JPH0132172Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a magnetic head device used in an automatic tracking device of a video tape recorder, etc., and particularly relates to a magnetic head device that improves the contact state between the tip of the head chip and the magnetic tape. It is related to the device.

<Background technology and its problems> In a general rotary head type video tape recorder, when the tape speed is different from that during recording, such as during slow, still, quick, and reverse playback, the tracking locus of the magnetic head changes from the magnetic tape. Off the one video track above,
So-called guard band noise occurs. In order to remove such guard band noise, automatic tracking control is known in which the magnetic head itself is displaced in the track width direction and scans over one video track during one tracking. There is.

An example of a rotating magnetic head device for a video tape recorder that enables such automatic tracking control is shown in FIG.

In FIG. 1, a rotating magnetic head device 1
has a rotating upper drum 2 and a fixed lower drum 3. The rotational drive shaft 4 connects the upper drum 2 and the motor 5, and the upper drum 2 is rotated by the motor 5 in the direction of arrow A in the figure at a rotational speed of 3600 rpm. The magnetic tape 6 is wound diagonally around the upper drum 2 and the fixed lower drum 3 at a winding angle of approximately 360 degrees, and is driven to run in the direction of arrow B in the figure.
A pair of guide poles 7 and 8 are provided to regulate the winding angle of the tape, and a tape guide stepped portion 9 is provided on the lower drum 3. Furthermore, the magnetic head device 10 basically has one magnetic head, and its head chip 1
1 is placed on a movable element such as a bimorph plate so as to slightly protrude from the outer peripheral surfaces 2a, 3a of each drum 2, 3. And this head tip 1
Video tape signals are recorded and reproduced by the tip of the magnetic tape 1 slidingly coming into contact with the magnetic tape 6.

When a video signal is recorded on the magnetic tape 6 using such a rotating magnetic head device 1, recording tracks T are sequentially formed obliquely as schematically shown in FIG. When reproducing the recorded magnetic tape 6 in a normal state, the magnetic tape 6 is driven to run in the direction of arrow B in the figure, and the head chip 11 scans over the recording track T in the direction of arrow C in the figure.

On the other hand, when the running speed of the magnetic tape 6 is different from that during recording, such as when playing back a still image called still playback, the head chip 11 moves as shown by the broken line in the figure unless some measure is taken. The head chip ₁₁ is displaced by the movable element, and the scanning trajectory is recorded. So-called automatic tracking control is performed to follow the track T.

As an example of the configuration of a magnetic head device for performing such tracking control, the one shown in FIGS. 3 and 4 is known, for example. 3 and 4, the head chip 11 is attached to the electro-mechanical transducer, for example, the tip 12f of the bimorph plate 12, and the base end 12r of the bimorph plate 12 is attached to the head base 1.
By attaching the bimorph plate 12 to the platform protrusion 14 of No. 3 and fixedly supporting it to the upper drum 2 through the screw attachment hole 15, the head chip 11 can be bent in response to an electric signal. Middle arrow D
A device that can be freely displaced in any direction is known. Note that the direction of the arrow D is the head chip 11.
is the same as the gap direction of Further, 16 is a lead wire of the head chip 11, and 17 and 18 are lead wires of the bimorph plate 12.

The bimorph plate 12 is made of two plates 12a and 12b made of lead zirconate titanate (PbZrO ₃ -PbTiO ₃ ), which is a piezoelectric material, so that their polarization directions are opposite to each other, for example, in the direction of arrow P in FIG. As shown, it is constructed by bonding together a 12 m central reinforcing metal plate that serves as an intermediate electrode, and electrostrictive drive electrodes 12 are provided on both surfaces.
c, 12d are formed. When a voltage is applied between these two outer electrodes, this bimorph plate 12
has a constant radius of curvature from the fixed end to the head base 13 to the fixed end to the head chip 11 to the displacement end of the tip to which the head chip 11 is attached, as shown by the imaginary line in the schematic diagram of FIG. It is uniformly curved and displaced. Note that the direction and amount of displacement of the head chip 11 are determined by the direction (polarity) of voltage application and the applied voltage.

