Abstract:
An intelligent component feeder includes a lever-powered mechanical component feed system and a memory device mounted on the mechanical feed system. The memory device has a two-terminal electrical interface, the two terminals are associated with data and data ground, respectively. The memory device, which is preferably of a non-volatile, rewritable type, contains information indicating a component ID, component Lot Number, feeder serial number, feeder type, number of feeder actuations, and a Quantity value for a reel of components mounted on the component feeder. The intelligent component feeder further includes a data connector for coupling data from the memory device to a data adapter of a placement device. The data connector comes into contact with the data adapter when the intelligent component feeder is installed on the placement device. The terminal associated with data ground is coupled with a body of said intelligent component feeder.

Description:
RELATED APPLICATIONS 
     This application claims the benefit of provisional U.S. patent application Ser. No. 60/261,308 filed on Jan. 13, 2001 in the names of the same inventors. 
    
    
     FIELD OF THE INVENTION 
     The present invention is directed to an intelligent component feeder system for use in robotic assembly devices such as pick and place machines (also known as placement machines or placement equipment). More particularly, the present invention is directed to a system for tracking the contents of a particular component feeder and enabling a host computer to recognize the feeder and its contents when the component feeder is coupled to a network to which the host computer is connected. 
     BACKGROUND OF THE INVENTION 
     Robotic assembly machines are well known in the art. Such devices, which include pick and place machines, are used, for example, in the assembly of electronic printed circuit boards (PCBs). In a conventional pick and place machine, one or more pick-up heads which are movable in X, Y, Z and rotation directions are directed to pick up electronic and similar components from pick-up stations normally supplied with components from a reel held in a component feeder containing a relatively large supply of a particular component. The force used to pick up the components is typically supplied by a vacuum air supply, a mechanical gripper or the like. Once the component is picked up, it is oriented, normally by optical means, and transported to a placement location on a substrate such as a PCB where it is placed. After all components are placed on the PCB, the PCB is normally run through a reflow oven where solder contacts are reflowed to form permanent electrical connections between pads of the PCB and various types of contact pins belonging to the electronic components. 
     Pick and place machines typically have a number of feeder stations which receive component feeders. Component feeders come in a number of well known standard widths to accommodate standard component reels. In conventional pick and place machines, a program running on a host computer which controls the machine and its operation (the controller) is manually told which feeder station has which components loaded. If an incorrect feeder is put in place and the host computer is not informed, there is generally no way for the pick and place machine to avoid placing incorrect components on the circuit board resulting in a zero manufacturing yield. 
     Conventional mechanical component feeders operate entirely mechanically. An actuator such as a rod, pin or lever driven by the machinery of the pick and place machine moves under the control of the controller of the pick and place machine. The actuator pushes against a lever of the mechanical component feeder and causes a mechanical response which results in advancing the next component onto the feeder pickup position. 
     Recently, a number of companies have introduced electronic component feeders. Such devices have their own electrical drive components, motors, microprocessors and other complex circuitry and componentry. These devices provide additional functionality over conventional mechanical component feeders but they have several drawbacks. First, because they are more complex, they are necessarily less reliable. Second, the added complexity comes at a significant cost premium to existing mechanical component feeders. Third, a customer desiring to convert to such electronic component feeders must purchase entirely new pick and place machines, control equipment, feeders and other items. Such conversions may in many cases be prohibitively expensive and do not make use of existing, relatively expensive and still operable equipment, resulting in waste. 
     When constructing complex PCBs for use in certain types of applications, e.g., airplanes, spacecraft, automobiles, and the like, it is becoming important to be able to determine long after the assembly of the PCB whether an electrical component of a specific type from a specified lot number is part of the assembled PCB. This is referred to as “traceability”. For example, when components from a particular lot are determined to have a particularly high failure rate or to contain potentially dangerous errors or defects, it would be desirable to determine which critical PCBs include the potentially defective components so that they can be readily identified, located and checked or replaced prior to failure without the need for checking or replacing all similar boards. Conventional robotic assembly equipment provides no convenient way for providing traceability, i.e., linking component lot numbers with specific assembled PCBs. 
