JP2001233450A - Lateral conveying mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lateral conveying mechanism with a simple structure capable of conveying an object to be conveyed in an atmosphere isolated from atmospheric air. SOLUTION: This mechanism is provided with a loop-liked movable endless belt 12 driven by a driving device, a chamber 20 arranged on a surface side of the belt, at least two gap parts G arranged along with the circumference of the belt, and a seal member 18 holding on the gap parts G for the chamber as a space isolated from the atmospheric air side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal transport mechanism for transporting an object to be transported in a horizontal (horizontal) direction, and more particularly to, for example, a vacuum space separated from a normal atmospheric space via an endless transport belt. The present invention relates to a transport mechanism that can transport an object.

[0002]

2. Description of the Related Art A belt conveyor is a typical example of an apparatus for transporting an object to be transported in a horizontal (horizontal) direction. In the belt conveyor, by driving the drive shaft provided at both ends of the endless flat belt by a motor or the like,
The flat belt is moved in the horizontal direction to convey the object.

[0003] However, such a transport mechanism using a flat belt is used in the atmosphere. For example, in order to use the belt conveyor in a clean atmosphere such as a clean room or in a vacuum, the belt conveyer itself is used in a clean atmosphere such as a clean room. Alternatively, it is necessary to use it stored in a vacuum container. However, when such a belt conveyor itself is disposed in a clean atmosphere such as a clean room or in a vacuum container, there is a problem such as generation of dust from a driving mechanism between a motor and a pulley belt, and it is not always easy to maintain cleanliness. . In addition, the motor could not be installed under vacuum due to dust generation of the motor itself.

For example, in a manufacturing process of a semiconductor device, there is a manufacturing apparatus which performs processing under vacuum such as sputtering, CVD, etching, and ashing, and employs a cluster structure. In an apparatus having a cluster structure, as shown in FIG. 10, a robot 1 for handling a semiconductor wafer as an object to be processed is arranged at the center, and a plurality of processing chambers 2 are arranged around the robot 1 via gate valves. In the apparatus having such a cluster structure, a plurality of processes can be continuously performed, and when the process is shifted from one process to the next process, the substrate is not separately exposed to the outside air under a vacuum environment substantially equal to that of the processing chamber. The transfer can be performed between the processing chambers 2 by the robot 1.

However, the robot 1 fixed at the center
When a substrate is taken in and out of a large number of processing chambers on a table, the number of required processing chambers 2 increases, the number of clusters increases, the apparatus becomes large, and a robot having a long reach is required. . When two cluster-structured apparatuses are connected as shown in FIG. 11, the number of processing chambers 2 increases, but two robots 1 are required, and a transfer chamber 3 is required. There is a problem in that it becomes redundant and the assembly structure becomes complicated.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a horizontal transport mechanism capable of transporting a transported object in an atmosphere isolated from the atmosphere with a simple mechanism. With the goal.

[0007]

According to a first aspect of the present invention, there is provided an endless belt which is driven by a driving device and which is loopable and movable, a chamber provided on a surface side of the belt, and At least two located along the entire circumference of the belt
A horizontal transport mechanism comprising: two gaps; and a seal member held in the gaps, which spaces the chamber from the back side of the belt.

Since the gap between the belt and the at least two fixing portions is sealed by the sealing member, a chamber is formed on the front surface side of the belt, so that the chamber can be in an environment isolated from the atmosphere. . Therefore, by providing such a seal portion over the entire circumference of the belt in the transport direction, for example, the portion of the driving device on the back surface side of the belt can be set to the atmosphere side, and the front surface side of the belt can be set to a space separated from the atmosphere side. . Therefore, it is possible to arbitrarily move an object to be conveyed on the belt by moving the belt in the conveying direction, and thereby, the indoor environment including the surface side of the belt isolated from the atmosphere side despite the movement of the belt. Can be maintained.

According to a second aspect of the present invention, the belt includes a device fixedly penetrating through the belt, and a guide rail for supporting the device movably in a moving direction of the belt. It is what it was. Thus, for example, even when the equipment is heavy, such as a robot, it can be moved in a horizontal (horizontal) direction in an environment isolated from the atmosphere.

