JP3909714B2 - Ink jet recording apparatus and preliminary discharge control method - Google Patents

Description

  The present invention relates to an ink jet recording apparatus and a preliminary ejection control method, and more particularly to a recovery operation control technique for a recording head.

  In recent years, inkjet recording apparatuses (inkjet printers) have become widespread as recording apparatuses that print and record images taken by digital still cameras. An ink jet recording apparatus includes a plurality of recording elements in a head, and scans the recording head while ejecting ink droplets from the recording elements onto the recording medium. By conveying and repeating this process, an image is formed on the recording paper.

  Inkjet printers use a single serial head and perform recording while scanning the head in the width direction of the recording medium, or a line head in which recording elements are arranged corresponding to the entire area of one side of the recording medium Some use In the case of using a line head, image recording can be performed on the entire surface of the recording medium by scanning the recording medium in a direction perpendicular to the arrangement direction of the recording elements. A printer using a line head does not require a carriage system such as a carriage that scans a short head, and does not require complicated scanning control between the movement of the carriage and the recording medium. Further, since only the recording medium moves, the recording speed can be increased as compared with a printer using a serial head.

  Ink used in inkjet printers has the property that the ink solvent (eg, mainly water in the case of water-based inks) evaporates when exposed to the atmosphere, and the viscosity of the ink gradually increases as time passes. Will cause the ink to harden. Therefore, in a nozzle that does not eject ink for a long time, first, the ink in the vicinity of the nozzle opening (the surface where the ink comes into contact with air) becomes highly viscous, and the ink inside the nozzle gradually becomes highly viscous.

  When the above-described increase in the viscosity of ink occurs, it becomes difficult for ink to be ejected from a nozzle that does not eject ink for a long time, and further, when time passes, ink is not ejected from the nozzle even if a predetermined pressure is applied. There is.

  In order to solve such problems, preliminary discharge (purge, spit discharge, idle discharge, dummy discharge) is performed at regular intervals, and the thickened ink in the nozzle is discharged to the outside, or a suction means such as a pump is used. A recovery operation is performed to suck the ink that has been hardened.

In the storage medium storing the inkjet recording apparatus, the recovery processing method, and the recovery processing program disclosed in Patent Document 1, since the nozzles to be used are determined for printing with the same content, it is not necessary to perform the recovery operation during printing. In the case of printing a plurality of sheets having the same contents, control is performed so that the recovery operation is not performed during recording. On the other hand, when the print contents are different, the time for which each nozzle is left is recorded, and if it is less than the reference, the nozzle is controlled not to perform the recovery operation. By controlling in this way, the number of preliminary ejections is reduced and the ink consumption is reduced.
JP 11-192729 A

  However, if the recovery operation is frequently performed in order to prevent ejection failure and non-ejection, not only the ink consumption increases, but the productivity of practical prints may decrease. Moreover, since the recovery means for performing the recovery operation includes consumable parts such as blades, maintenance of these consumable parts is required.

  In the storage medium storing the inkjet recording apparatus, the recovery processing method, and the recovery processing program disclosed in Patent Document 1, nozzles that are not used for printing are used when a large amount of printing is performed at once even if the same contents are printed. Is not used for a long time, the ink in the nozzle is completely solidified (very high viscosity / thickening from the nozzle opening to the deep portion), and the nozzle may not be recovered only by preliminary ejection. obtain. Further, when considering a long print, if the standing time is checked before printing, it may exceed the reference time until ink thickening occurs during printing and an ejection failure occurs.

  Therefore, defective ejection or non-ejection of the nozzles occurs, and the print result may cause unevenness in the conveyance direction of the recording medium. The above-mentioned problems become particularly noticeable in a single path using a line head.

  The present invention has been made in view of such circumstances, and provides an inkjet recording apparatus and a preliminary ejection control method capable of reliably recovering nozzles and suppressing ink consumption due to the recovery operation. Objective.

In order to achieve the above object, an invention according to claim 1 is an ink jet recording apparatus that performs printing by ejecting ink droplets onto a recording medium using a recording head provided with a nozzle for ejecting ink droplets. In the preliminary discharge determination timing for determining whether or not to perform preliminary discharge from the end of image printing to the start of printing of the next image for the nozzle, the preliminary discharge determination timing after the nozzle is operated last time. And a non-operating scheduled time from the preliminary ejection determination timing to the next printing is calculated from the print data of the next image and the conveyance speed of the recording medium. And when the sum of the non-operating time and the non-operating scheduled time exceeds a reference time at the preliminary discharge determination timing, It is characterized by preliminary ejection of Le is provided with a preliminary discharge control means for controlling to execute.

  That is, when the total time of the non-operating time from the previous nozzle operation to the present (the past) and the planned non-operation time from the current operation to the next nozzle exceeds the reference time, the preliminary discharge is executed. Controlled. Therefore, it is possible to prevent a discharge abnormality from occurring in the nozzle during printing.

  The operation of the nozzles may include recovery operations such as preliminary ejection and nozzle suction in addition to ink ejection during printing.

  When ink is discharged (discharged) from the nozzle due to operation, preliminary discharge, suction, etc., the non-operation time measurement value is reset (initialized), and the next non-operation time is newly measured from the reset time. .

  The non-working time may include an interval time between images and a time of a blank portion.

The preliminary ejection determination timing for determining whether or not to perform preliminary ejection may be when printing of each image is started or when printing of each lot (print job) is started. Further, when the determination is made for each lot, the control may be performed so that the determination is made for each image in the lot or at an arbitrary timing for the long-time lot. According to a second aspect of the present invention, in the invention according to the first aspect, the reference time is a time from the previous ejection of the nozzle to the occurrence of abnormal ejection of ink ejected from the nozzle. Yes. According to a third aspect of the present invention, in the first or second aspect of the invention, the reference time is determined according to at least one of an ink type and a use environment condition of the recording head. Yes.

  The recording head may be a full-line type printing head in which ink discharge ports (nozzle openings) are arranged over the entire printable area of the recording medium to be printed in a direction substantially orthogonal to the recording medium conveyance direction. However, the line type print head may be divided into a plurality of divided heads. Furthermore, a shuttle scan type print head that discharges ink droplets while moving a short print head in a direction substantially orthogonal to the print medium conveyance direction may be used. A combined type of a line type head and a shuttle scan type head may be used.

  Preliminary discharge (purge, spit discharge, idle discharge, dummy discharge) is a case where the frequency of use of a specific nozzle is low during printing or standby, and if no ink is discharged for a certain period of time, the ink solvent near the nozzle Evaporates to increase the ink viscosity. In such a state, ink cannot be ejected from the nozzle even if the actuator operates.

  Before this condition is reached (within the range of viscosity that can be discharged by the operation of the actuator), the actuator is operated to discharge the deteriorated ink (the ink in the vicinity of the nozzle with increased viscosity). The ink ejection may be performed when the power is turned on (at the time of resetting) or every predetermined period, or may be performed as necessary by detecting the droplet ejection result.

  The reference time may be set for each nozzle or may be set for each of a plurality of nozzles. Further, it may be set for the entire recording head. Further, when a plurality of recording heads are provided, they may be set for each recording head or may be set for all the heads.

  In this specification, the term “printing” represents not only the formation of characters but also the concept of forming an image in a broad sense including characters.

According to a fourth aspect of the present invention, there is provided an ink jet recording apparatus for performing printing by ejecting ink droplets onto a recording medium using a recording head provided with a nozzle for ejecting ink droplets. In the preliminary discharge determination timing for determining whether or not to perform preliminary discharge from the end of image printing to the start of printing of the next image for the nozzle, the preliminary discharge is performed after the nozzle is operated last time. A calculation means for calculating a non-operation time until a determination timing; and for the nozzle, a non-operation scheduled time from the preliminary discharge determination timing to the next printing is determined, the print data of the next image and the conveyance speed of the recording medium And the non-operating time and the non-operating pre-estimation for the nozzle that is scheduled to operate in the next image at the preliminary discharge determination timing. When the total time exceeds a first reference time, preliminary ejection of the nozzle is executed, and a predetermined time is set as the scheduled non-operation time for a nozzle that is not scheduled to operate in the next image. Pre-discharge control means for performing control so that pre-discharge of the nozzle is executed when the total of the predetermined time exceeds a second reference time.

  That is, it is determined whether or not to perform preliminary ejection based on the first reference time for nozzles that are scheduled to operate and the second reference time for nozzles that are not scheduled to operate. The necessity of preliminary ejection can be determined according to whether the nozzle is activated or not, and the ink consumed by the preliminary ejection can be reduced.

  If two reference times are used such that the first reference time is smaller than the second reference time, the number of preliminary ejections can be reduced for nozzles that are not scheduled to operate compared to nozzles that are scheduled to operate.

  The first reference time and the second reference time may be set for each nozzle or may be set for each of a plurality of nozzles. Further, it may be set for the entire recording head. Further, when a plurality of recording heads are provided, they may be set for each recording head or may be set for all the heads.

  Since a non-operating scheduled time cannot be calculated for a nozzle that is not scheduled to operate, a predetermined time (value) is set instead of the non-operating scheduled time. The predetermined time may be 0, or a value obtained by a predetermined calculation may be set. The mode for obtaining the predetermined time may be an average value of past non-working time or a predicted value obtained by predicting non-working time from the past history. Further, if the predetermined time is set to 0, it is determined whether or not the preliminary ejection is performed based only on the non-operation time.

