Lens Driving Apparatus Hall Sensor Feedback Control
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Solution Overview
Problem
Conventional voice-coil motor (VCM) systems for auto-focusing in mobile terminals lack feedback, leading to increased focusing time and less fluent operations as the lens needs to return to its original position before focusing.
Innovation Solution
A lens driving apparatus incorporating a holder, cover, carrier, magnets, coil, spring, spacer, and a hall sensor, which detects the magnetic field variation to provide feedback and allow the lens to move directly to the focusing position without returning to its original position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional VCM with open-loop control is used, then the structure is simple, but the focusing time is long and operation is not fluent
Solution Approach 1:
The patent introduces a feedback mechanism by placing a hall sensor on the holder to detect the position of magnets attached to the carrier. This feedback signal allows the system to determine the lens position in real-time, enabling the lens to move directly to the focusing position without returning to the original position, thus reducing focusing time while maintaining operational fluency
2Loss of time
If feedback mechanism is added to detect lens position, then focusing time is reduced, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical position detection mechanisms with a magnetic field-based detection system. Magnets are attached to the carrier and a hall sensor on the holder detects their position through magnetic field variations. This substitution reduces mechanical complexity while providing accurate real-time position feedback to enable direct focusing
3Ease of operation
If hall sensor and magnets are used for feedback, then focusing operation becomes fluent, but manufacturing complexity increases
Solution Approach 1:
The patent extracts the position detection function from the mechanical structure and implements it separately using magnetic components. The magnets are attached to the carrier and the hall sensor is mounted on the holder, allowing independent optimization of each component during manufacturing while achieving fluent focusing operation through their magnetic interaction
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 solution enables faster and more fluent focusing by providing immediate feedback and allowing the lens to move directly to the focusing position, reducing the overall focusing time.
Implementation Method 1
the hall sensor is for detecting a magnetic field of any one of the second magnets, wherein the magnetic field is varied according to a relative displacement between the hall sensor and the second magnet which is detected
Implementation Method 2
The coil is wound around an outer side of the carrier, and adjacent to the first magnet
Data Source
AI summary
A lens driving apparatus includes a holder, a cover, a carrier, a first magnet, a coil, a spring, two second magnets and a hall sensor. The holder includes an opening hole. The cover is made of metal material and coupled to the holder. The carrier is movably disposed in the cover, and for coupling to a lens. The first magnet is connected to an inner side of the cover. The coil is wound around an outer side of the carrier, and adjacent to the first magnet. The spring is coupled to the carrier. The second magnets are disposed on one end of the carrier which is toward the holder. The hall sensor is for detecting a magnetic field of any one of the second magnets, wherein the magnetic field is varied according to a relative displacement between the hall sensor and the second magnet which is detected.