JPS63311617A - Rotary head assembly for magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To record and reproduce stable information by increasing the outer diameter of a rotary cylinder larger than the other part in the vicinity of a magnetic head. CONSTITUTION:An outer diameter R1 near the magnetic head 6 in a rotary cylinder 5A is larger than the outer diameter R2 of the other part. In selecting the diameters as R1>R2, the downward force F1 acting the tape recording medium 1 is increased locally in the vicinity of the magnetic head 6. Thus, the upward force is exerted to the recording tape medium 1 by a friction caused between the magnetic head 6 and the recording tape medium 1 in the vicinity of the magnetic head 6 and the upward force is compensated by the downward force F1 increased locally in the vicinity of the magnetic head 6. Thus, the vertical movement of the recording tape medium in the vicinity of the magnetic head 6 is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotary head assembly of a magnetic recording/reproducing device such as a video tape recorder or a digital audio tape recorder, and particularly to stabilization of running of a magnetic tape.

[Conventional technology]

FIG. 4 is a longitudinal cross-sectional view of a conventional rotary head assembly of a video tape recorder, FIG. 5 is a front view of a conventional rotary head assembly and a magnetic tape, and FIG. 6 is a view of a conventional rotary cylinder molded with a molding material. FIG.

In the figure, (1) is a tape-shaped recording medium, (2) is a fixed cylinder having a lead groove (201) on the outer circumferential surface that guides the tape-shaped recording medium (υ), and (3) is a fixed cylinder (fixed to 2). Central shaft, (4) is bearing, (5) is bearing (4)
A rotating cylinder rotatably supported from a fixed cylinder (2) via a rotating cylinder (F5 is attached to a rotating cylinder (■) to record information on the tape-shaped recording medium (1) or to record information already on the tape-shaped recording medium (1) (7) is a rotor IJ lance that transmits and receives information without contact between the magnetic head (6) and a fixed side signal processing circuit (not shown); (8) is an electric motor that rotates the rotating cylinder (Q).The rotating cylinder (S) is generally formed by cutting a metal material because it is easy to obtain a certain dimensional accuracy. Since this requires a lot of time and labor, in recent years molded materials such as plastic have been made to reduce costs.

Next, the operation will be explained. When the rotating cylinder (0) is rotated by the electric motor (marked), the magnetic head (6) also rotates around the central axis (3), and is guided along the lead groove (201) to connect the fixed cylinder (2 and the rotating cylinder (5).
) Information is recorded and reproduced on a tape-shaped recording medium (1) that runs on the outer peripheral surface of the recording medium (1). During this time, information to be recorded or reproduced is exchanged between the magnetic head (6) and the signal processing circuit via the rotary transformer (7).

By the way, as shown in FIG. 5, the tape-shaped recording medium (1) running on the outer peripheral surface of the fixed cylinder (2) and the rotating cylinder (0) is subjected to a downward force () that pushes it toward the lead groove (201). Fl) and an upward force (Fl) that tries to lift it from the lead groove (201) act.
The downward force (Fl) is a force generated by the diameter difference between the outer diameter (D) of the fixed cylinder (R) and the outer diameter (D) of the rotating cylinder (■), and in a normal rotating head assembly, this force (PL) is The upward force (P) is the upward force due to the friction generated between the magnetic head (6) and the tape-shaped recording medium (1), and the upward force generated by the fixed cylinder (2). This consists of an upward force generated by the difference in frictional force between the rotating cylinder (S) and the tape-shaped recording medium (1), and this difference in frictional force causes the fixed cylinder (S) and the tape-shaped recording medium (4) to slide against each other. In contrast,
This occurs because an air film (9) is formed between the rotating cylinder (5) and the tape-shaped recording medium (1).

Here, in order to stabilize the running of the tape-shaped recording medium (1) and perform good recording and playback, it is necessary to suppress the vertical movement of the tape-shaped recording medium (1) as P2 and always keep the lead groove (201)
It is necessary to run the vehicle along the following lines.