In order to achieve the above object, the invention according to claim 5 is an inkjet recording apparatus that performs printing by ejecting ink droplets onto a recording medium using a recording head provided with a nozzle for ejecting ink droplets. In the preliminary discharge determination timing for determining whether or not to perform preliminary discharge from the end of image printing to the start of printing of the next image for the nozzle, the preliminary discharge is performed after the nozzle is operated last time. A calculation means for calculating a non-operation time until a determination timing; and for the nozzle, a non-operation scheduled time from the preliminary discharge determination timing to the next printing is determined, the print data of the next image and the conveyance speed of the recording medium And the non-operating time and the non-operating schedule for the nozzle operated in the next image at the preliminary discharge determination timing. When the total of the interval exceeds the first reference time, the preliminary discharge of the nozzle is executed, and in the nozzle that is not operated in the next image, the trailing edge of the next image is determined from the non-operation time and the preliminary discharge determination timing. And a preliminary discharge control unit that performs control so that the preliminary discharge of the nozzle is executed when the total time until printing is completed exceeds a second reference time.

  That is, in the nozzle operated in the next image, the preliminary discharge is executed when the sum of the non-operating time from the previous nozzle operation and the scheduled time until the nozzle operation exceeds the first reference time. In a nozzle that is not operated by an image, since the sum of the non-operating time and the time until the printing of the trailing edge of the next image exceeds the second reference time, control is performed so that preliminary ejection is executed. The necessity of preliminary discharge is determined according to the operation and non-operation of the nozzle according to the contents, and furthermore, there are multiple reference times according to the operation and non-operation of the nozzle, and whether or not preliminary discharge is performed is controlled by these. The Therefore, the number of preliminary ejections can be suppressed, and the ink consumed by the preliminary ejection can be reduced.

According to a sixth aspect of the present invention, in the invention according to the fourth or fifth aspect , the preliminary ejection control unit is configured to perform printing of the first image with the nozzle to be operated in a plurality of printing of the same content image. When the sum of the non-operating time and the scheduled non-operating time exceeds a first reference time, preliminary ejection of the nozzle is executed, and when the nozzle is not operated, the non-operating time and the non-operating time are printed. Control is performed so that the preliminary ejection of the corresponding nozzle is executed when the sum of the time until the trailing edge of the next image is printed exceeds the second reference time during the next image printing. It is characterized by that.

  That is, since frequent preliminary ejection is not performed during printing, it is possible not only to print a preferable image without reducing productivity, but also to suppress ink consumption due to preliminary ejection.

Further, in the invention according to 4, 5 or 6, wherein as shown in claim 7, the pre-Symbol first reference time, from the previous ejection of the nozzles to the discharge abnormality of the ink occurs ejected from the nozzle It is characterized by the time.

  The discharge abnormality includes a discharge amount abnormality in which an amount of ink different from the originally discharged ink amount is discharged and a discharge direction abnormality in which ink is discharged in a direction different from the original discharge direction. In addition, the occurrence of splash is included in the ejection abnormality. If these discharge abnormalities occur, the quality of the printed result may be degraded.

  The criterion for determining whether or not there is a discharge abnormality is determined in consideration of variations in ink discharge and discharge direction.

Further, according to an eighth aspect of the present invention, in the invention according to any one of the fourth to seventh aspects, the ink is ejected from the nozzle by the predetermined driving from the previous ejection of the nozzle during the second reference time. It is a time until non-ejection that is not performed occurs.

  The non-ejection may be a state in which the ink cannot be ejected even if a predetermined pressure is applied to the ink, or even if a maximum pressure that can be output by a drive source (actuator) that applies pressure to the ink is applied to the ink. A state where ink cannot be ejected may be used.

  Since the nozzle that has failed to be ejected cannot be recovered by preliminary ejection, a recovery operation such as suction by a pump is performed. It is necessary to perform the preliminary discharge before the ejection failure, that is, while the nozzle can be recovered by the preliminary discharge.

Further, in the invention described in any one of claims 9 to show way claims 4 to 8, before Symbol the first reference time and the second reference time, the ink type and the recording head It is characterized in that it is determined according to at least one of the usage environment conditions.

  Ink types include dye-based inks and pigment-based inks, and the components differ depending on the type of ink, and the time until thickening starts and the speed of thickening differ. Further, the time until thickening starts and the speed of thickening differ depending on the use environment conditions such as use temperature and humidity.

  When the time to start thickening becomes early or when the progress of thickening becomes faster, the reference time, the first reference time, and the second reference time may be set shorter than usual.

According to a tenth aspect of the present invention, in the invention according to any one of the first to ninth aspects, the recording head includes a plurality of the nozzles, and the preliminary ejection control means performs a preliminary operation for each nozzle. It is characterized by controlling the discharge. In order to achieve the above object, the invention according to claim 11 is provided with a plurality of nozzles for ejecting ink droplets, and two or more nozzles are used as one block, and the plurality of nozzles are divided into a plurality of blocks. An ink jet recording apparatus that performs printing by ejecting ink droplets onto a recording medium using a recording head, and performs preliminary ejection from the end of image printing to the start of printing of the next image for each nozzle. In the preliminary discharge determination timing for determining whether or not, the calculation means for calculating the non-operation time of each nozzle from the previous operation of each nozzle to the preliminary discharge determination timing, and for each nozzle from the preliminary discharge determination timing a calculation means for the non-operational expected time until the next printing, is calculated from the conveying speed of the next image of the print data and the recording medium The storage means stores the non-operating time of each nozzle determined by the calculating means, the scheduled non-operating time of each nozzle determined by the calculating means, and is stored in the storage means at the preliminary discharge determination timing. Based on the non-operating time of each nozzle and the scheduled non-operating time of each nozzle, the longest non-operating time among the non-operating times of two or more nozzles included in each block is set as the non-operating time of the block, the longest non-operational schedule time of the non-operational expected time of 2 or more nozzles included in each block is set to non-operation scheduled time of the block, the non-operating with the previous SL non-operational time period for each block that has been set Pre-discharge control means for performing control so that pre-discharge of all the nozzles in the block is executed when the total of the scheduled time exceeds a reference time. It is. According to a twelfth aspect of the present invention, in the invention according to the eleventh aspect, the reference time is a time from the previous ejection of the nozzle to the occurrence of abnormal ejection of ink ejected from the nozzle. It is said. According to a thirteenth aspect of the present invention, in the invention according to the eleventh or twelfth aspect, the reference time is determined according to at least one of an ink type and a use environment condition of the recording head. It is said. In order to achieve the above object, the invention according to claim 14 is provided with a plurality of nozzles for ejecting ink droplets, and the plurality of nozzles are divided into a plurality of blocks with two or more nozzles as one block. An ink jet recording apparatus that performs printing by ejecting ink droplets onto a recording medium using a recording head, and performs preliminary ejection from the end of image printing to the start of printing of the next image for each nozzle. In the preliminary discharge determination timing for determining whether or not, the calculation means for calculating the non-operation time of each nozzle from the previous operation of each nozzle to the preliminary discharge determination timing, and for each nozzle from the preliminary discharge determination timing a calculation means for the non-operational expected time until the next printing, is calculated from the conveying speed of the next image of the print data and the recording medium The storage means stores the non-operating time of each nozzle determined by the calculating means, the scheduled non-operating time of each nozzle determined by the calculating means, and is stored in the storage means at the preliminary discharge determination timing. based on the non-operational time period and the non-operational estimated time of each nozzle of each nozzle, when there is the operational schedule of nozzles in each block in the next image, the non-operating time of two or more nozzles included in each block The longest non-operation time is set as the non-operation time of the block, and the longest non-operation time of the two or more nozzles included in each block is set as the non-operation time of the block. set, before Symbol total preliminary discharge of all nozzles in the block exceeds the first reference time and non-operational time period and the non-operational schedule time for each block that has been set Is executed, if there is no operation schedule of all the nozzles in said each block in the next image, the non-operation time of the block a longest non-operating time of the non-operating time of two or more nozzles included in each block a and sets the predetermined time is set as a non-operational schedule time for each block, the sum of the previous SL non-operational time period and said predetermined time of each block is set greater than the second reference time Pre-discharge control means for performing control so that pre-discharge of all nozzles in the block is executed. In order to achieve the above object, the invention according to claim 15 is provided with a plurality of nozzles for ejecting ink droplets, and two or more nozzles are used as one block, and the plurality of nozzles are divided into a plurality of blocks. An ink jet recording apparatus that performs printing by ejecting ink droplets onto a recording medium using the recording head, and performs preliminary ejection from the end of image printing to the start of printing of the next image for each nozzle. In the preliminary discharge determination timing for determining whether or not to perform, a calculation means for calculating a non-operation time of each nozzle from the previous operation of each nozzle to the preliminary discharge determination timing, and the preliminary discharge determination timing for each nozzle calculating means for the non-operational expected time until the next printing, it is calculated from the conveying speed of the next image of the print data and the recording medium from the The storage means stores the non-operation time of each nozzle determined by the calculation means, the scheduled non-operation time of each nozzle determined by the calculation means, and is stored in the storage means at the preliminary discharge determination timing. that on the basis of the non-operational time period and the non-operational estimated time of each nozzle of each nozzle, when there is the operational schedule of nozzles in each block in the next image, the non-operation of two or more nozzles included in each block The longest non-operation time of the time is set as the non-operation time of the block, and the longest non-operation time of the two or more nozzles included in each block is set as the non-operation time of the block. set to, preliminary ejection of all nozzles in the block and the sum of the previous SL non-operational time period and the non-operational schedule time for each block that has been set is greater than the first reference time There is performed, if there is no operation schedule of all the nozzles in said each block in the next image, the non-operation of the block the longest non-operating time of the non-operating time of two or more nozzles included in each block and sets time, exceeds the total second reference time and the time from the preliminary discharge judgment timing before and Symbol non-operational time period for each block that has been set until after printing the rear end portion of the next image In this case, the apparatus is characterized by comprising preliminary discharge control means for performing control so that preliminary discharge of all the nozzles in the block is executed. Further, according to a sixteenth or fifteenth aspect of the present invention, in the invention according to the fourteenth or fifteenth aspect, the first reference time is a time from the previous ejection of the nozzle to the occurrence of abnormal ejection of ink ejected from the nozzle. It is characterized by being. Further, according to a seventeenth, fifteenth, or sixteenth aspect of the present invention, the second reference time is a period from the previous ejection of the nozzle until a non-ejection in which ink is not ejected by a predetermined drive. It is characterized by time. According to an eighteenth aspect of the present invention, in the invention according to any one of the fourteenth to seventeenth aspects, the first reference time and the second reference time are the type of ink and the use of the recording head. It is characterized by being determined according to at least one of the environmental conditions. The present invention also provides a method invention for achieving the above object. That is, the invention according to claim 19 is a preliminary ejection control method in an ink jet recording apparatus that performs printing by ejecting ink droplets onto a recording medium using a recording head provided with a nozzle for ejecting ink droplets. A calculation step of calculating a non-operating time of the nozzle until a preliminary discharge determination timing for determining whether or not to perform preliminary discharge from the previous operation of the nozzle to the start of image printing. , A calculation step of calculating a non-operation scheduled time from the preliminary discharge determination timing to the next printing for the nozzle from the print data of the next image and the conveyance speed of the recording medium, and the timing of the preliminary discharge determination The total of the non-operation time calculated in the calculation step and the non-operation scheduled time calculated in the calculation step Is characterized by comprising a preliminary discharge step of preliminary discharge of the nozzle is executed exceeds the reference time, the.

