Patent Publication Number: US-8534813-B2

Title: Sets of ink cartridges

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application claims priority to and the benefit of European Patent Application No. 10 166 374.8, which was filed on Jun. 17, 2010, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to sets of ink cartridges configured to mount into a cartridge mounting portion of a recording apparatus. 
     2. Description of Related Art 
     A known tube-supply-type inkjet recording apparatus, such as an inkjet recording apparatus, as described in Patent No. EP 2 039 521 B1, has a recording head mounted on a carriage, and an ink cartridge positioned outside of the carriage and in fluid communication with the recording head via a tube. The inkjet recording apparatus has a cartridge mounting portion having an opening at a front face of a housing of the inkjet recording apparatus. The ink cartridge is configured to be inserted horizontally into the cartridge mounting portion via the opening to be mounted removably to the cartridge mounting portion. When the ink cartridge is mounted to the cartridge mounting portion, an ink path is formed from the ink cartridge to the recording head so that ink may flow therethrough. Thus, ink is supplied from the ink cartridge to the recording head via the ink path. 
     A known inkjet recording apparatus for personal use is configured to receive a small-capacity ink cartridge therein. Such a personal inkjet recording apparatus has a reduced physical size. A known inkjet recording apparatus for business use is configured to receive a large-capacity ink cartridge. Such a business, inkjet recording apparatus has an enlarged physical size, as described in Patent No. EP 1 772 274 B1. When the cartridge mounting portion is shared between the inkjet recording apparatus for personal use and the inkjet recording apparatus for business use, the cartridge mounting portion of the inkjet recording apparatus for personal use has a free space or gap, i.e., non-utilized space, formed therein, which prevents the reduction of the physical size of the inkjet recording apparatus for personal use, especially, in its width direction. 
     SUMMARY OF THE INVENTION 
     Therefore, a need has arisen for sets of ink cartridges which overcome these and other shortcomings of the related art. A technical advantage of the present invention is that the physical size of a recording apparatus may be reduced in a width direction. Another technical advantage of the present invention is that an appearance of an ink cartridge may indicate a type of the ink cartridge, e.g., an ink capacity of the ink cartridge. These technical advantages may be independent of each other, and at least one of the technical advantages may be achieved by the present invention. 
     According to an aspect of the present invention, a set of ink cartridges is configured to be mounted in a cartridge mounting portion of a recording apparatus in an insertion direction. The set of ink cartridges comprises a first ink cartridge and a second ink cartridge, and each ink cartridge of the set of ink cartridges comprises a main body and a particular protrusion positioned adjacent to a bottom wall of the main body and extending from a portion of the main body in the insertion direction away from an ink chamber. The main body comprises a first wall, the ink chamber configured to store ink therein, a communication portion disposed at the first wall and configured to place an interior of the ink chamber into fluid communication with an exterior of the ink chamber; a second wall disposed opposite the first wall, and the bottom wall. The ink chamber is disposed between the first wall and the second wall. A first length difference between a first length of a portion of the bottom wall extending from a rear end of the bottom wall of the first ink cartridge to an end of the particular protrusion of the first ink cartridge in the insertion direction and a total length of the first ink cartridge in the insertion direction is different from a second length difference between a second length extending from a rear end of the bottom wall of the second ink cartridge to an end of the particular protrusion of the second ink cartridge in the insertion direction and a total length of the second ink cartridge in the insertion direction. 
     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 
       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 drawing. 
         FIG. 1  is a schematic, cross-sectional view of a printer comprising an ink supply device. 
         FIG. 2  is a perspective view of a first cartridge, according to an embodiment of the present invention. 
         FIG. 3  is a side view of the first cartridge of  FIG. 2 . 
         FIG. 4  is a partially cutaway, side view of the first cartridge of  FIG. 2 . 
         FIG. 5  is a perspective view of a second cartridge, according to an embodiment of the present invention. 
         FIG. 6  is a side view of the second cartridge of  FIG. 5 . 
         FIG. 7  is a partially cutaway, side view of the second cartridge of  FIG. 5 . 
         FIG. 8  is a side view of the first cartridge of  FIG. 2  and a cross-sectional view of a cartridge mounting portion, in which the first cartridge is mounted to the cartridge mounting portion according to an embodiment of the present invention. 
         FIG. 9  is a side view of the first cartridge and a cross-sectional view of the cartridge mounting portion of  FIG. 8 , in which the first cartridge is disengaged from the cartridge mounting portion. 
         FIG. 10  is a side view of the first cartridge and a cross-sectional view of the cartridge mounting portion of  FIG. 8 , in which the first cartridge is further disengaged from the cartridge mounting portion. 
         FIG. 11  is a side view of the second cartridge of  FIG. 5  and a cross-sectional view of the cartridge mounting portion of  FIG. 8 , in which the second cartridge is mounted to the cartridge mounting portion. 
         FIG. 12  is a side view of the second cartridge of  FIG. 5  and a cross-sectional view of the cartridge mounting portion of  FIG. 8 , in which the second cartridge is disengaged from the cartridge mounting portion. 
         FIG. 13  is a side view of the second cartridge of  FIG. 5  and a cross-sectional view of the cartridge mounting portion of  FIG. 8 , in which the second cartridge is further disengaged from the cartridge mounting portion. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
     Embodiments of the present invention, and their features and advantages, may be understood by referring to  FIGS. 1-13 , like numerals being used for like corresponding parts in the various drawings. 
     Referring to  FIG. 1 , a recording apparatus, e.g., printer  10 , may be configured to record an image by selectively ejecting ink droplets onto a recording sheet. Printer  10  may comprise a recording head  21  and an ink supply device  100  configured to supply ink to recording head  21 . Ink supply device  100  may comprise a cartridge mounting portion  110 . Cartridge mounting portion  110  may be configured, such that a first cartridge  30  and a second cartridge  60  are selectively and removably mounted to cartridge mounting portion  110 . First cartridge  30  may have a greater capacity than second cartridge  60 , e.g., the initial amount of ink stored in first cartridge  30  may be greater than the initial amount of ink stored in second cartridge  60 .  FIG. 1  shows first cartridge  30  as it is mounted to cartridge mounting portion  110 . Cartridge mounting portion  110  may have an opening  112  formed therethrough. First and second cartridges  30 ,  60  may be inserted into or removed from cartridge mounting portion  110 , e.g., through opening  112 . Ink supply device  100  may comprise a plurality of cartridge mounting portions  110 , such that cartridges  30 ,  60  may be mounted to adjacent cartridge mounting portions  110 , e.g., in a side by side position. 
