Printing system comprising an adjustment actuator for the adjustment of a plurality of print heads

Abstract

A printing system with at least one printing bar which comprises at least a first and a second print head, wherein the printing system is designed in such a way that the first and the second print head can be adjusted in an actuator-based manner in relation to a print medium by positioning and orienting by means of a single adjustment actuator, wherein an auxiliary means with the single adjustment actuator is arranged on the printing bar in such a way that, with the help of this auxiliary means, an operative connection of the adjustment actuator to the first print head can be released and / or established and an operative connection to the second print head can be released and / or established, characterized in that the adjustment actuator comprises: - only one motor, a first screw head which is mounted rotatably about a first axis, a second screw head which is mounted rotatably about a second axis, a drive train which is drive-connected to the motor and the first and second screw head in such a way that a rotational movement of the motor is turned into a simultaneous rotational movement of the first screw head about the first axis and of the second screw head about the second axis.

Description

[0001] Printing system with adjustment actuator for adjusting multiple print heads

[0002] The present invention relates to a printing system with an adjustment actuator for adjusting multiple print heads.

[0003] Today, a wide variety of printing systems with print heads can print on a wide variety of media, such as paper or corrugated cardboard. The print heads are positioned either fixed or scannable relative to the print medium. In any case, the printing system must be configured during initial commissioning, and correct alignment of the print heads with respect to the print medium through orientation and positioning is of utmost importance. If only individual defective print heads need to be replaced in an already aligned system, then generally only the newly installed print heads in the printing system require alignment.

[0004] At this point, some of the terms used in this description should be defined.

[0005] A printing system is a device with which a printing medium can be printed with printing material according to a predetermined pattern.

[0006] When reference is made to a print head in this description, this refers to a component with one or more nozzles arranged in one or more rows through which the printing material can be precisely positioned and directed toward the printing medium. An array of nozzles belongs to one and the same print head if the printing system's application allows the array to be positioned and oriented only as a whole. "In the application" here means that the print head is assembled and installed in the printing system.

[0007] An actuator is a general term for a component that converts electrical signals into mechanical movement or other physical quantities. Actuators, as defined in the present invention, convert electrical signals into mechanical movement.

[0008] When an adjustment actuator is referred to in this description, this means an actuator with the aid of which a first object (here the print head), with which it is operatively connected, can be mechanically moved in terms of positioning and orientation relative to a second object (here, for example, the printing medium to be printed and / or the adjacent print head).

[0009] Positioning is understood as the movement of the first object into a desired position relative to the second object. Orientation is understood as the rotation of the first object into a desired orientation relative to the second object.

[0010] When reference is made to a spur gear in this description, it means a cylindrical wheel or a cylindrical disc that has teeth on its circumference.

[0011] WO 2022 028733 A2 discloses a printing system with a print bar comprising at least a first and a second print head, wherein an auxiliary device is provided in the printing system such that with the aid of said auxiliary device an operative connection of a first adjustment actuator to the first print head can be released and / or created and an operative connection of a second adjustment actuator to the second print head can be released and / or created one after the other, wherein each adjustment actuator comprises a motor.

[0012] The device disclosed in the generic US2019255867A1 is designed solely for the adjustment of a plurality of print heads on a single print bar, and comprises a plurality of motors mounted for joint movement, which are arranged in a row on a rail attached to the print bar and displaceable relative to the print bar, which row extends orthogonally to a transport direction of a printing material, wherein the device is designed such that a temporally parallel adjustment of a plurality of print heads on the print bar is possible by means of the plurality of motors.

[0013] Previously known printhead alignment devices allow for relatively short setup times for aligning printheads on a single print bar. However, they are relatively heavy and expensive to purchase and maintain.

[0014] The present invention is therefore based on the object of providing a printing system with a simple device for adjusting multiple print heads of a single print bar, which allows for a relatively short setup time, but is lightweight and, at the same time, cost-effective to manufacture. According to the invention, this object is achieved with a printing system comprising the features of claim 1. The subclaims relate to further advantageous and, where appropriate, additionally inventive embodiments.

