JP2013223926A - Inkjet recording apparatus and recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet recording apparatus capable of properly performing preliminary ejection to a recording medium with a low-cost configuration while suppressing deterioration in image quality.SOLUTION: An inkjet recording apparatus performs medium preliminary ejection that ejects ink that does not contribute to recording of an image from a recording heat to a recording medium based on preliminary ejection data. The medium preliminary ejection ejects ink of nozzles in a nozzle array position at the same overlapped part of adjacent recording heads based on the same medium preliminary ejection pattern data.

Description

  The present invention records an image by ejecting ink from a nozzle of a recording head onto a recording medium, and maintains the ejection performance of the nozzle by ejecting ink that does not contribute to image recording from the nozzle of the recording head. The present invention relates to an ink jet recording apparatus that enables the above.

  Currently, a full-line type inkjet recording apparatus is known as an inkjet recording apparatus suitable for high-speed recording. In this full-line type ink jet, a recording head in which nozzles for ejecting ink are arranged in a direction perpendicular to the transport direction of the recording medium is used, and ink is ejected from the recording head to the continuously transported recording medium. And record. The length of the nozzle row arranged in the recording head needs to be equal to or greater than the maximum value of the width of the recording medium to be used (the length in the direction orthogonal to the conveyance direction of the recording medium). However, in order to integrally form such a long nozzle row, technical and cost problems arise. For this reason, normally, a nozzle row having a required length is configured by arranging a nozzle row shorter than the required nozzle arrangement width along the direction orthogonal to the transport direction. .

  Patent Document 1 discloses a configuration in which a plurality of head chips on which nozzle rows are formed are arranged along a direction orthogonal to the conveyance direction of a recording medium. Each head chip is arranged in a state where the respective end portions thereof are overlapped with each other in the transport direction. This is because when an unnecessarily large gap is formed between the end portions of each nozzle row due to an arrangement error of each head chip, a portion where ink is not applied is formed on the recording medium, and the portion has a streak-like density. This is because it appears as unevenness (white stripes).

  On the other hand, in an ink jet recording apparatus, in order to maintain and recover the ejection performance of each nozzle of the recording head, ink ejection that does not contribute to image recording, which is called preliminary ejection, is performed. In particular, in a full-line type ink jet recording apparatus, so-called preliminary paper ejection is performed to eject ink onto a recording medium. However, if the paper surface preliminary discharge is performed for all the nozzles, the nozzles at the end of the nozzle row overlap each other, so the number of discharges of the paper surface preliminary discharge in the overlapping area (overlapping area) overlaps each other. More than the number of discharges in the non-overlapping area (non-overlapping area). For this reason, the density of the portion recorded in the overlapping area becomes higher than the density of the portion recorded in the non-overlapping area, causing a problem that the image quality is deteriorated. Thus, it has been proposed to perform preliminary ejection on the conveyor belt for the nozzles in the overlapping area and perform preliminary ejection on the paper for the nozzles in the non-overlapping area.

JP 2010-137388 A

  However, in order to perform preliminary paper ejection on the conveyor belt, it is necessary to make the ink landing part of the conveyor belt water-repellent and to provide a means for cleaning the part. There is a problem that the cost increases. It has also been proposed to employ a configuration in which an opening for sucking ink preliminarily ejected on the paper surface is provided in the transport belt and ink is sucked from the opening. However, in this case, there is a problem that a waste ink receiver (waste ink tank) for receiving the sucked ink is required, resulting in an increase in cost. Preliminary ejection with respect to the conveyance belt can be performed when the recording medium is cut paper, but when continuous paper is used, the conveyance belt immediately below the head is always covered with continuous paper, and thus cannot be performed. There is also a problem.

  The present invention has been made paying attention to the above problems, and provides an ink jet recording apparatus and an ink jet recording method capable of appropriately performing preliminary ejection onto a recording medium with an inexpensive configuration while suppressing deterioration in image quality. With the goal.

In order to achieve the above object, the present invention has the following configuration.
In other words, according to the first aspect of the present invention, the conveying unit that conveys the recording medium along a certain conveying direction, and at least two nozzle rows in which a plurality of nozzles that eject ink of the same color are arranged include the conveying unit. A recording head that is arranged along a direction that intersects the direction and that has overlapping portions in which end portions of adjacent nozzle rows overlap each other in the transport direction, and performs recording by ejecting ink from the recording head. An ink jet recording apparatus, comprising: medium preliminary discharge means for performing medium preliminary discharge for discharging ink that does not contribute to image recording from the recording head to the recording medium based on preliminary discharge pattern data; The means discharges ink from nozzles located in the same overlapping portion based on the same medium preliminary discharge pattern data. And features.

