JP2013091207A - Inkjet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet recording device which suppresses a change in a distance between a recording head and a recording medium due to the recording at the end of the recoding medium in recording.SOLUTION: The inkjet recording device includes a first recording head and a second recording head so that a plurality of ejection ports forming ejection port rows formed with the recording heads are divided into two along the arrangement direction where the ejection port rows are arranged depending on where the ejection ports are formed. Regarding the first recording head which is more earlier used when the recording is performed at the end of the recording medium in a conveyance direction out of the first recording head and the second recording head, an ink ejection amount by ink ejection per unit area of the recording medium is reduced. An ink ejection amount by ink ejection per unit area of the recording medium from the second recording head which is subsequently used is increased.

Description

  The present invention relates to an ink jet recording apparatus that performs recording by ejecting ink onto a recording medium, and particularly suppresses a change in the distance between the recording head and the recording medium due to deformation of the recording medium due to recording at the end of the recording medium. The present invention relates to an ink jet recording apparatus in which recording control is performed.

  In an ink jet recording apparatus, recording is performed by ejecting ink droplets from a recording head onto a recording medium. At this time, in the portion of the recording medium where the ink is ejected, the fiber layer expands as the ink penetrates into the fiber layer. For this reason, the recording medium may be curved or deformed to wave. As a result, the distance between the surface of the recording head where the ejection opening is formed and the recording surface of the recording medium may not be constant. If the deformation of the recording medium becomes large, the recording head and the recording medium may come into contact with each other. In particular, in an ink jet recording apparatus, a plurality of recording heads may be lengthened by joining a plurality of recording heads in the transport direction. In an ink jet recording apparatus in which the recording head is lengthened, a recordable area is increased by one scan of the recording head. For this reason, depending on the recording data when recording is performed, the amount of ink applied to the recording medium increases, and the amount of ink permeating into the recording medium increases, so that the deformation of the recording medium may increase. . This increases the possibility that the recording medium and the recording head come into contact.

  In order to avoid contact between the recording head and the recording medium, for example, Patent Document 1 discloses that the recording head on the downstream side in the conveyance direction of the recording medium is positioned farther from the recording medium than the recording head on the upstream side. An arranged ink jet recording apparatus has been proposed. By arranging the recording head in this way, the recording medium is prevented from coming into contact with the recording head even if the recording medium is deformed by the ink from the upstream recording head being driven into the recording medium. .

JP 2008-195060 A

  However, in the ink jet recording apparatus disclosed in Patent Document 1, the distance (inter-paper distance) between the recording head and the recording medium differs between the upstream recording head and the downstream recording head. Therefore, there is a difference in ink droplet landing accuracy between the upstream recording head and the downstream recording head. If the ink droplet landing accuracy is lowered only for ink ejection from a part of the ejection ports of the recording head, unevenness or streaks may occur in the recorded image, and the image quality may be degraded.

  Accordingly, in view of the above circumstances, the present invention provides an ink jet recording apparatus in which a change in the distance between a recording head and a recording medium is suppressed by recording at the end of the recording medium during recording. For the purpose.

  The present invention has a recording head in which ejection ports for ejecting ink are arranged to form an ejection port array, and the recording head crosses a conveyance direction in which the recording medium is conveyed while conveying the recording medium. An ink jet recording apparatus that performs recording by ejecting ink onto a recording medium while performing scanning in a scanning direction, and the recording head performs recording by scanning a predetermined recording area a plurality of times. A plurality of discharge ports forming the discharge port array formed in the head are divided into two discharge port groups along the arrangement direction in which the discharge port columns are arranged according to the position where the discharge ports are formed. Ink ejection amount per unit area of the recording medium due to ink ejection from the first ejection port group that is used first when recording is performed on the end of the recording medium in the transport direction in the ejection port group But later used Second to be smaller than the amount of ink discharged per unit area of the recording medium by ink ejection from the ejection port group that, and having a first control means for controlling the recording.

  According to the present invention, it is possible to suppress the change in the distance between the recording head and the recording medium due to the deformation of the recording medium during recording on the end of the recording medium, so that the quality of the recorded image is reduced. can do.

FIG. 2 is a plan view schematically showing a configuration of a main part of the ink jet recording apparatus according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing a peripheral portion of a recording head in the ink jet recording apparatus of FIG. 1. FIG. 3 is a plan view schematically showing the recording head of FIG. 2 as viewed from the recording medium side. FIG. 2 is a block diagram illustrating a configuration of a control system in the ink jet recording apparatus of FIG. 1. 3 is a flowchart illustrating a flow of recording control when recording is performed on an end portion of a recording medium by the ink jet recording apparatus of FIG. 1. FIG. 4 is an explanatory diagram for describing an area of an ejection port used when recording on an end portion of a recording medium in the recording head of FIG. 3. FIG. 2 is an explanatory diagram for explaining a recording rate for each pass by a region of each recording head when recording is performed on an end portion of a recording medium by the ink jet recording apparatus of FIG. 1. FIG. 2 is an explanatory diagram for explaining a positional relationship between a recording head region and a recording medium used for each pass when recording is performed on the leading end portion of the recording medium by the ink jet recording apparatus of FIG. 1. is there. Explanatory drawing for demonstrating the positional relationship between the area | region of the recording head used for each path | pass, and a recording medium when recording to the rear-end part of a recording medium is performed by the inkjet recording device of FIG. It is. 6 is a flowchart illustrating a flow of recording control when recording is performed on an end portion of a recording medium by an ink jet recording apparatus according to a second embodiment of the present invention.

