EP1317342B1 - Ink jet printing device - Google Patents

Description

The invention relates to an ink jet printing device for media, as described in the preamble of claim 1, and a method for printing on media.

There are a variety of inkjet printers known - US 6,092,890 A . EP 0 842 051 1 B1 . DE 4 019 543 A . DE 3 417 376 A which have proven themselves for a wide variety of applications. The inkjet printers are suitable for the printing of a variety of media, such as paper, plastic films, especially with different absorbency and porosity. Each of these media requires a different approach. A disadvantage was therefore that such devices were each suitable only for a specific medium.

From the document DE 195 32 724 A1 , which can be considered as the closest prior art, is a multi-color printing device with a printing unit consisting of a Tinfenstrahldruckkopf known, with the objects of different heights can be printed. For this purpose, an adjustment of the distance of the printing unit to the receiving surface of the objects to be printed is provided in this device. This is made possible on the one hand by a height-adjustable platform of the transport carriage for receiving the object and on the other hand by a sensor which detects the position of the surface of the object to be printed.

The US 6,005,593 A describes a printing device of the type of ink jet printer for recording images on paper, plastic films or the like. The sheets of the printing medium are thereby moved by a feed or a transport device below the print head which can be moved back and forth transversely to the transport direction, the print medium being supported in the area below the print head by the guide surface of a support plate. In order to eliminate a jam of the print medium in the area below the printheads, is provided in this printing device that the lower conveyor rollers of the transport device can be lowered together with the pressure medium supporting the support plate and so the space between the printheads and this support plate is increased.

The JP 10 157 245 A describes a printing device for printing on boxes. It is provided that a box is transported on a guide surface and through each other opposite printheads two sides of the box can be printed simultaneously. The box is guided between a lateral guide surface on one side and a movable guide surface on the other side, wherein the distance between the printheads and the respective side surfaces of the box can be regulated by pressing the movable guide surface in the direction of the fixed guide surface.

From the US 5,717,446 A a transport device for an inkjet printer is described with a pressurizable conveyor belt. The application of vacuum to the conveyor belt, on the one hand, causes the pressure medium to be held thereon. With the vacuum hold-down device, however, it is also possible to rinse the ink jet print head in which - in the absence of a print medium - ink is sucked through the openings of the conveyor belt.

In the thermal printer according to the JP 5 294 020 A the printing medium is moved between a thennoprinting head and a support roller, wherein the distance between the printhead and the support roller can be regulated according to the thickness of the printing medium.

In the US 5,815,282 A there is described a printing apparatus for printing on profiled surface articles such as audio cassettes using an ink jet head as the printhead. The printing device has a sensor by which the distance of the print head to the surface of the object to be printed can be measured. By a control device, the print head is adjusted in the vertical direction based on the distance detected by the sensor, so that the distance between the print head and the surface of the object to be printed can be kept constant.

From the US 5,854,643 A For example, a printing device is known in which the distance between the print medium guide plane and the print head can be kept constant. The position of the management level is determined by two support rollers over which an endless conveyor belt for the pressure medium is guided. The support rollers can be adjusted in their relative position to the print head, the transport device being equipped with a mechanism which ensures that the tension of the endless conveyor belt can be kept constant.

In the WO 99/47354 A1 there is disclosed an ink jet printing apparatus for printing on textiles. The textile fabric is fed to the printing device in the form of wound on rolls fabric webs. For stepwise further transport of the textile material, the printing device is formed with a transport device, wherein the fabric web is guided around a movable roller, so that the fabric web forms a loop and is kept taut. By determining the position of the deflection roller by means of a detector, it can be automatically ensured that a sufficient length of the fabric web is unwound from the roll in good time and conveyed to the area of the print heads in good time:

The invention is based on the object; to provide an ink jet printing device that can be used flexibly for a variety of media. In addition, it should be possible to adapt the inkjet printing device with a small conversion effort to another print medium with different properties.

The solution of this object is achieved by the ink jet printing apparatus according to claim 1. It is advantageous in this case that it is now possible with an ink jet printing device substantially inherently rigid, plate-shaped media such. Corrugated board or corrugated board blank, board boards that are not processable by the roll to directly print plywood, compound, plastic and metal panels. This opens the possibility for the first time to produce machines with which the most diverse materials such as paper, fabric, cardboard, metal can be directly printed.

Advantageous is a variant according to claim 2, since it allows different thicknesses of media to be processed.

Advantageous is the development according to claim 3, since even with respect to the length of the medium short support surface or guide surface in the inkjet printing device proper guidance of intrinsically stiff media of greater length is possible.

But it is also a development according to claim 4 possible, whereby even in relation to the length of the medium short support surface or guide surface in the field of inkjet printing device kinking semi-rigid media is prevented.

Suitably, a variant according to claim 5 or 32, as a result of damage the printing device or the production of defective prints can be avoided.

Advantageous are the developments according to claims 6 to 10, as this is a simple and accurate lateral positioning intrinsically rigid media which can take over the lateral guide pressure is achieved.

However, an advantage is also achieved by the configuration of the inkjet printing apparatus according to claim 11, as it is a conversion to different media, such as fabrics, paper webs, cardboard or plastic elements is easily possible.

A sensitive control of the feed movement and / or the orientation of the medium is achieved by the embodiment according to claim 12.

In the embodiment according to claim 13, a sensitive effect on the medium to be printed is possible because, according to the type and consistency of the medium, such as intrinsically rigid materials or flimsy materials, the rollers are used multiple times. For exact guidance and smoothing of the medium to be processed, the embodiments according to claim 14 and 15 are suitable.

Also advantageous is the development according to claim 16, since it can be ensured over a larger area a uniform feed rate. In addition, a feed without counter-pressure rollers is possible and therefore pressure-sensitive or very flexible and sensitive materials can be processed.

The perfect height guidance of the medium in the range such a tape feed can be achieved by the developments according to claims 17 to 22.

It is advantageous in the embodiment according to claim 23 that the extent of an intermittent feed movement on the displacement of the dancer roller can be controlled exactly.

Also advantageous is an embodiment according to claim 24 and 25, since thus in the support surface for the medium at any time a Absorbtionsvorrichtung for excess ink can be used.

Also advantageous are the embodiments according to claims 26 to 29, since in ink-jet printing devices that were set up for processing flexible media, the processing of plate-shaped elements made of different materials, such as cardboard or plastic, is possible.

The further embodiments according to claims 30 and 31 allow with advantage that media can be processed at the beginning and / or end of the same need not cover the entire guide surface in the feed direction of the medium.

The ink jet printing device according to the invention is characterized in that it can be used to print both roll and sheet media, both flexible and stiff, as well as impermeable and porous media, since the distance between the medium and the printhead assembly or the printhead and the respective nozzle for each color can be adjusted individually to the predeterminable conditions. In other words, the one or more push buttons or nozzles with respect to a printing table or its support surface or the top of the media are mounted so that they in relation to the distance from the printing table and thus from the medium to be printed and / or the lateral orientation of the medium are flexibly adjustable. This makes it possible that with the aid of the inkjet printing device according to the invention media of different thickness can be printed. Furthermore, the ink jet printing device according to the invention is due to this feature for guiding media with different properties in different ways, especially in a height adapted to the properties of the medium over the printing table and in one qualitatively consistent and reliable way to print.

By the preferred embodiment according to claim 33, a fully automatic Einjustieren the printing device to different media thickness can be easily made, whereby it is possible to determine before the start of the printing process, if the thickness of the introduced medium matches the preset value to misprints damage to the printing device to prevent. The avoidance of errors when inserting the different media can be further improved by the embodiments of claims 34 to 37.

Advantageously, the embodiment according to claim 38, whereby over the entire printing process sufficient monitoring of the desired distance is possible and in case of deviations either the pressure is interrupted or corrective measures can be initiated.

Through the development according to claim 39 it is ensured that a preselected distance to achieve an optimum printing result, regardless of the movements and / or deformations of the medium can be maintained exactly, so that even on slightly deformed or not plan resting parts of a medium a corresponding print quality can be achieved.

Furthermore, an embodiment variant according to claim 40 is advantageous since it allows a rapid zeroing or system device to be achieved when printing different media.

A further development according to claim 41 is also advantageous, since precise control for each nozzle of a print head or a printhead arrangement is thus possible, and therefore also different adjustments corresponding to the physical behavior of the respectively used color, with regard to their consistency or viscosity, can be taken into account.

The development according to claim 42 makes it possible to ensure a uniform printing of a flat surface forming medium.

But is also advantageous embodiment according to claim 43, since characterized by a uniform Construction of the machine different media can be printed.

In the development according to claim 44 is advantageous that thus an exact distance between the printhead assembly, the printing table or its support surface but also on the top of the medium by a single measurement between printhead assembly and the surface of the medium or by a composite measurement of the support surface or can be calculated or determined from the printing table to the surface of the medium and the distance between the printing table and the printhead assembly.

A more individual adaptation of the print heads to the surface of the medium to be printed or the printing table, in particular in a flat support surface for guiding the medium in the printing area, is achieved by the embodiment according to claim 45.

An exact positioning of the nozzles and a perfect inking is achieved by the further embodiment according to claim 46, as this allows individual adjustment of each nozzle in their distance from the surface of the medium or the printing table.

The further developments according to claims 47 to 49 make it possible for the respective media used to be printed to have a corresponding exact determination of the actual value of the distance.

Further variants of the embodiment of the distance sensor can be taken from claims 50 and 51, wherein the distance can be determined directly by assembling different partial measuring values or by the interaction of the parts of the distance sensor due to the different arrangement of the distance sensors consisting of several parts.

An advantage is also an embodiment according to claim 52, as this determines the movement of the nozzles of the printhead or the printhead assembly before producing a line of printing and thus the process, especially the movement of the nozzle or the printhead or the printhead assembly , can be controlled more sensitively.

The developments according to claims 53 to 55 allow a rapid change of the setpoint and a sensitive, high-precision control with extremely fast Reaktionsver like by using an electronic calculator.

Also advantageous is an embodiment according to claim 56, since thereby the basic distance of the printhead assembly depending on the thickness of the medium and the position of the printing table - depending on whether a Tintenabsorbtionseinrichtung is provided below the medium or not - are set.

By the configuration according to claims 57 to 65, a flexible in all directions setting and adjustability of the individual parts of the ink jet printing device is achieved. Of course, it is also possible to provide only individual drives and guide arrangements, however, any of the aforementioned adjusting devices and guide arrangements can be used in combination with each other.

An exact guidance of the medium also with different thicknesses of the medium and with different additional devices, such as an ink absorption device is made possible by the development according to claim 66.

Another advantage is also an embodiment according to which it is provided that this ink jet printing device supports a tape edge sensor and the medium roll on a roller bearing vertically and transversely to the feed device and leads, which is adjustable via the actuator in the axial direction, as thus flexible materials or materials that can not accommodate side guide pressure, accurate positioning can be ensured in the application area of the jet inkjet printing device. Thus, a processing of substances is possible.

