JP2008049562A - Inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recorder which can perform a suitable preparatory discharge even when nozzles used for recording an image vary. <P>SOLUTION: When the using range of a discharge port is changed by a recording control means among scans, a preparatory discharge control means makes an ink droplet which does not contribute to an image recording discharged from the discharge port based on the number of an ink discharge for every discharge port included in the using range after determining the using range of the discharge port. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus. More specifically, the present invention relates to an ink jet recording apparatus that discharges ink droplets that do not contribute to image recording from nozzles of the recording head and performs recovery processing of the recording head.

  The ink jet recording apparatus records an image by ejecting ink in the nozzles as ink droplets toward a recording medium from an ejection port provided in the recording head. In this recording head, ink in the nozzles is reduced by the ejection of ink droplets, and new ink is filled into the nozzles from the ink liquid chamber by capillary force. If moisture or solvent in the ink evaporates from the ejection port of the recording head, there is a possibility that an ink ejection failure may occur due to thickening of the ink in the nozzle. Therefore, before the ejection failure occurs, ink droplets that do not contribute to image recording are ejected from the ejection port (hereinafter referred to as “preliminary ejection”) to prevent ejection failure due to thickening of the ink in the nozzle. The preliminary ejection is performed by moving the recording head to the outside of the recording medium and ejecting ink droplets at the moving position. By performing such preliminary ejection, it is possible to maintain a good ink ejection state in the recording head.

  As a control mode of the preliminary discharge, there is a mode in which the preliminary discharge is performed when a predetermined time or more has elapsed since the previous preliminary discharge. For example, in the case of a serial scan type ink jet recording apparatus, it is determined whether or not a predetermined time or more has elapsed since the previous preliminary ejection when reversing the reciprocation of the carriage on which the recording head is mounted. When the predetermined time or more has elapsed, the recording head is moved to the outside of the recording medium, and preliminary ejection is performed at the moving position. Hereinafter, such a control form is also referred to as “periodic control”.

  However, since such periodic control performs preliminary discharge every time a predetermined time or more has elapsed since the previous preliminary discharge, there is a possibility that preliminary discharge may be performed more than necessary. If the preliminary ejection is frequently performed, the recording speed (throughput) is lowered, and further, the consumption of ink leads to an increase in running cost.

  Japanese Patent Application Laid-Open No. 2004-151858 describes a mode of performing preliminary ejection according to the frequency of nozzle use as a mode of preliminary ejection control that eliminates such problems. In this control mode, it is determined for each nozzle whether or not the number of ink ejected from the nozzles of the recording head has reached a predetermined number during a predetermined time. Then, the printable time determined based on the determination result is compared with the time required for the next print scan, and when the printable time is shorter than the time required for the next print scan, preliminary ejection is performed. Thus, the preliminary ejection can be efficiently executed by counting (monitoring) the number of ejections of the ink droplets ejected from the respective nozzles. Hereinafter, such a control form is also referred to as “nozzle monitor control”.

JP 2005-238712 A

  By the way, in the ink jet recording apparatus, the conveyance amount at the time of recording and the nozzle (used nozzle) used for recording may be changed (shifted).

  For example, recording may be performed with both ends of the recording medium in the transport direction, that is, the front end and the rear end, being smaller than the normal transport amount. The reason is that the recording medium cannot be transported using both the transport roller and the paper discharge roller at both ends of the recording medium, so that the transport accuracy of the recording medium is lowered, and the influence of the decrease in the transport accuracy is suppressed. For this reason, both ends of the recording medium are made smaller than the normal transport amount. Thus, the amount of the recording medium transported is reduced, so that the nozzles used in the recording head are also limited, and an image is recorded on both ends of the recording medium using some nozzles of the recording head. .

  Further, during recording on both ends of the recording medium, the conveyance amount of the recording medium and the nozzles used for recording may be changed. For example, if the conveyance line that conveys the recording medium through the recording position facing the recording head includes a conveyance roller that is located upstream of the recording position, the trailing end of the recording medium comes out of the nip portion of the conveyance roller. Sometimes, the conveyance amount of the recording medium temporarily increases. As described above, the fact that the conveyance amount when the trailing edge of the recording medium moves away from the conveyance roller is larger than the predetermined conveyance amount is also referred to as “kicking”. At the time of recording on the rear end portion of the recording medium, the use nozzle is shifted in consideration of such a change in the conveyance amount due to kicking.

  With reference to FIG. 8, an example of control for shifting the nozzles used in consideration of kicking during the recording on the rear end of the recording medium in the serial scan type inkjet recording apparatus will be described.

  8A represents all nozzles (for example, 512 nozzles) in the recording head H, and a nozzle row is formed along the conveyance direction (sub-scanning direction) of the recording medium indicated by the arrow B. . L10 is the nozzle width (total nozzle width) of all nozzles. The ink jet recording apparatus alternately repeats a recording operation in which the recording head H ejects ink droplets from the nozzles while moving in the main scanning direction indicated by the arrow A and a conveying operation that conveys the recording medium in the sub-scanning direction indicated by the arrow B. Record an image. During recording on the central portion of the recording medium, the conveyance amount of the recording medium corresponds to the entire nozzle width L10, and the used nozzles NB are all nozzles. The used nozzle NB at the time of recording with respect to the rear end portion of the recording medium is a nozzle within the nozzle width L11 smaller than the entire nozzle width L10, and the conveyance amount of the recording medium corresponds to the nozzle width L11. In the case of this embodiment, the nozzle width L11 is half of the total nozzle width L10 (= 256 nozzles), and the used nozzle NB is positioned on the paper supply side, which is the lower side of the figure. Further, at the time of recording on the rear end portion of such a recording medium, the position of the use nozzle NB is once shifted as shown in FIG. 8C in accordance with the timing at which the kicking occurs, and then FIG. As described above, the position of the use nozzle NB is further shifted to the paper feed side.

