JPS5947365B2 - Tape guide drum no. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a tape guide drum, and particularly provides a method that can minimize changes in height relative to an ideal rotating surface, that is, surface runout, during rotation of a rotating magnetic head. This is what I am trying to do.

In a rotating magnetic head type magnetic recording and reproducing device, one or more rotating magnetic heads are rotated to record and reproduce signals on a magnetic tape. When this occurs, the recording locus on the magnetic tape and the reproduction locus do not match correctly, resulting in a local drop in the reproduction signal level, resulting in a noisy reproduction screen.

Therefore, surface wobbling during rotation of the rotating magnetic head becomes a very serious problem when compatibility between magnetic tapes is required. The main factors that cause surface runout during rotation of a rotating magnetic head are that the rotating body itself that attaches the rotating magnetic head to the rotating main shaft is mounted in a way that causes surface runout, and that the main shaft is There are two possible causes: insufficient preload on the rotatably supported bearing, too large a fitting clearance, and grinding motion caused by uneven ball diameters.

. Many attempts have been made to eliminate these factors.

One method is to press-fit the rotating body that holds the rotating magnetic head into the main shaft or fix it with screws, etc., and then cut the rotating magnetic head mounting surface based on the outer periphery of the main shaft. There is a way to correct the misalignment. However, the tape guide drum manufactured by this method cannot eliminate surface runout caused by the bearing portion. In order to solve this problem, the following methods have been proposed.

To explain this with reference to FIG. 1, the rotating body 1 to which the rotating magnetic head is attached is integrated with the main shaft 2, and the bearing part 4 of the tape guide drum 3 is rotatably supported as a bearing. A pulley 5 is attached to one end of the main shaft 2, and the rotating body 1 is rotated by a belt 7 driven by an external motor 6, and the mounting surface of the rotating magnetic head of the rotating body 1 is cut using a cutting tool 8 to correct surface runout. This is the way to do it.
According to this method, since the rotating body is supported by the bearing part of the tape guide drum itself, the above-mentioned drawbacks can be almost eliminated. However, according to this method, it is necessary to apply an appropriate amount of tension to the belt between the external motor 6 and the pulley 5, and this belt tension always applies force to the bearing in one direction. Very little (
This causes a change in movement, albeit on the order of .mu.m), and the main shaft rotates at a position different from the rotational position of the main shaft when the belt 7 is not applied. Therefore, although the surface runout of the rotating body can be reduced when the belt 7 is applied, when the belt 7 is removed, the surface runout increases on the order of μm. Generally, surface runout during rotation of a rotating magnetic head is often inspected by the tape guide drum alone, and at that time the belt 7 is removed, making it difficult to improve yield due to this problem.

The present invention can eliminate these drawbacks. This will be explained in detail based on examples. FIG. 2 is an assembled view of an embodiment of a tape guide drum according to the method of the present invention. The cylinder part that winds and guides the magnetic tape 11 around its outer periphery consists of an upper cylinder 12 and a lower cylinder 13, and a cylinder receiver 14 connects the upper cylinder 12
and a lower cylinder 13, which are held by a cylinder receiver 14 so that a predetermined gap 15 is maintained between the upper cylinder 12 and the lower cylinder 13.

The rotating magnetic head 16 is connected to the rotating magnetic head of the first rotating body 17 .
It is fixed to the head mounting fixing surface 18. The second rotating body 19 has a reference surface 36 on which the rotating magnetic head fixing surface 18 of the first rotating body 17 is aligned and placed.
0 and rotates together with it. This tape guide drum has a built-in brushless motor 21 for driving the rotating magnetic head 16, and a rotor 22 made of a permanent magnet is integrated with the main shaft 20 via a rotor fixing boss 23. Therefore, the rotating magnetic head 18 is directly rotationally driven by the brushless motor 21. The stator 24 is wrapped in cotton so as to correspond to the rotor 22.
It is fixed to a bearing portion 25 that rotatably supports the rotor 22, main shaft 20, etc. The windings wound around the stator 24 of the brushless motor 21 are wound into multiple phases.
Current switching to each winding is achieved by forming protrusions at multiple points in the inner circumferential direction of the stator 24, and applying a high-frequency signal to the single point.
A position detection stator 26 having a secondary coil and a secondary coil for obtaining an induction signal is attached to the rotor fixing boss 23 so as to correspond to the position detection stator 26, and rotates together with the rotor 22.

With the position detection rotor 27 having a plurality of protrusions formed on its outer periphery, the current is sequentially switched by the induction signal level of the secondary coil of the position detection stator 26, which changes in response to the protrusions of the position detection rotor 27. It is something. Current is supplied to the windings by a drive circuit 29 via a printed circuit board 28 attached to the stator 24.

The bearing portion 25 has an upper housing 30 and a lower housing 31.
The ball bearings are divided into 32 and 3 ball bearings respectively.
Holds 3.

