Patent Publication Number: US-7712986-B2

Title: Printhead carrier for an imaging apparatus

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
   None. 
   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   None. 
   REFERENCE TO SEQUENTIAL LISTING, ETC. 
   None. 
   BACKGROUND 
   1. Field of the Invention 
   The present invention relates generally to an imaging apparatus, and more particularly to those having or using a printhead carrier. 
   2. Description of the Related Art 
   In the prior art, an imaging apparatus, such as an ink jet printer, forms an image on a print medium, such as paper, by applying ink to the print medium. Such an ink jet printer includes a reciprocating printhead carrier that transports one or more ink jet printhead cartridges across the print medium along a bi-directional scanning path defining a print zone of the printer. An ink jet printhead cartridge, for example, includes both an ink tank containing ink and an ink jet micro-fluid ejection device, i.e., ink jet printhead, for selectively ejecting the ink. Each ink jet printhead cartridge is mounted to the printhead carrier. 
   In the printing industry, there is an increasing desire to reduce size. Accordingly, every component is under scrutiny for optimal performance with minimal size. It is typical for printers to have carrier latches that hold their respective printhead cartridges in place on the printhead carrier. However, such carrier latches may involve several moving parts that often complicate the process of latching. Also, such carrier latches are designed such that a lid swings upward to permit the printhead cartridge to be loaded from the top. Further, such prior carrier latches may be oversized, as well as inefficient from a usability perspective, and provide little or no mechanical advantage to the user during latching. 
   SUMMARY OF THE INVENTION 
   The present invention, in one form thereof, is directed to an imaging apparatus. The imaging apparatus includes a guide frame, and a printhead carrier coupled to the guide frame for mounting a printhead cartridge. The printhead carrier includes a carrier back wall having an upper portion and a lower portion. A printhead cartridge cradle has a front portion and a back portion, the back portion being connected to the carrier back wall. A latch lever has a first proximal end and a first distal end, the first proximal end being pivotably attached to the front portion of the printhead cartridge cradle. The latch lever has at least one cam follower, with each cam follower being located near the first distal end. A carrier lid has a second proximal end, a second distal end, at least one cam, an interior and an exterior. The second proximal end is pivotably attached to the upper portion of the carrier back wall. Each cam is formed at the exterior near the second distal end, and each cam is positioned for progressive engagement by a corresponding cam follower as the latch lever is moved from an open position toward a latched position. 
   The present invention, in another form thereof, is directed to a printhead carrier for mounting a printhead cartridge. The printhead carrier includes a carrier back wall having an upper portion and a lower portion. A printhead cartridge cradle has a front portion and a back portion, the back portion being connected to the carrier back wall. A latch lever has a first proximal end and a first distal end, the first proximal end being pivotably attached to the front portion of the printhead cartridge cradle. The latch lever has a first cam follower spaced apart from a second cam follower. Each of the first cam follower and the second cam follower is located near the first distal end. A carrier lid has a second proximal end, a second distal end, a first cam, a second cam, an interior and an exterior. The second proximal end is pivotably attached to the upper portion of the carrier back wall. The first cam and the second cam are formed at the exterior near the second distal end. The first cam is positioned for progressive engagement by the first cam follower and the second cam is positioned for progressive engagement by the second cam follower as the latch lever is moved from an open position toward a latched position. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above-mentioned an 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 embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
       FIG. 1  is a diagrammatic depiction of an imaging system embodying the present invention. 
       FIG. 2  is a side view of a portion of the imaging apparatus shown in  FIG. 1 ; 
       FIG. 3A  is an end view of a printhead cartridge; 
       FIG. 3B  is a bottom perspective view of the printhead cartridge of  FIG. 3A ; 
       FIG. 4  is an end view of a printhead carrier in the fully open position; 
       FIG. 5A  is a perspective view of the printhead carrier of  FIG. 4 , at the initial stages of mounting a printhead cartridge; 
       FIG. 5B  is a perspective view of the printhead carrier of  FIG. 5A , at an intermediate stage of mounting the printhead cartridge. 