Embodiments of the present invention will be described below with reference to the drawings.
(First embodiment)
First, the overall configuration of the ink jet recording apparatus according to the first embodiment of the present invention will be described.

  FIG. 1 is a plan view schematically showing main parts of the ink jet recording apparatus 100 according to the first embodiment. FIG. 2 is a cross-sectional view schematically showing the periphery of the recording heads 3 and 10 of the inkjet recording apparatus 100 according to the first embodiment. The ink jet recording apparatus 100 performs recording by discharging ink from the recording heads 3 and 10 to a recording medium.

  The transport unit 1 includes a transport roller 11 that is rotationally driven, and a driven roller 12 that rotates following the transport roller 11. The recording medium is conveyed along the conveying direction by rotating the conveying roller 11 while the recording medium is sandwiched between the conveying roller 11 and the driven roller 12. The transport roller 11 is driven by a transport motor 102.

  The inkjet recording apparatus 100 is loaded with a roll paper 4 as a recording medium. When an image is recorded on the roll paper by the recording head, the inkjet recording apparatus 100 can cut the roll paper there. Therefore, the length of the recording medium can be set to a desired length by adjusting the timing of cutting the roll paper.

  The recording heads 3 and 10 are mounted on the carriage 2, and the recording heads 3 and 10 scan as the carriage 2 moves. In the present embodiment, two recording heads 3 and 10 are arranged in the carriage 2 in the conveyance direction of the recording medium. In the first recording head (first ejection port group) 3, ejection port arrays are formed by arranging ejection ports for ejecting ink. Further, the second recording head (second ejection port group) 10 has ejection ports arranged in the same direction as the arrangement direction in which the ejection port arrays formed in the first recording head 3 are arranged. An exit row is formed. While transporting the recording medium, the first recording head 3 and the second recording head 10 eject ink onto the recording medium while scanning in the main scanning direction intersecting the transport direction in which the recording medium is transported. Recording is performed. In the present embodiment, the first recording head 3 and the second recording head 10 perform recording by scanning a predetermined recording area a plurality of times. That is, the ink jet recording apparatus of the present embodiment is a multipass ink jet recording apparatus. In the present embodiment, the plurality of ejection ports forming the ejection port array formed in the recording heads 3 and 10 are divided into two ejection port groups along the arrangement direction in which the ejection port arrays are arranged. Each of these two ejection port groups functions as a recording head, and performs recording on a recording medium by ejecting ink as the first recording head 3 and the second recording head 10. In the present embodiment, the recording heads 3 and 10 perform recording by scanning respective predetermined recording areas. The ejection port arrays in the two recording heads 3 and 10 are connected in the conveyance direction of the recording medium while being shifted in the main scanning direction. The ejection port arrays of the two recording heads 3 and 10 are arranged such that the pitch between the ejection ports of the connecting portions where the two recording heads 3 and 10 are adjacent is the same length as the pitch of the recording heads 3 and 10. Are arranged.

  In the present embodiment, the recording heads 3 and 10 are formed such that the first recording head 3 and the second recording head 10 have the same number of ejection openings. Accordingly, the ejection ports forming the ejection port array are divided into two equal parts along the arrangement direction of the ejection port arrays in each of the recording heads 3 and 10. In the present embodiment, the first recording head 3 and the second recording head 10 are recording heads having the same characteristics such as the number, arrangement, and pitch length of the discharge ports.

  In the present embodiment, the carriage 2 has the first recording head 3 mounted on the upstream side in the recording medium conveyance direction, and the second recording head 10 mounted on the downstream side. The carriage 2 is supported so as to be movable along a guide shaft 5 disposed along the X direction. An endless belt 6 that moves substantially parallel to the guide shaft 5 is attached to the carriage 2. When the carriage moves in the main scanning direction, the endless belt 6 reciprocates by the driving force of the carriage motor, and the carriage 2 reciprocates as the endless belt moves.

  A platen 7 for supporting the recording medium S is provided at a position corresponding to the recording area in the inkjet recording apparatus 100 so as to face the ink ejection surface of the recording head. Below the platen 7 (Z direction), a fan 8 and a fan motor for driving the fan 8 are attached as a suction device for attracting the recording medium S to the platen 7.

  FIG. 3 is a plan view of the ejection surface formed with ejection ports in the recording head mounted on the carriage as viewed from the recording medium. The first recording head 3 and the second recording head 10 are mounted on the carriage 2 with a predetermined shift in the X direction and the Y direction, respectively. Each of the first recording head 3 and the second recording head 10 has ejection port arrays 9K, 9C, and 9M that eject black (K), cyan (C), magenta (M), and yellow (Y) inks. 9Y. The ejection ports formed in each recording head are arranged so as to be aligned with a constant pitch P in the Y direction. The pitch of the ejection ports in the Y direction is 1200 dpi (dots / inch), and 1280 ejection ports are arranged in each ejection port array. Further, as described above, the discharge port pitch P ′ at the connecting portion in the Y direction between the first recording head 3 and the second recording head 10 is equal to the pitch P between the discharge ports in each discharge port array ( P = P ′).

