JPH04305814A - Rotary head drum device - Google Patents

Abstract

PURPOSE:To dispense with a drum supporter, to enable an upper drum to be positioned at the upper part of a fixed shaft with high precision and to improve the relative positioning precision of the upper, inner and lower drums. CONSTITUTION:A lower drum 10 in which a fixed shaft 11 is erected and fixed perpendicularly, an inner drum 20 on the outer periphery plane 20a of which a video head 21 is protruded and supported rotatably freely with the middle way part 11b of the fixed shaft 11 via a pair of ball bearings 22, 22, etc., an upper drum 30 fixed on the upper terminal part 11c of the fixed shaft 11, and a motor 40 consisting of a rotor 41 fixed on the inner drum 20 and a stator 41 fixed on the upper drum 30 and confronting with the rotor 41 and the upper drum 30 is fixed by inserting with pressure the hole 30b of the upper drum 30 into the upper terminal part 11c of the fixed shaft 11.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helical scan type rotary head drum device having a built-in motor between an upper drum and a middle drum.

0002

2. Description of the Related Art In a VTR (video tape recorder) as a magnetic recording and reproducing device, a rotating drum having a video head for recording video signals is arranged at a slight angle with respect to the running direction of the tape, and is rotated so as to diagonally move the drum onto the tape. A helical scan type rotary head drum device is used that records in a pattern of: To explain this in detail with reference to FIG. 4, reference numeral 100 is a rotary head drum device, which is used in a VTR capable of magnetic recording and reproduction. This rotary head drum device 100 has a middle drum (both not shown) which has a video head between a lower drum 101 and an upper drum 102 and is rotatably supported. Both the lower drum 101 and the upper drum 102 are fixed drums, so the drum support 103 is used to keep the distance between the two drums 101 and 102 constant.
, 102. Further, a motor 104 consisting of a stator 105 and a rotor 106 for rotating the middle drum is detachably attached to the lower surface of the lower drum 101 with screws 107. This middle drum is driven by the motor 104
The rotor 106 is connected to a rotating shaft 106a of a rotor 106 for rotation.

0003

However, in the conventional rotary head drum device 100, since the shaft for rotating the middle drum having the video head is the rotary shaft 106a of the rotor 106, the upper drum 102 and the lower drum 101
A drum support 103 for positioning and fixing the drums at a predetermined gap is essential, and the overall weight becomes heavy and large, and the upper drum 10 relative to the lower drum 101
2, positioning is complicated, and it is difficult to position and fix with high precision.

SUMMARY OF THE INVENTION Accordingly, the present invention provides a high-precision rotary head drum device that does not require a drum support and can be made smaller and lighter.

[0005]

[Means for Solving the Problems] A lower drum having a vertically fixed shaft, a middle drum having a head protruding from its outer peripheral surface and rotatably supported via a bearing in the middle of the shaft, and the shaft. A motor includes an upper drum fixed to an upper end, a rotor fixed to the middle drum, and a stator fixed to the upper drum and facing the rotor, the upper drum being fixed to the upper end of the shaft. It is fixed by press fitting.

[0006]

[Function] A motor for rotating the middle drum having a head is built in between the middle drum and the upper drum, and the shaft that rotatably supports the middle drum is a fixed shaft fixed to the lower drum. This eliminates the need for a drum support, reduces the number of parts, and makes the entire device smaller and lighter. Further, since the upper drum is fixed to the upper end of the shaft by press fitting, the upper drum can be easily positioned and fixed to the shaft with high precision, and the relative positional precision of each drum is increased, thereby improving the precision of the entire device.

[0007]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a helical scan type rotary head drum device, which is used in an 8 mm VTR as a magnetic recording/reproducing device. This rotary head drum device 1 includes a lower drum (fixed drum) 10 in which a cylindrical fixed shaft 11 is press-fitted into a hole 10b formed in the center of a bottom portion 10a so as to stand vertically, and an outer peripheral surface 20a. A middle drum (rotating drum) 20, which is rotatably supported via a pair of ball bearings 22, 22 fitted to the middle part 11b of the fixed shaft 11 with the video head 21 protruding, and an upper part 30a. An upper drum (fixed drum) 30 is fixed to the upper end 11c of the fixed shaft 11 by press fitting or the like into a hole 30b formed in the center of A coreless motor 40 is fixed to the drum 10 and consists of a stator 45 facing each other with a predetermined clearance between the magnet 42 of the rotor 41 and the back yoke 43, and a video signal is sent to the video head 21 which is rotating during recording. transformers 51 on the rotor side attached to the middle drum 20 and on the stator side attached to the lower drum 10, which supply the signal and take out the playback signal during playback;
52, and a rotary transformer 50.

The lower drum 10 is formed into a cylindrical shape with a bottom, and a tape lead 10c for guiding a magnetic tape (not shown) is formed on its outer peripheral surface 10d. The rotary transformer 52 on the stator side is attached to the upper surface of the bottom portion 10a of the lower drum 10. Further, a flexible substrate 13 for a rotary transformer (video head) signal line is fixed to the bottom surface of the bottom portion 10a of the lower drum 10 via a plurality of pins and a terminal plate 12 (not shown). The magnetic tape is attached to the outer peripheral surface 10d of the lower drum 10 and the middle drum 2.
0, the video head 21, and the outer peripheral surface 30d of the upper drum 30, respectively.