  Preferably, an identification step for identifying a nozzle that is scheduled for the next operation and a nozzle that is not scheduled for the next operation is provided, and in the nozzle that is scheduled for the next operation, the non-operation time and the non-operation schedule in the preliminary discharge step When the total time exceeds the first reference time, preliminary discharge of the nozzle is executed, and in the preliminary discharge step, the non-operating time and the trailing edge of the next image are printed in the preliminary discharge process. This is a mode in which the nozzle is controlled so that the preliminary discharge is executed when the sum of the time until the time exceeds the second reference time.

  The relationship between the first reference time and the second reference time is as follows: first reference time <second reference time.

In order to achieve the above object, an invention according to claim 20 is an ink jet recording apparatus that performs printing by ejecting ink droplets onto a recording medium using a recording head provided with a nozzle for ejecting ink droplets. In the preliminary discharge control method, the nozzle is inactive until the preliminary discharge determination timing for determining whether or not to perform preliminary discharge from the previous operation of the nozzle to the start of image printing. A calculation step of calculating a time, and a calculation step of calculating a non-operation scheduled time from the preliminary ejection determination timing to the next printing for the nozzle from the print data of the next image and the conveyance speed of the recording medium; At the timing for determining the preliminary discharge, the total of the non-operating time and the non-operating scheduled time is the first for the nozzle operated in the next image. When the reference time is exceeded, preliminary ejection of the nozzle is executed, while for a nozzle that is not operated in the next image, a predetermined time is set as the non-operating time, and the sum of the non-operating scheduled time and the predetermined time is And a preliminary discharge step in which the preliminary discharge of the nozzle is executed when the second reference time is exceeded.

  That is, since the preliminary ejection reference is provided for the nozzles that are not scheduled to be operated next time, the preliminary ejection can be performed at a preferable timing.

In order to achieve the above object, an invention according to claim 21 is an ink jet recording apparatus that performs printing by ejecting ink droplets onto a recording medium using a recording head provided with a nozzle for ejecting ink droplets. In the preliminary discharge control method, the nozzle is inactive until the preliminary discharge determination timing for determining whether or not to perform preliminary discharge from the previous operation of the nozzle to the start of image printing. A calculation step of calculating a time, and a calculation step of calculating a non-operation scheduled time from the preliminary ejection determination timing to the next printing for the nozzle from the print data of the next image and the conveyance speed of the recording medium; At the timing for determining the preliminary discharge, the total of the non-operating time and the non-operating scheduled time is the first for the nozzle operated in the next image. When the reference time is exceeded, preliminary ejection of the nozzle is executed, while for the nozzle that is not operated in the next image, the sum of the non-operation time and the time from the present to the end of printing the rear end of the next image is the first. And a preliminary discharge step in which the preliminary discharge of the nozzle is executed when a reference time of 2 is exceeded.

  That is, the nozzles that are not scheduled to be operated next time are reliably pre-discharged.

  According to the present invention, it is determined whether or not to perform preliminary discharge from the sum of the non-operation time from the previous nozzle operation to the present and the scheduled non-operation time from the present to the next nozzle operation. As a result, the nozzles operating during printing do not cause ejection failure.

  Further, two parameters are provided for the reference time for performing the preliminary ejection, and the reference time can be properly used depending on the nozzle operated in the next image and the nozzle not operated in the next image. Accordingly, the number of preliminary ejections can be reduced, and the amount of ink consumed by the preliminary ejection can be reduced. In the conventional technique, since the preliminary ejection is controlled with respect to the first reference (ejection abnormality) of the present invention, the ink consumption cannot be reduced.

  In multiple-sheet printing with the same content, the nozzles that are activated and the nozzles that are not activated are determined. Therefore, in the nozzles that are activated, it is determined whether or not preliminary ejection is performed when the first sheet is printed. It is determined whether or not preliminary ejection is performed for each printing. Therefore, the number of preliminary ejections can be reduced, and ejection abnormalities and non-ejections can be avoided.

  One of the two reference times is a time until an ejection abnormality (a state where ink is ejected but not normal ejection) can occur, and the other is a non-ejection (in normal control, ink cannot be ejected from a nozzle) A mode in which the time until the state is reached is preferable.

  It is preferable that the reference time for performing preliminary ejection is determined so as to be optimized for each type of ink, ink color, and usage environment (temperature, humidity, atmospheric pressure, etc.).

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[Overall configuration of inkjet recording apparatus]
FIG. 1 is an overall configuration diagram of an ink jet recording apparatus according to an embodiment of the present invention. As shown in the figure, the inkjet recording apparatus 10 includes a print unit 12 having a plurality of print heads 12K, 12C, 12M, and 12Y provided for each ink color, and each print head 12K, 12C, 12M, An ink storage / loading unit 14 for storing ink to be supplied to 12Y, a paper feeding unit 18 for supplying recording paper 16, a decurling unit 20 for removing curling of the recording paper 16, and a nozzle of the printing unit 12 A suction belt transport unit 22 that is disposed to face a surface (ink ejection surface) and transports the recording paper 16 while maintaining the flatness of the recording paper 16, and a print detection unit 24 that reads a printing result by the printing unit 12, A paper discharge unit 26 that discharges printed recording paper (printed matter) to the outside.

  In FIG. 1, a magazine for rolled paper (continuous paper) is shown as an example of the paper supply unit 18, but a plurality of magazines having different paper widths, paper quality, and the like may be provided side by side. Further, instead of the roll paper magazine or in combination therewith, the paper may be supplied by a cassette in which cut papers are stacked and loaded.

  When multiple types of recording paper are used, an information recording body such as a barcode or wireless tag that records paper type information is attached to the magazine, and the information on the information recording body is read by a predetermined reader. Therefore, it is preferable to automatically determine the type of paper to be used and perform ink ejection control so as to realize appropriate ink ejection according to the type of paper.

  The recording paper 16 delivered from the paper supply unit 18 retains curl due to having been loaded in the magazine. In order to remove this curl, heat is applied to the recording paper 16 by the heating drum 30 in the direction opposite to the curl direction of the magazine in the decurling unit 20. At this time, it is more preferable to control the heating temperature so that the printed surface is slightly curled outward.

  In the case of an apparatus configuration that uses roll paper, a cutter (first cutter) 28 is provided as shown in FIG. 1, and the roll paper is cut into a desired size by the cutter 28. The cutter 28 includes a fixed blade 28A having a length equal to or greater than the conveyance path width of the recording paper 16, and a round blade 28B that moves along the fixed blade 28A. The fixed blade 28A is provided on the back side of the print. The round blade 28B is disposed on the printing surface side with the conveyance path interposed therebetween. Note that the cutter 28 is not necessary when cut paper is used.

  After the decurling process, the cut recording paper 16 is sent to the suction belt conveyance unit 22. The suction belt conveyance unit 22 has a structure in which an endless belt 33 is wound between rollers 31 and 32, and at least portions facing the nozzle surface of the printing unit 12 and the sensor surface of the printing detection unit 24 are horizontal ( Flat surface).

  The belt 33 has a width that is wider than the width of the recording paper 16, and a plurality of suction holes (not shown) are formed on the belt surface. As shown in FIG. 1, a suction chamber 34 is provided at a position facing the nozzle surface of the print unit 12 and the sensor surface of the print detection unit 24 inside the belt 33 spanned between the rollers 31 and 32. Then, the suction chamber 34 is sucked by the fan 35 to be a negative pressure, whereby the recording paper 16 on the belt 33 is sucked and held.

  When the power of a motor (not shown in FIG. 1, not shown in FIG. 8) is transmitted to at least one of the rollers 31 and 32 around which the belt 33 is wound, the belt 33 rotates in the clockwise direction in FIG. , And the recording paper 16 held on the belt 33 is conveyed from left to right in FIG.

  Since ink adheres to the belt 33 when a borderless print or the like is printed, the belt cleaning unit 36 is provided at a predetermined position outside the belt 33 (an appropriate position other than the print area). Although details of the configuration of the belt cleaning unit 36 are not shown, for example, there are a method of niping a brush roll, a water absorbing roll, etc., an air blow method of blowing clean air, or a combination thereof. In the case where the cleaning roll is nipped, the cleaning effect is great if the belt linear velocity and the roller linear velocity are changed.

