Patent Description:
A stacker crane for transferring an article is used in an automated storage and a facility such as an intrabay in which processing machine is arranged (One example is described in the following <CIT>). The stacker crane includes, for example, a traveling carriage traveling along a track provided on a floor surface of a facility, a mast extending upward from the traveling carriage, an elevating platform moving along the mast, and a transfer device provided on the elevating platform. Such a stacker crane is capable of moving the entire stacker crane by a carriage drive unit of the traveling carriage. The longer the mast is, or the larger the acceleration of the traveling carriage is, the stress and moment applied to the connecting part between the mast and the traveling carriage become larger. As a result, the higher rigidity is required for the mast, and the weight of the mast becomes heavier.

The stacker crane of <CIT> includes travelling carriages (vehicles) at the upper and lower positions. The mast is swingably attached to each of the upper and lower traveling carriages. Additionally, the mast is attached to one of the traveling carriages so as to freely shift in the vertical direction. In such a stacker crane, the stress and moment applied to the connecting part between the mast and the traveling carriage can be reduced. As a result, the weight of the stacker crane of <CIT> decreases.

<CIT> shows a stacker crane according to the preamble of claim <NUM>. <CIT> shows a stacker crane comprising: a carriage drive unit; a traveling carriage traveling along a track attached to a vertical wall; an elevating platform mounted on the carriage so as to move up and down together with the carriage; a transfer unit which is provided on the elevating platform and transfers an article; at least one stopper for stopping the traveling carriage; a switching unit for switching a state of the traveling carriage between a fixed state and a released state by the stopper; wherein the switching unit controls the stopper to release the fixation of the stopper and enables the traveling carriage to follow the track in the traveling direction when the carriage drive unit drives the traveling carriage, and the switching unit controls the stopper to fix the traveling carriage when the carriage drive unit stops the traveling carriage.

The stacker crane of <CIT> enables to reduce the weight of the mast, however it requires two traveling carriages such as at least one upper and one lower traveling carriage. As a track such as a rail is required for the lower traveling carriage traveling on the floor surface, it is necessary to lay a large number of rails on the floor surface in the facility, and an increase in cost is incurred. As the mast is attached swingably with respect to the traveling carriage, the position of the mast relative to the transfer destination of the article may be displaced. Thus, the position of the elevating platform is deviated from the transfer destination. As a result, it is difficult to transfer the article to a target position.

In response to the above issue, it is an object of the present invention to provide a stacker crane which prevents an increase in facility cost while reducing the weight of the mast and transfers an article to a target position.

The invention provides a stacker crane according to claim <NUM>.

The masts may be provided on the both sides of the elevating platform in the traveling direction of the traveling carriage. The stacker crane may include a lower support base connected to the lower end of each of the masts. The stoppers may be provided on the lower support base. The stoppers may move back and forth so as to come into contact with or separate from the floor surface.

The stacker crane may also be provided with a guide roller for guiding the traveling carriage along a rail formed on a floor surface of a part of the track at the lower part of each of the masts. The elevating platform may further include a mast guide moving up and down along the mast. In an example of the stacker crane, the transfer unit transfers the article in the direction perpendicular and horizontal to the traveling direction of the traveling carriage. The rigidity of the masts in both vertical and horizontal directions to the traveling direction of the traveling carriage is preferably higher than that of the masts in the traveling direction of the traveling carriage. Further, a suppressor may be provided to reduce and control the oscillation or vibration of the mast.

In the stacker crane according to the present invention, as the mast is suspended from the traveling carriage, the weight of the mast can be reduced. As a result, a guide rail need not be installed on the floor within the facility and the facility cost can be reduced. When the article is transferred, the stoppers fix the mast. That allows the stacker crane to transfer the article to a target position while the elevating platform and the transfer unit are stopped at the predetermined positions. The stacker crane includes a plurality of masts and stoppers.

In the embodiment, the stacker crane includes the masts on the front and rear sides of the elevating platform in the traveling direction of the traveling carriage, the lower support base connected to the lower end of each of the masts, and the stoppers on the lower support base. The stoppers of this embodiment can easily fix the plurality of masts at the lower part via the lower support base. The stoppers may further be configured to advance and retreat so as to contact with or separate from the floor surface. By the stoppers, the switching unit can easily switch a state of the mast between a fixed state and a released state. In the invention, the detector is provided for detecting a deviation of the actual stop position of the lower part of each of the masts fixed by the stoppers from the predetermined target stop position. The detector can easily detect the deviation of the lower part of each of the masts from the target stop position. Further, the calibrator is provided for adjusting the deviation detected by the detector. This calibrator can adjust the deviation of the lower part of each of the masts, thus the stacker crane of this example enables the deviation of the actual transfer position from the target transfer position easily to be adjusted.

In the preferred embodiment, guide rollers are provided at the lower part of each of the masts for guiding the traveling carriage to the guide rail formed on the floor surface of the section where the traveling carriage travels. As the traveling carriage is guided by the rail, the lower part of each of the masts is prevented from largely deviating from a position below the traveling carriage when traveling on a curve. As a further preferable example, the elevating platform may be provided with mast guides to move up and down along the mast. The mast guides allow the elevating platform to move up and down smoothly. As the transfer unit transfers the article in the direction perpendicular and horizontal to the traveling direction of the traveling carriage, the mast preferably has higher rigidity in the horizontal direction than in the traveling direction. Such mast can support a force generated in the horizontal direction and prevent the transfer direction of the article from deviating from the target position when the article is transferred. The stacker crane may further include a suppressor for suppressing the oscillation or vibration of the mast to prevent the vibration from being transmitted to the article.

