JPH09121589A - Linear motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the position of a moving body with high accuracy at a high speed by providing a band damping filter and mainly damping the signal component in the same band as that of the natural frequencies of the moving body, armature coils arranged on a stator, etc., from control signals or magnetic pole detecting signals. SOLUTION: An encoder section 24 recognizes the position of a moving body 6 based on a signal from a position reading-out section 22 provided on a moving body 6 which is constituted as the mover of a mobile coil type linear motor 2. A magnetic pole detecting section (Hall element) 18 detects the magnetic pole of a field magnet. A control section 26 finds a control signal based on a position signal and position command signal from an encoder section 24. A driving section 44 forms a driving current supplied to armature coils 14a-1c based on the control signal of the control section 26 and a magnetic pole detecting signal from the detecting section 18. A band damping filter section 42 damps the signal component in a frequency band which is substantially equal to the natural frequency of the motor 2 from the control signal and magnetic pole detecting signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motor, and more particularly to a linear motor drive circuit capable of high-speed and highly accurate positioning.

[0002]

2. Description of the Related Art Generally, for example, a linear motor is used in a robot, a multi-axis stage such as XY, or the like, because it is necessary to move an object at a high speed and accurately position the object. In this linear motor, a large number of armature coils are arranged in the stator and a movable magnet type in which a field magnet is mounted in the mover, and conversely, a large number of magnets are arranged in the stator and A moving coil type equipped with a child coil is known. The moving coil type linear motor may have a little inferior positioning accuracy due to the occurrence of natural vibration at a low frequency due to insufficient rigidity of the moving body, but on the other hand, since the thrust generating portion is lightweight, It is suitable for high speed and is widely used in various fields. Further, similar to the moving coil type linear motor, the moving magnet type linear motor also has the problem of the above-mentioned natural vibration, for example, in the armature coil portion on the stator side. Widely used in the field.

A moving coil type linear motor will be described with reference to FIGS. 8 and 9. 8 is a plan view showing a general moving coil type linear motor, and FIG. 9 is a plan view.
3 is a sectional view of the linear motor shown in FIG. As shown
The linear motor 2 is mainly composed of, for example, a stator 4 linearly extending for several meters and a moving body 6 as a mover that moves on the stator 4 along its longitudinal direction. This stator 4 is, for example, SS41 or SS400.
On the upper surface of the yoke 5 formed of carbon steel or the like,
A large number of field magnets 8 are arranged so that the N poles and the S poles are alternately arranged along the longitudinal direction thereof to form the magnetic gap 3. The field magnet 8 may be formed by magnetizing a single magnet with multiple poles or a plurality of magnets may be attached. In addition, the yoke 5 of the stator 4
A pair of guide rails 10 and 10 for guiding the moving body 6 are provided on both sides of the upper surface of the stator 4, and the yoke 5 of the stator 4 is provided.
An encoder scale 12 is formed on one side surface along the longitudinal direction thereof, and the position of the moving body 6 can be recognized by counting the scale of the scale 12 as described later.

The movable body 6 is provided with rollers 16 which can rotate on the guide rails 10 at its four corners, so that the movable body 6 can move. A plurality of, for example, three armature coils 14A, 14B, 14C facing the field magnet 8 are provided at the magnetic pole pitch P (width of two magnetic poles) of the field magnet 8 in the central portion of the lower surface of the moving body 6. In contrast, the electrical angle is 120 °
They are installed at different positions on a coil substrate (not shown). For example, when a phase-controlled three-phase alternating current is passed through the coil substrate, the generated magnetic field interacts with the magnetic field from the field magnet 8. The moving body 6 is moved in the direction A and stopped at a desired position.
The number of coils is not limited to three.

At the center of each armature coil 14A, 14B, 14C, for example, a Hall element 1 as a magnetic pole detecting means is provided.
8 (18A, 18B, 18C) are provided,
By these, the magnetic pole of the field magnet 8 is detected. In addition, the arm 20 extending from the moving body 6
An encoder position reading unit 22 is provided at the tip of the. The position reading section 22 is attached so as to face the scale 12, and the scale of the scale 12 can be read optically or magnetically. A light emitting element or a light receiving element is used in the case of the optical position reading section, and a Hall element or a magnetoresistive element is used in the case of the magnetic position reading section.