     Accordingly, it would be desirable to provide an intelligent component feeder system which is retrofitable into existing equipment, makes use of reliable and proven mechanical feeder technology, provides traceability, and is relatively easy and inexpensive to implement. 
     BRIEF DESCRIPTION OF THE INVENTION 
     An intelligent component feeder system includes an intelligent component feeder, an adapter interface for receiving the component feeder and forming needed electrical contacts therewith, and computer software running on a computer system controlling robotic placement equipment. The intelligent component feeder is adapted from a conventional mechanical component feeder and additionally includes a nonvolatile serial memory device which can be accessed using two electrical conductors, a data line and a data ground line. One of the electrical conductors (the data line) is connected to the adapter interface via a spring-type contact so that when the component feeder is placed for use with the robotic placement equipment, an electrical contact is made to the serial memory device through the spring-type contact of the interface adapter. The second of the electrical conductors (the data ground line) is tied to the metal body of the component feeder. Electrical contact is made when the component feeder is clamped into place on the robotic placement equipment. The component feeder holds a reel of components. A bar code label is placed on the reel identifying information about the components stored thereon, such as ID, Lot Number, Quantity, feeder serial number, feeder type, number of feeder actuation, and the like. Each time that the component feeder is placed on the machine, the bar code label on its reel must be read in order to confirm a match between the reel and the data stored in the memory device. When a component reel is removed from the feeder, a new bar code label is generated reflecting any change in the quantity of components stored on the reel. The new bar code label is placed over or replaces the existing bar code label. The software is aware of each component feeder through the adapter interface and knows its feeder position, the ID of the components loaded thereon, the Lot Number of those components, approximate remaining quantity, feeder serial number, and the like. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated into and constitute a part of this specification, illustrate one or more embodiments of the present invention and, together with the detailed description, serve to explain the principles and implementations of the invention. 
     In the drawings: 
     FIG. 1 is a plan view of the layout of an intelligent component feeder in accordance with a specific embodiment of the present invention. 
     FIG. 2 is a diagram illustrating modifications made to a conventional mechanical component feeder in accordance with a specific embodiment of the present invention. 
     FIG. 3 is a diagram illustrating the mounting of a memory module feeder in accordance with a specific embodiment of the present invention. 
     FIG. 4 is a diagram illustrating electrical connections carrying the data signal from the memory module to a gripper assembly in accordance with a specific. embodiment of the present invention. 
     FIGS. 5A is an elevational drawing illustrating attachment of an intelligent component feeder to placement equipment in accordance with a specific embodiment of the present invention. 
     FIG. 5B is an elevational drawing illustrating attachment of an intelligent component feeder to placement equipment in accordance with a specific embodiment of the present invention. 
     FIG. 6A is a drawing illustrating the gripper bar and electrical contact assembly for placement equipment in accordance with a specific embodiment of the present invention. 
     FIG. 6B is a drawing illustrating the electrical contact assembly for placement equipment in accordance with a specific embodiment of the present invention. 
     FIG. 7 is a block diagram illustrating electrical contacts and connectors for placement equipment in accordance with a specific embodiment of the present invention. 
     FIGS. 8-10 are system block diagrams illustrating various configurations of placement equipment and intelligent component feeders in accordance with specific embodiments of the present invention. 
     FIGS. 11-12 are process flow diagram illustrating various methods of operation in accordance with specific embodiments of the present invention. 
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present invention are described herein in the context of an intelligent component feeder system. Those of ordinary skill in the art will realize that the following detailed description of the present invention is illustrative only and is not intended to be in any way limiting. Other embodiments of the present invention will readily suggest themselves to such skilled persons having the benefit of this disclosure. Reference will now be made in detail to implementations of the present invention as illustrated in the accompanying drawings. The same reference indicators will be used throughout the drawings and the following detailed description to refer to the same or like parts. 
     In the interest of clarity, not all of the routine features of the implementations described herein are shown and described. It will, of course, be appreciated that in the development of any such actual implementation, numerous implementation-specific decisions must be made in order to achieve the developer&#39;s specific goals, such as compliance with application- and business-related constraints, and that these specific goals will vary from one implementation to another and from one developer to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking of engineering for those of ordinary skill in the art having the benefit of this disclosure. 
