JP5873384B2 - Table positioning device - Google Patents

Description

  The present invention includes a table moving mechanism unit, a power applying unit, a moving displacement amount detecting unit, and a positioning control circuit unit, and is used for positioning a table with ultra-high speed (2.5 mm / sec) and high accuracy (1 nm). The present invention relates to a table positioning device.

  Although it is commonly used as a technical means for positioning an object with high accuracy in terms of upper concepts, specifically (subordinate concepts) include, for example, a semiconductor exposure apparatus (large and expensive) using a laser beam, for example, There are many technical incompatibility with the positioning device (compact and inexpensive) for optical fiber testing and research.

  In connection with the latter, the present applicants firstly introduced a moving displacement detector, that is, an optical device for achieving a significant reduction in size, weight, cost, and ease of handling in order to establish industrial use and expand its use. A displacement detection device (see Patent Document 1) was proposed. This apparatus is a three-grating method using three optical gratings, and can achieve high accuracy and high detection speed.

  Next, the optical displacement detection device is accommodated in the stage (between the base and the table) and used as a movement displacement amount detection unit for the table, and the table movement mechanism unit is used for the coarse movement microhead and the fine movement piezo. A manual positioning device (Patent Document 2) in which actuators are arranged in series has been proposed.

  In addition, an automatic positioning device (Patent Document 3) has been proposed in which a coarse drive is a motor-driven screw shaft, and a fine motion piezo actuator and a screw shaft are arranged in series in the moving direction of the table. Subsequently, an automatic positioning device (Patent Document 4) was proposed in which a responsive displacement allowing means or the like was provided to achieve higher accuracy. In addition, improvements were made for each component. For example, a moving displacement amount detection unit (Patent Document 5) including a circuit (multiplication circuit and division circuit) has been proposed. Thus, it was possible to position the table with high precision (for example, 0.1 μm) with an ultra-thin shape (small and light) as a whole.

  Furthermore, on top of these technical stacks, the entire area (tables) where the piezo actuators have been removed is used to eliminate the disadvantages (discontinuity, long-time drive) of the piezo-actuator drive type (continuous, short-time drive). A so-called full-range screw shaft drive type table positioning device (Patent Document 6) has been proposed in which the movement range is formed so as to be driven by a single screw shaft. According to this proposed apparatus, high-accuracy positioning can be performed in a relatively short time by continuous driving.

  However, although this proposed positioning device (Patent Document 6) can shorten the positioning time, the positioning accuracy is about 0.01 μm (10 nm), and the positioning accuracy is one step higher (for example, 0.001 μm (1 nm or less)). Accuracy cannot be guaranteed.

  Here, in order to further improve the positioning accuracy, the constituent elements (for example, screw shaft lead, motor step angle, speed reducer presence / absence, scale pitch, number of movement displacement detection signal divisions, etc.) should be as small as possible. It is necessary to do more. However, even if individual components are reduced or increased in number independently, there is no meaning as long as the combination thereof does not have mechanical, optical, electrical, and electronic consistency. In other words, it lacks practicality for an increased economic burden including manufacturing costs.

  In view of this, a high-accuracy positioning device has been proposed (Patent Document 7) in which the drive system, the detection system, and the control system are formed from a combination of specific constituent elements that can establish positioning accuracy of 1 nm or less. According to this proposal, an unstable factor can be detected and resolved automatically, and high-precision positioning of 1 nm or less can be ensured as shown in FIG. 12, and a small and inexpensive positioning device can be provided.

JP-A-7-286816 JP-A-8-185238 JP-A-9-192958 JP-A-10-58267 JP 2000-235417 A JP 2004-101320 A JP 2007-219832 A

  Certainly, the spread of high-precision (1 nm) positioning devices began at the same time as the patent of the proposed device (Patent Document 7) was established. That is, it is considered that this is a proof that high-precision positioning can be performed while ensuring stable operation in practice.

  The diversification of specific modes of use accompanying this widespread expansion is unknown. For example, measurement and positioning of an electronic thin wire that requires continuity, positioning for alignment of an optical fiber that requires expansion of a positioning range, positioning of a probe (downward load) with respect to a near field with a large pulling drive load, and the like.

  By the way, in any usage mode, there is a strong demand for further expansion of the high-precision positioning possible region, that is, the stroke (table movement range). On the other hand, on the premise that the target position can be positioned with high accuracy (1 nm), there is a strong demand for further shortening of the table moving time. Referring to FIG. 12, it is pointed out that if the high-speed moving time (about 1.998 Sec) can be shortened to 1/2 or 1/3, the work efficiency is greatly improved. However, if it is assumed that the positionable region is enlarged, there is a trade-off relationship between higher accuracy and higher movement speed.

  Moreover, the proposed positioning device (Patent Document 7) carefully examines and experimentes on the optimization of each component, and is consistent with many components such as genetic recombination and their rank-specific values. It is the ultimate one built with choices and combinations of them. Moreover, it was established by spending a lot of verification work and enormous time and labor. Therefore, no more drastic solution can be found by just optimizing the components.

  Here, there is a strong demand for research and development that involves a change in concept, that is, the development of a new positioning device that can perform high-precision positioning at ultra-high speed.

  An object of the present invention is to provide a full-range screw shaft drive type table positioning apparatus capable of stably performing high-precision positioning of 1 nm or less at an ultra-high speed and stably.

  When analyzing requests / indications from users in practice, further speedup is to shorten the time required from the start of positioning to completion of positioning at the target position. On the other hand, from the producer's point of view, it is natural to examine and introduce components that advance, but the performance of all components does not advance synchronously. For example, even if the detection system can be speeded up, the drive system and the control system may not be achieved. In order to increase the movement speed, the frequency of the drive pulse signal (motor rotation control signal) must be further increased. However, the maximum response frequency of each electronic / electrical component is not the same. In particular, the maximum response frequency of the motor driver is the lower one.

  It is difficult to reduce the time for medium speed rotation (movement) control and low speed rotation (movement) control essential for high-accuracy (1 nm) positioning because of, for example, the relationship with cumulative representative read error. Moreover, since the time for medium / low speed movement control is shorter than the time for high speed movement control, the overall effect of shortening is low. In other words, the significance of working on shortening of medium / low speed movement control is diminished. Thus, it is desirable to reduce the time for high-speed movement control. However, since the resolution of the drive pulse signal and the maximum response frequency of the motor driver are limited, it is extremely difficult to reduce the time for high-speed rotation (movement) control.

  Here, in view of the demands and indications of actual users, the resolution of the drive pulse signal related to the high-speed rotation control may be reduced as long as the final high-precision positioning accuracy can be ensured. If the motor driver is operated at a frequency lower than the maximum response frequency, there should be no problem. Therefore, if these items are used skillfully, both high precision and ultra high speed should be achieved.

  By the way, the magnitude of the designated movement amount is an exclusive matter of the user and is arbitrary. Therefore, if only limited to the ultra-high speed rotation control, for example, a trouble may occur when the designated movement amount is small. For example, when the value of the designated movement amount is equal to or less than the resolution of the drive pulse signal for ultra-high speed rotation control, there is a possibility that positioning control cannot be performed.

  Thus, according to the present invention, the number of motor driver divisions can be switched between the number of divisions for high-speed rotation control and the number of divisions for ultra-high-speed rotation control, and ultra-high-speed rotation control and high-speed rotation control are selectively performed under predetermined conditions. It is configured to be able to shift to medium / low speed rotation control after that.

  Specifically, the table positioning device according to the first aspect of the invention is a table moving mechanism that uses a screw shaft whose lead is 1 mm or less and can move the table relative to the base, and a stepping connected to the screw shaft. A power applying unit that includes a motor and a motor driver and rotationally drives the screw shaft based on the motor rotation control signal to apply moving power to the table moving mechanism unit that can move the table by 1 nm at a minimum; and three optical gratings; A moving displacement amount detection unit that includes a signal dividing circuit and that generates and outputs a moving displacement amount detection signal of 1 nm per pulse with a bright line and a dark line of each optical grating of 2 μm, and an open position. Motor rotation control signals for high speed rotation by loop control, medium speed rotation by closed loop control, and low speed rotation in this order. A positioning control circuit unit that generates and outputs a positioning control signal for positioning the table at the target position to the power applying unit, and a mechanical vibration generated in the device components during low-speed rotation. In a table positioning device equipped with an apparent signal ignoring means that ignores the apparent motor rotation control signal, a stepping motor is directly connected to the screw shaft, and the motor driver is selectively set to the high-speed rotation division number and the ultra-high-speed rotation division number. The memory is configured to be switchable and stores division number selection switching information for selecting either the high-speed rotation division number or the super-high-speed rotation division number, and the specified positioning information and memory specified in the actual positioning operation. Number of divisions for selecting the optimum number of motor driver divisions for the actual positioning operation using the stored division number selection switching information There is provided selection means and switching signal generation output means for generating and outputting a division number selection switching signal for switching to the selected optimum division number to the motor driver, and the positioning control circuit unit rotates the motor for high-speed rotation by open loop control. It is formed so that it can output a motor rotation control signal for ultra-high speed rotation instead of a control signal, and it is formed so that it can execute ultra-high-speed positioning control much faster than high-speed positioning control by open loop control. To do.

