JPH07280588A - Encoder - Google Patents

Abstract

PURPOSE:To perform an accurate detection even if a spacing between a magnetic recorder and a magnetic sensor is narrowly set by trisecting a predetermined interval in which N-poles and S-poles are alternately magnetized to be recorded, and forming a magnetic stripe in which both sides are magnetized. CONSTITUTION:When a magnetic recorder 1 is rotated integrally with a rotary shaft 2 of a motor to relatively move, a magnetic sensor 4 outputs a detection signal. In this case, the recorder 1 has a magnetic stripe 6 in which N-poles and S-poles are alternately magnetized to be recorded at a predetermined period T, a non-magnetized part 7 of a central period T2 of the period T trisected from the period T, and magnetic stripes 8 in which both side periods T1, T2 are magnetized to the same poles as those of the stripe 6. Since a reluctance 5 of the sensor 4 is so disposed that magnetized patterns of both the stripes are simultaneously operated, the stripes 8 correct, when the stripe 6 is operated at the reluctance 5 to output a detection signal, an output waveform distortion. Accordingly, even if a spacing between the recorder l and the sensor 4 is narrowly set, the output waveform distortion of the sensor 4 is suppressed to be accurately detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an encoder in which a magnetic recording section is arranged so as to face a magnetic sensor and which outputs an electric signal in response to a displacement caused by relative movement of the magnetic recording section and the magnetic sensor.

[0002]

2. Description of the Related Art For example, a magnetic encoder has been widely used as a device for detecting the rotational position, rotational speed, etc. of a brushless motor. This encoder is composed of a magnetic recording section composed of magnetic stripes in which N and S poles are alternately magnetized and recorded at a predetermined interval on a circumferential surface of a drum rotatable with a rotating shaft of a motor, and the magnetic recording section is opposed to the magnetic recording section. And a magnetic sensor composed of a magnetic resistor arranged with a constant spacing.

With such a structure, when the magnetic recording portion is rotated integrally with the rotary shaft of the motor, the magnetic field generated from the magnetic stripe is changed, and the resistance value of the magnetic resistor acting on this magnetic field is changed. Will also change. In response to this, an electric signal as a detection signal output from the magnetic sensor is output, and thus this electric signal can be used as a control signal for controlling the rotational position, the rotational speed, and the like. In such an encoder, in order to sufficiently increase the magnetic signal input and obtain a stable output, it is necessary to set the spacing between the magnetic recording unit and the magnetic sensor to be narrow.

[0004]

By the way, in the conventional encoder, if the spacing between the magnetic recording portion and the magnetic sensor is set narrow in order to obtain a stable output, the output signal from the magnetic sensor contains many harmonic components. There is a problem that high-precision operation becomes impossible because it is distorted and distorted. For example, in the case of a brushless motor, the FG signal waveform used as a control signal for the rotational position, rotational speed, etc. is ideally a sine wave, but if a relatively wide spacing is set so that a sine wave can be obtained, a magnetic signal is generated. Since the input becomes small, the output fluctuation becomes large and the output waveform becomes wavy.

The present invention has been made in consideration of the above problems. Even if the spacing between the magnetic recording portion and the magnetic sensor is set narrow in order to obtain a stable output, the output waveform of the magnetic sensor is distorted. It is an object of the present invention to provide an encoder that suppresses the above and enables a highly accurate operation.

[0006]

In order to achieve the above object, the present invention according to claim 1 is such that a magnetic recording portion is arranged so as to face a magnetic sensor, and the magnetic recording portion and the magnetic sensor are displaced by relative movement. In the encoder which outputs an electric signal in accordance with the above, the magnetic recording section divides the predetermined interval into three and a first magnetic stripe in which the N and S poles are alternately magnetized and recorded at a predetermined interval. It is characterized in that the central portion of the division is a non-magnetized portion, and both sides have second magnetic stripes magnetized to the same poles as the magnetic poles of the first magnetic stripe.

