Abstract:
An apparatus for increasing the waste ink storage capacity of an ink printing device includes a printhead and a drive mechanism. The apparatus includes a spreader mechanism coupled to the drive mechanism of the ink printing device, wherein the spreader mechanism is driven in both horizontal and vertical directions by the drive mechanism to engage waste ink in a waste ink accumulation region and disperse waste ink over said waste ink accumulation region.

Description:
This is a Continuation of application Ser. No. 09/570,607, now U.S. Pat. No. 6,640,448 filed May 12, 2000. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is directed generally to the management of waste ink accumulated in an ink jet printer, and more particularly, to an apparatus and method for increasing the effective capacity for storing waste ink in a maintenance station without increasing the physical capacity of the waste ink collection reservoir. 
     2. Description of the Related Art 
     Maintenance operations are required by ink jet printers to keep the nozzles of the print cartridge operating properly. Typically, such maintenance operations include a combination of wiping the nozzle area of the print cartridge, firing the nozzles at prescribed intervals (spitting), and capping the cartridge during idle periods to prevent the jetted ink which remains on the nozzle plate from evaporating and drying on the nozzle plate, which in turn can clog one or more of the nozzles of the nozzle plate. Typically, the spitting operation occurs at a location in the maintenance station. Thus, the maintenance station includes some sort of reservoir for accumulating waste ink. 
     A variety of attempts have been made to handle and transfer waste ink in an ink jet system. One such attempt is directed to an apparatus having a pump mechanism for carrying waste ink from the pump to a carrying member. Waste ink is supplied to the pump by a series of ink-absorbing materials that, by capillary action, transfer the waste ink to the pump. During operation, a print head wiper slides in contact with a wipe-over portion of an ink-absorbing member carried by an ink-absorbing spring at a predetermined position on the chassis, whereby ink, water droplets, and contaminants adhering to the wiper are imparted to the ink-absorbing member. The ink or water droplets adhering to the ink-absorbing members transfer from one member to another by capillary action, and ultimately to the pump mechanism for carrying waste ink from the pump to a waste ink carrying member. 
     Early ink jet printers used dye-based inks, which were mostly volatile liquids, and the maintenance operations required little capacity for waste ink generated from the spitting operation due to evaporation of the volatile liquid component of the ink and the relatively small quantity of solids in the ink. More recent products, however, have incorporated pigment-based inks that have a larger percentage of solids in them. After the volatile components evaporate, a sludge of mostly solid material is left behind. This solid material builds up in or below the maintenance assembly, and over time, storage capacity must be provided for the solid buildup in order for the maintenance station of the printer to operate properly. To address this increase in capacity, one method would be to increase the size of the waste ink collection reservoir for collecting the waste ink. Such an increase in capacity for collecting waste ink, however, would result in increased size of the printer and/or increased cost relating to the increased capacity for the waste ink collection reservoir. 
     What is needed in the art is a printing system that includes a maintenance station that has the ability to effectively increase the amount of waste ink that can be collected without physically increasing the size of the waste ink collection reservoir. 
     SUMMARY OF THE INVENTION 
     The present invention provides a maintenance unit for use in an ink jet printer having a printer frame and having a waste ink accumulation region. 
     In one form of the invention, the maintenance unit includes a maintenance frame coupled to the printer frame; a maintenance sled moveably coupled to the maintenance frame; and a spreader mechanism slidably coupled to the maintenance frame. The spreader mechanism is driveably coupled to the maintenance sled. The spreader mechanism contacts waste ink to distribute the waste ink over the waste ink accumulation region as the maintenance sled moves relative to the maintenance frame. 
     As one aspect of the invention, the spreader mechanism is controllably moved horizontally with respect to the maintenance frame. 
     As another aspect of the invention, the spreader mechanism is controllably moved both horizontally and vertically with respect to the maintenance frame. 
     An advantage of the present invention is that the amount of waste ink that can be collected without physically increasing the size of the waste ink collection reservoir is increased. 
