DE29521114U1 - Refill cartridge - Google Patents

Description

Dipl.-lng. KLAUS WESTPHAL * I '... 1 iv&aWstrasse.gS J··. Telephone (0 7721) 56007

Dr. rer.nat. BERND MUSSGNUG .* '. ' i &iacgr;[5-78948 VS _# -yiLfcl^j3EN Telex 7921573 wemud

Dr.-lng. PETER NEUNERT ** "*' Fax (0 7721) 5 5164

Dipl.-lng. ROBERT GOHRING

Dr. rer. nat. OTTO BUCHNER Mozartstrasse 8 Telephone {089) 54403089

Patent Attorneys D-80336 MUNICH Fax (089) 54403080

European Patent Attorneys

pmsO38g

PMS GmbH Production + recycling of

Office machine accessories Schönbronner Strasse 64 78664 Eschbronn-Locherhof

Refill cartridge

The invention relates to a refill cartridge for a print head of an inkjet printer, in particular one having a single ink chamber or several separate ink chambers, according to the preamble of claim 1.

Such refill cartridges are used in connection with so-called filling stations, as are known, for example, from DE 43 27 178 Cl. These devices consist of a holder with a sealing element, into which the print head to be filled is inserted and locked. This causes the nozzle plate on the underside of the print head and any ventilation opening to be present to be brought into sealing contact with the sealing element. A cannula holder equipped with a cannula is then placed on the inserted print head or the holder, so that the

Postbank: Karlsruhe 769 79-754 Bank account: Deutsche Bank AG Villingen (bank code 694 700 39) 146332 V.A.T No. DE142989261

Cannula is inserted into the ink chamber of the storage area. The refill cartridge is now placed on the cannula and guided through a corresponding recess in the cannula holder. During the insertion process, the cannula pierces a plug attached to the refill cartridge and thus creates a communicating connection between the ink supply in the refill cartridge and the ink chamber of the print head.

This makes it possible to refill print heads without any problems for a number of applications. Depending on the design of the print head or the ink chamber, however, there is a risk that ink will leak out if the maximum fill level is exceeded. Such situations arise when the print head is not completely empty, so there is still ink in the ink chamber and the capacity is therefore less than the contents of the refill cartridge.

In the case of a single-colour print head, this problem can be managed as long as care is taken to ensure that the print head is completely emptied before refilling. The problem is much more difficult with a multi-colour print head that is to be refilled using a comparable device. In this case, the well-known effect occurs that the individual consumption of the individual colour components varies, so that usually only one of the colour components is exhausted, whereas the supply of the other colour components is not yet exhausted. For colour-correct reproduction, it is therefore necessary to refill ink at this stage. For practical reasons, this does not only replenish the colour component whose supply has been exhausted.

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is used up, but the ink chambers of the other color components are also refilled at this time.

Replenishing the color components of which there are still significant residues in the ink chambers is critical because the volume of the corresponding refill cartridges is too large. The filling process, which is actually automatic, must therefore be constantly monitored and individually stopped early. Otherwise there is a risk that excess ink will penetrate into a neighboring ink chamber of a different color component and thus render the print head unusable.

To avoid this problem, it was already proposed in the previously registered but subsequently published DE 44 34 186 . . to provide a membrane for each of the ink reservoir chambers that acts as a ventilation valve, through which the air escaping during the filling process can be discharged, but which is otherwise impermeable to the ink. If, as required, the ink reservoir chamber is otherwise sealed, the flow of ink is stopped when all of the air in the ink chamber has been displaced and the ink is present at the membrane.

This device enables the filling process to run unattended, and automatically stops when the maximum filling level is reached. In this context, however, it is important that the ink chambers are individually and reliably sealed. Due to the design, this does not cause any problems with a number of print heads in circulation, since, with the exception of the filling and/or ventilation openings, the

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individual ink chambers are self-contained.

