Background

[0001] In some printing systems, a printhead receives a stream of printing fluid towards a printhead from a supply tank or container, such an arrangement is known as a fluid delivery sub-system or a fluid supply sub-system. In such a sub-system, printing fluid can be fed from a tank or a supply to the printhead using, e.g., a pump and printing fluid parameters such as a flow rate and flow direction may be measured using flowmeters.

[0002] Particularly, inkjet printing systems are, in general terms, controllable fluid ejection devices that, propel droplets of printing fluid from a nozzle within the printhead to form an image on a substrate wherein such propelling can be achieved by different technologies such as, e.g., thermal injection or piezo injection

Description of Drawings

[ooosJThe following detailed description will best be understood with re.fere.nce to the drawings, wherein:

[0004] Fig. 1 shows a cross-section of a flowmeter according to an example:

[0005] Fig. 2 shows a further example of a flowmeter:

[0006] Fig. 3 shows an example of part of a fluid delivery sub-system including a flowmeter according to an example.

[0007] Fig. 4 shows a further example of part of a fluid delivery’ sub-system including a flowmeter.

[0008] Fig. 5 shows a flow-chart of a method for measuring a printing fluid flow’ parameter according to an example.

Description of Examples

[0009] In the foregoing, a printing fluid monitoring device is disclosed, printing fluid flow-meter comprising:

- a first port and a second port to be connected within a fluid path;

- a sensing tube between the first port and the second port, the sensing tube comprising a loop; - a plurality of ferromagnetic elements wit hin the sensing tube; and

- an interface element circled by the, loop and magnetically coupled to the ferromagnetic elements; and

- - a detector to determine a rotation parameter of the interface element; wherein the flowmeter comprises a processor to determine, based on the rotation parameter, a flow parameter.

[0010] In an example, the detector comprises an encoder to read a code within the interface element, the encoder being connected to the processor. In this way, the encoder may be provided to read a code that moves together with the interface element and the encoder may determine a rotation parameter based on such reading, e.g., may determine the rotation direction and/or the rotational speed that are proportional to the flow direction and flow magnitude respectively.

[0011] In a further example, the detector comprises a hall effect sensor in this way, the detector may determine a rotation parameter associated to a magnetic component provided within the interface element, e.g.., the magnetic component that couples the interface element, to the ferromagnetic elements.

[0012] As mentioned above, the flow parameter may include a direction of the printing fluid along the fluid path.

[0013] As for the interface element, it may comprise a plurality of spokes associated to each of the plurality of ferromagnetic elements. In such an example, the detector may count a pass frequency of at least some of the plural ity of the spokes and wherein the processor is to determine the flow parameter based on the pass frequency. In an example, at least some of the plurality of arms comprise, a code and wherein the. flowmeter comprises an encoder to read the code.

[0014] In an example, the sensing tube has a different diameter than the diameters of the first port and the second port. For example, the sensing tube may have a diameter slightly larger than the diameter of the ports thereby allowing to maintain ferromagnetic elements or a size such that they can travel through the sensing tube and may not travel through the ports and reach other portions of the fluid deliver}' sub-system. In addition or instead of having different sizes for the. sensing tubes and the ports, the first port and the second port comprise a restraining element to maintain the ferromagnetic elements within the sensing tube. [0015] Furthermore, it is herein described a printing system, including a printing fluid delivery subsystem, wherein the printing system comprises a flowmeter within a fluid path of the fluid delivery subsystem, the flowmeter having:

- - a first port couplable to a printing fluid conductor within the printing fluid media path in a first position;

- a second port couplable to the printing fluid conductor in a second position downstream the first position;

- a sensing tube having a plurality of ferromagnetic elements that move along the tube, the tube defining a loop between the first port and the second port; and

- an interface, element within the, loop, the, interface element being external to the, tube and magnetically coupled to the ferromagnetic elements; wherein the flowmeter comprises a processor to determine a printing fluid flow parameter based on a rotation of the interface element.

[0016] In an example, the printing fluid flow parameter includes at least one of: a flow direction of the printing fluid, or a flow magnitude of the printing fluid.

[0017] In a further example,, the flowmeter comprises an encoder and a code fixed to the interface element, being the code to be read by the encoder and thereby determine a flow direction of the printing fluid and/or a flow magnitude.