     Another advantage is that the service life of an ink jet printer into which the present invention is incorporated is increased. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is a partial, perspective view of the frame assembly of an ink jet printer including a maintenance assembly in accordance with the invention; 
     FIG. 2 is a perspective view of the waste ink spreader used in the maintenance assembly of FIG. 1; 
     FIG. 3 is a perspective view of the maintenance assembly of FIG. 1 with the waste ink spreader positioned in the lowered position; 
     FIG. 4 is a reversed perspective view of the maintenance assembly of FIG. 3 with the maintenance sled removed to more clearly show the waste ink spreader positioned in the lowered position; and 
     FIG. 5 is a perspective view of the maintenance assembly of FIG. 1 with the waste ink spreader positioned in the raised position. 
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings and particularly to FIG. 1, there is shown a portion of an ink jet printer  10  that includes a printer frame  12 , a printhead carrier assembly  14 , and a maintenance assembly  16  in accordance with the present invention. Positional terms such as left, right, top, bottom, upper, lower, clockwise or counter-clockwise are assigned based on the orientation of printer  10  in FIG.  1  and should not be considered limiting terminology. 
     Printer frame  12  includes a bottom frame member  18 , two side frame members  20   a ,  20   b , a rear frame member  21 , and a top frame member  22 . Side frame members  20   a ,  20   b  are attached to, and extend generally vertically upwardly from, opposing ends  23   a ,  23   b  of bottom frame member  18 . An upper portion of each of the side frame members  20   a ,  20   b  includes a slot  24  which is adapted to accept a tab  25  of top frame member  22  to mount and position top frame member  22  generally parallel to bottom frame member  18 . Rear frame member  21  is disposed between side frame members  20   a ,  20   b , generally above bottom frame member  18  and below top frame member  22 . An upper surface  26  of bottom frame member  18  includes a waste ink accumulation region  28 . 
     Top frame member  22  includes a horizontally extending guide portion  30  and a vertically upwardly extending guide rail  32  disposed at the rear side of guide portion  30 . Guide rail  32  is adapted to slideably receive printhead carrier assembly  14  and permit reciprocating movement of printhead carrier assembly  14  in relation to guide rail  32  in the directions depicted by arrows  34 . 
     Printhead carrier assembly  14  includes a carriage  35  which holds two print cartridges  36   a ,  36   b , wherein print cartridge  36   a  contains a magenta, yellow and cyan colored pigment based inks and print cartridge  36   b  contains a black dye based ink. In general, pigment based inks contain more solid components than dye based inks. 
     Each of print cartridges  36   a ,  36   b  includes an ink reservoir  38   a ,  38   b  and a printhead  40   a ,  40   b , respectively. Each of printheads  40   a ,  40   b  includes a nozzle plate (not shown) containing a plurality of nozzle openings (not shown) for selectively ejecting ink from the corresponding ink reservoirs  38   a ,  38   b . Although ink reservoirs  38   a ,  38   b  and printheads  40   a ,  40   b , respectively, are shown as forming an integral unit, i.e., print cartridges  36   a ,  36   b , those skilled in the art will recognize that the reservoir may be mounted remotely from the printhead and connected to the printhead via a conduit. In such a configuration, printhead carrier assembly  14  would not need to carry the ink reservoir. 
     The reciprocating movement of printhead carrier assembly  14  along guide rail  32  is effected by a drive means (not shown) of a type known in the art, such as a belt coupled to a stepper motor. The movement of printhead carrier assembly  14  and the ejection of ink by print cartridges  36   a ,  36   b  are controlled by a microprocessor control means, types of which are known in the art. During operation, printhead carrier assembly  14  is moved by the drive means to position printheads  40   a ,  40   b  at various locations within the predetermined limits of permitted travel of printhead carrier assembly  14 . Included in the limited travel of printhead carrier assembly  14  is a printing zone  42 , and a maintenance zone  44  defined by a maintenance start position  46  and a capping region  48 . 