  Although a mode using a roller / nip conveyance mechanism instead of the suction belt conveyance unit 22 is also conceivable, if the roller / nip conveyance is performed in the print area, the image easily spreads because the roller contacts the printing surface of the sheet immediately after printing. There is a problem. Therefore, as in this example, suction belt conveyance that does not bring the image surface into contact with each other in the print region is preferable.

  A heating fan 40 is provided on the upstream side of the printing unit 12 on the paper conveyance path formed by the suction belt conveyance unit 22. The heating fan 40 blows heated air on the recording paper 16 before printing to heat the recording paper 16. Heating the recording paper 16 immediately before printing makes it easier for the ink to dry after landing.

  The printing unit 12 is a so-called full line type head in which line type heads having a length corresponding to the maximum paper width are arranged in a direction (main scanning direction) orthogonal to the paper feed direction (see FIG. 2). Although a detailed structural example will be described later (FIGS. 3 to 5), each of the print heads 12K, 12C, 12M, and 12Y is a recording paper of the maximum size targeted by the inkjet recording apparatus 10 as shown in FIG. The line head includes a plurality of ink discharge ports (nozzles) arranged over a length exceeding at least one side of 16.

  A print head 12K corresponding to each color ink in the order of black (K), cyan (C), magenta (M), and yellow (Y) from the upstream side along the feeding direction of the recording paper 16 (hereinafter referred to as the paper transport direction). , 12C, 12M, 12Y are arranged. A color image can be formed on the recording paper 16 by discharging the color inks from the print heads 12K, 12C, 12M, and 12Y while the recording paper 16 is conveyed.

  Thus, according to the printing unit 12 in which the full line head that covers the entire area of the paper width is provided for each ink color, the operation of relatively moving the recording paper 16 and the printing unit 12 in the sub-scanning direction is performed once. An image can be recorded on the entire surface of the recording paper 16 only by performing it (that is, by one sub-scan). Thereby, it is possible to perform high-speed printing as compared with a shuttle type head in which the print head reciprocates in the main scanning direction, and productivity can be improved.

  In this example, the configuration of KCMY standard colors (four colors) is illustrated, but the combination of ink colors and the number of colors is not limited to this embodiment, and light ink and dark ink are added as necessary. May be. For example, it is possible to add a print head that discharges light ink such as light cyan and light magenta.

  As shown in FIG. 1, the ink storage / loading unit 14 has tanks that store inks of colors corresponding to the print heads 12K, 12C, 12M, and 12Y, and each tank is connected via a conduit (not shown). The print heads 12K, 12C, 12M, and 12Y communicate with each other. Further, the ink storage / loading unit 14 includes notifying means (display means, warning sound generating means) for notifying when the ink remaining amount is low, and has a mechanism for preventing erroneous loading between colors. ing.

  The print detection unit 24 includes an image sensor for imaging the droplet ejection result of the print unit 12, and functions as a means for checking nozzle clogging and other ejection defects from the droplet ejection image read by the image sensor.

  The print detection unit 24 of this example is composed of a line sensor having a light receiving element array that is wider than at least the ink ejection width (image recording width) by the print heads 12K, 12C, 12M, and 12Y. The line sensor includes an R sensor row in which photoelectric conversion elements (pixels) provided with red (R) color filters are arranged in a line, a G sensor row provided with green (G) color filters, The color separation line CCD sensor is composed of a B sensor array provided with a blue (B) color filter. Instead of the line sensor, an area sensor in which the light receiving elements are two-dimensionally arranged can be used.

  The print detection unit 24 reads the test pattern printed by the print heads 12K, 12C, 12M, and 12Y for each color, and detects the ejection of each head. The ejection determination includes the presence / absence of ejection, measurement of dot size, measurement of dot landing position, and the like. Details of discharge detection will be described later.

  A post-drying unit 42 is provided following the print detection unit 24. The post-drying unit 42 is means for drying the printed image surface, and for example, a heating fan is used. Since it is preferable to avoid contact with the printing surface until the ink after printing is dried, a method of blowing hot air is preferred.

  When printing on porous paper with dye-based ink, the weather resistance of the image is improved by preventing contact with ozone or other things that cause dye molecules to break by blocking the paper holes by pressurization. There is an effect to.

  A heating / pressurizing unit 44 is provided following the post-drying unit 42. The heating / pressurizing unit 44 is a means for controlling the glossiness of the image surface, and pressurizes with a pressure roller 45 having a predetermined surface uneven shape while heating the image surface to transfer the uneven shape to the image surface. To do.

  The printed matter generated in this manner is outputted from the paper output unit 26. It is preferable that the original image to be printed (printed target image) and the test print are discharged separately. The ink jet recording apparatus 10 is provided with a sorting means (not shown) that switches the paper discharge path so as to select the print product of the main image and the print product of the test print and send them to the discharge units 26A and 26B. Yes. Note that when the main image and the test print are simultaneously formed in parallel on a large sheet, the test print portion is separated by a cutter (second cutter) 48. The cutter 48 is provided immediately before the paper discharge unit 26, and cuts the main image and the test print unit when the test print is performed on the image margin. The structure of the cutter 48 is the same as that of the first cutter 28 described above, and includes a fixed blade 48A and a round blade 48B.

  Although not shown in FIG. 1, the paper output unit 26A for the target prints is provided with a sorter for collecting prints according to print orders.

  Next, the structure of the print head will be described. Since the structures of the print heads 12K, 12C, 12M, and 12Y provided for the respective ink colors are common, the print heads are represented by reference numeral 50 in the following.

  FIG. 3 (a) is a plan perspective view showing an example of the structure of the print head 50, and FIG. 3 (b) is an enlarged view of a part thereof. 3C is a perspective plan view showing another example of the structure of the print head 50, and FIG. 4 is a cross-sectional view showing the three-dimensional configuration of the ink chamber unit (along line 4-4 in FIG. 3A). FIG. In order to increase the dot pitch printed on the recording paper surface, it is necessary to increase the nozzle pitch in the print head 50. As shown in FIGS. 3A to 3C and FIG. 4, the print head 50 of this example includes a plurality of inks including nozzles 51 from which ink droplets are ejected and pressure chambers 52 corresponding to the nozzles 51. The chamber units 53 have a structure in which the chamber units 53 are arranged in a staggered matrix, thereby achieving an increase in the apparent nozzle pitch density.

  That is, in the print head 50 according to the present embodiment, as shown in FIGS. 3A and 3B, the plurality of nozzles 51 that eject ink correspond to the entire width of the print medium in a direction substantially orthogonal to the print medium feed direction. This is a full line head having one or more nozzle rows arranged over a length of the same.

  Further, as shown in FIG. 3 (c), short two-dimensionally arranged heads 50 'may be arranged in a staggered manner and connected to form a length corresponding to the entire width of the print medium.

  The pressure chamber 52 provided corresponding to each nozzle 51 has a substantially square planar shape, and the nozzle 51 and the supply port 54 are provided at both corners on the diagonal line. Each pressure chamber 52 communicates with a common flow channel 55 through a supply port 54.

  An actuator 58 having an individual electrode 57 is joined to the pressure plate 56 constituting the top surface of the pressure chamber 52, and the actuator 58 is deformed by applying a driving voltage to the individual electrode 57, and the nozzle 51 Ink is ejected. When ink is ejected, new ink is supplied from the common channel 55 to the pressure chamber 52 through the supply port 54.

  As shown in FIG. 5, a large number of ink chamber units 53 having such a structure are arranged in a row direction along the main scanning direction and an oblique column direction having a constant angle θ that is not orthogonal to the main scanning direction. The structure is arranged in a lattice pattern. With a structure in which a plurality of ink chamber units 53 are arranged at a constant pitch d along a certain angle θ with respect to the main scanning direction, the pitch P of the nozzles projected so as to be aligned in the main scanning direction is d × cos θ. .

  That is, in the main scanning direction, each nozzle 51 can be handled equivalently as a linear arrangement with a constant pitch P. With such a configuration, it is possible to realize a high-density nozzle configuration in which 2400 nozzle rows are projected per inch (2400 nozzles / inch) so as to be aligned in the main scanning direction. Hereinafter, for convenience of explanation, it is assumed that the nozzles 51 are linearly arranged at a constant interval (pitch P) along the longitudinal direction (main scanning direction) of the head.

  When the nozzles are driven with a full line head having a nozzle row corresponding to the entire width of the paper (recording paper 16), (1) all the nozzles are driven simultaneously, (2) the nozzles are sequentially moved from one side to the other. (3) The nozzles are divided into blocks, and each block is sequentially driven from one side to the other. One row of dots is formed in the paper width direction (direction perpendicular to the paper conveyance direction). Nozzle driving that prints a line or a line composed of a plurality of rows of dots is defined as main scanning.

  When driving the nozzles 51 arranged in a matrix as shown in FIG. 3A, the main scanning as described in the above (3) is preferable. That is, one line is printed in the width direction of the recording paper 16 by driving the nozzle 51A and the nozzle 51B at different timings according to the conveyance speed of the recording paper 16 like the nozzles 51A, 51B, 51A,.

  On the other hand, the sub-scan is defined as the above-described full-line head and the paper are moved relative to each other to repeatedly print a line composed of one row of dots or a line composed of a plurality of rows of dots formed by the above-described main scan. To do.

  In the implementation of the present invention, the nozzle arrangement structure is not limited to the illustrated example. In the present embodiment, a method of ejecting ink droplets by deformation of an actuator 58 typified by a piezo element (piezoelectric element) is adopted. However, in the practice of the present invention, the method of ejecting ink is not particularly limited. Instead of the piezo jet method, various methods such as a thermal jet method in which ink is heated by a heating element such as a heater to generate bubbles and ink droplets are ejected by the pressure can be applied.

