EP0829362A2 - Method for filling ink cartridges or printing head for an ink jet printer or the like - Google Patents

Abstract

The method involves making a sealed fluid connection between the nozzle plate (101) and an ink tank (20). Ink is fed from the ink tank through the outlet opening (102) of the nozzle plate into the ink reservoir (105) in cycles with alternate operation and stopping of a feed pump (40). The delivery of ink to the reservoir is stopped when a certain switch-off criterion is reached. Ink is returned into the ink tank until a defined vacuum pressure is reached in the reservoir, then the fluid connection is removed.

Description

The invention relates to a device for refilling an ink cartridge or a print head of an inkjet printer according to the preamble of claim 1, and a device suitable for this.

The majority of commercially available ink cartridges or printheads for inkjet printers are still designed as a disposable product that must be discarded after the ink supply has been used up. This is undesirable from an ecological and economic point of view, since the used ink cartridges or printheads are still fully functional per se and also a number of valuable components, such as a nozzle plate through which the ink is ejected, or a contact foil that controls the electrical signals for control of the ink ejection process.

For this reason, proposals have already become known for refilling such print heads by means of suitable measures and thus extending their service life. In the simplest case the print head can be refilled by hand through a bellows-like refill container, as is known, for example, from WO 92/20 577. For this purpose, the refill container has a hollow needle which is inserted through a ventilation opening in the housing of the printhead and thereby inserted into the ink supply space. By pressure on the bellows-like, elastically deformable section of the refill container, the ink contained therein is pumped into the ink reservoir.

To improve handling, it has also already been proposed to use special filling stations such as are described, for example, in DE 43 27 278 C1. These devices consist of a holder with a sealing member into which the printhead to be filled is inserted and locked. As a result, the nozzle plate located on the underside of the print head and a ventilation opening, which is optionally arranged adjacent to one another, are sealingly brought into contact with the sealing member. A cannula holder provided with a cannula is then placed on the printhead or the holder used, so that the cannula penetrates into the ink supply space via a filling hole in the printhead. A refillable cartridge which can be placed on the cannula empties after removal of a cap which closes it, so that the refilling process takes place automatically without further action.

Finally, a device has become known from EP 0 711 668 A2, with the aid of which the refilling process is carried out in a fully automated manner. It has a holder in which the print head can be inserted. When inserting the printhead, a sealed connection between the ventilation opening on the printhead and the ink tank, on the one hand, and between the nozzle plate and a collecting container for ink emerging from the nozzle plate, on the other hand, is established via a coupling piece. Furthermore, a pump for conveying ink is provided, which is actuated by control electronics in such a way that the ink remains in the ink tank for as long as Ink supply space is promoted until the desired fill level is reached. The direction of delivery of the pump is then reversed so that the delivery pressure can be reduced and, in addition, a predetermined vacuum can be established in the ink supply chamber. By accommodating the print head with the nozzle plate essentially pointing upward, the air displaced by the supplied ink can escape upwards directly through the outlet openings of the nozzle plate. The maximum filling state is therefore predetermined by the presence of the ink level at the outlet openings of the nozzle plate. This means that a filling device that can be operated reliably can be implemented with comparatively little design effort.

The refill devices described above have in common that they presuppose the presence of a fill opening or at least one ventilation opening on the printhead through which the ink to be refilled can be supplied. In practice, however, a large number of ink cartridges or print heads are used which do not have such a refill or ventilation opening or whose access from the outside is not readily possible. Access to the ink supply space of these ink cartridges or printheads is therefore only provided through the outlet openings of the nozzle plate.

The possibility of using the previously known refill devices fails in the above-mentioned first cases because the cannulas cannot be passed through due to the small diameter of the outlet openings of the nozzle plate in order to guide the ink into the ink supply space. In the case of the latter fully automatic filling station, the problem arises that in order to implement the fluid system used there, the printhead must be accessible via two separate openings, namely the outlet openings of the nozzle plate and the ventilation opening.