  The nozzle monitor control described above can perform efficient preliminary ejection when the transport amount of the recording medium during recording is constant and the used nozzles used for recording in each recording scan are constant. However, as shown in FIG. 8, if the transport amount of the recording medium at the time of recording is not constant and the nozzles used for recording in each recording scan are not constant, appropriate preliminary ejection may not be executed.

  That is, the nozzle monitor control controls the execution of the preliminary discharge according to the use frequency of the used nozzles for each print scan. For this reason, the nozzle NX11 that has not been monitored in the recording scan of FIG. 8B becomes a used nozzle MB in the recording scan of FIG. 8C without being monitored. In some cases, the nozzle NX11 newly set as the use nozzle NB in the print scan of FIG. 8C has an abnormal ink ejection state. The same applies to the nozzle NX12 which is not subject to monitoring in the print scan of FIG. 8C and has become the nozzle used MB in the print scan of FIG. 8D.

  If the nozzles in the range of NB and NX11 in FIG. 8B are to be monitored and the execution of the preliminary discharge is controlled according to the frequency of use of the used nozzles, from FIG. In the printing scan of d), there are nozzles NX11 or NX12 that are not used. For this reason, in such a configuration, there is a possibility that a problem that the preliminary ejection is executed every recording scan may occur.

  As described above, in the conventional nozzle monitor control, when the used nozzle is changed, there is a possibility that appropriate preliminary discharge may not be performed such as necessary preliminary discharge not being performed or excessive preliminary discharge being performed. .

  Therefore, Patent Document 1 discloses an ink jet recording apparatus in which a preliminary ejection control mode is periodically controlled at a front end portion and a rear end portion of a recording medium in which a use nozzle changes. However, as described above, since the periodic control performs the preliminary discharge every time a predetermined time or more has passed since the previous preliminary discharge, there is a problem that the preliminary discharge is performed more than necessary and the recording speed (throughput) is reduced. End up.

  An object of the present invention is to provide an ink jet recording apparatus capable of performing appropriate preliminary discharge even when the nozzle used for image recording changes.

  The inkjet recording apparatus of the present invention uses an ejection port used for printing in each scanning in an inkjet recording apparatus that records an image on a recording medium by scanning a recording head having a plurality of ejection ports capable of ejecting ink droplets. Based on the recording control means for determining the range and executing the recording of each scan by the ejection ports included in the use range, and after the end of recording in each scan, based on the number of ink ejections for each ejection port included in the use range Preliminary ejection control means for ejecting ink droplets that do not contribute to image recording from the ejection openings, and when the use range of the ejection openings is changed between scans by the recording control means, the preliminary ejection control means After the use range of the discharge port is determined, ink droplets that do not contribute to image recording are discharged from the discharge port based on the number of ink discharges for each discharge port included in the use range. Characterized in that to.

  According to the ink jet recording apparatus of the present invention, even when the used nozzle changes, it is possible to perform appropriate preliminary discharge without performing necessary preliminary discharge or without performing unnecessary preliminary discharge. It becomes possible.

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

  In this specification, “recording” (sometimes referred to as “printing”) is not only for forming significant information such as characters and graphics, but also for images, A case where a pattern, a pattern, or the like is formed or a medium is processed is also expressed. The “recording medium” is not only paper used in general recording apparatuses, but widely includes cloth, plastic film, metal plate, glass, ceramics, wood, leather, etc., and can accept ink. It also represents things. Further, “ink” (sometimes referred to as “liquid”) should be interpreted widely as in the definition of “recording (printing)”. That is, the “ink” is applied to the recording medium, thereby forming an image, pattern, pattern, etc., processing the recording medium, or processing the ink (for example, the colorant in the ink applied to the recording medium). It represents a liquid to be subjected to a treatment for coagulation or insolubilization. In addition, “nozzle” (sometimes referred to as “recording element”) refers to an ejection port, a liquid path communicating with the ejection port, and an element that generates energy used for ejecting ink droplets unless otherwise specified. Say it.

(Mechanical configuration of inkjet recording apparatus)
FIG. 1 is an external perspective view of a main part for explaining the mechanical configuration of an ink jet recording apparatus to which the present invention is applicable.

  In an ink jet recording apparatus (also referred to as “recording apparatus”) 1 of this embodiment, a recording head 3 is detachably mounted on a carriage 2, and the carriage 2 is reciprocated in the main scanning direction indicated by an arrow A. The driving force of the carriage 2 is transmitted from the carriage motor M1 via the transmission mechanism 4. The transmission mechanism 4 according to the present embodiment includes a drive pulley driven by a carriage motor M1, a driven pulley, and a belt 7 spanned between the pulleys and connected to the carriage 2. . A recording medium P such as recording paper is fed through a paper feeding mechanism 5 and conveyed to a recording position, and an image is recorded by ink ejected from the recording head 3 at the recording position.

  Reference numeral 10 denotes a recovery device for maintaining a good ink discharge state of the recording head 3. The carriage 2 moves to the position of the recovery device 10, and the ink droplets that the recording head 3 does not contribute to image recording can be discharged (preliminary discharge) into the cap of the recovery device 10. The configuration of the recovery device 10 will be described later.

