Troubleshooting in continuous inkjet printers

Abstract

A system (93) monitors the split phase of an electrostatically deflected continuous inkjet printer to identify phase instabilities that may be caused by partial blockage of the jet forming device (17). It ignores alternations between adjacent phase positions and brief, non-repeating phase interruptions. Preferably, it ignores phase changes caused by variations in other printer operating parameters, such as changes in ink pressure. Monitoring can be performed in the printer (99) or in external systems (93), (95).

Description

Technical Field

[0001] This invention relates to a monitoring system and method for an electrostatically deflected continuous inkjet printer, such as an industrial printer adapted to print on a series of objects transported on a conveyor belt in an industrial filling, packaging, or processing line. Typically, the objects are products such as finished goods or packaged food, and the printer is used to print product and batch information, "use-by" dates, etc. The invention also relates to a procedure for implementing the monitoring method. Background Technology

[0002] In the operation of an electrostatic deflection continuous inkjet printer, a continuous jet of ink droplets is formed at the printhead by allowing pressurized ink to exit through a small orifice from the jet forming apparatus (printhead). As the ink jet exits the printhead through the jet forming orifice, it forms a continuous stream of ink, but breaks into droplets after traveling a short distance. The printhead includes an electrode arrangement to capture charge on some or all of the ink droplets and generate an electrostatic field to deflect the charged droplets. Typically, the electrode arrangement includes charging electrodes; the ink is conductive and will charge the droplets through the influence of the voltage on the charging electrodes. The charged droplets are typically deflected by an electrostatic field generated by a pair of deflecting electrodes. The droplets are deflected in flight so that only some droplets are used for printing. Droplets used for printing are not required to be captured by a gutter and are typically returned to the ink cartridge within the printer body. The printhead is typically connected to the printer body via a flexible conduit (sometimes called an umbilical cord), which is typically 1 to 6 meters long. The printhead can be detached from the printer body. Typically, the printhead and umbilical cord are provided as a printhead assembly, which can be attached to and detached from the printer body.

[0003] Pressure vibrations are applied to the ink before it leaves the printhead to form an inkjet. This controls the way the jet breaks into droplets. To ensure proper charge capture on the droplets, it is important to change the voltage on the charging electrodes at the correct phase position relative to the separation of the droplet from the unsplit portion of the inkjet. Therefore, electrostatic deflection continuous inkjet printers typically perform repeated checks on the phase position of the jet splitting into droplets. This phase position (sometimes called the split phase) is usually measured relative to the waveform of the applied pressure vibrations.

[0004] WO 89 / 03768 describes various aspects of the design and operation of an electrostatic deflection continuous inkjet printer. It describes a sequence of valves in the ink system that initiates ink jetting after the ink is pressurized by the ink pump, allowing the valves to be set to a state that allows ink to form. The printer then attempts to determine the time of flight of the ink jet (which provides a measure of the ink jet's speed) and the split phase of the ink jet. If it fails to determine these, the printer performs a routine to draw in air through the jet-forming nozzles, assuming that the nozzles may be clogged.

[0005] US 2016 / 0098234 discloses a system for remotely servicing industrial printers such as continuous inkjet printers. Sensor measurements (along with other data) are sent from the printer to a service center. US 2016 / 0098234 lists a large number of sensor parameters that can be sent, including selected phase, phase change rate, profile, and phase threshold. Based on the sensor data and other data, the system at the service center is configured to issue faults or warnings when appropriate. The system can receive sensor data and other data from a large number of printers and can use historical data to determine the correlation between data such as environmental data and fault data. A long list of examples of faults and warnings is provided. It is also suggested that sensor data can be used to predict potential faults or other malfunctions. For example, if the pump speed is changing over time, it could indicate that the pump is wearing out and may fail, or historical data could indicate that if the pressure drop across the filter reaches a certain point, the printer will fail 99% of the time per week. A table of example predictive faults is given, where one entry gives "phase change rate" as sensor data and "split instability" as the corresponding potential fault. Summary of the Invention

[0006] In embodiments of the invention, a monitoring system monitors the split phase of an electrostatically deflected continuous inkjet printer to identify phase instabilities that may be caused by partial blockage of the jet forming apparatus. Preferably, it ignores alternating and brief, non-repeating phase interruptions between adjacent phase positions. Preferably, it ignores or compensates for phase changes caused by printer operation (such as adding solvent to the ink) or by changes in other printer parameters (such as changes in ink pressure). Monitoring can be performed in the printer or in an external system.

[0007] One aspect of the invention provides a phase stability monitoring system for an electrostatically deflected continuous inkjet printer, which receives printer data and is capable of determining from the printer data phase data that indicates: (a) which of a set of possible phase positions comprises the split phase of the printer's inkjet output at each analysis time in a series of analysis times, and / or (b) the change in the split phase of the inkjet output from one phase position to another among the possible phase positions; analyzing the phase data (optionally together with further data related to printer operation, such as data indicating another operating parameter of the printer (such as ink pressure or changes in ink pressure downstream of the ink pump or other ink pressurization components)) to determine whether the split phase is stable or unstable. Preferably, the analysis does not use instantaneous phase change rates and not only uses average phase change rates (phase change over a time period divided by the length of the time period). Preferably, if the system determines that the split phase is unstable, it outputs a diagnostic conclusion that the printer may have a partially clogged jet forming device and / or recommendations for possible actions to clean and / or unblock the jet forming device.

[0008] Printer data can only provide phase information to the monitoring system when there is a change in the split phase of the inkjet from one possible phase position to another. However, such data allows the monitoring system to determine at each analysis time which possible phase position includes the split phase, because as long as no new phase information is received, it can be assumed that the split phase is included in the same possible phase position as before.

[0009] The phase stability monitoring system may be installed in the printer, or it may be installed in a system outside the printer (such as a remote monitoring system operated by a service organization that maintains the printer, for example), or the phase stability monitoring system may be partially installed in the printer and partially installed in an external system.

[0010] Another aspect of the invention provides a phase stability monitoring method comprising analyzing phase data (optionally together with further data relating to printer operation, such as data indicating another operating parameter of the printer, such as ink pressure or changes in ink pressure downstream of the ink pump or other ink pressurization components)) to determine whether the split phase is stable or unstable, the phase data being: (a) indicating which of a set of possible phase positions comprises the split phase of the printer's inkjet at each analysis time in a series of analysis times, and / or (b) indicating the change of the split phase of the inkjet from one phase position to another among the possible phase positions. Preferably, the analysis does not use instantaneous phase change rates and not merely average phase change rates (phase change over a time period divided by the length of the time period). Preferably, the method includes, in the case that the split phase is determined to be unstable, outputting a diagnostic conclusion that the printer may have a partially clogged jet forming device and / or recommendations for actions that may clean and / or unblock the jet forming device.

[0011] The method can be executed in the printer, or it can be executed in a system outside the printer (such as a remote monitoring system operated by, for example, a service organization that maintains the printer), or it can be executed partly in the printer and partly in an external system.

[0012] If diagnostic results and / or recommendations are output at the printer, it may be accompanied by the transmission of messages to remote devices, such as push notifications or SMS to mobile phones. This allows the printer operator to receive alerts even if they are not at the printer when the diagnostic results and / or recommendations are output.

[0013] If diagnostic conclusions and / or recommendations are output from a system external to the printer (such as a remote monitoring system), it may be accompanied by the automatic transmission of messages to the operator or other people in the organization using the printer. Alternatively, diagnostic conclusions and / or recommendations may only be output from the system, and the person operating the system in the organization can then contact the operator, another person in the user organization, and / or take other actions. This allows the operating system's service organization to provide a service response that may take into account other factors, such as the history of problems with the printer or the user organization's printers. Personnel operating the operating system in the organization can contact the appropriate person personally (such as by telephone call) if it is deemed more likely to lead to appropriate corrective action.

[0014] In electrostatic deflection continuous inkjet printers, split phase is typically detected as one of a predetermined number of possible positions, each of which covers a corresponding portion of a 360° phase period. For example, there may be 16 possible phase positions (such that the phase position can be represented by a 4-bit binary number), each of which covers 22.5° of the phase period.

[0015] Because phase data involves each analysis time in a series of analysis times, and which possible phase positions include the split phase of the printer's inkjet and / or the change of the split phase from one possible phase position to another, it is impossible to determine the instantaneous rate of change. The average rate of change (phase change over a time period divided by the length of that time period) is not a useful measure, at least when considered alone, because the average taken over very short time periods (e.g., five seconds or less) cannot distinguish between unstable split phases and normal changes in the split phase, while the average taken over longer time periods tends to be small because the phase cannot change indefinitely in the same direction, thus the change over longer time periods does not reflect the extent of phase changes that may have occurred during that period. Therefore, preferably, the analysis does not use the rate of change of phase alone, and may not use it at all.

[0016] Preferably, the analysis not only uses the frequency of phase change, but may not use the frequency of phase change at all.

[0017] There are various ways to analyze data to determine whether a split phase is stable or unstable. The analysis may use at least one of the following information: (i) the magnitude of the change in split phase between consecutive analysis times (e.g., measured in the number of possible phase positions); (ii) the size of the range of possible phase positions that have been included in the split phase within a set time period (preferably at least 5 seconds, and more preferably at least 10 seconds) or the total number of different possible phase positions; (iii) whether the continuous change of the split phase from one phase position to another within the possible phase positions is in the same direction or in opposite directions; (iv) the average or total number of absolute values ​​of the changes in the split phase within the set time period; (v) the average of the absolute values ​​of the changes in the split phase relative to the number of times the split phase changes from one possible phase position to another within the set time period; and (vi) the frequency (e.g., the number of times the split phase changes within a given time period) that the split phase may use to determine its frequency of change, without considering the direction and / or magnitude of each change. In practice, it is generally most useful to use at least one of the following information in analytical methods used to determine whether a split phase is unstable: (a) the number of possible phase positions or the magnitude of the change in split phase from one analytical time to the next, expressed in terms of phase angle; (b) the range of change in split phase within a given time period; or (c) whether the successive changes in phase are in the same direction as each other.

[0018] Typically, electrostatic deflection continuous inkjet printers include components for pressurizing ink (usually an ink pump), and a jet forming apparatus is connected to receive the pressurized ink, which can be expelled from the jet forming apparatus by its pressure to form an inkjet. The inkjet will naturally split into droplets. The place where this occurs is the splitting point. The splitting distance (also known as the splitting length) is the distance between the splitting point and a fixed point (usually where the inkjet leaves the jet forming apparatus). Typically, electrostatic deflection continuous inkjet printers include an electrode arrangement for capturing charge on selected ink droplets (also known as charging the droplets) and creating an electrostatic field to deflect the charged droplets. There may be charging electrodes for charging the droplets and deflecting electrodes for forming the electrostatic field. Typically, pressure modulation in the form of vibration or pressure oscillation is applied to the ink before it is expelled from the jet forming apparatus to influence the way the inkjet splits into droplets. The splitting phase of the inkjet is usually defined as the phase of the inkjet splitting into droplets relative to the pressure modulation or the signal used to create the pressure modulation. Monitoring the splitting phase allows for the application of a signal to charge the droplets in a controlled phase relationship with the inkjet's splitting into droplets. It may be important to control this phase relationship to ensure proper charging of successive droplets.

[0019] In a first embodiment, data can be analyzed to determine the frequency of the split phase change over time, regardless of the direction of the change (such that all changes are considered to be in the same direction, and consecutive changes in opposite directions do not reduce the frequency of change). If this frequency of change exceeds a threshold for a longer period than a minimum time interval or repeatedly exceeds the threshold within a given time interval, the split phase is determined to be unstable. Alternatively, the average frequency of change within a given time interval can be determined, and if this average exceeds a threshold, the split phase is determined to be unstable.

[0020] This analysis is based on the expected behavior of the split phase, where, for example, as solvent is lost from the ink and the ink viscosity increases as a result, it may change slowly over time, and when solvent is added to the ink to reduce the viscosity again, it may change more rapidly over a short period of time. If there are large or rapid changes exceeding the changes caused by adding solvent to the ink, or if there are prolonged periods of large or rapid changes that repeat more frequently than the changes caused by continuous solvent addition, it can be concluded that the split phase has become unstable.

