JP2010064479A - Inkjet printer, and driving method for inkjet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet printer by which colors having been used for an image formation can be known, and at the same time, the discharging state of each nozzle and the carrying state of a medium can be checked. <P>SOLUTION: This inkjet printer includes a plurality of inkjet heads which form an image in an image forming region on the medium by discharging inks while reciprocating conforming to an input driving signal. The plurality of inkjet heads discharge inks of colors which are different from each other, and includes: a use color discriminating section for discriminating ink colors which are used and ink colors which are not used in the image formation to the image forming region; and a control section which makes the inkjet heads perform a first preliminary discharge wherein inks of colors to be used for the image formation and inks of colors not to be used for the image formation are respectively discharged to specified positions to a first preliminary discharging region on the medium according to the discriminating result by the use color discriminating section. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an inkjet printer that performs preliminary ejection in addition to ink ejection for image formation, and an inkjet printer driving method.

  Ink jet printers have a problem that nozzles that have not ejected ink for a long time are likely to be clogged or have poor ejection due to ink viscosity increase or solidification. In order to cope with this, an ink jet printer in which preliminary ejection for ejecting ink to an ink receiver arranged outside the image forming area at a timing other than image formation has been put into practical use.

  In the ink jet recording apparatus described in Japanese Patent Application Laid-Open No. 7-314708 of Patent Document 1, in order to perform preliminary discharge more effectively, a discharge nozzle having a small discharge opportunity is selected to perform preliminary discharge of ink to a specific portion of the medium. It is done.

JP 7-314708 A

  However, in the ink jet recording apparatus described in Patent Document 1 or the conventional ink jet printer, by performing preliminary ejection, it is possible to give ejection opportunities to nozzles that are not used for image formation. Since only ink is ejected onto an area other than the medium, the state of each nozzle cannot be confirmed.

  In the case of an ink jet printer having a plurality of color heads, a color head that is involved in image formation may be subjected to preliminary ejection as in Patent Document 1, but all nozzles are not involved in image formation. For this head, it is considered that preliminary ejection is not performed as a whole head. Since such a head does not eject ink for a long time, there is a risk that the ink viscosity increases and ejection failure occurs.

  In addition, when there is a defect in the formed image, it is difficult to determine which color and which position of the nozzle are defective in discharge from the mixed color image. Further, when there is also a medium conveyance failure, it becomes even more difficult to discriminate between a conveyance failure and a discharge failure and specify a nozzle with a discharge failure.

  SUMMARY An advantage of some aspects of the invention is that it provides an ink jet printer capable of knowing colors used for image formation. Furthermore, the objective of this invention is providing the inkjet printer which can confirm the discharge state of each nozzle. Another object of the present invention is to provide an ink jet printer capable of confirming a conveyance state of a medium.

  In order to solve the above problems, in the ink jet printer of the present invention, a plurality of ink jet heads that form an image in an image forming area on a medium by ejecting ink while reciprocating in accordance with an input drive signal. The plurality of inkjet heads discharge different colors of ink, and use color discriminating units for discriminating between ink colors used for image formation in the image forming area and ink colors not used, and discrimination by the use color discriminating unit Based on the result, the first preliminary ejection for ejecting the color ink used for image formation and the color ink not used for image formation to predetermined positions on the first preliminary ejection area on the medium is applied to the inkjet head. And a control unit to be performed.

  In the inkjet printer of the present invention, it is preferable that the control unit rearranges the predetermined positions of the respective colors in a predetermined order based on the determination result by the use color determination unit.

  The predetermined order in the first preliminary discharge of the ink jet printer of the present invention is preferably the order of ink of all colors not used for image formation first and then ink of all colors used for image formation.

  In the ink jet printer of the present invention, the first preliminary ejection is performed so that the ink ejected from the nozzles of each color has a certain width in the width direction of the medium and has a stripe shape extending in the conveyance direction of the medium. Is preferred.

  In the ink jet printer of the present invention, the first preliminary discharge is preferably performed for all nozzles of all colors.

  In the ink jet printer of the present invention, it is preferable that the first preliminary ejection region is on the downstream side of the image forming region in the forward direction in which the ink jet head moves.

  In the ink jet printer of the present invention, the control unit performs, on the ink jet head, the second preliminary discharge for discharging ink from all nozzles of all colors to the second preliminary discharge area on the medium, separately from the first preliminary discharge. Therefore, it is preferable that the second preliminary ejection is performed in a pattern in which the ink ejected from all the nozzles does not overlap each other.

  In the ink jet printer of the present invention, the ink jet head is divided into a predetermined number of blocks corresponding to the image density in the medium conveyance direction, and each ink jet is ejected in order from each block each time the ink jet head is reciprocated. An image unit is formed, and the second preliminary ejection is preferably performed by ejecting ink for each image unit for each nozzle.

  In the ink jet printer of the present invention, it is preferable that the second preliminary discharge area is downstream of the first preliminary discharge area in the forward direction in which the ink jet head moves.

  In the ink jet printer of the present invention, the control unit causes the third preliminary ejection region on the medium to eject ink from at least one nozzle at an interval corresponding to the transport amount of the medium separately from the first preliminary ejection. It is preferable to cause the inkjet head to perform the third preliminary discharge.

  In the ink jet printer of the present invention, it is preferable that the third preliminary discharge is performed every time the ink jet head is moved on the medium.

  In the ink jet printer of the present invention, the ink jet head is divided into a predetermined number of blocks corresponding to the image density in the medium conveyance direction, and each ink jet is ejected in order from each block each time the ink jet head is reciprocated. The image unit is formed, and the third preliminary ejection is preferably performed by ejecting ink for each image unit with respect to a predetermined nozzle.

  In the ink jet printer of the present invention, it is preferable that the third preliminary discharge region is downstream of the second preliminary discharge region in the forward direction in which the ink jet head moves.