  In the invention of claim 2, the screw shaft is a ball screw shaft having a lead of 1 mm, and the signal division number of the signal division circuit is selected to be 2,000.

  In the invention of claim 3, the step angle of the stepping motor is selected to be 0.36 degrees.

  In the invention of claim 4, the number of divisions for high-speed rotation is 1,000, and the number of divisions for ultra-high-speed rotation is 20.

  Further, the invention according to claim 5 is information associating the reference moving speed and the reference moving amount until the division number selection switching information reaches the maximum response frequency of the motor driver.

  Further, the invention according to claim 6 is the case where the division number selection means is such that the designated movement speed is equal to any of the reference movement speeds and the designated movement amount is shorter than the reference movement quantity corresponding to the reference movement speed. The number of divisions for high-speed rotation can be selected as the optimum number of divisions, and when the specified movement amount is longer than the reference movement amount corresponding to the reference movement speed, the division number for ultra-high-speed rotation can be selected as the optimum division number Is formed.

  Furthermore, in the seventh aspect of the invention, when the positioning control circuit unit executes the ultra-high-speed positioning based on the designated movement amount, the positioning completion position is assumed to be a position before reaching the accumulated representative read error equivalent position. Is formed so that the number of pulses obtained by adding one pulse to the number of pulses corresponding to the positioning control signal corresponding to the designated movement amount can be generated and output to the power applying unit.

  In the invention of claim 8, a mechanical damper is connected to the rotating shaft of the stepping motor.

  According to the first aspect of the present invention, a high-precision positioning of 1 nm or less can be performed stably at an ultra-high speed, and a small and lightweight table positioning apparatus can be provided.

  Further, according to the invention of claim 2, compared with the case of the invention of claim 1, further cost reduction and operation stabilization can be achieved.

  According to the invention of claim 3, it is effective in reducing the number of divisions of the motor driver.

  According to the invention of claim 4, it is possible to perform an operation in which high speed and ultra high speed are switched without imposing an excessive burden on the motor driver.

  Furthermore, according to the invention of claim 5, high-speed movement and ultra-high speed movement can be stably switched while ensuring the frequency operation below the maximum response frequency of the motor driver, and the adaptability to the driving mode is wide.

  Furthermore, according to the sixth aspect of the invention, a positioning operation in which the moving speed and the moving amount are designated can be performed, and stable positioning can be performed regardless of the designated values.

  Furthermore, according to the seventh aspect of the present invention, it is possible to quickly take over from the ultra high speed movement operation to the medium speed movement operation, and it is effective in shortening the time until the final positioning is completed.

  According to invention of Claim 8, the mechanical vibration at the time of low-speed movement driving | operation can be absorbed, and the more stable positioning can be performed.

It is a top view for demonstrating the stage which concerns on embodiment of this invention. Similarly, it is a side view for explaining a stage. Similarly, it is a top view for demonstrating the stage of the state which removed the table. Similarly, it is side sectional drawing based on arrow sight line AA of FIG. Similarly, it is a cross-sectional view based on arrow BB of FIG. Similarly, it is a block diagram for explaining a positioning drive control unit. Similarly, it is a figure for demonstrating a memory and division number selection switching information. Similarly, it is a flowchart for explaining a positioning drive control operation (1). Similarly, it is a flow chart for explaining positioning drive control operation (2). Similarly, it is a timing chart for explaining a positioning drive control operation. Similarly, in the timing chart for explaining the positioning drive control operation example, (A) shows a case of 0.5 mm / sec, (B) shows 1.0 mm / sec, and (C) shows a case of 2.5 mm / sec. It is a timing chart for demonstrating the positioning drive control operation example of a prior art example.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  As shown in FIGS. 1 to 11, the table positioning apparatus includes a stage 10, a table moving mechanism unit 40, a power applying unit 50, a movement displacement amount detecting unit 60, a positioning control circuit unit 90, and an apparent signal ignoring unit 100. In the basic configuration, the stepping motor 51 is directly connected to the screw shaft 41, and the motor driver 93 is formed so as to be selectively switchable between the high-speed rotation division number (1,000) and the super-high-speed rotation division number (20). , A memory 82M, division number selection means (81, 82) and switching signal generation output means (88) are provided, and the positioning control circuit 90 can output a motor rotation control signal Pdhh for ultra-high speed rotation by open loop control. In comparison with high-speed positioning control by open loop control, ultra-high-speed positioning control that is much faster than that is possible.

  To be sure, the basic configuration of the table positioning device is that the table moving mechanism section 40 is a whole-area screw shaft rotation drive type, the power applying section 50 is a motor rotation drive type, and the motor output from the positioning control circuit section 90 is used. The table 31 can be moved by 1 nm at a minimum based on the rotation control signal Pd, and the moving displacement detection unit 60 includes three optical gratings (61F, 63S, 63T), and a moving displacement detection signal Psd of 1 nm per pulse. It is possible to generate and output, and the positioning control circuit 90 can switch and output motor rotation control signals (Pdh, Pdm, Pdl) for high speed rotation by open loop control, medium speed rotation by closed loop control, and low speed rotation in this order. Further, the apparent signal ignoring means 100 is provided to cause mechanical vibration of the stage 10 that occurs during low-speed rotation. The apparent signal are neglected movable around a PDZ (motor rotation control signal apparent) that.

  1 to 5, a stage 10 includes a base 11 and a table 31, and the table 31 is mounted so as to be slidable (movable) in the base axis (Z) direction via left and right cross roller guides 21. . The base 11 and the table 31 are made of an aluminum alloy and are reduced in weight. The table 31 is a flat plate (120 mm × 120 mm) thin plate shape, and the average plate thickness is 12 mm. The mass of the table 31 is 0.5 kg when there is no load (the mass of the table alone), and 10 kg when the maximum load (a mass including a load such as a workpiece). In addition, in this embodiment, the table 31 and the base 11 are symmetrically formed in the width direction about the base axis (Z), thereby facilitating the processing and cost reduction.

  The table 31 can reciprocate between the rightward rearward limit position (31R) and the leftward forward limit position (31L) indicated by a two-dot chain line in FIG. 2 (entire range: movable range of the table: 50 mm). . The forward limit position (31L) and the reverse limit position (31R) are detected by limit sensors 29 (29R, 29L) shown in FIG. The limit position detection signal lt (ltr, ltl) is sent to the positioning control circuit 90 as shown in FIG. 6 and used as an emergency stop signal.

  As shown in FIG. 4, the table moving mechanism section 40 includes a screw shaft 41 attached to the base 11 side and a nut member 45 attached to the table 31 side and screwed to the screw shaft 41, and includes a motor (stepping motor). 51), the screw shaft 41 is rotationally driven using the moving power applied from 51), so that the table 31 can be moved in the Z direction relative to the base 11 (reciprocal relative movement). In this embodiment, the screw shaft 41 is a sophisticated ball screw shaft with little backlash and the like, and the nut member 45 has a structure corresponding thereto.

  The right end side of the ball screw shaft (41) is rotatably supported on the base 11 via a bearing 23, and is connected to an output shaft 51S of a motor 51 via a honeycomb type coupling 24 of FIG. The speed reducer, which is considered to be the cause of the intervening mechanical error, was wiped out.

  In this embodiment, the screw lead of the ball screw shaft (41) is set to 1 mm from the viewpoints of easy handling in signal division and control, and the current advantage of the apparatus economy. In addition, you may construct | assemble as a 1 mm or less screw lead (for example, 0.5 mm).

  A mechanical damper 28 is connected to the stepping motor 51 so that vibration during low-speed rotation operation can be mechanically suppressed or absorbed. As this damper 28, a clean damper (manufactured by Oriental Motor) was used as one in which the donut-shaped internal inertial body and the silicon gel absorb vibration and exhibit a stable damping effect. The stepping motor 51 can also be manually rotated with a knob (an outer frame of the damper 28).

  The power application unit 50 is a motor rotation drive type including a motor (stepping motor 51) and a motor driver 93, and is a rotation drive pulse signal Pd (high-speed rotation drive pulse signal) that is a motor rotation control signal output from the positioning control circuit unit 90. Based on Pdh, medium speed rotation drive pulse signal Pdm, and low speed rotation drive pulse signal Pdl), the screw shaft 41 is rotationally driven to move the table 31 in the Z direction by 1 nm at a minimum.

  Furthermore, the power applying unit 50 is formed so as to be able to move the table 31 in the Z direction by a minimum of 50 nm by rotationally driving the screw shaft 41 based on the new ultra-high speed rotation drive pulse signal Pdhh as the rotation drive pulse signal Pd. . Since the resolution of the ultra-high speed rotation drive pulse signal Pdhh is 50 nm, if the number of drive pulse signals is the same, the speed can be significantly increased compared to the moving speed (0.5 mm / sec) of the high-speed rotation drive pulse signal Pdh with a resolution of 1 nm. realizable. That is, it can move at an ultra-high speed (2.5 mm / sec).

