Camera Assembly Motor Positioning for EMI Reduction
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Solution Overview
Problem
Optical image stabilization motors in mobile devices cause electromagnetic interference with image sensors, leading to stripe noise and reduced image quality due to the use of PWM signals in SMA actuator wires.
Innovation Solution
The camera assembly design includes an optical image stabilization motor with a non-movable and movable image stabilization component, where the drive wire is configured to minimize interference by positioning the motor far from the image sensor, and using a focusing motor with reduced electromagnetic interference, such as a voice coil or piezoelectric motor, to facilitate compensation displacement without affecting light transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an optical image stabilization motor using SMA actuator wires with PWM signals is used to perform motion compensation, then optical image stabilization function is achieved, but electromagnetic interference occurs on the image sensor causing stripe noise
Solution Approach 1:
The patent extracts the harmful electromagnetic radiation source (optical image stabilization motor) from the vicinity of the image sensor by positioning it on the opposite side of the housing. The motor remains functional for optical image stabilization but is spatially separated from the sensitive image sensor to eliminate electromagnetic interference and stripe noise.
Solution Approach 2:
The housing structure serves as an intermediary barrier between the optical image stabilization motor and the image sensor. By placing the motor on one side of the housing and the image sensor on the opposite side, the housing acts as a physical shield that blocks electromagnetic radiation from reaching the image sensor.
2Volume of moving object
If the optical image stabilization motor is positioned close to the image sensor for compact design, then device size is reduced, but electromagnetic interference affects image quality
Solution Approach 1:
Instead of reducing the distance between the motor and image sensor in the traditional layout, the patent repositions the motor along a different spatial dimension - specifically, on the opposite side of the housing from the image sensor. This dimensional rearrangement maintains compact overall device size while achieving sufficient separation to prevent electromagnetic interference.
3Adaptability or versatility
If a focusing motor is used in addition to the optical image stabilization motor, then auto-focusing function is added, but electromagnetic interference and device complexity increase
Solution Approach 1:
The patent merges the focusing motor and optical image stabilization motor into a single integrated motor assembly. Both functions (auto-focusing and optical image stabilization) are achieved using the same motor unit, which reduces device complexity while maintaining adaptability and versatility.
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 significantly reduces electromagnetic interference, improving image quality by minimizing stripe noise and maintaining effective optical image stabilization, thus enhancing the photographing experience.
Implementation Method 1
an electrical signal, such as a pulse width modulation (PWM) signal, that is input to a SMA wire causes interference to an image sensor
Implementation Method 2
an electrical signal, such as a pulse width modulation (PWM) signal, that is input to a SMA wire
Data Source
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AI summary
This application provides a camera assembly and a mobile terminal. For an optical image stabilization motor with relatively large electromagnetic radiation, for example, a SMA motor, the SMA is disposed on a lighting side of the lens assembly. Because an image sensor is located on an imaging side of the lens assembly, this can achieve a relatively long physical distance between the SMA motor and the image sensor, thereby reducing electromagnetic interference caused by the SMA motor to the image sensor.