Abstract:
An apparatus and method of driving multiple printer functions using the same motor is provided. The method includes providing a motor; providing a selector pin; providing a cam member assembly including a cam member including a plurality of paths, each path corresponding to a printer function; and relatively moving the cam member and the selector pin through the plurality of paths to selectively permit the motor to drive the corresponding printer function.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates generally to the field of inkjet printers, and in particular to a mechanical device that enables selective engagement of one or more of a plurality of operational modes of the printer, where each mode is driven by the same motor. 
       BACKGROUND OF THE INVENTION 
       [0002]    An inkjet printing system typically includes one or more printheads and their corresponding ink supplies. Each printhead includes an ink inlet that is connected to its ink supply and an array of drop ejectors, each ejector consisting of an ink chamber, an ejecting actuator and an orifice through which droplets of ink are ejected. The ejecting actuator may be one of various types, including a heater that vaporizes some of the ink in the chamber in order to propel a droplet out of the orifice, or a piezoelectric device which changes the wall geometry of the chamber in order to generate a pressure wave that ejects a droplet. The droplets are typically directed toward paper or other print medium (sometimes generically referred to as paper herein) in order to produce an image according to image data that is converted into electronic firing pulses for the drop ejectors as the print medium is moved relative to the printhead. 
         [0003]    Motion of the print medium relative to the printhead may consist of keeping the printhead stationary and advancing the print medium past the printhead while the drops are ejected. This architecture is appropriate if the nozzle array on the printhead can address the entire region of interest across the width of the print medium. Such printheads are sometimes called pagewidth printheads. A second type of printer architecture is the carriage printer, where the printhead nozzle array is somewhat smaller than the extent of the region of interest for printing on the print medium and the printhead is mounted on a carriage. In a carriage printer, the print medium is advanced a given distance along a print medium advance direction and then stopped. While the print medium is stopped, the printhead carriage is moved in a direction that is substantially perpendicular to the print medium advance direction as the drops are ejected from the nozzles. After the carriage has printed a swath of the image while traversing the print medium, the print medium is advanced, the carriage direction of motion is reversed, and the image is formed swath by swath. In order to accomplish the motions necessary for printing in a carriage printer, there are typically at least two motors—the motor for print medium advance, and the motor for carriage motion. The examples described in the present invention relate to a carriage printer architecture. 
         [0004]    As carriage printer technology matures, there is a need to offer more functions and at lower cost. While previous printers may have dedicated a separate motor (in addition to the motor for paper advance and the motor for carriage motion) to drive an additional function, offering the function without the need for an additional motor is desirable. 
         [0005]    It is known in the prior art to use the power of the paper advance motor to operate the various functions of the maintenance station in an inkjet printer. U.S. Pat. Nos. 6,846,060 and 7,225,697, for example, describe power transmission mechanisms that are selectively engaged or disengaged depending on whether or not the carriage is parked at the maintenance station. If the carriage is parked at the maintenance station, a feature on the carriage enables the power transmission mechanism to be engaged. By this means, the maintenance station functions including wiping and capping may be powered by the paper advance motor. When the carriage moves away from the maintenance station, the feature on the carriage no longer enables the power transmission to be engaged for maintenance operations, so that the paper advance motor is used for moving paper through the printer. 
         [0006]    For some modes of printing, it is necessary to operate different paper advancing rollers at different times or in different directions. In such a case, a mechanism such as those in &#39;060 and &#39;697 which only allows engagement when the carriage and printhead are parked at the maintenance station is not sufficient. 
         [0007]    There is a need, therefore, for a selector mechanism that can operate in different selection positions even after the carriage has moved away, and that can selectively engage one or more of a plurality of functions, driven selectively by a single motor. 
       SUMMARY OF THE INVENTION 
       [0008]    According to one feature of the present invention, a printer includes a selector pin and a cam member. The cam member includes a plurality of paths with each path corresponding to a printer function. The cam member and the selector pin are configured to provide relative movement of the selector pin through the plurality of paths with the location of the selector pin in one of the plurality of paths enabling the corresponding printer function. 
