JPH05342706A - Phase detector - Google Patents

Abstract

PURPOSE:To enhance the S/N ratio of a phase detector. CONSTITUTION:A PG coil 21 which has been wound on a stator substrate 20 and which detects a PG signal is provided with the following: a radial-direction patterns 22a, 22b which have been arranged so as to make a prescribed angle at the circumference (20 deg. in the figure) in the radial direction of said substrate 20; and a nearly V-shaped obliquely running pattern 23 which is connected to, and brought into contact with, said radial-direction patterns 22a, 22b and which runs obliquely with reference to said radial-direction patterns 22a, 22b. The interior angle A of said obliquely running patterns 23 is set at an angle at the circumference (20 deg. in the figure) formed by said radial-direction patterns 22a, 22b. When the magnetization part, for PG signal use, of a rotor magnet is passed on said PG coil 21, the PG signal is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for use in detecting the phase of a rotary head cylinder in a VTR device for recording or reproducing information signals such as audio signals and video signals by winding a magnetic tape. The present invention relates to a detection device.

[0002]

2. Description of the Related Art FIG. 3 is a cross-sectional view showing a cross section of an example of the configuration of a conventional rotary head cylinder. 4 is a plan view showing the planar configuration of the rotor magnet 7 of FIG. 3, and FIG. 5 is a plan view showing the planar configuration of the stator substrate 8 of FIG. 3 (only 8a is visible in FIG. 3). FIG. 6 is a side view thereof. The configuration of the conventional phase detecting device for the rotary head cylinder will be described below with reference to FIGS.

In FIG. 3, a rotary drum 4 having a magnetic recording head 3 provided on the outer periphery thereof is fixed above a rotary shaft 2 of a motor 1. Bearings 6a and 6b mounted below the fixed drum 5 of the motor 1 rotatably support the rotating shaft 2. Further, a disc-shaped rotor magnet 7 is fixed to the rotating shaft 2. As shown in FIG. 4, the rotor magnet 7 has a drive magnetizing portion 9 in which N poles and S poles are alternately magnetized in a circumferential direction at a cycle of 30 °, and further adjacent N magnets are provided. A PG signal magnetizing unit 10 is provided in which a part of the outer circumferences of the pole and the S pole are projected in the circumferential direction.

Further, a stator substrate 8 arranged so as to face the rotor magnet 7 with an appropriate gap.
Are fixed to the fixed drum 5. As shown in FIGS. 5 and 6, the stator substrate 8 has a rotor magnet 7
On the side, the PG coil 15 for detecting the PG signal and the FG
It has a PG / FG coil substrate 8a on which an FG coil 16 for detecting a signal is wound, and drive coil substrates 8b and 8c on which a driving coil (not shown) is wound are laminated on the upper layer thereof. Here, the PG coil 15 is arranged so as to face when the PG signal magnetizing unit 10 of the rotor magnet 7 rotates and passes.

Furthermore, the angle formed by the circumferential width of the PG coil 15 of the stator substrate 8 is set to 20 °,
It is wound so as to have a substantially fan shape. FG coil 16
Is wound so as to circulate on the circumference of the stator substrate 8 so as to have a substantially U-shape with a circumferential angle of 60 °.

Next, the operation of the above configuration will be described.

When a drive current is supplied to the drive coils of the drive coil substrates 8b and 8c, the rotor is determined by the relationship between the direction of the current flowing through the drive coil and the direction of the magnetic field of the drive magnetizing portion 9 of the rotor magnet 7. An electromagnetic force in the circumferential direction acts on the magnet 7. The electromagnetic force is transmitted to the rotary shaft 2 via the rotor magnet 7, and the rotary shaft 2 is rotated to rotate the rotary drum 4 fixed to the rotary shaft 2 together with the head 3.

