JP6199215B2 - Printing method for inkjet printing apparatus - Google Patents

Description

  The present invention relates to a printing method of an ink jet printing apparatus that prints an image on a printing medium by ejecting ink droplets onto the printing medium, and more particularly, to a technique for printing on a printing medium in which surface abnormality such as wrinkles or unevenness occurs. .

  Conventionally, as a method of this type, when a detection unit provided upstream of a printing unit that ejects ink droplets is provided and the unevenness of the printing paper is detected by the detection unit, the detected unevenness of the printing paper There is one that adjusts the ejection timing of ink droplets from the printing unit according to the interval with the printing unit (see, for example, Patent Document 1).

JP 2006-264074 A

However, the conventional example having such a configuration has the following problems.
That is, the conventional apparatus requires a step of detecting the unevenness of the printing paper by the detecting unit and a step of correcting the ejection timing after the detection, and thus has a problem that the control becomes complicated.

  By the way, in addition to surface abnormalities such as unevenness and seams, printing paper has surface abnormalities called cockling. This surface abnormality called cockling may occur, for example, when the printing paper stops for a certain period of time in a complicated conveyance path. Since the portion where such a surface abnormality has occurred may be a height exceeding the gap between the printing unit and the conveyance path, the surface abnormality portion may collide with the printing unit. Therefore, when the ejection timing is corrected by the conventional configuration, normal printing cannot be performed on the printing paper.

  The present invention has been made in view of such circumstances, and printing by an inkjet printing apparatus that can perform printing while preventing a surface abnormal portion of a print medium from colliding with a printing unit while being simple control. It aims to provide a method.

In order to achieve such an object, the present invention has the following configuration.
That is, the invention according to claim 1 is a printing method of an ink jet printing apparatus including an ink jet head that ejects ink droplets onto a print medium. The retreat is higher than the print position for printing on the print medium. Based on the parameters related to the ink-jet head retreat position moving step for moving the ink-jet head to a position and the occurrence position of the abnormal surface portion in the print medium, which has been input in advance, An avoidance conveyance step in which an abnormal portion conveys to a collision avoidance position where interference with the inkjet head can be avoided, an inkjet head printing position movement step in which the inkjet head is moved from the retracted position to a printing position, and the printing medium is conveyed. While ink droplets from the inkjet head It comprises a printing step of performing discharge to printing, the is characterized in.

  [Operation / Effect] According to the first aspect of the present invention, the inkjet head is moved to the retracted position (inkjet head retracted position moving step), and the print medium is transported to the collision avoidance position based on the previously input parameters. (Avoidance conveyance step). Then, the inkjet head is moved to the printing position (inkjet head printing position moving step), and printing is performed on the printing medium (printing step). Since the print medium is transported to the collision avoidance position based on the parameters inputted in advance, the abnormal portion of the surface of the print medium collides with the printing unit by simple control of transport to the predetermined position without using the detection means. Can be printed while preventing printing.

  In the present invention, a plurality of the inkjet heads are provided along the transport direction of the print medium, and the inkjet head retracting position moving step simultaneously raises the plurality of inkjet heads, In the printing position moving step, it is preferable that the ink jet head that has passed the abnormal surface portion is lowered in order.

  When a plurality of ink jet heads are provided, the ink jet heads that have passed through the abnormal surface portion are moved to the printing position in order, so that the ink jet heads that have moved can be printed in order. Therefore, it is possible to reduce the waste paper that is wasted print media.

  In the present invention, the avoidance conveyance step calculates a conveyance time to the collision avoidance position based on a distance from the position where the abnormal surface portion of the print medium is generated to the inkjet head, and only the conveyance time is calculated. It is preferable to transport the print medium.

  Since the transport time from the position where the abnormal surface occurs to the inkjet head and the transport speed to the collision avoidance position can be calculated, the print medium can be moved to the collision avoidance position only by transporting the transport time. Can do.

  In the present invention, it is preferable that the parameter is a type of a pre-processing apparatus for the print medium connected upstream.

