JP4348620B2 - XY stage - Google Patents

Description

  The present invention controls the movement of the slider in the X-axis direction or the Y-axis direction by an AC current supplied to the X-axis motor and the Y-axis motor, and sets the AC current commutation phase angle corresponding to the X-axis and Y-axis positions. The present invention relates to an XY stage that suppresses a ripple caused by a cogging thrust generated in the slider by a cogging correction signal calculated based thereon.

  Patent Documents 1 and 2 detail the structure of an XY stage having a grating platen and a slider whose position is controlled by sliding the upper surface of the grating platen in the X-axis direction and the Y-axis direction and the technology for suppressing rotation around the Z-axis. It is disclosed.

JP 2000-65970 A

JP 2001-125648 A

  Conventionally, an XY stage position control having ripple suppression means for suppressing ripples caused by cogging thrust generated in the slider by a cogging correction signal calculated based on the commutation phase angle of the alternating current corresponding to the X-axis and Y-axis positions. There is a system. FIG. 3 shows such an XY stage position control system. FIG. 3 shows functional blocks for the X axis.

  In FIG. 3, reference numeral 1 denotes a slider having X-axis motors 11 and 12 and Y-axis motors 13 and 14 arranged diagonally. The Y-axis motors 13 and 14 are connected in series to control the Y-axis movement, but the X-axis motors 11 and 12 are individually operated to suppress the X-axis movement control and the rotation (yawing) around the Z-axis. Control.

  Reference numeral 2 denotes a position sensor which detects the X position, Y position, and rotation angle θ around the Z axis of the slider 1 on the lattice platen. The specific configuration of the position sensor is not described in detail because an example of a sensor using light interference is disclosed in Patent Document 1 in detail.

  A speed converter 3 calculates the speed of the slider 1 from the signal component of the X-axis position detection value Pfx, and calculates the speed detection value Vfx. Details of this speed converter are also disclosed in Japanese Patent Application Laid-Open No. H10-228707, and description thereof is omitted.

  Reference numeral 4 denotes a position control unit which calculates the deviation between the position command value Psx and the position detection value Pfx and outputs a speed command value Vsx. A speed control unit 5 calculates a deviation evx between the speed command value Vsx and the speed detection value Vfx and outputs a thrust command value Fdx.

  Reference numeral 6 denotes a thrust generator, which inputs a thrust command value Fdx and a cogging correction signal Fex from a ripple suppression means 8 (described later) that is added to the command value by an adding means 7 to input an X-axis motor and a Y-axis motor of the slider 1. Is supplied with an alternating current to generate a thrust Fx in the X-axis direction. Since details of this thrust generation unit are also disclosed in Patent Document 1, description thereof will be omitted.

  The X-axis motor and the Y-axis motor provided on the slider 1 are so-called that generates an thrust between the grid platen by supplying an alternating current to a plurality of cores opposed to the grooves of the grid platen formed of a magnetic material. Hybrid surface motors are advantageous in terms of responsiveness and cost and are often used.

  As a drawback of the hybrid type surface motor, there is a problem that a ripple is superimposed on the position control of the slider 1 by the cogging thrust Frx generated at every tooth pitch of the motor, that is, in synchronization with the commutation cycle of the alternating current supplied to the motor. This is one of the factors that reduce the accuracy of position control.

  A dotted line block 8 is a ripple suppression means according to the prior art, which calculates a cogging correction signal Fex having the same amplitude as the cogging thrust and an antiphase, and adding it to the thrust command value Fdx by the adding means 7, thereby generating the cogging thrust Frx. Suppress.

In the ripple suppression means 8, 81 is a commutation phase detection means. For the X axis, the commutation phase angle φ is calculated by calculating the remainder of the division from the position X obtained from the position detection value Pfx and the core pitch P of the X axis motor. By the mod function to
φ = mod (X, P)
Is calculated by

  82 is a primary sine wave generating means, which inputs a commutation phase angle φ and generates sin (φ). Reference numeral 83 denotes a secondary sine wave generating means that inputs a commutation phase angle φ and generates sin (2φ). It is possible to provide third-order, fourth-order... N-th order sine wave generating means as required.

