JPS59207455A - Rotary head assembly - Google Patents

Abstract

PURPOSE:To improve signal input/output characteristics by forming a pressure leakage structure at a part on a lower fixed cylinder and controlling the float- up degree of a tape. CONSTITUTION:A rotary head assembly contains a rotary cylinder 10, an air pressure leakage groove 11 formed on a fixed cylinder 12, a magnetic tape 13, etc. The groove 11 is set at the vicinity of the input side of the tape driving surface of the cylinder 12. A spiral group is formed on the lower edge surface of the cylinder 10. Then the float-up of the tape 13 is promoted from the cylinder by the air jetted through a gap 14 formed between cylinders 10 and 12. This assembly improves smooth contact between a magnetic head and the magnetic tape and therefore improves the signal input/output characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a rotating head assembly for a videotape recorder (hereinafter abbreviated as VTR).

Conventional configuration and its problems As a representative example, Vf (S-type VT, H) will be explained.

A conventional rotary head assembly (r''i), as shown in FIG. A fixed cylinder 3 is used as a supporting component.A lead 4 is provided on the fixed cylinder 3 for the purpose of regulating the position of the tape 10 when it runs.A magnetic lead 4 mounted on the rotating cylinder 2 The accurate helical scanning of the helical cylinder 5 over the tube 1 realizes reliable input and output of the video signal via the tape 1. However, the tape 1 is almost in contact with the fixed cylinder 3. Since the tape 1 moves and travels, it is subjected to dynamic frictional force. Especially when the VTR is used in a high humidity atmosphere or under conditions of rapid temperature changes, microscopic water droplets may cause damage to the tape 1 and the fixed cylinder 3. Condensation occurs between the tape 1 and the fixing cylinder 3, forming a thin water film of several hundred to several thousand angstroms.The viscous resistance of the water caused by the presence of this water film causes the tape 1 and the fixing/linda 3 to completely adhere to each other. In many cases, a type of self-excited vibration is excited on the tape side due to intermittent adhesion phenomena.

In the above case, accurate input/output of video and audio signals via the tape cannot be expected, and the performance of the VTI (VTI) is significantly degraded or becomes completely unusable.

In addition, in FIG. 1, 6 is a tape running guide post;
Arrow A indicates the tape running direction, and arrow B indicates the direction of rotation/rotation of the cylinder 2. (Arrows to arrows and arrow B are common to all figures.) On the other hand, due to the need to develop a small and lightweight type of VER, improvements in magnetic recording density are required on the tape side. In other words, there is a trend in tapes from conventional ferrite or chromium dioxide magnetic powder coated with a resin binder to metal tapes with a nickel-cobalt alloy deposited or coated on a resin base. . In this case, the sliding state of the metal tape with respect to the mating cylinder becomes metal-to-metal sliding, and the relative coefficient of friction becomes higher, making it difficult to ensure stable tape running.

Therefore, in order to eliminate the above-mentioned drawbacks, the present inventors developed a second
．． A new type of rotary head assembly having the configuration shown as a representative example in FIG. 3 has already been proposed. This is activated by the spiral group 6 provided in a specific part of the rotary cylinder 2 or the fixed cylinder 3, or by the rotation of the rotary cylinder 2, and by generating dynamic pressure, the rotary cylinder 2 and the fixed cylinder 3 Tape 1 is placed in a small amount (approximately 5 to 1
0 μ771) floating” and only the magnetic head 5 is connected to the tape 1.
It was designed to make contact with This invention greatly improves the tape sliding characteristics of the rotary nodule assembly, thereby stabilizing tape running, eliminating self-excited vibrations, and significantly improving signal characteristics when running under environmentally resistant conditions. This has the remarkable effect of suppressing wear and deterioration of both the paralytic rotating head assemblies.

In Fig. 2, 7 is a rotating shaft and 8 (a bearing d).However, when the tape is held floating in the rotating head assembly of the new configuration, ``particularly when the tape starts to wrap around the rotating head assembly. 9 (hereinafter referred to as the entrance side), as shown in Fig. 4, most of the tape surface hangs over the rotating cylinder 2, and the tape runs along a small portion of the fixed cylinder. Since the head is pushed up from below at the upper end in the tape width direction, the floating tape easily tilts and deforms, making it impossible to ensure proper contact between the head and the tape.For this reason, the rotating head The signal input/output characteristics on the input side of the assembly deteriorate.On the other hand, at the end of winding the tape onto the rotating head assembly (hereinafter referred to as the output side), conversely, most of the tape hangs on the fixed cylinder and the head passes through the upper end of the tape width direction and leaves the tape.In this case as well, the symbol input/output characteristics on the output side of the rotating head assembly will deteriorate, or
Normally, the extent of this is not too bad on the entry side. This difference is considered to be due to the difference in mechanism between when the head enters into contact with the tape from the air and when it leaves the contact state.

In this way, when a structure is adopted in which the tape is floated and held on a rotating head assembly provided with a spiral group, it is necessary to locally reduce the tape flying height from the viewpoint of the head touching the tape.

