Abstract:
A manually actuated spring loaded latch mechanism for releasably securing a printhead cartridge in a carrier of an ink jet printer. A latch cover engages the printhead cartridge and is secured by an actuator. Depressing the actuator releases the latch cover, which is spring biased to an open position. Further movement of the actuator lifts the printhead cartridge.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention. 
     The present invention relates to ink jet printers, and, more particularly, to a manually actuated latch mechanism for releasably securing an ink cartridge within a carriage assembly of an ink jet printer. 
     2. Description of the Related Art. 
     Ink jet printing involves the ejection of tiny ink droplets through small nozzles in a controlled manner to create the desired image. Ink is supplied from an ink reservoir to a printhead which includes various passage ways from the reservoir to the nozzle orifice. Energy is applied to the ink from an ink droplet generator near each orifice, which may include the application of electrostatic attraction, the application of oscillating forces from piezo elements, the application of heat from heating elements or the like. 
     Ink jet printers typically include an ink jet cartridge containing the ink reservoir and a nozzle plate containing the nozzle orifices. It is known to provide the ink cartridge on a carriage assembly. The carriage assembly is moved in transverse directions relative to an advance direction of a print medium being transported through the ink jet printer. As the carriage assembly traverses across the print medium, the ink is jetted at selected locations onto the print medium. In the case of a monochrome printer, a single ink is selectably jetted onto the print medium at pixel locations; and, in the case of a multi-color printer, multiple inks are selectively jetted onto a print medium at pixel locations. 
     It is necessary that the ink cartridge or cartridges be precisely located in the carriage assembly, and it is known to provide datum surfaces on the cartridge and in the carriage to properly reference the cartridge to an exact location. It is also necessary that the cartridge or cartridges be adequately secured in the carriage so that the rapid back and forth movement of the carriage does not cause a cartridge to become unseated. 
     Since the ink jet cartridge is a consumable item, having a limited supply of ink therein, it is necessary that the cartridge be replaced from time to time. Such replacement should be an intuitive and simple operation, easily performed by non-technically trained individuals. 
     Various types of latch mechanisms are known and have been used with varying results. Some mechanisms work well in locking and releasing the cartridge, but the cartridge remains difficult to grasp and remove even after the cartridge has been released. 
     What is needed in the art is a manually actuated latch mechanism for securing in a releasable manner an ink jet cartridge in a carriage assembly which, by simple operation, both releases the latch and unseats the cartridge. 
     SUMMARY OF THE INVENTION 
     The present invention provides a manually actuated carrier latch mechanism for an ink jet printer that provides a user friendly interface for installing and removing a printhead from a carrier. 
     The invention comprises, in one form thereof, a latch mechanism for releasably securing a printhead cartridge in a printer. The latch mechanism comprises a cradle for receiving a printhead, the cradle including datum pads against which the printhead is referenced. A latch cover has a pivotal connection to the cradle. The latch cover includes structure for engaging a printhead in two perpendicular planes. An actuator is provided for engaging the latch cover in a closed position. The actuator is adapted for releasing the latch cover by movement of the actuator and for moving a printhead cartridge installed in the cradle by further movement of the actuator. 
     In another form thereof, the invention provides a printer with a printhead cartridge having a bottom, a top, first and second laterally spaced sides, an inner end and an outer end. The cartridge includes at least one datum pad on the bottom, at least one datum pad on the inner end and at least one datum pad on one of the sides. A carriage is adapted for receiving the cartridge, and includes carriage datum pads for mating with each of the datum pads on the cartridge. Biasing means in the carriage operates against the other side of the cartridge. A latch cover is releasably secured overlying the cartridge top and the outer end. An actuator engages the latch cover in a closed position. The actuator is adapted for releasing the latch cover by movement of the actuator, and for lifting the printhead cartridge by further movement of the actuator. 
     The invention provides, in still another form thereof, a method of unseating an ink jet cartridge installed in a carriage assembly of an ink jet printer, having steps of providing the carriage assembly with a cartridge cradle, a latch cover pivotally connected to the cradle and an actuator for engaging the latch cover, the actuator being pivotally connected to the cradle; releasing the latch cover by moving the actuator; and moving the printhead by further movement of the actuator. 
     An advantage of the present invention is providing a user-friendly interface for installation and removal of a printhead cartridge in an ink jet printer. 
     Another advantage is providing a locking mechanism that promotes proper seating of a printhead cartridge in a printer carriage. 
     Yet another advantage is providing a mechanism that unlocks a printhead cartridge from a carrier, unseats the cartridge, and repositions the cartridge for easy removal. 
