Abstract:
An ink supply tube guiding system for a large format inkjet printer includes front and rear oppositely facing tube guide channels each having a lower flange which supports the ink tubes which convey printer ink from stationary reservoirs to printheads mounted on a transversely movable printhead carriage. The tube guide channels provide support for the flexible ink supply tubes which are preferably bundled together in a vertically extending plane which has front and rear reaches of the tubes respectively supported by the front and rear channels and a reversed bend between the front and rear tube ridges which is self-supporting between the guide channels. The tube guide channels and ridges which support the guide channels on the printer frame provide a rigid structure in which the flexible ink tubes may be smoothly guided while minimizing wear of the flexible ink tubes.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS IF ANY 
     None. 
     BACKGROUND OF THE INVENTION AND PRIOR ART 
     The present invention relates to the art of computer driven printers, particularly, large format color ink jet printers. Printers of this type have a printhead carriage which is mounted for reciprocal movement on the printer in a direction orthogonal to the direction of movement of the paper or other medium on which printing is to take place through the printer. The printer carriage of a color printer typically has four removable electric or thermal ink jet pinheads mounted thereon. Each of the printheads contains a supply of ink which, for large scale printers, is generally inadequate due to the large volumes of ink which are required as compared with the ink supply requirements of desk top printers. Consequently, various means have been proposed for continuously or periodically refilling the carriage-borne printheads with ink. These systems fall into two categories. The first comprises offboard or off-axis ink reservoirs which are continuously connected to the carriage-borne or onboard printheads by flexible tubes. The second comprises a “take a gulp” system in which the printhead carriage is periodically moved to one end of its path of travel where it is then connected with off-axis ink reservoirs to fill the onboard printheads. This “take a gulp” system is disclosed in Hewlett-Packard&#39;s Designjet 2000 printer referred to in U.S. patent application Ser. No. 08/805,861 filed Mar. 3, 1997 and published in European Patent Publication No. 0863016 on Sept. 9, 1998. 
     Large format printers are expensive pieces of equipment which preferably should be capable of using different types of ink without significant modification of the printer. The different ink types may for convenience be broadly referred to as indoor ink and outdoor ink, meaning ink intended to be used for production of drawings, posters, and other printed material which may be displayed outdoors or indoors. Outdoor ink is pigment based, i.e. containing a plurality of discrete undissolved pigment particles suspended in a fluid carrier. Dye-based ink has a lower degree of optical density and permanence but is less expensive. Since pigment based inks and dye-based inks are incompatible with each other, a system is desired which enables the use of either type of ink in a printer without crosscontamination of the printer inks by each other. 
     Further, in color printers four separate colors of ink are usually employed composing black and three primary or mid-primary colors such as cyan, magenta and yellow. In color ink printers provision must also be made to ensure that neither incorrect types of ink nor incorrect colors of ink can inadvertently be used in the system. 
     Since the ink delivery tubes connected from offboard reservoirs to onboard printheads continually flex, leakage and breakage of the ink supply tubes is experienced. A reliable ink delivery system and guides for routing the ink delivery tubes to minimize flexing and breakage is desired. 
     SUMMARY OF THE INVENTION 
     The present invention provides an ink supply tube guiding system for a large format printer comprising: 
     a) a front tube guide having a generally vertically extending tube guide surface and a generally horizontally extending tube support surface; 
     b) a rear tube guide having a generally vertically extending tube guide surface and a generally horizontally extending tube support surface, said vertically extending surfaces of said guides being horizontally spaced and generally parallel to define a tube support and guide area therebetween, said tube support surfaces being aligned in a horizontal plane; and 
     c) support structure for supporting said guides on a printer. 
     The present invention further provides a printer having a frame, a transversely moveable printhead carriage mounted for reciprocating movement on said frame, ink supply reservoir means mounted on said frame and an ink supply tube guiding system for delivering ink from said ink reservoir means to said printhead carriage, said guiding system comprising: 
     a) a front tube guide having a generally vertically extending tube guide surface and a generally horizontally extending tube support surface; 
     b) a rear tube guide having a generally vertically extending tube guide surface and a generally horizontally extending tube support surface, said vertically extending surfaces of said guides being horizontally spaced and generally parallel to define a tube support and guide area therebetween, said tube support surfaces being aligned in a horizontal plane; 
     c) support structure supporting said guides on said printer; and 
     d) flexible ink guide tube means in fluid communication with said reservoir means and said printhead carriage, said guide tube means positioned on said support surfaces and confined for sliding movement between said guides and having a reverse bend located between said guides. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a large format printer in which the present invention is useful. 