     First and second cartridges  30 ,  60  may be configured to store ink for use in a printer, e.g., printer  10 . When first cartridge  30  or second cartridge  60  is mounted to cartridge mounting portion  110 , the mounted first cartridge  30  or second cartridge  60  may be in fluid communication with recording head  21  via a flexible tube  20 , which may be connected to cartridge mounting portion  110  at one end and to recording head  21  at the other end. A sub-tank  28  may be positioned within recording head  21 . Sub-tank  28  may be configured to temporarily store ink supplied from cartridge  30  or  60  via flexible tube  20  and to supply ink to nozzles  29  of recording head  21 . Recording head  21  may be configured to eject ink selectively from nozzles  29 . 
     A pick-up roller  23  may pick up recording sheets from a sheet tray  15  one by one, and the picked-up recording sheet may be conveyed to a conveying path  24 . The recording sheet may be conveyed by a conveying means, e.g., conveying rollers  25 , onto a platen  26 . Recording head  21  selectively may eject ink onto the recording sheet, conveyed onto platen  26  by conveying rollers  25 , to record an image on the recording sheet. After the recording sheet is conveyed past platen  26 , output rollers  22  may output the recording sheet to an output tray  16 , which may be positioned on the most downstream side of conveying path  24  in a sheet conveying direction. 
     Referring to  FIGS. 2-4 , first cartridge  30  may be a container configured to store ink therein. First cartridge  30  selectively may be inserted into and disengaged from cartridge mounting portion  110  along an insertion/removal path  50 , respectively. More specifically, first cartridge  30  may be inserted into cartridge mounting portion  110  in an insertion direction  50   b  and may be removed, e.g., disengaged, from cartridge mounting portion  110  in a removal direction  50   a  opposite to insertion direction  50   b . Each of insertion/removal path  50 , insertion direction  50   b  and removal direction  50   a  may be parallel to a horizontal direction. 
     First cartridge  30  may comprise a main body  31  having a substantially rectangular parallelepiped shape. Main body  31  may have a flat, box shape having a width in a width direction  51 , a height in a height direction  52 , and a depth in a depth direction  53 , in which the width is less than each of the height and the depth. Width direction  51 , height direction  52 , and depth direction  53  may be substantially perpendicular to each other, and each of width direction  51 , height direction  52 , and depth direction  53  may be orthogonal to a plane formed by the other two directions. When first cartridge  30  selectively is inserted into and removed from cartridge mounting portion  110 , insertion/removal path  50  may be perpendicular to height direction  52  and parallel to depth direction  53 . 
     Main body  31  of first cartridge  30  may comprise a front wall  40  and a rear wall  42 . Rear wall  42  may be positioned opposite to front wall  40  in insertion/removal path  50 . When first cartridge  30  is inserted into cartridge mounting portion  110 , front wall  40  may face insertion direction  50   b , and rear wall  42  may face removal direction  50   a . Main body  31  of first cartridge  30  may comprise a top wall  39  and a bottom wall  41  opposite top wall  39  in height direction  52 . Top wall  39  may be connected to an upper end of front wall  40  at one end and connected to an upper end of rear wall  42  at the other end. Bottom wall  41  is connected to a lower end of front wall  40  at one end and connected to a lower end of rear wall  42  at the other end. First cartridge  30  selectively may be inserted into and removed from cartridge mounting portion  110  along insertion/removal path  50 , in an orientation as shown in  FIG. 2 , e.g., top wall  39  thereof facing upward and bottom wall  41  thereof facing downward. 
     Main body  31  may comprise an internal container  35  and a cover member  34  configured to cover internal container  35 . Internal container  35  may comprise an ink chamber  36  formed therein. Cover member  34  may comprise front wall  40 , rear wall  42 , top wall  39 , and bottom wall  41 . Ink chamber  36  formed in an interior of internal container  35  may extend over an area adjacent to front wall  40  and rear wall  42 . 
     A residual amount detection portion  33  may be positioned at a middle portion of front wall  40  of main body  31  in height direction  52 . Residual amount detection portion  33  may have an open-box shape with an open end. Residual amount detection portion  33  may be in fluid communication with ink chamber  36 , via the open end. Residual amount detection portion  33  may comprise a pair of walls comprising translucent, e.g., transparent or semi-transparent, resin configured to allow light, e.g., infrared or visible light, emitted from an optical sensor  114  to pass therethrough. Optical sensor  114  may be positioned at cartridge mounting portion  110 . When first cartridge  30  is mounted to cartridge mounting portion  110 , residual amount detection portion  33  may allow the light emitted from optical sensor  114  to pass therethrough, or may block or attenuate the light, depending on the amount of ink stored in ink chamber  36 . An amount of the light that passes through residual amount detection portion  33 , may be used to determine whether the residual ink amount in ink chamber  36  is less than a predetermined amount. Residual amount detection portion  33  may comprise a detection device, such as a light blocking plate positioned in residual amount detection portion  33  and configured to move based on the amount of ink stored in ink chamber  36 . Residual amount detection portion  33  may comprise a prism that diverts or bends the light in different directions based on the amount of ink stored in ink chamber  36 . The pair of walls irradiated with the light emitted from optical sensor  114  may be vertical, e.g., extending in height direction  52 , or may be inclined with respect to a vertical direction, e.g., inclined with respect to height direction  52 . 
     An air communication opening  32  may be positioned at front wall  40  above residual amount detection portion  33  in height direction  52 . In particular, air communication opening  32  may be formed through front wall  40  in depth direction  53 . Ink chamber  36  and the atmosphere outside first cartridge  30  may be placed into communication with each other via air communication opening  32 . Air communication opening  32  may be configured to be opened or closed selectively by a valve (not shown). When air communication opening  32  is opened, pressure in ink chamber  36  may equalize to atmospheric pressure. In another embodiment, air communication opening  32  may be positioned at a different location within main body  31  and may be configured to bring the interior of ink chamber  36  into fluid communication with the exterior of ink chamber  36 , e.g., the atmosphere. Further, in still another embodiment, if the interior of ink chamber  36  is maintained at negative pressure, air communication opening  32  may be omitted. 
     A communication portion, e.g., an ink supply portion  37 , may be positioned at front wall  40  below residual amount detection portion  33  in height direction  52 . Ink supply portion  37  may have a cylindrical outer shape. Ink supply portion  37  may extend outward from front wall  40  and perpendicular to front wall  40 , e.g., in an insertion direction  50   b . An ink flow path  38  may be formed in a middle portion of ink supply portion  37  to extend along insertion/removal path  50 . As shown in  FIG. 1 , ink stored in ink chamber  36  may flow into an ink supply tube  122  of cartridge mounting portion via ink flow path  38 . 
