Compact Camera Module with Shared Rotating Magnet for Zoom and Autofocus

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Solution Overview

Problem

Compact camera designs face challenges in reducing the size of lens modules due to the bulkiness of motors and gear or screw mechanisms used for zoom and autofocus functions, which are often offset from the optical axis, necessitating a more compact design that shares a magnet for both functions.

Innovation Solution

A compact camera module design where a stepping motor with a shared magnet is centered on the optical axis, using two stationary coils to alternate the lens groups for zoom and a third coil for autofocus, allowing the shared magnet to rotate and drive both functions efficiently.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If separate actuators and magnets are used for zoom and autofocus functions, then the reliability and functionality are improved, but the device size and complexity increase

Engineering Contradiction:

Improvezoom and autofocus functionalityVSAvoidcamera module size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent combines the zoom actuator and autofocus actuator into a single integrated actuator assembly. The rotating magnet serves dual purposes: when rotated by the stationary coils, it drives zoom through the guide mechanism, and when held stationary, it interacts with the voice coil to enable autofocus. This merging of functions into a single magnetic component significantly reduces the overall number of parts and volume of the camera module.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The rotating magnet is designed as a universal component that performs multiple functions. It acts as both the rotating element for zoom actuation and the stationary magnetic target for autofocus actuation. This multi-functionality eliminates the need for separate magnets and actuators, directly addressing the volume reduction goal while maintaining both zoom and autofocus capabilities.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Ease of manufacture

If motors are located at the side of the lenses offset from the optical axis, then the manufacturing and assembly are simplified, but the device compactness and symmetry are worsened

Engineering Contradiction:

Improvemotor assemblyVSAvoidmodule compactness

Core Design Contradiction:

Ease of manufactureVSShape

Solution Approach 1:

The patent employs asymmetric coil placement around the optical axis to generate rotational torque on the magnet. The stationary coils are positioned at specific angular locations (e.g., 0°, 90°, 180°, 270°) to create controlled magnetic fields that rotate the magnet. This asymmetric arrangement enables compact on-axis motor placement while maintaining ease of manufacture through standardized coil configurations.

Inventive Principle:

Principle #4Asymmetry

3Device complexity

If a shared magnet is used for both zoom and autofocus, then the device complexity and volume are reduced, but the manufacturing precision and control are worsened

Engineering Contradiction:

Improvenumber of componentsVSAvoidmagnet positioning

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The system dynamically switches between two operational modes for the shared magnet: rotation mode for zoom and stationary mode for autofocus. The control system activates different coil sets to achieve the desired mode, allowing precise control over the magnet's behavior. This dynamic operation enables a single magnet to fulfill both functions with high precision despite the simplified mechanical structure.

Inventive Principle:

Principle #15Dynamics

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 design achieves a more compact camera module size while maintaining effective zoom and autofocus capabilities, reducing the overall volume and increasing design compactness by utilizing a shared magnet for both functions.

Implementation Method 1

A compact camera module is desired that locates the step motor around the optical axis. A compact camera module is desired that shares a magnet for the step motor with both the zoom function and the autofocus function.

Methodology Applied

Scientific EffectElectromagnetic interaction: Electromagnetic Induction

Implementation Method 2

two stationary coils to alternate the lens groups for zoom and a third coil for autofocus, allowing the shared magnet to rotate and drive both functions efficiently

Methodology Applied

Scientific EffectMagnetic field interaction: Magnetic Field

Data Source

PatentUS9217841B2Compact camera module with zoom and auto-focus actuators sharing the same rotating annular magnet with alternating thick and thin poles

Publication Date: 2015.12.22 HONG KONG APPLIED SCI & TECH RES INST

AI summary

A compact camera modules has first, second, and third lens groups that move along an optical axis. A stepping motor is centered on the optical axis rather than offset from the optical axis. The motor has two coils that are fixed in place and a shared rotating magnet. The magnet is attached to a rotating guide that has slots to move the first and second lens groups as it rotates. The two coils are alternately energized to rotate the magnet, the rotating guide, and to move the first and second lens groups for zoom. The magnet has alternating thicker and thinner segments of opposite polarity. The thicker segments exert a greater force on an autofocus coil that is energized to move the third lens for the autofocus function. The same shared rotating magnet is used for both zoom and autofocus functions. A more compact design is possible using a shared magnet.