WO2001019615A1

WO2001019615A1 - Method and apparatus for refilling an ink cartridge with a printhead mounted on it

Info

Publication number: WO2001019615A1
Application number: PCT/SG1999/000094
Authority: WO
Inventors: Seng Huat Ser
Original assignee: Fullmark Private Limited
Priority date: 1999-09-13
Filing date: 1999-09-13
Publication date: 2001-03-22
Also published as: AU6127699A

Abstract

The present invention is directed to modified ink cartridge (11) of the type which has a printhead (8) mounted thereon and an adapter (2) for receiving a replaceable ink tank (15) so that the printhead may be reused a number of times. The adapter comprises locking elements (26) for snapping into locking means (13) of the cartridge shell and additional locking means for retaining a replaceable ink tank. The adapter of the present invention includes a seal ring (3) and felt wick (4) for communicating ink from the ink tank to the printhead without leakage. The ink tank contains an ink-impregnated foam (17) which contacts the felt wick. Ink flows from the ink tank via the felt wick and to the printhead. The high capillarity of the felt wick facilitates the flow of ink without the need to compress the foam.

Description

METHOD AND APPARATUS FOR REFILLING AN INK CARTRIDGE WITH A PRINTHEAD MOUNTED ON IT

FIELD OF THE INVENTION The present invention relates to ink jet ink cartridges, and is specifically related to an ink jet cartridge which has an integral printhead and an adapter for receiving replaceable ink tanks for use in an ink jet printer

BACKGROUND OF THE INVENTION With the ever-increasing popularity of personal computers, ink jet printing has gained widespread use, particularly among home and small business users. Inkjet printers are low in cost and ofter high-resolution monochrome and color printing capability Generally, other techniques for color printing require the use of printers which are far more expensive The most common form of ink jet printing now in use is "drop-on-demand" or "DOD" printing. In DOD printing ink is ejected from a printhead positioned within the printer onto a print medium or substrate such as paper. Generally, the printhead comprises a plurality of ejection nozzles and a mechanism for forming and propelling ink droplets out of the nozzles. The two most common forms of DOD printheads use either thermal or piezoelectric propulsion mechanisms within the printhead. Generally, there is a separate propulsion mechanism, (e.g., resistive heater or piezoelectric tube), and firing chamber associated with each of the printhead nozzles. As a result of this architecture, printheads usually comprise a complex miniaturized multilayer structure having a plurality of nozzles, electrical traces and terminals for delivering power to the propulsion mechanism as needed, and liquid channels to communicate ink from an ink supply to the firing chambers.

Commercially available DOD printers generally utilize replaceable ink cartridges to hold the ink supply delivered to the printhead during the printing process. In order to prevent leakage and to supply ink to the printhead at a desired controlled rate, many ink jet cartridges holds the supply of ink in a porous material, such as foam, impregnated with the ink. The structure of such cartridges generally includes a container comprising an enclosed shell (i.e., a plurality of walls defining a chamber or reservoir) Many cartridge designs also include a printhead mounted on one of the walls. In addition, the structure generally includes an ink pipe or channel which communicates ink between the ink reservoir and the printhead. While the foregoing description sets forth many of the common elements of the design of ink supply cartridges and printheads used in ink jet printing, it is unfortunate that the specific designs of the major ink jet printer manufacturers are much different, both between manufacturers and between printer models offered by a single manufacturer There is virtually no interchangeability of the cartridges made by the different printer companies, and little interchangeability of cartridges of a single printer manufacturer

Several manufacturers sell printers which use disposable cartridges having integrated printheads, referred to herein as "integrated cartridges". After the ink supply in an integrated cartridge is fully depleted, the basic components of the cartridge are still reusable and will last for numerous refilling of ink. Discarding the entire integrated cartridge after the ink supply is depleted is both unnecessarily costly and wasteful. Specifically, it is well known that it is unnecessary to replace the printhead each time the ink supply in the cartridge is used up. Since the printhead is the most difficult, complex and expensive component of the cartridge to manufacture, using the printhead multiple times promotes efficiency and reduces waste.

