Guide shaft

Abstract

To provide a guide shaft which does not increase its weight too much while suppressing deformation of a guide surface by a rib. [Solution] The guide shaft 100 comprises a first plate-shaped portion 110, a second plate-shaped portion 120 facing the first plate-shaped portion 110, a third plate-shaped portion 130 connecting one end of the first plate-shaped portion 110 and one end of the second plate-shaped portion 120 and having its outer surface 131 as a guide surface, a flat first rib RB1 formed to extend from surface 132, the inner surface of the third plate-shaped portion 130, to surface 112, the inner surface of the first plate-shaped portion 110, and a flat second rib RB2 formed to extend from surface 132, the inner surface of the third plate-shaped portion 130, to surface 122, the inner surface of the second plate-shaped portion 120.

Description

[Technical Field]

[0001] The present invention relates to a guide shaft for a gas bearing. [Background technology]

[0002] For example, in semiconductor manufacturing equipment, flat panel display manufacturing equipment, and other manufacturing equipment, a stage device is provided for positioning a workpiece while holding it. There are various types of stage devices, but devices that require precise positioning generally employ stage devices that use gas bearings as bearings. As described in Patent Documents 1 and 2 below, gas bearings include a guide shaft that extends linearly and a movable body that moves while being guided along the guide shaft.

[0003] An air pad is provided on the movable body at the portion facing the guide shaft. When pressurized air is sprayed from the air pad toward the guide shaft, the pressure of the air causes the guide shaft and movable body to be in a non-contact state. The movable body moves smoothly along the guide shaft with almost no friction, making it possible to position the movable body with high precision. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-21590 [Patent Document 2] Japanese Patent Publication No. 2022-21589 Summary of the Invention [Problem to be solved by the invention]

[0005] The surface of the guide shaft that faces the air pad of the moving body, i.e., the guide surface, is subjected to a force from the pressurized air. The force that the guide surface receives is greatest at the portion of the guide surface that faces the air supply port provided in the air pad.

[0006] If the guide surface of the guide shaft is deformed by the above forces, the movement accuracy and positioning accuracy of the moving body will decrease. Therefore, to prevent deformation of the guide surface, ribs are often provided inside the guide shaft to support and reinforce the guide surface from the inside.

[0007] Conventional ribs are provided so as to connect perpendicularly from the inside of a plate-shaped portion having a guide surface. For example, in the guide shaft described in Patent Document 1, a reinforcing rib is provided so as to extend continuously from the plate-shaped portion on the guide surface side to the plate-shaped portion on the opposite side. In addition, in the guide shaft described in Patent Document 2, multiple reinforcing ribs are provided so as to connect the plate-shaped portion on the guide surface side to the plate-shaped portion on the opposite side. In both configurations, the reinforcing ribs are provided from the guide surface side to the end on the opposite side. As a result, the weight of the guide shaft increases significantly due to the provision of the ribs.

[0008] Increased weight of the guide shaft is undesirable from the viewpoint of material costs, and is particularly undesirable for guide shafts that move while guiding a moving body, such as some guide shafts in XY stages, because increased weight restricts the movement speed.

[0009] The present invention has been made in consideration of such problems, and its purpose is to provide a guide shaft that suppresses deformation of the guide surface with ribs, without increasing the weight too much. [Means for solving the problem]

[0010] In order to solve the above problems, the guide shaft of the present invention is a guide shaft for a gas bearing, and comprises a first plate-shaped portion, a second plate-shaped portion facing the first plate-shaped portion, a third plate-shaped portion connecting one end of the first plate-shaped portion and one end of the second plate-shaped portion and having an outer surface that serves as a guide surface, a flat first rib formed to extend from the inner surface of the third plate-shaped portion to the inner surface of the first plate-shaped portion, and a flat second rib formed to extend from the inner surface of the third plate-shaped portion to the inner surface of the second plate-shaped portion.

[0011] In a guide shaft configured as described above, a first rib is provided to connect the third plate-shaped portion and the first plate-shaped portion, and a second rib is provided to connect the third plate-shaped portion and the second plate-shaped portion. When a force from pressurized air is applied to the guide surface of the third plate-shaped portion, the force is applied to the first plate-shaped portion via the first rib and to the second plate-shaped portion via the second rib. As a result, the existing first and second plate-shaped portions function as members to suppress deformation of the third plate-shaped portion, eliminating the need for a large reinforcing rib extending from the guide surface to the opposite end, as in the past. This minimizes the increase in weight of the guide shaft that would otherwise be caused by the addition of the first rib, while suppressing deformation of the third plate-shaped portion having the guide surface. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a guide shaft in which deformation of the guide surface is suppressed by the rib, but the weight is not increased too much. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram showing the configuration of a stage device equipped with a gas bearing. [Figure 2] 3A and 3B are diagrams illustrating a configuration of a guide shaft according to the present embodiment. [Figure 3] 10A and 10B are diagrams for explaining the position of a rib provided inside a guide shaft. [Figure 4] 10A and 10B are diagrams for explaining the position of a rib provided inside a guide shaft. [Figure 5] FIG. 10 is a diagram showing the configuration of a guide shaft according to a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, the present embodiment will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components in the drawings will be denoted by the same reference numerals as much as possible, and duplicated descriptions will be omitted.

