Pinch roller bearing structure for magnetic tape apparatus

Details Pinch roller bearing structure for magnetic tape apparatus Pinch roller bearing structure for magnetic tape apparatus

2000-05-01

2002-07-16

Walsh, Donald P. (Department: 3653)

Advancing material of indeterminate length

By orbitally traveling material-engaging surface

Including details of roll or mount

C226S186000, C242S346200, C384S276000, C384S295000

Reexamination Certificate

active

06419139

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a magnetic tape apparatus in which a bearing interposed between a pinch roller and a roller shaft has been improved.
One example of a related magnetic tape apparatus will be described referring to
FIG. 4. A
feed reel stand
2
is engaged with a feed reel in the tape cassette
1
. A take-up reel stand
3
is engaged with a take-up reel in the tape cassette
1
. A movable tape guide post
4
draws out a magnetic tape t from the tape cassette
1
and winds it around a head cylinder
5
. Reference numerals
6
,
7
and
8
denote an entire erasing head, an audio erasing head and an audio control head, respectively. Reference numerals
9
,
10
and
11
denote a stationary tape guide post, a back tension post and a capstan roller, respectively. A pinch roller
12
is rotatably disposed at one end of a supporting arm
14
which is rotatable around a pivotal shaft
13
. At the other end of the supporting arm
14
is provided a cam pin
15
which is movably engaged in a cam groove
16
a
of a rotary cam
16
.
In the above described structure, in a recording or a reproducing mode, for example, the magnetic tape t is drawn out from the tape cassette
1
by means of the movable tape guide post
4
and wound around the head cylinder
5
as shown in the drawing. Then, by rotating the rotary cam
16
at a determined angle to swing the supporting arm
14
, the pinch roller
12
is pressed against the capstan roller
11
together with the magnetic tape in between to rotatively drive the capstan roller
11
whereby the magnetic tape t is caused to run.
A first related bearing structure for the pinch roller
12
has been disclosed in Japanese Patent Publication No. 10-228692A. In this structure, as shown in
FIG. 5
, the pinch roller
12
is so provided as to enclose an upper small-diameter portion
18
a
of a roller shaft
18
which is projectingly provided at one end of the supporting arm
14
by way of a bearing
19
. The bearing
19
is formed of a synthetic resin and consists of an inner cylindrical portion
19
a,
an outer cylindrical portion
19
b
which are concentrically overlaid leaving a determined space therebetween, and a thin walled connecting portion
19
c
which interconnects the cylindrical portions
19
a
and
19
b
integrally at their middle portions. The pinch roller
12
consists of a cylindrical sleeve
12
a
formed of metal, and an elastically deformable roller body
12
b
formed of rubber or the like and attached to an outer peripheral face of the sleeve
12
a.
In
FIG. 5
,
21
denotes a washer, and
22
and
23
denote retaining members.
In the above described structure, when the pinch roller
12
is pressed against the capstan roller
11
together with the magnetic tape t in between, an inclination from a paralleled state of an axis O
2
of the pinch roller
12
with respect to an axis O
1
of the capstan roller
11
is so adapted to be absorbed by a clearance C between the bearing
19
and the roller shaft
18
and also by a so-called automatic centering function through elastic deformation of the bearing
19
.
In the above described structure, because the outer peripheral face of the outer cylindrical portion
19
b
composing the bearing
19
is tightly fitted to an inner face of the sleeve
12
a
over the entire face, it has been difficult and annoying to insert the bearing
19
into the sleeve
12
a.
Moreover, the thin walled connecting portion
19
c
is pressed inwardly by inserting the bearing
19
into the sleeve
12
a,
and a bearing bore
20
formed through the inner cylindrical portion
19
a
is shrunk in diameter at a middle portion of its inner peripheral face, which will change an inner diameter of the bearing bore
20
. Therefore, when the pinch roller
12
is engaged with the small-diameter portion
18
a
of the roller shaft
18
by way of the bearing
19
which has thus changed in the inner diameter, there has been a fear that a large difference may be created in alignment between the axis O
2
of the pinch roller
12
and the axis O
1
of the capstan roller, and a reliable function of the automatic centering mechanism may not be attained.
A second related art is disclosed in Japanese Patent Publication No. 10-172202A. In this structure, as shown in
FIG. 6
, the connecting portion
19
c
is positioned between the lower ends of the inner and the outer cylindrical portions
19
a,
19
b,
and a large-diameter portion
20
a
is formed at a lower end of the bearing bore
20
so as to face with the connecting portion
19
c.
The above described structure has had such an advantage that even though the thin walled connecting portion
19
c
is pressed inwardly by inserting the bearing
19
into the sleeve
12
a
and the bearing bore
20
is partially shrunk in diameter at the inner peripheral face thereof, the shrinkage will be absorbed by the large-diameter portion
20
a.
However, there has been a fear that the connecting portion
19
c
may be worn out in a relatively short period since a pressing force of the pinch roller
12
is concentrically applied to the connecting portion
19
c.
SUMMARY OF THE INVENTION
In view of the above described problems, it is an object of the present invention to provide a magnetic tape apparatus in which a bearing can be easily inserted into a pinch roller, an automatic centering function can be fully exerted, and a life of the bearing can be maintained for a long period.
In order to achieve the above objects, according to the present invention, there is provided a magnetic tape apparatus comprising:
a capstan roller; and
a pinch roller for driving a magnetic tape loaded in the magnetic tape apparatus together with the capstan roller, including:
a tubular roller member, an outer periphery of which is to be abutted against the capstan roller by way of the magnetic tape;
a tubular bearing member provided inside of the roller shaft, the bearing member made of a resin material, and having a groove portion formed on a longitudinal center portion of an outer periphery thereof so as to form flange portions abutting against an inner periphery of the roller member in both longitudinal sides of the groove portion; and
a roller shaft provided inside of the bearing member.
According to the above described structure, the outer peripheral face of the bearing member is only partially fitted to the inner face of the roller member. Accordingly, the bearing member can be easily inserted into the roller member with a smaller force. Further, since the pressing force from the roller member is dispersively exerted on a pair of the flange portions, the pressing force will not damage the flange portions, and the life of the bearing can be maintained for a long period.
Preferably, the diameter of portions of the inner periphery of the bearing member where oppose to the flange portions are enlarged than the diameter of a portion where opposes to the groove portion.
According to the above described structure, since only the middle portion of the inner periphery of the bearing member is brought into contact with the roller shaft, and thereby a width of the portion in contact is small, the so-called automatic centering function can be fully exerted.
Preferably, the enlarged portions of the inner periphery of the bearing member are tapered faces formed so as to gradually enlarged outward.
According to the above described structure, the opposite ends of the inner periphery of the bearing member will not interfere with the roller shaft and will not do harm to the automatic centering function, even in case where the pinch roller is inclined to a relatively large extent.
Preferably, a width of each enlarged portion of the inner periphery of the bearing member in the longitudinal direction thereof is wider than a width of each flange portion in the longitudinal direction of the bearing member.
According to the above described structure, when the bearing member is inserted into the roller member, inward pressing forces are exerted on the flange portions and the opposite ends of the inner peripher

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