  A constant holding means 84 holds a constant a1 added to the commutation phase angle φ for the primary sine wave calculation. 84 is also a constant holding means for holding a constant a2 to be added to the commutation phase angle φ for the secondary sine wave calculation. As the holding values of these constant holding means, appropriate values are set in advance by engineering.

  A constant holding means 86 holds a coefficient k1 for multiplying the output of the primary sine wave generating means 82. 87 is also a constant holding means for holding a coefficient k2 for multiplying the output of the secondary sine wave generating means 83. The values held by these constant holding means are set to appropriate values by engineering in advance.

  Reference numeral 88 denotes an adding means, which adds the output of the primary sine wave generating means 82 multiplied by the coefficients k1 and k2 and the output of the secondary sine wave generating means 83 to obtain a cogging correction signal Fex for suppressing ripples due to cogging. It is generated and added to the thrust command value Fdx of the speed control unit 5. The cogging correction signal Fex is a signal having the same amplitude and opposite phase as the disturbance thrust generated by cogging.

  The X-axis position control system and the ripple suppression means have been described above. However, the same position control system is constructed for the rotation suppression control around the Y-axis and the Z-axis (θ-axis), and the ripple for correcting the cogging thrust on each axis Suppression means is provided.

  In the conventional ripple suppression means, the constants a1 and a2 added to the commutation phase angle φ and the output of the primary sine wave generation means 82 and the output of the secondary sine wave generation means 83 are multiplied in the process of calculating the cogging correction signal. The constants k1 and k2 are fixed values set in advance by engineering.

However, since the cogging thrust varies depending on the speed and direction of the slider, it is difficult to obtain an optimal cogging correction signal by using a fixed constant based on the position, and the ripple is suppressed because correction is not sufficient. The effect is limited.
In addition, in the XY stage that moves on the grating platen, the cogging thrust generated when moving in the Y-axis direction has a component force not only in the Y-axis direction but also in the rotation direction around the X-axis and Z-axis (θ-axis). It exists, and ripple suppression cannot be performed by correction for each axis.

  Therefore, the problem to be solved by the present invention is to realize an XY stage that can perform cogging correction reflecting the speed of the slider and obtain a sufficient cogging correction result including interference with other axes.

In order to achieve such an object, the configuration of the present invention is as follows.
(1) Based on the commutation phase angle of the alternating current corresponding to the X-axis and Y-axis positions, the slider is moved and controlled in the X-axis direction or the Y-axis direction by the alternating current supplied to the X-axis motor and the Y-axis motor. In the XY stage for suppressing the ripple due to the cogging thrust generated in the slider by the cogging correction signal calculated as follows:
A constant setting unit configured to hold a constant corresponding to the speed of the slider, and to change at least one of the commutation phase angle and the cogging correction signal according to the speed of the slider ;
Constant correction means for changing a constant from the constant setting means based on difference information between a thrust command value to the slider and a thrust detection value of the slider;
An XY stage characterized by comprising:

(2) The XY stage according to (1) , further comprising constant generating parameter correcting means for correcting the content of the constant setting means based on the output of the constant correcting means.

(3) The slider is moved and controlled in the X-axis direction or the Y-axis direction by an AC current supplied to the X-axis motor and the Y-axis motor, and based on the commutation phase angle of the AC current corresponding to the X-axis and Y-axis positions. In the XY stage for suppressing the ripple due to the cogging thrust generated in the slider by the cogging correction signal calculated by
A cogging correction signal based on the commutation phase angle of the Y axis is added to the cogging correction signal of the X axis, and a cogging correction based on the commutation phase angle of the X axis is added to the Y axis cogging correction signal. Ripple suppression means to add signals ,
The ripple suppression means is
A constant setting unit configured to hold a constant corresponding to the speed of the slider, and to change at least one of the commutation phase angle and the cogging correction signal according to the speed of the slider;
Constant correction means for changing a constant from the constant setting means based on difference information between a thrust command value to the slider and a thrust detection value of the slider;
XY stage characterized by having.

