JPS63274894A - Feeder - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a feeding device, and more particularly to a device for feeding a movable element along a fixed table.

[Summary of the invention]

The present invention combines minute shearing deformation of a piezoelectric material or the like with an expansion/contraction mechanism to repeat minute feeding, thereby enabling long-distance linear feeding and minute feeding in the circumferential direction. It is designed to be applicable to stage feed and stepping motors of scanning tunneling microscopes. K. Prior Art In a conventional linear feed mechanism, a stage guided by some linear guide means is fed using a drive motor and a feed screw. Alternatively, a method of sending using an electromagnetic linear motor has been considered. Furthermore, when a piezoelectric body is used for precise positioning, expansion and contraction of the piezoelectric body or bending deformation of a bimorph plate is utilized. K Problems to be Solved by the Invention] Feeding devices using feed screws or electromagnetic linear motors have low accuracy and are unsuitable for minute feeding. When the deformation of the piezoelectric body is utilized, the accuracy of feeding increases, but a sufficient amount of deformation cannot be obtained. Even if some kind of displacement magnification mechanism is used, the equation 1
Only a stroke of 0 μm can be obtained. Inch worm is a precision feed for obtaining many strokes. The inch worm connects two stages that can be attracted to a fixed base using a piezoelectric material that expands and deforms, and in one step, one stage is attracted to extend the piezoelectric material, and then the other stage is attracted to and contracted. By repeating this, the inchworm moves and is sent. Although such a device can have a sufficiently long stroke, it has the disadvantage of slow operation time because it uses electrostatic adsorption. Since the suction and expansion/contraction are repeated roughly, there is a drawback that imaging occurs in a direction perpendicular to the direction of movement, that is, in the suction direction. The present invention was made in view of these problems, and an object of the present invention is to provide a feeding device that is capable of fine feeding with high precision, provides a sufficient stroke, and has excellent responsiveness. That is.

[Means to solve the problem]

