JPH05258410A - Rotary head drum - Google Patents

Abstract

PURPOSE:To assure the life of a rotary drum and the stability of a head contact and to improve performance by providing spiral grooves for ejecting air flow on the outer peripheral surface of the drum. CONSTITUTION:Plural pieces of the spiral rugged grooves are provided on the surface of the rotary drum 1 facing a stationary drum 2. Namely, a part 1-b is a projecting part and a part 1-a is a recessed part. On the other hand, the surface of the stationary drum 2 facing the drum 1 is constituted of a plane 2-c in the region on the outlet side from the center of the tap, a thin wall 20d in the central position where the tape is wound on the inlet side of the tape and an opposite surface 2-b formed to the height lower than the height of the surface 2-c. The air is discharged to the outer peripheral surface of the drum 1 by centrifugal force when the drum 1 rotates. The supply of the air from the outside is executed through the opening hole provided on the drums 1, 2. The air forcibly guided in the hollow groove 1-a is discharged in an arrow direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary head drum of a helical scan type magnetic recording / reproducing apparatus,
Regarding high reliability.

[0002]

2. Description of the Related Art A structure in which a spiral groove is provided on either of the facing surfaces of a rotary drum and a fixed drum for ejecting air from the gap between the upper and lower drums is disclosed in Japanese Patent Laid-Open Publication No.
As described in Japanese Patent Publication No. 9-8160, the drum is provided over the entire circumference.

[0003]

The life of the head, the tape vibration due to the head hitting, and the tape vibration due to the sliding are mainly dominant from the center of the drum to the outlet. That is, since the tape tension is large at the drum outlet, the floating amount of the tape is small, and as a result, the contact force between the head and the cylinder and the tape is large. The configuration of the drum according to the above-mentioned conventional technology is a configuration in which air is ejected uniformly over the entire circumference of the drum. That is, the head life and tape vibration are reduced by forcibly lifting the tape from the drum. However, digital VTR, high-definition VT
In a system with a wide frequency band such as R, the cylinder rotation speed is large, so that the amount of tape floating at the drum entrance is large.
With the conventional drum configuration, the head at the drum outlet,
Although the contact force between the tapes is relaxed and the head life and tape vibration are reduced, on the contrary, the flying height of the tape at the drum entrance becomes too large, resulting in poor performance due to defective head contact. Therefore, it is necessary to have a drum structure in which air is ejected only in the tape winding region from the center of the drum to the outlet.

[0004]

In order to achieve the above-mentioned object, in a spiral shape in which air flows are jetted to the upper rotary drum by the rotation of the drum on the surfaces of the upper rotary drum and the lower fixed drum which face each other near the outer peripheral surfaces thereof. The groove is formed and the gap between the upper and lower drums is narrowed in the region from the center of tape winding to the outlet.

[0005]

