JPS6346615A - Rotary head device - Google Patents

Abstract

PURPOSE:To obtain uniform and accurate spacing by providing a tape guide having a shape connecting the tip of a magnetic head and the circumferential face of a drum without any step to the part of a magnetic recording medium inlet of the magnetic head. CONSTITUTION:The magnetic head 6 is imbedded in a window 7 of an upper drum 1 by a resin 11 such as a silicon resin, a tape guide 12 is provided between the inlet of a video tape of the magnetic head 6 and the circumferential face of the upper drum 1 so as to eliminate the discontinuity of the boundary between the circumferential face of the upper drum and the video tape inlet of the magnetic head. Thus, the location of the minimum spacing is not deviated from the gap 8 toward the video tape exit due to the rigidity of the video tape and uniform and minute spacing is obtained between the magnetic head 6 and the video tape 4 near the gap 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotary head device having a rotary head on the circumferential surface of a rotary drum.

[Prior Art] Video tape recorders (hereinafter abbreviated as VTR) have been widely used as devices for recording and reproducing moving images.

A VTR uses the principle of magnetic recording to record image signals on a magnetic recording tape using a magnetic head, and has the advantage of being able to handle large amounts of image information easily and at low cost.

However, due to demands for higher image quality or longer recording times, V
The recording density by TR is becoming higher and higher. In addition, the so-called 8■■VTR, which has been developed as a smaller image recording system, has a higher resolution in order to ensure the amount of image information that can be recorded despite the decrease in recording area due to the miniaturization of cassette tapes. A high density Q density is required.

There are two methods for increasing the recording density (area density): narrowing the recording track by narrowing the width of the recording track, and shortening the wavelength by using even shorter wavelength signal components. In any case, as the recording area decreases by one wavelength, the signal voltage reproduced by the magnetic head also decreases, resulting in a decrease in S/N (signal-to-noise ratio).

Therefore, efforts have been made to improve the efficiency of the magnetic head and the characteristics of the recording medium in order to prevent the reproduction signal voltage from decreasing, but another major factor is the spacing between the head and the recording medium.

For example, the output decrease LS due to the presence of spacing during reproduction is expressed by the following equation.

LS = -54,6d/in (dB) (1) However,
d is the spacing amount and λ is the signal wavelength.

Currently, the signal wavelength used in VTRs is on the order of submicrons, so the amount of spacing has a significant effect on the reproduction output.

As a result, the spacing amount is now set to a very small value of around 0.1 gm.

Furthermore, since variations in the spacing amount are directly linked to output variations, it is necessary to set a stable and uniform spacing.

On the other hand, eliminating the spacing between the head and the medium and using the two in contact with each other causes wear on the medium sliding surface of the magnetic head, shortening the life of the head.

Furthermore, there are many problems with durability and reliability, such as changes in the shape of the head sliding surface due to wear, resulting in changes in spacing, and scratches on the head and medium.

Therefore, it is desirable that the head and the medium move relative to each other through minute spacing.

The structure of a conventional rotary head device used for this type of magnetic recording and reproducing is shown in FIGS. 9 to 14.

FIG. 9 schematically shows the running system of the video tape 4, which is a magnetic recording medium.

That is, an upper drum l having approximately the same diameter as the lower drum 2 is rotatably supported with a slight gap 3 between the fixedly arranged lower drum, and is driven by a predetermined drive source (not shown). rotated at rotational speed.

A window 7 is provided at the lower edge of the upper drum 1, and a magnetic head 6 is fixedly attached to the upper drum 1 in this window 7, and its sliding surface faces the outer peripheral surface of the upper drum 1. He is facing me. Note that FIG. 10 is an enlarged view of the portion indicated by the reference numeral 5 in the first figure.

When the upper drum 1 is viewed upside down, as shown in FIG. 11, the sliding surface 6a side of the magnetic head 6 protrudes from the outer peripheral surface side of the upper drum 1. In FIG. 11, the reference numeral 8 indicates a magnetic gap.

By the way, before explaining the operation of the rotary head having the above-described structure, the operation without the window 7 will be explained with reference to FIG. 12.