Further, as the rotor magnet 7 rotates, the PG signal magnetizing portion 1 of the rotor magnet 7 is rotated.
When 0 passes over the PG coil 15 of the stator substrate 8, an induced electromotive force acts on the PG coil 15 by the magnetic flux of the PG signal magnetizing unit 10. By the above action,
Induction current is generated in the PG coil 15. This induced current is detected as a PG signal. That is, one rotation of the rotor magnet 7 detects one PG signal (pulse).

[0009]

However, in the phase detecting device having the above-mentioned configuration, the PG coil 15 has the PG
Along with the action of the magnetic flux of the signal magnetizing unit 10, the leakage magnetic flux of the drive magnetizing unit 9 magnetized in the circumferential direction acts. There is a problem in that the action of the leakage magnetic flux causes noise, which reduces the S / N ratio of the PG signal.

Further, since the PG signal magnetizing portion 10 is structured so as to protrude from the outer diameter portion of the rotor magnet 7,
Rotor magnet 7 and stator substrate 8 facing it
Has a problem in that the motor 1 is increased in size.

The present invention has been made to solve the above problems, and an object thereof is to improve the S / N ratio of a PG signal. Further, it is intended to reduce the size of the motor.

[0012]

To achieve the above object, in the phase detector according to the present invention, the PG coil 21 of the stator substrate 20 has a predetermined circumferential angle in the radial direction of the stator substrate 20 (embodiment). The radial patterns 22a and 22b arranged so as to form an angle of 20 °) are connected to the radial patterns 22a and 22b, and are arranged in a substantially dog-legged shape oblique to the radial patterns 22a and 22b. It is characterized by having a diagonal pattern 23.

Further, the angle formed by the internal angle A of the oblique pattern 23 is greater than the circumferential angle at which the radial patterns 22a and 22b are arranged.

[0014]

In the phase detector having the above structure, the PG coil 21 on the stator substrate 20 is hardly affected by the leakage magnetic flux of the rotor magnet 7, and the magnetic flux of the PG signal magnetizing portion 10 of the rotor magnet 7 is generated. A PG signal can be obtained by the induced electromotive force due to the action. Therefore, the S / N ratio of the PG signal can be improved.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a stator substrate 20 is provided instead of the conventional stator substrate 8. Other than that, the configuration of an embodiment of the rotary head cylinder to which the present invention is applied is the same as that of the conventional example shown in FIG. The same parts as those of the conventional example shown in FIG. 3 are designated by the same reference numerals, and the overlapping description will be appropriately omitted.

FIG. 1 is a plan view showing a planar structure of a stator substrate 20 of the present invention. An embodiment of the rotary head cylinder phase detection device of the present invention will be described below with reference to FIG.

In FIG. 1, the stator substrate 20 has an FG coil 16 for detecting an FG signal, as in the conventional example.
It has a PG / FG coil substrate 20a on the surface of which a PG coil 21 for detecting a PG signal is wound, and further, like the conventional example, a drive coil substrate on which a drive coil is wound.
8b and 8c are overlaid (in FIG. 1, only the PG / FG coil substrate 20a is visible). The PG coil 21 is
The rotor magnet 7 is arranged so as to face each other when the PG signal magnetizing unit 10 rotates and passes.

The PG coil 21 has radial patterns 22a and 22b arranged in a radial direction of the stator substrate 20 so as to form a circumferential angle of 20 ° with each other.
It has a diagonal pattern 23 which is connected to the radial patterns 22a and 22b and is arranged obliquely with respect to the radial patterns 22a and 22b and has a substantially V shape.

Further, the angle A formed by the internal angle of the oblique pattern 23 is set to be equal to or larger than the angle (20 ° in the embodiment) formed by the radial patterns 22a and 22b (for example, 90 °). Is set.

The rotary head cylinder having the stator substrate 20 according to the embodiment of the present invention having the above structure can rotate the rotary shaft 2 by the same operation as the operation described in the conventional example. Further, by the same operation as the operation described in the conventional example, an induced current is generated in the PG coil 21 and the PG signal can be detected.