  An ink cartridge 6 that stores ink to be supplied to the recording head 3 is detachably mounted on the carriage 2. The ink cartridge 6 may constitute an ink jet cartridge together with the recording head 3. The ink jet recording apparatus 1 of this embodiment can record a color image. Therefore, four ink cartridges 6 that contain magenta (M), cyan (C), yellow (Y), and black (K) inks are mounted on the carriage 2. These four ink cartridges 6 are detachable independently.

  The carriage 2 and the recording head 3 are maintained in the required electrical connection between them when their joint surfaces are in proper contact. The recording head 3 can selectively eject ink from a plurality of ejection ports according to a recording signal. The recording head 3 according to the present embodiment employs an ink jet system that ejects ink droplets using thermal energy, and includes an electrothermal transducer (heater) to generate thermal energy. The electric energy applied to the electrothermal converter is converted into thermal energy, and the thermal energy is applied to the ink, whereby film boiling occurs in the ink. Then, bubble growth and contraction occur in the ink due to the film boiling, and ink droplets can be ejected from the ejection port by utilizing the accompanying ink pressure change. This electrothermal transducer is provided corresponding to each of the ejection ports, and when a pulse voltage is applied to the electrothermal transducer in accordance with the recording signal, ink droplets are ejected from the ejection port corresponding to the electrical transducer. Is done. The recording head 3 may be a system that ejects ink droplets using a piezo element or the like.

  The carriage 2 is reciprocated in the main scanning direction indicated by the arrow A along the guide shaft 13 by forward and reverse rotations of the carriage motor M1. A scale 8 for indicating the absolute position of the carriage 2 is provided along the moving direction of the carriage 2. The scale 8 of this embodiment is a transparent PET film on which black bars are printed at a constant pitch, one of which is fixed to the chassis 9 and the other is supported by a leaf spring (not shown). .

  The ink jet recording apparatus 1 is provided with a platen 23 (see FIGS. 3 and 4) at a position facing the discharge port surface of the recording head 3 on which the discharge ports are formed. By ejecting ink droplets from the recording head 3 based on the recording signal while the recording head 3 reciprocates together with the carriage 2, an image is formed over the entire width of the recording medium P conveyed on the platen 23. Record.

  A conveyance roller 14 conveys the recording medium P in the sub-scanning direction indicated by the arrow B, and is driven by a conveyance motor M2. Reference numeral 15 denotes a pinch roller that abuts the recording medium P against the conveying roller 14 by an urging force of a spring (not shown), and reference numeral 16 denotes a pinch roller holder that rotatably supports the pinch roller 15. Reference numeral 17 denotes a conveyance roller gear fixed to one end of the conveyance roller 14. The conveyance roller 14 is driven by the rotation of the conveyance motor M2 being transmitted to the conveyance roller gear 17 via an intermediate gear (not shown).

  A discharge roller 20 discharges the recording medium P on which an image has been recorded by the recording head 3 to the outside of the inkjet recording apparatus 1. The discharge roller 20 is driven by the rotation of the transport motor M2. A spur roller 21 (see FIGS. 3 and 4) presses the recording medium P against the discharge roller 20 by a spring (not shown). Reference numeral 22 denotes a spur holder that rotatably supports the spur roller 21.

  The recovery device 10 described above includes a capping mechanism 11 for capping the ejection port surface of the recording head 3 with a cap, and a wiping mechanism 12 for cleaning the ejection port surface of the recording head 3. In conjunction with the capping of the discharge port surface by the cap of the capping mechanism 11, negative pressure is introduced into the cap by the suction means (suction pump or the like) of the recovery device 10, so that the discharge port of the recording head 3 enters the cap. Force ink to be sucked out. As a result, it is possible to remove the thickened ink, bubbles, and the like in the nozzles of the recording head 3 and the ink flow path, and to maintain the ink ejection state well.

  Further, by capping the ejection port surface with the cap of the capping mechanism 11 during a non-recording operation or the like, the recording head 3 can be protected and ink evaporation from the ejection port and drying can be prevented. In addition, the wiping mechanism 12 is provided in the vicinity of the capping mechanism 11 and wipes ink droplets attached to the ejection port surface of the recording head 3.

  The capping mechanism 11 and the wiping mechanism 12 enable a recovery process to keep the ink ejection state of the recording head 3 normal. The recovery process includes the preliminary ejection described above.

(Configuration of control system of ink jet recording apparatus)
FIG. 2 is a block configuration diagram of a control system of the inkjet recording apparatus 1.

  In FIG. 2, the controller 600 includes an MPU 601, a ROM 602, a special purpose integrated circuit (ASIC) 603, a RAM 604, a system bus 605, and an A / D converter 606. The ROM 602 stores a program corresponding to a control sequence to be described later, a required table, and other fixed data. The ASIC 603 generates a control signal for the carriage motor M 1, a conveyance motor M 2, and a recording head 3. The RAM 604 is provided with an image data development area, a work area for program execution, and the like. A system bus 605 connects the MPU 601, the ASIC 603, and the RAM 604 to each other to exchange data. The A / D converter 606 performs A / D conversion on analog signals input from a sensor group 630 described later, and supplies the converted digital signal to the MPU 601. The controller 600 executes recovery processing by nozzle monitor control, as will be described later, in accordance with a program stored in the ROM 602.

