Printing device for printing a printing substrate and control method

Abstract

A device (1) for printing on a printing substrate is provided. The device (1) comprises a printhead (2) for printing on a printing substrate with a printing medium, a container (3) for receiving the printing medium, a first sensor (7), a second sensor (8), a feed unit (4) for conveying the printing medium, and a control unit. The container (3) is fluidically connected to an inlet (9) and an outlet (10) of the printhead (2), so that printing medium can flow from the container (3) through the printhead (2) and into the container (3). The first sensor (7) is configured to detect a property of the printing medium when printing medium flows from the container (3) to the printhead (2), and the second sensor (8) is configured to detect a property of the printing medium when printing medium flows from the printhead (2) to the container (3).The conveying unit (4) is arranged fluidically between the container (3) and the printhead (2), wherein pressure medium can flow from the container (3) through the conveying unit (4) to the printhead (2), or wherein pressure medium can flow from the printhead (2) through the conveying unit (4) to the container (3). The control unit is configured to control the conveying unit (4) based on the properties detected by the first sensor (7) and / or the second sensor (8). Furthermore, a method for controlling a device (1) for printing on a print substrate is provided (Fig. 2).

Description

[0001] The invention relates to a device for printing on a printing substrate. The invention also relates to a method for controlling such a device. background

[0002] Inkjet printers are frequently used to print onto a substrate with a printing medium, such as ink. These printers can print using either drop-on-demand or continuous jet printing. In drop-on-demand printing, individual droplets are selectively ejected from a printhead. For example, in a bubble jet process, a heating element generates a vapor bubble, the pressure of which forces the droplet out of the printhead nozzle. Alternatively, a piezoelectric element can generate pressure that forces a droplet out of the printhead nozzle.

[0003] To achieve good print quality, precise control of the ink flow rate to and through the printhead is essential. Furthermore, precise control of the ink meniscus pressure within the printhead, nozzle, or nozzle line can be desirable to prevent, for example, unwanted ink leakage from the printhead.

[0004] With known devices and methods, the flow rate, the pressure at the inlet and outlet of the printhead, and / or the meniscus pressure are often difficult to control and / or regulate. Frequently, the fill level in a tank fluidically connected to the printhead, from which the printing medium can be supplied to the printhead, is measured in order to determine a hydrostatic pressure based on the fill level, the height of the tank, and other factors. Such determination of the flow rate and pressures is comparatively difficult and inaccurate, since, on the one hand, inaccurate level sensors can lead to comparatively high measurement inaccuracies, and on the other hand, the pipe routing can also have an influence. Consequently, the control and / or regulation of the flow rate, the pressure at the inlet and outlet of the printhead, and / or the meniscus pressure is comparatively inaccurate.

[0005] A device is known from EP 2 769 847 A2. In this device, a pressure sensor and a temperature sensor are provided in a supply line, through which pressure medium is supplied to a printhead, and in a return line, through which pressure medium is discharged from the printhead.

[0006] The sensors are integrated into a flow-through sensor block. The printing fluid is drawn from a tank and circulated by a pump through a heating element, heated, passed through the sensor block in front of the printhead, and then supplied to the printhead. Any printing fluid not expelled through the printhead nozzle is routed by the printhead through the sensor block and back into the tank. The circulation pump is fluidically positioned between the tank and the heating element. The sensors detect blockages, such as in a filter or line. If overpressure occurs on the pressure side of the circulation pump, for example, due to a blocked filter or other obstruction in one of the lines or in the printhead, printing fluid is diverted back to the circulation tank via a bypass line. In this case, the pressure measured by the sensors drops below a minimum threshold, triggering an alarm signal that is sent to a control system.Operations will be shut down until the overpressure incident is resolved.

[0007] Even this well-known device cannot control and / or regulate the flow rate, the pressure at the inlet and outlet of the printhead, and / or the meniscus pressure accurately enough. Summary

[0008] It is therefore an object of the present invention to provide a device for printing on a printing substrate and a method for controlling such a device that overcome these disadvantages. The device and method according to the invention enable precise control and / or regulation of a delivery rate and / or flow rate to and / or through the printhead.

[0009] This problem is solved by a device having the features of claim 1, and a method having the features of claim 11. The dependent claims relate to advantageous embodiments.

[0010] According to one aspect, a device for printing on a substrate is provided, wherein the device comprises a printhead for printing on the substrate with a printing medium and a container for receiving the printing medium. The container is fluidically connected to an inlet of the printhead and fluidically to an outlet of the printhead, such that printing medium can flow from the container through the printhead into the container. The device includes a first sensor and a second sensor, wherein the first sensor is configured to detect a property of the printing medium when printing medium flows from the container to the printhead, and the second sensor is configured to detect a property of the printing medium when printing medium flows from the printhead to the container.The device includes a conveying unit for conveying pressure medium, wherein the conveying unit is fluidically arranged between the reservoir and the printhead, wherein pressure medium can flow from the reservoir through the conveying unit to the printhead, or wherein pressure medium can flow from the printhead through the conveying unit to the reservoir. The device includes a control unit configured to control the conveying unit based on the characteristics detected by the first sensor and / or the second sensor.

[0011] According to another aspect, a method for controlling a device for printing on a printing substrate is created, comprising the following steps: detecting a property of a pressure medium flowing from a container of the device to a printhead of the device with a first sensor; detecting a property of a pressure medium flowing from the printhead to the container of the device with a second sensor; controlling, based on the properties of the pressure medium detected by the first and the second sensors, a conveying unit of the device, wherein the conveying unit sets a conveying pressure and / or a conveying quantity of the pressure medium based on the properties detected by the first and the second sensors.

[0012] The delivery unit can be or include a pump. The control unit can be configured to control and / or regulate the delivery rate and / or delivery pressure of the delivery unit based on the characteristics detected by the first and / or second sensor.

[0013] Because the delivery unit can be controlled and / or regulated, the flow rate or delivery volume of pressure medium to the printhead, and / or through the printhead, can be set, controlled and / or regulated with high accuracy.