     A rear portion of top wall  39  of main body  31  in insertion direction  50   b  may be lower, in height direction  52 , than a front portion of top wall  39 . The rear portion of top wall  39  may be positioned closer to rear wall  42  than to front wall  40 , and the front portion of top wall  39  may be positioned closer to front wall  40  than to rear wall  42 . A vertical wall  43  may be formed substantially at a middle portion of top wall  39  along insertion/removal path  50 . Vertical wall  43  may comprise a plane extending in width direction  51  and height direction  52  of first cartridge  30 . As shown in FIGS.  1  and  8 - 13 , a lock lever  145  of cartridge mounting portion  110  may be configured to engage vertical wall  43  when first cartridge  30  is mounted to cartridge mounting portion  110 . Vertical wall  43  may be configured to receive an urging force that urges first cartridge  30  out of cartridge mounting portion  110  in removal direction  50   a.    
     First cartridge  30  may comprise a first protrusion  45  and a second protrusion  46 . First protrusion  45  may be disposed at the upper end of front wall  40  of main body  31 . The width of first protrusion  45  may be equal to the width of front wall  40  in width direction  51 . First protrusion  45  may be connected to or formed on front wall  40  and may extend outward from front wall  40 . For example, first protrusion  45  may extend in insertion direction  50   b  from front wall  40 . In another embodiment, first protrusion  45  may have a plate shape having a width which is less than the width of front wall  40  in width direction  51 . 
     Second protrusion  46  may be disposed at the lower end of front wall  40  of main body  31  below ink supply portion  37  in height direction  52 . The width of second protrusion  46  may be equal to the width of front wall  40 . Second protrusion  46  may be connected to or formed on front wall  40  and may extend outward from front wall  40 . Second protrusion  46  may extend in insertion direction  50   b  from front wall  40 . Second protrusion  46  may extend further than ink supply portion  37  in insertion direction  50   b , e.g., an end of second protrusion  46  may be disposed further from ink chamber  36  than an end of ink supply portion  37  is disposed from ink chamber  36 . In another embodiment, second protrusion  46  may have a plate shape and may have a width which is less than the width of front wall  40 . Referring to  FIG. 3 , second protrusion  46  may extend from front wall  40  in insertion direction  50   b  by a length L 1 . Length L 1  may be based on an ink capacity of first cartridge  30 . The length of the second protrusion may vary from one ink cartridge to another based on the ink capacity of the ink cartridge. For example, a cartridge having a different ink capacity than the ink capacity of first cartridge  30  may comprise a second protrusion having a different length than length L 1 . Length L 1  may have relationship with the initial amount of ink stored in ink chamber  36 . The length of the second protrusion may vary from one ink cartridge to another based on the initial amount of ink stored in each ink chambers. For example, a cartridge storing a different initial amount of ink than the initial amount of ink stored in first cartridge  30  may comprise a second protrusion having a different length than length L 1 . 
     Length L 1  of second protrusion  46  may be based on an outer shape of a rear portion of main body  31 . For example, length L 1  of second protrusion  46  may be based on an outer shape of rear wall  42  and a portion of main body  31  adjacent to rear wall  42 . The length of the second protrusion may vary from one ink cartridge to another based on the outer shape of the rear portion of a main body in each ink cartridges. For example, a cartridge comprising a main body whose rear portion has a different outer shape than the outer shape of the rear portion of main body  31  may comprise a second protrusion having a different length than length L 1 . As shown in  FIG. 3 , main body  31  of first cartridge  30  may have a rectangular shape in side view. Rear wall  42  may have a length L 3  in height direction  52 . Length L 3  may be based on an initial amount of ink stored in ink chamber  36 . The length of the rear wall may vary from one ink cartridge to another based on the initial amount of ink stored in an ink chamber of each ink cartridges. For example, a cartridge storing a different initial amount of ink than the initial amount of ink stored in first cartridge  30  may comprise a rear wall having a different length than length L 3 . 
     Main body  31  may have a length L 5  between front wall  40  and rear wall  42  along insertion/removal path  50 . Length L 5  may be independent of the cartridge capacity and may not vary from one ink cartridge to another based on length L 1  of second protrusion  46 . For example, a cartridge comprising a second protrusion having a different length than length L 1  may have the same length L 5  between a front wall and a rear wall of a main body. Moreover, a height of front wall  40 , e.g., a length L 7  between top wall  39  and bottom wall  41  of main body  31 , may be substantially equal to length L 3 . 
     In another embodiment, cover member  34  and internal container  35  of main body  31  may be an integrally-formed or integrally-molded component. In another embodiment, a main body  31  may comprise light-blocking resin. Main body  31  may be formed in a box-shape with an open end facing in insertion direction  50   b . Ink chamber  36  may be disposed in an interior of main body  31 . Cover  34  may comprise a translucent, e.g., transparent or semi-transparent, resin and may be attached to the open end of main body  31 . Cover  34  may comprise a front wall and a residual amount detection portion and an ink supply portion integrally formed at the front wall. A first protrusion and a second protrusion also may be connected to or formed on the front wall. 
     Referring to  FIGS. 5-7 , second cartridge  60  may be a container configured to store ink therein. Second cartridge  60  selectively may be inserted into or removed from cartridge mounting portion  110  along insertion/removal path  50 , e.g., insertion direction  50   b  or removal direction  50   a , respectively. 
     Second cartridge  60  may comprise a main body  61  having a substantially rectangular parallelepiped shape. Main body  61  may have a flat, box shape having a width in width direction  51 , a height in height direction  52 , and a depth in depth direction  53 , in which the width may be less than each of the height and the depth. Width direction  51 , height direction  52 , and depth direction  53  are perpendicular to each other. When second cartridge  60  selectively is inserted into and removed from cartridge mounting portion  110 , insertion/removal path  50  is perpendicular to height direction  52  and parallel to depth direction  53 . Main body  61  of second cartridge  60  may comprise a front wall  70  and a rear wall  72 . Rear wall  72  may be disposed opposite front wall  70  along insertion/removal path  50 . When second cartridge  60  is inserted into cartridge mounting portion  110 , front wall  70  may face in insertion direction  50   b , and rear wall  72  may face in removal direction  50   a . Main body  61  of second cartridge  60  may comprise a top wall  69  and a bottom wall  71  opposite top wall  69  in height direction  52 . A rear end of top wall  69  is connected to an upper end of rear wall  72 , and a front end of top wall  69  is connected to an upper end of front wall  70 . A front end of bottom wall  71  is connected to a lower end of front wall  70 , but a rear end of bottom wall  71  is not connected directly to a lower end of rear wall  72 . The rear end of bottom wall  71  is connected to the lower end of the rear wall  72  via a recessed corner portion  79 . Top wall  69  or bottom wall  71 , or both, may extend substantially parallel to insertion/removal path  50  of ink cartridge  60 . Guiding means may be provided on top wall  69  or bottom walls  71  to guide a movement of second cartridge  60  during insertion into or removal from cartridge mounting portion  110 . Second cartridge  60  selectively may be inserted into and removed from cartridge mounting portion  110  along insertion/removal path  50 , in an orientation shown in  FIG. 5 , e.g., with top wall  69  facing opposite to bottom wall  71  in height direction  52 . 