According to a third aspect of the present invention, the fluid seal member is provided by a soft material or a magnet having a high magnetic permeability disposed over the entire circumference in the moving direction of both ends of the belt, and a gap in the vicinity thereof. A magnetic flux path is formed by a magnet between the fixed-side yoke or the magnet, and the magnetic fluid seal member is held by the magnetic flux. Thereby, the back side of the belt is set to the atmosphere side, and the front side of the belt is separated from the atmosphere side.

According to a fourth aspect of the present invention, the endless belt is made of a soft sheet, and magnets are installed on both front and back sides of the soft sheet via a gap along the peripheral surface of the endless belt, An airtight holding mechanism for holding a magnetic fluid in at least one of the gaps between the magnet on the front and back sides and the soft sheet is provided. Thereby, by arranging magnets on both sides of the soft sheet, a magnetic flux penetrating the soft sheet is formed between the two magnets. By holding the magnetic fluid seal with this magnetic flux, a non-magnetic material (a material having a low magnetic permeability) can be used as the soft sheet. Therefore, it is possible to use a generally used flexible sheet such as a rubber material as the soft sheet.

According to a fifth aspect of the present invention, the first magnet and the second magnet are continuously arranged so that a part of the first magnet and the second magnet are shifted so as to overlap with each other. The magnetic fluid is held by the magnetic flux formed from the magnet or the second magnet, and in the overlapping portion,
The magnetic fluid is held by the magnetic flux formed by the first magnet and the second magnet, whereby the magnetic flux formed by the first magnet is continuously converted into the magnetic flux formed by the second magnet. The magnetic fluid is connected and continuously held along the moving direction of the belt. This makes it possible to easily form a solid magnetic fluid seal portion over the entire circumference of the belt by combining the small piece magnets. Further, the length of the magnetic fluid holding portion on the fixed side can be arbitrarily adjusted.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 shows a horizontal transport mechanism according to a first embodiment of the present invention.

An endless flat transport belt 12 is provided in the vacuum vessel 11, and the drive shaft 14 is driven to rotate by a motor (not shown) so that the belt 12 moves in the horizontal direction.
The other shaft 15 on which the belt 12 runs is a driven shaft, and conveys the article 13 by moving the belt. The surface side of the belt 12 faces the space 20 inside the container 11, and the magnetic fluid 1 is inserted into the gap G between the belt 12 and the fixing portion 11a.
The seal 8 is provided to form a space 20 isolated from the atmosphere. On the other hand, the back side of the belt 12 is a space that communicates with the atmosphere. In this embodiment, the chamber 20 isolated from the atmosphere is a clean atmosphere space, and this transport device transports the transported object 13 according to the traveling of the belt 12 under the clean atmosphere. The space 2 below the endless belt 12
1a communicates with the left and right ends of the container 11 as shown in FIG.

As shown in FIG. 1B, a soft magnet (rubber magnet) or a soft magnetic material 16 is disposed at both ends of the surface of the belt. The permanent magnet 17 or the permanent magnet 17 and the yoke are arranged on the fixing portion 11a of the facing container 11, and the soft magnetic body 16 is arranged close to the magnet, and the magnetic fluid 18 is held between the magnets. Is sealed. According to such a transport device, since the belt drive mechanism exists on the atmosphere side, the closed spaces 20, 20a
Has an advantage that the cleanliness can be easily secured. In addition, the belt 12 can travel without contact between the belt 12 and the fixing portion 11a of the container 11, so that there is no problem of generation of particles due to the contact, and therefore, the internal closed spaces 20, 20a of the container 11 are highly purified. The atmosphere can be kept.

FIG. 2 is a diagram showing a configuration example of the magnetic fluid seal portion. The magnetic flux emitted from the N pole of the permanent magnet 17 returns to the S pole of the permanent magnet 17 again from the yoke, the gap G, the soft magnetic material 16 on the belt, the gap G, and the yoke. Then, the magnetic fluid 18 is held in the gap, thereby forming a magnetic fluid seal portion. In this example, a total of four stages of magnetic fluid seals are formed by two permanent magnets in the widthwise direction of the belt. The number of stages of the magnetic fluid seal needs to be appropriately selected according to the required pressure and the like. Further, the yoke is not always necessary. For example, the magnet 17 may be arranged with a polarity as shown in FIG. 2B, and the magnetic fluid 18 may be held between the tip of the magnet 17 and the soft magnetic body 16. .

