JP2003171081A - Ceiling transporting system and transporting method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of taking much time to load to a stocker during transporting between processes, in a conventional ceiling transporting system wherein a ceiling transporting vehicle with hoists is studied for moving articles when separate transporting devices are used for transporting within a process and transporting between the processes. <P>SOLUTION: This ceiling transporting system comprises a stocker 15 provided with a transfer device 21, a ceiling transporting vehicle 1 provided with a hoist 6, a handling device 16 wherein a cassette 5 is transferred by the hoist 6, and a rail 13 on which the ceiling transporting vehicle 1 travels. The ceiling transporting vehicle 1 is provided with a pair of falling-down preventive pieces 2b disposed under the cassette 5 and supporting the cassette 5. A clearance h1 allowing picking up of the cassette 5 by the transfer device 21 is provided between the cassette 5 supported by the falling-down preventive pieces 2b and an upper end of a supporting space 2a. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stocker provided with a scooping type transfer device, an overhead carrier provided with a hoist, and a processing device for transferring articles conveyed by the overhead carrier by the hoist. The present invention relates to a ceiling transfer system including a rail on which a ceiling transfer vehicle travels and a transfer method thereof.

[0002]

2. Description of the Related Art Conventionally, for an article such as a semiconductor which requires a large number of processing steps, a plurality of processing apparatuses are made into one system and a stocker is arranged for each system, and the article is conveyed between the systems. Transport and inter-process transport for transporting articles between one system stocker and another stocker are provided. For in-process transportation, a ceiling transportation vehicle with a hoist is used to transport the article to a predetermined height position of the processing device. Further, for the inter-process transportation, a ceiling transportation vehicle is used in which a scooping-up type transfer device is provided in the stocker so that only a mounting table is provided to enable high-speed transportation.

[0003]

If separate transport devices for in-process transport and inter-process transport are used, it is necessary to transfer articles between both transport systems. Therefore, all ceiling transport with hoist is required. It is being considered to use a car or a ceiling carrier equipped with a transfer device having a hoist at the tip. However, since the hoist requires a longer transfer time than the scooping-type transfer device, all the ceiling transfer vehicles with the hoist need a longer transfer time to the stocker during the inter-process transfer. Further, if the ceiling transfer vehicle is provided with the transfer device, a large strength is required for the ceiling transfer vehicle and its rails, which is difficult to implement. Therefore, the present invention provides an overhead transportation vehicle system and a transportation method thereof, which are provided with inter-process transportation and intra-process transportation, and which shorten transfer time as much as possible and do not require great strength for the ceiling transportation vehicle and rail. That is the challenge.

[0004]

The present invention uses the following means in order to solve the above problems. That is, in the invention of claim 1, in the ceiling transfer system, the stocker including the scooping-type transfer device, the ceiling transfer vehicle including the hoist, and the articles transferred by the ceiling transfer vehicle are transferred by the hoist. And a rail on which the ceiling carrier travels. The ceiling carrier is provided below the article to be transported, and can project horizontally from both sides of the article to support the article. A pair of fall prevention pieces are provided, and an interval is provided between the article supported by the fall prevention pieces and the upper end of the article storage space in the ceiling guided vehicle so that the transfer device can scoop the articles. There is something.

Further, in the invention of claim 2, the fall prevention piece is provided with a fall prevention portion and a support portion.

Further, in a third aspect of the present invention, in the method of transporting the ceiling transport system, at least a fall prevention piece capable of supporting an article provided in the ceiling transport vehicle from the stocker by the transfer device provided in the stocker. The step of transferring the article, the step of chucking the article supported by the fall prevention piece by the hoist provided on the ceiling transport vehicle, and the step of transporting the article while chucked by the hoist and lifted Or, a step of transferring the article chucked and lifted by the hoist to the fall prevention piece, and a step of transferring the article supported by the fall prevention piece to the stocker by the transfer device. Including.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the accompanying drawings. 1 is a plan view showing a ceiling transfer system, FIG. 2 is a side view showing a ceiling transfer vehicle, FIG. 3 is a side sectional view showing a lower end portion of a cassette placed on a fall prevention piece, and FIG.
Is a side view showing the ceiling transfer vehicle with the cassette placed on the fall prevention piece, FIG. 5 is a side view showing the ceiling transfer vehicle with the cassette being lifted by the stocker transfer device, and FIG. It is a side view which shows the ceiling conveyance vehicle in the state currently transferred to the processing apparatus by the hoist.

