Application of herringbone pattern to a slim-type optical disk drive for the reduction of warpage and vibration of the rotating disk

A herringbone pattern is applied beneath the top cover of a slim-type optical disk drive to suppress the warpage and vibration of a rotating disk since the pattern can modify the pressure generation over the disk by changing its geometric parameters. The effect of the herringbone geometries on the pressure generation is evaluated for various geometric parameters. The flow field and the pressure distribution in the cavity are calculated by using a commercial program with the k-ε model for the turbulent computation. To confirm the numerical results, the axial vibrations of the rotating disk as well as the pressure distribution of the air gap between the disk and the top cover are measured at various points. In this study, the application of the herringbone pattern reduces the disk warpage and axial vibration by 34 and 10% at most, respectively.