[0015] The printing system according to the present invention is a printing system with at least one print bar, which comprises at least a first and a second print head, wherein the printing system is designed such that the first and second print heads can be adjusted in an actuator-based manner with respect to a print medium by positioning and orientation by means of a single adjustment actuator, wherein an auxiliary device with the single adjustment actuator is arranged on the print bar, such that with the aid of which an operative connection of the adjustment actuator with the first print head can be released or created and / or an operative connection with the second print head can be released or created.

[0016] According to the invention, the adjustment actuator comprises: only one motor, a first screw head rotatably mounted about a first axis, a second screw head rotatably mounted about a second axis, a drive train which is drive-connected to the motor and the first and second screw heads in such a way that a rotational movement of the motor is translated into a simultaneous rotational movement of the first screw head about the first axis and of the second screw head about the second axis.

[0017] By eliminating the need for multiple motors to adjust the print heads of a single print bar, weight and, in particular, costs of the auxiliary equipment can be saved.

[0018] According to a preferred embodiment, the drive train comprises a gear drive configured as a belt drive or as a belt and gear drive. This preferred development offers the advantage of allowing the implementation of an adjustment device of sophisticated and cost-effective design.

[0019] According to a further preferred embodiment, the wheel drive comprises: a first spur gear, which is axially and rotationally connected to the first screw head via a first output shaft rotatable about the first axis; a second spur gear, which is axially and rotationally connected to the second screw head via a second output shaft rotatable about the second axis; a motor spur gear, which is axially and rotationally connected to a motor shaft of the motor;

[0020] - wherein the motor spur gear is drive-connected to the first and second spur gears via a toothed belt.

[0021] This preferred further development offers the advantage that an adjustment device of very simple and lightweight design can be realized.

[0022] Furthermore, according to a first preferred variant, it is possible for the motor spur gear to be directly drive-connected to the first and second spur gears via the toothed belt.

[0023] Furthermore, in an alternative preferred second variant, it is possible for the motor spur gear to be indirectly drive-connected to the first and second spur gears via the toothed belt, wherein the first spur gear is rotatably engaged with a first counter-spur gear which is rotatable about an axis and is axially connected to an additional first spur gear via a shaft, and the second spur gear is rotatably engaged with a second counter-spur gear which is rotatable about an axis and is axially connected to an additional second spur gear via a shaft, and wherein the motor spur gear is directly drive-connected to the additional first and second spur gears via the toothed belt.

[0024] The axes of rotation around which the spur gears, which are directly connected to the drive via the toothed belt, are rotatably mounted are preferably arranged relative to one another in such a way that they form the vertices of a notional triangle, in particular an isosceles triangle. This preferred development offers the advantage of increasing the reliability of the drive of the first and second screw heads.

[0025] According to a preferred embodiment, the first output shaft is displaceable along the first axis by means of a first hydraulically or pneumatically and / or electrically operating actuator between an extended position, in which the first output shaft is operatively connected to the first print head, and a retracted position, in which the first output shaft is not operatively connected to the first print head. The second output shaft is displaceable along the second axis by means of a second hydraulically or pneumatically and / or electrically operating actuator between an extended position, in which the second output shaft is operatively connected to the second print head, and a retracted position, in which the second output shaft is not operatively connected to the second print head. This allows a secure and simple mechanical connection to be created or released between the motor of the adjustment actuator and the first and / or second print head.

[0026] According to a further preferred embodiment, the motor is a stepper motor.

[0027] Furthermore, it is possible for the auxiliary device to comprise at least one linear guide and a carriage, wherein the carriage is arranged displaceably on the linear guide and the adjustment actuator is attached to the carriage, wherein the auxiliary device is mounted on and above the pressure beam.

[0028] According to a particularly preferred embodiment, the print bar comprises two print head rows aligned parallel to one another, wherein the first print head row comprises the first print head and the second print head row comprises the second print head, and wherein the first and second screw heads are arranged in such a way that with the aid of the auxiliary device, an operative connection of the adjustment actuator via the first screw head to the respective print heads of the first print head row can be successively released or created and / or an operative connection via the second screw head to the respective print heads of the first print head row can be successively released or created.