[0014] The device may include a mixing unit that is fluidically connected to the pumping unit, for example, it may be located upstream of the pumping unit. The mixing unit may contain or be supplied with hydraulic fluid. For example, the mixing unit may be connected to a refill reservoir. The pumping unit may be configured to pump hydraulic fluid from the mixing unit and / or the refill reservoir and / or feed it into the circuit. This eliminates the need for a separate and / or additional refill pump.

[0015] Since the first sensor can detect a property of the fluid flowing from the reservoir to the printhead, and the second sensor can detect a property of the fluid flowing from the printhead to the reservoir, the delivery unit can be controlled in such a way that a predetermined pressure can be achieved with high accuracy upstream and / or downstream of the printhead, and / or can be adjusted, controlled, and / or regulated with correspondingly high accuracy. In some embodiments, the meniscus pressure of the printhead can be precisely set and / or controlled. The delivery rate can be determined accordingly simply and easily from the properties detected by the first and second sensors, for example, based on the pressures of the printing medium measured by the sensors.

[0016] The first sensor can be located outside the container. The second sensor can also be located outside the container. This can result in higher measurement accuracy compared to sensors located inside the container.

[0017] The device can be or include a printer. For example, the device can be or include an inkjet printer, e.g., a bubble jet printer and / or a piezo printer, and / or an inkjet printer. The printing medium can be liquid. The printing medium can be, for example, ink.

[0018] The property of the pressure medium detected by the first sensor can be a state variable of the pressure medium. The property of the pressure medium detected by the second sensor can also be a state variable of the pressure medium. This state variable and / or property can, for example, be or include temperature. This state variable and / or property can, for example, be or include pressure.

[0019] The conveying unit can be controlled in such a way that a conveying quantity and / or a conveying pressure of the conveying unit can be controlled.

[0020] The conveying unit can be fluidically positioned upstream of the first sensor. The conveying unit can be fluidically positioned downstream of the second sensor.

[0021] The device can include a second delivery unit, preferably a pump. In some embodiments, the delivery unit can be arranged such that pressure medium can flow from the reservoir through the delivery unit to the printhead, and the second delivery unit can be arranged such that pressure medium can flow from the printhead through the delivery unit to the reservoir. It is possible for the second delivery unit to be arranged fluidically downstream of the second sensor.

[0022] The device may include a pressure setting unit, which may be configured to set a pressure in the container. The pressure may be the container pressure.

[0023] The pressure setting unit can be controlled in such a way that the pressure set by the pressure setting unit in the container can be controlled.

[0024] The pressure adjustment unit can be fluidically connected to the container. The pressure adjustment unit can be configured to exert pressure, preferably the container pressure, on pressure medium contained in the container. In some embodiments, the pressure adjustment unit can be arranged above the container.

[0025] The pressure control unit can be or include a proportional valve and / or a gas pump. It can be provided that the pressure control unit is connected to a pressure relief line and a vacuum line. In some embodiments, the pressure control unit can adjust the pressure, e.g., the tank pressure, via a corresponding valve opening and / or valve position. In a first valve position, the pressure can correspond to the pressure specified by the pressure relief line. In a second valve position, the pressure can correspond to the pressure specified by the vacuum line. Depending on the valve position, a selected pressure between these two extreme values ​​can be set. The valve can be continuously adjustable. In some embodiments, the pressure specified by the pressure relief line can range from 0 to 6 bar.In some embodiments, the pressure applied by the vacuum line can be or include a vacuum pressure. For example, the vacuum pressure, relative to a reference external pressure, such as ambient pressure, can be 0 to -1 bar. Vacuum pressure can refer to a pressure lower than the reference pressure, ambient pressure, or standard pressure, e.g., lower than 1 bar. Gauge pressure can refer to a pressure higher than the reference pressure, ambient pressure, or standard pressure, e.g., higher than 0.5 bar or higher than 1 bar. Vacuum pressure can also refer to a vacuum.

[0026] It may be provided that the pressure setting unit can be controlled and / or regulated depending on and / or based on the properties detected by the first sensor and / or the second sensor.

[0027] It may be provided that a fluid, for example a gas and / or a gas mixture, can be introduced into the container from, through or with the pressure control unit, so that, due to the pressure of the fluid introduced into the container, e.g. due to a gas pressure, a pressure, e.g. a container pressure, can be established in the container, and / or the fluid, e.g. the gas and / or gas mixture, can exert a pressure on the pressure medium contained in the container.

[0028] The container can be fluidically connected to the printhead via a supply line. The container can be fluidically connected to the inlet and / or outlet of the printhead via a supply line.

[0029] The first sensor can be located on, near, or in a supply line between the reservoir and the printhead. It can be arranged on, near, and / or above the printhead. The first sensor can be located on, near, and / or above the printhead inlet. In some embodiments, the first sensor can be located as close as possible to the printhead and / or its inlet.

[0030] The second sensor can be located on, near, or in a return line between the container and the printhead. It can also be positioned on, near, and / or above the printhead. The second sensor can be located on, near, and / or above the printhead outlet. In some embodiments, the second sensor can be positioned as close as possible to the printhead and / or its outlet. This allows for accurate determination of the flow rate of printing material into and / or through the printhead.

[0031] The control unit can be configured to control the feed unit such that the printhead meniscus pressure is between -50 mbar and 500 mbar, for example, between -50 mbar and 250 mbar, and / or between 5 mbar and 250 mbar. The feed unit can be controlled such that the printhead meniscus pressure can be set and / or controlled, for example, between -50 mbar and 500 mbar, or between -50 mbar and 250 mbar, and / or between 20 mbar and 250 mbar. The meniscus pressure can be defined and / or measured on the underside of the printhead. The meniscus pressure can correspond to a vacuum on the underside of the printhead, for example, in a nozzle channel of the printhead.

