EP1333984B1 - Printing device - Google Patents

Abstract

A printing device includes a plurality of print heads, each of which has a printing zone. An extension of this printing zone in a direction of printing defines a line height and an extension of this printing zone perpendicular to the direction of printing defines a column width. The printing heads are arranged in several parallel rows which are located at a distance from one another. The print heads in different rows are offset in relation to each other in a direction perpendicular to the direction of printing. A separation distance between the print heads in each row corresponds to the column width multiplied by the number of rows. The distance between the rows corresponds to the line height multiplied by the number of rows plus one.

Description

The invention relates to a printing device according to the preamble of claim 1.

The printing apparatus is provided with a plurality of printheads, each having a printing area whose extension defines a line height in printing direction and a width across the printing direction, wherein the printheads arranged in a plurality of spaced apart parallel rows and the printheads of different rows transversely to the printing direction offset from each other.

The term "printing direction" means the direction of movement of the print material to be printed relative to the printheads. If mounted on rotating printing plate cylinder printing plates are provided as print material, the printing direction is perpendicular to the axis of rotation of the printing plate cylinder.

Such printing devices are used, for example, to image offset printing plates. With the plurality of printheads, a coating agent or, conversely, a solvent for dissolving a coating of the printing plate can be sprayed thereon.

In order to obtain a high-quality printed image, it is desirable to be able to apply the medium to be applied to the printing plates via the printing device in every area of the printing plate in a finely and evenly distributed manner without any defects. For this purpose, the print heads are to be arranged sufficiently close together. On the other hand, the potential density of the printheads being stacked together is limited as they abut one another. In this respect, it would be desirable to manage with as few printheads.

The US 57 19 602 A shows an ink-jet printhead with a plurality of nozzle groups. These nozzle groups are arranged offset to one another.

The DE 37 30 844 A1 discloses a matrix ink printer in which a plurality of print heads, each with a plurality of nozzle openings are arranged offset from each other. In this case, the nozzle openings overlap based on the material to be printed.

The invention has for its object to provide a printing device.

This object is achieved by the features of claim 1.

The advantages achieved by the invention are in particular that the pitch of the printheads corresponds in each case a Druckkopfreihe the column width times the number of rows and the distance of the rows from each other of the row height times the increased by one number of rows. The column jumps in a print head row correspond to the number of print head rows, while the line jumps between adjacent print head rows are one greater than the number of print head rows of the printing apparatus. The printheads are arranged exactly so that there are no gaps and no overlaps between the printheads where printing would not be done twice. As a result, a high resolution can be achieved with a compact design of the printing device.

Advantageously, printheads of different rows are arranged in a common plane. In particular, one printhead from each row may each be in a common plane with a respective printhead from each other row. As a result, the assembly of the individual printheads is much easier. In particular, these may be mounted on a flat printhead holder. In addition to a compact arrangement, this makes it possible to achieve a simple adjustability of the print heads relative to each other.

In a further development of the invention, the individual print heads are arranged obliquely to the printing direction in order to achieve a higher resolution. Each print head has a longitudinal direction which is determined by its printing area or by the line along which the nozzle openings are arranged. The print heads are arranged obliquely to the printing direction so that said longitudinal direction extends at an acute angle to the printing direction. The angle can be adapted to the conditions, in particular to the design of the print heads. According to one embodiment of the invention, the angle between 20 ° and 45 °, in particular about 30 °.

In a further development of the invention, the print heads of different rows are inclined at the same angle. In particular, they may be arranged such that printheads of different rows lie with their longitudinal directions in a common plane. The common plane is inclined to the printing direction by the angle by which the printheads are tilted to the printing direction.

Embodiments of the invention are illustrated in the drawings and will be described in more detail below.

Fig. 1

eine schematische Darstellung der Anordnung der Druckköpfe einer Druckvorrichtung in zwei Reihen gemäß einer bevorzugten Ausführung der Erfindung;

Fig. 2

eine schematische Darstellung der Anordnung der Druckköpfe einer Druckvorrichtung in drei Reihen gemäß einer weiteren bevorzugten Ausführung der Erfindung.

Show it:

Fig. 1

a schematic representation of the arrangement of the print heads of a printing device in two rows according to a preferred embodiment of the invention;

Fig. 2

a schematic representation of the arrangement of the print heads of a printing device in three rows according to another preferred embodiment of the invention.

The printing device according to Fig. 1 includes 18 individual printheads 1 to 18 arranged in two printhead rows. The print head rows extend spaced apart from one another and parallel to each other, in each case perpendicular to the printing direction 19, which is indicated by the arrow.

All printheads 1 to 18 are each tilted at an inclination angle 20 to the printing direction 19 in order to achieve a higher resolution. Due to the inclination of the printheads 1 to 18, the printheads 1 to 18 can be arranged closer to each other in the direction of the print head rows and the distance between the nozzle openings of the individual printheads 1 to 18 can be reduced from one another transversely to the printing direction 19. As Fig. 1 The longitudinal direction of the print heads 1 to 18 is determined by the line along which the nozzle orifices of a printhead 1 to 18 are arranged. Due to the inclination, the nozzle row of each print head 1 to 18 is extended in the printing direction 19 and an extension transverse to the printing direction 19. The extent transverse to the printing direction 19 determines the column width of a print head 1 to 18, while the extension of the nozzle row in the printing direction 19, the line height the corresponding printhead 1 to 18 defined.