[0021] In a second embodiment, data can be analyzed to determine the direction and / or magnitude of changes in phase position. If, within a given time period, there are more than a predetermined number of consecutive changes in the same direction and / or more than a predetermined number of single changes by more than one possible phase position, the split phase is determined to be unstable. Alternatively, the average magnitude of phase changes over a given time period or a given number of phase changes (e.g., the average number of possible phase positions that the phase has moved in each change) is compared to a threshold, and if the threshold is exceeded, the split phase is determined to be unstable. For example, the magnitude of each change in the split phase (measured as the number of possible phase positions that the split phase has changed) can be divided by the total number of changes in the split phase to give the average magnitude of the changes, and this average can be taken over a predetermined number of changes or over a predetermined time period. If this average magnitude of the phase changes exceeds a threshold, the split phase is determined to be unstable.

[0022] This analysis is based on the expected behavior of the split phase, which tends to remain constant over time or change only very slowly. Therefore, if anything other than alternation between adjacent possible phase positions (which can occur if the actual phase of the jet split is very close to the boundary between two possible phase positions) and very slow changes in phase position occur, it can be concluded that the split phase has become unstable.

[0023] Commonly, during normal operation of an electrostatically deflected continuous inkjet printer, factors affecting the splitting phase change only very slowly, apart from changes in viscosity (which changes as solvent evaporates from and is replenished from the ink, and may also change if the temperature at the printer changes). Typically, as viscosity changes, ink pressure changes to keep the inkjet speed constant. Changes in viscosity affect the jet's splitting into droplets, causing changes in the splitting distance, and because this keeps the jet speed constant, it causes a change in the splitting phase. Since changes in viscosity affect the jet's splitting into droplets, it also typically changes the preferred amplitude of the pressure modulation applied to the ink to control its splitting into droplets. Therefore, an automated system used to control the modulation amplitude can respond to changes in viscosity by changing the modulation amplitude. This, in turn, changes the splitting length, and thus the splitting phase. Some printers are set up such that the change in splitting phase directly caused by changes in viscosity and the change in splitting phase caused by changes in modulation amplitude largely cancel each other out, resulting in no significant change in the splitting phase even when viscosity changes. Therefore, the expected behavior of such a printer is that the split phase tends to remain constant over time.

[0024] In a third embodiment, where data is analyzed externally and from a system receiving data from a group of printers including multiple printers, the data is analyzed to compare parameter values ​​from different printers, such as the average rate of phase change over a given time, the range of different phase positions over a given time, or the number of different phase positions over a given time. Printers whose behavior with respect to this parameter is significantly different from the normal behavior of the printer group have unstable split phases. A printer's behavior is considered significantly different if its parameter value is significantly different over a longer period than a set time period, or significantly different more frequently than normal. "Significantly different" can be defined using any convenient statistical analysis. For example, parameter values ​​can be obtained for all printers in the printer group, the standard deviations of those values ​​can be obtained, and values ​​differing from the mean by more than three standard deviations can be considered significantly different. "More frequently than normal" can be defined in a similar manner.

[0025] These embodiments can be viewed as examples of determining split phase instability by comparing the printer's actual behavior (as indicated by phase data) with expected behavior and determining split phase instability if the actual behavior differs from the expected behavior. As noted above, the first embodiment discussed above is based on the expected behavior of the split phase, which may change slowly over time and may change significantly over short periods. The second embodiment discussed above is based on the expected behavior of the split phase, which tends to remain constant over time. The third embodiment discussed above is based on the expected behavior that the printer's behavior will not differ significantly from the normal behavior of the printer group.

[0026] These definitions of expected behavior are simplistic and may lead to the conclusion that the split phase is unstable when it is actually stable. Therefore, as discussed below, a more detailed and accurate definition of expected behavior is preferred. The first and second embodiments discussed above are based on pre-prepared models of the printer's expected behavior. However, a more detailed definition of expected behavior would generally require a more detailed understanding of how the printer operates, as well as a more detailed model based on the expected behavior, and thus require more effort to create. The definition of expected behavior based on the actual observed behavior of all printers in the printer group, as used in the third embodiment discussed above, has the advantage of not requiring any pre-created model of the printer's expected behavior.

[0027] Even the simplistic definition of the expected behavior in the first to third embodiments discussed above could lead to the conclusion that the split phase is unstable in most cases, which is indeed the case. A common cause of unstable split phases is partial blockage of the ink flow at the inkjet head (jet forming device), most commonly at the nozzle. Partial blockage at the inkjet head (especially if it is at the nozzle) can usually be cleared by simple actions that can be taken by the operator.

[0028] Monitoring the split phase allows for the application of a charging signal (typically a signal applied to the charging electrode) to charge the droplets, with a controlled phase relationship to the inkjet splitting into droplets. This enables the charging signal to be changed at the correct phase position relative to the inkjet split to ensure the correct charge level is captured on each droplet. If both the phase monitoring system and the charging signal control system can adequately track changes in the split phase, small and slow changes in the split phase will not cause a significant deterioration in print quality. However, it is difficult for the charging signal control system to adequately respond to large or rapid phase changes. If phase instability is caused by partial clogging at the printhead, any movement, growth, or other change in anything causing the partial clogging can worsen the phase instability, resulting in a loss of consistently acceptable print quality. In extreme cases, clogging can become complete or so severe that an effective jet cannot be formed, thus terminating the printer's ability to print. In such cases, the printer no longer prints correctly, and it is necessary to stop the conveyor belt that carries items through the printer for printing. If this conveyor belt is part of a packaging, filling, or other processing line, it may be necessary to stop the entire line. If such an event occurs in an unplanned manner, it could be extremely disruptive to the operation of the location where the printer is located.

[0029] Since partial blockage at the printhead can often be cleared with simple actions that can be taken by the operator, diagnostic conclusions that a printer outputting with unstable split phases may have a partially blocked jet forming device and / or recommendations for actions that could potentially clean and / or unclog the jet forming device can enable operators to avoid a significant proportion of incidents where the printer stops in order to print correctly. The actions taken by the operator will usually still require stopping the conveyor belt, but this can be done in a planned manner or can be performed when the conveyor belt has already stopped for another reason, and therefore, the interruption will be much less than when the printer stops printing normally. Furthermore, the actions requested by the operator will typically only take a few minutes, and therefore, the interruption caused by it will be brief.

[0030] Furthermore, if a printer fails to print correctly, it's common for the operator or other personnel in the organization using the printer to call a service engineer. Therefore, if the operator takes actions to avoid events where the printer stops printing correctly, a service engineer visit is avoided. This results in cost savings for the service organization that provides the service engineer.

[0031] Depending on how the printer is operated, there are several possible actions that the operator can take that could potentially clear partially clogged jet forming devices. A solvent for diluting the ink can also be used to form the jet, and / or suction can be applied to the interior of the jet forming device such that air is drawn in through the orifice through which the jet normally exits the jet forming device during either or both of the printer's inkjet stop and inkjet start processes. If this is the case, the operator can command the printer to stop inkjet and then restart it. The jet of solvent can dissolve or otherwise help remove blockages. Suction applied to the interior of the jet forming device can remove blockages. Alternatively, the operator can command or perform actions to remove blockages on the exterior of the jet forming device, at the orifice through which the ink normally exits the jet forming device, such as by physical contact (e.g., with a brush) and / or by cleaning with a solvent.

[0032] In one embodiment, the system initially responds to a determination of split phase instability by outputting a first suggestion to the operator to perform a first action (e.g., stop and restart the inkjet). If the split phase instability is still determined within a set period (which can be one to six hours) after the first action has been performed, the system may output a second suggestion, which could be a suggestion to repeat the first action or a suggestion to perform a second action (e.g., clean the printhead). If the split phase instability is still determined within a set period after the second suggested action, the system may output a third suggestion (if one is available), and so on, until either the split phase is determined to be stable, or the rules followed by the system determine that no further action should be suggested to the operator, and instead a service engineer should be dispatched to resolve the phase instability. In this way, a service engineer is dispatched in a timely manner to resolve the problem before the printer becomes unusable, but only when the actions taken by the operator cannot resolve the detected phase instability. This provides better service to printer users and reduces the number of unnecessary service engineer visits.

[0033] A more detailed and accurate model of the printer’s expected behavior can allow for the analysis of phase data (and optionally, other data from the printer) from the printer in a way that more accurately detects instabilities in the split phase caused by partially blocked jet forming devices.

[0034] For example, the method of determining whether a split phase is stable or unstable based on its analytical data preferably does not respond to short, non-repeating phase change periods (especially if the phase change is small during the period) to determine that the split phase is unstable. Preferably, the determination of split phase instability does not respond to a total phase change of no more than 45° and a phase change period lasting no longer than 15 seconds and not repeating within one hour.

[0035] The method of analyzing the data may require averaging the parameter over a time period, or the parameter value exceeding a threshold over the entire given time period or over a specified proportion of a given time period. It can respond to parameters that satisfy criteria indicating phase instability using an incremental counter, and determine phase instability only when the counter reaches a preset value, or it can combine the parameter values ​​over time in some other way to delay the determination of phase instability. Preferably, if a pattern of phase change or other behavior that would lead to the determination of phase instability persists, such a determination will only occur if it lasts for at least one minute (more preferably at least ten minutes), and it may be required that the pattern of phase change or other behavior last for a longer period, such as at least one hour or more.

[0036] This helps avoid making phase instability determinations in response to temporary changes in phase patterns or other behaviors caused by other aspects of printer operation that the printer automatically responds to.

[0037] For example, in most electrostatically deflected continuous inkjet printers, the ink jet only breaks into droplets in the desired manner when pressure modulation of the ink is applied within a specific range. If the pressure modulation amplitude is at the edge of its correct range, it is possible that a small change in ink viscosity could cause a large change in the splitting phase. However, if the printer automatically checks and adjusts the pressure modulation amplitude to keep it away from the edge of its correct range, the pressure modulation amplitude will not remain at the edge of its correct range, and therefore, the large change in the splitting phase will only be temporary. Therefore, a model of the printer's expected behavior could include the expectation that large changes in the temporary periods of the splitting phase that are not sustained are likely caused by temporary errors in the automatically corrected pressure modulation amplitude, and this does not indicate that the splitting phase is unstable.

[0038] The model of the printer's expected behavior may also include the expectation that, when the phase is stable, the detected split phase can alternate between adjacent possible phase positions, and this alternation can occur at any frequency and can be regular or irregular. This behavior is expected because the actual split phase may be very close to the boundary between two possible phase positions in the system used to detect the phase. As a result, very small phase changes that do not indicate instability, or even changes in the detection process without any actual phase change, can cause the detected phase to change from one of the two possible phase positions to the other. Therefore, the way the phase data is analyzed should avoid simply determining phase instability in response to such alternation between adjacent possible phase positions. This can be done in various ways. For example, the analysis can consider the magnitude of each phase change and require a change of more than one possible phase position at a time to determine that the phase is unstable. This can be done by completely ignoring a change of one possible phase position or by requiring the average magnitude of the phase changes to exceed a certain value greater than one possible phase position to determine that the phase is unstable. Alternatively, the analysis can consider the direction of the phase changes and require continuous phase changes in the same direction to determine that the phase is unstable.

[0039] In another embodiment, the size of the range of possible phase positions that already include the split phase within a set time period is determined. If the range of phase positions represents at least 45° of phase (2 possible phase positions if the 360° phase period is divided into 16 possible phase positions), and preferably at least 67.5° of phase (3 possible phase positions if the 360° phase period is divided into 16 possible phase positions), or more phases within the set time period (preferably no more than 5 minutes, and preferably at least 5 seconds, more preferably from 10 seconds to 2 minutes, and most preferably from 15 seconds to 1 minute), then the split phase can be determined to be unstable. Alternatively, a single such event may not be sufficient to determine split phase instability, but if more than a set number of such events exist within the set time period (preferably more than one or two events within a time period of at least one minute and preferably no more than 30 minutes, or a larger number of events within a longer time period, such as more than 5 events within one hour), then the split phase can be determined to be unstable. The time period during which the set number of events occurs should be at least a set factor longer than the time period for measuring the range of phase positions.