       FIG. 5C  is a perspective view of the printhead carrier of  FIG. 5B  at a further intermediate stage of mounting the printhead cartridge; and 
       FIG. 5D  is a perspective view of the printhead carrier of  FIG. 5C  with the printhead carrier in the latched position. 
   

   DETAILED DESCRIPTION 
   It is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted,” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. In addition, the terms “connected” and “coupled” and variations thereof are not restricted to physical or mechanical connections or couplings. Also, as used herein, “at least one of” means one or more. 
   In addition, it should be understood that some embodiments of the invention may include both hardware and electronic components of modules that, for purposes of discussion, any be illustrated and described as if the majority of the components were implemented solely in hardware. However, one of ordinary skill in the art, and based on a reading of this detailed description, would recognize that, in at least one embodiment, the electronic based aspects of the invention may be implemented in software. As such, it should be noted that a plurality of hardware and software-based devices, as well as a plurality of different structural components may be utilized to implement the invention. Furthermore, and as described in subsequent paragraphs, the specific mechanical configurations illustrated in the drawings are intended to exemplify embodiments of the invention and that other alternative mechanical configurations are possible. 
   Referring to  FIG. 1 , there is shown a diagrammatic depiction of an imaging system  10  embodying the present invention. Imaging system  10  may include a host  12  and an imaging apparatus  14 . Imaging apparatus  14  communicates with host  12  by way of a communications link  16 . Communications link  16  may be established by a direct cable connection, wireless connection or by a network connection such as for example an Ethernet local area network (LAN). As used herein, the term “imaging apparatus” is a device that forms a printed image on a print medium. 
   Alternatively, imaging apparatus  14  may be a standalone unit that is not communicatively linked to a host, such as host  12 . For example, imaging apparatus  14  may take the form of an all-in-one, i.e., multifunction, machine that includes standalone copying and facsimile capabilities, in addition to optionally serving as a printer when attached to a host, such as host  12 . 
   Host  12  may be, for example, a personal computer including an input/output (I/O) device, such as keyboard and display monitor. Host  12  further includes a processor, input/output (I/O) interfaces, memory, such as RAM, ROM, NVRAM, and a mass data storage device, such as a hard drive, CD-ROM and/or DVD units. During operation, host  12  may include in its memory a software program including program instructions that function as an imaging driver, e.g., printer driver software, for imaging apparatus  14 . Alternatively, the imaging driver may be incorporated, in whole or in part, in imaging apparatus  14 . 
   In the embodiment of  FIG. 1 , imaging apparatus  14  includes a controller  18 , a print engine  20  and a user interface  22 .  FIG. 2  shows a side view of imaging apparatus  14 , in the form of a compact ink jet printer. 
   Controller  18  includes a processor unit and associated memory, and may be formed as an Application Specific Integrated Circuit (ASIC). Controller  18  communicates with print engine  20  by way of a communications link  24 . Controller  18  communicates with user interface  22  by way of a communications link  26 . Communications links  24  and  26  may be established, for example, by using standard electrical cabling or bus structures, or by wireless connection. 
   Print engine  20  may be, for example, an ink jet print engine configured for forming an image on a sheet of print media  28 , such as a sheet of paper, transparency or fabric. Print engine  20  may include, for example, a guide frame  29  and a reciprocating printhead carrier  30  slidably coupled to guide frame  29 . Printhead carrier  30  is mechanically and electrically configured to mount and carry at least one printhead cartridge  32 . During a printing operation, guide frame  29  guides printhead carrier  30  back and forth along a bi-directional main scan path  34 , and in turn printhead carrier  30  transports printhead cartridge  32  in a reciprocating manner over an image surface of the sheet of print media  28 . 
     FIG. 2  shows imaging apparatus  14  with printhead carrier  30  in an open position so as to receive printhead cartridge  32 . Printhead cartridge  32  is installed from the front of imaging apparatus  14  toward the back of imaging apparatus  14  in a direction  36 A. Direction  36 B is a direction opposite to direction  36 A. Directions  36 A and  36 B are substantially perpendicular to bi-directional main scan direction, i.e., axis,  34  (see  FIG. 1 ). Since imaging apparatus  14  is configured to facilitate front loading of printhead cartridge  32 , electronic components, such as a printed circuit board  38  (shown in dashed lines) including controller  18 , may be positioned at a location above printhead carrier  30 , thereby contributing to a reduction of the footprint of imaging apparatus  14  when compared to top loading designs. 