Further, similarly to the conventional example, the leakage magnetic flux of the drive magnetizing portion 9 of the rotor magnet 7 acts on the PG coil 21. However, the winding direction of the oblique pattern 23 of the PG coil 21 and the direction of the leakage magnetic flux of the rotor magnet 7 are oblique (to be closer to parallel).
Since it is provided, the induced current due to the action of the leakage magnetic flux generated in the PG coil 21 becomes extremely small. Therefore, the PG coil 21 can detect the PG signal with almost no influence of the leakage magnetic flux.

Next, another embodiment of the phase detector of the present invention is shown in FIG. FIG. 2A is a plan view showing a planar configuration of the rotor magnet 30, and FIG. 2B is a plan view showing a planar configuration of the stator substrate 40.

In FIG. 2A, a disc-shaped rotor magnet 30 has an N pole and an S pole 30 from the center of the rotor magnet 30 along the circumferential direction of the rotor magnet 30.
It has drive magnetizing portions 32 which are alternately magnetized at a magnetizing cycle of .degree .. In addition, a PG signal magnetizing portion 31 is provided, which is magnetized as an S pole on a part of the outer periphery of the N pole and is connected to the S poles located on both sides of the N pole. Therefore, the PG signal magnetizing portion 31 is magnetized to the S pole within a range of 90 ° from the center of the rotor magnet 30.

In FIG. 2B, a stator substrate 40 is provided with an FG coil 16 for detecting an FG signal and a PG / FG coil substrate 40a having PG coils 41a, 41b for detecting a PG signal wound on its surface. In addition, as in the conventional example, the drive coil substrate 8 has a drive coil wound thereon.
a and 8b are layered (in FIG. 2B, PG / F
Only the G coil substrate 40a is visible).

The PG coils 41a and 41b form a circumferential angle of 30 ° with each other in the radial direction of the stator substrate 40 (the same circumferential angle as the magnetization period of the drive magnetizing portion 32 of the rotor magnet 30). As described above, they are arranged in series.
Further, the PG coils 41a and 41b are arranged so as to face each other when the PG signal magnetizing portion 31 of the rotor magnet 30 rotates and passes.

Further, the PG coils 41a are arranged in the radial direction of the stator substrate 40 so as to form a circumferential angle of 20 ° with each other.
b, and a diagonal pattern 43a which is connected to the radial patterns 42a and 42b and is arranged obliquely with respect to the radial patterns 42a and 42b and has a substantially V shape. Similarly, the PG coil 41b has a radial pattern 42c,
42d and a diagonal pattern 43b.

Furthermore, the oblique patterns 43a and 43b
The angle B formed by the inner angles of the
b, or an angle (eg, 20 ° in the embodiment) of the circumferential direction formed by the radial patterns 42c and 42d or more (for example, 9).
0 °).

The rotary head cylinder having the rotor magnet 30 and the stator substrate 40 configured as described above can rotate the rotary shaft 2 by the same operation as described in the conventional example.

Next, the operation of the phase detector having the above structure will be described.

When the drive magnetized portion 32 of the rotor magnet 30 passes over the PG coils 41a and 41b of the stator substrate 40 due to the rotation of the rotor magnet 30, the change in the magnetic pole of the drive magnetized portion 32 causes 2 PGs
An induced electromotive force acts on the coils 41a and 41b. However, the induced electromotive force that acts on the PG coil 41a and the induced electromotive force that acts on the PG coil 41b are forward and reverse induced electromotive forces, so the induced electromotive force is canceled out, and the PG coil 41 is canceled.
No induced current is generated in a and 41b, and the PG signal is not detected.