  The motor driver 93 shown in FIG. 6 is a micro-step drive type, and has a function of subdividing the motor rotation angle per pulse according to the number of drive divisions (in this embodiment, “1,000” and “20”). have. Since the step angle of the motor 51 in this embodiment is 0.36 (360 / 1,000) degrees, when the division number is 1,000, the motor rotation per pulse (1 pulse: motor rotation control signal) The angle is 0.00036 degrees [= 0.36 degrees × (1 / 1,000)]. The number of drive divisions is about “1,000” in terms of the electronic maximum response frequency of the motor driver 93 and the addition of a margin for ensuring stable operation. Further improvement is desired in the future.

  Referring to FIG. 10, in the case of the number of divisions for high speed (1,000), the power application unit 50 determines the ball based on the motor rotation control signal (rotation drive pulse signal Pd) output from the positioning control circuit unit 90. The screw shaft (41) is driven to rotate, and the table 31 is minimum 1 nm in the Z direction [= lead (1 mm / 360 °) × step angle (360 ° / 1,000) × driver division number (1 / 1,000) ] Can be moved one by one.

  When the number of divisions for ultra-high speed (20) is used, the table 31 is set to a minimum of 50 nm in the Z direction [= lead (1 mm / 360 °) × step angle (360 ° / 1,000) × driver division number (1 / 20)] can be moved one by one. That is, as a measure for shortening the time required from the start of positioning to the completion of positioning at the target position, ultra-high-speed rotation with a resolution (50 nm) lower than the resolution (1 nm) of the high-speed rotation drive pulse signal Pdh used for open loop control A drive pulse signal Pdhh is generated. As a result, it is possible to perform ultra-high speed rotation driving in a region that does not exceed the maximum response frequency of the motor driver 93.

  The movement displacement amount detection unit 60 includes three optical gratings (61F, 63S, and 63T) and a signal division circuit 95, and is formed so as to be able to generate and output a movement displacement amount detection signal Psd with high resolution (1 nm / 1 pulse). Yes. Note that the resolution of the moving displacement detection signal Psd is maintained at 1 nm / 1 pulse even during the ultra-high-speed rotation driving operation with the resolution (50 nm) with the super-high-speed division number (20). Therefore, there is no possibility of shifting to the medium speed rotation drive at any time during the ultra high speed rotation drive operation and causing an impediment to accuracy in the medium speed rotation drive.

  Specifically, the movement displacement amount detection unit 60 is attached to the main scale 61 (61F) attached to the table 31 (base 11 side) and the base 11 (table 31 side) shown in FIG. The table for the base 11 is composed of an attached index scale 63 (63S, 63T), a detector (including a light emitter, a light receiver, an amplifier, an operational amplifier, etc.) 65 shown in FIG. The moving displacement amount 31 can be detected, and the detected moving displacement amount Psd can be fed back to the positioning control circuit 90 and output to the CPU 81.

  A screw shaft accommodating space 35 shown in FIG. 4 is provided on the table 31 side, and the nut member 45 and the main scale 61 are attached. Also, the substrate 68 (with the index scale 63 and the detector 65 attached) is provided in a planar posture from the outside in the detector housing space 69 shown in FIGS. It is installed so that it can be changed. That is, the moire adjustment performed while changing the planar posture of the index scale 63 and the inspection adjustment of the movement displacement detection unit 60 (detector 65 etc.) can be executed from the lower surface side of the base 11. Therefore, it is small, lightweight, low cost and easy to handle, and it is easy to expand the detectable effective length and to perform automatic positioning.

  The main scale 61 is provided with a first optical grating 61F shown in FIG. The scale 61 has a flat plate shape made of glass as a whole, and the shape in the width direction is bilaterally symmetric. By taking the right and left balance of the processing distortion, even higher precision can be detected. The table 31 is attached with the optical grating surface facing downward.

  A second optical grating 63S and a third optical grating 63T shown in FIG. 3 are arranged close to the index scale 63, thereby facilitating the shortening of dimensions and the establishment of parallelism with the first optical grating 61F. The index scale 63 also has a flat plate shape made of glass as a whole and is attached to the substrate 68 in an upward state.

  The substrate 68 is attached with the light receiving portion 66J shown in FIG. 5 located below the third optical grating 63T and the light emitting portion 66H located on the near side and below the second optical grating 63S. ing.

  The light emitting unit 66H includes an LED and a condenser lens (not shown), and is attached to the substrate 68 with a predetermined inclination angle. Effective utilization of diffused light can be increased. The gap between the scales 61 and 63 (the vertical distance in FIG. 4) can be increased. The light receiving unit 66J includes a light receiving element obtained by dividing one chip of the light receiving element into four corresponding to the four third optical gratings 63T shown in FIG. Therefore, variations in temperature characteristics and the like can be minimized, and the arrangement on the same plane can be automatically guaranteed.

  In the moving displacement detection unit 60, the diffused light from the light emitting element (LED) is collected by the lens, passes through the second optical grating 63S on the index scale 63, and passes through the first optical grating 61F on the main scale 61. Incident light efficiently. At this time, since light insulating means (not shown) is provided, diffused light is not directly incident on each light receiving element.

  The detection light reflected from the first optical grating 61F on the main scale 61 side is collected at one place on the index scale 63 and passes through the four third optical gratings 63T disposed close to the second optical grating 63S. Then, it enters each light receiving element (66J).

  Thus, if the index scale 63 and the main scale 61 are relatively displaced, the detector 65 outputs the scale signals φA and φB shown in FIG. 10 while analyzing the photoelectric conversion signals (output signals) from the respective light receiving elements. be able to.

  Since the second optical grating 63S and each third optical grating 63T are arranged close to each other in the longitudinal (Z) direction of the index scale 63, the plane including the second optical grating 63S and each third optical grating 63T and the first The parallelism with the plane including the optical grating 61F can be adjusted relatively easily. Handling is easy, and the size and cost of the apparatus can be reduced.

  The bright lines (widths) and dark lines (widths) of the first optical grating 61F of the main scale 61 and the second optical grating 63S and the third optical grating 63T of the index scale 63 are 2 μm, respectively. That is, the bright and dark scale pitches of the first optical grating 61F, the second optical grating 63S, and the third optical grating 63T are set to 4 μm, which can be transferred and copied after electron beam drawing and has a large cost reduction effect.

  6 and 10, each period of the scale signals φA and φB output from the detector 65 is 2 μm, the center voltage Vr is 2.5V, and the amplitude voltage Vpp is 2V. The signal dividing circuit 95 generates and outputs a divided detection pulse signal (movement displacement amount detection signal) Psd obtained by dividing the scale signal (φA-phase and φB-phase detection signals having a phase difference of 90 degrees with a sine wave) into 2,000. To do. That is, the minimum detection resolution of the movement displacement amount detection unit 60 can be set to 1 nm.

  Here, the positioning control circuit unit 90 includes a deviation counter, a signal switching element, and the like (not shown), a motor rotation control signal (Pdh) for high speed rotation by open loop control, and a motor rotation control for medium speed rotation by closed loop control. The signal (Pdm) and the motor rotation control signal (Pdl) for low speed rotation are switched in this order so that they can be output to the motor driver 93.

  Since the present invention intends to further increase the speed, it is based on open-loop high-speed rotation control with the motor rotation control signal (Pdh) as an input, and open-loop ultra-high speed with the motor rotation control signal (Pdhh) as an input. The rotation control is prioritized so that it can be selected and executed.

  In the closed loop control, a deviation counter or the like is operated, the command value (command pulse signal Psz) input from the operation control unit 80 (pulse signal control unit 85) is used as a target position signal, and the movement displacement amount detection unit 60 (signal division circuit) 95) and generating and outputting a drive pulse signal (Pdm or Pdl) using the movement displacement amount detection signal (post-division pulse signal Psd) input from 95) as a feedback signal.

  The open loop control is executed by generating and outputting the command value (command pulse signal Psz) input from the operation control unit 80 (pulse signal control unit 85) as it is as a drive pulse signal (Pdhh, Pdh) in a passing state. .

  The high-speed rotation speed of the stepping motor 51 based on the high-speed rotation drive pulse signal (motor rotation control signal) Pdh is set to the same value as the allowable maximum speed [f = 500 kHz] of the stepping motor. That is, the maximum rotation speed (fh = 500 kHz... 0.500 mm / sec) is selected. The motor rotation control signal for high speed rotation is output as a drive pulse signal Pdh having a high speed rotation frequency fh (500 kHz).

  The ultra high speed rotation speed of the stepping motor 51 based on the ultra high speed rotation drive pulse signal (motor rotation control signal) Pdhh is lower than the allowable maximum speed [f = 500 kHz] of the stepping motor 51 by reducing the resolution (50 kHz). ). That is, the maximum rotation speed (fhh = 50 kHz... 2.500 mm / sec) is selected. The motor rotation control signal for ultra-high speed rotation is output as a drive pulse signal Pdhh having an ultra-high speed rotation frequency fhh (50 kHz). In other words, the frequency is lowered (1/10) to reduce the load on the motor driver 93, and the movement amount per pulse is increased by 50 times to substantially increase the actual table movement speed.