[Problem that the invention seeks to solve]

The rotary head assembly of a conventional magnetic recording/reproducing device is constructed as described above, and the rotary cylinder (5) is formed by cutting a metal material or molding it with a molding material. is also a downward force (F+) as mentioned above.
>The only way to create an upward force (I'S) is to make the outer diameter (D) of the rotating cylinder (5) > the outer diameter (d) of the fixed cylinder (2).
> d to generate a downward force, (
If D) is too large, the diameter difference between the fixed cylinder (2) and the rotating cylinder (5) will become large, and the rotating cylinder (5) will become larger.
The lower edge of 5) directly contacts the tape-shaped recording medium (1) and damages it. Therefore, the diameter (D) of the rotating cylinder (ω) cannot be made too large. In particular,
When the rotary cylinder (5) is molded with molding material, as shown in FIG. 6, a portion (503) farther from the outside diameter than a portion (502) close to the gate portion (501) facing the entire molding material injection gate. The outer diameter of the tape-shaped recording medium (1) becomes smaller (the reason will be explained later), and when the magnetic head (6) is attached to the small outer diameter part (503), the tape-shaped recording medium (1) Acting downward force (F・1)
Not only is this small, but the amount of protrusion of the magnetic head (6) from the circumferential surface of the rotating cylinder (5) must be increased, which reduces the friction between the magnetic head (6) and the tape-shaped recording medium (1). As a result, the tape-shaped recording medium (1) moves vertically and becomes unstable.On the other hand, the protrusion from the outer peripheral surface of the rotating cylinder (0) of the magnetic head (6) If the overall diameter is increased in order to reduce Σ, the tape-shaped recording medium (1) will be damaged as described above.

As mentioned above, in the conventional rotating head assembly,
In order to increase the force (I's) acting on the tape-shaped recording medium (1), the outer diameter of the rotating cylinder (5) must be increased, which causes damage to the tape-shaped recording medium (υ), If an attempt is made to prevent damage, the above-mentioned downward force (y-force) is not sufficient, causing vertical movement of the tape-shaped recording medium (1), resulting in the problem that stable recording and reproduction of information cannot be performed.

This invention was made in order to solve the problem of the counting point of the conventional device, and it is designed to stabilize the vertical movement of the tape-shaped recording medium without damaging the tape-shaped recording medium, and to stably record and reproduce information. It is an object of the present invention to provide a rotary head assembly for a magnetic recording/reproducing device.

[Means for solving problems]

In the rotary head assembly of the magnetic recording/reproducing apparatus according to the present invention, the outer diameter of the rotary cylinder is larger in the vicinity of the magnetic head than in other parts.

[Effect]

In this invention, by making the outer diameter of the rotating cylinder larger in the vicinity of the magnetic head than in other parts, the downward force in the vicinity of the magnetic head is locally increased.
The upward force due to friction generated between the magnetic head and the tape-shaped recording medium is compensated for, thereby suppressing vertical movement of the tape-shaped recording medium in the vicinity of the magnetic head.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. FIG. 1 is a longitudinal sectional view of a rotating head assembly according to an embodiment of the present invention, and FIG. 2 is a plan view of a rotating cylinder in the embodiment of FIG. The explanation will be omitted.

In the figure, (5A) is a rotary cylinder corresponding to (9) of the conventional type, and has an outer diameter (B) near the magnetic head (6).
1) is larger than the outer diameter (R1) of other parts. By setting R1>R1 in this way, the downward force (F) acting on the tape-shaped recording medium (1) is reduced by the magnetic head (6).
) becomes locally large in the vicinity. Therefore, near the magnetic head (6), the magnetic head (0) and the tape-shaped recording medium (
An upward force acts on the tape-shaped recording medium (1) due to the friction generated between the magnetic head (1) and the downward force (1') that locally increases near 0. +), and the vertical movement of the tape-shaped recording medium near 0 is suppressed.Moreover, the outer diameter of the rotating cylinder (5A) is not increased over the entire circumference, but rather the outer diameter of the magnetic head (6) is Since it is only in the vicinity, the tape-shaped recording medium (1) will not be damaged by the edge of the lower end of the rotary cylinder (5A).