On the other hand, the PG signal magnetizing unit 31 is
When passing over the two PG coils 41a and 41b, P
Due to the change in the magnetic pole of the G signal magnetizing unit 31, the change in magnetic flux acts only on one PG coil, and the change in magnetic flux does not act on the other PG coil. To work. Therefore, the PG signal magnetizing unit 31
The induced current is generated and the PG signal can be detected only when the electric field passes over the PG coils 41a and 41b. As a result, the PG signal (pulse) can be detected once by the rotor magnet 30 rotating once.

Leakage magnetic flux is generated by the magnetic pole changing portions 33a and 33b whose magnetic poles in the circumferential direction of the PG signal magnetizing portion 31 change, and act on the PG coils 41a and 41b, respectively. However, as in the embodiment of FIG. 1, the oblique pattern 43 of the PG coils 41a and 41b is used.
Since the winding directions of a and 43b and the directions of the leakage magnetic flux from the magnetic flux changing portions 33a and 33b of the rotor magnet 30 are provided so as to be oblique (closer to be parallel to each other), the PG coil 41a is provided. , 41b, the induced current due to the action of the leakage magnetic flux becomes extremely small. Therefore,
The PG coils 41a and 42b can detect the PG signal without being affected by the leakage magnetic flux.

In the embodiment of FIG. 2, since the rotor magnet 30 is formed so that the drive magnetizing portion 32 and the PG signal magnetizing portion 31 have the same diameter, the rotor magnet 30 is formed as in the example of FIG. Compared with the case, the diameters of the rotor magnet 30 and the stator substrate 40 can be reduced, and the motor can be downsized.

[0034]

As described above, according to the phase detector of the present invention, the PG coil of the stator substrate is provided with the oblique pattern so that the influence of the leakage magnetic flux from the magnetizing portion for driving the rotor magnet is affected. Received almost no P
The G signal can be detected. Therefore, noise can be reduced and the S / N ratio can be improved.

[Brief description of drawings]

FIG. 1 is a plan view showing a planar configuration of an embodiment of a stator substrate 20 of the present invention.

FIG. 2 is a plan view showing a planar configuration of another embodiment of the rotor magnet 30 and the stator substrate 40 of the present invention.

FIG. 3 is a cross-sectional view showing an example of the configuration of a conventional rotary head cylinder.

FIG. 4 is a plan view showing a planar configuration of a rotor magnet 7 of FIG.

5 is a plan view showing a planar configuration of a stator substrate 8 of FIG.

6 is a side view showing a more detailed configuration of the stator substrate 8 of FIG.

[Explanation of symbols]

 1 Motor 2 Rotating Shaft 3 Head 4 Rotating Drum 5 Fixed Drum 6a, 6b Bearing 7 Rotor Magnet 8 Stator Substrate 9 Drive Magnetizing Part 10 PG Signal Magnetizing Part 15 PG Coil 16 FG Coil 20 Stator Substrate 20a PG / FG Coil Substrate 21 PG coil 22a, 22b Radial direction pattern 23 Oblique pattern 30 Rotor magnet 31 PG signal magnetizing part 32 Driving magnetizing part 40 Stator substrate 40a PG / FG coil substrate 41a, 41b PG coil 42a, 42b, ... Radial pattern 43a, 43b Diagonal pattern

Claims (1)

[Claims] 1. A drive magnetizing section in which N and S poles are alternately magnetized in a circumferential direction, and a P for generating a magnetic flux for PG signal detection.
A rotor magnet having a magnetizing portion for G signal, and a PG coil which is arranged so as to face the rotor magnet and obtains a PG signal by a change in magnetic flux of the magnetizing portion for PG signal of the rotor magnet. A stator substrate mounted on the stator substrate, wherein the PG coil of the stator substrate is arranged in a radial direction of the stator substrate so as to form a predetermined circumferential angle; And a diagonal pattern that is connected to the radial pattern and is arranged obliquely with respect to the radial pattern, wherein an angle formed by an inner angle of the diagonal pattern is a predetermined value in which the radial pattern is arranged. A phase detection device having an angle equal to or greater than the circumferential angle of.