Preferred embodiments of the present invention will be described hereinafter with reference to the drawings. In each of the following figures, a direction is described by using a Cartesian XYZ coordinate system. In this XYZ coordinate system, a vertical direction is indicated as the Z direction, and a horizontal direction is indicated as the X direction and the Y direction. With respect to each of the X, Y and Z directions, a direction indicated by an arrow is expressed as + direction (for example, the +X direction) and the opposite direction is expressed as the -X direction (for example, the -X direction).

<FIG> is a diagram showing a transport system to which a stacker crane according to an embodiment of the present invention is applied. Such a transport system 1A is installed in a semiconductor device fabrication plant and applied to a system which transports a FOUP (Front Opening Unified Pod) containing semiconductor wafers used for semiconductor device manufacture or an article <NUM> such as a reticle pod containing processing components such as a reticle. Here, the article <NUM> is described as a FOUP, but not limited to this. The transport system 1A is applicable to facilities except for the semiconductor field, and the article <NUM> may be a variety of articles handled in the facility where the transport system 1A is installed.

The transport system 1A includes a stacker crane <NUM> and a track <NUM>. In an example of the preferred embodiment, the track <NUM> is a traveling rail and is suspended from a ceiling <NUM> of the facility with a plurality of rail support members 5a. The stacker crane <NUM> travels along the track <NUM> and transfers the article <NUM> to the transfer destination. For example, the transfer destination or transfer origin of the article <NUM> includes, but is not limited to, a load port 32a of a processing machine <NUM> (shown in <FIG>), a storage shelf <NUM> arranged in a stocker (automated storage) or on the processing machine (shown later in <FIG>), or a buffer.

The processing machine includes, for example, an exposure machine, a coater developer, a film forming device, or an etching device and applies various kinds of processing to the semiconductor wafer housed in the article <NUM>. The stocker stores the article <NUM> transported by the transport system 1A. The buffer includes a side track buffer (STB) or an under track buffer (UTB) which are installed near the processing machine. An overhead traveling vehicle of the transport system 1A (not shown) temporarily stores the article <NUM> in the buffer. The overhead traveling vehicle includes, for example, an OHT (Overhead Hoist Transport) or an OHV (Overhead Hoist Vehicle).

The stacker crane <NUM> includes a traveling carriage <NUM>, mast <NUM>, an elevating platform <NUM>, a transfer unit <NUM> and stoppers <NUM>. The traveling carriage <NUM> travels along the track <NUM>. The traveling direction of the traveling carriage <NUM> is the direction substantially parallel to the track <NUM> (the X direction in <FIG>). The traveling carriage <NUM> includes, for example, a carriage drive unit 11a such as an electric motor, driving wheels 11b, driven wheels 11c, a decelerator (not shown) and an encoder (not shown). The driving wheels 11b are attached so as to be pressed against an inside upper surface of the track <NUM> by an elastic member (not shown) such as a spring and connected to the output shaft of the electric motor (carriage drive unit 11a) through the decelerator. The rotation of the output shaft of the electric motor is transmitted through the decelerator to the driving wheels 11b, and then the traveling carriage <NUM> travels by the rotation of the driving wheels 11b. A caster is attached to each driven wheel 11c so as to be rotatable around the caster axis in the vertical direction (the Z direction) and also be in contact with the inner bottom surface of the track <NUM>. The encoder detects the rotation frequency of the output shaft of the electric motor and outputs the detection results to a controller (not shown). The controller controls the rotation frequency of the electric motor based on the results of the encoder and determines the speed and the stop position of the traveling carriage <NUM>. The stop position of the traveling carriage <NUM> may be set by detecting an index plate installed in advance along the track <NUM>. Besides the electric motor, a linear motor may be used as the carriage drive unit 11a.

The stacker crane <NUM> includes a rotary shaft <NUM> provided below the traveling carriage <NUM> and an upper support base <NUM> attached to the lower part of the rotary shaft <NUM>. The masts <NUM> are attached to the upper support base <NUM> and suspended from the traveling carriage <NUM>. The masts <NUM> are provided on both sides (a +X direction <a plus X-direction>, a -X direction <a minus X-direction>) of the traveling direction of the traveling carriage <NUM> (the X direction). The masts <NUM> may be attached to the upper support base <NUM>, for example, with a fastening member such as a bolt and nut or by welding.

The masts <NUM> are connected to a lower support base <NUM> at their lower ends. The lower support base <NUM> is connected to a + X-side mast <NUM> and - X-side mast <NUM> so that the distance between each of the masts at the lower support base <NUM> is equal to the distance between each of the masts at the upper support base <NUM>. Thus the distance between both of the masts <NUM> is equal or substantially equal at both upper and lower ends. The lower support base <NUM> has, for example, a plate shape. The front and rear masts <NUM> are connected to the front and rear parts of the elevating platform <NUM> in the traveling direction of the traveling carriage. The elevating platform <NUM> will be described later in detail. The lower support base <NUM> having stoppers <NUM> which are configured to move back and forth so as to contact with or separate from the floor surface <NUM>. The stoppers <NUM> will be described later in detail.

