JP2548060Y2 - Driving device for magnetic head - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head driving device.

[0002]

2. Description of the Related Art A video tape recorder (VTR) is a typical example of a magnetic recording / reproducing apparatus which records and reproduces information signals on a magnetic tape by using a rotary magnetic head. It is well known that the current VTR has been greatly improved in image quality and functions due to the dramatic progress from the development to the present. The VTR is currently under development. On the other hand, a VTR that records and reproduces an information signal on a magnetic tape by using a rotating magnetic head is used for recording a television broadcast program or recording a video signal captured by a television camera. It is generally used for recording images, but paying attention to the fact that the magnetic tape in a VTR has a large storage capacity,
TR is, for example, a storage device in a digital information processing device,
Attempts have been made to use the VTR as one of the other components. However, as a component in a digital information processing apparatus, for example, a "computer external auxiliary storage device" or a "computer graphics image" Is sequentially recorded at the end of the calculation, and is used as a moving image by playing it back continuously.
A VTR is used as a component of a digital information processing apparatus because recording of an information signal on a magnetic tape may be performed in a recording mode in which one recording mark ((one track) to several tracks) is used as a unit. In order to achieve this, it is necessary that the information recording operation performed in units of, for example, one track to several tracks be realized with high stability and high reliability as described above. .

[0003] In a VTR in which information signals are recorded and reproduced on a magnetic tape using a rotating magnetic head,
Conventionally, when recording on a specific track on a magnetic tape, or rewriting the recorded content recorded on a specific track on a magnetic tape, for example, running at a predetermined traveling speed is performed. The recording trace of the information signal similar to the recording trace of the information signal recorded and formed on the magnetic tape corresponding to the rotation locus of the rotary magnetic head is intermittently moved by a predetermined distance in the tape running direction and then stopped. Position of the rotating magnetic head generated in correspondence with the absolute position of the rotating magnetic head with respect to the tape reference edge on the magnetic tape so as to be recorded and formed by the rotation locus of the rotating magnetic head with respect to the magnetic tape in the state described above. Drive device for controlling rotation locus of rotating magnetic head during intermittent recording operation based on signal
A VTR equipped with an (actuator) has been proposed. As a driving device for the rotary magnetic head, for example, a driving device using an electro-mechanical conversion element constituted by using an electrostrictive substance as disclosed in Japanese Patent Publication No. 58-18686, A driving device (voice-il motor) using an electro-mechanical electromechanical conversion element as disclosed in 173217 and the like has been proposed.

[0004] In the above-described drive device using an electro-mechanical electromechanical transducer (voice voice motor), displacement can be increased as compared with a drive device using an electromechanical transducer constructed using an electrostrictive substance. No high voltage is required for driving. There are advantages such as easy control. FIG. 4 is a diagram showing an example of the configuration of a drive device using an electro-mechanical conversion element of the electrodynamic type disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 63-173217. In the driving device using the electro-mechanical transducer of the electrodynamic type illustrated in c), H is a magnetic head, 1 and 2 are leaf springs of a non-magnetic material, 3 is a coil bobbin, 4 is a coil, and 5 to 7 are magnetic. Road members, 8 and 9 are permanent magnets, 10 is a pole piece,
The coil bobbin 3 around which the coil 4 is wound is a magnetic path member 6.
In order to be displaceable in the coil axial direction in a magnetic gap formed between the pole piece 10 and the pole piece 10, it is supported by non-magnetic leaf springs 1 and 2 near both ends thereof.

The above-mentioned non-magnetic leaf spring 1 is an annular one in which a supporting portion 1a of a magnetic head H is protruded from a part thereof, and the outer peripheral portion of the annular portion is a magnetic path member 5, 6 is fixed to the magnetic path member by being sandwiched between the magnetic heads H.
Support portion 1a projects outward from the notch portion 11 so that the magnetic head can contact H with the magnetic tape.
The non-magnetic leaf spring 2 is annular,
The outer periphery of the annular portion is fixed to the magnetic path member by being sandwiched between the magnetic path members 6 and 7. The annular non-magnetic leaf spring 2 is provided with a large number of arc-shaped punched portions so as to reduce the mechanical impedance. In the drive device using the electro-mechanical conversion element of the electrodynamic type illustrated in FIG. 4, when an electric current is applied to the coil 4, the electric current flows through the magnetic gap formed between the magnetic path member 6 and the pole piece 10. The coil bobbin 3 is displaced in the direction of the coil axis to displace the magnetic head H.