The present invention provides an apparatus for transporting a movable element along a fixed base, in which drive legs that shear deform in the direction of movement of the movable element are provided on the movable element or the fixed base, and the driving legs are connected to the fixed base or the fixed base. A means for freeing the movable element is provided, and the drive leg is sheared and deformed by frictional force or engagement force so as not to slip relative to the fixed base or the movable element, and then the freeing means causes the driving leg The leg is made free with respect to the fixed base or the movable element, and in this state, the driving leg is sheared in the opposite direction to the deformation, and this operation is repeated and the movable element is moved to the fixed base. According to the present invention, the drive leg is made of a deformable material such as a piezoelectric element or a magnetostrictive element, and the drive leg is made of a deformable material such as a piezoelectric element or a magnetostrictive element. It is now possible to feed the mover using shear deformation in combination with a freeing means, and even though it is a very small amount for one step, by repeating this, a sufficient stroke can be achieved. It becomes possible to do so. K Embodiment A first embodiment will be described with reference to FIGS. 1 to 4. In this embodiment, the present invention is applied to a feeding device for a movable stage 10 of a scanning tunneling microscope, and as shown in FIGS. 2 and 3, the movable stage 10 has four It is adapted to be fed on the base 13 in the X- and Y-axis directions by respective drive legs 11, 12. Also, a magnet 22 is placed on the underside of the stage 10.
is fixed to the drive leg 11.12 so that the suction force acting on the iron base 13 generates sufficient frictional force on the drive leg 11.12. A frame 14 is mounted upright on the movable stage 10, and a holder 15 is supported by the frame 14 via a spring 16. Between the holder 15 and the frame 14, there are four
A book drive leg 17 is provided and is fixed to the holder 15 side. The driving leg 17 is designed to generate sufficient frictional force against the frame 14 by the spring 16. Further, the holder 15 holds the probe 19 via a precision feeder 18. The probe 19 measures the shape of the surface of the sample 21 on the sample stage 20 by passing a tunnel current through it. Next, the structure of the drive leg will be explained. As shown in FIG. 4, the driving leg 11 is a stack of two piezoelectric bodies 25 and 26, and the upper piezoelectric body 25 is polarized in the thickness direction so as to be deformed in the direction of expansion and contraction. In contrast, the lower piezoelectric body 26 is laterally polarized so as to undergo shear deformation. Note that the direction of polarization is indicated by arrows in FIG. Further, the piezoelectric bodies 25 and 26 may have either a single structure or a laminated structure depending on the purpose. A voltage is applied by three electrodes 27, 28, and 29 to cause expansion/contraction or shear deformation. The middle common electrode 28 is grounded and the voltage ve is applied to the electrode 27.
When is applied, the piezoelectric body 25 expands and contracts in the direction of the electric field. On the other hand, when a voltage of Vs is applied to the electrode 29, the piezoelectric body 26 undergoes shearing deformation perpendicular to the direction of the electric field. This shear deformation is reversed by the polarity of the voltage applied to the voltage 1M29. The operation of moving the movable stage 10 in the X-axis direction using a pair of such X-axis drive tl[11 will be explained with reference to FIG. This motion is basically similar to that of a human walking. When the device is stationary, the driving legs 11 in the X-axis direction and the driving legs 12 in the Y-axis direction are both in contact with the base 13, as shown in FIG. 1A. In this state, as shown in FIG. 1B, the drive leg 12 in the Y-axis direction is lengthened by extending the piezoelectric body 25, and the drive leg 11 in the X-axis direction is shortened by contracting the piezoelectric body 25. That is, here, when moving the stage 10 in the X-axis direction, the driving legs 12 in the Y-axis direction are used as supporting legs or floating means. The lower piezoelectric body 26 of the floating driving leg 11 in the X-axis direction is sheared and deformed in the plane direction of the base 13 and in the moving direction of the stage 10, that is, to the left in FIG. 1C. Next, the piezoelectric body 25 is expanded to lengthen the drive leg 11 in the X-axis direction, and the piezoelectric body 25 of the drive leg 12 is contracted to shorten the drive leg 12. As a result, the drive leg 11 in the X-axis direction comes into contact with the base 13, as shown in the first diagram. Sufficient frictional force is obtained between the lower surface of the drive leg 11 and the base 13 due to the attraction force of the magnet 22. In this state, as shown in FIG. 1E, the piezoelectric body 26 of the drive leg 11 is sheared and deformed in the -X direction, that is, in the right direction. At this time, the stage 10 moves by a distance equal to the amount of shearing deformation of the piezoelectric body 26. Next, the piezoelectric body 25 of the drive leg 11 in the X-axis direction is contracted to shorten its length and move away from the base 13. At the same time, the piezoelectric body 25 of the drive leg 12 in the Y-axis direction is extended to increase its length, and the drive leg 12 is used as a support leg to support the base 1.
Supports 0. With the driving leg 11 floating in the X-axis direction in this manner, the piezoelectric body 26 of the driving leg 11 is again sheared in the feeding direction as shown in FIG. 1C. By repeating the same operation, it becomes possible to move the movable stage 10 to the left in FIG. 1. Therefore, as long as the base 13 continues, the movable stage 10 can be moved infinitely. In the case of one-step feeding, the driving leg 11 may be straightened by setting the shearing deformation of the piezoelectric body 26 in FIG. 1C as a neutral position. Also, to reverse the direction, drive 1!11
This is achieved by reversing the polarity of the voltage applied to the piezoelectric body 26 to change the direction of shear deformation when the piezoelectric body 11 is contracted and expanded. In the operation shown in FIG. 1, the driving leg 12 in the Y-axis direction is used as a supporting leg or a floating means to perform linear feeding, but the driving leg 12 is also deformed in the same direction as the driving leg 11. Then, i.e. drive l1111 and drive 1
By making the legs 1112 alternately function as driving legs and supporting legs, the stage 10 moves twice as fast in the X-axis direction. Further, by deforming the drive leg 11 in the X-axis direction in the Y-axis direction, an X-Y stage that can also be moved in the Y-axis direction can be obtained. Further, when the stage 10 is sent only in the X-axis direction, the drive leg 12 may be composed only of the piezoelectric body 25 that expands and contracts, and the drive leg 11 in the X-axis direction may be composed only of the piezoelectric body 26 that shears and deforms. . Alternatively, it is also possible to make the support leg 12 a constant length and to bring the drive leg 11 into contact with or away from the base 13 using the piezoelectric body 25 of the drive leg 11. The stage 10 of the scanning tunneling microscope shown in FIGS. 2 and 3 is moved in the X-axis direction by drive legs 11,
It is adapted to be moved in the Y-axis direction by drive legs 12. And the amount of movement per step in both directions is 0.6μm
This allows the probe 19 to move coarsely in the X-axis direction and the Y-axis direction. Further, movement in the Z-axis direction is achieved by moving the holder 15 along the vertical plane of the frame 14 using the driving legs 17. The spring 16 connects the lower surface of the driving leg 17 to the frame 1.
40 surface, vertical movement in the Z-axis direction or vertical direction is possible without slipping due to gravity. The probe 19 is further precisely fed in the X, Y, and Z axis directions by the precision feeder 18, and thereby positioned in the Z axis direction at each scanning position so that the tunnel current is constant. The shape of the surface of the sample 21 is observed from the information. Next, a second embodiment will be explained with reference to FIGS. 5 to 7. In this embodiment, the present invention is applied to a stepping motor in which the feed port per step is minute. The motor includes a casing 33, by which an output shaft 36 is rotatably supported via a pair of bearings 34,35. A rotor 37 is fixed to the output shaft 36 and faces a stator 38 within the casing 33. As shown in FIG. 6, the stator 38 receives a stopper 39 on the casing 33 side in a recess 40, thereby preventing rotation. Twelve driving legs 51, 52, 53 are mounted on the stator 38 at 30 degree intervals and are pressed toward the rotor 37 by a compression coil spring 41. The drive legs 51, 52, and 53 constitute drive means for A, B, and C phases, and the phases are 12 as shown in FIG.
Voltages shifted by 0 degrees are applied, so that the timing at which the piezoelectric body 26 on the tip side undergoes shearing deformation is shifted by 120 degrees. That is, according to this stepping motor, the drive legs 51, 52, and 53 rotate the rotor 37 in the tangential direction while sequentially functioning as drive legs, thereby extracting rotational force from the output shaft 36. Moreover, as shown in FIG. 7, the voltages of each phase overlap slightly, thereby enabling smooth rotation when switching the torques of the three drives g51 to g53. In such a stepping motor, the rotation angle per step will be determined. If the rotation angle is 6 degrees per step in the circumferential direction of a circle with radius r, then the rotation angle is Δθ=(Δfl/2πr)・2π・(360/2π)−
(180/π)・(Δb/') degree. Therefore, for example, if Δβ-0.5 μs and r-1■, the angle becomes a minute angle of ΔθΦ0.0031. Also, the time required for one step is 10-6 It is now possible to shorten the time to about seconds, and the rotation speed at this time is (0,003/360) x 10'+8 (7 seconds of rotation)
Therefore, a stepping motor that rotates at this rotational speed can be obtained. In the above embodiment, the driving legs 51 to 53 are pressed to the upper surface of the rotor 37 and rotated, but the driving legs 51 to 53 can be pressed to the outer peripheral surface of the rotor 37 and sheared. Alternatively, the rotational force may be extracted. In this case, it becomes possible to make the motor thinner. Effects of the Invention 1 As described above, the present invention causes the drive leg to be sheared and deformed by frictional force or engagement force to prevent it from slipping relative to the fixed base or the movable element, and then shearly deforms the drive leg relative to the fixed base or the movable element. In this state, the drive leg is sheared in the opposite direction to the deformation described above, and by repeating this operation, the mover is sent in the direction of the shearing deformation relative to the fixed base. Therefore, by utilizing the shearing deformation of the piezoelectric element or magnetostrictive element, highly accurate minute feeding can be achieved, and by repeating this operation, infinite feeding is possible as long as the fixed table continues.

