Lens Drive Ball Guide Layout for Low-Height OIS and Stable AF
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Solution Overview
Problem
Conventional lens driving devices face issues with increased current consumption due to heavier magnets, increased height, and potential tilting and deviation of moving parts, particularly with larger lens diameters and hand shake correction functions.
Innovation Solution
The lens driving device integrates a lighter coil in the moving part, minimizes optical axis height by combining guide structures, and uses an elastic member to prevent centering forces and diagonal ball guides to prevent rotation and tilt.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a magnet is disposed in the moving part to perform autofocus function, then electromagnetic interaction for autofocus is achieved, but current consumption increases due to the magnet's larger weight compared to a coil
Solution Approach 1:
The patent inverts the conventional arrangement by placing the coil in the moving part and the magnet in the fixed part. This reversal reduces the weight of the moving part while maintaining electromagnetic interaction capability, as the coil is lighter than an equivalent magnet. The inverter mechanism converts the driving direction while preserving the core electromagnetic driving function.
Solution Approach 2:
The patent introduces a guide structure with guide grooves and guide protrusions as an intermediary mechanism to enable linear movement of the moving part along the optical axis. This guide structure facilitates the weight reduction by allowing the lighter coil-based moving part to achieve precise linear positioning without requiring a heavy magnet, thus mediating between the weight reduction goal and the autofocus functionality requirement.
2Ease of operation
If guide structures for OIS-x-axis and OIS-y-axis driving are disposed as separate layers, then hand shake correction is achieved, but the height of the camera device in the optical axis direction increases
Solution Approach 1:
The patent merges the guide structures for OIS-x-axis and OIS-y-axis driving into a single integrated guide structure. The guide protrusions are configured to engage with guide grooves that accommodate both x-axis and y-axis movement constraints simultaneously. This consolidation maintains the hand shake correction functionality while reducing the overall height of the camera device by eliminating redundant structural layers.
Solution Approach 2:
The guide structure is designed with multi-functionality to serve both OIS-x-axis and OIS-y-axis driving requirements. The guide grooves and protrusions are configured to constrain movement in multiple directions (optical axis, x-axis, and y-axis) through a single integrated component arrangement, allowing the same structural element to perform multiple guiding functions simultaneously, thus reducing the need for separate guide structures for each axis.
3Speed
If a ball is used to guide the movement of the moving part, then linear movement is achieved, but the ball may be deviated from its original position due to external impact
Solution Approach 1:
The patent introduces a guide structure with guide grooves and guide protrusions as an intermediary mechanism between the moving part and the ball. This guide structure constrains the ball's movement to a precise linear path along the optical axis, preventing lateral deviation caused by external impacts. The guide protrusions engage with the guide grooves to maintain alignment, acting as a mediator that protects the positioning accuracy even when the ball is subjected to external forces.
4Force
If the ball is pressed through the yoke and magnet, then the ball is held in position, but a centering force is generated in the optical axis direction causing potential tilt
Solution Approach 1:
The patent extracts the ball from the electromagnetic assembly (yoke and magnet) and places it in a dedicated guide structure. This separation removes the ball from the magnetic field environment, eliminating the centering force that would otherwise be generated by magnetic attraction. The ball is now positioned solely by mechanical guidance through the guide grooves and protrusions, preventing unwanted centering effects and potential tilting of the moving part.
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 reduces current consumption, minimizes device height, enhances AF accuracy, and prevents structural deviation or damage from external impacts.
Implementation Method 1
an elastic member to prevent centering forces
Implementation Method 2
The auto focus function and hand shake correction function may be performed through electromagnetic interaction between a magnet and a coil
Implementation Method 3
an attractive force between the magnet and the yoke may be used to hold the ball between the fixed part and the moving part
Data Source
Figure 1
Figure 2
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AI summary
The present embodiment relates to a lens driving device comprising: a fixed part; a first moving part being disposed inside the fixed part; a second moving part being disposed inside the first moving part; a first driving part for moving the first moving part in an optical axis direction; a second driving part for moving the second moving part in a direction perpendicular to the optical axis direction; a plate member being disposed between the fixed part and the first moving part; a first ball part being disposed between the plate member and the first moving part; an elastic member being disposed between the fixed part and the plate member; and a second ball part being disposed between the fixed part and the first moving part, wherein the elastic member presses the second ball part to be supported by the fixed part.