EP0711668A2 - Ink refilling apparatus for ink jet cartridge - Google Patents

Abstract

The refilling system for the ink cartridge, of an ink jet printer, has a pump with a reversible flow direction. An electronic control gives a fully automatic control of the refilling operation. It activates the pump to transfer ink from the ink tank to the supply zone, until a given level is achieved. It then reverses the pump, to cancel the feed pressure and, if required, develop an underpressure in the ink supply station. The printing head is positioned in the mounting with the jet plate open upwards in the filling position. The pipe connections are flexible tubes pref. of silicon, PTFE or polyethylene.

Description

The invention relates to a device for refilling a printhead of an inkjet printer according to the preamble of claim 1.

The majority of commercially available printheads for inkjet printers are still designed as single-use products that have to be discarded after the ink supply has been used up.

This is undesirable from an ecological and economic point of view, since the used printheads are still fully functional per se and also a number of valuable components, such as the nozzle plate through which the ink is ejected or the contact foil, which provides the electrical signals for controlling the ejection process of the Ink created, contains.

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 printhead 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.

Although the refill container described there is basically suitable for refilling printheads, a number of problems arise in practical handling. For example, it cannot be prevented that ink emerges from the nozzle plate during the filling process, associated with the risk of contamination.

In order to avoid this difficulty and to generally simplify the filling process, it has also already been proposed to use special filling stations, such as are described, for example, in the previously registered but subsequently published patent DE 43 27 178 C1. These devices consist of a holder with a sealing member into which the printhead to be filled is inserted and locked. In this way, the nozzle plate located on the underside of the print head and a ventilation opening, which may be arranged adjacent to one another, are sealingly brought into contact with the sealing member. Then a with the printhead or the holder used a cannula holder provided on a cannula, so that the cannula penetrates into the ink supply space via a filling hole of the print head. A refillable cartridge which can be placed on the cannula empties into the ink reservoir after removal of a cap which closes it, so that the filling process runs automatically without further action. Various sealing elements largely prevent unintentional leakage of ink from the nozzle plate and the ventilation opening.

Although the refilling of printheads is in some cases considerably simplified with such filling stations, actuation processes which must be carried out manually are still required. In particular, this includes inserting the cannula into the interior of the ink supply space or fitting or removing the refill cartridge. Furthermore, it is necessary with these filling stations to close various openings in a certain order using suitable design measures and to open them again after filling in order to ensure that the ink flows from the attached refill cartridge under atmospheric pressure even in the case of printhead types with a sophisticated vacuum system in the ink supply chamber enable.

Devices have also become known with the aid of which the filling process can run at least partially automatically, for example from EP 0 603 910 A1, from which the invention is based. It has a holder in which the printhead to be filled can be inserted. The ink supply is located in an ink tank, which can be connected to the ventilation opening of the print head in a sealed manner via a line and a coupling piece. The apparatus further includes a pump, in the form of a double-acting piston pump, which is connected at one end to the ink tank and serves to convey ink from the ink tank into the ink supply chamber of the printhead. At the other end, the pump is connected in a sealed manner to the nozzle plate of the print head via a further line and a coupling piece, so that a negative pressure in the region of the nozzle plate and thus can be generated inside the ink supply chamber of the printhead. The double action of the piston pump now consists in that when the piston is displaced, overpressure is generated on one side, which conveys ink from the ink tank into the ink reservoir of the printhead. At the same time, a negative pressure is generated on the opposite side of the piston, which partially evacuates the ink supply space. A series of valves ensures that the return movement of the piston can take place largely without resistance, without reversing the pressure conditions.

Additional valves can be provided at different positions on a case-by-case basis in order to vary the relation and the temporal course of partial vacuum in the ink supply space on the one hand and the delivery pressure of the ink to be supplied on the other and to optimally adjust them to predetermined conditions. However, all variants are based on the basic principle of generating a partial vacuum in the ink supply space, at least in the initial phase of the filling process, in order to accelerate the penetration speed of the ink, and thus the speed of the refilling process as such. This is of outstanding importance in the printheads described there, since their ink supply chambers are filled with an open-pore foam material as a recording medium for ink, which considerably delays the penetration rate of the ink under normal printing conditions. This deficiency is remedied by at least partially lowering the pressure in the ink supply space.