The invention was therefore based on the problem of a method to refill an ink cartridge or a printhead of an inkjet printer, and to provide a device suitable for this purpose, in which only a single access opening to the ink supply space is required, in order in particular to be able to operate such ink cartridges or printheads that do not have a refill opening or ventilation opening or the like Accessibility would only be possible with great effort.

The problem is solved, on the one hand, by the features of the method described in claim 1, advantageous method variants are specified by the subsequent related claims.

The problem is further solved by a device which is described by the features of claim 12. An advantageous embodiment is specified by the features of the subordinate claim.

The invention is based on the idea of supplying ink to the ink supply space in cycles by alternately starting and stopping a feed pump. The cyclic operation (pulsed operation) of the feed pump ensures that, in those cycle sections in which the pump is stopped, sufficient pressure equalization between the ink supply space and the supply area in front of the nozzle plate can take place through its outlet openings after an excessively high pressure build-up. This procedure enables optimal delivery of ink without special additional measures, since the delivery pressure of the delivery pump as such does not have to be regulated. A wide variety of boundary conditions during operation, for example the current fill level of the ink cartridge or the printhead, pressure ratios of the vacuum system provided in the ink supply space, flow conditions and / or flow resistances in the area of the outlet openings of the nozzle plate can be compensated without problems, without having to regulate the delivery pressure of the feed pump, as is the case here in a continuous Funding would be necessary during the entire filling process.

The control device which influences the feed pump thus only needs to implement two switching states, namely the starting and stopping of the feed pump in an alternating sequence, with any measurement variables per se being able to be used as a criterion or triggering signal for the respective switching operation. The control unit evaluates the corresponding signals in a manner known per se and influences the desired operating state of the feed pump as a function of the calculated result. An additional control, for example in the form of a speed control of the drive motor for adapting the delivery capacity, can be completely dispensed with, so that a particularly simple construction of a device can be implemented.

Finally, the concept is also suitable for redesigning the fully automatic filling station described at the beginning with a few modifications and largely using identical components, and thus for achieving a device which can also be used without restriction, or only with restrictions, for the ink cartridges or printheads in question here Ensure access to the ink supply chamber through openings other than those of the nozzle plate. Compared to the known fully automatic refilling device, only the control device has to be modified so that the desired interval operation of the feed pump is implemented. With regard to the construction, one of the two lines is also omitted, namely the one that had to be connected to the ventilation opening. Overall, a device can be created that is extremely simple and inexpensive.

The easiest way to implement interval operation is to monitor the pressure in the delivery line in the area in front of the nozzle plate. The feed pump is activated when a predetermined upper threshold value is reached stopped and put into operation again when a predetermined lower threshold value is reached. The pressure curve resulting from this is essentially sawtooth-shaped, ie it rises to the upper threshold value after the feed pump has been started and then drops to a predetermined lower threshold value, ie after the feed pump has been stopped. This cycle repeats itself until a specified switch-off criterion is met.

The advantage of this operating mode can be seen in the fact that only a single measurement signal is required, namely the prevailing pressure in the delivery line in the area in front of the nozzle plate. The measurement signal can be generated by using commercially available and inexpensive pressure sensors. At the same time, the specification of the threshold values, in particular the upper threshold value, ensures that even in the event of malfunctions, an impermissibly high pressure build-up with the risk of damage to the system cannot occur. If, for example, the outlet openings of the nozzle plate are blocked, pressure will build up very quickly when the feed pump is started for the first time, but its maximum value is limited by the specification of the upper threshold value, although the maximum feed pressure of the feed pump can be much higher. Additional monitoring of the system pressure can therefore be omitted.

With regard to the choice of the threshold values there is essentially free movement, whereby on the one hand it must be ensured that the upper threshold value is not chosen too high in order to avoid leakage problems. So it has proven to be expedient to choose a pressure in the range of approximately 0.8 to 1.0 bar overpressure as the upper threshold value. On the one hand, this pressure is sufficiently high to enable ink to be conveyed rapidly into the ink supply space, on the other hand, it does not place too high demands on the sealing elements and connecting / coupling pieces used.