         [0009]    According to another feature of the present invention, a method of driving multiple printer functions using the same motor includes providing a motor; providing a selector pin; providing a cam member assembly including a cam member including a plurality of paths, each path corresponding to a printer function; and relatively moving the cam member and the selector pin through the plurality of paths to selectively permit the motor to drive the corresponding printer function. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    In the detailed description of the preferred embodiments of the invention presented below, reference is made to the accompanying drawings, in which: 
           [0011]      FIG. 1  is a perspective illustration of a printer including an embodiment of the present invention; 
           [0012]      FIG. 2  is a schematic side view showing paper being advanced through the printer; 
           [0013]      FIG. 3  is a top view of an embodiment of the selector assembly of the present invention; 
           [0014]      FIG. 4  is a perspective view of an embodiment of the selector assembly of the present invention; 
           [0015]      FIG. 5  is a schematic side view showing paper being advanced in a deskew mode; 
           [0016]      FIG. 6  is a schematic side view showing a photo paper tray in its forward position; 
           [0017]      FIG. 7  is a schematic side view showing a photo paper tray in its printing position; and 
           [0018]      FIG. 8  is a perspective view of a second embodiment of the cam member assembly. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    The present description will be directed in particular to elements forming part of, or cooperating more directly with, apparatus in accordance with the present invention. It is to be understood that elements not specifically shown or described may take various forms well known to those skilled in the art. 
         [0020]    In the following description of preferred embodiments, directional terminology such as front, rear, left, right, top, bottom, etc. is used with reference to the orientation of the figure being described or to the orientation of a component when it is located in its normal operating position in the example being described. Because components of the 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. 
         [0021]      FIG. 1  shows a portion of a carriage printer that includes an embodiment of the present invention. Printer chassis  300  has a print region  303  across which carriage  200  is moved back and forth between the right side  306  and the left side  307  of printer chassis  300  while printing. Carriage motor  380  moves belt  384  to move carriage  200  back and forth along carriage guide rail  382 . Printhead chassis  250  is mounted in carriage  200 , and ink supplies  262  and  264  are mounted in the printhead chassis  250 . Paper, or other print media is loaded along paper load entry direction  302  toward the front  308  of printer chassis  300 . A variety of rollers are used to advance the medium through the printer, as shown schematically in the side view of  FIG. 2 . 
         [0022]    In  FIG. 2 , a pickup roller  320  moves the top sheet  371  of a stack  370  of paper or other media in the direction of arrow  302 . A turn roller  322  toward the rear  309  of the printer chassis  300  acts to move the paper around a C-shaped path (in cooperation with a curved rear wall surface) so that the paper continues to advance along direction arrow  304  from the rear  309  of the printer. The paper is then moved by feed roller  312  and idler roller(s)  323  to advance across print region  303 , and from there to a discharge roller  324  and star wheel(s)  325  so that printed paper exits along direction  304 . Feed roller  312  includes a feed roller shaft  319  along its axis, and feed roller gear  311  is mounted on the feed roller shaft  319 . Feed roller  312  may consist of a separate roller mounted on feed roller shaft  319 , or may consist of a thin high friction coating on feed roller shaft  319 . 
         [0023]    Referring back to  FIG. 1 , selector assembly  100  is mounted in association with feed roller shaft  319 , and is near feed roller gear  311 . The motor  394  that powers the paper advance rollers is shown schematically in  FIG. 1 . Hole  310  at the right side  306  of the printer chassis  300  is where the motor gear (not shown) protrudes through in order to engage feed roller gear  311 , as well as the gear for the discharge roller (not shown). For normal paper pick-up and feeding, it is desired that all rollers rotate in forward direction  313 . Toward the left side  307  in the example of  FIG. 1  (and near the end of the feed roller  312  that is opposite the end where feed roller gear  311  is mounted) is the maintenance station  330 . Toward the rear  309  of the printer in this example is located the electronics board  390 , which contains cable connectors  392  for communicating via cables (not shown) to the printhead carriage  200  and from there to the printhead. Also on the electronics board are typically mounted motor controllers for the carriage motor  380  and for the paper advance motor, a processor and/or other control electronics for controlling the printing process, and an optional connector for a cable to a host computer. 
