Stock material or miscellaneous articles – Composite – Of inorganic material
Reexamination Certificate
2001-01-24
2003-09-30
Kiliman, Leszek (Department: 1773)
Stock material or miscellaneous articles
Composite
Of inorganic material
C428S690000, C428S690000, C428S900000, C427S128000, C427S129000, C427S130000, C427S131000, C083S062100, C083S436450, C083S437200, C083S503000, C083S508300, C083S698510
Reexamination Certificate
active
06627334
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a magnetic tape for recording various kinds of information. This invention also relates to a method and apparatus for slitting a magnetic tape web into magnetic tapes. This invention further relates to a method of polishing magnetic tape web slitting blades, which are utilized for slitting a magnetic tape web having a wide width into long narrow magnetic tapes.
2. Description of the Related Art
Magnetic tapes have heretofore been utilized for recording various kinds of information, such as video information and audio information. Ordinarily, the magnetic tape comprises a base layer, a back coating layer overlaid on one surface side of the base layer, and a magnetic layer overlaid on the other surface side of the base layer. The magnetic tape is moved in the longitudinal direction of the magnetic tape, while the magnetic layer of the magnetic tape is being in contact with a head of a recording and readout apparatus, and information is thereby recorded on the magnetic tape or read out from the magnetic tape.
Ordinarily, magnetic tapes are formed by slitting a magnetic tape web. For the slitting of the magnetic tape web, for example, a slitting apparatus as illustrated in
FIG. 1
, which will be described later, is utilized. As illustrated in
FIG. 1
, the slitting apparatus comprises an upper slitting blade shaft
1
and a lower slitting blade shaft
2
. A plurality of upper slitting blades
3
,
3
, . . . are fitted to the upper slitting blade shaft
1
so as to stand side by side along an axial direction, and such that cutting edges of the upper slitting blades
3
,
3
, . . . may be located at predetermined intervals. Also, a plurality of lower slitting blades
4
,
4
, . . . are fitted to the lower slitting blade shaft
2
so as to stand side by side along the axial direction, and such that cutting edges of the lower slitting blades
4
,
4
, . . . maybe located at the predetermined intervals. The upper slitting blade
3
and the lower slitting blade
4
, which stand facing each other, are located such that a cutting edge vicinity region of the upper slitting blade
3
and a cutting edge vicinity region of the lower slitting blade
4
may overlap each other in a radial direction. In the slitting apparatus, a magnetic tape web
5
having a wide width is set such that the magnetic layer may face up. Also, the magnetic tape web
5
is moved between the upper slitting blades
3
,
3
, . . . and the lower slitting blades
4
,
4
, . . . and along a direction normal to the plane of the sheet of
FIG. 1
, while the upper slitting blades
3
,
3
, . . . and the lower slitting blades
4
,
4
, . . . are being rotated respectively together with the upper slitting blade shaft
1
and the lower slitting blade shaft
2
. In this manner, the magnetic tape web
5
is slitted into a plurality of long narrow magnetic tapes
6
,
6
, . . .
As illustrated in
FIG. 14
, in conventional slitting apparatuses for forming magnetic tapes, ordinarily, each of a cutting edge
3
a
′ of an upper slitting blade
3
′ and a cutting edge
4
a
′ of a lower slitting blade
4
′ is formed in an approximately right-angled, sharp angular shape. With the conventional slitting apparatuses, conventional magnetic tapes having a shape as illustrated in
FIG. 15
are ordinarily obtained from the slitting operation with upper slitting blades
3
′,
3
′, . . . and lower slitting blades
4
′,
4
′, . . . , which are respectively provided with the cutting edges
3
a
′,
3
a
′, . . . and the cutting edges
4
a
′,
4
a
′, . . . having the angular shape. Specifically, as illustrated in
FIG. 15
, each magnetic tape
6
′ has side faces
7
and
8
(cut surfaces having been cut by two adjacent upper slitting blades
3
′,
3
′ and corresponding lower slitting blades
4
′,
4
′), which are formed at opposite ends with respect to the width direction of the magnetic tape
6
′. At the side face
8
on the upper slitting blade side, the side face of a back coating layer
11
is located more inward than the side face of a base layer
10
by a distance of &dgr;u in the width direction of the magnetic tape
6
′. Also, at the side face
7
on the lower slitting blade side, the side face of the back coating layer
11
is located more outward than the side face of the base layer
10
by a distance of &dgr;d in the width direction of the magnetic tape
6
′. In
FIG. 15
, reference numeral
12
represents the magnetic layer.
In
FIG. 1
, a side face
3
b
of the upper slitting blade
3
on the side, which stands facing the cutting edge
4
a
of the lower slitting blade
4
, is referred to as the ventral side, and an opposite side face
3
c
of the upper slitting blade
3
is referred to as the back. Also, the side face of each magnetic tape
6
, which side face stands facing the ventral side
3
b
of the upper slitting blade
3
, is referred to as the side face on the lower slitting blade side, and the side face of each magnetic tape
6
, which side face stands facing the back
3
c
of the upper slitting blade
3
, is referred to as the side face on the upper slitting blade side. In
FIG. 1
, the left side face of each magnetic tape
6
is the side face on the lower slitting blade side, and the right side face of the magnetic tape
6
is the side face on the upper slitting blade side.
Nowadays, as in the cases of other kinds of recording media, there is a strong demand for magnetic tapes on which information can be recorded at high densities and which have a high capacity. The inventors conducted extensive research for satisfying the demand and found that, in cases where the side face of the back coating layer
11
is projected to a position more outward than the side face of the base layer
10
in the width direction of the magnetic tape
6
′, the problems described below occur.
Specifically, as the capability of the recording at high densities is required of the magnetic tapes, recording tracks are formed at high densities on the magnetic tapes. In order for the recording tracks to be traced accurately, it is necessary that regulation of the position of the magnetic tape with respect to the width direction of the magnetic tape be tightened during the running operation of the magnetic tape in the recording and read-out apparatus. In cases where regulation of the position of the magnetic tape with respect to the width direction of the magnetic tape is tightened, a contact pressure between the side face of the magnetic tape and a guide for regulating the position of the side face of the magnetic tape becomes high. As a result, the problems occur in that the side face of the back coating layer
11
, which side face is projected outwardly in the width direction of the magnetic tape, is scraped off due to the contact with the guide at the high contact pressure, and the resulting scrapings cause drop-outs, and the like, to occur.
Also, in cases where the side face of the magnetic layer
12
is projected more outward than the side face of the base layer
10
in the width direction of the magnetic tape
6
′, scrapings of the magnetic layer
12
will occur. However, the regulation of the position of the magnetic tape
6
′ with respect to the width direction of the magnetic tape
6
′ is performed particularly on the side of the back coating layer
11
of the magnetic tape
6
′. Therefore, the guide described above primarily comes into contact with the side faces of the base layer
10
and the back coating layer
11
. Accordingly, particularly, the side face of the back coating layer
11
, which side face projects outwardly in the width direction of the magnetic tape
6
′, markedly causes the problems, such as the occurrence of the scrapings and the drop-outs due to the scrapings, to occur.
Also, recently, as a high capacity is required of the magnetic tapes, there is a strong demand for magnetic tapes having a small t
Fujikata Shingo
Iida Sampei
Fuji Photo Film Co. , Ltd.
Kiliman Leszek
Sughrue & Mion, PLLC
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