JPH0535447Y2 - - Google Patents

Description

[Detailed explanation of the invention] (a) Industrial application field This invention is applicable to video tape recorders (VTR) and digital audio tape recorders (DAT).
This invention relates to a rotating cylinder device.

(b) Prior art In a direct drive type rotary cylinder device used in a VTR, etc., the cylinder motor that drives the rotary cylinder is placed outside the cylinder near the bottom surface of the fixed cylinder, and the rotary cylinder and cylinder motor are connected to the fixed cylinder. A common structure is that they are connected by a rotating support shaft that passes through them. However, in the rotating cylinder device having the above-described structure, the thickness of the cylinder portion and the cylinder motor portion imposes large restrictions on miniaturization of the VTR.
For this reason, a rotating cylinder device having a structure in which a cylinder motor section is disposed inside the cylinder has been considered.

A rotating cylinder device with a structure in which the rotor magnet of the cylinder motor is placed on the upper surface of the rotating cylinder, and the stator coil of the cylinder motor is fixed above the rotor magnet so as to be integrated with the fixed cylinder at the bottom, was developed in 1983. -Described in Publication No. 101320 (G11B5/52). Furthermore, regarding a rotating cylinder device having a structure in which the rotor magnet of the cylinder motor is arranged on the lower surface of the rotating cylinder and the stator coil part of the cylinder motor is arranged inside the fixed cylinder, Japanese Patent Application Laid-Open No. 16204/1988 (G11B5/02) It is described in.

(c) Problems that the device aims to solve However, in a rotating cylinder device having a structure in which the cylinder motor unit is located inside the cylinder as described above, the magnetic head and rotor magnet are arranged on the rotating cylinder, so that the magnetic head and rotor magnet are close to each other, and the effect that leakage magnetic flux from the rotor magnet has on the recording and playback characteristics of the magnetic head becomes a problem.

The object of the present invention is to prevent the recording and reproducing characteristics of the magnetic head from deteriorating due to the leakage magnetic flux of the rotor magnet when the magnetic head and the rotor magnet are placed close to each other.

(d) Means for solving the problems The present invention provides a rotary cylinder that is equipped with a magnetic head on the outer periphery and that is supported on a fixed cylinder and rotates.
In a rotary cylinder device in which a multi-pole magnetized rotor magnet of a cylinder motor for driving the rotary cylinder is arranged so as to rotate together, the center of the magnetic pole of the rotor magnet and the head gear of the magnetic head are connected. , are arranged on the same plane that includes the rotation center of the rotary cylinder.

(e) Effect Therefore, in the present invention, a rotor magnet and a magnetic head provided in a rotating cylinder are arranged so that the center of the magnetic pole of the rotor magnet and the head gap of the magnetic head are on the same plane that includes the center of rotation of the rotating cylinder. By arranging it so that it is located at the top,
In the vicinity of the head gap, the leakage magnetic flux generated by the rotor magnet and the magnetic flux generated due to recording/reproduction of the magnetic head are generated so as to be substantially perpendicular to each other, so that the leakage magnetic flux causes the recording by the magnetic head. This prevents the playback characteristics from deteriorating.

(f) Example An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of a rotary cylinder device according to the present invention. In the figure, 1 is a fixed shaft, and the fixed shaft 1 is supported by a fixed cylinder 2. The rotating cylinder 3 is attached to a flywheel disk 12, and the flywheel disk 12 is attached to the fixed shaft 1 via a bearing portion 11 so as to rotate around the fixed shaft 1.
A head base 4 with a magnetic head 5 attached thereto is screwed to the outer periphery of the lower surface of the rotating cylinder 3, and a multi-pole magnetized rotor magnet 6 of a cylinder motor that drives the rotating cylinder 3 is attached to the upper surface. is attached via a rotor yoke 7. Reference numeral 9 denotes a rotor-side rotary transformer attached to the flywheel disk 12, and transmits recording and reproducing signals between it and the stator-side rotary transformer 10 attached to the fixed cylinder 2. 8 is a stator coil of a cylinder motor supported by a fixed shaft.