First, the overall configuration of the ceiling transfer system of the present invention will be described. A transfer system S shown in FIG. 1 is an application of the ceiling transfer system of the present invention to, for example, a transfer system for transferring a cassette for storing semiconductor wafers in a clean room of a semiconductor manufacturing factory.

In the transfer system S, rails 13 are laid on the ceiling of a clean room or the like, and a ceiling transfer vehicle 1 for transferring cassettes is configured to run along the rails 13. Around the rail 13, there are many stockers 15 for accommodating cassettes, a plurality of processing devices 16 for processing the wafers accommodated in the cassettes, and the like. A plurality of processing devices 16 are collectively arranged in a line for each process K1, K2, K3, K4 ... In the clean room.
A stocker 15 is arranged at the upstream end of 2.K3.K4 ....

The rail 13 is used for each process K1, K2, K
Stocker 15 and processing device 16 in 3.K4 ...
It is configured by an in-process rail 19 laid in the vicinity of and a inter-process rail 18 laid throughout the clean room. Inter-process rail 18 is used for each process K1 ・ K
2, K3, K4, etc. are connected to each other. For example, a process K1, K2, K3,
Another process from K4 ... K1, K2, K3, K4 ...
It is used when the cassette is transported to the. In-process rail 1
9 connects the stocker 15 and the processing devices 16 in each process K1, K2, K3, K4 ... And between the processing devices 16, for example, each process K1, K2, K3.
In K4 ..., from stocker 15 to processing device 16,
Alternatively, it is used when a cassette is transported from one processing device 16 to another processing device 16.

The ceiling carrier 1 traveling on the inter-process rail 18 and the ceiling carrier 1 traveling on the in-process rail 19 are configured to have the same specifications, and the inter-process rail 18 and the in-process rail 19 have a connecting path 20. The ceiling transport vehicle 1 running on the inter-process rail 18 and the ceiling transport vehicle 1 running on the in-process rail 19 are connected to each other by the inter-process rail 18 and the in-process rail 19 and the inter-process rail 18. There is.

Next, the ceiling carrier 1 will be described. The ceiling carrier 1 is composed of an article support unit 2 and a traveling device 3,
The traveling device 3 is supported by the rail 13 so as to be capable of traveling. The article support unit 2 has a support space 2a, and a hoist 6 having a chuck mechanism 7 is provided at the upper end of the support space 2a. In the support space 2a, the handle 5a is chucked by the chuck mechanism 7 and the cassette 5 supported by the hoist 6 is accommodated. In this way, the ceiling transport vehicle 1 is configured to transport the cassette 5 by traveling along the rail 13 while supporting and housing the cassette 5 in the support space 2a.

A pair of fall prevention pieces 2b, 2b are provided at the lower end of the article support portion 2. Fall prevention piece 2b
2b is an article support unit 2 which is arranged below the cassette 5 which is an article to be conveyed and which is located on both sides of the cassette 5.
It projects horizontally inward from both side walls. The dimension W1 between the fall prevention pieces 2b and 2b is the width dimension W2 of the cassette 5.
Is narrower than.

When the cassette 5 is carried by the ceiling carrier 1, as shown in FIG. 2, the cassette 5 is carried by the hoist 6 in the supporting space 2a and is lifted up. When the cassette 5 is dropped by releasing the chuck state by the mechanism 7, since the dimension W1 is configured to be smaller than the dimension W2, the cassette 5 is engaged with the fall prevention pieces 2b, 2b arranged below. It will stop and will remain in the support space 2a. In this way, by providing the article support portion 2 with the fall prevention pieces 2b, 2b, even if the chuck state by the chuck mechanism 7 is unexpectedly released, it is possible to prevent the cassette 5 from falling from the ceiling transport vehicle 1. You can

When the cassette 5 is lowered from the state shown in FIG. 2 supported by the hoist 6, the cassette 5 is placed on the upper surfaces of the fall prevention pieces 2b, 2b as shown in FIG. The cassette 5 can be supported by the fall prevention pieces 2b and 2b. In this case, the support protrusion 2c protruding upward is projected on the upper surface of the fall prevention piece 2b, and the support protrusion 2c is formed in the engagement groove formed on the bottom surface of the cassette 5 placed on the fall prevention piece 2b. 5b is engaged. By engaging the support protrusion 2c and the engagement groove 5b, the cassette 5 placed on the fall prevention piece 2b is positioned and supported.

