JPH0442073A - Reference position detector for magnetic head - Google Patents

Abstract

PURPOSE:To automatically position a reference position and to accurately set by passing a magnetic head between knife edges of a high magnetic flux density generator, and obtaining a maximum sensitivity part obtained by the head as the reference position. CONSTITUTION:A high magnetic flux density generator 11 has metal plates 16a, 16b of a magnetic material and a magnet 17 interposed to be held between the plates 16a and 16b. A delicate gap between knife edges 14 for obtaining a bent and condensed magnetic flux is formed of the ends of the plates 16a, 16b. A magnetic force head 10 passing between the edges 14 is secured to the end of a magnetic flux density measuring unit 38 by a holder 50 to be telescoped on the horizontal surface of a slide base 48 sliding vertically. A stepping motor 40 mounted on the base 48 is driven to move the head 10 in an axial direction, and a maximum sensitivity part to become reference position is detected by passing the head 10 between the edges 14. Simultaneously, the reference position is obtained by the number of pulses sent from the motor 40. Thus, the reference position is automatically positioned, and can be accurately set.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a reference position detection device for a magnetic head, and is particularly used for precisely measuring the magnetization distribution of a magnetization rotor used in a brushless motor. The present invention relates to a reference position detection device for a magnetic head that can automatically detect and set the reference position of a magnetic head.

"Prior Art" In recent years, with the rapid development of audio equipment, video equipment, computers, etc., there is a growing demand for higher quality as their performance improves.

In particular, motors installed in AVII equipment (audio visual equipment) are required to have small rotational irregularities, high efficiency, and stability.

However, as for the drive method, the direct drive method has started to attract attention, and a motor with low speed and extremely small rotational irregularity is required, and the axial flux brushless motor is the best motor to satisfy this requirement, and the AVi
This motor is commonly used in devices.

In other words, as shown in the overall cross-sectional views of brushless motors in FIGS. 5(a) and 5(b), the most commonly used three-phase bipolar 8-pole brushless motor has an outer diameter with a small axial dimension compared to its diameter. It has a flat configuration.

In this case, the rotor 60 is formed of a disk-shaped magnet, and has a ``:i1 magnetic configuration called axial flux, which is magnetized in the direction of a rotation axis 62a perpendicular to the surface of the disk.

One of the rotating shafts 62a of the rotor magnet 62 is connected to a bearing 6 inserted into the boss 65a of the housing 65.
It is rotatably supported via 7a and 67b.

Further, an iron substrate (hereinafter referred to as a yoke 98) is fixed to the upper surface of a flange 65b formed on the housing 65, and six fan-shaped coils 96 are arranged in the shape of orange slices on the upper surface of the yoke 98, which becomes an insulating surface 98a. A stator 97 is configured. The lower surface of the rotor magnet 62 is magnetized into an 8-pole fan shape, and there is a slight gap δ between this magnetized surface 62b and the upper surface of the coil 96 of the stator 97.
The rotor magnet 62 is supported so as to form.

Further, the coil 96 has a positional relationship of ±7.5° based on the position where the magnetic pole and the center of the coil 96 overlap.
The torque-generating conductor (straight portion) of the coil overlaps a lot with the magnetic pole boundary, making the torque generated by the coil unstable, so it is disconnected from the motor circuit.

On the other hand, for the six coils 96, two coils 96 facing each other around the rotating shaft 62a are connected in series, and two phases that do not meet the above conditions are connected in series, and the magnetic poles ( The direction of the current is controlled so that rotational torque is generated in one direction depending on the north pole and south pole.

In this type of motor, the coil of one phase out of the three phases is always at rest, and this switching is performed by the driver IC every time the rotor 62 rotates 15 degrees.

