Lens Holder Driving Device with Surface Texture to Reduce Static Adhesion
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Solution Overview
Problem
The existing autofocus lens holder driving devices for compact cameras suffer from malfunctions where the lens holder becomes stuck to the inner wall of the outer yoke due to static electricity, leading to a reduced linear range and lost margin in the maximum stroke, causing non-linearity in the driving response.
Innovation Solution
A lens holder driving device with a contact area reduction arrangement, where the upper surface of the lens holder's protrusion portions feature formed grain or wrinkles to reduce static attraction, and optionally using a conductive material in the lens holder to dissipate static electricity, ensuring a wider linear range and maintaining the maximum stroke margin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the lens holder moves upward along the optical axis by flowing current through the driving coil, then the lens holder can achieve focus adjustment from infinity to macro position, but the lens holder becomes stuck to the inner wall of the outer yoke due to static electricity in the vicinity of maximum stroke, reducing linear range and causing non-linearity
Solution Approach 1:
The patent changes the surface properties of the lens holder by forming grain or wrinkles on its upper surface, which alters the static electricity characteristics and reduces adhesion to the outer yoke. This parameter change in surface texture resolves the sticking issue while maintaining the full focus adjustment range from infinity to macro position.
Solution Approach 2:
The patent converts the harmful static electricity effect into a beneficial design feature by intentionally forming grain or wrinkles on the lens holder surface. These surface features, which normally might be considered defects, are instead used to control and reduce static adhesion, transforming a harmful physical phenomenon into a useful design element that prevents sticking.
2Length of moving object
If the upper end portion of the lens holder makes contact with the inner wall surface of the ring-shaped end portion of the outer yoke, then the maximum stroke is achieved for macro position, but static electricity causes the lens holder to be sucked to the inner wall surface, reducing the margin in maximum stroke
Solution Approach 1:
The patent modifies the surface parameters of the lens holder by forming grain or wrinkles on the upper surface, which changes the static electricity characteristics. This parameter change reduces the adhesion force between the lens holder and outer yoke, ensuring that the lens holder can achieve the full maximum stroke margin without being sucked to the inner wall surface.
3Ease of manufacture
If the lens holder is made of plastic molded parts, then the device is easy to manufacture and miniaturized, but static electricity accumulates on the plastic surface causing adhesion to the outer yoke
Solution Approach 1:
The patent changes the surface parameters of the plastic molded lens holder by forming grain or wrinkles on the upper surface. This parameter change in surface texture modifies the static electricity characteristics of the plastic material, reducing adhesion to the outer yoke while maintaining the ease of manufacture through molding processes.
Solution Approach 2:
The patent creates a composite surface structure by combining the plastic molded material with surface-grained or wrinkled features. This composite approach integrates the manufacturing advantages of plastic molding with the static electricity control benefits of textured surfaces, resolving the contradiction between ease of manufacture and harmful static accumulation.
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
The solution ensures linearity in the driving response and maintains the maximum stroke margin by reducing static attraction between the lens holder and the outer yoke, preventing sticking issues and enhancing the overall performance of the autofocus mechanism.
Implementation Method 1
a lens holder driving device which moves a lens holder in a direction of an optical axis by flowing a current through a driving coil
Implementation Method 2
an elastic member (an upper elastic member and a lower elastic member) for supporting the lens holder in a direction of an optical axis of the lens assembly shiftably
Implementation Method 3
a permanent magnet opposite to the driving coil
Data Source
AI summary
A lens holder driving device includes a lens holder in which a lens assembly is mounted, a driving coil fixed to the lens holder at outside circumference thereof, an outer yoke including an outer hollow cylindrical portion and an ring-shaped end portion disposed an upper end of the outer hollow cylindrical portion, a magnet disposed to an inner wall surface of the outer hollow cylindrical portion so as to be opposite to the driving coil, an elastic member supporting the lens holder in a direction of an optical axis shiftably, and a base disposed at a lower side of the lens holder. The lens holder driving device includes a contact area reduction arrangement reducing a contact area between the ring-shaped end portion of the outer yoke and an upper end portion of the lens holder.