JPS6316020Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention involves winding a magnetic tape in a spiral shape at a predetermined angle around a cylindrical rotating cylinder having two magnetic heads, and running the magnetic tape in a spiral manner at a predetermined angle. This relates to a rotary head device that sequentially records or reproduces signals as a recording trajectory, and is intended to provide stable running of the magnetic tape and stable contact between the magnetic head and the magnetic tape.

A magnetic recording/reproducing device (VTR) has conventionally utilized this type of rotating head device.

FIG. 1 shows an example of a rotary head device for this VTR. A rotary cylinder 2 is provided with two magnetic heads 1 at 180° positions (one magnetic head is shown, the other is omitted), and a spiral guide portion 4 for guiding a magnetic tape 3 is provided on the outer periphery. The outer diameter of the rotary cylinder 2 is slightly larger (about 10 to 20 μm) than the outer diameter of the fixed cylinder 5 to record and reproduce video signals by rotating the fixed cylinder 5. 3 generates a restraining force in the direction of the arrow to effectively make the end surface of the magnetic tape adhere to the fixed cylinder 5. For this reason, the magnetic tape 3 and the rotating cylinder 2 tend to come into contact with each other at the ends of the rotating cylinder (FIGS. 2 and 3) where the magnetic tape is less likely to be floated by the air film, and especially at the window. The phenomenon is remarkable. Furthermore, in recent small-cylinder diameter VTRs with advanced high-density recording, the relative speed between the magnetic tape and the head is slow, so the absolute amount of air film generated is small; 3 tends to decrease from the entrance side to the exit side of the rotating cylinder 2 (rotating in the direction of the arrow), so the end of the magnetic tape 3 and the rotating cylinder 2 come into strong contact, especially at the exit side of the rotating cylinder, and the magnetic tape And the problem of further damage to the surface of the rotating cylinder has arisen. Furthermore, this phenomenon causes even more severe damage to the rotating cylinder in tapes in which the metal is directly deposited on the base surface without using a binder. One way to solve this problem is to make the outer diameter of the rotating cylinder slightly smaller than that of the fixed cylinder so that the magnetic tape does not come into contact with the end of the rotating cylinder over the entire area around which the magnetic tape is wound. There's a problem. As shown in FIG. 5, the rotary cylinder 2 rotates in the direction of the arrow, and the magnetic tape 3 runs in the direction of the head 1.
In a VTR that scans the magnetic tape 3 from below to above, as shown in Fig. 6, on the output side of the rotary cylinder 2 (Fig. 6a), the contact area with the fixed cylinder 5 is large, so the magnetic tape Although the running is stable, the edge of the magnetic tape rides on the fixed cylinder 5 on the entry side of the rotating cylinder 2 (Fig. 6b), where the contact area with the rotating cylinder 2 is small and the magnetic tape levitation is large due to the air film. There is a problem that the running becomes unstable and the compatibility of video track linearity etc. deteriorates. In the present invention, the outer circumferential surface of the fixed cylinder protrudes from the rotary cylinder on the rotary cylinder exit side as shown in FIG. This problem is solved by deviating the fixed center of the rotary cylinder from the axis.

FIG. 7 shows a first embodiment of the present invention, in which a rotating cylinder 2 and a fixed cylinder 4 rotate in the direction of the arrow.
As in the past, the rotary cylinder 2 has a slightly larger outer diameter and is configured to stabilize the running of the magnetic tape, and the center of rotation of the rotary cylinder 2 is relative to the axis of the fixed cylinder 4. , is deflected toward the inlet side of the rotating cylinder. With this configuration, as shown in FIG.
Regarding figure a), the rotating cylinder 2 protrudes from the fixed cylinder 5, and the running of the magnetic tape 3 is stabilized,
On the exit side (Fig. 8b), the fixed cylinder 5 protrudes from the rotating cylinder 2, so the magnetic tape 3
Since the end portion of the rotary cylinder 2 does not come into contact with the rotary cylinder 2, damage to the rotary cylinder and the magnetic tape can be prevented.
The amount of deviation at this time may be set within a range that does not interfere with the contact between the magnetic head and the magnetic tape.

