JP6149563B2 - Image forming apparatus, image forming control method, and image forming control program - Google Patents

Description

  The present invention relates to an image forming apparatus, an image formation control method, and an image formation control program. More specifically, the present invention prevents high-quality image formation by preventing image deterioration due to wrinkles and skew of a recording medium due to non-uniform moisture distribution. The present invention relates to an image forming apparatus, an image formation control method, and an image formation control program.

  An image forming apparatus, particularly an ink jet recording apparatus, forms an image by ejecting (discharging) ink droplets toward a recording medium such as paper. The ink jet recording apparatus can easily increase the speed, reduce noise, and color, and can perform printing (image formation) in a non-contact manner on a recording medium. Therefore, the ink jet recording apparatus has been conventionally used for various image forming applications, and has been widely used for public display applications such as photographs, posters, graphic prints, and trademark printing applications. . In addition, in the industrial field, the use of inkjet recording apparatuses is expanding because printing costs are lower than printing by plate making when printing various small numbers of copies.

  However, the ink jet recording apparatus performs printing by discharging ink as a liquid from a plurality of fine nozzles onto a recording medium such as paper.

  Since the ink is a material in which the coloring material is melted in a solvent (moisture), when ink is ejected onto the recording medium, the moisture contained in the ink soaks into the fibers constituting the recording medium. The recording medium expands.

  An ink jet recording apparatus does not form an image by uniformly ejecting ink onto a recording medium, but forms an image by ejecting ink only to a portion necessary for image formation based on image data. Therefore, variations occur in the ejection of ink on the recording medium. For example, if the amount of moisture (ink amount) varies in the area per unit area of the recording medium, the dimensional change varies, and the variation in the dimensional change causes the ink-attached portion to expand. A phenomenon called cockling (waving) occurs.

  For example, in a so-called continuous book machine that forms an image on a long sheet (recording medium), the sheet is pulled and conveyed in the conveying direction, so the sheet is pulled in the conveying direction over the entire width of the sheet, There is no local deformation of the paper in the transport direction. However, in the continuous book machine, the paper is free in the width direction (main scanning direction) perpendicular to the transport direction and is free of tensile force, and therefore is easily expanded and contracted in the width direction. Waves (cockling) may occur, which may reduce image quality.

  When cockling occurs in the recording medium, there is a problem that the transportability is deteriorated, the image quality is deteriorated, and the recording medium is clogged (jammed).

  Conventionally, a first nozzle that discharges a first liquid of a first liquid amount having a color material in a pixel according to image data of an image to be printed, and a total liquid amount discharged to the pixel are constant in a plurality of pixels. And a second nozzle that discharges a second liquid having a second liquid amount having transparency to the pixels, and the second liquid based on the difference between the total liquid amount and the first liquid amount based on the image data. There has been proposed a droplet discharge device having an arithmetic processing unit for obtaining an amount (see Patent Document 1).

  That is, in this prior art, in order to adjust the amount of water, the discharge amount of the transparent liquid discharged to the non-ink discharge portion is obtained for each pixel based on the image data.

  Further, conventionally, in an image recording apparatus for forming an image on a recording surface of a recording material by an ink or liquid visualization means, an image detection means for detecting an image density distribution or a print density distribution on the recording surface; Based on the image signal obtained from the image detection means, a print area calculation means for calculating the print distribution of the colorless transparent liquid, and a predetermined amount of the colorless transparent liquid based on the print area signal emitted from the print area calculation means An image recording apparatus provided with a print head for printing on a recording surface has been proposed (see Patent Document 2).

  That is, this prior art obtains a print distribution (non-ink ejection portion) for printing a colorless transparent liquid and its amount based on the image density distribution or print density distribution on the recording surface and the image signal.

  However, in the conventional techniques described in the above publications, since the discharge amount of the transparent liquid is determined based on the image density distribution, the print density distribution, or the image data, the elongation amount of the recording medium is set. There has been a need to improve the image quality and the recording medium transportability by appropriately equalizing.

  That is, the amount of ink used calculated from the image density and image data does not exactly match the actual amount of recording medium, and the type of recording medium and the printing environment (especially humidity) differ. And the amount of elongation of the recording medium is different. Therefore, it is not possible to accurately calculate the discharge amount of the transparent liquid for making the elongation of the recording medium uniform only from the ink density calculated from the image density and the image data, and improvement is necessary. there were. In recent years, the resolution of images has been increased, and in order to calculate the amount of ink used from image density and image data, the amount of calculation has become enormous, and the calculation for calculating the discharge amount of transparent liquid has There was a problem that it was not in time for the discharge timing of the transparent liquid.

  Accordingly, an object of the present invention is to quickly and accurately determine the amount of liquid ejected to a recording medium in order to adjust the elongation in the width direction of the recording medium.

  In order to achieve the above object, an image forming apparatus according to claim 1, wherein an image is formed by a recording head that forms an image by ejecting ink toward a recording medium in accordance with image data, and the recording head. Width detecting means for detecting a change in the width direction of the recording medium, a liquid discharge head for discharging a water replenishing liquid for replenishing the recording medium toward the recording medium, and orthogonal to the width direction For each predetermined adjustment area in the sub-scanning direction, based on the detection result of the width detection unit, the hydration liquid is discharged to a non-image forming area other than the image forming area by the recording head based on the image data in the width direction. A liquid discharge amount determining means for determining the amount; and for each adjustment region, causing the liquid discharge head to discharge the hydration liquid of the discharge amount determined by the liquid discharge amount determining means to the non-image forming region. It is characterized by comprising a liquid ejection head drive control means.

