Magnetic tape recording and reproducing apparatus preventing axial vibration of rotary head cylinder

A magnetic tape recording and reproducing apparatus prevents vibration caused by rotation of a rotary drum constituting a rotary head cylinder. The magnetic tape recording and reproducing apparatus includes a drum base having a through-hole, a static drum fixed on the drum base, a rotary drum having at least one head for recording and reproducing a signal on and from a magnetic tape, and a shaft which penetrates the central axis of the rotary drum and the static drum and is bearing-coupled with the rotary drum. An axial support portion which is engaged with the shaft, and inserted into the through-hole of the drum base, elastically supports the shaft so that the shaft maintains the central axial direction during rotation of the rotary drum, with a result that an axial vibration caused by the rotation of the rotary drum can be prevented.

BACKGROUND OF THE INVENTION 
The present invention relates to a magnetic tape recording and reproducing 
apparatus having a rotary head cylinder, and more particularly, to a 
magnetic tape recording and reproducing apparatus which can prevent 
vibration caused by rotation of a rotary drum constituting a rotary head 
cylinder. 
A general magnetic tape recording and reproducing apparatus having a rotary 
head cylinder records a signal on a magnetic tape or reproduces the signal 
therefrom. Such a magnetic tape recording and reproducing apparatus uses a 
rotary head cylinder on which at least one head is installed in order to 
read recorded data from a magnetic tape or records data thereon. A case 
where such a rotary head cylinder is used in an apparatus requiring a high 
speed rotation and a high density recording such as a digital video 
cassette recorder (VCR) will be described with reference to FIG. 1. 
FIG. 1 is a sectional view showing a rotary head cylinder for use in a 
conventional magnetic tape recording and reproducing apparatus. The rotary 
head cylinder shown in FIG. 1 includes a cylindrical rotary drum 10 which 
rotates at high speed, a cylindrical static drum 20 which is located in 
the lower side of the rotary drum 10, and a shaft 18 which penetrates the 
central axis of the rotary drum 10 and the static drum 20 and is inserted 
into a through-hole 32 provided in the static drum 20. 
The rotary drum 10 is connected with the shaft 18 via a bearing 16, and 
includes a motor unit 12 for rotation of the rotary drum 10 therein. The 
rotary drum 10 has the same diameter as the upper portion of the static 
drum 20. A head 14 for recording data on a magnetic tape or reproducing 
data therefrom is installed on the edges in the lower surface of the 
rotary drum 10. The head 14 is disposed so that it is embedded by a minute 
distance from the circumferential surface of the rotary drum 10 toward the 
shaft 18. A tape lead 22 for guiding the magnetic tape is formed on the 
outer circumferential surface of the static drum 20. The tape lead 22 
guides the magnetic tape via contact to the magnetic tape so that the head 
14 can facilitate a recording and reproduction operation with respect to 
the magnetic tape. 
Fixed protrusions 26 formed on the upper surface of a drum base 24 are 
inserted into insertion holes 28 formed on the lower edges of the static 
drum 20. Screw grooves 34 for fixing the static drum 20 to the drum base 
24 are formed between the insertion holes 28. A number of the screw 
grooves 34 are installed in the lower surface of the static drum 20 in the 
form of surrounding the shaft 18, and are individually connected with 
fixed screws 30. The static drum 20 is fixed to the drum base 24 by such a 
screw coupling. 
The rotary head cylinder having the above-described structure does not have 
a complete symmetrical structure by weight around a rotational axis. As a 
rotary head cylinder becomes compact, a static drum is fabricated to 
become thinner and thinner as well. Therefore, when such a rotary head 
cylinder rotates at high speed, an axial vibration occurs. The axial 
vibration deforms the thin static drum 20 in thickness even though a small 
amount of load is applied to the rotary head cylinder. That is, the 
vibration shock caused by the rotary drum 10 is transferred to the static 
drum 20 via the shaft 18, to thereby deform the shape of the thin static 
drum 20. Such a deform of the static drum causes the tape lead 22 not to 
guide a magnetic tape well. As a result, the head installed on the rotary 
drum 10 does not trace accurately with respect to the magnetic tape. 
Also, in the case of a camcorder, noise generated by the rotary head 
cylinder may be recorded on a mantic tape together with a recording 
signal. 
SUMMARY OF THE INVENTION 
To solve the above problems, it is an object of the present invention to 
provide a magnetic tape recording and reproducing apparatus having a 
rotary head cylinder for effectively reducing deformation of a static drum 
from an effect of axial vibration caused by rotation of a rotary drum. 
To accomplish the above object of the present invention, there is provided 
a magnetic tape recording and reproducing apparatus comprising: a drum 
base having a through-hole; a static drum fixed on the drum base; a rotary 
drum having at least one head for recording and reproducing a signal on 
and from a magnetic tape; a shaft which penetrates the central axis of the 
rotary drum and the static drum and is bearing-coupled with the rotary 
drum; and axial support means which is engaged with the shaft, inserted 
into the through-hole of the drum base, and elastically supports the shaft 
so that the shaft maintains the central axial direction during rotation of 
the rotary drum. 
In an embodiment of the present invention, the axial support means 
comprises a connection member which is inserted into the through-hole of 
the drum base, and is screw-coupled with a female screw portion of the 
shaft in which a head is formed in the opposite side of the static drum 
around the drum base; and an elastic member which is supported by the head 
of the connection member and the surface of the drum base facing the head, 
to thereby elastically support the shaft. 
In another embodiment of the present invention, the axial support means 
comprises a connection member which is inserted into the through-hole of 
the drum base, and having a first male screw portion which is 
screw-coupled with a female screw portion of the shaft and a second male 
screw portion formed in the opposite side of the first male screw portion 
around the drum base; a nut which is screw-coupled with the second male 
screw portion and an elastic member which is supported by the nut and the 
surface of the drum base facing the nut, to thereby elastically support 
the shaft.