  In the inkjet printer according to the aspect of the invention, it is preferable that the control unit causes the inkjet head to perform the fourth preliminary ejection for ejecting ink from all nozzles of all colors to the region outside the medium.

  The inkjet printer driving method of the present invention includes a plurality of inkjet heads that form an image in an image forming area on a medium by ejecting ink while reciprocating in accordance with an input drive signal. Inkjet printer driving method in which the inkjet heads discharge different colors of ink, and based on the drive signal, the used color discrimination that discriminates between the ink color used and the unused ink color in the image forming area Based on the determination result of the step and the used color determination unit, the ink of the color used for image formation and the ink of the color not used for image formation are respectively discharged to predetermined positions on the first preliminary discharge area on the medium. And a first preliminary discharge step.

  The inkjet printer driving method of the present invention includes a second preliminary discharge step for discharging ink from all nozzles of all colors to the second preliminary discharge region on the medium separately from the first preliminary discharge step. In the second preliminary ejection step, it is preferable that the ink is ejected in a pattern in which the ink ejected from all the nozzles does not overlap each other.

  In the ink jet printer driving method of the present invention, separately from the first preliminary ejection step, ink is ejected from at least one nozzle to the third preliminary ejection region on the medium at intervals corresponding to the transport amount of the medium. It is preferable to include a third preliminary discharge step.

  In the ink jet printer of the present invention, the control unit causes the first region of the first preliminary ejection region to eject the color ink used for image formation sequentially in a part of a predetermined position in order, and does not use the color for image formation. Are sequentially ejected to other portions of the predetermined position in order, and the inks of all colors are placed in predetermined positions in the second region different from the first region of the first preliminary ejection region in a predetermined order. It is preferable that the ink is discharged.

  According to the present invention, colors used for image formation and colors not used for image formation can be easily confirmed. In addition, it is possible to reliably know the discharge state of each nozzle, that is, whether there is a discharge failure. Further, it is possible to confirm the conveyance state of the medium, for example, whether or not there is a deviation in the conveyance amount or skew. For this reason, when there is a defect in the formed image, it is possible to quickly analyze and restore the cause of the defect, thereby shortening the time until recovery.

It is the perspective view seen from the front which shows the composition of the ink jet printer concerning the embodiment of the present invention. It is the front view which showed the general | schematic structure of the inkjet head which concerns on embodiment of this invention, a medium, and the periphery. 1 is a block diagram illustrating a configuration of an inkjet printer according to an embodiment of the present invention. FIG. 4 is a plan view showing a positional relationship between a platen, a capping unit, an ink receiver, and a medium according to an embodiment of the present invention. FIG. 5 is a plan view showing a positional relationship among an image forming area, an on-medium preliminary discharge area, a first preliminary discharge area, a second preliminary discharge area, a third preliminary discharge area, and a fourth preliminary discharge area according to an embodiment of the present invention. . It is a flowchart which shows the flow from the setting about preliminary discharge to printing which concerns on embodiment of this invention. It is a conceptual diagram which shows the 1st preliminary discharge pattern in the case of using all 8 colors for image formation. FIG. 5 is a conceptual diagram illustrating a first preliminary ejection pattern when the used colors are four colors Lc, Lm, Gr, and Lgr and the unused colors are four colors K, C, M, and Y. FIG. 6 is a conceptual diagram illustrating a first preliminary ejection pattern when the use colors are six colors Gr, Lgr, K, C, M, and Y and the unused colors are two colors Lc and Lm. FIG. 5 is a conceptual diagram showing a first preliminary ejection pattern when the used colors are three colors of C, M, and Y and the unused colors are five colors of Lc, Lm, K, Gr, and Lgr. It is a conceptual diagram which shows the 1st preliminary discharge pattern in the case of using all four colors for image formation. FIG. 6 is a conceptual diagram illustrating a first preliminary discharge pattern when the used colors are two colors of C and Y and the unused colors are two colors of K and M. It is the elements on larger scale which show an example of nozzle arrangement | positioning of each head which comprises the inkjet head which concerns on embodiment of this invention. It is a conceptual diagram which shows partially an example of the 2nd preliminary discharge pattern which concerns on embodiment of this invention. It is a conceptual diagram which shows partially an example of the 3rd preliminary discharge pattern which concerns on embodiment of this invention. It is a conceptual diagram which shows an example of the preliminary discharge pattern which concerns on the 2nd Embodiment of this invention.

  An inkjet printer and an inkjet printer driving method according to an embodiment of the present invention will be described in detail with reference to the drawings.

  The ink jet printer according to the present embodiment ejects ink while moving on both the outward path from the home position outside the image forming area to the image forming area and the return path from the end position of the outward path to the home position. The present invention forms an image on a medium arranged in an image forming area. However, the present invention can also be applied to an ink jet printer that forms an image on a medium only in the forward path or only in the backward path.

  In the ink jet printer according to the present embodiment, an ink jet head having a predetermined nozzle pitch is divided into a plurality of blocks so as to correspond to the image density on the medium in the medium transport direction. In this ink jet head, each time the carriage is reciprocated, ink is sequentially ejected from each block, and when ink is ejected from all blocks, one image unit is formed. Here, the nozzle pitch is a nozzle interval in the medium transport direction. The number of blocks can be arbitrarily set according to the combination of the nozzle pitch and the image density.

  For example, when the nozzle pitch is 180 dpi, the block used for ejection is changed for each pass in which the inkjet head moves once on the medium, thereby shifting to a position shifted by 720 dpi, which is 1/4 of the nozzle pitch. The ink ejected from the next block lands.

  The ink jet printer according to the present embodiment performs preliminary ejection in an area other than the image forming area on the medium. However, in addition to the preliminary ejection on the medium, the preliminary ejection is performed on an area other than the medium, for example, an ink receiver.