A pressure in the range between approx. 0.0 and 0.2 bar gauge pressure has proven itself as the lower threshold value. If the shortest possible refilling process is to be implemented, it is advisable to select a value as the lower threshold value which is somewhat higher than 0 bar, since the decay process to a "depressurized" state requires a relatively long time. As a good compromise, values between approx. 0.1 and 0.2 bar overpressure have proven to be the lower threshold.

Further preferred process variants are directed towards the selection of a suitable switch-off criterion.

In the simplest case, the expiry of a time interval is used as the switch-off criterion. Advantageously, this is dimensioned such that the (purely arithmetically) conveyed ink during this time interval approximately corresponds to the nominal receiving volume of the relevant ink supply space. Filling volumes are specified by the ink cartridge or printhead manufacturers, which can serve as a measure for a quantity of ink to be refilled. The required time interval can thus be determined from the mean value of the rising and falling pressure curve, approximately as an arithmetic mean between the upper and the lower threshold value, and taking into account the delivery data of the pump, the density of the ink and the cross sections of the outlet openings of the nozzle plate.

In practice, it has been shown that an exact matching of the time interval to the nominal recording volume is desirable, but is not absolutely necessary. On the one hand, most of the commercially available ink cartridges or printheads are designed in such a way that they can accommodate a larger volume than the nominal recording volume without loss of function. Overfilling in the range of up to 25% above the nominal recording volume seems to be possible with a number of ink cartridges or printheads. On the other hand, in the case of the preferred threshold values, the maximum would be reached prematurely Filling status before the expiry of the time interval, for example in the case of a print head which is only partially written empty, does not pose any danger to the system since the pump, if necessary repeated, is stopped when the upper threshold value signal is reached. This corresponds to the condition of clogged outlet openings, since here too (further) delivery of ink is no longer possible.

The switch-off criterion is preferably the expiry of a time interval which is determined as a function of the number of cycles which is reached within a predetermined time interval at the beginning of the refilling process, preferably during the first 60 seconds. As a result, different starting conditions and the associated effects on the filling quantity are taken into account. If there are larger air inclusions in the system, which is formed by the ink tank, the fluid connection (line) to the nozzle plate and the ink supply chamber (for example when the device is started up for the first time), the system behavior becomes sluggish. The reason for this is that the trapped air is first displaced in the direction of the ink supply space and acts as a compressible cushion towards the delivered ink. It goes without saying that in the case of an extended cycle duration, for example as a result of the inclusion of air described, the time interval for the entire refilling process must be extended in order to achieve the desired refill volume. For this reason, the number of cycles is determined during a defined period of time at the beginning of the refilling process and extrapolated from this to the total time required for the delivery of the nominal ink volume.

The switch-off criterion is preferably monitored as to whether the pressure prevailing in the area in front of the nozzle plate has dropped to the lower threshold value before a predetermined time interval has elapsed. The time interval begins anew each time the feed pump is stopped due to the upper threshold being reached. As soon as the capacity of the ink reservoir is exhausted, no more ink can pass through the outlet openings of the nozzle plate. As a result, the current pressure level is largely retained, and it is no longer possible to drop to the lower threshold. This "getting stuck" at a pressure level above the lower threshold value can thus be used reliably as a switch-off criterion. A time period is expediently chosen as the time interval which is approximately two to three times as long as the time period for the pressure to drop from the upper to the lower threshold value with a largely empty ink supply space.

According to a further preferred variant of the method, the switch-off criterion is used to monitor whether the pressure in the area in front of the nozzle plate has reached the upper threshold value before a predetermined time interval has elapsed, the time interval starting anew each time the feed pump is started as a result of the lower threshold value being reached. So while the pressure drop of the cycle was monitored in the previous embodiment variant, the pressure increase is analyzed in the present case. It has been shown that the period of time shortens with increasing filling level of the ink supply space, in particular shortly before the maximum filling level is reached. A safe switch-off criterion can be considered if, according to a preferred variant, the upper threshold value is reached after 90 to 95% of the time period which is required for such an increase in the case of an essentially empty ink supply space.

