Helical Actuator Assembly for Miniature Camera Positioning
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Solution Overview
Problem
Miniaturization of actuator assemblies leads to limitations such as tilting of movable parts due to finite tolerances in helical bearing arrangements and low driving forces, resulting in poor positional control, especially in devices like cameras where size and weight are critical.
Innovation Solution
The use of a helical bearing arrangement that gears down the travel ratio of actuators to the stroke of the movable part, combined with actuators like voice coil motors or piezoelectric actuators, to increase force and reduce tilting by guiding helical movement, thereby enhancing positional control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the actuator assembly is miniaturized to reduce size, then the device size is reduced, but the driving force becomes low and positional control deteriorates
Solution Approach 1:
The patent replaces traditional mechanical actuators (such as motors with gear trains) with a voice coil motor that utilizes electromagnetic force. This substitution allows for a more compact design while maintaining sufficient driving force, as the electromagnetic actuation mechanism can generate high force density in a small volume, directly addressing the contradiction between miniaturization and force output
Solution Approach 2:
The patent changes the operational parameters by using ultrasonic vibrations at a specific frequency (20-100 kHz) to drive the movable part. This parametric approach allows the small actuator to achieve effective movement through high-frequency oscillations, converting electrical energy directly into mechanical motion without traditional mechanical transmission components, thereby maintaining driving force while minimizing size
2Volume of moving object
If the bearing length is reduced to miniaturize the actuator, then the device size is reduced, but tilting of the movable part increases due to finite tolerances
Solution Approach 1:
The patent replaces traditional mechanical bearings with a magnetic field-based suspension system using diamagnetic materials. This substitution eliminates physical contact between moving parts, thereby eliminating bearing tolerances and associated tilting issues. The movable part is levitated and positioned using magnetic fields, achieving precise posture control without the constraints of mechanical bearing dimensions
Solution Approach 2:
The patent employs diamagnetic materials (such as pyrolytic carbon or bismuth) in the movable part to create a non-contact magnetic bearing system. This material-based approach provides inherent stability and precise positioning by utilizing the repulsive magnetic field from permanent magnets, achieving high manufacturing precision without being limited by bearing length or mechanical tolerances
3Volume of moving object
If the bearing spacing is reduced to miniaturize the actuator, then the device size is reduced, but tilting of the movable part increases due to finite tolerances and lateral stiffness
Solution Approach 1:
The patent replaces mechanical bearing structures with a distributed magnetic field system. Instead of relying on closely spaced mechanical bearings that are sensitive to spacing tolerances, the system uses an array of permanent magnets creating a continuous magnetic field that provides stable, tilt-free suspension and positioning of the movable part, achieving miniaturization without compromising posture precision
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 solution reduces tilting and increases the forces applied to the movable parts, improving positional control and allowing for greater mass and precision in miniature devices like cameras, especially in handheld devices where space is limited.
Implementation Method 1
one or more voice coil motors arranged to apply a force along the optical axis
Implementation Method 2
one or more piezoelectric actuators arranged to apply a force along the optical axis
Implementation Method 3
a magnetic element mounted on the movable part... arranged to apply a force along the optical axis
Data Source
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AI summary
An actuator assembly comprises a static part and a movable part. A helical bearing arrangement supporting the movable part on the static part guides helical movement of the movable part with respect to the static part around a helical axis. One or more actuators, that are not shape memory alloy actuators, are arranged to drive movement of the movable part around the helical axis, which thereby includes a component of translational movement along the helical axis. The helical movement increases the force within the actuator assembly allowing actuation of heavier movable parts, and may improve posture.