JPH0512769A - Rotary head drum device - Google Patents

Abstract

PURPOSE:To improve head contact even when the rotary head drum device is reduced in size by decreasing each drum diameter and increasing the opposition area between a rotary drum and an upper fixed drum, forming air blowout grooves in at least one surface, and forming air film between a tape travel surface of each drum and a tape. CONSTITUTION:Even when the drums 10, 30, and 40 which constitute the rotary head drum device 1 are reduced in diameter and the peripheral wall part of the lower fixed drum 10 is made thin, the mutually opposite top surface 30b and reverse surface 40b of the rotary drum 30 and upper fixed drum 40 can be made conic and inversely conic to increase an area. Consequently, the respective air blowout grooves 36 can be formed in the top surface 30b of the drum 30 and the air film with proper and uniform layer thickness can be formed between the tape travel surfaces of the respective drums 10, 30, and 40 and the magnetic tape with air blow out of them. The tape is therefore not damaged and even when the device is reduced in size, the heat contact is sufficiently secured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary head drum device suitable for use in, for example, a VTR (video tape recorder).

[0002]

2. Description of the Related Art In a VTR (video tape recorder) as a magnetic recording / reproducing apparatus, a rotary drum having a head for recording / reproducing a video signal is arranged at a slight inclination from the tape running direction, and is rotated on the magnetic tape. In addition, a rotary scan type rotary head drum device for recording in an oblique pattern is used. This will be briefly described with reference to FIGS. 6 to 8. In the figure, reference numeral 100 denotes a helical scan type rotary head drum device, and a fixed drum 110 having a tape lead portion 110b formed on an outer peripheral surface 110a, and a fixed drum 110 on the fixed drum 110. The rotary drum 120 is rotatably supported via a rotary shaft (not shown), and is generally constituted by a rotary drum 120 having a head 101 protruding from an outer peripheral surface 120a. Then, as shown in FIG. 6, the air a entrained from the tape inlet side A of each drum 110, 120 by the rotation of the rotary drum 120 becomes the outer peripheral surface 110a, 120a of each drum 110, 120 and the magnetic tape T. By interposing between the outer peripheral surfaces 110a, 1 of the respective drums 110, 120
Between the 20a and the magnetic tape T, a layer of air called "air film" is generated. With this air film, the outer peripheral surfaces 110a, 120 of the respective drums 110, 120
The magnetic tape T does not come into violent contact with the magnetic tape T and the magnetic tape T does not contact the outer peripheral surfaces 110a, 1 of the drums 110, 120 respectively.
The tape travels around 20a.

However, as shown in FIGS. 6 and 7, the thickness of the air layer (t
_A ) is too thick, the contact between the magnetic tape T and the head 101 is obstructed, the head contact of the magnetic tape T is deteriorated, and, as shown in FIGS. The layer thickness (t _B ) becomes too thin, and the magnetic tape T is violently in contact with the outer peripheral surfaces 110a and 120a of the drums 110 and 120, resulting in large tape damage.

In order to cope with this, as shown in FIGS. 9 and 10, the lower end surface 120c of the peripheral wall portion of the cylindrical rotary drum 120, the upper portion of which is closed, faces the fixed drum 110.
A plurality of spiral air-blowing grooves 121 are formed on the respective tapes, and the air film is properly and evenly distributed over the entire circumference of the tape wrap surface (hereinafter, referred to as tape running surface) of the outer peripheral surfaces 110a and 120a of the respective drums 110 and 120. Have been devised to generate. In this case, the gap between the fixed drum 110 and the rotating drum 120 is made sufficiently small. Then, when the rotating drum 120 is rotated, air is forced out of the gap through the air blowing grooves 121 to the outside by the pressure generated by the viscosity of air, and the air blows the magnetic tape T to each drum. The tape is made to float above the tape running surface of 110 and 120.

