Diagnostic methods for CIJ printers

Abstract

A computer implemented method comprises receiving log data that comprises one or more of sensor data and event data associated with a continuous inkjet, CIJ, printer; receiving error data indicative of an error on the CIJ printer; determining, in response to receiving the error data, viscosity data (determined based on at least a portion of the log data and indicative of a viscosity of an ink being used in the CIJ printer) and CIJ printer status data determined based on at least a portion of the log data and indicative of a status of the CIJ printer; determining print head status data (indicative of a status of a print head of the CIJ printer) based on the viscosity data and CIJ printer status data; and executing, based on the print head status data, a diagnostic routine on either an electrical system or an ink system of the CIJ printer.

Description

[0001] DIAGNOSTIC METHODS FOR CIJ PRINTERS

[0002] Technical Field

[0003] The present disclosure relates to diagnostic methods and apparatus for a Continuous Inkjet (CIJ) printer.

[0004] Background

[0005] CIJ printers are a type of industrial printer. An industrial printer is a printer that operates in an industrial setting, such as in a warehouse or factory, and is typically used to mark products, packaging or labels as they are transported past the industrial printer on a production line. CIJ printers are complex machines that typically operate uninterrupted for long periods of time and in highly changeable environmental conditions. As such, they can be prone to faults. When an industrial printer, such as a CIJ printer, develops a fault, often the entire production line needs to be halted while the fault is diagnosed and fixed. This can cause undesirable delays in production. Furthermore, owning to their complex nature, it can be difficult and time consuming for a user to determine the cause of the fault of a CIJ printer.

[0006] Summary

[0007] In a first aspect there is provided a computer implemented method comprising, receiving log data, the log data comprising one or more of sensor data and event data associated with a continuous inkjet, CIJ, printer; receiving error data, the error data indicative of an error on the CIJ printer; determining, in response to receiving the error data, viscosity data, the viscosity data determined based on at least a portion of the log data, the viscosity data indicative of a viscosity of an ink being used in the CIJ printer; determining, in response to receiving the error data, CIJ printer status data, the CIJ printer status data determined based on at least a portion of the log data, the CIJ printer status data indicative of a status of the CIJ printer; determining print head status data based on the viscosity data and CIJ printer status data, the print head status data indicative of a status of a print head of the CIJ printer; and executing, based on the print head status data, a diagnostic routine on either an electrical system of the CIJ printer or an ink system of the CIJ printer.

[0008] In this way, the diagnostic routine is guided to checking either the electrical system or the ink system based on the state of the print head. For example, if the error is an EHT trip, and it is determined that the print head is clean, there is likely a fault in the electrical system of the CIJ. If the error is an EHT trip, and it is determined that the print head is dirty , there is likely a fault in the ink system of the CIJ. Determining the status of the print head therefore guides the diagnostic routine in order to determine the cause of the error. Once the cause has been determined, corrective action may be taken, such as sending instructions to a user of the CIJ printer which can be used to correct the issue, or sending computer readable instructions to the CIJ printer so as to automate the corrective action.

[0009] The computer implemented method may be carried out at a remote server. The server may receive the log data and error data from the CIJ printer over a network, such as the internet.

[0010] The sensor data may be captured by one or more sensors of the CIJ printer, the sensors configured to measure a physical phenomenon associated with the CIJ printer and / or components of the CIJ printer.

[0011] The event data may comprise recorded events, such as when the CIJ printer is turned on, or changes between operational modes.

[0012] The error data may be data indicating that an EHT trip occurred at the CIJ printer.

[0013] The viscosity data may comprise any one or more of; a warning output by the CIJ printer, the warning related to a viscosity of ink; a comparison between the viscosity of ink as measured by the CIJ printer and a target viscosity; phasing data recorded by the CIJ printer; temperature data of a viscometer of the CIJ printer; air filter data of an air filter of the CIJ printer, the air filter data indicating a lifetime of the air filter; and make up fluid data comprising the quantity of make up fluid in a cartridge and / or tank of the CIJ printer. The CIJ printer status data may comprise any one or more of: a count of total drops printed by the CIJ printer; EHT trip data; and jet skew data, the jet skew indicating the presence of a jet skew event in the CIJ printer.

[0014] The count of total drops printed may be the total drops generated by the CIJ printer since the print head was cleaned. The EHT trip data may comprise EHT trip %. The EHT trip data may by a determination indicating that the EHT trip % (e.g. the % of the trip current) meets a threshold in a given time period. For example, it may be determined that the EHT trip % is > 75% for 10 minutes before the error occurred. The jet skew data may indicate that an ink stream exiting the CIJ printer became skewed (deviated) from its normal path.

