JP2601088B2 - Rotating head device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary head device such as a video tape recorder and a digital audio tape recorder.

[0002]

2. Description of the Related Art FIG.
FIG. 4 is a cross-sectional view showing a conventional rotary head device disclosed in Japanese Patent Application Publication No. 4 (JP-A) No. 4-44. In FIG. 4, reference numeral 1 denotes a cylindrical fixed drum, and a lead for guiding a magnetic tape (not shown) is provided on the outer peripheral surface.

Reference numeral 2 denotes a fixed shaft mounted at the center of the fixed drum 1, 2a and 2b denote radial dynamic pressure bearing grooves provided on the fixed shaft 2, and 3 denotes a rotating drum having the same cylindrical shape as the fixed drum 1. The rotary drum 3 has a fixed shaft 2
And a peripheral portion 3b to which the central portion 3a is attached by press fitting or the like. Reference numeral 4 denotes a magnetic head for recording a signal on a magnetic tape or reproducing a signal recorded on the magnetic tape.

[0004] Reference numeral 5 denotes a head base attached to the rotating drum 3.
Is mounted so as to protrude from the outer peripheral surface by a predetermined amount. Reference numeral 6 denotes a motor, which comprises a stator 6a attached to the fixed drum 1 and a rotor 6b attached to the rotating drum 3. Reference numeral 7 denotes a rotary transformer, which includes a stator 7 a attached to the fixed drum 1 and a rotor 7 b attached to the rotating drum 3. Reference numeral 8 denotes a thrust bearing, and 9 denotes a thrust bearing plate attached to the center portion 3a of the rotating drum 3.

FIG. 5 is a perspective view showing a main part of a conventional magnetic recording / reproducing apparatus. In FIG. 5, reference numeral 61 denotes a deck base to which the rotary head device 51 having the configuration shown in FIG. 8 is attached at a predetermined angle. Reference numeral 62 denotes an entrance tape guide roller, which is provided with a flange 62a for regulating the vertical position (position in the width direction) of the magnetic tape T wound around the rotary head device 51.

Reference numeral 63 denotes an entrance inclination guide for inclining the magnetic tape T wound around the rotary head device 51. Reference numeral 64 denotes an outlet inclination guide, and the rotary head device 5
This is to return the magnetic tape T peeled off from No. 1 to its original state. An exit tape guide roller 65 is provided with a flange 65a for regulating the upper and lower positions (positions in the width direction) of the magnetic tape T peeled off from the rotary head device 51. C indicates a tape cassette that stores the magnetic tape T.

Next, the operation will be described. First, FIG.
When the magnetic tape T is wound around the rotary head device 51 and run as shown in FIG. 3 and the rotary drum 3 and the magnetic head 4 are rotated by operating the motor 6, signals are recorded on the magnetic tape T by the magnetic head 4. The signals recorded on the magnetic tape T can be reproduced by the magnetic head 4. Transmission of a signal from the magnetic head 4 to a fixed side such as an electric circuit or a signal from the fixed side to the magnetic head 4 is performed through the rotary transformer 7 in a non-contact state.

[0008]

Since the conventional rotary head device is configured as described above, the magnetic head 4 is fixed to the rotary drum 3 and cannot move in the axial direction of the fixed shaft 2. Therefore, when a signal is reproduced from the magnetic tape T on which the track has been bent due to a running adjustment defect of the tape path or the like, the track cannot be accurately traced by the magnetic head 4 and the output of the reproduced signal is reduced. was there.

Further, since the fixed drum 1 and the rotating drum 3 are cylindrical, when recording tracks on the magnetic tape T with the tracks inclined, the fixed drum 1 and the rotating drum 3 are inclined as shown in FIG. The use of the entrance inclined guide 63 and the exit inclined guide 64 for the tape path has disadvantages in that the tape path is complicated and the height of the deck is increased.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned disadvantages, and it is possible to obtain a reproduction signal of an appropriate output even if a track is bent on a magnetic tape. It is an object of the present invention to provide a rotary head device capable of simplifying a tape path to reduce the height of a deck and setting a position of a magnetic head to a predetermined height or a reference height.