  In the ink jet recording apparatus 100 of this embodiment, each of the ink flow paths in the recording heads 3 and 10 is provided with a heating element (electrothermal converter). By selectively energizing the heating element and generating thermal energy from the heating element, the ink in the ink flow path is heated and foamed by film boiling, and ink droplets are ejected from the ejection port by the foaming energy at that time. Discharged. The ink jet recording apparatus 100 according to the present embodiment is a serial scan type ink jet recording apparatus in which recording is performed while the recording heads 3 and 10 scan in a direction crossing the conveyance direction of the recording medium. The ink jet recording apparatus 100 according to the present embodiment intermittently transports the recording medium S in the Y direction by the transport unit 1 and moves the recording head in the direction (X direction) orthogonal to the transport direction (Y direction) of the recording medium. Move back and forth. In the ink jet recording apparatus 100, as described above, the carriage 2 is guided by the guide shaft 5 so as to be movable in the main scanning direction. The carriage 2 is reciprocated in the main scanning direction while being guided by the guide shaft 5 by the carriage motor 103 and the endless belt 6 that transmits the driving force. The ink jet recording apparatus 100 moves the recording heads 3 and 10 in the main scanning direction, ejects ink toward the print area of the recording medium, and moves the recording medium in the sub scanning direction by a distance corresponding to the recording width. And the transfer operation of transferring to. By performing the recording operation and the conveying operation mutually, images are sequentially recorded on the recording medium. The recording head according to the present embodiment employs a system in which film boiling is generated in the ink by a heating element to cause foaming to eject ink droplets, but the present invention is not limited to this. A recording head that deforms the piezoelectric element and thereby discharges liquid inside the recording head may be applied to the ink jet recording apparatus, and other types of recording heads may be applied to the ink jet recording apparatus of the present invention. Also good.

  FIG. 4 is a block diagram for explaining the configuration of the control system of the inkjet recording apparatus 100 according to this embodiment. The inkjet recording apparatus 100 is connected to a host PC 200 via an I / F (interface) 300. Various data and control signals transmitted from the host PC 200 are input to the recording control unit (CPU) 101 of the inkjet recording apparatus 100. The recording control unit 101 executes various processes according to the input control signal and the like. The conveyance motor 102 rotates the conveyance roller 11 in response to a signal from the motor driver 104. The carriage motor 103 reciprocates the carriage 2 by the motor driver 105. A plurality of head drivers 106 provided according to the number of recording heads drive the recording heads to perform ink ejection control. Furthermore, the ink jet recording apparatus 100 is provided with various sensors such as a temperature / humidity sensor 107 and a head Z position sensor 108, and these pieces of information are input to the recording control unit 101.

  Next, the recording operation of the ink jet recording apparatus 100 in the present embodiment will be described. The roll paper 4 is guided to the transport unit 1 through the transport path, and then sent out from the transport unit 1 to the platen 7. When the recording medium reaches the platen 7, the recording medium is adsorbed on the platen 7 by driving the fan 8 below the platen 7. The recording medium S adsorbed on the platen 7 is ejected with ink droplets from the recording heads 3 and 10 to form an image. In the present embodiment, while the recording medium S is attracted to the platen 7, the recording operation and a plurality of transport operations at a predetermined pitch are repeated to perform recording. At this time, the ejection ports of the ejection port array formed in each of the recording heads 3 and 10 are divided into a plurality of ejection ports, and recording is performed by ejecting ink droplets for each of the divided blocks. Usually, in each of the recording heads 3 and 10, the ejection ports to be used are equally divided to form a block having a plurality of ejection ports, and ink droplets are ejected from the ejection ports for each of the divided blocks. As described above, by performing the division recording for each block, it is possible to avoid streaks and density unevenness due to the pitch error of the discharge ports in the recorded image.

  When there is a recording instruction, the roll paper 4 is guided to the platen 7 and conveyed in the sub-scanning direction at a predetermined pitch while being attracted by the platen 7. Then, ink droplets are ejected from the ejection port of the recording head to the recording medium S based on the image data. When the first pass is completed, the recording medium S is conveyed at a predetermined pitch while being in close contact with the platen 7, and ink droplets are again ejected from the ejection ports of the recording head based on the image data. By repeating the above operation for the designated number of passes, the entire recorded image is formed on the recording medium S.

  In the recording control of the present embodiment, the recording head is divided into a plurality of areas depending on the positions where the plurality of ejection openings formed in the recording head are formed, and the predetermined area of the recording medium is separated from the ejection openings in the respective areas. Divided recording in which ink is discharged over a plurality of times is performed. In the case where division recording is performed in this way, when an image is formed on the leading end portion and the trailing end portion of the recording medium S, the ink discharge amount discharged from the first recording head 3 is discharged from the second recording head 10. Recording is controlled so as to be smaller than the ink discharge amount. In other words, in the present embodiment, the ink discharge amount per unit area of the recording medium by the ink discharge from the first recording head 3 used first out of the two recording heads 3 and 10 is used later. Recording is controlled to be smaller than that of the second recording head 10. In the present embodiment, the recording control unit 101 functions as a control unit (first control unit) that controls recording by the inkjet recording apparatus 100 when recording is performed on an end of the recording medium in the transport direction. Since the recording is controlled in this way, as described later, the above-described control is carried out at the leading end portion and the trailing end portion of the recording medium which are easily deformed, so that the recording medium is used by the ink ejected from the first recording head 3. S is prevented from being deformed.

