Patent Publication Number: US-7216963-B2

Title: Ink cartridge and ink-jet recording apparatus using the ink cartridge

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an ink cartridge that stores ink to be supplied to an ink-jet head, and also relates to an ink-jet recording apparatus using the ink cartridge. 
   2. Description of Related Art 
   In an ink-jet recording apparatus such as ink-jet is printers, in order to record a good image on a recording medium, it is important that proper meniscus is formed at each nozzle of an ink-jet head. For keeping meniscus of nozzles in a proper condition, pressure applied to the nozzles should be kept within a predetermined range. 
   When positive pressure or excessively small negative pressure is applied to nozzles, meniscus is broken to cause such a disadvantage as ink dripping from the nozzles. Besides, when excessive negative pressure is applied to nozzles, air bubbles can enter the nozzles to disadvantageously cause ink ejection disability, unstable ejection, and the like. Therefore, pressure to be applied to nozzles has to fall within a predetermined negative range. 
   Thus, known is a technique of producing negative pressure in nozzles by means of a difference in level between an ink-jet head including nozzles and a cartridge for storing liquid that will be supplied to the head (see U.S. Patent Application Publication No. 2002122084). According to this technique, a cartridge is mounted in a horizontal manner. An upper face of a liquid bag included in the cartridge is fixed to a housing, while a lower face of the liquid bag is freely movable depending on a change in the amount of liquid therein, so that the lower face moves upward when the amount of liquid decreases. As a result, even when the amount of liquid in the liquid bag is changed, pressure applied to nozzles does not vary so much and can be kept within a predetermined range. 
   SUMMARY OF THE INVENTION 
   In this technique, however, as a cartridge is horizontally mounted, an area on a horizontal plane occupied by a whole of the cartridge becomes relatively larger. This causes a problem that a recording apparatus increases in size in a horizontal direction. 
   When a cartridge is vertically mounted, on the other hand, pressure applied to nozzles largely varies depending on a change in the amount of liquid within the liquid bag. 
   An object of the present invention is to provide an ink cartridge capable of suppressing a variation in pressure applied to nozzles and reducing an area on a horizontal plane occupied by a whole of the cartridge itself, and to provide an ink-jet recording apparatus using the ink-cartridge. 
   According to a first aspect of the present invention, there is provided an ink cartridge being vertically mounted comprises a housing that is provided with an ink discharge port, an ink pack that is disposed within the housing, and a pressing mechanism that presses the ink pack. The pressing mechanism includes a contact and a biasing member. The contact is movably disposed within the housing and in contact with at least a part of the ink pack lower than the ink discharge port. The biasing member biases the contact toward the ink pack in a direction at an angle to a vertical direction. 
   According to a second aspect of the present invention, there is provided an ink cartridge comprises a housing, an ink pack that stores ink, and a pressing mechanism th at presses the ink pack. The housing has a plurality of vertical walls each extending in a vertical direction, at least one of the vertical walls being vertically long. The ink pack has an opening for discharging ink and is disposed within the housing. The pressing mechanism includes a contact and a biasing member. The contact is movably disposed within the housing and in contact with a part of the ink pack lower than the opening. The biasing member biases the contact toward the ink pack, and is positioned between the contact and one of the vertical walls of the housing with one end and the other end thereof respectively connected to the contact and the one vertical wall. 
   With the foregoing first and second aspects, an area on a horizontal plane occupied by the cartridge becomes smaller as compared with either an ink cartridge being horizontally mounted or comprising a housing with no wall vertically long. In addition, since the aforementioned pressing mechanism including the contact and the biasing member is provided, a variation in pressure applied to the nozzles can be suppressed even when the amount of ink within the ink pack is changed. 
   According to a third aspect of the present invention, there is provided an ink-jet recording apparatus comprising an ink-jet head and an ink cartridge being vertically mounted. The ink-jet head has an ink ejection face in which a plurality of nozzles that eject ink toward a recording medium are formed. The ink cartridge stores ink to be supplied to the ink-jet head. The ink cartridge includes a housing, an ink pack, and a pressing mechanism that presses the ink pack. The housing is provided with an ink discharge port. The ink pack is disposed within the housing. The pressing mechanism includes a contact and a biasing member. The contact is movably disposed within the housing and in contact with at least a part of the ink pack lower than the ink discharge port. The biasing member biases the contact toward the ink pack in a direction at an angle to a vertical direction. 
   With the foregoing third aspect, since an area on a horizontal plane occupied by the cartridge becomes relatively small, the apparatus as a whole can also be downsized. Moreover, since a variation in pressure applied to the nozzles is suppressed, nozzle meniscus is kept in a proper condition and therefore a good image can be recorded on a recording medium. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other and further objects, features and advantages of the invention will appear more fully from the following description taken in connection with the accompanying drawings in which: 
       FIG. 1  illustrates a general construction of an exemplified ink-jet printer using an ink cartridge according to a first embodiment of the present invention; 
       FIG. 2  schematically illustrates a state where a maintenance operation is performed on a head in the printer of  FIG. 1  as seen from an arrow-II direction; 
       FIG. 3A  is a sectional view of the ink cartridge taken along a line IIIA—IIIA of  FIG. 2 ; 
       FIG. 3B  is a front vies of the ink cartridge as seen from an arrow-B direction of  FIG. 3A : 
       FIG. 3C  is a rear view of the ink cartridge as seen in an arrow-C direction of  FIG. 3A ; 
       FIG. 4A  is a local sectional view taken along a line IVA—IVA of  FIG. 3B ; 
       FIG. 4B  is a local sectional view taken along a line IVB—IVB of  FIGS. 3A and 3B , 
       FIGS. 5A and 53  are schematic sectional views showing how a contact and a coiled spring act depending on the amount of ink in an ink pack in the ink cartridge; 
       FIG. 6  is a front view similar to  FIG. 3B , and shows a first modification of a means for detecting completion of pressing against the ink pack; 
       FIG. 7  is a front view similar to  FIG. 3B , and shows a second modification of the means for detecting completion of pressing against the ink pack: 
       FIG. 8A  is a sectional view similar to  FIG. 3A , and shows a third modification of the means for detecting completion of pressing against the ink pack; 
       FIG. 8B  is a sectional view taken along a line B—B of  FIG. 8A , and shows a state where an F part of  FIG. 8A  is filled up with ink; 
       FIG. 8C  is a sectional view taken along the line B—B of  FIG. 8A , and shows a state where the F part of  FIG. 8A  deflates; 
       FIG. 9A  is a sectional view similar to  FIG. 3A , and shows an ink cartridge according to a second embodiment of the present invention; 
       FIG. 9B  is a schematic sectional view showing a state where an ink pack is filled up with ink; 
       FIGS. 9C and 9D  are sectional views taken along lines C—C and D—D of  FIG. 9A , respectively, and show states of completion of pressing; 
       FIGS. 10A and 10B  are schematic sectional views of an ink cartridge according to a third embodiment of the present invention; and 
       FIGS. 11A and 11B  are schematic sectional views of an ink cartridge according to a forth embodiment of the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   In the following, some preferred embodiments of the present invention will be described with reference to the accompanying drawings. 