When the traveling carriage <NUM> accelerates in the traveling direction (for example, when the traveling carriage starts to travel from a stop state), the lower part of each of the masts <NUM> cannot follow the lower part of the traveling carriage <NUM> due to an inertia force, which causes a delay. The delay of the lower part of each of the masts <NUM> can be solved by the following method. For example, the carriage drive unit 11a temporarily decelerates the traveling carriage <NUM> or repeats to decelerate the traveling carriage <NUM> several times during acceleration or traveling.

When the traveling carriage <NUM> decelerates toward the traveling direction (for example, when the traveling carriage stops from a traveling state), the lower part of each of the masts <NUM> moves ahead of the lower part of the traveling carriage <NUM> due to an inertia force. This problem is caused by moving the lower part of each of the masts <NUM> ahead. The carriage drive unit 11a can solve this problem by temporarily increasing the acceleration of the traveling carriage <NUM> or repeating such an increase in the acceleration over a plurality of times before or during slowing down to stop the traveling carriage <NUM>.

In this embodiment, the stacker crane <NUM> includes a suppressor <NUM> for reducing the oscillation or vibration of the mast <NUM>. <FIG> is a diagram showing an example of the suppressor <NUM>. As <FIG> shows, the suppressor <NUM> such as an air damper or an oil damper, applies a force to the mast in the direction (indicated by the arrow F) opposite to the movement of the mast <NUM> (indicated by the arrow D). For another example, the suppressor <NUM> includes, but is not limited to, an elastic member such as a coil spring or a mechanism such as an actuator for imparting a force to the mast <NUM>.

Returning to the description of <FIG>, the elevating platform <NUM> moves up and down along the masts <NUM>. The elevating platform <NUM> is placed between the +X side mast <NUM> and the -X side mast <NUM>. The elevating platform <NUM> is suspended from the upper support base <NUM> with hoist cables (not shown) such as wires. The upper support base <NUM> is provided with an elevating drive unit <NUM> for winding up and down the hoist cables. The elevating drive unit <NUM> winds the hoist cables down and then the elevating platform <NUM> is guided to descend along the masts <NUM>. The elevating drive unit <NUM> winds the hoist cable up and then the elevating platform <NUM> is guided to ascend along the masts <NUM>. The transfer unit <NUM> is provided on the elevating platform <NUM>.

<FIG> shows an example of the masts <NUM>, the mast guides <NUM>, and the mast guides <NUM>. <FIG> is a diagram in which the mast guide <NUM> and a pair of the mast guides <NUM> are applied to the masts <NUM> having square cross section. <FIG> is a diagram in which the mast guide <NUM> and a pair of the mast guides <NUM> are applied to the masts 12a having rectangle cross section to increase the rigidity in the transfer direction. The transfer unit <NUM> includes an arm <NUM> and a holder <NUM>. The arm <NUM> includes an arm 25a and an arm 25b that are linked to each other with a joint 25c. The arm <NUM> expands and contracts in the horizontal direction which is the Y direction by folding the arm 25a and the arm 25b at the joint 25c. The arm <NUM> is connected to the elevating platform <NUM> at the proximal end and to the holder <NUM> at the distal end. The holder <NUM> has a plurality of (for example, three) pins <NUM> (for example, kinematic pins). The pins <NUM> respectively enter into a plurality of radial grooves formed on the bottom surface of the article <NUM>. In this way, the pins <NUM> determine an accurate position of the article <NUM> on the holder <NUM>.

The transfer unit <NUM> extends the arm <NUM> towards the direction of the transfer origin and places the holder <NUM> under the bottom of the article <NUM> and then receives the article <NUM> from the transfer origin. The elevating platform <NUM> moves up, and then the transfer unit <NUM> scoops up the article <NUM> with the holder <NUM>. The transfer unit <NUM> contracts the arm <NUM> while holding the article <NUM> on the holder <NUM> and then places the holder <NUM> on the elevating platform <NUM>. The following describes how the transfer unit <NUM> transfers the article <NUM> to the transfer destination. The transfer unit <NUM> determines a position toward the transfer destination and extends the arm <NUM> and places the article <NUM> on the holder <NUM> above the transfer destination. The elevating platform <NUM> moves down, and then the transfer unit <NUM> transfers the article <NUM> from the holder <NUM> to the transfer destination.

The transfer unit <NUM> shown in <FIG> is one example and may have other structures. For example, the transfer unit may hold the article <NUM> by firmly gripping a flange which is placed on the upper part of the article <NUM> or by holding the sides of the article <NUM>. The transfer unit <NUM> may include, but is not limited to the arm <NUM>. For example, an articulated robotics arm may be used.

A direction which the article <NUM> moves to when the transfer unit <NUM> transfers the article <NUM> is hereinafter referred to as a transfer direction accordingly. In this description, the expression "transfer direction" means a direction that the arm <NUM> extends and contracts to/from (the Y direction) and also a direction perpendicular and horizontal to the traveling direction of the traveling carriage <NUM> (the X direction). As shown in <FIG>, the elevating platform <NUM> incudes the mast guides <NUM> and the mast guides <NUM> for guiding the elevating platform <NUM> along the masts <NUM>. Each of the mast guides <NUM> and the mast guides <NUM>, for example, includes a guide roller.