  Reference numeral 610 denotes a host device serving as a supply source of image data, which includes a computer, a reader for image reading, a digital camera, and the like. The host apparatus 610 and the inkjet recording apparatus 1 transmit and receive image data, commands, status signals, and the like via an interface (I / F) 611.

  A switch group 620 includes a power switch 621, a print switch 622, a recovery switch 623, and the like. The print switch 622 is a switch for instructing the start of printing, and the recovery switch 623 is for instructing to start the above-described recovery processing, that is, processing for maintaining the ink ejection performance of the recording head 3 in a good state. Switch. Further, the switch group 620 includes a switch for receiving a command input from the operator.

  Reference numeral 620 denotes a sensor group including sensors for detecting the state of the inkjet recording apparatus 1 such as a position sensor 631 and a temperature sensor 632. The position sensor 631 is a sensor for detecting that the carriage 2 has moved to a predetermined home position so that the recording head 3 faces the recovery device 10, and is constituted by a photocoupler or the like. The temperature sensor 632 is a sensor provided at an appropriate location of the inkjet recording apparatus 1 in order to detect the environmental temperature.

  Reference numeral 640 denotes a carriage motor driver which drives and controls a carriage motor M1 for reciprocally scanning the carriage 2 in the main scanning direction indicated by an arrow A. Reference numeral 642 denotes a conveyance motor driver, which drives and controls a conveyance motor M2 for conveying the recording medium P in the sub-scanning direction indicated by the arrow B. The ASIC 603 transfers drive data (DATA) of the electrothermal transducer (recording element) to the recording head 3 while directly accessing the storage area of the RAM 604 during recording scanning by the recording head 3.

  The inkjet recording apparatus 1 having such a configuration stores image data transferred from the host apparatus 610 via the interface 611 in the RAM 604, generates recording data indicating ink ejection information from the image data, and stores the image data in the RAM 604. Store. At the time of recording, an image is recorded on the recording medium P by ejecting ink from each ejection port of the recording head 3 based on the recording data. That is, an image is sequentially recorded on the recording medium P by repeating the operation of ejecting ink droplets while the recording head 3 moves in the main scanning direction and the operation of transporting the recording medium P in the sub-scanning direction.

(Recording operation to the edge of the recording medium)
3 and 4 are explanatory diagrams of the relationship between the conveyance amount of the recording medium P and the used nozzles of the recording head 3, and these are when recording on the rear end portion of the recording medium P and when recording on the central portion. Is different. FIG. 5 is an explanatory diagram of changes in the nozzles used and nozzles to be monitored.

  The recording medium P is transported on the transport line (transport path) L in the sub-scanning direction indicated by the arrow B by the transport roller 14 and the paper discharge roller 20. At the time of image recording, the recording operation in which the recording head 3 ejects ink droplets from the nozzles while moving in the main scanning direction indicated by the arrow A and the conveying operation for conveying the recording medium in the sub-scanning direction indicated by the arrow B are alternately repeated. As will be described later, the ink jet recording apparatus 1 of the present embodiment can perform borderless recording with no margin on the rear end of the recording medium P, and is provided with an ink absorber 24 for this purpose. During borderless recording, ink droplets ejected from the nozzles of the recording head 3 located on the upstream side in the conveyance direction of the recording medium P and removed from the recording medium P are received by the ink absorber 24.

  5A represents all the nozzles (for example, 512 nozzles) in the recording head 3, and forms a nozzle row along the recording medium conveyance direction (sub-scanning direction) indicated by the arrow B. In FIG. At the time of recording on the central portion of the recording medium P, as shown in FIG. 3A, all nozzles within the entire nozzle width L0 of the recording head 3 are used nozzles NA, and the conveyance amount F of the recording medium P is the total nozzle width. Corresponds to L0.

  As shown in FIG. 3C, after the recording medium P is removed from the transport roller 14, the transport operation is performed only by the paper discharge roller 20, and therefore the transport accuracy of the recording medium P is lowered. In order to suppress the influence of such conveyance accuracy, the conveyance amount F of the recording medium P is reduced from the conveyance operation before the trailing end Pe of the recording medium P is detached from the conveyance roller 14 as shown in FIG. . In the case of this embodiment, the transport amount F of the recording medium P at that time corresponds to a nozzle width L1 that is ¼ of the total nozzle width L0, and the used nozzle NA at that time is on the upstream side in the transport direction of the recording medium P. The nozzle is within the nozzle width L1 positioned (see FIG. 5B).

  As shown in FIG. 3C, when the trailing edge Pe of the recording medium P is detached from the conveying roller 14 and the conveying operation of the recording medium P shifts to the conveying operation using only the paper discharge roller 20, the conveying of the recording medium P is performed. There is a tendency that the amount becomes temporarily large and the conveyance accuracy decreases. This is because the transport roller 14 cannot firmly grip the rear end Pe of the recording medium P in a state where the rear end Pe of the recording medium P is far from the transport roller 14. Thus, the quality of the recorded image is lowered due to the decrease in the conveyance accuracy. The phenomenon that the conveyance amount of the recording medium P temporarily increases when the rear end Pe of the recording medium P moves away from the conveyance roller 14 is referred to as “kicking” as described above. The recording area before kicking occurs is called “kicking preparation area”.

