JPS60107722A - Rotary head operating device - Google Patents

Abstract

PURPOSE:To keep a contact pressure of a magnetic head to a tape constant, and to obtain a stable reproducing output voltage by controlling a control current conducting to the first and the second driving coils provided on the rotation center of a rotating body and a fixing part on a concentric circle, and displacing exactly the magnetic head attached to a movable member in the upper and lower directions. CONSTITUTION:Magnetic heads 2, 3 are attached to movable members 4, 5 which can move up and down, respectively, and can be moved and displaced in the upper and lower directions, namely, in the direction of an arrow indicated with a dotted line and a full line. The first and the second driving coils 8a, 8b are wound to a cylindrical stator 9 for constituting a rotary head operating device. This device is constituted so that the magnetized surface of the first and the second magnets 6a, 7a and 6b, 7b fixed to the first and the second movable members 4, 5 is opposed by holding a prescribed air-gap to the first and the second driving coils 8a, 8b wound to the stator 9. A signal to the magnetic heads 2, 3 is sent and received satisfactorily by a rotor 15a and a stator 15b of a rotary transformer.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a helical scan type video tape in which a rotating magnetic head is vertically displaced in order to effectively track signal tracks recorded on a magnetic tape. The present invention relates to a rotary head actuator useful for use in recorders.

Conventional Structure and Problems Conventionally, as a method for displacing a rotating magnetic head as described above, for example, a magnetic henodra is mounted on a rectangular bimorph-type pressure element, and the electro-mechanical conversion characteristics of the piezoelectric element are used. There is a method in which the position of the magnetic head is changed using the following. Due to the nature of its ladle, the bimorph type Uf and electric elements that make up this type of rotary head actuator have hysteresis, are not mechanically strong enough, and are at risk of being destroyed if a large amplitude displacement is attempted. Moreover, the characteristics change over time, making it difficult to construct a durable and stable rotary head actuating device. Moreover, in this method, after transmitting the electric signal containing the position change information from the fixed part to the rotating part, the piezoelectric element must be fully driven by the electric signal shown in 2, so the signal from the fixed part to the rotating part is transmitted. A conductive slip ring and a brush are required for the transmission of the current, resulting in a complicated structure (rC).

Furthermore, in order to adjust the required pitch displacement of the piezoelectric element, i
This method usually requires a voltage of several tens of volts, requires the provision of a high voltage generation circuit for driving the piezoelectric element, and has the disadvantage that the system becomes expensive.

OBJECTS OF THE INVENTION The present invention eliminates the above-mentioned drawbacks of the prior art, and provides a highly efficient rotating head device that is durable, stable in operation, and does not require slip rings or blanks. With the goal.

Structure of the Invention In order to achieve the above object, an uninvented rotary head actuating device includes a first rotary head actuator supported on a rotary body so as to be able to move up and down.
and a second magnetic head; first and second movable parts in which first and second magnets are disposed; The stator is provided with a stator wound with first and second drive coils that face each other while maintaining a predetermined gap with respect to the valley N magnetic surfaces of the first and second Magui throats, 2
Control current in the drive coil? By controlling 1
) The height of the magnetic head is made to match the height of the recording track of the magnetic tape by operating the first and second magnetic heads in the vertical direction.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a top view of a rotary cylinder in which a rotary actuating device is incorporated according to an embodiment of the present invention.

In FIG. 1, 1 is an ordinary rotating drum around which a magnetic tape is wound (rolled), and is a rotating body that is rotated about the rotation axis A2 by a motor (not shown). 2 and 3 are magnetic heads. These are each attached to a vertically movable movable member 4.6, and are movable in the vertical direction, that is, in the direction of the arrow shown by the dotted line and the solid line.

Magnets 6a, 6b, 7a, and 7b are fixed to the separately mentioned movable members 4 and 5, and are magnetized so that the direction of magnetization is radial with respect to the rotation axis A.

10 is a fixed part of the rotating cylinder, and a part is fixed drum 10
It constitutes a.

