Machine element or mechanism – Control lever and linkage systems – Multiple controlling elements for single controlled element
Reexamination Certificate
2001-12-19
2003-10-07
Schwartz, Christopher P. (Department: 3683)
Machine element or mechanism
Control lever and linkage systems
Multiple controlling elements for single controlled element
C074S490130
Reexamination Certificate
active
06629471
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an X-Y stage apparatus having a stage on which a workpiece is placed and which can move in X- and Y-directions.
2. Description of the Related Art
Referring to
FIG. 1
, a stage apparatus on which a moving body
12
can move only in one axial direction will be described. This stage apparatus employs a static pressure air bearing (not shown). A beam
11
is fixed on a base
10
. The moving body
12
is combined with the beam
11
. The moving body
12
can move along the beam
11
acting as a guide. The moving body
12
is realized by, for example, the movable section of a linear motor. The beam
11
and the moving body
12
are composed of a material such as ceramics which has high rigidity and the dimension of which can be easily managed.
Next, an X-Y stage apparatus using static pressure air bearings (not shown) will be described with reference to FIG.
2
. In
FIG. 2
, two guide rails
13
and
14
are disposed on a base
10
at a predetermined interval. Moving bodies
15
and
16
are combined with the guide rails
13
and
14
, respectively. The moving bodies
15
and
16
can move along the guide rails
13
and
14
, respectively. The moving bodies
15
and
16
are connected to each other through the beam
11
. As a result, when the moving bodies
15
and
16
move along the guide rails
13
and
14
, the beam
11
also moves. A moving body
12
is combined with the beam
11
. The moving body
12
can move along the beam
11
acting as a guide. Each of the moving bodies
12
,
15
, and
16
is realized by the movable section of a linear motor.
Incidentally, there is a tendency that the size of X-Y stage apparatuses increases. In the X-Y stage apparatus shown in
FIG. 2
, the length of the beam
11
is increased to increase the amount of movement (stroke) of the moving body
12
. Further, the mass of a workpiece placed on the moving body
12
is also increased. As a result, the amount of flexure of the beam
11
cannot be neglected. When the beam
11
is flexed, the moving body
12
cannot move smoothly.
In the X-Y stage apparatus shown in
FIG. 2
, it is impossible for a support member to support the beam
11
at the center thereof to minimize the amount of flexure of the beam
11
. This is because that the four surfaces of the beam
11
around the periphery thereof act as guide surfaces. That is, the support member cannot be interposed between the base
10
and the beam
11
. Further, since the beam
11
itself moves in the same direction as those of the guide rails
13
and
14
, the support member must be moved following the movement of the beam
11
.
An X-Y stage apparatus proposed by the inventors will be described with reference to FIG.
3
. The X-Y stage apparatus is disclosed in Japanese Unexamined Patent Publication No. 2000-155186.
The fixed sections of the X-Y stage apparatus are a base
20
having an upper surface of which acts as a guide surface, and guide rails
21
and
22
which are fixed on the base
20
at an interval.
FIG. 3
shows the three directions of X-, Y-, and Z-axes that are orthogonal to each other. The guide rails
21
and
22
. have guide surfaces
21
a and
22
a that extend in the Y-axis direction and face to each other. In this X-Y stage apparatus, the movable sections that are linearly guided along the guide surfaces
21
a
and
22
a
in the Y-axis direction are-a Y-slider
23
, static pressure air bearing pads
25
-
1
,
25
-
2
.
25
-
3
, and
25
-
4
and static pressure air bearing pads
27
-
1
,
27
-
2
, and
27
-
3
. The Y-slider
23
is interposed between the guide rails
21
and
22
and includes a beam
23
-
1
extending in the X-axis direction and T-shaped sections
23
-
2
at both ends of the beam
23
-
1
.