[0040] This embodiment is based on the expectation that large changes in the split phase over a short period are unusual, but partially blocked jet forming devices may experience significant phase changes within a short time and tend to repeat this behavior. On the other hand, if the split phase is stable, phase changes of more than 45° within a few minutes are unlikely, and changes of more than one phase position within a few minutes are unlikely to occur frequently. Therefore, phase changes of at least 45°, and particularly 67.5°, within less than five minutes are likely to be caused by partial blockage at the jet forming device, especially if this occurs repeatedly. Severe partial blockage can cause phase changes of up to 360° within 10 to 15 seconds, and this behavior can repeat at intervals of approximately 30 seconds to one minute. Therefore, if determining phase instability requires that the range of phase positions occurring within a set time period represent at least 90° phase (4 possible phase positions if the 360° phase period is divided into 16 possible phase positions), at least 135° phase (6 possible phase positions if the 360° phase period is divided into 16 possible phase positions), or even 180° phase (8 possible phase positions if the 360° phase period is divided into 16 possible phase positions), then severe partial clogging will be detected. However, less severe partial clogging that results in a small phase change can also lead to a decrease in print quality, and therefore, it is preferable, if possible, to base the determination of phase instability on a small phase change.

[0041] The model of expected behavior may also include the expectation that changes in certain printer operations or printer parameters other than the split phase can cause a change in the split phase. For example, adding solvent to ink circulating in the printer will change the ink's viscosity, and this can lead to a change in the split phase. Therefore, data indicating that an operation to add solvent is about to, is, or has just been performed can be used to ignore changes in the split phase that occur within a set period of time (e.g., 1 minute or 5 minutes) after the solvent addition operation.

[0042] As another example, if, for any reason, there is a sudden change in the pressure of the pressurized ink supplied to the jet forming apparatus, this can be expected to cause a corresponding sudden change in the split phase. Sensing the pressure of the pressurized ink is normal in electrostatic deflection continuous inkjet printers, and therefore, analysis can use ink pressure data to prevent the determination of split phase instability in response to the changing pattern of the split phase corresponding to the concurrently occurring pattern of ink pressure changes.

[0043] For example, by experimenting with a specific model of the printer, it might be possible to determine in advance how the split phase changes in response to changes in ink pressure. If a period of pressure change is detected, and if those phase changes match changes expected to be caused by the pressure change, the analysis can ignore phase changes occurring at the same time or any phase changes with a brief time lag after the period of ink pressure change. The analysis can also use phase changes expected to be caused by pressure changes as the expected phase behavior and use the difference from that expected behavior when determining whether the split phase is unstable.

[0044] Simply put, if there exists a period of alternating phase changes not only between adjacent phase positions, and this phase change occurs at the same time as the period of ink pressure change or with a very short time lag after the period of ink pressure change, then this phase change can be considered as possibly caused by the period of pressure change. Therefore, the phase change occurring in that period can be ignored in the analysis determining whether the split phase is unstable. This does not require prior knowledge of how the split phase changes in response to changes in ink pressure.

[0045] Alternatively, the analysis may not attempt to determine whether the pattern of split phase change matches the pattern of ink pressure change, or whether the timing of split phase change matches the timing of ink pressure change. Instead, it may ignore any split phase change that occurs simultaneously with or shortly after the detected ink pressure change.

[0046] Another aspect of the invention provides a monitoring system arranged to: receive printer data from an electrostatically deflected continuous inkjet printer and obtain phase data from the printer data, the phase data being data indicating: (a) which of a set of possible phase positions comprises the split phase of the inkjet from the printer at each analysis time in a series of analysis times; and / or (b) a change in the split phase of the inkjet from one of the possible phase positions to another; and analyze the phase data to determine whether there is partial blockage at the jet forming apparatus of the printer, and if it determines that there is partial blockage at the jet forming apparatus of the printer, output an alarm, the monitoring system being arranged not to output an alarm in response to the alternation of the split phase between adjacent phase positions.

[0047] Another aspect of the invention provides a monitoring system arranged to: receive printer data from an electrostatically deflected continuous inkjet printer and obtain phase data from the printer data, the phase data being data indicating: (a) which of a set of possible phase positions comprises the split phase of the inkjet from the printer at each analysis time in a series of analysis times; and / or (b) the change of the split phase of the inkjet from one of the possible phase positions to another; and to analyze the phase data using at least one of the following: (a) the magnitude of the change of the split phase from one analysis time to the next, expressed in terms of the number of possible phase positions or in terms of phase angle; (b) the range of the split phase variation within a set time period; or (c) whether the continuous changes of phase are in the same direction as each other, to determine whether the split phase is unstable, and if it determines that the split phase is unstable, to output an alarm.

[0048] Another aspect of the invention provides a monitoring system arranged to: receive printer data from an electrostatically deflected continuous inkjet printer and obtain phase data and other data from the printer data, the phase data being data indicating: (a) which of a set of possible phase positions includes the split phase of the inkjet from the printer at each analysis time in a series of analysis times; and / or (b) a change in the split phase of the inkjet from one of the possible phase positions to another, and the other data being data relating to operations other than forming the inkjet at the jet forming apparatus of the printer, and / or data relating to a detected state or a detected change in a state other than the split phase in the printer; and analyzing the phase data to determine whether the split phase is unstable, and if the split phase is determined to be unstable, outputting an alarm, the monitoring system being arranged to not output the alarm if a predetermined condition is indicated by the other data, or to compensate the phase data or analyze the phase data in a manner that compensates for the predicted impact of the predetermined condition on the split phase.

[0049] Another aspect of the present invention provides a monitoring method comprising: receiving printer data from an electrostatic deflection continuous inkjet printer and obtaining phase data from the printer data, the phase data being data indicating: (a) which of a set of possible phase positions comprises the split phase of the inkjet from the printer at each analysis time in a series of analysis times; and / or (b) indicating a change in the split phase of the inkjet from one of the possible phase positions to another; and analyzing the phase data to determine whether there is partial blockage at the jet forming apparatus of the printer, and outputting an alarm in response to determining that there is partial blockage at the jet forming apparatus of the printer, and not outputting an alarm in response to the alternation of the split phase between adjacent phase positions.

[0050] Another aspect of the present invention provides a monitoring method comprising: receiving printer data from an electrostatic deflection continuous inkjet printer and obtaining phase data from the printer data, the phase data being data indicating: (a) which of a set of possible phase positions comprises the split phase of the inkjet of the printer at each analysis time in a series of analysis times; and / or (b) indicating the change of the split phase of the inkjet from one of the possible phase positions to another; and analyzing the phase data using at least one of the following: (a) the magnitude of the change of the split phase from one analysis time to the next, expressed in terms of the number of possible phase positions or in terms of phase angle; (b) the range of change of the split phase within a set time period; or (c) whether the continuous changes of the phase are in the same direction as each other, to determine whether the split phase is unstable, and outputting an alarm in response to determining that the split phase is unstable.

[0051] Another aspect of the present invention provides a monitoring method comprising: receiving printer data from an electrostatic deflection continuous inkjet printer and obtaining phase data and other data from the printer data, the phase data being data indicating: (a) which of a set of possible phase positions comprises the split phase of the inkjet of the printer at each analysis time in a series of analysis times; and / or (b) a change in the split phase of the inkjet from one of the possible phase positions to another, and the other data being data relating to operations other than forming the inkjet at the jet forming apparatus of the printer, and / or data relating to a detected state or a detected change in a state other than the split phase in the printer; and analyzing the phase data to determine whether the split phase is unstable, and if the split phase is determined to be unstable, outputting an alarm, and wherein, if a predetermined condition is indicated by the other data, the alarm is not output, or the phase data is compensated for or the phase data is analyzed in a manner that would compensate for the predicted impact of the predetermined condition on the split phase.

[0052] Further aspects and optional features of the invention are set forth in the appended claims.

[0053] As described above, the printhead may be separable from the printer body, and the term "printer" is used in the description of the features of this invention to cover both the entire printer including the printhead and the printer body excluding the printhead. Attached Figure Description

[0054] Embodiments of the invention will be described by way of non-limiting example with reference to the following figures.

[0055] Figure 1 An inkjet printer embodying the present invention is shown.

[0056] Figure 2 yes Figure 1 A schematic top view of the main components in the printhead of a printer.

[0057] Figure 3 yes Figure 1 A schematic side view of the main components in the printhead of a printer.

[0058] Figure 4 It shows Figure 1 A simplified diagram of the fluid system of a printer.

[0059] Figure 5 schematically shown Figure 1 The main components inside the printer body.

[0060] Figure 6 An arrangement for receiving data sent by one or more printers and monitoring phase stability outside the printer is shown.

[0061] Figure 7 It shows that it can be set to Figure 6 An example of a display in a monitoring system.

[0062] Figure 8 This is a diagram of the main components of the monitoring system.

[0063] Figure 9 This is a flowchart of a process used to monitor the phase data of a printer and output an alarm when it is determined that the split phase is unstable.

[0064] Figure 10 The following are examples of the use of this invention in embodiments of the invention. Figure 9 Modification of the flowchart.

[0065] Figure 11 It shows the Figure 9 The flowchart was modified to avoid responding to phase changes caused by events at other parts of the printer.

[0066] Figure 12 It shows the Figure 9 The flowchart was modified so that split phase instability is only determined when the phase interruption occurs within a set time period.

[0067] Figure 13 It shows the Figure 9 The flowchart was modified so that split phase instability is only determined when a set number of phase interruption events occur within a set time period.

[0068] Figure 14 An embodiment of the invention is shown for use in... Figure 13 The process of updating the analysis parameters in step S2. Detailed Implementation

[0069] Figure 1An electrostatic deflection continuous inkjet printer is illustrated. The printer forms a continuous ink jet and has an electrode arrangement for charging and electrostatically deflecting ink droplets to print a desired pattern. The main fluid and electrical components are housed within the printer body 1. The operator communicates with the printer via a touchscreen display 3. Ink jets are formed within a printhead 5, which also includes an electrode arrangement for charging and deflecting ink droplets, and the printhead 5 is connected to the printer body 1 via a flexible connection 7 called a conduit or umbilical cord. Ink droplets, deflected as needed to create a desired pattern, travel from the printhead 5 and impact the surface 9 of an object 11 being conveyed through the printhead 5 to print the desired pattern on the surface 9 of the object 11. The printhead 5 and the umbilical cord 7 form a printhead assembly that can be detached from the printer body 1.

[0070] The printer is typically an industrial inkjet printer and is suitable for use with a conveyor belt 13 located outside the printer and conveying the object 11 past the printhead for printing. This contrasts with document printers that print on sheet paper, which typically feed the paper themselves rather than using a conveyor belt 13 located outside the printer. The object 11 can be a finished product, such as a bottle or can of beverage, a jar of jam, a serving of ready-to-eat food, or a carton containing multiple individual items. The desired pattern may include product information such as a batch number or "use-by" date. The printer may print onto the object 11 from the side, such that the ink generally travels in a direction across the conveyor belt, or from above, such that the ink generally travels in a direction toward the conveyor belt, or from any other angle. For example, bottles are typically printed from the side, while ready-to-eat foods are typically printed from above. Figure 1 In this case, the printer is set to print from the side and partly from above.

[0071] Figure 2 This is a schematic top view of the main components of printhead 5 in the inkjet area, and Figure 3 This is a schematic side view. The terms "top view" and "side view" refer to the conventional orientation of the printhead as viewed assuming the printer will print onto object 11 from the side, and do not necessarily correspond to the orientation of the printhead in use. Pressurized ink, supplied from the printer body 1 via the umbilical cord 7, is provided to the printhead (jet forming device) 17 via the ink supply line 15. The pressure of the ink is used to form ink jets 19 that are expelled from the printhead 17 through small jet forming orifices. If the printhead 17 receives pressurized ink and any valves in the printhead 17 are in the appropriate position, ink jets 19 are continuously formed. Therefore, this type of inkjet printer is called a continuous inkjet printer, compared to on-demand inkjet printers that only eject ink droplets when printing a single dot.

[0072] Although the inkjet 19 exits the printhead 17 as a continuous stream of ink, it rapidly breaks into separate droplets. The path of the ink jet passes through a groove in the charging electrode 21, which is positioned such that the inkjet 19 breaks into droplets as it passes through the groove of the charging electrode 21. Other arrangements and shapes of the charging electrode 21 are possible, as long as the inkjet 19 is subjected to the electric field of the charging electrode at the location where it breaks into droplets. The ink is conductive, and the printhead 17 is maintained at a constant voltage (typically grounded). Therefore, any voltage applied to the charging electrode 21 will induce charge in the portion of the inkjet 19 that is subjected to the electric field in the groove of the charging electrode 21. As the inkjet 19 breaks into droplets, any such charge is captured on the droplets. In this way, the amount of charge captured on each droplet can be controlled by the voltage on the charging electrode 21, and different amounts of charge can be captured on different droplets by changing the voltage on the charging electrode 21.