Meanwhile, in the electromechanical conversion element formed using the electrostrictive material described in the above-mentioned patent publication, the amount of warpage of the electrostrictive material shows a hysteresis characteristic, and the state of warpage of the electrostrictive material is temperature. The trajectory of the displacement of the magnetic head becomes an arc due to the cantilever type, and the contact state between the magnetic head and the magnetic tape becomes poor in the case of a finite length cantilever, etc. There are various problems. Further, in the driving apparatus using the electro-mechanical conversion element of the electrodynamic type described with reference to FIG.
Are supported by the non-magnetic leaf springs 1 and 2 so that the magnetic head H can be displaced in parallel with the coil axis. Is required to be a spring having a complicated shape so as to have a sufficiently low compliance in a narrow portion between the outer periphery of the coil bobbin 3 and the inner periphery of the magnetic path members 5 to 7. However, since the springs 1 and 2 having a complicated shape as described above vibrate in many vibration modes, the coil bobbin has a tendency to move in a direction inclined with respect to the coil axis. For example, as shown in FIG. In this case, the magnetic head H may be tilted by tilting the support portion 1a of the magnetic head H by the angle θ, or a good response is required up to a high frequency by vibrating in many vibration modes. It is difficult to adopt it for the actuator (drive device) used for Further, since the support portion 1a of the magnetic head H is provided by extending a part of the non-magnetic leaf spring 1, the support portion 1a of the magnetic head H is displaced by the coil bobbin 3.
Is excited, and the magnetic head H may vibrate.

[0007] As a magnetic head drive device having no problems in the above-described conventional magnetic head drive device, the present applicant company has previously disclosed in Japanese Utility Model Application No. 3-29925 (FIGS. 6 (a) and 6 (b)). As shown in b), in the hollow part of the hollow yoke 12 having the center hole 13 at the bottom,
The permanent magnet 14 having the center hole and the center pole 15 having the center hole are assembled so that the center holes of the respective components communicate with each other, and the outer peripheral surfaces of both the permanent magnet 14 and the center pole 15 described above. The coil bobbin 17 is driven and displaced in the magnetic gap 16 formed between the coil bobbin 17 and the inner peripheral surface of the hollow portion of the yoke. The support shaft 19 having one end fixed thereto is passed through the center hole of each component part in a loosely fitted state, and the two ends of the support shaft 19 protruding outside the yoke 12 are The magnetic head is supported by individual support members 20 and 21, and is supported by the ends of support shafts projecting outside the yoke 12 from the center hole provided at the bottom of the yoke 12 described above. The magnetic head H is fixed to the tip of the magnetic head holder 22 so that the magnetic head H is provided on the side B opposite to the open end side A of the magnetic path. A magnetic head drive device is proposed in which no magnetic flux is applied to the magnetic head H in a state where the magnetic head H is attached to the magnetic head H.

[0008]

In the proposed magnetic head drive device having the configuration illustrated in FIG. 6, the support member 2 is provided.
Because a simple form is used for 0,21,
In the band used, vibration in an undesired vibration mode did not occur, and the above-described conventional problem could be solved. However, the driving of the already proposed magnetic head shown in FIG. In the apparatus, the coil bobbin 17 and the coil 18 supported by the support shaft 19 and the magnetic head holder 22 are separated by a distance L as shown in FIG.
A component portion composed of the coil bobbin 17 and the coil 18 is disposed between the two support members 20 and 21 disposed at the position 1, and the two support members 2
Since the holder 22 of the magnetic head is fixed to the support shaft 19 in such a manner that the holder 22 of the magnetic head is located in a portion other than between 0 and 21, the magnetic head holder 22 is supported by the support shaft 19 described above. The position of the center of gravity G of the movable portion including the coil bobbin 17, the coil 18, and the magnetic head holder 22 is closer to the support member 21 than the position of 1/2 of the distance L1 between the two support members 20, 21 described above. As shown in FIG. 7B, when the movable portion is subjected to vibration due to disturbance, or when the deformation state of the support member changes due to the vibration mode of the support member, A large inclination angle θα and a displacement Lα may occur in the movable portion, and the displacement state of the movable portion becomes unstable, and a solution has been sought.

