JP2011162346A - Floatation conveyance device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely prevent damaging of a substrate W when the substrate W is transferred from a preceding floating unit 37 side to a subsequent floating unit 37 side by crossing over an insertion gap IG. <P>SOLUTION: An air suction apparatus 43 sucking air from a downward direction is disposed to a position near the upstream of the insertion gap IG. The air suction apparatus 43 locally gives the substrate W a downward force by a suction force of a suction fan 53 so that an upward force is generated on a tip side of the substrate W by using a central part of an air accumulation layer S as a fulcrum point, wherein the air accumulation layer S is generated between the floating unit 37 just upstream of the insertion gap IG and the substrate W. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a levitation conveyance apparatus that levitates and conveys a substrate such as a glass substrate in a conveyance direction.

  In recent years, various developments have been made on levitation conveyance devices in the field of clean conveyance, and the prior art of levitation conveyance devices is disclosed in Patent Document 1 (already filed by the applicant of the present application). And the structure of the levitating conveyance apparatus based on a prior art is as follows.

  That is, the levitation conveyance apparatus according to the prior art includes an apparatus frame, and the apparatus frame extends in the conveyance direction. The apparatus frame is provided with a transport mechanism for transporting the substrate in the transport direction.

  The apparatus frame is provided with a plurality of levitation units that levitate the substrate using the pressure of air as the levitation gas along the conveyance direction and the conveyance width direction orthogonal to the conveyance direction. The interior of each levitation unit is connected to an air supply source that supplies air as levitation gas, and a nozzle for ejecting air is formed on the upper surface of each levitation unit. An air reservoir layer (pressure reservoir layer) can be generated between the substrate and the substrate.

  Although not disclosed in Patent Document 1, normally, a substrate receiving member that transfers or receives substrates to and from a plurality of floating units is inserted between any floating units adjacent to each other in the transport direction. An insertion gap is formed (formed).

  Therefore, air is supplied to the inside of each floating unit by the air supply source, and air is ejected from the nozzles of each floating unit, and the transport mechanism is appropriately operated. Accordingly, the substrate can be levitated and conveyed (conveyed in a levitated state) in the conveyance direction while generating an air pool layer between the substrate and the plurality of levitation units.

JP 2006-182563 A

  By the way, a substrate such as a glass substrate is easy to bend, and when the substrate is transferred to the floating position, the tip of the substrate is transferred from the preceding (upstream) floating unit side over the insertion gap to the subsequent (downstream) floating unit side. In addition, the tip of the substrate may interfere with the subsequent floating unit. Therefore, there is a problem in that the substrate is damaged due to interference between the front end portion of the substrate and the subsequent floating unit, resulting in a decrease in the quality of the substrate.

  Note that even if the flying height (flying height) of the substrate by the flying unit is increased, the deflection of the tip of the substrate may not be offset within the realistic flying height range. Is not enough.

  Therefore, an object of the present invention is to provide a levitating and conveying apparatus having a novel configuration that can solve the above-described problems.

  The present invention is characterized in that, in a levitation transport apparatus that floats and transports a substrate in the transport direction, a transport mechanism (transport unit) that transports the substrate in the transport direction, and a transport mechanism (transport unit) that travels the substrate frame along the transport direction. The inside is connected to a floating gas supply source for supplying a floating gas, and a nozzle for ejecting the floating gas is formed on the upper surface. A floating gas reservoir layer (pressure reservoir layer) can be generated between the substrate and the substrate. A plurality of levitation units that levitate the substrate using the pressure of the levitation gas, and the substrate with respect to the plurality of levitation units between any of the levitation units adjacent to each other in the transport direction. An insertion gap for inserting a substrate receiving member for delivering or receiving is partitioned (formed), and a position adjacent to the upstream side of the insertion gap (on the upstream side of the insertion gap and in front of the insertion gap). An upward force is generated at the front end side of the substrate at a position close to the insertion gap) with the central portion of the floating gas reservoir layer generated between the floating unit and the substrate immediately upstream of the insertion gap as a fulcrum. Thus, the gist is that a downward force applying means (downward force applying mechanism) for locally applying a downward force to the substrate is provided.

  In the claims and specification of the present application, “provided” means not only directly provided but also indirectly provided via an interposed member such as a bracket. The “floating gas” is intended to include air, argon gas, nitrogen gas, and the like. The “upstream side” means the upstream side when viewed from the transport direction.