[0015] The guide shaft 100 according to this embodiment is configured as a guide shaft for a hydrostatic gas bearing mounted on a stage device ST. FIG. 1 shows the overall configuration of the stage device ST in a perspective view. For ease of explanation, FIG. 1 shows the X direction, Y direction, and Z direction, which are orthogonal to one another. Prior to explaining the guide shaft 100, the configuration of the stage device ST will first be explained.

[0016] Stage device ST is installed inside a manufacturing apparatus (not shown) for flat panel displays. Stage device ST holds a glass plate GL, which is an object to be processed, and moves and positions the glass plate GL in the X direction, Y direction, etc. Stage device ST may be installed inside a semiconductor exposure apparatus, for example, and may hold and move a silicon wafer, etc., which is an object to be processed.

[0017] The stage device ST includes a support base 200, a guide shaft 100, and an air pad 201.

[0018] The support table 200 is a portion on which a glass plate GL, which is an object to be processed, is placed. The support table 200 is a plate-shaped member made of ceramics such as alumina. The support table 200 holds the glass plate GL on its upper surface and moves in the X direction, Y direction, etc. by a mechanism described later. A holding mechanism for holding the glass plate GL is provided on the upper surface of the support table 200, but is not shown in FIG. 1. The holding mechanism may be, for example, a mechanical clamping mechanism or an electrostatic chuck.

[0019] Mirror members MRX and MRY are attached to the upper surface of support base 200 via spacers SP. Both mirror members MRX and MRY are rod-shaped members made of ceramics. When mirror member MRX is cut perpendicular to its longitudinal direction, its outer shape is rectangular. The same is true for mirror member MRY.

[0020] The mirror member MRX is attached to the support base 200 at a position near the end of the support base 200 on the X-direction side, with its longitudinal direction aligned with the Y-direction. The side surface of the mirror member MRX on the X-direction side is a mirror surface that reflects laser light. By reflecting laser light emitted from a laser length measuring device (not shown) on this mirror surface, it is possible to measure the position of the support base 200 along the X-direction.

[0021] The mirror member MRY is attached to the support base 200 at a position near the end of the support base 200 on the -Y direction side, with its longitudinal direction aligned with the X direction. The side surface of the mirror member MRY on the -Y direction side is a mirror surface that reflects laser light. By reflecting laser light emitted from a laser length measuring device (not shown) on this mirror surface, it is possible to measure the position of the support base 200 along the Y direction.

[0022] The guide shaft 100 is a rod-shaped member for guiding the support base 200 so that the support base 200 moves in the Y direction and the -Y direction. The entire guide shaft 100 is made of ceramics such as alumina. When the guide shaft 100 is cut perpendicular to its longitudinal direction, its outer shape is rectangular. The guide shaft 100 is fixed to the upper surface of the support base 400 (described later) with its longitudinal direction aligned along the Y direction. In this embodiment, two guide shafts 100 are provided, and these are arranged side by side in the X direction while spaced apart from each other. The specific configuration of the guide shaft 100 will be described later.

[0023] The air pad 201 is a member fixed to the support base 200 so as to protrude further downward from the lower surface of the support base 200. Although only one air pad 201 facing the guide shaft 100 from the X direction side is depicted in FIG. 1, a separate air pad (not shown) is provided to face the guide shaft 100 from the -X direction side. In other words, the guide shaft 100 is sandwiched between a pair of air pads lined up in the X direction. In this embodiment, two guide shafts 100 are provided, and therefore a total of four air pads similar to the air pad 201 are provided.

[0024] A small gap is formed between the air pads 201 etc. and the guide shaft 100. Although not shown in the figure, air supply ports, grooves, etc. are formed on the surfaces of the air pads 201 etc. that face the guide shaft 100. When pressurized air is sprayed from the supply ports, the air pads 201 etc. and the guide shaft 100 become non-contact. This allows the support base 200 to move smoothly along the guide shaft 100 (i.e., in the Y direction or -Y direction) with almost no frictional force. Another air pad may be provided between the surface of the guide shaft 100 on the Z direction side and the support base 200.

[0025] As described above, guide shaft 100 and air pads 201 etc. constitute a hydrostatic gas bearing. The entire assembly including support base 200, air pads 201 etc. moves integrally along guide shaft 100, and therefore corresponds to the "moving body" of the hydrostatic gas bearing. Note that guide shaft 100 corresponds to the "fixed body" of the hydrostatic gas bearing, but as will be explained later, guide shaft 100 can move in the X direction and the -X direction together with support base 400.

[0026] The stage device ST further comprises a support base 400, a guide shaft 300, an air pad 401, and the like.

[0027] The support base 400 is a plate-like member made of ceramics such as alumina. The two guide shafts 100 described above are both fixed to the upper surface of the support base 400.