   First, referring to  FIGS. 1 and 2 , a description will be given to an example of an ink-jet printer that adopts an ink cartridge according to a first embodiment of the present invention. 
   An ink-jet printer  1  illustrated in  FIG. 1  is a color printer having four ink-jet heads  2 . The printer  1  includes a paper feed unit  11  (as shown lefthand in  FIG. 1 ) and a paper discharge unit  12  (as shown righthand in  FIG. 1 ). Within the printer  1 , formed is a paper conveyance path running from the paper feed unit  11  to the paper discharge unit  12 . 
   A pair of paper feed rollers  5   a  and  5   b  are disposed immediately downstream from the paper feed unit  11 , so that the rollers  5   a  and  5   b  can pinch a paper as a recording medium which is in this condition conveyed from left to right in  FIG. 1 . In a middle of the paper conveyance path, a conveyance unit  13  is provided below the four heads  2  so as to confront the four heads  2 . The conveyance unit  13  has two rollers  6  and  7 , and a looped conveyor belt  8  that is wound on the rollers  6  and  7  to be stretched between them. 
   The conveyor belt  8  has a two-layered structure made up of a polyester base body impregnated with urethane and a silicone rubber. The silicone rubber is adopted on an outer conveyor face side of the conveyor belt  8 . A paper fed through the pair of paper feed rollers  5   a  and  5   b  is pressed on the conveyor face of the conveyor belt  8  to thereby be held onto the conveyor face by adhesive power, and in this condition conveyed downstream, i.e., rightward in  FIG. 1  in association with clockwise rotation (rotation in an arrow- 6   a  direction) of the one roller  6 . 
   Pressing members  9   a  and  9   b  are provided at positions for feeding a paper onto the conveyor belt  8  and for discharging a paper from the conveyor belt  8 , respectively. The pressing members  9   a  and  9   b  serve to press a paper onto the conveyor face in order to prevent a separation of the paper from the conveyor face of the conveyor belt  8 . Thereby, the paper can surely be conveyed on the conveyor face. 
   A peeling plate  10  is provided immediately downstream (rightward in  FIG. 1 ) from the conveyor belt  8 . The peeling plate  10  peels off the paper, which is kept on the conveyor face of the conveyor belt  8  by adhesive power, from the conveyor face so that the paper can be transferred toward the paper discharge unit  12 . 
   Each of the four ink-jet heads  2  has, at its lower end, a head main body  2   a . Each head main body  2   a  has a rectangular section on a plane parallel to a paper conveyance face. The head main bodies  2   a  are arranged close to each other with a longitudinal axis of each head main body  2   a  being perpendicular to a paper conveyance direction, i.e., perpendicular to the drawing sheet of  FIG. 1 . That is, the printer  1  is of line type. Bottom faces of the respective four head main bodies  2   a  confront the paper conveyance path, and a large number of small-diameter nozzles (not illustrated) are arranged on the bottom faces of the four head main bodies  2   a . The bottom face of each ink-jet head  2  is hereinafter referred to as an “ink ejection face”. From the ink ejection faces of the four head main bodies  2   a , ejected are magenta ink, yellow ink, cyan ink, and black ink, respectively. 
   The head main bodies  2   a  are disposed with a narrow clearance being formed between their ink ejection faces and the conveyor face of the conveyor belt  8 . The paper conveyance path is formed through this clearance. With this construction, while a paper, which is being conveyed by the conveyor belt  8 , passes immediately under the four head main bodies  2   a  in order, the respective color inks are ejected through the corresponding nozzles toward an upper face, i.e., a print face, of the paper to thereby form a desired color image on the paper. 
   In a region enclosed by the conveyor belt  8 , a nearly rectangular parallelepiped guide  21  is arranged at a position opposed to the ink-jet heads  2 . The guide  41  is in contact with the back face of the upper part of the conveyor belt  8  to support the upper part of the conveyor belt  8  from inside. The guide  21  has substantially the same width as that of the conveyor belt  8 . 
   The ink-jet printer  1  further comprises a maintenance unit  17  that performs maintenance on the ink-jet heads  2 . The maintenance unit  17  includes a frame  17   a , four purge caps  16 , a purge pump (not illustrated), and the like. The frame  17   a  is movable in a horizontal direction. The four purge caps  16  are supported on the frame  17   a . The purge pump is connected with the respective purge caps  16 . 
   While the ink-jet printer is performing a printing operation, the maintenance unit  17  is disposed in a “withdrawal position”, which in this embodiment locates immediately below the paper feed unit  11 , where the maintenance unit  17  locates lower than the ink-jet heads and never confronts, in a vertical direction, the ink ejection faces  2   b  of the heads  2 . When a predetermined condition is satisfied after completion of the printing operation, the maintenance unit  17  moves in the horizontal direction into a “maintenance position”, which is a position where the conveyance unit  13  exist in  FIG. 1 , where the maintenance unit  17  confronts the ink ejection faces  2   b  of the heads  2  in the vertical direction. Examples of the predetermined condition include a condition that the printer  1  is kept without any printing operation for a predetermined time period, and a condition that the printer  1  is powered off, etc. When the maintenance unit  17  is in the maintenance position, the purge caps  16  cover the ink ejection faces  2   b  of the respective head main bodies  2   a  to thereby avoid drying of the nozzles. 
