JP2014069311A - Inkjet recording device and service life determination method for recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately predict and determine a service life of a recording head by obtaining variation of driving conditions of the recording head, in an inkjet recording device.SOLUTION: A difference between a re-measured optimum driving condition and an initial optimum driving condition of the recording head that is used is calculated (S406). Next, it is determined whether or not the difference is equal to or greater than a predetermined threshold value (S407). When the difference is equal to or greater than the threshold value, it is determined that a durable life of the recording head has reached an end, replacement of the recording head is prompted and this processing is ended. A variation amount of the optimum driving condition is obtained in advance when the service life of the recording head ends, and the varying amount is set to the predetermined threshold value. By a determination based on the threshold value, the service life of the recording head is determined and predicted. Thus, the service life of the recording head is accurately predicted and determined.

Description

  The present invention relates to an inkjet recording apparatus and a recording head lifetime determination method, and more particularly to a technique for predicting the lifetime of a recording head that ejects ink.

  Conventionally, as a technique for predicting the life of an ink jet recording head, Patent Document 1 describes that the number of ejections in a recording head is counted and the life of the recording head is predicted and determined based on the accumulated count value. . Specifically, when the cumulative count value of a certain nozzle exceeds the specified number of times, it is determined that the life of the recording head is reached, and the user is prompted to replace the head.

JP 2007-168296 A

  However, the technique described in Patent Document 1 may not have sufficient accuracy for predicting the life of the recording head.

  In a recording head in which bubbles are generated in the ink by the heat generated by the electrothermal conversion element and the ink is discharged by a change in pressure of the bubbles, the above-described thermal energy required for ink discharge is the electric heat that generates the heat. This is related to the thickness of the protective film of the conversion element. That is, by forming a protective film between the electrothermal conversion element and the ink, it is possible to eliminate the influence of the ink on the electrothermal conversion element and prevent disconnection of the element. And, as the thickness of the protective film increases, it becomes difficult for energy to be transmitted from the electrothermal conversion element to the ink. Therefore, it is necessary to increase the energy for discharging according to the thickness.

  On the other hand, the thickness of the protective film changes according to the number of ejections. In other words, the impact associated with the generation and disappearance of bubbles generated by heat may be repeated upon ejection to act on the protective film, and the protective film may be scraped off to reduce its thickness. FIG. 1 is a diagram showing the relationship between the thickness of the protective film and the number of ejections, where the horizontal axis represents the cumulative number of ejections and the vertical axis represents the protective film thickness. Here, the number of times of ejection is the number of times that one electrothermal conversion element is driven for ejection. In FIG. 1, the curves indicated by 1- (a), 1- (b), and 1- (c) are cumulative when the energy at the time of ejection, that is, the driving energy applied to the electrothermal transducer is increased in this order. The relationship between the number of ejections and the protective film thickness is shown. As can be seen from this figure, the greater the drive energy, the greater the reduction in the thickness of the protective film with respect to the increase in the number of ejections. In addition, regardless of the amount of drive energy, the change in the thickness of the protective film does not change linearly according to the number of ejections, but decreases rapidly as the number of ejections increases.

  Thus, the thickness of the protective film cannot be accurately predicted simply by the number of ejections, and depends on driving conditions such as the magnitude of driving energy for the electrothermal transducer. As in the past, when the life of a recording head is predicted based on the number of ejections, an inaccurate prediction may result in a defective recording due to ejection failure of the recording head, or even though it can still be used sufficiently. Inconveniences such as replacement of the recording head occur. In other words, the inventors of the present application have made the present invention by paying attention to the fact that the optimum driving conditions of the electrothermal transducer at that time differ depending on the thickness of the protective film that changes. .

  That is, an object of the present invention is to provide an ink jet recording apparatus and a recording head life determination method capable of predicting and determining an accurate life of a recording head by obtaining a change in optimum driving conditions.

  Therefore, the present invention is an ink jet recording apparatus that performs recording using a recording head that discharges ink by applying electric pulses to the electrothermal conversion element, and applies the ink to the electrothermal conversion element that can discharge ink. First driving condition acquisition means for acquiring the initial optimum driving condition of the recording head as the first condition, and the optimum driving condition after using the recording head. A second drive condition acquisition unit that acquires two conditions, a difference value acquisition unit that obtains a difference between the optimal drive condition of the first condition and the optimal drive condition of the second condition, and whether the difference is equal to or greater than a predetermined threshold value And determining means for determining that the recording head is at the end of its life when the difference is equal to or greater than the threshold value.