In this embodiment, the space inside the container 11 is a clean atmosphere space isolated from the atmosphere. However, a vacuum space can be easily formed by the following method. That is, since the motor as the drive source generally needs to radiate heat and cannot be used in a vacuum, it must be installed on the atmosphere side. By using a commercially available rotary magnetic fluid seal for the shaft seal portion to the motor and the belt transport mechanism, the differential pressure between atmospheric pressure and vacuum is maintained here. Thereby, both the inside and the outside of the belt are sealed in the container 11, and this space can be evacuated. By providing a balance pipe and installing a filter in the middle to substantially eliminate the differential pressure, the same degree of vacuum can be maintained while maintaining a clean atmosphere inside and outside the belt.

Here, the magnetic fluid is a colloidal liquid in which ferromagnetic metal fine particles are stably dispersed in a base solution. Therefore, this liquid is absorbed by the magnetic force of the magnet,
For example, it is used for vacuum sealing of a rotating shaft. In other words, by disposing a sleeve made of a magnetic material on the rotating shaft and disposing a permanent magnet and its yoke on the fixed side around it with a slight gap, the magnetic fluid completely blocks this gap. It works as if it were a ring-shaped liquid packing. The magnetic fluid is held by the magnetic force of the magnet, does not flow out even if there is a pressure difference between the vacuum side and the atmosphere side, can be vacuum sealed, and is widely used in vacuum equipment having a rotating part. ing.

FIG. 3 shows a horizontal transport mechanism under vacuum according to a second embodiment of the present invention. This horizontal transport mechanism moves a heavy robot, which is an equipment, in a vacuum chamber isolated from the atmosphere in a lateral direction. The lower part of the robot 1 penetrates the belt 23, and the guide rail 25
Movably supported. Therefore, robot 1
Is supported by the guide rail 25, and can move along the guide rail. At the lower part of the robot 1, there is a connecting portion 2 with the timing belt 23.
When the timing belt 23 is rotated by the driving of the motor 28 of the drive shaft 27, the robot 1 moves on the guide rails 25.

Also in this embodiment, both ends of the timing belt 23 are sealed with a magnetic fluid 29, and the surface side of the timing belt 23 is in a vacuum atmosphere of a clean atmosphere in the container 22. Vacuum atmosphere space 3 where particles are generated on the back side (inside)
1. The space 31 is a space in the vacuum vessel, and a pressure difference between the atmospheric pressure and the vacuum is maintained by the shaft seal portion 27a of the motor 28. Therefore, the upper space 30 in which the robot hand 1a exists and the lower space 30c of the loop-shaped lower timing belt 23 communicate with both ends in the container 22 as shown in FIG. It is a clean vacuum space. Here, the vacuum spaces 30, 31
Are communicated via a balance pipe P, and are kept at the same degree of vacuum. The filter F is for preventing particles from flowing from the space 31 where the particles exist to the clean space 30.

In the lower part of the robot, the belt penetrating part is shown in FIG.
As shown in (b), it is sealed by the O-ring 5. Accordingly, as the robot 1 travels along the belt 23, the robot hand unit 1a moves in the vacuum chamber 30, receives an object to be transferred in, for example, a certain processing chamber, and travels by the belt 23 to the front of another processing chamber. An object can be transferred from one processing chamber to another processing chamber. Note that, in this embodiment, an example has been described in which the chambers 30 and 31 which are isolated from the atmosphere are set in a vacuum atmosphere. However, it is needless to say that a high-purity air atmosphere or an inert gas atmosphere may be used.

FIGS. 4A and 4B show an example of a semiconductor manufacturing apparatus having a cluster structure using such a horizontal transport mechanism.
FIG. 4A shows a configuration in which the cluster is expanded in the longitudinal direction, and the robot 1 can be moved in the longitudinal direction in a direction indicated by an arrow in the figure while maintaining a vacuum state. This makes it possible to manufacture a small-sized and compact semiconductor manufacturing apparatus having a cluster structure including a large number of processing chambers 34 as a whole. FIG. 4B shows a case of a semiconductor manufacturing apparatus having a cluster structure in which three robots that can move in a horizontal direction while maintaining a vacuum state in a rectangular transfer chamber 35 are arranged. The processing chambers 34 are arranged around the transfer chambers 35, respectively, so that a semiconductor substrate as an object to be processed can be transferred between a large number of processing chambers 34 without providing a transfer chamber. Thereby, the installation space as a whole does not become large, and the functional transfer chamber 35 can be configured.

