Pinch roller device

Details Pinch roller device Pinch roller device

2002-05-09

2004-07-06

Matecki, Kathy (Department: 3654)

Advancing material of indeterminate length

By orbitally traveling material-engaging surface

Including details of roll or mount

C226S180000, C384S192000, C384S297000, C384S909000

Reexamination Certificate

active

06758381

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pinch roller device used in a magnetic recording and reproduction apparatus such as a video tape recorder.
2. Description of the Related Art
Recently, there has been a strong demand for more compact, lightweight and lower-cost video tape recorders integrated with cameras. In order to fulfill such demand, it is important to improve the structure of a tape driving device which is included in such recorders and that includes a pinch roller device.
FIG. 15
is a cross-sectional view of a conventional pinch roller device
150
. The pinch roller device
150
includes a rotatable capstan shaft
1
, a metal sleeve
22
, an elastic member
3
formed of rubber, for example, and fixed on an outer circumferential surface of the metal sleeve
22
, and a bearing
11
having collars
13
. The bearing
11
and the sleeve
22
are integrated together by the collars
13
being pressure-inserted into an inner circumferential surface of the sleeve
22
. The pinch roller device
150
further includes a pinch roller shaft
5
for rotatable supporting the bearing
11
, and a pinch arm
9
for carrying the pinch roller shaft
5
projecting therefrom. The bearing
11
has an effective bearing face
12
for receiving a force from the pinch roller shaft
5
applied in a radial direction of the pinch roller shaft
5
. The bearing
11
, the metal sleeve
22
, the collars
13
and the elastic member
3
form an assembly
50
. The pinch roller shaft
5
is provided therearound with a first position restriction member
7
having a restriction surface
7
a
for restricting movement of the elastic member
3
in an upward thrust direction (arrow N), and a second position restriction member
8
having a restriction surface
8
a
for restricting movement of the elastic member
3
in a downward thrust direction (arrow N). Reference numeral
10
represents a tape used for data recording and reproduction.
In the pinch roller device
150
having the above-described structure, the tape
10
runs at a prescribed speed by putting the tape
10
into pressure-contact with the capstan shaft
1
by the elastic member
3
while rotating the capstan shaft
1
.
In order to stably run the tape
10
, the elastic member
3
needs to press the tape
10
uniformly toward the capstan shaft
1
, preferably in the state where the capstan shaft
1
and the pinch roller shaft
5
are parallel to each other. However, for reasons related to the production process, it is inevitable that the pinch roller shaft
5
slightly inclines with respect to the capstan shaft
1
. Therefore, it is difficult to dispose the pinch roller shaft
5
and the capstan shaft
1
completely parallel to each other.
FIG. 16
is an enlarged partial view of the pinch roller device
150
, illustrating the pinch roller shaft
5
and the vicinity thereof. As shown in
FIG. 16
, the pinch roller shaft
5
and the effective bearing face
12
of the bearing
11
have a gap therebetween having a size LD in a radial direction of the bearing
11
. Using this gap, the elastic member
3
is inclined with respect to the assembly
50
(FIG.
15
), so that the pinch roller shaft
5
is parallel to the capstan shaft
1
. More specifically, a rotation center line
11
a
of the bearing
11
is inclined with respect to a rotation center line
5
a
of the pinch roller shaft
5
at angle &thgr; in a direction in which the elastic member
3
presses the tape
10
toward the capstan shaft
1
(represented by arrow M). In this manner, the elastic member
3
can uniformly pressure the tape
10
toward the capstan shaft
1
. Herein, the direction of arrow M is also referred to as a “tape thickness direction”.
The conventional pinch roller device
150
has the following problems.
(1) When the size LD of the gap between the effective bearing face
12
and the pinch roller shaft
5
is larger, the freedom in angle &thgr; is also larger. This is preferable in order to accommodate an error in the angle of inclination of the pinch roller shaft
5
with respect to the capstan shaft
1
caused in the production process and thus guarantee stable running of the tape
10
.
However, when the size LD is too large, the angle of inclination of the rotation center line
11
a
with respect to the rotation center line
5
a
in a tape running direction (perpendicular to the sheet of
FIG. 16
) is also increased. This is undesirable for the following reason. In general, when the running direction of the tape
10
is changed from forward to reverse or from reverse to forward, the direction of inclination of the elastic member
3
with respect to the capstan shaft
1
is reversed. Where the angle of inclination of the rotation center line
11
a
(i.e., the angle of inclination of the elastic member
3
) with respect to the rotation center line
5
a
in the tape running direction is too large, the height of the tape
10
with respect to the surface of the capstan shaft
1
rapidly changes when the running direction of the tape
10
is changed. This can damage the tape
10
or cause unstable running of the tape
10
. Therefore, in the running direction of the tape
10
, the size LD of the gap preferably has a minimum possible size.
Accordingly, the size LD of the gap needs to be appropriately set so that the angle of inclination of the rotation center line
11
a
with respect to the rotation center line
5
a
in both of the above-mentioned two directions, is in a range which guarantees stable running of the tape
10
. In order to satisfy such contradicting requirements, the variation in the size LD needs to be reduced and an effective length LB of the effective bearing face
12
in the thrust direction needs to be sufficiently large.
In order to reduce the variation in the size LD, the size precision of the components of the pinch roller device
150
needs to be strictly controlled. In addition, when the effective length LB is larger, the distance from the center of the effective bearing surface
12
in the thrust direction to the contact point between the pinch roller shaft
5
and the effective bearing face
12
is longer. This makes it difficult to put the elastic member
3
into uniform pressure-contact with the capstan shaft
1
. This is also undesirable to guarantee stable running of the tape
10
.
(2) The collars
13
are required in order to secure the bearing
11
inside the sleeve
22
. Since the collars
13
need to be reduced in thickness in order to reduce the size of the pinch roller device
150
, the collars
13
are usually formed of metal. When the metal collars
13
are pressure-inserted into an inner circumference of the sleeve
22
, the collars
13
may undesirably become fixed in the thrust direction while being in contact with the bearing
11
. In this state, the collars
13
may deform the bearing
11
.
(3) As shown in
FIG. 15
, the assembly of the pinch roller shaft
5
, the first position restriction member
7
and the second position restriction member
8
has a stepped structure. The restriction surface
8
a
, which is slidably engaged with the bearing
11
, needs to be highly smooth in order to reduce friction resistance upon the bearing
11
. However, due to the stepped shape of the assembly, the restriction surface
8
a
cannot be smoothed by a low-cost smoothing technique, such as, for example, centerless polishing. This increases the production cost of the pinch roller shaft
5
.
SUMMARY OF THE INVENTION
A pinch roller device for putting a tape into pressure-contact with a capstan shaft for running the tape includes a hollow cylindrical elastic member rotating while the tape is running; a sleeve provided on an inner surface of the elastic member for holding the elastic member; a bearing integrated with the sleeve; a pinch roller shaft inserted through the bearing for rotatably supporting the bearing: an inclination restriction member integrated with the pinch roller shaft for restricting an angle of inclination of the pinch roller shaft with respect to the elastic member; a first position res

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