Abstract:
An apparatus for identification of work pieces and protection of equipment used to operate on the work pieces in a computer controlled manufacturing arrangement. The equipment to be protected includes at least one receptacle for holding a work piece, and the apparatus comprises a rail and an electronic sensor mounted to the rail. The rail is shaped to generally to surround a selected portion of the equipment and is arranged to be supported proximate the equipment to deflect objects from the equipment. The electronic sensor is mounted to the rail at a location to sense a work piece in the receptacle and arranged to be coupled to the computer.

Description:
FIELD OF THE INVENTION 
     The present invention is generally directed to electronic identification of parts in an automated manufacturing arrangement, and more particularly to a rail having mounted thereon sensors for reading part identifiers. 
     BACKGROUND OF THE INVENTION 
     Automated manufacturing arrangements often use electronic sensors, for example, bar code readers, to track parts and work pieces as they move through the manufacturing process. Such arrangements also include track systems for transporting parts and work pieces from is one machine to another and unloading apparatus for removing the parts from the track system for processing by the various machines. 
     One problem that arises is that the automatic loading and unloading of parts to and from a track system sometimes interferes with the electronic sensing of the parts. Arrangements for manufacturing semiconductors typically include cassettes in which wafers are transported. The cassette loaders of some machines, for example, the wafer sorter from Kensington Labs, Inc., tilt out beyond the frame of the machine. The problems created are that the motion of the cassette loaders makes difficult the automatic reading of bar codes on cassettes. Instead of an automatic sensing of the cassette in the loader, an operator may be required to manually scan the bar codes on the cassettes once placed in the loaders. Furthermore, when the cassette loaders are tipped out from the machine they are prone to damage from accidental collisions with operators and with other equipment being moved about the factory floor. 
     Therefore, an apparatus that addresses the aforementioned problems is desirable. 
     SUMMARY OF THE INVENTION 
     In various embodiments, an apparatus is provided for identification of work pieces and protection of equipment used to operate on the work pieces in a computer controlled manufacturing arrangement. The equipment to be protected includes at least one receptacle for holding a work piece, and the apparatus comprises a rail and an electronic sensor mounted to the rail. The rail is shaped to generally to surround a selected portion of the equipment and is arranged to be supported proximate the equipment to deflect objects from the equipment. The electronic sensor is mounted to the rail at a location to sense a work piece in the receptacle and arranged to be coupled to the computer. 
     The above summary of the present invention is not intended to describe each illustrated embodiment or every implementation of the present invention. The figures and the detailed description which follow more particularly exemplify these embodiments. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention may be more completely understood upon consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, in which: 
     FIG. 1 is a block diagram of an example computer controlled manufacturing arrangement; 
     FIG. 2 is a partial perspective view of a tool to which is attached a protective rail having one or more integrated electronic sensors according to an example embodiment of the invention; 
     FIG. 3 is a top view of the tool and protective rail illustrated in FIG. 2; 
     FIG. 4 a partial front view of the protective rail in which an electronic sensor is mounted; 
     FIG. 5 is a cross-sectional view of the protective rail taken in the direction of arrow  5  of FIG. 4; 
     FIG. 6 is a cross-sectional view of the protective rail and attachment mechanism in the direction of arrow  6  of FIG. 2, in accordance with an example embodiment of the invention; and 
     FIG. 7 is a side view of an alternate support structure for the rail according to another example embodiment of the invention; 
    
    
     While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION 
     The present invention is believed to be applicable to a variety of machines used in computer controlled manufacturing arrangements, and particularly advantageous for such arrangements directed to semiconductor manufacturing. While the present invention is not so limited, an appreciation of various aspects of the invention is best gained through a discussion of various example applications described below. 
     FIG. 1 is a block diagram of an example computer controlled manufacturing arrangement  100 . The arrangement includes a central bus  102  to which various control elements are coupled. The protocol used on the bus  102  is ISIS which is available from ISIS Distributed Systems. A distributed factory system (DFS)  104  includes Workstream software that is available from Consilium, Inc., for controlling the manufacturing process of semiconductor wafers. The DFS tracks the handling of wafers by logical lots and includes a database for such tracking. 
     Tools  106   a-d  are used in the manufacturing process and are coupled to the bus  102  via equipment interface workstations  108   a-d , respectively. The workstations  108   a-d  run interface programs (not shown) that function as translators between the language of tools  106   a-d  and the ISIS protocol of the bus  102 . 
