JP4636660B2 - Linear positioning device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a linear positioning device that performs linear positioning at high speed and high accuracy.
[0002]
[Prior art]
As linear positioning means, those using a ball screw drive or a linear motor are widely known. However, in these conventional techniques, the positioning accuracy is at most ± 0. The limit was about several μm. On the other hand, in the case of positioning means using a fine actuator such as a piezoelectric type, although high accuracy of about ± 0.0 μm is obtained, it is not suitable for long distance positioning. Accordingly, the linear motor is used as the coarse movement positioning means, and fine movement positioning means including a fine movement actuator such as a piezoelectric type is mounted on the movable element, and a combination of the coarse movement positioning means and the fine movement positioning means is combined. A dynamic linear positioning device is also considered.
[0003]
By the way, the conventional double-acting linear positioning device in which the fine-motion positioning means comprising a fine-motion actuator such as a piezoelectric type is mounted on the mover of the linear motor is restricted by the movement range of the fine-motion actuator. When exceeding, coarse movement by movement of the mover of the linear motor was necessary. Therefore, each time, drive control of the linear motor is involved, which is troublesome and difficult to increase the speed, and processing for absorbing the position change of the mover of the linear motor at that time is also necessary. In addition, the minimum travel distance of the coarse movement is also limited by the minimum feed amount of the linear motor, that is, the positioning accuracy of the mover. As a result, the minimum feed amount of the linear motor is about the same as the movement range of the fine actuator. If not configured, the positioning resolution as a whole is lowered, so that a highly accurate and more expensive linear motor is required.
[0004]
[Problems to be solved by the invention]
The present invention has been developed in view of the above-described conventional technical circumstances, and eliminates the restriction due to the movement range of the conventional fine movement actuator, and allows fine movement without coarse movement as a mover of the linear motor. It is an object of the present invention to provide an easy-to-use linear positioning device capable of finely adjusting the position of the movable element over a wide range by repeating fine movement by an actuator.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention is provided with a coarse feed means comprising a linear motor provided with a mover movably with respect to a stator, and a fine actuator provided with an inertial body with respect to the mover. Further, a technical means is provided that includes a fine movement feeding means for moving the mover slightly by a reaction of the inertial body when the inertial body is actuated by the fine movement actuator, and a braking means capable of braking the mover. Further, the braking means includes a fixed braking wall made of a magnetic material disposed along the stator and a braking pad having a magnetostrictive element installed on the mover side as main elements, The technical means is adopted in which the braking pad is pressed against the fixed braking wall and braked by the deformation of the magnetostrictive element caused by the change. When the mover is moved slightly, the inertial body is operated in a braking state in which the brake pad is pressed against the fixed braking wall, so that the reaction of the inertial body overcomes the braking action and the movable body is moved. The child is moved slightly. According to the present invention, by utilizing the reaction added to the mover by the kinetic energy of the inertial body during the operation of the fine actuator, the mover itself is obtained from the relative relationship with the braking action by the braking means. It is possible to position by slightly moving. Therefore, it is freed from the restrictions due to the movement range of the conventional fine actuator. Further, the brake can be configured to be braked by pressing the brake pad against the fixed brake wall by utilizing a deformation that expands or contracts by a magnetic field applied to the magnetostrictive element. Incidentally, when using a magnetostrictive element that deforms and contracts when a magnetic field is applied, the magnetostrictive element contracts and deforms when the magnetic field is applied, separating the braking pad from the fixed braking wall, and stopping the application of the magnetic field to the original length. It can be configured to exhibit a braking action when it is restored. As the fine actuator, an electrostrictive element or a magnetostrictive element is suitable.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The present invention can be widely applied as linear positioning means for performing linear positioning at high speed and with high accuracy. For example, it is suitable as a positioning means in a semiconductor manufacturing apparatus such as a bonder or a stepper. A fine movement actuator composed of a magnetostrictive element, an electrostrictive element or the like is installed on the mover constituting the linear motor, and an inertial body is provided at the end of the fine movement actuator. The size of the inertial body is appropriately set so as to obtain a reaction suitable for securing the desired minute movement based on the relationship between the mass of the mover and the braking action. On the other hand, the braking means disposed on the mover is configured so as to obtain a braking action suitable for securing an intended minute movement from the relationship with the reaction from the inertial body acting on the mover. Incidentally, whether or not the mover itself causes a slight movement depending on whether the reaction acting on the mover within the range of static friction of the braking means according to the operating speed of the fine actuator or the dynamic friction beyond the static friction is reached. Will be affected. Furthermore, it is also possible to configure so that the minute moving distance of the mover can be adjusted by finely adjusting the braking force.
