Dynamic magnetic information storage or retrieval – Head mounting – For moving head during transducing
Reexamination Certificate
2002-01-25
2004-08-03
Klimowicz, William (Department: 2652)
Dynamic magnetic information storage or retrieval
Head mounting
For moving head during transducing
Reexamination Certificate
active
06771471
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a rotary head drum apparatus and a magnetic recording and playback apparatus, and more particularly to a rotary head drum apparatus and a magnetic recording and playback apparatus wherein a head provided on a rotary head is used to write and/or play back a signal onto and/or from a tape-type recording medium.
In a magnetic recording and playback apparatus of the helical scan type such as a video tape recorder (VTR) wherein a magnetic head contacts with a magnetic tape to effect magnetic recording of the helical scan type onto the magnetic tape, transfer of a signal must be performed between the rotating magnetic head and a circuit on the stationary side. Therefore, as disclosed, for example, in Japanese Patent Laid-Open No. Hei 5-274603, a cylindrical rotary transformer is used, and a stator of the rotary transformer is mounted on an outer circumferential face of a center boss of a stationary drum while a rotor of the rotary transformer is mounted on an inner circumference side of the rotary drum and besides the rotor and the magnetic head are connected to each other by a lead.
However, if it is tried to perform transfer of both of a recording signal and a playback signal at the same time using such a single rotary transformer as disclosed in Japanese Patent Laid-Open No. Hei 5-274603 mentioned above, the recording signal and the playback signal become likely to suffer from deterioration in characteristic by interference, crosstalk or the like on the rotary transformer. This problem is serious particularly where the drum is small in size and besides the video tape recorder is of the multi-channel type wherein many channels are involved. Therefore, a writing rotary transformer and a playback rotary transformer are provided separately from each other so that a writing signal and a playback signal may be transferred separately from each other.
FIG. 3
shows an example of a conventional head drum apparatus which includes a playback rotary transformer and a write rotary transformer provided separately from each other. Referring to
FIG. 3
, the head drum apparatus shown includes an upper side rotary drum
1
, a lower side stationary drum
2
, and a motor
3
provided below the stationary drum
2
. A magnetic head
4
is mounted on the rotary drum
1
such that it is exposed to the outer circumference of the rotary drum
1
.
A playback rotary transformer
6
is disposed above the rotary drum
1
. The playback rotary transformer
6
includes a rotor
7
and a stator
8
. The rotor
7
is mounted at an upper portion of the rotary drum
1
through a mounting plate
9
. Meanwhile, the stator
8
is secured to and supported on a mounting bracket
12
through a mounting plate
10
and an arm
11
.
A writing rotary transformer
14
is provided on the inner side of the stationary drum
2
. The writing rotary transformer
14
includes a rotor
15
and a stator
16
. The rotor
15
is supported on a flange
18
fitted on a rotary shaft
17
. Meanwhile, the stator
16
is secured directly to an upper face of a bottom portion of the stationary drum
2
.
The rotary shaft
17
is supported for rotation on the stationary drum
2
by a pair of upper and lower bearings
21
and
22
. The rotary shaft
17
serves also as a rotary shaft of the motor
3
, and a rotor boss
23
of the motor
3
is secured to an end portion of the rotary shaft
17
. A rotor yoke
24
is securely mounted on the rotor boss
23
, and a ring-shaped magnet
25
is securely mounted on an upper face of the rotor yoke
24
.
The magnet
25
of the motor
3
is opposed to a coil
26
with an air gap left therebetween. The coil
26
is mounted on a printed circuit board
27
. A shield plate
28
is disposed above the printed circuit board
27
, and an outer peripheral wall of the motor
3
is formed from a casing
29
secured to a lower face of the stationary drum
2
.
In the head drum apparatus having such a configuration as described above, when the coil
26
on the printed circuit board
27
of the motor
3
is energized, then the magnet
25
mounted on the rotor yoke
24
is acted upon by a force in its rotational direction thereby to rotate the motor
3
. The rotation of the motor
3
is transmitted to the rotary drum
1
securely mounted on the rotary shaft
17
so that the rotary drum
1
is rotated. Consequently, the magnetic head
4
mounted on the rotary drum
1
is rotated. A magnetic tape wrapped around and extending between outer circumferential portions of the rotary drum
1
and the stationary drum
2
is opposed to and contacts with the magnetic head
4
.
In writing operation, a signal is transmitted from the circuit on the stationary side to the magnetic head
4
on the rotary drum
1
through the stator
16
and the rotor
15
of the writing rotary transformer
14
. The signal is written on the magnetic tape. In contrast, in playback operation, a signal of the magnetic tape is read out by the magnetic head
4
and transmitted to the circuit of the stationary side through the rotor
7
and the stator
8
of the playback rotary transformer
6
.
In the rotary head apparatus, a favorable characteristic is obtained by providing the playback rotary transformer
6
and the writing rotary transformer
14
in such a manner as shown in FIG.
3
and disposing them in a spaced relationship from each other by a distance as great as possible. Therefore, the rotary transformer
14
is accommodated in the inside of the stationary drum
2
, and the playback rotary transformer
6
is disposed above the rotary drum
1
.
With the arrangement just described, however, the stator
8
of the playback rotary transformer
6
disposed above the upper side rotary drum
1
must be secured to the rotary drum
1
using such separate structural parts as the mounting plate
10
, arm
11
, mounting bracket
12
. Such a complicated structure as described above is unfavorable in terms of the facility in assembly and the accuracy in assembly and in terms of the cost. Further, the structure makes rework such as exchange of the magnetic head
4
or the like difficult. Particularly where the rotary head drum apparatus is designed for multi-channels and includes many heads, the possibility that a trouble may occur is high. Further, since the playback rotary transformer
6
which has a considerable weight is provided above the rotary drum
1
, the rotary head drum apparatus is disadvantageous in dynamic balance and is not suitable for high speed rotation.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a rotary head drum apparatus and a magnetic recording and playback apparatus which are improved in facility in assembly and accuracy in assembly, facilitate rework of a head and the like and assure improved dynamic stability while eliminating the structure wherein one of a writing rotary transformer and a playback rotary transformer is mounted on the upper portion of the rotary drum with a mounting plate, an arm, a mounting bracket and the like.
In order to attain the object described above, according to an aspect of the present invention, there is provided a magnetic recording and playback apparatus and a rotary head drum apparatus, comprising a rotary drum having a head thereon, a stationary drum disposed coaxially with the rotary drum and having, on an outer circumferential face thereof, a guide face for a tape-type recording medium which is opposed to and contacts with the head, and a writing rotary transformer and a playback rotary transformer disposed in a neighboring relationship with each other in an axial direction with a shield plate interposed therebetween and accommodated in the stationary drum.
With the rotary head drum apparatus, upon replacement of the head, the writing rotary transformer and the playback rotary transformer need not be disassembled. Consequently, the rework facility upon replacement of the head is improved. Besides, otherwise possible crosstalk of a writing signal and a playback signal between the two rotary transformers is prevented by the sh
Fujimori Motoyoshi
Hashimoto Ichiro
Itou Akira
Kaneko Hiroyuki
Cooper & Dunham LLP
Klimowicz William
Sony Corporation
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