    
    
     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 perspective view of a portion of an ink jet printer embodying the present invention; 
     FIG. 2 is a perspective view of a printhead cartridge; 
     FIG. 3 is a perspective view of a carrier of the present invention; 
     FIG. 4 is a perspective view of the carrier with two cartridges therein, one cartridge being locked in position and the other being unlocked and unseated; 
     FIG. 5 is a perspective view of the carrier and one of the cartridges; 
     FIG. 6 is a perspective view of a latch cover according to the invention; 
     FIG. 7 is an enlarged view of the area of the latch cover connection to the carrier; 
     FIG. 8 is an elevational view of the cover, with a side removed, and the cartridge; 
     FIG. 9 is a perspective view of an actuator of the invention; 
     FIG. 10 is an enlarged, fragmentary perspective view of the cartridge and carrier, 
     FIG. 11 is a side view of the carrier and cartridge at an intermediate point during cartridge removal or installation; and 
     FIG. 12 is a view similar to FIG. 11, but at a more advanced point during cartridge removal. 
     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  of the present invention, which generally includes one or more ink jet print cartridge  12  carried by a carriage assembly  14 . Carriage assembly  14  moves back and forth across the printer during normal printing operations to position print head cartridge or cartridges  12  as necessary for the deposit of ink droplets at precise locations on the print medium (not shown). Ink jet cartridge  12  may be of various known constructions and includes one or more chambers for carrying ink therein to be jetted as ink droplets at selected locations on the print medium. In the embodiment shown, two ink jet cartridges  12  are shown, indicated  12 A and  12 B. Cartridge  12 A is assumed to have a single chamber carrying a single ink, and cartridge  12 B is assumed to include multiple chambers carrying different inks for color printing. 
     Each ink jet cartridge (FIG. 2) includes a top  16 , a bottom  18 , an inner end  20  and an outer end  22 . First and second sides  24  and  26  are disposed between top  16  and bottom  18 , and between inner end  20  and outer end  22 . A printhead nozzle plate  28  is provided at bottom  18 . 
     To properly reference printhead cartridge  12  in printer  10 , as will be described in greater detail hereinafter, a plurality of datum pads are provided as reference surfaces, for positioning purposes. One or more datum pads  30 ,  32 ,  34  are provided on one of sides  24  and  26 , three such datum pads  30 ,  32  and  34  being shown in the drawings. Datum pads  30 ,  32  and  34  define a primary datum plane of cartridge  12 . 
     A secondary datum plane of cartridge  12  is defined by datum pads  36  and  38  on inner end  20  and bottom  18 , respectively. A single datum pad  40  is provided on inner end  20 , for defining a tertiary datum plane of cartridge  12 . Those skilled in the art will understand that more or fewer datum pads may be used to define the primary, second and tertiary datum planes. The three datum planes ensure that the printhead is fully constrained when latched in the carrier, and each of the three planes is perpendicular to the other two planes. 
     Carriage assembly  14  defines a cradle  50  adapted for receiving and retaining, in suitable nested position therein, each cartridge  12 . Carriage assembly  14  may define one or more cradles  50  and, for example, in a color printer may define two cradles  50 , one for a black ink cartridge  12 A and one for a color ink cartridge  12 B. FIG. 3 shows a carriage assembly  14  having two cradles  50 , with similar components of each designated with same reference numbers. 
     Carriage assembly  14  includes a carriage cover  52 , having one or more padded liners  54  and  56  on the inside thereof, one such padded liner  54 ,  56  for each cradle  50 . Liners  54  and  56  may be synthetic foam, or the like. 
     Cradle  50  generally defines a three sided enclosure for receiving cartridge  12 , and includes primary datum plane datum pads  60 ,  62  and  64  for mating with datum pads  30 ,  32  and  34  of cartridge  12 . Cradle  50  further includes secondary datum plane datum pads  66 ,  68  for mating with datum pads  36  and  38  of cartridge  12 . Cradle  50  further includes a tertiary datum plane datum pad  70  for mating with datum pad  40  of cartridge  12 . Thus, by securing cartridge  12  in cradle  50 , with datum pads  30 ,  32 ,  34 ,  36 ,  38  and  40  properly referenced against datum pads  60 ,  62 ,  64 ,  66 ,  68  and  70 , respectively, cartridge  12  is held in cradle  50  in properly oriented position for operation of printer  10 . 
     To properly hold cartridge  12  in cradle  50 , biasing force is necessary. To effectuate such biasing force along the primary datum plane defined by datum pads  30 ,  32  and  34  mated against datum pads  60 ,  62  and  64 , a side bias spring  72  (FIG. 1) is provided, operating against cartridge  12  on the side opposite the side including datum pads  30 ,  32  and  34 . Thus, as shown in the drawings, datum pads  30 ,  32  and  34  are provided on first side  24  of cartridge  12  and bias spring  72  operates against second side  26  of cartridge  12 . 