[0011]

According to a first aspect of the present invention, there is provided a rotary head device including a permanent magnet for generating a fixed magnetic field and a rotating head provided with the magnetic head and disposed between magnetic poles of the fixed magnetic field. A magnetic bearing comprising a magnetic pole, and a coil for changing the strength of the fixed magnetic field by flowing a control current to move the magnetic head up and down in the axial direction of the rotating shaft are provided.

Further, in the rotary head device according to the second invention, the outer peripheral surfaces of both fixed drums are made elliptical, and the rotating shaft is inclined with respect to the center axis of both fixed drums.
A permanent magnet for generating a fixed magnetic field, the magnetic head is mounted, a magnetic bearing composed of rotating magnetic poles disposed between the magnetic poles of the fixed magnetic field, and the strength of the fixed magnetic field by flowing a control current. And a coil for moving the magnetic head up and down in the axial direction of the rotating shaft by changing the magnetic head.

Further, the rotary head device according to the third invention further comprises a displacement sensor for detecting a displacement of the magnetic head, and a driver for controlling a current to the coil based on a detection output of the displacement sensor. It is.

[0014]

The magnetic head of the rotary head device according to the present invention moves in the axial direction of the rotary shaft by an electromagnetic force generated by applying a current to the coil. Further, the driver controls a current supplied to the coil based on a detection output of the displacement sensor.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a configuration of a rotary head device according to a first embodiment of the present invention. The same or corresponding parts as those in FIG. In FIG. 1, reference numeral 11 denotes a rotating shaft, 11a and 11b denote radial dynamic pressure bearing grooves provided on the rotating shaft 11, and the rotating shaft 11 is rotatably supported by the fixed drum 1.

Reference numeral 21 denotes an annular mounting table attached to the fixed drum 1, and reference numeral 22 denotes a first fixed magnetic pole made of an annular magnetic material having an inner peripheral portion of the lower surface attached to the mounting table 21. The fixed magnetic pole 22 is mounted concentrically with respect to the rotating shaft 11, has a substantially U-shaped vertical cross section, an open portion thereof is directed outward, and a coil 16 is wound around a concave portion.

On the inner peripheral side of the upper surface of the first fixed magnetic pole 22, a permanent magnet 13A magnetized in the thrust direction is mounted concentrically with respect to the rotating shaft 11. Reference numeral 23 denotes a second fixed magnetic pole made of a substantially flat and annular magnetic material, which is concentric with the rotating shaft 11 and whose inner peripheral side on the lower surface is attached to the permanent magnet 13A. The outer peripheral sides of the first fixed magnetic pole 22 and the second fixed magnetic pole 23 face each other with a predetermined gap.

Numeral 24 denotes a rotating magnetic pole made of an annular magnetic material attached to the inner surface of the rotating drum 3 and has a substantially L-shaped vertical cross section, and the short piece portion has a first fixed magnetic pole 22 and a second fixed magnetic pole. It is located with a predetermined gap in the gap formed by the magnetic pole 23. The permanent magnet 13A, the coil 16, the first and second fixed magnetic poles 22, 23, and the rotating magnetic pole 24 constitute a magnetic bearing (thrust magnetic bearing).

Next, the operation will be described. First, the magnetic flux F ₂ is generated in the direction indicated by the arrow in the magnetic path formed by the first fixed magnetic pole 22, the second fixed magnetic pole 23, and the rotating magnetic pole 24 by the permanent magnet 13 </ b> A. When a magnetic flux F ₃ is generated in a direction indicated by an arrow in a magnetic path formed by the first fixed magnetic pole 22 and the rotating magnetic pole 24, the magnetic flux F in the gap between the first fixed magnetic pole 22 and the rotating magnetic pole 24 is increased.
₂ and F ₃ are in the same direction, and the first fixed magnetic pole 22
Since the attractive force between the rotating magnetic pole 24 and the rotating magnetic pole 24 increases, the rotating magnetic pole 24 and the rotating drum 3 move downward.