Those variants which monitor the pressure development in the rising and / or falling branch with each new cycle are particularly suitable when the filling status of the ink cartridge or the printhead is not known or when ink cartridges or printheads which are not written empty are frequently to be refilled. In the simplest case, a fixed time interval would also be sufficient for the entire refilling process in order to ensure that refilling takes place safely to leave, however, this procedure seems uneconomical, since in any case, ie even with small amounts of ink to be refilled, the entire time interval must always expire. Different shutdown criteria are therefore preferably linked to one another, for example the criterion of the time interval extrapolated at the start of the filling process for the entire process in combination with the monitoring of the pressure drop in each cycle. This makes it possible to shorten the filling process when the ink cartridge or the printhead still contains significant amounts of ink, for example when refilling it before a larger print job is processed.

• eine Halterung, in die die Tintenpatrone oder der Druckkopf einsetzbar ist,
• einen Tintentank, der über eine Leitung und ein Kopplungsstück mit der Düsenplatte zum Herstellen einer Fluidverbindung abgedichtet verbindbar ist,
• eine Förderpumpe mit umkehrbarer Förderrichtung zum Fördern von Tinte aus dem Tintentank in den Tintenvorratsraum sowie
• eine Steuereinrichtung, die den Befüllvorgang steuert und auf die Förderpumpe einwirkt.

A device suitable for carrying out the method must therefore have the following modules as a minimal configuration:

• a holder in which the ink cartridge or the print head can be inserted,
• an ink tank, which can be connected in a sealed manner to the nozzle plate for establishing a fluid connection via a line and a coupling piece,
• a delivery pump with reversible delivery direction for delivering ink from the ink tank into the ink supply space as well
• a control device that controls the filling process and acts on the feed pump.

A pressure sensor, the signal of which is evaluated by the control device, is preferably switched on in the line in the region adjacent to the nozzle plate of the ink cartridge to be used or of the print head to be used.

Figur 1

Vorrichtung in vereinfachter Schnittdarstellung,

Figur 2

Druckverlauf während des Befüllvorgangs und

Figur 3, 3a, 3b, 3c

Ablaufdiagramm der Steuerung.

The invention is explained in more detail below with reference to the exemplary embodiments shown schematically in the figures. Show it:

Figure 1

Device in a simplified sectional view,

Figure 2

Pressure course during the filling process and

Figure 3, 3a, 3b, 3c

Control flow diagram.

The device shown in FIG. 1 enables the procedure according to the invention and is therefore to be explained in advance.

The entire device is housed in a two-part housing, consisting of a lower housing part 70 and an upper housing part 71, which accommodate all components.

A circuit board 11 is fastened to the upper housing part 71, on which control electronics (not shown in more detail here) are installed and which also accommodates all monitoring elements and a number of actuating elements. In the sectional plane shown here, a button E2 is shown as one of two actuating elements, which releases the locking of a hinged protective flap 79 attached to the housing part 71. Immediately next to it is a further button, not shown, with which the filling process can be started.

Adjacent to the circuit board 11, a light-emitting diode 12 is shown on the upper housing part 71, several of which are combined to form a display field and signal different operating and fault states. Specifically, the light emitting diode 12 indicates whether the protective flap 79 is closed.

For the sake of clarity, the electrical wiring and wiring have not been shown, since this is known per se.

A holder 75 is arranged below the protective flap 79, in which a print head 100 is inserted. This is a printhead 100 with an ink supply space 105 arranged inside, which is provided in a manner known per se with a vacuum-producing device, for example in the form of spring-loaded ink bags. A nozzle plate 101 provided with outlet openings 102 is arranged on the front side of the print head 100. The presence of the print head 100 is detected by a sensor element E8.

By inserting into the holder 75, the nozzle plate 101, including the outlet openings 102 provided therein, are pressed in a sealed manner against a filler neck 80, in which a line 30 opens in a sealed manner. An ink tank 20 provided with a housing 22 can be inserted into the lower housing part 70.

