RELATED APPLICATION  
       [0001]     The present application is a continuation-in-part of U.S. patent application Ser. No. 11/147,647, filed Jun. 8, 2005, which is based on and claims priority to U.S. Provisional application Ser. No. 60/578,481, filed Jun. 9, 2004. 
     
    
     BACKGROUND  
       [0002]     1. Field of Invention  
         [0003]     The present invention relates generally to printer systems, and more particularly to managing multiple printers within a printer system.  
         [0004]     2. Related Art  
         [0005]     A main function of printer systems is to deliver printed images. One example of printed images is bar code labels that are used in the supply chain for efficient processing and handling of goods in transit. Typically, a roll of media, such as labels, is inserted into a printer, and the labels are passed through a printing mechanism, such as a thermal print head. As each label passes, the printing mechanism prints an appropriate image, such as a bar code. The printed label can then be applied to a package if desired.  
         [0006]     As label technology advances and needs increase, it becomes increasingly difficult for a single printer to process the media efficiently and correctly. For example, colors are now required for many labels. However, color printing using a single printer can be costly, difficult, and/or inefficient. Increasing throughput is always desirable, and as labels are becoming ever more complex, high throughput is becoming more difficult. Recent developments in technology now also allow Radio Frequency Identification (RFID) inlays (passive or active transponders) to be embedded in a bar code label. The transponder provides an electronic means of storing information and a non-contact, non-line of sight method for reading the stored data.  
         [0007]     One common method for encoding RFID bar code labels is to use a printer/encoder. In such a system, an RFID encoder (sometimes called a reader) and antenna is integrated in the printer to enable both printing of the label information and programming of the RFID tag. RFID labels, such as for cartons or pallets, can be produced by embedding the RFID tag in a label, programming information into the tag, such as from a host computer, and based on the information, printing the label with a proper bar code and/or other printable information using the printer. RFID labels can also be produced in a printer by first printing on the label and then programming or encoding the RFID tag in the label. These labels can then be read by both a bar code scanner and an RFID reader.  
         [0008]     However, many single printers are not capable of printing and encoding. Ones that are may not be overly efficient. Thus, there is a need for a printer system that is able to more efficiently handle today&#39;s printing requirements.  
       SUMMARY  
       [0009]     According to one aspect of the present invention, a printer system includes a general purpose input/output (GPIO) system that can be driven by any internal printing, encoding or verification event or by external events. Through a unique mapping capability the GPIO system can, through a series of logical functions, generate output events (“actions”) to drive external devices or to control printer internal activities. Mapping of events to actions is done through an IO System Manager.  
         [0010]     The GPIO system enables multiple printers to be coordinated so that a printer system comprising the GPIO system and multiple printers can be used to perform printing functions more efficiently. The GPIO system also enables functions with a single printer to be managed more effectively through the mapping to output events.  
         [0011]     As a result of the programming flexibility of the GPIO system, it allows, among many other applications, full control of a label print-and-apply system by the printer. It does not necessarily require additional control devices, as the printer with its resident GPIO system can function as the device controlling the complete application.  
         [0012]     Applications that do not need a direct interface to the outside can still benefit from the GPIO system. For example, a printer status reporting based on internal printer events can be done through the standard printer interfaces without additional hardware installed.  
         [0013]     In one embodiment, the GPIO system manages two or more printers with a printer system. For example, two printers can be connected through the GPIO. One is designated as the system master, and the other one is designated as the slave. Both printers receive the same data, but the GPIO only instructs the master to print. If the master is able to successfully print, the slave discards the received data and the master continues printing. However, if the master is unable to print successfully, the GPIO system will instruct the slave to print, such as initiating an exchange of master/slave designations between the printers. The slave then continues the printing while the problem with the master is being fixed. The slave continues printing even after the master is fixed. When the slave is unable to print, the GPIO system then instructs the master to begin printing, while the slave is fixed. This enables continued uninterrupted printing, while still enabling approximate equal usage of both printers over time. Consequently, printing can continue for a longer period of time before one of the printer permanently fails and needs to be replaced.  
         [0014]     In another embodiment, the printers receive the same data, but only one of the printers will print, based on the data stream. For example, one printer can be an RFID printer that enables encoding and reading of RFID tags and printing of labels, while the other printer can be just a bar code printer. So, if the data stream contains an RFID command, the RFID enabled printer will print, while the bar code printer will discard the data. This enables a printer system to handle multiple types of printing without user intervention.  
