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FUJI ELECTRIC JOURNAL July/2004 (Vol.77-No.4)
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1. Magnetic Recording Media 2. Photoconductors |
Present Status and Future Prospects for Magnetic Recording Media
Makoto Imakawa, Kenji Ozawa
Product applications for magnetic recording media are increasing due to technical advances that enable higher densities and a shift in applications from PCs that process conventional digital data to home information appliances that process video and music data. This paper describes market trends for PCs equipped with magnetic recording media and for hard disk drives (HDDs), and also summarizes the status of development of magnetic recording media, which is a significant factor in the trends toward higher densities and smaller sizes. Areal densities of 100 Gbits/in2 are achived by 2004, and it is expected that the widespread use of perpendicular magnetic recording will lead to even larger capacities and a wider range of product applications.
Aluminum Polish Substrate
Kazuhiko Yabuki, Mitsuo Masuda
As the capacity of magnetic recording media increases, aluminum substrates are being required to provide higher levels of surface cleanliness and smoothness. This paper summarizes recent developments concerning these two topics. The development of polishing agents offers promise for improving the surface cleanliness and throughput. Through collaborative development with pad suppliers, optimization of important characteristics, and advances in pad manufacturing technology, substrate surface characteristics have been improved dramatically, leading to improved head flying performance.
Longitudinal Al Substrate Magnetic Recording Media
Shoji Sakaguchi, Kazuo Nimura, Yoshiharu Kashiwakura
Longitudinal Al substrate magnetic recording media is used mainly in PCs and servers. The recording capacity of a single 3.5-inch disk exceeds 80GB. This high recording capacity is supported by substrate surface fine processing technology for controlling the shape of a substrate surface with subnanometer precision, magnetic recording layer fabrication technology for controlling the growth of crystalline structures at the nanometer level, and media surface control technology for ensuring flying stability of the magnetic head that glides above the magnetic recording media at height of only approximately 10nm. The rate of technical innovation is extremely brisk and present development efforts are aimed at achieving capacities of 160 to 200GB/disk.
Glass Substrate Magnetic Recording Media
Souta Matsuo, Katsuya Masuda, Shinji Shirai
Glass substrate magnetic recording media is used chiefly in notebook computers and in non-PC applications. With its characteristics of a hard surface and good shock resistance, glass substrate magnetic recording media is expected to be used in small form factor HDDs for mobiles
a market for which future growth is promising.
Fuji Electric
has utilized anisotropic media to achieve a better signal-to-noise ratio
(SNR) than conventional glass substrate recording media. In order to
realize this media, the glass substrate is textured directly and a proprietary
technique developed by Fuji Electric is used to deposit a seed
layer on the glass substrate. Moreover, patented technology was utilized
in the design of the head-disk interface (HDI), and this distinctive
design, unavailable from other companies, is highly regarded by our
customers.
Granular-type Perpendicular Magnetic Recording Media
Hiroyuki Uwazumi, Tatsumi Kawata, Teruhisa Yokosawa
In order to realize the practical application of perpendicular magnetic recording media having higher density than conventional longitudinal magnetic recording media, it is necessary to develop a low-noise, thermally stable magnetic layer and a thick soft magnetic underlayer, which is characteristic of perpendicular magnetic recording media. Targeting the practical application of a low-temperature-deposited granular-type magnetic recording layer to which SiO2 has been added and an electroless plated NiP soft magnetic underlayer, Fuji Electric is presently working to develop and commercialize perpendicular magnetic recording media having 120 to 160 Gbits/in2 or higher densities. This paper reports the results of these development efforts.
Perpendicular Magnetic Recording Media Technology and the Challenge to Achieve 400 Gbits/in2
Yasuyuki Kawada, Tadaaki Oikawa
Perpendicular magnetic recording media holds promise as a nextgeneration high-density media, but in order to achieve even higher recording densities, the development of new magnetic recording layer structures and material technologies is necessary. This paper presents the results of research into CoPtCr-(SiO2) perpendicular magnetic recording media from the Japanese government-sponsored "IT21 Project," based at Tohoku University's Research Institute of Electrical Communication and in which Fuji Electric is a participating member, and the results of a study of perpendicular magnetic recording media configured from a Co/Pt multilayer, to which SiO2 has been added, laminated on an Ru underlayer, and also introduces Fuji Electric’s perpendicular magnetic recording media technology that aims to realize a density of 400 Gbits/in2.
