JPH048926B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a magnet used in a magnetic encoder that detects the rotational speed and position of a motor.

[Conventional technology]

As shown in FIG. 4, a magnet for generating a detection magnetic field used in a magnetic encoder usually has a ring-shaped magnet 12 fixed to a support plate 11 of a rotating shaft 10, and its surface facing the magnetoresistive element 13 has a circumferential surface. The polarity is changed at 180° or 90° in the direction, and the outer side 12a and inner side 12b of each magnetic pole part are configured to have different poles, and the magnetic flux φ in the radial direction is applied to the magnetic resistance element 13 facing the magnetic pole surface. I am trying to make it. 1
4 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. ,1b,1c,1
d, and using a magnetizing device in which a magnetizing coil 2 is folded and wound around each magnetizing pole as shown in FIG. It is designed to be magnetized in the direction.

[Problem that the invention seeks to solve]

Therefore, the structure of the magnetizing yoke is complicated, and the magnetizing coil is often folded back.Especially, as magnetic encoders become smaller, the magnet size becomes smaller, the space for the magnetizing coil becomes larger, and the magnetizing pole becomes smaller. Since it is small, the magnetizing force cannot be increased and a sufficient detection magnetic field cannot be obtained.

[Purpose of the invention]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for manufacturing a magnetic encoder magnet, which simplifies the magnetizing device and allows a sufficient detection magnetic field to be obtained even with a magnetic encoder magnet having a small diameter.

[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. The plate is cut in an annular shape into a required number of tracks before or after magnetization, and after magnetization, adjacent tracks are rotationally displaced in the circumferential direction according to the pole spacing.

〔Example〕

The present invention will be explained in detail below with reference to the drawings.

FIG. 2 shows a magnetizing device used in the present invention, in which 1 is provided with two magnetic poles 1a and 1b divided in the circumferential direction by a magnetizing yoke. A magnetizing coil 2 surrounds the magnetizing poles 1a and 1b as shown in FIG. 3 is a non-magnetic guide, 4 is an unmagnetized magnetic plate,
5 is a magnetic circuit presser.

First, the magnet plate 4 made of an unmagnetized annular rubber magnet material is inserted into the non-magnetic guide 3, and the magnetic circuit presser 5 is inserted into the non-magnetic guide 3.
Fix it with. Next, add magnetizing coil 2 with a diameter of 1 mm.
Magnetization is performed by applying a short circuit current of 500 μF at 600 V. Therefore, after magnetization, as shown in Figure 1a,
A north pole and a south pole are formed on each half of the left and right sides. This magnet plate 4 is cut concentrically into two large and small annular magnets 4a and 4b as shown by the cutting line 6 in FIG.
Rotate b by 180 degrees and rotate each part by 2 as shown in Figure 1 c.
A ring-shaped magnet is formed in which two tracks with different magnetic poles have mutually different polarities.
A magnetic encoder magnet is obtained by fixing it to a support plate (not shown) with an adhesive. In addition, 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. The magnetized poles of the yoke 1 may be divided into four in the circumferential direction.

〔Effect of the invention〕

As described above, according to the present invention, the necessary number of magnetized poles are provided in the circumferential direction of the magnetized yoke, and the magnetized magnet is cut into a plurality of concentric annular tracks by cutting the magnet plate before or after magnetization. By forming a magnetizing yoke and rotating and deflecting adjacent tracks in the circumferential direction by the pole spacing, a radial magnetic flux is formed between the tracks. There is no need to provide magnetic poles, and it is possible to obtain an annular magnet with multiple tracks and radial magnetic flux using a simple magnetizing device, ensuring reliable magnetization, so even small magnets can have sufficient magnetic flux. This has the effect of miniaturizing the magnetic encoder and improving accuracy.

[Brief explanation of drawings]

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. This figure is a perspective view showing a state in which a conventional magnetic encoder magnet is used, FIG. 5 is a perspective view showing a part of a conventional magnetizing device, and 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 holder, 6 is a cutting line, 7 is a match mark, 11 is a support plate, 12 is a magnet, 13 is It is a magnetoresistive element.

Claims (1)

[Scope of Claims] 1. In an annular magnetic encoder magnet, which has a plurality of tracks concentrically arranged with magnetic poles of different magnetic properties 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 adjusted after magnetization. 1. A method for 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.