     The stockers  110   a-b  are transported on the factory floor on a track  112 , which is an overhead monorail in an example embodiment. The stockers are controlled by personal computers (not shown) that are also coupled to the bus  102 . The software for controlling movement of the stockers  110   a-b  is available from Daifuku of Japan. It will be appreciated that additional tools and stockers, along with corresponding equipment interface workstations may be included in the computer controlled manufacturing arrangement  100 . 
     FIG. 2 is a partial perspective view of a tool  202  to which is attached a protective rail  204  having one or more integrated electronic sensors  206  according to an example embodiment of the invention. In an example application of the invention, the tool  202  is a wafer sorter and includes one or more cassette loaders (abbreviated as “loader”) that are arranged to load cassettes from the stockers  110   a-d  to the tool  202  and unload cassettes from the tool to the stockers. The loaders  208  are shown in a first position in which cassettes have been loaded. In a second position, as indicated by the arrows extending from the loaders  208 , the loaders are positioned for loading cassettes from the stockers  110   a-b . In the first position, the loaders  208  are positioned for processing of the wafers by the tool  202 . When the loaders  208  are in the second position, they physically extend beyond the perimeter of the tool  202 . This extended position exposes the loader  208  to collisions with operators and various objects being moved about the factory floor. 
     The cassettes present in the loaders  208  have example bar code labels  212 . It will be appreciated that the cassettes are not individually illustrated in the interest of brevity. When the loader  208  is in the processing position as shown, the bar code label  212  on the cassette  210  is generally obscured from view from the side; in the processing position, the bar code label  212  is viewable from above. It will be appreciated that other electronically recognizable characteristics, such as a strip with a magnetic code, could be used instead of a bar code label. 
     To support automatic identification of a cassette  210  being moved into an operation, such as wafer sorting by tool  202 , a rail  204  having one or more electronic sensors  206  is attached to the tool  202 . The rail is shaped to generally conform to a portion of the perimeter of the tool  202 , and in the example embodiment, is shaped to extend from the sorter  202  beyond the projections of the loaders  208 . The shape serves to protect the loader from accidental collisions and provide support for placement of the electronic sensors  206 . The electronic sensors are coupled to an example one of the equipment interface workstations  108   a-d . When the loaders  208  are in the load position, that is tipped toward the rail  204 , the bar code labels  212  are within range of the electronic sensors  206 . Under control of the equipment interface workstation, the electronic sensor scans the cassette for identification characteristics, such as a bar code or magnetic strip. Signals generated by the sensors  206  are then provided to the equipment interface workstation for identification. 
     In an example embodiment, the electronic sensor is a SCANTEAM 3700 model bar code reader that is available from Welch Allyn. However, it will be appreciated that other applications may require other types of electronic sensors. For example, the sensors  206  may form a light curtain around the tool  202 , such that when a person or object disturbs the light curtain selected actions are automatically invoked, such as stopping the tool. 
     FIG. 3 is a top view of the tool  202  and protective rail  204  illustrated in FIG.  2 . The rail  204  is advantageously attached to the shell  252  of the tool  202  with brackets  254  that are welded to the rail  204 . Each bracket is secured to the shell  252  with a bolt that is inserted through a corresponding one of the openings  256 . The openings  256  are, for example, holes created by the manufacturer of the tool for cooling ventilation. Thus, by bolting the rail to the tool  202  using existing holes in the shell  252 , no disassembly or structural modifications to the tool are required. 
     The electronic sensors  206  are positioned in the rail  204  at locations that correspond to the respective extended positions of the loaders  208 . The dashed line blocks  256  represent the extended positions of the loaders  208 , wherein the bar codes  212  are readable by the sensors  206 . Dashed line  258  represents the cable that couples the sensors  206  to an equipment interface station, for example. 
     FIG. 4 a partial front view of the protective rail  204  in which an electronic sensor  206  is mounted. In an example embodiment, the rail  204  is formed from a stainless steel tube having an outside diameter of approximately 4″5″. The gage of the pipe should be selected to provide adequate support for the sensors  206  and protection of the tool  202  from undesirable contact with humans, or other objects. Various other materials, including plastic and other metals may also be suitable for the protective rail  204  depending upon the application. In another embodiment, the rail  204  can be padded on its outside perimeter to absorb some of the energy from the unwanted contact. 
     Forming the rail  204  from a pipe or tube is advantageous in that cabling from the sensors  206  can be threaded through the rail, whereby the cabling is both hidden and protected. It will be appreciated that the rail need not be an enclosed tube. Rather, the rail may have a generally c-shaped cross-section. 