         [0024]      FIG. 3  shows a top view and  FIG. 4  shows a perspective view of a first embodiment of the selector assembly  100  of this invention. Selector assembly  100  includes a cam member assembly  110 , a spring  130  and a selector pin assembly  140  that are each coaxially mounted on the feed roller shaft  319  in this embodiment. Cam member assembly  110  includes a cam member  111  which includes a first cam path  112 , a second cam path  113 , a third cam path  114  (cam paths indicated as dotted lines in  FIG. 3 ), and a stop position  115 ; a sleeve  116 ; a pushing feature  117 ; and a flange  118 . Cam member assembly  110  can optionally be made as an integrally formed part, for example by injection molding. One end of each cam path is the stop position  115 , while the other end of the three cam paths are slots  122 ,  123  and  124  respectively. Spring  130  is positioned toward the end of the feed roller shaft  319  and is adjacent to flange  118  of cam member assembly  110 . Optionally the flange  118  may have an internal recess inside of which one end of spring  130  is retained. The other end of spring  130  is positioned against a wall at the right side  306  of printer chassis  300 . 
         [0025]    On the other side of cam assembly  110 , the selector pin assembly  140  is mounted. Selector pin assembly  140 , which optionally may be made as an integrally formed part (for example, by injection molding), includes selector pin  142  extending radially outwardly from friction mount sleeve  144 , and arm(s)  146  also extending outwardly from friction mount sleeve  144 . Cam member  111  cantilevers over friction mount sleeve  144 , such that selector pin  142  is captured within the open area of cam member  111 , and extends through it, as seen more clearly in  FIG. 4 . Selector pin  142  is sized to fit into each of slots  122 ,  123  and  124 , as well as into stop position  115 . 
         [0026]    Also shown in  FIG. 4  are slots  148  in friction mount sleeve  144 , which functions as a type of clutch mechanism. The fit of friction mount sleeve  144  on feed roller shaft  319  is sufficiently close that friction mount sleeve  144  will rotate when feed roller shaft  319  rotates, but it is loose enough that friction mount  144  can be rotated independently of feed roller shaft  319 . The fit of sleeve  116  of cam assembly  110  is loose enough, or cam assembly  110  is optionally constrained rotationally, so that cam assembly  110  does not rotate significantly when feed roller shaft  319  rotates. Friction mount sleeve  144  is constrained translationally along feed roller shaft  319 , so that it may not be moved back and forth significantly along the shaft. Cam assembly  110  is free to move back and forth along feed roller shaft  319 , but is biased toward selector pin assembly  140  by spring  130 . 
         [0027]    Next the operation of the selector assembly  110  will be explained. Spring  130  tends to push cam assembly  110  toward selector pin assembly  140 , so that selector pin  142  is normally located in one of the three slots  122 ,  123  or  124 . However, if carriage  200  is moved sufficiently toward the right side  306  of printer chassis  300  in this example, a feature (not shown) on carriage  200  hits pushing feature  117 , causing cam assembly  110  to move toward the right and compress spring  130 . As this happens, the selector pin  142  will move relative to the cam member  111  along the cam path  112 ,  113  or  114  to stop position  115  from the slot ( 122 ,  123  or  124  respectively) that it had been in. If the pin had been in slot middle slot  122 , no rotation of selector pin assembly  140  occurs during this operation. However, if the pin had been in either slot  123  or  124 , the interaction of pin  142  and the outside cam surfaces of cam member  111  will cause selector pin assembly  140  (including arm  146 ) to rotate relative to the feed roller shaft  319 . If the carriage  200  is moved to the left in this example, spring  130  pushes cam assembly  110  toward selector pin assembly  140  so that selector pin  142  moves along one of the cam paths  112 ,  113  or  114 , the particular path depending upon whether the feed roller  312  is rotated as carriage  200  moves to the left. If feed roller  312  is not rotated, then selector pin  142  moves parallel to the axis of the feed roller shaft  319  along path  112  into slot  122 . If the media advance motor turns feed roller  312  in forward rotation direction  313 , friction mount sleeve  144  will cause selector pin assembly  140  to rotate in direction  313 , while cam assembly  110  does not rotate, so that selector pin  142  moves along cam path  114  to slot  124 . If the media advance motor turns feed roller  312  in reverse, friction mount sleeve  144  will cause selector pin assembly  140  to rotate in reverse, while cam assembly  110  does not rotate, so that selector pin  142  moves along cam path  113  to slot  123 . Selector pin  142  is held in whichever slot it was moved to until carriage  200  is moved back at some later time and pushes the pushing feature  117  so that the selector pin is moved to its location at the stop position  115 , and can then be moved to a different slot if desired. Different slots may be reached from the intermediate location by the selector pin  142  following different cam paths. While in the present example, the intermediate location is defined by stop position  115  beyond which selector pin  142  can not move, in other embodiments the intermediate location does not need to occur at a stop position. 
