Patent Application
20240208228
Some print apparatuses use a print fluid application unit to deliver print agent, such as ink, onto a printable substrate. As the print fluid application unit scans over the printable substrate, drops of ink may be delivered through nozzles of the print fluid application unit in accordance with an image or pattern defined in image data, to form an image on the printable substrate.
During the printing process, residual ink which has not been deposited onto the printable substrate may remain in the nozzles and, if left, may dry and could cause the nozzles to become blocked.
Examples will now be described, by way of non-limiting example, with reference to the accompanying drawings, in which:
Examples disclosed herein may be applicable to all types of printing in which print agent (sometimes referred to as print fluid), such as ink, is delivered onto a surface using a print agent distributor (sometimes referred to as a print fluid application unit or print head). Examples are applicable to two-dimensional (2D) print systems, such as inkjet print systems, in which ink is deposited onto a printable substrate via nozzles of a print head. Similarly, examples are applicable to three-dimensional (3D) print systems, also referred to as additive manufacturing systems, in which three-dimensional objects are generated.
Referring briefly to three-dimensional print systems, additive manufacturing techniques may generate a three-dimensional object through the solidification of a build material. In some examples, the build material may be a powder-like granular material, which may for example be a plastic, ceramic or metal powder. The properties of generated objects may depend on the type of build material and the type of solidification mechanism used. Build material may be deposited, for example on a print bed and processed layer by layer, for example within a fabrication chamber.
In some examples, at least one print agent may be selectively applied to the build material, and may be liquid when applied. For example, a fusing agent (also termed a ‘coalescence agent’ or ‘coalescing agent’) may be selectively distributed onto portions of a layer of build material in a pattern derived from data representing a slice of a three-dimensional object to be generated (which may for example be generated from structural design data). The fusing agent may have a composition which absorbs energy such that, when energy (for example, heat) is applied to the layer, the build material coalesces and solidifies to form a slice of the three-dimensional object in accordance with the pattern. The print agent may be deposited onto the build material via nozzles of a print agent distributor.
In some two-dimensional print apparatuses, print agent or print fluid, such as ink, may be deposited onto a printable medium, such as paper or card, using a print head, which may be referred to as a print fluid application unit. Such a print head may include a nozzle or multiple nozzles, through which print fluid can be deposited during a printing operation, in order to mark the printable medium. Some print apparatuses may include multiple print heads, and each print head may deposit print fluid of a particular color, or may deposit print fluid of multiple colors. Print fluid may be supplied to the nozzles of the print head(s) from a print fluid source. In some examples, print fluid may be stored in a print fluid reservoir, for example in a cartridge which may be replaceable. The print fluid reservoir or cartridge may be in fluid communication with nozzles of the print head through which print fluid is to be deposited.
When print fluid is deposited from nozzles of a print head during a printing operation, some print fluid may remain in or at the ends of the nozzles, and this residual print agent may dry and cause nozzles to become blocked, or may create unintended effects on future print fluid depositions through those nozzles. For example, dried print fluid deposits on or around the nozzles may cause nozzles to fire print fluid off target or may cause an intended amount of print fluid to be deposited through the nozzle. Such issues may lead to image quality defects in a printed image. Various techniques may be implemented to remove print fluid from the nozzles before it dries. A spitting procedure may be used to fire print fluid through the nozzles into a spitting region (e.g. a spittoon) so as to clear the nozzles. The nozzles may also be wiped to remove residual print fluid from the ends of the nozzles. In an example of such a wiping procedure, the print head is moved such that the nozzles are brought into contact with a wiping surface. The print head is then moved such that the nozzles are wiped over the wiping surface. In some examples, the wiping surface may comprise a wicking material such that print agent present at the ends of nozzles is wicked away from the nozzles and wiped onto or absorbed by the wiping surface.
In some examples, the wiping surface used to wipe the nozzles of the print head may comprise a web or roll of material which can be advanced (e.g. fed from a feed roller onto a capture roller) to prevent a particular region of the wiping surface from becoming saturated with print fluid.