  According to the feature of the present invention, the floating gas is supplied to the inside of each floating unit by the floating gas supply source, the floating gas is ejected from the nozzle of each floating unit, and the transport mechanism is appropriately operated. As a result, the substrate can be floated and transported in the transport direction (conveyed in a floating state) while generating a floating gas pool layer between the substrate and the plurality of the floating units.

  Then, before the front end of the substrate is transferred from the preceding (upstream) floating unit to the subsequent (downstream) floating unit beyond the insertion gap, the substrate is locally directed downward by the downward applying means. Thus, an upward force is generated on the front end portion side of the substrate with the central portion of the floating gas pool layer generated between the floating unit and the substrate immediately upstream of the insertion gap as a fulcrum. This makes it possible to avoid interference between the front end of the substrate and the subsequent floating unit when transferring from the preceding floating unit side to the subsequent floating unit side beyond the insertion gap.

  In the specification of the present application, “preceding” means preceding when viewed from the transport direction, and “following” refers to following when viewed from the transport direction.

  According to the present invention, when transferring from the preceding levitation unit side to the subsequent levitation unit side, it is possible to avoid interference between the front end portion of the substrate and the subsequent levitation unit. It is possible to reliably prevent the substrate from being damaged when transferring to the subsequent floating unit beyond the insertion gap, and to maintain the quality of the substrate.

It is an expanded sectional view along the II line in FIG. It is a partial top view of the levitating conveyance apparatus which concerns on 1st Embodiment. It is a partial side view of the levitating conveyance apparatus which concerns on 1st Embodiment, Comprising: The conveyance mechanism is abbreviate | omitted. FIG. 4 is a view taken along line IV-IV in FIG. 2. It is an expanded sectional view along the VV line in FIG. It is an expanded sectional view along the VI-VI line in FIG. It is a partial top view of the levitation conveyance apparatus which concerns on 1st Embodiment which changed the arrangement | positioning aspect of an air suction device. FIG. 10 is an enlarged sectional view taken along line VIII-VIII in FIG. 9. It is a partial top view of the levitation conveyance device concerning a 1st embodiment which changed the arrangement mode of an air suction machine. It is an expanded sectional view along the XX line in FIG. It is a partial top view of the levitating conveyance apparatus which concerns on 2nd Embodiment. It is a partial expanded sectional view of the levitating conveyance apparatus which concerns on 3rd Embodiment, Comprising: It is a figure equivalent to FIG.

(First embodiment)
A first embodiment will be described with reference to FIGS. In the drawings, “FF” indicates the forward direction, “FR” indicates the backward direction, “L” indicates the left direction, and “R” indicates the right direction.

  As shown in FIGS. 2 to 4, the levitating and conveying apparatus 1 according to the first embodiment is an apparatus that levitates and conveys a substrate W such as a glass substrate in the conveying direction (rear direction), for example, along the front-rear direction. A plurality of device frames 3 arranged side by side are provided. Each device frame 3 includes a support base 5, a plurality of support columns 7 provided integrally below the support support 5, and a plurality of reinforcing members 9 provided so as to be connected to the plurality of support columns 7. And. Instead of including the plurality of device frames 3 arranged in the front-rear direction, the levitation transfer device 1 may include a device frame (not shown) extending in the front-rear direction.

  The plurality of apparatus frames 3 are provided with a transport mechanism (transport unit) 11 that transports the substrate W in the transport direction. The specific configuration of the transport mechanism 11 is as follows.

  That is, one or a plurality of (one or two in the first embodiment) support arms 13 are provided near the left end of each support base 5. A first transport roller 15 that supports one end surface (left end surface) of the substrate W is provided to be rotatable around a vertical axis. In other words, a plurality of first transport rollers 15 are provided in the vicinity of the left end portions of the plurality of support bases 5 at intervals along the front-rear direction via the plurality of support arms 13. Here, each of the first transport rollers 15 is a free roller that is rotatable around a vertical axis.

