Ball-Guided Voice Coil Actuator for Compact Folded Optics
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Solution Overview
Problem
There is a need for a linear ball-guided voice coil motor (VCM) actuator that can reduce the dimensions of folded cameras, particularly the height and width, while also providing actuation mechanisms for optical path folding elements (OPFEs) in digital cameras, which is not efficiently addressed by existing spring-guided or ball-guided rail technologies.
Innovation Solution
The implementation of a linear ball-guided VCM actuator with two VCM engines and corresponding rails, allowing movement in perpendicular directions for focus and optical image stabilization, integrated with a middle moving frame and static base, utilizing ferromagnetic yokes and Hall bar position sensors for precise control, to enable compact and efficient actuation within folded camera structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a spring-guided rail is used to guide lens movement, then the mechanical guidance is simple, but the power consumption increases because the magnetic force must oppose the spring mechanical force
Solution Approach 1:
The patent removes the spring element from the guidance system, extracting the mechanical force opposition that caused high power consumption. The ball-guided rail system operates without springs, allowing the voice coil motor to move the lens group without constantly opposing spring force, thereby reducing power consumption while maintaining guidance functionality through the ball-rail mechanism.
2Adaptability or versatility
If a ball-guided rail is used to guide lens movement, then the power consumption decreases and reliability in drops increases, but the device cannot be adapted to folded camera structures
Solution Approach 1:
The patent adapts the ball-guided rail system to folded camera structures by introducing a prism that redirects the optical path at a 45-degree angle. This dimensional change in the optical path allows the lens assembly to be positioned and moved in a configuration suitable for folded cameras, where the optical axis is folded back onto itself, while maintaining the benefits of the ball-guided rail system.
3Volume of moving object
If the camera module is folded to reduce dimensions, then the camera height and width are reduced, but the optical path requires folding elements that need actuation mechanisms
Solution Approach 1:
The patent merges the actuation of the lens assembly and the optical path folding element (prism) into a single integrated system. Both elements are actuated by voice coil motors mounted on a common moving frame, allowing coordinated movement to achieve both focus adjustment and optical path folding in a unified mechanism, thereby reducing overall system complexity despite the folded configuration.
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 allows for reduced camera dimensions while providing effective autofocus and optical image stabilization, with lower power consumption and higher reliability, by enabling precise and controlled movement of optical elements within the camera's compact form factor.
Implementation Method 1
In VCM technology, a permanent (or 'fixed') magnet and a coil are used to create actuation force. The coil is positioned in the vicinity of the magnetic field of the fixed magnet. Upon driving current in the coil, a Lorentz force is created on the coil
Implementation Method 2
a permanent (or 'fixed') magnet and a coil are used to create actuation force. The coil is positioned in the vicinity of the magnetic field of the fixed magnet. Upon driving current in the coil, a Lorentz force is created on the coil
Implementation Method 3
Another typical mechanical rail is known in the art a 'ball-guided rail', see e.g. U.S. Pat. No. 8,810,714. With a ball-guided rail, the lens is bound to move in the desired direction by set of balls confined in a groove
Implementation Method 4
utilizing ferromagnetic yokes and Hall bar position sensors for precise control
Data Source
AI summary
Actuators for carrying and actuating a lens having a first optical axis, the lens receiving light folded from a second optical axis substantially perpendicular to the first optical axis, comprising first and second VCM engines coupled to the lens and first and second linear ball-guided rails operative to create movement of the lens in two substantially orthogonal directions upon actuation by respective VCM engines.