Abstract:
A print liquid cartridge comprising a print liquid chamber, print liquid supply portion, a stopper, and a release member. The print liquid supply portion establishes a communication between an interior of the print liquid chamber and an exterior of the print liquid chamber. The stopper prevents the printing-liquid cartridge from moving in a direction opposite to the liquid communication direction. The release member releases the stopper, such that the printing-liquid cartridge is permitted to move in a direction opposite to the fluid outflow direction. The stopper is aligned with the release member in a height direction orthogonal to the liquid communication direction and a width direction.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priorities from Japanese Patent Application No. 2011-074230 filed Mar. 30, 2011 and Japanese Patent Application No. 2011-218030 filed Sep. 30, 2011. The entire contents of these applications are incorporated herein by reference. 
       TECHNICAL FIELD 
       [0002]    The present invention relates to a printing-liquid cartridge that is mountable into and removable from a cartridge mounting portion, and to a recording apparatus having the cartridge mounting portion and printing-liquid cartridge. 
       BACKGROUND 
       [0003]    A known image recording apparatus of a so-called tube-supply system has an ink cartridge that is positioned on the outside of a carriage on which a recording head is mounted, and the ink cartridge and the recording head are connected via a tube. The ink cartridge is configured to insert horizontally into an opening of a cartridge mounting portion positioned in the front of the image recording apparatus. The cartridge may be inserted into and removed from the cartridge mounting portion. When the ink cartridge is inserted into the cartridge mounting portion, an ink channel extending from the ink cartridge to the recording head is formed. 
         [0004]    The cartridge mounting portion may include a hollow needle or the like, which is referred to as an “ink needle,” such that the ink stored in the ink cartridge is supplied to the recording head via the tube. 
         [0005]    The mounting portion may include a locking mechanism configured to retain the ink cartridge in its mounted state and a biasing member configured to bias the ink cartridge toward the opening of the cartridge mounting portion. 
         [0006]    In this manner, a reduction in size of the recording apparatus is constrained by an arrangement of the locking mechanism in the cartridge mounting portion. 
       SUMMARY 
       [0007]    In view of these and other shortcomings of the related art, it is an object of the invention to provide the smaller recording apparatus. 
         [0008]    According to an aspect of the invention, there is provided a print liquid cartridge comprising a print liquid chamber, print liquid supply portion, a stopper, and a release member. The print liquid supply portion may establish a communication between an interior of the print liquid chamber and an exterior of the print liquid chamber. The stopper may prevent the printing-liquid cartridge from moving in a direction opposite to the liquid communication direction. The release member may release the cartridge from preventing the cartridge to move in opposite direction of the liquid communication direction. The stopper may be arranged to offset from the release member in a height direction orthogonal to the fluid outflow direction and a width direction. 
         [0009]    According to another aspect of the invention, there is provided a recording apparatus is provided a cartridge mounting portion. The cartridge mounting portion receives therein a print liquid cartridge when the print liquid cartridge is inserted into the cartridge mounting portion in the fluid outflow direction. The cartridge mounting portion may comprise an engaging member which may associate with the stopper of the printing-liquid cartridge, 
         [0010]    Other objects, features, and advantages will be apparent to persons of ordinary skill in the art from the following detailed description of the invention and the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    For a more complete understanding of the present invention, needs satisfied thereby, and the objects, features, and advantages thereof, reference now is made to the following description taken in connection with the accompanying drawings. 