However, there are also print heads in circulation where the ink chambers are not sealed or cannot be sealed, so that an automatic filling process cannot be carried out even with the aid of the device described above. These are print heads where (in the case of the multi-color configuration) the individual ink chambers are separated from each other by walls, but these are not sealed at the top, for example. The ink is absorbed by a porous or sponge-like body and held in it. This prevents the ink supply from leaking out and/or getting into an adjacent ink chamber.

The invention was therefore based on the problem of further developing a refill cartridge of the type mentioned at the beginning in such a way that the disadvantages described no longer occur. In particular, it should be able to automatically stop the flow of ink as long as a certain, predetermined fill level is reached in the relevant ink chamber.

This problem is solved with a refill cartridge which has the features of claim 1. Advantageous further developments of the invention are specified by the features described in the subclaims.

The invention is based on the idea of providing the refill cartridge with a ventilation cannula that only allows the ink to flow out until the maximum fill level is reached. In concrete terms, this is achieved by the ventilation cannula ventilating the refill cartridge or the container inside

ren and opens above the ink level. The ventilation cannula penetrates the wall of the refill cartridge at the bottom and is sealed and leads into the interior of the ink chamber, with the lower end setting the maximum fill level of the incoming ink. This means that ink can initially flow out of the refill cartridge through the filling cannula, which pierced the stopper when the refill cartridge was put in place, because air is sucked into the interior of the refill cartridge through the ventilation cannula. As the filling process progresses, the ink level in the ink chamber gradually increases until it reaches the lower end of the ventilation cannula that opens into the ink supply chamber from above. After that, no more ink can flow out of the refill cartridge because the air required for this can no longer flow in. The filling process then stops automatically without the need for manual intervention.

In this context, it goes without saying that during the filling process, the interior of the refill cartridge must not have any air-carrying connection to the environment other than through the ventilation cannula itself, so that air cannot flow in once the ink level in the ink chamber has reached the ventilation cannula. It is also important that the position of the lower end of the ventilation cannula corresponds exactly to the intended fill level in the ink chamber. In this context, it is necessary to have ventilation cannulas of the appropriate size or refill cartridges equipped with them available for different print head types. Alternatively, it is also possible to use appropriate devices, such as cannula holders with different

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Differently dimensioned recesses to specify the required penetration depth of the ventilation cannula.

A refill cartridge designed in this way can be manufactured extremely cost-effectively, as only a simple ventilation cannula is required to automatically stop the filling process as soon as the ink supply is replenished. This means that the otherwise necessary membrane can be dispensed with, and depending on the configuration, the relatively complex sealing of the individual ink chambers is no longer necessary. Finally, print heads can also be refilled whose ink chambers have leaks, particularly in the transition area between the upper edge of the housing and the cover, and are therefore no longer usable for a membrane-controlled filling process.

Preferably, the ventilation cannula is guided along the inside of the wall of the usually cylindrical or prismatic container and secured there. This allows the ventilation cannula to be fixed easily and securely, in particular in the axial direction, which is particularly important for maintaining the penetration depth into the ink chamber. In the simplest case, the ventilation cannula can be integrated as an insert during the molding process of the container with the additional advantage that no further measures are necessary to seal the container separately at the point where the ventilation cannula penetrates.

One variant provides for the ventilation cannula to be subsequently inserted into the container. This can be used to provide a refill option that can be used for a variety of different print head types.

where the user selects the cannula required for the specific print head and inserts it immediately before the filling process.

Depending on the material selected, the container can be designed to be self-sealing, so that the ventilation cannula can simply be inserted (also from below) into the interior of the refill cartridge without the risk of ink accidentally leaking out. An alternative and more cost-effective option is to simply provide another plug that has this self-sealing property and is also attached as an additional plug next to the central plug for the filling cannula.

The ventilation cannula is particularly easy to use if it is inserted later if an axial stop is provided. This limits the depth at which the ventilation cannula can be inserted into the interior of the refill cartridge and ensures that the lower end, which sets the maximum filling level during the filling process, is positioned precisely.