  Hereinafter, the control flow of the recording control of the present embodiment will be described according to the flowchart. FIG. 5 is a control flow of the inkjet recording apparatus 100 according to the present embodiment. When recording is started, in step 401, the paper type selected by the user is determined. In this embodiment, control is performed for plain paper that is largely deformed by absorbing ink and relatively thin coated paper, and when other types of recording media are used, the recording control of the present invention is A normal recording operation is performed without being performed. However, the recording medium on which the recording control of the present invention is performed is not limited to plain paper or thin coated paper. The recording control of the present invention may also be performed when other recording media are used.

  If the paper type of the non-target recording medium is used in step 401, the control flow proceeds to step 403, and the recording rates of the first recording head 3 and the second recording head 10 are set uniformly. The recorded mask is selected and recording is performed. Here, the recording rate refers to the amount of ink ejected onto the recording medium per unit area of the recording medium. If the paper type recording medium to be subjected to the recording control of this embodiment is selected in step 401, the flow proceeds to step 402, and the number of recording passes (N) selected by the user is determined.

  If it is determined in step 402 that the number of passes N is N = 3 or less, it is determined that the number of passes is outside the scope of the present invention, and the flow proceeds to step 403 where the first print head 3 and the second A mask in which the recording rate of the recording head 10 is set to be uniform is selected and recording is performed. Therefore, the flow moves to step 417, and recording is performed through a mask using a mask with a uniform recording rate through all passes. If it is determined in step 402 that the number of passes N is N = 4 or more, the process proceeds to step 404 where the recording rates of the first recording head 3 and the second recording head 10 are set to be different. Recording is started from the leading edge of the sheet by selecting a non-uniform mask.

  Here, recording on the leading end portion of the recording medium by the ink jet recording apparatus 100 will be described. In step 405, recording control is started for recording on the tip. Next, in step 406, the recording data is read for each pass, and the recording for that pass is performed. At this time, the number of passes n is from 1 pass to N / 2 passes (using the first recording head), and the ink discharge amount is from (N / 2 + 1) pass to N pass (using the second print head). Control is performed so as to be smaller than the ink discharge amount. Therefore, control is performed so that the ink consumption from the 1st pass to the N / 2th pass is smaller than the ink consumption from the (N / 2 + 1) th pass to the Nth pass. When the recording process for one pass is completed, the recording of the leading end is completed (step 407). Subsequently, the process proceeds to step 408, and the recording head 3 is shifted in the sub scanning direction by the recording medium being conveyed in the conveying direction.

  Subsequently, the flow moves to step 409, a uniform mask in which the recording ratios of the first recording head 3 and the second recording head 10 are set to be uniform is selected, and the center other than both ends of the recording medium in the transport direction is selected. Execute recording to the department. Subsequently, in step 410, recording control is started for recording in the central portion. Next, in step 411, the recording data for each pass in the central portion is read, and recording is performed for each pass in which the recording data is read. The recording process for each pass is repeated for the number of passes in the central portion, and when the recording in the central portion is completed, the recording medium is transported in the transport direction, thereby shifting the recording head in the sub-scanning direction. Thus far, an image from the front end portion of the recording medium to the front of the rear end portion is formed.

  Here, the front end portion of the recording medium is an end portion on the downstream side in the transport direction of the recording medium, and a portion in a range where the recording heads 3 and 10 can perform recording in one scan. Say it. Further, the rear end portion of the recording medium is an end portion on the upstream side in the transport direction of the recording medium, and a portion in a range where the recording heads 3 and 10 can perform recording by one scanning. Say it.

  In the present embodiment, if the number of scans in the forward direction and the number of scans in the backward direction of the recording heads 3 and 10 that perform reciprocal scanning are different, the density due to the recording is different, and the quality of the recorded image may be reduced. Therefore, in general, an even value is often used for the number of passes N. For this reason, N / 2 paths and (N / 2 + 1) paths are usually integer values. However, an odd number may be used as the number of passes N. In such a case, the N / 2 path and (N / 2 + 1) path are not integers. Therefore, in that case, the digits below the decimal point may be rounded up or rounded down.

  Subsequently, the flow moves to step 412, the recording medium is transported, and the recording area on the recording medium by the recording head 3 is relatively shifted in the transport direction. Subsequently, the flow proceeds to step 413, the non-uniform mask set so that the recording rates of the first recording head 3 and the second recording head 10 are different is selected, and recording of the trailing edge of the sheet is started. (Step 414). Subsequently, in step 415, recording control is started for recording on the rear end.

  Next, in step 416, the recording data is read for each pass, and recording for each read pass is performed. At this time, the ink discharge amount from the first pass to the N / 2th pass (using the first recording head) is the ink discharge amount from the (N / 2 + 1) th pass to the Nth pass (using the second printhead). Control is performed so as to be less than the amount. When the recording process for one pass (nth pass) is completed, the next pass (n + 1th pass) is recorded. By repeating this for N passes, the recording on the leading end of the recording medium is completed. When recording on the leading end of the recording medium is completed, recording is performed on the central portion of the recording medium other than the leading end and the trailing end of the recording medium. In recording on the central portion of the recording medium, recording is performed using a mask in which pixels to be recorded are evenly distributed for each pass. When the recording on the central portion is finished, the recording on the rear end portion of the recording medium is performed next.