  As shown in FIG. 1, FIG. 2, FIG. 3, or FIG. 4, the inkjet printer 10 according to this embodiment includes an inkjet head 20, a position detection unit 30, a storage unit 50, and a control circuit 60 as a control unit. And comprising. Here, FIG. 1 is a perspective view showing the configuration of the ink jet printer 10 according to the present embodiment as seen from the front. FIG. 2 is a front view showing an overview configuration of the inkjet head 20, the medium M, and the periphery. FIG. 3 is a block diagram illustrating the configuration of the inkjet printer 10. 4 is a plan view showing a positional relationship between the platen 40, the capping unit 41, the ink receiver 42, and the medium M. FIG. Below, the detailed structure of each member is demonstrated.

  As shown in FIG. 2, the inkjet head 20 is mounted on a carriage 21. The carriage 21 is attached to a drive belt 23 that is wound around a pulley 22. The drive belt 23 is driven by a drive motor 24 to reciprocate the carriage 21 in the forward direction S1 and the backward direction S2 parallel to the upper surface of the platen 40 fixed to the fixing unit 12 in the inkjet printer 10. The medium M is conveyed in a direction parallel to the upper surface of the platen 40 and perpendicular to the forward direction S1 and the backward direction S2 of the carriage 21. The inkjet head 20 forms a desired image on the medium M by repeatedly discharging ink and transporting the medium M while moving the carriage 21.

  The inkjet head 20 includes eight heads 20a, 20b, 20c, 20d, 20e, 20f, 20g, and 20h corresponding to eight colors of ink, respectively. These eight heads have the same shape, have a predetermined number of nozzles for ejecting ink below, and eject ink onto the fed medium M. Further, these eight heads are arranged alternately as shown in FIG. Specifically, the heads 20a, 20b, 20c, 20d, 20e, 20f, 20g, and 20h are arranged in this order from the downstream side of the forward direction S1 of the inkjet head 20, and the heads 20a, 20c, 20e, 20g, and 20b are arranged. , 20d, 20f, and 20h are shifted from each other in the conveyance direction of the medium M. Ink is ejected from one or more nozzles of one or more heads depending on the image to be formed.

  As shown in FIGS. 1 and 2, the platen 40 has a long plate shape, and a predetermined distance is provided below the inkjet head 20 in the fixed portion 12 so that the upper and lower surfaces are parallel to the conveyance direction of the medium M. Arranged. A plurality of suction holes (not shown) are formed in the platen 40, and the medium M transported on the platen 40 can be sucked by setting a negative pressure in the suction holes by the operation of a suction device (not shown). it can.

  As shown in FIG. 2, in the fixed portion 12, the ink receiver 42 is disposed outside the platen 40 and the capping unit 41 is disposed outside the ink receiver 42 in the forward direction S <b> 1 and the backward direction S <b> 2 of the carriage 21. Yes. The ink receiver 42 receives ink ejected as preliminary ejection to an area other than the medium M. The capping unit 41 capped the nozzle surface of the inkjet head 20 so as to be airtight, protects the nozzle surface, and sucks ink from each nozzle or discharges ink using a suction device (not shown). Then, the meniscus is adjusted so that the ink in each nozzle is in a desired state.

  As shown in FIG. 3, a head drive circuit 26 is connected to the inkjet head 20, and a carriage drive circuit 27 is connected to the drive motor 24 that drives the carriage 21. The head drive circuit 26 and the carriage drive circuit 27 are connected to a control circuit 60 as a control unit, respectively, and eject ink from predetermined nozzles of the inkjet head 20 while moving the carriage 21 in accordance with an instruction signal from the control circuit 60. Let

  As shown in FIG. 2, the position detection unit 30 includes an encoder 31 and a linear scale 32. The encoder 31 is attached to the carriage 21. The linear scale 32 is provided so as to extend in parallel with the moving direction of the carriage 21. The encoder 31 detects a corresponding scale on the linear scale 32 while moving along the linear scale 32 together with the carriage 21. Since the encoder 31 and the linear scale 32 can use a well-known thing, the detailed description is abbreviate | omitted.

  As shown in FIG. 3, the encoder 31 is connected to the control circuit 60. Information detected by the encoder 31 is output to the control circuit 60, and the control circuit 60 calculates the positions of the carriage 21 and the inkjet head 20 on which the encoder 31 is mounted according to a program stored in a ROM (Read Only Memory) 52 in advance. . The calculated position information is stored in a RAM (Random Access Memory) 53.

  In addition to the head drive circuit 26, carriage drive circuit 27, encoder 31, ROM 52, and RAM 53, the control circuit 60 includes an image data memory 51, a preliminary discharge order memory 54, a preliminary discharge pattern data memory 55, and a preliminary discharge. A setting memory 56, a transport mechanism 46, an IF circuit (interface circuit) 62, and an input / output panel 63 are connected. An external circuit 61 is connected to the IF circuit 62. The image data memory 51, ROM 52, RAM 53, preliminary ejection order memory 54, preliminary ejection pattern data memory 55, and preliminary ejection setting memory 56 constitute a storage unit 50. As the image data memory 51, the preliminary ejection order memory 54, the preliminary ejection pattern data memory 55, and the preliminary ejection setting memory 56, it is preferable to use rewritable storage elements.

  The image data memory 51 stores image data for forming an image in the image forming area P0 on the medium M. Based on the image data stored in the image data memory 51, the control circuit 60 generates drive signals to be given to the heads 20a, 20b, 20c, 20d, 20e, 20f, 20g, and 20h and outputs them to the head drive circuit 26. To do. Further, the control circuit 60 as a used color discriminating unit discriminates the ink color used for image formation and the ink color not used by using the image data stored in the image data memory 51, and the discrimination result is stored in the preliminary ejection order memory. Save to 54.

  In the preliminary ejection order memory 54, in addition to the determination result of the used color by the control circuit 60, for the first preliminary ejection, the color ink used for image formation and the color ink not used for image formation are respectively stored on the medium. The order information for printing in accordance with the predetermined position is stored. This order is, for example, the order of inks of all colors not used for image formation first, and then inks of all colors used for image formation. Conversely, the order of the inks of all colors used for image formation first, and then the inks of all colors not used for image formation may be used.

