An ink cartridge for a printer

Abstract: An ink cartridge (1) for a printer comprises a casing (2) containing a porous ink storage body (12). A bottom wall (3) of the cartridge casing (2) has an opening therethrough for communication with a print head. An area of the inside face of the bottom wall (3) around the opening has a plurality of grooves that open to the opening. The area is covered by a sieve against which the porous body (12) is held in contact.

Description: Background of the Invention The subject invention is directed toward the art of ink jet printers and, more particularly, to an improved ink storage cartridge for such printers. Cartridges for ink jet print heads or matrix print heads comprising a casing which contains a porous ink storage body are known from U.S. Patent Nos. 4,771,295, 5,158,377, 5,221,148, and 5,421,658. A tubular socket of the print head extends into the interior of the casing and locally compresses the porous body. It is assumed that this local compression increases the capillarity of the porous body around the socket so that the ink content of the porous body can be used more completely. EP-A-624 475 discloses in one embodiment an ink cartridge according to the preamble of claim 1. It comprises a housing with an opening through a wall. A plurality of grooves extend from the opening on the inner side of the wall. The housing contains a porous ink storing body. In a different embodiment the porous body is provided with through going holes. When cutting these holes there remain waste particles. In order to retain those in the cartridge a filter is placed on the inside of the wall. Summary of the invention The object of the present invention is to provide a different way of utilising the ink content of the porous body as completely as possible. The cartridge of the present invention comprises a housing with a bottom wall containing an opening for connection with the print head. An inside face of the bottom wall has an area around the opening provided with a plurality of grooves that open to the opening. The area is covered by a sieve that overlies the grooves. The housing further contains a porous body which is held in contact with the sieve. Preferably, the grooves extending form the open-like configuration comprise radial grooves extending from the opening and branch grooves extending from at least some of the radial grooves. The pore size of the sieve is smaller than the pore size of the porous body. With the present invention, the active area of the sieve through which the ink passes when consumed by the print head is considerably increased as compared to the cartridges of the prior art. This substantially reduces the flow resistance of the filter. Still other advantages and benefits of the invention will become apparent to those skilled in the art upon a reading and understanding of the following detailed description. Brief Description of the Drawings The invention may take physical form in certain parts and arrangements of parts, a preferred embodiment and method of which will be described in detail in this specification and illustrated in the accompanying drawings which form a part hereof, and wherein: FIGURE 1 is a cross section of a cartridge for an ink jet or a matrix print head; and, FIGURE 2 is a top view of the cartridge with the cover, porous body, and sieve removed. Detailed Description of the Preferred Embodiment Referring now to the drawings wherein the showings are for the purposes of illustrating the preferred embodiment of the invention only and not for purposes of limiting same, FIGURE 1 shows a cross section through the cartridge 1 including a casing 2 comprised of a bottom wall 3, four lateral walls 4, and a cover 5 welded or sealed onto the free edges of the lateral walls 4 . A tubular socket 6 with a cylindrical bore 7 fits onto and receives a tubular extension or socket of the print head (not shown). An opening 8 through the bottom wall 3 connects the bore 7 with the interior of the casing 2. The casing 2 contains a porous body 12 of foamed synthetic material, such as polyethylene, which is slightly compressed by 2% to 6% in a direction perpendicular to the bottom wall 3 and cover 5 over most of their area. The cover 5 has an opening 13 for admitting air to a small recess 14 in the body 12 underneath the cover 5 . An area 15 of the inside face 16 of the bottom wall 3 around the opening 8 contains a plurality of radial grooves 17 which are in fluid communication with the opening 8 by having their inner ends opening thereto. The grooves preferably increase in cross section towards the opening 8 . Branch grooves 18 extend from half of the radial grooves 17 . The area 15 with the grooves 17, 18 is covered by a sieve 19 which closely overlies the grooves and against which the foam body 12 is pressed. The sieve 19 is preferably a web of synthetic material, e.g., of nylon, or a web of metal, e.g., stainless steel. Alternatively, a fleece of synthetic material or metal may be used. The pore size of the sieve 19 is considerably smaller than the pore size of the foam body 12 and is preferably between 1 and 10 µ m. As a result, there is achieved an efficient filtering of the ink and, further, air bubbles are prevented from passing through the sieve 19. In this way, the bore 7 remains full of ink until all the ink contained in the foam body 12 is used up. Thus, a safer operation of the print head is achieved after exchange of a new cartridge for a used one.

Claims: An ink cartridge for a printer comprising: a housing (1) including a first wall (3) having an inner face (16) ; an opening (8) formed through the first wall (3) with an entry end in said inner face; an area (15) of said inner face around said entry end of said opening (8) being provided with a plurality of grooves (17) that open to said entry end of said opening (8); a porous ink storing body (12) in the housing (1) characterised by a sieve (19) mounted on said inner face (16) and overlying said grooves (17) said porous body (12) being held in contact with said sieve (19), the pore size of said sieve (19) being smaller than the pore size of the body (12). The cartridge of claim 1 wherein a plurality of said grooves extend radially to the opening. The cartridge of claim 2 including additional grooves extending as branch grooves from at least some of said radially extending grooves. The cartridge of claim 1 wherein the pore size of the sieve is greater than 1 µ m. The cartridge of claim 4 wherein the pore size of the sieve is less than 10 µ m. The cartridge of claim 1 wherein the sieve is a web of synthetic material. The cartridge of claim 1 wherein the sieve is a web of metal. The cartridge of claim 1 wherein the sieve is a fleece. The cartridge of claim 1 wherein the porous body is compressed in the direction perpendicular to the bottom wall over most of the area of the bottom wall. The cartridge of claim 1 wherein the degree of compression of the porous body is at least 2%. The cartridge of claim 10 wherein the degree of compression of the porous body is not substantially greater than 6%.

Inventors: BETSCHON LUZIUS, BETSCHON, LUZIUS
Applicants: NU KOTE INT INC, PELIKAN HARDCOPY PRODUCTION AG, NU-KOTE INTERNATIONAL, INC.
Application year: 1997
Main classification: B41J2
IPC codes: B41J2