         [0015]     Another embodiment allows printers to print labels in sequence and in synchronization with packages or boxes passing by the printers on a conveyor belt system. The printers are interconnected through the GPIO system so that if one printer develops a problem, the conveyor belt can be slowed down so that printing can continue successfully using the remaining printers. When the problem is resolved, the speed is increased back to normal. This enables a labeling system to operate more quickly and efficiently.  
         [0016]     In yet another embodiment, the GPIO system interconnects printers supporting different color printing, such as one printer for black and another for red. Each printer prints only the color of the loaded ribbon. After one color is printed, the label is moved to the next printer for printing another color. The GPIO system synchronizes the printing so that variations in speed to not adversely affect the overall printing. This enables multi-color labels to be printed quickly and at a lower cost.  
         [0017]     This invention will be more fully understood in light of the following detailed description taken together with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]      FIG. 1  is a block diagram of a GPIO system according to one embodiment of the present invention;  
         [0019]      FIG. 2  is a block diagram of a GPIO hardware portion of the GPIO system of  FIG. 1 , according to one embodiment; and  
         [0020]     FIGS.  3  to  6  are flow charts illustrating applications of the GPIO system according to different embodiments. 
     
    
       [0021]     Embodiments of the present invention and their advantages are best understood by referring to the detailed description that follows. It should be appreciated that like reference numerals are used to identify like elements illustrated in one or more of the figures.  
       DETAILED DESCRIPTION  
       [0022]      FIG. 1  is a block diagram of a general purpose input/output (GPIO) system  100  according to one embodiment, contained within a printer  102 . Printer  102  can be any suitable printer, such as a thermal, laser, or impact printer. GPIO system  100  includes a GPIO hardware portion  104  and a GPIO software portion  106 . GPIO software portion  106  communicates with a printer controller  108 . The printer controller controls functions of a printer. So, in response to signals from GPIO software portion  106 , printer controller  108  can send appropriate command instructions to the printer. GPIO hardware portion  104  can be an IO board mounted in the printer, and GPIO software portion  106  can be a PC-based GPIO manager that allows the user to define how the general purpose IO hardware should behave for a given application and a printer resident GPIO event parser.  
         [0023]     GPIO hardware portion  104 , e.g., a GPIO board, handles the actual interfacing of the printer to the outside world, i.e., external signals, components, and devices. Examples include interfaces to external devices such as sensors, conveyor systems, label applicators, pneumatic devices, etc. The interface includes an input section  110  comprising of eight optically isolated inputs and an output section  112  comprising of eight optically isolated outputs and four SPDT relay contacts. GPIO hardware portion  104  also includes power, such as a 24V DC and a 5V DC supply, for providing power to external devices.  
         [0024]      FIG. 2  is a more detailed block diagram of GPIO hardware portion  104  having eight optically coupled outputs  200 , four relay outputs  202 , and eight optically coupled inputs  204 . The opto-couplers, in one embodiment, comprise a GaAs LED and an NPN Silicon phototransistor, such as the NEC PS2501-4 opto-coupler. The relays, in one embodiment, are NAiS TX type relays. For simplicity, not all outputs and inputs are shown. The outputs  200  and  202  and inputs  204  are coupled to an IO system control logic  206 . Logic  206  enables outputs  200  and inputs  206  to be connected to the printer system. Detailed description of the circuits, inputs, outputs, and relays can be found in Appendix B.  
         [0025]     Referring back to  FIG. 1 , GPIO system  100  also includes GPIO software portion  106 . GPIO software portion  106  includes an event parser  114 , a mapping table  116 , and an action portion  118 . Also included is a software initiation section which sets up the hardware (hardware detection and initialization), sets up the mapping tables (internal and user-defined), and creates front panel menus. Event parser  114  parses events or events specified in the mapping table. For example, when event parser  114  receives an event, it will search the mapping table for action(s) associated with the event. Multiple actions can be linked to one event. If one or more actions are found, event parser  114  will execute them. The events can originate from various sources. These include the GPIO input section (inputs  204 ), events happening anywhere in the printer, and polling for certain conditions.  
         [0026]     Mapping table  116  contains a list of so-called “Event to Action Mappings”. There is one internal preset mapping table stored in the printer and one “user-defined” table can be downloaded to a flash file-system. Each mapping consists of the following parts: 1) a mapping name to describe the event to action mapping, 2) an event name to describe the event and an event ID to uniquely identify the event, and 3) an action name to describe the action, an action ID to uniquely identify the action, and action parameters for performing the action.  
         [0027]     Action portion  118  communicates the desired or selected action to GPIO hardware portion  104  (through output section  112 ) and printer controller  108 . Additional details on GPIO software portion  106  can be found in Appendices A and B.  
         [0028]     Thus, event parser  112  uses events and actions to allow GPIO system  100  to behave as required. Events can either be printer internal, such as “paper out” or “print complete”, or printer external, such as “opto-coupler 1 active”. Actions are the result of (or the reaction to) an event and can also be printer internal like “paper feed” or printer external like “relay 1 active” or a “reply to host”, where data is transmitted over either the serial, parallel, or network interface. A number of events can also be acted upon without the GPIO card being installed in the printer and enables the printer to be adapted for the application it is used in. Table 1 below lists available events according to one embodiment.  
                   TABLE 1                       Events   Parameters                   Input Opto-Coupler   Opto-Coupler Number (1 . . . 8), Active,           Inactive       Printer Powered Up   n.a       Printer Online   n.a       Printer Offline   n.a       Printer Local   n.a       Power Save Mode Active   n.a       Power Save Mode Cleared       Start Data Processing   n.a       End Data Processing   n.a       Printer Buffers Empty   n.a       Label Pending   n.a       Start Printing   n.a       Start Paper Move (1)     n.a       Label Printed   n.a       Label Present   n.a       Label Taken   n.a       Job Printed   n.a.       End Paper Move (1)     n.a       Printer Error   Any, Paper Out, Paper Jam, Ribbon Out,           TOF Detect Fault, Print Head Open,           RFD Tag failed, RFID max. retry       Printer Warning   Any, Ribbon Low       Panel Key Event   Key name       ODV Events   Missing barcode,           Quality error - Any or a specific one,           All ODV errors cleared       Data Field Changed   Field Id, Condition, Type                  
 
         [0029]     An event is the moment in time when a listed signal changes state, e.g., the event “Printer On-Line” happens at the moment the printer is switching from the “Printer Off-Line” state into the “Printer On-Line” state.  
         [0030]     A number of events have parameters attached to them, e.g., to more specifically define the event to which the related action should be mapped. For example, the “Printer Error” event can have one of two forms, the first more generalized form in which the event happens on any printer error (“any” selected as parameter) or the more specific form in which, e.g., “paper out” is specified as the condition for this event (“paper out” selected as parameter).  
         [0031]     Events can be mapped to actions. An action is that what should happen when the event occurs and can be either internal or external. With the exception of the Input events and Output actions, all events and actions can be used without the hardware installed. This allows, e.g., the Status Reporting capability of the General Purpose IO System to be used. Possible actions are listed in Table 2 below according to one embodiment.  
                   TABLE 2                       Actions   Parameters                   Output Opto-Coupler   Opto-Coupler Number (1 . . . 8), Activate,           Deactivate, Pulse       Output Relay   Relay Number (1 . . . 4), Activate,           Deactivate, Pulse       Printer Online   n.a       Printer Offline   n.a       On/Offline switch   n.a       Clear Buffer   n.a       Pause Printing   n.a       Start Printing   n.a       Print Next Label   n.a       Reprint Last Printed Label   n.a       Form Feed   n.a       Move Paper   TOF, Specified Distance Forward/Backward       Cut Once   n.a.       Delete Page   n.a.       Lock Operator Panel   n.a       Unlock Operator Panel   n.a       Key Events   n.a       Enable GPIO Events   n.a       Disable GPIO Events   n.a       Reply to Host   Data to be Transmitted, Interface to be used       Wait   Data Field, time in mS x50       PAA control, Reset CST   n.a.       Select Mapping Table   Mapping Table ID       Data Field   Name, Operator, Type       Send Report   Name, Operator, Type                  
 
         [0032]     An action is that what happens as a result of an event. For example, if the event “On-Line” is mapped to the action “Print Next Label”, the printer will print a label as soon as it is switched to the On-Line state (and if a label is present in the buffer). Or, if a panel key event is mapped to the action “Cut Once”, the panel key used now has a new function, the cutting of labels.  
         [0033]     A number of actions have parameters attached to them, which can be used to more specifically define the action that should be executed. For example, the parameters related to the action “Move Paper” allow the movement to top of form (TOF) (either forward or reverse) or allow a specified distance to be moved forward or reverse.  
         [0034]     Several actions can be mapped to a single event. A key event could be mapped such that it cuts the label just printed and also initiates the printing of the next label. Events can be mapped to actions. An action is that what should happen when the event occurs and can be either internal or external.  
         [0035]     GPIO system  100  also includes a PC/Workstation based GPIO Manager. In one embodiment, this is the actual Windows or Unix based Graphical User Interface that allows the user to program the GPIO mapping tables. Each entry in the table has a description, an event and an action listed. The way in which this is designed makes the tables self-documenting.  
         [0036]     Thus, GPIO system  100 , through a mapping capability, can generate output events through a series of logical functions to drive any external device.  
         [0037]      FIGS. 3-6  are flow charts showing various embodiments for GPIO system  100  to generate different output events for improving printer performance.  FIG. 3  illustrates a process for uninterrupted printing. In operation  300 , two equivalent printers are interconnected through the GPIO system in a Master/Slave configuration. The same data is transmitted to both printers in operation  302 . If the printer designated as the Master is unable to print, such as due to a damaged component, as determined in operation  304 , the GPIO system will autonomously initiate an exchange of roles between the two printers such that the Slave printer will become Master in operation  306 . The new Master then continues printing in operation  308 . When the initial Master printer is able to print again, the initial Master is designated the Slave printer by the GPIO system. If the new Master develops a problem and cannot print, the new Slave is designated the Master and continues the print job in operation  310 .  
         [0038]     In this manner, the two printers alternate when one is unable to print, with printing stopped by one printer only when that printer is unable to print. As a result, printing is uninterrupted, and the usage for both printers is approximately the same over time. This allows the printing system of the two printers to be used for an extended amount of time before one of the two printers needs to be replaced. For example, if one printer ends up printing 80% or 90% of the time, obviously that printer will need to be replaced much sooner than if it were only used approximately 50% of the time.  
         [0039]     The GPIO system also allows a problem status to be reported to a host computer system through any of the standard interfaces as well as to the operator either through a set of warning lights, sounds, through the printer resident LCD, or through a combination. If this application includes a print and apply system, the GPIO system can be used to control the applicator such that it will “know” which of the two printers has a valid label to apply.  
         [0040]      FIG. 4  shows a process for color printing. In operation  400 , multiple printers, each with a different color ribbon, are interconnected through the GPIO system. Media, such as a roll of labels, is fed from one printer to the next in operation  402 . Each printer receives and prints, in operation  404 , that part of the data that should be printed in the color of the loaded ribbon. The GPIO system then determines, in operation  406 , whether the print speeds of the printers are the same. If not, the GPIO system synchronizes the printers in operation  408  to compensate for the differences, resulting in a uniform and high quality image. If the printers are all at the same print speed, printing continues in operation  410 . All additional capabilities of the GPIO system, such as applicator control and status reporting will be available.  
         [0041]      FIG. 5  illustrates a process for handling different types of print data. In operation  500 , multiple printers each with different capabilities and different media are interconnected through the GPIO system. For example, one of the printers can be an RFID-enabled printer capable of reading and encoding RFID tags and labels. The RFID-enabled printer can also print bar code labels. The other printer can be a printer capable of printing only bar codes. Other types and numbers of printers can also be interconnected. Each printer in the system receives the same data in operation  502 . The GPIO system, in operation  504 , determines the data type from the data stream, such as by detecting an RFID command or other indicator. The GPIO system then commands only the printer capable of handling the data stream to operate on the data, such as RFID encoding. Thus, only one of the printers should, depending on the data stream content, print the job at hand in operation  506 . The GPIO system, in combination with an application adapter, can be programmed such that only the printer that can handle the data received will print it. All additional capabilities of the GPIO system, such as applicator control and status reporting, will be available.  
         [0042]      FIG. 6  illustrates a process for handling multiple printers in a conveyor belt print and apply system. In operation  600 , multiple printers are interconnected through the GPIO system along a high speed conveyer belt. Optical sensors report, in operation  602 , items to be labeled to the GPIO system, which in turn will make sure the labels are printed in the correct sequence. The labels are then printed in operation  604 . If one of the printers in the system develops a problem, as determined in operation  606 , the GPIO system lowers the speed of the conveyer belt and alarms the operator in operation  608 . Printing continues at this slower speed, in operation  610 , to prevent interruption or faulty printing. Following the resolution of the problem, the GPIO system will speed up the conveyer belt, and normal printing continues. If all printers are operating properly, normal printing conditions continue in operation  612 . Additional capabilities of the GPIO system, such as status reporting, will be available.  
         [0043]     Having thus described embodiments of the present invention, persons skilled in the art will recognize that changes may be made in form and detail without departing from the scope of the invention. Thus the invention is limited only by the following claims.
A printer system includes a general purpose input/output (GPIO) system that can be driven by any internal printing, encoding or verification event or by external events. Through a unique mapping capability the GPIO system can, through a series of logical functions, generate output events ("actions") to drive external devices or to control printer internal activities. In one embodiment, the GPIO alternates Master and Slave designations of two printers in the system, so that when one printer is unable to print, the other printer is used to print and continues printing until it can no longer print. At that time, the other printer is used. This alternation continues for equal use between the two printers.