Horizontal articulated robot

Abstract

To provide a horizontal articulated robot that can be miniaturized in the horizontal direction while enabling increase in the amount of lifting of an arm without changing a height of the horizontal articulated robot when the arm has descended to a lower limit position.SOLUTION: In a horizontal articulated robot 1, a first distance, which is a horizontal distance between a first rotational center as the center of rotation of a first arm part 15 relative to a body part 13 and a second rotational center as the center of rotation of a second arm part 16 relative to the first arm part 15, is shorter than a second distance, which is a horizontal distance between the third rotational as the center of rotation of a third arm part 17 relative to the second arm part 16 and the second rotational center. Also, when an arm 12 has descended to a lower limit position, an upper end part of an arm lifting mechanism 20 is positioned on the side of a base end part of the first arm part 15.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a horizontal articulated robot whose arm operates in the horizontal direction.

Background Art

[0002] Conventionally, a horizontal articulated robot for transporting semiconductor wafers has been known (see, for example, Patent Document 1). The horizontal articulated robot described in Patent Document 1 is incorporated and used in a semiconductor manufacturing system. The semiconductor manufacturing system includes an EFEM (Equipment Front End Module), and the horizontal articulated robot constitutes a part of the EFEM. The EFEM includes a housing in which the horizontal articulated robot is accommodated.

[0003] The horizontal articulated robot described in Patent Document 1 includes a hand on which a semiconductor wafer is mounted, an arm to which the hand is rotatably connected at the tip side, and a main body portion to which the base end side of the arm is rotatably connected. The arm includes a first arm portion whose base end side is rotatably connected to the main body portion, a second arm portion whose base end side is rotatably connected to the tip side of the first arm portion, and a third arm portion whose base end side is rotatably connected to the tip side of the second arm portion. A hand is rotatably connected to the tip side of the third arm portion. The first arm portion is disposed above the main body portion, the second arm portion is disposed above the first arm portion, the third arm portion is disposed above the second arm portion, and the hand is disposed above the third arm portion.

[0004] Further, the horizontal articulated robot described in Patent Document 1 includes an arm lifting mechanism for lifting and lowering the arm. The arm lifting mechanism includes a drive mechanism having a ball screw and a motor or the like for rotating the screw shaft of the ball screw, and a guide mechanism having a guide rail and a guide block or the like engaged with the guide rail. The arm lifting mechanism is housed inside the main body portion and is disposed below the first arm portion. That is, the ball screw and the guide rail constituting a part of the arm lifting mechanism are disposed below the first arm portion. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2015-36186 [Overview of the project] [Problems that the invention aims to solve]

[0006] In the horizontal articulated robot described in Patent Document 1, if the amount of arm movement can be increased without changing the height of the horizontal articulated robot when the arm is lowered to its lowest position, the horizontal articulated robot can be used in various semiconductor manufacturing systems, thereby increasing its versatility. Therefore, it is preferable that the horizontal articulated robot described in Patent Document 1 be designed in this way. Furthermore, it is preferable that the horizontal articulated robot installed inside a housing in a semiconductor manufacturing system be compact in the horizontal direction.

[0007] Therefore, the object of the present invention is to provide a horizontal articulated robot in which the arm moves horizontally, which can be miniaturized in the horizontal direction, while increasing the amount of arm movement without changing the height of the horizontal articulated robot when the arm is lowered to its lowest position. [Means for solving the problem]

[0008] To solve the above problems, the present invention provides a horizontal articulated robot in which the arm moves in the horizontal direction, comprising: a hand on which an object to be transported is mounted; an arm to which the hand is rotatably connected at the tip; a main body to which the base end of the arm is rotatably connected; and an arm lifting mechanism for raising and lowering the arm, wherein the arm comprises a first arm portion to which the base end is rotatably connected at the main body, and a second arm portion to which the base end is rotatably connected at the tip of the first arm portion, the lower side of the first arm portion being connected to the upper side of the main body, the lower side of the second arm portion being connected to the upper side of the first arm portion, and the tip of the second arm portion The base end of the third arm portion, which constitutes part of the arm, or the base end of the hand, is rotatably connected to the side. The first distance, which is the horizontal distance between the first pivot center, which is the pivot center of the first arm portion relative to the main body, and the second pivot center, which is the pivot center of the second arm portion relative to the first arm portion, is shorter than the second distance, which is the horizontal distance between the third pivot center, which is the pivot center of the third arm portion or hand connected to the second arm portion, and the second pivot center. When the arm is lowered to its lowest position, the upper end of the arm lifting mechanism is positioned to the side of the base end of the first arm portion.

