JPH03113861A - Rotary head device - Google Patents

Abstract

PURPOSE:To eliminate the filling up, etc., of a spiral groove, by communicating the space and external part of the internal part, providing a hole part for forming the blowing state of air with the sir being passed through from the external part into the internal part and providing a filter for powder dust at the inlet port of this hole part. CONSTITUTION:A pump out type spiral groove 27 is provided on the lower end face of the upper drum 23 as for the rotary drum fixed to a shaft 21 via the flange 22 fixed to the shaft 21. Holes 28, 29 communicating the space of the internal part and the external part are then provided and moreover filters 30, 31 for powder dust are provided respectively at the inlet ports of the holes 28, 29. The air sucked from the filters 30, 31 is blown out with the powder dust being removed there at. Thus the filling up, etc., of the spiral groove 27 can be eliminated.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a rotary head device suitable for use in, for example, a video tape recorder (VTR), and in particular to a method for forming an air film on the facing portion of a fixed drum and a rotating drum. This invention relates to a rotary head device provided with a spiral groove for the purpose of rotation.

[Summary of the invention]

This invention relates to a rotating head device that uses a drum provided with spiral grooves to obtain air blowing conditions, in which a space inside the rotating head device is rapidly passed through an outside space, and air is passed from the outside to the inside. A hole is provided to obtain air blowing conditions, and a dust filter is placed at the entrance of this hole to remove dust and eliminate clogging of the spiral groove. This is how it was done.

[Conventional technology]

Conventionally, for magnetic tape (hereinafter referred to as tape), 18
In a VTR equipped with a rotating head assembly configured to support a rotating drum that rotates and slides at 00 rpm and a fixed drum that does not rotate and slide, an opposing surface having a slight clearance between the fixed drum and the rotating drum is provided. established,
On the other hand, a so-called pump-out type spiral groove is formed on the surface of the drum to blow out air to float the tape, forming a uniform air film between the drum and the tape and establishing solid contact between the tape and the drum. Avoidance is being done. (Refer to Japanese Patent Application Laid-Open No. 1-37733.) Fig. 2 is a sectional view showing a conventional rotary head device disclosed in Japanese Patent Application Laid-Open No. 59-8160. ) is a flange fixed to this shaft, (
3) is an upper drum as a rotating drum fixed to the shaft [1] via this flange (2). (4),
(5) is a bearing that rotationally supports the shaft (1), (
6) is the lower drum as a fixed drum. Upper drum (
3) A pump-out type spiral groove (7) is provided on the lower end surface. (8) is a hole that communicates the interior space of the rotary head device with the outside.

Figure 3 shows the lower end surface of the above-mentioned upper drum (3).
A pattern of spiral grooves (7) is shown.

In the figure, a spiral groove is provided on a ring-shaped surface surrounded by two concentric circles with radii R, R2, and the shaded part (9) in the figure is the groove, and the white part is the land (10). It is. Further, (11) is a Herad chip, and (12) is a Herad base.

By rotating the upper drum (3) in the direction indicated by arrow a, the air inside the upper drum (3) is blown out.

The air blowing pressure at this time is expressed as follows.

However, in the above formula, Pa is the atmospheric pressure, μ is the viscosity coefficient of air, Cr is the clearance between the land (10) and the lower drum (6), ω is the angular velocity, R1 is the inner diameter of the upper drum (3),
R2 is the outer diameter of the upper drum (3).

In such a rotating head device, the air discharged to the outside by the spiral groove (7) provides a floating blade to the tape, causing the tape to slide on the outer peripheral surfaces of the upper drum (3) and lower drum (6). A uniform air film is formed over the entire moving part, avoiding sliding contact between the tape and the rotating head device, and realizing stable and smooth tape running.

[Problem to be solved by the invention]

By the way, in the conventional rotary head device as described above, it is known that reducing the clearance between the land (10) and the lower drum (6) will increase the amount of air discharged, as can be seen from the above formula. Therefore, if this clearance is further reduced, if the dust contained in the outflowing air is larger than this clearance, it will be caught between the land (10) and the lower drum (6), causing fluctuations in drum rotation and jitter. In the worst case, the rotation of the drum may stop, or in the long term, the grooves (9) may become damaged, reducing their performance.

The present invention has been made in view of these points, and it is an object of the present invention to provide a rotary head device that can eliminate the above-mentioned drawbacks.

[Means to solve the problem]

A rotary head device according to the present invention is a rotary head device that uses a drum provided with spiral grooves to obtain air blowing and blowing conditions, and the rotary head device communicates an internal space of the rotary head device with the outside. Holes (28, 29) are provided to allow air to pass from the inside to the inside to obtain an air blowout condition,
A dust filter (30, 31) is installed at the entrance of this hole.
It is arranged so that

[Effect]

In this invention, dust filters (30, 31) are provided in the holes that communicate the interior space of the rotary head device with the outside. This makes it possible to remove dust and eliminate clogging of the spiral groove, thereby eliminating deterioration of performance due to worsening of jitter, stoppage of rotation of the drum, or scratches on the groove.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIG.

1st TI! J shows a cross-sectional view of this embodiment, in which (21) is the shaft, (22) is the shaft (2).
1) is fixed to the flange, (23) is this flange (
The upper drum is a rotating drum fixed to the shaft (21) via a shaft (22). (24), (25)
is a bearing that rotatably supports the shaft (21), (26
) is the lower drum as a fixed drum. Upper drum (2
3) A pump-out type spiral groove (27) is provided on the lower end surface. (28), (29)
is a hole that communicates the interior space of the rotary head device with the outside.

In this embodiment, these holes (28) and (29)
Dust filters (30) and (31) are installed at the inlet of the
will be established. The clearance between the upper drum 23) and the lower drum (26) is usually about 20 μm. Therefore, the filter (
30) and (31) should not allow dust of 10 μm or larger to pass through, for example. Filter (30), (31)
Dust is removed from the air that has been sucked in more, and it is blown out along the thread paths shown by arrows 1 and 3.

This ensures that at least the upper drum (23) and lower drum (26)
) will not enter the drum, and dust will be caught between the upper and lower drums, causing fluctuations in drum rotation and jitter, or in the worst case, drum rotation will stop. This eliminates problems such as scratches around the grooves and deterioration of performance over a long period of time.

In the above embodiment, the holes (28) and (29) are provided in the lower drum (26), and a filter (30) is installed at the inlet of the holes (28) and (29).
, (31) were explained above, but holes (28) and (29) are provided in the upper drum (26),
A filter (30) at its inlet.

(31) may be arranged.

〔Effect of the invention〕

As explained above, the present invention provides a hole for communicating the interior space of the rotary head device with the outside to allow air to pass from the outside to the inside to obtain an air blowing state, and at the entrance of the hole. The provision of a dust filter has the effect of removing dust, eliminating clogging of the spiral grooves, and eliminating deterioration of performance due to deterioration of jitter, stoppage of drum rotation, or scratches on the grooves. be.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view showing a conventional example, and FIG. 3 is a view showing the lower end surface of the upper drum. (23) is the upper drum, (26) is the lower drum, (27) is a spiral groove, (28) and (29) are holes, and (30) and (31) are powder filters. Agent Hidemori Matsukuma Figure 1

Claims (1)

[Scope of Claims] A rotary head device that uses a drum provided with spiral grooves to achieve air blowing conditions, wherein an internal space of the rotary head device communicates with the outside to control the air blowing conditions. A rotary head device characterized in that it has a hole through which air passes from the outside to the inside in order to obtain dust, and a dust filter is disposed at the entrance of the hole.