In other words, torque is generated by each coil simultaneously acting on all magnetic poles of the rotor magnet, and as the rotor magnet rotates, the armature current flows from the coil forming one pole to the next. The coils forming the poles are sequentially switched, each coil is responsible for generating torque in turn, and the coil current of one pole is switched between positive and negative directions depending on the polarity of the approaching magnetic pole, and this current Switching between positive and negative is performed at a synchronous frequency determined by the number of poles of the rotor magnet and the rotational speed of the motor.

In this case, the torque varies depending not only on the strength of the main magnetic flux and the current in the coil, but also on the relative positional relationship between the N pole and the coil 96. In response to changes in the relationship, the current in each coil must be appropriately controlled so that the torque generated at any moment remains constant.

Then, when the torque changes depending on the positional relationship of the rotor magnet 62, the rotational speed of the motor changes instantaneously.
This causes so-called wow and flutter. Since this wow and flutter is fatal to AV motors, it is necessary to suppress torque fluctuations as much as possible.

This control is performed by the Hall element 100 and the coil current control circuit.
Based on the signal, electronic circuitry distributes the appropriate current to the coils of each phase.

Here, in order for the torque generation sequence to be performed accurately, the arrangement positions of the magnetic poles and Hall elements 100 must be accurate. This disturbs the periodicity of the sequence for controlling the coil current, causing the torque to fluctuate over time within one revolution of the motor.

Further, as the rotor magnet rotates, the magnetic poles that generate torque change sequentially, but if there is any unevenness in the magnetization of the magnet, this can immediately cause fluctuations in the rotational speed.

Therefore, it is necessary to measure the magnetization distribution state of the rotor magnets of various brushless motors in advance and collect data on magnetic flux density.

In this case, the most sensitive part of the magnetic head used to measure the magnetization distribution state of the magnetic rotor is marked in advance, and the marking position of the magnetic head is manually positioned at a predetermined position by visual inspection etc. when measuring the magnetic rotor. It was set.

[The invention attempts to solve: & problems] In this way, the task of setting the reference position of the detected magnetic head to a predetermined position is manually operated, which takes a lot of time and reduces the positioning accuracy. It had a set point.

Therefore, an object of the present invention is to determine the highest sensitivity part obtained by passing a magnetic head between the knives of a high magnetic flux density generator as a reference position, and to automatically position this reference position and set it with high accuracy. An object of the present invention is to provide a reference position detection device for a magnetic head.

[Means for Solving the Problems] In order to achieve the above-mentioned objective, the characteristics of the magnetization distribution are detected by moving a magnet rotor in the radial direction, in which both ends of a central shaft are rotatably held between a pair of upper and lower support shafts. In the magnetic head reference position detection device of the present invention, the pair of support shafts, a high magnetic flux density generating device held between the pair of supporting shafts, and a flat plate that moves forward and backward with respect to the high magnetic flux density generating device are provided. The pair of support shafts include a main shaft that is rotatably supported on the base and has a locking part at the tip, and a shaft that is rotatable and slidable in the axial direction on the axis of the main shaft. The high magnetic flux density generator is composed of an auxiliary shaft that is supported and has a locking part facing the main shaft at its tip, and a support provided on the base to support the auxiliary shaft. A pair of metal plates each bent to form a knife are arranged parallel to each other so as to face each other with a predetermined distance apart, and a magnet is sandwiched between the pair of metal plates and is supported through the metal plates. It is composed of a locking shaft with locking portions on the top and bottom, and an engaging portion formed at one end of one of the metal plates, and the locking portions at both ends of the locking shaft are connected to the pair of locking portions. A locking portion of the support shaft is configured to lock the metal plate, and an engaging portion formed at one end of the metal plate is configured to engage with the locking portion of the support body. It is characterized by detecting the position.

[Function] The reference position detection device for a magnetic head according to the present invention detects the highest sensitivity part which becomes the reference position by passing the magnetic head between the knife blades of the high magnetic flux density generating device when measuring the magnetization distribution state of the magnetic rotor. The reference position is determined based on the number of pulses sent from the stepping motor that moves the magnetic head forward and backward at the same time as the detection, and thereby the reference position can be automatically positioned and set with high precision in a short time.

