JP2016150398A - Drive device, stage device, and industrial machinery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive device advantageous in the point of a resource required therefor.SOLUTION: A drive device comprises a screw member and an engaging member engaging with the screw member and moves an object by the relative movement between the screw member and the engaging member. The drive device contains a scale and a detector, and has an encoder for measuring the position of the object by reading the scale by the detector. The drive device is characterized in that the scale is provided in the screw member.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a drive device, a stage device, and an industrial machine.

  As a drive device having a screw feed mechanism using a ball screw or the like, generally, as shown in FIG. 6, a rotary encoder 1012 is arranged at the end of a drive motor 1011 as a drive source for speed control and position control. A driving device 1000 for performing is known. The driving device 1000 includes a ball screw 1001, a nut 1002 that engages with the ball screw 1001, a coupling 1013 that connects the ball screw 1001 and the driving motor 1011, and a carriage 1007. Here, the nut 1002 is provided (fixed) on the carriage 1007.

  Further, as a drive device that performs positioning using a linear encoder, a drive device 2000 as shown in FIGS. 7A and 7B is generally known. 7A is a front view of the drive device 2000, and FIG. 7B is a cross-sectional view taken along line MM of the drive device 2000. The driving device 2000 includes a ball screw 2001, a nut 2002 that engages with the ball screw 2001, a coupling 2013 that connects the ball screw 2001 and a driving motor 2011 that is a driving source, and a carriage 2007 that is supported by the nut 2002. Have The drive device 2000 also includes a linear guide rail 2015 that guarantees a linear trajectory of the carriage 2007, a scale 2017, and a head 2006 that reads the scale 2017 (pattern thereof). The head 2006 and the scale 2017 constitute a linear encoder for position measurement.

  As shown in FIGS. 6, 7 (a), and 7 (b), in a drive device having a screw feed mechanism using a ball screw, a rotary encoder or a linear encoder is often used as a position measuring device. In order to improve the accuracy of such an encoder, for example, the number of divisions of the scale pattern of the rotary encoder or linear encoder may be increased (the resolution of the scale may be increased). However, there is a physical limit to increasing the number of divisions of the scale pattern. Further, as shown in FIGS. 7 (a) and 7 (b), when the scale of the linear encoder is arranged, it is necessary to secure a space for arranging the scale and to ensure the positioning accuracy of the carriage. There is a need for attachment (placement) constraints to reduce errors. In order to increase the reduction ratio of the ball screw, it can be dealt with by shortening the pitch of the ball screw, but minimization of the pitch of the ball screw has a physical limit.

  Patent Document 1 discloses a technique for detecting the entrance and exit (movement and rolling) of a ball in a nut engaged with a ball screw with a pair of proximity sensors in order to save space. However, in Patent Document 1, the ball in the nut is regarded as a scale, but the measurement resolution is limited by the diameter of the ball, so that high resolution is difficult compared to the encoder described above. Further, in Patent Document 2, as an example of a cylinder stroke sensor, a magnetic scale is provided on a piston rod in a spiral shape, and a plurality of sensors (detection elements) are arranged at equal intervals so as to surround the piston rod. It is disclosed to provide on the circumference.

Japanese Patent Publication No. 03-021042 JP 2010-255715 A

  In Patent Document 2, a magnetic scale is provided on the piston rod in a spiral shape, and a sensor is provided on the cylinder. In order to measure the movement position of the piston rod, a plurality of piston rods are provided so as to surround the piston rod. A sensor is required. Therefore, an increase in resources (number of parts or parts cost, space, calculation load, etc.) required for the apparatus is caused.

  An object of the present invention is to provide a driving device that is advantageous in terms of the resources required.

  In order to achieve the above object, a drive device according to one aspect of the present invention includes a screw member and an engagement member that engages with the screw member, and the drive device is provided between the screw member and the engagement member. A driving device for moving an object by relative movement, comprising a scale and a detector, and having an encoder for measuring the position of the object by reading the scale with the detector, The screw member is arranged.

  Further objects and other aspects of the present invention will become apparent from the preferred embodiments described below with reference to the accompanying drawings.

  According to the present invention, for example, it is possible to provide a drive device that is advantageous in terms of the resources required for it.

It is the schematic which shows the structure of the drive device as 1 side surface of this invention. It is a figure for demonstrating the detailed structure of the ball screw of a drive device shown in FIG. 1, a nut, and an encoder. It is a figure for demonstrating the method of drawing a scale with the laser marker on the axis | shaft of a ball screw. It is a figure which shows an example of a structure of the scale of an encoder. It is the schematic which shows the structure of the stage apparatus as 1 side surface of this invention. It is the schematic which shows an example of a structure of a general drive device. It is the schematic which shows an example of a structure of a general drive device.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings. In addition, in each figure, the same reference number is attached | subjected about the same member and the overlapping description is abbreviate | omitted.

