JPH06338108A - Rotary magnetic head device and manufacture of drum of the rotary magnetic head device - Google Patents

Abstract

(57) [Abstract] [Purpose] A rotary magnetic head device for improving track straightness of the magnetic tape and a contact property of the magnetic head against the magnetic tape, and a rotary magnetic head for reducing the cost of the rotary magnetic head device. To provide a method for manufacturing a drum of an apparatus. [Structure] The rotary magnetic head device 1 includes a bearing holder 2
1 and a rotating drum 35 rotatably supported by the bearing holder 21. The center M of the fixed drum 11 corresponds to the uneven distribution of the air film A generated between the rotating peripheral surface of the rotating drum 35 and the traveling magnetic tape 200.
It is eccentric from the rotation center L of.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary magnetic head device used in a VTR, a DAT or the like and a method for manufacturing a drum of the rotary magnetic head device.

[0002]

2. Description of the Related Art Conventionally, a rotary magnetic head device of this type is
For example, the configuration is as shown in FIG. In the figure, the rotary magnetic head device 100 is shown as a fixed drum 110.
And the bearing holder 1 assembled in the fixed drum 110.
20 and the bearing holder 120, the fixed drum 1
A rotation shaft 130 rotatably supported around the center of
And the rotary drum 14 fixed to the upper end of the rotary shaft 130.
0 and a motor unit 150 attached to the lower side of the bearing holder 120 for rotating the rotary shaft 130 at high speed.

As a result, the magnetic tape 200 is run obliquely along the tape guide groove 113 of the fixed drum 110, and the magnetic head 143 of the rotating drum 140 helically scans the tape 200, thereby recording / reading information. It is designed to do.

[0004]

However, such a rotary magnetic head device 100 has the following problems. As shown in FIG. 5, when the rotary drum 140 is rotated at a high speed, the rotary drum 140 entrains air, and an air film A is generated between the peripheral surface of the rotary drum 140 and the magnetic tape 200. The air film A has a low tape tension and is distributed thickly on the S side where the surface in contact with the rotating drum 140 is large, and is thin on the T side where the tape tension is high and the surface in contact with the rotating drum 140 is small.

Therefore, the running center P of the magnetic tape 200 is
1 is eccentric from the running portion center P2 of the fixed drum 110 by the difference in the amount of the air film A. As a result, the magnetic tape 200 may be released from the tape guide groove 113, and the track linearity of the magnetic tape 200 recorded at this time may deteriorate.

Even if the magnetic tape 200 recorded by another device is reproduced by the rotary magnetic head device 100, reproduction output may not be obtained.

Further, the shape of the running magnetic tape 200 in the width direction is also different between the S side and the T side, which causes spacing loss, and also has a bad influence on the contact characteristics between the magnetic tape 200 and the magnetic head 143. Was being given.

In the conventional rotary magnetic head device 100, the fixed drum 110 and the bearing holder 120 are separately formed, and the bearing holder 120 is provided inside the fixed drum 110.
Since it is configured to incorporate, the number of manufacturing processes increases,
As a result, there is also a problem that the product cost increases.

The present invention has been made to solve the above problems, and a rotary magnetic head device and a rotary magnetic head device for improving the track straightness of a magnetic tape and the contact characteristics of the magnetic head against the magnetic tape. It is an object of the present invention to provide a method for manufacturing a drum of a rotary magnetic head device, which reduces the cost.

[0010]

According to the present invention, there is provided a rotary magnetic head device comprising: a fixed drum having a bearing holder; and a rotary drum rotatably supported by the bearing holder. The center of the fixed drum corresponds to the uneven distribution of the air film generated between the rotating peripheral surface of the rotating drum and the traveling magnetic tape,
This is achieved by a rotary magnetic head device that is eccentric from the center of rotation of the rotary drum.

The center of the fixed drum may be eccentric from the center of rotation of the rotary drum so that the center of rotation of the magnetic tape substantially coincides with the center of rotation of the magnetic tape.

Further, the fixed drum may be formed separately from the bearing holder, and the fixed drum may be assembled to the bearing holder with the center thereof being eccentric from the rotation center of the rotary drum. .

Further, in the method of manufacturing a rotary magnetic head device having a rotary drum and a fixed drum, a center hole having a predetermined shape is formed at the center of the workpiece, and the periphery of the center hole is ground into a substantially cylindrical shape. A bearing holder for rotatably supporting the rotating shaft of the rotary drum is machined, and the outer peripheral surface of the workpiece on which the bearing holder is machined is cut into a circular shape and protrudes to the outer peripheral surface. It is achieved by a method for manufacturing a drum of a magnetic transfer head device, in which a tape guide groove is cut and formed to form a fixed drum integral with the bearing holder.