  FIG. 6 is a schematic diagram showing the configuration of the ink supply system in the inkjet recording apparatus 10.

  The ink supply tank 60 is a base tank for supplying ink, and is installed in the ink storage / loading unit 14 described with reference to FIG. There are two types of ink supply tank 60: a system that replenishes ink from a replenishment port (not shown) and a cartridge system that replaces the entire tank when the remaining amount of ink is low. A cartridge system is suitable for changing the ink type according to the intended use. In this case, it is preferable that the ink type information is identified by a barcode or the like, and ejection control is performed according to the ink type. The ink supply tank 60 in FIG. 6 is equivalent to the ink storage / loading unit 14 in FIG. 1 described above.

  As shown in FIG. 6, a filter 62 is provided between the ink supply tank 60 and the print head 50 in order to remove foreign substances and bubbles. The filter mesh size is preferably equal to or smaller than the nozzle diameter (generally about 20 μm).

  Although not shown in FIG. 6, a configuration in which a sub tank is provided in the vicinity of the print head 50 or integrally with the print head 50 is also preferable. The sub-tank has a function of improving a damper effect and refill that prevents fluctuations in the internal pressure of the head.

  Further, the inkjet recording apparatus 10 is provided with a cap 64 as a means for preventing the nozzle 51 from drying or preventing an increase in ink viscosity near the nozzle, and a cleaning blade 66 as a nozzle surface cleaning means.

  The maintenance unit including the cap 64 and the cleaning blade 66 can be moved relative to the print head 50 by a moving mechanism (not shown), and is moved from a predetermined retracted position to a maintenance position below the print head 50 as necessary. The

  The cap 64 is displaced up and down relatively with respect to the print head 50 by an elevator mechanism (not shown). The cap 64 is raised to a predetermined raised position when the power is turned off or during printing standby, and is brought into close contact with the print head 50, thereby covering the nozzle surface with the cap 64.

  During printing or standby, if the frequency of use of a specific nozzle 51 is reduced and ink is not ejected for a certain period of time, the ink solvent near the nozzle evaporates and the ink viscosity increases. In such a state, ink cannot be ejected from the nozzle 51 even if the actuator 58 operates.

  Before such a state is reached (within the range of the viscosity that can be discharged by the operation of the actuator 58), the actuator 58 is operated, and the cap 64 (ink near the nozzle whose viscosity has increased) is discharged. Preliminary ejection (purging, idle ejection, collar ejection, dummy ejection) is performed toward the ink receiver.

  Further, when air bubbles are mixed into the ink in the print head 50 (in the pressure chamber 52), the ink cannot be ejected from the nozzle even if the actuator 58 is operated. In such a case, the cap 64 is applied to the print head 50, the ink in the pressure chamber 52 (ink mixed with bubbles) is removed by suction with the suction pump 67, and the suctioned and removed ink is sent to the collection tank 68. .

  In this suction operation, the deteriorated ink with increased viscosity (solidified) is sucked out when the ink is initially loaded into the head or when the ink is used after being stopped for a long time. Since the suction operation is performed on the entire ink in the pressure chamber 52, the amount of ink consumption increases. Therefore, it is preferable to perform preliminary ejection when the increase in ink viscosity is small.

  The cleaning blade 66 is made of an elastic member such as rubber, and can slide on the ink discharge surface (surface of the nozzle plate) of the print head 50 by a blade moving mechanism (wiper) (not shown). When ink droplets or foreign substances adhere to the nozzle plate, the nozzle plate surface is wiped by sliding the cleaning blade 66 on the nozzle plate to clean the nozzle plate surface. It should be noted that when the ink ejection surface is cleaned by the blade mechanism, preliminary ejection is performed in order to prevent foreign matter from being mixed into the nozzle 51 by the blade.

  FIG. 7 is a principal block diagram showing the system configuration of the inkjet recording apparatus 10. The inkjet recording apparatus 10 includes a communication interface 70, a system controller 72, a memory 74, a motor driver 76, a heater driver 78, a print control unit 80, an image buffer memory 82, a head driver 84, and the like.

  The communication interface 70 is an interface unit that receives image data sent from the host computer 86. As the communication interface 70, a serial interface such as USB (Universal Serial Bus), IEEE 1394, Ethernet (registered trademark), a wireless network, or a parallel interface such as Centronics can be applied. In this part, a buffer memory (not shown) for speeding up communication may be mounted. The image data sent from the host computer 86 is taken into the inkjet recording apparatus 10 via the communication interface 70 and temporarily stored in the memory 74. The memory 74 is a storage unit that temporarily stores an image input via the communication interface 70, and data is read and written through the system controller 72. The memory 74 is not limited to a memory made of a semiconductor element, and a magnetic medium such as a hard disk may be used.

  The system controller 72 is a control unit that controls the communication interface 70, the memory 74, the motor driver 76, the heater driver 78, and the like. The system controller 72 includes a central processing unit (CPU) and its peripheral circuits, and performs communication control with the host computer 86, read / write control of the memory 74, and the like, and controls the motor 88 and heater 89 of the transport system. A control signal to be controlled is generated.

  The motor driver 76 is a driver (drive circuit) that drives the motor 88 in accordance with an instruction from the system controller 72. The heater driver 78 is a driver that drives the heater 89 such as the post-drying unit 42 in accordance with an instruction from the system controller 72.

  The print control unit 80 has a signal processing function for performing various processing and correction processing for generating a print control signal from image data in the memory 74 in accordance with the control of the system controller 72, and the generated print control. A control unit that supplies a signal (print data) to the head driver 84. Necessary signal processing is performed in the print controller 80, and the ejection amount and ejection timing of the ink droplets of the print head 50 are controlled via the head driver 84 based on the image data. Thereby, a desired dot size and dot arrangement are realized.

  The print control unit 80 includes an image buffer memory 82, and image data, parameters, and other data are temporarily stored in the image buffer memory 82 when image data is processed in the print control unit 80. In FIG. 7, the image buffer memory 82 is shown in a mode associated with the print control unit 80, but it can also be used as the memory 74. Also possible is an aspect in which the print controller 80 and the system controller 72 are integrated and configured with a single processor.

  The head driver 84 drives the actuators of the print heads 12K, 12C, 12M, and 12Y for each color based on the print data given from the print control unit 80. The head driver 84 may include a feedback control system for keeping the head driving conditions constant.

  Various control programs are stored in the program storage unit 90, and the control programs are read and executed in accordance with instructions from the system controller 72. The program storage unit 90 may use a semiconductor memory such as a ROM or an EEPROM, or may use a magnetic disk or the like. An external interface may be provided and a memory card or PC card may be used. Of course, you may provide several recording media among these recording media.

  The program storage unit 90 may also be used as a recording means (not shown) for operating parameters.

  As described with reference to FIG. 1, the print detection unit 24 is a block including a line sensor, reads an image printed on the recording paper 16, performs necessary signal processing, and the like to perform a print status (whether ejection is performed, droplet ejection And the detection result is provided to the print control unit 80.

  The print control unit 80 performs various corrections on the print head 50 based on information obtained from the print detection unit 24 as necessary.

  In the example shown in FIG. 1, the print detection unit 24 is provided on the print surface side, and the print surface is illuminated by a light source (not shown) such as a cold cathode tube disposed in the vicinity of the line sensor. Although the configuration is such that the reflected light is read by the line sensor, other configurations may be used in the implementation of the present invention.

  The inkjet recording apparatus 10 includes a nozzle management memory 92 in which management information for each nozzle is recorded. The nozzle management information recorded in the nozzle management memory 92 includes the operation time and non-operation time of each nozzle (the operation results of each nozzle), and image data (image information) recorded in the memory 74 or the image buffer memory 82. From the system controller 72 and the print control unit 80, the scheduled operation time and non-operation scheduled time of each nozzle, the reference time for performing preliminary discharge of each nozzle, and the like are included.

  In addition to these pieces of information, various information such as locality information of each nozzle may be recorded in the nozzle management memory.

  The preliminary discharge control unit 94 in the print control unit 80 grasps the state of each nozzle based on the nozzle information recorded in the nozzle management memory 92 and determines that nozzle maintenance such as preliminary discharge is necessary. A predetermined instruction signal is sent to the head driver 84 and the maintenance unit 96.

  The execution determination of the maintenance operation described above relates to the temperature and humidity in the apparatus, particularly in the vicinity of the print head 50. When the temperature in the vicinity of the print head 50 is increased, the thickening of the ink in the non-operating nozzle and the drying of the ink in the vicinity of the meniscus are promoted. Further, when the humidity is lowered, drying of the ink near the meniscus is promoted. The inkjet recording apparatus 10 includes a temperature / humidity detection unit 98 that measures the temperature and humidity of each unit in the apparatus, and the temperature / humidity information obtained by the temperature / humidity detection unit 98 is sent to the print control unit 80.

  The print control unit 80 (preliminary ejection control unit 94) performs control such as changing the reference time for preliminary ejection based on the temperature information and humidity information obtained in this way.

[Preliminary discharge control]
In general, in an ink jet recording apparatus, preliminary ejection is periodically performed to prevent ejection failure or non-ejection of the nozzles 51. By regularly performing preliminary discharge, ink droplets are normally discharged from the nozzle 51, and a predetermined print quality can be ensured. However, frequent preliminary ejection not only reduces the productivity of practical prints but also consumes wasted ink.

  In order to solve such a problem, the inkjet recording apparatus 10 is controlled to perform preliminary ejection at a preferable timing.