The elevating platform <NUM> includes the mast guides <NUM> on its upper surface. Each of the mast guides <NUM> guides the +X side mast <NUM> and the -X side mast <NUM> in the traveling direction of the traveling carriage. The mast guides <NUM> regulate the moving path of the elevating platform <NUM> and the masts <NUM> in the X direction. Moreover, the mast guides <NUM> regulate each position of the masts <NUM> on the +X side and the -X side with respect to the elevating platform <NUM>. The mast guides <NUM> then determine the relative position of each of the masts <NUM> on the +X and - X sides in the X direction.

The mast guides <NUM> are arranged so as to pinch each of the masts <NUM> on the +Y and -Y sides from the perpendicular direction and the horizontal direction (the transfer direction) to the traveling direction of the traveling carriage <NUM>. The mast guide enables elevating platform <NUM> smoothly to move up and down. This allows the mast guide <NUM> to prevent interference between the mast <NUM> and the elevating platform <NUM>. The mast guides <NUM> also prevent the elevating platform <NUM> from shifting to the transfer direction from the positions of the masts <NUM> and detaching from the moving path along each of the masts <NUM>. In the preferred example, the mast guides <NUM> may preferably pinch each of the +X side mast <NUM> and the -X side mast <NUM> from both sides. The mast guides <NUM> and the mast guides <NUM> prevent the elevating platform <NUM> from deviating from the moving path along each of the masts <NUM> as the mast guide <NUM> and a pair of the mast guides <NUM> surround each of the masts <NUM>.

A mast 12a in <FIG> and the mast <NUM> in <FIG> have different shape. The mast 12a has a higher rigidity in the direction perpendicular to the traveling direction of the traveling carriage <NUM> and the horizontal direction (the transfer direction, the Y direction) than in the traveling direction of the traveling carriage <NUM> (the X direction). Here, the rigidity in the transfer direction is the rigidity to a bending moment around an axis parallel to the X direction. The rigidity in the traveling direction is the rigidity to the bending moment around an axis parallel to the Y direction. In <FIG>, the dimension of the mast <NUM> in the Y direction is longer than that in the X direction, and the rigidity in the transfer direction is higher than that in the traveling direction.

The holder <NUM> holds the article <NUM> and the arm <NUM> is extended, and then the transfer unit <NUM> receives a moment around an axis parallel to the X direction. The moment is transmitted to the mast <NUM> via the elevating platform <NUM>. As shown in <FIG>, as the mast 12a in the embodiment has the higher rigidity in the transfer direction than in the traveling direction, the weight of the mast 12a can be lightened by reducing the rigidity in the traveling direction, and the rigidity in the transfer direction enables the mast 12a to withstand the bending moment generated at the time of transferring the article.

Returning to the description of <FIG>, the weight of the stacker crane <NUM> supported by the ceiling is larger than the weight supported by the floor <NUM>, when the traveling carriage <NUM> travels. For example, the stacker crane <NUM> is not in contact with the floor <NUM> (in a state of being lifted from the floor <NUM>) when the traveling carriage <NUM> travels. The total weight of the stacker crane <NUM> is supported by the track <NUM> and the weight supported by the floor surface <NUM> is approximately zero. In the embodiment, the carriage drive unit <NUM> disposed at the upper side of the upper support unit including the upper support base <NUM> (for example, the carriage drive unit 11a) mainly supplies a driving force for the traveling carriage <NUM> to travel. As the lower support unit including the lower support base <NUM> is not provided with the carriage drive unit for providing the driving force, the lower support base <NUM> moves by following the upper support base <NUM>.

The stoppers <NUM> fix the masts <NUM> to a stationary object. The stationary object includes, for example, the floor surface <NUM>, the storage shelf <NUM> (such as the stocker or the buffer) or the processing machine <NUM>. In this embodiment, the stoppers <NUM> fix the masts to the floor <NUM>, and then the transfer unit <NUM> transfers the article. The stoppers <NUM> include anchors on the lower support base <NUM> at the both sides of the traveling direction (the X direction). The stoppers <NUM> are capable of advancing or retreating (ascending or descending) above the floor surface <NUM>. The stacker crane <NUM> also includes the switching unit <NUM> for switching the state of the mast between a fixed state and a released state. The switching unit <NUM> is attached on the lower support base <NUM>, for example. Having a stopper driver (for example, electric motor or cylinder device), the switching unit <NUM> is capable of switching between the fixed state and the released state by moving forward or backward the stoppers <NUM> by the stopper driver. The stoppers <NUM> may fix the masts <NUM> when parking the traveling carriage <NUM>.

When the carriage drive unit 11a drives the traveling carriage <NUM>, the switching unit <NUM> controls the stoppers <NUM> to release the fixation of the stoppers and enables the lower part of each of the masts to follow the upper part of each of the masts <NUM> in the travelling direction. When the carriage drive unit 11a stops the traveling carriage <NUM>, the switching unit <NUM> can control the stoppers <NUM> to fix the masts <NUM> (lower part of each of the masts <NUM>) after the lower part of each of the masts <NUM> stops following the upper part of each of the masts <NUM> (after a predetermined time has passed from the stop of the traveling carriage <NUM>) or immediately after the traveling carriage <NUM> stops. The stoppers <NUM> fix the masts <NUM> (lower support base <NUM>) and then the relative position between the transfer destination and the elevating platform <NUM> is determined. The fixing of the masts <NUM> by the stoppers <NUM> is the preparation for position adjustment with respect to the transfer destination of the article <NUM>, which will be explained later.