  Near the right end of each support base 5, a moving air cylinder 17 is provided. Each moving air cylinder 17 is connected to the cylinder main body 19 fixed to the support base 5 and the cylinder main body 19 in the transport direction. The piston rod 21 is provided so as to be movable in the conveyance width direction (left-right direction) orthogonal to each other. Further, a slider 23 is provided in the cylinder body 19 of each moving air cylinder 17 so as to be movable in the left-right direction, and the piston rod 21 in each moving air cylinder 17 is connected to an appropriate position of the corresponding slider 23. It is. Further, a second transport roller 25 that supports the other end surface (right end surface) of the substrate W is provided at the left end portion of each slider 23 so as to be rotatable around a vertical axis. In other words, a plurality of second transport rollers 25 are provided in the vicinity of the right ends of the plurality of support bases 5 at intervals along the front-rear direction via the plurality of moving air cylinders 17 and the plurality of sliders 23. Accordingly, each second transport roller 25 moves in the left-right direction integrally with the slider 23 by the operation of the moving air cylinder 17. The right end of each slider 23 is provided with a rotation motor 27 that rotates the corresponding second transport roller 25, and the motor shaft (not shown) of each rotation motor 27 corresponds to the corresponding second. The roller shaft of the conveying roller 25 is interlocked and connected.

  Instead of using the first transport roller 15 as a free roller and the second transport roller 25 as a driving roller that is rotated by driving a motor such as the rotation motor 27, the first transport roller 15 is used as a drive roller, and the second transport roller is rotated. The roller 25 may be a free roller, or the first transport roller 15 and the second transport roller 25 may be drive rollers. Further, instead of the transport mechanism 11 having a plurality of first transport rollers 15 and a plurality of second transport rollers 25, etc., transport that supports the back surface of the substrate W and is rotatable around an axis parallel to the transport width direction. Another transport mechanism (not shown) including a roller or the like may be used.

  As shown in FIGS. 2 to 5, each support base 5 is provided with one or a plurality of chambers 29 (one or two in the first embodiment) for storing air as a floating gas. Each chamber 29 extends in the left-right direction. A plurality of lower through holes 31 are provided on the lower surface of each chamber 29, and a plurality of upper through holes 33 are spaced on the upper surface of each chamber 29 along the left-right direction and / or the front-rear direction. Is provided. Further, a supply fan (a fan filter unit in the first embodiment) 35 as an air supply source for supplying air to the inside of the chamber 29 is provided at the peripheral portion of each lower through hole 31 in each chamber 29. It has been.

  At the peripheral edge of each upper through-hole 33 in each chamber 29, a hollow floating unit 37 that floats the substrate W using the pressure of air is provided. A plurality of floating units 37 are provided at intervals along the transport direction and the transport width direction via the plurality of chambers 29 and the like. Further, the side view shape (see FIG. 3) and the front view shape (see FIG. 4) of each levitation unit 37 are each T-shaped, and the interior of each levitation unit 37 is supplied via a chamber 29. It is connected to the fan 35. Further, a frame-like nozzle 39 for ejecting air is provided on the upper surface of each floating unit 37 along the planar view shape of the floating unit 37, and each floating unit 37 has a floating gas between itself and the substrate W. It is possible to generate an air reservoir layer (pressure reservoir layer) S (see FIG. 4) as a reservoir layer. Here, as shown in JP-A-2006-182563, each nozzle 39 is inclined toward the center side of the levitation unit 37 with respect to the vertical direction (direction perpendicular to the upper surface of the levitation unit 37). . In addition, instead of the frame-shaped nozzles 39 being provided on the upper surface of each floating unit 37 along the planar view shape of the floating unit 37, a plurality of nozzles (not shown) in the shape of slits or small holes (not shown) are provided. You may make it provide along a planar view shape.

  As shown in FIGS. 2 and 3, a substrate receiving member 41 that transfers or receives a substrate W to / from a plurality of floating units 37 is inserted between any floating units 37 that are adjacent to each other in the transport direction. A plurality of insertion gaps IG (only one is shown in FIGS. 1, 2, and 3) are formed, and each insertion gap IG extends in the left-right direction, and is normally connected between the floating units 37. It is wider than the installation gap PG. Here, examples of the substrate receiving member 41 include a known substrate receiving fork as shown in Japanese Patent Laid-Open No. 7-311375 and a substrate support member (substrate in a substrate cassette as shown in Japanese Patent Laid-Open No. 2005-159141. A part of the cassette).

