Lens Actuator Ball Guide Layout for Linear Autofocus and OIS
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Solution Overview
Problem
Conventional lens actuators face issues such as increased current consumption due to heavier magnets, increased height in the optical axis direction, and lack of linearity in current and travel distance for autofocus and handshake correction functions.
Innovation Solution
A lens actuator design that places a lighter coil in the moving unit, integrates guide structures for OIS-x and OIS-y-axis driving, and uses a coil spring to eliminate centering forces and improve linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a magnet is disposed in the moving unit and a coil is disposed in the fixed unit, then the autofocus function can be performed, but the current consumption increases due to the heavier weight of the magnet compared to the coil
Solution Approach 1:
The patent inverts the conventional arrangement by placing the coil in the moving unit and the magnet in the fixed unit. This reversal reduces current consumption because the coil is lighter than the magnet, allowing the moving unit to be driven more efficiently while maintaining the electromagnetic interaction necessary for autofocus operation.
2Reliability
If guide structures for OIS-x-axis driving and OIS-y-axis driving are disposed in separate layers, then the handshake correction function can be performed, 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. This combination allows both orthogonal方向的 stabilization movements to be achieved within the same spatial layer, eliminating the need for separate layers and thereby reducing the overall height of the camera device in the optical axis direction.
3Manufacturing precision
If a ball is held between the fixed unit and the moving unit through the attractive force between the magnet and the yoke, then the lens movement along the optical axis can be guided, but a centering force exists in the direction of the optical axis
Solution Approach 1:
The patent extracts the centering force issue by using a spring-loaded ball mechanism instead of magnetic attraction. The spring applies a constant outward force on the ball, counterbalancing any centering forces that might arise during lens movement, thereby eliminating the unwanted optical axis centering effect while maintaining precise positioning guidance.
4Ease of operation
If the conventional drive structure is used for handshake correction function, then the lens can be moved, but linearity between current and travel distance is not secured over the entire stroke range
Solution Approach 1:
The patent improves linearity by changing the mechanical parameters of the drive system, specifically using a optimized ball guide structure and spring mechanism that maintain consistent force distribution across the entire stroke range. This ensures a linear relationship between the applied current and the resulting lens travel distance, enhancing positioning precision throughout the full range of motion.
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
Reduces current consumption, minimizes height, enhances accuracy, and ensures linearity over the entire stroke range for autofocus and handshake correction functions.
Implementation Method 1
a coil spring coupled with the bobbin and the housing, wherein the coil spring is configured to press the second ball
Implementation Method 2
The autofocus function and the handshake correction function may be performed through electromagnetic interaction between the magnet and the coil
Data Source
Figure 1
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Figure 4~5
AI summary
A first embodiment of the present invention relates to a lens actuator comprising: a base; a housing disposed on the base; a bobbin disposed inside the housing; a first ball disposed between the housing and the base; a second ball disposed between the housing and the lower side of the bobbin; and a coil spring coupled to the bobbin and the housing, wherein the coil spring pressurizes the second ball.