JPH045087Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a rotary head device installed in a magnetic recording/reproducing device such as a VTR or a PCM recorder/player.

[Prior art and its problems]

FIG. 6 is a front view of a conventional rotary head device.

This rotating head device has a fixed cylinder 2 fixed on a chassis 1 and a rotating cylinder 3 rotationally driven by a motor. FIG. 7 shows the rotary cylinder 3 from the lower surface (the surface facing the fixed cylinder 2). Four base plates 4 are fixed to the lower surface 3b of the rotary cylinder 3, and a magnetic head H is fixed onto the base plates 4. This base plate 4 extends inward from the outer periphery of the rotary cylinder 3 along the radius of the cylinder 3. Further, a guide portion 2a is formed on the outer peripheral surface of the fixed cylinder 2, and the magnetic tape T can be guided by this guide portion 2a. In Figure 6, tape T
This conceptually shows the direction of travel. The tape T is spirally wound around the fixed cylinder 2 and the rotating cylinder 3 and is fed in the direction of the arrow. When the rotating cylinder 3 is driven by a motor, the magnetic head H
However, the spirally wound tape T is scanned at high speed. This is the so-called helical scan.

In this type of rotary head device, the fixed cylinder 2
The rotating cylinder 3 further slides at high speed with respect to the magnetic tape T which slides in the direction of the arrow. Since the outer circumferential surface of the rotating cylinder 3 is finished smoothly, the magnetic tape T sliding at high speed is easily attracted to the outer circumferential surface of the rotating cylinder 3. When the running magnetic tape T comes into close contact with the outer periphery of the rotating cylinder 3, the tape becomes unable to run.

To prevent this kind of phenomenon from occurring,
In the conventional rotary head device, a plurality of air grooves 3a are formed in the outer peripheral surface of the rotary cylinder 3 in parallel and along the outer peripheral surface of the cylinder. When the rotating cylinder 3 rotates, the air groove 3a on the outer circumferential surface and the magnetic tape T
An air film is formed between the magnetic tape T and the recording surface of the rotary cylinder 3, and the magnetic tape T rises from the outer peripheral surface of the rotary cylinder 3, thereby reducing sliding resistance.

However, in the case of recent 8mm videos, etc., it is necessary to increase the recording density of information, so a smooth magnetic tape with a surface close to a metal surface is used. Therefore, the adhesion of the magnetic tape T to the cylinder becomes even more remarkable. Therefore, in order to construct a rotary head device that uses an 8 mm video tape, it is conceivable to devise the spacing and shape of the air grooves 3a on the outer peripheral surface of the rotary cylinder 3. However, with such countermeasures, it is often still difficult to sufficiently lift the magnetic tape from the rotating cylinder 3. Furthermore, as shown in FIG. 5, even if an air film can be formed between the air groove 3a and the magnetic tape T to lift the magnetic tape T from the outer peripheral surface of the rotating cylinder 3, the fixed cylinder The magnetic tape T remains in close contact with the outer circumferential surface of the fixed cylinder 2 at the portion where it is in contact with the outer circumferential surface of the fixed cylinder 2. Since the relative speed due to sliding between the outer circumferential surface of the fixed cylinder 2 and the magnetic tape T is small, the influence of close contact between the tapes is smaller than in the case of the rotating cylinder 3, but it is still a problem in terms of tape running accuracy, etc. .

FIG. 8 shows a conventional example for dealing with the above problems. FIG. 8 corresponds to the - sectional view of FIG. 6. In this conventional example, the rotary cylinder 3
A plurality of spiral grooves 3b are formed on the surface 3b facing the fixed cylinder 2, the spiral grooves 3b extending diagonally while widening in the direction opposite to the rotational direction. If this rotating cylinder 3 is used, when it rotates on the fixed cylinder 2, the spiral groove 3
Air flows out along c, thereby
The portion of the magnetic tape T located between the fixed cylinder 2 and the rotating cylinder 3 comes to float. By using the rotary cylinder 3 having such a structure, it becomes possible to realize good tape running even for 8 mm video tape. A rotary head device using this type of rotary cylinder is disclosed in, for example, Japanese Patent Laid-Open No. 59-38961.

When manufacturing a rotating cylinder as shown in Fig. 8, it is necessary to machine a spiral groove 3c, but it is extremely difficult to accurately machine such a spiral groove 3c. This method has the disadvantage that it increases the cost and is difficult to implement in a small and inexpensive magnetic recording/reproducing device.

[Purpose of the invention] The present invention was made by focusing on the above-mentioned problems of the conventional technology.
Moreover, it is an object of the present invention to provide a rotary head device that can be manufactured at low cost.

[Summary of the idea]

The present invention is a rotary head in which a rotary cylinder that is rotationally driven by a motor is provided on a fixed cylinder, and a base plate that supports a magnetic head is fixed to the surface of the rotary cylinder that faces the fixed cylinder. In the device, the side edge of the base plate in the rotational direction extends from the outer periphery of the rotating cylinder toward the inside of the cylinder;
It is characterized by extending obliquely toward the direction of rotation. Since the side edge of the base plate to which the magnetic head is fixed is formed in a state similar to a spiral groove, as the rotary cylinder rotates, air flows out from the side edge toward the outer circumference of the cylinder, and the tape is The center part will lift up from the cylinder, allowing the tape to run smoothly. In addition, the side edge of the base plate that fixes the magnetic head is shaped to extend diagonally inward to the rotating cylinder.
Compared to the spiral groove shown in FIG. 8, it is easier to process and can be manufactured at lower cost.