[0073] The inkjet 19 then passes between two deflection electrodes 23 and 25. A large potential difference (typically several kilovolts, often 8 to 10 kV) is applied between the deflection electrodes 23 and 25 to provide a strong electric field therebetween. Thus, the ink droplets are deflected by the electric field, and the amount of deflection depends on the amount of charge captured on each droplet. In this way, each ink droplet can be guided along a selected path.

[0074] like Figure 2 As shown, uncharged ink droplets, passing through an electric field without deflection, travel into groove 27, where they are captured. Groove 27 is formed in end piece 29 of printhead 5. End piece 29, incorporated into groove 27, is maintained at the same voltage as inkjet head 17 (normally grounded) and removes any charge from ink droplets reaching it. Suction is applied to the interior of groove 27 through groove suction line 31, and thus, ink received by groove 27 is drawn away and returned to printer body 1 via umbilical cord 7 for reuse. Droplets that miss groove 27 are deflected by the electric field between deflection electrodes 23, 25, leaving printhead 5 and forming print dots on surface 9 of object 11.

[0075] Typically, pressure vibrations are applied to the ink inside the printhead 17 using a piezoelectric device; this pressure vibration is called "pressure modulation" or simply "modulation." In the absence of pressure modulation, the inkjet 19 will naturally break into droplets due to plateau-Rayleigh instability. By applying pressure modulation at an appropriate frequency, the droplets are separated from the unsplit portion of the inkjet at the modulation frequency. The appropriate frequency depends in a known manner on the velocity of the inkjet 19 and its diameter (and therefore also on the size of the exit orifice formed by the jet of ink exiting the printhead 17). An example of modulation is described in more detail in WO 89 / 03768.

[0076] To charge each droplet to the correct level, the voltage on the charging electrode 21 should stabilize and remain at the correct level the moment the droplet separates from the unsplit portion of the inkjet 19 and during the period before the ink forming the droplet is charged. If consecutive droplets are to be charged to different charge levels, the charging signal applied to the charging electrode will need to have a step shape and will need to change the voltage at the inkjet splitting frequency, which will be the same as the modulation frequency. To properly charge each consecutive droplet, the voltage on the charging electrode 21 should be changed rapidly after each droplet separates from the unsplit portion of the inkjet 19 to allow sufficient time before the next droplet separates, allowing the voltage on the charging electrode 21 time to stabilize at the correct level. Therefore, the phase of the charging signal needs to be correct relative to the inkjet splitting phase. A process called phasing must be used to determine the inkjet splitting phase.

[0077] In an example of phase-fixing operation, a phase-fixing signal is applied to charging electrode 21. This phase-fixing signal has a square wave shape and a small voltage only for a portion (typically 50%) of each cycle of the modulation signal (the signal applied to the piezoelectric device to create pressure modulation). If a small voltage is present on charging electrode 21 when the droplet separates from the unsplit portion of the inkjet, it induces a small charge on the droplet. Otherwise, the droplet is uncharged. A detection electrode 33, called the phase electrode, is located just downstream of charging electrode 21 and detects whether each droplet is charged. The inkjet splitting phase can be determined relative to the phase of the modulation signal by stepping the phase-fixing signal through a series of possible phase positions relative to the modulation signal and by detecting which possible phase positions result in charged droplets and which result in uncharged droplets. This allows the phase of the charging signal to be adjusted as needed. For example, there may be 16 possible phase positions, each phase position spaced 22.5° phase apart from the next. The charge induced on the ink droplet by the phasing signal is small enough that the droplet still transfers to the groove 27 even after slight deflection due to the deflection field between the deflection electrodes 23 and 25. An example of phasing is described in more detail in WO 89 / 03768.

[0078] A further detection electrode 35, referred to as the time-of-flight electrode, is located between the deflection electrodes 23, 25 and the trench 27. This also detects charged droplets in a manner similar to that of the phase electrode 33. The distance between the phase electrode 33 and the time-of-flight electrode 35 is known, and by measuring the time interval between detecting a charged droplet on the phase electrode 33 and detecting a charged droplet on the time-of-flight electrode 35, it is possible to measure the velocity of the inkjet 19. In printer operation, the ink pressure is controlled so that the detected time of flight is maintained at a desired value equivalent to the required jet velocity. An example of time-of-flight measurement and ink pressure control is described in more detail in WO 89 / 03768.

[0079] exist Figure 2 and Figure 3 In this design, phase electrode 33 is shown located between charging electrode 21 and deflection electrodes 23, 25, and time-of-flight electrode 35 is shown located between deflection electrodes 23, 25 and trench 27, but other arrangements are possible. For example, phase electrode 33 and time-of-flight electrode 35 may each be mounted on the deflection electrode, as shown, for example, in WO 99 / 59822.

[0080] To ensure that the inkjet 19 splits into droplets without creating smaller "satellite" droplets between the main droplets (which is generally undesirable), the pressure modulation of the ink applied to the inkjet head 17 should have an appropriate amplitude and frequency. If the modulation amplitude is too low (undermodulation) or too high (overmodulation), and satellite droplets begin to form, the split length (the distance the inkjet 19 travels from the inkjet head 17 before splitting into droplets) is longer than it would be with the correct modulation amplitude. Since the jet velocity remains constant, the change in split length leads to a change in the split phase. Therefore, it is possible to set the modulation amplitude to an appropriate value through a process called self-modulation, in which the change in the split phase is monitored as the modulation amplitude changes. For example, the modulation amplitude can initially be set to a value that is known to be too low, and the phasing operation can be repeated while the modulation amplitude is gradually increased. First, as the modulation amplitude increases, the split phase will change in the direction corresponding to the shorter split length. At some point, as the modulation amplitude begins to increase, the split phase will begin to change in the opposite direction. This identifies a characteristic modulation amplitude close to the value at which overmodulation begins. Then, the modulation amplitude used for the printing operation is set to be slightly smaller than this characteristic value. An example of the self-modulation process is described in more detail in WO 89 / 03768.

[0081] The inkjet head 17, charging electrode 21, phase electrode 33, deflection electrodes 23 and 25, and time-of-flight electrode 35 are mounted on a substrate 37, the end of which is a terminal piece 29. A trench suction line 31 extends below the substrate 37. Electrical connections for the charging electrode 21, phase electrode 33, deflection electrodes 23 and 25, and time-of-flight electrode 35 also extend below the substrate 37, such as... Figure 3 As shown. The space above substrate 37 is enclosed by a removable printhead cover. The space below substrate 37 is enclosed by the outer casing of printhead 5. The printhead cover and the outer casing are not... Figure 2 and Figure 3 As shown in the image.

[0082] Figure 4 yes Figure 1A simplified diagram of the fluid system of an inkjet printer. Ink is stored in an ink supply cartridge 39 in the printer body 1. The ink supply cartridge 39 is the main ink cartridge of the printer. The interior of the ink supply cartridge 39 is maintained at atmospheric pressure through a vent 41. Ink is drawn from the ink supply cartridge 39 by a pump 43 via a filter 45 and an ink supply line 47. The ink pressurized by the pump 43 flows through a venturi tube 49 and returns to the ink supply cartridge 39 via an ink return line 51. A pressure transducer (pressure sensor) 53 is used to sense the ink pressure on the outlet side of the ink pump 43.

[0083] The ink supply line 15 is also connected to the outlet side of the ink pump 43 and receives pressurized ink. Therefore, the ink supply line 15 provides an ink supply path to supply pressurized ink from the ink pump 43 to the printhead 17. The ink supply valve 55 controls the ink flow along the ink supply line 15. Even when the ink supply valve 55 prevents ink from flowing along the ink supply line 15, the pump 43 can still continuously drive ink through the venturi tube 49 and back to the ink cartridge 39. The ink flow through the venturi tube 49 generates suction, and thus the venturi tube acts as a suction source. The grooved suction line 31 is connected to the suction port of the venturi tube 49 to receive suction, thereby drawing ink from the groove 27 back to the printer body 1 via the umbilical cord 7. Ink from the grooved suction line 31 is drawn into the venturi tube 49 and returned to the ink cartridge 39 via the ink return line 51. The fluid flow in the grooved suction line 31 is controlled by the grooved valve 57.

[0084] A spare solvent is stored in a solvent reservoir 59, which receives suction from a venturi tube 49 via a solvent filling line 61. If it is desired to add solvent to the ink in the ink cartridge 39 to dilute the ink and correct its viscosity, the solvent filling valve 63 in the solvent filling line 61 is briefly opened. This allows the venturi tube 49 to draw a small amount of solvent from the solvent reservoir 59 and into the ink flow passing through the venturi tube 49. The solvent drawn into the venturi tube 49 then enters the ink cartridge 39 to dilute the ink.

[0085] Spare ink is stored in ink reservoir 65, which receives suction from venturi tube 49 via ink refill line 67. When the ink level in ink cartridge 39 becomes low, ink refill valve 69 in ink refill line 67 is opened. Ink is drawn from ink reservoir 65 through venturi tube 49 and delivered to ink cartridge 39 in a manner similar to adding solvent from solvent reservoir 59.

[0086] Solvent reservoir 59 and ink reservoir 65 are supplied from solvent container 71 and ink container 73 respectively, and the operator can change containers 71 and 73 as needed. In practice, it is not always necessary to supply solvent reservoir 59 and ink reservoir 65, and the corresponding filling lines 61 and 67 can be directly connected to containers 71 and 73.

[0087] Figure 5 The diagram schematically illustrates some components inside the printer housing 1. The printer has a printer housing ink system 75, which includes... Figure 4 The components inside the printer body 1 are displayed. The printer body ink system 75 and other parts of the printer operate under the control of the control system 77. For example, the control system 77 sends control signals to the ink pump 43 and the various valves 55, 57, 63, and 69 of the printer body ink system 75. The control system 77 receives output from the pressure sensor 53 and also receives output from the level sensors in the ink cartridge 39, solvent reservoir 59, and ink reservoir 65. The control system 77 also provides output to and receives input from the touch screen display 3. Typically, the control system will include a processor (such as a microprocessor) and other electronic components well known in the art.

[0088] Fluid lines 79 connect the printer body ink system 75 to the printhead 5 via an umbilical cord 7. These fluid lines will include ink supply lines 15 and others. Figure 4 The grooved suction line 29 is shown. Electrical wiring 81 connects the control system 77 to the printhead 5 via the umbilical cord 7. These electrical lines include, for example, lines for carrying drive signals or data for controlling drive signals, lines for the piezoelectric crystal inside the inkjet head 17 (which vibrates the ink (pressure modulation)), and lines for carrying signals from the phase electrode 33 and the time-of-flight electrode 35 to the control system 77.

[0089] The printer receives power at power outlet 83, which is converted in voltage converter 85 into various voltages required internally by the printer. For example, the printer may be designed to receive 24 volts DC at power outlet 83, as power sources for generating 24 volts DC from municipal power are readily available. Voltage converter 85 uses the received 24 volts to generate the voltage required to power the electronics in control system 77, which may be, for example, 5 volts. It also supplies power to charging electrode signal source 87 and EHT power supply 89. Charging electrode signal source 87 operates under the control of control system 77 to generate a voltage (e.g., up to about 300V) to be applied to charging electrode 21 in printhead 5. EHT power supply 89 is arranged to generate a large negative voltage for deflection electrode 23 and a large positive voltage for another deflection electrode 25, typically about -4kV and +4kV, respectively. Voltage converter 85 also supplies power to the printer body ink system 75 to drive ink system components such as valves 55, 57, 63, 69 and ink pump 43.

[0090] The printer body 1 also includes a transceiver 91, which enables the control system 77 to transmit data to and receive data from outside the printer. The transceiver can transmit and receive wirelessly, for example, via a radio connection to a router for communication with the Internet or a local intranet or via communication with a cellular telephone network, and / or it can transmit via a wired connection using, for example, a USB connection or an Ethernet connection.

[0091] like Figure 5 The electrical system shown is simplified, and in practice, there will be more... Figure 5 Other components not shown in the document.

[0092] In a first embodiment, the control system 77 includes a phase instability monitoring system 93, which may be implemented at least in part by software running on one or more processors within the control system 77. During phasing operation, the control system 77 controls both the shape of the signal output from the charging electrode signal source 87 to the charging electrode 21 and the phase of that signal relative to the modulation signal of the piezoelectric device sent by the control system 77 to the inkjet head 17. The control system 77 receives signals from the phase electrode 33 and is therefore able to determine which phase position of the phasing signal output from the charging electrode signal source 87 results in a charged ink droplet, and the control system 77 identifies which possible phase position includes a split phase. The monitoring system 93 analyzes this identifier of which possible phase position includes a split phase, and in particular, analyzes changes in the identifier of which possible phase position includes a split phase to monitor phase stability or instability.