Adjacent to this, a hose distributor 90 provided with a cannula 91 is arranged on the lower housing part 70, so that when the ink tank 20 is inserted, the cannula 91 penetrates into the interior of the ink tank 20 in a fluid-tight manner. Opposite is attached to the hose distributor 90, the line 30, so that a sealed against the environment fluid connection between the inside of the ink tank 20 on the one hand and the filler 80 or the ink reservoir 105 of the printhead 100 used on the other hand is made. The line 30 is designed as a flexible hose line and per se continuous between the hose distributor 90 and the filler neck 80. A hose pump 40 driven by a pump motor 45 is provided for conveying ink and acts on the hose line 30 from the outside in a manner known per se. The hose pump 40 is locked on the lower housing part 70.

Two lines 33, 34 are provided on the hose distributor 90, which transmit pressure information to a sensor element E3 for the purpose of monitoring in a manner not of interest here.

However, line 30 is in the section between the peristaltic pump 40 and the filler neck 80 are interrupted by a hose distributor 92 in order to obtain information about the pressure conditions in the line 30 at this point, ie in the region adjacent to the nozzle plate 101, and to transmit them to the sensor element E3. Hose lines 31, 32, 35 are used for this purpose. The information obtained is transmitted in a manner known per se to the control electronics (not shown), which acts on the hose pump 40 or the pump motor 45 driving it in the manner described in more detail below, and also the the proper course of the refilling process is monitored.

The basic principle of the procedure according to the invention is indicated by the pressure / time diagram sketched in FIG. 2, which shows the course of the pressure in the hose line 30 in the section between the hose pump 40 and the filler neck 80, that is to say adjacent to the nozzle plate 101. In a departure from previously known methods, the peristaltic pump 40 is alternately switched on and off by the control electronics during the duration of the filling process, so that the sawtooth-like pressure curve shown in FIG. 2 is generated in the hose line 30. The pump 40 is activated for the duration of a time interval T1, as a result of which the pressure in the line 30 increases. The increase in pressure is hereby largely determined by the flow resistance of the outlet openings 102 of the nozzle plate 100. This is so high that T1, i. H. within a few seconds, the pressure reaches an upper threshold Po, whereupon the pump 40 is stopped.

The pressure then drops again, since no further ink is conveyed and the ink under pressure in line 30 is pushed further through the outlet openings 102. The pressure reduction also takes place within a comparatively short time T3, which is usually in the range of seconds.

When the lower threshold value Pu is reached, the pump 40 is started again, whereupon the pressure rises again to the upper threshold value Po within the time interval T1. The cycle, consisting of the pressure increase and the subsequent pressure drop, starts again, the cycle time resulting from the addition of the time intervals T1 and T3.

The cycle is repeated until one of two switch-off criteria is reached.

In the present exemplary embodiment, the expiry of a predetermined time interval T6 has been reached as the first switch-off criterion, so that the feed pump 40 is prevented from being started again. In the constellation shown, the maximum filling state is not (completely) reached when the time interval T6 has elapsed, which generally does not lead to any practical disadvantages. The basic constellation is accordingly indicated, in which the ink supply space 105 no longer contains any significant ink residues, so that the intended ink volume can be completely introduced during the time interval T6.

In the exemplary embodiment shown, the elapse of the time interval T6 coincides with the elapse of the last subinterval T3, so that the current pressure in the line 30 has just reached the lower threshold value Pu at this point in time. It goes without saying that the expiry of the time interval T6 does not necessarily have to coincide with the expiry of the subinterval T3 in practice, but usually takes place at a different (time) location, that is to say also within the subinterval T1 during the pressure build-up phase . In such a case, the feed pump 40 is stopped immediately, so that the upper threshold value Po is no longer reached in this cycle.

When the switch-off criterion is reached, the delivery direction becomes - after the delivery pump 40 has possibly been stopped beforehand reversed and the feed pump 40 for returning ink into the ink tank in operation. The return of ink serves on the one hand to rapidly reduce the overpressure present in line 30 and on the other hand to produce the (slight) underpressure in ink supply space 105 required for the printhead to function properly. As soon as the required negative pressure is reached, the feed pump 40 is stopped and the print head 100 can be removed from the device ready for operation.