By placing the cassette 5 on the fall prevention pieces 2b, 2b while engaging the support projection 2c with the engagement groove 5b, the article support section 2 repeatedly moves and stops, or shakes. Even if it is done, since the cassette 5 can be stably placed on the fall prevention pieces 2b and 2b,
In this state, the cassette 5 can be transported by the ceiling transport vehicle 1. In this way, mainly cassette 5
While mounting the cassette 5 on the fall prevention piece 2b that functions as a fall prevention member, the lower portion of the cassette 5 is supported by the support protrusions 2c that have the function of supporting the cassette 5, and thus the chuck mechanism of the hoist 6 is formed. As compared with the case where only the upper end portion of the cassette 5 is supported by 7, it is possible to suppress the shaking of the cassette 5, and it is possible to reliably convey the cassette 5 in a stable posture.

When the cassette 5 is placed on the fall prevention pieces 2b, 2b and conveyed, the grip portion 5a may or may not be chucked by the chuck mechanism 7. Further, the drop preventing pieces 2b, 2b, which are arranged below the conveyed cassette 5 and project horizontally inward from both side walls of the article support unit 2, are configured to have variable projecting amounts. That is, it is possible to adjust the dimension W1 between the fall prevention pieces 2b and 2b by changing the amount of protrusion from both side walls of the article support portion 2. Further, the shape of the support protrusion 2c is not limited to the protrusion formed in a substantially conical shape as in this example, but may be a pin member capable of engaging with the engagement groove 5b. Any device that can be engaged with and can position and support the cassette 5 may be used. Furthermore, the support protrusions 2c may have a plurality of shapes.

Here, in the present transport system S, a control device for controlling the operations of the ceiling transport vehicle 1, the stocker 15 and the like is provided, and by the control device, for example, the ceiling transport vehicle 1 is moved to the inter-process rail 18. The cassette 5 transported along the above is transferred to the stocker 15, the cassette 5 stored in the stocker 15 is transferred to the ceiling transport vehicle 1 traveling along the in-process rail 19, and the in-process rail 19 is further transferred. It is controlled to transfer the cassette 5 from the traveling overhead carrier 1 to the processing device 16.

When the cassette 5 is conveyed on the inter-process rail 18, it is in the state of being supported by the hoist 6 or being placed on the fall prevention pieces 2b, 2b as described above. When the cassette 5 is transferred from the ceiling carrier 1 traveling on the inter-process rail 18 to the stocker 15, the ceiling carrier 1 moves the cassette 5 onto the fall prevention pieces 2b and 2b as shown in FIG. While being placed, the chuck mechanism 7 is controlled to release the chucked state of the handle portion 5a. The operation of placing the cassette 5 on the fall prevention pieces 2b and 2b can be performed while the ceiling transport vehicle 1 is traveling, and is performed after the ceiling transport vehicle 1 is stopped in front of the stocker 15 to which the ceiling transport vehicle 1 is transferred. You can also Whether the transfer destination is the processing device 16 or the stocker 15 is determined by, for example,
The determination may be made based on the destination information included in the transfer command transmitted from the upper controller (not shown) to the ceiling transfer apparatus 1.

The stocker 15 is provided with a transfer device 21, and the transfer device 21 allows the fall prevention pieces 2b, 2b.
The cassette 5 placed on the top is transferred to the stocker 15. The transfer device 21 is configured as a scooping-type transfer device. After the transfer arm 21a of the transfer device 21 is moved to the lower side of the cassette 5, as shown in FIG.
1a is raised to raise the cassette 5, and the cassette 5 is taken out from the article supporting unit 2. Therefore, when the cassette 5 is lifted by the transfer arm 21a between the upper end of the cassette 5 placed on the fall prevention pieces 2b and 2b and the chuck mechanism 7 in the support space 2a, the cassette 5 The upper end of the and the chuck mechanism 7 do not interfere,
In addition, the gap h1 is such that the lower end of the cassette 5 and the support protrusion 2c protruding from the fall prevention piece 2b do not interfere with each other.
Is provided.

The cassette 5 thus taken out from the article supporting unit 2 and transferred to the stocker 15 is then transferred to the ceiling carrier 1 which travels on the in-process rail 19.
Ceiling carrier 1 from this stocker 15 to the in-process rail 19
The transfer device 21 of the stocker 15 is also used for transferring the cassette 5 to the stocker 15.
Done by. In this case, the cassette 5 stored in the stocker 15 is the transfer arm 21a of the transfer device 21.
Are carried to the ceiling carrier 1 and placed on the fall prevention pieces 2b, 2b of the article support unit 2.