  According to the above configuration, it is possible to obtain a change in the optimum driving condition and to predict and judge an accurate life of the recording head based on the change.

FIG. 6 is a diagram illustrating a relationship between the thickness of a protective film of a discharge heater in the recording head and the number of discharges. 1A and 1B are a perspective view and a cross-sectional view, respectively, schematically showing an ink jet printer as an ink jet recording apparatus according to an embodiment of the present invention. FIG. 3 is a block diagram illustrating a configuration of a printing system including the printer 1 illustrated in FIG. 2 and a computer that is a host device thereof. 4 is a flowchart illustrating processing for obtaining an optimum driving condition of an electrothermal conversion element (discharge heater) in a recording head and determining the life of the recording head based on the condition according to the first embodiment of the present invention. It is a flowchart which shows the detail of the optimal drive condition determination process of step S401 shown in FIG. It is a figure which shows the test conditions of this embodiment in the optimal drive condition determination process. It is a figure explaining the test | inspection pattern which concerns on this embodiment. (A), (b) and (c) is a figure which shows typically the read image of the test | inspection pattern which concerns on this embodiment. It is a figure which shows the relationship of the number of normal discharge nozzles with respect to inspection conditions based on the reading result of the said inspection pattern. (A) And (b) is a figure explaining the relationship between the optimal drive condition which concerns on this embodiment, and the protective film thickness which changes. 10 is a flowchart showing a process for determining an optimum driving condition of an electrothermal transducer (discharge heater) in a recording head and determining the life of the recording head based on the condition according to a second embodiment of the present invention. It is a figure which shows the change of the voltage pulse application time of the optimal drive condition with respect to the frequency | count of discharge based on the 2nd Embodiment of this invention. FIG. 6 is a diagram illustrating a relationship between a difference value from an initial optimum driving condition of a recording head and the number of ejections until the next remeasurement timing.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, elements having the same function are denoted by the same reference numerals, and repeated description thereof is omitted.

(First embodiment)
2A and 2B are a perspective view and a cross-sectional view, respectively, schematically showing an inkjet printer 1 as an inkjet recording apparatus according to an embodiment of the present invention. When normal recording is performed with this ink jet printer, the recording medium 3 fed from the paper feeding unit 4 is transported by the rotation of a plurality of transport rollers 5 arranged above and below. This recording medium 3 is conveyed from the left side to the right side as indicated by the arrows in the figure. Next, after recording by the recording head 2, the paper is discharged onto the paper discharge tray 7. The recording medium 3 is specifically in the form of a roll paper, and only a part of the recording medium 3 is shown in the figure.

  In the ink jet printer according to the present embodiment, a driving condition determination process for the recording head 2 is performed as will be described in detail later. The reading unit 6 reads the inspection pattern recorded in the process. In this embodiment, the reading unit 6 is a CCD line sensor, and the reading resolution is 1200 dpi.

  As shown in the cross-sectional view of the ink jet printer 1 along the conveyance direction (sub-scanning direction) of the recording medium in FIG. 2B, the image read by the reading unit 6 is an image processing apparatus described later with reference to FIG. It is analyzed by processing executed by the CPU constituting the control unit. The recording head 2 of the present embodiment is a recording head 2C, 2M, 2Y, or 2K that ejects four colors of ink of C (cyan), M (magenta), Y (yellow), and K (black), respectively. These recording heads are of a so-called full line type in which nozzles are arranged over the width of the recording medium to be conveyed, and the recording medium 3 is conveyed relative to these recording heads to perform a recording operation. In this embodiment, a printer using four colors of C, M, Y, and K will be described as an example. However, the application of the present invention is not limited to a recording head of these ink colors. Any other type of ink such as light cyan, light magenta, light gray, red, and green may be used.