In FIG. 12, the reference numeral 9 is a rotating drum, which has a radius Rd and is rotated counterclockwise in the figure at a circumferential speed V, and the video tape 4 is wound around the rotating drum 10.

Further, at this time, it is assumed that the video tape 4 is in contact with the rotating rod 9 with a tension T.

In this state, first, when the rotating drum 9 is stationary, the video tape 4 is in contact with the rotating drum 9 while being wound thereon.

Next, when the drum 9 rotates once, since the air has viscosity, as the drum 9 rotates, the air is also dragged by the drum surface and moves.

As a result, an air flow is generated between the rotary drum 9 and the video tape 4 in the direction of rotation of the rotary drum, and the video tape is lifted off the circumferential surface of the drum.

That is, the rotating drum and the video tape move relative to each other by a certain distance Hd.

The distance ftHd at this time is given by the following equation.

In equation (2), extension is the viscosity of air.

However, if a window exists on the circumferential surface of the drum, the air flow between the drum and the videotape becomes uneven, and the flying height of the videotape also changes.

FIG. 13 shows the running state of the videotape when a window exists.

That is, the flying height Hdl of the video tape 4 in the portion located in front of the window 7 with respect to the rotational direction of the upper drum l is the same as the flying height in the case where there is no window, but the flying height Hdl behind the window 7 is
Hd2 is about one order of magnitude smaller than I(dl).

As a result, the height of the videotape 4 also decreases at the position corresponding to the window 7, and in some cases it is known that it becomes lower than the circumferential surface of the drum and sinks into the window.

The effect of the presence of a window on the flying height of a videotape occurs regardless of whether a head is attached to the window.

Therefore, in the conventional example shown in FIGS. 9 to 11, the flying height of the videotape was reduced due to the presence of the window.
This means that the protruding force of the magnetic head is increased by the amount of decrease, and as shown in FIG. growing.

As a result, the spacing between the magnetic helad 6 and the videotape 4 at the entrance side 9 of the videotape increases, and due to the rigidity of the videotape, the minimum spacing lO
The position of is shifted from gap 8 to the exit side of the videotape.

[Problems to be Solved by the Invention] When the spacing between the magnetic gap and the video tape as described above increases beyond the minimum spacing, there is a drawback that the output decreases and envelope defects occur.

[Means for Solving the Problems] In order to solve the above-mentioned problems in the rotary head device of the present invention, the tip of the magnetic head and the circumferential surface of the drum are provided at the portion of the magnetic head on the magnetic recording medium inlet side. We have adopted a structure with a tape guide that is shaped so that the two are continuous without any steps.

[Function] When the above-described structure is adopted, the magnetic recording medium is guided toward the magnetic gap along the tape guide, so that accurate and uniform spacing can be obtained.

[Example] Hereinafter, the present invention will be described in detail based on the example shown in the drawings.

In addition, in the two examples described below, FIGS. 9 to 1
The same parts as in FIG. 4 or corresponding parts are given the same reference numerals, and the explanation thereof will be omitted.

[First Embodiment] FIGS. 1 to 5 illustrate a first embodiment of the present invention, and show the upper drum 1 on which the magnetic head 6 is mounted upside down.

In this embodiment, the magnetic helad 6 is connected to the window 7 of the upper drum 1.
A resin 11 such as a silicone resin was embedded therein, and a tape guide 12 was provided using the resin 11 between the videotape entrance side portion of the magnetic head 6 and the circumferential surface of the upper drum l.

In order to obtain the above-mentioned structure, a window 7 is provided inside the upper drum l as shown in FIG. In addition to filling the space in the window, a tape guide 12 was formed on the tape entrance side of the head.

The effects of this embodiment will be explained using FIGS. 4 and 5. FIG. 4 is similar to the conventional example, and shows a running system consisting of an upper drum 1 and a video tape 4.

In the example shown in FIG. 4, as described above, the magnetic head 6 and the video tape 4 are
The pressure between

As a result, the spacing between the magnetic head 6 and the magnetic tape 4 becomes large on the video tape entrance side, and due to the rigidity of the magnetic tape, the position of the minimum spacing shifts from the gap 8 to the video tape exit side, and the gap 8, the result was that the minimum spacing could not be obtained.