[0015] The computer implemented method may further comprise: determining, in response to receiving the error data, start up data, the start up data determined based on at least a portion of the log data, the start up data indicative of a start up condition of the CIJ printer; and determining the print head status data based on the viscosity data, CIJ printer status data and start up data.

[0016] The start up data may comprise any one or more of data indicating that the CIJ printer started a printing operation with no make-up cartridge installed; data indicating that the CIJ printer started a printing operation with a level of make-up fluid in an installed make-up cartridge being below a threshold value; and data indicating that a mixer tank level exceeds a threshold value.

[0017] The computer implemented method may further comprise determining, in response to receiving the error data, frequency data, the frequency data determined based on at least a portion of the log data, the frequency data comprising one or more of an operational frequency of the CIJ printer; and data relating to the frequency of EHT trips in the CIJ printer; and determining the print head status data based on the viscosity data, CIJ printer status data, start up data and frequency data.

[0018] The operational frequency may be the frequency of ink drop generation in Hz.

[0019] Determining print head status data may comprise processing the viscosity data and CIJ printer status data using a truth table, the truth table comprising one or more truth statements. Where start up data and frequency data are determined, these too may be processed using a truth table.

[0020] Determining print head status data may comprise performing a first level test, the first level test comprising processing each of the viscosity data and CIJ printer status data using the truth table to determine a first level output, and determining the print head status based on the first level output.

[0021] The truth table may comprise a series of truth statements relating to the viscosity data and the CIJ status data. The first level output is the output of a series of truth statements in the truth table. The first level output may therefore be in the form of a binary’ series of data values, such as true or false, 1 or 0, etc., indicating whether a given truth statement was satisfied.

[0022] Determining the print head status data may further comprise performing a second level test, the second level test comprising processing the first level output by applying one or more truth statements to the first level output to obtain a second level output, and determining the print head status based on the second level output.

[0023] For example, a second level test may take as input multiple first level outputs (such as a binary7series of data values, such as true or false) and process these to output a second level output, such as a single true or false output. This may be combined with a first level output and / or another second level output to determine the print head status data.

[0024] Determining the print head status data may further comprise performing a third level test, the third level test comprising processing the second level output by applying one or more truth statements to the second level output to obtain a third level output, and determining the print head status based on the third level output.

[0025] For example, the second level output may be processed with another output of a test (such as another first or second level test) to obtain the third level output. For example, a second level output may be processed with a first level output using the truth table to determine a third level output. The computer implemented method may further comprise using a binary regression model to estimate a probability of at least one truth statement being true and converting the probability to a binary response for output.

[0026] The print head status data may comprise data indicating whether the print head is clean or dirty.

[0027] Executing, based on the print head status data, the diagnostic routine on either the electrical system of the CIJ printer or the ink system of the CIJ printer may comprise: executing the diagnostic routine on the electrical system if the print head status data indicates that the print head is clean; or executing the diagnostic routine on the ink system if the print head status data indicates that the print head is dirty .

[0028] The computer implemented method may further comprise: determining, based on an outcome of the execution of the diagnostic routine, corrective action, the corrective action for correcting the error on the CIJ printer.

[0029] The computer implemented method may further comprise sending the corrective action to the CIJ printer, the corrective action configured to cause the CIJ printer to take corrective action to correct the error.

[0030] The computer implemented method may further comprise sending the corrective action to the user of the CIJ printer.

[0031] For example, the corrective action may take the form of instructions that the user can use to correct the error. The instructions may be sent to the user via email, SMS, and the like.

[0032] In a second aspect there is provided a computer implemented method comprising: receiving log data, the log data comprising one or more of sensor data, EHT trip data and event data associated with the CIJ printer; determining, based on the log data, viscosity' data, the viscosity data determined based on at least a portion of the log data, the viscosity data indicative of a viscosity of an ink being used in the CIJ printer; determining, based on the viscosity data and the EHT trip data, a likelihood that the print head is clean. In this way, a likelihood that the print head is clean or dirty is determined based on proxy data. That is, data indirectly related to the print head cleanliness. For example, ink viscosity can have an effect on the cleanliness of the print head, and EHT trip data, such as the frequency of EHT trips provide an indication of print head cleanliness. The combination of viscosity’ data and EHT trip data provides an indication of the printhead cleanliness, negating the need to have separate sensors on the print head to directly measure the print head cleanliness.

[0033] The computer implemented method of the second aspect may be combined with optional features of the computer implemented method of the first aspect.

[0034] In a third aspect there is provided a server comprising: a processor; and a memory’, the memory storing instructions thereon which when executed by the processor, cause the processor to cany' out the method according to any preceding claim.

[0035] The server may be remote from the CIJ printer, e.g. in a different geographical location.

[0036] In a fourth aspect there is provided a computer readable storage medium comprising instructions which, when executed by a computer, cause the computer to cany out the method according to any preceding claim.