  FIG. 3 is a block diagram showing a configuration of a printing system mainly composed of the printer 1 shown in FIG. 2 and a computer which is a host device thereof. The host computer 300 includes a video card 204 to which a CPU 301, a ROM 302, a RAM 303, and a monitor 313 (which may include a touch panel) are connected. Furthermore, a storage device 305 such as a hard disk drive or a memory card is provided as a storage area. In addition, a pointing device 306 such as a mouse, a stylus, and a tablet, and an interface 308 for a serial bus such as a USB and IEEE1394 for connecting a keyboard 307 and the like are provided. Furthermore, a network interface card (NIC) 315 connected to the network 314 is provided. These components are connected to each other via a system bus 309. Further, the printer 1, the CCD camera 311, the scanner 312 and the like described above with reference to FIG. Furthermore, image data can also be input from a device that optically acquires image data such as a digital camera or digital video, or a portable medium such as a magnetic disk, an optical disk, or a memory card. The input image data can be in a form included in an image file.

  The CPU 301 loads a program stored in the ROM 302 or the storage device 305 (including a processing program described later in FIG. 4 and the like) into the RAM 303 as a work memory, and executes the program. The CPU 301 realizes the function of the program by controlling each of the above components via the system bus 309 according to the program. Further, in the storage devices such as the memories of the ROM 302 and RAM 303 and the storage device 305, information related to the optimum driving conditions of the recording head, which will be described later, can be stored. This information may be any information as long as it is information indicating a driving condition.

  In the present embodiment, processing related to the print head life determination, which will be described later with reference to FIG. 4 and the like, is performed in the host apparatus 300, but the application of the present invention is not limited to this form. For example, the printer 310 may perform all or part of the processing related to life determination described below. In a form in which a part is performed, other processing can be performed in the host device 300, for example.

  FIG. 4 is a flowchart showing a process for determining the optimum driving condition of the electrothermal conversion element (discharge heater) in the print head and determining the life of the print head based on the optimum drive condition according to the embodiment of the present invention.

  This process is performed when a new recording head is mounted. In step S401, an inspection pattern is recorded as a process when the new recording head is mounted, and the optimum of the new recording head is determined based on the read result of this pattern. A drive condition (first condition) is acquired (first drive condition acquisition). In step S402, the calculated initial optimum driving condition information is stored in a predetermined memory. Note that this process may be performed at the time of starting the normal recording process. That is, when the recording process is started, whether or not the mounted recording head is newly mounted is determined by, for example, reading predetermined information stored in a memory provided in the recording head. . In the case of a newly mounted recording head, first, processing in steps S401 and S402 described below is performed. If it is not a newly mounted recording head, the processes in steps S401 and S402 are skipped, and the processes in and after step S403 described below are performed.

  First, the outline of the optimum drive condition obtained in step S401 and its detection method will be described.

  In a recording head that discharges ink by applying electric pulses to a discharge heater (electrothermal conversion element) to generate bubbles in the ink, the energy of the applied voltage pulse (hereinafter also referred to as drive energy) is too low. The ejection cannot be performed normally, resulting in ejection failure. On the other hand, if the drive energy is too high, excessive energy more than necessary is applied to the discharge heater, which adversely affects the life of the discharge heater. In other words, the optimum driving condition is a threshold driving energy or a value obtained by multiplying this threshold driving energy by a safety factor so that ink can be reliably ejected and no extra energy is given to the ejection heater. is there. In actual recording, driving is performed under a condition in which a threshold driving energy has a margin as a safety factor for performing ejection. This is because, when an error that cannot be followed, such as a change in the state of the printer during continuous operation, occurs, ejection failure occurs with the threshold drive energy. In the present embodiment, driving energy is obtained by multiplying the threshold driving energy by 10% of a safety factor.

  Next, a method for detecting the optimum driving condition will be described. The recording head discharges ink by applying a voltage to a discharge heater provided for each nozzle. However, since there are variations in the manufacturing tolerance of the discharge heater, the power supply tolerance of the recording apparatus main body, the wiring resistance between the power supply and the discharge heater, it is desirable to set an optimum driving condition for each discharge heater. Here, the drive condition is set by setting the drive energy applied to the discharge heater, that is, the voltage value of the pulse to be applied or the application time thereof as described above. In this embodiment, a test pattern is recorded under a plurality of conditions with different application times of voltage pulses, and threshold drive energy as an optimum drive condition is detected based on the read result.

