Electrical generator or motor structure – Dynamoelectric – Linear
Reexamination Certificate
2002-03-28
2004-01-13
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Linear
C355S053000, C074S4710XY, C074S490100, C074S479010, C074S479010
Reexamination Certificate
active
06677691
ABSTRACT:
This application claims priority to Japanese Patent Application No. 2001-101748 filed on Mar. 30, 2001, the disclosure of which is incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a stage apparatus for performing a predetermined work while positioning a workpiece, etc. in a two-dimensional plane in a machining apparatus or a metering device, and also relates to a method of using the stage apparatus.
2. Description of Related Art
In this kind of apparatus, as shown in
FIG. 9
, generally, a pair of parallel guide rails
201
A and
201
B extending in a Y-axis-direction within a two-dimensional plane are provided on a base
200
made of a rigid member such as a metal plate. A lower table
202
slidably supported by the guide rails
201
A and
201
B is connected to a straight drive apparatus (not shown) fixed to the base
200
. Furthermore, on the lower table
202
, a pair of parallel guide rails
203
A and
203
B extending in an X-axis-direction within a two-dimensional plane are provided. An upper table
204
slidably supported by these guide rails
203
A and
203
B is connected to a straight drive apparatus (not shown) fixed to the lower table
202
. Thereby, a workpiece laid on the upper table
204
can be positioned in the X and the Y-axis-directions.
In the aforementioned conventional stage apparatus, two tables
202
and
204
driven individually is disposed one on the other on the base
200
. Accordingly, too much load will be applied to the base
200
and/or the lower table
202
, and it is hard to equalize the dynamic characteristics of the upper and lower table
204
and
202
. Furthermore, since the table load transfer path from the upper table
204
to the base
200
is relatively long, flexure and/or deformation tends to occur in a guide member.
Especially, since each guide rail
201
A,
201
B,
203
A and
203
B has assembly accuracy limitations, it is difficult to obtain high-precision straight moving characteristics and/or rectangular guiding characteristics of the upper and lower tables. Therefore, the fluctuation of the lower table
202
causes a slight inclination of the upper table
204
toward a predetermined axial-direction as shown by the dot-dash line. In other words, since the origin of the coordinate system of the upper table
204
is slightly displaced, an error may be easily produced at the time of positioning a workpiece to a predetermined coordinate position because the axis which defines the coordinates of the upper table
204
is displaced in accordance with the movement of the lower table
202
, i.e., the so-called Abbe error is produced.
The Abbe error will be explained with reference to FIG.
10
.
The lower table
202
moves by a desired distance Y in a Ys-axis-direction while being guided by the guide rails
201
A and
201
B on the base
200
. However, if the guide rails
201
A and
201
B do not have high-precision linearity, a minute rotation displacement will be generated as shown by the dot-dash line in FIG.
10
. On the other hand, the upper table
204
is guided by both the guide rails
203
A and
203
B fixed to the lower table
202
, and moves by only the desired distance X in the Xs-axis-direction. In this case, a minute rotation displacement will be also generated.
Accordingly, when the measuring probe is disposed on the origin
0
, the measuring probe originally measures the position (−X, −Y) of the table coordinate system Os-Xs-Ys. However, if the aforementioned minute rotation is generated, the measuring probe measures the position shifted by &Dgr;X, &Dgr;Y from the position (−X, −Y). In the case where the axis of the coordinate system for measuring the amount of movement of the upper and lower tables
204
and
202
does not coincide with the position of the measuring probe, it is said “there is an Abbe error.”
On the other hand, apart from the aforementioned stage apparatus, for example, the following conventional stage apparatus as shown in
FIG. 11
is known. In the apparatus, only one table
301
is supported on a base
300
via a noncontacting bearing (not shown). The table
301
is movable in two axis directions by guide bars
302
and
303
crossing at right angles on the base
300
. Furthermore, laser interferometers
306
and
307
are provided at the positions which coincide with absolute-coordinate axes, respectively. Furthermore, bar mirrors
304
and
305
crossing at right angles are disposed on the table
301
, while an X-axis-direction linear motor
308
a
and a Y-axis-direction linear motor
308
b
are provided on the base
300
. The laser interferometer
306
and
307
observe the coordinate system and the measured value is fed back to a laser control system, so that the positioning is performed by the motors
308
a
and
308
b.
However, in this sage apparatus, a pair of driving portions are required for each axis, the X-axis and the Y-axis, and therefore the structure becomes complicated. Furthermore, it is very expensive because of the noncontacting bearing, the laser interferometers
306
and
307
, etc. Accordingly, such an apparatus cannot be introduced easily.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a stage apparatus in which deflection, deformation, etc. of a member is suppressed because of the comparatively simple structure and dynamic characteristics in both axis-directions, X-axis-direction and Y-axis-direction, are equalized.
It is another object of the present invention to provide a stage apparatus which can secure high positioning accuracy without being influenced by the so-called Abbe error.
It is still another object of the present invention to provide a method of using the aforementioned stage apparatus.
According to the first aspect of the present invention, a stage apparatus, comprises:
a table disposed above the base so as to oppose to the base;
an X-axis-direction table support mechanism portion disposed between the base and the table for supporting the table in a state that the table is capable of moving in an X-axis-direction within a two-dimensional plane;
a Y-axis-direction table support mechanism portion disposed between the base and the table for supporting the table in a state that the table is capable of moving in a Y-axis-direction within a two-dimensional plane;
an X-axis-direction linear guide portion formed on an upper surface of the base and extending in the X-axis-direction;
a Y-axis-direction linear guide portion formed on the upper surface of the base and extending in the Y-axis-direction;
an X-axis-direction movable member provided so as to move along the X-axis-direction linear guide portion and connected to the Y-axis-direction table support mechanism portion;
a Y-axis-direction movable member provided so as to move along the Y-axis-direction linear guide portion and connected to the X-axis-direction table support mechanism portion;
an X-axis-direction straight drive mechanism fixed to the base for driving the X-axis-direction movable member; and
a Y-axis-direction straight drive mechanism fixed to the base for driving the Y-axis-direction movable member,
wherein the X-axis-direction linear guide portion and the Y-axis-direction linear guide portion are arranged in a rectangular cross positional relation forming a roughly “+” shape.
In this stage apparatus, by driving the X-axis-direction movable member with the X-axis-direction straight drive mechanism, this X-axis-direction movable member is displaced in the X-axis-direction along the X-axis-direction linear guide portion on the upper surface of the base. Thereby, the table moves in the X-axis-direction via the Y-axis-direction table support mechanism portion connected to and supported by the movable member. On the other hand, by driving the Y-axis-direction movable member with the Y-axis-direction straight drive mechanism, this Y-axis-direction movable member moves in the Y-axis-direction along the Y-axis-direction linear guide portion. The table moves to the Y-axis-direction vi
Jones Judson H.
McDermott & Will & Emery
Minolta Co. , Ltd.
Ramirez Nestor
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