JPH0436613A - Magnetic rotary encoder - Google Patents

Abstract

PURPOSE:To provide both a detecting function for the angle of rotation of the rotary shaft of a servo motor and a detecting function for the magnetic pole position of the rotor together by recording magnetic information for detecting the angle of rotation and magnetic information for detecting a magnetic position on a common magnetic medium. CONSTITUTION:Magnetized part Y and unmagnetized parts N are provided alternately on respective tracks Tu, Tv, and Tw of the magnetic recording medium 1 at intervals of 90 deg. by dividing the entire circumference, i.e. 360 deg. equally into four; and the magnetized patterns on the V-phase track Tv are 60 deg. out of phase with the magnetized patterns on the U-phase track Tu and the magnetized patterns on the W-phase track Tw are 60 deg. out of phase with the magnetized patterns on the V-phase track Tv. A magnetic sensor unit 15 has six magneto-resistance elements formed on a glass substrate and is arranged opposite the outer peripheral surface of the magnetic recording medium 1 across a constant gap. Further, the magneto-resistance elements Ru, Rv, and Rw are arranged opposite the respective tracks Tu, Tv, and Tw of U, V, and W phases. Consequently, the rotational angle detecting function for the rotary shaft of the servo motor and magnetic position detecting function for the rotor are both provided together.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic rotary encoder suitable for application to an AC servo motor used as a drive source for various FA (factory automation) equipment.

"Prior Art" FIG. 4 is a diagram showing the configuration of a conventional magnetic rotary encoder. In this figure, ■ is a disc-shaped magnetic recording medium, and a shaft 2 is attached to this magnetic recording medium 1, and this shaft 2 is supported rotatably in the direction of arrow M by a bearing (not shown) or the like. . An origin track Tz and a pitch signal track Tp are provided in parallel over the entire circumference of the outer peripheral surface of the magnetic recording medium l.

In this origin track Tz, half a cycle of sinusoidal magnetic information is recorded as an origin signal at the origin of the magnetic recording medium l, and in the pitch signal track Tp, a signal of a constant wavelength λ is recorded. It has been sine. 4 and 5a
, 5b is a magnetic sensor formed by forming a magnetoresistive element on a glass substrate, and is a magnetic recording medium! are placed opposite to each other with a certain gap between them. The above-mentioned magnetoresistive element is composed of an element material that produces a so-called magnetoresistive effect, a phenomenon in which specific resistance changes depending on the strength of the magnetic field when placed in a magnetic field. Then, the origin signal recorded on the origin track Tz and the pitch signal recorded on the pitch signal track Tp are read.Furthermore, the magnetic sensor 5a
and 5b are spaced apart from each other by Cm 174)λ (where m is an integer) along the moving direction M of the magnetic recording medium 1, and are arranged facing the pitch signal track Tp. The resistance value of the magnetoresistive element patterns of the magnetic sensors 5a and 5b changes depending on the magnetic field received from the pitch signal track Tp. It is possible to obtain a level signal. That is, if the section of one period of sinusoidal magnetic information on the pitch signal track TI is θ-〇~2π, then the magnetic sensor 5a
A level signal of sin θ is obtained from the magnetic sensor 5b, and a level signal of COS θ is obtained from the magnetic sensor 5b. When the pitch signal track Tp moves relative to the magnetic sensors 5a and 5b, two-phase detection signals sinθ (phase A) and COSθ(B
phase) is obtained.

Further, reference numeral 6 denotes an angle detection circuit, which is composed of waveform shaping circuits 7, 8 and 9, a direction determining circuit 10, and an up/down counter 11. Waveform shaping circuits 7 and 8
Here, the A-phase and B-phase detection signals are waveform-shaped and output. In this case, the A-phase pulse Pa and the B-phase pulse Pb output from the waveform shaping circuits 7 and 8 respectively become rectangular waves whose phases are shifted by π/2, and when the rotation direction of the magnetic recording medium l is in the positive direction, , the A-phase pulse Pa has an advanced phase, and in the case of a negative direction, the B-phase pulse Pb has an advanced phase. In the direction discrimination circuit IO, for example, at the rising edge of the A-phase pulse Pa, the B-phase pulse pb
The direction of rotation is determined depending on whether the level is "H" or "L". The output signal S- of the direction determining circuit 1O is supplied to the up/down switching terminal U/f of the counter 11.