[0093] The control system 77 also receives a signal from the pressure sensor 53, which indicates the pressure of the ink on the output side of the ink pump 43. Optionally, the monitoring system 93 uses this pressure information to avoid determining split phase instability at the time when a change in split phase is a result of a change in ink pressure.

[0094] The control system 77 controls the operation of the ink pump 43 to maintain the ink pressure (sensed by the pressure sensor 53) at a target level. The control system 77 receives a signal from the time-of-flight electrode 35 and can combine this signal with a signal from the phase electrode 33 to determine the flight time of the inkjet 19 from the phase electrode to the time-of-flight electrode. If the flight time of the inkjet 19 changes from a desired value representing a desired inkjet speed, the control system 77 changes the target level of ink pressure to increase or decrease the ink pressure, and thus increase or decrease the inkjet speed, to bring the flight time back to its desired value as needed. If the target level of ink pressure required to achieve the desired flight time exceeds the desired range, it is determined that the ink viscosity is too high, and the control system 77 sends a signal to briefly open the solvent filling valve 63, allowing the venturi tube 49 to draw in a small amount of solvent. The solvent then travels to the ink supply cartridge 39 and dilutes the ink used to form the inkjet 19. Optionally, the monitoring system 93 uses information that solvent is being added to the ink (or that solvent has recently been added to the ink) to avoid determining the timing of split phase instability when the change in split phase is a result of a change in ink viscosity caused by the addition of solvent.

[0095] If the monitoring system 93 determines that the split phase is unstable, it outputs an alarm. The alarm may be a diagnosis of possible partial blockage of the printhead 17. This alarm may be stored by the control system 77 and may cause the control system 77 to perform actions at a convenient time that could potentially clear the printhead 17, such as forming a jet of solvent instead of ink, or applying suction to the interior of the printhead to draw air into it through the jet forming orifice, which may help remove any blockage in the printhead 17. Alternatively or additionally, alarms such as diagnoses of partial printhead blockage may be displayed on the touchscreen display 3 and / or sent to the transceiver 91 for transmission to devices or systems outside the printer. Alarms may be sent to mobile devices such as smartphones so that operators or other personnel can be alerted even if they are not near the printer when the alarm is output.

[0096] Preferably, the alarm includes suggestions for actions that may involve cleaning or unclogging the printhead 17. For example, a message may be displayed on the touchscreen display 3 indicating that phase instability and / or potential partial blockage of the printhead 17 have been detected, and suggesting actions such as stopping and restarting the inkjet or cleaning the outer surface of the printhead 17 that forms the inkjet 19.

[0097] If the operator instructs the printer to stop inkjet printing and restart it, the control system 77 will typically control the printer to perform a series of actions required for cleaning shutdown and cleaning jet initiation, and these actions may include: replacing inkjet 19, briefly forming a solvent jet at printhead 17; and / or drawing air into printhead 17 through the orifice used to form inkjet 19. The solvent jet dissolves blockages formed by dried ink, which may be present at the jet forming orifice of printhead 17, and drawing air through the jet forming orifice removes the blockages within printhead 17. Therefore, simply stopping and restarting inkjet printing can correct partial blockages at printhead 17.

[0098] Cleaning the outer surface of the printhead typically requires stopping inkjet printing. The operator can then remove the printhead cover from the space above the enclosing substrate 37 and clean the surface of the printhead 17 with a brush and / or solvent. After cleaning the surface of the printhead 17, the operator replaces the printhead cover and restarts inkjet printing. Therefore, this action provides the effects of stopping and restarting inkjet printing as well as cleaning the surface of the printhead 17.

[0099] The monitoring system 93 can store information about previously issued alarms. This allows it to consider the history of its previous actions. If the monitoring system 93 determines that the split phase is unstable several times in a row and outputs several consecutive alarms, it can include different information or recommendations in the different alarms. For example, it might recommend stopping and starting the inkjet printer in the first alarm, recommend cleaning the printhead 17 in the second alarm, and recommend scheduling a service engineer visit in the third alarm. This allows the monitoring system to provide a tiered response that considers previously recommended, less disruptive actions.

[0100] The monitoring system can also consider the history of operator actions. Control system 77 will be able to record when the inkjet is shut down and restarted. There may not be a way to detect whether the operator cleaned the surface of printhead 17, but typically there is a sensor to detect the removal and replacement of the printhead cover, and therefore, control system 77 can record whether this operation was performed. If monitoring system 93 determines that the split phase is unstable, it can use this information to change the content of the output alarm. For example, if no previous alarm has been issued recently (this can be defined as, for example, within the past day or past week), the monitoring system can output an alarm including a recommendation to stop and restart the jet. If a previous alarm was issued recently, and there is a record of stopping and restarting the inkjet due to the recent previous report, monitoring system 93 can output an alarm recommending cleaning printhead 17. If a previous alarm recommended cleaning printhead 17, and there is a record showing that the printhead cover was removed, indicating that the recommended cleaning was performed, monitoring system 93 can issue an alarm recommending calling a service engineer.

[0101] If desired, the monitoring system 93 may follow different procedures, and the procedures may also differ if different options are available to attempt to clear partial blockages at the inkjet head 17. The monitoring system 93 may also have rules for determining the content of alarms if there is no record indicating that action was taken in response to actions suggested in previous alarms.

[0102] Instead of outputting an alarm suggesting a call for a service engineer, the monitoring system 93 can use transceiver 91 to send a request for a service engineer to a system outside the printer, preferably to an external monitoring system or service organization, and can output an alarm including information that a service engineer has been requested.

[0103] The monitoring system may also consider its previous actions and / or the history of actions taken by the operator in other ways. For example, it may suppress further alarms or even stop analyzing data on the split phase during a set period after an alarm is issued and / or during a set period after detecting an action taken by the operator that may correct partial blockage at printhead 17. The operator may wait for a convenient moment before taking action on an alarm from monitoring system 93. Industrial marking or filling lines may typically only be shut down once a day. Therefore, if the monitoring system may not output another alarm 12 or 24 hours after it issues one, it may do so only after detecting that the operator has taken an action that could clear partial blockage during this period. The monitoring system may wait a set period, such as one hour, after detecting that the operator has taken an action before outputting another alarm. This allows time for the consequences of the operator's action to stabilize (e.g., partial blockage that has moved or split but not yet completely removed will be dissolved or washed away by the inkjet) before the monitoring system determines whether the split phase has stabilized or is still unstable.

[0104] In another embodiment, the control system 77 uses transceiver 91 to transmit data used by the monitoring system 93 of the previous embodiment to an external system. Preferably, this data is accompanied by an indication of the printer's identity, as the external system may receive data from multiple printers. The monitoring system on the external system can perform the same actions as the monitoring system 93 in the printer, except that the monitoring system on the external system cannot directly provide output to the touchscreen display or other output device in the printer. The monitoring system on the external system can provide output on the external system, and the operator on the external system can take action in response. Such actions could be sending messages to the operator and / or other personnel in the organization using the printer based on the output of the monitoring system. If suggested by the output from the monitoring system, the operator at the external system can also arrange for a service engineer to access the printer. Alternatively or additionally, the monitoring system at the external system can send alarms or other outputs to systems or devices outside the external system; for example, it can send alarms directly to the printer or mobile devices (such as the operator's or other personnel's mobile phones) without requiring action from the operator at the external system.

[0105] Figure 6 This illustrates an example of how a printer can communicate with an external system so that a monitoring system at the external system can determine whether the printer's split phase is unstable. For example... Figure 6 As shown, if enterprise 97 using printer 99 is a customer of the monitoring enterprise operating remote monitoring system 95, then transceiver 91 can be used to transmit data to remote monitoring system 95. For example... Figure 6 As shown, this transmission will typically be via the Internet 101. The printer identification information transmitted along with the data via printer 99 allows the monitoring system 95 to know which printer the data relates to. The remote monitoring system 95 can also receive data from printers of other clients 103.

[0106] like Figure 6 As shown, customer company 97 can use several printers 99. Each printer 99 can send data to the remote monitoring system 95. For example... Figure 6 As shown by the dashed line, printer 99 can be configured to send an alert to the customer's own control system 105 at the location where printer 99 is being used, instead of simultaneously sending an alert to remote monitoring system 95. Transmission from printer 99 to the customer's control system 105 can be via a dedicated cable (e.g., Ethernet) or via an intranet. This allows the customer to operate a central system to potentially monitor multiple printers 99 at multiple locations. The remote monitoring system 95 or the customer's control system 105 can send data to an application running on one or more mobile devices, such as smartphones, enabling supervisors to receive alerts in real time as they move around the customer's premises.

[0107] Service organizations typically use remote monitoring systems to provide support and service to customers. They can use data received from their customers' printers to provide information about the status of the printer group as a whole. Figure 7 An example of a display based on information about whether the split phase of each printer sending information to the remote monitoring system 95 is unstable is shown.

[0108] exist Figure 7 In the display, the upper half provides a graphical representation of the proportion of printer units with unstable split phases and potentially partially clogged inkjet heads. The graphic representation is in the form of rings, where one color represents the proportion of units without unstable split phases, while different colors represent the proportion of units with unstable split phases. Other graphical representations can be used if desired. Although in Figure 7 Not shown in the diagram, each graphical representation can be accompanied by a number indicating the proportion or total number of printers with unstable split phases. This allows operators to quickly understand the problem level across all monitored printers and the level of support or service action required. Figure 7 As shown, historical information can also be displayed. Figure 7 The report provides a percentage of the total number of printers that had unstable split phases over the past week and the past month.

[0109] like Figure 7 The lower half of the display shows the various printers 99, along with information about them. The operator can select any graphic representation from the upper half of the display, and in response, the information displayed in the lower half will be based on the corresponding time period. Figure 7 In the display, information about each printer is based on the current status of each printer, as the operator has selected "Current Fault" in the upper half of the screen. This selection is indicated by a box surrounding the "Current Fault" area in the upper half of the screen.

[0110] Figure 7 The list in the lower half provides information about each individual printer. Figure 7The system displays a "Customer" column for the name of the customer using the printer, a "Printer ID" column for the printer's unique identifier, a "Printer Type" column for the printer's type or model, and a "Fault Duration / Status" column. The "Fault Duration / Status" column (for printers currently experiencing unstable split phases) provides information about the duration of the printer's unstable split phase and the current status of the fault. For example, status information might include recommended remedial actions (e.g., operator stopping and restarting the jet, operator cleaning the printhead, or dispatching a service engineer) and whether any remedial actions have been performed. For printers that do not currently have unstable split phases, this column lists the time when the printer last experienced an unstable split phase and the actions taken to successfully resolve it. Additional or different information columns may also be provided if desired. The information columns displayed may differ when different graphical representations are selected.

[0111] By selecting the relevant column headers, you can categorize any column. Figure 7 Sort the list in the lower half. Figure 7 In the list, printers are sorted by "Duration / Status of Fault". This selection is indicated by displaying column headers in bold. When the printer list is sorted by this column, printers with a status of "Recommended Service Engineer Visit - No Engineer Visit Scheduled Yet" are placed at the top of the list. This allows operators who might be responsible for scheduling engineer visits to see their work and the current need for an engineer visit. Further down the list, operators may see printers currently experiencing unstable split phases and are advised on remedial actions that can be taken (such as stopping and restarting the inkjet or cleaning the printhead surface). This allows operators to monitor the extent to which their actions are effectively correcting the unstable split phases.

[0112] When the phase stability monitoring system determines that the split phase is unstable, it outputs an alarm in the form of a change to the entry for that printer in the "Fault Duration / Status" column to indicate the presence of a fault. If an operator is monitoring this column, this change to the printer's entry should be effective in informing the operator that the printer in question has an unstable split phase. Therefore, this may be the only form of alarm output by the monitoring system, and it can be used by the operator at the monitoring system to warn others, such as the operator of printer 99. However, it is preferable that the monitoring system also outputs its alarms in other ways, such as through messages or other changes on the display at system 93 if the operator is not actively monitoring the "Fault Duration / Status" column. As mentioned earlier, the monitoring system can also send alarm messages to the operator of printer 99 or other personnel.

[0113] If the phase stability monitoring system is installed in the customer's control system 105, it can provide... Figure 7 The display shown is similar to the one described above. However, the "Customer" column in the lower half of the display is unnecessary. If the customer's control system 105 receives data from printers at multiple locations, the "Customer" column can be replaced with a "Location" column.

