Voice Coil Motor Floating Device Stabilization for Image Sensor Protection
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Solution Overview
Problem
Conventional voice coil motors in auto focus devices of mobile communication apparatuses suffer from image quality degradation due to particle generation during drop tests, as the floating device vibrates and collides with the inner surface, causing black dots or shadow regions on images.
Innovation Solution
An auto focus device with a voice coil motor, a first driving circuit for moving the floating device during camera use, and a second driving circuit to fix the floating device with a reverse electric current when the camera is not in use, featuring an outward inclined structure to prevent particles from reaching the image sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a floating device is used in the voice coil motor to perform auto focus, then the auto focus function can be achieved through movement of the floating device, but the floating device will randomly move and collide with the inner surface during drop test to generate particles that degrade image quality
Solution Approach 1:
The patent applies preliminary anti-action by providing a driving circuit that applies a predetermined reverse voltage to the voice coil motor when the camera is not in use. This reverse voltage creates a magnetic field that counteracts any random movement of the floating device, preventing it from colliding with the inner surface and generating particles before such damage can occur. The protective action is taken in advance during idle periods to prevent future image quality degradation.
Solution Approach 2:
The patent implements preliminary action by continuously applying a reverse voltage to the voice coil motor when the camera function is not active. This keeps the floating device in a predetermined stable position before any drop test or improper use occurs. By maintaining this protective state in advance, the system ensures the floating device is already secured and cannot move randomly to generate particles that would affect image quality.
2Ease of operation
If the floating device is allowed to move freely for auto focus operation, then auto focus performance is achieved, but the floating device vibrates irregularly during drop test causing particles to fall on image sensor
Solution Approach 1:
The patent applies dynamics by switching the voice coil motor between two operational states: during camera use, the motor operates dynamically to move the floating device for auto focus; during idle periods, a reverse voltage is applied to dynamically adjust the magnetic field to hold the floating device stationary. This dynamic state switching allows the system to enjoy the benefits of free movement when needed while preventing harmful particle generation when the camera is not in use.
Solution Approach 2:
The patent implements parameter changes by altering the electrical parameter (voltage) applied to the voice coil motor. When the camera is in use, a forward voltage enables auto focus movement. When idle, a predetermined reverse voltage is applied to change the magnetic field direction and strength, thereby changing the floating device's state from movable to fixed, preventing particle generation without affecting auto focus performance when needed.
3Device complexity
If no reverse voltage is applied to fix the floating device during idle time, then the voice coil motor remains simple to operate, but the floating device will collide with inner surface and generate particles degrading image quality
Solution Approach 1:
The patent applies self-service by implementing an automatic control mechanism that monitors camera usage state and automatically applies the appropriate voltage to the voice coil motor. When the camera is not in use, the system automatically applies a reverse voltage to secure the floating device, and when the camera is in use, it automatically switches to forward voltage for auto focus operation. This self-service approach maintains image quality without requiring manual intervention, making the additional protective function transparent to the user.
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
Prevents image quality degradation by stabilizing the floating device during drop tests and improper use, ensuring no particles fall on the image sensor, thereby enhancing product yield and image clarity.
Implementation Method 1
The floating device moves due to the interaction between the magnet and the winding coil when an electric current flows through the winding coil since the magnet surrounds the magnet
Implementation Method 2
The second driving circuit drives the voice coil motor to fix the floating device inside the voice coil motor, contact against and cover the image sensor unit when the camera function of the mobile communication apparatus is not in use
Data Source
AI summary
An auto focus device of a mobile communication apparatus is disclosed. The auto focus device comprises a voice coil motor, a first driving circuit and a second driving circuit. The voice coil motor comprises a floating movable device and a lens in the floating movable device. The first driving circuit drives the voice coil motor so that the floating movable device moves inside the voice coil motor to zoom in/out and focus the lens on image sensors when the camera function is activated. The second driving circuit drives the voice coil motor to fix the floating movable device inside the voice coil motor and cover the image sensors.