[0009]

According to the present invention, a magnetic path member having a center hole in a hollow portion of a hollow yoke having an opening at one end and a center hole at the bottom at the other end is provided. A magnetic circuit in which the center holes of the respective constituent parts communicate with each other and a magnetic gap is formed between the outer peripheral surface of the magnetic path member and the inner peripheral surface of the hollow portion of the yoke. And a support shaft to which one end of a coil bobbin that is driven and displaced in the direction of the center axis of the coil in the magnetic gap is fixed. A means for loosely penetrating into the center hole, and a means for generating a magnetic flux interlinking with the coil wound on the coil bobbin in the magnetic gap portion are further provided. Provided at the bottom of the yoke described above The magnetic head holder is fixed to the end of the yoke that protrudes outside the yoke from the center hole, and the coil bobbin and the magnetic head holder are fixed to the support shaft as described above. At each end, one end of each support member is attached so that the center of gravity of the movable portion is located at the intermediate portion of the support shaft, and the other end of each of the support members is a yoke. And a magnetic head drive device fixed to a fixed portion provided at a position beyond the inner peripheral surface position of the hollow portion.

[0010]

In the hollow yoke having an opening at one end and a center hole at the bottom of the other end, a hollow is provided so as to communicate with the center hole of the yoke. When a current is applied to a coil wound around a coil bobbin located in a magnetic field of a magnetic gap formed between the outer peripheral surface of the magnetic path member and the inner peripheral surface of the hollow portion of the yoke, the support member The coil bobbin fixed to the support shaft supported by the coil is driven and displaced in the direction of the center axis of the coil by the electromagnetic force generated between the current passed through the coil and the magnetic field of the magnetic gap. . The support shaft to which the coil bobbin is fixed is loosely fitted in the center hole of the hollow yoke and the center hole of the magnetic path member. The holder of the magnetic head is fixed to the end of the support shaft that protrudes to the outside, and the movable portion in which the coil bobbin and the magnetic head holder are fixed to the support shaft as described above is a movable part shown in FIG. As illustrated in (a), one end of each of the individual support members 20, 21 is attached to both ends of the movable portion separated by the distance L2, so that the center of gravity G of the movable portion described above is attached. The position is set at a position near the middle between the two support members 20 and 21 described above. Therefore, when vibration due to disturbance is applied to the movable portion or when the deformation state of the support member changes due to the vibration mode of the support member, for example, the same positional displacement as in the case of the conventional device described above with reference to FIG. Even if Lα occurs,
The inclination angle θ in the case of the conventional device shown in FIG.
Only the inclination of the inclination angle θβ as shown in FIG. 8B which is smaller than α is generated, and the state of displacement of the movable portion does not become unstable.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a magnetic head driving device according to the present invention;
FIG. 1 is a longitudinal sectional view of one embodiment of a magnetic head driving device according to the present invention, FIG. 2 is an exploded perspective view of the magnetic head driving device shown in FIG. 1, and FIG. 3 is a magnetic head driving device according to the present invention. FIG. 6 is a partial vertical sectional side view showing a state in which is incorporated in a rotary drum. In FIG. 1 showing a longitudinal sectional view of one embodiment of the magnetic head driving device of the present invention, and FIG. 2 showing an exploded perspective view of FIG. 1, reference numeral 12 denotes a hollow yoke whose one end is open. 1, S is a hollow portion of the yoke 12, and a center hole 13 is formed in the center of the bottom of the other end of the yoke 12. In the hollow part S of the yoke 12, a magnetic path member having a center hole formed therein is fitted with the center hole and the center hole 1 at the bottom of the yoke 12.
3 so that they are in communication with each other.
A magnetic gap 16 is formed between the inner peripheral surface of the second hollow portion S and the outer peripheral surface of the magnetic path member. The magnetic gap 1
6, a yoke 12 and a magnetic path used to form the magnetic gap 16 so that a magnetic field for linking a magnetic flux to a coil 18 movably provided therein is generated. A magnetomotive force portion is provided at an appropriate portion in the magnetic circuit including the members. As the above-mentioned magnetomotive force part,
For example, a permanent magnet may be used, or may be configured as a magnetic path portion excited by an exciting coil.

