JPS60206115A - Magnetizing device for magnet used for rotary detecting device - Google Patents

Abstract

PURPOSE:To facilitate multipolarization of magnetized pole number by a method wherein a magnetizing part to be used for detection of rotating speed is formed on the material to be magnetized based on the signal obtained at a detection head following the rotation of the reference gear, a part of the tooth section of the reference gear is cut away, and a non-magnetizing part ao be used for detection of rotating phase is formed at a part of the material to be magnetized. CONSTITUTION:When the body 7 to be magnetized and the reference gear 11 are integrally rotated, an irregular rotation can be reduced, because a flywheel 3 is provided on a rotating shaft 2. As magnetic bias is given to the reference gear 11 by a permanent magnet 13, an AC signal of a cycle is outputted to a detection head for every formation pitch B of a gear 12 with the tooth part 12 crossing the front of a detection head 14 following the rotation of the reference gear 11. As said signal is amplified by an amplifier 16 and a magnetizing head is excited, the body to be magnetized which performs a face-to-face rotation is magnetized at two magnetic poles N and S for every formation pitch B of the tooth part 12, and a magnetizing part 8 to be used for detection of rotational speed is formed. Also, when the part where the tooth part 12 is cut away is opposed to the detection head 14, the magnetizing head 15 is not excited, and a non-magnetized part 9 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a magnetizing device for a magnet for a rotation detection device that detects rotation speed and rotation phase.

[Technical background of the invention]

For example, a Schilling motor for a video tape recorder is provided with a rotation detection device that detects the rotational speed and rotational phase of the rotor in order to perform both speed control and phase control. This rotation detection device has a structure in which an annular magnet magnetized in a predetermined pattern is attached to the rotor, and a frequency power generation coil is provided on the stator side in correspondence with the magnet. Japanese Patent Publication No. 58-118055
It is shown in the publication No. In other words, the magnets provided on the rotor have a large number of magnetic poles that are alternately different in the circumferential direction, and a magnetized part for phase detection is formed by setting the pitch of some of the magnetic poles to half of the other half. There is.

The magnetizing device for magnetizing the magnet is composed of an annular magnetizing yoke having slots corresponding to the magnetizing pattern, and a winding wound around each slot of the magnetizing yoke. The object was magnetized by energizing the windings with the object to be magnetized facing the magnetizing yoke.

[Problems with background technology]

However, in the above-mentioned magnetizing device, since slots corresponding to the magnetizing pattern must be formed in the magnetizing yoke, when the number of celadon poles is large, the slot spacing becomes minute and the manufacturability of the magnetizing yoke deteriorates. .

Therefore, there is a limit to increasing the frequency of the rotational speed signal by increasing the number of magnetized poles, and the need for improved controllability of the motor cannot be satisfactorily met.

Moreover, since the magnetic pole pitch of the magnetized part for phase detection of the magnet is half that of the other part, there is a drawback that it is impossible to increase the number of poles of magnetization in other parts due to manufacturing limitations of the magnetizing yoke corresponding to that part. there were.

[Purpose of the invention]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a magnetizing device for a magnet for a rotation detecting device, which can easily increase the number of magnetized poles without deteriorating the manufacturability.

[Summary of the invention]

The present invention rotates a magnetized body and a reference gear synchronously, and provides a celadon head and a detection head corresponding to the magnetized body and the reference gear, respectively, and rotates the detection head as the reference gear rotates. The magnetized head is excited by the obtained signal to form a magnetized portion for rotational speed detection on the magnetized body, and a part of the tooth portion of the reference gear is substantially set in relation to the detection head. By forming a non-magnetized part for detecting the rotational phase in a part of the magnetized body, the conventional magnetized yoke in which slots are formed at minute intervals can be made unnecessary. Has characteristics.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

First, in Figures 1 to 3, 1 is the base, 2 is the base 1
A rotary shaft 3 is rotatably supported on the rotary shaft 2, and a flywheel 3 is fixed to the rotary shaft 2.

A motor 4 is provided on the base 1 apart from the rotating shaft 2. A belt 5 is stretched between the pulley 4a of the motor 4 and the flywheel 3, and the motor 4 moves the rotating shaft 2 at a constant speed. It is designed to be rotatably driven. Reference numeral 6 denotes a rotor (rotating body) detachably attached to the upper part of the rotating shaft 2, which constitutes a cylinder motor to be described later, and has an annular celadon magnet 7 provided at its lower end. This magnetized body 7 is magnetized as described later to form a celadon part 8 for rotational speed detection and a non-magnetized part 9 for rotational phase detection, thereby detecting the rotation of the rotor 6 assembled as a cylinder motor. This is a magnet 10 for a device. As shown in FIG. 2, the magnetized section 8 for detecting rotational speed is composed of a large number of magnetic poles that are alternately different in the circumferential direction and are magnetized at an equal magnetic pole pitch A. on the other hand,
Reference numeral 11 denotes a reference gear made of a magnetic material attached to the lower end of the rotary shaft 2, which is rotated in synchronization with the rotor 6 on the upper part of the rotary shaft 2 and the celadon magnet 7 by rotating the motor 4. A large number of teeth 12 are provided protruding from the outer periphery of the reference gear 11 (see FIG. 3).