A comparable solution, albeit in a different implementation, can be found in EP 0 509 687 A2. There, too, a vacuum is first created in the ink supply chamber in order to facilitate the injection of ink. In addition, however, it is provided that, following the actual filling process, negative pressure is generated by suction openings arranged adjacent to the nozzle plate in order to "prime" the print head. This is understood to mean a suction process which causes ink from the recording medium, for example the open-pore foam material, is pulled until a design-related gap between the recording medium and the nozzle plate is completely filled with ink. The print head is only ready for use when the ink is in contact with the nozzle plate and there are no air pockets in this area.

Although the devices described above can at least partially simplify the filling process, manual intervention by an operator is nevertheless required. In the case of the first-mentioned device, the pump must be operated by a hand lever, and it is also necessary to observe the refilling process and to end it by hand as soon as excess ink escapes into the collecting container. This also applies analogously to the device known from EP 0 509 687 A2, which expressly describes the manual closing of valves by an operator.

Another serious disadvantage of both devices is the high level of design complexity, in particular to control the setting and the time course of the (partial) vacuum.

The invention was therefore based on the problem of developing a device of the type mentioned at the outset in such a way that the refilling of a printhead removed from the printer was carried out directly by the user and largely without manual intervention by the operator, i.e. can be carried out automatically. At the same time, the device should be simple and inexpensive to set up and operate safely in accordance with the intended field of application in the home or in smaller offices.

This problem is solved by a device as described by the features of claim 1. Advantageous embodiments of the device are indicated by the features of the subclaims.

The invention is based on the idea of ink over one itself pumping as an aeration hole or aeration screw into the ink reservoir of the printhead under increased pressure and to let the air displaced thereby escape through the outlet openings of the nozzle plate. At the same time, the holder for the printhead is designed so that the printhead can be positioned with the nozzle plate essentially pointing upwards. The air displaced by the inflowing ink can escape directly upwards, so that foaming or blistering is excluded even with rapid ink supply under high pressure. The displaced air can be largely pushed through the outlet openings of the nozzle plate above the ink level before the rising ink level. The maximum fill level is reached when the ink level reaches the outlet openings of the nozzle plate. Positioning with the nozzle plate pointing upwards ensures that the ink supply space is completely filled in this state and practically the entire volume can be used again.

With this configuration, a filling device can be implemented with comparatively little design effort, since the evacuation of the ink supply space can be completely dispensed with. This also means no loss of functionality, since it is possible to work with a comparatively high delivery pressure. Furthermore, the air displaced through the outlet openings of the nozzle plate provides the desired cleaning effect in the region of the nozzle plate, since the air flow escaping at high speed entrains paper dust which has accumulated in the region of the outlet openings. This reliably prevents dust particles from penetrating into the inlet openings and clogging them, as occurs in the conceivable alternative, in which ink is supplied through the nozzle plate.

The use of the ventilation opening or the ventilation screw as a supply opening for the ink is not least of all advantageous because it is easily accessible from the outside of the housing of the Printhead are accessible. This eliminates the need for preparatory measures to expose any filling openings that may be present, such as the pressing in of balls serving as closure elements.

Another decisive advantage is that the print head is ready for use immediately after filling. A subsequent preparation step in the form of the priming described at the outset is omitted because, due to the positioning of the print head during the filling process, any space that may be between the recording medium and the nozzle plate is filled with ink without further action and the air therein is displaced.

Another essential feature of the device is that the filling process can be carried out fully automatically by means of control electronics. In this way, the ink is fed into the ink reservoir until the desired filling level is reached. The direction of delivery of the pump is then reversed so that the delivery pressure can be reduced and, if necessary, a predetermined vacuum can be established in the ink supply chamber. The reduction of the delivery pressure by reversing the direction of delivery accelerates the pressure equalization, so that the print head can be removed from the holder practically immediately after the desired filling state has been reached, there being no risk of contamination from residual amounts of ink present under the delivery pressure.

