JPH05182312A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To always maintain a specified air film thickness and to surely obtain a good recording and reproducing state by varying the groove width of a rotary drum even if the rotating speed of the rotary drum is changed. CONSTITUTION:The rotary drum 1a fixed with a magnetic head 3 projected from the peripheral surface in the bottom end is divided to a plurality above and below in the parts of variable width grooves 5. The respective divided pieces provide bottoms in the variable with grooves 5 by hermetic closing means consisting of concentrical groove 1f and projecting parts 1g. In addition, these pieces are coupled and held by laminated piezoelectric elements 6 and are so constituted that variable width grooves 5 are controlled to be widened when the rotating speed of the rotary drum 1a is high and the variable width grooves 5 are controlled to be narrowed when the rotating speed of the rotary drum 1a is low by the voltages impressed to the laminated piezoelectric elements 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus using a rotary drum, and more particularly to means for ensuring stable tape running during high speed running.

[0002]

2. Description of the Related Art In recent years, when recording, the signal frequency, tape speed, and drum rotation speed are set to several times faster than during reproduction.
A helical scan type magnetic recording / reproducing apparatus has been developed in which, during reproduction, the tape speed and the drum rotation speed are set to a normal low speed to obtain a clear slow-motion reproduction image.

Generally, in a helical scan type magnetic recording / reproducing apparatus, a magnetic tape is wound around a guide drum to run, and a magnetic head mounted on a rotating drum scans the surface of the magnetic tape at high speed to record a signal. Or play it. FIG. 6 is a side view showing the entire guide drum of a conventional magnetic recording / reproducing apparatus. The guide drum is an upper cylindrical rotating drum 1 and a lower cylindrical rotating drum 1 that rotatably supports the rotating drum 1 at a predetermined interval. It consists of a fixed drum 2.

A magnetic head 3 is attached to the window 4 at the bottom of the rotary drum 1, and a groove 9 is formed on the outer circumferential surface of the rotary drum 1 in the circumferential direction of rotation. FIG. 7 is a top view of FIG. FIG. 8 shows a cross-sectional view of the OB cross section of FIG.
The head 3 fixedly attached to the rotary drum 1 is fixed to the rotary drum 1 with screws. 9 and 10 are partial side views of FIG. 6, showing the positional relationship of the magnetic tape 10 with respect to the rotating drum 1 and the magnetic head 3 while the rotating drum 1 is rotating. FIG. 9 shows the tape 10 when the width of the groove 9 is large and the drum rotation speed is low.
-Shows the positional relationship between the rotating drum 1 and the fixed drum 2. Figure 1
0 is the tape 10 for the rotating drum 1 and the fixed drum 2 when the width of the groove 9 is small and the drum rotation speed is high.
The positional relationship of is shown. 9 and 10, the cross-section of the tape 10 is shown by enlarging the relational dimensions with respect to the drum 1a as compared with the other portions.

In the above structure, a laminar flow of air (air film) is formed between the outer peripheral surface of the guide drum and the magnetic tape 10 by the rotation of the rotary drum 1.
In order to prevent the air film from hindering the good contact of the tape head, a groove 9 for reducing the air film is formed on the outer peripheral surface of the rotary drum 1.

If the width of the groove 9 is small, the thickness of the air film becomes large at the entrance side of the rotary drum 1 where the tape 10 is wound around the rotary drum 1 with a large winding width, so that the head 3 can hit the tape 10 well. It is not secured and the head output is lost. On the other hand, if the width of the groove 9 is too large, the air film between the tape and the rotary drum disappears, and the tape 10 comes into contact with the rotary drum 1, causing problems such as tape damage. Therefore, the width of the groove 9 is optimally set according to the rotation speed of the rotary drum.

[0007]

However, when recording, the rotational speed of the rotary drum is set to a high speed (for example, 5400 rpm), and when the reproduction is performed, the rotational speed of the rotary drum is set to a low speed (for example, 1800 rpm) to perform a clear slow reproduction. You may get a motion image. At this time, if the groove width is optimized to prevent tape damage due to contact between the tape and rotating drum during playback, the air film between the tape and rotating drum will become too large during recording, and sufficient contact between the tape and head will be obtained. The signal is not recorded on the tape and the head output is lost during playback.

The present invention has been made to eliminate the above-mentioned conventional problems, and an object of the present invention is to provide means for providing an optimum air film thickness to the rotational speed at that time even if the rotational speed of the rotary drum is changed. And

[0009]

In order to achieve the above object, the present invention provides a fixed drum, a rotary drum that is rotatably supported by the fixed drum, and a variable width in the circumferential direction on the outer peripheral surface of the rotary drum. In a guide drum having a groove and a magnetic head protruding from the window of the rotary drum, the groove width of a variable width groove circumferentially formed on the outer peripheral surface of the rotary drum is controlled according to the number of rotations of the drum. It has a variable mechanism.

[0010]

With the above structure, the magnetic recording / reproducing apparatus of the present invention is
By making the groove width of the variable width groove on the outer peripheral surface of the rotating drum variable according to the number of rotations, a groove width corresponding to each high-speed / low-speed rotation can be created to prevent contact between the rotating drum and the tape, and a good tape head Contact at each rotation speed.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure and operation of a magnetic recording / reproducing apparatus according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is an external side view showing the configuration of the guide drum. The guide drum is a cylindrical rotary drum 1a having a mechanism for varying the upper groove width, and a lower cylindrical drum that rotatably supports the rotary drum 1a at a predetermined interval. It consists of a fixed drum 2. Rotating drum 1
The magnetic head 3 is fixed to the window portion 4 at the bottom of a so as to project. A variable width groove 5 having a variable width in the circumferential direction of rotation is formed on the outer peripheral surface of the rotary drum 1a.

