JPH01303664A - Rotary head device - Google Patents

Abstract

PURPOSE:To minimize the wear of a magnetic head and the rotation load of a cylinder and to eliminate the damage of the magnetic tape by providing continuously the level difference in the diameter direction of an outer circumferential surface of a rotation cylinder and a fixed cylinder. CONSTITUTION:A rotation cylinder 8 is rotated for a rotation center 2a, the cylinder center of the magnetic tape sliding part of a fixed cylinder 9 is decentered for a rotation center 2a of a rotation cylinder, the level difference in the diameter direction of the outer circumferential surface of the rotation cylinder 8 and the fixed cylinder 9 is continuously changed from a contact starting edge C to a contact termination D of the magnetic tape and cylinders 8 and 9 and the level difference becomes larger as a termination part is approached. Consequently, the increase in the tension of the magnetic tape can be suppressed, the excessive load is not received by a cylinder part and the magnetic tape, and the stable tape travelling is executed. Thus, the wear of the magnetic head and the rotation load of the cylinder 8 are minimized and the generation of the damage of the magnetic tape can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a rotary head device used in a rotary head type magnetic recording/reproducing device or the like.

2. Description of the Related Art Conventionally, a rotary head device for a rotary head type magnetic recording/reproducing apparatus is disclosed in, for example, Japanese Patent Application Laid-Open No. 60-45968.

FIG. 4 is a sectional view showing a conventional rotary head device.

In A of the figure, a cylindrical rotating cylinder 8 and a fixed cylinder 9 with a certain diameter difference are supported on the same shaft 10, and a magnetic head 11 is integrally provided with the rotating cylinder 8. It is configured to rotate relative to a bearing 12.

FIG. 6 is a plan view showing the relationship between the cylinder and the magnetic tape. The magnetic tape 3 is wound around the cylinder 1 rotating in the input direction by a constant angle θ from the contact start point C to the contact end point with the cylinder 1, and is rotated at a constant speed. and drive in direction B.

FIG. 6 shows a side view of the cylinder and magnetic tape. The magnetic tape 3 runs helically relative to a rotating cylinder 8 and a stationary cylinder 9.

The rotating cylinder 8 rotates at high speed in the direction of the arrow, and there is air lubrication between the magnetic tape 3 and the rotating cylinder 8, while the fixed cylinder 9 and the magnetic tape 3 are in sliding contact. The situation of contact with the magnetic tape is different for cylinders that are fixed, rotary, and fixed.

The behavior of the magnetic tape on a rotary head type cylinder having such a configuration is complicated. That is, at the starting end of the contact between the magnetic tape and the cylinder, the force of the rotating cylinder pulling the magnetic tape in the direction of cylinder rotation is strong, and as it approaches the terminal end, the influence of sliding friction between the magnetic tape and the fixed cylinder increases.

FIG. 7 shows the change in tension of the magnetic tape from the contact start point C of the magnetic tape and the cylinder to the end point.

The influence of the rotating cylinder is large near the starting end.

The tension of the magnetic tape decreases once from the tension before entering the cylinder, and then the influence of friction with the fixed cylinder increases and the tension increases. The relationship between this change in tension changes when the diameter difference between the rotating and fixed cylinders is changed; when the diameter difference is large (h), the tension decreases markedly, and conversely, when the diameter difference is small (f). case) The tension tends to increase.

Furthermore, it has been experimentally confirmed that the magnitude of the load applied from the magnetic tape to the magnetic head is approximately proportional to the tension of the magnetic tape.

Problems to be Solved by the Invention However, the following problems arise with the conventional cylinder structure.

In order to obtain good magnetic head output, it is necessary to minimize the gap between the magnetic head gap and the magnetic tape to minimize magnetic loss during recording and playback. It is necessary to provide stable contact between the magnetic head and the magnetic tape. In particular, near the start of contact between the magnetic tape and the cylinder, vibrations caused by the collision between the magnetic head and the magnetic tape and deformation of the magnetic tape in the width direction due to the tape running system are strong, and the behavior of the magnetic tape becomes unstable. In order to prevent this, it is necessary to apply sufficient tape tension and to minimize the difference in diameter between the upper and lower cylinders to minimize the drop in tension.

However, as mentioned above, at the end of contact between the magnetic tape and the cylinder, if the difference in diameter is small, the tension of the magnetic tape is higher than at the start end, and more load than necessary is applied to the magnetic head and cylinder than the magnetic tape.

In such situations, increased wear on the magnetic head,
Problems such as increased rotational load on the cylinder and damage to the magnetic tape occur.

In view of the above-mentioned problems, the present invention reduces the change in the tension of the magnetic tape between the start and end of contact between the magnetic tape and the cylinder, thereby reducing the wear of the magnetic head and the rotational load on the cylinder. To provide a rotating head device which eliminates tape damage.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a cylinder unit consisting of a rotating cylinder that rotates together with a magnetic head and a fixed cylinder, in which the center of the tape sliding cylindrical portion of the fixed cylinder is , by being eccentric with respect to the axis of the rotating cylinder, the radial step of the outer circumferential surfaces of the rotating cylinder and the fixed cylinder is continuously changed from the start of contact between the magnetic tape and the cylinder to the end of contact, and as it approaches the end, , the rotating and fixed cylinders have a large step difference.

