Lens Bobbin Position Feedback for Faster Auto-Focus
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Solution Overview
Problem
Conventional micro digital cameras in IT products require a long auto-focusing time, which hinders rapid and accurate lens alignment at the focal distance, affecting the auto-focusing function and space efficiency.
Innovation Solution
A lens moving apparatus with a housing supporting driving magnets and a bobbin with a coil, utilizing electromagnetic interaction and magnetic bodies for precise movement and feedback, enhancing the auto-focusing speed and space efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a conventional lens moving apparatus is used, then the structure is simple, but the auto-focusing time is long
Solution Approach 1:
The patent implements nesting by placing the sensing unit inside the bobbin structure, specifically positioning the sensing magnet within the bobbin and the position sensor within the housing that accommodates the bobbin. This nested arrangement allows the sensing components to be integrated within the existing moving apparatus structure, adding feedback functionality without significantly increasing overall device complexity or volume.
Solution Approach 2:
The patent applies feedback by introducing a sensing unit that detects the position of the bobbin during lens movement and provides real-time position information to a controller. The controller uses this feedback to adjust the driving current to the coil, enabling precise stopping at the focal distance and significantly reducing auto-focusing time compared to conventional open-loop systems.
2Volume of moving object
If the lens moving apparatus is miniaturized, then space efficiency improves, but the auto-focusing speed decreases
Solution Approach 1:
The patent reduces the bobbin volume by nesting the sensing magnet inside the bobbin structure rather than adding external sensing components. This integrated approach minimizes the increase in bobbin volume while incorporating the feedback mechanism, thereby maintaining space efficiency in miniaturized camera modules.
Solution Approach 2:
The feedback mechanism enables faster and more precise lens positioning by allowing the system to detect the bobbin's position in real-time and adjust the driving current accordingly. This prevents overshooting and reduces the time required to achieve accurate focus, thereby improving auto-focusing speed even in miniaturized configurations.
3Measurement precision
If a sensing unit is added to the bobbin, then the auto-focusing accuracy improves, but the bobbin volume increases
Solution Approach 1:
The patent minimizes the volume increase by nesting the sensing magnet within the bobbin's internal structure. The sensing magnet is positioned within the coil's magnetic field region, allowing it to be accommodated within the existing bobbin volume without requiring significant additional space, thus maintaining compactness while enabling precise position detection.
Solution Approach 2:
The patent replaces mechanical position detection methods with a magnetic sensing system. The sensing unit utilizes electromagnetic interaction between the sensing magnet and position sensor, substituting mechanical linkages or contact-based sensors with a non-contact magnetic field-based detection system, which requires minimal additional space while providing high measurement precision.
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 apparatus significantly reduces auto-focusing time, improves the accuracy and speed of lens alignment, and enhances the auto-focusing function while optimizing space utilization.
Implementation Method 1
a bobbin including a coil disposed on the outer surface thereof inside the driving magnets, and moving in a first direction parallel with an optical axis within the housing by electromagnetic interaction between the driving magnets and the coil
Implementation Method 2
magnetic bodies provided between the driving magnets and the coil so as to be mounted on the driving magnets and to surface-contact the coil
Implementation Method 3
a sensing unit sensing a movement of the bobbin in the first direction
Data Source
AI summary
A lens moving apparatus can include a housing; a base disposed below the housing; a bobbin disposed inside the housing and configured to move in a first direction along or parallel with an optical axis within the housing; driving magnets disposed on the housing; a coil provided at an outer surface of the bobbin; an elastic member coupled to the bobbin and supporting the bobbin; a sensing magnet coupled to the bobbin; and a position sensor coupled to a printed circuit board, wherein the position sensor is configured to sense a displacement of the sensing magnet in the first direction, in which the bobbin includes a reception recess formed on the outer surface of the bobbin such that at least a part of the reception recess is located at an inside of the coil, the sensing magnet is disposed in the reception recess, and the position sensor is disposed on another side of the housing than sides on which the driving magnets are disposed.