On the other hand, in this embodiment, as shown in FIG.
A tape guide 12 is provided on the video tape entrance side of the upper drum 1 and the magnetic head 6 to eliminate discontinuity at the boundary between the circumferential surface of the upper drum and the video tape entrance side of the magnetic head.

By doing this, the effect is similar to that of increasing the radius of curvature of the magnetic head, and compared to the conventional example, there is a gap between the magnetic head 6 and the magnetic tape 4 at the entrance side of the video tape of the magnetic head 6. The air pressure does not increase.

As a result, the spacing becomes larger at the entrance side of the videotape, and the position of the minimum spacing does not shift from gap 8 to the exit side of the videotape due to the rigidity of the videotape, as seen in the conventional example. , a uniform and minute spacing is obtained between the magnetic head 6 and the video tape 4 in the vicinity of the gap 8.

Since this embodiment is configured as described above, a uniform and minute spacing between the video tape and the magnetic head can be obtained near the gap between the magnetic heads, and a stable and large output can be obtained compared to the conventional method. .

Furthermore, since there is no window itself on the drum, it is possible to eliminate scratches on the medium caused by the corners of the window provided on the upper drum and the videotape, which has been a problem in the past.

[Second Example 1 A second embodiment of the invention is shown in FIGS. 6-8.

In this embodiment, the magnetic helad 6 is connected to the tape guide 13.
When it is attached to the chip base 13 having a tape guide 13a on the video tape sliding surface side and fixed to the window 7 made by processing the upper drum as shown in FIG. 6, the structure shown in FIG. 8 is obtained. The part will come.

Since this embodiment is configured as described above, it has the advantage that the complexity of resin molding can be omitted and productivity is improved compared to the first embodiment.

Although the tape guide 13a of the chip base 13 is straight as shown in the drawing, it is of course possible to use a smooth curve.

[Effects] As is clear from the above explanation, according to the present invention, a structure in which a tape guide is provided at the tape entrance side of the magnetic head of the rotating drum is adopted, so that more stable and higher output can be obtained. This can reduce damage to magnetic recording media (video tapes) and extend the life of the media.

[Brief explanation of drawings]

Figures 1 to 5 explain the first embodiment of the present invention, with Figure 1 being a perspective view of the drum, Figure 2 being an enlarged plan view of the upper drum before being filled with resin, and Figure 3 being an enlarged plan view of the upper drum before being filled with resin. FIG. 4 is an enlarged plan view of the upper drum filled with resin, FIG. 4 is an enlarged plan view of the traveling system in the comparative example, FIG. 5 is an enlarged plan view of the traveling system of the first embodiment, and FIGS. 6 to 8 are Embodiment 2 of the present invention is explained, and FIG. 6 is an enlarged perspective view of the upper drum, FIG. 7 is an exploded perspective view of the head portion, FIG. 8 is an enlarged perspective view of the upper drum, and FIG. 9 is an enlarged perspective view of the upper drum. ~Figure 14 explains the conventional structure, Figure 9 is a perspective view of the traveling system, Figure 10 is an enlarged view of the vicinity of the magnetic field 2,
Figure 11 is a perspective view showing how the magnetic head is installed, Figure 12 is a perspective view of the running system when there are no windows or heads on the drum, and Figure 13 is a running system consisting of a drum with a window and tape. The plan view of FIG. 14 is an explanatory diagram of the running state. l...Upper drum 4...Video tape 6...
・Magnetic head 7...Window 8...Magnetic gap ll...Resin 12.13a
...Tape guide 13...Chip base

Claims (1)

[Scope of Claims] 1) A rotary head device that rotates a rotary drum having a magnetic head fixed to its circumferential surface and performs electromagnetic conversion between a magnetic recording medium wound around the drum and the magnetic head,
A rotary head device characterized in that a tape guide is provided at a portion of the magnetic head on the magnetic recording medium entrance side, the tape guide having a shape that connects the tip of the magnetic head and the circumferential surface of the drum without any step. 2) The tape guide is provided on a head base to which the magnetic head is fixed, and the head is fixed to the drum via the head base. Rotating head device.