In the embodiment of the magnetic head driving device shown in FIGS. 1 and 2, the permanent magnet 14 is used as the above-mentioned magnetomotive force portion. Of course, the circuit may be configured as an external magnet type). 1 and 2, a permanent magnet 14 having a center hole 14a is formed in a hollow portion S of the yoke 12 as a magnetic path member having a center hole formed therein.
And a center pole 15 having a center hole 15a formed therein.
Are fixed so that the center holes 14a and 15a and the center hole 13 at the bottom of the yoke 12 communicate with each other, and are used as the magnetic path member and the inner peripheral surface of the hollow portion S of the yoke 12. Permanent magnet 14 and center pole 1
The magnetic gap 16 is formed between the outer circumferential surface of the magnetic head 5 and the like. Center hole 13 of yoke 12
And the center hole 14a of the permanent magnet 14 and the center pole 1
The support shaft 19 of the coil bobbin 17 around which the coil 18 is wound can pass through the center hole 15a of the coil bobbin 17 in a loosely fitted state. After being fitted in the hole formed in the one end 17a, the flange 19b thereof and the one end 17a of the coil bobbin 17 are fixed by means of, for example, bonding. The support shaft 19 to which the coil bobbin 17 is fixed is attached to the center hole 15a of the center pole 15 and the center hole 14a of the permanent magnet 14 as described above.
Through the center hole 13 of the yoke 12.

In the magnetic head driving device shown in FIG. 1, a center hole 1 formed in the bottom of a yoke 12 is provided.
After the fitting hole of the holder 22 of the magnetic head to which the magnetic head H is fixed is fitted to the one end 19 b of the support shaft 19 protruding from the support shaft 19, it is provided near one end of the support member 21. The fitting hole 21b is fitted, and then a screw 40 is screwed into a screw hole provided in the holding body 22 of the magnetic head and a screw hole provided in the support shaft 19, whereby the above-described magnetic head is The holder 22, the support shaft 19, and the support member 21 are fixed. The support member 21 described above is pressed against a protrusion 42 provided on the magnetic head holder 22 by a screw 40 so that the magnetic head holder 2 is pressed.
2 and fixed. The other end of the support member 21 is aligned with the screw holes 38, 39 formed in the protrusion 12b at the bottom of the yoke 12, and the screw holes 36, 37 formed in the support member 21 are aligned. Then, the plate body 31 is placed thereon such that the screw holes 34, 35 thereof match the screw holes 36, 37 formed in the support member 21, and the screws 32, 33 are inserted into the screw holes. Is screwed into the projection 12b at the bottom of the yoke 12, and the other end of the support shaft 19 uses a fitting hole 20b provided near one end of the support member 20 as a screw hole. One end of the support member 20 is fixed to the other end of the support shaft 19 by screwing the set screw 30 into a screw hole provided at the other end of the support shaft 19. The other end of the support member 20 is
After the screw holes 28 and 29 formed in the support member 20 are aligned with the screw holes (not shown) provided in the protrusions 12c at the bottom of the yoke 12, the plate body 23 is placed thereon. 26 and 27 are fitted to the screw holes 28 and 29 drilled in the support member 20 described above,
Screws 24 and 25 are screwed into the screw holes to be fixed to the projections 12c at the bottom of the yoke 12.

A portion 22f to which the magnetic head H is attached and a portion 22b opposite to the above-mentioned portion have substantially the same weight, centering on a position fixed to the support shaft 19 by the screw 40. The movable portion formed by fixing the magnetic head holder 22 and the coil bobbin 17 to the support shaft 19 is, as illustrated in FIG. 8A, at both ends of the movable portion separated by the distance L2. Since one end of each of the support members 20 and 21 is attached to each of the portions, the position of the center of gravity G of the movable portion is the same as that of the above-described 2
The support shaft 19 is positioned between the two support members 20 and 21 at an intermediate position. Therefore, when vibration due to disturbance is applied to the movable portion or when the deformation state of the support member changes due to the vibration mode of the support member, for example, the same positional displacement as in the case of the conventional device described above with reference to FIG. Even if Lα occurs, a smaller inclination angle θβ occurs as shown in FIG. 8B than the inclination angle θα of the conventional device shown in FIG. 7B. Therefore, the state of displacement of the movable part does not become unstable.