[0037] Brief description of drawings

[0038] Figure 1 is a schematic diagram of a system according to the present disclosure;

[0039] Figure 2 is a flow chart of a truth table according to an embodiment of the present disclosure;

[0040] Figure 3 is a flow chart of a method according to an embodiment of the present disclosure; and

[0041] Figure 4 is a schematic diagram of an apparatus configured to cany' out the methods disclosed herein.

[0042] Detailed Description Example implementations may include improved diagnostics of CIJ printers.

[0043] Figure 1 shows a schematic diagram of a system 100. The system 100 comprises at least one CIJ printer 102. The CIJ printer 102 is an industrial printer, which may be operating on a production line (not shown). For example, the CIJ printer 102 may be located at a factory. There may be several CIJ printers 102 located at factory, but just one is shown in Figure 1 for clarity. The system 100 comprises a server 104. The server 104 may be located at a remote site from the CIJ printer 102, such as located in the cloud. The CIJ printer 102 and server 104 are able to communicate with each other over a network 103 in order to send data. The network 103 may be any suitable network, such as the internet. The CIJ printer 102 may connect to the network 103 via one or more intermediate devices (not shown), such as a router, edge computer, cellular phone, smart phone, etc.

[0044] The CIJ printer 102 comprises an electrical system 105, ink system 106, print head 107 and controller 108. The controller 108 comprises a computer processor and is configured to operate the CIJ printer 102. The electrical system 105 comprises, for example, a power supply for the CIJ printer 102. The ink system 106 is configured to provide ink to print head 107. The ink system 106 may comprise one or more mixing tanks for mixing ink and mark-up fluid, ink and make-up fluid cartridges, pumps for transporting ink to the print head 107, etc. The print head 107 is configured to mark substrates that pass the print head 107, such as products on a production line. The print head of a CIJ printer comprises deflection plates (not shown) which deflect charged ink droplets to a desired location as will be well understood by the skilled person.

[0045] The controller 108 is configured to generate log data. The log data captures data relating to the operation of the CIJ printer 102. Such log data may include sensor data and event data associated with the CIJ printer 102. For example, the log data may include details of various events associated with the CIJ printer 102, such as operational modes of the CIJ printer 102, faults and warnings and error codes that are detected by the controller 108, and time stamped sensor readings measured by one or more sensors of the CIJ printer 102. The log data may also comprise other data, such as user set parameter data (e.g.. settings that have been selected by a user). The CIJ printer 102 may have a number of sensors associated with different components of the CIJ printer 102, the sensors configured to measure parameters associated with the component. For example, the ink system 106 may include sensor parameters such as ink pump parameters such as pressure, speed, current, and pump run hours; ink reservoir parameters such as ink type, ink expiry date, fluid level (ml and / or %), print hours remaining, and ink tank temperature; make up reservoir parameters such as make up type, expiry date, makeup vacuum, fluid level (ml and / or %), print hours remaining, and makeup tank temp; viscometer parameters such as target time to empty, actual time to empty, density, viscosity, and fill time; ink quality parameters such as ink conductivity; condenser parameters such as status (on or off), temperature, and vent valve (on or off); filter / damper module parameters such as ink filter pressure drop, serial number, manufacture date, run hours, and replacement date; service module parameters such as flush pump speed, flush pump current, serial number, manufacture date, run hours, replacement date, and information for various service module valves (open, closed, and time open or closed): ink cartridge parameters such as ink type, recommended make up type, serial number, manufacture date, expiry date, cartridge size, fluid level, run elapsed time, time to cartridge replacement, number of cartridge insertions, viscosity coefficient(s), fluid density, modulation algorithm numbers, and cold start algorithm numbers; make up cartridge parameters such as makeup type, serial number, manufacture date, expiry date, cartridge size, fluid level, run elapsed time, time to cartridge replacement, and number of insertions. Other sensor parameters may relate to air filter parameters such as date last replaced, run hours, and replacement date; fume / gas sensors within the printer cabinet; humidity sensors within the printer or for ambient measurement; electrical parameters such as time and date, electronics temperature, HV voltage, HV Current, and the voltage of various other power supplies within the electronics system 105.

[0046] The CIJ printer 102 is configured to send the log data to the server 104 via network 103. The CIJ printer 102 may send the log data when the CIJ printer 102 determines the presence of an error, and / or may periodically send the log data, such as at the end of every print job, or after a predetermined time has elapsed.

