Head drum apparatus

Details Head drum apparatus Head drum apparatus

1999-12-08

2002-04-09

Cao, Allen (Department: 2652)

Dynamic magnetic information storage or retrieval

Head mounting

For moving head during transducing

Reexamination Certificate

active

06369991

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of Korean Utility Model Application Not.
98-24474
, filed Dec. 8, 1998, in the Korean Patent Office, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a motor for rotating an upper drum, which is provided on a top surface of the upper drum and a top portion of a stationary shaft, in a head drum apparatus for use in a magnetic tape recording and reproducing apparatus; and, more particularly, to a head drum apparatus capable of reducing the number of components and the manufacturing steps by using a single surface printed circuit board (“PCB”), thereby decreasing the production cost, enhancing the manufacturing efficiency, and increasing the productivity thereof.
2. Description of the Related Art
Conventionally, a shaft-rotating type head drum apparatus has been employed in a magnetic tape recording and reproducing apparatus. In the shaft-rotating type head drum apparatus, a rotating shaft is pressed and fitted into an upper drum and a lower drum is rotatably mounted on a lower portion of the rotating shaft. A motor is attached to the bottom surface of the lower drum and activated to rotate the shaft and hence the upper drum. A head provided in the upper drum records or reproduces a signal to or from a magnetic tape.
However, the head drum apparatus of the shaft-rotating type has two freedom degrees and does not fully overcome resonant vibration problems, so that it cannot remove the likelihood of its malfunction due to the resonant vibration upon the rotation of the upper drum.
Recently, in order to solve the above problems, a shaft-fixed type head drum apparatus has been proposed. The typical constitution of the shaft-fixed type head drum assembly will now be described.
As shown in
FIGS. 1 and 2
, a general shaft-fixed type head drum apparatus of a magnetic tape recording and reproducing apparatus comprises: a lower drum
1
having a recessed portion la formed therein, a stationary shaft
2
pressed and fitted into a center hole of the lower drum
1
, a stationary transformer
3
attached to the bottom surface of the lower drum
1
, the stationary transformer
3
having a plurality of concentric channels
3
a
formed on the top surface thereof, a plurality of stator coils
4
wound in the respective channels
3
a
, an upper drum
7
rotatably coupled to the stationary shaft
2
via bearings
5
and
6
fixed on a middle portion and an upper portion of the stationary shaft
2
, respectively, a rotary transformer
8
attached to a bottom surface of the upper drum
7
such that a gap is formed between the rotary and the stationary transformers
8
and
3
, the rotary transformer
8
having a plurality of concentric channels
8
a
on the bottom surface thereof, a plurality of lines of rotor coils
9
wound in the respective channels
8
a
of the rotary transformer
8
, a head assembly
20
and a full-width erasing head assembly
30
fixed to the bottom surface of the upper drum
7
by means of screws
10
, a signal transmitting means for transmitting the signals between the rotor coils
9
of the rotary transformer
8
and the head assembly
20
and the full-width head assembly
30
, and a drum motor provided on the top portion of the stationary shaft
2
and the top surface of the upper drum
7
.
The signal transmitting means uses a flexible printed circuit (“FPC”)
11
. Mounted to a portion of the pattern formed on the FPC is a ceramic condenser (hereinafter referred to as “chip”) which acts as a filter tuning the frequency band within the band of a full-width erasing head
32
.
The head assembly
20
and the full-width erasing head assembly
30
are provided with a video head
22
and the full-width erasing head
32
on the leading ends of head bases
21
and
31
, respectively. The head assembly
20
and the full-width erasing head assembly
30
also have PCBs
23
and
33
with desired patterns on the bottom surfaces thereof, respectively. The video head
22
and the full-width erasing head
32
are electrically connected to the PCBs
23
and
33
, respectively.
On the other hand, the drum motor includes a motor stator
40
fixed to the top portion of the stationary shaft
2
and a motor rotor
50
fixed to the top surface of the upper drum
7
.
Specifically, the motor stator
40
is fitted on the top portion of the stationary shaft
2
and includes a boss
42
into which a set screw
41
is radially screwed, a PCB
43
secured to the bottom surface of the boss
42
, motor stator coils
44
mounted on the top surface of the PCB
43
, and a back yoke
45
mounted on the PCB
43
to cover the motor stator coils
44
. The motor rotor
50
includes a plate
52
fixed to the top surface of the upper drum
7
by means of a plurality of screws
51
and a motor magnet
53
attached to the upper surface of the plate
52
.
Formed on the bottom surface of the PCB
43
are a pulse generator(“PG”) pattern P for controlling the position of the video head
22
mounted to the upper drum
7
and a frequency generator(“FG”) pattern F for performing a regional control as a detail control of the PG pattern P, as shown in
FIGS. 3
to
5
.
The FG pattern F has a wave form which is circumferentially disposed around the center thereof and has two lines, an inner line and an outer line. The PG pattern P is located at a portion on one side of the FG pattern F.
In order to connect a connection pattern C
1
and C
3
formed one surface of the PCB
43
with a connection pattern C
2
and C
4
formed on the other surface, it is necessary to form an another FG pattern F′ and an another PG pattern P′ on the top surface of the PCB
43
, which is opposite to the bottom surface on which the FG pattern F and the PG pattern P are formed. The FG patterns F and F′ are connected to each other through a through hole
43
a
and the PG patterns P and P′ are connected to each other through a through hole
43
b
. The terminals of the FG pattern F′ and the PG pattern P′ are connected to the connection patterns C
2
and C
4
, respectively.
In the above conventional shaft-fixed type head drum apparatus, the upper drum
7
is rotated by an electromagnetic activation of the drum motor provided at the top portion of the stationary shaft
2
and the top portion of the upper drum
7
, the head
22
of the upper drum
7
reproduces or records the signals from or to a tape (not shown) traveling around the outer peripheral surfaces of the upper and the lower drums
7
and
1
, and the full-width erasing head
32
erases the information (signals) recorded on the tape.
On the other hand, the signals from the head
22
and the full-width erasing head
32
are transmitted through in turn the FPC
11
connected to the respective PCBs
23
and
32
, the rotor coils
9
of the rotary transformer
8
and the stator coil
4
of the stationary transformer
3
, to a controller (not shown) or vice versa.
At this time, since the PG patterns P and P′ and the FG patterns F and F′ are formed on the PCB
43
of the motor stator
40
, a motor servo function for controlling the position and section of the upper drum
7
is performed.
However, in the conventional shaft-fixed type head drum apparatus described above, the PCB having both surfaces of which the PG patterns P and P′ and the FG patterns F and F′ are formed is employed, and it is difficult to manufacture the bisurface PCB, thereby resulting in an increased production cost due to the need for the additional back yoke
45
, a decreased operation efficiency and a poor productivity thereof.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a motor of a head drum apparatus capable of reducing a number of components and manufacturing steps by using monosurface printed circuit board (“PCB”) thereby decreasing the production cost, enhancing the manufacturing efficiency and increasing the productivity thereof.
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