Lens Drive Corner Magnet Layout for Compact Camera Autofocus

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Solution Overview

Problem

Existing camera modules face challenges in miniaturizing voice coil motor (VCM) technology to accommodate subminiature, low-power camera modules, particularly in achieving high-resolution imaging with autofocusing, handshake correction, and zooming while maintaining a compact size.

Innovation Solution

A lens moving apparatus with a housing, bobbin, coil, magnet, and position sensor configuration that includes a unique arrangement of magnets, coils, and elastic units to enable efficient movement of lenses while minimizing size, allowing for a large lens aperture and space for a drive-type position sensor, thereby improving design flexibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If VCM technology is miniaturized for subminiature camera modules, then product size is reduced, but it becomes difficult to mount a large lens aperture and ensure space for position sensors

Engineering Contradiction:

Improveproduct sizeVSAvoidlens aperture area

Core Design Contradiction:

Volume of moving objectVSArea of stationary object

Solution Approach 1:

The patent applies asymmetric arrangement of magnets within the housing, positioning magnets at specific corners (first and second corner portions) rather than symmetric distribution. This asymmetric configuration optimizes the magnetic field for driving the coil while creating asymmetric available spaces that can accommodate both the lens aperture and position sensor in a compact form factor.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent utilizes three-dimensional spatial optimization by strategically positioning the position sensor at specific locations (third corner portion) and arranging magnets and coils in different spatial planes. This dimensional arrangement allows the lens aperture to be maximized in the optical path while maintaining compact overall dimensions, effectively using vertical and lateral spaces efficiently.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Force

If magnets are added for driving the coil, then lens movement capability is improved, but space for position sensor is reduced

Engineering Contradiction:

Improvelens driving forceVSAvoidposition sensor space

Core Design Contradiction:

ForceVSArea of stationary object

Solution Approach 1:

The patent divides the magnetic driving system into multiple discrete magnets positioned at different corner portions of the housing. This segmentation allows the magnetic force to be distributed and optimized for driving the coil while creating distinct spatial zones that can accommodate the position sensor without interference from the magnetic components.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent creates different local qualities within the housing by positioning magnets only at specific corner portions (first and second corners) while leaving other areas (third corner portion) free for the position sensor. This localized arrangement ensures strong driving force where needed while preserving space for sensing components.

Inventive Principle:

Principle #3Local quality

3Measurement precision

If circuit board is positioned for sensor mounting, then position sensing is enabled, but magnetic interference may occur from nearby magnets

Engineering Contradiction:

Improveposition sensor accuracyVSAvoidmagnetic interference

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the position sensor from areas near the magnets by positioning it at the third corner portion, which is spatially separated from the magnetic components located at the first and second corner portions. This extraction eliminates magnetic interference from affecting the position sensor's measurement accuracy while maintaining compact overall design.

Inventive Principle:

Principle #2Taking out (Extraction)

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

Enables the mounting of a large lens aperture in a reduced product size, ensuring space for a drive-type position sensor and enhancing design freedom, facilitating high-resolution imaging and autofocusing functions in compact camera modules.

Implementation Method 1

a coil disposed on the bobbin, and a magnet disposed on the housing so as to face the coil

Methodology Applied

Scientific EffectElectromagnetic force: Lorentz Force

Implementation Method 2

a circuit board disposed on one side surface of the housing and including a position sensor, and a sensing magnet disposed on the bobbin so as to face the position sensor

Methodology Applied

Scientific EffectMagnetic field sensing: Magnetic Field

Data Source

PatentUS20250004292A1Lens driving apparatus, and camera module and optical device comprising same

Publication Date: 2025.01.02 LG INNOTEK CO LTD

AI summary

An embodiment comprises: a housing including a first corner portion, a second corner portion, a third corner portion, and a fourth corner portion; a bobbin disposed within the housing; a coil disposed on the bobbin; a magnet disposed in the housing while being arranged opposite to the coil; a circuit board disposed on one side of the housing and including a position sensor; and a sensing magnet disposed on the bobbin while being arranged opposite to the position sensor, wherein: the magnet comprises a first magnet disposed in the first corner portion of the housing, and a second magnet disposed in the second corner portion opposite to the first corner portion of the housing; the position sensor is disposed closer to the third corner portion than to the first corner portion; and no magnet is disposed in the third corner portion of the housing.