JP2013173313A - Inkjet recording apparatus and method, and method for manufacturing sanitary product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of troubles of a plurality of head units upon printing of images for a long period of time, reduce the load of the head units, and prevent reduction in image quality.SOLUTION: In a first operation mode, two head units A and B are retained at printing positions and subjected to printing operation. In a second operation mode, one head unit of the head units A and B escapes to a maintenance position, and the other head unit is retained at the printing position to carry out printing operation. The first operation mode and the second operation mode are alternately repeated, and the head units sequentially escape to the maintenance position and subjected to maintenance each time the mode is switched to the second operation mode. When an image is to be printed on an unwoven cloth 102 by the two head units A and B in the first operation mode, one of the head units A and B is alternately allocated to each of printing regions corresponding to one product to print the image, thereby enabling good printing of the image.

Description

  The present invention relates to an inkjet recording apparatus and method, and a method for manufacturing a sanitary article, and more particularly to a technique for printing an image continuously for a long time on a long recording medium.

  PP (polypropylene) nonwoven fabric, which is a raw material for sanitary goods, is as long as several kilometers, and when printing on this PP nonwoven fabric by the inkjet method, the time for continuous printing is long (for example, close to several tens of minutes). In this case, if printing is performed with one head unit and a discharge failure occurs, printing cannot be performed. If maintenance is performed to eliminate the ejection failure, printing stops during this time (the production line stops), and there is a problem that productivity is lowered.

  Therefore, it is desirable to use two or more head units and switch to another unit before discharge failure occurs to improve productivity.

  Further, since the transport speed of this type of PP nonwoven fabric is very fast (for example, several hundreds m / min), when printing on a PP nonwoven fabric transported at high speed by the ink jet method, printing at a considerably high frequency is required. Become. Furthermore, since the discharge droplet size of the head is large (around 80 pl), it is possible that high-frequency printing with one head may cause problems even in the range where continuous discharge is guaranteed. If possible, high-frequency printing will continue. It is desirable to reduce time.

  Conventionally, as an ink jet recording apparatus having a plurality of head units, there are those described in Patent Documents 1 to 3.

  In the ink jet recording apparatuses described in Patent Documents 1 to 3, a plurality of head units are arranged along the conveyance direction of the recording medium, respectively, and the plurality of head units can be independently maintained during a recording operation. The image printing operation is not interrupted during the maintenance process.

  Patent Document 1 also describes that two line heads are used simultaneously to record an image (claim 12, paragraph [0050] of Patent Document 1). That is, during normal image recording operation, two line heads are used together to form a plurality of line images at the same time, thereby enabling higher-speed image recording.

JP 2004-268511 A JP 2009-6665 A Special table 2008-516807 gazette

  In the invention described in Patent Document 1, the two line heads can be maintained independently, so that the image printing operation is not interrupted even during the maintenance processing of the head unit. By using two line heads at the same time, high-speed printing can be supported. However, in order to enable high-speed printing, if an image is printed by dividing each line sequentially by two line heads, odd lines There is a possibility that the image of the image and the image of the even line are greatly shifted and the image quality is deteriorated.

  Also, since the two line heads are independently moved between the maintenance position and the printing position for maintenance processing, the positioning accuracy of the two line heads can be increased when using the two line heads simultaneously. Although it is necessary to increase the positioning error of the two line heads, the nozzle head direction (main scanning direction) and the recording medium transport direction (sub-scanning direction) of the line head are within a range smaller than the dot pitch. It is very difficult to do.

  The inventions described in Patent Documents 2 and 3 can prevent the image printing operation from being interrupted during the maintenance process of the head unit as in the invention described in Patent Document 1, but one head unit is always provided. Since printing is performed only with one head unit, and printing is always performed by one head unit, the apparatus is wasted correspondingly. Furthermore, the time during which high-frequency printing is continuously performed by one head unit becomes longer, and the possibility of occurrence of a malfunction increases.

  The present invention has been made in view of such circumstances, and when printing an image on a recording medium for a long time, it is possible to prevent the occurrence of problems of a plurality of head units and to reduce the load on each head unit. It is an object of the present invention to provide an ink jet recording apparatus and method and a method for manufacturing a sanitary product that can reduce image quality and prevent deterioration in image quality.

  In order to achieve the above object, an ink jet recording apparatus according to an aspect of the present invention is a plurality of head units that perform printing by ejecting ink onto a recording medium, and are arranged along the conveyance direction of the recording medium. A plurality of head units, a unit moving mechanism for individually moving the plurality of head units between a printing position for printing on the recording medium and a maintenance position for performing maintenance, and the plurality of head units at the printing position. The first operation mode for holding and performing the printing operation for the first period and at least one of the plurality of head units is retracted to the maintenance position, and the remaining head units are held at the printing position for the second period. Including a second operation mode for performing the printing operation, and the first operation mode and the second operation mode are alternately repeated. First control means for controlling the movement mechanism, and a first control means for controlling the unit movement mechanism so that the plurality of head units sequentially move to the maintenance position corresponding to the second operation mode; A maintenance means for maintaining the retracted head unit, and a plurality of head units held at the print position during the first period of the first operation mode. A second control for performing a first print control for performing a print operation and a second print control for performing a print operation for the remaining head unit held at the print position during the second period of the second operation mode. When at least one image is printed on the recording medium by the plurality of head units held at the print position, the image is printed. And it includes a second control means for printing an image by sequentially allocating the plurality of head units in each printing region.

