The present invention relates to a transport system and a control method of the transport system.
A non-contact type transport system controls the position and attitude of a mover while maintaining a floating state, and transports the mover by driving the mover in the transport direction. When an abnormality occurs in the control state of the mover due to an abnormality or the like of a sensor for detecting the position of the mover, the mover may be brought into contact with the transport path and stopped. When the transport is resumed after the cause of the abnormality is removed, a process of transition from the contact state to the floating state is performed. When transition from the contact state to the floating state, control is performed to float the mover by a method different from the transport state.
Japanese Patent Application Laid-Open No. H09-19004 discloses a suction-type magnetic levitation vehicle. In the Japanese Patent Application Laid-Open No. H09-19004, the instantaneous power at the start of floating or landing is reduced by transitioning the time of the start of floating or landing such that a plurality of dollies do not float or land simultaneously.
Japanese Patent Application Laid-Open No. H09-19004 discloses reducing instantaneous power of the entire transport system for controlling a plurality of dollies. However. In Japanese Patent Application Laid-Open No. H09-19004, regarding the return from landing condition to floating condition, a study focusing on individual dolly has not been made.
According to an aspect of the present invention, there is provided a transport system including: a stator having a first magnetic force unit; a mover having a second magnetic force unit; and a control unit. The control unit controls a magnetic force acting between the first magnetic force unit and the second magnetic force unit to transport the mover in a first direction. The stator has a first regulating member row including a plurality of first regulating members and a second regulating member row including a plurality of second regulating members, the mover, in a second direction intersecting the first direction, being disposed between the first regulating member row and the second regulating member row. The control unit performs a first process of applying a rotational force to the mover such that one of the first regulating members in the first regulating member row serves as a fulcrum when the mover contacts the first regulating member row.
According to another aspect of the present invention, there is provided a transport system including: a stator having a first magnetic force unit; a mover having a second magnetic force unit; and a control unit. The control unit controls a magnetic force acting between the first magnetic force unit and the second magnetic force unit to transport the mover in a first direction. The mover has two side surfaces in a second direction intersecting the first direction and has a plurality of first regulating members disposed on one side surface and a plurality of second regulating members disposed on the other side surface of the mover. The control unit performs a first process of applying a rotational force to the mover such that one of the first regulating members of the first regulating member row serves as a fulcrum when the first regulating member row of the mover contacts the stator.
According to another aspect of the present invention, there is provided a control method of a transport system including a stator having a first magnetic force unit; a mover having a second magnetic force unit; and a control unit. The control unit controls a magnetic force acting between the first magnetic force unit and the second magnetic force unit to transport the mover in a first direction. The stator has a first regulating member row including a plurality of first regulating members and a second regulating member row including a plurality of second regulating members, the mover, in a second direction intersecting the first direction, being disposed between the first regulating member row and the second regulating member row. The control method comprises: preforming a first process of applying a rotational force to the mover such that one of the first regulating members of the first regulating member row serves as a fulcrum when the mover contacts the first regulating member row.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding elements are denoted by the same reference numerals, and the description thereof may be omitted or simplified. In addition, the same kind of constituent elements arranged at different positions may be distinguished by adding a lower case letter alphabet to the end of the same numeral as an identifier. In addition, when there is no need to be particularly distinguished and described, a sign of only a numeral may be used without attaching an identifier.
First, an overall configuration of a transport system according to the present embodiment will be described with reference to
As illustrated in
The transport system according to the present embodiment may be a system that transports a workpiece 102 on the mover 101 to a processing apparatus or the like that performs a processing operation on the workpiece 102. The mover 101 may have a holding mechanism for holding the workpiece 102 such as a workpiece holder on the mover 101 by transporting the mover 101.