Accordingly, many printer users refill integrated cartridges rather than discarding them after one use, and several "aftermarket" companies have developed products which allow customers to refill integrated cartridges. While there are several methods and tools available to consumers for refilling integrated cartridges, the existing refill products require a certain level of skill to use, and many consumers are not comfortable using them. Moreover, existing refill methods present some the risk of a messy ink spill and may not yield a properly functioning cartridge.

In order to overcome the disadvantages associated with refill methods, it is known to modify an integrated cartridge to permit it to accept replaceable ink tanks, thereby allowing the cartridge shell and printhead to be reused. Specifically, it is known to take an integrated cartridge and to modify it by ( 1) removing the top (or cap) of the cartridge leaving the remainder of the shell and printhead with its associated circuitry intact, (2) emptying the interior of the shell by removing the ink supply system (foam or bladder) within the cartridge, and (3) adapting the cartridge to accept replaceable ink tanks The present invention is an improvement over other known designs which use this technique. In particular, when adapting an integrated cartridge to accept replaceable ink tanks, it is critical that the ink tank be precisely and securely positioned within the cartridge shell, and that there be reliable means for communicating ink between the ink tank and the printhead. Accordingly, it is an object of the present invention to provide a convenient system for reusing the printheads on integrated cartridges

A further object of the present invention is to provide a convenient and reliable ink supply system for ink jet printers of the type which use integrated cartridges which eliminates the need to dispose of the printhead when the ink supply is used up.

Another object of the present invention is to provide an improved design for an ink cartridge having an integral printhead and a removable ink tank which is compatible with existing printers

Yet another object of the present invention is to provide a method for modifying an integrated cartridge to permit it to accept replaceable ink tanks

Still another object of the present invention is to provide a system for securing a replaceable ink tank within a cartridge shell having a printhead mounted thereon, such that the ink tank is securely and precisely held in position within the cartridge shell.

A further object of the present invention is to improve the communication of ink between a replaceable ink tank and a printhead in the modified integrated cartridge of the present invention.

Yet another object of the present invention is to provide an adapter, for use in a modified integrated cartridge which facilitates the use of replaceable ink tanks.

SUMMARY OF THE INVENTION These and other objects of the present invention which will be apparent to those skilled in the art, are achieved by modifying an integrated cartridge to receive replaceable ink tanks.

In its broad form, the ink cartridge of the present invention comprises a cartridge shell having a printhead mounted thereon, an adapter mounted within the cartridge shell for receiving a removable ink tank and a felt wick for communicating ink from said ink tank to said printhead. An annular seal ring which holds^' the felt wick may be mounted on the adapter. A locking structure, which may comprise raised elements formed on at least one wall of said adapter which mate with openings formed in a wall of the cartridge shell, is used to securely and precisely hold the adapter within the cartridge shell. Likewise, a locking structure, which may comprise a plurality of slots formed in at least one wall of said adapter which mate with detents formed on an exterior surface of said ink tank, is used to securely and precisely hold said ink tank within said adapter. The slots of the ink tank locking structure may be slightly narrower in width than the detents, with the slot ends being substantially the same width as the detents, such that the detents are held in position at the end of the slots. In another aspect, the present invention comprises a method of modifying an integrated cartridge for an ink jet printer, comprising an integrated cartridge having a printhead mounted thereon and an enclosed volume for holding an ink supply, removing a wall of said integrated cartridge, and removing the interior contents of said integrated cartridge, such that a cartridge shell having a plurality of walls and a printhead mounted thereon is formed, positioning an adapter within said cartridge shell, said adapter being held in place within said cartridge shell by a locking mechanism, positioning a felt wick within said cartridge shell in the vicinity of said printhead, and providing an enclosed foam-filled ink tank which is removable from and insertable into said adapter

BRIEF DESCRIPTION OF DRAWINGS A preferred embodiment of the invention shall now be explained with reference to the drawing, in which.

Fig. I shows a longitudinal section through the cartridge of the present invention. Fig. 2 shows a longitudinal section through the replaceable ink tank of the present invention. Fig. 3 shows a bottom view of the replaceable ink tank of the present invention. Fig. 4 shows a longitudinal section through the ink cartridge adapter of the present invention, prior to mounting the seal ring and the felt wick.

Fig. 5 shows a bottom view of the adapter of the present invention. Fig. 6 shows a longitudinal section through the seal ring of the present invention. Fig. 7 shows a longitudinal section through the adapter of the present invention with the seal ring and felt wick mounted thereon.

Fig.8 shows a longitudinal section through the cartridge shell, adapter, seal ring and felt wick of the present invention prior to inserting a replaceable ink tank.

Fig. 9 shows an exploded assembly drawing of the components of the present invention.

DETAILED DESCRIPTION OF THE INVENTION Generally, the present invention is directed to a ink cartridge for use in an ink jet printer comprising an integrated printhead mounted on a cartridge shell and a replaceable ink tank which may be positioned within the shell to communicate ink from the ink tank to the printhead via a felt wick. While the following description is made in reference to a preferred embodiment as depicted in the figures, those skilled in the art will appreciate that the invention is not limited to the specific embodiments which are shown and described. Fig 1 shows an embodiment of the present invention, including a cartridge shell 1, an adapter 2 nested within the cartridge shell, a seal ring 3 and a felt wick 4 mounted on adapter 2, and a replaceable ink tank 5 nested within adapter 2 Cartridge shell 1 comprises a rectangular base plate 6 from which a projection 7 protrudes Although a rectangular base plate is shown, base plate may have any suitable shape that is compatible with the design of the printer A printhead 8 is mounted on projection 7 such that when the cartridge is positioned in the printer the nozzles of the printhead are adjacent to the print medium The structure of printhead 8 is not shown and is beyond the scope of the present invention. A plurality of electrical contacts (not shown) used by the printer to cause the ejection of drops from the printhead are also present on a wall of the cartridge shell 1.

Cartridge shell 1, including the printhead 8 can be formed from a commercial integrated cartridge of the type which includes an ink supply and a printhead integrally mounted thereon. As previously noted, many commercial ink jet cartridges have integrated printheads, and the printheads have a useful life which is far greater that the accompanying ink supply. For purposes of practicing the present invention, such a cartridge can be formed by removing a wall and internal components of the cartridge, leaving cartridge shell 1 with integral printhead 8. In the embodiment depicted in the figures, cartridge shell 1 is formed from a commercial ink jet cartridge that includes the printhead of the original cartridge.

Printhead 8 contains a nozzle plate with a plurality of the narrow openings through which ink is ejected from the printhead onto a print medium such as paper. A complete description of the mechanism for ejecting ink from the printhead is beyond the scope of the present invention. Generally, there is a microscopic chamber in the printhead associated with each of the nozzles. The pressure in each of the chambers can be selectively and rapidly increased, so that a small ink drop is ejected from the corresponding nozzle. The pressure increase is, for practical purposes, nearly instantaneous. The rapid pressure increase can be caused by heat impulses from small resistors associated with each of the chambers (thermal or "bubblejet" printing), or by a mechanical pulse associated with a piezoelectric element. As ink droplets are ejected from the printhead ink is supplied to the printhead from an ink reservoir or ink supply. Generally, because of the greater expense associated with the manufacture of piezoelectric printheads, and the longer life of such printheads, integrated ink jet cartridges presently in use are of the thermal variety. However, for purposes of the present invention, the printhead propulsion mechanism is unimportant. After ink is ejected from the firing chambers in the printhead it must be replenished Linking the ink tank 5 and printhead 8 is an inner tubular connection channel 10 which communicates with the firing chambers associated with the nozzles A close-meshed sieve or filter 12 in mounted at the interior end 1 1 of channel 10, distal from printhead 8. Filter 12 is present to block any bubbles or particles which may be in the ink supply to prevent clogging of the printhead. Use of filter 12 is important even if care is taken during ink formulation to minimize the presence of particles in the ink.

A seal ring 3, which is shown in greater detail in Fig. 6, is mounted on top of filter 12. The seal ring 3 is tubular and is adapted to securely hold a felt wick 4 which projects upwardly from the interior surface of the base plate 6 of cartridge shell 1 when adapter 2 is positioned within cartridge shell 1. Seal ring 3 is held in place by an adapter 2 as shown in Fig. 7. Preferably, felt wick 4 is held in abutment against the surface of filter 12 so as to facilitate the communication of ink from wick 4 to filter 12 and into channel 10.

Felt wick 4 preferably comprises a dense mass of plastic fibers, or any other felt materials, that are formed into the solid cylindrical shape depicted in the figures. While a cylindrical shape is shown, any suitable shape may be used and will depend on the design of the particular cartridge. Felt wick

4 is substantially rigid. In one embodiment, felt wick 4 is made from polyester other felt materials.

In contrast to prior art designs, the use of a solid felt wick increases the capillarity of the ink path between the ink supply and the printhead, thereby improving the flow of ink to the printhead. Those skilled in the art will appreciate that the amount of capillarity provided by felt wick 4 can be controlled by the material used to make the wick, its affinity for the ink used in the cartridge and its final density. The fact that felt wick 4 is a porous solid enables it to provide further filtering of the ink, beyond that provided by filter 12. Increasing the total surface area available for filtering the ink decreases the possibility of clogging the printhead than if filter 12 alone is used.

Adapter 2 is an internal shell which nests within the interior of cartridge shell 1. Adapter 2 is securely held within the interior of cartridge shell 1 by locking elements 26. In the embodiment shown in the figures, locking elements 26 on adapter 2 are snapped into locking means 13 on cartridge shell 1. In the embodiment depicted, locking elements 26 mate with openings 13 formed in cartridge shell 1. Preferably, cartridge shell 1 and adapter 2 are formed of any suitable injected molded plastic, and locking elements 26 may comprise raised portions which project from the outer surfaces of the sides of adapter 2 as shown in Fig. 5. While only two locking elements 26 are shown in Fig 1 , i.e.. on one side of adapter 2. in the preferred embodiment there are locking elements 2t> on both sides of adapter 2 as shown in Fig 5 The number and position of the locking elements may be changed depending the specific requirements without departing from the present invention. When using a commercial integrated ink jet ink cartridge to form cartridge shell 1 , openings 13 may be formed by drilling, punching, or any other suitable means. The locking means of the present invention allows adapter 2 to be precisely and securely positioned within cartridge shell 1. The preferred locking means also allows adapter 2 to be removed from cartridge shell 1.

Adapter 2 of the ink cartridge of the present invention is configured to receive a replaceable ink tank 5. As is shown in Fig. 1 , the ends of cartridge shell 1 and adapter 2 which are opposite from printhead 8 are completely open thereby permitting the insertion of replaceable ink tank 5 of the present invention and allowing ink tank 5 to nest within the interior volume defined by the walls of adapter 2 It is noted that in the embodiment shown in the figures, replaceable ink tank 5 has a portion, distal from printhead 8, which projects beyond the volume defined by adapter 2. This projecting portion allows ink tank 5 to hold a greater volume of ink. The size and shape of any projecting portion of ink tank 5 is limited by the interior dimensions and configuration of the printer in which the cartridge is to be used.

Seal ring 3 retains felt wick 4 in place and maintains a leakproof seal between replaceable ink tank 5 and adapter 2 when ink tank 5 is inserted into cartridge shell 1. Seal ring 3 may be formed of any suitable elastomeric material. As shown in Fig. 4, bottom wall 23 of adapter 2 has an aperture

24 for holding seal ring 3. Seal ring 3 has an annular groove 9 having a diameter which is substantially the same as the diameter of aperture 24, such that seal ring 3 can be easily mounted on and securely held by adapter 2 as shown in Fig. 8. When adapter 2 is mounted within cartridge shell

1, seal ring 3 also prevents leakage of ink at the interface between close-meshed sieve 12 and felt wick 4. Preferably, the structure shown in Fig. 8 is made by first fitting seal ring 3 into aperture 24 and then inserting the felt wick 4 into seal ring 3. Felt wick 4 may be pressure fit or may be held securely within seal ring 3 by gluing or other suitable means of attachment. Adapter 2 is then inserted into cartridge shell 1 and the locking elements 26 of are adapter 2 snapped into openings 13.

Adapter 2 has four slots 15 (only two of which are shown in Fig. 1) which receive mating raised detents 14 on ink tank 5 to securely and precisely hold ink tank 5 in its proper position within adapter 2. Again, while four slots are shown, the number and position of the slots may be changed without departing from the present invention Preferably, as shown in Fig. 4, slots 15 are slightly narrower than the diameter of circular detents 14 along most of their length with the ends of each slot 15 having substantially the same diameter as detents 14 This configuration allows detents 14 to be securely retained at the ends of the slots 15 It will be appreciated by those skilled in the art that the plastic materials used in ink cartridges have sufficient elasticity to allow detents 14 to pass along slots 1 when moderate pressure is applied

Turning to Fig 2, replaceable ink tank 5 consists of a plastic housing 16 for holding a block of foam 17 Housing 16 is preferably made from two pieces, a main body 30 and a plastic cover 18 Again, the pieces used for housing 16 are, preferably, injection molded plastic. An air vent 19 is formed in housing 16, preferably in cover 18, to allow air into the ink tank to replace ink that is consumed The bottom wall 20 of housing 16 has an opening 21 for receiving felt wick 4 when ink tank 5 is inserted into adapter 2. Preferably, housing 16 is completely filled with foam 17. After foam 17 is placed in main body portion 30, cover 18 is affixed to the main body. Cover 18 may be affixed by gluing, melting or other suitable means.

Any suitable type of foam material may be used in connection with the ink tank 5 of the present invention. As is known in the art, when using certain types of foam, it may be desirable to form the foam block larger than the volume of housing 16 so that it is compressed upon insertion into the ink tank. As is also known in the art, it is desirable to control the porosity of certain types of foam so that the foam provides a desired backpressure. Compression of the foam may be used to control its porosity.

After ink tank 5 is constructed the foam 17 in housing 16 is impregnated with suitable ink. Ink may be injected into the ink tank through air vent 19 or through opening 21. Thereafter, it is desirable to seal air vent 19 and opening 21 until the ink tank is ready for use. A suitable tape or foil, or any other suitable sealing means, may be used to seal the openings. Of course, any seals placed over opening 21 or air vent 19 must be removed prior to using ink tank 5.

When the ink tank 5 is inserted into the adapter 2, felt wick 4 contacts foam 17. Because of the high capillarity of felt wick 4, ink is immediately drawn out of the foam and is transmitted to filter 1 1 and into channel 10 The high capillarity of felt wick 4 avoids the need to rely upon compression of the foam to draw ink to the outlet of the ink tank, as in prior art designs. Upon contact, the ink will naturally flow to the higher capillarity felt wick without the need for compression of the foam. This permits reliable operation of the cartridge of the present invention directly upon insertion of replaceable ink tank 5 The contact between foam 17 and felt wick 4 and between felt wick 4 and close-meshed sieve 12 are ensured by positive engagement of the locking means and elements

The present invention also comprises a method of modifying a commercially available integrated ink tank to adapt it to receive replaceable ink tanks. The method of the present invention comprises the steps of obtaining an integrated cartridge, removing a wall of the cartridge, and removing the ink supply system within the cartridge, thereby leaving a cartridge shell 1 having a printhead 8 mounted thereon. Locking means 13 for engaging an adapter 2 are then formed on cartridge shell 1 As previously noted, locking means 13 may be formed by drilling, cutting or punching one or more walls of the cartridge shell.

In forming cartridge shell 1 in accordance with the present invention, it may also be necessary to modify the interior configuration of the cartridge shell 1 to facilitate the insertion of an adapter 2 and an ink tank 5. For example, it may be necessary to remove structures which are present on the interior walls of the cartridge shell which project into the interior volume of the cartridge shell.

After cartridge shell 1 is suitably modified, adapter 2 comprising a seal ring 3 and a felt wick 4 is inserted into cartridge shell 1. Adapter 2 has locking elements 26 which mate with the locking means 13 on cartridge shell 1, thereby holding adapter 2 securely and precisely in position, and providing a seal between felt wick 4 and filter 12 mounted on the cartridge shell 1. Thereafter, replaceable ink tanks 5 may be inserted into adapter 2 to allow printhead 8 and cartridge shell 1 to be used with a number of ink supplies. Inserting ink tank 5 into adapter brings felt wick 4 into contact with ink saturated foam within the ink tank. Sealing means 3 also provides a seal between ink tank 5 and adapter 2.

While the present invention has been described in connection with a preferred embodiment, those skilled in the art will appreciate that modifications can be made to the specific design that has been described and shown in the drawings without departing from the scope of the present invention.

Claims

CLAI S

What is claimed is

1 An ink supply system for an ink jet printer, comprising a cartridge shell having a printhead mounted thereon, an adapter mounted within said cartridge shell for receiving a replaceable ink tank containing a supply of ink, a felt wick mounted within said cartridge shell for communicating ink from ink tank to said printhead.

2 The ink supply system of claim 1 further comprising a seal ring mounted on said adapter, and wherein said felt wick is held in position by said seal ring.

3 The ink supply system of claim I further comprising means for locking said adapter securely and precisely in position within said cartridge shell.

4. The ink supply system of claim 1 wherein said means for locking said adapter within said cartridge shell comprises a locking elements formed on said adapter which mate with locking means formed on said cartridge shell.

5. The ink supply system of claim 4 wherein sad locking elements formed on said adapted comprise raised portions and said locking means formed on said cartridge shell comprise openings for receiving said raised portions.

6. The ink supply system of claim 1 further comprising ink tank locking means for securely and precisely holding said replaceable ink tank within said adapter.

7. The ink supply system of claim 6 wherein said ink tank locking means comprises a plurality of slots formed in said adapter for receiving detents on said replaceable ink tank.

8 The ink supply system of claim 7 wherein said slots have a width which is slightly narrower than said detents along most of their length, the end of each slot having a width which is substantially the same as the diameter of said detents, such that the ink tank will be precisely and securely held in position within said adapter.

9 An ink supply system for an ink jet printer comprising: a cartridge shell, removably mountable within an ink jet printer, said cartridge shell having a printhead and a filter mounted on a bottom portion thereof, said cartridge shell further comprising a plurality of side wall, at least one of said sidewalls having openings, an adapter mounted within said cartridge shell, said adapter having raised portions which mate with said openings such that said adapter is securely held within said cartridge shell, an annular seal ring mounted on said adapter, said seal ring having a felt wick mounted therein, such that when said adapter is positioned within said cartridge shell, said felt wick abuts said filter, a removable enclosed ink tank comprising ink-saturated foam within the interior volume thereof, wherein said adapter has a plurality of slots for receiving detents on said ink tank, such that said ink tank is securely and precisely held in position within said adapter, and wherein said felt wick contacts said foam when said ink tank is positioned within said adapter.

10. A method of modifying an integrated cartridge used in an ink jet printer, comprising: obtaining an integrated cartridge of the type which is designed for use within said ink jet printer, said integrated cartridge having a printhead mounted thereon and an enclosed volume for holding an ink supply, removing a wall of said integrated cartridge, and removing the interior contents of said integrated cartridge, such that a cartridge shell having a plurality of walls and printhead mounted thereon is formed, positioning an adapter within said cartridge shell, said adapter being held in place within said cartridge shell by a locking mechanism comprising raised members formed on said adapter which mate with openings formed in at least one wall of said cartridge shell walls, said adapter having a plurality of slots formed in at least one wall thereof and an opening in a bottom wall thereof, positioning a felt wick within said cartridge shell in the vicinity of said printhead, providing an enclosed foam-filled ink tank which is removably insertable into said adapter, said ink tank having a plurality of detents which mate with said slots of said adapter such that said ink tank is securely held in position within said adapter and said felt wick contacts said foam when said ink tank is inserted into said adapter.