Curved Spring Actuator for Optical Pick-Up
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Solution Overview
Problem
The miniaturization of optical pick-up devices is hindered by the size of the actuator, which must maintain focus and track on optical disks while resisting external impacts, and existing designs face challenges in reducing thickness without causing unwanted lens rotation or vibration, leading to errors in optical signal reading.
Innovation Solution
An actuator design featuring two fixing frames, a lens holder with focus and tracking coils, and springs with bends to support the lens holder, utilizing a permanent magnet and yoke to generate a magnetic field, allowing for precise movement in focusing and tracking directions while minimizing thickness and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the actuator uses a conventional design with straight springs and standard magnetic field generation, then the structure is simple and easy to manufacture, but the thickness cannot be reduced without causing lens rotation or vibration
Solution Approach 1:
The spring is designed with a curved configuration instead of a straight structure. The curvature of the spring allows it to provide the necessary mechanical support and magnetic field generation within a reduced thickness, while the curved geometry helps maintain structural integrity and prevent lens holder rotation or vibration during operation.
Solution Approach 2:
The actuator employs composite material construction, particularly in the spring structure and magnetic field generation components. This allows for optimized material properties that enable thinner overall dimensions while maintaining the necessary mechanical strength, magnetic field uniformity, and vibration resistance required for reliable lens holder positioning.
2Volume of moving object
If the actuator is miniaturized to reduce device size, then the optical pick-up device can be applied to mobile devices, but the precision of focus and tracking movement is compromised
Solution Approach 1:
The spring's physical parameters, including its curvature radius, thickness, width, and material properties, are precisely optimized to achieve the desired balance between miniaturization and precision. By carefully adjusting these parameters, the spring provides accurate focus and tracking movement control within a compact form factor suitable for mobile devices.
Solution Approach 2:
The actuator replaces conventional mechanical positioning systems with an electromagnetic drive system using the spring structure and permanent magnet. This substitution enables more precise control of the lens holder's movement in focus and tracking directions while achieving miniaturization, as electromagnetic actuation offers superior position control compared to traditional mechanical linkages.
3Length of moving object
If the spring is made thinner to reduce actuator thickness, then the device can be miniaturized, but the spring's elastic properties and support capability are reduced
Solution Approach 1:
The spring utilizes a curved configuration that optimizes its structural efficiency. The curvature allows the thinner spring to maintain higher bending stiffness and better load-bearing capacity, as curved beams exhibit improved mechanical properties compared to straight beams of the same thickness. This enables the spring to provide adequate support capability while achieving miniaturization.
Solution Approach 2:
The spring is constructed using composite materials that combine high strength-to-weight ratio and excellent elastic properties. This allows the spring to be made thinner while maintaining or even improving its support capability, as the composite material structure provides enhanced strength and flexibility characteristics that conventional homogeneous materials cannot achieve at reduced thicknesses.
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 actuator effectively reduces the size and weight of the optical pick-up device, enhances movement precision, and reduces the required electromotive force, minimizing lens holder inclination and vibration, thus improving data reading accuracy and reducing the actuator's size and weight.
Implementation Method 1
a permanent magnet 113 generating a magnetic field, a yoke 112 forming a path of the magnetic field
Implementation Method 2
The movable part has a coil cooperating with a permanent magnet 43 provided on the stationary part to locate the focus lens 49 to the desired position
Implementation Method 3
springs supporting the lens holder, the springs connecting two points of each fixing frame to the lens holder, each spring having one or more bends
Data Source
AI summary
An actuator of an optical pick-up device includes two fixing frames, a lens holder disposed between the fixing frames and provided with a focus lens and coils, springs supporting the lens holder, the springs connecting two points of each fixing frame to the lens holder, each spring having one or more bends, a permanent magnet disposed facing the coils to generate magnetic field, and a yoke forming a path of the magnetic field generated by the permanent magnet.