     FIGS. 3A and 3B  show a front view, and a bottom perspective view, respectively, of printhead cartridge  32 . Printhead cartridge  32  includes a reservoir body  40 , a top cover  42  and an ink jet printhead  44 . Reservoir body  40  includes a first side  40 - 1 , a second side  40 - 2 , a front side  40 - 3 , a back side  40 - 4 , and a bottom side  40 - 5 . Electrical connections are made to ink jet printhead  44  from controller  18  via a tape automated bond (TAB) circuit  46  located on back side  40 - 4  of printhead cartridge  32 . 
   Printhead cartridge  32  includes a plurality of positioning datums, individually identified as datums  41 A- 1 ,  41 A- 2 ,  41 A- 3 ,  41 B- 1 ,  41 B- 2 , and  41 C. Datums  41 A- 1 ,  41 A- 2 , and  41 A- 3  are located on side  40 - 2 . Datum  41 B- 1  is located on an upper lip just below top cover  42  at back side  40 - 4 . Datum  41 B- 2  is located on bottom side  40 - 5  near front side  40 - 3 . Datum  41 C is located on an upper portion of back side  40 - 4  adjacent to datum  41 B- 1 . Datums  41 A- 1 ,  41 A- 2 ,  41 A- 3 ,  41 B- 1 ,  41 B- 2 , and  41 C may, for example, be in the form of raised surfaces, and are designed to be engaged by corresponding datums in printhead carrier  30 . 
   Ink is contained in reservoir body  40 , and top cover  42  completes the enclosure to contain the ink. Fluid passageways (not shown) provide one or more paths for ink to flow from reservoir body  40  to ink jet printhead  44 . Reservoir body  40  includes a pair of parallel elongate guide members  48 , individually identified as guide member  48 - 1  and guide member  48 - 2 . Guide member  48 - 1  and guide member  48 - 2  extend longitudinally along opposite sides  40 - 1 ,  40 - 2  of reservoir body  40 . 
   Referring now to FIGS.  4  and  5 A- 5 D, printhead carrier  30  includes a carrier back wall  50 , a printhead cartridge cradle  52 , a latch lever  54  and a carrier lid  56 . 
   Carrier back wall  50  has an upper portion  50 - 1  and a lower portion  50 - 2 . A set of electrical contacts  58  are provided on carrier back wall  50 . The set of electrical contacts  58  are communicatively coupled to controller  18 , such as by a multi-conductor cable. The set of electrical contacts  58  provide electrical power and signal communication to TAB circuit  46  when printhead cartridge  32  is installed in printhead carrier  30 . 
   Printhead cartridge cradle  52  has a front portion  52 - 1  and a back portion  52 - 2 . Back portion  52 - 2  is connected carrier back wall  50 . Printhead cartridge cradle  52  includes positioning datums  53 A- 1 ,  53 A- 2 ,  53 A- 3  on a side wall thereof, and a datum  53 B- 2  located on a bottom portion thereof, which are positioned to engage corresponding datums  41 A- 1 ,  41 A- 2 ,  41 A- 3 , and  41 B- 2  of printhead cartridge  32 . Carrier back wall  50  includes positioning datums  53 B- 1  and  53 C positioned to correspondingly engage datums  41 B- 1  and  41 C of printhead cartridge  32 . The datums of printhead carrier  30  define absolute locating positions for positioning printhead cartridge  32  in printhead carrier  30 . 
   Latch lever  54  has a proximal end  54 - 1  and a distal end  54 - 2 . Proximal end  54 - 1  of latch lever  54  is pivotably attached to front portion  52 - 1  of printhead cartridge cradle  52  along a pivot axis  60 . Latch lever  54  has a first cam follower  62 - 1  and a second cam follower  62 - 2 . Each of cam followers  62 - 1 ,  62 - 2  are located near distal end  54 - 2 , and are co-axially arranged along an axis  64 . Axis  64  is parallel to pivot axis  60 . Attached to latch lever  54  is a leaf spring  65  positioned to engage front side  40 - 3  of printhead cartridge  32 . 