  In the recording on the rear end portion of the recording medium, the ink consumption amount from the first pass to the N / 2 pass (using the first recording head) is (N / 2 + 1) passes in the same manner as the recording on the front end portion. Control is performed so that the ink consumption is less than the first to Nth passes (using the second recording head). When the recording of the rear end portion of the recording medium is completed, the entire image is recorded and the recording is completed. In this embodiment, the control is executed for the number of passes N = 4 or more, but the present invention is not limited to this, and the control may be executed with N = 2, 3.

  As described above, in the present embodiment, the amount of ink discharged from the first recording head 3 is smaller than the amount of ink discharged from the second recording head 10 in recording on the leading and trailing ends of the recording medium that are easily deformed. To form an image. However, the present invention is not limited to this, and the above-described recording control may be performed only on either the front end portion or the rear end portion. That is, by limiting the application range of the non-uniform mask to the leading edge and the trailing edge of the sheet, it is possible to prevent a difference in the lifespan between the first recording head 3 and the second recording head 10. Furthermore, the probability of image unevenness due to the use of a non-uniform mask is reduced.

  Next, an actual image forming procedure will be described by taking four-pass divided recording (N = 4) in which recording in a predetermined area is performed by four-pass recording as an example. FIG. 6 is a plan view showing discharge port division in the case of 4-pass division printing. FIG. 7 shows print data and the entire image of the nth pass in the case of 4-pass division printing. The ejection port arrays of the first recording head 3 and the second recording head 10 are equally divided so that the ejection port length becomes 4 passes (3a = 3b = 10a = 10b). An image 500 is an entire image that has been recorded at a recording rate of 100%. As a procedure for forming the entire image, first, an image 500a having a recording rate of 10% is recorded in the first pass. Next, the recording head is moved by one pass in the sub-scanning direction, and an image 500b with a recording rate of 20% in the second pass is recorded. Up to this point, recording by the first recording head 3 has been performed, and 30% of the entire image 500 has been recorded. Next, the recording head is moved by one pass in the sub-scanning direction, and an image 500c with a recording rate of 40% in the third pass is recorded. Further, the recording head is moved by one pass to record an image 500d with a recording rate of 30% in the fourth pass. As a result, an entire image is formed by 4-pass division recording. That is, the first recording head 3 forms an image with a recording rate of 30%, and the second recording head 10 forms an image with a recording rate of 70%. In this embodiment, the image recording rate is set as described above. However, the present invention is not limited to this, and the ink of the first recording head 3 consumed until the entire image is formed at the end of the recording medium. It is sufficient that the ejection amount is smaller than the ink ejection amount of the second recording head 10.

  A case where 4-pass division recording (N = 4) is performed in recording on the leading end of the recording medium will be described in more detail with reference to FIG. Here, the recording operation will be described by paying attention to the area A of the most distal portion in the transport direction at the leading end of the recording medium. When recording is performed on the leading end portion of the recording medium, first, as shown in FIG. 8A, the recording heads 3 and 10 are arranged at positions close to the leading end portion of the recording medium. From there, as shown in FIG. 8B, the recording medium is conveyed in the conveying direction by a length corresponding to half the length of the first recording head 3. When the recording medium is thus transported to the recording heads 3 and 10, the recording heads 3 and 10 move from the upstream side of the first recording head 3 in the transport direction of the recording medium while moving in the main scanning direction. Ink is ejected toward the recording medium, and recording is performed by the first recording head 3. At this time, recording is performed only on the area A by using the discharge ports corresponding to the upstream half area of the first recording head 3. In this embodiment, since the recording here is the first pass recording for the area A, the recording is performed so that the recording rate in this recording is 10%.

  Therefore, when the recording corresponding to half the length of the first recording head 3 is performed, the recording medium is transported in the transport direction from the recording medium corresponding to the half length of the first recording head 3. . As shown in FIG. 8C, the positional relationship between the recording heads 3 and 10 and the recording medium is such that the position of the leading end of the recording medium is located at a portion corresponding to the downstream leading end of the first recording head 3. Thus, recording is performed on the area A on the downstream side in the transport direction of the first recording head 3. At this time, while the recording heads 3 and 10 move in the main scanning direction, ink is discharged from the downstream portion of the recording head 3 to the recording medium, and recording is performed by the first recording head 3. Since the recording here is the second-pass recording for the area A, the recording is performed so that the recording rate in the recording here is 20%.

  When the recording on the area A by the downstream portion of the first recording head 3 is completed, the recording medium is conveyed in the conveying direction by an amount corresponding to half the length of the second recording head 10. As shown in FIG. 8D, when the positional relationship between the recording heads 3 and 10 and the recording medium is such that the leading end of the recording medium is positioned at a portion corresponding to the central portion of the second recording head 10. Recording is performed on the area A on the upstream side in the transport direction of the second recording head 10. Since the recording here is the third pass recording for the area A, the recording is performed so that the recording rate in this recording is 40%.

  When the recording on the area A by the upstream portion of the second recording head 10 is completed, the recording medium is conveyed in the conveying direction by an amount corresponding to half the length of the second recording head 10. As shown in FIG. 8E, when the leading end of the recording medium is located at a portion corresponding to the downstream end of the second recording head 10, the conveyance direction of the second recording head 10 with respect to the region A Recording is performed by the downstream portion. Since the recording here is the fourth-pass recording for the area A, the recording is performed so that the recording rate in the recording here is 30%.

