Folded Camera Lens Layout for Low f/# in Slim Modules
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Solution Overview
Problem
Existing smartphone cameras face challenges in achieving low f/# for improved low light sensitivity, Bokeh effect, and image resolution due to complex lens designs that correct for large apertures, leading to increased total track length and camera module height, which is detrimental to slim smartphone design.
Innovation Solution
A folded camera design with N≥7 lens elements and an optical path folding element (OPFE) that provides a folded optical path, with an aperture stop closer to the first lens element and an f/# smaller than 1.2, allowing for a compact design with improved optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a complex lens design is used to correct for large apertures, then low light sensitivity and Bokeh effect are improved, but total track length and camera module height increase
Solution Approach 1:
The patent applies optical path folding using a prism to change the spatial dimension of light propagation. The folded optical path allows the light to travel a longer effective distance through the lens elements while occupying a more compact physical volume, thereby reducing the camera module height while maintaining the benefits of a complex lens design for low light performance
2Shape
If a complex lens design is used to correct for large apertures, then Bokeh effect is improved, but camera module height increases
Solution Approach 1:
The optical path folding technique reconfigures the spatial arrangement of light rays through the lens system. By introducing a folding prism at a specific angle, the patent enables the light to traverse the lens elements in a folded pattern, achieving the desired Bokeh effect with a more compact overall height
3Illumination intensity
If aperture stop is positioned closer to the first lens element, then f-number is reduced, but optical path complexity increases
Solution Approach 1:
The patent introduces an optical path folding element (prism) as an intermediary component that mediates between the aperture stop and the lens elements. This intermediary enables the aperture stop to be positioned closer to the first lens element for a lower f-number while managing the resulting optical path complexity through the folding geometry
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 folded camera design achieves a low f/#, enhancing low light sensitivity, Bokeh effect, and image resolution while maintaining a slim form factor by reducing the total track length and camera module height.
Implementation Method 1
an OPFE for providing a folded optical path between an object and the lens, to the lens optical axis
Implementation Method 2
a lens with N≥7 lens elements Li, having an effective focal length (EFL)
Data Source
AI summary
Folded cameras with a total track length (TTL), f numbers smaller than 1.2 and large fields of view, e.g. of at least 60 degrees. Such folded cameras may comprise a lens with N≥7 lens elements, an image sensor and an optical path folding element for providing a folded optical path between an object and the lens, wherein an aperture stop of the lens is located closer to a first surface of the first lens element facing the object than a distance d that fulfills d/TTL=0.2.