JPH0610812U - Motor with rotation phase detection mechanism - Google Patents

Abstract

(57) [Abstract] [Purpose] The purpose of the motor with a rotational phase detection mechanism of the present invention is to provide a highly accurate P motor that does not cause torque unevenness.
A G output can be obtained, a motor can be downsized, and a highly productive motor can be obtained with a simple design. A motor with a rotation phase detecting mechanism is arranged so as to face a rotor 8 having a ring-shaped permanent magnet 5 magnetized in multiple poles in a circumferential direction at a constant magnetization angle pitch P1 and a permanent magnet 5. The drive coil 9 and the PG coil 17 are provided.
The one pole 5d of the permanent magnet 5 has a convex portion 5d protruding toward the center.
1 is provided. The PG coil 17 is arranged so as to substantially face the convex portion 5d1, and the winding width W3 in the circumferential direction thereof is 2n times the magnetization angle pitch P1 of the permanent magnets 5 (n = 1, 2,
3, ...).

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a motor with a rotation phase detecting mechanism used for a rotating drum such as a VTR.

[0002]

[Prior art]

 The rotary drum used in a VTR or the like shown in FIG. 3 has a well-known structure in which an upper drum 4 provided with a magnetic head is rotatably supported by a shaft 3 fixed to a lower drum 1 via a bearing 3. A motor for rotating the upper drum 4 is provided as follows.

That is, the upper drum 4 is provided with a rotor 8 composed of a yoke 6 and a yoke 7 to which an annular permanent magnet 5 is fixed, and a drive coil 9 is provided above the shaft 2 on a substrate 10 The stator 11 arranged at 10a is attached. As shown in FIG. 4, the permanent magnet 5 is magnetized alternately with N, S, N, S, ... Along the circumferential direction at a constant magnetizing angle pitch P1. In this example, the magnetization angle pitch P1 is 30 °. Further, nine drive coils 9 are arranged facing the permanent magnet 5.

Now, in order to synchronize with a TV signal in the VTR, it is necessary to have information on which magnetic head is located at which position on the tape. For this reason, a mechanism (rotational phase detection mechanism) that generates a PG output each time the upper drum 4 makes one rotation is often incorporated in the motor. Therefore, conventionally, the rotor 8 and the stator 11 are configured as follows.

First, as shown in FIG. 5, one pole 5 a of the permanent magnet 5 of the rotor 8 is partially magnetized to the opposite pole portion 5 a 1, and the PG coil 13 is arranged on the lower surface 10 b of the substrate 10 of the stator 11. There is something I did. The winding width W1 of the PG coil 13 in the circumferential direction is twice the magnetizing angle pitch P1 of the permanent magnets 5, and in the example shown in the figure, the number of magnetized magnetic poles is 12 and the winding width is 60 °. In addition, 14a and 14b are lands provided for connecting electric wires for extracting a signal to both ends of the PG coil 13.

When the rotor 8 rotates together with the upper drum 4, the voltages shown in FIGS. 6A and 6B are generated in the radial portions 13a and 13b of the PG coil 13, and the PG coil 13 as a whole is generated. The voltage (PG output) is the sum of (a) and (b) in the figure and is as shown in (c) in the figure. Each time the rotor 8 makes one rotation, one pulse is generated at the top and one pulse at the bottom. Therefore, if these pulses are passed through the waveform shaping circuit and replaced with one pulse output, the rotation phase can be detected from this. .

Further, as shown in FIG. 7, the continuous two poles 5b and 5c of the permanent magnet 5 of the rotor 8 are provided with the convex portions 5b1 and 5C1 protruding in the center direction, respectively, and facing the convex portions 5b1 and 5C1. In some cases, the PG coil 15 is arranged on the lower surface 10b of the substrate 10 of the stator 11 so as to fit each other. The winding width W2 of the PG coil 15 in the circumferential direction is the same as the magnetizing angle pitch P1 of the permanent magnet 5, and is 30 ° in this example.