[0047] The CIJ printer 102 is further configured to send error data to the server 104 via network 103. The error data may be an indication that the CIJ printer 102 has detected a fault or error, such as an EHT trip. The error data may be sent with the log data. For example, when the CIJ printer 102 detects an error, it may send the current log data at the time of the error along with the error data. The error data and log data can be used by the server 104 to determine a cause of the error and thus determine remedial action to be performed in order to correct the error. For example, on receiving error data, a truth table may be used to process the log data to determine the cause of the error, the truth table comprising a number of logical statements. Each logical statement (e.g. truth statement) can be applied to parts of the log data to determine if the logical statement is satisfied. This may be considered to be a first level test in that it operates directly on the data in the log data. The (or at least a portion of the) outputs of each statement in the first level test may be combined to determine a condition, which may be referred to as performing a second level test. The second level test operates on at least some data that has at least been output by the first level test. The (or at least a portion of the) outputs of each statement in the second level test may be combined to determine a further condition, which may be referred to as performing a third level test. The third level test operates on at least some data that has at least been output by the second level test, but can also include data output from the first level test. The overall logic flow of the truth table and the individual logical statements may be determined empirically, based for example on historical data from CIJ printers 102.

[0048] A common fault on CIJ printers 102 is an extra high tension (EHT) trip. An EHT trip is often caused by build up over time of ink residue on a deflector plate of the print head 107. A build up of ink on a deflector plate can cause a gap between the deflector plate and second deflector plate to reduce, which can then cause a short circuit (know n as an EHT trip). An EHT trip therefore disrupts the electric field between the deflector plates, which affects the deflection of charged ink droplets, leading to an undesirable print result.

[0049] Another common reason for an EHT trip is that there is a problem with the electrical system 105 of the CIJ printer 102. For example, a component of the electrical system 105 may have failed, the electrical system 105 may be suppling incorrect voltages to components of the CIJ printer 102, and / or the operating temperature of the electrical system may be beyond normal limits, etc.

[0050] When an EHT trip occurs, it can be useful to first determine whether the print head 107 is clear or dirty (e.g. determine if there is residual ink on one or both of the deflector plates), in order to guide subsequent analysis. For example, if it is determined that the print head 107 is dirty, it is likely that the cause of the EHT trip was due to a dirty' print head, and the ink system 106 should be checked. If it is determined that the print head 107 is clean, it is likely that the cause of the EHT trip was an electrical issue, and the electrical system 105 of the CIJ printer 102 should be checked.

[0051] When performing remote servicing, such as by server 104, it is not always possible to automatically determine if a print head is clean or dirty. However, it has been found that it is possible to determine a likelihood that the print head is clean or dirty based on data contained within the log data 102. In particular, viscosity data indicative of a viscosity of an ink being used in the CIJ printer 102, and CIJ printer status data indicative of a status of the CIJ printer 102 can be used to determine a likelihood that the print head is clean or dirty.

[0052] The viscosity data may be determined by the server 104 from the log data. For example, any data within the log data that relates to ink viscosity may be used to determine viscosity data. The viscosity data may comprise a warning output by the controller 108, recorded in the log data, the warning related to the viscosity of the ink. For example, the controller 108 may detect that the ink viscosity is too low or too high, or may detect that there is no make-up fluid present (such as no make-up cartridge installed), or may detect that there is a low level of make-up fluid present in, for example a make-up cartridge or mixing tank. When any of these conditions is detected, the controller 108 may output a warning, recorded in the log data.

[0053] The viscosity data may comprise a comparison between a current viscosity as measured by the controller 108 at the time of the fault and a target viscosity to determine if the current viscosity matches the target viscosity. The current viscosity may be recorded in the log data. The target viscosity may also be recorded in the log data, or may be known to the server 104. The viscosity data may comprise phasing data recorded by the controller 108. For example, the phasing data may indicate that a good phase was achieved. The viscosity data may comprise temperature data of a viscometer of the CIJ printer 102. For example, viscosity data may comprise a comparison between a recorded temperature of the viscometer at the time of the error and a normal working range to determine if the recorded temperature is within the normal working range. The viscositydata may comprise data indicating the lifetime of an air filter in the CIJ printer 102 at the time of the error. The viscosity data may comprise data relating to a make-up fluid, such as whether a make-up cartridge was installed or the level of make-up fluid exceeds a predetermined quantity. The CIJ printer status data may be determined by the server 104 from the log data. For example, any data within the log data that relates to the status of the CIJ printer 102 may be used. The CIJ printer status data may comprise a count of total drops printed by the CIJ printer 102, since the print head was last cleaned, at the time of the error. The CIJ printer status data may comprise EHT trip data, indicating previous EHT trip events associated with the CIJ printer 102. For example, the EHT trip data may comprise data relating to EHT trip % (e.g. a percentage of the trip current at a deflector plate that when exceeded causes an EHT trip). The CIJ printer status data may comprise jet skew data, the jet skew indicating the presence of a recent jet skew event in the CIJ printer 102, such as an undesirable deviation of an ink stream from the print head 107.

