JPH02173922A - Magnetic head displacing and driving device - Google Patents

Abstract

PURPOSE:To prevent the inclination of a magnetic head to a magnetic tape and the change of the extent of projection from a rotating drum at the time of displacing the magnetic head by providing connecting members to connect a flexible head supporting member which supports the magnetic head and bimorph elements. CONSTITUTION:A magnetic head 1 is supported by the center part of a flexible head supporting member 2 whose both ends are fixed in the rotating drum, and the center part of the head supporting member 2 and the other ends of plate-shaped bimorph elements 7 and 8 which have one ends supported in a fixed drum like cantilevers are connected by connecting members 11 and 12. Consequently, when bimorph elements 7 and 8 are displaced in the same direction, the magnetic head 1 is displaced on the magnetic tape while being kept parallel with the plane of revolution of the rotating drum. When the head supporting member 2 receives the force due to displacement of bimorph elements, the retrogressing action of bimorph elements is cancelled because supporting arm parts 4a and 4b are made from wide thin plates. Thus, the extent of projection from the rotating drum is not changed when the magnetic head 1 supported by the head supporting member 2 is vertically moved.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is directed to a rotating head type magnetic recording/reproducing device such as a helical scan VTR, in which a magnetic head is displaced in a predetermined direction on a magnetic tape. The present invention relates to a magnetic head displacement drive device for driving the magnetic head in such a manner as to

(Prior Art) In a helical scan VTR, a magnetic tape is wound around a rotating drum to which a magnetic head is attached, and a rotating lower ram is rotated while the magnetic tape is run in one direction, as shown in Fig. 7. Recording is performed as a magnetic pattern at a predetermined angle (approximately 2°34' in the figure) with respect to the longitudinal direction of the magnetic tape. Furthermore, during reproduction, the rotating drum and magnetic tape are similarly rotated and run, so that the magnetic head is scanned along the magnetic pattern formed during recording.

On the other hand, during special playback such as still playback, or special recording in which recording is performed by approximately one rotation of the rotating drum, the magnetic tape is in a stopped state or in a running state other than the normal running state. For this reason, if the magnetic head is simply rotated by a rotating drum as in standard playback, the magnetic head will not be able to accurately follow a predetermined magnetic pattern that forms a certain angle during special playback, and will not be able to accurately follow a predetermined magnetic pattern that forms a certain angle during special playback. It becomes impossible to form a magnetic pattern.

In order to solve such problems during special playback and special recording, it is necessary to move the magnetic head onto the magnetic tape, for example, in the track width direction on the rotation plane of the rotating drum (a plane perpendicular to the rotation axis).
It is sufficient to drive the displacement while keeping the state parallel to . As a magnetic head displacement drive device used for this purpose, as shown in FIG.
A structure in which the magnetic head 83 is supported in a cantilever shape and a magnetic head 83 is attached to the other free end is known.

The bimorph element 81 is made by bonding two approximately rectangular piezoelectric plates with electrodes formed on their surfaces to both sides of a thin metal plate called a shim. The method of bonding the two piezoelectric plates and the wiring are such that, for example, when a positive electrode is applied, the upper piezoelectric plate contracts in the longitudinal direction, and the lower piezoelectric plate extends in the longitudinal direction. This deforms the bimorph element 81 into a concave shape, but since one end is fixed, the free end curves upward and is displaced. Conversely, when a voltage is applied with the polarity reversed, the bimorph element 81 is deformed into a convex shape, and the free end is curved and displaced downward. Therefore, by changing the drive voltage applied to the bimorph element 81, the magnetic head 83 can be driven vertically by an arbitrary amount.

However, in such a configuration, as the amount of displacement of the bimorph element 81 increases, as can be seen from FIG. 8, the magnetic head 83 attached to its free end becomes parallel to the rotation plane of the rotating drum. It will no longer be possible to maintain. Therefore, the magnetic head 83 forms an angle with the magnetic tape 84 compared to when it is at the neutral point shown by the solid line when the drive voltage is 0, and the amount of protrusion from the rotating drum is accordingly reduced. As a result, the contact between the magnetic head 83 and the magnetic tape 84 deteriorates, spacing loss increases, and good recording/reproduction becomes difficult.

