Patent Publication Number: US-8979251-B2

Title: Fluid cartridge

Description:
RELATED APPLICATION 
     The present specification is a continuation of co-pending U.S. application Ser. No. 13/765,451, filed 12 Feb. 2013, which is a bypass continuation of PCT/US2010/053692, filed 22 Oct. 2010, entitled “FLUID CARTRIDGE,” the contents of all above-named applications are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     Fluid cartridges are subassemblies to be exchanged with a corresponding fluid ejection assembly. A common fluid cartridge is an ink cartridge. A common fluid ejection assembly is a printer. In general, two types of ink cartridges can be distinguished. A first type consists of an integrated print head cartridge, wherein the cartridge comprises a print head. A second type consists of an individual ink container. An ink cartridge is connected to a receiving structure of a printer. The receiving structure and the ink cartridges are provided with the proper interfaces for guiding ink from the cartridge to the print head for printing. In addition to the ink interface, an air interface, a keying interface, an electrical interface and an alignment interface can be provided in the ink cartridge and its receiving structure. The air interface transports air to and from the cartridge, mostly for pressure control inside the cartridge. The keying interface ensures that the respective cartridge is seated in the proper ink cartridge receiving structure. The alignment interface ensures that the interfaces are well aligned for connection. The electrical interface sends electrical signals between a printer control circuit and the ink cartridge. The signals may relate to ink cartridge characteristics. 
     An extra lock is usually provided to maintain substantially air and liquid tight connections between the cartridge and the receiving structure. The extra lock should also maintain the electrical connection. A known locking technique involves the use of a bail to keep the cartridge sealed to the receiving bay. Another known locking technique uses a deforming snap finger that engages a notch to keep the cartridge sealed. 
     The known lock mechanisms tend to consume a relatively large amount of space within the printer. In addition, significant force may be needed to establish the lock. In some cases, the cartridge is inserted in an inclined orientation, after which it is rotated back to normal position to make the interfaces engage. This usually involves deflection of engaging elements so that improper interface connections, leakage, and material wear or damage are likely to occur. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For the purpose of illustration, certain embodiments of the present invention will now be described with reference to the accompanying diagrammatic drawings, in which: 
         FIG. 1  illustrates a diagram of an embodiment of a fluid ejection system, in front view; 
         FIG. 2  illustrates a diagram of the embodiment of the fluid ejection system of  FIG. 1 , in side view; 
         FIG. 3  illustrates a cross sectional side view of a part of an embodiment of a fluid ejection system with a fluid cartridge in a non-connected state; 
         FIG. 4  illustrates an embodiment of a detail of a receiving structure for a fluid cartridge, in front view; 
         FIG. 5  illustrates a perspective view of an embodiment of a fluid cartridge; 
         FIG. 6  illustrates another perspective view of the embodiment of the fluid cartridge of  FIG. 5 , clearly showing a guide track and a latch track; 
         FIG. 7  illustrates a cross sectional side view of the embodiment of the part of the fluid ejection system of  FIG. 3  wherein the fluid cartridge is connected to the cartridge receiving structure; 
         FIG. 8  illustrates a flow chart of an embodiment of a method of connecting a fluid cartridge to a receiving structure; 
         FIG. 9  illustrates a flow chart a further embodiment of a method of connecting and disconnecting a fluid cartridge with respect to a receiving structure; 
         FIG. 10  illustrates a diagrammatic cross sectional bottom view of an embodiment of a fluid cartridge and a cartridge receiving structure, in a first stage of connecting the fluid cartridge, wherein the latch arrangement is made semi-transparent for reasons of illustration; 
         FIG. 11  illustrates a diagrammatic cross sectional bottom view of the embodiment of the fluid cartridge and the cartridge receiving structure of  FIG. 10 , in a second stage of connecting the fluid cartridge, wherein the latch arrangement is made semi-transparent for reasons of illustration; 
         FIG. 12  illustrates a diagrammatic cross sectional bottom view of the embodiment of the fluid cartridge and the cartridge receiving structure of  FIGS. 10 and 11 , in a third stage of connecting the fluid cartridge, wherein the latch arrangement is made semi-transparent for reasons of illustration; 
         FIG. 13  illustrates a diagrammatic cross sectional bottom view of the embodiment of the fluid cartridge and the cartridge receiving structure of  FIGS. 10-12 , in a final stage of connecting the fluid cartridge, wherein the latch arrangement is made semi-transparent for reasons of illustration; 
         FIG. 14  illustrates a diagrammatic cross sectional bottom view of the embodiment of the fluid cartridge and the cartridge receiving structure of  FIGS. 10-13 , in a first stage of disconnecting the fluid cartridge, wherein the latch arrangement is made semi-transparent for reasons of illustration; 
         FIG. 15  illustrates a diagrammatic cross sectional bottom view of the embodiment of the fluid cartridge and the cartridge receiving structure of  FIGS. 10-14 , in a second stage of disconnecting the fluid cartridge, wherein the latch arrangement is made semi-transparent for reasons of illustration. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, reference is made to the accompanying drawings. The embodiments in the description and drawings should be considered illustrative and are not to be considered as limiting to the specific embodiment or element described. Multiple embodiments may be derived from the following description and/or drawings through modification, combination or variation of certain elements. Furthermore, it may be understood that other embodiments or elements that are not literally disclosed may be derived from the description and drawings by a person skilled in the art. 