[0032] In some embodiments, the control unit can alternatively or additionally be configured to control the second feed unit and / or the pressure setting unit such that the printhead meniscus pressure is between -50 mbar and 500 mbar, for example, between -40 mbar and 500 mbar. The second feed unit and / or the pressure setting unit can alternatively or additionally be controlled such that the printhead meniscus pressure can be set and / or controlled, for example, between -50 mbar and 500 mbar, for example, between -40 mbar and 500 mbar.

[0033] The pressure in the container can be positive pressure. The pressure in the container can be negative pressure.

[0034] The first sensor can be a pressure sensor. Alternatively or additionally, the first sensor can be a temperature sensor. The property detected by the first sensor can be or include the pressure and / or temperature of the pressure medium. The second sensor can be a pressure sensor. Alternatively or additionally, the second sensor can be a temperature sensor. The property detected by the second sensor can be or include the pressure and / or temperature of the pressure medium.

[0035] The first and second sensors can be configured to detect the pressure of the pressure medium. The control unit can be configured to determine the pressure difference between the pressures detected by the first and second sensors and to control the conveying unit based on this pressure difference. Alternatively or additionally, the control unit can be configured to determine an average of the pressures detected by the first and second sensors and to control the conveying unit based on this average. It can be provided that the second conveying unit is controlled based on the pressure detected by the first and / or second sensor, for example, based on the average and / or the pressure difference. In some embodiments, it can be provided, alternatively or additionally, that the pressure setting unit is controlled based on the pressure detected by the first and / or second sensor.

[0036] In some embodiments, the first and second sensors may be configured to detect the temperature of the pressure medium. The control unit may be configured to detect temperature deviations from a setpoint. The device may include a temperature control unit. The temperature control unit may, for example, be a heating unit and / or a cooling unit. The temperature may be regulated within the setpoint range. The control unit may control and / or regulate the temperature control unit. In some embodiments, the temperature control unit may be configured to set the temperature of the pressure medium and / or to heat and / or cool the pressure medium. The temperature control unit may be located inside the container. Description of exemplary implementations

[0037] The following section explains an exemplary embodiment in more detail with reference to figures in a drawing. This shows: Fig. 1 a schematic representation of a device according to the invention; Fig. 2 a schematic representation of another device according to the invention; Fig. 3 a schematic representation of yet another device according to the invention; and Fig. 4 a schematic representation of yet another device according to the invention.

[0038] The Figs. 1 to 4 Figure 1 shows schematic representations of various embodiments of a device 1 according to the invention. The device 1 has a printhead 2. The printhead 2 can be used to print printing medium onto or into a printing substrate. The printhead 2 can have one or more nozzles from which printing medium, for example ink, can be or will be ejected.

[0039] The device 1 can be or comprise a printer, e.g., an inkjet printer. The printing substrate can be or comprise a substrate to be printed, a surface to be printed, a body to be printed, and / or the like. The printing substrate can be, for example, paper, cardboard, or the like. The printing substrate can be or comprise a laminate and / or a plastic object. However, the printing substrate is not limited to these examples. "Printing" can mean that printing media can be printed onto the printing substrate and / or that printing media can be printed into the printing substrate.

[0040] The printhead 2 may be configured to print the substrate using a piezoelectric method. In some embodiments, the substrate may be printed using drop-on-demand technology. Alternatively or additionally, other printing methods, such as bubble jet printing, are also possible. The device 1 and / or the printhead 2 may be a piezoelectric inkjet printer, or a component thereof. In some embodiments, the device 1 and / or the printhead 2 may alternatively or additionally be a mechanical inkjet printer, or a component thereof.

[0041] The device 1 comprises a container 3. The container 3 can be configured to receive, store, and / or hold pressure medium. The container 3 is fluidically connected to the printhead 2, allowing pressure medium to flow from the container 3 into the printhead 2. For example, the container 3 can be fluidically connected to an inlet 9 of the printhead 2. The container 3 can also be fluidically connected to the printhead 2 via a supply line 11.

[0042] Container 3 is fluidically connected to printhead 2 such that pressure medium can flow from printhead 2 to or into container 3. For example, an outlet 10 of printhead 2 can be fluidically connected to container 3. Printhead 2 can also be fluidically connected to container 3 via a return line 12.

[0043] Container 3 can have a volume between 10 ml and 100 ml, preferably between 10 ml and 50 ml. Container 3 can have a volume less than 50 ml.

[0044] It may be provided that the container 3 can be contained and / or formed within a container unit 16. It may be provided that the container unit 16 is designed in such a way that it can form a container 3.

[0045] It may be provided that container 3 is or can be a pressurized container, and / or can have an overpressure.

[0046] Alternatively, it may be provided that container 3 is or can be a vacuum container, and / or can have a negative pressure and / or a vacuum.

[0047] Container 3 can be positioned above and / or located above printhead 2. Container 3 can, for example, be positioned in a plane that is vertically and / or perpendicularly spaced from a plane in which printhead 2 may be positioned. Container 3 can be positioned at a height above the height at which printhead 2 is positioned.

[0048] It may be provided that the height above printhead 2 can be determined, defined, and / or measured in the direction of gravity. The height can correspond to a geodetic height above printhead 2. This means the height difference between the liquid level of the ink in the reservoir and the printhead. Alternatively, the height can correspond to the height difference between the outlet of the ink reservoir and the inlet of the printhead, measured in the direction of gravity.

[0049] The distance between a column of liquid pressure medium in the container 3 and the underside of the printhead 2 can be between -1000 mm and 1000 mm, preferably between 150 mm and 500 mm. The liquid column can be or represent a fill height and / or fill level of pressure medium in the container 3. Alternatively or additionally, the liquid column can include pressure medium that may be present in the line 11 connecting the container 3 to the printhead 2.

[0050] The distance of the liquid column can be defined, determined, and / or measured from a surface of the liquid column, e.g., the surface of the pressure medium in the container 3, to the underside of the printhead 2. Alternatively or additionally, the distance of the liquid column can be defined, determined, and / or measured from the underside of the container 3 to the underside of the printhead 2.