         [0028]    As selector pin assembly  140  is rotated and held in different positions corresponding to slots  122 ,  123  or  124 , arm  146  rotates correspondingly. There are a variety of possible gear engagement/disengagement possibilities that the selector pin assembly  100  of the present invention may enable. In one embodiment of this invention, arm  146  is configured to interact with different gears or gear assemblies, selectively enabling or disabling power transmission from the media feed motor, depending upon its rotational position around feed roller shaft  319 . For example, in one rotational position, a surface of arm  146  may prevent a pivoting gear assembly from rotating into engagement with another gear assembly, while in another rotational position of arm  146 , that pivoting gear assembly is free to rotate into engagement with a first gear or a second gear, depending upon the direction of rotation of feed roller shaft  319 . In another embodiment, in one rotational position an arm may push a gear out of engagement with another gear, while in another rotational position, an arm  146  (the same arm, or a different arm, or a different surface of the same arm) may push a gear into engagement with another gear, regardless of direction of rotation of the feed roller shaft. In still another embodiment, a gear that is driven by the media advance motor may be mounted on arm  146  and rotated into or out of engagement with other gears. 
         [0029]    Once the carriage  200  has enabled the changing of power transmission engagement in this invention, the carriage is free to move away from the selector assembly  100 . This means that different operational modes of printing can be selectively enabled by selector assembly  100  of the present invention. Furthermore, in this embodiment, three separate power transmission engagements are possible (corresponding to selector pin being in either slot  122 ,  123  or  124 ), rather than just two. In other embodiments there can be even more individually selectable power transmission engagements, by designing a cam member  111  having more than three branches of cam paths. In fact, it is also possible to have a translational motion of the selector pin assembly  140  along feed roller shaft  319 , so that arm  146  enables a different gear engagement when selector pin  142  is in the stop position  115  than when the selector pin is in slot  122 . In such an embodiment, four different power transmission engagements could be enabled by the selector assembly  100  shown in  FIGS. 3 and 4 . 
         [0030]    A variety of printer functions may be selectively enabled using selector assembly  100 . In one embodiment of this invention, a pick function is enabled with selector pin  142  in slot  124 , a printing function is enabled with selector pin  142  in slot  122 , and a photo tray movement function is enabled with selector pin  142  in slot  123 . In the pick function forward mode, power from the media advance motor is transmitted to all four of the rollers shown schematically in  FIG. 2 , i.e. pick roller  320 , turn roller  322 , feed roller  312 , and discharge roller  324  and causes them to rotate in forward direction  313 . Thus, the pick roller  320  advances the top sheet  371  to the turn roller  322 , the turn roller  322  advances the sheet to the feed roller  312 , and the feed roller advances the sheet to the discharge roller  324  when the motor rotates such that the four rollers rotate in forward direction  313 . 