  The surface printing device connected to the upstream side of the back surface printing device or the undercoat liquid coating device connected to the upstream side of the printing device knows in advance where the abnormal surface portion is structurally generated. Yes. Therefore, the model of the pretreatment device can be used as a parameter.

  According to the printing method of the inkjet printing apparatus which concerns on this invention, it can do.

1 is an overall configuration diagram illustrating a schematic configuration of an inkjet printing system according to an embodiment. It is a figure which shows schematic structure of a surface printing apparatus. It is a figure which shows schematic structure of a back surface printing apparatus. It is a figure where it uses for description of raising / lowering of a print head. It is a figure where it uses for description of a collision avoidance position. 6 is a flowchart illustrating an operation of print processing. It is a schematic diagram which shows the operation | movement at the time of a printing start. It is a schematic diagram which shows the state which moved to the collision avoidance position of the print head (K). It is a schematic diagram which shows the example of a movement until the printing start of a print head.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is an overall configuration diagram illustrating a schematic configuration of an inkjet printing system according to an embodiment. 2 is a diagram illustrating a schematic configuration of the front surface printing apparatus, and FIG. 3 is a diagram illustrating a schematic configuration of the back surface printing apparatus.

  The inkjet printing system 1 includes a paper feeding unit 3, a front surface printing device 5, a reversing device 7, a back surface printing device 9, and a paper discharge unit 11.

  The paper supply unit 3 holds the roll-shaped continuous paper WP so as to be rotatable about a horizontal axis, and unwinds and supplies the continuous paper WP to the front surface printing unit 5. The front surface printing apparatus 5 is, for example, an ink jet printing apparatus that forms an image by ejecting ink droplets, and performs printing on the surface of the continuous paper WP. The reversing device 7 includes a plurality of turn bars (not shown), and reverses the back surface of the continuous paper WP upward. The back surface printing device 9 has the same configuration as the front surface printing device 5, for example, and performs printing on the back surface of the continuous paper WP. The paper discharge unit 11 winds the continuous paper WP processed by the front surface printing device 5 and the back surface printing device 9 around a horizontal axis.

  As shown in FIG. 2, the front surface printing apparatus 5 includes a driving roller 13 for taking in the continuous paper WP from the paper feeding unit 3 on the upstream side. The continuous paper WP unwound from the paper feeding unit 3 by the driving roller 13 is conveyed downstream along the plurality of conveying rollers 15. The front surface printing apparatus 5 includes a driving roller 17 at the most downstream side. Between the driving roller 13 and the driving roller 17, a printing unit 19, a drying unit 21, and an inspection unit 23 are arranged from the upstream side. The printing unit 19 includes an ink jet print head 25. The drying unit 21 dries the portion printed by the printing unit 19. The inspection unit 23 inspects the image printed on the continuous paper WP.

  The printing unit 19 includes, for example, four print heads 25. Specifically, in order from the upstream side, the print head 25 for black (K), the print head 25 for cyan (C), the print head 25 for magenta (M), and the print for yellow (Y). And a head 25. The print heads 25 are arranged at a predetermined interval along the conveyance direction of the continuous paper WP.

  The control unit 27 includes a CPU, a memory, and the like (not shown). The control unit 27 receives print data from a host computer or the like (not shown), drives the drive rollers 13 and 17 based on the print data, and operates the printing unit 19 to eject ink droplets.

  The drying unit 21 includes a guide roller 29 and a heat roller 31. The guide roller 29 guides the continuous paper WP sent in a horizontal posture downward. The heat roller 31 has a built-in heat source, and heats the continuous paper WP wound around the outer peripheral surface to dry the printing surface.

  The inspection unit 23 includes a sensor 33 and the like. Data relating to the printing surface of the continuous paper WP read by the sensor 33 is sent to the control unit 27 and inspected.

  The drive roller 17 on the downstream side of the inspection unit 23 includes a guide roller 35 on the downstream side thereof. The guide roller 35 guides the feeding direction of the continuous paper WP upward in order to send the continuous paper WP that has passed through the inspection unit 23 to the next apparatus.