  That is, in order to shorten the table moving time, the process before reaching the position corresponding to the cumulative representative lead error E [= (cumulative representative lead) − (cumulative reference lead) = 800 nm] of the ball screw shaft (structure) 41. The (distance) is moved at an allowable maximum speed. The “cumulative representative lead” is a straight line representing the inclination of the cumulative actual lead, and is a minimum of two from the curve indicating the cumulative actual lead with respect to the effective movement amount (or effective length of the threaded portion) of the ball screw (41). It is obtained by multiplication (or similar approximation method). The “cumulative actual lead” is an average tendency obtained from a cumulative lead diagram obtained by continuous measurement. The “cumulative reference lead” is the cumulative lead when rotated at an arbitrary number of revolutions according to the reference lead.

  Further, the low-speed rotation speed of the motor 51 based on the low-speed rotation drive pulse signal (motor rotation control signal) Pdl is selected to be the minimum speed (0.0002 mm / sec) that can prevent the occurrence of overrun. ing. The low-speed rotation motor rotation control signal is output as a drive pulse signal Pdl having a low-speed rotation frequency fl (200 Hz).

  The intermediate speed rotation speed of the motor 51 based on the medium speed rotation drive pulse signal (motor rotation control signal) Pdm is set to an intermediate value between them. That is, it is selected for the purpose of quickly performing a table moving operation for eliminating the deviation allowable value Eh (= Max. 800 nm) for high speed control and shortening the time. The medium speed rotation frequency fm is preferably selected to be a value (2 kHz) that is at least 10 times the value of the low speed rotation frequency f1 (200 Hz). Note that the medium-speed rotation driving process can be performed in a plurality (for example, two stages).

  Further, the medium speed rotation drive range is set to a medium distance range (Max. 63 nm) corresponding to 7.9% of the error E [equivalent distance (800 nm)] on the characteristics of the table moving mechanism unit (ball screw shaft structure or the like) 40. The low-speed rotation drive range is selected to be a small distance range (± 1 nm) corresponding to ± 100% of the distance (1 nm) corresponding to the minimum detection resolution (1 nm) of the movement displacement amount detection unit 60.

  Thus, as shown in FIG. 10, the final positioning is performed in a short time (0.68 seconds), which is the sum of the medium speed rotation drive time (about 0.37 seconds) and the low speed rotation drive time (about 0.31 seconds). Can do. Incidentally, when the error E (Max. 800 nm) is eliminated only by the low-speed rotation drive without performing the medium-speed rotation drive, it takes 10 times (= 4.00 seconds = 800 nm / 200 Hz).

  In FIG. 6, the positioning drive control unit 70 includes an operation control unit 80 (CPU 81, ROM 82 and RAM 83), a pulse signal control unit 85, a positioning control circuit unit 90, and a motor driver 93 that constitutes a part of the power application unit 50. A signal dividing circuit 95 constituting a part of the movement displacement amount detection unit 60 is incorporated. The vibration frequency detection means 101 is integrally formed in the positioning control circuit unit 90 including a deviation counter and the like, but is displayed outside the positioning control circuit unit 90 for convenience of explanation.

  The CPU 81 receives information input and set using the setting unit (PNL) 71 based on the setting storage control program stored in the ROM 82 and processes the data, and the received storage target information is stored in the work area of the RAM 83. Remember. The setting unit (PNL) 71 may have a touch panel structure integrated with a display unit (IND) 72 described later.

  A plurality of setting values may be set in advance for each storage target information, and one of them may be selected and stored in the work area using, for example, a dip switch. As the storage target information, a fixed value (for example, a low-speed rotation deviation allowable value) stored in the ROM 82 may be read and stored in the work area of the RAM 83 as it is.

  As the storage target information, the positioning command value (target position) shown in ST11 of FIG. 8 set / selected / commanded using the setting unit (PNL) 71, the moving speed command value of ST12, and the super high / high Medium / low speed rotation frequency fhh (50 kHz), fh (500 kHz), fm (2 kHz), fl (200 Hz), super high / high / medium / low speed rotation target position, and displacement (target position, for example) 5 mm), a reference frequency fs (25 Hz), a detection start position (5 mm-10 nm) that is a vibration frequency detection timing, and the like. The target position for ultra high / high rotational speed control may be set and stored at a value within the ultra high / high speed deviation allowable value Eh (Max. 800 nm). The target positions for medium / low speed rotation speed control may be set and stored at values within the medium / low speed deviation allowable value Em (Max. 63 nm).

  In the conventional example, the moving speed by the high-speed rotation control is set to a constant value (0.5 mm / sec) as in the case of the medium speed and the low speed. However, in this embodiment, the operator moves at an extremely high speed as with the positioning command value. An arbitrary value can be selected and set and input within a certain range (0.5 to 2.5 mm / sec) including the speed. From this point, the practicality is much higher.

  In the following, a description will be given of a case where the ultra high speed rotation target position and the high speed rotation target position by open loop control are set and stored as 800 nm, and the closed loop control target position is [(63-α)] nm. α is, for example, 6 nm. The low speed target position related to the closed loop control, that is, the final target position is set as ± 1 nm which is equal to the low speed rotation deviation allowable value El.

  It should be noted that the maximum rotation frequency fmax. Determined by the fixed value, that is, the characteristics of the motor driver 93 and the stepping motor 51 is determined. (= 500 kHz = fh), deviation allowable value Eh (Max. 800 nm), and the like are stored (stored) in the ROM 62 in advance.

  Further, the CPU 81 transmits various display target information to the display unit (IND) 72 based on the display control program stored in the ROM 82 and displays the information. The display target information includes a target position (set movement displacement amount), a current position (actual movement displacement amount and current deviation of the table), and the like. Various setting values can be selectively displayed.

  Next, the pulse signal control unit 85 includes an oscillator and the like, and in accordance with a command from the operation control unit 80 (CPU 81), the pulse signal Psz having a frequency (fhh, fh, fm, or fl) corresponding to the command is determined by the positioning control circuit unit 90. It can be generated and output.

  The division number selection means (81, 82) is formed of a ROM 82 that stores a division number selection program and a CPU 81 that executes the control program, and designated positioning information (target value) designated in actual positioning operation and FIG. The division number selection switching information stored in the memory 82M is used to select the optimum division number of the motor driver 93 for the actual positioning operation. The designated positioning information (target value) is set and input using a setting unit (PNL) 71. The designated movement speed is also input in the same manner.

  The memory 82M stores a guideline for selecting either the high-speed rotation division number (1,000) or the super-high-speed rotation division number (20), that is, division number selection switching information. The division number selection switching information (reference movement speed, reference limit movement amount) shown in FIG. 7 includes the reference movement speed Vs and the reference limit movement amount Xs that reach the maximum response frequency (1 Mbps) of the motor driver 93 according to this embodiment. It is the information which shows the relationship.

  That is, the movement amount when the frequency of the motor rotation control signal Pd reaches the maximum response frequency (1 Mbps) is set as the reference limit movement amount Xs, and the reference limit movement amount Xs is stored in association with the reference movement speed Vs. It is.

  That is, if the rising / falling characteristics of the moving speed are determined from the relationship between the stage 10 (11, 31) and the inertia of the stepping motor 51, the designated moving amount X is set when the reference moving speed Vs is set and started. Is equal to or greater than the reference limit movement amount Xs corresponding to the reference movement speed Vs (= designated movement speed V), the maximum response frequency (1 Mbps) is reached. If it is less than the reference limit movement amount Xs, the maximum response frequency (1 Mbps) is not reached.

  Referring to FIG. 7, for example, consider a case where the reference movement speed Vs3 is 1.8 mm / sec and the reference limit movement amount Xs3 is 0.025 mm. If the designated movement speed V3 is 1.8 mm / sec and the designated movement amount X3 is a value exceeding 0.025 mm (for example, 0.03 mm), the frequency of the motor driver 93 reaches the maximum response frequency (1 Mbps). Therefore, high-speed operation (500 kHz) with 1,000 divisions is impossible. That is, an ultra high speed operation (50 kHz) with a division number smaller than 1,000 (20 in this embodiment) is desirable. That is, by introducing a unique technical matter that lowers the resolution in the high-speed rotation region, ultra-high speed operation (1.8 mm / sec) exceeding the maximum speed (0.5 mm / sec) of the conventional example can be performed.

  However, even if the designated movement speed V3 is the same 1.8 mm / sec, the maximum response frequency (1 Mbps) will not be reached if the designated movement amount X3 is less than 0.025 mm (for example, 0.020 mm). High-speed operation (500 kHz) with a division number of 1,000 may be executed. In other words, there is always room for high-speed operation when the designated movement amount is small, instead of always performing ultra-high-speed operation. It is the expansion of adaptability to the actual operation.