FIG. 2 also indicates the response of a further switch-off criterion, in which it is monitored whether the pressure in line 30 has dropped to the lower threshold value Pu before a certain predetermined time interval T3, max has elapsed. For this purpose, the maximum permissible time interval T3, max is restarted each time the feed pump 40 is stopped as a result of the upper threshold value Po having been reached. If the pressure has not dropped to the lower threshold value Pu when the time interval T3, max has elapsed, this is regarded as a criterion for the fact that, despite the pressure applied to the nozzle plate 101, no further ink can flow into the ink supply space 105, i.e. it is completely filled is. Here too, the refilling process is brought to an end by reversing the direction of delivery of the feed pump 40, so that the pressure reduction and the subsequent restoration of the desired negative pressure in the ink supply space 105 can take place.

When choosing the maximum time interval T3, max, care must be taken that this is chosen so long that on the one hand premature termination of the refilling process is avoided and on the other hand there are no long waiting times. It has proven to be a good compromise to choose about two to three times the subinterval T3, which occurs in an average case with a largely empty ink supply space 105. For the sake of completeness, it should be pointed out that the partial intervals T1 and T3 can change from cycle to cycle within certain limits, in particular, if air pockets occur in line 30, or just before the maximum fill level is reached. As explained in more detail at the beginning, the latter effect can also be used as a switch-off criterion.

The combination of the above switch-off criteria enables a particularly economical procedure, since in the case of such print heads which still have significant residual volumes of ink, the refilling process can be specifically completed when the intended filling state is reached.

FIGS. 3a, 3b and 3c show the simplified flow chart for the automatic control of the refilling process.

Pressing the start button (button E1) establishes the power supply and first checks whether the input requirements have been met. If a system error is found, it will be reported.

If all input requirements are met, the protective flap 79 can be opened. Thereupon the print head 100 is to be inserted, possibly also the ink tank 20. After the protective flap 79 is closed, the filling process is started.

When the pump 40 is started, two time intervals start, namely the time interval T6, which specifies the maximum duration of the filling process, and the further time interval T3, max, which monitors the pressure increase when the first cycle is completed. If the upper threshold value Po designated as “pressure level P2” is not reached within the predetermined time interval, there is a system error. In normal cases, however, the upper threshold value Po is reached in good time and the pump 40 is switched off. In the first cycle, a leak test is additionally carried out, which stops the refilling process in the event of a detected leak and, by reversing the feed pump 40, initiates the pressure reduction and the required negative pressure in the Ink supply room 105 produces.

Insofar as the tightness criterion is met positively, the time interval T3 is started immediately when the feed pump 40 is switched off, and it is monitored whether the lower threshold value Pu referred to as “pressure level P1” is reached within the maximum intended time interval T3, max. If this is the case, the feed pump 40 is started again and the cycle begins again.

The cycle is now repeated until either the lower pressure level (threshold value Pu) is no longer reached during the maximum predetermined subinterval T3, max or the maximum predetermined filling time T6 has expired.

Then, by reversing the conveying direction, ink is conveyed back into the ink tank 20 until the overpressure in the line 30 is completely reduced and then the intended underpressure in the ink supply space 105 is reached. After a short waiting time for an internal pressure equalization, the protective flap 79 can be opened and the print head 100 can be taken ready for operation.