           [0012]      FIG. 1  is a conceptual cross-sectional view showing an internal structure of a printer provided with a cartridge mounting unit according to an embodiment of the invention; 
           [0013]      FIG. 2  is a perspective view of an ink cartridge; 
           [0014]      FIG. 3  is a vertical cross-sectional view showing an internal structure of the ink cartridge of  FIG. 2 ; 
           [0015]      FIG. 4  is a vertical cross-sectional view of a cartridge mounting unit; 
           [0016]      FIG. 5A  is a vertical cross-sectional view of the ink cartridge of  FIG. 3  mounted on the cartridge mounting unit of  FIG. 4 , illustrating a state in which the ink cartridge is initially being inserted into the cartridge mounting unit; 
           [0017]      FIG. 5B  is a vertical cross-sectional view of the ink cartridge of  FIG. 3  mounted on the cartridge mounting unit of  FIG. 4 , illustrating a state in which the ink cartridge is further being inserted into the cartridge mounting unit after the state of  FIG. 5A ; 
           [0018]      FIG. 6A  is a vertical cross-sectional view of the ink cartridge of  FIG. 3  mounted on the cartridge mounting unit of  FIG. 4 , illustrating a state in which the ink cartridge is fully mounted in the cartridge mounting unit; 
           [0019]      FIG. 6B  is a vertical cross-sectional view of the ink cartridge of  FIG. 3  mounted on the cartridge mounting unit of  FIG. 4 , illustrating a state in which the ink cartridge is initially being removed from the cartridge mounting unit; 
           [0020]      FIG. 7  is a perspective view an ink cartridge according to a first variation of the invention; 
           [0021]      FIG. 8  is a vertical cross-sectional view showing an internal structure of the ink cartridge of  FIG. 7 ; 
           [0022]      FIG. 9A  is a vertical cross-sectional view of the ink cartridge of  FIG. 7  mounted in the cartridge mounting unit of  FIG. 11 , illustrating a state in which the ink cartridge is initially being inserted into the cartridge mounting unit; 
           [0023]      FIG. 9B  is a vertical cross-sectional view of the ink cartridge of  FIG. 7  mounted in the cartridge mounting unit, illustrating a state in which the ink cartridge is further being inserted into the cartridge mounting unit after the state of  FIG. 5A ; 
           [0024]      FIG. 10A  is a vertical cross-sectional view of the ink cartridge mounted in the cartridge mounting unit, illustrating a state in which the ink cartridge is completely mounted in the cartridge mounting unit; 
           [0025]      FIG. 10B  is a vertical cross-sectional view of the ink cartridge mounted in the cartridge mounting unit, illustrating a state in which the ink cartridge is being removed from the cartridge mounting unit after the state of  FIG. 10A ; and 
           [0026]      FIG. 11  is a vertical cross-sectional view of the cartridge mounting unit according to the first variation of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    Embodiments of the present invention, and their features and advantages, may be understood by referring to  FIGS. 1-11 , like numerals being used for like corresponding parts in the various drawings. The embodiments described below are examples only, and the embodiments may be modified as needed without changing the scope of the invention. 
         [0028]    An ink cartridge  30  according to an embodiment of the present invention will be described with reference to  FIGS. 1 through 6B . 
       Overview of a Printer  10   
       [0029]    First, a printer  10  in which the ink cartridge  30  is accommodated will be described with reference to  FIG. 1 . The ink cartridge  30  corresponds to the printing-liquid cartridge. The printer  10  corresponds to the recording apparatus. The terms “upward”, “downward”, “upper”, “lower”, “above”, “below”, “beneath”, “right”, “left”, “front”, “rear” and the like will be used throughout the description assuming that the printer  10  is positioned in an orientation in which it is intended to be used. 
         [0030]    The printer  10  uses an inkjet recording system to record images by selectively ejecting ink droplets onto a recording paper. As shown in  FIG. 1 , the printer  10  may comprise an ink supply device  100 . The ink supply unit  110  may comprise a cartridge mounting unit  110 . The cartridge mounting unit  110  allows the ink cartridge  30  to be mounted therein. The cartridge mounting unit  110  includes an opening  112  which opens toward the outside on one surface of the image recording apparatus  10 . The ink cartridge  30  may be configured to be inserted into the cartridge mounting unit  110  and removed from the cartridge mounting unit  110  through the opening  112 . The ink cartridge  30  is inserted into or removed from the cartridge mounting unit  110  through the opening  112 . 
         [0031]    Ink is stored in the ink cartridge. A recording head  21  may connect to the ink cartridge  30  via an ink tube  20 . The recording head  21  may have a sub-tank  28  in which temporarily stores ink supplied through the ink tube  20 . The recording head  21  may include a plurality of nozzles  29  through which ink supplied from the sub-tank  28  may selectively eject to form a recording image. 
         [0032]    The printer  10  also may comprise a paper tray  15 , a sheet supply roller  23 , a sheet passage  24 , a pair of transfer rollers  25 , a platen  26 , a pair of discharge roller  22 , and a paper discharge tray  16  arranged in this order along a feed direction. The sheet supply roller  23  may supply the sheet from the paper feed tray  15  to the sheet passage  24 ; and the pair of transfer rollers  25  may further convey the sheet to the platen  26 . Then, the recording head  21  may selectively eject the ink onto the sheet passing through the platen  26  to form an image on the sheet. The pair of discharge rollers  22  then may discharge the sheet onto the discharge tray  16 . 
         [0033]    Note that the general structure of the printer  10  according to the preferred embodiment is merely one example. Obviously the printer  10  may employ other constructions used in inkjet printers known in the art, such as different methods for feeding and conveying the recording paper and a different shape for the conveying path. 