[0028] The guide shaft 300 is a rod-shaped member for guiding the support base 400 so that the support base 400 moves in the X direction and the -X direction. The entire guide shaft 300 is made of ceramics such as alumina. When the guide shaft 300 is cut perpendicular to its longitudinal direction, its outer shape is rectangular. The guide shaft 300 is fixed to the upper surface of a mounting base (not shown) with its longitudinal direction aligned with the X direction. In this embodiment, three guide shafts 300 are provided, and these are arranged side by side in the Y direction while being spaced apart from each other.

[0029] Of the three guide shafts 300, air pads 401, 402, and 403 are provided around the guide shaft 300 that is positioned at the center in the Y direction.

[0030] Air pads 401 and 402 are members fixed to support base 400 so as to protrude further downward from the lower surface of support base 400. Air pad 401 faces guide shaft 300 from the -Y direction side, and air pad 402 faces guide shaft 300 from the Y direction side. In other words, the central guide shaft 300 is sandwiched between the pair of air pads 401 and 402 that are lined up in the Y direction. Air pad 403 is a member fixed to the lower surface of support base 400 in a state facing the upper surface of guide shaft 300.

[0031] A small gap is formed between the air pads 401 etc. and the guide shaft 300. The configuration of the air pads 401 etc. is the same as the configuration of the air pads 201 etc. described above. When pressurized air is ejected from a supply port (not shown) of the air pads 401 etc., the air pads 401 etc. and the guide shaft 300 enter a non-contact state. This allows the support base 400 to move smoothly along the guide shaft 300 (i.e., in the X direction or the -X direction) with almost no frictional force.

[0032] Similar to the periphery of the guide shaft 300 positioned at the center in the Y direction, air pads 401, 402, and 403 may also be arranged around each of the remaining two guide shafts 300. However, in this embodiment, only the air pad 403 is arranged around the remaining two guide shafts 300, and the air pads 401 and 402 are not arranged. In other words, of the three guide shafts 300, only the guide shaft 300 positioned at the center in the Y direction constrains the position of the support base 400 in the Y direction and constrains the support base 400 so that it can move only in the X direction. The other guide shafts 300 simply support the support base 400 from below via the air pads 403.

[0033] As described above, guide shaft 300 and air pad 401 etc. constitute a hydrostatic gas bearing. The entire assembly including support base 400, air pad 401 etc. moves integrally along guide shaft 300, and therefore corresponds to the "moving body" of the hydrostatic gas bearing. Guide shaft 300 corresponds to the "fixed body" of the hydrostatic gas bearing.

[0034] The stage device ST is provided with an actuator (not shown) for applying a driving force to the support base 200 and the support base 400. For example, a linear motor or an air cylinder can be used as the actuator. By using the actuator to move the support base 200 relative to the guide shaft 100, the glass plate GL can be moved and positioned in the Y direction and the -Y direction. In addition, by using the actuator to move the support base 400 relative to the guide shaft 300, the glass plate GL can be moved and positioned in the X direction and the -X direction.

[0035] The specific configuration of the guide shaft 100 will be described mainly with reference to Fig. 2. Fig. 2 schematically shows the configuration of the guide shaft 100 in Fig. 1 when viewed along the Y direction. The width dimension of the guide shaft 100 along the X direction is greater than the height dimension of the guide shaft 100 along the Z direction. The guide shaft 100 has a first plate-shaped portion 110, a second plate-shaped portion 120, a third plate-shaped portion 130, and a fourth plate-shaped portion 140.

[0036] The first plate-shaped portion 110 is a substantially flat portion of the guide shaft 100 that is located closest to the -Z direction. A surface 111 of the first plate-shaped portion 110 on the -Z direction side corresponds to the "outer surface" of the first plate-shaped portion 110, and a surface 112 of the first plate-shaped portion 110 on the Z direction side corresponds to the "inner surface" of the first plate-shaped portion 110. The normal direction of the surface 111 coincides with the -Z direction. The thickness of the first plate-shaped portion 110 is uniform throughout, but the thickness of the first plate-shaped portion 110 may vary depending on the location due to variations during molding, etc. The same applies to the thicknesses of the second plate-shaped portion 120, etc., described below.

[0037] The second plate-shaped portion 120 is a substantially flat portion of the guide shaft 100 that is closest to the Z direction. A surface 121 of the second plate-shaped portion 120 on the Z direction side corresponds to the "outer surface" of the second plate-shaped portion 120, and a surface 122 of the second plate-shaped portion 120 on the -Z direction side corresponds to the "inner surface" of the second plate-shaped portion 120. The normal direction of the surface 121 coincides with the Z direction. Therefore, the first plate-shaped portion 110 and the second plate-shaped portion 120 are parallel to each other. The second plate-shaped portion 120 is the portion that faces the first plate-shaped portion 110 in the Z direction.