[Example] Next, an example of the reference position detection device for a magnetic head according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a sectional view of a magnetic herad reference position detection device showing an embodiment of the present invention, and FIG. 2 is a sectional view taken along line A-A in FIG. 1.
FIG. 3 is a front view of the feed ellipse of the magnetic head, and FIG. 4 is an overall perspective view of a rotor magnetization distribution measuring device equipped with a magnetic head reference position detecting device according to the present invention.

In the figure, reference numeral 10 indicates a magnetic head for detecting the magnetization distribution of a rotor used in a brushless motor.

In order to detect this magnetization distribution, it is necessary to detect the position of a Hall element (not shown) buried in the flat part of the tip of the magnetic head 10 to find a reference position that is the most sensitive part.

That is, the high magnetic flux density generator 1 used for this detection
1 is a metal plate 16a made of a pair of magnetic materials, the tip of which is bent to form a knife 14;
16b and a magnet 17 sandwiched between the pair of metal plates 16a and 16b, thereby forming a minute gap between the knives 14.

More specifically, in order to sandwich the magnet 17 between the pair of metal plates 16a and 16b and at the same time to support them with a predetermined distance between them, there are non-contact holes in front (knife 14@) and behind the pair of metal plates 16a and 16b. A magnetic locking shaft 22 and a pair of support shafts 25a and 25b are provided, respectively.

And the lock fl! 122 is the metal plate 25a, 25b 31! There are locking parts 20a and 20 at the upper and lower ends of the
b (convex center) is formed, and one metal plate (upper ja
il) A protruding engagement portion 24 is provided at the rear end of the 16a.

The high magnetic flux density generator 11 configured in this way is supported by support shafts 18 and 30 disposed above and below the generator 11, and at the same time, the engaging portion 24 at the rear of the upper metal plate 16a is connected to a support member to be described later. It engages with the vertically elongated hole 36 of 34 to regulate its lateral vibration.

In this case, the support shaft 22 is composed of a main shaft 18 and an auxiliary shaft 30, which are arranged on the same axis as the base 12 and the support 3.
4, each rotatably supported.

On the other hand, a case 13 is inserted and fixed into the through hole 15 of the base 12, and a housing 19 is inserted into the opening of the case 13.
is inserted, and a flange 19a formed at the upper edge of the housing 19 is fixed with bolts. A pair of bearings 23a and 23b are inserted above and below a through hole formed in the center of the housing 19, and a main shaft 18 having a concave center 31 formed at its upper end is rotatably supported by the bearings 23a and 23b. has been done.

Further, a pulley 27 is fixed to the lower part of the main shaft 18 via a set screw, and the lower bearing 23b uses the boss portion of the pulley 27 to press the inner ring of the bearing 23a in the axial direction to apply a preload to it.

Similarly, for the upper bearing 23a, a cap 37 is attached to the main shaft 18 that has passed through the upper bearing 23a.
By inserting a preload collar 39 and a wave washer 39a between the cap 37 and the upper bearing 23a and pressing them to fix the cap 37, the inner ring of the upper bearing 23a is elastically pressed and preloaded. is giving.

On the other hand, a concave center 31 of the main shaft 18 is located at the upper part of the main shaft 18.
The auxiliary shaft 3 has a concave center 32 formed at its lower end to face the
0 are arranged on the same axis, and this auxiliary shaft 30 is connected to the support body 3.
4 is rotatably and axially slidably supported via a linear ball bearing 28 inserted in the shaft.

Note that this linear ball bearing 28 is normally manufactured in the market, and its outer ring is fixed in the insertion hole 26 of the support body 34, and a plurality of balls 28a are inside thereof rotated via a retainer. It has a structure that allows it to be supported freely.