     FIG. 5 is a cross-sectional view of the protective rail  204  taken in the direction of arrow  5  of FIG.  4 . The sensor  206  can be mounted in the rail with any one of a variety of mechanisms chosen in accordance with individual design objectives. In one embodiment, the sensor  206  may have a face plate that clips to the edges of the opening in the rail  204 . In another embodiment, a pocket or sleeve can be mounted to edges of the opening and disposed in the rail  204 . 
     The disposition and mounting of the sensor  206  relative to the protective rail  204  is influenced by design requirements. Example requirements for placement of the sensor  206  include: (1) the sensor must not obstruct movement of the object having the information to be read; (2) the sensor must be within range of the object in order to read the information; and (3) the sensor should be protected from undesired contact with people or objects. Mounting the sensor  206  within the rail  204  meets these example requirements, and in addition, provides a conduit for the cabling that couples the sensors to the electronic interface. 
     FIG. 6 is a cross-sectional view of the protective rail  204  and attachment mechanism in the direction of arrow  6  of FIG. 2, in accordance with an example embodiment of the invention. The attachment mechanism includes a bracket  272  and a bolt arrangement  274 . The bracket  272  is welded to the rail  204 , for example, and includes an opening  276  that is sized to accommodate the bolt arrangement  274 . The bolt arrangement  274  includes, for example, a bolt  278  and an anchor  280 . The anchor includes wing elements  282  and  284 , for example, that are pivotably attached to a nut or threaded sleeve. The example bolt arrangement is also sometimes referred to as a toggle bolt, whose usage is well understood for various applications. It will be appreciated that other bolt arrangements may also be suitable, for example, a nut and bolt arrangement or a bolt and cam arrangement. In yet another embodiment, the rail  204  may be attached to the tool  204  with clamps. 
     Selection of the type of mechanism used to attach the rail  204  to the tool  202  will depend upon the particular tool and when/who attaches the rail. For example, in after market applications where the user of a tool is installing the rail  204 , it will be desirable to use a toggle bolt arrangement, or a similarly suited mechanism to permit attachment of the rail without modification or disassembly of the supporting structure of the tool. However, if the tool manufacturer is attaching the rail, more permanent attachment mechanisms may be suitable. For example, the manufacturer could permanently or semi-permanently attach the rail to the tool support structure, such as by welding or with hidden clamps. 
     FIG. 7 is a side view of an alternate support structure for the rail  204  according to another example embodiment of the invention. Generally, the rail  204  is supported by vertical support members  302  and  304 . Such an arrangement is intended to be free-standing relative to the tool  202  which the rail  204  is intended to protect. The free-standing structure may be especially suitable for after market applications where the tool has no structure available to which to attach the rail without disassembling the tool. 
     In an example embodiment, each support member may be a steel pipe having at least one threaded end  306 . A support bracket  308  is welded to or formed with the rail  204  and has a threaded female member to engage the threaded end  306  of the support member  302 . This arrangement provides a mechanism for easily adjusting the height of the rail. Height adjustment may be important for aligning the electronic sensors  206  with the articles to be scanned. In other example embodiments, the support members  302  and  304  may be height adjustable by way of clamps, or alternatively, holes bored in the support members near the sleeve  310  with pins inserted in the holes to adjust the height. It will be appreciated that the height of the rail  204  may be set according to commonly known ergonomic standards, for example standards associated with semiconductor tools. 
     The support members  302  and  304  are secured to a base plate  322 , for example with metal sleeves  334  and  336  which are welded to the plate. The base plate  332  can be secured to the floor  338  by anchor bolts  340 , for example. In other applications it may be suitable to anchor the support members  302  and  304  directly to the floor. 
     Those skilled in the art will appreciate that other support structures may be suitable depending upon the manufacturing environment and structure that surrounds the tool. For example, the rail  204  may be supported by a wall mount arrangement if there is a suitable wall close to the tool. 
     Alternatively, the rail  204  may be part of a conventional gate arrangement (not shown) wherein the rail  204  can be swung away from the tool  202 . Such a gate arrangement may be desirable to permit servicing the tool. Those skilled in the art will appreciate that the rail  204  may also have a vertical support provided opposite the hinged end. In addition, or alternatively, the rail may also be secured to the tool. 
     As noted above, the present invention is applicable to a number of different machines in computer controlled manufacturing arrangement. Accordingly, the present invention should not be considered limited to the particular examples described above, but rather should be understood to cover all aspects of the invention as fairly set out in the attached claims. Various modifications, equivalent structures, as well as numerous structures to which the present invention may be applicable will be readily apparent to those of skill in the art upon review of the present specification. The claims are intended to cover such modifications and devices.