Patent Publication Number: US-6655793-B2

Title: Print cartridge supporting apparatus

Description:
BACKGROUND OF THE DISCLOSURE 
     An ink jet printer forms a printed image by printing a pattern of individual dots at particular locations of an array defined for the printing medium. The locations are conveniently visualized as being small dots in a rectilinear array. The locations are sometimes called “dot locations,” “dot positions,” or “pixels”. Thus, the printing operation can be viewed as the filling of a pattern of dot locations with dots of ink. 
     Ink jet printers print dots by ejecting very small drops of ink onto the print medium, and typically include a movable print carriage that supports one or more print cartridges each having ink ejecting nozzles. The print carriage traverses back and forth over the surface of the print medium, and the nozzles are controlled to eject drops of ink at appropriate times pursuant to command of a microcomputer or other controller, wherein the timing of the application of the ink drops is intended to correspond to the pattern of pixels of the image being printed. Typically, a plurality of rows of pixels are printed in each traverse or scan of the print carriage. The particular ink ejection mechanism within the printhead may take on a variety of different forms known to those skilled in the art, such as those using thermal printhead or piezoelectric technology. For instance, two earlier thermal ink jet ejection mechanisms are shown in commonly assigned U.S. Pat. Nos. 5,278,584 and 4,683,481. In a thermal system, an ink barrier layer containing ink channels and ink vaporization chambers is disposed between a nozzle orifice plate and a thin film substrate. The thin film substrate typically includes arrays of heater elements such as thin film resistors which are selectively energized to heat ink within the vaporization chambers. Upon heating, an ink droplet is ejected from a nozzle associated with the energized heater element. By selectively energizing heater elements as the printhead moves across the print medium, ink drops are ejected onto the print medium in a pattern to form the desired image. 
     Certain ink jet printers employ disposable print cartridges that are replaced when empty, and it is often difficult to accurately and consistently position a print cartridge in the printer relative to another print cartridge and relative to the entire printer. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Features and advantages of the disclosure will readily be appreciated by persons skilled in the art from the following detailed description when read in conjunction with the drawing wherein: 
     FIG. 1 is a schematic partial cut away perspective view of a printer embodying principles disclosed in the specification. 
     FIG. 2 is a schematic perspective view of an ink jet print cartridge of the printer of FIG.  1 . 
     FIG. 3 is a schematic side elevational view of the ink jet print cartridge of FIG.  2 . 
     FIG. 4 is a schematic perspective view of the print carriage of the printer of FIG.  1 . 
     FIG. 5 is a schematic front elevational view of a chute and latch assembly of the print carriage of FIG.  4 . 
     FIG. 6 is a schematic front partial perspective view of the print carriage of FIG. 4, with the cartridges and the latch assemblies removed. 
     FIG. 7 is a schematic rear partial perspective view of the print carriage of FIG. 4, with the cartridges and the latch assemblies removed. 
     FIG. 8 is a schematic sectional elevational view of a chute of the print carriage of FIG.  4 . 
     FIG. 9 is a schematic sectional elevational view of a side wall of a chute of the print carriage of FIG.  4 . 
     FIG. 10 is a schematic sectional elevational view of a chute and latch assembly of the print carriage of FIG. 4 showing the latch assembly in a latched or closed position. 
     FIG. 11 is a schematic plan view of a clamp structure of the latch assembly of the print carriage of FIG.  4 . 
     FIG. 12 is a schematic perspective view of a clamp blade of the clamp structure of FIG.  11 . 
     FIGS. 13-17 schematically depict the latch assembly at various states as it is moved to a latched or closed position. 
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     Referring now to FIG. 1, schematically depicted therein is an ink jet printer  114  partially cut away and with its front loading door removed. The printer includes a case or housing  115  and carriage drive motor  116  mounted on a chassis. The motor drives a belt  118  back and forth as the drive motor reverses direction. The drive belt  118  is attached to a print carriage  119  that scans laterally back and forth along a carriage scan axis CA from left to right and right to left over a print medium  117 . The print carriage  119  contains two externally similar thermal ink jet print cartridges  11  located side by side. For example, one of the print cartridges can contains black ink while the other has three ink chambers containing magenta, yellow and cyan inks. The horizontal scanning motion of the print carriage  119  is guided by a slider rod  121 . Located in the rear of the carriage  119  is an encoder, not shown, that reads a position encoder strip  122  provides information of the location of the print carriage  119  along the carriage axis CA. 