FIG. 5 shows another embodiment of the horizontal transport mechanism. This shows a case where the conventional cluster manufacturing semiconductor manufacturing apparatuses are connected by the horizontal transport mechanism of the present invention. As the lateral transport mechanism, the apparatus according to the first embodiment of the present invention shown in FIG. 1 is suitable. That is, the horizontal transport mechanism 36 uses the belt 12 hermetically sealed by a magnetic fluid seal to pass the semiconductor substrate or the cassette 40 or the like accommodating the substrate through a vacuum chamber isolated from the atmosphere and to the existing cluster structure semiconductor. It is moved between the manufacturing devices 37A and 37B. An operation example of this device will be described below.

For example, a semiconductor manufacturing apparatus 3 having a cluster structure
The cassette 40 containing the semiconductor wafers processed in 7A is placed on the belt 12 of the transfer mechanism 36 by the transfer device 38. The belt 1 is driven by rotating the motor.
2 is moved in the horizontal direction, whereby the cassette 40 placed on the belt 12 also moves to the front of the semiconductor manufacturing apparatus 37B having a cluster structure. Then, while maintaining the vacuum atmosphere by the transfer device 38 of the manufacturing apparatus 37B, the manufacturing apparatus 37
B is taken in. Then, the wafer is transferred to the processing chamber 34 by the robot of the manufacturing apparatus 37B, where predetermined processing is performed. After the end of the predetermined processing, the robot is taken out again by the robot in the manufacturing device 37B, placed on the belt 12 of the transport mechanism 36 via the transfer device 38, and moved to the front of the manufacturing device 37A by the movement of the belt 12. . Then, it is transferred to the load lock chamber 34L by the robot of the manufacturing device 37A via the transfer device 38 and taken out. By providing the horizontal transport mechanism of the present invention in this manner, two cluster-structured semiconductor manufacturing apparatuses 37A and 37B can be connected and used under a common vacuum atmosphere.

FIG. 6A is a plan view showing an arrangement of magnets for holding the magnetic fluid seal of the above embodiment. The fixed magnet holding the magnetic fluid seal is an endless belt 1
Since the magnets are arranged over the entire circumference, the magnets become long if they are made of an integral magnet, and their manufacture becomes difficult. As shown in FIG. 6 (a), the first magnet 42A and the second magnet 4
2B are alternately shifted from each other, and are continuously arranged along the moving direction of the endless belt. That is, the magnet 42A having the same magnetic pole (S-pole) is arranged on one side, and the second magnet 42B having the magnetic pole (N-pole) to which this magnetic pole is attracted is shifted in the longitudinal direction so that a part thereof is attracted to each other. Arrange continuously in the form. A yoke 4 is provided on the magnetic pole surfaces of the magnets 42A and 42B.
3 are provided, thereby forming a magnetic flux path.

FIGS. 6 (b), 6 (c) and 6 (d) show cross sections along line BB, CC and DD, respectively, in FIG. 6 (a). A magnetic flux φ is formed from the magnets 42A, 42B via a yoke 43, and the magnetic fluid 45
It is held in the gap between the belt 3 and the belt 12. Here, it is preferable to use a soft magnetic material having high magnetic permeability for the belt 12. Therefore, a part of the first magnet 42A and the second magnet 42B shown in FIG. 6A are overlapped, and are alternately and continuously arranged, so that the magnets are continuously arranged along the entire circumference of the belt. A magnetic fluid can be held. That is, the magnetic flux emitted from the portion where the first magnet 42A exists alone (the BB line portion) is formed from the N pole to the S pole of the magnet 42A,
The magnetic fluid 45 is inserted into the gap between the yoke 43 on the south pole side and the belt 12.
Hold. In a portion where the first magnet 42A and the second magnet 42B are attracted and present (CC line portion), the magnet 42A
Along with the magnetic flux from the N pole to the S pole of the magnet 42B and the magnetic flux from the N pole to the S pole of the magnet 42B.
A magnetic flux directed toward the south pole of 2A is formed, and the yoke on the south pole of the magnet 42A, the yoke on the north pole of the magnet 42B, and the belt 1
The magnetic fluid 45 is held in the gap 2. Second magnet 42B
Is present alone (DD line portion), a magnetic flux from the N pole to the S pole of the magnet 42B is formed, and the magnetic fluid 45 is held in the gap between the yoke 43 on the N pole side and the belt 12. In this way, the magnetic flux formed from the S pole side yoke of the magnet 42A and the magnetic flux formed from the N pole side yoke of the magnet 42B are continuously connected along the belt moving direction. This makes it possible to form a long continuous (solid) magnetic fluid seal along the belt moving direction by combining a large number of small piece magnets. Note that a plate 44 made of a non-magnetic material may be arranged between the tips of the yokes 43 arranged on the magnetic pole sides of the magnets 42a and 42B.
This can prevent the magnetic fluid 45 from flowing toward the magnet.

