Piezoelectric Actuator Optical Head for Compact Disk Drives
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Solution Overview
Problem
Existing optical disk recording/reproducing devices face challenges in achieving a thinner and lighter design due to the large diameter of DC motors used for spherical aberration correction, which leads to heat dissipation issues and increased risk of motor failure, especially in compact devices like notebook computers, and also struggle with foreign matter such as dust affecting the optical components.
Innovation Solution
The optical head and recording/reproducing device incorporate a drive member with a rotor and stator where at least part of the stator is exposed, allowing for efficient heat release through air flow induced by the rotating optical disk and preventing foreign matter from adhering to the optical components by directing it away from the disk path, thereby enabling a more compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a DC motor is used to drive the collimator lens for spherical aberration correction, then the lens can be moved accurately, but the device becomes thicker and heat dissipation becomes problematic
Solution Approach 1:
The patent replaces the conventional DC motor with a piezoelectric actuator that uses piezoelectric expansion/contraction to drive the collimator lens. This substitution eliminates the need for a large motor while maintaining positioning accuracy, thereby reducing device thickness and improving heat dissipation.
Solution Approach 2:
The patent changes the driving mechanism from electromagnetic (DC motor) to piezoelectric actuation, fundamentally altering the operational parameters and physical principles used to achieve lens movement. This parameter change enables compact design while preserving precision.
2Weight of stationary object
If the device is made thinner to reduce weight and size, then portability is improved, but heat dissipation becomes insufficient and motor reliability decreases
Solution Approach 1:
By replacing the DC motor with a piezoelectric actuator, the patent eliminates the heat generation and reliability issues associated with motors in thin devices. The piezoelectric actuator generates minimal heat and has no moving parts that can fail, ensuring reliability in compact designs.
Solution Approach 2:
The patent changes the actuation mechanism to one that operates with minimal heat generation, fundamentally altering the thermal parameters of the system. This allows the device to be made thinner without compromising reliability due to heat dissipation limitations.
3Force
If a DC motor is used for lens drive, then sufficient driving force is provided, but the large motor diameter increases device thickness
Solution Approach 1:
The patent substitutes the DC motor with a piezoelectric actuator that generates driving force through piezoelectric expansion and contraction. This mechanism provides sufficient driving force for lens movement without requiring a large diameter, thereby reducing device thickness.
Solution Approach 2:
The patent changes the force generation mechanism from electromagnetic torque to piezoelectric mechanical expansion, fundamentally altering how driving force is produced. This parameter change enables adequate force output in a compact form factor.
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 effectively dissipates heat generated by the drive member and prevents adverse effects from foreign matter, allowing for a thinner and more stable optical disk recording/reproducing device that can handle various types of optical disks without compromising performance.
Implementation Method 1
heat release through air flow induced by the rotating optical disk
Data Source
AI summary
An optical disk recording/reproducing device includes a turntable 7 configured to rotate an optical disk 9 and an optical head 3 configured to record/reproduce information in/from the optical disk 9. A stepping motor 13 to drive a collimator lens 16 is mounted on a head base 17 of the optical head 3 and a part of stator 42 of the stepping motor 13 is exposed through an opening 14a of a head cover 14, an opening 15a of a flexible substrate 15, an opening 13a of a cover 41, and an opening 13b of the cover 41.