FIG. 10 shows a block diagram of the drive circuit of the linear motor. In the figure, the portion surrounded by the broken line shows the moving body 6. Now, in the above-mentioned configuration, the position reading section 22 outputs a signal in which the scale of the scale 12 is constantly read, and the hall element 18 outputs a magnetic pole detection signal. The read signal is input to the encoder section 24, and the position signal of the moving body 6 is obtained by counting signal pulses or the like. As the system of the encoder section 24, an incremental system, an absolute system or the like can be used.

The position signal obtained by the encoder unit 24 is compared with a position command signal input from, for example, a host computer (not shown) or the like in the control unit 26, and a control signal which eliminates the deviation between the two is generated. It is output via the / A converter 28. Upon receiving this control signal, the three-phase commutator unit 30 also receives the magnetic pole detection signal from the Hall element 18 to recognize the current state of the magnetic pole, and to move the moving body 6 in a direction to eliminate the above deviation. Controlled 3
Outputs phase alternating current. This three-phase alternating current is amplified by the amplifier 32 and is supplied as a drive signal to the armature coils 14A, 14B, 14C of the moving body 6 in a fixed direction until the deviation between the position signal and the position command signal becomes zero. Thrust is generated to move the moving body 6. That is,
During the traveling movement, the position signal constantly feeds back, and the movement is continued until this value becomes the same as the position command signal.

FIG. 11 shows a perspective view of a general movable magnet type linear motor. In the movable magnet type linear motor 2 ′ of FIG. 11, on the side of the stator 4, a large number of armatures are provided on a coil substrate 35 (for example, an insulating glass-containing epoxy resin substrate) provided on a base 37. Coil 14
Are arranged over the entire length of the traveling stroke of the moving body 6, and Hall elements 18 are respectively provided at the center positions of the armature coils 14. Rails 16 and 16 are provided at both ends of the upper surface of the base 37. Also,
An encoder scale 12 (not shown) is provided on one side surface of the base 37 along the moving direction of the moving body 6, and the position of the moving body 6 can be recognized by counting the scale of the scale 12. There is. Next, the armature coil 1 is provided on the moving body 6 side through a magnetic gap.
In the example shown in FIG. 11, the field magnet 8 arranged so as to face 4 is formed with six magnetic poles N and S in total, and is fixed to the yoke 5. Further, sliders 33 are respectively arranged on the projections at the four corners of the yoke 5, and the moving body 6 is guided and supported on the rails 16 and 16 by the four sliders 33, and the armature coil 14 (each coil Is installed on the coil substrate 35 by changing the magnetic pole pitch P of the field magnet 8, that is, the width of two magnetic poles by 120 ° in terms of electrical angle, and at the same time, the arbitrary armature coil 14A located in the magnetic gap. , 14B, 14C are supplied with a phase-controlled three-phase alternating current) and a magnetic field generated by the field magnet 8 interacts with each other to generate thrust in the moving body 6 and move in the B direction. It is configured to be possible. Further, the arm 20 extending from the moving body 6 is provided with a position reading unit 22 (not shown) of the encoder, as in the case of FIG. 9, and the position reading unit 22 is attached so as to face the scale 12 and is optically attached. The scale of the scale 12 can be read magnetically or magnetically.

The block diagram of the drive circuit of the general movable magnet type linear motor 2'of FIG.
The description is omitted because it is the same as the case of the moving coil type linear motor 2 (FIG. 10) except that the Hall element 18 and the Hall element 18 are arranged on the stator side.

[0010]

By the way, as with any object, the moving body of the moving coil type linear motor has its own mechanical frequency, that is, its natural frequency. There is no problem if the natural frequency is significantly different from the control frequency of the electric circuit system such as the drive signal, but if both frequencies are relatively close or the same, oscillation etc. However, there is a problem in that the positioning accuracy is deteriorated due to the occurrence of. That is, as described above, the position control of the moving body 6 is performed by the scale position reading unit 22.
Feedback is performed based on the read signal from the controller so that the deviation between this value and the position command signal from the host computer, etc. becomes zero, but the natural frequency of the moving body is the signal of the control system. If the frequency is close to the frequency, when the moving body is stopped, the feedback becomes unstable due to, for example, vibration, oscillation occurs, and the positioning accuracy deteriorates. Also in the moving magnet type linear motor, if the natural frequency of the armature coil on the moving body or the stator side is close to the signal frequency of the control system, the positioning accuracy deteriorates like the moving coil type linear motor. I will end up.

