Patent Publication Number: US-9849708-B1

Title: Microwave dryer of a print system with modulation of the microwave source using frequency shift keying

Description:
FIELD OF THE INVENTION 
     The invention relates to the field of printing systems, and in particular, to microwave dryers of printing systems. 
     BACKGROUND 
     Production printing systems for high-volume printing typically utilize a production printer that marks a continuous-form print medium (e.g., a web of paper) with a wet colorant (e.g., an aqueous ink). After marking the print medium, a dryer downstream from the production printer is used to dry the colorant. One such dryer is a microwave dryer that uses microwave energy to heat the colorant to cause a liquid portion of the colorant to evaporate, thereby fixing the colorant to the print medium. The primary mechanism of heating the colorant is dielectric heating. 
     In a typical microwave dryer, a microwave source directs the microwave energy down a long axis of a waveguide which spans across the width of the print medium. The print medium travels through a short axis of the waveguide via a passageway through the waveguide. As the continuous-form print medium traverses the short axis of the waveguide, the wet colorants applied to the continuous-form print medium are exposed to the microwave energy and dried. 
     One problem with such microwave dryers is that the microwaves emitted by the microwave source are standing waves inside the cavity of the waveguide. That is, the electromagnetic field along the long axis of the waveguide oscillates in intensity with high power density at peaks of the wave and low power density between the peaks of the wave. Variation of the field intensity across the width of the web leads to heating variations across the width of the web and non-uniform drying of the print media. 
     SUMMARY 
     Embodiments herein describe a microwave dryer of a print system with modulation of the microwave source with using frequency shift keying (FSK). A microwave dryer is enhanced to control an output of an FSK modulator to a microwave source. The output of the FSK modulator modifies the fixed frequency value of the microwave source (e.g., 2.45 GHz) such that the microwave source instead oscillates above and below its normally fixed frequency. Changes to the operating frequency of the microwave source results in a more uniform distribution of intensity/heat across the width of a print media traveling through the microwave dryer. Implementation of FSK, which is a digital form of frequency modulation, enables the microwave dryer to adapt to a large range of drying requirements. 
     One embodiment is a microwave dryer that includes a waveguide configured to transport electromagnetic energy to dry a wet colorant applied to a continuous-form print media by a printer. The waveguide includes a structure with a long axis that extends across a width of the print media, and includes a passageway through the structure to pass the print media through a short axis of the waveguide. The passageway is sized to pass the continuous-form print media through the structure. The microwave dryer also includes a microwave source coupled to the waveguide configured to provide the electromagnetic energy at an operating frequency, and a frequency shift keying (FSK) modulator coupled to the microwave source configured to modulate the operating frequency with a series of discrete frequencies to vary intensity positions to reduce a variation of intensity of the electromagnetic energy in a direction across the width of the print media. The microwave dryer further includes a processor coupled to the FSK modulator configured to determine a period of time for the print media to traverse through the short axis of the waveguide, to determine a modulating signal with a modulating frequency based on the period of time, to determine a number of frequencies that approximate the modulating signal at the modulating frequency, and to apply binary values that represent the number of frequencies to an input of the FSK modulator to cause the FSK modulator to output the series of discrete frequencies over the period of time. 
     Another embodiment is a method that includes operating a microwave source coupled to a waveguide by generating electromagnetic energy at an operating frequency with the microwave source and transporting the electromagnetic energy with the waveguide to dry a wet colorant applied to a continuous-form print media by a printer. The waveguide includes a structure with a long axis that extends across a width of the print media, and includes a passageway through the structure to pass the print media through a short axis of the waveguide. The passageway is sized to pass the continuous-form print media through the structure. The method also includes determining, with a processor, a period of time for the print media to traverse through the short axis of the waveguide, determining a modulating signal with a modulating frequency based on the period of time, and determining a number of frequencies that approximate the modulating signal at the modulating frequency. The method further includes applying binary values that represent the number of frequencies to an input of a frequency shift keying (FSK) modulator to modulate the operating frequency with a series of discrete frequencies that vary intensity positions to reduce a variation of intensity of the electromagnetic energy in a direction across the width of the print media over the period of time. 
     Other exemplary embodiments (e.g., methods and computer-readable media relating to the foregoing embodiments) may be described below. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       Some embodiments of the present invention are now described, by way of example only, and with reference to the accompanying drawings. The same reference number represents the same element or the same type of element on all drawings. 
         FIG. 1  is a block diagram of a printing system in an exemplary embodiment. 
         FIG. 2  is a perspective view of a microwave dryer. 
         FIG. 3  illustrates a top view of a microwave dryer of a print system with modulation of the microwave source using frequency shift keying (FSK). 
         FIG. 4  is a flow chart of a method of operating a microwave dryer in an exemplary embodiment. 
         FIG. 5  is a flow chart of a method of modulating a microwave energy source of a microwave dryer with a series of discrete frequencies in an exemplary embodiment. 
         FIG. 6  illustrates a plot of a modulating signal in an exemplary embodiment. 
         FIG. 7  illustrates an intensity plot and a field strength plot according to an FSK modulation of microwave source using eleven discrete frequencies in an exemplary embodiment. 
         FIG. 8  illustrates a plot of a modulating signal approximated with three unique frequencies in an exemplary embodiment. 
         FIG. 9  illustrates an intensity plot and a field strength plot according to an FSK modulation of microwave source using three discrete frequencies in an exemplary embodiment. 
         FIG. 10  illustrates a processing system operable to execute a computer readable medium embodying programmed instructions to perform desired functions in an exemplary embodiment. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     The figures and the following description illustrate specific exemplary embodiments of the invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the invention and are included within the scope of the invention. Furthermore, any examples described herein are intended to aid in understanding the principles of the invention, and are to be construed as being without limitation to such specifically recited examples and conditions. As a result, the invention is not limited to the specific embodiments or examples described below, but by the claims and their equivalents. 
       FIG. 1  is a block diagram of a printing system  100  in an exemplary embodiment. Printing system  100  generally includes a printer  102  and a microwave dryer  108 . Printer  102  applies a wet liquid or colorant (e.g., aqueous inks, oil-based paints, etc.) to a top surface  116  of print media  112  (e.g., a continuous-form print medium such as paper). In doing so, a print controller  104  of printer  102  receives print data  110  for imprinting onto print media  112 , which is rasterized by print controller  104  into bitmap data. The bitmap data is used by a print engine  106  (e.g., a drop-on-demand print engine, a continuous-ejection print engine, etc.) to apply wet colorant to print media  112 . After being marked with wet colorant, print media  112  travels in the direction indicated by the arrow along a media path  118  in  FIG. 1 . Microwave dryer  108  applies electromagnetic energy  114  (e.g., microwave energy) to print media  112  which heats the wet colorants applied to print media  112  to evaporate a liquid portion of the wet colorants, thereby fixing the wet colorants to print media  112 . Printer  102 , print controller  104 , print engine  106  and microwave dryer  108  may be separate devices or incorporated with one another in various embodiments. 
       FIG. 2  illustrates a perspective view of a microwave dryer  200 . Microwave dryer  200  includes a microwave source  202 , such as a magnetron, that generates microwaves, and a plurality of microwave waveguides  204 - 207 . Microwave waveguides  204 - 207  are electromagnetically coupled together in a pattern such that microwave energy injected by microwave source  202  into one end of a waveguide  204  follows a serpentine path (e.g., an “S” pattern) from one end to another end of each of the microwave waveguides  204 - 207 . Coupling of waveguides  204 - 207  may include electromagnetic bend couplers (e.g. e-bend coupler) with other shapes and dimensions from that shown in the figures which illustrate right angle turn coupling for ease of illustration. Microwaves generated by microwave source  202  travel from left to right in waveguide  204  in  FIG. 2 , are re-directed to waveguide  205  via the bend coupler, and then travel from right to left in waveguide  205 . This back and forth pattern continues for waveguides  206 - 207 , with the microwaves taking a serpentine path through microwave waveguides  204 - 207 . 
     Microwave waveguides  204 - 207  each have a long axis that spans across a width of the print media  112  and a passageway  210  (not labeled for waveguide  204  for illustration purposes) that is a path for the print media  112  through a short axis through the microwave waveguides  204 - 207  that is sized to accept print media  112 . The passageway  210  may have a width that is at least as wide as print medium  112  and width less than the length of microwave waveguide  204 - 207 . The microwave waveguide short axis is generally in the direction of the media path  118  (e.g., parallel or substantially parallel to travelling direction of print media  112  and orthogonal to the long axis). Microwave waveguides  204 - 207  are spaced from one another with successive microwave waveguides  204 - 207  placed downstream in parallel fashion in the print media  112  direction along media path  118 . Since waveguides  204 - 207  may be hollow, passageway  210  may include two openings at either end of the short axis along the media path  118  in each waveguide  204 - 207  for passage of print media  112  through each waveguide  204 - 207  (the vertical height of the openings being shorter than the vertical height of the hollow portion of each waveguide  204 - 207 ). For embodiments in which adjacent waveguides  204 - 207  abut one another, adjacent openings of different passageways  210  may have a common boundary that defines the area for passing print media  112  through adjacent waveguides  204 - 207 . At the last coupled microwave waveguide of  204 - 207  of microwave dryer  200 , a termination element (not shown) (e.g. shorting plate or matched load) is located at the un-coupled end to terminate the microwaves. Termination element produces standing waves in the microwave waveguides  204 - 207  if it is a shorting plate and produces traveling waves in microwave waveguides  204 - 207  if it is a matched load. 
     In  FIG. 2 , the microwaves are illustrated within waveguide  204  as a standing wave that forms Radio Frequency (RF) peaks with a high concentration of energy that creates high energy areas  220  across the exposed width of the print media  112 . In between the high energy areas  220 , lower concentrations of RF energy create low energy areas  222  across the width of the print media  112 . Wet colorants on print media  112  dry faster when exposed to high energy areas  220  versus low energy areas  222 . The result is a series of electromagnetic high energy and low energy spots that vary in position across the exposed width of print media  112  that reduce drying quality and the printed output of printing system  100 . The high energy areas  220  and low energy areas  222  shown in waveguide  204  extend through the coupled waveguides  204 - 207  in a similar manner though they are not shown. In other embodiments, the microwaves in the coupled waveguides  204 - 207  are traveling waves that produce high energy areas  220  and low energy areas  222  within the waveguides  204 - 207 . Microwave dryer  200  may therefore be enhanced to minimize the high energy and low energy region variation across the width of print media  112  for even heating and drying across print media  112 . 
       FIG. 3  illustrates a top view of microwave dryer  300  of a print system (e.g., printing system  100 ) with modulation of the microwave source using frequency shift keying (FSK) in an exemplary embodiment. Microwave dryer  300  includes a frequency shift keying (FSK) modulator  320  and a processor  330  that operate in conjunction with microwave source  302  to provide uniform heating across the width  310  of print media  112 . Microwave source  302  (e.g., a magnetron) has an input coupling to control the frequency modulation of the operating frequency (e.g., 2.45 GHz, 915 MHz, or another operating frequency). By frequency modulating the operating frequency of microwave source  302 , microwave dryer  300  continually repositions the RF peaks along the width  310  of print media  112  to evenly distribute heating and eliminate the pattern of electromagnetic high energy areas  220  and low energy areas  212  described in  FIG. 2 . 
     FSK modulator  320  is any system, device, or component operable to couple to microwave source  302  and to modulate the operating frequency of microwave source  302 . Processor  330  is any system, device, or component operable to control FSK modulator  320  with a binary input. Suppose, for example, that microwave source  302  operates with an operating frequency of 2.45 GHz to inject microwaves at one end of waveguide  204 . The microwaves traverse along a long axis of waveguide  204  across the width  310  of the print media  112  to another end of waveguide  204 . Print media  112  traverses crosswise through waveguide  204  via passageway  210  to expose print media  112  for a width  312  of waveguide  204  along media path  118  (e.g., across the short axis of waveguide  204 ). Accordingly, waveguide  204  may include a passageway  210  (not shown in  FIG. 3 ) having a width slightly larger than the width  310  of print media  112  or media path  118 . With FSK modulator  320  and/or processor  330  coupled to microwave source  302 , FSK modulator  320  may be applied to microwave source  302  to cause a shift in the operating frequency, thereby distributing the intensity of the electromagnetic energy  114  across the width  310  of print media  112 . 
     In general, microwave dryer  300  implements a form of frequency modulation known as frequency shift keying (FSK). In frequency modulation, a carrier signal is changed by a modulating signal. More particularly, the amplitude of the modulating signal defines how far (in frequency) the carrier signal shifts, and the frequency of the modulating signal determines how quickly the carrier signal shifts from one frequency to another. Unlike analog frequency modulation which requires an infinite number of frequency states, FSK is a digital modulation protocol that changes the frequency of a carrier signal using a discrete number of frequencies and is typically used in communication systems to transmit digital data over an analog signal. One advantage of FSK over analog frequency modulation is that modulation may be achieved with digital components. As described in greater detail below, FSK as implemented by FSK modulator  320  and processor  330  enables microwave dryer  300  to quickly adapt to variables in a print system such as printing system  100 . 
     FSK modulator  320  and/or processor  330  may be implemented as custom, circuitry, one or more Central Processing Unit(s) (CPU), microprocessor(s), Digital Signal Processor(s) (DSP), Application-specific Integrated Circuit(s) (ASIC), etc. Although  FIG. 3  shows two coupled microwave waveguides  204 - 205 , any number of coupled microwave waveguides may be utilized as a matter of design choice to achieve a desired level of performance for drying wet colorants applied to print media  112  by printer  102 . Furthermore, electromagnetic energy  114  generated by microwave source  302  may travel from the end of one microwave waveguide to the beginning of another waveguide via bend coupler  315  (e.g. E-bend coupler) shown in  FIG. 3 . The last waveguide in a row of waveguides may include a termination element  317  (e.g. shorting plate or matched load) located at the uncoupled end to terminate microwaves. Microwave waveguides  204 - 205 , bend coupler and termination element  317  designs are chosen based on the operating frequencies. 
       FIG. 4  is a flow chart of a method  400  of operating microwave dryer  300  in an exemplary embodiment. Though discussed with respect to printing system  100  of  FIG. 1  and microwave dryer  300  of  FIG. 3 , method  400  may apply to other systems. The steps of method  400  are not inclusive, may include additional or alternative steps, and may be performed in an alternate order. 
     In step  402 , microwave source  302  generates electromagnetic energy  114  at an operating frequency (e.g., 2.45 GHz). As earlier described, microwave source  302  may be coupled with waveguide  204  to provide electromagnetic energy  114  to a substantially confined channel defined by the walls of waveguide  204 . In step  404 , waveguide  204  transports the electromagnetic energy  114  to dry a wet colorant applied to a continuous-form print media  112  by a printer (e.g., printer  102 ). In that regard, waveguide  204  may include a structure with a long axis that extends across a width of the print media, and may further include a passageway in the structure to allow passage of print media  112  traveling along a media path in microwave dryer  300 . 
     In step  406 , FSK modulator  320  modulates the operating frequency of the microwave source  302  with a series of discrete frequencies to vary intensity positions of the electromagnetic energy  114  across the width of the print media  112 . That is, the physical locations of peaks and nulls of the electromagnetic energy  114  vary in a direction across the width of the print media  112 . By modulating the frequency with a series of discrete frequencies, drying performance of microwave dryer  300  is improved over other microwave dryers and may be implemented with relatively simple electrical components capable of producing binary input to control FSK modulator  320 . 
       FIG. 5  is a flow chart of a method  500  of modulating a microwave source  302  of a microwave dryer  300  with a series of discrete frequencies applied over a period of time in an exemplary embodiment. Though discussed with respect to printing system  100  of  FIG. 1  and microwave dryer  300  of  FIG. 3 , method  500  may apply to other systems. The steps of method  500  are not inclusive, may include additional or alternative steps, and may be performed in an alternate order. 
     In step  502 , processor  330  determines a period of time for print media  112  to traverse through a passageway  210  through width  312  through the short axis of waveguide  204 . The period of time is an amount of time that any given point on print media  112  is within the confines of waveguide  204  as print media  112  travels along media path  118 . The period of time is thus a function of travel speed of print media  112  and the width  312  of waveguide  204  along media path  118 . Values for the width  312  of waveguide  204  and speed of print media  112  may be retrieved from memory. For instance, processor  330  may access memory that stores an association of speed of print media  112  with particular operating/drying modes of microwave dryer  300 , print job types, print media  112  types, etc. Alternatively or additionally, processor  330  may retrieve values for the speed of print media  112  in microwave dryer  300  from a sensor, user input via a graphical user interface, print controller  104  of printer  102 , etc. As described in greater detail below, the period of time determined in step  502  may be used for modulating with FSK modulator  320  (e.g., described above in step  406 ). 
     In step  504 , processor  330  determines a modulating signal with a modulating frequency based on the period of time. Since the modulating frequency defines how quickly the operating frequency shifts, processor  330  may use the period of time determined in step  502  (e.g., the exposure time of print media  112  in waveguide  204 ) to calculate an optimal rate, or number of frequency shifts per second to perform, such that a full spectrum of frequencies transmitted by microwave source  302  occurs during the exposure time of print media  112  in waveguide  204 . That is, the operating frequency of microwave source  302  is to be modulated a frequency deviation amount within the time that it takes print media  112  to travel through the width  312  of waveguide  204  along media path  118 . 
     In step  506 , processor  330  determines a number of frequencies that approximate the modulating signal at the modulating frequency. With the modulating frequency determined in step  504 , processor  330  may calculate a minimum number of discrete levels to which the modulating signal may be quantized to sufficiently vary the operating frequency to the desired accuracy. Alternatively or additionally, processor  330  may access memory that stores an association of a number of discrete frequencies for various values of modulating frequencies. Processor  330  may also determine a frequency value for each of the discrete frequencies based at least in part on a desired frequency deviation amount. For example, for a microwave source that operates at 2.45 GHz, it may be desirable to deviate the operating frequency+/−10 MHz so that it oscillates between 2.46 GHz and 2.44 GHz. However, alternative frequency deviation amounts may be implemented between a minimum value that is able to provide a desired uniformity of the electrical field within waveguide  204  and a maximum value which does not exceed a cost of technology components which are able to implement rapid modulation/variation of the operating frequency. 
     In step  508 , processor  330  applies binary values that represent the number of frequencies to an input of FSK modulator  320  to cause FSK modulator  320  to output the series of discrete frequencies over the period of time. Since each discrete frequency may be represented by a combination of bits, processor  330  may convert a value of each discrete frequency (e.g., determined in step  506 ) into a binary format that is compatible with a desired output at FSK modulator  320 . Processor  330  may also determine/calculate a constant or varying transmit period for each of the binary values based on the period of time and the number of frequencies. In one embodiment, the transmit period may be determined based by dividing the time period from step  502  by the number of frequencies from step  506  yielding a constant value. In other embodiments the transmit period may be variable to facilitate drying of certain regions of the print media  112 . Since the amplitude of the modulating signal defines a deviation amount in the operating frequency, the amplitude of the modulating signal (and thus the deviation amounts in the operating frequency of microwave source  302 ) may fluctuate across consecutively transmitted discrete frequencies while the transmit period for consecutively transmitted discrete frequencies is constant. 
     By using FSK modulation according to method  500  described above, microwave dryer  300  may implement a customizable amount of sweep in the operating frequency of microwave source  302 . The deviation amount and rate of change in the operating frequency may be adapted to various print/drying considerations, such as the speed of print media  112 , type of print media  112 , amounts of ink applied to print media by print controller  104 , type of print job or print data  110 , etc. Additional examples and points of illustration are described below. 
       FIG. 6  illustrates a plot of a modulating signal in an exemplary embodiment. Assume, for this example, that microwave source  302  operates at 2.45 GHz, and that print media  112  has a travel speed through microwave dryer of 150 meters/minute and width  312  of microwave waveguide  204  is 4.3 cm. From this, processor  330  may determine that print media  112  has an exposure time of 17.2 milliseconds traversing through each microwave waveguide  204 . Processor  330  may then select a modulating frequency that is capable of supporting a full spectrum of frequency shifts within 17.2 milliseconds. In this example, the modulating signal  610  has a frequency of 50 Hz and a period of 0.02 seconds, or 20 milliseconds, and thus can support a full spectrum of frequency shifts within 17.2 milliseconds. Processor  330  therefore determines to use a modulating signal  610  with a modulating frequency of 50 Hz. 
     Further assume for this example that a frequency deviation of +/−10 MHz for microwave source  302  is desired. Thus, the 50 Hz modulating signal  610  is to swing microwave source  302  between 2.46 GHz and 2.44 GHz about its center operating frequency of 2.45 GHz, as shown in plot  600 . From this, processor  330  may quantize the modulating signal  610  into a series of discrete frequencies  620 - 630  to approximate the modulating signal  610  in binary form. In the process of converting the modulating signal  610  into a series of discrete frequencies  620 - 630 , processor  330  may determine that eleven unique frequencies is the minimum number of discrete frequencies  620 - 630  to sufficiently approximate modulating signal  610  (and to sufficiently vary microwave source  302 ). Each discrete frequency is represented by a combination of bits (e.g., 4 bits to control FSK modulator  320  to output sixteen possible different frequencies, but in this case using just eleven of sixteen binary combinations) that indicate an amplitude value (which defines an amount of shift in operating frequency) and processor  330  may set the rate of shifts in the operating frequency by controlling FSK modulator  320  transmit discrete frequencies  620 - 621  in discrete intervals as shown in plot  600 . That is, processor  330  may calculate a transmit period (i.e. transmission duration) of 1 millisecond for each of the binary values such that a full spectrum of the eleven unique discrete frequencies  620 - 630  (e.g., defined by a half period of modulating signal  610 ) may occur within the exposure time of 17.2 milliseconds. As shown in plot  600 , processor  330  may transmit the discrete frequencies  620 - 630  to FSK modulator  320  (and/or cause FSK modulator  320  to transmit/apply discrete frequencies  620 - 630  to microwave source  302 ) in even or varying transmit periods (i.e. bit durations) and uneven amplitudes. 
       FIG. 7  illustrates an intensity plot  710  and a field strength plot  720  according to an FSK modulation of microwave source  302  using eleven discrete frequencies in an exemplary embodiment. In continuing with the example described above with respect to  FIG. 6 , the application of eleven discrete frequencies  620 - 621  to modulate microwave source  302  results in reduced variation in (i.e., a relatively constant) intensity  712  (expressed as power per unit area or (V/m) squared) along the long axis of waveguide  204  (and continuing along the long axis of any additional waveguides coupled thereto) thereby providing uniform heating across the width  310  of print media  112  or media path  118 . Similarly, the e-field strength plot  720  (expressed as volts per meter) shows an even distribution down the length of several waveguides (e.g., each waveguide approximately 70 cm in length). 
       FIG. 8  illustrates a plot of a modulating signal approximated with three unique frequencies in an exemplary embodiment. Suppose that all exemplary values described with respect to  FIG. 6  remain the same except the number of frequencies to represent the modulating signal  610  is three instead of eleven. Here, fewer bits may be used to control FSK modulator  320  (e.g., 2 bits to control FSK modulator  320  to output four possible different frequencies) and each bit or discrete frequency transmission period is longer compared with the eleven unique frequency example described above. However, the resulting frequency sweep of microwave source  302  may produce an insufficient distribution of the operating frequency in waveguide  204  depending on the particular desired parameters of microwave dryer  300 . Therefore, processor  330  may determine a number of discrete frequencies to use that minimizes the operating resources of processor  330 , FSK modulator  320 , and/or components thereof (e.g., according to processing speeds, capacity, etc.) while still performing a threshold number of frequency shifts to sufficiently vary microwave source  302  output microwaves. 