  According to one aspect of the present invention, a first operation mode in which a plurality of head units are held at a printing position and a printing operation is performed for a first period, and at least one of the plurality of head units is placed in a maintenance position. The second operation mode in which the remaining head unit is held at the printing position and the printing operation is performed for the second time is alternately repeated. Each time the operation mode is switched to the second operation mode, the second operation mode is sequentially withdrawn to the maintenance position. Maintenance of the head unit is performed, and even when an image is printed on a recording medium for a long time, occurrence of problems of a plurality of head units is prevented in advance. Further, during the first period of the first operation mode, printing is performed by a plurality of head units held at the printing position, the load on each head unit is reduced, and high-frequency printing is performed by the head unit in the second operation mode. It is possible to shorten the time for continuous execution. Further, when images are continuously printed on a recording medium by a plurality of head units held at the printing position, a plurality of head units are assigned to each printing area where at least one image is printed so as to print the images. Therefore, an image printed for each print area is printed by only one head unit, and a good image can be printed without being affected by the positioning accuracy of the print position of each head unit. Can do.

  In the ink jet recording apparatus according to another aspect of the present invention, the ejection performance of the head unit by the maintenance unit of the head unit moved to the maintenance position during the second period during the second period of the second operation mode. It is preferable that the time is from the start of the operation for recovering to the end of the operation for recovering. Thereby, the 2nd period of the 2nd operation mode can be made into the shortest time.

  In the ink jet recording apparatus according to still another aspect of the present invention, when the number of the plurality of head units is n and the maintenance cycle for maintaining each head unit is T, the first control means includes the n head units. It is preferable to control the unit moving mechanism so as to sequentially move to the maintenance position every time T / n time elapses. Thereby, a plurality of head units can be maintained at equal time intervals.

  In the inkjet recording apparatus according to still another aspect of the present invention, the interval in the conveyance direction of the recording medium of the plurality of head units held at the printing position is an integral multiple of the length in the conveyance direction of one printing area of the recording medium. It is preferable that As a result, printing can be performed by transmitting the same print data to each head unit as print data for printing with a plurality of head units, and the cost of the system can be reduced.

  In the ink jet recording apparatus according to still another aspect of the present invention, each head unit of the plurality of head units is a plurality of line heads that eject ink of the same color, in a direction intersecting with the conveyance direction of the recording medium. And a plurality of line heads arranged so that the nozzles of the respective line heads coincide with the transport direction, and the first print control and the second print control by the second control means are The line image in the raster image corresponding to the image to be printed on the recording medium is preferably printed by being shared by a plurality of line heads. As a result, it is possible to prevent the nozzles in the direction that coincides with the conveying direction of the plurality of line heads from being continuously operated, and as a result, the printing frequency for one line is increased compared to the frequency for driving the nozzles. (That is, printing at a high frequency).

  In the ink jet recording apparatus according to still another aspect of the present invention, the recording medium is preferably a nonwoven fabric, and the ink is preferably mixed with a member that improves the fixing property with the nonwoven fabric. In general, since non-woven fabrics are difficult to fix ink, it is preferable that ink is mixed with a member that improves fixability with non-woven fabrics.

  In the ink jet recording apparatus according to still another aspect of the present invention, the plurality of head units are disposed in the middle of a sanitary product production line made of nonwoven fabric. In the above production line, even when the nonwoven fabric is continuously conveyed for a long time, an image can be printed satisfactorily.

  An inkjet recording method according to still another aspect of the present invention includes a step of moving a plurality of head units that perform printing by ejecting ink onto a recording medium to respective printing positions along a conveyance direction of the recording medium; A plurality of head units at a printing position, and a first printing step for performing a printing operation for each of the first period; and at least one of the plurality of head units located at the printing position after the first period has elapsed. The step of moving to the maintenance position, the second printing step of causing the remaining head units other than the head unit moved to the maintenance position to perform the printing operation for the second period, and the maintenance of the head unit moved to the maintenance position are performed. And a maintenance process, repeating the first printing process and the second printing process, and a second period The head units to be moved to the maintenance position are sequentially switched, and when a plurality of continuous images are sequentially printed in the recording medium conveyance direction, the plurality of head units held at the printing position are sequentially placed for each unit length to be printed. The image is assigned and printed.

  In the ink jet recording method according to still another aspect of the present invention, the second period is recovered after starting the operation for recovering the ejection performance of the head unit moved to the maintenance position during the second period. It is preferable that it is a time until the operation for making it end.

  In the ink jet recording method according to still another aspect of the present invention, each head unit of the plurality of head units is a plurality of line heads that eject ink of the same color, in a direction intersecting with the conveyance direction of the recording medium. And a plurality of line heads arranged so that the nozzles of the respective line heads coincide with the carrying direction, and the first printing step and the second printing step print on the recording medium. It is preferable that the line image in the raster image corresponding to the image is printed by being shared by a plurality of line heads.

  In the ink jet recording method according to still another aspect of the present invention, the recording medium is preferably a nonwoven fabric, and the ink is preferably mixed with a member that improves the fixability with the nonwoven fabric.

  In the ink jet recording method according to still another aspect of the present invention, the plurality of line heads are disposed in the middle of a sanitary product production line using a nonwoven fabric as a material.

  In the method for manufacturing a sanitary article according to still another aspect of the present invention, an image is recorded on the nonwoven fabric by the inkjet recording method.

  According to the present invention, the first operation mode in which the plurality of head units are held at the printing position and the printing operation is performed for the first period, and at least one of the plurality of head units is retracted to the maintenance position, The second operation mode in which the remaining head unit is held at the printing position and the printing operation is performed for the second time is alternately repeated, and the head unit maintenance is sequentially retracted to the maintenance position each time the operation mode is switched to the second operation mode. Thus, it is possible to print an image on a recording medium for a long time without interrupting printing, and to prevent the occurrence of problems in a plurality of head units.