Reference list

11

circuit board

12th

led

20th

Ink tank

22

casing

30th

management

31

management

32

management

33

management

34

management

35

management

40

Peristaltic pump

45

Pump motor

70

Lower part of the housing

71

Upper part of the housing

75

bracket

79

Protective flap

80

Filler neck

90

Hose distributor

91

Cannula

92

Hose distributor

100

Printhead

101

Nozzle plate

102

Outlet openings

105

Ink supply room

E2

Button

E3

Sensor element

E8

Sensor element

Max

Maximum value

P

pressure

Butt

upper threshold

Pu

lower threshold

T1

Time interval

T3

Time interval

T6

Time interval

Claims (13)

Method for refilling an ink cartridge or a printhead of an inkjet printer or the like, with an ink supply space which receives the ink and is in fluid communication with outlet openings of a nozzle plate and in which there is a negative pressure which prevents unintentional leakage of ink through the outlet openings of the nozzle plate,
characterized by at least the following process steps: a) Establishing a sealed fluid connection between the nozzle plate (101) and an ink tank (20). b) conveying ink from the ink tank (20) into the ink supply space (105) in cycles by alternately starting and stopping a feed pump (40). c) stopping the delivery of ink when a predetermined switch-off criterion is reached. d) returning ink to the ink tank (20) until the specified negative pressure in the ink supply space (105) is reached. e) Loosening the fluid connection. Method according to claim 1, characterized in that the pressure prevailing in the area in front of the nozzle plate (101) monitors and the feed pump (40) in each case - stopped when a predetermined upper threshold value (Po) is reached, and - put into operation when a predetermined lower threshold value (Pu) is reached becomes. Method according to claim 2, characterized in that the upper threshold value (Po) lies in the range between approximately 0.8 and 1.0 bar overpressure. Method according to Claim 2 or 3, characterized in that the lower threshold value (Pu) is in the range between approximately 0.0 and 0.2 bar overpressure. Method according to one of the preceding claims, characterized in that the expiry of a time interval (T6) is used as the switch-off criterion. Method according to Claim 5, characterized in that the time interval (T6) is dimensioned such that the delivered ink approximately corresponds to the nominal receiving volume of the ink supply space (105). A method according to claim 5, characterized in that the time interval (T6), depending on the during a certain time interval at the beginning of the refilling process, vzw. during the first 60 seconds, the number of cycles reached is determined. Method according to one of Claims 2 to 7, characterized in that the switch-off criterion is monitored whether the pressure prevailing in the area in front of the nozzle plate (101) has dropped to the lower threshold value (Pu) before a certain time interval (T3, max) has elapsed, the time interval (T3, max) restarts each time the feed pump (40) is stopped as a result of the upper threshold value (Po) being reached. A method according to claim 8, characterized in that the time interval (T3, max) is approximately two to three times the time period (T3) which elapses in the case of an essentially empty ink supply space (105) until the pressure after the feed pump has stopped ( 40) drops from the upper threshold (Po) to the lower threshold (Pu). Method according to one of Claims 2 to 7, characterized in that the switch-off criterion is monitored as to whether the pressure prevailing in the area in front of the nozzle plate (101) has reached the upper threshold value (Po) before a certain time interval (T1, max), whereby the time interval (T1, max) restarts each time the feed pump (40) is started as a result of the lower threshold value (Pu) being reached. Method according to Claim 10, characterized in that the time interval (T1, max) is approximately 90 to 95% of the time period (T1) which elapses in the case of an essentially empty ink supply space (105) until the pressure comes on after that the feed pump rises from the lower threshold value (Pu) to the upper threshold value (Po). Device for refilling an ink cartridge or a printhead (100) of an inkjet printer or the like, with an ink supply space (105) which receives the ink and is in fluid communication with outlet openings (102) of a nozzle plate (101) and in which a predetermined negative pressure prevails prevents inadvertent leakage of ink through the outlet openings (102) of the nozzle plate (101), for carrying out the method according to one of the preceding claims, with a holder (75) into which the ink cartridge or the print head (100) can be inserted, an ink tank (20) which can be connected in a sealed manner to the nozzle plate (101) via a line (30) and a coupling piece (50) in order to establish a fluid connection, - A feed pump (40) with a reversible conveying direction for conveying ink from the ink tank (20) into the ink reservoir (105), and - A control device controlling the filling process, which acts on the feed pump (40). Apparatus according to claim 12, characterized by a pressure sensor which is switched on in the line (30) in the region adjacent to the nozzle plate (101) of the ink cartridge or the print head (100) to be used.

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