     The print carriage  119  includes a cartridge latching system that positions the print cartridges  11  relative to an orthogonal coordinate system shown in FIG.  4 . The X axis is parallel to the carriage scan axis. The Y axis is parallel to and opposite a media advance path which for example extends horizontally out of the printer  114 , such that the X and Y axes define a horizontal XY plane. The Z axis extends vertically to the XY plane. 
     Referring now to FIGS. 2 and 3, the print cartridge  11  more particularly includes a print cartridge body comprised of a rear wall  24 , a left side wall  25 , a right side wall  26 , a front wall  27 , and a bottom wall  28  that includes a snout section  28   a  that supports an ink jet printhead  15 . A top wall or lid  31  is attached to the upper edges of the front, side, and rear walls, and includes margins or lips  29  that extend beyond the front and side walls. A latch catch or feature  50  is disposed on the lid  31  close to the top boundary of the rear wall  24 . The latch feature  50  extends upwardly from the top wall  31  and includes a front latch surface  50   a  and a rearwardly extending surface  50   c  that intersects the top of the front latch surface  50  at a front lateral edge  50   b . By way of illustrative example, the front latch surface  50   a  is perpendicular to the lid  31  while the rearwardly extending surface  50   c  can be a ramped surface that extends downwardly and rearwardly from the top of the front latch surface  50   a . Alternatively, the rearwardly extending surface of the latch feature can comprise a horizontal surface  50   c as illustrated in FIG.  3 . As described further herein, a clamp pushes down on a top portion of the front lateral edge  50   b.    
     Located in the vicinity of the intersection of the left side wall  25 , rear wall  24  and snout  28   a  are a printhead cartridge X axis datum PX 1 , a first printhead cartridge Y axis datum PY 1 , and a first printhead cartridge Z axis datum PZ 1 . Located in the vicinity of the intersection of the right side wall  26 , rear wall  24  and snout  28   a  are a second printhead cartridge Y axis datum PY 2  and a second printhead cartridge Z axis datum PZ 2 . A third printhead cartridge Y axis datum PY 3  is located in the upper portion of the rear wall  24 . The print cartridge Y axis datums generally comprise lands that are configured to be generally orthogonal to the Y axis when the cartridge is installed in the print carriage  119 . The print cartridge Z axis datums comprise lands that are configured to be generally orthogonal to the Z axis when the print cartridge is installed in the print carriage  119 . The print cartridge X axis datum comprises a land that is configured to be generally orthogonal to the, X axis when the print cartridge is installed in the print carriage  119 . 
     Located on the rear wall  24  of the print cartridge is a flexible circuit  33  that provides electrical interconnection between the printer and the printhead  15 , and routes electrical signals to the appropriate heater resistors of the printhead during printing. 
     Referring now to FIGS. 4-9, the print carriage  119  more particularly includes a support base  126  and two C-shaped bearings  128  located at the ends of the base  126 . These C-shaped bearings  128  slidably support the print carriage  119  on the slider rod  121 . The print carriage  119  further includes two chutes  131  that each receive, hold, and align an ink jet print cartridge  11 . Both chutes are constructed and operate similarly. Each chute includes a rear wall  135  that comprises for example a portion of the base  126 , a left side wall  133  that extends from the rear wall  135 , and a right side wall  134  that extends from the rear wall  135  and is generally parallel to the left side wall  133 . 
     Carriage datums CY 1 , CZ 1  and CX 1  formed for example as part of the base  126  are located at the bottom of the chute  131  in the vicinity of the intersection of the left side wall  133  the rear wall  135 , while carriage datums CY 2  and CZ 2  for example as part of the base  126  are located at the bottom of the chute  131  in the vicinity of the vicinity of the intersection of the right side wall  134  and the rear wall  135 . A carriage datum CY 3  is located on the rear wall  135 . 
     A resilient contact circuit  137  is located on the rear wall  135  of the chute and contains electrical contacts that are urged against corresponding contacts on the flex circuit  33  of the print cartridge  11 . The resilient contact circuit  137  further functions as a resilient element that urges the print cartridge datums PY 1 , PY 2  against carriage datums CY 1 , CY 2  when the print cartridge  11  is installed. By way of illustrative example, the resilient contact circuit  137  comprises a flexible circuit and resilient pad located between the flexible circuit and the rear wall  135 . 
