DE102013106211A1 - Inkjet printer with transfer carriage and method for this - Google Patents

Abstract

An inkjet printer (10) with a stationary printing unit (14) has a cleaning unit (17) below the printing unit (14). A movable transfer printing carriage (18) is arranged in the space (R) between the printing unit (14) and the cleaning unit (17) and guides a recording medium (12). In the printing mode, the transfer printing carriage (18) is positioned between the printing unit (14) and the cleaning unit (17). In a maintenance operating state, the transfer printing carriage (18) is moved out of the room (R) in order to allow the cleaning unit (17) to access the print heads.

Description

The invention relates to an ink jet printer of high printing power for printing a web-shaped recording medium with ink. Furthermore, the invention relates to a method for printing a web-shaped recording medium with ink.

For single-color or multi-color printing of a web-shaped recording medium, high-pressure inkjet printers can be used. In these ink-jet printers, there is provided a printing unit having a plurality of printing bars each having a plurality of printing heads from the nozzles of which ink droplets are transferred onto the recording medium. Due to different pressure utilization, all nozzles of the print heads are not constantly activated during the printing process, so that there is a risk of dehydration or clogging if the nozzles are not activated for a long time. It is therefore to be provided that the print heads are cleaned of thickened ink at predetermined maintenance time intervals and / or all nozzles of the print heads are flushed through.

The DE 10 2010 037 829 A1 describes an ink jet printer in which the printing unit can be moved from a printing operating position above the path of the recording medium in a maintenance position, which is located laterally to the path of the recording medium. In this maintenance position, the printheads are accessible and their nozzle surfaces can be cleaned. To the printing unit of a high-performance printer, a plurality of electrical and optical lines for power supply and for transmitting the drive signals for the print heads and a plurality of mechanical lines and hoses for supplying ink are connected. Due to the necessary movement of the printing unit, these feeders are designed to be highly flexible and large-volume and long drag chains are necessary for guiding these lines. In this known device concept, the technical complexity is therefore relatively large and also increases the space requirement because of the lateral movement of the printing unit.

It is an object of the invention to provide an ink jet printer and a method for operating an ink jet printer, in which the equipment cost is reduced and the technical reliability is improved.

This object is achieved for an ink jet printer by the features of claim 1 and a method by the features of claim 8. Advantageous developments are specified in the dependent claims.

According to the invention, a cleaning unit for cleaning the print heads is arranged below the printing unit. A transfer carriage for guiding the recording medium can be moved into a space between the upper printing unit and the lower cleaning unit, and moved out of this space again. The transfer carriage is positioned in a printing operation state between the printing unit and the cleaning unit, so that the printing bars with the plurality of printing heads can transfer ink to the recording medium. In this state, the recording medium at least partially wraps around the transfer carriage. In a maintenance operating state, the transfer carriage has moved out of the space between the printing unit and the cleaning unit, so that an access of the cleaning unit to the printing heads of the printing unit is provided. In this condition, the printheads can be cleaned.

In the device concept according to the invention, the printing unit is not moved laterally to the transport path of the recording medium in a maintenance position, but the printing unit can remain stationary in relation to the transport path of the recording medium. The various feeds to the printing unit, e.g. electrical and optionally optical lines for the control signals (LAN, pressure data, sensors), electrical cables, mechanical cables and hoses, can be carried out substantially stationary or with small loops for motion compensation and it is no drag chain to guide the cables, hoses and lines needed to allow a movement of the printing unit. In this way, the space required for the printer is reduced. Due to the largely stationary arrangement of the feeders to the printing unit, the technical reliability is improved because a rupture of the leads due to high movement load is not to be feared. A large space savings also results from the fact that only the low transfer carriage and not the printing unit or cleaning unit is moved.

According to one embodiment, the cleaning unit assumes a lower position in the printing operation state and an upper position in the maintenance operation state, wherein a lifting device is provided which moves the cleaning unit selectively in the upper position or in the lower position.

In the maintenance mode state, the recording medium is moved out of the space between the printing unit and the cleaning unit with the aid of the transfer carriage, so that access of the cleaning unit to the nozzle surfaces of the print heads is possible. In this maintenance operation Condition, the cleaning unit can be raised to make mechanical contact with the printheads. In this way, for the cleaning process, the printing unit itself does not have to be moved (as is necessary in the prior art).

It is advantageous if the transfer carriage is movable in the direction of transport of the recording medium back and forth. As the transport direction of the recording medium, the direction is meant, in which the recording medium is moved below the fixed printheads during printing. Typically, this direction is the device longitudinal axis of the inkjet printer. When moving the transfer carriage in the direction of this device longitudinal axis, the width of the printer remains narrow, which brings further technical advantages for the size of the printer. For example, For example, the electrical signal lines for the high frequency signals to drive the printheads may be short. The direction of movement of the transfer carriage can be carried out starting from the printing operating state for setting the maintenance operating state in the transport direction of the recording medium or opposite to this transport direction of the recording medium.

In an alternative, the device concept may also be designed so that the transfer carriage is moved laterally out of the space between the printing unit and the cleaning unit in order to set the maintenance operating state. The longitudinal axis of the transfer carriage runs in this maintenance mode state parallel to the transport direction of the recording medium in the printing operation state.

A further embodiment provides that a compensating device and a deflection roller in combination with a roller keeps the length and position of the recording medium constant during the movement of the transfer carriage during the change of the operating states. It is thereby achieved that when changing from the printing operation state to the maintenance operation state (in which cleaning of the print heads takes place) and back to the printing operation state, the printing operation can be continued at the same place where it has been interrupted. In addition, further processing of the record carrier, e.g. in a fixing unit, length neutral and position neutral. That the record carrier in the printer is not shifted forward / backward is also positive for position determining actuators (e.g., rotating frames) in front of the printing unit.

According to another aspect of the invention, there is provided a method of operating an ink jet printer. The advantages achieved by this method are substantially in accordance with the advantages previously described in connection with the inkjet printer.

Embodiments of the invention are explained below with reference to the figures. In the figures shows schematically

1 a part of an ink jet printer in the print mode,

2 the printer 1 in the maintenance operation state, and

3 an overview representation in plan view of the arrangement of the transfer carriage in the maintenance mode state.

1 shows a part of an inkjet printer 10 for printing a web-shaped recording medium 12 with ink in a side view. The arrows on the record carrier 12 mark his transport movement. The inkjet printer 10 is a high-performance printer that supports the record carrier 12 at high speed, typically up to 3 m / s can print in multi-color operation. As a record carrier paper, packaging material, fabric, cardboard, films made of plastic (sometimes including metal) or hybrid material (plastic areas in paper) may be provided.

The inkjet printer 10 includes a printing unit 14 in which several pressure latches 16 are arranged, each printing a specific color. The pressure bolts 16 extend over the entire width of the recording medium 12 and may include one or more printheads from which nozzles ink droplets onto the recording medium 12 be ejected. When printing, the pressure bars are 16 stationary and the record carrier 12 becomes along a transporting direction T under the printing unit 14 moved forward. Below the printing unit 14 is a cleaning unit 17 arranged, the cleaning elements, such as doctor blade, wiping elements, ink collecting trays and / or caps for the pressure bolt 16 contains.

In a room R with the height w2 between the pressure unit 14 and cleaning unit 17 is a transfer carriage 18 arranged, a variety of rollers 20 (Only one is designated) to guide the record carrier 12 contains. The transfer carriage 18 is moveable. In the illustrated printing operating state is the transfer carriage 18 fully driven into the room R, so that the recording medium 12 the different pressure locks 16 facing and can be printed with ink. In this state, the recording medium forms 12 a loop open to the left and is over Pair of rollers with rollers 22 and 23 and a pulley 24 the rollers 20 fed.

In the printing operation state, the recording medium becomes 12 over another pulley 26 discharged and supplied to subsequent units such as a fuser or dryer (not shown).

The transfer carriage 18 is slidably mounted on guide rails (not shown) and can be moved to set a maintenance operation state to the left in a maintenance position shown in dashed lines, wherein it covers the path W1. This is done with the transfer carriage 18 the pulley 24 moved so that the length of the loop of the recording medium 12 around the transfer carriage 18 is essentially maintained around. Only at the left end of the loop can be seen that a certain length difference of the loop between the printing operation state and the maintenance operation state can arise. This is done with the help of a balancing device 28 balanced, at the pulley 26 with the help of a lever arm 30 around a pivot axis 32 is pivoted and raised to compensate for this difference in length. For neutral length compensation and the stationary pulley serves 22 that the record carrier 12 deflects. With the help of the equalization device 28 becomes the movement of the transfer carriage 18 Total length neutralized, so that the record carrier 12 after the pulley 26 and before the roles 22 and 23 no change in position due to this movement. The length of the loop of the recording medium 12 between the roles 22 . 23 and the guide roller 26 stay constant. This is very advantageous, because in this way a downstream fixing or drying station of the recording medium 12 fed without length variation or position variation. A double fixation or drying of sections is thereby avoided. A possibly upstream positioning device for the recording medium in the running direction (eg rotating frame) is also not adversely affected due to the length / position neutrality. Even when switching from the printing operation state to the maintenance operation state and back to the printing operation state, there is no length change or position change, resulting in a continuous and smooth operation. The rollers 22 . 23 . 24 . 20 . 26 are free running to a rupture of the record carrier 12 to prevent.

2 shows the inkjet printer 10 in the maintenance mode state, wherein like elements having largely the same function have the same reference numerals. In this operating state is the transfer carriage 18 to the left in the 2 method. The cleaning unit 17 has been raised from its lower position (shown in dashed lines) to an upper position around the path w2, so that the cleaning unit 17 with their cleaning elements in direct contact with the Druckriegeln 16 and their printheads can be cleaned. The record carrier 12 is about the stationary role 22 deflected and is from the pulley 24 Using the transfer carriage 18 has been moved around the path W1, deflected, so that the loop length of the recording medium 12 around the transfer carriage 18 has remained essentially the same. With the help of the upwardly adjusted pulley 26 and the balancing device 28 , is the movement for the record carrier 12 after the pulley 26 on length / position neutral. The variably suspended pulley 26 may be spring loaded and also serves to maintain a constant web tension.

In the after the 1 and 2 the arrangement shown is the transfer carriage 18 to set the maintenance mode state to the left in the transport direction T move. It is also possible the transfer carriage 18 to move right against the transport direction T for setting the maintenance mode state. In this case, the supply of the recording medium would have to 12 on the right edge of the cleaning unit 17 respectively.

3 shows a schematic representation of a plan view of the various possibilities, the transfer carriage 18 to be arranged in the maintenance mode state. In the plan view is the transfer carriage 18 shown with solid lines in print mode. The longitudinal axis of the transfer carriage 18 is parallel to the transport direction T of the recording medium. Various maintenance positions WP1, WP2, WP3 and WP4 are possible for the maintenance operation state and are shown in dashed lines. In the maintenance position WP1 is the transfer carriage 18 Move in the transport direction T. This maintenance position WP1 agrees with that in the 1 and 2 shown match. The maintenance position WP2 is arranged opposite to the transport direction T. The maintenance positions WP3 and WP4 correspond to lateral arrangements in which the transfer carriage 18 is moved transversely to the transport direction T. At these positions WP3 and WP4 there is lateral space for the transfer carriage 18 needed, which leads to a widening of the printer. The paper guide is also much more expensive. A pressure system with the WP1 maintenance position is to be aimed for.

The invention and the embodiments shown various technical advantages are achieved. All massive units of the printer, in particular the printing unit, can be fixedly mounted or only slightly moved, such as the cleaning unit 17 , Small loops to Motion compensation for various connection cables, such as electrical cables for LAN transmission, sensors, actuators, optical-electrical data buses, etc. and hoses for ink supply, cooling lines etc. are optimally short, largely stationary and can be laid without a drag chain. A space requirement for the drag chain, which is necessary in the prior art for a movement of the relatively large printing unit, is eliminated. A separate installation of critical and uncritical connection lines in the prior art is easier to implement in the device concept according to the invention and high electrical shielding classes are not required. The necessary tanks for ink, pumps, heaters, etc. can be mounted in a suitable service-friendly position in the printer.

For the movement of the transfer carriage relatively small drives and simple guide rails are sufficient. For the necessary connection cables for the movable transfer carriage, the technical complexity, even for a possibly necessary drag chain, comparatively small.

The transfer carriage requires a small space compared to the printing unit and the cleaning unit, so that the space required for its movement compared to the movement of a printing unit and / or a cleaning unit can be small. When the transfer carriage moves in the transport direction, the width of the printer is low and the lateral access to aggregates in the printer is facilitated.

When the cleaning station 17 In the lower position and the Umsetzschlitten in the maintenance mode state, there is a service room below the printing unit to perform manual maintenance can.

Due to the relatively low weight of the transfer carriage this can be moved relatively quickly and without much energy. If a length compensation is provided, the paper length in the printer remains constant and the position of a paper web is the same after a cleaning process and the restart of printing.