[0007]

According to the structure of the present invention according to claim 1, the first magnetic stripe is obtained by magnetically recording the magnetic recording portion arranged to face the magnetic sensor by alternately magnetizing N and S poles at a predetermined interval. And the predetermined interval is divided into three, the central portion of the three divisions is a non-magnetized portion, and both sides are second magnetic stripes magnetized to the same pole as the magnetic pole of the first magnetic stripe. The second magnetic stripe acts so as to correct the distortion of the output waveform due to the first magnetic stripe. As a result, even if the spacing between the magnetic recording unit and the magnetic sensor is set to be narrow in order to obtain a stable output, distortion of the output waveform of the magnetic sensor is suppressed, and an encoder that enables highly accurate operation is realized. be able to.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of an encoder of the present invention, in which 1 is a drum 3 rotatable integrally with a rotary shaft 2 of a motor.
The magnetic recording portions 4 formed on the circumferential surface of the magnetic recording element 4 are magnetic sensors each including a magnetic resistor 5 facing the magnetic recording portion 1 with a constant spacing. The magnetic recording unit 1 and the magnetic sensor 4 are configured so that a detection signal can be output from the magnetic sensor 4 when the magnetic recording unit 1 relatively moves by rotating integrally with the rotating shaft 2 of the motor. .

As shown in FIG. 2, the magnetic recording unit 1 has a first magnetic stripe (main magnetized train) 6 in which N and S poles are alternately magnetized and recorded at a predetermined period T, and the predetermined magnetic field. The period T is divided into three parts T1, T2 and T3, and the region of the period T2 at the center of the three divisions is defined as the non-magnetized portion 7, and the regions of the periods T1 and T3 on both sides are the above-mentioned first part. It has a second magnetic stripe (correction magnetized array) 8 magnetized in the same manner as the magnetic poles of the magnetic stripe 6. Here, in order to form the non-magnetized portion 7 of the second magnetic stripe (correction magnetized array) 8, the magnetizing current is stopped when the magnetizing head passes through the area of the period T2 in the central portion. Good. This second magnetic stripe 8
As will be described later, when the magnetic stripe of the magnetic recording unit 1 is made to act on the magnetic resistor 5 of the magnetic sensor 4 to output a detection signal, it works to correct the distortion of the output waveform. The magnetizing pattern is shown in an extremely enlarged horizontal axis for easy understanding of the description.

The magnetic resistor 5 of the magnetic sensor 4 has both magnetization patterns of the first magnetic stripe (main magnetized train) 6 and the second magnetic stripe (correction magnetized train) 8 of the magnetic recording unit 1. Are arranged so as to act simultaneously, and are configured so as to straddle the magnetization patterns of both the first magnetic stripe 6 and the second magnetic stripe 8.

FIG. 3 shows the first magnetic stripe (main magnetized train) 6 of the magnetic recording unit 1 in the encoder of this embodiment.
And the second magnetic stripe (correction magnetized array) 8 acts to show an output waveform of a sine wave output from the magnetic sensor 4, respectively. (A) shows an output waveform obtained by the action of the second magnetic stripe (correction magnetized array) 8,
(B) shows an output waveform obtained by the action of the first magnetic stripe (main magnetized train) 6. As shown in (a), A from the second magnetic stripe (correction magnetized array) 8
Two types of output waveforms A'are obtained. As is apparent from (b), the output waveform obtained from the first magnetic stripe (main magnetized train) 6 contains the third harmonic wave and becomes a distorted electric signal.