     A cantilever spring  146  is located adjacent the right side wall  134 , and functions to urge the print cartridge away from the right side wall  134  along the X-axis, so that the print cartridge datum PX 1  is snugly engaged against the carriage datum CX 1 . 
     Located in each side wall  133 ,  134  is a shaped guide channel  140 . The guide channels  140  engage lips  29  of the print cartridge  11 , and guide the cartridge at an appropriate elevation and pitch (or rotation) of the cartridge about the X axis as the cartridge is inserted, so as to guide the cartridge into the general vicinity of the carriage datums. By way of illustrative example, each guide channel comprises upper and lower rails  140   a ,  140   b  or a recessed slot having appropriate sides. 
     A cross bar  139  spans the upper part of the front portion of chute  131  and is located above the guide channels  140 . The cross bar prevents insertion of the cartridge from above, and further prevents spreading of the side walls in the event the cartridge is forced too low in the chute. 
     Located at the top of each chute  131  is a hinged latch assembly  150  that includes a latch support arm  151  that is rotatably attached by a hinge  153  to the top of the rear wall  135  so as to be hingably rotatable about a latch arm rotation axis AR 1  that can be approximately or generally parallel to the X-axis. The latch support arm  151  includes a top portion  151   a  that extends from the hinge  153  and a front portion  151   b  that is hingeably attached at the distal end of the top portion  151   a . Latch hooks  155  are located at the ends of the front portion  151   b  for engaging latch tabs  157  disposed at the front of the side walls  133 ,  134 . The front portion  151   b  can be biased by a spring  152  to rotate toward the lower side of the top portion  151   a.    
     Referring now to FIGS. 10-12, the hinged latch assembly further includes a pivoting biased clamp lever or base  159  hingeably attached to the lower side of the latch arm  151  by hinge posts  161  so as to be rotatable about a clamp rotation axis AR 2  that is displaced from the latch arm rotation axis AR 1  and can be approximately or generally parallel to the X-axis. The clamp lever  159  extends generally toward the chute rear wall  135  when the latch is closed, as particularly shown in FIG.  10 . The clamp lever  159  is biased by a spring  163  to rotate away from the latch arm  151  and is resiliently or resistingly deflectable toward the latch arm  151 . Stops  165  on either side of the clamp lever  159  limit the rotation of the clamp lever  159  away from the latch arm  151 . The hinge posts  161  can be engaged in slots that allow slight movement toward and away from the latch arm, which allows the clamp lever  159  to pivot slightly about the stops  165 . 
     The pivoting clamp lever  159  further includes tracks  171  in which a sliding clamp arm  173  is slidably located for movement generally along a clamp translation axis AT that is approximately or generally orthogonal to the clamp rotation axis AR 2 . An acute angle is formed by the clamp translation axis AT and an imaginary line IL that passes through the latch arm rotation axis AR 1  and the clamp rotation axis AR 2 . The sliding clamp arm  173  is biased by a spring  175  to move along the pivoting clamp lever  159  away from the clamp hinge  161 , and is resiliently or resistingly deflectable toward the clamp rotation axis AR 2 . Stops  177  limit the displacement of the sliding clamp arm  173 . A clamp blade  179  is affixed to the distal end of the sliding clamp arm  173 . 
     As more particularly depicted in FIG. 12, the clamp blade  179  can generally resemble a bulldozer blade and includes an upper or leading lateral edge  179   a , an upper ramp surface  179   b  adjacent the leading lateral edge  179   a , a lower surface  179   c  adjacent the upper ramp surface  179   b , and a lower or trailing lateral edge  179   d  adjacent the lower surface  179   c . The trailing edge  179   d  can be curved or radiused, for example. The upper ramp surface  179   b  and the lower surface  179   c  form an interior angle A that can be an obtuse angle, for example about 135 degrees. Generally, the angle A can be larger than the exterior angle between the front surface  50   a  and the top surface  50   c ,  50   c ′ of the latch feature  50  of the print cartridge  11 . The clamp blade can have a width dimension that is generally aligned with the X-axis, and such width can be configured to compensate for the rocking imparted by the offset between the location of the force applied by cantilever spring  146  and the location of the carriage X-axis datum CX 1 . 