[0054] Based on both the viscosity data and the CIJ printer status data, the server 104 determines print head status data indicative of a status of the print head 107 of the CIJ printer 102. The status of the print head 107 may comprise a likelihood that the print head 107 is clean or is dirty. The combination of both the viscosity data and CIJ printer status data allow the status of the print head (whether it is clean or dirty ) to be indirectly determined. In this way, the viscosity' data and CIJ printer status data may be thought of as proxies for determining the status of the print head 107.

[0055] The viscosity data and CIJ printer status data may be processed by the server 104 using a truth table (such as that show n in table 1 below). For example, the viscosity data may be processed by applying truth statements to the viscosity data (such as tests VI, V2, V3, V4 and V5 in Figure 2) and the CIJ printer status data may be processed by applying truth statements to the CIJ printer status data (such as tests PD, EP and JetSkew in Figure 2). Once processed with the truth table by applying truth statements, the final output will be a binary value indicating whether the print head 107 is likely clean or likely dirty.

[0056] For example, if there are no issues indicated by the viscosity data (i.e. there are likely no issue w ith viscosity), the overall output of the truth statements for the viscosity data may be “true” (such as output of test D in Figure 2), whereas if there is likely an issue with viscosity, the overall output of the truth statements for the viscosity data may be “false”. Similarly, if there are no issues indicated by any of the CIJ printer status data, the output of the logical statements (such as tests PD, EP and JetSkew in Figure 2) for the CIJ printer status data may all be true, whereas if there is likely an issue with the CIJ printer status, the output of the truth statements for at least one of the CIJ printer status data may be “false”.

[0057] The outputs of the truth statements applied to the viscosity’ data may be combined w ith at least one of the outputs of the truth statements applied to the CIJ printer status data in order to determine the print head status data (such as test K in Figure 2). For example, if all outputs are true, the combination may also be true, and it may be determined that the print head is likely clean. If one of the outputs is false, the combination may be false and it may be determined that the print head is likely dirty.

[0058] As well as viscosity data and CIJ printer status data, additional data may be used in the determination of the status of the print head. For example, start up data indicative of a condition of the CIJ printer 102 when the printer is started may be used. The start up data may indicate whether a clean start or dirty start took place when the CIJ printer 102 was started. CIJ printers are typically started with a clean start, where excess make-up fluid is initially used to clean the print head 107. However, if there is insufficient make-up fluid, a clean start may not be performed (e.g. the excess make-up fluid may not initially be used to clean the print head). Start up data may indicate that the CIJ printer 102 started a printing operation with no make-up cartridge installed, that the CIJ printer started a printing operation with a level of make-up in an installed make-up cartridge being below a threshold value and / or that a mixer tank level exceeds a threshold value.

[0059] The server 104 may determine the start-up data based on at least a portion of the log data, and may process the start-up data with a truth statements (such as tests N and P in Figure 2). For example, if it is determined that a clean start did not take place due to there being no or low' make-up fluid, for example, the truth table may output a value indicative of a dirty start. The output of the truth statements applied to start-up data can be combined with the outputs of the truth statements applied to the viscosity data and the CIJ printer status data to determine the status of the print head (such as test R in Figure 2).

[0060] Further data can be used in determining the status of the print head, the further data derived from the log data. For example, EHT trip frequency data may be determined. If there is a relatively short time between the CIJ printer 102 starting a print job and an EHT trip, such as less than 1 minute, this can indicate that there is an electrical problem. The server 104 may process the EHT trip frequency data with one or more truth statements (such as test O in figure 2), the output of the which can be used in combination with the viscosity data, CIJ printer status data and start-up data to determine the likelihood that the print head is either clean or dirty (such as test R and test M in figure 2). Other data that may be used in determining the status of the print head may be operational frequency data indicating the frequency of drop generation. If the operational frequency is too high, such as greater than 100 KHz, this will likely cause build up of ink residue around the print head 107. The server 104 may process the operational frequency data with one or more truth statements (such as test Q in Figure 2). The output may indicate whether the operational frequency is above or below a threshold, such as 1000 KHz. The operational frequency data can be used in combination with the viscosity data, CIJ printer status data, startup data and EHT trip frequency data to determine the likelihood that the print head is either clean or dirty (such as test R or test M in Figure 2).

[0061] When the print head status is determined, an appropriate course of action can be determined. If it is determined that the print head 107 is likely clean (e.g. there is not significant build up of residual ink around the deflector plates), the issue that was the cause of the generation of the error is likely not related to the ink system 1 6, but is more likely related to the electrical system 105. As such, on determination that the print head 107 is likely clean, a diagnostic routine is executed on the electrical system 105 of the CIJ printer 102. However, if it is determined that the print head 107 is likely dirty (e.g. there is significant build up of residual ink around the deflector plates), the issue that was the cause of the generation of the error is likely not related to the electrical system 105, but is more likely related to the ink system 106. As such, on determination that the print head 107 is likely dirty, a diagnostic routine is executed on the ink system 106 of the CIJ printer 102.