  FIG. 8 shows a preliminary discharge reference time in the ink jet recording apparatus 10. The ink jet recording apparatus 10 has two parameters for the preliminary discharge reference time. One of the two parameters is ejection in which splash starts to occur after the ink in the nozzle 51 is ejected, or ink droplet flying direction (ejection direction) abnormality or ink droplet size (ejection amount) abnormality begins to occur. The time Tng1 until the abnormality is detected, and the other is the time Tng2 until ink discharge is impossible from the nozzle 51 with the pressure applied to the ink by driving the actuator 58 shown in FIG.

  Here, an example of criteria for determining abnormal discharge and non-discharge is shown below.

  When the center of the droplet ejection point that is actually ejected with respect to the center of the target position (originally ejected position) is at a distance of 1.5 times or less of the droplet ejection pitch, it is regarded as normal droplet ejection. If it is off, it is determined that the discharge is abnormal.

  Further, when a plurality of droplets are landed in a range that is twice or more the original droplet size, it is determined that the ejection is abnormal, and a state in which no droplets are ejected from the nozzle 51 is determined as non-ejection. Note that the above-described determination criteria for abnormal discharge and non-ejection are examples, and other determination criteria can be applied.

  The above-described Tng1 and Tng2 depend on the type of ink (ink viscosity), the lot of ink, the use environment (temperature, humidity, atmospheric pressure) of the print head 50, and the environmental history. A configuration that can be changed according to the above is preferable.

  For example, when the viscosity of the ink itself varies depending on the type of ink, Tng1 and Tng2 are set to small values for the ink with high viscosity. The ink cartridge is equipped with a wireless tag or barcode that records ink information (ink viscosity), and is configured to read the ink information recorded on the wireless tag or barcode when the ink cartridge is replaced. From the information, Tng1 and Tng2 can be set by the system controller 72 shown in FIG.

  In addition, as the temperature increases, the ink thickens more rapidly, and when the humidity decreases, the meniscus surface tends to be easily dried. It is possible to read the temperature and humidity from the temperature / humidity detection unit 98 shown in FIG. 7, and Tng1 and Tng2 can be set according to the temperature and humidity.

  It is also possible to store Tng1 and Tng2 set in the past, obtain an average value thereof at a predetermined timing, and change the setting of Tng1 and Tng2 based on the average value.

  In addition, when a piezoelectric element such as a piezo is used for the actuator 58, the actuator 58 gives a slight vibration to the ink in the pressure chamber 52 before the ink thickens and becomes non-ejection. The ink is agitated, and the increase in the viscosity of the meniscus surface (the boundary surface between the ink and the atmosphere in the nozzle 51 discharge hole) can be delayed.

  Tu1 and Tu2 shown in FIG. 8 are times during which Tng1 and Tng2 can be delayed by the slight vibration of the ink.

  The timing for giving the minute vibration may be before Tng1 is exceeded or before Tng1 is exceeded and Tng2 is exceeded. Further, the fine vibration may be applied at a timing independent of the preliminary discharge control. In addition, it is preferable that the drive waveform when giving fine vibration to the ink is a trapezoidal waveform or a rectangular wave. Furthermore, it is necessary to perform control so that ink leakage does not occur from the nozzles by fine vibration control.

  That is, when a slight vibration is applied to the ink in the pressure chamber 52, the time until ejection abnormality is the total time of Tng1 and Tu1, and the time until non-ejection is the total time of Tng2 and Tu2. Tu1 and Tu2 depend on the type of ink used, the ink lot, the usage environment such as temperature, humidity, and atmospheric pressure, and the environmental history.

  On the other hand, when a thermal type actuator is used, since it is difficult to perform the above-described control for giving a slight vibration to the ink, preliminary ejection is almost always performed for ink thickening.

  FIG. 9 shows the timing of preliminary ejection control of the inkjet recording apparatus 10. In printing the previous image 100, at timing Ta, droplet ejection at the droplet ejection point 102 on the previous image 100 is performed from an arbitrary nozzle 51A in the print head 50.

  The preliminary discharge determination timing Tb from the end of printing of the image 100 to the start of printing of the next image 110 is a timing for determining whether or not to perform preliminary discharge of the nozzle 51A. (Time from the timing Ta to Tb at which droplet ejection is performed from the nozzle 51A) is measured (stored), and from Tb to the timing Tc of the next droplet ejection point 112 ejected from the nozzle 51A in the next image 110. The scheduled non-operation time T2 is calculated. In the non-operation time T1, for example, if the nozzle 51A is operated for the previous image and the nozzle 51A is not operated for the previous image, the elapsed time from the operation of the previous nozzle 51A Become. T1 and T2 include a waiting time (including a margin) between images.

  The non-operation time T1 is obtained by the system controller 72 and the print controller 80. The nozzle management memory 92 shown in FIG. 7 is applied to the memory (storage means) used for temporarily storing the non-operating time T1 and the non-operating scheduled time T2.

  Further, the droplet ejection position on the image of each nozzle is obtained from the input print data, the droplet ejection timing is obtained from the conveyance speed of the recording paper, and the estimated non-operation time T2 is obtained.

  When the total time of the non-operating time T1 and the scheduled non-operating time T2 of the nozzle 51A measured at the timing Tb in FIG. 9 exceeds the preliminary discharge time Tng1 shown in FIG. Discharge is performed.

  FIG. 10 shows an aspect of the next image 110 when the nozzle 51A is not operated (no droplets are ejected from the nozzle 51A).

  In the next image 110, when the nozzle 51A is not operated, a time T21 from Tb to the print timing Td of the rear end portion 114 of the next image 110 is calculated. The total time of the non-operation time T1 (the same definition as T1 described in FIG. 9) and the time T21 from Tb to the printing timing Td of the rear end portion 114 of the next image 110 is Tng2 shown in FIG. When exceeding, the preliminary discharge is executed at the timing Tb in FIG.

  Further, when the nozzle 51A is not operated in the next image 110, the non-operation time T1 and the time T21 until the rear end portion 114 of the next image 110 is printed without using the nozzle 51A for printing the next image 110. When the total time does not exceed Tng2, the measurement (storage) of the non-operation time T1 is continued as shown in FIG. Further, when the nozzle 51A is operated for printing the next image 120 (droplet ejection at the droplet ejection point 122), the non-operation time T1 and the non-operation scheduled time T2 are obtained.

  When performing preliminary discharge, it is preferable to set the discharge pressure to be higher than that of normal discharge (normal printing). By increasing the discharge pressure, the thickened ink can be discharged efficiently.

  FIG. 12 is a flowchart showing the flow of preliminary ejection control (normal preliminary ejection control) of the inkjet recording apparatus 10.

  When printing is started (step S10), the process proceeds to step S12 to identify whether or not the nozzle 51A is used (operated) in the next image. When the nozzle 51A is not used in the next image (NO determination), the next nozzle operating time is set as the time until the image rear end printing, and the time T21 until the image rear end printing is calculated (step S14). ), It is determined whether or not the total time of the non-operation time T1 of the nozzle 51A and the time T21 until the image trailing edge printing exceeds the preliminary ejection reference time Tng2 (step S16).

  In step S16, when the total time of the non-operation time T1 and the time T21 until image rear end printing does not exceed Tng2 shown in FIG. 8 (NO determination), printing (image formation) is executed (FIG. 12 (step S26), when the total time of the non-working time T1 and the time T21 until the image rear end printing exceeds the preliminary discharge reference time Tng2 (YES determination), preliminary discharge is executed (step S24). .

  When the preliminary ejection is executed in step S24, the non-operation time T1 is reset (initialized) (T1 = 0 is set), and the process proceeds to step S26 where printing is executed.

  When a predetermined printing process is executed in step S26, the process proceeds to step S28, and the preliminary ejection control is terminated. When the nozzle is activated in the printing process, T1 is reset.

  On the other hand, when the nozzle 51A is used in the next image in step S12 (YES determination), a time T2 (scheduled non-operation time) T2 until the next use of the nozzle 51A is calculated (step S20). Whether the total time of the non-operating time T1 and the scheduled non-operating time T2 exceeds Tng1 shown in FIG. 8 is determined (step S22 in FIG. 12).

  In step S22, if the total time of the non-operating time T1 of the nozzle 51A and the scheduled non-operating time T2 does not exceed Tng1 (NO determination), printing is performed (step S26), and the non-operating time T1 of the nozzle 51A is performed. If the total time of the non-operation scheduled time T2 exceeds Tng1 (YES determination), the process proceeds to step S24, and preliminary ejection is executed.

  In the present embodiment, an example in which the timing Tb is before the next image printing is illustrated, but it may be before the start of printing for each lot. Further, in a lot (such as large-scale printing) in which the printing time is long, it may be determined whether or not preliminary ejection is performed at an appropriate timing within the lot.

  As described above, the values of T1, T2, and T21 for each nozzle are managed by the print control unit 80 shown in FIG. 7 and stored in the nozzle management memory 92, and the preliminary discharge control unit 94 sets Tng1 and Tng2. And the preliminary discharge is controlled. Therefore, data management for all nozzles of the head is performed.

  Next, the preliminary ejection control when printing a plurality of images having the same content will be described with reference to FIG. In FIG. 13, parts that are the same as or similar to those in FIG. 12 are given the same reference numerals, and descriptions thereof are omitted.

  When printing multiple sheets of the same image, the nozzles to be activated and the nozzles to be deactivated are determined. Therefore, for the nozzles to be activated, preliminary ejection is performed based on Tng1 shown in FIG. When Tng2 shown in FIG. 8 is exceeded by the end of the image, preliminary ejection is performed to prevent complete non-ejection of the nozzles. When printing multiple sheets of the same image, preliminary ejection may not be performed depending on the length and number of prints.

  When printing is started (step S100), the process proceeds to step S102, where the total time of the non-working time T1 and the non-working scheduled time T2 shown in FIG. 9 is calculated and whether multiple sheets of the same image are printed. It is determined whether or not.