As a measure to solve such a problem, in a movable coil type linear motor, the rigidity of the entire moving body is increased by thickening the coil substrate to which the armature coil is attached, and the natural frequency is intentionally increased. It is conceivable to largely remove this from the frequency of the control system, but in this case, since the weight of the entire moving body becomes large, a moving coil type linear motor that is lightweight and has a high moving speed is used. It is not desirable because it suppresses the features.
Further, even in the movable magnet type linear motor, there is a problem that it is not possible to reduce the size and weight because the rigidity of the entire moving body or the stator to which the armature coil is attached is increased.

As a technique related to the present invention, Japanese Patent Application Laid-Open No. 4131/1992
In Japanese Patent No. 7589, a filter is connected in series to a Hall element as a magnet polarity detecting means, so that P
It is disclosed that an output signal having the same period as the WM drive period is removed to prevent a decrease in output thrust. However, this proposal is intended to prevent the current supply timing of the polarity switching control circuit that switches the direction of the current supplied to the exciting coil from being disrupted, and does not solve the problem caused by natural vibration. Therefore, it is not directly related to the present invention. The present invention has been made in view of the above problems, and has been devised to effectively solve them. An object of the present invention is to provide a linear motor that can perform high-speed and highly accurate positioning control.

[0013]

As a result of earnest research on oscillation during position control of a moving body, the present inventor suppresses this vibration by using a band attenuation filter tuned to the natural frequency of the moving body. The present invention has been achieved by obtaining the finding that it is possible. That is,
In the first aspect of the present invention, in order to solve the above-mentioned problems, a field magnet arranged on the stator side and an armature coil movably provided through this field magnet and a magnetic gap are provided. A moving coil type linear motor comprising a moving body having an encoder section for recognizing the position of the moving body based on a signal from a position reading section provided in the moving body, and a magnetic pole of the field magnet. A magnetic pole detection unit for detecting, a control unit that obtains a control signal based on a position signal and a position command signal from the encoder unit, and a control signal of this control unit and a magnetic pole detection signal from the magnetic pole detection unit. And a drive unit that forms a drive current to be supplied to the armature coil, and a frequency band that is substantially the same as the natural vibration frequency of the moving coil linear motor from the control signal or the magnetic pole detection signal. The signal component is obtained by constituting the linear motor to and a band attenuation filter unit for attenuating. Next, according to a second aspect of the present invention, an armature coil arranged on the stator side and a moving body having a field magnet movably provided through the armature coil and a magnetic gap are provided. And a magnetic pole detection for detecting a magnetic pole of the field magnet, which is a movable magnet type linear motor for recognizing a position of the moving body based on a signal from a position reading section provided in the moving body. Department,
A control unit that obtains a control signal based on a position signal and a position command signal from the encoder unit, and a drive that supplies the armature coil based on the control signal of the control unit and the magnetic pole detection signal from the magnetic pole detection unit. A drive that forms an electric current;
A linear motor is configured to include a band attenuation filter unit that attenuates a signal component in a frequency band substantially the same as the natural vibration frequency of the movable magnet type linear motor from the control signal or the magnetic pole detection signal.

With the above configuration, the encoder section outputs a position signal indicating the position of the moving body based on the signal from the position reading section, and this position signal is output from, for example, the host computer. The control command is compared with the position command signal and a control signal is output so that the deviation between the two is zero. Since this control signal may include a natural vibration frequency as a noise component, the control signal is passed through the band attenuation filter section of the present invention,
The noise component contained in this is attenuated and removed. Then, this output signal is supplied as a bias current of the magnetic pole detection unit including, for example, a Hall element. In this magnetic pole detection unit, a signal in which the change in the bias current and the change in the magnetic pole are synergistically expressed is output as an output signal, that is, a magnetic pole detection signal. The drive current in which the direction of the current supplied to the coil, that is, the phase of the current is controlled is output.