The pressure p of the air flow ejected by the spiral groove provided in the upper rotary drum is larger as the distance between the upper and lower drum facing surfaces is smaller. The larger p is, the more the tape is pressed and the contact force between the head and the tape can be relaxed. Therefore, the gap between the upper and lower drums is set to be narrow from the central portion of the drum where the tape tension is high and the contact force between the head and the tape is large to the exit region, and the tape is forcibly floated.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a side view of a rotary drum of a magnetic recording / reproducing apparatus according to an embodiment of the present invention and shows a state in which a tape is wound. 2 is a plan view of a tape running system of the magnetic recording / reproducing apparatus, FIG. 3 is a longitudinal sectional view of a rotating drum, FIG. 4 is an exploded view of an upper drum and a lower drum, and FIG. 5 is a development between a gap between the upper drum and the lower drum. FIG. 6 is a schematic view of the air flow in one groove provided on the upper drum, FIG. 7 is a vertical cross-sectional view in which the tape is wound around the drum, and FIG. 8 is between the jet air pressure p and the upper and lower drums. The relationship with the gap, FIG. 9 is a schematic view showing the contact between the head and the tape at the drum outlet, FIG. 10 is the tape floating distribution around the drum, and FIG. 11 is the head life.
First, the configuration and operation of the magnetic recording / reproducing apparatus will be described with reference to FIG. 1 is a rotary drum, 3 is a tilt guide, 4 is a guide roller, 5 is a capstan motor, 6 is a capstan, 7 is a take-up reel, 8 is a supply reel, 9 is a pinch roller, 10 is a tension pin, 11 , 12 is a height regulation guide, and 13 is a tape. The tape 13 wound around the supply-side reel 8 is guided by the guides 11, 12, 4, and 3 by the capstan 6 and the pinch roller 9,
Drive in the direction. At this time, the drum 1 rotates in the direction A, and a plurality of heads mounted on the rotating drum (see FIGS. 3 and 4).
Recording and reproduction are performed according to the procedure shown in FIG. The tape 13 detects the tension by the tension pin 10 and controls the back torque to the supply side reel. (The tension control mechanism is not shown) Next, the structure of the rotary drum portion will be described with reference to FIG. 1 is a rotating drum, 2 is a fixed drum, 1
4 is a rotary transformer holder, 15 is a fixed shaft, 16
Is a yoke, 17 is a motor coil, 18 is a motor magnet, 19 is a magnet holder, 20 is a rotary transformer stator, 21 is a rotary transformer rotor,
22 is a head, 23 is a head base, 24 is a base fixing screw, 25 is a rotary drum fixing screw, 26 is a preload metal fitting, 2
7 is a ball bearing, and 28 is a disk. A fixed shaft 15 is vertically erected on the lower fixed drum 2, and a yoke 16 to which a motor coil 17 is fixed is adhered. Disk 2
Two ball bearings are press-fitted in 8 and are rotatable about the fixed shaft 15. A predetermined pressure is applied by the preload metal fitting 26 in order to suppress the play of the disk 28 in the thrust direction. (The method of fixing the preload metal fitting 26 to the fixed shaft 15 is not shown.) The rotor portion of the rotary transformer that transmits signals has the stator portion bonded to the rotary transformer holder 14 on the rotating drum and separated from a predetermined gap. The magnet 18 is shielded by a magnet holder 19 and fixed to the disc. The opposed motor coils are fixed to the fixed drum 2 and generate a rotational force of the motor by applying a predetermined voltage.

The feature of the present invention is that the rotary drum 1 and the fixed drum 2 on the opposing surfaces of the rotary drum 1 and the fixed drum 2 are the same.
Is the shape of. The above shape will be described with reference to FIG. 4, and the operation will be described with reference to FIGS.

A plurality of spiral concave and convex grooves are provided on the surface of the rotary drum 1 facing the fixed drum. Sunahachi, 1-
The portion b is a convex portion and the portion 1-a is a concave portion.

On the other hand, the surface of the fixed drum 2 facing the rotary drum 1 is a plane 2-c in the area from the center of the tape to the exit side and 2-d at the tape winding position on the tape entry side.
And a facing surface (2-b) formed at a height lower than the 2-c surface. As for the relationship of these surface heights, as shown in FIG. 5, the 2-d surface is separated from the rotating drum by δ ₁ , and the 2-b surface is separated by δ ₂ .

Next, the operation will be described with reference to FIG. When the rotary drum rotates, air is discharged to the outer peripheral portion of the drum by centrifugal force. Air is supplied from the outside through an opening hole provided in the rotary drum and the fixed drum. This opening hole is a field through hole for adjusting the posture of the head and for the signal line, and is not shown in the explanatory diagram. The air forcibly guided by the groove 1-a is discharged in the direction of the arrow as shown in FIG. This discharge air pressure p becomes larger as the gap δ ₁ between the convex 1-b surface of the rotating drum becomes smaller. Further, p becomes larger as the groove depth h becomes larger. This relationship is described in FIG.

If the gap δ ₁ is made too small, there is a limit because a serious problem of contact occurs due to variations in rotational accuracy between the rotary drum and the fixed drum. As described above, according to the present invention, the exhaust air pressure p is large on the drum outlet side. This is because the gap δ is configured to be large on the drum entrance side as described above. That is, since the gap between the facing surfaces on the inlet side is δ ₂ , the exhaust air pressure p is small.

Next, the operation will be described with reference to FIGS. 7, 9 and 10.