  According to a second aspect of the present invention, a conveying unit that conveys a recording medium along a certain conveying direction, and at least two nozzle arrays in which a plurality of nozzles that eject ink of the same color are arranged are arranged in the conveying direction. An inkjet that performs recording by ejecting ink from the recording head, the recording head having an overlapping portion that is arranged along the intersecting direction and in which the end portions of the adjacent nozzle rows overlap each other in the transport direction A medium preliminary ejection step for performing a medium preliminary ejection for ejecting ink that does not contribute to image recording from the recording head to the recording medium based on preliminary ejection pattern data. Discharge ink of nozzles in nozzle rows located in the same overlapping portion based on the same medium preliminary discharge pattern data And wherein the Ukoto.

  According to the present invention, since ink is ejected from nozzles located in overlapping portions of adjacent nozzle rows based on the same medium preliminary ejection pattern data, quality deterioration of an image formed on a recording medium is reduced. And a high-quality image can be formed. Further, since a special configuration for processing ink is not required, the configuration can be made at low cost.

1 is a perspective view illustrating an ink jet recording apparatus according to a first embodiment. It is sectional drawing which shows the inkjet recording device in 1st Embodiment. FIG. 2 is a perspective view illustrating a recording head unit and an arrangement of the recording head provided in the ink jet recording apparatus according to the first embodiment. FIG. 3 is a diagram schematically illustrating nozzle arrays of two recording heads that eject a certain color of ink and an array of dots of an image recorded by the nozzle arrays in the first embodiment. FIG. 2 is a block diagram illustrating a schematic configuration example of a control system provided in the ink jet recording apparatus according to the first embodiment. It is a schematic diagram which shows the conventional medium preliminary discharge data. FIG. 6 is a schematic diagram for explaining medium preliminary ejection performed on both head passage areas 505 by overlapping nozzle areas of two recording heads. It is the figure which expands and shows the conventional adjacent dots 701 and 702, (a) is a top view, (b) is sectional drawing. It is a schematic diagram which shows the medium preliminary discharge data in embodiment. FIG. 6 is a schematic diagram for explaining medium preliminary ejection performed on both head passing areas by overlapping nozzle regions of two recording heads. 2A and 2B are enlarged views illustrating dots formed by nozzles in an overlapping nozzle region of a recording head, in which FIG. 2A is a plan view and FIG. 2B is a cross-sectional view. 6 is a flowchart illustrating a control procedure of a recording operation executed by a control unit of the ink jet recording apparatus according to the first embodiment. FIG. 9 is a diagram schematically illustrating nozzle arrays of two recording heads that eject ink of a certain color in the second embodiment and an array of dots of an image recorded by the nozzle arrays. FIG. 10 is a schematic diagram for explaining medium preliminary ejection performed on both head passing areas by overlapping nozzle regions of two recording heads in the second embodiment. It is a schematic diagram for demonstrating the conventional medium preliminary discharge.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. In addition, the component described in the following embodiment is an illustration to the last, and is not the thing of the meaning which limits the scope of the present invention only to them.

  FIG. 1 is a perspective view showing an ink jet recording apparatus (hereinafter also simply referred to as a recording apparatus) in the present embodiment. The ink jet recording apparatus 100 includes a recording apparatus main body 101 provided with an operation unit 102 and a roll paper holder 103. In the roll paper holder 103, a roll paper 200R configured with continuous paper is incorporated. The recording apparatus 100 conveys the continuous paper 200 fed from the roll paper 200R, which is a recording medium, to the continuous paper 200 or the label paper 401 (see FIG. 3) affixed to the continuous paper 200 from the host computer 104. An image is recorded based on the received image data. The inkjet recording apparatus 100 and the host computer 104 are connected by a printer cable 105.

  FIG. 2 is a cross-sectional view illustrating the ink jet recording apparatus 100 according to the present embodiment. In the inkjet recording apparatus 100, a roll paper 200 that is a recording medium built in the roll paper holder 103 is placed on a pair of roll paper conveyance rollers 206. When the roll paper transport roller 206 rotates, the roll paper 200R rotates, and the continuous paper 200 is fed out from the roll paper 200R and supplied to the recording apparatus main body 101. Further, the recording apparatus main body 101 is provided with a conveying means including a conveying roller 203 and an endless conveying belt 204 stretched around the conveying roller 203. The continuous paper 200 fed from the roll paper 200R is conveyed in the Y direction by the conveying belt 204 of the conveying means.

  A plurality of recording heads 211 and 212 are arranged along the conveyance direction at positions facing the recording medium conveyance surface of the conveyance belt 204. In this embodiment, two recording head units 201 and 202 as shown in FIGS. 2 and 3 are provided. Each of the recording head units 201 and 202 holds one recording head that discharges ink of each color of yellow (Y), magenta (M), cyan (C), and black (B). The ink cartridges 205 for the respective colors are disposed below the conveying belt 204 in the recording apparatus main body 101, and are connected to the corresponding recording heads 211 and 212 by a flexible tube (not shown).