Here, coordinate axes, directions, and the like used in the following description will be defined with reference to
Next, the mover 101 to be transported in the transport system according to the present embodiment will be described with reference to
As illustrated in
Each of permanent magnets constituting the permanent magnet group 103 is attached to a yoke 107 provided on the upper surface of the mover 101. The yoke 107 is made of a material having a high magnetic permeability such as iron. In the example of
The mover 101 transported on the stator 201 has a linear scale 104, a Y target 105, and a plurality of Z targets 106. Each of the linear scale 104, the Y target 105, and the Z target 106 is attached to, for example, the bottom of the mover 101 along the X direction. The Z targets 106 are attached to both sides of the linear scale 104 and the Y target 105, respectively.
The stator 201 includes a plurality of coils 202 (first magnetic force units), a plurality of linear encoders 203, a plurality of Y sensors 204, and a plurality of Z sensors 205. As illustrated in
The current of the plurality of coils 202 is controlled, for example, in units of three coils. When the coil 202 is energized, the coil 202 generates a magnetic force with the permanent magnet group 103 of the mover 101 to apply a force to the mover 101.
Each of the coils 202 is arranged such that the center of the two permanent magnets 103c in the Y direction coincide with the center of the coil 202 in the Y direction. The same applies to the permanent magnets 103d, 103e, and 103f. When the coils 202 opposed to the permanent magnet 103c, 103d, 103e, and 103f is energized, each of the permanent magnet 103c, 103d. 103e, and 103f receives a force in the Y direction.
The coils 202 face the permanent magnets 103a and 103b. When the coils 202 are energized, the permanent magnets 103a and 103b receive forces in the X direction and the Z direction.
The plurality of linear encoders 203 are attached to the stator 201 along the X direction so as to be able to face the linear scale 104 of the mover 101. Each of linear encoders 203 can detect and output a relative position of the mover 101 with respect to the linear encoder 203 by reading the linear scale 104 attached to the mover 101.
The plurality of Y sensors 204 are attached to the stator 201 along the X direction so as to be able to face the Y target 105 of the mover 101, respectively. Each of Y sensors 204 can detect and output a relative distance in the Y direction between the Y sensor 204 and the Y target 105 attached to the mover 101.
The plurality of Z sensors 205 are attached to the stator 201 in two rows along the X direction so as to be able to face the Z target 106 of the mover 101. Each of Z sensors 205 can detect and output a relative distance in the Z direction between the Z sensor 205 and the Z target 106 attached to the mover 101.
The Y roller 206 is a regulating member for regulating the stroke of the mover 101 in the Y direction, and is disposed on the stator 201. A plurality of Y rollers 206 are arranged along the X direction, which is the transporting direction, to form a Y roller group. In order to regulate the positive side stroke and the negative side stroke in the Y direction, the Y roller group is arranged on the positive side and the negative side in the Y direction such that Y roller groups 206p and 206q (first regulating member row and second regulating member row) in two rows are formed. Similarly, in order to regulate the positive stroke and the negative stroke in the Z direction, Z roller groups (not illustrated) may be arranged in two rows. Each of the above-mentioned rollers has a role of limiting the stroke in the Y direction and the Z direction, and has a role of enabling transport in a contact state when the mover 101 contacts these rollers. Instead of the Y roller 206, a regulating member such as a stopper having no rotation mechanism may be used.
The transport system has an integrated controller (not illustrated). The integrated controller is a control unit of the transport system. The integrated controller detects the positional relationship between the stator 201 and the mover 101, grasps the positional relationship between the coil 202 and the permanent magnet group 103, and causes an appropriate current to flow through the coil 202, thereby realizing six-axis control at the center O.
Next, the two states in this embodiment, a state in which the mover 101 can be transported without contacting the stator 201, and a state in which the mover 101 is stopped by contacting the stator 201, are explained by using
The wider the Y control range, the more suitable the mover 101 can be controlled. However, there is a limit to the width of the Y control range in design for the following reason. In order to widen the Y control range, it is necessary to increase the size of the coil 202 so as to increase the thrust that can be generated in the Y direction. This causes a factor that increases the size and cost of the apparatus. Further, the thrust in the Y direction required during normal workpiece transport is smaller than the thrust required to transition from a state in which the mover 101 is in contact with the Y roller to a state in which transport of the mover 101 can be performed in a non-contact manner. Therefore, even if the size of the coil 202 is increased along with an increase in size of the apparatus and an increase in cost, it does not contribute to an improvement in transport performance during normal transport of the transport system. Considering such a design aspect, it may not be possible to design the Y control range to be sufficiently wide.