The counter 11 counts the A-phase pulses Pa while the count mode is switched up or down by the signal Sv. In this case, magnetic recording medium 1
When the wheel is rotating in the positive direction, an up count is performed, and when the wheel is rotating in the negative direction, a down count is performed.

On the other hand, each time the origin of the magnetic recording medium 1 passes through the location where the magnetic sensor 4 is installed, the magnetic sensor 4 detects the origin signal recorded at the origin, and this is transmitted through the waveform shaping circuit 9 to the origin pulse Pz. and is supplied to the reset terminal R of the counter 11. As a result,
The counter 11 is reset each time the origin of the magnetic recording medium l reaches the installation location of the magnetic sensor 4. Therefore,
The count value of the counter 11 indicates the magnetization of the pitch signal track Tp that has passed over the magnetic sensors 5a and 5b from the time when the origin of the magnetic recording medium l passed through the installation location of the magnetic sensor 4 until the present time. The value corresponds to the number of intervals. That is, the count value corresponds to the rotation angle of the magnetic recording medium l. Then, a value is outputted to the counter II as detected angle data D corresponding to the rotation angle of the shaft 2.

"Problem to be Solved by the Invention" By the way, the above-mentioned magnetic rotary encoder is used for detecting the angle of each motion axis of an industrial robot, etc.
In this case, the shaft 2 of the magnetic rotary encoder described above is directly connected to the rotating shaft of the motor that drives each operating shaft.

On the other hand, industrial robots installed in explosive atmospheres such as paint factories are required to have an explosion-proof structure, and industrial robots installed in extremely clean workplaces such as semiconductor manufacturing facilities are required to be protected against dust. It is necessary to suppress the occurrence as much as possible. For this reason, AC servo motors, which have a brushless structure and can fully meet the above requirements, are used as motors for driving each operating axis of this type of industrial robot. To control this AC servo motor, an fM magnetic pole position detector for detecting the position of the magnetic pole of the rotor is essential, and a resolver or the like is incorporated as this magnetic pole position detector. In this case, the magnetic rotary encoder for angle detection described above does not have the function of outputting a signal according to the magnetic pole position of the rotor of the motor, so the magnetic rotary encoder for angle detection described above is placed on the rotation axis of the motor. The magnetic rotary encoder and the magnetic pole position detector have to be assembled separately, which results in the problem that a large occupied space must be secured and maintenance and inspection are complicated.

This invention was made in view of the above-mentioned circumstances, and
It is an object of the present invention to provide a magnetic rotary encoder that is provided with a magnetic pole position detection function that detects the magnetic pole position of the rotor of this motor in addition to an angle detection function that detects the rotation angle of the rotating shaft of a servo motor.

"Means for Solving the Problems" The present invention reads magnetic information pre-recorded on a rotatably supported magnetic recording medium, thereby controlling the rotating shaft of an AC servo motor connected to the magnetic recording medium. In a magnetic rotary encoder that detects rotation angle,
A magnetic pole position detecting device provided on the magnetic recording medium and comprising a magnetized part on which magnetic information is recorded corresponding to the magnetic pole position of the rotor of the AC servo motor and an unmagnetized part on which no magnetic information is recorded. track, and detection means for detecting the presence or absence of magnetic information on the magnetic pole position detection track and outputting a signal corresponding to the magnetic pole position of the rotor of the AC servo motor based on the presence or absence of the magnetic information. It is characterized by

"Operation" According to the above configuration, the magnetic information for detecting the rotation angle of the rotating shaft of the AC servo motor and the magnetic information for detecting the magnetic pole position of the rotor of this motor are stored on a common magnetic recording medium. This allows the magnetic recording medium to be shared.