[0009] In the horizontal articulated robot of the present invention, when the arm is lowered to its lowest position, the upper end of the arm lifting mechanism is positioned to the side of the base end of the first arm. Therefore, in the present invention, compared to the case where the entire arm lifting mechanism is positioned below the first arm, it is possible to increase the height of the arm lifting mechanism without changing the height of the horizontal articulated robot when the arm is lowered to its lowest position. Consequently, in the present invention, it is possible to increase the amount of arm lifting without changing the height of the horizontal articulated robot when the arm is lowered to its lowest position.

[0010] Furthermore, in the present invention, the first distance, which is the horizontal distance between the first pivot center, which is the pivot center of the first arm portion relative to the main body, and the second pivot center, which is the pivot center of the second arm portion relative to the first arm portion, is shorter than the second distance, which is the horizontal distance between the third pivot center, which is the pivot center of the third arm portion or hand connected to the second arm portion, and the second pivot center. Therefore, it becomes possible to shorten the length of the first arm portion.

[0011] Therefore, in the present invention, even if the upper end of the arm lifting mechanism is positioned to the side of the base end of the first arm when the arm is lowered to its lowest position, it becomes possible to position the upper end of the arm lifting mechanism to the side of the shorter first arm, and as a result, it becomes possible to miniaturize the horizontal articulated robot in the horizontal direction. In other words, in the present invention, even if it is possible to increase the amount of arm lifting without changing the height of the horizontal articulated robot when the arm is lowered to its lowest position, it becomes possible to miniaturize the horizontal articulated robot in the horizontal direction.

[0012] In the present invention, for example, the arm lifting mechanism includes a ball screw for raising and lowering the arm and a guide rail for guiding the arm in the vertical direction, wherein the screw shaft of the ball screw is positioned such that its axial direction coincides with the vertical direction, and the guide rail is positioned such that its longitudinal direction coincides with the vertical direction, and when the arm is lowered to its lower limit position, the upper ends of the screw shaft and the guide rail are positioned to the side of the base end of the first arm portion.

[0013] In the present invention, when the arm is lowered to its lowest position, it is preferable that the upper end of the arm lifting mechanism is positioned below the lower end of the second arm. With this configuration, even if there is no notch or the like formed on the second arm to prevent interference between the second arm and the arm lifting mechanism, it is possible to prevent interference between the second arm and the arm lifting mechanism when the second arm rotates.

[0014] In the present invention, for example, when the first arm and the second arm are positioned at a predetermined reference position relative to the main body with the arms overlapping each other, the longitudinal direction of the first arm and the second arm is defined as the longitudinal direction of the arm, one side of the longitudinal direction of the arm is defined as the first direction side, and the opposite side of the first direction side is defined as the second direction side. When the first arm and the second arm are positioned at a reference position relative to the main body with the arms overlapping each other and the arms have been lowered to their lowest position, the base end of the first arm is the end on the first direction side of the first arm and is positioned on the second direction side of the upper end of the arm lifting mechanism, and the tip of the second arm is the end on the first direction side of the second arm and is positioned above the arm lifting mechanism. In this case, it is possible to increase the amount of arm lifting without changing the height of the horizontal articulated robot when the arm has been lowered to its lowest position, and it is possible to miniaturize the horizontal articulated robot in the longitudinal direction of the arm.

[0015] In the present invention, the lifting mechanism is housed inside the main body, and when the first arm and the second arm are positioned relative to the main body in a reference position with respect to the main body and overlapping each other, the first-direction side end of the second arm is preferably positioned at the same position as the first-direction side end of the main body in the lateral direction of the arm. With this configuration, it is possible to increase the amount of lifting and lowering of the arm without changing the height of the horizontal articulated robot when the arm is lowered to its lower limit position, while also making the horizontal articulated robot more compact in the lateral direction of the arm.

[0016] In the present invention, for example, the base end of the third arm is rotatably connected to the tip end of the second arm, and the base end of the hand is rotatably connected to the tip end of the third arm.

