Patent Publication Number: US-8113650-B2

Title: Printer having arcuate printhead

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application is a continuation of U.S. application Ser. No. 12/478,722 filed Jun. 4, 2009, now issued U.S. Pat. No. 7,946,702, which is a continuation of U.S. application Ser. No. 12/050,106 filed Mar. 17,2008, now issued U.S. Pat. No. 7,556,369, which is a continuation of U.S. application Ser. No. 11/737,726 filed on Apr. 19, 2007, now issued U.S. Pat. No. 7,364,286, which is a continuation of U.S. application Ser. No. 11/203,241, filed Aug. 15, 2005, now issued U.S. Pat. No. 7,222,941, which is a continuation of U.S. application Ser. No. 10/636,238 filed Aug. 8, 2003, now issued U.S. Pat. No. 6,966,636,which is a continuation of U.S. application Ser. No 09/662,210 filed on Sep. 15, 2000, now issued U.S. Pat. No. 6,612,240, the entire contents of which are herein incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to a modular printer. The invention relates particularly, but not necessarily exclusively, to a modular commercial printer for effecting high speed, digital, photographic quality, commercial printing. The invention relates specifically to drying equipment for a printer for aiding drying of a printed image on a web of print media. 
     BACKGROUND TO THE INVENTION 
     In high speed printing, large printing presses are daisy-chained together to print predetermined pages of publications which are then secured together to form the publications. Such printing presses occupy an extremely large volume and are very expensive. 
     The applicant has also proposed a commercial printer using a number of floor mounted printers having pagewidth print heads. This commercial printer is intended for extremely high production rates such as up to five 180 page documents per second. 
     To achieve such high production rates, large quantities of consumables need to be readily available for the printers. Thus, once again, such a commercial printer needs to occupy an extremely large volume although the cost of such a printer is considerably lower than equivalent high end, commercial printers which do not use the applicant&#39;s Memjet (Memjet is a trade mark of Silverbrook Research Pty Ltd) technology. 
     The applicant has recognised a need for a commercial printer which occupies a smaller volume and which has a lower through put rate but of the same quality as the applicant&#39;s previously proposed Memjet commercial printer. 
     SUMMARY OF THE INVENTION 
     According to an aspect of the present disclosure, a printer comprises a housing having an upper cover, a lower cover, a first side wall and a second, opposed side wall; a print engine housed within the housing, the print engine having two pairs of print heads arranged in opposed relationship across a print media feed path, each of the print heads having an arcuate portion in the vicinity of the print media feed path; an inlet roller assembly for feeding media into the housing; and an exit roller assembly for feeding the media out of the housing. A spacing between the print engine and the exit roller assembly is approximately one meter, whereby a duration of one second is afforded for the drying of ink at a media feed speed of approximately 0.8 meters per second. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is now described by way of example with reference to the accompanying drawings in which: 
         FIG. 1  shows a three dimensional view of a printer, in accordance with the invention; 
         FIG. 2  shows a plan view of the printer; 
         FIG. 3  shows a side view of the printer; 
         FIG. 4  shows an end view of the printer; 
         FIG. 5  shows a three dimensional view of a printer stack, in accordance with one embodiment of the invention; 
         FIG. 6  shows a three dimensional view of a printer stack, in accordance with another embodiment of the invention; 
         FIG. 7  shows a three dimensional view of the printer including its fluid connections; 
         FIG. 8  shows a detailed, three dimensional view of part of the printer; 
         FIG. 9  shows a three dimensional, exploded view of the printer; 
         FIG. 10  shows a three dimensional view of a print engine of the printer; 
         FIG. 11  shows a sectional end view of the print engine; 
         FIG. 12  shows, on an enlarged scale, part of the print engine; 
         FIG. 13  shows a three dimensional view of one of the print head assemblies of the print engine; 
         FIG. 14  shows a three dimensional, exploded view of one of the print head assemblies; 
         FIG. 15  shows a sectional side view of a print media loading mechanism of the printer, in its loading configuration; 
         FIG. 16  shows a sectional side view of the loading mechanism of the printer in its open, non-loading configuration; 
         FIG. 17  shows a three dimensional view of the loading mechanism in its non-loading configuration; and 
         FIG. 18  shows a three dimensional, exploded view of the loading mechanism in its loading configuration. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Referring to the drawings, reference numeral  10  generally designates a printer, in accordance with the invention. The printer  10  is a modular printer to be used in combination with other, identical printers, as will be described in greater detail below for effecting high speed, digital, photographic quality, commercial printing. Arrays of the printers  10  can be combined to provide scalable printing systems. However, single printers  10  may also be used individually, if desired. 