  In this way, the recording rate 10% for the first pass, the recording rate 20% for the second pass, the recording rate 40% for the third pass, and the fourth pass for the region A located at the most leading end side in the leading end of the recording medium. Recording is performed with an eye recording rate of 30%. As described above, when recording is performed on the leading end in the conveyance direction of the recording medium, the ink discharge amount per unit area of the recording medium due to the ink discharge from the first recording head 3 used earlier is Recording is controlled to be smaller than that from the second recording head 10 used. That is, when recording in a predetermined recording area is performed by four scans, recording is performed by ink ejection by the first recording head 3 in the first to second scans, and the third to fourth times. Recording is performed by ink ejection by the second recording head 10 in the scanning up to. At this time, the printing is controlled so that the amount of ink ejected in the first to second scans is smaller than the amount of ink ejected in the third to fourth scans. As described above, in the present embodiment, when a predetermined recording area is recorded in N scans, ink is ejected by the first recording head 3 in the first to (N / 2) th scanning. Done. Further, ink is ejected by the second recording head 10 in the (N / 2 + 1) th to Nth scans. The recording is performed so that the amount of ink ejected in the first to (N / 2) th scanning is smaller than the amount of ink ejected in the (N / 2 + 1) th to Nth scanning. Is controlled. In the present embodiment, the recording control unit 101 functions as a control unit (first control unit, second control unit) that controls recording.

  The same recording as that at the front end of the recording medium is performed on the rear end of the recording medium. Recording on the rear end of the recording medium will be described with reference to FIG. When recording is performed on the rear end of the recording medium, first, as shown in FIG. 9A, the upstream portion of the first recording head 3 is positioned at a position corresponding to the rear end of the recording medium. Be placed. From there, the recording medium is conveyed in the conveying direction by a length corresponding to half the length of the first recording head 3, as shown in FIG. When the recording medium is transported to the recording heads 3 and 10 in this way, the recording heads 3 and 10 move from the upstream portion of the first recording head 3 in the transport direction to the recording medium while moving in the main scanning direction. Ink is ejected toward the head and recording is performed by the first recording head 3. At this time, the ejection ports corresponding to the upstream half area of the first recording head 3 are used, and recording is performed only on the area B located at the rearmost end. In the present embodiment, since the recording here is the first pass recording for the region B, the recording is performed so that the recording rate in this recording is 10%.

  Therefore, when the recording corresponding to half the length of the first recording head 3 is performed, the recording medium is transported in the transport direction from the recording medium corresponding to the half length of the first recording head 3. . When the positional relationship between the recording heads 3 and 10 and the recording medium is as shown in FIG. 9B, the rear end position of the recording medium is positioned at a portion corresponding to the central portion of the first recording head 10. Recording is performed on the area B on the downstream side in the transport direction of the first recording head 3. At this time, while the recording heads 3 and 10 move in the main scanning direction, ink is ejected from the downstream portion of the first recording head 3 to the recording medium, and recording is performed by the first recording head 3. Since the recording here is the second pass recording for the region B, the recording is performed so that the recording rate in the recording here is 20%.

  When the recording in the area B by the downstream portion of the first recording head 3 is completed, the recording medium is conveyed in the conveying direction by an amount corresponding to half the length of the second recording head 10. As shown in FIG. 9C, in the positional relationship between the recording heads 3 and 10 and the recording medium, the rear end portion of the recording medium is positioned at a portion corresponding to the upstream end portion of the second recording head 10. Relationship. When the positional relationship between the recording heads 3 and 10 and the recording medium is such a positional relationship, recording is performed by the portion of the second recording head 10 on the upstream side in the transport direction with respect to the region B. Since the recording here is the third pass recording for the area B, the recording is performed so that the recording rate in the recording here is 40%.

  When the recording on the area B by the upstream portion of the second recording head 10 is completed, the recording medium is conveyed in the conveying direction by an amount corresponding to half the length of the second recording head 10. As shown in FIG. 9D, when the rear end portion of the recording medium is located at a portion corresponding to the transport walking center portion of the second recording head 10, the transport in the second recording head 10 with respect to the region B is performed. Recording is performed by a portion on the downstream side in the direction. Since the recording here is the fourth pass recording for the region B, the recording is performed so that the recording rate in the recording here is 30%.

  When the recording by the second recording head 10 is finished, the recording medium passes through the position corresponding to the recording heads 3 and 10 as shown in FIG. . Thereby, the recording to the recording area B by the recording heads 3 and 10 is finished, and the recording to the recording medium is finished.

  Here, among the front end portions of the recording medium that can be recorded by the recording heads 3 and 10 by one scan, the most rear end region A and the rearmost end region among the rear end portions that can be recorded by one scan. B is described. However, in the present embodiment, among the leading end portion of the recording medium that can be recorded by one scan on the recording medium, recording is performed on the portion other than the most distal end region A by the recording control of the present invention. That is, recording is performed on a portion other than the region A on the most distal end side of the recording medium that can be recorded by one scanning, using a mask whose recording rate changes with each scanning. Further, among the rear end portion of the recording medium that can be recorded by one scanning on the recording medium, recording is performed on the portion other than the region B on the most rear end side by the recording control of the present invention. In other words, among the rear end portion of the recording medium that can be recorded by one scan, the portion other than the region B on the most rear end side is used for recording by using a mask whose recording rate changes for each scan.

