Lens Drive Device Double-Pole Magnet Magnetic Leakage Reduction
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Solution Overview
Problem
Conventional lens drive devices for mobile communication terminals face challenges in downsizing and high-density mounting due to magnetic interference with other electronic components, as the magnetic fields generated by the magnets can affect nearby devices.
Innovation Solution
The use of a double-pole magnet with specific magnetization directions and a nonmagnetic case, along with yokes to concentrate magnetic flux around coils, reduces magnetic leakage and interference, allowing for more compact and densely mounted lens drive devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a conventional magnet is used in the lens drive device, then the magnetic field can drive the lens, but magnetic flux leaks toward the outside causing interference with other electronic components
Solution Approach 1:
The patent applies local quality by creating different magnetization directions in different regions of the magnet. The magnet is divided into a first section with first magnetization direction opposing the first coil, and a second section with second magnetization direction opposing the second coil. This localized differentiation of magnetic properties confines the magnetic flux to specific regions around the coils, preventing leakage toward external areas while maintaining the driving force for lens movement.
2Volume of moving object
If the lens drive device is downsized and arranged densely, then mobile communication terminal size is reduced, but magnetic interference with other components increases
Solution Approach 1:
By implementing local quality through differentiated magnetization in the first and second sections, the patent successfully downsizes the lens drive device while preventing magnetic interference. The localized magnetic field configuration allows compact arrangement of components without causing harmful magnetic effects on neighboring electronic components, thus resolving the contradiction between miniaturization and magnetic interference prevention.
3Length of moving object
If L1 is made excessively large to increase movable range of the first coil, then focus adjustment capability is improved, but magnetic flux leaks toward the outside
Solution Approach 1:
The patent resolves this contradiction by applying local quality through the second section of the magnet with a specific magnetization direction opposing the second coil. This localized magnetic configuration allows the first coil to achieve adequate movable range for focus adjustment while the second section's magnetization directs flux away from external areas, preventing leakage even when L1 is sufficiently large for operational requirements.
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 ability to mount lens drive devices densely without interfering with other components, while also enabling downsizing and maintaining effective magnetic field concentration for lens movement, reducing magnetic interference and improving weight balance.
Implementation Method 1
a magnetic field for driving the lens is formed around the first and second coils using the double-pole magnet
Implementation Method 2
magnetic flux of the double-pole magnet can effectively concentrate around the first and second coils, and magnetic flux can be prevented from leaking toward the outside of the lens drive device
Data Source
AI summary
A lens drive device includes a movable portion, a fixed portion, and a nonmagnetic case. The movable portion includes a double-pole magnet having two pairs of magnetic poles, a first coil opposing to the double-pole magnet in a perpendicular direction to a light axis, and a lens holder being movable to the double-pole magnet in a direction of the light axis. The fixed portion includes a second coil arranged so as to oppose to the double-pole magnet in the direction of the light axis. The nonmagnetic case is attached to the fixed portion so as to cover the movable portion. The double-pole magnet includes a first section and a second section. L1/L2 is 1.1 to 2.0, where L1 and L2 are respectively a length of the first and second sections in the direction of the light axis.