Therefore, since the noise component of the natural frequency contained in the control signal is attenuated and removed by the band attenuation filter section of the present invention, the noise component does not ride on the drive signal, and the vibration is generated by the noise component. Therefore, the positioning accuracy can be improved. By configuring this filter section as an analog filter,
Compared with the case where it is configured as a digital filter, calculation by software is unnecessary, and accordingly, quick control is possible. Further, by making the attenuation frequency band of the band attenuation filter unit variable, it is possible to deal with armature coils mainly having a different natural frequency and arranged in a moving body or a stator.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An example of an embodiment of a drive circuit applicable to a linear motor of the present invention will be described in detail below with reference to the accompanying drawings. 1 is a block diagram showing a drive circuit applicable to a moving coil type linear motor of the present invention, FIG.
3 is a diagram showing a main part of the circuit in FIG. 1, and FIG. 3 is a circuit configuration diagram showing a band attenuation filter unit used in the circuit shown in FIG.
The same parts as those of the conventional structure described above will be designated by the same reference numerals.

A portion surrounded by a broken line in FIG. 1 shows a moving body 6 as a mover of the moving coil type linear motor 2, and this linear motor 2 is the same as that shown in FIG. Since it is configured, its detailed description is omitted here. As shown in FIG. 8, the moving body 6 naturally includes a plurality of armature coils 14A, 14B, 14C arranged in order along the moving direction and a scale 1.
A position reading section 22 for optically or magnetically reading the second scale and a Hall element 18 (18A, 18B, 18A, 18B, etc.) as a magnetic pole detecting section for detecting the magnetic pole of the field magnet 8.
18C). When four or more armature coils are provided, it goes without saying that coils that are electrically in phase are commonly connected.

The encoder section 24 includes the position reading section 2
The number of signal pulses is counted based on the read signal output from 2 to obtain the position of the moving body 6 on the stator 4, and the obtained position signal is supplied to the control unit 26.
The control unit 26 controls the entire circuit,
For example, it is configured by a microcomputer or the like, and is connected to a ROM 34 in which a program representing the entire control operation is stored in advance, a RAM 36 for writing and storing information during processing.

A position command signal from, for example, a host computer (not shown) is manually input to the control unit 26 via, for example, an interface 38, and the control unit 26 calculates a deviation between the position command signal and the position signal. Asked in
The control signal is output so that the deviation between the two is eliminated. The D / A converter 40 converts the control signal from a digital signal to an analog signal, and outputs the analog control signal to the band attenuation filter unit 42 which is a feature of the present invention. The band attenuation filter unit 42 attenuates a signal in the same frequency band as the natural frequency of the moving body 6 included in the control signal, for example, a signal in the vicinity of 800 Hz, as will be described later. It is adapted to be supplied as a bias current of the element 18.

The drive section 44 switches the current based on the magnetic pole detection signal supplied from the Hall element 18 to drive three phases of U, V and W phases which are 120 ° out of phase in electrical angle. Form an electric current. Specifically, as shown in FIG. 2, the drive section 44 includes Hall elements 18A and 18A.
A three-phase commutator unit 46 that forms a three-phase current by switching the direction of the current based on the magnetic pole detection signals from H and 18C.
And a power amplifier 48 that amplifies the three-phase current to form a drive current. Although only one Hall element is shown in FIG. 1, in reality, at least three Hall elements 18A, 18B and 18C are provided corresponding to three-phase alternating current as described in FIGS. 8 and 2. Therefore, the bias side of each Hall element is connected in series, and the control signal from the band attenuating filter unit 42 is supplied as a bias current through the input resistor 50 having a predetermined value.

The band attenuating filter section 42 is constructed by using, for example, two amplifiers 52A and 52B as shown in FIG. 3, and one amplifier 52A has a low-pass filter 54 and a variable-pass filter 54 for cutting a wide range frequency at its ten terminal. A control signal is input via the resistor R1, and the output signal from this amplifier is fed back to one input terminal. Also,
This amplifier 52A has a variable capacitor C on its terminal side.
It is connected via 1 to the ten input terminal of the other amplifier 52B, and the output signal of this amplifier 52B is also fed back to this one input terminal. Further, the latter power terminal of the amplifier 52B is grounded via the variable resistors R2 and R3, and the connection point between the resistors R2 and R3 is connected to the output side of the amplifier 52B via the variable capacitor C2. These are connected, and with this configuration, a signal having a frequency component substantially the same as the natural frequency of the moving body 6 can be attenuated.