Purpose of the Invention In view of the above-mentioned drawbacks, the present invention provides a pressure leak structure locally on the lower fixing/slider to control the tape flying height, and to control the signal input/output characteristics for all tapes on the rotating head assembly. 62. A rotary head assembly is provided.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 5 shows a perspective view of a rotating head assembly in a first embodiment of the invention. In Figure 5,
10 is a rotary cylinder, 11 is a pneumatic leak groove provided in the fixed cylinder 12, 13 is a magnetic tape, and the pneumatic leak bay 11 is provided on the entrance side of the tape running surface of the fixed cylinder 12, for example. It may be something like a D cut. Similar to the conventional example shown in FIGS. 2 and 3, a spiral group is formed on the lower end surface of the rotating cylinder 10, and a gear between the rotating cylinder 10 and the fixed cylinder 12,
The rotary head assembly configured as described above has a structure that promotes the floating of the magnetic tape 13 from the cylinder by air discharge from the cylinder 14.
The operation will be explained below.

As the rotary cylinder 10 rotates, the /ζ spiral group formed on the lower end surface of the rotary cylinder 10 maintains a speed of 1 point between it and the opposing m1, and dynamic pressure is generated here, and the magnetic tape 13 floats several to several tens of microns above the cylinder, which releases the air trapped between the magnetic tape 13 and the tape running surfaces of the rotating cylinder 10 and fixed cylinder 12 to the atmosphere. The air pressure for floating the tape 13 is reduced, and the flying height can be reduced. Figure 6.

FIG. 7 is an explanatory diagram showing the relative positional relationship between the air pressure leak groove 11 and the magnetic tape 13 in the first embodiment of the present invention. FIG. 6 shows the rotating cylinder 10 and the magnetic tape 13.
7 is a view seen from above, and FIG. 7 is a view taken along arrow C in FIG. 6.

As described above, according to this embodiment, the contact between the magnetic head and the magnetic tape is relatively difficult to ensure, and the flying height of the tape is reduced only in the vicinity of the entrance side, thereby improving the contact between the magnetic head and the magnetic tape. , signal input/output characteristics can be improved.

A second embodiment of the present invention will be described below with reference to the drawings.

FIG. 8 shows a second embodiment of the invention. In FIG. 8, 16 is a ventilation hole. The vent hole 16 is provided at the same position as the air pressure leak hole 11 in the first embodiment, communicates with the inside of the rotary head assembly, and is connected to the rotary cylinder 10.
The magnetic tape 13 is held between the tape running surface of the fixing/cylinder 12 and the fC air is released to the entire atmosphere.
The air pressure that makes it levitate decreases. Ventilation hole 16 (first
This is provided as a replacement for the pneumatic groove 11 in the second embodiment, and the other features are exactly the same as in the first embodiment.

Regarding the rotating head assembly configured as above,
The operation will be explained below.

FIG. 9 is an explanatory diagram showing the relative positional relationship between the ventilation hole 16 and the magnetic tape 13 in the second embodiment of the present invention.

FIG. 9+d is a view seen from arrow C in FIG. 6.

In FIG. 9, near the entrance side, the magnetic tape 13
In order to release the air trapped between the tape running surface of the rotary cylinder 10 and fixed cylinder 12 to the atmosphere,
The air pressure for floating the magnetic tape 13 is reduced, and the amount of float can be reduced.

As described above, according to this embodiment, it is relatively difficult to ensure that the magnetic head and the tape are aligned to the west, and the tape floats only near the entrance side.
It is possible to reduce the amount of noise and improve the signal input/output characteristics.

In the above embodiments, the method in which the spiral group 6 is provided in a specific part of the rotary cylinder 2 or the fixed cylinder 3 has been described, but it is also possible to apply a method in which the spiral group 6 is not provided. Not even 1.

Effects of the Invention As described above, the present invention provides air pressure leak grooves or ventilation holes near the entrance side of the outer circumferential surface of the fixed cylinder, so that contact between the magnetic head and the tape can be relatively easily ensured. It is possible to reduce the amount of tape floating only in the vicinity, improve the contact between the magnetic head and the tape, and improve signal input/output characteristics.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a conventional rotary head assembly, Fig. 2 is a sectional view of a conventional air-discharged tape floating type rotary head assembly, Fig. 3 is a perspective view of a rotary cylinder, and Fig. 4 is a conventional rotary head assembly. A perspective view of the head assembly, FIG. 5 is a perspective view of the head assembly according to the first embodiment of the present invention, a perspective view of the head assembly, FIG. 6 is a side view, and FIG. FIG. 8 is a front view of the rotary head assembly showing the relative positional relationship between the air pressure leak groove and the tape near the inlet and outlet sides; FIG. 8 is a perspective view of the rotary head assembly in the second embodiment of the present invention; FIG. The figure is a half-view of the rotary head assembly showing the relative positional relationship between the pneumatic leak tube and the tape near the entrance and exit sides of the rotary head assembly in the second embodiment of the present invention. 10...Rotary cylinder , 11...Pneumatic leak groove, 12...Fixed sill, 13...Magnetic tape, 14...Gap portion, 15...Head mounting window, 16...Vent hole. Substitute Name of person Patent attorney Toshio Nakao and 1 other person 1st
Figure 2 Figure 4 Figure 5

Claims (1)

[Claims] a lower fixed cylinder, an upper rotating cylinder having approximately the same diameter as the lower fixed cylinder and coaxially arranged with a gap therebetween, and fixed near the outer periphery of the upper rotating cylinder; It is composed of a lower fixed cylinder and a magnetic head that rotates about the same axis, and has an air pressure leak groove or a passage at least at the outer circumferential surface of the lower fixed cylinder and at the magnetic tape winding start part of the outer circumferential surface of the lower fixed cylinder. Rotating head assembly with pores.