  FIG. 5 is a flowchart showing details of the optimum drive condition determination process in step S401 (FIG. 4). First, in step S501, inspection conditions are set. As described above, the inspection condition is the application time of the voltage pulse to the electrothermal transducer.

  FIG. 6 is a diagram showing the inspection conditions of the present embodiment. The inspection condition is set as the application time corresponding to the drive control of the printer of this embodiment in which the voltage pulse voltage is constant and the application time is changed. As shown in FIG. 6, ten inspection conditions are set as inspection conditions, in which the voltage value is constant at 24 V and the application time is gradually shortened.

  As described above, in this embodiment, the threshold driving energy is detected in the process of gradually shortening the application time, that is, decreasing the energy. This is because, in an ink jet recording apparatus, if there is a non-ejection time, the ink dries, adheres, and is difficult to eject. Therefore, the inspection conditions are changed sequentially from a long application time when the energy increases. It is possible to avoid such a problem of drying and fixing of ink by performing a preliminary discharge operation which is an ink discharge not related to the recording before the test pattern recording. Needless to say, the present invention can be applied to any inspection condition setting.

  Further, the temperature at which the printing apparatus is placed is relatively important in detecting threshold drive energy to be ejected by sequentially changing the inspection conditions. This is because when the temperature is different, the viscosity of the ink is different, and the threshold drive energy required for ejection is different. When there is a possibility that the environmental temperature of the recording device may fluctuate greatly, taking this into consideration, the difference between the standard environmental temperature and the environmental temperature at the time of inspection is detected, and the energy to be inspected based on the difference amount Conversion processing can also be performed.

  Next, in step S502, an inspection pattern is recorded. That is, each inspection pattern corresponding to the ten inspection conditions set in step S501 is recorded. As described above, this inspection pattern is recorded on the next page after the recording for one page is completed.

  FIG. 7 is a diagram for explaining the inspection pattern according to the present embodiment, and specifically shows the relationship between the nozzle arrangement in the recording head to be inspected and the inspection pattern recorded on the recording medium. . In FIG. 7, a recording head 701 includes four nozzle arrays A to 4 in order to simplify the illustration and description of the nozzle arrangement of a plurality of chips in a staggered arrangement in one ink color recording head of this embodiment. Each D is shown as a single nozzle row. In each nozzle row, individual nozzles are specified as 0 Seg, 1 Seg,. FIG. 7 shows that one nozzle row is composed of 24 nozzles for simplification of illustration.

  The recording medium 702 is conveyed with respect to the recording head 701 in the direction of the arrow in the figure, and during this conveyance, ink is ejected from the recording head 701 based on the recording data corresponding to the pattern, so that FIG. An inspection pattern as shown is recorded. That is, the inspection pattern is recorded so that the inspection patterns of the nozzle row A, the nozzle row B, the nozzle row C, and the nozzle row D are arranged on the recording medium from the downstream side in the transport direction. The inspection pattern of each nozzle row is such that ink is first ejected from nozzles of 0, 4, 8, 12, 16, 20 Seg, and then ink is ejected from 1, 5,..., 21 Seg nozzles. Further, a set of every four nozzles is a pattern for discharging at the same timing. Thereby, it is possible to easily determine the ejection failure of each nozzle.

  The inspection pattern which is one inspection unit described above is recorded for each of the ten inspection conditions determined in step S501. Also, patterns corresponding to the ten inspection conditions are recorded for each of the four ink color recording heads.

  Referring to FIG. 5 again, in the next step S503, it is determined whether or not the recording of the 10 inspection condition patterns defined in step S501 is completed. In addition, it is also determined whether or not the recording corresponding to the ten inspection conditions has been completed for all the recording heads of the four ink colors. When all the patterns have been recorded, the recorded pattern is read by the reading unit 6 in step S504. In step S505, the CPU 301 executes an analysis process on the read image of the read inspection pattern.

