Patent Application
20090295895
The invention relates to an inkjet printer for printing different media, with a print head arrangement comprising at least one print head for printing the medium and a printing table forming a support plane for supporting the printing medium, and orifices of a suction system are provided in at least certain regions in the support plane for retaining the printing medium during the printing operation, as well as a forward feed mechanism for the printing medium.
In the cause of currently known inkjet printers, the printing medium is retained by suction through the orifices disposed in the support plane and the suction system communicating with it as a result. When printing sheet material of pre-definable sizes and applying the printed image by means of the inkjet print head arrangement, it is not always possible to prevent some warping of the printing medium in all applications.
The underlying objective of the invention is to provide a flat support for the printing medium in the support plane of the printing table.
This objective is achieved by the invention due to the fact that in the region of the printing table, at least one pressing mechanism with a pressing force acting in the vertical direction by reference to the support plane is provided for the printing medium, at least in the region of a side edge oriented in the forward feed direction.
The surprising advantage obtained as a result of the features defined in the characterizing part of claim 1 resides in the fact that, in addition to the retaining mechanism provided in the form of the suction system, the printing medium is also provided with at least one pressing mechanism in the region of its side edges oriented in the forward feed direction, because these peripheral regions are also disposed flush with respect to the support plane and can be pressed against it. During the printing operation, therefore, the distance between the print head and the surface of the printing medium is always kept the same. As a result, a perfect print quality is always obtained of the printed image to be applied to the printing medium, including in these peripheral regions, without distortions or even blurring of the printed image occurring during the printing operation. Due to the pressing force applied to the printing medium by the pressing mechanism, it is not just the central surface of the printing medium that is placed on the printing table and forward feed mechanism, even in the case of stiffer media to be printed, such as paper or card of a heavier sheet weight, and instead the suction system is assisted due to the presence of the additional pressing mechanism.
Also of advantage is another embodiment defined in claim 2 because the pressing mechanism can be adapted to different dimensions of the printing medium, in particular its width, relatively easily without the need for lengthy manipulations.
Another embodiment defined in claim 3 is also of advantage because it rapidly enables allowance to be made for different sizes or thicknesses of the printing medium, and the gap between the support plane, in particular the printing table or forward feed mechanism and the pressing mechanism, through which the printing medium must necessarily be fed can be adjusted quickly and further fine adjustments can still be made, including as the operation proceeds.
As a result of the embodiment defined in claim 4 or 5, it is possible to position the printing medium perfectly, precisely at both of its sides in the printing region of the print head arrangement whilst achieving a flat orientation by reference to the support plane in the region of the surface to be printed.
As a result of another embodiment defined in claim 6, a fixed disposition is obtained for the printing medium with respect to the printing table and print head arrangement relative to the base frame of the inkjet printer.
Also of advantage is another embodiment defined in claim 7 or 8 because uninterrupted operation of the print head arrangement is guaranteed in its printing region and the pressing mechanism is kept stable by means of the frame parts on the base frame of the inkjet printer. As a result, use is made of virtually the entire longitudinal extension of the pressing mechanism for applying the pressing force to the printing medium.
The advantage of the embodiment defined in claim 9 is that a reference edge is disposed or provided and is stationary with respect to the inkjet printer, in particular its printing table, and the other pressing mechanism can therefore be positioned on the frame parts associated with it transversely to the forward feed direction and thus adjusted depending on the width of the printing medium.
As a result of another embodiment defined in claim 10, a rapid adjustment can be made transversely to the forward feed direction and generally also a simple adjustment to cater for different widths of the printing medium.
As a result of the embodiments defined in claims 11 to 13, even before the printing medium is introduced, its width can be detected and the guide width of the pressing mechanism can be rapidly and automatically adjusted to the width of the respective the printing medium. It is also possible to check the medium as it is being fed along, in order to ascertain the printing width of the printed image to be applied.
Also of advantage is an embodiment defined in claim 14 or 15 because the printed image can be applied to the medium virtually up to its side edges, and only a minimal strip is left behind in the area covered by the pressing mechanism to which no printed image can be applied. This results in a high degree of economy whilst producing a perfect printed image.
In one embodiment defined in claim 16 or 17, the printing medium is advantageously prevented from becoming jammed between the pressing mechanism and the printing table or forward feed mechanism and the printing medium is also guided longitudinally as it is fed through the inkjet printer.
In this respect, an embodiment as defined in claim 18 has proved to be of advantage because it enables a stable disposition of the pressing mechanism to be obtained relative to the printing table and forward feed mechanism whilst nevertheless providing a reliable and flat support for the printing medium.
Also of advantage is an embodiment defined in claims 19 to 23. In this case, an additional option is provided for a guide section or stiffening section, by means of which different sizes or thicknesses of printing medium can be printed with the inkjet printer. In this respect, thicknesses of up to 1 cm and more are possible, such as needed when printing thick card or corrugated cardboard. The flat section of the pressing mechanism is also made stiffer, which means that the printing medium can be perfectly oriented and hence positioned on the support plane along virtually the entire longitudinal extension of the pressing mechanism.
As defined in claim 24, in spite of the flat section having a slim thickness or depth, additional stiffness is imparted to the flat section to prevent flexing in the direction perpendicular to the support plane and a virtually uniform pressing force is applied to the printing medium across the longitudinal extension of the flat section.
As a result of the embodiment defined in claim 25, an effective support is provided to enable the pressing mechanism to be changed rapidly on the one hand, and on the other hand, when the support element is retained accordingly on the flat section, a relative, mutual displacement of these two components is possible. The support elements may be supported by interconnecting a displacement mechanism, in particular one or more retaining elements.
As a result of another embodiment defined in claim 26, the printing medium is fed perfectly into the pressing mechanism. The printing medium is roughly oriented in the inlet region and then introduced into and positioned in the guide passage in which the pressing force is simultaneously applied to the medium by the pressing mechanism.
In this respect, another possible embodiment is defined in claim 27 and whilst the printing table remains stationary, the printing medium is able to effect a relative movement in the forward feed direction and the printing operation can proceed in steps in the printing regions or printing tracks disposed transversely to the forward feed direction.
Finally, yet another embodiment is defined in claim 28, whereby a flat support can also be provided for printing medium in the region of the printing table and printing is nevertheless able to take place across a bigger longitudinal range.
The invention will be explained in more detail below with reference to examples of embodiments illustrated in the appended drawings.
Of these:
Firstly, it should be pointed out that the same parts described in the different embodiments are denoted by the same reference numbers and the same component names and the disclosures made throughout the description can be transposed in terms of meaning to same parts bearing the same reference numbers or same component names. Furthermore, the positions chosen for the purposes of the description, such as top, bottom, side, etc., relate to the drawing specifically being described and can be transposed in terms of meaning to a new position when another position is being described. Individual features or combinations of features from the different embodiments illustrated and described may be construed as independent inventive solutions or solutions proposed by the invention in their own right.
As illustrated on a schematically simplified basis in
The print head arrangement 3 may be mounted or retained on a schematically illustrated frame part 10 of the inkjet printer 1, in a manner which has generally long been known from the prior art. A detailed description of this aspect will therefore not be given.
The inkjet printer 1 also has a printing table 11, which provides a flat support plane 12 for supporting the printing medium 2t. Orifices 13 of a suction system 14 also open into at least certain regions of the support plane 12, which are provided as a means of retaining the printing medium 2 during the printing operation. This operates by suction due to the differential pressure created.
In the embodiment illustrated as an example here, the forward feed mechanism 6 is provided in the form of at least one endlessly circulating conveyor belt 15. Irrespective of this, however, it would also be possible for the forward feed mechanism 6 to co-operate directly with the printing table 11 and move the medium 2 in the forward feed direction 7 past the print head arrangement 3 in a known manner together with the printing table during the printing operation.
If at least one or more conveyor belts 15 are used as the forward feed mechanism 6, appropriate orifices 13 or slots or similar are also provided in it or them, to enable the printing medium 2 to be sucked by the suction system 14 and hence onto the support plane 12. The lower pressure than the ambient atmospheric pressure may be generated by a schematically illustrated vacuum pump.
The suction system 14 described above in conjunction with the printing table 11 and optionally the conveyor belt 15 constituting the forward feed mechanism 6 ensure that the printing medium 2 delivered to the feed-in region 5 is sucked onto the forward feed mechanism 6 and printing table 11 and is thus held fixed during the printing operation to be carried out in the portion of the printing region 9 on the flat support plane 12 formed by the printing table 11 and forward feed mechanism 6.
As may be seen more clearly from
In order to adapt to different thicknesses of printing medium 2, the pressing mechanism 16 is designed and mounted so that it is able to move relative to the support plane 12 in a direction perpendicular to the support plane 12. The purpose of this movement is to provide a simple way of adapting or finely adjusting to differing thickness of the printing medium 2 quickly, in particular without involving extensive operations. Accordingly, this height adjustment relative to the support plane 12 may be carried out manually, for example by means of jack screws or similar, but may also be carried out automatically by means of displacement drives in conjunction with a control system of the inkjet printer 1, although this is not illustrated.
In order to adapt the pressing mechanism 16 or pressing mechanisms 16 to differing widths of the printing medium 2 transversely to the forward feed direction 7, at least one pressing mechanism 16 is provided in a direction perpendicular to the side edge of the medium 2 and parallel with the support plane 12, which is displaceable relative to the printing table 11. In this respect, it is preferable to provide a respective pressing mechanism 16 for each of the two side edges of the printing medium 2, which extends in the longitudinal direction, in other words in the forward feed direction 7, at least across the printing region 9 of the print head arrangement 3.
As briefly described above, the inkjet printer 1 has at least one frame part 10 respectively 17, which is illustrated on a simplified basis only, connected to a base frame or bed frame of the inkjet printer 1, which is merely indicated in the drawing and not shown by reference number. These frame parts 10, 17 are oriented transversely to, in particular perpendicular to, the forward feed direction 7. The print head arrangement 3 is retained or mounted on one of these frame parts 10, 17, and in the embodiment illustrated as an example here on the frame part 10, and can be displaced on it transversely to the forward feed direction 7 for performing the printing operation. The pressing mechanism 16 is also retained on at least one of these frame parts 10, 17 of the inkjet printer 1, and may optionally by mounted on it with interconnected retaining and displacement systems. However, the pressing mechanism 16 is preferably retained on one of the frame parts 10, 17 of the inkjet printer 1 disposed at a distance away in its longitudinal extension in the forward feed direction 7 and at a distance away in the direction perpendicular to the support plane 12. The two frame parts 10, 17 are therefore oriented transversely to, in particular perpendicular to, the forward feed direction 7 and, as viewed in the vertical direction, above the printing table 11, in particular the support plane 12, and are mounted on the base frame so as to be stationary, although they may also be displaceable if necessary.
In order to produce as long as possible a pressing area of the pressing mechanism 16, it is of advantage if the pressing mechanism 16 is mounted respectively at its ends 18, 19 spaced apart from one another in the forward feed direction 7 on a respective frame part 10, 17 of the inkjet printer 1 spaced apart in the forward feed direction 7 and oriented transversely to the forward feed direction 7, in particular perpendicular thereto, and at a distance from the support plane 12 in the vertical direction.
In the embodiment illustrated in
As may be seen more clearly from
The displacement mechanism 20, in particular the drive motor 25, may also be electrically connected to a schematically illustrated control unit 26. This being the case, it would be possible to pre-define a width of the printing medium 2 for the inkjet printer 1 via an input device, although this is not illustrated, and then move the displacement mechanism 20, in particular with the drive motor 25, via the control unit 26 so that the pressing mechanism 16 connected to the displacement mechanism 20 can be pre-set and adjusted to the width and hence the side edges of the printing medium 2. To enable the side edges of the printing medium 2 oriented in the forward feed direction 7 to be automatically detected, it would also be possible to provide at least one sensor in the feed-in region 5 of the printing table 11 oriented in the forward feed direction in order to detect a side edge the printing medium 2, in which case the sensor is electrically connected to the control unit 26. In order to retain clarity, a detailed illustration of the sensor has been omitted from the drawings. However, it might also be preferable to provide sensors for both of the side edges, by means of which the pressing mechanism 16 can be exactly oriented via the control unit 26, making allowance for the widths of the medium 2 as it is fed in.
When the medium 2 is being printed, the print head 4 of the inkjet printer 1 is guided along past the printing medium 2 at an exactly pre-definable distance from a printing plane on the medium 2. Since this distance between the printing plane of the printing medium 2 and the print head 4 is only relatively short, the pressing mechanism 16 may also extend by only a minimal degree across the printing plane formed by the printing medium 2 towards the side remote from the support plane 12. In the embodiment illustrated as an example, the pressing mechanism 16 is provided in the form of an essentially flat section 27 with flat faces 28, 29 and longitudinal side edges 30, 31 extending in between. The flat section 27 has an essentially rectangular cross-section, which has a width of 40 mm transversely to its longitudinal extension and a thickness of approximately 2 mm, for example.
In the region of the first longitudinal side edge 30, the flat section 27 has a pressing surface 32, offset from the flat face 29 directed towards the support plane 12, extending in the direction towards the oppositely lying flat face 28, which extends from the first longitudinal side edge 30 in the direction towards the other, oppositely lying longitudinal side edge 31. This pressing surface 32 may be offset from the flat face 29 directed towards the support plane 12 by an amount of 0.5 to 1 mm, for example. The pressing surface 32 extends from the first longitudinal side edge 30 across only a part-region of the width of the flat section 27 in the direction towards the other longitudinal side edge 31. This distance may be a quarter of the width of the flat section 27, for example.
Due to the fact that the pressing surface 32 is offset from the flat face 29 as described above, a transition region 33 is created between the pressing surface 32 and the face 29 of the flat section 27, which may also serve as an additional longitudinal guide portion 34 for the printing medium 2. In order to position the printing medium 2 exactly and provide a sufficient guiding effect for it in the forward feed direction 7 if necessary, the flat face 29 of the flat section 27 directed towards the support plane 12 is disposed directly adjacent to or adjoins it. The support plane 12 for the medium 2 may be formed either directly by the printing table 11 or the conveyor belt 15 of the forward feed mechanism 6.