  FIG. 3 is a perspective view showing the arrangement of the recording head unit and the recording head provided in the main body 101. The two recording head units 201 and 202 mounted in the recording apparatus main body 101 are different from each other in the transport direction (Y direction) and the direction intersecting the transport direction (Y direction) (the direction orthogonal to the figure (X direction)). Placed in position. However, the recording head units 201 and 202 are arranged so that their end portions overlap in the transport direction of the continuous paper 200 fed from the roll paper 200R. Each recording head unit 201, 202 holds a recording head 211 (211K, 211C, 211Y, 211M) and a recording head 212 (212K, 212C, 212Y, 212M). The recording heads 211 and 212 eject ink from nozzles 506 and 507 arranged in a line in each. As a result, an image is formed on the label 401 affixed to the continuous paper 200 that passes directly under each nozzle. Also, it is possible to recover and maintain the ejection performance of each nozzle of the recording head by ejecting ink (medium preliminary ejection) from each nozzle to the recording medium (label 401) without contributing to image recording. Become.

  FIG. 4 is a diagram schematically showing the nozzle arrays of two recording heads that eject ink of a certain color and the dot arrangement of an image recorded by these nozzle arrays in the present embodiment. As shown in the drawing, the nozzle array of the recording head 211 in the upstream recording head unit 201 and the nozzle array of the recording head 212 in the downstream recording head unit 202 are each at one end portion in the recording medium conveyance direction (Y In the direction). That is, the nozzle located at one end portion (right end portion in the figure) of the nozzle row in the recording head 211 and the nozzle located at the left end portion (left end portion in the figure) of the recording head 212 are at the same position in the X direction. is there. In this way, in each of the upstream and downstream nozzle rows, a portion (overlapping portion) 510 where both nozzle rows overlap in the Y direction is referred to as an overlapping nozzle region, and portions 511 and 512 other than the overlapping nozzle region 510 are non-overlapping nozzles. This is called an area. By providing the overlapping nozzle region 510 in this way, registration adjustment of the joint portion of images recorded by both nozzle rows can be performed. In addition, it is possible to prevent the image quality from being deteriorated at the connected portion of the image due to the difference in the ink discharge amount that varies depending on the recording head 201.

  As shown in FIG. 4, an area 503 (upstream head passage area) in the label 401 that passes only directly below the non-overlapping nozzle region 511 in the recording head 211 (upstream recording head) is in the upstream recording head 211. A nozzle 506 ejects ink to form dots 501. Further, in the area 505 (downstream head passage area) in the label 401 that passes only directly below the non-overlapping nozzle region 512 in the recording head 212 (downstream recording head), the nozzle 507 in the downstream recording head 201 is ink-filled. To form dots 502.

  Further, the label area 505 that passes immediately below the overlapping nozzle region 510 where the nozzle row of the upstream recording head 211 and the nozzle row of the downstream recording head 212 overlap is formed by the dots 501 by the nozzles 506 and 507 in the overlapping nozzle region 510. , 502 are recorded. In the following description, the area 505 is referred to as a both head passage area. In FIG. 4, the nozzles 506 and 507 of the recording heads 211 and 212 form dots 501 and 502 every other dot in the transport direction (Y direction) and the orthogonal direction (X direction), respectively. Thus, dots 501 and 502 are alternately formed in both the X and Y directions. That is, the image formed by the dots 501 and the image formed by the dots 502 are interpolated with each other.

  As described above, by forming an image with the recording heads 211 and 212 in both the head passage areas 505, it is possible to prevent the image quality at the joint portion of the images from being deteriorated due to the difference in the ink discharge amount of each recording head. In the above description, the case where an image is recorded by the recording heads 211 and 212 that discharge ink of one color in the recording head unit has been described, but the recording heads 211 and 212 of other three colors are used. In this case, recording is performed by ejecting dots in the same manner.

  By the way, an error occurs between the number of nozzles corresponding to the designed print head overlap area 505 and the number of nozzles corresponding to the print head overlap area 510 in the print head units 201 and 202 installed in the actual printing apparatus. Sometimes. This error varies depending on structural tolerances and mounting errors of the head units 201 and 202 and the recording heads 211 and 212 provided therein. The difference is corrected by the above-described registration adjustment of the connecting portion of the image. That is, the overlapping nozzles in the transport direction can be specified from the result of the registration adjustment of the image connection part. However, in practice, the nozzles in the recording heads do not completely overlap in the transport direction and exist in a slightly shifted state. Accordingly, in this specification, the nozzles of the respective recording heads that are closest to the raster to be formed are referred to as overlapping nozzles that overlap in the transport direction in order to form the raster.

  FIG. 5 is a block diagram illustrating a schematic configuration example of a control system in the ink jet recording apparatus according to the present embodiment. The control unit 300 includes a central processing unit (CPU) 301, and controls each peripheral device by executing a control program stored in a nonvolatile memory (ROM) 302. The control unit 300 also includes a memory (RAM) 303 used as a work area for various data processing and a reception buffer, an image memory 304 used as an image development unit, and the like. The control unit 300 further includes a control circuit 311 that controls a head driving circuit 305 that drives the recording head 201, a motor driver 307 that drives various motors 306 that are a power source for the recovery operation and recording operation of the recording head 201, and the like. . Further, the control unit 300 is configured to control the control unit (I / O) 309 of the transport sensor 308 via the control circuit 311.