     A latch assembly  80  is provided for securing cartridge  12  in cradle  50 , and for providing biasing force along the secondary datum plane defined by datum pads  36  and  38  seated against datum pads  66  and  68  as well as biasing force along the tertiary datum plane defined by datum pad  40  mated against datum pad  70 . Latch mechanism  80  includes a latch cover  82  and an actuator  84 . Cover  82  operates against cartridge top  16  and cartridge outer end  22 , while actuator  84  performs both release and locking functions, as well as a lifting function on cartridge  12 , each to be described in greater detail hereinafter. 
     Latch cover  82  (FIG. 6) includes a latch cover top  86  substantially overlying cartridge top  16 , and a downwardly depending portion  88  generally along outer end  22  of cartridge  12  when latch mechanism  80  is in a closed or locked position as shown in FIG.  1 . Latch cover top  86  is joined to carriage assembly  14  by a pivotal connection  90  at an end of latch cover top  86  opposite the end having downwardly depending portion  88 . While any suitable pivotal connection may be used, the embodiment shown includes a pin  92  extending outwardly on one side of latch cover top  86  and a hole  94  (FIG. 6) defined in an opposite side of latch cover top  86 . A complimentary hole  96  and pin  98  are provided on carriage assembly  14  (FIG.  3 ), such that pin  92  is received in hole  96  and pin  98  is received in hole  94 . 
     A latch torsion spring  100  (FIG.  7 ), is provided at pivotal connection  90 , for biasing latch cover  82  toward an open position, as shown in FIG.  4 . 
     On an underside  102  of latch cover top  86 , a plunger  104  is provided. Plunger  104 , shown in an enlarged view of FIG. 8, is rotatable and vertically movable, and biased by a spring  106 . Plunger  104  includes a curved, ramp-like surface  108  for mating against a complementary ramp-surface  110  of a body  112  provided on, or as part of, cartridge top  16 . The generally downwardly biasing force of spring  106  on plunger  104  provides the secondary datum plane and tertiary datum plane biasing forces through ramp surfaces  108  and  110 . The curvature of surface  108  assures that the biasing force on surface  110  is normal to, and generally centered on surface  110 . 
     Downwardly depending portion  88  of latch cover top  86  includes an outwardly extending lip  114  at the lower end thereof, for functioning with actuator  84 , in a manner to be described subsequently herein, to secure latch mechanism  80  in the closed or locked position. 
     Actuator  84 , shown individually in FIG. 9, includes first and second arms  120  and  122  spaced from each other, and provided generally along second side  26  and first side  24 , respectively, of cartridge  12 , near cartridge bottom  18 . Each first arm  120  and second arm  122  includes a first or inner end  124  and  126 , respectively, and a second or outer end  128  and  130 , respectively. First arm  120  is pivotally connected to carriage assembly  14  at a pivot point  132  intermediate first end  124  and second end  128 . A lift bar  136  is disposed between first arm  120  and second arm  122  generally at first end  124  and first end  126  thereof, with lift bar  136  being disposed beneath cartridge  12 . An actuator touch pad  138  is disposed between first arm  120  and second arm  122  generally at second end  128  and second end  130  thereof, respectively. Touch pad  138  is disposed generally outwardly of downwardly depending portion  88  with latch cover  82  in the closed or locked position. Touch pad  138  includes a bottom edge  140  which overlies outwardly extending lip  114  in the locked position of latch cover  82 . 
     As shown most clearly in FIG. 9, first arm  120  is generally step-shaped in side view, having a generally horizontal lower segment  142  and an upper segment  144  joined by a riser  146 . Second arm  122  has a generally vertical inner segment  148  and a generally horizontal outer segment  150 , joined by a curved segment  152 . Pivot  132  is provided generally at a lower portion of riser  146 , between lower segment  142  and upper segment  144  of first arm  120 . Thus, downward pressure on touch pad  138 , causing downward movement thereof, also causes outward movement of touch pad  138 , away from downwardly depending portion  88 . At the same time, first ends  124  and  126  are caused to move upwardly, raising lift bar  136 . An actuator spring  154  is provided, biasing first arm  120  in the upward or locked direction of touch pad  138 . Movement of touch pad  138  is guided by a knob or knobs  156  traveling in a guide bracket  158 . 
     For removal of a printhead cartridge  12 , from the closed or locked position shown in FIG. 1, wherein cartridge  12  is secured in cradle  50 , a user of the device pushes downwardly on touch pad  138 , causing downward and outward movement of pad  138  away from downwardly depending portion  88  of latch cover  82 . From a position in which bottom edge  140  overlaps outwardly extending lip  114 , bottom edge  140  is moved away from lip  114 , as arm  120  is pivoted about pivot point  132 , thus freeing latch cover  82  from engagement with actuator  84 . FIG. 5 illustrates a time in the procedure just after lip  114  has been released, and latch cover  82  has begun to rise. Latch torsion spring  100  causes latch cover  82  to rotate fully upwardly to an opened position illustrated in FIG.  4 . Padded liners  54 ,  56  absorb energy from latch cover  82  striking carriage cover  52  as latch cover  82  is rotated about pivotal connection  90  to a fully opened position. 