  More specifically, for example, when the designated movement speed V1 is 0.8 mm / sec and the designated movement amount X1 is a value exceeding 0.05 mm (for example, 0.07), the maximum response frequency (1 Mbps) is reached. To high-speed rotation operation at a designated moving speed V1 (0.8 mm / sec) at a high-speed frequency (500 kHz) is prohibited. That is, the super high speed rotation operation is performed at the designated moving speed Vs1 (0.8 mm / sec) with the super high speed frequency (50 kHz).

  However, if the designated movement speed V1 is 0.8 mm / sec and the designated movement amount X1 is less than 0.05 mm (for example, 0.04 mm), the maximum response frequency (1 Mbps) will not be reached. High-speed rotation operation at the designated movement speed V1 (0.8 mm / sec) can be performed with the number of divisions (1,000). However, when the designated moving speed V1 is 0.5 mm / sec, high-speed rotation operation of the designated moving speed V1 (0.5 mm / sec) may be performed, and the highest speed (1. There is no need to switch to ultra high speed rotation at 0 mm / sec). Respect the operator's specification (0.8 mm / sec).

  Similarly, if the designated moving speed V4 is 2.5 mm / sec and the designated moving amount X4 is a value exceeding 0.02 mm (for example, 1.0005 mm), the designated moving speed V4 (50 kHz) at the super high speed frequency (50 kHz) is used. 2.5 mm / sec), ultra-high speed rotation operation is performed. Thus, the longer the designated movement amount, the greater the time reduction effect.

  If the designated movement amount X4 is small (for example, 0.0005) even at the same designated movement speed V4 (2.5 mm / sec), the designated movement speed V4 (2.5 mm / sec) based on the high-speed frequency (500 kHz). sec). Since the maximum response frequency (1 Mbps) is not reached, the number of divisions is not switched.

  Here, the division number selection means (81, 82) designates the division number selection switching information (reference movement speed Vs, reference switching movement amount Xs) stored in the memory 82M shown in FIGS. 6 and 7 and the actual positioning operation. The designated positioning information (designated movement speed V, designated movement amount X) is compared and determined, and the optimal number of divisions of the motor driver 93 for the actual positioning operation is selected.

  In other words, the division number selecting means (81, 82) sets the designated movement amount X to the reference limit movement amount Xs corresponding to the reference movement speed Vs when the designated movement speed V is equal to any of the reference movement speeds Vs. If it is longer, the super-high-speed rotation division number (20) is selected as the optimum division number [YES in ST13 in FIG. 8 (denoted as Y), ST14]. On the contrary, when the designated movement amount X is shorter than the reference limit movement amount Xs corresponding to the reference movement speed Vs, the high-speed rotation division number (1,000) is selected as the optimum division number [NO in ST13] N.), ST16]. When the designated movement amount X is equal to or less than the resolution for ultra high speed (50 nm), the number of divisions for high speed rotation (1,000) is selected.

  In this embodiment, the division number selection means (81, 82) selects the division number (20) of the motor driver 93 as the optimum division number for the convenience in constructing the apparatus including the division number switching control unit 88. In this case, for example, a single-phase H-level selection signal (effective signal) Ssct is output, and when the division number (1,000) is selected as the optimum division number of the motor driver 93, an L-level selection signal ( Invalid signal) Ssct is output.

  The switching signal generation output means is formed from the division number switching control unit 88 shown in FIG. 6 and receives a selection signal (valid signal) Ssct that is output when the optimum division number (20) of the motor driver 93 is selected. Using this as a trigger signal, for example, a multi-phase H-level division number selection switching control signal (switching valid control signal) Schg for switching control to the super high-speed division number (20) is generated and output to the motor driver 93 (FIG. 8 ST14). In this embodiment, the division number selection switching control signal (switching valid control signal) Schg switches the division number switching control function (division number from 1,000 to 20) of the division number switching control unit 88 as shown in ST14. ) Is treated as a control signal. The division number switching control unit 88 can be formed integrally with the pulse signal control unit 85 described above.

  When the switching signal generation output means (88) receives the selection signal (invalid signal) Ssct output when the optimum division number (1,000) is selected, the switching signal generation output means (88) sets the high-speed division number (1,000). An L level division number selection switching control signal (switching invalid control signal) Schg for return switching control is generated and output to the motor driver 93 (ST16). The division number selection switching control signal (switch invalid control signal) Schg in this case is a control signal for invalidating the division number switching control function (switching the division number from 1,000 to 20) of the division number switching control unit 88. Handled.

  In other words, in this embodiment, the motor driver 93 normally performs the dividing operation with the high-speed division number (1,000... Same as the medium / low-speed division number). Then, the division number switching control function is made effective only when the switching effective control signal (Schg) is input, and in other cases, it is automatically switched back to the normal high-speed division number (1,000). Is formed.

  When the positioning control circuit unit 90 receives the pulse signal Psz having a frequency (fhh) corresponding to the command movement speed from the pulse signal control unit 85, the positioning control circuit unit 90 basically shortens the overall positioning time by the ultra-high speed rotation operation. Function. In other words, the table position at the end of the ultra high speed rotation operation may stop at a position before reaching the accumulated representative read error equivalent position (800 nm) in relation to the command movement amount (target position). In this case, it can be considered that the high-speed rotation operation is complemented until reaching the position corresponding to the accumulated representative read error from the stop position, but this is inevitably referred to as partial slowdown.

  Thus, the positioning control circuit 90 is assumed that the positioning completion position when the ultra-high-speed positioning based on the designated movement amount X is executed is the position before the accumulated representative read error equivalent position (800 nm) (the position before this). In this case, the number of pulses (positioning control signal) obtained by adding one pulse to the number of pulses corresponding to the positioning control signal corresponding to the designated movement amount X can be generated and output to the power applying unit 50.

  For example, as shown in FIGS. 11B and 11C, when the designated movement amount is 1.000010 mm, the number of necessary ultra-high speed position control pulses is 19984.2 [= (1,000,010-800). nm / 50 nm]. This state means that since the super-high-speed position control has ended before the medium-speed position control region, it cannot be smoothly transferred to the medium-speed position control as it is. Therefore, 19,985 pulses are obtained by adding one pulse (rounding up the decimal point). Then, ultra-high-speed positioning can be terminated at a position (760 nm) that has entered the medium-speed position control region by 40 nm [= 50 nm × (1-0.2)]. A quick and smooth takeover can be performed without any adverse effect on the medium speed position control with 1 nm resolution.

  The positioning device having such a configuration operates as follows.

  The operation control unit 80 (CPU 81) reads the positioning command amount (designated movement amount X... Target position) from the RAM 83 in accordance with the command (YES in ST10 in FIG. 8) (ST11), and continues to move speed command value (designated movement speed V). Is read (ST12).

  Then, the division number selection means (81, 82) selects the division number with reference to the division number selection switching information stored in the memory 82M of FIG. 7 and the designated positioning information stored in the work area of the RAM 83. When the designated movement speed V is equal to any of the reference movement speeds Vs and the designated movement amount X is longer than the reference limit movement amount Xs corresponding to the reference movement speed Vs, the number of divisions for super high speed rotation (20 ) Is selected as the optimum number of divisions (YES in ST13).

  For example, when the designated movement amount X is 1.000010 mm and the designated movement speed V is 1.0 mm / sec, the reference limit movement amount Xs is 0.05 mm. Therefore, as shown in FIG. The number of divisions (20) for ultra high speed rotation (20 kHz) is selected (ST14). The selection signal (valid signal) Ssct is output, and the switching signal generation output means (division number switching control unit 88) generates and outputs the division number selection switching control signal (switching effective control signal) Schg to the motor driver 93. Thereby, the number of divisions is switched to the number of divisions for ultra high speed (20). In ST14, the fact that the division number switching control function (1,000 → 20) of the division number switching control 88 is validated is described as “division number switching control unit valid”.

  7 and 11C, when the designated movement amount X is the same (1.0000010 mm) and the designated movement speed V is 2.5 mm / sec, the reference limit movement amount Xs is Since it is 0.020 mm, the division number (20) for ultra-high speed rotation (50 kHz) is selected (YES in ST13, ST14). That is, the division number switching control function (1,000 → 20) of the division number switching control 88 is validated.

  However, even if the designated movement amount X is 1.000010 mm as in the above case, when the designated movement speed V is 0.5 mm / sec, the maximum response frequency of the motor driver 93 is reached as in the conventional example (FIG. 12). And is outside the frame of the division number selection switching information of FIG. That is, as shown in FIG. 11A, the division number (1,000) for high speed rotation (500 kHz) is selected (NO in ST13, ST16). The division number may remain the high-speed division number (1,000). In ST16, the fact that the division number switching control function (1,000 → 20) of the division number switching control 88 is invalidated is described as “division number switching control unit invalid”.

  When the super high speed rotation operation is selected (ST14), the operation control unit 80 (CPU 81) corresponds to the designated movement amount (target position) X and the movement speed command value (designated movement speed V) read from the RAM 83 according to the command. A positioning command signal (including designation of the number of pulses and frequency) OPN for super high speed open loop control is output. Upon receiving this command signal OPN, the pulse signal control unit 85 generates and outputs a command pulse signal Psz [number of ultra-high-speed drive pulse signals Pdhh corresponding to the ultra-high-speed rotation frequency fhh and the ultra-high-speed rotation target position (800 nm)]. (ST15). For simplification of description, the description of the above-described one-pulse addition is omitted.