     Printing operations occur in a conventional manner that is well understood in the art. A sheet of print media, such as paper, is carried under printheads  40   a ,  40   b , but above bottom frame member  18 . The sheet is carried by a series of rollers (not shown) in the direction shown by arrow  50 . The sheet typically has a constant separation from printheads  40   a ,  40   b . As the sheet is being carried, printheads  40   a ,  40   b  reciprocally traverse printing zone  42 . Under the control and at locations selected by a microprocessor control means, print cartridges  36   a ,  36   b  selectively eject ink from the respective nozzles of printheads  40   a ,  40   b  onto the sheet. 
     During a maintenance operation, printheads  40   a ,  40   b  are moved into maintenance zone  44  to have a maintenance cycle performed. Two types of maintenance cycles are possible: a printing maintenance cycle and a printhead storage maintenance cycle. Both types of maintenance cycles, i.e., the printing maintenance cycle and the printhead storage maintenance cycle, are effected by maintenance assembly  16 . 
     Maintenance assembly  16  is attached to printer frame  12  above waste ink accumulation region  28  of bottom frame member  18 . Maintenance assembly  16  includes a maintenance frame  52 , a maintenance sled  54  and a waste ink spreader  56 . Preferably, maintenance assembly  16  is located such that a left end  58  of maintenance sled  54  generally defines maintenance start position  46  for printhead carrier assembly  14 . 
     FIG. 2 shows waste ink spreader  56  removed from maintenance sled  54  of maintenance assembly  16 . Waste ink spreader  56  includes a spreader body  66 , an extension member  62 , a pair of guide pins  64   a ,  64   b , and a drive pin  66 . 
     Spreader body  60  is formed as a generally box-shaped structure having a bottom side  68 , a top side  70 , a leading side  72  and a trailing side  74 . Leading side  72  smoothly transitions into bottom side  68  to form a leading curved surface  76 . Also, trailing side  74  smoothly transitions into bottom side  68  to form a trailing curved surface  78 . Referring to FIG. 1, waste ink spreader  56  is positioned in maintenance sled  54  so that trailing side  72  and trailing curved surface  78  face toward the left end  58  of maintenance sled  54 . 
     Extending co-planarly upward from leading side  72  is extension member  62 . Extending co-axially outward from an upper portion of extension member  62  along axis  80  are guide pins  64   a  and  64   b . Extending upwardly from an upper central portion of extension member  62  is drive pin  66 . 
     Waste ink spreader  56  is disposed within the open interior of maintenance frame  52  and within the open interior of maintenance sled  54 . Drive pin  66  is configured to be slidably received by an aperture of maintenance sled  54  such that the lateral (side-to-side) movement of maintenance sled  54  will result in a corresponding horizontal movement of waste ink spreader  56 , while permitting independent vertical movement of waste ink spreader  56 . 
     Referring to FIGS. 3-5, maintenance frame  52  is a generally rectangular structure formed by vertical guide members  82   a ,  82   b ,  82   c , and  82   d . Vertical guide member  82   a  includes two ramped surfaces  84   a ,  84   b  and vertical guide member  82   b  includes two ramped surfaces  84   c ,  84   d . Ramped surfaces  84   a ,  84   b ,  84   c ,  84   d  provide vertical support for maintenance sled  54 . Each of ramped surfaces  84   a ,  84   b ,  84   c ,  84   d  is upwardly inclined towards vertical member  82   c  and each contains three distinct elevations: a printing elevation  86 ; a wiping elevation  88 ; and capping elevation  90 . 