  In this embodiment, the state where the kicking and the rear end Pe of the recording medium P are separated from the transport roller 14 is included in one transport operation so that the transport accuracy does not deteriorate. Specifically, as shown in FIGS. 3C and 5C, the conveyance amount of the recording medium P is prevented so that the trailing edge Pe of the recording medium P does not stop at the last minute state when the recording medium P leaves the conveyance roller 14. F is increased, and at the same time, the position of the used nozzle NA is shifted. A series of operations for switching the position of the used nozzle NA used for recording by temporarily increasing the conveyance amount F of the recording medium P during recording on the rear end of the recording medium P is referred to as “kicking processing”. Is done.

  In the kick preparation area, as a pre-stage for performing the kicking process, as shown in FIGS. 3B and 5B described above, a part of all the nozzles on the paper feeding side (upstream side in the transport direction) The used nozzle NA is switched so as to be the used nozzle NA. Until the kicking process is performed, recording is performed using some limited use nozzles NA on the paper feeding side. In other words, in the kick preparation area, the recording is performed from the normal recording area of the recording medium P by the used nozzle NA in FIG. 5A to the recording state by the used nozzle NA on the paper feeding side in FIG. Transition. Thus, when the used nozzle NA is switched from FIG. 5A to FIG. 5B, the number of used nozzles may be gradually reduced.

  In the kicking process of this embodiment, as shown in FIGS. 3C and 5C, the conveyance amount F of the recording medium P is set to twice the nozzle width L1, and at the same time, the position of the used nozzle NA is set to the nozzle width L1. Only shifts to the paper discharge side (downstream in the transport direction). When all the nozzles of the recording head 3 are 512 nozzles and the nozzle width L1 is 1/4 of the total nozzle width L0, the carry amount F is from 128 nozzles (nozzle width L1) to 256 nozzles (nozzles in the kick preparation area). Twice the width L1). At that time, an increase in the conveyance amount of the recording medium P due to kicking is considered. For example, when it can be expected that the increase in the conveyance amount of the recording medium P due to kicking is equivalent to two nozzles, the conveyance amount of the recording medium P by the paper feed roller 14 and the paper discharge roller 20 is set to 254 (= 256-2). ) Nozzle. As a result, the recording medium P is transported for 256 nozzles as expected.

  After the use nozzle NA is shifted to the paper discharge side as shown in FIGS. 3C and 5C by such kicking processing, as shown in FIGS. 4B and 5D, The used nozzle NA is gradually shifted to the paper feeding side. Finally, as shown in FIGS. 5B and 5E, the used nozzle NA is returned to the position on the paper feeding side. In this way, with the process of shifting the used nozzle NA stepwise to the paper feed side (also referred to as “shift process” or “nozzle return process”), the transport amount F of the recording medium P decreases stepwise, and finally Accordingly, the amount corresponds to the nozzle width L1 as shown in FIGS. 4B and 5E.

  At the time of recording scanning with respect to the rearmost end portion of the recording medium P, as shown in FIG. 4C, the rear end Pn of the recording medium P deviates from the position facing the nozzles in the sheet feeding side range S of the use nozzle NA. Ink droplets that have been ejected from the nozzles in the paper feed side range S and have not landed on the recording medium P are absorbed by the absorber 24. In this manner, borderless recording without margins can be performed on the rear end portion of the recording medium P.

  As described above, in this embodiment, after the use nozzle NA is completely shifted to the paper feeding side as shown in FIGS. 4B and 5E, an image is recorded by a plurality of scans, and the recording medium is recorded. Borderless recording is performed on the rear end of P as described above. Depending on the deployment position of the absorber 24, as shown in FIG. 5C or FIG. 5D, there is no edge with respect to the rear end portion of the recording medium P by the use nozzle NA that is not completely shifted to the paper feeding side. Recording can also be performed. For example, when borderless recording is performed on the rear end portion of the recording medium P by the use nozzle NA in FIG. 5C, the absorber 24 is provided at a position facing the use nozzle NA. Become. In this case, a shift process (nozzle return process) for shifting the position of the used nozzle NA to the paper feed side is not necessarily required. Further, such a shift process becomes unnecessary when no borderless recording is performed on the rear end portion of the recording medium P.

(Control mode of recovery processing)
In this embodiment, the execution of the preliminary discharge is controlled by nozzle monitor control. As described above, in this nozzle monitor control, it is determined for each nozzle whether or not the number of ink droplets ejected from the nozzles of the recording head has reached a predetermined number during a predetermined time. Then, the printable time determined based on the determination result is compared with the time required for the next print scan, and when the printable time is shorter than the time required for the next print scan, preliminary ejection is performed. Thus, the preliminary ejection can be efficiently executed by counting (monitoring) the number of ejections of the ink droplets ejected from the respective nozzles.

  As shown in FIG. 5A, during the recording operation in which all nozzles are used nozzles NA, all the nozzles become nozzles to be monitored. On the other hand, when the use nozzle NA changes as shown in FIG. 5B to FIG. 5E, all nozzles are monitored until the change (shift) of the use nozzle NA is finished as shown in FIG. Nozzle monitor control is performed as an object. Then, as shown in FIG. 5E, after the change of the used nozzle NA is completed and confirmed, nozzle monitor control is performed with the used nozzle NA as a monitoring target, and nozzles other than the used nozzle NA are obtained. Is removed from the monitoring target. The determined use nozzle is referred to as “determined use nozzle”.