Glide Height Test Technology at Low Flying Height
Kiminori Sato, Tomonori Katano
In a magnetic disk glide height (GH) test, the flying height of the GH head was less than 10nm. From measurements taken simultaneously with a laser Doppler vibrometer (LDV) and a PZT sensor, it was learned that the low-flying GH head was pitching and making contact with the disk. GH head properties of a large pitch angle and vibrational damping are effective in improving flying stability. Additionally, a new GH test method has been developed for detecting bump defects based on the impact at the time of a collision with a bump, and a 3dB improvement in the signal-to-noise ratio (SNR) was confirmed. Even in a low-flying state, this detection method is expected to be more accurate than detection based on a conventional PZT sensor.
Present Status and Future Prospects for Photoconductors
Mitsuru Narita, Tatsuo Tanaka
Advances in information technology have given rise to a rapid popularization of image input and output devices, and the trends toward digitization and colorization have progressed especially rapidly for electrophotographic copies and printers. This paper presents an overview of these market and technical trends for photoconductors, and also outlines Fuji Electric’s photoconductors that support these trends. Pageper- minute (PPM) rates of 16 to 20 for monochrome printers, 7 to 10 and 21 to 30 for color printers, and 16 to 30 for digital copiers are predicted to become the mainstream.
Organic Photoconductors for Printers
Seishi Terasaki, Yutaka Ikeda, Toshiki Obinata
With changes in the office environment, printers have come to be positioned as system output devices, and the market for high-speed, color printers is predicted to grow dramatically. Accordingly, Fuji Electric is developing and manufacturing photoconductors suitable for various user needs. This paper presents an overview and describes the characteristics of organic photoconductors for negatively charged printers.
Organic Photoconductors for Digital Plain Paper Copiers
Micho Shinozaki, Takahito Miyamoto
Growth in the copier market has shifted from analog systems to digital systems. Digitization has brought about a merging of printer and facsimile functions for low and medium-speed devices, but for highspeed devices, such as post-printing machines, higher speed and operational stability (2 to 10 times that of printers) is required. Accordingly, enhanced sensitive characteristics, operational stability, and the like are required of photoconductors. In response to various market requirements, Fuji Electric is aiming to realize high performance organic photoconductors and has prepared a wide lineup of products. This paper introduces Fuji Electric's organic photoconductors for plain paper copiers and discusses their operational stability.
Positively Charged Organic Photoconductor
Yoichi Nakamura, Shinichi Omokawa, Motohiro Takeshima
Along with the technical advances in digitization and colorization of recent years, printers, copiers, facsimile machines and other devices that use photoconductors, in both business and personal uses, are increasingly called upon to process color and high-resolution original documents and data containing greater quantities of information than in the past. Using charge transport materials and photoconductor technology based on proprietary chemical technology, Fuji Electric has developed a photoconductor suitable even for high sensitivity, high resolution and contact charging methods, as a photoconductor capable of reproducing information-rich data stably. Moreover, aiming for even higher resolution, Fuji Electric is moving forward with development of a photoconductor suitable for liquid development.
A Study of 1-dot Latent Image Potential
Kouichi Aizawa, Yoshihiro Ueno, Motohiro Takeshima
Research into increasing the image quality of printers and digital copiers, which are electrophotographic image output devices, is proceeding. Fuji Electric has developed proprietary measurement technology that enables measurement of the latent image potential. This paper describes operating principles of latent image potential evaluation equipment, the interpretation of the acquired information and its relation to photoconductive characteristics. Moreover, the correspondence between the photoconductor configuration and latent image profile, and the change in latent image profile when photoconductor characteristics are changed are discussed. Fuji Electric will contribute to the development of picture quality enhancing technology in order to achieve even higher levels of performance in the future.