  At a position close to the upstream side of each insertion gap IG (a position upstream of each insertion gap IG and close to each insertion gap IG), an air suction unit 43 that sucks air from below is provided for each insertion gap IG. Each air suction device 43 extends in the left-right direction. And the concrete structure of each air suction device 43 is as follows.

  That is, as shown in FIGS. 1 and 2, a suction case 45 is provided at a position close to the upstream side of the insertion gap IG in an appropriate support base 5, and the suction case 45 extends in the left-right direction. Yes. The suction case 45 has a slit-like suction port 47 opened on the upper side, and a plurality of (only one is shown in FIG. 1) through holes 49 are formed on the lower surface of the suction case 45. Is formed. Here, the suction port 47 of the suction case 45 is separated from the insertion gap IG by the length of the floating unit 37 for one row (length in the front-rear direction).

  A plurality of support rollers 51 that support the back surface of the substrate W are provided in the suction case 45 so as to be rotatable about an axis parallel to the transport width direction, and each support roller 51 is parallel to the transport width direction. It is a free roller that can rotate around its axis, and projects upward with respect to the uppermost portion of the suction case 45. Note that each support roller 51 may be a drive roller instead of a free roller, or a plurality of support rollers 51 may be omitted from the air suction unit 43.

  A suction fan 53 as an air suction source for sucking air from the inside of the suction case 45 is provided at the peripheral edge of each through hole 49 of the suction case 45. As shown in FIG. 1, the air suction unit 43 is configured so that the tip of the substrate W is supported by using the central portion of the air pool layer S generated between the floating unit 37 and the substrate W immediately upstream of the insertion gap IG as a fulcrum. A downward force is locally applied to the substrate W by the suction force of the suction fan 53 so as to generate an upward force on the part side. In other words, the air suction device 43 can be regarded as one of downward force applying means (downward force applying mechanism) that locally applies a downward force to the substrate W. A reflective photoelectric sensor (not shown) that detects that the tip of the substrate W is close to the insertion gap IG while monitoring the reflected light from the substrate W is used, based on the output signal of the reflective photoelectric sensor. You may make it start the drive of the suction fan 53. FIG.

  As shown in FIGS. 6 and 7, the center of the air reservoir layer S generated between the floating unit 37 and the substrate W immediately upstream of the insertion gap IG is used as a fulcrum, and is directed upward toward the tip of the substrate W. If a downward force is locally applied to the substrate W by the suction force of the suction fan 53 so as to generate a force, the suction ports 47 of the suction case 45 are provided for a plurality of rows from the insertion gap IG ( 6 and 7 may be separated by the length of the floating unit 37 (for two rows). Further, as shown in FIGS. 8 and 9, the subsequent (downstream side) is caused by the suction force of the suction fan 53 in the air suction unit 43 provided at the upstream position of the preceding (upstream side) insertion gap IG. The substrate W is configured to generate an upward force on the tip side of the substrate W with the central portion of the air reservoir layer S generated between the floating unit 37 and the substrate W immediately upstream of the insertion gap IG as a fulcrum. As long as a downward force is applied locally, the air suction unit 43 may not be provided for each insertion gap IG.

  Then, the effect | action and effect of embodiment of this invention are demonstrated.

  Each supply fan 35 supplies air to the inside of each floating unit 37 through the chamber 29, whereby air is ejected from the nozzle 39 of each floating unit 37. In addition, each second conveyance roller 25 is moved leftward by the operation of each moving air cylinder 17, and each second conveyance roller 25 is rotated by driving each rotation motor 27. Thus, the pressure accumulation layer S is generated between the substrate W and the plurality of floating units 37, and the substrate W is supported from both sides by the cooperation of the plurality of first transport rollers 15 and the plurality of second transport rollers 25. On the other hand, it can be levitated and conveyed in the conveying direction (conveyed in the state of being levitated).

  Then, before the leading end of the substrate W is transferred from the preceding (upstream) floating unit 37 side over the insertion gap IG to the subsequent (downstream) floating unit 37 side, suction of the suction fan 53 in the air suction unit 43 is performed. A downward force is locally applied to the substrate W by the force, and the central portion of the air pool layer S generated between the floating unit 37 and the substrate W immediately upstream of the insertion gap IG is used as a fulcrum. An upward force is generated on the tip end side. This makes it possible to avoid interference between the leading end portion of the substrate W and the subsequent floating unit 37 when transferring from the preceding floating unit 37 side to the subsequent floating unit 37 side beyond the insertion gap IG.