[0038] The third plate-shaped portion 130 is a substantially flat portion of the guide shaft 100 that is located closest to the X-direction side. The third plate-shaped portion 130 connects one end (the end on the X-direction side) of the first plate-shaped portion 110 and one end (the end on the X-direction side) of the second plate-shaped portion 120. A surface 131 on the X-direction side of the third plate-shaped portion 130 corresponds to the "outer surface" of the third plate-shaped portion 130, and a surface 132 on the -X-direction side of the third plate-shaped portion 130 corresponds to the "inner surface" of the third plate-shaped portion 130. The surface 131 is a surface perpendicular to the surfaces 111 and 121. The surface 131 faces the air pad 201 described with reference to FIG. 1 and serves as one of the "guide surfaces" for guiding the movement of the support base 200.

[0039] The fourth plate-shaped portion 140 is a substantially flat portion of the guide shaft 100 that is located closest to the −X direction. The fourth plate-shaped portion 140 connects the other end (the end on the −X direction side) of the first plate-shaped portion 110 and the other end (the end on the −X direction side) of the second plate-shaped portion 120. A surface 141 on the −X direction side of the fourth plate-shaped portion 140 corresponds to the “outer surface” of the fourth plate-shaped portion 140, and a surface 142 on the X direction side of the fourth plate-shaped portion 140 corresponds to the “inner surface” of the fourth plate-shaped portion 140. The surface 141 is perpendicular to the surfaces 111 and 121 and parallel to the surface 131. The surface 141 faces an air pad (not shown in FIG. 1 ) and serves as one of the “guide surfaces” for guiding the movement of the support base 200.

[0040] As described above, the guide shaft 100 has the first plate-shaped portion 110, the second plate-shaped portion 120, the third plate-shaped portion 130, and the fourth plate-shaped portion 140, and is a hollow member. The inside of the guide shaft 100 is provided with a plurality of ribs for reinforcing the guide shaft 100 from the inside, such as the first rib RB1 and the second rib RB2 described below.

[0041] The first rib RB1 is a flat reinforcing rib formed to extend from the surface 132 of the third plate-shaped portion 130 to the surface 112 of the first plate-shaped portion 110. The thickness of the first rib RB1 is uniform throughout, but the thickness of the first rib RB1 may vary depending on the location due to variations during molding, etc. The same applies to the thickness of the second rib RB2, etc., described below. The first rib RB1 is inclined with respect to the third plate-shaped portion 130 so that it approaches the first plate-shaped portion 110 as it moves from the third plate-shaped portion 130 toward the -X direction.

[0042] The second rib RB2 is a flat reinforcing rib formed to extend from the surface 132 of the third plate-shaped portion 130 to the surface 122 of the second plate-shaped portion 120. The second rib RB2 is inclined with respect to the third plate-shaped portion 130 so as to approach the second plate-shaped portion 120 as it moves from the third plate-shaped portion 130 toward the -X direction side.

[0043] The third rib RB3 is a flat reinforcing rib formed to extend from the surface 142 of the fourth plate-shaped portion 140 to the surface 112 of the first plate-shaped portion 110. The third rib RB3 is inclined with respect to the fourth plate-shaped portion 140 so as to approach the first plate-shaped portion 110 as it moves from the fourth plate-shaped portion 140 toward the X-direction side.

[0044] The fourth rib RB4 is a flat reinforcing rib formed to extend from the surface 142 of the fourth plate-shaped portion 140 to the surface 122 of the second plate-shaped portion 120. The fourth rib RB4 is inclined with respect to the fourth plate-shaped portion 140 so as to approach the second plate-shaped portion 120 as it moves from the fourth plate-shaped portion 140 toward the X-direction side.

[0045] The fifth rib RB5, the sixth rib RB6, the seventh rib RB7, and the eighth rib RB8 are all flat reinforcing ribs formed to extend from the surface 112 of the first plate-shaped portion 110 to the surface 122 of the second plate-shaped portion 120. They all extend perpendicular to the surface 112 or the surface 122, and are arranged in the order of the sixth rib RB6, the eighth rib RB8, the seventh rib RB7, and the fifth rib RB5 from the -X direction side to the X direction side.

[0046] Of the reinforcing ribs described above, the first rib RB1 and the second rib RB2 are particularly provided as ribs to prevent the third plate-shaped portion 130 from being deformed by the force from the pressurized air when the surface 131, which is the guide surface, receives the force. Also, the third rib RB3 and the fourth rib RB4 are provided as ribs to prevent the fourth plate-shaped portion 140 from being deformed by the force from the pressurized air when the surface 141, which is the guide surface, receives the force.

[0047] 2 represents the force that the surface 131 receives from the pressurized air. When this force causes the third plate-shaped portion 130 to deform into a concave shape, the first rib RB1 receives a force in the direction along the arrow AR11 from the third plate-shaped portion 130. This force is also applied to the first plate-shaped portion 110 via the first rib RB1, so that the first plate-shaped portion 110 receives a force in the direction along the arrow AR13 from the first rib RB1.

[0048] The first plate-shaped portion 110, which receives such a force, pushes back the first rib RB1 with a reaction force in the opposite direction of arrow AR13. The first rib RB1 also pushes back the third plate-shaped portion 130 from the inside with a reaction force in the opposite direction of arrow AR11. Therefore, deformation of the surface 131 of the third plate-shaped portion 130 is suppressed by the force received from the first rib RB1. In this embodiment, the provision of the first rib RB1 enables the first plate-shaped portion 110 to function as a member that suppresses deformation of the third plate-shaped portion 130.