       Ink Supply Device  100   
       [0034]    As shown in  FIG. 1 , the ink supply device  100  is provided in the printer  10 . The ink supply device  100  functions to supply ink to the recording head  21  provided in the printer  10 . The ink supply device  100  includes the cartridge mounting unit  110  in which the ink cartridge  30  may be inserted.  FIG. 1  shows the cartridge mounting unit  110  when the ink cartridge  30  is mounted therein. 
       Ink Cartridge  30   
       [0035]    Next, a detailed configuration of the ink cartridge  30  will be described. As shown in  FIG. 3 , the ink cartridge  30  defines therein an ink chamber  36  in which the ink is stored. As shown in  FIGS. 2 and 3 , the ink cartridge  30  has a casing  31  defining an outer shell of the ink cartridge  30 . The ink chamber  36  may be defined inside the casing  31 , or may be defined by a member separate from the casing  31  but inside the casing  31 . The ink chamber  36  corresponds to the print liquid chamber. The casing  31  corresponds to the body and the casing. 
         [0036]    The ink cartridge  30  may be configured to be installed in and removed from the cartridge mounting unit  110  in an upright position shown in  FIG. 2 , i.e. along a direction indicated by an arrow  53  with a lower surface in the drawing as a bottom surface and an upper surface in the drawing as an upper surface (hereinafter, referred to as an “insertion and removal directions  53 ”). Hereinafter, a description will be given assuming that the ink cartridge  30  is in the upright position. 
         [0037]    As shown in  FIG. 2 , the casing  31  may have a generally flat, rectangular shape with a widthwise in a direction indicated by an arrow  51  (herein after, referred to as a widthwise direction or a horizontal direction), a height in a direction indicated by an arrow  52  that is perpendicular to the widthwise direction  51  (hereinafter, referred to as a vertical direction or a height direction) and a depth in a direction indicated by an arrow  53  that is perpendicular to the vertical direction and widthwise direction  51  (hereinafter, referred to as a depthwise direction  53 ). The height of casing  31  and the depth of casing  31  are each greater than the width of casing  31 . In other words, in the upright position, the depthwise direction  53  is parallel to the insertion direction  56  and the removal direction  55 , while the widthwise direction  51  and height direction  52  are respectively orthogonal to the insertion direction  56  and the removal direction  55 . 
         [0038]    As shown in  FIG. 2 , the casing  31  may have a front wall  40 , a rear wall  42 , a pair of side walls  37 ,  38 , a top wall  39 , and a bottom wall  41 . The front wall  40  is positioned at the front side of the printer  10  when the ink cartridge  30  is inserted into the cartridge mounting unit  110 , and the rear wall  42  of the ink cartridge  30  is inserted into the cartridge mounting unit  110 , and the rear wall  42  of the casing  31  is positioned on the rear side of the casing  31 . The front wall  40  and rear wall  42  may be positioned opposite to each other in the depthwise direction  53  (in the insertion direction  56 ). Four walls may separate the front wall  40  from the rear wall  42 : a pair of side walls (not depicted) extending in the insertion and removal directions  50 , an upper wall  39  connecting the upper edges of the side walls, and a lower wall  41  also connecting the lower edges of the side walls. The upper wall  39  and lower wall  41  are spaced away from each other by a prescribed distance in the height direction  52 . The front wall  40  corresponds to the front side. The rear wall  42  corresponds to the rear side. The top wall  39  corresponds to the upper side of the present invention. 
         [0039]    An ink supply portion  43  may be positioned on the front side of the ink cartridge  30 , e.g., the front wall  40  of the casing  31  at a lower end. The ink supply portion  43  may have cylindrical outer shape, and ink supply portion  43  may project frontward from the front wall  40  in the insertion direction  56  (i.e., in the depthwise direction  53 ). The ink supply portion  43  may have an outer end portion  72  on which an ink supply outlet  71  is formed to provide external communication with the casing  31 . 
         [0040]    As shown in  FIG. 3 , an ink channel  44  may be formed to extend from the ink supply outlet  71  through an internal space of the ink supply portion  43  to the ink chamber in the depthwise direction  53 . The ink supply portion  43  corresponds to the print liquid supply portion. 