FIG. 3 is a top view of FIG. Multilayer piezoelectric element 6 that is a control element for varying the groove width, arranged every 120 degrees
The position of is shown. FIG. 1 is a cross-sectional structural view of the 0A cross section of FIG. The rotary drum 1a is divided into four parts 1b, 1c and 1d with the variable width groove 5 as a boundary. Each portion has a concentric circular groove 1f on the lower surface slightly inside the outer circumference, and has a concentric circular convex portion 1g as a sealing means on the surface of the other piece facing the groove 1f. The individual pieces 1b to 1e can slide up and down by sliding the 1f and the convex portion 1g together. Therefore, the variable width groove 5 has a constant depth even if its width changes. And each piece 1b to 1e is
It is connected and held by the laminated piezoelectric element 6. The laminated piezoelectric element 6 has a lead wire 7 and is controlled from the VTR circuit section by a brush, a slip ring or the like. Although not shown because the individual pieces 1b to 1e freely slide up and down, a through hole for circulating the internal air may be provided.

FIG. 4 shows the positional relationship of the tape 10 with respect to the rotating drum 1a and the fixed drum 2 when the groove width is small and the drum rotation speed is low. FIG. 5 shows the positional relationship of the tape 10 with respect to the rotary drum 1a and the fixed drum 2 when the width of the variable width groove 5 is large and the number of rotations of the drum is high. In both FIGS. 4 and 5, the tape 1 is the same as in FIGS.
The cross section of 0 shows the relational dimension with respect to the drum 1a in an extremely enlarged manner as compared with the other portions.

When the rotation speed of the rotary drum is low, the height of the laminated piezoelectric element 6 shown in FIG. 3 is reduced to reduce the width of the variable width groove 5 as shown in FIG. 4 to optimize the air film amount. And keep good contact with the tape head.
Further, when the number of rotations of the drum is high, the height of the laminated piezoelectric element 6 shown in FIG. 3 is increased by the control signal from the VTR circuit unit, and as shown in FIG.
Becomes wider. This reduces the air film between the rotating drum 1 and the tape 10 to an appropriate degree and keeps the tape head in good contact. In this way, by controlling the laminated piezoelectric element 6 of FIG. 3 according to the rotation speed of the rotary drum 1,
It is possible to generate a groove width according to the number of revolutions and keep the thickness of the air film constant without being influenced by the number of revolutions, so that the tape 10 can be kept in good contact with the head 3.

The sealing means between the individual pieces of the rotary drum 1a according to the embodiment is not limited to the one shown in the figure, and is achieved by, for example, sandwiching a compressible substance between the individual pieces. Method, and in that case, for example, as the groove width becomes narrower, the groove depth can be made shallower.

Of course, the laminated piezoelectric element 6 may use other electromechanical conversion means.

Further, this embodiment is applicable not only for slow motion but also in all cases where the rotation speed of the rotary drum needs to be variable.

[0018]

As is apparent from the above description of the embodiments, according to the magnetic recording / reproducing apparatus of the present invention, the number of rotations of the rotating drum is changed by making the groove width of the rotating drum variable according to the number of rotations. Even if it changes, an optimized air film is created between the rotating drum and the tape, and it is possible to obtain a good recording / reproducing state without tape damage or loss of signal.

[Brief description of drawings]

FIG. 1 is a side sectional view of a guide drum of an embodiment of a magnetic recording / reproducing apparatus of the present invention.

[Fig. 2] Similarly, a front view of the guide drum.

3 is a top view of the rotary drum of FIG.

[Fig. 4] Similarly, the rotating drum 1a when the drum rotation speed is low
And a side view showing the positional relationship of the tape 10 with respect to the fixed drum 2.

[FIG. 5] Similarly, the rotating drum 1a at a high drum rotation speed
And a side view showing the positional relationship of the tape 10 with respect to the fixed drum 2.

FIG. 6 is a front view of a conventional guide drum.

FIG. 7 is a top view of a guide drum in a conventional example.

FIG. 8 is a sectional view of the rotary drum.

[Fig. 9] Similarly, the rotating drum 1a when the drum rotation speed is low
And a side view showing the positional relationship of the tape 10 with respect to the fixed drum 2.

[FIG. 10] Similarly, the rotating drum 1 at a high drum rotation speed
Side view showing the positional relationship of the tape 10 with respect to a and the fixed drum 2.

[Explanation of symbols]

 1a rotating drum 1b, 1c, 1d, 1e individual pieces of rotating drum 1a 1f groove 1g convex portion 2 fixed drum 3 magnetic head 4 rotating drum window 5 variable width groove 6 laminated piezoelectric element 7 laminated piezoelectric element lead wire 8 head base 9 Groove 10 magnetic tape

Claims (1)

[Claims] 1. A guide drum comprising a fixed drum and a rotary drum which is rotatably supported by the fixed drum and which is rotated and fixed to a magnetic head so as to project from a window portion of an outer peripheral surface thereof. The drum is divided into a plurality of pieces, the variable width groove between the plurality of pieces is formed in the circumferential direction of the rotating drum, and has a certain depth fixed or variable by the sealing means, and each piece is A magnetic recording / reproducing apparatus is configured such that the spaces are connected and held by a control element, and the groove width of the variable width groove can be controlled by the control element according to the number of rotations of the rotary drum.