[0051] In some embodiments, the distance can be defined, determined, and / or measured in the direction of gravity. Alternatively or additionally, in some embodiments, the distance can comprise a length of one of the lines 11, 12.

[0052] The distance can be set or adjusted in such a way that a required pressure range, for example a meniscus pressure, can be set or adjusted.

[0053] In some embodiments, for example, a refilling mechanism may be provided or implemented to control and / or regulate the distance, fill level and / or fill height.

[0054] The supply line 11 and / or the return line 12 can each be or comprise a hose. For example, the hose can be made of a plastic and / or plastic material. The supply line 11 and / or the return line 12, and / or the hose, can be coated. The coating can, for example, be or comprise an ETFE coating. An ETFE coating can be provided, for example, if the printing medium is a solvent-based ink and / or if the printing medium is a UV ink. In some embodiments, the inner diameter of the respective line 11, 12, and / or the hose can be between 2 mm and 6 mm, preferably between 5 mm and 6 mm. In some embodiments, the outer diameter of the respective line 11, 12, and / or the hose can be between 4 mm and 10 mm, preferably between 8 mm and 10 mm.

[0055] It may be provided that a shut-off valve is arranged in the supply line 11 and / or the return line 12, and / or that the supply line 11 and / or the return line 12 has a shut-off valve. The shut-off valve may be configured to prevent and / or block the flow of hydraulic fluid through the respective line 11, 12. This prevents and / or blocks the flow of hydraulic fluid from the reservoir 3 to the printhead 2, and / or from the printhead 2 to the reservoir 3, when the device 1 and / or the method is, for example, in a standstill state. With the flow of hydraulic fluid blocked, refilling of hydraulic fluid and / or pressure regulation in the reservoir 3 may be facilitated, or alternatively, or additionally. Furthermore, leakage of ink through the printhead in the standstill state may be prevented.

[0056] To print on a substrate, printing medium from reservoir 3 can be supplied to printhead 2. At least a portion of the supplied printing medium can be ejected through nozzles of printhead 2 to print on the substrate. The portion of the printing medium that is not ejected can be returned from printhead 2 to reservoir 3.

[0057] The printing medium can be a liquid or contain ink. For example, the printing medium can be ink or contain solvents.

[0058] Container 3 can supply the printing medium, e.g., ink. Excess and / or excessively supplied printing medium may be returned to container 3 by printhead 2.

[0059] To achieve good print quality, precise adjustment of the meniscus pressure of printhead 2 may be necessary. Meniscus pressure can refer to a vacuum on the underside of printhead 2 within a nozzle and / or nozzle channel. This pressure can retain printing medium, such as ink, thus preventing leakage from the printhead.

[0060] For example, in a drop-on-demand procedure, it may be provided that pressure medium is retained between the intended ejection of droplets to prevent unintentional release of pressure medium from the nozzle. Alternatively or additionally, it may be provided that the meniscus pressure is used to tension the surface of the pressure medium in the nozzle and / or nozzle channel after the release or ejection of a droplet in order to prevent or at least reduce the escape of satellite droplets after release or launch.

[0061] In some embodiments, the meniscus pressure can be precisely set, controlled, and / or regulated. This can improve print quality. In some embodiments, the meniscus pressure can be set, controlled, or regulated between -50 and 500 mbar, for example, between -50 mbar and 250 mbar. In some embodiments, deviations of ±5 mbar or less can be achieved.

[0062] The device 1 comprises a first sensor 7 and a second sensor 8. The first sensor 7 is configured to detect a property of the pressure medium as it flows from the reservoir 3 to the printhead 2, for example, through the supply line 11. The second sensor 8 is configured to detect a property of the pressure medium as it flows from the printhead 2 to the reservoir 3, for example, through the return line 12. The property of the pressure medium can be a state variable of the pressure medium. The property and / or state variable of the pressure medium can be a pressure and / or a temperature of the pressure medium. The first sensor 7 can be arranged on, at, or within the supply line 11, through which the pressure medium can flow from the reservoir 3 to the printhead 2.It may be provided that the second sensor 8 can be arranged on, at or in the return line 12, through which pressure medium can flow from the printhead 2 to the container 3.

[0063] The first sensor 7 can be or comprise a pressure sensor and / or a temperature sensor. The second sensor 8 can be or comprise a pressure sensor and / or a temperature sensor. In some embodiments, the first sensor 7 and / or the second sensor 8 can be or comprise a combined pressure and temperature sensor and / or be configured to detect both the temperature and pressure of the pressure medium.

[0064] The first sensor 7 and / or the second sensor 8 may be arranged on or near the printhead 2. In some embodiments, the first sensor 7 and / or the second sensor 8 may be arranged close to the printhead 2. In some embodiments, the first sensor 7 may be arranged on and / or at, or at least near, the inlet 9 of the printhead 2. In some embodiments, the second sensor 8 may be arranged on and / or at, or at least near, the outlet 10 of the printhead 2. The property detected by the first sensor 7 may correspond to the corresponding local value of the pressure medium at the inlet 9 of the printhead 2. The property detected by the second sensor 8 may correspond to the corresponding local value of the pressure medium at the outlet 10 of the printhead 2.

[0065] For example, if the first sensor 7 is located close to the inlet 9, a measured pressure may correspond to the pressure of the pressure medium at or in the inlet 9. Similarly, if the second sensor 8 is located close to the outlet 10, a measured pressure may correspond to the pressure of the pressure medium at or in the outlet 10.

[0066] The device 1 includes a pumping unit 4. The pumping unit 4 can be or include a pump, e.g., a micro gear pump. The pumping unit 4 can be configured to pump hydraulic fluid from the reservoir 3 to the printhead 2 and / or from the printhead 2 into the reservoir. The pumping unit 4 is fluidically arranged between the reservoir 3 and the printhead 2. The pumping unit 4 and / or the micro gear pump can be low-vibration and / or essentially pulse-free during flow.