  Therefore, according to the first embodiment, the substrate W is reliably prevented from being damaged when transferring from the preceding floating unit 37 side to the subsequent floating unit 37 side beyond the insertion gap IG, and the quality of the substrate W is maintained. can do.

(Second Embodiment)
A second embodiment will be described with reference to FIGS. 10 and 11. In the drawings, “FF” indicates the forward direction, “FR” indicates the backward direction, “L” indicates the left direction, and “R” indicates the right direction.

  As shown in FIGS. 10 and 11, the levitation transport device 55 according to the second embodiment levitates and transports the substrate W in the transport direction (backward direction), and the levitation transport device 1 according to the first embodiment. And substantially the same configuration. Then, the levitation transport device 55 according to the second embodiment replaces the air suction unit 43 in the levitation transport device 1 according to the first embodiment, and is located close to the upstream side of each insertion gap IG (of each insertion gap IG). A plurality of air suction devices 57 that are provided on the upstream side and in the vicinity of each insertion gap IG) are spaced apart in the left-right direction and suck air from below. The typical configuration is as follows. In addition, about the component corresponded in the levitation conveyance apparatus 1 which concerns on 1st Embodiment among several components in the levitation conveyance apparatus 55 which concerns on 2nd Embodiment, the same number is attached | subjected in a figure. Yes.

  That is, a suction case 59 is provided at a position close to the upstream side of the insertion gap IG on an appropriate support base 5, and the suction case 59 extends in the front-rear direction. The suction case 59 has an open suction port 61 on the upper side, and a through hole 63 is formed in the lower surface of the suction case 59. Further, a plurality of support rollers 65 that support the back surface of the substrate W are provided in the suction case 59 so as to be rotatable about an axis parallel to the transport width direction. Each support roller 51 is provided in the transport width direction. It is a free roller that can freely rotate around a parallel axis, and protrudes upward with respect to the uppermost portion of the suction case 59. Note that each support roller 51 may be a driving roller instead of a free roller, or the plurality of support rollers 51 may be omitted from the air suction unit 57.

  A suction fan 67 as an air suction source for sucking air from the inside of the suction case 59 is provided at the peripheral portion of the through hole 63 of the suction case 59. As shown in FIG. 10, the plurality of air suction devices 57 separated in the left-right direction are provided in the central portion of the air pool layer S generated between the floating unit 37 and the substrate W immediately upstream of the insertion gap IG. As a fulcrum, a downward force is locally applied to the substrate W by the suction force of the suction fan 67 so that an upward force is generated on the tip end side of the substrate W.

  In the second embodiment, the same operations and effects as the operations and effects of the first embodiment are achieved.

(Third embodiment)
A third embodiment will be described with reference to FIG. In the drawings, “FF” indicates the forward direction, “FR” indicates the backward direction, “L” indicates the left direction, and “R” indicates the right direction.

  As shown in FIG. 12, the levitation transport device 69 according to the third embodiment levitates and transports the substrate W in the transport direction (backward direction), and is substantially the same as the levitation transport device 1 according to the first embodiment. It has a configuration. And the levitating conveyance apparatus 69 which concerns on 3rd Embodiment replaces with the air suction device 43 in the levitation conveyance apparatus 1 which concerns on 1st Embodiment, and the position (upstream of each insertion gap IG) of the upstream side of each insertion gap IG. The air sprayer 71 is provided on the upstream side and in the vicinity of each insertion gap IG) and blows air from above, and the specific structure of the air sprayer 71 is as follows. Become. In addition, about the component corresponded in the levitation conveyance apparatus 1 which concerns on 1st Embodiment among several components in the levitation conveyance apparatus 69 which concerns on 3rd Embodiment, the same number is attached | subjected in a figure. Yes.

