JP3319477B2 - Phase detection device and rotary drum 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 phase detector suitable for detecting the phase of a rotating drum in a VTR or the like for recording or reproducing information signals such as audio signals and video signals by winding a magnetic tape. The present invention relates to a device and a rotary drum device provided with such a phase detection device.

[0002]

2. Description of the Related Art Conventionally, a rotary head device in a VTR, a DAT or the like is configured as shown in FIG. In FIG. 11, a rotary head device 1 includes a fixed drum 2, a bearing 3 incorporated in the fixed drum 2, and a rotating shaft 4 rotatably supported by the bearing 3 around the center line of the fixed drum. And a rotating drum 5 integrally attached to the rotating shaft 4 and a motor 6 incorporated therein. The outer peripheral edge of the rotating drum 5 includes
A magnetic head 5a is attached.

Here, the motor 6 includes a rotating yoke 7 and a rotor 8 attached to the rotating shaft 4, and a stator substrate 9 attached to the fixed drum 2. Further, a rotor magnet 8a is provided on the upper surface of the rotor 8.
Is attached.

As shown in FIG. 12, the stator substrate 9 has a plurality of coils 9a, 9b, 9c, 9d, 9e, 9
f. On the other hand, the rotor magnet 8a
Are magnetized such that N poles and S poles are alternately arranged along the circumferential direction.

According to the rotary head device 1 configured as described above , at the time of reproduction, each coil 9 on the stator substrate 9 is reproduced.
By supplying a current to each of the coils a to 9f, the magnetic field generated in the coils 9a to 9f acts on each of the N pole and the S pole of the rotor magnet 8a.

As a result, the rotor 8 is rotated together with the rotating shaft 4, the rotating drum 5 and the rotating yoke 7, and the magnetic head 5a provided on the rotating drum 5 causes the magnetic tape 5a to rotate .
The detected signal is output to the outside via the head amplifier. When recording, use the same method as for playback.
The rotating drum 5 rotates , and an electric signal from a control circuit or the like (not shown) is transmitted to the magnetic head 5 via a mechanism (not shown).
a to be written to the magnetic tape.

In this case, the rotor magnet 8a is
As shown in FIG. 3, one of the boundaries between the N pole and the S pole is provided with a projection 8b formed so as to protrude toward the inner circumferential direction. On the other hand, the stator substrate 9 includes the coils 9a
13 to 9f, a phase detection coil 9g is provided as schematically shown in FIG.

As a result, when the rotor 8 rotates, the protrusion 8b of the rotor magnet 8a passes through a position facing the phase detection coil 9g. Thus,
Each time the rotor 8 makes one rotation, the phase detection coil 9g
Since an electromotive force is generated, the rotation of the rotor 8 and its phase are detected by detecting the electromotive force.

[0009]

However, in such a rotary head device 1, since the rotor magnet 8a is provided with the convex portion 8b, the rotational balance of the rotor 8 is deteriorated. Therefore, the rotational balance of the rotor 8 is adjusted in order to minimize the uneven rotation of the rotating shaft 4, the rotating drum 5, the rotating yoke 7 and the rotating components of the rotor 8 so as to obtain a uniform rotating motion of the head 5a. Coordinating work is essential.

Conventionally, this balance adjustment work is performed by scraping the rotating drum 5 itself at a position where the balance is lost,
A balance weight is added to the opposite position on the radially opposite side of this position by soldering or the like.

However, in the case of a precision component such as the rotary drum 5 of the rotary magnetic head device 1,
The soldering position and the balance adjustment amount are limited. For this reason, there has been a problem that the workability is extremely poor and the cost increases. further,
In some cases, it was not possible to achieve perfect balance.

In order to reduce the size of the entire rotary head device 1, it is necessary to reduce the size of the protrusion 8b of the rotor magnet 8a. Therefore, the level of the phase signal is reduced, and the S / N ratio of the phase signal is deteriorated.
There is a problem that the phase of the rotating drum 5 cannot be detected accurately. On the other hand, when the convex portion 8b is enlarged, the convex portion 8
There has been a problem that the influence of b increases and the rotational balance is greatly lost.

In view of the above, the present invention provides a phase detecting device and a rotating drum device which can detect a phase signal reliably with a simple configuration without a rotational balance being lost. The purpose is.