To avoid unwanted print quality defects, a test image (sometimes referred to as an assessment image or a nozzle check image) may be printed onto the printable medium, before performing a printing operation. However, printing such a test image may use up part of a valuable printable medium (e.g. high-quality card), and the printable medium containing the test image may be removed from the print apparatus before the intended printing operation can begin. Thus, not only does this process result in wastage for the user of the print apparatus, but it also impacts on the productivity of the print apparatus, since the printing operation is not begun until the test image has been printed and analyzed. Examples of the present disclosure provide a mechanism by which the nozzles of a print head can be checked without delaying or interrupting the printing operation. Specifically, according to examples disclosed herein, an image or pattern (e.g. a test image or nozzle check image) is printed onto the wiping surface, rather than the printable medium being used as part of the printing operation. A sensor is used to analyze the printed image in real time, after the image has been printed, and analysis of the image can be used to detect issues with any of the nozzles of the print head(s). By printing the test image on the wiping surface, the printing operation using the printable medium is not adversely affected, and the test image may be printed on the wiping surface during the printing operation, for example while the print head is in position over the wiping surface for a scheduled cleaning event.
Referring now to the drawings,
During a printing operation, the print fluid application unit 104 and the printable medium 112 are moved relative to one another (i.e. the print fluid application unit may be moved over the printable medium and/or the printable medium may be moved under the print fluid application unit) as print fluid is deposited from the nozzles 110. When the print fluid application unit 104 is to undergo a maintenance operation (e.g. a nozzle cleaning operation), the print fluid application unit 104 may be brought into a position where the nozzles 110 can contact the nozzle cleaning surface 108. Thus, in some examples, the print fluid application unit 104 may be moved from a position over the printable medium 112 to a position over the nozzle cleaning surface 108 while, in other examples, the nozzle cleaning surface may be moved into a position beneath the print fluid application unit. In one example, the fluid application unit 104 is movable along an axis in a direction indicated by the double-headed dashed arrow A in
The scanning unit 106 may be used to scan (e.g. capture an image of) a surface, such as a surface of the printable medium 112 and/or the nozzle cleaning surface 108. More particularly, the scanning unit 106 may scan an image, mark or pattern formed on a surface. In some examples, the scanning unit 106 may be considered to be a sensor or an image capture device. Such a sensor may detect, measure and/or or capture an image of a mark, pattern or image formed on a surface, for example by print fluid deposited from nozzles of the print fluid application unit 104. In the example shown in
The controller 102, which may comprise a processor or multiple processors for example, may perform various functions operate the various components of the print apparatus 100. The controller 102 is to control the print fluid application unit 104 to deposit print fluid from a nozzle or nozzles of the plurality of nozzles 110 according to an intended pattern onto the nozzle cleaning surface 108. The intended pattern may, for example, comprise a test image or a nozzle check image or pattern in which a nozzle 110 of the print fluid application unit 104 is intended to deposit print fluid onto the nozzle cleaning surface 108 in such a way that it can be detected, sensed or imaged using the scanning unit 106. For example, through control of the print fluid application unit 104 by the controller 102, a plurality of nozzles 110 may deposit print fluid onto the nozzle cleaning service 108 to form a discrete deposit or mark. For example, a mark formed by a first nozzle may be separated (e.g. discrete) from a mark formed by any nozzle adjacent to the first nozzle. In this way, by depositing print fluid according to a particular intended pattern, any errors, omissions, and/or misalignments in the pattern can be detected, and a determination can be made as to which nozzle or nozzles are responsible.
The controller 102 is to control the scanning unit 106 to scan the pattern formed on the nozzle cleaning surface 108. As noted above, the scanning unit 106 may comprise a sensor that detects marks formed on the surface being scanned (i.e. the nozzle cleaning surface 108), such that the controller 102 or another processing device is able to record the presence or omission of a mark that is intended or expected to be present according to the intended pattern. In a more sophisticated example, the scanning unit 106 may comprise an image capture device that captures an image or multiple images of the marks as they are being formed or after they have been formed on the surface being scanned. The controller 102 or another processing device may then analyze the image or images to determine whether or not the marks are in accordance with the intended pattern. If all of the nozzles 110 that were intended to deposit print fluid do actually deposit print fluid according to the intended pattern, then the controller 102 or another processing device may determine that those nozzles whose deposits have been analyzed are functioning as intended and that maintenance of those nozzles is not to be performed at that time. However, if the controller 102 or another processing device determines that a nozzle or multiple nozzles that were intended to deposit print fluid have failed to deposit print fluid according to the intended pattern (e.g. by failing to deposit print fluid at all or by depositing print fluid forming a mark other than intended), then it may be determined that the respective nozzle or nozzles are defective (e.g. blocked or broken). Thus, responsive to determining, based on the scan, that print fluid from a nozzle 110 of the plurality of nozzles has not been deposited according to the intended pattern, the controller 102 is to generate an instruction signal regarding maintenance of the print fluid application unit 104.
