The present invention relates to a planar 3-DOF (degree of freedom) stage, which includes: a transitional manipulator section having parallel 2-DOF; a rotation manipulator section having rotation 1-DOF so as to carry out motion independently from the transitional manipulator section; and a stage base mounted with the transitional manipulator section and the rotation manipulator section and having a fixing section inside and a driving section outside. According to the planar 3-DOF stage, transitional motion and rotational motion are independently carried out so that it is possible to reduce motion errors and simplify control and design.

TECHNICAL FIELD

The present invention relates to an ultra-precision stage, and more particularly, to a planar 3-degree of freedom (DOF) stage which includes a rotational mechanism carrying out motion independent of a translational mechanism.

BACKGROUND ART

Generally, an ultra-precision stage is constituted by a piezoelectric actuator and flexural hinges, and is used in a wide range of applications, such as scanning probe microscopes, photographic printers, micro aligners, precision processing machines, micro assemblers, nano instruments, spectrometers, flat panel displays, semiconductor inspectors, and the like.

Particularly, various types of positioning devices constituted by a piezoelectric actuator and flexural hinges have been developed due to merits thereof, such as a high degree of transfer precision, easy design and easy machining. For example, with the development of robotics, many studies have been conducted with respect to a positioning device configured to carry out translational motion of 2 degrees of freedom and rotational motion of 1 degree of freedom.

It should be noted that the above description is provided for understanding of the background art and is not a description of a well-known technique in the art.

DISCLOSURE

Technical Problem

A conventional stage configured to carry out translational motion of 2 degrees of freedom and rotational motion of 1 degree of freedom has a parallel structure. Accordingly, in the conventional stage, an actuator for translational motion, an actuator for rotational motion, and guide units for guiding such motions are connected to one another, so that unintended motion is likely to occur together with intended motion even when one of the translational motion and the rotational motion is intended, thereby causing motion errors. In order to prevent such motion errors, the stage requires an additional control mechanism, thereby providing a more complicated structure while deteriorating the degree of precision.

Therefore, there is a need to solve such problems of the related art.

The present invention has been conceived to solve such problems of the related art and is directed to providing a planar 3-DOF stage which has a simple structure and may improve the degree of precision.

Technical Solution

In accordance with an aspect of the present invention, a planar 3-DOF stage includes: a translational mechanism carrying out translational motion of 2 degrees of freedom; a rotational mechanism carrying out rotational motion of 1 degree of freedom independent of the translational mechanism; and a stage base equipped with the translational mechanism and the rotational mechanism, and having a stationary section formed on an inner region thereof and an operating section formed on an outer region thereof.

The translational mechanism may include a cymbal mechanism disposed between the stationary section and the operating section such that the cymbal mechanism is connected at one side thereof to the stationary section and at the other side thereof to the operating section, and the rotational mechanism may include a Scott-Russell linkage disposed on the stationary section.

The translational mechanism may include a plurality of cymbal mechanisms bisymmetrically installed on the stage base. Here, each cymbal mechanism is disposed between the stationary section and the operating section such that the cymbal mechanism is connected at one side thereof to the stationary section and at the other side thereof to the operating section

The cymbal mechanisms may include a pair of first cymbal units disposed at upper and lower portions of the stage base, and a pair of second cymbal units disposed at right and left sides of the stage base.

The pair of first cymbal units and the pair of second cymbal units may be disposed orthogonal to each other, and when one of the first cymbal units is displaced, the pair of second cymbal units may guide translational motion of the operating section by the pair of first cymbal units.

The cymbal mechanism may include an inner end connected to the stationary section; an exterior end disposed at an opposite side to the interior end and connected to the operating section; a first end disposed between the operating section and the stationary section; a second end disposed at an opposite side to the first end; a first flexural hinge link connecting the first end to the exterior end; a second flexural hinge link connecting the exterior end to the second end; a third flexural hinge link connecting the second end to the interior end; and a fourth flexural hinge link connecting the interior end to the first end, and a first actuator may be interposed between the first end and the second end to change a distance between the first end and the second end.

The Scott-Russell linkage may include a first link connected to the other side of a second actuator connected at one side thereof to the stationary section; a second link connected at one side thereof to the first link and connected at the other side thereof to the stationary section such that the second link is rotated by movement of the first link to rotate the stationary section; and a third link connected at one side thereof to the second link and connected at the other side thereof to the stationary section.

The rotational mechanism may further include a leaf spring disposed outside the Scott-Russell linkage to guide rotation of the stationary section.