It has proven to be advantageous in this case a further development, according to which the tape edge sensor is arranged in the region of the print head arrangement, or directly upstream thereof, since changes in the lateral position can be recognized in good time, as may affect this in the area of the printing device A machine can be created with which a variety of flat media can be flexibly, rigidly, impermeably or porous processed.

However, the object of the present invention can also be achieved by the method according to claim 67.

The fact that now a single fixed machine can be used by the semi-rigid or inherently stiff media, such as cardboard, plastic plates, metal plates or the like. Can be printed in passing, is a cost-effective production of imprints of large-scale illustrations on intrinsically rigid materials different surface quality whether porous or nichtaugend possible and can be characterized by the production of thin adhesive films, which must then be laminated on such rigid components, save.

Especially in the processing of media of very different thickness, an approach according to claim 68 or 69 is advantageous, since thereby the emergence of faulty groups or damage to the machine by different thickness media is avoided with certainty.

The method according to claim 70 makes it possible to process intrinsically stiff media which are substantially larger than the support or guide surface in the area of the inkjet printing device.

A preferred independent solution of the problem is also possible by the method according to claim 71. It is advantageous that the print quality can be achieved by monitoring the thickness in a simple manner.

Advantageously, it can be ensured in the procedure according to claim 72 that at the beginning of the printing process, the inkjet printing device or its nozzles in the impeccable for a high quality, important distance above the surface of the to be printed Mediums are arranged. Damage caused by confusion of the medium to be introduced in the inkjet printing device can be avoided by the measures of claim 73.

If the medium roll, adjusted according to the measures in claim 74, as well as an exact lateral positioning of the medium is possible and is both in the longitudinal direction and in the transverse direction, a borderless printing of media possible.

Misprints due to undesired lateral relative adjustment between the medium and the print head can be avoided by the procedure according to claim 75.

Even media with different thickness or spatial distortions or changes can be printed in a procedure according to claim 76 with high quality.

A same print image even over media of great length, can be achieved by the procedure of claim 77 and / or 78.

For exact feed mark a procedure according to claim 79 or 80, whereby the banding in the production of such prints on large areas can be reliably avoided.

The invention will be explained in more detail with reference to the embodiments illustrated in FIGS.

Fig. 1

eine Seitenansicht der erfindungsgemäßen Tintenstrahl-Druckvorrichtung beim Bedrucken von Papier als Rollenmedium;

Fig. 2

eine Seitenansicht der erfindungsgemäßen Tintenstrahl-Druckvorrichtung beim Bedrucken von flexiblem Stoff als Rollenmedium;

Fig. 3

eine Seitenansicht der erfindungsgemäßen Tintenstrahl-Druckvorrichtung beim Bedrucken eines plattenförmigen Mediums;

Fig. 4

eine Draufsicht auf die erfindungsgemäße Tintenstrahl-Druckvorrichtung;

Fig. 5

eine Draufsicht auf einen Abschnitt der erfindungsgemäßen Tintenstrahl-Druckvorrichtung;

Fig. 6

ein Detail der Tintenstrahl-Druckvorrichtung mit einem Sensor, gemäß Fig. 1;

Fig. 7

eine vereinfachte Prinzipdarstellung einer Tintenstrahl-Druckvorrichtung;

Fig. 8

ein Detail der Druckkopf-Anordnung einer Tintenstrahl-Druckvorrichtung in geschnittener Darstellung, gemäß Fig. 7;

Fig. 9

ein Detail einer Tintenstrahl-Druckvorrichtung mit einem Schlitten, in geschnittener Darstellung;

Fig. 10

ein Detail eines Druckkopfs mit einer Halterung in geschnittener Darstellung; gemäß Fig. 9;

Fig. 11

einen Schnitt mit einer Anordnung einer Vorschubwalze, Gegendruckwalzen und Seitenführungsbahnen, gemäß Fig. 3;

Fig. 12

einen Schnitt einer Anordnung aus einer Vorschubwalze und einer Gegendruckwalze, gemäß Fig. 11;

Fig. 13

ein Detail einer Rollenlagerung für eine Mediumrolle, gemäß Fig. 5.

Show it:

Fig. 1

a side view of the ink-jet printing device according to the invention in printing paper as a roll medium;

Fig. 2

a side view of the ink-jet printing device according to the invention when printing flexible material as a roll medium;

Fig. 3

a side view of the ink-jet printing device according to the invention in printing a plate-shaped medium;

Fig. 4

a plan view of the ink-jet printing device according to the invention;

Fig. 5

a plan view of a portion of the ink-jet printing apparatus according to the invention;

Fig. 6

a detail of the ink jet printing apparatus with a sensor, according to Fig. 1 ;

Fig. 7

a simplified schematic diagram of an ink-jet printing device;

Fig. 8

a detail of the printhead assembly of an ink jet printing device in a sectional view, according to Fig. 7 ;

Fig. 9

a detail of an ink jet printing device with a carriage, in a sectional view;

Fig. 10

a detail of a printhead with a holder in a sectional view; according to Fig. 9 ;

Fig. 11

a section with an arrangement of a feed roller, back pressure rollers and side guide tracks, according to Fig. 3 ;

Fig. 12

a section of an arrangement of a feed roller and a counter-pressure roller, according to Fig. 11 ;

Fig. 13

a detail of a roller bearing for a medium roll, according to Fig. 5 ,

As in Fig. 1 1, the ink-jet printing apparatus 10 according to the invention has, on the one hand, a base body 12 which is fastened to a machine frame 11 and on which various rollers, which are described in more detail below, are mounted. Further, a printhead assembly 14 having a plurality of indicated printheads 16, mounted in a frame construction on the base body 12 and raised, so that the height of the printheads 16, for example, for printing differently thick media can be adapted in a suitable manner. In the embodiment shown is located both on the feed side (according to Fig. 1 the right side) and on the removal side a hinged mounted table 18 which is provided with a plurality of guide elements forming rollers 20 and further in its according to the folded-up position lower portion has a hinged portion 22 which is hinged about a hinged axis 24 upwards so that in the table 18, so to speak creates a window through which the ink jet printing apparatus 10 is also accessible from the supply and the withdrawal side. In Fig. 1 the two tables 18 are shown in a folded-up position, since, as will be explained in more detail below, a situation is shown in which the printing of a roll medium takes place. If, however, what with reference to the Fig. 3 will be described to print media in sheet or plate form, the two tables 18 are pivoted to a horizontal position, so that by the tables 18, which can also be referred to as supports, a supply of plates can be done, even then if they are comparatively heavy, can be handled easily.

With reference to Fig. 1 Let us first describe how printing of roll media takes place in the ink-jet printing apparatus 10 according to the invention. In the lower right area of the Fig. 1 is a medium roll 26 to recognize, which is stored in a manner to be explained below in a roller bearing. Starting from the medium roll 26, the roll medium is first guided via a deflection roll 28 to a feed roll 30. Starting from the feed roller 30, the medium 101 passes under a dancer roller 32, which is pivotably mounted via an arm 34. Below the dancer roller 32 is a sensor 36, which cooperates with this in the manner explained below. Downstream of the dancer roller 32 is a so-called brake roller 38, which is therefore referred to as a brake roller 38, because it does not rotate in the transport direction, especially in the printing of flexible media, but opposite to this. In other words, as shown in FIG Fig. 1 the rotation of the brake roller 38 in the clockwise direction as the medium 101 moves from right to left through the inkjet printing apparatus 10, and the feed roller 30 rotates counterclockwise.

For the relative position of components of the ink-jet printing apparatus 10, reference will be made to the direction of movement of the medium 101 in the further description. Downstream is the movement of the medium 101 of the media roll 26 via the guide roller 28, the feed roller 30, the dancer roller 32, the brake roller 38 and finally under the print heads 16 away, the further movement on the transport roller 46 to the roller 56 and Unloading 58 are understood, this direction is referred to as the feed direction 137. In contrast, the movement in the opposite direction and, correspondingly, spatial references of the arrangement of parts of the inkjet printing apparatus 10 with upstream shall be referred to.

Similarly, the side of the ink-jet printing apparatus 10 on which the medium roll 26 is disposed is also referred to as the medium supply side and the side of the ink-jet printing apparatus 10 opposite to the medium roll 26 as the medium discharge side and the discharge side, respectively become.

For the flexible use of the ink-jet printing device 10 according to the invention, it has also proven to be advantageous to combine at least one roller, for example the feed roller 30, the brake roller 38 or the transport roller 46, with a counter-pressure roller which can be brought into and out of engagement. The counter-pressure roller can act with the associated roller as a transport or feed roller. This is particularly necessary for particularly heavy, plate-shaped media, which by a below, in the description of the Fig. 4 , belt drive described in more detail are no longer readily transportable. For the transport of such media, the counter-pressure roller can thus be brought into engagement with a roller described as a transport roller, and provide for the required transport. In the event that the feed can be done in another way, since another medium 101 is present, the counter-pressure roller can be pivoted out of engagement, for example, in a suitable position.

In the present case, for example, both above the feed roller 30 and the brake roller 38 a pivotally mounted counter-pressure roller 40 and 42 are arranged, where the medium 101 is pressed. In this case, the paper is tensioned in the area of the dancer roller 32. This flexible applicability of the different rollers can meet the different requirements that are placed on different media to be printed become. For example, by a different operation of a feed roller 30, the different requirements that are imposed when printing a flexible compared to a comparatively rigid medium 101, are taken into account in an optimal manner.

For example, the inkjet printing device 10 according to the invention makes it possible to use a separately controllable roller when printing comparatively less flexible paper as feed roller 30 in order to advance the paper at given times by a defined feed length.

Conversely, if a flexible medium 101, such as cotton, is to be printed, the same roll, i. the feed roller 30, which is operated when printing paper as a feed roller, not driven, but it stands still and thus acts as a guide device. As a result, the flexible fabric is transferred from a transport roller 46 over the stationary roller, i. the feed roller 30, pulled and always kept tight or "ironed". In this case, the stationary roller, i. the feed roller 30, are further operated so that it is rotated at a distance of, for example, a few minutes by a small angle, so that the wear of the feed roller 30 through the fabric which is drawn over this, takes place uniformly over the circumference of the roller. Thus, according to the present invention, by providing a plurality of separately controllable rollers, it is possible to adjust the movement of the medium 101 to be printed by the ink jet printing apparatus 10 to different conditions in connection with different kinds of media, so that the ink jet printing apparatus 10 of the present invention is versatile can be used.

It should be added that the inkjet printing device 10 according to the invention leads to the decisive advantage that different media can be printed with one and the same device, whereby the necessary changeover processes can be accomplished quickly. This thus allows operation of the user of the ink-jet printing apparatus 10 according to the invention, which advantageously meets today's requirements, since there is an increasing demand that a wide variety of media, such as e.g. in the field of advertising for one and the same project are required to print.