  When the continuous paper WP stops for a long time between the guide roller 29 of the drying unit 21 and the guide roller 35 on the downstream side of the drive roller 17, the front surface printing apparatus 5 configured in this way Surface abnormalities such as wrinkles, curls, and irregularities having a lower flatness than the printed surface of the continuous paper WP that maintains a flat surface occur. This wrinkle is called cockling. Kokking, for example, when the printing process is finished and the device is stopped, and when the printing process is performed at the beginning of the next day or when the device is stopped for a long time due to a power failure or the like, the printing quality is adversely affected. Avoid as described below.

  The back surface printing apparatus 9 is configured as shown in FIG. Specifically, the back surface printing apparatus 9 has substantially the same configuration as the front surface printing apparatus 5 described above. Here, only the configuration different from the front surface printing apparatus 5 will be described.

  The driving roller 13 of the back surface printing device 9 takes in the continuous paper WP from the reversing device 7. The continuous paper WP that has been printed on the back side and is fed out by the drive roller 17 and the guide roller 35 is taken up by the paper discharge unit 11. Each print head 25 of the printing unit 19 is lifted and lowered by a lifting mechanism 37. The elevating mechanism 37 is operated by the control unit 39. Details of the lifting by the lifting mechanism 37 will be described later. The storage unit 41 is connected to the control unit 39. The storage unit 41 stores in advance a correspondence table between the model of the pre-processing device and a collision avoidance position described later. In the input unit 43, parameters are input by an operator. The parameter here is, for example, the type of a pre-processing device that performs some processing on the printing surface of the continuous paper WP. The control unit 39 performs an operation of transporting the surface abnormal portion to the collision avoidance position from the model input from the input unit 43 and the correspondence table of the storage unit 41.

  Reference is now made to FIG. FIG. 4 is a diagram for explaining the raising and lowering of the print head.

  The elevating mechanism 37 elevates each print head 25. Specifically, the discharge surface of each print head 35 has a print height PH (for example, about 1 to 2 mm) close to the surface of the continuous paper WP and a retreat height EH higher than the print height PH. The print head 35 is moved up and down. The four print heads 25 can be moved up and down independently. The escape height EH is set higher than the height of the abnormal surface portion such as cockling.

  Reference is now made to FIG. FIG. 5 is a diagram for explaining the collision avoidance position.

  Here, the abnormal surface portion is represented by the symbol hf. The surface printing device 5 is determined by the type of the pretreatment device. Furthermore, the occurrence position of the front surface abnormal part hf in the front surface printing apparatus 5 can be specified, and the length of the continuous paper WP between each print head 25 in the back surface printing apparatus 9 and the front surface abnormal part hf can be known. Here, a position corresponding to the length on the transport path to the downstream side surface of each print head 25 is defined as a collision avoidance position with reference to the guide roller 29 of the front surface printing apparatus 5. The collision avoidance position in the print head 25 for black (K) is L (K), the collision avoidance position in the print head 25 for cyan (C) is L (C), and the print head 25 for magenta (M) is Let the collision avoidance position be L (M) and the collision avoidance position in the yellow (Y) print head 25 be L (Y). These collision avoidance positions L are uniquely determined because the physical dimensions are determined when the model of the pretreatment device is determined.

  The control unit 39 reads out the collision avoidance position L of each print head 25 based on the model of the preprocessing device input from the input unit 43 and the correspondence table in the storage unit 41, and causes the collision avoidance process to be performed. In the collision avoidance process, for example, the control unit 39 calculates a conveyance time for the last part of the abnormal surface portion hf to reach the downstream side surface of the print head 25 from the collision avoidance position L and the conveyance speed of the continuous paper WP. This can be realized by transporting the continuous paper WP only for the time. In this embodiment, as will be described later, the four print heads 25 are lowered from the retracted height to the print height in order, so that the movement to the collision avoidance position with the next print head 25 is the difference between the collision avoidance positions. The continuous paper WP may be transported for the transport time according to the above.

