Folded Macro-Tele Lens Layout for Smartphone Close-Up Bokeh
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Solution Overview
Problem
Existing smartphone cameras struggle with capturing high-quality macro images from short object-lens distances due to limited magnification, large depth of field, and poor optical Bokeh, especially when focusing on objects close to the camera.
Innovation Solution
A folded digital camera design with a lens system comprising N≥6 lens elements, an optical path folding element, and an image sensor, featuring a focusing range from infinity to a minimal object distance with optimized optical properties such as EFL, TTL, and Max CRA/FOV ratios, allowing for high magnification and controlled depth of field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional lens system is used in smartphone cameras, then the device maintains a compact form factor, but the magnification capability at short object-lens distances is limited and optical Bokeh quality is poor
Solution Approach 1:
The lens system is divided into multiple lens elements (N≥6) with different optical properties, including at least one aspherical lens element. This segmentation allows each element to contribute specifically to magnification capability while managing overall system complexity through specialized functions for each element.
Solution Approach 2:
The patent incorporates at least one aspherical lens element with non-spherical surfaces. This asymmetry in the lens element geometry enables improved magnification control and optical Bokeh quality at short object-lens distances, resolving the contradiction between measurement precision and device complexity.
2Measurement precision
If the lens system is designed for high magnification at short distances, then macro imaging capability is improved, but the depth of field becomes uncontrollably large
Solution Approach 1:
The lens system employs at least one aspherical lens element with locally varied surface curvature. This local quality variation allows precise control over light ray paths, enabling high magnification while maintaining controllable depth of field by adjusting the curvature distribution in specific regions of the lens element.
Solution Approach 2:
The patent utilizes aspherical surfaces defined by mathematical parameters (conic constant k and higher-order coefficients A4, A6, A8, A10) to control optical properties. By adjusting these parameters, the system achieves high magnification capability while maintaining reliable depth of field control through precise parameter optimization.
3Measurement precision
If more lens elements are added to improve optical performance, then magnification and Bokeh quality improve, but the lens barrel size and device complexity increase
Solution Approach 1:
The patent incorporates a focus adjustment mechanism that moves at least one lens element (specifically the aspherical element) along the optical axis. This dynamic adjustment capability allows the system to achieve high magnification and optimal Bokeh quality without requiring a permanently larger lens barrel, as the elements can be repositioned to optimize performance for different shooting scenarios.
Solution Approach 2:
The lens elements are arranged in a compact configuration where multiple elements are nested within the lens barrel structure. The aspherical lens element is positioned strategically among other elements, allowing efficient space utilization and minimizing the overall lens barrel volume while maintaining the required number of elements for high optical performance.
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 design enables capturing macro images with larger object-to-image magnification (1:1-15:1) and high optical Bokeh, while maintaining a compact form factor suitable for smartphones.
Implementation Method 1
OPFE folds the optical path from a first optical path 112 to a second optical path 114
Implementation Method 2
a lens 104 with a plurality of lens elements... The path of the optical rays from an object (not shown) to image sensor 106 defines an optical path
Data Source
AI summary
Folded digital cameras comprising a lens system with a lens and an image sensor, the lens having N≥6 lens elements Li, an effective focal length (EFL) and a total track length (TTL), wherein each lens element has a respective focal length fi and wherein a first lens element L1 faces an object side, and an optical path folding element (OPFE) for providing a folded optical path between an object and the lens. In some embodiments, the lens system has a focusing range that covers object-lens distances from infinity to a minimal object distance (MIOD), wherein MIOD/EFL is smaller than 20 or even 7. In some embodiments, the ratio of a maximal chief ray angle to a field of view of the folded camera Max CRA/FOV is smaller than 0.25 or even 0.15 when the camera is focused at infinity.