   Carrier lid  56  has a proximal end  56 - 1 , a distal end  56 - 2 , interior  56 - 3 , an exterior  56 - 4 , an actuator surface  56 - 5  (see  FIG. 5A ), a first cam  66 - 1  and second cam  66 - 2 . Proximal end  56 - 1  of carrier lid  56  is pivotably attached to upper portion  50 - 1  of carrier back wall  50  along a pivot axis  68 . Pivot axis  68  is parallel to pivot axis  60 . Attached to carrier lid  56  is a leaf spring  69  positioned to engage top cover  42  of printhead cartridge  32 . 
   Each cam  66 - 1 ,  66 - 2  is formed at exterior  56 - 4  of carrier lid  56  near distal end  56 - 2 . Cam  66 - 1  and cam  66 - 2  are oriented to be parallel, and each extends in direction  36 A from distal end  56 - 2  of carrier lid  56  to proximal end  56 - 1  of carrier lid  56 . In one embodiment, for example, the spacing between cam  66 - 1  and cam  66 - 2  in direction  34  is designed to be sufficient such that printhead cartridge  32  may be received between cam  66 - 1  and cam  66 - 2 . Each cam  66 - 1 ,  66 - 2  is positioned for progressive engagement by a corresponding cam follower  62 - 1 ,  62 - 2 , respectively, of latch lever  54  as latch lever  54  is moved from a full open position  70  (see  FIGS. 2 and 4 ) toward a latched position  72  (see  FIG. 5D ). Carrier lid  56  pivots in an angular range of 10 degrees to 15 degrees, e.g., from horizontal, when carrier lid is moved from latched position  72  (see  FIG. 5D ) to full open position  70  (see  FIGS. 2 and 4 ). 
   Each cam  66 - 1  and  66 - 2  has an identical a cam profile P, i.e., shape, that beings at distal end  56 - 2  of carrier lid  56  and ends at a corresponding detent  74 - 1  and detent  74 - 2 , respectively, formed at exterior  56 - 4  at a central region  76  (see  FIG. 5A ) of carrier lid  56  that is between proximal end  56 - 1  and distal end  56 - 2  of carrier lid  56 . Each detent  74 - 1 ,  74 - 2  is sized, shaped and positioned to receive a corresponding cam follower  62 - 1 ,  62 - 2 , respectively, to define the location of latched position  72 , as shown in  FIG. 5D . 
   Carrier lid  56  further includes a pair of elongate guide rails, individually identified as guide rail  80 - 1  and guide rail  80 - 2  formed in interior  56 - 3  of carrier lid  56 . Guide rails  80 - 1 ,  80 - 2  are oriented to be parallel, and each extends in direction  36 A from distal end  56 - 2  of carrier lid  56  to proximal end  56 - 1  of carrier lid  56  to guide printhead cartridge  32  toward carrier back wall  50  as printhead cartridge  32  is loaded into printhead carrier  32 . Guide rail  80 - 1  is spaced apart from guide rail  80 - 2  in a direction perpendicular to direction  36 A, e.g., is spaced apart in a direction parallel to pivot axis  68 , i.e., in bi-directional main scan direction  34 . The spacing is designed to be sufficient such that printhead cartridge  32  may be received between first guide rail  80 - 1  and second guide rail  80 - 2 . Accordingly, guide member  48 - 1  and guide member  48 - 2  of printhead cartridge  32  are slidably engaged by guide rail  80 - 1  and guide rail  80 - 2  of carrier lid  56  as printhead cartridge  32  is loaded into printhead carrier  30 . 