The design of the subsequently insertable ventilation cannula opens up the possibility of a further, particularly preferred variant in which the ventilation cannula is an integral component of a filling station, as described in the document cited at the beginning (DE 43 27 178 C2). The cannula carrier that holds the filling cannulas can thus be equipped with further cannulas, namely the ventilation cannulas, which also open into the receiving recess for the refill cartridges.

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It is particularly advantageous if the filling cannula and the ventilation cannula are arranged directly next to each other, so that the refill cartridge only needs to have a single plug that can be penetrated by both cannulas. This also makes it possible to create a refill cartridge with a very small footprint, which is an advantage with smaller print heads.

Depending on the configuration of the print head, it may also be intended that the cannula holder holding the filling cannulas be designed as a cover for the print head to be filled, which can be placed directly on the housing or the outer container.

If the ventilation cannula is attached to the refill cartridge before it is plugged in, or is firmly connected to it, it must be ensured that the print head or the cannula holder that holds the filling cannulas has a corresponding opening through which the ventilation cannula can be passed. This can also be the opening through which the ink chamber is ventilated. In order to further simplify the installation of the ink cartridge, it is advantageous to provide positioning means that enable correct assignment in terms of the angular position between the refill cartridge and the print head. These can, for example, be specially shaped recesses that correspond to correspondingly shaped contour sections of the refill cartridge. It is particularly advantageous if these positioning means also serve as color coding, so that the refill cartridges can only be plugged in if they are assigned the correct color to the relevant ink chamber and, at the same time, only in the correct relative angular position.

The invention is explained in more detail below using the embodiment shown schematically in the figures. They show:

Figure 1 Refill cartridge in schematic sectional view and

Figure 2 Refill cartridge, placed on a print head, in a schematic sectional view.

A refill cartridge 1 consists of a container 10 which is closed with a cap 12. The cap 12 sits airtight on the container 10.

Opposite the cap 12, a stopper 14 is provided on the container 10, which is intended to be pierced by a filling cannula 110 in the manner described below.

Furthermore, the refill cartridge 1 is provided with a ventilation cannula 20, which largely penetrates the container 10 axially on the inside and ends near the lid 12. On the outside, the ventilation cannula 20 penetrates the container 10 in a sealed manner and ends below. Thus, a first axial section 20i runs inside and a second axial section 20a runs outside the container 10.

The container 10 is filled with ink T, whereby in the upright position of the refill cartridge 1 shown in Figure 1, the level of the stored ink T ends below the upper end of the ventilation cannula 20.

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In Figure 2, the refill cartridge 1 is placed on a print head 200. This has an ink chamber 212, which is filled in a manner not shown here with a sponge that absorbs the ink T. The filling cannula 110 is inserted into the interior of the ink chamber 212 and penetrates it approximately halfway. The filling cannula 110 is part of a cannula carrier 104, which is positioned above the ink chamber 212. It rests on an outer container 102, which in the embodiment shown directly surrounds the ink chamber 212. However, this can also be the holder of a filling station of the type cited at the beginning, which accommodates the print head and on which the cannula carrier 104 is placed.

The ink cartridge is placed on the cannula carrier 104 in the area of a recess 112, whereby the filling cannula 110 opening into the recess 112 has penetrated the stopper 14 of the refill cartridge 1 and protrudes into the interior of the container 10. This creates a flow connection between the interior of the refill cartridge 1 and the ink chamber 212.

The cannula carrier 104 has an opening 114 in the area of the recess 112 through which the ventilation cannula 20 is guided and also penetrated into the ink chamber 212. As can be seen from Figure 2, the ventilation cannula 20 ends relatively high up in the ink chamber 212. The lower end of the ventilation cannula 20 defines the maximum fill level Pmax of the ink T to flow, as will be explained in more detail below.