FIG. 6E shows two magnets 42A and 42C.
2 shows the configuration of the magnetic fluid seal portion in which the components are arranged in parallel. By arranging a plurality of magnets in parallel in this manner, a plurality of stages of sealing can be achieved, and in the case shown in the figure, a two-stage sealing is possible.

Further, in the above-described embodiment, an example in which magnets are arranged on the front side or the side of the belt has been described. However, magnets are provided on both sides of the front and back surfaces of the belt as shown in FIG. You may do it. In this case, it is better to use a non-magnetic material, that is, ordinary rubber, for the belt material because the flow of the magnetic flux is not alienated.

In the above-described embodiment, the example in which the magnetic flux is formed using the yoke in contact with the magnetic pole portion of the magnet has been described. However, the magnetic flux formed by the magnet is used without using the yoke. It may be. FIGS. 7A and 7B
FIG. 6C shows an example in which the yoke 43 is removed from the arrangement of the magnets in FIG. 6A and the magnet has a partially convex shape. Similarly, FIGS. 8A, 8B, and 8C show FIGS.
And the N pole and the S pole are arranged on the belt 12 side and the opposite side. Also in this case, by arranging the small-piece magnets continuously so that a part thereof overlaps, a continuous magnetic flux can be formed along the entire circumference of the belt. FIGS. 9 (a), 9 (b), and 9 (c) show FIGS.
In the arrangement of the magnets in (a), the magnets are arranged such that the polarities of the magnets face each other. The magnet 4
The magnetic flux formed from 2A and the magnetic flux formed from magnet 42B are continuously connected along the moving direction of the belt, and a magnetic fluid seal along the entire circumference of the belt is enabled.

As described above, since the magnets 42A and 42B are divided into small pieces, it is possible to slide the magnetic fluid 45 while holding the magnetic fluid 45 at the magnetic pole portion at the tip of the yoke 43 by providing a slide mechanism. . This makes it possible to make the holding mechanism for the magnetic fluid on the fixed side extendable and contractable, and to form a magnetic fluid seal portion that can cope with belt elongation. Here, the soft magnetic body 44 provided on the belt side is formed by dispersing, for example, a ferrite-based magnetic material powder having a high magnetic permeability in rubber. By using such a material, even if the entire circumference of the belt becomes long, a magnetic fluid seal for isolating the belt from the atmosphere can be easily provided along the entire circumference of the belt.

In the above embodiment, an example has been described in which a permanent magnet is used to generate a magnetic flux for holding the magnetic fluid sealing material, but an electromagnet may be used. Further, the shapes and arrangements of these magnets are not limited to those shown in the drawings, and various shapes and structures can be adopted.
Further, in the above-described embodiment, an example in which the moving body is sealed using the magnetic fluid seal has been described, but any other type of fluid seal may be used as long as the material can perform an airtight seal that is isolated from the atmosphere. You may do it.

[0032]

As described above, according to the present invention, an object can be transported in a room isolated from the atmosphere by hermetically sealing the end of the endless belt with a fluid seal member. .

[Brief description of the drawings]

FIG. 1 shows a horizontal transport mechanism according to a first embodiment of the present invention.
(A) It is a front view, (b) is sectional drawing which followed the BB line.

FIG. 2 is a diagram illustrating a configuration example of a magnetic fluid seal unit in FIG. 1;

FIG. 3 shows a horizontal transport mechanism according to a second embodiment of the present invention.
(A) It is a longitudinal cross-sectional view along a conveyance direction, (b) is a vertical cross-section along the surface orthogonal to a conveyance direction, (c) It is a top view.