[0018] Also, the sensing tube may, in an example, have a different diameter than the printing fluid conductor as to prevent the movement of the ferromagnetic elements outside the sensing tube.

[0019] Further, the present disclosure refers to a printing fluid flow measurement method by using a flowmeter that comprises a measurement tube defining a looped trajectory, the measuring tube including a plurality of ferromagnetic elements, the method comprising a processor to:

- pump a printing fluid through a fluid conductor and the flowmeter;

- - determine a rotation parameter of an interface element encircled by the measurement tube, the interface element being magnetically coupled to the ferromagnetic elements; and

- determine, a printing fluid flow parameter based on the rotation parameter.

[0020] In an example of the above-captioned method, the processor may further determine a printing fluid direction based on the rotation parameter. [0021] In the following description and figures, some example implementations of print apparatus, prin t systems, and/or methods of printing are described. In examples described herein, a “printing system” may be a system to print content on a physical medium (e.g., paper, textiles, a layer of powder-based build material, etc.) with a print material (e.g., ink or toner). For example, the printing system may be a wide-format print apparatus that prints latex-based print fluid on a print medium, such as a print medium that is size A2 or larger. In some examples, the physical medium printed on may be a web roll or a pre-cut sheet. In the case of printing on a layer of powder-based build material, the print apparatus may utilize the deposition of print materials in a layer-wise additive manufacturing process. A printing system may utilize suitable print consumables, such as ink, toner, fluids or powders, or other raw’ materials for printing. In some examples, the printing system may be a three- dimensional (3D) printer. An example of fluid print material or printing fluid is a waterbased latex ink ejectable from a print head, such as a piezoelectric print head or a thermal inkjet print head. Other examples of print fluid may include dye-based color inks, pigmentbased inks, solvents, gloss enhancers, fixer agents, and the like.

[0022] Fig. 1 show's.an example of a flowmeter according to an example, the flowmeter is to measure a flow parameter associated to a fluid delivery sub-system of a printing system. In the example shown in figure 1, the flowmeter 1 comprises a pair of input/output ports, in particular, a first port 2 and a second port. 3. The. ports 2, 3 are considered to be. input/output ports given the ability’ of the flowmeter 1 to measure flow- independently of its direction, in fact, the flow-meter 1 may measure the flow- direction also as a flow’ parameter that may be measured by the flow-meter 1.

[0023] Furthermore, in the context of the present disclosure, the term “port” may be understood as a piece of the flowmeter that is connectable to other elements within a print delivery sub-system as may be, e.g., tubing, valves, pumps, tanks, etc.

[0024] Turning back to fig. 1, the flowmeter 1 receives an input flow 21 of printing fluid through one of its ports, in the example of fig. 1 the first port 21. Such input flow 21 reaches a sensing tube.4 wherein a plurality of ferromagnetic elements 41 are provided such as the. ferrom agnetic balls of fig. 1. Upon contact with the input flow- 21 the ferromagnetic elements 41 travel along a looped trajectory 40 defined by the sensing tube 4 with a speed proportional to the flow- rate of the input flow- 21.

[0025] The flowmeter also comprises an interface element 42 that is magnetically coupled to the ferromagnetic elements 41. The interface element 42 is surrounded by the sensing tube 4 so that the movement of the ferromagnetic elements 41 along the sensing tube, and therefore following the looped trajectory 40, cause a rotation 43 on the interface element 42. Therefore, the flowmeter 1 may measure flow parameters of the input flow 21 by determining rotation parameters of the interface element 42, e.g., the rotation direction corresponds to the flow direction, and the angular speed of the interface, elements is proportional to the flowmagnitude of the input flow 21.

[0026] A printing fluid may be an ink, such as a color ink, including CMYK inks, and white ink. The ink may be. a latex ink or another type of ink. In other examples, the printing fluid can be a type of conditioning fluid used in inkjet type printers, including 2D and 3D printer such as overcoats, fixers, fusing agents, etc. The printer may be, may include, or may be. part of a large format printer, for example.

[0027] The magnetic coupling between the interface element 42 and the ferromagnetic elements 41 is achieved by the interface element being manufactured of or including a magnetic component. In an example, the interface element comprises a plurality of radial elements, i.e., spokes being the spokes associated to the ferromagnetic elements 41, e.g., each spoke may be. associated to a ferromagnetic element.