  FIGS. 8A, 8B, and 8C are diagrams schematically showing read images of the inspection pattern according to the present embodiment. FIGS. 8A, 8B, and 8C are different inspection conditions. It is a read image of the inspection pattern recorded in step (b). Specifically, (a), (b), and (c) correspond to the inspection conditions 1, 5, and 10 shown in FIG. In the inspection condition 1 shown in FIG. 8A, since the application time is 1.20 μsec and relatively large energy is input, all nozzles are ejected normally regardless of the secular change of each nozzle at this time. doing. In the inspection condition 5 shown in FIG. 8B, the application time is 1.00 μsec, the input energy is slightly reduced, and there are some nozzles that are not normally ejected depending on the aging of the nozzles. The nozzle that is not ejected here is, for example, a nozzle surrounded by black in the lower left part of FIG. 8B, which should be ejected originally, but is not ejected, and no pattern is recorded. Refers to that. Further, in the inspection condition 10 shown in FIG. 8C, the application time is 0.75 μsec, the input energy is reduced, and the number of nozzles that are normally discharged is very small. The nozzle is defective.

  FIG. 9 is a diagram illustrating the relationship of the number of normal ejection nozzles with respect to the inspection conditions based on the inspection pattern reading result described above, in which the horizontal axis indicates the number of inspection conditions, and the vertical axis indicates the number of normal ejection nozzles. ing. In the inspection conditions 1 to 4, all the nozzles discharge normally because there is sufficient energy to be applied to the electrothermal transducers (discharge heaters) of each nozzle. However, since the energy applied from the inspection condition 5 gradually decreases, the number of defective nozzles increases according to the aging of the nozzles at that time.

  Based on the above analysis, it is determined that the threshold driving energy corresponding to the change in the film pressure occurring in each nozzle at that time is the driving condition of 24 V, 1.05 μsec corresponding to the inspection condition 4. The actual driving condition is obtained by multiplying the voltage by 10% of a safety factor, that is, 1.1, to be 26 V, 1.05 μsec, which is the optimum driving condition. That is, the process in step S401 described above constitutes a drive condition setting process in which the drive condition is set to a drive condition that does not cause a discharge failure due to a change in the protective film in the recording head.

  In this embodiment, the safety factor is about 10%, and the voltage is corrected. However, it goes without saying that the safety factor is a value calculated based on an assumed error of the apparatus and may be set in any manner. Further, a safety factor may be applied to the application time instead of the voltage value. In the analysis of the present embodiment, it is assumed that all nozzles discharge normally except for the energy factor to be applied. However, in reality, dust such as paper dust may be mixed in the nozzle, which may cause ejection failure regardless of the applied energy. In such a case, the inspection condition 1 is used as a reference, and nozzles that have already failed to discharge at the time of the condition 1 may be excluded when determining the threshold energy. Further, when the threshold energy is determined at the time when even one nozzle is not ejected normally, there is a possibility that defective ejection caused by accidental paper dust mixing during recording cannot be handled. In such a case, a condition for determining the threshold energy may be added when a predetermined number of nozzles are not normally ejected at the time of determination. Furthermore, the optimal driving condition calculation method is, for example, to detect the amount of current without recording on the paper surface by an observation device such as a camera, in addition to the form of actually recording and inspecting as in the present embodiment, It may be a method. In short, it goes without saying that the present invention can be applied to whatever calculation method is used as the optimum driving condition calculation method.

  Referring to FIG. 4 again, in the next step S402, the initial optimum drive condition information calculated in step S401 is stored in a predetermined memory. The driving condition information may be stored in any format. In this embodiment, the application time itself of the voltage pulse of each discharge heater is recorded. However, for example, a rank may be defined for each characteristic of a heater that can be manufactured with tolerances, and the measured result may be stored as rank information. It goes without saying that the effect of the present invention can be obtained no matter what method is used. Thus, by having a function of storing the driving conditions, the driving conditions can be taken out at any time. For example, even when the power of the recording apparatus is turned off, the information stored at the next power-on can be read, and the driving conditions can be set appropriately again.

  Next, in step S403, normal recording is performed based on the optimum drive condition (optimum application time) calculated in step S401. In this recording, the number of ejections is counted for each nozzle. As will be described later, the optimum driving condition is remeasured at a predetermined interval until it is determined that the mounted recording head has a lifetime. Then, at the time of recording, the latest optimum driving condition remeasured as described above is applied to the driving of the recording head.

  Next, in step S404, it is determined whether or not it is the remeasurement timing of the driving condition. When the remeasurement timing is reached, the process proceeds to step S405. When the remeasurement timing is not reached, the process returns to step S404 to perform normal recording.