On the other hand, as described in Utility Model Application Publication No. 59-180221, for example, two bimorph elements arranged in parallel with a predetermined interval in the thickness direction are supported in a cantilever shape, and the free end is It is known that a connecting piece is provided at the other end of the connecting piece, and a head holder supporting a magnetic head is connected and fixed to the other end of the connecting piece. According to this configuration, the magnetic head supported by the head holder can move while maintaining a state parallel to the rotation plane of the rotating drum in response to the displacement of the bimorph element, so it will not be tilted with respect to the magnetic tape. . However, with this configuration, as the amount of displacement of the bimorph element increases, the position of the free end of the bimorph element retreats from the peripheral surface of the rotating drum toward the fixed end, and the amount of protrusion of the magnetic head from the rotating drum decreases. The problem remains unsolved.

(Problems to be Solved by the Invention) As mentioned in [7] above, in the conventional magnetic head displacement drive device, the magnetic head may tilt with respect to the magnetic tape during displacement, or
There was a problem in that good recording/reproduction was not possible due to the reduction in the amount of protrusion of the magnetic head from the rotating drum.

In view of these points, it is an object of the present invention to provide a magnetic head displacement drive device in which the magnetic head does not tilt with respect to the magnetic tape when the magnetic head is displaced, and the amount of protrusion from the rotating drum does not change. do.

[Structure of the Invention] (Means for Solving the Problems) The magnetic head displacement drive device of the present invention supports a magnetic head at the center of a generally flexible head support member whose both ends are fixed within a rotating drum. At the same time, the central portion of the head support member is connected to one end of each of the plurality of plate-shaped bimorph elements supported in the fixed drum in a 1-1 beam shape by a plurality of connection members. This is what I did.

The number of plate-shaped bimorph elements may be 2n (n is an integer of 2 or more); in that case, the other ends of the 2n bimorph elements are connected to each other by two connecting members, and , the central portion of the head support member is connected.

In addition, the head support member can, for example, withstand the displacement stress of the bimorph element to which the magnetic head is attached (2) the head support member has a substantially inflexible head-receiving portion, and one end of the head-mounting member is connected to the portion. and a pair of support arms having flexibility against the displacement stress of the bimorph element, the other end of which is fixed within the rotating drum.

(Function) When a plurality of bimorph elements are displaced in the same direction, one of the bimorph elements connected to the head support member via one of the connection members pulls the head support member, and the other connection member is forced to the head support member. The other bimorph element connected thereto acts to push up the head support member. Therefore, the magnetic head is displaced over the magnetic tape while remaining parallel to the plane of rotation of the rotating drum.

When the head support member receives a force due to the displacement of the bimorph element, the flexible support part deforms into a gentle S-shape I2 due to the displacement of the bimorph element, and the non-flexible head mounting part deforms accordingly. It is displaced while maintaining its original shape. In this case, the free end of the bimorph element supported in a cantilevered manner tends to retreat from the circumferential surface of the rotating drum. but,
Since both ends of the head support member are fixed to the rotating drum, for example, by forming the support arm portion from a relatively wide thin plate, the effect of the bimorph element attempting to retreat 12 can be counteracted. Therefore, when the magnetic head supported by the head support member moves up and down, the amount of protrusion from the rotating drum hardly changes.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view of a magnetic head displacement drive device according to an embodiment of the present invention, and FIG. 2 is a sectional view showing the magnetic head displacement drive device installed in a rotating drum. In FIGS. 1 and 2, a magnetic head 1 is entirely supported by a head support member 2 having flexibility. The head support member 2 includes a rectangular plate-shaped head mounting portion 3 to which the magnetic head 1 is attached, and a pair of support arm portions 4a and 4b extending from the head mounting portion 3 in a rectangular shape on both sides. ing. Materials for the head support member 2 include, for example, phosphor bronze and beryllium copper, which are known as leaf spring materials, and FRP (FRP) using various fibers and fillers.
Composite materials such as (fiber-reinforced resin) or engineering plastics such as liquid crystal polymers can be used, but in this example, FRP was used. Although the direction in which the FRP fibers are laminated can be arbitrarily determined based on the configuration 31, here, for example, it is assumed to be the longitudinal direction and the width direction of the head support member 2.