On the other hand, the Y stroke is designed to be large to some extent from the following aspect. When the dimension error of the mover 101 or the transport accuracy of the mover 101 is larger than that of the Y stroke, the Y roller 206 and the mover 101 may come into contact with each other during transport. In this case, the non-contact transport cannot be realized, and the transport accuracy may be further degraded. To reduce the possibility of such contact, the Y stroke is designed to be somewhat wide.
For the above reasons, the transport system according to the present embodiment applies a configuration in which the Y stroke is sufficiently large with respect to the Y control range. Therefore, when the mover 101 is separated from the center of the transport path to some extent, the center O of the mover 101 may be out of the Y control range. The transport system of the present embodiment has a function of return process when the mover 101 stops in contact with the Y roller group in a state in which the center O of the mover 101 is out of the Y control range. Hereinafter, the return process will be described.
As described above, during normal transport, the position of the mover 101 is controlled such that the mover 101 is not in contact with the stator 201 and the center O is within the Y control range. However, in a situation in which the transport of the mover 101 is controlled to be stopped, or in a situation in which the six-axis control is stopped due to abnormality of the control system or the like, the mover 101 is in contact with the Y roller group in any one of the modes illustrated in
The mover 101 stops in any one of the modes illustrated in
The reason why these stopped states occur is that, in the transport system according to the present embodiment, the mover 101 which is stopped receives the magnetic attraction force in the Y direction due to the magnetic force between the plurality of coils 202 and the permanent magnet group 103. The arrows in
An example of an operation sequence from the state illustrated in
In the following description of
In step S1, the integrated controller of the transport system activates (turns on) the position control for the four axes Z, Wy, Wx, and X of the six axes. In step S2, the integrated controller determines a contact pattern. When the state of the mover 101 is the contact pattern (a) (YES in step S2), the process proceeds to step S3a. When the state of the mover 101 is the contact pattern (b) or the contact pattern (c) (NO in step S2), the process proceeds to step S6a.
In step S3a, the integrated controller controls the linear encoder 203 to acquire a position (X-coordinate) of the mover 101 in the X direction and determines whether or not the mover 101 is located at a position in the X direction where the mover 101 can transition to the non-contact state. A specific example of a method of determining whether or not transition to the non-contact state is possible will be described later.
If it is determined in step S3a that the mover 101 is located at a position in the X direction where the mover 101 can transition to the non-contact state (YES in step S3a), the process proceeds to step S4. When it is determined that the mover 101 is located at a position in the X direction where the mover 101 cannot transition to the non-contact state (NO in step S3a), the process proceeds to step S3b.
In step S3b, the integrated controller controls the mover 101 so as to move to a position in the X direction in which the mover 101 can transition to the non-contact state while maintaining the mover 101 in contact with the Y roller group.
In step S4, the integrated controller switches the reference of the position control in the X direction from the center O of the mover 101 to the contact point between the mover 101 and the Y roller 206a located closest to the positive side in the X direction among the Y rollers in contact with the mover 101. Thus, the integrated controller can control the mover 101 to rotate about the contact point as a fulcrum between the Y roller 206a and the mover 101. The switching of the control will be described with reference to
Xfb=Xscale−r1 sin Wz (1)
Here, Xfb is a feedback value of X direction control, that is, a position of the center O, and r1 is a distance from the linear encoder 203 to the center O.
Xfb=Xscale−r2 sin Wz (2)
In step S5, the integrated controller performs a process (first process) of rotating the mover 101 in the positive direction of the Wz-axis and abutting the mover 101 against one Y roller 206b of the Y roller group opposed to the Y direction. Hereinafter, this operation is sometimes referred to as Wz rotation centering.