The first fixed magnetic pole 22 and the rotating magnetic pole 2 are changed by changing the direction of the current flowing through the coil 16.
When the magnetic flux F ₃ is generated in the direction opposite to the direction indicated by the arrow in the magnetic path formed by the magnetic path 4, the directions of the magnetic fluxes F ₂ and F ₃ in the gap between the first fixed magnetic pole 22 and the rotating magnetic pole 24 become different. Since the attractive force between the fixed magnetic pole 23 and the rotating magnetic pole 24 becomes large, the rotating magnetic pole 24 and the rotating drum 3 move upward. Accordingly, by appropriately selecting the weight of the rotating member including the rotating shaft 11, the rotor 7b of the rotary transformer 7, the rotating drum 3, and the rotating magnetic pole 24 and the magnetic force of the permanent magnet 13A, the rotating magnetic pole 24 is fixed to the first fixed position. It can float between the magnetic pole 22 and the second fixed magnetic pole 23.

As described above, according to this embodiment, the magnetic head 4 is moved by an arbitrary amount in the axial direction of the rotating shaft 11 by controlling the direction and magnitude of the current flowing through the coil 16. By controlling the current supplied to the coil 16 by appropriate control means, an appropriate reproduction signal can be obtained even if the magnetic tape T has a curved track. Further, since the respective parts are arranged concentrically about the rotation shaft 11, the members for moving the magnetic head 4 can be reduced in size, a small-diameter rotation head device can be obtained, and the rotation load can be reduced. Can be done.

FIG. 2 shows the structure of a rotary head device according to a second embodiment of the present invention, wherein FIG. 2 (a) is a plan view and FIG. 2 (b) is a cross-sectional view, which is the same as FIGS. Or, the same reference numerals are given to the corresponding parts, and the description is omitted. In FIG.
Reference numeral 12A denotes an upper fixed drum, and as shown in FIG. 2A, the outer peripheral shape together with the lower fixed drum 1 is elliptical. The fixed drum 1 is provided with a lead for guiding the magnetic tape T horizontally in a vertical state, and the stator 6a of the motor 6 is fixed to the fixed drum 12A.

The rotating shaft 11 is inclined at a predetermined angle with respect to the centers of the fixed drums 1 and 12A so that the magnetic head 4 draws a circular locus and projects a predetermined amount from the outer peripheral surface of the fixed drums 1 and 12A. It is. And 25 is the rotating shaft 11
The rotating magnetic pole 24 is attached to a rising outer peripheral edge.

Next, an operation different from that of the first embodiment shown in FIG. 1 will be described. When the rotary shaft 11 is rotated by the motor 6 in a state where the rotary head device is installed in a vertical state, the first yoke 12a and the like rotate, so that the magnetic head 4 rotates with a circular locus, and A signal is recorded on the magnetic tape T in a proper track.

As described above, according to this embodiment, in addition to the effects obtained in the embodiment of FIG. 1, there is no need to tilt the rotary head device, so that the tape path can be simplified. Further, since there is no need to tilt the rotary head device, the height of the rotary head device is reduced, and the height of the deck can be reduced.

In the third embodiment, as shown in FIGS. 1 and 2, the displacement sensor 31 is mounted on the fixed drum 1 and outputs a voltage (V _s ) corresponding to the displacement of the magnetic head 4. is there.

FIG. 3 is a block diagram showing a magnetic head position control circuit of the rotary head device. 3, reference numeral 52 denotes a sensor amplifier, which amplifies the voltage (V _s ) detected by the displacement sensor 31. Reference numeral 53 denotes a reference voltage generator that outputs a voltage (V _s ) output from the displacement sensor 31 when the magnetic head 4 is at a reference position (height) as a reference voltage (V _ref ).

Numeral 54 denotes a subtractor, and a reference voltage generator 53
Outputs a voltage (V _OP ) obtained by subtracting the voltage (V _s ) output by the sensor amplifier 52 from the reference voltage (V _ref ) output by the sensor. Numeral 55 denotes a driver for controlling the current supplied to the coil 16 so that the voltage (V _OP ) output from the subtractor 54 becomes zero, thereby moving the position of the magnetic head 4.

