Abstract:
The present invention relates to a cartridge for supplying fluid to an ink jet nozzle. The fluid or ink level of the cartridge is indicated by a visualization through a transparent plate and has a scale to facilitate the determination of remaining ink in the cartridge. The cartridge additionally possesses features which allow ink to be guided and collected into a recess thereby reducing the amount of residual ink which remains in a cartridge.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an apparatus for supplying fluid to an ink jet nozzle. In particular, this invention relates to a tall, narrow, rectangular cartridge formed with a recess in the inner base so as to eliminate residual ink left therein. 
     2. Description of Prior Art 
     “Ink-jet printer with user replaceable printing system cartridge”, disclosed in U.S. Pat. No. 4,831,389, provides a rigid ink container supplying ink to the nozzle. Owing to the geometrical structure of the ink container, the ink cannot be entirely transmitted to the nozzle. thus, a volume of the ink is left as residue. Erickson et al discloses a trapezoidal ink container to eliminate the residual ink left therein. However, it is not easy to remove the trapezoidal container from the printer. Although a flat ridge cartridge with lunate structure, disclosed in “Ink jet printer incorporating high volume reservoirs”, U.S. Pat. No. 5,686,947, can eliminate the residual ink, the replacement of the cartridge is inconvenient and the user cannot determine the actual volume of ink left in the cartridge at a given moment. “Continuous Refill of spring bag reservoir in an ink jet swath printer/plotter” disclosed in U.S. Pat. No. 5,745,137 and “Negative pressure ink delivery system” disclosed in U.S. Pat. No. 5,757,406, respectively provide a flat and flexible ink bag to store the ink. However, the user also cannot tell the actual volume of ink left in the flexible bag from the outside. 
     SUMMARY OF THE INVENTION 
     To solve the above problem, the primary object of this invention is to provide a cartridge for supplying ink to a jet nozzle and leaving minimum residual ink therein. The present invention comprises a reservoir with a tall, narrow, rectangular structure for storing the ink and a transmitting device having a duct disposed in the reservoir so as to transmit the ink to the ink jet. A transparent panel disposed on the reservoir is used to indicate the volume of the ink left therein. The tall-narrow rectangular reservoir has an inner base that is composed of a primary surface and a secondary surface. In comparison with the level ink, the secondary surface is lower than the primary surface. Therefore, the residual ink left on the primary surface can be gathered and guided to the secondary surface. 
     The present invention is characterized in that a recess (rectangular, trapezoidal, triangular, or a semi-spherical) with a secondary surface is formed next to the primary surface, and the opening of the duct is disposed in the recess. The residual ink left on the primary surface can therefore be finally gathered and guided into the recess. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention can be more fully understood by reading the subsequent detailed description and examples with reference made to accompanying drawings in which: 
     FIG. 1 is a perspective diagram showing the structure of a plotter; 
     FIG. 2A is a perspective diagram showing the structure of a set of cartridges received together in a case according to the present invention; 
     FIG. 2B is an exploded perspective diagram showing the structure of the cartridges and the case according to FIG. 2A; 
     FIG. 3A is a perspective diagram showing the structure of the cartridge of the present invention; 
     FIG. 3B is an exploded perspective diagram showing a duct separated from the cartridge; and 
     FIGS. 4A,  4 B,  4 C are three perspective diagrams respectively showing three types of recesses formed on the bottom of a cartridge, wherein: 
     FIG. 4A shows a trapezoidal recess; 
     FIG. 4B shows a triangular recess; and 
     FIG. 4C shows a semi-spherical recess. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, a perspective diagram shows the structure of a plotter  1 . The plotter  1  comprises a frame structure  10 , a guiding bar  11  mounted on the frame structure  10 , a set of ink jet heads  12  reciprocally movable along the bar  11 , a control device  13  installed on the frame structure  10  and a seat  14  for receiving an ink source  2 . The ink source  2  is a replaceable element communicated with each ink jet  10  with a flexible tube  15  and used to supply the ink to the ink jet heads  10 . The control device  13  controls the movement of the ink jet  10  and the flow rate of the ink outputted from the ink source  2 . 
     FIG. 2A is a perspective diagram showing the assembly structure of the ink source  2  and FIG. 2B is an exploded view according to FIG.  2 A. 
     Referring to FIG. 2B, the ink source  2  comprises a set of cartridges  3  spaced with each other and together received in a case  4 . Each cartridge  3  is provided with two openings  301 ,  302  used to be an entrance for a duct  5  and a vent (sealed by a plug  303 ), respectively. 
     The case  4  is formed with several longitudinal slots  40  spaced apart from each other by division plates  411 ,  412 ,  413 ,  414 ,  415 ,  416 ,  417  and used to receive cartridges  20 , respectively. Pairs of spaced clamps  401 ,  402  are formed on the top surface  400  of the case  4  in alignment with the slots  40 , and each pair of clamps  401 ,  402  is used to clamp the duct  5 . Notches  411 N,  412 N,  413 N,  414 N,  415 N,  416 N,  417 N are respectively formed on the end portion of each of the plates  411 - 417 , and any two of these notches  411 N- 417 N are asymmetrical to each other. Each cartridge  3  is provided with a protrusion  34  formed on the sidewall of the cartridge  3  (as shown in FIG.  3 A). When placed in the destined slot  40 , the cartridge  3  fits into only one of the notches  411 N- 417 N. This is a so-called “idiot-proof design” applied on the present invention so as to prevent the destined cartridge  3  from being placed in the wrong slot  40 . 
     Referring to FIG.  3 A and FIG. 3B, FIG. 3A is a perspective diagram showing the structure of the cartridge  3  and FIG. 3B is an exploded view showing the duct  5  separated from the cartridge  3 . 
     The cartridge  3  has a container  30  serving as a reservoir to store the ink  6 , and the duct  5  extended into the container  30  is merged in the ink  6 . The container  30 , formed in a shape of tall, narrow, rectangular structure, comprises a top plate  304 , two side plates  305 , a front plate  306 , a rear plate  307  and a bottom plate  308 . The openings  301 ,  302  are formed on the top plate  304  and the protrusion  34  is formed on one side plate  305 , and a scale  33  with numbers is noted on the front plate  305  according the inner volume of the container  30 . The front plate  306  is a transparent plate made of acryl resin or other transparent material, so that the user can tell outside the volume of the ink  6  stored in the container  30 . In addition, the container  30  has an inner base  31  composed of a primary surface  311  and a secondary surface  312 . The primary surface  311  and the secondary surface  312  are next to each other with a height difference H, i.e. the primary surface  311  has a depth H 2  and the secondary surface  312  has a depth H 2  with respect to the level  60  of the ink  6 . In other words, a rectangular recess  32  is formed in the inner base  31  next to the primary surface  311 , and the secondary surface  312  is the bottom of the rectangular recess  32 . The opening  50  of the duct  5  is disposed facing on the secondary surface  312 . 
     The duct  5  drains the ink  6  out off the cartridge  3 . When the ink level  60  first reaches the primary surface  311 , part of ink  6  still remains on the primary surface  311 . When the ink level  60  is about to be lower than the primary surface  311 , the residual ink left on the primary surface  311  is induced to and accumulated in the recess  32  by its cohesive force. Finally, the ink  6  gathered in the recess  32  can be sucked up by the duct  5 . 
     FIGS. 4A,  4 B,  4 C are three perspective diagrams showing three types of recesses  32 - 1 ,  32 - 2 ,  32 - 3  formed on each bottom of the three cartridges  3 - 1 ,  3 - 2 ,  3 - 3 , respectively. As mentioned above, the recess  32  is rectangular (or cylindrical) having the secondary surface  322  below the primary surface  311 . The recess  32 - 1  is trapezoidal having an inner surface  312 - 1  below the primary surface  311 . The recess  32 - 2  is triangular having a slanted surface  312 - 2  below the primary surface  311 . The recess  32 - 3  is semi-spherical having an inner surface  312 - 3  below the primary surface  311 . Each duct  5  disposed in the cartridges  3 - 1 ,  3 - 2 ,  3 - 3  can easily drain the ink  6  to the jet nozzle  12  from the recesses  32 ,  32 - 1 ,  32 - 2 ,  32 - 3 , and the residual ink left on the primary surface  311  can completely and naturally flow to the recesses. 
     By converting the inner volume of the container  30  into a series numbers noted on the transparent plate  306  (a narrow-tall side), the volume of the ink  6  above the primary surface  311  and the secondary surface  312  can be clearly shown outside and indicated by these number. 
     While this invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.