  The recording apparatus basically includes a USB controller 310 that receives recording data, a recovery command, and the like transmitted from the host computer 104 via a printer cable 105 such as a USB. Then, the CPU 301 and the control circuit 311 control the operation of each unit in accordance with various command commands received by the USB controller 310. The interface is not limited to USB. The controller 300 constitutes medium preliminary ejection means for causing the recording head to perform medium preliminary ejection.

  Next, medium preliminary ejection performed in the present embodiment will be described. In the following description, in order to clarify the difference between the medium preliminary ejection that has been conventionally performed and the medium preliminary ejection in the present embodiment, first, conventional medium preliminary ejection is described, and then, in this embodiment. The medium preliminary discharge to be performed will be described.

  FIG. 6 is a diagram showing conventional bitmap pattern data for preliminary ejection of medium (hereinafter referred to as medium preliminary ejection data). The medium preliminary ejection data 601 is stored in a nonvolatile memory (ROM) 302, and is developed in the image memory 304 together with image data to be recorded when used. The medium preliminary ejection data 601 developed in the image memory 304 includes ejection data 602 for instructing ejection of ink droplets for forming dots and non-ejection data 603 for not instructing ejection of ink droplets. As shown in FIG. 6, the ejection data 602 are not adjacent to each other in the nozzle arrangement direction (X direction) and the transport direction (Y direction) of the recording head 201, and are arranged at regular intervals through a certain interval. Has been. According to the ejection data 602 of the medium preliminary ejection data 601, preliminary ejection is performed on the recording medium from all the nozzles of all the recording heads 201. This medium preliminary ejection is performed together with the recording operation according to the medium preliminary ejection data developed in the image memory 304. That is, preliminary ejection to the recording medium is performed while forming an image. When the recording operation proceeds and the medium preliminary ejection data is depleted, the medium preliminary ejection data is transferred again from the head to the recording head.

  FIG. 7 is a schematic diagram for explaining medium preliminary ejection performed on both head passage areas 505 by the overlapping nozzle region 510 of the recording heads 211 and 212. Conventionally, medium preliminary ejection is performed by ejecting ink from the upstream recording head 211 and the downstream recording head 212 based on the medium preliminary ejection data 601. In FIG. 7, a dot 501 is a dot formed by the recording head 211, and a dot 502 is a dot formed by the recording head 212. The same preliminary ejection data 601 is input to the upstream recording head 211 and the downstream recording head 212, respectively. Accordingly, the preliminary ejection performed by each recording head 211 and recording head 212 in both head passage areas 505 is performed based on different medium preliminary ejection data 601. For example, the recording head 211 performs recording based on the ejection data 602 in the area indicated by R1 in the medium preliminary ejection data 601 shown in FIG. On the other hand, the recording head 212 performs recording based on the ejection data 602 in the region indicated by R2. For this reason, the ink droplets preliminarily ejected from each recording head land on different positions in both head passing areas 505. In FIG. 7, dots 501 formed in both head passage areas 505 by the upstream recording head 201 and dots 502 formed in both head passage areas 505 by the downstream recording head 201 are formed at positions adjacent to each other in the nozzle arrangement direction. Has been.

  FIGS. 8A and 8B are enlarged views showing the conventional adjacent dots 701 and 702 shown in FIG. 7, wherein FIG. 8A is a plan view and FIG. 8B is a cross-sectional view. As shown in FIG. 8, when dots 701 and 702 are formed adjacent to each other, both dots are recognized as one large dot and become conspicuous in the image. If the dots formed by the preliminary ejection are conspicuous, there arises a problem that the image quality is deteriorated by the dots. In addition, when the combination of the recording medium (label 401) and the ink is a combination in which the ink is difficult to bleed as shown by the cross-sectional dots 701 and 702, the spread of the dot diameter can be suppressed. In this case, since the ink does not penetrate into the label 401 and is on the surface of the label 401, the density of the dots 701 and 702 increases, and the dots become more noticeable in the image.

  FIG. 9 is a schematic diagram showing bit map pattern data (medium preliminary ejection data) for medium preliminary ejection in the present embodiment. The medium preliminary ejection data 901 is stored in a non-volatile memory (ROM) 302 and is expanded in the image memory 304 when used. The medium preliminary ejection data 901 includes ejection data 602 and non-ejection data 603. The ejection data 602 are not adjacent to each other in the nozzle arrangement direction (X direction) and the transport direction (Y direction) of the recording head 201, and are arranged so as to be equidistant from each other with a constant interval.