The head mounting part 3 of the head support member 2 is formed relatively thick so as to be substantially inflexible against the displacement of the bimorph element, and the support arm parts 4a and 4b are formed so as to be substantially inflexible against the displacement of the bimorph element. It is formed into a thin plate shape so as to have flexibility.

Both ends of the head support member 2, that is, the support arm portions 4a,
At each other end of 4b, the tip of the magnetic head 1 is connected to a rotating drum 33.
The fixing bases 5a and 5b are arranged so as to protrude from the window 34 on the peripheral surface by a prescribed amount, for example, about 60 μm, and come into contact with the magnetic tape 13.
and is fixed to the rotating drum 33 by screws 6a and 6b (6b not shown).

On the other hand, the pair of plate-shaped bimorph elements 7 and 8 are made by laminating two approximately rectangular piezoelectric plates with electrodes formed on the surfaces on both sides of a thin metal plate (shim), as described in the prior art. , are arranged substantially parallel to each other at predetermined intervals in the thickness direction. One end of each of these bimorph elements 7, 8 is
The bimorph elements 7 and 8 are fixedly supported on the rotating drum 33 by a fixing base 9 and screws 10 so that the main surfaces of the bimorph elements 7 and 8 are substantially parallel to the magnetic head mounting surface of the head mounting section 3.

In addition, each other end (free end) of the bimorph element 7.8 is attached to a connecting member 1 on the upper and lower surfaces of the head support member 2.
1.12. Consolidated Department Monthly 11.12
is preferably the same as the head support member 2! -4 (FRP in this case).

FIG. 3 shows a rotary head assembly incorporating the magnetic head displacement drive device of this embodiment. The rotating rod assembly 30 mainly includes a fixed drum 32 having a lead 31 for guiding the magnetic tape 13, and a rotating drum 33 coaxially disposed on the fixed drum 32. The rotating drum 33 has a window 34 through which the tip of the magnetic head 1 protrudes and comes into contact with the magnetic tape 13.

The rotating drum 33 is driven by a motor (not shown) and rotates in the direction of an arrow 35. Further, the magnetic tape 13 is driven by a capstan and a pinch roller (not shown), is guided by a guide post 36, and runs in the direction indicated by an arrow 37, which is opposite to the direction of rotation of the rotary drum 33. As a result, an information signal (for example, a video signal) is recorded on the magnetic tape 13 by the magnetic head 1, and vice versa.
Information signals are reproduced from

Next, the operation of the magnetic head displacement drive device of this embodiment will be explained with reference to FIG. When a driving voltage of a certain polarity is applied to the bimorph elements 7 and 8, the bimorph elements 7 and 8 move in the same direction (upward in this example) as shown by the broken line in FIG.
Displaced to. In this case, the upper bimorph element 7 in the figure pulls up the head mounting section 3 of the head support member 2 via the connecting member 11, and the lower bimorph element 8 pulls up the head mounting section 3 via the connecting member 12. It acts to push down. When a driving voltage of opposite polarity to the above is applied to the bimorph element 7.8, the bimorph element 7.8 is displaced downward in the figure.