         [0041]    As shown in  FIG. 3 , within the ink supply portion  43 , a valve  70  may be configured to be opened or closed by the ink supply outlet  71 . The valve  70  may move within the ink channel  44  of the ink supply portion  43  in the depthwise direction  53  (in the insertion direction  56  as well as in the removal direction  55 ). A coil spring  73  may be provided for biasing the valve  70  toward the ink supply outlet  71 . When no external forces may be applied to the valve  70 , the coil spring  73  holds the valve  70  in a closed position for tightly sealing the ink supply outlet  71 . A portion of the outer end portion  72  of the ink supply portion  43  surrounding the ink supply outlet  71  is formed of an elastic member, such as rubber. The elastic member elastically may deform when contacted by the valve  70  biased by the coil spring  73 , tightly sealing the ink supply outlet  71 . In this state, part of the valve  70  may be exposed through the ink supply outlet  71  outside of the ink supply portion  43 , i.e., outside the ink cartridge  30 . The ink supply portion  71  is not limited to a configuration in which the ink supply valve  70  opens and closes the ink supply portion  70 . For example, a configuration in which a film, rubber stopper, or the like closes the ink supply outlet  70  when the ink cartridge inserted into the cartridge mounting unit  110 . 
         [0042]    An ink needle  122  (described later) may be also positioned on the cartridge mounting unit  110 . When the ink cartridge  30  is mounted in the cartridge mounting unit  110 , the ink needle  122  is inserted into the ink supply outlet  71 , elastically deforming the coil spring  73  and moving the valve  70  against the biasing force of the coil spring  73  into an open position separated from the ink supply outlet  71  (see  FIG. 6A ). In this state, the ink supply outlet  71  is open and ink in the ink chamber  36  can flow into the ink needle  122  through the ink channel  44 . 
         [0043]    An air introducing unit (not shown) may also be provided in the casing  31 . Accordingly, air is introduced into the ink chamber  36  via the air introducing unit as ink flows from the ink chamber  36  into the ink needle  122 . However, the air introducing unit is not an essential component. For example, the ink chamber  36  may be configured of an ink bag whose volume decreases as the amount of ink in the ink chamber  36  decreases. 
         [0044]    As shown in  FIGS. 2 and 3 , a protrusion  32  may be positioned on the lower wall  41  (a lower end of the front wall  40  below the ink supply portion  43 ). The protrusion  32  may protrude frontward in the insertion direction  56  and may have a protruding length greater than that of the ink supply portion  43  in the insertion direction  56 . 
         [0045]    As shown in  FIGS. 2 and 3 , the top wall  39  of the casing  31  may be formed with an engaging recess  45  extending from a position substantially center of the top wall  39  to the rear wall  42  in the depthwise direction  53 . The engaging recess  45  may be defined by a vertical engaging surface  46  at the front end in the insertion direction  56 , and a pair of ribs  45   a,    45   b.  That is, the engaging surface  46  may occupy a plane extending in the widthwise direction  51  and the height direction  52 . When the ink cartridge  30  is mounted in the cartridge mounting unit  110 , an engaging member  145  of the cartridge mounting unit  110  (described later) may engage the engaging surface  46 . Specifically, the engaging member  145  engages the top end of the engaging surface  46 . The top end of the engaging surface  46  corresponds to the stopper. 
         [0046]    As shown in  FIGS. 2 and 3 , a portion of the upper wall  39  that may be positioned frontward of the engaging recess  45  in the insertion direction  56  serves as a upper surface  47  that may contact the engaging member  145  of the cartridge mounting unit  110  when the ink cartridge  30  is inserted into the cartridge mounting unit  110 . That is, the upper surface  47  may have a plane extending in the widthwise direction  51  and the depthwise direction  53 . The top surface  47  and front wall  40  may be linked by a sloped surface  48  sloping relative to the top surface  47  and front wall  40 . The sloped surface  48  serves to guide the engaging member  145  onto the top surface  47 . However, the sloped surface  48  may be omitted from this construction. Alternatively, a protrusion similar to the protrusion  32  that protrudes in the insertion direction  56  may be provided in place of the sloped surface  48 . 
         [0047]    As shown in  FIGS. 2 and 3 , a pivotal member  60  is provided in the engaging recess  45 . The pivotal member  60  has a bent plate shape and extends in the depthwise direction  53 . Specifically, the pivotal member  60  has a first arm  61 , a second arm  62 , and a shaft  63  extending in the widthwise direction  51 . The shaft  63  is pivotal-movably supported by the top wall  39  at the rearward of the engaging surface  46 . The first arm  61  radially may extend from the shaft  63  frontward at the vicinity of or on the engaging surface  46 . The second arm  62  also radially may extend rearward from the shaft  63  over the rear wall  42 . With this construction, the pivotal member  60  may be pivotally moved about the shaft  63 . Note that the casing  31  and the pivotal member  60  may be integrally formed. The pivotal member  60  corresponds to the release member and the lever. 
