JP2965376B2 - Motor rotation phase detection mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanism for detecting the rotational phase of a motor, and more particularly, to a mechanism suitable for a rotary magnetic head for recording and reproducing information on a magnetic recording medium such as a magnetic tape. The present invention relates to a rotation phase detection mechanism.

[0002]

2. Description of the Related Art Conventionally, a fixed head has been used as a magnetic head for recording / reproducing a magnetic tape such as a compact cassette tape. However, in recent years, VTRs (Video Ta
pe Recorder) tape, DAT (Digital Audio Ta)
In recording and reproducing a tape for a perecorder, a rotating magnetic head has been used to increase the relative recording speed between the tape and the head.

FIG. 5 is a schematic diagram showing an example of the configuration of a conventional rotary magnetic head. This rotary magnetic head is an example of a brushless motor direct connection type rotary head. In FIG.
This rotary magnetic head 100 is roughly divided into magnetic heads H
And a drive motor M for driving the magnetic head H. The drive motor M includes a coil 1, a substrate 4,
And a rotor 3. The rotor 3 includes a driving magnet 2, a signal magnet 13, and a rotor yoke 1.
And 1.

[0006] FIG. 6 is a detailed diagram showing a configuration of a rotation phase detecting mechanism of a conventional rotary magnetic head motor. FIG.
6A is a cross-sectional view, and FIG. 6B is a plan view.
As shown in the figure, the rotor 3 is provided with a rotor yoke 11
And a drive magnet 2 and a signal magnet 13. Further, the Hall element 6 is provided on the substrate 4. As shown in the figure, the Hall element 6 is arranged so as to face the signal magnet 13. Signal magnet 13
Is provided with a magnetized portion 15 for a PG (Pulse Generator), which is detected by the Hall element 6 to generate a PG signal, thereby controlling the rotation phase. That is, the Hall element 6
The signal magnet including the PG magnetized portion 15 and the rotor yoke constitute a rotation phase detection mechanism of the drive motor M.

[0005]

However, as shown in FIG. 7, in the conventional example, since the output level of the PG signal is low, a sufficient threshold level cannot be obtained on the circuit side, and the hysteresis width cannot be increased. Was. For this reason,
This caused a malfunction of the circuit. This PG signal has a temperature characteristic, and its output decreases at high temperatures, which has been a particularly serious problem during high-temperature operation.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a motor rotation phase detecting mechanism capable of outputting a high-level PG signal.

[0007]

According to a first aspect of the present invention, there is provided a rotating body made of a metal constituting a motor, a driving magnet provided on the rotating body, and the rotating body. A motor comprising: a magnetized body provided above and partially magnetized; and a Hall element provided to face the magnetized portion of the rotating magnetized body and detecting a magnetic flux signal for detecting a rotation phase. Wherein the portion of the rotating body corresponding to the magnetized portion is cut out.

According to a second aspect of the present invention, in the rotation phase detecting mechanism for a motor according to the first aspect, the magnetized body has a projection that fits into a notch of the rotating body. You.

[0009]

According to the first aspect of the present invention having the above structure, the portion corresponding to the magnetized portion of the metal rotator provided with the magnetized body is cut out to increase the magnetic resistance of the rotator. Accordingly, the magnetic flux passing through the magnetized body provided on the rotating body is reduced. For this reason, the leakage magnetic flux from the driving magnet penetrating the Hall element increases. Therefore, the magnetic flux from the magnetized portion of the magnetized body and the leakage magnetic flux from the driving magnet are combined, and the level of the magnetic flux signal detected by the Hall element increases. As a result, a sufficient threshold level and hysteresis width can be obtained.

Further, according to the second aspect of the present invention, by providing a projection such that the magnetized body fits into the notch of the rotating body, the magnetization of the magnetized portion is made based on the projection. In addition, since the driving magnet can be magnetized with reference to the notch of the rotating body, a special positioning method or the like is not required.

[0011]

Next, a preferred embodiment of the present invention will be described with reference to the drawings. First Embodiment FIG. 1 shows the configuration of a first embodiment of the present invention. FIG. 1A is a sectional view, and FIG. 1B is a plan view. FIG.
1 shows an example in which the present invention is disclosed for a rotation phase detection mechanism of a motor. As shown in the figure, 3A indicates a rotor,
The rotor 3A includes a rotor yoke 11A, a driving magnet 2, and a signal magnet 13. Reference numeral 6 denotes a Hall element, and the Hall element 6 is provided on the substrate 4.

