EP1333985B1 - Printing device - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE A printing device is usable to print a material which is bent around a printing cylinder. The printing device includes a plurality of print heads and a print head holder. The print head holder positions the print heads in a common holder plane which is defined by the holder. The print heads are disposed in a row that is inclined relative to the printing device at an acute angle. The print heads are also inclined relative to the holder plane so that they are directed at substantially a right angle to the material to be printed.

Description

The present invention relates to a printing device for printing around one Printing cylinder curved print material, with a plurality of print heads and one Printhead holder for storing the printheads in one of the printhead holders defined holder level, the printheads along a to the printing direction in the pointed Angle inclined row are arranged along the print head holder.

"Print direction" means the direction of the print material relative to the print heads. Insofar as the printing material runs around the printing cylinder, the printing direction is perpendicular to Axis of rotation of the impression cylinder.

Ink jet printers usually work with two print heads, namely one for the Color and with one for black printing. Between the printed matter and the Printheads move in two axes. In the printing direction, the print material and the printheads are moved transversely to this, so that the pixels are separated by a temporal Control of the shooting times can be precisely aligned. It will usually printed on flat printed material, which causes positional deviations of the individual Pixels to their neighboring pixels are low and distortion of the printed image accordingly also occurs only slightly.

The disadvantage of these systems, however, is their limited printing speed and the Necessity of an exact control of the timing of the pressure nozzles in relation to to the axes of movement. The latter is complicated because the movement of the Print head is multi-axis relative to the print material.

To achieve high printing speed with a simple control, you can a variety of printheads can be arranged side by side to cover the entire To cover the width of the printed material. The movement between print material and print heads is uniaxial, there is only a movement of the printed matter in the printing direction. To one compact arrangement of the printheads and accordingly a high resolution reach, the individual printheads can be placed at an angle to the printing direction and in Printing direction offset from each other, so that the pressure points of the Complement the printheads and cover the entire width of the print material.

It is to enable easy assembly and arrangement of the printheads desirable, at least always two of the printheads on a common, level To attach the printhead holder. Here, however, it is difficult to distort the Avoid print image and achieve a high print quality, especially if is printed on curved printed material.

GB 23 49 607 A shows a printing device with a plurality of printing heads are arranged offset to each other. These printheads are related to one Printing cylinder arranged inclined in the radial direction.

The US 48 64 328 shows an ink jet print head with several rows of nozzles, which for Print direction are inclined.

EP1 033 254 A2 discloses a printing device with a plurality of printing heads, one Print head holder for storing the print heads in a position defined by the print head holder Holder level, with nozzle openings of the printheads along a to the printing direction in acute angle inclined row are arranged and wherein the holder plane to Printing direction is inclined at the acute angle.

The invention has for its object a printing device with compact To create arrangement and high print quality.

The object is achieved by the features of claim 1.

The advantages that can be achieved with the invention are, in particular, that the Printing device prints at high speed, achieves high print quality and Avoids distortion of the printed image. The printheads are relative to the holder level inclined in such a way that they spray essentially perpendicularly onto the printed material. Through the a flat printhead holder can be used and, at the same time, the print heads can be aligned essentially perpendicular to the corresponding ones Print target points. This avoids distortions of the printed image, it can excellent print quality can be achieved despite the highest printing speed.

The printheads can be relative to the holder level depending on their distance on the Printhead holder be inclined. In particular, the inclination is dependent on the Distance of the respective printhead from the center of the holder, being the center of the holder means the section of the print head holder that is closest to the print cylinder and which a straight line of diameter meets vertically through the impression cylinder. To that extent Printheads are arranged in pairs symmetrically to the center of the holder Distance of the printheads from the center of the holder half the distance of the printheads from each other, so the inclination depends on the distance of the printheads can be adjusted from each other.

In a further development of the invention, the print heads are in relative to the holder plane Dependence of the acute angle inclined, with which the printheads to the printing direction are inclined or with which the row of print heads to the printing direction extends. The slanted printheads in a row are on a common one Printhead holder attached so that the longitudinal direction of the printhead holder Alignment of the row corresponds and accordingly the inclination of the printheads relative to the printhead holder depending on the acute angle of the printhead holder is hit relative to the printing direction.

In order to achieve a simple adjustment of the print heads relative to the print head holder, the printheads are at two different angles in two perpendicular to each other Levels inclined. In particular, they can be in the holder level and in one level be inclined perpendicular to it. Regardless of the specific one to be set Inclination angles are the directions of the angles to be set, whereby the Specifications for the assembly must be given and carried out simply and precisely.

According to an advantageous embodiment of the invention, the print heads can by one first angle to be inclined in a plane which is connected by a straight line through the Print heads on the corresponding print head holder and the straight line connecting this intersecting diameter straight line is spanned by the pressure cylinder. The first Angle thus lies in a plane that contains the longitudinal direction of the print head holder and off an ellipse intersects the impression cylinder. The first angle is here for everyone Printhead selected such that the spray direction of the respective printhead is vertical on a tangent at a target point to the ellipse, from that plane is cut from the impression cylinder.

In a further development of the invention, the print heads are each relative to the holder level inclined a second angle in a plane that is perpendicular to the connecting straight line through the printheads, which are mounted on a printhead holder, and through the respective print head goes. The second angle is therefore in a plane perpendicular to Holder plane.

To print correspondingly wide print across its entire width without using the To be able to print printheads perpendicular to the printing direction are a number of Printhead holders arranged parallel to each other and each carry a plurality of inclined printheads. The inclination of the printheads becomes everyone Printhead holder set in the manner described above.

An embodiment of the invention is shown in the drawing and is in following described in more detail.

Fig. 1

eine Draufsicht auf eine Druckvorrichtung mit einem Druckzylinder, einem Druckkopfhalter und zwei darauf gelagerten Druckköpfen in einer schematischen Darstellung;

Fig. 2

einen Schnitt entlang der Linie B-B in Fig. 1;

Fig. 3

eine Seitenansicht der Druckvorrichtung in einer Blickrichtung parallel zur Längsrichtung des Druckkopfhalters;

Fig. 4

eine Frontansicht der Druckvorrichtung in einer Blickrichtung parallel zur Rotationsachse des Druckzylinders.

Show it:

Fig. 1

a plan view of a printing device with a printing cylinder, a print head holder and two print heads mounted thereon in a schematic representation;

Fig. 2

a section along the line BB in Fig. 1;

Fig. 3

a side view of the printing device in a viewing direction parallel to the longitudinal direction of the print head holder;

Fig. 4

a front view of the printing device in a viewing direction parallel to the axis of rotation of the printing cylinder.

The printing device 1 comprises a printing cylinder 2, which extends around its longitudinal axis 3 is rotatably mounted. The printing material runs around the printing cylinder 2, which corresponds to the Printing cylinder 2 is curved. Paper or the like can be provided as printed matter be so that the printing device 1 prints directly on the printed matter. The Printing device 1 can also be provided for printing plates for offset printing to illustrate. In this case, a printing plate is on the printing cylinder 2 as the printing material reared. With the printing device 1, the printing plate is first imaged and then to print with this.

As a printing unit, the printing device 1 has a multiplicity of printing heads 4 which follow work on the ink jet principle and in the form of a jet or small droplets spray the print material. For reasons of clarity, there are only two in the drawing Printheads 4 shown, which are attached to a common printhead holder 5. It however, it goes without saying that a multiplicity of print heads 4 transversely to the printing direction 6 provided next to each other and on adjacent print head holders 5 are attached so that the print areas of the individual print heads 4 complement each other and cover the entire width of the printed matter.

In the embodiment shown, there are two print heads 4 on the print head holder 5 arranged. The print head holder 5 is flat, it defines a holder plane B-B, in which all printheads 4 mounted on it are arranged. As shown in Fig. 1, the Printheads 4 tilted. They are at an acute angle γ to the printing direction 6 aligned to be closer together and for a higher resolution of the To achieve the printed image. According to the inclination of the print heads 4 extends the print head holder 5 with its longitudinal direction at the angle γ to the printing direction 6 in order to be able to store both printheads 4 (cf. FIG. 1).

The print heads 4 are arranged symmetrically to the center of the print head holder 5, d. H. they are equidistant from the holder center of the print head holder 5. The The center of the print head holder 5 is defined as the point of the print cylinder 2 is closest. This point is defined in turn by the fact that a radius R or a straight line of diameter of the printing cylinder 2 perpendicularly through the center of the holder the print head holder 5 is. As shown in Fig. 1, the print heads 4 are apart from each other Distance a spaced, accordingly the distance of the print heads 4 from Center of the holder each ½ a.

The print heads 4 are inclined relative to the print head holder 5, so that they with their Spray axis 7 is directed essentially perpendicularly to set points 8 of the pressure cylinder 2 and spray accordingly onto the print material. The print heads 4 are thereby relative to the print head holder 5 by two different angles which are in relation to one another vertical planes, inclined.

A first angle α, around which the print heads 4 are inclined relative to the print head holder 5, lies in the holder plane B-B, on the one hand due to the longitudinal direction of the printhead holder 5 or the connecting straight line 9 through the print heads 4 and the other through the Diameter straight through the pressure cylinder 2 is spanned by the Center of the printhead holder 5 goes and is perpendicular to this. The holder level B-B is the drawing sheet level in which Fig. 2 lies.

The holder plane B-B cuts from the impression cylinder 2 an ellipse 10, as shown in FIG. 2 can be seen since the holder plane B-B to the longitudinal axis 3 of the printing cylinder 2 around Angle γ or 90 ° -γ is inclined. The print heads 4 become relative to the print head holder 5 inclined by the angle α, so that they each point to the associated target point 8 on the Spray pressure cylinder 2. The angle α is dimensioned such that the respective Print head 4 with its spray axis 7 perpendicular to a tangent through the respective Target point 8 is directed. In section B-B according to FIG. 2, the tangent appears as Tangent to the ellipse 10 through the setpoint 8. The print head 4 is perpendicular to this directed.

The angle of inclination α in the holder plane BB relative to the print head holder 5 is determined as follows: α = arctan (cos (γ) tan (ψ)), in which ψ = arcsin (x i · Cos (γ)) / R in which x i = Rsin (ϕ) / cos (γ), in which ϕ = I 0 · (360 / 2Rπ), in which I 0 = a / 2cos (γ), With
a = distance of the print heads from each other, and
R = radius of the impression cylinder 2.

The inclination angle γ of the print heads 4 to the printing direction 6 is, for example 31 °. The radius of the impression cylinder 2 is, for example, 181 mm and the distance the print heads 4 on the print head holder 5 is, for example, 52.66 mm. In this In this case, the print head 4 is inclined by an angle α of 6.03 °.

In addition to the inclination by the angle α, each print head 4 becomes a second angle β relative to the print head holder 5 inclined to prevent distortion of the print image To prevent curvature of the printed image as far as possible. The angle β lies in a to Bracket level B-B vertical level. In particular, it stands at the holder level B-B vertical plane in which the angle β lies, perpendicular to the longitudinal direction of the Print head holder 5 or to the connecting straight line 9 through the print heads 4. The Reference point of β lies in the plane, the print head lies outside the plane, i. H. the shown angle β is distorted by the angle α. The plane of the angle β is the plane 3.

The angle β is determined in such a way that the respective printhead 4 is directed with its spray axis 7 essentially perpendicular to the tangent plane 11 to the printing cylinder 2 through the corresponding desired point 8. In particular, the angle of inclination β of the print head 4 is determined as follows: β = arcsin (sin (ϕ) · sin (γ)), in which ϕ = I 0 · (360 / 2Rπ), in which I 0 = a / 2cos (γ), With
a = distance of the print heads from each other, and
R = radius of the impression cylinder 2.