   The conveyance unit  13  is supported on an elevator mechanism including a chassis  22 , and movable in the vertical direction by means of the elevator mechanism. The chassis  22  that forms the elevator mechanism is put on a cylindrical member  23  disposed thereunder. The cylindrical member  23  is rotatable around a shaft  24  that is deviated from a center of the cylindrical member  23 . Thus, when the shaft  24  rotates, an uppermost level of the cylindrical member  23  varies, and the chassis  22  and the conveyance unit  13  accordingly move up and down. 
   Before the maintenance unit  17  starts moving from the “withdrawal position” into the “maintenance position” as described above, the cylindrical member  23  is rotated through an appropriate angle so that the conveyance unit  13  is, together with the chassis  22 , moved down to an appropriate extent from the position as it is shown in  FIG. 1 . This can provide a space required for a movement of the maintenance unit  17 . 
   Below the maintenance unit  17 , a mounting station  31   a  is provided to hold four ink cartridges  31  (see  FIG. 2 ) being vertically mounted. In the mounting station  31   a , the four ink cartridges  31  are arranged in parallel with one another in the direction perpendicular to the drawing sheet of  FIG. 1   
   Each ink cartridge  31  is detachable from the printer  1  in the paper conveyance direction, i.e., in the direction perpendicular to the drawing sheet of  FIG. 2 . More specifically, each ink cartridge  31  gets mounted on the mounting station  31   a  in an arrow-II direction of  FIG. 1 , headed by its front face having an ink discharge port  32   a . When the ink cartridge  31  is pulled out in a direction reverse to the arrow II, the ink cartridge  31  can be detached from the mounting station  3   a.    
   A handle  30  is formed on a rear face of each ink cartridge  31 , i.e., on a face shown in  FIG. 2  which is a left-side face in  FIG. 1 . Therefore, for attaching and detaching the ink cartridge  31  to and from the mounting station  31   a , a user can easily perform the operation by gripping the handle  30 . 
   Each ink cartridge  31  has a housing  32  made of a synthetic resin, and an ink pack  33  (see  FIGS. 3A ,  3 B, and  3 C) disposed within the housing  32  to store ink that is to be supplied to the head  2 . The four ink cartridges  31  are connected with the respective heads  2  by flexible tubes (not illustrated), so that ink contained in the ink packs  33  can be supplied to the respective heads  2 . 
   Due to a difference in level between the heads  2  and the ink cartridges  31  as illustrated in  FIG. 2 , the heads  2  receive negative pressure immediately after ink is ejected from the ink ejection faces  2   b  of the heads  2 . This negative pressure and capillarity of the nozzles cause suction force that sucks the ink contained in the ink packs  33  into the heads  2 . 
   Then, referring to  FIGS. 3A ,  3 B,  3 C,  4 A, and  4 B, the ink cartridges  31  are described in more detail. 
   As illustrated in  FIG. 3A , the ink cartridge  31  comprises, within the housing  32 , not only the ink pack  33  but also a pressing mechanism  400  having a contact  40  and coiled springs  43 . The coiled springs  43  serve to bias the contact  40  toward the ink pack  33 . An arrow P of  FIGS. 3B and 3C  indicates a direction where the pressing mechanism  400  presses the ink pack  33 . 
   The housing  32  is, as illustrated in  FIGS. 3B and 3C , a substantially parallelepiped hollow member with its vertical length longer than its horizontal width, i.e., than its side extending along a direction perpendicular to the drawing sheet of  FIG. 3A . When the ink cartridge  31  is mounted on the mounting station  31   a , the housing  32  is fixed in a predetermined position by means of an appropriate support member (not illustrated) within the printer  1 . 
   An ink discharge port  32   a  is formed in a front face (i.e., a left-side face in  FIG. 3A ) of the housing  32 . The ink discharge port  32   a  is, as illustrated in  FIG. 3B , formed at a position slightly above a vertical center and deviated from a widthwise center toward a sidewall  32   c  of the housing  32 , toward which the pressing mechanism  400  presses the ink pack  33 . More specifically, the ink discharge port  32   a  is disposed slightly above a portion where an upper end of the contact  40  is positioned after completion of pressing against the ink pack  33 . 
   The ink pack  33  stores ink under a deaerated state. As illustrated in  FIG. 3A , one end of a spout  35  made of a resin is connected to an opening  33   c  of the ink pack  33 , so that ink contained in the ink pack  33  is discharged out of the housing  32  via the spout  35 . 
   As illustrated in  FIGS. 4A and 4B , the spout  35 , which is fitted into the ink discharge port  32   a  of the housing  32 , has one end connected with the opening  33   c  of the ink pack  33  and the other end facing an outside of the housing  32 . In the spout  35 , formed is a through-hole  35   c  extending from the one end to the other end. An opening  35   a  formed at one end of the through-hole  35   c  is smaller than an opening  35   b  formed at the other end of the through-hole  35   c . In addition, as illustrated in  FIG. 4B , the opening  35   a  at one end is, in comparison with the opening  35   b  at the other end, more deviated toward one sidewall  32   c  of the housing  32 , toward which the pressing mechanism  400  presses the ink pack  33 . 
   A cap  37  made of a silicone rubber or a butyl rubber is fitted into the opening  35   b  of the spout  35 , and a hollow needle  38  penetrates through the cap  37 . The hollow needle  38  is provided at an end portion of a flexible tube (not illustrated) that is connected with each of the heads  2 . Thus, ink contained in the ink pack  33  is introduced through the hollow needle  38  into the flexible tube, and then supplied to each head  2 . 
