Lens Drive Coil Layout for Stable OIS Position Sensing
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Solution Overview
Problem
Existing lens driving technologies for micro-scale, low-power camera modules face challenges in reducing the influence of induction magnetic fields on OIS position sensors and ensuring stability and reliability of optical image stabilization feedback control.
Innovation Solution
The lens moving apparatus is designed with a second coil and a third coil having a loop shape, wound clockwise or counterclockwise about the optical-axis, where the third coil overlaps the position sensor in the optical-axis direction, and the intensity of the second magnetic field is smaller than that of the third magnetic field, with specific coil configurations and housing features to minimize interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the OIS coil is positioned close to the position sensor to improve OIS control precision, then the magnetic field intensity increases, but the induction magnetic field interference on the position sensor worsens
Solution Approach 1:
The patent introduces a magnetic shielding layer as an intermediary between the OIS coil and the position sensor. This shielding layer blocks or attenuates the induction magnetic field generated by the OIS coil, preventing it from interfering with the position sensor while allowing the magnetic field from the permanent magnet to reach the sensor for accurate position detection.
Solution Approach 2:
The patent divides the magnetic field environment into distinct zones by placing the magnetic shielding layer selectively. The shielding layer segments the magnetic field paths, allowing the position sensor to detect the permanent magnet's field without contamination from the OIS coil's induction field, thus resolving the interference problem while maintaining detection precision.
2Reliability
If the number of turns in the OIS coil is increased to strengthen the magnetic field for better stabilization, then the OIS effect improves, but the induction magnetic field interference on the position sensor increases
Solution Approach 1:
The magnetic shielding layer acts as a mediator that allows the system to use a higher number of OIS coil turns for improved stabilization performance while blocking the harmful induction magnetic field from reaching the position sensor. This enables the system to achieve better OIS reliability without sacrificing position detection accuracy.
3Reliability
If the OIS coil is wound with more turns to increase magnetic field intensity, then the handshake correction capability improves, but the complexity of coil configuration and manufacturing increases
Solution Approach 1:
The magnetic shielding layer provides a straightforward structural solution that enables the use of multi-turn OIS coils for improved handshake correction reliability. By adding this shielding component, the system can achieve better performance without proportionally increasing manufacturing complexity, as the shielding layer can be integrated into the existing coil assembly structure.
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 effectively reduces the influence of induction magnetic fields on OIS position sensors, ensuring stable OIS feedback control and reliable handshake correction in camera modules.
Implementation Method 1
a second coil (230) disposed on the circuit board (250), wherein the second coil (230) generates a second magnetic field
Implementation Method 2
a third coil (260) disposed between the second position sensor (240) and the second coil (230), wherein the third coil (260) generates a third magnetic field
Implementation Method 3
a first magnet (130) disposed on the housing (140) so as to overlap the second coil (230) in the optical-axis direction (OA)
Data Source
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AI summary
One embodiment comprises: a housing; a bobbin arranged in the housing so as to mount a lens therein; a magnet arranged in the housing; a first coil, which is arranged in the bobbin and moves in the optical axial direction according to an interaction with the magnet; an elastic member coupled with the bobbin and the housing; a second coil to which a first drive signal is applied, and moving the housing in a direction perpendicular to the optical axial direction according to the interaction with the magnet; a location sensor for sensing the strength of the magnetic field of the magnet according to the movement of the housing; and a third coil to which a second drive signal is applied, and is arranged in correspondence with the location sensor, wherein a first magnetic field, of the second coil, which is generated by the first drive signal, and a second magnetic field, of the third coil, which is generated by the second drive signal, are generated in directions offsetting each other.