FIG. 3 shows a state in which the magnetic head driving device of the present invention constructed as described above is mounted on the rotating drum 44. In FIG. 3, 43 is a lower drum, 44 is an upper drum, 45 is a rotating shaft, 46 and 47 are bearings, and 48 and 49.
Is a rotary transformer, or the magnetic head H attached to the magnetic head drive device of the present invention is located far away from the leakage magnetic flux generating portion of the magnetic circuit in the magnetic head drive device. The magnetic head H attached to the drive device of the above is not adversely affected by the leakage magnetic flux in the magnetic circuit in the drive device of the magnetic head, and the coil bobbin and the magnetic head holder are fixed to the support shaft as described above. Since the position of the center of gravity of the movable portion is located at the intermediate portion of the support shaft 19 between the two support members 20 and 21, the vibration may be applied to the movable portion when disturbance is applied to the movable portion. Even if the deformation state of the support member changes due to the vibration mode, the state of displacement of the movable part does not become unstable.

[0016]

As is apparent from the above description, the magnetic head drive device of the present invention has a hollow having an opening at one end and a center hole at the bottom at the other end. A magnet formed between the outer peripheral surface of the magnetic path member provided in the hollow portion of the yoke in such a manner that the central hole communicates with the central hole of the yoke and the inner peripheral surface of the hollow portion of the yoke. The support shaft to which the coil bobbin located in the magnetic field of the gap is fixed is loosely fitted in the center hole of the hollow yoke and the center hole of the magnetic path member,
The holder of the magnetic head is fixed to the end of the support shaft that protrudes outside the yoke from the center hole provided at the bottom of the yoke, and the coil bobbin and the magnetic head holder are fixed as described above. The movable part fixed to the support shaft is
Since one end of the individual support member is attached to each of the two end portions thereof, the position of the center of gravity of the movable portion is located at the intermediate portion between the two support members. Even when vibration due to disturbance is applied to the movable part or when the deformation state of the support member changes due to the vibration mode of the support member, the state of displacement of the movable part is not made unstable, and the magnetic head of the present invention does not become unstable. In the driving device, all of the problems that have been encountered in the above-described conventional example and the proposed magnetic head driving device can be satisfactorily solved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a magnetic head driving device according to the present invention.

FIG. 2 is an exploded perspective view of the magnetic head driving device shown in FIG.

FIG. 3 is a partial longitudinal side view showing a state where the magnetic head drive device of the present invention is incorporated in a rotary drum.

FIG. 4 is a diagram showing a conventional example of a magnetic head driving device.

FIG. 5 is a diagram for explaining a problem of a conventional magnetic head drive device.

FIG. 6 is a diagram showing a drive device for a magnetic head that has been proposed.

FIG. 7 is a diagram used to explain a problem of a conventional magnetic head drive device.

FIG. 8 is a diagram used for explaining the magnetic head driving device of the present invention.

[Explanation of symbols]

1,2 ... non-magnetic leaf spring, 3,17 ... coil bobbin,
4,18 ... coil, 5-7 ... magnetic path member, 8,9,14 ...
Permanent magnet, 10: pole piece, 15: center pole, 16: magnetic gap portion, 19: support shaft, 20, 21: support member, 22: holder of magnetic head, 14a: center hole of permanent magnet, 15: center Pole, 15a: center hole of center pole, H: magnetic head, S: hollow portion in yoke 12,

Claims (1)

(57) [Scope of request for utility model registration] 1. A hollow yoke having an opening at one end and a center hole at the bottom at the other end,
A magnetic path member having a center hole, in a state in which the center holes of the respective components are communicated with each other, and between the outer peripheral surface of the magnetic path member and the inner peripheral surface of the hollow portion of the yoke described above. One end of a coil bobbin that is driven and displaced in the direction of the center axis of the coil in the magnetic gap is fixedly arranged and fixed so as to constitute a magnetic circuit having a magnetic gap. Means for causing the support shaft to penetrate through the center holes of the respective constituent parts in a loosely fitted state, and for generating a magnetic flux interlinking the coil wound on the coil bobbin in the magnetic gap. Further, a magnetic head holder is fixed to an end of the support shaft, which protrudes to the outside of the yoke from a center hole provided at the bottom of the yoke, and a coil bobbin is further provided as described above. And magnetic head Attaching one end of each of the individual support members to both ends of the movable part having the holding body fixed to the support shaft so that the center of gravity of the movable part is located in the middle of the support shaft, A drive device for a magnetic head, wherein the other end of the support member is fixed to a fixed portion provided at a position beyond the inner peripheral surface position of the hollow portion of the yoke.