  FIGS. 10A and 10B are diagrams for explaining the relationship between the optimum driving condition and the changed protective film thickness according to the present embodiment. In the ink jet recording apparatus, as described above, a protective film is provided between the electrothermal conversion element (discharge heater) that applies the voltage pulse and the ink so as to prevent the electrothermal conversion element from being damaged. Yes. The greater the thickness of the protective film, the more difficult the energy is transferred from the electrothermal conversion element to the ink. As a result, a large amount of energy is required for ejection. That is, as shown in FIG. 10A, as the protective film thickness of the electrothermal transducer increases, the voltage pulse application time as the optimum driving condition also increases. On the other hand, when the electrothermal conversion element generates heat and ejects ink, the protective film is gradually scraped by stress (cavitation) that acts when the generated bubbles disappear. For this reason, as shown in FIG. 10B, the thickness of the protective film tends to decrease as the cumulative number of ejections increases. When the protective film thickness is reduced in this way, the optimum application time decreases as can be seen from FIG.

  Thus, it is desirable to set the optimum driving condition according to the thickness of the protective film that changes. However, there is a significant change in the thickness of the protective film, and it is not practical to use the apparatus to set the optimum driving condition at a frequency corresponding to the change. For this reason, in this embodiment, the voltage pulse related to the set optimum drive condition is used until the next optimum drive condition setting timing. In the remeasurement timing of the present embodiment, the number of discharges is counted for each discharge heater, and it is determined that the remeasurement timing has been reached when any of the discharge times exceeds a predetermined threshold. Specifically, in this embodiment, every time a predetermined number of ejections is counted, it is determined that it is the remeasurement timing of the optimum drive condition, and the optimum drive condition (second condition) is reset (second drive condition). Acquisition).

  In this embodiment, the remeasurement timing is determined based on the number of ejections, but the contact time between the protective film and the ink, that is, the ink is attached as a factor affecting the thickness of the protective film. There is also time (wearing time). This is because a chemical reaction occurs between the ink and the protective film, and the composition of the protective film surface changes. Therefore, the contact time between the protective film and the ink may be counted instead of the number of ejections, and the remeasurement timing may be based on this. Further, both the number of ejections and the contact time may be used as a reference for the remeasurement timing. Of course, the remeasurement timing may be determined using any standard. The remeasurement timing may vary depending on various conditions. For example, it may change depending on the ink physical properties of the ink type, the installation temperature of the recording apparatus, and the like. In such a case, re-measurement can be performed at a more optimal timing by grasping the amount of change in advance and changing the threshold condition at the time of determination.

  In step S404, as described above, it is determined based on the count value of the number of ejections whether or not it is a remeasurement timing. If it is time to remeasure, the optimum drive condition is remeasured in step S405. Details of the measurement have been described in step S402, and a description thereof will be omitted. In this embodiment, the voltage pulse application time as the optimum driving condition is stored as a history without being overwritten. However, when the memory capacity is limited, the head initial state may be overwritten and the remeasurement result may be updated as needed.

  Next, in step S406, the difference between the optimum driving condition remeasured in step S405 and the initial optimum driving condition of the used recording head stored in step S402 is calculated (difference value acquisition). Specifically, the difference between the optimum application time of the initial voltage pulse and the optimum application time obtained by re-measurement is obtained. In step S407, it is determined whether the difference is equal to or greater than a predetermined threshold. If it is equal to or greater than the threshold value, it is determined that the recording head has reached the end of its useful life, prompts the user to replace the recording head, and ends the process. That is, by determining in advance the amount of change in the optimum driving condition when the recording head is at the end of life and setting the amount of change as the predetermined threshold, the life of the recording head is determined by judgment based on this threshold. Can be predicted. If it is determined that the threshold value is not more than the threshold value, the processes after step S403 are repeated. Note that the drive conditions obtained by re-measurement of the latest optimum drive conditions are used as the drive conditions for normal recording. As a result, it is possible to predict and judge an accurate life of the recording head.

  In the case where the difference is equal to or greater than the specified value, the replacement of the head is promoted because the protective film is thin and there is a high possibility that the head will be broken. There are also ink types that do not cause much damage. In the case of such an ink, it is considered that there is a low possibility that the ink will be broken even if it is used with a thin protective film. Therefore, more suitable life management can be performed by changing the threshold value for prompting head replacement depending on the ink type and ink physical properties.