When the transfer unit <NUM> transfers the article, the switching unit <NUM> enables the stoppers <NUM> to advance to the floor <NUM> and contact with the floor surface <NUM> to fix the lower support base <NUM> to the floor surface <NUM>. The masts <NUM> are fixed to the floor <NUM> together with the lower support base <NUM> by the stoppers <NUM> as the lower end of each of the masts <NUM> is connected to the lower support base <NUM>. Thus, the lower part of each of the masts <NUM> and the lower support base <NUM> are fixed to the stationary object (such as the floor surface <NUM>).

<FIG> shows one example of a transfer operation of the article <NUM>, <FIG> shows a state in which the article is in the process of being transferred to the load port, and <FIG> shows a diagram in which the article has reached the load port. The transport system 1A of this embodiment includes a storage shelf <NUM> for storing the article <NUM>. The storage shelves <NUM> are aligned, for example, in the X direction with respect to the processing machine <NUM>. The storage shelf <NUM> has a plurality of shelf plates 31a arranged in the vertical direction. The transfer unit <NUM> of the stacker crane <NUM> can receive and deliver the article <NUM> from/to each of the plurality of the shelf plates 31a.

The switching unit <NUM> moves the stoppers <NUM> downward to contact with the floor surface <NUM> and fix the lower support base <NUM> and the lower part of each of the masts <NUM> to the floor <NUM>, and the transfer unit <NUM> transfers the article <NUM> to the shelf plate 31a (in the fixed state). In addition, the switching unit <NUM> causes the stoppers <NUM> to fix the lower support base <NUM> and the lower part of each of the masts <NUM> to the floor <NUM>, the transfer unit <NUM> receives the article <NUM> from the shelf plate 31a (in the fixed state). The transport system 1A may not include the storage shelf <NUM>, and transfer the article <NUM> to some storage place other than the storage shelf <NUM>. After the article <NUM> has been transferred completely, the switching unit <NUM> moves the stoppers <NUM> upward and away from the floor surface <NUM>, and enables the traveling carriage <NUM> to travel freely (in the released state).

As shown in <FIG>, the lower support base <NUM> and the lower part of each of the masts <NUM> are fixed to the floor <NUM>, by the stoppers <NUM>, and then the transfer unit <NUM> approaches the transfer destination and transfers (or receives) the article <NUM> to (or from) the transfer destination. In addition, the transfer unit <NUM> may transfer the article <NUM> from/to the load port 32a of the processing machine <NUM> other than from/to the storage shelf <NUM>. For example, the transfer unit <NUM> receives the article <NUM> from the storage shelf <NUM> and transfers the article <NUM> to the load port 32a. The transfer unit <NUM> also receives the article <NUM> from the load port 32a and transfers the article <NUM> to the storage shelf <NUM>.

For example, the switching unit <NUM> moves the stoppers <NUM> downward to contact with the floor surface <NUM> and fix the lower support base <NUM> and the lower part of each of the masts <NUM> to the floor surface <NUM> in the same way as described above, and the transfer unit <NUM> transfers the article <NUM> from/to the load port 32a. In another example, the transfer unit <NUM> may transfer the article <NUM> from/to the stocker (automated storage) or the buffer (each of them not shown) as is the case with the load port 32a. The lower support base <NUM> and the lower part of each of the masts <NUM> are fixed to the floor surface <NUM> in a manner similar to that described above, and then the transfer unit <NUM> transfers the article <NUM> from/to the stocker.

<FIG> shows one example of the stoppers <NUM> and a detector <NUM>, <FIG> is a diagram viewed from the X direction, <FIG> is a diagram viewed in the Y direction, and <FIG> is a diagram viewed from the Z direction and showing a detection operation. The stoppers <NUM> as shown in <FIG> have outriggers <NUM> for elevating and lowering from/to a position of the lower support base <NUM> by the switching unit <NUM>. The outriggers <NUM> are brought into contact with the floor surface <NUM> to restrict the movement of the lower support base <NUM> in the horizontal direction and are movably attached to the lower support base <NUM>. The switching unit <NUM> advances and retreats the outriggers <NUM> from/to the floor surface <NUM>. The switching unit <NUM> is, for example, controlled by a controller of the stacker crane <NUM> (not shown). This controller manages to advance and retreat the outriggers <NUM> at the timing when the controller specifies. Note that, the structure of the stoppers <NUM> is not limited to the structure shown in <FIG> and other structures may be adopted.

Moreover, the stacker crane <NUM> may include the detector <NUM> as shown in <FIG>. A distance sensor may be used as an example of the detector <NUM>. In the above described drawings, the distance sensor is attached to the undersurface and also in a substantially center part of the lower support base <NUM> in the traveling direction via a stay 37a, but the detector <NUM> can be attached to any position. In addition, as shown in <FIG>, a mirror reflector <NUM> is placed at a position below the transfer destination of the article <NUM>. The mirror reflector <NUM> is disposed on a side surface of the processing machine <NUM> (refer to <FIG>) and also at a position below the load port 32a.