The rotational mechanism may include a plurality of leaf springs disposed outside the Scott-Russell linkage to guide rotation of the stationary section and arranged at equal rotational intervals about the center of the stationary section.

The translational mechanism and the rotational mechanism may be coplanar with each other on the stage base.

Advantageous Effects

According to exemplary embodiments, a planar 3-DOF stage allows translational motion and rotational motion to be independently carried out, thereby reducing motion errors while facilitating control and design thereof.

Further, the planar 3-DOF stage according to the exemplary embodiments includes a translational mechanism and a rotational mechanism arranged coplanar with each other, thereby simplifying the structure thereof while improving responsiveness with respect to inertia moment by lowering the center of motion.

BEST MODE

Exemplary embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. It should be noted that the drawings are not to precise scale and may be exaggerated in thickness of lines or size of components for descriptive convenience and clarity only.

Further, terms used herein are defined by taking functions of the present invention into account and can be changed according to the custom or intention of users or operators. Therefore, definition of the terms should be made according to the overall disclosure set forth herein.

FIG. 1is a perspective view of a planar 3-DOF stage in accordance with one exemplary embodiment;FIG. 2is a plan view of the planar 3-DOF stage in accordance with the exemplary embodiment,FIG. 3is a plan view of a translational mechanism of the planar 3-DOF stage in accordance with the exemplary embodiment;FIG. 4is a plan view of a rotational mechanism of the planar 3-DOF stage in accordance with the exemplary embodiment;FIG. 5is a plan view of a cymbal mechanism of the planar 3-DOF stage in accordance with the exemplary embodiment;FIG. 6is a plan view of the planar 3-DOF stage in accordance with the exemplary embodiment when carrying out translational motion; andFIG. 7is a plan view of the planar 3-DOF stage in accordance with the exemplary embodiment when carrying out rotational motion.

Referring toFIGS. 1 to 7, the planar 3-DOF stage1according to the embodiment of the invention includes a translational mechanism100, a rotational mechanism200, and a stage base300.

The stage base300includes a stationary section310and an operating section320. The rotational mechanism200is disposed on the stationary section310and the translational mechanism100is disposed between the stationary section310and the operating section320.

The stationary section310is formed on an inner region of the stage base300and the operating section320is formed on an outer region of the stage base300. A cymbal mechanism110is interposed between the stationary section310and the operating section320to divide the stationary section310and the operating section320.

The stationary section310is surrounded by the cymbal mechanism110and is kept in a stationary state instead of carrying out translational motion during operation of the translational mechanism100. Further, during operation of the rotational mechanism200, some region of the stationary section310rotates in the clockwise or counterclockwise direction, and the remaining region is kept in a stationary state instead of rotating. Specifically, during operation of the rotational mechanism200, an exterior portion310aof the stationary section310is rotated by a Scott-Russell linkage210described below, whereas an interior portion310bof the stationary section310is secured by a leaf spring220described below, instead of rotating.

The operating section320is disposed outside the cymbal mechanism110and is moved along one axis or along the other axis orthogonal to the one axis during operation of the translational mechanism100. Further, the operating section320is rotated in the clockwise or counterclockwise direction during operation of the rotational mechanism200.

The translational mechanism100carries out translational motion of 2 degrees of freedom. In other words, the translational mechanism100carries out translational motions in one axial direction and in another axial direction orthogonal to the one direction. Such a translational mechanism100is mechanically separate from the rotational mechanism200, so that operation of the translational mechanism100does not influence operation of the rotational mechanism200.

Similarly, operation of the rotational mechanism200does not influence operation of the translational mechanism100. As such, since the translational mechanism100and the rotational mechanism200are independently moved so as not to affect each other, it is possible to prevent motion errors caused by unintended motion.

The translational mechanism100includes the cymbal mechanism110.

The cymbal mechanism110is disposed between the stationary section310and the operating section320. The cymbal mechanism110is connected at one side thereof to the stationary section310via a flexural hinge and at the other side thereof to the operating section320via a flexural hinge. Here, since the configuration of the flexural hinge is apparent to a person having ordinary knowledge in the art, a detailed description thereof will be omitted herein.

The planar 3-DOF stage1according to the embodiment includes a plurality of cymbal mechanisms110bisymmetrically arranged on the stage base300. Although this embodiment is illustrated as including four cymbal mechanisms110symmetrically arranged at upper, lower, right and left sides of the stage base inFIG. 2, the invention is not limited thereto. That is, any number of cymbal mechanisms110may be provided so long as the cymbal mechanisms are bisymmetrically arranged on the stage base.