The printheads 1 to 18 in each print head row are spaced apart transversely to the printing direction 19. The pitch 21 of the printheads 1 to 18 of a printhead row corresponds to the column width times the number of printhead rows, in the embodiment shown according to Fig. 1 that is, the width of two columns: $$\mathrm{<figure-callout\; id="21"\; label="pitch"\; filenames="imgf0001.png"\; state="\{\{state\}\}">pitch</figure-callout>}21=\mathrm{column\; width}\times \mathrm{Number\; of\; print\; head\; rows}$$

The print head rows are also spaced from each other in the printing direction 19. Of the Row spacing 22 satisfies the following condition: $$\mathrm{<figure-callout\; id="22"\; label="Reihenbstand"\; filenames="imgf0001.png"\; state="\{\{state\}\}">Reihenbstand</figure-callout>}22=\mathrm{row\; height}\times (\mathrm{Number\; of\; print\; head\; rows}+1)$$

For two printhead rows, as shown in the embodiment shown Fig. 1 , The row spacing 22 thus corresponds to three times the line height, which is defined by the extension of the nozzle row of a print head 1 to 18 in the printing direction 19 as mentioned.

Corresponding to the selected arrangement of the print heads 1 to 18 is the transverse to the printing direction 19 each next print head 1; 2; 3; 4; 5; 6; 7; 8th; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18 always in the next row and is not arranged in the same printhead series. As the numbering of the printheads 1 to 18 shows, a first printhead 1 is arranged in the first printhead row while the subsequent second printhead 2 is arranged in the second printhead row.

In this printhead assembly can be advantageously provided that a plurality of printheads 1 to 18 are arranged in a common plane, so that they can be mounted on a flat holder. As Fig. 1 shows, the printheads 1 and 4, the printheads 3 and 6, etc. in a common plane and are each mounted on a common printhead holder 23 and 24 respectively.

This common plane of the nozzle openings of the print heads 1 and 4, 3 and 6, etc. is inclined to the printing direction 19 at the inclination angle 20 and is perpendicular to the printing plane, d. H. to the substrate. In the case of a rotating substrate, z. B. a printing plate of a rotating cylinder of a printing press, the plane is inclined to the axis of rotation of the cylinder and lies in the radial direction of the cylinder.

It is in principle possible, the at a print head holder 23; 24 mounted printheads 1 to 18 on different sides of the same to fix or to order. A simpler and therefore preferred arrangement is given by the fact that the mounted on a printhead holder 23 printheads 1 and 4 are arranged on the same side of the print head holder 23, as Fig. 1 shows.

The printhead holders 23; 24 may be mounted on a common carrier 25 ( Fig. 1 ).

The number of print head rows is preferably selected depending on the space required. According to Fig. 2 For example, printheads 1-18 can be arranged in three printhead rows. Otherwise, the arrangement of the printheads corresponds to 1 to 18 after Fig. 2 the arrangement according to Fig. 1 , In particular, the gap jumps between the printheads 1 to 18 correspond to a print head row and the line jumps, ie the row spacing in the printing direction 19 of the above-mentioned relationship. Likewise, the inclination of the individual printheads 1 to 18 corresponds to the context described above. For a further explanation of the embodiment according to Fig. 2 can therefore be waived.

This printing device carries a means for changing the coating (an additional coating can be applied, properties of a coating can be changed) of a printing form, in particular a planographic printing plate of a printing press.

LIST OF REFERENCE NUMBERS

1

printhead

2

printhead

3

printhead

4

printhead

5

printhead

6

printhead

7

printhead

8th

printhead

9

printhead

10

printhead

11

printhead

12

printhead

13

printhead

14

printhead

15

printhead

16

printhead

17

printhead

18

printhead

19

print direction

20

Inclination angle (1 to 18)

21

Pitch (1 to 18)

22

row spacing

23

Print Head Holder

24

Print Head Holder

25

carrier

Claims (7)

1. A printing apparatus with a plurality of print heads (1 to 18) which have in each case a printing area, the extension of which in the printing direction (19) fixes a line height and the extension of which transverse to the printing direction (19) fixes a gap width, wherein the print heads (1 to 18) are arranged in a plurality of parallel rows at a distance from one another and the print heads (1 to 18) of different rows are offset with respect to one another transversely to the printing direction (19), characterized in that the distribution interval (21) of the print heads (1 to 18) in one row in each case corresponds to the gap width multiplied by the number of the rows and the residual distance of the rows from one another corresponds to the line height multiplied by the number of the rows increased by one.
2. A printing apparatus according to the preceding Claim, characterized in that print heads (1 to 18) from different rows are arranged in a common plane, and in particular one print head (1; 3; 5; 7; 9; 11; 13; 15; 17) from each row is situated in a common plane in each case with a respective print head (2; 4; 6; 8; 10; 12; 14; 16; 18) from every other row.
3. A printing apparatus according to one of the preceding Claims, characterized in that each print head (1 to 18) has a longitudinal direction determined by its printing area, i.e. by the position of the nozzle openings, and is arranged with the said longitudinal direction at an angle to the printing direction (19).
4. A printing apparatus according to any one of the preceding Claims, characterized in that the print heads (1 to 18) are arranged in such a way that print heads (1 to 18) from different rows are situated with their longitudinal direction in a common plane.
5. A printing apparatus according to any one of the preceding Claims, characterized in that print-head holders (23; 24) are provided, on which print heads (1 to 18) from different rows are mounted, in particular at least one print head (1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18) from each row in each case, wherein the print-head holders (23; 24) are preferably made flat, and in particular have at least one flat surface.
6. A printing apparatus according to Claim 1, characterized in that the printing apparatus applies an agent for altering the coating or a coating of a printing forme.
7. A printing apparatus according to Claim 6, characterized in that the printing forme is constructed in the form of a flatbed printing plate.

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