Position Detection in Optical Image Stabilization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional position detecting apparatuses in optical image stabilization systems face challenges in accurately detecting the position of optical elements moved by voice coil motor (VCM) type driving mechanisms, particularly due to interference from magnetic fields generated by the coils, which affects the accuracy of position detection.
Innovation Solution
The position detecting apparatus includes a fixed member with a magnet and a movable member with a coil, where magnetism detecting members, such as Hall elements, are strategically positioned to avoid the influence of magnetic flux densities from the coils, ensuring accurate detection by placing them on imaginary lines where the sum of magnetic flux densities along the optical axis is zero, thereby minimizing noise from the VCM driving section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetism detecting members are placed near the coil to detect position, then position detection capability is improved, but magnetic flux density from the coil interferes with detection accuracy
Solution Approach 1:
The patent extracts the magnetism detecting members from the region affected by coil magnetic flux by positioning them on the optical axis where the radial magnetic flux components cancel out. This separation places the detection function in a location free from harmful magnetic interference while maintaining detection capability.
Solution Approach 2:
The optical axis serves as an intermediary space where the magnetic flux from opposite coils cancels each other out, creating a neutral zone for position detection. The detecting members are positioned in this intermediary region where harmful magnetic effects are eliminated.
2Volume of moving object
If the image stabilization apparatus is made compact to reduce size, then device miniaturization is achieved, but space for accurate position detection is reduced
Solution Approach 1:
The patent utilizes the optical axis dimension (vertical to the coil plane) as a new spatial dimension for positioning detecting members. By moving detection elements along this dimension to the center position, the system achieves accurate detection in a compact lateral footprint, effectively using vertical space to resolve horizontal space constraints.
Solution Approach 2:
The central region on the optical axis serves dual purposes: it is the focal point for optical imaging and simultaneously the optimal location for magnetic flux cancellation and position detection. This multi-functional use of the central axis space eliminates the need for separate detection zones.
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 enhances the accuracy of position detection, reduces the size of the image stabilization apparatus, and contributes to improved performance by isolating the magnetic fields' impact on the detecting members, leading to more precise image stabilization.
Implementation Method 1
a magnetism detecting member disposed in the movable member or the fixed member in which the coil is disposed, the magnetism detecting member detecting a change in a magnetic flux density of the magnet
Implementation Method 2
a movable member including a movable barrel in which another of the magnet and the coil and an optical element are disposed, the movable barrel being driven in a direction perpendicular to a direction along an optical axis of the optical element with respect to the fixed member by a VCM driving section including the magnet and the coil
Data Source
AI summary
A position detecting apparatus includes: a fixed member in which a magnet is disposed, a movable member including a movable barrel in which a coil and an optical element are disposed, the movable barrel being driven in a direction perpendicular to a direction along an optical axis of the optical element with respect to the fixed member by a VCM driving section, and a magnetism detecting member disposed in the movable member, the magnetism detecting member detecting a change in a magnetic flux density of the magnet at a time when the movable member is driven. The magnetism detecting member is disposed, in a plane perpendicular to a direction along the optical axis, in a position where a magnetic flux density of the coil does not affect the change in the magnetic flux density due to the magnet when an electric current is fed to the coil.