     In use, the cartridge  11  is inserted generally horizontally into the chute  131 . The guide channels  140  control the elevation and the pitch about the X axis of the cartridge  11  as it is inserted into the chute  131 , such that print cartridge datums PY 1 , PY 2  move over the corresponding carriage datums CY 1 , CY 2 . The print cartridge  11  can typically be left by the user in a position wherein the print cartridge is pitched up, as depicted in FIG.  13 . The latch arm  151  is then rotated downwardly toward a latched position, and FIGS. 14-17 schematically depict various states of the latch assembly as it is moved to the latched position. 
     As depicted in FIG. 14, the clamp blade  179  contacts the top wall  31  of the print cartridge  11 , for example with the trailing edge  179   d , and slides toward the latch feature  50 . As the clamp blade  179  contacts the top wall  31  of the print cartridge and slides along such top wall, it pushes down on the top wall. In this manner, the initial force on the print cartridge  11  is primarily down along the Z-axis, which tends to seat the print cartridge datums PZ 1 , PZ 2  against the carriage Z-datums CZ 1 , CZ 2 . 
     As depicted in FIG. 15, the leading edge  179   a  of the clamp blade  179  eventually contacts the front surface  50   a  of the latch feature  50  and pushes on such surface generally along the Y-axis. The push generally along the Y-axis causes the print cartridge to pivot about the X axis so that the print cartridge datum PY 3  snugly seats against the carriage datum CY 3 , as shown in FIG.  16 . The resilient contact circuit  137  is located so as to cause the print cartridge datums PY 1 , PY 2  to seat snugly against the carriage datum CY 1 , CY 2  when the print cartridge datums PZ 1 , PZ 2  are engaged with the carriage datums CZ 1 , CZ 2 , and the print cartridge datum PY 3  is engaged with the carriage datum CY 3 . 
     As depicted in FIG. 16, the clamp blade  179  pivots as the latch arm  151  continues to be rotated toward the latched position, and the ramp surface  179   b  of the clamp blade  179  eventually contacts the front lateral edge  50   b  of the latch feature and lifts the clamp blade off the top wall  31  of the print cartridge. 
     As depicted in FIG. 17, the ramp surface  179   b  slides across the front lateral edge  50   b  of the latch feature and eventually the clamp blade lower surface  179   c  contacts the front surface  50   a  of the latch feature so that the top of the front lateral edge  50   b  and the front surface  50   a  of the latch feature are engaged by the ramp surface  179   b  and the lower surface  179   c  of the clamp blade, as depicted in FIG.  10 . For example, the top of the front lateral edge  50   b  is engaged by a portion of the ramp surface  179  that is near the vertex of the angle A. The clamp blade is clear of the top surface of the print cartridge when the top front surfaces of the latch feature are engaged by the clamp blade ramp and lower surfaces. 
     The latch arm  151  is further displaced to engage the latch hooks  155  with the latch tabs  157 , which allows the clamp blade  179  to continually push on the top of the latch feature  50  generally along the Z-axis and on the front of the latch feature generally along the Y-axis, so that the print cartridge datums PY 1 , PY 2 , PY 3 , PZ 1 , PZ 2  are continually engaged with the corresponding carriage datums CY 1 , CY 2 , CY 3 , CZ 1 , CZ 2 . This is the result the resilient deflection of the clamp blade as it was pushed against the top surface of the print cartridge and the latch feature. 
     Generally, the clamp blade  179  at first pushes down on the print cartridge generally along the Z-axis to engage the print cartridge Z-axis datums PZ 1 , PZ 2  with the carriage Z-axis datums CZ 1 , CZ 2 , and then pushes on the latch feature  50  to engage the print cartridge Y-axis datums PY 1 , PY 2 , PY 3  with the carriage Y-axis datums CY 1 , CY 2 , CY 3 . The clamp then engages the latch feature  50  of the print cartridge  11  to continually bias the print cartridge Z-axis and Y-axis datums against the corresponding carriage Z-axis and Y-axis datums. 
     In addition to the Z and Y seating achieved by the clamp, the wire spring  146  pushes the cartridge generally along the X axis so that the print cartridge datum PX 1  is snugly engaged with the carriage datum CX 1 . In this manner, the print cartridge datums are snugly seated against corresponding carriage datums, which fixes the position of the print cartridge in the chute  131 . 
     Although the foregoing has been a description and illustration of specific embodiments, various modifications and changes thereto can be made by persons skilled in the art without departing from the scope of the invention as defined by the following claims.