Although such a rotating cylinder can be formed by cutting a metal material, it is preferable to form it by molding a molding material. In other words, molded products are generally made by injecting molten molding material into a mold whose temperature is controlled below the solidification temperature of the molding material. In the farthest part, the amount of heat released into the mold during flow is large, the temperature decreases greatly, and the inside solidifies quickly. Similarly, in the part far from the gate where it meets the molding material injected from another gate (generally called the weld), the ends of the flow of molding material whose temperature has dropped come into contact, so the two flows do not mix sufficiently. Assimilates to the inside quickly. Therefore, in these parts, the amount of molding material packed to cover shrinkage due to cooling is small, and the density is low, resulting in a large amount of shrinkage silver. On the other hand, in the area near the gate, the temperature drop is small and it is slow to solidify to the inside, so until the gate is cooled and solidified and closed, the molding material is replenished to compensate for the shrinkage due to cooling, so the density increases. is high and the amount of shrinkage is low.

The same thing can be said when forming the rotary cylinder (5A) by molding, and the part (5A) near the gate part (501)
02) has less shrinkage, and the outer diameter of the portion (503) far from the gate portion (501) has more shrinkage.

Therefore, when forming the rotating cylinder (5A) by molding, as shown in FIG.
) and a large diameter part (502), so you can use this large diameter part (502) to attach the magnetic head (■).As mentioned earlier, the rotating cylinder (5mm) As the diameter increases, the downward force acting on the tape-shaped recording medium (1) increases;
3) Attach the magnetic head (the part with a larger diameter than the Q
502), the downward force is greater and the vertical movement of the tape-shaped recording medium (υ) is more effectively suppressed. Select the position of the mold gate so that the part has a large diameter. For example, when two magnetic heads (6) are installed at 180° intervals as shown in FIG. 2, gates may also be provided at 180° intervals as shown by gate portions (501) in FIG.

Note that this invention can be applied not only to the case where two magnetic heads (6) are installed, but also to the case where three or more (four are installed in the embodiment shown in Figure IJ3) as shown in Figure 3. However, in order to prevent rotational runout due to unbalance of the rotary cylinder (5A), it is necessary to select the position of the gate so that the large diameter portion is located at a symmetrical position with respect to the rotational axis of the rotary cylinder (5A). Needless to say, when cutting metal materials, the large diameter portion must be symmetrical.

〔Effect of the invention〕

As described above, according to the present invention, the vertical movement of the tape-shaped recording medium can be suppressed without damaging the tape-shaped recording medium, and the stable The effect of being able to perform recording and reproduction can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a rotary head assembly according to an embodiment of the present invention, FIG. 2 is a plan view of a rotary cylinder in the embodiment of FIG. 1, and FIG. 3 is a rotary cylinder in another embodiment of the present invention. FIG. 4 is a longitudinal sectional view showing a rotary head assembly of a conventional videotape recorder; FIG.
This figure is a front view of a conventional rotary head assembly and magnetic tape, and FIG. 6 is a perspective view of a conventional rotary cylinder molded with a molding material. In the figure, (1) is a tape-shaped recording medium, (ri is a fixed cylinder, (201) is a lead groove, (4 is a bearing, (5A)
is the rotating cylinder, (502) is the large diameter part, (f5
is a magnetic head. Note that the same reference numerals in each figure indicate the same parts or phase capsule parts. Agent Patent Attorney Masuo Oiwa Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Procedural amendment (voluntary)

Claims (2)

[Claims] (1) A fixed cylinder having a lead groove on its outer circumferential surface for guiding the tape-shaped recording medium, a rotating cylinder rotatably supported from the fixed cylinder via a bearing, and a rotating cylinder attached to the rotating cylinder to guide the tape-shaped recording medium. A rotary head assembly for a magnetic recording and reproducing device equipped with a magnetic head for recording and reproducing information, characterized in that the outer diameter of the rotary cylinder is larger in the vicinity of the magnetic head than in other parts. assembly. (2) In a rotary cylinder molded with a molding material, the large diameter portion formed near the gate of the mold of the rotary cylinder is located near the magnetic head, as set forth in claim 1. Rotating head assembly for magnetic recording and reproducing devices.