  In addition, during the first period of the first operation mode, printing is performed by a plurality of head units held at the printing position, so that the load on each head unit can be reduced and only one head unit can be used. The time for continuously performing high-frequency printing can be shortened. Furthermore, when printing multiple images that are continuous in the transport direction of the recording medium with multiple head units that are held at the print position, the multiple head units are assigned sequentially for each unit length to be printed. As a result, an image printed on a unit-length recording medium is printed by only one head unit, and is not affected by the positioning accuracy of the print position of each head unit. Can be printed.

1 is a schematic configuration diagram of a main part of a first embodiment of an ink jet recording apparatus according to the present invention. FIG. 1 is a plan view of the ink jet recording apparatus shown in FIG. Enlarged view of the main part of the nozzle part of three line heads that eject black (K) ink The figure which shows an example of the image (picture) printed on a nonwoven fabric The figure which shows four operation states of two head units A and B The figure which shows an example of the arrangement | positioning space | interval of the two head units A and B of a printing position. Timing chart showing printing operations in the first operation mode and the second operation mode of the two head units A and B Block diagram showing schematic configuration of control system of inkjet recording apparatus A flowchart showing a printing operation and a maintenance operation by the ink jet recording apparatus according to the first embodiment. Timing chart showing printing operation and maintenance operation of two head units A and B A flowchart showing a printing operation and a maintenance operation by the ink jet recording apparatus of the second embodiment. Timing chart showing print operation and maintenance operation of head units A, B and C 7 is a flowchart showing a modification of the printing operation and the maintenance operation by the ink jet recording apparatus of the second embodiment. Timing chart showing modified examples of printing operation and maintenance operation of head units A, B, and C

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of an ink jet recording apparatus and method and a sanitary product manufacturing method according to the present invention will be described below with reference to the accompanying drawings.

[Schematic configuration of inkjet recording apparatus]
FIG. 1 and FIG. 2 are schematic configuration diagrams of the main part of the first embodiment of the ink jet recording apparatus according to the present invention, FIG. 1 is a side view of the ink jet recording apparatus, and FIG. 2 is a plan view of the ink jet recording apparatus. is there.

  In FIG. 1, an ink jet recording apparatus 100 is an ink jet recording apparatus using a PP (polypropylene) nonwoven fabric 102 of a raw material such as a disposable diaper, a sanitary mask, and a sanitary product as a recording medium. Head units A and B are disposed between the rollers 110 and 112.

  Press rollers 120 and 124 for preventing the nonwoven fabric 102 from floating are in contact with the rollers 110 and 112. The roller 112 is provided with a speed sensor 174 for detecting the conveyance speed of the nonwoven fabric 102.

  In the nonwoven fabric 102, one roll has a length of several kilomails and is continuously conveyed at a high speed of several hundred m / min.

As shown in FIG. 2, the head units A and B have the same configuration, and each head unit includes a plurality (three) of line heads that eject ink of the same color (ink). In this embodiment, from the upstream side in the transport direction of the nonwoven fabric 102, black line head 106K _a for ejecting ink _{(K), 106K b, 106K} c, yellow (Y) ink line heads 106Y _a for ejecting the, 106Y _b, 106Y _c, ink line head ejects 106M _a magenta _{(M), 106M b, 106M} c, and the ink line head for ejecting cyan (C) 106C _a, and a 106C _b, 106C _c.

  A maintenance zone 130 for performing maintenance of the head units A and B is provided in parallel with the conveyance path of the nonwoven fabric 102.

  Each head unit A, B is independently shown between a printing position for printing on the nonwoven fabric 102 (position shown in FIG. 2) and a maintenance position in the maintenance zone 130 (not shown). It can be moved by 8).

  The unit moving mechanism 142 transmits a driving force to the head units A and B individually via a belt, a gear train, and the like, and a guide member that supports the head units A and B so as to be movable in the left-right direction in FIG. And it can comprise with the well-known drive part etc. which are moved along a guide member.

  The maintenance zone 130 is provided with a maintenance unit 140 (FIG. 8) that performs maintenance of the head units A and B. The maintenance unit 140 is a part that performs a required maintenance process for the head unit A or B that has been retreated to the maintenance zone 130, and the preliminary ejection and ink ejection surface of the line head that constitutes the head unit are treated with the processing liquid. A process such as wiping for wiping with a wiper with a wiper and nozzle suction is performed to prevent the occurrence of a discharge abnormality or to quickly recover from a discharge abnormality.

FIG. 3 is an enlarged view of a main part of the nozzles of the line heads 106K _a , 106K _b , and 106K _c that discharge black (K) ink.

As shown in FIG. 3, the line heads 106K _a , 106K _b , and 106K _c are arranged in parallel along a direction that intersects the conveyance direction of the nonwoven fabric (in this embodiment, an orthogonal method), and the line heads 106K _a , 106K _b , 106K _c nozzles (1, 2, 3,...) Are arranged so as to coincide with the transport direction. Note that line heads corresponding to other colors are also arranged in the same manner. In the embodiment shown in FIG. 3, a plurality of nozzles are arranged in a line along the longitudinal direction of the line head. However, a configuration in which a plurality of nozzles are arranged in two lines in the same direction is also applicable.

  A desired color image can be drawn on the nonwoven fabric 102 by discharging the ink of each color of KYMC from the nozzles at an appropriate timing when the nonwoven fabric 102 passes immediately below each line head of the head units A and B. .

  Further, the ink of each color used in the ink jet recording apparatus 100 of this embodiment is a mixture of members that improve the fixing property with the nonwoven fabric 102. This is because the PP repels ink, so that the fixing property with the PP is improved. For example, there are known inks that maintain fixability by containing a polymerizable compound, a polymerization initiator, or the like in the ink (JP 2006-312711 A, JP 2007-238648 A).

