Abstract:
Loading a component carrier strip carrying a series of discrete components to be assembled onto circuit boards is accomplished by first inserting a free end of the component carrier strip into a slot defined by a housing (e.g., a blind slot). Then, with the component carrier strip positioned in the slot, a physical orientation of a component marking that indicates polarity is indicated to a component placement machine, e.g., by manipulating a switch, or scanning a barcode. Thereafter, the component carrier strip is removed from the slot and loaded into the component placement machine, e.g., by splicing a leading edge of the component carrier strip onto a trailing edge of a previously loaded component carrier strip.

Description:
TECHNICAL FIELD 
       [0001]    This invention relates to properly orienting discrete electronic components for assembly to circuit boards. 
       BACKGROUND 
       [0002]    Component placement machines may be used to efficiently and cost effectively manufacture circuit boards containing electronic components. A variety of methods can be employed to provide electronic components to the placement machine including the use of component carrier strips spooled onto a reel and fed into the placement machine and component carrier strips fed from a fan-fold package (ammunition pack). Although component carrier strips typically include 1000&#39;s or more of components, they are typically of the same type and are usually intended to have similar electrical characteristics. A wide, assortment of components are presently available from various of manufacturers and include, for example, resistors, inductors, capacitors, transistors, and integrated circuit chips. 
         [0003]    During the manufacture of a circuit board, one or more pick heads of the placement machine can remove components from one or more reels for subsequent placement onto the circuit board. The efficiency of the component placement machine can be improved by splicing a second carrier strip onto the tail end of the first carrier strip such that upon removing the last component of the first carrier strip, the part placement machine can proceed onto the second carrier strip with little or no interruption. 
         [0004]    Although the use of component placement machines may improve efficiency and reliability in the manufacture of circuit boards, manufacturing defects may still occur due to operator or machine error. One type of defect is the improper orientation of an electronic component on the circuit board. While reversing the orientation of some components, such as resistors, has no effect on the function of the component, other components, such as diodes and certain capacitors, must be oriented correctly for proper operation of the part. In the case of most electrolytic capacitors, the proper orientation is indicated by a polarity mark on the packaging. Other types of devices may include marks to indicate proper orientation without respect to a particular polarity requirement, such as transistors and integrated circuit chips. 
         [0005]    While the orientation of the components with respect to the leading edge of the carrier strip is intended to be consistent for a given component manufacturer, the orientation may vary from one manufacturer to another. In addition, some component strips are packaged in fan-fold boxes having a first edge at one end of the box and a second edge at the other end of the box. For this type of packaging, the side of the box that is opened first determines the leading edge of the component strip and thus, the orientation of the components with respect to the leading edge. In other words, the orientation of the components will depend on what side of the box is opened first. Therefore, splicing a second component strip on to a first component strip may lead to a change in orientation of the components fed into the placement machine. 
       SUMMARY 
       [0006]    Manufacturing defects related to improper orientation of electronic components may be reduced or eliminated by applying the technique disclosed within this specification in the use of the invention. 
         [0007]    In one aspect, loading a component carrier strip carrying a series of discrete components to be assembled onto circuit boards is accomplished by first inserting a free end of the component carrier strip into a slot defined by a housing (e.g., a blind slot). Then, with the component carrier strip positioned in the slot, a physical orientation of a component marking that indicates polarity is indicated to a component placement machine, e.g., by manipulating a switch, or scanning a barcode. Thereafter, the component carrier strip is removed from the slot and loaded into the component placement machine, e.g., by splicing a leading edge of the component carrier strip onto a trailing edge of a previously loaded component carrier strip. 
         [0008]    In another aspect, a polarity indicating apparatus includes a housing defining a slot sized to receive a free end of a carrier strip carrying a series of discrete electronic components for assembly onto circuit boards. The slot is of a sufficient length to span a distal one of the electronic components carried by the strip. The slot may be a feature having four faces such that one is perpendicular to the remaining three (e.g., a blind slot). Multiple visual component orientation indicators are also included. Each corresponds to a visual orientation of an electronic component within the slot and also corresponds to one of a discrete set of component orientation inputs available to an operator of an electronic component placement machine associated with the polarity indicating apparatus. The input may be provided to a hand-held device, a computer, or to the component placement machine. 
         [0009]    Some implementations may include at least one manipulable switch operable to provide the input from the operator reflecting the orientation of the polarity mark with respect to the slot. Some implementations may include a touch-screen or a keyboard operable to provide the input from the operator reflecting the orientation of the polarity mark with respect to the slot. 