As the amplifiers 52A and 52B, for example, an operational amplifier TL072 is used, and each reversible resistance R1,
The values of R2 and R3 are, for example, 22 kΩ and 3.3 k, respectively.
Ω, 3.3kΩ, and each variable capacitor C
The capacitances of 1 and C2 are, for example, 4.7 nF and 0.6, respectively.
It is set to 9 μF, and a signal of about 850 Hz is trapped at an attenuation rate of about 13 dB, and the Q value (value that is a guide for filter performance) at that time is 6.

Next, the operation of the present embodiment configured as described above will be described. First, according to the traveling movement of the moving body 6, the position reading section 22 provided in the moving body 6 outputs a read signal obtained by reading the scale of the scale 12, and this signal is counted by the encoder section 24 to detect the current state of the moving body 6. The position is always known. The position signal obtained by the encoder unit 24 is supplied to the control unit 26, where the deviation between the position command signal and the position signal input from the host computer or the like is calculated, and the deviation is eliminated. A control signal is output to move the moving body 6.

Since this control signal is a digital signal, it is converted into an analog signal by the D / A converter 40 and then passed through the band attenuation filter section 42 to be used as the bias current of the Hall element 18 constituting the magnetic pole detection section. It is supplied and is adapted to vary this sensitivity. In the Hall element 18, a change in the field magnet magnetic field due to the movement of the moving body 6 is detected and a magnetic pole detection signal is output.
This magnitude is naturally affected by the magnitude of the bias current, that is, the magnitude of the control signal, and as a result, a change in bias current and a change in magnetic pole are output synergistically as a magnetic pole detection signal.

Based on this magnetic pole detection signal, the three-phase communicator section 46 of the drive section 44 is phase-controlled U so as to move the moving body 6 in a direction to eliminate the above-mentioned deviation.
The V-phase and W-phase three-phase currents are formed, and the three-phase currents are power-amplified by the power amplifier 48, respectively, and corresponding armature coils 14A, 14B, 14 are provided as drive signals.
Will be supplied to C. Then, the interaction between the magnetic field generated by each armature coil and the magnetic field from the field magnet 8 of the stator 4 causes thrust to be generated in the moving body 6 to travel to a desired position.

Now, during such control operation,
The excitation band frequency of the servo control of the moving coil linear motor 2 is usually about 200 to 300 Hz, and this frequency is very close to the natural frequency of the moving body 6, for example, 850 Hz. There is a tendency for vibration to cause resonance. In particular, this resonance phenomenon greatly appears when the moving body 6 is stopped, which causes deterioration of the positioning accuracy. This resonance phenomenon becomes noise and is included in the position signal detected by the encoder unit 24, and also affects the drive signal by the feedback, so that the vibration tends to be further enhanced.

However, in the present embodiment in which the configuration of FIG. 1 is applied to the moving coil type linear motor 2, the signal in the band substantially the same as the natural frequency contained in the control signal is attenuated at the subsequent stage of the control unit 26. Since the band attenuating filter unit 42 is provided, this signal component is attenuated or removed, and therefore, the drive signal contains almost no frequency component substantially the same as the natural frequency, so that the moving body 6 resonates. Can be prevented. That is, as shown in FIGS. 2 and 3, the analogized control signal is as follows.
After the high-pass frequency of, for example, 3.4 kHz or more is cut by the low-pass filter 54, the two amplifiers 52A,
A filter unit formed by combining 52B, for example, 850H
The signal components in the frequency band near z are attenuated, and three output control signals are connected in series to the hall elements 18A, 1A.
It is supplied as a bias current of 8B and 18C.

Therefore, the signal component corresponding to the natural vibration frequency contained in the magnetic pole detection signal which is the output signal of each Hall element is suppressed, and as a result, the resonance of the moving body 6 is eliminated as described above. be able to. Therefore, as compared with the conventional device, it is possible to significantly improve the positioning accuracy when the moving body is stopped.