[0005]

However, as the entire rotary head drum device 100 becomes smaller, the lower end surface 1
Rotating drum 1 which forms air blowing groove 121 in 20c
When the diameter of 20 is reduced, the thickness of the peripheral wall portion of the rotary drum 120 is reduced, so that the width of the lower end surface 120c forming the air blowing groove 121 is significantly narrowed. Even if the air blow-out groove 121 can be formed on the remarkably narrowed lower end surface 120c, the magnetic tape T is attached to each of the drums 110, 1.
There is a possibility that an air film having a sufficient layer thickness to be floated from the tape running surface of 20 cannot be produced.

Therefore, according to the present invention, even if the diameter of the drum is reduced, an air film having a proper and uniform layer thickness can be easily formed between the tape running surface of each drum and the tape. (EN) A rotary head drum device capable of preventing damage and ensuring good head contact of a tape.

[0007]

A lower fixed drum having a shaft vertically erected and fixed, a bearing housing rotatably supported at a midway part of the shaft through a bearing, and a head protruding a predetermined amount from an outer peripheral surface. A fixed upper drum fixed to the upper part of the bearing housing, a fixed upper drum fixed to the upper end of the shaft and facing the rotary drum with a predetermined clearance, a rotor fixed to the lower part of the bearing housing, and A motor comprising a stator fixed to the fixed lower drum and facing the rotor, and at least one surface of each of the facing surfaces of the rotary drum and the fixed upper drum,
An air blowing groove is formed.

[0008]

With the miniaturization of the rotary head drum device as a whole, even if the diameter of each drum is reduced, the areas of the surfaces of the rotary drum and the fixed upper drum that face each other can be made large, so that they are formed on at least one of these surfaces. By the air blowing groove, an air film having a proper and uniform layer thickness is easily formed between the tape running surface of each drum and the tape, and the tape damage is prevented. Further, since an air film having a proper and uniform layer thickness is formed between the tape running surface of each drum and the tape, good head contact of the tape is secured.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a rotary scan type rotary head drum device, which is used for an 8 mm VTR as a magnetic recording / reproducing device. This rotary head drum device 1 includes a fixed lower drum 10 in which a lower end 11a of a cylindrical fixed shaft 11 is fixed by a press fit into a hole 10b formed in the center of a bottom 10a so as to stand vertically.
A cylindrical bearing housing 20 rotatably supported on the intermediate portion 11b of the fixed shaft 11 via a pair of ball bearings 28, 28, and a head 31 projecting from the outer peripheral surface 30a by a predetermined amount. A rotary drum 30 fixed to the upper part of the bearing housing 20, a fixed upper drum 40 fixed to the upper end 11c of the fixed shaft 11 and facing the rotary drum 30 with a predetermined clearance, and a lower part of the bearing housing 20. A rotor 51 fixed to
A coreless motor 50, which is fixed to the fixed lower drum 10 and includes a stator 56 facing the magnet 53 of the rotor 51 and a back yoke 54 with a predetermined clearance (each about 0.3 mm), and rotates during recording. The bearing housing 2 for supplying a video signal to the above-mentioned head 31 and taking out a reproduction signal at the time of reproduction.
The rotary transformer 60 is composed of a rotor side mounted on the lower surface side of No. 0 and a stator side transformer 61, 62 mounted on the upper surface side of the bottom portion 10a of the fixed lower drum 10.

The fixed lower drum 10 is formed in a cylindrical shape having a bottom, and a tape lead portion 10c for guiding a magnetic tape (not shown) is formed on the outer peripheral surface 10d thereof. The rotary transformer 62 on the stator side is bonded and fixed to the upper surface of the bottom portion 10a of the fixed lower drum 10. Further, on the bottom surface of the bottom portion 10a of the fixed lower drum 10, a flexible substrate (not shown) for external connection of the rotary transformer 62 on the stator side is attached via a plurality of pins and a terminal plate.