[0062] Once the issue has been diagnosed, corrective action may be taken by the server 104, such as sending instructions to a user of the CIJ printer 102 which instruct the user how to correct the issue, or sending computer readable instructions to the CIJ printer 102 so as to automate the corrective action.

[0063] The user of the CIJ printer 102 may be able to view the instructions on how to take corrective action on a dashboard of a computer screen associated with the CIJ printer 102. The dashboard may display 1) a summary of the diagnostic outcome and corrective action that needs to be taken in order to remedy the issue. The dashboard may provide a link (e.g. hyperlink, QR code) which, when selected by the user, provides further details, such as the individual results of the diagnostic tests. The dashboard may also provide a link (e.g. hyperlink. QR code) to a targeted knowledge base article providing detailed corrective action steps. In other examples, the corrective action may instead be sent in emails or SMS messages to the user. The emails / SMS may comprise a link (e.g. hyperlink, QR code) which, when selected, provide further details of how to correct the error.

[0064] A specific example of a truth table that can be used to determine if a print head of a is likely clean or likely dirty when the error data indicates that there has been an EHT trip is shown in Table 1 below, and depicted as a flow chart in Figure 2. Table 1 sets out a list of tests, where each test lists the parameter being evaluated, the evaluation criteria used to evaluate the parameter (where appropriate description is provided in italics), and the possible outputs (where if the evaluation criteria is positive, the output is true and if the evaluation criteria is negative, the output is false). The specific error codes in Table 1 are those used in Videojet CIJ printer models 1580. 1880, 1580-C, 1580+, 1880+, 1880UHS, and 1880HR. OFD in table 1 refers to an on fault diagnostic file, which could be the log data described above, or could be sent separate to the log data, such as when an error is detected at the CIJ printer 102.

[0065]

[0066] Table 1

[0067] It will be appreciated that not all tests shown in Table 1 are required. For example, it may not be necessary' to carry out all five subtests, VI, V2, V3, V4 and V5. In some cases, only one or two may be carried out. such as VI and V2. Where fewer subtests are carried out, any dependent tests are modified. For example, if only VI is carried out, then test D is based only on the output ofVl. As noted above, if the print head 107 is determined to be likely clean, a diagnostic routine is executed on the electrical system 105, whereas if the print head is determined to be likely dirty, a diagnostic routine is executed on the ink system 106. The diagnostic routine may be any suitable diagnostic routine. The diagnostic routine may involve using truth tables. For example, a specific example of a truth table that can be used to check the electrical system is show n in Table 2 below;

[0068] Table 2

[0069] A specific example of a truth table that can be used to check the ink system is shown in Table 3 below.

[0070] Table 3

[0071] The subtests in each of the tables can be used to help identify which components of the electrical system or ink system are potentially problematic, thus assisting with the diagnosis of the error.

[0072] While it has been described that truth statements are applied to process the log data, other methods may be used. For example, one or more (or all) of the truth statements could be replaced with a probit, logit, or other binary regression system that could estimate the likelihood of the statement being true and a threshold set to convert the probability to a binary response. Such regression systems could be automatically updated based on past experiences. For example, feedback provided by a user or technician as to whether a particular diagnosis was correct could be fed back into the regression system in order to retrain the regression system.

[0073] With reference to Figure 3, there is now described a method in accordance with an embodiment of the disclosed subject matter.

[0074] At step SI, log data is received. The log data comprises one or more of sensor data and event data associated with a continuous inkjet, CIJ, printer. The log data may be received by the server 104, having been sent by the CIJ printer 102.

[0075] At step S2, error data is received, the error data indicative of an error on the CIJ printer. For example, the CIJ printer 102 may have detected an error or fault, and may in response send a notification to the server 104 indicating the error.

[0076] At step S3, and in response to the error data, viscosity data may be determined, the viscosity data determined based on at least a portion of the log data, the viscosity data indicative of a viscosity of an ink being used in the CIJ printer. For example, the server 104 may, in response to receiving the error data, process the log data to determine viscosity data.

[0077] At step S4, and in response to the error data, CIJ printer status data may be determined, the CIJ printer status data determined based on at least a portion of the log data, the CIJ printer status data indicative of a status of the CIJ printer. For example, the server 104 may, in response to receiving the error data, process the log data to determine the CIJ printer status data.