Next, the result of comparison between the case where the present invention is applied and the conventional case in the moving coil type linear motor will be described. FIG. 4 shows the input / output transfer characteristics when the above-mentioned values are applied as the values of the variable resistors R1 to R3 and the capacitors C1 and C2 of the band attenuation filter unit 42 shown in FIG. Corresponding to the natural frequency of the moving body 6 in the moving coil type linear motor 2 to which the configuration is applied, it is set to exhibit an attenuation rate of 13 dB when the frequency is approximately 850 Hz. FIG. 5 is a graph showing the amplitude characteristic measurement results of the moving body 6 in the moving coil linear motor 2 with and without the band attenuation filter 42 having such characteristics. In the case of the conventional moving coil type linear motor in which the band attenuation filter unit 42 is not provided, a large peak occurs due to natural vibration near 850 Hz, but in the case of the present invention in which the band attenuation filter unit 42 is provided, Especially frequency 850H
At 600 Hz to 1 kHz centering on z, the peak value of the natural frequency was attenuated by 3 to 13 dB, and it was found that the vibration suppressing effect of the moving body 6 was sufficiently exerted.

In this embodiment, the case where the natural frequency of the moving body is 850 Hz has been described as an example. However, the natural frequency may vary depending on the type of the moving body 6, and 850
It is not limited to Hz. Then, in this case, the variable resistors R1 to R1 configuring the band attenuation filter unit 42 are
The damping frequency band may be matched with its natural frequency by appropriately adjusting the resistance value of R3 and the capacitance values of the variable capacitors C1 and C2 to change the time constant. Further, in this embodiment, as shown in FIG. 2, the Hall elements 18A, 18B, 1
Since the bias electrode of 8C is connected in series and the control signal is passed through the bias electrode, only one band attenuation filter unit 42 needs to be provided, and the filter unit 42 is mainly composed of two operational amplifiers. Since it can be done, the cost does not have to be increased.

Further, it is conceivable that the control function of the band attenuation filter section 42 is digitally processed by the control section 26 by software. In this case, the control section 26 is used.
Not only becomes too heavy, but also the processing time becomes considerably long, and there is a possibility that quick control cannot be performed. On the other hand, in the present invention, the band attenuation filter unit 42 is configured as an analog filter. Therefore, the control time can be secured without causing a delay in the processing time. Although the bias electrodes of the Hall element are connected in series in the above embodiment, the present invention is not limited to this, and they may be connected in parallel as shown in FIG. In this case, the control signal output from the band attenuation filter unit 42 is set to 3
It may be branched into three and supplied in parallel to the bias electrodes of the Hall elements 18A, 18B and 18C. In this way, when the bias electrodes are connected in parallel, the input resistors 50, 50, 50 are interposed in each branch circuit.

In the present embodiment, the band attenuation filter section 42 is provided on the bias electrode side of the Hall element to remove the natural vibration frequency component contained in the control signal. Each Hall element 18 as shown
A band attenuation filter unit 42 may be interposed on the output side of each of A, 18B, and 18C to remove the natural vibration frequency component included in the magnetic pole detection signal. Further, the case where the Hall element is used as the magnetic pole detection unit has been described as an example, but the present invention is not limited to this, and it goes without saying that a magnetoresistive effect element, an optical detection element, or the like can also be used.

Next, when the vibration characteristics of the conventional moving magnet type linear motor 2 '(FIG. 11) equipped with the conventional linear motor drive circuit (FIG. 10) were measured, the moving coil type linear motor of FIG. 5 was obtained. Band attenuation filter unit 4
Similar to the case where 2 is not provided, a large peak near the frequency of 850 Hz due to natural vibration was generated in the armature coil 14 portion on the stator 4 side of the movable magnet type linear motor 2 '. Therefore, this conventional movable magnet type linear motor 2 '
(FIG. 11) The linear motor drive circuit of the present invention (FIG. 1)
, And the vibration characteristics were evaluated in the same manner as above,
It was confirmed that the band attenuation filter unit 42 attenuated a large peak near the frequency of 850 Hz, and the vibration suppressing effect of the armature coil 14 portion on the stator 4 side was sufficiently exerted. Here, the attenuation rate by the band attenuation filter unit 42 is 600 Hz to 1 k centering on a frequency of 850 Hz.
It was confirmed that the peak value of the natural frequency was attenuated by 3 to 13 dB at Hz. As described above, by providing the band attenuation filter unit 42 in the drive circuit of the movable magnet type linear motor 2 ′ as well, the movable magnet type linear motor 2 ′ can be effectively applied to the moving body 6, but mainly of the armature coil 14 portion on the stator 4 side. It was confirmed that the vibration suppressing effect was sufficiently exerted.