  The preliminary ejection pattern data memory 55 stores data related to the preliminary ejection pattern for the preliminary ejection area P1 on the medium and the ink receiver 42.

  In the inkjet printer 10 according to the present embodiment, the preliminary ejection pattern data memory 55 stores the following four preliminary ejection patterns. The preliminary discharge pattern of the present invention can be other than these patterns.

(1) Performed on the first preliminary discharge area in the preliminary discharge area P1 on the first preliminary discharge pattern medium, and used for image formation based on the determination result by the control circuit 60 as the use color determination unit. The ink of the color to be used and the ink of the color not to be used for image formation are ejected to a predetermined position in a predetermined order. Here, the pre-discharge area P1 on the medium is an area on the downstream side of the image forming area P0 in the forward direction S1 in which the inkjet head 20 moves, and the first pre-discharge area is an image in the pre-discharge area P1 on the medium. This is a region on the formation region P0 side.

(2) Second preliminary ejection pattern Separate from the first preliminary ejection, ink is ejected from all nozzles of all colors to the second preliminary ejection area in the on-medium preliminary ejection area P1. The second preliminary ejection area for performing the second preliminary ejection is an area in the on-medium preliminary ejection area P1, and is an area downstream of the first preliminary ejection area in the forward direction S1 in which the inkjet head 20 moves. The second preliminary ejection pattern is a pattern in which the ink ejected from all the nozzles can be distinguished from each other on the medium M.

(3) Third preliminary ejection pattern In addition to the first preliminary ejection pattern, ink is supplied from at least one nozzle to the third preliminary ejection area in the on-medium preliminary ejection area P1 at an interval corresponding to the transport amount of the medium. Discharge. The third preliminary ejection area for performing the third preliminary ejection is an area in the on-medium preliminary ejection area P1, and is an area downstream of the second preliminary ejection area in the forward direction S1 in which the inkjet head 20 moves. Note that the confirmation of the transport amount of the medium can also be performed using the second preliminary discharge pattern. In addition, the first preliminary discharge area, the second preliminary discharge area, and the third preliminary discharge area are preferably arranged in this order in the forward direction S1, and executed in this order, but are arranged in another order, It can also be performed in a different order. It is also possible to execute in the backward direction S2 without executing in the forward direction S1.

(4) Ink is simultaneously ejected from all nozzles of all colors to an area outside the fourth preliminary ejection pattern medium M, specifically, the ink receiver 42.

  Preliminary ejection is preferably performed for all of the first to fourth preliminary ejection patterns described above. In particular, it is preferable to always perform the first preliminary discharge and the fourth preliminary discharge even when the image in the image forming region P0 is blank.

  Further, in order to elucidate the cause when the formed image is defective, the second and third preliminary ejections are necessary. The second preliminary discharge pattern is necessary from the viewpoint of confirming the nozzles with defective discharge. Furthermore, from the viewpoint of confirmation of the conveyance failure of the medium M, the third preliminary ejection pattern is necessary.

  The preliminary ejection setting memory 56 stores setting information about which pattern to execute among the first to fourth preliminary ejection patterns. This setting information can be stored at the manufacturing stage of the ink jet printer 10 and can be changed by the user.

  The data stored in the image data memory 51, the preliminary ejection order memory 54, the preliminary ejection pattern data memory 55, and the preliminary ejection setting memory 56 can be input from the input / output panel 63, as well as personal computers and other external devices. The external circuit 61 included in the external device can be input to the control circuit 60 via the IF circuit (interface circuit) 62 and stored in the corresponding memory.

  Here, referring to FIGS. 4 and 5, the image forming area P 0, the on-medium preliminary ejection area P 1, the first preliminary ejection area P 11, the second preliminary ejection area P 12, the third preliminary ejection area P 13, and the ink receiver 42. The operation of the fourth preliminary ejection region P2 corresponding to the above and the inkjet printer 10 will be described. Here, FIG. 5 shows the positional relationship among the image forming area P0, the on-medium preliminary ejection area P1, the first preliminary ejection area P11, the second preliminary ejection area P12, the third preliminary ejection area P13, and the fourth preliminary ejection area P2. FIG.

  The ink jet head 20 is positioned above the capping unit 41 as the home position H when image formation is not being performed, and when driving for image formation is started, the longitudinal direction of the platen 40 is set on the upper surface of the platen 40. It moves in the forward direction S1 or the return direction S2 along the direction. Here, the forward path is a path from the home position H to the forward path end position T outside the platen 40, and the return path is a path that starts from the forward path end position T and reaches the home position H.

  On the other hand, the medium M is transported in the F direction between the platen 40 and the inkjet head 20 by the transport mechanism 46 whose operation is controlled by the control circuit 60. Note that a detailed description of the transport mechanism 46 is omitted. In the ink jet printer 10 according to the present embodiment, in the medium M, an area having a constant width on the forward path end position T side is set as a medium on-preliminary discharge area P1, and a constant width area on the home position H side from the medium on-preliminary discharge area P1. Is an image forming area P0. In other words, the on-medium preliminary ejection area P1 is disposed in an area farther from the home position H than the image forming area P0. Further, a region where ink can be ejected with respect to the ink receiver 42 is a fourth preliminary ejection region P2.

  As shown in FIG. 5, the on-medium preliminary discharge area P1 is arranged in order from the image forming area P0 side in the forward path direction S1, and is a first preliminary discharge area P11, a second preliminary discharge area P12, and a third preliminary discharge area P13. Consists of. The first preliminary ejection region P11, the second preliminary ejection region P12, and the third preliminary ejection region P13 each have a certain width corresponding to the respective ejection pattern. Further, the first preliminary discharge region P11, the second preliminary discharge region P12, and the third preliminary discharge region P13 can be arranged in an order other than that shown in FIG. Further, the on-medium preliminary ejection area P1 may be arranged on the home position H side with respect to the image forming area P0, or divided into two, one at the home position H side and the other from the home position H. It may be arranged on the far side.

