Encoder

Abstract

In an encoder (1), in which N-poles (5) and S-poles (6) of magnets are arranged alternately in a circumferential direction and in which an unequal pitch portion (8) is provided in a part on a the circumference, it is aimed that the encoder (1) having the unequal pitch portion (8) can be easily manufactured without using a magnetizing head of a special shape having an unequal pitch portion. The unequal pitch portion (8) is formed by arranging the N-poles (5) and the S-poles (6) at an equal pitch all over the circumference and then providing a part on the circumference with a shielding member (7) for shielding a magnetism. Furthermore, the unequal pitch portion (8) is formed by arranging the N-poles (5) and the S-poles (6) at an equal pitch all over the circumference and then providing a part on the circumference with a cut portion.

Description

technical field [0001] The present invention relates to an encoder used in combination with a magnetic sensor to detect the rotational speed, rotation angle, etc. of a rotating member such as a rotating shaft. Background technique [0002] In the past, such as Figure 5 As shown, there is known an encoder 51 in which N poles 52 and S poles 53 of magnets are alternately arranged at equal intervals in the circumferential direction. Its rotation position is specially designated, and a part of the circumference is set as an unequal-spaced portion 54 of the reference point on the circumference. [0003] However, in the past, in order to form the above-mentioned unequal-pitch portion 54 on the encoder 51, the encoder 51 was manufactured using a special-shaped magnetized head having an unequal-pitch portion on a part of the circumference of the magnetic imparting portion. The magnetized head is dedicated. Therefore, there is an inconvenience that it is necessary to manufacture a m...

AI Technical Summary

Problems solved by technology

[0003] However, in the past, in order to form the above-mentioned unequal-pitch portion 54 on the encoder 51, the encoder 51 was manufactured using a special-shaped magnetized head having an unequal-pitch portion on a part of the circumference of the magnetic imparting portion. The magnetized head is dedicated. There is thus the inconvenience of having to make a magnetized head corresponding to the item of each encoder 51

The special shape of the above-mentioned magnetized head with unequal pitch parts, the shape is complicated and the price is high

[0004] And, as another conventional technology among the present invention, the following encoder is disclosed in the following patent document 1: it is formed by at least one band-shaped magnetized body pasted along its circumferential direction by a ring-shaped supporting member, and At least one place on the circumference of the reference position signal is formed with a detected portion for the reference position signal, the magnetic poles of the opposite end portions of the magnetized body become the same pole, and a gap is formed at the opposite portion of the magnetized body , to detect a reference position signal with a small bottom value in the peak value of the output signal, but the prior art disclosed in this publication does not change the fact that it is necessary to use a magnetized head with a special shape with unequal pitch portions

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