If it is determined by the controller 102 that the deposits from the nozzles 110 are not in accordance with the intended pattern, then the controller generates an instruction signal that may cause the print fluid application unit 102 to undergo a maintenance operation. The nature of the maintenance and, therefore, the instruction signal generated by the controller 102 may depend on the degree to which the intended pattern has (or has not) been printed. For example, if the controller 102 determines that a mark made by a single nozzle 110 is slightly misaligned with regard to its intended alignment according to the intended pattern, then the controller may generate an instruction signal to schedule a maintenance operation (e.g. a nozzle cleaning operation) at a particular time or following completion of the current printing operation. However, if the controller 102 determines that several nozzles (e.g. more than a defined threshold number of nozzles) have failed to deposit print fluid according to the intended pattern, then this may be recognised as a more significant defect with a greater likelihood of causing an image quality defect in a printed image and, therefore, the controller may generate an instruction signal to cause a maintenance operation to be performed in respect of the print fluid application unit 104 or in respect of a subset of nozzles (e.g. those nozzles exhibiting defective deposits). In some examples, the instruction signal regarding maintenance of the print fluid application unit 104 may comprise a signal to cause the nozzle 110 of the print fluid application unit to be wiped by the nozzle cleaning surface 108. As discussed below, other instruction signals may be generated by the controller 102 in response to determining that a nozzle 110 has failed to deposit print fluid according to the intended pattern.
According to the example shown in
The scanning unit 106 (and/or the second scanning unit 106′) may comprise an optical sensor to detect deposits of print fluid formed on the nozzle cleaning surface 108 by a nozzle or nozzles 110 of the plurality of nozzles. As noted above, the scanning unit 106, 106′ may comprise an image capture device such as a camera, which may capture an image or a stream of images showing the print fluid deposits (e.g. the marks) formed on the nozzle cleaning surface 108.
In the example shown in
The pattern 304 shown in
While the scanning unit 106 may be used for scanning the marks or patterns
304 formed by the nozzles, in order to check their adherence to the intended pattern, the data acquired using the scanning unit may also serve other purposes. In one example, the scanning unit 106 may scan the nozzle cleaning surface 108 as the scanning unit passes over the nozzle cleaning surface, and a determination may be made regarding whether or not the nozzle cleaning surface has received more than a defined threshold amount of print fluid. If the threshold amount of print fluid has been deposited onto the nozzle cleaning surface, then it may be determined that the nozzle cleaning surface (e.g. in the form of a web of material) should be advanced, and rolled onto the roller 114b, thereby revealing a portion of clean, unused web on which future cleaning operations may be performed or on which print fluid may be deposited according to the intended pattern. Thus, in some examples, the nozzle cleaning surface 108 may comprise a web of material. In such examples, the controller 102 may be to generate an instruction signal to advance the web of material, responsive to determining, based on the scan, that a defined threshold amount (e.g. a first defined threshold amount) of print fluid has been deposited onto a portion of the nozzle cleaning surface onto which the print fluid is to be deposited. In this way, when it is intended to deposit print agent according to the intended pattern, the nozzle cleaning surface 108 can be checked and, if it is too dirty, then the web can be advanced so that the pattern can be deposited onto a clean portion of the web, thereby improving the likelihood of an accurate analysis of the printed pattern.
In other examples, the scanning unit 106 may be used to determine if the nozzle cleaning surface 108 has become saturated (e.g. if too much print fluid has been deposited over the entire web of material) such that the web of material is due to be replaced. Thus, in examples where the nozzle cleaning surface 108 comprises a web of material, the controller 102 may be to generate an alert signal, responsive to determining, based on the scan, that an amount of print fluid that has been deposited onto the nozzle cleaning surface meets or exceeds a defined threshold amount (e.g. a second defined threshold amount). The second defined threshold amount may be more than the first defined threshold amount. In this example, the alert signal may comprise a signal to be presented to an operator of the print apparatus (e.g. via a computing device such as a desktop computer, a laptop computer, a smart phone, a wearable device or via a display on or associated with the print apparatus itself) indicating that the web of material used as the nozzle cleaning surface is dirty and is to be replaced. In other examples, the alert signal may comprise an instruction to cause the print apparatus to halt printing or pause the printing operation until the nozzle cleaning surface has been replaced.