  Various forms of timing for determining whether or not to remeasure the driving condition in step S404 can be considered. For example, when it is desired to make the remeasurement timing strict, it is possible to constantly monitor the number of ejections during recording, and to immediately stop the recording at a timing exceeding the threshold and remeasure the drive condition. In addition, the user starts the detection process at the timing when the recording work is separated. Alternatively, it may be possible to prioritize the operating rate during the operation of the apparatus, to perform determination processing at the power-on or power-off timing every day, and to remeasure the driving conditions. It is also possible to have a function that allows the user to select and set these timings, and it is possible to more suitably manage the life of the recording head.

  The present embodiment also relates to a system that performs recording under common driving conditions even when a plurality of nozzles are present in the recording head. However, it goes without saying that the present invention is not limited to a system for recording in the head under a common driving condition. The driving conditions may be set individually for each nozzle row or each nozzle. Further, the user may be able to select the system in consideration of the processing load of the system.

  Further, in a system in which the inside of the recording head is driven under common driving conditions, there is a possibility that the ejection threshold energy in the head becomes a problem. Here, the following description will be given by calling a nozzle having a low threshold energy within the head as a nozzle that is easy to discharge and a nozzle having a high threshold energy as a nozzle that is difficult to discharge. In this embodiment, the energy is decreased to detect the ejection failure and the threshold energy is determined. The optimum driving condition is determined for the nozzle that is difficult to eject, and the driving condition is reflected in the head. . However, for nozzles that are easy to eject, energy higher than the threshold energy is the detection result. As a result, even during actual image recording, driving is performed with excess energy, and the effect of shortening the life or disconnection due to high energy is considered. Therefore, by adding the amount of variation in the head as one determination condition for urging the head replacement when determining the drive condition, it is possible to perform more preferable life management of the recording head. In addition, when variations in the recording head occur, it is possible to take measures to suppress the variations in the chip by actually ejecting nozzles that are difficult to eject by preliminary ejection or the like. Further, in the present embodiment, the optimum driving condition in the initial state of the recording head relates to a form of detecting and storing when the main body is mounted. However, for the purpose of shortening the time when the recording head is mounted, a form in which the initial state is measured at the factory when the recording head is manufactured and this information is attached to the recording head and shipped is also conceivable.

(Second Embodiment)
In the first embodiment described above, the re-measurement timing of the optimum driving condition is performed every time the predetermined number of ejections is counted, that is, at an equal interval with respect to the number of ejections within the life of the recording head. Of course, the remeasurement timing is not limited to this form. In other words, from the viewpoint of predicting and judging the life of the recording head, the number of remeasurements may be reduced at the initial stage of use of the recording head, and remeasurement may be performed with higher frequency as the recording head life approaches. The second embodiment relates to this form. Note that the basic configuration of the apparatus and the like is the same as that of the first embodiment, and a detailed description thereof will be omitted.

  FIG. 11 is a flowchart showing a process for determining an optimum driving condition of an electrothermal transducer (discharge heater) in a print head and determining the life of the print head based on the second embodiment of the present invention, It is a figure similar to FIG. 4 which concerns on 1st Embodiment.

  In FIG. 11, steps S1101 to S1102 are the same processes as steps S401 to S402 of FIG. 4 according to the first embodiment. Also, steps S1104 to S1108 are the same processes as steps S403 to S407, and description of these processes is omitted.

  Next, in step S1103, the next re-measurement timing of the optimum drive condition is set. For example, in the case of a new recording head, it is assumed that the thickness of the protective film has not decreased so much. As described above, the thickness of the protective film decreases as the number of ejections increases. Therefore, in this embodiment, as will be described later with reference to FIGS. 12 and 13, a remeasurement timing for the next optimum driving condition is set. For example, the first re-measurement timing after the initial measurement timing is when the number of ejections of the largest number of ejection heaters among the ejection heaters (nozzles) of the recording head is 50% of the number of ejections indicating the average recording head life. Is the re-measurement timing.

  If it is determined in step S1108 that the difference between the optimum driving conditions is equal to or less than the threshold value, the process returns to step S1103 to set the next remeasurement timing. Hereinafter, the method of setting the remeasurement timing according to this embodiment will be described with reference to FIGS.