As shown in FIGS. 1 and 3, upper and lower flanges 21 and 22 are integrally formed on the upper and lower portions of the bearing housing 20 so as to project therefrom. The upper flange 21 has a pair of substantially fan-shaped projecting portions, and female screw holes 23 for fastening and fixing the rotary drum 30 are formed at the centers of the respective projecting portions. The outer peripheral surface 20 a above the upper flange 21 is attached to the upper drum 21 by the rotary drum 30.
It is a centering reference plane that determines the radial position when mounting. A pair of insertion holes 24, 24 are formed in the upper flange 21 so as to sandwich the female screw holes 23. The lower flange 22 is formed in a disk shape so as to project integrally, and a pair of female screw holes 25, 25 for fastening and fixing the rotor 51 are formed at positions 90 ° apart from the positions of the female screw holes 23. There is. The outer peripheral surface 22a of the lower flange 22 serves as a centering reference surface that determines the radial position of the rotor 51 when the rotor 51 is mounted on the lower flange 22. Further, three insertion holes 26 are formed between the pair of female screw holes 25, 25 of the lower flange 22, respectively, and the notches 27 are formed on the lower side thereof.
Has been formed. A compression coil spring 29 is interposed between the pair of ball bearings 28, 28 fitted in the bearing housing 20, and the pair of ball bearings 28, 28 is loose relative to the fixed shaft 11. There is no such thing.

The rotary drum 30 has a conical surface projecting in a stepped manner on the upper surface 30b side and a flat surface on the lower surface 30c side, and a center hole 30d is formed in the center thereof. is there. The center hole 30d of the rotary drum 30 is provided on the outer peripheral surface 20a of the bearing housing 20.
The lower surface 30c around the center hole 30d.
Is mounted on the upper flange 21 of the bearing housing 20. Then, the rotary drum 30 and the upper flange 21 of the bearing housing 20 are fastened and fixed to each other via the respective set screws 32 screwed into the female screw holes 23 formed in the upper flange 21. Further, the set screw 3 is provided in the opening recess 30e formed on the lower surface 30c side of the rotary drum 30.
The base portion of the head base 34 is fixed via 3. The head 31 is fixed to the tip end side of the upper surface of the head base 34 with an adhesive or the like. The tip side of the head base 34 is deformable downward by pressing the tip 35a of a push screw 35 as a pairing adjustment screw that is screwed into a female screw hole 30f formed in the rotary drum 30. (Head height adjustment) is available. It should be noted that 30 g in FIGS. 1 and 2 is a notch for inserting the set screw 32 into the head.

Further, a plurality of spiral air blowing grooves 36 are formed on the upper surface 30b of the rotary drum 30. As shown in FIG. 2, each of the air blowing grooves 36 is formed in a spiral shape so as to reach from the inner peripheral edge to the outer peripheral edge of the upper surface 30b, and the groove width is gradually increased from the inner peripheral edge side to the outer peripheral edge side. I am doing it. The groove shape of each air blowing groove 36 has, for example, a depth of 0.1 m.
m, inclination angle 16 °, groove width to hill width ratio 1: 1 of upper surface 30b, gap 0.02 mm between upper surface 30b of rotating drum 30 and lower surface 40b of fixed upper drum 40, which will be described later, and the like. .. Then, when the rotary drum 30 rotates,
Air is blown out of each of the drums 30 and 40 through the gap between the upper surface 30b of the rotary drum 30 and the lower surface 40b of the fixed upper drum 40 by each air blowing groove 36, and an air film having a proper and uniform layer thickness is easily generated. You can do it.