     Vertical guide member  82   a  of maintenance frame  52  further includes a guide surface  92   a  (FIG. 3) and vertical guide member  82   b  of maintenance frame  52  further includes a guide surface  92   b  (FIG.  4 ). Guide surfaces  92   a ,  92   b  provide vertical support for guide pins  64   a ,  64   b , respectively, of waste ink spreader  56 . Each of guide surfaces  92   a ,  92   b  has a lower horizontal elevation  94  and an inclined elevation  96 . Thus, as can be most clearly seen in FIG. 4, guide pins  64   a ,  64   b  of waste ink spreader  56  are slidably carried by the vertical support provided by guide surfaces  92   a ,  92   b , respectively, along the extent of lower horizontal elevation  94  and inclined elevation  96 . 
     Maintenance frame  52  further includes a print latch  98  pivotally coupled at the intersection of vertical guide members  82   b ,  82   d . Print latch  98  contains a stop surface  98   a  and a spring (not shown). Print latch  98  functions to actively control the placement of maintenance sled  54  along ramped surfaces  84   a ,  84   b ,  84   c ,  84   d . When print latch  98  is in the open position, sled  54  is allowed to travel along ramped surfaces  84   a ,  84   b ,  84   c ,  84   d  to printing elevation  86 . When print latch  98  is in the closed position, sled  54  is prohibited from traveling along ramped surfaces  84   a ,  84   b ,  84   c ,  84   d  to printing elevation  86 . The spring biases print latch  98  towards the closed position. The structure and operation of print latch  98  is well known in the art. 
     Maintenance sled  54  is disposed within the open interior of maintenance frame  52 . Maintenance sled  54  has four generally vertical members  100   a ,  100   b ,  100   c  and  100   d  that form a rectangular structure. Maintenance sled  54  further includes a bottom horizontal member  102 , and four dowel members  104   a ,  104   b ,  104   c  and  104   d . Dowel members  104   a ,  104   b  extend horizontally, outward from vertical member  100   a  and dowel members  104   c ,  104   d  extend horizontally, outward from vertical member  100   b . Dowel members  104   a ,  104   b ,  104   c ,  104   d  are supported by the corresponding ramped surfaces  84   a ,  84   b ,  84   c ,  84   d  on maintenance frame  52  and are guided along ramped surfaces  84   a ,  84   b ,  84   c ,  84   d  to raise or lower maintenance sled  54  relative to maintenance frame  52 . 
     Maintenance sled  54  includes wiper assemblies  106   a ,  106   b ; discharge regions  108   a ,  108   b ; and cap assemblies  110   a ,  110   b . Each wiper assembly  106   a ,  106   b  is attached to bottom member  102  of maintenance sled  54  and includes a wiper  112   a ,  112   b , respectively, made of an elastomeric material such as Texin 480-A (Mites, Inc.). Wiper assemblies  106   a ,  106   b  remove excess ink from the exterior of the nozzles on printheads  40   a ,  40   b , respectively. 
     Discharge regions  108   a ,  108   b , are located to the right of wiper assemblies  106   a ,  106   b , respectively. Discharge region  108   a  forms a cavity defined by the combination of a vertical member  114  and vertical side members  100   a ,  100   b  of maintenance sled  54 . As shown, discharge region  108   b  includes a rotary drum having an ink collection surface that is cleaned by a scraper that contacts the ink collection surface of the rotary drum. However, alternatively, the rotary drum could be removed to form a discharge cavity though which purged ink expelled by printhead  40   b  would pass. 
     Cap assemblies  110   a ,  110   b  are positioned to the right of discharge regions  108   a ,  108   b . Cap assemblies  110   a ,  110   b  include printhead caps  116   a ,  116   b.    
     Maintenance sled  54  further includes a capping tab  118  that extends vertically upward from vertical member  100   c . Capping tab  118  facilitates the movement of sled  54  to wiping elevation  88  or to capping elevation  90  of ramped surfaces  84   a ,  84   b ,  84   c ,  84   d  when contacted by print cartridge  36   a.    
