Camera Lens Actuator Magnet Layout for Stable Autofocus
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Solution Overview
Problem
Conventional lens driving apparatuses have limited design freedom due to the fixed placement of detection magnets, which restricts the degree of freedom in the placement of magnetic components and thus limits the design of the apparatus.
Innovation Solution
A lens driving apparatus with a detection magnet positioned closer to the first magnetic field generating member than the second, and a balance magnet positioned closer to the second magnetic field generating member, allowing for increased design flexibility by stabilizing the lens holding member and reducing the overall size of the apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the detection magnet is placed at a fixed position in conventional lens driving apparatuses, then the position detection function is achieved, but the design freedom for placing magnetic components is limited
Solution Approach 1:
The patent applies asymmetry by introducing a balance magnet on the opposite side of the detection magnet relative to the optical axis. This asymmetric configuration of two magnets allows the detection magnet to be positioned closer to one magnetic field generating member while the balance magnet compensates for magnetic field imbalance, thereby achieving both position detection and design flexibility without compromising system symmetry requirements
Solution Approach 2:
The balance magnet functions as a counterweight in the magnetic field domain. By placing a balance magnet with opposite polarity on the opposite side of the optical axis, the patent counterbalances the magnetic field influence of the detection magnet, allowing the detection magnet to be positioned asymmetrically closer to one magnetic field generating member while maintaining overall magnetic field equilibrium
2Adaptability or versatility
If the detection magnet is positioned closer to one magnetic field generating member, then design flexibility is increased, but magnetic field imbalance may affect detection accuracy
Solution Approach 1:
The balance magnet with opposite polarity compensates for the magnetic field imbalance created by positioning the detection magnet closer to one magnetic field generating member. This counterbalancing arrangement ensures that the net magnetic field influence on the lens holding member remains balanced, maintaining position detection accuracy while allowing asymmetric placement of the detection magnet
3Stability of the object's composition
If the lens holding member is stabilized with additional magnets, then the stability is improved, but the apparatus size may increase
Solution Approach 1:
The patent merges multiple functions into the two magnets: the detection magnet serves both as a position indicator for the Hall element and as part of the magnetic field interaction system, while the balance magnet simultaneously provides magnetic field compensation and structural balancing. This functional merging achieves stability without requiring additional separate components that would increase apparatus volume
Solution Approach 2:
The detection magnet performs multiple functions: it generates the magnetic field detected by the Hall element for position detection, and it participates in the magnetic field interaction with the magnetic field generating members for lens driving. The balance magnet similarly serves multiple purposes including magnetic field compensation and structural balancing, achieving stability without increasing apparatus dimensions
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 enhances the stability of the lens holding member, reduces the apparatus's dimensions, and improves the autofocus adjustment function by allowing for more flexible placement of magnetic components, thereby increasing design freedom.
Implementation Method 1
a coil held in the lens holding member
Implementation Method 2
a first magnetic field generating member and a second magnetic field generating member facing each other across the coil and the lens holding member
Implementation Method 3
The position of the lens holding member is derived from the output of a Hall element attached to a fixed side member so as to face the detection magnet
Data Source
AI summary
A lens driving apparatus includes a housing; a lens holding member positioned in the housing for holding a lens body, a coil, a detection magnet, and a balance magnet; first and second magnetic field generating members facing each other across the coil and the lens holding member; the detection magnet for detecting a position of the lens holding member; a magnetic detection member facing the detection magnet; the balance magnet facing the detection magnet across an optical axis of the lens body; and first and second leaf springs conducted to the ends of the coil, movably supporting the lens holding member in the optical axis direction. The detection magnet is disposed closer to the first magnetic field generating member than to the second magnetic field generating member, and the balance magnet is disposed closer to the second magnetic field generating member than to the first magnetic field generating member.