  It is preferable that the control unit 39 has a built-in time measuring function for measuring an elapsed time from the time when the apparatus is stopped, and performs collision avoidance processing according to the measurement time when printing is resumed. . Accordingly, after the apparatus is stopped, the collision avoidance process is not necessarily performed, and the lost paper can be suppressed by performing the collision avoidance process only when the elapsed time exceeds a predetermined time (for example, 6 hours).

  The surface printing device 5 described above corresponds to the “pretreatment device” in the present invention, the continuous paper WP corresponds to the “printing medium” in the present invention, and the print head 25 corresponds to the “inkjet head” in the present invention. The back surface printing apparatus 9 corresponds to the “inkjet printing apparatus” in the present invention.

  Next, with reference to FIGS. 6 to 8, the printing process by the inkjet printing system 1 described above will be described. 6 is a flowchart showing the operation of the printing process, FIG. 7 is a schematic diagram showing the operation at the start of printing, and FIG. 8 shows a state where the print head (K) has moved to the collision avoidance position. It is a schematic diagram shown.

  Here, it is assumed that the inkjet printing system 1 has been stopped after the yesterday's processing and the apparatus is powered on the next day.

Step S1
The operator inputs the type of the preprocessing device from the input unit 43 and instructs the start of printing. It is assumed that print data for printing an image or the like on the back surface of the continuous paper WP is received from a host computer (not shown).

Step S2
As shown in FIG. 7, the control unit 39 raises the four print heads 25 to the retracted height EH.

Steps S3 and S4
The control unit 39 conveys the continuous paper WP so that the abnormal surface portion hf reaches the collision avoidance position L (K). When the conveyance is completed, the control unit 39 lowers the black (K) print head 25 to the print height PH as shown in FIG. Further, the control unit 39 causes ink droplets to be ejected from the black (K) print head 25 based on the print data.

Steps S5 and S6
The control unit 39 conveys the continuous paper WP so that the abnormal surface portion hf reaches the collision avoidance position L (C). When the conveyance is completed, the control unit 39 lowers the cyan (C) print head 25 to the print height PH. Further, the control unit 39 causes ink droplets to be ejected from the cyan (C) print head 25 based on the print data.

Steps S7 and S8
The control unit 39 conveys the continuous paper WP so that the abnormal surface portion hf reaches the collision avoidance position L (M). When the conveyance is completed, the control unit 39 lowers the magenta (M) print head 25 to the print height PH. Further, the control unit 39 causes ink droplets to be ejected from the magenta (M) print head 25 based on the print data.

Steps S9 and S10
The control unit 39 conveys the continuous paper WP so that the abnormal surface portion hf reaches the collision avoidance position L (Y). When the conveyance is completed, the control unit 39 lowers the yellow (Y) print head 25 to the printing height PH. Further, the control unit 39 causes ink droplets to be ejected from the print head 25 for yellow (Y) based on the print data.

  Thereafter, since the surface abnormal portion hf does not exist in the continuous paper WP, ink droplets are ejected while the continuous paper WP is conveyed as in a normal printing process.

  The above-described step S2 corresponds to the “inkjet head retracting position moving step” in the present invention, and steps S3, S5, S7, and S9 correspond to the “evasive conveyance step” in the present invention, and steps S4, S6, S8, S10 corresponds to “inkjet head printing position moving step” and “printing step” in the present invention.

  Further, the above-described printing height corresponds to the “printing position” in the present invention, and the retracted height corresponds to the “retracting position” in the present invention.

  According to the present embodiment, the print head 25 is raised to the evacuation height EH, and the continuous paper WP is transported to the collision avoidance position L based on the parameters input in advance. Then, the print head 25 is lowered to the printing height PH, and printing is performed on the continuous paper WP. Since the continuous paper WP is transported to the collision avoidance position L based on the parameters inputted in advance, the surface abnormal portion hf of the continuous paper WP is printed by the simple control of transporting to the predetermined position without using the detecting means. It is possible to print while preventing it from colliding with 19.

  Further, since the surface abnormal portion hf is lowered to the printing height PH in order from the print head 25 that has passed, printing can be performed in order from the lowered print head 25. Accordingly, it is possible to reduce waste paper that is wasted on the continuous paper WP.

  The present invention is not limited to the above embodiment, and can be modified as follows.

  (1) In the above-described embodiments, the continuous paper WP has been described as an example of the print medium. However, the present invention can be applied to a film other than paper as the print medium.

  (2) In the above-described embodiment, the print head 25 is raised to the retracted height EH and then lowered to the print position PH. However, the present invention is not limited to such control. For example, as shown in FIG. 9, after the print head 25 rises to a standby height (standby position) SH higher than the standby height EH and passes through a standby state, the print head 25 drops to the retract height EH and the surface abnormal portion hf. May pass down to the printing height PH.

  (3) In the above-described embodiment, the plurality of print heads at the retreat height EH are sequentially lowered to the print position PH. However, the present invention is not limited to such control. For example, all the print heads 25 may be lowered all at once to the printing height PH when the abnormal surface portion hf is conveyed to the collision avoidance position L (Y) of the most downstream print head 25. Thereby, control can be simplified.

  (4) In the above-described embodiment, the surface printing device 5 is exemplified as the pretreatment device. However, for example, the case where the undercoat liquid coating device arranged on the upstream side of one printing device is used as the pretreatment device. However, the present invention can be applied. Further, although the portion between the guide roller 29 of the drying unit 21 of the front surface printing apparatus 5 and the guide roller 35 on the downstream side of the drive roller 17 is set as a portion where cockling occurs, it is a case where cockling occurs in other portions. However, the present invention can be applied if the location can be specified.

  (5) In the embodiment described above, the type of the pre-processing device is input as a parameter. However, the pre-processing device is not frequently changed and is generally fixed. Only the correspondence table corresponding to the device may be stored in the storage unit 41. Thereby, it is possible to save the trouble of inputting the type of the pre-processing device.

DESCRIPTION OF SYMBOLS 1 ... Inkjet printing system 3 ... Paper feed part 5 ... Front surface printing apparatus 7 ... Inversion apparatus 9 ... Back surface printing apparatus 11 ... Paper discharge part 19 ... Printing part 21 ... Drying part 23 ... Inspection part 25 ... Print head 27 ... Control part 29 35 ... Guiding roller 31 ... Heat roller 37 ... Elevating mechanism 39 ... Control part 41 ... Storage part 43 ... Input part PH ... Printing height EH ... Retraction height hf ... Surface abnormal part L ... Collision avoidance position

Claims (4)

In a printing method of an inkjet printing apparatus including an inkjet head that ejects ink droplets onto a print medium,
An ink-jet head retreat position moving step for moving the ink-jet head to a retreat position higher than a print position for printing on a print medium;
Collision avoidance position where the abnormal surface portion can avoid interference with the ink jet head on the print medium stopped in the conveyance path based on the parameters related to the occurrence position of the abnormal surface portion in the print medium, which are input in advance. Avoidance conveyance step to convey to,
An inkjet head printing position moving step of moving the inkjet head from the retracted position to a printing position;
A printing step of performing printing by discharging ink droplets from the inkjet head while conveying the printing medium;
A printing method for an inkjet printing apparatus, comprising: The printing method of the inkjet printing apparatus according to claim 1,
A plurality of the inkjet heads are provided along the transport direction of the print medium,
The inkjet head retracting position moving step moves the plurality of inkjet heads simultaneously,
In the inkjet printing apparatus, the step of moving the inkjet head printing position sequentially moves the inkjet head from the inkjet head through which the abnormal surface portion has passed. In the printing method of the inkjet printer of Claim 1 or 2,
The avoidance transport step calculates a transport time to a collision avoidance position based on a distance from the position where the abnormal surface portion of the print medium is generated to the inkjet head, and transports the print medium only by the transport time. A printing method for an ink jet printing apparatus. In the printing method of the inkjet printing apparatus in any one of Claim 1 to 3,
The printing method for an ink jet printing apparatus, wherein the parameter is a type of a pretreatment apparatus for the print medium connected upstream.

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