     The printer  10  comprises a housing  12 . The housing  12  is made up of an upper cover  14 , a lower cover  16  ( FIG. 9 ), a first side wall  18  and a second, opposed side wall  20  ( FIG. 9 ). Each side wall  18 ,  20  terminates in an end cap or cheek molding  22 . Each cheek molding  22  is the same to reduce the costs of production of the printer  10 . Each cheek molding  22  has a slot in which an application-specific insert  24  is received. 
     The housing  12  surrounds a frame  26 . Internal components of the printer  10  are supported on the frame  26 . 
     Opposed cheek moldings  22  at each end of the housing  12  support a guide roller  28  adjustably between them. Thus, each cheek molding  22  defines an arcuate slot  30  within which an axle of its associated roller  28  is received. 
     As described above, it is intended that, for commercial printing applications, a plurality of the printers  10  will be used together. As illustrated in  FIGS. 5 and 6  of the drawings, the printers  10  are stacked together to form a stack  40 . In the embodiment illustrated at  FIG. 5 , the stack  40  is arranged on a support table  42 . A lowermost printer  10  in the stack  40  is locked to the table  42  by means of locking feet  44  of the printer  10 . The locking feet  44  of each subsequent printer  10  in the stack  40  are received in associated holes  46  in a top of a subjacent printer  10 . Each locking foot  44  has a bayonet fitting so that, when the foot  44  is inserted into one of the holes  46  of the subjacent printer or the table  42 , as the case may be, a quarter turn of the foot  44  locks the upper printer  10  with respect to the subjacent printer  10  or the table  42 . 
     As illustrated in  FIG. 5  of the drawings, the printers  10 , when stacked horizontally, may be offset with respect to each other by locking the locking feet  44  of one printer  10  into the appropriate holes  46  of the subjacent printer. Hence, a plurality of serially aligned holes  46  is arranged adjacent each cheek molding  22 . By appropriate selection of the holes  46 , the requisite degree of offset, if any, can be achieved. 
     The offset stacking of the printers  10  allows print media, such as paper  48 , to be fed from unwinders (not shown) into each of the printers  10  at a predetermined angle and to be fed out of the printers  10  at a suitable exit angle. If the paper  48  is to be fed in and out of the printers  10  horizontally, the printers  10  of the stack  40  are vertically aligned with respect to each other. 
     In  FIG. 6 , another embodiment of the stack  40  is shown. In this embodiment, the printers  10  are arranged vertically and are spaced horizontally with respect to each other. In the example illustrated, paper  48  is fed into each printer  10  at an upper end of the printer and is fed out, after printing, through a bottom of each printer  10 . The stack  40  is supported on a framework  49  with the printer at one end of the stack  40  being locked to an end plate  51  of the framework  49  via its locking feet  44 . Adjacent printers  10  in the stack  40  are locked together by inserting the locking feet  44  of one printer  10  into the appropriate holes  46  of the adjacent printer  10 . A control console  54  is provided for controlling operation of the printer stack  40 . 
     Each printer  10  communicates with its controller and with other printers in the stack  40  via a USB2 connection  50  received in a double USB port arrangement  52 . The port arrangement  52  has an inlet port and an outlet port for enabling the printers  10  of the stack  40  to be daisy-chained together and to communicate with each other. 