The fixed upper drum 40 is formed in a substantially cylindrical shape in which the upper portion 40a is closed, and the lower surface 40b of the upper portion 40a has an inverted conical surface shape, and a predetermined clearance (for example, on the upper surface 30b of the rotary drum 30). 0.02 mm) facing each other. A center hole 40c formed in the center of the upper portion 40a of the fixed upper drum 40 is press-fitted into the upper end portion 11c of the fixed shaft 11, and the center hole 4c
0c is a flat lower surface on the upper end portion 1 of the fixed shaft 11.
An annular plate-like flange 41 press-fitted and fixed to the lower side of 1c
It is placed in. Then, the fixed upper drum 40 and the flange 41 are fastened and fixed by respective setscrews 42 screwed into a plurality of female screw holes 41a of the flange 41. Further, an operation hole 40e is formed at a position facing the push screw 35 of the rotary drum 30, so that the push screw 35 can be screwed in from the fixed upper drum 40 side. The outer peripheral surface 10d of the fixed lower drum 10, the outer peripheral surface 30a of the rotary drum 30, and the outer peripheral surface 40d of the fixed upper drum 40 are flush with each other.
The outer peripheral surfaces 10d, 30a, 40d of the reference numerals 30, 40 are tape running surfaces of the magnetic tape which are wound around the outer peripheral surfaces 10d, 30a, 40d by a predetermined angle and run.

The rotor 51 of the motor 50 comprises a dish-shaped rotor case 52, an annular plate-shaped magnet 53 fixed to the upper surface of the rotor case 52, and a disk-shaped back yoke 54. It is fastened and fixed to each female screw hole 25 of the lower flange 22 of the bearing housing 20 via a set screw 55. As shown in FIGS. 3 and 4, a mounting hole 52a through which the upper flange 21 of the bearing housing 20 is inserted is formed in the center of the rotor case 52, and an annular recess 52b is formed on the bottom surface thereof. is there.
The peripheral surface 52c of the recess 52b is the bearing housing 20.
As shown in FIG. 4, a pair of lower surfaces 52d, 52d protruding inwardly serve as mounting surfaces, as well as being a reference surface fitted to the centering reference surface 22a of the lower flange 22. A hole portion 52d 'through which the shank portion of each of the set screws 55 is inserted is formed in each mounting surface 52d. Each of the mounting surfaces 52d is a surface that comes into contact with the upper surface of the lower flange 22, and is 50 from the lower surface of the other recess 52b.
There is a height difference of about μm.

The back yoke 54 of the rotor 51 is provided with a pair of back yoke supports 59, 59 provided on the outer peripheral surface 20b between the upper and lower flanges 21, 22 of the bearing housing 20 at an angle of 180 °. Bearing housing 20 so that the gap does not change with reference to 20b.
Installed on. The back yoke 54 is made of a damping material having a three-layer structure in which resin is sandwiched between metal plates. Also,
The back yoke support 59 is made of polyester elastomer resin, rubber or the like having a high vibration damping effect.

The stator 56 of the motor 50 is composed of a disk-shaped stator substrate 57 and a plurality of layers of coil portions 58 and the like provided on the lower surface of the stator substrate 57, and the outer peripheral portion 57a of the stator substrate 57 is formed. The fixed lower drum 10
It is bonded and fixed to the step portion 10e formed in the inner peripheral surface of the peripheral wall portion with an adhesive. The coil portions 58 of the plurality of phases of the stator 56 face the magnet 53 of the rotor 51 with a predetermined clearance (about 0.3 mm).

Further, the rotary transformer 61 on the rotor side is adhered and fixed to the lower surface of the lower flange 22 of the bearing housing 20 with an adhesive or the like.
It faces the rotary transformer 62 on the stator side fixed to the upper surface of the bottom portion 10a with a predetermined gap (for example, 25 μm). Wiring (not shown) of the rotary transformer 61 on the rotor side is connected to the lower flange 22 of the bearing housing 20.
Is connected to a relay board (not shown) arranged on the lower surface 30c of the rotary drum 30 from the notch portion 27 and the respective insertion holes 26 through the respective insertion holes 24 of the upper flange 21, and on the head base 34 via the relay board. Recording / playback head 3
It is connected to 1.