  That is, a plurality of spray nozzles 73 (only one is shown in FIG. 12) capable of spraying air from above are provided through the support arm 75 at positions close to the upstream side of the insertion gap IG on an appropriate support base 5. Are provided at intervals in the left-right direction. Each spray nozzle 73 is connected to an air pump 77 as an air supply source for supplying air via an air pipe 79. The air sprayer 71 applies an upward force to the tip side of the substrate W with the central portion of the air reservoir layer S generated between the floating unit 37 and the substrate W immediately upstream of the insertion gap IG as a fulcrum. A downward force is locally applied to the substrate W by the spray force of the plurality of spray nozzles 73 so as to be generated. In other words, the air sprayer 71 can be regarded as one of downward force applying means (downward force applying mechanism) that locally applies a downward force to the substrate W.

  Next, main functions and effects of the third embodiment will be described.

  Before the tip of the substrate W is transferred from the preceding floating unit 37 side to the subsequent floating unit 37 side beyond the insertion gap IG, it is locally applied to the substrate W by the spraying force of the plurality of spray nozzles 73 in the air sprayer 71. Thus, a downward force is applied, and an upward force is applied to the front end portion side of the substrate W with the central portion of the air pool layer S generated between the floating unit 37 and the substrate W immediately upstream of the insertion gap IG as a fulcrum. Is generated. This makes it possible to avoid interference between the leading end portion of the substrate W and the subsequent floating unit 37 when transferring from the preceding floating unit 37 side to the subsequent floating unit 37 side beyond the insertion gap IG.

  Therefore, according to the third embodiment, the same effects as those of the first embodiment can be obtained.

  In addition, this invention is not restricted to description of the above-mentioned embodiment, It can implement in a various aspect. Further, the scope of rights encompassed by the present invention is not limited to these embodiments.

IG insertion gap S Air accumulation layer (pressure accumulation layer)
W substrate 1 levitation transport device 3 device frame 11 transport mechanism 15 first transport roller 17 moving air cylinder 23 slider 25 second transport roller 27 rotating motor 29 chamber 35 supply fan 37 levitation unit 39 nozzle 41 substrate receiving member 43 air suction 45 Suction case 47 Suction port 51 Support roller 53 Suction fan 55 Levitation transport device 57 Air suction device 59 Suction case 61 Suction port 65 Support roller 67 Suction fan 69 Levitation transport device 71 Air sprayer 73 Spray nozzle 77 Air pump

Claims (7)

In a levitation transport device that levitates and transports a substrate in the transport direction,
A transport mechanism provided in the apparatus frame for transporting the substrate in the transport direction;
The apparatus frame is provided along the transport direction, the inside is connected to a floating gas supply source that supplies floating gas, a nozzle that blows floating gas is formed on the upper surface, and a floating gas reservoir layer is formed between the substrate and the substrate. A plurality of levitation units that can be generated and levitate the substrate using the pressure of the levitation gas;
Between any of the floating units that are adjacent to each other in the transport direction, an insertion gap for inserting a substrate receiving member that transfers or receives a substrate to and from the plurality of the floating units is partitioned and formed.
At a position close to the upstream side of the insertion gap, the center of the floating gas reservoir layer generated between the floating unit and the substrate immediately upstream of the insertion gap is used as a fulcrum and is directed upward toward the tip of the substrate. A levitating and conveying apparatus characterized in that a downward force applying means for locally applying a downward force to a substrate is provided so as to generate a force.   2. The levitation conveyance apparatus according to claim 1, wherein a plurality of the levitation units are provided on the apparatus frame along the conveyance direction and a conveyance width direction orthogonal to the conveyance direction.   The levitation conveyance apparatus according to claim 1, wherein the nozzle of each levitation unit is configured to be inclined toward the center of each levitation unit with respect to a vertical direction.   The levitation conveyance apparatus according to any one of claims 1 to 3, wherein the downward force applying means is an air suction device that sucks air from below. The air aspirator is
A suction case provided on the apparatus frame and having a suction port opened on the upper side;
The levitation conveyance apparatus according to claim 4, further comprising: an air suction source that is connected to the inside of the suction case and sucks air. The air aspirator is
In addition to the suction case and the air suction source, the suction case is further provided in the suction case so as to be rotatable around an axis parallel to the transport width direction orthogonal to the transport direction, and with respect to the uppermost portion of the suction case. The levitation conveyance apparatus according to claim 5, further comprising a support roller that protrudes upward and supports the back surface of the substrate.   The levitation conveyance apparatus according to any one of claims 1 to 3, wherein the downward force applying means is an air sprayer that blows air from above.

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