  According to the present invention, it is possible to quickly and accurately determine the amount of liquid ejected to a recording medium in order to adjust the elongation in the width direction of the recording medium.

1 is a schematic configuration diagram of an ink jet recording apparatus to which an embodiment of the present invention is applied. The figure which shows the relationship between the line head unit which specified the nozzle, and roll paper. FIG. 3 is a block diagram of a main part of the ink jet recording apparatus. The figure which shows an example of a discharge amount table. The figure which shows the other example of a discharge amount table. The figure which shows an example of the dot pattern of 20% of printing rates. The figure which shows an example of the dot pattern of 40% of printing rates. The figure which shows an example of the dot pattern of 60% of printing rates. The figure which shows an example of the dot pattern of 80% of printing rates. The figure which shows an example of the dot pattern produced | generated at random with the printing rate of 60%. The figure which shows an example of the dot pattern of 20% to 100% of the printing rate by a dot diameter system. 5 is a flowchart showing image formation control processing. FIG. 6 is a diagram illustrating an example of an image formed on roll paper. The figure which shows an example of the prescription | regulation dot pattern of the transparent ink with respect to a non-image formation area. The figure which shows an example of the random dot pattern of the transparent ink with respect to a non-image formation area. The figure which shows an example of the dot pattern by the dot diameter system of the transparent ink with respect to a non-image formation area.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, since the Example described below is a suitable Example of this invention, various technically preferable restrictions are attached | subjected, However, The range of this invention is unduly limited by the following description. However, not all the configurations described in the present embodiment are essential constituent elements of the present invention.

  1 to 16 are diagrams showing an embodiment of an image forming apparatus, an image forming control method, and an image forming control program according to the present invention. FIG. 1 is an image forming apparatus, an image forming control method, and an image according to the present invention. It is a principal part schematic block diagram of the inkjet recording device 1 to which one Example of the formation control program was applied.

  In FIG. 1, an ink jet recording apparatus (image forming apparatus) 1 includes a paper transport unit 2, an image forming unit 3, a paper width detection sensor 4, and the like, and forms an image on a long roll paper (recording medium) P. (Print).

  The paper transport unit 2 includes a paper feed roller 21, a paper feed side transport roller pair 22, a plurality of transport rollers 23, a paper discharge side transport roller 24, a take-up roller 25, and the like.

  The paper feed roller 21 rotatably supports a roll paper bundle around which a roll paper P having a predetermined length is wound, and the leading end of the roll paper P is transported on the paper feed side disposed in the vicinity of the paper feed roller 21. The roller pair 22 is inserted between the rollers.

  The pair of paper feed-side transport rollers 22 is driven to rotate by a drive motor (not shown), thereby feeding the roll paper P in the transport direction indicated by the arrow in FIG. 1 (from right to left in FIG. 1).

  In the transport roller 23, a plurality of rollers are horizontally arranged in the transport direction of the roll paper P, and the roll paper P sent out from the paper-feed-side transport roller pair 22 is maintained in the horizontal state in the transport direction. Transport to.

  The paper discharge-side transport roller 24 guides the roll paper P transported by the transport roller 23 to the take-up roller 25.

  The take-up roller 25 is driven to rotate by a drive motor (not shown) and takes up the roll paper P sent out from the paper feed roller 21.

  The image forming unit 3 includes a colored line head unit 31, a transparent line head unit 32, and the like.

  The colored line head unit (recording head) 31 is provided with line head units 31Bk, 31C, 31M, and 31Y for black Bk, cyan C, magenta M, and yellow Y that are sequentially arranged in the transport direction. As shown in FIG. 2, the line head units 31Bk, 31C, 31M, and 31Y for each color are arranged in a state that extends in the main scanning direction (width direction of the roll paper P) longer than the width of the roll paper P. Yes. The line head units 31Bk, 31C, 31M, and 31Y for each color have a large number of ink ejection nozzles 31Bkn, 31Cn, 31Mn, and 31Yn arranged on the surface of the roll paper P in the main scanning direction. Each of the ink discharge nozzles 31Bkn, 31Cn, 31Mn, and 31Yn discharges the corresponding color ink toward the roll paper P that is being transported by the transport roller 23.

  The line head units 31Bk, 31C, 31M, and 31Y for each color are arranged in the order of the line head unit 31Bk → the line head unit 31C → the line head unit 31M → the line head unit 31Y in the transport direction indicated by the arrow in FIG. ing. The line head units 31Bk, 31C, 31M, and 31Y for the respective colors discharge the corresponding inks so as to overlap each other in a state where colors are formed on the same dots in synchronization with the transport of the roll paper P by the paper transport unit 2. Thus, a dot image having a color corresponding to the image data is formed. The ink of each color ejected from the line head units 31Bk, 31C, 31M, and 31Y of each color is mainly used in which a colorant such as a pigment is dissolved in a solvent, but the ink configuration is limited to such a configuration. For example, a dye may be used as a colorant.

