JPH0435692B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in magnets used for signal generation.

2. Description of the Related Art Signal generators such as rotary encoders are conventionally known, and include, for example, a magnet and a Hall element placed near the magnet. The magnets used in such signal generators have a cylindrical rotor with S and N poles alternately arranged in areas on the outer circumferential surface of the rotor, which are divided radially at equal intervals, as shown in Figure 1. It has a magnetized structure. The output waveform from a signal generator using a rotor (magnet) having such a structure is a sine wave as shown in FIG.
For this reason, the magnetization accuracy of the rotor is poor, or if the spacing between the rotor and the stator is not equal, equal waveforms cannot be obtained, and the pulse width fluctuates due to fluctuations in voltage and the influence of noise, making it difficult to obtain accurate magnetization. There was a drawback that no output could be obtained.

The present invention provides a magnet used in a signal generator that is less affected by errors by making the distance between each magnetic pole as narrow as possible and making the width of each magnetic pole relatively wide.

The present invention also provides a magnet used in a signal generator and a method for magnetizing the same, in which a more accurate signal can be obtained by extremely weakening the magnetization near the center of the wide magnetic pole. It is.

The details of the magnet used in the signal generator of the present invention will be explained below based on the illustrated embodiment. FIG. 3 is a perspective view of the magnet of the present invention, showing the cylindrical body 10
Each area 10a, 10b, 10 divided radially
C, . . . are alternately magnetized as S and N poles, respectively. And the magnetic pole pattern as shown in Figure 4 (a diagram showing the expanded circumferential side of the cylindrical body)
The distance between the peaks of adjacent magnetic poles is made as close as possible, and the magnetic poles themselves have a relatively constant spread.

By forming such a pattern of magnetic poles, it is possible to obtain an output signal signal similar to this pattern. That is, the gradient Δy/Δx' of the magnetic flux pattern as it rises from the zero point to the peak is larger than the gradient Δy/Δx of the output signal obtained by the conventional system shown in FIG. Therefore, the error △x' of the present invention when shifted by △y due to the above-mentioned fluctuation is smaller than the error △x of the conventional method, and the signal accuracy is correspondingly higher than that of the conventional method. It becomes possible to take it out.

When forming the magnet of the embodiment described above, the magnetization is carried out by, for example, as shown in FIG. This is done by forming and arranging grooves 13. Note that 14 is a coil.

When magnetized in this way, the parts facing both ends of the yoke are relatively strongly magnetized, but
The portion of the yoke opposite the central portion is considerably weaker. Moreover, in reality, the pattern does not have a sharp shape as shown in the figure. Therefore, the actually formed magnet of the present invention has a pattern as shown by the chain line in FIG. Therefore, the gradient Δy/Δx'' is significantly large compared to the conventional one, and it is possible to obtain a signal with high accuracy, but the accuracy can be further improved by making the gradient even larger.

The second embodiment shown below is a further improved magnet. Figure 6 shows the magnetization pattern of the second embodiment. By making the central part of the magnetic pole extremely weak, the magnetization is done so that a sharp peak is formed between different poles that are close to each other. It is something to do.
As a result, the gradient Δy/Δx of the rise from the zero position becomes extremely large, and Δx, which causes an error when there is a deviation by Δy, becomes extremely small, resulting in a highly accurate output.

A magnetizing method for forming the magnet of this second embodiment will be described. Figure 7 shows the second invention shown in Figure 6.
FIG.
2, . . . are relatively wide yokes, and each of these yokes has recesses 21a, 22a, . Further, these yokes are arranged with narrow gaps between them. 25, 26... are coils wound around each of the yokes 21, 22,.... A cylindrical body 11 to be magnetized is placed in the center of such a device, and a magnetic field is created by passing an electric current through the coil. The lines of magnetic force at this time are as shown in FIG.
1a, 22a, . . . are formed, most of the magnetic lines of force do not pass here, but pass through both end portions 21b, 21c, 22b, 22c, . . . of the yokes 21, 22, . Therefore, a magnet magnetized by such a device is attached to each yoke 2.
Only the portions facing both end portions of 1, 22, . . . have a strong magnetic flux density. In other words, as shown in Figure 6, different poles with high magnetic flux densities are formed close to each other.
A magnet for highly accurate signal generation as described above can be formed.

As explained above, according to the signal generator using the magnet of the present invention, a signal close to a rectangular wave or a signal with a peak wave can be obtained as an output, so even if an error occurs due to the influence of noise etc. is extremely small and can be ignored, so it is possible to obtain an output signal with extremely high accuracy. Further, according to the magnetization method of the present invention for forming the magnet of the present invention, it is possible to easily form the magnet aimed at by the present invention using an extremely simple magnetizing device.

[Brief explanation of drawings]

Figure 1 shows the magnet in a conventional signal generator;
The figure shows the output signal obtained from the above signal generator, the third
The diagram shows a magnet according to an embodiment of the present invention, FIG. 4 shows a magnetization pattern of the magnet according to the above embodiment, FIG. 5 shows a magnetizing device used in forming the magnet according to the above embodiment, and FIG. Another magnetization pattern of the magnet of the second embodiment. FIG. 7 is a diagram showing the configuration of a magnetization device used when forming the magnet of the second embodiment. 11... Rotor, 12, 21, 22... Yoke.

Claims (1)

[Claims] 1 Consisting of an even number of yokes having a concave portion in the center and arranged close to each other along the outer circumferential surface of a cylindrical body, each of the yokes generates a magnetic field in an opposite direction, thereby turning the cylindrical body into a north pole and a south pole. A method of magnetizing magnets used in signal generators in which the magnetic poles are alternately magnetized.