EP3439888B1 - Inkjet printer for marking goods, comprising a write head - Google Patents

Description

The invention relates to an inkjet printer for the labeling of goods according to the preamble of claim 1. Such an inkjet printer is from WO2013 / 120702 A1 known..

The invention relates both to such inkjet printers in the form of hand-held devices, see e.g. WO2013 / 120702 A1 , as well as in the form of stationary devices, see e.g. EP 1 064 153 B1 . Handheld devices are self-sufficient; like cordless screwdrivers, for example, they are equipped with an internal voltage source, in particular an accumulator. In the case of hand-held devices, the pump is preferably a compressed air pump, and in the case of stationary devices, a liquid pump. In the case of stationary devices, the power supply is usually provided externally, for example via the normal power grid.

From the WO 2015/061334 A1 a printing system is known that includes a media transport system configured to transport media along a media path. The printing system includes a printhead module with a fluid inlet extending across the media path, an ink delivery system that supplies ink to the printhead module and includes a main ink supply and a buffer tank, a first pressure control unit that includes an overflow weir across the fluid from a fluid chamber to a sump flows, an ink supply control module coupled to the main ink supply, the buffer tank, and the pressure regulating unit and controlling fluid flow in fluid paths that include a first fluid path that supplies ink from the main ink supply to the buffer tank. A second fluid path supplies ink from the buffer tank to the fluid chamber. A third fluid path picks up ink from the sump and returns the ink to the buffer tank.

The liquid required for the printing process is in the storage container. For this purpose, the WO 2013 / 120702A1 referenced, the disclosure content of which belongs to the disclosure content of the present application in its entirety and is included in this respect. The storage container has to be replaced relatively frequently in practical operation, since the liquid is constantly consumed during pressure and the supply is exhausted after a certain number of printing processes.

The print head must be checked, cleaned and serviced at regular intervals. The printing unit has to be checked particularly frequently. It is responsible for dividing the ink flow locally and into individual droplets, controlled by the controller and depending on the desired print result. For this purpose, a large number of hydraulically controlling devices, for example valves, must be actuated. Typically, the printheads should be every 18 to To be serviced for 24 months. Since deposits and blockages can occur in the hydraulic area, it would be advantageous if the printing unit could be cleaned and serviced as easily as possible.

The other parts of the write head, on the other hand, do not have to be checked or serviced as frequently, they are also significantly less susceptible to contamination and failure.

According to the state of the art, the writing head must be checked for maintenance or in the event of a problem, for example in the case of a hydraulic deposit. As a rule, it is separated from the storage container. The writing head is usually sent to the manufacturer for maintenance, the writing head is relatively heavy, and shipping is expensive.

This is where the invention comes in. It has set itself the task of making an intervention in the writing head, for example to remove a hydraulic blockage and also for maintenance, simpler, so that a problem in the area of the printing unit can be eliminated more easily and the maintenance of the printing unit can be carried out more easily can and it is also possible not to have to remove the storage container during maintenance or repair.

This object is achieved by an inkjet printer having the features of claim 1.

This inkjet printer has a modular structure. The write head, which was previously designed as a unit according to the prior art, is now divided into two individual devices, namely a main body and a print head. The maintenance-intensive and soiling-prone parts are housed in the printhead, in particular the printing unit. The main body accommodates those parts that require relatively little maintenance, that is to say that maintenance is only necessary for a plurality of years, for example every 5 years. In addition, repairs can be expected less often with these parts and clogging can essentially be ruled out.

The invention makes it possible to detach the print head from the main body at any time without having to touch the reservoir. The connection between The main body and reservoir are retained. Due to the self-closing valve or the independent valves, practically no liquid escapes when the main body and printhead are separated. The valves are preferably spring loaded so that they not only close but close relatively quickly as soon as the mechanical separation of the main body and printhead has been carried out, the valves still assisting the separation process. The self-closing valves prevent leakage of liquid on both the main body side and the print head side. A residual amount of ink is lost with each separation, it is preferably very small. It is also a goal to design the valves so that the residual amount is as small as possible.

Typically, only one hydraulic line, called an ink line, is required from the main body to the printhead. On the main body side, the pump feeds liquid into this line. After passing through the coupling in the print head, the line is routed to the printing unit. From there the liquid escapes onto an object to be labeled. It is now advantageous to provide a second ink line offset by 180 ° to the first ink line and also to assign a self-closing valve to it. When assembling the main body and printhead, you can now choose whether to assemble in a 180 ° position or in a zero ° position. The second ink line in the printhead also makes it possible to flush the printing mechanism via the two ink lines when the printhead is detached from the main body and the valves are accessible from the outside in this state.

The electronics usually provided and necessary in the write head, that is to say the control, can be arranged in the main body and / or in the print head. The electronics that control the printing unit are preferably arranged in the immediate vicinity of the printing unit. The division of the control is preferably carried out in such a way that there must be as few electrical connections as possible between the main body and the print head. Preferably there are no electrical connections between the main body and the reservoir.

The mechanical connecting means are preferably designed in such a way that they have axial fitting surfaces which come into contact with one another when they are plugged together and preferably also have holding means, such as, for example a screw thread, a bayonet or axial snap locks. The mechanical fasteners only work in the axial direction. They are at least partially formed by the hydraulic and / or electrical connecting means. The hydraulic connection means each have at least two interacting valves which themselves also produce a mechanical connection. The same applies to the electrical connection means. It is therefore possible not to provide any separate mechanical connecting means. However, it is advantageous to use mechanical connecting means which, after the main body and printhead have been plugged together, hold this connection in the plugged together state. This can be done, for example, by a screw connection with a rotatable coupling ring or rotatable bayonet ring or other suitable mechanical means which prevent an axial separation of the main body and printhead, but are detachable.

Automatically closing valves are normally in the closed state. In this closed state, the valve bodies are acted upon by a closing spring. The valves are opened by the fact that when the coupling and mating coupling are plugged together, the valve bodies of both valves involved are moved into the open state. The valve bodies preferably not only have a defined closed position, but also a maximum open position beyond which they cannot be moved. In order to be able to open both valves when they are plugged together, it is therefore necessary to cover twice the distance between the closed position and the open position when they are plugged together so that both valves can be opened safely.

The coupling and mating coupling preferably each have a tappet which is connected to a valve body of the associated valve; it is preferably formed in one piece with this valve body. It is possible to design the plungers of the coupling and mating coupling differently, so that one plunger forms a receptacle for the other plunger on its front surface, for example one plunger tapers to a point, the other has a corresponding recess. However, it is also possible for the tappets to have a flat design on their front surface and to have an essentially identical design.

The valves are preferably designed so that there is a space between the valve body in the closed state and a parting plane of the coupling area has the smallest possible volume. This so-called residual volume is filled with liquid before the main body and printhead are separated. The remaining volume is lost. It can lead to pollution. In the closed state of the valve, the valve bodies are therefore preferably located in the immediate vicinity of the parting plane of the coupling area, preferably at a distance of less than 3, preferably less than 2 mm. The inner diameter of the valve housing between the valve body and the parting plane is also preferably designed with the smallest possible cross-sectional area, for example it has a diameter of less than 5, in particular less than 4 mm. The cross-sectional dimension of the tappets is also preferably as large as possible. The larger the tappets, the smaller the remaining volume. These measures help to keep the volume as small as possible.

It is advantageous if, when the main body and printhead are joined together axially, the coupling and the mating couplings have the first contact. It is advantageous if the mechanical connecting means are designed in such a way that when the main body and print head are plugged together, a user is forced to correctly orientate the two with respect to one another. In the case of the housings of the main body and print head, which are preferably cylindrical or are delimited by a cylinder, this is the case when the rotational orientation is predetermined by mechanical measures or markings.

Fig. 1:

eine Seitenansicht, teilweise schnittbildlich, eines Tintenstrahldruckers mit einem Druckkopf, einem Hauptkörper und einem Vorratsbehälter,

Fig. 2:

das Detail A aus Fig. 1 und

Fig. 3:

ein zweites Ausführungsbeispiel für einen Tintenstrahldrucker mit einem Druckkopf und einem davon separatem Hauptkörper, der teilweise dargestellt ist.

Further advantages and features of the invention will become more apparent from the remaining claims and from the non-restrictive description that now follows. In the description, reference is made to the drawing, which shows in FIG

Fig. 1:

a side view, partially in section, of an inkjet printer with a print head, a main body and a reservoir,

Fig. 2:

the detail A. Fig. 1 and

Fig. 3:

a second embodiment of an ink jet printer having a printhead and a separate main body, which is partially shown.

The inkjet printer has a write head 20 which is designed in two parts. It consists of a print head 22 and a main body 24. These are in contact along a first parting plane 26. They can be detached or reconnected in the axial direction; the axial direction is at right angles to the first parting plane 26.

In the first embodiment according to the Figures 1 and 2 , but also in the second exemplary embodiment, the housings of the main body 24 and printhead 22 are essentially cylindrical. They can also have a different shape, for example as a prism, for example a square or hexagonal prism. The shape is basically arbitrary.

In a known manner, the print head 22 has outlet openings 28 for ink. They are located on a front surface 30. A printing unit 32, which is located in the printing head 22, is assigned to the outlet openings 28. It is connected to two ink lines 34. Ink can be supplied to the printing unit 32 via each of the two ink lines 34 independently of one another.

A pump 36 for the liquid of the ink droplets emerging from the at least one outlet opening 28 and a filter 38 are arranged in the main body 24. The filter 38 filters the liquid before it is fed to the printing unit 32.

An electrical control 40 is also arranged in the print head 22. It can also be partially accommodated in the main body 24, possibly also completely. It is arranged in such a way that the number of electrical connections that are routed through the first parting plane 26 is as small as possible. The electrical control 40 is connected to at least the printing unit 32 and the pump 36 via lines.

In the first parting plane 26, a coupling area is formed between the print head 22 and the main body 24, which coupling area contains components that are assigned to the print head 22 and contains components that are assigned to the main body 24. These components are discussed below. The coupling area has at least one mechanical connecting means 42. This is shown in the following on the basis of the second exemplary embodiment Figure 3 explained. There is a rotatable ring on the main body 24 axially displaceable, but arranged with a stop in its axial movement limited. It has an internal thread. The print head 22 has an external thread 44 which corresponds to this internal thread. After the print head 22 and main body 24 have been axially plugged together, the connection is mechanically secured, the ring is rotated until it comes to a stop.

The coupling area also includes at least one electrical connecting means 46, which is designed as an electrical plug-in coupling in both exemplary embodiments and has a round socket and a round plug, which are arranged centrally with respect to a central axis 48. Furthermore, the coupling area has at least one hydraulic connecting means. It is formed by two couplings 50, which are arranged on the print head 22 and are structurally identical, and a counter-coupling 52 which is formed on the main body 24 and adapted to the couplings 50. This design in the two exemplary embodiments makes it possible for the print head 22 and the main body 24 to be plugged together in two 180 ° different rotational positions about the central axis 48. The electrical connection means 46 is designed so that the necessary electrical connections are achieved in both plug-in positions.

How to take a look in particular Fig. 3 shows, when the print head 22 and the main body 24 are plugged together, one of the two couplings 50 and the mating coupling 52 first come into contact. At the same time or possibly at a different point in time, the electrical connecting means 46 comes into contact. The two parts of the print head 22 and the main body 24 are pushed together axially in the direction of the central axis 48 until they are in contact in the first parting plane 26. As described above, the fixation can now take place by means of the ring or another axial fixation means.

The inkjet printer also has a reservoir 54. This is releasably connected to the main body 24 on a second parting plane 56. For the connection between the storage container 54 and the main body 24 of the write head 20 and the design of these two parts, reference is made to the two German patent applications file number: 10 2012 202 343.7, filing date 16.02.2012 and file number: 10 2016 106 259.6, filing date 06.04.2016 taken. Their disclosure content is fully incorporated into the disclosure of the present application. From these two patent applications it is known, inter alia, that the storage container 54 has an outer housing and a foil pouch located therein. The film bag communicates via a supply line 58 with the main body 24 and the filter 38 located therein. The interior space between the housing and the film bag is pressurized with air. For this purpose, the pump 36 is designed as a compressed air pump. It is connected to the interior via a compressed air line.

In an alternative, not shown, the main body 24 is not mechanically connected to the storage container 54, but only via at least one connecting line, for example for the ink supply. The latter training is particularly suitable for stationary devices. In this case there is no second parting plane 56.

The hydraulic connection means, that is to say clutch 50 and mating clutch 52, are described in more detail below. For this purpose, in particular Fig. 2 Referenced. In the exemplary embodiments shown, the coupling is arranged in the print head 22, it has a coupling housing 60, which protrudes axially with respect to the first parting plane 26. The mating coupling 52, which is arranged on the main body 24, has a coupling tube 62 which also projects from the first parting plane 26, but in the opposite direction to the coupling housing 60, and engages in the coupling housing 60 when it is assembled. This creates a mechanical connection.

The coupling 50 and the mating coupling 52 each have a valve housing 64, a valve body 66, a closing spring 68 and a plunger 70. The valve body 66 is axially movable in the valve housing 64 between an open position, which is shown in FIG Fig. 1 can be seen. The valve body 66 has a tappet 70 which projects towards the other coupling part and is always located within the coupling housing 60 or the coupling tube 62, so that it is protected. In the exemplary embodiment shown, the tappets 70 are designed differently, one tappet 70 with a pointed, in particular conical end region is provided, the other has a correspondingly designed trough, for example a V-shaped trough. As a result, the two tappets 70 come together, as is the case Figure 2 can be seen, for sure. In the closed state, the valve bodies 66 rest on the valve housing 64 in order to create a seal To improve there, a ring seal is inserted. As FIG. 2 shows in particular, these two ring seals are arranged at a relatively small distance from one another, the clear distance is less than 2, preferably less than 1 mm, in the coupled state. The plungers 70 are located within these ring seals. In the embodiment shown according to the first exemplary embodiment, the male plunger 70 of the print head 22 protrudes axially more strongly than other plungers 70. The other plunger 70 protrudes at least 50% less. When the valve is open, the first parting plane preferably remains on one side.

When coupling 50 and mating coupling 52 are plugged together, the tappets 70 are initially in contact. When plugged together, the path is about 150 to 200% of the distance that a single valve body 66 carries out from the closed to the open position. At least one valve body 66 is moved to the fully open position; the other does not have to be fully reached in the fully open position. In the assembled state of main body 24 and print head 22, at least one valve body 66 is in contact with an end stop of valve body 66. The end stop limits the travel of valve body 66 in valve housing 64.

Each of the two ink lines 34 is connected to a coupling 50. The main body 24 has only one counter-coupling 52, the other is not formed. As a result, only one of the two possible feed paths for the ink is closed. The valve of the in Fig. 1 Coupling 50 shown above remains closed. As a result, no ink can escape through the upper ink line 34. It forms a dead end.

In order to be able to flush the printing unit 32, the print head 22 is connected to a body (not shown here) which is designed similarly to the main body 24, but has two counter-couplings 52, which are each connected to a flushing line.

In the inkjet printer for the inscription of goods with a writing head 20 and a reservoir 54 for liquid which flows through outlet openings 28, the writing head 20 is designed in two parts. It consists of a main body 24 and a print head 22. In the print head 22 is a printing mechanism 32 arranged. A coupling area is formed between the print head 22 and the main body 24, each having at least one mechanical connection means 42, an electrical connection means 46 and a hydraulic connection means. The hydraulic connecting means has a coupling 50 in the print head 22, which has at least one automatically closing valve, and a mating coupling 52 in the main body 24, which has an automatically closing valve. The automatically closing valves are each in an open state only when the coupling 50 and mating coupling 52 are joined together. The main body 24 is detachably connected to the reservoir 54.

The ink jet printer for the labeling of goods with a writing head 20 and a reservoir 54 for liquid which flows through outlet openings 28, the writing head 20 is formed in two parts. It consists of a main body 24 and a print head 22. A print unit 32 is arranged in the print head 22. A coupling area is formed between the print head 22 and the main body 24, each having at least one mechanical connection means 42, an electrical connection means 46 and a hydraulic connection means. The hydraulic connecting means has a coupling 50 in the print head 22, which has at least one automatically closing valve, and a mating coupling 52 in the main body 24, which has an automatically closing valve. The automatically closing valves are each in an open state only when the coupling 50 and mating coupling 52 are joined together. The main body 24 is detachably connected to the reservoir 54.

Terms such as essentially, preferably and the like, as well as information that is possibly to be understood as imprecise, are to be understood in such a way that a deviation of plus minus 5%, preferably plus minus 2% and in particular plus minus one percent from the normal value is possible.

List of reference symbols

20th

Print head

22nd

Printhead

24

Main body

26th

first parting plane

28

Outlet opening

30th

Front surface

32

Printing unit

34

Ink line

36

pump

38

filter

40

control

42

mechanical lanyard

44

External thread

46

electrical connector

48

Central axis

50

coupling

52

Mating coupling

54

Storage container

56

second parting plane

58

Feed line

60

Clutch housing

62

Coupling tube

64

Valve body

66

Valve body

68

Closing spring

70

Plunger

72

Ring seal

Claims (12)

1. An ink jet printer for labelling goods,

   - having a writing head (20), which a) comprises at least one outlet opening (28) for ink droplets on a front face (30), b) a print mechanism (32) assigned to this outlet opening (28), c) a pump (36) for a liquid of the ink droplets, d) if required a filter (38) for the liquid and e) an electrical control (40), and

   - having at least one reservoir (54) for liquid, which flows through the outlet opening (28), such as for example ink, pigment or solvent, wherein the reservoir (54) is detachably connected to the writing head (20),

   characterized in that the writing head (20) is constructed of two parts and consists of a main body (24) and a printing head (22), in that if required the pump (36) and/or the filter (38) are located in the main body (24), in that in the printing head (22)the printing mechanism (32) is arranged, and in that between printing head (22) and main body (24) a coupling region is formed, which each comprises at least one mechanical connecting means (42), one electrical connecting means (46) and one hydraulic connecting means, wherein the hydraulic connecting means comprises at least one automatically closing valve of a coupling (50) in the printing head (22) and an automatically closing valve of a counter-coupling (52) in the main body (24), the automatically closing valves, in the joint state of coupling (50) and mating coupling (52), are each in an opening state and the automatically closing valve is normally open.
2. The ink jet printer according to Claim 1, characterized in that coupling (50) and mating coupling (52) each comprise a pushrod (70), that the pushrod (70) is each connected to a valve body (66) of the associated valve, in that the valve body (66) is loaded by a closing spring (68), and in that in the joint state of main body (24) and printing head (22) the pushrods (70) are in contact with one another.
3. The inkjet printer according to any one of the preceding claims, characterized in that the printing head (22) comprises two identically designed couplings of two automatically closing valves, which are arranged offset by 180° relative to one another and the printing head (22) can be coupled to the main body (24) in two rotary positions that are distinct by 180° from one another.
4. The inkjet printer according to any one of the preceding claims, characterized in that at least one of the three connecting means, preferentially at least two connecting means are designed as plug and socket that can be connected in the axial direction.
5. The inkjet printer according to any one of the preceding claims, characterized in that on one of main body (24) or printing head (22) an external thread (44) and on the other one a freely rotatable ring with a fitting internal thread and with a stop is arranged and held, and in the joint state of main body (24) and printing head (22) the ring is screwed on to the external thread (44).
6. The inkjet printer according to any one of the preceding claims, characterized in that upon joining main body (24) and printing head (22), coupling (50) and mating coupling (52) have contact first.
7. The inkjet printer according to any one of the preceding claims, characterized in that at least one part of the electrical control (40) is located in the main body (24).
8. The inkjet printer according to any one of the preceding claims, characterized in that a primary voltage supply either in the form of a power accumulator or of a connecting plug is provided in the main body (24).
9. The inkjet printer according to any one of the preceding claims, characterized in that at least one part of the electrical control (40) is arranged in the printing head (22).
10. The inkjet printer according to any one of the preceding claims, characterized in that the reservoir (54) is detachably connected to the main body (24).
11. The inkjet printer according to any one of the preceding claims, characterized in that the pump (36) and/or the filter (38) are located in the main body (24).
12. The inkjet printer according to any one of the preceding claims, characterized in that coupling (50) and mating coupling (52) each comprise a valve housing (64), in that the valve body (66) is movable in the valve housing (64) between a closing position and an opening position, and in that in the joined state of main body (24) and printing head (22) at least one valve body (66) is in contact with an end stop of the valve body (66).

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