  Of the leading end portion of the recording medium that can be recorded by one scan, portions other than the region A on the most distal side are sequentially recorded after the region A is recorded. When recording is performed by four-pass recording as in the present embodiment, recording is performed by four scans on the front end portion of the recording medium that can be recorded by one scan. Further, among the rear end portion of the recording medium that can be recorded by one scanning, the portions other than the region B on the most rear end side are sequentially recorded before the recording to the region B is performed. .

  As described above, in the present embodiment, when divided recording is performed on the edge of the recording medium, the amount of ink discharged from the first recording head 3 is set to be smaller than the amount of ink discharged from the second recording head 10. Is formed. Accordingly, when recording is performed by ejecting ink from the first recording head 3 prior to ejecting ink from the second recording head 10, the ink ejection amount can be suppressed to be relatively small. For this reason, when recording is performed by the first recording head 3 on the leading end portion of the recording medium that is easily deformed, it is possible to prevent the recording medium from being deformed by performing recording by ejecting an excessively large amount of ink. be able to. Accordingly, the recording medium is deformed when the second recording head 10 moves to the area where the recording has already been performed by the first recording head 3 after the ink is ejected by the first recording head 3. Thus, the contact between the recording medium and the second recording head 10 can be suppressed. As a result, the contact between the recording surface of the recording medium on which the image is recorded and the recording heads 3 and 10 can be suppressed, so that it is possible to suppress the quality of the recorded image from being deteriorated by the contact.

  Further, the recording medium is deformed by the recording performed by the preceding first recording head 3, so that the distance between the second recording head 10 and the recording medium is not constant. Recording can be suppressed. Accordingly, it is possible to suppress the occurrence of unevenness in the recorded image due to the non-uniform distance between the second recording head 10 and the recording medium, and the deterioration of the quality of the recorded image.

  In the present embodiment, as described above, the area where the recording rate is changed is limited to the front end and the rear end of the recording medium. For this reason, when recording is performed on an area other than the edge of the recording medium, a mask is used so that the recording rate is uniform between the respective scans. Accordingly, ink is ejected from the first recording head 3 and the second recording head 10 almost evenly according to the recording data, and recording is performed. Thus, when the entire recording process to the recording medium is taken into consideration, the difference in the frequency of ink ejection between the ink ejection from the first recording head 3 and the ink ejection from the second recording head 10 is considered. Can be kept small. Therefore, when the ink jet recording apparatus is used for a long period of time, the difference in the number of times the heating element is driven for ink ejection between the first recording head 3 and the second recording head 10 is small. Therefore, it is possible to suppress a difference in life between the first recording head 3 and the second recording head 10. Accordingly, the recording heads 3 and 10 can be used effectively over a longer period of time, and the service life of the ink jet recording apparatus can be extended.

  Furthermore, in the present embodiment, the recording rate at the time of recording in each pass changes from the first pass to the fourth pass. Thereby, it is possible to suppress the recording with a high recording rate in a specific pass, and the occurrence of image unevenness in the recorded image is reduced by increasing the density in the recording in the specific pass.

  In the present embodiment, the ink jet recording apparatus has two recording heads. However, the present invention is not limited to this, and the number of recording heads may be one or three or more. That is, when N-pass divided printing is used regardless of the number of heads used, the ink discharge amount consumed from the first pass to the N / 2 pass is consumed from the (N / 2 + 1) th pass to the Nth pass. Control may be performed so that the amount is less than the ink discharge amount.

  In the present embodiment, the present invention is applied when recording is performed on the end of the recording medium regardless of the format of the recorded image. However, the present invention is not limited to this, and the recording control of the present invention is applied when marginless recording is performed in which recording is performed without forming a margin at the end in the conveyance direction of the recording medium. May be. When a margin is formed at the end of the recording medium in the conveyance direction, the recording may not be performed in the conveyance direction of the recording medium depending on the size of the margin. In such a case, even if the recording control of the present invention is applied, the effect may not be obtained. Therefore, in such a case, the recording control of the present invention may not be performed.

(Second Embodiment)
Next, recording control in the ink jet recording apparatus according to the second embodiment will be described. In addition, about the part comprised similarly to said 1st embodiment, the same code | symbol is attached | subjected in a figure, description is abbreviate | omitted, and only a different part is demonstrated.

  The recording control of the second embodiment is different from the recording control of the first embodiment in that the control is executed by adding a determination based on the use environment condition (humidity). The ink jet recording apparatus according to the present embodiment includes a temperature / humidity sensor 107 (humidity detection means) that can detect the humidity in the periphery of the recording heads 3 and 10. FIG. 10 is a control flow of the ink jet recording apparatus according to the second embodiment. In the second embodiment, when it is determined in step 402 that the number of passes selected by the user is N = 4 or more, the flow proceeds to step 700, and it is determined whether the usage humidity is 30% or less. .

  When printing is started and it is determined in step 401 that the sheet is a target sheet, and in step 402 it is determined that the number of recording passes N = 4 or more, the process proceeds to step 700. In step 700, the humidity around the recording head is measured by the temperature / humidity sensor 107, and it is determined whether the usage environment humidity in which the inkjet recording apparatus is placed is 30% or less. If it is determined that the humidity is 30% or more, the flow proceeds to step 403 as out of the target of recording control according to the present invention. Accordingly, a mask in which the recording ratios of the first recording head 3 and the second recording head 10 are set uniformly is selected and recording is performed. If it is determined in step 700 that the humidity is 30% or less, the flow moves to step 404 and the recording control of the present invention is executed. Therefore, a non-uniform mask set so that the recording rates of the first recording head 3 and the second recording head 10 are different is selected and recording is performed. The subsequent control flow is the same as the control flow of the first embodiment.

  As described above, in the present embodiment, only when the humidity is lower than the predetermined humidity, the ink discharge amount from the first recording head 3 is made smaller than the ink discharge amount from the second recording head 10 to form an image. To do. That is, when the humidity in the peripheral portion of the recording heads 3 and 10 detected by the humidity sensor is equal to or lower than a predetermined threshold, the ink discharge amount from the first recording head 3 is the ink from the second recording head 10. Recording is controlled so as to be smaller than the discharge amount. As described above, in the second embodiment, the range to which the recording control according to the present invention is applied is limited to a low humidity environment (humidity of 30% or less). Thereby, under an environment where the humidity is higher than 30%, the recording control for providing a difference between the recording rate of ink ejection by the first recording head 3 and the recording rate of ink ejection by the second recording head 10 is performed. Not done. Originally, in a high humidity environment, even if recording is performed on the edge of the recording medium, the recording medium already contains moisture before recording, so that the recording medium is hardly deformed. Therefore, even if a difference is provided between the recording rate of ink ejection by the first recording head 3 and the recording rate of ink ejection by the second recording head 10, it is difficult to obtain the effect. Rather, by providing a difference between the recording rate of ink ejection by the first recording head 3 and the recording rate of ink ejection by the second recording head 10, the first recording head 3 and the second recording head 10. And the number of times of driving the heating element is different. As a result, when the ink jet recording apparatus is used for a long period of time, there is a difference in life between the first recording head 3 and the second recording head. Therefore, in the present embodiment, when the humidity around the recording heads 3 and 10 is high, a difference in recording rate between the first recording head 3 and the second recording head is prevented. Thereby, it is possible to suppress the occurrence of a difference in the lifetimes of the first recording head 3 and the second recording head 10. Accordingly, the respective recording heads 3 and 10 can be used effectively until the end of their lives, and the service life of the ink jet recording apparatus can be extended.

3 First recording head 10 Second recording head 100 Inkjet recording apparatus

Claims (5)

It has a recording head in which ejection openings for ejecting ink are arranged to form an ejection opening array, and the recording head scans in a main scanning direction that intersects the conveyance direction in which the recording medium is conveyed while conveying the recording medium. An inkjet recording apparatus that performs recording by ejecting ink onto a recording medium while performing recording, and the recording head scans a predetermined recording area a plurality of times.
A plurality of ejection ports forming ejection port arrays formed in the recording head are divided into two ejection port groups along the arrangement direction in which the ejection port arrays are arranged according to the positions where the ejection ports are formed, Of the two ejection port groups, when recording is performed on the end of the recording medium in the transport direction, ink per unit area of the recording medium is ejected from the first ejection port group that is used first. It has a first control means for controlling printing so that the discharge amount becomes smaller than the ink discharge amount per unit area of the recording medium by ink discharge from the second discharge port group used later. An inkjet recording apparatus. The discharge ports forming the discharge port array are divided into two equal parts so that the first discharge port group and the second discharge port group have the same number of discharge ports, respectively.
The first control unit is configured to perform ink ejection by the first ejection port group during the first to (N / 2) th scanning when printing is performed on the predetermined recording area by N scannings. In the second (N / 2 + 1) -th to N-th scans, ink is ejected from the second ejection port group, and the amount of ink ejected in the first to (N / 2) -th scans is 2. The ink jet recording apparatus according to claim 1, wherein the recording is controlled so as to be smaller than an amount of ink ejected in the (N / 2 + 1) th to N th scans.   When marginless recording is performed in which recording is performed without forming a margin at the end of the recording medium in the transport direction, the first control unit is configured to perform ink ejection from the first ejection port group. 2. The recording is controlled so that an ink discharge amount per unit area of the recording medium is smaller than an ink discharge amount per unit area due to ink discharge from the second discharge port group. Or the inkjet recording apparatus according to 2; Humidity detection means capable of detecting humidity at the periphery of the recording head,
When the humidity in the peripheral portion of the recording head detected by the humidity detecting unit is equal to or lower than a predetermined threshold, the first control unit is configured to print the recording medium by discharging the ink from the first discharge port group. 2. The recording is controlled so that an ink discharge amount per unit area is smaller than an ink discharge amount per unit area of the recording medium due to ink discharge from the second discharge port group. 4. The inkjet recording apparatus according to any one of items 1 to 3. The first recording head in which the ejection ports for ejecting ink are arranged to form the ejection port array, and the ejection ports in the same direction as the arrangement direction in which the ejection port array formed in the first recording head is arranged. And a second recording head in which the ejection port array is formed, and the first recording head and the second recording head are arranged in a transport direction in which the recording medium is transported while transporting the recording medium. While scanning in the intersecting main scanning direction, recording is performed by ejecting ink onto the recording medium, and the first recording head and the second recording head respectively scan a predetermined recording area. An ink jet recording apparatus for performing
Among the first recording head and the second recording head, when recording is performed on the end of the recording medium in the transport direction, ink is ejected from the first recording head first, and later When ink is ejected from the second recording head, the amount of ink ejected per unit area of the recording medium due to ink ejection from the first recording head is the recording due to ink ejection from the second recording head. An ink jet recording apparatus comprising: a second control unit that controls recording so as to be smaller than an ink discharge amount per unit area of a medium.

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