     In accordance with the present invention, the components, process steps, and/or data structures may be implemented using various types of operating systems, computing platforms, computer programs, and/or general purpose machines. In addition, those of ordinary skill in the art will recognize that devices of a less general purpose nature, such as hardwired devices, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), or the like, may also be used without departing from the scope and spirit of the inventive concepts disclosed herein. 
     The Intelligent Component Feeder. 
     The intelligent component feeder is illustrated in FIGS. 1-4. FIG. 1 illustrates an overall top plan view of the intelligent component feeder  10  in accordance with a specific embodiment of the present invention. Intelligent component feeder  10  includes a portion shown at the right of FIG.  1  and labeled  12  where a component reel (not shown) is to be loaded. Intelligent component feeder  10  as shown in FIG. 1 is simply a conventional mechanical component feeder of the 8 mm width type in accordance with the prior art modified with the memory feature in accordance with a specific embodiment of the present invention. Intelligent component feeder  10  includes a gripper  14  for attaching the component feeder  10  to a gripper bar for physical attachment to placement equipment. Components are fed from the component reel with a stepping mechanism  16  powered by an external actuator (not shown) located on the placement equipment pushing against lever arm  18  prior to each pick of a component from component pick position  20 . To load or unload intelligent component feeder  10  from the gripper bar one pulls on lever  22  which releases gripper  14  from the gripper bar by rotating it counterclockwise as shown in FIG.  1 . 
     The modifications to a conventional mechanical component feeder are illustrated in FIG.  2 . Memory unit  24  is added in a location which will not mechanically interfere with component feeder operation. In accordance with a specific embodiment of the present invention the memory used is a serial-type 2-contact memory device (data and data ground) of the non-volatile multiple time writable type. For example, a suitable type of memory device is the iButton model no. DS-1996 non-volatile read/write memory having a 64-bit unique serial number and 64Kbits of memory in which data can be partially or completely overwritten. The iButton line of products is available from Dallas Semiconductor of Dallas, Texas. Those of ordinary skill in the art will now realize that other types of memory will also work, such as EEPROM (electrically eraseable programmable read only memory) and other types of non-volatile memory devices. 
     Turning now to FIG. 3, a view of the mounting arrangement for the memory unit  24  is illustrated. In accordance with this specific embodiment of the invention, memory unit  24  is sandwiched between two conductive plates  26  and  28 . Plate  26  is electrically coupled to the data line ( 27 ) of memory device  24  and plate  28  is electrically coupled to the data ground line (not shown, provided on the other side) of memory device  24 . Plate  28  is also coupled to the body of the component feeder  10  which serves as a ground return. Plate  26  is bolted to plate  28  with bolts  30  and  32  and is electrically insulated from plate  28  with insulators  34  and  36 . A conductive wire or flexible or circuit board  38  coupled to plate  26  with a conductive lug  40  carries the data signal to bolt  42  (FIG. 4) via lug  44  which is insulated from gripper  14  with insulator  46 . 
     The Interface Adapter. 
     Turning now to FIG. 5A the inside of the gripper  14  can be seen which shows how the data signal is coupled off of the component feeder  10  to a placement equipment  58 . The placement equipment  58  has typically a number of feeder stations each receiving a component feeder  10 . FIG. 5A illustrates the component feeder  10  received in one of such feeder stations. An insulator  48 , such as a film of 5 mil (0.127 mm) Mylar™ or Kapton™, for example, holds conductive contact plate  50  electrically away from the body of component feeder  10 . Gripper  14  holds onto gripper bar  52  of the placement equipment. The spring  54  (FIG. 2) biases gripper  14  closed against gripper bar  52 . The gripper  14  can be released by pulling on lever  22 . When lever  22  is released, contact plate  50  is brought into electrical contact with a spring-type contact  56  disposed on a printed circuit board  60  attached to the placement equipment  58 . A Battery Contact Type 5230 available from the Keystone Corporation may be used as may any other suitable electrical contact for spring-type contact  56 . 