[0049] Furthermore, when the third plate-shaped portion 130 attempts to deform into a concave shape due to the force (arrow AR1) that the surface 131 receives from the pressurized air, the second rib RB2 receives a force in the direction along the arrow AR12 from the third plate-shaped portion 130. This force is also applied to the second plate-shaped portion 120 via the second rib RB2, so that the second plate-shaped portion 120 receives a force in the direction along the arrow AR14 from the second rib RB2.

[0050] The second plate-shaped portion 120, which receives such a force, pushes back the second rib RB2 with a reaction force in the opposite direction of arrow AR14. The second rib RB2 also pushes back the third plate-shaped portion 130 from the inside with a reaction force in the opposite direction of arrow AR12. Therefore, deformation of the surface 131 of the third plate-shaped portion 130 is further suppressed by the force received from the second rib RB2. In this embodiment, the provision of the second rib RB2 allows the second plate-shaped portion 120 to function as a member that suppresses deformation of the third plate-shaped portion 130.

[0051] 2 represents the force that the surface 141 receives from the pressurized air. When this force causes the fourth plate-shaped portion 140 to deform into a concave shape, the third rib RB3 receives a force in the direction along the arrow AR21 from the fourth plate-shaped portion 140. This force is also applied to the first plate-shaped portion 110 via the third rib RB3, so that the first plate-shaped portion 110 receives a force from the third rib RB3 in the direction along the arrow AR23.

[0052] When the first plate-shaped portion 110 receives such a force, it pushes back the third rib RB3 with a reaction force in the opposite direction to that of arrow AR23. The third rib RB3 also pushes back the fourth plate-shaped portion 140 from the inside with a reaction force in the opposite direction to that of arrow AR21. Therefore, deformation of the surface 141 of the fourth plate-shaped portion 140 is suppressed by the force received from the third rib RB3. In this embodiment, the provision of the third rib RB3 allows the first plate-shaped portion 110 to function as a member that suppresses deformation of the fourth plate-shaped portion 140.

[0053] Furthermore, when the fourth plate-shaped portion 140 attempts to deform into a concave shape due to the force (arrow AR2) that the surface 141 receives from the pressurized air, the fourth rib RB4 receives a force in the direction along the arrow AR22 from the fourth plate-shaped portion 140. This force is also applied to the second plate-shaped portion 120 via the fourth rib RB4, so that the second plate-shaped portion 120 receives a force from the fourth rib RB4 in the direction along the arrow AR24.

[0054] The second plate-shaped portion 120, which receives such a force, pushes back the fourth rib RB4 with a reaction force in the opposite direction to that of arrow AR24. Furthermore, the fourth rib RB4 pushes back the fourth plate-shaped portion 140 from the inside with a reaction force in the opposite direction to that of arrow AR22. Therefore, deformation of the surface 141 of the fourth plate-shaped portion 140 is further suppressed by the force received from the fourth rib RB4. In this embodiment, the provision of the fourth rib RB4 allows the second plate-shaped portion 120 to function as a member that suppresses deformation of the fourth plate-shaped portion 140.

[0055] As described above, in the guide shaft according to this embodiment, the provision of the first rib RB1 and the second rib RB2 suppresses deformation of the third plate-shaped portion 130 and the surface 131 due to the force (arrow AR1) received from the pressurized air. Furthermore, the provision of the third rib RB3 and the fourth rib RB4 suppresses deformation of the fourth plate-shaped portion 140 and the surface 141 due to the force (arrow AR2) received from the pressurized air. The guide shaft 100 having the shape shown in Fig. 2 can be manufactured by forming a molded body by, for example, slip casting or extrusion molding, and then firing the molded body.

[0056] A comparative example will now be described. Fig. 5(A) illustrates the configuration of guide shaft 100A, which is a first comparative example, from the same perspective as Fig. 2. In this comparative example, fifth rib RB5, sixth rib RB6, seventh rib RB7, and eighth rib RB8 are provided, but first rib RB1, second rib RB2, third rib RB3, and fourth rib RB4 are not provided. In such a configuration, deformation of surfaces 131, 141, etc. due to the force received from the pressurized air naturally becomes large.

[0057] One possible measure to prevent such deformation is to use a configuration like the second comparative example shown in Fig. 5(B). In the guide shaft 100B according to this comparative example, in addition to the configuration of Fig. 5(A), a reinforcing rib RB10 is provided on the inside. The reinforcing rib RB10 extends perpendicular to the surface 132 of the third plate-shaped portion 130, and is formed so as to extend linearly from the surface 132 to the surface 142.

[0058] In this configuration, when the force of arrow AR1 is applied to surface 131 from pressurized air and the third plate-shaped portion 130 attempts to deform into a concave shape, the reinforcing rib RB10 receives a force from the third plate-shaped portion 130 in the direction along arrow AR31. Reinforcing rib RB10 receives this force and pushes back the third plate-shaped portion 130 from the inside with a reaction force in the opposite direction to arrow AR31. Therefore, deformation of surface 131 of the third plate-shaped portion 130 is suppressed by the force received from reinforcing rib RB10.