The reversal of the conveying direction also makes it possible to produce a negative pressure required for certain printheads in the ink supply space, without which the functionality of the refilled printhead is not or only to a limited extent.

In the concretization of the idea, an ink tank is therefore provided, which is connected to the via a line and a coupling piece Ventilation opening can be connected in a sealed manner, so that a fluid connection can be established between the ink tank and the ink supply space. In this line, a pump with reversible delivery direction is switched on, which is actuated fully automatically in the desired manner via the control electronics.

A collecting container is also provided which can be connected to the nozzle plate in a sealed manner via a line and a coupling piece, so that ink droplets which are entrained by the air escaping from the nozzle area during the filling process can be collected in a targeted manner and there is no risk of contamination. Such ink droplets often adhere to the nozzle plate itself or in immediately adjacent areas inside the ink supply space on wall areas which are swept by the displaced air, so that the droplets are inevitably entrained in the air flow.

The ink supply space of the printhead is thus sealed and integrated into a line system during the period of the filling process, in which fluid flows are generated and controlled in a fully automatic manner, and at the same time unintentional leakage of ink is avoided. The device therefore enables the automatic refilling of print heads without manual intervention.

Further advantages result if a signal transmitter is installed in the line between the nozzle plate and the collecting container, which responds as soon as ink emerges from the nozzle plate and is present in the line. This is the criterion for the ink head of the printhead to be completely full, so that the pump can be stopped. For this purpose, the signal generator is connected to the control electronics, which act on the pump in the manner described above. It goes without saying that the signal transmitter is designed such that it does not detect individual ink droplets entrained by the escaping air, but rather only responds when there is a continuous liquid column in the line just above the outlet openings of the nozzle plate.

Alternatively, a signal generator can be installed in the line between the ink tank and the vent, in the section between the pump and the vent. At the point mentioned, it measures the pressure prevailing in the delivery line for the ink before it enters the printhead. The switch-off or reversal criterion for the pump is the sudden pressure rise that occurs as a result of the throttling effect of the outlet openings of the nozzle plate as soon as the ink level is present on the nozzle plate. Because of their small diameter, the outlet openings represent a throttling point for the ink, which suddenly offers resistance to the progressing liquid front of the rising ink level. The pressure surge associated with this continues quickly against the direction of the ink and is detected by the signal transmitter. Again, the signal generator is connected to the control electronics, which act on the pump in the manner described above. In contrast to the liquid-detecting sensor described above, this signal transmitter is more cost-effective as a comparatively simple pressure sensor.

Compared to other alternatives, such as a specified delivery rate or a specific delivery period, the specified fill level can be exactly maintained so that printheads that still have residual ink in the ink supply chamber can be refilled without the risk of overfilling. Furthermore, fluctuations in the delivery rate of the ink are irrelevant, since the pump is switched off or reversed exactly at the point in time at which the ink supply space has reached the desired filling level.

Further sensors are preferably provided, which are used to monitor and / or control the filling process. It deals are liquid or flow sensors which are known per se and are integrated at various points in the lines. For example, a sensor of this type is installed in the line between the ink tank and the pump in order to monitor the ink flow. This ensures that no air is pumped into the printhead's ink reservoir if the ink tank is exhausted. In such a case, the control electronics ensure that the pump is stopped immediately and the reversal of the conveyor is initiated. This is necessary so that the print head can be easily removed and inserted into the printer even if the ink supply space is not completely filled. A display element, for example in the form of an LED or LCD, is preferably activated at the same time or an acoustic signal is triggered in order to draw attention to this operating state.

As liquid-detecting sensors, sensors are preferably installed that take advantage of the electrical conductivity of the inks used. A resistance measurement can be used to easily determine between two measuring points whether ink is present or not.

The same principle is also used for monitoring the ink leakage from the nozzle plate, the two measuring points being relatively close together in order to remove excess ink as little as possible. As described above, this sensor also triggers the reversal of the delivery direction of the pump.