Further, the cylinder portion and the bearing portion 25 are integrated by screwing the lower cylinder 13 and the upper housing 30 together.

Transmission of signals from the rotating magnetic head 16 between the stationary part and the rotating part is achieved by using a rotor 34 of a rotary transformer that rotates together with the second rotating body 19 and a rotary transformer installed in the upper housing 30 so as to correspond to the rotary transformer rotor 34. This is done between the rotary transformer stator 35 and the rotary transformer stator 35.

In the tape guide drum having the above configuration, the reference surface 36 of the second rotating body 19, which requires surface runout precision, is corrected by the following method to ensure precision.

One embodiment will be described with reference to FIG. A drive circuit 29 is connected to the tape guide drum to make it rotatable, and the bottom surface 40 of the lower cylinder 13 is supported and fixed on a support stand 37. However, at this time, the tape guide drum is in the same state as shown in FIG. 2 with the first rotating body 17 removed, and the reference surface 36 of the second rotating body 19 is cut with a cutting tool 38 to correct surface runout. It is located so that cutting is possible. The reference surface 36 of the second rotating body 19 includes a cutting allowance for correcting surface wobbling in advance when assembling the tape guide drum. After completing the above preparations, drive circuit 2
9 is energized to rotate the brushless motor 21 built into the tape guide drum.

Then, the cutting tool 38 is moved in the direction of arrow A to cut the reference surface 36 of the second rotating body 19 to correct the surface runout. As described above, according to the method of the present invention, the rotating body is supported by the bearing part of the tape guide drum itself, and the reference surface of the rotating body is cut while the tape guide drum itself is generating rotational torque. In fact, there is no change in the rotational position of the bearing, which was considered a drawback in the past.
According to experiments, it was possible to correct the surface runout of the reference surface to 2 μm or less by simply repeating the cutting feed of the cutting tool two to three times.

Furthermore, according to the present invention, the verticality of the main axis with respect to the bottom surface of the lower cylinder is required to be strictly accurate in the tape guide drum, but there is no possibility that the perpendicularity would be impaired due to belt tension caused by conventional belting. . After correcting the surface runout of the reference surface of the second rotating body, the first rotating body to which the rotating magnetic head is attached and the upper cylinder are attached to complete the finished product.
The rotating magnetic head mounting and fixing surface of the first rotating body has been machined in advance so that it has a flatness on the order of μm, and even after it is mounted on the reference surface of the second rotating body, the The surface runout near the outer periphery of the rotary body 1 does not increase significantly, and the amount of surface runout of the rotating magnetic head is within a predetermined standardized amount. Furthermore, in the present invention,
Since a part of the first rotary body on the same side as the surface on which the magnetic head mounting/fixing surface is formed is placed and fixed on the reference surface of the second rotary body after cutting, Even if the first rotating body has partially different thicknesses, simply finishing the magnetic head mounting fixing surface and the mounting surface of the second rotating body with respect to the reference surface with high accuracy will ensure that the magnetic head It also has the effect that it can be rotated well without causing surface runout. As described above, the method of the present invention can easily reduce the surface runout of the rotating magnetic head, and is also effective in reducing the number of steps for assembling and adjusting the tape guide drum.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining a conventional method for correcting surface runout of a reference surface of a rotating body, FIG. 2 is an assembly diagram of a typical example of a tape guide drum according to the method of the present invention, and FIG. FIG. 2 is a diagram for explaining an example of a method. 12... Upper cylinder, 13... Lower cylinder, 16... Magnetic head, 17...
...First rotating body, 19...Second rotating body, 2
0... Main shaft, 21... Brushless motor, 22... Rotor, 24... Stator, 29... Drive circuit, 36... ...Second
Rotating body reference plane, 37... Support stand, 38...
···Cutting tools.

Claims (1)

[Claims] 1. A rotatable first rotating body having a magnetic head attached to a magnetic head fixing surface formed on one surface, and a rotatable first rotating body having a magnetic head attached to the magnetic head fixing surface formed on one surface, and a second rotating body having a reference surface on which a part can be placed and fixed; and a first rotating body disposed at a predetermined interval in the axial direction.
and a rotating shaft rotatably supported by a second ball bearing and having one end directly coupled to the second rotating body, a permanent magnet rotor coupled to the rotating shaft, and a permanent magnet rotor coupled to the rotating shaft, and a permanent magnet rotor coupled to the rotating shaft. When manufacturing a tape guide drum having a motor including a stator that applies rotational torque to a magnetic rotor, the second rotating body is rotated by supplying power to the motor while the motor is fixed and supported on a support. Then, in the rotating state, a cutting tool is brought into contact with the reference surface of the second rotating body, and after cutting the reference surface so that the surface runout is minimized, the cutting tool is placed on the reference surface of the first rotating body. A method for manufacturing a tape guide drum, characterized in that a part of the same surface as the surface on which the magnetic head mounting/fixing surface is formed is placed and fixed.