Winding – tensioning – or guiding – Unwinding and rewinding a machine convertible information... – Cartridge system
Reexamination Certificate
2001-08-16
2004-05-04
Nguyen, John Q. (Department: 3654)
Winding, tensioning, or guiding
Unwinding and rewinding a machine convertible information...
Cartridge system
C242S610600, C360S132000
Reexamination Certificate
active
06729570
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a tape reel and a magnetic tape which are applied to a magnetic tape cassette, and more particularly to the tape reel provided with an upper and a lower flanges at an upper and a lower end of a reel hub, and the magnetic tape to be wound around the tape reel.
BACKGROUND OF THE INVENTION
Conventionally, there have been various types of magnetic tape cassettes, namely, for a video recorder, audio apparatus, computer, etc. For example, there has been a type of the magnetic tape cassette for the video recorder which includes a cassette case consisting of an upper and a lower cassette half and a pair of tape reels having a reel hub and an upper and a lower flange rotatably contained in the cassette case in a state where a magnetic tape is wound around the reel hub.
FIG. 5
shows a basic structure of the above described tape reel. As shown in the drawing, a tape reel
110
includes a reel hub
111
around which a magnetic tape
120
is wound, an upper flange
112
fixed to an upper end of the reel hub
111
, and a disc-like lower flange
113
integrally formed at a lower end of the reel hub
111
. In this example, a lower face of the upper flange
112
is tapered with respect to a plane perpendicular to an axial direction of the reel hub
111
in such a manner that a radially outer side of the lower face is inclined upward in the drawing. An upper face of the lower flange
113
is tapered in such a manner that a radially outer side of the upper face is inclined downward in the drawing.
Recently, in order to record enormous amounts of information data in a small space, according to digitalization and downsizing of magnetic recording apparatuses, an intention is to improve recording density. The magnetic tape has been made thinner for improvement of volumetric recording density, and tracks have been made narrower for improvement of planar recording density.
Recently, in order to record enormous amounts of information data in a small space, according to digitalization and downsizing of magnetic recording apparatuses, it is intended to improve recording density. The magnetic tape has been made thinner for improvement of volumetric recording density, and tracks have been made narrower for improvement of planar recording density.
However, because the magnetic tape has been made thinner, the magnetic tape has become likely to be deformed in a lateral direction. For example, there have been some cases in which the magnetic tape has deformed in a lateral direction during fast feeding or at acceleration or deceleration of the tape in a recording and reproducing apparatus, and has locally got in touch with a guide roller and so on intensively, resulting in occurrence of a curve or a weaving of the magnetic tape. In addition, there has been a tendency that due to the deformation of the magnetic tape, the lateral ends of the magnetic tape may get in touch with the lower face of the upper flange or the upper face of the lower flange to generate abrasion powder, and dropouts may be increased.
Meanwhile, as the tracks of the magnetic tape have been made narrower, a so-called linearity defect is likely to happen such that reproducing output in the deformed area of the tape may become lower than reproducing output in a rectilinear area. Therefore, even a minute deformation of the tape may result in the linearity defect. As a result, the aforesaid weaving of the magnetic tape will incur and increase the linearity defect, in other words, there will be a variation of the reproducing output.
Moreover, because the magnetic tape has become narrower, so-called irregular winding may occur in some cases, when the magnetic tape has been wound around the reel hub. Also, and as shown in
FIG. 6
, which is an enlarged perspective view of a part A of
FIG. 5
, a part of the end of the magnetic tape may jump out from a plane formed by the ends of the magnetic tape
120
. As shown in
FIG. 6
, the part
120
a
of the end of the magnetic tape that jumps out will be deformed weavingly like sea weed. In the case where the magnetic tape has deformed like sea weed, normal recording and reproduction cannot be expected. Therefore, it is extremely important to prevent such irregular winding.
Although various factors have been considered as causes of the irregular winding, it is considered that one cause is air that may enter between adjacent magnetic tapes when the magnetic tape
120
is wound around the reel hub
111
of the tape reel
110
, and the magnetic tape may be pushed upward while the air escapes. In the case of a conventional magnetic tape having a thickness of about 10 &mgr;m for example, the irregular winding has been able to be restrained by providing a groove in the reel hub
11
of the tape reel. It is considered that because the tape had a large thickness and relatively high rigidity, the magnetic tape could have been wound without involving air by such a measure.
However, as the magnetic tape has become thinner and thinner, it has become more and more difficult to restrain the irregular winding, even though the groove has been provided in the reel hub. It has been found that the irregular winding is likely to happen especially in a case where the thickness of the tape is 7 &mgr;m or less.
Meanwhile, it has been found that almost all of the abrasion powder occurring when the ends of the magnetic tape get in touch with the lower face of the upper flange and the upper face of the lower flange is powder generated through abrasion of a back layer. As shown in
FIG. 6
, the magnetic tape
120
has been heretofore in a shape of parallelogram in cross section. A magnetic recording medium having a large width will inevitably take such a shape when it has been cut by means of a rotary cutter to form the magnetic tape
120
. Accordingly, a large amount of the abrasion powder is generated from a part B where an end of the back layer has projected from ends of a magnetic layer and a nonmagnetic layer in a lateral direction of the magnetic tape.
DISCLOSURE OF THE INVENTION
The present invention has been made in view of the above described problems, and its object is to provide a magnetic tape cassette, a tape reel and a magnetic tape in which output variation or dropout can be restrained, and which can perform more accurate recording and reproduction. Particularly, an object of a first embodiment of the invention is to provide the tape reel around which the magnetic tape can be smoothly wound, in which occurrence of deformation in a lateral direction of the magnetic tape and irregular winding can be restrained, and which can perform more accurate recording and reproduction. Further, an object of a second embodiment of the invention is to provide the magnetic tape in which an amount of abrasion powder occurring when the ends of the magnetic tape get in touch with the lower face of the upper flange and the upper face of the lower flange is decreased, and which can perform more accurate recording and reproduction.
The inventors of this invention have had an intensive study and found that deformation of the magnetic tape in a lateral direction and irregular winding can be remarkably restrained by decreasing a distance between the upper flange and the lower flange in the tape reel into a determined distance. Conventionally, it has been considered that if the distance between the upper flange and the lower flange has been decreased, the magnetic tape would be unable to be smoothly wound around the tape reel. However, by setting this distance between the upper flange and the lower flange to be the determined distance taking a width of the magnetic tape into consideration, the magnetic tape can be smoothly wound around the tape reel, and the deformation of the magnetic tape in a lateral direction and occurrence of the irregular winding can be restrained.
Specifically, the first aspect of the present invention is a tape reel comprising an upper flange and a lower flange respectively provided at an upper end and a lower end of a cylindrical reel hub around which a magnetic tape is
Morita Kiyoo
Murao Naoto
Sato Makoto
Yamagishi Mitsugu
Fuji Photo Film Co. , Ltd.
Nguyen John Q.
Sughrue & Mion, PLLC
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