The signals generated by the sensors can be used at the same time to display the respective operating states. LEDs are preferably used, which can have different flashing frequencies or different colors to identify various operating states. These can also be coupled with acoustic signals.

Furthermore, it is advantageous if a in the feed line, in particular in the section between the pump and the ventilation opening another sensor is installed that monitors the pressure in this section. This is necessary in order to prevent an inadmissible pressure increase in the event of a blocked ventilation opening or ventilation screw or blocked outlet openings in the nozzle plate area. Such an increase in pressure could, on the one hand, lead to damage or destruction of important components, or could result in heavy soiling due to sudden leakage of ink at the moment the blockage was broken. In this case too, the pump must be reversed and the operating status must be displayed.

There are particular advantages if the lines, in particular the line between the ink tank and the ventilation opening, are flexible hoses, in particular made of silicone, polytetrafluoroethylene (PTFE) or polyethylene (PE). These simplify (automatic) handling, since the coupling and uncoupling at the corresponding points on the printhead can be achieved by simply moving the coupling piece provided at the end. Such materials also open up the possibility of using a so-called peristaltic pump as a pump, in which, in contrast to the other types of pumps, no dirt or abrasion particles can come into contact with the ink. Such particles should never be put into the ink, as they can impair the function of the print head.

Furthermore, these hoses offer the possibility of monitoring the blocking states described above by clogged outlet openings and the like by monitoring the hose thickness and / or the hose diameter. In this case, a pressure build-up leads to a widening of the hose and can thus be detected by simple means such as optical sensors or the like. It is therefore not necessary to install a sensor in the line itself, rather it can be arranged outside, ie outside the ink flow.

The coupling pieces for the ventilation opening and for the nozzle plate, which are attached to the ends of the lines, are preferably formed in one piece, namely when the ventilation opening and the nozzle plate are arranged adjacent to one another in the printhead type to be filled. This is especially the case with a very widespread version, in which the housing base is step-shaped and the ventilation opening is arranged as a ventilation screw in the recessed section. The seal between the coupling piece and printhead can be achieved by a resilient portion, so that the transition from the line to the ventilation opening or to the nozzle plate is made fluid-tight for the duration of the filling process by pressing the coupling piece onto the adjacent housing wall.

The ink tank preferably consists of flexible material, namely a plastic bag, which is accommodated in a dimensionally stable housing. The housing can be designed to be foldable, so that the ink supply contained therein can be checked without problems. Although there is always the possibility of refilling the ink tank by hand, it is an advantage if it is designed to be replaceable. This is to be seen in terms of an optimal and user-friendly operation, whereby the ink tank as such only needs to be replaced at certain intervals by a new one. Depending on the planned replacement interval, the volume of the ink tank itself can be varied within further limits. It has proven to be a good compromise to choose about three to five times the amount of an original printhead (for example 120 to 200 ml), so that the ink tank and thus the device can still be extremely compact, on the other hand when used for private purposes Area or in smaller offices, the replacement intervals are sufficiently long.

The ink tank must also be designed so that it can easily receive the returned ink or the ink-air mixture when the pump is in the opposite direction.

The collecting container is advantageously at least partially filled with absorbent material, preferably with felt, sponge or a fleece, so that the ink droplets emerging from the area of the nozzle plate and the residual ink which overshoots at the end of the filling process can be safely absorbed. These are relatively small quantities; in a typical application, about 1 to 2 ml of residual ink can be expected per filling process.

The collecting container and / or the absorbent material is preferably exchangeable. In terms of simple handling, it makes sense to completely replace the collecting container including the absorbent material contained therein.

It has proven to be optimal to integrate the ink tank and the collecting container in a common housing. This enables a user-friendly device to be designed, since at the same time the waste container must be replaced when a used ink tank is replaced. Thus, the device can be brought into an optimal initial state in a single operation.

As already explained at the beginning, the nozzle plate must face upwards in order to allow the displaced air to escape during the filling process. In most cases, the nozzle plate is arranged on a step-shaped section, so that the filling process can still proceed satisfactorily even when the print head is pivoted relative to the vertical. In practice, the arrangement can be chosen so that the printhead is inclined up to a maximum of 80 ° from the vertical.

In particular when designing the device as a universal filling station that can be used for a large number of different printhead types, it is advantageous if the holder receiving the printhead can be locked in different defined angular positions. Depending on the version, it can be the optimal one Filling position can be reached. However, this requires that the bracket is designed to be pivotable.

For reasons of handling, the holder can also be designed to be pivotable in such a way that the print head has a nozzle plate pointing downwards, i.e. can be used in a position which corresponds to that in the printer itself, the holder being able to be pivoted into the filling position after insertion.

Adapters can be inserted into the holder in order to enable adaptation to different printheads. The holder itself can also be designed as an adapter, provided that it is designed to be exchangeable. The device is therefore particularly suitable for smaller offices which have different printers or different types of print heads.

The specific design of the device is largely freely selectable. It is preferably constructed from individual modules in the manner of a modular system, so that individual adaptation to different requirements is possible. This also refers to the external design that can be chosen as desired.

From a technical point of view, it is desirable to integrate the device into a housing that can be closed by a cover. The cover is coupled to the control electronics via a sensor in such a way that opening during the filling process is not possible, or the filling process is interrupted immediately if the cover should be opened. Additional measures are also possible to prevent start-up, for example, if no printhead is inserted or another component is not working properly.

With the concept described above, it is possible to implement a transportable, small filling station in the event of incorrect operation are practically excluded. It can be designed in such a way that it can be stored in any position when not in use, without ink escaping. This is mainly due to the fact that after a refill has been completed, ink is conveyed from the supply line back into the ink tank by reversing the direction of delivery of the pump, and in particular when using a peristaltic pump, it deforms the flexible line functionally to such an extent that dripping from it may still occur existing ink is prevented.

Figur 1

Schaltschema der Vorrichtung in einer ersten Variante,

Figur 2

Schaltschema der Vorrichtung in einer zweiten Ausführungsvariante,

Figur 3

Vorrichtung gemäß Figur 2 in vereinfachter Schnittdarstellung,

Figur 4

Vorrichtung gemäß Figur 2 in vereinfachter Schnittdarstellung, mit eingezeichneten Schlauchverbindungen, jedoch ohne Tintentank und

Figur 5a, 5b

Ablaufdiagramm der Steuerung.

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

Figure 1

Circuit diagram of the device in a first variant,

Figure 2

Circuit diagram of the device in a second embodiment variant,

Figure 3

2 in simplified sectional representation,

Figure 4

Device according to Figure 2 in a simplified sectional view, with drawn hose connections, but without an ink tank and

Figure 5a, 5b

Control flow diagram.

The device shown in FIG. 1 is the variant in which the presence of ink in a return line to an ink collecting container is used as the switch-off signal for the end of the delivery of ink.

A print head 100 is inserted into a holder, not shown here, in such a way that both the nozzle plate 101 and the ventilation screw 102 point upwards. The print head 100 is pivoted by approximately 70 ° with respect to the vertical. A sensor located adjacent to the printhead 100 E8 monitors whether print head 100 is inserted and is connected to control electronics 10 in a manner not shown here. The control electronics 10 has a series of LEDs 12 which signal different operating states, of which one of the LEDs 12 indicates whether the print head 100 is inserted.

An ink tank 20 is connected to the ventilation screw 102 of the print head 100 via a hose line 30. Ink is conveyed by means of the hose pump 40, which is controlled by the control electronics 10. A sensor element E9 monitors whether the ink tank 20 is inserted, sensors E4, E6 serve to monitor the ink flow in the line 30 and / or to monitor an impermissibly high pressure build-up in the ink supply space 105.

A collecting container 60 is connected to the nozzle plate 101 via a line 50. A sensor E11 monitors the presence of ink in the line 50 or on the nozzle plate 101 and triggers the signal to switch off and reverse the pump 40.

All components are housed in a housing, not shown here.

The embodiment variant shown in FIG. 2 uses the pressure jump in the delivery line as a shutdown signal, which is caused by the throttling action of the nozzle plate described at the beginning. This variant has the advantage that no ink has to emerge from the nozzle plate in order to trigger the switch-off signal. Otherwise, the design is in accordance with that of FIG. 1, so that corresponding reference numerals are used in this respect.

The print head 100 is in turn used so that both the nozzle plate 101 and the ventilation screw 102 point upwards. Sensor E8 is connected to the control electronics 10 and monitors whether the printhead 100 is inserted correctly.

The control electronics 10 have LEDs which signal different operating states, for example whether the print head 100 is inserted.

The ink tank 20 is connected to the ventilation screw 102 of the print head 100 via the hose line 30. Ink is conveyed by means of the hose pump 40, which is controlled by the control electronics 10. Sensor element E9 monitors whether the ink tank 20 is inserted.

The collecting container 60 is connected to the nozzle plate 101 via the hose line 50. Ink tank 20 and collecting container 60 are integrated in a common housing 22.

The control electronics 10 is built on a circuit board 11, which in itself accommodates all monitoring elements and a number of actuating elements.

Two buttons E1, E2 serve as operating elements, the button E1 starting the filling process, whereas button E2 enables the locking of a protective flap or cover described in more detail below.

Displays A4, A5, A6, A7, A8, A9 are provided for displaying various operating and fault states, which can be designed as LEDs 12 according to FIG. 1. Display element A4 indicates when the power supply is connected and the operating voltage is present. This state is indicated by flashing at a frequency of approximately 2 Hz. As soon as a printhead is properly inserted and all other starting conditions, which will be explained in more detail below, are met, the display changes to permanent light. This indicates that the filling process can begin by pressing the start button E1.

The display element A5 signals that it is possible to open the protective flap or cover, for example for inserting or removing the print head 100.

The display element A6 indicates whether a filling process is in progress. During the filling process, the display element A6 flashes at a frequency of approximately 2 Hz.

The display elements A4, A5, A6 indicate correct operating conditions and are therefore green.

The display element A7 is a warning signal which indicates that the ink supply in the ink tank 20 is exhausted. It is designed in yellow and flashes at a frequency of 2 Hz.

The display element A8 responds if the print head 100 should be blocked, for example in the area of the nozzle plate 101. The display is at a frequency of 2 Hz and is red.

The display element A9 is designed as a general error warning and responds when a fault is to be reported elsewhere.

Furthermore, pressure switches E3, E4, E5, E6, E7 are arranged on the board, which are connected to the delivery line 30 and control the filling process in the form of signal transmitters.

The pressure switch E3 responds as soon as the ink supply space 105 is filled with ink. It is therefore designed such that it detects the pressure increase described at the outset due to the throttling action of the nozzle plate 101.

Print switch E4 monitors whether print head 100 is clogged.

The pressure switch E5 monitors the reduction of the delivery pressure after the filling process.

The pressure switches E6 and E7 check the fill level of the ink supply in the ink tank 20.

The sensors E3, E4, E5, E6, E7 are therefore those which are designed as pressure switches and thereby monitor the ink flow.

The sensors E8, E9 and another sensor E10, which detects the locking of the protective flap or cover described in more detail below, are designed as limit switches.

The device shown in Figures 3 and 4 shows the concrete implementation of the concept shown in Figure 2.

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

The circuit board 11 is fastened to the upper housing part 71. The button E2 for opening the protective flap 79, the pressure switch E3 for detecting the switch-off signal, a light-emitting diode 12 and the sensor element E10 for monitoring the protective flap 79 can be seen in the selected sectional plane. For reasons of clarity, the illustration of the electrical interconnection and wiring has been omitted in both figures, since this is known per se.