In the area of the print heads 16, a tape feed 44 is arranged, which consists of several circumferential Bands 72, and its exact operation below in the detailed description of Fig. 4 is described.

Downstream of the described area of the printing heads 16 and the printing table 110 is a transport roller 46, which brings the medium 101 in the correct position with respect to the printing heads 16 in cooperation with a counterpressure roller 48 and this in particular via the braking roller 38 rotating in the opposite direction pulls to smooth it, and apply a defined voltage to the medium 101. It can be seen that on the one hand above the transport roller 46, the counter-pressure roller 48, and laterally from the transport roller 46, a counter-pressure roller 50 is provided. The upper counter-pressure roller 48, in cooperation with the transport roller 46, serves to transport plates in a horizontal direction, ie to the table 18 folded in this case in the horizontal position Fig. 1 As shown, a roll medium is to be printed, which in turn is roll on a roll 52 in the printed state, the lateral counter-pressure roller 50 is in engagement with the transport roller 46 and ensures the transport.

Downstream of the transport roller 46 is a cutter 54, with the aid of which a roll medium can be cut to produce rollers 56 of smaller circumference than that of the medium roll 26 on the feed side of the ink jet printing apparatus 10. In Fig. 1 is indicated that such, smaller rollers 56 may be mounted in an upper region of the device. In contrast, when the printed medium 101 is to be wound on a comparatively large roller 52 in the final state, it is stored in the ink jet printing apparatus 10 according to the invention in a lower region. From there, such a roller 52, which can not usually be handled and carried by a single operator, be removed from a loading and unloading device 58, the subject of Application WO 02/22478 the applicant. Also for the feed side (according to Fig. 1 right) is to be mentioned that here the loading can be accomplished with a medium roll 26 by such loading and unloading device 58. Further, further roller bearings may be provided on the feed side, so that in higher areas of the inkjet printing apparatus 10 unwinding of a roll medium of relatively small rollers 56 can be carried out.

The operation of the ink-jet printing apparatus 10 according to the invention in the printing of flexible media such as paper and synthetic fabrics, works as follows. The medium 101 is pulled substantially through the transport roller 46 via the printing table 110. It is useful here if the tape feed 44 with the, in the following in the detailed description of Fig. 4 , suction openings described at least for the plan holding the medium 101 was used. He can also support the feed or the medium 101. The printing takes place each stripwise with a stripe width of for example 70 mm. Accordingly, the transport of the medium 101 must be intermittent. In this case, the medium 101 is pulled by the transport roller 46 in cooperation with the counter-pressure roller 48, as described, on the counter-rotating brake roller 38, so that the medium 101 always remains taut. As a result, it further maintains its rigidity, and the distance of the medium 101 to the outlet surface of the printhead nozzles is kept constant, which is essential for ensuring a good printing result.

After each printing operation, the feed roller 30 advances the medium 101 so far until the dancer roller 32 in the in Fig. 1 shown, reaches deep position, in which a arranged below the dancer roller 32 sensor 36 is actuated. This indicates that the required feed length has been reached, and a controller 120 stops the feed roller 30. Subsequently, the material for positioning for the next printing operation of the transport roller 46 is further pulled, so that the dancer roller 32 is raised. In the subsequent feed operation by the feed roller 30, the material is in turn advanced so far that the dancer roller 32 is lowered and abuts the sensor 36.

With regard to the flexible design of the entire transport device of the ink-jet printing device 10 according to the invention, it has proved advantageous to associate a roller, which is operated in connection with certain media as a feed roller 30, with a dancer roller 32. Such a dancer roller 32 is attached to an arm 34 which is pivotally mounted on the base body 12. In particular, according to a preferred embodiment of the invention, such a dancer roller 32 is combined with a sensor 36 such that a lowered position of the dancer roller 32 caused by the feed is detected by the sensor 36 and generates a signal indicative of a defined feed length. In other words, in such an operation of the inkjet printing apparatus 10 of the present invention, a transport roller 46 disposed downstream of the printing table 110 transports the medium 101 to the area of the printing heads. This feed must be done in a defined manner so that the intermittently printed strips on the medium 101 are in a correct position relative to each other. For the defined Feed is made in accordance with the described preferred embodiment of the invention in that subsequent to the transport of the medium 101, which biases the medium 101 and thus raises the dancer roller 32, a feed takes place, the bulge of the medium 101 down, inter alia, under the effect the gravity of the dancer roller 32 causes. This occurs until the bulge is sufficiently large, and the position of the dancer roller 32 is sufficiently deep, so that the medium 101 meets the described sensor 36, which subsequently detects and signals that the required feed length has been reached. A control device 120 stops the feed roller 30 for this purpose.

To produce a defined feed length by an intermittent feed movement of the medium 101, along the guide surface 130, a loop of the medium 101 is formed by the dancer roller 32, so that the medium 101 is advanced in the advancing direction 137 until a distance perpendicular to the guide surface 130 of the medium 101 corresponds to an extent of the subsequent, intermittent advancing movement of the medium 101 via the guide surface 130, whereupon the medium 101 is held on the side of the loop remote from the guide surface 130 and relative to the guide surface 130 in the longitudinal direction of the medium 101 by a presettable amount of the distance of the loop is moved forward.

In Fig. 6 For example, a detail of the ink jet printing apparatus 10 is illustrated with an alternative embodiment of the sensor 36 associated with the dancer roller 32. As already in the figure description of Fig. 1 In this case, the medium to be printed 101 is passed under the dancer roller 32. The medium 101 moves thereby from the feed roller 30 and the corresponding counter-pressure roller 40 coming under the dancer roller 32 and on via the brake roller 38 and the corresponding counter-pressure roller 42 in the direction of the printhead assembly 14 (FIG. Fig. 1 ), wherein the medium 101 by the dancer roller 32, which is movably mounted on the arm 34, is tensioned. The determination of the exact feed length of the medium 101 is thereby signaled by the sensor 36, which is formed in this case as a light-optical sensor. The sensor 36 is preferably formed by a photoelectric arrangement, wherein the radiation of one part of the sensor 36 is partially shielded by the sinking dancer roll 32 and the medium 101, which can be detected at a second part of the sensor by a photoelectric receiver. The corresponding signals are used by a controller 120 to determine the required feed length of the medium 101.

In Fig. 2 For example, the situation when printing on a flexible and porous medium 101, for example, cotton cloth used as a flag material is shown. Since this is a porous medium 101 through which the ink used for printing at least partially passes, care must be taken that the underlying printing table 110 is not contaminated. This is done according to the invention by an insertable ink absorber consisting of an ink absorbing pad 60 and two supporting edges 62 arranged laterally therefrom. The Tintenabsorbtionseinrichtung is used in a, in the region of the receiving surface of the printing table 110 in a receiving device. These supporting edges 62 are inserted into the printing table 110 and serve for the defined guidance of the medium 101 at a defined height above the printing table 110. Any ink which passes through the porous medium 101 is absorbed by the ink absorbing pad 60 extending across the printing table 110 ,

Further, in the ink-jet printing apparatus 10, e.g. also possible to provide a liftable and lowerable printing table 110. As a result, different circumstances which occur when printing different media can also be taken into account. For example, the printing table 110 may be lowered to allow the insertion of an ink absorber provided in the ink jet printing apparatus 10 of the present invention. Also, the useable ink absorber makes the ink-jet printing apparatus 10 of the present invention flexibly usable because it can be used with ease in printing porous media such as cloths, thus ensuring safe and clean operation of the ink-jet printing apparatus 10. Furthermore, impermeable media such as e.g. Paper to be printed borderless with the ink-jet printing apparatus 10 according to the invention, since any ink that is discharged beyond the edge of the medium 101, is received by the ink absorber. As mentioned, the elevating and lowering press table 110 enables the rapid insertion of such an ink absorber and moreover ensures that the position of the press table 110 can also be adjusted according to the requirements of the type of medium 101 to be printed.

Accordingly, since the medium 101 to be printed is at a changed height, the printhead assembly 14 containing the printheads 16 must be slightly elevated, which is described in US Pat Fig. 2 is shown and can be seen by the fact that, for example, the feed roller 30 associated counter-pressure roller 40 in a relation to the situation of Fig. 1 is raised position. Thus, the printheads are located also in the case that the medium to be printed 101, as in the case of cotton fabric, is pulled over the supporting edges 62, at a defined height above the medium 101 to be printed, so that the printing result can be secured in qualitative terms. Alternatively or additionally, the printing table 110 may be formed lowered, which is provided according to the invention and also provides space for the insertion of the supporting edges 62 and the ink absorption pad 60.

The intermittent feed, in the printing of fabric, is again accomplished by the transport roller 46 through engagement with the platen roller 48, which pulls the media 101 over the brake drum 38. The separately controllable feed roller 30 is not used in this case, however, before the advance of the medium 101, but stands still. As a result, the medium 101 is pulled over the stationary feed roller 30, which causes a certain ironing effect. Thus, the abrasion of the stationary in this case feed roller 30 is not carried out at a single point, this feed roller 30 is rotated at regular intervals by a few degrees, so that the abrasion is uniform over the circumference. At this point, it becomes apparent how the ink-jet printing apparatus 10 according to the invention can be used flexibly for different media due to the separate controllability and the separate operating possibilities of the individual rollers. It should be additionally mentioned that the ink absorbent pad 60 can be used together with the support edges 62 also in non-porous media when they are to be printed borderless, which necessarily leads to at least a slight over-edge spraying. Accordingly, the ink discharged over the edge can be sucked up by the ink absorbing pad 60, and the printing table 110 can be kept clean.

In Fig. 3 It is shown how the ink-jet printing device 10 according to the invention can be converted for the printing of cardboard plates to a certain weight per unit area. Up to a certain basis weight, the feed of the cardboard plates namely by the tape feed 44, the exact operation of which is described below in the detailed description of Fig. 4 is described. The tape feed 44, which is provided with a plurality of circumferential belts or belts 72, which transport the respective plate by advancing the belts or belts 72.

In the preferred embodiment of the invention described below, according to which a foldable table 18 is provided on the medium supply and / or removal side, which has a foldable section 22 in its part closer to the print head arrangement 14.

In other words, such a table 18 also unfolds its advantages on any printing device which does not necessarily have to have the features of the main claim. The formation of a hinged table 18 on the medium supply and advantageously also on the media removal side causes the printing device is extremely flexible of roles on plate or sheet media convertible. In the folded-up state of the table 18, printing of roll media taken from the one roll, e.g. the medium roll 26, unwound and printed on another roll, e.g. the roll 52, to be wound up. In the folded state, the table 18 does not interfere with the operation. In this case, further advantages are obtained by the embodiment described, according to which the table 18 has a foldable section 22 in its region closer to the print head arrangement 14. This means that from the table 18 in its weg-, in particular folded-up state, a lower portion 22 can be folded away, so that the portion of the inkjet printing apparatus 10, in which the printing takes place, is readily accessible. Preferably, the hinged portion 22 of the folding table 18 is formed so that it can be folded away upwards, so that the access to the interior of the inkjet printing apparatus 10 is not appreciably hampered.

In such a table 18 is further preferred that this is provided with a plurality of rollers 20. Rollers 20 offer the handling of especially heavy plates to be printed, the advantage that they can be easily fed to the inkjet printing device 10, so that it can also be used for the printing of such media.

As previously mentioned, it is preferred for the hinged portion 22 of the table 18 to be hingedly attached to the body 12 at a location remote from the printhead assembly 14. This ensures that the hinged portion 22 can be effectively folded away from the printing device, so that access to this is affected as little as possible. In particular, the hinged portion 22 can be folded up on the folded-up table 18.

For the safe operation of the table 18 and the hinged portion 22, it also offers advantages when the table 18 and / or the hinged portion 22 is lockable in a working and / or a rest position. The working position of the tables 18 corresponds to the in Fig. 3 shown position, while the rest position of the tables 18 in the Fig. 1 and 2 is shown. As a result, there is the table 18 and the hinged portion 22 respectively in a defined secure position, it being noted that the table 18 and the hinged portion 22 may also be formed such that their position by stops and / or by its own weight, for example, when folding over a top dead center, results.

Since cardboard plates, unlike the preceding roller media, are not unwound from rolls, but are usually present as separate plates, the tables 18, which are preferably provided on both the feed side and the removal side, are expediently used. These are folded into their horizontal position and allow through the plurality of rollers 20 a smooth feeding of the plates to the inkjet printing device 10. As in Fig. 3 can be seen, the respective counter-pressure rollers 40, 42 and 48 of the associated feed 30, brake 38 and transport rollers 46 disengaged because the material transport in this case can be done exclusively by the tape feed 44. It should be noted, however, that in particularly heavy plates, the tape feed 44 may reach the limits of its performance, in other words too weak for further feed. In this case, the platen rollers 40, 42, and 48 engage the heavy plate material and cooperate with the associated rollers, such as the feed roller 30, the brake roller 38, or the transport roller 46, to move the material.

The predetermined by the tables 18 guide plane 138 for the medium 101 is arranged substantially in alignment with the plane of the guide surface 130 of the printing table 110. However, the guide plane 131 can also be slightly offset in height from the plane of the guide surface 130. However, it is also advantageous that the guide plane 131 in the direction opposite to the feed direction 137 has a course approximately corresponding to the bending line of the medium 101, since thereby in relation to the length of the medium 101 short guide surface 130 in the inkjet printing device 10th , a kinking of the stiff medium 101 is prevented.

In the top view of Fig. 4 the two tables 18 can be seen in their unfolded state. The tables 18 each have a plurality of rollers 20 which, in the case shown, are divided in three, as it were, along their axial extent, so that the individual sections of the rollers 20 are mounted on at least one side in one of the longitudinal struts 64. In the area of the respective table 18, which leads to the printhead arrangement 14 (FIG. Fig. 3 ) is closer, a hinged portion 22 can be seen, in one of the printhead assembly 14 ( Fig. 3 ) Far region is hingedly mounted on a folding axis 24. In the case shown, the folding movement of the hinged portion 22 is damped by a gas spring 70. It should be noted that the hinged portion 22 and / or the table 18 can be locked in total in one or both folding positions.

In Fig. 4 Furthermore, the tape feed 44 can be seen, which consists of several bands 72 or belt, in the case shown there are eight. The bands 72 extend in suitable grooves, to which, for example, by the slots 74 shown from the bottom a negative pressure is applied. Through the numerous openings 75 in the belts 72, the medium 101 is sucked in and transported by movement of the belts 72. In order to achieve a flatness of the medium 101, in particular during printing, suction openings 76 are also provided in the printing table 110 as such, which according to the invention can be operated independently of the openings 75 of the belts 72.

By the tape feed 44, which consists of a preferred embodiment of a plurality of circumferential bands 72, which are each provided with openings 75, the medium 101 is sucked and kept flat during printing. Between the belts 72 or belts are also located in the pressure table 110 suction openings 76 that support the Planhalten the medium 101. As mentioned above, the apertures 75 of the belts 72 and the suction ports 76 of the printing table 110 can be operated with different negative pressure so that a different suction force is applied to the medium 101 in different areas and flexible media do not bend in a manner which could affect the quality of the print results. In addition, during transport through the tape feed 44, the fixed suction openings 76 of the printing table 110 can be switched off, so that no unnecessary frictional force is applied to the transported medium 101 in this area, which would hinder the transport by the tape feed 44. To generate the corresponding negative pressure in the manner described, the openings 75 in the belts 72 and the suction ports 76 in the pressure table 110 are in communication with a vacuum system 77.

According to a preferred embodiment of the invention, as already mentioned, a feed device is provided which has at least one band 72 which is provided with openings 75 and to which a negative pressure can be applied. As a result, a tape feed 44 is formed, which is advantageous for certain media. The specific embodiment of such a tape feed 44 may for example be provided such that in the printing table 110 a comparatively flat and wide groove is formed, in which an endless belt is guided. The belt 72 has openings 75, and in the bottom of the groove, a connection to a vacuum system 77 is provided. Since the belt 72 can be sealingly abutted on its sides and on its edge, air is drawn in from the vacuum system 77 through the openings 75 of the belt 72, so that an impermeable medium 101 to be transported is sucked by the belt 72 and when moving of the belt 72 can be transported.

In this embodiment, a combination with a printing table 110 has proven to be particularly advantageous, which also has suction ports 76, which are, however, independently of the voltage applied to the tape feed 44 negative pressure supplied with negative pressure and adjustable in this regard. In other words, independently of each other, suction can take place through the movable openings 75 of the band 72 and the fixed suction openings 76 of the printing table 110. In this way, for example, when printing a particularly reliable Planhalten the medium to be printed 101 can be achieved by all the openings 75 and suction ports 76 are operated. However, by the time the medium 101 is to be transported, the fixed suction ports 76 of the printing table 110 may be turned off. As a result, the suction takes place only through the openings 75 of the band, i. of the belt 72, and this transport is not hindered by increased friction due to suction through the fixed suction ports 76. Finally, in experiments, applications have emerged in which certain media to keep them flat, are sucked by the fixed suction ports 76 weaker than by the movable openings 75 of the belt 72, as they bend otherwise unfavorable manner. By being able to independently operate and regulate the fixed and movable suction openings according to the described embodiment, special requirements in connection with certain media can be realized here. It should be noted that the above-described embodiment and the features thereof are an embodiment whose characteristics are also useful in a general ink-jet printing apparatus, which need not necessarily have the features of the main claim, and their advantages are exhibited.

In Fig. 5 Finally, a roller bearing for a medium roll 26, from which the medium 101 is unwound, shown in the ink jet printing device according to the invention 10 or may be seen separately from it.

In the case of the ink-jet printing device 10 according to the invention, preference is given to using a roller bearing which leads to smaller adaptations with respect to the edge of a roll medium and which, accordingly, can likewise be used independently of the other features according to the invention and taken as an object of the present application. This roller bearing is characterized in that it is adjustable in the axial direction 105, and that it is associated with a belt edge sensor 104. Conventionally, flexible media, which are not necessarily exactly straight wound, or in which the quality of the winding has deteriorated during transport, the edges are trimmed such that the resulting, trimmed edge is present at a defined location. This leads to a considerable amount of time and avoidable material loss. However, according to the invention, the edge of the roll media, i. of the medium 101 scanned continuously, and the axially adjustable roller bearing is tracked accordingly. In other words, in the event that it is detected that the edge of the roll media has moved slightly away from its desired position, the roller bearing is axially displaced such that the edge of the tape, i. the edge of the medium 101, again in the desired position. Since conventional roll media may have a diameter of up to about 30 cm, it is preferred for this that the tape edge sensor 104 has a corresponding depth of field so that it is unwound both in a situation in which the medium 101 is unwound from a nearly completely filled medium roll 26, as well as in a situation in which the medium 101 is unwound from a nearly empty medium roll 26, can securely detect the position of the edge of the medium 101.

As in Fig. 5 can be seen, the medium roll 26 on both sides of a bearing dome 78, which on one side, according to Fig. 5 the right side, with a comparatively narrow wheel, for example, with a V-shaped circumferential profile is provided. This narrow wheel engages in at least one provided with a suitable groove wheel 80 of the roller bearing. There is further provided a tape edge sensor 104 as part of a tape edge measuring device which always scans the position of the edge of the media 101 and generates a suitable signal when the edge of the media 101 has moved away from its desired position. In this case, the 105 adjustable roller bearing is adjusted in a suitable manner, so that the band edge is returned to its desired position. As a result, a medium 101 may be printed without trimming the edges as required by the prior art to bring them into the required position. For this purpose, the wheel is on the other side the medium roll 26 slidably mounted in the axial direction 105 in the roller bearing.

The Fig. 13 shows a detail of the roller bearing for the medium roll 26, according to Fig. 5 , in perspective. So that the edge of the medium 101 can always be held in a preselectable nominal position, a control loop is provided for this purpose, which consists of the strip edge sensor 104 of a strip edge control 106 and an actuator 107. If a deviation from the desired edge of the medium 101 is detected by the belt edge sensor 104, then a signal is generated due to this deviation in the belt edge control 106, causing the actuator 107 to return the position of the media roll 26 in the preselected desired position. The actuator 107 is designed so that it can move the roller bearing for the media roll 26 in the axial direction 105. The determination of the position of the band edge, ie the edge of the medium 101, can be carried out with the aid of various measuring principles. Particularly advantageous is an embodiment of the tape edge sensor 104 with a measuring system formed of light barriers.

In connection with the ink-jet printing device 10, there is further used a measuring and transporting system which is also independent of all the above-described features of the ink-jet printing apparatus 10 according to the invention and provides advantages in printing apparatuses not covered by the claims. The transport and measuring system is characterized in that both upstream and downstream of the printing table 110, a transport roller is present, each associated with a measuring device. And that is, as in Fig. 1 is shown, the brake drum 38, a measuring device 102 and the transport roller 46 is associated with a measuring device 103. In this way, the position of the material to be printed, ie the medium 101 both upstream and downstream of the printing table 110 and the print heads 16 can detect and control, resulting in the manner described below to very little waste. Usually, in a printing device, the front edge of a medium to be printed 101 must be advanced until a downstream of the printing table 110 lying transport roller 46 with an associated measuring device 103 detects the front edge and thus can bring the material in a defined position. In the described, novel measuring system, the positioning of the material or the front edge is first taken by the upstream, ie "before" the printing table 110 and the printheads 16 lying brake roller 38 and the transport roller 46 associated measuring system. In other words brings the upstream brake roller 38 by means of the associated measuring system, or the measuring device 102, the front edge of the medium 101 in a to Printing suitable position so that at the front edge of the medium 101 almost borderless, or with very little waste, can be started with the pressure. In the further course of the printing of the medium 101, the medium 101 is so long from the transport roller located upstream of the printing table 110, that is, the pushed forward until the front edge passes into the region of the transport roller 46 located downstream of the printing table 110. Earlier at this time, possibly also at a later time, the downstream transport roller 46 and the associated measuring system or the measuring device 103 takes over the transport and the regulation of the exact location of the medium 101. In particular, these components can take over the transport and the position control until the rear edge of the medium 101 reaches the area of the printing table 110 and thus can likewise be printed almost without borders. By means of a suitable control device 120, the signals of the two measuring devices 102, 103 are combined and adjusted with one another and, in particular, the "transfer" from the upstream system to the downstream system is undertaken.

The measurement of the feed distance can be done in a variety of ways. It is conceivable, for example, to attach marks to the medium to be printed 101 at a fixed distance from each other and to detect them by a suitable sensor. Furthermore, a specific pattern with recurring elements can be applied to the medium 101, so that on the basis of these recurring elements a detection of the feed distance can take place. Furthermore, this can be done using stochastic patterns, the z. B. be formed by the paper surface itself, carried out, wherein the detection takes place here together with a correlation measurement. In addition, the use of a measuring wheel or a measuring system with a drag clamp is possible. Advantageously, the measuring devices 102 and 103 for measuring the feed path of the medium 101 by the application of color marks on the medium 101, which are visible only under special electromagnetic radiation, are performed. For this it would be e.g. it is possible to apply only visible under UV light markers on the medium 101, which can be detected by corresponding, photoelectrically detecting measuring devices 102 and 103, respectively.

The Fig. 7 to 9 show in simplified representations means of the inkjet printing apparatus 10 for adjusting the distances of the printheads 16 and the printhead assembly 14 from the medium to be printed 101. For this, the inkjet printing apparatus is formed so that the printhead 16 and the printhead assembly 14, a distance sensor 111th is appropriate. This distance sensor 111 serves to measure a distance 112 between the top surface 113 of the medium 101 to be printed and an ink ejecting nozzle or nozzles 114 of the printhead assembly 14. Since both the printing table 110 and the printhead assembly 14 are liftable and lowerable, it is thus possible to use the ink jet To adapt printing device 10 very flexible and almost no additional conversion to different media to be printed 101. In particular, it is possible to print at least approximately plate-shaped media with a very different material thickness 115. The measured variable of the distance sensor 111 is used to regulate the distance 112 between the top 113 of the medium 101 and the nozzle or the nozzles 114 of the printhead assembly 14 at any time by means of a corresponding control device 120 to a required for proper operation setpoint 121 ,

Like in the Fig. 7 is shown, the printheads 16 and the printhead assembly 14 are mounted in a holder 122, wherein this holder 122 in a height guide track 123 of a carriage 124 vertically or vertically to the top 113 of the medium 101 of height can be adjusted. For this height adjustment of the holder 122, a lifting drive 125 which is controlled by the control device 120, actuated. The holder 122 for the print heads 16 is thus adjustable via the lifting drive 125 along the height guide track 123. The carriage 124 is in turn arranged on a transverse guideway 126 movable by an adjustment, so that the printhead assembly 14 can be moved laterally and parallel to the top 113 of the medium 101 on the top 113. The support 122, the carriage 124 and the transverse guideway 126 with the lifting drive 125 together form a support 127 for the printhead assembly 14. The support 127 is in turn arranged on a support guide 128 in the vertical direction movable on the machine frame 11 of the inkjet printing apparatus 10, wherein the vertical adjustment of the carrier 127 by a vertical adjusting device 129 which can be actuated by the control device 120 takes place. The carrier 127 of the printhead assembly 14 is thus adjustable via a vertical adjusting device 129 at least approximately perpendicular to a guide surface 130 for the medium 101. In the base body 12, the pressure table 110, which can be vertically adjusted via a height guide 135, is also arranged, wherein the latter is adjustable at least approximately perpendicular to the guide surface 130 of the medium 101 or relative to the print head arrangement 14 via actuators 136.

Fig. 8 shows a detail of the inkjet printing apparatus 10 in a sectional view, according to Fig. 7 , The medium 101 to be printed lies on the guide surface 130 of the printing table 110. The representation in Fig. 8 thus corresponds to a line of sight across the Feed direction 137 of the medium 101 and in the direction of movement of the carrier 127 and the printhead assembly 14 along the transverse guide path 126. The distance 112 between the nozzles 114 and the top 113 of the medium 101 can be changed in several ways. The height adjustment of the print head arrangements 114 is possible both by a vertical displacement of the holder 122 relative to the carriages 124 and by a vertical displacement of the carrier 127 on the carrier guide 128 fastened to the machine frame 11. Finally, it is also possible that the printing table 110 is moved by the actuator 136 in its height relative to the base body 12. In order to achieve the best possible result when printing on the medium 101, the outlet openings 138 of the nozzles 114 are arranged opposite one another in a plane 139 of the upper side 113 of the medium 101 or the guide surface 130 of the printing table 110, wherein the plane 139 and the upper side 113 of the medium 101 are aligned as parallel as possible.

The Fig. 9 shows a detail of the inkjet printing apparatus 10 with the carriage 124 shown in section. The print heads 16, in each of which a plurality of nozzles 114 are arranged, are in each case relative to the holder 122 by a Druckkopfhubantrieb 140 relatively adjustable. It can thus be achieved that, starting from a measurement of the respective individual distance 112 of each print head 16, the desired value 121 of the distance of the print head 16 from the upper side 113 of the medium 101 can be set. This is particularly advantageous if, as already described above, the feed devices ie the rollers described and / or the tape feed 44 are not sufficient to align the medium 101 on the guide surface 130 of the printing table 110 level. This may in particular be the case with intrinsically rigid media 101 such as cardboard plates, plastic plates or the like. Such a plate-shaped medium to be printed 101 may, for example, have a slight bend which can not be sufficiently reset by the sucking effect of the tape feed 101. Alternatively, it is also possible by the arrangement of at least two lifting drives 125 as in Fig. 9 indicated by dashed lines are the bracket 122 to tilt relative to the carriage 124 in which the two strokes indicated by dashed lines 125 are adjusted to different degrees. This ensures that the plane 139, which is determined by the outlet openings 138 of the nozzles 114, deflected from its relation to the guide surface 130 parallel position and thus on the other hand as parallel as possible to that portion of the top 113, which is directly opposite the nozzles 114 , In this way it can also be achieved that the individual distance 112 between the outlet openings 138 and the upper side 113 of the medium 101 can be tracked to the desired value 121 as far as possible.

The Fig. 10 shows a detail of the bracket 122 with a printhead 16 by multiple nozzles 114 are arranged. The individual nozzles 114 are each formed with a nozzle actuator 141, so that the distance 112 of the outlet opening 138 of each nozzle 114 can be additionally adjusted by the control device 120. This makes it possible for deviations of the upper side 113 of the medium 101 from the planar shape to set the distances 112 of the outlet openings 138 of the nozzles 114 more precisely. Preferably, the nozzle actuator 141 is formed by a micro-drive, for example a piezo drive. The trained by a micro-drive nozzle actuator 141 is formed so that the nozzle 114 against the action of an elastically recoverable restoring element such as a spring or an elastically recoverable plastic, for example, a polyurethane ring is adjustable. Of course, it is also possible that a plurality of nozzles 114 of a print head 16 is associated with a nozzle actuator 141, or a larger number of nozzles 114 are combined in a nozzle head 16 to nozzle groups and each of these nozzle groups is assigned a nozzle actuator 141.

The above-described means for changing the distance 112 between the outlet openings 138 of the nozzles 114 and the upper side 113 of the medium 101 to be printed together form an adjusting device wherein individual devices can be operated both manually and all together by the control device 120. Of course, it is possible that in an ink jet printing apparatus 10 according to the invention, the adjusting means only from a part of the devices, such as the actuator 136 for the printing table 110, the vertical adjustment device 129 for the carrier 127, the lifting drive 125 for the holder 122, the Druckkopfhubantrieb 140 is formed for the print heads 16 and the nozzle actuator 141 for the nozzles 114.

In order to determine the distance 112 between the upper side 113 of the medium 101 and the nozzle 114 or the nozzles of the printhead assembly 14 by the distance sensor 111, various known distance measuring methods can be used. For example, it is possible to measure the distance 112 by mechanically scanning the upper side 113 of the medium 101 to be printed. Particularly advantageous developments of the inkjet printing device 10, wherein the measurement of the distance 112 by means of acoustic, electrical or optical Distanzungsmeßmethoden is performed because there is no mechanical contact between the distance sensor 111 and the top 113 of the medium to be printed 101, thereby blurring the still wet ink or ink can be excluded. When using measuring methods such as light or general Using electromagnetic waves, the distance sensor 111 may be formed, for example, as a reflection light transmitter or as a rangefinder with an electro-optical receiving element.

For example, it is possible that an already applied color point is used for measuring the distance 112, in which a light beam is directed to this color point and the distance 112, between a nozzle 114 of the ink jet printing device 10 and the light reflected from this color point this facing top 113 of the medium 101 is determined.

In the embodiment of the inkjet printing apparatus 10 according to Fig. 7 the distance sensor 111 is formed at least in two parts and consists of a transmitting device 142 and a receiving device 143. The transmitting device 142 and the receiving device 143 are both attached to the print head assembly 14. In the case that the printheads 16 are arranged individually movable in the printhead assembly 14 as well as in the case that the nozzles 114 are in turn arranged individually movable in the printheads 16, the transmitting means 142 and the receiving means 143 are useful on the printheads 16th or attached to the nozzles 114. However, measuring methods for the distance sensor 111 are also conceivable in which one of the parts, ie the transmitting device 142 or the receiving device 143, is arranged on the print head arrangement 14 and / or on the print head 16 and / or on the nozzle 114 during the process Accordingly, other part, ie the receiving device 143 or the transmitting device 142, is arranged on the printing table 110.

The distance sensor 111 may also be attached to the side of the printhead assembly 14 or it is possible that on both sides of the printhead assembly 14, ie, respectively on both sides of the in or against the movement of the printhead assembly 14, along the transverse guideway 126 corresponding direction , are directed, in each case a distance sensor 111 is attached. Thus, the printheads 16 are each a distance sensor 111, in the feed direction, according to the direction of the transverse guideway 126, respectively, upstream, which offers the advantage that the local distance 112 can be recorded in a sense temporally anticipatory. On the other hand, it is also possible that the distance sensor 111 (in Fig. 8 shown in dashed lines) opposite to the feed direction 137 of the medium 101 upstream of the printhead assembly 14 is attached. In addition to the thereby possible, the actual printing time-anticipatory recording the distance 112 and thus the detection of the profile of the top 113 of the medium 101, this arrangement provides the distance sensor 111 also has the advantage that when feeding the medium 101, corresponding to the feed direction 137 of the distance sensor 111 can be used simultaneously for detecting a transversely to the feed direction 137 extending end edge of the medium 101. This makes it possible to prevent that when feeding a medium 101, the material thickness 115 is greater than the distance between the outlet opening 138, the nozzles 114 and the guide surface 130 of the table 110, the nozzles 114 of the printhead assembly are damaged. For this purpose, the control device (120) is designed to issue an error message, which takes place as soon as the sensor detects the upper side (113) of the medium (101) and the distance (112) does not correspond to the desired value (121), in particular is greater than the desired value ( 121).

As in Fig. 7 shown, the distance sensor 111 is attached to the printhead assembly 14. Of course, it is also possible for each of the printheads 16 has its own distance sensor 111 as in Fig. 9 shown on each nozzle 114 as in Fig. 10 arranged to arrange. This has the advantage that, in cooperation with the control device 120, an individual adaptation of the distance 112 for the nozzle heads 16 and also for the nozzles 114 is possible. Alternatively, it is also possible that a distance sensor 111 is arranged on the printing table 110.

The distance sensor 111 together with a transmission path and an evaluation unit or a Meßwertumsetzer a Distanzmeßvorrichtung. The evaluation unit or the measured value converter is preferably arranged in the control device 120. The distance sensor 111 and the distance measuring device are thus connected to the control device 120, which in turn is connected to the above-described elements of the adjusting device. By the distance measuring the actual value of the distance 112 is determined and compared in the control device 120 with a predetermined or adjustable setpoint value 121. The difference between the actual value of the distance 112 and the desired value 121 determined by the control device 120 then forms the basis for reducing this difference by driving the various elements of the adjusting device of the inkjet printing device 10. The inkjet printing device 10 is designed such that is detected by the distance measuring device, the actual value of the distance 112 continuously during the application of the ink with the printhead assembly 14 on the medium 101. For this purpose, furthermore, the control device 120 for reducing the difference between the setpoint value 121 and the actual value of the distance 112 during the application of the ink to the medium 101 is preferably constantly or even before the beginning of the application the color of the color with the printhead assembly 14 on the medium 101 activated.

For preselection or presetting of the setpoint value 121, setting devices are formed on the control device 120. Preferably, the control device 120 comprises an electronic computer, in particular a computer, wherein the specification of the desired value 121 can be made via a corresponding input keyboard of the computer. But it is also possible that this specification of the setpoint value 121 is carried out in the computer of the control device 120 program-controlled, to which other parameters which are essential for the printing process, such as e.g. the quality of the used inks or the surface condition of the medium 101 are automatically detected by the program or entered manually via the input keyboard of the computer.

With an ink-jet printing device 10 according to the invention, it is advantageously possible for the print head arrangement 14, in its relative position perpendicular to the plane of the support and / or guide surface 130, to have a distance 112 of 0.1 to 15 mm, preferably 0.5 to 10 mm, in a printing position for printing the medium 101 to position.

The Figures 11 and 12 show details of the arrangement of the platen roller 40 and the feed roller 30th

In Fig. 11 is a detail of the feed roller 30 and the platen roller 40, according to Fig. 3 represented. The medium 101 lies on the feed roller 30, wherein a situation is shown in which the medium 101 is slightly deformed, as may be the case, for example, in a self-rigid medium 101 such as a cardboard or plastic plate. In this case, a plurality of counter-pressure rollers 40 are formed, which are movably supported in a roller frame 144, relative to this roller frame 144, in the vertical direction. The roller frame 144 can be raised and lowered by the counter-pressure rollers 40 in a vertical direction, that is to say in a direction perpendicular to the guide surface 130. The counter-pressure rollers 40 can be brought by lowering the roller frame 144 to the upper side 113 of the medium 101, so that they rest on the upper side 113 and adapt to the slightly curved shape of this upper side 113 of the medium 101. The Fig. 12 shows a detail of the arrangement of the platen rollers 40 and the feed roller 30, according to Fig. 11 in a cutaway view. Each counter-pressure roller 40 is rotatably mounted on an arm 145 and is supported by a resiliently acting return element 146, such as a spring, against the roller frame 144. If now the roller frame 144 with the counter-pressure rollers 40 with a predefined force on the upper side 113 of the medium 101, the return elements 146 are compressed accordingly. From an achieved mean height of the roller frame 144, relative to the guide surface 130, it is possible to deduce the mean material thickness 115 of the medium 101. The determination of an average material thickness 115 is sufficiently exact for only slightly deformed media 101, on the basis of this value, the distance 112 (FIG. Fig. 7 ) with the aid of the control device 120 to the desired value 121 (FIG. Fig. 7 ) to adjust.

The in the Fig. 11 and 12 The arrangement described thus has the function of a distance measuring device, as it is also realized by the distance sensor 111 and can be used in combination with the distance measuring device 111 formed with a distance sensor as well as alternatively. Of course, it is also possible to use on the ink-jet printing apparatus 10, a separate arrangement of the feed roller 30 and the platen roller 40 of rollers, as a distance measuring device of the type described. Advantageous to the Distanzmeßvorrichtung, according to the Fig. 11 and 12 In particular, when feeding plate-shaped media 101 of greater material thickness 115, the media 101 can not be introduced into the printhead assembly 14 without the material thickness 115 being registered by a monitor and the printhead assembly 14 being moved vertically by the controller 120 and so the setpoint 121 can be specified. In particular, a corresponding monitoring device in cooperation with the control device 120 prevents the medium 101 from being fed into the area of the printhead assembly 14 in which printing can be erroneously initiated.

In the case of stiff, in particular intrinsically stiff, media which have a stiffness transversely to their feed direction 137, which permit lateral guidance or alignment in the lateral direction, it is advantageous if the medium 101, at least over part of the length of the guide surface 130 in the feed direction 137, a lateral guide track 150 is associated with the longitudinal side edge 151 of the medium 101. This lateral guideway 150 may be fixedly secured from a plurality of rollers 152 which are arranged at a distance from each other in the longitudinal direction of the medium 101 and which may be fastened fixedly on a housing part 153 which can be adjusted transversely to the direction of advance 137.

Preferably, these rollers 152 are made of a pressure-resistant material, so that the side guideway 150 represents an exact direction and side boundary for the medium 101. For certain intrinsically stiff media 101, it may prove advantageous to align them exactly on the side guideway 150 consecutively. For this purpose, it may prove advantageous to assign the opposing longitudinal side edge 154 of the medium 101 opposite the longitudinal side edge 151 to another side guide track 155. This may, in turn, consist of a plurality of rollers 152 arranged in alignment with one another, each individual roller 152 or groups of rollers 152 or the entire lateral guide track 155 transverse to the feed direction 137 against the action of means 165, for example springs, elastically biased in the direction of the opposite lateral guide track 150 , be stored adjustable. The rollers 157 of the side guideway 155 may also be dimensionally stable or hard, for example, formed by outer rings of ball bearings. But it is also possible to form the elastically biased means 156, characterized in that the rollers 157 are adjusted roughly adjustable on a housing part and the rollers 157 are elastic in itself, for example, from an elastically yieldable plastic or rubber material, such as polyurethane exist. Thus, it is possible that at low width variations of the medium to be printed 101 on the one hand, the reference edge of the medium 101 always abuts against the longitudinal side edge 151 backlash on the side leading edge 150 and width tolerances can be compensated by the deformation of the rollers 157 and the deformation of the spring. At the same time, a biasing force can be adjusted in the direction of the lateral guideway 150, with appropriate default, so that even at Maßunterschreitung the width of a safe investment of the reference edge of the medium 101 is ensured on the side guideway 150.

With the above-described ink-jet printing apparatus 10 of the present invention, it is possible to realize a method of printing different media by ink-jet printing in which the medium 101 is placed in the area of an ink-jet printing apparatus and from the digital data of a digitally stored image such as the position, intensity and / or color of a plurality of color dots, a reproduction of this image is produced by using the ink jet printing apparatus according to any one of claims 1 to 66, a substantially intrinsically rigid plate-shaped medium 101, optionally after detecting its Material thickness 115, relative to a planar bearing or guide surface 130 in the area of an ink jet printing device spent and then a plurality of arranged in a plane parallel to the upper surface 113 of the medium 101 plane 139 nozzles 114 transverse to the feed direction 137 of the M ediums 101 moves relative to this over the entire printing width and at the same time a plurality of lines of color dots in the feed direction 137th of the medium 101 are applied successively, whereupon the nozzles 114 are moved at least once again transversely to the feed direction 137 of the medium 101 relative to this over the entire printing width again a plurality of lines of color dots in the advancing direction 137 of the medium 101 in a row in the direction perpendicular to the surface of the medium 101 to the previously prepared color dots or the surface of the medium 101, or where the medium 101 is advanced by the number of lines made with the nozzles 114 in the feed direction 137, and that the medium 101 is alternately intermittently advanced or printed until the End of the image and / or the medium 101 is reached. It is preferred that before advancing the substantially inherently rigid, plate-shaped medium 101 on a flat bearing or guide surface 130 its material thickness 115 is checked and only when a match an actual value with the target value 121 of the advance of the medium 101 is released.

The substantially inherently rigid, plate-shaped medium 101 is also supported and / or guided at least over part of its length in the feed direction 137 before and optionally after the support or guide surface 130 in approximately the same plane by guide elements fixed relative to the medium 101.

With an ink-jet printing device 10 according to the invention, in particular a method for printing different media for digitally stored images can be realized. Based on the digital data of a digitally stored image, such as the position, intensity and / or color of an abundance of color dots, a reproduction of an image is made, an actual value of the distance 112 between the printhead assembly (s) 114 the inkjet printing device and a surface of the medium 101 and / or the guide surface 130 and / or the belt edge of the medium 101 facing the nozzles 114, and a presettable setpoint value 121 of the distance 112 and / or the position of the medium roll 26 transversely to the feed direction 137 of the medium 101 is specified relative to the base body. It is also advantageous that, at least before the start of the ink delivery, the ink jet printing apparatus reaches an actual value of the distance 112 between the printhead arrangement or the printheads or the nozzles 114 of the inkjet jet, which corresponds to the presettable setpoint value 121 of the distance 112. Printing device and a nozzle 114 facing surface of the medium 101 and / or the guide surface 130 is adjusted. Likewise, at least one of the inkjet printing device upstream and / or upstream counter-pressure roller and / or the distance measuring device at least before the supply of the medium 101 in the region of the printhead assembly to an actual value of the distance 112 between the printhead arrangement or the printheads or the nozzles 114 of the inkjet printing apparatus and a surface of the medium 101 and / or the guide surface 130 facing the nozzles 114, which corresponds to the presettable target value 121 of the distance 112 and it is determined whether the surface of the medium 101 is located at a distance 112 from the surface of the medium 101 facing the nozzles 114 and / or the guide surface 130, which deviates from the desired value 121.

To avoid material losses of the medium 101, it is particularly advantageous that the roller bearing for the medium roll 26 with the actuator 107 in the axial direction 105 is moved transversely to the feed device such that the band edge of the medium 101 in the printhead assembly in the setpoint is located and that the actual value of the band edge in the printhead arrangement or this is determined immediately upstream.