[0114] Figure 8 The main hardware components of a phase stability monitoring system are shown. If the phase stability monitoring system is part of a larger system, such as… Figure 5 In the case where the monitoring system 93 is part of a larger control system 77, the phase stability monitoring system may share some or all of its hardware with other parts of the larger system. The monitoring system includes: a processor 107 that performs processing actions of the monitoring system, such as analyzing phase data; a memory 109 for storing data; a user interface 111 for receiving input from and providing output to the operator; and a communication device 113 for receiving data such as phase data and transmitting data such as alarms. The method for monitoring split phases will be implemented through a program executed by the processor 107. The program may be stored in a program memory device, which is part of the overall memory system 109 of the monitoring system.

[0115] Figure 9 This is a flowchart illustrating a general process for monitoring printer phase data and outputting an alarm when a split phase is determined to be unstable. Many examples of methods for analyzing split phases to determine instability, as given above, can be viewed as defining analysis parameters derived from the phase data and comparing these parameters with criteria for determining whether a split phase is unstable. Therefore, in step S1, Figure 9 The process reads the current phase data, and in step S2, it updates the analysis parameters to take into account the phase data read in step S1. In step S3, the analysis parameters are compared with the criteria used to define phase instability. If the parameters do not meet the criteria, the process moves to step S4. In this example, an analysis interval is set between each instance of reading phase data and updating the analysis parameters. In step S4, the process waits until the analysis interval has elapsed before returning to step S1. If the parameters meet the criteria in step S3, this corresponds to determining a split phase instability, and therefore, the process moves to step S5, where an alarm is output.

[0116] Figure 10 This is an illustration of the use of [the invention] in embodiments of the present invention. Figure 9The flowchart illustrates the modification of the general process. In this embodiment, the analysis parameter is the average magnitude of the phase change, i.e., the sum of the absolute values ​​of each change divided by the number of changes. This can be expressed by the equation Pa = ∑|Δ| / n, where Pa is the analysis parameter, |Δ| is the absolute magnitude of the phase change (e.g., the number of phase positions or phase angles that change in a single phase splitting phase), and n is the number of changes.

[0117] exist Figure 10 In the middle, steps S1 to S5 and Figure 9 The same as in, but in Figure 10 After reading the current phase data in step S1, the process moves to step S101 to check if the phase position has changed since the last phase data reading. If the phase position has not changed, there is no need to update the analysis parameter Pa, and therefore the process immediately moves to step S4 to wait for the analysis interval to pass. If the phase position has changed, the process moves to step S2, where the calculated average value used as the analysis parameter Pa is updated. In step S3, the analysis parameter (calculated average value) is compared with a criterion, in this example, the criterion being the requirement that the calculated average value exceeds a threshold, which is higher than 1 (preferably at least 1.3—corresponding to approximately 30° phase if the 360° phase period is divided into 16 possible phase positions), and preferably lower than 2. If the calculated average value does not exceed the threshold, the process moves to step S4 to wait for the analysis interval to pass. If the calculated average value does exceed the threshold, the process determines that the split phase is unstable, and it moves to step S5, where an alarm is output.

[0118] During printer operation, the split phase can be measured at intervals of one second or less. However, in Figure 10 In the analysis, the analysis interval is preferably in the range of 1 to 10 seconds, and more preferably at least 2 seconds. As mentioned above, partial clogging at the inkjet head 17 can cause a phase change of up to 360° within 10 to 15 seconds. Assuming that 360° phase corresponds to 16 possible phase positions, if the analysis interval is at least 1 second, and preferably at least 2 seconds, partial clogging at the inkjet head 17 is likely to cause a phase change at least in at least two phase positions within each analysis interval. This possibility increases if the analysis interval is at least 4 seconds. The analysis interval is preferably no more than 10 seconds, so that the interruption of the split phase lasting 10 to 15 seconds is likely to be split between at least two analysis intervals, so that the continuous values ​​of the split phase read in the analysis interval may differ due to the phase interruption. Therefore, if a suitable analysis interval is selected, partial clogging at the inkjet head 17 will almost certainly cause the calculated average value to rise above 1.

[0119] Although the process uses simple analysis, it is quite reliable in detecting phase instability caused by partial blockage at printhead 17, without mistakenly identifying minor phase changes during normal printer operation as phase instability.

[0120] As described above, when the split phase is stable, the split phase can alternate between adjacent phase positions. This results in a phase change at one phase position at a time. Other changes in the split phase that occur during normal operation with a stable split phase also tend to result in a phase change at one position at a time. Therefore, these changes in phase position do not cause the calculated average to exceed a threshold greater than one.

[0121] Therefore, the calculated average value represents a balance between small changes in the average size of a split phase, typical of stable split phases and often resulting in a phase change of one phase position or slightly more, and large changes in the average size of a split phase, typical of unstable split phases and often resulting in a phase change of two phase positions (or even more if the phase changes by three or more phase positions in a single change). Thus, the threshold should be at least 1.3 (corresponding to approximately 30° phase if the 360° phase period is divided into 16 possible phase positions), and more preferably at least 1.5 (corresponding to approximately 34° phase if the 360° phase period is divided into 16 possible phase positions). If the average size of the phase change is greater than 1.5, this means that at least half of the phase changes are changes of two phase positions, or some phase changes involve more than three positions or more. The threshold may be in the range of, for example, 1.6 (which corresponds to a 36° phase if the 360° phase period is divided into 16 possible phase positions) to 1.8 (which corresponds to approximately a 41° phase if the 360° phase period is divided into 16 possible phase positions).

[0122] The average magnitude of the phase change can be a moving average. Preferably, it is averaged over a long period or over a large number of phase changes. If the magnitude of the phase change is averaged over time, the period should be at least half an hour, preferably at least one hour, and may be longer, such as 6 hours, 12 hours, or even 24 hours. If the magnitude of the phase change is averaged over a large number of changes, the number of changes should be at least 20, and may be larger numbers, such as 100 or even 500. If the average is taken over a long period or over a large number of changes, and the split phase is stable, where almost all phase changes alter a phase position, then a large phase change in a single short period will not change the value of the average much, and therefore, Figure 10The process will not determine that the split phase is unstable in these cases. This is advantageous because a large phase change in a single, short, non-repeating period is unlikely to be caused by partial clogging at printhead 17, and regardless of the cause of the large phase change, if the large phase change in a short period is not repetitive, it is unlikely that any remedial action will be required. However, if there is partial clogging at printhead 17, the period of large phase change is likely to last longer or repeat (e.g., the period of large phase change may last 10 seconds and may repeat approximately once per minute), and therefore, the number of large phase changes will increase rapidly, causing the average size of the phase changes to greatly exceed 1. In this way, by averaging over appropriate periods or the number of changes, it is possible to... Figure 10 The process is reasonably protected from large phase changes during brief, non-repeating periods while still reliably detecting partial clogging at inkjet head 17.

[0123] As mentioned above, changes in some printer operations (such as adding solvent to dilute the ink) and other printer operating parameters (such as ink pressure) can cause changes in the split phase. Preferably, the system used to detect phase instability should not respond to these, because they are either caused by normal printer operation or are the result of problems with other operating parameters, and the phase change does not indicate an underlying problem. Figure 11 It shows how it can be modified. Figure 9 The flowchart is provided to prevent the system from determining that the split phase is unstable in these cases.

[0124] exist Figure 11 In the middle, steps S1 to S5 and Figure 9 The same as in step S4. After the analysis interval has elapsed in the process, Figure 11 The process does not immediately return to step S1. Instead, it performs one or more checks to see if there are any printer operations or changes to other printer parameters that could cause a change in the split phase that should be ignored. Figure 11 In the process, the printer checks another printer parameter (ink pressure) and a printer operation (adding solvent).

[0125] After step S4, a check is performed in step S201 to see if the ink pressure has just changed. If the pressure has just changed, the process moves to step S202, where it waits for 5 seconds. This allows any transient effects of the pressure change to complete. Then, the process moves to step S203. If the ink pressure has not just changed, the process moves directly from step S201 to step S203. In step S203, a check is performed to see if solvent has just been added to the ink. If solvent has just been added, the process moves to step S204, where it waits for 5 minutes. This allows any transient effects of the solvent addition to complete. Then, the process moves to step S1. If no solvent has just been added, the process moves directly from step S203 to step S1.

[0126] exist Figure 11 The checks performed in steps S202 and S204 are examples, and other checks may also be performed, or may replace the checks shown. The waiting periods in steps S202 and S204 depend on how long any interruption to the split phase might last, which will vary depending on the cause of the interruption. If the ink pressure changes, its effect on the split phase may be immediate, and the change in the split phase should stop immediately once the ink pressure stabilizes again. Therefore, the waiting period in step S202 is short. The waiting period in step S204 is longer to allow the added solvent time to fully mix with the ink in the ink cartridge 39, so that the ink viscosity stabilizes. The waiting periods in steps S202 and S204 are examples, and different periods may be used.

[0127] In practice, because solvent evaporation causes a gradual change in ink viscosity, ink pressure may frequently change slightly to maintain a constant flight time. These pressure changes often do not lead to a significant change in the split phase, and therefore, the process used in step S201 preferably does not result in a decision to simply change the pressure in response to such changes. This can be achieved by responding to the pressure change in step S201 only if the change is greater than a threshold amount or only if the pressure changes at a rate greater than the background change rate representing the effect of solvent evaporation. The background rate will vary depending on the printer and is largely dependent on the temperature of the printer's operating environment. However, a long-term average of the pressure changes can be used as the background rate. For example, the average rate of change between solvent filling operations can be used as the background rate.

[0128] In one implementation of step S201, the continuous ink pressure value read from pressure sensor 53 is passed through a digital high-pass filter, which is set to filter out the slow background averaging rate of pressure change, and the filter output is used to determine in step S201 whether there is a pressure change.

[0129] The analysis of phase data can be modified to remove or compensate for the effects of pressure changes in other ways, replacing the use of... Figure 11 Steps S201 and S202. For example, instead of pausing the analysis process, if there is a large or rapid pressure change, information about the pressure change can be provided as an additional input to step S2, which ignores phase changes that occur simultaneously with or immediately after the pressure change and does not use such phase changes to update the analysis parameters.

[0130] In a further alternative, the monitoring system can use pressure data (preferably high-pass filtered as described above) to predict the impact of pressure on the split phase and compensate the phase data for the predicted impact of changes in ink pressure, so that step S2 updates the analysis parameters based on the compensated phase data. For example, pressure information or its predicted impact on the split phase can be used as additional input in step S1, and the phase data supplied to step S2 can be compensated by modifying the phase data read in step S1 according to the predicted impact of the pressure information. If necessary, the predicted impact of pressure changes can be determined by testing for a specific printer model, taking into account operating settings and other factors such as temperature, and such information can be stored and made available to the monitoring system 93. Alternatively, pressure information or its predicted impact on the split phase can be used as additional input in step S2, so that step S2 can use this information during the process of updating the analysis parameters. For example, the analysis parameters can be updated based on the difference between the phase data read in step S1 and the prediction of phase data based on the pressure data, instead of using the phase data read in step S1 alone.

[0131] In practice, the split phase and ink pressure can be sensed more frequently than once per analysis interval, and therefore, better results can be obtained by compensating the phase information more frequently than once per analysis interval. Therefore, the compensation of the phase information will be performed during the waiting period in step S4, rather than as part of steps S1 or S2. For example, the pressure value can be high-pass filtered as discussed above, and the effect of the filtered pressure value on the split phase can be predicted. This predicted split phase behavior can be compared with the actual detected split phase behavior (which may also be high-pass filtered), and the phase data used in step S1 can be based on the result of this comparison; for example, the phase data can represent the difference between the predicted split phase behavior and the actual detected split phase behavior. The comparison between the predicted split phase behavior and the actual detected split phase behavior can be made with a slight time offset to account for any differences in delays in the process of obtaining the relevant data, and this is because the change in split phase caused by a pressure change will typically occur a few milliseconds after the pressure change at the pressure sensor 53 in the printer body (primarily due to the time it takes for the pressure change to propagate along the length of the umbilical 7).