  If it is not printing a plurality of sheets of the same image (NO determination), the normal preliminary discharge control shown in FIG. 12 is executed (step S110), and when the control of step S110 ends, the process proceeds to step S144, Is terminated.

  If it is determined in step S102 that multiple sheets of the same image are printed (YES determination), the process proceeds to step S120, and the total time of the non-operation time T1 and the non-operation scheduled time T2 shown in FIG. Is calculated, and it is determined whether or not the total time of the next image exceeds Tng1 shown in FIG.

  If it is determined in step S120 in FIG. 13 that the total time does not exceed Tng1 in the next image, the process proceeds to step S128, and the total time of the non-operation time T1 and the scheduled non-operation time T2 during printing is shown in FIG. It is determined whether or not Tng2 shown in FIG.

  In step S128, if the total time does not exceed Tng2 (NO determination), printing is executed (step S140), and the process proceeds to step S142 to check whether printing of a predetermined number (N) has been completed. To be judged. If printing of N sheets is not completed (NO determination), the process proceeds to step S128. If printing of N sheets is completed (YES determination), the preliminary ejection control is ended (step S144).

  On the other hand, if the total time exceeds Tng2 in step S128 (YES determination), preliminary ejection of the corresponding nozzle is executed (step S130), the non-operation time T1 is reset (step S132), and step S140. Proceed to

  If it is determined in step S120 that the total time exceeds Tng1 in the next image, the process proceeds to step S122, and it is determined whether or not the corresponding nozzle is a nozzle to be operated (used nozzle). In step S122, when the corresponding nozzle is not the nozzle to be operated (NO determination), the process proceeds to step S128. When the corresponding nozzle is the nozzle to be operated (YES determination), preliminary discharge of the corresponding nozzle is executed. (Step S124), T1 is reset (Step S126), and the process proceeds to Step S128.

  In long printing or the like, a mode in which the nozzles to be operated are controlled so as not to cause abnormal discharge after the second sheet is preferable.

  The inkjet recording apparatus 10 configured as described above includes a time Tng1 until a discharge abnormality occurs and a time Tng2 until a non-discharge occurs as a reference time for determining whether or not to perform preliminary discharge. The preliminary ejection is controlled based on the determination reference time. That is, since there are two time parameters until the preliminary ejection, ejection abnormalities and non-ejections can be prevented, and ink consumption can be suppressed.

  Further, the non-operation time T1 from the previous operation for each nozzle and the non-operation scheduled time T2 until the next operation are calculated, and the total time of the non-operation time T1 and the non-operation scheduled time T2 is Tng1. When exceeding, preliminary discharge is performed. For a nozzle that is not operated in the next image, a time T21 until the rear end printing of the image is calculated, and if the total time of the non-operation time T1 and the time T21 until the image rear end printing exceeds Tng2, Discharge is performed.

  Before printing, it is judged whether or not the preliminary discharge limit time (time during which normal ejection can be performed without performing preliminary ejection) is exceeded within the next printing, so that it is possible to prevent ejection abnormalities during printing and not to operate. It is also possible to prevent the nozzle from being discharged.

  The above is an example in which the non-operation time T1, the non-operation scheduled time T2, and the time T21 until the image rear end printing are controlled for each nozzle.

  On the other hand, the control may be such that a plurality of nozzles are handled as one block. For example, a line head having 10,000 nozzles per color is divided into 100 blocks, and 100 nozzles per block are collectively controlled for preliminary ejection.

  In this case, the non-operation time T1 is counted up based on the time when the nozzle is first driven in the previous image among the nozzles in the target block. The scheduled non-operation time T2 is input as the scheduled time until the last driving among all the nozzles in the block of interest in the next image. When there is no ejection schedule for all nozzles in the block of interest in the next image, the time T21 until the next image rear end printing is reached.

  In this way, T1, T2, and T21 are set to the strictest conditions in units of blocks, thereby avoiding printing defects (defective droplet size and flying direction) and reducing the load on the control system and memory. is there. Furthermore, T1, T2, and T21 may be set to the strictest conditions for the entire print head, and preliminary ejection control may be performed.

  In the present embodiment, control for determining whether or not preliminary ejection is performed for each printing (image) is exemplified, but control may be performed so as to determine whether or not preliminary ejection is performed for each of a plurality of printings.

  In the present embodiment, a full-line type print head is exemplified, but the scope of application of the present invention is not limited to this, and the present invention can also be applied to a shuttle scan type print head. Conventionally, with a shuttle scan type print head, preliminary discharge is forcibly performed from all nozzles at regular intervals, but it is determined whether the preliminary discharge reference time is exceeded before starting the next scan. It is possible to control so that the preliminary discharge is selectively performed only from the nozzle to be performed.

  Further, in this embodiment, a piezo method using a piezoelectric element for ejecting ink droplets is illustrated, but the present invention includes an energy generator in a pressure chamber, and the energy generator generates heat by heating ink in the pressure chamber. The present invention can also be applied to a thermal ink jet recording apparatus that discharges ink using bubbles.

1 is a basic configuration diagram of an ink jet recording apparatus according to an embodiment of the present invention. FIG. 1 is a plan view of the main part around the printing of the ink jet recording apparatus shown in FIG. Plane perspective view showing structural example of print head Enlarged view of the main part of Fig. 3 (a) Plane perspective view showing another structural example of the print head Sectional view along line 4-4 in Fig. 3 (a) Enlarged view showing the nozzle arrangement of the print head shown in FIG. Schematic diagram showing the configuration of the ink supply unit in the inkjet recording apparatus according to the present embodiment Main part block diagram which shows the system configuration | structure of the inkjet recording device which concerns on this embodiment. The figure explaining the preliminary discharge reference time in the preliminary discharge control of the inkjet recording apparatus according to the present embodiment The figure explaining each timing in the preliminary discharge control of the inkjet recording device which concerns on this embodiment The figure explaining the timing of the preliminary discharge control of the nozzle which is not operated The figure explaining the timing of the preliminary discharge control in the multi-sheet printing A flowchart showing a flow of preliminary ejection control of the ink jet recording apparatus according to the present embodiment. Flow chart showing the flow of preliminary discharge control for printing multiple sheets of the same content

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Inkjet recording device, 50 ... Print head, 51, 51A ... Nozzle, 58 ... Actuator, 72 ... System controller, 74 ... Memory, 90 ... Program storage part, 100 ... Previous image, 110, 120 ... Next image, T1 ... non-operation time, T2 ... scheduled non-operation time, T21 ... time until image rear end printing, Tng1 ... time until ejection abnormality, Tng2 ... time until non-ejection

Claims (21)