In this way, the locking shaft 22 of the high magnetic flux density generator 11
Both upper and lower ends engage with concave centers 3 and 32 formed at mutually opposing ends of the main shaft 18 and the auxiliary shaft 30, respectively, and are supported on the same axis.

In this case, a predetermined weighed weight 42 is removably inserted into the upper part of the auxiliary shaft 30, so that the upper and lower sides of the locking shaft 22 are supported with appropriate pressing force, and at the same time, the rear end of the upper metal plate 16a By engaging the engaging portion 24 of the support #: 34 with the longitudinal hole 36 formed on the inner surface, the high magnetic flux density generator
1 can be supported in a stable state.

Next, the feeding mechanism for moving the magnetic head 10 forward and backward will be explained with reference to FIGS. 3 and 4.

That is, a threaded rod 46 rotatably supported on the same base is disposed parallel to the pillar 44 in the vicinity of the pillar 44 erected on the base 12, and the threaded rod 46 is provided on the longitudinal guide surface of the pillar 44. L that moves up and down by manual rotation operation.
A letter-shaped sliding base 48 is operatively guided and supported. A magnetic head 10 is mounted on a holder 50 that is guided and supported so as to be movable forward and backward on the horizontal surface of the slide base 48.
The main body part of is fixedly supported.

Further, a stepping motor 40 is attached to the end of a bracket 52 fixed to the front side of the slide base 48, and a screw shaft 54 directly connected to an output shaft (not shown) of the stepping motor 40 is attached to the end of a bracket 52 fixed to the front side of the slide base 48. is configured such that an engaging pin 56 provided on the holder 50 side is resiliently pressed into engagement.

The feed mechanism configured in this manner rotates the stepping motor 40 to move the magnetic head 10 in the axial direction via the screw shaft 54 of the motor 40 and the pin 56 elastically engaged with the screw shaft 54. It can be moved forward and backward.

Therefore, the high magnetic flux density generating device 11 of the reference position detecting device constructed as in the present invention generates a focused magnetic flux from the knife blades 14 facing each other, and the magnetic flux density measuring device 38 is generated between the knife blades 14 shown in FIG. By moving the magnetic head 10 at the tip by the stepping motor 40 in a straight line, it is possible to know the reference point at which the Hall element embedded in the magnetic head 10 has the highest sensitivity.

Therefore, the reference position of the magnetic head 10 is automatically detected by the number of pulses sent from the stepping motor 40 when the magnetic head 10 is moved in the axial direction by the stepping motor 40, and this can be set in a short time and with high precision. I can do it.

[Effects of the Invention] As is clear from the embodiments described above, the reference position detection device for a magnetic head according to the present invention is capable of detecting a magnetic head in a radial direction with respect to a magnetic rotor in which both ends of a central shaft are rotatably held between a pair of upper and lower support shafts. A reference position detection device for a magnetic head that detects the characteristics of magnetization distribution by moving the magnetic head to the magnetic head, which comprises: a pair of support shafts; a high magnetic flux density generator sandwiched between the pair of support shafts; It consists of a flat rod-shaped magnetic head that moves forward and backward with respect to the device, and the pair of support shafts include a main shaft that is rotatably supported on the base and has a locking part at the tip, and a magnetic head that rotates and moves along the axis of the main shaft. an auxiliary shaft that is supported so as to be slidable in the axial direction and has a locking portion facing the main shaft at its tip; the base for supporting the auxiliary shaft;
The high magnetic flux density generating device is composed of a pair of metal plates each having a knife edge formed by bending the tip thereof, and a pair of metal plates arranged in parallel so as to face each other with a predetermined distance between the knife edges. A locking shaft is provided, and a magnet is sandwiched between the pair of metal plates, the metal plates are supported through the pair of metal plates, and a locking shaft is provided with locking portions at the top and bottom, and one of the metal plates is extended and formed at one end thereof. The locking portions at both ends of the locking shaft are locked by the locking portions of the pair of support shafts, and the locking portion formed at one end of the metal plate is connected to the support. By configuring it to engage with the engaging part of the knife, the magnetic head is passed between the knives to detect the highest sensitivity part which becomes the reference position, and the reference position is determined by the number of pulses sent from the stepping motor that moves the magnetic head forward and backward. By determining the position, the reference position of the magnetic head can be automatically positioned and set with high precision in a short time.