In this embodiment, four cymbal mechanisms are arranged at rotational intervals of 90 degrees about the center of the stage base300.

The cymbal mechanisms110are constituted by a pair of first cymbal units120disposed at upper and lower portions of the stage base300and a pair of second cymbal units130disposed at right and left sides of the stage base.

The pair of first cymbal units120is disposed orthogonal to the pair of second cymbal units130. Accordingly, when one of the first cymbal units120is displaced, the pair of second cymbal units130disposed horizontal to a moving direction of the operating section320by the pair of first cymbal units120guides translational motion of the operating section320so as to achieve stable movement of the operating section320without rattling.

That is, when the operating section320is moved downwards by operation of a first cymbal unit111disposed at an upper portion of the stage base300, the pair of second cymbal units130disposed at the right and left sides guides the operating section320so move downwards without rattling.

Similarly, when one of the second cymbal units130is displaced, the pair of first cymbal units120disposed horizontal to a moving direction of the operating section320by the pair of second cymbal units130guides translational motion of the operating section320in a lateral direction so as to achieve stable movement of the operating section320in the lateral direction without rattling.

As a result, according to the present invention, the cymbal mechanisms110may not only increase or decrease the displacement thereof, but also guide the translational motion of the operating section320.

On the other hand, as described above, during movement of the translational mechanism100, the rotational mechanism200mechanically separated from the translational mechanism100does not rotate the operating section320.

Each of the cymbal units constituting the cymbal mechanisms110includes an interior end141, an exterior end142, a first end143, a second end144, a first flexural hinge link151, a second flexural hinge link152, a third flexural hinge link153, and a fourth flexural hinge link154.

The interior end141is disposed inside the stationary section310and connected to the stationary section310via a flexural hinge, and the exterior end142is disposed at an opposite side to the interior end141and is connected to the operating section320via a flexural hinge.

Translational motion of the operating section320by operation of the cymbal mechanisms110occurs when the exterior end142is moved by displacement of the cymbal mechanisms, with the interior end141secured by the stationary section310.

The first end143is disposed between the stationary section310and the operating section320, and is coupled to one end of a first actuator410. Here, a piezoelectric actuator may be applied to the first actuator410. The piezoelectric actuator is operated based on a piezoelectric phenomenon in which application of pressure to both sides of the piezoelectric actuator results in generation of positive and negative charges proportional to the applied pressure. Specifically, when voltage is applied to both sides of the piezoelectric actuator, deformation of the piezoelectric actuator occurs such that the piezoelectric actuator is stretched in one direction and shrunk in another direction perpendicular to the one direction. Based on this phenomenon, the piezoelectric actuator is used as an actuating source for the stage for carrying out ultra precision motion.

The second end144is disposed between the stationary section310and the operating section320and is coupled to the other end of the first actuator410. The second end144is placed at an opposite side to the first end143.

The first actuator410is interposed between the first end143and the second end144. The first actuator410may be interposed between the first end143and the second end144through various coupling ways, such as press-fitting and the like.

The interior end141, the exterior end142, the first end143and the second end144are connected to one another by flexural hinge links. Specifically, a first flexural hinge link151connects the first end143and the exterior end142, a second flexural hinge link152connects the exterior end142and the second end144, a third flexural hinge link153connects the second end144and the interior end141, and a fourth flexural hinge link154connects the interior end141and the first end143.

In the cymbal unit111constituted by the interior end141, exterior end142, first end143and second end144, and the flexural hinge links connecting these components to one another, when the distance between the first end143and the second end144is increased by operation of the first actuator410, the distance between the interior end141and the exterior end142is reduced.

Here, since the interior end141is securely connected to the stationary section310, reduction in distance between the interior end141and the exterior end142is achieved mainly by movement of the exterior end142.

As the exterior end142moves, the operating section320linked to the exterior end142by the flexural hinge link is also moved. As a result, when the first actuator410operates, the operating section320performs translational motion in a moving direction of the exterior end142towards the interior end141.

The rotational mechanism200carries out rotational motion of 1 degree of freedom independent of the translational mechanism100. The rotational mechanism200includes a Scott-Russell linkage210.

The Scott-Russell linkages210includes a first link211, a second link212and a third link213, and is disposed in the interior portion310bof the stationary section310. The Scott-Russell linkage210constitutes a Scott-Russell mechanism through operation of the respective components thereof.