"Example" Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing the mechanical configuration of an embodiment of the present invention. In this figure, the outer peripheral surface of the magnetic recording medium l has a pitch signal track Tp, an origin track Tz, a U-phase track Tu, and a V-phase track T over its entire circumference.
V and a W-phase track Tw are provided. In the origin track Tz, half a cycle of sinusoidal magnetic information is recorded as an origin signal at the origin of the magnetic recording medium l, as in the past, and in the pitch signal track TI) , as in the past, sinusoidal magnetic information with a constant wavelength λ is repeatedly recorded as a pitch signal. Furthermore, each track Tu, Tv, Tl of U phase, ■ phase, W phase
, there is a magnetized part Y in which magnetic information of a predetermined wavelength is recorded corresponding to the magnetic pole position of an AC servo motor rotor (not shown) connected to the shaft 2, and an unmagnetized part N in which no magnetic information is recorded. are provided for each. In this case, each track T
For u, Tv, and Tw, as shown in Figure 3 (a), (b), and (c), there are magnetized parts Y and unmagnetized parts N at every 90°, which is obtained by dividing the entire circumference of 360° into four equal parts. They are provided alternately, and the magnetization pattern of the V-phase track Tv is 60° out of phase with the magnetization pattern of the U-phase track Tu.
The phase of the magnetization pattern of the W-phase track Tw is shifted by 60° with respect to the magnetization pattern of .

On the other hand, reference numeral I5 shown in FIG. 1 is a magnetic sensor unit formed by forming six magnetoresistive elements on a glass substrate, and is arranged facing the outer circumferential surface of the magnetic recording medium l with a certain gap therebetween. There is. This magnetic sensor unit 15 includes
Conventional magnetic sensors 4 and 5 a, 5 shown in FIG.
In addition to the magnetoresistive element corresponding to b, there are U-phase, ■-phase, and W-phase tracks Tu.

Magnetoresistive elements Ru, Rv, and Rv are provided to face Tv and Tw, respectively.

Next, referring to FIG. 2, the electrical configuration of an embodiment of the present invention will be described. In FIG. 2, the magnetoresistive element R
u, Rv, and Rw are connected in series, and the magnetoresistive element R
One end of u is connected to power supply voltage +Vcc, the other end is connected to one end of magnetoresistive element Rw via magnetoresistive element Rv, and the other end of this magnetoresistive element Rw is grounded.

R1, Ry, and Rff are balance resistors connected in series, and one end of the resistor R1 is connected to the power supply voltage +Vcc,
The other end is connected to one end of the magnet R5 via a resistor R7, and the other end of this resistor R3 is grounded. These magnetoresistive elements Ru, Rv, Rw and balance resistors R5, R*
, R3 are suitably set so that they have substantially the same value in a state where they are not influenced by an external magnetic field, thereby forming a type of bridge circuit. In addition, 20 is a constant voltage signal obtained at the connection point of resistors R and R2,
A differential amplifier 21 non-inverting amplifies the difference between the voltage signal Sl obtained at the connection point of the magnetoresistive elements Ru and Rv and outputs it as a signal S, 21 is a constant voltage signal obtained at the connection point of the resistors R and R1. This is a differential amplifier that inverts and amplifies the difference between the voltage signal S obtained at the connection point between the magnetoresistive elements Rv and Rw, and outputs the resultant signal as a signal S4. These signals S.

and 84 are a voltage signal synthesized by series-connected resistors R4 and R6 and obtained at the connection point of resistors R4 and R6, and a constant voltage signal obtained by dividing the power supply voltage +Vcc by resistors R, , R, The difference between them is inverted and amplified by the differential amplifier 22, and output as a signal S. These function as adders that add and invert signals S3 and 64. Comparators 23, 24, and 25 output a constant voltage threshold level SL obtained by dividing the power supply voltage +Vcc by resistors Rs and Ra, and a signal S3. The voltages S % and S 2 are compared with each other, and the comparison results are output as a U-phase signal Su, a V-phase signal Sv, and a W-phase signal Sw. In this case, each comparator 23, 24.25 has a signal s a, s,
, s becomes larger than the threshold level SL, the U-phase signal Su, V-phase signal Sv, and W-phase signal Sw are set to "H" level, and when the voltage becomes smaller, the U-phase signal Su, V-phase signal Sv, and W-phase signal Sv, respectively.
level.

