Hiromi Kita

Development of FDB spindle motors for HDD use

The areal recording density of an HDD has increased noticeably at a rate of 60% to 100% a year, and further increases are expected in the future. In line with this trend, increasingly exacting tolerances are required regarding off-track errors of heads. Ball bearings have been conventionally used in spindle motors. However, off-track errors caused by non-repeatable run outs (NRRO) are approaching the control limit. Expectations for the implementation of spindle motors incorporating fluid dynamic bearings (FDBs) are rising. In this paper, we discuss FDB spindle motors, which are thought of as the future mainstream of HDD.

Finite element analysis of the interface phenomena between VCR tape and head

The authors have developed a computational method for simulating the behaviour of a tape running along a rotating cylinder with a video head fixed to it. The flexible tape is modeled as a thin anisotropic shell and the air-film is treated by the modified Reynolds equation. The two sets of equations are coupled in the finite element method. The calculated results were in good agreement with experimental ones, within an error of 7%. It is concluded that this simulation method will provide good information for optimizing head geometry and tape components. >

A new scheme for finite element analysis of an interface phenomena of VCR drum, head and tape

A numerical scheme for the finite element method (FEM) used for calculating the mechanical interface phenomena in a video cassette recorder (VCR), namely, between the tape, the head and the drum, is presented. To permit estimation of the characteristics of the VCR system and the effects of design parameters on the performance, it was necessary to reduce CPU time and memory storage without losing accuracy. The analysis area was divided into two subareas, a whole drum area and a head circumference area. The analysis for the latter area was carried out based on the results for the former area. The analysis results were in good agreement with experimental data and required a short computation time. >

Effect of mechanical anisotropy of flexible media on reproduced output

Abstract The realization of excellent head-to-tape interface is important to achieve high recording density in VCRs. Especially, the anisotropy of mechanical characteristics of the magnetic tape influences the head-to-tape contact. In the present study, we have measured the anisotropy of Youngs modulus of magnetic tapes by measuring the ultrasonic propagation velocity. The anisotropy of the particulate medium differed from that of evaporated medium. We have made a computational calculation, by the Finite Element Method, of the deformation of the tapes having anisotropy of mechanical characteristics and sliding over a head fixed on a rotating drum. The flexible tape is modelled as a thin anisotropic shell and the air film is treated by the modified Reynolds equation. The lateral tape deformation affects the reproduced output.

Finite-Element Analysis of Tape-Head Interface Phenomena of VCR.

A new numerical scheme for the finite element method for calculating the interface phenomena of VCR, namely, between the magnetic tape and the magnetic head of the drum, is presented. To enable estimation of the characteristics of the designed VCR system and the effects of design parameters on the performance, it is absolutely necessary to reduce the CPU time and the memory storage without losing accuracy. We divide the analysis area concerned into two subareas, a whole drum area and a head circumference area. The analysis is carried out in one after another, and the result is used for the other analysis. The analysis results are in good agreement with the experimental one. Moreover, the CPU time required to carry out the analysis is short.

Piezoelectric thin film reliability for HDD dual-stage actuator

Summary form only given. A new dual-stage actuator for positioning a magnetic head for high-density hard disk drives (HDDs) was proposed and developed. This dual-stage actuator device is characterized by the sputter-deposited thin film PZT, featuring large displacement of 1.2 microns and high resonance frequency over 15 kHz. In this work, reliability against temperature, humidity, heat cycle, and mechanical shock was investigated to ensure the practical application to the drive products.

Computer Mechanics. Analysis of Tape Floating Characteristics of VCR Considering Fluid Viscosity and Contact Friction.

The friction between the magnetic tape and the drums causes many problems in a VCR. In our previous paper we presented a numerical method to analyze the interface phenomena between magnetic tape and the magnetic head or drums in a VCR. In this study we calculated the tape floating characteristics on an entire drum in an actual VCR, considering the contact friction and fluid viscosity. We obtained the dependence of tape floating characteristics on the friction between the magnetic tape and the drums. The calculated results showed good agreement with the experimental results.

Analysis of Tape Floating Behaviour in VCR using Averaged Thickness Method.

The floating phenomena of the tape on the rotating drum in VCRs were treated as an air-bearing problem using the averaged thickness theory coupled with a tape deformation problem of an anisotropic thin shell equation in FEM (Finite Element Method). We obtained the floating height distribution dependence on the groove structure of the drum by computational simulation. We compared the averaged thickness model and the exact node model. We showed that the square grooves are more effective than the triangular grooves. Good agreement between the calculated and the measured results on the tape floating behaviour has been obtained. We showed the effectiveness of the structure/fluid coupled analysis using the averaged thickness theory. The computational simulation is very useful for designing the new VCR systems and determining the effects of design parameters.

FEM Analysis Of The Interface Phenomena Of VCR Tape And Head

Characteristics of performance of VCR is quite dependent on the phenomena occurring at `the interface (air film pressure on the head and tape deflection along the head) between magnetic tape and head. Since it is very difficult to measure experimentally the air-film pressure at the interface and deflection of the medium, an accurate computer simulations of great importance. We developed the computational method for simulating the behavior of a tape running along a rotating cylinder with a video head fixed to it. The flexible tape is modeled by a thin anisotropic shell and the air-film is treated by the modified Reynolds equation. The two sets of equation are coupled together in the FEM( Finite Element Method). The calculation result show a good agreement with experimental ones within an error of 7 %.