  In the ink jet printer 10 having the above configuration, the ink jet head 20 moves from the home position H to the forward path end position T through the fourth preliminary ejection area P2, the image forming area P0, the medium preliminary ejection area P1, and the forward path end. Ink is ejected while moving the carriage 21 on which the inkjet head 20 is mounted on both the return path from the position T to the home position H through the medium preliminary ejection area P1, the image forming area P0, and the fourth preliminary ejection area P2. Then, an image is formed on the image forming area P0 of the medium M. In the following description, the movement of the inkjet head 20 in the forward path and the return path is referred to as a path. In other words, the first movement of the inkjet head 20 in the home position H in the forward direction S1 is the movement of the first pass, and the movement of the inkjet head 20 in the backward direction S2 is the movement of the second pass. The present invention can also be applied to an ink jet printer that prints only when moving in the forward direction. In this case, the number of passes increases by one each time it moves in the forward direction.

  When the inkjet head 20 is moving, the control circuit 60 determines that the position of the inkjet head 20 detected using the position detection unit 30 is the image forming area P0, the first preliminary ejection area P11, and the second preliminary ejection area P12. It is determined which of the third preliminary ejection region P13 and the fourth preliminary ejection region P2 corresponds. The control circuit 60 reads the ink discharge pattern from the preliminary discharge setting memory 56 according to the determined area, and causes the ink jet head 20 to discharge ink with the read ink discharge pattern.

  Next, with reference to FIG. 6, the procedure of printing and preliminary discharge will be described. FIG. 6 is a flowchart showing a flow from setting for preliminary ejection to printing.

  First, the control circuit 60 uses the ink ejection pattern data stored in the image data memory 51 to discriminate between ink colors used for image formation and ink colors not used, and stores the discrimination results in the preliminary ejection order memory 54. (Step S1). The used color and the unused color may be discriminated by using the used color data of the image for printing, which is included in advance in the data sent to the inkjet printer 10 from an external device such as a personal computer. . In this case, the control circuit 60 detects the used color data and determines the color used for printing.

  Subsequently, the control circuit 60 creates order information for first preliminary ejection by arranging the color ink used for image formation and the color ink not used for image formation, and stores them in the preliminary ejection order memory 54 ( Step S2). In this embodiment, this order is the order of ink of all colors not used for image formation first, and then ink of all colors used for image formation. Further, the order among all the unused colors and the order among all the used colors are determined as follows.

  The eight heads 20a, 20b, 20c, 20d, 20e, 20f, 20g, and 20h included in the inkjet head 20 are filled with inks of different colors. The ink colors corresponding to the eight heads are black, cyan, magenta, yellow, light cyan, light magenta, gray, and light gray, and abbreviations are K, C, M, Y, Lc, Lm, Gr, and Lgr, respectively. is there. These inks are assigned color numbers for determining the ejection order, and are stored in the ROM 52 in association with the colors. For example, color numbers 1, 2, 3, 4, 5, 6, 7, and 8 are attached to K, C, M, Y, Lc, Lm, Gr, and Lgr.

  The order of the first preliminary ejection is to first compare the color numbers among all the unused colors, give the first order to the ink with the largest color number, and then to the ink with the next largest color number. Give the order to all colors by repeating giving the order. The ejection order is stored in the preliminary ejection order memory 54 in association with the color. If you set the ejection order for all unused colors, then compare the color numbers among all the used colors, and set the ink with the highest color number next to the last in the unused ink. Repeat and give the next order to the ink with the next highest color number to give an order to all colors. With this procedure, the discharge order of the first preliminary discharge is determined for all colors.

  In the first preliminary ejection, stripe patterns for each color extending in the medium transport direction F are printed in the forward direction S1 in accordance with the ejection order. The first preliminary ejection pattern is formed as a solid image ejected a plurality of times from all nozzles of all colors, and each color pattern has a certain width in the width direction orthogonal to the medium transport direction F. In this way, by ejecting ink from all nozzles for each pass, it is possible to prevent an increase in the viscosity of the ink at the nozzles and to suppress a decrease in image quality. The width of the stripe pattern of each color can be arbitrarily set according to the nozzle shape, ink characteristics, and the like.

  Here, a specific example of the first preliminary ejection pattern will be described with reference to FIGS. FIG. 7 shows that when all eight colors are used for image formation, FIG. 8 shows that the used colors are four colors K, C, M, and Y, and the unused colors are four colors Lc, Lm, Gr, and Lgr. 9 shows that the used colors are six colors Gr, Lgr, K, C, M, and Y, and the unused colors are two colors Lc and Lm. FIG. 6 is a conceptual diagram illustrating first preliminary ejection patterns when there are three colors of K, Gr, and Lgr and the unused colors are five colors of C, M, Y, Lc, and Lm.

  As shown in FIG. 7, when all eight colors are used for image formation, stripe patterns of each color are arranged in descending order of color numbers from the upstream side in the forward direction S1. As shown in FIGS. 8 to 10, when there are colors that are not used for image formation, all the colors to be used are first arranged upstream in the forward direction S1, and among these colors, the colors are in descending order of color numbers. Be placed. Next, all colors that are not used for image formation are arranged in descending order of color numbers.

  The present invention is also applicable to inkjet printers having a number of colors other than eight. 11 and 12 are diagrams showing specific examples of the first preliminary ejection pattern in the case of an ink jet printer having a total of four colors. FIG. 11 shows a case where all four colors are used for image formation, and FIG. 12 shows a first preliminary case where the used colors are K and M, and the unused colors are C and Y. It is a conceptual diagram which shows each discharge pattern. 11 and 12, when there are colors that are not used for image formation, all the colors to be used are first arranged on the upstream side in the forward direction S <b> 1, and among them, the colors are arranged in descending order of color numbers. The Next, all colors that are not used for image formation are arranged in descending order of color numbers.

