Lens Bobbin Layout With Position Feedback for Faster Autofocus
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Solution Overview
Problem
Conventional micro digital cameras require a long auto-focusing time due to inefficient space utilization of the bobbin and lack of feedback on lens displacement in the optical axis direction.
Innovation Solution
A lens moving apparatus with improved space efficiency and feedback mechanism for lens displacement, utilizing a bobbin that reciprocates in the optical axis direction, supported by elastic members and magnetic interaction, to enhance auto-focusing speed and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional micro digital camera lens moving apparatus is used, then the structure is simple, but the auto-focusing time is long
Solution Approach 1:
The patent incorporates a feedback mechanism where a position sensor detects the actual position of the lens during movement and feeds this information back to a controller. The controller adjusts the driving force based on this feedback to achieve precise focus alignment, significantly reducing the focus alignment time compared to conventional open-loop systems.
Solution Approach 2:
The patent implements a preliminary action by pre-positioning the lens using feedback control before the actual focusing operation. The system first moves the lens to a predicted position based on feedback from the position sensor, then makes fine adjustments to achieve precise focus, thereby reducing overall focusing time.
2Volume of moving object
If the bobbin space is not optimized, then the structure is simple, but the space efficiency is poor
Solution Approach 1:
The patent applies nesting by placing the position sensor, magnetic bodies, and other components inside the bobbin structure or in nested arrangements. The coil is wound around the bobbin, and the position sensor is positioned within the magnetic field generated by the bobbin, maximizing space utilization without significantly increasing structural complexity.
Solution Approach 2:
The bobbin structure is designed to serve multiple functions: it acts as the moving component for lens positioning, generates the magnetic field for interaction with the coil, houses the position sensor, and provides structural support. This multi-functionality improves space efficiency while maintaining reasonable structural complexity.
3Loss of time
If feedback mechanism is added for lens displacement, then the focus alignment time is shortened, but the device complexity increases
Solution Approach 1:
The patent implements a feedback system using a position sensor that detects lens displacement and provides this information to a controller. The controller uses this feedback to adjust the coil current to achieve precise focus alignment, significantly reducing focus alignment time despite the added complexity of the feedback components.
Solution Approach 2:
The patent replaces complex mechanical feedback mechanisms with an electromagnetic sensing system. Instead of using mechanical linkages or contact-based position detection, the system uses magnetic field interaction and electromagnetic sensing to detect lens position and provide feedback, reducing mechanical complexity while maintaining feedback functionality.
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 and improves the auto-focusing function while maintaining durability and space efficiency.
Implementation Method 1
a coil 120 provided on the bobbin 110, and driving magnets 130 and a sensing unit sensing a movement of the bobbin 110 in the optical axis direction
Implementation Method 2
supported by elastic members
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A lens moving apparatus, comprising: 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; a driving magnet disposed on the housing; a coil provided at an outer surface of the bobbin; an elastic member supporting the bobbin; a sensing magnet coupled to the bobbin; and a position sensor disposed at a position corresponding to the sensing magnet and coupled to a printed circuit board, wherein the position sensor is configured to sense a displacement of the sensing magnet in the first direction, wherein the bobbin comprises a reception recess formed on the outer surface of the bobbin to receive the sensing magnet, wherein the sensing magnet is disposed in the reception recess and does not protrude from an outer side surface of the bobbin, and wherein the coil is disposed between the sensing magnet and the position sensor.