Lens Driving Module with Coil-Based AF Position Sensing
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Solution Overview
Problem
Conventional camera modules with autofocus feedback functions face challenges in reducing size due to the need for additional components for detecting lens position, making them unsuitable for smartphones with limited space.
Innovation Solution
A lens driving device is designed to minimize the overall size of the camera module by using a sensing coil instead of a sensing magnet to provide a magnetic field to the position sensor, and by optimizing the arrangement of magnets and coils to balance electromagnetic forces and reduce current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sensing magnet is used to provide a magnetic field to the position sensor, then the magnetic field is stable, but magnetic field interference occurs between adjacent lens driving devices
Solution Approach 1:
The patent replaces the sensing magnet (magnetic field source) with a sensing coil (electromagnetic field source). The position sensor detects the magnetic field generated by the sensing coil instead of a permanent magnet, eliminating magnetic field interference between adjacent devices while maintaining stable field detection through controlled current supply to the coil.
Solution Approach 2:
The patent changes the operational state of the magnetic field source from a static permanent magnet to a dynamically controllable coil. By controlling the current through the sensing coil, the magnetic field strength and presence can be adjusted, allowing the field to be stable during operation but absent or minimal when not needed, thus preventing interference with adjacent devices.
2Measurement precision
If additional components are added for detecting lens position in autofocus feedback function, then autofocusing accuracy is improved, but the overall size of the camera module increases
Solution Approach 1:
The sensing coil serves multiple functions: it provides the magnetic field for position detection during autofocus operation, and it can also serve as part of the electromagnetic actuation system. This multi-functionality allows accurate position sensing without adding separate dedicated components that would increase module size.
Solution Approach 2:
The patent merges the position sensing function with the existing electromagnetic actuation structure by using the sensing coil integrated into the motor assembly. The coil that generates electromagnetic force for lens movement also generates the detectable magnetic field for position feedback, combining sensing and actuation functions in a single component structure.
3Use of energy by moving object
If the weight of the OIS moving part is reduced, then current consumption is reduced, but structural strength may be compromised
Solution Approach 1:
The patent employs composite material structures in the OIS moving part design, combining materials with different properties to achieve optimal strength-to-weight ratio. By using composite materials, the structure maintains sufficient mechanical strength while minimizing weight, thereby reducing the current consumption required for optical image stabilization operation.
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 solution effectively prevents malfunction of AF drive due to magnetic field interference, enhances autofocusing accuracy, and minimizes the camera module's size, while also reducing current consumption by reducing the weight of the OIS moving part.
Implementation Method 1
A lens driving device is designed to minimize the overall size of the camera module by using a sensing coil instead of a sensing magnet to provide a magnetic field to the position sensor
Implementation Method 2
the first position sensor detects the strength of the magnetic field of the sensing coil and outputs an output signal
Implementation Method 3
a first coil comprising a first cod unit corresponding to the first magnet and a second coil unit corresponding to the second magnet
Implementation Method 4
an elastic member coupled to the bobbin and the housing
Data Source
AI summary
The present embodiment relates to a lens driving device which includes: a substrate; a housing; a bobbin; a sensing coil; a first magnet; a second magnet; a third magnet; a dummy member; a first coil that includes a first coil unit and a second coil unit; and a first position sensor that is disposed on the substrate and corresponds to the sensing coil, wherein the first magnet and the second magnet are positioned on opposite sides from each other, the third magnet and the dummy member are positioned on opposite sides from each other, the sensing coil is provided with a driving signal, and the first position sensor senses the strength of the magnetic field of the sensing coil and outputs an output signal.