  In the ink jet recording apparatus 1, a transparent line head unit 32 is disposed on the downstream side in the transport direction at a predetermined interval from the line head unit 31 </ b> Y of the colored line head unit 31.

  The colored line head unit 31 is not limited to the black Bk, cyan C, magenta M, and yellow Y line head units 31Bk, 31C, 31M, and 31Y. For example, the colored line head unit 31 may include a line head unit that discharges light colors such as light gray, light cyan, and light magenta, and other special colors. Further, the arrangement order of the line head units 31Bk, 31C, 31M, and 31Y is not limited to the above arrangement order.

  As shown in FIG. 2, the transparent line head unit (liquid discharge head) 32 is disposed in a state extending longer than the width of the roll paper P in the main scanning direction. A large number of ink discharge nozzles 32n are arranged in the main scanning direction. The ink discharge nozzle 32n discharges transparent ink (hereinafter, referred to as “transparent ink” as appropriate) toward the roll paper P being conveyed by the conveyance roller 23 and the discharge-side conveyance roller 24.

  The transparent ink (moisture replenishing liquid) is a transparent liquid having a viscosity and a surface tension suitable for discharging from the ink discharge nozzles 32n of the transparent line head unit 32. As the transparent ink, an appropriate liquid can be used as long as it is a liquid that replenishes the roll paper P without impairing the storage stability and safety as a printed matter. The transparent ink is preferably an ink (solvent) that does not contain a color material. In other words, ink that does not include a color material can match the ink permeability and wetness without greatly changing the composition of the colored ink ejected from the line head units 31Bk, 31C, 31M, and 31Y of the respective colors. . The transparent ink is not limited to the above, and may be water, for example.

  The line head units 31Bk, 31C, 31M, and 31Y for each color and the transparent line head unit 32 can use appropriate driving methods as their driving methods. For example, an on-demand type head that uses an actuator such as a piezoelectric method using a piezoelectric element such as PZT (lead zirconate titanate), a thermal energy method that applies thermal energy, an electrostatic method that uses electrostatic force, or a continuous jet type A charge control head or the like can be used.

  The paper width detection sensor (width detection means) 4 is disposed between the colored line head unit 31 and the transparent line head unit 32, and detects the width length (length in the width direction) of the roll paper P. . For example, as shown in FIG. 2, the paper width detection sensor 4 uses a laser displacement meter, and detects the width length of the roll paper P by measuring the distance between both end positions in the width direction of the roll paper P. . In this case, the paper width detection sensor 4 is disposed directly above the conveyance roller 23, and the roll paper P is determined based on the distance difference between the end of the roll paper P and the conveyance roller 23 positioned below the roll paper P. , And the width and length of the roll paper P are detected in a non-contact manner from the both end position data. The paper width detection sensor 4 is not limited to the one using the above laser displacement meter. For example, the camera is used to photograph both ends of the roll paper P with high accuracy, and the end of the roll paper P is captured. The width and length of the roll paper P may be detected in a non-contact manner by detecting the portion.

  The inkjet recording apparatus 1 has a block configuration as shown in FIG. The ink jet recording apparatus 1 includes a main control unit 101, a colored ink head control unit 102, a transparent ink head control unit 103, the colored line head unit 31, the transparent line head unit 32, a paper width detection sensor 4, and the like. In addition to the above-described units, the inkjet recording apparatus 1 includes each unit necessary for the inkjet recording device 1, for example, a conveyance drive unit and a communication unit (not shown). In particular, the inkjet recording apparatus 1 includes an environmental detection sensor (environment detection unit) that detects at least one of environmental conditions around the inkjet recording apparatus 1, particularly temperature and humidity, for example, a temperature sensor, a humidity sensor, and the like. I have.

  The main control unit 101 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an ASIC (Application Specific Integrated Circuit), a communication IF (interface), and the like.

  The inkjet recording apparatus 1 includes a ROM, an EEPROM (Electrically Erasable and Programmable Read Only Memory), an EPROM, a flash memory, a flexible disk, a CD-ROM (Compact Disc Read Only Memory), a CD-RW (Compact Disc Rewritable), and a DVD. An image formation control program for executing the image formation control method of the present invention recorded on a computer-readable recording medium such as a (Digital Versatile Disk), an SD (Secure Digital) card, or an MO (Magneto-Optical Disc) is read. Thus, the amount of the transparent ink discharged onto the roll paper P can be quickly and accurately adjusted in order to adjust the elongation in the width direction of the roll paper P that is a recording medium to be described later. It is constructed as an image forming apparatus that executes a desired image formation control method. This image formation control program is a computer-executable program written in a legacy programming language such as assembler, C, C ++, C #, Java (registered trademark), an object-oriented programming language, or the like, and is stored in the recording medium. And can be distributed.

  The main control unit (liquid discharge amount determining means) 101 stores a basic program as the ink jet recording apparatus 1 and an image formation control program for executing the image formation control method of the present invention in the ROM. The main control unit 101 performs basic processing as the ink jet recording apparatus 1 by controlling each part of the ink jet recording apparatus 1 while the CPU uses the RAM as a work memory based on a program in the ROM, The image formation control process of the present invention is executed. The main control unit 101 communicates with a host device such as an external computer via the communication IF under the control of the CPU, and receives image formation information (print job or the like) such as image data. Further, the main control unit 101 performs image processing necessary for image formation on the image data received by the ASIC from the host device under the control of the CPU.