(4) The cogging correction signal in the ripple suppression means of the θ-axis control system that suppresses rotation around the Z axis is generated from the commutation phase angle of the X axis and the commutation phase angle of the Y axis. The XY stage as described in (3) .

(5) The XY stage according to (3) , further comprising constant generating parameter correcting means for correcting the contents of the constant setting means based on the output of the constant correcting means.

(6) The XY stage according to any one of (1) to (5) , wherein the cogging correction signal is calculated from calculation of a sine wave function and cosine wave function with respect to the commutation phase angle.

As is apparent from the above description, the present invention has the following effects.
(1) Minimize ripples by correcting the influence of cogging thrust, which is a drawback of hybrid type surface motors, to the speed factor of the slider to minimize deviation from the position command value during slider movement. Can do.

(2) This makes it possible to provide an XY stage that can be applied to a precision scanning exposure apparatus, precision coating apparatus, and precision / high-speed laser processing machine that require precision during slider movement.

(3) The constant data self-correction / creation function can provide an XY stage that can easily reduce the number of manufacturing steps and perform readjustment on site.

  The present invention will be described in detail below with reference to the drawings. FIG. 1 is a functional block diagram showing an X-axis of an embodiment of an XY stage to which the present invention is applied. The same elements as those in the conventional XY stage described with reference to FIG. Hereinafter, the characteristic part of the present invention will be described.

  In FIG. 1, a dotted line block 100 is an X-axis ripple suppressing means to which the present invention is applied. The configuration of the commutation phase detection means 101, the primary sine wave generation means 102, the secondary sine wave generation means 103, and the addition means 104 is composed of the commutation phase detection means 81 and the primary sine in the conventional XY stage described with reference to FIG. The configuration of the wave generating means 82, the secondary sine wave generating means 83, and the adding means 88 is the same.

  Reference numeral 105 denotes constant setting means forming a characteristic part of the present invention, which inputs the speed detection value Vfx of the speed converter 3 and sets the constants a1, a2 and k1, k2 by calculating the optimum values corresponding to the speed Vfx. . The calculation may be a function calculation based on an appropriate algorithm, but a general configuration is such that constants are read from a table in which the speed detection values divided at an appropriate resolution are associated with optimum constants.

  Reference numeral 200 denotes an acceleration sensor attached to the slider 1, and reference numeral 300 denotes thrust conversion means, which calculates a thrust estimation value Fax including cogging thrust acting on the slider 1 based on a detection value of the acceleration sensor 200. The thrust estimation value Fax and the thrust command value Fdx of the speed controller 5 are subtracted to calculate difference information dx.

  106 is a constant correction means for the primary sine wave, which receives the difference information dx and the output of the primary sine wave generation means 102, compares the amplitude and phase of both, and corrects the constant a1 based on the amplitude error and the phase error. A signal kg1 for correcting the signal kp1 and the constant k1 is generated and added to a1 and k1, respectively.

  Similarly, reference numeral 107 denotes constant correction means for the secondary sine wave. The difference information dx and the output of the secondary sine wave generation means 103 are input, the amplitude and phase of both are compared, and a constant is determined based on the amplitude error and the phase error. A signal kp2 for correcting a2 and a signal kg2 for correcting the constant k2 are generated and added to a2 and k2, respectively.

  Reference numeral 108 denotes constant generation parameter correction means, which inputs correction signals kp1, kg1, and kp2, kg2 of the constant correction means 106 and 107, corrects constant generation parameters in the constant setting means, and generates constants a1, a2, and k1. , K2 is corrected.

  In this way, the estimated thrust Fax acting on the slider 1 is fed back, the amplitude error and phase error of the sine wave generating means is obtained for each order from the difference information dx with the thrust command value Fdx, and feedback control is performed to correct the constant set value. The cogging correction effect can be further enhanced.