     In this description, reference may be made to a three dimensional space comprising an X, Y and Z-axis. The one dimensional insertion and ejection direction of the cartridge  3  is parallel to the Y-axis. The Y-axis is also referred to as a straight line Y. 
       FIGS. 1 and 2  show a fluid ejection system  1 . The fluid ejection system  1  comprises a fluid ejection device  2  and fluid cartridges  3 . The fluid ejection device  2  may comprise a printer. The printer may be an inkjet printer, for example a thermal inkjet, a piezo inkjet, or a continuous inkjet printer. The fluid ejection device  2  comprises one or more receiving structures  4  for receiving and exchanging one or more corresponding fluid cartridges  3 . Each cartridge  3  of the same fluid ejection device  2  may comprise a different fluid. If the fluid ejection device  2  is a printer, the fluid in each cartridge  3  may comprise ink of a specific color, for example a cyan, magenta, yellow, black and/or grey. The cartridges  3  are arranged to be exchanged with respect to the respective receiving structure  4 . 
     The receiving structures  4  are arranged to connect the cartridge  3  to the print head  5 . A fluid supply  6  is provided to receive fluid from the respective cartridges  3 , and deliver the fluid to the print head  5 . In the shown embodiment, the receiving structures  4  and the cartridges  3 , when installed, are arranged off axis. The print head  5  may comprise a page wide array print head (PWA) or a scanning print head. The receiving structure  4  is arranged to establish a fluidic interface between the cartridge  3  and the print head  5 , through the fluid supply  6 . During printing a print medium  7  extends under the print head  5 . In other embodiments (not shown), the receiving structures  4  and the cartridges  3 , when installed, are arranged on a scanning axis. In further embodiments, the cartridge  3  comprises an integrated print head, wherein the fluid volume and the print head are integrated into one cartridge supply to be connected to the receiving structure  4 . 
     The fluid ejection device  2  is provided with a control circuit  8  and a memory  9 . The fluid cartridge  3  is provided with a cartridge electrical circuit  10 , for example including a cartridge memory  11 . The control circuit  8  is arranged to retrieve data from the cartridge electrical circuit  10 . The data comprises certain cartridge characteristics, for example product characteristics, fluid type characteristics and/or fluid quantity characteristics. 
       FIG. 3  shows a receiving structure  4  and a fluid cartridge  3  in a position right before or after installation. At installation ( FIG. 7 ), all interfaces of the receiving structure  4  and the fluid cartridge  3  are interconnected. The receiving structure  4  may comprise a slot shaped opening into which the cartridge  3  is inserted. A part of the receiving structure  4  may be arranged to guide the cartridge  3  into connection with the guide  17  for movement along straight line Y. The arrow A indicates an insertion movement of the cartridge  3 , along the straight, one dimensional, line Y, represented by the Y-axis. Once the fluid cartridge  3  engages the guide  17 , it&#39;s insertion movement is substantially confined to movement along the straight line Y. In principle, there is substantially no movement along a Z and X-axis and there is substantially no rotational movement of the cartridge  3 , during insertion and ejection along the guide  17 . However, the skilled person will understand that a certain amount of play, margin or tolerance in the interfacing materials of the cartridge  3  and receiving structure  4 , such as the guide  17 , may be allowed. In one embodiment, the margin of deviation is approximately 3 millimeters or less, in a direction perpendicular to the straight line Y, and approximately 3° or less around the straight line Y, or the Z-axis or X-axis. These margins may still allow proper connection of the cartridge  3  to the receiving structure  4 . 
     The receiving structure  4  comprises two fluidic interfaces. The fluidic interfaces include one first fluid pen  12  and one second fluid pen  13 . The first fluid may be a print fluid such as ink. The second fluid may be a gas such as air. The pens  12 ,  13  are arranged to establish a fluidic connection with corresponding first and second cartridge fluidic interfaces. The first and second cartridge fluidic interface may comprise a first and second socket  14 ,  15 , respectively. The pens  12 ,  13  have central axes C 1 , C 2 , respectively, that are parallel to the Y-axis. In one embodiment (not shown), the receiving structure  4  has only one fluidic interface, for example a pen. In another embodiment (not shown), the receiving structure  4  has more than two such fluidic interfaces. 
     In an embodiment, the first fluid pen  12  comprises an ink pen. The first fluid pen  12  has a relatively small diameter at its mouth  16 . The first fluid pen  12  has a longitudinal shape. The first fluid pen  12  has a truncated, conical shape. The first fluid pen  12  may be made of molded plastics. The receiving structure  4  comprises a guide  17  for guiding the cartridge  3  along the one dimensional direction Y at insertion and ejection. The guide  17  may be longer than the first fluid pen  12 , or at least of approximately the same length, for proper insertion of the pen  12  in the corresponding socket  14 , and to prevent breaking or bending the pen  12  at insertion or ejection. This allows the pen  12  to be made of relatively cheap molded plastics. 