     Main body  61  may comprise an internal container  65  and a cover member  64  configured to cover internal container  65 . Internal container  65  may comprise an ink chamber  66  formed therein. Cover member  64  may comprise front wall  70 , rear wall  72 , top wall  69 , and bottom wall  71 . As shown in  FIG. 7 , ink chamber  66  may be formed in an interior of internal container  65  and may be separated from rear wall  72  by a predetermined distance. Ink chamber  66  may have a length in depth direction  53  less than a length of ink chamber  36  of first cartridge  30 . Ink chamber  66  may have an ink capacity less than an ink capacity of ink chamber  36  of first cartridge  30 . 
     A residual amount detection portion  63  may be positioned substantially at a middle portion of front wall  70  of main body  61  in height direction  52 . Residual amount detection portion  63  may have an open-box shape with an open end. Residual amount detection portion  63  may be configured to be in fluid communication with ink chamber  66  via the open end. Residual amount detection portion  63  may comprise a pair of walls comprising translucent, e.g., transparent or semi-transparent, resin configured to allow light, e.g., infrared or visible light, emitted from optical sensor  114  to pass therethrough. Optical sensor  114  may be positioned at cartridge mounting portion  110 . When second cartridge  60  is mounted to cartridge mounting portion  110 , residual amount detection portion  63  may allow the light emitted from optical sensor  114  to pass therethrough, or may block or attenuate the light, depending on an amount of ink stored in ink chamber  66 . Based on an amount of light passing through residual amount detection portion  63 , it may be determined whether the residual ink amount in ink chamber  66  may be determined to be less than a predetermined amount. Residual amount detection portion  63  may comprise a detection device, e.g., a light blocking plate, positioned in residual amount detection portion  63  and configured to move based on the amount of ink stored in ink chamber  66 . Residual amount detection portion  63  may comprise a prism that diverts or bends light in different directions based on the amount of ink stored in ink chamber  66 . The pair of walls irradiated with the light emitted from optical sensor  114  may be vertical, e.g., extending in height direction  52 , or may be inclined with respect to the vertical direction, e.g., inclined with respect to height direction  52 . 
     An air communication opening  62  may be positioned at front wall  70  above residual amount detection portion  63  in height direction  52 . In particular, air communication opening  62  may be formed through front wall  70  in depth direction  53 . Ink chamber  66  and the atmosphere outside the second cartridge  60  may be placed into fluid communication with each other via air communication opening  62 . Air communication opening  62  may be configured to be opened and closed selectively by a valve (not shown). When air communication opening  62  is opened, pressure in ink chamber  66  may equalize to atmospheric pressure. In another embodiment, air communication opening  62  may be disposed at a different location within main body  61  and may be configured to bring the interior of ink chamber  66  into fluid communication with the exterior of ink chamber  66 , e.g., the atmosphere. Further, in yet another embodiment, if the interior of ink chamber  66  is maintained at negative pressure, air communication opening  62  may be omitted. 
     A communication portion, e.g., an ink supply portion  67 , may be disposed at front wall  70  below residual amount detection portion  63  in height direction  52 . Ink supply portion  67  may have a cylindrical outer shape. Ink supply portion  67  may extend outward from and perpendicular to front wall  70 . An ink flow path  68  may be formed in a middle portion of ink supply portion  67  to extend along insertion/removal path  50 . Ink stored in ink chamber  66  may flow into ink supply tube  122  via ink flow path  68 . 
     A rear portion of top wall  69  of main body  61  in insertion direction  50   b  may be lower, in height direction  52 , than a front portion of top wall  69 . The rear portion of top wall  69  may be disposed closer to rear wall  72  than to front wall  70 , and the front portion of top wall  69  may be disposed closer to front wall  70  than to rear wall  72 . A vertical wall  73  may be formed substantially at a middle portion of top wall  69  along insertion/removal path  50 . Vertical wall  73  may comprise a plane extending in width direction  51  and height direction  52  of second cartridge  60 . As shown FIGS.  1  and  8 - 13 , lock lever  145  of cartridge mounting portion  110  may be configured to engage vertical wall  73  when second cartridge  60  is mounted to cartridge mounting portion  110 . Vertical wall  73  may be configured to receive an urging force that urges second cartridge  60  out of cartridge mounting portion  110  in removal direction  50   a.    
     Second cartridge  60  may comprise a first protrusion  75  and a second protrusion  76 . First protrusion  75  may be disposed at the upper end of front wall  70  of main body  61 . A width of first protrusion  75  may be equal to a width of front wall  70  in width direction  51 . First protrusion  75  may be connected to or formed on front wall  70  and may extend outward from front wall  70 . For example, first protrusion  75  may extend in insertion direction  50   b  away from front wall  70 . In another embodiment, first protrusion  75  may have a plate shape having a width which is less than the width of front wall  70  in width direction  51 . 
     Second protrusion  76  may be disposed at the lower end of front wall  70  of main body  61  below ink supply portion  67  in height direction  52 . Second protrusion  76  may be positioned adjacent to bottom wall  71  of main body  61 . A width of second protrusion  76  may be equal to a width of front wall  70 . Second protrusion  76  may be connected to or formed on front wall  70  and may extend outward from front wall  70 . Second protrusion  76  may extend in insertion direction  50   b  away from front wall  70 . Second protrusion  76  may extend further from front wall  70  than ink supply portion  67  extends from front wall  70  in insertion direction  50   b , e.g., an end of second protrusion  76  may be disposed further away from ink chamber  66  than an end of ink supply portion  67  is disposed away from ink chamber  66 . Moreover, the end of second protrusion  76  may protrude further in insertion direction  50   b  than an end of first protrusion  75 . In another embodiment, second protrusion  76  may have a plate shape having a width which is less than the width of front wall  70 . Referring to  FIG. 6 , second protrusion  76  may extend from front wall  70  in insertion direction  50   b  by a length L 2 . Length L 2  may be based on an ink capacity of second cartridge  60 . The length of the second protrusion may vary from one cartridge to another based on the ink capacity of cartridge. For example, a cartridge having a different ink capacity than the ink capacity of second cartridge  60  may comprise a second protrusion having a different length than length L 2 . Length L 2  may have a relationship with the initial amount of ink stored in ink chamber  66 . The length of the second protrusion may vary from one cartridge to another based on the initial amount of ink stored in the cartridges. For example, a cartridge storing a different initial amount of ink than the initial amount of ink stored in second cartridge  60  may comprise a second protrusion having a different length than length L 2 . 
     Length L 1  of first cartridge  30  may be different from length L 2  of second cartridge  60  in insertion/removal path  50  based on the ink capacities of first cartridge  30  and second cartridge  60  and based on the initial amounts of ink stored in ink chambers  36  and  66 . Length L 2  may be longer than length L 1 . In another embodiment, length L 1  of first cartridge  30  may be different from length L 2  of second cartridge  60  in insertion/removal path  50  based on the colors of ink stored in ink chambers  36  and  66 , e.g., based on coloring agents, a dye or a pigment, of ink stored in ink chambers  36  and  66 , or based on the prices of ink cartridges  30  and  60 , e.g., a higher price cartridge or a lower price cartridge. 