  Subsequently, in the printing and preliminary discharge procedure shown in FIG. 6, the preliminary discharge pattern is acquired (step S3). For the preliminary ejection pattern, the control circuit 60 reads the preliminary ejection pattern to be used from the preliminary ejection pattern data memory 55 according to the setting information stored in advance in the preliminary ejection setting memory 56.

  The control circuit 60 reads the preliminary ejection pattern from the preliminary ejection pattern data memory 55, reads image data corresponding to the image to be formed in the image forming area P0 from the image data memory 51, and reads these from the image forming area P0 on the medium M. Then, the print patterns arranged in the first preliminary discharge area P11 and the second preliminary discharge areas P12, P13 are created (step S4). The created print pattern is stored in the RAM 53.

  The control circuit 60 sends a drive signal for moving the carriage 21 by a predetermined amount to the carriage drive circuit 27 according to the created print pattern, and sends a medium M to the transport mechanism 46 by a predetermined amount according to the movement of the carriage 21. A drive signal for ejecting ink from a predetermined nozzle is output to the head drive circuit 26 according to the position of the inkjet head 20 with respect to the medium M. As a result, an image corresponding to the print pattern is printed on the medium M (step S5).

  Next, the second preliminary discharge pattern and the third preliminary discharge pattern will be described with reference to FIGS. FIG. 13 is a partially enlarged view showing an example of the nozzle arrangement of each head constituting the inkjet head 20. FIG. 14 is a conceptual diagram partially showing an example of the second preliminary ejection pattern. FIG. 15 is a conceptual diagram partially showing an example of the third preliminary ejection pattern. In FIG. 14, circles indicate positions where ink can land on the medium M, and the case where ink has landed at all positions corresponds to a solid image. Here, a filled circle indicates a position where the ink is landed as the second preliminary discharge, and a non-filled circle indicates a position where the ink is not discharged as the second preliminary discharge. Similarly to FIG. 14, in FIG. 15, circles indicate positions where ink can land on the medium M, and filled circles indicate positions where ink is landed as the third preliminary discharge, and are not painted. A circle indicates a position where ink is not ejected as the third preliminary ejection.

  In the inkjet head 20 according to this embodiment, the nozzle arrangement of each head is common. That is, a predetermined number of nozzles are arranged in the width direction that coincides with the conveyance direction F of the medium M. The nozzle pitch as the interval between these nozzles is the same between all nozzles, and in the example shown in FIG. 13, the interval between the nozzles 20n adjacent in the width direction W is a value corresponding to 180 dpi (dots per inch).

  As shown in FIG. 13, the inkjet head 20 is divided into four blocks B <b> 1, B <b> 2, B <b> 3, and B <b> 4 so as to correspond to 720 dpi that is an image density on the medium M in the conveyance direction F of the medium M. In the inkjet head 20, ink is ejected sequentially from each block each time the carriage 21 is reciprocated. In the first pass in which ink is ejected from the first block B1, ink lands at intervals corresponding to the nozzle pitch, and in the second pass in which ink is ejected from the second block B2, the image is compared with the ink in the first pass. Ink lands at positions with an interval corresponding to the density. Further, in the third pass in which ink is ejected from the third block B3, the ink lands on the second pass ink at a position having an interval corresponding to the image density. Further, in the fourth pass in which ink is ejected from the fourth block B4, the ink lands on the position corresponding to the image density with respect to the ink in the third pass. When ink is ejected from all the blocks in this way, one image unit is formed.

  The medium M is conveyed by an amount corresponding to the image density for each pass. The image forming procedure as described above is repeatedly performed for each image unit in accordance with the print data, whereby a desired image is formed on the medium M.

  The second preliminary discharge pattern and the third preliminary discharge pattern are executed for each image unit. In the second preliminary ejection pattern illustrated in FIG. 14, ink is ejected from all nozzles of all heads in the first pass, and ink is not ejected in the second to fourth passes. When ink is ejected in such a pattern, each of the landed inks can be easily identified, so that it is easy to check whether ink ejection is good or not, and ink consumption can be suppressed.

  The second preliminary ejection pattern is not limited to the example shown in FIG. 14 and may be any pattern as long as the inks do not overlap each other. For example, all nozzles of the first block B1 in the first pass, all nozzles of the second block B2 in the second pass, all nozzles of the third block B3 in the third pass, and fourth block B4 in the fourth pass Ink is discharged from all nozzles. In this case as well, ink is ejected in a pattern that does not overlap the ink from each nozzle, and it is easy to identify each ink that has landed. Therefore, it is easy to check the quality of ink ejection and to reduce ink consumption. Can do.

  In the third preliminary ejection pattern shown in FIG. 15, ink is ejected from the nozzles at a predetermined interval in the scanning direction in the first pass. Ink is not ejected from the second pass to the fourth pass. Further, as shown in FIG. 15, printing is performed so that the ejection of ink is staggered for each image unit in the scanning direction. When ink is ejected in such a pattern, it becomes easier to measure the interval of ink ejected from the same nozzle for each image unit or for each nozzle pitch in the transport direction F. The comparison becomes easy and the ink consumption can be suppressed. The third preliminary ejection pattern is not limited to the example illustrated in FIG. 15, and may be any pattern that can measure the interval in the transport direction F of the ink that has landed on the medium M. Therefore, the number of nozzles that eject ink is not limited to two as in the pattern shown in FIG. 15, and may be one, or three or more.

  The second preliminary discharge pattern can also be used as a third preliminary discharge pattern depending on the pattern.

  In addition, the first preliminary discharge is preferably performed at each pass from the viewpoint of preventing increase in the viscosity of the ink, but the second preliminary discharge and the third preliminary discharge may be performed at a predetermined number of passes. It may be performed only when the user gives an instruction by operating the input / output panel 63 or an external device including the external circuit 61.