Reference numeral 9 denotes a cylindrical 1^j constantor constituting a rotary head actuating device, around which first and second drive coils sa and ab are wound. The stator 9 is fixed to the fixed part 1o at a position concentric with the rotation axis A.

11.12 is a ring-shaped leaf spring, and the movable members 4,
5 is fixed to the rotating body 1 via leaf springs 11 and 12, and is supported only in the vertical direction. Further, first and second magnets 6a, 7a and 6b, 7 are fixed to the first and second movable members 4°5 by leaf springs 11 and 12.
The shield magnetic surfaces of the first and second drive coils 8a are wound around the stator 9.

It is configured to face 8b with a predetermined gap therebetween.

Reference numeral 13 denotes a rotating shaft, which is supported by bearings 14a and 14b provided at the boss portion of the fixed portion 10.

15a and 1sb are a rotor and a stator of a rotary transformer, respectively, and signals can be sent and received to and from the magnetic heads 2 and 3 in a good manner. In addition, the connection line from the magnetic heme) 2.3 to the rotary transformer rotor 16a and the lead wire from the rotary transformer stator 16b, and further I: I
i-177 drive coil 8a.

A lead wire for supplying control current to 8b is not shown.

FIG. 2 is a top half view of the embodiment of the present invention shown in FIG. 1 (however, the rotating body 1 is omitted).

FIG. 3 is an exploded perspective view of the embodiment of the invention shown in FIGS. 1 and 2. FIG. Components that are the same as those in FIG. 1 are designated by the same reference numerals, and redundant explanations will be omitted.

In Fig. 3, 21a and 21b are spacers for fixing the leaf springs 11 and 12 to the rotating body 1, and 22a.
, 22b is a spacer 2Ma for fixing 12 leaf springs,
This is a spring fixing screw for fixing to 21b.

Spring fixing spacers 21a, 21b and spring fixing screw 2
2a, 22biCJ: The leaf springs 11 and 12 to which the movable members 4 and 6 are attached are fixed to the rotating body 1.

FIG. 4 is an operational principle diagram for explaining the operation of the embodiment of the present invention shown in FIGS. 1, 2, and 3. In addition,
Components that are the same as those in FIGS. 1, 2, and 3 are given the same reference numerals, and redundant explanations will be omitted. 30 and 31 are drive circuits for supplying control current to the first drive coil 8a and the second drive coil 8b. 32 is an adder;
33 is a subtracter, each of which has a large sword command e1.
e 2 is input.

The operation will be explained below according to FIG.

In FIG. 4, the polarities of the magnetized surfaces facing the first and second drive coils aa and sb of the first magnet) 6a and the second magnet) 6b fixed to the movable member 4 are the same. The first and second drive coils 8a of the first magneto) 7a and the second magneto) 7b are N-pole and fixed to the movable member 6.

The polarity of the magnetized surface facing 8b is N pole.

The operation will be described in the case where the structure is made of Si.

First, when the drive coils sa and sb are energized in the directions shown by the control type Rk solid lines of i4 and 12, respectively, the first magnet 6a fixed to the movable member 4 and the second magnet 6b are In both cases, an upward propulsive force is generated. Each propulsion piece f1. If f2, a propulsive force of f1+f2 acts on the movable member 4, and the movable member 4 moves upward.

(Left below) On the other hand, an upward propulsive force f1 acts on the first magnet 7a fixed to the 'iUJ moving member 6, and a downward propulsive force f2 acts on the second magnet 7b.

Therefore, a propulsive force of fl-f2 acts on the movable member 6. Now, the propulsive force f1 generated in each. Assuming that the magnitudes of f2 are equal and the relational expression f1=f2 holds true,
A propulsive force of 2f1 acts on the movable member 4, and no propulsive force acts on the movable portion 5. As a result, a control current of 1L is passed through each of the first and second drive coils 8a and 8b in the direction shown by the solid line in FIG. 4, and the propulsive force f1. When the magnitudes of f2 are made equal, only the movable member 4 moves upward, and the movable member 5 remains stationary.