The quality of the images produced with an inkjet printing device according to the invention can be improved in particular by the distance 112 between at least one nozzle 114 of the inkjet printing device and the medium 101 and / or the position of the medium roll 26 continuously during the application of the color Printhead assembly is determined and that the difference between the setpoint and the actual value of the distance 112 and / or the position of the medium roll 26 is detected during the application of the color.

Due to the fact that the distance 112 in the direction of movement of the nozzles 114 of the print head and / or of the medium 101 is detected upstream of the nozzles 114 at a presettable distance, it is possible to pre-record profiles of the top side 113 of the medium 101 with a clear temporal advantage Control device 120 significantly reduce the requirements for their speed.

REFERENCE NUMBERS

10

Ink jet printer

11

machine frame

12

body

14

Printhead assembly

16

printhead

18

table

20

role

22

section

24

folding axis

26

medium roll

28

deflecting

30

feed roller

32

dancer roll

34

poor

36

sensor

38

braking roller

40

Backing roll

42

Backing roll

44

tape feed

46

transport roller

48

Backing roll

50

Backing roll

52

role

54

cutter

56

role

58

unloader

60

Ink absorbent pad

62

supporting edge

64

longitudinal struts

70

Gas spring

72

tape

74

Long hole

75

opening

76

suction opening

77

vacuum system

78

bearing mandrel

80

wheel

101

medium

102

measuring device

103

measuring device

104

Band edge sensor

105

direction

106

Edge control

107

actuator

110

printing table

111

distance sensor

112

distance

113

top

114

jet

115

material thickness

120

control device

121

setpoint

122

bracket

123

Vertical guideway

124

carriage

125

Linear actuator

126

Transverse guideway

127

carrier

128

carrier guide

129

adjustment

130

guide surface

131

management level

135

height Control

136

actuator

137

feed direction

138

outlet opening

139

level

140

Druckkopfhubantrieb

141

Nozzle actuator

142

transmitting device

143

receiver

144

roller frame

145

poor

146

Return element

150

Lateral guide track

151

Longitudinal side edge

152

role

153

housing part

154

Longitudinal side edge

155

Lateral guide track

156

medium

157

role

Claims (80)