[0007]
When a magnetostrictive element is used as the fine movement actuator, it expands and contracts in the direction of the applied magnetic field, and the expansion / contraction amount is large. For example, it can be expanded and contracted by a length of 200 mm by 140 μm. When an electrostrictive element is used, the electrostrictive element expands and contracts in the voltage direction, and the operation speed is faster than that of the magnetostrictive element, but the expansion / contraction amount is as small as about 1 μm. Therefore, the magnetostrictive element is more suitable as the actuator for the braking means. Further, when a magnetostrictive element is used as means for operating the braking means disposed on the mover, there are a form using a magnetostrictive element that expands by applying a magnetic field and a form using a magnetostrictive element that reduces by applying a magnetic field. obtain. In the case of the former form, it is set so that the braking pad is separated from the fixed braking wall without applying a magnetic field, and the braking pad is pressed against the fixed braking wall and exerts a braking action at the time of expansion deformation due to application of the magnetic field. On the other hand, in the case of the latter form, the braking pad is separated from the fixed braking wall in a state where a magnetic field is applied, and the braking pad is pressed against the fixed braking wall when returning to the original length by stopping the application of the magnetic field. And set so as to exert a braking action.
[0008]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing the main part of one embodiment of the present invention. 2 to 4 are enlarged sectional views of FIG. 1, FIG. 2 is an AA sectional view, FIG. 3 is a BB sectional view, and FIG. 4 is a CC sectional view. In the figure, reference numeral 1 denotes a stator, which is configured such that, for example, a moving magnetic field is formed so that the movable element 2 can be moved to a predetermined position, and a linear motor is constituted by using the stator 1 and the movable element 2 as main elements. is doing. As shown in FIGS. 2 and 3, the stator 1 is installed in the recess of the guide rail 3, and the mover 2 is configured to engage with the guide rail 3 and move from the outside. ing. The guide rail 3 is further installed in a concave portion of a U-shaped frame 4 made of a magnetic material, and rising walls of the U-shaped frame 4 are configured as fixed braking walls 5 and 6.
[0009]
As shown in the figure, in this embodiment, a fine movement actuator 7 made of a magnetostrictive element is installed on the mover 2, and an inertia body 8 is provided at the other end of the fine movement actuator 7. A solenoid coil 12 having an iron core 11 is installed on the opposite side of the mover 2 through holding members 9 and 10 made of a non-magnetic material so as to block the influence of magnetism. 12 can be braked by applying a magnetic field to the portions of the brake pads 13 and 14 using the magnetostrictive elements by extending the current, and pressing the brake pads 13 and 14 against the fixed brake walls 5 and 6. It is configured as follows. Incidentally, as shown in FIG. 4, when the solenoid coil 12 is turned on to start excitation, a magnetic circuit M is formed by the iron core 11 and the U-shaped frame 4 provided with the fixed braking walls 5 and 6. A magnetic field is applied to the brake pads 13 and 14.
[0010]
Next, the operation of the linear positioning device according to the present invention will be described. In order to send the mover 2 to the target position, first, similarly to the case of the conventional linear motor, for example, a predetermined moving magnetic field is formed on the stator 1 by the adopted linear motor driving method, and the mover 2 is targeted. Coarse feed to near the position. In this case, as position recognition means, a high-precision measuring instrument such as a resolver provided in the movable element 2, a linear scale provided outside, or a laser length measuring instrument is used. Next, the solenoid coil 12 is energized to start excitation, and the magnetic circuit M is formed on the U-shaped frame 4 having the iron core 11 and the fixed braking walls 5 and 6. As a result, a magnetic field is applied to the portions of the brake pads 13 and 14, and as a result, the magnetostrictive elements incorporated in the brake pads 13 and 14 expand, and the brake pads 13 and 14 come into pressure contact with the fixed brake walls 5 and 6. And exerts a braking action. In addition, with the above braking operation, the drive of the mover 2 is turned off, and the next fine movement feeding operation is started.
[0011]
In the fine movement feeding operation of the movable element 2, an inertia that is installed with respect to the movable element 2 and drives the fine movement actuator 7 composed of a magnetostrictive element in the present embodiment and operates along with the operation of the fine movement actuator 7. The mover 2 is slightly moved by the reaction of the body 8. That is, the reaction to the mover 2 generated when the inertial body 8 is actuated by the fine actuator 7 is set so as to overcome the braking action caused by the pressure contact between the braking pads 13 and 14 and the fixed braking walls 5 and 6. Thus, the mover 2 can be moved slightly in the nanometer order. Accordingly, by repeating intermittent driving of the fine actuator 7, the mover 2 can be slightly moved sequentially to the target position at a nanometer pitch. Note that the braking force may be increased by increasing the current so that the mover moved to the target position does not move due to an external force.