A holder 75 is arranged below the protective flap 79, in which the print head 100 is inserted with the nozzle plate 101 inclined upwards. The presence of the print head 100 is detected by the sensor element E8. The nozzle plate 101 and the ventilation opening 102 are sealed by the holder 75 against an overflow nozzle 81 and a filling nozzle 80 for producing a sealed fluid connection to the collecting container 60 and ink tank 20.

Collecting container 60 and ink tank 20 are accommodated side by side in a common housing 22 which can be inserted into the lower housing part 70. The correct position of the housing 22 is monitored by the sensor E9. Still is a double cannula 91 is present which, when the housing 22 is inserted, penetrates into the interior of the ink tank 20 and into the interior of the collecting container 60 and enables the desired fluid connection. To protect against injuries from the cannula 91, the lower housing part 70 is closed in the insertion region of the housing 22 with a protective flap 78 which pivots upwards when the housing 22 is pushed in and folds downwards when the housing 22 is pulled out.

The fluid connection from the ink tank 60 to the ventilation opening 102 of the print head 100 is realized by a hose line 30, which is attached to the cannula 91 via a hose distributor 90 and on the filler neck 80 opposite. The hose line 30 is designed in one piece as a continuous line, since the ink is conveyed by the hose pump 40, which acts on the hose line 30 from the outside in a manner known per se. The peristaltic pump 40 is driven by a pump motor 45.

However, the line 30 is interrupted in the section between the hose pump 40 and the filler neck 80 by a hose distributor 92 in order to provide information about the pressure conditions at this point to the sensor elements, such as E3 or E4. Hose lines 31, 32, which are arranged between the hose distributor 92 and the sensor elements E3, E4, are used for this purpose.

The hose line 50 establishes the fluid connection between the nozzle plate 101 and the collecting container 60. Hose lines 33, 34 are also provided, which in turn serve to transmit pressure information and are therefore connected at one end to the hose distributor 90 and at the other end to sensor elements (E6, E7).

Finally, a locking pin 14 is provided in the lower housing part 70, which can be actuated by a locking magnet 15.

It serves for the safety locking of the protective flap 79.

FIGS. 5a and 5b show the simplified flow chart for the automatic control of the filling process.

By pressing the start button (button E1) the program is started, which first checks whether the requirements mentioned at the beginning are met. If a system error is found, it is displayed (display element A9).

As far as all input requirements are met, the protective flap 79 can be opened. The print head 100 is then inserted and the protective flap 79 is closed again. If there is ink in the device and all other safety conditions are met, the filling process can be started.

The filling process is monitored by sensor elements (in particular pressure switches E3, E4, E5, E6, E7), which are queried repeatedly in sequence and cyclically. If there is a fault condition, the pressure reduction in the delivery line (line 30) is initiated and a system error is displayed.

If the filling process is carried out correctly, this is completed by a subsequent leak test. The determined state is then displayed and the pressure in the delivery line 30 is reduced. The protective flap 79 can then be opened and the printhead 100 removed. The printhead 100 can thus also be removed if it is recognized during the visual check that the printhead 100 should be blocked. For this purpose, the display element A8 is provided, which indicates this state by a flashing signal.

As a further safety aspect, a time limit for the filling process is provided. If the specified time has elapsed before the filling process is completed, a system error will occur detected and the filling process interrupted.

It follows from the foregoing that with the aid of the concept according to the invention it is possible to implement a fully automatic filling station which offers the highest degree of operating comfort and safety.

Reference list

10th

Control electronics

11

circuit board

12th

LED

14

Locking pin

15

Locking magnet

19th

Power supply socket

20th

Ink tank

22

casing

30th

management

31

management

32

management

33

management

34

management

40

pump

45

Pump motor

50

management

60

Collecting container

70

Lower part of the housing

71

Upper part of the housing

75

bracket

78

Safety flap

79

Protective flap

80

Filler neck

81

Overflow nozzle

90

Hose distributor

91

Cannula

92

Hose distributor

100

Printhead

101

Nozzle plate

102

Ventilation opening

105

Ink supply room

A4

Display element

A5

Display element

A6

Display element

A7

Display element

A8

Display element

A9

Display element

E1

Button

E2

Button

E3

Sensor element

E4

Sensor element

E5

Sensor element

E6

Sensor element

E7

Sensor element

E8

Sensor element

E9

Sensor element

E10

Sensor element

E11

Sensor element

146

Claims (20)