[0017] In the present invention, it is preferable that the horizontal articulated robot includes a first arm portion drive mechanism that rotates the first arm portion with respect to the main body portion, a second arm portion drive mechanism that rotates the second arm portion with respect to the first arm portion, a third arm portion drive mechanism that rotates the third arm portion with respect to the second arm portion, and a hand drive mechanism that rotates the hand with respect to the third arm portion. With such a configuration, it becomes possible to increase the degree of freedom of the operation of the horizontal articulated robot.

Advantages of the Invention

[0018] As described above, in the present invention, in a horizontal articulated robot in which the arm operates in the horizontal direction, even if it is possible to increase the amount of elevation and depression of the arm without changing the height of the horizontal articulated robot when the arm has descended to the lower limit position, it becomes possible to miniaturize the horizontal articulated robot in the horizontal direction.

Brief Description of the Drawings

[0019] [Figure 1] It is a plan view for explaining the configuration of the horizontal articulated robot according to an embodiment of the present invention. [Figure 2] It is a plan view of different states of the horizontal articulated robot shown in FIG. 1. [Figure 3] It is a side view of the horizontal articulated robot shown in FIG. 2. [Figure 4] It is a side view of the horizontal articulated robot shown in FIG. 3 in a state where the arm is rising. [Figure 5] It is a block diagram for explaining the configuration of the horizontal articulated robot shown in FIG. 2. [Figure 6] It is a view for explaining the configuration of the arm elevating mechanism in the E-E direction of FIG. 3.

Embodiments for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0021] (Configuration of the Horizontal Articulated Robot) Figure 1 is a plan view illustrating the configuration of a horizontal articulated robot 1 according to an embodiment of the present invention. Figure 2 is a plan view of the horizontal articulated robot 1 shown in Figure 1 in different states. Figure 3 is a side view of the horizontal articulated robot 1 shown in Figure 2. Figure 4 is a side view of the horizontal articulated robot 1 shown in Figure 3 with the arm 12 raised. Figure 5 is a block diagram illustrating the configuration of the horizontal articulated robot 1 shown in Figure 2. Figure 6 is a diagram illustrating the configuration of the arm lifting mechanism 20 from the EE direction in Figure 3.

[0022] The horizontal articulated robot 1 (hereinafter referred to as "Robot 1") in this embodiment is an industrial robot for transporting semiconductor wafers 2 (hereinafter referred to as "Wafer 2"), which are the objects to be transported. The wafer 2 is formed in the shape of a thin disc. Robot 1 is used by being incorporated into a semiconductor manufacturing system 3. In the following description, the X direction in Figure 1, etc., which is perpendicular to the vertical direction, will be referred to as the "left-right direction," and the Y direction in Figure 1, etc., which is perpendicular to both the vertical and left-right directions, will be referred to as the "front-back direction." Furthermore, the Y1 direction side in Figure 1, etc., which is one side of the front-back direction, will be referred to as the "front," and the Y2 direction side in Figure 1, etc., which is the opposite side, will be referred to as the "back."

[0023] The semiconductor manufacturing system 3 includes an EFEM4. Robot 1 constitutes part of the EFEM4. The EFEM4 includes, for example, a plurality of load ports 7 that open and close a FOUP6 ​​in which wafers 2 are housed, and a housing 8 in which robot 1 is housed. The housing 8 is formed in the shape of a rectangular box. When viewed from above, the outer shape of the housing 8 is a long, narrow rectangle in the left-right direction. The plurality of load ports 7 are arranged, for example, on the front side of the housing 8. The plurality of load ports 7 are also arranged with a certain distance between them in the left-right direction.

[0024] Robot 1 comprises two hands 11 on which wafers 2 are mounted, an arm 12 to which the two hands 11 are rotatably connected at their tip ends and which moves horizontally, and a main body 13 to which the base end of the arm 12 is rotatably connected. The hands 11 are formed to have a roughly Y shape when viewed from above. The arm 12 consists of a first arm portion 15 whose base end is rotatably connected to the main body 13, a second arm portion 16 whose base end is rotatably connected to the tip end of the first arm portion 15, and a third arm portion 17 whose base end is rotatably connected to the tip end of the second arm portion 16. The base ends of the two hands 11 are rotatably connected to the tip end of the third arm portion 17. The base ends of the two hands 11 overlap in the vertical direction.

