Prism-Folded Optical Imaging for Compact Telephoto Camera Modules
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Solution Overview
Problem
The increasing demand for telephoto lenses with long focal lengths in camera modules is hindered by the need for a sufficient back focal length, which inevitably increases the size of the camera module, making it disadvantageous for portable terminals.
Innovation Solution
An optical imaging system comprising a first lens, a second lens, a third lens, and a reflective member, such as a parallelogram-shaped prism, configured to change the light path twice, with specific refractive powers and materials like plastic and glass, and adhering to certain optical parameters to maintain compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a telephoto lens with long focal length is used, then optical performance is improved, but the size of the camera module increases
Solution Approach 1:
The patent introduces a reflective member (prism) to fold the optical path, changing the light propagation from a straight line to a multi-directional path. This dimensional change allows the optical system to achieve a long effective focal length while maintaining a compact physical footprint, resolving the contradiction between optical performance and module size
Solution Approach 2:
The reflective member is positioned within the optical path between the lens assembly and image sensor, nesting the reflection function within the existing optical structure. This allows the system to achieve telephoto functionality without adding significant external volume to the camera module
2Measurement precision
If back focal length is increased to accommodate telephoto lens, then optical performance is improved, but the length of the camera module increases
Solution Approach 1:
The reflective member folds the optical path at multiple angles, transforming the linear relationship between back focal length and module length. By redirecting light through multiple reflections, the system achieves sufficient back focal length for telephoto operation while keeping the physical length of the camera module compact
3Volume of moving object
If a reflective member with multiple reflective surfaces is used, then light path is changed twice to achieve compact design, but device complexity increases
Solution Approach 1:
The patent combines multiple reflective surfaces into a single integrated prism component rather than using separate mirrors or reflectors. This merging approach achieves the desired light path folding while reducing the number of discrete components, assembly steps, and alignment requirements, thereby limiting the increase in device complexity
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 a compact design while maintaining optical performance by optimizing lens configurations and using a reflective member to alter the light path, addressing the size constraint of telephoto lenses in portable terminals.
Implementation Method 1
The reflective member includes at least two reflective surfaces configured to change a path of light passing through the first to third lenses and incident on the reflective member at least twice
Implementation Method 2
The first lens may have positive refractive power, the second lens have negative refractive power, and the third lens may have positive refractive power or negative refractive power
Data Source
AI summary
An optical imaging system includes a first lens, a second lens, a third lens, a reflective member, and an image sensor sequentially arranged from an object side. The reflective member includes at least two reflective surfaces to change a path of light passing through the first to third lenses and incident on the reflective member at least twice.