Yoshiaki Mizoh

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. >

P‐206L: Late‐News Poster: Low Electric Consumption 3.6W Green SHG Laser Light Source Applicable to Laser Projection Systems

Highly-efficient fully air-cooled green laser light source with frequency doubling module is reported. As a result, 3.6 watts green laser light generation with about 9% wall-plug efficiency is achieved. By using fully air-cooled RGB lasers including the green SHG (Second Harmonic Generation) laser and illumination optics for speckle noise reduction, a laser projection engine is prototyped. A laser rear-projection system with this laser projection engine shows several merits; wide color gamut (133%NTSC), 61inch large screen size, and low electric power consumption (less than 100W, at 650cd/m2).

Experimental Study on Flow-Induced Disk Flutter Dynamics by Measuring the Pressure Between Disks

It is important to clarify the characteristics of flow-induced vibrations in hard disk drives in order to achieve an ultrahigh magnetic recording density. In particular, it is necessary to reduce the flow-induced disk vibrations referred to as disk flutter. This paper describes the correlation between the disk vibration amplitude and the pressure fluctuation between a pair of high-speed corotating disks. It also reveals the effects of the arm thickness and arm shape on the disk vibrations and the static pressure between the disks. The disk vibrations were measured using a laser Doppler vibrometer (LDV). The static pressure downstream of the arm between a pair of narrow disks was measured by a method in which a side-hole needle was used as a measurement probe. In addition, the direction of air flow along the trailing edge of the arm was measured using a hot-wire anemometer. The experimental results revealed that the arm inserted between the disks suppresses the disk vibrations. However, the shape and thickness of the arm did not quantitatively affect the disk vibrations. The root-mean-square (RMS) static pressure fluctuation downstream of the arm decreased remarkably, whereas the mean static pressure increased when the arm was inserted between the disks. Furthermore, the circumferential variations in both the RMS and mean static pressures reduced when the arm was inserted. Therefore, it is suggested that the disk vibrations are excited by an increase in the static pressure fluctuation, mean dynamic pressure, and circumferential variation in the static pressure between the disks. Consequently, the disk vibrations can be suppressed by inserting the arm or a spoiler.

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.

Effect of Residual Stress on the Recording Characteristics of a Magnetic Head.

We propose a system for analyzing the magnetic field of a magnetic head, taking account of the residual stress distribution. This simulation system is composed of three analytic parts: a thermal stress distribution analysis part, a permeability distribution analysis part and a magnetic field analysis part. The system was applied to ametal-in-gap-type magnetic head in order to investigate the effect of residual stress on the recording characteristics. We assumed that the stress was caused by the difference in the thermal expansion coefficients of the constituent materials. The permeability reaches a maximum for an optimum combination of thermal expansion coefficients, which are different for ferrite, thin magnetic metal film and bonding glass. The calculated output agrees well with the measured output. Use of the system optimizes the magnetic head in terms of the residual stress.

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 %.