Further, the fixed drum is so arranged that its center is eccentric by a predetermined distance from the center of the bearing holder.
It can be configured to be processed and formed.

[0015]

According to the above construction, even if an air film is generated between the peripheral surface of the rotary drum and the magnetic tape and the air film is unevenly distributed, the center of the fixed drum is unevenly distributed. Corresponding to the above, since the center of rotation of the rotary drum is eccentric, the running center of the magnetic tape is hardly eccentric from the center of the fixed drum.

In particular, by eccentric the center of the fixed drum from the center of rotation of the rotary drum so as to substantially coincide with the center of rotation of the magnetic tape, the magnetic tape can be run without being separated from the fixed drum.

Further, according to the drum manufacturing method of the rotary magnetic head device of the present invention having the above-mentioned structure, the fixed drum integrated with the bearing holder can be processed and formed. The bearing holder is automatically installed just by installing it.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the examples described below are suitable specific examples of the present invention, and therefore, various technically preferable limitations are given, but the scope of the present invention particularly limits the present invention in the following description. Unless otherwise stated, the present invention is not limited to these modes.

FIG. 1 is a sectional view showing a rotary magnetic head device according to an embodiment of the present invention, and FIG. 2 is a schematic plan view showing an eccentric state of a fixed drum.

In FIG. 1, the rotary magnetic head device 1 is
Fixed drum unit 10, rotating drum unit 30, and motor unit 5
It is composed of 0 and.

The fixed drum portion 10 has a structure in which the fixed drum 11 is assembled to the bearing holder 21.

The fixed drum 11 has a cylindrical shape having a large diameter hole 12 in the center thereof, and a tape guide groove 14 which is inclined downward along the peripheral surface is provided on the peripheral surface thereof. .
As a result, the magnetic tape 200 runs obliquely along the tape running surface 15 above the tape guide groove 14. The fixed drum 11 is eccentrically mounted on a separate bearing holder 21.

Specifically, the fixed drum 11 is fitted to the lower side of the bearing holder 21 through the hole 12, and the center thereof is decentered from the central axis L of the bearing holder 21 in the left direction in the figure, It is fixed to the flange portion 22 of the bearing holder 21 with screws 18.

That is, as shown in FIG. 2, the center M of the fixed drum 11 corresponds to the uneven distribution of the air film A generated between the rotating peripheral surface of the rotating drum 35 and the running magnetic tape 200, which will be described later. And is eccentric from the rotation center L of the rotary drum 35 (for example, 5 μm to 1 μm from the rotation center L).
5 μm). Specifically, so that the center M of the fixed drum 11 coincides with the center of curvature of the traveling magnetic tape 200,
The fixed drum 11 is attached to the bearing holder 21.

As shown in FIG. 1, the bearing holder 21 has bearings 23 and 24 at the upper and lower ends of the hollow portion, and the rotary drum portion 30 is rotatably supported by the bearings 23 and 24. .

The rotary drum portion 30 is fixed to a rotary shaft 31 via a flange 32. The rotary shaft 31 has its central axis aligned with the central axis L of the bearing holder 21 and bearings 23, 24. It is rotatably supported by. The rotary drum 3 is attached to the upper end of the rotary shaft 31.
5 is attached via a boss 32.

A magnetic head 38 for recording / reading information to / from the magnetic tape 200 is attached and fixed to a predetermined position on the lower surface of the rotary drum 35 with a screw. Reference numerals 40 and 41 are rotary transformers.

The rotary drum section 30 is driven and rotated by the motor section 50. That is, the stator coil 52 fixed to the lower side of the bearing holder 21 via the motor stator 51 and the rotor magnet 57 fixed to the rotor 55 attached to the lower end of the rotary shaft 31 are magnetically interacted with each other to rotate. Axis 31
Is designed to rotate.

Next, the operation of the rotary magnetic head device 1 will be described. When the motor unit 50 is driven and the rotary drum 35 is rotated at a high speed via the rotary shaft 31, the magnetic tape 200 running diagonally on the tape running surface 15 along the tape guide groove 14 of the fixed drum 11, Magnetic head 3
8 records and reads information.