[0059] Furthermore, when the force of arrow AR2 is applied to surface 141 from the pressurized air and the fourth plate-shaped portion 140 attempts to deform into a concave shape, reinforcing rib RB10 receives a force from the fourth plate-shaped portion 140 in the direction along arrow AR41. Reinforcing rib RB10 receives such a force and pushes back the fourth plate-shaped portion 140 from the inside with a reaction force in the opposite direction to arrow AR41. Therefore, deformation of surface 141 of the fourth plate-shaped portion 140 is suppressed by the force received from reinforcing rib RB10.

[0060] As a measure to prevent deformation of the surface 131 etc., a configuration like the third comparative example shown in Fig. 5(C) may be considered. In the guide shaft 100C according to this comparative example, in addition to the configuration of Fig. 5(A), reinforcing ribs RB11, RB12, RB13, RB14, and RB15 are provided on the inside. All of these extend perpendicular to the surface 132 etc. of the third plate-shaped portion 130.

[0061] The reinforcing ribs RB11 and RB12 connect the third plate-shaped portion 130 and the seventh rib RB7. The reinforcing rib RB15 connects the seventh rib RB7 and the eighth rib RB8. The reinforcing ribs RB13 and RB14 connect the fourth plate-shaped portion 140 and the eighth rib RB8. The position of the reinforcing rib RB15 in the Z direction is different from the positions of the reinforcing ribs RB11, RB12, RB13, and RB14 in the same direction. Even with this configuration, it is possible to suppress deformation of the surface 131 and the surface 141, as in the example of FIG. 5(B).

[0062] Incidentally, in both guide shaft 100B and guide shaft 100C, reinforcing ribs RB10, RB11, etc. are provided over a wide range, from the third plate-shaped portion 130, which is an end on one side in the X direction, to the fourth plate-shaped portion 140, which is an end on the opposite side. Therefore, the weight of guide shaft 100B and guide shaft 100C ends up increasing significantly due to the provision of reinforcing ribs RB10, etc.

[0063] An increase in the weight of the guide shaft is undesirable from the viewpoint of material costs, and is particularly undesirable for a guide shaft that moves while guiding a moving body, such as the guide shaft 100 mounted on the stage device ST, because an increase in weight restricts the movement speed.

[0064] Therefore, in the guide shaft 100 according to this embodiment, instead of providing the reinforcing rib RB10 etc. shown in Fig. 5, a first rib RB1, a second rib RB2, a third rib RB3, and a fourth rib RB4 are provided. Because the first rib RB1 etc. are relatively small, the increase in weight of the guide shaft 100 due to their provision can be kept to a minimum. Nevertheless, as mentioned above, deformation of the surfaces 131 and 141 can be sufficiently suppressed. In this way, in the guide shaft 100 according to this embodiment, the reinforcing ribs suppress deformation of the guide surfaces, without excessively increasing the overall weight.

[0065] Other advantages of the configuration of the guide shaft 100 according to this embodiment will be described below. As shown in Fig. 2, the first rib RB1 and the fifth rib RB5 are connected to the same location on the surface 112 of the first plate-shaped portion 110. In addition, the second rib RB2 and the fifth rib RB5 are connected to the same location on the surface 122 of the second plate-shaped portion 120.

[0066] As described above, the first plate-shaped portion 110 receives a force from the first rib RB1 in the direction indicated by the arrow AR11. The second plate-shaped portion 120 receives a force from the second rib RB2 in the direction indicated by the arrow AR12. These forces can cause deformation in the guide shaft 100, such as widening the gap between the first plate-shaped portion 110 and the second plate-shaped portion 120. Therefore, in this embodiment, the fifth rib RB5 is provided at the above-described position. By connecting the portion of the first plate-shaped portion 110 to which the force from the first rib RB1 is applied and the portion of the second plate-shaped portion 120 to which the force from the second rib RB2 is applied with the fifth rib RB5, deformation that widens the gap between the first plate-shaped portion 110 and the second plate-shaped portion 120 can be sufficiently suppressed.

[0067] Here, an explanation will be given of the "same location" mentioned above. FIG. 3(A) shows an enlarged view of a portion of the second plate-shaped portion 120. A pair of dotted lines DL51 shown in the figure are imaginary lines that represent the shape of the fifth rib RB5 connected to the second plate-shaped portion 120 when it is extended further toward the second plate-shaped portion 120 along its longitudinal direction. A pair of dotted lines DL21 are imaginary lines that represent the shape of the second rib RB2 connected to the second plate-shaped portion 120 when it is extended further toward the second plate-shaped portion 120 along its longitudinal direction. The dotted line DL2 is an imaginary line that represents the position of the inner surface (i.e., surface 122) of the second plate-shaped portion 120 when the second rib RB2 and the fifth rib RB5 are not provided.