         [0048]    While an external force (described later) may be not being applied to the pivotal member  60 , the first arm  61  may contact a bottom surface  49  of the engaging recess  45  due to its self-weight or a biasing force of a biasing member, e.g., coil spring (not shown). On the other hands, when the second arm  62  may be pushed downward against the weight or the biasing force, the pivotal member  60  may pivot about the shaft  63  in a counterclockwise direction in  FIG. 3 , thereby the first arm  61  is moved away from the bottom surface  49 . 
       Cartridge Mounting Unit  110   
       [0049]    As shown in  FIG. 4 , the cartridge mounting unit  110  may have a case  101  forming its box-like outer shell. The case  101  has an opening  112 . The ink cartridge  30  may be inserted into or removed from the case  101  through the opening  112 . The case  101  may be capable of accommodating a plurality of the ink cartridge  30 , e.g. four ink cartridges  30  corresponding to the colors cyan, magenta, yellow, and black. However, in the drawings, the cartridge mounting unit  110  is illustrated such that the case  101  can accommodate only one ink cartridge  30 . 
         [0050]    The case  101  may have an end surface  102  that faces an internal space of the case  101  and may be positioned on the opposite side of this internal space from the opening  112  in the insertion direction  56 . As shown in  FIG. 4 , a connector  103  may be positioned at a lower portion of a side wall constituting the case  101  on which the end surface  102  is formed. If the case  101  accommodates a plurality of ink cartridges  30 , a plurality of connectors  103  may be positioned. 
         [0051]    The connector  103  may include the ink needle  122  and a retaining part  121 . While not illustrated in  FIG. 4 , the ink needle  122  may be connected to the ink tube  20  on an outer surface of the side wall that has the end surface  102 . The ink tube  20  connected to each ink needle  122  is also connected to the recording head  21  of the printer  10  and is capable of delivering ink thereto. 
         [0052]    The retaining part  121  may be formed in the end surface  102  of the case  101  by hollowing out a portion of the end surface  102  in a cylindrical shape. The ink needle  122  may be coaxially disposed at the retaining part  121  and may penetrate through the side wall of case  101  having the end surface  102  in the insertion direction  56 . When the ink cartridge  30  may be mounted in the cartridge mounting unit  110 , as illustrated in  FIG. 6A , the cylindrically-shaped ink supply portion  43  may be hermetically inserted into the cylindrically-shaped retaining part  121 . At this time, the outer circumferential surface of the ink supply portion  43  may tightly contact and cohere with the surface defining the retaining part  121 . When the ink supply portion  43  is inserted into the retaining part  121 , the ink needle  122  is also inserted into the ink supply outlet  71  formed in the ink supply portion  43 . The ink needle  122  inserted through the ink supply outlet  71  moves the valve  70  from its closed position to its open position against the biasing force of the coil spring  73 . Accordingly, ink stored in the ink chamber  36  may now flow outward. The ink flowing out of the ink chamber  36  may flow into the ink needle  122  due to head difference and the like and is delivered to the recording head  21  via the ink tube  20 . 
         [0053]    As shown in  FIG. 4 , the engaging member  145  may be positioned on the case  101 . The engaging member  145  may hold the ink cartridge  30  in its mounted state in the cartridge mounting unit  110 . The engaging member  145  may be located at a position above the opening  112  formed in the case  101 . The engaging member  145  corresponds to the engaging member. 
         [0054]    The engaging member  145  may be pivotably supported to the case  101  by a support shaft  147 . The support shaft  147  may be provided at one end of the engaging member  145  nearest the opening  112  and may be mounted on the case  101 . With this construction, the engaging member  145  may be pivotably supported above and in proximity to the opening  112  of the case  101  and pivots about the support shaft  147  so as to approach or separate from the opening  112 . The engaging end  146  may be formed on another end of the engaging member  145  opposite the support shaft  147 . The engaging end  146  may be engageable with the engaging surface  46  of the engaging recess  45  formed in the ink cartridge  30 . By engaging with the engaging surface  46 , the engaging end  146  may hold the ink cartridge  30  in its mounted position relative to the case  101  against a biasing force (described later) applied from the case  101 . A position of the engaging member  145  when the engaging end  146  is engaged with the engaging surface  46  (see  FIG. 6A ) will be referred to as a “locked position,” while another position of the engaging member  145  when the engaging end  146  is not engaged in the engaging surface  46  (see  FIG. 6B ) will be referred to as an “unlocked position.” 