     It is presently preferred to dispose spring-type contacts on the placement equipment  58  and use a flat contact plate  50  disposed on the component feeder  10  rather than to dispose the spring-type contact on the component feeder  10  to make contact with a contact plate on the placement equipment, although both approaches would work. FIG. 5B illustrates another example of the coupling between spring-type contact  56  disposed on a printed circuit board  60  and a modified contact plate  50 ′. As shown in FIG. 5B, the contact plate  50 ′ is curved to provide a contact point with the spring type contact  56 , whereby simplifying the configuration of the spring-type contact  56 . 
     By allocating the feeder ground as one of the two communication lines (i.e., data line and data ground line) of the memory device  24  (FIG.  2 ), as described above, the memory device  24  can communicate with the placement equipment  58  through only one contact via the spring-type contact  56 , as shown in FIGS. 5A and 5B. The gripper bar  52  receives the ground return from the intelligent component feeder  10 , serving as a data ground line. The gripper bar  25  may be grounded or coupled to a ground line. 
     Turning now to FIGS. 6A and 7, a printed circuit board  60  and gripper bar  52  are illustrated. Normally they would be oriented vertically as shown in FIGS. 5A or  5 B. Gripper bar  52  (FIG. 6A) is notched to provide registration for component feeders in the conventional manner. FIG. 6B illustrates another example of contact springs  56  disposed on the printed circuit board  60 , which is in accordance with the configuration shown in FIG.  5 B. In either case, contact springs  56  are positioned for contact with properly registered component feeders. Each contact spring  56  is electrically coupled to a printed circuit trace  57  on the printed circuit board  60  which leads to one of block connectors  62  as shown in FIG.  7 . Cables (not shown) couple connectors  62  with computer equipment for controlling the operation of the placement equipment. 
     System Configuration. 
     Turning now to FIG. 8, a typical configuration of a placement machine in accordance with a specific embodiment of the present invention is illustrated. In FIG. 8 placement machine  64  operates under the control of a computerized controller  66  and optionally other controllers  68  which are coupled to the placement machine  64  and to each other using various types of known network technologies, such as ArcNet, Ethernet, CanBus, and wireless networking. Controllers  68  are preferably coupled to placement machine  64  using ArcNet, controllers  68  are preferably coupled to controllers  66  using Ethernet, and controllers  66  are preferably coupled to placement machine  64  and in-line and on-line feeder trolleys using CanBus. In addition, wireless communication may be used for all or any part of the networking. For example, a wireless LAN using infrared or radio waves may be used for networking on-line feeder trolleys and/or for communication between a feeder trolley and feeders. Such wireless communication may be implemented by installing a conventional wireless modem or transceiver on each of feeder trolleys and/or feeders. 
     Intelligent Feeders  70  are mounted on feeder trolleys  72  ( 72   a ,  72   b ,  72   c ). Feeder trolleys which are being used to feed components to the placement machine  64  are known as “In-Line” trolleys and are designated “ 72   a ” in FIG.  8 . Feeder trolleys which are networked but not positioned for use are known as “On-Line” trolleys and are designated “ 72   b ” in FIG.  8 . Feeder trolleys which are not networked and not positioned for use are known as “Off-Line” trolleys and are designated “ 72   c ” in FIG.  8 . As mentioned above, wireless communication technique may be used to communicationon-line feeder trolleys and/or for communication between feeders and feeder trolleys. 
     Placement machine  64  is equipped with one or more bar code scanners  74  including a bar code scanner mounted on the pick-up head which can read bar codes disposed on the print circuit boards (PCBs) being assembled. Additional bar code scanners may also be disposed at convenient locations in the system to permit scanning of component feeder reels. Bar code label printers  76  are also disposed at one or more convenient locations in the system to provide updated bar code labels for reels to reflect updated approximate component quantities on those reels after they are demounted from a component feeder (and thus are no longer physically coupled to a memory device containing a current component count). 
     FIG. 9 is a system block diagram illustrating a typical single-line configuration in accordance with one embodiment of the present invention. As shown in FIG. 9, the system includes a line having a plurality of placement machines  64  which operate under the control of controller  66  and optional controllers  68 . The other features of the system is the same as discusses above referring to FIG.  8 . 