By the way, as the bimorph plate 12 bends, as is clear from FIG.
The tip 12f of the gap is oriented in a warped direction, and is not in perpendicular contact with the magnetic tape 6, resulting in an error in the angle of contact with the magnetic tape 6, and the gap surface is pulled back in a direction away from the magnetic tape 6. As a result, the contact pressure against the magnetic tape 6 decreases. As a result, the contact with the magnetic tape 6 becomes poor and the reproduced output voltage of the head is attenuated.

Conventionally, as shown in FIG. 5, a head bolt 19 made of carbon fiber or the like is fixedly supported at the tips of two bimorph plates 12, 12, and the head chip 11 is supported by this holder 19. , the head chip 11 is moved in parallel in the direction of arrow D in the figure to avoid occurrence of an error in the angle of contact with the magnetic tape 6.

However, as is clear from FIG. 5, as the bimorph plates 12, 12 are curved,
Since the amount of protrusion of the head chip 11 relative to the magnetic tape 6 is reduced, the contact pressure of the head gap against the magnetic tape 6 is reduced. As a result, the head gap has poor contact with the magnetic tape 6, resulting in attenuation of the reproduction output voltage of the head.

<Purpose of the invention> The present invention was made in view of the above-mentioned circumstances, and by improving the head holder, changes in the amount of protrusion of the head tip caused by the curvature of the bimorph plate can be reduced, thereby making it possible to improve this type of magnetic head. The purpose is to improve the performance of the device.

<Means for Solving the Problems> The present invention was proposed in order to solve the problems of the above-mentioned conventional techniques. at least two electro-mechanical transducers each comprising a piezoelectric element having an electrode adhered to its surface so as to curve and deform in the same direction in accordance with the above-mentioned electro-mechanical transducer, and one end supported by each of the electro-mechanical transducers,
It is bent into a substantially crank shape through a bending part formed in the middle, and the other end is located on the extension line of the center line of each of the electro-mechanical transducers in the inactive state, and has flexibility. and a head support member to which the other end of each of the connection members is connected and fixed, and a head chip is fixedly supported.

<Embodiments> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. 6 and 7.

In this embodiment, as shown in FIG. 5, the present invention is applied to a magnetic head device using two bimorph plates 12, 12, and for convenience of explanation, the above-mentioned members are The same members are given the same reference numerals and their explanations will be omitted.

The two bimorph plates 12, 12 are arranged parallel to each other so that their base ends are connected to the head base 20.
These bimorph plates 12, 12 are fixedly supported by
A spacer 21 is arranged in between.

Furthermore, the electrical connections between the respective electrodes of these bimorph plates 12, 12,
12, all of them are displaced in the same direction and by the same amount of displacement.

On the other hand, a head chip holder 23 is attached to the tip of each of the bimorph plates 12, 12.

This head chip holder 23 is composed of a head chip base 24 which is a head support member to which the head chip 11 is attached, and connecting members 25 and 26 that connect this head chip base 24 and the tips of each bimorph plate 12 and 12. ing.

The connecting members 25, 26 are bent into a substantially crank shape through two bent portions 27, 28, 29, 30, and one end is connected to the electrode 12d on the lower surface of the distal end side of each of the bimorph plates 12, 12. , 12d. The other ends of the connecting members 25 and 26 are connected to each of the bimorph plates 12 and 1 shown by the dashed line in FIG.
2, are positioned on the center lines l ₂ and l ₃ of 2. The other ends of the connecting members 25, 26 are connected by a head chip base 24, and the connecting members 25, 26 and the head chip base 24 constitute the head chip holder 23 as described above.

In this embodiment, the head chip holder 23 is made of an insulating material such as plastic, and the connecting members 25 and 26 are made somewhat thin, and the head chip base 23 is made of an insulating material such as plastic.
4 is made thick and made of a rigid member so as not to be easily deformed even when a load is applied to both ends.