Effect of the Invention With the above-described configuration, the present invention keeps the step in the radial direction of the outer circumferential surface of the rotating and fixed cylinder small near the starting end of contact between the magnetic tape and the cylinder, and reduces the step in the outer circumferential surface of the rotating and fixed cylinder toward the terminal end. By making it larger, it is possible to suppress an increase in the tension of the magnetic tape, and stable tape running can be performed without subjecting the cylinder section or the magnetic tape to an undue load.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

Figure 1 shows a digital model using a cylinder with a diameter of 15 mm.
FIG. 2 is a plan view showing an example of a tape running path of an audio tape recorder (DAT). In the figure, a cylinder 1 is rotating about an axis 2 in the direction of an arrow A at a speed of 2000 revolutions per minute. After being pulled out from a cassette (not shown), the magnetic tape 3 is driven in the direction of arrow B by a capstan and a pinch roller (not shown), passes through a guide post 4.5, and is attached to a cylinder at a 180° angle. It wraps around, passes through the guide post 6.7, and returns to the cassette.

FIG. 2 is a plan view showing the shape of the seal of the present invention. In the figure, the rotating cylinder 8 rotates about the rotation center 2a and has a cylindrical shape with a radius of 7.6+αman.

The magnetic tape sliding part (broken line part) of the fixed cylinder 9 has a cylindrical shape with a radius of 7.6 + β mm, and the center of the cylinder is shifted by γ from the rotation center 21L of the rotating cylinder in the direction of the contact start end C with the magnetic tape. At point 0, the distance from the center 2a to the outer circumference of the fixed cylinder is (7,5 + β + γ)
mm, and the distance decreases continuously toward the end, and becomes (7,6+β-γ)+n+n near the end.
become.

! Here, α>β+γ.

In other words, the difference in the radial direction between the outer circumferential surfaces of the rotating cylinder and the fixed cylinder is greater than (α-β-γ) at the starting end than (α-β-γ) at the terminal end.
−β+γ).

FIG. 3 is a diagram showing the change in the tension of the magnetic tape in the cylinder with the above-described configuration. case).

The tension change is almost the same near the starting end of the contact between the magnetic tape and the cylinder, but there is a difference toward the end, and in the cylinder of the present invention (case b), the increase in the magnetic tape tension is small.

Effects of the Invention As described above, according to the present invention, by continuously providing steps in the radial direction on the outer circumferential surfaces of the rotary cylinder and the fixed cylinder, the magnetic head can be prevented over the entire contact range between the cylinder and the magnetic tape. The magnetic tape is in stable contact with the cylinder, and even if sufficient tension is applied to the magnetic tape, the increase in tension on the magnetic tape is kept to a minimum even near the end of contact between the cylinder and the magnetic tape. As a result, the load from the magnetic tape on the cylinder and magnetic head is reduced compared to conventional cylinders.
This not only improves the lifespan and reliability of the cylinder and magnetic head, but also reduces the load on the mechanism, reduces driving force, and saves energy.

It is also effective in preventing damage to magnetic tape.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a DAT running path according to an embodiment of the present invention, FIG. 2 is a schematic diagram of a cylinder of the present invention, and FIG. 3 is a diagram showing tension changes on a cylinder of a magnetic tape according to the present invention. , Fig. 4 is a configuration diagram of a conventional cylinder, Fig. 5 is a top view of the relationship between the cylinder and magnetic tape, Fig. 6 is a side view of the relationship between the cylinder and magnetic tape, and Fig. 7 is a diagram of the magnetic tape on the cylinder in the conventional cylinder. FIG. 1...Cylinder, 3...Magnetic tape,
8... Rotating cylinder, 9... Fixed cylinder, 11... Magnetic head. Name of agent: Patent attorney Toshio Nakao and 1 other person/-
--Silin 1st figure / 8-1st iris turn 2nd figure 3 (Takashi 19 Cheeve meal A scrap
α (Shima b) 8-p beast cylinder. 9--One round cylinder tO--One glaze/---Sissonda

Claims (1)

[Claims] In a rotary head device comprising a rotary cylinder that rotates together with a magnetic head and a fixed cylinder, and in which a magnetic tape is wound around the rotary cylinder and the fixed cylinder at a predetermined angle and travels, the rotation center of the rotary cylinder is moved from the rotation center of the rotary cylinder to the fixed cylinder. The cylindrical portion of the fixed cylinder is provided eccentrically with respect to the rotation axis of the rotary cylinder such that the distance to the cylindrical outer peripheral portion of the fixed cylinder decreases continuously from the contact start end to the contact end with the magnetic tape. A rotating head device characterized by: