Patent Publication Number: US-2007109568-A1

Title: Method and apparatus for printing an image

Description:
BACKGROUND  
      Electrophotographic printers employ lasers or light emitting diodes to print images onto a page. Electrophotographic color printers operate by using a select set of colors which are referred to as a color model. One color model that is used is the cyan-magenta-yellow-black (CMYK) color model. To print an image onto a page, the CMYK colors are applied to the page using subtractive color mixing to subtract colors from the white background of the page, thereby allowing light reflected from the page to have the desired colors. Although cyan, magenta and yellow in equal amounts will print black, black toner is used to achieve higher quality printing.  
      To print an image in a CMYK color space, each of the colors in the CMYK color model is represented numerically by levels that describe the intensity of the color. One approach uses  8  bits per color per pixel to define one of 256 levels of intensity. By combining the colors when using one of the 256 levels of intensity to describe each color, any desired color can be achieved.  
      Electrophotographic color printers typically operate in a page mode and print images in one page increments. The image information to be printed is typically contained in a single file that includes, for each color, one page of information that defines how the color will be applied to the page. These pages of information, referred to as color planes, are typically aligned before being sent to the printer so that the proper intensity of each color will be applied at each location on the page.  
      Since the resolution of laser printers can exceed 2400 dots per inch (dpi), the memory storage capacity required by the printer to store the aligned color planes can be significant. Standard image compression techniques such as JPEG (the standard written by the Joint photographic Experts Group) are typically used to lower this requirement. However, even with compression, the memory capacity required by the printer to store the image in the CMYK color space can still be significant.  
      With in-line laser printers, the memory storage requirement can increase significantly. In-line laser color printers typically use four lasers (one for each of the CYMK colors) to place an image on a page while moving the page through the printer in one direction. An image sent from a host to the in-line laser printer is typically defined in a Red-Green-Blue (RGB) color space, and the in-line laser printer converts the image from the RBG color space to the CYMK color space. Since the lasers can apply colors to different portions of a page or to different pages at the same time, each image hardware path for each laser typically stores a complete copy of the image for multiple pages. If image compression is used, each image hardware path decompresses the RGB image before performing color space conversion from RGB to CYMK. Thus electrophotographic color printers, and in-line laser color printers in particular, typically employ significant amounts of memory as well as decoding hardware to perform color space conversion.  
      For these and other reasons, this is a need for the present invention.  
     SUMMARY  
      One aspect of the invention provides a method for printing an image. The method comprises separating the image into colors, partitioning each one of the colors into data blocks, and transferring the data blocks to a printer. The data blocks are transferred in an order that the printer will apply the colors to a print medium by transferring, before each one of a plurality of time intervals, one of the data blocks for each one of the colors that will be applied to the print medium during the one of the plurality of time intervals. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a block diagram illustrating one embodiment of an image processing system.  
       FIG. 2  is a diagram illustrating one embodiment of an electrophotographic printer.  
       FIG. 3  is a diagram illustrating one embodiment of an application of colors to a print medium by an electrophotographic printer as a function of time.  
       FIG. 4  is a diagram illustrating one embodiment of a transfer of data blocks to an electrophotographic printer in an order that the printer will apply the colors to a print medium. 
    
    
     DETAILED DESCRIPTION  
      In the following Detailed Description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as “top”,“bottom”, “front”,“back,” “leading,” “trailing,” etc. is used with reference to the orientation of the Figures(s) being described. Because components of embodiments of the present invention can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following Detailed Description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.  
       FIG. 1  is a block diagram illustrating one embodiment of an image processing system  10 . Image processing system  10  includes a host  12  and an electrophotographic printer  26 . In the illustrated embodiment, host  12  includes a controller  14 , a compressor  16 , driver  18  and an I/O port  20 , all of which are coupled to a bus  22 . Printer  26  includes I/O port  28 , decompressor  30 , buffer memory  32 , print controller  34  and image paths  36 , all of which are coupled to a bus  38 . Printer  26  is coupled to host  12  via bus  24 . Bus  24  is coupled between I/O port  20  and I/O port  28 .  
      In the illustrated embodiment, controller  14  converts an image from the red-green-blue (RGB) color space to the cyan-magenta-yellow-black (CYMK) color space before sending the image to printer  26 . Host  12  retains images in the RGB color space format because information is displayed by host  12  using additive color mixing with red, green and blue. The image in the CYMK color space is separated into cyan, yellow, magenta and black colors or color planes.  
      In the illustrated embodiment, controller  14  is configured to separate or partition an image to be printed into separate colors and to partition each one of the colors into data blocks  72 ,  74 ,  76 ,  78 ,  80 ,  82 ,  84  or  86  that define how printer  26  will apply the colors to print medium  54 . Compressor  16  reduces the size of data blocks  72 ,  74 ,  76 ,  78 ,  80 ,  82 ,  84  or  86  by using a suitable standard image compression technique (e.g., JPEG (the standard written by the Joint Photographic Experts Group) or JBIG (the standard written by the Joint Bi-level Image Expert Group)). While JPEG and JBIG each have certain advantages, such as JPEG has the advantage of being able to store 24 bits/pixel for a total of 16,777,216 possible colors, in other embodiments, the data blocks  72 ,  74 ,  76 ,  78 ,  80 ,  82 ,  84  or  86  are not compressed or are compressed using other suitable approaches.  
      In the illustrated embodiment, driver  18  sends data and instructions between host  12  and printer  26 . Data blocks  72 ,  74 ,  76  and  78  are provided by host  12  to printer  26  via driver  18  and I/O port  20  through time interval T 9 , and data blocks  80 ,  82 ,  84  and  86  are provided by host  12  to printer  26  via driver  18  and I/ 0  port  20  through time interval T 16 . The data blocks are provided in the order that printer  26  will apply the colors to print medium  54 . That is, before each one of the time intervals T, one or more data blocks  72 ,  74 ,  76 ,  78 ,  80 ,  82 ,  84  or  86  are received from host  12  that define how the image paths  36  will apply the colors to the print medium  54  during the time interval T.  
      In the illustrated embodiment, before each one of the time intervals T 1  through T 9  for page 1 and time intervals T 8  through T 16  for page 2, one of the data blocks  72 ,  74 ,  76 ,  78 ,  80 ,  82 ,  84  or  86  is transferred to the printer for each one of the colors that is applied to print medium  54  during the time intervals TI through T 16 . In this embodiment, the CMYK color model is used and the colors applied to the print medium are cyan (data blocks  72  and  80 ), yellow (data blocks  74  and  82 ), magenta (data blocks  76  and  84 ) and black (data blocks  78  and  86 ). In other embodiments, other suitable color models and colors can be used. In other embodiments, the print medium can be paper or can include any suitable surface area upon which colors can be applied.  
      In the illustrated embodiment, electrophotographic printer  26  is an in-line color laser printer. In other embodiments, electrophotographic printer  26  can be other suitable types of printers such as a Light Emitting Diode (LED) printer. In this embodiment, the in-line color laser printer  26  applies the colors in an order to print medium  54  as print medium  54  is moved through printer  26 . Printer  26  uses image path  36   a  for cyan, image path  36   b  for yellow, image path  36   c  for magenta and image path  36   d  for black. Each image path includes a laser which is used to apply one of cyan, yellow, magenta or black to print medium  54 . While only cyan, yellow and magenta are required to print a color image on print medium  54 , the use of black helps create a higher quality image. Each image path  36  applies either cyan, yellow, magenta or black to the print medium  54  for a time period that includes consecutive time intervals to form the image. Each time period for each one of the image paths begins at different times. Because printer  26  is an in-line printer, in this embodiment, the colors are applied to print medium  54  while moving the print medium  54  through printer  26  in only one direction.  
      In the illustrated embodiment, decompressor  30  decompresses the data blocks  72 ,  74 ,  76 ,  78 ,  80 ,  82 ,  84  or  86  so that they can be used in an uncompressed format. In other embodiments, the data blocks  72 ,  74 ,  76 ,  78 ,  80 ,  82 ,  84  or  86  are not compressed by host  12 . In other embodiments, any suitable compression and decompression approach can be used by compressor  16  and decompressor  30 , respectively. In the illustrated embodiment, buffer memory  32  stores any of the data blocks  72 ,  74 ,  76 ,  78 ,  80 ,  82 ,  84  or  86  that are to be printed either before the printing begins or while the printer is printing other information. If compression is used, less storage space is needed by buffer memory  32 .  
      In the illustrated embodiment, print controller  34  controls the print quality and speed of printer  26 . Print controller  34  communicates with host  12  via bus  24  to determine how information will be exchanged between host  12  and printer  26  and to determine how the data blocks  72 ,  74 ,  76 ,  78 ,  80 ,  82 ,  84  or  86  will be applied to print medium  54 . In various embodiments, bus  24  can be any suitable communications interface such as a parallel port, a USB port (the standard by the USB Implementers Forum), firewire or network interface. I/O ports  20  and  28  are configured to send and receive information over bus  24  in accordance with the type of port used. In the illustrated embodiment, print controller  34  performs tasks such as storing data blocks  72 ,  74 ,  76 ,  78 ,  80 ,  82 ,  84  or  86  in buffer memory  32  as needed and can perform other suitable tasks such as organizing and storing multiple printing requests into a queue. Print controller  34  communicates with host  12  to start and stop the transfer of information and to organize the data blocks  72 ,  74 ,  76 ,  78 ,  80 ,  82 ,  84  or  86  once they are received. Print controller  34  also controls image paths  36  and the application of the information in the data blocks to print medium  54 . Print controller  34  also can control such items as page formatting, font handling etc.  
       FIG. 2  is a diagram illustrating one embodiment of an in-line electrophotographic printer  26 .  FIG. 2  is a simplified mechanical diagram of the printer  26  shown in  FIG. 1  and illustrates the application of the image to print medium  54 . Details regarding the electrophotographic method are omitted for clarity. In this embodiment, printer  26  includes image paths  36   a - 36   d  which respectively apply the image to corresponding drums  50   a - 50   d . Each image path  36  includes a toner cartridge for the respective color that is being applied to the corresponding drum  50  (e.g. cyan, magenta, yellow and black), and includes a laser to transfer the image. Image paths  36  transfer the image to corresponding drums  50  by using the lasers to discharge portions of corresponding drums  50  so that the toner for the colors can be applied to the corresponding drums  50 . Image path  36   a  transfers cyan to drum  50   a  at  44   a . Image path  36   b  transfers yellow to drum  50   b  at  44   b . Image path  36   c  transfers magenta to drum  50   c  at  44   c . Image path  36   d  transfers black to drum  50   d  at  44   d . In one embodiment, the spacing between application areas  44   a ,  44   b ,  44   c  and  44   d  is approximately two inches. In other embodiments, this spacing can be any suitable amount. In various embodiments, the lasers have a resolution that can range from less than 300 dots per inch (dpi) to greater than 1,200 dpi. Although each of the colors are individually applied to the corresponding drums  50 , in the illustrated embodiment, the colors are overlapping and are combined to form the image which is transferred to print medium  54  via drums  50 .  
      In the illustrated embodiment, drums  50   a - 50   d  rotate in the direction indicated by arrows  52 . As drums  50  rotate in the direction indicated by arrows  52 , the image surface area or the portion of the corresponding drums  50   a  - 50   d  that the image is being transferred to will move past the corresponding application areas  44   a ,  44   b ,  44   c  and  44   d . In one embodiment, cyan is the first color to be applied and black is the last color to be applied. As the colors are overlapping and are combined to form the image, other suitable orders of color application can be used in other embodiments. In the illustrated embodiment, as drum  50   a  rotates in the direction indicated by arrows  52 , image data to transfer cyan to drum  50   a  is first required for cyan at  44   a . At  44   b , image data to transfer yellow to drum  5 O b  is first required and additional information is required for cyan. At  44   c , image data to transfer magenta to drum  50   c  is first required and additional information is required for yellow and cyan. At  44   d , image data to transfer black to drum  50   d  is first required and additional information is required for magenta, yellow and cyan. As drums  50  continue to rotate, the last of the cyan image data is required before the last of the yellow, magenta and black information. The last of the yellow image data is required before the last of the magenta and black information. And the last of the magenta information is required before the last of the black information.  
      In the illustrated embodiment, print medium  54   a  is printed first and print medium  54   b  is printed second. Print medium  54   a  and  54   b  are moved from paper tray  56  by roller  58   a  and are spaced about 0.5 inches apart as they pass under drum  50 . Rollers  58   a - 58   g  guide print medium  54  under drums  50  so that the image can be transferred to print medium  54 . Print medium  54  is then moved through fuser  60  which includes a pair of heated rollers that melts the loose toner powder causing it to fuse with the fibers in print medium  54 . Print medium  54   a  and  54   b  are deposited in a paper bin after the image transfer is complete (not shown). In one embodiment, print medium  54   a  and  54   b  are sheets of paper and print medium  54   a  is the first page to be printed (e.g. page one) and print medium  54   b  is the second page to be printed (e.g. page two). In other embodiments, print medium  54  can be any suitable print medium upon which colors can be applied. Although print medium  54   a  and print medium  54   b  are illustrated, in other embodiments there can be any suitable number of print mediums, such as one or more than two.  
       FIG. 3  is a diagram illustrating one embodiment of an application of colors to a print medium  54  by electrophotographic printer  26  as a function of time. In the illustrated embodiment, host  12  converts the image from first color space image data in the RGB color space to second color space image data in the CYMK color space. Each page of information for cyan, magenta, yellow and black is referred to as a color plane. In the illustrated embodiment, 8 bits per color per pixel are used which each define 256 levels or intensities for each one of the colors. By combining the color planes when using one of the 256 levels for each color, all colors in the original image can be reproduced.  
      After separating the image into the colors of cyan, yellow, magenta and black, host  12  further divides or partitions the second color space image data for each one of the colors into color plane data files or data blocks  72 ,  74 ,  76 ,  78 ,  80 ,  82 ,  84  or  86 . Data blocks  72  and  80  contain color plane information for page one and page two, respectively, for cyan, data blocks  74  and  82  contain color plane information for page one and page two, respectively, for yellow, data blocks  76  and  84  contain color plane information for page one and page two, respectively, for magenta and data blocks  78  and  86  contain color plane information for page one and page two, respectively, for black. Host  12  transfers the data blocks to printer  26  in an order that printer  26  will apply the colors to print medium  54  by transferring, before each one of the time intervals T, one of the data blocks for each one of the colors that will be applied to the print medium by printer  26  during the time interval T. In one embodiment, the time intervals T for each of the colors are consecutive and correspond to a time that a location on print medium  54  moves from  44   a  to  44   b , from  44   b  to  44   c , or from  44   c  to  44   d.    
      The data block size does not need to line up with the time slot. For example, in one embodiment, the time between the start of the different colors is not an integer or a single time period equal to the amount of data in a block.  
      In the illustrated embodiment at  70 , sixteen time intervals T are used to apply two pages of image information to print medium  54  for each of cyan, yellow, magenta and black. The image data for each page and for each color is divided into six data blocks. In other embodiments, other suitable numbers of data blocks can be used. Because each one of the data blocks  72 ,  74 ,  76 ,  78 ,  80 ,  82 ,  84  or  86  is transferred to printer  26  in the order that the image information is contained within the data blocks, a higher number of data blocks for each page can be used if buffer memory  32  has a smaller memory storage capacity, and a smaller number of data blocks for each page can be used if buffer memory  32  has a higher memory storage capacity. In the illustrated embodiment, for each one of cyan, yellow, magenta or black, the data blocks are transferred to printer  26  for print medium  54   a  and print medium  54   b  in consecutive time intervals. For each page, each one of the colors is transferred in a number of data blocks that is the same as for every other color. Since a location on print medium  54  moves past  44   a  ,  44   b ,  44   c  and  44   d  at different times, the first data block for each color is transferred at a unique time, and the time period for transferring each of the colors begins and ends at unique times.  
      In the illustrated embodiment, each of the image paths  36  apply the respective color to corresponding drum  50  in six time intervals T for either print medium  54   a  or print medium  54   b . Thus cyan for print medium  54   a  (illustrated as page one) is applied during time intervals T 1  through T 6 , cyan for print medium  54   b  (illustrated as page two) is applied during time intervals T 8  through T 13 , yellow for page one is applied during time intervals T 2  through T 7 , yellow for page two is applied during time intervals T 9  through T 14 , magenta for page one is applied during time intervals T 3  through T 8 , magenta for page two is applied during time intervals T 10  through T 15 , black for page one is applied during time intervals T 4  through T 9 , and black for page two is applied during time intervals T 11  through T 16 .  
      In one embodiment, each one of the data blocks  72 ,  74 ,  76 ,  78 ,  80 ,  82 ,  84  or  86  contains image information for one color and for one-sixth of the image to be placed on print medium  54   a  or print medium  54   b . Since there are four colors, an image is transferred to print medium  54   a  with a total of 24 data blocks (e.g. data blocks  72 ,  74 ,  76  and  78 ), and an image is transferred to print medium  54   b  with a total of 24 data blocks (e.g. data blocks  80 ,  82 ,  84  and  86 ). In other embodiments, the image for either print medium  54   a  or print medium  54   b  can be transferred in any suitable numbers of data blocks.  
       FIG. 4  is a diagram illustrating one embodiment of the transfer of data blocks  72 ,  74 ,  76 ,  78 ,  80 ,  82 ,  84  or  86  to electrophotographic printer  26  in an order that the printer  26  will apply the colors to print medium  54 . Although the diagram at  100  illustrates a serial transfer of the data blocks, in other embodiments, the transfer of data blocks  72 ,  74 ,  76 ,  78 ,  80 ,  82 ,  84  or  86  can be in parallel between host  12  and printer  26 , or can be in any suitable combination of serial and parallel.  
      The diagram at  100  illustrates that the order of transfer begins with data block  72   a  for cyan and continues through data block  74   e  for yellow, continues with data block  76   d  for magenta and continues through data block  82   c  for yellow, and continues with data block  84   b  for magenta and continues through data block  86   f  for black. In one embodiment, each one of the data blocks  72 ,  74 ,  76 ,  78 ,  80 ,  82 ,  84  or  86  are compressed using a JPEG or JBIG algorithm by compressor  16  before being sent to printer  26 , and are decompressed by decompressor  30  before the respective colors are applied to photoconductor belt  42 . In other embodiments, other suitable compression and decompression algorithms are used or no compression is used.  
      Referring to  FIG. 3  and  FIG. 4 , before time interval T 1 , data block  72   a , which is first of six data blocks for page one of cyan, is transferred from host  12  to printer  26 . The laser for image path  36   a  is the first laser that applies a color (e.g. cyan) to a moving surface of a corresponding drum  50  (e.g. drum  50   a ). This is because the area of drum  50   a  that retains the image moves past the laser for cyan at  44   a  before the area of drum  50   b  that retains the image moves past the laser for yellow at  44   b , the area of drum  50   c  that retains the image moves past the laser for magenta at  44   c , and the area of drum  50   d  that retains the image moves past the laser for black at  44   d . In one embodiment, one of the time intervals T is equal to or less than a time that print medium  54  moves between  44   a  and  44   b ,  44   b  and  44   c , or  44   c  and  44   d.    
      Next, before time interval T 2 , data block  72   b , which is the second of six data blocks for page one of cyan, and data block  74   a , which is the first of six data blocks for page one of yellow, are transferred from host  12  to printer  26 . Before time interval T 3 , data block  72   c , which is the third of six data blocks for page one of cyan, data block  74   b , which is the second of six data blocks for page one of yellow, and data block  76   a , which is the first of six data blocks for page one of magenta, are transferred from host  12  to printer  26 . Before time interval T 4 , data block  72   d , which is the fourth of six data blocks for page one of cyan, data block  74   c , which is the third of six data blocks for page one of yellow, data block  76   b , which is the second of six data blocks for page one of magenta and data block  78   a , which is the first of six data blocks for page one of black, are transferred from host  12  to printer  26 . Before time interval T 5 , data block  72   e , which is the fifth of six data blocks for page one of cyan, data block  74   d , which is the fourth of six data blocks for page one of yellow, data block  76   c , which is the third of six data blocks for page one of magenta, and data block  78   b , which is the second of six data blocks for page one of black, are transferred from host  12  to printer  26 . Before time interval T 6 , data block  72   f , which is the sixth of six data blocks for page one of cyan, data block  74   e , which is the fifth of six data blocks for page one of yellow, data block  76   d , which is the fourth of six data blocks for page one of magenta, and data block  78   c , which is the third of six data blocks for page one of black, are transferred from host  12  to printer  26 . Before time interval T 7 , data block  74   f , which is the sixth of six data blocks for page one of yellow, data block  76   e , which is the fifth of six data blocks for page one of magenta, and data block  78   d , which is the fourth of six data blocks for page one of black, are transferred from host  12  to printer  26 . Before time interval T 8 , data block  80   a , which is the first of six data blocks for page two of cyan, data block  76   f , which is the sixth of six data blocks for page one of magenta, and data block  78   e , which is the fifth of six data blocks for page one of black, are transferred from host  12  to printer  26 . Before time interval T 9 , data block  80   b , which is the second of six data blocks for page two of cyan, data block  82   a , which is the first of six data blocks for page two of yellow, and data block  78   f , which is the sixth of six data blocks for page one of black, are transferred from host  12  to printer  26 . Before time interval T 10 , data block  80   c , which is the third of six data blocks for page two of cyan, data block  82   b , which is the second of six data blocks for page two of yellow, and data block  84   a , which is the first of six data blocks for page two of magenta, are transferred from host  12  to printer  26 . Before time interval T 11 , data block  80   d , which is the fourth of six data blocks for page two of cyan, data block  82   c , which is the third of six data blocks for page two of yellow, data block  84   b , which is the second of six data blocks for page two of magenta, and data block  86   a , which is the first of six data blocks for page two of black, are transferred from host  12  to printer  26 . Before time interval T 12 , data block  80   e , which is the fifth of six data blocks for page two of cyan, data block  82   d , which is the fourth of six data blocks for page two of yellow, data block  84   c , which is the third of six data blocks for page two of magenta, and data block  86   b , which is the second of six data blocks for page two of black, are transferred from host  12  to printer  26 . Before time interval T 13 , data block  80   f , which is the sixth of six data blocks for page two of cyan, data block  82   e , which is the fifth of six data blocks for page two of yellow, data block  84   d  which is the fourth of six data blocks for page two of magenta, and data block  86   c , which is the third of six data blocks for page two of black, are transferred from host  12  to printer  26 . Before time interval T 14 , data block  82   f , which is the sixth of six data blocks for page two of yellow, data block  84   e , which is the fifth of six data blocks for page two of magenta, and data block  86   d , which is the fourth of six data blocks for page two of black, are transferred from host  12  to printer  26 . Before time interval T 15 , data block  84   f , which is the sixth of six data blocks for page two of magenta, and data block  86   e , which is the fifth of six data blocks for page two of black, are transferred from host  12  to printer  26 . And last, before time interval T 16 , data block  86   f , which is the sixth of six data blocks for page two of black, is transferred from host  12  to printer  26 .  
      In the illustrated embodiment, the size of buffer memory  32  is minimized because the entire image to be printed on print medium  54  does not need to be stored in buffer memory  32 . The data blocks  72 ,  74 ,  76 ,  78 ,  80 ,  82 ,  84  or  86  are transferred before each time interval T as needed, thereby reducing the amount of memory required to store the image. Since the data blocks transferred from host  12  to printer  26  are in the CYMK color space, printer  26  does not have to perform color space conversion. Since each color plane for each color is divided into suitably sized data blocks, the amount of image information being managed by print controller  34  is minimized and the image information in one of the data blocks can be applied to the corresponding drum  50  before image information in another one of the data blocks is applied to another corresponding drum  50 , thereby avoiding having to switch between color planes of image data.  
      In one illustrative example, during the time in interval T 4 , if the color plane data is aligned in memory, the printer is employing data from the first four blocks of color planes for page one. Consequently, 16 blocks of data need to be present in the printer (the first four of all four colors). By contrast, with one embodiment of a non-aligned data printer according to the present invention, only the four blocks of data that actually represent data this is currently being printed on the page need to be present in the printer.  
      Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the invention. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this invention be limited only by the claims and the equivalents thereof.