     In an embodiment, the second fluid pen  13  comprises a gas interface for controlling a pressure in the inner volume of the fluid cartridge  3 . The gas may comprise ambient air. In a further embodiment, the second fluid pen  13  is arranged to connect to the second socket shaped fluidic interface  15 , which in turn may connect to a pressure bag in the inner volume of the cartridge  3 . The second fluid pen  13  has a longitudinal shape. The second fluid pen  13  has a truncated, conical shape. The second fluid pen  13  may be made of molded plastics. The guide  17  may be longer than the second fluid pen  13 , or at least of approximately the same length, for proper insertion of the second fluid pen  13  in the corresponding second fluidic interface  15 , and to prevent breaking or bending the second fluid pen  13  at insertion or ejection. This allows the pen  13  to be made of relatively cheap molded plastics. 
     The guide  17  and/or the corresponding guide interface that confine the insertion and ejection movement of the cartridge  3  to one dimension. This allows relatively long and deep of the interfaces  12 ,  13  and  14 ,  15 , respectively. The respective pen  12 ,  13  may have a length of at least 5 millimeter, or at least 10 millimeters. The corresponding socket  14 ,  15  may have a depth of at least approximately 3 millimeters, or at least approximately 5 millimeters, or approximately 10 millimeters. 
     In an embodiment, the receiving structure  4  comprises a connector circuit  18  for interconnecting the control circuit  8  of the fluid ejection device  2  with the cartridge electrical circuit  19 . In  FIG. 3 , the backside of the connector circuit  18  is shown. In  FIG. 4 , an embodiment of a connector circuit  18  is shown in a plane formed by the X- and Z-axis. The connector circuit  18  comprises connector electrodes  20 . The electrodes  20  may extend along a line P approximately parallel to the Z-axis, perpendicular to the straight line Y. When the cartridge  3  is inserted or ejected along the straight line Y, the cartridge electrical circuit  19  moves along the electrodes  20  until they are connected. The connector circuit  18  is arranged to connect sideways to the cartridge electrical circuit  19 , in a direction B transverse with respect to the straight line Y. In the drawings, the transverse direction B is parallel to the X-axis. In an installed condition of the cartridge  3 , the connector circuit  18  and the cartridge electrical circuit  19  extend next to each other as seen from the direction of movement along the straight line Y. In the shown embodiment, the electrodes  20  comprise pins. The connector electrodes  20  are arranged to be moved in the transverse direction B. The electrodes  20  may comprise resilient members that are biased towards the cartridge electrical circuit  19 , for electrical connection. The electrodes  20  are pushed backwards by the cartridge electrical circuit  19  during insertion of the cartridge  3 . During insertion, the connector electrodes  20  may slide on the cartridge electrical circuit  19  until the cartridge  3  is locked in the receiving structure  4  and the electrodes  20  establish proper contact with the corresponding cartridge electrical circuit  19 . At the same time, the resilient members push the electrodes  20  against the electrical circuit  19  for better electrical connection. When the cartridge  3  is again ejected out, the electrodes  20  again move outwards due to the resilient force. 
     The fluid ejection device  2  may comprise at least two different receiving keying interfaces  22 . In an embodiment, each receiving structure  4  is provided with one specific receiving keying interface  22  that is different from the other receiving keying interfaces  22  of the other receiving structures  4 . The receiving keying interface  22  corresponds to a particular ink color, for example cyan, magenta, yellow or black. In an embodiment, the fluid ejection device  2  comprises a specific receiving keying interface  22  for each particular fluid cartridge  3 . In an embodiment, the fluid ejection device  2  comprises four receiving structure  2  with four respective receiving keying interfaces  22 , each corresponding to a fluid cartridge  3  of a specific color having a corresponding cartridge keying interface  24 . 
     The fluid ejection device  2  comprises receiving structures  4  having receiving keying interfaces  22  arranged to allow connection to a cartridge  3  with matching keying interfaces  24 , and preventing connection with fluid cartridges  3  that are arranged with non-matching cartridge keying interfaces  24 . For example, a first receiving keying interface  22  comprises a first notch  23  or cut out. A matching first cartridge keying interface  24  of a corresponding cartridge  3  comprises a corresponding inverse notch or cut out  25  that during insertion is not blocked by the first receiving keying interface  22 , but is blocked when inserted in other receiving structures with other receiving keying interfaces  22 . Likewise, the other cartridges  3  have a second, third, fourth, and/or further cartridge keying interface  24  that does not match the first receiving keying interface  22 . The other second, third, fourth and/or further receiving keying interfaces do not match the first cartridge keying interface  24 . The keying interfaces  22 ,  24  prevent that ink colors of the respective cartridge  3  and receiving structures  4  do not match. 
     The keying interface  22  of the receiving structure  4  may be arranged next to the connector circuit  18 . The corresponding keying interface  24  of the cartridge  3  may be arranged next to the cartridge electrical circuit  19 . If keying interfaces  22 ,  24  match, they may engage sideways so that the circuits  18 ,  19  may be pressed into contact. If the keying interfaces  22 ,  24  do not match, no electrical contact can be established. On the one hand, no electrical contact is made between the connector circuit  18  and the cartridge electrical circuit  19  if the keying interfaces do not match. On the other hand, a proper contact between the interconnecting circuits  18 ,  19  is aided by the respective keying interfaces  22 ,  24  of the receiving structure  4  and the cartridge  3 , respectively. 