The cassette 5 transferred from the stocker 15 to the ceiling carrier 1 of the in-process rail 19 is further transferred to a predetermined processing device 16. As shown in FIG. 6, the ceiling transfer vehicle 1 supported by the rails 13 laid on the ceiling surface of the clean room has a cassette mounting of the processing device 16 whose height from the floor surface is set to a predetermined height. The hoist 6 is used to transfer the cassette 5 from the ceiling carrier 1 to the processing device 16 because the cassette 5 is located at a position considerably higher than the surface 16a.

That is, the processing device 16 for transferring the cassette 5
During traveling of the ceiling guided vehicle 1 or the processing device 16
When the ceiling guided vehicle 1 travels up to this point, the cassette 5 is chucked by the chuck mechanism 7 and is supported by the hoist 6 as shown in FIG. From this state, the protrusion amount of the fall prevention pieces 2b, 2b is reduced so that the dimension W1 between the fall prevention pieces 2b, 2b becomes larger than the width dimension W2 of the cassette 5. The hoist 6 is configured to be able to move up and down by winding up or winding down the wire 6a. After that, the hoist 6 is wound down to lower the cassette 5, and the cassette 5 is placed on the cassette mounting device of the processing device 16. It is transferred to the surface 16a.
In addition, the engaging protrusion 16b is aligned with the engaging groove 5b formed on the lower surface of the cassette 5 on the cassette mounting surface 16a.
Is projected, and the cassette 5 placed on the cassette placing surface 16a is positioned.

On the contrary, when the cassette 5 is transferred from the processing device 16 to the ceiling carrier 1, the hoist 6 is also used for transfer. That is, after the cassette 5 mounted on the cassette mounting surface 16a is chucked by the chuck mechanism 7 of the hoist 6 that has descended, the hoist 6 is rolled up to move the cassette 5 to the support space 2a of the article support unit 2. To raise. After that, the protrusion amount of the fall prevention pieces 2b, 2b is increased so that the dimension W1 between the fall prevention pieces 2b, 2b becomes smaller than the width dimension W2 of the cassette 5.

As described above, the hoist 6 which can be raised and lowered is provided on the ceiling carrier 1, and the cassette 5 supported by the hoist 6 is provided.
A fall prevention piece 2b capable of supporting the cassette 5 below
2b is provided, and an interval h1 is provided between the upper end of the cassette 5 placed on the fall prevention pieces 2b and 2b and the support space 2a so that the cassette 5 can be picked up by the transfer device 21 and taken out. By doing so, rail 1 in the process
Between the ceiling guided vehicle 1 traveling on 9 and the processing device 16,
The cassette 5 is transferred by the hoist 6, and the cassette 5 is placed on the fall prevention pieces 2b and 2b between the ceiling transport vehicle 1 traveling on the inter-process rail 18 and the stocker 15 so that the cassette 5 is transferred to the stocker 15. The cassette 5 can be transferred using the transfer device 21 provided.

Therefore, the transfer time can be shortened between the ceiling guided vehicle 1 and the processing device 16 as compared with the case where the hoist 6 is used to perform the transfer operation in all the ceiling guided vehicles 1. . Further, in the present system, since the scooping-up type transfer device 21 is provided in the stocker 15, it is not necessary to increase the strength of the ceiling carrier 1 and the rails 13 such as the inter-process rail 18 and the intra-process rail 19.

In particular, the transport control performed by the transport system S is performed by moving the cassette 5 from the stocker 15 to the ceiling transport vehicle 1.
The transfer device 21 of the stocker 15
From the stocker 15 to the fall prevention pieces 2b, 2 of the ceiling guided vehicle 1.
b, the step of transferring the cassette 5 and the fall prevention piece 2
b and 2b, a step of chucking and supporting the cassette 5 supported by the chuck mechanism 7 of the hoist 6 provided on the ceiling transport vehicle 1, and a state in which the cassette 5 is chucked and lifted by the chuck mechanism 7 (see FIG. 2). Since the transfer device 21 can transfer the cassette 5, the transfer time can be shortened, and the transfer capability can be improved. Has become. Conversely, from the ceiling carrier 1 to the stocker 1
When the cassette 5 is transferred to the cassette 5, the cassette 5 chucked and lifted by the chuck mechanism 7 of the hoist 6 is transferred to the fall prevention pieces 2b and 2b, and the cassette 5 is moved to the fall prevention pieces 2b and 2b. Since the cassette 5 in the supported state is transferred to the stocker 15 by the transfer device 21, unlike the case where the cassette 5 is always chucked and supported by the hoist 6, the stocker 15 is not supported. It is possible to transfer the cassette 5 by the transfer device 21 of and transfer time can be shortened,
It is possible to improve the carrying capacity.

