JP3071958U - Rotary drum motor rotation position detector - Google Patents

Abstract

(57) Abstract: In a rotation position detection device for a rotary drum motor, switching noise in a rotation position signal can be reduced, and the occurrence probability of an erroneous rotation position signal is reduced. SOLUTION: A magnetized pole for position detection is set to a rotor magnet 1.
4, the detection sensor 16 is disposed at a position facing the 14 end surface of the rotor magnet and facing the core magnetic pole in the circumferential direction of the stator core 11. The detection sensor 16 easily detects a change in the magnetic field of the magnetized pole, and is less likely to be affected by the magnetic pole of the stator core 11.
Switching noise is reduced, and the probability of occurrence of an erroneous rotation position signal is reduced.

Description

[Detailed description of the invention]

[0001]

[Technical field to which the invention belongs]

 The present invention relates to a rotation position detection device of a rotation drum motor which is applied to a rotation head cylinder or the like of a magnetic recording / reproduction device and detects a change in a magnetic field due to rotation of a rotor magnet with a detection sensor to obtain a rotation position signal.

[0002]

[Prior art]

 Conventionally, this type of rotary drum motor rotation position detection device uses a position detection magnetizing pole provided on a rotor magnet of the rotary drum motor and a detection sensor coil provided on a fixed side for position detection. It is generally known that a change in a magnetic field due to rotation of a rotor magnet is detected by a sensor coil to detect a rotation position and one pulse (PG pulse) is output for one rotation of a rotary drum motor (for example, JP-A-2-179913, JP-B-6-19295, etc.).

Here, a conventional rotation position detection device for a rotary drum motor will be described with reference to FIGS. 6 and 7. FIG. The rotary drum motor has a stator core 11 and a rotatable rotor magnet 14 facing the outer periphery thereof. The stator core 11 has a plurality of magnetic poles 18 around which a stator coil 12 is wound. Is provided with one magnet (not shown) for detecting the rotational position, and is provided with a sensor 16 ′ such as a hall element for detecting the rotational position on the fixed side. The change in the magnetic field of the magnet is detected by the sensor 16 '. When the sensor 16 'is a Hall element, it is considered that the magnetic field between the magnetic poles 18 (between the throttles) of the stator core 11 is unlikely to be affected by the magnetic field, and thus the sensor 16' is arranged between the magnetic poles 18 (between the throttles).

FIG. 7 shows a rotation position signal PG-A (PG linear amplifier output) obtained from a sensor 16 ′ in the above-described rotation position detection device and a frequency signal FG-P (FG pulse output) from a sensor (not shown). The measurement results are shown. The rotation position signal PG-A (PG linear amplifier output) changes in a wave-like manner with the rotation of the rotor magnet 14, and the power supply to the stator coil 12 corresponding to the frequency signal FG-P (FG pulse output). Under the influence of switching, whisker-like noise is added. From the rotation position signal PG-A (PG linear amplifier output), one rotation position signal PG-P (PG pulse output) is acquired for each rotation by the magnet of the rotor magnet 14. For this purpose, as shown in FIG. 8, a point where the rotational position signal PG-A (PG linear amplifier output) exceeds a predetermined threshold value is set as a slice point, and the rotational position signal PG-P is obtained at that timing. ing.

[0005]

[Problems to be solved by the invention]

 However, in the conventional configuration, as shown in FIG. 7, the rotational position signal PG-A (PG linear amplifier output) is affected by the switching, and relatively large beard-like noise (switching noise) is generated. Since the peaks are superimposed, the margin between the peak and the slice point is small. Therefore, when the noise falls below the slice point and the margin becomes zero, the probability that an erroneous rotation position signal (pseudo PG pulse) is generated there increases, and there is a possibility that a number of pseudo PG pulses are generated in one rotation. there were.

The present invention solves the above-mentioned conventional problem, and can reduce the switching noise in the rotation position signal and increase the margin with the slice point for obtaining the rotation position signal. It is an object of the present invention to provide a rotational drum motor rotational position detecting device capable of reducing the probability of occurrence of an erroneous rotational position signal.

[0007]

[Means for Solving the Problems]

 In order to achieve the above object, the invention of claim 1 comprises a rotor magnet, a stator core on which a stator coil is wound facing the rotor magnet, and a position detecting magnetizing pole provided on the rotor magnet. A rotation sensor for detecting the position of the rotating magnet, wherein the detection sensor detects a change in magnetic field due to rotation of the rotor magnet, and obtains a rotation position signal. Is provided on the end face of the rotor magnet, and the detection sensor is arranged at a position facing the end face of the rotor magnet and facing one core magnetic pole in the circumferential direction of the stator core.

In the above configuration, it is sufficient to provide a magnetized pole for position detection by magnetizing the end face of the rotor magnet, and since the detection sensor is disposed on the fixed side facing the end face of the rotor magnet, It is easy to detect the change in the magnetic field of the position detection magnetized poles, and the position (center of the throttle) facing the core magnetic pole in the circumferential direction of the stator core where the detection sensor is located is smaller than that between the magnetic poles (between the throttles). Since the position is hardly affected by the magnetic pole, switching noise applied to the detection sensor can be reduced, and therefore, the occurrence probability of the erroneous rotation position signal (pseudo PG pulse) is reduced.

In the above, it is preferable that the detection sensor is composed of a coil, and is arranged so that the winding direction is orthogonal to the winding direction of the stator coil of the stator core. As a result, the detection sensor coil is hardly affected by the magnetic field of the stator coil, and the above-described operation can be reliably obtained.

