EP1317340B1 - Cleaning unit for an ink jet printing device - Google Patents

Abstract

A cleaning unit (10) for an ink jet printer has a suction and parking cap (16) with an orifice (18), which can be placed on a print head in order to totally prevent any light from getting in.

Description

Technical field

The invention relates to a cleaning unit for a Inkjet printing device according to the preamble of Claim 1.

The problem arises with inkjet printing devices, that on the outlet nozzles and in their vicinity on the Print head will inevitably collect ink residue. This Ink residues can be left in the event that they are long enough are exposed, so that the solvents contained therein can evaporate, harden. Furthermore, when using Ink that can be cured by means of UV light is curing then occur when the ink remains due to Harden light. If this occurs, the Operational safety of the inkjet printing device is not guaranteed with the required reliability, because there may be incrustation of the outlet nozzles will adversely affect the printing result.

State of the art

A cleaning unit according to the preamble of claim 1 is known from DE 40 00 416 A1. To a trouble-free Ensure operation by the print head regularly is cleaned, a suction and is on the printhead Cover cap attached, the printhead becomes ink suctioned off and the printhead is replaced by a suitable one Facility wiped. While this known device when using solvent inks is suitable the operational safety of the ink printhead ensure exists when using inks that pass through UV light are curable, the risk of ink residue due to the incidence of UV light on the printhead harden before using the known cleaning device can be removed.

Presentation of the invention

The invention has for its object a Cleaning unit for an inkjet printing device create that even when using ink that through UV light is curable, reliably cleaning the Ensures printhead, and the training of Can prevent incrustations on the printhead.

This object is achieved by the in claim 1 cleaning unit described.

Accordingly, the cleaning unit according to the invention is like this designed a suction and parking cap an opening which is completely light-tight to a printhead can be created. This will, in addition to being able to use the ink aspirate from the printhead to crust the Nozzle outlets and uncontrolled formation of droplets at the nozzle outlet, ensures that at the Printhead before, during and after vacuuming no light, in particular, no UV light arrives, which leads to hardening of ink residue and a crusting of the nozzle outlets would lead. The measure that the printhead is light-tight the opening of the suction and parking cap can be created supported by suitable materials and Covers are used to ensure that any ink residue no light that comes to one Curing the ink would result. For example suitable covers are used so that on the Printhead when it differs from its "ordinary" Writing position moved to the cleaning unit, no UV light falls. In this context it should be noted that in Framework of the invention advantageously an extended Leadership for the carriage movement is required can be used in two ways. When using UV ink, the carriage movement must be on lengthened on both sides so that on both sides of the printing carriage attached UV lamps the printed Can also completely irradiate the area. With others Words, the printhead must be a little bit to the side of the printed area are moved so that the on the UV lamp attached over the edge area of the just printed area can be arranged. One in This way, the slide can be extended be used advantageously that the over the Edge carriage movable on at least one Arranged side on the cleaning unit according to the invention can be.

For protection against UV light, it is also used both the cover cap itself and all cables, that lead to the opening that can be made on the printhead, for example vacuum to suck the ink apply, made of opaque material be, so that here too no incidence of light can occur cause the ink residue on the printhead to harden would. It should be noted that the suction and parking cap, preferably the entire cleaning unit according to the Invention can be raised in a preferred embodiment is carried out by lifting the cap or the entire cleaning unit opening the printhead to apply. Alternatively, of course, the Cleaning unit can be permanently provided, and the print head can be designed to be lowered onto the cleaning unit.

Preferred developments of the invention are in the others Described claims.

To ensure that even in the cleaning unit itself after cleaning the print head none unwanted curing of ink or ink residues takes place, it has turned out to be advantageous to provide a cover for the cleaning unit. This is preferably motor-driven, so that it can be moved from the Cleaning unit is pushed away so that the Cleaning unit for the printhead or printheads is accessible when cleaning is to take place. alternative it is conceivable, for example, on the cover To provide a stop that allows the to go to the Cleaning unit moving print head as part of its Approach movement moves the cover.

As mentioned above, also for the invention Cleaning unit, especially for the use of Inks that are curable under UV light, preferred that suction of ink from the Ink printhead is effected. The suction is accordingly Parking cap with its opening not only light-tight on the Print head can be applied, but also in a hermetically sealed manner and way so that a vacuum suitable for suction can be created. Here it has proven to be advantageous emphasized in the hydraulic circuit that the Generation of the negative pressure is used, a delay element first Order. In other words, using a system a volume and a nozzle created to one Realize first order delay element. In detail the first order delay element consists of a Volume formed by a waste liquid bottle becomes. A choke is also provided. The system consisting of throttle and volume acts when creating one Negative pressure prevailing in a pressure tank is delaying. To The beginning is in the waste liquid bottle Ambient pressure, and the pressure in this bottle slowly drops off, so that even on the printhead from which ink is sucked off a negative pressure is slowly built up. Even if that the corresponding valve is switched off, causes the throttle a delay in the setting of normal pressure in the Waste bottle. This leads to the following Benefits. There can be a controlled rise in pressure and - Waste can be achieved and the flexible design of parts of the ink line system, for example the hoses, leads to this contract during suction and subsequently expand so that air is drawn into the lines could, and unwanted bubbles in the nozzle or the Lines are formed. It should be noted that it is the feature described above by a measure is not necessarily dealing with the inventive, light-tight applicability of the printhead on the suction and parking cap must be combined. With in other words, the provision of one unfolds First order delay element also for others Cleaning units designed for solvent inks are, its advantages, as mentioned, in an advantageous manner the suction of air into the ink lines and a Bubbles can be prevented.

A is preferred for the additional cleaning of the print head Wiping unit provided, which can be raised and lowered Deflection roller with an absorbent cloth, preferably made of Fleece. The process of cleaning the ink outlets is therefore as follows. First, ink is drawn from the Printhead sucked in at the nozzle exits set the defined ink condition. Below is the Printhead wiped through the wiping unit to remove any Ink residue that is in the vicinity of the ink spills to wipe.

On the one hand, the arrangement can be such that the top of the roller is at the printhead outlets, if it is in a wiping position. Thus touches the entire surface of the printhead outlets, and the Ink is absorbed by the absorbent cloth. this leads to for a particularly reliable wiping of the Druckkopfauslässe. In particular, the cloth can become relative move the printhead outlets so that, so to speak, over the printhead outlets are wiped. Alternatively, one Movement of the print head and the cloth causes at the same time so that the cloth covers the area of the printhead outlets completely touched, but between the print head nozzles and there is no relative movement of the cloth, so that the Nozzles are spared.

A particularly gentle and yet effective cleaning of the Print head outlets are also preferred according to those Embodiment achieved in which the apex of the Deflection roller arranged laterally next to the print head outlets is. In this case, the area of the printhead outlets not touched the whole area, but the excessive ink sucked to the side to a certain extent.

The suction and parking cap preferably has the cleaning unit according to the invention also a second Opening into which a solvent can be introduced. This is a measure that in particular Safe "parking" when using solvent inks the print head, even over a long period of time, guaranteed because the printhead outlets from solvent be washed around so that the ink does not harden can. Although the measure mentioned is basically for the Use of solvent inks is adapted and also irrespective of whether the Printhead to the suction and parking cap to considerable Benefits is training a second, with Solvent refillable opening even when using Inks that are curable under UV light for a safe Suitable for parking the printhead. The reason for this is that common inks that can be cured under UV light also contain volatile components, so they too thicken when they are protected from UV light, however, are otherwise exposed. The second described Opening into which the solvent can be introduced so that the Printhead with solvent for an extended period of time can also be flooded, a crusting of the Prevent print head outlets. In detail here is preferably a first so-called parking liquid pump provided that the parking liquid, i.e. a solvent, pumps out of a parking liquid tank into the cap. Furthermore is a second parking liquid pump available that used the Pumps parking liquid into a waste tank.

For the formation of a second opening in the suction and Parking cap has been found to be advantageous Execute cap so rotatable that either one or the other opening can be placed on the printhead. With in other words, the cap is essentially one cuboid component formed in which two different sides formed the openings mentioned are. Accordingly, the opening for suction with Vacuum can be applied, and in the other opening separate from the former opening solvent recoverable. Alternatively, the two openings of course also side by side on one plate-shaped suction and parking cap may be provided, and the cap could accordingly be designed to be displaceable be to either one or the other opening at the Print head.

Brief description of the drawings

Fig. 1

eine perspektivische Ansicht der erfindungsgemäßen Reinigungseinheit;

Fig. 2

eine perspektivische Explosionsansicht der erfindungsgemäßen Reinigungseinheit ohne Abdeckung;

Fig. 3

eine perspektivische Ansicht der erfindungsgemäßen Reinigungseinheit mit zwei daran angeordneten Druckköpfen;

Fig. 4

eine perspektivische Ansicht einer Abwischeinheit der erfindungsgemäßen Reinigungseinheit; und

Fig. 5

ein hydraulisches Schaltbild zur Darstellung einer Anordnung, die zum Absaugen von Tinte aus einem Druckkopf im Rahmen der erfindungsgemäßen Reinigungseinheit verwendet wird.

The invention is explained in more detail below on the basis of an embodiment shown as an example in the drawings. Show it:

Fig. 1

a perspective view of the cleaning unit according to the invention;

Fig. 2

an exploded perspective view of the cleaning unit according to the invention without a cover;

Fig. 3

a perspective view of the cleaning unit according to the invention with two printheads arranged thereon;

Fig. 4

a perspective view of a wiping unit of the cleaning unit according to the invention; and

Fig. 5

a hydraulic circuit diagram showing an arrangement which is used for sucking ink from a print head in the context of the cleaning unit according to the invention.

Detailed description of preferred embodiments of the invention

As shown in Fig. 1, a preferred one Embodiment of the cleaning unit 10 according to the invention a cover 12 in which four pairs of recesses 14 are formed, by which the following in more detail explained, including suction and parking caps for the printheads are accessible. In the illustrated Embodiment of the cleaning unit 10 is an embodiment for a four-color printing device is suitable, each with two printheads for printing one color are provided so that there are four pairs of Print heads result.

The cleaning unit 10 can be raised and lowered so that the print heads with their outlets through the slots 14 kick and put on the respective suction and parking cap 16 become. In the embodiment shown are in each Suction and parking cap 16 formed two openings. In which Example shown are both openings with a sealing lip 18 provided, in the case of the one opening, the suction of ink from the printhead is required that the opening with sufficient tightness to the Printhead is applied, so that suction of ink by means of negative pressure. Incidentally, this opening the cap 16 hereinafter referred to as "suction opening" 20 taken. It is assumed that the suction opening 20 in the orientation of the respective shown in Fig. 1 Caps 16 located on the top. The other opening, the hereinafter referred to as rinsing opening 22 is located on one of the sides of the cap 16 and can be seen in Fig. 2. Regarding Fig. 1 it should also be noted that a motor or cover 76 which can be displaced by means of the pressure carriage is recognizable, which is made light-tight, so that the entire cleaning unit 10 can be covered in a light-tight manner.

As can be seen in particular from FIG. 2, the Cap 16 is rotatable about a horizontal axis, so that optionally one of the two openings 20, 22 on the top can be arranged so that the cap 16 with this Opening can be applied to the printhead. As in Figs. 1 and 2 is not shown in detail, is at the suction opening 20 by suitable lines and the like leading to a Lead negative pressure source, a negative pressure can be applied. Furthermore is a solvent supply to the flushing opening 22 connected, so for example during a longer Operating break of the printhead applied to the opening 22 with Solvent can be washed around. 1 and 2 are further details of the cleaning unit according to the invention shown for the explanation of the invention no further are important. However, it should be noted that the Cleaning unit 10 can be raised to all Caps 16 simultaneously to the associated printheads to apply.

3 shows such a position for two print heads 24 shown. Of course, if the Printheads to be cleaned, also on the other three Pairs of suction and parking caps 16 associated printheads 24. At the bottom (as shown in Fig. 3) Printheads 24 are each the area of Printhead outlets that are created by attaching to the respective Opening 20, 22 arranged entirely within the opening so that the suction from all printhead outlets of ink can be made, and this according to the invention are light-tight against the environment. Also can in the event that the printheads 24 to the flushing openings 22 are created, flooding this opening with Solvents are made so that any ink residue attached to it the printheads 24 are present, solved and the training new incrustations can be prevented.

4 is a wiping unit 26 of the invention Cleaning unit shown. In the example shown the wiping unit 26 is wound on a roll 28 absorbent cloth on the various rolls up to an apex 30 of a deflection roller 34 is guided. The Vertex 30 can either be directly on the surface of the Print head outlets can be arranged, or a little sideways next to any ink residue from the printhead outlets wipe or suck off by capillary action and, in the second case, the printhead outlets at the same time to spare yourself. A gentle cleaning is also in the Case reached that the top of the cloth although flat the surface of the printhead outlets but the cloth moved simultaneously with the printhead to be cleaned is, so that there is no Relative movement sets, and the area of the Printhead outlets can be cleaned gently. The each Used sections of the cloth are on a roll 32 wound. As can also be seen in FIG. 4, is a Motor 36 present, which is connected to the belt drive Winding roll 32 is connected. There is also a motor 38 provided that the raising and lowering of the deflection roller 34th serves for this purpose on a pivotable arm 40th is stored.