Although the preferred embodiments of the present invention have been described above, it is needless to say that the present invention is not limited to the above-described embodiments and that various design changes can be made without departing from the spirit of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a reference position detection device for a magnetic head showing an embodiment of the present invention, FIG. 2 is a sectional view taken along line A-A in FIG. 1, and FIG. 3 is a front view of a feeding mechanism that supports a magnetic head. is a diagram,
FIG. 4 is an overall perspective view of a magnetization distribution measuring device for a magnetized rotor using the magnetic head reference position detection device according to the present invention, FIG. 5 shows a brushless motor, and FIG. 5(a) shows a brushless motor. FIG. 5(b) is a vertical cross-sectional view, and FIG.
It is a B-BWfr plane view of figure (a). 10...Magnetic head 11...High magnetic flux density generator 12...Base 14...Knifetsu 17...Magnet 13...Cases 16a, 16b =--Metal plate 18...Main shaft 20a, 20b...Locking part (convex center) 3, 32.
... Stop part (concave center) 22 ... Locking shaft 23a ... Upper bearing 23b ... Lower bearings 25a, 25b ... Support shaft 24 ... Engagement part 2
8... Linear ball bearing 30... Auxiliary shaft 34... Support body 36.
・Vertical hole 38 ・Magnetic flux density measuring device 40 ・Stepping motor 42 ・1!1m 44 ・Strut 46
...Screw rod 48...Slide base 50
...Holder 52...Bracket 54...
・Screw shaft 56...Engaging pin 60...Rotor 62...Rotor machining net 62a...
Rotating shaft 62b...Magnetized surface 96...Sector coil 97...Stator 98...Yoke
98a...Insulating surface 100...Hall element IG Drawing engraving G Procedural amendment (method) 2 Title of invention Magnetic force/\Rad U level 10,000 detection head 3, If amendment is made, relation to the case Patent applicant Address: 167 Higashi-Ome-chome, Takaume-shi, Tokyo Name: Nippon Chemi-Con Co., Ltd. Representative name: Toshiaki Sato 4, Agent 6 Subject of amendment (1) Drawing FIG. (G) (b)

Claims (1)

[Claims] (1) In a reference position detection device for a magnetic head that detects characteristics of magnetization distribution by moving in the radial direction a magnet rotor in which both ends of a central shaft are rotatably held between a pair of upper and lower support shafts, the pair of supports It consists of a shaft, a high magnetic flux density generator held between the pair of support shafts, and a flat rod-shaped magnetic head that moves forward and backward with respect to the high magnetic flux density generator. a main shaft that is rotatably supported on the axis of the main shaft and has a locking portion at its tip, and an auxiliary shaft that is rotatably and slidably supported on the main shaft axis and has a locking portion at its tip that faces the main shaft. , a support provided on the base to support the auxiliary shaft, and the high magnetic flux density generator includes a pair of metal plates each having a bent tip to form a knife edge, and the knife. a locking shaft which is arranged parallel to each other so that their edges face each other with a predetermined spacing between them, a magnet is sandwiched between the pair of metal plates, the locking shaft extends through and supports these metal plates, and has locking portions on the top and bottom; and the metal plate. and an engaging part formed at one end of the extending part,
The locking portions at both ends of the locking shaft are locked by the locking portions of the pair of support shafts, and the engaging portion formed at one end of the metal plate is configured to engage with the engaging portion of the support body. A reference position detection device for a magnetic head, characterized in that the reference position is detected by passing the magnetic head between the knife edges.