However, according to the encoder of this embodiment, the distortion of the output waveform from the first magnetic stripe (main magnetized train) 6 of the magnetic recording unit 1 is caused by the second magnetic stripe (correction magnetized train). ) 8, the output waveforms are combined to be corrected. FIG. 4 is an output waveform obtained by combining the output waveform B from the first magnetic stripe (main magnetized train) 6 with the output waveform A from the second magnetic stripe (correction magnetized train) 8, Reference numeral 5 denotes an output waveform obtained by combining the output waveform B from the first magnetic stripe (main magnetized train) 6 with the output waveform A ′ from the second magnetic stripe (correction magnetized train) 8. ing. In both FIG. 4 and FIG. 5, the depression of the output waveform from the first magnetic stripe (main magnetized train) 6 is filled with the output waveform from the second magnetic stripe (correction magnetized train) 8. , The output waveform is close to a sine wave with suppressed distortion.

As described above, according to this embodiment, the magnetic recording unit 1 facing the magnetic sensor 4 has the first magnetic stripe (main magnetic field) in which the N and S poles are alternately magnetized and recorded at a predetermined cycle T. Magnetizing train) 6 and the predetermined period T is T1, T
It is divided into three parts of 2 and T3, and the region of the period T2 at the center of the three parts is made into the non-magnetized portion 7, and the periods T1 on both sides are
Since the region of T3 has the second magnetic stripe (correction magnetized array) 8 magnetized to the same magnetic pole as the first magnetic stripe 6, the first magnetic stripe (main magnetized) is formed. The output waveform including the distortion from the magnetic train 6 is corrected by the output waveform from the second magnetic stripe (correction magnetizing train) 8, so that the magnetic recording unit 1 and the magnetic recording unit 1 can obtain stable output. Even if the spacing with the sensor 4 is set to be narrow, the output waveform of the magnetic sensor 4 is suppressed from being distorted and becomes close to a sine wave, so that it is possible to realize an encoder that enables highly accurate operation.

Thus, even in the case of a brushless motor, for example, F used as a control signal for rotating position, rotating speed, etc.
Since the G signal waveform is a wave close to an ideal sine wave, the magnetic signal input does not become small, the output fluctuation does not become small, and the inconvenience that the output waveform is wavy does not occur. Therefore, since stable and accurate servo can be applied, stable rotation at a constant speed can be obtained.

[0015]

According to the first aspect of the present invention, the first magnetic stripe in which the magnetic recording portion arranged to face the magnetic sensor is magnetized and recorded with N and S poles alternately at a predetermined interval. And the predetermined interval is divided into three, the central portion of the three divisions is a non-magnetized portion, and both sides are second magnetic stripes magnetized to the same pole as the magnetic pole of the first magnetic stripe. Since it is configured to have a stable output, even if the spacing between the magnetic recording unit and the magnetic sensor is set to be narrow, distortion of the output waveform of the magnetic sensor is suppressed and high-precision operation is possible. The encoder can be realized.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of an encoder of the present invention.

FIG. 2 is a magnetization pattern of a magnetic recording unit of the encoder of this embodiment.

FIG. 3 is an output waveform obtained from the first and second magnetic stripes of the magnetic recording unit of the encoder of this embodiment.

FIG. 4 is an output waveform obtained from the magnetic recording unit of the encoder of this embodiment.

FIG. 5 is an output waveform obtained from the magnetic recording unit of the encoder of this embodiment.

[Explanation of symbols]

 1 magnetic recording section 3 drum 4 magnetic sensor 5 magnetic resistor 6 first magnetic stripe (main magnetized row) 7 non-magnetized section 8 second magnetic stripe (correction magnetized row)

Claims (1)

[Claims] 1. An encoder in which a magnetic recording unit is arranged so as to face a magnetic sensor and outputs an electric signal according to a displacement due to relative movement of the magnetic recording unit and the magnetic sensor, wherein the magnetic recording unit has a predetermined interval. And the first magnetic stripe in which the N and S poles are alternately magnetized and recorded, and the above-mentioned predetermined interval is divided into three, and the central portion of these three divisions is a non-magnetized portion, and both sides are the above-mentioned first An encoder having a magnetic pole of a magnetic stripe and a second magnetic stripe magnetized to the same pole.