     As maintenance sled  54  moves from left to right, waste ink spreader  56  moves from left to right, thereby spreading the accumulated ink generally to the right as the accumulated ink contacts leading curved surface  76  of spreader body  60 . A right to left movement of maintenance sled  54  causes waste ink spreader  56  to spread the accumulated ink generally to the left as the accumulated ink contacts trailing curved surface  78  spreader body  60 . 
     The operation of the waste ink spreader  56  will now be discussed in relation to the maintenance cycles, i.e., the printing maintenance cycle and printhead storage maintenance cycle, and will be discussed with reference to FIGS. 1-5. 
     In a printing maintenance cycle, printhead carrier assembly  14  moves to the right along guide rail  32  (FIG. 1) to maintenance region  44 . Printhead carrier assembly  14  passes maintenance start position  46  and as printhead carrier assembly  14  moves farther to the right, the rightward leading print cartridge  36   a  contacts capping tab  118  (FIG. 3) of maintenance sled  54 . This contact causes maintenance sled  54  to move to the right with the printhead carrier assembly  14 . The rightward movement causes print latch  98  to momentarily reside in the open position thereby releasing sled  54  from printing elevation  86 . The rightward movement raises maintenance sled  54  to wiping elevation  88  because dowel members  104   a ,  104   b ,  104   c ,  104   d  of maintenance sled  54  are guided along ramped surfaces  84   a ,  84   b ,  84   c ,  84   d . In addition, the rightward movement of maintenance sled  54  causes waste ink spreader  56  to move rightward in conjunction with the generally lateral movement of maintenance sled  54  in a generally horizontal path because guide pins  64   a ,  64   b  are guided by the lower horizontal elevation  94  of guide surfaces  92   a ,  92   b . During the rightward movement of waste ink spreader  56 , leading curved surface  76  engages and disperses, or spreads, the accumulated ejected ink in waste ink accumulation region  28 . 
     Once sled  54  reaches wiping elevation  88 , print latch  98  resumes the closed position thereby impeding sled  54  from traveling back down ramped surfaces  84   a ,  84   b ,  84   c ,  84   d  to printing elevation  86  due to stop surface  98   a  on print latch  98 . Although sled  54  has been raised to the wiping elevation due to the influence of ramped surfaces  84   a ,  84   b ,  84   c ,  84   d , waste ink spreader  56  is not raised and travels on a generally horizontal path due to the influence of lower horizontal elevation  94  of guide surfaces  92   a ,  92   b . After print latch  67  resumes the closed position, printhead carrier assembly  14  begins to travel back to the left towards printing zone  42 . As print cartridges  36   a ,  36   b  pass over discharge regions  108   a ,  108   b , respectively, ink is ejected from the nozzles in printheads  40   a ,  40   b . The ejected ink falls through discharge regions  108   a ,  108   b  and accumulates in waste ink accumulation region  28 . As printhead carrier assembly  14  moves father to the left, the nozzles of printheads  40   a ,  40   b  are wiped by wipers  112   a ,  112   b  to remove excess ink from the nozzles and a portion of the leftward leading print cartridge  36   b  contacts print latch  98  causing print latch  98  to assume the open position. Once print latch  98  is in the open position, dowel members  104   a ,  104   b ,  104   c ,  104   d  of maintenance sled  54  migrate down ramped surfaces  84   a ,  84   b ,  84   c ,  84   d  from wiping elevation  88  to printing elevation  86  due to gravity. After printhead carrier assembly  14  has completely entered printing zone  42 , print latch  98  resumes the closed position due to the spring bias of print latch  98 . 
     During the leftward movement of maintenance sled  54 , waste ink spreader  56  is caused to move leftward in conjunction with the generally lateral movement of maintenance sled  54  in a generally horizontal path because guide pins  64   a ,  64   b  are guided by the lower horizontal elevation  94  of guide surfaces  92   a ,  92   b . During the leftward movement of waste ink spreader  56 , trailing curved surface  78  of waste ink spreader  56  further engages and disperses the accumulated ejected ink in waste ink accumulation region  28 . 