   A replacement of the ink cartridge  31  may be implemented by pulling the hollow needle  38  away from the cap  37  of the waste ink cartridge and then penetrating the hollow needle  38  into a cap  37  of a new ink cartridge. 
   The ink pack  33  is made of a resin film that has been formed by laminating a plurality of flexible films by means of thermo-compression bonding, etc. More specifically, the ink pack  33  has a layered structure made up of an innermost polypropylene layer, a polyester layer acting as a base material, an alumina or silica vapor-deposition layer having a gas barrier function, and a nylon layer for strength improvement, in this sequence from inside to outside. 
   As illustrated in  FIG. 3A , a seal portion  33   a  is provided on an outer surface of the ink pack  33 . The seal portion  33   a  is made of two resin films that are bonded to each other by thermo-compression bonding. By, simultaneously with providing the seal portion  33   a , bonding one end of the spout  35  to the ink pack  33  by thermo-compression bonding, ink leakage through the opening  33   c  of the ink pack  33  can surely be prevented. 
   On a top face of the ink pack  33 , a fold  33   b  is formed along a direction of attachment and detachment of the cartridge (i.e., a right-to-left direction in  FIG. 3A  or a direction perpendicular to the drawing sheet of  FIGS. 3B and 3C ). The fold  33   b  is formed by tucking down a center of the top face of the ink pack  33 . Under a full-ink condition as shown in  FIGS. 3B and 3C , an upper part of the ink pack  33  forms two angular portions. With such a fold formed in the ink pack  33 , the amount of ink charged in the ink pack  33  can be increased. It is hard to charge ink up to the upper part of the ink pack  33  because of the gravity. In this embodiment, however, the fold  33  formed on the top face of the ink pack  33  allows the ink pack  33  to expand throughout both upper corners of the housing  32  so that ink can efficiently charged within the ink pack  33 . 
   The contact  40  is a plate-like member whose lower end is fixed at a position on a bottom face of the housing  32  deviated toward the sidewall  32   c , as shown in  FIGS. 3B and 3C . The contact  40  is rotatable around the lower end thereof. A notch  40   a  is formed at a portion of the contact  40  near to the ink discharge port  32   a  (see  FIG. 3A ). 
   One ends of the respective two coiled springs  43  are connected to a face of the contact  40  opposite to a face thereof contacting with the ink pack  33 . The other ends of the respective coiled springs  43  are connected to a sidewall  32   d  standing opposite to the sidewall  32   c  of the housing  32 . One ends  43   a  of the respective coiled springs  43  are disposed lower than the other ends  43   b  thereof, and therefore the coiled springs  43  can easily be buckled. 
   Within the housing  32 , an interlocker  48  that interlocks with the contact  40  is disposed below the spout  35  and in front of the contact  40  (i.e., on a left side of the contact  40  in  FIG. 3A ) The interlocker  48  is a plate-like member, and the interlocker  48  and the contact  40  are always on the same plane. Similarly to the contact  40 , the interlocker  48  has its lower end fixed at a position on the bottom face of the housing  32  deviated toward the sidewall  32   c , and is rotatable around its lower end. 
   The interlocker  48  is formed integrally with the contact  40  by notching the plate-like member. This enables the interlocker  48  to be efficiently formed without increasing the number of parts. A detection target  48   a  is provided at an upper end of a front face (i.e., on a left side in  FIG. 3A ) of the interlocker  48 . A substantially square-shaped first detection window  32   e  is formed immediately below the ink discharge port  32   a  of the housing  32 . In addition, a reflective photosensor  52  is positioned outside the housing  32  such that it can confront the first detection window  32   e  and such that it can confront the detection target  48   a  under the condition after completion of pressing against the ink pack  33 . The sensor  52  is positioned to confront the front face in which the ink discharge port  32   a  is formed (i.e., positioned on a right side of the cartridge  31  in  FIG. 1 ), in order to avoid interfering with an attachment and detachment of the cartridge. 
   Here, referring to  FIGS. 5A and 5B , a description will be given to how the contact  40  and the coiled springs  43  of the pressing mechanism  400  operate depending on an amount of ink contained in the ink pack  33 . 
   As illustrated in  FIG. 5A , when ink is unused, i.e., the ink pack  33  is filled with ink, the coiled springs  43  are in a buckling state. At this time, the contact  40  is laid in an inclining manner while pressing a lower portion of the ink pack  33  with relatively small force by biasing force of the coiled springs  43 . 
   As a printing operation progresses, an amount of ink in the ink pack  33  decreases by degrees. In association with this, the contact  40  presses the lower portion of the ink pack  33  while rotating around its lower end by biasing force of the coiled springs  43 . When the contact  40  comes into such a position that the coiled springs  43  become unbuckled, biasing force intrinsic in the coiled springs  43  enables the contact  40  to press the ink pack  33  with larger force. 
   Since the contact  40  presses the lower portion of the ink pack  33  in association with its rotation, the ink within the ink pack  33  is gradually gathered upward. The ink gathered in an upper portion of the ink pack  33  is gradually discharged through the spout  35  into the corresponding head  2  by means of suction force that is caused by negative pressure applied to the nozzles of the head  2  and capillarity of the nozzles. 
   Moreover, the ink within the ink pack  33  incurs fluid pressure whose intensity depends upon pressing force applied by the contact  40  and the coiled springs  43 . On the other hand, pressure applied to the nozzles of the head  2  depends mainly upon the fluid pressure arising in the ink within the ink pack  33  and upon a difference in level between the head  2  and the ink cartridge  31 . Accordingly, pressing force applied by the contact  40  and the coiled springs  43  is adjusted in consideration of the difference in level between the head  2  and the ink cartridge  31 , so that pressure to be applied to the nozzles can be kept within a predetermined negative range, −20 mmH 2 O to −80 mmH 2 O in this embodiment, This can suppress such a disadvantage as ink dripping due to broken meniscus which is often caused when positive pressure or excessively small negative pressure, e.g., −10 mmH 2 O, is applied to the nozzles, and moreover this can suppress disadvantages such as ink ejection disability and unstable ink ejection due to air bubbles entering the nozzles which is often caused when excessive negative pressure, e.g., −100 mmH 2 O, is applied to the nozzles. 