     FIG. 10 is a system block diagram illustrating a typical multiple-line configuration in accordance with another embodiment of the present invention. As shown in FIG. 10, the system includes a plurality of lines each having a plurality of placement machines  64 . As is well understood by those who having ordinary skill in the art, the system is expandable as desired by adding placement machines  64  to each line, and/or by adding lines and additional controllers  68  to the system as shown in FIGS. 9 and 10. 
     Methods of Operation. 
     The inventive structures and apparatus described above also make possible a number of innovative methods of operating placement equipment. For example, traceability may now be provided as illustrated in the flowchart of FIG.  11 . At block  100  each PCB to be assembled is provided with a serial number or other unique identifier. At block  102  this unique identifier is coded into a barcode or other optically or otherwise remotely scannable representation which is placed on the PCB at block  104 . At block  106  the PCB is received at the placement machine and at  108  a scanner reads a label associated with the PCB to obtain the PCB&#39;s unique ID such as a serial number. Preferably the label is of the bar code type and the scanner is a head-mounted bar code reader which moves with a pick-up head of the placement machine. The scanner may be a charge-coupled device (CCD) camera. In this way the head can locate the bar code scanner above the expected position of the label and read it. 
     Some PCBs are of the “matrix” type in that they contain a number of separable PCBs disposed in a matrix. Sometimes it is undesirable to place components on all of the members of the matrix, so it is possible to serialize all of them and select only some for assembly. It is also possible to mark a PCB as “bad” or “do not assemble” by making a mark on the label or crossing the label out. This mark or cross out can be readily detected with a bar code scanner. Thus, at block  110  the computerized controller which is coupled to the placement machine, its scanner, its head position controls, and the like, decides whether the PCB is to be assembled. 
     Where the PCB is not to be assembled (block  112 ) this is most probably due to the serial number read from the PCB correlating with a known bad serial number stored in the memory of the controller, a “bad” mark detected by a scanner, or the fact that the particular PCB is one of a matrix of a plurality of PCBs and the particular PCB has been deselected for assembly either by specifying its unique ID as deselected to the controller or by making a mark on its label which can be read by the scanner or which interferes with the scanning of the label. 
     If the PCB is to be assembled, at block  114  a record entry in a file of a memory such as a hard disk drive file associated with the controller computer is created for the particular PCB unique ID, and the PCB is assembled at block  116 . As the assembly progresses, the record is modified by adding a list of part IDs, corresponding Lot Numbers, and optionally the serial number from the memory unit of the component feeder supplying the component, its position in the trolley of component feeders being used, and potentially other information of interest. This list is derived by reading the memory device associated with the intelligent component feeder and coping the information into the memory of the controller for the placement machine (Block  118 ). Once the file is complete, it is written into a desired form at block  120 . In this way traceability is provided because the data from the file may be preserved and if a Lot Number of a particular part is ever determined to be potentially defective, the file can be searched to identify the PCB unique IDs which contain the potentially defective parts and then they can be located on that basis and checked or replaced, as warranted. 
     Additionally, the head-mounted scanner can be used to scan PCB bar codes to load jobs into the placement machine controller(s). As illustrated in FIG. 12, the PCB is loaded onto the placement machine at block  122 . At block  124  the label on the PCB (preferably a bar code label) is read to determine either a unique ID for the PCB or a program ID to be applied to the PCB. At Block  126  the assembly program corresponding to the PCB is determined and at block  128  the assembly program is loaded into one or more controllers. At block  130  the assembly program is executed. In this way, if desired, a stack of PCBs could be assembled, each having a different assembly program, indeed each could be completely or only slightly different from one another. 
     In another aspect of the invention, a program known as a “setup wizard” reads the information available at the placement machine controller to extract component IDs, component feeder locations, and number of placements per part number. Additional information may also be used. The information is then used by the assembly equipment controller to select a component feeder for the job that has at least the appropriate number of remaining components (best case) or notifies the user that there are not enough components available on in-line component feeder trolleys. Aditionally, on-line component feeders can be identified as a possible source for the missing componets as can off-line component feeders and, of course, in-line component feeders. The controller software can also plan jobs and lock out components committed to previously planned jobs so that they are not used up prior to the scheduled job start. 