Next, the operation will be described. First, when the displacement sensor 31 detects the displacement of the magnetic head 4 and outputs a voltage (V _s ) corresponding to the displacement, the voltage (V _s ) is amplified by the sensor amplifier 52 and is applied to the reference voltage generator 53. The voltage is subtracted from the voltage (V _ref ) by the subtractor 54. Therefore, the driver 55 outputs the voltage (V _OP ) from the subtractor 54.
Is supplied to the coil 16 so that
The height of the magnetic head 4 is set to a predetermined height or a reference height corresponding to the reference voltage (V _ref ) of the reference voltage generator 53.

As described above, according to this embodiment, the height of the magnetic head 4 can be easily set to a predetermined height reference height.

[0031]

According to the present invention, the following effects can be obtained. First, since the magnetic head is moved in the axial direction of the rotation axis by the current flowing through the coil, the magnetic head can be moved and traced accurately even for track bending, and an appropriate reproduction signal can be obtained. Also, since each member is arranged concentrically with the rotation axis, each member for moving the magnetic head can be reduced in size,
It is possible to provide a small-diameter rotary head device and reduce the rotational load. In addition, since both fixed drums are elliptical and the rotation axis is inclined, the rotary head device can be installed vertically with respect to the tape path, so that the tape path is simplified and the height of the deck is reduced. Can be. And since the displacement sensor was provided,
Since the height of the magnetic head can be set to a predetermined height or a reference height, incompatibility due to variations between devices can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a configuration of a rotary head device according to a first embodiment of the present invention.

FIGS. 2A and 2B show a configuration of a rotary head device according to a second embodiment of the present invention, wherein FIG. 2A is a plan view and FIG.

FIG. 3 is a block diagram showing a magnetic head position control circuit of the rotary head device.

FIG. 4 is a sectional view showing a conventional rotary head device.

FIG. 5 is a perspective view showing a main part of a conventional magnetic recording / reproducing apparatus.

[Explanation of symbols]

 Reference Signs List 1 fixed drum 3 rotating drum 4 magnetic head 6 motor 7 rotary transformer 11 rotating shaft 13A permanent magnet 16 coil 22 first fixed magnetic pole 23 second fixed magnetic pole 24 rotating magnetic pole 25 rotating body 31 displacement sensor T magnetic tape

Claims (3)

(57) [Claims] 1. A rotary head device for recording a signal on a magnetic tape with a magnetic head attached to a rotating drum rotated by a rotating shaft or reproducing a signal recorded on the magnetic tape, wherein a permanent magnetic field is generated. A magnet and a magnetic bearing having the rotating magnetic poles disposed between the magnetic poles of the fixed magnetic field, the magnetic bearing being mounted on the magnetic head, and changing the strength of the fixed magnetic field by flowing a control current to the magnetic head. And a coil for vertically moving the rotary shaft in the axial direction of the rotary shaft. 2. A signal is recorded on a magnetic tape by a magnetic head attached to a rotating body rotated by a rotating shaft and running in a gap formed by an upper fixed drum and a lower fixed drum, or is recorded on a magnetic tape. A rotary head device for reproducing recorded signals, wherein the outer peripheral surfaces of both fixed drums are made elliptical, and the rotary shaft is inclined with respect to the central axis of both fixed drums. A permanent magnet for generating a fixed magnetic field, the magnetic head is mounted, a magnetic bearing composed of rotating magnetic poles disposed between the magnetic poles of the fixed magnetic field, and the strength of the fixed magnetic field by flowing a control current. A coil for changing the position of the magnetic head so as to move the magnetic head up and down in the axial direction of the rotating shaft. 3. The rotary head device according to claim 1, further comprising: a displacement sensor that detects a displacement of the magnetic head; and a driver that controls a current to the coil based on a detection output of the displacement sensor. A rotary head device characterized by being provided.