The ceiling carrier 1 traveling on the inter-process rail 18 enters the intra-process rail 18 through the connecting path 20 without transferring the cassette 5 to the stocker 15 and uses the hoist 6 to transfer the cassette 5 to the cassette 5. It is also possible to transfer the data directly to the processing device 16. With this configuration,
Since it is not necessary to transfer the cassette 5 to the stocker 5, it is possible to shorten the transfer time and perform a quick transfer process. Also, the number of stockers 15 can be reduced.

In the present embodiment, depending on the destination, the hoist 6 chucks the cassette 5 for transportation or the hoist 6 supports the fall prevention pieces 2b, 2b for transportation. Regardless of the destination, all fall prevention pieces 2b
The cassette 5 may be supported by 2b to be transported. More specifically, when the cassette 5 is transferred by the transfer device 21 of the stocker 15, the hoist 6 is conveyed without being operated. In this case, the hoist 6 is wound up, and an interval h1 is formed between the cassette 5 and the hoist 6 so that the hoist 6 can be picked up by the transfer device 21.

If the transport destination is the processing device 16,
During transportation or after reaching the processing device 16, the hoist 6 is lowered by a predetermined amount, and the chuck mechanism 7 of the hoist 6 chucks the handle portion 5a of the cassette 5. Next, in order to make the fall prevention pieces 2b, 2b movable, the hoist 6 is raised. Then, the fall prevention piece 2b that is projected
2b is returned to a position where the cassette 5 can pass, the hoist 6 is lowered, and the cassette mounting surface 16 of the processing device 16 is lowered.
Place the cassette 5 on a. On the other hand, the transport destination is stocker 1
If it is 5, the hoist 6 is conveyed to the target stocker 15 without being operated, and the transfer device 21 of the stocker 15 is transferred.
Then, the cassette 5 is transferred to the stocker 15. When receiving and transporting the cassette 5 placed on the cassette placing surface 16a of the processing device 16, the hoist 6 of the ceiling guided vehicle 1 is lowered by a predetermined amount, and the handle portion 5a of the cassette 5 is moved to the chuck mechanism 7 of the hoist 6. Chuck with. Then, the hoist 6 is raised to project the fall prevention pieces 2b, 2b until the cassette 5 can be supported, and then the hoist 6 is lowered by a predetermined amount to move the cassette 5 to the fall prevention piece 2b.
The cassette 5 is placed on 2b, and the cassette 5 is transported to the intended destination.

Further, in this embodiment, the fall prevention piece 2b is provided.
The support projection 2c formed on 2b and the engagement groove 5b formed on the bottom of the cassette 5 are engaged with each other, but the engagement portion formed according to the shape of the bottom of the cassette 5. May be formed into the fall prevention pieces 2b and 2b, and the bottom portion of the cassette 5 and the engagement portion may be engaged with each other. As a result, the cassette 5 can be positioned and the movement of the cassette 5 in the horizontal direction can be restricted. Fall prevention piece 2b / 2
When the engaging portion is formed on b, the fall prevention pieces 2b, 2b
The protrusion amount of the cassette 5 can be changed, and the cassette 5 is dropped although the first protrusion position where the cassette 5 is engaged with the engagement portion of the fall prevention pieces 2b and 2b is not engaged with the engagement portion. If the cassette 5 is supported by the fall prevention pieces 2b and 2b, the second protrusion position is provided (the protrusion amount is smaller than the first protrusion position), and the cassette 5 is transferred with the first protrusion position. It is preferable to control the protrusion amount of the fall prevention pieces 2b and 2b so as to change to the second protrusion position when performing.

