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Article type: Cover
1995 Volume 19 Issue 39 Pages
Cover1-
Published: August 25, 1995
Released on J-STAGE: October 13, 2017
RESEARCH REPORT / TECHNICAL REPORT
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Article type: Index
1995 Volume 19 Issue 39 Pages
Toc1-
Published: August 25, 1995
Released on J-STAGE: October 13, 2017
RESEARCH REPORT / TECHNICAL REPORT
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Hisao Kinjo, Hiromichi Hirayama, Ryo Nishima, Naoyuki Nakagawa, Morio ...
Article type: Article
1995 Volume 19 Issue 39 Pages
1-7
Published: August 25, 1995
Released on J-STAGE: October 13, 2017
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It has been generally believed that the drum, the core mechanical part of the VCR, should be firmly fixed. In an attempt to change the established drum structure, the authors have developed a new VHS VCR which employs the Dynamic Drum (DD) system. The DD system realizes noise-free pictures at any playback speed. The following three features are built into the DD system. (1) The tape lead is separated from the lower drum but combined precisely with the lower drum coaxially. (2) The head drum is compensated to trace any tracks. The lead is compensated to obtain a smooth tape run. (3) In recording, two sets of fulcrums keep the standard position of the drum.
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Naoto Hirohata, Yoshio Mizuno, Katsuyuki Shudo, Shigeru Kawase, Yoshio ...
Article type: Article
1995 Volume 19 Issue 39 Pages
9-14
Published: August 25, 1995
Released on J-STAGE: October 13, 2017
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The paper describes a new control system for VCR drums. The system, Dynamic Drum system, has the drum assembly's rotation axis tilted to accurately trace recording tracks for noise-free playback. The tilt angle for each playback speed is coarsely controlled by a rotary encoder ; the tilt angle is finely controlled by a detected envelope of playback signals. The 2-step control of DD enables fast angle determination and high stability even for video-tapes recorded on other VCRs. The data for the optimum tilt angle at each playback speed can be saved for coarse tilt angle control.
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Hiroya Abe, Kouji Minabe, Hideo Nishijima, Kouji Kaniwa, Yoshio Narita
Article type: Article
1995 Volume 19 Issue 39 Pages
15-21
Published: August 25, 1995
Released on J-STAGE: October 13, 2017
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In order to reduce the cost and size of circuits of VCR, a new tracking control method and a new phase detection method of cylinder using playback signal have been developed. The developed tracking control system uses mountain climbing method by detecting the playback signal level. The mountain climbing method was realized by development of speed compensation control and dynamic mode control. The developed cylinder phase detection method was realized by analysis of shape of playback signal. Those developed method made it possible to reduce the circuits for special signals, so large reduction has been realized.
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Toshihide Hamaguchi, Masahiro Moriyama, Kouichi Kawakami, Noriaki Kita ...
Article type: Article
1995 Volume 19 Issue 39 Pages
23-29
Published: August 25, 1995
Released on J-STAGE: October 13, 2017
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CCTV systems are being increasingly used for many applications, Time Lapse VCR which can record realtime video for long periods is in great request. We have developed a VCR which allows 24-hour continuous video and audio recording at 20 fields per second on a single cassette tape (T-160). This 24-hour real time VCR has been achieved by using a "noiseless" head change method to playback video and audio clearly and continuously, and high accuracy technologies such as field advance control which work well with 19.3μm narrow track pitch. Thus, this system allows playback and analysis of video containing rapid motion.
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Koji Saito, Naoki Honda, Goro Obinata, Kazuhiro Ouchi
Article type: Article
1995 Volume 19 Issue 39 Pages
31-38
Published: August 25, 1995
Released on J-STAGE: October 13, 2017
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In order to increase magnetic recording density, track width and head-medium spacing have been decreasing. A contact head system is newly under developing for obtaining the smallest lest spacing. Friction force may bring same fatal problems in this case such that friction would deteriorate servo accuracy and stability. Linear control system is fundamentally not able to compensate friction force so that a quasistatic position error would remain due to the nonlinear dynamics. A dither signal is injected to manipulating signal for linearizing the nonlinearity. The dither signal design and modification of manipulating signal for magnetic bead servo system were studied by a computer simulation. The quasi-static position error was tremendously reduced by using the optimized dither signal.
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Jun ISHIKAWA, Yoshiho YANAGITA, Toshiro HATTORI, Masanobu HASHIMOTO
Article type: Article
1995 Volume 19 Issue 39 Pages
39-46
Published: August 25, 1995
Released on J-STAGE: October 13, 2017
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To enhance formatting efficiency of high density disk drives, the number of embedded servo signals has to be decreased. In this lower sampling rate of the servo system, it is difficult to attain fast track seek by using only a feedback controller. To solve this problem, two degree-of-freedom (2DOF) control, which simultaneously uses feedback and feed-forward control, has been applied to HDD systems. In a 2DOF control system, designing the reference model well can improve the response performance of the lower sampling rate system. This paper presents a 2DOF control system to effectively use a voice coil motor (VCM) through a new reference model, which generates reference trajectories allowing high-speed moving. Experimental results using a typical hard disk drive indicated the validity of the proposed method, especially for short stroke seeks.
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Ryuichi Yoshiyama, Yuzo Seo, Toshihiko Kuriyama, Yoji Arita
Article type: Article
1995 Volume 19 Issue 39 Pages
47-52
Published: August 25, 1995
Released on J-STAGE: October 13, 2017
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A floppy disk drive employing simplified continuous servo system with optical servo signal detector was developed. The servo detector consists of a couple of laser and photo diodes, and both of them are built in upper and lower conventional transducing heads, respectively. Trenches to prevent head floating from media surface were introduced at the slider surface. This enabled good read/write characteristics at the spindle rotational speed up to 2500 rpm. Barium ferrite media having dye layer between laminated base films was also developed and servo signal was written on the dye layer by using 830 nm laser beam. Using the barium ferrite of 1250 Oe coercive force and MIG head, 45 kFRPI D_<50> of the linear density was obtained. From these results, 128 MB large capacity of 3.5 inch floppy disk will be expected to realize for practical use.
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K. Nakamura, T. Utakouji, N. Watanabe, M. Yabe, M. Shinoda, K. Kime
Article type: Article
1995 Volume 19 Issue 39 Pages
53-60
Published: August 25, 1995
Released on J-STAGE: October 13, 2017
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We have newly developed the Twin Lens Optical Pick-up with the capability of playing both 0.6 mm thick DVD (complies with SD standard) and 1.2 mm disc such as CD-DA and CD-ROM. This pick-up incorporates our unique sliding and rotary type objective lens actuator, on which two objective lenses (one is for DVD and the other is for CD) are mounted. With the method to select the lens according to the disc type, the optimum beam spot is acquired in any case. A detail analysis of the focusing mechanism helped considerable reduction of the spot diameter down to 1μm or less.
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Article type: Appendix
1995 Volume 19 Issue 39 Pages
App1-
Published: August 25, 1995
Released on J-STAGE: October 13, 2017
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