  FIG. 16 is a conceptual diagram showing an example of a preliminary ejection pattern according to the second embodiment of the present invention. An image is formed on the image forming area P0 on the medium M, and preliminary ejection is performed on the preliminary ejection area P1 on the medium M. This is related to image formation and preliminary ejection at the end portion of the image. The ink jet head is divided into four parts and the ejection is controlled. Head positions 64, 65, 66, and 67 indicate the relative positional relationship between the medium M and the inkjet head. The 1st head part 71, the 2nd head part 72, the 3rd head part 73, and the 4th head part 74 have shown the divided | segmented part of the inkjet head.

  The image formation on the image forming region P0 is completed by scanning when the ink jet head is at the head position 67. At the head position 64, an image is formed on the image forming area P0 using all the divided portions of the ink jet head. Thereafter, the medium M is transported, and the relative position between the inkjet head and the medium M becomes a relationship indicated by the head position 65. At this time, an image is formed in the image forming region P0 using the first head unit 71, the second head unit 72, and the third head unit 73, and the first head unit 71 and the second head are formed in the preliminary ejection region P1. Preliminary ejection is performed using the section 72, the third head section 73, and the fourth head section 74.

  Thereafter, the medium M is transported, and the relative position between the inkjet head and the medium M becomes a relationship indicated by a head position 66. At this time, an image is formed on the image forming area P0 using the first head section 71 and the second head section 72, and the first head section 71, the second head section 72, and the third head are formed on the preliminary ejection area P1. Preliminary discharge is performed using the portion 73 and the fourth head portion 74.

  Thereafter, the medium M is transported, and the relative position between the inkjet head and the medium M becomes a relationship indicated by the head position 67. At this time, the first head unit 71 is used to form an image in the image forming region P0, and the first head unit 71, the second head unit 72, the third head unit 73, and the fourth head are formed in the preliminary ejection region P1. Preliminary discharge is performed using the portion 74.

  The preliminary ejection second portion 68 is preliminary ejected by the second head portion 72, the third head portion 73, and the fourth head portion 74. The preliminary ejection third portion 69 is preliminary ejected by the third head portion 73 and the fourth head portion 74. The preliminary ejection fourth portion 70 is preliminary ejected by the fourth head unit 74.

  When the ink jet head is divided into a plurality of parts, here, divided into four parts, the end portion of the image is formed by using a part of the ink jet head. However, the preliminary ejection is performed using all the nozzles of the inkjet head.

  Preliminary ejection before the head position 64 will be described. The order of the first preliminary ejection is the order in which all colors are used, that is, the color numbers are first compared among all the colors used, and the ink having the next largest color number is compared with the ink having the largest color number. Repeat giving the next order to give an order to all colors. With this procedure, the discharge order of the first preliminary discharge is determined for all colors. The ejection order is stored in the preliminary ejection order memory 54 in association with the color.

  In the first preliminary ejection, stripe patterns for each color extending in the medium transport direction F are printed in line according to the ejection order stored in the preliminary ejection order memory 54 in the forward direction S1.

  Next, preliminary ejection from the head position 65 to the head position 67 will be described.

  The first head part 71, the second head part 72, the third head part 73 in the case of the head position 65, the first head part 71 in the case of the head position 66, the second head part 72, the first in the case of the head position 67. The preliminary ejection of a predetermined portion of the ink jet head in each case of the head unit 71 is the same as the preliminary ejection before the head position 64 described above.

  Next, the fourth head portion 74 in the case of the head position 65, the third head portion 73 in the case of the head position 66, the fourth head portion 74, the second head portion 72 in the case of the head position 67, and the third head portion. 73 and preliminary ejection of a predetermined portion of the inkjet head in each case of the fourth head portion 74 will be described.

  The order of the first preliminary ejection is as follows. First, the color numbers are compared among all the unused colors for the image formed in the image forming area P0, and the first order is given to the ink having the largest color number. Repeat to give the next order to the ink with the next largest color number, giving an order to all colors. Next, when the ejection order is assigned to all the unused colors for the image formed in the image forming area P0, the color numbers are compared among all the used colors, and the ink having the largest color number is selected. Repeat the process of giving the next order to the last order in the unused ink and giving the next order to the ink with the next highest color number to give an order to all colors. With this procedure, the discharge order of the first preliminary discharge is determined for all colors. The ejection order is stored in the preliminary ejection order memory 54 in association with the color.

  In the first preliminary ejection, stripe patterns for each color extending in the medium transport direction F are printed in line according to the ejection order stored in the preliminary ejection order memory 54 in the forward direction S1.

  In this manner, by performing preliminary ejection, it is possible to easily compare the color ink used for image formation and the color ink usable for image formation in different areas. That is, the comparison can be easily made by looking at the preliminary ejection region P1 at the image end. In the second area, that is, the used color discriminating units 68, 69, and 70 and the first area, that is, the usable color discriminating unit 75, the display of the stripe pattern changes, so it is easy to determine what color is used for printing Compare and judge. The display of usable ink colors and the ink color used in the actually printed image can be easily determined.

  In the above example, the use color discrimination stripe is displayed in the part that does not support image printing, and the pattern in which the use color is not discriminated is displayed in the other part. Good.

With the configuration described above, the following effects are achieved according to the above embodiment.
(1) With the first preliminary ejection, the colors used for image formation and the colors not used can be easily confirmed, and since ejection is performed from all nozzles, an increase in ink viscosity is prevented for nozzles that are not particularly used. Can do.
(2) By the second preliminary discharge, it is possible to check the discharge state and the ink state for all nozzles.
(3) The conveyance state of the medium M can be confirmed by the third preliminary discharge.
(4) Since the first, second, and third preliminary discharges can analyze the element that may cause when the formed image is defective, the recovery operation can be performed quickly. It becomes possible.

  Although the present invention has been described with reference to the above embodiment, the present invention is not limited to the above embodiment, and can be improved or changed within the scope of the purpose of the improvement or the idea of the present invention.

