Vibration and noise reduction of an optical disk drive by using a vibration absorber

Vibration and noise reduction of an optical disk drive by using a vibration absorber is presented in this paper. In optical disk drives such as CD-ROM or DVD drives, vibration may become one of serious problems to be resolved as the rotating speed and the storage capacity increase. It is practically difficult to overcome the off-track and off-focusing errors by only the servo control without reducing vibration. In particular, when an optical disk drive has a wavy spinning disk, it may suffer from severe vibration. Based on the vibration signals measured by a laser vibrometer and an accelerometer, the resonance frequency of the disk drive is identified. For reduction of the vibration around the resonance frequency, a vibration absorber is designed and it is equipped on the feeding deck of the drive. The proposed vibration absorber consists of a steel plate ring and a rubber bobbin, which play roles of inertia mass and a spring, respectively. During the design procedure of the absorber, a finite element model is used to determine the required fundamental natural frequency of the absorber. The test results of vibration and noise after being equipped with the absorber show that vibration and noise of the optical disk drive are considerably reduced.

I. Introduction

Optical disk drives such as CD-ROM and DVD drives are widely used to store text, audio, image or video data. Minimization of the off-tracking and off-focusing errors in writing and reading data is a main issue when developing disk drives, because these errors are directly connected to the reliability of the drives. The off-tracking and off-focusing errors can be reduced by the servo control when vibration level of an optical disk drive is relatively low. However, if excessive vibration occurs, it is practically impossible to overcome the errors by using only the servo control without reducing vibration. Particularly, when a ‘wavy’ disk is spinning on an optical disk drive, severe vibration may be observed and the errors cannot be avoided at a certain rotating speed. The wavy disk in this paper represents a deformed or bent disk. A normal disk is easily deformed to a wavy disk by careless use, for instance, application of heat or an external force to the disk.