     Length L 2  of second protrusion  76  may be based on an outer shape of the rear portion of main body  61 . For example, length L 2  of second protrusion  76  may be based on an outer shape of rear wall  72  and a portion of main body  61  adjacent to rear wall  72 . The length of the second protrusion may vary from one cartridge to another based on the outer shape of the rear portion of a main body of cartridges. For example, a cartridge comprising a main body whose rear portion has a different outer shape than the outer shape of the rear portion of main body  61  may comprise a second protrusion having a different length than length L 2 . As shown in  FIG. 6 , main body  61  of second cartridge  60  may have a rectangular shape from which a corner portion thereof adjacent to rear wall  72  may be cut out, such that recessed corner portion  79  may be formed adjacent to rear wall  72 . Rear wall  72  may have a length L 4  in height direction  52 . Length L 4  may be based on an initial amount of ink stored in ink chamber  66 . The length of the rear wall may vary from one cartridge to another based on the initial amount of ink stored in an ink chamber. For example, a cartridge storing a different initial amount of ink than the initial amount of ink stored in second cartridge  60  may comprise a rear wall having a different length than length L 4 . A height of front wall  70 , e.g., a length L 7  between top wall  69  and bottom wall  71 , may be equal to length L 7  between top wall  39  and bottom wall  41  of main body  31  of first cartridge  30 . Length L 4  may be shorter than length L 3  of rear wall  42  of first cartridge  30 . More specifically, length L 4  may be shorter than length L 7  between bottom wall  71  and top wall  69  of second cartridge  60  in height direction  52 . Length L 4  may be less than or equal to seventy-five percent of length L 7  between bottom wall  71  and top wall  69 . This range is found to yield suitable dimensions for holding portion  74 , such that a user may hold, insert or remove the cartridge with ease. 
     Main body  61  may have a length L 6  between front wall  70  and rear wall  72  along insertion/removal path  50 . Length L 6  may be independent of the cartridge and may not vary from one ink cartridge to another based on length L 2  of second protrusion  76 . For example, a cartridge comprising a second protrusion having a different length than length L 2  may have the same length L 6  between a front wall and a rear wall of a main body. Therefore, length L 6  of second cartridge  60  may be equal to length L 5  of first cartridge  30 . The width of main body  61  of second cartridge  60  in width direction  51  may be equal to the width of main body  31  of first cartridge  30  in width direction  51 . 
     Holding portion  74  may comprise a pair of side walls  77  and  78  each connected to upper wall  69  and recessed corner portion  79 . Upper wall  69  may be connected to the upper end of rear wall  72 . Recessed corner portion  79  may be connected to for formed within the lower end of rear wall  72 . Holding portion  74  may be grasped by a user to remove second cartridge  60  from cartridge mounting portion  110 . A length L 9  extending from the rear end of bottom wall  71  to the end of second protrusion  76  in insertion direction  50   b  may be less than a total length, e.g., L 2 +L 6 , of second cartridge  60 . The total length of second cartridge  60  may extend from an end of holding portion  74  to the end of second protrusion  76  in insertion direction  50   b . Bottom wall  71  may provide a guiding means and a sliding surface, or both, for cartridge upon insertion and removal and holding portion  74  may allow the cartridge to reach further outside of cartridge mounting portion  110  than proximate to a rear end of the bottom wall  71  during insertion or removal of the cartridge. Therefore, the cartridge may be removed more easily by means of holding portion  74 . 
     In another embodiment, cover member  64  and internal container  65  of main body  61  may be an integrally-formed or integrally-molded component. In yet another embodiment, main body  61  may comprise light-blocking resin. Main body  61  may be formed into a box-shape with an open end facing frontward in insertion direction  50   b . Ink chamber  66  may be disposed in an interior of main body  61 . A cover comprising a translucent, e.g., transparent or semi-transparent, resin may be attached to the open end. The cover may comprise a front wall, and a residual amount detection portion and an ink supply portion integrally formed at the front wall. A first protrusion and a second protrusion may be connected to or formed within the front wall. 
     Referring to  FIGS. 1 and 8 , cartridge mounting portion  110  may have opening  112  formed therethrough. First cartridge  30  and second cartridge  60  respectively may be configured to be mounted removably on cartridge mounting portion  110 . Cartridge mounting portion  110  may comprise a horizontally-extending supporting surface  108 , and cartridges  30  and  60 , respectively, may be configured to slide on supporting surface  108  along insertion/removal path  50  when cartridges  30  and  60 , respectively are inserted into and removed from cartridge mounting portion  110 . Supporting surface  108  may be an inner bottom surface facing the inner space of cartridge mounting portion  110 . 
     Cartridge mounting portion  110  may comprise optical sensor  114 , a lock mechanism  144 , a slide member  135 , a coil spring  139 , and a coupling portion  121 . Optical sensor  114  may be disposed at an end of cartridge mounting portion  110  opposite opening  112 , and optical sensor  114  may extend into an inner space of cartridge mounting portion  110 . Optical sensor  114  may be configured to detect the detection device, e.g., a light blocking plate, disposed in residual amount detection portion  33  or  63  if residual amount detection portion  33  or  63  comprises the detection device. Optical sensor  114  may be a transmissive photo-interrupter comprising a light-emitting element, e.g., light-emitting diode, configured to emit light, e.g., visible light or infrared light, and a light-receiving element, e.g., a phototransistor, configured to receive the light emitted from the light-emitting element. The light-emitting element and the light-receiving element may be positioned with a distance therebetween in width direction  51 . When cartridge  30  or  60  is mounted to cartridge mounting portion  110 , residual amount detection portion  33  or  63  may be disposed between the light-emitting element and the light-receiving element. Depending on the amount of ink stored in cartridge  30  or  60 , the detection device may block the light emitted from the light-emitting element, such that the light does not reach the light receiving element, or the detection device may not block the light, such that the light receiving element receives the light. It may be determined whether the amount ink stored in cartridge  30  or  60  is less than the predetermined amount, based on an amount of light received by optical sensor  114 . 
     In another embodiment, instead of the detection device blocking the light, the light emitted from the light-emitting element may be attenuated or deviated when there is ink in residual amount detection portion  33  or  63 , and may pass through residual amount detection portion  33  or  63  when there is no ink in residual amount detection portion  33  or  63 . Alternatively, the light emitted from the light-emitting element may be reflected on or in the ink in residual amount detection portion  33  or  63  so as not to reach the light-receiving element when there is ink in residual amount detection portion  33  or  63 , and the light may be reflected on or in the residual amount detection portion  33  or  63  so as to be received by the light-receiving element when there is no ink in residual amount detection portion  33  or  63 . 