Here, the direction of thrust generated in the permanent magnet group 103 during the Wz rotation centering in step S5 will be described with reference to
Although
As illustrated in
In step S6a, the integrated controller determines whether or not the center O of the mover 101 is within the Y control range. When it is determined that the center O of the mover 101 is within the Y control range (YES in step S6a), the process proceeds to step S7. When it is determined that the center O of the mover 101 is outside the Y control range (NO in step S6a), the process proceeds to step S6b.
In step S6b, the integrated controller moves the mover 101 by a minute amount Δx in the X direction such that the center O of the mover 101 enters the Y control range. As described above, the position of the mover 101 in the X direction is controlled in steps S3a and S3b such that the center O enters the Y control range after the Wz rotation centering. However, the center O may not enter the Y control range after Wz rotation centering due to factors such as slippage between the Y roller 206a and the mover 101. In the process of step S6b, by moving the mover 101 in the X direction in such a case, the position of the mover 101 can be adjusted such that the center O of the mover 101 enters the Y control range.
In step S7, the integrated controller switches to control in the X direction and the Y direction about the center O of the mover 101 as the rotation center. In step S8, the integrated controller enables control of the Wz-axis. Then, while maintaining the position of the center O, the integrated controller performs a process (fourth process) of returning the attitude of the mover 101 by rotating the mover 101 around the Wz-axis by applying a rotational force opposite to that in the Wz rotation centering.
In step S9, the integrated controller enables control in the Y direction. Then, the mover 101 is moved in the Y direction by a minute amount Δy such that the center O of the mover 101 is aligned with the center axis of the Y control range. As described above, as in any one of
Next, in step S3a of
First, the first determination condition will be described with reference to
In
Comparing
Next, the second determination condition will be described with reference to
In
When Wz rotation centering is performed in a positional relationship in which the lengths of L1 and L2 are different as illustrated in
However, even when there is a difference between the lengths of L1 and L2, if the difference between the center O and the Y control range after the Wz rotation centering is minute, the center O can reach the Y control range by the process of step S6b. Therefore, although it is desirable to include it in the determination criteria in step S3a of
The rotation direction in the Wz rotation centering illustrated in
As described above, in the present embodiment, the plurality of Y rollers 206 are arranged on the stator 201. The integrated controller of the transport system controls the mover 101 to rotate about one Y roller 206a as a fulcrum when the mover 101 stops in contact with the plurality of Y rollers 206. Thus, the center O of the mover 101 can be moved within the Y control range against the magnetic attraction force to transition to the non-contact state. Therefore, according to the present embodiment, there is provided a transport system that can suitably realize transition from a state in which the mover 101 is in contact with the stator 201 to a state in which the mover 101 is not in contact with the stator 201.
This embodiment is an example of the positional relationship between the mover 101 and the Y roller 206 that can reduce the torque required for the Wz rotation centering in step S5 of
As illustrated in
Next, with reference to
On the other hand, the condition of Y 1 for moving the center O of the mover 101 to the center of the transport path is expressed by the following formula (5) using Br and B illustrated in
Substituting Formula (4) into Formula (5) leads to Formula (6) below.
Solving Formula (6) for L5 leads to Formula (7) below.
In
Next, the position of the Y roller 206b disposed at a position opposed to the Y roller 206a serving as a fulcrum will be described with reference to
When the mover 101 rotates in the direction illustrated in
Assuming that the distance between the Y roller 206a and the Y roller 206b in the X direction is L6, the Y roller 206d is positioned away from the Y roller 206a by L6+P in the negative direction of the X-axis. The end portion of the mover 101 is located away from the Y roller 206a by L5+L/2 in the negative direction of the X-axis. Therefore, a condition for preventing the mover 101 from abutting on the Y roller 206d when the mover 101 rotates is expressed by the following formula (9).
Next, the optimal value of L6 will be described with reference to
However, L6 does not necessarily have to completely match the value indicated in formula (10), and can be appropriately set such that the center O of the mover 101 can reach the Y control range.