In this case, the head is attached to the part 3 of the head support member 2.
The support arm parts 4a and 4b that support the bimorph element 7.8 cancel the force that tends to move the free end of the bimorph element 7.8 from the circumferential surface of the rotating drum 33 toward the fixed end side, and also prevent the head mounting part 3 from rotating. It acts to move while maintaining a state parallel to the rotation plane of the drum 33. That is, the support arm portion 4a,
Since 4b is formed of a relatively wide thin plate, when the bimorph element 7.8 is displaced as described above, the cross section is deformed into a gentle S-shape, and the bimorph element 7.8 is attached to the fixed base. This counteracts the effect of trying to retreat to the 9 side. Therefore, the magnetic head 1 is not tilted (displaced in a predetermined direction) with respect to the magnetic tape 13, and the amount of protrusion of the rotary drum 33 from the window 34 is kept approximately constant.

FIG. 5 shows various configuration examples of the head support member 2. Fifth
In the head support member 2 shown in Figure (a), the head mounting portion 3 is divided into two in the thickness direction, and the support arm portion 4a
, 4b are integrally formed, and the head mounting portion 3 is bonded to sandwich the support arm portions 4a, 4b from both sides. In this case, the head is attached to part 3 and support arm part 4a.

4b may be made of the same material, for example, the head attachment may be made of the same material as part 3.
They may be made of different materials, such as metal, and support arm parts 4a and 4b made of FRP.

In the head support member 2 shown in FIG. 5(b), the head is attached to the connecting member 11 and 11 as explained in FIGS. 1 and 2.
It is integrally formed.

In the head support member 2 shown in FIG. 5(C), the head mounting portion 3 and support arm portions 4a and 4b are integrally formed by press molding using FRP or injection molding using liquid crystal polymer. , although not shown in Figure 17, Figure 5 (
Similarly to 1)), the head support member 2 including the connecting members 11 and 12 may be integrally formed.

The head support member 2 shown in FIG. 5(d) is as shown in FIG. 5(a).
Similarly, the head mounting portion 3 is adhesively fixed to the center portion of the support arms 4a and 4b integrally formed 17. Incidentally, in the head mounting shown in FIG. 5(d), the portion 3 and the support arm portions 4a, 4b may be integrally formed.

Among these, the examples shown in FIGS. 5(b), 5(e), and 5d have the advantage that assembly is simplified and mass production is excellent.

FIG. 6 is a perspective view of a magnetic head displacement drive device according to another embodiment of the present invention, in which four bimorph elements 21, 22 are shown.
, 23.24 is used.

In this case, the connecting members 25, 26 connect the bimorph elements 21, 22 and 23, 24 and the head mounting portion 3 of the head support member 2, respectively, and
It has the role of connecting 1.22 and bimorph elements 23, 24, respectively.

More specifically, each of the connecting portion shrines 25 and 26 has two grooves 27a, 27b and 28a, 28b, and the bimorph element 21 is inserted into these grooves 27a, 27b, 28a, 28b.
, 22, 23, and 24 are inserted, respectively.

According to this embodiment, it is possible to increase the force that contributes to the displacement drive of the magnetic head by the bimorph element.

Note that the number of bimorph elements may be larger, and is generally 2n, and the other ends (free ends) of these 2n bimorph elements are connected to each other by two connecting members, and The head of the head support member 2 can be attached by connecting it to the part 3.

As described above, the magnetic head displacement drive device of the present invention is particularly effective when performing special reproduction such as still reproduction in a helical scan VTR, or special recording in which recording is performed by approximately one rotation of a rotating drum.

FIG. 7 schematically shows a magnetic pattern on a magnetic tape of a helical scan VTR. When recording/reproducing is performed under normal conditions, the magnetic pattern formed by the magnetic head is 7]
, ,72.73.

On the other hand, when the magnetic tape 13 is running or stopped in a state other than the normal state, for example, when the magnetic tape 3 is stopped (still reproduction), the scanning locus of the magnetic head is indicated by an arrow 74. In this case, as can be seen from the figure, the magnetic head starts scanning from the starting part 75 of the magnetic pattern 72, but leaves the magnetic pattern 72 midway, crosses the guard band 76, and moves to the ending part 77 of the adjacent magnetic pattern 71. reach.