The middle drum 20 is formed into a thick disk shape, and the pair of ball bearings 22,
The substantially cylindrical flange 23 is fitted onto the outer circumferential surface of the flange 22 , and is fitted into the middle of the flange 23 so as to be rotatable with respect to the fixed shaft 11 . A lower part of the outer peripheral surface 20a of the middle drum 20 is connected to the outer peripheral surface 10d of the lower drum 10 and the upper drum 3.
It is exposed on the same plane between the outer peripheral surfaces 30d of 0. On the lower surface of the flange 23 is a rotating transformer 5 on the rotor side.
1 is bonded with adhesive, and faces the rotary transformer 52 on the stator side with a predetermined clearance therebetween. Also, a recess 2 formed on the bottom side of the middle drum 20
A base 25 is fixed to 0b via bolts 24. The video head 21 is fixed to this base 25 by soldering or the like. The height of this base 25 is adjustable by means of a push screw 26. The video head 21 and the rotor-side rotary transformer 51 are connected to each other via an elastically deformable substantially U-shaped spring plate-like contact 28 of a terminal plate 27 attached to the upper surface of the rotor-side rotary transformer 51.
is electrically connected to. A compression coil spring 29 is interposed on the fixed shaft 11 between the pair of ball bearings 22, 22 to prevent each ball bearing 22 from wobbling with respect to the fixed shaft 11.

The upper drum 30 is formed into a cylindrical shape with an upper part 30a closed, and the lower surface side of the upper part 30 has a circular recess 30c. The upper part 3 of this upper drum 30
When the hole 30b of 0a is press-fitted into the upper end 11c of the fixed shaft 11, the upper surface of the recess 30c is press-fitted into the upper end 11c of the fixed shaft 11, and the annular plate-shaped flange 1 is fixed.
4, the hole 30b is fitted into the outer peripheral surface of the upper end 11c of the fixed shaft 11, and the upper drum 30 is positioned and fixed to the upper end 11c of the fixed shaft 11 with high precision. Thereafter, the upper drum 30 and the flange 14 are fastened and fixed by bolts 31 screwed into the screw holes 14a of the flange 14.

Further, the rotor 41 of the motor 40 is formed into a dish shape, and is fixed to the middle drum 20 with bolts 44. An annular plate-shaped magnet 42 is fixed onto the rotor 41. Further, an outer peripheral portion 45a of the stator (yoke) 45 of the motor 40 is fixed to a stepped portion 30e formed on the inner peripheral surface side of the upper drum 30 with an adhesive. A multi-phase coil 46 attached to the lower surface of the stator 45 is attached to the magnet 42 of the rotor 41.
They are facing each other with a predetermined clearance between them. Further, the back yoke 43 of the rotor 41 is attached to the upper part of the flange 23 (the upper part of the rotor 41) via a back yoke support 47 that is press-fitted into the upper part of the flange 23. The back yoke 43 is made of a three-layer vibration damping material in which resin is sandwiched between metal plates. Further, the back yoke support 47 is made of polyester elastomer resin, rubber, or the like, which has a high vibration damping effect. These back yokes 4
3. How to install the stator 45 is to install the back yoke 43 and back yoke support 4 with the upper drum 30 upright.
7 is placed in the upper drum 30, and then the outer peripheral portion 45a of the stator 45 is adhered to the stepped portion 30e of the upper drum 30 with adhesive. As a result, the upper drum 3
The upper drum 30 housing the back yoke 43 with the back yoke support 47 attached between the stator 45 and the stator 45 is made into a unit in advance. By assembling the lower drum 10 in which the fixed shaft 11 stands vertically, the middle drum 20 in which the rotor 41 of the motor 40 is incorporated, and the unitized upper drum 30 in order, a high-precision rotating head drum device is created. 1 can be assembled easily and in a short time. Incidentally, wiring such as a harness used for the motor 40 is brought out through a window hole or a notch (both not shown) formed in the upper part 30a of the upper drum 30 and connected to the outside.

According to the rotary head drum device 1 of the above embodiment, the fixed shaft 11 that rotatably supports the middle drum 20 having the video head 21 protruding from the outer circumferential surface 20a is erected and fixed at the center of the lower drum 10. Middle drum 20 and upper drum 3
Since the middle drum 20 is made rotatable by the motor 40 built in between the two shafts through the ball bearings 22, 22 fitted to the fixed shaft 11, the rotary head drum device 1 can be made small and compact.
It can be made thinner. In addition, as mentioned above, since the shaft that rotatably supports the middle drum 20 is the fixed shaft 11 fixed to the lower drum 10, there is no need for a conventional drum support, and the cost of the entire rotary head drum device 1 can be reduced. In addition, the weight of the entire device can be further reduced.