  FIG. 12 is a diagram illustrating a change in the voltage pulse application time under the optimum driving condition with respect to the number of ejections. As described above, as the number of ejections increases, the thickness of the protective film decreases, and the rate of change in threshold driving energy (application time) increases. For this reason, it is desirable to set optimal driving conditions at shorter intervals as the number of ejections increases. That is, as indicated by black dots in FIG. 12, the re-measurement of the optimum driving condition is performed at shorter intervals as the number of ejections increases.

  In this embodiment, the remeasurement timing is obtained based on a difference value from the initial optimum driving condition of the recording head. FIG. 13 is a diagram showing the relationship between this difference value and the number of ejections until the next remeasurement timing. In step S1003, the number of ejections until the next remeasurement is set based on the relationship shown in FIG.

  In this way, by determining the next remeasurement timing based on the remeasurement result and the result in the initial state of the recording head, the number of inspections is reduced in the head initial state, and remeasurement is frequently performed as the life approaches. It becomes possible. As a result, the extra maintenance time required for inspection can be shortened, and the life can be accurately predicted for a recording head near the life.

1 Inkjet printer 300 Computer 301 CPU
302 ROM
303 RAM
312 scanner

Claims (10)

An ink jet recording apparatus that performs recording using a recording head that discharges ink by applying an electric pulse to an electrothermal transducer,
First driving condition acquisition means for acquiring an initial optimal driving condition of the recording head as a first condition, which is an optimal driving condition that is a condition of an electric pulse applied to the electrothermal conversion element capable of ejecting ink;
Second driving condition acquisition means for acquiring the optimum driving condition as a second condition after using the recording head;
Difference value acquisition means for obtaining a difference between the optimum driving condition of the first condition and the optimum driving condition of the second condition;
Determining means for determining whether or not the difference is equal to or greater than a predetermined threshold; if the difference is equal to or greater than the threshold, determining means for determining that the recording head has a lifetime;
An ink jet recording apparatus comprising:   The optimum driving condition of the first condition is either acquired when the recording head is mounted on the ink jet recording apparatus, or acquired when the recording head is manufactured and stored along with the recording head. The ink jet recording apparatus according to claim 1, wherein   3. The ink jet recording apparatus according to claim 1, wherein the optimum driving condition is one of a voltage value of an electric pulse applied to the electrothermal transducer and an application time. 4.   The inkjet recording apparatus according to claim 1, wherein the predetermined threshold value varies depending on a type of ink ejected from the recording head.   5. The inkjet recording apparatus according to claim 1, wherein the timing for acquiring the optimum driving condition of the second condition is determined based on the number of ejections of the recording head or the mounting time of the recording head.   6. The timing for acquiring the optimum driving condition of the second condition is set based on a difference between the optimum driving condition of the first condition and the optimum driving condition of the second condition. An ink jet recording apparatus according to any one of the above.   The timing for acquiring the optimum drive condition for the second condition is set earlier as the difference between the optimum drive condition for the first condition and the optimum drive condition for the second condition is larger. Inkjet recording device.   8. The first driving condition acquisition unit and the second driving condition acquisition unit acquire respective optimum driving conditions in consideration of an environmental temperature of the inkjet recording apparatus during recording. An ink jet recording apparatus according to any one of the above.   The variation is suppressed by driving the electrothermal transducer when the variation in the optimum drive condition of a plurality of electrothermal transducers driven under the same optimum drive condition is equal to or greater than a predetermined threshold. The ink jet recording apparatus according to claim 1. A method for determining the life of a recording head in an ink jet recording apparatus that performs recording using a recording head that discharges ink by applying an electric pulse to an electrothermal transducer,
A first driving condition acquisition step of acquiring an initial optimal driving condition of the recording head as a first condition, which is an optimal driving condition that is a condition of an electric pulse applied to the electrothermal conversion element capable of ejecting ink;
A second driving condition acquisition step of acquiring the optimum driving condition as a second condition after using the recording head;
A difference value obtaining step for obtaining a difference between the optimum driving condition of the first condition and the optimum driving condition of the second condition;
A determination step of determining whether the difference is equal to or greater than a predetermined threshold, and determining that the recording head is at the end of its life if the difference is equal to or greater than the threshold;
A life judging method characterized by comprising:

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