[0029] Furthermore, it is possible for the printing system to comprise a printing roller which is rotatable about an axis and has a cylindrical roller shell which is designed to receive the printing medium and to rotate it in a direction of rotation, wherein the printing beam is assigned to the roller shell at a distance, and wherein the first axis of the first output shaft and the second axis of the second output shaft are aligned in a V-shape with respect to the printing roller, preferably with respect to the axis of rotation of the printing roller.

[0030] In this case, the first spur gear and the counter-spur gear rotatably engaged with the first spur gear are particularly preferably designed as a first bevel-spur gear pair, and the second spur gear and the counter-spur gear rotatably engaged with the second spur gear are designed as a second bevel-spur gear pair, wherein preferably one bevel-spur gear of a bevel-spur gear pair is rotated relative to the other bevel-spur gear of the bevel-spur gear pair. According to a further preferred embodiment of the printing system according to the invention, an optical means is provided in the printing system such that it enables automatic adjustment of the print heads, preferably via predetermined printed test patterns, wherein the optical means and the auxiliary device are designed to cooperate.This training is advantageous because, on the one hand, the maintenance effort for adjusting the print heads can be minimized and, on the other hand, the corresponding adjustment can even be carried out by a layperson without specialist knowledge.

[0031] The printing system can be an inkjet printing system.

[0032] The invention will now be explained below by way of example and with reference to the figures.

[0033] Figure 1a shows a schematic plan view of a particularly preferred embodiment of the printing system according to the invention with auxiliary device.

[0034] Figure 1b shows a schematic front view of the second section of the printing system from Figure 1a in cross section.

[0035] The general principle of adjusting a print head with respect to a printing medium, which in particular has a cylindrical shape, is known to the person skilled in the art and is explained, for example, in WO 2022 028 733 A2 cited in the introduction, on pages 5 to 8.

[0036] Figure 1a shows a particularly preferred embodiment of the printing system 100 according to the invention comprising three sections.

[0037] The first section comprises a device for unwinding a printing medium 103 with a first winding core 121, a dancer roller (not shown), and a deflection roller 123, over which the printing medium 103 can be guided to a printing roller with a cylindrical roller shell 117 as a receiving surface for receiving the printing medium 103. Figure 1b shows a partial area of ​​the printing roller as dashed lines, which are connected to the cylindrical roller shell 117.

[0038] The second section comprises the printing roller with the cylindrical roller shell 117 for receiving the printing medium 103. An ink module for printing on the printing medium 103 is assigned to this roller shell 117. The ink module comprises a print bar 119 with five print heads 101, 101', 101", 10T", 101"", which is spaced apart from the roller shell 117. The received print medium 103 can be moved along a circular path via the cylindrical roller shell 117, during which the print medium 103 can be printed on with the rows of nozzles (each shown as a dashed line in the respective print head) of the print heads 100, 10T, 101", 101, 101"". In the printing system 100, the ink module is a single print bar 119.

[0039] The five print heads 101, 10T, 101", 10T", 101"" are assigned an adjustment device, via which the respective print heads 101, 10T, 101", 101'", 101"" can be adjusted one after the other with respect to the print medium 103 by positioning and orientation using a single adjustment actuator 105. An auxiliary device 107 is arranged on the print bar 119 such that with its aid an operative connection of the adjustment actuator 105 with the first print head 101 can be released or created and / or an operative connection with the second print head 101' can be released or created.

[0040] Accordingly, this preferred embodiment generally discloses a printing system 100 with at least one print bar 119, which comprises at least a first and a second print head 101, 101', wherein the printing system 100 is designed such that the first and second print heads 101, 101' can be adjusted in an actuator-based manner with respect to a print medium 103 by positioning and orientation by means of a single adjustment actuator 105, wherein an auxiliary device 107 with the single adjustment actuator 105 is arranged on the print bar 119, such that with the aid of said auxiliary device 107 an operative connection of the adjustment actuator 105 with the first print head 101 can be released or created and / or an operative connection with the second print head 101' can be released or created.

[0041] As the last and third section, the printing system 100 comprises a deflection roller 123', via which the printing medium 103 can be conveyed to the device for winding the printing medium 103 onto a second winding core 125. The device for unwinding the printing medium 103 with the first winding core 121, the printing roller with a cylindrical roller shell 117, the device for winding the printing medium 103 with the second winding core 125, the dancer roller, and the two deflection rollers 123, 123' are each rotatably mounted on a carrier 115 of the printing system 100. The ink module comprising the printing beam 119 is mounted via a bracket to adjustment means (not shown) designed to adjust the distance between the ink module and the cylindrical roller shell 117 or the printing medium 103, wherein the adjustment means are mounted on the carrier (not shown).

[0042] The first device for aligning a print head, which is assigned to the five print heads 101, 10T, 101", 10T", 101"", comprises an orientation device (not shown) and a first shaft a, a', a", a'", a"". The second device for aligning a print head, which is assigned to the five print heads 101, 10T, 101", 10T", 101"", comprises a displacement device (not shown) and a second shaft c, c', c", c"', c"".

[0043] The first shaft a' is functionally connected to the orientation device via which the print head 10T is arranged in the print beam 119, and the second shaft c' is functionally connected to the displacement device via which the print head 10T is arranged in the print beam 119. The other first shafts a, a", a"', a"" and second shafts c, c", c"', c"" are functionally connected to the other orientation and displacement devices of the corresponding print heads 101, 101", 101"', 101"". The first shafts a, a', a", a"', a'" and second shafts c, c", c"', c"" are mechanical aids.

[0044] Each displacement device and the first shaft associated therewith are cooperatively configured such that a rotation of the first shaft is converted into a displacement of a corresponding print head in the y-direction, and each orientation device and the second shaft associated therewith are cooperatively configured such that a rotation of the second shaft is converted into a rotation of the corresponding print head about a rotation axis which is substantially parallel to a current z-axis associated with the print head. M -direction of the printing medium 103.

[0045] Accordingly, according to a preferred embodiment, at least the first and second print heads 101, 105 are each assigned a first mechanical aid for orientation and a second mechanical aid for positioning, such that the desired operative connection can be mediated via the first and / or second mechanical aid, wherein the first and second mechanical aids are preferably an elongated shaft. Figure 1b shows that the print bar 119 from Figure 1a carries a T-shaped linear guide 111 which extends over the print bar 119 in the y-direction. The auxiliary device 107 comprises a carriage 113 and a handle 114, via which the carriage 113 is coupled to the linear guide 111 and via which handle 114 the carriage 113 is arranged to be displaceable along the T-shaped linear guide 111.The adjustment actuator 105 is attached to the carriage 113, with the auxiliary device 107 mounted on and above the pressure beam 119. The pressure beam 119 includes a displacement actuator (not shown) designed to move the carriage 113 back and forth in the y-direction along the linear guide 111 in a controlled manner.

[0046] The adjustment actuator 105 comprises, as shown in detail in Figure 1b, only one motor 129, a first screw head 133 rotatably mounted about a first axis, a second screw head 133' rotatably mounted about a second axis, a drive train which is drivingly connected to the motor 129 and the first and second screw heads 133, 133' in such a way that a rotary movement of the motor 129 is translated into a simultaneous rotary movement of the first screw head 133 about the first axis and of the second screw head 133' about the second axis.

[0047] The drive train comprises a wheel drive designed as a belt drive and a gear drive, wherein, as shown in Figure 1b, the wheel drive comprises: a first spur gear 135, which is axially and rotationally fixedly connected to the first screw head 133 via a first output shaft 136 rotatable about the first axis; a second spur gear 135', which is axially and rotationally fixedly connected to the second screw head 133' via a second output shaft 136 rotatable about the second axis; a motor spur gear 131, which is axially and rotationally fixedly connected to a motor shaft of the motor 129;

[0048] - wherein the motor spur gear 131 is drive-connected to the first and second spur gears 135, 135' via a toothed belt 137.

[0049] The motor spur gear 131 is indirectly drive-connected to the first and second spur gears 135, 135' via the toothed belt 137, wherein the first spur gear 135 is rotatably engaged with a first counter-spur gear 141 which is rotatable about an axis and is axially connected to an additional first spur gear 139 via a shaft, and the second spur gear 135' is rotatably engaged with a second counter-spur gear 14T which is rotatable about an axis and is axially connected to an additional second spur gear 139' via a shaft, and wherein the motor spur gear 131 is directly drive-connected to the additional first and second spur gears 139, 139' via the toothed belt 137.

[0050] As shown in Figure 1a, the axes of rotation about which the spur gears 135, 135', which are directly connected to the drive via the toothed belt, are rotatably mounted are arranged relative to one another in such a way that they form the vertices of a fictitious triangle.

[0051] The second output shaft 136' is shown in Figure 1b in an extended position in which it is operatively connected to the second print head 101', and the first output shaft 136 is shown in a retracted position in which it is not operatively connected to the first print head 101. According to the invention, the auxiliary device 107 and an optical means 109 are provided in the printing system 100, such that they enable automatic adjustment of the five print heads 101, 101", 101", 10T", 101"" using predetermined printed test patterns (not shown). The print heads to be adjusted are successively adjusted in several steps with respect to the print medium 103 by orientation and positioning using an adjustment actuator 105. With the optical means 109, the printed test patterns can be optically captured with the camera 110 of the optical means 109.The optical means 109 and the auxiliary device 107 are designed to cooperate.

[0052] For this purpose, in a first step of the method, the printing medium 103 is printed by ejecting ink in the form of drops via the five printing heads 101, 101', 101", 10T", 101"", while the printing medium 103 is moved in a circular motion over the cylindrical roller shell 117 (see Figure 1a and Figure 1b) and the rows of nozzles of the printing heads 101, 101", 101", 10T", 101"" each print a predetermined test pattern onto the printing medium 103 (not shown).

[0053] In a second step, the x M-y-alignment and y-position of the nozzle rows of the respective print heads 101, 10T, 101", 10T", 101"" are determined using the optical means 109 based on the respective xy-alignment of their test patterns printed on the print medium, and in a third step, an actual-target comparison is carried out in order to identify print heads to be adjusted.

[0054] The target position of a predetermined test pattern is stored in an evaluation unit so that an actual-target comparison can be performed. Furthermore, the target alignment of a predetermined test pattern can be stored in the evaluation unit so that a corresponding actual-target comparison can also be performed. Alternatively, after step two has been completed, an actual alignment of one of the five printed test patterns can be selected as a target value either manually by a user or automatically by the evaluation unit based on predetermined criteria. This can be defined and used as the target alignment for the orientation of the remaining print heads.

[0055] For example, if the xy alignment of a test pattern formed with a print head 101 ,10T, 101", 10T", 101"" on the print medium 103 is not correct, the corresponding x M-y- Alignment of the print head in question can be corrected using the adjustment actuator 105.

[0056] In the present method and case, the XMi-y alignment (see Figure 1b) of the print head 101 was determined as the target alignment by the evaluation unit in an intermediate step after step two and before step three, and in step three, a deviation from the target orientation and position of the print heads 10T, 101", 10T" and 10T" was detected (see Figure 1a). The XMi alignment of the print head 101 has an alignment angle of 90 degrees with respect to the associated x M i-direction.

[0057] In a fourth step, based on the situation shown in Figure 1a and Figure 1b, the deviation of the x M2-y-alignment and the y-position of the print head 10T to be adjusted from the nominal values ​​using the adjustment actuator 105. The XM2-y-alignment of the print head 10T is correct when its nozzle row has an x M 2-y- alignment of 90 degrees to its associated x M 2 direction, which corresponds to the actual orientation of the nozzle row of the print head 101.

[0058] For the corresponding adjustment, the auxiliary device 107 is provided in the printing system 100 in such a way that with its aid an operative connection of the adjustment actuator 105 with and via the first shaft a' with the print head 10T is created and is released again after the adjustment has been carried out by orientation and then an operative connection with and via the second shaft c' with the print head 10T is created and is released again after the adjustment has been carried out by positioning.

[0059] The operative connection between the adjustment actuator 105 and the shaft a' is created by first moving the auxiliary device 107 to a specific position via the linear guide 111 and stopping it there. Subsequently, the second output shaft 136' is moved by the second pneumatically operated actuator 140' along the second axis from its retracted position to an extended position in which the second output shaft 136' is operatively connected to the second pressure head 101'. In this position, the second screw head 133' is functionally connected to the external hexagon of the shaft a'.The operative connection between the adjustment actuator 105 and the shaft a' - and thus between the adjustment actuator 105 and the print head 10T - is released again after the adjustment has been carried out by orienting the print head 101', in that the second output shaft 136' is moved by means of the second pneumatically operating actuator 140' along the second axis from its extended position to the retracted position in which the second output shaft 136 is not operatively connected to the print head 101, in which position the second screw head 133' is no longer functionally connected to the external hexagon of the shaft a'. An operative connection between the adjustment actuator 105 and a shaft a, a", a"" and / or a shaft c, c", c"" is created and released again in accordance with the procedure described in the previous sentence, but in contrast to this with the first output shaft 136 by means of the first pneumatically operating actuator 140 via the first screw head 133.

[0060] In a fifth step, with the aid of the auxiliary device 107, an operative connection of the adjustment actuator 105 with and via the shaft a" with the print head 101" is created and released again after adjustment by orientation, and an operative connection with and via the shaft c" with the print head 101" is created and released again after adjustment by positioning.

[0061] In a sixth step, with the aid of the auxiliary device 107, an operative connection of the adjustment actuator 105 with and via the shaft a'" with the print head 101 is created and released again after the adjustment has been carried out by orientation, and an operative connection with and via the shaft c"' with the print head 101 is created and released again after the adjustment has been carried out by positioning.

[0062] In a seventh step, with the aid of the auxiliary device 107, an operative connection of the adjustment actuator 105 with and via the shaft a"" with the print head 101"" is created and released again after the adjustment has been completed by orientation, and an operative connection with and via the shaft c"" with the print head 101"" is created and released again after the adjustment has been completed by positioning. After completion of the first adjustment process, at least one further test process is carried out in accordance with steps one and two described above, and if necessary, at least one further adjustment process is carried out until all print heads 10T, 101", 101 101"" are in

[0063] are correctly aligned with respect to the print medium 103 and an adjacent print head.

[0064] The print bar 119 from Figure 1b comprises two print head rows (not shown) aligned parallel to one another, which run in the y-direction, wherein the first print head row comprises the first print head 101 and the second print head row comprises the second print head 101', and wherein the first and second screw heads 133, 133' are arranged in such a way that with the aid of the auxiliary device 107 an operative connection of the adjustment actuator 105 via the first screw head 133 with the respective print heads of the first print head row can be released or created and / or an operative connection via the second screw head 133' with the respective print heads of the first print head row can be released or created.

[0065] As shown in Figure 1 b, the printing system 100 comprises a printing roller which is rotatable about an axis and has a cylindrical roller shell 117 which is designed to receive the printing medium 103 and to rotate it in a direction of rotation, wherein the printing beam 119 is associated with the roller shell 117 at a distance therefrom, and wherein the first axis of the first output shaft 136 and the second axis of the second output shaft 136' are aligned in a V-shape with respect to the printing roller, preferably with respect to the axis of rotation of the printing roller.

[0066] The first spur gear 133 and the second spur gear 133' are each designed as bevel spur gears.

Claims

Claims 1. A printing system (100) with at least one printing beam (119) comprising at least a first and a second printing head (101, 101'), wherein the printing system (100) is designed such that the first and second printing heads (101, 101') can be adjusted actuator-based with respect to a printing medium (103) by positioning and orientation by means of a single adjustment actuator (105), wherein an auxiliary device (107) with the single adjustment actuator (105) is arranged on the printing beam (119), such that with its aid an operative connection of the adjustment actuator (105) with the first printing head (101) can be released or created and / or an operative connection with the second printing head (101') can be released or created, characterized in that the adjustment actuator (105) comprises: only one motor (129), a first screw head rotatably mounted about a first axis (133), a second screw head (133') rotatably mounted about a second axis, a drive train,which is drive-connected to the motor (129) and the first and second screw heads (133, 133') in such a way that a rotary movement of the motor (129) is translated into a simultaneous rotary movement of the first screw head (133) about the first axis and of the second screw head (133') about the second axis.

2. Printing system (100) according to claim 1, characterized in that the drive train comprises a wheel drive which is designed as a belt drive or as a belt and gear drive.

