Camera Shake Correction Controller with Time Rate Limiter

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Solution Overview

Problem

Existing camera shake correction systems in image capturing apparatuses face issues with false detection of vibrations due to high-frequency components like shutter-induced impact, leading to image degradation, as they either cause phase lag or reduce the correction effect.

Innovation Solution

Incorporating a time change rate limiter in the controller to limit the time rate of change of the angular velocity signal to a predetermined value, preventing excessive movement of the camera shake correction lens and thus reducing false detection without causing phase lag in the usual camera shake correction band.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the sensitivity of the angular velocity sensor is increased to detect low frequency camera shake, then the detection precision of camera shake is improved, but the sensor becomes too sensitive to disturbance such as shutter-induced impact

Engineering Contradiction:

Improvedetection precision of camera shakeVSAvoidfalse detection due to disturbance

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

A time change rate limiter is introduced as an intermediary component between the angular velocity sensor and the camera shake correction lens. This limiter filters high-frequency disturbance signals (such as shutter-induced impact) by limiting the rate of change of the sensor output, while allowing low-frequency camera shake signals to pass through. This resolves the contradiction by enabling the sensor to maintain high sensitivity for detecting camera shake without being overly sensitive to high-frequency disturbances.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the time constant of the high frequency cutoff filter is increased to reduce false detection due to shutter impact, then false detection is reduced, but phase lag occurs in the camera shake correction band

Engineering Contradiction:

Improvereduction of false detectionVSAvoidphase lag in correction band

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

Instead of using a traditional high-frequency cutoff filter with a fixed time constant, the patent employs a time change rate limiter that dynamically processes the sensor signal based on the rate of change parameter. This approach effectively reduces high-frequency disturbance components without introducing significant phase lag in the camera shake correction band, thereby resolving the contradiction between reducing false detection and maintaining real-time correction performance.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the gain in the gain controller is decreased to suppress movements due to shutter-induced impact, then false detection is reduced, but the correction amount of real camera shake is reduced

Engineering Contradiction:

Improvesuppression of false detectionVSAvoidcorrection amount of camera shake

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The time change rate limiter applies different processing characteristics to different frequency components of the sensor signal. It selectively limits high-frequency components (shutter-induced impact) while allowing low-frequency components (real camera shake) to pass through with full gain. This local differentiation in signal processing resolves the contradiction by suppressing false detection without reducing the correction amount for actual camera shake.

Inventive Principle:

Principle #3Local quality

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

Effectively reduces high-frequency components like shutter-induced impact, preventing image degradation by eliminating wrong operations in camera shake correction while maintaining effective camera shake correction within the usual frequency band.

Implementation Method 1

an angular velocity detector configured to detect an angular velocity of shake of the image capturing apparatus and generate a detection signal

Methodology Applied

Scientific EffectAngular velocity detection: Accelerometer

Implementation Method 2

a time change rate limiter configured to limit a time rate of change of angular velocity indicated by the detection signal output from the angular velocity detector to a predetermined limiting value or less

Methodology Applied

Scientific EffectTime rate of change limitation:

Implementation Method 3

a movable member that is movable on a plane perpendicular to an optical axis of the optical system to achieve the camera shake correction function

Methodology Applied

Scientific EffectMechanical movement for shake correction:

Data Source

PatentUS9077902B2Image capturing apparatus having camera shake correction function

Publication Date: 2015.07.07 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

An image capturing apparatus having a camera shake correction function, includes an optical system, a movable member that is movable on a plane perpendicular to an optical axis of the optical system to achieve the camera shake correction function, an angular velocity detector configured to detect an angular velocity of shake of the image capturing apparatus and generate a detection signal, and a controller configured to drive the movable member based on the output from the angular velocity detector. The controller includes a time change rate limiter configured to limit a time rate of change of angular velocity indicated by the detection signal output from the angular velocity detector to be no greater than a predetermined limiting value, and drive the movable member based on the detection signal output through the time change rate limiter.