At this time, since the rotary shaft 31 is rotating at a high speed, the air film A is generated between the magnetic tape 200 and the peripheral surface of the rotary drum 35 as shown in FIG. The amount of the air film A is determined by the width and thickness of the magnetic tape 200, the surface width of the rotating drum 35 with respect to the magnetic tape 200, the number of rotations, the drum diameter, the tape tension, and the like. In one example, the distribution of the air film A is biased at a rate of about 20 to 30 μm on the S side and about 5 to 10 μm on the T side. Therefore, when such an air film A is generated, the center of curvature of the traveling magnetic tape 200 deviates from the center L of rotation of the rotary drum 35.

However, since the center M of the fixed drum 11 is attached to the bearing holder 21 so as to match the center of curvature of the magnetic tape 200, the peripheral surface of the fixed drum 11 corresponds to the deviation of the air film distribution. Then, it approaches the magnetic tape 200 side. Therefore, the magnetic tape 200
Travels along the tape guide groove 14 in a state of being substantially in contact with the tape running surface 15 and is not separated from the tape guide groove 14.

Therefore, the track linearity of the magnetic tape 200 recorded at this time is remarkably improved as compared with the conventional rotary magnetic head device described above. Further, the magnetic tape 200 recorded by another device is used as the rotary magnetic head device 1 of this embodiment.
It is also possible to play with. Further, since the running magnetic tape 200 has a uniform shape in the width direction, spacing loss does not occur, and the magnetic tape 200 and the magnetic head 3 are not generated.
The hit property with 8 is also improved.

In this embodiment, the fixed drum 11 is
Although it is fixed to the flange portion 22 of the bearing holder 21 with the screw 18, the fixed drum 11 may be fixed to the flange portion 22 of the bearing holder 21 by bonding or caulking.

The rotary transformer 41 and the motor stator 51 are preferably attached to the bearing holder 21 in order to align the rotation centers of the rotary transformer 40 and the rotor magnet 57.

Next, a method of manufacturing the drum of the rotary magnetic head device according to the embodiment of the present invention will be described with reference to FIG. In FIG. 3, the drum processing device 60 includes a main shaft 61 that rotates a workpiece 90 indicated by a two-dot chain line, and the workpiece 90 is held by a chuck 62 provided at the tip thereof. The rotational position of the spindle 61 is detected by the spindle rotary encoder 63.

In this drum processing device 60, reference numeral 6
Reference numeral 5 is an X-axis slider that is reciprocally moved in the arrow X direction by the servomotor 66. This X-axis slider 65
A bite 67 for cutting the bearing holder is attached to the, and moves together with the X-axis slider 65.

The X-axis slider 65 is configured to move up and down in the arrow Z direction by the Z-axis slider 68. Z-axis slider 68 is X-axis slider 6
It is attached to the lower side of 5 and can be moved up and down by a servomotor 69.

Further, a guide groove slider 70 is attached to the X-axis slider 65. The guide groove slider 70 is driven by a servo motor 71, and is moved by an arrow Z relative to the X-axis slider 65.
It is designed to move up and down in the direction of the workpiece 9 with the cutting tool 73 for cutting the tape guide groove attached to the upper end thereof.
A tape guide groove to be described later is formed on the peripheral surface of 0.

Using this drum processing device 60, a fixed drum is processed and manufactured as follows. First, the main shaft 61 is driven to rotate the workpiece 90 held by the chuck 62 at a high speed (for example, 3000 rpm to 5600 rp).
m).

Next, the X-axis slider 65 is moved laterally by the servo motor 66 to move the bite 67 to the spindle 61.
It stops at the position of the central axis N. In this state, the Z axis slider 68 is moved upward by the servo motor 69.

At this time, while slightly moving the cutting tool 67 in the horizontal direction at the upper and lower ends of the workpiece 90,
The workpiece 90 is scraped off by moving 7 up along the central axis N. As a result, the workpiece 9
Hole 9 for inserting a rotary shaft (not shown) in the center of 0
2 and a hole 93 for mounting a bearing (not shown)
Is formed.

After this processing step is completed, the X-axis slider 65 is lowered to return the cutting tool 67 to its original position, and the X-axis slider 65 is laterally moved by a predetermined distance and stopped. From this state, the X-axis slider 65 is moved upward, and the tool holder 67 cuts the holes 92 and 93 into a cylindrical shape to form the bearing holder 91.

After that, the outer peripheral surface of the workpiece 90 is cut into a circular shape, and the tape guide groove 97 is formed in the outer peripheral surface to form the fixed drum 95.