[0025] The hand 11, the first arm section 15, the second arm section 16, and the third arm section 17 rotate with the vertical direction as the axis of rotation. The upper and lower surfaces of the first arm section 15, the second arm section 16, and the third arm section 17 are planes perpendicular to the vertical direction. The first arm section 15 is connected to the upper side of the main body section 13. The second arm section 16 is connected to the upper side of the first arm section 15. The third arm section 17 is connected to the upper side of the second arm section 16. The hand 11 is connected to the upper side of the third arm section 17.

[0026] Specifically, the lower side of the first arm portion 15 is connected to the upper side of the main body portion 13, the lower side of the second arm portion 16 is connected to the upper side of the first arm portion 15, the lower side of the third arm portion 17 is connected to the upper side of the second arm portion 16, and the lower side of the hand portion 11 is connected to the upper side of the third arm portion 17. The second arm portion 16 is positioned above the first arm portion 15, the third arm portion 17 is positioned above the second arm portion 16, and the hand portion 11 is positioned above the third arm portion 17.

[0027] Furthermore, the robot 1 includes an arm lifting mechanism 20 for raising and lowering the arm 12, a first arm drive mechanism 21 for rotating the first arm 15 relative to the main body 13, a second arm drive mechanism 22 for rotating the second arm 16 relative to the first arm 15, a third arm drive mechanism 23 for rotating the third arm 17 relative to the second arm 16, and a hand drive mechanism 24 for rotating the hand 11 relative to the third arm 17. In this embodiment, the robot 1 is equipped with two hand drive mechanisms 24 that rotate each of the two hands 11 individually.

[0028] The pivot centers of the two hands 11 with respect to the third arm 17 coincide. If we define the pivot center of the first arm 15 with respect to the main body 13 as the first pivot center C1, the pivot center of the second arm 16 with respect to the first arm 15 as the second pivot center C2, the pivot center of the third arm 17 with respect to the second arm 16 as the third pivot center C3, and the pivot center of the hand 11 with respect to the third arm 17 as the fourth pivot center C4, then the first distance D1, which is the horizontal distance between the first pivot center C1 and the second pivot center C2, is shorter than the second distance D2, which is the horizontal distance between the second pivot center C2 and the third pivot center C3. Also, the second distance D2 is shorter than the third distance D3, which is the horizontal distance between the third pivot center C3 and the fourth pivot center C4.

[0029] Therefore, in this embodiment, the length of the first arm portion 15 (the longitudinal length of the first arm portion 15) is shorter than the length of the second arm portion 16 (the longitudinal length of the second arm portion 16), and the length of the second arm portion 16 is shorter than the length of the third arm portion 17 (the longitudinal length of the third arm portion 17).

[0030] The main body 13 comprises a housing 26 and a lifting body 27 to which the base end of the first arm 15 is rotatably connected. The housing 26 is formed as a rectangular parallelepiped, elongated in the vertical direction. A projection 26a is formed at the rear end of the housing 26, projecting upward. That is, the height of the rear end of the housing 26 is greater than the height of the front part of the housing 26. The projection 26a is located behind the base end of the first arm 15. The upper surface of the projection 26a is a plane perpendicular to the vertical direction. The upper surface of the housing 26 in front of the projection 26a is also a plane perpendicular to the vertical direction. The height of the projection 26a relative to the upper surface of the front part of the housing 26 is approximately equal to the thickness (vertical thickness) of the first arm 15.

[0031] The lifting body 27 is movable up and down relative to the housing 26. As shown in Figure 3, when the arm 12 is lowered to its lowest position, most of the lifting body 27 is housed inside the housing 26. The lifting body 27 comprises a lifting body main body 27a to which the base end of the first arm portion 15 is rotatably connected at its upper end, and a holding portion 27b that protrudes rearward from the lower end of the lifting body main body 27a. The lifting body main body 27a is positioned in front of the protruding portion 26a of the housing 26. The upper end of the lifting body main body 27a is positioned above the upper surface of the portion of the housing 26 in front of the protruding portion 26a. A through hole is formed in the upper end of the portion of the housing 26 in front of the protruding portion 26a, in which a part of the lifting body main body 27a is positioned.