     Each printer includes a print engine  56  made up of a pair of opposed print head assemblies  54  for enabling double-sided printing to be effected. The print head assembly  54  ( FIG. 11 ) of the print engine  56  of the printer  10  can print in up to twelve colors. As will be described in greater detail below, each print head assembly  54  is a duplexed print head so that, if desired, six colors, duplicated, can be printed by each print head assembly  54 . Ink is fed to the print engine  56  via an ink coupling box  58 . The coupling box  58  supports twelve ink couplings  60  thereon. Ink hoses  64  are coupled to the coupling box  58  via the couplings  60  and communicate with the print head assemblies  54  of the print engine  56  via an ink connector  62  ( FIG. 9 ). A power connection port  66  is also supported on the ink coupling. The port  66  is received through an opening  68  in one of the inserts  24  of one of the cheek moldings  22 . The same insert  24  supports an air coupling  70 . An air hose  72  ( FIG. 7 ) feeds air to the print head assemblies  54  of the print engine  56  to maintain print head nozzles (not shown) of the print head assemblies  54  free of debris and foreign matter. 
     A roller assembly  74  is mounted at an inlet end of the printer  10 . The roller assembly  74  includes a drive roller  76  and a driven roller  78 . The drive roller  76  is driven by a drive motor  80  supported on a metal bracket  82 . The metal bracket  82  is mirrored by a corresponding bracket  84  at an opposed end of the roller assembly  74 . The brackets  82  and  84  are supported on the frame  26 . 
     In addition, a similar, exit roller assembly  86  is provided at an outlet end of the printer  10 . Once again, the roller assembly  86  has a drive roller  88  driven by a drive motor  90  and a driven roller  92 . The rollers  86  and  92  are supported between metal brackets  94  and  96 . The brackets  94  and  96  are secured to the frame  26 . The bracket  94  also supports the motor  90 . 
     The drive roller  76  drives the driven roller  78  via a set of helical gears  132 . A similar arrangement applies in respect of the roller  88  and  92  of the roller assembly  86 . 
     The cheek molding  22 , at the inlet end of the printer  10 , opposite the molding  22  supporting the air coupling  70 , also supports a USB control PCB  98 . 
     The print engine  56  is supported by a chassis comprising a pair of opposed metal brackets  100 ,  102  mounted downstream (in a direction of feed of the paper) of the roller assembly  74 . Each metal bracket  100 ,  102  supports one of the print head assemblies  54  of the print engine  56 . 
     The print engine  56  is shown in greater detail in  FIGS. 10 to 12  of the drawings. As described above, the print engine  56  comprises two print head assemblies  54 . The print head assemblies  54  are arranged in opposed relationship to enable double sided printing to be effected. In other words, the paper  48  passes between the print head assemblies  54 . The brackets  100 ,  102  support the print head assemblies  54  and position the print head assemblies  54  approximately 0.75 mm apart from the web of paper  48 . This distance is automatically adjusted by the brackets  100 ,  102  to maintain constant spacing with varying paper thickness. 
     In addition, as will be described in greater detail below, print heads of the print head assemblies  54  are so designed as to allow for close proximity to the rollers  76  and  78  resulting in a closely controlled paper to print head gap. 
     Each print head assembly  54  comprises a first print head  104  and a second, adjacent print head  106 . Each print head  104 ,  106 , further, is made up of two modules  104 . 1  and  104 . 2  and  106 . 1  and  106 . 2 , respectively. 
     The modules  104 . 1  and  106 . 1  are coupled together and are controlled by a first printed circuit board (PCB)  108 . Similarly, the modules  104 . 2  and  106 . 2  are coupled together and are controlled by a second printed circuit board (PCB)  110 . PCB&#39;s  108  and  110  communicate with print head chips  112  of the print heads  104  and  106  via flex PCB&#39;s  114 . These flex PCB&#39;s  114  terminate in terminal pads  116  on moldings  118  of the modules  104 . 1 ,  104 . 2 ,  106 . 1  and  106 . 2  of the print heads  104  and  106 . The terminal pads  116  communicate with corresponding pads (not shown) of the PCB&#39;s  108 ,  110 . 