As shown in FIG. 1B, the rotor yoke 1
1A is made of a metal such as a galvanized steel plate and has a disk shape. The drive magnet 2 has a ring shape and is alternately magnetized to the N pole and the S pole equally in several parts. Signal magnet 13
Is ring-shaped, and a part 15 is magnetized to the N pole.
Further, a portion 8 of the rotor yoke 11A corresponding to the magnetized portion 15 is notched as shown in the figure. Here, the rotor yoke 11A corresponds to a metal rotating body, the drive magnet 2 corresponds to a drive magnet, and the signal magnet 13 corresponds to a magnetized body.

Next, the operation of the first embodiment will be described with reference to FIG. FIG. 3 is a diagram showing the operation of the conventional motor rotation phase detecting mechanism and the embodiment of the present invention.
FIG. 3B is a magnetic force diagram in the case of the conventional example, and FIG.
FIG. 4 is a magnetic force line diagram of the example. Arrow lines indicate lines of magnetic force. Further, among the reference numerals of the respective parts, the same reference numerals as those in FIG. 1 or FIG. 6 represent the same parts. A portion not shown in FIG. 1 or FIG. 6 includes a coil 1 provided on a surface of the FG / PG detection substrate 4 opposite to the Hall element, and the coil 1 provided with the FG / PG.
The stator yoke 17 is provided so as to sandwich the detection substrates 4 therebetween.

As shown in FIG. 1A, in the case of the conventional example, the magnetic flux from the drive magnet 2 passes through the Hall element, returns to the drive magnet 2 via the signal magnet 13 and the rotor yoke 11, and returns. Therefore, the signal magnet 1
Since the magnetic flux from the N pole magnetized portion 15 of No. 3 is partially obstructed,
The level of the PG signal detected by the Hall element 6 decreases. On the other hand, as shown in FIG. 1B, in the case of the first embodiment of the present invention, the rotor yoke 11
A portion 8 of A is cut out, so that the magnetic resistance of the rotor yoke 11A in the cutout portion 8 is increased.
As shown in (B), the magnetic flux penetrating the signal magnet 13 decreases. As a result, on the contrary, the leakage flux from the drive magnet 2 through the Hall element 6 increases. Therefore, since the leakage magnetic flux is combined with the magnetic flux of the magnetized portion 15 magnetized to the N pole, the PG signal level detected by the Hall element increases. FIG. 4 shows the level of the PG signal in this case.

Second Embodiment FIG. 2 shows the configuration of a second embodiment of the present invention. FIG. 2 is a diagram showing only the vicinity of the magnetized portion 15. The difference between the second embodiment and the first embodiment is that the signal magnet 13B is provided with a projection 18 in the notch 8 so as to be fitted to the rotor yoke 11B. With this configuration, the magnetized portion 15 can be
And the drive magnet 2 can be magnetized with reference to the notch 8 of the rotor yoke 11B. This eliminates the need for a special magnet positioning method or the like. Also, the assembly of the rotor yoke 11B and the signal magnet 13B is facilitated.

In the above embodiment, the drive magnet 2 is magnetized as shown in FIG. 1, and the magnetized portion 15 is magnetized to the N pole. However, the order may be reversed. That is, the magnetization of the drive magnet is reversed from that in FIG.
5 may be magnetized to the S pole.

[0017]

As described above, according to the present invention,
It can output a high-level PG signal, and does not require special positioning for magnetization, and has advantages such as easy assembly of the magnet.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 3 is a diagram showing an embodiment of the present invention and a conventional operation.
FIG. 3A is a magnetic field diagram of the conventional example, and FIG. 3B is a magnetic field diagram of the first embodiment of the present invention.

FIG. 4 is a diagram showing an output of a PG signal in the embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a conventional rotary magnetic head.

FIG. 6 is a schematic diagram showing a configuration of a rotation phase detection mechanism of a motor of a conventional rotary magnetic head.

FIG. 7 is a diagram showing an output of a PG signal in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Coil 2 ... Driving magnet 3, 3A, 3B ... Rotor 4 ... Substrate 6 ... Hall element 8 ... Notch part 11, 11A, 11B ... Rotor yoke 13, 13B ... Signal magnet 15 ... Magnetization part 17 ... Stator yoke 18 ... Convex part H ... Magnetic head M ... Drive motor

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H02K 29/00 H02K 1/27 503 H02K 1/30 H02K 11/00 H02K 21/00

Claims (2)

(57) [Claims] 1. A rotating body made of metal constituting a motor, a driving magnet provided on the rotating body, a magnetized body provided on the rotating body and a part of which is magnetized, A Hall element provided to face the magnetized portion of the magnetized body and detecting a magnetic flux signal for detecting a rotational phase, comprising: a rotation phase detection mechanism for a motor, the rotating body corresponding to the magnetized portion. A motor rotation phase detection mechanism characterized in that a part of the motor is notched. 2. The rotation phase detecting mechanism for a motor according to claim 1, wherein the magnetized body has a convex portion that fits into a notch of the rotating body. Motor rotation phase detection mechanism.