On the longitudinal side edge 31 lying opposite the pressing surface 32, the flat section 27 may also have a web-type shoulder 35, the thickness 36 of which in the direction perpendicular to its longitudinal extension is slimmer than the thickness of the flat section 27 in the same spatial direction. The surface of the slimmer shoulder 35 is preferably flush with the flat face 29 directed towards the support plane 12. It would also be possible for the shoulder 35 to extend continuously along the longitudinal extension of the flat sections 27 or to be provided in certain regions only at pre-defined points.
This web-type shoulder 35 is used in situations where a thicker or deeper medium 2 has to be printed so that an additional angled section 37 can be held or placed on it, thereby imparting stiffness to the flat section 27 and also providing a longitudinal guiding action for the printing medium 2.
As may be seen more clearly from
Another leg 41 of the angled section 37 extends in the direction towards the support surface 12. Due to the slim thickness of the flat section 27 in the direction perpendicular to the support plane 12, it also has a lower section modulus, preventing flexing in this direction. It is therefore of advantage if the pressing mechanism 16 formed by the flat section 27 is mounted so that it is tensed in its longitudinal extension between the frame parts 10, 17 disposed at a distance apart in the forward feed direction 7. This tensing imparts an artificial stiffening effect to the flat section 27, which means that in spite of the slim thickness of the flat section 27, sufficient pressing force can be applied to the side edges of the printing medium 2 in the longitudinal direction, thereby resulting in a totally flat support on the support plane 12.
As may best be seen from
A comparison of
At least one stop element 45 is fixedly connected to the flat section 27 in the region of its end 19 and is in turn guided in the longitudinal direction of the flat section 27 in the support element 43 by means of a longitudinal guide to enable a relative displacement of the support element 43 with respect to the flat section 27 without the support element 43 being lifted off the flat section 27 in the direction perpendicular to its longitudinal extension. This guide may be provided by various different types of guide mechanisms known from the prior art, such as a dovetail guide, a T-groove guide or similar.
The stop element 45 is provided with a positioning element 46, which may be a bolt guided in the support element 43, for example. The stop element 45 is preferably oriented in the longitudinal direction of the flat section 27, in which case the positioning element 46 is oriented at an angle, in particular normal, to it. In a contact region of the stop element 45 and the positioning element 46, the latter are preferably provided with positioning surfaces 47, 48 extending at an angle with respect to their longitudinal extension, which engage with one another in the form of a slanting plane. When the positioning element 46 is moved in relative to the support element 32, for example by means of a lever arrangement 49—see FIG. 3—as indicated by the arrow in FIG. 6—a relative movement takes place between the support element 43 supported in a stationary arrangement on the frame parts 10, 17 and the flat section 27 connected via the stop element 45. The latter is tensed when the lever arrangement 49 is operated, for example in the form of a jaw closing movement, because the flat section 27 is moved relative to the support element 43 due to the mutually engaged positioning surfaces 47, 48 and the tensing force is thus applied to the flat section 27 of the pressing mechanism 16. If an angle that will produce a retaining action by friction is selected, an additional means for fixing the position in the tensed position can be dispensed with. It should be pointed out that the tensing mechanism for the flat section 27 illustrated here is but one of many examples of embodiments which might be selected. It would also be possible to use clamping elements of any other type, such as piston-cylinder systems, spindle drives, etc.
To enable the printing medium 2 to be fed in more easily and reliably and avoid any possible damage, it is also of advantage to provide a baffle mechanism 50 or one or more baffle elements on the pressing mechanism 16, in particular the flat section 27, at the end 18 facing the feed-in region 5, as indicated on a simplified basis in
The embodiments illustrated as examples represent possible design variants of the inkjet printer 1 and it should be pointed out at this stage that the invention is not specifically limited to the design variants specifically illustrated, and instead the individual design variants may be used in different combinations with one another and these possible variations lie within the reach of the person skilled in this technical field given the disclosed technical teaching. Accordingly, all conceivable design variants which can be obtained by combining individual details of the design variants described and illustrated are possible and fall within the scope of the invention.
For the sake of good order, finally, it should be pointed out that, in order to provide a clearer understanding of the structure of the inkjet printer 1, it and its constituent parts are illustrated to a certain extent out of scale and/or on an enlarged scale and/or on a reduced scale.
The objective underlying the independent inventive solutions may be found in the description.
Above all, the individual embodiments of the subject matter illustrated in
| Number | Date | Country | Kind |
|---|---|---|---|
| A 895/2005 | May 2005 | AT | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/AT2006/000213 | 5/24/2006 | WO | 00 | 7/31/2009 |