[0132] The process for determining split phase instability involves analyzing phase data to identify when a stable split phase has been interrupted in some way; however, if the interruption lasts only a short time, it is not expected to determine that the split phase is unstable. Figure 12 It shows how it can be modified. Figure 9 The process is designed to provide this result. For example, if the number of different phase positions occupied within a two-minute timeframe exceeds three, a split phase can be considered an interruption; however, a split phase is only considered unstable if this situation persists for more than ten minutes. Figure 12 In the middle, steps S1 to S5 and Figure 9 The same applies in step S2. In this example, the parameter will be the number of different phase positions occupied in the past two minutes, and in step S3, the criterion will be that the number of different phase positions should exceed three. However, in Figure 12 In this process, the process does not move directly to step S4 or step S5 after step S3.

[0133] If in Figure 12If the parameters in step S3 meet the criterion, the split phase is interrupted. Therefore, the process needs to check if the interruption lasts long enough (ten minutes in the example given above) to determine if the split phase is unstable. The process uses a timer to determine if the interruption lasts long enough. Therefore, the process moves to step S301, where it checks if the timer is already running. If the timer is not running, the process moves to step S302 to start the timer, and then moves to step S4 to wait for the analysis interval to pass. If the timer is already running in step S301, the process moves to step S303 to check if the timer has reached its target value (ten minutes in the example given above). If the timer has reached its target value, it is determined that the split phase has been interrupted long enough to be considered unstable, and the process moves to step S5 to output an alarm. If the timer has not reached its target value in step S303, the process moves directly to step S4 to wait for the analysis interval to pass.

[0134] If in Figure 12 If the parameters in step S3 do not meet the criterion, the split phase is not interrupted. The process moves to step S304, where it checks whether the timer is running. If the timer is running, the process moves to step S305 to stop and reset the timer, because the split phase is not currently interrupted, and therefore, the phase interruption period has not lasted long enough to consider the split phase unstable. The process then moves to step S4 to wait for the analysis interval to pass. If the timer is not running in step S304, the process moves directly to step S4.

[0135] If desired, it can also be done in Figure 12 Refer to the process Figure 11 The inspections discussed, such as those in Figure 12 The process includes steps S201 to S204, indicated by dashed lines. However, if step S203 is performed and solvent has just been added to the ink, causing the process to wait for 5 minutes in step S204, this waiting period is long enough that it is impossible to determine whether the split phase was interrupted during this time. Therefore, in this case, the timer is stopped and reset in step S205, and the timing of any interrupted period must be restarted after the waiting period in step S204 is completed. Other methods, such as the alternative method using ink pressure data discussed above, can also be used for checking.

[0136] The process for determining split phase instability analyzes phase data to identify interruption events that disrupt the split phase in some way. However, it is desirable that split phase instability be determined only if there are at least a set number of interruption events within a set time period, rather than in response to a single isolated interruption event. Figure 13 It shows how it can be modified. Figure 9 The process is to provide that result.

[0137] exist Figure 13 In the middle, steps S1 to S5 and Figure 9 The same applies to the previous steps. In step S2, the parameters used to define the interrupt event are updated, and in step S3, the parameters are checked against the criteria for determining whether an interrupt event has occurred. Figure 13 In step S3, the process does not directly proceed to step S4 or S5. Instead, if an interruption event is determined to have occurred in step S3, the process proceeds to step S401. A counter is used to count the number of interruption events, and a timer is used to measure the set time period during which the number of interruption events is counted. In step S401, the counter is incremented because an interruption event was detected in step S3. Then, in step S402, the process checks if the timer is running. If the timer is not running, it is started in step S403. Then, the process proceeds to step S404. If the timer is already running in step S402, the process proceeds directly to step S404. In step S404, the process checks if the counter has reached its target (i.e., the set number of interruption events). If the counter has reached its target, the process proceeds to step S5 to output an alarm, and then the process proceeds to step S4 to wait for the analysis period to pass.

[0138] If the counter has not reached its target in step S404, the process moves to step S405, where it checks whether the timer has reached its target (i.e., the set time period for counting the number of interrupt events has expired). If the timer has reached its target, it means that the set time period has expired, during which fewer than the set number of interrupt events were counted. Therefore, it cannot be determined that the split phase is unstable. In this case, the timer is stopped and reset in step S406, and the counter is reset in step S407. The process then moves to step S4 to wait for the analysis period to pass. If the timer has not reached its target in step S405, the process moves directly to step S4.

[0139] If the parameters do not meet the criteria in step S3, it means that no interruption event was detected. In this case, the process moves to step S408, where it checks if the timer is running. If the timer is running, the process moves to step S405 to check if the timer has reached its target. If the timer is not running, the process moves to step S4 to wait for the analysis period to pass.

[0140] Although Figure 13 It is not shown in the text, but it can also be used with if desired. Figure 12 Refer to the same process as in the article. Figure 11 The checks discussed. However, if performed... Figure 12 Step S205 should be modified to reset the counter and stop and reset the timer. Alternatively, other methods discussed above can be used for checking, such as the alternative method of using ink pressure data discussed above.

[0141] Partial clogging at printhead 17 can cause a phase change of approximately 360° within ten to fifteen seconds, and this behavior may repeat at intervals of thirty seconds to one minute. Even slight partial clogging at printhead 17 can cause repeated phase changes, and if this phase change reaches three possible phase positions (assuming the 360° phase is divided into 16 possible phase positions), which corresponds to a 67.5° phase, it can affect print quality. Therefore, detecting phase instability caused by slight partial clogging can be useful to avoid such impact on print quality. Thus, if the phase position ranges to 67.5° or greater within a 30-second time period (three or more possible phase positions if the entire phase period is divided into 16 possible phase positions), embodiments of the invention determine that a phase break has occurred, and if the phase break occurs in at least five 30-second time periods within a 30-minute period, phase instability is determined. In this embodiment, the process for monitoring the printer's phase data and outputting an alarm when phase instability is determined can use... Figure 13 The process is as follows. In this case, the target of the counter in steps S401 and S404 is 5, and the target of the timer in steps S403 and S405 is 30 minutes. In step S2, the analysis parameter is the range of phase positions within a 30-second time period, and the criterion in step S3 is that the range is 67.5° or greater phase. Figure 14 This is a flowchart illustrating the process within step S2 of this embodiment. The length of time and the number of interruption periods in this embodiment are examples, and other values ​​can be selected.

[0142] exist Figure 14In this process, a 30-second timer is used to define a 30-second analysis period. If the analysis interval in step S4 is 5 seconds, the 30-second timer can be implemented by counting the number of times the process of step S2 has been executed, since six 5-second analysis intervals will take 30 seconds. After reading the current phase data in step S1, the process of step S2 begins by determining in step S501 whether the phase position has changed since the last execution of step S2. If the phase position has changed, the new phase position is added to the list of phase positions in step S502. Then, the process moves to step S503 to check the 30-second timer. If the phase position has not changed in step S501, the process moves directly to step S503.

[0143] In step S503, the process checks if the 30-second timer has ended. If it hasn't, the process proceeds directly to step S4 to wait for the analysis interval to pass and reads the next phase data in step S1. In this embodiment, only step S2 is completed, and the process moves to step S3 every 30 seconds. If the 30-second timer has ended as step S503, the process in step S2 moves to step S504, where the range of phase positions in the list is determined and set as the analysis parameter provided to step S3. Then, in step S505, the list is cleared, and the 30-second timer is restarted to begin another 30-second analysis period. This completes step S2, and the process moves to... Figure 13 Step S3 in the process.

[0144] In most operating situations of the printer, Figure 13 and Figure 14 The analysis process should reliably respond to interruptions caused by partial blockage at inkjet head 17 to determine split phase instability, but not to most phase changes not caused by partial blockage at inkjet head 17.

[0145] As an alternative, the criterion in step S3 could be a phase range of 45° or greater, rather than 67.5° or greater (assuming a 360° phase is divided into 16 possible phase positions, this corresponds to two or more possible phase positions, rather than three or more), in order to detect minor clogging before it affects print quality. However, this could increase the risk of incorrectly identifying partial clogging at printhead 17 that could cause phase instability, which is not the case.

[0146] If the goal is simply to detect more severe partial blockages to minimize the chance of determining split phase instability, for example, when there is no actual partial blockage at printhead 17, the criterion in step S3 could require a larger minimum phase position range (e.g., 90° or even higher) instead of 67.5°, which carries the risk that some degree of print quality degradation due to less severe blockages may become more prevalent.

[0147] The embodiments discussed above are given by way of example and should not be considered as limiting the scope of the claims.

Claims

1. A monitoring system, configured as follows: Receive printer data from an electrostatically deflected continuous inkjet printer and obtain phase data from the printer data, the phase data being data indicating: (a) which of a set of possible phase positions comprises the split phase of the inkjet from the printer at each analysis time in a series of analysis times; and / or (b) the change of the split phase of the inkjet from one of the possible phase positions to another; and The phase data is analyzed to determine if there is a partial blockage at the jet forming device of the printer, and if a partial blockage is determined, an alarm is output. The monitoring system is configured not to output an alarm in response to the alternation of the split phase between adjacent phase positions.

2. The monitoring system according to claim 1, wherein the monitoring system is configured to output an alarm if the number of interrupted phase events exceeds a predetermined threshold within a first predetermined time length. The predetermined thresholds are at least two, the first predetermined time length is at least one minute, and if the range of change of the split phase within the second predetermined time length is equal to or greater than a preset phase difference, then a phase interruption event occurs. The second predetermined time length is no greater than half of the first predetermined time length, and the preset phase difference is at least 45° or covers a plurality of possible phase positions covering at least 45° of phase.

3. The monitoring system of claim 1, wherein, The alert includes a diagnosis of a possible partial blockage at the jet forming device of the printer and / or recommendations for actions to be taken.

4. The monitoring system according to claim 1, wherein it is located outside the printer.

5. A monitoring system, configured as follows: Receive printer data from an electrostatically deflected continuous inkjet printer and obtain phase data from the printer data, the phase data being data indicating: (a) which of a set of possible phase positions comprises the split phase of the inkjet from the printer at each analysis time in a series of analysis times; and / or (b) the change of the split phase of the inkjet from one of the possible phase positions to another; and The phase data is analyzed using at least one of the following: (a) the number of possible phase positions or the magnitude of the change in the split phase from one analysis time to the next, expressed in phase angles; (b) the range of the split phase change within a set time period; or (c) whether the continuous changes in phase are in the same direction as each other, to determine whether the split phase is unstable, and if the split phase is determined to be unstable, an alarm is output.

6. The monitoring system of claim 5, wherein the monitoring system is arranged not to output an alarm in response to the alternation of the split phase between adjacent phase positions.

7. The monitoring system according to any one of the preceding claims, wherein the monitoring system is arranged to obtain other data from the printer data, the other data being data relating to operations other than the formation of inkjet at the jet forming apparatus of the printer, and / or data relating to a detected state or a change in a detected state other than the split phase in the printer; and the monitoring system is arranged to not output the alarm if a predetermined condition is indicated by the other data, or to compensate the phase data or analyze the phase data in a manner that compensates for the predicted impact of the predetermined condition on the split phase.

8. The monitoring system according to any one of claims 5-6, wherein the monitoring system is arranged to output an alarm if the number of interrupted phase events exceeds a predetermined threshold within a first predetermined time length. The predetermined thresholds are at least two, the first predetermined time length is at least one minute, and if the range of change of the split phase within the second predetermined time length is equal to or greater than a preset phase difference, then a phase interruption event occurs. The second predetermined time length is no greater than half of the first predetermined time length, and the preset phase difference is at least 45° or covers a plurality of possible phase positions covering at least 45° of phase.

9. The monitoring system of claim 7, wherein, The other data includes data related to the pressure of the pressurized ink in the printer, and the predetermined conditions include at least some of the conditions in which the pressure of the pressurized ink changes.

10. The monitoring system of claim 7, wherein, The predetermined situation includes performing an operation to dilute the ink in the printer.

11. The monitoring system according to claim 5, wherein, The alert includes a diagnosis of a possible partial blockage at the jet forming device of the printer and / or recommendations for actions to be taken.

12. The monitoring system according to claim 5, wherein it is located outside the printer.

13. A monitoring system, configured as follows: Receive printer data from an electrostatic deflection continuous inkjet printer, and obtain phase data and other data from the printer data. The phase data is data that indicates the following information: (a) which of a set of possible phase positions comprises the split phase of the printer's inkjet at each analysis time in a series of analysis times; and / or (b) the change of the split phase of the inkjet from one of the possible phase positions to another; and The other data is data relating to operations other than inkjet formation at the jet forming apparatus of the printer, and / or data relating to detected states or changes in detected states other than the split phase in the printer; as well as The phase data is analyzed to determine whether the split phase is unstable, and if the split phase is determined to be unstable, an alarm is output. The monitoring system is configured to not output the alarm in the event of a predetermined condition indicated by the other data, or to compensate for or analyze the phase data in relation to the predicted impact of the predetermined condition on the split phase.

