Optical Image Stabilization Using Digital Gyroscope and VCM

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Solution Overview

Problem

Conventional camera modules face challenges in achieving accurate optical image stabilization, robustness, cost-effectiveness, and compact size due to the complexity and additional hardware required by Hall elements and associated circuitry, which affects performance and integration in handsets and digital still cameras.

Innovation Solution

An optical image stabilization system integrating a voice coil motor, digital gyroscope, and an estimator-based controller on a single chip, eliminating the need for a Hall element and its circuitry, with a high-bandwidth gyroscope and unique control loop design for precise angular position calculation and stabilization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If Hall elements and associated circuitry are used for optical image stabilization, then position feedback is provided, but device complexity and cost increase significantly

Engineering Contradiction:

Improveposition feedback precisionVSAvoidhardware complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent removes the Hall element and its associated circuitry from the optical image stabilization system. Instead of using external position sensors, the system calculates lens module position indirectly through drive current measurements and mathematical models, thereby extracting the problematic components while maintaining stabilization functionality.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical/electrical Hall element sensing system with a computational approach using drive current measurements and mathematical models. The system substitutes direct position measurement with indirect position calculation through electrical parameter monitoring and algorithmic processing.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If Hall elements and associated circuitry are used for optical image stabilization, then position feedback is provided, but manufacturing cost increases

Engineering Contradiction:

Improveposition feedback precisionVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses readily available, low-cost components such as standard voice coil motors and basic current sensing circuitry instead of expensive Hall elements. The system relies on inexpensive mathematical modeling and control algorithms to achieve the required precision, significantly reducing bill of materials cost.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Adaptability or versatility

If conventional camera module design is used, then optical components are separate, but integration and compact size are reduced

Engineering Contradiction:

Improveintegration capabilityVSAvoidmodule size

Core Design Contradiction:

Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The patent merges the voice coil motor, control electronics, and mathematical modeling into an integrated system. The control algorithm combines drive current sensing, position calculation, and stabilization control into a unified approach, allowing compact packaging while maintaining full functionality.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent makes the drive current serve multiple functions: it both actuates the voice coil motor and provides the measurement signal for position feedback. This multi-functionality eliminates the need for separate sensing components and enables more compact integration.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

The solution provides a cost-effective, high-performance, and compact optical image stabilization system with improved robustness and reduced phase delay, capable of handling shock and vibration, while minimizing hardware complexity and power consumption.

Implementation Method 1

a force generating coil such as a voice coil motor (VCM)

Methodology Applied

Scientific EffectElectromagnetic force: Lorentz Force

Implementation Method 2

at least one digital gyroscope for receiving signals from the VCM

Methodology Applied

Scientific EffectGyroscope effect: Gyroscope

Data Source

PatentUS8170408B2Optical image stabilization in a digital still camera or handset

Publication Date: 2012.05.01 INVENSENSE INC

AI summary

An optical image stabilization system for a camera module is disclosed. The stabilization system comprises a voice coil motor (VCM), at least one digital gyroscope for receiving signals from the VCM, and an angular velocity sensor for receiving signals from the digital gyroscope and outputting an angular position error signal. The stabilization system further comprises signal processing logic for receiving the error signal, and comparing the error signal to a reference signal and providing a stabilized image based upon that comparison, wherein the hard-coded logic, digital gyroscope and rate and position sensor resides on the same chip.