     The guide  17  is arranged to guide the corresponding fluid cartridge  3  along the straight line Y. The guide  17  is arranged to engage a corresponding guide interface of the cartridge  3 , for example a guide track  21 . The guide  17  comprises a rail that extends parallel to the Y-axis. The guide  17  is longer than each of the pens  13 , to ensure proper alignment of the pens  12 ,  13  with the respective sockets  14 ,  15 . This may provide for a good interconnection without leakage and may prevent deformation of the pens  12 ,  13 . The guide  17  may comprise a T-rail for engaging the corresponding guide track  21  of the cartridge  3 . A T-rail prevents rotation of the cartridge  3  around the straight line of movement Y, as well as around the other axes X, Z. 
     The receiving structure  4  comprises a latch arrangement  26  for locking the cartridge  3 . In the shown embodiment, the latch arrangement  26  comprises a latch  27 , arranged to be guided by a corresponding latch track  28  of the cartridge  3 , between a locked and an unlocked position. The latch  27  may be arranged in the bottom of the receiving structure  4  for engaging the bottom  35  of the cartridge  3 . The latch arrangement  26  may comprise a latch pivot  29  and a pivot arm  29 B, to allow moving of the latch  27  between a locked and unlocked position, by pivoting around a pivot axis L. In the drawing, the pivot axis L is perpendicular to the straight line Y, parallel to the Z-axis. In an embodiment, the latch  27  is biased around the pivot axis L, so as to return to a starting position after ejection of the cartridge  3 , and so as to engage respective latch track walls. 
     In an embodiment, the latch  27  comprises a pin. In a locked position, the latch  27  engages a corresponding latch stop  30  of the cartridge  3 . In an unlocked position, the latch  27  is disengaged from the latch stop  30 , so that the cartridge  3  can be released from the receiving structure  4 . The latch  27  may extend on top of the pivot arm  29 B. In an installed condition of the cartridge  3 , the latch  27  extends in the latch track  28  while the pivot  29  and pivot arm  29 B extend below the bottom  34  of the cartridge  3 . In the shown embodiment, the latch arrangement  26  comprises latch boundaries  29 C for limiting the movement of the latch  27 . In an embodiment, the latch boundaries  29 C are arranged to engage and limit the movement of the latch pivot arm  29 B. In an inserted condition of the cartridge  3  the latch boundaries  29 C extend under the cartridge  3 . 
     The cartridge receiving structure  4  comprises an ejector  31 .  FIG. 3  shows the ejector  31  in a decompressed state, after ejection or before insertion of the cartridge  3 . Each receiving structure  4  comprises an ejector  31 . The ejector  31  is biased in a direction parallel to the straight line Y. The ejector  31  may comprise a spring, or another resilient element, for example an elastomeric element. The spring may comprise a helical spring. When the fluid cartridge  3  is inserted and latched, the leading end  44  of the ejector  31  engages the front face  33  of the cartridge  3 . In the shown embodiment, the central axis C 2  of the spring is equal to the central axis C 2  of the second fluid pen  13 . The second fluid pen  13  extends within the spring. The helical spring is attached to a base  32  of the second fluid pen  13 . The size of the ejector spring is such that in a decompressed condition of the helical spring ( FIG. 3 ), the cartridge  3  can be taken out by hand. 
     The ejector  31  is arranged to push the cartridge  3  out of the receiving structure  4 . In an installed and locked condition, the cartridge  3  is retained in the receiving structure  4  by the latch  27 , while compressing the ejector  31 . The latch  27  may be directed from a locked to an unlocked position by further pushing the cartridge  3  against the force of the compressed ejector  31  along the straight line Y, as will be explained further below. In an unlocked position, the latch  27  releases the cartridge  3 , and the ejector  31  decompresses so as to eject the cartridge  3  in a direction out of the receiving structure  4  along the straight line Y. 
       FIGS. 5 and 6  illustrate an embodiment of a fluid cartridge  3  in perspective view.  FIG. 5  clearly depicts the front face  33 , while  FIG. 6  more clearly depicts the bottom face  35 . In the shown embodiments, the fluidic, electric and keying interfaces are arranged on the front face  33 . The guide interface, latch track  28  and latch stop  30  are arranged on the bottom face  35 . 
     The fluidic interfaces of the cartridge  3  comprise a first cartridge fluidic interface for a first fluid and a second cartridge fluidic interface for a second fluid. In an embodiment, the first fluid comprises a print fluid or liquid such as ink, and the second fluid comprises a gas such as air. In the shown embodiment, the first and second cartridge fluidic interfaces comprise a first and a second socket  14 ,  15 , respectively, arranged to receive and transport fluid from and/or to respective pens  12 ,  13 , respectively. The first socket  14  may be connected to an inner volume of the cartridge  3 . The second socket  15  may be connected to a pressure bag in the inner volume of the cartridge  3 . 