14. The monitoring system of claim 13, wherein the monitoring system is arranged not to output an alarm in response to the alternation of the split phase between adjacent phase positions.

15. The monitoring system according to any of the preceding claims, wherein the monitoring system is arranged not to output an alarm in response to a total phase change comprising no more than 45° of phase and a phase change period lasting no longer than 15 seconds and not repeating within one hour.

16. The monitoring system according to any one of claims 13-14, wherein the monitoring system is arranged to output an alarm if the average magnitude of the change in the split phase from one analysis time to the next analysis time, expressed in terms of the number of possible phase positions or in terms of phase angle, exceeds a predetermined threshold.

17. The monitoring system according to any one of claims 13-14, wherein the monitoring system is arranged to output an alarm if the number of interrupted phase events exceeds a predetermined threshold within a first predetermined time length. The predetermined thresholds are at least two, the first predetermined time length is at least one minute, and if the range of change of the split phase within the second predetermined time length is equal to or greater than a preset phase difference, then a phase interruption event occurs. The second predetermined time length is no greater than half of the first predetermined time length, and the preset phase difference is at least 45° or covers a plurality of possible phase positions covering at least 45° of phase.

18. The monitoring system of claim 13, wherein, The other data includes data related to the pressure of the pressurized ink in the printer, and the predetermined conditions include at least some of the conditions in which the pressure of the pressurized ink changes.

19. The monitoring system of claim 13, wherein, The predetermined situation includes performing an operation to dilute the ink in the printer.

20. The monitoring system of claim 16, wherein, The threshold is at least 1.3 possible phase positions or at least 30° of phase.

21. The monitoring system of claim 17, wherein, The preset phase difference is at least 67.5° or multiple possible phase positions covering at least 67.5° of phase.

22. The monitoring system of claim 17, wherein, The preset phase difference is at least 90° or multiple possible phase positions covering at least 90° of phase.

23. The monitoring system of claim 17, wherein, The preset phase difference is at least 135° or multiple possible phase positions covering at least 135° of phase.

24. The monitoring system of any one of claims 21-23, wherein, The predetermined threshold is at least three, and the second predetermined time length is no greater than one-third of the first predetermined time length.

25. The monitoring system of claim 24, wherein, The predetermined threshold is at least five, and the second predetermined time length is no greater than one-fifth of the first predetermined time length.

26. The monitoring system of any one of claims 21-23, wherein, The second predetermined time length is at least 5 seconds and no more than 5 minutes.

27. The monitoring system of any one of claims 21-23, wherein, The alert includes a diagnosis of a possible partial blockage at the jet forming device of the printer and / or recommendations for actions to be taken.

28. The monitoring system according to any one of claims 21-23, wherein it is located outside the printer.

29. A monitoring method, comprising: Receive printer data from an electrostatic deflection continuous inkjet printer and obtain phase data from the printer data, the phase data being data indicating the following information: (a) indicating which of a set of possible phase positions includes the split phase of the inkjet from the printer at each analysis time in a series of analysis times; and / or (b) indicating the change of the split phase of the inkjet from one of the possible phase positions to another. as well as The phase data is analyzed to determine if there is a partial blockage at the jet forming device of the printer, and an alarm is output in response to the determination that there is a partial blockage at the jet forming device of the printer. Furthermore, it will not output an alarm in response to the alternation of the split phase between adjacent phase positions.

30. The monitoring method of claim 29, wherein, It will not issue an alarm in response to a total phase change of no more than 45° or a phase change period that lasts no longer than 15 seconds and does not repeat within an hour.

31. The monitoring method of any one of claims 29-30, comprising: An alarm is output if the number of possible phase positions or the average magnitude of the phase change from one analysis time to the next, expressed as phase angle, exceeds a predetermined threshold.

32. The monitoring method of any one of claims 29-30, comprising: If the number of interrupt phase events within a first predetermined time period exceeds a predetermined threshold, an alarm will be output. The predetermined thresholds are at least two, the first predetermined time length is at least one minute, and if the range of change of the split phase within the second predetermined time length is equal to or greater than a preset phase difference, then a phase interruption event occurs. The second predetermined time length is no greater than half of the first predetermined time length, and the preset phase difference is at least 45° or covers a plurality of possible phase positions covering at least 45° of phase.

33. The monitoring method of any one of claims 29-30, wherein, The alert includes a diagnosis of a possible partial blockage at the jet forming device of the printer and / or recommendations for actions to be taken.

34. The monitoring method according to any one of claims 29-30, wherein it is performed outside the printer.

35. The monitoring method according to any one of claims 29-30, wherein it is performed inside the printer.

36. A monitoring method, comprising: Receive printer data from an electrostatic deflection continuous inkjet printer and obtain phase data from the printer data, the phase data being data indicating the following information: (a) indicating which of a set of possible phase positions includes the split phase of the inkjet from the printer at each analysis time in a series of analysis times; and / or (b) indicating the change of the split phase of the inkjet from one of the possible phase positions to another. as well as The phase data is analyzed using at least one of the following: (a) the number of possible phase positions or the magnitude of the change in the split phase from one analysis time to the next, expressed in phase angles; (b) the range of change of the split phase within a set time period; or (c) whether the continuous changes in phase are in the same direction as each other, to determine whether the split phase is unstable, and in response to determining that the split phase is unstable, an alarm is output.

37. The monitoring method of claim 36, wherein, An alarm will not be output in response to the alternation of the split phase between adjacent phase positions.

38. The monitoring method according to any one of claims 36-37, comprising obtaining other data from the printer data, said other data being data relating to operations other than the inkjet forming apparatus of the printer, and / or data relating to a detected state or a change in a detected state other than the split phase in the printer; And wherein, In the event of a predetermined condition indicated by the other data, the alarm is not output, or the phase data is compensated for or analyzed in a manner that compensates for the predicted impact of the predetermined condition on the split phase.

39. The monitoring method of any one of claims 36-37, wherein, It will not issue an alarm in response to a total phase change of no more than 45° or a phase change period that lasts no longer than 15 seconds and does not repeat within an hour.

40. The monitoring method of any one of claims 36-37, comprising: An alarm is output if the number of possible phase positions or the average magnitude of the phase change from one analysis time to the next, expressed as phase angle, exceeds a predetermined threshold.

41. The monitoring method according to any one of claims 36-37, comprising: If the number of interrupt phase events within a first predetermined time period exceeds a predetermined threshold, an alarm will be output. The predetermined thresholds are at least two, the first predetermined time length is at least one minute, and if the range of change of the split phase within the second predetermined time length is equal to or greater than a preset phase difference, then a phase interruption event occurs. The second predetermined time length is no greater than half of the first predetermined time length, and the preset phase difference is at least 45° or covers a plurality of possible phase positions covering at least 45° of phase.

42. The monitoring method of claim 38, wherein, The other data includes data related to the pressure of the pressurized ink in the printer, and the predetermined conditions include at least some of the conditions in which the pressure of the pressurized ink changes.

43. The monitoring method of claim 38, wherein, The predetermined situation includes performing an operation to dilute the ink in the printer.

44. The monitoring method of claim 36, wherein, The alert includes a diagnosis of a possible partial blockage at the jet forming device of the printer and / or recommendations for actions to be taken.

45. The monitoring method according to any one of claims 36-37, wherein it is performed outside the printer.

46. ​​The monitoring method according to any one of claims 36-37, wherein it is performed inside the printer.

47. A monitoring method, comprising: Receive printer data from an electrostatic deflection continuous inkjet printer, and obtain phase data and other data from the printer data. The phase data is data that indicates the following information: (a) which of a set of possible phase positions comprises the split phase of the printer's inkjet at each analysis time in a series of analysis times; and / or (b) the change of the split phase of the inkjet from one of the possible phase positions to another; and The other data is data relating to operations other than inkjet formation at the jet forming apparatus of the printer, and / or data relating to detected states or changes in detected states other than the split phase in the printer; as well as The phase data is analyzed to determine whether the split phase is unstable, and if the split phase is determined to be unstable, an alarm is output. Furthermore, in cases where a predetermined condition is indicated by the other data, the alarm is not output, or the phase data is compensated for or analyzed in accordance with the predicted impact of the predetermined condition on the split phase.

48. The monitoring method of claim 47, wherein, An alarm will not be output in response to the alternation of the split phase between adjacent phase positions.

49. The monitoring method according to any one of claims 47-48, wherein, It will not issue an alarm in response to a total phase change of no more than 45° or a phase change period that lasts no longer than 15 seconds and does not repeat within an hour.

50. The monitoring method of any one of claims 47-48, comprising: An alarm is output if the number of possible phase positions or the average magnitude of the phase change from one analysis time to the next, expressed as phase angle, exceeds a predetermined threshold.

51. The monitoring method of any one of claims 47-48, comprising: If the number of interrupt phase events within a first predetermined time period exceeds a predetermined threshold, an alarm will be output. The predetermined thresholds are at least two, the first predetermined time length is at least one minute, and if the range of change of the split phase within the second predetermined time length is equal to or greater than a preset phase difference, then a phase interruption event occurs. The second predetermined time length is no greater than half of the first predetermined time length, and the preset phase difference is at least 45° or covers a plurality of possible phase positions covering at least 45° of phase.

52. The monitoring method according to claim 47, wherein, The other data includes data related to the pressure of the pressurized ink in the printer, and the predetermined conditions include at least some conditions where there is a change in the pressure of the pressurized ink.

53. The monitoring method according to claim 52, wherein, The predetermined conditions include changes in ink pressure exceeding a preset amount and / or changes in ink pressure at a rate exceeding a preset amount.

54. The monitoring method of any one of claims 52-53, wherein, For phase data indicating the position or change of the split phase during and / or for a preset period immediately following the change of ink pressure, the phase data is not analyzed, or the alarm is not output in response to the analysis of the phase data.

55. The monitoring method of any one of claims 52-53, wherein, For phase data indicating the position or change of the split phase during and / or for a predetermined period immediately following the change of ink pressure, (a) the phase data is compensated for the predicted effect of the change of ink pressure on the split phase, and the analysis of the phase data includes analyzing the compensated phase data, or (b) the analysis of the phase data includes analyzing the difference between the phase data and the prediction of the phase data based on the change of ink pressure.

56. The monitoring method of any one of claims 52-53, wherein, The predetermined situation includes performing the operation of diluting the ink in the printer.

57. The monitoring method of claim 50, wherein, The threshold is at least 1.3 possible phase positions or at least 30° of phase.

58. The monitoring method of claim 57, wherein, The threshold is in the range of 1.5 to 1.8 possible phase positions or in the phase range of 34° to 41°.

59. The monitoring method of claim 51, wherein, The preset phase difference is at least 67.5° or multiple possible phase positions covering at least 67.5° of phase.

60. The monitoring method according to claim 51, wherein, The preset phase difference is at least 90° or multiple possible phase positions covering at least 90° of phase.

61. The monitoring method of claim 51, wherein, The preset phase difference is at least 135° or multiple possible phase positions covering at least 135° of phase.

62. The monitoring method of any one of claims 59-61, wherein, The predetermined threshold is at least three, and the second predetermined time length is no greater than one-third of the first predetermined time length.

63. The monitoring method of claim 62, wherein, The predetermined threshold is at least five, and the second predetermined time length is no greater than one-fifth of the first predetermined time length.

64. The monitoring method of any one of claims 59-61, wherein, The second predetermined time length is at least 5 seconds and no more than 5 minutes.

65. The monitoring method according to any one of claims 59-61, wherein, The alert includes a diagnosis of a possible partial blockage at the jet forming device of the printer and / or recommendations for actions to be taken.

66. The monitoring method of claim 65, wherein, The alert includes a proposal of action to be taken, and the content of the proposal depends at least in part on the content of one or more previous alerts.

67. The monitoring method according to any one of claims 59-61, wherein it is performed outside the printer.

68. The monitoring method according to any one of claims 59-61, wherein it is performed inside the printer.

69. An electrostatic deflection continuous inkjet printer, comprising a monitoring system according to any one of claims 1 to 28.

70. A program memory device having a program stored thereon for performing the monitoring method according to any one of claims 29-68.

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