In the examples shown in
At block 404, the method 400 comprises scanning the printed assessment pattern with an image scanner 106 to generate a scanned assessment image. The image scanner 106 may comprise the scanning unit discussed above, and may for example comprise an image capture device such as a camera. The scanned assessment image may comprise an image of the pattern 304 formed on the nozzle cleaning surface 108.
The method 400 comprises, at block 406, determining, from the scanned assessment image, whether any of the nozzles of the plurality of nozzles 110 failed to deliver print agent in accordance with the assessment pattern. Such a determination may be made if it is apparent from the scanned assessment image that any part of the image is not in accordance with the assessment pattern. For example, the determination of a failure may be made if a mark formed by any nozzle is misaligned with respect to its intended alignment, if a mark formed by any nozzle is missing, when the mark appears in the assessment pattern, or if a mark appears too dark, too light, too large, or too small with respect to its intended appearance in the assessment pattern. In other examples, other assessment metrics may be used to determine whether or not the print agent has been delivered in accordance with the assessment pattern.
At block 408, the method 400 comprises performing corrective action if it is determined that a particular nozzle of the plurality of nozzles 110 has failed to deliver print agent in accordance with the assessment pattern. Depending on the nature of the failure, different corrective actions may be taken and the timing of the corrective action may also depend on the nature of the failure. In some examples, the corrective action may comprise an action selected from a group of actions. For example, the corrective action may comprise providing a notification for delivery to an operator of the print apparatus. Such a notification may inform the operator that a nozzle defect has been detected and that corrective action is to be taken. In other examples such a notification may inform the operator that the nozzle wiping surface of the print apparatus is to be replaced. In some examples, the corrective action may comprise performing or scheduling a nozzle wiping operation in respect of the particular nozzle. For example, if it is determined that a nozzle is dirty or clogged with print agent or that a group of nozzles are misfiring due to being clogged with print agent, then those nozzles may be wiped immediately on the nozzle wiping surface 108 or a nozzle wiping operation may be scheduled for the next occasion that the print head moves over the nozzle wiping surface. In some examples, the corrective action may comprise performing a realignment action in respect of the particular nozzle. For example, if the printed assessment pattern indicates that the nozzle itself is misaligned or that print agent fired from the nozzle is deposited in a position different to the intended position, then realignment of the nozzle may be effected. In some examples, the corrective action may comprise deactivating the particular nozzle. A nozzle may be deactivated if, for example, the nozzle has failed to deposit print agent in accordance with the intended assessment pattern on multiple occasions (e.g. on three consecutive occasions). In some examples, the corrective action may comprise arranging for a different nozzle to deliver print agent instead of the particular nozzle. For example, if the particular nozzle fails to deposit print agent, or if the particular nozzle has been deactivated, then a nozzle, or multiple nozzles, adjacent to or near to the particular nozzle may be used to deposit extra print agent to compensate for the particular nozzle. In some examples, the corrective action may comprise arranging for the print apparatus to halt printing or pause a printing operation.
In some examples, nozzles 110 of a print head or of a print fluid application unit 104 may be grouped into sets or subsets. Thus, the print head may comprise a first subset of nozzles and a second subset of nozzles. In some examples, the plurality of nozzles 110 of block 402 may form the first subset of nozzles. In such examples, instructing the delivery of print agent (block 402) may comprise instructing the delivery of print agent from the first subset of nozzles and not from the second subset of nozzles. In other words, just a subset of the nozzles may be used to deliver print agent in accordance with the assessment pattern and the nozzle wiping surface 108. In this way, subsets of the nozzles 110 may be assessed separately. For example, nozzles that are not currently being used in a printing operation may be assessed according to the method 400, 500 without impacting on the printing operation.