The pitch B between the teeth 12 is set to twice the magnetic pole pitch A in the magnetized portion 8 of the magnet 11, and one of the teeth 12 is missing. A permanent magnet 13 is placed over the reference gear 11, and is magnetized on both the upper and lower sides to apply a magnetic bias to the reference gear 11. 14 is a detection head facing the reference gear 11 on the outer peripheral side;
5 is a magnetic head facing the magnetized body 7 from below;
The detection head 14 is connected to the magnetizing head 15 via an amplifier 16 and a current limiting resistor 17.

In the magnetizing device having the above configuration, when the motor 4 is driven,
The magnetized body 7 and the reference gear 11 rotate integrally. At this time, since the rotary shaft 2 is provided with the flywheel 3, rotational unevenness can be extremely reduced. Since the reference gear 11 is given a magnetic bias by the permanent magnet 13, the teeth 12 of the reference gear 11 rotate as the reference gear 11 rotates.
The detection head 1 crosses the front surface of the detection head 14.
4, one period of an alternating current signal is outputted every pitch day for forming the tooth portion 12. This signal is amplified by the amplifier 16 and excites the magnetizing head 15, so that the magnetized body 7, which rotates opposite to the magnetic head 15, is attached to two magnetic poles of N-8 every pitch day when the teeth 12 are formed. As a result, a stone magnet portion 8 for detecting rotational speed as shown in FIG. 2 is formed. Further, when the portion of the reference gear 11 where the tooth portion 12 is missing faces the detection head 14, no signal is output to the detection head 14, so the magnetization head 15 is not excited and the non-magnetized portion 9 is formed. be done.

Next, an example in which the magnet 10 produced by the magnetizing device described above is used in a cylinder motor of a video cheap recorder will be described with reference to FIGS. 4 to 7. 18 is a cylinder that integrally has a bearing sleeve 18a, and 19 is a cylinder 18 of the bearing sleeve 18a.
This stator 19 is fitted into the downwardly projecting portion of the stator core 20 and includes a plurality of armature coils 21.
It is made by wrapping. A rotor shaft 22 is rotatably supported by a bearing cylinder 18a, and a rotor shaft 24 having a video head 23 located inside the cylinder 18 is fixed to the upper end of the rotor shaft, and a rotor shaft 24 that surrounds the stator 19 is attached to the lower end of the rotor shaft. The rotor 6 is fixedly attached. The rotor 6 is provided with another field magnet 25 of the magnet 10 described above so as to form a gap in the radial direction with respect to the stator 19. 26 is a printed circuit board attached to the lower surface of the cylinder 18, and 27 is a position detection element provided on the lower surface of this printed circuit board 26, which detects the rotational position of the rotor 6 and controls the armature coil 21 according to the rotational position. By sequentially energizing the rotor 6, the video head 23 is rotated. Reference numeral 28 denotes a shield plate provided on the lower surface of the cylinder 18, which is made of permalloy, for example, and is used to shield radiation noise caused by switching of the armature coil 21. On the lower surface of the printed circuit board 26, in an annular region facing the magnet 10 of the rotor 6, there is provided a frequency generating coil 29, which together with the magnet 10 constitutes a rotation detection device for detecting the rotational speed and rotational phase of the rotor 6. is forming.

As shown in FIG. 5, these two frequency generating coils have a rainbow shape in which rectangular waves are continuous in an annular shape, and the pitch C for one period is the magnetic pole pitch A of the magnet 10 @magnetic part 8.
-C is set to twice the value of -C. Further, a pair of eyeliner portions 29a and 29b are provided at both ends of the frequency power generation coil 29, and a tap 29C is provided at a location half a pitch away from one of the output wheels 11 portion 29b. A phase detection section 30 is provided between the output line section 29b and the output line section 29b. FIG. 6 shows the configuration of an electric circuit for processing the signal obtained by the frequency generating coil 29, where 31 and 32 are amplifiers, and 33 is a comparator.

Now, in the cylinder motor configured as above, when the rotor 6 rotates, the magnetized portion 8 of the magnet 10 moves relative to the frequency generation coil 29.
A rotational speed signal S having a frequency corresponding to the rotational speed of the rotor 6 as shown in FIG.
1 is obtained.

This rotational speed signal S1 is amplified by an amplifier 31, and the speed of the rotor 6 is controlled based on this signal. Meanwhile, at the same time, the phase detection section 30 of the frequency power generation coil 29 has the seventh
A phase detection signal S2 as shown in Figure (b) is output. This phase detection signal S2 is sent to the phase detection section 30 by the magnet 1.
During the period when the magnetized part 8 of 0 is facing, the frequency signal is a constant amplitude frequency signal synchronized with the rotational speed signal S1 described above, but when the non-magnetized part 9 of the magnet 10 is facing the phase detection part 30, the amplitude is sharply decrease. Therefore, if this phase detection signal S2 is amplified to a predetermined amplitude by the amplifier 32 and compared with the rotation speed signal S1 amplified by the amplifier 31 by the comparator 33, the rotation as shown in FIG. 7(C) is obtained. A phase signal S3 is obtained. This rotational phase signal S3 is transmitted to the non-magnetized portion 9 of the magnet 10.
is a high-level pulse signal that faces the phase detection section 30 of the frequency generating coil 29, and is therefore synchronized with the rotational phase of the rotor 6. Based on this, the rotor 6
phase control is performed.