     It is to be noted that the moldings  118  are mirror images of each other, each having ink inlets  120  at a free end thereof. Ink is fed in at one end of interconnected moldings  118  only so that the inlets  120  not being used are plugged by appropriate plugs. Also, the PCB&#39;s  108 ,  110  are mirror images of each other. This reduces the cost of production of the printer  10  and also enables rapid and easy assembly of the printer  10 . The PCB&#39;s  108  and  110  communicate with each other via a serial cable  122 . One of the PCB&#39;s  108 ,  110  is connected via a connector  124  to the USB circuit board  98 . 
     Each PCB  108 ,  110  includes two print engine controllers (PEC&#39;s)  126  and associated memory devices  128 . The memory devices  128  are dynamic random access memory (DRAM) devices. 
     The molding  118  of each print head assembly  54  is supported on the frame  100 ,  102  via an end plate  130  ( FIG. 13 ). 
     The print engine  56  is shown in greater detail in  FIG. 11  of the drawings. The print engine  56  comprises the two print head assemblies  54 . As previously described, each print head assembly  54  comprises two print heads  104 ,  106 . Each print head  104 ,  106  has a print head chip  112  associated therewith. The print head chips  112  of the print heads  104 ,  106  are supported along a longitudinal edge portion of the moldings  118 . The edge portion of each molding  118  which carries the print head chip  112  is arcuate. The arcuate portion of each molding  118  has a radius of curvature which approximates that of the radius of the rollers  76 ,  78 . This design of the print heads  104 ,  106  allows for close proximity of the print head chips  112  to the rollers  76 ,  78  resulting in a closely controlled paper to print head gap. In so doing the printhead chip  112  prints in a portion of the paper, which is taut, resulting in a more accurate deposition of ink drops on the paper  48 . 
     As illustrated more clearly in  FIG. 12  of the drawings, an air channel  138  is arranged adjacent each print head chip  112  for feeding air to the print head chip  112  from the air hose  72 . 
     With this arrangement of print head assemblies  54 , either six colors or twelve colors can be printed. Where six colors are to be printed, these are duplicated in the print heads  104 ,  106  of each assembly  54  by having the appropriate colored ink or related matter (referred to for convenience as “colors”) in the relevant galleries  136  of the moldings  118 . Instead, each print head assembly  54  can print the twelve “colors” having the appropriate “colors” charged into the galleries  136  of the print heads  104 ,  106 . Where six “colors” are to be printed, these are normally cyan, magenta, yellow and black. The remaining galleries  136  then have an ink fixative and a varnish. Where twelve “colors” are to be printed, the “colors” are cyan, magenta, yellow, black, red, green, blue, either three spot colors or two spot colors and infrared ink, and the fixative and the varnish. 
     The printer  10  is designed so that, where six “colors” are to be printed, the printer can print at a printing speed of up to 1,360 pages per minute at a paper speed of 1.6 m/s. Where twelve “colors” are to be printed, the printer  10  is designed to operate at a printing speed of up to 680 pages per minute at a paper speed of 0.8 m/s. 
     The high speed is achieved by operating the nozzles of the print head chips  112  at a speed of 50,000 drops per second. 
     Each print head module  104 . 1 ,  104 . 2 ,  106 . 1 ,  106 . 2  has six nozzle rows per print head chip  112  and each print head chip  112  comprises 92,160 nozzles to provide 737,280 nozzles per printer. It will be appreciated that, with this number of nozzles, full 1600 dpi resolution can be achieved on a web width of 18.625 inches. The provision of a web width of this dimension allows a number of pages of a document to be printed side-by-side. 
     In addition, matter to be printed is locally buffered and, as a result, complex documents can be printed entirely from the locally buffered data. 