  By correcting the constant generation parameters of the constant setting means 105 with reference to the difference between the correction signals kp1, kg1, and kp2, kg2 after the feedback control and the set constants a1, a2, k1, and k2, the accuracy of the learning effect can be improved. The high constant setting means 105 can be tuned.

  As described above, the embodiment in which the ripple suppression unit of the present invention is applied to the X axis has been described, but ripples due to cogging thrust of each axis are effectively suppressed by providing the same ripple suppression unit for the Y axis and the θ axis. can do.

  The embodiment described above is an improvement of the ripple suppressing means by the cogging thrust in each of the X axis, the Y axis, and the θ axis. However, in an XY stage using a surface motor, there is interference from other axes, and the cogging thrust acting on each axis also interferes with the other axes, so that each axis alone is not completely corrected.

  FIG. 2 is a functional block diagram showing another embodiment of the present invention in which a cogging correction signal for each axis is added to a cogging correction signal for another axis. A chain line area A is an X-axis control system, B is a Y-axis control system, and C is a θ-axis control system, and thrusts Fx, Fy and torque Tθ are applied to the slider 1 from each control system.

  The cogging thrust Frxx of the own axis and the cogging thrust Fryx due to the interference of the Y axis act on the X-axis thrust Fx. Similarly, the cogging thrust Fryy of the own axis and the cogging thrust Frxy due to the interference of the X axis act on the thrust Fy of the Y axis. Further, cogging thrusts Trxθ and Tryθ due to interference between the X-axis and the Y-axis act on the torque Tθ on the θ-axis.

  The position sensor 2 outputs an X-axis position detection value Pfx, a Y-axis position detection value Pfy, and a θ-axis position Pfθ of the slider 1 and gives them to each axis control system. Reference numerals 41, 42, and 43 denote position control units of the respective axis control systems, which calculate a deviation between the position command values Psx, Psy, and Psθ of each axis and the position detection values Pfx, Pfy, and Pfθ of each axis to calculate the speed command value Vsx. , Vsy, Vsθ are output.

  Deviations evx, evy, evθ of speed detection values Vfx, Vfy, Vfθ of the speed converters 31, 32, 33 of the respective axes and speed command values Vsx, Vsy, Vsθ of the respective axes are the speed control units 51, The thrust command values Fdx and Fdy for the X and Y axes and the torque command value Tdθ for the θ axis are output at 52 and 53.

  The thrust command values for these axes are added to the cogging correction signals from the ripple suppression means for each axis by the addition means 71, 72, 73 for each axis, and the torques for the X and Y thrust generators 61, 62 and the θ axis are added. It is input to the generator 63 and converted into thrusts Fx, Fy and torque Tθ and acts on the slider 1.

  A dotted block 400 is an X-axis ripple suppression unit, a self-axis commutation phase detection unit 401, a correction value generator 402 for the cogging thrust of the own axis, and a correction value generator for the cogging thrust due to interference from the Y-axis. 403, constant holding means 404 and 405 for these correction value generators.

  A dotted block 500 is a Y-axis ripple suppression unit, a self-axis commutation phase detection unit 501, a correction value generator 502 for the cogging thrust of the own axis, and a correction value generator for the cogging thrust due to interference from the X axis. 503, constant holding means 504 and 505 for these correction value generators.

  A dotted line block 600 is a θ-axis ripple suppression means, a correction value generator 601 for cogging thrust due to interference from the X axis, a correction value generator 602 for cogging thrust due to interference from the Y axis, and these correction value generators. Constant holding means 603, 604 for

  The commutation phase outputs φx of the X-axis commutation phase detection means 401 are output to the correction value generator 402 for the own axis and to the correction value generator 503 for the Y axis and the correction value generator 601 for the θ axis. Is also output. Similarly, each commutation phase output φy of the Y-axis commutation phase detection means 501 is output to the self-axis correction value generator 502, the X-axis correction value generator 403, and the θ-axis correction value generation. Also output to the device 602.