Specifically, the main shaft 61 is rotated at a low speed, and X
The shaft slider 65 is moved laterally to stop the cutting tool 73 at the outer peripheral position of the workpiece 90. Then, the X-axis slider 65, the guide groove slider 70, and the Z-axis slider 68 are moved to move the cutting tool 73 up, down, left, and right, so that the tape running surface 96 of the fixed drum 95,
A tape guide groove 97 that is obliquely inclined along the outer peripheral surface is formed by cutting.

At this time, the main shaft rotary encoder 63 reads the rotational position of the main shaft 61, that is, the workpiece 90, and the X-axis slider 65, the guide groove slider 70, and the Z-axis slider 68 are moved in synchronization with this rotational position. Then, the fixed drum 95 is cut and formed so that the center P of the fixed drum 95 is eccentric from the center N of the bearing holder 91 by a predetermined distance (for example, 5 μm to 15 μm from the rotation center L). Through these steps, the eccentric fixed drum 95 integral with the bearing holder 91 is formed.

Therefore, if the fixed drum 95 manufactured in this embodiment is used, when the rotary magnetic head device is assembled, the bearing holder 9 can be automatically installed simply by incorporating the fixed drum 95.
1 is also incorporated. Therefore, the number of steps for assembling the rotary magnetic head device can be reduced, and the cost of the product can be reduced.

[0047]

As described above, according to the rotary magnetic head device of the present invention, the center of the fixed drum is eccentric from the center of rotation of the rotary drum in response to the deviation of the air film distribution, so that the magnetic tape is used. The running center of is almost eccentric from the center of the fixed drum. Therefore, since the magnetic tape runs without being detached from the fixed drum,
At this time, the track linearity of the recorded magnetic tape is improved. Further, the magnetic tape recorded by another device can be reproduced by the rotary magnetic head device of the present invention. Furthermore, since the running magnetic tape has a uniform shape in the width direction, spacing loss does not occur, and the contact characteristics between the magnetic tape and the magnetic head can be improved. Further, according to the drum manufacturing method of the rotary magnetic head device of the present invention,
A fixed drum integrated with the bearing holder is machined, and when assembling the rotary magnetic head device, the bearing holder is automatically installed by simply assembling the fixed drum, so the number of assembly steps can be reduced. The cost can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a rotary magnetic head device according to an embodiment of the invention.

FIG. 2 is a schematic plan view showing an eccentric state of a fixed drum.

FIG. 3 is a schematic front view showing a drum processing device to which the drum manufacturing method of the rotary magnetic head device according to the embodiment of the invention is applied.

FIG. 4 is a schematic front view showing a rotary magnetic head device according to a conventional example.

FIG. 5 is a schematic plan view showing a distribution state of an air film.

[Explanation of symbols]

 1 Rotary Magnetic Head Device 21,91 Bearing Holder 11,95 Fixed Drum 35 Rotary Drum 200 Magnetic Tape A Air Film M Center of Fixed Drum L Center of Rotation of Drum 60 Drum Machining Device 61 Spindle 90 Workpiece 65,68,70 Slider 67,73 bytes 66,69,71 Servo motor

Claims (5)

[Claims] 1. A fixed drum having a bearing holder,
In a rotary magnetic head device including a rotary drum rotatably supported by the bearing holder, the center of the fixed drum is a distribution of an air film generated between a rotating peripheral surface of the rotary drum and a running magnetic tape. A rotary magnetic head device, which is eccentric from the center of rotation of the rotary drum in response to the bias. 2. The center of the fixed drum is eccentric from the center of rotation of the rotating drum so that the center of rotation of the magnetic tape substantially coincides with the center of rotation of the magnetic tape.
The rotary magnetic head device described in 1. 3. The fixed drum is formed separately from the bearing holder, and is assembled to the bearing holder with the center thereof being eccentric from the rotation center of the rotating drum. The rotary magnetic head device according to claim 1 or 2. 4. A drum manufacturing method for a rotary magnetic head device comprising a rotary drum and a fixed drum, wherein a center hole having a predetermined shape is formed at the center of a workpiece, and
The bearing hole for rotatably supporting the rotating shaft of the rotary drum is machined to form a cylindrical shape around the center hole, and the outer peripheral surface of the workpiece on which the bearing holder is machined is formed. A method for manufacturing a drum of a rotary magnetic head device, characterized in that a fixed drum integral with the bearing holder is machined by forming a tape guide groove projecting on the outer peripheral surface of the drum in a circular shape. 5. The method for manufacturing a drum of a rotary magnetic head apparatus according to claim 4, wherein the fixed drum is processed and formed so that the center of the fixed drum is eccentric from the center of the bearing holder by a predetermined distance.