Low cost and simplified continuous servo system employing single servo signal detector is pro-posed. Servo record on the media consists of two frequency components, and the higher frequency component has a different phase on the tracks by turns. Tracking error is detected from the phase difference of those two frequency components extracted from single servo detector. The system was inspected by test system having 6μ servo track pitch. In addition, magnetic recording performances of 7μ and 9μ track width for floppy disk were evaluated. As the results, 100 - 200MB capacity 3.5" floppy disk system will be realized for practical use.

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This article presents a model following control system for disk drives to achieve high-speed track access. In this kind of control system, a reference model plays an important rote to reduce access time. we propose a new reference model based on a numerical model of the VCM (voice con Motor) used as the disk drive actuator. Taking VCM actuator dynamics into account, the reference model generates a reference trajectory to make high-speed head positioning. Simuta-tion and experimental results on a typical hard disk drive indicate the validity of the proposed method.

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High track density and short access time have been achieved using H_∞ controller with sector servo system. The authors studied the difference of control performance between designed using the weighted mixed-sensitivity problem and designed using the four block problem. Moreover, by designing 2-degree-of-freedom-controller in H_2 optimal theory, fast seeking has been realized. Applying these servo system to a hard disk drive, ±0.2μm head positioning accuracy and a 2.5 ms one-track-seek time were achieved.

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Both static and dynamic analyses of a slider flying over an embossed disk with discrete data tracks and servo marks are presented. It is shown that the averaged Reynolds equation may be employed to design a reliable slider-disk interface for a grooved discrete track disk. The mechanical resonance problem associated with a slider flying over a periodic pattern of em-bossed servo segments is analyzed and resolved. It was found that there is no critical change in flying height when using an embossed discrete track disk.

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An effect of non-linear readback process of an MR head on a PRML digital magnetic recording channel was studied. Although combination of a highly sensitive MR read head and a PRML channel is promising for high areal density recording, non-linearity in the MR readback process is a critical issue for the channel in which linearity is inherently assumed. First, we theoretically analyzed the characteristics of SHD (Second Harmonic Distortion) as a figure of merit of the non-linearity. Next, the effect of non-linearity on error rates was studied by computer simulation and examined by experiments. Results show that SHD of less than -25 dB is required for the channel in order to be rid of the non-linear distortion.

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In a VCR system, a magnetic tape is vibrated by the head-impact action when magnetic heads rush into or out of a magnetic tape. As a result, jitters on reproduced pictures are gener ated by such vibrations. It is, however, difficult to evaluate and analyze the head-impact action because magnetic heads rush into and out of a magnetic tape simultaneously. By measuring the longitudinal vibration of a magnetic tape caused by a single head and synthesizing the vibration waves, the methodology has been developed to analyze the head-impact action and to estimate jitters. Using this technique, not only the head-impact action can be evaluated respectively; but also jittes can be predicted easily and precisely whatever the number of the heads the VCR has.

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On developing a portable DCC, Electrical- and Mechanical improvement were introduced in order to reinforce shockproof and rollproof realizing the portability and light weight at the same time. The control frequency range of the motor was widen especially by applying newly developed motor and servo processor, which upgraded the rollproof performance and enabled a stable tape running. Furthermore, controlling the motor rotation speed in a step was made to ensure the control signaldetection recorded on the tape in tape search mode including the accelerating and/or decreasing tape speed.

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The engineering and actual product development of super small, light weight and low-cost mechanism. Main contents of this engineering are as follows : (1) Tapepath design that saves considerable space by arranging cylinder in cassette. (2) Cancel of capstan by using Non-Tracking system and tape driving system introducing the reel driving. (3) The engineering of manual manpower loading mechanism. (4) Low-costing by simplification and reduction of parts or mechanism. (5) The engineering of low-cost. leadless and windowless φ 17 cylinder.

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Metal Evaporated (ME) tape is supposed to be a most potential recording media for the next generation of VTR. The detail characteristic of this ME tape is, however, not clear yet. Especially, the re-recording effects in overwrite recording is still unclear, and there is no beautiful explanation. In this paper, the maximum output frequency response with different direction of orientation, and overwrite recording characteristics are measured and discussed. The difference of frequency response by different orientation directions explained by a recording model. The overwrite characteristics are almost similar to the that of conventional video tape. Considering the squareness of the ME taPe, the contact printing model is applied to explain these re-recording phenomena.

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