JP2003028667A - Magnetic encoder and its output method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the eccentric state of a detecting gear using a disc without tooth and furthermore to use an eccentricity detection output indicating the eccentric state to correct the amplitude of an encoder signal. SOLUTION: This magnetic encoder and its output method use a disc (3) that has the same core as a detecting gear (2) and no tooth, and an eccentricity detection output (6) that the eccentric state of the disc (3) is detected is used to correct the amplitude of an encoder signal (4), resulting in a corrected encoder signal (5A) that is accurate and is not affected by eccentricity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic encoder and an output method thereof, and more particularly, to a disk which is concentric with a detection gear and has no teeth, and the rotation of the disk is detected by a magnetoresistive element. The present invention relates to a new improvement for detecting an eccentricity state of a detection gear and a disc, correcting an amplitude of an encoder signal by using an eccentricity detection output, and correcting an eccentricity error of an encoder signal to improve accuracy.

[0002]

2. Description of the Related Art As a magnetic encoder of this type which has been conventionally used, although not shown, the rotation of a detection gear is detected by a magnetoresistive element, and the obtained encoder signal is subjected to waveform shaping to obtain an A / A signal. It was D-converted.

[0003]

Since the conventional magnetic encoder is configured as described above, there are the following problems. That is, since the detection gear is fitted to the rotary shaft, if the detection gear is eccentric to this rotary shaft, the detected encoder signal has a sway component corresponding to the eccentricity. Would be superposed, and the accuracy of the encoder signal itself would be reduced.

The present invention has been made in order to solve the above problems, and in particular, a disc having no teeth is provided coaxially with the detection gear, and the rotation of the disc is detected by a magnetoresistive element. The magnetic encoder is designed to detect the eccentricity of the detection gear and the disc, correct the amplitude of the encoder signal using the eccentricity detection output, and correct the eccentricity error of the encoder signal to improve the accuracy. And its output method.

[0005]

In the magnetic encoder and the output method thereof according to the present invention, the rotation of the detection gear is detected by the first magnetoresistive element provided in the vicinity of the detection gear made of a magnetic material. In the magnetic encoder, a disc concentric with the detection gear and having no teeth is provided, a second magnetoresistive element is provided in the vicinity of the disc, and the disc is eccentric by the second magnetoresistive element. The first magnetic resistance element provided in the vicinity of the detection gear made of a magnetic material detects the rotation of the detection gear and outputs an encoder signal via the first amplifier. In an output method of a rotary encoder, an eccentricity detection output from a second magnetoresistive element provided in the vicinity of a disk which is concentric with the detection gear and has no teeth is set to a reference voltage which is preset through a second amplifier. In comparison, feedback control is performed to make the amplification factor of the second amplifier variable so that the output of the second amplifier becomes equal to the reference voltage, and the amplitude of the encoder signal is multiplied by the amplification factor of the encoder signal. This is a method of correction.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a magnetic encoder and an output method thereof according to the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes a rotary shaft rotatably provided in a casing (not shown), and the detection gear 2 made of a magnetic material and fitted in the rotary shaft 1 has the same structure. A disc 3 is provided with a core and no teeth.

A first magnetoresistive element MR1 is provided in the vicinity of the outer periphery of the detection gear 2 and the disc 3 is provided.
A second magnetoresistive element MR2 is provided in the vicinity of the outer circumference of the. The sinusoidal encoder signal 4 obtained by the first magnetoresistive element MR1 is input to a first input terminal of a first amplifier 5, and the corrected encoder signal 5 is output from the first amplifier 5.
A is obtained.

The eccentricity detection output 6 detected by the second magnetoresistive element MR2 and detecting the eccentricity state of the disk 3 is input to the second input terminal 7a of the second amplifier 7, and the second amplifier 7 is supplied.
The eccentricity detection output 6a after control, which is the output from, is input to the first input terminal 8a of the operational amplifier 8 and the preset reference voltage 9 is input to the second input terminal 8b.

Output 10 obtained from the operational amplifier 8
Is input to the second input terminal 5b of the first amplifier 5 and is also feedback input to the second input terminal 7b of the second amplifier 7.

Next, the operation will be described. First, under the condition that the detection gear 2 and the disc 3 rotate via the rotary shaft 1 and the encoder signal 4 is input to the first amplifier 5,
The eccentricity detection output 6 obtained from the magnetoresistive element MR2 is the second
By being amplified by the amplifier 7 and input to the operational amplifier 8, it is compared with the reference voltage 9, and the output 10 is feedback-input to the second input terminal 7b of the second amplifier 7 and feedback-controlled, so that the voltage level is A non-constant eccentricity detection output 6 having variations due to eccentricity is input to the second amplifier 7, and the output eccentricity detection output 6a after control, which is this output, becomes the same voltage level as the reference voltage 9. As described above, the amplification factor of the second amplifier 7 is always controlled to be variable.

The output 10 whose amplification factor is variably controlled by the second amplifier 7 is the second input terminal 5b of the first amplifier 5.
Is input to the first amplifier 5, and the amplitude of the encoder signal 4 is corrected by multiplying the encoder signal 4 by the amplification factor in the first amplifier 5 to obtain a highly accurate corrected encoder signal 5A without the influence of eccentricity. be able to.

[0012]

Since the magnetic encoder and the output method thereof according to the present invention are configured as described above, the following effects can be obtained. That is, the encoder signal obtained from the detection gear side is corrected for the eccentricity by using the eccentricity detection output obtained from the disc side, and it is possible to obtain a high-precision encoder signal that is not adversely affected by the eccentricity. .

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a magnetic encoder according to the present invention.

FIG. 2 is a waveform diagram showing signals of respective parts of FIG.

[Explanation of symbols]

1 rotation axis 2 Detection gear 3 discs MR1 first magnetoresistive element MR2 second magnetoresistive element 4 encoder signal 5 First amplifier 6 Eccentricity detection output 7 Second amplifier 9 Reference voltage

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2F063 AA35 CB12 CC05 DA05 DD03                       EA03 GA52 GA67 GA69 KA02                       KA04 LA11 LA30                 2F077 AA47 CC02 CC09 NN02 NN03                       NN21 PP14 QQ02 TT35 UU20                       VV01

Claims (2)

[Claims] 1. The detection gear (2) is provided by a first magnetoresistive element (MR1) provided in the vicinity of the detection gear (2) made of a magnetic material.
In the magnetic encoder adapted to detect the rotation of the disc, a disc (3) concentric with the detection gear (2) and having no teeth is provided, and a second magnetoresistive element ( MR2), and the disk by the second magnetoresistive element (MR2)
(3) A magnetic encoder having a configuration for detecting the eccentricity state. 2. The detection gear (2) is provided by a first magnetoresistive element (MR1) provided in the vicinity of the detection gear (2) made of a magnetic material.
In the output method of the magnetic encoder, which detects the rotation of the encoder gear (4) and outputs the encoder signal (4) through the first amplifier (5), the disc (1) is concentric with the detection gear (2) and has no teeth ( 3)
The eccentricity detection output (6) from the second magnetoresistive element (MR2) provided in the vicinity of the reference voltage is preset via the second amplifier (7).
In comparison with (9), the output of the second amplifier (7) is the reference voltage.
Amplitude of the encoder signal (4) is obtained by performing feedback control to make the amplification factor of the second amplifier (7) variable so that the voltage is the same as (9) and multiplying the encoder signal (4) by the amplification factor. An output method of a magnetic encoder characterized by performing correction.