[0014]

SUMMARY OF THE INVENTION According to the present invention, there is provided, in accordance with the present invention, at least one magnetic pole which is magnetized so that N poles and S poles are alternately arranged in a circumferential direction . Magnetic
The boundary between the adjacent magnetic pole adjacent to the pole is the boundary between other magnetic poles.
At least part of the boundary is shifted in the circumferential direction compared to the world
A rotor magnet deformed and magnetized to have a shape ,
A stator substrate fixed and arranged opposite to the rotor magnet; a radially inwardly and outwardly wound stator substrate wound on the stator substrate; and a magnetized portion having the same polarity of the rotor magnet by rotation of the rotor magnet. And a phase detection device comprising two phase detection coils of opposite windings that generate a phase signal in opposition to each other.

[0015] The two phase detection coils may be wound around the stator substrate so as to be shifted inward and outward in the circumferential and radial directions.

The stator is wound around the stator substrate inwardly and outwardly in the circumferential direction and the radial direction, and is opposed to a magnetized portion of a different polarity of the rotor magnet by rotation of the rotor magnet. , And two phase detection coils that generate phase signals and have the same winding direction.

Further, the object is to provide a rotary drum device including a fixed drum and a rotary drum rotatably supported with respect to the fixed drum, wherein the rotary drum has a circular shape with respect to its rotation center. N pole and S along the circumferential direction
A rotor magnet having at least one magnetic pole magnetized so that the poles are alternately arranged and having at least one magnetic pole deformed and magnetized, wherein the fixed drum is wound so as to be shifted inward and outward in the radial direction, and This is achieved by a rotating drum device having two oppositely wound phase detection coils that generate a phase signal by opposing a magnetized portion of the same polarity of the rotor magnet by rotation.

Further, the two phase detection coils may be wound around the stator substrate so as to be shifted inward and outward in the circumferential and radial directions.

Further, the fixed drum is wound around the inner side and the outer side in the circumferential direction and the radial direction so as to be shifted from each other. Can be configured to include two phase detection coils having the same winding direction and generating the same.

[0020]

According to the above construction, the rotor magnet is formed in an annular shape and does not have a projection in the radial direction. Therefore, a rotational balance is good, rotation balun
The adjustment work of the tool becomes remarkably easy.

When each magnetic pole of the rotor magnet passes through the phase detection coil, the electromotive force generated in each phase detection coil is opposite to that of the other. Then, the electromotive forces cancel each other. Here, when the deformed and magnetized magnetic poles of the rotor magnet pass opposite to the phase detection coil, the electromotive force generated in each phase detection coil can cancel each other in the area of the deformed portion. Therefore, the electromotive force is output to the outside.
By detecting the output electromotive force, the rotation and phase of the rotor magnet or the rotating drum are detected.

It is necessary to provide a protrusion on the rotor magnet.
Therefore, the size of the rotor required for driving the motor is sufficient. Obedience
Motor can be downsized,
Can be given.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to FIGS. In addition, since the Examples described below are preferred specific examples of the present invention, various technically preferable limitations are given. However, the scope of the present invention particularly limits the present invention in the following description. The embodiment is not limited to these embodiments unless otherwise stated.

FIG. 1 shows a first embodiment of a rotary head device as a rotary drum device incorporating a phase detecting device according to the present invention. In FIG. 1, a rotary head device 1
Reference numeral 0 denotes a fixed drum 11, a bearing 12 incorporated in the fixed drum 11, and a rotating shaft 1 rotatably supported by the bearing 12 about a center line of the fixed drum 11.
3 and a rotating drum 14 attached to the rotating shaft 13
And a motor 15 and a rotary transformer 16 incorporated therein.

Here, the motor 15 includes a rotating yoke 17 and a rotor 18 attached to the rotating shaft 14 and a stator substrate 19 attached to the fixed drum 11. Further, a rotor magnet 20 is attached to a lower surface of the rotor 18.

The above configuration is the same as that of the conventional rotary head device 1 shown in FIG. 11, but in the rotary head device 10 according to the present invention,
Is configured as shown in FIG. In FIG. 2, the rotor magnet 20 is formed in a ring shape, and is magnetized so that a plurality (four in the illustrated case) of N and S poles are alternately arranged along the circumferential direction. With respect to a boundary 21 between one N pole and an adjacent S pole, a part 21a on the outer peripheral side is formed to be shifted to the N pole side in a crank shape.

