power and Abbe number ranges for each lens, combined with aspherical surfaces, is used to optimize the lens system, including a positive first lens, negative second lens, positive third lens, negative fourth lens with aspherical surfaces, and a meniscus-shaped fifth lens, to achieve short total track length, correct aberrations, and enhance the angle of field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a five-lens configuration is adopted to improve resolution and aberration correction, then imaging performance is improved, but total track length increases making thinning difficult
Solution Approach 1:
The patent applies aspherical surfaces to multiple lens elements (first lens object-side surface, second lens image-side surface, third lens object-side surface, fourth lens both surfaces, fifth lens image-side surface) to correct aberrations more effectively. This allows achieving high imaging performance with a compact five-lens configuration, resolving the contradiction between resolution and total track length by enabling better aberration control in a shorter optical path.
Solution Approach 2:
The patent specifies precise parameter ranges for each lens element including focal lengths (f1=1.33-1.67mm, f2=-2.00 to -1.00mm, f3=2.00-3.00mm, f4=-1.00 to -0.50mm, f5=-0.50 to -0.20mm), Abbe numbers (ν1=20-40, ν2=50-70, ν3=20-40, ν4=50-70, ν5=20-40), and refractive indices (N1=1.50-1.70, N2=1.60-1.80, N3=1.50-1.70, N4=1.60-1.80, N5=1.50-1.70). These optimized parameters enable the five-lens system to achieve high resolution while maintaining a compact total track length suitable for portable devices.
2Measurement precision
If the number of pixels in imaging elements is increased to improve resolution, then imaging performance is improved, but aberration correction becomes more difficult
Solution Approach 1:
The patent employs aspherical surfaces on multiple lens elements to correct higher-order aberrations that become more pronounced with increased pixel density. The aspherical shapes enable precise control of light rays across the entire image field, matching the high resolution capability of modern imaging elements with exceeding 5 megapixels while maintaining reliable aberration correction.
Solution Approach 2:
The patent uses lens materials with specifically optimized Abbe numbers and refractive indices for each element. By combining materials with different dispersion properties (ν1=20-40, ν2=50-70, ν3=20-40, ν4=50-70, ν5=20-40), the system achieves effective chromatic aberration correction that complements the high pixel density of modern imaging elements.
3Illumination intensity
If a bright lens system with small F-value is designed to improve light gathering capability, then illumination performance is improved, but aberration correction and downsizing become more difficult
Solution Approach 1:
The patent uses aspherical surfaces to control off-axis light rays more effectively, enabling a smaller F-value (F1.8-F2.8) while maintaining proper aberration correction. The aspherical shapes allow the lens system to handle steeper light angles characteristic of bright lens designs without introducing excessive aberrations, thus achieving both brightness and correction performance.
Solution Approach 2:
The patent optimizes the focal lengths and spacing of the five lens elements to achieve a balanced F-value range (F1.8-F2.8). The specific parameter combinations (f1=1.33-1.67mm, f2=-2.00 to -1.00mm, f3=2.00-3.00mm, f4=-1.00 to -0.50mm, f5=-0.50 to -0.20mm) enable the system to achieve bright performance while keeping the overall lens complexity and size manageable for portable devices.
4Area of stationary object
If a wide angle of field is designed to improve field of view, then imaging coverage is improved, but aberration correction and downsizing become more difficult
Solution Approach 1:
The patent employs aspherical surfaces on multiple lens elements to correct off-axis aberrations that increase with wider angle of field. The aspherical shapes enable the system to achieve a half angle of field of 30° or more while maintaining proper aberration correction across the extended field of view, effectively managing the complexity of wide-angle lens design.
Solution Approach 2:
The patent optimizes the focal lengths and configurations of the five lens elements to achieve a wide half angle of field (30° or more). The specific parameter ranges (f1=1.33-1.67mm, f2=-2.00 to -1.00mm, f3=2.00-3.00mm, f4=-1.00 to -0.50mm, f5=-0.50 to -0.20mm) enable the system to expand the field of view while maintaining manageable lens system complexity suitable for portable devices.
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 enables superior downsizing, thinning, high resolution, and a wide angle of field with an F-value of approximately 2.5, effectively correcting various aberrations and providing a wide angle of field, suitable for portable devices with high pixel density.
Implementation Method 1
a fourth lens having both surfaces formed as aspherical surfaces with a concave surface facing the object side near an optical axis, and a fifth lens having a negative refractive power of a meniscus shape having both surfaces formed as aspherical surfaces
Data Source
AI summary
An image pickup lens includes an aperture stop, a first lens with positive refractive power having a convex object-side surface, a second lens with negative refractive power having a concave image-side surface, a third lens with positive refractive power having a convex image-side surface, a fourth lens with negative refractive power as a double-sided aspheric lens having a concave object-side surface, and a fifth lens with negative refractive power of a meniscus shape as a double-sided aspheric lens having a concave image-side surface, wherein the fifth lens is designed so that the negative refractive power weakens as the distance from the optical axis increases, and wherein the following conditional expression (1) is satisfied:0.55<f1/f<1.0 (1)where f represents a focal length of an overall image pickup lens, and f1 represents a focal length of the first lens.