[0068] The hatched area D1 in FIG. 3(A) is the area where the fifth rib RB5 indicated by dotted line DL51, the second rib RB2 indicated by dotted line DL21, and the second plate-shaped portion 120 indicated by dotted line DL2 and the like intersect when the guide shaft 100 is viewed along its longitudinal direction (Y direction). The case where the second rib RB2 and the fifth rib RB5 are connected to the "same location" on the surface 122 of the second plate-shaped portion 120 is defined as the case where such an area D1 exists on the second plate-shaped portion 120. Therefore, for example, if the fifth rib RB5 is provided at a position as shown in FIG. 3(B), the second rib RB2 and the fifth rib RB5 are not connected to the "same location" on the surface 122 of the second plate-shaped portion 120. The definition of the case where the first rib RB1 and the fifth rib RB5 are connected to the "same location" on the surface 112 of the first plate-shaped portion 110 is the same as above.

[0069] In this embodiment, the same consideration has been made with respect to the position of the sixth rib RB6. As shown in Fig. 2, the third rib RB3 and the sixth rib RB6 are connected to the same location on the surface 112 of the first plate-shaped portion 110. In addition, the fourth rib RB4 and the sixth rib RB6 are connected to the same location on the surface 122 of the second plate-shaped portion 120.

[0070] As described above, the first plate-shaped portion 110 receives a force from the third rib RB3 in the direction indicated by the arrow AR21. The second plate-shaped portion 120 receives a force from the fourth rib RB4 in the direction indicated by the arrow AR22. These forces can cause deformation in the guide shaft 100, such as widening the gap between the first plate-shaped portion 110 and the second plate-shaped portion 120. Therefore, in this embodiment, the sixth rib RB6 is provided at the above-described position. By connecting the portion of the first plate-shaped portion 110 to which the force from the third rib RB3 is applied and the portion of the second plate-shaped portion 120 to which the force from the fourth rib RB4 is applied with the sixth rib RB6, deformation that widens the gap between the first plate-shaped portion 110 and the second plate-shaped portion 120 can be sufficiently suppressed. The definition of "connected at the same location" is the same as described above.

[0071] 2, the first rib RB1 and the second rib RB2 are connected to different locations on the surface 132 of the third plate-shaped portion 130. In this configuration, the third plate-shaped portion 130 is supported from the inside at multiple locations, which further reduces deformation of the third plate-shaped portion 130 and the surface 131.

[0072] Here, an explanation will be given of the "different portions" mentioned above. FIG. 4(A) shows an enlarged view of the third plate-shaped portion 130 and its vicinity. A pair of dotted lines DL12 shown in the figure are imaginary lines representing the shape of the first rib RB1 connected to the third plate-shaped portion 130 when it is extended further along its longitudinal direction toward the third plate-shaped portion 130. A pair of dotted lines DL22 are imaginary lines representing the shape of the second rib RB2 connected to the third plate-shaped portion 130 when it is extended further along its longitudinal direction toward the third plate-shaped portion 130. A dotted line DL3 is an imaginary line representing the position of the inner surface (i.e., surface 132) of the third plate-shaped portion 130 when the first rib RB1 and the second rib RB2 are not provided.

[0073] As is clear from FIG. 4(A), when the guide shaft 100 is viewed along its longitudinal direction (Y direction), there is no region where the first rib RB1 indicated by dotted line DL12, the second rib RB2 indicated by dotted line DL22, and the third plate-shaped portion 130 indicated by dotted line DL3 and the like intersect with one another. The case where the first rib RB1 and the second rib RB2 are connected to "different locations" on the surface 132 of the third plate-shaped portion 130 is defined as a case where no intersecting region as described above exists on the third plate-shaped portion 130. This definition is synonymous with the case where the first rib RB1 and the second rib RB2 are not connected to the "same location" defined above.

[0074] Note that, when the force from the pressurized air is applied to a relatively narrow range on the surface 131 of the third plate-shaped portion 130, a different configuration may be used. For example, when the force from the pressurized air is applied locally to a central position in the Z direction on the surface 131, the configuration shown in FIG. 4(B) may be used. The hatched region D2 in FIG. 4 is the region where the first rib RB1 indicated by the dotted line DL12, the second rib RB2 indicated by the dotted line DL22, and the third plate-shaped portion 130 indicated by the dotted line DL3, etc. intersect when the guide shaft 100 is viewed along its longitudinal direction (Y direction). That is, in the example of FIG. 4(B), the first rib RB1 and the second rib RB2 are connected to the same location on the surface 132 of the third plate-shaped portion 130. This location corresponds to the position where the force from the pressurized air is locally applied.

[0075] In such a configuration, the portion of the third plate-shaped portion 130 to which local force is applied is supported in a concentrated manner from the inside by both the first rib RB1 and the second rib RB2, thereby sufficiently suppressing deformation of the third plate-shaped portion 130 and the surface 131.