Furthermore, since the outer peripheral portion 45a of the stator 45 of the motor 40 is fixed to the stepped portion 30e of the upper drum 30 with adhesive, the rigidity of the stator 45 is increased and the motor 4
The vibration of the stator 45 caused by the rotation of the rotor 41 at zero is damped. In addition, the back yoke 43 that rotates together with the rotor 41 is formed of a damping material with a resin plate sandwiched between steel plates, and a back yoke support 47 that supports this back yoke 43
Since the back yoke 43 is made of a material with high vibration damping properties such as polyester elastomer, vibrations of the back yoke 43 can also be damped. As a result, when the motor 40 rotates, the vibrations of the stator 45 and the back yoke 43 can be suppressed compared to conventional ones, and the electromagnetic noise of the motor 40 caused by these vibrations can be suppressed. The figure compares the electromagnetic sound and vibration characteristics of the conventional rotary head drum device 100 (indicated by A in FIG. 2) and the electromagnetic sound and vibration characteristics (indicated by B in FIG. 2) of the rotary head drum device 1 of the embodiment. Shown in 2. As shown in this figure, the rotation speed of each motor is from 2700 rpm to 900 rpm.
Approximately 5d faster than the conventional model until the high speed of 0 rpm
It can be seen that the B vibration etc. can be attenuated. Therefore, if the present rotary head drum device 1 is employed in a rotary head drum such as a digital VTR that requires high-speed rotation, electromagnetic noise and vibration can be reduced.

Furthermore, the upper drum 30 has holes 30
b is press-fitted into the upper end portion 11c of the fixed shaft 11, and fastened and fixed to the fixed shaft 11 via a bolt 31 that is screwed into the threaded hole 14a of the flange 14, which is press-fitted into the upper part of the fixed shaft 11 and fixed. Therefore, the upper drum 30 can be positioned and fixed with high precision via the upper surface of the flange 14 and the upper end portion 11c of the fixed shaft 11. Thereby, the deviation of the outer circumferential surface 30d of the upper drum 30 with respect to the outer circumferential surface 10d of the lower drum 10 and the outer circumferential surface 20a of the middle drum 20 can be made 1 μm or less. Further, since the screw hole 14a of the flange 14 into which the bolt 31 is screwed is not a through hole, metal powder etc. do not fall into the drum when the bolt is fastened, and the rotating head drum device 1 has high reliability.
can be provided.

FIG. 3 shows another embodiment of a rotary head drum device 1'. The middle drum 20' of this rotary head drum device 1' is formed into a cylindrical shape with a bottom, and is of a so-called upper rotating drum type in which the magnetic tape contacts the outer circumferential surface 20a of the inner drum 20' and the outer circumferential surface 10d of the lower drum 10. Further, the length of the outer circumferential surface of the upper drum 30' of the rotary head drum device 1' is up to the stepped portion 30e that fixes the outer circumferential portion 45a of the stator 45 of the motor 40, and the other configuration is the same as that of the above embodiment. Since they are similar, the same reference numerals are given and the explanation will be omitted. With this configuration, the lower drum 10 of the above embodiment
In addition to being able to share the same fixed shaft 11, the same functions and effects as in the previous embodiment can be achieved.

According to each of the embodiments described above, the flange 14 is fixed to the upper end 11c of the fixed shaft 11 by press fitting.
An annular plate-shaped flange may be integrally formed to protrude from the upper end of the fixed shaft 11 to form a flange. Furthermore, it goes without saying that the rotary head drum device can be applied to a so-called propeller-rotated drum in which the middle drum is made of a thin-walled disk.

[0018]

As described above, according to the rotary head drum device of the present invention, a motor for rotating the middle drum having a head is built in between the middle drum and the upper drum, and
Since the shaft that rotatably supports the middle drum is a fixed shaft fixed to the lower drum, there is no need for a conventional drum support, which reduces the number of parts and makes the entire device smaller and lighter. can. In addition, since the upper drum is fixed to the upper end of the shaft by press fitting, the upper drum can be easily positioned and fixed on the shaft with high precision, increasing the relative positional accuracy of each drum and improving the accuracy of the entire device. can be further improved.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a rotary head drum device showing an embodiment of the present invention.

FIG. 2 is a characteristic explanatory diagram comparing the electromagnetic sound and vibration of the above rotary head drum device and a conventional rotary head drum device.

FIG. 3 is a sectional view of a rotary head drum device according to another embodiment.

FIG. 4 is an exploded perspective view of a conventional rotary head drum device.

[Explanation of symbols]

1, 1'... Rotating head drum device, 10... Lower drum, 1
1...shaft, 11b...middle part, 11c...upper end part, 20, 20
'... Middle drum, 21... Head, 22... Ball bearing (bearing), 30, 30'... Upper drum, 40... Motor, 4
1...Rotor, 45...Stator.

Claims (1)

[Claims] [Claim 1] A lower drum having a vertically fixed shaft;
a middle drum with a head protruding from the outer circumferential surface and rotatably supported via a bearing in the middle of the shaft; an upper drum fixed to the upper end of the shaft; a rotor fixed to the middle drum; A rotary head drum device comprising: a motor consisting of a stator fixed to the upper drum and facing the rotor; and the upper drum is fixed to the upper end of the shaft by press fitting.