  In the medium preliminary discharge data 901, the discharge data in the area 902 indicates discharge data for causing all nozzles of the upstream recording head 201 to perform medium preliminary discharge. Further, the discharge data in the area 903 indicates discharge data for causing all the nozzles of the downstream recording head 212 to perform medium preliminary discharge. Further, the ejection data in the area 904 indicates ejection data for executing medium preliminary ejection in the overlapping nozzle area 510 where the upstream recording head 211 and the downstream recording head 212 overlap in the transport direction. Also in the present embodiment, the medium preliminary ejection is performed together with the recording operation according to the medium preliminary ejection data developed in the image memory 304. That is, preliminary ejection to the recording medium is performed while forming an image. When the recording operation proceeds and the medium preliminary discharge data is exhausted, the medium preliminary discharge data is transferred again from the head to the drive circuit of the recording head.

  In this embodiment, the medium preliminary ejection data 601 is stored in the nonvolatile memory (ROM) 302 and is expanded in the image memory 304 when used. However, the medium preliminary ejection data 601 developed in the image memory 304 can also be generated by arithmetic processing, and is not limited to the method using the data stored in the nonvolatile memory (ROM) 302 in advance as described above. .

  Conventional bit map pattern data 601 for preliminary ejection of medium is data for the number of nozzles provided in one recording head 211 or 212. On the other hand, the bitmap pattern data 901 for preliminary ejection of medium in the present embodiment is obtained by subtracting the number of nozzles in one recording head in the overlapping nozzle area 510 from the number of nozzles provided in the two recording heads 211 and 212. Data for the number of nozzles. That is, the data for the number of nozzles in a row arranged in the maximum width area that can be recorded on the recording medium by the recording heads 211 and 212 is obtained. In addition, the medium preliminary ejection data 902 corresponding to the upstream head passage area 503 is used to adjust the registration of the connecting portion between the nozzles arranged in the designed recording head overlap area 505 and the images recorded by both heads. Can be obtained from the results. The result of adjusting the registration of the image connection portion is stored in a nonvolatile memory (ROM) 302.

  FIG. 10 is a schematic diagram for explaining medium preliminary ejection performed on both head passage areas 505 by the overlapping nozzle region 510 of the recording heads 211 and 212. In the present embodiment, medium preliminary ejection of the upstream recording head 211 and the downstream recording head 212 is performed based on the medium preliminary ejection data 901. That is, the medium preliminary ejection of the upstream recording head 211 is performed based on the data in the area 902 among the medium preliminary ejection data 901, and the medium preliminary ejection of the downstream recording head 212 is performed based on the data in the area 903. Is called.

  In FIG. 10, a dot 701 is a dot formed by the recording head 211, and a dot 702 is a dot formed by the recording head 212. The medium preliminary ejection data 901 is data having continuity regularly arranged in the nozzle arrangement direction (X direction) and the conveyance direction (Y direction) as shown in FIG. Based on the ejection data located in the area 904 in the preliminary ejection data, the medium preliminary ejection of the nozzles located in the overlapping nozzle area 510 of the upstream recording head 211 and the downstream recording head 212 is performed. That is, the nozzles in the overlapping nozzle area 510 of the recording head 211 and the nozzles in the overlapping nozzle area 510 of the recording head 212 are both preliminarily ejected into the head passage area 505 of the recording medium (label) based on the same ejection data. I do. As a result, the ink droplets ejected from the nozzles arranged at the same position in the X direction in the overlapping nozzle region 510 of each of the recording heads 211 and 212 land at the same position. That is, the dot 1001 formed by the ink droplets ejected from the nozzles in the overlapping nozzle region 510 is a dot formed in a state where two ink droplets overlap.

  11A and 11B are enlarged views showing the dots 1001 formed by the nozzles in the overlapping nozzle region 510 of the recording heads 211 and 212, where FIG. 11A is a plan view and FIG. 11B is a cross-sectional view. Unlike the conventional adjacent dots 701 and 702, the dot 1001 that has landed at the same location in the present case is a dot that is formed by landing an ink droplet at the same position. That is, it can be said that the dot 1001 is a dot formed by overlapping two dots 1101 and 1102 at the same position as shown in FIG. Thus, the diameter of the dot 1001 in which two dots overlap is not widened and is not conspicuous. In particular, the dots 1101 and 1102 shown in the cross-sectional view of FIG. 11B indicate dots formed by combining a recording medium (label) 401 that hardly penetrates ink and ink that hardly penetrates the recording medium. Therefore, the spread of the dot diameter is suppressed, and the ink does not penetrate into the label 401 and is fixed on the surface of the label 401. Accordingly, there is little density difference between the dot formed by only one ink droplet and the dot formed by landing two ink droplets overlapping at the same position, and the medium preliminary ejection to both head passage areas 505 The dots formed in (1) do not stand out in the recorded image. That is, even if the medium preliminary ejection is performed, the image recorded by the overlapping nozzle region 510 of both the recording head units 201 and 202 (joint region image) and the image recorded by the non-overlapping nozzle regions 511 and 512 are between the images. Density unevenness does not occur. Therefore, according to the present embodiment, it is possible to form a high-quality image while performing preliminary ejection without stopping the recording operation.