The first link211is connected to the other end of a second actuator420connected at one end thereof to the stationary section310. Here, as in the first actuator410, a piezoelectric actuator may be applied to the second actuator420.

The second link212is connected at one end thereof to the first link211via a flexural hinge and at the other end thereof to the exterior portion310aof the stationary section310via a flexural hinge. Accordingly, when the first link211approaches the second link212by operation of the second actuator420, the second link212is rotated in the clockwise direction about a connecting point between the second link212and the third link213.

As the second link212is rotated in the clockwise direction, the exterior portion310aof the stationary section310connected to the second link212by the flexural hinge is also rotated in the clockwise direction.

The third link213is connected at one end thereof to the second link212via a flexural hinge and at the other end thereof to the interior portion310bof the stationary section310via a flexural hinge. Thus, when the second link212rotates in the clockwise direction, the third link213rotates in the counterclockwise direction about the connecting point between the second link212and the third link213.

The rotational mechanism200may further include leaf springs220. The leaf springs220are disposed outside the Scott-Russell linkage210on the stationary section310and guide rotation of the stationary section310by operation of the second actuator420.

Specifically, plural leaf springs220are arranged at equal rotational intervals about the center of the stationary section310such that, during rotation of the exterior portion310aof the stationary section310, the interior portion310bof the stationary section310is kept in a stationary state instead of rotating. As a result, the interior portion310bof the stationary section310guides rotation of the exterior portion310aof the stationary section310and the operating section320.

Although this embodiment is illustrated as including four leaf springs220arranged at rotational intervals of 90 degrees about the center of the stationary section310, the present invention is not limited thereto. For example, the rotational mechanism may include two leaf springs arranged at rotational intervals of 180 degrees or three leaf springs arranged at rotational intervals of 120 degrees, without being limited thereto.

As such, the translational mechanism100and the rotational mechanism200are disposed coplanar with each other on the stage base300to lower the center of motion, thereby improving responsiveness with respect to moment of inertia.

Next, operation of the planar 3-DOF stage according to the exemplary embodiment of the invention will be described with reference to the drawings.

First, the translational motion of the planar 3-DOF stage1will be described.

When voltage is applied to the first actuator410of the upper cymbal unit111in the pair of first cymbal units120, the first actuator410is stretched in opposite directions and compresses the first and second ends143,144, which are coupled to the first actuator410, so that the first end143is moved to the left and the second end144is moved to the right, thereby increasing the distance between the first end143and the second end144.

As a result, the distance between the interior end141and the exterior end142connected to the first end143and the second end144via the flexural hinge links decreases. Here, since the interior end141is secured to the stationary section310, reduction in distance between the interior end141and the exterior end142is achieved mainly by movement of the exterior end142

As the exterior end142moves, the operating section320linked to the exterior end142by the flexural hinge link is also moved by the moving distance of the exterior end142towards the interior end141. Since such movement of the operating section320is guided by the pair of second cymbal units130disposed horizontal to the moving direction of the operating section320, translational motion of the operating section320may be stably carried out without rattling.

Next, the rotational motion of the planar 3-DOF stage1will be described.

When voltage is applied to the second actuator420of the rotational mechanism200, the second actuator420is stretched in opposite directions. Here, since the second actuator420is secured at one end thereof to the stationary section310, the second actuator420is stretched only in a direction towards the other end thereof. As the second actuator420is stretched, the first link211compresses the second link212while moving towards the second link212.

As a result, the second link212is rotated in the clockwise direction about the connecting point between the second link212and the third link213, and the exterior portion310aof the stationary section310connected to the second link212via the flexural hinge is also rotated in the clockwise direction. Here, since the leaf springs220are arranged outside the Scott-Russell linkage210to guide rotation of the exterior portion310a, the interior portion310bof the stationary section310is kept in a stationary state while guiding rotation of the exterior portion310a.

As such, since the interior portion310bis kept in a stationary state by the Scott-Russell linkage210and the leaf springs220and the exterior portion310ais rotated in the clockwise direction, the operating section320connected to the exterior portion310amay also carry out rotational motion in the clockwise direction.

Although some embodiments have been described herein, it should be understood by those skilled in the art that these embodiments are given by way of illustration only, and that various modifications, variations, and alterations can be made without departing from the spirit and scope of the invention. Therefore, the scope of the invention should be limited only by the accompanying claims and equivalents thereof.