  Then, the positioning control circuit unit 90 sends (passes through) the ultra high speed drive pulse signal Pdhh to the motor driver 93 while switching to the open loop control, and rotates the stepping motor 51 at ultra high speed (ST15). The table 31 moves at a super high speed (2.5 mm / sec) shown in FIG. 11C in the Z direction (eg, the right direction) in FIG.

  During this ultra high speed rotation, the CPU 81 reads the movement displacement amount Psd as the current position (ST18), and is set and stored as corresponding to the ultra high speed rotation deviation allowable value (Eh = Max.800 nm) stored in the RAM 83. It is determined whether or not the ultra-high speed rotation target position (800 nm) has been reached (ST19). In this case, the operation control unit 80 (CPU 81, ROM 82) functions as a movement displacement amount reading control means and a deviation determination means.

  Then, the operation control unit 80 (CPU 81, ROM 82) determines that the movement displacement amount of the table 31 has not reached (1.0001010 mm-800 nm), that is, has not reached the ultra-high speed rotation target position (800 nm) ( If NO in ST19, the division number switching control is enabled (YES in ST20) and the ultra high speed rotation is continued (ST15). If it can be determined that the target position for ultra-high speed rotation (800 nm) has been reached (YES in ST19), the division number switching control function of the division number switching control unit 88 is disabled (ST21) and an open loop A command for switching from control to closed loop control and a positioning command signal (including designation of the number of pulses and frequency) CLSD for medium speed closed loop control are output (ST22 in FIG. 9). Upon receiving this command signal CLSD, the pulse signal control unit 85 generates and outputs a command pulse signal Psz having a medium speed rotation frequency fm.

  On the other hand, when the high speed rotation operation is selected (ST16 in FIG. 8), the operation control unit 80 (CPU 81) causes the high speed corresponding to the designated movement amount (target position) X and the movement speed command value (designated movement speed V). A positioning command signal for open loop control (including designation of the number of pulses and frequency) OPN is output. Upon receiving this command signal OPN, the pulse signal control unit 85 generates and outputs the command pulse signal Psz [the number of high-speed drive pulse signals Pdh corresponding to the high-speed rotation frequency fh and the high-speed rotation target position (800 nm)] (ST17). ).

  Then, the positioning control circuit unit 90 sends (passes through) the high-speed drive pulse signal Pdh to the motor driver 93 while switching to the open loop control, and rotates the motor 51 at high speed (ST17). The table 31 moves at a high speed (0.5 mm / sec) shown in FIG. 11A in the Z direction (for example, the right direction) in FIG.

  During this high-speed rotation, the CPU 81 reads the movement displacement amount Psd as the current position (ST18), and the high-speed rotation set and stored as corresponding to the high-speed rotation deviation allowable value (Eh = Max.800 nm) stored in the RAM 83. It is determined whether or not the target position (800 nm) has been reached (ST19). In this case, the operation control unit 80 (CPU 81, ROM 82) functions as a movement displacement amount reading control means and a deviation determination means.

  Then, the operation control unit 80 (CPU 81, ROM 82) determines that the movement displacement amount of the table 31 has not reached (10 mm-800 nm), that is, has not reached the high-speed rotation target position (800 nm) (ST19 in FIG. 8). If NO, the division number switching control function is disabled (NO in ST20) and high speed rotation is continued (ST17). If it can be determined that the high-speed rotation target position (800 nm) has been reached (YES in ST19), the division number switching control function of the division number switching control unit 88 is currently invalidated, so the invalidation process (ST21). Is passed, and a switching command from open loop control to closed loop control and a positioning command signal for medium speed closed loop control (including designation of the number of pulses and frequency) CLSD are output (ST22 in FIG. 9). . Upon receiving this command signal CLSD, the pulse signal control unit 85 generates and outputs a command pulse signal Psz having a medium speed rotation frequency fm.

  Then, the positioning control circuit unit 90 switches to closed loop control using the movement displacement amount (post-division detection pulse signal Psd) read from the movement displacement amount detection unit 60 (95) as a feedback signal and generates the medium speed drive pulse. The signal Pdm is sent to the motor driver 93 to rotate the stepping motor 51 at medium speed (ST22). The table 31 is moved at a medium speed (0.002 mm / sec) shown on the right side of FIGS. 11C and 11A and positioned toward a target position for medium speed rotation.

  During the medium speed rotation, the CPU 81 continuously reads the movement displacement amount Psd and sets the target position (63−63) set and stored in the RAM 83 as corresponding to the medium speed rotation allowable value (Em = ± 63 nm). α) It is discriminated whether or not it is within nm (ST23, ST24). Also in this case, the operation control unit 80 (CPU 81, ROM 82) functions as a movement displacement reading control unit and a deviation determination unit.

  When it is determined that the target position (63-α) nm has not been reached (NO in ST24), the medium speed rotation is continued (ST22). If it can be determined that it has reached (YES in ST24), the operation control unit 80 (81) outputs a positioning command signal (including designation of the number of pulses and frequency) CLSD2 for low-speed closed loop control. The pulse signal control unit 85 that has received the command signal CLSD2 generates and outputs a command pulse signal Psz having a low-speed rotation frequency fl.

  Then, the positioning control circuit unit 90 drives at low speed while switching to closed loop control using the movement displacement amount (post-division detection pulse signal Psd) read from the movement displacement amount detection unit 60 (95) as a feedback signal. The pulse signal Pdl is sent to the motor driver 93 to rotate the motor 51 at a low speed (ST25 in FIG. 9). The table 31 is moved at a low speed (0.0002 mm / sec) shown on the right side of FIGS. 11C and 11A, and is positioned for low-speed rotation, that is, toward the final target position (± 1 nm).

  During this low-speed rotation, the CPU 81 continuously reads the movement displacement amount Psd and determines whether it is within the deviation allowance for low-speed rotation (El = ± 1 nm) stored in the RAM 83 (ST26, ST32). . Also in this case, the operation control unit 80 (CPU 81, ROM 82) functions as a movement displacement reading control unit and a deviation determination unit.

  If it is determined that the deviation is not within the tolerance (El = ± 1 nm) (NO in ST32), the low-speed rotation is continued (ST25). If it is determined that the deviation is within the allowable value (El = ± 1 nm) (YES in ST32), the positioning is terminated.

  Here, the apparent generation signal ignoring means and the operation related thereto (ST27 to ST31 in FIG. 9) will be described in detail.

  As described above, since the value of the low-speed rotation frequency fl is selected to be low speed (0.0002 mm / sec), that is, 200 Hz, which can prevent overrun, it is ensured that the amount of movement displacement at the end of low-speed rotation drive. Positioning can be stopped with high accuracy (1 nm) corresponding to the minimum resolution (1 nm) of the detector 60 and the amount of movement of the drive pulse signal Pdl (1 nm / 1 pulse).

  However, this conventional concept is effective (adapted) when establishing a positioning device with a positioning accuracy of about 10 nm [for example, the device of the previous proposal (Patent Document 6)]. In the case of a guaranteed device, it can be said that it is out of conformity.

  According to test studies prior to the creation of the present invention, it has been recognized that there are instability factors related to the entry of inherent disturbances due to their high precision (1 nm or less). That is, there is a situation in which the final positioning accuracy (1 nm or less) cannot be guaranteed stably and reliably. That is, hunting occurs mainly with positioning accuracy (1 nm or less) and final positioning cannot be performed, positioning ends with an accuracy exceeding ± 1 nm, and after positioning is finished, the final positioning accuracy (1 nm or less) varies. It is a situation that ends up.

  The cause is that subtle mechanical vibration may occur at the end of the low-speed rotation drive by the closed loop control, and the high displacement (1 nm) moving displacement detector 60 detects the vibration as a displacement and performs positioning. The control circuit unit (deviation counter) 90 is to generate and output a low-speed rotation drive pulse signal Pdl for canceling the deviation. This low-speed rotation drive pulse signal Pdl for canceling the deviation is an apparent occurrence signal that is not included in the original control contents, and is not only unnecessary but also harmful in positioning control.

  Thus, studies were made to realize a structure in which mechanical vibration does not occur at the end of low-speed rotation driving. For example, a heavy anti-vibration rubber is attached to the important part of the stage 10. For example, the mechanical rigidity of the stage 10 (11, 31, etc.) is increased. However, all have drawbacks that lead to increased structural complexity, larger equipment, and higher costs. Even if these drawbacks are accepted or the speed for low-speed rotation is set to a much lower value, it is difficult to completely eliminate the mechanical vibration.

  However, unless the unique and special problems are solved, the spread of the apparatus cannot be achieved. Therefore, as a result of detailed verification on the premise that mechanical vibration is generated at the end of low-speed rotation driving, it has been found that there is a certain correlation between the amplitude of the mechanical vibration generated at the end of positioning and the vibration frequency.