In this example, a light-emitting element of the detector <NUM> emits the light to be detected such as laser light to the mirror reflector <NUM>, the mirror reflector <NUM> reflects the light to be detected to the detector <NUM>, and then a light-receiving element of the detector <NUM> detects the reflected light. A distance calculation section of the detector <NUM> measures a distance between the detector <NUM> (lower support base <NUM>) and the mirror reflector <NUM>. The measured distance is compared with the target distance recorded in a memory of the controller (not shown) of the stacker crane <NUM> and then the deviation amount in the Y direction is calculated. A calibrator <NUM> adjusts the position deviating from the target position by the distance calculated by the detector <NUM> or the controller of the stacker crane <NUM>. The example of the transfer unit <NUM> used by the calibrator <NUM> is explained below.

In the embodiment, the stoppers <NUM> fix the lower support base <NUM> and the lower part of each of the masts <NUM> after the traveling carriage <NUM> stops at the target position. Such operation causes the lower support base <NUM> and the lower part of each of the masts <NUM> to deviate from the target stop position. As mentioned above, the deviation amount of the traveling direction (the X direction deviation) is caused by the lower part of each of the masts <NUM> and the lower support base <NUM>. Thus the deviation amount can be reduced by using a drive source, which controls the acceleration and deceleration of the traveling carriage <NUM> during traveling, when the traveling carriage slows down to stop. On the other hand, the deviation amount of the transfer direction (the Y direction deviation) cannot be reduced because of the lack of adjustment by such a drive source. The Y direction deviation is expected to be generated as the masts <NUM> are swinging in the transfer direction. This allows that the deviation amount from the target stop position is likely to be larger in the transfer direction (the Y direction) than in the traveling direction (the X direction).

The detector <NUM> detects a deviation in the transfer direction, and the detected deviation is adjusted by the calibrator <NUM>. This allows the article to be transferred to the accurate position. The calibrator <NUM> using the transfer unit <NUM> is explained as an example. The transfer unit <NUM> extends the arm <NUM> up to the predetermined distance (the stroke length) (shown in <FIG>). As mentioned above, since the deviation occurs in the transfer direction, the detector <NUM> detects the deviation amount and sends the detected deviation amount to a controller of the transfer unit <NUM>. The controller of the transfer unit <NUM> adjusts the stroke length according to the detected deviation amount. In this way, the calibrator <NUM> using the transfer unit <NUM> allows the article <NUM> to be accurately transferred to the transfer destination (for example, the storage shelf <NUM> in <FIG>).

In another example of the preferred embodiment, the detector <NUM> may measure not only the deviation amount in the transfer direction but also the deviation amount in the traveling direction. The detector <NUM> emits the light to be detected toward the mirror reflector <NUM> provided in the traveling direction and detects the light reflected by the mirror reflector <NUM>. The deviation amount in the traveling direction is calculated based on the information derived from the detected data. The detector <NUM> for measuring the deviation amount in this example is not limited to the distance sensor, but includes an image sensor mounted on the lower support base <NUM>. A mark indicating the position of the processing machine <NUM> may be provided on the floor <NUM>. The detector <NUM> measures the deviation in either one or both of the traveling and transfer direction to the target position by the image data captured by the image sensor.

In this example, the calibrator <NUM> is configured with a unit that is mounted on the lower support base <NUM> and moves the transfer unit <NUM> in both the X and Y directions. The combination of the two units enables the transfer unit <NUM> to move in both directions.

<FIG> shows one example where guide rollers <NUM> are applied to the stacker crane, <FIG> is a diagram viewed in the Z direction, and <FIG> is a diagram viewed in the Y direction. As shown in <FIG>, in the preferred embodiment of the present invention, a plurality of guide rollers <NUM> are provided on the undersurface of the lower support base <NUM>. Four guide rollers <NUM> are rotatable. The guide rollers <NUM> are held to one bracket 42a in pairs. The two brackets 42a are attached to the lower support base <NUM>. Each guide roller <NUM> is rotatable around an axis in the vertical direction (the Z direction) and is placed at a substantially same height as the other guide roller <NUM> and also at an interval so as to allow to interpose a guide rail <NUM> (mentioned later. ) The arrangement and the number of guide rollers <NUM> in the preferred embodiment are just one example and are not limited or restricted.

<FIG> shows one example using the guide rail <NUM>, <FIG> is a diagram illustrating the travel state of the stacker crane <NUM>, <FIG> shows a diagram viewed from the X direction, and <FIG> shows a diagram viewed in the Y direction. In the transport system of the preferred embodiment, the track <NUM> may include zones 4a and 4b. The zone 4a is curved and the zone 4b is linear. As shown in <FIG>, the guide rail <NUM> is installed along the curved zone 4a on the floor <NUM> but not along the linear zone 4b on the floor <NUM>. In this way, the guide rail <NUM> may be installed along a certain zone on the floor <NUM> under the track <NUM>.

In examples shown in <FIG>, the lower support base <NUM> includes the guide rollers <NUM> which are guided by the guide rail <NUM>. The guide rollers <NUM> are disposed to pinch the guide rail <NUM> in the transfer direction (the Y direction). Each guide roller <NUM> rotates in contact with the guide rail <NUM>. A friction force between the guide rollers <NUM> and the guide rail <NUM> is, for example, set to be as small as it can be ignored against the friction force which can support the weight of the stacker crane <NUM>, and the fact remains that a substantial amount of the total weight of the stacker crane <NUM> is still supported by the track <NUM>.