     It is also intended that the amount of memory  128  installed on each board  108 ,  110  is application dependent. If the printers  10  are being used for unchanging pages, for example, for offset press replacement, then 16 megabytes per memory module is sufficient. If the amount of variability on each page is limited to text, or a small range of variable images, then 16 megabytes is also adequate. However, for applications where successive pages are entirely different, up to 1 gigabyte may need to be installed on each board  108 ,  110  to give a total of 4 gigabytes for the print engine  56 . This allows around 2,000 completely different pages to be stored digitally in the print engine  56 . The local buffering of the data also facilitates high speed printing by the printers  10 . 
     The spacing between the print engine  56  and the exit roller assembly  86  is approximately one meter to allow for a one second warm-set ink drying time at a web speed of the paper  48  of approximately 0.8 meters per second. To facilitate drying of the printed images on the paper  48  the fixative is used in one of the ink galleries  136 . In addition, warm air is blown into the interior of the printer  10  from a source (not shown) connected to an air inlet  140  ( FIG. 1 ) via an air hose  142 . The air inlet communicates with a metal air duct  144  ( FIG. 9 ) which blows the warm air over the paper  48  exiting the print engine  56 . Warm air is exhausted from the interior of the printer by means of vents  146  in the side wall  20  of the housing  12  of the printer  10 . 
     The printer  10  includes a print media loading mechanism  150  for loading the paper  48  into the interior of the printer  10 . The loading mechanism  150 , comprises a pair of opposed endless belts  152  (shown more clearly in  FIGS. 15 to 18  of the drawings). Although not illustrated as such, these belts  152  are foraminous to enable the warm air ducted in through the duct  144  to be blown through the belts  152  over both surfaces of the paper  48 , after printing, in use. 
     Each belt  152  passes around a pair of spaced rollers  154 . The rollers  154  are held captive to be vertically slidable in slides  156 . The slides  156  are mounted on the frame  26  of the printer  10 . 
     Each roller  154  is mounted at one end of an arm  158 . The opposed end of each arm  158  is connected at a common pivot point  160  to a traverser block  162  so that the arms  158  are connected to their associated traverser block  162  scissors-fashion. The traverser block  162  is, in turn, mounted on a lead or worm screw  164 . The worm screw  164  is rotatably driven by a motor  166  supported on a bracket  168 . 
     The rollers  154  are driven by a motor  170  ( FIG. 18 ). 
     When it is desired to load paper  48  into the printer  10 , the mechanism  150  is operated by a paper load button  172  ( FIGS. 1 and 8 ). This causes the roller motor  170  to be activated as well as the motor  166 . Rotation of the motor  166  causes the traverser blocks  162  to move in the direction of arrows  174  to bring the belts  152  into abutment with each other. A leading edge of the paper  48  is fed between the belts  152 , is grabbed by the belts  152  and is fed through the printer  10  to exit through the exit roller assembly  86 . Once the paper  48  has been loaded, the direction of the motor  166  is reversed so that the traverser blocks move in directions opposite to that of arrows  174  causing the belts  152  to move to the position shown in  FIG. 16  of the drawings. Thus, during printing, the belts  152  are spaced from, and do not bear against, surfaces of the paper  48 . 
     Accordingly, by means of the invention, a modular printer which can print at commercial printing speeds is provided for the printing of documents. Several modules can be arrayed in combination with inserting machines for published documents, such as magazines, with variable paper weights. In addition, print module redundancy allows paper splicing on a stopped web with no down time as the other printer modules in the stack  40  take up printing of the pages which would normally be printed by the out of operation printer  10 . 
     Each printer  10  is provided with its document printing requirements over the USB2 communications network (or optional Ethernet) from a work station such as the console  54 . 
     Also, due to memory capacity of each printer  10 , tens of thousands of images and text blocks can be stored in memory allowing completely arbitrary selections on a page by page basis. This allows the printing of matter such as catalogues and magazines which are highly customised for each reader. 
     It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.