Device for refilling an ink jet printer printhead outside the ink jet printer that the pump puck, with the printhead having an ink supply space, which is in fluid communication with outlet openings of a nozzle plate and is ventilated via a ventilation opening, with a holder in which the print head can be inserted, an ink tank which can be connected in a sealed manner to the ventilation opening via a line and a coupling piece in order to produce a fluid connection, a pump for conveying ink from the ink tank into the ink supply room, a collecting container for ink emerging from the nozzle plate, which can be connected in a sealed manner to the nozzle plate via a line and a coupling piece in order to establish a fluid connection, characterized, that the pump has a reversible delivery direction, - That control electronics for fully automatic control of the filling process is present, which acts on the pump in such a way that the ink is conveyed from the ink tank into the ink storage space until the desired filling level is reached and then reverses the direction of delivery of the pump, so that the delivery pressure is reduced and, if necessary, a predetermined negative pressure in the ink storage space can be manufactured, and - That the print head can be positioned in the holder with the nozzle plate (filling position) essentially pointing upwards. Apparatus according to claim 1, characterized by at least one signal transmitter, which is installed in the line between the nozzle plate and the collecting container, and which responds as soon as ink is present in the line, so that the delivery of ink from the ink tank into the ink supply chamber via the control electronics is ended. Apparatus according to claim 1, characterized by a signal transmitter which is installed in the line between the ink tank and the ventilation opening in the section between the pump and the ventilation opening and which responds to a sudden increase in pressure due to the throttling action of the nozzle plate as soon as the ink delivered into the ink supply space largely fills this and is in contact with the nozzle plate, whereupon the delivery of ink from the ink tank is stopped via the control electronics. Device according to one of the preceding claims, characterized in that the ink tank consists of flexible material, preferably a bag. Apparatus according to claim 4, characterized in that the ink tank is integrated in a dimensionally stable housing. Device according to one of the preceding claims, characterized in that the ink tank is exchangeable. Device according to one of the preceding claims, characterized in that the collecting container is at least partially filled with absorbent material, preferably with felt, sponge, non-woven material. Device according to one of the preceding claims, characterized in that the collecting container is exchangeable. Device according to one of the preceding claims, characterized in that the ink tank and the collecting container are integrated in a common housing. Device according to one of the preceding claims, characterized in that the lines are flexible hoses, preferably those made of silicone, polytetrafluoroethylene (PTFE) or polyethylene (PE). Apparatus according to claim 10, characterized in that the pump is a peristaltic pump. Device according to one of the preceding claims, characterized in that the coupling piece for the ventilation opening and the coupling piece for the nozzle plate are designed as a one-piece coupling piece. Device according to one of the preceding claims, characterized in that the print head in the filling station is inclined relative to the vertical in the range between 0 ° and 80 ° and is positioned with the nozzle plate pointing upwards. Device according to one of the preceding claims, characterized in that the holder can be pivoted in such a way that the print head can be inserted from above with the nozzle plate pointing downwards and then pivoted into the filling position. Device according to one of the preceding claims, characterized in that the holder can be locked in different, defined angular positions. Device according to one of the preceding claims, characterized in that adapters for adapting to different print heads can be inserted into the holder, or the holder itself is designed as an adapter. Device according to one of the preceding claims, characterized by a housing which can be closed with a cover or safety flap. Apparatus according to claim 17, characterized in that the cover or safety flap is coupled to the control electronics such that the filling process cannot be started if the cover or safety flap is not completely closed. Apparatus according to claim 17 or 18, characterized in that the cover or safety flap is coupled to the control electronics in such a way that the pump is reversed immediately if the cover or safety flap is opened prematurely, so that the delivery pressure is reduced and, if necessary, a predetermined vacuum in the ink reservoir can be manufactured.

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