[0028]The flowmeter of fig. i also includes a detector 5 to determine, a rotation parameter associated with the interface element 42. In an example, the detector 5 may be a hall effect sensor that may be to detect the passing frequency of a magnetic element associated to the interface element, e.g., a magnetic element in the spokes. Such rotation parameter may then be communicated to a processor that may determine a flow parameter, e.g., a flow magnitude and direction based on the rotational speed and direction of the interface, element respectively.

[0029] Also, in an example, the flowmeter 1 has a different diameter in the sensing tube 4 than in the input/output ports 2, 3. An advantage of having different diameters in the sensing tube is that, e.g., the ferromagnetic elements 41 may be. of a size such that the magnetic elements 41 can travel through the sensing tube 4 but cannot pass the input/output ports 2, 3, thereby ensuring that such elements do not end up in unwanted sections of the fluid deliver}- sub-system. Another alternative is to provide restraining elements, such as filters, between the input/output ports 2, 3 and the sensing tube.

[0030] An example, of the sensing approach described herein relies on non-contact sensing, this sensing capability allows for the detector to have no interaction with the printing fluid thereby avoiding creating new printing fluid quality issues and being a more robust solution, e.g., in case, of corrosive, printing fluids that may damage sensors that are in contact with the. printing fluid. In the examples provided herein only the ferromagnetic elements are in contact with the printing fluid and such elements may be built with robust materials at a relatively low cost.

[0031] The processor may be any combination of hardware, and programming to implement the functionalities described herein. These combinations of hardware and programming may be implemented in a number of different ways. In certain implementations, the programming for the processor, and its component parts, may be in the form of processor executable instructions stored on at least one non-transitory machine-readable storage medium and the hardware for the engines may include at least one processing resource, to execute those instructions. The processing resource may form part of the monitoring device 2 or be part of the printing system to which the monitoring device 2 is connected, or a computing device that is communicatively coupled to the. printing system. In some implementations, the hardware may include electronic circuitry to at least partially implement the processor 220. For example, the processor 220 may comprise an application-specific integrated circuit that forms part of a printing device within the printing system

[0032] .Fig. 2 shows an example of a flowmeter 1 having a first port 2 and a second port 3 wherein, as in the case of the example of fig.i, the ports are input/output ports, i.e., the flowmeter is a bidirectional flowmeter. In the example, of fig. 2, the flowmeter also comprises a sensing tube 4 wherein ferromagnetic elements are provided and an interface element 42 that rotates as the ferromagnetic elements move along the looped trajectory of the sensing tube 4 by the effect of printing fluid that flows between the input/output ports 2, 3.

[0033] In particular, the flowmeter 1 of fig. 2 comprises an encoder disk 6 fixed to the interface element 42 as to jointly rotate. Also, the flowmeter 1 comprises a detector 5 that, in this case, is a reader that is to read a pattern (i.e., a code.) within the encoder disk and, based on the reading of such pattern, determine the rotational speed and/or the direction of rotation of the encoder disk and, as a consequence, of the interface element 42 and then, together with the processor, translate that rotational speed into one. or several flow' parameters.

[0034] The detector 5 or, in the case of the example of fig. 2, the reader may be provided with a communication link to the processor (not shown) and the processor may be provided with processing capabilities as to determine a flow' parameter (e.g., a flow magnitude, a flow direction) based on the rotation parameter determined by the processor that, in turn, is based on information gathered by the. reader.

[0035] As discussed, the examples provided herein discuss the use of sensors wherein the electronics and/or sensitive components are not in contact with the printing fluid. The element in contact with the printing fluid is mainly the ferromagnetic element 41 which may be, e.g., metallic balls which are, robust and low-cost. Other examples of detectors that maybe used are, e.g., mechanical switches that, upon contact with parts of the interface element 42 perform a count similar to that of the encoder/disk arrangement of fig. 2 or the hall effect sensor o fig. 1.

[0036] Fig. 3 show-s an example of the flowmeter 1 in conjunction with a pump 7 to be used, for example, in a printing fluid delivery sub-system of a printing system. The fluid delivery sub-system is a sub-system that has the main function of transferring a printing fluid from a printing fluid container to a printhead. The printing fluid delivery'- sub-system, therefore, may include pumps, intermediate tanks, purging elements and means for ensuring appropriate pressure and flow level across the printing fluid delivery sub-system.