     FIG. 2 is a top plan view of the printer with its cover removed to show the printhead carriage and ink tube guides and supports. 
     FIG. 3 is a front elevation view of the upper portion of the printer with cover removed to show the printhead carriage and attached printhead connector tubes. 
     FIG. 4 is a vertical cross-section taken at line  4 — 4  on FIG.  3  through the relevant portions of the printer showing the relative position of the carriage, the tube guide system and the ink delivery tubes with a printhead holddown cover on the carriage in its closed position. 
     FIG. 5 is a vertical cross-section taken at line  5 — 5  on FIG.  3  through the relevant portions of the printer showing the relative position of the carriage, the tube guide system and the ink delivery tubes with the printhead holddown cover in its open or raised position. 
     FIG. 6 is a partial front elevation of the rear tube guide and a tube clip partly broken away to show internal construction, fastening the ink tubes to the rear tube guide. 
     FIG. 7 is a partial front elevation view of the rear tube guide with the tube clip and tubes removed. 
     FIG. 8 is a rear elevation view of the tube clip, FIG. 8A being an enlarged cross-section at line  8 A— 8 A of FIG.  8 . 
     FIG. 9 is a right side elevation of a carriage connector and an ink tube support. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows a large format printer  10  of the type which includes a transversely movable printhead carriage enclosed by a plastic or metal hinged cover  12  which extends over a generally horizontally extending platen  14  over which printed media is discharged. At the left side of the platen is a transparent hinged cover  16  which contains four removable ink reservoirs  20 ,  22 ,  24 ,  26  which, through a flexible tube arrangement, supply ink to four inkjet printheads mounted on the moveable carriage. 
     In the plan view of FIG. 2 in which the carriage cover  12  has been removed, it is seen that the printhead carriage  30  is mounted on a pair of transversely extending slider rods or guides  32 ,  34  which in turn are rigidly affixed to the frame of the printer. Also rigidly affixed to the frame of the printer are a pair of tube guide support bridges  40 ,  42  from which front and rear tube guides  44 ,  46  are suspended. The front tube guide  44  has end portions which extend transversely of the printer and an intermediate section  45  which is angled in a horizontal plane near the left bridge support  40  to provide a clearance area for opening a printhead holddown cover  36  on the carriage  30  when the carriage is slid to a position proximate the left side of the platen  14  so that the printhead holddown cover  36  can be easily opened for changing the printheads. 
     A flexible ink delivery tube system conveys ink from the four separate ink reservoirs  20 ,  22 ,  24 ,  26  at the left side of the printer through four flexible ink tubes  50 ,  52 ,  54 ,  56  which extend from an ink reservoirs through the rear and front tube guides  44 ,  46  to the carriage  30  to convey ink to four printheads on the carriage  30 . The ink tube delivery system may be a replaceable system as described and claimed in co-pending application Ser. No. 09/240,039 filed Jan. 29, 1999 (HP 60980039) owned by the assignee of the present invention, the disclosure of which is hereby incorporated herein by reference. 
     At the right side of the printer is a printhead service station  80  at which the printhead carriage  30  may be parked for servicing such as wiping, spitting or priming the printheads. 
     As seen in FIG. 3, each of the four ink reservoirs  20 ,  22 ,  24 ,  26  is easily accessible from the front of the printer when the reservoir cover  16  (seen in FIG. 1) is open so that the reservoirs can be easily removed to be refilled or replaced with new reservoirs. As is known in the art, three of the reservoirs each contain a different base color of ink such as cyan, magenta and yellow and the fourth reservoir contains black ink so that a high number of colors can be produced as desired during printing. 
     As best seen in FIGS. 4 and 5, the front and rear tube guides  44 ,  46  are of channel configuration with each guide  44 ,  46  having a lower flange  60 ,  62  which provides a support surface which extends in a common horizontal plane for supporting the ink delivery tubes  50 ,  52 ,  54 ,  56  along its length with the exception of the reverse bend B (FIG. 2) in the tubes to the right of the printer carriage  30 . The ink tubes are preferably bound together in a flexible wear resistant low friction sheath  58  to confine the tubes in a vertical plane and prevent wear as the tubes move in the guides  44 ,  46 . The tube bundle and sheath is of sufficient rigidity to be self supporting in the region of the reverse bend B. 