   During a cartridge loading operation, a user inserts the guide members  48 - 1  and  48 - 2  of printhead cartridge  32  onto the pair of elongate guide rails  80 - 1 ,  80 - 2  in carrier lid  56 . The user then contacts latch lever  54  and rotates latch lever  54  toward carrier back wall  50 . At this time, leaf spring  65  of latch lever  54  engages front side  40 - 3  of printhead cartridge  32  and moves printhead cartridge  32  along the pair of elongate guide rails  80 - 1 ,  80 - 2  in carrier lid  56  into contact with positioning datum  53 C on carrier back wall  50  of printhead carrier  30  as latch lever  54  is moved from open position  70  toward latched position  72 . Simultaneously, cam followers  62 - 1 ,  62 - 2  of latch lever  54  engage and ride along the profile P of corresponding cams  66 - 1 ,  62 - 2 , respectively, to force carrier lid  56  to rotate downwardly toward printhead cartridge cradle  52 . During this latching operation, the engagement of cam followers  62 - 1 ,  62 - 2  of latch lever  54  with the arc-shaped cam profile P of the corresponding cams  66 - 1 ,  66 - 2 , respectively, of carrier lid  56  provides a mechanical advantage to the user, thereby requiring minimal force to be applied by the user during the latching operation. 
   As carrier lid  56  rotates downwardly toward printhead cartridge cradle  52 , leaf spring  69  of carrier lid  56  engages top cover  42  of printhead cartridge  32  and moves printhead cartridge  32  into contact with positioning datums  53 B- 1  and  53 B- 2  on printhead cartridge cradle  52  when latch lever  54  is moved from open position  70  toward latched position  72 . A cantilever spring  82  in printhead cartridge cradle  52  forces printhead cartridge  32  into engagement with datums  53 A- 1 ,  53 A- 2  and  53 A- 3  on the side wall thereof. 
   When printhead cartridge  32  is moved into contact with positioning datums  53 B- 1  and  53 B- 2  on printhead cartridge cradle  52 , guide members  48 - 1  and guide member  48 - 2  of printhead cartridge  32  are transversely disengaged from guide rail  80 - 1  and guide rail  80 - 2  of carrier lid  56 , respectively. Leaf spring  65  of latch lever  54  continues to engage front side  40 - 3  of printhead cartridge  32  to hold printhead cartridge  32  against the positioning datums on carrier back wall  50  of printhead carrier  32  with a compression force when latch lever  54  is in latched position  72 . 
   Printhead cartridge installation is complete when cam followers  62 - 1 ,  62 - 2  engage detents  74 - 1 ,  74 - 2 , respectively, of carrier lid  56 , as shown in  FIG. 5D . 
   During a printhead cartridge removal operation, a user applies a downward force on a actuator surface  56 - 5  of carrier lid  56  to cause latch lever  54  to be released from carrier lid  56  by releasing each cam follower  62 - 1 ,  62 - 2  from its corresponding detent  74 - 1 ,  74 - 2 , respectively, of carrier lid  56 . In turn, leaf spring  65  of latch lever  54  extends from the compressed state to propel latch lever  54  to open position  70  to expose front side  40 - 3  of printhead cartridge  32  to facilitate extraction of printhead cartridge  32  in a direction  36 B opposite to direction  36 A, i.e., in a direction away from carrier back wall  50 . Also, at this time a torsion spring  84  causes carrier lid  56  to rotate upwardly at an angle of about 12 degrees from horizontal, thereby lifting printhead cartridge  32  from printhead cartridge cradle  52  through the engagement of guide rails  80 - 1 ,  80 - 2  of carrier lid  56  with the corresponding guide members  48 - 1 ,  48 - 2  of printhead cartridge  32 . The user may then grasp the opposing side walls  40 - 1 ,  40 - 2  of printhead cartridge  32  (see  FIG. 3A ) and pull printhead cartridge  32  in a generally lateral direction  36 B until printhead cartridge  32  is disengaged from the guide rails  80 - 1 ,  80 - 2  of carrier lid  56 . 
   With the embodiment described above, the latching mechanism of the printhead carrier is as much as 29 percent smaller than some prior designs. Also, user forces needed to latch the printhead carrier have been reduced considerably, in some instances by as much as approximately 200 percent. 
   While the embodiment described above is directed to an exemplary single printhead cartridge carrier, those skilled in the art will recognize that the concepts of the present invention may be easily applied to a multiple printhead cartridge environment. 
   The foregoing description of methods and an embodiment of the invention has been presented for purposes of illustration. It is not intended to be exhaustive or to limit the invention to the precise steps and/or forms disclosed, and obviously many modification and variations are possible in light of the above teaching. It is intended that the scope of the invention be defined by the claims appended hereto.