JP3075073U - Rotary drum motor rotation position detector - Google Patents

Abstract

(57) [Problem] To provide an apparatus for detecting the rotational position of a rotary drum motor, which does not require a separate magnet for the magnetic pole for detecting the rotational position, reduces costs, and adversely affects jitter on a video screen. Avoid performance degradation. A rotor driving magnetic pole of a rotor magnet is provided so as to face a stator core in a circumferential direction, and a position detecting magnetizing pole is provided on the rotor magnet.
The detection sensor is provided at the position of the rotation driving magnetic pole having the same polarity as the magnetization polarity, and the detection sensor is arranged to face the end surface of the rotor magnet 14. This eliminates the influence of jitter on the video screen and reduces the performance degradation.

Description

[Detailed description of the invention]

[0001]

[Technical field to which the invention belongs]

 The present invention is used for driving a rotating head cylinder of a magnetic recording / reproducing device such as a video cassette recorder (VCR), and detects a change in a magnetic field due to rotation of a rotor magnet with a sensor to obtain a rotation position signal. It relates to a position detection device.

[0002]

[Prior art]

 Conventionally, in this type of rotary drum motor, a rotating position detecting magnetizing pole provided on a rotor magnet of the rotary drum motor and a detection sensor provided on a fixed side for detecting a position are used. A detection device that detects a rotational position by detecting a magnetic field change due to rotation with a coil sensor, and outputs one pulse (PG pulse: a video head switching signal) for one rotation of the rotary drum motor. Are generally known (see, for example, JP-A-63-11054, JP-A-5-227721, JP-A-8-65988, and the like).

[0003]

[Problems to be Solved by the Invention] However, in the conventional device, the magnetized pole for detecting the rotational position is provided on the outer peripheral surface of the rotor case of the rotor magnet and a magnet is separately provided, and the detection is performed on the outer peripheral surface. However, since a separate magnet was required, the cost was high. In addition, the positional relationship between the magnetized pole for detecting the rotational position and the magnetic pole for rotating the rotor magnet is not appropriate (specifically, the magnetized pole for detecting the rotational position has a polarity opposite to that of the rotor magnet having the opposite polarity). It is found that the video screen is adversely affected by jitter and the performance is greatly deteriorated.

The present invention solves the above-mentioned conventional problems. By devising the formation of the rotating position detecting magnetized pole, a separate magnet is not required for the magnetized pole and the cost is reduced. It is another object of the present invention to provide a rotary drum motor rotational position detecting device which reduces the video screen and does not cause adverse effects of jitter or performance degradation on a video screen.

[0005]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention provides a rotor magnet having a magnetic pole for rotational driving, a stator core on which a stator coil is wound facing the rotor magnet, and a position detector provided on the rotor magnet. A rotation position detection device for a rotary drum motor, comprising: a magnetizing pole for use; and a detection sensor for detecting a position, wherein a magnetic field change due to rotation of the rotor magnet is detected by the detection sensor to obtain a rotation position signal. The rotation driving magnetic pole is provided so as to oppose the stator core in the circumferential direction, and the position detecting magnetization pole is an end face of the rotor magnet and has the same polarity as the magnetization polarity. The detection sensor is provided at a position of a magnetic pole, and the detection sensor is disposed at a position facing an end face of the rotor magnet.

[0006] In the above configuration, the end face of the rotor magnet may be magnetized to provide the position detection magnetized pole, and another magnet is not required. In addition, since the position detecting magnetizing pole is provided at a position having the same polarity as that of the rotation magnetizing pole of the rotor magnet, the effect of jitter on the video screen is reduced, and the performance deterioration is reduced.

In the above, a circuit board for controlling energization of the stator coil may be provided, and the detection sensor may be fitted and arranged in a hole formed in the circuit board. Thus, in a configuration in which the detection sensor is disposed on the fixed-side circuit board, the distance between the circuit board and the facing surface of the end surface of the rotor magnet can be reduced, and the axial dimension of the rotary drum motor can be reduced.

Further, in the above, it is preferable that the detection sensor is formed of a coil, and an axial direction of the detection sensor is arranged parallel to an end face of the rotor magnet. As a result, an axial (vertical) coil may be used as the detection sensor coil, and the cost can be reduced.

[0009]

[Embodiment of the invention]

 Hereinafter, an embodiment of the device according to the present invention will be described with reference to the drawings. FIG. 1 shows a video cylinder head provided with a rotary drum motor rotational position detecting device. The cylinder head 1 includes a head motor 2, a rotary head 3 having a video head, a fixed head 4, and a fixed support shaft 5. The head motor 2 has a plurality of core magnetic poles around which a stator coil 12 is wound, and a stator core 11 fixed to a fixed support shaft 5 via a boss, and an annular rotor magnet provided to face the outer periphery thereof. It comprises a rotatable rotor (rotor case) 13 that holds 14 and a circuit board 15 fixed to the stator core 11. The rotary head 3 is coupled to the rotor 13 and is integrally rotated.