         [0055]    The engaging end  146  may be biased downward due to one&#39;s own weight or a biasing force of a coil spring (not shown) to contact the first arm  61  at the locked position. However, when the first arm  61  is pivotally moved upward, the engaging member  145  is also pivotally moved upward about the support shaft  147 , moving from the locked position to the unlocked position. Further, while not illustrated in the drawings, the pivoting range of the engaging member  145  may be restricted so that the engaging member  145  cannot move farther downward than the locked position (the state shown in  FIG. 4 ). Note that, the engaging member  145  is not necessary biased downward. The engaging member  145  may pivotally move downward due to its self-weight even without being biased to realize its engagement with the engaging surface  46  of the ink cartridge  30 . 
         [0056]    As shown in  FIG. 4 , the interior space of the cartridge mounting unit  110  may be expanded in the insertion direction  56  beneath the end surface  102 . Within this expanded space, a slide member  123  may be movably provided. The slide member  123  may be slidable in the insertion direction  56  and the removal direction  55  (horizontally). The slide member  123  may be generally rectangular parallelepiped in shape. The slide member  123  may have a top surface from which a protruding piece  124  protrudes upward. The protruding piece  124  may stand in an insertion path of the protrusion  32  provided on the ink cartridge  30  so that the protrusion  32  may be abuttable on the protruding piece  124  while the ink cartridge  30  is mounted in the cartridge mounting unit  110 . 
         [0057]    The expanded space in which the slide member  123  may be accommodated is defined by an end surface  125  and a front surface  127  opposing each other in the insertion direction  56 . The slide member  123  may be interposed between the end surface  125  and the front surface  127 . A coil spring  126  may be positioned in a compressed state between the end surface  125  and slide member  123  and biases the slide member  123  in the removal direction  55 . When an external force may be not applied to the slide member  123 , the slide member  123  may be placed in contact with the front surface  127  by the biasing force of the coil spring  126 . The front surface  127  may restrict the range of movement of the slide member  123  away from the end surface  125 . When the ink cartridge  30  is inserted farther into the cartridge mounting unit  110  after the protrusion  32  of the ink cartridge  30  contacts the protruding piece  124 , the slide member  123  may move together with the protruding piece  124  toward the end surface  125 , compressing the coil spring  126 . 
         [0058]    It should be noted that the protrusion  32  may not be provided at the ink cartridge  30 . Without the protrusion  32 , the ink cartridge  30  may still be applied with a biasing force acting in the removal direction  55  during the mounting process of the ink cartridge  30  into the cartridge mounting unit  110 , since the ink cartridge  30  is provided with the coil spring  73  disposed within the ink supply portion  43 . 
       Mounting the Ink Cartridge  
       [0059]    Next, operations for mounting the ink cartridge  30  in and removing the ink cartridge  30  from the cartridge mounting unit  110  will be described with reference to  FIGS. 5A through 6B . 
         [0060]    As shown in  FIG. 5A , the ink cartridge  30  may be inserted into the cartridge mounting unit  110  through the opening  112 , leading with the front wall  40  side of the ink cartridge  30 . When the ink cartridge  30  is inserted into the cartridge mounting unit  110 , the sloped surface  48  of the casing  31  contacts the engaging member  145 . As the ink cartridge  30  is farther inserted into the cartridge mounting unit  110 , the engaging member  145  slides up the sloped surface  48  onto the upper surface  47 . Accordingly, the engaging member  145  may pivot counterclockwise in  FIG. 5A , moving from the locked position to the unlocked position. 
         [0061]    As the ink cartridge  30  is mounted into the cartridge mounting unit  110 , the ink supply portion  43  may contact the retaining part  121 , and the ink needle  122  may be inserted into the ink supply outlet  71  of the ink supply portion  43 , as illustrated in  FIG. 5B . At this time, the engaging member  145  is not yet engaged in the engaging recess  45  of the casing  31 . The ink needle  122  may be inserted into the ink supply outlet  71  to contact the valve  70 . As the ink cartridge  30  may move farther in the insertion direction  56 , the valve  70  is pressed by the ink needle  122 , moving from its closed position to its open position against the biasing force of the coil spring  73 , as illustrated in  FIG. 6A . After the ink supply portion  43  is inserted into the retaining part  121  and the ink needle  122  is further inserted into the ink supply outlet  71 , the ink cartridge  30  may be mounted in its prescribed position relative to the cartridge mounting unit  110  (mounted position). While not shown in the drawings, an ink inlet is formed on a distal end of the ink needle  122 . Accordingly, ink in the ink chamber  36  may flow through the ink channel  44  and into the ink needle  122  via this ink inlet. 