   As illustrated in  FIG. 5B , when the coiled springs  43  expand in the horizontal direction, the contact  40  stops in a vertically standing state and completes its pressing against the ink pack  33 . In this embodiment, the coiled springs  43  have such spring characteristics that the amount of ink within the ink pack  33  can reach approximately zero when the contact  40  reaches a rotation limit as shown in  FIG. 5B , i.e., upon completion of the pressing. 
   Upon completion of pressing against the ink pack  33 , the sensor  52  detects the detection target  48   a . This indicates to a user that the pressing against the ink pack  33  has completed. In addition, as described above, since the amount of ink within the ink pack  33  is adjusted such that it can reach approximately zero upon completion of the pressing, the user also recognizes that the amount of ink reaches zero at this time. 
   Although the interlocker  48  rotates together with the contact  40 , the interlocker  48  is away from the ink pack  33  while the contact  40  is pressing the ink pack  33  by biasing force of the coiled springs  43 . Therefore, since the interlocker  48  is prevented from contacting with the ink pack  33  and thus from interfering with the pressing operation, pressing against the ink pack  33  can smoothly be performed and, at the same time, completion of pressing can exactly be detected. 
   Moreover, by detecting a position of the detection target  48   a , the amount of ink within the ink pack  33  can be recognized. Since, in this embodiment, the detection target  48   a  is positioned away from a center of rotation of the interlocker  48 , the detection target  48   a  moves to a larger extent while the ink pack  33  changes from a full-ink state to an approximately zero-ink state. This enables the amount of ink to be detected with improved accuracy. 
   As illustrated in  FIGS. 3A and 3C , a second detection window  32   b  is formed in a rear face of the housing  32  (i.e., in a right-side face in  FIG. 3A ). The second detection window  32   b  is longer in a transverse direction than the first detection window  32   e , and formed across a substantially entire width of the housing  32 . An upper end portion of the interlocker  48  appears in the first detection window  32   e  only around the time of completion of the pressing against the ink pack  33 , while a part of the upper end of the contact  40  always appears in the second detection window  32   b . As illustrated in  FIG. 1 , when the ink cartridges  31  are mounted on the mounting station  31   a , the rear faces of the respective cartridges  31  are exposed to an outside of the printer  1  and therefore an user can readily make visual observation thereof. Therefore, instead of any special detection means such as sensors, the user can visually observe the contact  40  from the outside through the second detection window  32   b , and recognize a position of the contact  40 , which indicates to the user not only whether pressing is completed but also a rough amount of ink remaining within the ink pack  33 . In addition, when a scale that indicates the amount of ink is marked at the upper end portion of the rear face of the contact  40 , the amount of ink can be recognized more exactly. 
   According to the ink cartridge  31  of this embodiment, as described above, an area on a horizontal plane occupied by the cartridge  31  becomes smaller as compared with an ink cartridge being horizontally mounted or comprising a housing with no wall vertically long. Moreover, since the above-described pressing mechanism  400  including the contact  40  and the coiled springs  43  is provided, a variation in pressure applied to the nozzles can be suppressed even when the amount of ink within the ink pack  33  is changed. 
   According to the printer  1  using the ink cartridge  31  of this embodiment, further, since the area on the horizontal plane occupied by the cartridge  31  becomes relatively small, the printer  1  as a whole can also be downsized. In addition, since a variation in pressure applied to the nozzles is suppressed, nozzle meniscus is kept in a proper condition and therefore stable ejection characteristics can be obtained. Consequently, a good image can be recorded on a paper. 
   The pressing force applied by the contact  40  and the coiled springs  43  is adjusted in consideration of the difference in level between the head  2  and the ink cartridge  31 , so that pressure to be applied to the nozzles can be set at a predetermined value. This can provide an improved variance in design of how to arrange the head  2  and the ink cartridges  31 . For example, there can be adopted such a layout that, as in this embodiment, the mounting station  31   a  for the ink cartridges  31  locates below the withdrawal position in order to provide the withdrawal position of the maintenance unit  17 . 
   The contact  40  of this embodiment is rotatable around its lower end. Therefore, appropriate pressing force can be applied to the ink pack  33  depending on the amount of ink within the ink pack  33 , so that the variation in pressure applied to the nozzles can effectively be restrained. 
   Furthermore, the coiled springs  43  stay buckled when ink is unused. Accordingly, when the ink pack  33  is filled with ink and therefore internal pressure, i.e., ink discharge pressure through the ink discharge port  32   a , is sufficiently high, the pressing force applied to the ink pack  33  can be kept small. Then, as the ink within the ink pack  33  decreases to lower the internal pressure of the ink pack  33 , the pressing force applied to the ink pack  33  can be increased. Like this, by varying the pressing force in accordance with a change in amount of ink within the ink pack  33 , the pressure applied to the nozzles can always be kept within a predetermined range. Moreover, when there is a large amount of ink within the ink pack  33 , no excessive pressing force is applied to the ink pack  33 . As a result, a larger amount of ink can be charged into the ink pack  33 . 
   Since the ink discharge port  32   a  is disposed near a portion where the upper end of the contact  40  is positioned after completion of pressing against the ink pack  33 , the ink within the ink pack  33  can, in association with the pressing, smoothly be flown into the ink discharge port  32   a  and discharged therefrom. This can economically reduce an amount of ink unusedly remaining within the ink pack  33 . 
   The position of the ink discharge port  32   a  deviated toward the sidewall  32   c , toward which the pressing mechanism  400  presses the ink pack  33 , can also provide the aforementioned effect, i.e., the effect that the ink within the ink pack  33  can smoothly be discharged from the ink discharge port  32   a.    