The static pressure air bearing pads
25
-
1
to
25
-
4
are disposed on sides of the two T-shaped sections
23
-
2
of the Y-slider
23
through couplings (not shown) each having a one-degree-of-freedom about the rotation around the Z-axis, respectively. The static pressure air bearing pads
25
-
1
and
25
-
2
eject compressed air onto the guide surface
21
a
, and the static pressure air-,bearing pads
25
-
3
and
25
-
4
eject compressed air onto the guide surface
22
a
. The static pressure air bearing pads
27
-
1
and
27
-
2
are disposed on the lower surface of the T-shaped section
23
-
2
at one end of the beam
23
-
1
, and the static pressure air bearing pad
27
-
3
is disposed on the lower surface of the beam
23
-
1
at the other end thereof. The static pressure air bearing pads
27
-
1
to
27
-
3
eject compressed air onto the upper surface of the base
20
.
Note that the static pressure air bearing pads
27
-
1
and
27
-
2
are disposed at positions that are approximately symmetrical with respect to the central axis of the Y-slider
23
, that is, the central axis of the beam
23
-
1
. In contrast, the static pressure air bearing pad
27
-
3
is disposed at a position corresponding to the central axis of the Y-slider
23
. That is, the static pressure air bearing pads
27
-
1
,
27
-
2
, and
27
-
3
are disposed such that the line segments that connect the centers of them form an isosceles triangle.
Further, in
FIG. 3
, the movable sections, which are linearly guided in the X-axis direction while being also linearly guided in the Y-axis direction, are an X-slider
24
, static pressure air bearing pads
25
-
5
,
25
-
6
,
25
-
7
, and
25
-
8
and static pressure air bearing pads
27
-
4
,
27
-
5
, and
27
-
6
. The X-slider
24
is combined with the Y-slider
23
so as to move along the beam
23
-
1
. The beam
23
-
1
has a square cross section including two side surfaces each extending in the X-axis direction. The X-slider
24
has an approximately inverted-U-shaped cross section having two inner surfaces facing the two side surfaces of the beam
23
-
1
of the Y-slider
23
. The static pressure air bearing pads
25
-
5
to
25
-
8
are disposed on the two inner surfaces of the X-slider
24
through couplings (not shown) each having a one-degree-of-freedom about the rotation around the z-axis. The static pressure air bearing pads
27
-
4
to
27
-
6
are disposed on the lower surface of the X-slider
24
. In the Y-slider
23
, the two side surfaces of the beam
23
-
1
extending in the X-axis direction are formed as reference surfaces for guiding the X-slider
24
. The static pressure air bearing pads
25
-
5
to
25
-
8
eject compressed air onto the side surfaces of the beam
23
-
1
. The static pressure air bearing pads
27
-
4
to
27
-
6
eject compressed air onto the upper surface of the base
20
.
The X-Y stage apparatus employs a pair of linear motors
31
as the drive source of the Y-slider
23
. One of the linear motors
31
is arranged between the guide rail
21
and the Y-slider
23
, and the other of them is interposed between the guide rail
22
and the Y-slider
23
. In contrast, a linear motor
32
is arranged between the Y-slider
23
and the X-slider
24
and used as the drive source of the X-slider
24
. The linear motors
31
and
32
have the same known structure. Thus, one of the linear motors
31
will be described briefly. The linear motor
31
is arranged such that movable coils (not shown) extending from the T-shaped section
23
-
2
of the Y-slider
23
are disposed in the gap formed between a multiplicity of upper permanent magnets
31
-
1
disposed in the Y-axis direction and a multiplicity of lower permanent magnets
31
-
2
disposed in the Y-axis direction.
In the X-Y stage apparatus, a combination of a linear scale and a linear sensor is necessary to each linear motor so as to act as a position sensor for position control, in addition to the above components. Further, a synchronous control system is also necessary to drive the pair of linear motors
31
in synchronism. Furthermore, power supply lines for the linear motors of the moving Y- and X-sliders
23
and
24
, signal wires for the sensor, and air pipings for static pressure air bearings are necessary. All of them are made
Arent Fox Kintner & Plotkin & Kahn, PLLC
Schwartz Christopher P.
Sumitomo Heavy Industrie's, Ltd.
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