  FIG. 1A and FIG. 1B are schematic views showing a configuration of a drive device 1 as one aspect of the present invention, and FIG. 1A is a front view of the drive device 1. FIG. 1B is an LL cross-sectional view of the driving device 1. The driving device 1 drives an object to be driven using a precision ball screw linear motion transmission mechanism. The drive device 1 includes a ball screw 11, a nut 12 that engages with the ball screw 11, a drive motor 13, a coupling 14, a carriage (base) 15, a linear guide rail 16, an encoder 17, and a control. Part 20.

  The drive motor 13 is a drive source, and a general DC motor is used in the present embodiment. The type of the drive motor 13 can be selected according to the application of the drive device 1, and the drive motor 13 is not limited to the DC motor.

  The coupling 14 connects the ball screw 11 and the drive motor 13. The carriage 15 is fixed (fastened) to the nut 12 and holds an object to be driven. The linear motion guide rail 16 is a rail member that guarantees a straight track of the carriage 15.

  The encoder 17 includes a scale 18 and a head (detector) 19, and the scale 18 is read by the head 19 to measure the position of the nut 12 and output a measurement signal. The head 19 is disposed on the nut 12 or the carriage 15 fixed to the nut 12 so as to face the scale 18 at a predetermined distance and a predetermined angle. Here, the predetermined angle is an angle substantially equal to the torsion angle of the threaded portion of the ball screw 11. In the present embodiment, the head 19 includes a plurality of detection elements arranged along a direction that forms a torsion angle of the ball screw 11 with respect to a plane including the axis of the ball screw 11, and through the plurality of detection elements. A plurality of marks included in the scale 18 are detected.

  The control unit 20 includes a CPU, a memory, and the like, and controls the entire drive device 1 (operation). For example, the control unit 20 performs feedback control on the drive motor 13 based on the measurement signal from the encoder 17.

  A detailed configuration of the ball screw 11, the nut 12, and the encoder 17 will be described with reference to FIG. In this embodiment, the encoder 17 is an absolute encoder. The ball screw 11 is a screw member in the linear motion transmission mechanism. The pitch and the screw diameter of the ball screw 11 are selected according to the driving force, the driving stroke, and the driving stroke. The ball screw 11 can be replaced with various screw feed members (feed members) such as trapezoidal screws and splines (ball splines). The nut 12 is an engagement member that can engage with the shaft (side surface of the threaded portion) 11 a of the ball screw 11 and drive the object.

  A scale 18 of the encoder 17 is formed (arranged) on the shaft 11 a of the ball screw 11. In this embodiment, the scale 18 of the encoder 17 is spirally (continuously) formed on the shaft 11a of the ball screw 11, but may be formed on a part of the shaft 11a. The scale 18 is not the groove portion 11b with which the nut 12 contacts but the portion other than the groove portion 11b, that is, the portion where the nut 12 does not contact (the non-groove portion along the groove portion 11b). ) 11c. Thereby, it is possible to prevent the scale 18 from being worn due to the contact between the shaft 11a of the ball screw 11 and the nut 12. However, it is not forbidden to form the scale 18 in the groove portion 11b of the shaft 11a of the ball screw 11.

  Examples of a method for forming the scale 18 of the encoder 17 on the shaft 11a of the ball screw 11 include a method of drawing the scale 18 with a laser marker and a method of drawing the scale 18 with non-erasable ink using an ink jet printer. In this embodiment, the scale 18 of the encoder 17 is a cyclic code type ternary gradation scale for an absolute encoder. Such a scale 18 can be realized by drawing a gray scale pattern of two or more values that can be read (detected) by the head 19 using a gradation matrix with a laser marker.

  Here, with reference to FIG. 3, the method of drawing the scale 18 with the laser marker on the axis | shaft 11a of the ball screw 11 is demonstrated concretely. First, the ball screw 11 is supported at the shaft end by the support portion. When the ball screw 11 is long, an intermediate support portion may be provided to reduce the axial deflection of the ball screw 11. It is desirable that the support portion that supports the ball screw 11 supports the ball screw 11 so that it can be rotated by θ and the rotation angle can be controlled. In FIG. 3, a servo motor is connected to the shaft end of the ball screw 11 via a joint.

  A laser marker head for performing laser drawing is supported (fixed) movably in the X, Y, and Z axis directions on a laser marker head support including a translational triaxial moving stage. The laser marker head is disposed at a position corresponding to the axis 11a (the portion 11c on which the scale 18 is drawn) of the ball screw 11. By irradiating the laser beam from the laser marker head to the shaft 11a of the ball screw 11 while interlocking the translational driving of the laser marker head and the rotational driving of the ball screw 11, the scale 18 of the encoder 17 is sequentially changed. draw.