With the magnetic head fixed in this manner, not only is it impossible to scan the entire length of the magnetic pattern 72 necessary for still reproduction, but also noise is mixed into the reproduced signal due to the magnetic head passing through the guard band 76. do. In such a case, the magnetic head displacement drive device of the present invention may be used to displace the magnetic head in the direction of the arrow 78 so as to scan along the magnetic pattern 72. Also,
When the magnetic tape 13 runs in a state other than the normal state, for example, when performing 1/2 times slow motion playback or reverse playback, by similarly displacing the magnetic head, playback with less noise is possible. becomes.

[Effects of the Invention] In the magnetic head displacement drive device according to the present invention, the magnetic head does not tilt with respect to the magnetic tape during displacement, and the amount of protrusion from the rotating drum does not change. Therefore, a good contact state between the magnetic head and the magnetic tape can be maintained, and good recording/reproduction is possible without causing spacing loss.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a magnetic head displacement drive device according to an embodiment of the present invention, FIG. 2 is a sectional view showing the magnetic head displacement drive device of the same embodiment installed in a rotating drum, and FIG. The figure is a perspective view of a rotary head assembly in which the magnetic head displacement drive device is incorporated, FIG. 4 is a side view schematically showing the state of the magnetic head displacement drive device of the same embodiment during displacement, and FIG. b), (c), and (d) are perspective views showing various examples of the head support member according to the present invention, FIG. 6 is a perspective view of a magnetic head displacement drive device according to another embodiment of the present invention, and FIG.
This figure is a diagram schematically showing a magnetic pattern on a magnetic tape in a helical scan VTR, and FIG. 8 is a side view showing a schematic configuration of a conventional magnetic head displacement drive device. 1... Magnetic head, 2... Head support member, 3...
・Head mounting section, 4a, 4b...Support arm section, 5
a, 5b... fixed base, 7.8... bimorph element,
9...Fixing base, 11.12...Connecting member, 13...
・Magnetic tape, 30... Rotating head assembly, 3
2... Fixed drum, 33... Rotating drum, 21,2
2゜23.24...bimorph element, 25.26...
・Connection member. Applicant's Representative Patent Attorney Takehiko Suzue

Claims (3)

[Claims] (1) In a magnetic head displacement drive device that drives a magnetic head mounted within a rotating drum to displace it in a predetermined direction on a magnetic tape that is wound around the rotating drum and runs, both ends of the magnetic head are fixed within the rotating drum. , a generally flexible head support member that supports the magnetic head at the center; and a plurality of plates each having one end supported within the rotating drum and arranged substantially parallel to each other at predetermined intervals in the thickness direction. What is claimed is: 1. A magnetic head displacement drive device comprising: a bimorph element; and a plurality of connecting members connecting each other end of the plurality of plate-like bimorph elements to a central portion of the head support member. (2) In a magnetic head displacement drive device that drives a magnetic head mounted within a rotating drum to displace it in a predetermined direction on a magnetic tape that is wound around the rotating drum and runs, both ends of the magnetic head are fixed within the rotating drum. , a generally flexible head support member that supports the magnetic head at the center; and 2n head support members each having one end supported within the rotating drum and arranged substantially parallel to each other at predetermined intervals in the thickness direction. n is an integer of 2 or more), and two plate-shaped bimorph elements, each of which connects the other end of each of the 2n plate-shaped bimorph elements to each other and to the central portion of the head support member. 1. A magnetic head displacement drive device comprising: a connecting member; (3) The head support member has a magnetic head attached to it.
a head attachment portion substantially inflexible with respect to displacement of the bimorph element; one end coupled to the head attachment portion;
3. The magnetic head displacement drive device according to claim 1, further comprising a pair of support arms having the other end fixed within the rotating drum and having flexibility with respect to displacement of the bimorph element. .