     A slide member  135  may be disposed in a space  130  formed at a lower portion of the end of cartridge mounting portion  110  opposite opening  112  in height direction  52 . Space  130  may be continuous with the inner space of cartridge mounting portion  110  via one end of space  130  along insertion/removal path  50  and the other end of space  130  may be bounded by a back wall  133 . Slide member  135  may be slidably supported in space  130 , such that slide member  135  may slide along insertion/removal path  50 . Slide member  135  may be disposed so as to selectively contact second protrusion  46  of first cartridge  30  and second protrusion  76  of second cartridge  60  when cartridge  30  or  60  is mounted to cartridge mounting portion  110 , respectively. 
     As shown in  FIGS. 8-13 , further optical sensors  115  and  116  may be disposed in cartridge mounting portion  110 . Optical sensors  115  and  116  may have substantially the same optical properties as optical sensor  114 . When first or second cartridge  30 ,  60  is inserted into cartridge mounting portion  110 , the corresponding first protrusion  45  or  75 , respectively, may block or interrupt an optical path of optical sensor  115  which is indicative of the presence of ink cartridge  30  or  60  inside the recording apparatus. Thus, first protrusion  45  or  75  may form a light blocking portion. Similarly, second protrusions  46  or  76  may contact spring-biased slide member  135 , which may block or interrupt an optical path of optical sensor  116  depending on length L 1  or L 2  of the second protrusion. Because length L 1  or L 2  may be associated with an initial amount of ink in the cartridge or with an ink capacity of the cartridge, second protrusion  46  or  76  may be indicative of the initial ink amount or ink capacity. 
     Coil spring  139  may be disposed in space  130 . Coil spring  139  may urge slide member  135  elastically toward opening  112 , e.g., in removal direction  50   a . One end of coil spring  139  may be connected to back wall  133 . The other end of coil spring  139  may be connected to slide member  135 . As shown in  FIG. 10 , when coil spring  139  is at its natural length, e.g., when no external force is applied to coil spring  139  via slide member  135 , slide member  135  may be disposed closer to opening  122 . Second protrusion  46  or  76  may contact and push slide member  135  toward back wall  133  during the insertion of cartridge  30  or  60  into cartridge mounting portion  110 . As shown in  FIG. 8 , coil spring  139  may be compressed, and slide member  135  may slide toward back wall  133 . The distance by which slide member  135  is moved toward back wall  133 , may depend on length L 1  or L 2  of second protrusion  46  or  76 , respectively. 
     Lock mechanism  144  may be disposed at an upper portion of cartridge mounting portion  110 . When cartridge  30  or  60  is mounted to cartridge mounting portion  110 , lock mechanism  144  may be configured to retain cartridge  30  or  60  in a mounted position in cartridge mounting portion  110  by restricting the movement of cartridge  30  or  60  in removal direction  50   a , e.g., a leftward direction in  FIGS. 8-13 . 
     Lock mechanism  144  may comprise lock lever  145  and a coil spring  148  configured to apply an urging force to lock lever  145 . Lock lever  145  may be supported pivotally, such that lock lever  145  may pivot between an unlock position, as shown in  FIGS. 9 ,  10 ,  12  and  13 , and a lock position, as shown in  FIGS. 8 and 11 . In the absence of an external force applied to lock lever  145 , coil spring  148  may bias lock lever  145  toward the lock position. An end of lock lever  145  may comprise an engagement end  146 . Lock lever  145  may lock or retain cartridge  30  or  60  in the mounted position in cartridge mounting portion  110  when engagement end  146  engages vertical wall  43 ,  73  of cartridge  30  or  60 . 
     A coupling portion  121  may be disposed at the end of cartridge mounting portion  110  opposite opening  112 . Coupling portion  121  may extend into the inner space of cartridge mounting portion  110 . As shown in  FIG. 1 , coupling portion  121  may comprise ink supply tube  122 . Ink supply tube  122  may extend along insertion/removal path  50 . Ink supply tube  122  may be connected to flexible tube  20 . When cartridge  30  or  60  is mounted to cartridge mounting portion  110 , ink supply tube  122  may be inserted into ink flow path  38  or  68  of ink supply portion  37  or  67 , respectively. Thus, coupling portion  121  may be connected to ink supply portion  37  or  67 . Ink stored in ink chamber  36  or  66  may be supplied to flexible tube  20  via ink supply tube  122 . 
     Referring to  FIG. 8 , when first cartridge  30  is inserted into cartridge mounting portion  110 , slide member  135  may slide toward back wall  133  while being pushed by second protrusion  46 . While slide member  135  slides, coil spring  139  may contract from its natural length. When coil spring  139  contracts, slide member  135  may receive an urging force directed toward opening  112  from coil spring  139 . Thus, first cartridge  30  mounted in cartridge mounting portion  110  may be urged elastically toward opening  112 . 
     When vertical wall  43  of first cartridge  30  moves beyond engagement end  146  of lock lever  145  toward the end of cartridge mounting portion  110  opposite  112  during the insertion of first cartridge  30  into cartridge mounting portion  110 , lock lever  145  may pivot, such that engagement end  146  moves to a position in which engagement end  146  may engage vertical wall  43 . First cartridge  30  may be urged elastically by coil spring  139  via slide member  135  toward opening  112 . Nevertheless, as shown in  FIG. 8 , because engagement end  146  engages vertical wall  43 , first cartridge  30  may be retained in the mounted position in cartridge mounting portion  110 . When first cartridge  30  is retained in the mounted position in cartridge mounting portion  110 , ink supply tube  122  of coupling portion  121  may be inserted into ink flow path  38  of first cartridge  30 , such that ink stored in ink chamber  36  may be supplied to the exterior of first cartridge  30 . 
     Referring to  FIG. 9 , when first cartridge  30  is removed from cartridge mounting portion  110 , an operating portion  147  of lock lever  145  opposite engagement end  146  may be depressed. As shown in  FIG. 9 , depressing operating portion  147  may cause lock lever  145  to pivot counterclockwise to move from the lock position to the unlock position. When lock lever  145  is in the unlock position, engagement end  146  may separate from vertical wall  43  and be positioned above vertical wall  43 . Coil spring  139  then may expand, and first cartridge  30  may be moved toward opening  122  in removal direction  50   a  by the elastic urging force of coil spring  139  via slide member  135 . Ink supply tube  122  of coupling portion  121  may be removed from ink flow path  38  of first cartridge  30 . 