The situation shown in Figure 2 corresponds to the beginning

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of the filling process, in which there is still a residual ink T in the ink chamber 212, which has a filling level of Pmin. The refill cartridge 1 that has just been put on is still practically completely filled with the ink supply T and ink begins to flow through the filling cannula 110 into the ink chamber 212. At the same time, air L is sucked through the ventilation cannula 20 into the interior of the refill cartridge 1, so that more ink T can flow out. The ink level in the ink chamber 212 rises slowly and initially reaches the lower end of the filling cannula 110 and continues to rise until the maximum filling level Pmax is reached. In this situation, ink is present at the bottom of the ventilation cannula 2 0 and thus prevents any further flow of air L. Since the interior of the refill cartridge 1 is sealed, no further ink T can flow out and the filling process stops automatically.

From the above it follows that a simple and safe filling of print heads is possible with such a refill cartridge. This simple configuration makes complex solutions superfluous and can be used universally whenever the print head to be filled has an unsealed ink chamber.

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List of reference symbols

Refill cartridge

10 container 12 cap 14 Plug 20 Ventilation cannula 2Oi Axial section 20a Axial section 102 Outer container 104 Cannula carrier 110 Filling cannula 112 deepening 114 opening 200 Printhead 212 Ink chamber L Air T ink Pmax maximum fill level; PMin minimum fill level:

Claims (9)

Dipl.-lng. KLAUS WESTPHAL * 1 &idigr;.» &idigr; Vffaicfcirasse*33 · ···, Telephone (0 7721) 56007 Dr. rer.nat. BERND MUSSGNUG .· J * I &udiagr;!-&phgr;&thgr;4$ \7s-VILfclNG£N Telex 7921573wemud Dr.-lng. PETER NEUNERT «*#···· ·* ·· ·· Fax (07721) 55164 Dipl.-lng. ROBERT GÖHRING Dr. rer. nat. OTTO B U CH N E R Mozartstrasse 8 Telephone (089):54403089 PATENT ATTORNEYS D-80336 MUNICH Fax (089) 54403080 European Patent Attorneys pmsO3 8g PROTECTION CLAIMS 1. Refill cartridge for a print head of an inkjet printer, in particular one with a single or several separate ink chambers, with a container containing ink and a stopper that can be penetrated by a filling cannula that extends into the respective ink chamber, characterized by a ventilation cannula (20) that largely penetrates the container (10) axially on the inside and penetrates the wall of the container (10) in a sealed manner on the outside, such that the end of the ventilation cannula (20) located inside the container (10) projects upwards above the level of the stored ink (T) and the opposite end is guided downwards into the interior of the ink chamber (212) and thus its position specifies the maximum fill level (Pmax) of the incoming ink (T) when the refill cartridge (1) is plugged onto the filling cannula (110). 2. Refill cartridge according to claim 1, characterized in that the ventilation cannula (20) is guided and fastened along the inside of the wall of the container (10). 3. Refill cartridge according to claim 1 or 2, characterized in that the ventilation cannula (20) can be inserted (subsequently) into the container (10). Postbank: Karlsruhe 76979-754 Bank account: Deutsche Bank AG Villingen (bank code 694 70039) 146332 V.A.T.No. DE142989261 4. Refill cartridge according to claim 3, characterized by a {further) plug which is intended to be pierced by the ventilation cannula (2 0). 5. Refill cartridge according to claim 3 or 4, characterized by an axial stop for the ventilation cannula (20). 6. Refill cartridge according to claim 3 or 4, characterized in that the ventilation cannula (20) is an integral part of a cannula carrier (104) receiving the filling cannulas (110). 7. Refill cartridge according to claim 6, characterized in that the ventilation cannula (20) is arranged immediately adjacent to the filling cannula (110). 8. Refill cartridge according to one of the preceding claims, characterized by positioning means such that the refill cartridge (1) can only be plugged onto the filling cannula (110) when it is in the correct relative angular position with respect to the print head (200). 9. Refill cartridge according to claim 8, characterized in that the positioning means also serve for color coding, such that the refill cartridge (1) can only be attached to the relevant filling cannula (110) if the color is correctly assigned.