     The depth of the respective socket  14 ,  15  is approximately the same as or shorter than a length of the guide  17  or guide track  21 , to receive the respective pen  12 ,  13  after engagement of the cartridge  3  with the guide  17 , to ensure proper alignment with the respective pen  12 ,  13 . The central axes C 1 , C 2  of the sockets  14 ,  15  are parallel to the straight line Y. In an installed condition of the cartridge  3 , the central axes C 1 , C 2  of the sockets  14 ,  15  are approximately the same as the central axes C 1 , C 2  of the respective receiving fluidic interfaces  12 ,  13 . 
     The cartridge  3  may comprise an ejector alignment interface  36  on the front face  33 . In an embodiment, the ejector alignment interface  36  is arranged near and/or around one of the cartridge fluidic interfaces, which in the shown embodiment are arranged as sockets  14 ,  15 . In the shown embodiment, the ejector alignment interface  36  is arranged around the second socket  15 , having the same central axis C 2  with the second socket  15 , and in an inserted condition of the cartridge  3 , the same central axis C 2  as the second pen  13 . In the shown example, the ejector alignment interface  36  comprises a ring, for example in the shape of a ridge or flange around the second socket  15 , for engaging the inner circumference of the leading end  44  of the spring shaped ejector  31 , for aligning and maintaining the ejector  31  in position when engaging the cartridge  3 . 
     The first socket  14  comprises seal ring  37  for receiving the first pen  12 . The seal ring  37  comprises resilient material, for example elastomeric material, to at least substantially fluid tightly enclose the first fluidic pen  12 , in a connected condition of the first pen  12 . As will be explained further below, at an insertion and ejection stage, the pen  12  is inserted further inwards into the first socket  14 , as compared to a position wherein the pen  12  is connected for printing. Therefore the seal ring  37  is arranged to allow further deformation, to allow such further insertion of the first pen  12 . The inner diameter of the seal ring  37  is such that it fluid tightly encloses the first pen  12  from a narrow portion of the conical shape of the pen  12  up to a wider portion. For example, the pen  12  may have a smallest diameter of approximately 2.0 and a largest diameter of approximately 2.3 millimeter along the coned shape. In other embodiments the pen  12  may have a smallest diameter of at least approximately 1.5 and/or a largest diameter of approximately 3.5 millimeter or less along the coned shape of the pen  12 . Again further embodiments may have smaller and/or larger diameters, respectively. 
     The seal ring  37  is arranged to fluid tightly enclose the first pen  12  along a substantial part of the length of the first pen  12 . In an embodiment, the inner diameter of the seal ring  37  is approximately 1.2 millimeters. Depending on the diameter of the pen  12 , in other embodiments the inner diameter of the seal ring  37  may be between approximately 0.6 and approximately 3.0 millimeters. The inner diameter of the seal ring  37  may stretch while maintaining its fluid tight pen enclosing characteristics when the pen  12  slides through the seal ring  37 , for example at least approximately 0.3 millimeters, or in another embodiment at least approximately 0.6 millimeters, or in another embodiment at least approximately 1.6 millimeters. In the shown embodiment, the seal ring  37  comprises a tapering receiving mouth  37 B for aligning the first pen  12  at insertion. In the shown embodiment, the seal ring  37  comprises bumps  37 C, arranged to prevent that the seal ring  37  sticks against an opposite engaging surface, for example at insertion in the receiving structure and/or at manufacture. 
     The cartridge  3  comprises an electrical circuit  19  ( FIG. 3 ). In the shown embodiment, the electrical circuit  19  is sunken with respect to the front face  33 , so that electrical contact with the connector circuit  18  is made only after the other interfaces are connected. In an embodiment, this may prevent that a printer receives electrical signals before the fluidic interfaces  12 ,  14 ,  13 ,  15  are connected. Such electrical signals sometimes trigger a printer to actuate a printhead  5  and/or cartridge  3 , which may be prevented by certain embodiments of this disclosure. 
     The cartridge electrical circuit  19  is arranged to connect sideways, when inserted in the receiving structure  4 . In connected condition, the connector circuit  18  extends at least partly within the cartridge  3 . For example, the cartridge electrical circuit  19  comprises electrodes  38  extending in one plane, approximately perpendicular to the front face  33  of the cartridge  3 , and parallel to the insertion direction, and/or a plane formed by the Z-axis and Y-axis. In an embodiment, the electrodes  38  of the cartridge electrical circuit  18  extend along a line PP that is approximately parallel to the Z-axis and/or the front face  33 , in an installation position of the cartridge  3 . The line PP extends behind the front face  33 . The electrodes  38  of the cartridge electrical circuit  19  are arranged to connect to the corresponding electrodes  20  of the connector circuit  18 . The line PP that extends through the electrodes  38  of the cartridge  3  is parallel to the line P ( FIG. 4 ) that extends through the electrodes  20  of the connector circuit  18 , in an installed condition of the cartridge  3 . In an installed condition, the connector circuit  38  extends at least partly through or behind the front face  33  of the cartridge  3 , for connection with the cartridge electrical circuit  18 . 