Furthermore, in the above, the detection sensor may be fitted and disposed in a hole formed in the circuit board. Accordingly, in a configuration in which the detection sensor is disposed on the fixed-side circuit board, the distance between the circuit board and the end surface of the rotor magnet can be reduced, and the axial dimension of the rotary drum motor can be reduced.

[0011]

[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, a fixed head 4, and a fixed support shaft 5. The head motor 2 includes a stator core 11 having a plurality of core magnetic poles on which a stator coil 12 is wound, a rotatable rotor 13 having a rotor magnet 14 provided on an outer periphery thereof, and a fixed to the stator core 11. And a circuit board 15 formed. The rotating head 3 is driven to rotate by a rotor 13.

As shown in FIG. 2, the rotor magnet 14 has a plurality of N and S magnetic poles formed on a circumference, and further has a magnetized pole 19 (position-detected magnetized pole) serving as a reference position of the rotational phase. It is provided on the end face in the direction. On the circuit board 15, a detection sensor 16 (made of a coil) for position detection faces the end face of the rotor magnet 14, and is formed on the fixed-side circuit board 15 as shown in FIG. The sensor leads are fitted into the holes 17 and the sensor leads are connected to the circuit by soldering 20.

As shown in FIG. 4, the detection sensor 16 is disposed at a position (center of the throttle destination) facing one core magnetic pole 18 in the circumferential direction of the stator core 11. The coil winding direction of the detection sensor 16 is arranged so as to be orthogonal to the winding direction of the stator coil 12 of the stator core 11 (see FIG. 4).

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 the detecting sensor 16 is disposed on the fixed side facing the end face of the rotor magnet 14. A change in the magnetic field of the magnetized pole 19 due to the rotation of the magnet 14 can be easily detected. At the same time, when the detection sensor 16 is a coil, the position (throttle destination center) facing one core magnetic pole 18 in the circumferential direction of the stator core 11 where the sensor is disposed is determined by the magnetic poles as compared with the magnetic poles (between the throttles). Since the position is hardly affected, the switching noise applied to the detection sensor 16 is reduced.

FIG. 5 shows this state. As can be seen by comparing FIG. 7 with FIG. 7 described above, the rotational position signal PG-A (the output of the PG linear amplifier) is less affected by the switching, and has a relatively small whisker-like noise ( Switching noise), and the margin between the peak and the slice point increases. For this reason, the margin increases, and the probability that an erroneous rotation position signal (pseudo PG pulse) is generated is reduced. Therefore, the rotation position signal can be obtained with high accuracy.

Further, since the winding direction of the coil of the detection sensor 16 is orthogonal to the winding direction of the stator coil 12 forming the core magnetic pole 18 of the stator core 11, the detection sensor 16 further increases the magnetic field of the core magnetic pole 18. Less likely to be affected by

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 and the end surface of the rotor magnet 14 can 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, in the above description, the embodiment in which the rotor magnet 14 is opposed to the outer peripheral surface of the stator core 11 is shown. A configuration in which the stator core 11 and the rotor magnet 14 face each other in the axial direction may be used.

[0019]

[Effect of the invention]

 As described above, according to the present invention, the detection sensor is easy to detect a change in the magnetic field of the magnetized pole for detecting the position of the rotor magnet and is hardly affected by the magnetic pole of the stator core. Noise is reduced, and an accurate rotation position detection signal is obtained.

Further, since the detection sensor is composed of a coil and is arranged so that the winding direction thereof is orthogonal to the winding direction of the stator coil of the stator core, the detection sensor coil is hardly affected by the magnetic field of the stator coil. The effect is surely obtained.

[0021] Furthermore, by arranging the detection sensor in a hole formed in the wiring board, the distance between the wiring board and the end surface of the rotor magnet can be shortened. The size in the axial direction can be reduced.

[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 plan view of a rotor magnet of the motor.

FIG. 3 is a cross-sectional view showing how the detection sensor of the motor is mounted on a circuit board.

FIG. 4 is a plan view showing an arrangement of detection sensors of the motor.

FIG. 5 is a diagram showing a detection signal waveform of the detection sensor.

FIG. 6 is a plan view showing an arrangement of a detection sensor of a conventional rotary drum motor.

FIG. 7 is a diagram showing a detection signal waveform by a conventional detection sensor.

FIG. 8 is a partially enlarged view of FIG. 7;

[Explanation of symbols]

 2 Head motor 11 Stator core 12 Stator coil 13 Rotor 14 Rotor magnet 15 Circuit board 16 Detection sensor (coil) 19 Magnetized pole (Positioned magnetized pole)

Claims (3)

[Utility model registration claims] A rotor core, a stator core having a stator coil wound around the rotor magnet, a position detecting magnetized pole provided on the rotor magnet, and a position sensor for position detection. In the rotation position detection device for a rotary drum motor, which detects a magnetic field change due to rotation of the rotor magnet with the detection sensor and obtains a rotation position signal, the position detection magnetization pole is provided on an end surface of the rotor magnet, and the detection sensor is 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 and facing one core magnetic pole in a circumferential direction of the stator core. 2. The rotational position detecting device for a rotary drum motor according to claim 1, wherein said detecting sensor is composed of a coil, and a winding direction thereof is arranged to be orthogonal to a winding direction of a stator coil of the stator core. . 3. The rotation position detection device for a rotary drum motor according to claim 2, wherein said detection sensor is fitted and arranged in a hole formed in a circuit board.