According to the present embodiment described above, when magnetizing the magnet 10, first the reference gear 11 having the teeth 12 corresponding to the @magnetic pattern is manufactured in place of the conventional magnetizing yoke. However, since the magnetizing yoke directly magnetizes the object to be magnetized, it is limited to one having approximately the same diameter as the object to be magnetized. On the other hand, the 14 dimensions of the reference gear 11 of the present invention can be determined independently of the magnetized body 7. Therefore, by making the reference gear 11 large in diameter, it is possible to increase the number of magnetized poles without imposing any restrictions on the machining accuracy when cutting the tooth portion 12.

With this, the controllability of the rotational speed and rotational phase of the cylinder motor can be greatly improved. In addition, conventionally, the phase detection magnetized part is formed by locally magnetizing with a finer pitch of magnetic poles than the other parts, and the phase detection part is used to detect the rotational phase of the rotor. There is a problem in that multipolarization in other parts is also restricted due to limitations in cutting the slot in the part corresponding to the magnetized part for detection. Regarding this point, in this embodiment, since the non-magnetized portion 9 is formed in the magnet 10 in order to detect the rotational phase, sufficient multipolarization can be achieved. Moreover, the non-magnetized portion 9 can be easily formed by using a reference gear 11 with some of the teeth 12 removed. Such reference gear 11
may be manufactured by cutting off some of the teeth from a gear with teeth formed all around the circumference in advance, or by forming a notch in advance on the material disk for the reference gear 11, and then, for example, forming a bob. The southern part may be formed by cutting with a disk, and in either case, it can be manufactured very easily. Furthermore, magnet 1
Since each magnetic pole of 0 is sequentially magnetized without rotating the magnetized body 7, the current capacity of the magnetizing power source is significantly reduced compared to a conventional device that magnetizes all magnetic poles at the same time. can do.

In the above embodiment, some of the tooth portions 12 are used as the M semi-gear 11.
However, the present invention is not necessarily limited to this, and it is possible to use a reference gear with a southern part formed around the entire circumference, and attach, for example, amorphous metal foil to some of the teeth. It is also possible to provide magnetic shielding between the toothed portion and the detection head, in other words, it is sufficient to substantially omit a portion of the tooth portion in relation to the detection head.

〔Effect of the invention〕

As described above, the present invention rotates a magnetized body and a reference gear synchronously, and provides a magnetizing head and a detection head corresponding to the magnetized body and the reference gear, respectively, and rotates the reference gear. Accordingly, the magnetizing head is excited based on a signal obtained from the detection head to form a magnetized portion for rotational speed detection on the magnetized body, and a part of the tooth portion of the reference gear is subjected to the detection 8i. This is characterized in that a non-magnetized portion for rotational phase detection is formed in a part of the magnetized body by substantially missing it in relation to the head. This greatly improves manufacturability compared to conventional magnetizing devices, which require forming a large number of slots at minute intervals and winding the slots. Since it can be determined independently of that of the magnetic body, by setting the reference gear large, it is possible to increase the number of magnetized poles without being subject to machining restrictions. Furthermore, since each magnetic pole is sequentially magnetized, a small-capacity power source for magnetization can be used, thereby reducing the cost of the device.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, in which Fig. 1 is a schematic configuration diagram of the entire magnetizing device, Fig. 2 is a plan view not showing the magnetization pattern of the magnet, and Fig. 3 is a flat diagram of the reference gear. 4 is a vertical sectional view of the cylinder motor, FIG. 5 is a plan view of the printed circuit board, FIG. 6 is a block diagram, and FIG. 7 is a voltage waveform diagram. In the drawing, 6 is a rotor (rotating body), 7 is an electrified object, 8 is a magnetized part for detecting rotational speed, 9 is a non-magnetized part for detecting rotational phase, 11 is a reference gear, and 14 is a detection head. , 15 is a magnetizing head. Applicant Tokyo Shibaura Electric Co., Ltd. No. 1 Figure 6 2 Figure 31 Atsushi 4 Figure 5 Review

Claims (1)

[Claims] 1. A device for magnetizing a magnet for a rotation detection device installed on a rotating body to detect the rotational speed and rotational phase of the rotating body, which rotates the magnetized body and a reference gear in synchronization. , a magnetizing head and a detection head are provided corresponding to the magnetized body and the reference gear, respectively, and the magnetizing head is excited based on a signal obtained from the detection head as the reference gear rotates to magnetize the magnetized body. A magnetized portion for rotational speed detection is formed in the magnetized body, and a portion of the tooth portion of the reference gear is substantially missing in relation to the detection head, so that a portion of the magnetized body is formed for rotational phase detection. 1. A magnetizing device for a magnet for a rotation detection device, characterized in that a non-magnetized portion is formed.