     Continued downward movement of touch pad  138  raises lift bar  136  into engagement against bottom  18  of cartridge  12  (FIG.  11 ). Still further downward movement of touch pad  138  lifts cartridge  12  away from its nested position in cradle  50  (FIG.  12 ). Thus freed, elevated and exposed, cartridge  12  can be readily grasped for removal from carriage assembly  14 . 
     It should be noted that upon cessation of downward pressure on touch pad  138 , actuator spring  154  rotates first arm  120  about pivot point  132 , elevating touch pad  138  to the upward position illustrated in FIG.  4 . However, cartridge  12  will remain in its elevated position, as the side biasing force exerted by side bias spring  72  is sufficient to wedge cartridge  12  in the lifted position. 
     It should be noted further that the stored potential energy in plunger spring  106  operating against plunger  104 , and thereby ramp surface  108  against ramp surface  110 , further assists in elevating cover  82  to its fully opened position. Latch torsion spring  100  will retain latch cover  82  in the elevated or opened position. 
     For installation of a printhead cartridge  12 , if latch cover  82  has been closed without a cartridge  12  in cradle  50 , touch pad  138  is depressed to release latch cover  82 , allowing latch cover  82  to rotate to its elevated position, as described above. Printhead cartridge  12  is then placed in generally proper position in cradle  50 . Cartridge  12  is properly positioned and seated in cradle  50  by pushing downwardly on latch cover top  86 , causing ramp surfaces  108  and  110  to engage, and, during initial stages, causing depending portion  88  to engage against outer end  22 , thereby pushing cartridge  12  both downwardly and inwardly. 
     To assist in directing cartridge  12  properly into cradle  50 , cradle  50  includes a plurality of features  160 , such as ramps or transitions, to guide printhead cartridge  12  into and out of its properly seated position. Features  160  provide sliding and directing surfaces for cartridge  12  between its seated position as shown in FIG.  5  and its elevated position as shown in FIG.  4 . To further aid in directing cartridge  12  to a proper nested position, one or more features  160 , may be provided as a V-shaped protuberance  162  received in a V-shaped opening  164  (FIG.  3 ). Initially protuberance  162  is received in a wide region of V-shaped opening  164 , and continued downward movement of cartridge  12  directs protuberance  162  downwardly in opening  164  to its final resting position. As illustrated in FIG. 2, a bottom surface of protuberance  162  defines datum pad  36 , and the bottom of groove  164  defines datum pad  66 . 
     As latch cover  82  is pressed to its lower most position, lip  114  slides past touch pad  138 , and specifically bottom edge  140  thereof, until lip  114  is directly beneath bottom edge  140 . FIG. 5, previously described as illustrating the position of cover  82  just after lip  114  has been released, also illustrates the cover position just prior to lip  114  sliding past edge  140 , as cartridge  12  is installed. Since actuator spring  154  biases touch pad  138  into the upper or lifted position, as lip  114  is slid past bottom edge  140 , touch pad  138  is biased upwardly and inwardly such that bottom edge  140  overlies lip  114 . Releasing downward pressure on latch cover  82  causes slight upward movement of latch cover  82  by latch torsion spring  100 , and, when a cartridge  12  is installed, by plunger spring  106  through plunger  104 , until lip  114  engages against bottom edge  140 . The combined effect of actuator spring  154  biasing touch pad  138  upwardly and inwardly and latch torsion spring  100  (and plunger spring  106  if a cartridge  12  is installed) biasing latch cover  82  upwardly causes locked engagement of bottom edge  140  against lip  114 . 
     It should also be noted that, as cartridge  112  is inserted into cradle  50 , and pushed downwardly by latch cover  82 , side biasing spring  72  and continued relative movement of ramp surface  108  along ramp surface  110  by plunger  104  properly mates datum pads  30 ,  32 ,  34 ,  36 ,  38  and  40  against datum pads  60 ,  62 ,  64 ,  66 ,  68  and  70 . 
     The present invention provides a user friendly interface for installing and removing a printhead cartridge from a carrier. Spring loading the latch mechanism ensures proper latching of the device upon installation of the cartridge, and facilitates removal of the cartridge by readily opening and lifting the cover away from the installed cartridge. A single movement of the actuator both unlocks or delatches the latch mechanism, and lifts the cartridge to unseat the cartridge and expose the cartridge for ready removal thereof Installation and latching are facilitated by requiring only gross positioning of the cartridge, with final positioning thereof being effectuated by the latch mechanism upon closing of the latch. Locking of the latch mechanism is automatic in performing the closing function. 
     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 known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.