As shown in FIG. 2, the rotor magnet 14 has a plurality of N, S magnetic poles (8 poles × 2) formed on a circumferentially facing surface, and generates a reference position (PG) signal of a rotational phase. A magnetized pole 19 (a magnetized pole for position detection) is integrally provided on the axial end face. FIG. 3 shows a deployed state of the rotor magnet 14. As shown in these figures, the position detecting magnetizing pole 19 is provided at the position of the magnetic pole for driving the rotation of the rotor magnet 14 having the same polarity as its magnetizing polarity. ). In other words, if the position detecting magnetizing pole 19 is an S pole, the magnetizing pole 19 is provided in the S pole rotation driving magnetic pole. If the position detecting magnetizing pole 19 is an N pole, the magnetizing pole 19 is provided in the N pole rotation driving magnetic pole.

As shown in FIG. 1, a detection sensor 16 (consisting of a coil) for detecting a position faces the end surface of the rotor magnet 14 on the circuit board 15, and as shown in FIG. The sensor is placed in a hole 17 formed in the circuit board 15, and a lead wire of the sensor is connected to the circuit by soldering 20. Moreover, an axial coil is used as the detection sensor 16, and the coil winding direction (axial direction) is arranged parallel to the end face of the rotor magnet 14.

Next, the operation of the rotational position detecting device configured as described above will be described. The position detecting magnetizing pole 19 is formed by magnetizing the end face of the rotor magnet 14, and as shown in FIG. 5, the position detecting magnetizing pole (S pole in this case) has the same polarity as the rotating rotor magnet. It is provided integrally within the driving magnetic pole (S-pole). With this configuration, a separate magnet for the position detection magnetizing pole is not required, and cost reduction can be achieved. In addition, it was confirmed that the video screen was not adversely affected by jitter and the performance did not deteriorate. Further, since the detection sensor 16 is disposed on the fixed side facing the end face of the rotor magnet 14, the detection sensor 16 can easily detect a change in the magnetic field of the magnetized pole 19 due to the rotation of the rotor magnet 14.

Further, since the detection sensor 16 is an axial coil and the winding direction of the coil is orthogonal to the winding direction of the stator coil 12 forming the core magnetic pole of the stator core 11, the detection sensor is further improved. 16 is less affected by the magnetic field of the core pole 18.

Further, since the detection sensor 16 is fitted and fixed in the hole 17 provided in the circuit board 15, the distance between the circuit board 15 and the end face of the rotor magnet 14 may be reduced. Therefore, the axial dimension of the head motor 2 can be reduced.

The present invention is not limited to the configuration of the above-described embodiment, and various modifications are possible. For example, although the case where the detection sensor 16 is an axial coil has been described above, the present invention is not limited to this type. The sensor may be a radial type sensor.

[0016]

[Effect of the invention]

 As described above, according to the present invention, the end face of the rotor magnet is magnetized to provide the position detecting magnetized pole, so that another magnet is not required and cost can be reduced. In addition, since the position detecting magnetizing pole is provided at the same polarity as the magnetic pole for driving the rotation of the rotor magnet, there is no adverse effect of jitter on the video screen, and performance deterioration is reduced.

[0017] Furthermore, by arranging the detection sensor by fitting it into a hole formed in the circuit board, the distance between the circuit board and the facing surface of the end face of the rotor magnet can be shortened. The size in the axial direction can be reduced.

Further, since the detection sensor is composed of a coil and its axial direction is arranged in parallel with the end face of the rotor magnet, the detection sensor can easily detect a change in the magnetic field of the magnetized pole for detecting the position of the rotor magnet. In addition, since the detection sensor is hardly affected by the magnetic field of the stator coil, the effect of reducing the adverse effect of the jitter is remarkably obtained.

[Brief description of the drawings]

FIG. 1 is a half sectional side view of a cylinder head having a rotary drum motor rotational position detecting device according to an embodiment of the present invention.

FIG. 2 is a perspective view of a rotor magnet of the motor.

FIG. 3 is an expanded view of a rotor magnet of the motor.

FIG. 4A is a plan view from the circuit board side, showing how the detection sensor of the motor is attached to the circuit board;
(B) is sectional drawing of a detection sensor attachment part.

FIG. 5 is a diagram showing a positional relationship between a rotation driving magnetized pole and a position detecting magnetized pole;

[Explanation of symbols]

 2 Head Motor 11 Stator Core 12 Stator Coil 13 Rotor 14 Rotor Magnet (Rotation Drive Magnetization) 15 Circuit Board 16 Detection Sensor (Coil) 19 Magnetization Pole (Position Detection Magnetization Pole)

Claims (3)

[Utility model registration claims] 1. A rotor magnet having a rotation driving magnetic pole, a stator core having a stator coil wound opposite to the rotor magnet, a position detecting magnetized pole provided on the rotor magnet, A rotation sensor for detecting the change in the magnetic field due to the rotation of the rotor magnet with the detection sensor and obtaining a rotation position signal. The position detection magnetized pole is provided so as to face in the circumferential direction, and the position detection magnetized pole is provided at a position of a rotation drive magnetic pole having the same polarity as the magnetized polarity on an end face of the rotor magnet. A rotation position detection device for a rotary drum motor, wherein the rotation position detection device is disposed at a position facing an end face of the rotor magnet. Place. 2. The rotary drum motor according to claim 1, further comprising a circuit board for controlling energization of the stator coil, wherein the detection sensor is fitted in a hole formed in the circuit board. Rotational position detector. 3. The rotational position of the rotary drum motor according to claim 1, wherein the detection sensor comprises a coil, and an axial direction thereof is arranged in parallel with an end face of the rotor magnet. Detection device.