   In this embodiment, particularly, the housing  32  forms a rectangular cylinder, the contact  40  presses the ink pack  33  while moving toward the sidewall  32   c  of the housing  32  by biasing force of the coiled springs  43 , and the ink discharge port  32   a  is provided to be deviated toward the sidewall  32   c . With this construction, the pressing against the ink pack  33  can be performed efficiently because the ink pack  33  is sandwiched between the contact  40  and the sidewall  32   c  of the housing  32 , and at the same time the ink within the ink pack  33  can smoothly be discharged from the ink discharge port  32   a . This can provide the same effect as mentioned above that a reduced amount of ink remains within the ink pack  33 . 
   The notch  40   a  is formed at a portion of the contact  40  near to the ink discharge port  32   a . If a contact having no notch  40   a  were used to press the ink pack  33 , its portion corresponding to the notch  40   a  would interfere with inkflow that runs toward the ink discharge port  32   a  and thus ink could not be discharged smoothly. In this embodiment, on the contrary, since the notch  40   a  is formed, ink flowing toward the ink discharge port  32   a  has its passage resistance restrained and the ink can smoothly flow toward the ink discharge port  32   a  to be discharged therefrom. Therefore, the presence of the notch  40   a  can also provide the same effect as mentioned above that a reduced amount of ink remains within the ink pack  33 . 
   In this embodiment, further, the spout  35  is connected to the ink discharge port  32   a , and the opening  35   a  formed at one end of the spout  35  connected with the opening  33   c  of the ink pack  33  is more deviated toward the sidewall  32   c , toward which the pressing mechanism  400  presses the ink pack  33 , as compared with the opening  35   b  formed at the other end of the spout  35 . Since, like this, the opening  35   a  at one end connected with the opening  33   c  of the ink pack  33  is deviated toward the sidewall  32   c , ink can smoothly flow from the opening  33   c  of the ink pack  33  to the opening  35   a  of the spout  35 . The ink is then discharged through the through-hole  35   c  of the spout  35  into the outside of the housing  32 . This can provide the effect that a reduced amount of ink remains within the ink pack  33 . 
   Next, with reference to  FIGS. 6 ,  7 ,  8 A,  8 B, and  8 C, a description will be given to modifications of a means for detecting completion of pressing against the ink pack  33 . Here, the same members as in the above-described embodiment will be denoted by the common reference numerals, and descriptions thereof will be omitted. 
   A first modification as illustrated in  FIG. 6  differs from the first embodiment in constructions of an interlocker and a first detection window. No detection target  48   a  is provided at an upper end of an interlocker  49 , but a protrusion  49   a  protruding toward a front side (vertically upward from the drawing sheet of  FIG. 6 ) is formed. A first detection window  32   f  is longer in a transverse direction than the detection window  32   e  of  FIG. 3B , and shaped in conformity with a track on which an upper end portion of the interlocker  49  travels during its rotation, so that the protrusion  49   a  of the interlocker  49  can always protrude beyond the detection window  32   f . A leaf switch  53  is disposed at an end of the detection window  32   f  on the pressing direction P side, i.e., disposed at a position into which the upper end of the interlocker  49  comes when pressing is completed. 
   Upon completion of pressing against an ink pack  33 , the protrusion  49   a  of the interlocker  49  comes in contact with a lever  53   a  of the leaf switch  53  to thereby operate the leaf switch  53 . This informs a user of completion of pressing against the ink pack  33 . 
   In this modification, differently from the detection window  32   e  of the first embodiment, the first detection window  32   f  formed in a front face of the housing  32  has such a configuration that the protrusion  49   a  of the interlocker  49  can always protrude beyond the first detection window  32   f . Accordingly, instead of any special detection means such as sensors, an user can visually observe the protrusion  49   a  of the interlocker  49  from the outside through the first detection window  32   f , and thereby recognize a position of the contact  40 , which indicates to the user not only whether pressing against the ink pack  33  is completed but also a rough amount of ink remaining within the ink pack  33 . 
   A second modification as illustrated in  FIG. 7  is almost the same as the first modification of  FIG. 6 , but detects a protrusion  49   a  by means of, instead of the leaf switch  53 , a transmissive photosensor  54 . Upon completion of pressing against an ink pack  33 , the protrusion  49   a  comes between an upper detector  54   a  and a lower detector  54   b  of the transmissive photosensor  54  and is detected in this state. This informs a user of completion of pressing against the ink pack  33 . 
   In a third modification illustrated in  FIGS. 8A to 8C , an ink amount detector  71  is further included in the housing  32 . The ink amount detector  71  and the contact  40  are separate members, and the ink amount detector  71  displaces in accordance with an amount of ink within an ink pack  33 . The ink amount detector  71  is, as illustrated in  FIG. 8A , disposed above a notch  40   a  of the contact  40  in such a manner as to incline upward toward a front side. 
   As illustrated in  FIGS. 8B and 8C , the ink amount detector  71  is, in a plan view, an elongated plate-like member bent into V-shape. The ink amount detector  71  is rotatable around a shaft  74   a . A rotation supporter  74  is secured to a sidewall  32   d  of the housing  32 , and the shaft  74   a  is mounted on the rotation supporter  74 . On a side of the bent portion of the ink amount detector  71  slightly near to its rear end  71   b , integrally formed is a bracket  71   c  that is rotatably supported on the shaft  74   a.    
   A coiled spring  72  is wound around a circumference of the shaft  74   a . One end of the coiled spring  72  is in contact with the sidewall  32   d  of the housing  32 , and the other end thereof is in contact with a vicinity of the rear end  71   b  of the ink amount detector  71 . Thus, the coiled spring  72  biases the vicinity of the rear end  71   b  of the ink amount detector  71  toward the ink pack  33  side by use of reaction force received from the sidewall  32   d  of the housing  32 . As a result, the vicinity of the rear end  71   b  of the ink amount detector  71  can always be in contact with a side face of the ink pack  33  near to an ink discharge port  32   a.    
   As illustrated in  FIG. 8A , the housing  32  has an opening  73  formed above the ink discharge port  32   a . A front end  71   a  of the ink amount detector  71  protrudes beyond the opening  73 . As illustrated in  FIGS. 8B and 8C , the opening  73  is formed across a substantially entire width of the housing  32 , and has an elongated shape with its length corresponding to a range within which the front end  71   a  of the ink amount detector  71  travels during its rotation. Therefore, the front end  71   a  of the ink amount detector  71  always protrudes beyond the opening  73 . 