[0076] The same applies to the locations where the third rib RB3 and the fourth rib RB4 are connected to the surface 142 of the fourth plate-shaped portion 140. In this embodiment, the third rib RB3 and the fourth rib RB4 are connected to different locations on the surface 142 of the fourth plate-shaped portion 140. In this configuration, the fourth plate-shaped portion 140 is supported from the inside at multiple locations, which further reduces deformation of the fourth plate-shaped portion 140 and the surface 142. The definition of "connected to different locations" is the same as that described above.

[0077] In cases where the force from the pressurized air is applied to a relatively narrow range on the surface 142 of the fourth plate-shaped portion 140, the third rib RB3 and the fourth rib RB4 may be connected to the same location on the surface 142 of the fourth plate-shaped portion 140, as in the configuration of Figure 4(B).

[0078] Various modifications can be made to the configuration of the guide shaft 100 described above. For example, the numbers of the fifth rib RB5, sixth rib RB6, seventh rib RB7, and eighth rib RB8 extending perpendicular to the surface 111 may be changed as appropriate depending on the dimension of the first plate-shaped portion 110 along the X direction, etc. The fifth rib RB5, sixth rib RB6, seventh rib RB7, and eighth rib RB8 may all be eliminated.

[0079] Furthermore, a configuration similar to the guide axis 100 described above may be applied to other guide axes (or all guide axes) provided in the stage device ST. For example, of the three guide axes 300 shown in FIG. 1, the guide axis 300 located in the center in the Y direction receives a force from the compressed air from both sides along the same direction. For this reason, it is preferable to apply a configuration similar to that of the guide axis 100 of this embodiment to the configuration of this guide axis 300.

[0080] In this embodiment, both the surface 131 at the end of the guide shaft 100 on the X-direction side and the surface 141 at the opposite end function as guide surfaces that receive pressurized air from the air pad. For example, in a configuration in which only the surface 131 functions as a guide surface, the first rib RB1 and the second rib RB2 may be provided, while the third rib RB3 and the fourth rib RB4 may not be provided.

[0081] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Design modifications to these specific examples made by a person skilled in the art as appropriate are also included within the scope of the present disclosure as long as they comprise the features of the present disclosure. The elements of the above-described specific examples, as well as their arrangement, conditions, shape, etc., are not limited to those exemplified and can be modified as appropriate. The elements of the above-described specific examples can be combined in various ways as appropriate, as long as no technical contradictions arise. [Explanation of symbols]

[0082] 100: Guide shaft 110: First plate-shaped portion 120: Second plate-shaped part 130: Third plate-shaped part 140: Fourth plate-shaped part 111,112,121,122,131,132,141,142: Surface RB1: First rib RB2: Second rib RB3: 3rd rib RB4: 4th rib RB5: 5th rib RB6: 6th Rib

Claims

1. A guide shaft for a gas bearing, A first plate-shaped portion; a second plate-shaped portion facing the first plate-shaped portion; a third plate-shaped portion connecting one end of the first plate-shaped portion and one end of the second plate-shaped portion, the outer surface of which serves as a guide surface; a flat first rib formed so as to extend from the inner surface of the third plate-shaped portion to the inner surface of the first plate-shaped portion; a second rib having a flat plate shape formed so as to extend from the inner surface of the third plate-shaped portion to the inner surface of the second plate-shaped portion.

2. a fourth plate-shaped portion connecting the other end of the first plate-shaped portion and the other end of the second plate-shaped portion, the outer surface of which serves as a guide surface; a flat third rib formed so as to extend from the inner surface of the fourth plate-shaped portion to the inner surface of the first plate-shaped portion; The guide shaft according to claim 1 , further comprising: a fourth rib in the form of a flat plate formed so as to extend from the inner surface of the fourth plate-shaped portion to the inner surface of the second plate-shaped portion.

3. The guide shaft according to claim 1 , further comprising a fifth rib in the form of a flat plate formed so as to extend from the inner surface of the first plate-shaped portion to the inner surface of the second plate-shaped portion.

4. the first rib and the fifth rib are connected to the same location on the inner surface of the first plate-shaped portion, The guide shaft according to claim 3 , wherein the second rib and the fifth rib are connected to the same location on the inner surface of the second plate-shaped portion.

5. The guide shaft according to claim 2 , further comprising a sixth rib in the form of a flat plate formed so as to extend from the inner surface of the first plate-shaped portion to the inner surface of the second plate-shaped portion.

6. the third rib and the sixth rib are connected to the same location on the inner surface of the first plate-shaped portion, The guide shaft according to claim 5 , wherein the fourth rib and the sixth rib are connected to the same location on the inner surface of the second plate-shaped portion.

7. The guide shaft according to claim 1 , wherein the first rib and the second rib are connected to different positions on the inner surface of the third plate-shaped portion.

8. The guide shaft according to claim 2 , wherein the third rib and the fourth rib are connected to different positions on the inner surface of the fourth plate-shaped portion.

9. The guide shaft according to claim 1 , wherein the first rib and the second rib are connected to the same location on the inner surface of the third plate-shaped portion.

10. The guide shaft according to claim 2 , wherein the third rib and the fourth rib are connected to the same location on the inner surface of the fourth plate-shaped portion.

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