  In this manner, until all the used nozzles NA are determined, all the nozzles are to be monitored. Naturally, in the printing scan of FIG. 5B, not the used nozzle MA but the printing scan of FIG. 8C. The nozzle NX1 that has become the used nozzle MA is also subject to monitoring. The same applies to the nozzle NX2 that has become the use nozzle MA in the print scan of FIG. 8D, not the use nozzle MA in the print scan of FIG. 5C. The same applies to the nozzle NX3 that has become the use nozzle MA in the print scan of FIG. 8 (e), not the use nozzle MA in the print scan of FIG. 5 (d). Accordingly, until the nozzles NA to be used are determined, the nozzle monitor control for monitoring all the nozzles including these nozzles NX1, NX2, and NX3 is performed, and the ink discharge state is favorably maintained for all the nozzles. Can do.

  On the other hand, after the used nozzle NA is determined, by performing nozzle monitor control that excludes nozzles other than the used nozzle NA from monitoring targets, unnecessary ink consumption is suppressed without performing preliminary discharge more than necessary. Throughput can be improved.

  Further, until the used nozzle NA is determined, the number of nozzles that are not used until the last recording scan of the recording medium P increases like the nozzles NY1 and NY2 in FIGS. 5C and 5D. Such nozzles NY1 and NY2 are desirably excluded from monitoring targets for nozzle monitor control.

  Further, after the use nozzle NA is determined, if there is no effect on the image recording on the recording medium P of the next page, the preliminary discharge may be performed only from the determined use nozzle NA. After the use nozzles are determined, it is not always necessary to perform preliminary ejection for all the nozzles, and thereby wasteful consumption of ink can be suppressed.

  As a method for determining that the used nozzle has been determined, there is a method in which the RAM 604 manages the number of nozzles from the paper feed side of the recording head 3 to the used nozzle that changes in accordance with the kicking process and the nozzle returning process. . In the above-described example, first, by using the kicking process, as shown in FIG. 5C, the used nozzle NA is at a position where 128 nozzles are opened from the paper feeding side, so 128 is set in the RAM 604 as a set value. Next, as shown in FIG. 5D, when the used nozzle NA is shifted by the nozzle return process, the setting value of the RAM 604 is changed for each printing scan as 128, 96, 64, and 32. Go. Then, at the stage where the set value becomes 0 and the used nozzle is completely on the sheet feeding side as shown in FIG.

  After the used nozzle is determined, the recovery process by the nozzle monitor control is executed by the controller 600 in accordance with a program stored in the ROM 602.

  First, the printable time (PENBL) is initialized to a predetermined value, and the measurement value (Dcount (i) i = 1, N) of the nozzle counter that measures the number of ejection driving times for each nozzle of the recording head 3 is initialized to be all. The measured value is “0”. Furthermore, in the next step, an interrupt timer for starting timing for updating the recordable time (PENBL) at predetermined time intervals is started. For example, in this embodiment, the interrupt time interval (TINRT) is 50 milliseconds. N is the number of nozzles, and the recordable time (PENBL) is a time during which normal ink ejection from the recording head 3 is expected, and is a value determined according to the performance of the recording head 3 and the inkjet recording apparatus 1. is there.

  Here, interrupt processing at intervals of 50 milliseconds will be described. First, as a first step, it is checked whether all the measured values (Dcount (i) i = 1, N) of the nozzle counter have reached a predetermined value (TH). In this embodiment, TH = 3. Here, for all measured values of the nozzle counter, if Dcount ≧ 3, the recordable time (PENBL) is reset and initialized. On the other hand, regarding the measured value of any nozzle counter, if Dcount <3, the value obtained by subtracting 50 milliseconds from the recordable time (PENBL) is updated as the new recordable time (PENBL). After any processing, all the measurement values (Dcount (i) i = 1, N) of the nozzle counter are initialized and all the measurement values are set to “0”. The above processing is interrupt processing at intervals of 50 milliseconds.

  During recording, control is performed to reduce the moving speed of the recording head 3 between recording scans, then reverse the moving direction, and accelerate for the next recording scan. Before one recording scan is completed and the control shifts to decelerating the moving speed of the recording head 3, whether or not the recording is completed is checked. If it is determined that the recording is not completed, the recordable time (PENBL at that time) is determined. ) And the time (Tscan) required for the next recording scan. If PENBL <Tscan, it is determined that preliminary ejection is necessary, the recording head 3 is moved to the preliminary ejection position, preliminary ejection is performed, and the process proceeds to Step A. If PENBL ≧ Tscan, it is determined that preliminary ejection is not necessary, and the process proceeds to step A as it is.

  In step A, the recordable time (PENBL) is initialized, and the measurement values (Dcount (i) i = 1, N) of the nozzle counter are initialized to set all measurement values to “0”. Thereafter, the recording scan is resumed. Preliminary discharge by nozzle monitor control is performed by a series of processes as described above. The preliminary discharge by the nozzle monitor control as described above is not limited to the case where the used nozzles after the used nozzles are determined are set as monitoring targets, but the same applies to the preliminary discharge in which all the nozzles are monitored.

  FIG. 6 is a flowchart for explaining a series of control procedures for preliminary discharge by nozzle monitor control.

  In this embodiment, the change of the used nozzle NA is started by the kicking process, and the shift process (nozzle return process) is performed when the marginless recording is performed, and the shift process (nozzle return process) is performed when the marginless recording is not performed. ) Shall not be performed. Before the use nozzles NA are determined, all nozzles are set as target nozzles for preliminary discharge, and after the use nozzles NA are set, only the use nozzles NA are set as target nozzles for preliminary discharge.