         [0010]    In one aspect, loading a component carrier strip carrying a series of discrete axial components to be assembled onto circuit boards is accomplished by loading a component carrier strip into a component placement machine, e.g., by splicing a leading edge of the component carrier strip onto a trailing edge of a previously loaded component carrier strip. Then, with the component carrier strip positioned on the component placement machine, a physical orientation of a component marking that indicates polarity is indicated to the component placement machine. In some implementations, the physical orientation of the component marking is indicated by initiating a cycle-stop to allow the operator to correct the orientation. In some implementations, indicating the physical orientation may include scanning a barcode or manipulating a switch. 
         [0011]    The details of one or more embodiments of the invention arc set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0012]      FIG. 1  illustrates a component reel. 
           [0013]      FIGS. 2A-C  illustrate a component strip in a fan-fold box. 
           [0014]      FIGS. 3A and 3B  illustrate a plan view of the component carrier strip. 
           [0015]      FIGS. 4A and 4B  are illustrations of an embodiment including four press-button switches. 
           [0016]      FIGS. 5A and 5B  are side and top views, respectively, illustrating the insertion of a leading edge of a component strip into a blind slot. 
           [0017]      FIG. 6  is a flow-chart for loading a component carrier strip. 
           [0018]      FIG. 7  is a flow-chart for loading a component carrier strip of axial components. 
           [0019]      FIG. 8  is an illustration of an embodiment including a hand-held device. 
       
    
    
       [0020]    Like reference symbols in the various drawings indicate like elements. 
       DETAILED DESCRIPTION 
       [0021]    component placement machines may be supplied by various types of component feeders configured for particular types of packaging.  FIG. 1  illustrates one type of packaging known as a component reel.  FIG. 2A  illustrates an alternative form of component packaging  20  sometimes referred to as an ammunition pack or a fan-fold box. As illustrated, a component strip  22  is folded in a fan-like manner and packaged in a box  20  instead of a reel. The ammunition box  20  includes two opposite lids  74 A,  24 B, each providing access to one of the two ends  26 A,  26 B of the component strip  22 . As illustrated in  FIGS. 2B and 2C , the component orientation with respect to strip edge  26 A differs from the component orientation with respect to strip edge  26 B. 
         [0022]    In some instances, it may be advantageous to maintain a constant supply of components to the component placement machine by reloading the machine before the current supply is exhausted. In cases where a component carrier strip is used, a machine can be relaoded by splicing a second component carrier strip onto the loaded component strip. 
         [0023]      FIGS. 3A and 3B  illustrate a component carrier strip  30  connected to a second component carrier strip  32  by a splice connection  34  disposed there between. As illustrated in  FIG. 3B , the orientation of the components on the component strip  30  differs from the orientation of the components on the component strip  36 . If left undetected, subsequent placement of the components on the printed circuit board may result in improper operation for certain types of components, e.g., electrolytic capacitors and transistors. Early detection of any inconsistencies may result in improved efficiency and fewer reworks. 
         [0024]      FIG. 4A  is an illustration of an embodiment including a blind slot  42  and four press-button switches  44 . Each switch is positioned on a visible surface  46  at a location corresponding to an expected orientation of a component marking with respect to the blind slot  42 . As illustrated, the blind slot is mounted on the surface  46  of the housing  48  and defines an opening  40  for receiving the leading edge of a component strip. Alternate embodiments may include other arrangements for indicating the appropriate positioning of the component strip, e.g., a slot defined by the housing, appropriately spaced pegs on the surface of the housing, or an illustration  47  attached to the surface  46  depicting the proper positioning of the component strip as illustrated in  FIG. 4B . 
         [0025]    Some embodiments may include less than four switches or more than four switches depending on the varying locations of the orientation mark. For example, configurations used strictly for identifying the orientation of electrolytic capacitors may include at most two switches positioned along an axis parallel to the opening defined by the slot. Configurations used strictly for identify the orientation of integrated circuit chips may have four switches  44 ′, each positioned at one of four corners about the perimeter of the component strip placement area  49  as shown in  FIG. 4B . Other configurations used for identifying the orientation of varying component types may have six or more switches appropriately positioned about the component strip placement area. 