[0067] For example, in the Figure 1 and 2As shown, the pumping unit 4 can be arranged fluidically between the reservoir 3 and the printhead 2 such that pressure medium can flow from the reservoir 3 through the pumping unit 4 to and / or into the printhead 2. The pumping unit 4 can also be arranged fluidically upstream of the first sensor 7. In some embodiments, the pumping unit 4 and / or the first sensor 7 can be arranged on, in, or near the supply line 11. In In some embodiments, the first sensor 7 can be arranged on, in or near the inlet 9 of the printhead 2.

[0068] For example, in the Figures 3 and 4 As shown, the pumping unit 4 can be arranged fluidically between container 3 and printhead 2 such that pressure medium can flow from the printhead 2 to and / or into the container 3. It is also possible for the pumping unit 4 to be arranged fluidically downstream of the second sensor 8. InIn some embodiments, the conveying unit 4 and / or the second sensor 8 can be arranged on, in, or near the return line 12. In some embodiments, the second sensor 8 can be arranged on, in, or near the outlet 10 of the printhead 2.

[0069] In some embodiments, a second conveying unit 6 may be provided. In some embodiments, the second conveying unit 6 may be arranged fluidically between the printhead 2 and the container 3, e.g., at, in, or near the return line 12 and / or the outlet 10, if the conveying unit 4 may be arranged fluidically between the container 3 and the printhead 2, see e.g.: Fig. 1In some embodiments, the second pumping unit 6 can be arranged fluidically between the reservoir 3 and the printhead 2, e.g., at, in, or near the supply line 11 and / or the inlet 9, provided that the pumping unit 4 can be arranged fluidically between the printhead 2 and the reservoir 3. The second pumping unit 6 can be or include a pump, for example, a micro gear pump. The second pumping unit 6 and / or the micro gear pump can be low-vibration and / or essentially pulse-free during flow.

[0070] It may be provided that the pumping unit 4 and / or the second pumping unit 6 are configured to pump pressurised medium from the reservoir 3 to the printhead 2. The pumping unit 4 and / or the second pumping unit 6 can set a corresponding pumping pressure and / or flow rate. The pumping pressure and flow rate can be selected, controlled and / or regulated such that the properties detected by the first sensor 7 and / or the second sensor 8 and / or the meniscus pressure have predetermined values, or at least do not deviate significantly from them.

[0071] It may be provided that the pumping unit 4 and / or the second pumping unit 6 are configured to pump pressure medium from the printhead 2 to the container 3. The pumping unit 4 and / or the second pumping unit 6 can set a corresponding pumping pressure and / or flow rate. The pumping pressure and flow rate can be selected, controlled, and / or regulated such that the properties detected by the first sensor 7 and / or the second sensor 8 and / or the meniscus pressure have predetermined values, or at least do not deviate significantly from them.

[0072] In some embodiments, it may be provided that the conveying direction of conveying unit 4 and / or the second conveying unit 6 can be changed, varied, controlled and / or regulated, as e.g. in Fig. 4As indicated by example, the conveying direction may be set depending on the container pressure and / or the arrangement and / or position of the conveying unit 4 and / or the second conveying unit 6. In some embodiments, the conveying direction may be selected depending on whether the container pressure is positive or negative, e.g., a vacuum.

[0073] The device 1 can include a pressure setting unit 5. The pressure setting unit 5 can be configured to set a pressure in the container 3.

[0074] In some embodiments, the pressure setting unit 5 may be or include a proportional valve. For example, the pressure setting unit 5 may be equipped with a (not in Figure 1 (shown) overpressure line and / or a (not in Figure 1 The vacuum line shown is or will be fluidically connected.

[0075] In some embodiments, the pressure setting unit 5 can adjust the tank pressure depending on the valve position. In a first valve position, the tank pressure can correspond to the pressure supplied by the overpressure line. In a second valve position, the tank pressure can correspond to the pressure supplied by the underpressure line. Depending on the valve position between the first and second valve positions, the tank pressure can lie between these pressures. It may be provided that the tank pressure can be set, controlled, regulated, and / or selected by controlling the respective valve position and / or the first pressure setting unit 5.

[0076] In some embodiments, the pressure relief line can provide a pressure of 0 to 6 bar. In some embodiments, the vacuum relief line can provide a pressure of 0 to -1 bar.

[0077] Alternatively or additionally, the pressure setting unit 5 can be or include a gas pump. A suitable gas pump can be configured to adjust, control, or regulate the container pressure accordingly.

[0078] It may be provided that a fluid, for example a gas and / or a gas mixture, can be introduced into the container 3 from, through or with the pressure setting unit 5, so that the container pressure in the container 3 can be adjusted due to the pressure of the fluid introduced into the container 3, e.g. due to a gas pressure, and / or the fluid, e.g. the gas and / or gas mixture, can exert a pressure on the pressure medium contained in the container 3.

[0079] The pressure in container 3 can be or be a gas pressure. This pressure can act on any pressure medium stored and / or absorbed in container 3.

[0080] The pressure setting unit 5 can be located outside the container 3. The pressure setting unit 5 can be located above the container 3. For example, the pressure setting unit 5 can be located at a height above the height of the container 3. The pressure setting unit 5 can be fluidically connected to the container 3 via a line 14.

[0081] The device 1 includes a control unit (not shown in the figures). The control unit can be connected to the first sensor 7 and / or the second sensor 8, and / or receive values ​​detected by the first sensor 7 and / or the second sensor 8. The control unit can be connected to the conveying unit 4 to control and / or regulate it. In some embodiments, the control unit can be connected to the second conveying unit 6 and / or the pressure setting unit 5 to control and / or regulate them.

[0082] The control unit can be or include a microcontroller. The control unit can include an FPGA, an integrated circuit, a logic circuit, a computer unit, and / or a microprocessor.