According to the rotary head drum device 1 of the above embodiment, the diameter of each drum 10, 30, 40 is made small (for example, diameter 26.7 mm), and the thickness of the peripheral wall portion of the fixed lower drum 10 is made thin (for example, thin). Even if the width is 0.7 mm), since the upper surface 30b and the lower surface 40b of the rotary drum 30 and the fixed upper drum 40 which face each other can be made into a conical surface shape and an inverted conical surface shape, the respective areas can be made large, Each air blowing groove 36 formed on the upper surface 30b of the rotating drum 30
As a result, an air film having an appropriate and uniform layer thickness can be generated between the tape running surface of each drum 10, 30, 40 and the magnetic tape, and the tape damage can be reliably prevented. Since each of these air blowing grooves 36 is formed from the upper edge to the lower edge of the conical surface 30b of the rotating drum 30, the upper surface 3 of the rotating drum 30 is formed.
0b and the lower surface 40b of the fixed upper drum 40, it is possible to efficiently and easily generate an air film having a proper and uniform layer thickness necessary for floating the magnetic tape. Further, since an air film having an appropriate and uniform layer thickness can be formed between the tape running surface of each of the drums 10.30.40 and the magnetic tape, a good magnetic tape head contact can be secured. it can.

Further, the tip end 35a of the push screw 35 screwed from the upper surface 30b side of the rotary drum 30 constitutes the tip end side of the head base 34 so that it can be pressed and deformed, and the push screw 35 of the fixed upper drum 40 is fixed to the push screw 35. Since the operation hole 40e is formed at the opposite position, the pairing adjustment can be easily performed in the completed state of the rotary head drum device 1. In addition, the rotor case 52 of the rotor 51 of the motor 50
And the like are fastened and fixed to the lower flange 22 of the bearing housing 20 by the setscrews 55 and cannot be directly attached to the rotary drum 30 side. Therefore, when the rotor 51 of the motor 50 is fastened and fixed, the rotary drum 30 is not bent or the like. There is no gap in the pairing.

Further, since the outer peripheral portion 57a of the stator substrate 57 of the stator 56 of the motor 50 is fixed to the step portion 10e of the fixed lower drum 10 with an adhesive or the like, the stator 56
The rigidity of the stator is increased, and the vibration of the stator 56 accompanying the rotation of the rotor 51 of the motor 50 can be damped. In addition, the back yoke 54 that rotates together with the rotor case 52 is formed of a damping material in which a resin plate is sandwiched between steel plates, and the back yoke support 5 that supports the back yoke 54.
Since 9 is formed of a material having high vibration damping property such as polyester elastomer, the vibration of the back yoke 54 can be damped. As a result, when the motor 50 is rotated, vibrations of the stator 56 and the back yoke 54 can be suppressed as compared with the conventional one, and electromagnetic noise of the motor 50 due to these vibrations can be reliably suppressed.

By adopting such a structure of the bearing housing 20 and the motor 50, as shown in FIG. 3, when the motor 50 and the like are assembled, the rotor of the rotor 51 does not hit the upper flange 21 of the bearing housing 20. It can be attached to the lower flange 22 through the case 52, and the upper flange 21 and the magnet 43 can be attached.
Can be made large. Further, when the rotor case 52 of the rotor 51 is attached to the lower flange 22 of the bearing housing 20, the outer peripheral surface 22 of the lower flange 22 is attached.
Since the concave portion 52b formed on the lower surface side of the rotor case 52 is fitted into the rotor case 52 by using a as the centering reference surface, the rotor case 52 can be assembled at low cost and with high accuracy.

The wiring (not shown) extending from the rotary transformer 61 on the rotor side is provided with notches 27 formed in the lower flange 22 of the bearing housing 20 and the insertion holes 2.
6 and the respective through holes 24 formed in the upper flange 21 can be easily routed to the lower surface 30c side of the rotary drum 30. Further, an unillustrated relay board or the like for connecting the rotary transformer 61 and the head 31 via the wiring can be arranged on the rotary drum 30 side, and the overall height of the rotary head drum device 1 can be further suppressed. It is possible,
It is possible to further reduce the thickness and size of the entire device.