DETAILED DESCRIPTION OF THE INVENTION 
Preferred embodiments of the present invention will be described in detail 
with reference to the accompanying drawings. 
In FIG. 2, a rotary head cylinder for use in a magnetic tape recording and 
reproducing apparatus according to an embodiment of the present invention, 
includes a rotary drum 10, a shaft 40, a drum base 44 and a static drum 
70. The shaft 40 has screw grooves which are coupled with the static drum 
70, differently from the shaft 18 of FIG. 1. The drum base 44 is spaced 
from protrusion 60 which is located in the lower central portion of the 
static drum 70. Fixed protrusions 26 which are formed on the upper surface 
of the drum base 44 are inserted into insertion holes 28 which are formed 
on the edges in the lower surface of the static drum 70. The fixed 
protrusions 26 are arranged on the drum base 44 as shown in FIG. 3 showing 
an exploded perspective view of the FIG. 2 rotary head cylinder. 
The drum base 44 also includes a through-hole 56 which is formed along the 
central axis line of the shaft 40. A fixing screw 48 is inserted into the 
through-hole 56 and is screw-coupled with the screw groove 50 on the shaft 
40. A spring 52 is installed between the head of the fixing screw 48 and 
the drum base 44. The spring 52 is supported by the head of the fixing 
screw 48 and the drum base 44 facing the head, to there by provide an 
elastic force between the shaft 40 and the fixing screw 48. In particular, 
the spring 52 provides a proper elastic force so that an axial vibration 
is not generated by the rotary drum 70 even though the rotary drum 70 
rotates at high speed. In an embodiment of the present invention, the 
spring 52 is a coil spring, however, it may be replaced by a plate spring 
or a rubber spring. 
In the FIG. 2 embodiment, the static drum 70 is fixed to the drum base 44 
via the fixed protrusions 26 and the insertion holes 28, and the axial 
vibration is prevented via the fixing screw 48 and the spring 52. Thus, 
the FIG. 2 rotary head cylinder can be easily fabricated compared with the 
FIG. 1 apparatus using the screw grooves 34 and the fixing screw 30. 
The other components among the FIG. 2 elements are the same as those of 
FIG. 1 and thus a reassigned with the same reference numerals. Also, since 
the structure, layout and function of the FIG. 2 elements corresponding to 
those of FIG. 1 are same as those of FIG. 1, the detailed description 
thereof will be omitted. 
FIG. 4 is a sectional view showing a rotary head cylinder for use in a 
magnetic tape recording and reproducing apparatus according to another 
embodiment of the present invention. The rotary head cylinder of FIG. 4 
uses a screw member 58 on both ends of which male screw threads are formed 
instead of the fixing screw 48 of FIG. 2. The screw member 58 is 
screw-coupled with screw grooves 50 on which female threads are formed in 
the lower side of the shaft 40. Also, the screw member 58 is screw-coupled 
with a nut 54 in the lower side of the drum base 44. The spring 52 is 
interposed between the drum base 44 and the nut 54, and provides a proper 
elastic force so that an axial vibration is not generated by the rotary 
drum 70 even though the rotary drum 70 rotates at high speed. 
As described above, the present invention elastically supports a rotary 
head cylinder with respect to a drum base along the rotational axis, to 
thereby prevent an axial vibration generated by rotation of a rotary drum. 
Thus, when the present invention can be applied to a camcorder, a problem 
that noise is mixed with a recording signal can be prevented. Also,. an 
assembly work is simplified and facilitated by fixing a rotary head 
cylinder to a drum base, using protrusions formed on the drum base and 
insertion holes formed on a static drum. 
While only certain embodiments of the invention have been specifically 
described herein, it will be apparent that numerous modifications may be 
made thereto without departing from the spirit and scope of the invention.