  FIG. 4 shows an example of an image (picture) drawn on the nonwoven fabric 102 by the inkjet recording apparatus 100. As shown in FIG. 4, the inkjet recording apparatus 100 repeatedly draws the same picture for each print region of the length L of one product assigned to the nonwoven fabric 102, but when drawing a picture for one product, Twelve line heads (see FIG. 2) are used.

Here, when the printing cycle of a line image for one line is Δt, the pitch between dots in the conveyance direction of the image printed on the nonwoven fabric 102 is Δp (μm), and the conveyance speed of the nonwoven fabric 102 is V (m / second), Δt = Δp / V (10 ⁻⁶ seconds). As described above, since the conveyance speed V of the nonwoven fabric 102 is very fast, the printing frequency for one line becomes high (that is, printing at a high frequency).

  On the other hand, as shown in FIG. 3, since there are three line heads arranged so that the nozzles coincide with the transport direction and eject ink of the same color, the ink is ejected from three nozzles having the same transport direction. The drop period can be set to be three times or more the print period Δt of the line image for one line. Accordingly, even when ink having a large droplet size (around 80 pl) is ejected, each nozzle can be driven sufficiently and high-frequency printing can be performed.

The line head 106K _b as shown in FIG. 3 is arranged only on the downstream side of the feeding direction distance h than the line head 106K _a line head 106K _c, only the feeding direction distance 2h than the line head 106K _a The print timing when the same line image is shared by the nozzles of the three line heads 106K _a, 106K _b , and 106K _c is printed with respect to the timing at the line head 106K _a . The timings of the line heads 106K _b and 106K _c are delayed by a delay time corresponding to the distance h and the distance 2h, respectively.

In the above example, the line heads 106K _a , 106K _b , and 106K _c that eject black ink are described. However, the line heads 106Y _a , 106Y _b , 106Y _c , and line heads 106M _a , 106M corresponding to other colors are described. _b, 106M _c, and the line head 106C _a, 106C _b, by 106C _c also driven in the same manner, it is possible to print a color image at a high speed a nonwoven fabric 102.

<Inkjet recording method>
Next, the principle of the ink jet recording method according to the present invention will be described.

  5A to 5D show the four operation states of the head units A and B, respectively.

  FIG. 5A shows a state in which the head unit B located in the maintenance zone 130 moves (returns) to the printing position, and an image is printed on the nonwoven fabric 102 by the two head units A and B. In this state, when printing is performed for a certain time (for example, 4 to 5 minutes), the head unit A is moved (retracted) from the printing position to the maintenance position in the maintenance zone 130 as shown in FIG. While performing maintenance of the head unit A, during the maintenance period of the head unit A, printing is continuously performed by the head unit B alone.

  When the maintenance of the head unit A is completed, the head unit A is moved to the printing position as shown in FIG. 5C, and printing by the two head units A and B is performed again. When printing is performed for a certain period of time in this state, the head unit B is retracted from the printing position to the maintenance position in the maintenance zone 130 as shown in FIG. During the maintenance period B, printing is continued with the head unit A alone.

  When the maintenance of the head unit B is completed, the head unit B is moved to the printing position as shown in FIG. 5A, and printing by the two head units A and B is performed again.

  By sequentially repeating the above four operation states of the head units A and B, an image can be printed on the nonwoven fabric 102 continuously for a long time.

  Here, an operation state in which printing is performed by two head units A and B (FIGS. 5A and 5C) and an operation state in which printing is performed by one head unit of head unit A or B (FIG. 5). (B), (d)) differs from the driving method of the head unit. Here, the operation mode of the operation state in which the printing by the two head units A and B is performed is referred to as a “first operation mode”, and the operation state in which the printing by only one head unit of the head unit A or B is performed. The operation mode is referred to as “second operation mode”, and the first and second operation modes will be described in detail below.

  As shown in FIG. 6, when the head units A and B are held at the print positions, the distance in the transport direction of the nonwoven fabric 102 of the head units A and B is the length of one product assigned to the nonwoven fabric 102. It is arranged so as to be approximately an integral multiple of the length L (in the embodiment shown in FIG. 6, 3 times 3L).

  In FIG. 6, an image (picture) indicated by a solid line is printed in a printing area for each product of the nonwoven fabric 102 or indicates an image during printing, and an image indicated by a broken line is displayed in the printing area for each product of the nonwoven fabric 102. An image to be printed is shown. Symbols A and B in the image indicate which of the head units A and B is printed or will be printed.

  As shown in FIG. 7A, in the first operation mode, assuming that the conveyance time of one product length L is t, the two head units A and B perform a printing operation and a printing pause at every time t. repeat. Here, since the interval between the head units A and B is an integral multiple (3 times) of the product length L, when printing with the two head units A and B, Printing can be performed by sending the same print data at the same timing.

  As shown in FIG. 6, the two head units A and B individually print an image in a print area for each product during the printing operation at time t.

  As shown in FIG. 6, the distance between the two head units A and B is an odd multiple (three times) of the product length L, so that the two head units A and B print simultaneously at every time t. By repeating the operation and the printing pause, images are continuously printed on the nonwoven fabric 102 passing through the downstream head unit A at intervals of the product length L.

  As described above, when printing an image on the nonwoven fabric 102 with the two head units A and B, the head unit A or B is assigned to each print region of the product so that the image is printed. Printing can be performed without deterioration in image quality as compared with the case where printing is performed by sharing the head units A and B for each line. Further, the positioning accuracy of the print positions of the two head units A and B in the main scanning direction and the sub-scanning direction is not required to be within the dot pitch, and the cost of the unit moving mechanism 142 can be reduced.

