JP2000065596A5 - Magnetic encoder and motor with magnetic encoder - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a motor with magnetic encoder and a magnetic encoder for detecting the rotational position of the servo motor used in robots, machine tools.

0003
[Problems to be Solved by the Invention]
However, in the first conventional example, there are the following problems.
(1) Since the tracks for recording each bit signal are arranged in the axial direction, increasing the number of bits increases the length in the axial direction, making it difficult to reduce the size.
(2) As the number of trucks increases, the number of magnetized points increases and the processing man-hours increase.
(3) Since a magnetoresistive element is provided corresponding to each track, as the number of bits increases, the number of wires increases, the assembly work becomes complicated, the work man-hours increase, and the cost increases.
Further, in the second conventional example, there are the following problems.
(1) Since there is only one magnetic sensor, the absolute position of the rotating body cannot be obtained.
(2) Since the magnetic sensor detects the magnetic flux near the magnetic pole boundary line of the magnet, the linear portion of the output waveform can be used, but the accuracy of the sine wave waveform is lowered, and the detection accuracy of one rotation is lowered. Further, in the third conventional example, the outer circumference of the rotating body is provided with undulations in which the magnetic field changes in a sinusoidal shape. However, for example, in an ultra-small rotation detector that detects rotation of a micromotor or the like, the outer shape of the rotating body is Since it is extremely small, it is extremely difficult to accurately process the outer shape of the rotating body into a sinusoidal unevenness or an elliptical shape, and it has not been possible to obtain a rotation detector with high detection accuracy.
Therefore, an object of the present invention is to provide a magnetic encoder and a motor with a magnetic encoder, which have a simple structure, high accuracy, and are inexpensive.

0004
[Means for solving problems]
In order to solve the above problems, the present invention according to claim 1 is a magnetic field detection in which a magnetizing body that generates a magnetic field attached to a rotating body and a magnetic field detection that is attached to a fixed body so as to face the magnetizing body via a gap. In a magnetic encoder including an element and a signal processing circuit for processing a signal from the magnetic field detection element, the magnetizing body is a disk-shaped or rectangular body arranged at an axial end of the rotating body. It is composed of a permanent magnet and is magnetized in one direction perpendicular to the axial direction of the rotating body, and the magnetic field detection element is arranged with the permanent magnet in the axial direction via a gap.
According to the second aspect of the present invention, in the magnetic encoder according to the first aspect, the magnetic field detection elements are arranged concentrically with respect to the rotation center of the rotating body and have a mechanical angle of 90 degrees in the circumferential direction. Two pairs of magnetic field detection elements that are out of phase are provided at positions that are 180 degrees out of phase with each other, and the signal processing circuit processes a differential signal between the magnetic field detection elements that face each other. A differential amplifier is provided to detect the absolute value of the position of the rotating body.
The present invention of claim 3 relates to a motor with a magnetic encoder, and includes the magnetic encoder according to claim 1 or 2 and a servomotor whose rotation position is detected by the magnetic encoder. is there.

Claims (3)

A magnetic generator for generating a magnetic field attached to the rotating body, a magnetic field detection element attached to the fixed body so as to face the magnetic generator through a gap, and a signal processing circuit for processing a signal from the magnetic field detection element In a magnetic encoder with
The magnetism member is composed of a disc-shaped or rectangular parallelepiped permanent magnet disposed at the axial end of the rotating body, and is magnetized in one direction perpendicular to the axial direction of the rotating body. The magnetic encoder is characterized in that the magnetic field detecting element is arranged axially with a gap in the permanent magnet. The magnetic field detection elements are arranged concentrically with respect to the rotation center of the rotating body, and two pairs of magnetic field detection elements that are 90 degrees out of phase with each other in the circumferential direction are 180 degrees out of phase with each other. The signal processing circuit is provided with a differential amplifier for processing differential signals between the magnetic field detection elements facing each other, and detects the absolute value of the position of the rotating body. The magnetic encoder according to claim 1, wherein the magnetic encoder is configured as described above. 3. A motor with a magnetic encoder, comprising: the magnetic encoder according to claim 1; and a servo motor capable of detecting a rotational position by the magnetic encoder.