   Here will be explained how the pressing mechanism  400  and the ink amount detector  71  operate in accordance with the amount of ink within the ink pack  33 . 
   In the above-described first embodiment, spring characteristics of the coiled springs  43  are adjusted such that the amount of ink within the ink pack  33  can reach approximately zero upon completion of pressing by the pressing mechanism  400 . In this modification, alternatively, spring characteristics of the coiled springs  43  are adjusted such that the pressing mechanism  400  can complete its pressing operation before the amount of ink within the ink pack  33  reaches approximately zero. 
   When the contact  40  rotates halfway and a certain amount of ink remains within the ink pack  33 , a portion of the ink pack  33  enclosed with a dotted line in  FIG. 8A  (hereinafter referred to as an “F portion”) is kept filled up with ink. This is because, as mentioned above, the ink within the ink pack  33  is, in association with rotation of the contact  40  having the notch  40   a , gathered upward especially around the ink discharge port  32   a .  FIG. 8B  illustrates this state. 
   Subsequently, when the contact  40  rotates on up to its rotation limit and completes pressing against the ink pack  33 , most of the ink within the ink pack  33  is gathered around the F portion. The ink gathered around the F portion is discharged through the ink discharge port  32   a , and the F portion accordingly becomes deflated by degrees. In association with this, biasing force of the coiled spring  72  forces the ink amount detector  71  to rotate counterclockwise in a plan view, so that the front end  71   a  moves from its position shown in  FIG. 8B  into a position shown in  FIG. 8C . 
   According to this modification, as described above, since the front end  71   a  protrudes beyond the opening  73 , completion of pressing can easily be detected by employing, e.g., the leaf switch of  FIG. 6  and the transmissive photosensor  54  of  FIG. 7 . 
   Moreover, by detecting a position of the front end  71   a , the amount of ink within the ink pack  33  can be recognized. A desired detection accuracy can be obtained by properly sharing a whole length of the ink amount detector  71  between a distance from a center of rotation to the front end  71   a  and a distance from the center to the rear end  71   b.    
   Further, since the ink amount detector  71  and the contact  40  are separated members that are independent of each other, spring characteristics of the coiled springs  43  can be adjusted with an improved variance as compared with the above-described first embodiment. In the first embodiment, the amount of residual ink is detectable based on the positions of the contact  40  and the interlocker  48 . Therefore, spring characteristics of the coiled springs have to be adjusted such that the positions of the contact  40  and the interlocker  48  can correspond to the amount of residual ink. In this modification, on the other hand, the amount of residual ink is detectable based on the position of the ink amount detector  71  that is a separated member from the contact  40 . Therefore, spring characteristics of the coiled springs  43  for biasing the contact  40  can properly be adjusted. Consequently, spring characteristics of the coiled springs  43  can be increased to a proper extent, for stabilization of pressing force by the pressing mechanism  400 . 
   In this modification, since completion of pressing against the ink pack  33  and/or the amount of ink within the ink pack  33  are detected based on the ink amount detector  71 , there is no need of the interlocker  48  and the first detection window  32   e  of the first embodiment, which are therefore omitted from  FIGS. 8A to 8C . 
   Next, referring to  FIGS. 9A ,  9 B,  9 C, and  9 D, a description will be given to an ink cartridge according to a second embodiment of the present invention. Here, the same members as in the above-described embodiment will be denoted by the common reference numerals, and descriptions thereof will be omitted. 
   As seen from  FIGS. 9A and 3A , an ink cartridge  131  of this embodiment comprises a contact  140  that is different from the contact of the first embodiment. The other members are the same as in the first embodiment, so the ink cartridge  131  is also applicable to the ink-jet printer  1 . 
   The contact  140  has an upper contact portion  104  and a lower contact portion  40 . The upper contact portion  104  and the lower contact portion  40  contact with an upper part and a lower part of an ink pack  33 , and, by biasing force of the coiled springs  43 , press the upper and lower part of the ink pack  33 , respectively. 
   The lower contact portion  40  has substantially the same construction as that of the contact of the first embodiment. That is, the lower contact portion  40  is a plate-like member whose lower end is fixed at a position on a bottom face of a housing  32  deviated toward the sidewall  32   c  (see  FIG. 3B ). The lower contact portion  40  is rotatable around the lower end thereof, and biased toward the ink pack  33  by the coiled springs  43 . 
   The upper contact portion  104  is, as illustrated in  FIG. 9A , a rectangular plate-like member whose length is substantially the same as an upper edge of the lower contact portion  40 . The upper contact portion  104  is connected to the upper edge of the lower contact portion  40 , via two cylindrical rollers  104   a  and  104   b , at a variable angle to the lower contact portion  40 . In the middle of a lower edge of the upper contact portion  104 , a protrusion  104   c  protruding downward is formed between the rollers  104   a  and  104   b.    
   Here will be described how the contact  140  operates in accordance with the amount of ink within the ink pack  33 . 
   When the ink pack  33  is filled up with ink, the lower contact portion  40  is laid in an inclining manner, and the upper contact portion  104  is laid along the vertical direction and sandwiched between the ink pack  33  and a sidewall  32   d  of the housing  32 , as illustrated in  FIG. 9B . 
   As the amount of ink within the ink pack  33  decreases by degrees, the lower contact portion  40  rotates around its lower end in the pressing direction P. On the other hand, the upper contact portion  104  is kept standing vertically. 
   Then, as illustrated in  FIG. 9C , the coiled springs  43  expand in the horizontal direction, and the lower contact portion  40  stands in the vertical direction. Simultaneously, the protrusion  104   c  of the upper contact portion  104  is brought into contact with a surface of the lower contact portion  40 , so that both the upper contact portion  104  and the lower contact portion  40  press the ink pack  33  in a vertically standing manner by biasing force of the coiled springs  43 . The upper contact portion  104  presses a region of the upper part of the ink pack  33  except for a portion above a notch  40   a , i.e., except for an F portion, by biasing force of the coiled springs  43 . Therefore, most of the ink within the ink pack  33  is gathered into the F portion of  FIG. 9A  (see  FIG. 9D ), and then gradually discharged through an ink discharge port  32   a.    