  The cogging correction values Fex and Fey of the X-axis correction value generators 402 and 403 are added and added to the thrust command value Fdx by the adding means 71. Similarly, the cogging correction values Fey and Fex of the Y-axis correction value generators 502 and 503 are added and added by the adding means 72 to the thrust command value Fdy. Similarly, the cogging correction values Teθx and Teθy of the θ-axis correction value generators 601 and 602 are added and added to the torque command value Tdθ by the adding means 73.

  In the embodiment of FIG. 2, the constant holding means in the ripple suppressing means for each axis is represented by a simple block for the sake of simplicity. However, the constant setting means reflecting the speed of the slider described in FIG. The constant correction means based on the difference information d and the constant generation parameter correction means can be applied.

  In the embodiment described above, the cogging correction signal is calculated by high-order sine wave function calculation based on the commutation phase angle φ. However, the cogging correction signal is calculated by calculating the sine wave function and the cosine wave function with respect to the commutation phase angle φ. It is also possible to calculate from this calculation.

It is a functional block diagram which shows one Embodiment of the XY stage to which this invention is applied. It is a functional block diagram which shows other embodiment of this invention. It is the functional block diagram which showed the structural example of the conventional XY stage position control system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Slider 2 Position sensor 3 Speed converter 4 Position control part 5 Speed control part 6 Thrust generation part 7 Addition means 100 Ripple suppression means 101 Commutation phase detection means 102 Primary sine wave generation means 103 Secondary sine wave generation means 104 Addition Means 105 Constant setting means 106, 107 Constant correcting means 108 Constant generating parameter correcting means

Claims (6)

The slider is moved and controlled in the X-axis direction or Y-axis direction by AC current supplied to the X-axis motor and Y-axis motor, and is calculated based on the commutation phase angle of the AC current corresponding to the X-axis and Y-axis positions. In an XY stage that suppresses ripple due to cogging thrust generated in the slider by a cogging correction signal
A constant setting unit configured to hold a constant corresponding to the speed of the slider, and to change at least one of the commutation phase angle and the cogging correction signal according to the speed of the slider ;
Constant correction means for changing a constant from the constant setting means based on difference information between a thrust command value to the slider and a thrust detection value of the slider;
An XY stage characterized by comprising: 2. The XY stage according to claim 1, further comprising constant generating parameter correcting means for correcting contents of the constant setting means based on an output of the constant correcting means. The slider is moved and controlled in the X-axis direction or Y-axis direction by AC current supplied to the X-axis motor and Y-axis motor, and is calculated based on the commutation phase angle of the AC current corresponding to the X-axis and Y-axis positions. In an XY stage that suppresses ripple due to cogging thrust generated in the slider by a cogging correction signal
A cogging correction signal based on the commutation phase angle of the Y axis is added to the cogging correction signal of the X axis, and a cogging correction based on the commutation phase angle of the X axis is added to the Y axis cogging correction signal. Ripple suppression means to add signals,
The ripple suppression means is
A constant setting unit configured to hold a constant corresponding to the speed of the slider, and to change at least one of the commutation phase angle and the cogging correction signal according to the speed of the slider;
Constant correction means for changing a constant from the constant setting means based on difference information between a thrust command value to the slider and a thrust detection value of the slider;
XY stage characterized by having. 4. The cogging correction signal in the ripple suppression means of the θ-axis control system that suppresses rotation about the Z axis is generated from the commutation phase angle of the X axis and the commutation phase angle of the Y axis. XY stage as described in. 4. The XY stage according to claim 3, further comprising constant generating parameter correcting means for correcting the contents of the constant setting means based on the output of the constant correcting means. 6. The XY stage according to claim 1, wherein the cogging correction signal is calculated from a sine wave function calculation and a cosine wave function calculation with respect to the commutation phase angle.

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