  Specifically, in the structure of the stage 10 according to this embodiment (particularly, the size of the table 31... Mass 0.5 kg), when the amplitude wz in the Z direction exceeds ± 1 nm, the vibration frequency fmz exceeds 25 Hz. It was at the time of value. The maximum load is 10 kg as described above. That is, at 25 Hz or less, an amplitude exceeding ± 1 nm was not recognized. Even if the stage 10 (table 31) centering on this is enlarged (for example, the planar shape of the table 31 is 200 mm × 200 mm) or downsized (for example, 100 mm × 100 mm), it is about this extent. With respect to the difference in size (structure), an amplitude exceeding ± 1 nm was not recognized. It seems that the increase / decrease amount of the table mass is very small with respect to the maximum load of 10 kg.

  In view of this, the present inventors have devised a technique for specifying the above-described apparent generation signal (apparent motor rotation control signal) and excluding it by hardware or / and software. In this embodiment, the apparent signal ignoring means 100 is provided and constructed so as to ignore the apparent generation signal (apparent motor rotation control signal) when mechanical vibration is detected (not output to the motor driver 93 side). is there.

  The apparent signal ignoring means 100 is composed of a vibration frequency detecting means 101, a frequency comparison discriminating means 102 and a signal output blocking control means 103 provided in the positioning control circuit section 90, and is generated on the stage 10 during low speed rotation. This is means for ignoring an apparent generation signal (one apparent motor rotation control signal... Pdl) generated due to mechanical vibration.

  The vibration frequency detection means 101 detects the mechanical vibration frequency fmk of the stage 10 during low-speed rotation (ST28 in FIG. 9). In this embodiment, the mechanical vibration frequency fmk is obtained by triggering with the rising pulse of the output signal of the deviation counter at the end of low-speed rotation driving (timing details will be described later) and measuring the time of one period of vibration. Is detected. Therefore, the vibration frequency detecting means 101 is shown in another form [for example, the vibration sensor (101) provided on the table 31 (or base 11) side... ], It can be easily implemented and can be realized at low cost, and its reliability is very high.

  The frequency comparison discriminating means 102 compares and discriminates the read reference frequency (set frequency) fs and the detected vibration frequency fmk (ST29). It is determined that the detected vibration frequency fmk is not a frequency exceeding the set reference frequency fs (25 Hz) (NO in ST30). A YES determination is also made when vibration cannot be detected and cannot be detected. The reference frequency (set frequency) is taken into the positioning control circuit unit 90 directly from the CPU 81 (not shown in FIG. 6) or through the pulse signal control unit 85.

  If NO is determined and it is determined that the current value is not within the allowable deviation value (El = ± 1 nm) (NO in ST32), low-speed rotation driving is continued (ST25). If it can be determined that the deviation is within the allowable value (El = ± 1 nm) (YES in ST32), the positioning is terminated.

  Here, when the frequency comparison determination means 102 determines that the detected vibration frequency fmk is a frequency exceeding the set reference frequency fs (YES in ST30), the signal output prevention control means 103 operates. That is, the motor rotation control signal Pdl (apparent motor rotation control signal) for low-speed rotation generated by the positioning control circuit unit 90 is prevented from being output to the motor driver 93 (ST31). Therefore, hunting can be prevented.

  By the way, from the viewpoint of shortening the positioning time, during the low-speed rotation drive, even if mechanical vibration exceeding 25 Hz occurs for some reason (induction or addition), the motor rotation control signal (Pdl) is output. The motor rotation should not be interrupted by blocking. In addition, operating the vibration frequency detection means 101 and the frequency comparison determination means 102 at any time during low-speed rotation driving (ST28, ST30) is also disadvantageous in increasing the data processing load.

  Such a situation occurs when the vibration frequency detection means 101 and the frequency comparison determination means 102 are constructed with a simple circuit (for example, an OR circuit) using circuit elements in the positioning control circuit unit 90, during ultra-high speed motor rotation control, Even during the high-speed motor rotation control and the medium-speed motor rotation control, the output of the motor rotation control signals (Pdhh, Pdh, Pdm) may be blocked, and there is a possibility that the motor rotation may be interrupted. In addition, if it returns to the background origin, it does not become familiar with the idea that aims to clear out the problems associated with mechanical vibration that occurred at the end of positioning by low-speed rotation control.

  Here, the frequency detection timing detection means 105 is provided, and is formed so that it can proceed to ST28 to ST31 after it is confirmed that the frequency detection timing has been reached (YES in ST27). In this embodiment, the frequency detection timing is set as the end of positioning by low-speed rotation (for example, when the tenth low-speed drive pulse signal Pdl counted from the end is output). It may be selected and set at the time when the first (or second) and subsequent low-speed drive pulse signal Pdl is output from the end.

  The case where the frequency detection timing detection unit 105, the frequency comparison determination unit 102, and the signal output prevention control unit 103 are formed by hardware (positioning control circuit unit 90) has been described above. You may form from ROM82 which stored the control program, and CPU81 which performs this. In this case, the detection signal of the vibration frequency detecting means 101 may be formed so as to be readable by the CPU 81.

  Further, the frequency detection timing detection means (105) can be formed so as to detect and detect a frequency change accompanying vibration of other electrical signals in the positioning drive control unit.

  The method or means for ignoring the apparent generation signal may be implemented by other methods or means. For example, when mechanical vibration is detected, all or a part of the movement displacement detector 60 is locked to hold the value of the divided detection pulse signal Psd. When the detected vibration frequency is 25 Hz or less, low speed rotation is performed. For example, a low-pass filter that allows the drive pulse signal Pdl to pass therethrough is provided in the positioning control circuit unit 90.

  In the positioning device according to this embodiment, referring to FIG. 8, FIG. 10, and FIG. 11C, the table 31 is super-high speed with the same value as the allowable maximum of the device (51 etc.) in the Z direction by open loop control. It is moved at (2.5 mm / sec). When the designated movement amount X is 1.00010 mm, the high-speed position control time in the conventional example (FIG. 12) is about 1.998 sec, whereas in the present invention [FIG. The control time is about 0.3997 sec, and can be completed in about 1/5 time. In other words, the speed was increased about 5 times.

  In the actual operation, when the evaluation areas with a resolution of 1 nm are arranged at intervals of 5 mm, in the case of the conventional example, the transition to the next evaluation area takes about 10 seconds, but in the case of the present invention, about 2 Since it can be shifted in seconds, the evaluation work efficiency can be greatly improved. You can clear your free time. In other words, considering the above-described movement (return) of the table movable range (50 mm), a dramatic time reduction can be achieved from about 100 seconds to about 20 seconds in the conventional example.

  In addition, since the specified moving speed can be set to an arbitrary moving speed within a predetermined range (over 0.5 to 2.5 mm / sec), the practicality has been dramatically improved. That is, not only the ultra high speed (2.5 mm / sec) shown in FIG. 11 (C) but also, for example, the mobile operation specifying the ultra high speed (1.0 mm / sec) shown in FIG. 11 (B) can be performed.

  In the case of FIG. 11A, the high-speed position control time is 1.998 sec, which is the same as in the case of the conventional example (FIG. 12). That is, the conventional usage mode can also be selected.

  In both ultra-high speed position control and high-speed position control, closed-loop control is performed when the current position of the table detected using the moving displacement amount detection unit 60 having a minimum resolution of 1 nm falls within the set target position corresponding to the deviation allowable value (800 nm). Is switched to medium speed (0.002 mm / sec). Subsequently, when the current value enters the set target position [(63-α) nm] corresponding to the deviation tolerance (± 63 nm), the low speed (0.0002 mm / sec) with no concern for overrun while maintaining the closed loop control. It is moved with. Therefore, the time required to cancel the error E (800 nm) of the table moving mechanism unit 40 and complete the high-precision positioning of ± 1 nm can be greatly shortened (0.68 seconds = 0.37 + 0.31). The required time when the error cancellation step is performed only by the low-speed rotation drive is 4.00 seconds (= 800/200).

  Incidentally, since the entire region is controlled by continuous motor drive, the disadvantages of the switching structure between coarse movement (screw shaft drive) and fine movement (piezo actuator drive) can be eliminated. That is, the amount of movement displacement can be increased, the movement time by continuous driving can be shortened, the ball screw shaft 41 can be used in an inclined state or a vertical state, and it can be used in a vertical state and in a state where the load is increased.

  In addition, when a large mechanical vibration exceeding ± 1 nm is generated in the stage 10 (11, 31), the apparent generation signal ignoring means 100 operates, and the apparent motor rotation control signal (generated by the positioning control circuit 90) ( The low-speed rotation drive pulse signal Pdl) is prevented from being output to the motor driver 55 side. If necessary, after the mechanical vibration is converged, the last drive pulse signal Pdl for low-speed rotation is output and driven within ± 1 nm. Therefore, stable positioning control can be reliably ensured and high accuracy (± 1 nm) positioning can be ensured regardless of where and when it is used.

  Since the apparent generation signal ignoring means 100 operates just before the end of the low-speed rotation driving, it is possible to eliminate unnecessary motor rotation interruption, prolonged control time due to hunting, and unstable operation. Furthermore, the damper 28 also promotes a mechanically equivalent effect.