Next, the control 7 energizes the first drive coil 8a through the flow 11.
0, only the direction of conduction of the control current 12 to be applied to the second drive coil 8b is changed as shown by the dotted line in FIG. 4 without changing the direction of conduction of the control current 11'.

A case in which each of 12' is energized will be explained.

An upward propulsive force f1' acts on the first magnet 6a fixed to the movable member 4, and the second magnet 1-6b
A downward propulsive force f2' acts on K. I wanted to,
A propulsive force of 11'-12' acts on the movable part A4 (.

On the other hand, a first magnet 7a fixed to the movable member 6,
Both of the second magnets 7bVc are 4fi in the upward direction.
A propulsive force f1'v12' is generated respectively, and a propulsive force of f and '10 f2' acts upward on the movable member 6 as a whole. Now, the magnitude of the propulsive force f1' and f2' generated in each of them is are equal and the relational expression f1'=12' holds true, then no propulsive force acts on the movable part 4, and a propulsive force of 2f1' acts upward on the movable part 5.

As a result, the first and second drive coils 8a.

8b in the direction indicated by the dotted line in FIG.
When ', 12' is energized, the movable member 4 is in a stationary state, and only the movable member 5 moves upward.

In FIG. 4, control current 111 is applied to the first drive coil 8a and the second drive coil 8b at 30 and 31, respectively.
12, 32.33 is the drive circuit for supplying the first
These are an adder and a subtracter for displacing the movable member 4 and the second moving part 6 according to their respective displacement inputs (a 1t (32).

Adder 32. The operation of the subtracter 33 will be explained using mathematical formulas based on FIG.

Movable part AA4. The forces acting on the movable member 5 are respectively Fl
, 1"2, the force F1 acting on the movable member 4 is expressed by the following equation.

F=n”i1++B*S+n++12eBss=n*
B-3(i1+i2) ・−・=−−−(1) However,
N is the number of turns per unit height of the first and second active coils, BI#j, first magnet) 6a.

Magnetic flux density between the magnets 7a and the second magnets 6b and 7b and the stator 9, S is the magneto area where the first and second magnets face the first and second drive coils, respectively]・Opposing area It is.

Similarly, the force acting on the second movable member 6 F211-linear formula % formula % (4.
The following relational expression holds between ゜12 and ゜12.

11-qm(e1+e2) """"'("112=q
m(el-e2) ・・・・・・・・・(4) However,
qrn indicates the conductance of the drive circuit 30.31.

Transforming equations (1) and (2) using equations (■, (4) above, '1 = """ (qm(el 102) +
9m (el-e2) 1=2nBSqrne1...
...(6F2=nBS ig,, (e1+e2)-q
. (el-e2) 1= 2 n B S gme2 °
=-mark-(6).

(0, As is clear from equation (7), the command human power e1 controls the propulsive force F1 of the first movable member 4, and the command human power e2 controls the propulsive force F2 of the second 1liT movable member 5.
each can be controlled independently.

FIG. 6 is a detailed view of the main part for explaining the displacement operation of the magnetic head of the rotary head actuating device of the present invention. In addition, the first
Components that are the same as those in FIG. 2, FIG. 3, and FIG.

In FIG. 5, 40 indicates a magnetic tape.

FIG. 6 (→ shows the situation when no control current is supplied to the first and second drive coils sa and sb. Magnetic head 2
The gap surface is in direct contact with the magnetic tape surface.

FIG. 6 (1=), (C) shows the first and second drive coils 8a.

8b shows how the magnetic head 2 is displaced when control currents 11 and 8b are applied in the directions shown, respectively.

The propulsive force acting on the first magnet 6a, second magnet 6b in FIG. 6 (in the figure) is all downward. Therefore, the combined propulsive force F becomes -upward, and the movable part 4 to which the magnetic head 2 is attached is displaced downward to a position where it is balanced with the restoring force of the leaf springs 11, 12.

Similarly, in FIG. 6(C), the first magneno) 6a
.