[0032] The arm lifting mechanism 20 raises and lowers the lifting body 27. That is, by raising and lowering the lifting body 27, the arm lifting mechanism 20 raises and lowers the arm 12 together with the lifting body 27. The arm lifting mechanism 20 also raises and lowers the arm 12 together with the lifting body 27 between the lower limit position of the arm 12 shown in Figure 3 and the upper limit position of the arm 12 shown in Figure 4. As shown in Figure 6, the arm lifting mechanism 20 includes a ball screw 28 for raising and lowering the arm 12 together with the lifting body 27, a motor 30 for rotating the screw shaft 29 of the ball screw 28, and guide rails 31 and guide blocks 32 for guiding the arm 12 in the vertical direction together with the lifting body 27. The arm lifting mechanism 20 is located inside the housing 26. That is, the arm lifting mechanism 20 is housed inside the main body 13.

[0033] The screw shaft 29 is positioned so that its axial direction coincides with its vertical direction. The screw shaft 29 is rotatably held by a frame located inside the housing 26. The nut member 33 of the ball screw 28 is attached to the holding portion 27b of the lifting body 27. The nut member 33 engages with the screw shaft 29. A pulley 35 is fixed to the lower end of the screw shaft 29. The motor 30 is fixed inside the housing 26. A pulley 36 is fixed to the output shaft of the motor 30. A belt 37 is stretched between pulleys 35 and 36. The motor 30 is electrically connected to the control unit 38 of the robot 1.

[0034] The guide rails 31 are arranged so that their longitudinal and vertical directions coincide. The guide rails 31 are fixed to a frame located inside the housing 26. In this embodiment, two guide rails 31 are installed with a gap between them in the left-right direction. The guide block 32 is attached to the holding portion 27b of the lifting body 27. The guide block 32 engages with the guide rail 31 from the front. In this embodiment, two guide blocks 32, which are spaced apart in the vertical direction, engage with one guide rail 31.

[0035] As described above, the arm lifting mechanism 20 is located inside the housing 26. Specifically, the arm lifting mechanism 20 is located inside the rear end of the housing 26. The upper end of the arm lifting mechanism 20 is located inside the protrusion 26a. Specifically, the screw shaft 29 and the upper end of the guide rail 31 are located inside the protrusion 26a. Furthermore, when the arm 12 is raised to its upper limit position, the upper of the two guide blocks 32 that engage with one guide rail 31 is located inside the protrusion 26a (see Figure 4).

[0036] Furthermore, as described above, the arm lifting mechanism 20 raises and lowers the arm 12 together with the lifting body 27 between the lower limit position of the arm 12 shown in Figure 3 and the upper limit position of the arm 12 shown in Figure 4. When the arm 12 is lowered to the lower limit position, the first arm portion 15 is positioned in approximately the same position as the protruding portion 26a of the housing 26 in the vertical direction, and the upper surface of the protruding portion 26a is positioned above the lower surface of the first arm portion 15. Also, when the arm 12 is lowered to the lower limit position, the base end of the first arm portion 15 is positioned in front of the protruding portion 26a.

[0037] In other words, when the arm 12 is lowered to its lowest position, the upper end of the arm lifting mechanism 20 (specifically, the upper end of the screw shaft 29 and the guide rail 31) located inside the protrusion 26a is positioned behind the base end of the first arm section 15. That is, when the arm 12 is lowered to its lowest position, the upper end of the arm lifting mechanism 20 (specifically, the upper end of the screw shaft 29 and the guide rail 31) is positioned to the side of the base end of the first arm section 15. Also, when the arm 12 is lowered to its lowest position, the upper end of the arm lifting mechanism 20 (specifically, the upper end of the screw shaft 29 and the guide rail 31) is positioned above the lower surface of the first arm section 15.

[0038] Furthermore, when the arm 12 is lowered to its lowest position, the upper surface of the first arm portion 15 is positioned slightly above the upper surface of the protrusion 26a. Also, when the arm 12 is lowered to its lowest position, the lower surface of the second arm portion 16 is positioned above the upper surface of the protrusion 26a. In other words, when the arm 12 is lowered to its lowest position, the upper end of the arm lifting mechanism 20 is positioned below the lower end of the second arm portion 16.

[0039] In this embodiment, when the first arm portion 15 and the second arm portion 16 are positioned at a predetermined reference position relative to the main body portion 13 with the arms overlapping each other (as shown in Figures 2 to 4), the longitudinal directions of the first arm portion 15 and the second arm portion 16 coincide with the front-rear direction. Furthermore, when the first arm portion 15 and the second arm portion 16 are positioned at a reference position relative to the main body portion 13 with the arms overlapping each other and the arm 12 has been lowered to its lower limit position, the tip of the second arm portion 16 becomes the rear end of the second arm portion 16 and is positioned above the protruding portion 26a (see Figure 3).

