HANDLING OF STACKED SUBSTRATES
A pneumatic device for transporting a substrate during a manufacturing operation is described. The pneumatic device can include multiple suction assemblies for securely coupling the substrate to the pneumatic device. The vertical position of the suction assemblies can be varied so that when vacuum is applied through the suction assemblies to the substrate, the substrate is in a bent configuration when secured to the pneumatic device. When the pneumatic device is used to lift the substrate off a stack of other substrates, the bending of the substrate reduces the surface area contact and likelihood of inadvertently removing additional substrates from the stack of substrates.
In certain types of manufacturing operations, lifting a sheet-like component from a stack of similar components can be problematic on account of the sheet-like components having a tendency of sticking together. When the components stick together a traditional vacuum-based manipulating tool such as a pick and place can remove too many of the components. In some cases, the additional components can fall to the floor while the manipulating tool is moving the components. Consequently, a reliable way of removing a single sheet-like component from a stack of similar sheet-like components is desired.
SUMMARYThis disclosure describes various embodiments that relate to the use of a pneumatic device for reliably transporting substrates from one area to another.
A pneumatic device for lifting, moving and releasing a substrate is disclosed. The pneumatic device is configured to lift the substrate using multiple suction assemblies. The suction assemblies can be pressed against a surface of the substrate to secure the suction assemblies to the surface thereof. In some embodiments, one or more of the suction assemblies can include a pneumatic tube for drawing air through an opening in the suction assembly. In this way, the suction assemblies that include pneumatic tubes can be attached by vacuum to the substrate.
The suction assemblies can be spring-loaded suction assemblies configured to engage the substrate with varying amounts of force. The force variation can be achieved by arranging the suction assemblies so that a first group of the spring-loaded suction assemblies contacts the substrate after a second group of the spring-loaded suction assemblies. This causes springs of the second group to be compressed farther than the springs of the first group, thereby resulting in a greater amount of force being applied by the springs of the second group. When the substrate is flexible enough to bend, this variation in force causes the regions contacted by the second group of spring-loaded suction assemblies to be forced farther away from the pneumatic device than the rest of the substrate. In this way, the substrate is placed in a bent state.
In some embodiments, the suction assemblies can be positioned by and secured within openings defined by a substantially planar plate. The suction assemblies can include vertical adjustment features that allow the vertical position of the suction assembly with respect to the substantially planar plate to be shifted to achieve a desired position.
In some embodiments, a curved plate can be utilized to support the suction assemblies. Instead of altering the vertical position of the suction assemblies with respect to the plate, the curvature of the plate can be used to define the amount of vertical standoff there is between each of the suction assemblies.
In some embodiments, one or more the spring-loaded suction assemblies in the second group can be replaced by pushing assemblies that do not include any type of suction element but are operable to push a central portion of the substrate away from the pneumatic device while the substrate is being held by the pneumatic device.
The bent state of the substrate, achieved by securing the pneumatic device to the substrate, reduces the amount of surface area contact between the substrate and any other components beneath it. This reduction in surface area contact can reduce the likelihood of the substrate remaining temporarily coupled to any other components positioned beneath it. Examples of forces that could cause a temporary coupling dependent on surface area contact include static friction and condensation.
Other aspects and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the described embodiments.
The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural assemblies, and in which:
Other aspects and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the described embodiments.
DETAILED DESCRIPTIONIn the following detailed description, references are made to the accompanying drawings, which form a part of the description and in which are shown, by way of illustration, specific embodiments in accordance with the described embodiments. Although these embodiments are described in sufficient detail to enable one skilled in the art to practice them, it is understood that these examples are not limiting; other embodiments may be used, and changes may be made without departing from the spirit and scope of the described embodiments.
During a process for manufacturing solar cells, component manipulation can be carried out by many different types of devices. Such devices include pick and place robots, conveyors, stackers, unstackers and pneumatic devices. Pneumatic devices are commonly used to manipulate components and can be adapted to maneuver and reorient the components during manufacturing operations. The pneumatic devices can include an attachment feature that can take the form of suction assemblies. The suction assembly can define a channel through which suction can be applied until the component is firmly attached to the portion of the pneumatic device that defines one end of the channel, at which point negative pressure generated by the suction maintains the component securely against the pneumatic device. Once the pneumatic device has finished transporting the component to its intended destination, the suction generated by the pneumatic device can be turned off allowing the component to be released from the pneumatic device.
Unfortunately, conventional pneumatic devices have a number of limitations. In particular, because some pneumatic devices often attach to a top surface of a component, the bottom surface of the component remains unsupported while the component is transported from one location to another. For this reason, any item temporarily coupled to the bottom of the component is subjected to gravitational forces as well as any additional forces generated by movement of the pneumatic device. This can be problematic when a pneumatic device is used to remove a sheet-like component from a stack of similar sheet-like components. A sheet-like component can be any substrate having substantially larger top and bottom surfaces than lateral surfaces. On account of the large surface area contact between the sheet-like components of the stack, static friction, condensation and/or other surface area dependent phenomenon can temporarily couple the top component to one or more of the components beneath it. When the pneumatic device lifts the top component off the stack, static friction or condensation can cause one or more of the other similar components below it to be transported along with the top component. In some cases, the loose coupling can fail while the top component is being manipulated, causing the other component(s) to separate from the top component and drop to the floor. Alternatively, the other components could stay coupled together and result in moving more components than necessary to a subsequent step in the manufacturing operation. Either result would be undesirable.
One solution to the aforementioned problem is to utilize a pneumatic device configured to draw air through multiple suction assemblies. The suction assemblies can be distributed across the pneumatic device so that suction, generated by a pneumatic system of the pneumatic device such as an air mover, is applied to multiple locations along a top component located atop a stack of other components. When the pneumatic device engages the top component, one or more of the suction assemblies can be configured to exert a force upon a central portion of the component while two or more of the suction assemblies can be configured to exert a different amount of force upon peripheral portions of the top component. The differential force exerted by the suction assemblies can cause the peripheral portions of the top component to bend away from the stack of other components. In this way, temporary couplings between the top component and the stack of components beneath can be severed. In some embodiments, one or more of the suction assemblies can take the form of a conventional suction cup or plunger, operable to attach to and retain a firm grip on the top component without the need for pneumatic suction.
One specific application where this type of pneumatic device can be employed is in removing a silicon wafer or solar cell from a stack of other solar cells. Because the solar cells are quite thin, commonly on the order of between 100 and 500 microns, bending the solar cells is quite feasible. Generally, the differential forces applied by the suction assemblies need only lift the periphery of the cell high enough to separate the periphery from the solar cells beneath it. In some embodiments, lifting the periphery about 1-2 mm above the center can be sufficient to obtain positive results. It should be noted that in the following portions of the detailed description that the term substrate is used to refer to the sheet-like components depicted in this disclosure. The term substrate is used to include the silicon substrate upon which the solar cell is based. The term can also include refer to any intermediate manufacturing state achieved by the silicon substrate as it is becomes a solar cell. It should also be noted that he described embodiments could be applied for destacking other sheet-like components, such as, e.g., different types of wafers or sub solar cells without departing from the spirit and scope of the disclosure.
These and other embodiments are discussed below with reference to
Referring now to the drawing figures,
At 704, pneumatic tubes apply suction to the substrate through suction assemblies of the first group, thereby further strengthening the coupling between the pneumatic device and the top substrate. In some embodiments, the second group suction assemblies can be configured to receive positive pressure to apply additional force to a central portion of the substrate. In some embodiments, this added force can be used to tune the amount of bending in the substrate. For example, if a computer vision system were to identify a substrate clinging to the bottom of a substrate held by the pneumatic device, positive pressure could be delivered through the second group of suction assemblies in order to encourage separation of the clinging substrate. In some embodiments, a configuration capable of concurrently applying suction through the second group of suction assemblies and positive pressure through the first group of suction assemblies could include two different pneumatic systems. A pneumatic system can take the form of a compressor or air mover. In some embodiments, the pneumatic system attached to the first group of suction assemblies could be capable of only applying positive pressure through the first group of suction assemblies while the pneumatic system attached to the second group of suction assemblies could be configured to apply positive pressure and suction.
At 706, the pneumatic device is depicted as it is moving away from the stack of substrates and lifting the top substrate off the stack of substrates. As the pneumatic device moves away from the stack of substrates, the first group of suction assemblies would lift a periphery of the top substrate away from the stack of substrates, thereby beginning to bend the periphery of the top substrate away from the stack of remaining substrates. The speed at which the pneumatic device moves away from the stack can be modulated to discourage adhesion between the top substrate and the substrates beneath it. For example, a slower speed can be used until separation of the substrate from the stack is likely. It should be noted that in some embodiments modulation of speed would be unnecessary on account of the substantial separation of the substrate from the stack of substrates being sufficient to prevent any likelihood of unintentional coupling between the secured substrate and the remaining stack of substrates.
At 708, after the pneumatic device has moved the substrate to its new location, the vacuum suction applied through the pneumatic tubes can be removed so that the substrate can be released from the pneumatic device. In some embodiments, instead of simply ceasing the application of suction through the suction assemblies, pressure moving through the pneumatic tubes can be reversed so that positive pressure is applied to the substrate. This can be helpful in situations where the substrate could remain attached due to the coupling generated by the suction cups alone. Even when release is not necessary to release the substrate from the pneumatic device, the positive pressure can also help to make the release of the substrate more rapid so that the handling operation can be carried out more quickly. It should be noted that the springs disposed within the suction assemblies can help to cushion any force resulting from the substrate contacting another support surface just prior to release. In other embodiments, the substrate can be released and dropped a short distance before contacting a support surface.
The various aspects, embodiments, implementations or features of the described embodiments can be used separately or in any combination. Various aspects of the described embodiments can be implemented by software, hardware or a combination of hardware and software. For example, in some embodiments, a processor executing computer code can be configured to direct the actions taken by the pneumatic device. As described above, the actions taken can include applying suction to pick up the substrate, continuing to apply suction while transporting the substrate and ceasing the use of suction to release the substrate from the pneumatic device. In this way, the various installation steps described herein could therefore be carried out by a computing platform with instructions executed by the processor and carried out by machinery similar to that illustrated in
Representative applications of methods and apparatus according to the present application are described above. These examples are being provided solely to add context and aid in the understanding of the described embodiments. It will thus be apparent to one skilled in the art that the described embodiments may be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order to avoid unnecessarily obscuring the described embodiments. Other applications are possible, such that the following examples should not be taken as limiting.
The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of specific embodiments are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the described embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.
Claims
1. A pneumatic device, comprising:
- a support structure; and
- a plurality of spring-loaded suction assemblies coupled to the support structure, the plurality of spring-loaded suction assemblies comprising: a first group of two or more spring-loaded suction assemblies extending a first distance from a surface of the support structure, and a second group of one or more spring-loaded suction assemblies extending a second distance from the surface of the support structure, the second distance being greater than the first distance.
2. The pneumatic device of claim 1, wherein each spring-loaded suction assembly of the plurality of spring-loaded suction assemblies includes a suction cup at a distal end of the spring-loaded suction assembly.
3. The pneumatic device of claim 2, wherein the suction cups associated with the first group have a different design than the suction cups associated with the second group.
4. The pneumatic device of claim 1, wherein the first group of two or more spring-loaded suction assemblies is arranged in a pattern that defines a polygon and wherein the second group of one or more spring-loaded suction assemblies is positioned within the polygon.
5. The pneumatic device of claim 1, wherein the second group is arranged along a line and wherein each of the spring-loaded suction assemblies of the first group is offset from the line by substantially the same distance.
6. The pneumatic device of claim 1, further comprising an air mover.
7. The pneumatic device of claim 6, wherein each suction assembly of the first group of suction assemblies includes a pneumatic tube configured to receive positive or negative pressure from the air mover.
8. The pneumatic device of claim 1, wherein each spring-loaded suction assembly comprises an internal spring.
9. A method of lifting a substrate off of a stack of substrates, the method comprising:
- engaging a peripheral portion of the substrate with a first group of suction assemblies of a pneumatic device;
- engaging a central portion of the substrate with a second group of suction assemblies of the pneumatic device;
- bending the peripheral portion of the substrate away from the stack of substrates using the first group of suction assemblies while the second group of suction assemblies keeps the central portion of the substrate in contact with the stack of substrates; and
- lifting the substrate off of the stack of substrates after bending the peripheral portion.
10. The method of claim 9, wherein lifting the substrate comprises maintaining the bend in the substrate until the substrate is fully separated from the stack of substrates.
11. The method of claim 9, wherein bending the peripheral portion of the substrate away from the stack of substrates comprises bending the substrate about a line of maximum deflection.
12. The method of claim 9, wherein engaging the peripheral portion of the substrate comprises applying vacuum suction to the peripheral portion through the first group of suction assemblies.
13. The method of claim 12, wherein engaging the central portion of the substrate does not include applying vacuum suction through the second group of suction assemblies.
14. The method of claim 12, further comprising releasing the substrate from the pneumatic device by applying positive pressure to the substrate through the first group of suction assemblies.
15. The method of claim 9, further comprising directing air between the substrate and the stack of substrates to help separate the substrate from the stack of substrates.
16. The method of claim 9, wherein engaging the central portion of the substrate comprises positioning the second group of suction assemblies along a line of maximum deflection of the substrate.
17. A pneumatic device, comprising:
- a support structure;
- a plurality of suction assemblies coupled to the support structure;
- a pushing assembly coupled to the support structure and extending farther away from the support structure than two or more of the plurality of suction assemblies; and
- an air mover configured to drive air through and draw air into the plurality of suction assemblies.
18. The pneumatic device of claim 17, wherein the pushing member is a spring-loaded suction assembly.
19. The pneumatic device of claim 17, wherein the pushing assembly comprises a pushing member configured to engage a substrate with a convex surface.
20. The pneumatic device of claim 19, wherein the first group of suction assemblies is arranged along a periphery of the substantially planar support structure.
Type: Application
Filed: Sep 2, 2016
Publication Date: Mar 8, 2018
Inventor: Valeriy S. Litvak (Los Gatos, CA)
Application Number: 15/256,357