       FIG. 9  illustrates an intensity plot  910  and a field strength plot  920  according to an FSK modulation of microwave source  302  using three discrete frequencies in an exemplary embodiment. As shown in intensity plot  910 , the use of three discrete frequencies to modulate the 2.45 GHz operating frequency of microwave source  302  as compared with the eleven discrete frequencies results relatively large distances between intensity peaks along the long axis of waveguide  204  (and continuing along the long axis of any additional waveguides coupled thereto), resulting in a pattern of high energy areas  912  and low energy areas  914  spaced along waveguide  204  and across the width of print medium  112 . Similarly, the field strength plot  920  shows that the long axis of waveguide  204  has a relatively uneven distribution in comparison with  FIG. 7 . Thus, the fewer number of discrete frequencies used may produce a lower than desired drying performance in microwave dryer  300 . 
     Embodiments disclosed herein can take the form of software, hardware, firmware, or various combinations thereof. In one particular embodiment, software is used to direct a processing system of microwave dryer  300  to perform the various operations disclosed herein.  FIG. 10  illustrates a processing system  1000  operable to execute a computer readable medium embodying programmed instructions to perform desired functions in an exemplary embodiment. Processing system  1000  is operable to perform the above operations by executing programmed instructions tangibly embodied on computer readable storage medium  1012 . In this regard, embodiments of the invention can take the form of a computer program accessible via computer-readable medium  1012  providing program code for use by a computer or any other instruction execution system. For the purposes of this description, computer readable storage medium  1012  can be anything that can contain or store the program for use by the computer. 
     Computer readable storage medium  1012  can be an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor device. Examples of computer readable storage medium  1012  include a solid state memory, a magnetic tape, a removable computer diskette, a random access memory (RAM), a read-only memory (ROM), a rigid magnetic disk, and an optical disk. Current examples of optical disks include compact disk-read only memory (CD-ROM), compact disk-read/write (CD-R/W), and DVD. 
     Processing system  1000 , being suitable for storing and/or executing the program code, includes at least one processor  1002  coupled to program and data memory  1004  through a system bus  1050 . Program and data memory  1004  can include local memory employed during actual execution of the program code, bulk storage, and cache memories that provide temporary storage of at least some program code and/or data in order to reduce the number of times the code and/or data are retrieved from bulk storage during execution. Some examples of processors include Intel® Core™ processors, Advanced Reduced Instruction Set Computing (RISC) Machines (ARM®) processors, etc. Memory may additionally or alternatively include any hardware device that is able to store data, such as one or more volatile or non-volatile Dynamic Random Access Memory (DRAM) devices, FLASH devices, volatile or non-volatile Static RAM devices, hard drives, Solid State Disks (SSDs), etc. Some examples of non-volatile DRAM and SRAM include battery-backed DRAM and battery-backed SRAM. 
     Input/output or I/O devices  1006  (including but not limited to keyboards, displays, pointing devices, etc.) can be coupled either directly or through intervening I/O controllers. Network adapter interfaces  1008  may also be integrated with the system to enable processing system  1000  to become coupled to other data processing systems or storage devices through intervening private or public networks. Modems, cable modems, IBM Channel attachments, SCSI, Fibre Channel, and Ethernet cards are just a few of the currently available types of network or host interface adapters. Display device interface  1010  may be integrated with the system to interface to one or more display devices, such as printing systems and screens for presentation of data generated by processor  1002 . 
     Although specific embodiments were described herein, the scope of the invention is not limited to those specific embodiments. The scope of the invention is defined by the following claims and any equivalents thereof.