[0012]
FIG. 5 is a schematic operation explanatory view illustrating the fine movement feeding operation of the mover 2 by the fine movement actuator 7. In addition, in this figure, the displacement amount was expanded and shown from the convenience of explanation. State A shows a state in which the mover 2 is coarsely fed to the vicinity of the target position by driving the linear motor. When the fine movement actuator 7 is rapidly extended from the state A as shown in the state B, the inertial body 8 is rapidly operated in the direction of the arrow as the fine movement actuator 7 is extended. Slightly moves in the opposite direction as shown by the arrow. That is, in the rapid extension operation of the fine actuator 7, the reaction by the inertial body 8 is also large, and the mover 2 overcomes the static friction force on the braking surface between the braking pads 13 and 14 and the fixed braking walls 5 and 6. It will move slightly in the direction of the arrow. The amount of fine movement in this case is determined by the relative relationship between the magnitude of the reaction from the inertial body 8 based on the acceleration of the fine movement actuator 7 and the braking action caused by the pressure contact between the braking pads 13 and 14 and the fixed braking walls 5 and 6. . Next, as shown in state C, the fine movement actuator 7 is slowly returned to state D similar to state A while being reduced in the direction of the arrow. In this return operation, the magnitude of the reaction by the inertial body 8 is suppressed by performing a slow reduction operation so that the static friction force on the braking surface between the braking pads 13 and 14 and the fixed braking walls 5 and 6 is not exceeded. To do. Therefore, in this return operation, the mover 2 is stopped and does not move.
[0013]
The fine movement operation in one cycle of the fine movement feeding means is completed by the rapid extension operation and the slow reduction operation of the fine movement actuator 7 in the state A to the state D described above. Then, as shown in state B, the mover 2 can be slightly moved in the direction of the arrow with a pitch P of nanometer order by the fine movement operation of one cycle. Therefore, it is possible to accurately move the mover 2 to the target position by intermittently repeating the above-described fine movement feeding means for the required number of times. In addition, if the operation pattern of the fine actuator 7 is changed so that the reduction operation is performed rapidly and the extension operation is performed slowly, the direction of the minute movement of the mover 2 can be reversed. That is, the contraction operation in the state C is performed rapidly, the movable body 2 is slightly moved in the reverse direction by the reaction of the inertial body 8 accompanying the contraction operation, and the expansion operation in the state B is performed slowly, so that the inertial body 8 If the stop force is set so as not to exceed the static frictional force on the braking surface between the braking pads 13 and 14 and the fixed braking walls 5 and 6, It is possible to reverse the direction.
[0014]
Further, in the returning operation from the state C to the state D described above, the speed of the reduction operation of the fine movement actuator 7 is set so that the magnitude of the reaction force by the inertial body 8 is the braking between the braking pads 13 and 14 and the fixed braking walls 5 and 6. If it raises once so that the static frictional force on the surface is not exceeded, and then it is set to suddenly stop at the return position of state D, the reaction of the inertial body 8 to the mover 2 at the time of the sudden stop is utilized. It is also possible to increase the pitch P in one cycle of fine movement. Similarly, an operation pattern in which the fine movement operation is repeated by shifting to the rapid extension operation of the state B from the middle of the return operation from the state C to the state D is also possible.
[0015]
【The invention's effect】
According to the present invention, since the mover itself constituting the linear motor is slightly moved based on the reaction during the operation of the inertial body provided in the fine movement actuator such as a magnetostrictive element or electrostrictive element, the fine movement actuator By repeating the above operation, it is possible to arbitrarily continue the slight movement of the mover itself. Therefore, it is possible to provide an easy-to-use linear positioning device that is free from the restriction due to the movement range of the fine actuator according to the conventional method and has good workability.
[Brief description of the drawings]
FIG. 1 is a plan view showing a main part of an embodiment of the present invention.
2 is an enlarged cross-sectional view taken along the line AA in FIG.
FIG. 3 is an enlarged cross-sectional view taken along the line BB of FIG.
4 is an enlarged cross-sectional view taken along the line CC of FIG.
FIG. 5 is a schematic operation explanatory view illustrating a fine movement feeding operation of a mover by a fine movement actuator.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Stator, 2 ... Movable element, 3 ... Guide rail, 4 ... U-shaped frame, 5, 6 ... Fixed brake wall, 7 ... Fine movement actuator, 8 ... Inertial body, 9, 10 ... Holding member, 11 ... Iron core , 12 ... Solenoid coil, 13, 14 ... Braking pad

Claims (2)

Coarse motion feed means composed of a linear motor provided with a mover movably with respect to the stator, and a fine actuator provided with an inertial body with respect to the mover, when the inertial body is operated by the fine motion actuator A fine movement feeding means for slightly moving the movable element by the reaction of the above, and a braking means capable of braking the movable element,
The braking means is composed mainly of a fixed braking wall made of a magnetic material disposed along the stator and a braking pad having a magnetostrictive element installed on the mover side, and changes the magnetic field. Due to the deformation of the magnetostrictive element that occurs, the brake pad is pressed against the fixed braking wall for braking, and when the mover is moved slightly, the braking pad is pressed against the fixed braking wall. A linear positioning device characterized in that, by operating the inertial body in a state, the reaction of the inertial body overcomes the braking action to slightly move the mover .   The linear positioning device according to claim 1, wherein an electrostrictive element or a magnetostrictive element is used as the fine movement actuator.

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