[0040] In other words, when the first arm portion 15 and the second arm portion 16 are positioned at the reference position relative to the main body portion 13 with the arms overlapping each other and the arms 12 have been lowered to their lowest position, the tip of the second arm portion 16 is positioned above the arm lifting mechanism 20. Also, at this time, the base end of the first arm portion 15 is the rear end of the first arm portion 12 and is positioned in front of the upper end of the arm lifting mechanism 20. Furthermore, as shown in Figure 3, when the first arm portion 15 and the second arm portion 16 are positioned at the reference position relative to the main body portion 13 with the arms overlapping each other, the rear end of the second arm portion 16 is positioned in the front-rear direction at the same position as the rear end of the main body portion 13 (specifically, the rear surface of the housing 26).

[0041] In this embodiment, the front-to-back direction (Y direction) is the longitudinal direction of the arm portion when the first arm portion 15 and the second arm portion 16 are positioned at a reference position relative to the main body portion 13 with the arm portion overlapping each other. Furthermore, the rear side (Y2 direction side) is the first direction side, which is one side of the longitudinal direction of the arm portion, and the front side (Y1 direction side) is the second direction side, which is the opposite side of the first direction side.

[0042] The first arm drive mechanism 21 is equipped with a motor 39. The motor 39 is attached to the lifting body 27. The power of the motor 39 is transmitted to the first arm 15 by a power transmission mechanism consisting of a reduction gear, pulleys, and a belt. The second arm drive mechanism 22 is equipped with a motor 40. The motor 40 is attached to the connection between the first arm 15 and the lifting body 27. The power of the motor 40 is transmitted to the second arm 16 by a power transmission mechanism consisting of a reduction gear, pulleys, and a belt.

[0043] The third arm drive mechanism 23 includes a motor 41. The motor 41 is mounted inside the second arm 16. Power from the motor 41 is transmitted to the third arm 17 by a power transmission mechanism consisting of a reduction gear, pulleys, and a belt. The hand drive mechanism 24 includes a motor 42. The motor 42 is mounted inside the third arm 17. Power from the motor 42 is transmitted to the hand 11 by a power transmission mechanism consisting of a reduction gear, pulleys, and a belt.

[0044] Motors 39 to 42 are electrically connected to the control unit 38. In this embodiment, when the hand 11 moves in the left-right direction while its longitudinal direction coincides with the front-rear direction, the control unit 38 controls motors 39 to 42 so that the third rotation center C3 passes along a virtual line VL (see Figure 1) parallel to the left-right direction when viewed from above, thereby rotating the first arm section 15, the second arm section 16, the third arm section 17 and the hand 11.

[0045] In other words, when the hand 11 moves in the left-right direction while its longitudinal direction and front-rear direction coincide, the control unit 38 rotates the first arm section 15, the second arm section 16, the third arm section 17 and the hand 11 so that, when viewed from above, the third pivot center C3 moves linearly in the left-right direction. At this time, the control unit 38 rotates the first arm section 15, the second arm section 16, the third arm section 17 and the hand 11 so that the hand 11 and arm 12 do not interfere with the housing 8.

[0046] (Main effects of this form) As explained above, in this embodiment, when the arm 12 is lowered to its lowest position, the upper end of the arm lifting mechanism 20, which is located inside the protrusion 26a, is positioned behind the base end of the first arm portion 15. Therefore, in this embodiment, compared to the case where the entire arm lifting mechanism 20 is positioned below the first arm portion 15, it is possible to increase the height of the arm lifting mechanism 20 without changing the height of the robot 1 when the arm 12 is lowered to its lowest position. In other words, in this embodiment, it is possible to increase the vertical length of the screw shaft 29 and the guide rail 31 without changing the height of the robot 1 when the arm 12 is lowered to its lowest position. Consequently, in this embodiment, it is possible to increase the amount of lifting of the arm 12 without changing the height of the robot 1 when the arm 12 is lowered to its lowest position.