         [0031]    The pick function has a second mode called the deskew mode, which is enabled with selector pin  142  in slot  122 , but with the media advance motor rotating in reverse. The deskew mode may be useful for certain types of jobs, such as printing photos on 4″×6″ photo papers. The roller motion in deskew mode is indicated in  FIG. 5 . With reference to  FIG. 1 , the gear from the media advance motor that extends through hole  310  is always engaged with feed roller gear  311  and the discharge roller gear (not shown). Thus when the motor rotates in reverse, both the feed roller  312  and the discharge roller  324  rotate in reverse direction (opposite  313 ). However, in an embodiment of this invention, the pick roller  320  and the turn roller  322  are each connected to power transmission through pivoting gear assemblies, such that even if the motor turns in reverse, the pick roller  320  and the turn roller  322  continue to move in forward direction  313 . Thus, in the deskew mode, the pick roller  320  and the turn roller  322  advance the paper toward the feed roller  312 , but the feed roller  312  is rotating in reverse and resists forward movement of the paper. If the paper is misoriented such that its leading edge is not parallel with the feed roller  312 , the first portion of the leading edge that hits reversely spinning feed roller  312  is slowed down until the rest of the leading edge can catch up, thus deskewing the paper. When deskewing is completed, the carriage  200  is again moved to the right such that the pushing feature  117  is pushed and the selector pin  142  moves to the stop position  115 . With the feed roller  312  stationary, the carriage  200  moves to the left, such that the selector pin moves to slot  122  to enable the printing function mode. 
         [0032]    In the printing function mode, power from the media advance motor is transmitted to forwardly rotate the turn roller  322 , the feed roller  312  and the discharge roller  324 , but no power is transmitted to the pick roller  320 . Thus in the printing mode, with the pick roller  320  disabled, printing media can continue to advance through the printer without the pick roller  320  advancing a next sheet until needed. If the deskew mode of paper advance is being used, then the next sheet cannot be advanced to feed roller  312  until the previous sheet has been discharged, because the deskew mode operates the feed roller  312  and the discharge roller  324  in reverse. 
         [0033]    However, in the pick function forward mode (also called the “tailgating mode”) described above, one sheet can immediately follow the next, with no gap between the two sheets. Thus when deskew is not required, the faster printing throughput tailgating mode is used. The tailgating mode begins with the selector pin moved into slot  123  and the paper advance motor rotating all four rollers in the forward direction  313 . Once the paper has been advanced to the turn roller  322 , the carriage  200  can be moved to the right, pushing the cam assembly  110 , thus moving the selector pin  142  to stop position  115 . During carriage motion (e.g. during printing of a swath) the feed roller  312  is stopped. If the feed roller  312  remains stopped as the carriage moves back to the left, selector pin  142  will be released back to slot  122  into the printing position. When it is desired to pick the next sheet, the carriage  200  moves to the right, pushing the cam assembly  110  and releasing it while the feed roller  312  moves forward, so that selector pin  142  moves into slot  124  to enable the pick forward mode for picking the next sheet. Since in this tailgating sequence it is never required to move the feed roller  312  backwards, it is evident that the picking operation can be activated or deactivated at any point during printing. Thus a sheet can be picked immediately after the previous one, with no gaps between the two sheets. The timing of switching modes by actuating selector assembly  100  can be adjusted depending upon the length of the sheets of media. 
         [0034]    A third function which can be optionally selected is photo tray movement, for example when selector pin  142  is positioned in slot  123 . In one embodiment, in this position an arm  146  of selector pin assembly  140  causes a gear to engage with a rack (not shown) that can move a photo paper tray back and forth depending on the direction of motor rotation, as in  FIGS. 6 and 7 . In both figures there is a paper stack  370  in main paper tray  372  and there is a stack of photo paper  373  in photo paper tray  374 . The sheets in paper stack  370  are of a larger size (for example, 8.5″×11″) compared to the sheets in paper stack  373  (for example, 4″×6″), and photo paper tray  374  is not as long as main paper tray  372 . In  FIG. 6 , the photo paper tray  374  has been moved to its forward position, for example by rotating the paper advance motor in a first direction such that the gear and the rack cause the tray to move forward. In this position, the pick roller  320  is able to contact the top sheet in paper stack  370  in the main tray  372 . Also in the forward position of the photo paper tray  374 , additional photo paper  373  may be loaded. In  FIG. 7 , the photo tray  374  has been moved along direction  302  to its printing position, for example by rotating the paper advance motor in a second direction that is opposite the first direction. In the printing position of the photo paper tray  374 , the pickup roller  320  is able to contact the top sheet in photo paper stack  373 . In some embodiments the pickup roller is mounted on a pivotable pick arm which is able to be moved up or down to rest on the top sheet of whichever tray is beneath it. 
