JPS63182808A - Manufacture of magnet for magnetic encoder - Google Patents

Abstract

PURPOSE:To make a magnetic encoder small-sized with a sufficient flux used by a method wherein a ring magnetic plate is magnetized to a single polarity, the magnetic plate is cut into a ring shape and neighboring tracks are turned and deviated in the circumferential direction to obtain a sufficient magnetic flux. CONSTITUTION:A magnetic plate 4 consisting of a ring rubber magnetic material is inserted into a non-magnetic guide 3 to be fixed with a magnetic circuit tap 5. A coil to be magnetized is made conductive by a short-circuit current. After magnetization, an N pole and an S pole are formed on each semicircle, right and left. A magnetic plate 4 is cut by a cut-away line 6 to be divided into two ring magnets 4a and 4b and either of them, here the magnet 4b on the inner side is turned by 180 deg.. The magnets 4a and 4b are fixed with adhesives. Thereby, sufficient magnetic property can be obtained thus to be able to make a magnetic encoder small-sized.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a magnet used in a magnetic encoder that detects the rotation speed and position of a motor [Prior Art] Detection magnetic field generation used in a magnetic encoder Normally, as shown in FIG. 4, the surface of an annular magnet 12 that faces the magnetoresistive element 13 of the annular magnet 12 fixed to the support plate 11 of the rotating shaft 10 is 180" or 90" in the circumferential direction. The polarity is changed, and the outer side 12a and inner side 12b of each magnetic pole part are configured to have different poles.

This is to create a radial magnetic flux with respect to the magnetic resistance element 13 facing the magnetic pole surface. 14 is a bias magnet. Therefore, in the case of FIG. 4, it is required to magnetize the magnet 12 so that the surface has four magnetic poles, and as shown in FIG. , lb, lc
, ld, and a sixth magnetizing filter 2 is provided on each magnetizing pole.
As shown in the figure, a magnetizing device that is folded and wound is used, and a magnet plate is fixed to the magnetizing yoke and a pulse current is applied to magnetize the plate in the thickness direction.

[Problem that the invention seeks to solve]

Therefore, the structure of the 9 magnetizing yoke is complicated, and the 1 magnetizing coil is often folded back.Especially, as magnetic encoders become smaller, as the size of the magnet decreases, the space for the magnetizing coil becomes larger, and the 1 magnetizing pole becomes smaller. It is not possible to increase the magnetizing force.

There was a drawback that a sufficient detection magnetic field could not be obtained.

(Objects of the Invention) Therefore, two objects of the present invention are to provide a method for manufacturing a magnetic encoder magnet, which simplifies the magnetizing device and allows a magnetic encoder magnet with a small diameter to obtain a sufficient detection magnetic field.

[Means for solving problems]

For this purpose, a number of magnetizing poles equal to the number of magnetic poles in the circumferential direction of the magnet are provided in the circumferential direction of the magnetizing yoke, and the annular magnet plate is magnetized with a single polarity in the radial direction by the magnetizing poles. Before or after magnetization, it is cut into a ring shape into a required number of tracks, and after one magnetization, adjacent tracks are rotationally displaced in the circumferential direction according to the pole spacing.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 2 shows the magnetizing device used in the present invention.

1 is a magnetizing yoke with two magnetic poles la and l divided in the circumferential direction.
b. A magnetizing coil 2 surrounds the magnetizing poles 1a and Ib as shown in FIG. 3 is a non-magnetic guide, 4 is an unmagnetized magnet plate, and 5 is a magnetic circuit holder.

First, a magnet plate 4 made of an unmagnetized annular rubber magnet material is inserted into the nonmagnetic guide 3 and fixed with a magnetic circuit presser 5. Next, apply 500μ to the magnetizing coil 2 with a diameter of 1mm at 600V.
Magnetization is performed by applying a short circuit current with a capacity of F. Therefore, after magnetization, as shown in FIG. 1(a), an N pole and an S pole are formed on each of the left and right half circumferences.

As shown by the cutting line 6 in FIG. 1(b), this magnet plate 4 is
Two large and small annular magnets 4a are cut concentrically.

In this case, the inner ring-shaped magnet 4b is rotated 180 degrees so that two tracks each having two magnetic poles have different polarities as shown in FIG. 1(c). A magnet for a magnetic encoder is obtained by forming such an annular magnet and fixing it to a support plate (not shown) with an adhesive. Note that 7 is a match mark.

Further, the cutting line 6 may be processed before magnetization, and in the above embodiment, each track has two magnetic poles, but when four magnetic poles are provided, magnetization is possible. yoke 1
It is sufficient to divide the magnetized pole into four pieces in the circumferential direction.

〔Effect of the invention〕

As described above, according to the present invention, a required number of magnetized poles are provided in the circumferential direction of a magnetized yoke, and one magnetized magnet is cut into a magnet plate before or after magnetization to form a plurality of concentric annular tracks. by forming and circumferentially circumferentially displacing adjacent tracks by a pole spacing.

Since the magnetic flux is formed in the radial direction between the tracks, there is no need to divide the six magnetizing yokes in the radial direction and provide magnetizing poles. Since it is possible to obtain an annular magnet having a magnetic flux of 9 and ensure magnetization, sufficient magnetic flux can be obtained even in a small magnet, which has the effect of downsizing the magnetic encoder and improving accuracy.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the manufacturing process of a magnet for a magnetic encoder according to the present invention, Fig. 2 is an exploded perspective view schematically showing a magnetizer used in the present invention, Fig. 3 is a top view of the magnetizing yoke, and Fig. The figure is a perspective view showing a state in which a conventional magnetic encoder magnet is used, and FIG. 5 is a perspective view showing a part of a conventional magnetizing device.
FIG. 6 is a top view thereof. 1 is a magnetizing yoke, 2 is a magnetizing coil, 3 is a non-magnetic guide,
4 is a magnet plate, 5 is a magnetic circuit presser, 6 is a cutting line, 7 is a matching mark, 11 is a support plate, and 12 is a magnet. 13 is a magnetoresistive element. Fig. 1 Fig. 2 1 1 Magnetizing yoke

Claims (1)

[Scope of Claims] 1. In an annular magnetic encoder magnet that has a plurality of concentric tracks each having different magnetic poles arranged in the circumferential direction, and in which adjacent tracks have mutually different polarities to form a radial magnetic flux. , the magnetizing yoke is provided with the number of magnetizing poles required for one track, the annular magnet plate is concentrically cut into the required number of tracks before or after magnetization, and the pole spacing of the tracks is determined after magnetization. 1. A method of manufacturing a magnet for a magnetic encoder, characterized in that adjacent tracks are rotationally displaced in the circumferential direction according to the . 2. The method of manufacturing a magnet for a magnetic encoder according to claim 1, wherein the magnet plate is a rubber magnet.