     In an embodiment, the cartridge  3  comprises a cartridge keying interface  24  for preventing connection to a receiving structure  4  that is arranged with a non-matching keying interface  22 . In the shown embodiment, the cartridge keying interface  24  comprises a cut out  25 . In other embodiments, the cartridge keying interface  24  may comprise a protrusion, and in again other embodiments it may comprise both. The cartridge keying interface  24  is arranged to block further insertion of the cartridge  3  if the receiving keying interface  22  does not match. The cartridge keying interface  24  is arranged to block insertion of the connector circuit  18  into the cartridge  3  if the receiving keying interface  22  does not match, so that electrical connection with the cartridge electrical circuit  19  will fail. 
     The keying interfaces  22 ,  24  may be arranged to provide additional alignment of the cartridge  3  with respect to the receiving structure  4 , in addition to the guide  17 , for example preventing rotation around the straight line of movement Y. Furthermore, if the keying interfaces  22 ,  24  of the receiving structure  4  and the cartridge  3  match, the keying interfaces  22 ,  23  may engage due to their corresponding shape, so that the circuits  18 ,  19  are interconnected properly. 
     In some embodiments, the cartridges  3  are not provided with a keying interface  24  so that the cartridges  3  may match any of the receiving structures  4  of the fluid injection device  1 , and the circuits  18 ,  19  interconnect, regardless of the receiving keying interface  24 . 
     The cartridge  3  comprises a guide interface for cooperation with the guide  17  of the receiving structure  4 . In the shown embodiment, the guide interface comprises a guide track  21 . The guide interface is arranged for guiding the cartridge  3  along a straight line Y for connecting the interfaces. The guide interface may have a guide engaging surface that extends parallel to said straight line Y. 
     The guide track  21  is arranged for engaging the guide  17 . The guide track  21  may be arranged to guide a corresponding T-rail guide  17 . In the shown embodiment, the guide track  21  comprises a T-shaped cut out. The guide track  21  comprises flanges  39  for engaging under the wings  17 B ( FIG. 3 ) of the T-rail guide  17 . The guide track  21  may comprise a tapered opening  40  for facilitating easy reception of the T-rail guide  17 . The flanges  39  may be tapered near the opening  40 . The guide track  21  may further comprise a guide stop  45 . 
     The bottom  35  of the cartridge  3  further comprises a latch track  28 . The guide track  21  and the latch track  28  may comprise one integral cut out in the bottom  35  of the cartridge  3 . The bottom  35  may comprise an integrally molded plastic shape. 
     The cartridge  3  comprises a latch track  28  and a latch stop  30 . The latch track  28  is arranged to move the latch  27  with respect to the latch stop  30 . Once the latch  27  engages the latch stop  30 , the cartridge  3  is retained. The position of the latch stop  30  may determine the location of the cartridge interfaces with respect to the receiving structure interfaces, along the straight line Y. 
     The latch track  21  comprises a locking track  28 A and an unlocking track  28 B. The locking track  28 A may be fully or partially different from the unlocking track  28 B. The latch stop  30  is arranged between the locking track  28 A and the unlocking track  28 B, so that the latch  27  is guided on one side  28 A of the latch stop  30  during insertion, and on an opposite side  28 B at ejection. At insertion, the latch  27  is guided by the locking track  28 A. The locking track  28 A may comprise a latch guiding surface  46  of the latch stop  30 , for guiding the latch  27  on the correct side of the latch stop  30 . The locking track  28 A may further comprise a latch guide wall  47 , at the end of the locking track  28 A. The latch guide wall  47  is arranged to receive the latch  27  at the end of the locking track  28 A, and direct the latch  27  to the latch stop  30 . The latch stop  30  comprises a latch stop wall  49  and a latch abutment  50 . The latch guide wall  47  is arranged to guide the latch  27  into an engaging locked position with the latch stop wall  49  ( FIG. 13 ). The abutment  50  comprises a protrusion in the stop wall  49  for keeping the latch  27  from sliding off the latch stop wall  49 . In the locked position, the latch  27  engages the abutment  50 . In the locked position, the ejector  31  is compressed and pushes the cartridge  3  so that the latch stop  30  is pushed against the latch  27 . 
     Furthermore, the unlocking track  28 B comprises a latch re-direct wall  48 . The latch re-direct wall  48  is arranged to receive the latch  27  when the latch stop  30  and latch track  28 A are pushed inwards, and to guide the latch  27  into the unlocking track  28 B for ejection, out of the latch stop engagement position. At ejection, the latch  27  passes the opposite side of the latch stop  30 , with respect to insertion. The latch re-direct wall  48  may be arranged at the end of the latch track  28 . Once the latch  27  is in an unlocked position, the ejector  31  ejects the cartridge  3  so that it can be taken out manually. 
     In an embodiment, the latch track  28  comprises audible and/or tactile feedback members. The latch  27  may be biased around it pivot axis L. The latch  27  may slide against latch track walls while the latch  27  travels through the latch track  28 . For example, one or more latch track walls may comprise one or more feedback members such as ledges to provide for audible and/or tactile feedback while the latch  27  travels in the latch track  28 . The feedback members may be provided near the latch guide wall  47 , from where latch  27  will move into a locked position if the cartridge  3  is released. When receiving audible and/or tactile feedback, a user may know that the cartridge  3  may be released and that it is locked to the receiving structure  4 . Another feedback member may be provided near the latch re-direct wall  48  for indicating an unlocking of the cartridge  3 . 