         [0026]      FIGS. 5A and 5B  are side and top views, respectively, illustrating the insertion of a leading edge of a component strip  52  into a blind slot  54 . As illustrated, the component strip  50  is inserted vertically into the blind slot  54  such that the components  56 , e.g. capacitors, and the respective orientation markings  57  remain visible to the operator. As discussed above, the slot may also be defined by the housing  58 . Alternative implementations also include positioning the leading edge  52  of the component strip  50  horizontally on the surface  46  as depicted in  FIG. 4B . 
         [0027]      FIG. 6  is a flow-chart for loading a component carrier strip. As illustrated, the operator enters the part number of the component to be inserted  61 . The operator then inserts a free end of the carrier strip into the blind slot  62  and presses the corresponding button to indicate the orientation of the polarity mark  63 . The operator then enters the slot number identifying the location on the component machine to be loaded  64 . If the orientation indicated matches the expected or preprogrammed orientation  65 A, no error occurs and the operator proceeds to load the component strip onto the component placement machine  68 , e.g., by splicing the free end of the component strip to the tail end of a previously loaded component strip. If, however, the orientation indicated does not match the expected orientation  65 B, an error occurs and steps are initiated to prevent the incorrect loading of the component strip onto the component placement machine. In one embodiment, the component placement machine is halted by asserting a cycle stop signal on a communication bus of the component placement machine. Subsequently, the operator corrects the error by loading the opposite end of the component strip  66 . In certain embodiments, additional steps may be required to continue processing such as clearing an error flag or a stop signal  67 . 
         [0028]    In some instances, components may be aligned on a component strip such that it is difficult to differentiate one face of the component strip from the opposite face. This is typically the case for axial components such as resistors and diodes. In these instances, an operator may inadvertently flip the component strip prior to loading it onto the component placement machine, thereby reversing the component orientation with respect to the leading edge of the component strip. 
         [0029]      FIG. 7  is a flow chart for loading a component carrier strip of axial components. As illustrated, the operator enters the part number corresponding to the component reel  71  and then loads the component strip onto the component placement machine  72 , e.g., by splicing the free end of the component strip to the tail end of a previously loaded component strip. The operator then enters the slot number corresponding to the location on the component placement machine to be loaded  73 . Alternatively, the slot number may be identified automatically through the use of a sensor on the feeder slot. The operator is then prompted to input the orientation of the component strip with respect to a fixed point of reference  74 . For example, software is executed on the component placement machine controller requesting keyboard input from the operator indicating the component orientation is on the outside or the inside of the component placement machine. Other points of reference may be used to indicate the orientation of the component, such as the input device, the feeding direction, or the component placement machine controller. Alternatively, the software may be executed on a stand-alone computer apart from the component placement machine controller, e.g., a PDA, laptop, or desktop workstation. In addition, other types of input devices may be used to indicate the component orientation, e.g., a touch-screen, a stylus, or a hand held remote barcode scanner. If the orientation indicated matches the expected or preprogrammed orientation  75 A,  110  error occurs. If, however, the orientation indicated does not match the expected orientation  75 B, an error occurs and steps are initiated to correct the orientation of the components. In one embodiment, the component placement machine is halted by asserting a cycle stop signal on a communication bus of the component placement machine. Subsequently, the operator corrects the error by reversing the orientation of the components  76 . In certain embodiments, additional steps may be required to continue processing such as clearing an error flag or a stop signal  77 . 
         [0030]      FIG. 8  illustrates an embodiment including a hand-held device  80  for indicating the component orientation after the component strip  82  has been loaded onto a component placement machine. The hand-held device includes a graphical display  86  indicating the proper orientation of the hand-held device  80  to the component strip  82 , e.g., by indicating that the leading edge  83  of the component strip  82  is to be aligned with the top of the display  85  and the remaining portion of the component strip is to be aligned with the bottom of the display  87 . The hand-held device also includes two push-buttons  88  for indicating the orientation of the component marking  89 . Alternatively, the hand-held device  80  may include a touch screen capable of graphically displaying the push-buttons and accepting input from the operator. In another embodiment, the hand-held device may include a label indicating the proper orientation of the hand-held device with respect to the component strip. 
         [0031]    A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, the blind slot may be one of several adapters used to accommodate component strips of different dimensions, to reposition component strips for different component types, and/or to accommodate different types of component packaging. In addition, the component placement machine may be configured to compensate for the detected component orientation by adjusting the component placement accordingly. Thus, other embodiments are within the scope of the following claims.