   According to the ink cartridge  131  of this embodiment, as described above, since the upper contact portion  104  and the lower contact portion  40  press the upper part and the lower part of the ink pack  33  by biasing force of the coiled springs  43 , a pressed region of the ink pack  33  is larger than that of the first embodiment. This can economically reduce an amount of ink unusedly remaining within the ink pack  33 . 
   The amount of ink within the ink pack  33  can be detected using, instead of the detection target  48   a  of the interlocker  48  and the reflective photosensor  52 , the leaf switch  53  of  FIG. 6 , the transmissive photosensor  54  of  FIG. 7 , the ink amount detector  31  of  FIGS. 8A to 8C , or combinations thereof. 
   Then, referring to  FIGS. 10A and 10B , an ink cartridge according to a third embodiment of the present invention will be described. Here, the same members as in the above-described embodiment will be denoted by the common reference numerals, and descriptions thereof will be omitted. 
   An ink cartridge  231  of this embodiment comprises a contact  240  that, differently from the contacts of the above-described embodiments, does not rotate and is movable along a width of the cartridge  231 , i.e., along an arrow-Q direction in  FIG. 10A . The other members are the same as in the first embodiment, so the ink cartridge  231  is also applicable to the ink-jet printer  1 . 
   The contact  240  moves, by biasing force of the coiled springs  43 , in the arrow-Q direction while standing in the vertical direction, and thereby presses a lower part of an ink pack  33 . The contact  240  is not fixed onto a bottom face of a housing  32 , but supported by coiled springs  43  whose biasing force allows a movement of the contact  240 . The contact  240  has a notch  240   a  that is similar to the notch of the first embodiment. 
   This embodiment provides the same effect as that of the first embodiment that an amount of ink unusedly remaining within the ink pack  33  can be reduced, because the contact  240  presses the lower part of the ink pack  33  by biasing force of the coiled springs  43 . 
   Then, with reference to  FIGS. 11A and 11B , an ink cartridge according to a forth embodiment of the present invention will be described. Here, the same members as in the above-described embodiment will be denoted by the common reference numerals, and descriptions thereof will be omitted. 
   An ink cartridge  331  of this embodiment comprises two pairs of contact  40  and coiled springs  43  of the first embodiment. In addition, an ink discharge port  132   a  formed in a front face of a housing  132  is disposed substantially at a widthwise center, which is different from the above-described embodiments. The other members are the same as in the first embodiment, so the ink cartridge  331  is also applicable to the ink-jet printer  1 . 
   The contacts  40  and the coiled springs  43  are disposed on both right and left sides of a lower part of an ink pack  33 . A lower end of each contact  40  is fixed about a widthwise center of a bottom face of the housing  132 . Each contact  40  is rotatable around its lower end. 
   When the ink pack  33  is filled up with ink, the two contacts  40  press the lower part of the ink pack  33  from both right and left sides of the ink pack  33  while symmetrically disposed in an inclining manner. Each of the contacts  40  is biased by the coiled springs  43 . 
   As the amount of ink within the ink pack  33  decreases, the two contacts  40  rotate and get closer to each other. Subsequently, when the coiled springs  43  expand in the horizontal direction, the contacts  40  stop their rotation in a vertically-standing state, and completes pressing against the ink pack  33 . At this time, the two contacts  40  sandwich the lower part of the ink pack  33  from both right and left sides thereof, and the ink within the ink pack  33  is gathered upward. 
   According to this embodiment, since the lower part of the ink pack  33  is pressed from its both sides, the ink within the ink pack  33  can be efficiently gathered upward and smoothly flown into the ink discharge port  132   a  to be discharged therefrom. Therefore, an amount of ink unusedly remaining within the ink pack  33  can advantageously be reduced. 
   The fold  33   b  can be formed not only on the top face of the ink pack  33  but also at any other suitable positions, or alternatively the ink pack  33  may lack a fold. 
   A biasing member that biases the contact is not limited to the coiled spring  43 , but other elastic members, etc., can be employed as long as the members can bias the contact toward the ink pack. In addition, the coiled spring  43  may not necessarily stay buckled when ink is unused. 
   It is not always required that the ink discharge port  32   a  or  132   a  is disposed near a portion where the upper end of the contact  40  is positioned after completion of pressing against the ink pack  33 , but it can be disposed at any other suitable positions. 
   In the first embodiment, the opening  35   a  formed at one end of the spout  35  is, in comparison with the opening  35   b  formed at the other end thereof, more deviated toward the sidewall  32   c  of the housing  32 . However, this is not limitative. 
   The notch  40   a  may not be formed at the portion of the contact  40  near to the ink discharge port  32   a.    
   Although, in the first and second embodiments, the detection target  48   a  is positioned away from the center of rotation of the interlocker  48 , the detection target  48   a  can be positioned at any suitable position. 
   Moreover, the interlocker  48 , which is formed integrally with the contact  40  in the embodiments, can be separate from the contact  40 . The interlocker  48  is not an essential element but can be omitted. The means  52 ,  53 , and  54  for detecting the interlocker  48  can also be omitted. 
   It is not necessary to provide a special detection means for detecting completion of pressing by the pressing mechanism  400  or for detecting the position of the contact  40 . 
   It is not necessary to form an opening, such as the second detection window  32   b  formed in the rear face of the housing  32 , which enables the contact  40  to be visually observed from the outside. 
   The ink cartridge of the present invention can be applied to both line-type and serial-type ink-jet printers. 
   Further, an application of the present invention is not limited to ink-jet printers. The present invention is also applicable to, for example, ink-jet type facsimile machines or copying machines. 
   While this invention has been described in conjunction with the specific embodiments outlined above, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the preferred embodiments of the invention as set forth above are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the invention as defined in the following claims.