  First, in step S1, it is determined whether or not a kicking process has been performed. When the kicking process is not performed, the process proceeds to step S4, where the nozzles to be monitored are set as all nozzles, and in step S5, nozzle monitor control is performed with all the nozzles being the target nozzles for preliminary ejection.

  When the kicking process is performed, the process proceeds from step S1 to step S2, and it is determined whether or not the borderless recording mode for performing borderless recording is set as the recording mode. When the borderless recording mode is not set, the used nozzle NA (used nozzle NA in FIG. 5C) after the kicking process is determined as the nozzle used until the last recording scan of the recording medium P. In this case, the process proceeds to step S6, and the determined used nozzle NA is set as a monitoring target nozzle. In step S5, nozzle monitor control is performed with the used nozzle NA as a target nozzle for preliminary ejection.

  When the borderless recording mode is set, the process proceeds from step S2 to step S3, and it is determined whether or not the shift process is completed. When the shift process is completed, the used nozzle NA (used nozzle NA in FIG. 5E) after the completion of the shift process is determined as the nozzle used until the last print scan of the print medium P. In this case, the process proceeds to step S6, and the determined used nozzle NA is set as a monitoring target nozzle. In step S7, nozzle monitor control is performed with the used nozzle NA as a target nozzle for preliminary ejection.

  If the shift process has not been completed, it is determined that the used nozzle NA has not been determined, and the process proceeds to step S4, where the nozzles to be monitored are set to all nozzles, and in step S5, all the nozzles are to be subjected to preliminary ejection. Perform nozzle monitor control.

(Other examples of control mode of recovery processing)
In the above description, the preliminary discharge control for the central portion of the recording medium P is the nozzle monitor control. However, the preliminary discharge control until the use nozzle is determined is performed by the periodic control, and after the use nozzle is determined, the nozzle monitor control is changed. It doesn't matter.

  The recording head may be provided with a plurality of types of nozzles having different ejection amounts of ink droplets, and in this case, a preliminary ejection control mode corresponding to each type of nozzle can be employed.

  For example, when the recording head includes a large-diameter large nozzle capable of ejecting relatively large ink droplets and a small-diameter small nozzle capable of ejecting relatively small ink droplets, as shown in FIG. A pre-discharge control mode suitable for each nozzle can be employed. That is, for large nozzles, the cycle control is adopted at the time of recording at both the central portion and the rear end portion of the recording medium P. On the other hand, the same nozzle monitor control as that of the above-described embodiment is adopted for the small nozzles. That is, all the nozzles are subject to monitoring when recording at the central portion of the recording medium P, and all nozzles are subject to monitoring before the use nozzles are determined when recording at the rear end of the recording medium, and after the use nozzles are determined. The nozzles used are monitored.

  When preliminary discharge is performed from a large nozzle, preliminary discharge may be performed from a small nozzle in conjunction with this. In general, since a small nozzle is more likely to cause ejection failure due to thickening of ink in the nozzle than a large nozzle, it is preferable to perform preliminary ejection from a small nozzle when performing preliminary ejection from a large nozzle.

(Other embodiments)
When recording on the front end portion of the recording medium, it is possible to perform borderless recording on the front end portion of the recording medium by changing the conveyance amount of the recording medium and the nozzle used in the recording head. In this case, during the period from the recording at the front end of the recording medium to the recording at the center, the number of used nozzles changes gradually, and finally, the used nozzles are determined as all nozzles. Become. When nozzle monitor control is employed as a preliminary ejection control mode at the time of recording at the front end of the recording medium, the monitoring target may be all nozzles.

  The recording head may be provided with large nozzles, medium nozzles, and small nozzles, or may be provided with nozzles of different configurations, and a preliminary ejection control mode suitable for each type of nozzle. Can be adopted. As one of the control forms, the nozzle monitor control of the above-described embodiment can be employed.

  Further, in the nozzle monitor control of the above-described embodiment, all the nozzles are set as monitoring targets before the use nozzles are determined, and after the use nozzles are determined, the determined use nozzles are set as monitoring targets. However, when it is determined after the used nozzle has changed in multiple stages, the used nozzle in the stage before the used nozzle is completely determined may be treated as the determined used nozzle.

  Further, the nozzle monitor control as described above can also be adopted when the nozzles to be used are changed at times other than the time of recording on the rear end portion of the recording medium.

  Further, the host device 610 (see FIG. 2) may have some or all of the above-described nozzle monitor control functions.

1 is an external perspective view of a main part of an ink jet recording apparatus as an embodiment of the present invention. FIG. 2 is a block configuration diagram of a control system in the ink jet recording apparatus of FIG. 1. (A) to (c) are explanatory views of the recording operation in the ink jet recording apparatus of FIG. (A) to (c) are explanatory views of the recording operation in the ink jet recording apparatus of FIG. (A) to (e) are explanatory diagrams of the relationship between the recovery process and the used nozzles in the ink jet recording apparatus of FIG. 2 is a flowchart for explaining nozzle monitor control in the ink jet recording apparatus of FIG. 1. It is explanatory drawing of the other example of the recovery process in the inkjet recording device of FIG. (A) to (d) are explanatory views of the relationship between the recovery process and the used nozzles in the conventional ink jet recording apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 2 Carriage 3 Recording head 10 Recovery device 14 Paper feed roller 20 Paper discharge roller 600 Controller 601 MPU
602 ROM
603 ASIC
604 RAM
605 System bus 605 A / D converter 610 Host device 611 Interface P Recording medium Pe Rear end L Conveyance line (conveyance path)

Claims (8)