In the rotating cylinder device shown in FIG. 1, when a current flows through the stator coil 8, a driving force is generated between the stator coil 8 and the rotor magnet 6, and the rotating cylinder 3 rotates around the fixed shaft 1 together with the magnetic head 5.

FIG. 2 is a plan view of the rotary cylinder device shown in FIG. 1 with the stator coil 8 section removed;
In the figure, the same parts as in FIG. 1 are given the same numbers. In the present invention, as shown in the figure, the center 23 of the magnetic pole of the rotor magnet 6 and the head gap 22 of the magnetic head 5 are aligned with the center of rotation 2 of the rotary cylinder 3.
1 and are arranged on the same plane.

In a rotary cylinder device as in this embodiment, in which the rotor magnet 6 of the cylinder motor is disposed on the rotary cylinder 3 to which the magnetic head 5 is attached, the magnetic head 5 and the rotor magnet 6 are arranged in close proximity. There is. In this case, even if the leakage magnetic flux near the rotor magnet 6 is small, the magnetic flux concentrates near the magnetic head 5 due to the magnetic permeability of the magnetic head 5. Therefore, the leakage magnetic flux is Characteristics may be affected.

In the conventional rotating cylinder device, even when the magnetic head 5 and the rotor magnet 6 are close to each other, the positional relationship between the poles of the rotor magnet 6 and the head gap 22 is not particularly considered.
The rotor magnet 6 and the magnetic head 5 may be arranged in the positional relationship shown in FIGS. 3 and 4. In FIG. 4, the magnetic pole boundary 24 of the rotor magnet 6 and the head gap 22 of the magnetic head 5 are arranged on the same plane containing the rotation center 21 of the rotating cylinder 3. In FIG.

5 and 6 show the area near the magnetic head 5.
This is a diagram showing the leakage magnetic flux of the rotor magnet 6, and schematically shows the case viewed from the front end side of the magnetic head 5 in the horizontal direction. The positional relationship between the magnetic head 5 and the poles of the rotor magnet 6 corresponds between FIG. 2 and FIG. 5, and FIG. 4 and FIG. 6, respectively. In the case of the positional relationship shown in FIG. 4, as shown in FIG. 6, in the head gap 22 part, the leakage magnetic flux A' of the rotor magnet 6 and the magnetic flux B' generated due to recording and reproduction of the magnetic head are generated. are almost parallel. In such a case, the output level of the reproduction signal reproduced by the magnetic head 5 is suppressed.

In contrast, in the present invention, the positional relationship between the poles of the rotor magnet 6 and the head gap 22 is as shown in FIG. As shown in FIG. 5, the leakage magnetic flux A in this case is almost perpendicular to the magnetic flux B generated due to the recording and reproduction of the magnetic head 5 at the head gap 22 portion. In such a case, the influence of leakage magnetic flux on the output level of the reproduced signal is very small.

(g) Effect of the invention As described above, according to the invention, when the magnetic head and the rotor magnet are placed close to each other, the leakage magnetic flux of the rotor magnet reduces the recording by the magnetic head. This prevents the reproduction characteristics from deteriorating, which is highly effective.

[Brief explanation of the drawing]

Figure 1 is a sectional view of one embodiment of the present invention, Figure 2 is a plan view of Figure 1 with the stator coil removed, and Figures 3 and 4 are of a conventional rotor magnet and magnetic head. Figure 5 showing the positional relationship with
6 are diagrams showing leakage magnetic flux. 2... Fixed cylinder, 3... Rotating cylinder, 5
... Magnetic head, 6 ... Rotor magnet, 21
...Center of rotation, 22...Head gap, 23...
...center of magnetic pole.

Claims (1)

[Claims for Utility Model Registration] A rotating cylinder that rotates around a fixed shaft with an opposing gap formed between it and a fixed cylinder, a pair of magnetic heads disposed opposite to each other on the lower surface of the rotating cylinder, and a pair of magnetic heads disposed inside the rotating cylinder. In a rotary cylinder device having a rotor magnet housed in the rotor magnet, the head gap of the magnetic head is arranged on a plane parallel to the fixed axis and including the center of the magnetic pole of the rotor magnet and the center of rotation of the rotary cylinder. A rotating cylinder device characterized by: