Arrangement and method for supplying a cleaning liquid to a print head unit of an inkjet printing device

Abstract

In an arrangement (100, 200) for supplying a printhead cleaning unit of an inkjet printer with a cleaning fluid (103), a supply line (110) is provided which can be connected to the printhead cleaning unit. A cleaning fluid (103) can be supplied to the printhead cleaning unit via the supply line (110). Furthermore, the arrangement (100, 200) includes a means (108) for transporting the cleaning fluid (103) at least through the supply line (110), wherein the cleaning fluid (103) can be supplied to the means (108) for transport via a feed line (104). The arrangement also includes a means (106) for determining the conductivity of the cleaning fluid (103) in the feed line (104). Methods for controlling the arrangement are also provided.

Description

[0001] The invention relates to an arrangement for supplying a printhead cleaning unit of an inkjet printing device with a cleaning fluid. Furthermore, the invention relates to methods for controlling the arrangement.

[0002] Inkjet printing devices generally include print heads that apply ink to a recording medium. To ensure consistently high quality, print heads must be cleaned regularly. For example, print heads can be rinsed with a cleaning fluid and a printhead cleaning unit. It is important to use only cleaning fluids that are specifically designed for the print heads and / or the ink used. If other cleaning fluids are used, the cleaning fluid may react with the print heads and / or the ink used, resulting in clogged or damaged print heads.

[0003] Known solutions for preventing this damage to printing devices utilize barcodes or RFID tags attached to cleaning fluid containers that contain information about the fluid they contain. When such a container is installed in a printing device, the barcodes or RFID tags can be read to ensure that only fluids compatible with the particular printing device and ink used are used.

[0004] The disadvantage of such solutions, however, is that the contents of a cleaning fluid container are not checked; only the label is inspected. Therefore, if the label is damaged, if a label is applied by mistake, or if the cleaning fluid is contaminated, the printing device can still be damaged.

[0005] It is an object of the invention to provide an arrangement for supplying a print head cleaning unit of an inkjet printing device with a cleaning fluid, which ensures increased safety against damage to the inkjet printing device by unsuitable cleaning fluids.

[0006] This object is achieved by an arrangement and method having the features of the independent claims. Advantageous further developments are specified in the dependent claims.

[0007] In an arrangement for supplying a printhead cleaning unit of an inkjet printing device with a cleaning fluid according to a first aspect, a supply line is provided that can be connected at least to the printhead cleaning unit. A cleaning fluid can be supplied to the printhead cleaning unit via the supply line. The arrangement further comprises a means for transporting the cleaning fluid at least through the supply line, wherein the cleaning fluid can be supplied to the transport means via a supply line. The arrangement further comprises a means for determining the conductivity of the cleaning fluid in the supply line.

[0008] The conductivity is, in particular, an electrical conductivity. Thus, the means for determining the conductivity of the cleaning fluid is, in particular, a sensor with which the electrical conductivity of the cleaning fluid can be determined. For example, the sensor can be an inductive or a conductive sensor.

[0009] The means for transporting the cleaning fluid can, for example, be a cleaning fluid pump. In a cleaning operating mode, the means for transporting the cleaning fluid, in particular, first transports the cleaning fluid through the supply line. The cleaning fluid then flows through the means for transporting the cleaning fluid and then through the supply line to the printhead cleaning unit. The supply line can, for example, be fed from a cleaning fluid reservoir. The arrangement preferably comprises the printhead cleaning unit.

[0010] With the help of a print head of an inkjet printing device, print images can be applied to recording media in the form of print dots. Inkjet printing devices typically comprise multiple print heads. An inkjet printing device is known, for example, from document DE 10 2014 106 424 A1.

[0011] Printheads comprise a multitude of print nozzles, each capable of applying ink droplets of a variable volume to the recording medium in the form of print dots. In practice, each printhead can comprise several hundred to several thousand print nozzles directed at the recording medium. To ensure consistent print quality, for example, to prevent or remedy clogged print nozzles, printheads are cleaned, specifically flushed, regularly or as needed using cleaning fluids.

[0012] Liquids, such as inks and cleaning fluids, can often be distinguished by their conductivity. For example, a concentrated aqueous solution of an electrolyte often has a higher conductivity than tap water, and tap water, in turn, often has a higher conductivity than organic solvents. These different liquids are also usually immiscible with each other, meaning they do not mix to form a homogeneous phase. Furthermore, components dissolved in one liquid can precipitate when mixed with another liquid. Therefore, it is often important to avoid mixing incompatible liquids. Furthermore, deviations from the expected conductivity of a liquid could indicate undesirable impurities in the liquid.

[0013] The arrangement makes it possible to reliably determine the conductivity of the cleaning fluid used, especially before the cleaning fluid enters a print head or before the cleaning fluid mixes with the ink of the inkjet printer. This prevents the use of a cleaning fluid that is not compatible with the ink or the material of the print head. It also allows contaminated cleaning fluids to be detected. This allows, for example, the undesirable effects described above to be avoided.

[0014] Preferably, the means for determining conductivity is arranged at a measuring point along the supply line, and the supply line forms a first section of the supply line between the measuring point and the transport means. The means for determining conductivity thus determines the conductivity of the cleaning fluid in the supply line at least at the measuring point. The means for determining conductivity is thus, at least in the cleaning operating mode, upstream of the transport means in the flow direction of the cleaning fluid, such that the cleaning fluid first flows past the means for determining conductivity and then through the transport means. This ensures that the conductivity of the cleaning fluid can be determined particularly quickly.

[0015] It is particularly preferred that the first section of the supply line is at least long enough that the liquid transported through the first section only reaches the transport means when a conductivity measurement result is available. The conductivity measurement result is determined with the aid of the means for determining the conductivity. In particular, the length of the first section of the supply line depends on a cross-sectional area (m2) of the first section of the supply line, a flow rate (m3 / s) of the cleaning liquid through the first section of the supply line generated by the transport means, and a time (s) required for measuring the conductivity and reaction of the transport means.This allows the transport system to be shut down as soon as a conductivity measurement result of a cleaning fluid transported into the system for the first time deviates from the expected conductivity, even before the cleaning fluid has already been transported into the transport system or into the supply line. After shutting down the transport system, the supply line containing the different cleaning fluid can, for example, be easily replaced or cleaned. This prevents further spread or penetration of the different cleaning fluid into the system, the print head cleaning unit, or a print head.

[0016] Preferably, the supply line is reversibly connected to the transport means. This allows for easy replacement of the supply line.

[0017] Preferably, the arrangement further comprises a cleaning fluid reservoir, and the supply line is connected to the cleaning fluid reservoir. This allows for easy storage and supply of the cleaning fluid.

[0018] It is particularly preferred that the arrangement further comprises a return line and at least the return line, the cleaning fluid reservoir, the means for transporting the cleaning fluid and the supply line with the means for determining the conductivity form a cleaning fluid circuit. The cleaning fluid can be transported within the cleaning fluid circuit with the aid of the transport means. This can also be carried out repeatedly or for a specific period of time. This ensures that the conductivity of the cleaning fluid can be determined particularly accurately and without consumption of the cleaning fluid with the aid of the means for determining the conductivity. In particular, the supply line can also be designed to be particularly short. Furthermore, this makes it particularly easy to flush the cleaning fluid circuit if an unwanted cleaning fluid was previously transported into the supply line.

[0019] Preferably, in a measuring operating mode, a control unit of the arrangement controls at least the means for transporting the cleaning fluid through the cleaning fluid circuit. This allows the conductivity of the cleaning fluid to be determined particularly accurately and without consuming the cleaning fluid using the means for determining conductivity.

[0020] Preferably, in a cleaning operating mode, the control unit of the arrangement controls at least the means for transporting the cleaning fluid to the printhead cleaning unit. This ensures that the cleaning fluid can be transported directly to the printhead cleaning unit.

[0021] The arrangement preferably comprises a valve which, in a first valve position, connects the means for transporting the cleaning fluid and the return line, such that the cleaning fluid can only be transported through the cleaning fluid circuit, and in a second valve position, connects the means for transporting the cleaning fluid to the supply line or the print head cleaning unit, such that the cleaning fluid can only be supplied to the supply line or the print head cleaning unit. This enables particularly secure separation of the cleaning fluid circuit from the supply line or the print head cleaning unit. Furthermore, the cleaning fluid circuit can be flushed particularly easily if an undesired cleaning fluid was previously transported into the supply line. The valve can, for example, be a 3 / 2-way valve.

[0022] In a further aspect, a method is provided for controlling an arrangement for supplying a printhead cleaning unit of an inkjet printing device with a cleaning fluid. In the method, the cleaning fluid is transported at least through one supply line with the aid of the transport means, and the conductivity of the cleaning fluid in the supply line is determined with the aid of a means for determining the conductivity of the cleaning fluid. Furthermore, the means for transporting the cleaning fluid is switched off if the determined conductivity of the cleaning fluid deviates from a preset conductivity value or a conductivity range. This enables particularly safe use of cleaning fluids. The preset conductivity value or range can, for example, depend on the ink used in the inkjet printing device.

[0023] In a further aspect, a further method for controlling an arrangement for supplying a printhead cleaning unit of an inkjet printing device with a cleaning fluid is provided. In the further method, the cleaning fluid is transported through the cleaning fluid circuit with the aid of the transport means; in particular, the valve is brought into the first valve position. Preferably, the cleaning fluid is transported for a preset volume or a preset time. Furthermore, in the method, the conductivity of the cleaning fluid in the supply line is determined with the aid of a means for determining the conductivity of the cleaning fluid.Furthermore, the valve is switched to a second valve position, in which the means for transporting the cleaning fluid is connected to a supply line, if the determined conductivity of the cleaning fluid is within a preset conductivity value or conductivity range. Thus, after successful determination and suitability, the cleaning fluid can be transported toward the printhead cleaning unit. If the conductivity subsequently deviates from the preset conductivity, the means for transporting the cleaning fluid can be switched off, for example, using the aforementioned method, or the valve can be switched to the first valve position.

[0024] The methods can be developed in the same way as the arrangement, in particular with the features of the dependent claims or corresponding method features. The technical advantages achieved by the methods correspond to those explained in connection with the arrangement according to the invention.

[0025] Examples of implementations are described below using drawings. They show: Figure 1 shows a schematic representation of a first arrangement for supplying a print head cleaning unit of an ink jet printing device with a cleaning fluid, and Figure 2 shows a schematic representation of a second arrangement for supplying a print head cleaning unit of an ink jet printing device with a cleaning fluid.

[0026] Figure 1shows a schematic representation of a first arrangement 100 for supplying a printhead cleaning unit of an inkjet printing device with a cleaning fluid. The arrangement 100 comprises a cleaning fluid reservoir 102 that stores a cleaning fluid 103, a supply line 104, a means 106 for determining a conductivity of the cleaning fluid 103, a means 108 for transporting the cleaning fluid 103, and a supply line 110.

[0027] The means 106 for determining the conductivity of the cleaning fluid 103 is, in particular, a conductivity sensor 106, with the aid of which the electrical conductivity of the cleaning fluid 103 can be determined. The sensor 106 is arranged on or in the supply line 104 such that the sensor 106 can determine the conductivity of the cleaning fluid 103 located in the supply line 104.

[0028] The means 108 for transporting the cleaning fluid 103 is in particular a pump 108. The pump 108 conveys in particular the cleaning fluid 103 through the feed line 104 and the supply line 110 and thus in the direction of the print head cleaning unit.

[0029] In particular, the sensor 106 determines the conductivity at at least one measuring point on or in the supply line 104.

[0030] The measuring point is arranged along the supply line 104, and the supply line 104 forms a first section 104a of the supply line 104 between the measuring point and the pump 108. The length of the first section 104a is dimensioned in particular such that it depends on a cross-sectional area (m2) of the first section 104a of the supply line 104, a flow rate (m3 / s) of the cleaning fluid 103 through the first section 104a generated by the pump 108, and a time (s) required for measuring the conductivity and controlling the pump 108. Thus, the pump 108 can be switched off as soon as a conductivity measurement result deviating from an expected conductivity is detected for a cleaning fluid 103 transported into the arrangement 200 for the first time. The pump 108 can be switched off without the cleaning fluid 103 having already been transported into the pump 108 or into the supply line 110.After shutting down the pump 108, for example, the supply line 104 containing the different cleaning fluid 103 can be easily replaced or cleaned. This prevents the different cleaning fluid 103 from further spreading or penetrating the assembly 100, the printhead cleaning unit, or a printhead.

[0031] The arrangement 100 can be controlled such that the cleaning fluid 103 is first pumped from the cleaning fluid reservoir 102 through the supply line 104 by means of the pump 108. The conductivity of the cleaning fluid 103 can then be determined using the sensor 106, and if the measured conductivity deviates from a preset conductivity, the pump 108 can be controlled so that it does not pump. If the measured conductivity corresponds to the preset conductivity or lies within a preset conductivity range, the pump 108 can be controlled so that it continues pumping.

[0032] This prevents cleaning fluid 103 that does not have the desired preset conductivity from entering the printhead cleaning unit and the printhead.

[0033] Figure 2shows a schematic representation of a second arrangement 200 for supplying a print head cleaning unit of an inkjet printing device with the cleaning fluid 103. Elements with the same structure or the same function have the same reference numerals.

[0034] In addition to the information already provided in connection with the Figure 1 In the arrangement 100 shown, the arrangement 200 comprises a valve 202 and a return line 204. With the help of the valve 202, the cleaning fluid 103 delivered by the pump 108 can be directed either into the supply line 110 or into the return line 204. The valve 202 can be connected to the pump 108 via a connecting line 206 or directly to the pump 108. The return line 204 is connected to the valve 202 and the cleaning fluid reservoir 102. The valve 202 can be, for example, a 3 / 2-way valve.

[0035] The valve 202, the return line 204, the cleaning fluid reservoir 102, the supply line 104, the pump 108, and the connecting line 206 form a cleaning fluid circuit. When the valve 202 is in a first valve position, the cleaning fluid 103 can circulate in the cleaning fluid circuit, in particular with the aid of the pump 108. The cleaning fluid 103 flows through the supply line 104 and past the sensor 106. The cleaning fluid 103 then flows through the pump 108, the connecting line 206, the valve 202, and the return line 204 back into the cleaning fluid reservoir 102.

[0036] In a second valve position of the valve 202, the connecting line 206 is connected to the supply line 110 and the cleaning fluid 103 can be transported from the cleaning fluid reservoir 102 by means of the pump 108 in the direction of the print head cleaning unit.

[0037] The arrangement 200 can be controlled such that, upon supplying new cleaning fluid 103, the valve 202 is initially in the first valve position, and the pump 108 pumps the cleaning fluid 103 through the cleaning fluid circuit. The conductivity of this cleaning fluid 103 can be determined. In particular, the pump 108 is controlled such that the cleaning fluid 103 is pumped through the cleaning fluid circuit for a specific period of time or until the sensor 106 has determined a stable conductivity measurement result. If the determined conductivity measurement result corresponds to the preset conductivity or lies within a preset conductivity range, the valve 202 can be moved to the second valve position. This pumps the cleaning fluid 103 to the print head cleaning unit.In the event that the conductivity measurement result deviates from the preset conductivity, the pump 108 can be stopped and the valve 202 remains in its initial valve position. This reliably prevents unwanted or unsuitable cleaning fluid 103 from being pumped to the print head cleaning unit.