FIG. 4 (a) using the horizontal transport mechanism of the second embodiment.
It is a figure which shows the Example of the semiconductor manufacturing apparatus which expanded the cluster structure, and is a figure which shows the example of a structure of the semiconductor manufacturing apparatus which has a transfer room provided with the robot which can move three laterally (b).

FIG. 5 is a diagram showing an example of connecting existing semiconductor manufacturing apparatuses having a cluster structure using the horizontal transport mechanism of the present invention.

FIG. 6 is a diagram showing a configuration example of a magnetic fluid seal;
(A) It is a top view which shows the example of arrangement | positioning of the magnet and yoke comprised by arrange | positioning some magnets of a small piece so that it may overlap,
(B) is an enlarged sectional view along line BB of (a),
(C) is an enlarged sectional view along the CC line, and (d) is a D
It is an expanded sectional view which met the D line, (e) is a top view showing the example of arrangement of the magnet and the yoke which arranged the magnet in two rows and parallel and performed the two-step seal, and (f) is the front and back of the belt. It is an expanded sectional view at the time of arrange | positioning so that a magnetic fluid seal may be pinched on both sides.

FIG. 7 is a diagram corresponding to FIGS. 6A, 6B, and 6C;
A case is shown in which a partly convex magnet is used without using a yoke.

FIG. 8 is a diagram corresponding to FIGS. 6 (a), (b), and (c);
The case where the arrangement of the magnetic poles of the magnet is changed without using the yoke is shown.

9 (a) is a BB line when the magnets shown in FIG. 6 (a) are arranged so as to partially overlap each other so that the same poles face each other.
It is sectional drawing along (b) CC line and (c) DD line.

FIG. 10 is a diagram illustrating a configuration example of a conventional semiconductor manufacturing apparatus having a cluster structure.

FIG. 11 is a diagram showing a configuration example in a case where two conventional semiconductor manufacturing apparatuses having a cluster structure are connected and used.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Robot 1a Robot hand 11,22 Vacuum container 11a Magnet holding part 12,23 Belt 13 Conveyed object 14,27 Drive shaft 15 Follower shaft 18,29 Magnetic fluid 20,30 Vacuum space 24 Slider 25 Guide rail 26 Connecting part 28 Motor

Claims (5)

[Claims] 1. A loop-shaped and movable endless belt driven by a driving device, a chamber provided on a surface side of the belt, and at least two belts arranged along the entire circumference of the belt in the chamber. A horizontal transport mechanism comprising: a gap; and a seal member held in the gap, the chamber being a space isolated from the back side of the belt. 2. The belt according to claim 1, further comprising: a device penetrating through the belt and fixed to the belt; and a guide rail for movably supporting the device in a moving direction of the belt. Item 2. The horizontal transport mechanism according to Item 1. 3. The sealing member includes a soft material or a magnet having a high magnetic permeability disposed over the entire length in the longitudinal direction at both ends in the short direction of the belt, and a fixed side disposed via a gap in the vicinity thereof. 3. A magnetic flux path is formed by a magnet between the yoke or the magnet and the magnetic fluid sealing member is held by the magnetic flux.
2. The horizontal transport mechanism according to 1. 4. The endless belt is made of a soft sheet, and magnets are installed on both front and back sides of the soft sheet via a gap along the peripheral surface of the endless belt, and the front and back sides of the soft sheet are 2. The horizontal transport mechanism according to claim 1, further comprising an airtight holding mechanism that holds a magnetic fluid in at least one of a gap between the magnet and the soft sheet. 5. A first magnet and a second magnet are continuously arranged so that a part thereof is shifted so as to overlap with each other, and the first magnet and the second magnet are formed from the first magnet or the second magnet in a non-overlapping part. The magnetic fluid is held by the magnetic flux generated, and in the overlapping portion, the magnetic fluid is held by the magnetic flux formed by the first magnet and the second magnet, whereby the magnetic fluid is formed by the first magnet. The horizontal magnetic field according to claim 1, wherein the magnetic flux is continuously connected to the magnetic flux formed by the second magnet, and the magnetic fluid is continuously held along the moving direction of the belt. Transport mechanism.