When the stacker crane <NUM> travels along the curved zone 4a, the centrifugal force is applied to the masts <NUM> in outward direction of the curve, which is perpendicular and horizontal to the traveling direction while the stacker crane <NUM> travels along the curve zone 4a. Such centrifugal force acts on the masts <NUM> as the bending moment in the transfer direction (perpendicular direction to the traveling direction and also horizontal direction). As shown in <FIG>, the guide rollers <NUM> guide the stacker crane <NUM> along the guide rail <NUM>. At least a part of such centrifugal force acting on the guide rail <NUM> is received via the guide rollers <NUM>. As a result, the moment acting on the masts <NUM> can be reduced. In this embodiment, the weight of the stacker crane <NUM> becomes lighter as the rigidity required for the masts <NUM> or the connector between the masts <NUM> and the upper support base decreases.

In the embodiment, the linear zone 4b does not have the guide rail <NUM>. Since the stacker crane <NUM> does not come into contact with the floor <NUM>, the stacker crane <NUM> is fully supported by the track <NUM>. The stacker crane <NUM> may not come into contact with the floor <NUM> in all zones of the track <NUM> or a part of zones of the track <NUM> (zone 4b). The guide rail <NUM> may also be installed in the linear zone 4b as shown in <FIG>.

Additionally, <FIG> illustrates a structure where the guide rollers <NUM> guide the stacker crane <NUM> by rolling along the guide rail <NUM> which is installed on the floor <NUM>, but is not limited to this structure. For example, only a part of the masts <NUM> or the lower support base <NUM> connected to the lower ends of the masts <NUM> may be guided by the guide rail. Moreover, a guide member such as the guide rail <NUM> may be, for example, suspended from the ceiling <NUM> or provided on a part of the processing machine installed on the floor <NUM>, as well as being installed on the floor <NUM>.

<FIG> shows one example of the transport system 1B using the stacker crane 3A according to another embodiment. <FIG> is a diagram viewed in the Y direction, and <FIG> is a diagram viewed from the X direction. In the embodiment, the same reference signs are given to the components similar to that in the embodiment which is previously described. The explanation for the signs is omitted or simplified. Additionally, the switching unit <NUM> shown in <FIG> is not shown in <FIG>.

In the stacker crane 3A shown in <FIG>, the masts <NUM> and the upper support base <NUM> are connected by connectors <NUM>. Each of the connectors <NUM> is, for example, hinged and has an axis 18a (refer to <FIG>) in the perpendicular direction to the travel direction of the traveling carriage <NUM> (the X direction) and also in the horizontal direction (the Y direction). The connector <NUM> does not substantially transmit the moment around the axis 18a except for friction. The traveling carriage <NUM> supports the masts <NUM> with the connectors <NUM>, which are configured to be rotatable (freely rotatable) around the axes 18a.

In addition, the connectors <NUM> receive a moment around the axes 18a in two directions (the X direction, the Z direction) perpendicular to the axes 18a. The mechanism of the connectors <NUM> prevents the masts <NUM>, which are arranged in the mast longitudinal direction and the vertical direction (the Z direction), from inclining to the lateral side (the -Y direction or the +Y direction) of the track <NUM> and from being twisted around the vertical direction (the Z direction) when the traveling carriage <NUM> travels. The connector <NUM> is described as a hinge in the embodiment, but it is not limited to, which includes an universal joint having a mechanism for rotatating around a plurality of axes (for example, the X direction, the Y direction).

The lower end of each of the masts <NUM> and the lower support base <NUM> are connected by connectors <NUM>. Each of the connectors <NUM> is, for example, hinges and has an axis 19a (refer to <FIG>) in the perpendicular direction to the traveling direction of the traveling carriage <NUM> (the X direction) and also the horizontal direction (the Y direction). The connector <NUM> does not substantially transmit the moment around the axis 19a except for the influence of friction. The connectors <NUM> connect the lower support base <NUM> and the masts <NUM> so as to support the lower support base <NUM> and the masts <NUM> rotatable (freely rotatable) around the axes 19a.

In addition, the connector <NUM> receives the moment around two directions perpendicular to the axes 19a (the X direction, the Z direction), which is similar to the connector <NUM>. The connector <NUM> prevents the mast <NUM> from being twisted by the lower support base <NUM> around the vertical direction (the Z direction). The connector <NUM> is described as hinge in the embodiment, but it is not limited to, which includes an universal joint having a mechanism for rotatating around a plurality of axes (for example, the X direction, the Y direction).

In the stacker crane 3A shown in <FIG>, when the traveling carriage <NUM> accelerates or decelerates, the masts <NUM> are rotated and inclined by an inertia force on the lower support base <NUM> side. However, as the lower support base <NUM> is rotatable around the connector <NUM> of the mast <NUM>, the stacker crane 3A maintains the substantially horizontal state even in a state where the masts <NUM> are inclined. In view of the stacker crane 3A in the Y direction, a rectangular shape is formed by + X-side mast <NUM>, - X-side mast <NUM>, and upper and lower support base <NUM>, <NUM>. This shape changes from rectangular to parallelogram upon the acceleration and deceleration of the traveling carriage as the lower support base <NUM> moves in a time delay and moves ahead of a position below the upper support base <NUM>. However, the lower support base <NUM> can maintain the substantially horizontal state at the time of acceleration and deceleration.

The elevating platform <NUM> is, as shown in <FIG>, formed by connecting side and bottom plates via hinges 13a. Such hinges 13a rotatably connect the side and bottom plates of the elevating platform. The side plates enable the bottom plate of the elevating platform <NUM> to be horizontal by rotating along with the masts <NUM> when the masts <NUM> swing.