FIG. 7 is a sectional view showing a state where the tape is wound around the drum. The pressure p of the generated air flow forcibly presses the tape wound around the drum and relaxes the contact force of the tape with the drum. The wall provided as a 2-d portion from the drum is provided so that the tape wound around the drum does not enter the gap. If the gap becomes large, another problem occurs such that the tape is scratched at the edge of the gap and the tape running load increases. Since the gap between the fixed drum surface facing the rotary drum on the inlet side is large, the pressure p of the generated air flow is low. On the contrary, the pressure p of the air flow generated on the outlet side is high. The higher the pressure p, the larger the tape floating amount. This is the difference in the floating amount of the tape around the drum as shown by the dotted line and the solid line in FIG. The tape flying height for the conventional drum construction is shown by the dotted line, and the tape flying height for the drum construction according to the present invention is shown by the solid line. As can be seen from FIG. 10, according to the present invention, the floating amount of the tape around the drum is made uniform. The effect of this uniform flying height of the tape on the head contact will be described with reference to FIG. FIG. 9 shows the contact state between the tape and the head on the drum output side in comparison with the conventional case and the present invention. The tape tension on the drum outlet side is higher than that on the drum inlet side, and since the tape is helically wound around the drum, the contact area with the rotating drum that supplies air toward the drum outlet side is small and the air film is thin. Become. For this reason, the deformation of the tape wrapped around the head becomes large, and the contact force between the head and the tip of the tape becomes larger on the drum exit side. Generally, when the number of rotations of the drum is high, the amount of floating of the tape on the drum entry side is increased, and the head contact is easily deteriorated. For this reason, in order to reduce the amount of floating of the tape, a method such as providing a plurality of grooves that are discharge ports for air escape on the outer peripheral surface of the rotating drum is used, but the contact force between the head and the tape on the drum exit side is more than necessary. Will be large. This unnecessary increase in contact force promotes head wear, and the amount of protrusion of the head is reduced due to wear, which tends to deteriorate head contact performance. Equalize the floating amount of the tape around the drum to improve reliability.

[0014]

The effect of this embodiment will be described with reference to FIG. FIG. 11 shows the actual measurement results of the head scanning time and the head wear amount. According to the present invention, it is possible to reduce the amount of head wear in the set guarantee time of 1500 hours, so that the instability of the head tape contact depending on the tape tension fluctuation and the tape guide accuracy is reduced and the reliability of the performance is improved. .. In addition, the head life can be improved by reducing the head tape contact force.

[Brief description of drawings]

FIG. 1 is a side view of a rotary head device using the present invention.

FIG. 2 is a plan view of a rotary head device using the present invention.

FIG. 3 is a vertical cross-sectional view of a rotary head device using the present invention.

FIG. 4 is a perspective view of a rotary head device using the present invention.

FIG. 5 is a partial side view of a rotating and fixed drum of the rotary head device using the present invention.

FIG. 6 is an enlarged view of a rotary drum portion of a rotary head device using the present invention.

FIG. 7 is a vertical sectional view of a rotary drum portion of a rotary head device using the present invention.

FIG. 8 is a diagram showing the relationship between the clearance between the rotating and fixed drums and the exhaust air pressure in the present invention.

FIG. 9 is a vertical cross-sectional view of a tape around a head according to the related art and the present invention.

FIG. 10 is a distribution diagram of the amount of tape floating around the drum in the related art and the present invention.

FIG. 11 is a diagram showing changes over time in the amount of head wear in the related art and the present invention.

[Explanation of symbols]

 1 ... Rotating drum, 2 ... Fixed drum, 3 ... Tilt guide, 4 ... Guide roller, 5 ... Capstan motor, 6 ... Capstan, 7 ... Winding side Reel, 8 ... Supply side reel, 9 ... Pinch roller, 10 ... Tension pin, 11 ... Height regulation guide, 12 ... Height regulation guide, 13 ... Tape, 20, 21 ... Rotary transformer, 17 ... Motor coil, 18 ... Motor rotor, 19 ... Motor holder.

Claims (2)

[Claims] 1. A lower fixed drum having a lead portion for guiding a wound magnetic tape, and a recording medium which is arranged so as to be separated from the lower fixed drum while scanning the magnetic tape,
In a rotary head drum of a magnetic recording / reproducing apparatus including an upper rotary drum having a plurality of magnetic heads for reproducing, a drum is provided on a surface facing the lower fixed drum (2) of the upper rotary drum (1). A spiral groove (1) that discharges air from the inside of the upper rotating drum to the outside by the rotating operation.
The stepped portion (2-b, 2-c) is formed such that the gap between the upper rotary drum forming the part (a) and the upper rotary drum facing the lower fixed drum is narrowed at the magnetic tape winding outlet. A rotary head drum comprising a lower fixed drum provided. 2. The lower fixed drum (2) is substantially concentric with the facing surface facing the upper rotating drum (1), and
A step (2-) parallel to the rotating surface (1-b) of the rotating drum (1).
d) and the step (2-
b, 2-c), and the step formed on the inner peripheral side is configured such that the gap with the upper rotation facing surface is narrowed at the magnetic tape winding outlet. Rotating head drum.