In an inkjet recording apparatus that scans a recording head having a plurality of ejection openings capable of ejecting ink droplets and records an image on a recording medium,
Means for determining the use range of the discharge ports used for printing of each scan and executing printing of each scan by the discharge ports included in the use range, and changing the use range of the discharge ports between preceding scans And a recording control means for performing recording while fixing the use range of the ejection port between subsequent scans;
A first preliminary ejection operation for ejecting ink droplets that do not contribute to image recording after the end of recording in each scan based on the number of ink ejections for each ejection port for all ejection ports of the recording head; and Preliminary ejection capable of performing a second preliminary ejection operation for ejecting ink droplets that do not contribute to image recording from the ejection ports after the end of recording in each scan based on the number of ink ejections for each ejection port included in the use range Control means;
Have
The preliminary discharge control means performs the first preliminary discharge operation before fixing the use range of the discharge port, and executes the second preliminary discharge operation after fixing the use range of the discharge port. An ink jet recording apparatus. In an inkjet recording apparatus that scans a recording head having a plurality of ejection openings capable of ejecting ink droplets and records an image on a recording medium,
Means for determining the use range of the discharge ports used for printing of each scan and executing printing of each scan by the discharge ports included in the use range, and changing the use range of the discharge ports between preceding scans And a recording control means for performing recording while fixing the use range of the ejection port between subsequent scans;
A first preliminary ejection operation for ejecting ink droplets that do not contribute to image recording after the end of recording in each scanning according to a specified period from the ejection ports, and ink ejection for each ejection port included in the use range Based on the number, preliminary ejection control means capable of executing a second preliminary ejection operation for ejecting ink droplets that do not contribute to image recording after the end of recording in each scan from the ejection port;
Have
The preliminary discharge control means performs the first preliminary discharge operation before fixing the use range of the discharge port, and executes the second preliminary discharge operation after fixing the use range of the discharge port. An ink jet recording apparatus. Conveying means for conveying the recording medium by a first roller provided upstream in the conveying direction of the recording medium with respect to the recording position facing the recording head and a second roller provided downstream in the conveying direction from the recording position. Have
3. The ink jet recording apparatus according to claim 1, wherein the recording control unit changes a use range of the ejection port from a scan before a rear end of the recording medium is detached from the first roller.   The ink jet recording apparatus according to claim 3, wherein the transport unit changes a transport amount of the recording medium in accordance with a change in a use range of the discharge port.   When recording an image on a rear end portion of the recording medium, the recording control unit does not change the usage range of the ejection port until the last scan with respect to the recording medium after fixing the usage range of the ejection port. An ink jet recording apparatus according to any one of claims 1 to 4. A recording head provided with a plurality of first ejection ports capable of ejecting first ink droplets and a plurality of second ejection ports capable of ejecting second ink droplets having a volume larger than that of the first ink droplets is scanned. In an inkjet recording apparatus that records an image on a recording medium,
Means for determining the use range of the first discharge port and the second discharge port used for printing of each scan and executing printing of each scan by the first discharge port and the second discharge port included in the use range The usage range of the first ejection port and the second ejection port is changed between preceding scans, and the usage range of the first ejection port and the second ejection port is fixed between subsequent scannings. Recording control means for executing recording,
Based on the number of ink discharges for each of the first discharge ports of the recording head, ink droplets that do not contribute to image recording are discharged from the first discharge ports after the end of recording in each scan. Based on the first preliminary ejection operation and the number of ink ejections for each first ejection port included in the use range, ink droplets that do not contribute to image recording after the end of recording in each scan are discharged from the first ejection port. A preliminary ejection control means capable of executing a second preliminary ejection operation to be ejected and a third preliminary ejection operation for ejecting ink droplets that do not contribute to image recording from the second ejection port in accordance with a specified period;
Have
The preliminary discharge control means executes the first preliminary discharge operation before fixing the use ranges of the first discharge port and the second discharge port, and sets the first discharge port and the second discharge port. An ink jet recording apparatus that performs the second preliminary ejection operation after fixing a use range. A recording head provided with a plurality of first ejection ports capable of ejecting first ink droplets and a plurality of second ejection ports capable of ejecting second ink droplets having a volume larger than that of the first ink droplets is scanned. In an inkjet recording apparatus that records an image on a recording medium,
Means for determining the use range of the first discharge port and the second discharge port used for printing of each scan and executing printing of each scan by the first discharge port and the second discharge port included in the use range The usage range of the first ejection port and the second ejection port is changed between preceding scans, and the usage range of the first ejection port and the second ejection port is fixed between subsequent scannings. Recording control means for executing recording,
Based on a first preliminary ejection operation for ejecting ink droplets that do not contribute to image recording from the first ejection port according to a specified period, the number of ink ejections for each first ejection port included in the use range, The second preliminary ejection operation for ejecting ink droplets that do not contribute to image recording from the first ejection port after the end of recording in each scan, and the ink droplets that do not contribute to image recording according to a specified period Preliminary discharge control means capable of executing a third preliminary discharge operation for discharging from the second discharge port;
Have
The preliminary discharge control means executes the first preliminary discharge operation before fixing the use ranges of the first discharge port and the second discharge port, and sets the first discharge port and the second discharge port. An ink jet recording apparatus that performs the second preliminary ejection operation after fixing a use range. The said preliminary discharge control means performs the first preliminary discharge operation stage and the second preliminary discharge operation in conjunction with the third preliminary discharge operation. Inkjet recording apparatus.

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