         [0062]    When the ink cartridge  30  reaches its mounted position shown in  FIG. 6A , the engaging surface  46  formed on the engaging recess  45  of the casing  31  has passed the engaging end  146  of the engaging member  145  in the insertion direction  56 . Consequently, since the engaging end  146  of the engaging member  145  is no longer supported on the top surface  47  of the casing  31 , the engaging member  145  may pivot clockwise in  FIG. 6A  into the engaging recess  45 , with the engaging end  146  of the engaging member  145  contacting the engaging surface  46 . The engaging member  145  may engage in the engaging surface  46  holds the ink cartridge  30  in its mounted position against the biasing forces of the coil spring  73  and coil spring  126 . In this state, the top end of the engaging surface  46  is arranged to offset from the first arm  61  in the height direction  52 . This completes the operation for mounting the ink cartridge  30  in the cartridge mounting unit  110 . 
         [0063]    Note that the external force created by the coil spring  126  acts on the protrusion  32  provided on the front wall  40  side of the casing  31 . In place of the coil spring  73  used for opening and closing the valve  70 , a coil spring may be provided on an outside of the casing  31  as the external force. This coil spring may be positioned such that its distal end may contact the end surface  102  of the cartridge mounting unit  110 , a photosensor, or the like, and biases the ink cartridge  30  in the removal direction  55 . 
         [0064]    In a state where the ink cartridge  30  has been mounted in the cartridge mounting unit  110 , the first arm  61  of the pivotal member  60  may be positioned below the engaging end  146  of the engaging member  145 , and the second aim  62  of the pivotal member  60  may be apart from the bottom surface  49  of the engaging recess  45  and positioned above the top wall  39  of the casing  31 . 
         [0065]    When the ink in the ink chamber  36  of the ink cartridge  30  becomes depleted, the user removes the spent ink cartridge  30  from the cartridge mounting unit  110  and mounts a new ink cartridge  30 . 
         [0066]    To remove the ink cartridge  30  from the cartridge mounting unit  110 , the user presses the second arm  62  of the pivotal member  60  downward. Since the second arm  62  of the pivotal member  60  is positioned at a downstream of the rear wall  42  in the removal direction  55 , the user can operate the pivotal member  60  from the rear wall  42  side of the ink cartridge  30 . When the user presses the second arm  62  of the pivotal member  60  downward, the first arm  61  is moved upward to separate from the bottom surface  49  of the engaging recess  45 , as illustrated in  FIG. 6B . By the movement of the first arm  61  upward, the engaging member  145  may be pushed upward. Through this operation, the engaging member  145  may pivot counterclockwise in  FIG. 6B  until the engaging end  146  separates from the engaging surface  46 . That is, the engaging member  145  may pivotally move from the locked position to the unlocked position, releasing its hold on the ink cartridge  30 . 
         [0067]    When the engaging end  146  of the engaging member  145  separates from the engaging surface  46 , the external forces applied to the casing  31  (specifically, the biasing forces of the coil spring  73  and/or coil spring  126 ) move the casing  31  in the removal direction  55 . However, at this time, the pivotal member  60  is touched by the user. Accordingly, the user&#39;s hand absorbs the biasing forces of the coil springs  73  and  126  through the biasing force or its self-weight and pivotal member  60 . 
       Effects of the Embodiment  
       [0068]    When the user pivots the pivotal member  60 , the engagement between the engaging member  145  and the engaging surface  46  is released and the ink cartridge  30  may be moved in the removal direction  55  due to the external force, e.g., the biasing force of the coil spring  73  or  126 . However, in the embodiment, the pivotal member  60  for disengaging the engagement between the engaging surface  46  and the engaging member  145  is disposed not at the cartridge mounting unit  110  but at the ink cartridge  30 . Therefore, the pivotal member  60  (second arm  62 ) is contacted by the user&#39;s hand when the ink cartridge  30  moves in the removal direction  55 , and the user&#39;s hand reduces the speed of the ink cartridge  30 . As the result, the ink cartridge  30  can be prevented from falling through the opening of the printer  10  when removed from the cartridge mounting unit  110 , thereby ink can be prevented from dripping out of the ink needle  122  when the ink cartridge  30  is replaced. 
         [0069]    Further, a user-operated member for operating the engaging member  145  need not be provided in the cartridge mounting unit  110 , making it possible to produce a more compact printer  10 . 