  FIG. 12 is a flowchart illustrating a control procedure of a recording operation executed by the control unit 300 in the ink jet recording apparatus according to the present embodiment.

  The control unit 300 receives data relating to recording, such as recording data transmitted from the host computer 104. In step S1202, the CPU 301 determines the conveyance speed of the recording medium in the recording operation. The conveyance speed is determined by referring to a conveyance speed set by the user or a conveyance speed setting value added to the image data. In the present embodiment, any one of three types of conveyance speeds (recording speeds) 200, 150, and 100 mm / sec can be set. In step S1203, medium preliminary ejection data having a pattern suitable for the set conveyance speed is determined. Since the period of the medium preliminary discharge of the nozzle is set in advance, it is necessary to change the pattern of the medium preliminary discharge data depending on the conveyance speed. In the present embodiment, three types of medium preliminary ejection data corresponding to each of the three types of medium transport speeds 200, 150, and 100 mm / sec that can be set are stored in the nonvolatile memory (ROM) 302.

  In step S1204, the CPU 301 expands the medium preliminary ejection data in the image memory 304. The development is performed on the medium preliminary ejection data development area provided for developing the medium preliminary ejection data in the image memory 304 as the bit map pattern data 601 as the medium preliminary ejection data determined in step S1203.

  In step S <b> 1205, the CPU 301 determines medium preliminary ejection data for the upstream recording head 201. That is, the medium preliminary ejection data in the upstream recording head passage area 503 and the area 902 corresponding to both head passage areas 505 among the preliminary ejection data developed in the image memory 304 in step S1204 is the medium of the upstream recording head 211. Preliminary ejection data.

  In step S <b> 1206, the CPU 301 determines medium preliminary ejection data for the downstream recording head 212. That is, the preliminary ejection data in the downstream recording head passage area 504 and the area 903 corresponding to both head passage areas 505 are subjected to registration adjustment of the nozzle and image connection portion corresponding to the designed recording head overlap area 505. It asks from. Of the medium preliminary ejection data expanded in the image memory 304 in step S1204, the medium preliminary ejection data in the downstream recording head passage area 504 and the area 903 corresponding to both head passage areas 505 are used as the medium of the downstream recording head 212. Preliminary ejection data. In the ink jet recording apparatus of the present embodiment, the number of nozzles corresponding to the overlapping nozzle region 510 of the designed recording head is eight. However, in the registration adjustment of the image connection portion, adjustment is performed by 2 nozzles in the direction of expanding the image connection portion, so the number of nozzles corresponding to the overlapping nozzle region 505 of the actual recording head is 10 nozzles as shown in FIG. It has become.

  In step S1207, the control unit 300 moves the recording head 201 to a position for performing a recording operation. In step S1208, the control unit 300 feeds the continuous paper 200 as a recording medium from the roll paper 200R according to the conveyance speed determined in step S1202, and conveys it in the Y direction. In step S1209, the CPU 301 determines whether or not the label 401 has reached a recordable position. This determination is made based on a detection signal from a medium front end sensor (not shown) that can detect the head of the label 401 attached to the continuous paper 200. If it is determined that the recording medium has reached the recording start position, the process proceeds to the next step 1210.

  In step S1210, since the label 401 has reached the recording start position, recording on the label 401 is performed based on the received binary image data. Furthermore, in step S1211, medium preliminary discharge is started. The medium preliminary ejection data for ejecting ink from the nozzles of the recording heads 211 and 212 in step S1205 and step S1206 and the binary image data are logically summed by a logical sum circuit (not shown) built in the head drive circuit 305. . The ink ejection of the recording head is controlled based on the logical sum data. That is, the medium preliminary ejection based on the medium preliminary ejection data is executed while performing the recording operation based on the image data.

  In step S1212, the CPU 301 determines whether to interrupt or end the recording operation. This determination is made by confirming whether or not a recording operation interruption factor such as the loss of image data or a recording operation end factor such as the end of recording of the last page has occurred. While such an interruption factor or termination factor does not occur, the CPU 302 transfers the image data to the head drive circuit 305 via the control circuit 311 and continues the recording operation based on the image data. Further, the CPU 301 transfers the medium preliminary ejection data to the head driving circuit 305 in step S1213. The transfer of the medium preliminary ejection data is continuously performed while the recording operation is being performed. When the medium preliminary ejection data 901 is exhausted, the medium preliminary ejection data 901 is transferred again from the beginning.

  Thereafter, when a printing operation end factor occurs, the CPU 301 stops the recording process (step S1214) and stops the medium preliminary ejection operation (step S1215). In step S1216, the conveyance of the roll paper 200 is stopped. Thereafter, in step S1217, the recording head 201 is moved to the standby position. Thus, a series of control operations in the ink jet recording apparatus according to the present embodiment is completed.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. Also in the second embodiment, a recording operation is performed using the same recording head as in the first embodiment. That is, a recording operation and medium preliminary ejection are performed using the recording heads 211 and 212 having the overlapping nozzle region 510 and the non-overlapping nozzle regions 511 and 512. Accordingly, the same or corresponding parts as those in the first embodiment are denoted by the same reference numerals. The second embodiment also has the configuration shown in FIGS. 1 to 3 and FIG.