     The printhead storage maintenance cycle is generally analogous to the printing maintenance cycle, except that printhead carrier assembly  14  does not stop its rightward motion when maintenance sled  54  is at wiping elevation  88 . Instead, as shown in FIG. 5, printhead carrier assembly  14  continues to move to the right, thereby further moving maintenance sled  54  to the right until dowels  104   a ,  104   b ,  104   c ,  104   d  of sled  54  are at capping elevation  90  of ramp surfaces  84   a ,  84   b ,  84   c ,  84   d . When maintenance sled  54  is at capping elevation  90  (defined as being in capping region  48 ), caps  116   a ,  116   b , respectively form an air seal around the nozzles on printheads  40   a ,  40   b  to prevent the ink on the nozzles from drying. Printhead carrier assembly  14  can stay at capping region  48  for an indefinite amount of time. 
     The rightward movement of maintenance sled  54  during the printhead maintenance cycle causes waste ink spreader  56  to move rightward in conjunction with the generally lateral movement of maintenance sled  54 , first in a generally horizontal path because guide pins  64   a ,  64   b  are guided by the lower horizontal elevation  94  of guide surfaces  92   a ,  92   b , and then on a generally inclined path as guide pins  64   a ,  64   b  are guided by inclined elevation  96  of guide surfaces  92   a ,  92   b . Thus, during the rightward movement of waste ink spreader  56 , leading curved surface  76  engages and disperses the accumulated ejected ink in waste ink accumulation region  28 . However, at the later extent of this lateral travel waste ink spreader  56  also moves vertically due to the incline of inclined elevation  96  to thereby ramp upwardly the waste ink being spread. By including this vertical movement of waste ink spreader  56 , the waste ink storage capacity of maintenance assembly  16  is increased by about 25 percent over that if only horizontal movement along lower horizontal elevation  94  was used. 
     Once printhead carrier assembly  14  begins to move to the left toward printing zone  42 , maintenance sled  54  migrates down ramp surfaces  84   a ,  84   b ,  84   c - 84   d  from capping elevation  90  to wiping elevation  88  thereby disengaging caps  116   a ,  116   b  from the respective printheads  40   a ,  40   b . As stated earlier printheads  40   a ,  40   b  eject, or spit, ink from the nozzles through discharge regions  108   a ,  108   b  and are wiped by wipers  112   a ,  112   b  as printhead carrier assembly  14  moves to the left. Maintenance sled  54  stays at wiping elevation  88  until the leftward leading print cartridge  36   b  on printhead carrier assembly  14  engages print latch  98 . 
     During the leftward movement of maintenance sled  54 , waste ink spreader  56  moves leftward in conjunction with the generally lateral movement of maintenance sled  54 . During the leftward of waste ink spreader  56 , trailing curved surface  78  of waste ink spreader  56  further engages and disperses the accumulated ejected ink in waste ink accumulation region  28  as waste ink spreader  56  returns to horizontal elevation  94 . 
     As shown in FIGS. 1-5 and described above, a single waste ink spreader  56  engages the ink ejected from print cartridge  36   a  and accumulated in waste ink accumulation region  28 . However, one skilled in the art will recognize that the present invention can be adapted to accommodate ink jet printer systems having multiple pigment based ink cartridges. Where multiple pigment based ink cartridges are used, each ink spreading surface engages ink ejected through a different discharge cavity. Furthermore, a separate dedicated spreader mechanism can be provided for each print cartridge. It is also within the scope of the present invention to incorporate the spreader mechanism as an integral component of the maintenance sled. 
     By spreading the accumulated ink over a larger surface area of waste ink accumulation region  28 , the waste ink storage capacity of printer  10  is increased without increasing the size of the printer or increasing the size of the waste ink reservoir. In addition, by preventing the accumulation of waste ink at levels which would impede the operation of the maintenance sled, the life of the maintenance assembly, and in turn the life of the printer, is increased. 
     While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within know or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.