3. Printing system (100) according to claim 2, characterized in that the wheel drive comprises: a first spur gear (135) which is axially and rotationally fixedly connected to the first screw head (133) via a first output shaft (136) rotatable about the first axis; a second spur gear (135') which is axially and rotationally fixedly connected to the second screw head (133') via a second output shaft (136') rotatable about the second axis; a motor spur gear (131) which is axially and rotationally fixedly connected to a motor shaft of the motor (129); - wherein the motor spur gear (131) is drive-connected to the first and second spur gears (135, 135') via a toothed belt (137).

4. Printing system (100) according to claim 3, characterized in that the motor spur gear (131) is directly drive-connected to the first and second spur gears (135, 135') via the toothed belt (137).

5. Printing system (100) according to claim 3, characterized in that the motor spur gear (131) is indirectly drive-connected to the first and second spur gears (135, 135') via the toothed belt (137), wherein the first spur gear (135) is rotatably engaged with a first counter-spur gear (141) which is rotatable about an axis and is axially connected to an additional first spur gear (139) via a shaft, and the second spur gear (135') is rotatably engaged with a second counter-spur gear (141') which is rotatable about an axis and is axially connected to an additional second spur gear (139') via a shaft, and wherein the motor spur gear (131) is directly drive-connected to the additional first and second spur gears (139, 139') via the toothed belt (137).

6. Printing system (100) according to claim 4 or 5, characterized in that those axes of rotation about which the spur gears directly connected to the drive via the toothed belt are rotatably mounted are arranged relative to one another in such a way that they form the vertices of a fictitious triangle, in particular an isosceles triangle.

7. Printing system (100) according to one of claims 1 to 6, characterized in that the first output shaft (136) is displaceable along the first axis by means of a first hydraulically or pneumatically and / or electrically operating actuator (140) between an extended position in which the first output shaft (136) is operatively connected to the first print head (101) and a retracted position in which the first output shaft (135) is not operatively connected to the first print head (101), and in that the second output shaft (136') is displaceable along the second axis by means of a second hydraulically or pneumatically and / or electrically operating actuator (140') between an extended position in which the second output shaft (135') is operatively connected to the second print head (101') and a retracted position in which the second output shaft (136') is not operatively connected to the second print head (101').

8. Printing system (100) according to one of the preceding claims, characterized in that the motor (105) is a stepper motor.

9. Printing system (100) according to one of the preceding claims, characterized in that the auxiliary device (107) comprises at least one linear guide (111) and a carriage (113), wherein the carriage (113) is arranged displaceably on the linear guide (111) and the adjustment actuator (105) is attached to the carriage (113), wherein the auxiliary device (107) is mounted on and above the printing beam (119).

10. Printing system (100) according to one of the preceding claims, characterized in that the printing bar (119) comprises two print head rows aligned parallel to one another, wherein the first print head row comprises the first print head (101) and the second print head row comprises the second print head (101'), and wherein the first and second screw heads (133, 133') are arranged in such a way that with the aid of the auxiliary device (107) an operative connection of the adjustment actuator (105) via the first screw head (133) to the respective print heads of the first print head row can be successively released or created and / or an operative connection via the second screw head (133') to the respective print heads of the first print head row can be successively released or created.

11. Printing system (100) according to claim 10, characterized in that the printing system comprises a printing roller which is rotatable about an axis and has a cylindrical roller shell (117) which is designed to receive the printing medium (103) and to rotate it in a direction of rotation, wherein the printing bar (119) is assigned to the roller shell at a distance, and wherein the first axis of the first output shaft (136) and the second axis of the second output shaft (136') are aligned in a V-shape with respect to the printing roller, preferably with respect to the axis of rotation of the printing roller.

12. Printing system (100) according to claim 11, characterized in that the first spur gear (133) and the counter-spur gear (141) rotatably engaged with the first spur gear (133) are designed as a first bevel-spur gear pair and the second spur gear (133') and the counter-spur gear (14T) rotatably engaged with the second spur gear (133') are designed as a second bevel-spur gear pair, wherein preferably one bevel-spur gear of a bevel-spur gear pair is rotated with respect to the other bevel-spur gear of the bevel-spur gear pair.

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