  With reference to FIG. 4A, FIG. 4B, and FIG. 4C, the configuration of the scale 18 (pattern) of the encoder 17 will be specifically described. As shown in FIG. 4A, the scale 18 has a one-track absolute scale pattern composed of one ternary gradation track. The ternary gradation is realized by arranging the gratings of the reflective part and the non-reflective part at equal intervals, and further selectively reducing the reflectance of the reflective part. Thus, absolute position information can be given depending on the magnitude of the reflectance.

  The intermediate value portion in which the reflectance of the reflecting portion is selectively lowered can be formed by the following method. Assuming that the pattern width of the reflecting portion is several tens of μm and the line width by laser drawing is several μm, in order to obtain an intermediate value portion, a plurality of parallel lines are formed on the reflecting portion as shown in FIG. Drawing may be performed, or a grid-like line may be drawn as shown in FIG. However, the present invention is not limited to these, and various shape diagrams such as a dotted shape, a polygonal shape, and a circular shape may be drawn on the reflecting portion, and the reflectance of the reflecting portion may be reduced to form the intermediate value portion.

  Returning to FIG. 2, the head 19 for reading the scale 18 is arranged on the nut 12, specifically, on the axis of the ball screw 11. As the ball screw 11 rotates, the nut 12 engaged with the ball screw 11 moves linearly. At this time, the scale 18 moves relative to the head 19 as the ball screw 11 rotates. In other words, the object is moved by the relative linear motion between the ball screw 11 and the nut 12 due to the relative rotation between the ball screw 11 and the nut 12. Accordingly, by reading the scale 18 with the head 19, the moving distance, that is, the position of the nut 12 can be measured.

  In the present embodiment, the encoder 17 is an optical encoder, but is not limited to this. The encoder 17 may be any system that can arrange the scale 18 on the shaft 11a of the ball screw 11, and may be a magnetic encoder, for example. The encoder 17 is an absolute encoder in this embodiment, but may be an incremental encoder. In this case, the scale 18 includes an origin mark (start code) such as a depression.

  The operation of the drive device 1 in this embodiment will be described. First, the control unit 20 is instructed about the moving speed and moving amount of the carriage 15. The control unit 20 supplies power to the drive motor 13 based on the moving speed and moving amount of the carriage 15. At this time, the control unit 20 supplies power to the drive motor 13 based on a change in gradation of the scale 18 read by the head 19 of the encoder 17 in order to move the carriage 15 to a predetermined position at a predetermined speed. To control.

  The ball screw 11 in the present embodiment has an outer diameter of 12 mm and a pitch of 8 mm, and one round of the shaft 11a of the ball screw 11 is about 38 mm. If the scale length of the scale 18 is 30 m, the total number of rotations of the ball screw 11 can be 796, and the movement of the carriage 15 can be controlled within a stroke range of about 6.3 m.

  In this embodiment, instead of using a rotary encoder attached to the drive motor 13 to control the drive motor 13, the scale 18 arranged on the shaft 11a of the ball screw 11 is read by the head 19 to detect the rotational speed and drive. The motor 13 can be controlled. In the present embodiment, since the encoder 17 is an absolute encoder, an origin sensor and a limit sensor are not required, and a return process (such as origin detection) after the power supply is stopped is also unnecessary.

When a rotary encoder is used as in the prior art, a backlash in coupling, a torsion error of a drive motor, and the like are added, so that the carriage cannot be accurately positioned. On the other hand, in the present embodiment, since the drive motor 13 is controlled using the measurement result of the encoder 17 arranged in the vicinity of the carriage 15, the direct position of the carriage 15 can be measured. Further, by arranging the scale 18 on the shaft 11a of the ball screw 11, a space for arranging a linear scale or the like for positioning the carriage 15 becomes unnecessary. Furthermore, the scale length of the scale 18 is 1 / [cos [tan ⁻¹ {pitch of the ball screw 11 / (π × axis diameter of the ball screw 11)}]] times the moving distance of the carriage 15. Can do. Therefore, in this embodiment, a finer scale pitch can be obtained compared to the case where a linear scale having the same scale pitch as that of the scale 18 is arranged. Therefore, the carriage 15 is highly accurate based on the measurement result of the encoder 17. Can be positioned. Further, since the ball screw 11 transmits drive to the carriage 15, it is generally disposed at the center of gravity of the moving body, and the head 19 of the encoder 17 is disposed at a position closest to the center of gravity. , Abbe error can be reduced (minimized).