[0032]

Since the present invention is constructed as described above, it has the following effects. That is, as described in claim 1, a stocker provided with a scooping-type transfer device, an ceiling transport vehicle provided with a hoist, and a processing device in which an article transported by the ceiling transport vehicle is transferred by the hoist, And a rail on which the ceiling carrier travels, wherein the ceiling carrier is provided with a pair of fall prevention pieces that are arranged below the article to be conveyed, project from both sides of the article horizontally inward, and can support the article. Since an interval is provided between the article supported by the fall prevention piece and the upper end of the article storage space in the ceiling transport vehicle, there is provided an interval for picking up the article by the transfer device. The hoist transfers the articles between the ceiling transport vehicle and the processing device, and the cassette is placed on the fall prevention piece between the ceiling transport vehicle and the stocker traveling on the inter-process rail. , Su It is possible to transfer the cassette with the transfer device provided in Tsu mosquitoes. Therefore, the transfer time can be shortened between the ceiling guided vehicle and the processing device, compared to the case where the transfer work is performed by hoists in all the ceiling guided vehicles. Further, in the present transport system, since the scooping-up type transfer device is provided in the stocker, it is not necessary to increase the strength of the ceiling transport vehicle and the rails such as the inter-process rail and the intra-process rail.

Further, as described in claim 2, since the fall prevention piece is provided with the fall prevention portion and the support portion, the article is placed on the fall prevention portion while the support portion lowers the article. By supporting, compared to the case where only the upper end of the article is supported by the chuck mechanism of the hoist, even when the ceiling carrier repeatedly moves and stops, or shakes, it is possible to suppress the shaking of the article, By means of the ceiling transport vehicle, it becomes possible to reliably transport the article in a stable posture.

Further, according to a third aspect of the present invention, in the carrying method of the present carrying system, at least the transfer device provided in the stocker moves from the stocker to the fall prevention piece provided on the ceiling carrier and capable of supporting the article. , A step of transferring the article, and a step of chucking the article supported by the fall prevention piece by a hoist provided on the ceiling carrier,
A step of chucking the article by a hoist and carrying it in a lifted state, or a step of transferring the article chucked and lifted by the hoist to the fall prevention piece, and supporting the fall prevention piece. And the step of transferring the article to the stocker by the transfer apparatus, unlike the case where the article is always chucked and supported by the hoist, the article is transferred by the scooping-type transfer apparatus of the stocker. Can be transferred, the transfer time can be shortened, and the transfer capacity can be improved.

[Brief description of drawings]

FIG. 1 is a plan view showing a ceiling transfer system.

FIG. 2 is a side view showing a ceiling carrier.

FIG. 3 is a side sectional view showing a lower end portion of the cassette placed on the fall prevention piece.

FIG. 4 is a side view showing the ceiling guided vehicle with the cassette placed on the fall prevention piece.

FIG. 5 is a side view showing the ceiling transport vehicle with the cassette being lifted by the stocker transfer device.

FIG. 6 is a side view showing the ceiling guided vehicle in a state where the cassette is transferred to the processing device by a hoist.

[Explanation of symbols]

1 Ceiling carrier 2 Article support 2b Fall prevention piece 2c Support protrusion 5 cassettes 6 hoists 7 Chuck mechanism 13 rails 15 Stocker 16 Processor 18 inter-process rail 19 Process rail

Claims (3)

[Claims] 1. A stocker provided with a scooping-type transfer device, a ceiling transfer vehicle provided with a hoist, a processing device for transferring articles transferred by the ceiling transfer vehicle by the hoist, and a ceiling transfer vehicle. The ceiling carrier is provided with a pair of fall prevention pieces which are arranged below the article to be conveyed, project from both sides of the article inward in the horizontal direction, and can support the article. The ceiling transfer system, wherein an interval is provided between the article supported by the prevention piece and the upper end of the article storage space in the ceiling transfer vehicle so that the transfer device can pick up the article. 2. The ceiling transfer system according to claim 1, wherein the fall prevention piece is provided with a fall prevention portion and a support portion. 3. A step of transferring the article from the stocker to a fall prevention piece provided on a ceiling carrier capable of supporting the article by at least a transfer device provided on the stocker, and supporting the fall prevention piece. A step of chucking the article with a hoist provided on the ceiling transport vehicle, and a step of transporting the article in a state of being chucked by the hoist and lifted, or, an article in a state of being chucked and lifted by the hoist. A transfer method of the ceiling transfer system, comprising: transferring onto the fall prevention piece; and transferring an article supported by the fall prevention piece onto the stocker by the transfer device.