Aperture Driving Apparatus Vibration Control via Gravity Alignment

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Solution Overview

Problem

The existing aperture driving apparatus using a voice coil motor experiences vibration issues during closed-loop control due to an asymmetric magnet configuration, which generates unnecessary torque and affects the precision of the aperture plate's position control.

Innovation Solution

The apparatus is designed with a swing unit and a stationary unit, where the center of gravity of the swing unit is aligned with the driving force applied by the voice coil motor, using a balancer to ensure that the torque is applied in the correct direction, thereby preventing vibration during closed-loop control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a pair of magnets are disposed on both sides of the coil in the direction of the swing axis, then the magnetic path efficiency is enhanced, but the dimension in the direction of the swing axis becomes large

Engineering Contradiction:

Improvevoice coil motor efficiencyVSAvoiddimension in swing axis direction

Core Design Contradiction:

PowerVSLength of moving object

Solution Approach 1:

The patent applies asymmetry by disposing only one magnet on one side of the coil in the swing axis direction, rather than symmetrically placing magnets on both sides. This asymmetric configuration reduces the dimension in the swing axis direction while maintaining the essential magnetic path functionality through the yoke structure.

Inventive Principle:

Principle #4Asymmetry

2Length of moving object

If only one magnet is disposed on one side of the coil in the direction of the swing axis, then the dimension in the swing axis direction is reduced, but unnecessary torque is generated causing vibration

Engineering Contradiction:

Improvedimension in swing axis directionVSAvoidvibration due to unnecessary torque

Core Design Contradiction:

Length of moving objectVSObject-generated harmful factors

Solution Approach 1:

The patent applies the counterweight principle by positioning the center of gravity of the swing unit to align with the point where the driving force is applied to the coil. This balancing arrangement counteracts the generation of unnecessary torque, thereby preventing vibration during closed-loop control operation.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The patent employs closed-loop control with feedback mechanisms to detect and correct position deviations of the aperture plate. The control system uses position detection feedback to adjust the driving force, which helps suppress vibration caused by the asymmetric magnet configuration while maintaining precise position control.

Inventive Principle:

Principle #23Feedback

3Device complexity

If a fan-shaped coil is used with winding axis aligned with swing axis direction, then the coil configuration is simple, but the dimension in the swing direction becomes large

Engineering Contradiction:

Improvecoil configuration simplicityVSAvoiddimension in swing direction

Core Design Contradiction:

Device complexityVSArea of moving object

Solution Approach 1:

The patent applies asymmetry by orienting the rectangular coil's winding axis perpendicular to the swing axis direction, rather than parallel as in conventional fan-shaped coils. This asymmetric orientation, combined with the yoke structure, achieves compact dimensions in the swing direction while maintaining magnetic path efficiency.

Inventive Principle:

Principle #4Asymmetry

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 effectively reduces unnecessary torque and vibration, allowing for precise control of the aperture plate's position and miniaturization of the apparatus in the swing axis direction.

Implementation Method 1

a coil 4 that constitute a voice coil motor for obtaining a driving force for driving the aperture driving plate

Methodology Applied

Scientific EffectElectromagnetic force: Lorentz Force

Implementation Method 2

an angle sensor that detects the swing angle of the swing arm

Methodology Applied

Scientific EffectPosition detection:

Data Source

PatentUS7868575B2Aperture driving apparatus and projection type image display apparatus

Publication Date: 2011.01.11 RAKUTEN GROUP INC

AI summary

An aperture driving apparatus includes a swing unit and a stationary unit. The swing unit includes an aperture plate that partially blocks a light, a coil that constitute a voice coil motor for obtaining a driving force for driving the aperture driving plate, and a swing arm that supports the aperture plate and the coil and has a bearing portion between the aperture plate and the coil. The stationary unit includes a swing shaft that engages the bearing portion and swingably supports the swing arm about a swing axis, and a magnet and a yoke that constitute the voice coil motor together with the coil. A control unit of the aperture driving apparatus controls the swing angle of the swing arm using a closed-loop control technique. In the direction of the swing axis, the position of a center of gravity of the swing unit is substantially aligned with a position at which the driving force is applied to the coil.