Also the insertion of the record carrier 12 can be relieved with this device concept. For this purpose, the deflection roller 24 before inserting a record carrier 12 to remove or decouple and the transfer carriage 18 is when inserting the record carrier 12 to above the transfer carriage 18 in the position in the maintenance mode state (see 2 ). The record carrier 12 is up behind the pulley 26 guided and is held there and the transfer carriage 18 is moved to the printing operation state. When the transfer carriage 18 in this print mode state ( 1 ), the transfer roll becomes 24 again inserted or coupled and the required loop of the recording medium to the transfer carriage is completed.

Due to the fixed position of the printing unit 14 in the printer 10 and the relatively small stroke w2 of the cleaning unit 17 can change the overall height of the printer 10 be kept low, resulting in a compact design of the printer 10 leads.

The arrangement of the printing unit above the cleaning unit is optimal with respect to a modular structure of a printer. Areas of liquids (ink, cleaning liquids, etc.) are located in a first area or module, the post-processing of the recording medium, e.g. Fixation, drying, etc. is located in another area or module.

LIST OF REFERENCE NUMBERS

10

Inkjet Printer

12

record carrier

14

printing unit

16

pressure lock

17

cleaning unit

18

Umdruckschlitten

20

roll

22, 23,

roll

24

idler pulley

26

idler pulley

28

balancer

30

lever arm

32

swivel axis

T

transport direction

WP1, WP2,

WP3, WP4

maintenance items

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102010037829 A1 [0003]

Claims (10)

Inkjet printer ( 10 ) for printing a web-shaped recording medium ( 12 ink) comprising: a printing unit ( 14 ) with several pressure locks ( 16 ), each having one or more printheads, one below the printing unit ( 14 ) arranged cleaning unit ( 17 ) for cleaning the printheads, and one in the space (R) between the printing unit ( 14 ) and cleaning unit ( 17 ) and extendable out of this transfer carriage ( 18 ) for guiding the record carrier ( 12 ), wherein the transfer carriage ( 18 ) in a printing operation state between printing unit ( 14 ) and cleaning unit ( 17 ) and in a maintenance operating state from the space between the printing unit ( 14 ) and cleaning unit ( 17 ) and an access of the cleaning unit ( 17 ) on the printheads of the printing unit ( 14 ) is created. An ink jet printer according to claim 1, wherein the cleaning unit ( 17 ) assumes a lower position in the printing operation state and an upper position in the maintenance operation state, wherein a lifting device is provided, the cleaning unit ( 17 ) moved either in the upper position or in the lower position. Ink jet printer according to one of the preceding claims, in which the printing unit ( 14 ) in the printer ( 10 ) is arranged stationary. An ink jet printer according to claim 3, wherein the printing unit ( 14 ) electrical and / or liquid lines are connected, which are largely stationary in a housing of the printer ( 10 ) are arranged. Inkjet printer according to one of the preceding claims, in which the transfer carriage ( 18 ) in the transport direction (T) of the recording medium ( 12 ) is movable back and forth. Ink-jet printer according to one of the preceding claims, in which rollers ( 22 . 23 ), a pulley ( 24 ) and a compensating device ( 28 ) provided during the movement of the transfer carriage ( 18 ) the length and position of the record carrier ( 12 ) in the printer. Ink jet printer according to one of the preceding claims, in which the cleaning unit ( 17 ) Contains cleaning elements that clean the printheads in the service mode condition. Method for operating an inkjet printer ( 10 ) for printing a web-shaped recording medium ( 12 ) with ink: in which a printing unit ( 14 ) several pressure latches ( 16 ), each having one or more print heads, a cleaning unit ( 17 ) to clean the printheads below the printing unit ( 14 ), a transfer carriage ( 18 ) for guiding the record carrier ( 12 ) in the space (R) between the printing unit ( 14 ) and cleaning unit ( 16 ) can be moved in and out of this, wherein the transfer carriage ( 18 ) in a printing operation state between printing unit ( 14 ) and cleaning unit ( 17 ) and in a maintenance operating state from the space between the printing unit ( 14 ) and cleaning unit ( 17 ) and an access of the cleaning unit ( 17 ) on the printheads ( 16 ) of the printing unit ( 14 ) is created. Method according to Claim 8, in which the cleaning unit ( 17 ) is moved to a lower position in the printing operation state and to an upper position in the maintenance operation state. Method according to one of the preceding claims, in which by means of a compensating device ( 28 ) and roles ( 22 . 23 . 24 ) during the movement of the transfer carriage ( 18 ) the length and position of the record carrier ( 12 ) is kept constant in the printer.

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