[0047] Furthermore, in this embodiment, the first distance D1, which is the horizontal distance between the first pivot center C1, which is the pivot center of the first arm portion 15 relative to the main body portion 13, and the second pivot center C2, which is the pivot center of the second arm portion 16 relative to the first arm portion 15, is shorter than the second distance D2, which is the horizontal distance between the third pivot center D3, which is the pivot center of the third arm portion 17 relative to the second arm portion 16, and the second pivot center D2. Thus, the length of the first arm portion 15 is shorter than the length of the second arm portion 16.

[0048] Therefore, in this embodiment, even if the upper end of the arm lifting mechanism 20 is positioned behind the base end of the first arm section 15 when the arm 12 is lowered to its lowest position, it becomes possible to position the upper end of the arm lifting mechanism 20 behind the shorter first arm section 15, and as a result, it becomes possible to miniaturize the robot 1 in the front-rear direction. In other words, in this embodiment, even if it is possible to increase the amount of lifting of the arm 12 without changing the height of the robot 1 when the arm 12 is lowered to its lowest position, it becomes possible to miniaturize the robot 1 in the front-rear direction.

[0049] Furthermore, in this embodiment, when the first arm portion 15 and the second arm portion 16 are positioned at a reference position relative to the main body portion 13 with the arms overlapping each other, the rear end of the second arm portion 16 is positioned at the same position as the rear end of the main body portion 13 in the front-rear direction. Therefore, even if the height of the robot 1 when the arm 12 is lowered to its lowest position is not changed, it is possible to increase the amount of lifting and lowering of the arm 12, while still making the robot 1 smaller in the front-rear direction.

[0050] In this embodiment, when the arm 12 is lowered to its lowest position, the lower surface of the second arm portion 16, which is the lower end of the second arm portion 16, is positioned above the upper surface of the protrusion 26a of the housing 26. Therefore, in this embodiment, even if there is no notch or the like formed on the second arm portion 16 to prevent interference between the protrusion 26a, which houses the upper end of the arm lifting mechanism 20, and the second arm portion 16, it is possible to prevent interference between the second arm portion 16 and the protrusion 26a when the second arm portion 16 rotates.

[0051] In this embodiment, the robot 1 includes a first arm drive mechanism 21 that rotates the first arm 15 relative to the main body 13, a second arm drive mechanism 22 that rotates the second arm 16 relative to the first arm 15, a third arm drive mechanism 23 that rotates the third arm 17 relative to the second arm 16, and a hand drive mechanism 24 that rotates the hand 11 relative to the third arm 17. Therefore, in this embodiment, it is possible to increase the degree of freedom of movement of the robot 1.

[0052] (Other embodiments) The above-described embodiments are examples of preferred embodiments of the present invention, but are not limited thereto, and various modifications can be made without altering the essence of the invention.

[0053] In the above-described configuration, when the first arm portion 15 and the second arm portion 16 are positioned relative to the main body portion 13 in a state where they overlap each other, the rear end of the second arm portion 16 may be positioned in front of the rear end of the main body portion 13, or it may be positioned behind the rear end of the main body portion 13. Also, in the above-described configuration, when the arm 12 is lowered to its lower limit position, the lower end of the second arm portion 16 may be positioned below the upper surface of the protruding portion 26a of the housing 26. In this case, a notch or the like is formed in the second arm portion 16 to prevent interference between the protruding portion 26a and the second arm portion 16.

[0054] In the above-described embodiment, the arm 12 may be composed of two arm sections: a first arm section 15 and a second arm section 16. In this case, the base end of the hand 11 is rotatably connected to the tip of the second arm section 16. In this case, the second distance, which is the horizontal distance between the third pivot center (the pivot center of the hand 11 relative to the second arm section 16) and the second pivot center C2, is longer than the first distance D1. Furthermore, in the above-described embodiment, the arm 12 may be composed of four or more arm sections.