  In the first operation mode, the printing operation by the two head units A and B is performed. Since each head unit alternately repeats the printing operation and the printing pause, the time for continuous high-frequency printing is set. The load on each head unit can be reduced.

  On the other hand, as shown in FIG. 7B, in the second operation mode, only one head unit of the head unit A or B performs the printing operation continuously (even during the above-described printing pause period). Thereby, an image can be continuously printed at intervals of the length L of the product. Since the first operation mode and the second operation mode are alternately repeated, the time for continuously performing high-frequency printing with only one head unit can be shortened. In addition, during the period of the first operation mode, maintenance is performed on other head units that are not performing the printing operation.

  Further, the switching control is performed as follows so that the printing of the image on the nonwoven fabric 102 is not interrupted when switching from the first operation mode to the second operation mode.

  In FIG. 6, when the head unit A on the downstream side of the nonwoven fabric 102 is retracted to the maintenance position, the head unit B operating in the first operation mode from the predetermined time before the printing by the head unit A is completed is changed to the first unit. The operation mode is switched to 2 so that the image is already printed in the print area to be printed by the head unit A, which reaches the print position of the head unit A.

  On the other hand, when the head unit B on the upstream side of the nonwoven fabric 102 is retracted to the maintenance position, the image printed immediately before the head unit B is retracted operates in the first operation mode after passing the print position of the head unit A. The head unit A is switched to the second operation mode.

  Similarly, when switching from the second operation mode to the first operation mode, the head units A and B perform switching with a time lag at the switching timing from the second operation mode to the first operation mode. That is, when returning the downstream head unit A to the printing position, the head unit B operating in the second operation mode is switched to the first operation mode early, and then the head unit A is switched to the first operation mode. Operate in the operation mode. When the upstream head unit B is returned to the printing position, the head unit B is operated in the first operation mode, and the head unit A operating in the second operation mode after a predetermined time has elapsed. Switch to operation mode 1.

  Thereby, the printing of the image on the nonwoven fabric 102 can be prevented from being interrupted when switching between the first operation mode and the second operation mode. Needless to say, the switching timing is different depending on the distance between the head units A and B.

[Configuration of control system of inkjet recording apparatus]
Next, the control system of the inkjet recording apparatus 100 will be described. FIG. 8 is a block diagram illustrating a schematic configuration of a control system of the inkjet recording apparatus 100.

  In addition to the head units A and B, the maintenance unit 140 (maintenance unit), and the unit moving mechanism 142 described above, the inkjet recording apparatus 100 includes a communication interface 170 and a system control unit 172 (first control unit and second control unit). Means), a speed sensor 174, an image processing unit 176, a head driving unit 178, and a RAM (Random Access Memory) 180 and a ROM (Read Only Memory) 182.

  The communication interface 170 is an interface unit that receives raster image data sent from the host computer 184. As the communication interface 170, a serial interface such as USB (Universal Serial Bus) may be applied, or a parallel interface such as Centronics may be applied. The communication interface 170 may include a buffer memory (not shown) for speeding up communication.

  The system control unit 172 includes a central processing unit (CPU) and its peripheral circuits, and functions as a control device that performs overall control of the inkjet recording apparatus 100 according to a predetermined program, and also functions as an arithmetic device that performs various calculations. Further, it functions as a memory controller for the RAM 180 and the ROM 182.

  That is, the system control unit 172 controls each unit such as the communication interface 170 and the head driving unit 178, performs communication control with the host computer 184, read / write control of the RAM 180 and ROM 182 and the like, and controls each unit described above. A control signal is generated.

  Image data sent from the host computer 184 is taken into the ink jet recording apparatus 100 via the communication interface 170, and is subjected to predetermined image processing by the image processing unit 176.

  The image processing unit 176 has a signal (image) processing function for performing processing such as various processes and corrections for generating a signal for print control from the image data, and drives the generated print data (dot image data) to the head. It is a control unit supplied to the unit 178.

  When required signal processing is performed in the image processing unit 176, the amount of ink ejected from the line heads 106 of the head units A and B via the head driving unit 178 based on the print data (halftone image data) ( The droplet ejection amount) and the discharge timing are controlled.

  Thereby, a desired dot size and dot arrangement are realized. The head driving unit 178 may include a feedback control system for keeping the driving conditions of the line heads 106 of the head units A and B constant.

  The speed sensor 174 detects the conveyance speed of the nonwoven fabric 102 and outputs a detection signal to the system control unit 172.

  The system control unit 172 controls the ejection timing of ink ejected from the line heads 106 of the head units A and B via the head driving unit 178 based on the conveyance speed of the nonwoven fabric 102 detected by the speed sensor 174.

  In addition, the system control unit 172 has a timer circuit, and alternately switches between the first operation mode and the second operation mode at every predetermined time counted by the timer circuit, and performs printing by the head units A and B. Control.

  Further, the system control unit 172 controls the unit moving mechanism 142 when switching between the first operation mode and the second operation mode, and moves the head unit A or B between the printing position and the maintenance position. During the second operation mode, the maintenance unit 140 causes the maintenance unit 140 to perform maintenance of the head unit retracted to the maintenance position.

  The RAM 180 functions as a temporary storage unit that temporarily stores image data input via the communication interface 170, a development area for various programs stored in the ROM 182, and a calculation work area for the CPU (for example, the image processing unit 176). As a work area).

  The ROM 182 stores programs executed by the CPU of the system control unit 172, various data necessary for control of each unit of the apparatus, control parameters, and the like, and data is read and written through the system control unit 172. The ROM 182 is not limited to a memory made of a semiconductor element, and a magnetic medium such as a hard disk may be used. Alternatively, a removable storage medium that includes an external interface may be used.

  The parameter storage unit 190 stores various control parameters necessary for the operation of the inkjet recording apparatus 100. The system control unit 172 appropriately reads out parameters necessary for control and updates (rewrites) various parameters as necessary.

  The program storage unit 192 is a storage unit that stores a control program for operating the inkjet recording apparatus 100. When the system control unit 172 (or each unit of the device) executes control of each unit of the device, a necessary control program is read from the program storage unit 192, and the control program is appropriately executed.

<First Embodiment>
Next, a printing operation and a maintenance operation by the inkjet recording apparatus 100 according to the first embodiment having the above configuration will be described.

  FIG. 9 is a flowchart showing a printing operation and a maintenance operation by the ink jet recording apparatus 100, and will be described below with reference to the flowchart of FIG.

[Step S10]
Switching to the first operation mode causes printing by the two head units A and B. Then, when a predetermined time t ₁ (for example, 4 to 5 minutes) has elapsed from the start of printing, the process proceeds to step S12 in order to perform maintenance of the head unit A.

[Step S12]
Switching to the second operation mode causes printing by only one head unit B and starts maintenance of the head unit A. When a predetermined time t ₂ (for example, 2 to 3 minutes) elapses from the start of maintenance, the maintenance ends, printing by the head unit A becomes possible, and the process proceeds to step S14.

[Step S14]
Switching to the first operation mode causes printing by the two head units A and B. Then, when the time t ₁ elapses from the start of printing, in order to perform the maintenance of the head unit B, shifts to step S16.

[Step S16]
Switching to the second operation mode causes printing by only one head unit A and starts maintenance of the head unit B. When the time t ₂ has elapsed from the maintenance start, the maintenance is finished, allows printing by the head unit B, it shifts to step S10.

  The processing from step S10 to step S16 is repeatedly executed until all printing on the nonwoven fabric 102 is completed.

  FIG. 10 is a timing chart showing the printing operation and maintenance operation of the head units A and B.

As shown in FIG. 10A, the period during which the two head units A and B perform the printing operation (first operation mode period) is t ₁ , and the period during which only one head unit performs the printing operation (second operation mode). When the period) and the t _2, when the first operation mode in a period printing operation time t ₁ is carried out, then a second operation mode in a period printing operation time t ₂ is performed, which is alternately repeated It is. In the second operation mode, the printing operation is performed with only one head unit A or B, while the other head units are maintained during that time.

Here, as shown in FIGS. 10B and 10C, the printing time t2 in the _second operation mode and the operation for recovering the ejection performance of the head unit A or B by the maintenance unit 140 are performed. The time from the start to the end of the recovery operation is substantially the same. When maintenance is completed and printing is possible, the printer immediately returns to the printing position and printing in the first operation mode is performed. Resumed.

Now, assuming that the maintenance cycle of the head units A and B is T, A and the head unit B enter maintenance alternately by shifting the time by T / 2 hours (FIGS. 10B and 10C). Further, the first and the printing time t1 in the operating mode printing time t ₂ and the total time of the second mode of operation, the time T / 2.

In FIG 10, although the printing time t ₁ in the first operation mode and the printing time t ₂ in the second operation mode is set to approximately the same time, the two head units A, B are operated It is preferable that the printing time t ₁ in the first operation mode is longer than the printing time t ₂ in the second operation mode in which only one head unit operates.

<Second Embodiment (Part 1)>
The ink jet recording apparatus according to the second embodiment includes three head units A, B, and C. The ink jet recording apparatus according to the second embodiment differs from the first embodiment in the number of head units, and as a result, the printing operation and the maintenance operation by the ink jet recording apparatus are different.

  FIG. 11 is a flowchart showing a printing operation and a maintenance operation by the ink jet recording apparatus according to the second embodiment, and will be described below with reference to the flowchart of FIG.

[Step S20]
Switching to the first operation mode in which the three head units A, B, and C perform printing operation causes the three head units A, B, and C to perform printing. Then, when the predetermined time t ₁ has elapsed from start of printing, in order to perform the maintenance of the head unit A, shifts to step S22.

[Step S22]
Switch to the second operation mode in which two of the three head units A, B, and C perform the printing operation, cause printing by the two head units B and C, and start the maintenance of the head unit A . When the time t ₂ has elapsed from the maintenance start, the maintenance is finished, allows printing by the head unit A, it shifts to step S24.

[Step S24]
The mode is switched to the first operation mode, and printing by the three head units A, B, and C is performed. Then, when the time t ₁ elapses from the start of printing, in order to perform the maintenance of the head unit B, shifts to step S26.

[Step S26]
Switching to the second operation mode causes the two head units A and C to perform printing, and maintenance of the head unit B is started. When the time t ₂ has elapsed from the maintenance start, the maintenance is finished, allows printing by the head unit B, it shifts to step S28.

[Step S28]
The mode is switched to the first operation mode, and printing by the three head units A, B, and C is performed. Then, when the time t ₁ elapses from the start of printing, in order to perform the maintenance of the head unit C, shifts to step S30.

[Step S30]
The operation mode is switched to the second operation mode, printing is performed by the two head units A and B, and maintenance of the head unit C is started. When the maintenance start time t ₂ has elapsed, the maintenance is finished, it allows printing by the head unit C, shifts to step S32.

[Step S32]
The mode is switched to the first operation mode, and printing by the three head units A, B, and C is performed. Then, when the time t ₁ elapses from the start of printing, in order to perform the maintenance of the head unit A, shifts to step S22.

  Thereafter, the processing from step S22 to step S32 is repeatedly executed until all printing on the nonwoven fabric 102 is completed.

  FIG. 12 is a timing chart showing the printing operation and maintenance operation of the head units A, B and C.

As shown in FIG. 12A, the period during which the three head units A, B, and C perform the printing operation (period of the first operation mode) is t ₁ , and the period during which the two head units perform the printing operation (second operation). When the mode of the period) is defined as t _2, when the first operation mode in a period printing operation time t ₁ is carried out, then the period printing operation time t ₂ in the second operation mode is performed, which is alternately Repeated. In the second operation mode, any one of the three head units A, B, and C is maintained (FIGS. 12B, 12C, and 12D), but the remaining head units are maintained. The printing operation is continuously performed by the head unit.

Now, assuming that the maintenance cycle of the head units A, B, and C is T, the head units A, B, and C enter maintenance in order by shifting the time by T / 3 hours (FIGS. 12B and 12C). ), (D)). Further, the first and the printing time t1 in the operating mode printing time t ₂ and the total time of the second mode of operation, the T / 3 hours.

  In the second embodiment, since the two head units perform the printing operation even in the second operation mode, the two head units are driven as in the first embodiment (as shown in FIG. 7A). In the first operation mode, the print pause period can be made longer than that in the second operation mode.

<Second Embodiment (No. 2)>
Next, modified examples of the printing operation and the maintenance operation by the ink jet recording apparatus including the three head units A, B, and C will be described.

  FIG. 13 is a flowchart showing a modification of the printing operation and the maintenance operation by the ink jet recording apparatus of the second embodiment, and will be described below with reference to the flowchart of FIG.

[Step S40]
First, the three head units A, B, and C are printed. Then, when a predetermined time t has elapsed from the start of printing, the process proceeds to step S42 to perform maintenance of the head unit A.

[Step S42]
Switch to the first operation mode in which two of the three head units A, B, and C perform the printing operation, cause printing by the two head units B and C, and start the maintenance of the head unit A . When the time t ₁ has elapsed from the maintenance start, in order to perform the maintenance of the head unit B, shifts to step S44.

[Step S44]
Switch to the second operation mode in which only one of the three head units A, B, and C performs the printing operation, the printing is performed only by the head unit C, and the maintenance of the head unit B is started. When the time t ₂ from the maintenance start of the unit B has elapsed, the maintenance of the head unit a is completed, enables printing by the head unit a, it shifts to step S46.

[Step S46]
Switching to the first operation mode, printing by the two head units A and C is performed, and when the time T / 3 (= t ₁ + t ₂ ) has elapsed from the start of the maintenance of the head unit B, the head unit C should be maintained. Then, the process proceeds to step S48.

[Step S48]
Switched to the second operation mode, causes performed only by the print head unit A, to initiate maintenance of the head unit C, the time t ₂ from the maintenance start of the head unit C has elapsed, the maintenance of the head unit B is completed Then, printing by the head unit B becomes possible, and the process proceeds to step S50.

[Step S50]
Switching to the first operation mode, printing by the two head units A and B is performed, and when time T / 3 has elapsed from the start of maintenance of the head unit C, the process proceeds to step S52 in order to perform maintenance of the head unit A.

[Step S52]
Switched to the second operation mode, causes performed only by the print head unit B, to start the maintenance of the head unit A, the time t ₂ from the maintenance start of the head unit A has elapsed, the maintenance of the head unit B is completed Printing by the head unit B becomes possible, and the process proceeds to step S42.

  Thereafter, the processing from step S42 to step S52 is repeated until all printing on the nonwoven fabric 102 is completed.

  FIG. 14 is a timing chart showing a modification of the printing operation and maintenance operation of the head units A, B, and C.

As shown in FIG. 14 (a), t _{1 is} a period during which two of the three head units A, B, and C perform a printing operation (period of the first operation mode), and only one head unit performs printing. Assuming that the operation period (second operation mode period) is t ₂ , if the printing operation is performed for the period of time t ₁ in the first operation mode, then the printing operation is performed for the period of time t ₂ in the second operation mode. This is repeated alternately.

  In the first operation mode, one of the three head units A, B, and C that is not performing the printing operation is under maintenance, and in the second operation mode, the three head units A, The remaining two head units of B and C that are not performing printing are under maintenance.

Now, assuming that the maintenance cycle of the head units A, B, and C is T, the head units A, B, and C enter maintenance in order by shifting the time by T / 3 hours (FIGS. 14B and 14C). ), (D)). Further, the first and the printing time t1 in the operating mode printing time t ₂ and the total time of the second mode of operation, the T / 3 hours.

  According to the modification of the second embodiment, one or two of the three head units A, B, and C are in maintenance at all times, so that the maintenance period of one head unit is maintained. Can be increased (one third (T / 3) or more of the maintenance period T).

[Others]
In the above embodiment, when printing an image by assigning a plurality of head units for each print area (print area of length L as shown in FIG. 4) corresponding to one product, Not only when printing is performed by assigning to a plurality of head units, but a case where an image within a length L straddling two adjacent products is printed by one head unit as shown in FIG. In the latter case, since an image in one product is printed by two head units, the continuity (image quality) of the boundary portion of the image printed by the two head units may be lowered. Is preferred. However, even in the latter case, the image quality may be deteriorated only at the boundary portion of the image printed by the two head units, and the boundary portion of the image to be printed is a flat image with a monochromatic solid surface. There is no problem if it is a part with no image.

  Further, when printing with a plurality of head units, the print area of each head unit is assigned for each length L corresponding to one product. However, the length is not limited to this, and the length corresponding to a plurality of products. You may make it allocate every (for example, length 2L of two products).

  Each head unit has three line heads that eject ink of the same color, and each line head has a plurality of line heads arranged so that the nozzles of each line head coincide with the sub-scanning direction. The number of line heads is not limited to this embodiment, and for example, one line head may be provided for each color.

  Furthermore, in this embodiment, the example of printing the same image for each non-woven fabric product conveyed at high speed has been described, but the present invention is also applicable to printing different images for each product or printing a continuous pattern. it can. The image to be printed is not limited to a color image, and may be a single color image.

  Furthermore, the number of head units is not limited to two or three in this embodiment, and may be two or more. Here, when the number of head units is n (n is a natural number of 2 or more) and the maintenance cycle for maintaining each head unit is T, the n head units are sequentially turned on every time T / n time elapses. Maintenance is preferred. Thereby, a plurality of head units can be maintained at equal time intervals.

  In addition, the present invention is not limited to printing on non-woven fabrics. For example, printing on other recording media such as plain paper, inkjet paper, coated paper, electrophotographic co-paper, cloth, porous film, polymer absorber, etc. Is also applicable.

  Furthermore, it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

100 ... ink jet recording apparatus, 102 ... _nonwoven, 106K a _~106C c _... line head, 130 ... maintenance zone, 140 ... maintenance unit, 142 ... unit moving mechanism, 172 ... system control unit, 174 ... speed sensor, 176 ... image processing Part, 178 ... head drive part, 180 ... RAM, 182 ... ROM, A, B, C ... head unit

Claims (13)

A plurality of head units that perform printing by ejecting ink onto a recording medium, the plurality of head units being arranged along a conveyance direction of the recording medium;
A unit moving mechanism for individually moving the plurality of head units between a printing position for printing on the recording medium and a maintenance position for performing maintenance;
A first operation mode in which the plurality of head units are held at the printing position and a printing operation is performed for a first period, and at least one of the plurality of head units is retracted to a maintenance position, and the remaining head units The unit moving mechanism is controlled so as to alternately repeat the first operation mode and the second operation mode. First control means for controlling the unit moving mechanism so that the plurality of head units sequentially move to a maintenance position corresponding to the second operation mode;
Maintenance means arranged at a maintenance position where the plurality of head units are retracted, and performing maintenance of the retracted head units;
A first print control for causing each of the plurality of head units held at the print position to perform a print operation during a first period of the first operation mode; and a second print mode during the second period of the second operation mode. And a second control means for performing a second print control for performing a printing operation on the remaining head unit held at the print position, wherein the plurality of head units held at the print position are continuously connected to the recording medium. A second control means for allocating the plurality of head units for each printing region where at least one image is printed and printing the image when printing an image;
An ink jet recording apparatus comprising:   The second period of the second operation mode starts the operation of the head unit moved to the maintenance position during the second period to restore the ejection performance of the head unit by the maintenance unit. The ink jet recording apparatus according to claim 1, wherein the time is a time from the start to the end of the operation for recovery.   Assuming that the number of the plurality of head units is n and the maintenance period for maintaining each head unit is T, the first control unit sequentially turns the n head units every time T / n time elapses. The ink jet recording apparatus according to claim 1, wherein the unit moving mechanism is controlled to move the unit to the maintenance position.   The interval in the conveyance direction of the recording medium of the plurality of head units held at the printing position is an integral multiple of the length in the conveyance direction of one printing area of the recording medium. The inkjet recording apparatus according to Item. Each head unit of the plurality of head units is a plurality of line heads that eject ink of the same color, and is arranged in parallel along a direction intersecting with the conveyance direction of the recording medium, and each of the line heads Having a plurality of line heads arranged so that the nozzles coincide with the transport direction;
The first printing control and the second printing control by the second control unit are configured to print a line image in a raster image corresponding to an image to be printed on the recording medium by the plurality of line heads. Item 5. The inkjet recording apparatus according to any one of Items 1 to 4. The recording medium is a nonwoven fabric,
The ink jet recording apparatus according to claim 1, wherein the ink is mixed with a member that improves fixability with the nonwoven fabric.   The inkjet recording apparatus according to claim 1, wherein the plurality of head units are arranged in the middle of a production line for sanitary goods made of nonwoven fabric. A step of moving a plurality of head units that perform printing by ejecting ink onto a recording medium to respective printing positions along a conveyance direction of the recording medium;
A first printing step of causing each of the plurality of head units at the printing position to perform a printing operation for a first period;
Moving at least one of the plurality of head units positioned at the print position to the maintenance position after the first period has elapsed;
A second printing step of causing the remaining head units other than the head unit moved to the maintenance position to perform a printing operation for a second period;
A maintenance step of performing maintenance of the head unit moved to the maintenance position,
While repeating the first printing step and the second printing step, the head units that are moved to the maintenance position during the second period are sequentially switched,
When images are continuously printed on the recording medium by the plurality of head units held at the printing position, the plurality of head units are sequentially assigned to each printing area where at least one image is printed, and the images are printed. An inkjet recording method.   The second period is the time from the start of the operation for recovering the ejection performance of the head unit moved to the maintenance position during the second period until the end of the operation for recovery. The inkjet recording method according to claim 8. Each head unit of the plurality of head units is a plurality of line heads that eject ink of the same color, and is arranged in parallel along a direction intersecting with the conveyance direction of the recording medium, and each of the line heads Having a plurality of line heads arranged so that the nozzles coincide with the transport direction;
10. The first printing step and the second printing step according to claim 8 or 9, wherein line images in a raster image corresponding to an image to be printed on the recording medium are shared by the plurality of line heads and printed. Inkjet recording method. The recording medium is a nonwoven fabric,
11. The ink jet recording method according to claim 8, wherein the ink is mixed with a member that improves fixability to the nonwoven fabric.   The inkjet recording method according to claim 11, wherein the plurality of line heads are disposed in the middle of a sanitary product production line made of a nonwoven fabric.   The said recording medium is a nonwoven fabric, The manufacturing method of the sanitary goods which records an image on the said nonwoven fabric with the inkjet recording method of any one of Claims 8-12.

Images