[0083] The device 1 and / or the method may comprise an operating state and a rest state. The rest state may be a standby state. The device 1 and / or the method may be switched off in the rest state.

[0084] It may be provided that the control and / or regulation of the conveying unit 4 and / or the second conveying unit 6, and / or the measurement of the pressure of the pressure medium, can take place, preferably continuously, when the device 1 and / or the method is in the operating state. It may be provided that the control and / or regulation of the conveying unit 4 and / or the second conveying unit 5, and / or the measurement of the pressure of the pressure medium, does not take place when the device 1 and / or the method is at rest.

[0085] It may be provided that, in the resting state, no printing medium can flow through and / or circulate between the reservoir 3 and the printhead 2. For example, if a filter is arranged in the supply line 11 and / or the return line 12, this can prevent or at least reduce dilution of the printing medium.

[0086] InIn some embodiments, the first sensor 7 and the second sensor 8 may each detect a pressure of the pressure medium. The control unit may be configured to calculate an average value and / or a pressure differential from the pressures detected by the first sensor 7 and the second sensor 8. Based on the calculated average value and / or pressure differential, the control unit may be configured to control and / or regulate the conveying unit 4, the second conveying unit 6, and / or the pressure setting unit 5. Alternatively or additionally, in some embodiments, the control unit may be able to control and / or regulate the conveying unit 4, the second conveying unit 6, and / or the pressure setting unit 5 based on the pressure detected by the first sensor 7 and / or the second sensor 8.

[0087] It may be provided that the tank pressure and / or the pressure setting unit 5 can be controlled and / or regulated in such a way that, in conjunction with the control and / or regulation of the pumping unit 4 and / or the second pumping unit 6, and / or the pumping pressure and / or the pumping rate of the pumping unit 4 and / or the second pumping unit 6, a predetermined meniscus pressure, flow rate and / or pumping rate to or through the pressure head 2 can be set. It may also be provided that the tank pressure and / or the pressure setting unit 5 can be controlled and / or regulated in such a way that the properties detected by the first sensor 7 and / or the second sensor 8 can have predetermined values ​​and / or be within a tolerance range.

[0088] The pressure difference can, for example, correspond to a pressure difference between inlet 9 and outlet 10 of the printhead 2. The pressure difference can thus determine and / or represent the flow rate of the printing medium through the printhead 2.

[0089] The mean pressure can, for example, correspond to, and / or approximate and / or represent the meniscus pressure.

[0090] Alternatively or additionally, the control unit may be able to control and / or regulate the conveying unit 4, and / or the second conveying unit 6, and / or the pressure setting unit 5, based on the temperature detected by the first sensor 7 and / or the second sensor 8. In some embodiments, an average and / or a difference of the temperature detected by the first sensor 7 and / or the second sensor 8 may be calculated, and based on the average and / or the difference, and / or based on an absolute value of one or both temperature values, a temperature control unit of the device 1, for example, a heating unit and / or a cooling unit of the temperature control unit, may be controlled and / or regulated.

[0091] In some embodiments, the first sensor 7 and / or the second sensor 8 can be configured to detect and / or measure the pressure of the pressure medium with an accuracy of ± 2 mbar or less. In some embodiments, the first sensor 7 and / or the second sensor 8 can be configured to detect and / or measure the temperature of the pressure medium with an accuracy of ± 1 K or less.

[0092] In some embodiments, the device 1 may include a temperature control unit (not shown in the figures). The temperature control unit may be or include a heating unit and / or a cooling unit. The temperature control unit may be configured to heat and / or cool hydraulic fluid, bring it to a predetermined temperature, and / or provide hydraulic fluid at a predetermined temperature. The control unit may be connected to the temperature control unit and control and / or regulate it. The control unit may be able to set or specify the predetermined temperature. In some embodiments, the control unit may control and / or regulate the temperature control unit such that a temperature detected by the first sensor 7 and / or the second sensor 8 may deviate by less than ± 1 K from a temperature setpoint.

[0093] The temperature control unit, and / or a heating unit and / or a cooling unit, can be arranged on, in or near the container 3.

[0094] The heating unit can comprise one or more heating mats arranged in container 3. The heating unit can comprise one or more heating coils or heating filaments.

[0095] The cooling unit may include water cooling. In some embodiments, the cooling unit, and / or the water cooling system, may have a proportional valve, which may be located, for example, at or near an inlet to the container 3, such as an inlet in the area of ​​a recirculation line or the return line 12. The proportional valve may control and / or regulate the flow rate of cooling water, thus controlling and / or regulating the cooling process.

[0096] It may be provided that, depending on the properties detected by the first sensor 7 and / or the second sensor 8, e.g. pressure and / or temperature, the delivery pressure and / or the delivery rate of the delivery unit 4, and / or the second delivery unit 6, can be set, controlled, regulated and / or selected. In In some embodiments, the container pressure can be set, controlled, regulated, and / or selected depending on the properties detected by the first sensor 7 and / or the second sensor 8, e.g., pressure and / or temperature. It can also be provided that, depending on the properties detected by the first sensor 7 and / or the second sensor 8, e.g., pressure and / or temperature, the conveying unit 4, and / or the second conveying unit 6, and / or the pressure setting unit 5, can be set, controlled, regulated, and / or selected.

[0097] It may be provided that by controlling and / or regulating the conveying unit 4, and / or the second conveying unit 6 and / or the pressure setting unit 5, and / or the conveying pressure, conveying quantity and / or container pressure, the meniscus pressure of the printhead 2 can be controlled and / or regulated.

[0098] It may be provided that the meniscus pressure can be controlled and / or regulated with a deviation of less than ± 5 mbar, e.g., compared to a predetermined and / or adjustable meniscus pressure. For example, the meniscus pressure can be controlled and / or regulated with a deviation of less than ± 5 mbar by the conveying unit 4, and / or the second conveying unit 6, and / or the pressure setting unit 5, and / or the conveying pressure, the conveying rate, and / or the tank pressure, e.g., compared to a predetermined and / or adjustable meniscus pressure.