5 shows an advantageous hydraulic circuit for an arrangement for sucking ink from the printheads out. Specifically, there is a first valve 42 and a second Valve 44 provided, also known as "Prime Purge Valves" or Intake / blow-out valves can be called. I'm not excited state, the two valves 42, 44 are open and connect the pump 46 to ambient pressure. In this condition the pump 46 can be started. When the first valve 42 is excited, the pump in the tank 48 creates one Overpressure. In contrast, when the second valve 44 is energized the pump 46 creates a negative pressure in the tank 48. By means of the hysteresis of two pressure sensors, one Blow-out pressure control sensor 50 and one Suction pressure control sensor 52, is by means of a Two-point control kept the pressure constant. Furthermore are a blow-out pressure sensor 54 and an intake pressure sensor 56 for Function monitoring provided. A relay 58 is used to between the two operating modes overpressure and underpressure switch. One at each of the first valve 42 and that second valve 44 connected so-called "silencer" 60 prevents annoying whistling noises.

First, an operation for filling a printhead 70 becomes written in ink. A first intake valve 62 is energized, a second intake valve 64 is not energized, and an ink waiting valve 66 is energized. Eventually a blowout valve 68 associated with the printhead 70 Cleaning unit excited. Ink is subsequently replaced by the Printhead pulled. After printhead 70 is filled this with the (not shown) device of Parking position closed, and in the tank 48 is through Switch between the first valve 42 and the second Valve 44 generates an overpressure, using a suitable one Start-up procedure is switched in between. By short Turning on the second intake valve 64 will cause air bubbles in the printhead 70 "hammered out". That way you can Air bubbles are removed from the printhead 70. It was still mentions that the ink waiting valve 66 is not energized Locks the state and prevents the ink from leaking, if the vacuum in a (not shown) tank, in which negative pressure prevails, by leaks slowly falls off.

Aspirating ink from printhead 70 in the Cleaning unit according to the invention works as follows. Through a system consisting of the volume of the Waste ink bottle 74 and a (not shown) A throttle becomes a negative pressure that prevails in the tank 48 Delay applied to printhead 70. In this Connection should be mentioned that with dashed lines in the 5 the cleaning unit of the printing carriage, which is in the upper right area of FIG. 5 is delineated. It is used for suction Blow valve 68 energized, and in waste ink bottle 74 a vacuum is built up with a delay. This Vacuum is also available for the defined suction of ink Printhead 70 on. When the blow valve 68 is turned off is, again, by the (not shown) Throttle delayed, in waste ink bottle 74 Ambient pressure.

Claims (8)

1. Cleaning unit (10) for an ink jet printer with one or more suction and parking caps (16) having an orifice (20) which can be placed on a print head (24), characterised in that the orifice (20; 22) can be placed on the print head (24) so as to totally prevent any light from getting in.
2. Cleaning unit as claimed in claim 1, characterised in that it has a light-proof cover which is preferably motor-driven or displaceable by a print carriage.
3. Cleaning unit as claimed in claim I or 2, characterised in that a vacuum pressure can be applied at the orifice (20) and a circuit for generating the vacuum pressure has a delay element of the first order.
4. Cleaning unit as claimed in at least one of the preceding claims, characterised in that it additionally has a wiper unit (26) having a deflector roll (34) with an absorbent cloth, preferably made from non-woven material, which can be raised and lowered.
5. Cleaning unit as claimed in claim 4, characterised in that an apex (30) of the roll (34) is placed on the print head outlets when the print head (24) and the deflector roll (34) are disposed in a wiping position.
6. Cleaning unit as claimed in claim 4, characterised in that an apex (30) of the roll (34) is located to the side, adjacent to the print head outlets when the print head (24) and the deflector roll (34) are disposed in a wiping position.
7. Cleaning unit as claimed in at least one of the preceding claims, characterised in that the suction and parking cap (16) has a rinsing orifice (22) into which solvent can be introduced.
8. Cleaning unit as claimed in claim 7, characterised in that the suction and parking cap (16) is rotatable so that a suction orifice (20) or the rinsing orifice (22) can be selectively placed on the print head (24).

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