  Thus, according to this embodiment, the stepping motor 51 is directly connected to the screw shaft 41, and the motor driver 93 is divided into a high-speed rotation division number (1,000) and an ultra-high-speed rotation division number (20). Can be selectively switched, and the optimum number of divisions for the actual positioning operation can be selected by using the designated positioning information and the division number selection switching information, and the division number of the motor driver 93 can be switched to the selected division number. Thus, since the control signal Pdhh for ultra-high speed rotation by open loop control is configured to be output, it is possible to execute ultra-high speed positioning control that is much faster than the high-speed positioning control by open loop control. Therefore, high-precision positioning of 1 nm or less can be performed stably at an ultra-high speed, and a small and lightweight table positioning apparatus can be provided.

  Further, since the screw shaft 41 is a ball screw shaft with a lead of 1 mm and the signal division number of the signal dividing circuit 95 is selected to be 2,000, it is possible to achieve further cost reduction and operation stabilization.

  Further, since the step angle of the stepping motor 51 is selected to be 0.36 degrees, it is effective in reducing the number of divisions of the motor driver 93. It is also useful for cleaning the speed reducer.

  Since the number of divisions for high speed rotation of the motor driver 93 is 1,000 and the number of divisions for ultra high speed rotation is 20, operation that switches between high speed and ultra high speed without imposing an excessive burden on the motor driver 93 is possible. it can.

  Since the division number selection switching information is information that associates the reference movement speed Vs until the motor driver 93 reaches the maximum response frequency and the reference movement amount Xs, the frequency operation below the maximum response frequency of the motor driver 93 is performed. High-speed movement and ultra-high-speed movement can be switched stably while securing, and the adaptability to the driving mode is wide.

  Further, the division number selection means (81, 82) makes the high-speed rotation division number (1,000) effective when the designated movement amount X is shorter than the reference movement amount Xs corresponding to the reference movement speed Vs [ultra-high speed. When the rotation division number (20) is invalid] and longer than the reference movement amount, the super-high-speed rotation division number (20) is effective, so that the positioning operation with the designated movement speed and movement amount can be performed, and Stable positioning is possible regardless of the specified value.

  Further, when it is assumed that the super-high-speed positioning completion position is a position before reaching the position corresponding to the accumulated representative read error, a positioning control signal having the number of pulses obtained by adding one pulse to the positioning control signal is generated and output to the power applying unit 50. Therefore, it is possible to quickly take over from the ultra high speed moving operation to the medium speed moving operation, and it is effective for shortening the time until the final positioning is completed.

  Since the mechanical damper 28 is connected to the rotating shaft of the stepping motor 51, mechanical vibration during low-speed moving operation can be absorbed, and more stable positioning can be achieved.

  Since the positioning operation in which the movement amount and the movement speed are changed within a predetermined range can be performed, the application range can be greatly expanded as compared with the conventional example (the movement speed cannot be changed).

  An apparent signal ignoring means 100, a vibration frequency detecting means 101 for detecting a mechanical vibration frequency during low-speed rotation, a frequency comparison determining means 102 for determining whether or not the detected vibration frequency exceeds a set reference frequency, Since it comprises the signal output blocking control means 103 that blocks the output of the motor rotation control signal (Pdl) for low-speed rotation, it is possible to prevent disturbance intrusion without waste and perform more reliable and stable positioning. Implementation of the means is easy.

  Since the reference frequency is selected to be 25 Hz, the detection is easier and quicker. Further, since the setting can be changed using the setting unit 71, the adaptability to the structure and operation items of the table moving mechanism unit 40 is wide, and the frequency comparison / determination means 102 is formed so that it can be discriminated just before the end of positioning by low-speed rotation. In addition, useless motor rotation interruption and hunting can be prevented, and the data processing load can be reduced.

  Further, since the movement displacement amount detection unit 60 is housed in the stage 10, it is possible to easily perform moire adjustment and the like from the outside without disassembling and removing the table 31 from the base 11, and in a sealed state during use. Therefore, it is possible to prevent dust from entering and sticking.

  In addition, since the third optical gratings 63T are gathered at one place and are arranged close to each other in the length direction of the index scale 63, the apparatus size in the Z direction can be further reduced, and the first optical grating 61F is included. Parallelism to the plane can be established more easily and quickly.

10 stage 11 base 28 damper 31 table 40 table moving mechanism 41 screw shaft (ball screw shaft)
DESCRIPTION OF SYMBOLS 50 Power provision part 51 Stepping motor 55 Motor driver 60 Movement displacement amount detection part 61 Main scale 63 Index scale 70 Positioning drive control unit 80 Operation control part 81 CPU (division number selection means)
82 ROM (division number selection means)
82M Memory 88 Division number switching control section (switching signal generation output means)
90 Positioning control circuit (with deviation counter)
93 Motor driver 95 Signal dividing circuit 100 Apparent signal ignoring means Z Base line Pd Drive pulse signal (motor rotation control signal)
Pdhh Ultra-high-speed drive pulse signal (motor rotation control signal for ultra-high-speed rotation)
Pdh High-speed drive pulse signal (motor rotation control signal for high-speed rotation)
Pdm Medium-speed rotation drive pulse signal (Medium-speed rotation motor rotation control signal)
Pdl Low-speed drive pulse signal (low-speed motor rotation control signal)
Pdz Apparent drive pulse signal (apparent motor rotation control signal)
Detection pulse signal after Psd division (movement displacement detection signal)
Ssct selection signal Schg Division number selection switching control signal

Claims (8)

It includes a table moving mechanism that uses a screw shaft whose lead is 1 mm or less and can move the table relative to the base, and a stepping motor and motor driver connected to the screw shaft, and rotates the screw shaft based on a motor rotation control signal. A power applying unit that applies power to the table moving mechanism unit to drive and move the table by 1 nm at a minimum, and includes three optical gratings and a signal dividing circuit, and the bright and dark lines of each optical grating are 2 μm, respectively. In addition, a displacement detection unit for detecting a displacement displacement of the table by generating and outputting a displacement displacement detection signal of 1 nm per pulse, for high speed rotation by open loop control, for medium speed rotation by closed loop control, and low speed The motor rotation control signal for rotation can be switched and output in this order, and the table is positioned at the target position A positioning control circuit for generating and outputting a positioning control signal to the power applying unit, and an apparent signal ignoring means for ignoring an apparent motor rotation control signal generated due to mechanical vibration generated in the device component during low-speed rotation; In the table positioning device provided,
Directly connecting the stepping motor to the screw shaft;
Selectively switchably forming the division number of the motor driver and the high speed division number and ultra high speed for the number of divisions,
Memory for storing division number selection switching information for selecting either high-speed rotation division number or ultra-high-speed rotation division number, designated positioning information specified during actual positioning operation, and division number selection stored in memory Using the switching information, a division number selection means for selecting the optimum division number of the motor driver for the actual positioning operation, and a division number selection switching signal for switching to the selected optimum division number are generated in the motor driver. Switching signal generation output means for outputting,
The positioning control circuit unit is configured to be able to output a motor rotation control signal for ultra high speed rotation instead of the motor rotation control signal for high speed rotation by open loop control,
A table positioning device formed so as to be capable of performing ultra-high-speed positioning control that is faster than the high-speed positioning control by the open loop control. The table positioning device of claim 1,
A table positioning apparatus, wherein the screw shaft is a ball screw shaft having a lead of 1 mm, and the signal division number of the signal division circuit is selected to be 2,000. In the table positioning device according to claim 1 or 2,
A table positioning device in which a step angle of the stepping motor is selected to be 0.36 degrees. In the table positioning apparatus in any one of Claims 1-3,
The table positioning device, wherein the number of divisions for high-speed rotation is 1,000 and the number of divisions for ultra-high-speed rotation is 20. In the table positioning apparatus in any one of Claims 1-4,
A table positioning apparatus in which the division number selection switching information is information relating a reference moving speed and a reference limit moving amount until the motor driver reaches the maximum response frequency. The table positioning device according to claim 5, wherein
If the designated moving speed is equal to any of the reference moving speeds and the designated moving amount is shorter than the reference moving amount corresponding to the reference moving speed, the dividing number selecting means is the high-speed rotation dividing number. Can be selected as the optimal number of divisions, and when the designated movement amount is longer than the reference movement amount corresponding to the reference movement speed, the division number for ultra-high speed rotation is formed to be selectable as the optimum division number. Table positioning device. In the table positioning apparatus in any one of Claims 2-6,
When it is assumed that the positioning completion position when the positioning control circuit unit performs ultra-high-speed positioning based on the designated movement amount is a position before reaching the position corresponding to the accumulated representative read error, the positioning corresponding to the designated movement amount A table positioning device configured to be capable of generating and outputting a pulse number obtained by adding one pulse to a pulse number corresponding to a control signal to the power applying unit. In the table positioning device according to any one of claims 2 to 7,
A table positioning device in which a mechanical damper is connected to a rotating shaft of the stepping motor.

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