[0099] It may be provided that the pressure differential can be controlled and / or regulated with a deviation of less than ± 5 mbar, e.g., compared to a predetermined and / or adjustable pressure differential. For example, the pressure differential can be controlled and / or regulated with a deviation of less than ± 5 mbar by the conveying unit 4, and / or the second conveying unit 6, and / or the pressure setting unit 5, and / or by the conveying pressure, conveying rate, and / or the tank pressure, e.g., compared to a predetermined and / or adjustable pressure differential.

[0100] InIn some embodiments, the device 1 may have a third sensor 20. The third sensor 20 may, for example, be a velocity sensor capable of detecting the flow velocity of the hydraulic fluid. Alternatively or additionally, the third sensor 20 may, for example, be a flow sensor capable of detecting the volumetric flow rate of the hydraulic fluid. Alternatively or additionally, the third sensor 20 may be a viscosity sensor and / or detect the viscosity of the hydraulic fluid. Alternatively or additionally, the third sensor 20 may be a temperature sensor and / or detect the temperature of the hydraulic fluid. The control unit may be connected to the third sensor 20 and receive values ​​detected by the third sensor 20. It may be provided that the conveying unit can be arranged fluidically downstream of the third sensor 20, for example, if the third sensor is located on, in, or near the return line 12.Alternatively, the conveying unit can be arranged fluidically upstream of the third sensor 20, for example, if the third sensor 20 is located on, in, or near the supply line 11. It can be provided that the control unit can take into account the values ​​detected by the third sensor 20 when controlling and / or regulating the conveying unit 5 and / or the further conveying unit 4 and / or the second conveying unit 6.

[0101] Alternatively or additionally, the device 1 can have a further sensor (not shown in the figures) which can be arranged on, in, or near the container 3. The further sensor can be configured to detect the pressure in the container 3. The further sensor can be connected to the control unit and / or exchange data with the control unit. It can be provided that, when controlling and / or regulating the conveying unit 5 and / or the further conveying unit 4 and / or the second conveying unit 6, the control unit can take into account the values ​​detected by the further sensor.

[0102] In some embodiments, a filter 19 may be provided between the reservoir 3 and the printhead 2, and / or between the printhead 2 and the reservoir 3. A corresponding filter 19 may, for example, be provided and / or arranged on and / or in the supply line 11 and / or the return line 12. The filter 19 may be configured to be or be subjected to flow by the printing medium. The filter 19 may be configured to draw and / or remove undissolved air from the printing medium, e.g., ink. The filter 19 may be configured to filter out foreign bodies, impurities, flakes, clumps, agglomerates, or the like from the printing medium.

[0103] In some embodiments, the container 3 may have a level sensor 15, and / or a level sensor 15 may be arranged on, in, and / or near the container 3. The level sensor 15 may be configured to detect a fill level, in particular of pressure medium, in the container 3. It may be provided that the control unit can be connected to the level sensor 15 in order to receive values ​​detected by the level sensor 15, in particular a fill level.

[0104] Alternatively or additionally, the container 3 may have a sight glass, and / or a side wall of the container 3 may be at least partially transparent. This allows for visual monitoring of the fill level of the container 3. Visual monitoring may be advantageous and / or more reliable than, for example, a float or other sensor, as the float may, in some cases, become stuck to the edge of the container. Alternatively or additionally, it may be possible to use visual monitoring to check whether the pressurizing medium in the container 3 is foaming.

[0105] Lighting may be provided, which may facilitate and / or improve visual inspection depending on the type of visual inspection and / or the environment. The lighting may be located on, at, or in the container 3 and / or the sight glass.

[0106] Alternatively or additionally, the fill level can be measured using at least one capacitive sensor. Alternatively or additionally, the fill level can be determined based on the pressure difference, and / or using the pressure difference.

[0107] In some embodiments, the container 3 may have a temperature sensor 17, and / or a temperature sensor 17 may be arranged on, in, and / or near the container 3. The temperature sensor 17 may be configured to detect the temperature of the pressurised medium contained in the container 3. The temperature sensor 17 may be connected to the control unit, and the control unit may receive values ​​detected by the temperature sensor 17.

[0108] In some embodiments, the device 1 may have a reservoir 21. The reservoir 21 may hold and / or receive pressure medium. The reservoir 21 may serve to replenish pressure medium, for example, when pressure medium is used or has been used for printing. The reservoir 21 may be fluidically connected to the container 3. The reservoir 21 may be connected to the container 3 via a line 13. The device 1 may have a pump 22. The pump 22 may be used and / or configured to supply and / or pump pressure medium from the reservoir 21 to the container 3. The control unit may be connected to the pump 22 and / or be able to control and / or regulate the pump 22.In some embodiments, it may be provided that if the minimum fill level in the container 3 is or becomes below a certain level, the pump 22 can be controlled in such a way that pressure medium can flow from the reservoir 21 into the container 3.

[0109] In some embodiments, a filter 19 may be provided that filters the pressure medium supplied to the container 3 from the reservoir 21. For example, the filter 19 may be arranged on and / or in the line 13. The filter 19 may be configured to be or be subjected to flow by the pressure medium. The filter 19 may be configured to draw out and / or remove undissolved air from the pressure medium, e.g., ink. The filter 19 may be configured to filter out foreign bodies, impurities, flakes, lumps, or the like from the pressure medium.

[0110] The device 1 may include a sealing valve 23. In some embodiments, the sealing valve 23 may be associated with the container 3 and / or configured to seal and / or tighten the container 3. The sealing valve 23 may be arranged fluidically between the container 3 and the pressure control unit 5 and / or fluidically seal the container 3 against the pressure control unit 5. In some embodiments, the sealing valve 23 may be arranged on or in the line 14. The control unit may be connected to the sealing valve 23 and / or control and / or regulate the sealing valve 23.