       FIG. 7  shows a cross section of a part of the fluid ejection system  1 , wherein the fluid cartridge  3  and the receiving structure  4  are connected. The ejector  31  is compressed and pushes the cartridge latch stop  30  against the latch  27 . The cartridge  3  is further held in place by the guide  17 . The pens  12 ,  13  extend largely within the respective sockets  14 ,  15  for transporting the respective fluids between the cartridge  3  and the fluid ejection device  2 . 
     The electrodes  20 ,  38  of the connector circuit  18  and the cartridge electrical circuit  19 , respectively, interconnect sideways. For example, the electrodes  20 ,  38  interconnect along a line P or PP that is parallel to the Z-axis, and/or in a plane that is parallel to the plane formed by the Y-axis and the Z-axis. Since the cartridge electrical circuit  19  is sunken with respect to the front face  33  of the cartridge  3 , the connector circuit  18  and the cartridge electrical circuit  19  interconnect within the outer circumference of the cartridge  3 , behind the front face  33 . In an installed condition, the connector circuit  18  extends at least partly within the cartridge  3 . In an embodiment, the connection between the connector circuit  18  and the cartridge electrical circuit  19  is established behind and/or next to a cartridge keying interface  24 , within the cartridge  3 . 
     In an embodiment, the cartridge  3  comprises at least one finger engagement surface  51  to facilitate and indicate manual handling of the cartridge  3 , for example when inserting or taking out the cartridge  3 . The finger engagement surface  51  may comprise one or a combination of an inwards curve, one or more ribs, a cut out, etc. The finger engagement surface  51  may be arranged on the top face  53  of the cartridge  3 , and close to the back face  34 . As illustrated in the shown embodiment, in an installed condition of the cartridge  3 , the receiving structure  4  largely covers the finger engagement surface  51 . After ejection, the finger engagement surface  51  is visible and free to be engaged for taking out the cartridge  3 . 
     In an embodiment, the cartridge  3  comprises a finger push surface  52  to indicate that the cartridge  3  needs to be pushed into the receiving structure  4  for both locking and unlocking of the cartridge  3 . The finger push surface  52  may comprise one or a combination of an inwards curve, one or more ribs, a cut out, etc. The finger push surface  52  is arranged in the back face  34 . In an installed condition of the cartridge  3 , the back face  34  and the finger push surface  52  are visible outside of the receiving structure  4 . Although the finger push surface  52  may have a predetermined location on the back face  34 , an aspect of certain embodiments of this disclosure is that the cartridge  3  may be pushed on any location of the back face  33  for proper connection of the interfaces, because guide  17  may guide the cartridge  3  along the straight line Y, irrespective of a specific pushing location or inclination. 
       FIG. 8  shows an embodiment of a method of connecting a fluid cartridge  3  to a receiving structure  4  in a flow chart. In a first stage  800  of such method, a fluid cartridge  3  is inserted in a receiving structure  4 . The movement is confined to one dimension, that is, the cartridge  3  is moved along the straight line Y, as indicated by stage  810 . At the end of the one dimensional movement, a fluidic connection is established between the cartridge  3  and the fluid ejection device  2 . In a stage  820 , the latch  27  is guided into the locked position by the movement along the straight line Y. The latch  27  maintains the fluidic connection. Stage  810  and  820  may occur simultaneously. In a stage  830 , fluid may flow through the connected fluidic interfaces, for example for fluid ejection. 
       FIG. 9  shows a further embodiment of a method of connecting a fluid cartridge  3  to a receiving structure  4  in a flow chart.  FIG. 10-15  illustrate sequential positions of the cartridge  3  with respect to the latch arrangement  26 , corresponding to some of the stages  900 - 914  of  FIG. 9 . 
     In a stage  900 , the cartridge  3  is manually inserted into the receiving structure  4 .  FIG. 10  corresponds to stage  900 , wherein the position of the cartridge  3  with respect to the receiving structure  4  and the latch arrangement  26  are illustrated. In a next stage  901 , the guide track  21  engages the guide  17 . By further pushing the cartridge  3  into the receiving structure  4 , the guide  17  guides the cartridge  3  along the straight line Y, in the direction of the ejector  31 . In a further stage  902 , the latch  27  engages the latch track  28 . The latch  27  is guided along the locking track  28 A, as illustrated by  FIG. 11 . The pivot arm  29 B pivots around pivot axis L ( FIG. 3 ), to allow the latch  27  to be guided by the walls of the locking track  28 A. In stage  903 , the ejector  31  engages the front face  33  of the cartridge and is compressed. The ejector  31  may engage the ring  36  that is provided around a second pen receiving socket  15 . Said stages  901 - 903  may take place simultaneously. 