Next, the relationship between the Wz torque and L5 will be described with reference to
As illustrated by arrows in
Therefore, the smaller L5 is, the smaller the Wz torque for rotating the mover 101 can be. Accordingly, by setting L5 to a minimum within a range satisfying any of the above conditional formulas, the Wz torque required for transitioning the mover 101 from the contact state to a state in which the mover 101 can be transported in a non-contact state can be minimized.
As described above, in the present embodiment, there is provided the transport system that can more suitably realize the transition from the state in which the mover 101 is in contact with the stator 201 to the state in which the mover 101 is not in contact with the stator 201. Note that none of the conditions described in the present embodiment is essential. The transport system may be configured to satisfy some of the conditions described in the present embodiment.
Although the Y roller 206 is disposed on the stator 201 in the above-described embodiment, the present invention is not limited to this, and the Y roller 206 may be disposed on the mover 101. In the present embodiment, an example in which the Y roller 206 is disposed on the mover 101 will be described. Description of elements common to the first embodiment or the second embodiment may be omitted or simplified.
The stator 201 has a side wall on which the Y roller 206e, 206f, 206g, and 206h disposed on the mover 101 can come into contact when the mover 101 is stopped. As illustrated in
Let L7 be the distance in the X direction from the center O of the mover 101 to the Y rollers 206e, 206f, 206g, and 206h. As described with reference to
However, in the present embodiment, since the Y rollers 206e, 206f, 206g, and 206h are disposed on the mover 101, L7 does not depend on the position of the mover 101 in the X direction. Therefore, in the present embodiment, the restriction condition related to the position in the X direction or the process of changing the position in the X direction as described in the first embodiment or the second embodiment is not necessary. That is, in the present embodiment, the process of transition from the state in which the mover 101 is in contact with the stator 201 to the state in which the mover 101 is not in contact with the stator 201 can be performed without depending on the position in the X direction. Therefore, in the present embodiment, control is simplified compared to the first embodiment and the second embodiment.
As described above, according to the present embodiment, there is provided a transport system that can suitably realize transition from a state in which the mover 101 is in contact with the stator 201 to a state in which the mover 101 is not in contact with the stator 201.
The processing system 1 includes a transport system 10 according to the first to third embodiments and a processing apparatus 20. The transport system 10 includes a transport apparatus 11 including the mover 101, the stator 201, the Y roller 206, and the like described in the first to third embodiments, and a controller 12 which is the integrated controller described in the first to third embodiments. The transport apparatus 11 is controlled by the controller 12.
The processing apparatus 20 is an apparatus for manufacturing an article by processing on a workpiece. The application of the processing apparatus 20 is not particularly limited, but may be, for example, an assembly apparatus for industrial products, an evaporation apparatus for forming a thin film on a substrate as a workpiece, a film forming apparatus such as a sputtering apparatus, or an exposure apparatus for photolithography. A film forming apparatus such as an evaporation apparatus or a sputtering apparatus is provided in a vacuum apparatus. The film to be formed is, for example, a thin film, and its raw material is an organic material or a metal material (metal or metal oxide). The transport system 10 transports a workpiece such as a component, a semi-finished product, or a semiconductor substrate to the processing apparatus 20. The workpiece is transported into the processing apparatus 20 by the mover 101. The processing apparatus 20 processes a workpiece. An article manufactured by performing film formation on a substrate such as a glass substrate as a workpiece is, for example, an organic electronic device such as an organic EL display device or a thin-film solar cell. The organic EL display device is used, for example, in a display panel of a mobile device such as a smartphone.
In general, if a guide device having a sliding portion is used in the processing apparatus 20 as described above, contaminants generated from the sliding portion may deteriorate productivity. Examples of such contaminants include rail and bearing wear pieces, lubricating oil, and volatiles of lubricating oil. The transport system 10 according to the first to third embodiments can reduce the generation of contaminants by transporting a workpiece in a non-contact manner. Therefore, the processing system 1 of the present embodiment is more effective in applications requiring cleanliness such as an industrial product assembly process and a semiconductor device manufacturing process.
According to the present embodiment, the processing system 1 to which the transport system 10 according to the first to third embodiments is applied is provided.
