Patent Publication Number: US-6910763-B2

Title: Ink storage unit

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is a divisional of a prior application Ser. No. 10/064,611, filed Jul. 31, 2002, now U.S. Pat. No. 6,817,706 which claims the priority benefit of Taiwan application serial no. 91208003, filed on May 31, 2002. 

   BACKGROUND OF INVENTION 
   1. Field of the Invention 
   The invention relates generally to an ink storage unit and, more particularly, to an ink storage unit that can prevent reverse ink flowing causing ink leakage. 
   2. Description of the Related Art 
   Due to its advanced development, inkjet printing technology is broadly implemented in many types of printing apparatuses such as printers or facsimile machines. Inkjet printing technology principally consists of an inkjet print head that produces a high pressure to eject ink droplets out of the print head on the printed document, thereby forming an ink point thereon. By an adequate disposition of the numerous ink points on the printed documents, characters or graphics hence are formed. To continuously supply the inkjet print head with ink, an ink storage unit is traditionally used to store ink. 
   To prevent ink leakage out of the ink storage unit, a method of the prior art uses a pressure regulator that is disposed within an ink tank of the ink storage unit. The pressure regulator adequately regulates a pressure differential between the interior and the exterior of the ink tank by creating a negative pressure that keeps the ink from leaking out. Another method known in the prior art is to arrange an ink storage body made of porous material such as sponge or fabric within the ink tank. Via capillary action of the porous ink storage body, the ink can be stored and retained within the ink tank. 
     FIG. 1  is a sectional view that schematically illustrates the construction of an ink storage unit known in the prior art. As illustrated, a traditional ink storage unit  100  principally comprises an ink tank  110  that defines a confinement space  112  in which an ink storage body  120  is placed. The ink storage body  120  is made of a porous material such as sponge that enables to store and retain ink within the ink tank  110  by capillary action. The ink tank  110  further includes an ink outlet  114  at a lower side to output ink to an ink-ejecting member  300 . An upper side of the ink tank  110  is further provided with an air inlet  116  through which air is enabled to penetrate the confinement space  112  of the ink tank  110 . While the ink is outputted through the ink outlet  114 , the external air simultaneously penetrates into the ink tank  110  through the air inlet  116  so as to achieve an adequate pressure balance of the confinement space  112  with respect to the external pressure. Ink output through the ink outlet  114  can be thereby sustained to supply the ink-ejecting member  300 . 
   The introduction of ink within the ink tank  110  is usually achieved via ink injection by means of a syringe inserted through the air inlet  116  to the lower half of the ink storage body  120 . However, ink stored in the ink storage body  120  may flow along the interface  130  between the outer surface of the ink storage body  120  and the inner sidewall of the ink tank and leak out through the air inlet  116 . Therefore, the prior art further disposes a notch  121  on the outer surface of the ink storage body  120  facing the air inlet  116 . The outer surface of the ink storage body  120  at that location is thereby separated a higher distance from the air inlet  116 . Ink flowing through the interface  130  thus cannot contact with the air inlet  116  at the location of the notch  121  and, consequently, ink leakage is prevented. 
   However, the above disposition becomes deficient when the ink storage unit  100  is subject to significant external shaking, and ink leakage through the air inlet  116  hence still occurs. 
   SUMMARY OF INVENTION 
   An aspect of the invention is therefore to provide an ink storage unit that can effectively prevent ink leakage through the air inlet. 
   To accomplish the above and other objectives, an ink storage unit of the invention comprises an ink tank that defines an inner confinement space in which is placed an ink storage body to store and retain ink. The ink tank respectively includes an air inlet through which air passage into the ink tank is enabled, and an ink outlet through which ink output is achieved. The ink storage body is comprised of a first end portion approximately close to the air inlet and a second end portion approximately close to the ink outlet and relatively farther from the air inlet. An outer surface of the ink storage body includes a plurality of notches distributed along an interface between the ink storage body and the ink tank, thereby forming a plurality of gaps that locally separate the outer surface of the ink storage body from the sidewall of the ink tank to cut off ink flowing there along. 
   In accordance with the above objectives of the invention, the ink storage body is alternatively comprised of a first ink storage portion separated from a second ink storage portion via a spacing member. The first ink storage portion is placed approximately close to the air inlet and the second ink storage portion is placed approximately close to the ink outlet and relatively farther from the air inlet. The spacing member creates a spacing gap between the first and second ink storage portions so that reverse ink flowing causing ink leakage through the air inlet is prevented. 
   It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
     The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
       FIG. 1  is a sectional view illustrating a traditional ink storage unit of the prior art. 
       FIG. 2  is a sectional view illustrating an ink storage unit according to an embodiment of the invention. 
       FIG. 3  is a sectional view illustrating an ink storage unit according to another embodiment of the invention. 
   

   DETAILED DESCRIPTION 
   The following detailed description of the embodiments and examples of the present invention with reference to the accompanying drawings is only illustrative and not limiting. Wherever possible in the following description and accompanying drawings, like reference numerals and symbols will refer to like elements and parts unless otherwise described. 
   Referring to  FIG. 2 , a sectional view schematically illustrates the construction of an ink storage unit according to an embodiment of the invention. As illustrated, an ink storage unit  200  of the invention principally comprises an ink tank  210  that defines an inner confinement space  212  in which is disposed an ink storage body  220 . The ink storage body  220  is preferably made of a porous material such as sponge or fabric. The inner pores of the ink storage body  220  are used to absorb and retain ink by capillary action. A lower side of the ink tank  210  is provided with an ink outlet  214  through which the ink is conducted out of the confinement space to an ink-ejecting member  300 . An upper side of the ink storage unit  200  is further provided with an air inlet  216  through which an external air is enabled to enter within the confinement space  212 . Hence, when a portion of ink is outputted through the ink outlet  214 , external air gas simultaneously enters the confinement space  212  to achieve an adequate pressure balance with the exterior environment. The ink output through the ink outlet  214  to the ink-ejecting member  300  can be thereby sustained. 
   To prevent ink leakage through the air inlet  216 , usually caused by an ink flow along an interface  230  between the ink storage body  220  and an inner sidewall of the ink tank  210 , a plurality of notches  221   b  are formed on the ink storage body  220 . More particularly, the notches  221   b  are distributed along the outer surface of the ink storage body  220  at first and second end portions  220   a ,  220   b  thereof. The first end portion  220   a  designates a portion of the ink storage body  220  that is approximately close to the air inlet  216 , and the second end portion  220   b  designates a portion of the ink storage body  220  that is approximately close to the ink outlet  214  and relatively farther from the air inlet  216 . The disposition of notches  221   b  hence creates a distribution of gaps  232  that cut off the continuity of the interface  230  to the air inlet  216 . Via adequate geometry, curvature and depth of the gaps  232 , the ink flowing path along the interface  230  is lengthened meanwhile the progression of ink flow is hampered. Reverse ink flow causing leakage through the air inlet  216  is thereby substantially reduced. An adequate geometry of the gaps  232  may be, for example, a circular recess that runs around the outer surface of the ink storage body  220  from the first portion  220   a  to the second end portion  220   b.    
   Referring to  FIG. 3 , a sectional view schematically illustrates the construction of an ink storage unit according to another embodiment of the invention. In this embodiment, an ink storage unit  202  similarly includes an ink tank  210  that defines an inner confinement space  212 . In the confinement space  212  is disposed an ink storage body  222  that is comprised of a first storage portion  222   a , a second storage portion  222   b , and a spacing member  222   c . The first storage portion  222   a  is placed close to the air inlet  216  while the second storage portion  222   b  is placed close to the ink outlet  214  and relatively farther from the air inlet  216 . The spacing member  222   c  is arranged between the first storage portion  222   a  and the second storage portion  222   b  so as to separate both portions  222   a ,  222   b  from each other. 
   As illustrated in  FIG. 3 , the spacing member  222   c  may be formed from, for example, a plurality of ribs that oppositely abut against the first and second ink storage portions  222   a ,  222   b , thereby creating a spacing gap there between. As a result, ink initially stored in the second ink storage portion  222   b  is effectively prevented from reversely flowing to the first ink storage portion  222   a  and leaking out through the air inlet  216 . It should be noticed that since the first ink storage portion  222   a  is not principally used to store an important amount of ink, materials of smaller pore density (such as smaller-pore-density sponge or fabric), more economical, can be therefore advantageously used to fabricate the first ink storage portion  222   a.    
   As shown in FIG.  2  and  FIG. 3 , a notch  221   a  in FIG.  2  and notch  221   b  in  FIG. 3  placed vis-à-vis the air inlet  216  as conventionally achieved may be further associated with the distribution of gaps of the invention to further efficiently prevent ink leakage through the air inlet  216 . 
   As described above, the invention therefore provides an ink storage unit that effectively prevents ink leakage through the air inlet due to ink flowing along the interface between the ink tank and the ink storage body received therein. For this purpose, an embodiment of the invention provides an ink storage body that is comprised of a plurality of notches formed on an outer surface thereof. The disposition of notches hence forms a distribution of gaps along the interface between the ink storage body and the ink tank that lengthens the ink flowing path to the air inlet and further hampers the progression of ink flow. Another embodiment of the invention provides an ink storage body that is comprised of first and second ink storage portions separated from each other via a spacing member placed there between, the first ink storage portion being close to the air inlet while the second ink storage portion being close to the ink outlet. The above spacing member creates a spacing gap between the first ink storage portion and the second ink storage portion that effectively prevents ink leakage to the air inlet. 
   It should be apparent to those skilled in the art that other structures that are obtained from various modifications and variations of various parts of the above-described embodiments of the invention would be possible without departing from the scope and spirit of the invention as illustrated herein. Therefore, the above description of embodiments and examples only illustrates specific ways of making and performing the invention that, consequently, should cover variations and modifications thereof, provided they fall within the inventive concepts as defined in the following claims.