The thrust acting on the second magnet () 6b is directed upward, and the magnetic head 2 is displaced upward. Fifth
As is clear from Figure (b) t (C), since the magnetic head 2 is displaced while maintaining a position perpendicular to the tape surface of the magnetic tape 40, the gap of the magnetic head with respect to the tape direction is Good surface contact, and contact pressure is always constant.

As a result, in the rotary head actuating device of the present invention, even if the magnetic head is displaced in the vertical direction, the (Q main output voltage) of the magnetic head does not attenuate. Although the magnetic head 2 has been described, the same applies to the magnetic head 3 attached to the movable member 6.

Effects of the Invention As is clear from the above invention, the rotating head actuating device of the present invention energizes each of the first and second drive coils disposed at a fixed part concentric with the center of rotation of the rotating body. By controlling the control current, the magnetic head attached to the movable member can be reliably displaced in the vertical direction using electromagnetic force. In particular, as in the embodiment of the present invention described above, when an electromagnetic conversion system using a magnet and a drive coil is used as a driving force applying means for a magnetic head, the electrical power is lower than when using a slip ring or brush. It does not generate noise, does not impose an unreasonable load on the rotation of the magnetic head, has a long service life, and is also seen in rotary head actuators that utilize the electro-mechanical conversion characteristics of piezoelectric elements. This is advantageous in that it does not require a special high voltage generation circuit.

In addition, since the rotary head actuating device of the present invention can independently control the amount of vertical displacement of a pair of magnetic heads, each magnetic head can be adjusted to an optimal position with less vibration and lower power consumption. It becomes possible to drive each head independently in a track pattern, and a highly efficient rotary head actuating device can be easily obtained.

Furthermore, by supporting the movable member on which the magnetic head is attached to a rotating body via two leaf springs fixed to its upper and lower end surfaces, the magnetic head is always perpendicular to the magnetic tape surface. Since the contact pressure of the magnetic head to the tape is kept constant, a stable reproduction output voltage can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a rotary head actuating device according to an embodiment of the present invention, FIG. 2 is a plan view of the embodiment shown in FIG. 1, and FIG.
The figure is an exploded perspective view of the same embodiment, FIG. 4 is an operation principle diagram for explaining the operation of the same embodiment, and FIG.
t (C) is a sectional view of a main part in each state of the same embodiment. 1... Rotating body, 2, 3... Magnetic head, 4, 6... Moving part side, 6a, 6b, 7a, 7
b... Magnet, sa, ab... Drive coil, 9... Stator, 11, 12...
・Temporary spring. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 8 Figure 2 Figure 3 Figure 5 <(L) '-b)

Claims (1)

[Scope of Claims] (1) First and second magnetic heads supported by a rotating body so as to be movable up and down, and first and second movable heads on which first and second magnets are disposed. and at least first and second magnets, which are disposed at the rotation center of the rotating body or a fixed part on a concentric circle thereof, and which maintain a predetermined gap with respect to each magnetized surface of the first and second magnets. The stator includes a stator around which a drive coil is wound, and operates the first and second magnetic heads in the vertical direction by supplying a limiting current to the first and second drive coils. A rotary head actuating device characterized by comprising: (2)? Among the first and second movable members in which the JR air head and the first and second magnets are arranged, one movable member faces the first and second drive coils with a predetermined gap therebetween. The movable member is configured such that the polarities of the magnetized surfaces of the first and second magnets are the same, and the other movable member is configured such that the polarities of the magnetized surfaces of the first and second magnets are different from each other. A rotary head actuating device according to claim 1, characterized in that the rotary head actuating device is configured as follows. (3) The first and second movable members are elastic! The magnetized surfaces of the first and second magnets, which are attached to the rotating body through a plate-shaped body and fixed to the movable member, are aligned with the first and second drive coils wound around the stator. The rotary head actuating device according to claim 1 or 2, wherein the rotating head actuating device is configured to face each other with a predetermined gap maintained therebetween. (4) The first and second movable members are two elastic head actuators fixed to the upper and lower end surfaces of the iJ movable members. (6) The rotary head actuating device according to claim (1) or (2), wherein the first and second magnets are respectively magnetized on the same magnetic strip. .