Voice Coil Motor Layout for Precise Lens Position Feedback
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Solution Overview
Problem
Existing voice coil motors in camera modules face challenges in precise and rapid control of lens movement due to magnetic interference, affecting focusing and anti-shake performance.
Innovation Solution
A voice coil motor design featuring radially arranged magnetic pieces, a counterweight, and strategically positioned magnetic sensors to minimize heat interference and enhance detection precision, enabling faster and more precise closed-loop control of lens movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple magnetic pieces are arranged in the voice coil motor to enable multi-directional lens control, then the control functionality is improved, but magnetic interference between magnetic pieces increases causing positioning errors
Solution Approach 1:
A magnetic sensor is introduced as an intermediary component to detect the positions of multiple magnetic pieces (first, second, and third magnetic pieces) and provide feedback signals. This allows the control circuit to calculate accurate lens positions despite magnetic interference between pieces, resolving the contradiction by using the sensor as a mediator to compensate for the interference effects.
Solution Approach 2:
The magnetic sensor provides real-time feedback on the positions of magnetic pieces to the control circuit. The control circuit uses this feedback to calculate the lens position and adjust driving currents dynamically, enabling precise control despite the presence of multiple magnetic pieces that generate interfering magnetic fields.
2Speed
If magnetic sensors are positioned close to the optical carrier for rapid detection, then detection speed is improved, but heat interference from the optical carrier affects detection precision
Solution Approach 1:
The magnetic sensor is positioned at a specific location on the optical carrier where it can detect magnetic fields from all three magnetic pieces while being thermally isolated from heat-generating components. The sensor is placed to optimize the balance between detection speed (proximity to magnetic pieces) and thermal interference avoidance (distance from heat sources).
Solution Approach 2:
The magnetic sensor acts as an intermediary that detects magnetic field changes without being directly exposed to thermal interference. By positioning the sensor on the optical carrier at a strategic location, it mediates between the need for rapid detection and the need to avoid heat-induced measurement errors.
3Device complexity
If the voice coil motor uses a simple structure without additional magnetic sensors, then device complexity is reduced, but control precision and speed deteriorate due to magnetic interference
Solution Approach 1:
The magnetic sensor serves multiple functions: it detects positions of multiple magnetic pieces, provides feedback for closed-loop control, enables calculation of lens position in three directions, and compensates for magnetic interference effects. This multi-functionality justifies the added complexity by significantly improving control precision without requiring separate components for each function.
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
Improves focusing and anti-shake performance by allowing more accurate and rapid control of lens movement, reducing the impact of heat on detection precision and minimizing magnetic interference.
Implementation Method 1
After being electrified, the first coils may drive, under actions of magnetic fields, the optical carrier to move in a direction of an optical axis with the first induction magnet
Implementation Method 2
The first magnetic sensor may convert a magnetic field signal generated by the first induction magnet into a first electrical signal, to detect a moving direction and a moving distance
Data Source
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Figure 3~4(b)
Figure 5
AI summary
This application provides a voice coil motor, a camera module, and an electronic device, and relates to the field of terminal technologies, to improve precision and increase a speed of controlling movement of a lens assembly by the voice coil motor, and further improve focusing and anti-shake performance of the camera module. The voice coil motor includes: a first magnetic piece, a second magnetic piece, a third magnetic piece, and a counterweight that are radially arranged around an optical carrier sequentially; first coils that are symmetrically fastened on two sides of the optical carrier, where one of the two coils is disposed opposite to the first magnetic piece, and the other of the two coils is disposed opposite to the third magnetic piece; and a first magnetic sensor and a first induction magnet that are oppositely disposed, where the first magnetic sensor is disposed on a side that is of the counterweight and that is close to the optical carrier, and the first induction magnet is fastened on an outer wall that is of the optical carrier and that is close to the counterweight. The first coils are configured to drive the optical carrier to move in a direction of an optical axis with the first induction magnet, and the first magnetic sensor is configured to convert a magnetic field signal generated by the first induction magnet into a first electrical signal.