     The flexible ink delivery tubes  50 ,  52 ,  54 ,  56  and sheath are all permanently connected to a printhead connector  100  which is a relatively rigid plastic part best seen in FIGS. 4 and 9. The ink delivery tubes are preferably made of a linear low density polyethylene. The protective sheath  58  encloses the flexible ink tubes between their permanent connection to the printhead connector  100  and a rigid plastic tube clip  130  which fastens the ink tubes to the rear tube guide  46  at the location shown in FIG. 2 near the left side of the printer. The protective sheath  58  preferably includes wear resistant lubricious ribs  51 ,  53  on the top of the upper tube  50  and on the bottom of the lower tube  56  and ribs  55  on the sides of all four tubes  50 ,  52 ,  54 ,  56  which face the front and rear tube guides  44 ,  46 . The ribs  51 ,  53 ,  55  are preferably made from polypropylene containing about 5% aramid fibers and 20% polytetrafluoroethuylene (MFLON). The material of the sheath  58  is preferably a polypropylene and EPOM compound which is both flexible and fatigue resistant. The above combination of materials for the sheath and ribs has been found to be considerably more quiet than prior art flexible ink delivery systems. 
     Apertures  70 ,  72  having elongated slots  74 ,  76  in the vertical wall of the rear tube guide  46  receive mating bayonet clips  132 ,  134  on the rear side of the tube clip  130  so that the tube clip may be slid to the right or the left to easily connect or disconnect the clip  130  from the rear tube guide  46 . 
     The lower tube support flange  60  of the front tube guide  44  is shown in a generally horizontal plane in FIG. 4 but a slight downward inclination of the flange toward the opposite flange  62  of the rear tube guide  46  is desirable to assist in smooth movement of the tube bundle in the front guide. Comparison of FIGS. 4 and 5 shows that the lower flange  60  is slightly downwardly inclined in the FIG. 4 view but is somewhat horizontally shorter and is horizontally oriented in the FIG. 5 view. Reduction in the horizontal length of the support flange  60  as seen in FIG. 5 enables the printhead connector  100  and attached tubes to pass to the side of the flange  60  in the region of the left transversely extending section of the front tube guide  44 . Also as seen in FIGS. 2,  4  and  5 , the rear tube guide has an upper flange which extends substantially along the right half of the rear tube guide  46 , the top flange gradually terminating at an angled section centrally located on the printer. It will be appreciated that there is no relative motion between the rear tube guide and the tubes in the section which is uncovered by the top flange. Similarly, the short section of tubes and sheath extending from the permanent connection to the printhead connector  100  to the lower flange  60  of the front tube guide  44  need not be supported by the lower flange  60  since the tubes and sheath are self supporting for short lengths in this area and at the reverse bend B of the tubes. 
     An ink tube clip  130  (FIGS. 6-8) comprises a molded plastic part having four parallel tube channels formed therein. The sheath terminates near the right end of the tube guide  130  and the four ink delivery tubes  50 ,  52 ,  54 ,  56  extend continuously through the channels in the guide  130  to emerge from the left edge of the guide. The guide is provided with foldable upper and lower closure flaps integrally formed with the rear channel-defining wall of the clip  130  and are connected thereto by flexible hinge sections and connectors having inherent resilience so that the doors may be closed over the ink delivery tubes and sheath, the tubes being confined in their respective channels. A resilient hook in the rear wall of the clip  130  engages an aperture in the upper flap to close the flap over the ink delivery tubes. An engagement lip at the lower edge of the rear wall of the clip  130  mates with a complementary hook on the lower edge of the upper flap to securely fasten the flap head hold and hold the tubes in place. A front flap is similarly constructed with a flexible hinge joining it to the channel defining wall of the clip  130 . Complementary hooks on the upper right edge of the channel defining wall of the clip  130  and upper edge of the lower flap securely hold the flap in place to confine the tubes and sheath at the right end of the clip  130 . 
     The rear side of the clip has integrally molded fasteners thereon which are received in complementary shaped slotted apertures in the vertically extending wall of the rear tube guide as shown. 
     Persons skilled in the art will understand that various modifications of the preferred embodiment can be made without departing from the scope of the invention which is defined by the appended claims. For example, the opposed front and rear tube guides  44 ,  46  may be tilted slightly from the positions shown in the drawings such that the generally vertically extending tube guide surfaces and the generally horizontally extending tube support surfaces are not positioned in strictly vertical and horizontal planes.