Jinmoo Park

An Optical Flying Head Assembly for a Small-Form-Factor Plastic Disk in PCMCIA-Like Drive

In a small-form-factor (SFF) optical disk drive (ODD), the optical flying head (OFH) on a thin-cover-layered plastic disk requires not only uniformity of the cover layer thickness of the disk media, but also the flying stability of OFH on the plastic disk surface with low flying height variation, as well as precise tolerance management in the OFH assembly. Therefore, in order to develop a practical optical pickup head interfaced to the plastic disk, we designed the OFH with a parallel-plate electrostatic actuator for the vertical positioning of the objective lens for better flying characteristics. The flying height of the OFH is designed to be 200 nm to increase air-bearing stiffness. On the other hand, a UV resin cover layer is adopted as a protective layer and a hard and stiff plastic substrate is also adopted to increase the durability of the disk. In the evaluation of the stability of the OFH and the durability of the disk, we introduce computational and experimental results on the flying height variation of the OFH, additionally we investigated the characteristics of the durability of various plastic disks.

Effective Design and Performance of an Optical Flying Head for Near-Field Recording

We studied the effective design of a head structure to realize a practical optical flying head (OFH) for near-field recording (NFR) with both high optical performance and reasonable tolerance in assembly. In the design of the OFH, several major issues such as productivity, performance and reliability were considered. In order to realize a stable and reliable OFH with high performance, we designed a slider structure, air bearing surface (ABS), coil for magneto optical (MO) recording, main optical pickup unit (OPU), suspension and gimbal structure, disk media for good head-disk interface, and so forth. With a view to the reliability of OFH, durability and flying stability for various plastic disks as well as on a conventional glass disk were investigated. Also with a view to the practical applicability, we proposed two OFH designs with simple and effective slider structures, namely a slot slider and a barrel slider. In addition, basic flying characteristics and optical performance of the OFH mounted with high NA optics were tested and evaluated. Attempts have been made to develop engineering plastic and polycarbonate disks as well as glass as disk media for NFR application. The durability of developed disks was examined and compared with the aim of their practical application.

PCMCIA-like ultrasmall form-factor optical drive

A prototype of ultra small optical drive was studied and developed in order to see the feasibility of mobile application, which is targeted to be attachable into the PCMCIA II slot in small mobile devices. A new design and fabrication technology of optical flying head (OFH) for first surface MO recording was studied, and an effective OFH precisely equipped with high NA lens and MO coil was developed based on miniaturization technology. Design consideration of small form factor optical drive is discussed. Some technical issues and barriers in designing and manufacturing the OFH are introduced. Head-disk interface for reliability and flying stability on plastic disk media was tested and evaluated. Basic tracking and read-write performances in a test bed system were tested.

Design and Fabrication Technology of Optical Flying Head for First Surface Magneto-Optical Recording

The optical flying head (OFH) was designed and fabricated for implementation of the first surface magneto-optical (MO) recording technology. The OFH structure for integration with the small ball lens and double-layer microcoil has been developed. An objective lens and microcoil thinned by 30 µm were attached to the OFH. It was found that the OFH could fly above the disk media at a more than 100 nm flying height with a 2 µm lens bottom-to-disk cover layer gap; and the microcoil had a 20 Ω resistance and 160 nH inductance as measured up to 100 MHz. The performances of the OFH and microcoil were adequate to demonstrate the feasibility of the magnetic field modulation (MFM) MO recording technology.

Airflow Analysis in a Near Field Optical Disc System

Flow fields in a near field recording system were analyzed using computational fluid dynamics (CFD). Numerical conditions were reviewed in detail. A robust head design against dust contamination was suggested by a parametric study.