Advancing material of indeterminate length – By orbitally traveling material-engaging surface – With drive means
Reexamination Certificate
2002-10-17
2004-11-16
Matecki, Kathy (Department: 3654)
Advancing material of indeterminate length
By orbitally traveling material-engaging surface
With drive means
C310S156040, C310S156380, C310S156450, C310S156460, C310S156470, C310S090500
Reexamination Certificate
active
06817507
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a capstan motor for a magnetic recording and reproducing apparatus, and particularly, to a capstan motor which is able to maintain driving height of a tape by preventing a capstan shaft from being vibrated in length direction.
2. Description of the Background Art
Generally, in a magnetic recording and reproducing apparatus, a magnetic tape drives at a constant speed by being inserted between a capstan shaft and a pinch roller which is cohered with the capstan shaft in recording mode and reproducing mode. The capstan shaft is driven by a capstan motor having it as a rotating shaft. The capstan motor is a motor which can be rotated forward and backward, and it can change it's speed from a normal speed for recording and reproducing modes, that is, general function, to a low speed for a long time recording and reproducing or for a slow mode for reproducing slow motion, that is, for special functions.
Principal parts of the magnetic recording and reproducing apparatus will be described with reference to
FIG. 1
as follows.
FIG. 1
is a block diagram showing a tape drive of a general magnetic recording and reproducing apparatus.
In the tape drive of the magnetic recording and reproducing apparatus, a tape
1
which is wound off from a feed reel (not shown) of a tape cassette contacts to a full width erase head
5
for erasing all video and voice control signals recorded on the tape
1
when the tape
1
is in the recording mode, to a video head drum
6
for recording/reproducing video signals, to an audio head
7
for recording/reproducing voice signals, to a control head
8
for recording/reproducing control signal on the tape so that the tape
1
can be driven in a constant speed, and then, wound on a take-up reel (not shown) of the tape cassette.
Herein, a feed reel driving unit
3
and a take-up reel driving unit
4
are installed on one side of a main chassis
2
so as to drive the feed reel and the take-up reel.
Also, a plurality of guide posts
12
,
14
,
16
and
18
for guiding the driving of the tape
1
, and guide rollers of feed side and of take-up side
20
and
22
for supporting the tape
1
and for making the tape draw a natural trajectory are installed on the main chassis
2
.
In addition, a tension post
26
for controlling tensile force in driving the tape
1
is installed on a tension arm
24
. The tension arm
24
is elastically supported by a spring
29
so as to be rotated as a predetermined angle centering around a shaft pin
28
according to the tensile force of the tape
1
.
In addition, a tension brake
27
having both ends fixed on the tension arm
24
respectively is wound on the feed reel driving unit
3
, and the tension brake
27
controls the tension of the tape
1
by controlling the rotating speed of the feed reel driving unit
3
according to operations of the tension arm
24
.
On the other hand, slant bases for feed side and for take-up side
36
and
38
are installed on both sides of the video head
6
so as to wind the tape
1
on the video head
6
, and slant posts for feed side and for take-up side
42
and
44
for guiding the tape
1
toward the video head surface are installed on the slant bases for feed side and for take-up side
36
and
38
.
Also, loading paths
32
and
34
for guiding the slant bases for feed side and for take-up side
36
and
38
when the slant bases are moved are formed on both sides of the video head
6
.
That is, the tape
1
is guided by the slant posts
42
and
44
, then pulled toward the video head
6
when the slant bases
36
and
38
are moved along with the loading paths
32
and
34
, and wound on the video head
6
.
In the magnetic recording and reproducing apparatus constructed as above, the capstan motor
50
and the pinch roller
54
for making the tape
1
drive are disposed, and the capstan motor
50
will be described with reference to
FIGS. 2A and 2B
as follows.
The capstan motor
50
comprises a rotor
47
and a stator
48
, and the rotor
47
comprises a rotor case
58
, a magnet
60
fixedly attached on a periphery of the rotor case
58
for forming a magnetic field required to rotate the capstan motor
50
, a pulley
72
fixed on lower center of the rotor case
58
and rotated integrally with the rotor case
58
for driving reel rotation of the magnetic tape, and a capstan shaft
52
fixedly press-fitted on a center of the pulley
72
and cohered with the pinch roller
54
taking the tape
1
therebetween.
Herein, the capstan shaft
52
is an output shaft of the capstan motor
50
, and the proceeding direction of the tape
1
is decided by the rotating direction of the capstan shaft
52
.
The stator
48
comprises a frame
66
having bearings
64
installed respectively on inner upper and inner lower sides thereof for supporting the rotation of the capstan shaft
52
and a substrate
70
fixed thereon with a coupling bolt
68
, and an armature coil
62
fixed to face the magnet
60
of the rotor
47
on the periphery of the frame
66
for rotating the rotor
47
by electromagnetic interaction with the magnet
60
.
Operation of the capstan motor
50
of the conventional magnet recording and reproducing apparatus constructed as above will be described as follows.
When electric power is applied to the coil
62
, electric force is generated on the coil
62
, and the rotor
47
is rotated by the electromagnetic interaction between the electric force and the magnet
60
.
That is, the rotor
58
is rotated according to that the direction of the magnetic force (fm) of the magnet
60
and the direction of the electromagnetic force (fc) of the coil
62
function vertically to the shaft direction of the capstan shaft
52
.
At that time, the magnetic force (fm) of the magnet
60
and the electromagnetic force (fc) of the coil
62
are not functioned toward the shaft direction of the capstan shaft
52
, and therefore, there is no component of the capstan shaft direction in a resultant force of the magnetic force (fm) and of the electromagnetic force (fc).
In addition, the capstan shaft
52
and the pinch roller
54
are cohered with each other taking the tape
1
therebetween to compress the tape
1
, and these are rotated by the rotating force of the capstan motor
52
to make the tape
1
drive at a constant speed with a constant tensile force.
The capstan motor
50
constructed and operated as above is vibrated in up-and-down direction by outer elements such as mechanical vibration due to the rotation of the rotor
58
and run-out of the pinch roller generated when the capstan shaft
52
is selectively cohered to the pinch roller
54
.
That is, thrust F
1
, F
2
and F
3
are functioned to the capstan shaft
52
, to the tape
1
, and to the pinch roller
54
respectively in the shaft direction of the capstan shaft
52
, and therefore, the capstan shaft
52
is changed toward the shaft direction due to the thrusts, and accordingly, the tape
1
is vibrated in up-and-down direction and traveling height is changed.
In detail, since a frictional force between the pinch roller
54
and the tape
1
is greater than that between the capstan shaft
52
and the tape
1
, the tape
1
is a lot affected by the thrust F
2
of the pinch roller
54
, and the thrust F
2
of the pinch roller
54
is applied forward an opposite direction of the thrust F
1
of the capstan shaft
52
. Therefore, in case that the capstan shaft
52
vibrates by a mechanical vibration according to rotation of the rotor
58
or the pinch roller
54
vibrates by exterior factors such as the run out of the pinch roller
54
, the tape
1
vibrates in the same direction of the pinch roller
54
, thereby changing the traveling height of the tape
1
.
Therefore, when the tape
1
contacts to the video head
6
, to the audio head
7
, and to the control head
8
, etc., the contacting status becomes bad, and therefore, the signal recording and reproducing on the tape
1
are not made precisely.
SUMMARY OF THE INVENTION
Therefore, an object of the present
Birch & Stewart Kolasch & Birch, LLP
Kim Sang
LG Electronics Inc.
Matecki Kathy
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