The operation of the embodiment configured as described above will be explained with reference to FIGS.

First, each track Tu, Tv, and Tw of the U phase, ■ phase, and W phase of the magnetic recording medium l is shown in FIG.
: As shown, magnetized portions Y and non-magnetized portions N are provided alternately every 90 degrees, and the phases are sequentially shifted by 60 degrees. As the magnetic recording medium 1 rotates, the voltage signal S+- obtained at the connection point between the magnetoresistive elements Ru and Rv changes as shown in FIG. 3(d).
The voltage signal S2 obtained at the connection point between the magnetoresistive elements Rv and RW changes as shown in FIG. 3 (e). Then, the voltage signal S is non-invertingly amplified by the differential amplifier 20 to become the signal S shown in FIG.
is inverted and amplified by the differential amplifier 21, and the result is shown in Fig. 3 (G).
The signal S4 shown in FIG. In addition, the signal S and 64 are connected to the resistor R
4R@ and the differential amplifier 22, and is further inverted to become the signal S5 shown in FIG. 3 (H).

These signals S s, S s, S 4 and the power supply voltage +
The threshold level SL obtained by dividing Vcc by the resistors R* and R* is determined by the comparator 23.2.
4.25, and the comparison results are output as a U-phase signal Su, a V-phase signal Sv, and a W-phase signal Sv. Here, U phase, ■ phase, W phase signals Su, Sv, Sv
corresponds to the presence or absence of magnetization of each track Tu, Tv, Tw of the magnetic recording medium l, and therefore corresponds to the magnetic pole position of the AC servo motor rotor shown in the figure connected to the shaft 2. There will be.

In the above-mentioned embodiment, by appropriately changing the range of the magnetized part Y and the non-magnetized part N of each track Tu, Tv, and Tw of the U-phase, ■-phase, and W-phase, it is possible to You can respond freely.

"Effects of the Invention" As explained above, according to the present invention, magnetic information for detecting the rotation angle of the rotation shaft of the AC servo motor;
The magnetic information for detecting the magnetic pole position of the rotor of this motor is recorded on a common magnetic recording medium, and by sharing the magnetic recording medium in this way, it is possible to Compared to the case where a magnetic rotary encoder and a magnetic pole position detector were installed separately, the space taken up is smaller, maintenance and inspection can be performed simultaneously and easily, and the inertia The advantage is that the moment can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the mechanical configuration of an embodiment of the present invention, FIG. 2 is a block diagram showing the electrical configuration of the embodiment, and FIG. 3 is a waveform diagram for explaining the operation of the embodiment. 4 are block diagrams showing the configuration of a conventional magnetic rotary encoder. 1... Magnetic recording medium, 15... Magnetic sensor unit, Tu...
・U phase track (magnetic pole detection track), Tv...
・・V phase track (magnetic pole detection track), Tw...
...W-phase track (magnetic pole detection track), Ru, R
v, Rw... Magnetoresistive element, R1 to R0...
...Resistance, 20.21.22...Differential amplifier, 23.24
．． 25...Comparator.

Claims (1)

[Claims] A magnetic rotary device that detects the rotation angle of a rotating shaft of an AC servo motor connected to a magnetic recording medium by reading magnetic information prerecorded on a rotatably supported magnetic recording medium. In the encoder, a magnetic pole is provided on the magnetic recording medium and includes a magnetized part on which magnetic information is recorded corresponding to the magnetic pole position of the rotor of the AC servo motor, and an unmagnetized part on which no magnetic information is recorded. A detection means for detecting the presence or absence of magnetic information on the position detection track and the magnetic pole position detection track, and outputting a signal corresponding to the magnetic pole position of the rotor of the AC servo motor based on the presence or absence of the magnetic information. A magnetic rotary encoder comprising: