Patent Application
20140110225
The present subject matter relates generally to the field of thin film vapor deposition systems, wherein a thin film layer, such as a semiconductor layer, is deposited on a substrate conveyed through the system. More particularly, the present subject matter is related to a geared conveyor system used to move the substrates through a vapor deposition system.
Production of thin film photovoltaic (PV) modules (also referred to as “solar panels”) typically involves conveyance of a substrate, such as a glass panel, into and out of a vapor deposition chamber wherein a thin film layer (generally recognized in the industry as less than 10 μm) of a semiconductor material, such as cadmium telluride (CdTe) is deposited onto the surface of the substrate. The deposition process may be any known process, such as a close space sublimation (CSS) system, a chemical vapor deposition (CVD) system, or physical vapor deposition (PVD) system.
Solar energy systems using CdTe PV modules are generally recognized as the most cost efficient of the commercially available systems in terms of cost per watt of power generated. However, the advantages of CdTe not withstanding, sustainable commercial exploitation and acceptance of solar power as a supplemental or primary source of industrial or residential power depends on the ability to produce efficient PV modules on a large scale and in a cost effective manner. In this regard, it is highly desirable to reduce down-time of the vapor deposition system used in production of the PV modules.
Typically, various types of conveyors are utilized to move the PV module substrates through the vapor deposition system. Components of the conveyors may be exposed to the source material vapors, which can condense into a detrimental buildup of the source material on the conveyor components. In this situation, the conveyor components need to be removed and cleaned or replaced with clean components. The conveyor components may also need to be removed for periodic maintenance, replacement, or other procedures requiring shutdown of the system. Reduction of system downtime associated with conveyor maintenance, replacement, or other reasons is an ongoing concern.
U.S. Patent Publication No. 2011/0155063 (Little et. al), filed on Dec. 30, 2011 and entitled “Conveyor Assembly with Removable Rollers for a Vapor Deposition System,” the disclosure of which is hereby incorporated by reference herein for all purposes, describes a conveyor assembly that includes removable rollers, thereby allowing for a reduction in the downtime associated with component replacement and maintenance. However, while this conveyor assembly provides significant advantages over other prior art conveyors, it is still believed that the overall operation of the conveyor assembly can be improved.
Accordingly, there still exists a need for an improved conveyor assembly particularly suited for conveyance of substrates conveyed through a vapor deposition that reduces downtime associated with component replacement and maintenance. The present subject matter relates to a conveyor assembly that serves this purpose.
Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
In one aspect, the present subject matter is directed to a conveyor assembly for conveying substrates through a vapor deposition system. The conveyor assembly may generally include a first carriage rail disposed on a drive side of the conveyor assembly and a second carriage rail disposed on an opposite side of the conveyor assembly. Each of the carriage rails may define a plurality of roller positions, with a plurality of the roller positions on the first carriage rail being configured as drive positions. The conveyor assembly may also include a drive pulley positioned at each drive position. Each drive pulley may be configured to rotationally drive a drive device. In addition, the conveyor assembly may include a plurality of rollers extending between the carriage rails at the roller positions. The rollers disposed at the drive positions may be configured to engage the drive devices.
In another aspect, the present subject matter is directed to a vapor deposition module for use in conveying a substrate through a vapor deposition system wherein a source material is converted to a vapor and deposited onto a surface of the substrate. The vapor deposition module may include a housing and a conveyor assembly operably configured within the housing to convey a substrate through the housing. The conveyor assembly may generally include a first carriage rail disposed on a drive side of the conveyor assembly and a second carriage rail disposed on an opposite side of the conveyor assembly. Each of the carriage rails may define a plurality of roller positions, with a plurality of the roller positions on the first carriage rail being configured as drive positions. The conveyor assembly may also include a drive pulley positioned at each drive position. Each drive pulley may be configured to rotationally drive a drive device. In addition, the conveyor assembly may include a plurality of rollers extending between the carriage rails at the roller positions. The rollers disposed at the drive positions may be configured to engage the drive devices.
In a further aspect, the present subject matter is directed to a vapor deposition system configured for converting to vapor and depositing a source material onto a surface of a substrate conveyed through the system. The vapor deposition system may include a plurality of individual, longitudinally aligned modules. The modules may define a conveyance path for the substrates conveyed through the system and each module may include a housing and a conveyor assembly operably configured within the housing to convey the substrates through the housing. The conveyor assembly may generally include a first carriage rail disposed on a drive side of the conveyor assembly and a second carriage rail disposed on an opposite side of the conveyor assembly. Each of the carriage rails may define a plurality of roller positions, with a plurality of the roller positions on the first carriage rail being configured as drive positions. The conveyor assembly may also include a drive pulley positioned at each drive position. Each drive pulley may be configured to rotationally drive a drive device. In addition, the conveyor assembly may include a plurality of rollers extending between the carriage rails at the roller positions. The rollers disposed at the drive positions may be configured to engage the drive devices.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
A full and enabling disclosure of the present invention, including the best mode thereof, is set forth in the specification, which makes reference to the appended drawings, in which:
Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment, can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention encompass such modifications and variations as come within the scope of the appended claims and their equivalents.
In general, the present subject matter is directed to a conveyor assembly used to move substrates through a vapor deposition system. In particular, the present subject matter disclosed a conveyor assembly including geared, removable rollers. Thus, unlike the conveyor assembly disclosed in U.S. Patent Publication No. 2011/0155063 (described above) that includes friction-driven, removable rollers, the rollers of the disclosed conveyor assembly are driven via meshing gears. Such a direct-drive configuration may allow for an exact, constant relationship to be established between the rotational speed of the drive unit driving the conveyor assembly and the actual or final rotational speed of the rollers, thereby providing for precise control of the speed through which substrates may be conveyed through the vapor deposition system. Accurate speed control of the rollers may greatly enhance the overall operation of the vapor deposition system, such as by ensuring a constant thickness of the source material deposited onto the substrates. Moreover, friction-driven rollers may often get struck, which can lead to scratching of the substrate as it moves over the stuck roller(s). However, the configuration described herein provides for continuous rotation of the rollers, thereby preventing scratching of the substrate.
Referring now to the drawings,
The system 10 is generally configured for deposition of a thin film layer on a photovoltaic (PV) module substrate 14 (referred to hereafter as simply “substrate 14”). The thin film may be, for example, a film layer of cadmium telluride (CdTe). As indicated above, it is generally recognized in the art that a “thin” film layer on a PV module substrate is generally less than about 10 microns (μm). It should be appreciated that the conveyor assemblies 100 are not limited to use in the system 10 illustrated in
As shown in
The vapor deposition apparatus 60 may take on various configurations and operating principles within the scope and spirit of the present subject matter and is generally configured for vapor deposition of a source material, such as CdTe, as a thin film on the PV module substrates 14. In the embodiment of the system 10 shown in
The vacuum chamber 12 also includes a plurality of interconnected cool-down modules 20 within the vacuum chamber 12 downstream of the vapor deposition apparatus 60. The cool-down modules 20 define a cool-down section within the vacuum chamber 12 in which the substrates 14 having the thin film of source material deposited thereon are allowed to cool at a controlled cool-down rate prior to the substrates 14 being removed from the system 10. Each of the modules 20 may include a forced cooling system wherein a cooling medium, such as chilled water, refrigerant, or other medium is pumped through cooling coils configured with the modules 20.
Additionally, in the illustrated embodiment of the system 10, at least one post-heat module 22 is located immediately downstream of the vapor deposition apparatus 60 and before the cool-down modules 20. As the leading section of a substrate 14 is conveyed out of the vapor deposition apparatus 60, it moves into the post-heat module 22, which maintains the temperature of the substrate 14 at essentially the same temperature as the remaining portion of the substrate 14 within the vapor deposition apparatus 60. In this way, the leading section of the substrate 14 is not allowed to cool while the trailing section of the substrate 14 is still within the vapor deposition apparatus 60. If the leading section of a substrate 14 were allowed to cool as it exited the apparatus 60, a non-uniform temperature would be generated longitudinally along the substrate 14. This condition could result in the substrate breaking from thermal stress.
As diagrammatically illustrated in
Still referring to
An exit vacuum lock station is configured downstream of the last cool-down module 20, and operates essentially in reverse of the entry vacuum lock station described above. For example, the exit vacuum lock station may include an exit buffer module 42 and a downstream exit lock module 44. Sequentially operated valves 34 are disposed between the buffer module 42 and the last one of the cool-down modules 20, between the buffer module 42 and the exit lock module 44, and between the exit lock module 44 and an exit conveyor module 46. A fine vacuum pump 38 is configured with the exit buffer module 42, and a rough vacuum pump 32 is configured with the exit lock module 44. The pumps 32, 38 and valves 34 are sequentially operated to move the substrates 14 out of the vacuum chamber 12 in a step-wise fashion without loss of vacuum condition within the vacuum chamber 12.
Additionally, the system 10 also includes a coordinated conveyor system configured to move the substrates 14 into, through, and out of the vacuum chamber 12. In the illustrated embodiment, this conveyor system includes a plurality of individually controlled conveyor assemblies 100, with each of the various modules in the system 10 including one or more of the conveyor assemblies 100. All or any combination of these conveyor assemblies 100 may be configured in accordance with aspects of the present subject matter, as will be described in greater detail below. The respective conveyor assemblies 100 include conveyor drive units 102 that control the conveyance rate of substrates 14 through the respective modules.
As described above, each of the various modules and respective conveyors in the system 10 are independently controlled to perform a particular function. For such control, each of the individual modules may have an associated independent controller 50 configured therewith to control the individual functions of the respective module, including the conveyance rate of the conveyor assemblies 100. The plurality of controllers 50 may, in turn, be in communication with a central system controller 52, as illustrated in
Referring still to
Referring now to
The respective conveyor assemblies 100 include at least one drive unit 102 configured with the modules 138. In the embodiment illustrated in
The conveyor assemblies 100 are not limited to any particular type or configuration of drive unit 102. In this regard, the drive unit 102 is generically depicted in the figures. In a particular embodiment described herein, the drive unit 102 may be a motor that serves to drive a drive belt 126 (
Referring to
The first and second carriage rails 104, 106 may be formed of any suitable material configured for the particular type of environment in which the conveyor assembly 100 is intended. In an embodiment wherein the conveyor assemblies 100 are used in a relatively high temperature vacuum deposition system 10, as described above with respect to
Referring particularly to
The wheels 114, 116 may be disposed relative to the bottom of the respective recesses 110 so as to define a cradle for the rollers 120, which may allow for the rollers 120 to be supported on the wheels 114, 116 without contacting the first and second carriage rails 104, 106. For example, as particularly shown in
As particularly shown in
Referring to
In addition, as particularly shown in
It should be appreciated that the dimensions of the drive and roller gears 172, 174 and/or the dimensions of the wheels 114, 116 may be selected such that, when each drive gear 172 is rotationally engaged with its corresponding roller gear 174, the rollers 120 may be configured to remain in contact with and be rotationally supported by the wheels 114, 116 disposed at each roller position. For example, as shown in
It should also be appreciated that, as an alternative to the geared configuration, the rollers 120 may be mechanically driven using any other suitable mechanical drive device known in the art.
As indicated above, it should be appreciated that the drive units 102 may be configured to drive the belt 126 in its endless-loop path using any suitable mechanical configuration. For example, the drive unit 102 may include a motor that is rotationally engaged with one or more of the drive pulleys 115 through any suitable gearing arrangement. In an alternate embodiment, a separate drive pulley may be provided anywhere along the path of the belt 126 to drive the belt in its endless-loop path. It should be readily appreciated that various suitable drive arrangements are within the scope and spirit of the present subject matter for this purpose.
Additionally, as mentioned above with respect to the discussion of
As particularly shown in
Although not depicted herein, it should be appreciated that any manner of structure may be disposed along the top surface of the respective rails 104, 106 to prevent inadvertent ejection of the rollers 120 from the respective roller positions 108. The structure may be, for example, shielding, a lock bar, or any other type of readily removable structure. If such structure is provided, then the structure would need to be removed from the rails 104, 106 for subsequent removal of the rollers 120.
As mentioned above, the present subject matter also encompasses any manner of vapor deposition modules for use in conveying a substrate 14 through a vapor deposition system, such as the system 10 shown in
Similarly, the present subject matter also encompasses a vapor deposition system, such as the system 10 described above with respect to
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