A voltage is generated in the PG coil 15 by the rotation of the rotor 8 together with the upper drum 4, which is shown in FIG. 8A due to the influence of the permanent magnet 5 other than the convex portions 5b1 and 5C1. Therefore, the canceling coil 16 is connected to the PG coil 15 in order to cancel this effect. The canceling coil 16 is arranged outside the PG coil 15 and at a position facing a magnetic pole having a polarity opposite to that of the PG coil 15. The winding width W4 of the canceling coil 16 is the same as that of the PG coil 15, and the number of turns is equal to that of the PG coil 15. Is generally less than. The voltage generated in the canceling coil 16 is as shown in FIG. 7B, and the voltage (PG output) in the entire coil (PG coil 15 and canceling coil 16) is as shown in FIG. Become. When the rotor 8 makes one rotation, vertical pulses are generated, and if these pulses are passed through the waveform shaping circuit and replaced with one pulse output, the rotational phase can be detected from now on.

[0009]

[Problems to be solved by the device]

 However, in the former motor, since one pole 5a of the permanent magnet 5 that constitutes the magnetic circuit together with the drive coil 9 is partially magnetized in the opposite pole portion 5a1, there is a possibility that torque unevenness of the motor may occur, and PG The coil 13 is liable to move closer to the outer circumference of the stator 11 and restricts the layout of the coil for driving, or the description is omitted, but the layout of the frequency generating mechanism for speed detection often incorporated in this type of motor is restricted. However, there was a problem that the motor could not be miniaturized.

On the other hand, in the latter motor, it is difficult to set the voltage of the PG coil 15 and the voltage of the canceling coil 16 so as to completely cancel the unnecessary portion as the PG output due to the restriction on the arrangement. As shown in), the output other than once per rotation is detected, which causes an error in waveform shaping, and the land for extracting the output inside the PG coil 15 secures the area required for wiring. However, there was a problem that it could not be miniaturized.

[0011]

[Means for Solving the Problems]

 The present invention solves the above-mentioned problems, and a rotor provided with an annular permanent magnet magnetized in a circumferential direction with multiple poles at a constant magnetizing angle pitch, and a rotor arranged to face the permanent magnet. In a motor with a rotational phase detecting mechanism, which comprises a driving coil and a stator having a PG coil, a convex portion protruding toward the center is provided on one pole of the permanent magnet, and the PG coil substantially faces the convex portion. And the winding width in the circumferential direction is set to 2n times (n = 1, 2, 3, ...) The magnetizing angle pitch of the permanent magnets. To do.

[0012]

【Example】

 Hereinafter, the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of a motor with a rotational phase detecting mechanism of the present invention, and FIGS. 2 (a), 2 (b) and 2 (c) are diagrams showing a voltage induced by a PG coil. . The parts corresponding to the parts described in the section of the conventional example are given the same reference numerals. Also in the motor with the rotational phase detecting mechanism of the present embodiment, as shown in FIG. 4, the rotor 8 including the annular permanent magnet 5 magnetized in multiple poles at the constant magnetization angle pitch P1, and the rotor 8 It is composed of a permanent magnet 5 and a stator 11 provided with a drive coil 9 arranged so as to face the permanent magnet 5, and the structure is as follows.

As shown in FIG. 1, one pole 5d of the permanent magnet 5 of the rotor 8 is provided with a convex portion 5d1 protruding toward the center, and the lower surface 10b of the substrate 10 of the stator 11 has a convex portion 5d1. The PG coil 17 is arranged so as to face with. The winding width W3 of the PG coil 17 in the circumferential direction is set to be approximately twice the magnetizing angle pitch P1 of the permanent magnet 5. In this example, the number of magnetizing poles is 12, and the magnetizing angle pitch P1 is 30 °. The width W3 is 60 °.