  As described above, the inkjet printer and the inkjet printer driving method according to the present invention are useful for inkjet printers that perform preliminary ejection in addition to ejection for image formation, and in particular, the size of a medium that is an object of image formation is large. Suitable for inkjet printers.

DESCRIPTION OF SYMBOLS 10 Inkjet printer 12 Fixed part 20 Inkjet head 20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h Head 20n Nozzle 21 Carriage 22 Pulley 23 Drive belt 24 Drive motor 26 Head drive circuit 27 Carriage drive circuit 30 Position detection part 31 Encoder 32 Linear scale 40 Platen 41 Capping unit 42 Ink receiver 46 Transport mechanism 50 Storage unit 51 Image data memory 52 ROM
53 RAM
54 Preliminary ejection sequence memory 55 Preliminary ejection pattern data memory 56 Preliminary ejection setting memory 60 Control circuit 61 External circuit 62 IF circuit 63 Input / output panel B1 First block B2 First block B3 First block B4 First block F Transport direction H Home Position M Medium P0 Image forming area P1 Medium pre-discharge area P11 First pre-discharge area P12 Second pre-discharge area P13 Third pre-discharge area P2 Fourth pre-discharge area S1 Forward direction S2 Return direction T Outward end position

Claims (18)

A plurality of inkjet heads that form an image in an image forming area on a medium by ejecting ink while reciprocating in accordance with an input drive signal, and the plurality of inkjet heads eject inks of different colors An inkjet printer,
A use color discriminating unit for discriminating between the ink color used in image formation in the image forming region and the ink color not used;
Based on the determination result by the use color determination unit, the color ink used for the image formation and the color ink not used for the image formation are respectively set at predetermined positions with respect to the first preliminary ejection area on the medium. A controller that causes the inkjet head to perform a first preliminary ejection to be ejected;
An ink jet printer comprising:   2. The ink jet printer according to claim 1, wherein the control unit rearranges predetermined positions of the respective colors in a predetermined order based on a determination result by the use color determination unit.   The inkjet printer according to claim 2, wherein the predetermined order is an order of ink of all colors not used for the image formation first, and then ink of all colors used for the image formation.   The first preliminary ejection is performed such that the ink ejected from the nozzles of each color has a certain width in the width direction of the medium and has a stripe shape extending in the transport direction of the medium. Inkjet printer.   The inkjet printer according to claim 4, wherein the first preliminary ejection is performed for all nozzles of all colors.   The inkjet printer according to claim 5, wherein the first preliminary ejection area is located downstream of the image forming area in a forward direction in which the inkjet head moves.   The control unit causes the inkjet head to perform a second preliminary discharge for discharging ink from all nozzles of all colors to the second preliminary discharge region on the medium separately from the first preliminary discharge, 2. The ink jet printer according to claim 1, wherein the second preliminary ejection is performed in a pattern in which the ink ejected from all the nozzles does not overlap each other.   The inkjet head is divided into a predetermined number of blocks corresponding to the image density in the conveyance direction of the medium, and each image unit is ejected in order from each block each time the inkjet head is reciprocated. The inkjet printer according to claim 7, wherein the second preliminary ejection is performed by ejecting ink for each image unit for each nozzle.   The inkjet printer according to claim 8, wherein the second preliminary ejection region is downstream of the first preliminary ejection region in the forward direction in which the inkjet head moves.   In addition to the first preliminary ejection, the control unit ejects ink from at least one nozzle to a third preliminary ejection area on the medium at an interval corresponding to the transport amount of the medium. The ink jet printer according to claim 1, wherein the ink jet head performs ejection.   The inkjet printer according to claim 10, wherein the third preliminary ejection is performed each time the inkjet head is moved on the medium.   The inkjet head is divided into a predetermined number of blocks corresponding to the image density in the conveyance direction of the medium, and each image unit is ejected in order from each block each time the inkjet head is reciprocated. The inkjet printer according to claim 10, wherein the third preliminary ejection is performed by ejecting ink for each image unit with respect to a predetermined nozzle.   The inkjet printer according to claim 10, wherein the third preliminary ejection region is downstream of the second preliminary ejection region in the forward direction in which the inkjet head moves.   2. The inkjet printer according to claim 1, wherein the control unit causes the inkjet head to perform a fourth preliminary ejection for ejecting ink from all nozzles of all colors to a region outside the medium. A plurality of inkjet heads that form an image in an image forming area on a medium by ejecting ink while reciprocating in accordance with an input drive signal, and the plurality of inkjet heads eject inks of different colors A method of driving an inkjet printer,
Based on the drive signal, a use color discrimination step for discriminating between an ink color used for image formation in the image forming region and an ink color not used;
Based on the determination result by the use color determination unit, the color ink used for the image formation and the color ink not used for the image formation are respectively set at predetermined positions with respect to the first preliminary ejection area on the medium. A first preliminary discharge step for discharging;
A method for driving an ink jet printer, comprising:   In addition to the first preliminary ejection step, the second preliminary ejection step includes ejecting ink from all nozzles of all colors to the second preliminary ejection region on the medium. In the second preliminary ejection step, The ink jet printer driving method according to claim 15, wherein the ink is ejected in a pattern such that the ink ejected from all the nozzles does not overlap each other.   In addition to the first preliminary ejection step, a third preliminary ejection step for ejecting ink from at least one nozzle to the third preliminary ejection region on the medium at an interval corresponding to the transport amount of the medium is provided. The method for driving an ink jet printer according to claim 15.   The control unit causes the color ink used for the image formation to be successively ejected to a part of the predetermined position in the first region of the first preliminary ejection region, and the color ink not used for the image formation. Are sequentially discharged to other portions of the predetermined position, and ink of all colors is predetermined at the predetermined position in a second region different from the first region of the first preliminary discharge region. The ink jet printer according to claim 1, wherein the ink jet printer is sequentially ejected.

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