JPH03201420A - Manufacture of multipolar magnet with plurality of magnetizing tracks - Google Patents

Abstract

PURPOSE:To magnetize a plurality of tracks of uniform phases at a high yield rate by a method wherein the change in magnetic flux of the first track of a drum is detected, and magnetization on the second and following tracks is conducted based on the detected change of magnetic flux. CONSTITUTION:The first track is magnetized. A magnetizing head 3 is opposingly positioned on a drum 1, and 100 poles are magnetized by intermittently applying a current to the magnetizing head 3 by the signal of a reference encoder 4 which is positioned on the same axis. A head having a magnetic sensor 6 at its tip is used as a magnetizing head 3. When the second track is magnetized, the magnetizing head 3 is shifted to the position opposing to the second track 1b of the drum 1. Then, the change in magnetic flux of the first track 1a is read out by the magnetic sensor 6. The change in magnetic flux of the first track is recorded in RAM, the change is read out when the second track is magnetized, and the application of current to the magnetic head is controlled by the output of the above-mentioned change.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a multipolar magnet having a plurality of magnetized tracks on one drum and used for encoders and the like.

Conventional technology: In multi-polar encoder magnets in which N and S poles are alternately magnetized at minute intervals, the drum (magnet molded product) to be magnetized is
The drum is rotated, and signals from a reference encoder placed coaxially with the drum control the on/off of energization to the magnetizing head facing the drum, thereby performing multi-pole magnetization. When magnetizing, for example, an origin signal to a track other than this magnetized track (first track) (second track, third track, etc.), simply turn the magnetizing head. In the method of moving the position to another track, it is difficult to match the phase with the signal of the previously magnetized track. If the magnetizing head is moved to another track, the magnetizing head will always swing on a plane perpendicular to the direction of movement of the magnetizing head, so it was desired to obtain a drum with a high yield in which the magnetization phases of the plurality of magnetizing tracks were aligned.

It is also conceivable to install a plurality of magnetizing heads at different intervals and magnetize a plurality of tracks at the same time. However, it is difficult to prevent magnetic interference between the magnetized heads, and it is difficult to accurately position and align a plurality of magnetic heads, resulting in many problems.

Problems to be Solved by the Invention The problem to be solved by the present invention is to align the magnetization phases between the tracks in manufacturing a multipolar magnet having a plurality of magnetized tracks on one drum.

Means for Solving the Problems In the method according to the present invention, the magnetization work is performed as follows.

After the first track is magnetized, the second and subsequent tracks are magnetized.
The system uses a method in which electricity is turned on and off to the magnetizing head facing the drum while rotating the drum. The present invention is characterized in that the on/off control of the energization is performed by detecting the magnetism of the tenth magnetized track, which has already been magnetized, and using the output signal thereof.

As a method for controlling the intermittent supply of electricity to the magnetic head, in parallel with the magnetic detection of the 10th magnetized track from the rotating drum, control of the intermittent supply of electricity to the magnetic head is performed based on the detection output. Although it may be carried out, the following method is preferable.

That is, the magnetism of the first magnetized track is detected and the output thereof is stored in advance in the memory of the computer. In this method, when magnetizing the second and subsequent tracks, energization to the magnetizing head is controlled based on the signal read from the memory.

Operation In the method according to the present invention, the signal used to magnetize the second and subsequent tracks is obtained from the magnetization output of the first track, which has already been magnetized. The intermittent control of the current to the magnetic head is performed using the signal of the magnetization output of the first track. This can be achieved with

Example When carrying out the method according to the present invention, the first track of the drum is magnetized using a method using a magnetizing yoke (the drum to be magnetized is attached to a yoke made by winding an electric wire around a grooved yoke). The commonly used methods include the method of using a magnetizing head (rotating the drum to be magnetized, and then intermittent energization of the opposite magnetizing head). You can adopt the method that you have.

The means (magnetic sensor) for reading changes in the magnetic flux of the first magnetized track is a Hall element, a magnetoresistive element, or the like. The output of the magnetic sensor is subjected to appropriate processing such as amplification and digitization, and is used as a signal for intermittent energization of the magnetizing head when magnetizing the second and subsequent trunks.

This will be explained in detail below.