On the other hand, the stator substrate 19 (FIG. 11)
2), two phase detection coils 22 and 2 shown in FIG.
Numerals 3 are shifted from each other in the vicinity of the inner peripheral edge and the outer peripheral edge in the radial direction corresponding to the same angular position of the rotor magnet 20 (magnetized portion having the same polarity). In this case, the phase detection coils 22 and 23 are connected in series so that the windings are opposite to each other, and when an electromotive force having substantially the same magnitude and the opposite direction is generated for the same magnetic flux change. In addition, they are configured to cancel each other.

The rotary head device 10 according to the present embodiment is configured as described above.
When the coil formed on the stator substrate 19 is energized, a magnetic field generated in the coil acts on each of the N pole and the S pole of the rotor magnet 20.

As a result, the rotor 18 is connected to the rotating shaft 13,
An electric signal which is rotated together with the rotating drum 14 and the rotating yoke 17 and transmitted from the outside such as a control circuit is transmitted from the fixed drum 11 to the rotating drum 14 via the rotary transformer 16, and is provided on the rotating drum 14. Output to the head 14a. Thereby, the magnetic head 14
In a, writing to a magnetic tape is performed. At the time of reproduction, a signal detected by the magnetic head 14a is transmitted from the rotary drum 14 to the rotary transformer 16a.
Is transmitted to the fixed drum 11 via an external control circuit and output to an external control circuit or the like.

As shown in FIG. 2, a part 21a of the boundary 21 of the magnetic pole of the rotor magnet 20 is shifted, so that the boundary 21
When passing through the position facing the phase detection coils 2 and 23, the change of the magnetic flux linked to the phase detection coils 22 and 23 has a phase difference. Thereby, each phase detection coil 22,
Since the electromotive force generated in 23 also has a phase difference, it cannot cancel each other out, and a signal is output from the coil terminal 24.

The boundary between the other magnetic poles is the phase detection coil 2
When passing through the position facing 2, 23, the phase difference is
Since the electrical angle is approximately 180 degrees, the electromotive forces generated in the phase detection coils 22 and 23 have substantially the same magnitude and cancel each other out, so that no signal is output from the coil terminal 24.

Thus, every time the rotor magnet 20 makes one rotation, a signal is output from the coil terminal 24.

FIG. 3 shows a modification of the rotor magnet of FIG. That is, in FIG.
5 is the boundary 26 of one magnetic pole, and the outer peripheral side 26a is N
The pole side and the inner peripheral side 26b are formed in a crank shape shifted from the S pole side, respectively.

In the case of the rotor magnet 25 having such a shape, the phase can be detected similarly to the rotor magnet 20 of FIG. Further, in this case, since the entire magnetic flux amount of the N pole and the S pole of the rotor magnet 25 is substantially the same, the leakage magnetic flux to the outside is reduced. Therefore, the influence of such a leakage magnetic flux on a rotary transformer or the like is reduced.

FIG. 4 shows another example of the arrangement of the rotor magnet and the phase detection coil. In FIG. 4, FIG.
With respect to the rotor magnet 20 having the same configuration as that described above, the phase detection coils 27 and 28 are arranged at different angular positions of the rotor magnet 20, that is, 360 degrees (n1 × 360 degrees) in electrical angle.
Here, n1 is disposed near the inner peripheral edge and near the outer peripheral edge at angular positions separated by n) .

In this case, the phase detection coils 27 and 28
They are connected in series so that they are wound in opposite directions, and are configured to cancel each other when electromotive forces having substantially the same magnitude and opposite directions are generated for the same magnetic flux change. .

In such a configuration, when the rotor magnet 20 rotates, the outer peripheral portion 21a of the boundary 21 of the magnetic poles
However, when passing through a position facing the phase detection coil 28, electromotive forces of different magnitudes are generated in the phase detection coils 27 and 28, and a phase signal is output from the coil terminal 29.

FIG. 5 shows the rotor magnet 2 shown in FIG.
0 shows a modified example. That is, in FIG. 5, the rotor magnet 30 has an outer peripheral side 31a at the boundary 31 of one magnetic pole on the N pole side and an inner peripheral side 3 at the other boundary 32.
2a are formed in a crank shape shifted to the S pole side.