  The main control unit 101 performs image processing on the received image data, determines the ink discharge amount and discharge timing of each color, and outputs the determined color head drive data to the color ink head control unit 102.

  The main control unit 101 sets one line or a predetermined number of lines as the adjustment length (adjustment area) from the image data and the paper width detection result detected by the paper width detection sensor 4, and discharges the transparent ink at the adjustment length. Determination of an image forming area and a discharge amount of transparent ink to the non-image forming area are determined. That is, the main control unit 101 determines a non-image forming area in the main scanning direction with the adjustment length, and sets the printing rate (discharge amount) of the transparent ink to the non-image forming area in the width direction of the roll paper P. The amount of change is determined as the amount to be uniformized. When the printing rate is determined, the main control unit 101 generates transparent head drive data for discharging transparent ink at the printing rate, and outputs it to the transparent ink head control unit 103.

  The main control unit 101 stores, for example, a discharge amount table in which the sheet width elongation rate and the transparent ink printing rate correspond to each other in the ROM or the like, as shown in FIG. The printing rate is determined by calculating and referring to the ejection amount table based on the calculated elongation rate. The printing rate (discharge amount) of the transparent ink with respect to the elongation rate of the paper width is such that the elongation rate in the width direction of the roll paper P is uniform in the necessary sub-scanning range by discharging the transparent ink to the non-image forming area. This is the printing rate necessary for the conversion, and is determined by experiments or the like. The printing rate is not a fixed value, and is appropriately changed as shown in FIG. 5, for example, depending on the type of roll paper P, environmental conditions, and the like. The numerical values shown in FIG. 4 and FIG. 5 are examples, and before changing the print rate of the transparent ink in several stages, the elongation rate of the paper width at that time is obtained and the value is obtained from the value. The relationship between the expansion rate of the paper width and the discharge amount (printing rate) of the transparent ink discharged to the non-image forming area may be determined.

  The main control unit 101 first calculates the paper width from the both end positions of the roll paper P detected by the paper width detection sensor 4 for the elongation rate of the paper width, and based on this paper width, the following is performed. ,calculate. That is, the main control unit 101 calculates the paper width of the roll paper P before image formation based on the detection result of the paper width detection sensor 4, and sets it as “paper width in a blank sheet state”. Next, the main control unit 101 performs image formation on the roll paper P in the sub-scanning direction (one page area, hereinafter referred to as a printing area as appropriate) after the colored line head unit 31 forms an image. The paper width of the roll paper P is calculated based on the detection result of the paper width detection sensor 4 for each of the adjustment lengths, and is defined as “paper width of the printing area”. When the main control unit 101 obtains “paper width in blank state” and “paper width in the print area” for each adjustment length, the main control unit 101 next determines the elongation in the width direction of the roll paper P by the following equation (1). Thus, it is calculated as “paper width growth rate”.

Elongation rate of paper width = (paper width of printing area−paper width of blank sheet) / paper width of blank sheet (1)
When the main control unit 101 calculates the expansion rate of the paper width, the discharge amount of the transparent ink is calculated with respect to the non-image forming area in the main scanning direction at a predetermined sub-scanning length such as for each line using the discharge amount table. Obtain the printing rate.

  When the main control unit 101 obtains the printing rate, it generates transparent head drive data corresponding to the printing rate. The main control unit 101 determines a dot formation pattern corresponding to the printing rate using a mask method, a dot diameter method, and the like, and generates transparent head drive data for driving the ink discharge nozzles 32n with the dot formation pattern.

  That is, for example, in the case of the mask method, the main control unit 101, as shown in FIGS. 6 to 9, has a mask pattern of 1 × 10 dots and a non-image forming area image data (white Transparent head drive data is generated by calculating a logical sum with the dot. For example, the printing rate of the transparent ink with respect to the non-image forming area is 20% in FIG. 6, 40% in FIG. 7, 60% in FIG. 8, and 80% in FIG. A pattern is assigned. Further, when the same printing rate continues, the main control unit 101 appropriately sets the same printing rate for each line or for each adjustment length, as shown in FIGS. 6 to 9 (a) to (e). By changing the specified dot pattern, it is possible to prevent the dots of transparent ink from continuing. That is, in FIGS. 6 to 9, prescribed dot patterns having the same printing rate but different dot positions are described in (a) to (e) of each drawing. The main control unit 101 uses these dot patterns as mask patterns to perform a logical sum with the image data in the non-image forming area, but stores the prescribed dot pattern in a memory such as an internal ROM. ing.

  In addition, the dot pattern is not limited to a preset prescribed dot pattern. For example, as shown in FIG. 10, a dot pattern corresponding to the printing rate may be appropriately generated using a random number.