[0038] Even if the valve 202 has already been set to the second valve position, the conductivity of the pumped cleaning fluid 103 can still be determined using the sensor 106 and compared with the preset conductivity value. If a deviation occurs, the pump 108 can then be stopped and / or the valve 202 can be returned to the first valve position.

[0039] In the event that a deviation in conductivity is detected, the affected elements, in particular the supply line 104, can then be cleaned or replaced. List of reference symbols

[0040] 100, 200 Arrangement for supplying a printhead cleaning unit with a cleaning fluid 102 Cleaning fluid reservoir 103 Cleaning fluid 104 Supply line 104a First section of the supply line 106 Means for determining the conductivity 108 Means for transporting the cleaning fluid 110 Supply line 202 Valve 204 Return line

Claims

1. Arrangement (100, 200) for supplying a print head cleaning unit of an ink jet printing device with a cleaning fluid (103), with a supply line (110) which can be connected at least to the print head cleaning unit and via which a cleaning fluid (103) can be supplied to the print head cleaning unit, with a means (108) for transporting the cleaning fluid (103) at least through the supply line (110), wherein the cleaning fluid (103) can be supplied to the means (108) for transporting via a supply line (104), and with a means (106) for determining the conductivity of the cleaning fluid (103) in the supply line (104).

2. The arrangement according to claim 1, wherein the means (106) for determining the conductivity is arranged at a measuring point along the supply line (104) and the supply line (104) forms a first section (104a) of the supply line (104) between the measuring point and the means (108) for transport.

3. The arrangement according to claim 2, wherein the first section (104a) of the supply line (104) is at least so long that the cleaning liquid (103) transported through the first section (104a) only reaches the means (108) for transport when a conductivity measurement result is available.

4. The arrangement according to one of the preceding claims, wherein the arrangement further comprises a cleaning liquid reservoir (102) and the supply line (104) is connected to the cleaning liquid reservoir (102).

5. The arrangement according to claim 4, wherein the arrangement further comprises a return line (204) and at least the return line (204), the cleaning liquid reservoir (102), the means (108) for transporting the cleaning liquid (103) and the supply line (104) with the means (106) for determining the conductivity form a cleaning liquid circuit.

6. The arrangement according to claim 5, wherein a control unit of the arrangement in a measuring operating mode controls at least the means (108) for transporting the cleaning liquid (103) for transporting the cleaning liquid (103) through the cleaning liquid circuit.

7. The arrangement according to claim 6, wherein the control unit of the arrangement, in a cleaning operating mode, controls at least the means (108) for transporting the cleaning liquid (103) for transporting the cleaning liquid (103) to the printhead cleaning unit.

8. The arrangement according to one of the preceding claims 5 to 7, wherein the arrangement comprises a valve (202) which, in a first valve position, connects the means (108) for transporting the cleaning liquid (103) and the return line (204) so ​​that the cleaning liquid (103) can be transported through the cleaning liquid circuit and, in a second valve position, connects the means (108) for transporting the cleaning liquid (103) to the supply line (110) so that the cleaning liquid (103) can be fed to the supply line (110).

9. Method for controlling an arrangement according to one of the preceding claims, in which the cleaning liquid (103) is transported at least through one supply line (104) with the aid of the means (108) for transport, in which the conductivity of the cleaning liquid (103) in the supply line (104) is determined with the aid of a means (106) for determining the conductivity of the cleaning liquid (103), and in which the means (108) for transporting the cleaning liquid (103) is switched off if the determined conductivity of the cleaning liquid (103) deviates from a preset conductivity value.

10. A method for controlling an arrangement according to claim 8, in which the cleaning liquid is transported through the cleaning liquid circuit with the aid of the means (108) for transport, in which the conductivity of the cleaning liquid (103) in the supply line (104) is determined with the aid of a means (106) for determining the conductivity of the cleaning liquid (103), and in which a valve (202) is switched to a second valve position in which the means (108) for transporting the cleaning liquid (103) is connected to a supply line (110) when the determined conductivity of the cleaning liquid (103) is within a preset conductivity value.

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