[0039] When the rotor magnet 30 having such a shape, during rotation of the rotor magnet 30, the outer peripheral portion 31a of the boundary 31 of the magnetic pole, passes through the position opposite to the phase detection coil 28, and the boundary of the magnetic poles 32 inner circumference 32
When “a” passes through a position facing the phase detection coil 27, electromotive forces of different magnitudes are generated in the phase detection coils 27 and 28, and a phase signal is output from the coil terminal 29. Further, in this case, the rotor magnet 30
Since the total magnetic flux amount of the N pole and the S pole is almost the same, the leakage magnetic flux to the outside is reduced. Therefore, the influence on the rotary transformer and the like is reduced.

FIG. 6 shows still another arrangement example of the rotor magnet and the phase detection coil. In FIG. 6, the phase detection coils 33 and 34 are different from the rotor magnet 20 of FIG.
0 different angular positions, that is, 180 degrees in electrical angle ((2n2
-1) It may be 180 degrees. Where n2 is a positive integer
Are disposed near the inner peripheral edge and near the outer peripheral edge, respectively, at angular positions separated by ( number) .

In this case, the phase detection coils 33, 34
They are connected in series so that they have the same winding direction,
An electromotive force of almost the same magnitude and the same direction is generated for the same magnetic flux change, and
When the magnetic flux changes in this way, they are configured to cancel each other.

In such a configuration, when the rotor magnet 20 rotates, the outer peripheral portion 21a of the boundary 21 of the magnetic poles
However, when passing through a position facing the phase detection coil 34, electromotive forces of different magnitudes are generated in the phase detection coils 33 and 34, and a phase signal is output from the coil terminal 35.

FIG. 7 shows the rotor magnet 2 shown in FIG.
0 shows a modified example. That is, in FIG. 7, the rotor magnet 36 has an outer peripheral side 37a at the boundary 37 of one magnetic pole on the N pole side and an inner peripheral side 3 at the other boundary 38.
8a are formed in the shape of a crank, shifted to the opposite N pole side.

In the case of the rotor magnet 36 having such a shape, when the outer peripheral portion 37a of the magnetic pole boundary 37 passes through a position facing the phase detection coil 34 when the rotor magnet 36 rotates , and when the magnetic pole boundary 38 inner circumference 38
When “a” passes through a position facing the phase detection coil 33, electromotive forces of different magnitudes are generated in the phase detection coils 33 and 34, and a phase signal is output from the coil terminal 35.

In the above embodiment, in each of the rotor magnets 20, 25, 30, and 36, a part of the boundary 21, 26, 31, 31, 32, 37, and 38 of one or two magnetic poles is formed in the circumferential direction. And is formed in a crank shape.

However, the shape of the boundary between the magnetic poles is not limited to this. For example, as shown in FIG. 8, the rotor magnet 39 is formed in a ring shape, and a plurality of rotor magnets 39 are formed along the circumferential direction (in the illustrated case). , 4 poles) are magnetized so that N poles and S poles are alternately arranged, and a boundary 40 between one N pole and an adjacent S pole has a part 40 on the outer peripheral side.
It is obvious that a may be formed obliquely shifted to the N pole side.

In this case, the two phase detection coils are:
As shown by reference numerals 41 and 42 in FIG. 9, the rotor magnet 39 is arranged close to each other on the stator substrate near the inner peripheral edge and the outer peripheral edge of the rotor magnet 39, thereby achieving a small size. Further, if the phase detection coils 41 and 42 are arranged too close to each other, the magnetic fields affect each other. Therefore, if there is room in the mounting space, as shown in FIG.
Are relatively separated from each other, so that the S / N ratio is improved.

[0048]

As described above, according to the present invention, since the rotor magnet is formed in an annular shape, the rotation balance is good, and the rotation of the rotor magnet having the irregular shape is improved. The work of adjusting the balance becomes unnecessary. Therefore, the operation of adjusting the rotational balance of the entire rotating drum becomes extremely easy. Also, when the rotor magnet is deformed and magnetized, a phase signal is extracted from each phase detection coil when the deformed portion passes through the phase detection coil so that the rotor magnet can be easily configured. become.
Also, there is no need to provide a protrusion on the rotor magnet.
Therefore, the size of the rotor required for driving the motor may be sufficient. Follow
The motor can be downsized, contributing to the downsizing of the whole device.
You.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing one embodiment of a rotary head device provided with a phase detection device according to the present invention.