[0037] The example of fig. 3 show's a pump 7 that is to maintain a printing fluid within a determined range of flowrates, e.g., in a flowrate between 50 cc/min and 250 cc/min. The flowmeter 1 comprises a detector 5 that may be an encoder disk 6 and reader 5 arrangement as shown in the figure but may also be a hall effect sensor or a mechanical arrangement as previously disclosed.

[0038] The detector 5 is connected to a processor 8 by a first communication link that may be a wired or wireless connection and the processor 8 is to determine a flowrate currently- passing through the flowmeter 1 based on the input received from the detector 5. In an example, the. processor 8 may also have access to a set flow-rate and may communicate, via a second communication link 70 with the pump 7 as to set its operating flowrate.

[0039] Fig. 4 shows a further example of the application of the flowmeter 1 in a printing fluid delivery- sub-system. In the example of fig. 4 the printing fluid delivery- sub-system includes a pump 7, an intermediate tank 9 and a printing fluid supply' 10.

[0040] In such an application, the pump 7 may be to pump printing fluid from the printing fluid supply 10 towards the intermediate tank 9 that in turn, supplies the printheads of the printing system with printing fluid. In this operating mode. the. pump would be. working in a printing mode, i.e., printing fluid travels in a first direction from the supply towards the intermediate tank.

[0041] In a further operation mode, e.g., in a recirculation mode, the pump 7 would be to pump printing fluid from the printheads through the intermediate tank 9 and towards the supply 10 to achieve a recirculation of the printing fluid, e.g., to prevent pigments in the printing fluid to settle, to reduce a temperature of the printing fluid or to move air bubbles that may’ be present in the printing fluid delivery system towards the supply- 10. In this recirculation mode, the printing fluid travels in a second direction opposite to the first direction, i.e., from the intermediate tank 9 towards the supply to.

[0042] The example flowmeter 1 of fig. 4 is capable of measuring a flow parameter in both of the above-mentioned operating modes, i.e., is a bi-directional flow meter. In particular, while the printing system is working in a printing mode the printing fluid flow's from the supply 10 towards the intermediate tank 9 and, therefore, the intermediate element 42 would rotate in a clockwise direction 101. The flowmeter 1 together with the processor may determine the magnitude of flow flowing through the flowmeter 1 and, also, determine, that the printing fluid is travelling in a direction that corresponds with the printing mode.

[0043] Likewise, if the printing system works in a recirculation mode, the printing fluid would travel in a direction opposite to the direction in the printing mode. In such a case, the flowmeter follows the same principle for measuring the flow' magnitude and would be able to determine the direction of the printing fluid due to the rotation of the intermedia element 42 in a counterclockwise direction 102.

[0044] Fig. 5 is an example, flowchart for measuring a flow' parameter. In the. example of fig. 5, the method comprises pumping a fluid trough a printing fluid conductor and a flowmeter comprising a loop 501. In such a case, the associated printing system has been previously configured to operate in a printing or recirculation mode, therefore, defining the direction of travel of the printing fluid.

[0045] Upon receipt of printing fluid therethrough, the flowmeter and its associated loop within a sensing tube of the. flowmeter, due. to ferromagnetic elements within the sensing tube being magnetically coupled to an interface element may force a rotation of such interface element. In turn, the method comprises to determine a rotation parameter of an interface element encircled by the loop 502. In an example, the rotation parameter includes the rotation direction and/or rotational speed of the interface element.

[0046] Such rotation parameter (or parameters) are then forwarded to a processor. The processor may be. to gather the rotation parameter and determine a printing flow parameter based on the rotation parameter 503, i.e., transduce the rotational parameter into a flow' parameter. Following the above-mentioned example, if the rotation parameter is a rotational speed, the flow parameter m ay be a flow' m agnitude and, if the rotation parameter is the rotation direction of the interface element, the flow' parameter may be a flow direction.

[0047] Without further analysis, the foregoing so fully reveals the gist of the present inventive concepts that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute the characteristics of the generic or specific aspects of this invention. Therefore, such applications should and are intended to be. comprehended within the meaning and range of equivalents of the following claims. Although this invention has been described in terms of certain embodiments, other embodiments that are apparent to those of ordinary skill in the art are. also within the scope, of this invention, as defined in the claims that follow.