With the sizes given above for γ, R and a, the angle β is 3.61 °.

To the two inclination angles α; β are to be set between the Printheads 4 and the printhead holder 5 each incline adjusters switched, which can be integrated in the storage of the print heads 4 on the print head holder 5 can. The tilt adjustment devices not shown in the drawings are preferably biaxial, i.e. H. they can only be in the two levels, in which the angles α and β lie, are moved or set. Basically would be also ball head bearings and the like conceivable, with an inclination adjustment separate adjustment axes, however, has the advantage that the two inclination angles α; β are independently adjustable and accordingly the assembly or the adjustment is simplified.

In the described printing device 1 is only during the printing process the print material moves. The print heads 4 do not need to be moved transversely to the printing direction 6 to become. With the described printing device 1, the highest Print speed still an excellent and distortion-free print image to reach.

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

LIST OF REFERENCE NUMBERS

1

printing device

2

pressure cylinder

3

longitudinal axis

4

printhead

5

Print Head Holder

6

print direction

7

Spitz axis

8th

setpoint

9

connecting line

10

ellipse

11

tangent plane

a

distance

R

Radius (2)

B-B

Bracket level, cut

α

Angle, angle of inclination (B-B)

γ

Angle, skew angle

β

Angle, Tilt Angle (4)

Claims (11)

1. Printing device for printing curved printing material curved around a press cylinder (2), having a large number print heads (4), a print head holder (5) for mounting the print heads (4) in a holder plane (B-B) defined by the print head holder (5), nozzle openings of the print heads (4) being arranged in a row inclined at the acute angle (γ) with respect to their printing direction (6), and the holder plane (B-B) being inclined at the acute angle (γ) with respect to the printing direction (6), and a direction which is radial with respect to the axis of rotation (3) of the press cylinder (2) and which is arranged at right angles to the printing direction (6) lying in the holder plane (B-B), and the print heads (4) being arranged to be inclined relative to the holder plane (B-B) in such a way that they are aimed at the printing material substantially at right angles.
2. Printing device according to Claim 1, characterized in that the print heads (4) are inclined as a function of their spacing (a) on the print head holder (5).
3. Printing device according to one of the preceding claims, characterized in that the print heads (4) are inclined as a function of the acute angle (γ).
4. Printing device according to one of the preceding claims, characterized in that the print heads (4) are inclined at two angles (α; β) in two mutually perpendicular planes.
5. Printing device according to one of the preceding claims, characterized in that the print heads (4) are inclined in the holder plane (B-B) at an angle (α) with respect to a radial direction of the press cylinder (2).
6. Printing device according to the preceding claim, characterized in that the print heads are arranged in such a way that the angle (α) satisfies the following relationship: tan (α) = cos (γ) · tan (ψ), where ψ = arcsin (xi · cos (γ))/R, where xi = R · sin () / cos (γ), where  = I0 · (360/2Rπ), where I0 = a/2 · cos (γ), where
      a = spacing of the print heads (4) from one another, and
      R = radius of the press cylinder.
7. Printing device according to Claim 1, characterized in that the print heads (4) are in each case aligned at an angle (β) with respect to the holder plane (B-B).
8. Printing device according to Claim 7, characterized in that the print heads (4) are in each case inclined in such a way that the angle (β) satisfies the following relationship: β = arcsin (sin () · sin (γ)), where  = I0 · (360/2Rπ), where I0 = a/2 · cos (γ), where
      a = spacing of the print heads (4) from one another, and
      R = radius of the press cylinder.
9. Printing device according to one of the preceding claims, characterized in that a plurality of print head holders (5) are arranged parallel to one another and in each case carry a plurality of print heads (4).
10. Printing device according to Claim 1, characterized in that the printing device applies a means for changing the coating or a coating of a printing forme.
11. Printing device according to Claim 10, characterized in that the printing forme is constructed as a flat printing plate.

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