FIG. 2 is a plan view showing a first arrangement example of a rotor magnet and a phase detection coil in the rotary head device of FIG. 1;

FIG. 3 is a plan view showing a modification of the rotor magnet of FIG. 2;

FIG. 4 is a plan view showing a second arrangement example of a rotor magnet and a phase detection coil in the rotary head device of FIG. 1;

FIG. 5 is a plan view showing a modified example of the rotor magnet of FIG. 4;

FIG. 6 is a plan view showing a third arrangement example of a rotor magnet and a phase detection coil in the rotary head device of FIG. 1;

FIG. 7 is a plan view showing a modification of the rotor magnet of FIG. 6;

FIG. 8 is a plan view showing a modification of the rotor magnet of FIG. 2;

FIG. 9 is a partially enlarged view showing an example of an arrangement of a phase detection coil with respect to the rotor magnet of FIG. 8;

FIG. 10 is a partially enlarged view showing another arrangement example of the phase detection coil with respect to the rotor magnet of FIG. 8;

FIG. 11 is a schematic sectional view showing an example of a rotary head device provided with a conventional phase detecting device.

12 is an exploded perspective view of a stator substrate and a rotor magnet in the rotary head device of FIG.

FIG. 13 is a plan view of a rotor magnet in the rotary head device of FIG.

[Explanation of symbols]

 Reference Signs List 10 rotating head device 11 fixed drum 12 bearing 13 rotating shaft 14 rotating drum 15 motor 16 rotary transformer 17 rotating yoke 18 rotor 19 stator substrate 20 rotor magnet 21 magnetic pole boundary 22 phase detection coil 23 phase detection coil 24 coil terminal 25 rotor magnet 26 Magnetic pole boundary 27 Phase detection coil 28 Phase detection coil 29 Coil terminal 30 Rotor magnet 31 Magnetic pole boundary 32 Magnetic pole boundary 33 Phase detection coil 34 Phase detection coil 35 Coil terminal 36 Rotor magnet 37 Magnetic pole boundary 38 Magnetic pole boundary 39 Rotor magnet 40 boundary of magnetic pole 41 phase detection coil 42 phase detection coil

Claims (6)

(57) [Claims] And 1. A N poles and S poles along the circumferential direction are magnetized to alternating, and at least one magnetic pole, this
The boundary between one magnetic pole and the adjacent magnetic pole is
At least a portion of the boundary is circumferential
A rotor magnet deformed and magnetized so as to have a deviated shape, a stator substrate fixedly arranged to face the rotor magnet, and wound on the stator substrate so as to be shifted radially inward and outward. A phase detection device comprising: two phase detection coils of opposite windings that generate a phase signal by facing a magnetized portion having the same polarity of the rotor magnet by rotation of the rotor magnet. 2. The phase detection device according to claim 1, wherein the two phase detection coils are wound on the stator substrate so as to be shifted inward and outward in a circumferential direction and a radial direction. . 3. The stator substrate is wound around the stator substrate so as to be shifted inward and outward in the circumferential direction and the radial direction, and is opposed to a magnetized portion having a different polarity of the rotor magnet by rotation of the rotor magnet. The phase detection device according to claim 1, further comprising two phase detection coils for generating a phase signal and having the same winding direction. 4. A rotary drum device comprising a fixed drum and a rotary drum rotatably supported with respect to the fixed drum, wherein the rotary drum extends in a circumferential direction with respect to a center of rotation thereof. And a rotor magnet magnetized so that N and S poles are alternately arranged and at least one magnetic pole is deformed and magnetized, and the fixed drum is wound so as to be shifted inward and outward in the radial direction. A rotating drum device comprising: two phase detection coils of opposite windings that generate a phase signal by facing the same-polarity magnetized portion of the rotor magnet by rotation of the rotor magnet. 5. The rotary drum device according to claim 4, wherein the two phase detection coils are wound on the stator substrate so as to be shifted inward and outward in a circumferential direction and a radial direction. . 6. The fixed drum is wound in a circumferentially and radially inwardly and outwardly displaced manner, and is rotated by rotation of the rotor magnet so as to face a magnetized portion having a different polarity of the rotor magnet to generate a phase signal. 5. The rotary drum device according to claim 4, further comprising two phase detection coils having the same winding direction for generating a phase difference.