     Referring to  FIG. 10 , when coil spring  139  further expands and is returned to its natural length, first cartridge  30  may not receive the elastic urging force of coil spring  139  and may stop moving due to the friction between first cartridge  30  and supporting surface  108 . When coil spring  139  stops expanding, the rear portion of main body  31  of first cartridge  30  may come out of cartridge mounting portion  110  via opening  112  and may be disposed outside cartridge mounting portion  110 . The length of the portion of main body  31  disposed outside cartridge mounting portion  110  along insertion/removal path  50 , e.g., the distance between the rear wall  42  and the opening  112 , may depend on length L 1  of second protrusion  46  and length L 5  of main body  31 . 
     Referring to  FIG. 11 , when second cartridge  60  is inserted into cartridge mounting portion  110 , slide member  135  may slide toward back wall  133  while being urged by second protrusion  76 . While slide member  135  slides, coil spring  139  may contract from its natural length. When coil spring  139  contracts, slide member  135  may receive an urging force directed toward opening  112  from coil spring  139 . Thus, second cartridge  60  mounted in cartridge mounting portion  110  may be urged elastically toward opening  112 . 
     When vertical wall  73  of second cartridge  60  moves beyond engagement end  146  of lock lever  145  toward the end of cartridge mounting portion  110  opposite  112  during the insertion of second cartridge  60  into cartridge mounting portion  110 , lock lever  145  may pivot, such that engagement end  146  moves to a position in which engagement end  146  may engage vertical wall  73 . Second cartridge  60  may be urged elastically by coil spring  139  via slide member  135  toward opening  112 . As shown in  FIG. 11 , engagement end  146  may engage vertical wall  73 , and second cartridge  60  may be retained in the mounted position in cartridge mounting portion  110 . When second cartridge  60  is retained in the mounted position in cartridge mounting portion  110 , ink supply tube  122  of coupling portion  121  may be inserted into ink flow path  68  of second cartridge  60 , such that ink stored in ink chamber  66  may be supplied to the exterior of second cartridge  60 . 
     Referring to  FIG. 12 , when second cartridge  60  is to be removed from cartridge mounting portion  110 , operating portion  147  of lock lever  145  may be depressed. As shown in  FIG. 12 , depressing on operating portion  147  may cause lock lever  145  to pivot counterclockwise to move from the lock position to the unlock position. When lock lever  145  is in the unlock position, engagement end  146  may separate from vertical wall  73  and be positioned above vertical wall  73 . Coil spring  139  then may expand, and second cartridge  60  may be moved toward opening  122  in removal direction  50   a  by the elastic urging force of coil spring  139  via slide member  135 . Ink supply tube  122  of coupling portion  121  may be removed from ink flow path  68  of second cartridge  60 . Referring to  FIG. 13 , when coil spring  139  further expands and is returned to its natural length, second cartridge  60  does not receive the elastic urging force of coil spring  139  and stops moving by the friction between second cartridge  60  and supporting surface  108 . When coil spring  139  stops expanding, the rear portion of main body  61  may have come out of cartridge mounting portion  110  via opening  112  and be disposed outside cartridge mounting portion  110 . The length of the portion of main body  61  disposed outside cartridge mounting portion  110  along insertion/removal path  50 , e.g., the distance between the rear wall  72 , and the opening  112  may depend on length L 2  of second protrusion  76  and length L 6  of main body  61 . Length L 6  of main body  61  may be equal to length L 5  of main body  31 . Nevertheless, length L 2  of second protrusion  76  may be longer than length L 1  of second protrusion  46 . Therefore, the length of the portion of main body  61  disposed outside cartridge mounting portion  110  may be longer than the length of the portion of main body  31  positioned outside cartridge mounting portion  110  by the difference between lengths L 2  and L 1 . 
     Various types of cartridges, e.g., with various ink capacities and initial amounts of ink stored in the cartridges, may be readily distinguished by their appearances due to differences of lengths of second protrusion along insertion/removal path  50 , even through the shapes or sizes of main bodies are substantially the same or similar. 
     More specifically, the various types of cartridges may be distinguished by a comparison of the length of a first difference between the sum of lengths L 1  and L 5  on the one side and a total length, i.e., sum of L 1  and L 5 , of first cartridge  30  on the other side when measured along insertion direction  50   b , with a second difference between the length L 9  on the one side and the total length i.e., L 2 +L 6  of second cartridge  60  on the other side. A comparison of these lengths may readily be accomplished since these lengths are clearly visible to a user viewing the installed cartridges from outside cartridge mounting portion  110  allowing the user to distinguish between cartridges  30  and  60 . Thereby, the sum of lengths L 1  and L 5  or the sum of lengths L 2  and L 6  may be a distance extending from rear end of bottom wall  41  of first cartridge  30  to an end of protrusion  46  of first cartridge  30 , i.e., tip of protrusion extending most forward in insertion direction  50   b , in insertion direction  50   b , or a distance extending from a rear end of bottom wall  71  of second cartridge  60  to a corresponding end of protrusion  76  of second cartridge  60  in insertion direction  50   b . The end of the protrusion may be a portion which contacts sliding member  135 . Cartridges may be distinguished from each other by comparing a length difference between a length of a bottom section of the cartridge with a total length of the cartridge. For example, first cartridge  30  has a length difference of zero, and second cartridge  60  has a length difference greater than zero. 
     By changing the dimension of the corner portions at the rear portion of the ink cartridges, ink capacities of ink chambers  36  and  66  may be changed without changing the widths of cartridges  30  and  60  in width direction  51 . Therefore, a printer for business use may not require a cartridge having a wide dimension in width direction  51 , and, therefore, cartridge mounting portion  110  may not have a significant, non-utilized space in width direction  51 . Accordingly, the physical size of printer  10  may be reduced. 
     With this configuration, reduction of physical size of the recording apparatus in a width direction may not be prevented, because the capacity of the ink cartridge may be changed by the first difference between the lengths of the first cartridge along the insertion direction and the second difference between the lengths of the second cartridge along the insertion direction. Moreover or alternatively, an appearance of the ink cartridge, i.e., the first difference between the lengths of the first cartridge along the insertion direction and the second difference between the lengths of the second cartridge along the insertion direction, may indicate a type of the ink cartridge, e.g., may indicate an ink capacity of the ink cartridge. Thus, a user easily may recognize which cartridge is mounted in the cartridge mounting portion simply by viewing the cartridge in the insertion direction from the outside of cartridge mounting portion, without removing the cartridge from the cartridge mounting portion. 
     While length L 5  between front wall  40  and rear wall  42  of main body  31  and length L 6  between front wall  70  and rear wall  72  of main body  61  may be equal, lengths L 1  and L 2  of second protrusions  46  and  76  may be different. Therefore, when cartridges  30  and  60  are removed from cartridge mounting portion  110 , and when cartridges  30  and  60  are moved toward opening  112 , the positions at which cartridges  30  and  60  stop moving along insertion/removal path  50  may differ due to the differences between length L 1  and length L 2  of second protrusion  46  and  76 , respectively. As shown in  FIGS. 10 and 13 , second cartridge  60  with second protrusion  76  having the greater length L 2  stops at a position further outside off cartridge mounting portion  110  than first cartridge  30  because second protrusion  76  is longer with regard to second cartridge  60  and because urging member  139  is more biased when second cartridge  60  is inserted in cartridge mounting portion  110 . Consequently, removal of second cartridge  60  may be facilitated by a combination of the holding portion  74 , as described above, and the greater length of second protrusion  76 . 