  Hereinafter, the difference between the second embodiment and the first embodiment will be mainly described. As described above, in the first embodiment, an example in which all the nozzles of the overlapping nozzles of the recording heads 211 and 212 can be used for recording in the both head passage areas 510 to perform image recording is taken. explained. That is, in both the recording head passage areas 510, an image for one raster in the transport direction is recorded and the medium is preliminarily ejected using the nozzles of the recording head 211 and the recording head 212 arranged at the same position in the X direction. It was. However, in the second embodiment, each raster is formed using a single nozzle. That is, one raster can be formed using only the nozzles of one of the recording heads 211 and 212, and the nozzle of the other head that is in the same position as the nozzle in the X direction Neither the ink ejection for forming nor the medium preliminary ejection is performed.

  FIG. 13 is a diagram schematically illustrating the nozzle arrays of two recording heads that eject ink of the same color according to the second embodiment, and the dot arrangement of an image recorded by these nozzle arrays. FIG. 3 is a diagram schematically illustrating a nozzle array of a recording head and an array of dots of an image recorded by the nozzle array. As shown in the figure, also in the second embodiment, the two printhead units 201 and 202 are similar to the first embodiment in that one end portion of the nozzle row of each printhead unit overlaps in the transport direction. Are arranged to be. Ink droplets ejected from the nozzles 506 in the non-overlapping nozzle area 511 of the upstream recording head 211 land on the upstream head passage area 503 of the label 401 to form dots 501. Ink droplets ejected from the nozzles 507 in the non-overlapping nozzle area 512 of the downstream recording head 212 land on the downstream head passage area 504 of the label 401 to form dots 502.

  Further, for both head passage areas 510 of the label 401, the nozzles of the upstream recording head 211 and the nozzles of the downstream recording head 212 are alternately used in the nozzle arrangement direction. That is, as shown in FIG. 13, the image formation in both head passing areas 510 is performed by alternately arranging a raster formed only by the dots 501 and a raster formed only by the dots 502 in the nozzle arrangement direction (X direction). By forming into. In this way, by forming an image of the recording head overlapping area 505 with the plurality of recording heads 201, it is possible to reduce the image quality deterioration of the image connection portion due to the difference in the ink ejection amount of each recording head 201.

  In the second embodiment, since the nozzles in the overlapping nozzle region of each recording head are used every other nozzle in the nozzle arrangement direction, nozzles that do not eject ink for image formation, that is, image formation. There will be nozzles 506 and 507 which do not contribute. In the second embodiment, the following medium preliminary ejection is performed on both head passage regions (image connecting portions) of the label 401 in the overlapping nozzle region 510 of both recording heads 211 and 212.

  FIG. 14 is a schematic diagram for explaining medium preliminary ejection performed on both head passage areas 505 by the overlapping nozzle region 510 of the recording heads 211 and 212 in the second embodiment. Also in the second embodiment, the medium preliminary ejection of the upstream recording head 211 and the downstream recording head 212 is performed based on the medium preliminary ejection data 901. That is, in the non-overlapping nozzle area 511 of the upstream recording head 211, medium preliminary ejection is performed according to data corresponding to the upstream recording head passage area 511 from among the medium preliminary ejection data 901, and the dot 701 is placed in the passage area 511. Only formed. Further, in the non-overlapping nozzle area 512 of the downstream recording head 212, medium preliminary ejection is performed according to data corresponding to the downstream recording head passage area 512 from the medium preliminary ejection data 901, and dots 702 are placed in the passage area 512. Is formed. Further, in the overlapping nozzle area 510 of each of the recording heads 211 and 212, the medium preliminary discharge is performed according to the data in the area 904 from the medium preliminary discharge data 901. In other words, the same data (data in the area 904) is supplied to the head drive circuit 305 for both the medium preliminary ejection in the overlapping nozzle area 510 of the recording head 211 and the medium preliminary ejection in the overlapping nozzle area 510 of the recording head 212. Is done. However, among the nozzles in the overlapping nozzle region 510 of the recording heads 211 and 212, the nozzles 506 and 507 that do not contribute to the image formation as described above do not deteriorate the image quality even if the paper surface preliminary ejection is not performed. Therefore, medium preliminary ejection is not performed. For this reason, the dots 701 and 702 formed in both the head passage regions 505 are not adjacent to each other in the nozzle arrangement direction and the transport direction and are arranged at equal intervals. In all the areas 503, 504, and 505, the dots to be formed are all formed by one ink droplet. For this reason, all the dots to be formed have substantially the same density and dot diameter, the dots formed in the both head passage areas 505 by the medium preliminary discharge become inconspicuous, and the image quality deterioration due to the medium preliminary discharge is greatly reduced. The

