DIGITAL PRINTING DEVICE COMPRISING A PRINT MEDIA ADVANCEMENT SYSTEM

Abstract

Digital printing device having a print media advancement system, and comprising: a sliding surface (3) of the print media, arranged at a printing area with above a printing module of the digital printing device; means for dragging (4) the print media, arranged downstream and/or upstream the printing area and arranged to make the print media advance in an advancement direction (x) above said sliding surface (3); wherein said sliding surface (3) comprises blowing portions (35) destined to realize an air cushion between sliding surface and print media (100). The sliding surface further comprises at least a suction portion (30), arranged to realise a depression by locally putting the print media near said sliding surface.

Claims

1. A digital printing device comprising a print media advancement system and a printing module, said print media advancement system comprising: a sliding surface of the print media, arranged at a printing area with above the printing module; means for dragging the print media, placed downstream and/or upstream the printing area and arranged to make the print media advance in an advancement direction above said sliding surface; said printing module being above said sliding surface; wherein said sliding surface comprises at least a blowing portion, arranged to realize an air cushion between said sliding surface and said print media, and at least a suction portion, arranged to realize a depression thus locally bringing the print media near said sliding surface.

2. The digital printing device according to claim 1, wherein said suction portions and said blowing portions are a plurality, alternated along the advancement direction.

3. The digital printing device according to claim 1, wherein said suction portions comprise first plates traversed by suction openings, at least a suction fan being arranged to realize a depression below said first plates.

4. The digital printing device according to claim 1, wherein said blowing portions comprise second plates below which blowing means are operating.

5. The digital printing device according to claim 4, wherein said second plates are realized in a porous material.

6. The digital printing device according to claim 1, wherein said sliding surface is a flat surface.

7. The digital printing device according to claim 1, wherein said suction portions comprise suction means and said blowing portions comprise blowing means, the suction means and the blowing means being independently adjustable from one another.

8. The digital printing device according to claim 1, wherein said means for dragging comprise a vacuum belt conveyor, arranged to bear the print media downstream said sliding surface and drag it according to the advancement direction.

9. The digital printing device according to claim 8, wherein said vacuum belt conveyor is realized in the form of a perforated belt wound up between two rollers, suction means being arranged below said perforated belt.

10. The digital printing device according to claim 8, wherein said means for dragging further comprise a pair of nip rolls arranged upstream said sliding surface to drag the print media in the advancement direction, a first motor for the activation of said nip rolls and a second motor for the activation of said belt vacuum being synchronized with one another.

11. The digital printing device according to claim 8, wherein said vacuum belt conveyor is mounted on a sled transversally mobile with respect to the advancement direction for controlling the transversal position of the print media with respect to the printing module of the printing device.

12. The digital printing device according to claim 11, further comprising a sensor to acquire a transversal position of the print media on the sled and a linear actuator for the transversal positioning of the sled activated on the basis of the reading of said sensor.

13. The digital printing device according to claim 1, wherein said print media is a print media that can be reeled, for example paper or plastic, said means for dragging comprising at least an unwinding roller arranged upstream the sliding surface and a winding roller arranged downstream the sliding surface.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0037] FIG. 1 shows a general scheme of a print media advancement system according to the present invention;

[0038] FIG. 2 shows a perspective view of two prominent elements, a sliding bed defining a sliding surface and a vacuum belt conveyor, of the advancement system of figure.

[0039] FIG. 3 shows a transversal section of the sliding bed of FIG. 2.

MODES FOR CARRYING OUT THE INVENTION

[0040] With reference to the annexed FIG. 1, we generically identify with 1 a print media advancement system for digital printing device according to the present invention.

[0041] We note that such advancement system 1 is generally integrated in a digital printing device, namely in a device arranged for the digital printing of a print media.

[0042] Such printing device, known per se, preferably comprises a fixed bridge under which the print media is dragged, which can be of any nature. One or more print heads, mounted on a printing module 200, provide for the delivery of ink on the print media that transits under them, realizing an image, a motif, a decoration, or any graphic element desired.

[0043] The advancement system 1, arranged in particular to move a paper or plastic film media, provides for an upstream unwinding roller 20 for the supply of the print media 100.

[0044] The print media 100, in a manner known per se, coming out from the unwinding roller 20 winds on a pair of rewind assist rollers 21, therefore on a compensator roller 22, to be then taken by a pair of nip rolls 23, one of which is motorized.

[0045] At this point, in the device of the present invention the print media 100 moves, along an advancement direction x, on a sliding surface 3 corresponding to a printing area 10. In this area, in fact, the printing module 200 of the digital printing device is above the media 100, delivering the quantity of ink necessary for the realization of the desired graphic element.

[0046] At the exit of the printing area 10 the print media 100 is born by a vacuum belt conveyor 40, followed by a stretching roller 44, a last rewind assist roller 45, last, a winding roller 46.

[0047] The electric motor 41 that activates the vacuum belt 40 is synchronized to the one that moves the nip rolls 23, so as to guarantee a homogeneous advancement of the whole print media 100.

[0048] In particular, the combined action of the nip rolls 23 and of the vacuum belt 40 defines a homogeneous tension of the print media among such organs, namely along the whole printing area 10.

[0049] The sliding surface 3, in this particular case flat, is defined by the superior surface of a bed represented in a detailed manner in FIGS. 2 and 3.

[0050] The sliding surface 3 exhibits suction portions 30 alternated with blowing portions 35.

[0051] The suction portions 30 are defined superiorly by first plates 31, preferably of steel, which close transversal depression chambers 38 realized in the bed. The depression chambers 38 are kept in depression by means of one or more suction fans 33, arranged at an inferior outlet. The first plates 31 provide for suction openings 32, in particular cracks, which put in communication the depression chamber 38 and the above sliding surface 3.

[0052] The suction portions 30 suck up the print media 100, thus locally bringing it near the sliding surface 3 but without making the media adhere to the surface.

[0053] The blowing portions 35 are defined superiorly by second plates 36, preferably of porous aluminum, which close transversal pressurized chambers 34 realized between a depression chamber 38 and the other one. The pressurized chambers 38 receive compressed air from an underlying compressed air circuit 37.

[0054] The air passes through the second porous plate and realizes a fluid bed that lifts and stretches the print media 100 between two subsequent suction portions 30.

[0055] Thus, the alternation of suction portions 30 and blowing portions 35 advantageously allows to locally stretch the print media, in particular at the print heads that rest on the blowing portions 35.

[0056] Different power adjustments for suction and blowing allow to adapt the sliding bed to different print media 100.

[0057] The vacuum belt conveyor 40 is mounted on a sled 42, mobile in transversal direction with respect to the advancement direction x as a result of a linear actuator 43. A fork-shaped sensor, mounted on the opposite side with respect to the linear actuator 43 and not represented in the annexed figures, allows the reading of the linear position of the print media 100 and eventually corrections in case of missing alignment with respect to the printing module 200.

[0058] Naturally, to the description made here, in order to satisfy contingent and specific needs, a skilled person will be able to devise further modifications and variants, all however contained in the scope of protection of the invention as defined by the following claims.