<FIG> is a diagram showing calibrators 39a according to another embodiment. In the <FIG>, the transfer unit <NUM> is adopted as the calibrator <NUM>, however the calibrators 39a shown in <FIG> may be used instead of the calibrator <NUM>. The calibrators 39a are, as shown in <FIG>, provided on the undersurface of the lower support base <NUM> and also on the both sides of the traveling direction (the X direction). The calibrators 39a include a X axis slider 40a that can move from the undersurface of the lower support base <NUM> to the X direction and a Y axis slider 40b that can move from the undersurface of the X axis slider 40a to the Y direction. The stopper <NUM> includes a support member 15a for supporting, advancing, and retreating the outrigger <NUM>. The Y axis slider 40b and the stopper <NUM> are connected by the support member 15a.

The X axis slider 40a moves to the X direction by an X axis drive unit (not shown). The Y axis slider 40b moves to the Y direction by a Y axis drive unit(not shown). The calibrator 39a drives the X axis drive unit (not shown) and the Y axis drive unit (not shown) according to the deviation amount of the X direction (traveling direction) and the Y direction (transfer direction) detected by the detector <NUM> (refer to <FIG>) to move the X axis slider 40a and the Y axis slider 40b, so that the relative position of the X direction (traveling direction) and the Y direction (transfer direction) toward the outrigger <NUM> can be adjusted via the support member 15a.

This allows the lower support base <NUM> to be repositioned to the target stop position by driving the calibrators 39a after being fixed by the stoppers <NUM>. The transfer unit <NUM> (refer to <FIG>) can be placed at the appropriate position by this adjustment to accurately transfer the article <NUM> to the transfer destination. The structure shown in <FIG> is an example of an optional mechanism used by the stoppers <NUM> movable to the X direction (traveling direction) and the Y direction (transfer direction).

In the embodiment of the stacker cranes <NUM> and the stacker crane 3A, the weight of the mast <NUM> can be lightened as the mast <NUM> is suspended from the traveling carriage <NUM>. Facility costs can also be reduced as a number of guide rails <NUM> are not required on the floor <NUM> within the facility. The stoppers <NUM> fix the lower part of each of the masts <NUM> to the stationary object (the floor <NUM>) while the article <NUM> is transferred. This enables the elevating platform <NUM> and the transfer unit <NUM> to be positioned accurately. Thus, the transfer unit <NUM> can transfer the article <NUM> to the target position.

Overhead hoist vehicles set on the transport systems 1A, 1B may use at least a part of the track <NUM> as a rail. In the preferred embodiments, the track <NUM> is provided on the ceiling <NUM> of the facility via the rail support members 5a. In another example, the track <NUM> may be provided directly on the ceiling <NUM> or, for example, on a frame (beam) formed near the ceiling <NUM>. As explained in the preferred embodiments of the transport systems, the stoppers <NUM> come into contact with the floor <NUM> and fix the masts <NUM> to the floor <NUM>. In another example, the stoppers <NUM> may come into contact with a structure fixed on the floor <NUM> or the stationary object such as various devices and fix the lower part of each of the masts <NUM> to the stationary object.

Claim 1:
A stacker crane (<NUM>; 3A) comprising:
a carriage drive unit (11a);
a traveling carriage (<NUM>) traveling along a track (<NUM>) attached to a ceiling (<NUM>) of a facility;
at least two masts (<NUM>, 12a) connected to a lower support base (<NUM>) at their lower end parts suspended from the traveling carriage (<NUM>);
an elevating platform (<NUM>) guided along the masts (<NUM>; 12a) so as to freely move up and down;
a transfer unit (<NUM>) which is provided on the elevating platform (<NUM>) and transfers an article (<NUM>);
stoppers (<NUM>) for fixing the masts (<NUM>; 12a) to a stationary object; and
a switching unit (<NUM>) for switching a state of the masts (<NUM>; 12a) between a fixed state and a released state by the stoppers (<NUM>);
wherein the switching unit (<NUM>) controls the stoppers (<NUM>) to release the fixation of the stoppers (<NUM>) and enables the lower part of each of the masts (<NUM>; 12a) to follow the upper part of each of the masts (<NUM>; 12a) in the traveling direction when the carriage drive unit (11a) drives the traveling carriage (<NUM>), and the switching unit (<NUM>) controls the stoppers (<NUM>) to fix the masts (<NUM>; 12a) when the carriage drive unit (11a) stops the traveling carriage (<NUM>),
characterized by
a detector (<NUM>) for detecting a deviation between a predetermined target stop position and an actual stop position of the lower part of each of the masts (<NUM>; 12a) upon the masts being fixed by the stoppers (<NUM>), and
a calibrator (<NUM>) for correcting the deviation detected by the detector (<NUM>),
wherein the calibrator (<NUM>) adjusts the stroke length of a transfer unit's arm according to the detected deviation amount in the horizontal direction perpendicular to the traveling direction of the traveling carriage (<NUM>) or, when the calibrator (<NUM>) is configured with a unit that is mounted on the lower support base (<NUM>), the calibrator (<NUM>) moves the transfer unit (<NUM>) in the traveling direction and in the horizontal direction perpendicular to the traveling direction of the traveling carriage (<NUM>).