  In this embodiment, by arranging the scale 18 on the shaft 11a of the ball screw 11, precise speed control and positioning control of the carriage 15 (nut 12) can be performed without using an encoder for driving motor or a linear scale for positioning. Is possible. Further, by arranging the scale 18 on the shaft 11a of the ball screw 11, the scale pitch viewed from the carriage 15 is subdivided even if the scale pitch is equal to that of the prior art, and the resolution of the encoder 17 can be improved. . Furthermore, it is not necessary to arrange a linear scale as described in the prior art. Therefore, according to the drive device 1 of the present embodiment, both space saving and high accuracy can be achieved.

  An application example of the driving device 1 will be described with reference to FIG. If the encoder 17 included in the drive device 1 is an absolute encoder, the drive device 1 does not necessarily require an operation for detecting the origin (reference position). Therefore, the drive device 1 is useful in various devices such as robots, transportation, machining, processing, measurement, and manufacturing machines or devices (industrial machines or processing devices that process objects). However, as described above, the encoder 17 included in the drive device 1 may be an incremental encoder (having or using an origin detection function as necessary) depending on the application. Here, an application example to a stage apparatus (XY stage) included in a lithography apparatus typified by an exposure apparatus will be described. FIG. 5 is a schematic diagram showing a configuration of a stage apparatus 500 as one aspect of the present invention.

  The stage device 500 is configured to be movable while holding a substrate as an object. As shown in FIG. 5, the stage device 500 includes a Y-axis motor 509 used for driving the stage 508 in the Y-axis direction and an X-axis motor 512 used for driving the stage 508 in the X-axis direction. Here, each of the Y-axis motor 509 and the X-axis motor 512 includes the drive device 1 described above.

  The lithography apparatus is an apparatus for forming a pattern on a substrate, and is embodied as, for example, an exposure apparatus, a drawing apparatus, or an imprint apparatus. For example, the exposure apparatus forms a (latent image) pattern on a substrate (upper resist) using (extreme) ultraviolet light. The drawing apparatus forms a (latent image) pattern on the substrate (the upper resist) using, for example, a charged particle beam (electron beam or the like). The imprint apparatus forms a pattern on the substrate by molding an imprint material on the substrate.

  The method for manufacturing an article in the embodiment of the present invention is suitable for manufacturing an article such as a microdevice such as a semiconductor device or an element having a fine structure. Such a manufacturing method uses a lithography apparatus having the above-described stage apparatus 500 to form a (latent image) pattern on a substrate coated with a photosensitive agent (step of drawing on the substrate), and the pattern is formed in this step. Developing the formed substrate. Further, following the forming step, the manufacturing method may include other well-known steps (oxidation, film formation, vapor deposition, doping, planarization, etching, resist peeling, dicing, bonding, packaging, and the like). The method for manufacturing an article in the present embodiment is advantageous in at least one of the performance, quality, productivity, and production cost of the article as compared with the conventional method.

  As mentioned above, although preferable embodiment of this invention was described, it cannot be overemphasized that this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

1: Drive device 11: Ball screw 12: Nut 17: Encoder 18: Scale 19: Head

Claims (11)

A driving device that has a screw member and an engagement member that engages with the screw member, and moves an object by relative movement between the screw member and the engagement member;
An encoder for measuring the position of the object by reading the scale with the detector;
The scale device is disposed on the screw member.   The drive device according to claim 1, wherein the scale is spirally disposed on the screw member. The screw member includes a groove portion with which the engagement member contacts, and a non-groove portion along the groove portion,
The drive device according to claim 1, wherein the scale is disposed in the non-groove portion.   The drive device according to claim 1, wherein the detector is supported by the engagement member.   4. The apparatus according to claim 1, further comprising a table for the object, wherein the engagement member is provided on the table, and the detector is supported by the table. 5. The drive device described in 1.   The detector includes a plurality of detection elements arranged along a direction forming a torsion angle of the screw member with respect to a plane including the axis of the screw member, and the scale is connected to the scale via the plurality of detection elements. The drive device according to claim 1, wherein a plurality of marks included are detected.   The object is moved by a relative linear motion between the screw member and the engagement member by relative rotation between the screw member and the engagement member. 6. The drive device according to claim 1.   The drive device according to any one of claims 1 to 7, wherein the encoder includes an absolute encoder. An industrial machine for processing objects,
An industrial machine comprising the drive device according to any one of claims 1 to 8 that moves the object. A movable stage,
The drive device according to any one of claims 1 to 8, wherein the stage is moved;
A stage apparatus characterized by comprising: An industrial machine for processing an object,
An industrial machine comprising the stage device according to claim 10, wherein the object is moved while being held on a stage.

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