According to the above-mentioned embodiment, the spiral air blowing groove is formed on the upper surface 30b of the rotary drum 30, but it faces the upper surface 30b of the rotary drum 30 as in another embodiment shown in FIG. A plurality of spiral air blowing grooves 46 may be formed on the lower surface 40b of the fixed upper drum 40. In this case, as shown in FIG.
A lower surface 40 facing the upper surface 30b of the rotary drum 30.
By reducing the area of the air blowing groove portion of b and increasing the area of the air blowing groove portion of the lower surface 40b of the tape outlet side B, the air blowing amount of the tape inlet side A and the tape outlet side B can be changed. There is. As a result, more air is blown out on the tape outlet side B than on the tape inlet side A, and the layer thickness of the air film is made more uniform over the entire tape running surface.

In the above embodiment, the air blowing groove is formed on the upper surface side of the rotary drum, but it may be formed on both the upper surface of the rotary drum and the lower surface of the fixed upper drum. Furthermore, in the above-described embodiment, the rotary head drum device of which the rotary drum is the medium drum rotary type has been described, but it goes without saying that the rotary drum can be applied to a so-called propeller rotary type rotary head drum device in which the rotary drum is a thin disk.

[0027]

As described above, according to the rotary head drum device of the present invention, even if the diameter of each drum is reduced in accordance with the downsizing of the entire device, the surfaces of the rotary drum and the fixed upper drum which face each other. Since it is possible to take a large area, the air blowing groove formed on this at least one surface,
An air film having a proper and uniform layer thickness can be easily formed between the tape running surface of each drum and the tape, and the tape damage can be prevented. Further, since an air film having a proper and uniform layer thickness can be formed between the tape running surface of each drum and the tape, a good tape head contact can be secured.

[Brief description 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 perspective view of a rotary drum used in the rotary head drum device.

FIG. 3 is an exploded perspective view showing a relationship between a rotor of a motor used in the rotary head drum device and a bearing housing.

FIG. 4 is a perspective view of the rotor seen from the bottom side.

FIG. 5 is a schematic explanatory view of an air blowing groove of another aspect formed in the fixed upper drum used in the rotary head drum device.

FIG. 6 is a schematic plan view of a conventional rotary head drum device.

FIG. 7 is a schematic side view of the conventional rotary head drum device on the tape entrance side.

FIG. 8 is a schematic side view on the tape outlet side of the conventional rotary head drum device.

FIG. 9 is a perspective view of another conventional rotary head drum device.

FIG. 10 is a perspective view of a rotary drum used in the other conventional rotary head drum device as viewed from the bottom side.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rotary head drum device, 10 ... Fixed lower drum, 11
... shaft, 11b ... midway part, 11c ... upper end part, 20 ... bearing housing, 28 ... ball bearing (bearing), 30 ... rotary drum, 30a ... outer peripheral surface, 30b ... upper surface (surface facing lower surface of fixed upper drum) , 31 ... Head, 36 ... Air blowing groove, 40 ... Fixed upper drum, 40b ... Lower surface (surface facing upper surface of rotating drum), 46 ... Air blowing groove, 5
0 ... Motor, 51 ... Rotor, 56 ... Stator.

Claims (1)

Claim: What is claimed is: 1. A fixed lower drum having a shaft vertically erected and fixed, a bearing housing rotatably supported in the middle of the shaft through a bearing, and a head having a predetermined amount on the outer peripheral surface. A rotary drum that is projected and fixed to the upper part of the bearing housing, a fixed upper drum that is fixed to the upper end of the shaft and faces the rotary drum with a predetermined clearance, and a rotor that is fixed to the lower part of the bearing housing. And a motor comprising a stator fixed to the fixed lower drum and facing the rotor, and an air blowing groove is formed on at least one surface of the rotary drum and the fixed upper drum facing each other. A rotary head drum device.