[0078] At step S5, print head status data is determined based on the viscosity’ data and CIJ printer status data, the print head status data indicative of a status of a print head of the CIJ printer. For example, the server 104 may process the viscosity data and the CIJ printer status data using one or more truth statements in order to determine print head status data. At step S6, and based on the print head status data, a diagnostic routine is executed on either an electrical system of the CI J printer or an ink system of the CI J printer. For example, the server 104 selects which diagnostic routine to execute based on the determined print head status data. If the print head is likely dirty, the server 104 executes a diagnostic routine on the ink system. If the print head is likely clean, the server 104 executes a diagnostic routine on the electrical system.

[0079] An example computing device 400 is shown in more detail in Figure 4. The computing device 400 may be used in the server 104 and / or the controller 108. The computing device comprises a processor 401 which is configured to read and execute instructions stored in a volatile memon 402 which takes the form of a random access memory. The volatile memory 402 stores instructions for execution by the processor 201 and data used by those instructions.

[0080] The computing device 400 further comprises non-volatile storage in the form of a hard disc drive 403. The computing device 400 further comprises an I / O interface 404 to which are connected peripheral devices used in connection with the computing device 400. In the example shown, a display 405 is connected to the I / O interface 404 to display output from the computing device 400. Alternatively or additionally, separate input devices may be also connected to the I / O interface 404, such as a mouse and / or keyboard 406. A network interface 407 allows the computing device 400 to be connected to an appropriate computer network, such as network 103, so as to receive and transmit data from and to other computing devices. The processor 401. volatile memory 402, hard disc drive 403, I / O interface 404, and network interface 407, are connected together by a bus 408.

[0081] It will be appreciated that embodiments disclosed herein can be implemented in any convenient form. For example, embodiments disclosed herein may be implemented by appropriate computer programs which may be carried on appropriate carrier media which may be tangible carrier media (e.g. disks) or intangible carrier media (e.g. communications signals). Embodiments disclosed herein may also be implemented using suitable apparatus which may take the form of programmable computers running computer programs arranged to implement the embodiments disclosed herein. Embodiments of the subject matter and the operations described in this specification can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware. Embodiments of the subject matter described in this specification can be implemented as one or more computer programs, i.e., one or more modules of computer program instructions, encoded on computer storage medium for execution by, or to control the operation of, data processing apparatus. Alternatively or in addition, the program instructions can be encoded on an artificially-generated propagated signal, e.g., a machine-generated electrical, optical, or electromagnetic signal, that is generated to encode information for transmission to suitable receiver apparatus for execution by a data processing apparatus. A computer storage medium can be, or be included in, a computer-readable storage device, a computer-readable storage substrate, a random or serial access memoiy array or device, or a combination of one or more of them. Moreover, while a computer storage medium is not a propagated signal, a computer storage medium can be a source or destination of computer program instructions encoded in an artificially-generated propagated signal. The computer storage medium can also be, or be included in, one or more separate physical components or media (e.g., multiple CDs, disks, or other storage devices).

[0082] The operations described in this specification can be implemented as operations performed by a processor on data stored on one or more computer-readable storage devices or received from other sources.

[0083] The term “processor’7encompasses all kinds of apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, a system on a chip, or multiple ones, or combinations, of the foregoing. The apparatus can include special purpose reprogrammable logic circuitry', e.g., an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit). The apparatus can also include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, a cross-platform runtime environment, a virtual machine, or a combination of one or more of them. The apparatus and execution environment can realize various different computing model infrastructures, such as web services, distributed computing and grid computing infrastructures. Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. Devices suitable for storing computer program instructions and data include all forms of computer-readable media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry and fiber-optic platform for faster data transfer remotely.

[0084] To provide for interaction with a user, embodiments of the subject matter described in this specification can be implemented on a computer having a display device, e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor including audio, for displaying information (e.g. an indication and / or alert) to the user. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback, e.g., visual feedback, auditory feedback, or tactile feedback.

[0085] Although the disclosure has been described in terms of preferred embodiments as set forth above, it should be understood that these embodiments are illustrative only and that the claims are not limited to those embodiments. The skilled person will be able to make modifications and alternatives in view of the disclosure which are contemplated as falling within the scope of the appended claims. Each feature disclosed or illustrated in the present specification may be incorporated in the disclosure, whether alone or in any appropriate combination with any other feature disclosed or illustrated herein.

Claims

CLAIMS:

1. A computer implemented method comprising: receiving log data, the log data comprising one or more of sensor data and event data associated with a continuous inkjet, CI J, printer; receiving error data, the error data indicative of an error on the CIJ printer; determining, in response to receiving the error data, viscosity7data, the viscosity data determined based on at least a portion of the log data, the viscosity7data indicative of a viscosity of an ink being used in the CIJ printer; determining, in response to receiving the error data, CIJ printer status data, the CIJ printer status data determined based on at least a portion of the log data, the CIJ printer status data indicative of a status of the CIJ printer; determining print head status data based on the viscosity data and CIJ printer status data, the print head status data indicative of a status of a print head of the CIJ printer; and executing, based on the print head status data, a diagnostic routine on either an electrical system of the CIJ printer or an ink system of the CIJ printer.