  The main control unit 101 may generate dots by a dot diameter method, for example, as shown in FIG. 11, in addition to a method of selecting a prescribed dot pattern or random generation. In this case, for example, when the printing rate is 100%, the main control unit 101 has a droplet amount of 20 pl as shown in FIG. 11A, and when the printing rate is 80%, as shown in FIG. When the droplet amount is 16 pl and the printing rate is 60%, the droplet amount is 12 pl as shown in FIG. 11C, and when the printing rate is 40%, the droplet amount is 8 pl as shown in FIG. When the rate is 20%, the drop amount is 4 pl as shown in FIG. In the case of the dot diameter method, the main control unit 101 generates transparent head drive data that applies a dot pattern having a droplet amount corresponding to the printing rate to all the dots in the non-image forming area, and generates a transparent ink head control unit. To 103.

  The colored ink head control unit 102 controls the driving of the line head units 31Bk, 31C, 31M, and 31Y of each color in the colored line head unit 31 based on the colored head drive data received from the main control unit 101. Specifically, the colored ink head control unit 102 controls the drive timing and drive amount of each of the ink discharge nozzles 31Bkn, 31Cn, 31Mn, and 31Yn of the line head units 31Bk, 31C, 31M, and 31Y, and controls the roll paper P. The ink ejection amount for each dot arranged in the main scanning direction is controlled.

  The transparent ink head control unit (liquid ejection head drive control means) 103 controls the drive of the transparent line head unit 32 based on the transparent head drive data received from the main control unit 101. Specifically, the transparent ink head control unit 103 controls the drive timing and the drive amount of each ink discharge nozzle 32n of the transparent line head unit 32 to discharge the transparent ink to the non-image forming area.

  Next, the operation of this embodiment will be described. The ink jet recording apparatus 1 of the present embodiment uses the amount of liquid ejected to the roll paper P in order to adjust the elongation in the width direction of the roll paper P, that is, the amount of transparent ink ejected to the non-image forming area of the roll paper. Seek promptly and accurately.

  The inkjet recording apparatus 1 uses the paper transport unit 2 to feed the roll paper P supported by the paper feed roller 21 to the image forming unit 3 and the paper width by the paper feed side transport roller pair 22, the transport roller 23, and the paper discharge side transport roller 24. The lower part of the detection sensor 4 is conveyed in the horizontal direction. The ink jet recording apparatus 1 winds the roll paper P transported by the paper transport unit 2 around the take-up roller 25.

  The inkjet recording apparatus 1 forms an image by ejecting ink droplets of each color from the line head units 31Bk, 31C, 31M, and 31Y of each color of the colored line head unit 31 onto the roll paper P conveyed by the paper conveyance unit 2. To do. In this case, in the inkjet recording apparatus 1, the colored ink head control unit 102 controls the driving of the ink discharge nozzles 31Bkn, 31Cn, 31Mn, and 31Yn included in the line head units 31Bk, 31C, 31M, and 31Y of the respective colors, Controls ink ejection. In the ink jet recording apparatus 1, the main control unit 101 determines the ink discharge amount and discharge timing of each color based on the image data, and outputs the determined color head drive data to the color ink head control unit 102.

  However, the roll paper P expands due to the moisture of the ink when the ink is ejected and attached. The expansion of the roll paper P occurs in the main scanning direction and the sub-scanning direction. However, since the sub-scanning direction is pulled by the paper transport unit 2, the expansion affects the image quality and the paper transport performance. There is almost no effect.

  However, the expansion of the roll paper P in the sub-scanning direction (width direction) is free because the roll paper P is not subjected to a tensile force in the width direction. Therefore, the roll paper P is easily expanded and contracted in the width direction when the ink of each color is sprayed, and the paper wavy (cockling) is generated, which may deteriorate the image quality.

  Therefore, the ink jet recording apparatus 1 according to the present embodiment adjusts the discharge amount of the transparent ink discharged to the non-image forming area based on the image data and the change amount in the width direction of the roll paper P, so that the roll paper P The horizontal expansion and contraction in the width direction is made uniform to improve the image quality and the paper conveyance performance.

  That is, when the main control unit 101 receives image data from the host device and is instructed to start the printing process, as shown in FIG. 12, the sheet width detection sensor 4 determines the sheet width in a blank state before image formation. Are detected and stored in the memory (step S101).

  When the main control unit 101 detects the width of the roll paper P, the main control unit 101 performs necessary image processing on the image data, generates the colored head drive data, and outputs the generated color head drive data to the colored ink head control unit 102. The colored ink head control unit 102 controls the driving of the color line head units 31Bk, 31C, 31M, and 31Y of the colored line head unit 31 based on the colored head driving data, and discharges the ink of each color onto the roll paper P to generate an image. Printing to be formed is started (step S102).

  When the printing is started, the main control unit 101 detects the paper width based on the detection result of the paper width detection sensor 4 in the entire sub-scanning direction of the print area, and the elongation ratio of the paper width is calculated by Expression (1). Is calculated (step S103).

  When the main control unit 101 calculates the expansion rate of the paper width, as described above, the main control unit 101 obtains the printing rate of the transparent ink, generates the transparent head drive data of the dot pattern that becomes the printing rate, and generates the transparent ink head control unit. It outputs to 103 (step S104).

  In this case, as described above, the main control unit 101 obtains the printing rate for each predetermined adjustment length in the printing area, and generates transparent head drive data of a dot pattern corresponding to the printing rate. .