The print apparatus 100, 200 may perform a maintenance operation, such as a nozzle wiping operation, at intervals during a printing operation, or between printing operations. The methods 400, 500 discussed herein may be performed at any time. However, performing the blocks of the methods 400, 500 at the time that coincides with a planned maintenance operation (e.g. when the print head or print fluid application unit 104 is positioned over the nozzle wiping surface 108) can help to reduce downtime of the print apparatus 100200 and can help to reduce the impact on the printing operation. Thus, in some examples, instructing the delivery of print agent (block 402) may comprise instructing the delivery of print agent onto the nozzle wiping surface 108 at a time coinciding with a planned nozzle wiping operation associated with the print head.
The present disclosure also provides a machine-readable medium.
Examples disclosed herein provide a mechanism by which nozzles of a print fluid application unit 104 may print a test image or test pattern during a printing operation, without impacting on the printing operation. This is achieved by causing the test image to be printed onto the nozzle cleaning surface 108, rather than onto the printable medium 112, on which an image is to be printed as part of the printing operation. Furthermore, by scanning or assessing the printed test image in real time, immediately after the test image has been printed, a rapid assessment of the nozzles may be performed, thus identifying any potential defects with the nozzles before any significant print quality defects have been caused in the printing operation. Moreover, by identifying any potential nozzle defects early, remedial action may be taken, such as performing a maintenance operation (e.g. a nozzle wiping operation) to clean the affected nozzles. This also has the effect of prolonging the life of the nozzles and the print fluid application unit 104, by performing appropriate maintenance operations at an appropriate time, rather than merely periodically, when scheduled.
Examples in the present disclosure can be provided as methods, systems or machine readable instructions, such as any combination of software, hardware, firmware or the like. Such machine readable instructions may be included on a computer readable storage medium (including but is not limited to disc storage, CD-ROM, optical storage, etc.) having computer readable program codes therein or thereon.
The present disclosure is described with reference to flow charts and/or block diagrams of the method, devices and systems according to examples of the present disclosure. Although the flow diagrams described above show a specific order of execution, the order of execution may differ from that which is depicted. Blocks described in relation to one flow chart may be combined with those of another flow chart. It shall be understood that each flow and/or block in the flow charts and/or block diagrams, as well as combinations of the flows and/or diagrams in the flow charts and/or block diagrams can be realized by machine readable instructions.
The machine readable instructions may, for example, be executed by a general purpose computer, a special purpose computer, an embedded processor or processors of other programmable data processing devices to realize the functions described in the description and diagrams. In particular, a processor or processing apparatus may execute the machine readable instructions. Thus functional modules of the apparatus and devices may be implemented by a processor executing machine readable instructions stored in a memory, or a processor operating in accordance with instructions embedded in logic circuitry. The term ‘processor’ is to be interpreted broadly to include a CPU, processing unit, ASIC, logic unit, or programmable gate array etc. The methods and functional modules may all be performed by a single processor or divided amongst several processors.
Such machine readable instructions may also be stored in a computer readable storage that can guide the computer or other programmable data processing devices to operate in a specific mode.
Such machine readable instructions may also be loaded onto a computer or other programmable data processing devices, so that the computer or other programmable data processing devices perform a series of operations to produce computer-implemented processing, thus the instructions executed on the computer or other programmable devices realize functions specified by flow(s) in the flow charts and/or block(s) in the block diagrams.
Further, the teachings herein may be implemented in the form of a computer software product, the computer software product being stored in a storage medium and comprising a plurality of instructions for making a computer device implement the methods recited in the examples of the present disclosure.
While the method, apparatus and related aspects have been described with reference to certain examples, various modifications, changes, omissions, and substitutions can be made without departing from the spirit of the present disclosure. It is intended, therefore, that the method, apparatus and related aspects be limited only by the scope of the following claims and their equivalents. It should be noted that the above-mentioned examples illustrate rather than limit what is described herein, and that those skilled in the art will be able to design many alternative implementations without departing from the scope of the appended claims. Features described in relation to one example may be combined with features of another example.
The word “comprising” does not exclude the presence of elements other than those listed in a claim, “a” or “an” does not exclude a plurality, and a single processor or other unit may fulfil the functions of several units recited in the claims.
The features of any dependent claim may be combined with the features of any of the independent claims or other dependent claims.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2021/029716 | 4/28/2021 | WO |