2. The computer implemented method according to claim 1, wherein the error data is data indicating that an EHT trip occurred at the CIJ printer.

3. The computer implemented method according to claims 1 or 2, wherein the viscosity data comprises any one or more of: a warning output by the CIJ printer, the warning related to a viscosity7of ink; a comparison between the viscosity7of ink as measured by the CIJ printer and a target viscosity; phasing data recorded by the CIJ pnnter; temperature data of a viscometer of the CIJ printer; air filter data of an air filter of the CIJ printer, the air filter data indicating a lifetime of the air filter; and make up fluid data comprising the quantity of make up fluid in a cartridge and / or tank of the CIJ printer.

4. The computer implemented method according to claims 1, 2, or 3, wherein the CIJ printer status data comprises any one or more of: a count of total drops printed by the CIJ printer;EHT trip data; and jet skew data, the jet skew indicating the presence of ajet skew event in the CIJ printer.

5. The computer implemented method according to any preceding claim, further comprising: determining, in response to receiving the error data, start up data, the start up data determined based on at least a portion of the log data, the start up data indicative of a start up condition of the CIJ printer; and determining the print head status data based on the viscosity data, CIJ printer status data and start up data.

6. The computer implemented method according to claim 5, wherein the start up data comprises any one or more of: data indicating that the CIJ printer started a printing operation with no make-up cartridge installed; data indicating that the CIJ printer started a printing operation with a level of make-up fluid in an installed make-up cartridge being below a threshold value; and data indicating that a mixer tank level exceeds a threshold value.

7. The computer implemented computer implemented method according to claim 5 or 6, further comprising: determining, in response to receiving the error data, frequency data, the frequency data determined based on at least a portion of the log data, the frequency data comprising one or more of: an operational frequency of the CIJ printer; and data relating to the frequency of EHT trips in the CIJ printer; determining the print head status data based on the viscosity data, CIJ printer status data, start up data and frequency data.

8. The computer implemented method according to any preceding claim, wherein determining print head status data comprises processing the viscosity data and CIJ printer status data using a truth table, the truth table comprising one or more truth statements.

9. The computer implemented method according to claim 8, wherein determining print head status data comprises performing a first level test, the first level test comprising processing each of the viscosity data and CIJ printer status data using the truth table to determine a first level output, and determining the print head status based on the first level output.

10. The computer implemented method according to claim 9, wherein determining the print head status data further comprises performing a second level test, the second level test comprising processing the first level output by applying one or more truth statements to the first level output to obtain a second level output, and determining the print head status based on the second level output.

11. The computer implemented method according to claim 10, wherein determining the print head status data further comprises performing a third level test, the third level test comprising processing the second level output by applying one or more truth statements to the second level output to obtain a third level output, and determining the print head status based on the third level output.

12. The computer implemented method according to any of claims 8 to 11, further comprising using a binary regression model to estimate a probability of at least one truth statement being true and converting the probability to a binary response for output.

13. The computer implemented method according to any preceding claim, wherein the print head status data comprises data indicating whether the print head is clean or dirty.

14. The computer implemented method according to claim 13, wherein executing, based on the print head status data, the diagnostic routine on either the electrical system of the CIJ printer or the ink system of the CIJ printer, comprises: executing the diagnostic routine on the electrical system if the print head status data indicates that the print head is clean; orexecuting the diagnostic routine on the ink system if the print head status data indicates that the print head is di rt .

15. The computer implemented method according to any preceding claim, the method further comprising: determining, based on an outcome of the execution of the diagnostic routine, corrective action, the corrective action for correcting the error on the CIJ printer.

16. The computer implemented method according to claim 15, further comprising: sending the corrective action to the CIJ printer, the corrective action configured to cause the CIJ printer to take corrective action to correct the error.

17. The computer implemented method according to claim 15, further comprising: sending the corrective action to the user of the CIJ printer.

18. A computer implemented method comprising: receiving log data, the log data comprising one or more of sensor data, EHT trip data and event data associated with the CIJ printer; determining, based on the log data, viscosity data, the viscosity data determined based on at least a portion of the log data, the viscosity data indicative of a viscosity of an ink being used in the CIJ printer; and determining, based on the viscosity’ data and the EHT trip data, a likelihood that the print head is clean.

19. A sen' er comprising: a processor; and a memory, the memory storing instructions thereon which when executed by the processor, cause the processor to carry out the computer implemented method according to any preceding claim.

20. A computer readable storage medium comprising instructions which, when executed by a computer, cause the computer to carry out the computer implemented method according to any of claims 1 to 18.

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