  When the main control unit 101 generates the transparent head drive data, the main control unit 101 outputs the transparent head drive data to the transparent ink head control unit 103 to drive and control each ink discharge nozzle 32n of the transparent line head unit 32 to roll the transparent ink. The ink is discharged onto the paper P (step S105).

  When the main control unit 101 causes the transparent ink to be ejected, the main control unit 101 checks whether the printing has been completed, that is, whether the printing process and the ejection of the transparent ink have been completed up to the end of the printing area (step S106).

  If printing is not completed in step S106 (NO in step S106), the main control unit 101 returns to step S103 and performs the same processing as described above from detection of the paper width (steps S103 to S106). ).

  When printing is finished in step S106, the image forming process with paper width adjustment is finished.

  In the image formation, for example, an image as shown in FIG. 13 is formed on the print area Pa. In the sub-scanning direction, the sheet width elongation rate is 0.4%, 0.2%, and Assume that there was a 0% area. Based on the sheet width elongation rate, the main control unit 101 refers to, for example, the discharge amount table in FIG. 20% is set for the region having an elongation rate of 0.2%, and 0% is set for the region having an elongation rate of 0%.

  The main control unit 101 generates transparent head drive data having a dot pattern as shown in FIGS. 6 to 9 when the transparent ink dot pattern is generated using the above-described mask method and the prescribed dot pattern. To do. In this case, as shown in FIG. 14, the main control unit 101 arranges dot patterns having the same printing rate in a region where the same printing rate is continuous for a plurality of lines but having different dot arrangements for each line. Therefore, the same dot pattern should not be continuous. In FIG. 14, the main control unit 101 includes a region with a printing rate of 60%, a region with a printing rate of 20%, and a region with a printing rate of 0%, but the transparent ink is discharged at 60% and 20%. Transparent ink is not ejected only in the area, and in the 0% area. In the 60% and 20% areas, the main control unit 101 uses the dot patterns that have the respective printing ratios and the dot patterns in which the same dot pattern is not continuous as a mask pattern to perform logic with the image data in the non-image forming area. The transparent head drive data is generated by taking the sum.

  In addition, when the main control unit 101 forms an image with an expansion rate of the paper width as shown in FIG. 13 in the image forming area, the main control unit 101 does not generate the transparent ink dot pattern using the mask method. As shown in FIG. 6, a randomly generated dot pattern may be used instead of the prescribed dot pattern.

  That is, the main control unit 101 randomly generates a dot pattern corresponding to each printing rate using a random number for a region where the printing rate of the transparent ink for the non-image forming region is 60% and 20%. . Then, the main control unit 101 uses the generated dot pattern as a mask pattern to perform a logical sum with the image data in the non-image forming area to generate transparent head drive data.

  Further, when an image having a paper width elongation rate as shown in FIG. 13 is formed in the image forming area, the main control unit 101 responds to the printing rate of the transparent ink in the non-image forming area as shown in FIG. Thus, a dot pattern with the dot diameter adjusted may be generated. That is, in FIG. 16, the main control unit 101 has a dot amount of 12 pl (corresponding to a printing rate of 60%) in all dots in a non-image forming region corresponding to a paper width elongation rate of 0.4%. Generate a pattern. Further, the main control unit 101 generates a dot pattern having a droplet amount of 4 pl (corresponding to a printing rate of 20%) for all dots in a non-image forming region corresponding to a sheet width elongation rate of 0.2%. .

  The main control unit 101 generates a dot pattern by any of the above methods, with respect to a non-image forming region corresponding to a region where the printing rate is 0%, that is, the paper width elongation rate is 0%. Is a dot pattern that does not eject transparent ink.

  The main control unit 101 adjusts the printing rate based on at least one of the temperature and humidity detected by the environmental sensor in setting the printing rate. That is, in the inkjet recording apparatus 1, the degree of elongation of the roll paper P by the transparent ink varies depending on the temperature and humidity during image formation (printing). Accordingly, the main control unit 101 refers to the ejection amount table shown in FIG. 4 based on the elongation rate of the paper width when either or both of temperature and humidity are less than 25 ° C. and less than 50%, for example. To determine the printing rate of the transparent ink. For example, when the temperature is 25 ° C. or higher and the humidity is 50% or higher, the main control unit 101 determines the printing rate of the transparent ink based on the ejection amount table shown in FIG.

  In this way, the change in the degree of elongation of the roll paper P due to the temperature and humidity when the transparent ink is discharged onto the roll paper P is offset, and the rippling (cockling) of the roll paper P is more appropriately suppressed. Can do.

  As described above, the ink jet recording apparatus 1 according to the present exemplary embodiment ejects ink of each color of black Bk, cyan C, magenta M, and yellow Y toward the roll paper (recording medium) P according to the image data. A color line head unit (recording head) 31 that forms the image, a paper width detection sensor (width detection means) 4 that detects a change in the width direction of the roll paper P formed by the color line head unit 31, and the roll paper P A transparent line head unit (liquid discharge head) 32 that discharges transparent ink (hydration replenisher) for replenishing water to the roll paper P, and a predetermined adjustment region in the sub-scanning direction orthogonal to the width direction. Based on the detection result of the paper width detection sensor 4, non-image formation other than the image formation region by the colored line head unit 31 based on the image data in the width direction A main control unit (liquid discharge amount determining means) 101 that determines the discharge amount of the transparent ink with respect to the area, and the transparent ink of the discharge amount determined by the main control unit 101 is transparent to the non-image forming region for each of the adjustment regions. And a transparent ink head control unit (liquid discharge head drive control means) 103 for causing the line head unit 32 to discharge.

  Therefore, in order to adjust the non-uniform elongation in the width direction of the roll paper (recording medium) P due to the water of each color ink of black Bk, cyan C, magenta M, and yellow Y discharged for image formation. In addition, the discharge amount (liquid amount) of the transparent ink discharged to the non-image forming area of the roll paper P can be quickly and accurately obtained. As a result, the non-uniformity in the width direction of the roll paper P can be adjusted quickly and accurately, and the image quality and the conveyance performance of the roll paper P can be improved.

  Further, the ink jet recording apparatus 1 of the present embodiment ejects black Bk, cyan C, magenta M, and yellow Y inks from the colored line head unit 31 toward the roll paper P in accordance with the image data. An image recording processing step to be formed, a width detection processing step for detecting a change in the width direction of the roll paper P on which an image is formed in the image recording processing step, and transparent ink from the transparent line head unit 32 toward the roll paper P. Based on the detection result in the width detection processing step for each of the predetermined adjustment areas in the sub-scanning direction orthogonal to the width direction by discharging and replenishing the roll paper P with water. Transparent ink ejection to non-image forming areas other than the image forming area in the image recording processing step based on the image data in the width direction A liquid discharge amount determination processing step for determining the liquid discharge amount, and for each adjustment region, the transparent line head unit 32 discharges the transparent ink of the discharge amount determined in the liquid discharge amount determination processing step to the non-image forming region. An image forming control method including an ejection head drive control processing step is executed.

  Therefore, in order to adjust the non-uniform elongation in the width direction of the roll paper (recording medium) P due to the water of each color ink of black Bk, cyan C, magenta M, and yellow Y discharged for image formation. In addition, the discharge amount (liquid amount) of the transparent ink discharged to the non-image forming area of the roll paper P can be quickly and accurately obtained. As a result, the non-uniformity in the width direction of the roll paper P can be adjusted quickly and accurately, and the image quality and the conveyance performance of the roll paper P can be improved.

  Further, the ink jet recording apparatus 1 according to the present exemplary embodiment applies a black Bk, cyan C, magenta M, and yellow Y ink to the roll paper P according to the image data from the colored line head unit 31 to a control processor such as a CPU. An image recording process for forming an image by discharging toward the roll, a width detection process for detecting a change in the width direction of the roll paper P formed by the image recording process, and a direction from the transparent line head unit 32 toward the roll paper P. Based on the detection result in the width detection process for each of the predetermined adjustment areas in the sub-scanning direction orthogonal to the width direction and the hydration liquid discharge process for discharging the transparent ink to replenish the roll paper P with water. Liquid discharge for determining the amount of transparent ink discharged to a non-image forming area other than the image forming area in the image recording process based on the image data in the width direction A determination process, and a liquid discharge head drive control process for causing the transparent line head unit 32 to discharge the transparent ink of the discharge amount determined in the liquid discharge amount determination process to the non-image forming area for each adjustment region. An image formation control program to be executed is installed.

  Therefore, in order to adjust the non-uniform elongation in the width direction of the roll paper (recording medium) P due to the water of each color ink of black Bk, cyan C, magenta M, and yellow Y discharged for image formation. In addition, the discharge amount (liquid amount) of the transparent ink discharged to the non-image forming area of the roll paper P can be quickly and accurately obtained. As a result, the non-uniformity in the width direction of the roll paper P can be adjusted quickly and accurately, and the image quality and the conveyance performance of the roll paper P can be improved.

  Further, in the ink jet recording apparatus 1 of this embodiment, as the width of the roll paper P detected by the paper width detection sensor (width detection means) 4 by the main control unit 101 as the liquid discharge amount determination means increases, the transparent ink The discharge amount is increased.

  Accordingly, it is possible to adjust the amount of the transparent ink in accordance with the amount of change in the width of the roll paper P due to moisture during image formation. As a result, the non-uniformity in the width direction of the roll paper P can be adjusted quickly and more accurately, and the image quality and the transport performance of the roll paper P can be further improved.

  Further, the ink jet recording apparatus 1 of the present embodiment further includes an environment detection sensor (environment detection means) that detects at least one of the temperature and humidity of the surrounding environment as an environmental condition, and the main control unit 101 has a sheet width. Based on the detection result of the detection sensor 4 and the environmental condition detected by the environment detection sensor, the discharge amount of the transparent ink is determined.

  Therefore, it is possible to adjust the amount of the transparent ink in accordance with the environmental conditions. As a result, the non-uniformity in the width direction of the roll paper P can be adjusted quickly and more accurately, and the image quality and the transport performance of the roll paper P can be further improved.

  Further, in the ink jet recording apparatus 1 of the present embodiment, the main control unit 101 as the liquid discharge amount determining unit is configured to cause the transparent ink discharge amount to be discharged from the transparent line head unit 32 in the adjustment region. And the position of the dot.

  Therefore, it is possible to discharge transparent ink efficiently and without bias. As a result, the non-uniformity in the width direction of the roll paper P can be adjusted quickly and more accurately, and the image quality and the transport performance of the roll paper P can be further improved.

  Further, in the ink jet recording apparatus 1 of the present embodiment, the main control unit 101 as the liquid discharge amount determining unit is configured to cause the transparent ink discharge amount to be discharged from the transparent line head unit 32 in the adjustment region. The discharge amount of the transparent ink is determined for each.

  Therefore, the transparent ink can be uniformly ejected to the non-image forming area of the roll paper P. As a result, the non-uniformity in the width direction of the roll paper P can be adjusted quickly and more accurately, and the image quality and the transport performance of the roll paper P can be further improved.

  In the above description, the inkjet recording apparatus 1 has been described. However, an inkjet image forming mechanism is also used for a single apparatus such as a copying apparatus, a facsimile apparatus, and a composite apparatus provided with the inkjet image forming unit. The same can be applied to an image forming system used as a part of the system.

  The invention made by the present inventor has been specifically described based on the preferred embodiments. However, the present invention is not limited to that described in the above embodiments, and various modifications can be made without departing from the scope of the invention. It goes without saying that it is possible.

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 2 Paper conveyance part 3 Image formation part 4 Paper width detection sensor 21 Paper feed roller 22 Paper feed side conveyance roller pair 23 Conveyance roller 24 Paper discharge side conveyance roller 25 Winding roller 31 Colored line head units 31Bk, 31C, 31M, 31Y Line head unit 31Bkn, 31Cn, 31Mn, 31Yn Ink discharge nozzle 32 Transparent line head unit 32n Ink discharge nozzle 101 Main control unit 102 Colored ink head control unit 103 Transparent ink head control unit P Roll paper

JP 2008-290286 A Japanese Patent Laid-Open No. 04-358836

Claims (7)

A recording head that forms an image by ejecting ink toward a recording medium according to image data;
Width detection means for detecting a change in the width direction of the recording medium on which an image is formed by the recording head;
A liquid ejection head for ejecting a hydration liquid for replenishing the recording medium toward the recording medium;
For each predetermined adjustment region in the sub-scanning direction orthogonal to the width direction, based on the detection result of the width detection unit, a non-image formation region other than the image formation region by the recording head based on the image data in the width direction. A liquid discharge amount determining means for determining a discharge amount of the hydration liquid;
Liquid discharge head drive control means for causing the liquid discharge head to discharge the water replenishment liquid of the discharge amount determined by the liquid discharge amount determination means to the non-image forming area for each adjustment region;
An image forming apparatus comprising: The liquid discharge amount determining means includes
The image forming apparatus according to claim 1, wherein the discharge amount of the hydration liquid is increased as the width of the recording medium detected by the width detection unit is increased. The image forming apparatus includes:
An environmental detection means for detecting at least one of temperature and humidity of the surrounding environment as an environmental condition;
The liquid discharge amount determining means includes
3. The image forming apparatus according to claim 1, wherein the discharge amount of the hydration liquid is determined based on a detection result of the width detection unit and an environmental condition detected by the environment detection unit. The liquid discharge amount determining means includes
4. The discharge amount of the hydration liquid is determined as the number of dots and the positions of the dots for discharging the hydration liquid from the liquid discharge head in the adjustment area. An image forming apparatus according to claim 1. The liquid discharge amount determining means includes
The discharge amount of the hydration liquid is determined as the discharge amount of the hydration liquid for each dot for discharging the hydration liquid from the liquid discharge head in the adjustment region. The image forming apparatus according to any one of the above. An image recording processing step of forming an image by ejecting ink toward a recording medium in accordance with image data from the recording head;
A width detection processing step for detecting a change in the width direction of the recording medium on which an image is formed in the image recording processing step;
A water replenishment liquid discharge processing step for replenishing the recording medium with water by discharging a water replenishment liquid from the liquid discharge head toward the recording medium;
For each predetermined adjustment area in the sub-scanning direction orthogonal to the width direction, based on the detection result in the width detection processing step, other than the image forming area in the image recording processing step based on the image data in the width direction A liquid discharge amount determination processing step for determining a discharge amount of the hydration liquid to the non-image forming region;
A liquid discharge head drive control processing step for causing the liquid discharge head to discharge the water replenishment liquid of the discharge amount determined in the liquid discharge amount determination processing step to the non-image forming region for each adjustment region;
An image formation control method comprising: To the control processor,
Image recording processing for forming an image by ejecting ink toward a recording medium in accordance with image data from the recording head; and
A width detection process for detecting a change in the width direction of the recording medium on which an image is formed by the image recording process;
A water replenishment liquid ejection process for replenishing the recording medium with water by ejecting a water replenishment liquid from the liquid ejection head toward the recording medium;
For each predetermined adjustment area in the sub-scanning direction orthogonal to the width direction, a non-image other than the image forming area in the image recording process based on the image data in the width direction based on the detection result in the width detection process A liquid discharge amount determination process for determining a discharge amount of the hydration liquid to the formation region;
A liquid discharge head drive control process for causing the liquid discharge head to discharge the water replenishment liquid of the discharge amount determined in the liquid discharge amount determination process for each adjustment region;
An image formation control program for executing

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