     An additional feature which may now provided by the controller software allows it to correct for problems associated with the removal of a component feeder and/or its possible replacement into an “incorrect” feeder slot (e.g., different from the one it was removed from). Because the component feeder has a unique ID which can be read over the CanBus network by the controller, if the component feeder is relocated, this can easily be detected and the pick and place program automatically modified so that the PCB continues to be properly assembled despite the change in the physical position of one of the component feeders. 
     In further accordance with this concept, it is possible for the placement machine controller to create a speed-optimized assembly program picking components from desired component feeders in desired positions for maximum efficiency, then set up the machine with the component feeders in essentially random order, and still assemble the PCBs as specified by the assembly program, albeit in a non-speed-optimized fashion. Similarly, a user can simply plug the component feeders into the In-Line trolley positions in any desired or random order, then the controller can upload the identifications of the feeders and their contents. The controller software can then be used to optimize production given the user&#39;s preselection of component feeder positions using well-known conventional production optimization software. 
     In accordance with a presently preferred embodiment of the present invention, each intelligent component feeder is checked in three ways prior to each pick of a component from that feeder. First, the software of the controller checks to see if a component feeder is in fact installed at the position where the assembly program expects to pick up a part. Second, the actual part ID number is checked (this information is copied from the memory unit of the intelligent component feeder to local random access memory (RAM) for the controller so that the check takes very little time) to verify that the part that is going to be picked up is the part that the assembly program expects to pick up. Third, a feeder verification flag is checked to make sure that the flag is set to .FALSE.—a state which indicates that there are no problems with the feeder. For example, if the feeder has been removed and then replaced, it is possible that it contains a different reel of parts. In this case, the feeder verification flag is set to .TRUE. and use of that feeder requires that the reel bar code label be rescanned. 
     If any of the above-identified checks fail, then the feeder is treated as empty and an appropriate error message is generated and assembly stops before a component is picked from the feeder. If the same component is available from another In-Line feeder, the software may optionally redirect the pick to that other component feeder rather than stop the assembly process. 
     The above features make possible real-time inventory control of both component parts and assembled PCBs. Each component reel has a unique serial number in addition to a component ID and Lot Number. As component reels are purchased, they are entered into a conventional inventory tracking system. As they are loaded onto component feeders, they are scanned and the system is aware that they are In-Line or On-Line. They may simply be deleted from stock at this point, or, for finer inventory resolution, as components are used from the reels, real-time inventory control is possible by simply linking the conventional inventory control system to the CanServer software running on the placement machine system controller to capture the use information generated by the placement machine system on a real-time basis. Automatic replenishment ordering may then be performed by the inventory control system when stocks drop below predetermined thresholds. 
     Loading a component reel onto an intelligent component feeder in accordance with a specific embodiment of the present invention is performed as follows. First, the reel is obtained. Reels generally have a bar code label which identifies part ID, lot number, quantity and the like. If no bar code label is available, one is fabricated by manually entering the information into the placement machine controller and printing an appropriate bar code label on a bar code label printer. The reel is then scanned by a bar code scanner and loaded and threaded into the component feeder. The results of the scan are downloaded to the memory unit of the component feeder once it is secured to the placement equipment and is In-Line or On-Line. To unload a component reel, one prints a new bar code label for the reel reflecting the current (approximate) contents of the reel, demounts the component feeder, removes the component reel, and places the new bar code label over the existing bar code label. 
     Feeder status is preferably tracked by the placement machine controller as follows. All connected feeders (On-Line or In-Line) are given the status “Reserved”, “In Use” or “Available”. Reserved is given to feeders which are currently being loaded for the next assembly job. In Use is given to feeders currently being used for production. Available is given to feeders which are neither Reserved nor In Use. 
     While embodiments and applications of this invention have been shown and described, it would be apparent to those skilled in the art having the benefit of this disclosure that many more modifications than mentioned above are possible without departing from the inventive concepts herein. The invention, therefore, is not to be restricted except in the spirit of the appended claims.