[0034]

As described above, according to the linear motor of the present invention, the following excellent operational effects can be exhibited. Since the band attenuation filter unit is provided to attenuate the signal component in the same band as the natural vibration frequency of the armature coil or the like mainly arranged in the moving body or the stator from the control signal or the magnetic pole detection signal, It is possible to suppress resonance of the armature coil or the like mainly arranged in the moving body or the stator. Therefore, highly accurate positioning operation can be performed.

Further, the analog configuration of the filter section makes it possible to secure a high-speed control operation without a time delay, unlike the case where the same function is achieved by software with a digital filter, for example. Furthermore,
By making the time constant of the filter part variable, it is possible to update the damping frequency band in correspondence with moving coil type and moving magnet type linear motors having different natural frequencies.

[Brief description of the drawings]

FIG. 1 is a block configuration diagram showing a drive circuit of a linear motor of the present invention.

FIG. 2 is a diagram showing a main part of a circuit in FIG.

FIG. 3 is a circuit configuration diagram showing a band attenuation filter unit used in the circuit shown in FIG.

FIG. 4 is a graph showing input / output transfer characteristics of a band attenuation filter unit.

FIG. 5 is a graph showing a result of comparison between a case where the band reduction filter unit having the characteristics shown in FIG. 4 is used and a conventional case.

FIG. 6 is a diagram showing a modification of the linear motor drive circuit of the present invention.

FIG. 7 is a diagram showing another modification of the linear motor drive circuit of the present invention.

FIG. 8 is a plan view showing a general moving coil type linear motor.

9 is a cross-sectional view of the linear motor shown in FIG.

FIG. 10 is a block diagram showing a conventional linear motor drive circuit.

FIG. 11 is a perspective view showing a general movable magnet type linear motor.

[Explanation of symbols]

2, 2'linear motor, 3 magnetic air gap, 4 stator,
5 yokes, 6 moving bodies, 8 field magnets, 12
Scale, 14, 14A, 14B, 14C Armature coil, 18, 18A, 18B, 18C Hall element (magnetic pole detection section), 22 Position reading section, 24 Encoder section, 26 Control section, 42 Band attenuation filter section, 44
Drive unit, 46 3-phase commutator unit, 48 power amplification unit, 52A, 52B amplifier, 54 low-pass filter

Claims (7)

[Claims] 1. A moving coil type linear motor comprising a field magnet arranged on the stator side and a moving body having an armature coil movably provided through the field magnet and a magnetic gap. There, an encoder unit for recognizing the position of the moving body based on a signal from a position reading unit provided in the moving body, a magnetic pole detecting unit for detecting the magnetic pole of the field magnet, and the encoder unit A control unit for obtaining a control signal based on the position signal and the position command signal, and a drive current to be supplied to the armature coil based on the control signal from the control unit and the magnetic pole detection signal from the magnetic pole detection unit. A drive unit and a band attenuation filter for attenuating a signal component in a frequency band substantially the same as the natural vibration frequency of the moving coil linear motor from the control signal or the magnetic pole detection signal. Linear motor is characterized in that a part. 2. An armature coil arranged on the stator side,
A movable magnet type linear motor comprising this armature coil and a moving body having a field magnet movably provided via a magnetic gap, the moving magnet type linear motor being based on a signal from a position reading section provided in the moving body. Encoder for recognizing the position of the moving body, a magnetic pole detector for detecting a magnetic pole of the field magnet, and a controller for obtaining a control signal based on a position signal and a position command signal from the encoder unit. A drive unit that forms a drive current to be supplied to the armature coil based on a control signal of the control unit and a magnetic pole detection signal from the magnetic pole detection unit; and a movable magnet linear unit based on the control signal or the magnetic pole detection signal. A linear motor comprising: a band attenuation filter unit that attenuates a signal component in a frequency band substantially the same as a natural vibration frequency of the motor. 3. The linear motor according to claim 1, wherein the band attenuation filter unit is an analog filter. 4. The linear motor according to claim 1, wherein the magnetic pole detector is formed of a Hall element. 5. The linear motor according to claim 4, wherein the drive signal is influenced by using the control signal as a bias current of the Hall element. 6. The linear motor according to claim 1, wherein the drive unit includes a three-phase commutator unit and a power amplification unit. 7. The linear motor according to claim 1, wherein an attenuation frequency band of the band attenuation filter unit is variable.