Lens Frame Coil Integration for Optical Pickup Warpage
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Solution Overview
Problem
Slim-type optical disc drives face structural unsoundness due to the use of light plastic for the lens frame, which warps under electromagnetic forces, leading to tracking and focusing delays.
Innovation Solution
A lens driving unit with a lens frame having four side surfaces and an object lens on top, featuring pairs of first and second driving coils wound around specific side surfaces, supported by suspension wires and a yoke with magnets, where the coils are integrally formed within the frame, ensuring surface symmetry to prevent warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a light plastic lens frame is used to reduce weight, then the weight is reduced, but the structural strength and stability deteriorate, causing warpage under electromagnetic forces
Solution Approach 1:
The patent uses a plastic lens frame with integrated coil winding units, creating a composite structure that combines the lightweight advantage of plastic with the structural reinforcement of embedded coils. This composite approach maintains low weight while improving resistance to electromagnetic forces through the integrated coil structure.
2Power
If driving coils are wound around diagonally opposite side surfaces, then the electromagnetic driving function is achieved, but the lens frame experiences concentrated forces causing warpage
Solution Approach 1:
The patent positions the first and second driving coils on adjacent side surfaces rather than diagonally opposite surfaces, creating an asymmetric force distribution pattern. This asymmetric arrangement prevents concentrated forces from acting on diagonal sections of the lens frame, thereby reducing warpage while maintaining the electromagnetic driving function.
3Volume of moving object
If the optical pickup is designed for slim-type drives with limited thickness, then the device size is reduced, but the available weight and parts are limited, resulting in low structural strength
Solution Approach 1:
The patent merges the lens frame structure with integrated coil winding units, combining multiple functional elements into a unified structure. This merging allows the slim optical pickup to achieve adequate structural strength through the integrated coil-frame composite without increasing overall thickness or requiring additional separate components.
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 configuration enhances the structural integrity and stability of the lens frame, reducing warpage and improving frequency response characteristics, thus preventing tracking and focusing delays, while maintaining a slim form factor.
Implementation Method 1
a pair of first driving coils that are wound around a first side surface of the lens frame, a pair of second driving coils that are wound around a third side surface facing the first side surface of the lens frame
Implementation Method 2
a yoke comprising a plurality of magnets fixed thereto which correspond to the first and second driving coils
Data Source
AI summary
Provided is a lens driving unit for an optical pickup and an optical disc drive employing the lens driving unit. First and second driving coils are directly wound around a coil winding unit included in the lens frame, which is different from a conventional lens frame in which a driving coil is manufactured as a separate element and is separately attached to a lens frame.