[Brief explanation of the drawing]

FIG. 1 shows the X of the movable stage according to the first embodiment of the present invention.
FIG. 2 is a front view showing the feeding operation in the axial direction, FIG. 2 is a plan view of the main part showing the feeding mechanism of the movable stage, FIG.
The figure is an external perspective view of the drive leg, FIG. 5 is a vertical sectional view of the stepping motor according to the second embodiment, FIG. 6 is a sectional view taken along the line ■ to ■ in FIG. 5, and FIG. 7 is a voltage applied to the drive leg. FIG. In addition, in the symbols used in the drawings, 10...Movable stage 11...Drive leg (X-axis direction) 12...
・・・・・・Drive leg (Y-axis direction) 13・・・・・・・・・Base 25・・・・・・Piezoelectric body (expanding and contracting) 26・・・・・・Piezoelectric body (shearing deformation) 27.28.
29... Electrode. Figure 1 J/l -Kakeka4~-''

Claims (1)

[Claims] In a device for transporting a movable element along a fixed base, driving legs that shear deform in the moving direction of the movable element are provided on the movable element or the fixed base, and the driving legs are attached to the fixed base or the movable element. providing a means for freeing the drive leg by frictional force or engagement force to shear and deform the drive leg so that it does not slip with respect to the fixed base or the movable element;
Next, the driving leg is made free with respect to the fixed base or the movable element by the freeing means, and in this state, the driving leg is sheared in a direction opposite to the deformation, and this operation is repeated thereafter. A feeding device characterized in that the mover is fed in the direction of the shearing deformation with respect to the fixed base.