It should be noted that all of the above-described embodiments are merely examples of implementation for carrying out the present invention, and the technical scope of the present invention should not be construed as being limited thereto. For example, although the above embodiment has been described by way of example with the mover 101 is in contact with the stator 201 and stopped, the mover 101 need not be completely stopped, and the present invention can also be applied even when the mover 101 in contact with the stator 201 without stopping. The hardware configuration, software configuration, processing flow, dimensions, shape, and the like in the above description do not limit the scope of the present invention. That is, the present invention can be implemented in various forms without departing from the technical idea thereof or the main characteristics thereof. For example, it is to be understood that an embodiment in which a part of the configuration of any of the embodiments is added to another embodiment or an embodiment in which a part of the configuration of any of the other embodiments is substituted is also an embodiment to which the present invention can be applied.
Embodiment(s) of the present invention can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as a ‘non-transitory computer-readable storage medium’) to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2020-182799, filed Oct. 30, 2020, which is hereby incorporated by reference herein in its entirety.
Number | Date | Country | Kind |
---|---|---|---|
2020-182799 | Oct 2020 | JP | national |
Number | Name | Date | Kind |
---|---|---|---|
4727813 | Matsuo | Mar 1988 | A |
5906262 | Miki | May 1999 | A |
10118774 | Tomoda et al. | Nov 2018 | B2 |
10294042 | Tomoda et al. | May 2019 | B2 |
10370279 | Ezawa | Aug 2019 | B2 |
10562720 | Yamamoto | Feb 2020 | B2 |
10581308 | Yamamoto | Mar 2020 | B2 |
10625948 | Fujii et al. | Apr 2020 | B2 |
10669106 | Yamamoto | Jun 2020 | B2 |
10745203 | Tomoda et al. | Aug 2020 | B2 |
10889449 | Umeyama et al. | Jan 2021 | B2 |
10944314 | Yamamoto | Mar 2021 | B2 |
10965201 | Ota et al. | Mar 2021 | B2 |
11179803 | Mizuno et al. | Nov 2021 | B2 |
20070103660 | Tanaka | May 2007 | A1 |
20150008768 | Achterberg | Jan 2015 | A1 |
20150142182 | Kimura et al. | May 2015 | A1 |
20160325761 | Pruessmeier | Nov 2016 | A1 |
20160347550 | Paweletz | Dec 2016 | A1 |
20170324304 | Ito | Nov 2017 | A1 |
20190100389 | Neubauer | Apr 2019 | A1 |
20190367297 | Hartung | Dec 2019 | A1 |
20200052568 | Yamamoto | Feb 2020 | A1 |
20210094764 | Umeyama et al. | Apr 2021 | A1 |
20210159769 | Yamamoto | May 2021 | A1 |
20210184555 | Ota | Jun 2021 | A1 |
20210242765 | Suzuki et al. | Aug 2021 | A1 |
20210249943 | Yamamoto | Aug 2021 | A1 |
Number | Date | Country |
---|---|---|
105151803 | Dec 2015 | CN |
106032219 | Oct 2016 | CN |
108702079 | Oct 2018 | CN |
108946032 | Dec 2018 | CN |
109080497 | Dec 2018 | CN |
110073589 | Jul 2019 | CN |
110829781 | Feb 2020 | CN |
111321375 | Jun 2020 | CN |
S61-177103 | Aug 1986 | JP |
H06-24559 | Feb 1994 | JP |
H09-19004 | Jan 1997 | JP |
2936359 | Aug 1999 | JP |
2014-165993 | Sep 2014 | JP |
2020-96514 | Jun 2020 | JP |
Entry |
---|
Chinese Office Action issued Jan. 12, 2024 during prosecution of related Chinese application No. 202111244233.2 (English language translation included). |
Chinese Office Action dated Aug. 28, 2024 during prosecution of related application No. 202111244233.2 (English-language machine translation included). |
Chinese Office Action dated Dec. 23, 2024 during prosecution of related application No. 202111244233.2 (English-language machine translation included). |
Number | Date | Country | |
---|---|---|---|
20220140762 A1 | May 2022 | US |