[0111] The sealing valve 23 can, in particular when the device 1, and / or the inkjet printer, is in a standby state and / or is being moved into a standby state, seal the container 3. This ensures that no printing medium can escape from the printhead 2 in the standby state, e.g., it cannot drip out.

[0112] It may be provided that the pumping unit 4 and / or the second pumping unit 6 can be arranged in the container and / or integrated into the container 3. For example, if the pumping unit 4 and / or the second pumping unit 6 is arranged in and / or integrated into the container 3, space savings and / or easier maintenance and / or accessibility may result. The pumping unit 4 and / or the second pumping unit 6 can be low-vibration and / or generate only minimal vibration during operation, thus enabling arrangement and / or integration within the container 3. The pumping unit 4 and / or the second pumping unit 6 can, for example, be a micro gear pump, which can be low-vibration and / or essentially pulse-free during flow. This can, for example,When arranged and / or integrated in the container 3, this results in a pressure setting and / or flow of pressure medium to and / or from the printhead 2 that is essentially undisturbed by the conveying unit 4 and / or the second conveying unit 6.

[0113] The features disclosed in the foregoing description, the claims and the drawing may be essential for the realization of the invention, both individually and in any combination. Reference symbol list

[0114] 1 Device 2 Printhead 3 Container 4 Conveyor unit 5 Pressure setting unit 6 Second conveying unit 7 First sensor 8 Second sensor 9 Inlet 10 Outlet 11 Supply line 12 Return line 13 Line 14 Line 15 Level sensor 16 Container unit 17 Temperature sensor 18 Bottom 19 Filter 20 Third sensor 21 Reservoir 22 Pump 23 Sealing valve

Claims

1. Device (1) for printing on a printing substrate, comprising: - a printhead (2) for printing on a printing substrate with a printing medium, - a container (3) for receiving the printing medium, - a first sensor (7), - a second sensor (8), - a conveying unit (4) for conveying printing medium, and - a control unit, wherein the container (3) is fluidically connected to an inlet (9) of the printhead (2) and fluidically to an outlet (10) of the printhead (2), so that printing medium can flow from the container (3) through the printhead (2) into the container (3), wherein the first sensor (7) is configured to detect a property of the printing medium when printing medium flows from the container (3) to the printhead (2), and the second sensor (8) is configured to detect a property of the printing medium when printing medium flows from the printhead (2) to the container (3).wherein the conveying unit (4) is arranged fluidically between the container (3) and the printhead (2), wherein pressure medium can flow from the container (3) through the conveying unit (4) to the printhead (2), or wherein pressure medium can flow from the printhead (2) through the conveying unit (4) to the container (3), wherein the control unit is configured to control the conveying unit (4) based on the property detected by the first sensor (7) and / or the second sensor (8).

2. Device (1) according to claim 1, wherein the pumping unit (4) is or comprises a pump, preferably a micro gear pump and / or a gas pump.

3. Device (1) according to one of the preceding claims, wherein the control unit is configured to control the conveying unit (4) such that the meniscus pressure of the printhead (2) is between -50 mbar and 500 mbar, preferably between -50 mbar and 250 mbar.

4. Device (1) according to one of the preceding claims, wherein the control unit is configured to control a delivery quantity and / or a delivery pressure of the delivery unit (4) based on the property detected by the first sensor (7) and / or the second sensor (8).

5. Device (1) according to one of the preceding claims, wherein the first sensor (7) and / or the second sensor (8) is or comprises a pressure sensor.

6. Device (1) according to one of the preceding claims, wherein the first sensor (7) and the second sensor (8) are configured to detect a pressure of the pressure medium, and the control unit is configured to determine a pressure difference of the pressures detected by the first sensor (7) and the second sensor (8) and to control the first pressure setting unit and / or the second pressure setting unit (5) based on the pressure difference.

7. Device (1) according to one of the preceding claims, wherein the first sensor (7) and the second sensor (8) are configured to detect a pressure of the pressure medium, and the control unit is configured to determine an average of the pressures detected by the first sensor (7) and the second sensor (8) and to control the first pressure setting unit and / or the second pressure setting unit (5) based on the average.

8. Device (1) according to one of the preceding claims, wherein the conveying unit (4) is arranged fluidically upstream of the first sensor (7) or fluidically downstream of the second sensor (8).

9. Device (1) according to one of the preceding claims, comprising a second conveying unit (6), wherein the conveying unit (4) is arranged such that pressure medium from the container (3) can flow through the conveying unit (4) to the printhead (2) and the second conveying unit (6) is arranged such that pressure medium from the printhead (2) can flow through the conveying unit (4) to the container (3).

10. Device (1) according to claim 9, wherein the second conveying unit (6) is arranged fluidically after the second sensor (8).

11. Device (1) according to one of the preceding claims, comprising a pressure setting unit (5) configured to set a pressure in the container (3).

12. Device (1) according to claim 11, wherein the pressure setting unit (5) is or comprises a proportional valve and / or a gas pump.

13. Method for controlling a device (1) for printing on a printing substrate, comprising the steps of: - detecting a property of a pressure medium flowing from a container (3) of the device (1) to a printhead (2) of the device (1) with a first sensor (7); - detecting a property of a pressure medium flowing from the printhead (2) to the container (3) of the device (1) with a second sensor (8); and - controlling, based on the properties of the pressure medium detected by the first and second sensors (8), a delivery unit (4) of the device (1), wherein the delivery unit (4) sets a delivery pressure and / or a delivery rate of the pressure medium based on the properties detected by the first and second sensors (8).

14. Method according to claim 13, wherein the conveying unit (4) is controlled such that the meniscus pressure of the printhead (2) is between -50 mbar and 500 mbar, preferably between -50 mbar and 250 mbar.

15. Method according to claim 13 or 14, wherein the first sensor (7) and the second sensor (8) measure a pressure, a pressure difference and / or an average of the pressures detected by the first sensor (7) and the second sensor (8) is determined, and the conveying unit (4) is controlled based on the pressure difference and / or the average.

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