With this configuration, as the rotor 8 rotates, the radial portions 17a and 17b of the PG coil 17 receive the same change in magnetic field due to the permanent magnets 5, and the protrusions 5d1 other than the protrusions 5d1 protruding toward the center are provided. Although the magnetic poles do not directly face the PG coil 17, small voltages in opposite directions are generated due to the influence of the leakage magnetic field. Further, each of the radial portions 17a and 17b is subjected to a strong magnetic field change when passing over the convex portion 5d1, and a large voltage is generated there. FIG. 2A shows the voltage waveform between the terminals of the PG coil and the time axis, and FIG. 2B shows the radial portion 17a and the radial portion 17b. A voltage of the sum of these is generated at the terminals of the PG coil 17, and a voltage waveform as shown in FIG. 2 (c) is generated between the terminals, and the rotor 8 is pulsed up and down as it makes one rotation. Since these pulses are generated one by one, if these pulses are passed through a waveform shaping circuit and replaced with one pulse output, this can be used for rotational phase detection.

In this motor with a rotational phase detection mechanism, one pole of the permanent magnet 5 that constitutes the magnetic circuit together with the drive coil 9 is not partially magnetized to the opposite pole, so torque unevenness of the motor does not occur. . Further, since the PG coil 17 is arranged on the inner peripheral side of the stator 8 so as to face the convex portion 5d1 of the permanent magnet 5, the PG coil 17 is provided on the outer peripheral side for the drive coil of the motor and the speed detection not described. Since it can be used for a frequency power generation mechanism and the like, the motor can be downsized, and the winding width W3 in the circumferential direction of the PG coil 17 is limited to one pole only for the convex portion 5d1 of the permanent magnet 5. By setting the magnetizing angle pitch to be approximately twice as large as the magnetizing angle pitch, the PG coil itself has an effect of also serving as a coil for canceling unnecessary voltage, a highly accurate PG output can be obtained, and the design is simplified. Further, by setting the winding width W3 of the PG coil 17 in the circumferential direction to be approximately twice the magnetizing pitch P1, the area of the central portion of the PG coil 17 can be increased and the output inside the coil can be taken out. It is possible to increase the area of the land portions 14a and 14b, and thus it is possible to provide a motor with high productivity.

In the present embodiment, the winding width W3 of the PG coil 17 in the circumferential direction is twice the magnetizing angle pitch P1 of the permanent magnets 5, but if it is a positive multiple of 2, then the convex portion 5d1 is formed. It goes without saying that it is possible to prevent the influence of the magnetic flux of the permanent magnet 5 except for. Further, it can be seen from FIG. 1 that the width in the circumferential direction of the convex portion 5d1 of the permanent magnet 5 matches the width of one magnetic pole, but it goes without saying that the same effect can be obtained if the width is smaller than this.

[0018]

[Effect of device]

 As can be seen from the above description, in the motor with the rotational phase detection mechanism of the present invention, the torque unevenness of the motor does not occur, the PG output with high accuracy is obtained, the motor can be downsized, and the productivity is high. The effect is that the motor can be obtained with a simple design.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a motor with a rotational phase detecting mechanism of the present invention.

2 (a), (b) and (c) are explanatory diagrams showing voltages generated in a PG coil.

FIG. 3 is a sectional view showing a rotary head of a VTR.

FIG. 4 is a perspective view showing a rotor and a stator that constitute a motor.

FIG. 5 is a perspective view showing an example of a conventional motor.

6 (a), (b) and (c) are explanatory views showing voltages generated in a PG coil.

FIG. 7 is a perspective view showing another example of a conventional motor.

8A, 8B, and 8C are explanatory diagrams showing voltages generated in the PG coil and the canceling coil.

[Explanation of symbols]

 5 Permanent magnet 8 Rotor 9 Drive coil 11 Stator 17 PG coil P1 Magnetization angle pitch W3 Winding width

Claims (1)

[Scope of utility model registration request] 1. A rotor provided with an annular permanent magnet magnetized in multiple poles in a circumferential direction at a constant magnetization angle pitch, a drive coil and a PG coil arranged so as to face the permanent magnet. In a motor with a rotation phase detecting mechanism including a stator, a convex portion protruding toward the center is provided on one pole of the permanent magnet, and the PG coil is arranged so as to substantially face the convex portion,
A motor with a rotation phase detecting mechanism, wherein the winding width in the circumferential direction is 2n times (n = 1, 2, 3, ...) The magnetizing angle pitch of the permanent magnets.