[0055] In the above-described embodiment, the arm lifting mechanism 20 may, for example, include a guide shaft and a cylindrical guide bush through which the guide shaft is inserted, instead of the guide rail 31 and the guide block 32. Also, in the above-described embodiment, the arm lifting mechanism 20 may, for example, include a belt, partly fixed to the holding portion 27b of the lifting body 27, and a pulley over which this belt is stretched, instead of the ball screw 28. Furthermore, in the above-described embodiment, the number of hands 11 rotatably connected to the tip of the arm 12 may be one. Also, in the above-described embodiment, the object to be transported by the robot 1 may be something other than the wafer 2. In this case, for example, the object to be transported may be formed in the shape of a square or rectangular flat plate. [Explanation of symbols]

[0056] 1. Robot (horizontal articulated robot) 2. Wafer (semiconductor wafer, object to be transported) 11 Hand 12 arms 13 Main body 15. First Arm Section 16. Second Arm Section 17. Third Arm Section 20 Arm lifting mechanism 21 First Arm Drive Mechanism 22 Second Arm Drive Mechanism 23 Third Arm Drive Mechanism 24 Hand-driven mechanism 28 Ball screw 29 Screw shaft 31 Guide rails C1 First Movement Center C2 2nd Movement Center C3 3rd Movement Center D1 1st distance D2 2nd distance Y-arm section direction Y1 2nd direction side Y2 First direction side

Claims

1. In a horizontal articulated robot in which the arm moves horizontally, The system comprises a hand on which an object to be transported is mounted, an arm to which the hand is rotatably connected at its tip, a main body to which the base end of the arm is rotatably connected, and an arm lifting mechanism for raising and lowering the arm. The arm comprises a first arm portion whose base end is rotatably connected to the main body, and a second arm portion whose base end is rotatably connected to the tip end of the first arm portion. The lower side of the first arm is connected to the upper side of the main body, The lower side of the second arm is connected to the upper side of the first arm, The tip of the second arm portion is rotatably connected to the base end of the third arm portion, which constitutes a part of the arm, or to the base end of the hand. The first distance, which is the horizontal distance between the first pivot center, which is the pivot center of the first arm portion with respect to the main body, and the second pivot center, which is the pivot center of the second arm portion with respect to the first arm portion, is shorter than the second distance, which is the horizontal distance between the third pivot center, which is the pivot center of the third arm portion or the hand connected to the second arm portion with respect to the second arm portion, and the second pivot center. A horizontal articulated robot characterized in that, when the arm is lowered to its lowest position, the upper end of the arm lifting mechanism is positioned to the side of the base end of the first arm.

2. The arm lifting mechanism comprises a ball screw for raising and lowering the arm, and a guide rail for guiding the arm in the vertical direction. The screw shaft of the ball screw is positioned such that its axial direction and vertical direction coincide. The guide rails are arranged so that their longitudinal direction and vertical direction coincide. The horizontal articulated robot according to claim 1, characterized in that when the arm is lowered to its lower limit position, the screw shaft and the upper end of the guide rail are positioned to the side of the base end of the first arm.

3. The horizontal articulated robot according to claim 1 or 2, characterized in that when the arm is lowered to its lower limit position, the upper end of the arm lifting mechanism is positioned below the lower end of the second arm.

4. When the first arm portion and the second arm portion are positioned at a predetermined reference position relative to the main body portion with the arms overlapping each other, the longitudinal direction of the first arm portion and the longitudinal direction of the arms portion are defined as the first direction side, and the side opposite the first direction side is defined as the second direction side. A horizontal articulated robot according to any one of claims 1 to 3, characterized in that, when the first arm portion and the second arm portion are positioned at the reference position relative to the main body portion with the arms overlapping each other and when the arms are lowered to the lower limit position, the base end of the first arm portion is the end portion on the first direction side of the first arm portion and is positioned on the second direction side of the upper end portion of the arm lifting mechanism, and the tip portion of the second arm portion is the end portion on the first direction side of the second arm portion and is positioned above the arm lifting mechanism.

5. The lifting mechanism is housed inside the main body. The horizontal articulated robot according to claim 4, characterized in that when the first arm portion and the second arm portion are positioned relative to the main body portion at the reference position with respect to the main body portion in a state where they overlap each other, the first-direction side end of the second arm portion is positioned at the same position as the first-direction side end of the main body portion in the lateral direction of the arm length.

6. The base end of the third arm is rotatably connected to the tip end of the second arm, The horizontal articulated robot according to any one of claims 1 to 5, characterized in that the base end of the hand is rotatably connected to the tip end of the third arm.

7. The horizontal articulated robot according to claim 6, further comprising: a first arm drive mechanism for rotating the first arm relative to the main body; a second arm drive mechanism for rotating the second arm relative to the first arm; a third arm drive mechanism for rotating the third arm relative to the second arm; and a hand drive mechanism for rotating the hand relative to the third arm.

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