As shown in FIG. 4, an encoder magnet having a first magnetized track 1a and a tenth magnetized track 1b on a drum 1 (magnet molded product with a diameter of 40 mm) is manufactured. On the 10th magnetized track, N and S poles are magnetized by 100 poles. Furthermore, the second track is magnetized at one location for use as an origin signal.

First, the first track is magnetized. As shown in FIG. 1, the drum 1 is mounted on a rotating machine #12 and rotated.

A magnetizing head 3 is opposed to the drum 1, and 100 poles are magnetized by intermittent energization of the magnetizing head 3 based on a signal from a reference encoder 4 placed on the rotating mechanism 2 coaxially with the drum 1. (The switch 20 is on the A side, the switch 21 is on the C side, and the signal from the reference encoder 4 and the origin signal 4' are given to the energization control section 5).

As the magnetizing head 3, as shown in FIG. 2, a magnetic sensor 6 is attached to the tip thereof. When magnetizing the second track, the magnetizing head 3 is moved so as to face the second track of the drum l. Then, the magnetic sensor 6 reads changes in the magnetic flux of the first track.

That is, the switch 20 is set to the B side and the switch 22 is set to the F side, the signal from the reference encoder 4 is input to the counter 7, and the address of the RAM (random access memory) 8 is determined by this signal. At the same time, a rectangular wave obtained by amplifying and waveform-shaping the output of the magnetic sensor 6 obtained from the tenth magnetized track is recorded as data. Next, set the switch 20 to the B side, the switch 21 to the D side, and the switch 22 to the E side, read out the data recorded in the RAM 8, use the origin signal 4' as a trigger, take out the first cycle, and amplify this signal. By controlling the current supply to the magnetic head 3, magnetization was performed at one location/rotation.

When the magnetic fluxes of the first and second tracks of the magnetized drum were measured, they were found to be in phase, as shown in FIG.

In the above embodiment, the change in the magnetic flux of the first track is recorded in advance in the RAM, and read out when the second track is magnetized. However, in parallel with detecting the change in the magnetic flux of the first track with a magnetic sensor, the method according to the present invention also includes controlling the energization of the magnetic head based on this output. In this case, if the magnetizing head and the magnetic sensor are located close to each other, the magnetic field of the magnetizing head tends to affect the magnetic sensor and disturb the detection of the magnetic flux of the first track.

In such a case, the method described in the above embodiment is more preferable. Further, if data is recorded in the RAM in advance, the phase can be finely adjusted by electrical means, such as by shifting the address of the memory.

Effects of the invention When a single drum has multiple magnetized trunks,
In order to magnetize each track, simply replace the magnetic head or move it to a predetermined track and magnetize it using the signal from the reference encoder 4 shown in Figure 1, the phase of magnetization of each track will be random. . Considering two tracks, the probability that the phases of both tracks will be within ±45' electrical angle is 25%, which is very poor in terms of yield.

Further, even if the magnetizing head is installed on a mounting base that can be moved with precision, it is extremely difficult to fix the magnetization head in a position where the phases are accurately aligned.

However, in the method according to the present invention, since the change in the magnetic flux of the first track of the drum is detected and the second and subsequent tracks are magnetized based on this, the plurality of tracks are magnetized with the same phase. can be carried out with good yield.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a magnetizing device used in an embodiment of the present invention, Fig. 2 is a perspective view of a magnetizing head used in the same, and Fig. 3 shows the surface magnetic flux density of a magnetized drum. The curve diagram, FIG. 4, is a perspective view of a drum magnetized in two tracks.

Claims (3)

[Claims] 1. In manufacturing a multipolar magnet that has multiple magnetized tracks on one drum, after the first track is magnetized, the second and subsequent tracks are magnetized using a magnetizing head that faces the drum while rotating the drum. A method of intermittent energization is performed, and the intermittent energization is controlled by detecting the magnetism of the first magnetized track that has already been magnetized and using an output signal thereof. Method of manufacturing multipolar magnets with magnetic tracks. 2. The magnetism of the first magnetized track is detected, the output signal thereof is stored in advance in the memory of the computer, and when the second and subsequent tracks are magnetized, the magnetization head is energized by the signal read from the memory. 2. A method for manufacturing a multipolar magnet having a plurality of magnetized tracks according to claim 1. 3. A multipolar magnet having a plurality of magnetized tracks according to claim 1, wherein in parallel with performing magnetic detection of the first magnetized track, on/off control of energization to the magnetized head is controlled based on the detection output. manufacturing method.