         [0035]    While the embodiments above described a particular group of functions that may be enabled by selector assembly  100 , various other functions may be enabled in other embodiments. These may include other functions that require motion, such as the maintenance functions of capping, wiping or pumping. 
         [0036]    Selector assembly  100  may be made in other ways than the coaxially mounted cam assembly  110 , spring  130  and selector pin assembly  140 . A second embodiment of a selector assembly is shown in  FIG. 8 . In this second embodiment, the functions of the cam assembly  110  and the spring  130  are incorporated together as leaf spring cam assembly  150 . Leaf spring cam assembly  150  consists of bent thin strip of metal or plastic, for example, and includes a cam member portion  151  with slots  152 ,  153  and  154  and a stop position  155 ; a pushing portion  157 ; and a mounting portion  158  with a hole  159 . Leaf spring cam assembly  150  may be made by standard metal or plastic forming processes. Leaf spring cam assembly  150  operates in much the same way as was described above for the cam assembly  110 , and cam member portion  151  has cam paths similar to those in cam member  111 . A selector pin assembly  140  of the same or similar design to that described above operates in conjunction with leaf spring cam assembly  150 . Feed roller shaft  319  passes through hole  159  in mounting portion  158 . Cam member portion  151  cantilevers over selector pin assembly  140  such that selector pin  142  is captured within the open slotted region. The mounting portion  158  is constrained translationally on feed roller shaft  319 , so that in its normal position, cam member portion  151  is located such that selector pin  142  will be positioned in one of the slots  152 ,  153  or  154 . In order to release the pin from one of the slots, the carriage  200  pushes the pushing portion  157 , causing the leaf spring cam assembly to bend, and allowing the cam member portion  151  to move parallel to the axis of the feed roller shaft  319  in a direction that locates the stop position  155  at the selector pin  142 . When the carriage  200  moves away, the restoring force of the leaf spring cam assembly  150  causes it to assume its normal configuration, and selector pin  142  will be located in slot  152 ,  153  or  154 , depending on whether and which way the feed roller  312  turned as the carriage  200  released the pushing portion  157 . 
         [0037]    The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the scope of the invention. 
       PARTS LIST 
       [0000]    
       
           100  Selector assembly 
           110  Cam member assembly 
           111  Cam member 
           112  First cam path 
           113  Second cam path 
           114  Third cam path 
           115  Stop position 
           116  Sleeve 
           117  Pushing feature 
           118  Flange 
           122  First slot 
           123  Second slot 
           124  Third slot 
           130  Spring 
           140  Selector pin assembly 
           142  Selector pin 
           144  Friction mount sleeve 
           146  Arm 
           148  Friction mount slots 
           150  Leaf spring cam assembly 
           151  Cam member portion 
           152  First slot 
           153  Second slot 
           154  Third slot 
           155  Stop position 
           157  Pushing portion 
           158  Mounting portion 
           159  Hole 
           200  Carriage 
           250  Printhead chassis 
           262  Multichamber ink supply 
           264  Single chamber ink supply 
           300  Printer chassis 
           302  Paper load entry 
           303  Print region 
           304  Paper exit 
           306  Right side of printer chassis 
           307  Left side of printer chassis 
           308  Front of printer chassis 
           309  Rear of printer chassis 
           310  Hole for paper advance motor drive gear 
           311  Feed roller gear 
           312  Feed roller 
           313  Forward rotation of feed roller 
           319  Feed roller shaft 
           320  Pickup roller 
           322  Turn roller 
           323  Idler roller 
           324  Discharge roller 
           325  Star wheel 
           330  Maintenance station 
           370  Stack of media 
           371  Top sheet 
           372  Main paper tray 
           373  Photo paper stack 
           374  Photo paper tray 
           380  Carriage motor 
           382  Carriage rail 
           384  Belt 
           390  Printer electronics board 
           392  Cable connectors