Winding – tensioning – or guiding – Unwinding and rewinding a machine convertible information... – Cartridge system
Reexamination Certificate
2002-04-18
2003-08-19
Rivera, William A. (Department: 3654)
Winding, tensioning, or guiding
Unwinding and rewinding a machine convertible information...
Cartridge system
Reexamination Certificate
active
06607156
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic tape cassette that houses a coated high-recording-density magnetic recording medium. More specifically, it relates to a magnetic tape cassette that houses a magnetic recording medium for high-density recording, the magnetic recording medium comprising a lower layer and an upper layer on top thereof, the lower layer including a non-magnetic powder and a binder, and the upper layer including a ferromagnetic metal powder.
2. Description of the Related Art
In the field of broadcasting, a single-layer, coated metal tape that employs a ferromagnetic metal powder, and a multi-layer metal tape, in which the thickness of a magnetic layer is reduced so as to increase the output by simultaneously coating with a non-magnetic layer, have been used. Because of the prevalence of high-quality broadcasting such as Hi-Vision broadcasting or digital terrestrial broadcasting, there is a desire for a recording medium having a higher recording density than that of conventional media. In the field of data storage also, the amount of information to be handled has rapidly increased, and a rotating head system, which has been employed in the broadcasting field, is now in demand. In this data storage field there is also a desire for a backup tape having a similar high recording density and high reliability to that in the field of broadcasting.
Under such circumstances, in order to increase the linear recording density of a recording medium, the surface of the magnetic layer has become increasingly smooth, resulting in concerns about a degradation in transport durability due to an increase in the coefficient of friction. Furthermore, if an attempt is made to increase the capacity by reducing the volume recording density, a reduction in the layer thickness of the recording medium cannot be avoided, resulting in concerns about a degradation in the durability, such as edge folding, due to a decrease in the tape strength. In other words, in order to achieve a high recording density it is essential to improve the durability.
Moreover, since the unit recording area decreases, there is a possibility that fine foreign matter on the magnetic surface, which had not previously caused a problem, might cause recording dropouts, etc. When an error such as a dropout occurs during recording in a data storage system, recording is carried out again on another area on the tape (hereinafter called a ‘retry’), thus preventing the information from being missed. When the number of retries increases due to the presence of foreign matter on the tape, the transfer rate of the system rapidly decreases.
That is to say, in both the broadcasting and data storage fields there is a demand for a magnetic tape cassette housing a magnetic recording medium having a high recording density, excellent durability and high reliability.
BRIEF SUMMARY OF THE INVENTION
The present invention has been carried out in view of the above-mentioned circumstances.
It is an object of the present invention to provide a magnetic tape cassette housing a high-recording-density magnetic recording medium having high output and an extremely small number of retries.
An aspect of the present invention relates to a 2 reel type data storage magnetic tape cassette that comprises a reel around which a magnetic recording medium is wound. The magnetic recording medium comprises a support, a non-magnetic layer comprising a non-magnetic powder and a binder on one surface of the support, a magnetic layer comprising a ferromagnetic metal powder and a binder on top of the non-magnetic layer, and a back layer comprising a carbon black powder and a binder on the other side of the support. The magnetic tape cassette further comprises a rotating guide roller made of a resin within the cassette. The rotating guide roller has a ten-point average roughness Rz of 3.0 to 4.5 &mgr;m and is in contact with the surface of the magnetic layer having a center plane average roughness SRa of 2.0 to 3.5 nm.
The above-mentioned object, other objects, features, and advantages of the invention will become clear from the following description.
REFERENCES:
patent: 5479311 (1995-12-01), Doushita et al.
patent: 5914840 (1999-06-01), Kawakami et al.
patent: 5976668 (1999-11-01), Chiba et al.
patent: 6468627 (2002-10-01), Ono et al.
Araki Hiroaki
Ichikawa Tomohiro
Murao Naoto
Fuji Photo Film Co. , Ltd.
Rivera William A.
Sughrue & Mion, PLLC
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