1. Ink jet printing device for different media (101) with a print head unit (14) having at least one print head (16) for applying print to the medium (101) and a printing table (110) for positioning and/or guiding the medium (101) to be printed, an adjusting mechanism (125, 129, 136) for varying a distance (112) between the print head unit (14) and the medium (101) in a direction perpendicular to the guide surface (130) as well as a control system (120), and the printing table (110) being disposed on a machine frame (11) on which printing table a guide surface (130) for a medium (101) aligned in a plane is provided, and a feed system is provided on the printing table (110) to feed through a virtually inherently stiff medium (101), and the print head unit (14) can be displaced by means of a displacement drive along a transverse guide track (126) disposed on the machine frame (11) extending parallel with the plane and transversely to the feed direction (137) and incorporates several nozzles (114) for applying inks, the outlet orifices (138) of which are distributed in a same plane (139) parallel with the plane, characterized in that the ink jet printing device has a fold-down table (18) at the medium input end, which has a guide plane (131) for the medium (101), and the fold-down table (18) can be adjusted between an operating position and a non-operating position folded-up with respect to the operating position, and for applying print to the virtually inherently stiff medium (101), the guide plane (131) of the fold-down table (18) is in its operating position aligned substantially flush with the guide surface (130) of the printing table (110), and for applying print to a flexible medium (101), a medium roller (26) for the flexible medium (26) is disposed at the medium supply side and a roller (52, 56) for winding the printed medium (10) is disposed on the medium out-feed side, and the fold-down table (18) is preferably adjusted in the folded-up non-operating position.
2. Ink jet printer as claimed in claim 1, characterised in that the print head unit (14) can be positioned perpendicular to the plane of the guide surface (130), at least within a distance (112) of from 0.1 to at least 15mm, preferably 0.5 mm to 10mm, in a printing position for applying print to the medium (101).
3. Ink jet printer as claimed in claim 1 or 2, characterised in that an additional fold-down table (18) is disposed at the out-feed side, the guide plane (131) of the fold-down table (18) being aligned to be substantially flush with or slightly offset in height from the plane of the guide surface (130) of the printing table (110).
4. Ink jet printer as claimed in claim 3, characterised in that the guide plane (131) of the guide surface (130) has a contour more or less corresponding to the bending line of the medium (101) in the direction opposite the feed direction (137) thereof.
5. Ink jet printer as claimed in one or more of the preceding claims, characterised in that a monitoring system for the material thickness (115) of the medium (101) is arranged before the guide surface (130) in the feed direction (137) of the medium (101).
6. Ink jet printer as claimed in one or more of the preceding claims, characterised in that the medium (101) is guided at least along a part of the length of the guide surface (130) in feed direction (137) at the side, along a lateral guide track (150).
7. Ink jet printer as claimed in claim 6, characterised in that the lateral guide track (150) is provided in the form of dimensionally stable rollers (152) arranged at a distance one after the other in the feed direction (137).
8. Ink jet printer as claimed in one or more of the preceding claims, characterised in that both longitudinal sides of the medium (101) extending in the feed direction (137) co-operate with a lateral guide track (150, 155).
9. Ink jet printer as claimed in claim 8, characterised in that one of the two lateral guide tracks (150, 155) is displaceable transversely to the feed direction (137) against the action of means (157) elastically biassed in the direction of the oppositely lying guide track (150).
10. Ink jet printer as claimed in claim 8 or claim 9, characterised in that one of the two lateral guide tracks (150, 155) is provided in the form of rollers (152, 157) with a periphery which deforms in an elastically resilient arrangement.
11. Ink jet printer as claimed in one or more of the preceding claims, characterised in that several feed mechanisms for the medium (101) are provided, which can be activated, preferably separately from one another, opposite the printing table (110) on a preferably height-adjustable support (127) of the print head unit (14) and/or on the printing table (110).
12. Ink jet printer as claimed in claim 11, characterised in that the feed mechanisms are provided in the form of several separately drivable and controllable rolls for guiding the medium (101) to be printed lengthways, sideways and or in height (135).
13. Ink jet printer as claimed in claim 12, characterised in that the rolls are designed and disposed with a view to applying a feed force to the medium (101) to transmit a feeding motion in the feed direction (137) of the medium (101) to be printed.
14. Ink jet printer as claimed in claim 13, characterised in that at least one of the rolls co-operates with pressure rolls (40, 42, 48) which can be brought into and out of engagement.
15. Ink jet printer as claimed at least in one of the preceding claims, characterised in that a stationary guide mechanism, preferably a blocked roll, is provided, by and with which a material to be printed can be slidingly placed in abutment during printing.
16. Ink jet printer as claimed in claim 11, characterised in that one of the feed mechanisms is provided in the form of a belt feed (44).
17. Ink jet printer as claimed in claim 16, characterised in that at least the side of the belt (72) of the belt feed (44) directed towards the top face (113) medium (101) is provided with pores and/or orifices (75) to allow air through and these orifices (75) are connected to a vacuum system (77).
18. Ink jet printer as claimed in claim 16, characterised in that a belt (72) of the belt feed (44) has orifices (75) and a vacuum pressure can be applied to the belt.
19. Ink jet printer as claimed in one or more of the preceding claims, characterised in that suction orifices (76) communicating with a vacuum system (77) are provided in the guide surface (130) of the printing table (110).
20. Ink jet printer as claimed in claim 17 or 18, characterised in that the orifices (75) co-operate with the belt of the belt feed (44).
21. Ink jet printer as claimed in claim 19, characterised in that suction orifices (76) are provided in the guide surface (130) of the printing table (110) in the regions adjacent to the belt (72).
22. Ink jet printer as claimed in claim 21, characterised in that a respective independent, preferably different vacuum pressure, which can be individually switched off, can be applied at the suction orifices (76) of the printing table (110) and at the orifices (75) in the belt (72) and this vacuum pressure can be regulated.
23. Ink jet printer as claimed in one or more of the preceding claims, characterised in that a feed roll (30) is provided before a dancer roll (32) and co-operates with a measurement transmitter having a sensor (36) for detecting the distance of the dancer roll (32) perpendicular to the guide surface (130) of the medium (101).
24. Ink jet printer as claimed in one or more of the preceding claims, characterised in that a receiving device is provided in the region of the receiving surface of the printing table (110) for an ink absorbing unit which may be used and/or activated if necessary.
25. Ink jet printer as claimed in claim 24, characterised in that the ink absorbing unit has support edges (62).
26. Ink jet printer as claimed at least in one of the preceding claims, characterised in that it has a fold-down table (18), which has a fold-down section (22) in its part closer to the printer.
27. Ink jet printer as claimed in one or more of the preceding claims, characterised in that the table (18) is provided with a plurality of rollers (20).
28. Ink jet printer as claimed in claim 26, characterised in that the fold-down section (22) is mounted on the table (18) so that it can be folded down at a point farther away from the printers.
29. Ink jet printer as claimed in claim 26 or 28, characterised in that the table (18) and/or the fold-down portion (22) can be locked in an operating and/or a non-operating position.
30. Ink jet printer as claimed at least in one of the preceding claims, characterised in that a respective measuring device (102, 103) is provided both upstream and downstream of the printing table (110) or guide surface (130), preferably in the region of a conveyor roll (46) or a brake roll (38), for detecting longitudinal markers or front edges of the medium (101) extending transversely to the feed direction (137).
31. Ink jet printer as claimed in claim 30, characterised in that the measuring devices (102, 103) are disposed in the region of material supports.
32. Ink jet printer as claimed in one or more of the preceding claims, characterised in that a distance measuring device is arranged before the guide surface (130) in the feed direction (137) of the medium (101).
33. Ink jet printer as claimed in claim 32, characterised in that the displacement mechanism (125, 129, 136) can be controlled by the control system (120) in a direction perpendicular to the guide surface (130) at least before the medium (101) is introduced into the region of the print head unit (14) in order to reduce a difference between the desired value (121) pre-set in the control system (120) and an actual value of the distance (112), detected by the distance measuring device, between the top face (113) of the medium (101) to be printed and a nozzle (114) of the print head unit (14) ejecting ink.
34. Ink jet printer as claimed in claim 33, characterised in that a positioning drive (107) can be controlled by a belt edge control system (106), at least before the medium (101) is introduced into the region of the print head unit (14) in order to reduce a difference between the desired value for the position of the medium roller (26), which can be pre-set by the belt edge control system (106) and an actual value for this position detected by the strip edge sensor (104).
35. Ink jet printer as claimed in one of claims 32 to 34, characterised in that the distance measuring device has a sensor for scanning the top face (113) of the medium (101).
36. Ink jet printer as claimed in claim 35, characterised in that the control system (120) is set up to emit an error message if the sensor detects the top face (113) of the medium (101) and the distance (112) does not match a desired value (121), in particular if it is greater than the desired value (121).
37. Ink jet printer as claimed in claim 35 or 36, characterised in that the control system (120) is set up to emit an error message if the desired value (121) corresponds to the distance (112) and the sensor does not detect the top face (113) of the medium (101).
38. Ink jet printer as claimed in claim 33, characterised in that the actual value of the distance (112) may be continuously detected by the distance measuring device whilst ink is being applied to the medium (101) by the print head unit (14).
39. Ink jet printer as claimed in of claims 33 to 38, characterised in that the control system (120) is activated, preferably constantly, in order to reduce the difference between the desired and the actual value of the distance (112) whilst ink is being applied to the medium (101) by the print head unit (14).
40. Ink jet printer as claimed in one of claims 33 to 39, characterised in that the control system (120) is activated in order to reduce the difference between the desired and the actual value of the distance (112) before the print head unit (14) starts to apply ink to the medium (101).
41. Ink jet printer as claimed in one or more of the preceding claims, characterised in that the outlet orifices (138) of the nozzles (114) of the print head (16) of the print head unit (14) are disposed at the pre-settable distance (112) lying opposite the flat guide surface (130) for the preferably inherently stiff medium (101).
42. Ink jet printer as claimed in one or more of the preceding claims, characterised in that the guide surface (130) for the preferably inherently stiff medium (101) is disposed lying opposite the plane (139) and parallel thereto at a pre-settable distance (112).
43. Ink jet printer as claimed in one or more of the preceding claims, characterised in that the guide surface (130) is designed for flexible and inherently stiff media.
44. Ink jet printer as claimed in one of claims 33 to 40, characterised in that the distance measuring device has a distance sensor (111) disposed in the region of the print head unit (14) and/or on the printing table (110) and is connected to the control system (120) for detecting the actual value of the distance (112).
45. Ink jet printer as claimed in one of claims 33 to 40, characterised in that the distance measuring device has a distance sensor (111) disposed at least on a print head and/or on the printing table (110) and is connected to the control system (120) for detecting the actual value of the distance (112).
46. Ink jet printer as claimed in one of claims 32 to 40, characterised in that the distance measuring device has a distance sensor (111) disposed on one of the nozzles (114) of the print head (16) or adjacent thereto.
47. Ink jet printer as claimed in one of claims 44 to 46, characterised in that the distance sensor (111) for measuring the distance (112) is designed to operate by means of acoustic and/or electric waves, e.g. is an ultrasound sensor.
48. Ink jet printer as claimed in one of claims 44 to 47, characterised in that the distance sensor (111) for measuring the distance (112) is designed to operate by means of electromagnetic waves, e.g. is a reflected light sensor.
49. Ink jet printer as claimed in one of claims 44 to 48, characterised in that the distance sensor (111) for measuring the distance (112) is provided in the form of an optical or electro-mechanical distance sensor, optionally as a distance sensor with an electro-optical, digital or analogue receiver (143), e.g. a distance sensor having a CCD array.
50. Ink jet printer as claimed in one of claims 44 to 49, characterised in that the distance sensor (111) consists of several parts, e.g. a transmitter (142) and a receiver (143), and both parts are disposed on the print head unit (14) or on the print head or one of the nozzles (114).
51. Ink jet printer as claimed in claim 50, characterised in that one of the two parts of the distance sensor (111), e.g. the transmitter (142) or receiver (143), is disposed on the print head unit (14) or on the print head or on one of the nozzles (114), and the other part of the distance sensor (111), e.g. the receiver (143) or transmitter (142) of the distance sensor (111), is mounted on the print head or on one of the nozzles (114) or on the printing table (110).
52. Ink jet printer as claimed in claim 44 to 51, characterised in that the distance sensor (111) is disposed at a pre-settable distance before the nozzles (114) of the print head (16) in the feed direction (137) of the medium (101).
53. Ink jet printer as claimed in claim 33, characterised in that the control system (120) has setting elements for pre-selecting a desired value (121) for the distance (112).
54. Ink jet printer as claimed in one or more of the preceding claims, characterised in that the control system (120) comprises an electronic processor, in particular a computer.
55. Ink jet printer as claimed in claim 33, characterised in that the desired values (121) for the distance (112) can be pre-set via an input keyboard of the computer.
56. Ink jet printer as claimed in one of claims 11 to 14, characterised in that the support (127) of the print head unit (14) can be displaced substantially perpendicular to the guide surface (130) for the medium (101) or the printing table (110) by means of a vertical displacement mechanism (129).
57. Ink jet printer as claimed in one or more of the preceding claims, characterised in that the print heads (16) can be displaced relative to one another with respect to the print head unit (14) by means of a print head elevator drive (140) substantially perpendicular to a mount (122) of the print heads.
58. Ink jet printer as claimed in claim 57, characterised in that the mount (122) is displaceably mounted in a carriage (124) which can be moved in a transverse guide track (126) oriented so that it extends transversely to the longitudinal extension of the guide surface (130) and in a height guide track (123) disposed perpendicular to the transverse guide track (126).
59. Ink jet printer as claimed in claim 58, characterised in that the mount (122) for the print heads (16) can be displaced along the height guide track (123) by means of an elevator drive (125).
60. Ink jet printer as claimed in one or more of the preceding claims, characterised in that at least one nozzle (114) in the print head (16) can be displaced by a nozzle actuator (141) in a direction more or less perpendicular to the guide surface (130) for the medium (101).
61. Ink jet printer as claimed in claim 60, characterised in that the nozzle actuator (141) is a micro-drive, for example a piezo-drive.
62. Ink jet printer as claimed in claim 61, characterised in that the nozzle (114) can be displaced by the micro-drive against the action of an elastically rebounding return element, e.g. a spring or an elastically rebounding synthetic material, for example a polyurethane ring.
63. Ink jet printer as claimed in claim 60, characterised in that a nozzle actuator is assigned to several nozzles (114) in the print head (16).
64. Ink jet printer as claimed in one or more of the preceding claims, characterised in that the nozzles (114) are grouped in nozzle groups in a nozzle head and a nozzle actuator is provided for every nozzle group.
65. Ink jet printer as claimed in one or more of the preceding claims, characterised in that the printing table (110) can be displaced by means of positioning drives (136) substantially perpendicular to the guide surface (130) of the medium (101) and relative to the print head unit (14).
66. Ink jet printer as claimed in claim 66, characterised in that the printing table (110) displaceable by means of the positioning drives (136) is mounted so as to slide in a height guide (135).
67. Method of applying print to different media by ink jet printing, whereby the medium is introduced into the region of an ink jet printer, and on the basis of digital data of a digitally stored image, such as the position, intensity and/or a colour of a plurality of coloured dots, a reproduction of the image is produced by using an ink jet device as claimed in one of claims 1 to 66, whereby essentially inherently stiff board-type medium (101) is conveyed relative to a flat support or guide surface (130), into the region of an ink jet printer, and after which a plurality of nozzles (114) disposed in a plane extending parallel with the top face of the medium (101) is moved relative thereto, transversely to the feed direction (137) of the medium (101), across the entire printing width whilst a plurality of lines of coloured dots is simultaneously applied one after the other in the feed direction (137) of the medium (101), whereupon the nozzles (114) are then moved once again transversely to the feed direction (137) of the medium (101) and relative thereto across the entire printing width in order to apply another plurality of lines of coloured dots in the feed direction (137) of the medium (101) one after the other in a direction perpendicular to the surface of the medium (101) onto the previously made coloured dots, or whereupon the medium (101) is moved forwards in the feed direction (137) by the number of lines produced with the nozzles (114), and the medium (101) is intermittently fed forward or printed in alternation until reaching the end of the image and/or the medium (101).
68. Method as claimed in claim 67, characterised in that before the essentially inherently stiff board-type medium (101) is brought into the region of the ink jet printer, its material thickness is detected.
69. Method as claimed in claim 67 or 68, characterised in that before the essentially inherently stiff board-type medium (101) is moved forward onto a flat support or guide surface (130), its material thickness is checked and the forward feed of the medium (101) is not permitted unless an actual value matches the desired value.
70. Method as claimed in one of claims 67 to 69, characterised in that the essentially inherently stiff board-type medium (101) is supported and/or guided, at least across a part of its length, in the feed direction (137) before and optionally after the guide surface (130) in virtually the same plane by means of guide elements which are stationary relative to the medium (101).
71. Method as claimed in one of claims 67 to 70, characterised in that an actual value of the distance (112) between print heads of the ink jet printer and a top face of the medium (101) directed towards one of the nozzles (114) is detected, and a pre-settable desired value is set for the distance (112).
72. Method as claimed in claim 71, characterised in that the ink jet printer is adjusted, at least before the start of ink ejection, to an actual value for the distance (112) between print heads of the ink jet printer and a top face of the medium (101) directed towards the nozzles (114), which matches the pre-settable desired value of the distance (112).
73. Method as claimed in one of claims 71 to 72, characterised in that it is ascertained by a distance measuring device for detecting the actual value of the distance (112) between the print head unit of the ink jet device and the top face of the medium (101) directed towards the nozzles (114) whether the distance (112) deviates from the desired value.
74. Method as claimed in one of claims 67 to 73, characterised in that the roller mounting for the medium roller (26) with a positioning drive (107) is displaced in an axial direction transversely to the feed direction (137) so that the strip edge of the medium (101) is disposed so that it conforms to the desired value in the region of the print head unit.
75. Method as claimed in claim 74, characterised in that the actual value of the strip edge is detected in the region of the print head unit or immediately before it.
76. Method as claimed in claim 74, characterised in that the distance (112) between at least one nozzle (114) of the ink jet device and the medium (101) is detected continuously whilst the ink is being applied by means of the print head unit.
77. Method as claimed in one of claims 74 to 76, characterised in that the difference between the desired and the actual value of the position of the medium roller is detected whilst ink is being applied.
78. Method as claimed in one of claims 67 to 77, characterised in that the distance (112) is detected in the direction of displacement of the nozzles (114) of the print head and/or of the medium (101) before the nozzles (114) at a pre-settable distance.
79. Method as claimed in one of claims 67 to 78, characterised in that a marker, e.g. a coloured dot, is applied to the medium (101) and at least one light beam is than directed onto the marker or the coloured dot, and the distance between a nozzle (114) of the ink jet printer and the top face of the medium (101) directed towards it is detected on the basis of the light reflected by this coloured dot.
80. Method as claimed in one of claims 67 to 79, characterised in that in order to form a continuous hanging loop of the medium (101), the medium (101) is fed forwards in the direction of a guide surface (130) of the medium used to apply the ink until a distance perpendicular to the guide surface (130) of the medium (101) corresponds to a dimension of the subsequent intermittent forward feed motion of the medium (101) across the guide surface (130), whereupon the medium (101) is held stationary on the side of the loop remote from the guide surface (130) and is moved forwards, relative to the guide surface (130), in the longitudinal direction of the medium (101) by a pre-settable length of the distance of the loop.

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