An inkjet recording apparatus that performs printing by ejecting ink droplets onto a recording medium using a recording head provided with a nozzle that ejects ink droplets,
In the preliminary discharge determination timing for determining whether or not to perform preliminary discharge from the end of image printing to the start of printing of the next image for the nozzle, from the previous operation of the nozzle to the preliminary discharge determination timing. A computing means for computing non-working time;
For the nozzle, a calculation means for calculating a non-operation scheduled time from the preliminary ejection determination timing to the next printing from the print data of the next image and the conveyance speed of the recording medium;
Preliminary discharge control means for performing control so that preliminary discharge of the nozzle is executed when the total of the non-operating time and the scheduled non-operating time exceeds a reference time at the preliminary discharge determination timing;
An ink jet recording apparatus comprising:   The ink jet recording apparatus according to claim 1, wherein the reference time is a time from a previous discharge of the nozzle to a discharge abnormality of the ink discharged from the nozzle.   3. The ink jet recording apparatus according to claim 1, wherein the reference time is determined according to at least one of an ink type and a use environment condition of the recording head. An inkjet recording apparatus that performs printing by ejecting ink droplets onto a recording medium using a recording head provided with a nozzle that ejects ink droplets,
In the preliminary discharge determination timing for determining whether or not to perform preliminary discharge from the end of image printing to the start of printing of the next image for the nozzle, from the previous operation of the nozzle to the preliminary discharge determination timing. A computing means for computing non-working time;
For the nozzle, a calculation means for calculating a non-operation scheduled time from the preliminary ejection determination timing to the next printing from the print data of the next image and the conveyance speed of the recording medium;
At the preliminary discharge determination timing, when the total of the non-operating time and the non-operating scheduled time exceeds a first reference time for the nozzle scheduled to operate in the next image, the nozzle is pre-discharged and the next For a nozzle that is not scheduled to operate in the image, a predetermined time is set as the scheduled non-operating time, and when the sum of the non-operating time and the predetermined time exceeds a second reference time, preliminary ejection of the nozzle is executed. Preliminary discharge control means for performing control so that
An ink jet recording apparatus comprising: An inkjet recording apparatus that performs printing by ejecting ink droplets onto a recording medium using a recording head provided with a nozzle that ejects ink droplets,
In the preliminary discharge determination timing for determining whether or not to perform preliminary discharge from the end of image printing to the start of printing of the next image for the nozzle, from the previous operation of the nozzle to the preliminary discharge determination timing. A computing means for computing non-working time;
For the nozzle, a calculation means for calculating a non-operation scheduled time from the preliminary ejection determination timing to the next printing from the print data of the next image and the conveyance speed of the recording medium;
At the preliminary discharge determination timing, when the total of the non-operating time and the scheduled non-operating time exceeds the first reference time, the nozzle is operated for the next image, and the nozzle is pre-discharged, and the next For a nozzle that is not operated by an image, if the sum of the non-operation time and the time from the preliminary discharge determination timing until the trailing edge of the next image is printed exceeds a second reference time, the preliminary discharge of the nozzle is performed. Preliminary discharge control means for performing control to be executed;
An ink jet recording apparatus comprising:   The preliminary ejection control unit is configured such that, when a plurality of images having the same contents are printed, the sum of the non-operating time and the non-operating scheduled time when the first nozzle prints the first image is first. When a reference time is exceeded, preliminary ejection of the nozzles is executed, and in the case of nozzles that are not operated, the total of the non-operating time and the time until printing of the rear end of the next image is completed when printing of each image is performed. 6. The ink jet recording apparatus according to claim 4, wherein when the second reference time exceeds the second reference time during the next image printing, control is performed so that the preliminary ejection of the corresponding nozzle is executed.   The ink jet recording apparatus according to claim 4, wherein the first reference time is a time from a previous discharge of the nozzle to a discharge abnormality of ink discharged from the nozzle.   8. The method according to claim 4, wherein the second reference time is a time from a previous ejection of the nozzle until a non-ejection in which ink is not ejected from the nozzle due to a predetermined drive. 8. The inkjet recording apparatus according to Item.   9. The method according to claim 4, wherein the first reference time and the second reference time are determined according to at least one of an ink type and a use environment condition of the recording head. 2. An ink jet recording apparatus according to item 1. The recording head has a plurality of the nozzles,
The inkjet recording apparatus according to claim 1, wherein the preliminary ejection control unit controls preliminary ejection for each nozzle. A plurality of nozzles for ejecting ink droplets are provided, and ink droplets are ejected onto a recording medium using a recording head in which two or more nozzles are used as one block and the plurality of nozzles are divided into a plurality of blocks. An inkjet recording apparatus that performs printing,
For each nozzle, at the preliminary discharge determination timing for determining whether or not to perform preliminary discharge between the end of image printing and the start of printing of the next image, the period from the previous operation of each nozzle to the preliminary discharge determination timing is determined. A calculation means for calculating the non-operation time of each nozzle;
For each nozzle, a calculation means for calculating a non-operation scheduled time from the preliminary ejection determination timing to the next printing from the print data of the next image and the conveyance speed of the recording medium;
Storage means for storing the non-operating time of each nozzle determined by the calculating means, and the scheduled non-operating time of each nozzle determined by the calculating means;
At the preliminary discharge determination timing, the longest non-operating time of two or more nozzles included in each block is based on the non-operating time of each nozzle and the scheduled non-operating time of each nozzle stored in the storage unit. The operation time is set as the non-operation time of the block, and the longest non-operation time of the two or more nozzles included in each block is set as the non-operation time of the block. a preliminary discharge control means for performing control so before Symbol sum exceeds the reference time and the preliminary discharge of all nozzles in the block of the non-operational time period and the non-operational schedule time is performed for each block has,
An ink jet recording apparatus comprising:   12. The ink jet recording apparatus according to claim 11, wherein the reference time is a time from a previous discharge of a nozzle to an occurrence of an abnormal discharge of ink discharged from the nozzle.   13. The ink jet recording apparatus according to claim 11, wherein the reference time is determined according to at least one of an ink type and a use environment condition of the recording head. A plurality of nozzles for ejecting ink droplets are provided, and ink droplets are ejected onto a recording medium using a recording head in which two or more nozzles are used as one block and the plurality of nozzles are divided into a plurality of blocks. An inkjet recording apparatus that performs printing,
For each nozzle, at the preliminary discharge determination timing for determining whether or not to perform preliminary discharge between the end of image printing and the start of printing of the next image, the period from the previous operation of each nozzle to the preliminary discharge determination timing is determined. A calculation means for calculating the non-operation time of each nozzle;
For each nozzle, a calculation means for calculating a non-operation scheduled time from the preliminary ejection determination timing to the next printing from the print data of the next image and the conveyance speed of the recording medium;
Storage means for storing the non-operating time of each nozzle determined by the calculating means, and the scheduled non-operating time of each nozzle determined by the calculating means;
In the preliminary discharge judgment timing, based on the non-operational time period and the non-operational estimated time of each nozzle of each nozzle stored in the storage means, when there is the operational schedule of nozzles in each block in the next image The longest non-operation time of two or more nozzles included in each block is set as the non-operation time of the block, and the longest non-operation time of two or more nozzles included in each block long non-operational schedule time is set to non-operation scheduled time of the block, the block with the sum of the previous SL non-operational time period and the non-operational schedule time for each block that has been set is greater than the first reference time the pre-ejection execution of all the nozzles of, if there is no operation schedule of all the nozzles in said each block in the next image, among the non-operational time period of two or more nozzles included in each block top A long non-operational time period and sets a non-operation time of the block, the predetermined time is set as a non-operational schedule time for each block, before Symbol non-operational time period of each block is set to a predetermined time Preliminary discharge control means for performing control so that preliminary discharge of all the nozzles in the block is executed when the total of the second reference time exceeds the second reference time;
An ink jet recording apparatus comprising: A plurality of nozzles for ejecting ink droplets are provided, and ink droplets are ejected onto a recording medium using a recording head in which two or more nozzles are used as one block and the plurality of nozzles are divided into a plurality of blocks. An inkjet recording apparatus that performs printing,
For each nozzle, at the preliminary discharge determination timing for determining whether or not to perform preliminary discharge between the end of image printing and the start of printing of the next image, the period from the previous operation of each nozzle to the preliminary discharge determination timing is determined. A calculation means for calculating the non-operation time of each nozzle;
For each nozzle, a calculation means for calculating a non-operation scheduled time from the preliminary ejection determination timing to the next printing from the print data of the next image and the conveyance speed of the recording medium;
Storage means for storing the non-operating time of each nozzle determined by the calculating means, and the scheduled non-operating time of each nozzle determined by the calculating means;
In the preliminary discharge judgment timing, based on the non-operational time period and the non-operational estimated time of each nozzle of each nozzle stored in the storage means, when there is the operational schedule of nozzles in each block in the next image The longest non-operation time of two or more nozzles included in each block is set as the non-operation time of the block, and the longest non-operation time of two or more nozzles included in each block long non-operational schedule time is set to non-operation scheduled time of the block, the block with the sum of the previous SL non-operational time period and the non-operational schedule time for each block that has been set is greater than the first reference time the pre-ejection execution of all the nozzles of, if there is no operation schedule of all the nozzles in said each block in the next image, among the non-operational time period of two or more nozzles included in each block top Sets a long non-operational time period and the non-operational time period of the block, time from the preliminary discharge judgment timing before and Symbol non-operational time period for each block that has been set until after printing the rear end portion of the next image When the sum of the above exceeds a second reference time, preliminary discharge control means for performing control so that preliminary discharge of all the nozzles in the block is executed,
An ink jet recording apparatus comprising:   16. The ink jet recording apparatus according to claim 14, wherein the first reference time is a time from a previous discharge of a nozzle to an occurrence of an abnormal discharge of ink discharged from the nozzle.   17. The ink jet recording apparatus according to claim 14, wherein the second reference time is a time from a previous ejection of a nozzle to a non-ejection in which ink is not ejected by a predetermined drive.   18. The method according to claim 14, wherein the first reference time and the second reference time are determined according to at least one of an ink type and a use environment condition of the recording head. 2. An ink jet recording apparatus according to item 1. A preliminary ejection control method in an inkjet recording apparatus that performs printing by ejecting ink droplets onto a recording medium using a recording head provided with nozzles that eject ink droplets,
For the nozzle, a calculation step of calculating a non-operation time of the nozzle until a preliminary discharge determination timing for determining whether or not to perform preliminary discharge after the nozzle is operated last time until image printing is started,
For the nozzle, a calculation step of calculating a non-operation scheduled time from the preliminary ejection determination timing to the next printing from the print data of the next image and the conveyance speed of the recording medium;
When the sum of the non-operation time calculated in the calculation step and the scheduled non-operation time calculated in the calculation step exceeds a reference time at the timing of determining the preliminary discharge, the preliminary discharge of the nozzle is executed. A preliminary ejection process;
The preliminary discharge control method characterized by including. A preliminary ejection control method in an inkjet recording apparatus that performs printing by ejecting ink droplets onto a recording medium using a recording head provided with nozzles that eject ink droplets,
For the nozzle, a calculation step of calculating a non-operation time of the nozzle until a preliminary discharge determination timing for determining whether or not to perform preliminary discharge after the nozzle is operated last time until image printing is started,
For the nozzle, a calculation step of calculating a non-operation scheduled time from the preliminary ejection determination timing to the next printing from the print data of the next image and the conveyance speed of the recording medium;
In the preliminary discharge determination timing, when the total of the non-operation time and the non-operation scheduled time exceeds the first reference time in the nozzle operated in the next image, the preliminary discharge of the nozzle is executed, For a nozzle that is not operated in the next image, a predetermined time is set as the non-operating time, and when the sum of the scheduled non-operating time and the predetermined time exceeds a second reference time, the preliminary discharge of the nozzle is executed. A preliminary ejection step,
The preliminary discharge control method characterized by including. A preliminary ejection control method in an inkjet recording apparatus that performs printing by ejecting ink droplets onto a recording medium using a recording head provided with nozzles that eject ink droplets,
For the nozzle, a calculation step of calculating a non-operation time of the nozzle until a preliminary discharge determination timing for determining whether or not to perform preliminary discharge after the nozzle is operated last time until image printing is started,
For the nozzle, a calculation step of calculating a non-operation scheduled time from the preliminary ejection determination timing to the next printing from the print data of the next image and the conveyance speed of the recording medium;
In the preliminary discharge determination timing, when the total of the non-operation time and the non-operation scheduled time exceeds the first reference time in the nozzle operated in the next image, the preliminary discharge of the nozzle is executed, For a nozzle that is not operated in the next image, the preliminary ejection of the nozzle is executed when the sum of the non-operating time and the time from the present to the end of printing the rear end of the next image exceeds the second reference time. A preliminary ejection process;
The preliminary discharge control method characterized by including.

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