Therefore, as mentioned above, the head tip holder 2
Even if the connecting members 25 and 26 constituting the connecting members 3 are fixed to the electrodes 12d and 12d surfaces of the bimorph plates 21 and 21 through the respective attachment parts 31 and 32, the distance between the connecting members 25 and 26 is In addition to being insulated, the head chip base 24 can always maintain a position parallel to the magnetic tape 6 when the bimorph plates 12, 12 are bent.

Note that the head tip holder 23 is not limited to being made of the above-mentioned materials, but may be made of any material that can insulate between the connecting members 25 and 26 and has flexibility, such as the above-mentioned material. The head chip base 24 may be made of light and strong carbon fiber or the like, and a thin elastic steel plate or the like may be embedded in the head chip base 24.

When a bimorph drive signal is supplied to each electrode of each bimorph plate 12, 12 constituting the magnetic head device having the above-mentioned configuration, each bimorph plate 12,
12 curves and deforms as shown by the dashed line in FIG. 7 depending on the signal level.

When the bimorph plates 12, 12 are bent, the connecting members 25, 26 are connected by the head chip base 24, so that the head chip base 24 is connected to the magnetic tape 6.
move approximately parallel to.

Therefore, according to this magnetic head device, by such parallel movement of the head chip base 24,
Even if the bimorph plates 12, 12 are bent and deformed,
The error in the contact angle of the head gap provided in the head chip 11 with respect to the magnetic tape 6 can be extremely reduced.

Further, according to the magnetic head device according to this embodiment, the connecting members 25 and 26, which are bent into the substantially crank shape as the bimorph plates 12 and 12 are bent, have bent portions 27 and 28. , 29, 30
Since the head chip 11 is bent and deformed at , the amount of change in the amount of protrusion of the head chip 11 can be reduced compared to the conventional magnetic head device shown by the two-dot chain line in FIG. Therefore, even if the amount of change in the bimorph plates 12, 12 increases to some extent, good reproduction signal characteristics can be obtained without causing a large change in the contact pressure between the head gap and the magnetic tape 6.

Although the above embodiment shows a magnetic head device using two bimorph plates 12, 12, the magnetic head device according to the present invention may use even more bimorph plates. .

<Effects of the Invention> According to the present invention, it is possible to reduce the amount of protrusion of the head gap caused by the curved deformation of the bimorph plate, and also to reduce the error in the angle of contact with the magnetic tape.

Therefore, it is an object of the present invention to provide a magnetic head device that can obtain good recording and reproducing characteristics without causing attenuation of the reproducing output voltage of the head due to deterioration of the contact state of the head gap with the magnetic tape, as in conventional magnetic head devices. be able to.

[Brief explanation of the drawing]

Fig. 1 is an external perspective view schematically showing an example of a rotating magnetic head device, Fig. 2 is a plan view schematically showing a recording track on a magnetic tape, and Fig. 3 is a specific example of a conventional magnetic head device. 4th enlarged perspective view showing
The figure is also a schematic side view. FIG. 5 is a schematic side view showing an example of the prior art of the present invention. FIG. 6 is a side view schematically showing an embodiment of the present invention, and FIG. 7 is a schematic side view showing the operating state of the embodiment shown in FIG. 11... Head chip, 12, 12... Bimorph board, 23... Head chip holder, 24...
Head tip base, 25, 26...connecting member.

Claims (1)

[Claims for Utility Model Registration] At least one piezoelectric element, the ends of which are supported on a base so as to be parallel to each other, and each of which has electrodes adhered to its surface so as to be curved and deformed in the same direction in response to a drive signal. Two electro-mechanical transducers, one end supported by each of the electro-mechanical transducers, bent into a substantially crank shape through a bending part formed in the middle, and the other end being free. A plurality of flexible connecting members are located on an extension of the center line of each of the electro-mechanical transducers in an operating state, and the other end of each of the connecting members is connected and fixed, and a head chip is provided. 1. A magnetic head device comprising a head support member that is fixedly supported.