     In the embodiment shown in  FIGS. 9-15 , the cartridge  3  and the receiving structure  4  have matching keying interfaces  22 ,  24 . In a stage  904 , the fluidic interfaces  12 ,  13 ,  14 ,  15  are interconnected and the keying interfaces  22 ,  24  of the receiving structure  4  and the cartridge  3  match. The matching keying interfaces  22 ,  24  allow the cartridge electrical circuit  19  and the connector circuit  18  to interconnect. After the key match, in stage  905 , the electrical connection between the circuits  18 ,  19  is established. The control circuit  8  receives a corresponding signal that the electrical connection is established. The established electrical connection implies that the fluidic connections are also established. 
     In a stage  906 , the user pushes the cartridge  3  in until receiving a tactical and/or audible feedback. For example, the latch  27  engages the end  47  of the latch track  28  and/or the guide stops  45  engage an end of the guide  17  and/or the ejector  33  cannot be compressed further. In the corresponding  FIG. 12  it is shown that the latch  27  engages the end of the latch track  28 , in this embodiment the latch  27  engages the latch guide wall  47  for directing the latch  27  in a locked position when released. In a stage  907 , the user will manually release the cartridge  3 . In a stage  908 , the ejector  31  decompresses, pushing the cartridge  33  backwards until the latch  27  engages the latch stop  30 . As can be seen from corresponding  FIG. 13 , the latch  27  retains the cartridge  3  by engaging the latch stop wall  49 . The latch  27  is held in position by the abutment  50 . The stages  904  and  905  of the key match and electrical connection, and the stages  906 - 908  of the latch lock may take place approximately simultaneously. 
     If the cartridge  3  is not pushed in correctly, the fluidic and/or other interfaces may not have been properly connected. In such case, the latch  27  may not reach the latch guide wall  47  and does not reach the locked position. Then, the cartridge  3  will automatically be pushed out by the ejector  31 , before any electrical and/or fluidic connection is made. 
     In a stage  909 , the fluid ejection system  1  prints by retrieving the first fluid from the cartridge  3 , through the first fluidic interfaces  12 ,  14 . After printing, for example when the cartridge  3  is substantially empty, the cartridge  3  may be ejected for replacement. In a stage  910 , a user pushes the cartridges  3  in the direction of the ejector  31 . By pushing the cartridge  3 , the latch  27  may engage the latch re-direct wall  48 . In a next stage  911 , the latch  27  is guided into an unlocked position, for example by the latch re-direct wall  48  ( FIG. 14 ). In the unlocked position, the cartridge  3  is no longer retained by the latch  27 . In a stage  912 , a user may manually release the cartridge  3 . In a stage  913 , the ejector  31  decompresses, ejecting the cartridge  3  ( FIG. 15 ). Ejection is made possible since the cartridge  3  is no longer retained ( FIG. 15 ). In stage  914 , the user takes the cartridge  3  out of the receiving structure  4 . 
     As described, the cartridge  3  may comprise a first fluidic interface  12 , a second fluidic interface  13 , an electrical interface  19 , an ejector alignment interface  36 , and/or a keying interface  24 , which are arranged in the front face  33 . The guide interface is arranged in the bottom face  35 , having a receiving opening  40  near the front face  33 . Hence, the interfaces are arranged to engage near the front surface  33  of the cartridge  3 . In the shown embodiment, the keying interface  24  and the electrical interface  19  are arranged near the top surface  53 , the second fluidic interface  15  and the ejector alignment interface  36  are arranged near the middle of the front surface  33 , and the first fluidic interface  14  and the guide receiving opening  40  are arranged near the bottom face  35 . The interfaces are relatively evenly distributed over the front face  33 , providing for a relatively even distribution of the connecting forces of the respective interfaces, and relatively low total connection force, for example around 14 Newton or less. In the latch and guide mechanisms of the fluid ejection system  1 , no deformation of latch or guide parts is necessary. A relatively light and simple push is sufficient for establishing a secure lock. Furthermore, the guide  17  allows for a user to push on any location of the back face  34  of the cartridge  3  for establishing all connections in one direction Y. 
     The cartridge  3  and receiving structure  4  may be relatively thin, consuming just a small volume of the printer. The cartridge motion track also consumes relatively little space because it comprises a straight line Y. Moreover, the cartridge  3  may be released using the same push motion in the same direction Y. If the cartridge  3  is not properly connected, for example fluidically and/or electrically, the cartridge  3  is automatically pushed out by the ejector  31 . 
     The above description is not intended to be exhaustive or to limit the invention to the embodiments disclosed. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In some embodiments, mechanical inversions may be applied with respect to the shown embodiments. For example, the latch track  28  may be provided on the receiving structure  4 , while the latch arrangement  26  may be provided in the cartridge  3 . The first and second fluidic interfaces of the cartridge  3  may comprise pens, while the corresponding first and second fluidic interfaces of the receiving structure  4  may comprise sockets. 
     The indefinite article “a” or “an” does not exclude a plurality, while a reference to a certain number of elements does not exclude the possibility of having more elements. A single unit may fulfill the functions of several items recited in the disclosure, and vice versa several items may fulfill the function of one unit. 
     In the following claims, the mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Multiple alternatives, equivalents, variations and combinations may be made without departing from the scope of the invention.