Winding – tensioning – or guiding – Unwinding and rewinding a machine convertible information... – With particular drive
Reexamination Certificate
2002-05-20
2003-11-04
Nguyen, John Q. (Department: 3654)
Winding, tensioning, or guiding
Unwinding and rewinding a machine convertible information...
With particular drive
C360S096300
Reexamination Certificate
active
06641073
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a reel mount of a magnetic recording/reproducing apparatus which stably maintains tension on a magnetic tape wound around a reel which is placed on the reel mount when taking up/feeding the magnetic tape in/from a cassette.
2. Description of the Related Art
Recently, among magnetic recording/reproducing apparatuses, videotape camera-recorders are becoming more compact and less expensive.
Referring to
FIGS. 3 and 4
, a structure of a conventional reel mount of a conventional magnetic recording/reproducing apparatus will be described below.
FIG. 3
is a top view of a conventional reel mount.
FIG. 4
is a cross-sectional view of the conventional reel mount taken along line B—B shown in FIG.
3
.
In
FIG. 4
, reference numeral
1
a
denotes a reel in a cassette. A (magnetic) tape (not shown) is wound around the reel
1
a
. Reference numeral
1
b
denotes a body of the cassette, reference numeral
2
denotes a chassis of a conventional magnetic recording/reproducing apparatus, and reference numeral
3
denotes a rotation shaft provided in the chassis
2
. The conventional reel mount is placed on the rotation shaft
3
so as to be rotatable with respect to an axis of the rotation shaft
3
(shown as a broken line in FIG.
4
). Reference numeral
303
denotes an upper reel mount member on which the reel
1
a
is mounted, reference numeral
305
denotes a rotation engagement member which is movable up and down (i.e., in a direction parallel to the axis of the rotation shaft
3
) and is engaged with the upper reel mount member
303
and the reel
1
a
along a rotation direction of the reel mount, reference numeral
304
denotes a spring which applies upward force to the rotation engagement member
305
with respect to the movement thereof such that the rotation engagement member
305
is engaged with a protruded portion of the upper reel mount member
303
and is supported by the upper reel mount member
303
and the spring
304
, and reference numeral
307
denotes a yoke board provided in the form of a disk and made of a ferromagnet, such as a rolled steel board.
The yoke board
307
is integrally formed with the upper reel mount member
303
. It is common practice in the field of magnetic recording/reproducing apparatuses to integrally form a yoke board member, such as the yoke board
307
, with an upper reel mount member, such as the upper reel mount member
303
, by outsert molding. The upper reel mount member
303
integrally formed with the yoke board
307
is rotatable with respect to the rotation shaft
3
. Reference numeral
308
denotes a magnet which applies magnetic force so that the magnet
308
is attached to and rotated with the yoke board
307
due to rotation of the upper reel mount member
303
. Lines of magnetic force (not shown) generated by the magnet
308
form a magnetic loop passing through the yoke board
307
.
Reference numeral
310
denotes a lower reel mount member integrally formed with a hysteresis board
311
having a disk-like shape. The hysteresis board
311
is made of a material having large magnetic hysteresis loss. It is common practice in the field of magnetic recording/reproducing apparatuses to integrally form a hysteresis board member, such as the hysteresis board
311
, with a lower reel mount member, such as the lower reel mount member
310
, by outsert molding. Similar to the upper reel mount member
303
, the lower reel mount member
310
integrally formed with the hysteresis board
311
is placed on the rotation shaft
3
so as to be rotatable with respect to the rotation shaft
3
. The lower reel mount member
310
is attracted by the magnetic force of the magnet
308
so as to be in contact with the upper reel mount member
303
.
Reference numeral
309
denotes a washer sandwiched between the lower real mount member
310
integrally formed with the hysteresis board
311
and the upper reel mount member
303
. The washer
309
is engaged with the lower reel mount member
310
so as to be rotated therewith. Reference numeral
302
denotes a gear member provided to the outer circumference of the lower reel mount member
310
, which is engaged with an external gear (not shown). Reference numeral
306
denotes a reel bearing member provided on the upper reel mount member
303
and integrally formed with the yoke board
307
so as to come into contact with the reel
1
a
when the reel
1
a
is mounted on the conventional reel mount. Similar to other reel mount members, it is common practice in the field of magnetic recording/reproducing apparatuses to integrally form a reel bearing member, such as the reel bearing member
306
, with a yoke board member, such as the yoke board
307
. by outsert molding.
When the reel
1
a
is mounted on the conventional reel mount, a position in a vertical direction of the reel
1
a
with respect to the chassis
2
is defined by the reel bearing member
306
. Reference numeral
4
denotes a washer placed between the reel mount and the base of the rotation shaft
3
and reference numeral
5
denotes a washer placed on the rotation shaft
3
so as to define movement of the reel mount along a thrust (vertical) direction of the reel mount and to provide a space between the rotation shaft
3
and the upper reel mount member
303
.
Operation of the conventional reel mount is described below.
When the lower reel mount member
310
is rotated by the external gear (not shown) through engagement with the gear member
302
, friction torque is generated between the upper and lower reel mount members
303
and
310
via the washer
309
due to the magnetic attraction generated by the magnet
308
on the lower and upper parts of the reel mount. Simultaneously, the hysteresis board
311
is rotated through the magnetic loop generated by the magnet
308
, so that magnetic hysteresis torque is generated. The friction torque and magnetic hysteresis torque result in clutch torque between the upper reel mount member
303
and the lower reel mount member
310
so that the reel
1
a
mounted on the upper reel mount member
303
is rotated by the rotation engagement member
305
while sufficient tension is applied to the magnetic tape wound around the reel
1
a
. The amount of clutch torque generated by the conventional reel mount is determined by the magnetic attraction and force generated by the magnet
308
and the position in the vertical direction of the reel
1
a
with respect to the chassis
2
is determined by the reel bearing member
306
.
However, in the conventional reel mount, space K shown in
FIG. 4
is provided between the reel
1
a
and the yoke board
307
due to the presence of the reel bearing member
306
, thereby limiting a size of the magnet
308
. When the size of the magnet
308
is reduced, it is not possible to realize a reel mount which provides sufficient clutch torque, since a smaller magnet generates smaller magnetic attraction and force. Thus, the space K (i.e., the presence of the reel bearing member
306
) prevents a compact reel mount which provides sufficient clutch torque from being realized. Furthermore, when using an inexpensive magnetic material, such as ferrite, for the magnet
308
, such a magnetic material provides lower magnetic force as compared to an expensive magnetic material having high magnetic force, such as samarium cobalt. Thus, compared to a magnet of samarium cobalt, the volume of the magnet having a lower magnetic force is required to be greater so as to provide sufficient magnetic force such that the reel mount can have sufficient clutch torque. Therefore, the space K (i.e., the presence of the reel bearing member
306
) also prevents a reduction in production cost of the conventional reel mount.
Further still, in the conventional reel mount, the position in the vertical direction of the conventional reel mount with respect to the chassis
2
is important for enabling a tape wound around the reel
1
a
to stably traverse the reel in a cassette, and this position is accurately defined by a h
Hirabayashi Koichiro
Shibukawa Kazuo
LandOfFree
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