         [0070]    Further, the second arm  62  is positioned at a downstream of the first arm  61  in the removal direction  55 . Therefore, a user can easily identify whether or not the engaging surface  46  and the engaging member  145  are engaged with each other based on the position of the second arm  62 . 
         [0071]    The engagement between the ink cartridge  30  and the cartridge mounting unit  110  is performed by the engaging surface  46  and the engaging member  145 . The pivotal member  60  is used only to release the engagement between the engaging surface  46  and the engaging member  145 . In other words, the pivotal member  60  is separately provided from the engaging surface  46 . Therefore, even if the pivotal member  60  is deformed, the engagement between the engaging surface  46  and the engaging member  145  is held. 
       Variations of the Embodiments  
       [0072]    While the invention has been described in detail with reference to the embodiments thereof, it would be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention. 
         [0073]    For example, as shown in  FIGS. 7 and 8 , the pair of ribs  45   a,    45   b  may extend in the removal direction  55  from the engaging surface  46  to around the shaft  63 . 
         [0074]    Further, as shown in FIGS.  8  and  9 (A)- 10 (B), it is preferable that a tip end of the first arm  61  does not protrude beyond the pair of ribs  45   a,    45   b.    
         [0075]    Further, as shown in  FIGS. 7-10(B) , the second arm  62  of the pivotal member  60  may be provided with a bent part  62   a  hat is bent downward. The thickness of the second arm  62  (especially, the bent part  62   a ) is greater than the thickness of the first arm  61  to provide a high rigidity. 
         [0076]    Further, as shown in  FIG. 11 , the case  101  may be formed with a first guide groove  108  and a second guide groove  109 . The first guide groove  108  extending in the removal direction  55  and insertion direction  56  is formed on the top surface of the case  101 , and the second guide groove  109  extending in the removal direction  55  and insertion direction  56  is formed on the bottom surface of the case  101 . The pair of ribs  45   a,    45   b  is guided by the guide groove  108  of the case  101  when the ink cartridge  30  is mounted in the cartridge mounting portion  110 . The ink cartridge  30  is guided in the insertion direction  56  by the first guide groove  108  and the pair of the ribs  45   a,    45   b . Note that the bottom surface  41  of the casing  31  is guided by the guide groove  109  of the case  101 . 
         [0077]    Further, an engaging member movable in the upper-lower direction may be used instead of the engaging member  145 . 
         [0078]    Further, the pivotal member  60  may move the engaging member  145  not directly but via an another member. 
         [0079]    In the embodiments described above, the coil springs  73  and  126  apply an external force in the removal direction  55  to the ink cartridge  30  when the ink cartridge  30  is mounted in the cartridge mounting unit  110 . In place of the coil springs  73  and  126 , a biasing member provided on the ink cartridge  30  may function to apply an external force to the ink cartridge  30  in its mounted state. For example, a coil spring extending in the insertion direction  56  may be provided on the front wall  40  of the casing  31 . When the ink cartridge  30  is mounted in the cartridge mounting unit  110 , the coil spring contacts the end surface  102  of the case  101  and compresses to apply an external force to the casing  31  in the removal direction  55 . 
         [0080]    In the embodiments, a detecting portion configured to detect the amount of residual ink in the ink cartridge  30  has been omitted, such a detecting portion may be provided on the ink cartridge  30 . The detection portion may be provided on the middle of the front wall  40  of the ink cartridge  30  and protrudes from the front wall  40  in a direction away from the ink chamber  36 . The detection portion is formed of a light transmissive resin. The amount of ink in the ink chamber  36  of the ink cartridge  30  may be detected manually by looking into the ink chamber  36  through the detection portion or automatically with a photo sensor. When using a photosensor, the distance between a pair of side walls constituting the detection portion is set smaller than the gap between the light-emitting element and light-receiving element of the photosensor. A light-shielding plate that moves based on the quantity of ink may be provided in the detection portion. Alternatively, the light-shielding plate may be replaced with a device capable of reducing the amount of light that reaches the light-receiving element by reflecting, diffracting, or attenuating all or a portion of the light emitted from the light-emitting element based on the amount of ink in the ink chamber  36 . 
         [0081]    While the preferred embodiments describe the printing liquid as ink stored in the ink cartridge  30  for use with an inkjet-type printer  10 , the printing liquid is not limited to ink. The present invention may also be applied to a cartridge that stores toner as the printing liquid for use in an electrophotographic image-forming apparatus, for example.