     Due to the greater length L 2  of second protrusion  76  of second cartridge  60 , as compared with length L 1  of second protrusion  46  of first cartridge  30 , second protrusion  76  may protrude further in insertion direction  50   b , when cartridges  30  and  60  are mounted in cartridge mounting portion  110 , respectively. Consequently, urging member  139  may be more biased when second cartridge  60  is inserted than when first cartridge  30  is inserted. Therefore, first cartridge  30  also may be ejected similar to second cartridge  60 , but may stop at a position closer to urging member  139  in removal direction  50   a  than second carriage  60  does when second cartridge  60  is ejected by urging member  139 . Further, when cartridges  30  and  60  are in a state of completed installation within cartridge mounting portion  110  of recording apparatus  10 , sliding member  135  may be pushed further in insertion direction  50   b  in case of second cartridge  60  than in the case of first cartridge  30 . Second protrusion  76  of second cartridge  60  protrudes further in insertion direction  50   b  and thus further into recording apparatus  10 , e.g., beyond an end face of the cartridge mounting portion  110 . Sliding member  135  may serve as a light blocking portion indicative of a property of the ink cartridge  30  or  60 , e.g., ink capacity or initial ink amount stored within the ink chamber  36  or  66 . 
     Thus, the different lengths L 1  and L 2 , or the comparatively greater distance by which second protrusion  76  of second cartridge  60  extends into cartridge mounting portion  110  along insertion direction  50   b  may allow the characteristic, e.g., ink capacity, of a cartridge, e.g., first cartridge  30 , to be readily distinguished from another cartridge, e.g., second cartridge  60 , by sensors  116  and associated integrated circuits (not shown) of the recording apparatus. In addition, when first cartridge  30  and second cartridge  60  are mounted in cartridge mounting portions  110  adjacent to each other in width direction  51 , instead of in place of each other, holding portion  74  of second cartridge  60  may be grasped by a user to readily remove second cartridge  60 . This may become particularly advantageous, when multiple cartridges are to be replaced one after the other, and the second cartridge is removed first. 
     Lengths L 1  and L 2  of second protrusions  46  and  76 , respectively, may be based on the outer shapes of rear portions of main bodies  31  and  61 . Therefore, even when second protrusion  46  or  76  is not able to be seen when first cartridge  30  or second cartridge  60  is mounted to cartridge mounting portion  110 , whether a cartridge is first cartridge  30  or second cartridge  60  may be identified by the outer shape of the rear portion of main body  31  or  61 , respectively, when a user examines first cartridge  30  or second cartridge  60  from the outside of cartridge mounting portion  110  in insertion direction  50   b.    
     Shapes of outer surfaces of top walls  39  and  69  may be substantially the same between cartridges  30  and  60  regardless of the length of second protrusions  46 ,  76 . Therefore, vertical walls  43  and  73  may be disposed at substantially same position at top walls  39  and  69 , respectively, between cartridges  30 ,  60 . 
     Length L 3  may be substantially equal to length L 7 . Further, top wall  39  and bottom wall  41  may be substantially perpendicular to front wall  40  and rear wall  42 . Therefore, main body  31  may have a substantially rectangular parallelepiped shape, and the ink capacity of ink chamber  36  of first cartridge  30  may be readily increased. 
     In the above-described embodiment, length L 1  of second protrusion  46  of first cartridge  30  and length L 2  of second protrusion  76  of second cartridge  60  may be different. Similarly, in another embodiment, first protrusion  45  of first cartridge  30  and first protrusion  75  of second cartridge  60  may be structured to have different lengths. In this case, slide member  135  and coil spring  139  may be positioned at an upper portion of cartridge mounting portion  110  so as to contact first protrusions  45 ,  75 . 
     In the above-described embodiment, holding portion  74  is formed via a recessed corner portion  79  which extends between the bottom wall  71  and the rear wall  72 . Recessed corner portion  79  results in a reduced vertical dimension, i.e., length L 4 , of the rear portion of the cartridge, thereby forming holding portion  74 , by which the cartridge may be gripped at holding portion  74 . In an alternative embodiment, main body  61  may not comprise recessed corner portion  79 , but instead may comprise a resilient, elastic or deformable member extending from rear wall  72  or from one or both of the pair of side walls  77 ,  78  adjacent to rear wall  72  in removal direction  50   a , e.g., in the rearward direction, which may allow the cartridge to be withdrawn from cartridge mounting portion  110 . More specifically, in this alternative embodiment, the rear wall  72  may extend directly from the rear end of the bottom wall  71  up to the rear end of the top wall  69 , and the resilient, elastic or deformable member, e.g., a spring or a bellows-like member may extend from the rear wall  72  or from one or both of the pair of side walls  77 ,  78  adjacent to the rear wall  72  in removal direction  50   a . Even without the recessed corner portion  79 , the total length of the cartridge measured along insertion/removal path  50 , i.e., the length extending from the rear end of the resilient, elastic, or deformable member to the front end of protrusion  76  and in insertion direction  50   b , may be greater than length L 9 , i.e., the length extending from the rear end of bottom wall  71  to the front end of protrusion  76  in insertion direction  50   b , whereby space may be saved. 
     In another alternative embodiment, main body  61  may not comprise recessed corner portion  79 , but instead may comprise a pivot member which extends from the corner between rear wall  72  and top wall  69  in removal direction  50   a , i.e., in the rearward direction, and is configured to pivot about the corner between rear wall  72  and top wall  69 . More specifically, in this alternative embodiment, rear wall  72  may extends directly from the rear end of the bottom wall  71  up to the rear end of top wall  69 , and the pivot member may be configured to pivot about the corner between rear wall  72  and top wall  69 . Even without the recessed corner portion  79 , the total length of the cartridge measured along insertion/removal path  50 , i.e., the length extending from the rear end of the pivot member to the front end of the protrusion  76  in insertion direction  50   b , may be greater than length L 9 , i.e., the length extending from the rear end of the bottom wall  71  to the front end of the protrusion  76  in insertion direction  50   b.    
     While the invention has been described in connection with various example structures and illustrative embodiments, it will be understood by those skilled in the art that other variations and modifications of the structures and embodiments described above may be made without departing from the scope of the invention. Other structures and embodiments will be apparent to those skilled in the art from a consideration of the specification or practice of the invention disclosed herein. It is intended that the specification and the described examples are illustrative with the true scope of the invention being defined by the following claims.