Folded Tele Camera with Floating Lens Group and SMA Actuator
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Solution Overview
Problem
Dual-aperture zoom cameras face challenges in miniaturization, particularly with bulky and noisy actuators, high F-numbers, and large lens assembly heights, which hinder the integration of macro-photography capabilities in compact devices without additional hardware.
Innovation Solution
The design incorporates a folded camera structure with a lens comprising three movable lens element groups (G1, G2, and G3) where G1 and G3 are fixedly attached, allowing G2 to float between stops, utilizing a shape memory alloy actuator and voice coil motor mechanism for precise movement, enabling efficient zoom and focus adjustments while maintaining a compact form factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional actuators (stepper motors or piezoelectric actuators) are used for lens element movement, then zoom and focus functions can be achieved, but the actuators become bulky, noisy, and unreliable
Solution Approach 1:
The patent replaces traditional mechanical actuators (stepper motors, piezoelectric actuators) with a voice coil motor system that uses electromagnetic fields to move lens elements. This substitution eliminates the need for complex mechanical transmission components like screws and gears, resulting in a more reliable, compact, and quieter actuation system while maintaining precise control over lens element positions for zoom and focus functions
Solution Approach 2:
The patent changes the actuation mechanism from mechanical (contact-based) to electromagnetic (field-based), fundamentally altering the physical principle used for movement. This parameter change enables smoother, quieter operation with higher reliability while reducing the overall size of the actuator assembly, directly resolving the contradiction between reliability and device complexity
2Adaptability or versatility
If a folded camera structure with multiple lens element groups is used, then zoom capability is improved, but the camera height increases
Solution Approach 1:
The patent employs a folded optical path design where the light path is bent at approximately 90 degrees using a reflecting element, allowing the optical axis to change direction. This dimensional change enables the camera to achieve a long effective focal length for zoom functionality while maintaining a compact physical height, as the light travels through a folded path rather than a straight line extending the camera length
Solution Approach 2:
The patent arranges lens element groups G1, G2, and G3 in a nested configuration along the folded optical path, with each group positioned to work in conjunction with the others. The reflecting element folds the optical path back on itself, creating a compact nested structure that achieves high zoom capability (e.g., 5x zoom) while keeping the overall camera height minimal, effectively nesting the optical components within a small volume
3Illumination intensity
If the F-number is reduced for better light gathering, then image quality improves, but the lens assembly height increases
Solution Approach 1:
The folded optical path design allows the lens assembly to achieve a low F-number (e.g., F/2.8 or lower) by providing a long effective aperture diameter relative to the focal length, while the folded configuration keeps the physical height of the lens assembly compact. The reflecting element enables the light path to fold back, maintaining a large aperture opening without increasing the camera height proportionally
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 achieves a significant reduction in camera height, improves actuator reliability, and enables macro-photography capabilities without additional hardware, enhancing the zooming effect and image quality in compact devices.
Implementation Method 1
utilizing a shape memory alloy actuator and voice coil motor mechanism for precise movement
Implementation Method 2
utilizing a shape memory alloy actuator and voice coil motor mechanism for precise movement
Implementation Method 3
a reflecting element (also referred to as optical path folding element or OPFE) that folds light arriving from an object or scene along a first optical path to a second optical path toward the Tele image sensor
Data Source
AI summary
Multi-cameras and in particular dual-cameras comprising a Wide camera comprising a Wide lens and a Wide image sensor, the Wide lens having a Wide effective focal length EFLW and a folded or non-folded Tele camera comprising a Tele lens with a first optical axis, a Tele image sensor and an OPFE, wherein the Tele lens includes, from an object side to an image side, a first lens element group G1, a second lens element group G2 and a third lens element group G3, wherein at least two of the lens element groups are movable relative to the image sensor along the first optical axis to bring the Tele lens to a Macro state or to two zoom states, wherein an effective focal length (EFL) of the Tele lens is changed from EFLT,min in one zoom state to EFLT,max in the other zoom state, wherein EFLTmin>1.5×EFLW and wherein EFLTmax>1.5×EFLTmin. In the Macro state, the lens with EFLT,min allows for focusing on objects with short object-camera distances such as 5 cm. Actuators for enabling the movements are also disclosed.