[Example of idea]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 is a front view showing a rotary cylinder used in a rotary head device according to an embodiment of the present invention, and FIG. 2 is a plan view showing the rotary cylinder from the side facing the fixed cylinder.

The rotating cylinder 3 shown in FIG. 1 is rotatably driven by a motor on a fixed cylinder 2 fixed on the chassis 1, similar to the conventional rotating head device shown in FIG. As shown in FIG. 2, a plurality of (four in the illustrated embodiment) base plates 4 are fixedly installed on the surface 3b of the rotary cylinder 3 facing the fixed cylinder, and the magnetic head H is connected to each of the base plates 4. It is fixedly installed on the base plate 4. The shape of each base plate 4 is such that the edge 4a on the rotation direction side faces the inside of the rotation cylinder 3.
It extends at a predetermined angle in the rotational direction with respect to the cylinder radius.

Further, a guide portion 2 is provided on the outer peripheral surface of the fixed cylinder 2.
a is formed, and the magnetic tape T can be guided by this guide portion 2a.

Furthermore, air grooves 3a are formed on the surface of the rotating cylinder 3. A plurality of air grooves 3a are formed in parallel along the circumferential direction of the rotary cylinder 3.

Next, the operation of the present invention will be explained.

As shown in FIG. 6, the tape T is spirally wound around the fixed cylinder 2 and the rotating cylinder 3, and is fed in the direction of the arrow in the figure. When the rotating cylinder 3 is driven by a motor,
The magnetic head H scans the spirally wound tape with respect to T at high speed.

During operation, an air film is formed on the contact surface between the tape T and the rotating cylinder 3 due to the flow of air in the air groove 3a of the rotating cylinder 3, and the tape T is slightly lifted from the surface of the rotating cylinder 3.
Furthermore, since the side edge 4a of the base plate 4 to which the magnetic head H is fixed is formed obliquely along the rotational direction of the rotary cylinder 3, the air inside the cylinder flows to the side edge according to the rotational movement. 4a to the outer circumferential direction. Therefore, as shown in FIG. 4, the central portion of the magnetic tape T is lifted from the outer peripheral surface of the cylinder due to the flow of air along the side edge 4a. Therefore, the magnetic tape T can smoothly slide along the outer peripheral surfaces of the fixed cylinder 2 and the rotating cylinder 3.

Next, FIGS. 3A, B, C, and D show the shape of the base plate 4 in an enlarged manner by type. What is shown in Figure A is the same as that implemented in Figure 2. The one shown in Figure B has a side edge 4a that is slightly swollen. In the base plate 4 shown in Figures C and D, the shape of the side edge 4a is the same as in Figures A and B, respectively, but the rear edge 4b facing inward of the cylinder extends diagonally. ing. This allows the length of the side edge portion 4a to be increased.

[Effect of idea]

As described above, according to the present invention, the following effects can be achieved.

(1) The side edge of the base plate for fixing the magnetic head formed on the rotating cylinder is formed so as to extend diagonally inward from the circumferential surface of the cylinder in the direction of cylinder rotation, so that the rotating cylinder can be rotated. At this time, air flows out of the cylinder along this side edge, and this air causes the central portion of the magnetic tape to rise above the outer peripheral surface of the cylinder. This allows the magnetic tape to slide smoothly against the outer peripheral surface of the cylinder without coming into close contact with it. By using the shape of the base plate for fixing the magnetic head and the air grooves on the outer circumferential surface of the rotating cylinder, good tape running is achieved even on smooth surfaces such as 8mm video tapes. become able to.

(2) The side edges of the base plate that fixes the magnetic head are formed obliquely, and these side edges promote the outflow of air. Therefore, there is no need to newly form a spiral groove as shown in FIG. Therefore, it can be manufactured at low cost. In particular, there is a limit to how thin the base plate can be made due to warping, etc., and even if the entire rotating head device is downsized, the base plate still needs to be thick to a certain extent. Therefore, it is an effective means to form an air flow using the side edges of the base plate.

[Brief explanation of the drawing]

Fig. 1 is a front view showing a rotating cylinder used in a rotating head device according to an embodiment of the present invention, Fig. 2 is an enlarged plan view showing the surface of the rotating cylinder facing the fixed cylinder, and Fig. 3. A to D are plan views showing the shapes of the base plates according to the embodiments, FIG. 4 is a partially enlarged sectional view of a rotary head device according to an embodiment of the present invention, and FIG. 5 is a partially enlarged sectional view of a conventional rotary head device. FIG. 6 is a front view showing an outline of the rotary head device and the running state of the magnetic tape, FIG. 7 is a plan view showing the surface of the rotary cylinder facing the fixed cylinder used in the conventional rotary head device, and FIG. The figure is a cross-sectional view taken from FIG. 6 showing a conventional rotating cylinder. 2...Fixed cylinder, 3...Rotating cylinder, 3
a... Air groove, 3b... Surface of the rotating head facing the fixed head, 4... Base plate, 4a... Side edge of base plate, H... Magnetic head, T... Magnetic tape.

Claims (1)

[Scope of utility model registration request] In the rotary head device, a rotary cylinder rotatably driven by a motor is provided on the fixed cylinder, and a base plate for supporting a magnetic head is fixed to a surface of the rotary cylinder facing the fixed cylinder. A rotary head device characterized in that a side edge of the base plate in the rotation direction extends diagonally from the outer circumference of the rotary cylinder toward the inside of the cylinder.