  In the recording method in which rasters parallel to the conveyance direction are alternately formed in different nozzle heads in the overlapping nozzle region 510 as in the second embodiment, the conventional medium preliminary ejection data shown in FIG. 6 is used. Then, dots are formed as shown in FIG. In this case, medium preliminary ejection data that is different between the overlapping nozzle area 510 of the upstream recording head 211 and the overlapping nozzle area 510 of the downstream recording head 212 is supplied to the drive circuit 305. As a result, the dots 701 and 702 formed in the recording head overlap area 505 by the upstream recording head 201 and the downstream recording head 201 are adjacent to each other in the nozzle row direction. When the dots 701 and 702 are formed adjacent to each other, they are recognized as one large dot and are conspicuous, so that the image quality is greatly reduced. Therefore, it is impossible to form a high-quality image as in the second embodiment of the present invention.

  In the above description, the case where an image connection portion is recorded by the recording heads 211 and 212 that discharge ink of a certain color in the recording head units 201 and 202 has been described. However, the other three-color recording heads 211 and 212 can similarly perform image recording processing and medium preliminary ejection processing.

(Other embodiments)
In each of the above-described embodiments, the case where the two recording heads 211 and 212 are arranged so that their nozzle rows overlap in the transport direction is illustrated, but three or more recording heads may be arranged. In this case, the nozzle arrays of the respective print heads are arranged so as to overlap with a part of the adjacent nozzle arrays in the transport direction in order, and the same nozzles are reserved in the overlap nozzle area of each print head. What is necessary is just to supply discharge data.

  In the above embodiment, the image is recorded on the label attached to the continuous paper fed out from the roll paper. However, the present invention is not limited to this, and the image is recorded on the cut paper. The present invention is also effective for such a case.

DESCRIPTION OF SYMBOLS 100 Inkjet recording apparatus 200 Continuous paper 203 Conveyance roller 204 Conveyance belt 510 Overlapping nozzle area (overlapping part)
511, 512 Non-overlapping nozzle area 211 Upstream recording head 212 Downstream recording head 300 Control unit 301 CPU
401 Label 505 Both-head passing area 701 Dots formed by medium preliminary ejection of upstream recording head 702 Dots formed by medium preliminary ejection of downstream recording head 901 Preliminary ejection data 904 Preliminary ejection data corresponding to overlapping nozzle area Middle area 903 Area in the preliminary ejection data corresponding to the upstream recording head 902 Area in the preliminary ejection data corresponding to the downstream recording head 1001 dots

Claims (5)

Conveying means for conveying the recording medium along a certain conveying direction, and at least two nozzle rows in which a plurality of nozzles for ejecting ink of the same color are arranged are arranged along a direction intersecting the conveying direction, And an ink jet recording apparatus that performs recording by ejecting ink from the recording head, the recording head having an overlapping portion in which the end portions of adjacent nozzle rows overlap each other in the transport direction,
A medium preliminary ejection means for performing medium preliminary ejection for ejecting ink that does not contribute to image recording from the recording head to the recording medium based on preliminary ejection data;
The ink jet recording apparatus, wherein the medium preliminary ejection unit ejects ink from nozzles in nozzle rows located in the same overlapping portion based on the same medium preliminary ejection data. All nozzles in the overlap are used for image recording,
The inkjet recording apparatus according to claim 1, wherein the medium preliminary discharge unit performs medium preliminary discharge for all nozzles in the overlapping portion according to the same preliminary discharge data. Using the nozzles in the overlapping portion of each of the adjacent nozzle rows, it is possible to form the same raster parallel to the transport direction,
The inkjet recording apparatus according to claim 1, wherein the medium preliminary discharge unit performs medium preliminary discharge for all nozzles in the overlapping portion according to the same preliminary discharge data. Among the adjacent nozzle rows, the nozzles in the overlapping portion of one nozzle row and the nozzles in the overlapping portion of the other nozzle row can form different rasters,
The inkjet recording apparatus according to claim 1, wherein the medium preliminary discharge unit performs medium preliminary discharge only on the nozzles forming the raster among the nozzles in the overlapping portion according to the same preliminary discharge data. Conveying means for conveying the recording medium along a certain conveying direction, and at least two nozzle rows in which a plurality of nozzles for ejecting ink of the same color are arranged are arranged along a direction intersecting the conveying direction, And an ink jet recording method for performing recording by ejecting ink from the recording head, the recording head having an overlapping portion in which the end portions of adjacent nozzle rows overlap each other in the transport direction,
A medium preliminary ejection step for performing medium preliminary ejection for ejecting ink that does not contribute to image recording from the recording head to the recording medium based on preliminary ejection data;
In the ink jet recording method, the medium preliminary ejection step performs ejection of ink from nozzles in nozzle rows located in the same overlapping portion based on the same medium preliminary ejection data.