In addition, as an example of FIG. 2, as shown in FIG. 9, the outer diameter of the rotary cylinder 2 is made smaller than that of the fixed cylinder 5, and the center of rotation of the rotary cylinder is moved toward the entrance side of the rotary cylinder with respect to the axis of the fixed cylinder 5. If the structure is such that the difference in level between the outer circumferential surfaces of both cylinders is reduced on the entry side and the fixed cylinder protrudes from the rotary cylinder on the exit side, compared to the first embodiment, Although the effect on stabilizing the running of the magnetic tape at the entrance side is reduced, damage at the entrance side can be reduced. Further, it is effective if the deflection direction of the rotation center of the rotating cylinder is within the range from the entry side to the 90 degree position of the cylinder. This also applies to the first embodiment.

As described above, in the present invention, the fixed cylinder is made to protrude from the rotating cylinder on the output side of the rotating cylinder where the amount of air film generated is small, and conversely, the contact area between the magnetic tape and the fixed cylinder is narrow and the amount of air film generated is reduced. By making the rotary cylinder protrude from the fixed cylinder on the input side of the rotary cylinder, the contact between the end of the rotary cylinder and the magnetic tape on the output side of the rotary cylinder can be prevented without deteriorating the running of the magnetic tape in the cylinder section. This is effective in preventing damage to the magnetic tape and the end of the rotating cylinder. In addition, the outer diameter of the rotary cylinder is made slightly smaller than that of the fixed cylinder, and the center of rotation of the rotary cylinder is offset toward the entrance side of the rotary cylinder with respect to the axis of the fixed cylinder, so that the outer circumferential surface of the rotary cylinder is To prevent the magnetic tape from coming into contact with the end of the rotating cylinder over the entire circumference of the cylinder by configuring the fixed cylinder so that the level difference with the outer circumferential surface of the fixed cylinder is reduced and by configuring the fixed cylinder to protrude from the rotating cylinder at the exit side. This is more effective in preventing damage.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing an example of a conventional rotating head device, Fig. 2 is a partial perspective view showing the end of a rotating cylinder and a magnetic head protrusion window, and Fig. 3 is a conventional rotating cylinder, fixed cylinder, and magnetic tape. FIG. 4 is a plan view showing the distribution of the air film on the rotating cylinder, FIG. 5 is a front view showing the running state of the magnetic tape in the cylinder, and FIG. 6 is the rotating cylinder. FIG. 7 is a plan view showing the first embodiment of the present invention, and FIG. 8 is a cross-sectional view showing the contact state of the magnetic tape when the outer diameter of the rotating cylinder is reduced. FIG. 9 is a cross-sectional view showing the contact state of the magnetic tape on the output side, and a plan view showing the second embodiment of the present invention. 1... Magnetic head, 2... Rotating cylinder, 3...
...Magnetic tape, 4...Guiding step, 5...Fixed cylinder.

Claims (1)

[Claims for Utility Model Registration] (1) A rotary cylinder having two magnetic heads is rotatably provided on a fixed cylinder having a guide step on its outer peripheral surface, and a magnetic tape is attached to the guide step at one end thereof. In a rotating head device in which the magnetic tape is moved around both the stationary cylinder and the rotating cylinder at a predetermined angle with their edges abutting each other, at a position where the opposing area of the magnetic tape and the stationary cylinder is large, the outer periphery of the stationary cylinder is rotated. so that it protrudes from the outer circumference of the cylinder,
The center of rotation of the rotary cylinder is arranged offset with respect to the axis of the fixed cylinder so that the outer circumference of the rotary cylinder protrudes from the outer circumference of the fixed cylinder in a position where the contact area is narrow. Characteristic rotating head device. (2) The outer diameter of the rotary cylinder is made smaller than that of the fixed cylinder, and the center of rotation of the rotary cylinder is deviated from the axis of the fixed cylinder in a direction where the contact area of the magnetic tape with the fixed cylinder is narrowed. A rotary head device according to claim 1 of the utility model registration claim, characterized in that: