WO1998006584A1

WO1998006584A1 - Service station for ink jet printers

Info

Publication number: WO1998006584A1
Application number: PCT/US1997/000431
Authority: WO
Inventors: Charles C. Lee; Bruce H. Koehler
Original assignee: Minnesota Mining And Manufacturing Company
Priority date: 1996-08-15
Filing date: 1997-01-14
Publication date: 1998-02-19
Also published as: AU1533497A

Abstract

The invention concerns an ink jet service station having a removable foam member within an elastomeric ink jet head seal for capping an ink jet nozzle wherein the seal forms an air-sealed cavity for the nozzle and the foam member contacts the nozzle. The invention also concerns an ink jet service station having a multiplicity of recessed pad seats, a removable foam member for contacting an ink jet nozzle, and a spittoon reservoir for each pad seat connected to that pad seat by a channel.

Description

Service Station for Ink Jet Printers

Field of Invention

This invention relates to service stations in ink jet printers that minimize complications during capping, i.e., storage or other non-use of the ink jet cartridge.

Background of Invention

The mechanics of an ink jet cartridge, rapidly becoming a necessity in commercial and consumer desktop publishing, are very complicated. Very fine droplets of ink, on the order of 60 μ in diameter, are propelled from the cartridge to the receiving substrate through a very small nozzle(s), on the order of 30-60 μm in diameter (with the ink droplet emerging from the nozzle with a cylindrical shape). When the ink jet cartridge is working well, images having as much as 800 dots per inch (dpi and also known as pixels) can produce photographic-quality images. With the ability to convert any digital image stored electronically to an image on a substrate, the technology of printing and publishing has been changed forever.

When the ink jet cartridge is not working well, images are distorted if produced at all. A common problem with ink jet cartridges is the natural tendency of solvents and other carrier liquids propelling the ink to evaporate at critical locations in the ink jet cartridge. Evaporation of the liquid on the substrate is required; evaporation on the cartridge head leaves ink-based residues clogging the ink jet cartridge nozzle(s). A distorted image, or no image, results, with material waste and the attendant frustration for the user of the ink jet printer. Most ink jet printers have attempted to solve the problem of premature evaporation of the ink at the cartridge head by providing a controlled environment for the head at the end of printer usage. The controlled environment is called a service station in the ink jet printer. Service stations in ink Jet printers serve important maintenance functions, such as "Wiping" (which cleans the surface of the cartridge head), "Spitting" (which fires the nozzles before printing to clear them of any ink residue), and "Capping" (which seals the nozzles in the ink jet print head usually with a rubber "head seal capper" when not printing or when the printer is off)

Currently commercially available ink jet printers available from Encad, Inc of San Diego, California USA (e g , NovaJet II, Novajet III, and Novajet Pro ink jet printers) use a conventional rubber head seal capper in the form of a rectangular cup When the print head is seated at the service station in contact with the capper, the area surrounding the nozzles is sealed from the outside environment

However, the nozzles themselves are still exposed to the air inside the sealed capper. Solvents or other carrier liquids in the ink at the nozzle(s) inside the sealed capper can evaporate As a result, the printer could fail to produce an acceptable image

One attempt has been undertaken to address this problem Sign- Tronic USA, Inc. (Racine, Wisconsin, USA) provides a modification kit for a service station that replaces the conventional rubber head seal capper with a post having a permanent pad for contacting the print head But such modification is permanent and does not permit facile replacement of pigment-based inkjet cartridges with dye-based inkjet cartridges

U S Pat No 5, 146,243 (English et al ) discloses a bidirectionally movable carriage with a diaphragm cap system which diaphragm flexes to minimize pressure differentials between the interior and exterior of the cap

U.S Pat No 4,872,026 (Harmon et al ) discloses a service station for clearing clogged nozzles with reference pads being provided for aligning and securing the printing cartridge in a carriage U.S Pat No. 5,434,605 (Osborne) discloses a priming of a selection of a number of printheads by vacuuming the selected tube to an adjustable pressure differential

U.S. Pat No 5,448,270 (Osborne) discloses an inkjet print head cap with a peripheral channel and is made of flexible material and is resiliently deflectable by a force impacting above the channel European Patent Publication 0 589 582 A2 discloses a wiping system which in a service mode places a predefined uncapping and wiping positions relative to corresponding printheads.

European Patent Publication 0 635 371 A2 discloses an ink-jet printer priming cap and system whereby a diaphragm in the cap is used to induce a vacuum for initiation of ink flow.

Summary of Invention

Conventional rectangular cup service stations work acceptably for cartridges holding black and color dye-based inks, but not very reliably for cartridges holding pigment-based inks.

Pigment-based inks have a tendency to dry out at the nozzles when the nozzles are uncapped without firing, or when the nozzles are capped in the standard service station for longer than 20 minutes. As a result, printing will fail after either of these two events.

The present invention provides a service station that functions well for both dye-based inks and pigment-based inks with easy substitution of one type of ink with the other type of ink.

One aspect of the present invention is an inkjet service station that comprises a removable foam member within an elastomeric ink jet head seal for capping a ink jet nozzle wherein the seal forms an air-sealed cavity for the nozzle and the foam member contacts the nozzle.

Another aspect of the present invention is an ink jet service station, that comprises a multiplicity of recessed pad seats, a removable foam member for contacting an ink jet nozzle, and a spittoon reservoir for each pad seat connected to that pad seat by a channel.

A feature of the present invention is the ability of a capper insert or service station to work with both dye-based ink jet cartridges and pigment-based inkjet cartridges with facile transition between the types of ink jet cartridges to minimize evaporation of solvent or carrier liquid at the cartridge head. An advantage of the present invention is the ability to use a service station of the present invention to protect pigment-based inkjet cartridges from evaporation of solvent or carrier liquid for several days, an improvement over conventional service station by a factor of two-hundred fold. Further features and advantages are identified with reference to the embodiments of the invention described according to the following drawings.

Brief Description of Drawings

Fig. 1 is a perspective view of a capper insert of the present invention for conventional service stations.

Fig. 2. is a perspective view of a second embodiment of a capper insert.

Fig. 3 is a perspective view of an improved service station for inkjet printers.

Fig. 4 is a perspective view of one embodiment of a capper insert for the improved service station of Fig. 3.

Fig. 5 is a perspective view of a second capper insert for the improved service station of Fig. 4. Fig. 6 is a perspective view of another embodiment of a capper insert.

Embodiments of Invention

Fig. 1 is a perspective view of a capper insert 10 designed to removably fit within a conventional service station of an ink jet printer. The insert 10 can comprise one portion or two portions.

The first portion is a cavity-filling lower member 12 having a shape corresponding to the interior cavity of a ink jet rubber head seal on the conventional service station. The second portion is head-contacting upper member 14 adhered to the lower member 12 having length and width dimensions corresponding an upper surface 16 of lower member 12 and a height, which in combination with lower member 12, permits insert 10 to contact an inkjet head without damaging the head

In order to removably fit into an existing rubber head seal, such as on a service station of an inkjet printer (Nov,aJet II or NovaJet III branded printers commercially available from Encad, Inc of San Diego, California, USA), lower member 12 has a bottom surface 18 of smaller dimension than the upper surface 16, which is obtained by beveling or otherwise contouring the lower member 12, as seen in Fig 1 Beveling is preferred to accommodate residual adhesive when a bottom vent plate associated with the rubber head seal is affixed to the service station

Acceptable dimensions for removable insert 10 are a length ranging from about 5 0 to about 5 4 mm and preferably about 5 2 mm, a width ranging from about 1 85 to about 2 15 mm and preferably about 2 0 mm; and a total height ranging from about 9 to about 10 mm and preferably about 9 1 mm Lower and upper members 12 and 14 have approximately the same length and width, but have different heights Upper member 14 for contacting an ink jet head has a height ranging from about 1 5 to about 1 7 mm and preferably about 1 6 mm Lower member 12 for inserting into the rubber head seal of the service station has a height ranging from about 7 3 to about 8 3 and preferably about 7 5 mm

Lower member 12 can be made of any sturdy material, ranging from metals to polymers Lightweight, easily moldable, inexpensive materials are preferred such as aluminum, stainless steel, copper, brass, polycarbonate, or other thermosetting plastics In the event that inexact tolerances causes differences in height of the rubber head seals above the service station, optionally, the lower member bottom surface 18 can have an adjustable set screw seated therein for altering the height of the insert 10 as required

Upper member 14 can be made of a foamed material, ranging from natural foams to synthetic foams. Such foams should be closed-cell foams and can be selected from such materials as vinyl, neoprene, or urethane, or other medium or high density closed cell foams that are compatible with the ink chemistry which such foams contact during use. Preferably, the foam is adhesive-backed for attachment to upper surface 16 of lower member 12. Nonlimiting examples of foams useful in the present invention include closed cell foams commercially available as "12RS" outlet and switch sealer foams from W.J. Dennis & Company of Elgin, Illinois, USA, and ScotchFoam™ brand No. 4516 single coated vinyl foam having a thickness of about 1.6 mm (1/16 inches) commercially available from 3M, St. Paul, Minnesota, USA.

If one material satisfies all of the properties required for both upper and lower member 14 and 12, then that single material can be used, permitting the insert 10 to comprise only one portion.

Fig. 2 shows a second embodiment of a removable capper insert 20 of the present invention. This embodiment comprises three or more portions.

Lower member 22 corresponds to lower member 12, except that top surface 26 and lower surface 28 have the same length, and that lower member 22 has a height ranging from about 5.0 to about 5.4 mm and preferably about 5.2 mm.

Upper member 24 comprises two parts: a first foam member 25 corresponding to upper member 14 and a second foam member 27 that has greater length and width in order to provide more tolerance on the capping zone for nozzles. Lower member 22 can be made from the same materials as lower member 12. First foam member 25 can be made from the same materials as upper member 14. Second member 27 can be made from thin foam, or a piece of Precise Mousing Surface Foam commercially available from 3M.

Acceptable dimensions for insert 20 are a length ranging from about 5.0 mm to about 5.4 mm and preferably about 5.2 mm; a width ranging from about 1.85 to about 2.15 mm and preferably about 2.0 mm; and a total height ranging from about 9 to about 10 mm and preferably about 9.1 mm.

Lower member 22 and first foam member 25 have approximately the same length and width, but have different heights. First foam member 25 has a height ranging from about 1.5 to about 1.7 mm and preferably about 1.6 mm. Lower member 22 has a height ranging from about 6.8 to about 7.5 mm and preferably about 7.0 mm.

Second foam member 27 for contacting the nozzles (even if nozzles do not accurately align with rubber head seal) has a greater length and width than first foam member 25, ranging from about 5.5 mm to about 6.5 mm and preferably 6.2 mm in length and from about 2.2 to about 3.0 mm and preferably 2.8 mm in width. Second foam member 27 has a height ranging from about 0.5 to about 0.7 mm and preferably 0.6 mm.

Fig. 3 is a perspective view of an improved service station capable of accepting two different removable foam pads shown in Figs. 4 and 5.

Service station 30 allows the use of a removable solid foam pad 40 for pigment-based inks (see Fig. 4), or an open foam pad 50 for dye-based inks (see Fig. 5). Pads 40 and 50 can be easily interchanged for users who wish to switch between ink types in a single service station 30. Service station 30 has recessed pad seats 32 (a-d for each of four colors) and spittoon reservoirs 34 (a-d for each of the four colors typically used in inkjet printing). Pads 40 or 50 can be fit into the pad seats.

Small channels 36 (a-d) between each pad seat 32 and its associated spittoon reservoir 34 allows air to pass through the center of the foam pad 40 or 50 and out through the channel 36 under the pad 32 and into the adjoining spittoon reservoir 34.

In the event that ink leaks out of a dye-based cartridge, it will pass through the center hole 52 of the pad 50, through the channel 36, and into the spittoon reservoir 34. Channels 36 allow air within the center hole of the pad to escape as it is compressed against the print head. Without this channel 36, the air inside the pad 50 could be compressed, and could force air into the nozzles of the cartridge print head. The cartridge head could then fail to eject ink.

Pad seats 32a-32d can have dimensions matching the size of pads 40 and 50, namely ranging from about 12.2 mm to about 12.9 mm in length, from about 5.84 mm to about 6.5 mm in width, and from about 3.05 mm to about 3.3 mm in height. Preferably, the length is about 12.7 mm the width is about 6.35 mm, and the height is about 3.17 mm.

Service station 30 has several advantages over conventional service stations by providing the ability to use the different pad styles, a spittoon reservoir for each ink color, and a thicker, stiffer construction to prevent sag of the center two cappers.

Service station 30 can be made of any stiff material such as glass- filled nylon, glass-filled polyester, or aluminum.

Foam pad 40 can be made using the same materials as upper member 12 or first foam member 25.

Foam pad 50 can be made from medium density closed cell vinyl foam (such as 3M Scotchfoam™ 4718 from 3M), high density closed cell vinyl foam (such as Scotchfoam™ 4508 from 3M), or other medium to high density closed cell foams that are compatible with the ink chemistry which they contact during use.

Foam pad 50 has a rectangular hole 52 in the center about 2.5 mm x 6.35 mm (0.10 x 0.25 inches) in size. This hole prevents the pad from directly contacting the print head nozzles.

The bottom surface of the pads 40 and 50 can have an adhesive layer to allow them to be fastened into the pad seats 32 of the service station 30.

Besides being used with station 30 shown in Fig. 3, pads 40 or 50 can be used with conventional service stations associated with Encad brand NovaJet Pro, Pro-50 and NovaJet IV printers, provided the dimensions are adjusted to be about 8 mm in length, 8 mm in length, and 3 mm in height. Fig. 6 shows a third embodiment of a removable capper insert 60 of the present invention, having a combination of features found in inserts 10 and 20. This embodiment comprises two or more portions.

Lower member 62 corresponds to lower member 12, except that lower member 62 has a height ranging from about 4.8 to about 5.4 mm and preferably about 5.0 mm. Upper member 64 comprises a foam member 67 that corresponding to second foam member 27.

Lower member 62 can be made from the same materials as lower member 12 or can be made from twin pieces of thin adhesive backed foams (with mating of the two adhesive surfaces) available from 3M as 3M Precise Mousing Surface foam or 3M Active Strips foam products. Foam member 67 can be made from thin foam, or a piece of Precise Mousing Surface Foam commercially available from 3M or can be made from vinyl door bottom sweep material for aluminum storm doors in either a T-profile or a V-profile fashion, such as the product 37T or 37V from the Dennis Co. of Elgin, Illinois. Use of the vinyl door material provides an angle on the top surface of member 67, whereas use of Precise Mousing Surface foam provides an essentially flat surface on the top of member 67.

Acceptable dimensions for member 62 are a length ranging from about 5.0 mm to about 6.4 mm and preferably about 5.8 mm; a width ranging from about 1.85 to about 2.15 mm and preferably about 2.0 mm; and a total height ranging from about 4 to about 6 mm and preferably about 4.8 mm. Foam member 67 for contacting the nozzles (even if nozzles do not accurately align with rubber head seal) has a greater length and width than lower member 62, ranging from about 6 mm to about 8 mm and preferably 7 mm in length and from about 4 to about 6 mm and preferably 5 mm in width. Foam member 67 has a height ranging from about 0.7 to about 0.9 mm and preferably 0.8 mm.

Usefulness of the Invention

Capper inserts 10 or 20 and foam pads 40 or 50 are insertable by hand and removable by tweezers or other common tool. Thus, one can switch from dye-based inkjet cartridges to pigment-based inkjet cartridges, and vice versa, with minimal disruption to the inkjet printer or the service station within.

Before printing begins, the ink nozzles of the printer are fired to clear them in what is called a "spit" cycle. As seen in Fig. 3, the ink normally lands in spittoon reservoirs 34 on the service station 30. The NovaJet II and III branded service stations do not have a spittoon reservoir 34 for yellow ink. As a result, the yellow ink gets deposited into the lower half of the service station assembly. The ink eventually builds up and can drip inside the machine, close to the servo motor and the paper drive stepper motor. The reservoirs 34 can be easily cleaned with cotton swabs or paper towels. To clean the reservoir for yellow ink in NovaJet II and III branded service stations, the user presently has to remove the entire service station assembly to gain access to the lower half. With the present invention, yellow spittoon reservoir 34a can be easily cleaned. The invention is not limited to the above embodiments. The claims follow.

Claims

What is claimed is:

1. An ink jet service station, comprising: a removable foam member within an elastomeric ink jet head seal for capping an ink jet nozzle wherein the seal forms an air-sealed cavity for the nozzle .and the foam member contacts the nozzle.

2. The service station of Claim 1, wherein the removable foam member comprises an insert comprising a cavity-filling lower member and a head- contacting upper member.

3. The service station of Claim 2, wherein the lower member has a bottom surface of smaller dimension than an upper surface of the upper member.

4. The service station of Claim 2, wherein the upper member compises a first foam member and a second foam member, wherein the second foam member has a greater length and width than the first foam member.

5. The service station of Claim 2, wherein the cavity-filling lower member is adjustable in length.

6. An ink jet service station, comprising: a multiplicity of recessed pad seats, a removable foam member for contacting an inkjet nozzle, and a spittoon reservoir for each pad seat connected to that pad seat by a channel.

7. The service station of Claim 6, wherein each removable foam member has rectangular hole of a size to prevent the foam member from directly contacting a print head nozzle.

8. The service station of Claim 6, wherein each removable foam member is a solid rectangle for contacting a print head nozzle.

9. The service station of Claim 8, wherein the multiplicity is four.